JP2002105324A - High specific gravity molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high specific gravity molded article, such as a weight balancer, needing both weight touch and processability. SOLUTION: This high specific gravity molded article characterized by excluding and molding a synthetic resin composition comprising a synthetic resin and tungsten powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high specific gravity molded article such as a weight balancer.

[0002]

2. Description of the Related Art Synthetic resins are easy to process, have excellent corrosion resistance, are light in weight, are relatively inexpensive, and have good insulation properties as compared with metal materials. In recent years, electric and electronic parts, mechanical parts,
As materials and structural materials for precision parts and general industrial parts,
It is widely used in many fields.

[0003] Synthetic resins are more excellent in workability than metal materials that require cutting and sintering processes.

By the way, weight balancers for adjusting the balance used in bicycles and various machines, such as weight balancers mounted on wheels for adjusting the wheel balance of automobiles and the like, have hitherto been known.
Lead, which is a metal material having a high specific gravity and relatively good workability, has been used as a material for forming a weight balancer.

[0005] However, lead is toxic, and lead, which has entered the human body through the skin, is extremely difficult to excrete when deposited on bones, and accumulates in the human body. When lead accumulates in the body of everybody, there is no possibility that lead poisoning will occur. Therefore, it is desired that the weight balancer and the like described above be formed of a material other than lead. However, at present, there is no material having high specific gravity and moderate workability like lead.

An object of the present invention is to provide a high specific gravity molded article such as a weight balancer which requires both a feeling of weight and workability comparable to lead by using a synthetic resin.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a high specific gravity molded article obtained by extruding a synthetic resin composition containing a synthetic resin and tungsten powder. It is.

The synthetic resin used in the present invention is a thermosetting resin or a thermoplastic resin. In particular, the thermoplastic elastomer is preferably used in an amount of 30% by weight or more, and more preferably 50% by weight or more, from the viewpoint of productivity.

Specific examples of the thermosetting resin include phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin and the like.

Specific examples of the thermoplastic resin include polyamides such as nylon 6, nylon 66 and nylon 12, polyesters such as polybutylene terephthalate and polyethylene terephthalate, polyolefins such as polycarbonate, polypropylene and polyethylene, polystyrene, polyphenylene sulfide, and the like. ABS and liquid crystal polymer are exemplified.

A thermoplastic elastomer has both a rubber component (soft segment) having elasticity in a molecule and a molecular constraint component (hard segment) for preventing plastic deformation. Specifically, a styrene-based thermoplastic elastomer in which the hard segment is polystyrene, the soft segment is (hydrogenated) polybutadiene or (hydrogenated) polyisoprene, the hard segment is polyethylene or polypropylene, and the soft segment is ethylene.
Olefin thermoplastic elastomer such as propylene / diene copolymer (EPDM) or butyl rubber, polyester hard segment is polyester, thermoplastic polyester elastomer such as polyether or aliphatic polyester, hard segment is urethane structure, soft segment is soft segment Examples include urethane-based thermoplastic elastomers such as polyethers and polyesters, polyamides whose hard segments are polyamides, and polyamide-based thermoplastic elastomers whose soft segments are polyethers and polyesters.

Further, a 1,2-polybutadiene-based thermoplastic elastomer in which the hard segment is syndiotactic 1,2-polybutadiene, the soft segment is amorphous polybutadiene, and the hard segment is trans 1,4
-Polyisoprene, trans 1,4-polyisoprene thermoplastic elastomer whose soft segment is amorphous polyisoprene, metal carboxylate ion cluster whose hard segment is amorphous, ionomer whose soft segment is amorphous polyethylene, hard segment is crystalline polyethylene, PE / EEA, EVA thermoplastic elastomer whose soft segment is ethylene-ethyl acrylate copolymer or ethylene-vinyl acetate copolymer, fluorine thermoplastic elastomer whose hard segment is fluororesin, and soft segment is fluororubber Etc. can also be used.

Further, the thermoplastic elastomer used is:
Considering outdoor use, it is necessary to have excellent weather resistance, aging resistance and heat resistance. Specific examples of the thermoplastic elastomer that satisfies such requirements include polyester-based thermoplastic elastomers in which the hard segment is polyester and the soft segment is polyether or aliphatic polyester. More specifically, a polyester using a copolymerized polybutylene terephthalate unit obtained by copolymerizing polybutylene terephthalate or isophthalic acid for the hard segment, and an aliphatic polyether unit such as poly (tetramethylene oxide) glycol for the soft segment. Polyether type polyester thermoplastic elastomer or copolymerized polybutylene terephthalate unit in which hard segment is copolymerized with polybutylene terephthalate or isophthalic acid, and aliphatic polyester such as poly (ε-caprolactone) or polybutylene adipate in the soft segment And polyester-type thermoplastic elastomers of the polyester-polyester type.

In the case of a polyester-polyether type polyester thermoplastic elastomer, the physical properties greatly change depending on the content and molecular weight of poly (tetramethylene oxide) glycol. That is, the higher the content of poly (tetramethylene oxide) glycol, the softer, and the lower the molecular weight, the softer but the heat resistance decreases.
Polymerization is carried out by melt polycondensation similarly to polyethylene terephthalate and polybutylene terephthalate, and there are two types, a DMT method using dimethyl terephthalate and a direct polymerization method using terephthalic acid, depending on the raw materials.

In the case of a polyester-polyester type polyester thermoplastic elastomer, polymerization is performed by suppressing the randomization of the polyester component constituting the hard segment and the polyester component constituting the soft segment by a transesterification reaction with a phosphoric acid or phosphorus compound. . There are three specific manufacturing methods. The first method is
After melt-mixing a crystalline polyester having a high degree of polymerization such as polybutylene terephthalate constituting a hard segment and an aliphatic polyester such as poly (ε-caprolactone) constituting a soft segment, and performing blocking by transesterification, This is a method in which a phosphorus compound or the like is added before randomization to suppress randomization. The second method is to use a low-polymerization degree crystalline polyester such as polybutylene terephthalate having OH groups at both terminal groups constituting the hard segment and OH groups at both terminal groups constituting the soft segment.
In this method, an aliphatic polyester such as poly (ε-caprolactone) and an isocyanate compound are simultaneously melt-kneaded. In the third method, ε-caprolactone was added to and dissolved in a crystalline polyester having a high degree of polymerization such as polybutylene terephthalate constituting a hard segment, and ring-opening polymerization of ε-caprolactone was performed, and at the same time, block formation was performed by transesterification. After that, before randomization, a phosphorus compound or the like is added to suppress randomization.

Also, hydrogenated styrene-based thermoplastic elastomers (SEPS, SEBS) in which a polyisoprene portion or a polybutadiene portion constituting an intermediate soft segment is hydrogenated and saturated are also suitable. It is also possible to use a hydrogenated styrene-based thermoplastic elastomer containing a butadiene unit in the intermediate isoprene portion.
It may be a mixture of hydrogenated styrene thermoplastic elastomers.

For example, in the case of the above-mentioned SEPS, physical properties change depending on the styrene content, the molecular weight of isoprene, the molecular weight distribution, and the like. That is, the hardness increases as the styrene content increases, and the strength increases as the molecular weight of isoprene increases. Also, the moldability decreases as the molecular weight distribution becomes sharper. In particular, when the molecular weight of isoprene is large and the molecular weight distribution is sharp, molding becomes extremely difficult.

These styrenic thermoplastic elastomers are prepared by using a monofunctional initiator such as alkyl lithium.
A block copolymer is produced by living polymerization in the order of styrene-isoprene-styrene, styrene-butadiene-styrene (three-step polymerization using a monofunctional initiator) and hydrogenated, or by using a similar initiator. Similarly, it can be produced by a method of producing a block copolymer (two-step polymerization coupling method) by coupling with an alkyl dihalide after living polymerization, followed by hydrogenation. The thermoplastic elastomer used in the present invention may be in the form of pellets or powder.

Tungsten used in the present invention is desirably in a powder form because it must be uniformly blended with a synthetic resin. In the present invention, a high specific gravity molded product is obtained by extrusion molding. In this case, the particle diameter of the tungsten powder is preferably 300 μm or less in appearance, and from the viewpoint of productivity, 2 to 200 μm, particularly preferably 3 to 50 μm. It is. If the particle diameter of the tungsten powder is large, the synthetic resin composition is difficult to pass through the gate of the mold, and the moldability is reduced. Further, when the particle diameter is extremely small, the surface area of the tungsten powder increases, and it becomes impossible to completely cover the surface of the tungsten powder with a predetermined amount of synthetic resin.

The tungsten powder used in the present invention is preferably subjected to a coupling treatment in order to increase the affinity with the resin. As the coupling agent, titanate-based, aluminum-based, silane-based or the like is used, but in the present invention, silane-based has the highest affinity improving effect.

The amount of the synthetic resin used in the present invention is preferably 1% by weight or more. In particular, when a thermoplastic resin or a thermoplastic elastomer is used, the content is preferably 2% by weight or more. This is because if the compounding amount of the synthetic resin is less than 1% by weight, the mechanical strength is small and practical use is difficult.

The compounding amount of the tungsten powder used in the present invention is preferably 80% by weight or more. In this case, the specific gravity becomes 5 or more, which fulfills a sufficient function as a weight balancer.

When used as a weight balancer, a bicycle, various machines, or sports equipment mounted on a wheel of an automobile, the specific gravity is preferably 8 or more, more preferably 9 or more, and particularly preferably 10 or more. The amount of tungsten powder to ensure this specific gravity is
When the synthetic resin is nylon 6, the content is 91% by weight or more, 93% by weight or more, and 94% by weight or more, respectively. Further, when a specific gravity 11 equal to or higher than that of lead is required, the specific gravity 11 is 95.5% by weight or more.

Incidentally, the thermoplastic resin composition of the present invention includes:
As long as the object of the present invention is not impaired, in addition to rubber and low molecular weight components as necessary, ordinary additives, for example, antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, crystallization accelerators, Coupling agents, aggregates, additive impregnating liquids, pigments, dyes, softeners, antioxidants, crosslinking agents, and the like can be added.

The method for producing a high specific gravity molded article of the present invention employs an extrusion molding method. Specifically, it is a method using a single screw extruder or a twin screw extruder. A mixture of a thermoplastic elastomer and tungsten powder or a pellet obtained by melt-kneading using a single-screw or twin-screw extruder is supplied to a hopper of an extruder, and heated and melted by a screw in a heating tower. It is obtained by cooling through a die attached to the tip. As the shape of the die, there are a T-die used for extruding a plate-like shape, and a round die used for extruding a tube or pipe.

When the synthetic resin is a thermosetting resin, a ram extruder is used.

In the extrusion molding, since a molded product having a continuous cross-sectional shape can be manufactured, the obtained molded product can be cut into an arbitrary size and used. In particular, in order to prevent rollover of a weight balancer or a long object such as an automobile, a plate-like molded product obtained by extrusion molding is cut into an arbitrary size, and is cut through a double-sided adhesive tape or an adhesive. A method of bonding to an object to be bonded is given.

The double-sided pressure-sensitive adhesive tape to be mounted on the high specific gravity molded product of the present invention is not particularly limited, and a commercially available product can be used. Further, a double-sided pressure-sensitive adhesive tape or a pressure-sensitive adhesive covered with release paper may be applied to the surface so that the pressure-sensitive adhesive can be easily bonded to an object to be bonded.

The adhesive directly applied to the high specific gravity molded article of the present invention may be an adhesive or the like usually used for a double-sided adhesive tape. Specific examples include silicone-based and elastomer-based. When this method is used, it is desirable to apply the adhesive in advance and then cover the adhesive with a release paper. The adhesive may be removed and the release paper may be removed and bonded to the adherend.

As other bonding methods, there are a method of directly applying an adhesive and bonding to an object to be bonded, a fixing method using a screw, and the like, but are not limited thereto, and a known method may be used. I can do it.

As described above, the high specific gravity molded article of the present invention can be used as a substitute for a toxic lead balance weight, and can be used for various sports equipment, electric / electronic parts, mechanical parts, etc. It can be used for various applications.

Further, the high specific gravity molded article of the present invention has an advantage that, in particular, when a thermoplastic resin or a thermoplastic elastomer is used, the used material can be recycled by melting and molding to regenerate the used material. is there.

[0033]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these examples. Prior to the examples, a silane coupling treatment method for tungsten powder will be described.

(Silane Coupling Treatment Method) As a silane coupling agent, γ- (2-aminoethyl) aminopropyltrimethoxysilane (SH6020, manufactured by Dow Corning Toray Silicone Co., Ltd.) was used.
0.3 parts of silane coupling agent was added to the tungsten powder being stirred in the mixing tank (super mixer) with high-speed stirring blades.
% By weight, and stirring was continued until the temperature in the tank reached 120 ° C. Thereafter, the mixture was cooled and used as a silane-coupled tungsten powder.

Example 1 As a thermoplastic elastomer, 5% by weight of a powder of a polyester-based thermoplastic elastomer (Perprene P-90B, polyester / polyether type, manufactured by Toyobo Co., Ltd.) was averaged by a silane-based coupling treatment beforehand. After mixing 95% by weight of tungsten powder (produced by Tokyo Tungsten) having a particle diameter of 13 μm, premixing in a mixing tank with a high-speed stirring blade (super mixer), melt-kneading with a single-screw extruder having a screw diameter of 25 mm to form pellets. Obtained. The pellets are dried by heating under reduced pressure (100
° C) and a screw diameter of 30 mm with an extruder of 10 mm width,
A long extrusion product having a thickness of 6 mm was obtained. Specific gravity is 10.
It was 3. Cut every 20mm in length, 10mm x 20
A silicone-based pressure-sensitive adhesive was applied to the mm surface and covered with release paper.
The release paper was peeled off and 10 sheets were stuck on the bottom of the trophy.
As a result, the trophy became more stable against rollover.

Comparative Example 1 As the thermoplastic elastomer, only the polyester-based thermoplastic elastomer used in Example 1 was extruded to obtain a molded product having the same size as that of Example 1. This was affixed to the trophy in the same manner as in Example 1, but there was no change in the stability of the trophy against rollover.

Example 2 1.2% by weight of the polyester-based thermoplastic elastomer powder used in Example 1 as the thermoplastic elastomer, and 1.2% by weight of the polybutylene terephthalate powder as the thermoplastic resin. 97.6% by weight of the used tungsten powder was blended, pellets were obtained in the same manner as in Example 1, and a long extruded product having a width of 10 mm and a thickness of 6 mm was obtained using a single screw extruder. The specific gravity was 13. 10m after cutting to length 15mm
A double-sided adhesive tape (# 4213, manufactured by Sumitomo 3M Limited) was attached to the mx 15 mm surface and attached to an aluminum wheel of an automobile to use as a balancer, but there was no problem.

Example 3 3.0% by weight of a hydrogenated styrene-based thermoplastic elastomer (Septon 2063, manufactured by Kuraray Co., Ltd.) as a thermoplastic elastomer, tungsten having an average particle diameter of 27 μm previously subjected to a silane-based coupling treatment 97% by weight of a powder (manufactured by Tokyo Tungsten) was blended to obtain a molded product similar to that of Example 2, which was similarly used as a balancer, but there was no problem.

As described above, in the present invention,
There is no need to worry about lead poisoning because no lead is used. Since it is made of synthetic resin, it can be easily cut with a saw or the like. A molded article to which a double-sided adhesive tape has been previously attached or a molded article to which an adhesive has been applied can be easily bonded to an object.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16F 15/32 Z (72) Inventor Kazuo Haruta 4-1 Kanebocho, Hofu City, Yamaguchi Prefecture Kanebo Gosen Co., Ltd. F-term (reference) 4F071 AA47 AB06 AF06 AH07 AH08 BA01 BB06 BC03 4J002 AA001 AC081 BB031 BB121 BB151 BC031 BC051 BL001 BN151 BP011 BP031 CC031 CC161 CC181 CD001 CF061 CF071 CF211 CG001 CL011 FB0011

Claims (3)

[Claims] 1. A high specific gravity molded article obtained by extruding a synthetic resin composition containing a synthetic resin and tungsten powder. 2. The high specific gravity molded article according to claim 1, wherein the content of the synthetic resin is 1 to 20% by weight and the content of the tungsten powder is 80 to 99% by weight. 3. The high specific gravity molded article according to claim 1, wherein the synthetic resin is a thermoplastic elastomer.