JP5388658B2 - Composite molded article and manufacturing method thereof - Google Patents

Description

  The present invention relates to a composite molded article suitable for an electromagnetic wave shielding material and a magnetic shielding material, and a method for producing the same.

  For example, parts and members mounted on or incorporated in automobiles are, for example, about −40 ° C. before starting the engine in a cold region, but rapidly warm after starting the engine. It is done. Therefore, such parts and members are subjected to severe thermal shock and are exposed to large thermal expansion. On the other hand, in an extremely hot region, contrary to a cold region, parts and members that are at a high temperature are rapidly cooled by an air conditioner after the engine is started. That is, such components and members are also subjected to severe thermal shock and are exposed to large thermal expansion.

  By the way, when such parts and members are composed of a metal base material and a resin layer formed on the base material and are manufactured based on an insert molding method or an outsert molding method, the base material and the resin Due to the difference in the linear expansion coefficient of the layers, the resin layer is subjected to significant stress concentration. As a result, immediately after molding, in the worst case, the resin layer is cracked due to a temperature change during use, or the resin layer is peeled off from the substrate. Recently, the structure of such parts is complicated, there are many parts where the thickness of the resin changes, the temperature used in the vicinity of the engine is large, and the thinness of the resin part due to downsizing and weight reduction of parts. For this reason, cracking of the resin is likely to occur. Accordingly, a component that can withstand such a long-term temperature change, that is, a component excellent in heat shock resistance has been strongly demanded.

  For example, Japanese Patent Application Laid-Open No. 2001-007574 discloses an electronic device that hardly undergoes deformation such as warping. This electronic device is an electronic device provided with an assembly part to which one or more molded parts are attached. At least one through hole is formed in the assembly part, and at least one molded part is integrally formed with a main body of the molded part and a plurality of engaging portions slidably fitted in the through holes of the assembly part. A part mounting hole is formed in at least one head of the plurality of engaging portions.

JP 2001-007574 A

  However, when manufacturing an electronic device having such a structure, since the projections that become the engaging portions are formed in a state where a gap is formed in the through hole of the base material, the shape of the mold is complicated, Under normal molding conditions, a desired molded product may not be obtained, and it is difficult to say that it is efficient. In addition, the molded product obtained has a problem that the resin layer is cracked or peeled off from the base material due to temperature change during use because the molded component is only caught on the assembly part at the engaging part. There is a case.

  Accordingly, an object of the present invention is to provide a metal and a thermoplastic resin that are less likely to crack in the resin layer by injection molding using a mold having a simple structure without using a mold having a complicated structure. Another object of the present invention is to provide a method for producing a composite molded article.

The manufacturing method of the composite molded article of the present invention for achieving the above object is as follows.
(First feature)
(A) Injecting a substantially box-shaped metal base material comprising a plate-like portion having a plurality of through-holes, at least a part of which has a long hole shape, and a side wall provided at an edge of the plate-like portion. After mounting in the mold cavity,
(B) By injecting a crystalline thermoplastic resin into the cavity, and forming a crystalline thermoplastic resin layer straddling a plurality of through-holes and continuing on both sides of the plate-like portion via the through-holes , Producing a composite molded product of the base material and the crystalline thermoplastic resin layer,
(C) After taking out the composite molded product from the mold, the crystalline thermoplastic resin is crystallized so that the crystallinity of the crystalline thermoplastic resin is 1% or more higher than the crystallinity after taking out the mold. Thus, the production of a composite molded product characterized in that the crystalline thermoplastic resin in the through-hole having a long hole shape is contracted in the long axis direction of the long hole to form a void at the end of the long axis Method.
(Second feature)
The through hole having a long hole shape is provided so that a major axis thereof is substantially aligned with a line connecting the molten resin injection portion trace and the through hole in the case of a composite molded product. Manufacturing method of composite molded article.
(Third feature)
Through holes having a long hole shape, characterized in that the ratio of the length of the major axis (L _L) and the length of the minor axis _{(L S) (L L /} L S) is 2 or more The manufacturing method of the composite molded product as described above.
(Fourth feature)
The method for producing a composite molded article as described above, wherein the crystallization treatment is performed in an air atmosphere at a temperature of 60 ° C. to 120 ° C. for a time of 0.5 hours to 2 hours.
(Fifth feature)
When the linear expansion coefficient of the material constituting the substrate is α _M and the linear expansion coefficient of the crystalline thermoplastic resin is α _R ,
1 × 10 ⁻⁵ / ° C ≦ α _R −α _M ≦ 15 × 10 ⁻⁵ / ° C
The method for producing a composite molded article as described above, wherein:
(Sixth feature)
The method for producing a composite molded article as described above, wherein the crystalline thermoplastic resin is a polyacetal resin.

The characteristic points of the composite molded article of the present invention are shown below.
(Seventh feature)
(A) a substantially box-shaped metal substrate comprising a plate-like portion having a plurality of through-holes, at least a part of which is in the shape of a long hole, and a side wall provided at an edge of the plate-like portion;
(B) a composite molded article composed of a crystalline thermoplastic resin layer straddling a plurality of through-holes of the base material and continuous on both sides of the plate-like portion via the through-holes,
A composite molded article characterized in that a void is formed at the end of the long axis of a through hole having a long hole shape by crystallizing a crystalline thermoplastic resin.
(Eighth feature)
The composite molded article as described above, wherein the composite molded article is an electromagnetic shielding material or a magnetic shielding material.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1A is a perspective view of the metal substrate 1. FIG. 1B is a view of the metal substrate 1 as viewed from above. FIG. 1C is a schematic plan view of a through hole provided in the metal base material of Example 1. FIG. FIG. 2A is a perspective view of the composite molded product 6. FIG. 2B is an AA end view of FIG. (C) of FIG. 2 is a BB end view in FIG. 1 (B).

  In the present invention, a substantially box-shaped metal base material comprising a plate-like portion having a plurality of through-holes, at least a part of which is in the shape of a long hole, and a side wall provided at an edge of the plate-like portion, For example, not only metals such as aluminum, magnesium, steel, iron, lead, tin, zinc, copper, nickel, cobalt, chromium, titanium, zirconium, gold, silver, but also alloys thereof (for example, stainless steel and brass) It consists of a plate-like part 2 and a side wall 3 provided at the edge of the plate-like part 2 as shown in FIG. It is a substantially box-shaped one that can be used.

  Here, the box shape means that the shape is not composed of a single plate-like portion 2, and has a side wall 3 at a part of the edge of the plate-like portion 2, and the substrate 1 itself has a certain degree of rigidity. It means that it is a shape shown in the figure, and it is not intended to form a composite with a resin and easily deform as the resin shrinks. Therefore, the shape of the plate-like portion 2 is arbitrary such as a rectangle, a circle, a shape connecting a circle and a rectangle, a hemisphere, and the like. The plate-like portion 2 is preferably flat, but may be curved as long as the substrate 1 itself can exhibit some rigidity. The side wall 3 should just be provided in a part of edge part of the plate-shaped part 2. FIG. That is, the side wall 3 may not be provided on all the edges of the plate-like portion 2.

  When the composite molded article of the present invention is used as an electromagnetic wave shielding material, the metal constituting the substrate 1 is not only a metal such as zinc, lead, silver, copper, gold, aluminum, nickel, iron, magnesium, titanium, but also It is preferable to use an alloy (for example, stainless steel). On the other hand, when the composite molded product of the present invention is used as a magnetic shielding material, not only metals such as iron, nickel, cobalt, and zinc but also alloys thereof (for example, stainless steel) are used as the metal constituting the substrate 1. It is preferable. Such a substrate 1 is generally manufactured by die-casting a metal (alloy-containing) or press-molding a metal plate.

Further, as the metal constituting the substrate 1, when the linear expansion coefficient of the metal is α _M and the linear expansion coefficient of the crystalline thermoplastic resin is α _R ,
1 × 10 ⁻⁵ / ° C ≦ α _R −α _M ≦ 15 × 10 ⁻⁵ / ° C,
Preferably
3 × 10 ⁻⁵ / ° C ≦ α _R −α _M ≦ 12 × 10 ⁻⁵ / ° C
Those satisfying the above are preferable. In the present invention, the linear expansion coefficient α _M of the material constituting the substrate 1 conforms to JIS Z2285, the linear expansion coefficient α _R of the crystalline thermoplastic resin conforms to ISO 11359-2, and the temperature ranges from 23 ° C. to 80 ° C. It is a value measured in the range of ° C. Here, the linear expansion coefficient α _R of the crystalline thermoplastic resin is a linear expansion coefficient in the resin flow direction (MD).

  A plurality of through holes 4, 4 ′, 4 ″, 5, 5 ′ formed in the plate-like portion 2 of the base material 1 are generally formed when the base material 1 is molded, but post-processing In the present invention, some of the through holes formed in the base material 1 need to have a long hole shape, and the through holes are usually formed in the plate-like portion 2. A plurality are formed, but may be further provided on the side wall 3.

  The metal substrate 1 thus obtained is mounted in the cavity of the injection mold. Next, the crystalline thermoplastic resin is injected into the cavity, straddles the plurality of through holes 4, 4 ', 4 ", 5, 5' and continues to both sides of the plate-like portion 2 through the through holes. By forming the crystalline thermoplastic resin layers (the first resin layer 7 and the second resin layer 8) to be produced, the composite molded product 6 of the substrate 1 and the crystalline thermoplastic resin is produced. In the composite molded product 6, the first resin layer 7 is formed on almost the entire surface of the plate-like portion 2 (usually the outer surface), and the first resin layer 7 is formed through the through holes 4, 4 ′, 4 ″, 5, 5 ′. It is assumed that the second resin layer 8 is formed on the opposite side. That is, the first resin layer 7 is connected across a plurality of through holes 4, 4 ″, 4 ″ and through holes 5, 5 ′ formed at positions away from the through holes 4, 4 ″, 4 ″. The second resin layer 8 is present protruding from the through holes 4, 4 ′, 4 ″, 5, 5 ′ to the inside of the base material 1. The resin connecting portion 9 that connects the second resin layer 8 refers to a resin portion located in the through holes 4, 4 ', 4 ", 5, 5'. That is, the crystalline thermoplastic resin layer is formed across a plurality of through holes, but the portion of the crystalline thermoplastic resin layer across the plurality of through holes is formed only on one surface of the substrate. It may be formed on both sides of the substrate.

  When such a composite molded product 6 is simply formed (when the shape of the through hole is not the long hole shape of the present invention), the linear expansion coefficient of the metal of the base material 1 and the crystalline thermoplastic resin are greatly different. A difference in molding shrinkage between the base material 1 and the crystalline thermoplastic resin occurs, and there is a shrinkage stress in the vicinity of the through hole or between the through hole and the through hole (for example, between the through hole 4 and the through hole 5). There is a problem that the first resin layer 7 is cracked in the vicinity of the through holes or between the through holes, or the base material 1 is deformed in some cases.

  In order to solve such a problem, the present invention makes a part of the through hole (a through hole located near the end of the composite molded product 6) a long hole shape, and composite molding taken out from the mold after molding Due to the special treatment of the product 6, it occurs due to the deformation that occurs when the metal base 1 and the crystalline thermoplastic resin are integrally molded, and the difference in the linear expansion coefficient between the metal and the crystalline thermoplastic resin. This prevents cracking of the resin.

In the present invention, the long hole shape, when the length of the major axis L _L, and the length L _S of the short axis, is intended to mean an elongated shape which satisfies the relationship _L L> L _S. As shown in the schematic plan view of the through hole in FIG. 1C, the long axis in the long hole shape is the longest line among the line segments connecting any two points of the edge of the through hole. A straight line connecting the two points P ₁₁ and P ₁₂ where the minute is obtained is indicated. On the other hand, the short axis in the long hole shape connects the two points P ₂₁ and P _{22 at} which the longest line segment is obtained among the line segments connecting the two points where the straight line perpendicular to the long axis intersects the edge of the through hole. Point to a straight line. In the through hole having a long hole shape, the ratio of the length of the long axis to the length of the short axis (L _L / L _S ) is 2 or more, preferably 3.5 or more. In addition, although it does not limit as an upper limit of the value of L _L / L _S , 10 can be mentioned, for example.

  The shape of the long hole includes a combination of two line segments and two semicircles, a combination of two line segments and two arbitrary curves, a portion that is substantially parallel to a symmetric position with respect to the center of gravity, and two half halves. Combinations of circles (oval), triangles, rounded triangles, quadrangles, rounded quadrangles, polygons with pentagons or more, polygons with rounded pentagons or more, ellipses, hyperbola and parabola combinations, any A curve can be mentioned. Among these, a combination of two line segments and two semicircles, an oval, an ellipse, and a rounded quadrangle are preferable. When there is a through hole that is not a long hole shape, the shape of the through hole is arbitrary.

Hereinafter, of the through holes 4, 4 ′, 4 ″, 5, 5 ′ having the long hole shape, the through hole 4 will be described as an example. The through hole 4 having the long hole shape is formed with the composite molded product 6. In this case, the major axis of the molten resin injection portion trace 10 and the through hole 4 is provided so that the major axis is substantially aligned with the molten resin remaining in the crystalline thermoplastic resin layer. A straight line connecting the center of the resin injection part mark 10 and the center of the through hole 4 having a long hole shape (see the dashed line in FIG. 1B or FIG. 3A) and the through hole having a long hole shape When the angle formed by the major axis of 4 is θ ₁ ,
| Θ ₁ | ≦ 30 degrees Preferably,
It can be defined that | θ ₁ | ≦ 25 degrees is satisfied. In addition, when the molten resin injection part is composed of a multi-point gate structure having a plurality of resin injection ports, the trace of the resin injection port closest to each through hole having a long hole shape is marked with respect to each through hole. What is necessary is just to set it as the molten resin injection part trace 10. FIG.

On the other hand, although this is not strict, the resin layer having the larger area out of the first resin layer 7 and the second resin layer 8 (the first layer in FIGS. 2B and 2C). When the angle formed between the main heat shrink direction of the resin layer 7) and the long axis of the through hole having a long hole shape is θ ₂ ,
| Θ ₂ | ≦ 30 degrees Preferably,
It can also be defined that | θ ₂ | ≦ 25 degrees.

  The first resin layer 7 and the second resin layer 8 cover the through hole 4 having a long hole shape and other through holes so as to be sandwiched from above and below, and in the state after molding, the first resin layer 7 And the 2nd resin layer 8 has covered the through-hole in the state completely sealed without gap. In the present invention, after obtaining such a composite molded product, the composite molded product 6 is taken out from the mold, and the crystalline thermoplastic resin is crystallized to thereby increase the crystallinity of the crystalline thermoplastic resin. A crystallization treatment is performed to increase the crystallinity after removal of the mold by 1% or more, preferably 3% or more, so that the crystalline thermoplastic resin in the through hole having a long hole shape contracts in the long axis direction of the long hole. The void 12 is formed at the end of the long axis. Note that voids can also be formed in the minor axis direction. After the injection of the crystalline thermoplastic resin into the cavity is completed and the mold is opened, and before the above crystallization process is performed, the through hole 4 having the long hole shape and the resin connecting portion 9 are There are virtually no voids in between.

  The crystallization treatment method is not particularly limited as long as the crystallization degree of the crystalline thermoplastic resin can be made 1% or more higher than the crystallization degree after being taken out from the mold, but preferably air It is desirable to carry out in an atmosphere at a temperature not higher than the melting point of the crystalline thermoplastic resin for a period of 0.5 to 2 hours. A more preferable temperature range is a temperature of 60 ° C to 120 ° C. The crystallinity after the crystallization treatment is preferably 2% or more higher than the crystallinity after removal from the mold.

In the composite molded product 6 subjected to the crystallization treatment, a void 12 is formed at the end of the long axis in the through hole 4 having a long hole shape. The length of the gap 12 along the long axis formed at the end of the long axis of the through hole 4 having the long hole shape depends on the size / shape of the composite molded product, the size / shape of the through hole, and the crystalline heat used. depending on the shrinkage or the like of the thermoplastic resin, for example, 0.01% of the length L _L of the major axis of the through hole is preferably 0.05% or more, more preferably 0.1% or more. Note that the upper limit value of the length of the gap 12 is not limited, but may be, for example, 3% of the length L _L of the long axis of the through hole.

  Furthermore, the composite molded article of the present invention including the preferred embodiment and configuration described above is held at a temperature of 130 ° C. for 1 hour, then at a temperature of −40 ° C. for 5 seconds, and at −40 ° C. for 1 hour. After the holding, when the thermal cycle test at a temperature of 130 ° C. for 5 seconds is executed 100 times, it is desirable that the crystalline thermoplastic resin layer is not damaged.

  Furthermore, in the present invention including the preferred modes and configurations described above, the second resin layer 8 has a configuration in which a mounting portion 11 for mounting an article to be stored in the composite molded product is provided. It is desirable to do. Here, examples of the attachment portion include bosses and ribs. Examples of the article include various printed wiring boards, connectors, wiring, various windings, and magnetic coils.

  Furthermore, in the present invention including the preferred embodiments and configurations described above, as the crystalline thermoplastic resin, specifically, polyacetal (polyoxymethylene) resin; polyolefin resin such as polyethylene resin and polypropylene resin; polyamide 6 Polyamide resins such as polyamide 66 and polyamide MXD6; polyester resins such as polyethylene terephthalate (PET) resin and polybutylene ethylene terephthalate (PBT) resin; and polyphenylene sulfide resins, among which polyacetal resin is used. Is preferred. Here, whether or not the thermoplastic resin is a crystalline thermoplastic resin is generally determined by a differential scanning calorimetry (DSC) method. Crystallinity means a case where it has a clear melting point (a temperature showing a rapid endotherm) or a measurable heat of fusion. In the present invention, the heat of fusion measured using a commonly used differential scanning calorimeter is used. 1 cal / g or more. Specifically, for example, using a DSK-II manufactured by PERKIN-ELMER, the heat of fusion is raised to a temperature higher than the expected melting point at a rate of 10 ° C./min. The temperature can be measured by lowering the temperature to 30 ° C. at a rate of 10 ° C./minute, holding it for 2 minutes, and then increasing the temperature again at a rate of 10 ° C./minute. When measured in this way, the resin whose melting peak with a heat of fusion of 1 cal / g or more is confirmed at the second temperature rise is a crystalline thermoplastic resin, while the clear melting point of 1 cal / g or more is 2 A resin that is not confirmed at the time of the second temperature increase is an amorphous thermoplastic resin.

  As a molten resin injection part, a one-point side gate structure with one resin injection port, a multi-point side gate structure with a plurality of resin injection ports, and a film gate structure (sometimes called a flash gate structure) Examples include a direct gate structure, a pin gate structure, a submarine gate structure, a diaphragm gate structure, and a tunnel gate structure.

In the method for producing a composite molded article of the present invention, after the injection of the crystalline thermoplastic resin into the cavity is completed and the mold is opened, the crystalline thermoplastic resin is crystallized after the composite molded article is taken out from the mold. The degree DOC ₁ can be measured based on the following method.

  The composite molded product 6 is taken out from the mold and left at room temperature for 12 hours, and then a sample of about 10 mg is obtained from the first resin layer 7 formed on the outer surface of the plate-like portion 2 or the side wall 3 of the base material 1. The sample was heated by DSC from 30 ° C to the melting point of the resin (usually the expected melting point of the resin + 40 ° C) at a rate of 10 ° C / min. And the degree of crystallinity is calculated by the following equation.

Crystallinity DOC ₁ (%) = [heat amount of endothermic peak (J / g) −heat amount of exothermic peak (J / g)] / [theoretical heat of fusion of crystalline thermoplastic resin (J / g)] × 100

In addition, the measuring method of the theoretical heat of fusion of each resin in the present invention is as follows.
For example, when the crystalline thermoplastic resin is a polyacetal resin, the endothermic peak heat at the melting point of the polyacetal resin having various crystallinities is measured by DSC, and the obtained endothermic peak heat and crystallinity are biaxial. A calibration curve was created by plotting, and the calorific value at the extrapolation point of 100% crystallinity of the calibration curve was defined as the theoretical heat of fusion. For measuring the crystallinity of the polyacetal resin used for DSC measurement, for example, a density gradient tube method (JIS K7112) prepared with a carbon tetrachloride / toluene mixed solvent at 25 ° C. can be used. The above is an example in which the crystalline thermoplastic resin is a polyacetal resin. However, in the case of other crystalline thermoplastic resins, the theoretical heat of fusion can be determined by the same method.

The crystallinity DOC ₂ of the crystalline thermoplastic resin after completion of the crystallization treatment is also about 10 mg from the first resin layer 7 after leaving the composite molded product after completion of the crystallization treatment at room temperature for 12 hours. samples were cut out, it can be obtained in the same manner as the measurement of the crystallinity of DOC _1.

The composite molded article, electromagnetic wave shielding material or magnetic shielding material of the present invention is
(A) a substantially box-shaped metal substrate comprising a plate-like portion having a plurality of through-holes, at least a part of which is in the shape of a long hole, and a side wall provided at an edge of the plate-like portion;
(B) a composite molded article composed of a crystalline thermoplastic resin layer straddling a plurality of through-holes of the base material and continuous on both sides of the plate-like portion via the through-holes,
It is a composite molded product characterized in that a void is formed at the end of the long axis of a through-hole formed into a long hole by crystallizing a crystalline thermoplastic resin, or such a composite molded product An electromagnetic shielding material or a magnetic shielding material comprising

  Moreover, as a specific shape of the composite molded article of the present invention, an arbitrary box shape including a cube and a rectangular parallelepiped can be exemplified. Moreover, the thickness of the 1st resin layer 7 and the 2nd resin layer 8 is 0.5-4 mm normally, Preferably it is 0.8-3 mm.

  Specific examples of the composite molded article, electromagnetic wave shielding material or magnetic shielding material of the present invention include engine parts, automobile parts such as control control units, electric / electronic parts, home appliances, and building materials.

  In the present invention, the first resin layer 7 and the second resin layer 8 are connected by a resin connecting portion 9 having at least two long hole shapes. Therefore, there is an excellent effect that the problem that the base material 1 and the crystalline thermoplastic resin layer are separated does not occur. In addition, a gap 12 is formed between the long-axis end portion of the through-hole (4, 4 ′, 4 ″, 5, 5 ′) having a long hole shape and the resin connecting portion 9, and the first resin The layer 7 and the second resin layer 8 cover the through-hole having a long hole shape, and therefore, there is little occurrence of resin cracking or deformation with respect to temperature change, and excellent mechanical properties and heat shock resistance are excellent. Has an effect.

(A), (B), and (C) of FIG. 1 are respectively a perspective view of a metal base material of Example 1, a view of the metal base material of Example 1 viewed from above, and a through hole. It is a typical top view. 2A, 2B, and 2C are respectively a perspective view of a composite molded product, an AA end view in FIG. 1B, and a BB in FIG. 1B. It is an end view. (A) and (B) of Drawing 3 are the figures which looked at the metallic substrate of Example 2 from the upper part, respectively, and the figure which looked at the metallic substrate of comparative example 1 from the upper part, respectively.

  Hereinafter, the present invention will be described based on examples with reference to the drawings. Prior to that, an evaluation method will be described.

(1) Measurement of crystallinity of crystalline thermoplastic resin A 10 mg sample was cut out from the first resin layer formed on the flat portion of the base material, and the resulting sample was subjected to PERKIN-ELMER DSC-II. When the temperature was raised from 30 ° C. to 210 ° C. at a rate of 10 ° C./min, only an endothermic peak was observed around 164 ° C. The degree of crystallinity (DOC ₁ , DOC ₂ ) for each of the composite molded product after being taken out from the mold after molding and the composite molded product after being subjected to crystallization treatment from the heat quantity of the endothermic peak and the theoretical heat of fusion. Asked.

(2) Heat shock resistance test About the composite molded products of Examples 1 to 3 and Comparative Example 1 after the crystallization treatment obtained by the above method, a heat shock resistance tester (manufactured by Espec Corp., model: The test was performed according to TSA-100S). The heat shock resistance test was conducted at a temperature of 130 ° C. for 1 hour, then at −40 ° C. for 5 seconds, held for 1 hour, and further at a temperature of 130 ° C. for 5 seconds. Each one of the above was regarded as one cycle, and this was carried out for 100 cycles. For each example, five composite molded articles were tested, and the composite molded articles after the test were visually observed to determine the number of composite molded articles in which cracks occurred.

Using a vertical injection molding machine (manufactured by Nissei Co., Ltd., model: TH60-R5VSE), the size shown in FIG. 1A as a perspective view is 70 mm × 80 mm × 10 mm and 0.5 mm in thickness. As shown in (B) and (C), five oval through holes 4, 4 ′, 4 ″, 5, 5 ′ (L _L = 16 mm, L _S = 4 mm) are formed in the plate-like portion 2. A die-cast base material 1 made of rectangular parallelepiped zinc (linear expansion coefficient: 3.3 × 10 ⁻⁵ / ° C.) provided in a cavity provided in an injection mold. At 200 ° C, mold temperature 60 ° C, molten polyacetal resin (product name: Iupital (registered trademark) F20-03, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) via a molten resin injection part opened in the cavity , linear expansion coefficient: 11 × 10 ^-5 / ° C) in the cavity to Out, by insert molding, perspective view in (A) of FIG. 2, FIG. 2 (B), to prepare a composite molded article 6 which shows an end view in (C). The thickness of the 1st resin layer 7 was 2 mm, and the thickness of the 2nd resin layer 8 was also 2 mm. The obtained composite molded article 6 was taken out of the mold, allowed to stand at room temperature for 12 hours, and then measured for the crystallinity DOC ₁ of the crystalline thermoplastic resin by the method described in (1) above. DOC ₁ was 40%. Reference numeral 10 is a trace of the molten resin injection portion left in the substantially central portion of the first resin layer 7.

Subsequently, the composite molded article was subjected to crystallization treatment in an air atmosphere at a temperature of 100 ° C. for 1 hour. When the crystallization degree DOC ₂ of the crystalline thermoplastic resin was measured by the method described in (1) above for the obtained composite molded article after crystallization treatment after standing at room temperature for 12 hours, the crystallization degree DOC ₂ was 42%. Moreover, the length of the space | gap formed in the long-axis both ends of the through-hole was 0.03 mm combining both ends. When the obtained composite molded article after the crystallization treatment was subjected to a heat shock resistance test by the method described in (2) above, the number of composite molded articles in which cracks occurred was 0 out of 5. It was.

In Example 1, as shown in FIG. 3A, the oval through holes are only 4, 4 ″, 4 ″ (L _L = 16 mm, L _S = 4 mm), and the molten resin injection portion trace 10 is formed. A composite molded product 6 was produced in the same manner as in Example 1 except that the method was as shown in FIG. The thickness of the 1st resin layer 7 was 2 mm, and the thickness of the 2nd resin layer 8 was also 2 mm. Retrieve this composite molded from the mold, allowed to stand at room temperature for 12 hours, the (1) was measured for the crystallinity of DOC ₁ of crystalline thermoplastic resins by the method described in, crystallinity DOC ₁ is 40%.

Subsequently, the obtained composite molded article was crystallized in an air atmosphere at a temperature of 100 ° C. for 1 hour. When the crystallization degree DOC ₂ of the crystalline thermoplastic resin was measured by the method described in (1) above for the obtained composite molded article after crystallization treatment after standing at room temperature for 12 hours, the crystallization degree DOC ₂ was 42%. Moreover, the length of the space | gap formed in the long-axis both ends of the through-hole was 0.03 mm combining both ends. When the obtained composite molded article after the crystallization treatment was subjected to a heat shock resistance test by the method described in (2) above, the number of composite molded articles in which cracks occurred was 0 out of 5. It was.

A composite molded product 6 was produced in the same manner as in Example 1 except that the size of the oval through hole was set to L _L = 8 mm and L _S = 4 mm. The thickness of the 1st resin layer 7 was 2 mm, and the thickness of the 2nd resin layer 8 was also 2 mm. Retrieve this composite molded from the mold, allowed to stand at room temperature for 12 hours, the (1) was measured for the crystallinity of DOC ₁ of crystalline thermoplastic resins by the method described in, crystallinity DOC ₁ is 40%.

Subsequently, the obtained composite molded article was crystallized in an air atmosphere at a temperature of 100 ° C. for 1 hour. When the crystallization degree DOC ₂ of the crystalline thermoplastic resin was measured by the method described in (1) above for the obtained composite molded article after crystallization treatment after standing at room temperature for 12 hours, the crystallization degree DOC ₂ was 42%. Further, the length of the gap formed at both ends of the long axis of the through hole was 0.015 mm in total at both ends. When the obtained composite molded article after the crystallization treatment was subjected to a heat shock resistance test by the method described in (2) above, the number of composite molded articles in which cracks occurred was 0 out of 5. It was.

The crystallization treatment conditions for the composite molded article were the same as in Example 1 except that the conditions were 2 hours at 120 ° C. in an air atmosphere. The degree of crystallinity DOC ₁ after removing the mold was 40%. The crystallinity DOC ₂ after the crystallization treatment was 44%. Moreover, the length of the space | gap formed in the long-axis both ends of a through-hole was 0.035 mm in total for both ends. When the obtained composite molded article after the crystallization treatment was subjected to a heat shock resistance test by the method described in (2) above, the number of composite molded articles in which cracks occurred was 0 out of 5. It was.
[Comparative Example 1]

In Comparative Example 1, a composite molded article was produced in the same manner as in Example 1 except that the shape of the through hole 24 was a circle (diameter 4 mm) (see FIG. 3B). The thickness of the first resin layer was 2 mm, and the thickness of the second resin layer was 2 mm. Retrieve this composite molded from the mold, allowed to stand at room temperature for 12 hours, the (1) was measured for the crystallinity of DOC ₁ of crystalline thermoplastic resins by the method described in, crystallinity DOC ₁ is 40%.

Subsequently, the obtained composite molded article was crystallized in an air atmosphere at a temperature of 100 ° C. for 1 hour. When the crystallinity DOC ₂ of the crystalline thermoplastic resin was measured by the method described in (1) above for the obtained composite molded article after crystallization treatment after standing at room temperature for 12 hours, the crystallinity DOC ₂ was 42%. The obtained composite molded article after the crystallization treatment was subjected to a heat shock resistance test according to the method described in (2) above. As a result, the composite hole was cracked because the through hole 24 was shaped into a circle. The number of products was 5 out of 5.

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Plate-shaped part, 3 ... Side wall, 4, 4 ', 4 ", 5, 5' ... Through-hole, 6 ... Composite molded article, 7 ... 1st resin layer, 8 ... 2nd resin layer, 9 ... Resin connecting part, 10 ... Molten resin injection part trace, 11 ... Mounting part, 12 ... Air gap, 24 ..Through holes

Claims (8)

(A) Injecting a substantially box-shaped metal base material comprising a plate-like portion having a plurality of through-holes, at least a part of which has a long hole shape, and a side wall provided at an edge of the plate-like portion. After mounting in the mold cavity,
(B) By injecting a crystalline thermoplastic resin into the cavity, and forming a crystalline thermoplastic resin layer straddling a plurality of through-holes and continuing on both sides of the plate-like portion via the through-holes , Producing a composite molded product of the base material and the crystalline thermoplastic resin layer,
(C) After taking out the composite molded product from the mold, the crystalline thermoplastic resin is crystallized so that the crystallinity of the crystalline thermoplastic resin is 1% or more higher than the crystallinity after taking out the mold. Therefore, a method for producing a composite molded product, characterized in that the crystalline thermoplastic resin in the through hole having a long hole shape is shrunk in the long axis direction of the long hole to form a void at the end of the long axis .   The through hole having a long hole shape is provided so that a major axis thereof is substantially along a line connecting the molten resin injection portion trace and the through hole in the case of a composite molded product. The manufacturing method of the composite molded product of description. Through holes having a long hole shape, characterized in that the ratio of the length of the major axis (L _L) and the length of the minor axis _{(L S) (L L /} L S) is 2 or more The manufacturing method of the composite molded product of Claim 1 or Claim 2.   4. The crystallization treatment according to claim 1, wherein the crystallization treatment is performed in an air atmosphere at a temperature of 60 ° C. to 120 ° C. for a time of 0.5 hours to 2 hours. Manufacturing method of composite molded article. When the linear expansion coefficient of the metal constituting the substrate is α _M and the linear expansion coefficient of the crystalline thermoplastic resin is α _R ,
1 × 10 ⁻⁵ / ° C ≦ α _R −α _M ≦ 15 × 10 ⁻⁵ / ° C
The method for producing a composite molded article according to any one of claims 1 to 4, wherein:   The method for producing a composite molded article according to any one of claims 1 to 5, wherein the crystalline thermoplastic resin is a polyacetal resin. (A) a substantially box-shaped metal substrate comprising a plate-like portion having a plurality of through-holes, at least a part of which is in the shape of a long hole, and a side wall provided at an edge of the plate-like portion;
(B) a composite molded article composed of a crystalline thermoplastic resin layer straddling a plurality of through-holes of the base material and continuous on both sides of the plate-like portion via the through-holes,
A composite molded article characterized in that a void is formed at the end of the long axis of a through hole having a long hole shape by crystallizing a crystalline thermoplastic resin.   The composite molded article according to claim 7, wherein the composite molded article is an electromagnetic shielding material or a magnetic shielding material.

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