JPS61278566A - Electrically conductive thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To provide the titled compsn. which has excellent mechanical strength and stable (semi)conductivity, by blending an electrically conductive potassium titanate fiber, electrically conductive carbon black and glass fiber and/or carbon fiber with a thermoplastic resin. CONSTITUTION:10-30wt% electrically conductive, single-crystal potassium titanate fiber having an average fiber diameter of 0.01-1mum, an average fiber length of 1-100mum and an aspect ratio of 10 or above, 0.3-5wt% electrically conductive carbon black (e.g. furnace black), 5-30wt% glass fiber (e.g. alkali- free glass) and/or carbon fiber having a fiber length of 0.1-10mm and optional additives such as thermal stabilizer, light stabilizer, plasticizer (e.g. impact modifier), lubricant, flame retarder, colorant, pigment, etc. are blended with a thermoplastic resin (e.g. PE).

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a conductive thermoplastic resin composition having excellent mechanical strength and other mechanical properties. More specifically, the present invention relates to thermoplastic resins that have stable conductivity or semiconductivity and have excellent mechanical performance, which can be used in the fields of precision mechanical parts, electrical parts, and electronic devices having complex shapes. Regarding the composition.

(Background and issues) In recent years, as technology has become more sophisticated and precise, there has been an increasing demand for various devices and their component parts to be lighter, thinner, and smaller in terms of materials and structure. This is especially noticeable in the fields of electronic materials and electronic equipment, and the phenomenon is rapidly progressing that parts and members that were made of metal until yesterday are now being replaced with plastic.

However, on the other hand, various problems such as mechanical strength and other mechanical properties, antistatic performance and conductive performance, which did not pose problems with conventional metal parts and members, have become apparent, and it is necessary to solve these problems in each field. Research is being actively carried out.

By the way, in order to improve the low Young's modulus and other low mechanical strength that can be said to be the fate of plastics, one effective solution is to incorporate a fibrous reinforcing agent into plastics.

On the other hand, as a method for imparting antistatic performance.

There is a method of adding a compound having a parent group such as a polyhydric alcohol, a fatty acid ester of a polyhydric alcohol, a polyalkylene glycol, or an alkylamine. however,
With this method of adding a hydrophilic substance, the surface resistance of the resin molded product can only be reduced to about 1011Ω at most, and the resistance value changes significantly depending on the environmental humidity.Another method is to use conductive carbon black. There is also a method of blending it into the resin. However, as is well known, conductive carbon black has the disadvantage that it is very bulky and easily scatters when handled, making it easy to pollute the workplace. Moreover, in order to impart conductivity to the resin composition using quartz alone, it is necessary to add at least about 10% by weight. However,
Blending 7% by weight or more of conductive carbon black significantly reduces the mechanical strength of the target molded product. Therefore, the scope of its application is naturally limited to a relatively narrow range, but the biggest drawback in particular to resin compositions that have been given conductivity by adding conductive carbon black alone is that they do not have a reproducible specific resistance value. This is difficult to apply to the target resin composition.

To explain this in more detail, a resin composition containing 7% by weight of conductive carbon black exhibits a high electrical resistance value inherent to thermoplastic resins, but
On the contrary, resin compositions to which the former is added at a ratio of 10% by weight or more exhibit a low resistance value inherent to conductive carbon black, and in the intermediate region of 7% by weight or more and less than 10% by weight, the resistance value decreases. It changes very subtly as the amount of conductive carbon black added increases. Therefore, it is extremely difficult to freely and stably provide a design resistance value intermediate between the resin specific resistance value and the specific resistance value of conductive carbon black. In other words, a slight change in the amount of conductive carbon black mixed can cause the electrical properties of the compound or molded product made from it to change rapidly from an insulating region to a low resistance region, so it is difficult to consistently impart the desired semiconductivity. In addition, the blending of conductive carbon black deteriorates the thermal stability of the blended resin, and thermal decomposition that occurs during molding significantly changes the appearance of the resulting molded product. This causes many drawbacks, such as a significant drop in impact resistance and bending strength.

As a means to solve the above problems, we used conductive potassium titanate (hereinafter referred to as "conductive PTWJ"), which was previously discovered by the present inventors and has been given conductivity as a fibrous reinforcing agent. However, in order to obtain the desired high conductivity, the conductive PTW must be
It is necessary to mix at a high filling rate level of about % or more.

On the other hand, when molding small parts with a product weight of 10 mg to 1 g, parts with thin parts with a wall thickness of 0.5 mm or less, parts with sharp edges such as gears, glass fiber or carbon If a composition containing mB alone is used, the reinforcing material will not be sufficiently distributed in narrow areas such as thin wall parts and tooth tips, and a sufficient reinforcing effect will not be obtained, resulting in insufficient strength and rigidity. Moreover, warping occurs due to anisotropy based on the orientation of the reinforcing material, and furthermore, surface roughness increases, making precise molding difficult.

(Purpose of the invention) The present invention provides practically sufficient mechanical strength and other mechanical properties (
The object of the present invention is to provide a thermoplastic resin composition that has the following "mechanical properties" (hereinafter referred to as "mechanical properties"), maintains a smooth surface, and can stably exhibit desired electrical conductivity in a molded object. .

(Structure of the Invention) In order to achieve the above object, the resin composition of the present invention includes:
The composition contains 010 to 30% by weight of conductive potassium titanate Fa fibers, 00.3 to 5% by weight of conductive carbon black, and 05 to 30% by weight of glass fibers and/or carbon fibers. It is characterized by being

As a result of various research aimed at solving the above-mentioned problems, the inventor of the tree added 0.10 to 30% by weight of conductive PTW and 0.3 to 5% by weight of conductive carbon black to a thermoplastic resin. A conductive thermoplastic resin composition containing 05 to 30% by weight of glass m fibers and/or carbon fibers,
Depending on the blending ratio and amount of conductive PTW, conductive carbon black, glass m fiber and/or carbon tan, arbitrary conductivity can be imparted to the molded object with good reproducibility, and the above composition. Surprisingly, the properties of the conductive PTW can be fully exhibited in the molded object with a filling amount of the PTW that is lower than when the conductive PTW is used alone, and therefore, this composition is economical. It has also been found that the conductive resin composition is extremely advantageous for the following purposes.

According to the new findings obtained by the present inventors, by using conductive PTW, conductive carbon black, glass fiber and/or carbon fiber together within the above-mentioned quantitative range, the resistance value is much higher than the expected value. Not only is it lower, but in the semiconducting region,
Stable electrical resistance values without variations can be easily reproduced,
Moreover, precise injection molding is possible even for molded products that require precise dimensional accuracy, such as those with thin walls or acute angles, and the resulting molded product reaches its end (a position far from the gate). It has a high uniform strength of 4=4 and also has excellent heat resistance. Therefore, according to the present invention, it is possible to uniformly manufacture molded products that require any desired conductive performance, high mechanical strength, and precise dimensions from an insulating range to a low resistance range.

The conductive PTW used in the present invention has the following general formula (I
), the average fiber diameter is 0.
．． 01 to 1 field, average fiber length 1 to 100 pm, and average fiber length/average fiber diameter ratio (aspect ratio) of 10 or more.

K2O・n(TiOz-X)...Φ(1) (In the formula, n means a real number of 8 or less, and X means a real number of less than 2.) This conductive PTW has the general formula, K20s n (TiOz) (In the formula, n is a positive real number of 8 or less) Potassium titanate whiskers represented by 500-
It is obtained by reductive firing at a temperature of 1500°C. Incidentally, examples of the carbon material used in this case include carbon black, graphite, coke, petroleum pitch, and the like. At this time, the mixing ratio of the potassium titanate whiskers and the carbon material varies depending on the size and material of the reduction furnace, but is usually in the range of 1 to 50% by weight relative to the potassium titanate whiskers.

In addition, as other conductive PTW, conductive or semiconductive substances such as metals and metal oxides are attached or deposited on the surface of potassium titanate whiskers by electroless plating, dipping, or spray coating. You can also use things. For reference, to electrolessly plate potassium titanate whiskers, place the whiskers in a plating solution of nickel, copper, platinum, silver, etc. in an alkaline range at 100°C for 50 minutes.
Soak and stir for 1 minute to 1 hour. In addition, in the spray coating method, an aqueous solution or an aqueous organic solvent solution of a halide, sulfate, or oxide such as tin, nickel, indium, or antimony is applied to potassium titanate whiskers heated to 200 to 900°C using a spray gun or the like. The whisker surface is coated by spraying and coating.

Each of the above conductive PTWs can usually be used in an untreated state, but in order to improve the interfacial adhesion with thermoplastic resins, surface treatments such as silane coupling agents and titanate coupling agents are applied depending on the purpose. The use of agents generally gives better results.

The above blending amount of conductive PTW is determined from the viewpoints of imparting conductivity, improving dimensional accuracy, and improving rigidity and mechanical strength.
It is preferably blended in the range of 10 to 30% by weight in the composition. If the blended amount is less than 10% by weight, the mechanical strength and conductivity of the thin walled part of the molded article cannot be sufficiently improved. Even if it is used in an amount exceeding 30% by weight, it is difficult to observe an effect of improving mechanical strength and increasing conductivity commensurate with the amount exceeding the limit amount.

The conductive carbon black used in the present invention includes:
Examples include furnace black, thermal black, channel black, and graphite. However, in particular, ■ stractures are likely to develop.

■ Small particle size.

■Large surface area.

■ There are few impurities that capture τ electrons.

■ Graphitization is progressing.

Among furnace blacks, Ketjen black, which is a member of the conductive 2 furnace blacks, is optimal when considering the performance required for conductivity.

The amount of conductive carbon black used in combination with conductive PTW is preferably within the range of 0.3 to 5% by weight in the composition depending on the target degree of conductivity and semiconductivity. If the amount used is 0.3% by weight or less, strutures sufficient to impart conductivity will not be formed in the resin, and therefore, the conductive P
Almost no effect can be expected when used in combination with TW.On the other hand, if the blending amount exceeds 5% by weight, not only will the mechanical properties of the molded product decrease significantly, but also the thermal stability of the resin composition will decrease.
In addition, the processability during granulation also deteriorates.

The glass fiber used in the present invention is SiO2, B20
3AI203. It is obtained from inorganic glass containing oxides such as CaO, Na2O, K2O, etc. Depending on the purpose, it can be used as alkali-free glass (E glass) or alkali-containing glass (
C glass), alkali-resistant glass (A glass), etc. are selected and used, but in terms of reinforcing effect, E glass, which is generally used for resin reinforcement, is preferable.The fiber length of these glass fibers is 0.1 to 1 (lsm
Chopped strands having a length of about 3 cm or 6 cm, which are usually used for resin filling, are particularly suitable.

The above glass fibers can be used in an untreated state, but for purposes such as those treated with a silane coupling agent such as aminosilane or epoxysilane, a chromium-based coupling agent, or a plastic-based sizing agent for the purpose of bundling the fibers. More suitable.

The carbon fiber m (carbon fiber) that can be used in the present invention may be acrylonitrile-based or pitch-based, and its Ia fiber length is preferably 0.1 = 10 mm. The 0-carbon #a female, which is preferably a chopped fiber with a length of about 3 to 6 inches, is also coated with various treatment agents such as epoxy resin, polyamide resin, etc. It is preferable to use a material treated with a polycarbonate resin or a polyacetal resin, or a surface oxidized with plasma or the like, but the surface treatment is not essential for the purpose of the invention.

The blending amount of glass m fibers and/or carbon mrta is preferably within the range of 5 to 30% by weight in one composition; if the amount of these fibers is less than 5 wt%, the strength improving effect is insufficient. be. Moreover, even if it is used in an amount exceeding 30% by weight, not only is it not possible to expect an effect of improving mechanical strength commensurate with the limit amount, but also the surface roughness of the molded product increases, and in addition, the composition This is not preferable because it becomes difficult to granulate the granulator and the granulator becomes more abrasive.

Thermoplastic resins in the present invention include general-purpose thermoplastics such as polyethylene, polypropylene, and polyvinyl chloride resins, as well as aliphatic polyamides, aromatic polyamides,
Includes all engineering plastics such as thermoplastic polyester, polyacetal, polyphenylene sulfide, polysulfone, polyetherimide, and polyetheretherketone.

The method of blending conductive PTW, conductive carbon black, glass fiber and/or carbon fiber with the above thermoplastic resin is arbitrary, and there is a method of tri-blending, a method of blending the thermoplastic resin melted using an extruder, etc. Known formulation methods such as mixing methods can be freely employed. However, in order to prevent or suppress the cutting of the conductive PTW fiber-carbon fiber glass fiber and the destruction of the conductive carbon black strafts during the cross-mixing process, it is necessary to use a mild kneading method, such as an extruder, to melt the thermoplastic. Conductive PTW, conductive carbon black in resin,
It is preferable to adopt a method of blending carbon fiber and glass TA fiber.

The resin composition of the present invention may further contain known impact-resistant agents such as heat stabilizers, light stabilizers, and plasticizers, lubricants, flame retardants, dyes or pigments, etc., as necessary. It can be added as desired within a range that does not impair the effects of the present invention.

(Examples) Examples of embodiments of the invention and specific effects of the invention will be described below using examples, but the examples are of course for illustrative purposes and are not intended to define the connotation or extension of the five inventive ideas. do not have.

Example! Polypropylene [Mitsui Toatsu Chemical ■; Noblen H3O
1], conductive p"rw made by reducing and firing potassium titanate whiskers at 1000°C in an inert atmosphere [manufactured by Otsuka Chemical ■], Ketjen Black EC-P [manufactured by Lion Akzo ■], and average fiber length 3■ Glass fiber!1 [manufactured by Shio Fiberglass Co., Ltd.; C303-MA497] in the table below-1
As the compounding composition shown in Fig. 2, the above conductive PTW, Ketjenblack EC-P and glass #Jl were mixed into the melted Noprene H3O1 in a 45mφ^ twin-screw extruder set at 220°C. It was extruded and granulated. Thereafter, injection molding was performed under the following conditions to create a test piece for measuring physical properties.

Cylinder temperature = 210°C Injection pressure 500 kg/c2 Injection time: 15 seconds Mold temperature: 60°C The electrical properties and mechanical strength of each test piece obtained were measured. The results are shown in Table 1 below.

(Left below) As is clear from the volume resistivity and bending strength shown in the table, the combination of conductive PTW and conductive carbon black provides excellent conductivity. A thin case with a width of 50 mm was injection molded, and it was confirmed that all of Examples 1-1 to 1-5 had good surface smoothness, no warping, and good dimensional accuracy.

Tomogorina Duracon M'fQ-02 [Polyplastic ■; Polyacetal], Conductive PTW same as Example 1 [manufactured by Otsuka Chemical], Ketjenblack E C-D J 500
[Made by Lion Akzo] Carbon rim with cross-sectional diameter of 9mm and average fiber length of 6mm! The conductive PT described above was added to the molten Duracon M90-02 using a 45+smφ twin-screw extruder set at 220°C with the compounding composition shown in Table 2 below.
W Ketjen Black EC-DJ500 and carbon fiber were mixed and extrusion granulated. Thereafter, injection molding was performed under the following conditions to create a test piece for measuring physical properties.

Cylinder temperature: 200°C Injection pressure 1000Kg/c+s2 Injection time + 30 seconds Mold temperature = 80°C Subsequently, electrical properties and mechanical strength were measured. The results are shown in Table 2 below.

(Margin below) Electrical properties and mechanical strength B [Measured with Jl [manufactured by Kyo Seimitsu] (R+aax).

As is clear from Table 2 above, when the blending amount of carbon m is less than 5% by weight, the effect of improving mechanical properties is small;
When it exceeds 0% by weight, the surface roughness becomes large and there is a tendency that it is not suitable as a molding material for precision molded products.

In addition, the pellet production (granulation) of Example 2-3 was quite difficult from the viewpoint of take-up properties.

Example 3 RENY6001 [Made by Mitsubishi Gas Chemical ■; Nylon MX
D6], conductive PTW obtained by mixing potassium titanate whiskers and coke and reducing and firing the mixture in a mixed gas flow of hydrogen gas and propane gas [manufactured by Otsuka Chemical ■]
and Ketjen Black EC-P [manufactured by Lion Axie], a glass chopped strand with a length of 3+u+ and a carbon am with a length of 6a+m as shown in Table 3 below, and a biaxial 45m+oφ set at 270°C. The above conductive PTW was added to the melted RENY6001 using an extruder.
Ketjenblack EC-P glass fibers and carbon fibers were mixed and extrusion granulated. Thereafter, injection molding was performed under the following conditions to create a test piece for measuring physical properties.

Cylinder temperature: 285°C Injection pressure: 1000 kg/cra2 Injection time: 20 seconds Mold temperature: 120°C The electrical properties and mechanical strength of the obtained test piece were measured. The results are shown in Table 3 below.

(Left below) As is clear from Table 3 above, conductive PTW10-20
Weight%, conductive carbon black 2-5% by weight, glass fiber and/or carbon fiber! ! It can be seen that in a blend of 5 to 20% by weight, it is possible to provide a material for molded articles having any electrical conductivity of 102 to 1QI OΩ·am and high strength.

Example 4 Conductive PTW [Large] obtained by heating Tijin PBT CL7000 [odd character ■; polybutylene terephthalate] and potassium titanate whiskers to 300°C and conductively coating the surface with a spray of an aqueous solution of stannic chloride. Ketjen Black EC-P [manufactured by Lion Axie], Ketjen Black EC-P [manufactured by Lion Axie] and 6II long carbon fibers were mixed into a biaxial 4-layer φ set at 240°C with the compounding composition shown in Table 4 below. Dolphin-fried PBT CL7000 melted using an extruder
The above-mentioned conductive PTW, Ketjenblack EC-P and carbon fiber were mixed into the mixture and extrusion granulated. Thereafter, injection molding was performed under the following conditions to create a test piece for measuring physical properties.

Cylinder temperature = 245°C Injection pressure: 1000 kg/crs2 Injection time: 20 seconds Mold temperature: 100°C Next, the electrical properties and mechanical strength of the obtained test piece were measured. The results are shown in Table 4 below.

(Leaving space below) Table 4 Electrical properties and mechanical strength (effects of the invention) According to the present invention, the mechanical strength of the molded product is high, the dimensional accuracy is excellent, and the molded product can be formed anywhere from the insulating region to the conductive region. It is possible to easily obtain a resin composition that can reproduce the conductivity of .

In particular, the conductive thermoplastic resin composition of the present invention includes an antistatic material with a volume resistivity of 1014 to 1QI QΩ·cll, a semiconductive material with a volume resistivity of 1014 to 104Ω11, and a semiconductive material with a volume resistivity of 1014 to 104Ω
Because we can provide a conductive molding material of ~100Ω・C11.

Packaging of electronic parts, storage materials, copiers, printers, etc.
We provide resin materials suitable for molding A-class equipment mechanical parts, housings, etc.

Claims (1)

[Claims] (1) [a] 10-30% by weight of conductive potassium titanate fibers, [b] 0.3-5% by weight of conductive carbon black, [c] 5-30% by weight of glass fibers and/or or carbon fiber, a conductive thermoplastic resin composition having stable conductivity or semiconductivity and excellent strength.