N-vinyl lactam-based crosslinked polymer, cosmetic, absorbent agent for ink, and absorbent composite

Abstract

The invention aims to provide a crosslinked polymer having excellent moisture retention properties, an excellent ethanol absorption capacity, excellent adhesiveness to the skin when applied to the skin as a cosmetic, and a high concentration of an effective component. The invention relates to a N-vinyl lactam-based crosslinked polymer including: a structural unit derived from a N-vinyl lactam; and a structural unit derived from a crosslinking agent, the N-vinyl lactam-based crosslinked polymer having an ethanol absorption capacity of 3 to 40 g per 1 g of the N-vinyl lactam-based crosslinked polymer, the N-vinyl lactam-based crosslinked polymer containing a particle having an aspect ratio determined by the following method of 1.15 to 10 in a proportion of 10% to 100% (by number) of the total number of the N-vinyl lactam-based crosslinked polymer and having a proportion of an extractable of 35 mass % or less in 100 mass % of the entire polymer, the method being “method of measuring aspect ratio” in which the aspect ratio is determined as a value obtained by measuring the major and minor axes of a primary particle of the N-vinyl lactam-based cross-linked polymer with an optical or electron microscope and dividing the major axis by the minor axis.

Claims

1. A N-vinyl lactam-based crosslinked polymer-containing composition, the composition comprising a N-vinyl lactam-based crosslinked polymer that comprises: a structural unit derived from a N-vinyl lactam; and a structural unit derived from at least one selected from the group consisting of a crosslinkable monomer and a crosslinking agent, wherein the N-vinyl lactam-based crosslinked polymer has an ethanol absorption capacity of 3 to 40 g per 1 g of the N-vinyl lactam-based crosslinked polymer, the N-vinyl lactam-based crosslinked polymer contains a particle having an aspect ratio determined by the following method of 1.15 to 10 in a proportion of 10% to 100% (by number) of a total number of the N-vinyl lactam-based crosslinked polymer and having a proportion of an extractable of 35 mass % or less in 100 mass % of the entire polymer, “Method of measuring aspect ratio” the aspect ratio is determined as a value obtained by measuring the major and minor axes of a primary particle of the N-vinyl lactam-based cross-linked polymer with an optical or electron microscope and dividing the major axis by the minor axis, a proportion of a residual monomer in the N-vinyl lactam-based crosslinked polymer is 200 ppm or less in 100 mass % of the N-vinyl lactam-based crosslinked polymer, and the composition has a proportion of a residual monomer of 200 ppm or less in 100 mass % of the N-vinyl lactam-based crosslinked polymer.

2. The N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, wherein the N-vinyl lactam-based crosslinked polymer has a viscosity measured under the following conditions of 100 mPa.Math.s or higher and lower than 10000 mPa.Math.s, “Viscosity measurement conditions” sample: a 5 mass % aqueous dispersion of the N-vinyl lactam-based crosslinked polymer after 16-hour stirring; measuring equipment: the sample is measured using a B-type viscometer at 25° C.; and measurement conditions: Rotor No. 4, rotation speed: 30 rpm.

3. The N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, wherein the N-vinyl lactam-based crosslinked polymer includes the structural unit derived from a N-vinyl lactam in a proportion of 30 to 100 mol % in 100 mol % of all structural units.

4. The N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, wherein the N-vinyl lactam-based crosslinked polymer includes a structural unit derived from a N-vinyl lactam and at least one selected from the group consisting of a structural unit derived from a crosslinkable monomer and a structural unit derived from a crosslinking agent, and the N-vinyl lactam-based crosslinked polymer contains the structural unit derived from at least one selected from the group consisting of a crosslinkable monomer and a crosslinking agent in a ratio of 0.01 to 2 mol % to 100 mol % of all structural units.

5. The N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, wherein the crosslinkable monomer includes at least one selected from the group consisting of triallyl cyanurate, pentaerythritol (di, tri, or tetra)(meth)allyl ethers, triallyl isocyanurate, triallyl phosphate, triallylamine, diallyl carbonate, 1,3-bis(allyloxy)-2-propanol, divinylethylene urea, 1,4-butylene bis(N-vinylamide), and (di, tri, tetra, penta, hexa, hepta, or octa)allyl sucrose.

6. The N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, wherein the crosslinkable monomer includes at least one selected from the group consisting of pentaerythritol (di, tri, or tetra)(meth)allyl ethers, diallyl carbonate, 1,3-bis(allyloxy)-2-propanol, divinylethylene urea, 1,4-butylene bis(N-vinylamide), and (di, tri, tetra, penta, hexa, hepta, or octa)allyl sucrose.

7. The N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, wherein the N-vinyl lactam-based crosslinked polymer contains a structural unit derived from least one compound selected from the group consisting of triallyl cyanurate, pentaerythritol (di, tri, or tetra)(meth)allyl ethers, and (di, tri, tetra, penta, hexa, hepta, or octa)allyl sucrose.

8. The N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, wherein the N-vinyl lactam-based crosslinked polymer has an average particle size of 0.1 to 100μm.

9. A deodorant comprising the N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1.

10. A deodorizer comprising the deodorant according to claim 9.

11. A method of providing a deodorizing effect, comprising exposing an environment to the deodorant according to claim 9.

12. A cosmetic comprising the N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1.

13. A method of providing a cosmetic effect, comprising externally applying the cosmetic of claim 12.

14. An ink absorbing agent comprising the N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1.

15. An absorbent material comprising the ink absorbing agent according to claim 14.

16. An ink-containing composition comprising the ink absorbing agent according to claim 14 and ink absorbed by the ink absorbing agent.

17. A printer comprising the ink absorbing agent according to claim 14.

18. A printing method, comprising ink printing with the printer of claim 17.

19. A method of producing the N-vinyl lactam-based crosslinked polymer-containing composition according to claim 1, the method comprising polymerizing a monomer component containing a N-vinyl lactam-based monomer and forming a crosslinked structure.

20. The method of producing the N-vinyl lactam-based crosslinked polymer-containing composition according to claim 19, wherein the method uses a polymerization initiator in the polymerizing in an amount of 0.1 to 10 g relative to 1 mol of the monomer component.

21. A N-vinyl lactam-based crosslinked polymer-containing composition, the composition comprising a N-vinyl lactam-based crosslinked polymer that comprises: a structural unit derived from a N-vinyl lactam; and a structural unit derived from at least one selected from the group consisting of a crosslinkable monomer and a crosslinking agent, wherein the N-vinyl lactam-based crosslinked polymer has an ethanol absorption capacity of 3 to 40 g per 1 g of the N-vinyl lactam-based crosslinked polymer, the N-vinyl lactam-based crosslinked polymer contains a particle having an aspect ratio determined by the following method of 1.15 to 10 in a proportion of 10% to 100% (by number) of a total number of the N-vinyl lactam-based crosslinked polymer and having a proportion of an extractable of 35 mass % or less in 100 mass % of the entire polymer, “Method of measuring aspect ratio” the aspect ratio is determined as a value obtained by measuring the major and minor axes of a primary particle of the N-vinyl lactam-based cross-linked polymer with an optical or electron microscope and dividing the major axis by the minor axis, a proportion of a residual monomer in the N-vinyl lactam-based crosslinked polymer is 200 ppm or less in 100 mass% of the N-vinyl lactam-based crosslinked polymer, and the composition has a proportion of a compound represented by the following formula (3) of 2 mass % or less in 100 mass % of the N-vinyl lactam-based crosslinked polymer: ##STR00005## wherein R.sup.4 represents a hydrogen atom or an optionally substituted C1-C10 alkyl group; and y represents an integer of 1 to 3.

22. A N-vinyl lactam-based crosslinked polymer-containing composition, the composition comprising a N-vinyl lactam-based crosslinked polymer that comprises: a structural unit derived from a N-vinyl lactam; and a structural unit derived from at least one selected from the group consisting of a crosslinkable monomer and a crosslinking agent, wherein the N-vinyl lactam-based crosslinked polymer has an ethanol absorption capacity of 3 to 40 g per 1 g of the N-vinyl lactam-based crosslinked polymer, the N-vinyl lactam-based crosslinked polymer contains a particle having an aspect ratio determined by the following method of 1.15 to 10 in a proportion of 10% to 100% (by number) of a total number of the N-vinyl lactam-based crosslinked polymer and having a proportion of an extractable of 35 mass % or less in 100 mass % of the entire polymer, “Method of measuring aspect ratio” the aspect ratio is determined as a value obtained by measuring the major and minor axes of a primary particle of the N-vinyl lactam-based cross-linked polymer with an optical or electron microscope and dividing the major axis by the minor axis, a proportion of a residual monomer in the N-vinyl lactam-based crosslinked polymer is 200 ppm or less in 100 mass % of the N-vinyl lactam-based crosslinked polymer, and the composition has a proportion of an extractable of 35 mass % or less in 100 mass % of the N-vinyl lactam-based crosslinked polymer.

Description

EXAMPLE

(1) The invention is described in more detail below with reference to, but not limited to, examples. Unless otherwise specified, “part(s)” means “part(s) by weight” and “%” means “% by mass”.

(2) <Evaluation of Liquid Absorption Capacities for Solvent (Including Deionized Water) and Solution>

(3) About 0.1 g of a crosslinked polymer was precisely weighed (mass: W5 (g)) and put into a 4 cm×5 cm nonwoven fabric tea bag, and the tea bag was heat-sealed. These operations were performed in a room at a temperature of 23±2° C., a relative humidity of 50±5%, and atmospheric pressure. The tea bag was placed in a 50-mL (specified volume) glass screw tube and immersed in a solvent or a solution (in the case of deionized water, it has a conductivity of 10 μS/cm or lower) for 24 hours at room temperature (temperature: 23±2° C.) and atmospheric pressure. In the case of using liquid that is slowly absorbed, such as oil, the tea bag was immersed therein at 40° C. for 24 hours and then cooled for 10 minutes. Subsequently, the tea bag was taken out by pinching the end of the tea bag with tweezers, placed one face down on KIMTOWEL (Nippon Paper Crecia Co., Ltd.), and allowed to stand for five seconds. Then, the tea bag was placed the other face down on KIMTOWEL and allowed to stand for five seconds so that the liquid was removed. Then, the mass of the tea bag (W6 (g)) was weighed. Separately, the same operations were performed without a crosslinked polymer. Then, the mass of the tea bag (W4 (g)) was measured as a blank. The liquid absorption rate was determined according to the following equation as the liquid absorption capacity.
Liquid absorption rate (g/g)=(W6 (g)−W4 (g))/W5 (g)
<Measurement of Aspect Ratio>

(4) The aspect ratio was determined by measuring the major and minor axes of cyclic N-vinyl lactam-based crosslinked polymer particles with an optical microscope and dividing the major axis by the minor axis. The aspect ratio was calculated by analyzing image data of a sample obtained from an optical microscope using a “particle image analysis system, Morphologi G3 (product of Malvern in Spectris Co., Ltd.)”. The aspect ratios of any 100 or more particles were measured, and the average value of the aspect ratios was determined. Further, in the particles sorted in ascending order of the aspect ratio, the aspect ratio of the particle at 10% by number of all particles, the aspect ratio of the particle at 50% by number of all particles, and the aspect ratio of the particle at 90% by number of all particles were calculated.

(5) In addition to the above described system, the aspect ratio may be measured by analyzing image data of a sample obtained from an optical or electron microscope using “image analyzing particle size distribution measurement software, Mac-view, ver. 4 (Mountech Co., Ltd.)”.

(6) <Quantification of Residual Monomer (N-Vinyl Lactam-Based Monomer) and by-Product (Compound Represented by the Formula (3))>

(7) A 110-mL screw tube was charged with about 1 g of a particulate crosslinked polymer (mass: W7 (g)) and about 100 g of deionized water (mass: W8 (g)) (conductivity: 10 μS/cm or lower), which were precisely weighed. A stirrer bar was placed in the tube, and the tube was sealed. These operations were performed in a room at a temperature of 23±2° C., a relative humidity of 50±5%, and atmospheric pressure. Thereafter, the contents were stirred using a magnetic stirrer at room temperature (temperature: 23±2° C.) and atmospheric pressure for 16 hours or longer (rotation speed: 600 rpm). These operations extracted the residual monomer of the particulate crosslinked polymer (N-vinyl lactam-based monomer) and a by-product (compound represented by the formula (3)). The resulting extract solution was quantitatively analyzed by liquid chromatography under the following conditions.

(8) Apparatus: “NANOSPACE SI-2”, Shiseido Company, Limited

(9) Column: “CAPCELLPAK C18 UG120” (20° C.), Shiseido Company, Limited

(10) Eluent: Methanol for LC (Wako Pure Chemical Industries, Ltd.)/super pure water=1/24 (mass ratio) supplemented with 0.04 mass % of sodium 1-heptanesulfonate

(11) Flow rate: 100 μL/min

(12) Content (ppm)=measured value (ppm)×(W7 (g)+W8 (g))/W7 (g)

(13) <Measurement of Extractable>

(14) A 110-mL glass screw tube was charged with about 1 g of a particulate crosslinked polymer (mass: W9 (g)) and about 100 g of deionized water (mass: W10 (g)) (conductivity: 10 μS/cm or lower), which were precisely weighed. A stirrer bar was placed in the tube, and the tube was sealed. These operations were performed in a room at a temperature of 23±2° C., a relative humidity of 50±5%, and atmospheric pressure. Thereafter, the contents were stirred using a magnetic stirrer at room temperature (temperature: 23±2° C.) and atmospheric pressure for 16 hours or longer (rotation speed: 600 rpm). The resulting mixture was filtered through a qualitative filter paper (Model: No. 2, Advantec). Thus, an extract solution of an extractable was obtained.

(15) Next, about 10 g of the extract solution (mass: W12 (g)) was put into an aluminum cup (mass: W11 (g)) having an about 5 cm diameter bottom face. The solution was allowed to stand in a dryer having a constant temperature of 120° C. for two hours, and thereby dried. After the drying, the sum of the mass (W13 (g)) of the aluminum cup and the mass of the extractable was measured, and the amount of extractable was determined using the following equation.
Amount of extractable (mass %)=((W13 (g)−W11 (g))/(W12 (g)×W9 (g)/W10 (g)))×100
<Measurement of Average Particle Size>

(16) The 50% cumulative value was determined as an average particle size using a dry particle size distribution analyzer (Model: Mastersizer 3000, dry system, product of Malvern in Spectris Co., Ltd.). The measurement was performed under the following conditions.

(17) <Measurement Conditions>

(18) Dry-type laser diffraction scattering

(19) Dispersion pressure: 1 bar

(20) Particle refractive index: 1.52

(21) Particle absorptivity: 0.01

(22) Particle shape: Non-spherical

(23) Medium name: Air

(24) Measurement range: 0.1 to 3500 μm

(25) <Measurement of Viscosity>

(26) A 50-mL glass screw tube was charged with 2.5 g of a particulate crosslinked polymer and 47.5 g of deionized water (conductivity: 10 μS/cm or lower), which were precisely weighed. A stirrer bar was placed in the tube, and the tube was sealed. These operations were performed in a room at a temperature of 23±2° C., a relative humidity of 50±5%, and atmospheric pressure. Thereafter, the contents were stirred using a magnetic stirrer at room temperature (temperature: 23±2° C.) and atmospheric pressure for 16 hours to prepare a 5 mass % aqueous dispersion of a cyclic N-vinyl lactam-based crosslinked polymer. Subsequently, the temperature of the aqueous solution was set at 25° C., and the viscosity was measured using a B-type viscometer (BM type, Toki Sangyo Co., Ltd.) (Rotor No. 4, rotation speed: 30 rpm).

Example 1-1

(27) A desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) having a stainless-steel (SUS304) body vessel was charged with 130.0 parts of N-vinylpyrrolidone (hereinafter, also referred to as VP, Nippon Shokubai Co., Ltd.), 0.52 parts (0.18 mol % relative to VP) of triallyl cyanurate (hereinafter, also referred to as CTA) as a crosslinkable monomer, and 304.6 parts of deionized water. Subsequently, the vessel was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 1.96 parts (0.25 g per 1 mol of the sum of VP and CTA used) of a 15 mass % aqueous solution of 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (hereinafter, also referred to as “VA-044”) as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, 65.0 parts of a 1 mass % aqueous solution of malonic acid was added over three minutes, followed by stirring at 90° C. for 60 minutes. In addition, 32.5 parts of a 2 mass % aqueous solution of diethanolamine was added over three minutes, followed by stirring for 30 minutes. The resulting gel was dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used) to obtain a dried VP crosslinked polymer. The dried VP crosslinked polymer was ground using a grinder. Thus, a particulate VP crosslinked polymer (1-1) was obtained.

(28) The physical properties of the VP crosslinked polymer (1-1) were evaluated by the above-described methods. In the evaluation, particles having a size of 250 to 500 μm of the VP crosslinked polymer (1-1) were used, which were obtained by classification of the VP crosslinked polymer (1) using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The results are shown in Tables 1-1 and 1-2.

Example 1-2

(29) A desktop kneader (Model: PNV-5H, Chuorika Co., Ltd.) was charged with 900.0 parts of VP, 4.05 parts (0.20 mol % relative to VP) of CTA as a crosslinkable monomer, and 2109.5 parts of deionized water. Subsequently, the kneader was purged with nitrogen at 400 mL/min for 40 minutes. Then, nitrogen was introduced at 100 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 24.11 parts (0.45 g per 1 mol of the sum of VP and CTA used) of a 15 mass % aqueous solution of 2,2′-azobis(2-methylpropionamidine) dihydrochloride (hereinafter, also referred to as “V-50”) as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, 150.0 parts of a 3 mass % aqueous solution of malonic acid was added over five minutes, followed by stirring at 90° C. for 60 minutes. In addition, 30.0 parts of a 15 mass % aqueous solution of diethanolamine was added over three minutes, followed by stirring for 30 minutes. The resulting gel was dried at 120° C. for three hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used, eight stainless steel vats each having external dimensions of 206×267×40 H (mm) were used) to obtain a dried VP crosslinked polymer. The dried VP crosslinked polymer was ground using a grinder. Thus, a particulate VP crosslinked polymer (1-2) was obtained.

(30) The physical properties of the VP crosslinked polymer (1-2) were evaluated by the above-described methods. In the evaluation, particles having a size of 250 to 500 μm of the VP crosslinked polymer (1-2) were used, which were obtained by classification of the VP crosslinked polymer (1-2) using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The results are shown in Table 1-1.

Example 1-3

(31) A desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) having a stainless-steel (SUS304) body vessel was charged with 130.0 parts of VP, 1.30 parts (0.45 mol % relative to VP) of CTA as a crosslinkable monomer, and 306.4 parts of deionized water. Subsequently, the vessel was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 1.97 parts (0.25 g per 1 mol of the sum of VP and CTA used) of a 15 mass % aqueous solution of VA-044 as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, the resulting gel was dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used) to obtain a dried VP crosslinked polymer. The dried VP crosslinked polymer was ground using a grinder. Thus, a particulate VP crosslinked polymer (1-3) was obtained.

(32) The physical properties of the VP crosslinked polymer (1-3) were evaluated by the above-described methods. In the evaluation, particles having a size of 250 to 500 μm of the VP crosslinked polymer (1-3) were used, which were obtained by classification of the VP crosslinked polymer (1-3) using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The results are shown in Table 1-1.

Comparative Example 1-1

(33) A 1-L polypropylene (hereinafter, referred to as “PP”) container was charged with 130.0 parts of VP, 0.13 parts (0.04 mol % relative to VP) of CTA as a crosslinkable monomer, and 303.6 parts of deionized water. Subsequently, stirring of the contents was started with a magnetic stirrer, and the container was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and the contents were heated to 56° C. under stirring. After the temperature of the liquid was stabilized at 56° C., 1.95 parts (0.25 g per 1 mol of the sum of VP and CTA used) of a 15 mass % aqueous solution of VA-044 as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes to complete the polymerization. The resulting gel was pulverized using a desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.), but it was only kneaded with the blade of the kneader but not pulverized. Subsequently, the gel was pulverized by hands and dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used) to obtain a comparative dried VP crosslinked polymer. The comparative dried VP crosslinked polymer was ground using a grinder. Thus, a particulate comparative VP crosslinked polymer (1-1) was obtained.

(34) The physical properties of the comparative VP crosslinked polymer (1-1) were evaluated by the above-described methods. In the evaluation, particles having a size of 250 to 500 μm of the comparative VP crosslinked polymer (1-1) were used, which were obtained by classification of the comparative VP crosslinked polymer (1-1) using JIS standard 250 μm-mesh and 500 μm-mesh sieves.

(35) The results are shown in Table 1-1.

Comparative Example 1-2

(36) A desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) having a stainless-steel (SUS304) body vessel was charged with 130.0 parts of VP, 0.26 parts (0.09 mol % relative to VP) of CTA as a crosslinkable monomer, and 303.9 parts of deionized water. Subsequently, the vessel was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 1.95 parts (0.25 g per 1 mol of the sum of VP and CTA used) of a 15 mass % aqueous solution of VA-044 as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while rotating the blade of the kneader to complete the polymerization. The gel was kneaded with the blade of the kneader but not pulverized. Subsequently, the resulting gel was pulverized by hands and dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used) to obtain a comparative dried VP crosslinked polymer. The comparative dried VP crosslinked polymer was ground using a grinder. Thus, a particulate comparative VP crosslinked polymer (1-2) was obtained.

(37) The physical properties of the comparative VP crosslinked polymer (1-2) were evaluated by the above-described methods. In the evaluation, particles having a size of 250 to 500 μm of the comparative VP crosslinked polymer (1-2) were used, which were obtained by classification of the comparative VP crosslinked polymer (1-2) using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The results are shown in Table 1-1.

Comparative Example 1-3

(38) A desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) having a stainless-steel (SUS304) body vessel was charged with 130.0 parts of VP, 2.60 parts (0.89 mol % relative to VP) of CTA as a crosslinkable monomer, and 309.4 parts of deionized water. Subsequently, the vessel was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 6.63 parts (1.12 g per 1 mol of the sum of VP and CTA used) of a 20 mass % aqueous solution of VA-044 as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, the resulting gel was dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used) to obtain a comparative dried VP crosslinked polymer. The comparative dried VP crosslinked polymer was ground using a grinder. Thus, a particulate comparative VP crosslinked polymer (1-3) was obtained.

(39) The physical properties of the comparative VP crosslinked polymer (1-3) were evaluated by the above-described methods. In the evaluation, particles having a size of 250 to 500 μm of the comparative VP crosslinked polymer (1-3) were used, which were obtained by classification of the comparative VP crosslinked polymer (1-3) using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The results are shown in Table 1-1.

(40) TABLE-US-00001 TABLE 1-1 Comparative Comparative Comparative Example 1-1 Example 1-2 Example 1-3 Example 1-1 Example 1-2 Example 1-3 Crosslinked polymer Comparative Comparative Comparative VP crosslinked VP crosslinked VP crosslinked VP crosslinked VP crosslinked VP crosslinked polymer (1-1) polymer (1-2) polymer (1-3) polymer (1-1) polymer (1-2) polymer (1-3) Amount of crosslinkable monomer 0.18 0.20 0.45 0.04 0.09 0.89 (mol %) *1 Deionized water absorption 22 24 16 40 32 12 capacity (g/g) Ethanol absorption capacity (g/g) 21 24 15 38 31 10 Amount of by-product 4015 2701 1734 4083 3389 1302 (Compound represented by formula (2)) (ppm) Amount of extractable (wt %) 10 12 3 52 20 3 *1 Amount relative to 100 mol % of N-vinyl lactam-based monomer

(41) TABLE-US-00002 TABLE 1-2 Number of Aspect ratio particles measured Average 10% 50% 90% VP crosslinked 8120 1.41 1.11 1.37 2.07 polymer (1-1)

Example 2-1

(42) A desktop kneader (Model: PNV-5H, Chuorika Co., Ltd.) was charged with 900.0 parts of N-vinylpyrrolidone (hereinafter, also referred to as VP, Nippon Shokubai Co., Ltd.), 12.6 parts (0.6 mol % relative to VP) of pentaerythritol triallyl ether (trade name: neoallyl P-30M, hereinafter, also referred to as P-30M, Osaka Soda Co., Ltd.) (81 mass % of pentaerythritol triallyl ether, 11 mass % of pentaerythritol diallyl ether, 7 mass % of pentaerythritol tetraallyl ether) as a crosslinkable monomer, 4.5 parts of a 1 mass % aqueous solution of diethanolamine, and 2124.9 parts of deionized water. Here, P-30M was premixed with the aqueous solution of diethanolamine so that the pH was adjusted to 6 or higher before addition. The kneader was purged with nitrogen at 400 mL/min for 40 minutes. Then, nitrogen was introduced at 100 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 42.59 parts (0.78 g per 1 mol of the sum of VP and P-30M used) of a 15 mass % aqueous solution of 2,2′-azobis(2-methylpropionamidine) dihydrochloride (hereinafter, also referred to as “V-50”) as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, 225.0 parts of a 2 mass % aqueous solution of malonic acid was added over five minutes, followed by stirring at 90° C. for 60 minutes. In addition, 50.0 parts of a 9 mass % aqueous solution of diethanolamine was added over three minutes, followed by stirring for 30 minutes. The resulting gel was dried at 120° C. for three hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used, eight stainless steel vats each having external dimensions of 206×267×40 H (mm) were used) to obtain a dried VP crosslinked polymer. The dried VP crosslinked polymer was preground using a grinder, followed by gringing using a target-type jet mill to obtain a particulate VP crosslinked polymer (2-1).

(43) The water absorption capacity, ethanol absorption capacity, average particle size, aspect ratio, amount of a residual monomer (N-vinyl lactam-based monomer content), amount of a by-product, and an extractable of the VP crosslinked polymer (2-1) were determined. The measurement was performed by the above-described method. The results are shown in Tables 2-1 and 2-2.

Example 2-2

(44) A desktop kneader (Model: PNV-5H, Chuorika Co., Ltd.) was charged with 1000.0 parts of VP, 15.0 parts (0.65 mol % relative to VP) of P-30M (the pH was adjusted to 6 or higher using diethanolamine) as a crosslinkable monomer, and 2368.33 parts of deionized water. Subsequently, the kneader was purged with nitrogen at 400 mL/min for 40 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 47.37 parts (0.78 g per 1 mol of the sum of VP and P-30M used) of a 15 mass % aqueous solution of V-50 as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, 500.0 parts of a 1.4 mass % aqueous solution of malonic acid was added over three minutes, followed by stirring at 90° C. for 60 minutes. In addition, 250.0 parts of a 2.8 mass % aqueous solution of diethanolamine was added over three minutes, followed by stirring for 30 minutes. The resulting gel was dried at 120° C. for three hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used, eight stainless steel vats each having external dimensions of 206×267×40 H (mm) were used) to obtain a dried VP crosslinked polymer. The dried VP crosslinked polymer was freeze ground in the presence of liquid nitrogen to obtain a particulate VP crosslinked polymer (2-2).

(45) The physical properties of the VP crosslinked polymer (2-2) were evaluated by the above-described methods. The results are shown in Table 2-1.

Example 2-3

(46) A desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) having a stainless-steel (SUS304) body vessel was charged with 130.0 parts of VP, 0.52 parts (0.18 mol % relative to VP) of triallyl cyanurate (hereinafter, also referred to as CTA) as a crosslinkable monomer, and 304.6 parts of deionized water. Subsequently, the vessel was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 1.96 parts (0.25 g per 1 mol of the sum of VP and CTA used) of a 15 mass % aqueous solution of 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (hereinafter, also referred to as “VA-044”) as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, 65.0 parts of a 1 mass % aqueous solution of malonic acid was added over three minutes, followed by stirring at 90° C. for 60 minutes. In addition, 32.5 parts of a 2 mass % aqueous solution of diethanolamine was added over three minutes, followed by stirring for 30 minutes. The resulting gel was dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used) to obtain a dried VP crosslinked polymer. The dried VP crosslinked polymer was ground using a grinder to a size that passed through a JIS standard 38 μm-mesh sieve. Thus, a particulate VP crosslinked polymer (2-3) was obtained.

(47) The physical properties of the VP crosslinked polymer (2-3) were evaluated by the above-described methods. The results are shown in Table 2-1.

Comparative Example 2-1

(48) A flask equipped with components such as a reflux condenser, a thermometer, a nitrogen gas inlet tube, and a T.K. homogenizer (stirrer, Tokushu Kika Kogyo Co., Ltd.), was charged with an aqueous solution prepared by dissolving 0.5 parts of polyoxyethylene alkyl sulfoammonium (trade name: HITENOL N-08, Dai-Ichi Kogyo Seiyaku Co., Ltd.) as a dispersion stabilizer to 400 parts of deionized water. Separately, a monomer composition containing 99.5 parts of stearyl acrylate and 0.5 parts of ethylene glycol dimethacrylate (hereinafter, also referred to as EGDMA) as a crosslinkable monomer was mixed with 1.0 part (3.24 g per 1 mol of the sum of stearyl acrylate and EGDMA used) of lauroyl peroxide as a polymerization initiator (organic peroxide) to prepare a mixture. The mixture was added to the flask containing the aqueous solution. Then, the contents were vigorously stirred at a rotational speed of 4000 rpm for five minutes to obtain a uniform suspension. The suspension was heated to 75° C. while nitrogen gas was blown into the flask. Then, a radical polymerization reaction was performed at this temperature for two hours under stirring to obtain a fine particle dispersion. The fine particle dispersion was separated into solid and liquid phases by natural precipitation. The resulting cake was dried by hot air at 50° C. for 10 hours. Thus, an oil-absorbing resin (comparative crosslinked polymer (2-1)) was obtained.

(49) The physical properties of the comparative crosslinked polymer (2-1) were evaluated by the above-described methods. The results are shown in Table 2-1.

Comparative Example 2-2

(50) A 250-mL polypropylene container was charged with 30.0 parts of acrylic acid (Nippon Shokubai Co., Ltd., 80 mass % aqueous solution) (hereinafter, also referred to as AA), 12.14 parts of sodium hydroxide (48 mass % aqueous solution), 0.021 parts (0.01 mol % relative to AA) of polyethylene glycol dimethacrylate (NK ester A-400, Shin-Nakamura Chemical Co., Ltd., number of moles of EO added: 9 mol) (hereinafter, also referred to as A-400) as a crosslinkable monomer, and 42.2 parts of deionized water (AA and sodium hydroxide were mixed before addition of A-400 and deionized water). Subsequently, stirring of the contents was started with a magnetic stirrer, and the container was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and 0.33 parts (0.12 g per 1 mol of the sum of AA and A-400 used) of a 15 mass % aqueous solution of sodium persulfate as an initiator and 0.04 parts of a 0.5 mass % aqueous solution of L-ascorbic acid was added to start polymerization under stirring. A gel formed by the polymerization reaction was aged at 90° C. for 30 minutes to complete the polymerization. The gel was pulverized using a desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) and then dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, one stainless steel vat having external dimensions of 206×267×40 H (mm) was used) to obtain a dried AA-based crosslinked polymer (comparative crosslinked polymer (2-2)). The crosslinked polymer was ground using a grinder. Thus, a particulate comparative crosslinked polymer (2-2) was obtained.

(51) The average particle size of the comparative crosslinked polymer (2-2) was 52.1 μm, determined by the above-described method.

Example 2-4

(52) A dried VP crosslinked polymer was obtained in the same manner as in Example 2-3 except that the gel was dried at 120° C. for three hours. Subsequently, the dried VP crosslinked polymer was ground using a grinder and classified using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The powder that passed through the 500 μm-mesh sieve and left on the 250 μm-mesh sieve was obtained as a particulate VP crosslinked polymer (VP crosslinked polymer (2-4)).

(53) The physical properties of the VP crosslinked polymer (2-4) were evaluated by the above-described methods. The results are shown in Tables 2-1 and 2-2.

(54) TABLE-US-00003 TABLE 2-1 Comparative Example 2-1 Example 2-2 Example 2-3 Example 2-4 Example 2-1 Crosslinked polymer Comparative VP crosslinked VP crosslinked VP crosslinked VP crosslinked crosslinked polymer (2-1) polymer (2-2) polymer (2-3) polymer (2-4) polymer (2-1) Deionized water absorption 25 25 21 22 1 capacity (g/g) Ethanol absorption capacity 24 24 21 21 1 (g/g) (Average) Aspect ratio 1.3 1.3 1.4 1.4 1.0 Average particle size (μm) 3 9 19 448 11 Amount of N-vinyl lactam- 106 62 69 10 0 based monomer (ppm) Amount of by-product 4899 4771 3269 4015 0 (Compound represented by formula (2)) (ppm) Amount of extractable (%) 19 17 16 10 1

(55) TABLE-US-00004 TABLE 2-2 Number of Aspect ratio particles measured Average 10% 50% 90% VP crosslinked 14406 1.27 1.08 1.25 1.55 polymer (2-1) VP crosslinked 8120 1.41 1.11 1.37 2.07 polymer (2-4)

<Evaluation Example 2-1> Evaluation of Oil Absorption Capacity

(56) The oil absorption capacities of the VP crosslinked polymers (2-1) to (2-4) obtained in Examples 2-1 to 2-4 and the comparative crosslinked polymers (2-1) and (2-2) obtained in Comparative Examples 2-1 and 2-2 were evaluated. The evaluation was performed in the following way.

(57) (Evaluation Method)

(58) About 0.1 g of a crosslinked body was precisely weighed (mass: W15 (g)) and put into a 4 cm×5 cm nonwoven fabric tea bag, and the tea bag was heat-sealed. These operations were performed in a room at a temperature of 23±2° C., a relative humidity of 50±5%, and atmospheric pressure. The tea bag was immersed in linoleic acid as an oil and placed in a dryer at a temperature of 40° C. After 24 hours, the test object was taken out from the dryer and cooled for 10 minutes. The tea bag was taken out from the oil by pinching the end of the tea bag with tweezers, placed one face down on KIMTOWEL (Nippon Paper Crecia Co., Ltd.), and allowed to stand for five seconds. Subsequently, the tea bag was placed the other face down on KIMTOWEL and allowed to stand for five seconds so that the liquid was removed. Then, the mass of the tea bag (W16 (g)) was measured. Separately, the same operations were performed without a crosslinked polymer. Then, the mass of the tea bag (W14 (g)) was measured as a blank. The liquid absorption rate was determined according to the following equation as oil absorption capacity.
Liquid absorption rate (g/g)=(W16 (g)−W14 (g))/W15 (g)

(59) The results are shown in Table 2-3.

(60) TABLE-US-00005 TABLE 2-3 Crosslinked body Comparative Comparative VP crosslinked VP crosslinked VP crosslinked VP crosslinked crosslinked crosslinked polymer (2-1) polymer (2-2) polymer (2-3) polymer (2-4) polymer (2-1) polymer (2-2) Oil absorption 31 31 32 32 2 1 capacity (g/g)
<Evaluation Example 2-2> Sensory Evaluation

(61) First, 3% aqueous solutions of the VP crosslinked polymers (2-1) to (2-3) obtained in Examples 2-1 to 2-3, the comparative crosslinked polymers (2-1) and (2-2) obtained in Comparative Examples 2-1 and 2-2, and polyvinylpyrrolidone (polyvinylpyrrolidone K-30, Nippon Shokubai Co., Ltd., K value (catalog value): 27.0 to 33.0, hereinafter, also referred to as PVP K-30) were prepared (97 g of ion exchange water was added to 3 g of each of the crosslinked polymers and PVP K-30 to prepare an aqueous solution or gelled substance). Each solution was applied to the inner side of a forearm of ten panel members and the coated part was washed with lukewarm water. The panel members evaluated the feeling of use of the aqueous solutions.

(62) They evaluated the four items: moist feeling, no stickiness, applicability to the skin (application feeling), and adhesion feeling. The results are shown in Table 2-4.

(63) In the table, the results are expressed as follows: Excellent: more than 8 out of 10 members evaluated good, Good: 6 or more out of 10 members evaluated good, Fair: 4 or more out of 10 members evaluated good, Bad: less than 4 out of 10 members evaluated good. The following results demonstrate that the products according to the invention provide less stickiness, excellent moist feeling, good applicability to the skin, and good adhesion feeling.

(64) TABLE-US-00006 TABLE 2-4 Polymer Comparative Comparative VP crosslinked VP crosslinked VP crosslinked crosslinked crosslinked polymer (2-1) polymer (2-2) polymer (2-3) polymer (2-1) polymer (2-2) PVP K-30 Moist feeling Excellent Excellent Excellent Poor Good Poor No stickiness Excellent Excellent Excellent Excellent Poor Poor Applicability to skin Excellent Excellent Excellent Fair Poor Good (application feeling) Adhesion feeling Excellent Excellent Excellent Poor Fair Fair

<Example 2-5> Preparation of Foundation

(65) A foundation having the formulation shown in Table 2-5 was prepared using the VP crosslinked polymer (2-1) obtained in Example 2-1.

(66) (Preparation Method)

(67) The components were stirred at high speed and uniformly mixed. This foundation had excellent color developability and provided moist feeling.

(68) TABLE-US-00007 TABLE 2-5 Amount Component No. Example 2-5 (weight %) 1 VP crosslinked polymer (2-1) 6.00 2 Cyclomethicone 3.50 3 Dimethicone (5 cs) 2.00 4 Trimethylsiloxysilicate 1.50 5 Octyl methoxycinnamate 1.00 6 Phenoxyethanol 0.40 7 Tocophenol 0.10 8 Mica 39.60 9 Talc 24.00 10 Titanium oxide 20.00 11 Iron oxide 1.90

(69) The foundation was applied to ten panel members, and they evaluated the feeling thereof. They evaluated the two items: adhesiveness to the skin and sustainability. The results are shown in Table 2-6. In the table, the results are expressed as follows:

(70) Good: 5 or more out of 10 members evaluated the foundation as being better than the blank (unblended product); and

(71) Bad: less than 5 out of 10 members evaluated the foundation as being better than the blank (unblended product).

(72) As shown in Table 2-6, the foundation (Example 2-5) containing the product according to the invention had better adhesiveness to the skin and better sustainability than the blank (unblended product). On the other hand, the blank (unblended product) had poor adhesiveness to the skin and poor sustainability.

(73) TABLE-US-00008 TABLE 2-6 Adhesiveness Sustain- Example Compound to skin ability Example 2-5 VP crosslinked polymer (2-1) Good Good Blank Free from Bad Bad VP crosslinked polymer (2-1)

<Example 2-6 and Comparative Examples 2-3 and 2-4> Testing for Deodorizing Properties for Diacetyl

(74) Two glass lidded Petri dishes (inner diameter: 27 mm) were prepared. Then, 0.50 g of the VP crosslinked polymer (2-4) obtained in Example 2-4 was weighed into one Petri dish. In addition, 0.50 g of polyethylene glycol 20000 (hereinafter, also referred to as PEG, Wako Pure Chemical Industries, Ltd.) was placed on the other Petri dish and an empty Petri dish as a blank was prepared as Comparative Examples 2-3 and 2-4, respectively.

(75) The three Petri dishes were covered and completely enclosed in sampling bags with a stopcock (Tedlar bag, GL Sciences Inc., volume: 3 L, shape: AAK) by heat-sealing. The sampling bags were evacuated, and 2 L of nitrogen gas was introduced into each bag, followed by introduction of 5 mL of diacetyl-containing nitrogen gas thereinto using a gas-tight syringe. The Petri dishes with a lid removed were allowed to stand for two hours in the respective bags. Then, a 100-mL portion of the gas was drawn three times from each bag with a gas sampler (Model: GV-100S, Gastec Corporation), and the reduction rates of diacetyl concentrations were compared using a gas detector tube (No. 92 for acetaldehyde, Gastec Corporation). The measured values were converted to diacetyl concentrations using a calibrated scale described in the manual of the detector tube.

(76) The reduction rates of diacetyl were calculated using the following equation.
Reduction rate (%)=(gas concentration of blank−gas concentration of sample) (gas concentration of blank)×100

(77) The results are shown in Table 2-7.

(78) TABLE-US-00009 TABLE 2-7 Measured value Reduction rate Sample (ppm) (%) Example 2-6 VP crosslinked 80 56 polymer (2-4) Comparative PEG 110 39 Example 2-3 Comparative Blank 180 0 Example 2-4

<Example 2-7 and Comparative Examples 2-5 and 2-6> Testing for Deodorizing Properties for Nonenal

(79) Two glass lidded Petri dishes (inner diameter: 27 mm) were prepared. Then, 0.50 g of the VP crosslinked polymer (2-4) obtained in Example 2-4 was weighed into one Petri dish. In addition, 0.50 g of PEG was placed on the other Petri dish and an empty Petri dish was prepared as a blank as Comparative Examples 2-5 and 2-6, respectively.

(80) The three Petri dishes were covered and completely enclosed in sampling bags with a stopcock (Tedlar bag, GL Sciences Inc., volume: 3 L, shape: AAK) by heat-sealing. The sampling bags were evacuated, and 0.5 L of nitrogen gas was introduced into each bag. Thereafter, 20 μL of a 10% ethanol solution of nonenal was introduced into each bag using a microsyringe. The Petri dishes with a lid removed were allowed to stand for two hours in the respective bags. Then, a 100-mL portion of the gas was drawn once from each bag with a gas sampler (Model: GV-100S, Gastec Corporation), and the concentrations of nonenal were measured using a gas detector tube (No. 91L for formaldehyde, Gastec Corporation). The reduction rates were calculated based on the actual value measured with the detector tube.

(81) The reduction rates of nonenal were calculated using the following equation.
Reduction rate (%)=(gas concentration of blank−gas concentration of sample) (gas concentration of blank)×100

(82) The results are shown in Table 2-8.

(83) TABLE-US-00010 TABLE 2-8 Measured value Reduction rate Sample (ppm) (%) Example 2-7 VP crosslinked 19.2 20 polymer (2-4) Comparative PEG 22.4 7 Example 2-5 Comparative Blank 24.0 0 Example 2-6

<Example 2-8 and Comparative Examples 2-7 and 2-8> Testing for Deodorizing Properties for Acetic Acid

(84) Two glass lidded Petri dishes (inner diameter: 27 mm) were prepared. Then, 0.50 g of the VP crosslinked polymer (2-4) obtained in Example 2-4 was weighed into one Petri dish. In addition, 0.50 g of PEG was placed on the other Petri dish and an empty Petri dish was prepared as a blank as Comparative Examples 2-8 and 2-9, respectively.

(85) The three Petri dishes were covered and completely enclosed in sampling bags with a stopcock (Tedlar bag, GL Sciences Inc., volume: 3 L, shape: AAK) by heat-sealing. The sampling bags were evacuated, and 2 L of nitrogen gas was introduced into each bag. Thereafter, 5 mL of acetic acid-containing air was introduced into each bag using a gas-tight syringe. The Petri dishes with a lid removed were allowed to stand for two hours in the respective bags. Then, a 100-mL portion of the gas was drawn once from each bag with a gas sampler (Model: GV-100S, Gastec Corporation), and the concentrations of acetic acid were measured using a gas detector tube (No. 81 for acetic acid, Gastec Corporation). The reduction rates were calculated based on the actual value measured with the detector tube.

(86) The reduction rates of acetic acid were calculated using the following equation.
Reduction rate (%)=(gas concentration of blank−gas concentration of sample)−(gas concentration of blank)×100

(87) The results are shown in Table 2-9.

(88) TABLE-US-00011 TABLE 2-9 Measured value Reduction rate Sample (ppm) (%) Example 2-8 VP crosslinked 8 74 polymer (2-4) Comparative PEG 21 32 Example 2-7 Comparative Blank 31 0 Example 2-8

<Example 2-9 and Comparative Examples 2-9 and 2-10> Testing for Deodorizing Properties for Ammonia

(89) Two glass lidded Petri dishes (inner diameter: 27 mm) were prepared. Then, 1.0 g of the VP crosslinked polymer (2-4) obtained in Example 2-4 was weighed into one Petri dish. In addition, 1.0 g of PEG was placed on the other Petri dish and an empty Petri dish was prepared as a blank as Comparative Examples 2-10 and 2-11, respectively.

(90) The three Petri dishes were covered and completely enclosed in sampling bags with a stopcock (Tedlar bag, GL Sciences Inc., volume: 3 L, shape: AAK) by heat-sealing. The sampling bags were evacuated, and 1 L of nitrogen gas was introduced into each bag. Thereafter, 0.37 g of an about 0.1% ammonia water was introduced into each bag using a disposable syringe. The Petri dishes with a lid removed were allowed to stand for two hours in the respective bags. Then, about 30-mL portion of the gas was drawn from each bag with a gas sampler (Model: GV-100S, Gastec Corporation), and the concentrations of ammonia were measured using a gas detector tube (No. 3 La for ammonia, Gastec Corporation). The measured values were corrected based on the scale length of the drawn gas in the gas sampler, and the reduction rates were determined.

(91) The reduction rates of ammonia were calculated using the following equation.
Reduction rate (%)=(gas concentration of blank−gas concentration of sample)−(gas concentration of blank)×100

(92) The results are shown in Table 2-10.

(93) TABLE-US-00012 TABLE 2-10 Measured value Reduction rate Sample (ppm) (%) Example 2-9 VP crosslinked 122 35 polymer (2-4) Comparative PEG 188 0 Example 2-9 Comparative Blank 188 0 Example 2-10

<Example 2-10 and Comparative Examples 2-11 and 2-12> Testing for Deodorizing Properties for Methyl Mercaptan

(94) Two glass lidded Petri dishes (inner diameter: 27 mm) were prepared. Then, 5.0 g of the VP crosslinked polymer (2-4) obtained in Example 2-4 was weighed into one Petri dish. In addition, 5.0 g of PEG was placed on the other Petri dish and an empty Petri dish was prepared as a blank as Comparative Examples 2-11 and 2-12, respectively.

(95) The three Petri dishes were covered and completely enclosed in sampling bags with a stopcock (Tedlar bag, GL Sciences Inc., volume: 3 L, shape: AAK) by heat-sealing. The sampling bags were evacuated, and 1 L of nitrogen gas was introduced into each bag. Thereafter, 0.40 g of about 0.06% methyl mercaptan sodium water was introduced into each bag using a disposable syringe. The Petri dishes with a lid removed were allowed to stand for two hours in the respective bags. Then, a 100-mL portion of the gas was drawn once from each bag with a gas sampler (Model: GV-100S, Gastec Corporation), and the concentrations of methyl mercaptan were measured using a gas detector tube (No. 71 for methyl mercaptan, Gastec Corporation). The reduction rates were calculated based on the actual value measured with the detector tube.

(96) The reduction rates of methyl mercaptan were calculated using the following equation.
Reduction rate (%)=(gas concentration of blank−gas concentration of sample)−(gas concentration of blank)×100

(97) The results are shown in Table 2-11.

(98) TABLE-US-00013 TABLE 2-11 Measured value Reduction rate Sample (ppm) (%) Example 2-10 VP crosslinked 50 21 polymer (2-4) Comparative PEG 63 0 Example 2-11 Comparative Blank 63 0 Example 2-12

(99) Table 2-12 shows the evaluation results of the testings for deodorizing properties in Examples 2-6 to 2-10 and Comparative Examples 2-3 to 2-12.

(100) TABLE-US-00014 TABLE 2-12 Reduction rate (%) Diace- Ace- Ammo- Methyl Sample tyl Nonenal tate nia mercaptan Example VP cross- 56 20 74 35 21 linked polymer (2-4) Comparative PEG 39 7 32 0 0 Example Blank 0 0 0 0 0

(101) These results demonstrate that the VP crosslinked polymer has excellent deodorizing properties for diacetyl, nonenal, acetic acid, ammonia, and methyl mercaptan.

<Evaluation Example 2-3> Evaluation of Concentration-Viscosity

(102) Dispersions having different concentrations of the VP crosslinked polymer (2-2) obtained in Example 2-2 were prepared, and the viscosities at the respective concentrations were measured. As comparative samples, polyvinylpyrrolidone (polyvinylpyrrolidone K-90, Nippon Shokubai Co., Ltd., K value (catalog value): 88.0 to 96.0, hereinafter, also referred to as PVP) was used. The measurements were performed in the following way. The results are shown in Tables 2-13 and 2-14.

(103) (Evaluation Method)

(104) Dispersions of the VP crosslinked polymer (2-2) having a concentration of 1, 2, 3, 4, or 5 mass % were prepared using deionized water (conductivity: 10 μS/cm or lower), ethanol, or ethylene glycol as a solvent (room temperature (temperature: 23±2° C.), prepared by stirring for 16 hours under atmospheric pressure).

(105) Separately, solutions of PVP having a concentration of 5, 10, or 20 mass % were prepared using deionized water, ethanol, or ethylene glycol as a solvent (dissolution was performed using a rotary shaker at room temperature). The temperatures of the solutions were set at 25° C., and the viscosities of the solutions were measured using a B-type viscometer (Model: BM, Toki Sangyo Co., Ltd.).

(106) The viscosities of the VP crosslinked polymer (2-2) solutions rapidly increased at the time when the solutions reached the saturation of absorption. The solution (5%) having a rapidly increased viscosity was found to have thixotropy. The use of a dispersion medium having a large molecular size and a high viscosity such as ethylene glycol increased the viscosities of the dispersions of the VP crosslinked polymer (2-2). Further, the VP crosslinked polymer (2-2) required a smaller amount thereof to increase the viscosity than PVP (uncrosslinked).

(107) TABLE-US-00015 TABLE 2-13 Deionized water Ethanol Ethylene glycol Rotation Rotation Rotation Concentration Rotor speed Viscosity Rotor speed Viscosity Rotor speed Viscosity (mass %) No. (rpm) (mPa .Math. s) No. (rpm) (mPa .Math. s) No. (rpm) (mPa .Math. s) VP crosslinked 1 2 60 9 2 60 7 2 60 57 polymer (2-2) 2 2 60 14 2 60 14 4 60 360 3 2 30 112 2 30 86 4 30 3500 4 4 60 600 4 30 680 4 6 79900 5 4 30 7480 4 12 13000 PVP 5 2 60 66 2 60 68 4 60 1280 10 4 60 570 4 60 500 4 60 3690 20 4 30 13540 4 12 9500

(108) TABLE-US-00016 TABLE 2-14 Deionized water Concentration Rotation speed Viscosity (mass %) Rotor No. (rpm) (mPa .Math. s) VP crosslinked polymer 5 4 30 7480 (2-2) 4 60 3920
<Measurement of Average Particle Sizes of Crosslinked Polymers (3-1) and (3-2)>

(109) Sieves were combined from the top in descending order of mesh size. The crosslinked polymer was placed on the top sieve, and the sieves were shaken using an electromagnetic vibration small sieving machine (Model: M-2, Tsutsui Scientific Instruments Co., Ltd.) at 60 Hz for 10 minutes. At this time, the temperature was 23° C., and the humidity was 50%. The mass of the mixture left on each sieve was measured. The mesh size of each sieve and the mass ratio (percentage of remaining particles) R of particles that did not pass through the each sieve (the sum of the particles left on the certain sieve and the particles left on the sieves having a larger mesh size than the certain sieve) to all particles were plotted on a single logarithmic graph (horizontal axis: particle size (logarithmic scale), vertical axis: percentage of remaining particles). The particle size corresponding to R=50% was determined as the average particle size.

Production Example 3-1

(110) A desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) was charged with 130.0 parts of N-vinylpyrrolidone (hereinafter, also referred to as VP, Nippon Shokubai Co., Ltd.), 0.52 parts (0.18 mol % relative to VP) of triallyl cyanurate (hereinafter, also referred to as CTA) as a crosslinking agent, and 304.6 parts of deionized water. Subsequently, the kneader was purged with nitrogen at 100 mL/min for 30 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 1.96 parts (0.25 g per 1 mol of the sum of VP and CTA used) of a 15 mass % aqueous solution of 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (hereinafter, also referred to as “VA-044”) as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, 65.0 parts of a 1 mass % aqueous solution of malonic acid was added over three minutes, followed by stirring at 90° C. for 60 minutes. In addition, 32.5 parts of a 2 mass % aqueous solution of diethanolamine was added over three minutes, followed by stirring for 30 minutes. The resulting gel was dried at 120° C. for two hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used) to obtain a dried VP crosslinked polymer. Then, the crosslinked polymer was ground using a grinder and classified using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The powder that passed through the 500 μm-mesh sieve and left on the 250 μm-mesh sieve was obtained as a particulate VP crosslinked polymer (VP crosslinked polymer (3-1) of the invention). The average particle size of the VP crosslinked polymer (3-1) was 340 μm determined by the above-described method. The 50% cumulative value was 347 μm measured using a dry particle size distribution analyzer (Model: MT3100II, dry type, MicrotracBEL Corp.). The following describes the measurement conditions.

(111) <Measurement Conditions>

(112) Dry laser diffraction scattering method

(113) Measurement time: 10 seconds

(114) Dispersion pressure: None

(115) Particle transmission: Transmit

(116) Particle refractive index: 1.60

(117) Particle shape: Non-spherical

(118) Medium name: Air

(119) Medium refractive index: 1.00

(120) Measurement range: 0.7 to 1000 μm

Production Example 3-2

(121) A desktop kneader (Model: PNV-5H, Chuorika Co., Ltd.) was charged with 1000.0 parts of VP, 15.0 parts (0.65 mol % relative to VP) of pentaerythritol triallyl ether (trade name: neoallyl P-30M, Daiso Co., Ltd., the pH was adjusted to 6 or higher using diethanolamine) as a crosslinkable monomer, and 2368.33 parts of deionized water. Subsequently, the kneader was purged with nitrogen at 400 mL/min for 40 minutes. Then, nitrogen was introduced at 30 mL/min, and the temperature was increased to 56° C. After the temperature of the liquid was stabilized at 56° C., 47.37 parts (0.78 g per 1 mol of the sum of VP and pentaerythritol triallyl ether used) of a 15 mass % aqueous solution of 2,2′-azobis(2-methylpropionamidine) dihydrochloride (hereinafter, also referred to as “V-50”) as an initiator was added to start polymerization. A gel formed by the polymerization reaction was aged at 90° C. for 60 minutes while it was pulverized with the rotating blade of the kneader to complete the polymerization. Subsequently, 500.0 parts of a 1.4 mass % aqueous solution of malonic acid was added over three minutes, followed by stirring at 90° C. for 60 minutes. In addition, 250.0 parts of a 2.8 mass % aqueous solution of diethanolamine was added over three minutes, followed by stirring for 30 minutes. The resulting gel was dried at 120° C. for three hours (precision constant temperature oven, Model: DF42, Yamato Scientific Co., Ltd., maximum opening degree, two stainless steel vats each having external dimensions of 232×297×50 H (mm) were used, eight stainless steel vats each having external dimensions of 206×267×40 H (mm) were used) to obtain a dried VP crosslinked polymer. Then, the crosslinked polymer was ground using a grinder and classified using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The powder that passed through the 500 μm-mesh sieve and left on the 250 μm-mesh sieve was obtained as a particulate VP crosslinked polymer (VP crosslinked polymer (3-2) of the invention).

(122) The average particle size of the VP crosslinked polymer (3-2) was 324 μm determined by the above-described method.

Comparative Production Example 3-1

(123) First, 50 parts of polyethylene glycol 20000 was placed in a 50-ml glass separable flask and liquefied by stirring at 128° C. The stirring was performed at 50 rpm from the beginning to the end. After confirming the liquefaction, 2.5 parts of CTA was added to the flask as a crosslinking agent, and the contents were stirred for five minutes. Then, 0.12 parts of perbutyl 1-75 (NOF Corp.) was added thereto as an initiator, and the contents were continuously stirred at 128° C. for three hours. The resulting gel was cooled to 80° C., followed by pulverization using a desktop kneader (Model: PNV-1H, Chuorika Co., Ltd.) to obtain a polyethylene oxide crosslinked polymer. Then, the crosslinked polymer was ground using a grinder and classified using JIS standard 250 μm-mesh and 500 μm-mesh sieves. The powder that passed through the 500 μm-mesh sieve and left on the 250 μm-mesh sieve was obtained as a particulate polyethylene oxide crosslinked polymer (comparative crosslinked polymer (3-1) of the invention).

Examples 3-1 and 3-2 and Comparative Example 3-1

(124) The VP crosslinked polymers (3-1) and (3-2) obtained in Production Examples 3-1 and 3-2 and the comparative crosslinked polymer (2-2) obtained in Comparative Production Example 2-2 were evaluated as Examples 3-1 and 3-2 and Comparative Example 3-1, respectively.

(125) (Evaluation Method)

(126) First, 0.1 g of a crosslinked polymer was put into a 4 cm×5 cm nonwoven fabric tea bag, and the tea bag was heat-sealed. The tea bag was placed in a 50 mL (specified volume) glass screw tube. These operations were performed in a room at a temperature of 23±2° C., a relative humidity of 50±5%, and atmospheric pressure. To the screw tube containing the tea bag was added 2 g of ink (BCI-351 (dye BK, C, M, or Y) or BCI-350 (PGBK (pigment BK)), Canon Inc.) at room temperature (temperature: 23±2° C.). The screw tube was allowed to stand for eight hours at room temperature (temperature: 23±2° C.) and atmospheric pressure. Thereafter, the inside of the screw tube was observed to evaluate the presence or absence of residual liquid (fluid liquid). The results are shown in Table 3-1. The components of the inks are shown in Table 3-2. In Table 3-1, good means the absence of residual liquid, and bad means the presence of residual liquid. The results demonstrate that the VP crosslinked polymers (3-1) and (3-2) according to the invention are superior to the comparative crosslinked polymer (2-2) in that the VP crosslinked polymers (3-1) and (3-2) are capable of absorbing many types of inks without leaving the ink.

(127) TABLE-US-00017 TABLE 3-1 Evaluation of presence or absence of residual liquid Comparative Example 3-1 Example 3-1 Example 3-2 Comparative VP crosslinked VP crosslinked crosslinked Solution polymer (3-1) polymer (3-2) polymer (2-2) Pigment ink BK Good Good Good Dye ink BK Good Good Bad Dye ink C Good Good Good Dye ink M Good Good Good Dye ink Y Good Good Bad

(128) TABLE-US-00018 TABLE 3-2 Amount Ink Component (mass %) Pigment BK Glycerol 10 to 15 Glycol 5 to 10 Lactam 5 to 10 Water 60 to 80 Dye BK Glycerol 5 to 10 Glycol 15 to 20 Lactam 5 to 10 Water 60 to 80 Dye C Glycerol 5 to 10 Urea compound 5 to 10 Copper phthalocyanine compound 1 to 5 Copper phthalocyanine compound 1 to 5 Glycol 10 to 15 Water 60 to 80 Dye M Urea compound 5 to 10 Glycerol 1 to 5 Pyridine azo compound 1 to 5 Water 60 to 80 Dye Y Glycerol 5 to 10 Urea compound 5 to 10 Thiadiazole azo compound 1 to 5 Glycol 10 to 15 Water 60 to 80