JP5717347B2 - Liquid crystalline resin composition for injection molding, molded product and method for improving blister resistance - Google Patents

Description

  The present invention relates to a liquid crystalline resin composition for injection molding capable of suppressing the generation of blisters even when molded under a condition where the injection capacity is large, the molded product formed by molding the resin composition, and the blister resistance of the molded product. On how to improve.

  A group of plastics called engineering plastics has high strength and is being replaced by metal parts. Among them, a group of plastics called liquid crystalline resins melts while maintaining the crystal structure, so the volume changes between melting and solidification due to the high strength based on the crystal structure and the fact that the crystal structure does not change significantly during solidification. Is small and molding shrinkage is small.

  The liquid crystalline resin as described above is excellent in moldability and heat resistance, and is preferably used as a constituent material for small electronic components. Among them, the liquid crystalline resin is suitably used for electronic parts such as connectors because it generates less gas, has excellent hydrolysis resistance, and has good electrical characteristics. In particular, when a liquid crystalline resin is used as a material for an electronic component such as a connector, a method of incorporating glass fiber is known in order to improve the deflection temperature under load.

  In particular, a liquid crystalline polyesteramide resin containing glass fibers is a very preferable material as a material for electronic parts such as connectors. However, when the injection capacity is changed to a large condition in order to improve the productivity of electronic parts, the liquid crystalline resin composition for injection molding that is in a molten state at the time of molding encloses the gas generated from air or material, thereby forming the molding. Bubbles are contained inside the body. When bubbles are contained inside the molded body, the molded product is exposed to a high temperature by a subsequent heat treatment or the like, whereby air or gas in the bubbles expands and the surface of the molded product expands. The swelling of the surface of the molded product is a molding defect called blister, and improvement is required.

  As countermeasures for suppressing the occurrence of blisters as described above, sufficiently deaerate from the vent hole at the time of melt extrusion of the liquid crystalline resin composition for injection molding, and do not allow the resin composition to stay in the molding machine for a long time during molding. And so on. However, the occurrence of blisters cannot be sufficiently suppressed only by changing the conditions during molding.

  Therefore, in order to suppress the generation of blisters, improvement of the liquid crystalline resin composition for injection molding, improvement of the liquid crystalline resin composition for injection molding, improvement of molding conditions, and the like have been performed. For example, Patent Document 1 discloses a specific liquid crystal for injection molding containing a specific amount of an inorganic filler in a kneading machine having an open port for removing volatile components from a material to be kneaded and a pair of two screws. In a method for producing a molded product having a deflection temperature under load of 230 ° C. or higher obtained by melt-kneading a resin composition, a method for producing a molded product is disclosed in which the screw engagement rate of the kneader is adjusted to 1.60 or higher. According to the technique described in Patent Document 1, a liquid crystalline resin composition for injection molding having excellent blister resistance while maintaining basic heat resistance such as melting point and deflection temperature under load of the liquid crystalline resin composition for injection molding. It can be provided.

  However, in the method described in Patent Document 1, the manufacturing conditions of the molded body are extremely complicated. Further, the liquid crystalline polyesteramide resin is a raw material that easily generates blisters as compared with a wholly aromatic polyester resin or the like. For this reason, further improvement is requested | required also about the effect which suppresses generation | occurrence | production of a blister.

JP 2003-211143 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a technique for easily suppressing the generation of blisters even under conditions where the injection capacity is large.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, it contains a liquid crystalline polyesteramide resin and a mixture of fibrous inorganic filler and glass beads, and the ratio of the fibrous inorganic filler and glass beads in this mixture is 0.9: 1. In order to complete the present invention, it is found that a liquid crystalline resin composition for injection molding of 0 to 1.0: 0.9 (hereinafter sometimes simply referred to as “resin composition”) can solve the above-mentioned problems. It came. More specifically, the present invention provides the following.

  (1) It includes a mixture of a liquid crystalline polyesteramide resin, a fibrous inorganic filler, and glass beads, and the ratio of the fibrous inorganic filler to the glass beads in the mixture is 0.9: 1.0. To 1.0: 0.9, a liquid crystalline resin composition for injection molding.

  (2) The liquid crystalline resin composition for injection molding according to (1), wherein the fibrous inorganic filler is glass fiber.

  (3) The liquid crystalline resin composition for injection molding according to (1) or (2), wherein a fiber length of the fibrous inorganic filler is 200 μm or more.

  (4) The liquid crystalline resin composition for injection molding according to any one of (1) to (3), wherein the mixture is contained in an amount of 39 parts by mass to 69 parts by mass with respect to 100 parts by mass of the liquid crystalline polyesteramide resin.

  (5) The melting point of the liquid crystalline polyesteramide resin is 320 ° C. or higher, and the liquid crystalline resin composition for injection molding according to any one of (1) to (4) is molded. A molded article having a deflection temperature under load of 1.8 MPa measured by a method conforming to the above is 260 ° C. or higher.

  (6) The liquid crystalline resin composition for injection molding according to any one of (1) to (4) is molded, and the surface layer of the molded product (from the molded product surface to 0.2 mm) and the central part of the molded product ( A molded product having a difference in linear expansion coefficient at the center of the molded product (0.2 mm) of 0.7 or less.

  (7) By containing a fibrous inorganic filler and glass beads in the liquid crystalline resin composition, and making the content of the fibrous inorganic filler substantially equal to the content of the glass beads A method for improving the blister resistance of a resin molded product.

  According to the present invention, an injection capacity is obtained by injection-molding a liquid crystalline resin composition for injection molding comprising a fibrous inorganic filler and glass beads of substantially the same amount as the fibrous inorganic filler. Even under large conditions, it is possible to suppress the occurrence of blisters on the surface of the obtained molded body. That is, according to the present invention, a high-quality molded product can be produced with high productivity.

It is a figure which shows the cross section of the test piece produced based on ISO1 / 32 ''. It is a figure which shows the state to which the runner, the sprue, and the nozzle were connected.

  Hereinafter, an embodiment of the present invention will be described in detail. However, the present invention is not limited to the following embodiment, and may be implemented with appropriate modifications within the scope of the object of the present invention. it can.

<Liquid crystalline resin composition for injection molding>
The liquid crystalline resin composition for injection molding of the present invention is characterized by containing a liquid crystalline polyesteramide resin, a fibrous inorganic filler, and glass beads. First, these materials will be described below.

[Liquid crystalline polyester amide resin]
When a liquid crystalline polyesteramide resin is used among liquid crystalline resins, blisters are likely to occur in the molded product. One of the features of the present invention is that the occurrence of blisters can be sufficiently suppressed even when a liquid crystalline polyester amide resin that easily generates blisters is used. The preferred liquid crystalline polyesteramide resin exemplified below is a preferred resin in that the physical properties of the resulting molded article can be improved. In the present invention, when a preferable resin as described below is used, it is possible to suppress the generation of blisters while maintaining the physical properties of the molded article (almost without reducing) even when molded under conditions with a large injection capacity. It is a feature.

  The liquid crystalline polyesteramide resin used in the present invention is not particularly limited, and a conventionally known one can be used, but has a melting point in the range of 270 to 370 ° C. and can form an optically anisotropic melt phase. A melt processable polyesteramide having The property of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarizing microscope and observing a molten sample placed on a Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times. When the liquid crystalline polyester amide resin applicable to the present invention is inspected between crossed polarizers, the polarized light is normally transmitted even in a molten stationary state, and optically anisotropic.

  The liquid crystalline polyesteramide resin used in the present invention has a property capable of forming an optically anisotropic melt phase as described above, and preferably has a specific structural unit.

  Examples of the monomer constituting the liquid crystalline polyesteramide resin include aromatic hydroxycarboxylic acid, aromatic carboxylic acid, aromatic diol and the like. In addition to these monomers, those containing one or more of 4-aminophenol, 1,4-phenylenediamine, 4-aminobenzoic acid and derivatives thereof are preferred. And it is further more preferable that an amide component is contained in the ratio of 2-35 mol% in all the coupling | bondings. Further, it is more preferable that the amide component is contained in the total bond in a proportion of 4 to 25 mol%.

  Examples of the aromatic hydroxycarboxylic acid include 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Examples of the aromatic carboxylic acid include terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the like. Examples of the aromatic diol include 2,6-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, hydroquinone, resorcin and the like. In addition, derivatives of these compounds are also exemplified as monomers.

  Examples of the monomer for including the amide component in a proportion of 2 to 35 mol% include the aforementioned 4-aminophenol, 1,4-phenylenediamine, 4-aminobenzoic acid, and derivatives thereof such as 4-acetoxy-aminophenol. Is mentioned.

Specifically, the wholly aromatic polyester amide obtained by copolymerizing the following (i) to (iii) monomers within the range described below is preferable as the liquid crystalline polyester amide resin.
(I) 6-hydroxy-2-naphthoic acid; 30-90 mol%
(Ii) 4-aminophenol; 15-35 mol%
(Iii) terephthalic acid; 15-35 mol%
Also preferred are wholly aromatic polyester amides obtained by copolymerizing the following (i) to (v) monomers within the ranges described below.
(I) The amount of 6-hydroxy-2-naphthoic acid (iv) 4-hydroxybenzoic acid (i) + (iv) is 30 to 90 mol%
(Ii) 4-aminophenol; 2-35 mol%
(Iii) Terephthalic acid; 5-35 mol%
(V) Bisphenol; 2 to 35 mol%

[Fibrous inorganic filler]
The fibrous inorganic filler that can be used in the present invention is not particularly limited, and conventionally known fillers can be used. One of the major purposes of incorporating the fibrous inorganic filler is to suppress the generation of blisters in combination with glass beads described later. Another object is to give physical properties such as sufficient deflection temperature to the molded product that will be the final product.

  Usable fibrous inorganic fillers are glass fiber, asbestos fiber, silica fiber, silica / alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, wollastonite Furthermore, metal fibrous materials such as stainless steel, aluminum, titanium, copper, and brass can be used. Among these, the use of glass fiber is particularly preferable.

The fiber length of the fibrous inorganic filler is not particularly limited, but is preferably 200 μm or more and 700 μm or less, particularly 400 μm or more, in order to impart physical properties such as sufficient deflection temperature under load and ensure good fluidity. 650 μm or less is preferable. Here, the fiber length refers to the fiber length in the kneaded pellet of the liquid crystalline resin composition before injection molding. In addition, the fiber length measured with the following method is employ | adopted for fiber length.
(Measuring method)
For the measurement, an image processing analyzer LUZEX AP (manufactured by Nireco Corporation) was used. The measurement was performed according to the following procedures (1) to (6).
(1) About 2 g of the kneaded pellet of the liquid crystalline resin composition is heated at 600 ° C. for 3 hours to be incinerated.
(2) 3 mg of the ash content of the kneaded pellet of the liquid crystalline resin composition is weighed and dispersed in a 5% aqueous solution of polyethylene glycol.
(3) Collect 5 ml of the dispersion and pour it uniformly into a petri dish.
(4) Capture an image using a stereomicroscope (10 ×) (n = 9)
(5) Each captured image is binarized, and the size of the filler is measured using the image processing analyzer. At that time, a value of 100 μm or less is cut so as not to be affected by the size of the glass beads.
(6) The weight average of the measured values is taken as the fiber length of the fibrous inorganic filler.

  In particular, when molding an electronic component such as a connector, it is necessary to apply a sufficient load deflection temperature to the molded body. In this case, glass fibers having a fiber length in the above preferred range are used as the fibrous inorganic filler, and the glass fiber content is 10 parts by mass or more and 100 parts by mass with respect to 100 parts by mass of the liquid crystalline polyesteramide resin. Part or less.

[Glass beads]
The glass beads that can be used in the present invention are not particularly limited, and conventionally known ones can be used. For example, glass beads having an average particle diameter of about 5 μm or more and 50 μm or less can be preferably used.

  The preferred content of the glass beads contained in the resin composition of the present invention is determined by the preferred content of the fibrous inorganic filler and the content ratio of the fibrous inorganic filler and glass beads described later.

[blend]
The mixture is a mixture of the fibrous inorganic filler and the glass beads. The present invention is greatly characterized in that it is a resin composition for injection molding containing a mixture of a fibrous inorganic filler and glass beads.

  In the present specification, in the description of the liquid crystalline resin composition for injection molding according to the present invention, the liquid crystalline polyester amide resin and the mixture of fibrous inorganic filler and glass beads are described separately. The resin composition of the present invention is limited to a resin composition obtained by previously mixing a fibrous inorganic filler and glass beads, and further mixing a liquid crystalline polyesteramide resin with the mixture. It is not intended. That is, the resin composition of the present invention includes a liquid crystalline polyesteramide resin, a fibrous inorganic filler, and glass beads, and the content ratio of the fibrous inorganic filler and glass beads is within a specific range. Everything is included.

  The content ratio of the fibrous inorganic filler and glass beads contained in the mixture (fibrous inorganic filler: glass beads) is 0.9: 1.0 to 1.0: 0.9. The ratio refers to the mass ratio.

  When the content ratio of the fibrous inorganic filler and the glass beads in the mixture is adjusted to the above range and combined with a liquid crystalline polyesteramide resin to form a resin composition, the formation of blisters can be suppressed. This is because the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer can be reduced by adjusting the content ratio of the fibrous inorganic filler and the glass beads in the mixture to the above range. The present invention focuses on inorganic fillers such as fibrous inorganic fillers and glass beads, and is further characterized in that the content ratio is adjusted to a specific range and the difference in linear expansion coefficient is reduced. . That is, the present invention is characterized in that the difference in the linear expansion coefficient can be reduced by selecting a specific filler and adjusting the content ratio of the specific filler to a specific range.

  Since glass beads are isotropic inorganic fillers, the difference between the coefficient of linear expansion of the core layer and the coefficient of linear expansion of the skin layer is expected to decrease as the glass bead content in the mixture increases. The However, when the content ratio of the fibrous inorganic filler and the glass beads is in the above range close to 1, the difference in the linear expansion coefficient is small. The finding of this point is also one of the features of the present invention.

  “The difference between the linear expansion coefficient of the core layer and the linear expansion coefficient of the skin layer is small” means that the difference in linear expansion coefficient measured by the method described in the examples is 0.7 or less.

  It is preferable to use glass fiber as the fibrous inorganic filler. This is because the combination of glass fiber and glass beads is highly effective in suppressing the generation of blisters. That is, if the combination of glass fiber and glass beads is used, the difference in linear expansion coefficient tends to be small.

  The content of the mixture in the liquid crystalline resin composition for injection molding of the present invention is preferably 39 parts by mass or more and 69 parts by mass or less with respect to 100 parts by mass of the liquid crystalline polyesteramide resin. By containing a sufficient amount of filler in the resin composition of the present invention, sufficient physical properties can be imparted to the molded article.

[Other ingredients]
The liquid crystalline resin composition for injection molding of the present invention may be one obtained by polymer blending with another thermoplastic resin as long as the effects of the present invention are not impaired. Further, two or more thermoplastic resins can be mixed and used. Moreover, in order to improve various properties such as mechanical, electrical, chemical properties and flame retardancy, various additives and reinforcing agents can be added to these resins as necessary.

  In the liquid crystalline resin composition used in the present invention, a filler other than the above-described fillers such as a nucleating agent, a pigment such as carbon black and an inorganic calcined pigment, glass beads, etc., as long as the effects of the present invention are not impaired. Compositions to which desired properties are imparted by adding additives such as antioxidants, stabilizers, plasticizers, lubricants, mold release agents and flame retardants are also included in the liquid crystalline resin composition used in the present invention.

  As described above, other components can be added within a range that does not impair the effects of the present invention, but the content of the other components is within 10 parts by mass with respect to 100 parts by mass of the liquid crystalline polyesteramide resin. It is preferable.

<Molded body>
The molded article of the present invention is a molded article obtained by molding the liquid crystalline resin composition for injection molding of the present invention by an injection molding method. One of the features of the present invention is that the generation of blisters can be suppressed even when molding is performed with a very large injection volume. First, the molding conditions of the molded body will be described, and then the molded body will be described.

[Molding conditions of molded body]
As above-mentioned, the molded object of this invention is a molded object shape | molded using the liquid crystalline resin composition for injection molding of this invention, and molding conditions are not specifically limited. The molding conditions can be appropriately determined according to the shape of the molded body to be produced and the raw materials such as the resin to be used. However, the present invention is characterized in that it can be manufactured under conditions where the injection capacity is large as described above. Thus, hereinafter, the conditions for a large injection capacity will be described.

  Usually, when molding is performed under conditions where the injection capacity is large, blisters tend to occur on the surface of the molded body. However, in the present invention, the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer is reduced to 0. 0 by adding the fibrous inorganic filler and the glass beads to the liquid crystalline polyesteramide resin in a specific ratio. Adjust within 7. As a result, it is possible to suppress the occurrence of blisters that occur on the surface of the molded body even when molded under conditions of a large injection volume. Therefore, according to the present invention, it is possible to manufacture a high-quality molded product with reduced generation of blisters with high productivity.

The “large injection capacity” at which blisters are generated on the surface of the molded body by the conventional technique is 150 cm ³ / sec or more.

The occurrence of blisters, which is a problem in the present invention, has a problem with the flow rate of the molten resin composition flowing in the mold. Increasing the injection capacity also increases the flow rate of the molten resin composition in the mold. If the flow rate of the resin composition flowing in the mold exceeds 7000 mm / sec, the conventional technology tends to cause blisters on the surface of the molded body, and the flow rate of the resin composition flowing in the mold is 12000 mm / sec. When it exceeds, it will become easy to produce a blister on the surface of a molded object. Usually, setting the injection capacity to 150 cm ³ / sec or more means that the flow velocity exceeds at least 7000 mm / sec. As described above, the molded article of the present invention contains a fibrous inorganic filler and glass beads in a specific ratio in a liquid crystalline polyesteramide resin, and the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer is 0. Adjust to within 7. As described above, the difference between the linear expansion coefficient of the core layer and the linear expansion coefficient of the skin layer can be adjusted so that the flow rate of the molten resin composition in the mold increases as described above. The occurrence of blisters on the surface of the molded product can be suppressed.

[Molded body]
As described above, the molded article of the present invention is characterized in that the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer is within 0.7 even when manufactured under the condition of a large injection capacity. . The difference in the linear expansion coefficient can be adjusted by the content ratio between the fibrous inorganic filler and the glass beads.

  The linear expansion coefficient of the core layer and the linear expansion coefficient of the skin layer will be described. The object and method for measuring these linear expansion coefficients will be described. As a test piece for measuring the linear expansion coefficient, a test piece manufactured based on ISO 1/32 '' is used. FIG. 1 shows a cross-sectional view of the test piece. The surface is a skin layer and the inside is a core layer. In the measurement of the linear expansion coefficient of the skin layer, a sample is cut out by cutting a range of 0.2 mm (the range shown in FIG. 1) from the surface of the skin layer. In the measurement of the linear expansion coefficient of the core layer, a sample having a width of 0.2 mm at the center of the core layer (range shown in FIG. 1) is cut out. For these samples heat treated at 250 ° C. for 1 hour, the coefficient of expansion at 240 ° C. when the dimension at 30 ° C. is taken as a reference value is taken as the linear expansion coefficient.

  When a molded product is produced by molding the liquid crystalline resin composition for injection molding of the present invention, the linear expansion coefficient of the core layer and the skin layer line measured as described above are obtained even if the molded article is manufactured under a condition where the injection capacity is large. Since the difference from the expansion coefficient is 0.7 or less, no blister is generated.

  When a conventionally known resin composition is used and a molded body is produced under conditions of a large injection capacity, the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer increases, and blisters are generated. However, by using the resin composition of the present invention, it is possible to suppress an increase in the difference in linear expansion coefficient even when the injection capacity is set to a large condition. As a result, the occurrence of blisters can be suppressed even when the molded body is produced under conditions where the injection capacity is large.

<Method to improve blister resistance>
The method for improving the blister resistance of the present invention includes a fibrous inorganic filler and glass beads in a liquid crystalline resin composition containing a liquid crystalline polyesteramide resin, the content of the fibrous inorganic filler, In this method, the blister resistance of the resin molded product is improved by making the content of the glass beads substantially equal.

  “Substantially equal” means the content of the fibrous inorganic filler in the resin composition so that the difference between the linear expansion coefficient of the core layer and the linear expansion coefficient of the skin layer is 0.7 or less. It refers to bringing the glass bead content closer.

  One of the major features of the present invention is that the fibrous inorganic filler (especially glass fiber) and glass beads are contained in a liquid crystalline polyesteramide resin, and the content ratio (mass ratio) of the fibrous inorganic filler and glass beads. ) Is close to 1, even when a molded body is produced under a condition where the injection capacity is large, the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer does not increase. According to the method of the present invention, a high-quality molded product can be produced with high productivity.

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

<Material>
Liquid crystalline polyesteramide resin (liquid crystalline resin): Vectra E950i (manufactured by Polyplastics) Melt viscosity 20 Pa · sec chopped strand glass fiber (glass fiber): ECS03T-786H (manufactured by Nippon Electric Glass), fiber diameter 10 μm, fiber 3 mm in length (in addition, the result measured by the above-mentioned method about the fiber length in a kneaded pellet was shown in Table 1) Glass beads: EGB731 (made by Potters Barotini), average particle diameter of 18 μm

  After dry blending the materials shown above in the proportions shown in Table 1, kneaded pellets were prepared using a twin screw extruder (“TEX30α type” manufactured by Nippon Steel Works). Using the liquid crystalline resin compositions (kneaded pellets) of Examples and Comparative Examples, measurement of deflection temperature under load, measurement of coefficient of linear expansion, and measurement of blister injection resistance were performed as follows.

[Measurement of deflection temperature under load]
Using test pellets (4 mm × 10 mm × 80 mm) under the following molding conditions, using the kneaded pellets and injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., “SE100DU (screw diameter Φ36)”) of Examples and Comparative Examples. Molded. Thereafter, the deflection temperature under load was measured by a method based on ISO 75-1,2. Table 1 shows the measurement results of the deflection temperature under load. (Molding conditions) Cylinder temperature: 350 ° C. Mold temperature: 90 ° C. Back pressure: 1.0 MPa Injection speed: 33 m / sec

[Measurement of linear expansion coefficient]
Using the kneaded pellets and the injection molding machine (manufactured by FANUC, “ROBOSHOT α50C molding machine (screw diameter Φ26)”) of Examples and Comparative Examples, ISO 1/32 ”combustion test pieces were molded under the following molding conditions. Molding conditions) Cylinder temperature: 340 ° C Mold temperature: 80 ° C Injection speed: 300mm / sec

  A 0.2 mm portion and a central 0.2 mm portion of the obtained test piece were cut from the surface, and a sample was taken out. The linear expansion coefficient of each sample obtained by cutting was measured using a linear expansion measuring instrument (TMA2940) manufactured by TA Instruments. A sample subjected to heat treatment at 250 ° C. for 1 hour was used, and an expansion coefficient at 240 ° C. when a dimension at 30 ° C. was used as a reference value was defined as a linear expansion coefficient. The results of the difference between the linear expansion coefficient and the linear expansion coefficient (linear expansion coefficient of the skin layer−linear expansion coefficient of the core layer) are shown in Table 1.

[Measurement of blister resistance]
Using the kneaded pellets of the example, an injection molding machine (“α-50-C” manufactured by FANUC), ISO 1/32 ″ combustion test pieces were molded. At that time, the nozzle outlet diameter is fixed to 1.5 mm, the ratio of the sprue outlet diameter to the nozzle outlet diameter (sprue outlet diameter / nozzle outlet diameter) is 2, and the other molding conditions are the molding conditions shown below. Went. The position of the nozzle and the position of the sprue are as shown in FIG. Further, as shown in FIG. 2, the nozzle outlet diameter is the nozzle inner diameter of the nozzle tip outlet, and the sprue outlet diameter is the inner diameter of the sprue tip outlet. Also, the injection ^{volume, 26.5 (cm 3 /sec),39.8(cm 3 /sec),53.1(cm} 3 /sec),66.3(cm 3 / sec) 79.6 ( ^{cm 3 /sec),92.9(cm 3 /sec),106.1(cm 3 /sec),119.4(cm 3} /sec),132.7(cm 3 /sec)145.9(cm ³ / sec), 159.2 (cm ³ / sec), and after molding five shots for each injection capacity in order from the lowest, reflow treatment at a peak temperature of 280 ° C. (detailed conditions will be described later) If no blisters can be confirmed by visual observation among 5 molded products, 5 shots are molded under a larger injection capacity, and the same reflow treatment is performed. Until it occurs The maximum injection capacity (blister resistant injection capacity) where blisters were not generated (not observed at all) was determined by visual evaluation.
(Molding condition)
Screw diameter: φ26mm
Screw rotation speed: 100rpm
Back pressure: 3MPa
Holding pressure: 50 MPa
Holding time: 1 second Cooling time: 5 seconds Suckback: 3 mm
Cycle time: 15 seconds Cylinder temperature: 340 ° C-340 ° C-330 ° C-320 ° C
Mold temperature: 80 ℃
(Reflow conditions)
Equipment: Infrared reflow furnace ("RE-300", manufactured by Nippon Pulse Technology Laboratories)
Preheat zone temperature setting: 150 ° C. × 3 minutes Heat zone temperature setting: 218 ° C. × 2 minutes Heating furnace passage time: 5 minutes Molded product surface peak temperature: 280 ° C.
(The peak temperature of the molded product is the highest temperature measured by attaching a thermocouple to the molded product surface under reflow heating conditions.)

As is apparent from Table 1, when the glass fiber content and the glass bead content are the same, the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer is 0.7 or less, and The blister injection capacity exceeds 150 cm ³ / sec.

  As is apparent from the results of Example 2 and Comparative Example 3, Example 2 in which the content of glass beads and the content of glass fiber are the same is higher in Comparative Example 3 than in Comparative Example 3 in which the content of glass beads is large. The difference between the linear expansion coefficient and the linear expansion coefficient of the skin layer was reduced.

Claims (7)

Including a mixture of liquid crystalline polyesteramide resin, fibrous inorganic filler and glass beads,
A ratio of the fibrous inorganic filler to the glass beads in the mixture is 0.9: 1.0 to 1.0: 0.9, for injection molding at an injection capacity of 150 cm ³ / sec or more. Liquid crystalline resin composition for injection molding.   The liquid crystalline resin composition for injection molding according to claim 1, wherein the fibrous inorganic filler is a glass fiber.   The liquid crystalline resin composition for injection molding according to claim 1 or 2, wherein a fiber length of the fibrous inorganic filler is 200 µm or more.   The liquid crystalline resin composition for injection molding according to any one of claims 1 to 3, comprising 39 parts by mass or more and 69 parts by mass or less of the mixture with respect to 100 parts by mass of the liquid crystalline polyesteramide resin. 5. An expansion coefficient at 240 ° C. when the liquid crystalline resin composition for injection molding according to any one of claims 1 to 4 is injection molded at an injection capacity of 150 cm ³ / sec or more and a dimension at 30 ° C. is used as a reference value. Is a molded body in which the difference between the linear expansion coefficient of the skin layer and the linear expansion coefficient of the core layer is 0.7 or less. The melting point of the liquid crystalline polyesteramide resin is 320 ° C. or higher,
The molded article according to claim 5, wherein a deflection temperature under load at 1.8 MPa measured by a method according to ISO 75-1 or 2 is 260 ° C or higher. In the liquid crystalline resin composition, a fibrous inorganic filler and glass beads are included,
A method for improving the blister resistance of a resin molded article by making the content of the fibrous inorganic filler and the content of the glass beads substantially the same.

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