JPS60252638A - Preparation of porous sheet material - Google Patents

Abstract

PURPOSE:To obtain a porous sheet material having improved mechanical properties, permeability to water vapor, economic efficiency, etc., by applying or impregnating an emulsion consisting of a specific hydrophobic polyurethane, a specified hydrophilic polyurethane, an organic solvent, and water into a substrate, followed by drying it. CONSTITUTION:(A) A hydrophobic polyurethane polymer obtained by reacting A1: a hydrophobic high polymer diol having 500-4,000 average molecular weight with A2: an organic diisocyanate and A3: a chain extender comprising a compound having >=300mol.wt. and two functional active hydrogen-containing groups is blended with (B) a hydrophilic polyurethane polymer shown by the formula (R is prepolymer having hydrophobic isocyanate end; E is A3 part; G is B1 part; n is 1-3) obtained by reacting A1 with A2 in a ratio of NCO/OH of 1.5-2.5 to give a prepolymer having a hydrophobic isocyanate end, reacting the prepolymer with A3, and then B1: polyoxyethylene glycol, (C) an organic solvent having 1- 50g water solubility at 20 deg.C and 50-120 deg.C boiling point at normal pressure, and (D) water, and the prepared emulsion is applied to or impregnated into the substrate.

Description

[Detailed description of the invention] industrial application field] The present invention relates to a method for manufacturing porous sheet materials.

[Prior art]

Conventionally, methods for obtaining porous sheet materials from polyurethane polymer solutions as substitutes for natural leather, etc. can be broadly classified into wet methods and dry methods. In the wet method, a large amount of equipment is required to remove the solvent from the polyurethane polymer solution by treating it with a liquid that is miscible with the solvent but inert to the polymer. In addition, it takes a long time to completely extract the solvent, resulting in poor productivity and high product costs.

On the other hand, as a method for making porous sheet materials using a dry method,
The main conventionally known examples include (1) adding a bubble-generating substance (ammonium carbonate or azobisisobutylnitrile, etc.) to a polymer solution, volatilizing the solvent to form a film, and then heating it. A method of obtaining a porous sheet material by foaming, (2) creating a water-in-oil emulsion of a polymer, coating or impregnating it on a substrate, and in one drying step, first evaporating the solvent in the emulsion and then evaporating the water. There is a method of obtaining a porous sheet material by this method. Method (1) has good productivity, but has the disadvantage that undesirable gas is generated due to the decomposition of the blowing agent, and when it is made into a sheet material, it tends to become closed cells due to large pores, making it impossible to obtain sufficient physical properties. . Method (2) includes, for example, Japanese Patent Publication No. 55-18249,
There is a method described in Japanese Patent No. 8579. Although this method allows a relatively homogeneous porous sheet material to be obtained, the manufacturing method requires a complicated and time-consuming drying process, which impairs productivity. The disadvantage is that

[Purpose of the invention]

With the aim of more economically producing porous sheet materials with excellent mechanical properties, water vapor permeability, etc., we have conducted extensive research to improve the shortcomings of the dry method.
The present invention was developed based on the discovery that a finely homogeneous porous sheet material for noodles that is economical and extremely high in quality can be obtained.

[Structure of the invention]

That is, the present invention provides a method for producing a porous sheet material in which a substrate is coated with or impregnated with a polyurethane emulsion consisting of a hydrophobic polyurethane polymer, a hydrophilic polyurethane polymer, an organic solvent, and water, and is then dried. Hydrophilic polyurethane polymer (B) represented by the following general formula (1), G→B-E-iR-G (1 ) However, R: Hydrophobic isocyanate-terminated prepolymer portion E: Chain extender portion G: Polyoxyethylene glycol portion n: A positive number from 1 to 3 An organic solvent (C) that has limited mutual solubility with water; This is a method for producing a porous sheet material characterized by using a polyurethane emulsion consisting of the following.

The hydrophobic polyurethane polymer (A) itself used in the present invention is composed of known materials, including (1) a hydrophobic polymeric diol having an average molecular weight of 500 to 4,000 and having hydroxyl groups at both ends; 2) Organic diisocyanate% (3) Polyurethane obtained by reacting with a chain extender. The polymer diol in (1) is polyalkylene ether glycol or glycol such as polypropylene ether glycol or polytetramethylene ether glycol. Linear polymers such as polyester glycols such as polyethylene adipate, polybutylene adipate, polypropylene adipate, and polyethylene butylene adipate, or poly-ε-caprolactone glycol, which have hydroxyl groups at both ends obtained by the reaction of dicarboxylic acid and can be used in combination. (2)
Examples of organic diisocyanates include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4- and 2,6-dolylene diisocyanate, and aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate or methylene bis(4-cyclohexyl). isocyanate), isophorone diisocyanate, and other alicyclic diisocyanates are used. (3) As chain extenders, compounds containing bifunctional active hydrogen-containing groups (hydroxyl group, amino group, etc.) with a molecular weight of 300 or less, such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6- Dionyl such as hexanediol; diamines such as ethylene diamine, propylene diamine, hexamethylene diamine, and isophorone diamine can be used.

The reaction conditions can be synthesized by conventionally known methods, preferably in an organic solvent (C1).

Hydrophilic polyurethane polymer used in the present invention (
B) is characterized by its structure, and only when it has the structure represented by general formula (1) can the desired homogeneous porous sheet material be obtained. More specifically, it has a structure represented by the following general formula (2).

-OH (2) However, R/: hydrophobic isocyanate-terminated prepolymer residue.

E': Chain extender residue.

G': polyoxyethylene glycol residue.

X: O, NH, etc. (active hydrogen-containing group -XH with active hydrogen atom removed) n: Positive number from 1 to 8.

The above polymer (B) is produced by preparing a hydrophobic isocyanate-terminated prepolymer (0ON-r -NCO) from (1) a hydrophobic polymeric diol and an excess amount of (2) an organic diisocyanate, and then adding this to (3) a chain. Extender (HX-E'-X
H) and further reacted with (4) polyoxyethylene glycotyl (HO-G'-0H).

(1) Hydrophobic polymeric diol, -(2) Organic diisocyanate, (3) As the chain extender, the same materials as those for the hydrophobic polyurethane polymer (5) can be used, and (4) As polyoxyethylene glycol, is the average molecular weight of 1000
~8000 is preferred. When preparing a hydrophobic prepolymer, the ratio of hydrophobic polymer diol to organic diisocyanate is such that the N0O10H ratio is usually 1.5 to 2.5, preferably 1.8 to 2.0. The molar ratio of hydrophobic prepolymer to chain extender is usually from 2:1 to 4:8. The amount of polyoxyethylene glycol is usually 1.8 to 2.2 mol, preferably 2 mol, per mol of chain-extended prepolymer. [In addition, if the amount is 1.8 mol to less than 2 mol, a small amount of monomers with structures represented by general formulas (1) and (2) and those further extended with polyoxyethylene glycol will be produced. , such substances are also included in the polymer (B) in the present invention. ] Also, it is preferable that the polyoxyethylene chain in the hydrophilic polyurethane polymer (B) is 42 to 60% by weight.

By the above method, a polyurethane polymer (B) having polyoxyethylene chains at both ends represented by the general formula (1) can be obtained. At this time, it is preferable to synthesize in an organic solvent (q). If a chain extender is not used or is used in an amount exceeding the conditions, it is difficult to obtain the porous sheet material that is the object of the present invention. Can not.

The organic solvent used in the present invention has a limited mutual solubility with water (the solubility of water is 1 to 50 g at 20°C, preferably 2 to 80 g (per 100 I of the organic solvent)), and the boiling point is at normal pressure. For example, ketone solvents such as methyl ethyl ketone (hereinafter abbreviated as MEK), methyl isobutyl ketone, methyl-n-propyl ketone, ethyl formate, propyl formate,
Ester solvents such as methyl acetate and ethyl acetate are preferred. However, acetone, tetrahydrofuran, dioxane,
It is also possible to use water-miscible solvents such as methanol, ethanol, propatool, etc. or water-immiscible solvents such as toluene and xylene in combination with organic solvents that have limited mutual solubility with water.

The product obtained by polymerizing the hydrophobic polyurethane polymer (inside) in an organic solvent (C) is an opaque dispersion;
'are doing. On the other hand, the hydrophilic polyurethane polymer (B) can be obtained as a solution in an organic solvent (q).

In order to obtain the polyurethane emulsion used in the present invention, first, a hydrophobic polyurethane polymer dispersion and a hydrophilic polyurethane polymer (3) solution are mixed. At this time, preferably the solid content weight ratio of the polymer (gradient: polymer (to) = 80 to
The ratio of solid content to organic solvent in the resulting mixture is preferably 98:20 to 2, and the ratio by weight of solid content to organic solvent is preferably 30 to 10 (nearly 0 to 90). Next, water is added to this mixture while stirring it with a homomixer to obtain a polyurethane emulsion. The amount of water to be added is 50 to 50 parts by weight of solid content of the polymer mixture.
The amount is 500 parts by weight, preferably 100 to 400 parts by weight.

In this case, a stable emulsion cannot be obtained unless the hydrophilic polyurethane polymer (B) is used.

In the method of the present invention, auxiliary compounding agents may be used in combination, if necessary. For example, dyes for decorative coloring,
Coloring agents such as pigments, inorganic fillers such as calcium carbonate and glass fiber, organic modifiers such as AS resin and PYO resin, various stabilizers and 1 softeners and plasticizers to improve heat resistance (light resistance) and deterioration resistance. etc. can be used. Various substrates to which the method of the present invention is applied can be used, such as one knitted fabric, one woven fabric, one nonwoven fabric, one glass plate, a metal plate, and one paper and one plastic film.

〔Effect of the invention〕

A very short drying step (in order to obtain porous sheet materials from the polyurethane emulsions obtained by the process of the invention) is sufficient. For example, after applying the emulsion to the substrate and impregnating it, heat the emulsion in a circulating air dryer at 50 to 100°C.
×1 to 5 minutes, further at 100 to 150°C as necessary
*You only need to dry it for 1 to 5 minutes. In other words, the special public service in 1977-
No. 18249 and Japanese Patent Publication No. 58-48579, complicated steps such as pre-treatment steps are completely unnecessary. It is also possible to use a substrate that cannot be heated, and in this case, a porous sheet material can be obtained simply by air drying at room temperature.

The porous sheet material thus obtained can be used as a substitute for leather (shoes), bags, furniture, clothing, paints, floors, etc.
It can be used for building materials such as walls, air filters, and furnace materials.

〔Example〕

The present invention will be explained below with reference to Examples. The following parts and h indicate parts by weight and % by weight, respectively. 'Each polymer used in Examples and Comparative Examples was produced as follows.

Polymer (A-1): 200 parts of polytetramethylene glycol with an average molecular weight of 2000 and 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MLII 9100)
Pour into a part number polymerization vessel and stir in a nitrogen gas atmosphere for 60 minutes.
After reacting for 0.2 hours, 186 parts of MEK 743 ethylene glycol and 0 parts of dibutyltin dilaurate were added.
．． 02 parts were added and the reaction was continued at 70°C for about 6 hours. Cool to room temperature with stirring to obtain a cloudy white polymer (with a concentration of 30% and a viscosity of 12,000 cps/20"Q).
A dispersion of A-1) was obtained.

Polymer (A-2): 250 parts of polybutylene adipate diol with an average molecular weight of 2500 and 100 parts of MDI were charged into a polymerization vessel, and 70" Os
After reacting for 2 hours, 860 parts of MEK, 186 parts of ethylene glycol, and 0.02 parts of dibutyltin dilaurate were added.
of the mixture was added, and the reaction was continued at 70°C for about 6 hours. Cool to room temperature while stirring until the concentration is 30% and the viscosity is 18%.
,000 cps 720℃ cloudy polymer (A-2
) was obtained.

Polymer (A-8): 100 parts of poly ε mucabrolactone diol with an average molecular weight of 2000, average molecular weight zioo.

50 parts of polyoxypropylene glycol and MDI
After charging 87.5 parts into a polymerization vessel and reacting with stirring in a nitrogen gas atmosphere at 70°C for 2 hours, MEK 607
22.5 parts of 1,4-butanediol and 0.02 parts of dibutyltin dilaurate were added, and the mixture was further heated at 70°C for about 6 parts.
The reaction continued for hours. The mixture was cooled to room temperature with stirring to obtain a cloudy white dispersion with a concentration of 80% and a viscosity of 10.000 cps/20'O.

Polymer (B=1): 800 parts of polytetramethylene glycol with an average molecular weight of 1000 and 150 parts of MDI were charged into a polymerization vessel, and 70'
After reacting for 2 hours with 862 parts of MEK, ethylenezo! J: 'Jl/12.4 parts and 0.02 parts of dibutyltin dilaurate are added. After continuing the reaction at 70"C for 8 hours, 400 parts of polyoxyethylene glycol having an average molecular weight of 2000 was further added, and the reaction was continued at 70"C for 5 hours.

Cool to room temperature while stirring, and add a polymer with a concentration of 5Q% (
A solution of B-1) was obtained. The proportion of polyoxyethylene groups in the solid content is 46.

Polymer (B-2): Instead of the polytetramethylene glycol used in (B-1), 150 parts of polyoxypropylene glycol with an average molecular weight of 1000 and 150 parts of polybutylene adipate diol with an average molecular weight of 1000 are mixed and used. The reaction was carried out in the same manner as in (B-1) to obtain a solution of polymer (B-2) at a concentration of 50%.

Polymer (B-8): 200 parts of polytetramethylene glycol with an average molecular weight of 1000 and 100 parts of MDI were charged into a polymerization vessel, and the reaction was carried out in the same manner as in (B-1) ~ MEK
The reaction was continued by adding 709 parts of 1,4-butanediol, 9 parts of diptyltin dilaurate, and 400 parts of polyoxyethylene glycol having an average molecular weight of 2,000. E-
A solution of 8) was obtained. The proportion of polyoxyethylene groups in the solid content of this solution was 56.

Polymer (B-4): 800 parts of polytetramethylene glycol with an average molecular weight of 1000 and 150 parts of MDI were charged into a polymerization vessel, and the reaction was carried out in the same manner as in (B-1)) ME
Continue the reaction by adding 1062 parts of K to 12.4 parts of ethylene glycol and 0.02 parts of diptyltin dilaurate 1 Further, continue the reaction by adding 600 parts of polyoxyethylene glycol with an average molecular weight of 3000 1 Polymer with a concentration of 50% A solution of (B-4) was obtained. The proportion of polyoxyethylene groups in the solid content of this solution is 56.

Polymer (B-5): 400 parts of polytetramethylene glycol with an average molecular weight of 2000 and MDI 100%f
Charge f5 into a polymerization vessel and carry out the reaction in the same manner as (B-1).
, 906 parts of -MEK, 6.2 parts of ethylene glycol and 002 parts of dibutyltin dilaurate were added to continue the reaction, and 40 parts of polyoxyethylene glycol having an average molecular weight of 2,000 was further added to continue the reaction. A solution of polymer (B-5) was obtained. The proportion of polyoxyethylene groups in the solid content of this solution was 44.

Polymer (B-6): 300 parts of polytetramethylene glycol with an average molecular weight of 1000 and 15'7 parts of methylene bis(4-cyclohexyl isocyanate) were charged into a polymerization vessel, and heated at 110°C under stirring in a nitrogen gas atmosphere for 2 hours. After reacting for an hour, 870 parts of MEK, 12.4 parts of ethylene glycol and 0.02 parts of dibutyltin dilaurate are added. After continuing the reaction at 70°C for 5 hours, polyoxyethylene glycol 10 with an average molecular weight of 2000 was added to each sample.
of the mixture was added, and the reaction was continued at 70°C for 8 hours.

Cool to room temperature while stirring, and add a polymer (B) with a concentration of 50%.
-6) solution was obtained. The proportion of polyoxyethylene groups in the solid content of this solution was 46%.

Polymer (b-7): 800 parts of polytetramethylene glycol with an average molecular weight of 1000 and 150 parts of MDI were charged into a polymerization vessel, and the reaction was carried out in the same manner as in (B-1).
The reaction was continued by adding 582 parts of K, 124 parts of ethylene glycol, and 0.02 parts of diptyltin dilaurate, and further the reaction was continued by adding 120 parts of polyoxyethylene glycol having an average molecular weight of 600.
-7) solution was obtained. The proportion of polyoxyethylene groups in the solid content of this solution was 21%.

Polymer (b-8): 500 parts of polytetramethylene glycol with an average molecular weight of 1000 and 250 parts of MDI were charged into a polymerization vessel, and the reaction was carried out in the same manner as in (B-1).
1175 parts, 24.8 parts of ethylene glycol, and 0.02 parts of diptyltin dilaurate were added to continue the reaction.
Furthermore, 400 parts of polyoxyethylene glycol having an average molecular weight of 2000 was added and the reaction was continued to obtain a solution of the polymer (b-8) with a concentration of 50 parts. The proportion of polyoxyethylene groups in the solid content of this solution was 84.

Polymer (b-9): 200 parts of polytetramethylene glycol with an average molecular weight of 1000 and 75 parts of MDI were charged into a polymerization vessel, and the reaction was carried out in the same manner as in (B-1) to obtain MEK 6.
75 parts, 400 parts of polyoxyethylene glycol having an average molecular weight of 2000, and 0.02 parts of dibutyltin dilaurate were added to continue the reaction to obtain a solution of polymer (b-9) with a concentration of 50%. The proportion of polyoxyethylene groups in the solid content of this solution was 59%.

Examples 1 to 6 and Comparative Examples 1 to 4 Hydrophobic polyurethane polymer dispersion 1 A hydrophilic polyurethane polymer solution, an organic solvent, and water were stirred with a homomixer to prepare a polyurethane emulsion.

This emulsion was applied to a glass plate and then dried. The formulation and sheet manufacturing conditions are shown below. Hydrophobic polymer dispersion 90 parts Hydrophilic polymer solution 6 parts (hydrophobic polymer/hydrophilic polymer solids ratio 90/10) Organic solvent MEK 24 parts Toluene 20 parts Water 70 parts Emulsion Solid concentration 15.47 parts Coating amount 200 parts Drying conditions 60°C x 3 minutes 120°QX8 distribution (However, in Comparative Example 4, no hydrophilic polymer solution was used. (96 parts of a hydrophobic polymer dispersion liquid was used.) Table 1 shows the hydrophobic polymer and hydrophilic polymer used, the viscosity of the obtained emulsion, and the physical properties of the sheet.

Example 7 A polyurethane emulsion was prepared in the same manner as in Example 1, impregnated into a nonwoven fabric, and then dried. The compounding recipe and sheet manufacturing conditions are shown below.

Hydrophobic polymer dispersion 90 parts Hydrophilic polymer solution 6 parts (hydrophobic polymer/hydrophilic polymer solids ratio 90/10) Organic solvent Ethyl acetate 54 parts!・Luene 20 parts Water 50 parts Emulsion solid content concentration 15.0 parts Impregnated amount 500 Boiling and drying conditions 70"OX 5 minutes 120°C x 5 minutes Hydrophobic polymer and hydrophilic polymer used and 1. Obtained milk Table 1 shows the viscosity of the suspension and the physical properties of the sheet.

Table 1 Viscosity and sorting properties of polyurethane emulsion Note)
* According to JISK6828.

Table 1 shows that the polyurethane emulsion of the present invention has good stability;
In addition, a sheet material with uniform to slightly porous properties and excellent moisture permeability can be obtained by drying in an extremely short period of time.

Claims (1)

[Scope of Claims] 1. A method for producing a porous sheet material in which a polyurethane emulsion consisting of a hydrophobic polyurethane polymer, a hydrophilic polyurethane polymer, an organic solvent, and water is applied or impregnated onto a substrate and dried. A hydrophobic polyurethane polymer (A) consisting of a polymeric diol component, an organic diisocyanate component and a chain extender component (B) a hydrophilic polyurethane polymer (B) represented by the following general formula (1), G-+R-E+FrR -G, (1) However, R: a portion of a hydrophobic isocyanate-terminated prepolymer. E=chain extender moiety. G: polyoxyethylene glycol moiety. A positive number between nil and 8. A method for producing a porous sheet material characterized by using an organic solvent (Cl) that has limited mutual solubility with water, and a polyurethane emulsion consisting of water. The molecular diol component and organic diisocyanate component have an NC010H ratio of 1.6 to 2.
. 3. The hydrophilic polyurethane polymer (B) is 42~. 3. A method according to claim 2, containing 60 weight polyoxyethylene chains. 4. The organic solvent (q has a water solubility of 1 to 50 g at 20°C)
(based on 100g of organic solvent) and has a boiling point of 5oQ12oC at normal pressure.