KR20170105750A - coating composition for natural leather - Google Patents

Abstract

The present invention relates to an eco-friendly coating composition for coating natural leather. More specifically, provided is an eco-friendly coating composition for coating natural leather with enhanced low temperature bending properties without deteriorating physical properties of produced films such as wear resistance, flexibility, low temperature bending properties, or color changes. To this end, the composition for coating natural leather contains nitrocellulose and isosorbide alkyl ester at the weight ratio of 90-99 : 10-1. The coating composition is used for natural leather, and contains isosorbide alkyl ester.

Description

Coating composition for natural leather "

The present invention relates to a coating composition for natural leather, and more particularly to an environmentally friendly coating composition for coatings for natural leather comprising an environmentally friendly isosorbide alkyl ester without impairing the physical properties of the film to be formed.

Natural leather products are coated with resins such as nitrocellulose, PVC, and polyurethane to improve abrasion resistance and gloss. Plasticizers are mixed to improve the physical properties and processability of these resins.

Currently, the most widely used coating composition is a plasticizer containing phthalate-based DOP (Dioctyl Phthalate), which accounts for more than 70%.

However, phthalate plasticizers not only damage the liver and kidneys, but also cause endocrine disruption as a kind of endocrine hormones. Therefore, REACH in Europe and CPSIA in the United States are designated as regulated substances. This is because the plasticizer is gradually discharged out after coating formation.

Thus, various environmentally friendly plasticizers such as glycerol ester and isosorbide alkyl ester have been developed. The following are inventions relating to environmentally friendly plasticizers and coating compositions containing them.

Korean Patent Laid-Open Publication No. 10-2013-0114344 discloses a biodegradable resin composition containing an environmentally friendly plasticizer and a biodegradable resin product using the biodegradable resin composition. The biodegradable resin composition of the present invention comprises a biodegradable resin and a plasticizer, and a benzoate plasticizer is used as the plasticizer. The biodegradable resin composition of the present invention improves the low plasticizability of the citrate plasticizer and is excellent in high temperature moldability.

Korean Patent Laid-Open Publication No. 10-2013-0059493 discloses an environmentally friendly plasticizer made from vegetable oils such as soybean oil, palm oil, and flax oil, and a coating composition containing the same. The coating composition of the present invention is harmless to the human body while having a physical property equal to or higher than that of the coating composition containing the phthalate plasticizer.

Korean Patent Laid-Open Publication No. 10-2012-0102551 discloses a nano-brush type environmentally friendly plasticizer compound. The nano-brush type environmentally friendly plasticizer of the present invention is a compound that ring-polymerizes a lactone monomer having environmental compatibility and biocompatibility with a core material harmless to the environment and human body as a brush material, and finally stabilizes the terminal hydroxyl group of the brush. The coating composition containing the plasticizer of the present invention is excellent in compatibility with polyvinyl chloride (PVC), and the plasticizer does not flow out of the PVC.

International Patent Publication No. WO 2011/141408 discloses a thermoplastic polyurethane coating composition comprising glycerol esterified by at least one aliphatic carboxylic acid as plasticizer.

International Patent Application WO 2010/111007 discloses plastisols and organosol coating compositions comprising monoesters, diesters and triesters of glycerol as plasticizers. The plasticizers are good solvating agents for PVC and impart low viscosity to plastisols and organosols.

WO 2010/107583 discloses aqueous polymer dispersions comprising monoesters, diesters and triesters of glycerol as plasticizers. The aqueous polymer dispersions of the present invention have good film forming properties and are useful as aqueous coatings, sealants, adhesives, brighteners, films and inks, and the plasticizer of the present invention is a copolymer of polyvinyl acetate, vinyl acetate and ethylene or other olefins , An acrylic polymer, an acrylic / styrene copolymer, a polyester, a polyurethane, an elastomeric styrene / butadiene copolymer and neoprene, and is also compatible with another plasticizer.

However, coating compositions containing environmentally friendly plasticizers are disadvantageous in that they change in hue, low temperature flexibility, flexibility or abrasion resistance.

Typically, in the leather industry, coating properties include film adhesion, film smoothness, abrasion resistance, flexibility, clarity of color, low-temperature bending properties, and the like, in order to hide mistakes in previous processes or increase durability against scratches.

Nitrocellulose (NC), which is used to coat leather, is soluble in almost all solvents and forms a clear, hard, durable film that is insoluble in water after drying. Since nitrocellulose alone forms a very strong and well-breaking film, 5 to 10% of a plasticizer is added to the film.

It is an object of the present invention to provide an environmentally friendly coating composition for natural leather coating which is improved in low temperature flexibility without deteriorating the physical properties of the formed film such as hue, low temperature flexibility, flexibility or abrasion resistance.

The coating composition for natural leather for solving the above-mentioned problems is characterized in that the weight ratio of nitrocellulose: isosorbide alkyl esters is 90 to 99: 10-1.

The coating composition of the present invention is intended for natural leather and has constitutional features in that it contains isosorbide alkyl esters.

The isosorbide alkyl ester used in the present invention is prepared by reacting isosorbide with a fatty acid, and is characterized in that a phosphorus based catalyst selected from POCl ₃ , PCl ₃ and PCl ₅ is used as a catalyst.

The fatty acid is preferably an alkyl fatty acid having 5 to 10 carbon atoms, and toluene, isosorbide dimethyl ether or isosorbide diethyl ether is used as the solvent.

The solvent may use an additional alkylamine. In addition to acting as a solvent, the alkylamine also absorbs the hydrogen chloride generated during the reaction to prevent smell.

According to the present invention, there is provided a coating composition for natural leather which can replace DOP known as an environmental hormone without impairing the physical properties of the coating composition such as low temperature flexibility, gloss, abrasion resistance and flexibility.

Examples 1 and 2 below are production examples of an isosorbide alkyl ester used as a plasticizer in the composition for coating natural leather of the present invention.

≪ Example 1 >

146.14 g of isosorbide and 144.21 g of n-octanoic acid were charged in 677.5 g of toluene, and the temperature was raised to 30 캜 while stirring. Subsequently, 101.19 g of triethylamine was slowly added thereto, and 153.33 g of POCl ₃ was added thereto over a period of 1 hour while maintaining the temperature at 30 ° C, the temperature was raised to 60 ° C and the mixture was stirred for 30 minutes.

The temperature was lowered to room temperature, and the resulting salt was filtered to obtain 260 g of isosorbide alkyl ester. This is a pale yellow transparent liquid. The solids content is 98.5%, and the BROOKFIELD viscosity measured at 15.5 ° C and 50 rpm is 67.4. Hereinafter, this is referred to as " plasticizer I ".

≪ Example 2 >

146.14 g of isosorbide and 144.21 g of n-octanoic acid were added to 677.5 g of isosorbide diethyl ether and the temperature was raised to 30 캜 while stirring. Subsequently, 101.19 g of triethylamine was slowly added thereto, and 153.33 g of PCl ₃ was added thereto over 2 hours while the temperature was maintained at 30 ° C. The temperature was raised to 60 ° C and the mixture was stirred for 30 minutes.

The temperature was lowered to room temperature, and the resulting salt was filtered to obtain 260 g of isosorbide alkyl ester. This is a pale yellow transparent liquid phase. The solids content is 96.6%, and the BROOKFIELD viscosity measured at 15.5 ° C and 50 rpm is 66.0. Hereinafter, this is referred to as plasticizer II.

The physical properties (solid content, viscosity) of the conventional plasticizers DOA and glycerol, and the isosorbide alkyl ester prepared in Examples 1 and 2 of the present invention are as follows.

The results of measuring the solid content and viscosity of the plasticizer prepared in Examples 1 and 2 and the conventional plasticizer are as follows.

Except for glycerol, the solid content was 96 to 99%, and the viscosity was higher than that of DOA, and the plasticizers prepared in Examples 1 and 2 were higher than those of DOA, which is suitable as a plasticizer for natural leather. The appearance of the plasticizer prepared in Examples 1 and 2 is a yellow transparent liquid state, and the DOA is colorless and transparent. Among the conventional plasticizers, glycerol has a low solids content, which is considered to be difficult to use for leather coating.

≪ Example 3 >

As shown in Table 2, the coating composition was prepared by changing the content of the plasticizers DOP as the conventional plasticizer and the plasticizers of Examples 1 and 2, coating the natural leather and measuring physical properties such as low temperature bending resistance, abrasion resistance and flexibility of the coated natural leather Respectively.

The lacquer was prepared by mixing 1: 4 nitrocellulose (NC): solvent, and the leather was a Pakistani sheepskirt.

Table 3 shows the physical properties when the conventional plasticizer DOP was used as the plasticizer, and physical properties when the plasticizer prepared in Examples 1 and 2 were used as the plasticizer are shown in Table 4 and Table 5, respectively.

When the content of plasticizer was less than 7%, the% loss was 0.09 ~ 0.45 (%) when nitrocellulose (NC) was diluted with cyclohexane as a solvent and the DOA content was changed to 1 ~ 10% %, And the result of the gloss of 1.7 ~ 2.3 was obtained. In addition, as a result of the flexibility test according to KS M ISO 17235, a flexible coated leather having a thickness of 6.5 mm or more could be produced, and the cracking phenomenon of the film layer could not be confirmed as a result of the low temperature bending test conducted at -10 ° C. Using the DOA content of 1 ~ 5% in the existing natural leather process, similar results were obtained.

When the content of the plasticizer prepared in Example 1 was changed to 1 to 10% after coating with nitrocellulose (NC) diluted with cyclohexane as a solvent, when the plasticizer content was 5 to 7% The cracking phenomenon of the film layer was confirmed as a result of the low temperature bending property test at 10 ℃ and the loss of abrasion loss (% loss) was confirmed to be 0.7 ~ 1.4%. In the case of gloss, the results of 1.5 ~ 3.3 were obtained. In addition, the flexible test according to KS M ISO 17235 has resulted in the production of flexible coated leather of 6.5 mm or more.

After diluting nitrocellulose (NC) with cyclohexane as a solvent, coating experiment was conducted under the condition that the content of plasticizer prepared in Example 1 was changed to 1 to 10%. As a result, when the plasticizer content was 7% or less, % loss) was 0.5 ~ 0.7% and the gloss was 2.8 ~ 3.5, which was higher than that of conventional plasticizer. In addition, as a result of the flexibility test according to KS M ISO 17235, a flexible coated leather having a thickness of 6.5 mm or more could be produced, and the cracking phenomenon of the film layer could not be confirmed as a result of the low temperature bending test conducted at -10 ° C. In the case of the plasticizer II, properties similar to those of conventional plasticizers were confirmed, and the possible results were confirmed on the field of natural leather.

As a result, it can be confirmed that the isosorbide alkyl ester is superior to DOP, which is a conventional plasticizer, and is particularly excellent in low-temperature flexibilty when it is used as a plasticizer for natural leather.

Claims (5)

Wherein the weight ratio of nitrocellulose: isosorbide alkyl ester is from 90 to 99: 10 to 1. The process for producing isosorbide alkyl ester according to claim 1, wherein a phosphorus-based catalyst selected from POCl ₃ , PCl ₃ and PCl ₅ is used as a catalyst in the production of isosorbide alkyl ester by reacting isosorbide with fatty acid ≪ / RTI > The coating composition for natural leather according to claim 2, wherein the fatty acid is an alkyl fatty acid having 5 to 10 carbon atoms. The coating composition for natural leather according to claim 2, wherein one or more selected from among toluene, isosorbide dimethyl ether and isosorbide diethyl ether is used. The coating composition for natural leather according to claim 4, wherein an alkylamine is further used as a solvent.