JP4932695B2 - Liquid crystalline polymer composition - Google Patents

Description

  The present invention relates to a liquid crystal polymer composition having a small anisotropy of molding shrinkage and good surface smoothness.

  Liquid crystalline polymers that can form an anisotropic melt phase are known as materials with excellent moldability, dimensional stability, and fluidity, and have been widely used in fields that require high dimensional accuracy and thin fillability. .

  However, the liquid crystalline polymer has a problem that the anisotropy of the molding shrinkage rate in the flow direction and the direction perpendicular to the flow is large because of its high anisotropy. For this reason, the mold is designed in consideration of the molding shrinkage. However, if the anisotropy of the molding shrinkage is large, the mold shrinkage varies greatly due to the flow of the resin. It is very difficult to obtain a molded product.

  Therefore, in a molded product that requires a high degree of dimensional accuracy, a composite material with various fillers is generally used in order to reduce anisotropy and improve anisotropy of molding shrinkage (Patent Document 1). 2) These materials have a problem of poor fluidity and reduced surface smoothness.

The larger the average particle size of the filler to be blended, the more the anisotropy of the molding shrinkage ratio is improved. However, the surface smoothness becomes worse, and it is difficult to achieve both properties by controlling the average particle size alone. there were.
Japanese Patent Laid-Open No. 63-162753 JP-A 63-146959

  The object of the present invention is to provide a liquid crystalline polymer composition that solves the disadvantages of the prior art and has a small anisotropy in molding shrinkage and good surface smoothness.

  As a result of diligent research to achieve the above object, the present inventors have specified the type of filler, the amount of filler, the average particle size before melt-kneading, and the average of the filler in the composition to optimize the production conditions. By defining the particle diameter, it was found that a liquid crystalline polymer composition having a small anisotropy of molding shrinkage ratio and good surface smoothness was obtained, and the present invention was completed.

  That is, the present invention was obtained by melting and kneading 80 to 120 parts by weight of glass flakes having an average particle diameter of 150 to 500 μm and an average thickness of 4 to 6 μm with respect to 100 parts by weight of (A) liquid crystalline polymer. This is a liquid crystalline polymer composition in which glass flakes having an average particle diameter of φ80 to 100 μm and an average thickness of 4 to 6 μm are uniformly dispersed in the liquid crystalline polymer.

  Hereinafter, the present invention will be described in detail. The liquid crystalline polymer (A) used in the present invention refers to a melt processable polymer having a property capable of forming an optically anisotropic molten phase. 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 polymer applicable to the present invention is inspected between crossed polarizers, the polarized light is normally transmitted even in the molten stationary state, and optically anisotropic.

  The liquid crystalline polymer (A) is not particularly limited, but is preferably an aromatic polyester or an aromatic polyester amide, and an aromatic polyester or a polyester partially containing the aromatic polyester amide in the same molecular chain. Is also in that range. They preferably have a logarithmic viscosity (IV) of at least about 2.0 dl / g, more preferably 2.0-10.0 dl / g when dissolved in pentafluorophenol at 60 ° C. at a concentration of 0.1% by weight. .) Are used.

  The aromatic polyester or aromatic polyester amide as the liquid crystalline polymer (A) applicable to the present invention is particularly preferably at least one selected from the group consisting of aromatic hydroxycarboxylic acids, aromatic hydroxyamines and aromatic diamines. An aromatic polyester or aromatic polyester amide having the above compound as a constituent component.

More specifically,
(1) A polyester mainly composed of one or more aromatic hydroxycarboxylic acids and derivatives thereof;
(2) mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof; and (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof; c) Polyester comprising at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof;
(3) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). A polyesteramide comprising one or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof;
(4) mainly (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). One or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof; and (d) at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof, and The polyesteramide which consists of, etc. are mentioned. Furthermore, you may use a molecular weight modifier together with said structural component as needed.

  Specific examples of the specific compound constituting the liquid crystalline polymer (A) applicable to the present invention include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, 2,6- Aromatic diols such as dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, hydroquinone, resorcinol, compounds represented by the following general formula (I) and the following general formula (II); terephthalic acid, isophthal Aromatic dicarboxylic acids such as acids, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and compounds represented by the following general formula (III); aromatics such as p-aminophenol and p-phenylenediamine Examples include amines.

(However, X: alkylene (C1 -C4), alkylidene, -O-, -SO -, - SO 2 -, -S -, - CO- than group _{selected, Y :-( CH 2) n -} (n = 1~4), - O (CH 2) n O- (n = 1~4) from the group selected)
Particularly preferred liquid crystalline polymers (A) to which the present invention is applied are aromatic polyesters containing p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid as the main structural unit component.

  The glass flakes of component (B) used in the present invention are required to have an average particle diameter before melt kneading of φ150 to 500 μm and an average thickness of 4 to 6 μm. In order to improve the anisotropy of the molding shrinkage ratio, the average particle size before melt kneading needs to be 150 μm or more, and if the average particle size is larger than 500 μm, there is a thin part in the molded product This is not preferable because it may not be filled.

  The amount of component (B) is 80 to 120 parts by weight per 100 parts by weight of (A) liquid crystalline polymer. When the blending amount is less than 80 parts by weight, the effect of improving the anisotropy of the molding shrinkage is small, and when it exceeds 120 parts by weight, the fluidity is deteriorated, which is not preferable.

  In the present invention, glass flakes having an average particle diameter of φ80 to 100 μm and an average thickness of 4 to 6 μm are uniformly dispersed in the obtained liquid crystalline polymer by melt-kneading the components (A) and (B). It is necessary to be.

  If the average particle size is made smaller than 80 μm by melt-kneading, it is not preferable because a relatively large particle size having a large effect of improving the anisotropy of the molding shrinkage rate is reduced. Further, unless the average particle size is reduced to 100 μm, many particles having large particle sizes that deteriorate the surface smoothness are not preferable. If the surface roughness Ra, which is one of the indices of surface smoothness, is 1.7 (μm) or less, there is no problem in practical use.

  Appropriate melt-kneading conditions may be employed in order to develop the above dispersion state. For example, when the amount of extrusion per time during kneading is Q (kg) and the screw rotation speed is N (rpm), Q What is necessary is just to melt-knead on the conditions from which / N becomes 0.1-1.5.

  When the Q / N is less than 0.1, shear stress is applied for a long time, so that the glass flakes are largely broken, and as a result, it becomes difficult to obtain those having an average particle diameter of φ80 to 100 μm. On the other hand, when Q / N is larger than 1.5, the resin is severely decomposed due to inadequate kneading or shearing heat, which causes a decrease in mechanical strength and deterioration of moldability of the molded product.

  Here, since the upper limit value of the extrusion amount Q differs depending on the screw diameter size of the extruder, the upper limit value of Q increases especially when the screw diameter size increases. Therefore, after setting Q, the value of Q / N is 0.1. It is practically difficult to set the screw rotation speed N so as to be ˜1.5. Therefore, first, it is practical to set the extrusion amount Q so that the screw rotation speed N is set to 50 to 500 (rpm), preferably 100 to 300 (rpm), and the Q / N value is 0.1 to 1.5. Is. By setting the resin temperature during kneading to 300 to 330 ° C. and normal extrusion kneading conditions, the intended resin composition can be obtained.

  Addition of additives such as nucleating agent, carbon black, pigments such as inorganic baked pigments, antioxidants, stabilizers, plasticizers, lubricants, mold release agents and flame retardants to the liquid crystalline polymer composition, Compositions imparted with desired characteristics are also included in the range of the liquid crystalline polymer composition referred to in the present invention.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, the method of the physical property measurement in an Example is as follows.

As a test piece for molding shrinkage measurement and surface roughness measurement, a FANUC Roboshot α-100iA molding machine is used, and a 2mm thick 80 × 80mm flat plate under conditions of a cylinder temperature of 300 ° C and a mold temperature of 80 ° C. Was molded. As a specimen for an ISO bending test, a Nikko J75SSII-A molding machine was used, and molding was performed under conditions of a cylinder temperature of 300 ° C. and a mold temperature of 90 ° C.
[Melt viscosity]
The apparent melt viscosity was measured according to ISO 11443 using a capillary rheometer (Capillograph 1B manufactured by Toyo Seiki Co., Ltd., piston diameter: 10 mm) at a temperature of 300 ° C. and a shear rate of 1000 sec ⁻¹ . For the measurement, an orifice having an inner diameter of 1 mm and a length of 20 mm was used.
[Flake diameter]
Ash was collected by heating the obtained pellets at 600 ° C. for 3 hours, and measured using a particle size distribution measuring device (manufactured by Horiba, Ltd., particle size distribution measuring device LA-920) using pure water as a dispersion medium.
[Mold shrinkage]
Using a three-dimensional measuring device (manufactured by Mitutoyo, three-dimensional dimension measuring device FN704), the range shown in FIG. 1 was measured as a flow direction a and a flow right-angle direction b.
[Surface roughness Ra]
A surface roughness measuring device (manufactured by Mitutoyo Co., Ltd., contour shape measuring device Surf Test SV-C624) was used to measure the range in the flow perpendicular direction 15 mm at the center of the flat plate as shown in FIG.

Examples 1-2 and Comparative Examples 1-3
100 parts by weight of a liquid crystalline polymer (Vectra A950, manufactured by Polyplastics Co., Ltd.), 100 parts by weight of glass flakes (REF-160, manufactured by Nippon Sheet Glass Co., Ltd.) having an average particle diameter of 160 μm and an average thickness of 5 μm, and pentaerythritol stearate After dry blending 0.3 parts by weight, the mixture was kneaded using a twin-screw extruder (TEX30α type, manufactured by Nippon Steel) under the extrusion conditions of extrusion amount Q and screw rotation speed N shown in Table 1 to obtain pellets.
Using this pellet, a test piece was prepared and evaluated as described above.

Comparative Example 4
The pellets obtained in Example 1 and the liquid crystalline polymer (Vectra A950 manufactured by Polyplastics Co., Ltd.) were dried at a ratio of 30% by weight of glass flakes (43 parts by weight of glass flakes per 100 parts by weight of liquid crystalline polymer). After blending, test pieces were prepared and evaluated using an injection molding machine.

It is a figure which shows the measurement condition of the molding shrinkage rate in an Example. The unit of the numerical values in the figure is mm. It is a figure which shows the measurement condition of the surface roughness in an Example. The unit of the numerical values in the figure is mm.

Claims (1)

(A) In 100 parts by weight of a liquid crystalline polymer, (B) 80 to 120 parts by weight of glass flakes having an average particle diameter of φ150 to 500 μm and an average thickness of 4 to 6 μm were melt-kneaded. A liquid crystalline polymer composition in which glass flakes having an average particle diameter of φ80 to 100 μm and an average thickness of 4 to 6 μm are uniformly dispersed.

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