KR100541993B1 - A water-based acryl polyurethan binder for leather and a manufacturing method thereof - Google Patents

Abstract

A water-based acrylic polyurethane prepolymer for leather is obtained by reacting an acrylic polyol having a number average molecular weight of 800 to 6000 and a hydroxyl value of 55 to 210 with a polyisocyanate and a carboxyl group-containing diol and triol, which is chain-extended with a crosslinking agent to be a water-based acrylic for leather. Provided is a method of making a polyurethane binder.

The water-based acrylic polyurethane binder for leather is particularly excellent in touch sensitivity, adhesive strength, hiding power characteristics when used as a binder for natural leather and fibers, and has excellent wear and water resistance and pigment miscibility.

Description

Aqueous acrylic polyurethane binder for leather and manufacturing method therefor {A WATER-BASED ACRYL POLYURETHAN BINDER FOR LEATHER AND A MANUFACTURING METHOD THEREOF}

The present invention relates to an aqueous acrylic polyurethane binder for leather, and more particularly, after reacting an acrylic polyol having a number average molecular weight of 800 to 6000 and a hydroxyl number of 55 to 210 with a polyisocyanate, a carboxyl group-containing diol and a triol, It relates to a water-based acrylic polyurethane binder for leather produced by a method of chain extension using a crosslinking agent.

In recent years, ecological factors and government regulatory policies have played an important role in the development of coating technology. An important environmental issue relates to methods of reducing or even completely removing volatile organic compounds (VOCs) commonly used in coating compositions. Due to these problems, interest in waterborne and powder coatings is increasing in recent coating technology developments. Examples of such coatings are water dispersible urethanes, acrylics, alkyds and epoxy resins.

Polyurethanes are very important in the coatings industry because of their excellent properties. Recently, two-component aqueous polyurethane systems have been developed for various coating applications, of which thermoplastic polyurethane acrylic hybrid dispersions have received considerable attention. Hybrid dispersions have the advantage that their properties can be easily adjusted according to the mixing ratio as compared to pure urethane dispersions or pure acrylic dispersions. However, the urethane-acrylic hybrid dispersion simply kneading the acrylic dispersion and the urethane dispersion has insufficient physical properties such as adhesion when used for coating, and especially when used for leather, hides scratches on the surface of the raw material, which is the value of leather. The hiding power to maintain the low, there is a problem that the touch sensitivity of the user, which is a problem when using the leather in particular clothing is not good.

For these reasons, techniques have been developed to improve the physical and chemical properties of dispersions that are simply kneaded urethane acrylic hybrids.

U.S. Patent 5,173,526 discloses (a) preparing a carboxy containing water dispersible isocyanate terminated polyurethane prepolymer, and (b) adding a vinyl monomer mixture to this carboxy containing water dispersible isocyanate terminated polyurethane prepolymer to provide a prepolymer / monomer mixture. After preparation, (c) tertiary amine is added to the prepolymer / monomer mixture, (d) the prepolymer / monomer mixture is dispersed in water, and (e) oil soluble free radical initiators and chains. A method of preparing an aqueous polyurethane-vinyl polymer (hybrid) coating composition is disclosed by adding an extender to the aqueous dispersion, (f) completing the chain expansion reaction, and then heating the aqueous dispersion to polymerize the vinyl monomers. Doing. Various examples of vinyl monomers suitable for hybridization include lower alkyl (C1-C6) esters of acrylic acid or methacrylic acid.

U. S. Patent No. 5,331, 039 discloses a coating composition comprising a water dispersible binder composition comprising two different water dispersible polyol polymers and a polyisocyanate component dispersed therein. One of the water dispersible polymers is polyester; Or polyester resins containing urethane, carboxyl and / or hydroxyl groups, the other being polyester grafted with hydroxy acryl which can crosslink with hydrophilic polyisocyanates emulsified in water; Or hydroxylated polyacrylics.

European patent application EP 0562 282 A1 discloses an aqueous dispersion of (A) an acrylic polymer comprising 2 to 4% of hydroxy groups and an aliphatic polyurethane resin and (B) a low volatility of liquid aliphatic polyisocyanate usually incorporated in a solvent. A two-component aqueous varnish based on a mixture is disclosed. The acrylic / polyurethane ratio is 60/40, and the acrylic content is 15-18% of the dispersion.

Korean Patent No. 203561 discloses a) preparing a carboxy-containing water dispersible isocyanate terminated polyurethane prepolymer, and b) one or more acrylic monomers (preferably comprising hydroxy groups). To form a prepolymer / monomer mixture, c) add tertiary amines to the prepolymer / monomer mixture, d) add hydroxy functional acrylic monomers in the presence of other materials, in particular methacryl esters, e ) Disperse this prepolymer / monomer mixture in water, f) add an soluble free radical initiator and a hydroxy-containing chain extender to this aqueous dispersion, and g) react with the polyurethane chain to this aqueous dispersion. Adding a chain terminator, such as an alkanolamine, to terminate growth of its length, h) Optionally, to this mixture is added a chain transfer agent, which limits the molecular weight of the vinyl polymer during the polymerization reaction, i) heating this aqueous dispersion to polymerize the acrylic monomers and completing the chain expansion reaction of the prepolymer, then j ) A water-based crosslinkable polyurethane / acrylic system prepared by mixing the prepared hybrid dispersion with a water dispersible polyisocyanate.

However, the urethane-acrylic hybrid dispersion as described above is not only complicated in the manufacturing method but also improved in touch sensitivity and hiding power, which is particularly important in leather. Therefore, there has been a demand for a method capable of producing a hybrid dispersion which has excellent physical and chemical properties and is manufactured by a simpler method and which is excellent in touch sensitivity and silver penetrating force.

It is an object of the present invention to provide a process for producing an aqueous acrylic polyurethane binder for leather by a simplified process.

Another object of the present invention is to provide an aqueous acrylic polyurethane binder for leather having good hiding power, touch sensitivity, and pigment miscibility according to the present method.

The inventors have found that the above object can be achieved by using a water-based acrylic polyurethane for leather produced using the method according to the invention.

Therefore, the present invention,

Reacting an alkyl acrylic polyol having a number average molecular weight of 800 to 6000 and a hydroxyl value of 55 to 210 with a diol and a triol containing a polyisocyanate and a carboxyl group to obtain a prepolymer having N = C═O of 3 to 5%; And

Chain extending with a crosslinking agent;

It is a water-based acrylic polyurethane binder manufacturing method for leather.

The present invention relates to a water-based acrylic polyurethane binder for leather produced using the above method in one aspect.

In one embodiment of the invention, the acrylic polyol is preferably used by polymerizing hydroxyalkyl acrylate or hydroxyalkyl methacrylate (hereinafter referred to as hydroxyalkyl (meth) acrylate). Here, alkyl of hydroxyalkyl (meth) acrylate is C1-C8 alkyl, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate. .

In an embodiment according to the present invention, the acrylic polyol may be used by copolymerizing hydroxyalkyl (meth) acrylate with alkyl (meth) acrylate. Preferred alkyl (meth) acrylates are alkyl methacrylates having C 1 -C 10 alkyl groups, for example n-ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, cyclohexyl Acrylate, ethylhexyl acrylate, hexanediol diacrylate or mixtures thereof.

In one embodiment according to the invention, the acrylpolyols can be used in combination with acrylpolyols and conventional polyols of low molecular weight, preferably 800-6000. The polyols that may be used as the conventional polymeric polyols may be any compound in the polyol compound group. In particular, these polyols can be polyester polyols, polyether polyols, polythioether polyols, polycarbonate polyols, polyacetal polyols, polyolefin polyols or polysiloxane polyols.

If the molecular weight and hydroxyl value of the acrylic polyol used according to the present invention is too high, the reaction viscosity becomes very high during the reaction, gelation may occur, and if the molecular weight and hydroxyl value are too low, the elongation and touch sensitivity of the final product Becomes bad. In an embodiment of the present invention, the molecular weight of the acrylic polyol is preferably 800-6000 and the hydroxyl value is preferably 55-210. More preferably, the molecular weight is 1000-3000, and the hydroxyl value is preferably 55-150.

Examples of such polyisocyanates that can be used to prepare the prepolymers according to the invention include aliphatic, cycloaliphatic, aromatic aliphatic or aromatic polyisocyanates. Examples of suitable polyisocyanates include isophorone diiso cyanate, cyclohexane-1, 4-diisocyanate, 4, 4'-dicyclohexylmethane diiso cyanate, 3, 3-dimethyl-4, 4-di (amino Cyclohexyl) methane, hexamethylene diiso cyanate, dodecamethylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenyl Methane diisocyanate, 2,4-diphenylmethane diisocyanate, xylene diisocyanate, 1,4-diisocyanatobenzene, polymethylene polyphenyl polyisocyanate and 1,5-naphthalene diisocyanate. Such isocyanates are commonly used in the preparation of polyurethane prepolymers. Polyisocyanate mixtures may also be used. In addition, isocyanurate, biurets of the material can also be used to prepare the prepolymer.

In the prepolymer according to the present invention, it is preferable to mix the acrylic polymer and the polyisocyanate such that NCO% is maintained at 3-5%. When the NCO content of the prepolymer is low, the coating film becomes sticky and a lot of surface adhesive force is generated, and the touch sensitivity is bad, and when the NCO content is higher than the above range, the film is formed too hard and the touch sensitivity is worsened.

The prepolymer according to the present invention has water dispersibility, which is imparted to the polyurethane prepolymer through a reactive compound having an acid group. These compounds preferably include carboxyl group-containing diols and triols, with the preferred carboxy-containing diols being 2,2-dimethylpropionic acid. In the practice of the invention, the 2,2-dimethylpropionic acid preferably contains 3 to 5% by weight in consideration of the dispersibility to water and storage stability.

The chain extender which can be used in the practice of the present invention preferably uses a conventional amine compound, and the amine compound includes isophoronediamine, hexamethylenediamine, ethylenediamine, noborandadiamine, triethyldiamine and the like.

The water-based acrylic polyurethane prepolymer for leather of the present invention may be obtained by kneading an acrylic polyol and dimethylpropionic acid, adding a solvent and a catalyst to the kneaded product, heating the mixture, and heating the polyisocyanate polymer. Conventional catalysts used for preparing the aqueous polyurethane prepolymers can be used, with dibutyltindilaurate being preferred.

The following examples illustrate the invention.

Example

Example 1.

Four-necked plastics were equipped with a reflux tube and a stirrer, purged with nitrogen, and then 268 g of acryl polyol (MW 3500, OHV = 57) using 2-ethylhexyl acrylate, 18 g of dimethylpropionic acid, and catalyst dibutylthiaraudi After mixing 0.031 g of the rate with 96 g of normal methylpyrrolidone, it heated up to 110 degreeC under nitrogen, and dehydrated for 40 minutes. After dehydration, 54 g of toluene diisocyanate was added at 90 ° C. to prepare a prepolymer after the reaction for 5 hours.

Example 2.

110 g of acrylic polyol (MW 3500, OHV = 57) using 2-ethylhexyl acrylate, 158 g of acrylic polyol (MW 2500, OHV = 185) using butyl acrylate, 18 g of dimethylpropionic acid, 0.31 dibutyltin dilaurate g and 96 g of normal methylpyrrolidone were added, and it heated up at 110 degreeC under nitrogen, and dehydrated for 40 minutes. After dehydration, 54 g of toluene diisocyanate was added at 90 ° C. to prepare a prepolymer after the reaction for 5 hours.

Example 3.

158 g of acrylic polyol (MW 2500, OHV = 185) using butyl acrylate, 115 g of polyester polyol MW 2500, 18 g of dimethylpropionic acid, 0.31 g of dibutyltin dilaurate, and 109 g of normal methylpyrrolidone were added thereto, followed by nitrogen. It heated up to 110 degreeC under water, and dehydrated for 40 minutes. After dehydration, 54 g of toluene diisocyanate was added at 90 ° C to prepare a prepolymer after the reaction for 5 hours.

Example 4.

110 g of acrylic polyol (MW 2500, OHV = 185) with butyl acrylate, 42 g of acrylic polyol (MW 2200, OHV = 89) with butyl acrylate, 103 g of polyetherpolyol MW3000 and 18 g of dimethylpropionic acid, dibutyl 0.31 g of tindilaurate and 109 g of normal methylpyrrolidone were thrown in, and it heated up at 110 degreeC under nitrogen, and dehydrated for 40 minutes. After dehydration, 62 g of toluene diisocyanate was added at 90 ° C. to prepare a prepolymer after the reaction for 5 hours.

Example 5.

0.12% by weight of diamine was added to the obtained water-based acrylic polyurethane prepolymer of Examples 1, 2, 3, and 4 to obtain a desired solid content with sufficient vigorous stirring. In the above experiments, 30% by weight of solids were made, respectively.

Comparative Example 1.

A water-soluble urethane (product name 50UD manufactured by Bayer Germany) and an acrylic dispersion product (CA-1837 manufactured by KFTECH Korea) were mixed at a ratio of 2: 5 to prepare an acrylic-urethane hybrid dispersion having a solid content of 30%.

 Each physical property is shown in Table 1.

Final product Exterior Elongation Viscosity (25 ℃) Example 1 of Example 5 Translucent 1420% 73 cps Example 2 of Example 5 Translucent 1270% 62 cps Example 3 of Example 5 Translucent 920% 50 cps Example 4 of Example 5 Translucent 1110% 55 cps Comparative Example 1 Translucent 1100% 70 cps

* Viscosity does not change significantly in both test samples.

Each of the products obtained was added sequentially, as shown in Table 2, mixed, and coated on natural leather.

A B C D E Example 1 of Example 5 70 - - - - Example 2 of Example 5 - 70 - - - Example 3 of Example 5 - - 70 - - Example 4 of Example 5 - - - 70 - Comparative Example 1 - - - - 70 Pigment paste 20 20 20 20 20 Thickener One One One One One Humectant One One One One One water 8 8 8 8 8

At this time, the natural leather is cut to sheep and cowhide horizontally and vertically 30 cm in length, the coating was used for the spray method. The number of coatings and the process were carried out as follows.

Primary spray → primary drying (10 seconds at 80 ° C) → primary iron (80 ° C)

Secondary spray → Secondary drying (10 seconds at 80 ° C) → Secondary iron (80 ° C)

3rd spray → 3rd drying (10 seconds at 80 ° C) → milling (3 hours)

Adhesion, hiding power, touch sensitivity, and the like of the coated leather products were considered.

The hiding power was measured by KS M 5000-3111, and the adhesion was measured by visually observing the surface state after attaching the cellophane tape to the coating surface. The touch sensitivity was sampled by 50 adult men and women and tested. Table 3 shows each result.

division Concealment rate (white / red yellow) Adhesion Touch sensitivity A 0.98 / 0.75 ○ ○ B 0.97 / 0.73 ○ ○ C 0.98 / 0.80 ○ ◎ D 0.97 / 0.76 ○ ○ E 0.90 / 0.56 △ △

Remarks: ◎ Very good, ○ Excellent, △ Normal. ▽ bad.

The hiding power was measured by the hiding rate according to KS M 5000-3111. The hiding rate is the ability to cover the difference of the background color and hides it. .

Comparative Example 2.

Four-necked plastics were equipped with a reflux tube and a stirrer, purged with nitrogen, and then 268 g of acryl polyol (MW 3500, OHV = 57) using 2-ethylhexyl acrylate, 32 g of dimethylpropionic acid, and catalyst dibutyl thiaraudi 0.31 g of the rate was mixed with 96 g of normal methylpyrrolidone, and then heated to 110 ° C under nitrogen, and dehydrated for 40 minutes. After dehydration, 54 g of toluene diisocyanate was added at 90 ° C. to prepare a prepolymer after the reaction for 5 hours. In this case, there was no change in the prepolymer. After solubilization it gelled with high viscosity.

Comparative Example 3.

Four-necked plastics were equipped with a reflux tube and a stirrer and purged with nitrogen, followed by 420 g of acryl polyol (MW 3500, OHV = 57) using 2-ethylhexyl acrylate, 29 g of dimethylpropionic acid, and catalyst dibutyl thiaraudi After mixing 0.3 g of rate 0.31 g of normal methyl pyrrolidone, it heated up at 110 degreeC under nitrogen, and dehydrated for 40 minutes. After dehydration, 54 g of toluene diisocyanate was added at 90 ° C. to prepare a prepolymer after the reaction for 5 hours. Gelled during prepolymer reaction.

Comparative Example 4.

Four-necked plastics were equipped with a reflux tube and agitator, purged with nitrogen, and then 110 g of acrylic polyol (MW 2500, OHV = 185) using butyl acrylate, 162 g of acrylic polyol (MW 2000), and polyester polyol (MW). 3500) 138 g, 28 g of dimethylpropionic acid, and 0.031 g of catalytic dibutyl thiarlaudirate were mixed with 96 g of normal methylpyrrolidone, and then heated to 110 ° C. under nitrogen and dehydrated for 40 minutes. After dehydration, 54 g of toluene diisocyanate was added at 90 ° C. to prepare a prepolymer after the reaction for 5 hours. In this case, the viscosity was very high during the reaction, making it difficult to proceed with the reaction.

According to the present invention, there is provided a simplified manufacturing method for producing a water-based acrylic polyurethane binder for leather and an aqueous acrylic polyurethane binder for leather having excellent physical and chemical properties. The water-based acrylic polyurethane binder for leather is provided with a water-based acrylic polyurethane binder having good hiding power, touch sensitivity, compatibility with pigments, and excellent adhesive properties.

Claims (3)

At least one polyol compound selected from the group consisting of an acrylic polyol having a number average molecular weight of 800 to 6000 and a hydroxyl value of 55 to 210, a polyester polyol and a polyether polyol, an isocyanate component composed of a toluene diisocyanate compound, and a carboxyl group Reacting dimethylpropionic acid as one diol to obtain a prepolymer having an NCO content of 3-5%; And Chain extending with a crosslinking agent; Aqueous acrylic polyurethane binder manufacturing method for leather comprising a. The method of claim 1, wherein the carboxyl group-containing diol is 2,2-dimethylpropionic acid. A water-based acrylic polyurethane binder for leather produced by the method of claim 1.