JP2927466B2 - Water absorbent molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention absorbs most of water after removing the approximate water content with, for example, towels of hair wet with hair washing,
The present invention relates to a molded article having a plurality of comb-like teeth or brush pins that are excellent in water absorption and do not change in shape or strength when absorbing water.

[Conventional technology]

Conventionally, hair dryers have been mainly used for drying hair after shampooing.In recent years, however, the use of hair dryers has tended to be minimized as hair damage caused by hair dryers has been removed. It is in. Therefore, recently, a water-absorbing towel capable of absorbing most of the moisture of hair has been proposed. However, the water-absorbing towel alone does not provide sufficient contact with each individual hair, making it difficult to completely remove water, and only reduces the use of hair dryers. In order to remove moisture from the hair, it is necessary to improve the contact between the moisture and the absorbing material such as a towel, and at the same time, the water-absorbing material must quickly take the contacted water into the interior. In order to improve the contact with the hair, it is better to form it in the shape of a comb or a brush rather than a flat thing such as a towel.

U.S. Pat.No. 4,421,129 proposes a comb or brush molded from a composition containing a starch-based superabsorbent resin, but has a small water absorption rate when contacted with water.
There are problems such as swelling due to water absorption or occurrence of surface spatter. Japanese Utility Model Application Laid-Open No. 62-69910 discloses a paper comb.However, paper combs have problems such as insufficient rigidity and lack of strength at the time of water absorption. Was.

[Problems to be solved by the invention]

An object of the present invention is to solve the above-mentioned problems, and to provide a molded article which is excellent in water absorption and serves as a comb or a brush having no change in shape and strength when absorbing water.

[Means for solving the problem]

The present invention provides a tooth-shaped comb or a pin-shaped brush made of a hydrophilic porous sintered body having a porosity of 10 to 80% by volume obtained by subjecting a thermoplastic resin powder having a porosity of 10 to 80% by volume to a hydrophilic treatment of 5-2000 μm. The present invention relates to a molded article having a plurality of objects.

In the present invention, hair is a typical example of an object from which water is removed, and a comb or brush is a typical example of a molded body having a tooth-like or pin-like material of a hydrophilic porous sintered body. .

However, the invention is not limited to these. The object of water removal may be hair, fibrous, thread-like, shino-like or processed products thereof of humans, animals, plants, artificials and the like, and the shape of the molded article of the present invention may be any of these. Any shape and size may be used as long as it is a molded body having a plurality of teeth or pins arranged in parallel, non-parallel, radial, or the like, which can be combed. It is not limited to the shape of a comb or a brush.

In the present invention, the hydrophilic porous body is obtained by subjecting a thermoplastic resin powder to a hydrophilic treatment by a known method, and sintering the resultant into a porous body.

Examples of the thermoplastic resin include polyolefins such as polyethylene, polypropylene, ethylene / butene-1 copolymer, ethylene / 4-methylpentene-1 copolymer, ethylene / vinyl acetate copolymer, polystyrene, acrylonitrile / styrene copolymer Acrylonitrile-butadiene-styrene copolymer, polycarbonate, polymethyl methacrylate, polyamide, polyester, polyphenylene oxide, polyacrylonitrile, polyvinyl chloride, polyvinylidene chloride and the like. Above all, it is excellent in chemical resistance, does not cause dimensional change due to water absorption, does not cause strength reduction due to water absorption, can be stably obtained in large quantities at low cost, has sufficient strength as a sintered molded article, etc. Polyolefin resins are preferably used.

As the powder, it is also possible to use the powder obtained by polymerization as it is, or once formed into a shape other than powder, mechanically pulverized, frozen, or pulverized by a known method such as chemical pulverization. It is also possible to use. The average particle size of the powder is preferably in the range of 5 to 2000 μm, more preferably 50 to 1000 μm. If the average particle size of the powder is less than 5 μm, the whole becomes too dense when a sintered body is formed, and even if water is absorbed, the water absorption becomes extremely small. If the average particle size of the powder exceeds 2000 μm, it becomes difficult to form the details of the teeth of a comb or the pins of a brush, and water absorption due to the capillary phenomenon cannot be expected. The average particle size referred to in the present invention is obtained by using a comb of JIS Z8801 to obtain a cumulative distribution curve by the method specified by the residue test method JIS K0069. Is defined.

Various known methods for hydrophilizing these powders include a sulfonation method, a method of blending a specific surfactant, a method of grafting a hydrophilic monomer on the surface, and a method of providing a hydrophilic layer on the surface. And the method of hydrophilization. Among them, a sulfonated polyolefin disclosed in JP-A-57-167330, a polyolefin hydrophilized with a specific nonionic surfactant described in JP-A-63-061981, and the like can be preferably used. . It is also possible that after the hydrophobic powder is sintered and formed, it is hydrophilized by the above-mentioned known method.

The hydrophilic powder thus obtained is filled in a mold having a space in the shape of, for example, a comb or a brush, and is sintered and molded. Alternatively, it is also possible to punch or cut from a continuously sintered plate to form, for example, a comb or a brush. Furthermore, for example, it is possible to form a portion in contact with hair with a sintered compact, and combine it with a handle or handle formed of metal or plastic.

The porosity of the sintered compact is preferably 10 to 80% by volume. If the porosity is less than 10%, even if it absorbs water, it immediately saturates and is not practical. The porosity is 80%
If it exceeds, the water absorption capacity is excellent, but the strength as a sintered body is low.

 In the present invention, the porosity is defined as follows.

Where ρ ₀ = true specific gravity of raw material powder ρ ₁ = apparent specific gravity of porous sintered body W = weight of porous sintered body (g) V = volume of porous sintered body (cm ³ ) is there.

Although the size of the comb or brush in the present invention is not particularly limited, the thickness or diameter of a portion that comes into contact with water and has a water absorbing function (that is, a contact tooth or a brush pin portion) is 0.5. It is preferably not less than mm and not more than 10 mm. If the thickness or the diameter is less than 0.5 mm, it breaks or bends when contacting hair or the like, which is not practical. If the thickness or diameter exceeds 10 mm, heat is not uniformly distributed, and a good sintered molded product cannot be obtained. That is, when sintering is performed to the center, the outside is over-sintered and the pores are crushed, so that the water absorption speed is reduced or water is not absorbed. Conversely, if an attempt is made to maintain the outside with an appropriate porosity, the central portion becomes unsintered, and practical strength is not obtained.

Further, if necessary, addition of a heat stabilizer, an ultraviolet absorber, a fungicide, a fragrance, a hair styling agent, a hair tonic, etc. can be made without any problem as long as the hydrophilicity is not impaired.

[Examples] Next, the present invention will be specifically described with reference to examples.

Example 1 A melt index measured by ASTMD1238 (condition; load: 2.16 kg, temperature: 190 ° C.) is 0.1 g / 10 min, and density is 0.96.
High-density polyethylene powder (trade name: Sunfine SH-800, manufactured by Asahi Kasei Kogyo Co., Ltd.) having a particle size of 0 g / cm ³ and an average particle size of 105 μm is treated with fuming sulfuric acid (free SO ₃ 20%) for 3 minutes, and the exchange equivalent is 0.02. A milliequivalent / gram of sulfonated polyethylene powder was obtained. Exchange equivalent was sulfonated, the resin powder of the sulfonic acid (-SO ₃ H) form a W (g) collecting, 1N-was immersed in a calcium chloride aqueous solution as a equilibrium, hydrogen chloride generated during the aqueous solution Is titrated with a 0.1N aqueous solution of sodium hydroxide (titer; f). The equivalent point (titration; x (cc)) with the indicator phenolphthalein is determined and calculated by the following equation.

The obtained sulfonated polyethylene powder was treated with an aqueous sodium hydroxide solution to obtain a sodium sulfonate-type hydrophilic polyethylene powder. Filling the powder into an aluminum mold, heating until the mold surface temperature is 155 ° C.,
A comb-shaped sintered compact shown in FIG. 1 was obtained. The obtained molded body had a porosity of 40%. Approximately add water to the molded body with a dropper.
When 0.5 cc was dropped, the entire amount was absorbed into the molded body in about 10 seconds. The whole was immersed in water for one hour and taken out, and the dimensions and tensile strength were measured in a wet state. Table 1 shows the results.

Example 2 0.3 parts by weight of polyoxyethylene sorbitan monolaurate was added to 100 parts by weight of the high-density polyethylene powder used in Example 1 by a high-speed mixer (Henschel mixer manufactured by Mitsui Miike).
The mixture was dry-mixed while being heated to 85 ° C to obtain a hydrophilic powder.
The powder was filled in an aluminum mold and heated until the surface temperature of the mold reached 155 ° C. to obtain a comb-shaped sintered compact. FIG. 1 is a front view, and FIG. 2 is a side view of the tooth portion. A in FIG. 2 shows a dimension measurement position. The obtained molded body had a porosity of 40%. When about 0.5 cc of water was dropped on the molded body with a dropper, the entire amount was absorbed into the molded body in about 10 seconds. The whole was immersed in water for one hour and taken out, and the dimensions and tensile strength were measured in a wet state. Table 1 shows the results.

Comparative Example 1 The polyethylene powder used in Example 1 was directly used and filled in the same mold as in Example 1, and the surface temperature of the mold was reduced.
It was heated to 155 ° C. to obtain a comb-shaped sintered compact shown in FIG. The obtained molded body had a porosity of 40%. When about 0.5 cc of water was dropped on the molded body with a dropper,
Even after an hour, water droplets remained.

Comparative Example 2 Commercially available water-absorbing comb [trade name: Absorb A.
Comb (ABSORB-A-COMB), made in USA, USP 4,421,12
9, Japan sole agency; Sera International Co., Ltd.]
When about 0.5 cc of water was dropped with a dropper, water remained on the surface even after 5 minutes. The wet part was sticky.

Example 3 75 parts by weight of the high-density polyethylene powder used in Example 1, an ultra-high-molecular-weight polyethylene powder having a viscosity-average molecular weight of about 3.3 million, a density of 0.942 g / cm ³ , and an average particle size of 100 μm (trade name; Fine UH-900, manufactured by Asahi Chemical Industry Co., Ltd.) 25
0.3 parts by weight of polyoxyethylene sorbitan monolaurate were mixed with the same amount as in Example 1 to obtain a hydrophilic powder. The powder was charged into an aluminum mold and heated until the surface temperature of the mold reached 160 ° C. to obtain a brush-shaped sintered compact. FIG. 3 is a plan view, FIG. 4 is a side view thereof, and FIG. 5 is a side view of a pin portion of the brush. A indicates a measurement position of the dimension. Its porosity was 55%. When about 0.5 cc of water was dropped on the surface of this product with a dropper, it was absorbed into the molded body in about 10 seconds. The whole was immersed in water for one hour and taken out, and the dimensions and tensile strength were measured in a wet state. Table 1 shows the results.

〔The invention's effect〕

In the comb or brush made of the hydrophilic porous sintered body of the present invention, the material itself does not absorb water, and water is taken into pores between particles. No decrease in strength.

[Brief description of the drawings]

FIG. 1 is a front view of a comb-shaped sintered compact obtained in Examples 1 and 2, and FIG. 2 is a side view of a comb tooth portion. FIG. 3 is a plan view of the brush-type sintered compact obtained in Example 3, FIG. 4 is a side view, and FIG. 5 is a side view of a brush pin portion. The symbol A in FIGS. 2 and 5 indicates a dimension measurement position.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁶ , DB name) A45D 24/00-24/46 A46D 1/00 A46B 15/00

Claims (1)

(57) [Claims] 1. A comb tooth or brush made of a hydrophilic porous sintered body having a porosity of 10 to 80% by volume obtained by subjecting a thermoplastic resin powder of 5 to 2000 μm to a hydrophilic treatment and sintering and molding. A molded article having a plurality of pin-shaped objects.