JPH08308908A - Tooth hardening device - Google Patents

Abstract

PURPOSE: To obtain a tooth hardening device with excellent safety and a better touch of using by integral molding of a thermoplastic elastomer comprising a block copolymer of a polystyrene block and a specified polyolefin block and a polypropylene resin. CONSTITUTION: A thermoplastic elastomer 1 comprising a block copolymer of a polystyrene block and a polyolefin block comprising a polyethylene/ polypropylene copolymer and a polypropylene resin 2 are molded integrally to form a tooth hardening device, for example, given a shape of a bear. The content of styrene in the thermoplastic elastomer 1 is 30-40wt.% and the elastomer, as elastic as rubber at a normal temperature, is formed so as to be softened into a thermoplastic state when heated. With such a manner, the polystyrene block serves as cross-linking point while being thermoplastic below the glass transition temperature of the polystyrene.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to teeth. More specifically, the present invention relates to teeth formed by integrally molding resins having different hardness.

[0002]

2. Description of the Related Art Infants have an itchy gum at the beginning of their teeth, and they want to put anything in their mouth and chew. Therefore, in order to relieve the itchiness of the gums and promote the development of teeth, 3 to 1 days after birth
It is because the teeth are given to an 8-month-old baby.

[0003] In the conventional tooth pad, the bite portion has a constant hardness, and a plurality of portions having different hardness, that is,
Some are composed of a moderately hard portion and a softer portion (for example, Japanese Utility Model Laid-Open No. 1-98644). When comparing the two, the former tooth is only a practicing practice for bites with a certain hardness, and it is not possible to practice chewing from a soft object to a hard object, while the latter tooth is so difficult. There is no problem and it is more desirable.

At present, an extremely large number of types of both hard resins and soft resins are known, and one having a suitable hardness and a feeling of use is selected from these, and a plurality of types having different hardness described above are selected. It is conceivable to produce a toothed tooth consisting of parts. In a general plastic molded product, integration is achieved by a method of using an adhesive, a method of fitting the connecting portions of the both into a male and female concave and convex shape, and the like.

However, in the case of the integration method using an adhesive, since both members are different from each other, defective adhesion may occur. Further, an organic solvent is often used for the adhesive, which is not preferable from the viewpoint of safety. Further, in the method of fitting both members, the mold for molding each member is complicated and expensive, and the fitting work is very complicated.

On the other hand, as a method for integrally molding a plurality of resins without being limited to teeth, a polypropylene resin is melt-injection-molded in a mold, and then a non-vulcanized thermoplastic elastomer is melt-injected. Japanese Patent Publication No. 2-8572 discloses a method for producing a composite plastic molded product in which a polypropylene member and a thermoplastic elastomer member are integrally fusion-molded. Since the method disclosed in this publication does not use an adhesive or a fitting technique, it is excellent in safety, economy and simplicity. However, although the safety of the member itself is particularly important because it is used exclusively by babies for dental prosthesis, there is no description about the safety of the member itself or its application to dental prosthesis.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a tooth composed of members having different hardness, and the member uses an adhesive or male-female type fitting as described above. The object is to provide a tooth with a highly safe and comfortable feeling that can be integrally molded without using a tooth.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to solve the above-mentioned problems and found that a specific thermoplastic elastomer and a polypropylene resin were adhered to each other in a molten state at their joints. The inventors have found that the teeth formed by firmly and integrally fusing together are excellent in safety and have a good feeling of use such as chewyness and texture on the tongue, and have completed the present invention.

That is, the gist of the present invention is that (1) a thermoplastic elastomer, which is a block copolymer of a polystyrene block and a polyolefin block of a polyethylene / polypropylene copolymer, and a polypropylene resin are integrally molded. Due to the characteristic tooth, and (2) the tooth according to (1) above, wherein the styrene content in the thermoplastic elastomer is 30 to 40% by weight,
It is about.

The thermoplastic elastomer used for the tooth of the present invention is a material having elasticity similar to that of rubber at room temperature but softening by heating to exhibit plasticity. The polystyrene block and the polyethylene / polypropylene copolymer. And a block copolymer (hereinafter abbreviated as “SEPS”) made of a polyolefin block. Specifically, Septon 1001, 1050, 200
2, 2007, 2104, 2063, 2043, 202
3, 4033, 2005, 2006 and 4055 (all made by Kuraray).

[0011] SEPS has thermoplasticity because the polystyrene block functions as a cross-linking point below the glass transition temperature of polystyrene, while it does not undergo chemical cross-linking such as vulcanization. In addition, the polyolefin block plays a role of expressing the properties of rubber. Therefore, in addition to good processability, 1) shows high elasticity and high strength like vulcanized rubber without vulcanization, and 2) has good affinity with olefin-based polymers and styrene-based polymers, and 3) It is preferably used for the product of the present invention because it has the property of being excellent in safety. In the present invention, the rubber hardness and the like can be changed by changing the styrene content in SEPS, but the rubber hardness (JIS-A type) Hs of the elastomer used for tooth dents is generally 20 to. The range is 90 degrees. In the present invention, a thermoplastic elastomer having a styrene content of 30 to 40% by weight is particularly preferably used because it has appropriate rubber hardness and elasticity due to teeth.

The polypropylene resin used in the present invention is a polymer mainly composed of a propylene monomer and may contain a small amount of a copolymerizable olefin as a copolymerization component. Polypropylene resin is widely used as a raw material for various fibers and molded products. Any of these conventionally known polypropylene resins can be used in the present invention. Further, since such polypropylene resin is an unsaturated hydrocarbon, the elution property of the resin is low and it is chemically stable, so that the safety is high. Further, since the SEPS has a high affinity with the polyolefin block, the adhesive force by molding is also excellent.

By integrally molding these two types of members, the tooth of the present invention is manufactured. In the present specification, "integral molding" means that both members are integrally fused in a molten state at their joints without using an adhesive or a male-female fitting. . In the case of integrally molding two kinds of members, it is generally difficult to simply bond arbitrary resins by simply fusing because the physical properties such as fluidity and viscosity are different for each resin. However, it is considered that the reason why SEPS and polypropylene resin can be integrally molded in the present invention is that SEPS has the same fluidity and viscosity as polypropylene resin at the time of production. The integral molding can be carried out by an injection molding method in which a polypropylene resin is injection-molded, then a thermoplastic elastomer is injected, and both are fused at the same time as the molding. The molding conditions themselves may be the same as the conventional general molding conditions.

Since the pigment of any color can be mixed in the resin, the color for the teeth can be set arbitrarily.
Also, by changing the mold for injection molding, animals,
It can be shaped according to the preference of the baby, such as plants, fish and vehicles.

The teeth thus obtained are excellent in safety and have a good feeling in use such as chewyness and texture on the tongue.

[0016]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples.

Example 1 Using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.), 12 parts by weight of polypropylene resin (manufactured by Showa Denko KK) was used to prepare about 18 parts.
It was melted at 0 ° C. and poured into a mold. After the polypropylene resin was solidified, 10 parts by weight of SEPS (Septon 2006, manufactured by Kuraray) was melted at about 190 ° C. and poured into the same mold. After cooling the mold, the molded product was taken out to give a tooth flutter (FIGS. 1 and 2). Due to the resulting teeth, the polypropylene resin portion and the SEPS portion were both melt-bonded together and completely integrated at the boundary portion, and peeling could not be performed.

The hardness of the SEPS part for the resulting tooth,
The elasticity was measured. The hardness was measured according to the JIS K6301 hardness test, and the elasticity was measured according to the JIS K6301 compression set test.

As a result, the hardness was 65 degrees and the elasticity was about 40% compression set, so that the tooth of the present invention had a good feeling in use. Further, when the two members were integrated, no adhesive or the like was used, and the members themselves were not toxic, so that the tooth of the present invention was highly safe.

[0020]

EFFECTS OF THE INVENTION The tooth of the present invention is composed of members having different hardnesses, which is excellent in safety and has a good feeling in use.

[Brief description of drawings]

FIG. 1 is a plan view for a tooth-shaped tooth according to the invention shaped like a bear.

FIG. 2 is a plan view for a toothed tooth according to the invention shaped like a car.

[Explanation of symbols]

 1 Thermoplastic elastomer 2 Polypropylene resin

Claims (2)

[Claims] 1. A polystyrene block and polyethylene /
Tooth characterized by being integrally molded with a thermoplastic elastomer which is a block copolymer made of a polyolefin block made of a polypropylene copolymer and a polypropylene resin. 2. The tooth according to claim 1, wherein the styrene content in the thermoplastic elastomer is 30 to 40% by weight.