JPS61130349A - High-molecular porous body - Google Patents

Abstract

PURPOSE:To provide the titled porous body having open cells, high porosity, and excellent water absorption, water retention, chemical resistance and mechanical strength, by reacting an aldehyde and an acid with a particular block copolymer having a PVA polymer as one component. CONSTITUTION:A water-soluble or -dispersible block copolymer (A) contg. a PVA polymer with a vinyl alcohol unit of 20mol% or more and a degree of polymn. of 10 or above (a) and other component polymer such as a water-soluble or -swellable polymer [e.g., a water-soluble polymer with a monomer unit of (meth)acrylic acid (metal salt) and the like] or a polymer with a m.p. lower than ordinary temp. (e.g., a polymer contg. a monomer unit such as C2H4 or C3H6) (b) in a wt. ratio of 0.1<=a/b<=50, 80-300 mol%, based on the PVA polymer moiety of the component A, aldehyde such as HCHO (B), and 50-200mol%, based on the component C, acid such as sulfuric acid (C) are heated at 30-80 deg.C for 5-50hr in the presence of a pore forming aid such as starch for acetal formation, and the reaction product is washed with (hot) water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a porous polymer material 1c formed by reacting aldehyde and acid with a water-soluble or water-dispersible block copolymer containing a polyvinyl alcohol polymer as one component. related.

Polyvinyl acetal porous material obtained by adding pore-forming aids such as starch to polyvinyl alcohol and allowing aldehyde and acid to react has continuous pores, high porosity, and OH groups in the molecule. The porous material has many characteristics such as high hydrophilicity, high mechanical strength and excellent chemical resistance, and is used in various filters, water-based cosmetic sponges, sponge grindstones, water absorption,
It is widely used for dehydration rollers, kitchen and bath sponges, etc.

B. Prior art A porous body obtained using ordinary polyvinyl alcohol is
When wet, it has a good feel, flexibility, and elasticity, but when dry, it has a poor feel and becomes rigid. Also, once it dries, it takes a lot of time and effort to wet 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;
The water-absorbing substance gradually falls off, so only a temporary effect can be obtained.■.

Although improvements have been made to (2), it is still not sufficient, and currently no effective measures have been found to solve the above problems.

C1 Problems to be Solved by the Invention The present invention overcomes the drawbacks of conventional porous materials as described above, and has good feel, flexibility, and elasticity when wet, as well as being quick to dry once dried. It is an object of the present invention to provide a porous body that softens when wet, and furthermore, a porous body that retains its soft properties even when dry compared to conventional porous bodies.

Means for Solving Problem D1 As a result of intensive studies, the present inventors have developed a water-soluble or water-dispersible block copolymer containing a polyvinyl alcohol polymer (hereinafter referred to as PVA polymer) as a component. The polymeric porous material formed by the action of aldehyde and acid solves the various problems mentioned above by appropriately selecting other component polymers other than the PVA-based polymer of the block copolymer. The inventors have discovered that this porous material is an excellent porous material that can be used for various purposes, and have completed the present invention.

The polymeric porous material formed by reacting 1-aldehyde and an acid with a water-soluble or water-dispersible block copolymer containing the PVA-based polymer of the present invention as one component can be obtained by using the PVA of the block copolymer used. It has various physical properties depending on the type and content of other component polymers other than the system polymer.

Other component polymers other than the PVA-based polymer of the block copolymer are water-soluble or water-swellable, or other component polymers that have been partially or wholly hydrolyzed under acetalization conditions are water-soluble. Or, if it is water-swellable, it becomes a porous body that easily absorbs water, which is the object of the present invention. Examples of such other component polymers include (meth)acrylic acid and its metal salts and ammonium salts, (meth)acrylamide, N
, N'-dimethylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid and its metal salts, 3-
(methaneacrylamidopropyltrimethylammonium chloride.

diallyldimethylammonium chloride, itaconic acid,
Maleic acid %7 A water-soluble polymer containing monomer units such as malic acid and metal salts thereof is partially or entirely hydrolyzed during acetalization and becomes water-soluble or water-swellable. (
meth) methyl acrylate, (ethyl methane acrylate,
Butyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethyl hydroxy (meth)acrylate, dimethylaminoethyl (meth)acrylate, etc.
Examples include polymers containing meth)acrylic acid esters, and polymers containing vinyl esters such as vinyl acetate and vinyl propionate.

Furthermore, polyoxyethylene and water-soluble or water-swellable polyoxyalkylene containing oxyethylene units,
Further examples include water-based polycrethane and water-based polyester.

t-fi: When the softening point of the other component polymer is sufficiently lower than normal temperature, which is the normal use temperature of the porous body of the present invention, it can be used even during drying, which is a further object of the present invention. A flexible porous polymer body is obtained.

Examples of such other component polymers include polymers containing monomer units such as butadiene, isoprene, ethylene, propylene, isobutyne, oxyethylene, oxypropylene, oxytetramethylene, (meth)acrylic acid ester, etc. .

The weight ratio of the PVA-based polymer and other component polymers of these block copolymers is determined in order to achieve the desired performance of the present invention and the physical properties such as feel, mechanical strength, and chemical resistance of the resulting porous material. From the relationship, 0, ]≦(PVA polymer)/(other component polymer)≦50
is preferable, and more preferably, 0゜2≦(PVA polymer)/(other component polymer)≦20
It is.

In addition, the PVA-based polymer referred to in the present invention refers to a polymer containing vinyl alcohol units of 20 mol or more, preferably H50 mol or more, more preferably 70 mol or more, and other monomer components. Examples include vinyl acetate, vinyl formate, vinyl propionate, vinyl persate, polyethylene, propylene, (meth)acrylic acid and its salts, itaconic acid, maleic acid, fumaric acid, and their salts, 2-acrylamide. 2-methyl 7
'O-panesulfonic acid and its salts, (meth)acrylamide butyltrimethylammonium chloride, etc. may be included. The degree of polymerization is 10 or more, preferably 100 or more, more preferably 200 or more and 300 or more.
There is no particular restriction as long as it is within the range of 0 or less.

The water-soluble or water-dispersible block copolymer containing the PVA polymer of the present invention as one component can be obtained, for example, by the following method, but of course those synthesized by other methods can also be used. Examples include: (1) a method of saponifying a polyvinyl acetate polymer obtained by polymerizing a monomer such as vinyl acetate in the presence of other component polymers having a mercapto group at the end; A method of polymerizing monomers constituting other component polymers in the presence of a PvA polymer,
This is a method in which a PVA-based polymer having a mercapto group at its end is added to a polymer having another component having a reactive group having a high reactivity with a mercapto group, such as a double bond, at its end.

Among these, methods (1) and (2) are suitable when the other component polymer is a polymer obtained by condensation polymerization, and method (2) is suitable when the other component polymer is obtained by radical polymerization.

The porous polymer material of the present invention is produced by treating a water-soluble or water-dispersible block copolymer containing a PVA polymer as one component with an aldehyde and an acid, usually in the presence of a pore-forming aid. However, the pore-forming aid, aldehyde and acid used in conventional production of porous bodies can be used as they are.

Examples of pore-forming aids include raw starch, various modified starches, dextrose, surfactants, pulp powder, and inorganic and organic blowing agents.

Examples of aldehydes include aliphatic aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, and 2-ethylhexylaldehyde, and aromatic aldehydes such as benzaldehyde; examples of acids include hydrochloric acid,
Examples include sulfuric acid and acetic acid.

The porous body can be manufactured in the same manner as conventional ones. The amount of aldehyde used is the PV of the block copolymer.
It is preferable to use about 80 to 300 molti with respect to the A-based polymer part, and about 50 to 200 molti with respect to the aldehyde for the acid.
An aqueous solution or dispersion of an aldehyde and an acid is added to
This is carried out by heating at a temperature of 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 porous polymer. The degree of acetalization of the porous material is an important factor that influences the physical properties of the porous material, and varies depending on the type and amount of the block copolymer used in the present invention, but is preferably 50 to 85%, preferably 55 to 85%. A good porous body can be obtained within the range of 80 inches.

In addition, in the present invention, a PVA-based polymer is used as one component,
It is also possible to use two or more types of water-soluble or water-dispersible block copolymers in combination, and furthermore, other substances may be added and mixed within a range that does not impede the performance aimed at by the present invention. It is also possible to use Examples of these include ordinary vinyl alcohol, various modified polyvinyl alcohols, and hydroxyethyl cellulose.

Furthermore, pulp powder, cotton linter, vinylon fiber, sponge powder, etc. may be added.

80 Actions and Effects of the Invention A polymeric porous material formed by reacting an aldehyde and an acid with a water-soluble or water-dispersible block copolymer containing the PVA-based polymer of the present invention as one component is different from the conventional one. It has the following characteristics compared to porous bodies obtained using ordinary PVA-based polymers.

(1) The other component polymers of the block copolymer are water-soluble or water-swellable, or the other component polymers after being partially or wholly hydrolyzed under acetalization conditions are water-soluble or water-swellable. When the porous material is water-swellable, the water absorption rate of the porous material is extremely high, and the porous material also has good water retention properties.

(2) If the softening point of the other component polymers of the block copolymer is sufficiently lower than room temperature, which is the normal operating temperature of the porous body of the present invention, the porous body will remain flexible even when dry. can get.

(3) When the block copolymer and the pore-forming aid have good compatibility, for example, when the other component polymer of the block copolymer is a polyacrylamide polymer and the pore-forming aid is a starch. By appropriately selecting the weight ratio of each polymer component of the block copolymer and the ratio of the block copolymer to the pore-forming aid, a porous material having extremely fine pores can be obtained. .

These characteristics can only be obtained by using a block copolymer containing a PVA polymer as one component as the base of the porous material. If other components other than the polymer are simply mixed together, a porous material of good quality cannot be obtained due to poor compatibility between the two, and even if porous material is obtained, the polymer may be a porous substrate. Because there is no chemical bond with
The object of the present invention cannot be achieved because it falls off during washing with water or hot water or while using a porous material.

The porous polymer obtained by the present invention has excellent water absorbency, easy wettability with 4fFK water, and good elasticity, flexibility, and feel, so it can be used in aqueous cosmetic puffs, bath sponges, synthetic chamois, etc. It is suitably used for sponge whetstones, car wash sponges, water absorption rollers, kitchen sponges, various filters, sponge whetstones, etc.

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

Note that parts and esFi mean parts by weight and % by weight unless otherwise specified.

Examples 1 to 8 An aqueous solution containing block copolymer 602 shown in Table 1 was
01111 adjusted. 30 pieces of potato starch in this? A dispersion of 200 d in water was added and the mixture was kept at 70°C for 10 minutes with stirring to gelatinize the starch. 50 of this
Cool to 37 °C, 5
Mix 100d'e of 0% sulfuric acid and add water to bring the total volume to 1!
The mixture was thoroughly mixed 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 3 shows the properties of the obtained porous body.
Shown below.

Comparative Examples 1 to 4 Porous bodies were prepared in the same manner as in Examples using the PVA-based polymers and other polymers shown in Table 2.

Table 3 shows the properties of the obtained porous body.

-□ 1/-' Table 1 (Note 1) P'/41); ]i (combined [575, f
f/v conversion [98,7 mol 5PvA (2) i heavy 4r
K 1020 , chelation [96.2 mol g.

Carboxyl modified (degree of modification 2 mol) PVA (81; Polymerization 11400.ff/v ([99
, 1 mol 96P VA(4) i polymerization L 450 ,
/'/ Chemical L 94-3 mol% - Carboxyl modification (degree of modification 5 mol%) PAA i Polyacrylic acid P (AAm/Nri; Random copolymer of acrylamide and acrylic acid P(L)At)MAC) i Polydiallyldimethylammonium chloride P (2-MEA/AA) i Random copolymer of 2-methoxyethyl acrylate and acrylic acid P (DMAAm/MAPTAC); Random copolymer of dimethylacrylamide and methacrylamide propyltrimethylammonium chloride PEO; Polyethylene oquinide P (VAc/Et); Random copolymer of vinyl acetate and ethylene P (Bd/St); Random copolymer of butadiene and styrene (Note 2) Numbers in parentheses represent weight ratios.

(Note 1) Water absorption rate (seconds): 2 CIl X 2 a
Dry samples (dried at 80°C for 24 hours) cut into pieces of n
11E When the sample is held vertically so as to be submerged, it is expressed as the time it takes for water to reach a height of 3 (:l11) above the water surface.

(Note 2) Wetting speed (excerpt): 1 OcIIL 1 each for vertical and horizontal directions
A dried sample (dried at 80°C for 24 hours) cut to a thickness of 21°C is floated on the surface of water at 20°C, and expressed as the time it takes for the sample to submerge under the water surface.

(Note 3) Flexibility: Flexibility when wet is measured at a temperature of 20°C and a water retention rate of 100% (a state in which water is retained in an amount equal to the dry weight), and flexibility when dried is measured at a temperature of 20°C (80°C). at 24
A sensory test was carried out to evaluate the condition in which the temperature and humidity were controlled at a temperature of 20° C. and a humidity of 65%.

(○) Flexible (Δ) Slightly flexible (×) Rigid (Note 4) Water retention (→: After the sample retains twice its absolute dry weight of water, it is kept at a constant temperature and humidity of 30°C and 50% RH. Calculate the weight after leaving it in the container for 7 hours (humidity @t≧) and find it.

Claims (3)

[Claims] (1) Contains polyvinyl alcohol polymer as one component,
A porous polymer material formed by reacting a water-soluble or water-dispersible block copolymer with an aldehyde and an acid. (2) The block copolymer is a water-soluble block copolymer containing a polyvinyl alcohol-based polymer as one component and a water-soluble or water-swellable polymer as another component. Molecular porous material. (3) Claims in which the block copolymer is a water-soluble or water-dispersible block copolymer containing a polyvinyl alcohol-based polymer as one component and a polymer with a softening point lower than room temperature as the other component. 2. The porous polymer body according to item 1.