JPS6235516B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to bags such as bags and handbags, footwear such as shoes and sandals, clothing such as jackets and suits, chair upholstery and seat covers, etc. (hereinafter referred to as personal items). This invention relates to synthetic leather used as a surface material. The surface materials of these personal items are constantly subjected to expansion/contraction stress, bending stress, or frictional stress during use. Therefore, the synthetic leather used for it must first of all have the elasticity, flexibility, abrasion resistance, and
It must have excellent physical properties such as crack resistance. Second, since these personal items are used in constant contact with the skin, the synthetic leather that serves as the surface material must be flexible, have low thermal conductivity, and be warm to the touch. or,
Thirdly, since these personal items are also decorative items, their surfaces must have a smooth and clean appearance without any unsightly cracks or irregularities. The reason why synthetic leather is used in place of natural leather is that it is industrially mass-produced at low cost, has excellent physical properties, texture, and processability, and is particularly good in water resistance, which natural leather lacks. This can be said to be because the characteristics of productivity and physical quality of natural leather have a practical effect that exceeds the rarity value and unique texture of natural leather. Therefore, synthetic leather used as a surface material for bags and other personal items is superior to natural leather in productivity and physical quality, closely resembles natural leather in texture, and has a beautiful surface appearance. There shall be no irregularities or other flaws that may impair the quality of the product. The present invention is utilized for producing synthetic leather that satisfies these quality characteristics. [Prior Art] Conventionally, synthetic leather used for personal items such as bags, etc.
It is made by coating a base material with a resin solution prepared by blending a base resin with a stabilizer, wetting agent, filler, foaming agent, etc., and then laminating a thin film. Normally, to form a porous and lightweight resin film,
The resin solution used as the material is mechanically foamed with a mixer, or a foaming agent is added and foamed by heating.
Alternatively, a method may be used in which foaming is performed using a reaction product gas of the resin terminal group without adding a foaming agent. However, with this foaming method, it is difficult to adjust the gelation rate of the resin solution and the foaming speed, and the bubbles become uneven. It is not suitable for manufacturing. Therefore, in order to make a polyurethane elastomer resin film porous and lightweight, it is necessary to prepare the polyurethane elastomer resin as a resin solution containing dimethylformamide, apply it to the base material, and then form the polyurethane elastomer resin film. Alternatively, a so-called wet method is used in which the film or coating is immersed in warm water to extract dimethylformamide immediately after applying the polyurethane elastomer resin solution to the base material. [Problems to be solved by the invention] According to such a wet method, the production process is stable and the porous bubbles are fine and uniform, but this requires an extraction process using hot water and a hot water washing process. Therefore, the production equipment must be enlarged, and since dimethylformamide is a hazardous substance, a device to recover it after extraction is required, resulting in equipment investment that poses problems in terms of pollution and occupational health. Furthermore, since dimethylformamide, which is finely dispersed inside the resin film together with the polyurethane elastomer resin, is to be extracted, the extraction process takes a long time, which poses a problem in terms of productivity. In order to solve this problem, as disclosed in Japanese Patent Publication No. 48-31881, dimethylformamide is absorbed and supported inside the porous powder, thereby preventing the dimethylformamide from being finely dispersed inside the film and making it easier to extract. I also thought of a way to say it. However, polyurethane elastomer resin films containing porous powder lack elasticity and are prone to cracking, and the synthetic leather made therefrom is not suitable for personal items such as bags. In particular, in Japanese Patent Publication No. 48-31881, after extracting dimethylformamide, the absorbed water is squeezed out instead, so the porous powder mixed therein has to be coarse with large pores. The polyurethane elastomer resin film also has to be thick, making it impossible to obtain extremely thin and flexible synthetic leather with a film thickness of 100 to 200 μm. Therefore, even though Japanese Patent Publication No. 48-31881 can be applied to thick fabrics such as raised fabrics and needle-punched felt non-woven fabrics, in which a polyurethane elastomer resin solution is soaked into the inside of the fabric for reinforcement,
The object of the invention is thereby not achieved. [Object of the Invention] That is, the first object of the present invention is to provide a synthetic leather that is superior to natural leather in productivity and physical quality, closely resembles natural leather in texture, and is suitable as a surface material for personal items such as bags. The goal is to manufacture it economically. A second object of the present invention is to form the skin of synthetic leather with an ultra-thin film that is porous, lightweight, and has low thermal conductivity in order to achieve the first object. The objective is to ensure that the physical properties required for practical use, such as flexibility, abrasion resistance, and crack resistance, which are required of leather, are not impaired. [Structure of the Invention] The method for producing synthetic leather according to the present invention achieves the above-mentioned purpose, and contains inorganic silicate as a main component,
Average particle size is 60~80μ, particle size variation range is 10~
300μ, the thickness of the sphere wall surrounding the hollow part is 0.5~5μ
A polyurethane elastomer resin solution in which hollow fine spheres have a solid content of 50% by weight or less is coated on a base material, laminated, and heat treated to form a surface film of synthetic leather made of polyurethane elastomer resin. It is. That is, the present invention provides (1) that the inorganic silicate exhibits extremely excellent compatibility with the polyurethane elastomer resin, and (2) that the inorganic silicate has an average particle size of 60 to 80 μ and a variation in particle size (distribution). A hollow sphere with a diameter in the range of 10 to 300μ and a sphere wall thickness of 0.5 to 50μ is mixed with a polyurethane elastomer resin solution and applied to a substrate so that it accounts for 50% by weight or less of the solid content in the solution. (3) The hollow spheres retain their shape without breaking or deforming during the heating process to solidify the polyurethane elastomer resin. (4) Even if the adjacent hollow spheres make point contact inside the formed film, they do not become entangled, and therefore, the polyurethane elastomer resin deforms due to external stress. (5) Inorganic silicates provide flexibility, elasticity, crack resistance, and abrasion resistance to the entire film by sliding between the hollow spheres and thereby relieving the applied external stress. (6) The porous structure composed of hollow spheres impedes thermal conductivity, so the polyurethane elastomer resin film has a moderate tactile feel that closely resembles natural leather. It was completed based on the knowledge that the Therefore, if the hollow spheres mainly composed of inorganic silicates have a particle size of 10 μm or less, they will not have a porous structure that gives a sense of warmth; on the other hand, if the particle size is 300 μm or less,
In the above cases, a smooth, ultra-thin and flexible film cannot be produced, and if the spherical wall is too thin, it will break easily, and on the other hand, if it is too thick, the film will have high thermal conductivity and will feel cold to the touch. cause inconvenience. In particular, if the inorganic silicate has a fine porous structure with broken pores and an angular surface, the particles of the inorganic silicate will not make point contact with each other and will interlock like stone walls. The coating becomes rough and hard and easily cracks. Therefore, the inorganic silicate used together with the polyurethane elastomer resin has an average particle size of 60 to 80μ, a variation range of particle size of 10 to 300μ, and a thickness of the spherical wall surrounding the hollow part of 0.5 to 5μ. It must form a certain hollow fine sphere, and it must be blended into the polyurethane elastomer resin solution so that it accounts for 50% by weight or less. Inorganic silicates are mainly composed of silicon dioxide, sodium dioxide, and diboron trioxide. The polyurethane elastomer resin solution is applied to the base material, heated at 80 to 150°C for 15 seconds to 5 minutes,
A film is formed and solidified. Applications include transfer coat, doctor knife coat,
This is done by roll coating, flow coating, spray coating, etc. As the base material, flexible sheet base fabrics such as woven fabrics, knitted fabrics, non-woven fabrics, fibrous paper, asbestos paper, plastic films, metal foils, as well as iron plates, plywood, slate plates, etc. are used. Polyurethane elastomer resin has a molecular weight of 500
~3000 saturated polyester, polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polycaprolactone, etc. The base resin is a polyol having hydroxyl groups at both end groups, and glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, etc. or hexamethylene diamine, tolylene diamine,
A polymer consisting of a diamine chain extender such as diphenylmethane diamine and isophorone diamine, and tolylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate;
This polymer is used as a dissolved product in an organic solvent such as ethyl acetate, butyl acetate, dimethylformamide, or tetrahydrofuran, or as an emulsion type resin solution dispersed in water. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Ethylene adipate (1 mol) with a molecular weight of 2000, ethylene glycol (3.3 mol), and diphenylmethane diisocyanate (4.3 mol) were polymerized in dimethylformamide to achieve a solid content of 30% and a viscosity of
Produce 80000cp/25℃ polyurethane elastomer solution. Next, hollow spheres of inorganic silicate with a wall thickness of 0.5 to 5 μm (average 3 μm) are carefully selected to have a particle size of 10 to 200 μm, and further blended so that the average particle size is 65 μm. Add 10% by weight of the above to the polyurethane elastomer solution, add methyl ethyl ketone, stir and mix with Isper to adjust the viscosity to 10,000 cp/25°C to prepare a polyurethane elastomer resin solution, and process this to obtain the finished resin film thickness. Using a doctor knife, apply the resin onto the release paper so that it has a thickness of 80μ, and at the same time, layer 10μ of nylon taffeta on the resin-coated surface, press it with a pressure roller, and heat to 130℃.
After heating for 1 minute and leaving it for 24 hours, the release paper was peeled off, and a suede-like resin film was thus formed on the nylon taffeta. The inorganic silicate hollow spheres used in this example have a specific gravity of 0.18, a water absorption rate of (88% PH, 25°C), an oil absorption rate of 35 (g, oil/100cm ³ ), and a thermal conductivity of but
It was 0.3 “K” (BTU-in/ft ²゜hr〓). Example 2 Using the polyurethane elastomer produced in Example 1, (1) one containing 10% by weight of the inorganic silicate hollow spheres used in Example 1, (2) 10% of pulp powder with an average particle size of 130μ (Comparative Example 1), (3) 10% by weight of porous calcium carbonate powder with an average grain size of 100μ (Comparative Example 2), (4) No fine powder (Comparative Example 3) ), Add methyl ethyl ketone to the above four types of resin solutions to adjust the viscosity to 10,000 cp/25°C, apply each onto release paper using a doctor knife so that the finished resin film thickness is 100 μm, and heat at 120°C. The film was heated for 2 minutes, rolled up and left to stand for 24 hours, and then the release paper was peeled off to produce four types of polyurethane resin films. The physical properties of these polyurethane resin films are shown in the table below. The polyurethane resin film of the present invention (Example 2), which is composed of inorganic silicate hollow spheres, is different from pulp (Comparative Example 1) and calcium carbonate (Comparative Example 1). Compared to the polyurethane resin film of the comparative example composed of Example 2), it has higher physical properties, especially higher expansion force and elongation, and excellent elasticity, flexibility, abrasion resistance, and crack resistance. In addition, the inorganic silicate hollow spheres have both water absorption and oil absorption, and have a lower specific gravity and lower thermal conductivity than polyurethane resin. Compared to Comparative Example 3), it was lighter and had a better feel, and had physical properties and texture suitable for the skin of synthetic leather.

〔Effect of the invention〕

As is clear from the above, the effects of the present invention are produced as follows. (1) The inorganic silicate compounded in polyurethane elastomer resin has an average particle size of 60 to 80μ and a particle size distribution range of 10
It is a round hollow sphere with a diameter of ~300μ and a wall thickness of 0.5~50μ, and its content is less than 50% by weight of the total solid content, so inorganic silicic acid is absorbed inside the skin of synthetic leather made of polyurethane elastomer resin. Even if the salt hollow spheres make point contact, they do not become entangled, and when external stress acts on the synthetic leather, the hollow spheres slide through the polyurethane elastomer resin, thereby reducing the applied elastic stress, refraction stress, or Frictional stress is alleviated, and thus synthetic leather can be obtained that satisfies the physical properties required for the outer skin of personal items, such as flexibility, elasticity, crack resistance, and abrasion resistance. (2) As described above, the synthetic leather according to the present invention is flexible and highly elastic, but at the same time, the inorganic silicate compounded in the polyurethane elastomer resin contains silicon dioxide, sodium dioxide, and diboron trioxide. It is composed as a main material and has both affinity and hydrophilicity, and since it forms a hollow round sphere, it has a lower specific gravity and lower thermal conductivity than polyurethane resin, and therefore has a light volume that closely resembles natural leather. Synthetic leather with a pleasant feel and texture can be obtained. (3) Inorganic silicates have both affinity and hydrophilicity and exhibit extremely good compatibility with polyurethane elastomer resins.Moreover, since they form hollow spheres with an average particle size of 60 to 80 μm, they can be used as base materials. When applied to the skin, it can be applied smoothly and extremely thinly without scratching, thereby producing synthetic leather with a thin and smooth epidermis. (4) The inorganic silicate compounded in the polyurethane elastomer resin is a round hollow sphere with a wall thickness of 0.5 to 50μ, and the hollow sphere does not break or deform during the heating process to solidify the applied polyurethane elastomer resin. Unlike the conventional wet method in which dimethylformamide is extracted to form a porous film while retaining its spherical form, the extraction device is a hot water washing device or dimethylformamide. Synthetic leather with a porous film in which air bubbles are finely and uniformly dispersed can be obtained in a non-polluting and efficient manner without the need for equipment investment such as an amide recovery device. Thus, according to the present invention, synthetic leather with excellent physical properties such as water resistance, flexibility, abrasion resistance, and crack resistance, with a touch and feel very similar to natural leather, and with an ultra-thin and smooth skin is economical. Obtained efficiently. As is clear, the present invention has strong physical properties that can be used as practical products such as bags such as bags and handbags, footwear such as shoes and sandals, clothing such as jumpers and suits, and chair upholstery and seat covers. This is particularly advantageous for the production of synthetic leather used as a surface material that requires a good feel to the touch as a disposable item and a smooth and beautiful appearance as a decorative item.

Claims (1)

[Scope of Claims] 1 Main component is inorganic silicate, and the average particle size is 60 to 80.
microscopic hollow spheres with particle size variation ranging from 10 to 300 μ and a thickness of the sphere wall surrounding the hollow part from 0.5 to 5 μ, with a solid content ratio of 50% by weight.
1. A method for producing synthetic leather, which comprises applying and laminating a polyurethane elastomer resin solution blended as follows onto a base material and heat-treating the solution to form a surface film of polyurethane elastomer resin. 2. The synthetic leather according to claim 1, wherein the inorganic silicate according to claim 1 is mainly composed of silicon dioxide, sodium dioxide, and diboron trioxide. manufacturing method.