JPS62121738A - Porous high-molecular article - Google Patents

Abstract

PURPOSE:To provide the titled porous article which has a high water absorption rate and excellent water retention, touch when wetted, flexibility and elasticity and can be rapidly softened by wetting even after drying, by reacting a specified PVA polymer with an aldehyde and an acid. CONSTITUTION:A vinyl ester such as vinyl acetate is copolymerized with a monomer of formula I or II (wherein R<1>-R<3> are each H, CH3; R<4> is CH3, C2H5) and the copolymer is saponified to obtain a PVA copolymer (A) composed of 1-50mol% of a structural unit of formula III. The component A, 80-300mol% (based on the amount of the component A) of an aldehyde (B) (e.g., acetaldehyde) and 50-200mol% (based on the amount of the component B) of an acid (C) (e.g., hydrochloric acid) are dissolved or dispersed in water and heated in the presence of a cell forming aid (D) (e.g., processed starch) at 30-80 deg.C for 5-50hr to carry out a reaction to such an extent that the degree of acetalization is 50-85%. The reaction product is washed with (hot) water to remove the components B, C and D.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention is directed to a porous polymer which is formed by reacting an aldehyde and an acid to a polyvinyl alcohol copolymer containing the following structural units. Concerning substance.

Kaya H (Here, R1, R2, and R3 each represent H or CH3 groups.) B. Conventional technology Conventionally, pore-forming aids such as starch were added to polyvinyl alcohol, and aldehyde and acid were made to react. The poly and nyl acetal porous material has continuous pores,
It has many characteristics such as high porosity, high hydrophilicity due to the OH group in the molecule, and high mechanical strength of the porous body and excellent chemical resistance.
Various filters, water-based makeup sponges, sponge grindstones,
It is widely used for water absorption and dehydration rollers, kitchen and bath sponges, etc.

However, although porous bodies obtained using ordinary polyvinyl alcohol have good feel, flexibility, and elasticity when wet, they have poor feel and become rigid when dry. Once dried, it takes a considerable amount of time and effort to moisten and soften it.

In order to overcome these drawbacks, we have tried to improve water absorption and feel by adding substances other than polyvinyl alcohol, such as bulb powder, cotton linters, vinylon fibers, and sponge powder; After-treating the material with an aqueous solution of a water-absorbing substance such as a surfactant, glycerin, or polyethylene glycol to give it water-absorbing properties, ■ Adding a highly water-absorbing resin during manufacturing to increase the water absorption rate, ■ Adding to polyvinyl alcohol. Attempts have been made to increase the water absorption rate by using modified polyvinyl alcohol copolymerized with hydrophilic monomers, but method (1) results in a decrease in the physical properties of the resulting porous body;
In case 2, only a temporary effect can be obtained as the water-absorbing substance gradually falls off, and in case 2 and 3, although improvements have been made, it is still not sufficient, and no effective measures have been found to solve the above problems. The current situation is that this is not the case.

C1 Problems to be Solved by the Invention Overcoming the above-mentioned drawbacks of conventional porous materials, it has good feel, flexibility, and elasticity when wet, and is quick to dry once dried. The purpose of this invention is to provide a porous polymer material that softens when wet.

q Rounding means to solve the problem As a result of intensive studies, the present inventors have developed a polyvinyl alcohol copolymer containing the following structural unit A as a polyvinyl alcohol copolymer (hereinafter referred to as PVA). A porous polymer material formed by reacting an aldehyde with an acid R1♂H (where R1, g2, and R3 each represent a H or CH3 group) solves the above problems. The inventors have discovered that this is an excellent porous material that can be obtained, and have completed the present invention.

The polyvinyl alcohol β alcohol copolymer (hereinafter abbreviated as the PVA copolymer of the present invention) containing the following structural unit A of the present invention will be explained.

OH (wherein R1, 12, g3 are H or CH3 groups, respectively) OH0H OH It controls the water absorption and water retention properties of the molecular porous material, and if it is less than 1 molar, the effect is extremely small, and if it is introduced in an amount greater than 50 molar, the degree of polymerization will be greatly reduced. Preferably, the degree of polymerization is 100 or more.
If it is less than 000, it can be used without any problems, but
In particular, when the degree of polymerization is low (300 degrees or higher), it is often preferable to use it in combination with ordinary PVA having a high degree of polymerization. Further, it can be used if the degree of saponification is 60 molar or more, preferably 70 molar or more.

The PVA copolymer of the present invention is formed by a general formula (R1, R2, R3 each represents H or a CHs group, and R4 represents a CHs group or a C2M5 group) with a vinyl ester such as vinyl acetate. Obtained by copolymerizing and saponifying monomers. As such a monomer, C)is
CHs&.

etc., but CHz=CH-CH20COCHs and CH, which are well copolymerized with vinyl esters such as vinyl acetate,
z=Hs (2) CH-C-OH is preferably used.

Furthermore, when copolymerizing a monomer represented by the above general formula with a vinyl ester such as vinyl acetate, a small amount of a monomer that can be copolymerized with these may be copolymerized as long as the object of the present invention is not impaired. These monomers include α-olefins such as ethylene, propylene, and isobutyne, acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, maleic anhydride or its salts or alkyl esters, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N,
Examples include, but are not limited to, N-dimethylacrylamide, alkyl vinyl ethers, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, and vinyl persate.

The porous polymer of the present invention is prepared by reacting the PVA copolymer of the present invention with an aldehyde and an acid in the presence of a pore-forming aid. Those used in the production of conventional porous bodies can be used as they are.

For example, examples of pore-forming aids include raw starch, various modified starches, starch, surfactants, pulp powder, inorganic and organic blowing agents, etc.Aldehydes include formaldehyde, acetaldehyde, butyraldehyde, 2- Aliphatic aldehydes such as ethylhexylaldehyde or aromatic aldehydes such as pendualdehyde are used, and examples of acids include hydrochloric acid, sulfuric acid, and acetic acid.

The porous body can be manufactured in the same manner as conventional ones. The amount of aldehyde used is about 80 to 300 molti based on the PVA copolymer, and the amount of acid is about 5 molti based on the aldehyde.
It is preferable to use about 0 to 200 molti. The reaction involves the PVA copolymer of the present invention, a pore-forming aid, an aldehyde,
and an aqueous solution or dispersion of the acid at a temperature of 30 to 80° C. for 5 to 50 hours. After the acetalization reaction is completed, the reaction product is washed with water or hot water to remove the pore-forming aid and unreacted aldehyde, acid, etc. to obtain the desired polymeric porous material.Acetalization of a porous material The degree is an important factor that affects the physical properties of the porous body, and varies depending on the S type and amount of the PVA copolymer used in the present invention, but is 50 to 85, preferably 55 to 80.
A good porous body can be obtained within this range.

In the present invention, it is also possible to add and mix other substances within a range that does not impede the performance aimed at by the present invention. Examples of these include ordinary polyvinyl alcohol, various modified polyvinyl alcohols, and hydroxyethyl cellulose. Furthermore, pipe powder, cotton linter, vinylon fiber, sponge powder, etc. may be used as an additive. The porous polymer material characterized by the following features as compared to the porous material obtained using conventional ordinary PVA-based polymers: 0(1) The water absorption rate of the porous material is extremely high. , water retention is also good.

(2) It has great flexibility when hydrated and has a smooth texture.

These characteristics can only be obtained by using a polyvinyl alcohol copolymer containing the structural unit A as the substrate of the porous polymer, and this structural unit has good acid resistance and alkali resistance. Therefore, the performance does not deteriorate while the porous body is used.

The porous polymer material obtained by the present invention has excellent water absorption properties, especially easy wettability, good elasticity, flexibility,
Because of its tactile feel, it is suitable for use in aqueous cosmetic puffs, bath sponges, synthetic chamois, sponge cake 7, car wash sponges, water absorption rollers, kitchen sponges, various filters, sponge grindstones, and the like.

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto.

Note that parts and weights are parts by weight unless otherwise specified.
It means i 俤.

Example 1 40 parts of a polyvinyl alcohol (hereinafter abbreviated as FPVA) copolymer with δH and a saponification degree of 885 and a molar association degree of 600 and PVA-217 (average degree of polymerization 1700 and saponification degree 881)
500 parts of an aqueous solution containing 20 parts of molar ratio was prepared. To this was added 30 parts of potato starch dispersed in water to make 200 parts, and the mixture was kept at 70°C for 10 minutes with stirring to gelatinize the starch.

Cool this to 50°C, add 100 parts of 37-yellow formalin, and
Mix 100 parts of 0% sulfuric acid and add water to bring the total volume to 1000 parts.
The mixture was thoroughly mixed in portions at 45°C. After that, it was cast into a glass container and reacted at 70°C for 12 hours. The reaction product was washed with warm water to obtain a porous body.

Table 1 shows the properties of the obtained porous body.

Example 2 A porous body was obtained in the same manner as in Example 1, except that 60 parts of a PVA-based copolymer containing 5.4 mol of H, a saponification degree of 96.5 mol, and a polymerization degree of 900 was used. Table 1 shows the properties of the obtained porous body.

Example 3)' As VA, structure 441st position A (!: L Te(-
40 parts of a PVA-based copolymer containing 9.8 mol of cHz-CH+HaC-C-CHa H, a saponification degree of 89.0 mol, and a polymerization degree of 500 and PVA-2172.
A porous body was obtained in the same manner as in Example 1 except that 0 part was used. Table 1 shows the properties of the porous material obtained.

Comparative Example I A porous body was obtained in the same manner as in Example 1 except that 1760 parts of PVA-2 was used as VA. Table 1 shows the properties of the obtained porous body.

Table 1 (Note 1) Water absorption rate (paper): 2cm x 2m x 10cm
When a dried sample cut into pieces (dried at 80°C for 24 hours) was held vertically in water at 20°C with the bottom submerged for 2 hours, water flowed through the sample until it reached a height of 3 crn above the water surface. expressed in hours.

(Note 2) Wetting speed e (paper): A dried sample (dried at 80℃ for 24 hours) cut into 10 (7) pieces vertically and horizontally and 2C7n thick is gently floated on the surface of water at 20℃. It is expressed as the time it takes to sink below the water surface.

(Note 3) Water retention (%): Weight after allowing the sample to retain twice its bone dry weight of water and leaving it in a constant temperature and humidity chamber at 30°C and 50% RH for 7 hours (wet type f ) was calculated using the following formula.

Applicant Kurashi Co., Ltd.

Claims (1)

[Scope of Claims] (1) A porous polymer material formed by reacting an aldehyde and an acid with a polyvinyl alcohol copolymer containing the following structural unit A. A; ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, R^1, R^2, R^3 are H or C, respectively.
Represents H_3 groups. ) (2) The porous polymer body according to claim 1, wherein R^1 = R^2 = R^3 = H. (8) The porous polymer body according to claim 1, wherein R^1 = H and R^2 = R^3 = CH_3.