JP7194872B1 - Method for manufacturing insert-molded product, method for manufacturing insert-molded product and insert-molded product with reduced distortion - Google Patents

Abstract

An object of the present invention is to provide a method for producing an insert-molded article with improved heat shock resistance without deteriorating the physical properties of the resin, an insert-molded article, and a method for producing an insert-molded article with reduced distortion. An object of the present invention is to provide a method for producing an insert-molded product by insert-molding a crystalline thermoplastic resin (A) into a heatable insert member (B), wherein the crystalline thermoplastic resin (A) is inserted into the insert member (B). After insert molding into the member (B) to form an insert crude molded product, the insert member (B) of the insert crude molded product is heated to form the crystalline thermoplastic resin (A) and the insert member (B). A method for producing an insert-molded product, which has a step of increasing the crystallinity of the crystalline thermoplastic resin (A) on the joint surface.

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an insert-molded product, an insert-molded product, and a method for manufacturing an insert-molded product with reduced distortion. The present invention relates to a method for manufacturing a reduced insert molded article.

2. Description of the Related Art In recent years, insert-molded products in which metals such as aluminum and iron are combined with resins are often used for electric and electronic equipment parts, automobile parts, and the like. Compositing with metal is advantageous from the viewpoints of strength improvement, part weight reduction, process shortening, antistatic, heat dissipation, and electromagnetic wave shielding properties.

On the other hand, composite insert-molded products are damaged due to strain caused by the difference between the linear expansion of the metal and the linear expansion of the resin (heat shock fracture) when the temperature becomes high when the current is applied or when the environmental temperature changes greatly, such as in automobiles. There was something I ended up doing.

In order to improve it, a technique of increasing the bonding strength by forming unevenness on the metal surface of the insert member (Patent Document 1), or a technique of adding an elastomer to the resin has been proposed (Patent Documents 1 and 2). ).

However, these technologies require advanced surface treatment on the metal surface, so simply molding resin on metal members that have been subjected to such surface treatment will always ensure a strong and stable bond strength. has an uneasy side. In addition, since adding an elastomer to a resin lowers the original physical properties of the resin, there is a limit to the amount of addition.

JP 2018-58231 A JP 2020-143193 A JP 2014-136407 A

An object of the present invention is to provide a method for producing an insert-molded product with improved heat shock resistance without stably degrading the physical properties of the resin, an insert-molded product, and a method for producing an insert-molded product with reduced distortion. be.

An object of the present invention is to provide a method for producing an insert-molded article with improved heat shock resistance without deteriorating the physical properties of the resin, an insert-molded article, and a method for producing an insert-molded article with reduced distortion.

The objects of the invention have been achieved by:

1. A method for producing an insert-molded product in which a heatable insert member (B) is insert-molded with a crystalline thermoplastic resin (A), wherein the crystalline thermoplastic resin (A) is insert-molded into the insert member (B). After forming the insert crude molded product, the insert member (B) of the insert crude molded product is heated, and the crystallinity at the joint surface between the crystalline thermoplastic resin (A) and the insert member (B) A method for producing an insert-molded product, comprising a step of increasing the crystallinity of a thermoplastic resin (A).
2. 2. The method for producing an insert-molded product according to 1 above, wherein the insert member (B) is selected from iron, copper, aluminum, magnesium, titanium, stainless steel and carbon materials.
3. An insert-molded product obtained by insert-molding a crystalline thermoplastic resin (A) into a heatable insert member (B), which is an insert-molded product obtained by heating the insert member (B), wherein the insert-molded product In the joint surface between the crystalline thermoplastic resin (A) and the insert member (B), the degree of crystallinity of the skin layer present on the joint surface of the crystalline thermoplastic resin (A) is determined by the degree of crystallinity of the insert crude molded product. An insert-molded article having a crystallinity higher than that of the skin layer present on the joint surface.
4. A method for producing a strain-relaxed insert-molded product produced by insert-molding a crystalline thermoplastic resin (A) into a heatable insert member (B), the method for producing the insert-molded product comprising: A method for manufacturing an insert-molded product with strain relief, comprising the step of heating the insert member (B).

According to the present invention, it is possible to provide a method for producing an insert-molded product with improved heat shock resistance without deteriorating the physical properties of the resin, an insert-molded product, and a method for producing an insert-molded product with reduced distortion.

It is a photograph showing an insert member and an insert-molded product of the present invention. FIG. 4 is a diagram showing a state in which the insert crude molded product of the present invention is heated by an electromagnetic induction device; FIG. 2 is a diagram showing a test piece for detecting the state of crystallization of the insert-molded product of the present invention; 1 is a polarizing microscope photograph showing the state of crystallization of a roughly insert-molded article and an insert-molded article of the present invention. It is a figure which shows the direction of the distortion of the insert-molded article of this invention. It is a graph which shows the distortion of the insert rough molding of this invention, and an insert molding.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

The present invention is a method for producing an insert-molded product in which a heatable insert member (B) is insert-molded with a crystalline thermoplastic resin (A), wherein the crystalline thermoplastic resin (A) is used as the insert member (B ) to form an insert crude molded product, the insert member (B) of the insert crude molded product is heated, and the joining surface between the crystalline thermoplastic resin (A) and the insert member (B) A method for producing an insert-molded product, comprising the step of increasing the crystallinity of the crystalline thermoplastic resin (A) in .

<Crystalline thermoplastic resin (A)>
The crystalline thermoplastic resin (A) of the present invention is not particularly limited. Resins, polyimide resins, polyetherketone resins, polyetheretherketone resins, liquid crystalline resins, fluororesins, thermoplastic elastomers, various biodegradable resins, etc., and are composed of two or more types of crystalline thermoplastic resins. may

The crystalline thermoplastic resin (A) of the present invention may contain components other than the crystalline thermoplastic resin as long as the effects of the present invention are not impaired. Components other than crystalline thermoplastic resins include, for example, amorphous thermoplastic resins, reinforcing agents such as inorganic fillers, stabilizers such as antioxidants, flame retardants, coloring agents (dyes, pigments, etc.), and lubricants. Additives such as

The crystalline thermoplastic resin (A) of the present invention may contain carbon black, carbon fiber, etc. for coloring, antistatic properties, imparting electromagnetic wave shielding properties, and the like. However, if a large amount is added, when the insert member (B) is heated by electromagnetic induction, the crystalline thermoplastic resin (A) may also be heated at the same time. 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less.

<Insert member (B)>
The heatable insert member (B) of the present invention is not particularly limited as long as it is heatable, but is preferably a metal containing an alloy or a carbon material.
The metal is preferably selected from iron, copper, aluminum, magnesium, titanium and stainless steel, nickel, chromium, platinum, gold and lead. Examples of carbon materials include carbon and graphite.

<Manufacturing method of insert molded product>
In the method for producing an insert-molded product of the present invention, first, a rough insert-molded product is produced before the insert member (B) portion is heated. The insert crude product can be formed by a normal insert molding method. In general, the insert member (B) is provided in a mold and formed by injection molding the crystalline thermoplastic resin (A) there. The blank insert is removed from the mold and allowed to cool. In the present invention, the insert member (B) of the insert crude molded product is then heated.

<Method for heating insert member (B)>
As a method for heating the insert member (B) of the insert crude molded product, the insert member (B) itself may be heated, or a heat source separate from the insert member (B) may be brought into contact with the insert member (B). Also good.

The insert member (B) may be heated with a CO ₂ laser or the like. Also, before insert molding, the insert member (B) is coated with a laser absorber or a laser absorber sheet is attached, and after the insert rough molded product is created, the crystalline thermoplastic resin (A) has a wavelength that transmits (for example, The insert member (B) may be heated by irradiating the thermoplastic resin (A) portion with a laser in the near-infrared region.

From the viewpoint of promoting crystallization of the crystalline thermoplastic resin on the joint surface while suppressing deformation of the insert-molded product, this method preferentially heats the joint surface rather than the entire insert-molded product. is preferred.

In addition, it is preferable to use electric heating as a heating means from the viewpoint of ease of installation on the insert crude molded article and ease of temperature control. Examples of electric heating include direct resistance heating and electromagnetic induction heating.

In direct resistance heating, heating can be performed by applying a direct current to the insert member (B) in the insert crude molded product as a heating element, or by connecting an arbitrary heating element and the insert member (B) and applying a direct current. If it is difficult to secure a contact point due to the shape of the insert member (B), any heating element heated by direct resistance heating may be brought into contact with the insert member (B) to heat the insert member (B) by thermal conduction.

In electromagnetic induction heating, the insert member (B) is installed in the heating coil, and heating can be performed by the generated eddy current and the electrical resistance of the metal. Electromagnetic induction heating is particularly preferred because it can be heated in a short period of time, is easy to control, and is less affected by radiant heat.

FIG. 2 shows the state of heating by electromagnetic induction in the present invention. The insert crude molding is placed in an electromagnetic induction device and heated by electromagnetic induction. A portion of the insert member (B) is strongly heated by electromagnetic induction. Although the entire crystalline thermoplastic resin (A) is not heated, the joint with the insert member (B) is heated by heat conduction, and the crystallization of the crystalline thermoplastic resin (A) is promoted at the joint. Shrink.

For example, when the insert crude molding is heated by an indirect resistance heating method such as a constant temperature bath, the entire insert crude molding is heated. The resulting strain may cause deformation or cracking. Further, when direct flame is used, if the insert member (B) is made of a carbon material, the radiant heat may heat the resin portion other than the joint portion, or erroneously ignite.

As for the heating conditions by electric heating, a certain amount of trial and error is required to derive the electric heating conditions that maximize crystallization. can be heated at the same time.

The heating temperature is preferably higher than the glass transition point of the crystalline thermoplastic resin (A) and lower than the crystalline melting point. In order to promote crystallization at the joint before the crystalline thermoplastic resin (A) solidifies, it is preferable to cool the joint at room temperature instead of quenching.

<Effect of Heating Insert Member (B)>
Since the joint surface of the crystalline thermoplastic resin (A) with the insert member (B) is cooled most quickly when forming the insert crude molded product, the joint surface is called a skin layer, so that the joint surface has a thickness of 5 to 5. A layer having a thickness of the order of 150 μm and having a lower crystallinity than the inside of the molding is formed.

The thickness of the skin layer varies slightly depending on the type of resin and molding conditions, but the formation of the skin layer is more crystalline in the insert member (B) than in the insert member (B) even if the insert member (B) is preheated during injection molding. This is an unavoidable phenomenon because it has a higher thermal conductivity than the thermoplastic resin (A) and is cooled faster by the mold.

The degree of crystallinity of the skin layer is lower than the degree of crystallinity inside the molded article, and is 5 to 95% of the degree of crystallinity inside the molded article. Crystallinity can be measured by microscopic IR, X-ray diffraction, density, and the like.

As a result of promoting the crystallization of the joint surface by heating the insert member (B) of the present invention, the strain remaining in the crude insert molding is relaxed at the same time, and the insert molding is less likely to break due to heat shock. .

FIG. 4 is a polarizing microscope photograph from the observation direction shown in FIG. (a) is an insert-molded product, and (b) is an insert-molded product that has undergone a heating process using electromagnetic induction. In (a), which is a crude insert molded product, the presence of a skin layer of about 120 μm with a low degree of crystallinity of the crystalline thermoplastic resin (A) can be seen around the joint surface of the insert member (B). On the other hand, in (b), it can be seen that the skin layer with a low degree of crystallinity has disappeared.

When the entire insert member (B) is heated in a constant temperature bath, etc., instead of heating only the insert member (B) by electromagnetic induction heating, the skin layer disappears when heated to near the melting point, but the entire insert crude product is heated. It softens and deforms under its own weight. Moreover, the skin layer does not disappear when heated to a temperature that does not cause deformation.

Therefore, even if the crude insert molded product has undergone some heating process, it is possible to confirm whether or not only the insert member (B) has undergone the heating process by checking the presence or absence of the skin layer at the contact portion between the insert member and the resin. be able to.

In the present invention, the fact that the thickness of the skin layer in the molded article is thinner than the thickness of the skin layer in the crude molded article also means that the degree of crystallinity is increased.

FIG. 5 is a photograph showing the state of measuring the distortion of an insert-molded product. A gauge (one gauge length 2 mm (radius D of the entire strain gauge = 5.13 mm), "FRS-2-11", manufactured by Tokyo Sokki Kenkyusho Co., Ltd.). The strain gauge was connected to a data logger ("UCAM-60B", manufactured by Kyowa Dengyo Co., Ltd.) to measure the amount of strain released from the resin molded article when a hole of 0.2 mm was made in the thickness direction. The measurement is performed in an atmosphere of 23° C. and 50% RH.

FIG. 6 is a pie chart of the cut release strain distribution showing the results of measuring the strain according to FIG. (a) is the distortion of the insert-molded product, and (b) is the distortion of the insert-molded product that has undergone the heating process by electromagnetic induction. It can be seen that the strain is relaxed by about 0.1%. The insert molded product has shrunk by 0.02 mm from the insert crude molded product.

So far, we have explained that heating by electric heating is performed in addition to the process of manufacturing from a crude insert molded product, but even for other insert molded products, a layer with a low degree of crystallinity on the joint surface by a polarizing microscope etc. In the case of an insert-molded article in which a is present, the distortion of the insert-molded article can be relaxed by heating by electromagnetic induction.

In addition, if the entire insert member (B) is heated in a constant temperature bath or the like instead of heating only the insert member (B) by electric heating, the entire resin portion of the insert member will shrink. The shrinkage difference increases the strain, and the heat shock resistance is rather lowered.

When the entire insert rough molded product is heated in a constant temperature bath, etc., the crystallinity of the skin layer at the contact part of the insert member and the resin and the skin layer at the part not in contact with the insert member will be almost the same, but electromagnetic induction etc. When only the insert member (B) is heated by , the skin layer at the contact portion between the insert member and the resin has a higher degree of crystallinity than the skin layer at the non-contact portion. For example, in the case of polyacetal resin, the degree of crystallinity can be compared by cutting only the skin layer and measuring wide-angle X-ray diffraction (WAXD).

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these.

DURACON (registered trademark) M90-44 (POM resin manufactured by Polyplastics Co., Ltd.) as the crystalline thermoplastic resin (A) was added to the insert member (B) (90 × 20 × 2 mm, steel material) shown in FIG. Injection molding was performed at a cylinder temperature of 200° C. and a mold temperature of 80° C. to produce 12 crude insert moldings (90×24×6 mm) shown in FIG. 6 pieces of the insert crude molded product were heated by electromagnetic induction at 500 W for 4 seconds using a UHT-500 manufactured by Seidensha Denshi Kogyo Co., Ltd. in an environment of 23 ° C. × 50% RH. formed.
The following heat shock test was performed on the insert-molded specimen.

After the insert member (B) was removed, the degree of crystallinity of the resin joint was measured by X-ray diffraction for each of the roughly insert-molded product and the insert-molded product thus prepared. The skin layer of the insert-molded product was 60%, whereas the skin layer of the insert-molded product could not be confirmed, so the outermost layer was measured to be 65%.

Heat shock conditions: One cycle is −40° C. for 1 hour and then 120° C. for 1 hour.

A test piece was taken out every 10 cycles, and the presence or absence of cracks was visually observed. As a result, the insert-molded product cracked after 10 cycles, but the insert-molded product did not crack even after 500 cycles.

1 insert member (B)
2 Crystalline thermoplastic resin (A)
3 Observation direction

Claims (5)

A method for producing an insert-molded product in which a heatable insert member (B) is insert-molded with a crystalline thermoplastic resin (A), wherein the crystalline thermoplastic resin (A) is insert-molded into the insert member (B). After forming the insert crude molded product, the insert member (B) of the insert crude molded product is heated, and the crystallinity at the joint surface between the crystalline thermoplastic resin (A) and the insert member (B) a step of increasing the crystallinity of the thermoplastic resin (A) to eliminate the skin layer of the crystalline thermoplastic resin (A) on the joint surface ;
In the heating, the crystalline thermoplastic resin (A) on the joint surface is heated, and the entire crystalline thermoplastic resin (A) is not heated,
The method for producing an insert-molded product, wherein the heating temperature is equal to or higher than the glass transition point of the crystalline thermoplastic resin (A) and equal to or lower than the crystalline melting point . The method for manufacturing an insert-molded product according to claim 1 , wherein the heating is performed by electromagnetic induction heating. 3. The method for producing an insert-molded product according to claim 1, wherein said insert member (B) is selected from iron, copper, aluminum, magnesium, titanium, stainless steel and carbon materials. A method for producing a strain-relaxed insert-molded product produced by insert-molding a crystalline thermoplastic resin (A) into a heatable insert member (B), the method for producing the insert-molded product comprising: a step of heating the insert member (B) to eliminate the skin layer of the crystalline thermoplastic resin (A) on the joint surface between the crystalline thermoplastic resin (A) and the insert member (B); ,
In the heating, the crystalline thermoplastic resin (A) on the joint surface is heated, and the entire crystalline thermoplastic resin (A) is not heated,
A method for producing a strain-relaxed insert-molded article , wherein the heating temperature is equal to or higher than the glass transition point of the crystalline thermoplastic resin (A) and equal to or lower than the crystalline melting point . The method for manufacturing an insert-molded product according to claim 4 , wherein the heating is performed by electromagnetic induction heating.

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