JPS5910380B2 - Method for producing sheet material with good durability and spongy structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing a sheet material of polyurethane elastomer which forms a good sponge structure layer and has good durability.

More specifically, the present invention relates to a polyurethane elastomer composition that stably forms a good sponge structure layer from a solution of a polyurethane elastomer obtained using polylactone glycol or polycarbonate glycol as a soft segment, and to coagulation conditions for the polyurethane elastomer solution layer. Conventionally, polyurethane elastomers have been widely used as one raw material for manufacturing leather-like sheet materials.

Polyester glycol or polyether glycol is used as the soft segment constituting the polyurethane elastomer. However, these polyurethane elastomers are generally limited to specific types due to their ability to form sponges by wet coagulation and the need to control the sponge structure. The object of the present invention is to produce a polyurethane elastomer sheet material from a polyurethane elastomer solution using a specific soft segment, by wet coagulation of the polyurethane elastomer solution, to form a stable and good sponge structure layer, and to have good bending resistance. It is an object of the present invention to provide a method for producing a sheet material that has good hardness, abrasion resistance, and hydrolysis resistance, has low temperature dependence, and is flexible and durable without tackiness.

The polylactone glycol obtained by ring-opening polymerization of lactone used in the present invention generally has a narrower molecular weight distribution than many other polyester glycols obtained by transesterification, and is used as a soft segment. Although polyurethane elastomers have relatively poor wet coagulation properties, the wet coagulation properties of these polyurethane elastomers could be improved by making them into blended polyurethane elastomers based on the present invention.

Further, polyurethane elastomers containing polycarbonate glycol as a soft cement also have wet coagulation properties similar to those of polylactone glycols, and therefore, they can be improved by forming blended polyurethane elastomers according to the present invention.

In the method of the present invention, the soft segment constituting the polyurethane elastomer is made of one kind of polymer glycol selected from polylactone glycol or polycarbonate glycol (hereinafter referred to as polymer glycol) having a molecular weight of 500 to 4000, and an organic diisocyanate and a chain. A polyurethane elastomer polymerized from an elongating agent, in which the weight of nitrogen atoms contained in the isocyanate group is 2% to 7.5% as a percentage (hereinafter referred to as N%) of the total weight of the polyurethane elastomer; The N% of the elastomers is 0.
Two or more types of polyurethane elastomers that differ by 2% or more but have the same chemical structural unit are mixed at 5 to 95% by weight each to produce a blended polyurethane elastomer with an average N% of 2.5% to 7% after mixing, A solution in which this polyurethane elastomer is dissolved is applied to a support or a support to form a solution layer, and the weight ratio of the solvent and non-solvent of the polyurethane elastomer is 20:80 to 70:
It is characterized by being immersed in a coagulation bath having a composition of 30% and coagulated into a sponge structure. As a result of intensive research on the wet coagulation properties of polyurethane elastomers, the present inventor found that the N% distribution (spread) of polyurethane elastomers
It has been clarified that the average value of the polyurethane elastomer has a large influence on the wet coagulation property of the polyurethane elastomer. That is,
．． In the polyurethane elastomer produced from the specific polymer glycol used in the present invention, when the N% is increased, the wet coagulation property is improved, but the Young's modulus becomes large and the material becomes hard, reducing the bending resistance. On the other hand, if flexibility is imparted by reducing the N%, the wet coagulation property will deteriorate, not only will it not be possible to obtain a good sponge structure, but also the abrasion resistance and temperature dependence will decrease. Therefore, in order to obtain a sheet material that satisfies both physical properties and sponge-forming properties that are suitable for application to a sheet material, especially a leather substitute material, it is simply a question of how to adjust the polymer glycol soft segment and N% constituting the polyurethane elastomer. Even if selected, one that satisfies both of these characteristics cannot be obtained. However, two or more types of polyurethane elastomers using polymer glycol as a soft segment and having the same chemical structural unit but different N% are synthesized separately, and then these polyurethane elastomers are mixed to form a blended polyurethane elastomer with a wide distribution of N%. It has been found that by doing so, it is possible to obtain a product that satisfies both wet coagulation properties and physical properties suitable for use as a leather substitute material.

In particular, the Young's modulus of such a blended polyurethane elastomer has less temperature dependence, making it more flexible and giving more favorable results in terms of abrasion resistance, bending resistance, etc. This is a truly surprising fact, as it shows that by widening the N% distribution of the polyurethane elastomer, its wet coagulation properties are improved as well as its physical properties. Examples of polymer glycols used as soft segments include butyrolactone, valerolactone,
Polylactone glycols obtained by ring-opening polymerization of lactones such as caprolactone, and aliphatic glycols such as propylene glycol, tetramethyl glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, P-xylene glycol, A polycarbonate glycol obtained by reacting one or two selected from ring-containing glycols or phenols such as 1,4-cyclohexanediethylene glycol and bisphenols with a carbonate having an active group, such as diethyl carbonate or phosgene. Polymeric glycol.

Further, as the organic diisocyanate used as the hard segment, aromatic diisocyanates such as naphthylene diisocyanate, diphenylmethane diisocyanate, diphenyl diisocyanate, tolylene diisocyanate, and xylylene diisocyanate are suitable, and other fatty acids such as hexamethylene diisocyanate are suitable. Group diisocyanates are also used. Examples of chain extenders having two active hydrogens in the Zelevitinoff reaction used for chain extension include glycols such as ethylene glycol, propylene glycol, butylene glycol, and hexamethylene glycol, 0,σ-dichloroP
, P'-diaminodiphenylmethane, m-phenylenediamine, 4-methyl-m-phenylenediamine, ethylenediamine, hexamethylenediamine and the like can be used, but glycols are preferred.

The N% distribution of the polyurethane elastomer is closely related to the molecular weight distribution of the soft segment, and the larger the molecular weight distribution of the soft segment, the broader the N% distribution of the polyurethane elastomer.

In the present invention, the N% of the two or more types of polyurethane elastomers having different N% to be mixed is not particularly limited, but is preferably in the range of 2% to 7.5%, with each other having a 0.0% N%.
It is necessary that the distance be 2% or more. This is a mutual N
If the difference in the percentages is small, mixing polyurethane elastomers with different N percentages will produce an effect, but the mixing operation will be complicated, so practicality was taken into consideration.
In addition, if the difference in N% is extremely different, when the mixed polyurethane solution is wet-coagulated, partial phase separation may occur and some coagulation spots may occur. Considering the above, it is preferable that the difference in N% between the polyurethanes that participate in more suitable mixing is in the range of 0.7 to 3.5%.

In addition, the amount of each polyurethane elastomer used in the mixing is 5 to 95% of the total amount of polyurethane elastomer after mixing.
The average N% of the blended polyurethane elastomer after mixing is preferably 2.5% to 7%, preferably 3% to 7%. It is 6%.

When the molecular weight of the soft segment is large, it is better to increase the average N%. In the present invention, it is preferable that the polyurethanes involved in the above-mentioned mixing have similar solubility in a solvent, and in particular, when their chemical structural units are the same, a particularly favorable result can be obtained.

Solvents for dissolving polyurethane elastomers include N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, tetramethylurea, dioxane, gamma-butyrolactone, and the like.

A non-thinning agent for polyurethane elastomer is used as a coagulation bath for coagulating the liquid of polyurethane elastomer, but if the non-thinning agent alone is used, the coagulation is too fast, resulting in an uneven reaction and the formation of a skin on the surface. It's easy to get wrinkles. To prevent this, use a mixture of anti-lok agents and laku agents,
Slower coagulation may be sufficient, but if the solvent content is too large, coagulation will be delayed and eventually coagulation will not be possible. Therefore, the appropriate composition of the coagulation bath is such that the weight ratio of the solvent to the thickening agent is in the range of 20:80 to 70:30.

Colorants, activators,
Various additives such as stabilizers and polymers such as polyacrylonitrile, polyvinyl acetate, polyvinyl chloride, polymethacrylate, polyacrylate, and vinyl halide polymers can be mixed.

The invention will be further explained below with reference to examples.

All parts and percentages are by weight unless otherwise indicated. Example 1 Polycaprolactone glycol (hereinafter abbreviated as PCL) with a molecular weight of 2000.

), 357 parts of P,P'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), and 66 parts of ethylene glycol to synthesize a polyurethane elastomer with an N% of 4.0. In addition, PCL46 with a molecular weight of 2000
A polyurethane elastomer with an N% of 5.0 was synthesized using 2 parts of MDI, 447 parts of MDI, and 91 parts of ethylene glycol. 11% of this polyurethane elastomer with N% 4.0,
11% polyurethane elastomer with N% 5.0, DMF
A liquid solution was prepared consisting of 76% stearyl alcohol, 1% stearyl alcohol, and 1% carbon black.

This solution was cast onto a glass plate to a thickness of 0.8 mm, and D
It was immersed in a coagulating solution at 50°C consisting of 50% MF and 50% water to solidify it, washed with water to remove DMF, and dried with hot air at 90°C. The obtained film had a smooth surface, a fine sponge structure of several microns in size, a soft texture, and good resistance to hot water and alkali.

Example 2 A polyurethane elastomer with an N% of 2.0 was synthesized using 804 parts of polycarbonate glycol with a molecular weight of 2000, 79 parts of MDIl, and 17 parts of ethylene glycol.

Polycarbonate glycol 46 with a molecular weight of 2000
A polyurethane elastomer with an N% of 5.0 was synthesized using 2 parts of MDI, 447 parts of MDI, and 91 parts of ethylene glycol. 10% of this N% 2.0 polyurethane elastomer,
10% polyurethane elastomer with N% 5.0, DMF
A solution consisting of 78% stearyl alcohol, 1% stearyl alcohol, and 1% carbon black was prepared.

This fermentation solution was cast onto a glass plate to a thickness of 1 ws, and DMF
It was immersed in a coagulating solution at 50°C consisting of 50% water and 50% water to solidify it, washed with water to remove DMF, and dried with hot air at 90°C. The obtained film has a smooth surface and a flexible texture due to its sponge structure, and even after being immersed in hot water at 90°C and left for 3 days, the degree of polymerization decreased only slightly, making it durable. It was a certain film.

In addition, this film is laminated onto a smooth leather substrate obtained by impregnating a fiber aggregate with polyurethane elastomer, and the surface is colored and embossed to create a leather-like sheet material with excellent surface abrasion resistance and resistance. It had good flexibility, excellent low-temperature properties, and good texture and wrinkle resistance.

Claims (1)

[Scope of Claims] 1. A polyurethane elastomer in which the soft segment constituting the polyurethane elastomer is composed of one type of polylactone glycol or polycarbonate glycol having a molecular weight of 500 to 4000, and which is polymerized with an organic diisocyanate and a chain extender, and the weight of nitrogen atoms contained in the isocyanate group is 2% to 7.5% in percentage (hereinafter referred to as N%) to the total weight of the polyurethane elastomer, and the N% of the polyurethane elastomers is 0.2% or more of each other. Two or more types of polyurethane elastomers that are different but have the same chemical structural unit are mixed in an amount of 5 to 95% by weight each to obtain a blended polyurethane elastomer having an average N% of 2.5 to 7 after mixing,
A solution in which this polyurethane elastomer is dissolved is applied onto a support or a substrate to form a solution layer, and the weight ratio of the solvent and non-solvent of the polyurethane elastomer is 20:80.
A method for producing a sheet material having good durability and a spongy structure, characterized by coagulating it into a spongy structure by immersing it in a coagulation bath having a composition of 70:30 to 70:30.