JP2011225807A - Method of producing polyurethane porous body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing polyurethane porous body showing smaller shrinkage ratio during a drying step, wherein a planned product can be stably manufactured.SOLUTION: The method includes: a step of mixing a mixture containing a polyurethane resin, a solvent and calcium chloride anhydrous with a liquid mixture to obtain a mixed composition, wherein in the liquid mixture, the weight ratio of water to the solvent equals the ratio of 10 to 90, to that of 75 to 25; a step of molding the mixed composition; a step of solidifying the resultant compact; and a step of performing aqueous extraction of the calcium chloride anhydrous from the solidified compact to remove the calcium chloride anhydrous and drying the resultant compact.

Description

  The present invention relates to a method for producing a polyurethane porous body by a wet coagulation method, and more particularly to a method for producing a polyurethane porous body obtained by removing anhydrous calcium chloride from a molded body that has undergone a coagulation step.

  Polyurethane porous bodies using polyurethane resins are used as cushion materials, cosmetic sponges, and the like. A wet coagulation method is well known as one method for producing such a polyurethane porous body. For example, a kneaded composition in which a polyurethane resin, a solvent and an inorganic salt are kneaded is prepared, and the kneaded composition is defoamed and molded. Disclosed are a step, a step of solidifying the obtained molded body in water, and a method of extracting and removing inorganic salts from the solidified molded body, followed by drying (Patent Documents 1 and 2).

  However, according to the study by the present inventors, for example, among the inorganic salts, in the wet coagulation method using calcium chloride, for example, when calcium chloride having an average particle size of about 20 μm and a relatively small particle size is used. It has been found that the shrinkage ratio of the molded body increases before and after the drying step, and the molded body as designed may not be manufactured.

JP 2001-233987 A JP 2006-152202 A

  The present invention has been made in view of the above circumstances, and its main object is to provide a method for producing a polyurethane porous body that has a small shrinkage rate in the drying step and can stably produce a product as designed. There is to do.

  As a result of intensive investigations to solve the above problems, the present inventors have added and kneaded a mixture of water and a solvent having a predetermined weight ratio to a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride. The inventors have found that the above problems can be solved, and have completed the present invention.

That is, the gist of the present invention is as follows.
[1] A step of kneading a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride, and a mixed solution in which the weight ratio of water to the solvent is water / solvent = 10/90 to 75/25 to obtain a kneaded composition, Manufacture of a polyurethane porous body having a step of molding the kneaded composition, a step of coagulating the obtained molded body, and a step of water-extracting and removing anhydrous calcium chloride from the solidified molded body, followed by drying Method.
[2] The method for producing a polyurethane porous body according to the above [1], wherein the anhydrous calcium chloride has an average particle size of 100 μm or less.
[3] The method for producing a polyurethane porous body according to the above [2], wherein the content of the polyurethane resin in the kneaded composition is 20% by weight or less.
[4] Cosmetic sponge, cushion material, OA equipment roller, water absorption roller, liquid draining roller, conductive roller, ink roller, water absorption sheet, swab, medical sponge, chemical liquid application head rubber, penetrating mark, brush pen or filter The method for producing a polyurethane porous body according to the above [3], which is used in a method.
[5] A polyurethane porous body produced by the method according to [3].
[6] Cosmetic sponge, cushion material, OA equipment roller, water absorption roller, liquid draining roller, conductive roller, ink roller, water absorption sheet, swab, medical sponge, head rubber for chemical application, penetrating mark, brush pen or filter The polyurethane porous body according to the above [5], which is used in the above.

  According to the present invention, a kneaded composition is prepared by kneading a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride, and a liquid mixture in which the weight ratio of water to the solvent is water / solvent = 10/90 to 75/25. Thus, there is provided a method for producing a polyurethane porous body in which the shrinkage rate in the drying step is small and a product as designed is stably produced.

  As described above, the method for producing a porous polyurethane body according to the present invention comprises a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride, and the weight ratio of water to the solvent is from water / solvent = 10/90 to 75/25. And kneading the mixed liquid to obtain a kneaded composition, the step of molding the kneaded composition, the step of solidifying the obtained molded body, and removing the anhydrous calcium chloride from the solidified molded body by water extraction. , And then drying.

  First, in the present invention, a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride is prepared.

  The polyurethane resin used as a raw material is obtained by reacting a polyol, a chain extender and a polyisocyanate.

  The polyol is not particularly limited as long as it is used in the production of ordinary polyurethane resins and has two or more hydroxyl groups in the molecule. For example, polyether polyol, polyester polyol, polycarbonate polyol, polylactone polyol, polyolefin polyol , Acrylic polyols, castor oil-based polyols, silicone-based polyols, and the like. These can be used alone or in admixture of two or more. Among these, polycarbonate polyol is preferably used from the viewpoint of suppressing deterioration of the resulting polyurethane porous body. The deterioration mentioned above includes deterioration due to light, deterioration due to heat, deterioration due to water, and the like.

  As the polyether polyol, those obtained by polymerizing or copolymerizing alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) and / or heterocyclic ether (tetrahydrofuran, etc.), specifically, polyethylene glycol, polypropylene glycol, Examples include polyethylene-polypropylene (block or random) glycol, polyethylene-tetramethylene (block or random) glycol, polytetramethylene glycol, poly-2-methyltetramethylene glycol, polyhexamethylene glycol, and the like. Alternatively, an amine ether polyol obtained by adding an alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) to an amine compound (mono or diamine, hydrazine, substituted hydrazine, etc.) can be used.

  Polyester polyols include aliphatic dicarboxylic acids (succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, etc.) and / or aromatic dicarboxylic acids (orthophthalic acid, isophthalic acid, terephthalic acid, 1,5-naphthalenedicarboxylic acid) Etc.) and low molecular glycols (ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol) , Pentaerythritol, 1,4-dihydroxymethylcyclohexane, etc.), specifically polyethylene glycol adipate, polybutanediol adipate, polyhexanediol adipate, poly-3-methylpentanedio Ruajipeto, poly neopentyl glycol adipate, polyethylene / butylene adipate diol, polyneopentyl / hexyl adipate diol, polybutylene isophthalate diol.

  Polycarbonate polyols include polybutanediol carbonate, poly-3-methylpentanediol carbonate, polyhexanediol carbonate, polynonanediol carbonate, polybutanediol hexanediol carbonate, polypentanediol hexanediol carbonate, and poly-2-methyloctanediol. Nonanediol carbonate, poly-3-methylpentanediol hexanediol carbonate, and the like.

  Examples of the polylactone polyol include polycaprolactone diol, polycaprolactone triol, and poly-3-methylvalerolactone diol.

  Examples of the polyolefin polyol include polybutadiene glycol, polyisoprene glycol or a hydride thereof.

  Silicone polyols are those in which hydroxyl groups are introduced into the polysiloxane main chain. Further, the introduced hydroxyl groups may be at both ends or one end of the polysiloxane main chain.

  The chain extender is not particularly limited as long as it is a short-chain diol compound that is used in the production of ordinary polyurethane resins and has two or more hydroxyl groups in the molecule. For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methylpentanediol, nonanediol, octanediol, dimethylolheptane, 1 , 4-cyclohexanediol and the like, and these can be used alone or in admixture of two or more.

  In the present invention, in addition to the short-chain diol compound described above, for example, a polyamine can be used as a chain extender. The polyamine is not particularly limited as long as it is a compound used in the production of a normal polyurethane resin and has two or more amino groups in the molecule. For example, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, triethylenetetramine Aliphatic amines such as 1,3-bis (aminomethyl) cyclohexane, 1,4-cyclohexanediamine, 3-aminomethyl-3,5-trimethylcyclohexylamine, isophoronediamine, piperazine, 2-methylpiperazine, 2,5 -Dimethylpiperazine, cis-2,6-dimethylpiperazine, N, N'-bis (3-aminopropyl) piperazine, 4,4'-cyclohexylmethanediamine, triethylenetetramine, 1- (2-aminoethyl) piperazine, etc. Of alicyclic amines; 4,4'- Aminodiphenylmethane, 3,3′-dimethyl 4,4′-diaminodiphenylmethane, xylenediamine, phenylenediamine, 1,5-naphthenediamine, toluene-2,4-diamine, toluene-2,6-diamine, 3,3 ′ -Aromatic amines, such as dimethylbenzidine, etc. are mentioned, These can be used individually or in mixture of 2 or more types.

  The polyisocyanate is not particularly limited as long as it is used for the production of a normal polyurethane resin and has two or more isocyanate groups at the terminal. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4 , 4'-diphenylmethane diisocyanate, 3,3'-dichloro-4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, crude diphenylmethane isocyanate, xylylene diisocyanate, phenylene diisocyanate, 1 , 5-Naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate and other aromatic polyisocyanates and hydrogenated products thereof; 1,4- Alicyclic polyisocyanates such as chlorohexane diisocyanate, isophorone diisocyanate, norbornane diisocyanate; and aliphatic polyisocyanates such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dimer acid diisocyanate, lysine diisocyanate, etc. Or 2 or more types can be mixed and used.

  Examples of the solvent used as a raw material include organic solvents such as acetone, dimethylformamide (DMF), dimethyl sulfoxide, N-methylpyrrolidone, methyl ethyl ketone, dioxane, tetrahydrofuran, and mixtures thereof. DMF is preferably used because it can be extracted.

  In the present invention, anhydrous calcium chloride is used as the raw material inorganic salt in order to reduce the shrinkage rate in the drying step described later. In this specification, “the shrinkage rate in the drying step is small” means that the shrinkage rate in the vertical and horizontal directions of the polyurethane porous body is less than 10% before and after the drying step. The average particle size of anhydrous calcium chloride is usually 100 μm or less because the kneading time can be shortened. In the present specification, the “average particle diameter” refers to a volume average diameter calculated from a particle size distribution measured on a volume basis using a laser diffraction particle size distribution measuring apparatus. Moreover, 5-50 micrometers is preferable as an average particle diameter at the point which makes the cell of a porous body fine, 5-30 micrometers is more preferable, and 5-20 micrometers is further more preferable.

  According to the study by the present inventors, when a polyurethane porous body is produced by a wet coagulation method using a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride, the shrinkage ratio in the drying step and the average of anhydrous calcium chloride are determined. It was found that there is a large correlation with the particle size, and that the shrinkage rate in the drying process increases as the smaller average particle size is used. Specifically, when anhydrous calcium chloride having an average particle size of more than 100 μm is used, the shrinkage rate in the drying process is relatively small (the shrinkage rate is 15% or less at the maximum) without using a mixed liquid described later. Can hold. On the other hand, when anhydrous calcium chloride having an average particle size of 100 μm or less is used, it is difficult to reduce the shrinkage rate in the drying process unless a mixed solution described later is used. Therefore, as described above, when anhydrous calcium chloride having an average particle diameter of 100 μm or less is used as described above, it is essential to use a mixed liquid described later from the viewpoint of reducing the shrinkage rate in the drying step.

  When preparing a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride, the above three kinds of raw materials may be stirred and kneaded at the same time. For example, a polyurethane resin solution produced with a solid content of 25 to 40% by weight It is also possible to add and knead a solvent and anhydrous calcium chloride. As the solvent used in this case, the same solvent as that used in the polyurethane resin solution is preferable in terms of solubility. For example, when using a polyurethane resin having a solid content of 30% by weight, the solvent is 0 to 100 parts by weight (preferably 20 to 70 parts by weight) and the anhydrous calcium chloride is 20 to 70 parts by weight with respect to 100 parts by weight of the polyurethane resin. It can mix | blend in the range (preferably 25-65 weight part). In addition to the raw materials, the mixture may further contain known additives such as surfactants, colorants, weathering agents, and antibacterial agents as necessary.

  For preparation of the mixture, for example, kneader, planetary mixer, propeller mixer, ribbon mixer, single or twin screw extruder, Banbury mixer, etc. Machine is preferred. Each said raw material is knead | mixed normally for 5 to 60 minutes in the temperature range of 10-50 degreeC.

  Subsequently, the mixture obtained above and a mixed liquid composed of water and a solvent are kneaded to prepare a kneaded composition. The solvent used in the mixed solution is preferably the same as the solvent used in the preparation of the mixture from the viewpoint of solubility. The weight ratio of water and solvent in the mixed solution is preferably in the range of water / solvent = 10/90 to 75/25 in order to reduce the shrinkage rate in the drying step described later, and is 15/85 to 70/30. A range is more preferred. In addition, kneading compositions can be easily stirred and kneaded even with high viscosity, such as kneaders, planetary mixers, propeller mixers, ribbon mixers, single- or twin-screw extruders, Banbury mixers, etc. Can be mentioned. Usually, the mixed solution is added and kneaded in a state in which a mixer containing the prepared mixture is operated. The mixture and the mixed solution are kneaded usually at a temperature range of 10 to 50 ° C. for 5 to 30 minutes.

The polyurethane porous body produced according to the present invention may be required to have a relatively low density (apparent density of 0.15 to 0.30 g / cm ³ ) in relation to applications. In this case, the blending ratio of the polyurethane resin is usually in the range of 10 to 20% by weight in terms of solid content in the kneaded composition. As described above, the lower the density of the polyurethane porous body, the larger the shrinkage rate during drying. In the present invention, however, the shrinkage rate in the drying process can be reduced because the above-described mixed liquid is used.

  A kneaded composition is prepared as described above, and after completion of kneading, the kneaded composition is molded. If necessary, the kneaded composition may be defoamed during or after kneading the kneaded composition. A specific method of defoaming is not particularly limited as long as it is a method capable of removing air bubbles in the kneaded composition. For example, a method of performing degassing using a vented extruder, a vacuum hood, etc. Examples thereof include a method of stirring and kneading in a vacuum reduced state using the adopted planetary mixer, a method of leaving under a reduced pressure condition, a method of forcibly removing bubbles using a centrifuge and the like.

  A specific method of molding is not particularly limited as long as it is a known method. For example, an extruder is used to extrude the kneaded composition from the molding die, and the kneaded composition is put into a mold having a predetermined shape. Examples include injection, filling and shaping.

  Subsequently, the solvent is extracted from the molded body to produce a solidified molded body. As a specific method, if it is a well-known method, it will not specifically limit, For example, the method etc. which immerse the molded object shape | molded in the water tank containing about 10-50 degreeC water etc. are mentioned. The solidification time can be appropriately changed depending on the thickness of the molded body.

  Thereafter, anhydrous calcium chloride is extracted from the solidified shaped body by water extraction. The specific method for water extraction is not particularly limited as long as it is a known method, and examples thereof include a method of leaving in water, hand scrub washing, bubbling, and ultrasonic cleaning. In addition, a method in which the solidified molded body is put into a washing machine or the like, and stirred and washed with water at 10 to 50 ° C. for about 10 minutes to several hours.

  After the water extraction, the molded body from which anhydrous calcium chloride has been removed is dried at 130 ° C. or lower using a known dryer such as a constant air temperature type, a reduced pressure type, a dehumidifying type, or a tumbler type. In this way, a polyurethane porous body is produced.

  The resulting polyurethane porous body has a shrinkage ratio in the vertical and horizontal directions before and after drying of less than 10%, and the shrinkage ratio is significantly smaller than in the conventional method that does not use a mixture of water and solvent. Improved.

  Further, from the measurement results of hardness, tensile strength and elongation rate, the polyurethane porous body according to the present invention is, for example, a cosmetic sponge such as a cosmetic puff or eye shadow chip, a cushion material, a roller for OA equipment, a water absorption roller, Suitable as various draining rollers, conductive rollers, ink rollers, liquid absorbing members such as water absorbing sheets, swabs, medical sponges, application sponges such as liquid rubber head rubber, penetrating marks, brush pens, filters, etc. Can be used.

  EXAMPLES Hereinafter, examples and comparative examples of the present invention will be described more specifically, but the present invention is not limited to these examples.

(Examples 1-4)
1. Manufacture of a polyurethane porous body Circulating hot water at 40 ° C. with a jacketed planetary mixer (Inoue Seisakusho Co., Ltd., capacity: 5 L, model: PLM-5), with the blending ratio (weight ratio) shown in Table 1 , Polyurethane resin solution (Toyo Polymer Co., Ltd., HILACK MP-1051 SPN, polycarbonate-based polyurethane resin having a solid content of 30% using DMF as a solvent), DMF and anhydrous calcium chloride (average particle size: 20 μm) at a rotational speed of 60 rpm A kneaded composition was prepared by kneading for 20 minutes to obtain a mixture, and subsequently adding a mixture of water and DMF having the blending ratio (weight ratio) shown in Table 1 and kneading for 15 minutes. Next, the rotational speed of the planetary mixer was lowered to 40 rpm, and vacuum defoaming was performed for 10 minutes.
After visually observing the properties of the kneaded composition after defoaming, the kneaded composition was poured and filled into a disk-shaped mold having a diameter of 130 mm and a height of 20 mm, and then poured into a water tank having a water temperature of 17 to 20 ° C. The composition was allowed to solidify. When solidification of the kneaded composition proceeds, the boundary between the solidified part and the unsolidified part can be clearly seen by visually observing the cross section by cutting in the vertical direction. With the thickness as the solidified thickness, the solidified thickness after 24 hours, 48 hours and 72 hours was measured. Then, after the solidification was completed, the disk-shaped molded product was taken out of the mold and hand-washed with water at 40 to 50 ° C. for about 10 minutes to extract and remove anhydrous calcium chloride to obtain a wet polyurethane porous body. Table 2 shows the blending ratio, properties and coagulation thickness of the kneaded composition.
The average particle diameter of anhydrous calcium chloride is a volume average diameter calculated from the particle size distribution measured on a volume basis using a laser diffraction particle size distribution measuring device (SALD-2200) manufactured by Shimadzu Corporation. . The average particle diameters of anhydrous calcium chloride used in Examples 14 to 17 described later and calcium chloride dihydrate and sodium chloride used in Comparative Examples 4 and 10 to 13 are also values measured in the same manner as described above. .

2. Measurement of shrinkage before and after drying The entire surface of the wet polyurethane porous body is removed with a cutter, and two marked lines with a length of 10 mm or more are marked in the longitudinal (thickness) direction with an oil-based magic, and the transverse (diameter) direction. One marked line having a length of 90 mm or more was marked, and after measuring the length of each marked line with a caliper, it was dried at 80 ° C. for 15 hours using a blast constant temperature dryer. After drying, the lengths of the vertical and horizontal marked lines are measured with a caliper, and [the length of the marked line before drying-the length of the marked line after drying] / the length of the marked line before drying] × 100 The shrinkage percentage was obtained from (%). Table 2 shows the results.

3. Measurement of Physical Properties of Polyurethane Porous Material The polyurethane porous material obtained through the drying step was measured for hardness (Asker C type), apparent density, tensile strength, and elongation rate. Table 2 shows the results. The hardness was measured using an Asker C type hardness meter (Polymer Keiki Co., Ltd.), the apparent density was measured according to JIS K 7222, and the tensile strength and elongation were both measured according to JIS K 6440-5.

(Comparative Example 1)
It carried out similarly to said "(Examples 1-4)" except having replaced with the liquid mixture which consists of water and DMF, and having used only DMF. Table 1 shows the mixing ratio of each component, and Table 2 shows the results.
(Comparative Example 2)
Except having used the mixture and liquid mixture which are shown in Table 1, it carried out similarly to said "(Examples 1-4)". Table 1 shows the mixing ratio of each component, and Table 2 shows the results.
(Comparative Example 3)
Except that the kneaded composition was prepared without using the mixed solution, the same procedure as in the “(Examples 1 to 4)” was performed. Table 1 shows the mixing ratio of each component, and Table 2 shows the results.
(Comparative Example 4)
Except that calcium chloride dihydrate (average particle size: 20 μm) was used in place of anhydrous calcium chloride and water, and that only DMF was used in place of the mixed solution of water and DMF, the above “(implementation) Example 1-4) ”. Table 1 shows the mixing ratio of each component, and Table 2 shows the results.

The shrinkage rates of Examples 1 to 4 were single digits in both the vertical direction and the horizontal direction, and good results were shown. On the other hand, in Comparative Example 3, the shrinkage ratios in the vertical and horizontal directions were both 10% or more and did not show good shrinkage ratios. From this result, in order to make the shrinkage ratio of the polyurethane porous body less than 10% in the drying step, a mixture of a polyurethane resin solution, DMF and anhydrous calcium chloride, and a mixture of water and DMF are kneaded and kneaded. It turned out that the process of obtaining a thing was required. Furthermore, in the comparative example 3, the obtained polyurethane porous body became hard in a solid state, and physical properties could not be measured.
Next, in Comparative Example 1, as in Comparative Example 3, both the vertical and horizontal shrinkage ratios were 10% or more, and good shrinkage ratios were not exhibited. Further, in Comparative Example 1, as in Comparative Example 3, the polyurethane porous body itself could be produced, but it became solid and hard and the commercial value was low.
And although the mixed liquid which consists of water and DMF was used in the comparative example 2, the kneading | mixing composition became loose-shaped and the molded article of the polyurethane porous body was not able to be manufactured.
From the above results, water / DMF = 5/25 to 20/10 is preferable as the weight ratio of the mixed solution of water and DMF in order to make the shrinkage ratio of the polyurethane porous body less than 10% in the drying step. It's a range.
Comparative Example 4 is a system using calcium chloride dihydrate in place of anhydrous calcium chloride and water, but both the shrinkage ratios in the vertical and horizontal directions were 15% or more, indicating a good shrinkage ratio. There wasn't.

(Examples 5 to 13)
Except having used the mixture and liquid mixture which consist of a mixture ratio shown in Table 1, it carried out like said "(Examples 1-4)". Table 3 shows the results.
(Comparative Examples 5-7)
It carried out similarly to said "(Examples 5-13)" except having replaced with the liquid mixture which consists of water and DMF, and having used only DMF. Table 1 shows the mixing ratio of each component, and Table 3 shows the results.

  In Examples 5 to 13, the shrinkage ratios in the vertical direction and the horizontal direction were both less than 10%, indicating good shrinkage ratios. On the other hand, in Comparative Examples 5 to 7 in which only DMF was used in place of the mixed solution composed of water and DMF, both the vertical and horizontal shrinkage ratios were 10% or more, and good shrinkage ratios were not exhibited. From these results, it was found that even when the blending ratio of the kneaded composition was changed for each component, the same results as the “(Examples 1 to 4)” were obtained.

(Examples 14 to 17)
Except having used anhydrous calcium chloride which has the average particle diameter shown in the margin of Table 4, and having used the mixture and liquid mixture which consist of a mixture ratio shown in Table 4, said "(Examples 1-4)" and The same was done. Table 5 shows the results.
(Comparative Examples 8-9)
It carried out similarly to said "(Examples 14-17)" except having replaced with the liquid mixture consisting of water and DMF, and having used only DMF. Table 4 shows the mixing ratio of each component, and Table 5 shows the results.

  In Examples 14 to 17, both the shrinkage ratios in the vertical direction and the horizontal direction were less than 10%, indicating good shrinkage ratios. Comparing the shrinkage rates of Examples 14 and 16 and Example 1, Examples 14 and 16 were smaller than Example 1. From this result, it was found that the shrinkage rate tends to decrease as the average particle size of anhydrous calcium chloride increases. Similar results were obtained when the shrinkage rates of Examples 15 and 17 and Example 4 were compared.

(Comparative Examples 10-13)
Except that sodium chloride (average particle size: 10 μm or 30 μm) was used in place of anhydrous calcium chloride and that the kneaded composition was prepared with the blending ratio of each component shown in Table 4, the above “(Example 1 to 4) ". Table 5 shows the results.

  From the results of Comparative Examples 10 to 13, in the system using sodium chloride in place of anhydrous calcium chloride, in the case of Comparative Example 11, when a mixed liquid of water and DMF was added and kneaded, the shrinkage ratio compared to Comparative Example 10 was Although it is small, the shrinkage rate in the vertical direction is around 15%, and it was found that the shrinkage rate is not good. Furthermore, it was found from comparison between Comparative Examples 12 and 13 that the shrinkage rate may not change even when a mixed solution of water and DMF is added and kneaded.

  INDUSTRIAL APPLICABILITY The present invention is widely applicable as a method for producing a polyurethane porous body that has a small shrinkage rate in a drying process and can stably produce a product as designed.

Claims (6)

  A step of kneading a mixture containing a polyurethane resin, a solvent and anhydrous calcium chloride, and a mixture of water / solvent having a weight ratio of water / solvent = 10/90 to 75/25 to obtain a kneaded composition, the kneaded composition A method for producing a polyurethane porous body, comprising a step of molding a product, a step of solidifying the obtained molded body, and a step of removing water from the solidified molded body by extracting anhydrous calcium chloride, followed by drying.   The manufacturing method of the polyurethane porous body of Claim 1 whose average particle diameter of an anhydrous calcium chloride is 100 micrometers or less.   The manufacturing method of the polyurethane porous body of Claim 2 whose content of the polyurethane resin in a kneading composition is 20 weight% or less.   Use for cosmetic sponge, cushion material, OA equipment roller, water absorption roller, liquid draining roller, conductive roller, ink roller, water absorption sheet, swab, medical sponge, head rubber for chemical application, penetrating mark, brush pen or filter, The manufacturing method of the polyurethane porous body of Claim 3.   A polyurethane porous body produced by the method according to claim 3.   Use for cosmetic sponge, cushion material, OA equipment roller, water absorption roller, liquid draining roller, conductive roller, ink roller, water absorption sheet, swab, medical sponge, head rubber for chemical application, penetrating mark, brush pen or filter, The polyurethane porous body according to claim 5.