JPH0446981B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a hydrophilized crosslinked polyolefin open cell and a method for producing the same. More specifically, it is a hydrophilic crosslinked polyolefin open cell, characterized in that an acetalized product of water-insolubilized modified polyvinyl alcohol is attached and included on the surface and within the open cells of the crosslinked polyolefin open cell, and a method for producing the same.

[Conventional technology]

BACKGROUND ART Conventionally, hydrophilic materials such as cellulose, cellulose derivatives, and gelatin have been put into practical use as filter media, puffs for cosmetics, water-retaining materials for pottery, and the like. Alternatively, a porous sintered body obtained by adding and mixing a hydrophilic substance to a hydrophobic synthetic resin powder such as a fluororesin, polyethylene, polypropylene, or polyimide and sintering the mixture, i.e., a porous sintered body that has undergone hydrophilic treatment Sintered bodies are commonly used as membrane materials for membrane filtration, dialysis, battery separators, etc.

[Problem to be solved by the invention]

However, although hydrophilic materials using cellulose, cellulose derivatives, gelatin, etc. have a relatively good texture, they are insufficient in weather resistance, chemical resistance, and mechanical strength. In addition, although the hydrophilic porous sintered body has sufficient weather resistance, chemical resistance, and mechanical strength, it is hard and lacks the elastic feel of human skin when wet or hydrated. Therefore, its uses are limited and it cannot be used as a household water absorbing material. In addition, due to its low porosity, it has a poor water retention capacity and cannot be used as a material for water retention materials for gardening. Therefore, the object of the present invention is to completely eliminate the above-mentioned drawbacks, maintain excellent hydrophilicity, water absorption and water retention, and have a feel similar to human skin when wet or hydrated. An object of the present invention is to provide a hydrophilized crosslinked polyolefin open cell foam having sufficient weather resistance, chemical resistance, and mechanical strength, and a method for producing the same.

[Means to solve the problem]

In order to achieve the above object, the hydrophilic crosslinked polyolefin open cell according to the present invention is characterized in that an acerated product of modified polyvinyl alcohol is attached and included on the surface and within the open cells of the crosslinked polyolefin open cell. . In the present invention, the modified polyvinyl alcohol is, for example, polyvinyl alcohol modified with an unsaturated carboxylic acid or a derivative thereof and having a high water absorption capacity. The method for producing a hydrophilized crosslinked open-cell polyolefin foam of the present invention is as follows: (1) An open-cell polyolefin foam is impregnated with an aqueous solution of modified polyvinyl alcohol containing an acid and an aldehyde, and then the modified polyvinyl alcohol is subjected to an acetalization reaction. A method for producing a hydrophilized crosslinked polyolefin open cell foam, which comprises adhering and incorporating an acetalized product of modified polyvinyl alcohol on the surface of the foam and within the open cells. (2) A cross-linked polyolefin open cell is impregnated with an aqueous solution of modified polyvinyl alcohol to which an acid and an aldehyde have been added, and then the acetalization reaction of the modified polyvinyl alcohol is carried out to form modified polyvinyl alcohol on the surface of the foam and within the open cells. 1. A method for producing a hydrophilized crosslinked polyolefin open-cell foam, which comprises adhering and incorporating an acetalized product, and further contacting the foam after the acetalization reaction with an alkaline aqueous solution. It is. In the present invention, the base material of the open cell used for hydrophilization treatment includes, for example, polyethylene, ethylene-vinyl acetate copolymer, poly-1,2-butadiene, ethylene-propylene copolymer, ethylene-butene copolymer. Combined with ethylene content 45% by weight
copolymers with methyl, ethyl, propyl, and butyl acrylates or methacrylates, or chlorinated versions of these (up to 60% chlorine content), or two of these.
A mixture of more than one kind of these or a mixture of these with polypropylene having an atactic or isotactic structure can be used. In the present invention, it preferably has a uniform cell structure, a foaming ratio of 5 to 70%, and an open cell ratio of 70%.
(Values measured according to ASTM D 1940-62T,
The same applies hereinafter) A crosslinked polyolefin open cell having the above is employed. Particularly preferable materials in terms of texture, weather resistance, chemical resistance, mechanical strength, etc. are, for example, crosslinked polyolefin open-cell foam manufactured by Sanwa Kako Co., Ltd.
Opcel LC-300 #1s, Opcel LC-300
#1, Opcel LC-300 #2, Opcel LC-300
#3 etc. In the present invention, there is no particular limitation on the amount of acetalized modified polyvinyl alcohol adhered to and contained within the open cells and on the surface of the crosslinked polyolefin open cells. The acetal compound may adhere to the entire surface and fill the open cells, or it may adhere to the surface and the open cells moderately and microscopically. Thereby, the object of the present invention can be achieved. The open-cell hydrophilized crosslinked polyolefin foam according to the present invention is generally harder and less elastic when dry than the foam used, although it depends on the amount of the acetalized product attached and included. On the other hand, when wet or hydrated, it exhibits an elastic texture similar to that of human skin, and is extremely soft to the touch. In the production method of the present invention, as a method for making an open cell hydrophilic, the open cell to be used is first immersed in an acetalization liquid, and the open cell is pressed to remove air within the open cell. Next, the pressed open cell is relaxed to allow the acetalization liquid to enter the open cell, and the process of pressing and relaxing the open cell is repeated while the open cell is immersed in the acetalization liquid. . Alternatively, in a closed system, after degassing the air in the open cells by degassing under reduced pressure (or while degassing), the acetalization liquid is injected into the closed system to cause the acetalization liquid to enter the open cells. Alternatively, after the air in the open cells is degassed by reduced pressure, the open cells are immersed in the acetalization liquid (which may be pressurized). Alternatively, the open cells are impregnated with the acetalization liquid by employing an impregnation method such as immersing the open cells in the acetalization liquid and applying ultrasonic waves. In this case, since the acetalization liquid is viscous, in the case of open cells having low rebound resilience (restoring property), the acetalization liquid does not quickly and uniformly penetrate into the open cells. Moreover, the open cell membrane is adhered by the acetalization liquid, causing the open cell membrane to shrink extremely. Alternatively, it may shrink or deform locally. Therefore, it is necessary to appropriately select the viscosity of the acetalization liquid used and to impregnate the cell with the acetalization liquid so as to maintain the original shape of the open cell as much as possible. If the open cell to be impregnated with the acetalization liquid is extremely shrunk, locally shrunk, or deformed, even in the acetalization reaction treatment, water washing treatment, or alkaline aqueous solution treatment described below, Contraction and deformation are maintained as they are. As a result, the resulting hydrophilic crosslinked polyolefin open cell has a reduced size and yield, resulting in a loss in cost and non-uniform quality, making it impossible to obtain a good hydrophilic crosslinked polyolefin open cell. Next, the open cell impregnated with the acetalization liquid is subjected to an acetalization reaction, and an acetalized product of water-insoluble modified polyvinyl alcohol is formed on the surface of the open cell and within the open cell. For example, a reaction temperature of 30 to 80° C. is used for several hours to several tens of hours. The modified polyvinyl alcohol used in the production method of the present invention includes unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, etc.) or derivatives thereof (partial or complete alkyl esters and salts thereof). Examples include saponified copolymers (saponification degree: 50 mol% or more, preferably 80 mol% or more) of copolymers of vinyl acetate and (anhydrides, nitriles, amides, etc.) and vinyl acetate. To specifically enumerate these, for example, Gosenal T-330, which is a modified polyvinyl alcohol manufactured by Nippon Gohsen Kagaku Kogyo Co., Ltd.;
330H, Gosenal T-350, etc. Then, an acetalization liquid is prepared using the modified polyvinyl alcohol. The concentration of the modified polyvinyl alcohol component in the acetalization liquid depends on the degree of rebound elasticity of the open cell to be hydrophilized (i.e., the stiffness of the open cell,
Restorability), the desired degree of rebound resilience of the resulting hydrophilized open-celled material, the degree of hydrophilization, etc., are selected as appropriate. Specifically, it is usually 0.3 to 7% (weight%,
It is particularly preferable to select from the range of (the same applies hereinafter) from the viewpoint of ease of penetration into open cells or avoidance of shrinkage or deformation of open cells. Examples of the acid include hydrochloric acid, phosphoric acid, nitric acid, organic sulfonic acid, etc., and the appropriate amount thereof to be used is about 50 to 200 mol % based on the aldehyde. In addition, formaldehyde, polyoxymethylene, hexamethylenetetramine, etc. are used as aldehyde, but acetaldehyde, butyraldehyde, butyraldehyde, butyraldehyde,
Glyoxal and the like can also be used. The appropriate amount of aldehyde to be used is about 20 to 140 parts per 100 parts of the polyvinyl alcohol polymer. The open-celled foam subjected to the acetalization reaction treatment may be made into a product (i.e., a hydrophilized cross-linked polyolefin open-celled foam) by simply washing with water, but the open-celled foam subjected to the acetalization reaction treatment or its washed product may be further processed. By contact treatment with an alkaline aqueous solution, there is a tendency for the texture, water absorption performance, etc. to be significantly improved. As the alkali, caustic soda, caustic potash, soda carbonate, calcium hydroxide, etc. are used, and the pH of the alkaline aqueous solution
is usually 9 or more, preferably 10 or more.
After this alkali treatment, the product is washed with water and dehydrated and dried. The resulting hydrophilized crosslinked polyolefin open-cell foam is sliced or cut into sheets, plates, blocks, or shapes having a desired thickness and length, and then used as a hydrophilic material.

【Example】

Next, the hydrophilic crosslinked polyolefin open cell of the present invention and its production method will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. Example 1 First, a 10% aqueous solution of modified polyvinyl alcohol (modified polyvinyl alcohol: Nippon Gosei Chemical Industry Co., Ltd.
Co., Ltd., product name: Gosenal T-350) 50 copies,
An acetalization solution was prepared by adding 12 parts of a 35% formalin aqueous solution, 15 parts of a 20% sulfuric acid aqueous solution, and 500 parts of water. In this acetalized liquid, cross-linked polyethylene open cell foam (product name: Opcel LC-300 #1, base material: ethylene-vinyl acetate copolymer, vinyl acetate content: approximately 15%, foaming ratio: approximately 32, Average bubble diameter:
Approximately 0.3mm, open cell rate: approximately 100%) (100x150x40mm)
The process of pressing and relaxing the open cells is repeated 10 times per minute to acetalize the open cells. The liquid was uniformly impregnated into the open cells. Next, the open cell impregnated with this acetalization liquid was placed in a polyethylene bag and left standing in a high-temperature dryer at a temperature of 50°C for 15 hours to carry out an acetalization reaction. The open-celled foam subjected to the acetalization reaction was taken out from the polyethylene bag, thoroughly washed with water until it became neutral, and then dried to obtain a hydrophilized cross-linked polyethylene-based open-celled foam. The resulting hydrophilized cross-linked polyethylene open cell foam is slightly harder when dry than the open cell foam used, but when wet or hydrated it has an elastic texture similar to that of human skin and is soft to the touch. Moreover, it had excellent hydrophilicity, water absorption and water retention properties. Example 2 The hydrophilized crosslinked polyethylene open cell obtained in Example 1 was immersed in an approximately 2% aqueous solution of caustic soda, squeezed and absorbed several times, and then thoroughly washed in water and dried to make it hydrophilic. A cross-linked polyethylene open cell body was obtained. The resulting hydrophilic crosslinked polyethylene open cell foam is softer when dry than before alkali treatment, and feels good to the touch when wet or hydrated.
Furthermore, the hydrophilicity, water absorption and water retention properties were further improved. Example 3 An acetalization solution was prepared in the same manner as in Example 1, except that a 10% aqueous solution of modified polyvinyl alcohol (modified polyvinyl alcohol: manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., trade name: Gosenal T-330) was used. , and a hydrophilized cross-linked polyethylene open-cell foam was obtained. The resulting hydrophilized cross-linked polyethylene open-cell foam is slightly hard when dry, but when wet or hydrated it has an elastic texture similar to that of human skin, and has good texture and excellent texture. It had hydrophilicity, water absorption and water retention properties. Example 4 The hydrophilic cross-linked polyethylene open cell obtained in Example 3 was subjected to alkali contact treatment in the same manner as in Example 2 to obtain a hydrophilic cross-linked polyethylene open cell. The resulting hydrophilized open-cell foam is softer when dry than before the alkali contact treatment, has particularly good texture when wet or contains water, and has extremely excellent hydrophilicity, water absorption, and water retention. It was hot. Example 5 200 parts of a 10% aqueous solution of modified polyvinyl alcohol (modified polyvinyl alcohol: Gosenal T-330 (mentioned above)), 60 parts of a 35% aqueous formalin solution, 40 parts of a 40% aqueous sulfuric acid solution, and 300 parts of water were uniformly mixed using a stirrer. By mixing, approximately 800 parts of acetalization liquid was prepared. Next, this acetalized liquid is made into an open cell structure (Opcel LC-300 #1 (mentioned above)) under reduced pressure in a closed system.
(250x170x10mm) impregnated sheet, temperature 50℃
The mixture was left standing for 24 hours to carry out the acetalization reaction. This open-celled cell subjected to the acetalization reaction treatment was thoroughly washed and dried to obtain a hydrophilized cross-linked polyethylene-based open-celled cell. The resulting hydrophilized cross-linked polyethylene open-cell foam is slightly hard when dry, but when wet or hydrated it has an elastic texture similar to that of human skin, and has good texture and excellent texture. It had hydrophilicity, water absorption and water retention properties. Example 6 The hydrophilic cross-linked polyethylene open cell obtained in Example 5 was subjected to alkali contact treatment in the same manner as in Example 2 to obtain a hydrophilic cross-linked polyethylene open cell. The resulting hydrophilized cross-linked polyethylene open-cell foam is softer when dry than before the alkaline contact treatment, and is particularly soft to the touch when wet or hydrated, and has excellent hydrophilicity, water absorption, and water retention. It was warm. Example 7 A hydrophilized crosslinked polyethylene open cell was obtained in the same manner as in Example 5, except that Gosenal T-350 (described above) was used as the modified polyvinyl alcohol. The resulting hydrophilized cross-linked polyethylene open-cell foam is slightly hard when dry, but when wet or hydrated it has an elastic texture similar to that of human skin, and has good texture and excellent texture. It had hydrophilicity, water absorption and water retention properties. Example 8 The hydrophilized crosslinked polyethylene open cell obtained in Example 7 was subjected to alkali contact treatment in the same manner as in Example 2 to obtain a hydrophilized crosslinked polyethylene open cell. The resulting hydrophilized cross-linked polyethylene open-cell foam is softer when dry than when subjected to alkaline contact treatment, and is especially soft to the touch when wet or hydrated, and has excellent hydrophilicity, water absorption, and water retention. It was warm. Example 9 Opcel as a crosslinked polyethylene open cell
LC-300 #2 (manufactured by Sanwa Kako Co., Ltd., base material: vinyl acetate copolymer, vinyl acetate content 15%, foaming ratio: approximately 35, average cell diameter: approximately 0.5 mm, open cell ratio:
A hydrophilized crosslinked polyethylene open cell foam was obtained in the same manner as in Example 5, except that 100%) was used. The resulting hydrophilized crosslinked polyethylene open-cell foam had good feel to the touch when wet or hydrated, and had excellent hydrophilicity, water absorption, and water retention. Example 10 The hydrophilized crosslinked polyethylene open cell obtained in Example 9 was subjected to alkali contact treatment in the same manner as in Example 2 to obtain a hydrophilized crosslinked polyethylene open cell. Example 11 Opcel as a cross-linked polyethylene open cell
LC-300 #3 (manufactured by Sanwa Kako Co., Ltd., base material: ethylene-vinyl acetate copolymer, vinyl acetate content:
Approx. 25%, foaming ratio: approx. 33, average cell diameter: approx. 0.3mm,
Example 5 except that open cell ratio: approximately 100%) was used.
A hydrophilized crosslinked polyethylene open-cell foam was obtained in the same manner as above. The resulting hydrophilized crosslinked polyethylene open-cell foam had particularly good feel to the touch when wet or hydrated, and had excellent hydrophilicity, water absorption, and water retention. Example 12 Polyvinyl alcohol: Gohsenol T-330
(Previous) 50 parts, 35% formalin aqueous solution 15 parts, 30%
An acetalization solution was prepared by uniformly mixing 20 parts of an aqueous sulfuric acid solution and 700 parts of water using a stirrer. Next, a hydrophilized crosslinked polyethylene open cell was obtained in the same manner as in Example 5, except that this acetalization liquid was used. The resulting hydrophilized crosslinked polyethylene open-cell foam had good feel to the touch when wet or hydrated, and also had excellent hydrophilicity and water absorption. Example 13 100 parts of a 10% aqueous solution of modified polyvinyl alcohol (modified polyvinyl alcohol: Gosenal T-330 (mentioned above)), 30 parts of a 35% aqueous formalin solution, 40 parts of a 30% aqueous sulfuric acid solution and 630 parts of water were uniformly mixed using a stirrer. The mixture was mixed to prepare an acetalization solution. Next, a hydrophilized crosslinked polyethylene open cell was obtained in the same manner as in Example 5, except that this acetalization liquid was used. The resulting hydrophilized crosslinked polyethylene open-cell foam had good feel to the touch when wet or hydrated, and had excellent hydrophilicity, water absorption, and water retention. Example 14 300 parts of a 10% aqueous solution of modified polyvinyl alcohol (modified polyvinyl alcohol: Gosenal T-330 (mentioned above)), 90 parts of a 35% aqueous formalin solution, 40 parts of a 30% aqueous sulfuric acid solution, and 370 parts of water were uniformly mixed using a stirrer. The mixture was mixed to prepare an acetalization solution. Next, a hydrophilized crosslinked polyethylene open cell was obtained in the same manner as in Example 5, except that this acetalization liquid was used. The resulting hydrophilized crosslinked polyethylene open-cell foam had good feel to the touch when wet or hydrated, and had excellent hydrophilicity, water absorption, and water retention.

【Effect of the invention】

As described above, the hydrophilized cross-linked polyolefin open-cell foam according to the present invention has excellent hydrophilicity and water absorption properties, as well as an elastic texture similar to that of human skin when wet or hydrated, and has good texture, as well as weather resistance. It has chemical resistance and mechanical strength, and is suitable for household, industrial,
It is suitably used as a water-absorbing or water-retaining material for interior decoration, personal items, agriculture, fisheries, and horticulture, and is extremely useful industrially.

Claims (1)

[Scope of Claims] 1. A hydrophilic crosslinked polyolefin open cell, characterized in that an acetalized product of modified polyvinyl alcohol is attached and included on the surface and within the open cells of the crosslinked polyolefin open cell. 2. The open cell material according to claim 1, wherein the modified polyvinyl alcohol is a polyvinyl alcohol having a high water absorption capacity and modified with an unsaturated carboxylic acid or a derivative thereof. 3. A cross-linked polyolefin open cell is impregnated with an aqueous solution of modified polyvinyl alcohol to which an acid and an aldehyde have been added, and then an acetalization reaction of the modified polyvinyl alcohol is carried out to form an acetalized product of the modified polyvinyl alcohol on the surface of the foam and within the open cells. 1. A method for producing a hydrophilic crosslinked polyolefin open-cell foam, characterized by adhering to and incorporating. 4. A cross-linked polyolefin open cell is impregnated with an aqueous solution of modified polyvinyl alcohol to which an acid and an aldehyde have been added, and then an acetalization reaction of the modified polyvinyl alcohol is carried out to form an acetalized product of the modified polyvinyl alcohol on the surface of the foam and within the open cells. adhering to and containing,
A method for producing a hydrophilized cross-linked polyolefin open-cell foam, which further comprises contact-treating the foam after the acetalization reaction with an alkaline aqueous solution.