Alkyl-modified carboxyl group-containing copolymer, thickener containing said copolymer, and method for preparing said copolymer

Abstract

Provided is an alkyl-modified carboxyl group-containing copolymer with which a neutralized viscous liquid can be prepared which has excellent dispersibility in water, has a viscosity that does not change greatly regardless of addition of an electrolyte, and has high transparency in the presence of an electrolyte. This alkyl-modified carboxyl group-containing copolymer contains: 100 parts by mass of a (meth)acrylic acid; 1.5-4.5 parts by mass of a (meth)acrylic acid alkyl ester, in which an alkyl group has 18-24 carbon atoms; and 0-0.1 parts by mass of a compound having two or more ethylenically unsaturated groups, wherein the copolymer contains 1.5-4.5 parts by mass of a nonionic surfactant.

Claims

1. An alkyl-modified carboxyl group-containing copolymer being a copolymer of 100 parts by mass of a (meth)acrylic acid, 1.5 to 4.5 parts by mass of an alkyl (meth)acrylate ester having an alkyl group having 18 to 24 carbon atoms, and 0 to 0.1 parts by mass of a compound having two or more ethylenically unsaturated groups, the alkyl-modified carboxyl group-containing copolymer comprising 1.5 to 4.5 parts by mass of a nonionic surfactant wherein the nonionic surfactant is composed of a hydrophobic moiety and a hydrophilic moiety, and wherein the hydrophobic moiety is a type selected from the group consisting of a polyhydric alcohol fatty acid ester and an addition polymer of a hydroxy fatty acid, and wherein the nonionic surfactant has a hydrophilic-lipophilic balance (HLB) of 5 to 8.

2. The alkyl-modified carboxyl group-containing copolymer according to claim 1, wherein a light transmittance X of a 1% by mass neutralized viscous liquid of the alkyl-modified carboxyl group-containing copolymer is 90% or more.

3. The alkyl-modified carboxyl group-containing copolymer according to claim 1, wherein a light transmittance Y of an electrolyte-containing 1% neutralized viscous liquid prepared by adding 1 part by mass of sodium chloride to 100 parts by mass of the 1% by mass neutralized viscous liquid of the alkyl-modified carboxyl group-containing copolymer is 90% or more.

4. The alkyl-modified carboxyl group-containing copolymer according to claim 1, wherein a viscosity A of the 1% by mass neutralized viscous liquid of the alkyl-modified carboxyl group-containing copolymer is 5,000 mPa.Math.s or more at 25° C.

5. The alkyl-modified carboxyl group-containing copolymer according to claim 1, wherein a viscosity ratio (viscosity B/viscosity A) of a viscosity B of an electrolyte-containing 1% neutralized viscous liquid, prepared by adding 1 part by mass of sodium chloride to 100 parts by mass of the 1% by mass neutralized viscous liquid of the alkyl-modified carboxyl group-containing copolymer, to the viscosity A of the 1% by mass neutralized viscous liquid is in a range of 0.5 to 2.0 at 25° C.

6. The alkyl-modified carboxyl group-containing copolymer according to claim 1, wherein an absolute value |viscosity A-viscosity B| of a difference between the viscosity A of the 1% by mass neutralized viscous liquid of the alkyl-modified carboxyl group-containing copolymer and the viscosity B of the electrolyte-containing 1% neutralized viscous liquid prepared by adding 1 part by mass of sodium chloride to 100 parts by mass of the 1% by mass neutralized viscous liquid is 10,000 mPa.Math.s or less.

7. The alkyl-modified carboxyl group-containing copolymer according to claim 1, wherein the compound having two or more ethylenically unsaturated groups is at least one selected from the group consisting of pentaerythritol polyallyl ether, diethylene glycol diallyl ether, polyethylene glycol allyl ether, and polyallyl saccharose.

8. The alkyl-modified carboxyl group-containing copolymer according to claim 1, being in a form of fine particles.

9. A thickener comprising the alkyl-modified carboxyl group-containing copolymer according to claim 1.

10. A method for preparing the alkyl-modified carboxyl group-containing copolymer according to claim 1, the method comprising copolymerizing a (meth)acrylic acid, an alkyl (meth)acrylate ester having an alkyl group having 18 to 24 carbon atoms, and optionally a compound having two or more ethylenically unsaturated groups in the presence of a nonionic surfactant.

Description

EXAMPLES

(1) Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, the present invention is not limited to the examples.

Example 1

(2) A 500-mL four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a condenser was charged with 45 g of acrylic acid, 1.35 g of BLEMMER VMA70 (manufactured by NOF Corporation: a mixture containing 10 to 20 parts by mass of stearyl methacrylate, 10 to 20 parts by mass of eicosanyl methacrylate, 59 to 80 parts by mass of behenyl methacrylate, and 1% by mass or less of tetracosanyl methacrylate) as an alkyl (meth)acrylate ester having an alkyl group having 18 to 24 carbon atoms, 0.116 g of 2,2′-azobismethylisobutyrate as a radical polymerization initiator, and 230.9 g of normal-hexane as a reaction solvent. Subsequently, the solution was homogeneously mixed while stirring, and a nitrogen gas was then blown into the solution in order to remove oxygen existing in the upper spatial region of the reaction vessel (four-necked flask), raw materials and the reaction solvents. Next, the solution was heated to 60 to 65° C. in a nitrogen atmosphere. 2 hours after the temperature of the solution reached 60° C., 0.9 g of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) as the nonionic surfactant was charged into the reaction vessel. Thereafter, the temperature of the solution was maintained at 60 to 65° C. for 3 hours after reaching 60° C. Thereafter, the formed slurry was heated to 100° C. to distill off normal-hexane, further dried for 8 hours by setting the set temperature of a heating device to 115° C. and setting the set pressure of a decompression device to 10 mmHg, to thereby give 41 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Example 2

(3) The same procedures as in Example 1 were carried out, except for adding 0.0045 g of pentaerythritol polyallyl ether as a compound having at least two ethylenically unsaturated groups at the time of preparation of the raw material before heating, to give 43 g of white fine particles of an alkyl-modified carboxy group-containing copolymer.

Example 3

(4) The same procedures as in Example 2 were carried out, except for changing the amount of BLEMMER VMA70 (manufactured by NOF Corporation: a mixture containing 10 to 20 parts by mass of stearyl methacrylate, 10 to 20 parts by mass of eicosanyl methacrylate, 59 to 80 parts by mass of behenyl methacrylate, and 1% by mass or less of tetracosanyl methacrylate) used to 1.575 g and changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) used to 1.575 g, to give 42 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Example 4

(5) The same procedures as in Example 2 were carried out, except for using 1.35 g of polyoxyethylene (30) hydrogenated castor oil triisostearate (EMALEX RWIS-330 from Nihon Emulsion Co., Ltd.) instead of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer 8246 from Croda), to give 43 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Example 5

(6) The same procedures as in Example 2 were carried out, except for using 1.35 g of polyoxyethylene (20) hydrogenated castor oil triisostearate (EMALEX RWIS-320 from Nihon Emulsion Co., Ltd.) instead of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda), to give 43 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Example 6

(7) The same procedures as in Example 2 were carried out, except for changing the amount of BLEMMER VMA70 (manufactured by NOF Corporation: a mixture containing 10 to 20 parts by mass of stearyl methacrylate, 10 to 20 parts by mass of eicosanyl methacrylate, 59 to 80 parts by mass of behenyl methacrylate, and 1% by mass or less of tetracosanyl methacrylate) used to 1.125 g and changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) used to 1.800 g, to give 42 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Example 7

(8) The same procedures as in Example 1 were carried out, except for changing the amount of BLEMMER VMA70 (manufactured by NOF Corporation: a mixture containing 10 to 20 parts by mass of stearyl methacrylate, 10 to 20 parts by mass of eicosanyl methacrylate, 59 to 80 parts by mass of behenyl methacrylate, and 1% by mass or less of tetracosanyl methacrylate) used to 1.800 g and changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer 9246 from Croda) used to 0.675 g, to give 41 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Comparative Example 1

(9) The same procedures as in Example 2 were carried out, except for changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) used to 0.450 g, to give 40 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Comparative Example 2

(10) The same procedures as in Example 2 were carried out, except for changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) used to 2.250 g, to give 43 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Comparative Example 3

(11) The same procedures as in Example 2 were carried out, except for changing the amount of BLEMMER VMA70 (manufactured by NOF Corporation: a mixture containing 10 to 20 parts by mass of stearyl methacrylate, 10 to 20 parts by mass of eicosanyl methacrylate, 59 to 80 parts by mass of behenyl methacrylate, and 1% by mass or less of tetracosanyl methacrylate) used to 0.900 g, changing the amount of pentaerythritol polyallyl ether used as a compound having at least two ethylenically unsaturated groups to 0.068 g, and changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) used to 1.350 g, to give 43 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Comparative Example 4

(12) The same procedures as in Example 2 were carried out, except for changing the amount of BLEMMER VMA70 (manufactured by NOF Corporation: a mixture containing 10 to 20 parts by mass of stearyl methacrylate, 10 to 20 parts by mass of eicosanyl methacrylate, 59 to 80 parts by mass of behenyl methacrylate, and 1% by mass or less of tetracosanyl methacrylate) used to 2.475 g and changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) used to 1.350 g, to give 43 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

Comparative Example 5

(13) The same procedures as in Example 2 were carried out, except for changing the amount of BLEMMER VMA70 (manufactured by NOF Corporation: a mixture containing 10 to 20 parts by mass of stearyl methacrylate, 10 to 20 parts by mass of eicosanyl methacrylate, 59 to 80 parts by mass of behenyl methacrylate, and 1% by mass or less of tetracosanyl methacrylate) used to 0.450 g and changing the amount of a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda) used to 1.350 g, to give 43 g of white fine particles of an alkyl-modified carboxyl group-containing copolymer.

(14) <Evaluation>

(15) Each alkyl-modified carboxyl group-containing copolymer obtained above was evaluated by the following methods. The results are shown in Table 1.

(16) (1) Dispersibility in Water

(17) 495 g of distilled water at 25° C. was added to a glass beaker having a diameter of 11 cm and a capacity of 1000 mL, and the distilled water was stirred at 1000 rpm using a stirrer having three blades with a diameter of 3 cm. 5 g of each alkyl-modified carboxyl group-containing copolymer obtained above was gradually added to the continuously stirred water, and the time until the copolymer was uniformly dispersed without any lumps was visually confirmed. In order to prevent overlooking of the alkyl-modified carboxyl group-containing copolymer before the copolymer was thoroughly dispersed, the dispersion was passed through a filter cloth having an opening of 142 μm. When a block of the alkyl-modified carboxyl group-containing copolymer was confirmed on the filter cloth, it was judged that the alkyl-modified carboxyl group-containing copolymer was not uniformly dispersed, and the measurement was performed again from the beginning. If the time until uniform dispersion is 30 minutes or less, uniform dispersibility in water can be evaluated as excellent.

(18) (2) Preparation of 1% by Mass Neutralized Viscous Liquid

(19) 283 g of each alkyl-modified carboxyl group-containing copolymer dispersion obtained above was weighed into a 500 mL beaker and added with 17 g of 6% by mass sodium hydroxide while stirring to give a 1% by mass neutralized viscous liquid having a pH of 6.5 to 7.5. The 1% by mass neutralized viscous liquid was allowed to stand in a constant temperature water bath at 25° C. until the temperature reached 25° C., and used as an evaluation sample.

(20) (3) Preparation of Electrolyte-Containing 1% Neutralized Viscous Liquid.

(21) In the same manner as in “(2) Preparation of 1% by mass neutralized viscous liquid”, each 1% by mass neutralized viscous liquid was obtained. Next, while continuing stirring of the 1% by mass neutralized viscous liquid, 3 g of sodium chloride was added, and the stirring was continued until the viscous liquid became uniform, thereby obtaining an electrolyte-containing 1% neutralized viscous liquid containing 1% by mass of sodium chloride. The electrolyte-containing 1% neutralized viscous liquid was allowed to stand in a constant temperature water bath at 25° C. until the temperature reached 25° C., and used as an evaluation sample.

(22) (4) Viscosity Measurement

(23) The viscosity after 1 minute for each of the evaluation samples obtained above was measured at 25° C. using a rotary viscometer with a rotational speed of a spindle rotor No. 6 of 20 rotations per minute. The viscosity A (mPa.Math.s) of the 1% by mass neutralized viscous liquid, the viscosity B (mPa.Math.s) of the electrolyte-containing 1% neutralized viscous liquid, the viscosity ratio (viscosity B/viscosity A), and the absolute value |viscosity A-viscosity B| (mPa.Math.s) of the viscosity difference are shown in Table 1.

(24) (5) Light Transmittance Measurement

(25) Each of the evaluation samples was defoamed by operation at 2000 rotations per minute for 20 minutes in a centrifugal separator, and then light transmittance was measured using a cell having an optical path length of 1 cm at a measurement wavelength of 425 nm. Usually, when the light transmittance is 90% or more, it can be said to be transparent visually. The light transmittance X (%) of the 1% by mass neutralized viscous liquid and the light transmittance V (%) of the electrolyte-containing 1% neutralized viscous liquid are shown in Table 1.

(26) TABLE-US-00001 TABLE 1 Com- Com- Com- Com- Com- parative parative parative parative parative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Component Unit ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 1 ple 2 ple 3 ple 4 ple 5 Acrylic acid Parts 100 100 100 100 100 100 100 00 100 100 100 100 by mass Alkyl Parts 3.0 3.0 3.5 3.0 3.0 2.5 4.0 3.0 3.0 2.0 5.5 1.0 (meth)acrylate by ester having an mass alkyl group having 18 to 24 carbon atoms Compound Parts 0 0.01 0.01 0.01 0.01 0.01 0 0.01 0.01 0.15 0.01 0.01 having by two or more mass ethylenically unsaturated groups Nonionic Type HYP246 HYP246 HYP246 RWIS- RWIS- HYP246 HYP246 HYP246 HYP246 HYP246 HYP246 HYP246 surfactant 330 320 Parts 2.0 2.0 3.5 3.0 3.0 4.0 1.5 1.0 5.0 3.0 3.0 3.0 by mass Viscosity A of mPa .Math. s 8,200 8,660 11,720 10,740 10,300 8,820 13,500 7,120 11,300 5,200 16,960 2,300 1% neutralized viscous liquid Viscosity B of mPa .Math. s 16,100 16,540 13,040 14,300 14,260 11,100 11,000 15,420 10,700 10,400 8,520 4,200 electrolyte- containing 1% neutralized viscous liquid Light % 96.1 96.1 97.5 100.0 100.0 96.2 95.2 96.7 95.7 95.0 95.6 95.6 transmittance X of 1% neutralized viscous liquid Light % 92.8 92.8 90.0 94.6 92.7 91.6 90.0 95.4 78.5 75.0 69.0 93.0 transmittance Y of electrolyte- containing 1% neutralized viscous liquid Viscosity ratio (viscosity 2.0 1.9 1.1 1.3 1.4 1.3 0.8 2.2 0.9 2.0 0.5 1.8 B/viscosity A) Absolute value mPa .Math. s 7,900 7,880 1,320 3,560 3,960 2,280 2,500 8,300 600 5,200 8,440 1,900 |viscosity A-viscosity B| of viscosity difference Dispersibility min 28 27 22 24 24 20 29 45 16 25 23 35 in water (time required for uniform dispersion in water)

(27) In Table 1, HYP246 refers to a block copolymer of 12-hydroxystearic acid and polyoxyethylene (Hypermer B246 from Croda). RWIS-330 refers to polyoxyethylene (30) hydrogenated castor oil triisostearate (EMALEX RWIS-330 from Nihon Emulsion Co., Ltd.). Similarly, RWIS-320 refers to polyoxyethylene (20) hydrogenated castor oil triisostearate (EMALEX RWIS-320 from Nihon Emulsion Co., Ltd.).