JPS61207675A - Production of improved leather-like material - Google Patents

Abstract

PURPOSE:To obtain a leather-like material having excellent durability and feeling, and elegant surface appearance, by impregnating a specific urethane solution containing a specific amount of nitrogen atom originated from isocyanate group into a piece of cloth and coagulating the solution under stretching. CONSTITUTION:A solution of a polyurethane composed of (A) a polymer diol composed mainly of poly-3-methylpentane adipate having a molecular weight of 500-3,000 (B) a 2-6C low-molecular diol and (C) 4,4'-diphenylmethane diisocyanate and containing 3.5-6wt%, preferably 4.0-5.0wt% nitrogen atom originated from the isocyanate group in said urethane, is impregnated in and/or applied to a piece of cloth (especially nonwoven cloth of ultrafine fiber). The clock is stretched longitudinally by 0-10%, and immersed under tension in a non-solvent of said polyurethane (e.g. water) or in a texture of solvent and non-solvent to effect the coagulation of polyurethane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a leather-like material having improved durability and hand and a graceful surface.

[Prior art]

BACKGROUND ART Conventionally, methods for producing leather materials by wet coagulation of polyurethane have been widely known.

[Problem that the invention seeks to solve]

However, conventional leather-like materials have the following drawbacks, mainly related to polyurethane.

Although polyether polyurethane has excellent hydrolysis resistance, low modulus polyurethane has poor coagulation properties and is not satisfactory for applications that require a smooth surface and softness. In addition, polyether polyurethane not only has poor heat resistance, but also has many drawbacks, such as swelling with solvents such as toluene and perchloromethane.

For this reason, in the manufacturing method of artificial leather with excellent flexibility and texture,
A non-woven fabric of multicomponent fibers is impregnated with a polyurethane solution and (
After coating and wet coagulation, it is necessary to extract and remove at least the fiber component with toluene or perchlorene, but when polyether-based polyurethane is used, The fine pores of the polyurethane phase were destroyed, making it impossible to obtain a smooth surface, and the moisture permeability, which is a characteristic of artificial leather, was also reduced.

On the other hand, conventional polyester polyurethanes have good heat resistance and stability against solvents such as toluene and perchloren, but have a drawback of poor hydrolysis resistance. Further, although the coagulation properties of conventional polyester polyurethanes are said to be slightly improved compared to polyether polyurethanes, they have not been fully satisfactory. In other words, in order to improve coagulation properties, it is common to increase the proportion of nitrogen atoms in polyurethane, but increasing the proportion of nitrogen atoms improves coagulation properties and improves surface smoothness. Although it improved, it had the disadvantage that the texture was not hard and it was impossible to make soft items. For this reason, it is necessary to adopt conditions that balance both solidification and texture, but the stability conditions for both are extremely narrow, making it difficult to industrially and stably manufacture superior products. . In recent years, there has been an increasing demand for synthetic leather to be softer, and efforts have been made to improve the feel of conventional polyester-based polyurethane by reducing the proportion of nitrogen atoms in the polyurethane. However, even if the coagulation property is improved by reducing the proportion of nitrogen atoms, the cohesive force of the hard segments is small due to the low concentration of the hard segments. The domain was destroyed and a smooth surface could not be obtained as a final product.

Despite this technological level, the performance requirements for leather-like materials are becoming increasingly strict: materials with smooth surfaces, good texture, and excellent solvent resistance, heat resistance, and hydrolysis resistance. There is no end to the demand for I.

[Means for solving problems]

As a result of intensive research in order to provide a comprehensively superior leather-like material to meet these many demands, the present inventor, Hirohiro, has developed a polymer diol mainly consisting of poly-3 methylpentane adipate and a material containing 2 to 2 carbon atoms. 6 low molecular weight diol and 4.
After impregnating or (and) applying a solution of a specific polyurethane consisting of 4'-diphenylmetallidiisocyanate to a fabric such as a non-woven fabric or #i woven fabric, it is soaked in a mixed solvent of a polyurethane solvent and a non-solvent, or a non-solvent. They discovered that the leather-like material obtained by soaking and coagulating the material has surprising properties such as excellent surface smoothness, texture, and hydrolysis resistance. It has also been found that the smoothness of the surface can be further improved by using specific coagulation conditions. Furthermore, the sheet material produced by MI by hardening with this method has a smooth texture even if it is treated with toluene or perchloren after solidification.

It was also discovered that it has an excellent property of maintaining moisture permeability, which has never been seen before.

The present invention will be explained in more detail below.

The fabric used in the present invention is not limited in terms of percentage, but from the viewpoint of feel etc., it is preferable to use an ultrafine fiber nonwoven fabric or a multicomponent fiber nonwoven fabric that can be made into ultrafine fibers in a subsequent process. '! 'ta, PV
Aqueous solutions such as A (polyvinyl alcohol) and CMC (carboxylated methylcellulose), acrylic esters,
It is also effective to use a running nonwoven fabric pretreated with an aqueous dispersion of polyurethane or the like.

The polymer diol used in polyurethane has a molecular weight of 5.
Poly-3-methylbenone adipate obtained from 00 to 3000 3-methyl 1,5-bentanediol and adipic acid, but other polymer diols may be mixed up to about 15% by weight or less of the total polymer diol. can. For example, by using a mixture of 90 parts by weight of poly-3 methylpentane adipate and polyethylene glycol of 0 weight Jls, it is possible to further impart dyeability while retaining the excellent performance of poly-3 methylpentane adipate. It is. It is also possible to use a mixture of 10 parts by weight of poly-gamma-valerolactone diol to significantly improve the mold resistance.As the amount of other polymer diols increases, the amount of poly-3-methylpentane increases. The excellent coagulation properties and solvent resistance of adipate will be impaired.

As the low molecular diol, a low molecular diol having 2 to 6 carbon atoms is used. Polyurethane using 3-methylpentane adipate has a slower aggregation speed of hard segments than normal ester-based polyurethane, so it is difficult to form hard segments with strong cohesive force. On the other hand, if the cohesive force of the bar)° segment is weak, the hard domains may be destroyed by perchloren or toluene treatment, making it impossible to obtain a smooth surface when split into pieces. Therefore, as a low-molecular diol, the number of carbon atoms is 2, which allows the hard segment to exhibit strong cohesive force.
Low-molecular diols having a molecular weight of 6 to 6 are preferred, and ethylene glycol and 1,4-butanediol are particularly preferred.

As the diisocyanate, 4,4'-diphenylmethane diincyanate is used. In order to improve coagulation properties, it is important to adjust the balance between the compatibility of the soft and hard segments of the polyurethane, the phase separation rate, and the cohesive force of the hard segments, as described above. When 3-methylbentanediol is used as the soft segment, the hard segment made of the above-mentioned low-molecular-weight diol 4,4'-diphenylmethane diincyanate has an excellent overall balance. Other incyanates have poor balance and poor coagulability.

The method for producing polyurethane of the present invention is not particularly limited. A solution polymerization method in which the polyurethane raw material is placed in t-N,N'-dimethylformamide and the polymerization reaction is carried out, and a melt polymerization method in which the polymerization reaction is carried out at a high temperature (lower than the melting point of the polyurethane raw material and the reaction product in a hot solvent) are used. In either method, the weight proportion of nitrogen X atoms based on isocyanate groups in the polyurethane is limited to a range of 3.5% to 6.0%. Especially 4. Oq6 to 5
．． A range of 0% is preferred. The proportion of nitrogen atoms is 3.5%
If the content of y) is too low, not only mechanical properties such as strength and elongation will deteriorate, but also coagulability, heat resistance, and solvent resistance will decrease, which is not preferable. In addition, when the amount is more than 6.0%, mechanical properties, coagulation properties,
Solvents for polyurethane, which have excellent heat resistance and solvent resistance but have a hard texture and do not yield excellent leather-like materials, are not particularly limited (N, N'-dimethylformamide, N, Commonly used solvents such as N/-dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, etc. can be used.

Depending on the purpose, various additives such as surfactants, colorants, and stabilizers, and various polymers such as polyvinyl chloride and polyacrylonitrile may be mixed into the polyurethane solution.

Polyesters obtained from 3-methyl-1,5-bentanediol and dicarboxylic acids and polyurethanes obtained from organic diisocyanates and chain extenders are known and can be prepared by impregnating or coating a fabric with a solution of such polyurethanes. It is also known that a leather-like material can be obtained by wet coagulation (JP-A-47-34494 and JP-A-48-101496). The present invention is directed to the polyurethane described in such known documents, but only the polyurethane obtained by reacting with a specific raw material and a specific composition ratio can solve the problems of the present invention. In addition, it has been discovered that when such polyurethane is wet-coagulated under a specific coagulation temperature as described below, a sheet with even better one-sided smoothness, that is, an extremely excellent sheet as a leather-like material, can be obtained. It is.

Examples of the coagulation bath used in the present invention include a mixed solvent of the polyurethane solvent and a non-solvent, or one consisting only of a non-solvent; however, the non-solvent is not particularly limited; is preferred.

In addition, in the present invention, when the fabric is coagulated, the length direction KO~1
In order to obtain a smooth coagulated surface, it is preferable to perform coagulation while tensioning the fabric in the longitudinal direction so that the fabric is elongated by 0%.

A particularly preferred elongation rate is 3 to 7%. When the elongation rate of the fabric is outside the range of 0 to 10%, it becomes difficult to obtain a smooth coagulated surface.

In particular, when the elongation rate exceeds 10%, the texture of the resulting coagulated product also becomes hard. In order to keep the lengthwise elongation of the fabric during coagulation within the above range, the ratio between the speed at which the long fabric is fed into the coagulation bath and the speed at which it is taken out from the coagulation bath may be appropriately adjusted.

In addition, for sheet-like products produced by impregnating and coagulating polyurethane into a nonwoven fabric composed of multicomponent fibers, one component of the fibers can be extracted and removed with a solvent such as perchlorene, toluene, or trichlene, if necessary. The porous body obtained by wet coagulating the polyurethane has extremely high stability against such solvents, so even when treated with such solvents, the polyurethane sponge before treatment will not be destroyed and will retain its elegant appearance. It is possible to maintain even higher moisture permeability.

Thereafter, the sheet-like material can be subjected to various operations depending on the purpose. For example, a sheet-like material obtained by impregnating and coagulating the polyurethane solution into a nonwoven fabric made of a mixed IS fiber using polyethylene as the sea component and nylon-6 as the island component, and then extracting and removing the polyethylene with hot toluene. divide,
A suede-like leather-like material can be produced by puff-raising and dyeing the non-sliced surface.

Further, after impregnating the above nonwoven fabric with the polyurethane solution,
After applying the polyurethane solution and then extracting and removing the polyethylene with hot toluene, the surface of the sheet-like material obtained is coated with a finishing layer using gravure, spraying, etc., and then further embossed to produce a grain-faced leather-like material. can be manufactured. Such post-treatment does not substantially impair the excellent performance described above.

The leather-like material obtained by this method not only has superior texture and appearance compared to conventional materials, but also has excellent resistance to hot water deterioration and
It has extremely excellent solvent resistance, so if it is used in the shoe field, footwear field, or clothing field as a suede type, it can produce products that have a luxurious feel and are extremely durable. can.

Example: The sea component is polyethylene, the island component is nylon-6, and its
The quantity ratio is 50150, and the ultrafine fibers of the island component are 0.001 to 0.
01 denier sea-island type mixed spun fiber is melt-spun,
Moist heat stretching, winding, and cutting to obtain 51 lengths of 3.5 denier cotton, laminated with Shitanip and needle punched with a crease weight of 860? /cds apparent ratio i0.25
It was made into an entangled nonwoven fabric. This was heated and compressed so that the apparent specific gravity was 0.32 to stabilize the form of the nonwoven fabric.

A dimethylformamide solution of polyurethane having a molecular weight of about 2,000 and having a ratio of 4.0% to 4.4'-diphenyl-methane diincyanate and ethylene glycol was added to this nonwoven fabric. (13% viscosity f at 50'C]Op) in terms of solid content 4
0 parts impregnated and applied, and wet coagulated in a dimethylformamide-water mixture. The feed-in and take-out speeds were adjusted so that the lengthwise elongation of the fabric during hardening was 5%. )
Then, after dissolving and removing the polyethylene in hot toluene, it was sliced into two parts, the non-sliced side was brushed with a puff machine, and then dyed brown using an alloy dye to improve the appearance, texture, and texture.
A suede-like product with an excellent surface feel was obtained.

The comparative product is a product processed in the same way using polyurethane consisting of polytetramethylene glycol, 4,4'-diphenylmethane-diincyanate, and ethylene glycol with a molecular weight of about 2000 (comparative product 1), and a product with a molecular weight of about 20
00 polypterene adibe), 4,4'-diphenylmetallidiisocyanate, and ethylene glycol, which was also processed in the same way (comparative product 2). It is I@.

Table 1 shows the results of comparing the characteristics of the product according to the present invention and the comparative product.
It was shown to.

Table -] Rice 1 The strength retention rate was measured after exposure for 5 weeks at 70°C and 95%.

Brush 2 The strength retention rate was measured after 08 minutes of dry heating at 100°C.

The morphological changes after immersion in toluene at 390°C for 15 minutes were measured.

Rice 4: Discoloration and strength retention after fade irradiation were measured.

Example 2 A mixed spun fiber having a sea component of nylon-6, an island component of polystyrene, and a ratio of M'1 of 50150 was obtained by melt spinning, and this was dry-heat-rolled, crimped, and cut into lengths. The fabric was made of 5-denier cotton, laminated and intertwined by needle punching, impregnated with polyvinyl alcohol, and dried to obtain a nonwoven fabric with a stable shape.

In addition to this, the ratio of nitrogen fibers made of poly-3-methylpentane adipate, 4,4'-diphenylmethalidiisocyanate, and 1,4-butanediol having a molecular weight of about 2000 is 4.
After impregnating and applying 5J polyurethane and subsequently forming a coating layer, the fabric was coagulated in a dimethylformamide-water mixture so that the lengthwise elongation of the fabric upon coagulation was 4.5%. ), after removing polyvinyl alcohol and dissolving the polystyrene in hot toluene, slice it to an appropriate thickness, color the unsliced surface with a coating layer with pigment, and stamp it with an engraved roll to give it a pattern. It was made into a product.

The comparative products are two types of products processed using the same polyurethane as in Example 1 (Comparative Product 3 and Comparative Product 4).

Table 2 shows the results of comparing the characteristics of the product according to the present invention and the comparative product.
It was shown to.

Rice 1 to Rice 4 were prepared in the same manner as in Example 1.

Rice 5 Measured according to JIS-6545-1970.

Rice 6 Measured according to JIS-L-1096.

Claims (1)

[Scope of Claims] (1) A polymer diol mainly composed of poly-3-methylpentane adipate having a molecular weight of 500 to 3000, a low-molecular diol having 2 to 6 carbon atoms, and 4,4'-diphenylmetallidiisocyanate. After impregnating or (and) coating a fabric with a solution of polyurethane in which the weight proportion of nitrogen atoms based on isocyanate groups in the polyurethane is 3.5 to 6.0%, An improved method for producing a leather-like material, which comprises immersing the polyurethane in a non-solvent or a mixed solvent of a solvent and a non-solvent to coagulate the polyurethane. (2) The fabric is mainly composed of multi-component fibers made of two or more polymeric substances with different solubility in solvents, and the multi-component fibers are formed after coagulating the polyurethane. The manufacturing method according to claim 1, wherein a part or all of at least one component is extracted and removed. (8) The manufacturing method according to claim 1 or 2, wherein the fabric is coagulated under tension so that the fabric is stretched by 0 to 10% in the length direction during coagulation.