JPH04194085A - Synthetic leather and its production - Google Patents

Abstract

PURPOSE:To obtain a synthetic leather having extremely soft texture and close resemblance to natural leather by using a base cloth fluffed on one surface, applying a polyurethane on the reverse side of the cloth by wet-coagulation, laminating a wet fine porous layer of polyurethane on the surface of the cloth and integrating the layers. CONSTITUTION:A base cloth such as woven or knit cloth or nonwoven cloth made of natural fiber, regenerated fiber, synthetic fiber, etc., is fluffed preferably at both surfaces. A surface of the fluffed base cloth is coated with an organic solvent solution of a polyurethane resin and the cloth is immersed in water to remove the solvent and coagulate the polyurethane resin. The other surface of the base cloth is coated with a water-miscible organic solvent solution of a polyurethane elastomer and immersed in water to thoroughly remove the organic solvent and form a fine porous layer by wet process. A synthetic leather having close resemblance to natural leather can be produced by this process. The process can easily cope with the production of variety of products in small quantities compared with conventional process.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to synthetic leather and a method for producing the same.

[Conventional technology and Problems that the invention seeks to solve]

Synthetic leather is known in which a wet microporous layer of polyurethane resin is formed on the surface of an elastic base material that integrates a base fabric such as woven fabric, nonwoven fabric, or knitted fabric with polyurethane resin. Conventionally, the manufacturing method is to immerse the base fabric in an impregnation tank filled with a water-miscible organic solvent solution of polyurethane resin to impregnate the base fabric with the polyurethane resin solution, and then reduce the amount of polyurethane resin solution in the base fabric. is squeezed out to a predetermined amount, and then immersed in water to solidify the polyurethane resin to form an elastic base material. After that, a solution of the polyurethane resin in a water-miscible organic solvent is applied to the surface of the base material. ,
A method is known in which a wet microporous layer is formed by coagulating this polyurethane resin in water.

However, in the conventional manufacturing method described above, in the process of manufacturing the elastic base material, the base fabric is immersed in an impregnating bath filled with a solution of a water-miscible organic solvent of polyurethane resin.
It is necessary to prepare more processing liquid than is actually required,
A lot of processing liquid is wasted. In addition, if it is necessary to color synthetic leather, a coloring agent such as a pigment is added to the polyurethane resin treatment solution in advance, but with conventional methods, it is necessary to prepare more than the necessary amount of treatment solution. Therefore, although there are relatively few problems when mass-producing synthetic leather of the same color, it cannot be said to be suitable as a method for producing small quantities of multi-colored synthetic leather.

The present invention solves the above-mentioned problems and provides a manufacturing method with less waste of processing liquid even in the case of multi-colored, small-scale production, and also provides synthetic leather that is more flexible and has an excellent texture than conventional synthetic leather. purpose.

[Means to solve the problem]

That is, the synthetic leather of the present invention is made by wet coagulating the polyurethane resin by immersing a water-miscible organic solvent solution of a polyurethane resin applied on the back side of a base fabric whose front side is raised at least in water. A wet microporous layer of polyurethane is integrally laminated. In addition, the method for producing synthetic leather of the present invention includes applying a water-miscible organic solvent solution of a polyurethane resin to the back side of a base fabric whose surface side is brushed, and then immersing it in water to wet-coagulate the polyurethane resin. It is characterized in that a solution of a polyurethane resin in a water-miscible organic solvent is coated on the side, and then the polyurethane resin is wet coagulated by immersion in water to form a wet microporous layer.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Fig. 1, reference numeral 1 denotes a base fabric, and the base fabric 1 is one that has been subjected to a napping treatment on at least the front side (located on the bottom side in Fig. 1), but the napping treatment is applied to both sides. Preferably. As the base fabric 1, woven fabrics, non-woven fabrics made of natural fibers such as cotton and linen, recycled fibers such as rayon, acetate, and cotton wool, and synthetic fibers such as polyamide, polyester, and polyacrylonitrile, alone or in combination with these fibers,
A knitted fabric or the like can be used. As the base fabric 1, JIS
Water absorption by L1096C method is within 60 seconds, JIS
L1096A method Niyol breathability force 1 dllcd/l
The one above is preferred.

In the method of the present invention, a solution of a polyurethane resin in a water-miscible organic solvent is first applied to the back surface of the base fabric 1 (in the case of a single-sided raised fabric, the side that has not been subjected to the napping treatment) using a knife coater 2 or the like.

As the polyurethane resin, polypropylene glycol polyurethane, polytetramethylene glycol polyurethane, polycarbonate polyurethane, polytetramethylene glycol-polycarbonate copolymer polyurethane, etc. can be used. Of these,
For the coating on the back side of the base fabric 1, polypropylene glycol polyurethane is used from the viewpoint of cost when the final synthetic leather is used for furniture, and polycarbonate, which has good heat resistance, is used when it is used for vehicle interiors. Polyurethane-based polyurethanes are preferred. Also, 100% modulus is 15~
150 kg/C1fi polyurethane resin is preferred.

As the water-miscible organic solvent used as a solvent for the polyurethane resin, an organic solvent that dissolves the polyurethane resin and is miscible with water is used, such as dimethylformamide (DMF) and dimethylacetamide (DMA).
, tetrahydrofuran (THF), dioxane (D.

X) and mixtures thereof, but usually DMF
is used. The polyurethane resin solution applied to the back side of the base fabric 1 has a viscosity of 500 to 3000 at 25°C.
cps is preferable, and the coating amount per unit area of the base fabric 1 is preferably 30 to 200 g/bo in terms of the solid content of the polyurethane resin.

The base fabric 1 coated with the water-miscible organic solvent solution of the polyurethane resin on the back side is immersed in water in the coagulation tank 3 to remove the solvent and coagulate the polyurethane resin.
A base material 4 having a polyurethane resin integrated therein is obtained.

Next, a solution of a polyurethane resin in a water-miscible organic solvent is applied to the front side of the base fabric 1. Following the application of the polyurethane resin solution to the back side of the base fabric 1 and the coagulation treatment of the polyurethane resin, the solution is applied to the front side of the base fabric 1. When applying the polyurethane resin solution, it is preferable to pass the base fabric 1 (base material 4) through the reversing device 5 and turn it over so that the front side of the base fabric 1 faces upward.

The polyurethane resin solution can be applied to the surface side of the base fabric 1 using a knife coater 6 or the like, and after applying the polyurethane resin solution, it is immersed in water in a coagulation tank 7 to remove the solvent and coagulate the polyurethane resin. As a result, a wet microporous layer is formed.

As the polyurethane resin for forming this wet microporous layer, the same ones as mentioned above can be used, but
In particular, when synthetic leather is used for furniture, polytetramethylene glycol polyurethane, polycarbonate polyurethane, and polytetramethylene glycol-polycarbonate copolymer polyurethane, which have excellent hydrolysis resistance and improved durability, are recommended. Preferably, polycarbonate polyurethane, which has excellent heat resistance, is preferred when used for vehicle interiors. Moreover, a polyurethane resin having a 100% modulus of 20 to 150) cg/ctfl is preferable. As the water-miscible organic solvent used as a solvent for the polyurethane resin, the same organic solvents as mentioned above are used. The polyurethane resin solution applied to the surface side of the base fabric 1 has a viscosity of 800 to 1000 at 25°C.
0 cps is preferable, and the coating amount per unit area of the base fabric 1 is preferably 100 to 500 g/nf in terms of the solid content of the polyurethane resin.

Figure 2 shows the synthetic leather 8 of the present invention obtained as described above.
An example is shown in which 9 is a polyurethane resin layer formed by solidifying a polyurethane resin solution applied to the back side of the base fabric 1, and 10 is a wet microporous layer. Part or all of the polyurethane resin applied to the back side of the base fabric 1 may be impregnated into the base fabric 1 and integrated with the base fabric 1 to form the base material 4. Therefore, the polyurethane resin layer 9 does not necessarily need to be formed on the back side of the base fabric 1. In the case where part or all of the polyurethane resin applied to the back side of the base fabric 1 is impregnated into the base fabric 1 and integrated with the base fabric 1, it is unclear to what extent the polyurethane resin has penetrated into the base fabric 1. However, in the case of the synthetic leather 8 of the present invention, the polyurethane resin applied from the back side does not penetrate to the front side of the base fabric 1, or even if it does, the density of the polyurethane resin decreases as it approaches the front side. is lower than that on the back side, and it is considered that the overlapping portion of the warp and weft of the base fabric 1 is not completely hardened by the polyurethane resin.

As shown in FIG. 3, the synthetic leather 8 of the present invention can be given a suede-like appearance by further polishing the surface of the wet microporous layer 10. Furthermore, a surface treatment layer 11 for stain prevention can be provided on the polished surface. In the case of a suede-like finish, the polyurethane resin for forming the wet microporous layer 10 described above is preferably a non-yellowing type. The surface treatment agent for forming the surface treatment layer 11 is preferably a non-yellowing silicone-modified polyurethane, a non-yellowing fluorine-modified polyurethane, a non-yellowing amino acid-modified polyurethane, or the like. The surface treatment layer 11 is usually formed by gravure coating, a screen method, etc.The surface treatment layer 11 usually contains a surface treatment agent in a solid content of 2 to 20 g.
/M is preferable. The suede-like synthetic leather 8 may be subjected to embossing using an embossing roll or the like after the surface treatment layer 11 is formed.

FIG. 4 shows still another example, showing a synthetic leather 8 in which a surface treatment layer 11 is provided after a skin layer 12 is formed on the surface of a wet microporous layer 10 by a dry method.

The skin layer 12 by the dry method is formed by a transfer method in which a polyurethane resin solution is applied onto a release paper, dried, and then bonded to the surface of the wet microporous layer 10 by heating and pressure, and then the release paper is peeled off. be able to. Although not particularly shown in the drawings, it is also possible to sequentially provide two layers of polyurethane resin, an intermediate skin layer and a skin layer 12, by a dry process on the surface side of the wet microporous layer 10.

In this case, first, a solution of a polyurethane resin for forming a skin layer is applied onto a release paper and dried, and then a solution of a polyurethane resin for forming a middle skin layer is applied and dried, and then heated and dried on the surface of the wet microporous layer 10. A method can be adopted in which the release paper is peeled off after pressurizing and crimping.

The polyurethane resin for forming the skin layer 12 is preferably a non-yellowing type. Also, surface treatment layer 1
In addition to normal polyurethane, non-yellowing silicone-modified polyurethane can be used as a surface treatment agent for forming 1.
Non-yellowing fluorine-modified polyurethane, non-yellowing amino acid-modified polyurethane, etc. can be used.

The present invention will be explained in more detail by giving specific examples below.

Example 1 Polypropylene glycol was used as the polyol component on one side of a 0.9 m thick double-sided raised fabric woven in a twill weave using 20 count double-handed yarns made of a blend of polyester fibers and cotton fibers, and the 100% modulus was 60) cg/d. A 10% DMFi solution (containing 3 parts by weight of colorant per 100 parts by weight of elastomer) of polyurethane elastomer was applied using a knife coater so that the coating amount was 50 g/nf in terms of urethane solid content, and then soaked in water at 20°C. The polyurethane was immersed in water to remove the solvent, solidify the polyurethane, and after dehydration, it was dried under hot air at 120°C to obtain a base material with a thickness of 0.95 mm.

Next, a 15% DMF solution of a polyurethane elastomer with a 100% modulus of 50 kg/cd containing polytetramethylene glycol as a polyol component (3 parts of colorant per 100 parts by weight of elastomer) was applied to the side opposite to the side to which the polyurethane resin solution was applied. parts by weight, 2 parts by weight of surfactant, and 5 parts by weight of filler) using a knife coater.
After coating so that the coating amount was 250 g/rrf in terms of urethane solid content, it was immersed in water at 20 ° C.
The DMF in the polyurethane solution applied by immersion in warm water at °C was removed by thorough extraction into water. After dehydration, 12
Dry under hot air at 0℃ and have a microporous layer on the surface with a thickness of 1
．． 1 m of synthetic leather was obtained. The obtained synthetic leather had excellent flexibility and good texture.

On the other hand, a 23% DMF/toluene solution of a non-yellowing polyurethane elastomer containing 1,6-hexane carbonate glycol as a polyol component and having a 100% modulus of 90 kg/Cla. (containing 5 parts by weight of agent) was applied to a dry thickness of 10JIM, and dried with hot air at 90°C for 1.5 minutes to form a layer that would become a skin layer. Next, on top of this layer which will become the epidermal layer, polytetramethylene glycol is used as the polyol component, and the 100% modulus is 40 kg/c.
A 21% DMF/methyl ethyl ketone (MEK) solution of the polyurethane elastomer of d (containing 5 parts by weight of crosslinking agent, 20 parts by weight of colorant, and 0.5 parts by weight of light stabilizer per 100 parts by weight of elastomer) was added to a dry thickness of 25 nm. After coating with a knife coater and drying with hot air at 90"C for 2 minutes to form a layer that will become the mid-skin layer, the microporous layer surface of the synthetic leather is heated to 140°C and bonded by thermocompression to the microporous layer surface to be laminated. After that, the release paper was peeled off to obtain a synthetic leather having a leather drawing pattern on the surface by transferring and forming a medium layer and a surface layer on the microporous layer in that order.The obtained synthetic leather was It has a soft texture and a sense of unity. When this synthetic leather is rubbed under thermal conditions, it has an even softer texture, drapability, and wrinkles. It has a soft texture and appearance that retains its wrinkles for a long period of time, and it has excellent hydrolysis resistance.
It also had excellent durability such as light resistance, and was suitable as a furniture sheet material.

After this synthetic leather is kept in an atmosphere of 90% relative humidity and 70"C for 10 weeks, there are very few changes in physical properties such as appearance, texture, taper abrasion loss, and peel strength. Even after conducting an ultraviolet irradiation test for 200 hours at a temperature of 63°C, there were few changes in physical properties, and in both cases, taper wear loss,
The retention rate of various physical properties of peel strength (ratio of the measured value after the test to the measured value before the test) was 80% or more.

Example 2 One side of a double-sided raised fabric with a thickness of 0.85 mm, which was woven in a twill weave using a 20-count double-woven fabric made of a blend of polyester fiber and rayon fiber, was coated with 1.6-hexane carbonate glycol as a polyol component.

A 10% DMF solution of a polyurethane elastomer with a % modulus of 30 kg/cii (containing 5 parts by weight of colorant per 100 parts by weight of elastomer) was coated with a knife coater.
The coating amount was 70 g/n (converted to urethane solid content), and then the polyurethane was immersed in water at 20°C to remove the solvent and solidify the polyurethane.
The surface of the raised surface was corrected by turning it 0° and heating the raised surface side, which has not been coated with the polyurethane resin solution, along a heating roll in order to lay the raised surface in a certain direction and improve surface smoothness. A sheet with a thickness of 0.8 m was obtained. Next, on the side opposite to the side to which the polyurethane resin solution was applied, a 100% modulus of 40 kg/1,6-hexane carbonate glycol was applied as a polyol component.
ELL's non-yellowing polyurethane elastomer 18%D
MF solution (20 parts of colorant per 100 parts by weight of elastomer)
parts by weight, 2 parts by weight on the surfactant side, and 3 parts by weight on the filler) using a knife coater so that the coating amount was 320 g/bo in terms of urethane solid content, and then immersed in water at 20 °C. Then, the DMF in the polyurethane solution applied by immersion in 60°C warm water was extracted into water and thoroughly removed. After dehydration, it was dried under hot air at 120° C. to obtain synthetic leather having a thickness of 1.1 m and having a microporous layer on the surface. The obtained synthetic leather had excellent flexibility and a good feel.

Next, the surface layer of the microporous layer of this synthetic leather was polished using a 180-mesh belt sander to obtain a suede-like surface. A fluorine-modified polycarbonate-based polyurethane surface treatment agent is applied to this surface using a gravure roll.
After forming a surface treatment layer so that the solid content per unit area was 5 g/rrf, the surface was embossed with an embossing roll having a pore squeeze handle to obtain suede-like synthetic leather. The resulting synthetic leather has a soft texture with a sense of unity and flexibility, closely resembling natural leather in appearance, and has durability such as hydrolysis resistance, light resistance, and heat resistance. It was suitable for use as a sheet material for furniture and vehicles.

This synthetic leather showed changes in physical properties such as appearance, texture, Taber abrasion loss, and peel strength after being kept in an atmosphere of 90% relative humidity and 70°C for 10 weeks using a fade meter (panel temperature of 83°C). Changes in appearance, texture, and various physical properties after 400 hours of ultraviolet irradiation test in a 400-hour ultraviolet irradiation test, as well as changes in appearance, texture, and various physical properties after being heated and held in a gear oven (120°C) for 400 hours. The retention rate of various physical properties was 80% or more in all cases.

Comparative Example °1 The same double-sided raised fabric as in Example 1 was made with polypropylene glycol as the polyol component, and the 100% modulus was 60k.
g/cj of polyurethane elastomer per 100 parts by weight of fiber by immersing it in an impregnating bath filled with a 10% DMF solution (containing 3 parts by weight of colorant per 100 parts by weight of elastomer), and then using a squeeze roll to impregnate the polyurethane elastomer with the polyurethane solution. After squeezing the polyurethane elastomer to an amount of 25 parts by weight, it was immersed in water at 20°C to remove the solvent and coagulate the polyurethane.

Next, a wet microporous layer of polyurethane was formed on the surface of this sheet in the same manner as in Example 1 to obtain synthetic leather. Although this synthetic leather has excellent durability, it has a hard texture and lacks a sense of unity.

〔Effect of the invention〕

As explained above, the synthetic leather of the present invention is softer and has an excellent sense of unity than conventional synthetic leather, and has a feel more similar to natural leather than conventional synthetic leather. Furthermore, the method of the present invention has the effect of producing synthetic leather having the above-mentioned excellent feel. Furthermore, compared to conventional methods, the method of the present invention has the advantage that it is easier to cope with the production of a variety of products in small quantities in a variety of colors, and the waste of the polyurethane treatment solution can be reduced.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is a schematic diagram showing the manufacturing method of the present invention, FIG. 2 is a longitudinal sectional view showing one embodiment of the synthetic leather of the present invention, and FIGS. 3 and 4 are respectively It is a joint sectional view showing another example of the synthetic leather of the present invention. 1... Base fabric 2.6... Knife coater 3.7...
・Coagulation tank 8...Synthetic leather 10...Wet microporous layer Fig. 4

Claims (2)

[Claims] (1) Wet-coagulate polyurethane resin on the surface side of the base material by soaking a water-miscible organic solvent solution of polyurethane resin in water to wet-coagulate the polyurethane resin applied to the back side of the base fabric whose surface side is raised at least. Synthetic leather characterized by an integrally laminated microporous layer. (2) After applying a water-miscible organic solvent solution of polyurethane resin to the back side of the base fabric whose front side is raised,
Wet-coagulate the polyurethane resin by immersing it in water, then apply a water-miscible organic solvent solution of the polyurethane resin on the surface side, and then wet-coagulate the polyurethane resin by immersing it in water to form a wet microporous layer. A method for producing synthetic leather characterized by: