JPH0737570B2 - Antistatic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a polyamideimide or polyetherimide antistatic resin composition.

<Prior Art> In recent years, an injection moldable polyamide or polyetherimide resin has been highly useful as an injection molding material for machine parts and the like because of its excellent heat resistance, mechanical strength and sliding characteristics.

On the other hand, as a conductive resin composition, a thermoplastic resin or a thermosetting resin, a conventional carbon black, an ordinary graphite and a non-conductive filler are mixed and kneadable, and a moldable resin composition is disclosed in JP-A-59-96142. Known from the gazette.

<Problems to be Solved by the Invention> When the technique described in JP-A-59-96142 is applied to a polyamide-imide or polyether-imide resin, the antistatic property is certainly obtained.

However, these resins, which originally have a very high melt viscosity and have a problem in injection moldability, have poorer injection moldability due to the application of such a technique, that is, antistatic treatment, and impaired dimensional stability due to unreasonable molding, Further, it has a defect that the mechanical strength is significantly impaired.

Therefore, as a result of earnestly studying as a subject to provide a resin composition having antistatic properties and simultaneously having a higher level of injection molding fluidity, dimensional stability and mechanical strength than conventional ones, a specific Carbon black, specific graphite,
That is, the inventors have found that the problem can be achieved by using a relatively small amount of lead-like graphite, and have reached the present invention.

<Means for Solving Problems> The object of the present invention is (a) 35 to 90% by weight of an injection-moldable resin composed of one or a mixture of two or more selected from polyamideimide and polyetherimide, (b) DBP oil absorption is 400ml / 100g or more, and the total amount of nickel and vanadium is 200ppm or less, conductive carbon black 0.5 to 3.0% by weight, (c) natural scaly graphite 2 to 18% by weight, (d) calcium, magnesium, 5 to 40% by weight of inorganic filler composed of one or a mixture of barium carbonate, sulfate, phosphate, silicate or talc and mica
And the total amount of components (b) and (c) is 4
It has been achieved by an antistatic, heat-resistant resin composition characterized by being up to 20% by weight.

The injection-moldable resin targeted by the present invention is one kind or a mixture of two or more kinds selected from heat-resistant resins containing one of the following two chemical structural formulas as a main component.

(1) Polyamide imide However, R represents a functional group selected from the following groups (a) to (f).

(2) Polyetherimide Note that n and m in the expressions (1) and (2) represent integers of 10 to 1000.

The blending amount of these resins is required to be 35% by weight or more in the resin composition in order to maintain molding fluidity and mechanical strength.
On the other hand, the upper limit of the compounding amount of the resin is 90% by weight in order to impart antistatic properties and dimensional stability by the other components of the present invention.

Next, the conductive carbon black used in the present invention is DBP.
Oil absorption is 400ml / 100g or more, and the total amount of nickel and vanadium is 200ppm or less.

The total amount of nickel and vanadium in the commonly used conductive carbon black is usually over 1000 ppm, but in the present invention, 200 ppm or less of the conductive carbon black may be used. It is important that the vanadium content is 80 ppm or less and the nickel content is 40 ppm or less.

If this total amount exceeds 200 ppm, not only the dispersibility of the carbon black decreases, but also the mechanical strength of the composition decreases, and the antistatic effect also decreases significantly.

In addition, the surface area of the conductive carbon black is also an important basic condition, and it is required to be 400 ml / 100 g or more in terms of DBP oil absorption. The DBP oil absorption referred to herein means the oil absorption measured according to the method specified in ASTM-D2414-79. If the DBP oil absorption of this carbon black is less than 400 ml / 100 g, a large amount of carbon black must be added to obtain a composition with sufficient antistatic properties, and the moldability and mechanical properties of the final composition are increased accordingly. It is not preferable because the strength is impaired. Regarding the conductive carbon black to which the present invention is applied, the upper limit of the DBP oil absorption amount is not particularly limited, but usually 750 ml / 100 g or less is preferably used for the convenience of production.

The amount of the carbon black added is required to be in the range of 0.5 to 3.0% by weight, preferably 0.7 to 2.5% by weight.

When the amount of the conductive carbon black added is less than 0.5% by weight, it is difficult to impart the antistatic property within a practical range even when used in combination with the specific graphite of the present invention, which is not preferable. On the other hand, when it is more than 3.0% by weight, it becomes difficult to maintain sufficient molding fluidity and mechanical strength of the composition, which is not preferable.

Next, the graphite used in the present invention needs to be natural scaly graphite. Generally, graphite as an industrial material is roughly classified into artificial graphite obtained by graphitizing coke, tar, pitch, etc. at high temperature and natural graphite. Furthermore, natural graphite is classified into scaly graphite and soil graphite depending on the place of origin. The present inventors have found that specific graphite, which is natural scaly graphite, is particularly excellent for the following reasons.

(1) It provides a higher antistatic effect than artificial graphite and earth-like graphite.

(2) Since the effect of increasing the dispersion of the conductive carbon black applied to the present invention is the highest, the deterioration of moldability and mechanical strength due to the addition of carbon black is remarkably reduced.

In the present invention, the particle size of natural scaly graphite is not particularly limited, but those having an average particle size of 0.8 to 12 μm by a spectroscopic measurement method are relatively preferable.

Further, the addition concentration of the graphite needs to be in the range of 2 to 18% by weight. If it is less than 2% by weight, it is difficult to sufficiently enhance the dispersibility of the conductive carbon black, as well as the antistatic effect of graphite itself.

On the other hand, if it exceeds 18% by weight, the conductive carbon black will be 0.
Even if it is less than 5% by weight, the graphite itself gives a sufficiently high antistatic property, but it is not preferable because it increases the influence of orientation in injection molding and reduces the dimensional stability of the molded product. This influence appears, for example, in that the linear expansion coefficient of the molded product has a large difference between the flow direction of the resin composition and the direction perpendicular to the flow, and impairs the practical value of a precision molded product requiring high dimensional accuracy.

Further, the total amount of the conductive carbon black and the natural scaly graphite, which is the object of the present invention, needs to be in the range of 4 to 20% by weight. In the case where the total amount is less than 4% by weight, if the proportion of carbon black is small, the antistatic property is insufficient, and if the proportion of carbon black is large, the antistatic property is sufficient, but the graphite Since it is too small, the dispersibility of the conductive carbon black is poor and the injection moldability and mechanical strength are significantly impaired. On the other hand, if the total amount exceeds 20% by weight, the adverse effect of the orientation in injection molding increases and the mechanical strength level of the molded product significantly decreases, which is not preferable.

Next, as the fourth component of the resin composition of the present invention, an inorganic material composed of one or a mixture of two or more kinds selected from carbonate, sulfate, phosphate, silicate or talc and mica of calcium, magnesium and barium. Requires 5-40% by weight of filler. In the resin composition of the present invention, such an inorganic filler is necessary in order to give injection molded articles high dimensional stability. Further, such an inorganic filler has a function of enhancing the antistatic effect of the conductive carbon black and graphite,
It is also effective in enhancing rigidity and heat resistance. The addition amount of these inorganic fillers needs to be appropriately determined according to the required performance, but generally the range of 5 to 40% by weight is required. If it is less than 5% by weight, the dimensional stabilizing effect is poor, and if it exceeds 40% by weight, it becomes difficult to maintain the mechanical strength.

The particle size of the inorganic filler is not particularly limited, but in most cases, an average particle size of 50 μm or less is suitable.

Furthermore, as a matter of course, in the resin composition of the present invention, in addition to the above four components, other appropriate fillers and heat stabilizers are added to strengthen, suppress thermal expansion, increase slidability, improve heat resistance, Effects such as increased dimensional stabilization can be provided. The filler that can be additionally added is not particularly limited, but a fiber material having excellent heat resistance and solid fine powder are effective. As the fiber material, glass fiber, carbon fiber, steel fiber, brass fiber, potassium titanate whisker and the like having excellent heat resistance and durability are used. As the solid fine powder, colloidal silica, quartz powder, tungsten disulfide, molybdenum disulfide, boron nitride, ferrite powder, magnetite powder and the like are used. Among these fillers, carbon fiber, steel fiber, and brass fiber have an effect of reducing conductive carbon black and graphite within the addition range of the present invention from the viewpoint of antistatic property.

Further, with respect to the resin composition of the present invention, if it is a small amount, known thermoplastic polymers such as polysulfone, polyether sulfone, polyallyl sulfone, polyarylate, polyether ether ketone, and injection moldable polyimide. You may use together.

The resin composition of the present invention is obtained by mixing and kneading the component raw materials described above. For kneading, a conventional method, for example, batch kneading with a Banbury mixer or the like, followed by pulverization, or dry blending with a Henschel mixer, continuous kneading and extrusion with an extruder to form pellets, or pulverization A method of forming irregularly shaped particles can be adopted.

<Example> Next, an example will be described in detail.

The methods for measuring the isotropic volume resistivity and the coefficient of linear expansion described in Examples and Comparative Examples are as follows.

(1) Volume resistivity Using a SM-10E type Ultramegomb meter manufactured by Toa Electronics Co., Ltd., a disc 40 mm in diameter and 3 mm in thickness was injection-molded, surface load 5 kg / cm ² , applied voltage 1000 V, Atmosphere 23
Measure at 60 ℃ and 60% RH.

(2) Isotropic linear expansion coefficient A rectangular prism with a size of 30 mm square and a thickness of 3 mm, which is injection-molded with a film gate mold, has a cross section of 3 mm square and a length of 16 mm from the central part, and is perpendicular to the resin flow direction. Cut out in the direction. (Create one test piece from one flat plate) The linear expansion coefficient of this test piece in the longitudinal direction is measured by Rigaku Denki's thermomechanical analyzer (TM
Using A), temperature rise 1 ° K / min, measurement temperature range 30-80
Measure under the condition of ° C. The isotropy of the linear expansion coefficient is indicated by the difference between the linear expansion coefficient of the resin in the flow direction and the linear expansion coefficient in the direction perpendicular to the flow. The smaller the difference, the higher the dimensional stability.

The compositions of Examples 1 to 7 and Comparative Examples 1 to 8 are shown in Table-1, the physical property measurement results are shown in Table-2, Examples 8 to 19 and Comparative Examples 9 to.
The composition of 14 is shown in Table 3, and the physical property measurement results are shown in Table 4.

Example 1 Polyamideimide (PAI) powder represented by the following chemical structural formula 3.5kg and DBP oil absorption 480ml / 100g, nickel content 15ppm, vanadium content 50ppm conductive carbon black (Lion Akzo, EC-DJ600) 0.15kg and natural scaly graphite (CP, Nippon Graphite Industry) 1.5kg and calcium carbonate Powder (KSS-100
0, made by Konpei Mining Co., Ltd.) (2.4 kg) and glass fiber (Chioppdo Strand, TN-101, made by Nippon Glass Electric Co., Ltd.) 2.45 kg are uniformly mixed for 10 minutes with a drum tumbler of 50, and then 45 m / mφ
Using a twin-screw extruder (PCM-45, manufactured by Ikegai Tekko Co., Ltd.), the mixture was kneaded and extruded at a cylinder temperature of 335 ° C. and a screw rotation speed of 80 rpm, and made into pellets with a hot cut. The obtained pellets were subjected to a volume resistivity test piece (diameter) under the conditions of a cylinder temperature of 328 ° C, a mold temperature of 160 ° C, and an injection pressure of 1000 kg / cm ³ using a 75TON injection molding machine (Cycap, manufactured by Sumitomo Heavy Industries).
40mm, 3mm thick disc) No. 1 dumbbell (ASTM-D-63
8), Bending elastic modulus measurement test piece (130mm × 12.4mm × 3mm),
A linear expansion coefficient measurement test piece (30 mm × 30 mm × 3 mm, square plate) was molded, and volume specific resistance (Rv) as antistatic performance, tensile strength (TS) as strength, and bending elastic modulus (FM) as
Isotropic (ELE) such as linear expansion was measured as a measure of dimensional stability. The composition obtained as shown in Table 1 has practically good molding fluidity, Rv shows an average value of 8 × 10 ⁴ Ω · cm, and a variation range (n = 50) 7 × 10 ^{4 to} 9 × 10 ⁴ Ω ・ cm is sufficiently uniform for practical use, TS800 kg / cm ² , FM22 × 10 ⁴ kg / c
It showed m ² and ELE of 0.02 × 10 ^-5 / ° C, and was excellent in antistatic property, strength and dimensional stability as a molding material.

Example 2 A composition was obtained by changing the PAI content, the calcium carbonate content and the glass fiber content as shown in Table 1 in Example 1, and the composition was tested in the same manner as in Example 1. The results are shown in Table-2.
As shown, it was a sufficient molding material.

Example 3 A test was performed in the same manner as in Example 1 except that PAI was changed to 9.0 kg, graphite was changed to 0.35 kg, calcium carbonate was changed to 0.5 kg, and glass fiber was not added in Example 1. As shown in Table 1, the molding fluidity was good, and the antistatic property, strength, and dimensional stability were sufficient as molding materials.

Comparative Example 1 In Example 1, the PAI content was 3.0 kg and calcium carbonate was 2.
When changing to 7kg and 2.65kg of glass fiber, blend the mixture mixed in a tumbler and set the cylinder temperature of the twin-screw extruder to 345 ° C.
Even though it was finally set into a pellet shape with a hot cut, it was impossible to mold the test piece due to poor fluidity in injection molding.

Comparative Example 2 The composition when the PAI compounding amount in Example 1 was changed to 9.2 kg, conductive carbon black 0.10 kg, graphite 0.20 kg, calcium carbonate 0.5 kg, and no glass fiber was added is shown in Table 1.
As shown in Fig. 2, the range of Rv variation is large and the ELE is large, so the dimensional stability is poor and the molding material is of poor practical value.

Example 4 7.0 kg of PAI powder having the following chemical structural formula and DBP oil absorption of 420 ml / 100
g, nickel content 40ppm, vanadium content 140ppm, conductive carbon black 0.2kg, natural scaly graphite (CSP, manufactured by Nippon Graphite Industry Co., Ltd.) 0.8kg, and calcium sulfate dihydrate (manufactured by Hanai Chemical Co., Ltd.) fine powder 2.0kg. After uniformly mixing with a 50 drum tumbler for 10 minutes, the mixture was kneaded and extruded under the same conditions as in Example 1, molded, and evaluated.

The results are shown in Table 2, and the obtained composition was excellent in antistatic property, high in strength level and dimensional stability and of high practical value.

Comparative Example 3 In the same manner as in Example 4, except that the DBP oil absorption of the conductive carbon black was changed to 350 ml / 100 g, each test piece was molded and measured. As shown in Table 2, the antistatic property was tentatively recognized, but the variation was large, which was unsatisfactory in practical use.

Comparative Example 4 A test was performed in the same manner as in Example 4 except that the total amount of nickel and vanadium in the conductive carbon black was changed to 3000 ppm. The results are shown in Table-2, and because the dispersibility of the carbon black is poor, the molding fluidity is poor.
The volume resistivity had large variations and the dimensional stability was low.

Example 5 In Example 1, the PAI content was 8.0 kg, the amount of conductive carbon black added was 0.05 kg, graphite was 1.0 kg, and calcium carbonate was used.
A test was performed in the same manner as in Example 1 except that 2.4 kg was replaced with 0.95 kg of talc (MST, manufactured by Takehara Chemical Industry Co., Ltd.) and glass fiber was not added. The evaluation results are shown in Table-2. Although the antistatic property was slightly low, it was in a practical range because the variation was small, and the strength level and dimensional stability were sufficient.

Example 6 A test was conducted in the same manner as in Example 5 except that the conductive carbon black was changed to 0.30 kg and the talc content was changed to 0.70 kg. As shown in Table 2, the obtained composition was excellent in antistatic property and dimensional stability, and had practically no problem in molding fluidity and strength.

Comparative Example 6 In Example 5, the amount of conductive carbon black added was 0.35.
A test was conducted in the same manner as in Example 5 except that kg, graphite was 1.35 kg, and talc content was changed to 6 kg. As a result, the molding fluidity was poor and the strength was remarkably low.

Example 7 In Example 1, the PAI content was 8.0 kg, the conductive carbon black content was 0.10 kg, the graphite content was 1.0 kg, and the calcium carbonate content was 2.4 kg using mica (Szolite Mica 325-HK,
Marietta resource internal (manufactured by International) 0.9kg,
A test was conducted in the same manner as in Example 1 except that the glass fiber compounding amount was changed to be no addition. The results are shown in Table 2, and the molding, antistatic property, strength, and dimensional stability were satisfactory as molding materials.

Comparative Examples 7 and 8 Also in Example 7, the type of graphite is natural earth (AP, manufactured by Nippon Graphite Industry) or artificial graphite powder (SE manufactured by Nippon Carbon).
G-RH round bar crushed product) was used, and the same test as in Example 7 was carried out. The results are shown in Table 2. All of the compositions had low antistatic properties and were insufficient in dimensional stability as compositions for precision molding in view of the isotropic linear expansion coefficient.

Example 8 In Example 5, the PAI content was 7.5 kg, the conductive carbon black content was 0.25 kg, the graphite content was 0.20 kg, and talc was added.
0.95 kg of calcium phosphate (third) (manufactured by Hanai Chemical)
Was tested in the same manner as in Example 5 except that the amount of the fine powder was changed to 2.05 kg. As shown in Table 4, the obtained composition was excellent in antistatic property and dimensional stability, and had molding fluidity and tensile strength that could be practically used.

Example 9 In Example 5, PAI content was 7.5 kg, conductive carbon black content was 0.20 kg, graphite content was 1.8 kg, and talc 0.95 kg was magnesium carbonate (basic) (manufactured by Hanai Chemical Co., Ltd.). The same test as in Example 5 was carried out except that the powder was changed to 0.50 kg. The obtained composition is as shown in Table-4.
It was an excellent molding material with excellent balance of physical properties.

Comparative Example 9 The procedure of Example 8 was repeated, except that the amount of graphite was changed to 0.15 kg and the amount of calcium phosphate (third) to be changed to 2.1 kg. As a result, as shown in Table 4, the dispersibility of the conductive carbon black was poor, resulting in a large variation in the volume resistivity value and insufficient dimensional stability.

Comparative Example 10 The amount of conductive carbon black added in Example 9 was 0.10.
kg and the amount of graphite added were changed to 1.9 kg and the same procedure as in Example 9 was carried out. Although the composition obtained had good fluidity, it was insufficient as a molding material because of its low isotropic linear expansion coefficient.

Example 10 In Example 8, 0.15 kg of conductive carbon black was used.
, Graphite addition amount to 0.25kg, calcium phosphate powder 2.05
The test was performed in the same manner as in the example, except that kg was changed to 2.10 kg of barium carbonate powder (manufactured by Hanai Chemical Co., Ltd.). The obtained composition was satisfactory as a molding material as shown in Table 4.

Example 11 In Example 10, the PAI blending amount was 6.5 kg, the conductive carbon black addition amount (B) was 0.20 kg, and the graphite addition amount (C) was
The test was performed in the same manner as in Example 10 except that 1.8 kg was changed to 2.10 kg of barium carbonate powder and 1.50 kg of anhydrous magnesium sulfate (Hanai Chemical Chemicals) was used. As shown in Table 4, the obtained composition was excellent in antistatic property and had no problem in strength level and dimensional stability.

Comparative Example 11 In Example 10, the conductive carbon black addition amount (B) was 0.050 kg, and the graphite addition amount (C) was 0.20 kg.
((B) + (C) 0.25 kg), 2.25 barium carbonate powder
The test was performed in the same manner as in Example 10 except that the weight was changed to kg.
The obtained composition had an insufficient antistatic property as shown in Table 4.

Comparative Example 12 The same as Example 11 except that the conductive carbon black addition amount (B) was changed to 0.30 kg ((B) + (C) 2.1 kg) and the magnesium sulfate powder was changed to 1.40 kg. Carried out. As shown in Table 4, the obtained composition was excellent in antistatic property, but also low in strength level and dimensional stability, and was insufficient as a molding material.

Examples 12 to 16 In Example 5, 0.15 kg of conductive carbon black,
Graphite addition amount to 0.65 kg, as a fourth component, barium sulfate powder (Example 12), magnesium phosphate (first) powder (Example 13), barium phosphate (meta) manufactured by Hanai Chemical Co., Ltd.
Powder (Example 14), calcium silicate powder (Example 1)
5) and magnesium silicate powder (Example 16) were changed to 1.20 kg, and the same test as in Example 5 was carried out. As the results are shown in Table 4, all of the obtained compositions had a good physical property balance and were sufficient as injection molding materials.

Example 17 In Example 10, the PAI blending amount to 8.7 kg, the graphite addition amount
0.65 kg, barium carbonate 2.1 kg, calcium carbonate powder 0.5
The same procedure as in Example 10 was carried out except that the amount was changed to 0 kg. The obtained composition had an excellent physical property balance as shown in Table 4 and was satisfactory as a molding material.

Comparative Example 13 In Example 17, the PAI was 8.9 kg, the calcium carbonate addition amount was 0.30 kg, respectively, when tested in the same manner as in Example 17 except that the dimensional stability was as shown in Table 4. It was bad and was insufficient as a molding material.

Example 18 Example 17 was carried out in the same manner as in Example 17, except that the PAI blending amount was changed to 5.2 kg and the calcium carbonate addition amount was changed to 4.0 kg. As shown in Table 4, the obtained composition had sufficient antistatic properties and strength, and was particularly excellent in dimensional stability, and was thus preferable as a molding material.

Comparative Example 14 In Example 18, the PAI blending amount was 4.7 kg, the calcium carbonate addition amount was 4.5 kg, each was tested in the same manner as in Example 18 except that the strength level was changed as shown in Table 4. It was an insufficient molding material.

Example 19 5.5 kg of polyetherimide powder having the following chemical structural formula
And DBP oil absorption 480ml / 100g, nickel content 15ppm, Panadium content 50ppm conductive carbon black (Lion Akzo, EC-DJ600) 0.20kg and natural scaly graphite (CSP, Nippon Graphite Industry) 1.0kg and talc powder (MST , Manufactured by Takehara Chemical) 0.8kg
And 2.5 kg of glass fiber (Chopped Strand, TN-102, manufactured by Nippon Glass Electric Co., Ltd.) with 10 drum drum tumblers for 10
After uniformly mixing for 30 minutes, 30m / mφ twin-screw extruder (PCM-30,
(Made by Ikegai Tekko Co., Ltd.), the temperature of the cylinder was set at 350 ° C., the kneading and extruding was performed at a screw rotation speed of 70 rpm, and pellets were formed by a hot cut. Cylinder temperature of the obtained pellets with a 75TON injection molding machine (Cycap, Sumitomo Heavy Industries)
The same test piece as in Example 1 was molded and measured under the conditions of 365 ° C., mold temperature 95 ° C., injection pressure 1050 kg / cm ³ .

The compositions obtained as shown in Table 4 were excellent in molding fluidity, antistatic property, strength and dimensional stability, all of which were maintained at sufficient levels, and were excellent as molding materials. .

<Effects of the Invention> According to the present invention, it is possible to obtain a resin composition having a high degree of antistatic property and excellent dimensional stability while suppressing a decrease in mechanical strength of polyamideimide and polyetherimide. Unlike the case of the heat-resistant and antistatic resin composition, the composition can be provided as an excellent material for precision injection molding. Therefore, the resin composition of the present invention can be applied to various uses. For example, as a molding material for various mechanical parts that require antistatic properties in sliding parts such as optical / magnetic applied equipment in VTRs, video disks, compact disks, etc., and OA equipment and other general industrial equipment. For special applications, it can be used in many fields such as molding materials for paper separation tabs of copying machines.

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Claims (1)

[Claims] 1. An injection-moldable resin consisting of (a) one or a mixture of two or more selected from polyamideimide and polyetherimide 35-90% by weight (b) DBP oil absorption of 400 ml / 100 g or more, and Conductive carbon black having a total amount of nickel and vanadium of 200 ppm or less 0.5 to 3.0% by weight (c) Natural scaly graphite 2 to 18% by weight (d) Calcium, magnesium, barium carbonate,
5 to 40% by weight of an inorganic filler consisting of one or a mixture of two or more selected from sulfate, phosphate, silicate or talc, mica, and the total amount of components (b) and (c) 4
An antistatic resin composition, characterized in that the content is up to 20% by weight.