阅读说明：本技术 一种改性聚氨酯树脂的制备方法及可水洗油墨组合物 (Preparation method of modified polyurethane resin and washable ink composition ) 是由 赵宇晗 于 2020-12-31 设计创作，主要内容包括：本发明属于油墨技术领域,具体是一种改性聚氨酯树脂的制备方法及可水洗油墨组合物。可水洗油墨组合物按重量份数计,由以下各原料组分组成,10～20份本发明的改性聚氨酯树脂、100～150份第二有机溶剂、0～3份颜料、1～2份附着力促进剂、0～2份分散剂、0.5～1.1份防沉剂、0.4～0.8份流平剂和0.8～1.4份消泡剂；改性聚氨酯树脂采用聚乙烯醇和小分子醇对聚氨酯的两端异氰酸酯进行封端。本发明的可水洗油墨组合物自然干燥后耐轻微的酒精擦拭,但可用水冲洗干净。(The invention belongs to the technical field of ink, and particularly relates to a preparation method of modified polyurethane resin and a washable ink composition. The washable ink composition comprises, by weight, 10-20 parts of the modified polyurethane resin, 100-150 parts of a second organic solvent, 0-3 parts of a pigment, 1-2 parts of an adhesion promoter, 0-2 parts of a dispersing agent, 0.5-1.1 parts of an anti-settling agent, 0.4-0.8 part of a leveling agent and 0.8-1.4 parts of an antifoaming agent; the modified polyurethane resin adopts polyvinyl alcohol and small molecular alcohol to block isocyanate at two ends of polyurethane. The water washable ink composition disclosed by the invention is resistant to slight alcohol wiping after being naturally dried, but can be washed clean by water.)

1. A preparation method of modified polyurethane resin is characterized by comprising the following steps,

carrying out prepolymerization reaction on S1, polyethylene glycol and aliphatic or alicyclic diisocyanate at 70-100 ℃ for 2-4 hours, adding a small-molecule chain extender, and stirring for 3-8 hours to obtain a prepolymer;

s2, dropwise adding small-molecule monoalcohol into the prepolymer obtained in the step S1, stirring for 2-5 hours, adding a dibutyl tin dilaurate catalyst, stirring, and adding a first organic solvent to obtain a single-end-capped polyurethane solution;

s3, adding polyvinyl alcohol into the single-end-capped polyurethane solution obtained in the step S2, controlling the temperature to be 50-100 ℃, reacting for 3-7 hours, and removing low-boiling-point substances to obtain the modified polyurethane resin.

2. The preparation method according to claim 1, wherein the molar ratio of the polyethylene glycol, the aliphatic or alicyclic diisocyanate and the small-molecule chain extender in step S1 is (0.3-0.5): 1 (0.2-0.4).

3. The preparation method according to claim 1, wherein the small molecule chain extender in step S1 is one or more selected from 1, 2-propylene glycol, 2-methyl-1, 3-propylene glycol, neopentyl glycol and trimethylpentane glycol.

4. The preparation method according to claim 1, wherein the ratio of the number of moles of isocyanate groups to the number of moles of the small molecule mono-alcohol in the prepolymer in step S2 is 1 (0.45-0.5).

5. The method of claim 1, wherein the small molecule monoalcohol in step S2 has the structural formula ROH, wherein R is an unsubstituted C1-C6 alkyl group.

6. The method according to claim 1, wherein the first organic solvent in step S2 is one or more selected from the group consisting of N, N-dimethylformamide, N-diethylformamide, N-dimethylacetamide, dimethylsulfoxide, and cyclohexanone.

7. The method according to claim 1, wherein the molar ratio of the mole number of isocyanate groups of the single-blocked polyurethane to the mole number of the polyvinyl alcohol in the single-blocked polyurethane solution in the step S3 is 1 (0.2-1).

8. The method according to claim 1, wherein the polyvinyl alcohol in step S3 has an average relative molecular weight of 2000-2000000 and an alcoholysis degree of 50-80%.

9. A washable ink composition is characterized by comprising, by weight, 10-20 parts of the modified polyurethane resin obtained by the preparation method according to any one of claims 1-8, 100-150 parts of a second organic solvent, 0-3 parts of a pigment, 1-2 parts of an adhesion promoter, 0-2 parts of a dispersing agent, 0.5-1.1 parts of an anti-settling agent, 0.4-0.8 part of a leveling agent, and 0.8-1.4 parts of an antifoaming agent.

10. The water washable ink composition of claim 9, wherein the second organic solvent is one or more selected from tetrahydrofuran, acetone, ethyl acetate, butyl acetate, methyl ethyl ketone, cyclohexanone, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and propylene glycol dimethyl ether.

Technical Field

The invention belongs to the technical field of printing ink, and relates to a preparation method of modified polyurethane resin and a washable printing ink composition.

Background

A PCB printing ink mainly plays a role in temporary protection, and plays a role in protection in a subsequent process after being sprayed or screen-printed on a PCB and dried, after the process is finished, the PCB printing ink needs to be washed clean by normal-temperature (about 30 ℃) water, but needs to be resistant to slight alcohol wiping in process engineering, a non-woven fabric is required to be slightly wiped on the surface of the dried printing ink after being wetted by alcohol, and the printing ink does not fade on the non-woven fabric. Both the requirement of water rinse and the requirement of slight alcohol wiping put high demands on the PCB printing ink.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method of a modified polyurethane resin.

It is another object of the present invention to provide a water washable ink composition.

The technical scheme of the invention is as follows:

a preparation method of modified polyurethane resin comprises the following steps,

carrying out prepolymerization reaction on S1, polyethylene glycol and aliphatic or alicyclic diisocyanate at 70-100 ℃ for 2-4 hours, adding a small-molecule chain extender, and stirring for 3-8 hours to obtain a prepolymer;

s2, dropwise adding small-molecule monoalcohol into the prepolymer obtained in the step S1, stirring for 2-5 hours, adding a dibutyl tin dilaurate catalyst, stirring, and adding a first organic solvent to obtain a single-end-capped polyurethane solution;

s3, adding polyvinyl alcohol into the single-end-capped polyurethane solution obtained in the step S2, controlling the temperature to be 50-100 ℃, reacting for 3-7 hours, and removing low-boiling-point substances to obtain the modified polyurethane resin.

Preferably, in the step S1, the molar ratio of the polyethylene glycol, the aliphatic or alicyclic diisocyanate and the small molecular chain extender is (0.3-0.5): 1 (0.2-0.4). The aliphatic or alicyclic diisocyanate in the present invention may be selected from one or more of isophorone diisocyanate, cyclohexane dimethylene diisocyanate, methylcyclohexyl diisocyanate, hexamethylene diisocyanate and trimethylhexamethylene diisocyanate.

Preferably, the small molecule chain extender in step S1 is selected from one or more of 1, 2-propanediol, 2-methyl-1, 3-propanediol, neopentyl glycol and trimethylpentanediol.

Preferably, the ratio of the number of moles of isocyanate groups to the number of moles of small molecule monoalcohol in the prepolymer in step S2 is 1 (0.45-5). More preferably, the molar ratio is 1 (0.47 to 0.5).

Preferably, the small molecule monoalcohol in step S2 has the structural formula of ROH, wherein R is unsubstituted C1-C6 alkyl. Specifically, the small molecule monoalcohol can be selected from methanol, ethanol, isopropanol, isobutanol, n-butanol, n-hexanol or n-pentanol.

Preferably, the first organic solvent in step S2 is selected from one or more of N, N-Dimethylformamide (DMF), N-Diethylformamide (DEF), N-Dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), and cyclohexanone.

Preferably, the molar ratio of the mole number of the isocyanate groups of the single-blocked polyurethane in the single-blocked polyurethane solution to the mole number of the polyvinyl alcohol in the step S3 is 1 (0.2-1). More preferably, the molar ratio is 1 (0.3 to 0.8).

Preferably, in step S3, the polyvinyl alcohol has an average relative molecular weight of 2000 to 2000000 and an alcoholysis degree of 50 to 80%. More preferably, the polyvinyl alcohol has an average relative molecular weight of 10000 to 1000000.

The washable ink composition comprises, by weight, 10-20 parts of modified polyurethane resin obtained by the preparation method according to any one of the embodiments, 100-150 parts of a second organic solvent, 0-3 parts of a pigment, 1-2 parts of an adhesion promoter, 0-2 parts of a dispersing agent, 0.5-1.1 parts of an anti-settling agent, 0.4-0.8 part of a leveling agent and 0.8-1.4 parts of an antifoaming agent.

Preferably, the second organic solvent is one or more selected from tetrahydrofuran, acetone, ethyl acetate, butyl acetate, methyl ethyl ketone, cyclohexanone, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether and propylene glycol dimethyl ether.

In the present invention, the pigment is not particularly limited, and may be selected from red, blue, green, yellow, etc. pigments, including red iron oxide, cadmium yellow, cerium oxide, ultramarine, phthalocyanine blue, phthalocyanine green, etc.

In the present invention, the adhesion promoter is selected from silane coupling agents, more specifically, may be selected from one or more of (gamma-glycidoxypropyl) trimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N-beta-aminoethyl-gamma-aminopropyltrimethoxysilane and vinyltrimethoxysilane.

In the present invention, the dispersant is not particularly limited, and may be one or more selected from an anionic dispersant, a cationic dispersant, a nonionic dispersant, and an amphoteric dispersant. The anionic dispersant may be selected from sodium oleate, carboxylates, sulfate ester salts, sulfonates, and the like. The cationic dispersant may be selected from amine salts, quaternary ammonium salts, pyridinium salts, and the like. The nonionic dispersant is mainly polyethylene glycol polypropylene glycol polyether, polyethylene glycol alkyl ether, polyhexanolide polyol-polyethyleneimine block copolymer dispersant, acrylate high molecular dispersant or polyurethane or polyester high molecular dispersant. The amphoteric dispersant is mainly a phosphate type high molecular polymer.

In the present invention, the anti-settling agent is not particularly limited and may be selected from at least one of organic bentonite, castor oil derivatives, fumed silica, polyolefin wax, modified hydrogenated castor oil, N-methylpyrrolidone solution of modified polyurea, and polyamide wax.

In the present invention, the leveling agent is not particularly limited and may be selected from an organic silicon type leveling agent or an acrylate type leveling agent.

In the present invention, the defoaming agent is not particularly limited and may be selected from silicone defoaming agents.

The invention has the beneficial effects that:

(1) the invention designs molecular structure in modified polyurethane resin, firstly uses small molecule single alcohol to seal the isocyanate group at one end of prepolymer to obtain single seal polyurethane, then uses the hydroxyl group on polyvinyl alcohol to react with the isocyanate group at the other end of single seal polyurethane to obtain polyvinyl alcohol modified polyurethane resin, at the same time controls the mole ratio of polyvinyl alcohol and isocyanate in single seal polyurethane, only several hydroxyl groups on polyvinyl alcohol react with isocyanate, after the reaction, most of hydroxyl groups of polyvinyl alcohol are remained. Most of hydroxyl groups are reserved on the polyvinyl alcohol, so that the modified polyurethane resin has good hydrophilicity and can realize water washing of the ink, and the modified polyurethane resin reserves the incompatibility property of the polyvinyl alcohol and the ethanol, so that the obtained ink can resist a certain degree of alcohol wiping after being dried.

(2) According to the invention, the isocyanate of polyurethane is blocked by adopting the micromolecule mono-alcohol and the polyvinyl alcohol respectively, so that the isocyanate content of the obtained modified polyurethane resin is very low, the modified polyurethane resin is rarely crosslinked when the printing ink is dried, and the crosslinking degree is low, which is beneficial to realizing water washing.

(3) Polyvinyl alcohol is insoluble in most organic solvents, including absolute ethanol, at room temperature. Therefore, a polyvinyl alcohol structure is introduced into the molecular structure of the polyurethane, most of hydroxyl groups are reserved, the compatibility of the modified polyurethane resin and ethanol can be effectively reduced, and the alcohol-resistant wiping is realized to a certain extent.

Detailed Description

The technical solution of the present invention is further illustrated and described by the following detailed description.

Unless otherwise specified, the parts described in the following examples are parts by weight.

Examples 1 to 4 preparation of modified polyurethane resin

Example 1

Selecting raw materials: isophorone diisocyanate, polyethylene glycol (with a polymerization degree of 7.9), 1, 2-propylene glycol as a small-molecule chain extender, ethanol as a small-molecule monoalcohol, and polyvinyl alcohol (with an alcoholysis degree of 60%) with an average relative molecular mass of 12 million; the molar ratio of polyethylene glycol, isophorone diisocyanate and 1, 2-propylene glycol is 0.33:1: 0.22;

carrying out prepolymerization reaction on polyethylene glycol and isophorone diisocyanate at 70-75 ℃ for 4 hours, adding 1, 2-propylene glycol, and stirring for 6 hours to obtain a prepolymer; dropwise adding ethanol according to the molar ratio of the isocyanate group to the ethanol in the prepolymer of 1:0.46, stirring for 3 hours, adding a proper amount of dibutyl tin dilaurate catalyst, stirring, adding 15 times of DMF (dimethyl formamide) by weight of isophorone diisocyanate, and uniformly stirring to obtain a single-end-capped polyurethane solution; adding polyvinyl alcohol according to the molar ratio of isocyanate groups of the single-ended polyurethane to the polyvinyl alcohol of 1:0.25 in the single-ended polyurethane solution, reacting for 6 hours at 60-70 ℃, and removing low-boiling-point substances such as DMF (dimethyl formamide) to obtain the modified polyurethane resin, which is recorded as P-1.

Example 2

Selecting raw materials: cyclohexane dimethylene diisocyanate, polyethylene glycol (polymerization degree of 10.9), 1, 3-propylene glycol as a small molecular chain extender, isopropanol as a small molecular mono-alcohol, and polyvinyl alcohol (alcoholysis degree of 70%) with average relative molecular mass of 60 ten thousand; the molar ratio of polyethylene glycol, cyclohexane dimethylene diisocyanate and 1, 3-propylene glycol is 0.45:1: 0.3;

carrying out prepolymerization reaction on polyethylene glycol and cyclohexane dimethylene diisocyanate at the temperature of 80-85 ℃ for 3 hours, adding 1, 3-propylene glycol, and stirring for 5 hours to obtain a prepolymer; dropwise adding isopropanol according to the molar ratio of the isocyanate group to the isopropanol in the prepolymer of 1:0.48, stirring for 5 hours, adding a proper amount of dibutyl tin dilaurate catalyst, stirring, adding DMA (direct memory access) which is 20 times of the weight of isophorone diisocyanate, and uniformly stirring to obtain a single-end-capped polyurethane solution; adding polyvinyl alcohol according to the molar ratio of isocyanate groups of the single-ended polyurethane to the polyvinyl alcohol of 1:0.36 in the single-ended polyurethane solution, reacting for 5 hours at 70 +/-3 ℃, and removing low-boiling-point substances such as DMA (direct memory access) and the like to obtain the modified polyurethane resin, which is recorded as P-2.

Example 3

Selecting raw materials: methyl cyclohexyl diisocyanate, polyethylene glycol (the degree of polymerization is 13.5), neopentyl glycol as a small molecular chain extender, n-butyl alcohol as small molecular mono-alcohol, and polyvinyl alcohol (the degree of alcoholysis is 72%) with the average relative molecular mass of 90 ten thousand; the molar ratio of polyethylene glycol, methylcyclohexyl diisocyanate and neopentyl glycol is 0.5:1: 0.26;

carrying out prepolymerization reaction on polyethylene glycol and methyl cyclohexyl dimethylene diisocyanate at 85-90 ℃ for 3 hours, adding neopentyl glycol, and stirring for 6 hours to obtain a prepolymer; dropwise adding n-butanol according to the molar ratio of the isocyanate group to the n-butanol of 1:0.5 in the prepolymer, stirring for 3 hours, adding a proper amount of dibutyl tin dilaurate catalyst, stirring, adding 18 times of DMF (dimethyl formamide) by weight of methyl cyclohexyl diisocyanate, and uniformly stirring to obtain a single-end-capped polyurethane solution; adding polyvinyl alcohol according to the molar ratio of isocyanate groups of the single-ended polyurethane to the polyvinyl alcohol of 1:0.5 in the single-ended polyurethane solution, reacting for 4.5 hours at 80 +/-3 ℃, and removing low-boiling-point substances such as DMF (dimethyl formamide) to obtain the modified polyurethane resin, which is recorded as P-3.

Example 4

Selecting raw materials: hexamethylene diisocyanate, polyethylene glycol (the degree of polymerization is 13.5), a small-molecule chain extender is 1, 3-propylene glycol, small-molecule single alcohol is methanol, and polyvinyl alcohol with the average relative molecular mass of 100 ten thousand (the degree of alcoholysis is 75%); the molar ratio of polyethylene glycol, hexamethylene diisocyanate and 1, 3-propylene glycol is 0.42:1: 0.29;

carrying out prepolymerization reaction on polyethylene glycol and hexamethylene diisocyanate at the temperature of 90 +/-2 ℃ for 2.5 hours, adding 1, 3-propylene glycol, and stirring for 5 hours to obtain a prepolymer; dropwise adding methanol according to the molar ratio of the isocyanate group to the n-butanol of 1:0.49 in the prepolymer, stirring for 4 hours, adding a proper amount of dibutyl tin dilaurate catalyst, stirring, adding DMF (dimethyl formamide) which is 20 times of the weight of hexamethylene diisocyanate, and uniformly stirring to obtain a single-end-capped polyurethane solution; adding polyvinyl alcohol according to the molar ratio of isocyanate groups of the single-ended polyurethane to the polyvinyl alcohol of 1:0.75 in the single-ended polyurethane solution, reacting for 3.5 hours at 90 +/-3 ℃, and removing low-boiling-point substances such as DMF (dimethyl formamide) to obtain the modified polyurethane resin, which is recorded as P-4.

Example 5

In example 4, polyvinyl alcohol was added in a molar ratio of isocyanate groups of the single-blocked polyurethane to polyvinyl alcohol of 1:0.93 in the single-blocked polyurethane solution, and the remaining steps were kept unchanged to obtain a modified polyurethane resin, which was designated as P-5.

Examples 6-13 preparation of Water washable ink compositions

Example 6

According to the raw materials: 10 parts of modified polyurethane resin 1 in example 1, 100 parts of tetrahydrofuran, 1.2 parts of (gamma-glycidoxypropyl) trimethoxysilane, 0.7 part of fumed silica, 0.6 part of an organosilicon leveling agent and 0.8 part of an organosilicon defoaming agent,

adding the modified polyurethane resin 1 into tetrahydrofuran, stirring for dissolving, adding an organic silicon leveling agent, stirring for dispersing uniformly, adding an organic silicon defoaming agent, stirring for dispersing uniformly, adding fumed silica, stirring for dispersing uniformly, adding (gamma-glycidoxypropyl) trimethoxysilane, stirring uniformly, and filtering to obtain an ink composition, which is marked as Y-1.

Example 7

According to the raw materials: 16 parts of modified polyurethane resin 2 in example 2, 100 parts of butyl acetate, 20 parts of acetone, 2 parts of cadmium yellow, 1.5 parts of gamma-methacryloxypropyl trimethoxysilane, 0.7 part of polyacrylate type hyper-dispersant, 0.9 part of organic bentonite, 0.6 part of organic silicon leveling agent and 1 part of organic silicon defoaming agent,

adding the modified polyurethane resin 2 into butyl acetate and acetone, stirring for dissolving, adding cadmium yellow and a polyacrylate super-dispersant, stirring and dispersing uniformly, adding an organic silicon leveling agent, stirring and dispersing uniformly, adding an organic silicon defoaming agent, stirring and dispersing uniformly, adding organic bentonite, stirring and dispersing uniformly, adding gamma-methacryloxypropyl trimethoxysilane, stirring uniformly, and filtering to obtain the ink composition marked as Y-2.

Example 8

According to the raw materials: 20 parts of the modified polyurethane resin 3 of example 3, 100 parts of butyl acetate, 30 parts of ethylene glycol dimethyl ether, 20 parts of acetone, 2 parts of iron oxide red, 2 parts of gamma-aminopropyltriethoxysilane, 0.8 part of polyacrylate super dispersant, 1 part of organobentonite, 0.8 part of acrylate leveling agent and 0.9 part of silicone defoamer dispersed with fumed silica,

adding the modified polyurethane resin 3 into butyl acetate, ethylene glycol dimethyl ether and acetone, stirring for dissolving, adding iron oxide red and a polyacrylate super dispersant, stirring and dispersing uniformly, adding an acrylate leveling agent, stirring and dispersing uniformly, adding an organic silicon defoamer dispersed with fumed silica, stirring and dispersing uniformly, adding organic bentonite, stirring and dispersing uniformly, adding gamma-aminopropyltriethoxysilane, stirring uniformly, filtering, and obtaining the ink composition marked as Y-3.

Example 9

According to the raw materials: 13 parts of the modified polyurethane resin 4 of example 4, 120 parts of ethylene glycol dimethyl ether, 2 parts of phthalocyanine blue, 1.2 parts of N-beta-aminoethyl-gamma-aminopropyltrimethoxysilane, 1 part of polyhexamethylene polyol-polyethyleneimine block copolymer type dispersant, 0.8 part of fumed silica, 0.5 part of an organosilicon leveling agent and 1 part of an organosilicon defoaming agent,

adding the modified polyurethane resin 4 into ethylene glycol dimethyl ether, stirring and dissolving, adding phthalocyanine blue and polyhexamethylene internal polyester polyol-polyethyleneimine segmented copolymer type dispersing agent, stirring and dispersing uniformly, adding an organic silicon leveling agent, stirring and dispersing uniformly, adding an organic silicon defoaming agent, stirring and dispersing uniformly, adding fumed silica, stirring and dispersing uniformly, adding N-beta-aminoethyl-gamma-aminopropyltrimethoxysilane, stirring uniformly, and filtering to obtain an ink composition which is marked as Y-4.

Example 10

According to the raw materials: 17 parts of modified polyurethane resin 5 in example 5, 135 parts of butyl acetate, 1.5 parts of vinyltrimethoxysilane, 1 part of organobentonite, 0.6 part of an organosilicon leveling agent and 1 part of an antifoaming agent,

adding the modified polyurethane resin 5 into butyl acetate, stirring for dissolving, adding the organic silicon leveling agent, stirring for dispersing uniformly, adding the organic silicon defoaming agent, stirring for dispersing uniformly, adding the organic bentonite, stirring for dispersing uniformly, adding the vinyl trimethoxy silane, stirring uniformly, and filtering to obtain the ink composition, which is marked as Y-5.

Example 11

According to the raw materials: 15 parts of modified polyurethane resin 2 in example 2, 100 parts of ethylene glycol monomethyl ether, 30 parts of butyl acetate, 1.5 parts of gamma-methacryloxypropyltrimethoxysilane, 1 part of modified hydrogenated castor oil, 0.8 part of polyacrylate type leveling agent and 1 part of silicone defoamer,

adding the modified polyurethane resin 2 into ethylene glycol monomethyl ether and butyl acetate, stirring for dissolving, adding a polyacrylate type leveling agent, stirring for dispersing uniformly, adding an organic silicon defoaming agent, stirring for dispersing uniformly, adding modified hydrogenated castor oil, stirring for dispersing uniformly, adding gamma-methacryloxypropyl trimethoxysilane, stirring uniformly, filtering, and obtaining the ink composition which is marked as Y-6.

Example 12

According to the raw materials: 18 parts of the modified polyurethane resin 3 of example 3, 100 parts of butyl acetate, 40 parts of ethylene glycol dimethyl ether, 1.8 parts of gamma-aminopropyltriethoxysilane, 0.9 part of organobentonite, 0.6 part of an organosilicon leveling agent and 1 part of an organosilicon defoaming agent,

adding the modified polyurethane resin 3 into ethylene glycol monomethyl ether and butyl acetate, stirring for dissolving, adding an organic silicon flatting agent, stirring for dispersing uniformly, adding an organic silicon defoaming agent, stirring for dispersing uniformly, adding organic bentonite, stirring for dispersing uniformly, adding gamma-aminopropyltriethoxysilane, stirring uniformly, and filtering to obtain an ink composition, which is marked as Y-7.

Example 13

According to the raw materials: 20 parts of the modified polyurethane resin 4 of example 4, 150 parts of ethylene glycol dimethyl ether, 1 part of ultramarine, 1.3 parts of methyltriethoxysilane, 1 part of polyacrylate dispersant, 0.8 part of fumed silica, 0.6 part of polyacrylate leveling agent and 0.9 part of defoaming agent,

adding the modified polyurethane resin 4 into ethylene glycol monomethyl ether, stirring for dissolving, adding ultramarine and polyacrylate type hyper-dispersant, adding polyacrylate type leveling agent, stirring for dispersing uniformly, adding an organic silicon defoamer, stirring for dispersing uniformly, adding fumed silica, stirring and dispersing uniformly, adding methyltriethoxysilane, stirring uniformly, filtering, and obtaining the ink composition marked as Y-8.

Comparative example 1

In example 3, polyvinyl alcohol was added in a molar ratio of isocyanate groups of the one-blocked polyurethane to polyvinyl alcohol of 1:0.1 in the one-blocked polyurethane solution, and the remaining steps were kept unchanged to obtain a modified polyurethane resin, which was designated as P-6.

In example 7, the modified polyurethane resin P-2 was replaced with the modified polyurethane resin P-6, and the other steps were kept unchanged to obtain an ink composition, which was designated as Y-9.

Comparative example 2

In example 3, the step of adding n-butanol was omitted, and polyvinyl alcohol was added in a molar ratio of isocyanate groups to polyvinyl alcohol of 1:0.5 in the prepolymer, and the remaining steps were kept unchanged, and it was found that the viscosity of the reaction system gradually increased with the increase of the reaction time, and a non-flowable gel was formed within 20 minutes.

Comparative example 3

In example 3, no n-butanol and polyvinyl alcohol were added, and the remaining steps were kept unchanged to obtain a polyurethane resin, designated P-7.

In example 7, the polyurethane resin P-7 was used in place of the modified polyurethane resin P-2, and the other steps were kept unchanged to obtain an ink composition, which was designated as Y-10.

Comparative example 4

In example 3, polyvinyl alcohol was added in a molar ratio of isocyanate groups of the one-blocked polyurethane to polyvinyl alcohol of 1:1.2 in the one-blocked polyurethane solution, and the remaining steps were kept unchanged to obtain a modified polyurethane resin, which was designated as P-8.

In example 7, the polyurethane resin P-8 was used in place of the modified polyurethane resin P-2, and the other steps were kept unchanged to obtain an ink composition, which was designated as Y-11.

Comparative example 5

In example 3, n-butanol was added dropwise in a molar ratio of isocyanate groups to n-butanol of 1:1 in the prepolymer, the step of adding polyvinyl alcohol was omitted, and the remaining steps were kept the same to obtain a modified polyurethane resin, which was designated as P-9.

In example 7, the polyurethane resin P-9 was used in place of the modified polyurethane resin P-2, and the other steps were kept unchanged to obtain an ink composition, which was designated as Y-12.

Results testing

And spraying the ink compositions Y-1 to Y-12 to be tested on the PCB, and drying for 24 hours at room temperature to obtain a sample to be tested.

And (3) water washing test: spraying the sample to be detected with deionized water at 30 +/-1 ℃ for 5 minutes under the spraying pressure of 1.5-2.5 Kg/cm²And blowing the mixture to dry by adopting nitrogen after spraying, and observing whether the mixture is cleaned. As shown in Table 1, the results are "O" indicates clean and no residue, "X" indicates no clean and slight residue, and "XX" indicates no clean and serious residue.

Alcohol rub resistance test: and slightly wiping the sample to be detected with the non-woven fabric wetted by the alcohol, wiping the sample back and forth for 10 times, and observing whether the ink migrates to the non-woven fabric. The results are shown in Table 1, "O" indicates no migration of the ink, "X" indicates slight migration of the ink, and "XX" indicates severe migration of the ink.

TABLE 1

	Washing with water	Alcohol-resistant wiping
			Ink composition Y-2	O	O
Ink composition Y-3	O	O
			Ink composition Y-4	O	O
Ink composition Y-5	O	O
			Ink composition Y-6	O	O
Ink composition Y-8	O	O
			Ink composition Y-9	X	XX
Ink composition Y-10	X	XX
			Ink composition Y-11	X	O
Ink composition Y-12	XX	XX

As can be seen from the results in Table 1, the water-washable ink composition prepared from the modified polyurethane resin of the present invention has good washing property after natural drying and can resist slight wiping with alcohol.

The foregoing has shown and described the fundamental principles, principal features and advantages of the invention. It should be understood by those skilled in the art that the present invention is not limited by the foregoing embodiments, which are merely preferred embodiments of the present invention, and the scope of the present invention should not be limited thereby, and that equivalent changes and modifications made within the scope of the present invention and the specification should be covered thereby. The scope of the invention is defined by the appended claims and equivalents thereof.