AQUEOUS INK COMPOSITION FOR DECORATIVE SHEET, PRINTED ITEM, AND LAMINATE FOR DECORATIVE SHEET

Abstract

An aqueous ink composition for a decorative sheet which can be printed without any disturbance of the printed portion caused by friction with the guide rollers or the like during printing, and also exhibits good permeability following immersion in an adhesive (impregnating solution) during post processing, and good adhesion to substrates following thermocompression bonding. Specifically, an aqueous ink composition for use on a base paper for a decorative sheet, the aqueous ink composition comprising a pigment and a water-soluble polyacrylamide resin (A).

Claims

1. An aqueous ink composition for use on a base paper for a decorative sheet, the aqueous ink composition comprising: a pigment, and a water-soluble polyacrylamide resin (A).

2. The aqueous ink composition according to claim 1, wherein a proportion of structural units derived from acrylamide within 100% by weight of the polyacrylamide resin (A) is 70% by weight or greater.

3. The aqueous ink composition according to claim 1, wherein a glass transition temperature of the polyacrylamide resin (A) is within a range from 80° C. to 200° C.

4. The aqueous ink composition according to claim 1, further comprising: a water-soluble resin (B), wherein the water-soluble resin (B) has a solid fraction acid value prior to neutralization of 50 to 350 mgKOH/g and a glass transition temperature within a range from 50° C. to 140° C., and is a different resin from the polyacrylamide resin (A).

5. The aqueous ink composition according to claim 1, further comprising: an emulsion resin (C), wherein the emulsion resin (C) has a minimum film-forming temperature (MFT) of 40° C. or lower.

6. The aqueous ink composition according to claim 1, further comprising: a water-soluble resin (B) and an emulsion resin (C), wherein the water-soluble resin (B) has a solid fraction acid value prior to neutralization of 50 to 350 mgKOH/g and a glass transition temperature within a range from 50° C. to 140° C., and is a different resin from the polyacrylamide resin (A), and the emulsion resin (C) has a minimum film-forming temperature (MFT) of 40° C. or lower.

7. The aqueous ink composition according to claim 4, wherein the water-soluble resin (B) is at least one resin selected from the group consisting of acrylic resins (b1) and styrene-acidic monomer copolymer resins (b2).

8. The aqueous ink composition according to claim 5, wherein the emulsion resin (C) is at least one resin selected from the group consisting of acrylic resins (c1), styrene-acrylic copolymer resins (c2), and urethane resins (c3).

9. The aqueous ink composition according to claim 4, wherein an amount of the water-soluble resin (B) is within a range from 0.1% by weight to 40% by weight relative to 100% by weight of the polyacrylamide resin (A).

10. The aqueous ink composition according to claim 5, wherein an amount of the emulsion resin (C) is within a range from 0.1% by weight to 40% by weight relative to 100% by weight of the polyacrylamide resin (A).

11. A printed item comprising: a base paper for a decorative sheet, and a printed layer formed on the base paper for a decorative sheet, wherein the printed layer is formed from the aqueous ink composition according to claim 1.

12. A laminate for a decorative sheet comprising: a substrate and a surface layer, wherein the surface layer is formed from a thermosetting compound and the printed item according to claim 11.

Description

EXAMPLES

[0142] The present invention is described below in further detail using a series of examples, but the present invention is in no way limited by these examples. Unless specifically noted otherwise, “parts” and “%” represent “parts by weight” and “% by weight” respectively.

[0143] Weight-average molecular weight values in the following examples were obtained by performing measurements under the conditions described below.

[0144] GPC main unit: LC1100 series, manufactured by Agilent Technologies, Inc.

[0145] Column: Shodex SB806MHQ, manufactured by Showa Denko K.K.

[0146] Eluent: N/15 phosphate buffer containing N/10 sodium nitrate (pH 3)

[0147] Flow rate: 1.0 ml/minute

[0148] Detector 1: Multi-angle light scattering detector DAWN, manufactured by Wyatt Technology Corporation

[0149] Detector 2: Differential refractive index detector RI-101, manufactured by Showa Denko K.K.

[0150] As described above, the glass transition temperature was determined using the FOX equation.

[0151] As mentioned above, the acid value was measured in accordance with JIS K0070.

Synthesis Example 1

[0152] In a 1-liter four-necked flask fitted with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 250 parts of water, 198 parts of a 50% aqueous solution of acrylamide (hereafter abbreviated as “Am”) and 2.0 parts of dimethylacrylamide (hereafter abbreviated as “DMMA”) were mixed and stirred. Subsequently, the temperature was raised to 60° C. under a nitrogen gas atmosphere, 0.3 parts of ammonium persulfate was added as a polymerization initiator, the polymerization was initiated, and the reaction temperature was raised to 90° C. An additional 0.3 parts of ammonium persulfate was then added, and when the viscosity at 25° C. reached 3,000 mPa.Math.s, 51 parts of water was added to obtain a polyacrylamide-based resin P1 having a solid fraction of 20%. The weight-average molecular weight was 3,000,000 and the Tg was 164.5° C.

Synthesis Examples 2 to 5

[0153] Using the raw materials and blend ratios shown in Table 1, polyacrylamide-based resins (P2 to P5) were obtained using the same procedure as that described in Synthesis Example 1. The abbreviations used for the raw materials are listed below.

[0154] Am: acrylamide

[0155] DMAA: dimethylacrylamide

[0156] IBXA: isobornyl acrylate

[0157] ADMA: adamantane methacrylate

[0158] BA: butyl acrylate

TABLE-US-00001 TABLE 1 Glass tran- Monomer sition Am IBXA DMAA ADMA BA tem- Weight- Glass transition temperature of per- average homopolymer (° C.) ature molecular 165 94 119 250 −55 Total (° C.) weight P1 99 1 100 164.5 3,000,000 P2 100 100 165.0 3,500,000 P3 90 10 100 156.7 2,800,000 P4 85 15 100 107.4 5,000,000 P5 75 5 20 100 175.2 3,000,000

Example 1

[0159] First, 35 parts of the polyacrylamide-based resin P1 obtained in the above Synthesis Example 1, 12 parts of C.I. Pigment Red 185 as a pigment, and 53 parts of water were mixed for 60 minutes using a Disper. The resulting mixed liquid was then dispersed for 30 minutes using a sand mill (media: glass beads of diameter 1.2 mm), yielding an aqueous ink composition S1.

Examples 2 to 18

[0160] Using the raw materials shown in Table 2-1, aqueous ink compositions S2 to S18 were obtained using the same procedure as that described for Example 1.

[0161] The abbreviations used for the raw materials shown in Table 2-1 are listed below. [0162] Joncryl HPD-96J: manufactured by BASF Corporation, a styrene-acrylic acid-based resin aqueous solution neutralized with alkaline water, NV 34% aqueous solution, weight-average molecular weight: 17,000, Tg: 102° C., solid fraction acid value: 240 mgKOH/g, pH: 8.5 [0163] Joncryl JDX-6180: manufactured by BASF Corporation, a styrene-acrylic acid-based resin aqueous solution neutralized with alkaline water, NV 27% aqueous solution, weight-average molecular weight: 14,000, Tg: 134° C., solid fraction acid value: 230 mgKOH/g, pH: 8.5 [0164] Joncryl JDX-6500: manufactured by BASF Corporation, an acrylic-based resin aqueous solution neutralized with alkaline water, NV 29.5% aqueous solution, weight-average molecular weight: 10,000, Tg: 65° C., solid fraction acid value: 85 mgKOH/g, pH: 7.5 [0165] Joncryl 352D: a styrene-acrylic-based resin emulsion, NV 45% aqueous solution, weight-average molecular weight: 250,000, minimum film-forming temperature: 10° C., Tg: 56° C., solid fraction acid value: 51 mgKOH/g, pH: 8.3 [0166] Joncryl 775: a styrene-acrylic-based resin emulsion, NV 45% aqueous solution, weight-average molecular weight: 300,000, minimum film-forming temperature: 15° C., Tg: 37° C., solid fraction acid value: 55 mgKOH/g, pH: 8.3 [0167] EK-108: manufactured by Saiden Chemical Industry Co., Ltd., an acrylic-based resin emulsion, NV 35% aqueous solution, minimum film-forming temperature: 38° C., Tg: 56° C., pH: 8.0 [0168] Superflex 150: manufactured by DKS Co., Ltd., a urethane (using both polyether and polyester) based resin emulsion, NV 30% aqueous solution, minimum film-forming temperature: 5° C., Tg: 40° C., pH: 9.0

Comparative Examples 1 to 10

[0169] Using the raw materials shown in Table 2-2, aqueous ink compositions T1 to T10 were obtained using the same procedure as that described for Example 1.

[0170] The abbreviations used for the raw materials shown in Table 2-2 are listed below. [0171] Urearno W321: a polyether-based water-soluble urethane resin (NV 33%) [0172] Plascoat Z-565: manufactured by GOO Chemical Co., Ltd., a water-soluble polyester resin (NV 25%) [0173] Super Ester NS-121: a rosin emulsion (NV 50%) [0174] Urearno KL-593: manufactured by Arakawa Chemical Industries, Ltd., an oil-based polyurethane resin (ether-ester-based) (NV 35%) in the form of an ethyl acetate/isopropanol (IPA) solution

TABLE-US-00002 TABLE 2-1 Example 1 2 3 4 5 6 7 8 9 Ink name Resin type S1 S2 S3 S4 S5 S6 S7 S8 S9 Polyacrylamide P1 polyacrylamide-based 8.0 resin (A) P2 polyacrylamide-based 8.0 7.0 7.0 7.0 7.0 (solid fraction) P3 polyacrylamide-based 8.0 P4 polyacrylamide-based 8.0 P5 polyacrylamide-based 8.0 Water-soluble Joncryl HPD-96J styrene/acrylic acid-based 1.0 resin (B) Joncryl JDX-6180 styrene/acrylic acid-based 1.0 (solid fraction) Joncryl JDX-6500 acrylic-based 1.0 Emulsion resin Joncryl 352D styrene/acrylic-based 1.0 (C) Joncryl 775 styrene/acrylic-based (solid fraction) EK-108 acrylic-based Superflex 150 urethane-based Pigment C.I. Pigment — 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Red 185 Medium Water — 82.0 82.0 82.0 82.0 82.0 82.0 82.0 82.0 82.0 Ink total — 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Solid fraction total 18.0 18.0 18.0 18.0 18.0 18.0 18.0 18.0 18.0 Resin A solid fraction % within 44.4 44.4 44.4 44.4 44.4 38.9 38.9 38.9 38.9 ink solid fraction Resin B/Resin A solid fraction % — 0.0 0.0 0.0 0.0 0.0 14.3 14.3 14.3 0.0 Resin C/Resin A solid fraction % — 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 14.3 Example 10 11 12 13 14 15 16 17 18 Ink name Resin type S10 S11 S12 S13 S14 S15 S16 S17 S18 Polyacrylamide P1 polyacrylamide-based 7.0 7.0 resin (A) P2 polyacrylamide-based 7.0 7.0 7.0 15.0 4.0 15.0 4.0 (solid fraction) P3 polyacrylamide-based P4 polyacrylamide-based P5 polyacrylamide-based Water-soluble Joncryl HPD-96J styrene/acrylic acid-based 0.2 1.5 1.0 1.0 resin (B) Joncryl JDX-6180 styrene/acrylic acid-based (solid fraction) Joncryl JDX-6500 acrylic-based Emulsion resin Joncryl 352D styrene/acrylic-based 1.0 (C) Joncryl 775 styrene/acrylic-based 1.0 1.0 (solid fraction) EK-108 acrylic-based 1.0 0.2 1.5 1.0 Superflex 150 urethane-based 1.0 Pigment C.I. Pigment — 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Red 185 Medium Water — 82.0 82.0 82.0 74.8 84.5 82.0 84.5 82.0 81.0 Ink total — 100.0 100.0 100.0 100.0 100.0 107.2 100.0 101.0 101.0 Solid fraction total 18.0 18.0 18.0 25.2 15.5 25.2 15.5 19.0 20.0 Resin A solid fraction % within 38.9 38.9 38.9 59.5 25.8 59.5 25.8 36.8 35.0 ink solid fraction Resin B/Resin A solid fraction % — 0.0 0.0 0.0 1.3 37.5 0.0 0.0 14.3 14.3 Resin C/Resin A solid fraction % — 14.3 14.3 14.3 0.0 0.0 1.3 37.5 14.3 28.6

TABLE-US-00003 TABLE 2-2 Comparative Example 1 2 3 4 5 6 7 8 9 10 Ink name T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 Solid Styrene/acrylic-based Joncryl HPD-96J 8.0 3.5 3.5 3.5 fraction % aqueous solution Acrylic-based aqueous Joncryl JDX-6500 8.0 3.5 solution Acrylic-based emulsion EK-108 8.0 3.5 Urethane-based Urearno W321 8.0 3.5 (water/IPA solution) Polyester-based Plascoat Z-565 8.0 Rosin emulsion Super Ester NS-121 8.0 Urethane-based Urearno KL-593 8.0 (water/IPA solution) Pigment C.I. Pigment Red 185 10 10 10 10 10 10 10 10 10 10 Medium Ethyl acetate/IPA = 50:50 82 Water 82 82 82 82 82 82 83 83 83 Total 100 100 100 100 100 100 100 100 100 100 Solid fraction % in ink 18 18 18 18 18 18 18 17 17 17 Resin % within solid fraction 44 44 44 44 44 44 44 41 41 41

<Printing of Aqueous Ink Compositions>

Example 19

[0175] The aqueous ink composition S1 described above was diluted with a mixed aqueous solution (water:IPA=7:3) to achieve a viscosity of 16 seconds (25° C., Zahn cup No. 3), and a gravure printer fitted with a solid image printing plate having a laser plate depth of 30 um was used to print the ink composition onto a titanium paper (60 g/m.sup.2) at a printing speed of 50 m/min, thus obtaining a printed item SS1.

Examples 20 to 36

[0176] Using the same procedure as Example 19, the aqueous ink compositions S2 to S18 shown in Table 2-1 were used to obtain printed items SS2 to SS18 (Examples) respectively.

Comparative Examples 11 to 20

[0177] Using the same procedure as Example 19, the aqueous ink compositions T1 to T10 shown in Table 2-2 were used to obtain printed items TT1 to TT10 (Comparative Examples) respectively. In Comparative Example 17, a mixed solvent (ethyl acetate/IPA=50:50) was used instead of the mixed aqueous solution (water:IPA=7:3) to dilute the composition to achieve a viscosity of 16 seconds (25° C., Zahn cup No. 3), and printing was then performed in the same manner as described above.

[0178] For each of the aqueous ink compositions S1 to S18 (Examples) and T1 to T10 (Comparative Examples) and each of the printed items SS1 to SS18 (Examples) and TT1 to TT10 (Comparative Examples) obtained in Examples 1 to 36 and Comparative Examples 1 to 20, tests were performed to evaluate the melamine aqueous solution impregnability, the dry rubbing resistance, the wet rubbing resistance, the laminate blistering resistance, and the ink stability. The results of these evaluations are shown in Table 3-1 and Table 3-2.

<Thermosetting Resin Solution Impregnability>

[0179] For each of the printed items SS1 to SS18 (Examples) and TT1 to TT10 (Comparative Examples), a 10 cm×10 cm sample of the printed item was immersed for 30 seconds in 500 ml of a melamine resin solution (water-soluble methylol melamine (manufactured by Nippon Carbide Industries Co., Inc.)/water=50:50), and the surface area of the resulting impregnated portion (wet portion) was evaluated.

[0180] A: the printed portion was 100% impregnated

[0181] B: 95% or more of the printed portion was impregnated

[0182] C: at least 50% but less than 95% of the printed portion was impregnated

[0183] D: at least 30% but less than 50% of the printed portion was impregnated

[0184] E: no impregnation

[0185] Evaluations results of A or B indicate no problems from a practical perspective.

<Dry Rubbing Resistance>

[0186] Each of the printed items SS1 to SS18 (Examples) and TT1 to TT10 (Comparative Examples) was set in a Gakushin crockmeter, and was rubbed 5 times against a wood-free paper using a loading of 300 g. The level of scratching of the retrieved printed item was then evaluated visually against the following 5-grade scale.

[0187] A: no scratches at all

[0188] B: slight scratches on less than 10% of the printed portion

[0189] C: scratches visible on at least 10% but less than 30% of the printed portion

[0190] D: scratches visible on at least 30% but less than 50% of the printed portion

[0191] E: scratches across the entire printed portion

[0192] Evaluations results of A or B indicate no problems from a practical perspective.

<Wet Rubbing Resistance>

[0193] Each of the printed items SS1 to SS18 (Examples) and TT1 to TT10 (Comparative Examples) was set in a Gakushin crockmeter, and was rubbed 5 times against a water-containing cotton cloth using a loading of 100 g. The level of scratching of the retrieved printed item was then evaluated visually against the following 5-grade scale.

[0194] A: no scratches at all

[0195] B: slight scratches on less than 10% of the printed portion

[0196] C: scratches visible on at least 10% but less than 30% of the printed portion

[0197] D: scratches visible on at least 30% but less than 50% of the printed portion

[0198] E: scratches across the entire printed portion

[0199] Evaluations results of A or B indicate no problems from a practical perspective.

<Laminate Blistering Resistance>

[0200] Each of the printed items SS1 to SS18 (Examples) and TT1 to TT10 (Comparative Examples) was impregnated and then dried under the conditions described above, and was then placed on a sheet of a 9.0 mm particle board “Novopan” manufactured by Japan Novopan Industrial Co., Ltd. A laminate was then prepared by thermocompression bonding using a hot press machine at 35 kg/cm.sup.2 and 190° C., and the resulting laminate was evaluated for blistering (lifting of the printed item).

[0201] A: no lifting at all was observed across the printed portion

[0202] B: lifting visible across less than 10% of the printed portion

[0203] C: lifting visible across at least 10% but less than 30% of the printed portion

[0204] D: lifting visible across at least 30% but less than 50% of the printed portion

[0205] E: bonding did not occur

[0206] Evaluations results of A or B indicate no problems from a practical perspective.

<Ink Stability>

[0207] Each of the aqueous ink compositions S1 to S18 (Examples) and T1 to T10 (Comparative Examples) and each of the printed items SS1 to SS18 (Examples) and TT1 to TT10 (Comparative Examples) was stored for one week in an oven at 50° C., and the stability over time was evaluated. Measurements were performed using a Zahn cup #4 manufactured by Rigo Co., Ltd., at a liquid temperature of 25° C., and the change in viscosity was evaluated.

[0208] A: no change in viscosity observed over time

[0209] B: increase in viscosity over time of less than 5 seconds

[0210] C: increase in viscosity over time of at least 5 seconds but less than 20 seconds

[0211] D: increase in viscosity over time of at least 20 seconds but less than 40 seconds

[0212] E: composition gelled over time

[0213] Evaluations results of A or B indicate no problems from a practical perspective.

TABLE-US-00004 TABLE 3-1 Example 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Ink name S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 Printed item SS1 SS2 SS3 SS4 SS5 SS6 SS7 SS8 SS9 SS10 SS11 SS12 SS13 SS14 SS15 SS16 SS17 SS18 Melamine aqueous A A A A A A A A A A A A A A A A A A solution impregnability Dry rubbing B B B B B A A A B B B B B A B A A A resistance Wet rubbing B A B B B B B B A A A B B B B B A A resistance Laminate blistering A A A A A A A A A A A A A A A A A A resistance Storage stability A A A A A A A A A A A A A A A A A A

TABLE-US-00005 TABLE 3-2 Comparative Example 11 12 13 14 15 16 17 18 19 20 Ink name T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 Printed item TT1 TT2 TT3 TT4 TT5 TT6 TT7 TT8 TT9 TT10 Melamine aqueous solution C C E C E C E C C C impregnability Dry rubbing resistance C C C B E D A C C C Wet rubbing resistance D C C A E E A C C C Laminate blistering resistance E E E D E C E E E E Storage stability A A A A E A E A A A

[0214] Based on the evaluation results, it was evident that the aqueous ink compositions of the present invention, which as a characteristic feature contained the polyacrylamide resin (A) as a water-soluble binder resin, exhibited good printability with no abrasion between the printed portion and the guide rollers (good dry rubbing resistance), good permeability following immersion (impregnation) of an adhesive during post-processing, no ink removal during that process (good wet rubbing resistance), and favorable adhesion following thermocompression bonding with a substrate during post-processing.