JPS6069158A - Electrically conductive, low-shrinkage resin molding material - Google Patents

Abstract

PURPOSE:To provide the titled resin molding material which has good moldability and gives moldings having excellent electrical conductivity and mechanical strength, by blending a small quantity of a specified electrically conductive material with a low-shrinkage resin compsn. contg. an unsaturated polyester resin as a base. CONSTITUTION:Finely divided electrically conductive carbon black having a specific surface area of 500m<2>/g or above such as Ketjen black EC having a specific surface area of 1,000m<2>/g or above (a product of Lion-Akzo K.K.) is used as an electrically conductive material. 0.5-5wt% (based on the total quantity of molding material) said electrically conductive material is blended with a low- shrinkage resin compsn. consisting of an unsaturated polyester such as Upika 7500 (a product of Nippon Upika K.K.), a low-shrinking agent such as a styrene soln. of polymethyl methacrylate, a reinforcing agent such as chopped glass strand having a diameter of several tens of microns, a filler such as aluminum hydroxide and a polymn. initiator such as butyl perbenzoate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a conductive material with good conductivity and moldability by blending a small amount of conductive fine carbon black into a low-shrinkage resin composition having an unsaturated polyester resin as a substrate. This invention relates to low-shrinkage resin molding materials.

Conductive resin compositions or conductive resin molding materials are used in the semiconductor industry in the form of compounds, pastes, molded products, etc., as materials for packaging, storage, and transportation to prevent electrostatic damage, and for antistatic and static electricity removal purposes. flooring, shielding to prevent electromagnetic interference.

It is used in a wide range of fields, including electric wire coatings and synthetic resin thermistors to prevent corona discharge deterioration.

Such conductive resin compositions include conductive particles such as carbon black and graphite, metal powders, metal flakes, carbon fibers, metal fibers, etc., as substances that impart conductivity to thermoplastic resins. Products containing fibrous materials singly or in combination are known. For example, devices such as electronic devices and LSIs are rolled up, which is extremely sensitive to static electricity, and a conductive resin composition containing a large amount of conductive carbon black in a thermoplastic resin has been proposed as a packaging material for these devices. Since it is a thermoplastic resin, its molded products have poor heat resistance, and its range of use is limited.

By the way, the thermosetting resin molding material FiEIMO is made by blending a reinforcing material, a filler, and a polymerization initiator with a thermosetting resin.
, BM○, etc. can be molded by methods such as injection molding, compression molding, and transfer molding, and the molded products have higher heat resistance than thermoplastic resins, so they can be used for structural members. Are known. In such thermosetting resin molding materials, unsaturated polyester resin, which is a typical thermosetting resin, has many advantages that other resins do not have, but it has the disadvantage of causing volumetric shrinkage during curing.

Therefore, precision molded products that require dimensional accuracy, such as
It is not suitable for molding parts for electronic equipment, copying equipment, etc.

On the other hand, as an unsaturated polyester resin that does not cause curing shrinkage, a low-shrinkage resin that is a blend of an unsaturated polyester resin with a low-shrinkage agent has been developed, and a low-shrinkage resin molded by blending such a resin with a reinforcing material, a filler, and a polymerization initiator. The materials are also known. However, a conductive low-shrinkage resin molding material imparted with conductivity is not known.

Generally, in order to obtain a conductive resin by blending a conductive substance into a synthetic resin, it is necessary to blend a large amount of the conductive substance. It is known that there are problems such as a decrease in the mechanical strength of the product.

In view of the above-mentioned problems, the present inventors have determined that by blending a small amount of conductive substance into a low-shrinkage resin composition having an unsaturated polyester resin as a substrate, the composition exhibits good conductivity, improves molding processability, and improves molding properties. We conducted various studies and studies on new conductive low-shrinkage resin molding materials with excellent mechanical strength and other properties.

As the conductive substance for imparting conductivity, as mentioned above, conductive particles such as carbon black and graphite, metal powder, metal flakes, or fibrous materials such as carbon fiber and metal fiber are used. However, conductive carbon black has the advantage that it has less influence on moldability than other conductive substances, and can be made into a molding material with arbitrary conductivity by adjusting the amount added. Because of this, it is widely used. The conductive mechanism when conductive carbon black is blended with resin is as follows.
It is necessary for the carbon black particles to form a chain structure or to be close to each other within a distance of several 1 h, and the particle size is generally small, and there is little hydrogen or oxygen adsorbed, and in addition, it is necessary to It is said that those with advanced chemical conversion are preferable. Acetylene black is known as one that satisfies these requirements. However, although acetylene black has a small surface area and can be easily dispersed in a resin, it is necessary to blend it in a large amount in order to sufficiently improve conductivity. Furthermore, it is said that the conductivity of acetylene black decreases due to changes in the carbon structure during the crosstalk process with resins, reinforcing materials, fillers, etc.

The present inventor has proposed that, among such conductive substances, conductive fine particles of carbon having several times higher conductivity than acetylene black can be incorporated into a low-shrinkage resin composition having an unsaturated polyester resin as a substrate. Black is preferable, and it has a large surface area compared to the particle size, and when acetylene black has a surface area of 500 dl"1 or more, compared to 100 m'/f or less, by adding a small amount, excellent conductivity can be achieved. The present invention was completed by discovering the fact that there is no reduction in conductivity due to crosstalk, no undesirable effects on molding, no reduction in strength of molded products, and no special treatment is required in the formulation.

That is, the present invention uses an unsaturated polyester resin as a substrate,
A low-shrinkage resin composition containing a low-shrinkage agent, a reinforcing material, a filler, and a polymerization initiator has a surface area of 500rr? /
The present invention relates to a conductive low-shrinkage resin molding material characterized in that it is blended with conductive fine particulate carbon black of f or more.

The unsaturated polyester resin used in the present invention has various characteristics and uses depending on its raw material. That is, the raw materials include fatty acid unsaturated polybasic acids such as maleic anhydride and fumaric acid, aromatic saturated polybasic acids such as phthalic anhydride and inphthalic acid, and aliphatic saturated polybasic acids such as succinic acid and adipic acid. Polybasic acids and propylene glycol, diethylene glycol, triethylene glycol, 1.3-
A commercially available liquid resin with general performance obtained by polycondensing an alkyd resin obtained by polycondensing polyhydric alcohols such as butylene glycol with a polymerizable vinyl monomer such as styrene or vinyltoluene, or a het acid as a raw material. There are flame-retardant resins made from polyester, heat-resistant resins made from diallyl phthalate, and any of these liquid unsaturated polyester resins may be used.

In the conductive low-shrinkage resin molding material of the present invention, the conductive substance blended into the low-shrinkage resin composition has a surface area of 500 m'/
f or more, preferably 800? ? ! It is a conductive fine carbon black with a conductivity of /f or more. Carbon black with a large surface area is porous and highly structured, and the particle density decreases, so the number of particles increases at a constant weight ratio. The distance between them can be reduced, and high conductivity can be imparted. Such conductive fine particulate carbon black has a surface area of 1000 rr? /f or more and can be suitably used. Incorporation of Ketjenblack ma, which has a large surface area, increases the modulus and viscosity of the resin composition, lowering the fluidity of the composition, and causing the water absorption and oil absorption properties of Ketjenblack WO to increase the modulus and viscosity of the resin composition. It is said that it is necessary to subject Ketjenblack EC to special treatment because it may cause non-uniform dispersion in the composition. By pre-mixing with materials, fillers, etc., and then blending with the resin, it can be easily blended without such treatment, and can be uniformly dispersed in the composition. In the present invention, it is sufficient that the amount of conductive fine carbon black in the low-shrinkage resin molding material is 0.5 to 5% by weight, since there is little change in the structure of the carbon black during crosstalk or molding. , does not affect the conductivity of the molded product. However, if the amount is too small, sufficient electrical conductivity cannot be obtained, so it is preferable that the amount is 0.7 to 3% by weight in the low shrinkage resin molding material. In addition, in conductive fine carbon black having a surface area of 500 m'/f or more, for example, if a large amount of Ketjenblack 11IO is blended in an amount exceeding the above range, it is possible to
Although this may approach the electrical resistance value of the 1IO material, it will have unfavorable effects on moldability or properties of the molded product. Surface area 500m”/f
In the case of the following conductive fine-grained carbon black, it is natural that a large amount must be added, which may result in non-uniform dispersion or have unfavorable effects on moldability, properties of molded products, etc. give. Surface area 500rr? /f
Other conductive substances may be combined with the conductive fine-grained carbon black described above to the extent that they do not impair moldability or properties of the molded article (9).

In such a case, as is clear from the Examples described later, the conductivity is slightly improved, but it is not particularly significant.

In the low-shrinkage resin composition using the unsaturated polyester resin as a substrate of the present invention, examples of the low-shrinkage agent to be added to the unsaturated polyester resin include thermoplastic resins such as polymethyl methacrylate, polystyrene, polyvinyl acetate, and polycaprolactone. to styrene monomer at 30 to 50 parts
Examples include solutions in which t% is dissolved. Such a low shrinkage agent is included in the resin component consisting of an unsaturated polyester resin and a low shrinkage agent.
It is preferable to mix 0 to 20% by weight.

Reinforcing materials added to the resin component consisting of unsaturated polyester resin and low shrinkage agent include glass fibers such as chopped strands and milled fibers, nylon, acrylic, vinylon, and vinylidene.

Organic fibers such as fluorine-based fibers, silicone carbide fibers,
A fibrous material having a diameter of several tens (10) microns, such as boron fiber or asbestos, is preferable, and a fibrous material having electrical conductivity, such as carbon fiber, aluminum fiber, or stainless steel fiber, may also be used. Furthermore, it may be a flake-like material, regardless of whether it is conductive or not. Moreover, they may be surface-treated, for example, with a coupling agent, for the purpose of improving adhesion with resin and dispersibility.

The filler is not particularly limited as long as it is blended into the low-shrinkage resin component having an unsaturated polyester resin as a substrate and does not cause any undesirable effects, such as aluminum hydroxide or alumina.

Calcium carbonate, wollastonite, talc, diatomaceous earth,
Known fine powders such as clay, kaolin, mica, and glass powder can be used. Such fillers may contain other additives as necessary, such as flame retardants, flame release aids, mold release agents, thickeners,
Weather resistance improver 9 A coloring agent and the like may also be mixed together. As the flame retardant, known flame retardants such as bromine type, chlorine type, phosphoric acid type, etc. may be used, but preferred are beam/acid type phosphoric acid (11) ammonium, tricresyl phosphate, triethyl phosphate, acidic phosphate ester, etc. . Flame retardant aids include antimony trioxide and magnesium hydroxide. Metal soaps, such as stearic acid-based ones, are preferably used as the mold release agent blended for the purpose of improving the mold release properties during molding of the low-shrinkage resin composition.

Thickeners used to adjust the viscosity of low-shrinkage resin compositions, depending on their dispersibility or workability during molding, include magnesium oxide, magnesium hydroxide, calcium oxide, and hydroxide. Calcium etc. are used alone or in combination.

The polymerization initiator is selected from those known as radical polymerization initiators for unsaturated polyester resins, such as organic peroxides and azobis compounds, and the organic peroxides have a moderate decomposition temperature of 90 to 110°C. Preferably. Further, accelerators such as cobalt naphthenate and dimethylanilide can also be used in combination.

(12) In the low-shrinkage resin composition using the unsaturated polyester resin of the present invention as a substrate, the respective blending amounts of the resin component consisting of the unsaturated polyester resin and the low-shrinkage agent, the reinforcing material, the filler, and the polymerization initiator are Selected from within a known range. Usually, the reinforcing material in the low shrinkage resin composition is 5 to 20% by weight, the filler is 50 to 80% by weight, and the polymerization initiator is 0.1% by weight.
~3 weight class. In such formulations.

It may not contain reinforcing material or filler.

Surface area of 500 tr for low shrinkage resin composition with unsaturated polyester as substrate? /f or more conductive fine carbon black, such as Ketjenblack me (trade name:
The method of blending Ketjenblack No. 1 into a pre-prepared low-shrinkage resin composition is as follows:
- It is not limited to the method of blending. A preferred blending method is a method of blending Ketjenblack FiO when blending a low shrinkage resin composition having an unsaturated polyester resin as a substrate. That is, (13) a method in which a predetermined amount of Ketjenblack EC is mixed in advance into a powdered filler. By taking such measures, non-uniform dispersion due to agglomeration of the resin due to contact with the liquid resin due to the water absorption and oil absorption properties of Ketjenblack EC can be prevented.

A surface area of 500W for a low shrinkage resin composition based on unsaturated polyester? After blending conductive fine carbon black of /f or more, or a resin component consisting of an unsaturated polyester resin and a low shrinkage agent, a reinforcing material, and a surface area of 500 rr?
After blending a filler containing conductive fine carbon black of /f or more and a polymerization initiator, the conductive low-shrinkage resin is molded into a putty by mixing the wires using a mixer such as a kneader or panburi mixer. materials can be obtained. For example, in the case of acetylene black, for example, if the crosstalk time is extended, the structure of the carbon black changes and the conductivity of the molded product decreases, but this problem does not occur in the present invention. 04) Therefore, the crosstalk time is not particularly limited, but it is preferably 5 to 20 minutes from the viewpoint of workability.

The conductive low shrinkage resin molding material of the present invention is BMO.

In a form such as BMO, it can be molded by an appropriate molding method such as injection molding, compression molding, or transfer molding. The specific resistance of the molded product is 101
104, and can be suitably used as precision structural members for electronic communication and copying equipment that require antistatic and antistatic properties.

EXAMPLES The present invention will be specifically explained below using Examples, but the present invention is not limited to these Examples.

Examples 1 to 4 1 Iupica 7500” (unsaturated polyester resin)
Product name: Nippon Yubika Co., Ltd.) Styrene monomer solution 1 Yupicam-8 of polymethacrylic resin as a low shrinkage agent
0" (product name: Nihon Yupi Rikisha product), reinforcing material: Chopped Strand 05) (Asahi Fiberglass Co., Ltd. product), aluminum hydroxide as a filler, zinc stearate as a mold release agent, thickener A mixture of magnesium oxide, tertiary-butyl perbenzoate as a polymerization initiator, and 6-button black mo' (trade name: Lion Akzo product) as a conductive fine-grained carbon black with a surface area of 500 n179 or more.
Weigh out the mixture according to the proportions shown in the table, mix the filler, conductive fine carbon black, and polymerization initiator in advance, blend it with the resin component consisting of unsaturated polyester resin and low shrinkage agent, and kneader at room temperature. Approximately 10 minutes per kneader
After kneading for a minute, a reinforcing material was further added and kneaded for about 5 minutes to obtain a putty-like conductive low-shrinkage resin molding material. This conductive low-shrinkage resin molding material was molded at 140°C using a compression molding machine.
− A molded product was created. The blending dispersibility of the molded product created in this way was investigated by visual inspection, and the specific resistance was measured using a Wheatstone bridge (manufactured by Yokotsutsu Electric: Type 276).
9). 16) Furthermore, as a durability test, a humidity test was conducted at 40°C x 100cm RH for 7 days, and the specific resistance was measured in the same manner as above.
The results are shown in Table 1.

Table 1 Yellow 1) Contains low shrinkage agent 40% St. .

Yellow 2) Breakdown, mold release agent 2.0. Thickener 0.1. Filler 55
．． 4 to 56.9 (each weight %) Separately, 0.8 weight percent of polymerization initiator was added to the entire composition.

(17) Examples 5 to 8 Example 1 except that the filler in Examples 1 to 4 was used in combination with conductive aluminum coated glass fiber, carbon fiber, or aluminum ζ flakes at the blending ratio shown in Table 2. A conductive low-shrinkage resin molding material was obtained in the same manner as in 4 to 4, molded products were prepared, and their visual inspection and specific resistance after molding and durability tests were measured.

The results are shown in the second page.

(18) Table 2 +1) Contains 40% by weight of low shrinkage agent.

Bitter 2) Breakdown: Aluminum coated glass fiber 10.0. Mold release agent 2.0° Thickener 0.1. Filler 45.9-46.4Cf
ii) 0.8% by weight of polymerization initiator based on the total composition
combination.

Yellow 3) Breakdown, carbon fiber 6. O9 mold release agent 2.0. Thickener 0
．． 1° filler 49.9 (each weight 96) and polymerization initiator 0.8 weight based on the total composition.

+4) Breakdown: aluminum flakes 10.0. Mold release agent 2.
0° Thickener 0.1. The amount of polymerization initiator was 0.8% by weight, based on the total composition of each filler (45.9% by weight).

(19) Comparative Examples 1 to 4 In Examples 1 to 4, the conductive fine particulate carbon black with a surface area of 500 m''/f or more is not blended at all, or a large amount is blended, or the conductive carbon with a surface area of 500 n?/f or less A conductive low shrinkage resin molding material was obtained in the same manner as in Examples 1 to 4, except that black acetylene black (manufactured by Denki Kagaku Co., Ltd.) was used, and a molded product was created.
Their appearance was inspected and their specific resistance after molding was measured.

The measurement results are shown in Table 3. The surface area of conductive substances is 5
00fr? Acetylene black, which is a conductive carbon black with a conductivity of less than /f, has poor conductivity and a surface area of 5
Even in Ketjenblack EC, which is a conductive fine carbon black with a particle diameter of 00 m'/f or more, it is clear that other properties will be impaired if a large amount is added.

@) Table 3 1) Contains 40% by weight of low shrinkage agent.

Yellow 2) Breakdown, mold release agent 2.0. Thickener 0.1° Filler 52
．． 9 to 57.9 (each weight): 0.8 weight amount of polymerization initiator to the total composition (3) Acetylene black.

Yellow 4) Ketjen Black EC0 (21)

Claims (1)

[Claims] 1. Add conductive fine particles of carbon black with a surface area of 500 m'/7 or more to a low-shrinkage resin composition made of an unsaturated polyester resin as a substrate and a low-shrinkage agent, a reinforcing material, a filler, and a polymerization initiator. A conductive low-shrinkage resin molding material characterized by being made by blending it.