JP2007296769A - Insert molding method and heat-resistant resin member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert molding method to be used for the manufacture of a heat-resistant resin member and can easily and securely fill a narrow gap part formed of an insert matrix with a high viscosity molten resin, and a heat-resistant resin member manufactured using this method. <P>SOLUTION: This insert molding method has a process to inject a molten heat-resistant resin into an injection molding die in which the insert matrix is inserted. In addition, the insert matrix forms the narrow gap part with the surface covered with an amorphous material. The heat-resistant resin member manufactured using this method is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an insert molding method suitable for manufacturing a heat resistant resin member, and a heat resistant resin member manufactured by the insert molding method.

  Insert molding is used for manufacturing a composite member made of a resin and another member. For example, Japanese Patent Application Laid-Open No. 2004-32911 (Patent Document 1) describes a method of manufacturing a bus bar circuit body, which is an automotive part, by insert molding (Claim 1). Here, a bus bar (metal member) is installed in an injection mold, and a molten resin is further injected to manufacture a bus bar circuit body that is a composite member composed of a bus bar and a resin member.

  In insert molding, an insert base material such as the bus bar is inserted into a mold, and this base material becomes a physical obstacle to resin flow when molten resin is injected. In addition, when a narrow gap portion (hereinafter referred to as “narrow gap portion”) is formed between the insert base materials, etc., and the viscosity of the injected molten resin is high, it is difficult to fill the narrow gap portion with resin. . For example, a portion that is not filled with resin tends to occur on the opposite side of a gate (injection gate) into which resin is injected (easy to short-circuit).

  In particular, when the insert base material is a metal, the resin fluidity is deteriorated. In the case of metal, it is considered that the slip condition between the metal surface and the resin is lowered due to the surface state. Therefore, in this case, it becomes more difficult to fill the narrow gap with resin.

  As a method for reliably filling a molten resin having a high viscosity to the narrow gap portion and preventing the short circuit, a method of providing an injection gate on the opposite side of the injection gate and injecting the resin from both sides of the narrow gap portion can be considered. However, this method has a problem that the injection facility is complicated and bubbles are likely to be generated at the junction of the resins.

  In order to facilitate filling of the resin into the narrow gap portion, a method of increasing the molding temperature and pressure is also effective. However, if the molding temperature and pressure are increased too much, problems such as deterioration of the resin, deformation of the base material, and occurrence of flash will occur.

By reducing the viscosity of the molten resin to be filled, it is possible to easily fill the narrow gap with the resin. Japanese Patent Laid-Open No. 2001-162643 (Patent Document 2) discloses a method of adding a fluidizing agent to a resin as a method for facilitating filling of the resin into the narrow gap portion (claims). 1).
JP 2004-32911 A JP 2001-162643 A

  However, when the viscosity of the molten resin is lowered, the heat resistance of the resin is lowered. Also, as described in Patent Document 2, when a free-flowing agent is added to the resin, the heat resistance of the resin is lowered. Therefore, these methods cannot be used for manufacturing a heat-resistant resin member.

  The present invention is an insert molding method used for manufacturing a heat resistant resin member, and can insert a molten resin having a high viscosity into a narrow gap formed by an insert base material easily and reliably. It is another object of the present invention to provide a heat resistant resin member manufactured by using this method.

  The subject is an insert molding method including a step of injecting a molten heat-resistant resin into an injection mold in which an insert base material is inserted, wherein the insert base material forms a narrow gap portion, and the insert This is achieved by an insert molding method (claim 1) characterized in that the surface of the base material in the narrow gap is covered with an amorphous material.

  As a result of the study, the present inventor coated the surface of the insert base material with an amorphous material to improve the resin fluidity (slidability between the surface of the base material and the resin) and is formed of the insert base material. As a result, it was found that the resin could be easily filled into the narrow gap portion, and problems such as short circuit did not occur, and the present invention was completed.

The amorphous material is preferably a material having a thermal expansion coefficient of 6 × 10 ⁻⁶ / ° C. or more from room temperature to 300 ° C. Claim 2 corresponds to this preferable mode. More preferably, the material is 8 to 23 × 10 ⁻⁶ / ° C. If cracks occur due to temperature changes, it is difficult to hold the amorphous material on the surface of the insert base material. By setting the thermal expansion coefficient within this range, the difference in thermal expansion from the insert base material is reduced. In addition, cracks due to temperature changes can be prevented. Here, the thermal expansion coefficient from room temperature to 300 ° C. refers to the slope of the TMA curve from room temperature to 300 ° C.

Here, the amorphous material refers to a material having a small proportion of crystallized components, and includes SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , P ₂ O ₅ , Li ₂ O, Na ₂ O, and K. Preferred examples include glass obtained by mixing and melting an inorganic oxide selected from ₂ O, MgO, CaO, TiO ₂ , ZnO, PbO, and the like. If the proportion of the crystallized component is large, the surface shape of the layer made of an amorphous material covering the surface of the insert base material (hereinafter referred to as “amorphous layer”) becomes rough, and the fluidity of the resin decreases. It becomes difficult to fill the narrow gap with resin.

  When the amorphous material is the glass, the thermal expansion coefficient varies depending on the ratio of P oxide and B oxide and the content of alkali metal oxide. Therefore, by adjusting these, the thermal expansion coefficient in the above range can be obtained.

That is, the thermal expansion coefficient in the more preferable range, 8 to 23 × 10 ⁻⁶ / ° C., is obtained by using P oxide, B oxide and alkali metal oxide as the inorganic oxide constituting the glass. Can do. Glass composed of P oxide, B oxide and alkali metal oxide has excellent characteristics such as being more difficult to crystallize and obtaining a stable glass state, and does not contain lead-based substances harmful to the human body. Therefore, it is preferable.

Examples of the P oxide and B oxide include P ₂ O ₅ and B ₂ O ₃ , respectively. The molar ratio of P ₂ O ₅ : B ₂ O ₃ is preferably in the range of 1: 0.9 to 1: 3.5. By setting it as this range, the glass which has a thermal expansion coefficient of 8-23 * 10 < ^-6 > / degreeC is easily obtained. As the alkali metal oxide, Li ₂ O, Na ₂ O, or K ₂ O is preferable because of its availability. The glass may further contain an oxide having a melting point higher than that of P oxide and B oxide, such as Al ₂ O ₃ and SiO ₂ .

  The thickness of the amorphous layer may be 1 μm. Many amorphous materials have low thermal conductivity, and if the amorphous layer is thick, problems such as heat generation due to a decrease in thermal conductivity and cracks may occur.

  The amorphous layer is preferably formed on the entire surface of the insert base material at the narrow gap portion, that is, the surface of the portion forming the narrow gap portion. The effect of the present invention can be obtained even if a portion of the surface of the portion forming the narrow gap portion is not covered with the amorphous layer. However, the larger the portion covered with the amorphous layer, the larger the portion covered with the amorphous layer. This is preferable because a greater effect can be obtained. Therefore, it is more preferable that the entire surface of the portion forming the narrow gap portion is covered with an amorphous layer because the maximum effect can be obtained.

  A method for forming the amorphous layer on the surface of the insert base material is not particularly limited, and examples thereof include a coating method using a coater, a dipping method, and a vapor phase synthesis method. Specifically, as the application method and the dipping method, the dispersion is applied to the base material by a method such as immersing the insert base material in the dispersion of the amorphous material powder, and then heated to heat the powder. A method of melting, cooling and solidifying, a method of making an amorphous material into a sol-gel solution and applying, heating and melting, cooling and solidifying in the same manner as the above dispersion, an amorphous material (glass) Examples include a method in which an insert base material is dipped in a melt of an inorganic oxide to be formed, pulled up, cooled, and solidified.

  The material of the insert base material used in the present invention is not particularly limited. However, when the insert base material is a metal, the fluidity of the resin is particularly low, and the problem in filling the narrow gap portion is large. However, since this problem is solved by the present invention, the insert base material is made of metal. In particular, the effects of the present invention are exhibited.

  As the metal used for the insert base material, copper, iron, aluminum, or an alloy containing at least one of them as a main component is often used from the viewpoint of price, strength, and the like. Claim 3 corresponds to this aspect, and is the above-described insert molding method, wherein the insert base material is made of copper, iron, aluminum, or an alloy mainly composed of at least one selected from these. An insert molding method is provided.

The coefficients of thermal expansion of copper, iron, and aluminum from room temperature to 300 ° C. are 17 × 10 ⁻⁶ / ° C., 12 × 10 ⁻⁶ / ° C., and 23 × 10 ⁻⁶ / ° C., respectively. The difference in thermal expansion between the amorphous material having a coefficient of thermal expansion of 6 × 10 ⁻⁶ / ° C. or higher is small, and the problem of crack generation due to temperature change is less likely to occur. In addition, conductors such as silver (thermal expansion coefficient: 19 × 10 ⁻⁶ / ° C.), gold (thermal expansion coefficient: 14 × 10 ⁻⁶ / ° C.), and nickel (thermal expansion coefficient: 13 × 10 ⁻⁶ / ° C.) Even in the case of using, the difference in thermal expansion from the amorphous material is small, and the problem of crack generation due to temperature change is less likely to occur.

  As the heat-resistant resin used in the insert molding method of the present invention, a thermoplastic resin having a high thermal deformation temperature, in particular, a thermoplastic resin having a thermal deformation temperature of 200 ° C. or higher, or an inorganic additive is added to the thermal deformation temperature. Resins having a temperature of 200 ° C. or higher are preferably used, and the effects of the present invention are particularly exhibited when these resins are used. Here, the thermal deformation temperature refers to the inflection point of the TMA curve.

  Claim 4 corresponds to this preferred embodiment, and is the insert molding method described above, wherein the heat-resistant resin has a heat-deformation temperature obtained by adding a thermoplastic resin having a heat-deformation temperature of 200 ° C. or higher, or an inorganic additive. The present invention provides an insert molding method characterized by being a resin having a temperature of 200 ° C. or higher.

  A resin member having excellent heat resistance can be obtained by carrying out the insert molding method of the present invention using such a heat resistant resin. This heat-resistant resin has a high melt viscosity and is difficult to fill into the narrow gap portion in insert molding, but is easily filled into the narrow gap portion by the insert molding method of the present invention.

  Examples of the thermoplastic resin having a heat distortion temperature of 200 ° C. or higher include thermoplastic resins such as polyimide, polyamideimide, polyethersulfone, and polyetherimide. Examples of the resin having a heat distortion temperature of 200 ° C. or more by adding an inorganic additive include polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, 6 nylon, polybutylene terephthalate, and polyethylene terephthalate.

Examples of inorganic additives include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titanium oxide, zirconia, magnesium hydroxide, aluminum hydroxide, carbon, etc., or a combination or combination of these particles and short fibers. Or a plate-like additive made of talc, mica, montmorillonite or the like.

  In the insert molding method of the present invention, an insert base material as described above is first inserted into an injection mold. As the injection mold, the same mold as that used in conventional normal injection molding or insert molding can be used. There is no need to increase the number of injection gates, and according to the present invention, it is not difficult to fill the narrow gap with the resin even with a normal number of injection gates.

  Resin is injected and injected into the cavity of the mold in which the insert base material is inserted. There is no particular limitation on the size and shape of the narrow gap formed by the insert base material. The range of the thickness (gap) of the narrow gap portion where the effect of the present invention is greatly exerted varies depending on the type of resin, the width and length of the narrow gap portion, etc. The filling of the resin into the narrow gap is very difficult. On the other hand, according to the present invention, the resin can be filled easily, so that the effect of the present invention is particularly exhibited.

  As for the molding temperature and pressure, the same conditions as in conventional normal injection molding and insert molding can be adopted. According to the present invention, the resin can be easily filled into the narrow gap portion even at the same molding temperature and pressure as in the prior art.

  The present invention further provides a heat-resistant resin member (Claim 5) manufactured by the insert molding method. Since this heat-resistant resin member is formed by filling a narrow gap formed by an insert base material with resin, it has a thin layer portion (a portion where the resin is thin) of the heat-resistant resin. In the insert molding method, the insert base material and the heat-resistant resin are integrally molded, but the heat-resistant resin member of the present invention is a molded product in which the insert base material and the heat-resistant resin are integrated (bonded). It is suitably used for automobile members and the like.

  In addition, after molding, the insert base material may be removed and used as a molded product made of only resin. Further, when the insert base material is fixed to the mold wall surface, or when the insert base material and the mold are integrated (in these cases, the insert base material can be considered as a part of the mold). Even if the portion forming the narrow gap portion of the insert base material is covered with an amorphous material, the effect of the present invention that the filling of the resin into the narrow gap portion is facilitated. can get. In this case, when the molded product is taken out from the mold, the insert base material is removed, and a molded product made of only the resin having the thin layer portion is obtained.

  In the insert molding method of the present invention, a melted heat resistant resin, that is, a molten resin having a high viscosity can be easily and surely filled into a narrow gap formed by the insert base material. Therefore, it is made of a heat-resistant resin without employing means such as increasing the number of injection gates, increasing the molding temperature or pressure, that is, means for complicating the molding apparatus, or means for easily causing deterioration of the resin. A resin member having a thin resin molded portion can be easily produced.

  Since the heat-resistant resin member of the present invention is produced by the insert molding method having the excellent characteristics as described above, it is a molded resin member having excellent heat resistance. And it is used suitably for the member for motor vehicles etc. as a molding resin member which has the thin layer part of resin which removed the insert base material after shaping | molding as a composite member integrated (bonded) with the insert base material.

  Next, the best mode for carrying out the invention will be described with reference to the drawings. This form does not limit the scope of the present invention and can be changed without departing from the spirit of the present invention.

  FIG. 1 is a cross-sectional view showing a state in a mold after resin filling in the insert molding method of the present invention.

  First, an insert base material 2 is inserted into an injection mold 1 having a cross-sectional shape shown in FIG. As the insert base material 2, for example, a material made of copper is used. As is apparent from FIG. 1, in this example, two insert base materials 2 are inserted in close contact with the wall of the injection mold 1 and a narrow gap 3 is formed between the base materials.

The surface of the insert base material 2 on the narrow gap portion 3 side is covered with glass (33B ₂ O ₃ -33P ₂ O ₅ -33 (Li ₂ O + K ₂ O) -5Al ₂ O ₃ ), and the amorphous layer 4 is covered. Forming. The thickness of the amorphous layer 4 is often about 20 to 50 μm. Further, in many cases, an amorphous thermal expansion coefficient is particularly preferably about 14 × 10 ⁻⁶ / ° C.

The amorphous layer 4 is, for example, a liquid in which the material constituting the glass is pulverized to a particle size of 50 μm or less and dispersed in a solvent (α-terpineol and N-methyl-2-pyrrolidone) to a concentration of 40% by weight. Can be formed by a method of baking at 570 ° C. for 10 minutes in an O ₂ 1000 ppm atmosphere after coating the surface of the insert base material 2 on the narrow gap portion 3 side. In addition, when the dipping method is adopted for forming the amorphous layer, the amorphous layer is also formed on the side in close contact with the wall of the mold. As described above, for the purpose of facilitating the formation of the amorphous layer, an amorphous layer may be formed on the side in close contact with the mold wall. The layer portion does not contribute to the effect of the present invention.

  After the insert base material 2 is inserted, the molten heat resistant resin 6 is injected and injected from the injection gate 5. When the heat resistant resin 6 is LCP (manufactured by Sumitomo Chemical Co., Ltd., trade name: E5008), it is injected and injected under the conditions of a nozzle temperature of 400 ° C., a substrate temperature of 160 ° C., and a pressure of 120 MPa. Note that the thermal deformation temperature of E5008 is 335 ° C. Even if the gap of the narrow gap portion 3 is about 0.3 mm, the flow of the heat-resistant resin 6 is good because the surface of the insert base material 2 is covered with the amorphous layer 4, and the opposite side of the injection gate. There is no short circuit.

  After the heat resistant resin 6 is injected and the injection mold 1 including the narrow gap portion 3 is sufficiently filled with the heat resistant resin 6, it is cooled and the heat resistant resin 6 is solidified. After solidification, it is taken out from the injection mold 1 to obtain a heat resistant resin molded body in which the insert base material 2 and the heat resistant resin 6 are integrated.

  The heat-resistant resin molded body in which the insert base material and the heat-resistant resin thus obtained are integrated is used as an automobile member or the like. In some cases, the insert base material is removed from the heat-resistant resin molded body to be used as a molded body made of only the heat-resistant resin 6. A molded body made of only the heat-resistant resin 6 has a thin layer portion of the resin. In some cases, only one of the two insert base materials is removed, and a molded body in which the resin and one insert base material are integrated is used.

It is sectional drawing which shows the state of the injection mold after heat resistant resin filling.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection mold 2 Insert base material 3 Narrow gap part 4 Amorphous layer 5 Injection gate 6 Heat resistant resin

Claims (5)

  An insert molding method including a step of injecting a molten heat-resistant resin into an injection mold in which an insert base material is inserted, wherein the insert base material forms a narrow gap portion, An insert molding method, wherein a surface of the narrow gap portion is covered with an amorphous material. 2. The insert molding method according to claim 1, wherein the amorphous material is a material having a thermal expansion coefficient of 6 × 10 ⁻⁶ / ° C. or more from room temperature to 300 ° C. 3.   The insert molding method according to claim 1 or 2, wherein the insert base material is made of copper, iron, aluminum, or an alloy containing at least one selected from them as a main component.   The heat-resistant resin is a thermoplastic resin having a heat distortion temperature of 200 ° C or higher, or a resin having a heat distortion temperature of 200 ° C or higher by adding an inorganic additive. 4. The insert molding method according to any one of 3. A heat-resistant resin member produced by the insert molding method according to any one of claims 1 to 4.

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