CN103882726B - One prepares the method for synthetic leather dry process PU/PVDF hydrophobic polyurethane coating - Google Patents

Abstract

A method for preparing a dry-process PU/PVDF hydrophobic polyurethane coating for synthetic leather, comprising the following steps: 1) first mixing polyurethane PU and polyvinylidene fluoride PVDF; 2) adding nitrogen nitrogen dimethyl formamide DMF: acetone MEK=0～50: 0～20 parts by mass of organic solvent, then add color paste auxiliary materials to configure the surface layer; according to PU:DMF:MEK: color paste=0～100:0～50:0～ The ratio of 20:0～15 is configured as an adhesive layer, and the surface layer slurry and the adhesive layer fabric are fully stirred with a vacuum mixer at room temperature to form a viscosity solution slurry; 3) Apply the dry surface layer coating on the release type The PU/PVDF dry-process surface layer is obtained after curing and molding on the paper; the adhesive layer is coated on the surface layer, and the synthetic leather wet-process substrate is laminated with the dry-process surface layer by a semi-dry pasting method, and the present invention is obtained after drying and aging. Product: After PU/PVDF blending and modification, the coating has high hydrophobicity, anti-pollution, flame retardant coefficient, high mechanical tensile strength, simple method, low requirements, low cost, and is easy to apply in the industrial production of synthetic leather.

Description

A kind of method for preparing synthetic leather dry process PU/PVDF hydrophobic polyurethane coating

technical field

The invention belongs to the technical field of hydrophobic modification of a polyurethane coating for synthetic leather, and in particular relates to a method for preparing a dry-process PU/PVDF hydrophobic polyurethane coating for synthetic leather.

Background technique

Hydrophobic polyurethane coating is a kind of polyurethane material with special properties, which is widely used in the coating field because of its special properties. Hydrophobic polyurethane coating has always been used as a special material in the application field of synthetic leather. Its effective hydrophobic function within a certain range can make synthetic leather materials more comfortable and suitable for human use. Without changing the existing hygienic performance, the hydrophobic performance becomes particularly important, and it is widely used in special garment leather, shoe leather, building material outsourcing coating and other fields. At present, the application research on the hydrophobic modification of polyurethane mainly uses the modification of nano-silica inorganic materials, and the silicon dioxide is modified by vinyl-based siloxane coupling agents to obtain materials with hydrophobic functions. The complex preparation process of this method is not conducive to rapid industrial application. With the development of polyurethane materials, hydrophobic polyurethane coatings will be widely used in the fields of architectural coatings, special materials, substrate coatings and paint coatings due to their special properties.

PVDF has excellent corrosion resistance, except for a few polar solvents (DMF, acetone, methyl ethyl ketone, etc.), fuming sulfuric acid, fuming nitric acid, chlorosulfonic acid, high temperature concentrated alkali, it can resist most inorganic acids and alkalis Corrosion of salts, organic acids, organic solvents, halogen compounds, and aromatic hydrocarbons. PVDF has excellent hydrophobicity, anti-pollution and weather resistance. Its film products have been exposed to sunlight and wind and rain for 3000 hours outdoors, and the tensile strength has not changed significantly. It has been used in a chemical atmosphere for one year, and its mechanical properties have not declined. For large high-rise buildings , coated with PVDF outer layer, can withstand 30 years of ultraviolet radiation and wind and rain erosion, still no pollution, no brittle cracks, no aging, this is the anti-pollution, hydrophobicity and weather resistance that any other fluoroplastics do not have.

At present, synthetic leather for ordinary shoes, synthetic leather for sofas, and synthetic leather for car seat cushions mostly use ordinary resins for the surface layer of polyurethane. Although they have a certain hydrophobic function, their hydrophobic performance and anti-pollution performance are relatively poor. At present, the market mainly relies on silica fillers and hydrophobic additives for treatment in order to achieve the purpose of hydrophobic and anti-pollution, but this method is expensive in industrialization, which is not conducive to industrial production and the improvement of economic benefits.

Contents of the invention

In order to overcome above-mentioned deficiencies in the prior art, the object of the present invention is to provide a kind of method for preparing synthetic leather with dry method PU/PVDF hydrophobic polyurethane coating, and this method has simple and easy operation, is easy to industrialized application, and raw material is cheap and easy to obtain features.

In order to achieve the above object, the technical solution adopted in the present invention is a method for preparing synthetic leather with dry process PU/PVDF hydrophobic polyurethane coating, comprising the following steps:

1) First mix polyurethane PU and polyvinylidene fluoride PVDF according to the mass fraction ratio of 100:5, 100:10 or 100:15;

2) Add nitrogen nitrogen dimethylformamide DMF: acetone MEK=0～50:0～20 parts by mass of solvent, the solvent includes dimethylformamide DMF and acetone MEK, disperse the two in the organic solvent, and then Add 0-15 parts by mass of color paste auxiliary and auxiliary materials to configure the surface layer slurry; also according to polyurethane PU: nitrogen nitrogen dimethyl formamide DMF: acetone MEK: color paste = 0 ~ 100: 0 ~ The ratio of 50:0～20:0～15 is configured as the adhesive layer, and the surface layer slurry and the adhesive layer fabric are fully stirred for 2 hours at room temperature with a vacuum mixer to form a surface layer slurry with a viscosity of , the viscosity of the adhesive layer fabric is The solution slurry; Utilize the vacuum machine to evacuate and defoam the modified solution for 2h, then let it stand for defoaming for 12h;

3) By spraying or scraping, apply it on the release paper and cure to obtain a polyurethane coating with hydrophobic and flame-retardant functions. This polyurethane coating is mainly used in the dry process of synthetic leather production. Film transfer process.

The beneficial effects of the present invention are:

The polyurethane coating is mainly used in the dry film transfer process in the production process of synthetic leather. After PU/PVDF blend modification, the hydrophobicity, anti-pollution and flame retardant coefficient of the coating are improved, and the mechanical tensile strength of the dry coating is also improved. When PU:PVDF=100:15 The tensile strength of the dry coating is increased from 0.142MPa to 0.150MPa. The preparation method is simple, has low requirement conditions, low cost and is easy to apply in the industrial production of synthetic leather. In addition, polyvinylidene fluoride PVDF has the characteristics of both general-purpose resins and fluororesins. In addition to good high temperature resistance, chemical corrosion resistance, oxidation resistance, radiation resistance, and weather resistance, it also has good piezoelectricity, Dielectric, pyroelectric and other special properties. The dry-process PU/PVDF hydrophobic polyurethane coating for synthetic leather of the present invention has very large economic value.

The addition of polyvinylidene fluoride PVDF filler additives is very convenient, and it is directly mixed with polyurethane PU according to the proportion in the early stage of batching to make surface layer slurry. Moreover, the price of industrial PVDF is cheap, and the hydrophobic polyurethane synthetic leather has a great application prospect in the market. Therefore, the dry-process PU/PVDF hydrophobic polyurethane coating for synthetic leather has great economical value.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments. We take the manufacturing process of synthetic leather for ordinary shoes as an implementation case.

(1) Resin raw material

(2) Process plan

Surface layer: HDS-50HF, adhesive layer: HDA-20; surface layer slurry coating thickness 0.10mm, adhesive layer slurry coating thickness 0.10mm; release paper AW-67; base material 0.8mm ordinary wet shoes Semi-finished leather products; bonding method: semi-dry bonding; gap between pressure rollers 0.5mm; that is, peeling off

(3) Process formula

Embodiment one

A method for preparing synthetic leather with dry process PU/PVDF hydrophobic polyurethane coating, comprises the following steps:

1) First mix HDS-50HF polyurethane PU and polyvinylidene fluoride PVDF according to the mass fraction ratio of 100:5;

2) Add nitrogen nitrogen dimethylformamide DMF: acetone MEK = 40:20 mass parts solvent, the solvent includes dimethyl formamide DMF and acetone MEK, disperse the two in the organic solvent, and then add mass parts It is 15 parts of color paste auxiliary materials, configured as a surface layer; also configured according to the ratio of HDA-20 polyurethane PU: nitrogen nitrogen dimethyl formamide DMF: acetone MEK: color paste = 100:20:20:15 For the adhesive layer, the surface layer slurry and the adhesive layer fabric were fully stirred with a vacuum mixer at room temperature for 2 hours, so that their viscosities were respectively at , using a vacuum machine to vacuumize the modified solution for degassing for 2 hours, and then let it stand for degassing for 12 hours;

3) Spray the surface layer solution on the release paper with a coating thickness of 0.1mm and dry it in an oven at 120°C for 10 minutes; take out the release paper and scrape the adhesive layer slurry with a thickness of 0.1mm; then put it in the oven Dry for 4 minutes; take out the 0.8mm ordinary wet-laid leather semi-finished product and paste it; put it in an oven to dry for 10 minutes; take it out and let it stand at room temperature and peel it off to obtain a synthetic leather with a hydrophobic polyurethane coating. The surface layer of the hydrophobic synthetic leather is in contact with Compare to 67°.

Embodiment two

A method for preparing synthetic leather with dry process PU/PVDF hydrophobic polyurethane coating, comprises the following steps:

1) First mix HDS-50HF polyurethane PU resin and polyvinylidene fluoride PVDF according to the mass fraction ratio of 100:10;

2) Add nitrogen nitrogen dimethylformamide DMF: acetone MEK=40:20 solvent in parts by mass, the solvent includes dimethylformamide DMF and acetone MEK, disperse the two in the organic solvent, and then add mass parts 15 parts of color paste and other auxiliary auxiliary materials are configured as a surface layer; also configured as a bonding agent according to the ratio of polyurethane PU: nitrogen nitrogen dimethyl formamide DMF: acetone MEK: color paste = 100:20:20:15 layer, the surface layer slurry and the adhesive layer fabric were fully stirred at room temperature with a vacuum mixer for 2 hours, so that their viscosities were respectively at , using a vacuum machine to vacuumize the modified solution for degassing for 2 hours, and then let it stand for degassing for 12 hours;

3) Spray or scrape the surface layer solution on the release paper with a coating thickness of 0.1mm and dry it in an oven at 120°C for 10 minutes; take out the release paper and scrape the adhesive layer slurry with a thickness of 0.1mm; Put it in an oven to dry for 4 minutes; take it out and attach it to a 0.8mm ordinary wet-laid leather semi-finished product; put it in an oven and dry it for 10 minutes; take it out and let it cool down to room temperature and peel it off to obtain a synthetic leather with a hydrophobic polyurethane coating. The contact angle of the surface layer of the hydrophobic synthetic leather is 72°.

Embodiment three

A method for preparing synthetic leather with dry process PU/PVDF hydrophobic polyurethane coating, comprises the following steps:

1) First, mix HDS-50HF polyurethane PU and polyvinylidene fluoride PVDF according to the mass fraction ratio of 100:15. When the ratio of PU to PVDF exceeds 100:15, the film will become hard and brittle, which is not conducive to synthetic leather. ;

2) Add nitrogen nitrogen dimethylformamide DMF: acetone MEK = 40:20 mass parts solvent, the solvent includes dimethyl formamide DMF and acetone MEK, disperse the two in the organic solvent, and then add mass parts It is 15 parts of color paste and other auxiliary materials, configured as a surface layer; also configured according to the ratio of HDA-20 polyurethane PU: nitrogen nitrogen dimethyl formamide DMF: acetone MEK: color paste = 100:20:20:15 To form a cohesive layer, the surface layer slurry and the cohesive layer fabric were fully stirred with a vacuum mixer at room temperature for 2 hours, so that their viscosities were respectively , using a vacuum machine to vacuumize the modified solution for degassing for 2 hours, and then let it stand for degassing for 12 hours;

3) Squeegee-coat the surface layer solution on the release paper with a coating thickness of 0.1mm and dry it in an oven at 120°C for 10 minutes; take out the release paper and squeegee-coat the adhesive layer slurry with a thickness of 0.1mm; then put it in Dry in the oven for 4 minutes; take it out and attach the 0.8mm ordinary wet-laid leather semi-finished product to it; put it in the oven to dry for 10 minutes; take it out and let it cool down to room temperature and peel it off to obtain a synthetic leather with a hydrophobic polyurethane coating. The contact angle of the synthetic leather surface layer was 81°.

The hydrophobicity of the polyurethane coating for synthetic leather modified with PVDF has been greatly improved. Through the measurement of its contact angle, we can find that the contact angle of the dry surface layer without adding PVDF modification is 42°, after adding 5/10/15 parts of PVDF modification, the contact angle of the dry surface layer increased to 67°, 72°, 81° respectively. It fully demonstrates that the polyurethane dry-process surface layer for synthetic leather modified with PVDF has a certain degree of hydrophobicity, and the anti-pollution ability has been greatly improved. By testing the flame retardant properties of the modified polyurethane coating, we found that its flame retardant properties have also been improved to a certain extent. Through the test of the tensile strength of the modified polyurethane dry-process surface layer, its tensile strength has also been greatly improved. This fully demonstrates that the dry-process film-forming polyurethane coating modified with PVDF not only improves the hydrophobicity to a great extent, but also improves its flame retardant properties and tensile strength, and will not affect the surface layer of the polyurethane. other properties. These characteristics will make this modification method more widely used in the fields of polyurethane coatings, coatings and cladding materials in the future.

Claims (4)

1. prepare a method for synthetic leather dry process PU/PVDF hydrophobic polyurethane coating, it is characterized in that, include following steps:

1) first polyurethane PU and Kynoar PVDF are mixed than for the ratio of 100:5,100:10 or 100:15 according to mass fraction;

2) dimethyl formamide DMF is added: the solvent of acetone MEK=0 ~ 50:0 ~ 20 mass fraction, solvent comprises dimethyl formamide DMF and acetone MEK, make the two be scattered in organic solvent, then add the mill base auxiliary addition agent material that mass fraction is 0 ~ 15 part, be configured to surface layer slurry; Same according to polyurethane PU: dimethyl formamide DMF: acetone MEK: the proportional arrangement of mill base=0 ~ 100:0 ~ 50:0 ~ 20:0 ~ 15 becomes gluing layer, surface layer slurry, gluing layer slurry are fully at room temperature stirred 2h with de-airing mixer respectively, to be formed surface layer slurry viscosity be 3000 ~ 5000mPas, gluing layer slurry viscosity is the solution slurry of 6000 ~ 15000mPas; Utilize evacuator to modified solution vacuumizing and defoaming 2h, then standing and defoaming 12h;

In described solvent, each component does not comprise 0 number; Described mill base auxiliary addition agent material does not comprise 0 number; The polyurethane PU that described gluing layer comprises, dimethyl formamide DMF, acetone MEK and mill base all do not comprise 0 number;

3) adopt spraying or the method for blade coating, coated and release liners obtains a kind of there is hydrophobic and polyurethane coating that is anti-flaming function after solidification.

2. one according to claim 1 prepares the method for synthetic leather dry process PU/PVDF hydrophobic polyurethane coating, it is characterized in that, includes following steps:

1) first mix than the ratio for 100:5 according to mass fraction with Kynoar PVDF by polyurethane PU;

2) and then add dimethyl formamide DMF: the solvent of acetone MEK=40:20 mass fraction, solvent comprises dimethyl formamide DMF and acetone MEK, make the two be scattered in organic solvent, then add the mill base auxiliary addition agent material that mass fraction is 15 parts, be configured to surface layer; According to polyurethane PU: dimethyl formamide DMF: acetone MEK: the proportional arrangement of mill base=100:20:20:15 becomes gluing layer, surface layer slurry, gluing layer slurry are fully at room temperature stirred 2h with de-airing mixer respectively, make its viscosity respectively at 4000mPas, 8000mPas, utilize evacuator to modified solution vacuumizing and defoaming 2h, then standing and defoaming 12h.

3) be sprayed in release liners by surface layer polyurethane slurry, coating thickness is 0.1mm dry 10min at 120 DEG C in an oven; Take out release liners, the gluing layer slurry of blade coating 0.1mm thickness; Put it into oven drying 4min again; Take out 0.8mm normal wet leather semi-finished product and its laminating; Put into oven drying 10min; Take out to leave standstill and be down to room temperature stripping, namely obtain the synthetic leather of modification PU-PVDF hydrophobic polyurethane coating.

3. one according to claim 1 prepares the method for synthetic leather dry process PU/PVDF hydrophobic polyurethane coating, it is characterized in that, includes following steps:

1) first polyurethane PU resin is mixed than the ratio for 100:10 according to mass fraction with Kynoar PVDF;

2) and then add dimethyl formamide DMF: the solvent of acetone MEK=40:20 mass fraction, solvent comprises dimethyl formamide DMF and acetone MEK, make the two be scattered in organic solvent, then add the mill base auxiliary addition agent material that mass fraction is 15 parts, be configured to surface layer; According to polyurethane PU: dimethyl formamide DMF: acetone MEK: the proportional arrangement of mill base=100:20:20:15 becomes gluing layer, surface layer slurry, gluing layer slurry are fully at room temperature stirred 2h with de-airing mixer respectively, make its viscosity respectively at 3000mPas, 6000mPas, utilize evacuator to modified solution vacuumizing and defoaming 2h, then standing and defoaming 12h;

3) be sprayed in release liners by surface layer polyurethane slurry, coating thickness is 0.1mm dry 10min at 120 DEG C in an oven; Take out release liners, the gluing layer slurry of blade coating 0.1mm thickness; Put it into oven drying 4min again; Take out 0.8mm normal wet leather semi-finished product and its laminating; Put into oven drying 10min; Take out to leave standstill and be down to room temperature stripping, obtain the synthetic leather of modification PU/PVDF hydrophobic polyurethane coating.

4. one according to claim 1 prepares the method for synthetic leather dry process PU/PVDF hydrophobic polyurethane coating, it is characterized in that, includes following steps:

1) first polyurethane PU and Kynoar PVDF are mixed than for the ratio of 100:15 according to mass fraction;

2) and then add dimethyl formamide DMF: the solvent of acetone MEK=40:20 mass fraction, solvent comprises dimethyl formamide DMF and acetone MEK, make the two be scattered in organic solvent, then add the mill base auxiliary addition agent material that mass fraction is 15 parts, be configured to surface layer; According to polyurethane PU: dimethyl formamide DMF: acetone MEK: the proportional arrangement of mill base=100:20:20:15 becomes gluing layer, surface layer slurry, gluing layer slurry are fully at room temperature stirred 2h with de-airing mixer respectively, its viscosity is made to be respectively 5000mPas, 15000mPas, utilize evacuator to modified solution vacuumizing and defoaming 2h, then standing and defoaming 12h;

3) be sprayed in release liners by surface layer polyurethane slurry, coating thickness is 0.1mm dry 10min at 120 DEG C in an oven; Take out release liners, the gluing layer slurry of blade coating 0.1mm thickness; Put it into oven drying 4min again; Take out 0.8mm normal wet leather semi-finished product and its laminating; Put into oven drying 10min; Take out to leave standstill and be down to room temperature stripping, namely obtain the synthetic leather of modification PU/PVDF hydrophobic polyurethane coating.