JPS6343422B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a block-like hydrated polymer molded article (hereinafter simply referred to as "hydrated polymer molded article") having novel properties.

Conventionally, as a hydrous polymer molded product, a substance called hydrogel has been used for various purposes, such as heat insulating materials, cold insulating materials, fire prevention materials, and as a base for adhesive patches. Therefore, various manufacturing methods have been proposed to produce materials suitable for various required properties.

However, the following (1) -
No material has been found that has both the properties (3).

(1) The molded product does not deform even when kept in hot water.

(2) The adhesive strength of the molded product does not change depending on temperature.

(3) The molded product retains flexibility even at temperatures below the freezing temperature of water.

The present inventors have conducted various studies in order to obtain a hydrous polymer molded article having both of the above properties, and have succeeded in producing a hydrous polymer molded article that has both of the above properties according to the present invention. That is, the present invention provides a method for producing a hydrous polymer molded article having novel properties not seen in the prior art.

The invention will be explained in detail below.

The method for producing a hydrous polymer molded article of the present invention involves adding 100 parts by weight of natural rubber latex and/or a polymer latex having carboxyl groups (hereinafter simply referred to as "latex") produced by an emulsion polymerization method. Add 10 to 200 parts by weight of an oily substance;
It is characterized by adding 0.5 to 30 parts by weight of a polyether compound to the obtained mixture and molding it. The polymer latex is usually produced by emulsion polymerization.

Specific examples of polymers having carboxyl groups include butadiene, isoprene, styrene, acrylonitrile, methyl acrylate, acrylic acid-n
- At least one monomer selected from butyl, methyl methacrylate, ethylene, isobutylene, vinyl chloride, vinyl acetate, etc. and a monomer having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, or anhydride. Examples include copolymers with maleic acid, and polymers into which carboxyl groups are introduced by hydrolysis of ester groups, nitrile groups, acid anhydride groups, etc. A preferred polymer is a polymer obtained by copolymerizing 50% by weight or more of styrene and/or (meth)acrylic acid ester and butadiene with 0.5 to 20% by weight of an unsaturated carboxylic acid.

When producing a polymer latex by emulsion polymerization, it is preferable to use a surfactant having an anionic group. In this case, the surfactant having an anionic group includes anionic surfactants generally used in emulsion polymerization, such as alkyl-aryl sulfonates, alkyl sulfates, alkyl sulfonates, fatty acid soaps, rosin acid soaps, etc. etc. are given as preferable examples.

In addition, substances with anionic groups that have an emulsifying effect, such as water-soluble low-molecular-weight polymers containing carboxyl groups, may be produced during latex production. Water-soluble polymers having anionic groups may be included and such latexes may also be used to advantage.

The type of latex to be used is arbitrarily selected depending on the properties required depending on the use of the hydropolymer molded product, such as strength, elastic modulus, adhesiveness, etc. If necessary, the selected latex may be used alone, Alternatively, two or more types can be used in combination.

The concentration of natural rubber or polymer in latex is usually 20-50% by weight, but by concentrating it
It may be increased to about 70% by weight, or water may be added to increase the water content of the hydrous polymer molded product.

It is preferable that the latex be used after being thickened or creamed during processing. For thickening or creaming, common salt, ammonium chloride, sodium silicofluoride, caustic soda, cationic surfactants, sodium alginate, sodium polyacrylate, methylcellulose, carboxymethylcellulose sodium salt, etc. are added.

Oily substances to be added include soybean oil, coconut oil,
Valuable oils such as peanut oil, rapeseed oil, rice oil, sesame oil, cottonseed oil, linseed oil, and castor oil; vegetable essential oils such as turpentine oil and orange oil; mineral oils such as liquid paraffin, petrolatum, naphthenic oils, and aromatic oils; Examples include diethyl phthalate, di-n-butyl phthalate, di-2-ethylhexyl adipate, alcohol esters of higher fatty acids, and high-boiling esters such as tricresyl phosphate. Suitable oily substances vary depending on the type of latex, but in the case of styrene-butadiene-acrylic acid copolymer latex, soybean oil, castor oil, liquid paraffin with 30 to 40% naphthenic carbon, and phthalate esters. etc. are preferable.

When adding oily substances to latex and mixing,
Surfactants, fillers, anti-aging agents, etc. are added as necessary. The surfactant in this case may be either anionic or nonionic, and the HLB is not particularly defined, but nonionic surfactants with an HLB of about 3 to 9.5 are suitable. Such surfactants include higher fatty acid esters of glycerin and sorbitol, terminally esterified or etherified products of polyethylene glycol, and block copolymers of ethylene oxide and propylene oxide. In addition, as the filler, inorganic or organic powder substances that do not cause latotex to aggregate are used, such as carrion, bentonite, talc, calcium carbonate, silica, wheat flour, and tomorocidene powder.

The mixture obtained by adding an oily substance to the latex is sufficiently mixed to form a homogeneous cream or sticky substance.

Next, a polyether compound is added to this.
As the polyether compound, polyoxypropylene, oxyethylene-oxypropylene copolymer, polyoxytetramethylene, etc. are used. These have 1 to 6 hydroxyl groups at the end of the molecule. Preferred polyethers have a molecular weight of 1000~
6000 polyoxypropylene. Latex is unstable with respect to polyether, and when a polyether compound is added to a mixture of latex and oily substance, it gradually loses fluidity and becomes a water-containing lump. Particularly in the case of polymer latex, if the pH is below 7, it tends to form lumps. The preferred polymer latex has a PH range of 3-7.

The time required for agglomeration varies depending on the material used, but it is formed into the desired shape before fluidity is lost, depending on the intended use of the final product.
For example, before it loses its fluidity, it is packed into a bag of the desired shape or spread on another material (in the case of a patch base, it is applied to a base fabric), etc. .

The agglomeration time can be adjusted by selecting the type of polyether compound and adjusting the amount added. The smaller the molecular weight of the polyether compound, the
Moreover, the larger the amount added, the shorter the agglomeration time.

A polyvalent metal compound may be added at the same time as the polyether compound. The polyvalent metal compound is not particularly limited, and halides and sulfates of calcium, magnesium, aluminum, zinc, etc., which are generally used for coagulating latex, are preferably used. Hydroxides and oxides of these metals are also used. Preferred polyvalent metal compounds include calcium sulfate, calcium chloride, magnesium sulfate, aluminum chloride, aluminum sulfate, calcium hydroxide, calcium oxide, and zinc oxide. Addition of a polyvalent metal compound makes it easier to control the agglomeration time and physical properties of the agglomerates.

The ratio of the latex and other additives used is 10 to 200 parts by weight of the oily substance and 0.5 to 30 parts by weight of the polyether per 100 parts by weight of the latex. When the amount of oily substance exceeds 200 parts by weight, the obtained hydropolymer molded product becomes too flexible and its shape retention becomes poor.
Oily substances begin to ooze out from the obtained hydropolymer molded product. In addition, if it is less than 10 parts by weight, water tends to separate from the molded product. It is acceptable to add more than 30 parts by weight of polyether, but it loses fluidity in a short period of time, making molding difficult.
A particularly preferred ratio of latex and other additives is 20 to 20 parts by weight of oily substances per 100 parts by weight of latex.
150 parts by weight, and 1 to 20 parts by weight of polyether.
When adding a polyvalent metal compound, add 0.1 to 5
Preferably, parts by weight are added.

Of course, other additives may be added during the process of the method of the invention, such as fillers, drugs, fragrances, etc.

The hydrous polymer molded product obtained by the present invention has the following characteristics not found in conventional similar products.

(1) No deformation even when kept in hot water.

(2) Adhesive strength does not change with temperature.

(3) Elasticity does not change much with temperature.

(4) Remains flexible even below the freezing temperature of water.

(5) There is no separation of water in the repeated history of high and low temperatures.

(6) Can be easily processed and molded at room temperature.

(7) Volatile additives such as drugs, fragrances, etc. can be added during the molding process to prevent their escape.

The above characteristics indicate that the water-containing polymer molded product obtained by the present invention has extremely excellent properties as a cold pack. When used as a base material, it has the following advantages.

(1) Since it is manufactured at room temperature, there is no volatilization of medicinal ingredients due to heat.

(2) Since the base material itself has appropriate adhesiveness, there is no need to use any other adhesive.

(3) The adhesiveness of the base material itself is moderate, so it does not damage the skin when peeled off.

(4) Since water evaporates continuously, it has an excellent cooling effect and provides a long-lasting anti-inflammatory effect.

(5) It is flexible and has good followability to changes in the form of deposits. (Follows the bending and stretching of the skin well) (6) Little change in elasticity due to temperature.

(7) Water does not separate as droplets.

(8) No stickiness during high temperatures (summer or when the affected area has a fever).

Examples are listed below.

Example 1 Natural rubber latex (natural rubber content: 60% by weight) 100 parts by weight 10% sodium alginate aqueous solution 10 parts by weight soybean oil 50% Liquid paraffin 10% are mixed. This mixture and 5 parts by weight of polyoxypropylene (molecular weight 4000) were continuously mixed and extruded at room temperature using an extruder, and the mixture was filled into a polyethylene bag. It became a lump in about 10 minutes and became a bag-shaped water-containing polymer. The water-containing polymer sealed in this polyethylene bag remains flexible even at -20°C, remains unchanged in appearance and hardness even after being kept at 50°C for 1 week, and is maintained at 45°C for 12 hours and at -15°C for 12 hours. No change was observed even after the heat cycle was repeated 10 times, making it suitable as a cold insulator.

Example 2 PH emulsion polymerized using anionic surfactant
7 Styrene-methyl methacrylate-butadiene-acrylic acid copolymer latex (acrylic acid copolymerization amount: 3% by weight, solid content: 50%) 100 parts by weight Soybean oil 30〃 Sodium polyacrylate 1〃 Mixed for 30 minutes at room temperature Then, it was made into a soft rice cake shape.
In addition, polyoxypropylene (molecular weight 1000),
10 parts by weight of oxyethylene-oxypropylene copolymer (molecular weight 3000) or polyoxytetramethylene (molecular weight 2000) was added, mixed for 3 minutes at room temperature, and formed into a 2 mm thick sheet using a doctor blade. Each sheet became a hydrous polymer sheet with flexible rubber elasticity that did not lose its fluidity in about 30 minutes. This water-containing polymer sheet did not separate water as droplets, and even when immersed in water at 30°C for 48 hours, there was no change in volume or stickiness on the surface.

Example 3 Styrene-butadiene-acrylic acid copolymer latex with pH adjusted to 5 (acrylic acid copolymerization amount: 5% by weight, solid content: 50%) 100 parts by weight Kaolin 20 Sodium alginate 1 Soybean oil 30 Methyl salicylate 5 l-menthol 5 dl-camphor 5 were mixed at room temperature for 30 minutes to form a cream. To this, a mixture of 4 parts by weight of polyoxypropylene (molecular weight 4000) and 1 part by weight of calcium sulfate was added and mixed for 3 minutes at room temperature, and then the mixture was applied on flannel to a thickness of 1 mm. The mixture did not lose fluidity in about 1 hour and became a hydrous polymer sheet.

This water-containing polymer sheet adheres well to the skin and
This adhesive did not change with temperature or humidity, did not damage the skin when removed, and had an excellent poultice effect, making it suitable as a poultice.

Comparative Example 1 Natural rubber latex (natural rubber content: 60% by weight) 100 parts by weight 10% sodium alginate aqueous solution 10 parts by weight Soybean oil 50 parts by weight Liquid paraffin 10 parts by weight were mixed. Quickly mix this mixture with 10 parts by weight of a 25% by weight aqueous solution of sodium silicofluoride at room temperature,
It was filled into a polyethylene bag. It agglomerated in about 5 minutes and became a bag-shaped water-containing polymer. The water-containing polymer sealed in this polyethylene bag exudes water when pressurized, and the rubber content and water were completely separated by holding it at 50°C for one week.

Claims (1)

[Claims] 1 Add 10 to 200 parts by weight of an oily substance to 100 parts by weight of natural rubber latex and/or a polymer latex having carboxyl groups produced by emulsion polymerization method, and add a polyether compound to the resulting mixture.
1. A method for producing a block-like hydrous polymer molded article, which comprises adding 0.5 to 30 parts by weight and molding it.