JPH02147662A - Polyurethane solution composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which can form an air-permeable polyurethane layer in which fine pores are uniformly distributed irrespectively of a small change in process conditions, etc., by mixing a polyurethane solution with water and a specified thermoplastic resin. CONSTITUTION:A polyurethane solution (a) is obtained by reacting a long-chain glycol with an organic isocyanate and a low-molecular diol in an organic solvent of a b.p. <=120 deg.C and a solubility in water at 20 deg.C of 1-50g/100g. Component (a) is mixed with 10-95%, based on the critical water content, water (b) and 0.1-30wt.%, based on the polyurethane of component (a), thermoplastic resin (c) which is soluble in component (a) and can be deposited before the polyurethane does when the solvent is removed from component (a) (e.g. a copolymer of PVC with a polyurethane in a weight ratio of 70-40/30-60).

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention involves applying or impregnating a fiber aggregate sheet made of a release sheet, a nonwoven fabric, a fabric, or a laminate thereof, and then solidifying and drying polyurethane. By this, a breathable porous polyurethane layer is formed on the release sheet or fiber aggregate sheet, and it is peeled off from the release sheet to obtain a polyurethane film, or it can be used to create artificial leather or other materials having a polyurethane layer on the surface of the fiber aggregate sheet. The present invention relates to a polyurethane solution composition used to obtain an artificial leather substrate having a polyurethane layer between the fibers of a fiber aggregate sheet.

(Prior art) A polyurethane solution is obtained by reacting long-chain glycol 1 organic isocyanate, low-molecular diol, etc. with an average molecular weight of 500 to 5000 in an organic solvent, and water is added to the solution to form a water-in-oil type (W2O type). ) is made into a water-containing slurry, the slurry is applied or impregnated onto a release sheet or fiber aggregate sheet, and then dried to form a breathable porous polyurethane layer on the release sheet or fiber aggregate sheet. This method uses methyl ethyl ketone (ME) in an organic solvent.
) with a boiling point lower than water,
Drying is performed in two stages: at a temperature above the boiling point of the solvent but below the boiling point of water, and at a temperature above the boiling point of water, and the organic solvent is evaporated first and then the water is evaporated. There is a problem in that it is difficult to form a breathable polyurethane layer in the structure. Furthermore, if the water distribution in the water-containing slurry is not uniform, it will be difficult to form a polyurethane layer with a uniform porous structure.
Due to fluctuations in process conditions, the water distribution becomes uneven and the surface layer of the polyurethane layer becomes porous. There is also the problem that the physical properties of the polyurethane layer become poor, resulting in a lower yield especially when producing polyurethane films and artificial leather.

[Problem to be solved by the invention]

The present invention has been made with the aim of solving the above-mentioned problems, and when solidifying and drying polyurethane using the dry method described above, even if the drying is performed in one step at a temperature higher than the boiling point of water, or the interface A polyurethane type 10 water-containing slurry that can form an air-permeable polyurethane layer with uniformly distributed fine pores even if no or little activator is used or there are slight variations in process conditions, etc. The purpose is to provide an 8-liquid composition.

[Means to solve the problem]

The present inventor has developed a polyurethane W that can stably form a porous, breathable polyurethane layer with excellent physical properties using a dry method.
As a result of repeated research on Type 10 water-containing slurry, we found that thermoplastic resins that solidify and precipitate earlier than polyurethane when dissolved in water-containing slurry and desolventized to remove the organic solvent from the water-containing slurry were found to 30% by weight
By adding and mixing, you can avoid using a lot of W surfactant.
It has been found that even when drying is performed at one temperature step, it is possible to stably form a breathable polyurethane layer in which fine pores are uniformly distributed.

The present invention was made based on this knowledge, and the solubility of water at 20''C is 100°C when the boiling point is 120°C or lower.
Add at least 10 to 95% of the critical water amount to a polyurethane solution obtained by reacting long chain glycols, F-functional isocyanates, low molecular diols, etc. in an organic solvent of 1 to 50 g per gram; A polyurethane solution characterized in that a thermoplastic resin is added and mixed in an amount of 0.1 to 30% by weight of the polyurethane, which is assimilated and precipitated before the polyurethane when the organic solvent is removed from the solution. In the composition.

[For production]

In the polyurethane solution composition of the present invention, when the solvent is removed by evaporation of the organic solvent or the like, the thermoplastic resin solidifies and precipitates before the polyurethane solidifies, which becomes a core and creates micropores in the polyurethane layer. Therefore, even if the water distribution in the polyurethane solution composition becomes somewhat uneven, the drying process can be
Even if it is carried out in stages, it is possible to form a breathable polyurethane layer in which fine pores are uniformly distributed. It is also possible to remove the solvent by a wet method using water to solidify the thermoplastic resin and polyurethane before drying, whereby a porous polyurethane layer with excellent air permeability is formed.

Regarding the present invention, if the boiling point of the organic solvent is higher than 120° C., water will evaporate first when the solvent is removed in a dry manner, resulting in a polyurethane layer with poor air permeability.

The boiling point of the organic solvent is preferably lower than the boiling point of water, similar to the conventional polyurethane-10 type water-containing slurry, and the solubility of water at 20°C of the organic solvent is 1 g per 100 g.
If it is smaller, the polyurethane layer will have poor air permeability, and if the water solubility exceeds 50 g per 100 g, the solvent and water will easily evaporate together when removing the solvent by evaporation, so # If less than 1q is not evaporated, the polyurethane layer tends to have a rough structure and poor physical properties, and it is also difficult to remove the solvent by a wet method.

The amount of water added is the critical water amount, that is, 10% of the critical water concentration at which water will not dissolve or disperse uniformly as water is added.
If it is less than 95%, the breathability of the polyurethane layer decreases and
%, the polyurethane layer tends to have a rough porous structure with poor physical properties.

In addition, the amount of thermoplastic resin added is 0.1 of that of polyurethane.
If it is less than 30% by weight, it will not be different from the conventional polyurethane W10 type water-containing slurry, and if it is more than 30 parts, the physical properties of the polyurethane layer will be deteriorated by the thermoplastic resin.6 For the above reasons, the polyurethane solution composition of the present invention The reason why micropores are formed with the solidified and precipitated thermoplastic resin as the core is that water collects around the solidified and precipitated thermoplastic resin, and after the polyurethane begins to solidify, water evaporates and forms around the thermoplastic resin. The first is to create voids in the thermoplastic resin, and the second is that the solidified polyurethane shrinks and creates voids around the thermoplastic resin.
It can be considered.

(Example) As an organic solvent in the present invention, a boiling point of 120°C or less, preferably 100°C or less, and a water solubility at 20°C, such as those used in conventionally known solution polymerization or slurry polymerization of polyurethane, are used. 1-5 per 100g
0g of organic solvent can be used, e.g. lEK
, methyl isobutyl ketone (MIBK).

Preferred examples include methyl butyl getone (MB), tetrahydrofuran (THF), and acetone.

Also, long chain glycols reacted in organic solvents.

As the organic isocyanate and low-molecular diol, long-chain glycols, organic isocyanates, and low-molecular diols having an average molecular weight of 500 to 5,000, which are conventionally used in solution polymerization or slurry polymerization, can be used. That is, long-chain glycols include polyalkylene ether diols such as polyethylene ether glycol, polypropylene ether glycol, and polytetramethylene ether glycol, and polyester diols such as polyethylene adipate, polyethylene adipate, and polyhexamethylene adipate, and diphenylmethane-4 and diphenylmethane-4 as organic isocyanates. 4'-diisocyanate, tolylene-
2,4-diisocyanate, phenylene diisocyanate, xylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, hexamethylene diisocyanate, etc., and low molecular weight diols such as ethylene glycol, 1,4-butanediol, cyclohexane-1,
4-diol α・α′-p-xylene diol, 1・
4-bis(β-hydroxyethoxy)benzene, 2.2
-bis(4-(β-hydroxyethoxy)phenyl)propane, propylene diamine, hexamethylene diamine, and the like.

Furthermore, the polyurethane production reaction in an organic solvent can be carried out in the same manner as conventionally known solution polymerization or slurry polymerization, and can be carried out using surfactants, colorants, antistatic agents, H fuels, stabilizers against heat and light, etc. It is also possible to add additives and to appropriately adjust the viscosity of the resulting polyurethane solution by adjusting the concentration of polyurethane, etc., in the same manner as in conventional methods. In addition, it is preferable to add a surfactant after or before the reaction in order to obtain a polyurethane solution with a large amount of critical water, but if the polyurethane to be produced has a hydrophilic group in its main chain, it is not necessary to add It is not necessary to do so.

As the thermoplastic resin that dissolves in a polyurethane solution and solidifies and precipitates earlier than polyurethane, a vinyl chloride/urethane copolymer or a cellulose derivative is preferably used, or an acrylonitrile/styrene copolymer or the like is also used. Examples of vinyl chloride/urethane copolymers include polyvinyl chloride (PI/C) and polyurethane 7 (PHI).
Examples of cellulose derivatives include cellulose acetate, cellulose butyrate, cellulose propionate, and the like. The addition of 0.1 to 30% by weight of such a thermoplastic resin to the polyurethane is not limited to after the polyurethane production reaction, but may be added before the reaction.

The polyurethane solution composition of the present invention obtained as described above has the same characteristics as the conventional polyurethane-10 type water-containing slurry.
It can be applied or impregnated onto a release sheet or fiber aggregate sheet, and the added thermoplastic resin and polyurethane are solidified by removing the solvent using a dry or wet method, and then dried to form a thermoplastic resin. A large number of uniformly distributed core micropores forms a breathable polyurethane layer with excellent physical properties, making it possible to produce breathable porous polyurethane films and artificial leather with high yields.

Hereinafter, further specific examples of the present invention will be shown. In addition, parts in the examples represent parts by weight.

Example 1 Polytetramethylene glycol (min 1121.90) 3
00 parts, polycaprolactone diol (molecular weight 1810
) 296 parts of diethylene glycol, 30 parts of diethylene glycol, and 315 parts of diphenyl 4,4' diisocyanate were dissolved in 235 parts of methyl ethyl ketone, and 0.2 parts of triethylene diamine was added and the mixture was reacted at 60°C for 90 minutes. Add 710 parts of a 9/1 mixed solvent, then further add 60 parts of tetramethylene glycol, stir while controlling the temperature at 65-70"C, and as the viscosity increases, the methyl ethyl ketone/toluene mixing ratio becomes 9.
A polyurethane solution with a viscosity of 1,800 cps/70° C./20 weight percent polyurethane was obtained by pouring a mixed solvent of 1/1 and reacting for about 4 hours. Modified polyalkylene oxide obtained by adding polypropylene oxide to dimethylpolysiloxane having an average molecular weight of 3400 and having two hydroxyl groups at the terminals under a caustic alkali catalyst, and then adding polyethylene oxide to 100 parts of this solution. After adding the surfactant consisting of polysiloxane, 28 parts of water and PVC/PU were mixed with a homomixer while stirring.
5 parts of vinyl chloride/urethane copolymer in a 60/40 ratio were added.

The obtained polyurethane solution composition was applied onto a release sheet and dried in IOO'C, and then the release sheet was separated to obtain a polyurethane film having a basis weight of about 30 g/ii''.

This polyurethane film has relatively large pores distributed inside it, but between the pores and on the surface, vinyl chloride/
A large number of micropores centered on the urethane copolymer were uniformly distributed, resulting in excellent air permeability and physical properties, as well as excellent surface uniformity. On the other hand, when the vinyl chloride/urethane copolymer was not added, the resulting polyurethane film had poor air permeability even though a coarse pore distribution was observed.

Example 2 A polyurethane film was obtained under the same conditions as in Example 1 except that cellulose acetate was used instead of the vinyl chloride/urethane copolymer. Like the polyurethane film of Example 1, this polyurethane film was also excellent in air permeability and physical properties, and had excellent surface uniformity.

〔Effect of the invention〕

The polyurethane solution composition of the present invention can stably form a breathable polyurethane layer with excellent physical properties in which micropores are uniformly distributed on the surface and inside, and solidification of polyurethane can be performed by either a dry method or a wet method. It has the effect that it can also be done by

Claims (1)

[Claims] The boiling point is below 120℃ and the solubility of water at 20℃ is 10
A solution of polyurethane obtained by reacting long-chain glycols, organic isocyanates, low-molecular diols, etc. in an organic solvent of 1 to 50 g per 0 g, and at least 10 to 95% of the critical water amount dissolved in the solution. A polyurethane solution composition characterized in that a thermoplastic resin is added and mixed in an amount of 0.1 to 30% by weight of the polyurethane, which solidifies and precipitates before the polyurethane when the organic solvent is removed from the solution. thing.