JPH0364364A - Structural material of timepiece - Google Patents

Abstract

PURPOSE:To obtain a structural material of timepieces having a beautiful surface skin and improved in the sales appeal, strengths, flow, etc., by melt- kneading a resin composition comprising a thermoplastic resin, a specified graphitized vapor growth carbon fiber and a metallic powder. CONSTITUTION:A vapor growth carbon fiber is heat-treated at 1500 deg.C, desirably 2100-3000 deg.C in an inert gas atmosphere to obtain an graphitized vapor growth carbon fiber having a fiber diameter of 0.01-4mum, a fiber length <=5000mum, a carbon purity >=98.5%, and a lattice constant (X-ray diffraction) in the crystal structure of graphite <=6.88 and containing 3-500mueq/g of acidic functional groups. A resin composition is obtained by mixing 20-70wt.% thermoplastic resin, desirably a nylon 66 resin of a mol.wt. of 15000-45000, with 5-50wt.% said carbon fiber and 0-30wt.% powder of a metal, such as stainless steel, iron or copper, having a particle diameter of 1.0-300mum. This composition is melt- kneaded and molded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a component material for a watch using a resin composition in which a thermoplastic resin is reinforced with a graphitized material of vapor grown carbon fiber containing acidic functional groups.

[Conventional technology]

Conventionally, the constituent material for watches was WC-Co as an exterior member.
In recent years, practical research using powdered SUS and powdered Tt is known. Furthermore, as a constituent material for watches whose basic composition is thermoplastic resin, which has excellent mechanical strength, abrasion resistance, chemical resistance, and thermal properties, for example, Japanese Patent Publication No. 55-45576 discloses glass fiber,
Alternatively, high-strength constituent materials for watches have been disclosed in which thermoplastic resin is filled with metal fibers, metal powder, etc.

[Problem to be solved by the invention]

The constituent materials for watches manufactured using conventional powder molding and sintering have a high hardness (HV1300) that cannot be easily obtained using ordinary metals such as carbide cases, but at the same time, they offer greater flexibility in terms of design. restrictions are very large. In addition, materials using powdered SUS or powdered Ti, which are currently undergoing practical research, can reach up to 98% of the theoretical density by molding using the HIP method, but they do not suffer from cavities or uneven filling. However, research into the surface of the constituent materials for watches reveals that countless bits appear, making it impossible to obtain the metallic luster and corrosion resistance required of the constituent materials, and furthermore, the design aspect of molding is difficult. It has many drawbacks, such as very large restrictions on the degree of freedom, and has not been put into practical use.

Furthermore, a thermoplastic resin filled with glass fiber, metal fiber, metal powder, etc. has high strength, but if the molecular weight of the thermoplastic resin is large, the fluidity of the resin will be poor and the surface texture will be poor. In order to improve fluidity, selection of resin with low molecular weight,
Alternatively, the fluidity is improved by adding a lubricant, etc., but even though the fluidity is improved, resin compositions improved in this way induce flaking during injection molding and have a reduced mechanical strength. Furthermore, the method of improving fluidity by adding a metal with high specific gravity such as tungsten poses a practical problem since high specific gravity metal powder such as tungsten is an extremely expensive metal powder.

The present invention solves these problems by using a high molecular weight thermoplastic resin, which is highly filled with vapor grown carbon fiber and metal powder, and has high strength and fluidity, and has a surface texture. An object of the present invention is to provide a composition for a timepiece component, which can be manufactured at low cost and has a high commercial value.

[Means to solve the problem]

The present inventors have so far discovered graphitized vapor grown carbon fibers (hereinafter referred to as VCC) having acidic functional groups as a new carbon material.
We have been conducting research on the development of F-AC (abbreviated as F-AC) and the characteristics and reactions of this material.We focused on the unique morphology and chemical properties of this fiber, thermal stability, and light resistance, and conducted various practical tests. During our research, we found that this VGCF-AC has excellent shape, aggregation state, and dispersion state in other substances.
The inventors have discovered that the AG resin composition is a constituent material for watches that has improved dimensional stability and weather resistance, does not deteriorate or discolor, and maintains strength for a long period of time, and has thus arrived at the present invention.

That is, the present invention uses a thermoplastic resin of 20 to 70% by weight, a fiber diameter of 0.01 to 4μ-1, an acidic functional group of 3 to 500μeq/
This is a constituent material for a watch, characterized in that it is made of a resin composition consisting of 5 to 50% by weight of graphitized vapor grown carbon fiber having a weight ratio of 5 to 50% by weight and 0 to 30% by weight of metal powder.

In the present invention, VCCF-AC has a diameter of 0.01 to
4 μm edge, preferably 0.01 to 2 μm, particularly preferably 0.01 to 1 μm, most preferably 0.01 to 4 μm, and the length of the fiber is not particularly limited.
Generally, the length is less than 5000μ, but it may be even shorter.
It may be 1000 .mu.m, 100 .mu.m, or 1.0 .mu.m (or even shorter) (fiber-like material obtained by crushing, cutting, or pulverizing, or granular or regular-shaped material may also be used).

In the present invention, the purity of carbon is high, generally 98.5
% or more, particularly 99% or more, most preferably 99.5% or more.

In addition, in the present invention, VCCF-AC is a highly graphitic substance, and among these, in structural analysis by X-ray diffraction, the lattice constant Co in the graphite crystal structure is 6.8.
8 or less, preferably 6.86 or less,
Particularly preferred is a range of 6.80 to 6.70, most preferred is a range of 6.78 to 6.72.

In the present invention, VCCF-AG is obtained by heat-treating vapor-grown carbon fiber at high temperature in an inert gas atmosphere. The temperature is 2000'C or more, and the most preferable range is 2100 to 3000C.

In the present invention, VCCF-AC is defined as having 3 acidic functional groups.
~500 Ijeq/g. The amount of acidic functional groups is preferably between 10 and 300 μeq/g, especially between 50 and 300 μeq/g.
The range is 15011 eq/g.

The most common method for producing VCCF-AC according to the present invention is to oxidize vapor-grown carbon fiber graphitized material with an oxidizing gas such as oxygen or an oxidizing agent such as nitric acid.
In addition, a plasma method, a graft method, etc. may also be used.

The constituent material of the watch of the present invention has a composition ratio of VCCF-AC of 5.
~50% by weight, preferably 10-40% by weight, particularly preferably 10-35% by weight.

If it is less than 5% by weight, the strength will not improve, and if it is more than 5% by weight, the strength will improve, but it will take a long time to improve the dispersion state, which will be disadvantageous in terms of cost, and the fluidity when melting the resin will decrease, resulting in poor moldability. spoil.

The constituent materials for watches of the present invention include crystal nucleating agents, thickeners, flame retardants, diluents, stabilizers, antioxidants, lubricants, fillers, and good release properties from molds during molding. It may contain various known seasoning agents, such as additives for.

In the present invention, the thermoplastic resin is preferably a polyamide resin such as nylon 6 or nylon 66, a polyester resin such as a polyacetal resin, a polyethylene terephthalate, a polycarbonate resin, or an ABS resin with a high molecular weight. Low molecular weight materials have poor Vickers hardness and are not suitable for watch components.

Among thermoplastic resins, polyamide resins with excellent mechanical properties are preferred, and nylon 66 resins are more preferred, and even nylon 66 resins with molecular weights in the range of 15,000 to 45,000 are used. Preferably, the molecular weight is 20.0.
00-40. OOQ, most preferably 25.00
It ranges from 0 to 35,000. Molecular weight is 15,
Nylon 66 resin with a molecular weight of 3145.000 or higher has excellent fluidity, but the mechanical strength does not reach the required physical properties, and the picker's hardness is low, making it unsuitable for watch component parts. Although it has excellent mechanical properties, it has poor fluidity and is difficult to injection mold.

In the present invention, the composition ratio of the thermoplastic resin is 20 to 7
0% by weight, preferably 20-60% by weight, particularly preferably 25-60% by weight, most preferably 30-60% by weight
It is.

In the present invention, metal powder has a particle size of 1.0 to 300.
Atrr stainless steel, iron, copper, etc. are preferred;
The composition ratio is 0 to 30% by weight, preferably 0 to 25% by weight,
Particularly preferred is 0 to 20% by weight.

In the composition for a watch component of the present invention, various known compounding agents such as a flame retardant, a stabilizer, an antioxidant, a lubricant, and an additive for improving mold releasability from a mold during molding are used. May contain.

When producing the composition for a watch constituent material of the present invention, first, the resin and the present VCCF-AC1 metal powder are blended to ensure uniform dispersion. The blending method may be tri-blending, wet blending, or impregnation blending, and is not particularly determined.

For the triblend, use a stirrer such as a Henschel mixer, and set the stirring time and rotation speed to the resin powder and VCCF-AC1.
It is arbitrarily set so that the metal powder is mixed uniformly. At this time, it is effective to use a resin powder with a particle size of one size or less. Further, in wet blending, first, a liquid that does not dissolve the resin, such as water or alcohol, is placed in a stirrable container, and VCCF-AC1 metal powder is added thereto and stirred to form a slurry. Next, a predetermined amount of a desired type of resin powder is added to this slurry and further stirred.

This slurry is then filtered and dried. moreover,
The impregnated blend consists of resin and VC previously dissolved separately in a solvent.
, CF-AG, and metal powder are mixed and stirred, and then the solvent is removed and dried. For melt-kneading thermoplastic resins, a kneader such as a Banbury mixer, a kneader roll mill, or a screw extruder can be used. In this way, by melt-kneading the pre-blended composition, it is possible to obtain a uniformly dispersed composition for a watch component material.

In this melt-kneading process, it is common to first form a pellet-like product and then use it for molding. The composition thus obtained can be used to manufacture a watch component material of a desired size by injection molding.

Furthermore, it is formed into a sheet-like or film-like intermediate product by extrusion molding, calendar molding, etc., and then manufactured as a watch component material by vacuum molding, etc.

The constituent material for watches manufactured in this way becomes a material with a black color and a high-class image. In addition, since VCCF-AG is acicular and has a minute fiber diameter of 0.01 to 4.0 Bes, PA
Unlike resin compositions such as N-CF and glass fiber, it does not protrude from the surface and has a rough surface roughness, and has a good texture.
CF-AG is a constituent material for watches that is also conductive and stain-resistant.

〔Example〕

The present invention will be explained in more detail below using Examples and Comparative Examples.

In addition, each characteristic value in Examples and Comparative Examples was measured according to the following method or JIS standard.

Tensile strength; JIS K-6810 bending strength
; JIS K-6810 flexural modulus; JIS
K-6810 Bits hardness: Determined by the following method using a Vickers hardness tester (Akashi Seisakusho type).

Test load (0.3 kgf) when indenting the test surface using a diamond square pyramid indenter with a facing angle of 136 degrees
) and the surface area of the depression determined from the diagonal length of the depression.

Test load 0.3 kgf Holding time 15 seconds θ F = Surface load 0.3 kgd) S = <Surface area of depression nnn” d = < Length of diagonal of depression θ = Opposite angle of diamond indenter Example 1 Diameter Vapor grown carbon fiber (tris acetylacetonate iron and benzene at 1400°C) with a diameter of 0.05 to 0.1 μm
(synthesized in a floating state) at 2400°
C, heat treatment under argon flow, carbon content 99
% and a lattice constant of 6.75 was obtained. This graphitized product was oxidized with nitrogen gas containing 0.7% oxygen to obtain VCCF-AC having an amount of acidic functional groups of 136 μsq/g. , :(7
) VCCF-AG was slightly crushed to facilitate dispersion to obtain VCCF-AG having a fiber length of substantially 5 μm or more (as observed using an electron microscope). 250g of this VCCF-AC
and 650 g of a polyamide resin (Leona, type 1.50O3 (trade name of Asahi Kasei Industries), molecular weight 33,000, which was cold-pulverized and adjusted to an average particle size of 50 μm, were mixed for 5 minutes in a Henschel mixer to obtain a composition. 100g of stainless steel metal powder with an average particle size of 80μ was added to the material, mixed and dispersed for another 2 minutes, and the resulting composition was mixed with P
It was pelletized using a CM30 twin-screw extruder. After further drying the pellet, the pellet was injection molded using a KC-20 injection molding machine manufactured by Yoro Iron Works Ltd. at an injection temperature of 320 DEG C. and a mold temperature of 85 DEG C. to prepare a test piece, and various physical properties were measured.

The results are shown in Table 1.

Example 2 350 g of VCCF-AG, 550 g of polyamide resin
A test piece was prepared in the same manner as in Example 1 except that the blended amount was changed to 100 g of stainless steel powder, and the physical properties were evaluated.
The results are shown in Table 1.

Example 3 450g of VCCF-AC and 550g of polyamide resin
A test piece was prepared in the same manner as in Example 1, except that the blending amount was changed, and the physical properties were evaluated.

The results are shown in Table 1.

Comparative Example 1 Polyamide resin (Leonatype 15 used in Example 1)
A test piece was prepared and evaluated using the method of Example 1. The results are shown in Table 1.

Comparative Example 2 Glass fiber (fiber diameter 9μl, fiber length 3+n+a)
A test piece was prepared and evaluated using the method of Example 1, using 350 g of polyamide resin, 550 g of polyamide resin, and 100 g of stainless metal powder. The results are shown in Table 1.

From the results in Table 1, the mechanical properties of the test piece made with the VGCF-AC mixed composition are improved by several steps in terms of tensile strength, bending strength, and bending elastic modulus, compared to Comparative Example 1, which is made only of nylon resin. In addition, a comparison between a test piece made with a composition containing 35% glass fiber and Example 2 showed that the mechanical properties were excellent, and even in terms of Vickers hardness, VCCF-AC,
It can be seen that the resin composition contained therein is excellent.

(The following is a blank space) Table 1 [Effects of the Invention] The watch constituent material of the present invention has the following effects at least as a watch constituent member.

VCCF-AC has a decorative appearance, can be made lightweight by synthetic resin molding, and has a clean surface and good feel.
Reinforcement by the diameter of fine fibers has been strengthened, making it possible to perform fine injection molding not only for watch exterior parts, but also for interior parts (e.g. gear shafts, etc.).■GCF-AC's conductivity prevents static electricity, making it ideal for watch manufacturing and assembly. It also has a stain-preventing effect and is an optimal material in terms of cost.

Claims (1)

[Claims] 1. Thermoplastic resin 20-70% by weight, fiber diameter 0.01-
4 μm, 5 to 50% by weight graphitized vapor grown carbon fiber having acidic functional groups 3 to 500 μeq/g, 0 metal powder
A constituent material for a watch, characterized in that it is composed of a resin composition consisting of ~30% by weight.