JPH0637751B2 - Porous sheet material and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a porous sheet material and a method for producing the same,
It is an object of the present invention to provide a porous sheet material excellent in various properties such as mechanical properties, water vapor permeability, water resistance and solvent resistance with high productivity.

(Prior Art) Conventionally, a large number of porous sheet materials made of polyurethane as natural leather substitutes, fiber coating products and the like and methods for producing them have been known, and can be roughly classified into a wet method and a dry method.

(Problems to be Solved by the Invention) Both methods have advantages and disadvantages, and the dry method is superior in terms of productivity.

Examples of such a dry method include JP-B-48-4380, JP-B-48-8742, and JP-A-51-410.
The methods described in JP-A-63, JP-A-54-66961, JP-A-54-68498 and the like are known.

According to these known methods, a porous sheet material having excellent performance is provided, but in order to obtain a product having excellent performance by these methods, the organic solvent used in the polyurethane emulsion used is used. Since it is necessary to selectively evaporate water and water, very strict temperature control is required for gelation and drying, and a relatively long time, for example, 30 minutes to 1 hour is required. Despite the possibility of being continuous, there is the problem of very low productivity due to this gelling and drying process.

Further, as the dispersant or emulsifier of the emulsion to be used, a hydrophilic portion having a polyoxyethylene segment other than polyoxyethylene or a polyester segment as the hydrophobic portion and a polyoxyethylene segment as the hydrophilic portion. Although polyurethane is used, such a hydrophobic portion has an ether bond or an ester bond that is hydrophobic but hydrophilic and has an affinity for a solvent, so that the dispersing effect or the emulsifying effect is not sufficient, and the emulsion is Storage stability and emulsion stability at the time of heating on the substrate sheet are insufficient, and there is a problem in the process from this point as well.

Further, the emulsifier has a role of emulsifying and stabilizing the hydrophobic polyurethane into a W / O type in the method for producing the porous sheet material, and further causes water to promptly act on the hydrophobic polyurethane to form the hydrophobic polyurethane in the film formation. Although having a role of uniformly gelling, the emulsifier has a negative effect on water resistance, solvent resistance, adhesion resistance, coating strength, etc. for the porous layer formed from being hydrophilic, In addition, there were significant quality problems such as washing resistance, dry cleaning resistance, and deterioration of coating strength.

Therefore, in order to improve productivity and quality, the problems of stability during storage of the emulsion used in the above-described method and stability during heating on the substrate are solved, and gelation and The gelling and drying process can be completed within 10 minutes or less, preferably within a few minutes, without requiring strict control of the drying process, and the washing resistance and dry cleaning resistance are excellent, and the flexibility and film strength are excellent. There is a strong demand in the industry for the development of technology that can provide quality products.

The present inventor has responded to the above-mentioned demands of the prior art, solves the problem of low emulsion stability as in the conventional method, and complicates the selective evaporation of the organic solvent and water in the gelation and drying steps. A method capable of providing an excellent quality product having excellent softness and film strength, which is excellent in washing resistance and dry cleaning resistance, in which gelling and drying steps are completed in 10 minutes or less. As a result of intensive research to obtain the above, when using a specific hydrophilic polyurethane as one component of the polyurethane emulsion used in these methods, the drawbacks of the prior art as described above are solved, and The present invention has been completed with the knowledge that it is possible to sufficiently meet the above demands.

(Means for Solving Problems) That is, according to the present invention, in a porous sheet material in which a porous layer composed of hydrophobic polyurethane and hydrophilic polyurethane is provided on a substrate, the hydrophilic polyurethane is used as a hydrophobic portion. A porous sheet material comprising a polybutadiene segment and a polyoxyethylene segment as a hydrophilic segment, and a method for producing the same.

(Operation) By using, as a dispersant or emulsifier for the hydrophobic polyurethane constituting the emulsion, a block polyurethane of a polybutadiene segment having a high degree of hydrophobicity and a high solvent resistance and a polyoxyethylene segment having a high degree of hydrophilicity, The stability of the emulsion is remarkably improved by using a small amount, and it is possible to dry and gel at a relatively high temperature for a short time, good washing resistance and dry cleaning resistance, flexible and excellent in film strength. A porous sheet material having a porous structure is provided.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to a preferred embodiment.

The hydrophobic polyurethane itself used in the method of the present invention may be a known material, and can be obtained, for example, by reacting a hydrophobic polyol, an organic diisocyanate and a chain extender.

Examples of the hydrophobic polyol include polyethylene adipate having a hydroxyl group as a terminal group and a molecular weight of 300 to 4,000, polyethylene propylene adipate, polyethylene butylene adipate, polydiethylene adipate, polybutylene adipate, polyethylene succinate, polybutylene succinate. Polyethylene sebacate, polybutylene sebacate, polytetramethylene ether glycol, poly-ε-caprolactone diol, polyhexamethylene adipate, carbonate polyol, polypropylene glycol and other C ₃ or higher poly (oxyalkylene) glycols, polybutadiene glycols and the like Examples include hydrogenated products.

As the organic diisocyanate, 4,4'-diphenylmethane diisocyanate (MD
I), hydrogenated MDI, isophorone diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 2,4-tolylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene There are diisocyanates and the like, or urethane polymers obtained by reacting these organic diisocyanates with low molecular weight polyols and polyamines so as to become terminal isocyanates can naturally be used.

As the chain extension, ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, ethylenediamine, 1,2-propylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, decamethylene Examples include diamine, isophoronediamine, m-xylylenediamine, and hydrazine water.

Both hydrophobic polyurethanes obtained from the materials as described above and commercially available hydrophobic polyurethanes can be used in the present invention, but the most preferable one is to synthesize these hydrophobic polyurethanes in a specific organic solvent and disperse them. It is obtained as a liquid or a solution.

For example, a dispersion or solution of hydrophobic polyurethane is prepared by reacting at least the above-mentioned three components in an organic solvent having a mutual solubility of hydrophobic polyurethane with water and preferably having a boiling point of 120 ° C. or less at normal pressure. Can be obtained. The reaction conditions such as temperature and time may be conventionally known conditions.

Preferred as the organic solvent is methyl ethyl ketone,
Methyl-n-propyl ketone, methyl isobutyl ketone, diethyl ketone, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, butyl acetate, etc., and also acetone, cyclohexane, tetrahydrofuran, dioxane, methanol, ethanol, isopropyl. Alcohol, butanol, toluene, xylene, dimethylformamide, dimethylsulfoxide, perchlorethylene, trichloroethylene, methylcellosolve, butylcellosolve, cellosolve acetate and the like can also be used.

Those which have no limit in mutual solubility with water in these organic solvents or those which do not dissolve in water at all are used as a mixture with other organic solvents with a limit in mutual solubility with water.
Of course, the above organic solvents can be used as a mixed organic solvent.

By preparing the hydrophobic polyurethane in such an organic solvent, a dispersion or solution thereof can be obtained, and its solid content is adjusted to the range of about 5 to 60% by weight by adding or removing the same solvent or another solvent. Is convenient.

The hydrophilic polyurethane, which is used as a dispersant or an emulsifier in the present invention and mainly characterizes the present invention, is characterized by containing a polybutadiene segment as a hydrophobic portion and having a polyoxyethylene segment as a hydrophobic segment. And / or polybutadiene polyol as part of the polyol component
Alternatively, it can be obtained by using a water-added polybutadiene polyol and using polyoxyethylene glycol as another part of the polyol component according to a known method for producing a polyurethane resin.

According to a detailed study by the present inventor, in a method for producing a porous sheet material, a conventional emulsifier emulsifies and stabilizes a hydrophobic polyurethane into a W / O type, and further water is rapidly converted into the hydrophobic polyurethane in forming a film. Although it has a role of gelling it uniformly by contacting it, the emulsifier has high hydrophilicity as a whole because it also contains an ether bond or an ester bond even in its hydrophobic portion, and the water resistance of the formed film,
It adversely affects solvent resistance, adhesion resistance, and film strength, and the present invention aims to eliminate such adverse effects.

That is, a conventional hydrophilic polyurethane used as a dispersant or an emulsifier of a conventional polyurethane emulsion, that is, having a polyoxypropylene or polyester segment as a hydrophobic portion, and a polyoxyethylene segment as a hydrophilic portion. In the polyurethane-based dispersant or emulsifier having, by replacing all or most of these hydrophobic moieties with polybutadiene segments, the hydrophobic moieties are, for example, hydrophobic polyols such as polyoxytetramethylene, polyoxypropylene and polyester. Unlike segments, it does not contain polar groups that have affinity for solvents with hydrophilic water such as ether and ester bonds, and rarely shows strong hydrophobicity, so a small amount can be used and stable and high dispersion or emulsification performance can be obtained. And also has a strong coagulation force for water Therefore, by using such a specific hydrophilic polyurethane as a dispersant or an emulsifier of a hydrophobic polyurethane, it is possible to achieve a simple and short-time gelation and drying step which could not be achieved by a conventionally known method. It was discovered that it is possible to provide a porous polyurethane sheet material having excellent productivity, flexibility, film strength, washing resistance, dry cleaning resistance and the like.

The polybutadiene polyol and the water-added polybutadiene polyol used for producing the hydrophilic polyurethane containing the polybutadiene segment as described above are conventionally known and can be easily obtained and used from the market. These polybutadiene glycol and its water additive are, for example,
It can be represented by the following structural formula, and its molecular weight is not particularly limited, but particularly preferred is an average molecular weight of 1,000.
To about 5,000.

Further, polyethylene glycol itself used for constituting the hydrophilic portion is well known, and any known polyoxyethylene glycol can be used in the present invention.
A particularly preferred one has an average molecular weight of 500 to 20,0.
It is about 00.

As the organic diisocyanate to be used, any of the conventionally known organic diisocyanates or terminal isocyanate prepolymers described above can be used. In the production of hydrophilic polyurethane, a part of the low molecular weight chain extender as described above can be used, and any known method can be used for producing hydrophilic polyurethane from such a material.

The amount of polybutadiene segment in the hydrophilic polyurethane thus obtained is preferably in the range of about 90 to 45% by weight in the whole hydrophilic polyurethane, while the amount of polyoxyethylene segment is about 10 to 4%.
A range of 5% by weight is preferable. In addition, within the range not hindering the object of the present invention, a conventionally known hydrophobic polyether segment or polyester segment is, for example,
It is also possible to include in the range of occupying 20 to 20% by weight.

The polyurethane emulsion used in the present invention comprises the above-mentioned hydrophobic polyurethane, preferably the above-mentioned dispersion or solution in an organic solvent and the above-mentioned hydrophilic polyurethane (or a solution thereof) in a solid content by weight ratio. Polyurethane / hydrophilic polyurethane = 80 to 99/20 to 1 by mixing, and the total solid content is adjusted to about 5 to 60% by weight,
This mixture dispersion or solution is stirred vigorously while being added with water at a saturated amount or less, for example, 50 to 500 parts by weight of water per 100 parts by weight of solid content in the mixture dispersion or solution. To be

The polyurethane emulsion thus obtained is a milky white cream-like fluid, which maintains a stable state even when left as it is for several months, and is stable even during gelation and drying. It keeps a good state.

Various additives, for example, known additives such as colorants, crosslinking agents, stabilizers, and fillers can be optionally added to such a polyurethane emulsion.

Examples of the base material used in the present invention include various woven fabrics,
Any substrate such as knitted cloth, non-woven cloth, release paper, plastic film, metal plate, glass plate may be used.

The method of applying the polyurethane emulsion to the substrate is
For example, any known method such as a coating method, a dipping method, or a combination method thereof may be used, and the impregnation and / or coating amount thereof is about 5 to 2,000 g (blended liquid) / m ² .
It can be changed in a wide range according to the purpose.

The gelling and drying step in the method of the present invention can be completed in a very short time and without requiring complicated processing. In the dry method as in the method of the present invention, the gelling and drying method is a porous sheet material. From the point of being the rate-determining step of the productivity, the gelation and drying in such a short time are extremely advantageous effects as compared with the conventional method.

That is, the impregnated and / or coated base material is disclosed in
The desired porous sheet material of the present invention can be obtained without any coagulation step as described in JP-41063-A, and only by gelling and drying at about 60 to 150 ° C. for about 1 to 10 minutes.

The gelling and drying treatment in such a short time is realized because the hydrophobic polyurethane used as the film forming agent in the present invention accounts for the majority of the total polyurethane, is an emulsifier, and is very hydrophobic. It is considered that it is because a small amount of hydrophilic polyurethane containing a highly polybutadiene segment stably disperses and emulsifies it with water, and when dried, it makes contact with water quickly and easily due to evaporation of the organic solvent, and gelation occurs. .

(Effect) The porous sheet material obtained by the present invention as described above has an extremely fine pore structure, is flexible, and is excellent in various physical properties such as film strength, water resistance, and solvent resistance, and is excellent. Having water vapor permeability, various synthetic leather materials, clothing, shoes,
It is useful as a filter for waterproof cloth, tent, wallpaper, floor material, filter material, air conditioner, etc.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples. In the text, all parts or% are based on weight unless otherwise specified.

Examples 1 to 6 (Production of Hydrophobic Polyurethane and Hydrophilic Polyurethane) Example 1 Polytetramethylene glycol (average molecular weight about 100)
0, hydroxyl value 112) 1,000 parts, ethylene glycol 93 parts and diphenylmethane diisocyanate 625
Part was added to 1,500 parts of methyl ethyl ketone, and the temperature was 60 ° C.
After reacting for 8 hours, add 2,500 parts of methyl ethyl ketone and cool to room temperature with stirring to obtain a solid content of 30%.
A milky white polyurethane dispersion (1) was obtained.

Example 2 1,4-Butadiethylene adipate (average molecular weight about 1,
000, hydroxyl value 112) 1,000 parts, 1,4-butanediol 144 parts, methyl ethyl ketone 1,144 parts and diphenylmethane diisocyanate 650 parts 70 parts
After reacting at ℃ for 8 hours, add 3,042 parts of methyl ethyl ketone to homogenize, cool to room temperature with stirring,
A milky white polyurethane dispersion (2) having a solid content of 30% was obtained.

Example 3 1,4-butane ethylene adipate (average molecular weight about 1,
000, hydroxyl value 112) 1,000 parts and 408 parts isophorone diisocyanate are reacted at 100 ° C. for 6 hours,
1,230 parts of methyl ethyl ketone, 1,230 of toluene
Parts, n-butanol at 1 ° C. for 6 hours, then, 1,230 parts of methyl ethyl ketone, 1,230 parts of toluene, 1,230 parts of n-butanol and 148 parts of isophoronediamine were added, and the mixture was stirred to homogenize sufficiently to obtain a solid content. A 30% polyurethane solution (3) was obtained.

Example 4 α, ω-polybutadiene glycol (average molecular weight about 1,
000, hydroxyl value 112) 1,000 parts and 252 parts tolylene diisocyanate are reacted at 80 ° C. for 3 hours, then 500 parts of methyl ethyl ketone are added to homogenize the reaction system, and polyoxyethylene glycol is added therein. (Average molecular weight of about 1,000 and hydroxyl value of 112) 900 parts was added and reacted at 75 ° C. for 6 hours, 1,652 parts of methyl ethyl ketone was further added, and the mixture was stirred uniformly to obtain a solid content of 5
A polyurethane solution (4) having 0%, a polybutadiene segment content of 46.5% and a polyoxyethylene segment content of 41.8% was obtained.

Example 5 1,000 parts of water-added α, ω-polybutadiene glycol (average molecular weight of about 3,000, hydroxyl value of 28) was reacted with 57 parts of isiphorone diisocyanate at 100 ° C. for 3 hours, and then 500 parts of methyl ethyl ketone was added. Then, the reaction system is sufficiently homogenized, and polyoxyethylene glycol (average molecular weight about 1,000, hydroxyl value 112) is added therein.
0 part was added and reacted at 75 ° C. for 6 hours, 722 parts of methyl ethyl ketone was further added, and the mixture was stirred uniformly to give a solid content of 5
0%, water-containing polybutadiene segment content 81.9
%, And a polyoxyethylene segment content of 12.3% was obtained to obtain a polyurethane solution (5).

Example 6 α, ω-polybutadiene glycol (average molecular weight about 2,
000, hydroxyl value 52.0) 1,000 parts and 4,4'-
80 ° C with 139 parts of diphenylmethane diisocyanate
After reacting for 3 hours at room temperature, 500 parts of methyl ethyl ketone was added to homogenize the reaction system, and 371 parts of polyoxyethylene glycol (average molecular weight about 2,000, hydroxyl value 56.0) was added thereto at 75 ° C. At room temperature for 5 hours, and add 1,010 parts of methyl ethyl ketone.
By uniformly stirring, a polyurethane solution (6) having a solid content of 50%, a polybutadiene segment content of 66.2% and a polyoxyethylene segment content of 24.6% was obtained.

Comparative Examples A to C Comparative Example A Polyoxytetramethylene glycol (average molecular weight about 2,000, hydroxyl value 56) 1,000 parts and 4,4'-
80 parts of diphenylmethane diisocyanate and 150 parts
After 3 hours of reaction, 500 parts of methyl ethyl ketone was added to homogenize the reaction system, and 400 parts of polyoxyethylene glycol (average molecular weight about 2,000, hydroxyl value 56) was added thereto at 75 ° C. The mixture was reacted for 5 hours, 1050 parts of methyl ethyl ketone was further added, and the mixture was stirred uniformly to obtain a polyurethane solution having a solid content of 50%, a polyoxytetramethylene segment content of 64.5%, and a polyoxyethylene segment content of 25.8% ( A) got

Comparative Example B Polyoxypropylene glycol (average molecular weight about 2,0
00, hydroxyl value 56) 1,000 parts and 4,4′-diphenylmethane diisocyanate 188 parts were reacted at 80 ° C. for 3 hours, and then 500 parts of methyl ethyl ketone was added to homogenize the reaction system. Polyoxyethylene glycol (average molecular weight about 1,000, hydroxyl value 11
2) Add 500 parts and react at 75 ° C for 5 hours, and
188 parts of methyl ethyl ketone was added and stirred uniformly to obtain a polyurethane solution (B) having a solid content of 50%, a polyoxypropylene segment content of 59.3% and a polyoxyethylene segment content of 29.6%.

Comparative Example C 1,4-butane ethylene adipate (average molecular weight about 2,
000, hydroxyl value 56) 1,000 parts and water addition 4,4 '
80 parts of 170 parts of diphenylmethane diisocyanate
After reacting at ℃ for 3 hours, add 500 parts of methyl ethyl ketone to homogenize the reaction system sufficiently, add 300 parts of polyoxyethylene glycol (average molecular weight about 1,000, hydroxyl value 112) to 75 ℃. For 5 hours, 970 parts of methyl ethyl ketone is further added, and the mixture is stirred uniformly to obtain a solid content of 50%, 1,4-butaneethylene adipate segment content of 68.0%, and polyoxyethylene segment content of 20.4%. Polyurethane solution (C)
Got

Examples 7 to 10 and Comparative Examples D to F (Production of Polyurethane Emulsion) The products of Examples 1 to 6 and Comparative Examples A to C, the organic solvent and water were stirred with a homomixer, and the following polyurethane W /
An O 2 emulsion was prepared. The stability of these emulsions is shown in Table 1 below.

Example 7 Polyurethane emulsion (7) Polyurethane dispersion (1) 100 parts Polyurethane solution (4) 2 parts Methyl ethyl ketone 20 parts Toluene 20 parts Water 60 parts Example 8 Polyurethane emulsion (8) Polyurethane dispersion (1) 100 parts Polyurethane solution (4) 12 parts Methyl ethyl ketone 20 parts Toluene 20 parts Water 60 parts Example 9 Polyurethane emulsion (9) Polyurethane dispersion (2) 100 parts Polyurethane solution (5) 4 parts Methyl ethyl ketone 150 parts Xylol 20 parts Water 70 parts Example 10 Polyurethane emulsion (10) Polyurethane solution (3) 100 parts Polyurethane solution (6) 2.5 parts Toluene 30 parts Methyl ethyl ketone 20 parts Water 90 parts Commercial emulsion water repellent 2 parts Comparative Example D Polyurethane milk Suspension (D) Polyurethane solution (3 100 parts Polyurethane solution (A) 2.5 parts Toluene 30 parts Methyl ethyl ketone 20 parts Water 90 parts Commercial emulsion-based water repellent 2 parts Comparative Example E Polyurethane emulsion (E) Polyurethane solution (3) 100 parts Polyurethane solution (B) 2.5 parts Toluene 30 parts Methyl ethyl ketone 20 parts Water 90 parts Commercial emulsion water repellent 2 parts Comparative Example F Polyurethane emulsion (F) Polyurethane solution (3) 100 parts Polyurethane solution (C) 2.5 parts Toluene 30 parts Methyl ethyl ketone 20 parts Water 90 parts Commercial emulsion-based water repellent 2 parts The stability of the emulsion is shown when it is left in a constant temperature atmosphere of 35 ° C.

Examples 11 to 14 and Comparative Examples G to J Various substrates were impregnated and / or coated with the polyurethane emulsion of Table 1 to obtain various porous sheet materials of the present invention and comparative examples, respectively. . The production conditions and results are shown in Tables 2 and 3 below.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masashi Kashimura 4-18-13 Ukima, Kita-ku, Tokyo (72) Inventor Tomoko Goto 4-4-33 Nishi-Aoki, Kawaguchi City, Saitama Prefecture

Claims (2)

[Claims] 1. A porous sheet material comprising a substrate and a porous layer comprising a hydrophobic polyurethane and a hydrophilic polyurethane, wherein the hydrophilic polyurethane has a polybutadiene segment as a hydrophobic portion and a polybutadiene segment as a hydrophilic segment. A porous sheet material, which is a hydrophilic polyurethane having an oxyethylene segment. 2. A porous sheet formed by impregnating and / or coating a substrate with a water-in-oil type polyurethane emulsion comprising hydrophobic polyurethane, hydrophilic polyurethane, an organic solvent and water, gelling and drying. In the method of manufacturing the material,
A method for producing a porous sheet material, wherein the hydrophilic polyurethane is a hydrophilic polyurethane having a polybutadiene segment as a hydrophobic portion and a polyoxyethylene segment as a hydrophilic segment.