JP5642947B2 - Manufacturing method of injection molded products - Google Patents

Description

  The present invention relates to a method for producing an injection molded product using a liquid crystalline resin composition.

  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 a crystal structure. High strength based on this crystal structure is one of the characteristics of the liquid crystalline resin. Furthermore, the liquid crystalline resin has a small volume change between melting and solidification because the crystal structure does not change greatly upon solidification. As a result, the liquid crystalline resin has an advantage that the molding shrinkage is small and the dimensional accuracy of the molded product is excellent.

  Taking advantage of the above-described advantages such as high strength and excellent dimensional accuracy, the liquid crystalline resin composition is used for precision instrument parts. By the way, in the case of precision equipment and optical equipment, a small amount of dust, dust, etc. affect the equipment performance. For this reason, components used in precision instruments and optical instruments, such as camera module parts, are usually ultrasonically cleaned using water or the like to remove small dust, oil, dust, etc. adhering to the surface of the parts. . However, a molded product formed by molding the liquid crystalline resin composition is relatively easily fibrillated on the surface because the molecular orientation is particularly large in the surface portion. For this reason, if the surface of a molded product peels, it will become a factor of dropout (dust). Therefore, since generation | occurrence | production of dust etc. becomes a problem, it is very difficult to ultrasonically wash the molded product formed by shape | molding a liquid crystalline resin composition.

  The generation of dust and the like occurs because the molecular orientation is particularly large on the surface of the molded product as described above. Therefore, as a resin molded body with improved surface characteristics, it is a resin molded product containing a liquid crystalline polymer and a fibrous filler, and the increase in the surface roughness Ra value obtained by a specific surface tape peeling test is 0. A resin molded product characterized by having a flat portion of 4 μm or less is disclosed (Patent Document 1).

  According to the method described in Patent Document 1, it is useful as a component of an electric / electronic device or an optical device, and can prevent the generation of surface particles (foreign matter). Thus, when the technique described in Patent Document 1 is used, the surface characteristics can be improved.

  However, as described in the Examples of Patent Document 1, the generation of foreign matter in Patent Document 1 is a foreign matter that occurs when the surface is washed by gently stirring in pure water for 1 minute. Therefore, in the improvement of the surface characteristics by the method described in Patent Document 1, a satisfactory result cannot be obtained for the suppression of fibrillation during ultrasonic cleaning. That is, in the method described in Patent Document 1, when a resin molded product is exposed to severe conditions such as ultrasonic cleaning, a large amount of foreign matter is generated.

  Moreover, in patent document 1, in order to suppress generation | occurrence | production of the said dust etc., the one where the mold temperature at the time of shaping | molding is higher is preferable. Actually, in the example of Patent Document 1, molding is performed under the condition of a mold temperature of 130 ° C. When the mold temperature condition is set to a temperature exceeding 100 ° C., the temperature cannot be adjusted with water, and the temperature must be adjusted using oil. For this reason, from the viewpoint of facilitating the production of injection-molded products, it is required to mold the mold at a temperature of 100 ° C. or less.

  Furthermore, since the injection-molded product has a particularly large molecular orientation at the surface portion, surface fibrillation is likely to occur and ultrasonic cleaning or the like tends to cause fluff. For this reason, there is a demand for a technique for improving surface characteristics that can be applied to injection molded products.

  In addition, the above-described surface fluffing and the above-described peeling of the molded product surface impair the appearance of the injection-molded product. For this reason, the injection molded product formed by injection molding the liquid crystalline resin composition is also required to have an excellent appearance.

JP 2008-239950 A

  The present invention has been made to solve the above-described problems, and its purpose is to suppress the fibrillation of the surface of an injection-molded product even when the liquid crystalline resin composition is subjected to ultrasonic cleaning, and has an excellent appearance. It is providing the shaping | molding technique for obtaining the molded article which has. In particular, an object of the present invention is to provide a molding technique that can be carried out even when the mold temperature is 100 ° C. or less.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, in the injection molding of the liquid crystalline resin composition, a mold in which a heat insulating layer is formed on the inner surface of the mold is used, the heat insulating layer thickness t1, the injection speed S, the injection molded product thickness t2, the mold temperature T. In this case, the present inventors have found that the above problems can be solved by injection molding under molding conditions that satisfy a specific relational expression, and have completed the present invention. Specifically, the present invention provides the following.

(1) In the injection molding of a liquid crystalline resin composition, a mold having a heat insulating layer formed on the inner surface of the mold is used, the thickness t1 (μm) of the heat insulating layer, the injection speed S (mm / sec), and the injection molded product. The manufacturing method of the injection molded product which carries out injection molding on the molding conditions which satisfy | fill following formula (I), when it is set as thickness t2 (mm) of this and mold temperature T (degreeC).

(2) The method for producing an injection molded product according to (1), wherein the injection molding is performed under molding conditions satisfying the following formula (II).

  (3) The said heat insulation layer is a manufacturing method of the injection molded product as described in (1) or (2) whose heat conductivity is 5 W / m * K or less.

  (4) The said heat insulation layer is a manufacturing method of the injection molded product in any one of (1) to (3) containing a polyimide resin.

  (5) The method for producing an injection-molded article according to any one of (1) to (4), wherein a mold temperature T is 100 ° C. or lower.

  The injection-molded product obtained by the production method of the present invention does not generate dropouts (dust) due to peeling of the surface of the molded product even by ultrasonic cleaning. For this reason, the injection molded product used for the precision instrument, the optical instrument, etc. manufactured by the manufacturing method of the present invention can be easily ultrasonically cleaned, and the cleaning operation at the time of manufacturing the parts can be performed efficiently. .

  The injection molded product obtained by the production method of the present invention has an excellent appearance. In particular, since the surface of an injection molded product obtained by the production method of the present invention is not easily peeled off, it is easy to maintain a beautiful appearance for a long period of time.

  The production method of the present invention can be performed under conditions where the mold temperature is 100 ° C. or lower. For this reason, the temperature adjustment of the metal mold | die at the time of obtaining an injection molded product can be performed with water instead of oil. As a result, an excellent injection molded product can be easily obtained.

It is a figure which shows the multilayer structure of the injection molded product obtained by the manufacturing method of this invention. It is a figure which shows the multilayer structure of the injection molded product obtained by the manufacturing method of a prior art. It is a figure which shows the multilayer structure of the injection molded product manufactured on the conditions which satisfy | fill following formula (II).

  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.

  In the injection molding of the liquid crystalline resin composition, the present invention uses a mold in which a heat insulating layer is formed on the inner surface of the mold, and the thickness t1 (μm) of the heat insulating layer, the injection speed S (mm / sec), When the thickness t2 (mm) of the injection-molded product and the mold temperature T (° C.) are used, injection molding is performed under molding conditions that satisfy a specific relational expression. Hereinafter, the present invention will be described in the order of a liquid crystalline resin composition and a method for producing an injection molded product.

<Liquid crystal resin composition>
The method for producing an injection-molded article of the present invention can be applied to all liquid crystalline resin compositions containing a liquid crystalline resin.

[Liquid crystal resin]
The liquid crystalline resin 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 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 resin as described above is not particularly limited, but is preferably an aromatic polyester or an aromatic polyester amide, and a polyester partially including an aromatic polyester or an aromatic polyester amide in the same molecular chain is also within the range. It is in. 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 resin applicable to the present invention is particularly preferably at least one compound selected from the group of aromatic hydroxycarboxylic acids, aromatic hydroxyamines, and aromatic diamines. Aromatic polyesters and aromatic polyester amides as constituent components.

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 of aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more of aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). A polyester amide comprising one or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof;
(4) mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more of 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 And polyester amides composed of Furthermore, you may use a molecular weight modifier together with said structural component as needed.

（Ｘ：アルキレン（Ｃ１〜Ｃ４）、アルキリデン、−Ｏ−、−ＳＯ−、−ＳＯ_２−、−Ｓ−、−ＣＯ−より選ばれる基である）

（Ｙ：−（ＣＨ_２）_ｎ−（ｎ＝１〜４）、−Ｏ（ＣＨ_２）_ｎＯ−（ｎ＝１〜４）より選ばれる基である。） Preferable examples of specific compounds constituting the liquid crystalline resin applicable to the present invention include p-hydroxybenzoic acid, aromatic hydroxycarboxylic acids such as 6-hydroxy-2-naphthoic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, aromatic diols such as compounds represented by the following general formula (A) and the following general formula (B); terephthalic acid, isophthalic acid, 4 , 4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and aromatic dicarboxylic acids such as compounds represented by the following general formula (C); aromatic amines such as p-aminophenol and p-phenylenediamine Can be mentioned.

(X: alkylene (C1 -C4), _{alkylidene, -O -, - SO -,} - SO 2 -, - S -, - is a group selected from CO-)

(Y is a group selected from — (CH ₂ ) _n — (n = 1 to 4) and —O (CH ₂ ) _n O— (n = 1 to 4).

[Other ingredients]
The liquid crystalline resin composition used in the present invention includes other resins, nucleating agents, carbon black, inorganic baked pigments and other pigments, antioxidants, stabilizers, plasticizers, and lubricants as long as the effects of the present invention are not impaired. The liquid crystal resin composition used in the present invention also includes a composition imparted with desired characteristics by adding additives such as a release agent and a flame retardant.

<Manufacturing method of injection molded product>
The method for producing an injection-molded article of the present invention uses a mold in which a heat insulating layer is formed on the inner surface of the mold in the injection molding of the liquid crystalline resin composition, the thickness t1 (μm) of the heat insulating layer, and the injection speed S. (Mm / sec), injection molded product thickness t2 (mm), and mold temperature T (° C.), injection molding is performed under molding conditions that satisfy the following relational expression (I).

[Mold]
In the method for producing an injection-molded article of the present invention, a mold in which a heat insulating layer is formed on the inner surface of the mold (the inner surface of the mold) is used. The heat-insulating layer formed on the inner surface of the mold makes it difficult for the liquid crystalline resin composition that has flowed into the mold to harden in the vicinity of the mold surface. As a result, it is possible to prevent molecules contained in the resin composition before solidification coming into contact with the resin composition solidified on the mold surface from being pulled by the resin composition after solidification and increasing molecular orientation on the surface of the molded product. Can do.

  The heat insulation layer formed on the inner surface of the mold is not particularly limited as long as it functions to delay solidification of the liquid crystalline resin composition on the mold surface. In addition, those having a heat insulating layer formed on a part of the inner surface of the mold are also included in the “mold having the heat insulating layer formed on the inner surface of the mold”. In the method for producing an injection-molded product of the present invention, it is necessary to form at least all of the desired inner surface portion of the mold corresponding to the portion that requires good appearance characteristics in the obtained molded product. It is preferable to form on the entire inner surface.

  The thickness (t1) of the heat insulating layer is not particularly limited as long as it is adjusted to satisfy the above formula (I) as described later. The thickness of the heat insulating layer formed on the inner surface of the mold may be uniform or may include portions having different thicknesses. When the thickness of the heat insulation layer is not uniform, the average thickness is set to t1.

  Further, the heat conductivity of the heat insulating layer formed on the inner surface of the mold is particularly preferably 5 W / m · K or less. By adjusting the thermal conductivity of the heat-insulating layer to the above range, even if an injection molded product is molded at a mold temperature of 100 ° C. or less, the surface of the molded product does not peel off when ultrasonic cleaning is performed. It becomes easier to obtain an injection-molded product having a good appearance. In addition, the said heat conductivity points out the heat conductivity measured by the method as described in an Example.

  Further, since a high-temperature liquid crystalline resin composition flows into the mold during injection molding, the heat insulating layer needs to have heat resistance that can withstand the high temperature during molding.

  The heat insulating layer formed on the inner surface of the mold used in the method for producing an injection molded product of the present invention preferably contains a polyimide resin. This is because the polyimide resin has a thermal conductivity of 5 W / m · K or less, and has heat resistance enough to withstand high temperatures during injection molding. Specific examples of polyimide resins that can be used include pyromellitic acid (PMDA) -based polyimide, biphenyltetracarboxylic acid-based polyimide, polyamideimide using trimellitic acid, bismaleimide-based resins (bismaleimide / triazine-based, etc.), benzophenone Examples include tetracarboxylic acid-based polyimides, acetylene-terminated polyimides, and thermoplastic polyimides. In particular, a heat insulating layer made of a polyimide resin is preferable. Preferable materials other than polyimide resin include, for example, tetrafluoroethylene resin.

  The method for forming the heat insulating layer on the inner surface of the mold is not particularly limited. For example, it is preferable to form the heat insulating layer on the inner surface of the mold by the following method.

  A solution of a polymer precursor such as a polyimide precursor capable of forming a polymer heat insulating layer is applied to the mold surface, heated to evaporate the solvent, and further heated to polymerize to form a heat insulating layer such as a polyimide film. For forming, heat-resistant polymer monomers, for example, pyromellitic anhydride and 4,4-diaminodiphenyl ether are vapor-deposited, or for planar molds, a polymer heat insulating film is used as an appropriate bonding method Or the method of sticking on the desired part of a metal mold | die using an adhesive tape-shaped polymer heat insulation film, and forming a heat insulation layer is mentioned. It is also possible to form a polyimide film and further form a chromium (Cr) film or a titanium nitride (TiN) film as a metal-based hard film on the surface thereof.

[Molding condition]
The manufacturing method of the injection molded product of the present invention is the case where the thickness t1 (μm) of the heat insulation layer, the injection speed S (mm / sec), the thickness t2 (mm) of the injection molded product, and the mold temperature T (° C.). The injection molding is performed under molding conditions that satisfy the relational expression of the following formula (I).

  By producing an injection molded product under the above conditions, the boundary between the surface layer and the skin layer does not exist on at least a part of the surface of the molded product as will be described later. The peeling of the surface of the injection molded product is caused by peeling of the surface layer formed further on the skin layer. In the present invention, this surface layer is obtained as an injection molded product having no surface layer on at least a part of the surface of the molded product. It is done. As a result, it is possible to obtain a high-quality injection-molded product that has an excellent appearance and does not peel off even when ultrasonically cleaned.

  The injection molded product obtained by the production method of the present invention is characterized in that at least part of the boundary between the surface layer and the skin layer on the surface of the molded product is eliminated. As a result of obtaining such an injection molded product, the effect of suppressing surface peeling of the injection molded product is remarkably enhanced. As described above, the injection molded product having an excellent appearance with very little peeling on the surface of the molded product prevents the liquid crystalline resin composition flowing into the mold from immediately solidifying on the mold surface, and solidifies the resin composition. Thus, it is presumed that it is obtained by suppressing the molecules of the resin composition portion before solidification from being pulled and the molecular orientation from becoming large on the surface of the molded product.

  As described above, the heat insulating layer has a function of suppressing the resin composition from immediately solidifying on the mold surface when the molten liquid crystalline resin composition flows into the mold.

  By improving the injection speed, the time for filling the resin composition in the mold is shortened. That is, the filling of the liquid crystal resin composition into the mold can be finished at a stage where the solidification of the liquid crystal resin composition does not proceed excessively. As a result, it can be suppressed that the molecules before solidification are pulled by the solidified resin composition and the molecular orientation is increased on the surface of the molded product.

  If the thickness of the injection molded product is too thick, it takes time to fill the liquid crystalline resin composition in the mold. For this reason, if the thickness of the injection-molded product is too thick, the solidified resin composition tends to cause a phenomenon in which molecules in the portion before solidification are pulled and molecular orientation is increased on the surface of the molded product.

  By setting the mold temperature T high, solidification of the liquid crystalline resin composition in the vicinity of the inner surface of the mold can be particularly delayed. As a result, it is possible to suppress a phenomenon in which molecules before solidification are pulled by the solidified resin composition and molecular orientation is increased on the surface of the molded product.

  The feature of the present invention is that the heat insulating layer thickness t1 (μm), the injection speed S (mm / sec), the mold temperature T (° C.), and the injection molded product thickness t2 (mm) satisfy the above formula (I). It is found that the boundary between the surface layer and the skin layer on the surface of the injection molded product is eliminated by adjusting to.

  In the present invention, by adjusting the injection speed S (mm / sec), the heat insulating layer thickness t1 (μm), and the mold temperature T (° C.), various shapes (particularly even when t2 (mm) is thick). Can be manufactured. This is because the boundary between the surface layer and the skin layer of the injection-molded product does not exist at least in part as long as the above formula (I) is satisfied.

Moreover, by performing injection molding under molding conditions satisfying the following formula (II), surface peeling is less likely to occur, and an injection molded product having an extremely excellent appearance can be obtained. Specifically, by performing injection molding under the condition satisfying the following formula (II), a molded product having no boundary between the surface layer and the skin layer can be easily obtained. Hereinafter, the manufacturing conditions of the manufacturing method of this invention are demonstrated in detail.

  First, the heat insulating layer thickness t1 (μm) will be described. Heat insulation layer thickness t1 should just be adjusted so that the said Formula (I) may be satisfy | filled, and the thickness is not specifically limited. In the production method of the present invention, it is preferable to adjust the heat insulating layer thickness t1 from 1 μm to 1000 μm, although it varies depending on the type of liquid crystalline resin composition used, the shape of the injection molded product, and the like. Adjusting the thickness of the heat insulating layer to 1 μm or more is preferable because a sufficient heat insulating effect can be obtained, and adjusting to 1000 μm or less is preferable for the accuracy of the molded product. A more preferable heat insulating layer thickness t1 is 10 μm to 300 μm.

  Next, the injection speed S (mm / sec) will be described. The injection speed S may be adjusted so as to satisfy the above formula (I) similarly to the heat insulating layer thickness t1. In the production method of the present invention, it is preferable to adjust the injection speed S in the range of 20 mm / sec to 1000 mm / sec, although it varies depending on the type of liquid crystalline resin composition used and the shape of the injection molded product. Adjusting the injection speed to 20 mm / sec or more is preferable because hesitation can be prevented, and adjusting the injection speed to 1000 mm / sec or less is preferable because jetting can be prevented. A more preferable injection speed is 50 mm / sec to 500 mm / sec.

  Next, the mold temperature T (° C.) will be described. The mold temperature T may be adjusted so as to satisfy the above formula (I) similarly to the heat insulating layer thickness t1 and the like. In the production method of the present invention, the mold temperature T is preferably adjusted to 100 ° C. or lower, although it varies depending on the type of liquid crystalline resin composition to be used, the shape of the injection molded product, and the like. By setting the mold temperature T to 100 ° C. or lower, the mold temperature can be adjusted with water, and a high-quality injection-molded product can be easily obtained. A more preferable mold temperature range is 50 ° C to 100 ° C.

  By adjusting the heat insulating layer thickness t1, the injection speed S, and the mold temperature T, the injection molded product thickness t2 can be adjusted in a wide range. Specifically, the thickness t2 of the injection molded product can be adjusted from 0.2 mm to 10 mm under the condition satisfying the above formula (I). Under the condition satisfying the above formula (II), t2 can be adjusted from 0.2 mm to 5 mm. In particular, when the thickness t2 of the injection-molded product is in the range of 0.2 mm to 3 mm, the above-mentioned problem is likely to occur. However, by molding according to the production method of the present invention, there is no surface peeling and a high-quality injection-molded product having an excellent appearance. Can be easily obtained.

[Injection molded products]
When the liquid crystalline resin composition is molded, a multilayer structure is obtained. FIG. 1 shows a multilayer structure (from a central portion to a surface portion) of an injection molded product obtained by the production method of the present invention. As shown to Fig.1 (a), the injection molded product obtained by the manufacturing method of this invention does not have the boundary of a surface layer and a skin layer in at least one part of the molded product surface. Therefore, even if the injection molded product obtained by the manufacturing method of the present invention is subjected to ultrasonic cleaning or the like, the portion where surface peeling occurs is reduced as shown in FIG.

  On the other hand, FIG. 2 shows a multilayer structure (from the central part to the surface part) of the injection molded product obtained by the manufacturing method of the prior art. As shown in FIG. 2A, a surface layer is present on the entire surface of the injection molded product. Therefore, when ultrasonic cleaning or the like is performed on an injection molded product obtained by the manufacturing method of the prior art, surface peeling occurs on the entire surface as shown in FIG.

  FIG. 3 shows a multilayer structure (from the center portion to the surface portion) of the injection molded product manufactured under the condition satisfying the above formula (II). As shown in FIG. 3, among the injection molded products obtained by the manufacturing method of the present invention, the injection molded products manufactured under the conditions satisfying the above formula (II) tend to have no boundary between the surface layer and the skin layer. . Therefore, even if ultrasonic cleaning or the like is performed, it becomes an injection molded product that hardly causes surface peeling.

  As described above, the injection-molded product obtained by the production method of the present invention does not peel off even when subjected to ultrasonic cleaning, and has an excellent appearance. Furthermore, by setting the mold temperature to 100 ° C. or less, a high-quality injection molded product can be easily obtained.

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

<Material>
Liquid crystalline resin 1: “Vectra (registered trademark) E130i” Glass fiber 30% by mass Filling material Melting point 335 ° C., melt viscosity 40 Pa · s (manufactured by Polyplastics Co., Ltd.)
Heat insulation layer forming material 1: polyimide resin tape (manufactured by Sumitomo 3M), thermal conductivity 0.2 W / m · K
Thermal insulation layer forming material 2: polyimide resin varnish (Fine Chemical Japan), thermal conductivity 0.2 W / m · K
Heat insulation layer forming material 3: polyimide resin film (manufactured by Toray DuPont), thermal conductivity 0.2 W / m · K

  The thermal conductivity of the polyimide resin was calculated by measuring thermal diffusivity by laser flash method, specific gravity by Archimedes method, and specific heat by DSC.

<Example 1>
Using the liquid crystalline resin 1 as a molding material, the heat insulating layer forming material 1 is affixed to the mold cavity surface of a flat plate molding mold having a width of 20 mm, a length of 50 mm, and a thickness of 0.5 mm. Molding was performed under molding conditions such as injection speed and mold temperature to obtain an injection molded product. The conditions other than the molding conditions shown in the table are as follows.
[Molding condition]
Cylinder set temperature: 350 ° C
Screw rotation speed: 150rpm

<Example 2>
After using the liquid crystalline resin 1 as a molding material and spraying the heat insulation layer forming material 2 on the mold cavity surface of a plate molding mold of 40 mm □ × thickness 1 mm and baking at 250 ° C. for 1 hour, After the polyimide surface was polished and adjusted to the thickness of the heat insulating layer in Table 1, molding was performed at the injection speed and mold temperature in Table 1 to obtain an injection molded product. The molding conditions other than those shown in Table 1 are the same as in Example 1.

<Example 3>
An injection molded product was produced in the same manner as in Example 2 except that the molding conditions were changed to the conditions shown in Table 1. The molding conditions other than those shown in Table 1 are the same as in Example 1.

<Example 4>
A liquid crystalline resin 1 is used as a molding material, and a heat insulating layer forming material 3 is affixed to a mold cavity surface of an ISO standard test piece mold with double-sided tape, and the injection speed and mold temperature shown in Table 1 are used. Molding was performed to obtain an injection molded product. The molding conditions other than those shown in Table 1 are the same as in Example 1.

<Example 5>
An injection molded product was produced in the same manner as in Example 4 except that the molding conditions were changed to the conditions shown in Table 1. The molding conditions other than those shown in Table 1 are the same as in Example 1.

<Comparative Example 1>
An injection molded product was produced in the same manner as in Example 4 except that the molding conditions were changed to the conditions shown in Table 1. The molding conditions other than those shown in Table 1 are the same as in Example 1.

<Comparative example 2>
An injection molded article was produced in the same manner as in Example 1 except that the heat insulating layer was not formed in the mold.

<Comparative Example 3>
An injection molded product was produced in the same manner as in Comparative Example 2 except that the molding conditions were changed to the conditions shown in Table 1. The molding conditions other than those shown in Table 1 are the same as in Example 1.

<Evaluation of molded products>
The cross-cut test evaluation and the ultrasonic cleaning test evaluation were performed on the injection molded products of Examples and Comparative Examples.

[Cross-cut test evaluation]
Evaluation was performed by a method according to JIS K5400, and the evaluation was performed using the number of peeled lattices out of 100 lattices of 1 mm □. The evaluation results are shown in Table 1.

[Ultrasonic cleaning test]
The injection-molded articles of Examples and Comparative Examples were immersed in water, subjected to ultrasonic cleaning for 1 minute, the surface fibril generation state was measured as a surface whitening phenomenon, and the presence or absence of fibril generation was evaluated. The evaluation results are shown in Table 1.

  As is apparent from Table 1, the injection molded product obtained by the production method of the present invention was found to be less susceptible to surface peeling, as is clear from the number of peels in the cross-cut peel test evaluation. As described above, the injection molded product obtained by the production method of the present invention is unlikely to peel off, so that a beautiful appearance can be maintained.

  Further, as is clear from Table 1, in Examples 1 to 3 and 5, it was found that no fibril generation occurred from the ultrasonic cleaning test. In Examples 1 to 3 and 5, it was confirmed that there was no boundary between the surface layer and the skin layer on the surface of the injection molded product. Moreover, although fibril generation on the surface occurred in Example 4, the generation area is very small compared with the generation area of fibrillation generated on the surface of the molded article of the comparative example. Therefore, in Example 4, it was confirmed that a boundary between the surface layer and the skin layer exists in part.

  It was confirmed that the production method of the present invention can produce a high-quality injection-molded product even under a mold temperature of 100 ° C. or less.

  As is clear from the results of Examples 1 to 3, 5 and the result of Example 4, the boundary between the surface layer and the skin layer is obtained by producing an injection molded product under the condition satisfying the above formula (II). It was confirmed that an excellent injection-molded product in which no is present can be obtained.

Claims (4)

In the injection molding of the liquid crystalline resin composition, using a mold having a heat insulating layer formed on the inner surface of the mold,
When the thickness t1 (μm) of the heat insulation layer, the injection speed S (mm / sec), the thickness t2 (mm) of the injection molded product, and the mold temperature T (° C.), the mold temperature T is set to 80 ° C. or more and 100 A method for producing an injection-molded article, which is injection-molded under molding conditions that are not higher than ° C. and satisfy the following formula (I).

The method for producing an injection-molded article according to claim 1, wherein injection molding is performed under molding conditions satisfying the following formula (II).

  The method of manufacturing an injection molded product according to claim 1, wherein the heat insulating layer has a thermal conductivity of 5 W / m · K or less.   The said heat insulation layer is a manufacturing method of the injection molded product in any one of Claim 1 to 3 containing a polyimide resin.

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