KR102553862B1 - Coating composition for leather comprising polyaspartic urea and urethane - Google Patents

Abstract

The present invention relates to a leather coating composition for forming a coating layer on the surface of a leather product made of natural leather, synthetic leather, or artificial leather, and includes a main component including a urethane prepolymer, an isocyanate compound, and a silane compound, and polyaspartate , It relates to a leather coating composition comprising a curing agent containing aminosilane and forming a coating layer with improved durability to exhibit physical properties suitable for surface coating of shoes among leather products, in particular, sports shoes.

Description

Composition for leather coating containing polyaspartic urea and urethane {COATING COMPOSITION FOR LEATHER COMPRISING POLYASPARTIC UREA AND URETHANE}

The present invention relates to a composition for coating leather containing polyaspartic urea and urethane, and more particularly, is composed of a main part containing urethane and a curing agent part containing polyaspartate, thereby providing excellent elasticity when coated on leather. And it relates to a composition for leather coating capable of exhibiting durability.

Leather such as natural leather, synthetic leather, and artificial leather is used in the manufacture of furniture, bags, and shoes. It is common for these leather products to be coated using a coating composition to protect the leather. In particular, in the case of sports shoes, there are many relatively expensive products, and there is a problem that a specific part of the leather is easily damaged as a local part of the shoe is repeatedly dragged on the ground due to the nature of the posture of exercise. Therefore, a composition for forming a coating layer having excellent durability on the surface of such a leather product is being developed.

For example, Korean Patent Registration No. 10-1816640 uses a urethane resin composition prepared by optimizing the physical properties of polyether polyol as a coating composition for forming a durable film on the surface of leather. In Nos. 10-2020-0026912 and 10-2020-0026913, etc., it is described that the durability of the coating layer is maintained even when the leather as a base material is bent or bent by using a polyurethane urea dispersion as a composition that can be coated on footwear products. are doing

Looking at this prior art, if a composite composition containing urea and urethane is used, it is expected that a coating layer with improved durability can be formed by having excellent elasticity and abrasion resistance when coating leather.

The present invention has been made in view of the prior art as described above, and an object of the present invention is to provide a composition for leather coating capable of forming a coating layer with excellent durability on the surface of a leather product.

Another object of the present invention is to provide a leather coating composition capable of forming a coating layer having excellent elasticity and wear resistance by using a composite composition containing polyaspartic urea and urethane.

The leather coating composition of the present invention to achieve the above object is characterized by comprising a main part containing a urethane prepolymer, an isocyanate compound, and a silane compound, and a curing agent part containing polyaspartate and aminosilane.

In this case, the urethane prepolymer has an NCO content of 7 to 15%, and the isocyanate compound may be hexamethylene-1,6-diisocyanate trimer (HDT).

In addition, the polyaspartate may have an amine equivalent of 190 to 280 g/eq.

In addition, the leather may be selected from natural leather, synthetic leather, or artificial leather.

Since the composition for leather coating of the present invention can form a coating layer with excellent durability on the surface of a leather product, it has physical properties suitable for coating the surface of leather such as shoes, especially sports shoes, which are easily damaged by the external environment. indicate

In addition, a coating layer having excellent elasticity and wear resistance can be formed by using a composite composition including polyaspartic urea and urethane.

1 is abrasion resistance test results of coating layers to which coating compositions of Examples and Comparative Examples are applied.
Figure 2 is a photograph of the observed state after coating the coating composition of Examples (a) and Comparative Example (b) on the front of baseball shoes.

Hereinafter, the present invention will be described in detail.

The leather coating composition of the present invention is characterized by comprising a main part containing a urethane prepolymer, an isocyanate compound, and a silane compound, and a curing agent part containing polyaspartate and aminosilane.

A general leather coating composition uses a composition containing an aqueous urethane resin, and such a coating composition can easily coat the surface of leather and form a coating layer with excellent abrasion resistance (Korean Patent Registration No. 10-2497978, 10-1565376, etc.). However, when such a conventional coating composition is applied to a leather surface where external impact or repetitive motion on the leather itself occurs, such as shoes, it is difficult to maintain durability for a long time.

In addition, referring to the prior art using a polyurea composition derived from polyaspartic acid as a coating agent (Korean Patent Publication Nos. 10-2021-0002638, 10-2023-0042205, etc.), weather resistance and wear resistance are improved by applying polyurea. , it can be seen that a coating layer having excellent physical properties such as antifouling can be formed.

With reference to these prior art, the present invention provides a coating composition exhibiting improved durability compared to conventional polyurea-based coating agents by applying a combination of polyurethane and polyurea as a coating composition.

The coating composition is a two-component coating agent composed of a main part and a curing agent part, and the coating operation is performed after mixing the main part and the curing agent part before coating the leather surface. The main part and the curing agent part may be mixed in a weight ratio of 0.8: 1 to 1: 0.8, preferably 1: 1, through the reaction of the urethane prepolymer, isocyanate compound and silane compound contained in the main part. Urethane is formed, and polyaspartate contained in the curing agent part is mixed with the main part to form polyaspartic urea, whereby the composition forms a composite coating composition including polyurethane and polyurea do.

The urethane prepolymer constituting the main part is preferably a non-yellowing urethane prepolymer, and may be prepared by reacting a polyol and an isocyanate compound at 80 to 100° C. for 4 hours or more using a catalyst. The urethane prepolymer preferably has an NCO content of 7 to 15%. In addition, it is preferable to use a polyol having a molecular weight of 5,000 to 6,000 g/mol as the polyol for preparing the non-yellowing urethane prepolymer, and as the isocyanate compound, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), It can be used by selecting from hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI).

The urethane prepolymer is preferably contained in the range of 40 to 50% by weight of the total weight of the main part. If the content of the urethane prepolymer is too small, the cost reduction effect is insufficient, and when the coating layer is formed, a problem in that elasticity is lowered, and if the content is too large, tensile strength and mechanical properties are lowered.

In addition, it is preferable to use hexamethylene-1,6-diisocyanate trimer (HDT) as the isocyanate compound. The isocyanate compound is a component used to form polyurea by reacting with polyaspartate when mixed with the curing agent part, and is mixed with the main part and the curing agent part for coating, so that polyurea is formed, thereby forming polyurethane and When forming a composite composition of polyurea, phase separation or deterioration of coating performance is prevented.

The isocyanate compound is preferably contained in the range of 20 to 40% by weight of the total weight of the main part. If the content of the isocyanate compound is too small, it is difficult to form a coating layer with excellent durability and the mechanical properties of the coating layer are also reduced.

In addition, the silane compound is used to improve the hardness of the coating layer, and specifically, it can be prepared by causing a sol-gel reaction between an alkoxysilane and a silane coupling agent in the presence of an acid catalyst in a co-solvent of water and alcohol. Alcohol is removed from the silane compound obtained by the sol-gel reaction by distillation under reduced pressure because, when the alcohol component remains, it reacts with the isocyanate compound. Through the sol-gel reaction, the silane compound undergoes hydrolysis and polycondensation to form a ceramic (SiO ₂ ). As the silane compound is mixed into the composition, the hardness of the coating layer is improved, and the effect of far-infrared emission or antibacterial activity is also improved. You can get it.

The silane compound is contained in the range of 10 to 25% by weight of the total weight of the main part. If the content of the silane compound is too small, sufficient hardness of the coating layer cannot be obtained, and if the content of the silane compound is too large, the elongation of the coating layer may be lowered and cracks may occur. there is.

In addition, a plasticizer may be included in the subject part. As the plasticizer, it is preferable to use a non-phthalate-based plasticizer, and for example, di(2-ethylhexyl) terephthalate may be used. The plasticizer is used to control the viscosity of the main part and increase the stability of the reaction, and may be used in an amount of 1 to 5% by weight based on the total weight of the main part. If the content of the plasticizer is too small, it is difficult to control the viscosity, and if the plasticizer is too large, tensile strength and mechanical properties of the coating layer may be deteriorated.

In addition, the curing agent part mixed with the main part includes polyaspartate and aminosilane, and may additionally contain additives such as pigment, filler (filler), antifoaming agent, leveling agent, dispersant, UV stabilizer, and UV absorber. can

The polyaspartate included in the curing agent part preferably has an amine equivalent of 190 to 280 g/eq. This is in consideration of physical properties suitable for producing polyurea by reaction with an isocyanate compound. Since polyaspartate reacts with an isocyanate compound to form a polyurea coating film, adhesion to leather as a base material, tensile strength, and durability can be improved. However, when the amine equivalent was out of the above range, it was found that physical properties as a coating composition could not be obtained through the polyurethane-polyurea composite composition. Therefore, in order to match the amine equivalent weight, two or more polyaspartates having different molecular weights may be mixed and used.

The polyaspartate is contained in the range of 65 to 80% by weight of the total weight of the curing agent part. If the content of the polyaspartate is too small, sufficient reaction with the isocyanate compound does not occur and the coating film properties cannot be improved. Even if it is too large, the unreacted compound remains and deteriorates the physical properties of the coating layer.

To this end, it is necessary to limit the content of the urethane prepolymer and the isocyanate compound contained in the main part to a specific range. For example, when the content of the urethane prepolymer is out of 40 to 50% by weight, the ratio of polyurethane and polyurea is changed, so that elongation and flexibility cannot be sufficiently secured or durability is deteriorated, and the content of the isocyanate compound It was found that the durability of the coating layer was reduced even when the content of polyaspartate was out of the range of 20 to 40% by weight or 65 to 80% by weight.

In addition, the aminosilane included in the curing agent part promotes the gelation reaction of the unreacted silane compound generated in the main part, thereby improving the hardness and durability of the coating film. In one embodiment, aminotrimethoxy silane may be used as the aminosilane.

The aminosilane is preferably contained in the range of 5 to 10% by weight of the total weight of the curing agent part. This is because if the content of the aminosilane is too small, unreacted silane compounds may remain to deteriorate physical properties of the coating layer, and if the content is too large, unreacted aminosilane compounds may be generated.

In addition, as additives included in the curing agent part, 5 to 10% by weight of a pigment, 1 to 5% by weight of a filler, 0.1 to 0.3% by weight of an antifoaming agent, 0.5 to 3% by weight of a leveling agent, and 0.5 to 3% by weight of a dispersing agent, based on the total weight of the curing agent part. %, 0.5 to 3% by weight of a UV stabilizer and 0.5 to 3% by weight of a UV absorber.

As the filler, any one selected from alumina, silica, mica, zeolite, loess, jade, and titanium dioxide or a mixture thereof may be used, and may be appropriately added according to the physical properties required for the surface of the leather to which the coating composition is applied.

In addition, it is preferable to use a non-silicone-based antifoaming agent as the antifoaming agent, and for example, BYK-011, BYK-012, or BYK-066N may be used. In addition, conventional components such as BYK-333 or BYK-378 as a leveling agent and BYK-182 as a dispersant may be used.

In addition, TINUVIN 292 or Irganox 1010 may be used as a UV stabilizer, and commercially available components such as TINUVIN 1130 may be used as a UV absorber.

The physical properties of the coating layer obtained when the coating composition according to the present invention was applied to leather were confirmed as follows.

The non-yellowing urethane prepolymer constituting the main part is obtained by adding DBTDL as a catalyst to polyether polyol (molecular weight of 5,000 g/mol or more) and isophorone diisocyanate (IPDL) and reacting at 80 to 100 ° C for 4 hours. manufactured.

In addition, in order to prepare a silane compound, 3-aminopropyltrimethoxysilane and a silane coupling agent (Silquest A-171) are mixed with water and ethanol in a volume ratio of 9:1, and 1N hydrochloric acid is added as an acid catalyst to a co-solvent. A sol was obtained by hydrolysis. Silica sol was obtained by distilling the obtained sol under reduced pressure to remove the ethanol component.

Polyether polyol and hexamethylene-1,6-diisocyanate trimer and di(2-ethylhexyl)terephthalate were added to the prepared non-yellowing urethane prepolymer and stirred at room temperature for 1 hour to prepare a main agent.

In order to prepare polyaspartic acid constituting the curing agent part, 3-(2-[2-(3-aminopropoxy)ethoxy]ethoxy)propylamine (3-{2-[2-(3aminopropoxy)ethoxy]ethoxy} propylamine) and diethyl maleate in an equivalent of 1:1 at 60° C. for 10 hours to prepare polyaspartic acid (PAA-1) having an amine equivalent of 197.5 g/mol.

In addition, 2-[2-(2-aminoethoxy)ethoxy]ethylamine (2-[2-(2aminoethoxy)ethoxy]ethylamine) and diethyl maleate were reacted at 60°C for 10 hours at 1:1 equivalent. Polyaspartic acid (PAA-2) having an amine equivalent weight of 227.2 g/mol was prepared.

In addition, 3-[2-(3-aminopropoxy)ethoxy]propylamine (3-[2-(3aminopropoxy)ethoxy]propylamine) and diethyl maleate were reacted at 1:1 equivalent at 60 ° C. for 10 hours Polyaspartic acid (PAA-3) having an amine equivalent weight of 212.8 g/mol was prepared.

Polyaspartic acid was used by mixing PAA-1, PAA-2, and PAA-3 and adjusting the amine equivalent weight to be in the range of 190 to 280 g/eq.

Aminotrimethoxysilane, pearl pigment, mica, antifoaming agent (BYK-011), leveling agent (BYK-333), dispersing agent (BYK-182), UV stabilizer (TINUVIN 292) and UV absorber (TINUVIN 1130) was mixed and stirred at room temperature for 1 hour to prepare a curing agent.

In addition, the main part was prepared by mixing 30% by weight of a urethane prepolymer, 45% by weight of an isocyanate compound, 23% by weight of a silane compound, and 2% by weight of a plasticizer, and the curing agent part consisted of 74% by weight of polyaspartate, 8% by weight of aminosilane, and 6 pearl pigments. It was prepared by mixing 3% by weight of mica, 0.2% by weight of antifoaming agent, 2.4% by weight of leveling agent, 2.4% by weight of dispersant, 2% by weight of UV stabilizer, and 2% by weight of UV absorber. In addition, the main part and the curing agent part were mixed in a weight ratio of 1:1 to form a composition for coating and used for the coating operation.

In addition, for comparison, a coating layer was formed using TUFFTOE, a commercially available baseball shoe coating composition.

Abrasion resistance of the coating layers of Examples and Comparative Examples was evaluated. An appropriate amount of the coating composition of Comparative Examples and Examples was applied to the back of the petri dish with a diameter of 14 cm, and after 7 days, a hole of an appropriate size was drilled in the center of the sample, fixed in a Taber abrasion tester, and then an abrasion resistance test was conducted.

According to the test method of KS F 2813 [Abrasion test method for building materials and building components (abrasive paper method)], the amount of wear is measured by giving 500, 1,000, and 3,000 revolutions at a speed of 60 rpm with a test load of 530 ± 5 g did In addition, the amount of reduction was measured after the first rotation of 500 times using the samples of Comparative Examples and Examples, and then the amount of reduction in wear was measured for a total of 1,000 times by additionally proceeding 500 times. Finally, an additional 2,000 rotations were performed to measure the amount of wear reduction after a total of 3,000 rotations.

As a result of evaluating abrasion resistance, as shown in FIG. 1, the coating layer of Example was evaluated to have improved abrasion resistance because the mass loss rate was less than that of the coating layer of Comparative Example.

In addition, the coating compositions of Examples and Comparative Examples were coated on the surface of commercially available baseball shoes made of natural leather to form a coating layer as shown in FIG. 2, and then the elasticity was compared with the naked eye while pressing the surface. As a result, it was confirmed that the elasticity of the coating layer of the Example was higher than that of the Comparative Example.

From these results, it was found that the coating composition of the present invention can form a coating layer having excellent durability and elasticity when coated on leather.

Although the present invention has been described with preferred embodiments as described above, it is not limited to the above embodiments, and various modifications and modifications can be made by those skilled in the art within the scope of not departing from the spirit of the present invention. Change is possible. Such modifications and variations are to be regarded as falling within the scope of this invention and the appended claims.

Claims (4)

It consists of a main part containing a urethane prepolymer, an isocyanate compound, and a silane compound, and a curing agent part containing polyaspartate and aminosilane,
The urethane prepolymer has an NCO content of 7 to 15%,
The isocyanate compound is hexamethylene-1,6-diisocyanate trimer (HDT),
The silane compound is a composition for leather coating, characterized in that prepared through a sol-gel reaction of an alkoxysilane and a silane coupling agent in the presence of an acid catalyst in a co-solvent of water and alcohol.
delete The method of claim 1,
The polyaspartate is a leather coating composition, characterized in that the amine equivalent weight is 190 to 280 g / eq.
The method of claim 1,
The leather is a composition for coating leather, characterized in that natural leather, synthetic leather or artificial leather.

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