JPS6028301B2 - Method for producing porous sheet with good deterioration resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a flexible porous sheet with excellent deterioration resistance, particularly hydrolysis resistance.

More specifically, the present invention improves the wet coagulation property of a polyurethane elastomer solution by using at least two or more specific additives (coagulation regulators) in a solvent solution of a polyurethane elastomer having excellent hydrolysis resistance. significantly improved,
The present invention relates to a manufacturing method that provides a flexible porous sheet. Porous sheets obtained by green coagulation of polyurethane elastomer solutions are widely used as materials for artificial leather or synthetic leather (simply referred to as leather-like sheets).

When producing a porous sheet by the wet coagulation method, the most important thing is wet coagulation, for example, the formation of a desired uniform sponge structure within the polyurethane elastomer layer.
In addition, the surface is required to have good flatness. When wet coagulation is poor, the quality of the leather-like sheet made from the perforated sheet, especially the surface flatness, texture,
The folding edge and green transparency will be poor, and the commercial value will be significantly reduced. It is known that the wet coagulability varies greatly depending on the type of polyurethane elastomer used. For example, a polyurethane elastomer whose soft segment is a polyalkylene ester glycol obtained by a condensation reaction of a glycol with a small number of carbon atoms and a dicarboxylic acid. is relatively hydrophilic and has good wet coagulation properties. However, during use, leather-like sheets using this type of polyurethane elastomer undergo hydrolysis and deterioration due to water or bacteria such as mold, which not only greatly impairs the appearance, but also degrades the appearance. Things are happening right now where people are no longer able to perform their functions. Therefore, many attempts have been made to improve the coagulation properties of hydrophobic polyurethane elastomers, which have high resistance to deterioration, and use them in leather-like sheets. A method of adding higher alcohols, carboxylic acids, esters, ethers, ketones, polyalkylene ether glycols, etc. to a solution of polyurethane to the extent that the transparency of the solution is not lost, or adding a large amount of water-soluble substances to the solution of polyurethane. Methods such as colloidizing a polyurethane elastomer liquid with a non-solvent for the elastomer or adding salt to the coagulation phase have no effect or are somewhat effective on these hydrophobic polyurethane elastomers. However, it has not been successful due to drawbacks such as the difficulty in preparing the polyurethane elastomer solution and the poor stability of the polyurethane elastomer solution. A method of adding an anionic surfactant to improve the coagulation properties of the hydrophobic polyurethane elastomer has also been proposed, for example, in JP-A-51-31747. However, according to this proposed method, it is necessary to add an extremely large amount of surfactant, which is very costly, and
A large amount of the surfactant is eluted in the manufacturing process, such as a coagulation tank, a desolvation tank, a washing tank, etc., and a large amount of foam is generated, making it difficult to circulate the liquid in the pot and recover the solvent, and to prevent drainage. Problems such as increased dirtiness arise. Further, if the surfactant remains in the product, problems such as inhibiting physical properties such as deterioration resistance and surface strength or causing changes in gloss, color, etc. over time and impairing the appearance arise. Therefore, there are major drawbacks in industrially adopting such proposed methods. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for improving the coagulation properties of hydrophobic polyurethane elastomers which exhibit poor coagulation properties.

Another object of the present invention is to provide a hydrophobic polyurethane elastomer layer with a large number of homogeneous giant structures, which are resistant to deterioration.
It is an object of the present invention to provide a leather-like sheet that is particularly flexible and has excellent hydrolysis resistance, and also has excellent foldability and texture.
The purpose of the present invention is to prepare a hydrophobic polyurethane elastomer solution having a clouding level of 13 or less, water, at least one kind of lower alcohol (referred to as additive 1), and a sulfuric acid ester salt or a sulfonic acid salt. At least one species (
This was achieved by adding additives b) and then wet coagulating. The polyurethane elastomer used in the present invention is a hydrophobic polyurethane elastomer having a cloudiness value of 13 or less. Here, the cloudiness value refers to a polyurethane elastomer solution (solvent dimethylformamide) with a concentration of 5% by weight, kept warm at 5000 for 50 minutes, and dimethylformamide/water 11 minutes with a magnetic stirrer.
This is the amount (cc number) of dimethylformamide/water 1/1 when the polyurethane elastomer solution becomes cloudy when the polyurethane elastomer solution becomes cloudy when the polyurethane elastomer solution is added dropwise little by little with a puree. Cloudiness value 1
Examples of polyurethane elastomers of 3 or less include polyhexamethylene adipate glycol, polycaprolactone glycol, polyalkylene ester glycol, polypropylene glycol, polytetramethylene glycol, and polyurethane containing polyalkylene ether glycol as a soft segment. There is an elastomer, and the chain extender is a diol with 2 to 4 carbon atoms, and the diisocyanate is diphenylmethane-4.4.
′-Diisocyanate is preferred. In particular, the present invention provides a polyurethane elastomer whose soft segment is made of polytetramethylene glycol, which has greatly improved wet coagulation properties and has good quality such as deterioration resistance, appearance, texture, wrinkled moisture permeability, and flexibility. Mar is the best choice. Furthermore, diamine-elongated polyurethane elastomers are also used. The composition of the polyurethane elastomer, that is, the ratio of hard segments to soft segments, influences wet coagulation properties and product quality, and is usually desirably 3 to 6% by weight (N content) based on diisocyanate. In addition, the concentration of polyurethane elastomer can be used in the range of 5 to 35% by weight, but from the viewpoint of operability and product quality, it is less than 10 to 3% by weight.
% by weight is preferred. Additive 1 added to the polyurethane elastomer solution is at least one selected from water and lower alcohols. Examples of lower alcohols include alcohols with a small number of carbon atoms such as methanol, ethanol, propyl alcohol, butanol, etc. In the present invention, the smaller the number of carbon atoms, the greater the effect. Additives 0 added to the polyurethane elastomer solution are sulfuric acid ester salts or sulfones that are soluble in the polyurethane elastomer solvent (e.g. dimethylformamide) or exist as fine particles that are stable in the polyurethane elastomer solution. At least one type selected from acid salts, preferably a soluble one.

Examples of such additives include C8 days, 70 (C2
Day 4) 40S03Na, C9 day, 90 (C2 day 40
)60S03Na C, 2450 (C2 day 40)
30603Na, C, 4 days 290 (C2 ratio ○) 20S0
3NaC 8 days, 70603HN (C2 ratio ○ days) 3, C,
．． Day 230603HN (C2 day 40th) 3 C, 4th day 2
90S03NH (C2 day OH) 3, C8 day, 70 (C2 day OH)
Day 40) 5S03NH (C2 day 40H) 3, C, 2 ratio 5
0 (C2 days 40) 2S03HN (C2 days 40 days) 3, C
, 4 string 90 (C2 day 40) 3S03HN (C2
Day OH)3, C9 day, 90603 day 3NC2 day 40
HC, 4 days 290 S 03 days 3 NC 2 days 40 days
C8 days, 70 (C2 days 40) 3S03 days 3NC2 days 40 days, C,3 is 70 (C2 days ○)6S
03 days 3NC 2 days 40 days, among others, alkyl ether sulfate ester salts, alkylaryl ether sulfate ester salts, alkyl sulfate ester ethanolamine salts,
Particularly preferred are alkylaryl sulfonates and dibasic acid ester sulfonates.

The amount of the coagulation regulator used is preferably in the range of 0.1 to 10% by weight, particularly 0.5 to 8% by weight in the polyurethane elastomer solution. If the amount used is less than 0.1% by weight, there will be no effect, and if the amount is more than 1% by weight, the stability of the polyurethane elastomer solution will deteriorate. Conventionally, in order to use Additive D to control the coagulation of a polyurethane elastomer solution with a cloudiness value of 13 or less, it was necessary to use a very large amount of Additive D, which not only greatly increased the cost, but also required a uniform Although it was often difficult to obtain large pores and surface flatness, in the present invention, by using Additive 1 in combination, this drawback can be greatly improved.

Although water alone is often used in combination, it is often quite effective, but it is even more effective to use water in combination with a water-soluble lower alcohol such as methanol or ethanol. The amount of the additive 1 used is 0.00% of the polyurethane elastomer solution.
It is preferable to add a very small amount of 1 to 8% by weight, particularly 0.5 to 5% by weight. Addition of a large amount is not preferable because the polyurethane elastomer solution becomes cloudy or gelatinized, resulting in lack of stability. Further, if the amount is extremely less than 0.1% by weight, sufficient effects cannot be obtained. Furthermore, in the present invention, the m-th
It has been confirmed that adding titanium oxide as an additive to the polyurethane elastomer in an amount of 0.1 to 2% by weight, preferably 0.5 to 1% by weight is more effective.

The present invention is achieved by dissolving the above-mentioned specific polyurethane elastomer in an organic solvent, preparing a composition solution containing additives 1 to 0, and optionally m, and performing wet coagulation using the composition solution. A porous film can be made by coating this liquid composition on a support and removing the support after solidification. A base fabric for a leather-like sheet can also be produced by impregnating and/or coating a base material and solidifying it. Note that the additives can also be removed by washing with water or other steps if necessary. When producing a leather-like sheet using a fibrous base material in the present invention, conventionally known materials suitable for producing a leather-like sheet can be used as they are, but in order to fully utilize the features of the present invention, It is better to choose a special flexible fibrous material.

This is because the porous sheet with relatively uniform large pores obtained in the present invention is sufficiently flexible and durable compared to conventional porous sheets, so selection is important as a fibrous material. be. Such special flexible and durable fibrous materials are also known, such as porous array fibers made by removing at least one component of mixed spun fibers, ultrafine fibers, and 2
Fibers such as 5 or more ultrafine fibers of 0.5 denier or less can be obtained by making composite fibers from polymers of different types and treating them with solvent to extract one component, or by splitting them. be. Specific applications of these can be found, for example, in Japanese Patent Publication No. 41-375.
No. 9, Special Publication No. 46-41235, Hakama Publication No. 52-289
No. 18 and Japanese Patent Publication No. 52-30629.
The polyurethane elastomer solution may contain stabilizers, fillers, pigments, dyes, etc., as well as polymers with good compatibility in the solution state, such as polyvinyl chloride, polyvinyl acetate, polyvinyl formal, and methacrylic acid resin, as necessary. , vinylidene chloride-acrylonitrile copolymer, and vinyl chloride-vinyl acetate copolymer.

As mentioned above, the polyurethane elastomer solution can be used for either the binder or the coating layer of the fibrous material, but the latter is more effective.

In the case of leather-like sheets with a porous covering layer, the covering layer should therefore necessarily be made from the polyurethane elastomer solution. In the present invention, uniform large pores are created within a single layer of the polyurethane elastomer, and wet coagulation is preferably performed at a relatively high non-solvent concentration and low temperature.

The leather-like sheet obtained as described above is finally subjected to finishing treatments such as softening agent treatment, buffing, coloring, embossing or fir processing.

The present invention will be specifically described below with reference to Examples.

All percentages in this example are by weight. Example 1
Polyurethane elastomer synthesized from polytetramethylene glycol, ethylene glycol and diphenylmethane-4,4'-diisocyanate (N content 5%, cloudiness value 4) 15%, carbon black 0.5%, C, 2-day-old OS03HN A solution consisting of 32% (C2 day OH), 3.5% water and 79% dimethylformamide was soaked in a non-woven fabric of nylon fibers, and the solid content was poured on top of this for 90 minutes/day.
After coating it to make it strong, it was coagulated for 3 seconds with a 40 oz aqueous solution containing 40% dimethylformamide.
A leather-like sheet [A] was produced by removing the solvent with 60 to 70 q○ hot water for 2 hours and then drying.

This product had many uniform giant pores in both the fibrous base and the coating layer, and the surface flatness was also very good. - way,
In the above polyurethane elastomer solution, a polyurethane elastomer solution in which only water or C, 250S03HN (C2day 40H) 3 or water and C, 2 ratio 50603HN (C2day 40H) 3 was removed was added. Leather-like sheets [B], [C] and [D] were produced from this solution and a nonwoven fabric of nylon fibers in the same manner as described above.

Compared to the leather-like sheet [A], both the fibrous substrate and the coating layer had a smaller number of giant pores, were non-uniform, and had poor surface flatness. The above leather-like sheets [A], [
B], [C] and [D] contain 6% of the same polyurethane elastomer as above, 3% of carbon black, 21% of dimethylformamide, 35% of acetone and 35% of cyclohexane.
% and the same solution as above, consisting of 7% polyurethane elastomer, 23% dimethylformamide, 35% acetone, and 35% cyclohexanone, each in solid content, was applied by gravure method for 3 days/day, dried, and then dried. After stamping the fabric pattern, fir processing was performed.

The results of these evaluations are shown in Table 1, as shown in Table 1.
A] had extremely good not only flatness but also folding, texture, moisture permeability, etc. Furthermore, when men's shoes were made and worn using this product, no abnormalities such as cracking were observed even after one year, and the product value was high. On the other hand, leather-like sheet [B]
, [C], and [D] were all very inferior in appearance and quality to the leather-like sheet [A], and had low commercial value. Table 1 [Note] Moisture permeability JISK-6549: g/〆day Example 2 Polyethylene propylene adipate glycol, 1
・4-Butanediol and diphenylmethane-4,4-
A solution consisting of 15% polyurethane elastomer (white turbidity value 18) with an N content of 4.0% synthesized from diisocyanate, 0.5% carbon black, 1.2% stearyl alcohol, and 833% dimethylformamide was mixed with nylon and polystyrene. Mixed grade yarn fibers (mixing ratio 1:1) mixed into a non-woven fabric containing 50% dimethylformamide 40
After coagulating with an aqueous solution of qC for 30 minutes, the polystyrene was extracted and removed with hot toluene, the solvent was removed with hot water, and the mixture was dried to produce a fibrous substrate.

Separately, a polyurethane elastomer with an N content of 4.5% synthesized from polypropylene glycol, 1,4-butanediol and diphenylmethane-4,4-disocyanate (white turbidity value 12), 15%, carbon black 0.5%,
%, water 0.5%, methanol 0.5%, and dimethylformamide 79.5% and the same polyurethane elastomer solution as above were separately coated on a polyethylene sheet at a solid content of 80 ml per day. The films were coagulated for 30 minutes in a 30qo aqueous solution containing 40% dimethylformamide, peeled off from the support, and stearyl alcohol was extracted with methanol and dried to form porous films (E) and ( F) was produced.

All of these had many uniform giant pores and had good surface flatness. These porous sheets and the aforementioned fibrous substrate whose surface had been smoothed by buffing were adhered to obtain leather-like sheets [E] and [F], respectively.

Finally, to these, 5% polyurethane elastomer synthesized from polyethylene glycol, ethanolamine and diphenylmethane-4,4'-diisocyanate, 2% methacrylic acid resin, lr sharklanBlackGBL (C
i Mother Snake (Igy) 2%, dimethylformamide 21%
, a solution consisting of 36% acetone and 34% cyclohexanone was coated as solids for 3.5 days, and after drying, a hair shark pattern was embossed. All of these products had good flatness, texture, foldability, moisture permeability, etc. When men's shoes were made and worn using these materials, no abnormalities were observed in the shoes using the leather-like sheet [E] even after one year, but the shoes using the leather-like sheet [F] only lasted for two weeks. After some time, severe cracking occurred. Example 3 Polyurethane elastomer with an N content of 4.3% synthesized from polycaprolactone glycol, ethylene glycol and diphenylmethane-4,4'-diisocyanate
(White cloudiness value 9) 11%, polyvinyl chloride 2% 1.5%, methanol 25% and dimethylacetamide 83%
A solution consisting of polyethylene and nylon.

Claims (1)

[Claims] 1. When a porous sheet is produced by coagulating a hydrophobic polyurethane elastomer solution having a cloudiness value of 13 or less, at least one kind selected from water and lower alcohols (additives) is used as the polyurethane elastomer solution. I) and at least one selected from sulfate ester salts or sulfonate salts.
A method for producing a flexible porous sheet, characterized by using a composition liquid containing seeds (additive II). 2. The manufacturing method according to claim 1, wherein the additive II is a sulfate salt or a sulfonate salt soluble in the solvent of the polyurethane elastomer. 3. The manufacturing method according to claim 2, wherein the polyurethane elastomer is synthesized from polytetramethylene glycol, diphenylmethane-4,4'-diisocyanate, and a glycol having 2 to 4 carbon atoms. 4. The manufacturing method according to claim 1, wherein titanium oxide is added to the polyurethane elastomer solution. 5 Claim 1 or 4 in which additive I is water
Manufacturing method described in section. 6. The manufacturing method according to claim 1 or 4, wherein additive I is a combination of water and lower alcohol. 7. The method for producing a leather-like sheet according to claim 1, wherein the sulfate ester salt is an alkyl sulfate ethanolamine salt. 8. The method for producing a leather-like sheet according to claim 1, wherein the sulfate ester salt is an alkyl ether sulfate ethanolamine salt. 9. The method for producing a leather sheet according to claim 1, wherein the sulfate ester salt is an alkylaryl ether sulfate ethanolamine salt. 10. The method for producing a leather-like sheet according to claim 1, wherein the sulfate ester salt is an alkyl ether sulfate Na salt. 11. The method for producing a leather-like sheet according to claim 1, wherein the sulfate ester salt is an alkylaryl ether sulfate Na salt. 12 Sulfonate is Na alkylarylsulfonate
A method for producing a leather-like sheet according to claim 1, which is a salt. 13. The method for producing a leather-like sheet according to claim 1, wherein the sulfonate is an ester sulfonic acid Na salt. 14 Sulfonate is dibasic acid ester sulfonate Na
A method for producing a leather-like sheet according to claim 1, which is a salt.