阅读说明：本技术 纸制品用可再分散丙烯酸酯热熔胶及其制备方法 (Redispersible acrylate hot melt adhesive for paper products and preparation method thereof ) 是由 郭敏杰 刘兴之 郭维礼 于 2020-07-23 设计创作，主要内容包括：本发明公开了一种纸制品用可再分散丙烯酸酯热熔胶及其制备方法,该热熔胶通过将79～93重量份的石蜡改性的丙烯酸酯聚合物、1～15重量份的邻苯二甲酸二辛酯和1～12重量份的松香熔融混合均匀制成；其中,所述石蜡改性的丙烯酸酯聚合物由甲基丙烯酸甲酯、甲基丙烯酸甲酯、甲基丙烯酸月桂酯、乙酸乙烯酯和丙烯酸在石蜡乳液中共聚而成；该热熔胶可在废纸回收过程中,以微小颗粒形式再分散于水中,便于清除,不损害机器和再生纸质量；其使用时的熔融温度在73～86℃之间,热分解温度在367～377℃之间,符合低温热熔胶的要求,操作温度范围宽,且几乎不产生甲醛气体,不发生热熔胶剥皮、积碳以及氧化分解等老化现象。(The invention discloses a redispersible acrylate hot melt adhesive for paper products and a preparation method thereof, wherein the hot melt adhesive is prepared by melting and uniformly mixing 79-93 parts by weight of paraffin-modified acrylate polymer, 1-15 parts by weight of dioctyl phthalate and 1-12 parts by weight of rosin; wherein the paraffin-modified acrylate polymer is formed by copolymerizing methyl methacrylate, lauryl methacrylate, vinyl acetate and acrylic acid in a paraffin emulsion; the hot melt adhesive can be redispersed in water in the form of tiny particles in the process of waste paper recovery, is convenient to remove, and does not damage the quality of machines and recycled paper; the melting temperature is 73-86 ℃ and the thermal decomposition temperature is 367-377 ℃ during use, the requirement of low-temperature hot melt adhesive is met, the operating temperature range is wide, formaldehyde gas is hardly generated, and the phenomena of peeling, carbon deposition, oxidative decomposition and other aging of the hot melt adhesive are avoided.)

1. A redispersible acrylate hot melt adhesive for paper products is characterized by comprising 79-93 parts by weight of paraffin-modified acrylate polymer, 1-15 parts by weight of dioctyl phthalate and 1-12 parts by weight of rosin; wherein the paraffin-modified acrylate polymer is formed by copolymerizing methyl methacrylate, lauryl methacrylate, vinyl acetate and acrylic acid in a paraffin emulsion.

2. The redispersible acrylate hot melt adhesive for paper products according to claim 1, wherein the paraffin-modified acrylate polymer is prepared from the following raw materials in the following amounts: 18-29 parts of methyl methacrylate, 1-12 parts of lauryl methacrylate, 3-7 parts of vinyl acetate, 3-7 parts of acrylic acid, 2-10 parts of paraffin emulsion and 50-58 parts of deionized water, and a persulfate initiator accounting for 0.1-0.4% of the total weight of the copolymer monomer, the paraffin emulsion and the deionized water, 0.4-1.8% of an emulsifier B, 0.1-0.3% of a buffering agent, 0.1-0.8% of a chain transfer agent and 0.1-1.2% of a cross-linking agent; wherein the paraffin emulsion is formed by mixing 15-25 parts of sliced paraffin, 5-15 parts of composite emulsifier A and 70-80 parts of deionized water; the emulsifier A is a composite emulsifier composed of alkylphenol polyoxyethylene ether-10 and span 80 in a weight ratio of 8-12: 9; the emulsifier B is a composite emulsifier formed by mixing 3-4: 1 by weight of alkylphenol polyoxyethylene ether-10 and sodium dodecyl sulfate.

3. The redispersible acrylate hot melt adhesive for paper products according to claim 2, characterized in that the buffering agent is sodium bicarbonate.

4. A redispersible acrylate hot melt adhesive for paper products as claimed in claim 2, characterized in that said persulfate initiator is potassium persulfate.

5. The redispersible acrylate hot melt adhesive for paper products according to claim 2, wherein the chain transfer agent is n-dodecyl mercaptan or t-dodecyl mercaptan.

6. A redispersible acrylate hot melt adhesive for paper products according to claim 2, characterized in that said crosslinking agent is N- (butoxymethyl) acrylamide.

7. A method for preparing the redispersible acrylate hot melt adhesive for paper products as claimed in claim 1, characterized by comprising the following steps:

preparing a paraffin modified acrylate polymer:

s1, placing the sliced paraffin and the composite emulsifier A in a reaction container, setting the temperature at 75 ℃, starting stirring after the paraffin is completely melted, dropwise adding isothermal deionized water within 20 minutes after stirring uniformly, continuing stirring for 40min under heat preservation, and cooling to obtain a paraffin emulsion; wherein the emulsifier A is a composite emulsifier of alkylphenol polyoxyethylene ether-10 and span 80 in a weight ratio of 8-12: 9;

s2, mixing and stirring part of deionized water, the composite emulsifier B and sodium bicarbonate for 10-15 minutes to obtain a mixed solution; wherein the emulsifier B is a composite emulsifier formed by mixing 3-4: 1 by weight of alkylphenol polyoxyethylene ether-10 and sodium dodecyl sulfate;

s3, uniformly mixing methyl methacrylate, lauryl methacrylate, vinyl acetate, acrylic acid and a chain transfer agent to obtain a monomer mixed solution;

s4, dissolving potassium persulfate in part of deionized water to prepare a potassium persulfate aqueous solution;

s5, setting the temperature of the mixed solution to be 40 ℃, adding 1/4 parts by weight of monomer mixed solution and 1/5 parts by weight of potassium persulfate aqueous solution into the mixed solution, uniformly stirring, continuously heating to 60 ℃, adding paraffin emulsion into the mixed solution, mixing and stirring for 10-15 minutes, continuously heating to 75-78 ℃, after dropwise adding the residual monomer mixed solution, the potassium persulfate aqueous solution and the cross-linking agent within 1.5-2 hours, continuously stirring and reacting at 75-78 ℃ for 1.5 hours, and then cooling the obtained composite emulsion to room temperature; dropwise adding a saturated sodium chloride solution into the composite emulsion, and violently stirring at the speed of 200-250 r/min until obvious polymer precipitation occurs in the system, stopping dropwise adding, washing the polymer precipitation for 2-10 times by using deionized water, and drying at 50 ℃ to obtain an acrylate polymer for the hot melt adhesive;

(II) preparing a paraffin-modified acrylate polymer:

preparing a hot melt adhesive: and uniformly mixing the paraffin-modified acrylate polymer, dioctyl phthalate and rosin in a molten state to obtain the redispersible acrylate hot melt adhesive for paper products.

Technical Field

The invention relates to the technical field of hot melt adhesives, and particularly relates to a redispersible acrylate hot melt adhesive for paper products and a preparation method thereof.

Background

At present, the consumption of paper products in China per year is reported to reach 3500 ten thousand tons, rich waste paper resources build the waste paper market in China, and the reasonable recycling of waste paper becomes a difficult problem in the environmental protection process in China. In the process of recycling paper products, various original impurities are removed to ensure the smooth proceeding of waste paper repulping. The removal of adhesive substances is mainly solved in the waste paper recovery process, the adhesive substances in the waste paper mainly comprise various pressure-sensitive adhesives, hot melt adhesives, wax substances, coating adhesives and the like, and the substances can remain in a forming net, a pressing felt, a pressing roller and a drying cylinder in the waste paper recovery process to influence the normal operation of the machine; on the other hand, the produced paper product has poor quality and cannot meet the daily use requirement.

The 2016 industry data published by the European paper industry Association indicates that the highest recovery of waste paper in Europe in 2015 is as high as 71.5%, and the 2020 is planned to increase the recovery of waste paper to 74%. The recovery rate of waste paper is estimated to reach 50% in 2020 of China, but is far less than that of other countries. On the basis of solving the problem of adhesive substances in waste paper recycling, water-soluble and redispersable adhesives are researched most, and the European and American countries stipulate the standard of a 'repulpable' pressure-sensitive adhesive which is divided into water-soluble and 'redispersable' pressure-sensitive adhesives and can be dissolved in water or dispersed in water in the form of tiny particles in the waste paper recycling process, so that the aim of removing the adhesives in paper product recycling is fulfilled; secondly, the product with high hydrophobicity and enough cohesive strength is produced, is not easy to disintegrate during pulping, can be filtered, screened and removed, but may cause damage to production due to incomplete treatment; and thirdly, the adhesive and the waste paper have larger density difference, so that the adhesive and the waste paper are removed by centrifugation, and the running cost is higher.

The adhesives mainly used for bonding paper products at present comprise starch glue, EVA (ethylene vinyl acetate), white latex (polyacrylates and polyvinyl alcohols) and the like, the cohesive strength of the starch adhesive is low, the starch adhesive is not suitable for packaging boxes which need to bear loads, and other types of colloids are difficult to remove in the waste paper recycling process, have high viscosity, are easy to deposit and remain in machines, damage the machines and possibly cause the quality problem of recycled paper products. Therefore, in order to avoid the problem of sticky substances from the source, an adhesive which has moderate bonding strength and cohesive strength and is easy to remove is urgently needed to be designed.

Disclosure of Invention

The invention aims to provide a redispersible acrylic acid ester hot melt adhesive for paper products, which has excellent bonding performance and can redisperse tiny particles in water for convenient removal in the process of recycling waste paper.

The invention also aims to provide a preparation method of the redispersible acrylic acid ester hot melt adhesive for paper products.

Therefore, the technical scheme of the invention is as follows:

a redispersible acrylate hot melt adhesive for paper products comprises 79-93 parts by weight of paraffin-modified acrylate polymer, 1-15 parts by weight of dioctyl phthalate and 1-12 parts by weight of rosin; wherein the paraffin-modified acrylate polymer is formed by copolymerizing methyl methacrylate, lauryl methacrylate, vinyl acetate and acrylic acid in a paraffin emulsion.

Preferably, the paraffin-modified acrylate polymer is prepared from the following raw materials in the following amount: 18-29 parts of methyl methacrylate, 1-12 parts of lauryl methacrylate, 3-7 parts of vinyl acetate, 3-7 parts of acrylic acid, 2-10 parts of paraffin emulsion and 50-58 parts of deionized water, and a persulfate initiator accounting for 0.1-0.4% of the total weight of the copolymer monomer, the paraffin emulsion and the deionized water, 0.4-1.8% of an emulsifier B, 0.1-0.3% of a buffering agent, 0.1-0.8% of a chain transfer agent and 0.1-1.2% of a cross-linking agent; wherein the paraffin emulsion is formed by mixing 15-25 parts of sliced paraffin, 5-15 parts of composite emulsifier A and 70-80 parts of deionized water; the emulsifier A is a composite emulsifier composed of alkylphenol polyoxyethylene ether-10 and span 80 in a weight ratio of 8-12: 9; the emulsifier B is a composite emulsifier formed by mixing 3-4: 1 by weight of alkylphenol polyoxyethylene ether-10 and sodium dodecyl sulfate.

Preferably, the buffer is sodium bicarbonate.

Preferably, the persulfate initiator is potassium persulfate.

Preferably, the chain transfer agent is n-dodecyl mercaptan or t-dodecyl mercaptan.

Preferably, the crosslinking agent is N- (butoxymethyl) acrylamide.

A preparation method of the redispersible acrylate hot melt adhesive for the paper products comprises the following steps:

preparing a paraffin modified acrylate polymer:

s1, placing the sliced paraffin and the composite emulsifier A in a reaction container, setting the temperature at 75 ℃, starting stirring after the paraffin is completely melted, dropwise adding isothermal deionized water within 20 minutes after stirring uniformly, continuing stirring for 40min under heat preservation, and cooling to obtain a paraffin emulsion; wherein the emulsifier A is a composite emulsifier of alkylphenol polyoxyethylene ether-10 and span 80 in a weight ratio of 8-12: 9;

s2, mixing and stirring part of deionized water, the composite emulsifier B and sodium bicarbonate for 10-15 minutes to obtain a mixed solution; wherein the emulsifier B is a composite emulsifier formed by mixing 3-4: 1 by weight of alkylphenol polyoxyethylene ether-10 and sodium dodecyl sulfate;

s3, uniformly mixing methyl methacrylate, lauryl methacrylate, vinyl acetate, acrylic acid and a chain transfer agent to obtain a monomer mixed solution;

s4, dissolving potassium persulfate in part of deionized water to prepare a potassium persulfate aqueous solution;

s5, setting the temperature of the mixed solution to be 40 ℃, adding 1/4 parts by weight of monomer mixed solution and 1/5 parts by weight of potassium persulfate aqueous solution into the mixed solution, uniformly stirring, continuously heating to 60 ℃, adding paraffin emulsion into the mixed solution, mixing and stirring for 10-15 minutes, continuously heating to 75-78 ℃, after dropwise adding the residual monomer mixed solution, the potassium persulfate aqueous solution and the cross-linking agent within 1.5-2 hours, continuously stirring and reacting at 75-78 ℃ for 1.5 hours, and then cooling the obtained composite emulsion to room temperature; dropwise adding a saturated sodium chloride solution into the composite emulsion, and violently stirring at the speed of 200-250 r/min until obvious polymer precipitation occurs in the system, stopping dropwise adding, washing the polymer precipitation for 2-10 times by using deionized water, and drying at 50 ℃ to obtain an acrylate polymer for the hot melt adhesive;

(II) preparing a paraffin-modified acrylate polymer:

preparing a hot melt adhesive: and uniformly mixing the paraffin-modified acrylate polymer, dioctyl phthalate and rosin in a molten state to obtain the redispersible acrylate hot melt adhesive for paper products.

Compared with the prior art, the redispersible acrylate hot melt adhesive for the paper product has the following beneficial effects:

(1) the dispersible hot melt adhesive can be redispersed in water in the form of tiny particles within 15-25 s in a dispersion effect test. The adhesive is applied to bonding paper products, and can avoid the problems of machine blockage, poor quality of recycled paper and the like in the waste paper recycling process, improve the waste paper recycling efficiency and reduce the energy loss in the recycling process;

(2) the dispersible hot melt adhesive has the melting temperature of 73-86 ℃, the thermal decomposition temperature of 367-377 ℃, belongs to a low-temperature hot melt adhesive, has low gluing temperature, and saves energy consumption during use; the cross-linking agent with high thermal stability is used, free formaldehyde is not generated at normal working temperature, the colloid is not easy to oxidize and decompose, and the problems of blocking a hot melt adhesive machine and the like are avoided;

(3) the T-shaped peel strength of the redispersible hot melt adhesive is 49-58N/25 mm under the test of the standard GB/T2791-1995, the higher T-shaped peel strength meets the bonding strength required by bonding paper products, and the bonding strength of the hot melt adhesive is further improved by adding rosin; the single lap shear strength of the redispersible hot melt adhesive can reach 3-4.5 Mpa under the standard GB/T33334-2016, high cohesive strength is shown, namely, the redispersible hot melt adhesive is not easy to damage, and the extrusion resistance strength of a paper package is increased; the redispersible hot melt adhesive has low melt viscosity of 15-20 Pa.s, has good fluidity by adding dioctyl phthalate, is convenient for gluing, and improves the production efficiency.

Detailed Description

The present invention will be further described with reference to the following examples, which are not intended to limit the invention in any way.