JP6837180B2 - Composite materials for hot press molded products and hot press molded products - Google Patents

Description

The present invention relates to a polyarylene sulfide resin composite material for a hot press molded product and a hot press molded product.

Since the polyarylene sulfide resin has high mechanical strength and is excellent in heat resistance, chemical resistance and dimensional stability, molded products containing the polyarylene sulfide resin are applied to various uses. When a filler that imparts a function to a molded product is mixed with a polyarylene sulfide resin to produce a molded product, it is important to control the dispersion of the filler in the molded product in order to efficiently exhibit the desired function. Be seen. Conventionally, as a method for obtaining a molded product containing a polyarylene sulfide resin, a method in which pellets of a composite material containing a polyarylene sulfide resin and a filler are once produced by melt extrusion and the pellets are molded by injection molding is widely used. It is used. Patent Document 1 describes that pellets of a composite material containing a polyarylene sulfide resin and conductive carbon black are produced by melt extrusion, and the pellets are injection-molded to obtain a molded product. However, such conventional methods may result in insufficient dispersibility of the filler.
Hot press molding is a molding method in which resin powder is heat press molded at a temperature at which the resin melts, and has a feature that the anisotropy of the molded product can be controlled as compared with injection molding in which the resin powder is melted at a high temperature such that the resin flows. is there. Further, since the resin can be mixed with various fillers in a powder state, a molded product having excellent dispersibility of the filler can be easily produced.

International Publication No. 2002/03670

An object of the present invention is to provide a polyarylene sulfide resin composite material capable of producing a hot press molded product having excellent heat resistance and excellent dispersibility of a filler, and a hot press molded product using the same. And.

The present invention relates to the following.
[1] The polyarylene sulfide resin powder containing a polyarylene sulfide resin powder and a filler, the average particle size of the polyarylene sulfide resin powder is 5 μm or more and 100 μm or less, and the melting point Tm1 measured by a differential scanning calorimeter is 250 ° C. A composite material for a hot press molded product, which has a temperature of 300 ° C. or higher and an average circularity of 0.70 or higher and 1.00 or lower measured by a dynamic image analysis method.
[2] The composite material according to [1], wherein the amount of water measured by the Karl Fischer titer of the polyarylene sulfide resin powder is 0.1 ppm or more and 750 ppm or less.
[3] The melt viscosity measured at a cylinder temperature 30 ° C. higher than the melting point Tm1 measured by a differential scanning calorimeter of polyarylene sulfide resin powder and a shear rate of 1216 sec ^-1 is 10 Pa · s or more and 1000 Pa · s or less. , [1] or [2].
[4] Described in any one of [1] to [3], wherein the ratio of the maximum particle size to the average particle size (maximum particle size / average particle size) of the polyarylene sulfide resin powder is 6.5 or less. Composite material.
[5] The composite material according to any one of [1] to [4], wherein the filler contains a conductive filler.
[6] Described in any one of [1] to [5], wherein the filler contains at least one selected from the group consisting of carbon fiber, milled carbon fiber, carbon nanofiber, carbon nanotube, carbon black and graphite. Composite material.
[7] A hot press molded product using the composite material according to any one of [1] to [6].
[8] The hot press molded product according to [7], which has a plate shape with a thickness of less than 5 mm.

According to the present invention, there is provided a polyarylene sulfide resin composite material capable of producing a hot press molded product having excellent heat resistance and excellent dispersibility of a filler, and a hot press molded product using the same. Can be done.

Hereinafter, one embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications as long as the effects of the present invention are not impaired.

[Composite material for hot press molded products]
The composite material for a hot press molded product (hereinafter, also simply referred to as “composite material”) according to the present embodiment includes a polyarylene sulfide resin powder and a filler.

(Polyarylene sulfide resin powder)
The polyarylene sulfide resin powder (hereinafter, also referred to as “resin powder”) is composed of polyarylene sulfide resin fine particles. In the present specification, the term "fine particles" refers to particles having an average particle size of about 0.1 μm to 1000 μm, and the “average particle size” is a volume measured by a laser diffraction / scattering type particle size distribution measurement method. It means the standard arithmetic average particle size. The average particle size can be measured using a laser diffraction / scattering type particle size distribution measuring device (for example, a laser diffraction / scattering type particle size distribution measuring device LA-920 manufactured by HORIBA, Ltd.).

The polyarylene sulfide resin is a resin having a repeating unit represented by the following general formula (I).
-(Ar-S)-... (I)
(However, Ar indicates an arylene group.)

The arylene group is not particularly limited, but for example, a p-phenylene group, an m-phenylene group, an o-phenylene group, a substituted phenylene group, a p, p'-diphenylene sulphon group, a p, p'-biphenylene group, p, Examples thereof include a p'-diphenylene ether group, a p, p'-diphenylene carbonyl group, and a naphthalene group. The polyarylene sulfide resin can be a copolymer containing different repeating units depending on the application, in addition to a homopolymer using the same repeating unit among the repeating units represented by the above general formula (I).

As the homopolymer, one having a p-phenylene group as an arylene group and having a p-phenylene sulfide group as a repeating unit is preferable. This is because homopolymers having a p-phenylene sulfide group as a repeating unit have extremely high heat resistance, and exhibit high strength, high rigidity, and high dimensional stability in a wide temperature range. By using such a homopolymer, a molded product having very excellent physical properties can be obtained.

As the copolymer, a combination of two or more different arylene sulfide groups among the above-mentioned arylene sulfide groups containing an arylene group can be used. Among these, a combination containing a p-phenylene sulfide group and an m-phenylene sulfide group is preferable from the viewpoint of obtaining a molded product having high physical properties such as heat resistance, moldability and mechanical properties. A polymer containing 70 mol% or more of p-phenylene sulfide group is more preferable, and a polymer containing 80 mol% or more is further preferable. The polyarylene sulfide resin having a phenylene sulfide group is a polyphenylene sulfide resin (PPS resin).

The polyarylene sulfide resin is generally known to have a molecular structure that is substantially linear and does not have a branched or crosslinked structure, or a structure that has a branched or crosslinked structure, depending on the production method. Is valid for any of these types.

The method for producing the polyarylene sulfide resin is not particularly limited, and the polyarylene sulfide resin can be produced by a conventionally known production method. For example, it can be produced by synthesizing a low molecular weight polyarylene sulfide resin and then polymerizing it at a high temperature in the presence of a known polymerization aid to increase the molecular weight. The polyarylene resin thus obtained can be used as it is as a polyarylene resin powder as described later, or can be pulverized by various methods described later into fine particles and used as a polyarylene resin powder.

The average particle size of the polyarylene sulfide resin powder is 5 μm or more and 100 μm or less, preferably 10 μm or more and 80 μm or less, and more preferably 20 μm or more and 50 μm or less. By setting the average particle size to 5 μm or more and 100 μm or less, uniform mixing and uniform dispersion with the filler becomes possible in the polyarylene sulfide resin composite material for hot press molded products. The method for measuring the "average particle size" is as described above.

The ratio of the maximum particle size to the average particle size (maximum particle size / average particle size) of the polyarylene sulfide resin powder is preferably 6.5 or less, and more preferably 5.5 or less. The lower limit is not particularly limited and may be 1 or more. The "maximum particle size" means the maximum value among the values measured by (laser diffraction / scattering type particle size distribution measurement method). By setting the ratio of the maximum particle size to the average particle size (maximum particle size / average particle size) to 6.5 or less, it is possible to suppress variations in the physical properties of the hot press molded product.

The production of the polyarylene sulfide resin powder having the above average particle size is not particularly limited, and the polyarylene sulfide resin obtained by the method for producing the polyarylene sulfide resin can be used as it is as the resin powder, or the above. Polyarylene sulfide resin molded into pellets, fibers, film, etc. was crushed by dry crushing, wet crushing, and freezing crushing using a jet mill, bead mill, hammer mill, ball mill, cutter mill, stone mill type grinder, etc. You can also use the one. In addition, a method of dissolving the polyarylene sulfide resin in a solvent and then spray-drying, a poor solvent precipitation method in which an emulsion is formed in the solvent and then contacted with a poor solvent, and an organic solvent are used after the emulsion is formed in the solvent. An in-liquid drying method or the like for drying and removing can also be used. It is also possible to use a method of mixing the polyarylene sulfide resin and the thermoplastic resin, and then dissolving and removing the thermoplastic resin with a solvent to obtain a polyarylene sulfide resin powder having the above average particle size.

The melting point Tm1 measured by the differential scanning calorimetry of the polyarylene sulfide resin powder is 250 ° C. or higher and 300 ° C. or lower, preferably 255 ° C. or higher and 300 ° C. or lower, and more preferably 260 ° C. or higher and 300 ° C. or lower. .. By setting the melting point Tm1 to 250 ° C. or higher and 300 ° C. or lower, the heat resistance of the hot press molded product can be enhanced, and when the above average particle size and the average circularity described later are satisfied, the dispersibility of the filler is excellent. It can be made into a hot press molded product.
The melting point Tm1 is the temperature of the peak top at the endothermic peak of 1st RUN observed when heating (1st RUN) from room temperature at a heating rate of 10 ° C./min by a method based on JIS K-7121 (1999). To do.

The polyarylene resin fine particles constituting the polyarylene sulfide resin powder have a predetermined circularity. That is, the polyarylene sulfide resin powder has an average circularity of 0.70 to 1.00, more preferably 0.80 to 1.00, as measured by the dynamic image analysis method. By setting the average circularity within this range, it is possible to uniformly mix and uniformly disperse the polyarylene sulfide resin composite material for hot press moldings with the filler.
The average circularity is calculated from the following formula (II) from the area A and the peripheral length P for 4500 fine particles in the polyarylene sulfide resin powder using a dynamic image analysis method / particle state analyzer. Calculate and use as the average value.
Circularity = (4 × π × A) / P ² ... (II)

The polyarylene sulfide resin powder preferably has a water content of 0.1 ppm or more and 750 ppm or less, and more preferably 1 ppm or more and 500 ppm or less, as measured by a Karl Fischer titer. By setting the water content within this range, the mixability and dispersibility with the filler can be satisfactorily controlled during the production of the polyarylene sulfide resin composite material for hot press molding, and in the molten state during hot press molding. It is possible to suppress the generation of gas and the generation of voids (pores).

The polyarylene sulfide resin powder has a cylinder temperature 30 ° C. higher than the melting point Tm1 measured by a differential scanning calorimeter ^{and a melt viscosity measured at a shear rate of 1216 sec -1} which is 10 Pa · s or more and 1000 Pa · s or less. It is preferably 20 to 800 Pa · s, more preferably 50 Pa · s or more, and 800 Pa · s or less. By setting the melt viscosity of the polyarylene sulfide resin powder within the above range, it is possible to improve the processability at the time of hot press molding, the appearance of the molded product, and the mechanical properties. The melt viscosity can be adjusted by adjusting the monomer charging ratio at the time of polymerization of the polyarylene sulfide resin, controlling the polymerization time, blending polyarylene sulfide resins having different melt viscosities, and the like. By setting the melt viscosity to 10 Pa · s or more, the weight average molecular weight can be set to 15,000 or more.

(filler)
Examples of the filler include various fibrous, powdery, plate-like inorganic and organic fillers. Fibrous fillers include glass fibers, milled glass fibers, carbon fibers, milled carbon fibers, carbon nanofibers, carbon nanotubes, asbestos fibers, silica fibers, silica-alumina fibers, alumina fibers, zirconia fibers, boron nitride fibers, and nitrided fibers. Silicon fiber, boron fiber, potassium titanate fiber, silicate fiber such as wollastonite, magnesium sulfate fiber, aluminum borate fiber, and inorganic material such as metal fibrous material such as stainless steel, aluminum, titanium, copper and brass. Fibrous substances can be mentioned.
A preferred fibrous filler is a conductive filler, and a particularly preferred fibrous filler is one or more selected from carbon fibers, milled carbon fibers, carbon nanofibers, and carbon nanotubes. In addition, high melting point organic fibrous substances such as polyamide, fluororesin, polyester resin, and acrylic resin can also be used.
The average fiber length of the fibrous filler is preferably 150 μm or less in terms of enhancing the dispersibility with the polyarylene sulfide resin powder. The average fiber length can be measured using, for example, the image measuring device LUZEXFS manufactured by Nicolet Co., Ltd.
Examples of the powder / granular filler include carbonates such as carbon black, graphite, silica, quartz powder, glass beads, glass balloons, glass powder, calcium carbonate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite. , Iron oxide, titanium oxide, zinc oxide, antimony trioxide, metal oxides such as alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, and other ferrites and carbides. Examples thereof include calcium, calcium nitride, boron nitride, and various metal powders. A preferred powder-granular filler is a conductive filler, and a particularly preferable powder-granular filler is one or more selected from carbon black and graphite.
Examples of the plate-shaped filler include mica, glass flakes, talc, and various metal foils.
The average particle size of the powder granular filler and the plate-shaped filler is preferably 500 nm or less or 400 nm or less in terms of enhancing the dispersibility with the polyarylene sulfide resin powder. The average particle size can be measured by the same method as the above-mentioned resin fine particles.
These inorganic and organic fillers can be used alone or in combination of two or more.

The content of the filler is preferably 10 to 400 parts by mass, and more preferably 15 to 350 parts by mass with respect to 100 parts by mass of the polyarylene sulfide resin. The content of the filler is preferably 9 to 80% by mass, more preferably 13 to 78% by mass in the composite material.

Further, in the composite material, as other components, additives such as antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, pigments, crystal nucleating agents, etc. do not impair the effects of the present invention, for example, composites. It may be blended in 0.01 to 3% by mass in the material.

The composite material includes crystalline thermoplastic resins such as polyoxymethylene resin, polybutylene terephthalate resin and liquid crystal resin, and amorphous thermoplastic resins such as polyether sulfone, polyetherimide, polycarbonate and cycloolefin copolymer. Other thermoplastic resins such as, for example, may be contained in the composite material in an amount of 20% by mass or less as long as the effects of the present invention are not impaired.

As a method for mixing various components for obtaining a composite material containing a polyarylene sulfide resin powder and a filler, and an additive which may be contained if necessary, a conventionally known method can be used, for example. A mixing method using shaking, a mixing method involving pulverization of a ball mill or the like, a mixing method using a stirring blade such as a Henschel mixer, or the like can be used.

[Hot press molded product]
The hot press molded product is a hot press molded product formed by using the composite material containing the polyarylene sulfide resin powder and the filler described above. In the above-mentioned composite material, the filler is uniformly mixed in the polyarylene sulfide resin powder and uniformly dispersed. As a result, the physical properties such as strength and heat resistance of the obtained hot press molded product are made uniform. It is possible to obtain a highly reliable molded product. Therefore, this hot press molded product includes automobile parts used at high temperatures (for example, in an environment where the temperature can reach 250 ° C. or higher), electrical / electronic parts mounted in the solder reflow process, fuel cell separators, plastic magnets, and the like. It can be preferably used as a composite material with a metal material, a composite material with a ceramic, or the like.

The hot press molded product can be obtained by press molding the above-mentioned composite material with a hot press molding machine at a temperature (for example, 250 ° C. to 400 ° C.) of the above melting point Tm1 or more of the polyarylene sulfide resin powder. .. The pressure at the time of molding is not particularly limited, and can be a pressure capable of molding to a desired thickness. The thickness of the molded product is appropriately selected according to the application and / or the required performance, and can be, for example, less than 5 mm.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the interpretation of the present invention is not limited by these Examples.

[Polyarylene sulfide resin]
The polyarylene sulfide resin used in Examples and Comparative Examples is as follows.
PPS1: Polyphenylene sulfide resin, "Fortron KPS" manufactured by Kureha Corporation, (melt viscosity: 30 Pa · s (shear rate: 1216 sec- ¹ , 310 ° C))
PPS2: Polyphenylene sulfide resin, "Fortron KPS" manufactured by Kureha Corporation, (melt viscosity: 130 Pa · s (shear rate: 1216 sec ^-1 , 310 ° C))

[Examples 1 and 2]
PPS1 was subjected to dry pulverization using an airflow jet mill (Seishin Enterprise Co., Ltd., vertical jet crusher SK Jet O Mill) to obtain polyarylene sulfide resin powder. The melting point Tm1, water content, melt viscosity, average particle size and maximum particle size, and average circularity of this resin powder were measured by the methods described below. The results are shown in Table 1.
After mixing the obtained polyarylene sulfide resin powder and conductive carbon black (manufactured by Mitsubishi Chemical Co., Ltd., # 3050B, average particle size 40 nm) at the content ratios shown in Table 1 with a Henschel mixer to form a composite material. 3 g is filled in an aluminum ring having a diameter of 40 mm and pressed using a hot press molding machine (“Mini Test Press-10” manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a temperature of 310 ° C. and a pressure of 5 MPa to heat. A press-molded product (a plate-shaped molded product having a diameter of 40 mm and a thickness of 2 mm) was manufactured. The surface properties of this hot press molded product and the dispersibility of the filler were evaluated by the methods described below. The results are shown in Table 1.

[Example 3]
A polyarylene sulfide resin powder was obtained in the same manner as in Example 1 except that PPS2 was used instead of PPS1. In the same manner as in Example 1, the melting point Tm1, water content, melt viscosity, average particle size and maximum particle size, and average circularity of the polyarylene sulfide resin powder were measured. The results are shown in Table 1.
Using the obtained polyarylene sulfide resin powder, a composite material was obtained in the same manner as in Example 1, and a hot press molded product was produced in the same manner as in Example 1. In the same manner as in Example 1, the surface properties of the hot press molded product and the dispersibility of the filler were evaluated. The results are shown in Table 1.

[Comparative Example 1]
Polyarylene sulfide resin fine particles were obtained in the same manner as in Example 1 except that PPS1 was freeze-crushed using a mesh mill type crusher (HA-2542, manufactured by Horai Co., Ltd.) to obtain polyarylene sulfide resin fine particles. It was. In the same manner as in Example 1, the melting point Tm1, water content, melt viscosity, average particle size and maximum particle size, and average circularity of the polyarylene sulfide resin powder were measured. The results are shown in Table 1.
Using the obtained polyarylene sulfide resin powder, a composite material was obtained in the same manner as in Example 1, and a hot press molded product was produced in the same manner as in Example 1. In the same manner as in Example 1, the surface properties of the hot press molded product and the dispersibility of the filler were evaluated. The results are shown in Table 1.

[Comparative Example 2]
PPS2 was used without pulverization to obtain a polyarylene sulfide resin powder. In the same manner as in Example 1, the melting point Tm1, water content, melt viscosity, average particle size and maximum particle size, and average circularity of the polyarylene sulfide resin powder were measured. The results are shown in Table 1.
Using the obtained polyarylene sulfide resin powder, a composite material was obtained in the same manner as in Example 1, and a hot press molded product was produced in the same manner as in Example 1. In the same manner as in Example 1, the surface properties of the hot press molded product and the dispersibility of the filler were evaluated. The results are shown in Table 1.

[Comparative Example 3]
PPS2 was used without pulverization to obtain a polyarylene sulfide resin powder. In the same manner as in Example 1, the melting point Tm1, water content, melt viscosity, average particle size and maximum particle size, and average circularity of the polyarylene sulfide resin powder were measured. The results are shown in Table 1.
Using the obtained polyarylene sulfide resin powder, a composite material was obtained in the same manner as in Example 1, and an attempt was made to produce a hot press molded product in the same manner as in Example 1. And the conductive carbon black were not sufficiently adhered to each other and could not be molded.

[Measurement]
(Melting point Tm1)
The temperature of the peak top at the endothermic peak observed when heating (1stRUN) from room temperature at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Corporation) is set as the melting point Tm1. It was measured.

(amount of water)
Using a Karl Fischer titer (manufactured by Mitsubishi Chemical Analytech Co., Ltd., CA-200), the water content of 0.5 g of the sample was measured under the conditions of 280 ° C. and 200 mL / min under a nitrogen stream.

(Melting viscosity)
Using a capillary rheometer (Capillary Graph 1D manufactured by Toyo Seiki Seisakusho Co., Ltd .: piston diameter 10 mm), the apparent melt viscosity was measured in accordance with ISO 11443 under the conditions of a ^{cylinder temperature of 310 ° C. and a shear rate of 1216 sec -1.} An orifice having an inner diameter of 1 mm and a length of 10 mm was used for the measurement.

(Average particle size and maximum particle size)
The average particle size and the maximum particle size were measured using a laser diffraction / scattering type particle size distribution measuring device (LA-920, manufactured by HORIBA, Ltd.). The average particle size is an arithmetic average particle size based on the volume.

(Circularity)
Using a dynamic image analysis method / particle state analyzer (PITA-3, manufactured by Seishin Enterprise Co., Ltd.), the circularity of 4500 fine particles in the polyarylene sulfide resin powder is calculated from the area A and the circumference P as follows. It was calculated from the formula (II) of the above, and the average value was taken as the average circularity of the resin powder.
Circularity = (4 × π × A) / P ² ... (II)

[Evaluation]
(Surface)
The appearance of the hot press molded products obtained in Examples and Comparative Examples was visually observed and evaluated according to the following criteria. The results are shown in Table 1.
Good: The surface of the molded product was smooth and no voids were confirmed.
Defective: The surface of the molded product was rough and voids were confirmed.

(Dispersibility of filler)
The dispersibility of the filler was evaluated using the surface resistance value of the hot press molded product as an index. That is, with respect to the heat-press molded products obtained in Examples and Comparative Examples, the resistivity value was measured at any four locations (manufactured by Mitsubishi Chemical Analytech Co., Ltd., Lorester GP, electrode; PSP probe for microregion measurement). Was measured using. The surface resistance values of the four points measured from the above were calculated by dividing the maximum value by the minimum value as a variation, and evaluated according to the following criteria. The results are shown in Table 1.
Good: The above variation was less than 20.0.
Defective: The above variation was 20.0 or more.

As shown in Table 1, it can be seen that the hot press-molded product of the example using the resin powder according to the present embodiment has excellent dispersibility of the filler and is a high-quality hot press-molded product. Further, since the polyarylene sulfide resin powder is used and its melting point Tm1 is 250 ° C. or higher and 300 ° C. or lower, the heat resistance is excellent.

Claims (6)

100 parts by mass of polyarylene sulfide resin powder, carbon fibers with an average fiber length of 150 μm or less, milled carbon fibers with an average fiber length of 150 μm or less, carbon nanofibers with an average fiber length of 150 μm or less, and an average fiber length of 150 μm or less. It contains 10 to 400 parts by mass of a conductive filler containing at least one selected from the group consisting of carbon nanotubes, carbon black having an average particle size of 500 nm or less, and graphite having an average particle size of 500 nm or less.
The average particle size of the polyarylene sulfide resin powder is 5 μm or more and 100 μm or less, the melting point Tm1 measured by the differential scanning calorimeter is 250 ° C. or more and 300 ° C. or less, and the average circular shape measured by the dynamic image analysis method. degree is 0.70 to 1.00, in the composite material for hot press molded product,
The conductive filler, the average particle size of 1 or more of carbon black and the average particle size of less than or equal to 500nm is selected from the group consisting of graphite 500nm, composites. The composite material according to claim 1, wherein the amount of water measured by the Karl Fischer titer of the polyarylene sulfide resin powder is 0.1 ppm or more and 750 ppm or less. Claim that the melt viscosity measured at a cylinder temperature 30 ° C. higher than the melting point Tm1 measured by a differential scanning calorimeter of polyarylene sulfide resin powder and a shear rate of 1216 sec ^-1 is 10 Pa · s or more and 1000 Pa · s or less. The composite material according to 1 or 2. The composite material according to any one of claims 1 to 3, wherein the ratio of the maximum particle size to the average particle size (maximum particle size / average particle size) of the polyarylene sulfide resin powder is 6.5 or less. .. A hot press molded product using the composite material according to any one of claims 1 to 4. The hot press molded product according to claim 5, which is in the form of a plate having a thickness of less than 5 mm.