JP2002079540A - Injection molding method using carbon dioxide and molding obtained by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding method for a polyphenylene ether resin composition which is excellent in balance among lightweight, heat resistance, flame resistance, dimensional stability, and mechanical properties and improved in fluidity, a molding obtained by the method, and especially an injection molding method which can develop high fluidity even in a thick wall part by adding a liquid crystal polyester. SOLUTION: In the molding method, the resin composition comprising (A) 30-99 pts.wt. of a polyphenylene ether resin 3 and (B) 1-70 pts.wt. of the liquid crystal polyester is injection-molded with at least 0.2 wt.% of carbon dioxide absorbed or dissolved in the resin composition. The molding is obtained by the method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a light-weight, heat-resistant,
The present invention relates to an injection molding method of a polyphenylene ether-based resin composition having an excellent balance of flame retardancy, dimensional stability, and mechanical properties and having greatly improved fluidity, and a molded article obtained by the method.

[0002]

2. Description of the Related Art In general, automotive parts used for parts around an engine of an automobile or around a lamp, or parts for office equipment used for internal mechanical parts such as a copying machine, a printer, a facsimile, etc. From the viewpoint of safety and reliability, heat resistance and flame retardancy are required.
Conventionally, these parts for automobiles and office equipment are
A resin composition in which a flame retardant and a fibrous inorganic filler are added to a crystalline resin represented by T or PBT, or an amorphous material in which a fibrous inorganic filler is added, having a specific gravity of about 1.7 A resin composition has been used. The former crystalline resin composition contains a halogen-based flame retardant, and another resin composition that is environmentally friendly has been desired. On the other hand, the latter amorphous resin composition having a specific gravity of about 1.7 has extremely poor fluidity, and thus produced injection molded articles often have distortion during molding. The distortion remaining in this molded product is
It is generally called "residual distortion".

[0003] For this reason, it is necessary to perform a heating treatment called an annealing treatment for removing and relaxing the residual strain on the molded product produced from the amorphous resin composition. However, since the annealing process is a process performed on a molded product after injection molding, the number of manufacturing processes is further increased, and equipment for the annealing process is required, which means that the burden on the manufacturer is increased. In addition, it is difficult to cope with an increase in demand for office equipment because it is necessary to manage variations in the annealed products.

On the other hand, in the case of a molded article that is not subjected to an annealing treatment, the molded article itself is relaxed by being deformed after molding, so that a dimensional change such as flatness occurs. This causes the dimensional accuracy of the product to decrease. In the conventional injection molding method, the injection pressure changes in proportion to the melt viscosity of the resin used. A resin having a high melt viscosity requires a high injection pressure at the time of resin injection, which results in a large amount of distortion remaining in a molded product.

[0005] As an injection molding method for obtaining high dimensional accuracy with little distortion of a molded product, a method of lowering the melt viscosity of the resin by setting the resin temperature at the time of injection molding, and extending the cooling time in the mold. Methods have been implemented.
By increasing the resin temperature setting, the melt viscosity of the resin can be reduced, so that the pressure can be sufficiently transmitted to the end of the flow, but the volume change of the resin itself during cooling and solidification increases. , Which causes sink marks, voids and the like. In addition, raising the resin temperature requires time for cooling the resin, which may cause a decrease in productivity.

If the cooling is not sufficient, the temperature of the molded product at the time of removal is high. For this reason, after the molded article is taken out from the mold, there is a possibility that volume shrinkage or deformation due to its own weight may occur before the temperature of the molded article itself gradually decreases to the ambient temperature. This causes the dimensional accuracy to deteriorate, which is not preferable. In addition, the method of extending the cooling time in the mold not only lowers the productivity but also often leaves cooling distortion in the molded product due to the volume change generated during cooling. The dimensions may change under the usage environment of the parts for use, and the function may be degraded.

On the other hand, new molding methods such as a high-speed injection molding method and a gas assist molding method have been proposed as methods for producing a molded article requiring dimensional accuracy and dimensional stability. The high-speed injection molding method has the effect of injecting amorphous resin at high speed to prevent the melt viscosity from rising due to cooling from the mold, reduce the melt viscosity with high shear force, and reduce the pressure difference in the cavity. There is. Further, the effect of reducing the injection time is obtained, and the productivity is also improved. However, it is necessary to pay attention to the deterioration of the resin due to the heat generated by shearing, the generation of burrs due to high-speed injection, and the occurrence of resin burn due to adiabatic compression in the gas reservoir at the end of the mold cavity. On the other hand, J.I. Appl. Pol
ym. Sci. , Vol. 30, 2633 (1985)
As shown in many documents, it is known that when carbon dioxide is absorbed into a resin, it acts as a plasticizer for the resin and lowers the glass transition temperature, but is widely applied to resin molding. Has not been reached.

Japanese Patent Application Laid-Open No. 5-318541 discloses that a resin such as carbon dioxide or nitrogen is contained in a thermoplastic resin and the resin is filled into the cavity while removing the gas in the cavity. To improve the fluidity of the molded article and obtain a molded article without deterioration in strength or appearance.
However, in this method, when carbon dioxide is used as the gas, the amount of the gas contained in the resin is small at a maximum of about 0.18% by weight, and it is difficult to obtain a sufficient fluidity improving effect. It can be said that it is difficult to obtain accuracy and dimensional stability.

[0009] WO 98/52734 discloses that
In injection molding of thermoplastic resin,
Shows a method of filling molten resin whose viscosity has been reduced by dissolving more than 1% by weight into a mold cavity that has been kept pressurized with a gas such as carbon dioxide at a pressure higher than the pressure at which foaming does not occur at the flow front of the molten resin. Have been. But,
In this method, since the filling of the resin is inhibited by the pressurized gas in the mold cavity, the pressure at the time of filling increases, which is disadvantageous in obtaining high dimensional accuracy and dimensional stability. In addition, a seal structure for holding the pressurized gas filled in the mold cavity is required. However, it is not easy to create a mold for injection molding and manufacturing a molded article having a complicated shape with a seal structure.

In general, polyphenylene ether is a resin having excellent properties such as heat resistance, hot water resistance, dimensional stability and mechanical and electrical properties. On the other hand, polyphenylene ether has poor moldability due to its high melt viscosity. That is, it has disadvantages such as poor fluidity, poor chemical resistance, and low impact resistance. In order to improve such a drawback of polyphenylene ether, alloying of polyphenylene ether with another resin has been conventionally performed.

For example, it is widely known that alloying polyphenylene ether with polystyrene or high-impact polystyrene improves fluidity. However, problems such as reduced flame retardancy and heat resistance are found. there were. On the other hand, for example, JP-A-56-115357 discloses that
It has been proposed to blend a polymer such as polyphenylene ether with liquid crystal polyester to improve the melt processability of polyphenylene ether, but it is not sufficient. JP-A-2-97555 proposes to incorporate various polyarylene oxides into a liquid crystal polyester for the purpose of improving the solder heat resistance. Further, JP-A-6-122762 discloses that amines are added. It has been proposed to mix a polyphenylene ether modified with the above and a liquid crystal polyester, but none of these methods is sufficient in terms of balance among heat resistance, fluidity, flame retardancy and mechanical properties.

When alloying polyphenylene ether and liquid crystal polyester, addition of an organic silane coupling agent is disclosed in JP-A-5-117505,
Although proposed in Japanese Patent Application Laid-Open No. 9-111103, the fluidity is not sufficient. In addition, Japanese Patent Laid-Open No.
Japanese Patent Publication No. 88 proposes a method of increasing the strength and rigidity of a recycled material, but it is not sufficient in terms of fluidity. In general, the addition of a small amount of liquid crystal polyester to increase the fluidity-imparting effect has a problem in that it is limited to injection molding at a thin portion where a shear is likely to be applied.

[0013]

DISCLOSURE OF THE INVENTION The present invention relates to injection molding of a polyphenylene ether-based resin composition having a good balance of light weight, heat resistance, flame retardancy, dimensional stability, and mechanical properties, and having greatly improved fluidity. It is an object of the present invention to provide a method and a molding obtained thereby. Particularly, it is an object of the present invention to provide an injection molding method in which liquid crystal polyester is added and high fluidity characteristics can be exhibited even in a thick portion.

[0014]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a resin composition containing a specific amount of a polyphenylene ether-based resin and a specific amount of a liquid crystal polyester has been added to a resin composition. By injection molding while absorbing or dissolving carbon, injection pressure can be significantly reduced compared to polyphenylene ether without compounding liquid crystal polyester, light weight, heat resistance, flame retardancy, dimensional stability,
The inventors have found that a molded article having an excellent balance of mechanical properties can be obtained, and have completed the present invention.

That is, the present invention provides: When injection-molding a resin composition comprising (A) 30 to 99 parts by weight of a polyphenylene ether-based resin and (B) 1 to 70 parts by weight of a liquid crystal polyester, 0.2% by weight or more of the resin composition is used. 1. A molding method characterized by performing injection molding while absorbing or dissolving carbon dioxide. 2. a molded article obtained by the molding method described in 1 above; The molded article according to the above 2, wherein the minimum thickness of the molded article is 0.5 mm or more,

4. 4. The molded article according to the above 2, wherein the minimum thickness of the molded article is 1.0 mm or more; 5. The molded article according to any one of the above items 2 to 4, wherein the molded article is a heat-resistant automotive part or a heat-resistant part for office equipment. The molded article according to the above item 5, wherein the heat-resistant part for an automobile is an automobile lamp extension or an automobile lamp reflector,

[7] 7. The molded article according to the above item 5, wherein the heat-resistant part for office equipment is a cover of a fixing device roller of a copying machine. 9. The molding method as described in 1 above, wherein 0.1 to 300 parts by weight of the inorganic filler (C) is added to 100 parts by weight of the total of the components (A) and (B). . The inorganic filler (C) is added in an amount of 0.1 to 300 parts by weight based on 100 parts by weight of the total of the components (A) and (B), and the inorganic filler is added in an amount of 0.1 to 300 parts by weight. A molded article.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The polyphenylene ether-based resin (A) of the present invention refers to a repeating unit structure represented by the formula (1).

[0019]

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(R ₁ and R ₄ are each independently hydrogen,
Represents primary or secondary lower alkyl, phenyl, aminoalkyl, hydrocarbonoxy. R ₂ and R ₃ each independently represent hydrogen, primary or secondary lower alkyl, or phenyl. ), Reduced viscosity (0.5 g / dl, chloroform solution, measured at 30 ° C.)
Is a homopolymer and / or a copolymer in the range of 0.15 to 1.0 dl / g. Preferred reduced viscosities are in the range of 0.20 to 0.70 dl / g, most preferably in the range of 0.40 to 0.60.

Specific examples of the polyphenylene ether resin include poly (2,6-dimethyl-1,4-phenylene ether) and poly (2-methyl-6-ethyl-).
1,4-phenylene ether), poly (2-methyl-6)
-Phenyl-1,4-phenylene ether), poly (2,6-dichloro-1,4-phenylene ether),
And polyphenylene ether copolymers such as copolymers of 2,6-dimethylphenol with other phenols (eg, 2,3,6-trimethylphenol and 2-methyl-6-butylphenol). Coalescence is also included. Among them, poly (2,6-dimethyl-1,4-phenylene ether), 2,6-dimethylphenol and 2,2
A copolymer with 3,6-trimethylphenol is preferred, and poly (2,6-dimethyl-1,4-phenylene ether) is more preferred.

US Pat. No. 3,306,687 is an example of a method for producing (A) the polyphenylene ether used in the present invention.
There is a method in which 2,6-xylenol is oxidatively polymerized using a complex of a cuprous salt and an amine described in the specification of Patent No. 4 as a catalyst. U.S. Pat. Nos. 3,306,875 and 325
Nos. 7357 and 3257358, JP-B-52-17880, JP-A-50-51197 and JP-A-63-152628 also describe (A) a method for producing polyphenylene ether. preferable.

The polyphenylene ether resin (A) of the present invention may be used as it is after the polymerization step,
By using an extruder, under N ₂ gas atmosphere or non-N ₂ gas atmosphere may be used in pelletized by melt kneading with desalted揮下or non de揮下.

The polyphenylene ether resin (A) of the present invention also includes polyphenylene ethers functionalized with various dienophile compounds. Various dienophile compounds include, for example, compounds such as maleic anhydride, maleic acid, fumaric acid, phenylmaleimide, itaconic acid, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, glycidyl acrylate, glycidyl methacrylate, stearyl acrylate, and styrene. No. As a method for functionalization with these dienophile compounds, an extruder or the like may be used in the presence or absence of a radical generator, and may be functionalized in a molten state under devolatilization or non-devolatilization. Alternatively, the functionalization may be performed in a non-molten state in the presence or absence of a radical generator, that is, in a temperature range from room temperature to the melting point. At this time, the melting point of the polyphenylene ether is defined as a peak top temperature of a peak observed in a temperature-heat flow graph obtained when the temperature is increased at 20 ° C./min in a measurement by a differential scanning calorimeter (DSC). If there are a plurality of peak top temperatures, the highest temperature is defined.

The polyphenylene ether resin (A) of the present invention has a number average molecular weight of 1,000 to 100,
000 is preferred. A more preferred range is about 6,000
0 to 60,000. Particularly preferred as an engineering resin application is about 10,000 to 30,000.
0. In addition, the number average molecular weight of the present invention is a number average molecular weight in terms of polystyrene obtained by gel permeation chromatography using a calibration curve of standard polystyrene. When the molecular weight of the polyphenylene ether resin (A) of the present invention is less than 1,000, sufficient impact resistance cannot be obtained, and when it is more than 100,000, sufficient fluidity cannot be obtained.

The (A) polyphenylene ether-based resin of the present invention may contain an aromatic vinyl-based polymer, if necessary, as long as the characteristics and effects of the present invention are not impaired. Examples of the aromatic vinyl polymer include polystyrene, high impact polystyrene, and acrylonitrile-styrene copolymer. The liquid crystal polyester (B) of the present invention is a polyester called a thermotropic liquid crystal polymer, and a known polyester can be used. For example, a thermotropic liquid crystal polyester having p-hydroxybenzoic acid and polyethylene terephthalate as main constitutional units, p-hydroxybenzoic acid and 2-
Thermotropic liquid crystal polyester having hydroxy-6-naphthoic acid as a main structural unit, p-hydroxybenzoic acid, and thermotropic liquid crystal polyester having 4,4'-dihydroxybiphenyl and terephthalic acid as main structural units, and the like. No restrictions. As the liquid crystal polyester (B) used in the present invention, those composed of the following structural units (a) and (b), and if necessary, (c) and / or (d) are preferably used.

[0027]

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[0028]

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[0029]

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[0030]

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Here, the structural units (a) and (b) are a structural unit of a polyester formed from p-hydroxybenzoic acid and a structural unit formed from 2-hydroxy-6-naphthoic acid, respectively. By using the structural units (a) and (b), it is possible to obtain the thermoplastic resin composition of the present invention having excellent balance of mechanical properties such as excellent heat resistance, fluidity and rigidity. X in the above structural units (C) and (D) can be arbitrarily selected from one or two or more types according to the following (Formula 2).

[0032]

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In the structural formula (C), preferred are structural units formed from each of ethylene glycol, hydroquinone, 4,4'-dihydroxybiphenyl, 2,6-dihydroxynaphthalene and bisphenol A, and more preferred are: Ethylene glycol, 4,
Structural units formed from each of 4'-dihydroxybiphenyl and hydroquinone, and particularly preferred are
It is a structural unit formed from each of ethylene glycol and 4,4'-dihydroxybiphenyl. In the structural formula (d), preferred are structural units formed from terephthalic acid, isophthalic acid, and 2,6-dicarboxynaphthalene, and more preferred are structural units formed from terephthalic acid and isophthalic acid. It is.

In the structural formulas (c) and (d), at least one kind of the structural units described above or two or more kinds thereof can be used in combination. Specifically, when two or more kinds are used in combination, in the structural formula (C), 1) a structural unit generated from ethylene glycol / a structural unit generated from hydroquinone, 2) a structural unit generated from ethylene glycol / 4, Structural units generated from 4'-dihydroxybiphenyl; 3) structural units generated from hydroquinone / 4 structural units generated from 4,4'-dihydroxybiphenyl;

Further, in the structural formula (d), 1) a structural unit formed from terephthalic acid / a structural unit formed from isophthalic acid, 2) a structural unit formed from terephthalic acid / 2, formed from 2,6-dicarboxynaphthalene And other structural units. Here, the amount of terephthalic acid is preferably at least 40% by weight, more preferably at least 60% by weight, particularly preferably at least 80% by weight in the two components. By setting the amount of terephthalic acid to 40% by weight or more of the two components, a resin composition having relatively good fluidity and heat resistance can be obtained. The ratio of the amounts of the structural units (a), (b), (c), and (d) in the liquid crystal polyester (B) component is not particularly limited. However, the structural units (c) and (d) are basically in equimolar amounts.

The structural unit (e) composed of the structural units (c) and (d) can be used as the structural unit in the component (B). Specifically, 1) a structural unit generated from ethylene glycol and terephthalic acid, 2) a structural unit generated from hydroquinone and terephthalic acid, 3) 4,
Structural units formed from 4'-dihydroxybiphenyl and terephthalic acid, 4) structural units formed from 4,4'-dihydroxybiphenyl and isophthalic acid, 5) structural units formed from bisphenol A and terephthalic acid, and the like. it can.

[0037]

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The liquid crystal polyester component (B) of the present invention may contain other aromatic dicarboxylic acids, aromatic diols, and aromatic hydroxy carboxylic acids, if necessary, in a small amount that does not impair the features and effects of the present invention. Structural units generated from acids can be introduced. The temperature at which the component (B) of the present invention starts to exhibit a liquid crystal state upon melting (hereinafter referred to as "liquid crystal onset temperature") is preferably 150 to 350C, more preferably 180 to 320C. By setting the liquid crystal onset temperature in this range, the obtained resin composition can have a favorable balance between favorable heat resistance and moldability.

The (B) liquid crystal polyester component 2 of the present invention
The dielectric loss tangent (tan δ) at 5 ° C. and 1 MHz is preferably 0.03 or less, more preferably 0.02 or less.
5 or less. The smaller the value of the dielectric loss tangent, the smaller the dielectric loss, which is preferable because the generated electrical noise is suppressed. In particular, at 25 ° C. under a high frequency region, that is, in a 1 to 10 GHz region, a dielectric loss tangent (tan δ)
Is preferably 0.03 or less, more preferably 0.025 or less.

The apparent melt viscosity (liquid crystal onset temperature + 30 ° C., shear rate 100 / sec) of the liquid crystal polyester component (B) of the present invention is preferably 100 to 30,000 poise, more preferably 100 to 20,000. Poise, particularly preferably 100 to 10,000 poise. Controlling the apparent melt viscosity in this range may make the resulting composition flowable. The thermal conductivity of the component (B) of the present invention in a molten state (liquid crystal state) is preferably 0.1 to 2.0 W / mK, more preferably 0.2 to 2.0 W / mK.
1.5 W / mK, particularly preferably 0.3 to 1.0 W / m
K. By setting the thermal conductivity in the molten state (liquid crystal state) within this range, the injection molding cycle of the obtained composition can be relatively shortened.

The amount of the polyphenylene ether resin (A) in the present invention is 30 to 99 parts by weight, preferably 35 to 98 parts by weight, and more preferably 40 to 95 parts by weight. If the amount is more than 99 parts by weight, the fluidity is greatly reduced. If the amount is less than 30 parts by weight, the specific gravity increases, which is not preferable for weight reduction. The compounding amount of the liquid crystal polyester (B) in the present invention is 70 to 1 part by weight, preferably 65 to 2 parts by weight, and more preferably 60 to 5 parts by weight. If the amount is more than 70 parts by weight, the specific gravity becomes large, which is not preferable for reducing the weight, and increases the cost. If the amount is less than 1 part by weight, sufficient fluidity cannot be obtained.

The inorganic filler (C) of the present invention includes, as specific gravity adjusters, inorganic salts, oxides, metal powders, and the like, such as barium sulfate, red iron oxide, and tungsten powder. Further, as a strength imparting agent, glass fiber, metal fiber, potassium titanate, carbon fiber, silicon carbide, ceramic, silicon nitride, mica, nepheline sinite, talc, wollastonite, slag fiber, ferrite, glass beads,
Inorganic compounds such as glass powder, glass balloon, quartz, quartz glass and the like can be mentioned. Among them, glass fibers and carbon fibers are preferably used in view of the balance among fluidity, heat resistance and mechanical properties, and glass fibers are more preferably used. The shape of these inorganic fillers is not limited, and fibrous, plate-like, and spherical shapes can be arbitrarily selected.

These inorganic fillers may be used in combination of two or more specific gravity adjusters and / or strength imparting agents. Further, if necessary, it can be used after being pre-treated with a coupling agent such as a silane-based or titanium-based coupling agent. The addition amount of the (C) inorganic filler of the present invention is:
For the total of 100 parts by weight of the components (A) and (B),
0.1 to 300 parts by weight, preferably 1 to 200 parts by weight, more preferably 5 to 100 parts by weight. If the amount is less than 0.1 part by weight, the effect of imparting strength is not sufficiently exhibited, and if it is more than 300 parts by weight, sufficient fluidity cannot be obtained.

In the present invention, in addition to the above-mentioned components, other additional components such as an antioxidant and a flame retardant (organic phosphoric acid ester-based compound) may be used, if necessary, as long as the characteristics and effects of the present invention are not impaired. , Inorganic phosphorus compounds, silicon compounds, phosphazene compounds, etc.), elastomers (ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / propylene / non-conjugated diene copolymer,
Olefin copolymers such as ethylene / ethyl acrylate copolymer, ethylene / glycidyl methacrylate copolymer, ethylene / vinyl acetate / glycidyl methacrylate copolymer, ethylene / propylene-g-maleic anhydride copolymer, and ABS Copolymer, polyester polyether elastomer, polyester polyester elastomer, vinyl aromatic compound-conjugated diene compound block copolymer, hydrogenated product of vinyl aromatic compound-conjugated diene compound block copolymer), plasticizer (oil, low molecular weight polyethylene) Epoxidized soybean oil, polyethylene glycol, fatty acid esters, etc.), flame retardant aids, weather (light) improvers, nucleating agents for polyolefins, slip agents, various colorants, release agents, etc. It doesn't matter.

The resin composition of the present invention can be produced by various methods. For example, a heat-melt kneading method using a single-screw extruder, a twin-screw extruder, a roll, a kneader, a Brabender plastograph, a Banbury mixer, or the like can be mentioned. Among them, a melt-kneading method using a twin-screw extruder is most preferable. The melt-kneading temperature at this time is not particularly limited, but can be arbitrarily selected usually from 150 to 350 ° C. The molding method of the present invention can significantly improve fluidity by absorbing or dissolving carbon dioxide in the resin composition before filling the resin composition of the present invention into a mold cavity. Is the way.

At this time, the amount of carbon dioxide absorbed or dissolved is preferably 0.2% by weight or more based on the resin composition used. 0.2% by weight of absorption or dissolution
The above is preferable because the fluidity at the time of filling the resin composition into the mold cavity is improved, so that an increase in resin pressure can be suppressed. If the amount of absorption or dissolution of carbon dioxide is less than 0.2% by weight,
It is difficult to obtain a fluidity improving effect by absorbing or dissolving carbon dioxide, and it is difficult to obtain sufficient dimensional accuracy and dimensional stability, which is not preferable.

In the present invention, 0.2% by weight or more of carbon dioxide is absorbed or dissolved in the resin composition of the present invention. Examples of the method include a method of mixing the resin in a molten state in a heating cylinder of an injection molding machine, a method of mixing the resin in a molten state from a nozzle portion of the molding machine, and a method of mixing carbon dioxide between a mold and a nozzle of the molding machine. Providing equipment for the supply of, a method of mixing the resin in a molten state, a method of granulating resin pellets in a state where carbon dioxide is mixed in the resin in a molten state in advance, and a method of injection molding using this, Alternatively, there is a method of absorbing carbon dioxide into resin pellets in a closed container such as a hopper of a molding machine in advance.

The carbon dioxide can be easily dispersed uniformly in the resin composition of the present invention, the absorption or dissolution can be easily adjusted, the setup before molding is not complicated, and the hopper of the molding machine has a pressure-resistant structure. Considering that it is not necessary to provide a facility for supplying carbon dioxide in the heating cylinder of the injection molding machine, at the nozzle of the molding machine, or at any position between the nozzle of the molding machine and the mold And a method of mixing carbon dioxide into the molten resin composition.

In the present invention, the amount of carbon dioxide absorbed or dissolved is measured by the following method. 1) Measure the weight of the molded article immediately after molding (M1). 2) Put the molded product in a hot air dryer kept at 100 ° C for 48 hours.
Leave for more than an hour to allow carbon dioxide to escape. The weight of the molded product taken out of the hot air dryer is measured (M2). 3) The absorption amount (Q) (% by weight) of CO ₂ was calculated as (M1-M
2) Calculate from ÷ M2 × 100.

In the present invention, after absorbing or dissolving carbon dioxide in the resin composition, the resin composition may be injected into a mold cavity which is substantially at atmospheric pressure without pressurizing the inside of the mold cavity in advance. preferable. This is because the filling pressure is increased because the filling of the resin is hindered by the pressurized gas in the cavity, which is disadvantageous for obtaining high dimensional accuracy and long-term stability of the dimensions. In addition, a seal structure for maintaining the pressure of the pressurized gas filled in the mold cavity is required, and a mold for molding the molded body of the present invention, which is often seen to have a complicated shape, is created. It is difficult to do so.

The minimum thickness of the molded article of the present invention is preferably 0.5 mm or more. More preferably, it is 1.0 mm or more. If the minimum thickness is less than 0.5 mm, the filling pressure is too high, and it is difficult to eliminate molding distortion. In general, when carbon dioxide is not used,
When the minimum thickness of the molded article is 0.5 mm or more, for example, about 4 mm, it becomes difficult to obtain a shear. Even if the liquid crystal polyester of the component (B) is added, the injection molding and filling of only the polyphenylene ether resin of the component (A) is performed. It doesn't change much with pressure. However, even with a thickness of about 4 mm, the presence of carbon dioxide allows the resin composition of the present invention to exhibit a large filling pressure reducing effect as compared to the case of using only the component (A) polyphenylene ether-based resin. .

The molded article of the present invention is suitable for heat-resistant parts for automobiles or heat-resistant parts for office equipment. Heat-resistant parts for automobiles include, for example, alternator terminals, alternator connectors, IC regulators, potentiometer bases for light days, various valves such as exhaust gas valves, various fuel-related / exhaust / intake systems pipes, air intake nozzle snorkels, intake manifolds, fuel Pump, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, coolant sensor, oil temperature sensor, brake pad wear sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake butt wear sensor, air conditioner Thermostat base, heating hot air flow control valve, brush holder for radiator motor, warpー Pump impellers, turbine vanes, parts related to wiper motors, dust distributors, starter switches, starter relays, transmission wire harnesses, window washer nozzles, air conditioner panel switch boards, fuel related electromagnetic valve coils, fuse connectors, horn terminals Preferred are components such as an electrical component insulating plate, a step motor rotor, a brake piston, a solenoid bobbin, an engine oil filter, an ignition device case, a wheel cap, a lamp socket, a lamp housing, a lamp extension, a lamp reflector, and the like. Among them, a lamp extension and a lamp reflector are preferred in view of a balance among lightness, heat resistance, flame retardancy and mechanical properties.

The heat-resistant part for office equipment of the present invention is, for example,
It is suitable for home and office electrical product parts, office computer-related parts, telephone-related parts, facsimile-related parts, copier-related parts and the like represented by air conditioner parts, typewriter parts, word processor parts and the like. Among them, facsimile-related parts, copier-related parts, and the like are preferable. Further, the roller portion of a toner fixing machine such as a copying machine or a facsimile can reach a temperature of 150 ° C. or more, and further reach a temperature of 170 ° C. or more and about 200 ° C., so that heat resistance and flame retardancy are required. Therefore, it is suitable for a fixing machine roller cover of a copying machine.

The shape of the molded article of the present invention is not particularly limited as long as it is a shape suitable for the purpose. For example, a disk shape, a donut shape, a conical shape, a ring shape, a box shape, or a composite thereof can be used. Shape and the like. As described above, in the present invention, a resin composition containing a specific amount of (A) a polyphenylene ether-based resin and a specific amount of (B) a liquid crystal polyester is injection-molded while absorbing or dissolving carbon dioxide. It was found that the injection pressure can be greatly reduced as compared with polyphenylene ether containing no liquid crystal polyester, and a molded article having excellent balance of light weight, heat resistance, flame retardancy, dimensional stability, and mechanical properties can be obtained. In particular, it has been found that in the injection molding in which the minimum thickness of the molded body is 0.5 mm or more, the injection filling pressure by carbon dioxide is greatly reduced. Hereinafter, the present invention will be described based on examples. However, the present invention is not limited to the following embodiments.

[0055]

[Production Example 1] Polyphenylene ether (PPE-1)
Production example of powdery poly (2,6-dimethyl-) having a reduced viscosity of 0.42 obtained by oxidative polymerization of 2,6-dimethylphenol
1,4-phenylene ether). The number average molecular weight was 17,300.

[0056]

[Production Example 2] Production example of polyphenylene ether (PPE-2) functionalized in a molten state Poly (2,6-dimethyl-) having a reduced viscosity of 0.42 obtained by oxidative polymerization of 2,6-dimethylphenol. 1,4-phenylene ether) (hereinafter abbreviated as (a-1)) is used as a raw material. With respect to 100 parts by weight of the polyphenylene ether (a-1), maleic anhydride and 0.3 part by weight of 2,5-dimethyl-2,
5-bis (t-butylperoxy) hexane at 300 ° C
The reaction was carried out by melt-kneading while degassing with a twin-screw extruder set as described above, and the resulting pellets were pulverized and washed with acetone to perform a polyphenylene functionalization in a molten state. Ether (PPE
-2) was obtained. It was confirmed that the added amount of maleic anhydride was 0.4 parts by weight. The number average molecular weight is 18,700
Met.

[0057]

Production Example 3 Production Example of Liquid Crystal Polyester (LCP-1) Under a nitrogen atmosphere, p-hydroxybenzoic acid, 2-
Hydroxy-6-naphthoic acid and acetic anhydride were charged, heated and melted, and polycondensed to obtain a liquid crystal polyester (LCP-1) having the following theoretical structural formula. In addition, the component ratio of a composition represents a molar ratio.

[0058]

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[0059]

Production Example 4 Production Example of Liquid Crystal Polyester (LCP-2) Under a nitrogen atmosphere, p-hydroxybenzoic acid, polyethylene terephthalate, and acetic anhydride were charged, heated and melted, and polycondensed to obtain the following theoretical structural formula. Having a liquid crystal polyester (LCP-2). In addition, the component ratio of a composition represents a molar ratio.

[0060]

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The molding and evaluation of the physical properties of each resin composition were carried out according to the following methods. (1) Molding The obtained pellets were heated at a cylinder temperature of 330/330 /
The molding was performed using an injection molding machine ["TR50S2A", manufactured by Sodick Plustech Co., Ltd.] set at 320/310 ° C and a mold temperature of 90 ° C. Here, the primary filling amount of the injection molding is set at the measuring position and the holding pressure switching position so that the product portion of the mold cavity is almost filled and the tab portion at the flow end of the test piece is almost completely missing. did. Here, the pressure-holding switching position is a position where the pressure is switched from the primary filling process to the pressure-holding process.

The injection speed of the primary filling is an injection speed from the measuring position to the holding pressure switching position, and is 50 m
m / sec. In addition, in order to make the pressure state of each material test piece uniform, the holding pressure was set to 70% of the injection filling pressure, and the holding time was 3 seconds and the cooling time was 20 seconds as standard conditions for molding.
The fluidity is determined by measuring the injection filling pressure at the time of primary filling when molding a dumbbell test piece (thickness 4 mm) according to ISO standard.
The display value on the molding machine monitor was read. A pressure gauge is provided near the cylinder and the nozzle for carbon dioxide set in the middle of the cylinder, and the pressure of the charged carbon dioxide (hereinafter referred to as “CO2
₂ Filling pressure ". ) Was measured.

The amount of carbon dioxide absorbed or dissolved (hereinafter sometimes abbreviated as “CO ₂ absorption (Q) (% by weight)”) was measured as follows. The test piece used was an ISO standard dumbbell test piece (4 mm thick). 1) Measure the weight of the molded article immediately after molding (M1). 2) Put the molded product in a hot air dryer kept at 100 ° C for 48 hours.
Leave for more than an hour to allow carbon dioxide to escape. The weight of the molded product taken out of the hot air dryer is measured (M2). 3) The absorption amount (Q) (% by weight) of CO ₂ was calculated as (M1-M
2) Calculate from ÷ M2 × 100.

(2) Specific gravity A having a thickness of 3.2 mm × a length of 127 mm × a width of 12.7 mm
Formed into STM tank test pieces, cut out part of them,
Electronic hydrometer (ED-120T, Mirage Trading Co., Ltd.)
Was used to measure the specific gravity at 23 ° C.

(3) Heat resistance (heat sag) Using the same test piece as in the above (2), a portion 27 mm from one end in the length direction was sandwiched between steel plates from above and below and fixed.
A 100 mm portion in the length direction of the test piece protruded horizontally. This was placed in an oven set at 170 ° C. for 4 hours. Thereafter, the entire fixing plate was taken out and allowed to cool to room temperature, and then the amount of deflection at the non-fixing side end was measured and evaluated according to the following criteria. ：: The amount of deflection is less than 1 mm. X: The deflection amount is 1 mm or more.

(4) Flame Retardancy A 4 mm thick ISO standard dumbbell test piece was cut out into a sack shape, and a combustion test was performed in accordance with UL-94. 1
After the flame contact for 0 seconds, the burning time from the release of the flame to the disappearance of the flame is defined as t ₁ (second). After the flame contact for 10 seconds again, the combustion time from the release of the flame to the disappearance of the flame is t _2. (Seconds)
The test was carried out on five test pieces, and the average burning time at t ₁ and t ₂ was T
(Seconds), the largest _one of t ₁ and t ₂ is Tmax,
Evaluation was made according to the following criteria. V-0: Average burning time (T) is 5 seconds or less, Tmax is less than 10 seconds, and there is no dripping. V-1: Average combustion time (T) is 25 seconds or less, and Tmax
No dripping in less than 30 seconds. V-2: Burning time comparable to V-0 or V-1, but with dripping.

(5) Dimensional stability (degree of shrinkage) The thickness of the center part of the test piece on the gate side and the end side of the 4 mm thick ISO dumbbell test piece was measured with a micro gauge, and the average value was defined as t. The dimensional stability (degree of sink) was evaluated according to the equation. The smaller the sink value, the better the dimensional stability. (Degree of sink) (%) = (4.0−t) /4.0×100

(6) Evaluation of mechanical properties (6-1) Bending properties Using an autograph (AG-5000, manufactured by Shimadzu Corporation), an ISO dumbbell test piece having a thickness of 4 mm, a distance between spans of 64 mm and a test speed of 2 mm / Min., A three-point bending test was performed, and the flexural modulus (FM) and flexural strength (F
S) was measured. (6-2) Tensile Characteristics Using an autograph (AG-5000, manufactured by Shimadzu Corporation), a 4 mm-thick ISO dumbbell test piece was used to perform a tensile test at a chuck-to-chuck distance of 115 mm and a test speed of 50 mm / min. The tensile modulus (TM) and the tensile strength (TS) were measured.

[0069]

Examples 1 to 4 Polyphenylene ether (PPE-
1, or PPE-2) and liquid crystal polyester (LCP-
1 or LCP-2) as shown in Table 1 (parts by weight)
And a twin-screw extruder with a vent port set at 250 to 310 ° C (ZSK-25; WERNER & PFLEIDE)
(Made by RER Co., Ltd.) to obtain pellets. Using these pellets, CO 2 is produced by the method shown above.
_2. Forming was performed by changing the filling pressure as shown in Table 1, and physical properties were evaluated. Table 1 shows the results.
It was shown to.

[0070]

Comparative Example 1 Molding was performed in the same manner as in Example 1 except that carbon dioxide was not used during injection molding, and physical properties were evaluated. The results are shown in Table 1.

[0071]

Example 5 Pellets were obtained in the same manner as in Example 4, except that glass fiber (average length 3 mm, chopped fiber; abbreviated as "GF" in the table) was used as the component (C). . Using the pellets, molding was performed by the method described above, and physical properties were evaluated. Table 1 shows the results.
It was shown to.

[0072]

Comparative Example 2 Powder-like polyphenylene ether (PPE-1) alone was used without using liquid crystal polyester.
Except that a pellet was obtained in a ratio of 0 parts by weight, and this pellet was used, except that it was not filled with carbon dioxide,
The molding was performed in the same manner as in Example 1. CO ₂ absorption (Q)
Was 0 (%) and the injection filling pressure was 1090 (kg / cm ² ).

[0073]

Comparative Example 3 Powder-like polyphenylene ether (P
A pellet was formed in the same manner as in Comparative Example 2 except that a pellet was obtained by using only PE-1) at a ratio of 100 parts by weight, and that the pellet was used and the filling pressure of carbon dioxide was 4 (MPa). . The absorption amount (Q) of CO ₂ is 0.40 (%)
The injection filling pressure was 980 (kg / cm ² ).

[0074]

Comparative Example 4 Powder-like polyphenylene ether (P
A pellet was formed in the same manner as in Comparative Example 2 except that a pellet was obtained by using only PE-1) at a ratio of 100 parts by weight, and that the pellet was used and the filling pressure of carbon dioxide was 8 (MPa). . The absorption amount (Q) of CO ₂ is 0.63 (%)
The injection filling pressure was 950 (kg / cm ² ).

[0075]

Comparative Example 5 Powder-like polyphenylene ether (P
A pellet was formed in the same manner as in Comparative Example 2 except that a pellet was obtained by using only PE-1) at a ratio of 100 parts by weight, and the pellet was used and the filling pressure of carbon dioxide was set to 12 (MPa). . The absorption amount (Q) of CO ₂ is 1.09
(%), The injection filling pressure was 900 (kg / cm ² ).

[0076]

[Table 1]

FIG. 1 shows plots of the filling pressure of carbon dioxide and the injection filling pressure of injection molding in Examples 1 to 3 and Comparative Examples 1 to 5, respectively. As can be seen from FIG. 1, when the liquid crystal polyester of the component (B) is blended, the injection filling pressure reduction effect by carbon dioxide is more exhibited as compared with only the polyphenylene ether resin of the component (A). I understand. Table 1 also shows that dimensional stability is excellent. As can be seen from a comparison between Comparative Example 1 and Comparative Example 2, when forming a relatively thick portion having a thickness of 4 mm, in the absence of carbon dioxide, only the polyphenylene ether-based resin (A) was used ( Comparative Example 2),
It can be seen that in the case of the resin composition in which the liquid crystal polyester of the component (B) was blended with the component (A) (Comparative Example 1), there was no large difference in the injection filling pressure.

As can be seen from FIG. 1 and Table 1, a liquid crystal is prepared by injection molding while absorbing or dissolving carbon dioxide in a resin composition containing a specific amount of polyphenylene ether resin and a specific amount of liquid crystal polyester. Molding that can significantly reduce the injection filling pressure compared to polyphenylene ether without polyester, and has a better balance of light weight, heat resistance, flame retardancy, dimensional stability, and mechanical properties than when carbon dioxide is not used It turns out that the body is obtained.

[0079]

According to the present invention, a method for injection-molding a polyphenylene ether-based resin composition having a good balance of lightness, heat resistance, flame retardancy, dimensional stability, and mechanical properties, and having greatly improved fluidity, and It has become possible to provide the obtained molded article. In addition, it has become possible to provide an injection molding method in which liquid crystal polyester is particularly added and high fluidity characteristics can be exhibited even in a thick portion.

[Brief description of the drawings]

FIG. 1 In Examples 1 to 3 and Comparative Examples 1 to 5,
The horizontal axis represents the filling pressure (MPa) of carbon dioxide, and the vertical axis represents the injection filling pressure (kg / cm ² ) of the injection molding.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/20 101 G03G 15/20 101 // B29K 67:00 B29K 67:00 71:00 71:00 B29L 31:00 B29L 31:00 F term (reference) 2H033 AA23 AA31 BA05 4F071 AA45 AA48 AA51 AH07 AH16 BA01 BB05 BC07 4F206 AA24 AA32 AB11 AB15 AE10 AH04 AH17 JA07 JE30 4J002 CF08X CF16X CF18X CF19FD206

Claims (9)

[Claims] 1. A polyphenylene ether resin (A)
When injection-molding a resin composition comprising 0 to 99 parts by weight and (B) 1 to 70 parts by weight of a liquid crystal polyester, 0.2% by weight or more of carbon dioxide is absorbed or dissolved in the resin composition. A molding method characterized by performing injection molding in a state where the molding is performed. 2. A molded article obtained by the molding method according to claim 1. 3. The molded article according to claim 2, wherein the minimum thickness of the molded article is 0.5 mm or more. 4. The molded article according to claim 2, wherein the minimum thickness of the molded article is 1.0 mm or more. 5. The molded article according to claim 2, wherein the molded article is a heat-resistant part for an automobile or a heat-resistant part for office equipment. 6. The molded article according to claim 5, wherein the heat-resistant component for a vehicle is a lamp extension for a vehicle or a lamp reflector for a vehicle. 7. The molded article according to claim 5, wherein the heat-resistant part for office equipment is a cover of a fixing device roller of a copying machine. 8. The method according to claim 1, wherein 0.1 to 300 parts by weight of the inorganic filler (C) is added to 100 parts by weight of the total of the components (A) and (B). Molding method. 9. The composition according to claim 2, wherein 0.1 to 300 parts by weight of the inorganic filler (C) is added to 100 parts by weight of the total of the components (A) and (B). The molded article according to any one of the above.