KR101535567B1 - Adhesive for manufacturing synthetic leather and manufacturing method of synthetic leather - Google Patents

Abstract

The present invention provides an adhesive for the production of synthetic leather in the form of a composition comprising a starch-based polymer particle water-based emulsion, an adhesive reinforcing agent and a viscosity controlling agent. The adhesive for synthetic leather production according to the present invention is eco-friendly and has excellent adhesive force because it contains a large amount of starch. Synthetic leather produced by using the adhesive according to the present invention has excellent adhesive strength, does not cause yellowing, and has softness similar to that of natural leather. Therefore, natural leather can be substituted for materials such as bags and belts.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an adhesive for manufacturing synthetic leather and a method for manufacturing synthetic leather using the same,

The present invention relates to an adhesive for the production of synthetic leather and a method for producing synthetic leather, and more particularly, to an adhesive used for laminating a fiber layer and a surface layer in the production of synthetic leather comprising a fiber layer and a surface layer laminated thereon, To a method of making synthetic leather.

Synthetic leather is generally composed of a surface layer made of a synthetic resin foam and a fiber layer of a fabric material. Since the synthetic leather has an appearance and function close to natural leather, materials such as bags and belts are gradually being replaced by natural leather to synthetic leather.

A typical method for producing synthetic leather includes the steps of coating a foamed polyurethane resin or a foamable polyvinyl chloride resin on the surface of a release paper to a predetermined thickness and foaming to form a surface layer (or a skin layer) comprising a foam of a synthetic resin; Forming an adhesive layer by applying an adhesive to the surface layer; And placing the fabric on the adhesive layer, pressing or heating the same, and drying the fabric, thereby laminating the fabric with the surface layer. At this time, the adhesive mainly used for laminating the fabric with the surface layer is in the form of a composition containing polyvinyl chloride resin and plasticizer as a main component. Synthetic leather produced by using such an adhesive has a problem that softness is lower than that of natural leather. Further, the polyvinyl chloride resin, which is a main component of the adhesive, is a petroleum-based material and lacks environmentally friendly characteristics such as a large amount of volatile organic compound (VOC) generated during the manufacturing process or use of the adhesive, There is a problem that the manufacturing cost may be increased due to external factors such as anxiety of supply and demand of the material and exhaustion of the petroleum-based material. Phthalate plasticizers are mainly used as plasticizers for polyvinyl chloride resins. Phthalate plasticizers have been managed as environmental hormone-estimating substances causing endocrine disruption in various countries around the world. In particular, diethylhexyl phthalate (DEHP), dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP) were found to be carcinogenic, mutagenic and regenerative toxicants. In addition, the use of diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), dynomal octyl phthalate (DNOP or DOP) is prohibited for toys and children's products that may enter the mouth. Furthermore, phthalate plasticizers may release many harmful substances such as poisonous gas when a fire occurs.

Therefore, it is necessary to replace the main component of the adhesive used for laminating the fabric to the surface layer in the process of producing synthetic leather with an environmentally friendly material.

SUMMARY OF THE INVENTION The present invention has been made under the background of the prior art, and one object of the present invention is to provide a method for forming a fiber layer such as a woven fabric, a nonwoven fabric or a knitted fabric in the process of producing a synthetic leather to be used for laminating a surface layer such as a polyvinyl chloride foam or a polyurethane foam, And an adhesive exhibiting excellent adhesive strength and the like.

Another object of the present invention is to provide a method for producing a synthetic leather using an environmentally friendly adhesive.

In order to solve one object of the present invention, the present invention relates to a composition comprising a starch-based polymer particle water-based emulsion, an adhesion enhancer and a viscosity controlling agent, wherein the starch-based polymer particle comprises a starch decomposition product and a core comprising a hard monomer and a soft monomer A core made of a starch-based copolymer formed by polymerization of a monomer mixture; And a shell formed of a copolymer formed on the core by polymerization of a shell monomer mixture comprising a hard monomer and a soft monomer, wherein the hard monomer has an ethylenically unsaturated bond, Wherein the homopolymer is a monomer having a glass transition temperature of 30 占 폚 to 250 占 폚 and the soft monomer has an ethylenically unsaturated bond and the homopolymer has a glass transition temperature of 10 占 폚 to -80 占 폚 Thereby providing an adhesive.

According to another aspect of the present invention, there is provided a method for producing a foamed synthetic resin composition, comprising the steps of: applying a foamable synthetic resin composition to a release paper and foaming to form a surface layer comprising a synthetic resin foam; Applying the synthetic leather-forming adhesive according to any one of claims 1 to 12 to the upper surface of the surface layer; And a step of placing the fiber fabric on the applied synthetic leather-forming adhesive, heating and drying the fiber fabric, and laminating the fiber fabric on the surface layer.

The adhesive for synthetic leather production according to the present invention is eco-friendly and has excellent adhesive force because it contains a large amount of starch. Synthetic leather produced by using the adhesive according to the present invention has excellent adhesive strength, does not cause yellowing, and has softness similar to that of natural leather. Therefore, natural leather can be substituted for materials such as bags and belts.

Hereinafter, the present invention will be described in detail.

One aspect of the present invention relates to an adhesive used for laminating a fiber layer and a surface layer in the production of a synthetic leather comprising a fiber layer and a surface layer laminated thereon. The synthetic leather-forming adhesive according to the present invention has the form of a composition comprising a starch-based polymer particle water-based emulsion, an adhesive reinforcing agent and a viscosity controlling agent. Hereinafter, the adhesive for synthetic leather production according to the present invention will be described by dividing it into constituent components.

Starch-based  Polymer particle water system emulsion

In the present invention, the starch-based polymer particle water-based emulsion is an emulsion containing starch-based polymer particles as a dispersion medium and containing water as a dispersion medium. At this time, the starch-based polymer particles include a core and a shell formed on the core.

In the present invention, the core comprises a starch-based copolymer formed by the polymerization of a mixture of starch hydrolysates and core monomers. In the present invention, the starch hydrolyzate used for forming the starch-based copolymer constituting the core is obtained by treating starch with enzymes, acids, heat or the like, and decomposing the hydrolyzable starch into water. The starch hydrolyzate preferably has a dextrose equivalent (DE) value of 1 to 50, more preferably 5 to 40. However, when the starch hydrolyzate can be liquefied in water, the starch hydrolyzate is not limited in its kind, . The raw starch for obtaining the starch hydrolyzate includes all natural starches derived from plants, physically or chemically modified starches, and the like. The natural starches may be selected from various plant-derived starches (i.e., unmodified starches) including corn, waxy corn, potatoes, sweet potatoes, wheat, rice, tapioca, sago, waxy maize, sorghum, . In addition, the modified starch includes all the starches obtained by reforming the unmodified starch by methods such as etherification, esterification, oxidation, acid treatment, oxidative esterification, oxidative etherification, enzyme treatment and the like. In the present invention, the starch hydrolyzate used for forming the starch-based copolymer constituting the core preferably has at least one functional group selected from the group consisting of a carboxyl group, a carbonyl group, an aldehyde group and an ester group from the viewpoint of improving the efficiency of the polymerization reaction Preferably, the starch hydrolyzate is produced by decomposing at least one modified starch selected from the group consisting of oxidized starch, esterified starch and oxidized esterified starch, or may be prepared by oxidizing, esterifying or dissolving a starch hydrolyzate obtained by decomposing unmodified starch And then oxidatively esterified. The core monomer mixture used to form the starch copolymer constituting the core in the present invention comprises a hard monomer and a soft monomer. The term "hard monomer" refers to a monomer containing an ethylenically unsaturated bond such as a vinyl group, an allyl group or an acryl group, and the homopolymer is not tacky at room temperature. In the present invention, the light-weight monomer has such a characteristic, and at the same time, the homopolymer is a monomer having a glass transition temperature of 30 ° C to 250 ° C, preferably 40 ° C to 200 ° C. In the present invention, the type of the hard monomer is not particularly limited as long as it satisfies the above-mentioned characteristics, and preferably styrene, methyl methacrylate, ethyl methacrylate, butyl methacrylate, acrylonitrile, methacrylonitrile, And may be composed of at least one member selected from the group consisting of vinyl acetate, vinyl acetate, vinyl acetate, vinyl acetate, vinyl acetate, vinyl acetate, vinyl acetate, and vinyl chloride. Also, the soft monomer refers to a monomer containing an ethylenic unsaturated bond such as a vinyl group, an allyl group or an acryl group, and the homopolymer is tacky at room temperature. In the present invention, the soft monomer has such a characteristic, and at the same time, the homopolymer is a monomer having a glass transition temperature of from 10 캜 to -80 캜, preferably from 5 캜 to -60 캜. In the present invention, the type of the soft monomer is not particularly limited as long as it satisfies the above-mentioned characteristics, and preferable examples thereof include methyl acrylate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate, ethylhexyl methacrylate, Hydroxyethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate. In addition, the core monomer mixture preferably further comprises a carboxylic acid monomer. In the present invention, the carboxylic acid monomer serves to increase the adhesive strength of the starch-based polymer particles having a core-shell structure, and the type of the carboxylic acid having an ethylenically unsaturated bond is not particularly limited, At least one member selected from the group consisting of acetic acid, maleic acid, maleic acid, maleic acid, maleic acid, maleic acid, maleic acid, maleic acid, maleic acid, maleic acid, In addition, the core monomer mixture may preferably further comprise a chain transfer agent. In the present invention, the chain transfer agent is used for controlling the molecular weight of the copolymer and is not limited in its kind, and preferably n-dodecyl mercaptan, t-dodecyl mercaptan, 1,5- Hexanedithiol, 2-ethylhexyl-3-mercaptopropionate, butyl 3-mercaptopropionate, dodecyl 3-mercaptopropionate, ethyl 2-mercaptopropionate Methyl 3-mercaptopropionate, pentaerythritol tetrakis (3-mercaptopropionate), 2-ethylhexyl mercaptoacetate, ethyl 2-mercaptoacetate , 2-hydroxymethyl-2-methyl-1,3-propanediol, and pentaerythritol tetrakis (2-mercaptoacetate). The weight ratio of the starch hydrolyzate and core monomer mixture used to form the starch copolymer constituting the core of the present invention, the weight ratio of the hard monomer, soft monomer, carboxylic acid monomer or chain precursor constituting the core monomer mixture, - glass transition temperature of the shell-type starch-based polymer particles is in the range of 5 to 25 占 폚. For example, the weight ratio of the starch degradate to the core monomer mixture in the core is preferably from 1: 0.5 to 1: 5, more preferably from 1: 1 to 1: 4 in terms of ensuring environmental friendliness and economic reliability as the amount of starch degradation increases. , And most preferably from 1: 1.5 to 1: 3.5. In addition, the weight ratio of the soft monomer to the hard monomer in the core monomer mixture is preferably 1: 1 to 1: 2.5, more preferably 1: 1.2 to 1: 2.0. The content of the carboxylic acid monomer in the core monomer mixture is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, and most preferably 4 to 8 parts by weight per 100 parts by weight of the core monomer mixture. If the content of the carboxylic acid monomer in the core monomer mixture is more than 10 parts by weight per 100 parts by weight of the core monomer mixture, the viscosity of the starch-based copolymer constituting the core may increase relatively and the formation of the coating film may not be smooth. In addition, the content of the chain transfer agent in the core monomer mixture is preferably 0.01 to 1 part by weight per 100 parts by weight of the core monomer mixture, more preferably 0.1 to 0.8 parts by weight in view of the speed control and stability of the polymerization reaction.

In the present invention, the shell consists of a copolymer formed by polymerization of a shell monomer mixture on the core. The shell monomer mixture used to form the copolymer constituting the shell in the present invention comprises a hard monomer and a soft monomer. The concrete contents of the hard monomer and the soft monomer are the same as those described in the core, and thus are omitted. In addition, the shell monomer mixture may preferably further comprise a carboxylic acid monomer or a chain transfer agent. The concrete contents of the carboxylic acid monomer or chain transfer agent are the same as those described in the core, and therefore are omitted. The weight ratio of the hard monomer, soft monomer, carboxylic acid monomer or chain precursor used to form the copolymer constituting the shell of the present invention is such that the glass transition temperature of the starch-based polymer particles of the core- But the present invention is not limited to such an extent that the range is satisfied. For example, the weight ratio of soft monomer to hard monomer in the shell monomer mixture is preferably from 1: 0.2 to 1: 1.0, more preferably from 1: 0.4 to 1: 0.8. In addition, the content of the carboxylic acid monomer in the shell monomer mixture is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, per 100 parts by weight of the shell monomer mixture. In addition, the content of the chain transfer agent in the shell monomer mixture is preferably 0.01 to 1 part by weight per 100 parts by weight of the shell monomer mixture, more preferably 0.1 to 0.8 parts by weight in view of the speed control and stability of the polymerization reaction.

The method for preparing a starch-based polymer particle water-based emulsion used as a main component of an adhesive for synthetic leather production according to the present invention comprises the steps of: preparing a starch hydrolyzate containing starch hydrolyzate; A step of preparing a core comprising a starch-based copolymer; And forming a shell on the core, and may preferably further comprise a post-treatment step for removing unreacted monomers.

The step of preparing a starch lysate containing starch hydrolyzate consists of adding a starch hydrolyzing enzyme to the starch suspension and decomposing the starch under predetermined pH and temperature conditions. At this time, the decomposition of the starch can be carried out by a batch-cooking or a jet-cooking method, and it is preferable to obtain a starch liquefied liquid containing starch hydrolyzate by the intermittent method. The intermittent method may be performed by reacting starch and starch degrading enzyme at 50 to 150 ° C, preferably 80 to 120 ° C for 30 to 300 minutes, preferably 60 to 200 minutes. The starcholytic enzyme includes alpha-amylase, beta-amylase, gluco-amylase, iso-amylase and the like, preferably mesophilic alpha-amylase or heat resistant alpha-amylase. The above starcholytic enzyme is commercially available. For example, when starch hydrolysis is carried out by the intermittent method, the pH of the starch suspension is preferably adjusted to a range of 4 to 8, and the amount of the starch degrading enzyme is 0.001 to 10 parts by weight , Preferably 0.01 to 1 part by weight, although it is not particularly limited.

The core of the starch-based copolymer may be prepared by adding an emulsifier to the starch liquefied liquid, mixing the mixture, adding a core monomer mixture and a polymerization initiator to the starch-based copolymer, and further performing a polymerization reaction. have. An emulsion containing a core consisting of a starch-based copolymer can be obtained by the manufacturing step of the core. At this time, the starch hydrolyzate preferably has a dextrose equivalent (DE) value of 1 to 50. In addition, the core monomer mixture further comprises a hard monomer and a soft monomer, preferably a carboxylic acid monomer or chain transfer agent having an ethylenically unsaturated bond. Further, it is preferable that the core monomer mixture is formulated such that the glass transition temperature of the starch-based polymer particles of the core-shell structure is 5 to 25 캜. In the present invention, the glass transition temperature of the starch-based polymer particles of the core-shell structure can be designed according to the kind and content of the monomers forming the core and the kind and content of the monomers forming the shell. For example, Is expressed by the following equation (1).

[Equation 1]

_{Twt / Tg = {(Wt 1} / Tg 1) + (Wt 2 / Tg 2) + (Wt 3 / Tg 3) + ··· + (Wt n / Tg n)}

In Equation 1 Twt (gross) = ₍₁ + Wt + Wt ₂ (Wt Wt + ₃ + ··· _n)

In equation 1 is the total Tg glass transition temperature, Tg _1, Tg _2, Tg _3, ···, Tg _n are the individual glass transition temperature, it is an absolute temperature unit of the total of the glass transition temperature and the individual transition temperature (K) to be.

Examples of the glass transition temperature design according to the kind and amount of the monomers constituting the copolymer by the above-mentioned formula (1) are shown in Table 1 below.

Raw material name  Tg (占 폚) Weight% (wt) Styrene 100 10 Methyl methacrylate 105 20 Acrylic acid 106 5 2-hydroxyethyl methacrylate 55 25 Glycidyl methacrylate 41 40 Sum 100

The theoretical glass transition temperature of the copolymer obtained by polymerizing the raw materials designed in Table 1 is 64.27 ° C. In this way, the monomers can be formulated such that the glass transition temperature of the starch-based polymer particles of the core-shell structure is between 5 and 25 ° C.

The polymerization initiator used in the polymerization reaction of the present invention may be a thermal decomposition initiator or an oxidation-reduction initiator capable of radical polymerization, and examples thereof include sodium persulfate, potassium persulfate, t-butyl hydroperoxide, Azobisbutyronitrile, 2,2'-azobis-2-methylbutyronitrile, cumene hydroperoxide and the like can be used, and preferable examples include sodium persulfate, potassium persulfate, t-butyl hydroperoxide Or the like may be used. If necessary, a reducing agent such as ascorbic acid, sodium formaldehyde sulfoxylate, sodium bisulfite and the like may be added. The polymerization initiator may be added before the addition of the monomer or may be added at the same time as the monomer. The amount thereof may be in the range of 0.1 to 8 parts by weight, preferably 0.2 to 5 parts by weight, per 100 parts by weight of the core monomer mixture. When the content of the polymerization initiator is less than 0.1 parts by weight per 100 parts by weight of the core monomer mixture, it may take more time to polymerize, and when it exceeds 8 parts by weight, browning of the emulsion including the obtained core may be caused and discolored.

The polymerization reaction temperature, the polymerization reaction pressure and the polymerization reaction time are not particularly limited in the production step of the core, and are, for example, from 60 to 100 ° C, preferably from 70 to 90 ° C, from 0.01 to 10 bar, At a pressure of 5 bar for 20 to 120 minutes, preferably 30 to 90 minutes. The reaction product obtained by the polymerization reaction is aged for minimizing unreacted monomers and for progressing a sufficient polymerization reaction. The aging temperature is kept the same as the polymerization reaction temperature, and the aging time is not limited to a great extent. By aging the reaction product, a core made of a starch-based copolymer and an emulsion containing the same can be obtained.

The step of forming the shell on the core may include a step of adding a shell monomer mixture and a polymerization initiator to the emulsion containing the core and performing a polymerization reaction, and further, a step of further aging. Wherein the shell monomer mixture comprises a hard monomer and a soft monomer, and further comprises a carboxylic acid monomer or chain transfer agent preferably having an ethylenically unsaturated bond. It is also preferable that the shell monomer mixture be formulated so that the glass transition temperature of the starch-based polymer particles of the core-shell structure is 5 to 25 占 폚. The weight ratio of the core monomer mixture to the shell monomer mixture is preferably from 1: 1.5 to 1: 3.5, more preferably from 1: 2 to 1: 3, in order that the glass transition temperature of the core- 3 is more preferable. On the other hand, when the shell monomer mixture is added to the shell monomer mixture in the emulsion containing the core, the shell monomer mixture is preferably added in the form of a pre-emulsion. The pre-emulsion of the cell monomers can be formed by dissolving the emulsifier in water and then adding the shell monomer mixture thereto. In general, emulsion polymerization using a pre-emulsion is known to have an advantage of minimizing the amount of emulsifier used. In the present invention, when the shell monomer mixture is added in the form of a pre-emulsion, not only the amount of emulsifier used is minimized but also the occurrence of aggregates is minimized The productivity can be improved. The polymerization reaction temperature, the polymerization reaction pressure and the polymerization reaction time in the shell formation step are not particularly limited, and are, for example, from 60 to 100 ° C, preferably from 70 to 90 ° C, from 0.01 to 10 bar, At a pressure of 5 bar for 60 to 240 minutes, preferably 90 to 180 minutes. The reaction product obtained by the polymerization reaction is aged for minimizing unreacted monomers and for progressing a sufficient polymerization reaction. The aging temperature is kept the same as the polymerization reaction temperature, and the aging time is not limited to a great extent. By aging the reaction product, starch-based polymer particles of core-shell structure and an emulsion containing the same can be obtained.

The emulsion containing the starch-based polymer particles of the core-shell structure obtained by the formation of the core and shell is then cooled to 45-65 캜 and preferably post-treated to remove unreacted monomers. The post-treatment step for removing unreacted monomers can be carried out by a chemical method, a wet-removing method, or a high-temperature steam method, and is preferably carried out by a chemical method using an oxidizing agent and a reducing agent. The post-treatment step using the oxidizing agent and the reducing agent consists of adding an oxidizing agent and a reducing agent to the emulsion containing the starch-based polymer particles of the core-shell structure to induce oxidation and reduction reaction and aging. At this time, t-butyl hydroperoxide, cumene hydroperoxide and the like can be used as the oxidizing agent. Examples of the reducing agent include sodium hydrosulfite, sodium metabisulfite ) Can be used. The amount of the oxidizing agent and the reducing agent used in the post-treatment step is not particularly limited, and may be, for example, 0.001 to 1 part by weight, preferably 0.002 to 0.8 part by weight per 100 parts by weight of the emulsion. In the post-treatment step, the oxidation reaction and the reduction reaction may be carried out at about 40 to 60 DEG C for 10 to 100 minutes, preferably 20 to 40 minutes. In addition, the emulsion subjected to the oxidation reaction and the reduction reaction is aged to induce a sufficient reaction between the oxidizing agent and the reducing agent and the unreacted monomer. The aging is carried out at about 40 to 60 DEG C for 30 to 150 minutes, preferably 40 to 100 minutes .

The solid content of the starch-based polymer particle water-based emulsion used as the main component in the adhesive for synthetic leather production according to the present invention can be selected from various ranges depending on the manufacturing process conditions of the starch-based polymer particle water-based emulsion, Is preferably 40 to 60% by weight, more preferably 45 to 55% by weight, based on the total weight of the emulsion. The glass transition temperature of the starch-based polymer particles constituting the starch-based polymer particle aqueous emulsion is preferably 5 to 25 캜, more preferably 10 to 20 캜. The content of the starch-based polymer particle water-based emulsion in the adhesive for synthetic leather production is not particularly limited, but the adhesive strength between the fiber layer (for example, fiber fabric) and the surface layer (for example, synthetic resin foam) It is preferably 5 to 90% by weight, more preferably 30 to 80% by weight, most preferably 50 to 70% by weight, based on the total weight of the composition in consideration of the prevention of yellowing of leather and the softness of synthetic leather Do. When the content of the starch-based polymer particle water-based emulsion in the adhesive for synthetic leather production is less than 5% by weight based on the total weight of the composition, the eco-friendliness may deteriorate and the softness of the synthetic leather may be deteriorated. There is a possibility that the strength is lowered or yellowing may occur.

adhesion Reinforcing agent

In the adhesive for synthetic leather production according to the present invention, the adhesion reinforcing agent is a component which conflicts with the degradation of the bonding strength when only the starch-based polymer particle water-based emulsion is used and is compatible with the starch-based polymer particle waterborne emulsion, The kind of the adhesive can be selected from the known adhesive component for synthetic leather production, as long as it can improve the bonding strength between the surface layer (e.g., the fiber fabric) and the surface layer (e.g., the foam of synthetic resin). For example, the adhesive reinforcing agent may be composed of at least one selected from an ethylene-vinyl acetate copolymer resin or a polyurethane resin, and the starch-based polymer particle water-based emulsion used as a main component in the adhesive for synthetic leather production according to the present invention It is preferable to use at least one selected from the group consisting of an ethylene-vinyl acetate copolymer aqueous emulsion and a polyurethane aqueous emulsion. In view of the synergistic effect of the two components, the ethylene-vinyl acetate copolymer aqueous emulsion and the ethylene- And a combination of polyurethane water-based emulsions. Of these, ethylene-vinyl acetate copolymer aqueous emulsions are commercially available. The polyurethane which is a constituent component of the polyurethane water-based emulsion is preferably a modified polyurethane for enhancing the adhesive strength and improving the water-dispersibility, and is preferably an anionic aliphatic polyester-based polyurethane, for example. Water-based emulsions of anionic, aliphatic polyester-based polyurethanes are commercially available. When the adhesive reinforcement is composed of a combination of an ethylene-vinyl acetate copolymer aqueous emulsion and a polyurethane water-based emulsion, the weight ratio of the ethylene-vinyl acetate copolymer aqueous emulsion to the polyurethane water-based emulsion is 1: 9 to 9: 1 More preferably from 2: 8 to 8: 2, most preferably from 4: 6 to 6: 4. The solid content of the ethylene-vinyl acetate copolymer aqueous emulsion is preferably 50 to 70% by weight, more preferably 55 to 65% by weight, based on the total weight of the emulsion, considering ease of application of the synthetic leather- Is more preferable. The solid content of the polyurethane water-based emulsion is preferably 50 to 70% by weight, more preferably 55 to 65% by weight, based on the total weight of the emulsion, considering ease of application of the synthetic leather-forming adhesive and ease of drying Do. The content of the adhesive reinforcing agent in the synthetic leather-forming adhesive is not particularly limited, but is preferably 10 to 70% by weight, more preferably 20 to 60% by weight, more preferably 30 to 60% by weight, Most preferably 50% by weight.

Viscosity modifier

In the adhesive for synthetic leather production according to the present invention, the viscosity adjusting agent is a component for controlling the viscosity of the adhesive for synthetic leather production and further improving the rheological properties, and if it is compatible with the starch-based polymer particle water-based emulsion, But is not limited to a large extent. In view of compatibility with the starch-based polymer particle water-based emulsion, the viscosity controlling agent in the present invention is preferably water-soluble or water-dispersible, and examples thereof include hydroxyethyl cellulose, hydroxypropyl methylcellulose, modified urethane, modified polyether, Copolymer and the like, and is preferably a polyether water-based emulsion modified with urethane. Urethane-modified polyethers can be prepared by the addition reaction of an isocyanate compound with a polyether glycol, and specific examples thereof can be prepared by an addition reaction of polypropylene glycol and naphthalene diisocyanate. Urethane modified polyether shows a repeated structure of hard segment - soft segment and can improve viscosity as well as rheological properties. The urethane-modified polyether water-based emulsion is commercially available. The solid content of the urethane-modified polyether water-based emulsion is preferably 10 to 30% by weight, more preferably 15 to 25% by weight. The content of the viscosity controlling agent in the adhesive for synthetic leather production is not particularly limited, but is preferably 0.1 to 5% by weight, more preferably 0.5 to 4% by weight, more preferably 1 to 5% by weight, By weight to 3% by weight.

Another aspect of the present invention relates to a method for producing synthetic leather using the above-described adhesive for synthetic leather production. The method for producing a synthetic leather according to the present invention comprises the steps of applying a foamable synthetic resin composition to a release paper and foaming to form a surface layer comprising a synthetic resin foam; Applying the synthetic leather-forming adhesive to the upper surface of the surface layer; And placing the fiber fabric on the applied synthetic leather-forming adhesive, heating and drying the fiber fabric, and laminating the fiber fabric on the surface layer. At this time, the foamable synthetic resin composition may be selected from a polyurethane resin composition containing a blowing agent or a polyvinyl chloride resin composition containing a blowing agent. Further, the fiber fabric may be selected from a woven fabric, a woven fabric, or a nonwoven fabric. The synthetic leather-forming adhesive applied on the surface layer is preferably heated and dried at about 180 to 240 DEG C for 10 seconds to 2 minutes, and the synthetic leather-forming adhesive is heated and dried to form the fiber cloth and the surface layer in a state of being laminated .

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are intended to clearly illustrate the technical features of the present invention, and do not limit the scope of protection of the present invention.

One. Starch-based  Polymer particles Emulsion  Produce

Production Example 1-1: Preparation of Starch Liquid Liquid Containing Starch Lysate

55 g of oxidized corn starch (manufacturer: Kobunshi Co., Ltd., Korea) was added to 87.9 g of deionized water and dispersed to prepare a starch suspension. In addition, 1 g of heat-resistant alpha-amylase (Liquozyme supra, Novozyme, Denmark) was diluted with 10 g of deionized water to prepare a starch hydrolyzate solution. Thereafter, the pH of the starch suspension was adjusted to about 6.0, 1.0 g of starch hydrolyzate was added thereto, and the mixture was reacted at about 97 캜 for about 90 minutes. After the reaction was completed, 0.4 g of hypochlorous acid was added to the reaction product to inactivate the enzyme and cooled to about 80 캜 to obtain a starch-liquefied liquid containing starch hydrolyzate. At this time, the dextrose equivalent (DE) value of the starch hydrolyzate was about 25, and the solids concentration of the starch hydrolyzate was about 35%.

Production Example 1-2: Preparation of Core Made of Starch Polymer and Emulsion Containing It

130 g of deionized water and 9.8 g of an anionic emulsifier (trade name: DOWFAX ™ 2A1; supplier: Dow Chemical Company, US) were added to the reactor containing the starch liquefied liquid obtained in Production Example 1-1 and charged with nitrogen. Thereafter, the reactor in a nitrogen atmosphere was heated to about 80 DEG C, and a polymerization initiator solution (a solution in which 1.0 g of potassium persulfate and 0.04 g of sodium persulfate were dissolved in 30.30 g of deionized water), 45.1 g of methyl methacrylate, A copolymer monomer mixture composed of 7.5 g of methacrylic acid, 39 g of 2-ethylhexyl acrylate, 28.8 g of styrene and 7.5 g of n-butyl acrylate was added dropwise over 60 minutes to proceed the copolymerization reaction. After completing the dropwise addition of the polymerization initiator solution and the core monomer mixture, the copolymerization reaction product was agitated at about 80 DEG C for about 30 minutes and aged to obtain a core made of the starch-based polymer and an emulsion containing the same.

Production Example 1-3: Preparation of Shell Monomer Pre-emulsion

5.0 g of an anionic emulsifier (trade name: DOWFAX ™ 2A1; supplied by Dow Chemical Company, US) was added to 130 g of deionized water and then dissolved. Then, 56.3 g of methyl methacrylate, 195.4 g of n-butyl acrylate, And 1.3 g of n-dodecyl mercaptan were slowly added dropwise in this order to prepare a shell monomer pre-emulsion. The prepared preemulsion was stable without layer separation for 24 hours and had a viscosity of about 150 centipoise (cPs).

Production Example 1-4: Preparation of starch-based polymer particles of core-shell structure and emulsion containing the same

The temperature of the reactor containing the emulsion containing the core (obtained in Preparation Example 1-2) was maintained at about 80 占 폚, and to this was added a polymerization initiator solution (3.0 g of potassium persulfate in 91.7 g of deionized water and 3.0 g of sodium bisulfite 0.36 g) and a shell monomer pre-emulsion (obtained in Preparation Example 1-3) were added dropwise for about 180 minutes to carry out a copolymerization reaction on the core surface to form a shell. After completion of the dropwise addition of the polymerization initiator solution and the shell monomer pre-emulsion, the copolymerization reaction product was stirred at about 80 캜 for about 60 minutes and aged to obtain a core-shell structure starch-based polymer particle and an emulsion containing the same. Thereafter, the pH of the emulsion containing the core-shell structure starch-based copolymer particles obtained with ammonia water was adjusted to about 7.0 to obtain a final emulsion. Analysis of the emulsion containing the starch-based polymer particles of the finally obtained core-shell structure showed a solids content of about 50% by weight and a viscosity of 170 cPs (KS M ISO 2555 Test Method, Spindle No # 2 and 60 rpm The aggregate content was about 0.004%. (Aggregate content: The emulsion was sieved through a 200-mesh sieve. The agglomerates were placed in an oven, dried at about 105 ° C for 8 hours, and then weighed (measured by a Brookfield viscometer) , Which is calculated as a percentage of the total amount of the polymer particles). The coating film was formed by coating an emulsion containing the finally obtained starch-based polymer particles having a core-shell structure. The coating film was analyzed by differential scanning calorimetry (DSC) Transition temperature.

2. Manufacture of adhesives used in the manufacture of synthetic leather

Production Example 2

70 parts by weight of an emulsion containing the starch-based polymer particles of the core-shell structure obtained in Preparation Example 1-4, 15 parts by weight of VINNAPAS EP760 (manufacturer: Wacker Chemie AG, Germany) as an adhesive reinforcing agent and 15 parts by weight of Impranil DL 1380 Manufactured by Bayer MaterialScience AG, Germany) and 2 parts by weight of SN-Thickener 622N (supplier: SAN NOPCO KOREA LTD.) As a viscosity modifier were mixed to prepare an adhesive for synthetic leather production.

Production Example 3

60 parts by weight of an emulsion containing the starch-based polymer particles of the core-shell structure obtained in Preparation Example 1-4, 20 parts by weight of VINNAPAS EP760 (manufacturer: Wacker Chemie AG, Germany) as an adhesive reinforcing agent and 20 parts by weight of Impranil DL 1380 Manufactured by Bayer MaterialScience AG, Germany) and 2 parts by weight of SN-Thickener 622N (supplier: SAN NOPCO KOREA LTD.) As a viscosity modifier were mixed to prepare an adhesive for synthetic leather production.

Production Example 4

50 parts by weight of emulsion containing the starch-based polymer particles of the core-shell structure obtained in Preparation Example 1-4, 25 parts by weight of VINNAPAS EP760 (manufacturer: Wacker Chemie AG, Germany) as an adhesive reinforcing agent and 25 parts by weight of Impranil DL 1380 Manufactured by Bayer MaterialScience AG, Germany) and 2 parts by weight of SN-Thickener 622N (supplier: SAN NOPCO KOREA LTD.) As a viscosity modifier were mixed to prepare an adhesive for synthetic leather production.

The technical information of the adhesive reinforcing agent and the viscosity adjusting agent used in Production Examples 2 to 4 is as follows.

* VINNAPAS® EP760: water-based emulsion of an ethylene-vinyl acetate copolymer having a solids content of about 60% by weight

* Impranil® DL 1380: Water-based emulsion of anionic, aliphatic polyester-based polyurethane, with a solids content of about 60%

* SN-Thickener 622N: Water-based emulsion of polyether modified with urethane, with a solids content of about 20%

Comparative Production Example 1

50 parts by weight of a polyvinyl chloride resin, 30 parts by weight of dynomal octyl phthalate (DNOP or DOP) as a plasticizer, 15 parts by weight of calcium carbonate and 5 parts by weight of a defoaming agent were mixed to prepare an adhesive for synthetic leather production.

3. Manufacture of Synthetic Leather

Production Example 5

The foamable polyvinyl chloride resin composition was applied to the release paper and heated at 210 DEG C for about 2 minutes in a Mathis oven and dried to form a foam layer made of polyvinyl chloride foam. Thereafter, a synthetic leather-forming adhesive prepared in Production Example 2 was applied to the upper surface of the foamed layer to a thickness of about 0.12 mm, a white woven fabric was placed on the foamed layer, lightly pressed with a plywood stick, and then dried in a Mathis Oven And then heated and dried at a temperature of 210 캜 for about 45 seconds to prepare a synthetic leather in which a woven fabric was laminated on a foamed layer.

Production Example 6

Synthetic leather in which the woven fabric was laminated to the foamed layer was prepared in the same manner as in Production Example 5, except that the adhesive for synthetic leather production was replaced with the adhesive for synthetic leather production prepared in Production Example 3.

Production Example 7

Synthetic leather in the form of a woven fabric lined with a foam layer was prepared in the same manner as in Production Example 5, except that the adhesive for synthetic leather production was replaced with the adhesive for synthetic leather production prepared in Preparation Example 4.

Comparative Preparation Example 2

Synthetic leather in which the woven fabric was laminated to the foamed layer was prepared in the same manner as in Production Example 5, except that the adhesive for synthetic leather production prepared in Comparative Production Example 1 was used as an adhesive for synthetic leather production.

Comparative Preparation Example 3

Except that an emulsion containing the starch-based polymer particles of the core-shell structure obtained in Preparation Example 1-4 was used as an adhesive for synthetic leather production, and the woven fabric was laminated on the foam layer in the same manner as in Production Example 5 Synthetic leather was prepared.

4. Measurement of physical properties of adhesive for synthetic leather and synthetic leather

(1) Determination of solid content of adhesive for synthetic leather production

The solid content of the adhesive used for laminating the woven fabric to the foam layer in the process of manufacturing the synthetic leather was measured according to the KS M ISO 3251 test method, and the results are shown in Table 2 below.

Adhesive for synthetic leather production Production Example 2 Production Example 3 Production Example 4 Comparative Preparation Example 1 Production Example 1-4 Solid content (% by weight) 54 56 58 96 50

(2) Peeling strength of synthetic leather, failure mode at peeling, yellowing and softness measurement

The peel strengths of the synthetic leather prepared in Production Examples 5 to 7, Comparative Production Examples 2 and 3 were measured according to the KS M 3601 10.5 test method.

In addition, the failure mode was visually observed in the peel strength test. The failure modes are classified into three modes such as adherent failure, cohesive failure, and interface failure. Failure of the adherend is a mode that occurs when the adhesive strength between the adhesive and the adherend is very large. Interfacial failure occurs when the adhesive interface is peeled off, and is generally a mode suitable for an adhesive that is not an adhesive. The cohesive failure refers to the case where the adhesive itself is broken. In the synthetic leather of the present invention, the foam layer and the woven fabric correspond to the adherend.

In addition, during the manufacturing process of the synthetic leather, it was visually observed whether the color of the white woven fabric was changed by the penetration of the adhesive or the like, and the yellowing was judged.

In addition, the softness was sensually evaluated while the synthetic leather was kept pressed by hand. The sensory evaluation was based on a 6 point scale. Specifically, it was rated at 0 points (very hard compared to natural leather) and 5 points (showing softness similar to natural leather) based on natural leather.

Table 3 below shows the peel strength of synthetic leather, the failure mode upon peeling, the degree of yellowing and the result of measurement of softness.

Synthetic leather division Production Example 5 Production Example 6 Production Example 7 Comparative Production Example 2 Comparative Production Example 3 Peel strength (kgf) 1.6 1.7 1.7 1.7 0.4 Destruction mode Destroyed material Destroyed material Destroyed material Destroyed material Interfacial failure Yellowing none none none none Occur Softness 5 5 5 3 4

As shown in Table 3, the synthetic leathers prepared using the adhesives of Production Examples 2 to 4 of the present invention were compared with the synthetic leathers produced using the polyvinyl chloride resin-based adhesive (Comparative Production Example 1) Adhesion strength and failure mode were similar or the same, no yellowing occurred, and the softness was better than that of natural leather. On the other hand, when synthetic leather was produced using only an emulsion containing starch-based polymer particles of a core-shell structure as an adhesive, all of the properties showed poor results.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the scope of protection of the present invention is not limited to the specific embodiments but should be construed as including all embodiments belonging to the claims attached hereto.

Claims (14)

A composition comprising a starch-based polymer particle water-based emulsion, an adhesive reinforcing agent and a viscosity control agent,
Wherein the starch-based polymer particles comprise a core consisting of a starch-based copolymer formed by polymerization of a core monomer mixture comprising a starch degradation product and a hard monomer and a soft monomer; And a shell formed of a copolymer formed on the core by polymerization of a shell monomer mixture comprising a hard monomer and a soft monomer, wherein the core-
Wherein the hard monomer has an ethylenic unsaturated bond and the homopolymer has a glass transition temperature of from 30 캜 to 250 캜,
Wherein the soft monomer has an ethylenic unsaturated bond and the homopolymer has a glass transition temperature of from 10 캜 to -80 캜,
Wherein the viscosity modifier is a urethane-modified polyether water-based emulsion.
The synthetic leather-making adhesive according to claim 1, wherein the starch-based polymer particle water-based emulsion has a solid content of 40 to 60% by weight.
The synthetic leather-making adhesive according to claim 1, wherein the glass transition temperature of the starch-based polymer particles is 5 to 25 ° C.
The synthetic leather-making adhesive according to claim 1, wherein the content of the starch-based polymer particle water-based emulsion is 5 to 90% by weight based on the total weight of the composition.
The adhesive for synthetic leather production according to claim 1, wherein the adhesive reinforcement is at least one selected from the group consisting of an ethylene-vinyl acetate copolymer aqueous emulsion and a polyurethane water-based emulsion.
6. The method of claim 5, wherein the adhesive reinforcement comprises a combination of an ethylene-vinyl acetate copolymer aqueous emulsion and a polyurethane water emulsion, wherein the weight ratio of the ethylene-vinyl acetate copolymer aqueous emulsion to the polyurethane aqueous emulsion is from 1: 9 to 9 Lt; RTI ID = 0.0 > 1 < / RTI >
7. The adhesive for the production of synthetic leather according to claim 6, wherein the solid content of the ethylene-vinyl acetate copolymer aqueous emulsion is 50 to 70% by weight and the solid content of the polyurethane water-based emulsion is 50 to 70% by weight.
The adhesive of claim 1, wherein the content of the adhesive reinforcement is 10 to 70% by weight based on the total weight of the composition.
delete delete The synthetic leather-making adhesive according to claim 1, wherein the solid content of the urethane-modified polyether water-based emulsion is 10 to 30% by weight.
The adhesive of claim 1, wherein the viscosity modifier is present in an amount of 0.1 to 5% by weight based on the total weight of the composition.
Applying a foamable synthetic resin composition to the release paper and foaming it to form a surface layer composed of a synthetic resin foam;
Applying the synthetic leather-forming adhesive according to any one of claims 1 to 8, 11 and 12 to the upper surface of the surface layer; And
A step of placing the fiber fabric on the applied adhesive for making synthetic leather, heating and drying the fiber fabric, and laminating the fiber fabric on the surface layer.
14. The method for producing a synthetic leather according to claim 13, wherein the foamable synthetic resin composition is a polyurethane resin composition comprising a polyvinyl chloride resin composition or a foaming agent containing a foaming agent.