JPH0269218A - Insert blow molding method - Google Patents

Abstract

PURPOSE:To join an insert to a polyamide resin parison by blow molding and realize a joining area, through which no air or the like leaks, by a method wherein at least either one of the insert and the parison is made of polymer alloy of polyamide resin, which is blended with polyphenylene ether resin modified by polystyrene. CONSTITUTION:An insert 10 is a hollow tubular body having an annular flange- like projecting part 12 at one end on its outer surface and is formed by injecting polymer alloy of polyamide resin blended with polyphenylene ether resin modified by polystyrene as raw material for use as the insert. On the other hand, as the resin consisting of a parison (a molded item 20), the resin, which is the same one consisting of the insert, is empolyed and extruded in the form of the parison by an extruder for blow molding. Split molds to be use have cavities, by which a hollow tubular body is molded, on their inner surface and, at the same time, recessed parts, in which the insert is installed, at their predetermined positions so as to perform blow molding under the condition that the respective insert and parison are employed in order to realize a blow molded item with integral insert.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method for molding internally hollow molded products such as air ducts for automobiles, and in particular to a blow molding method for hollow molded products mainly made of polyamide resin. Regarding.

(Prior Art) In recent years, the uses of plastics have been increasingly expanded due to their improvements, and various plastics are used in the field of the automobile industry using various molding methods.

Among them, plastics with excellent physical properties called engineering plastics are being used for engine parts due to their heat resistance. As a solution, attempts have been made to use blow-molded products of polyamide resin, which has excellent oil resistance, especially polyamide resin mixed with glass fibers to increase mechanical strength, as air supply pipes to engines.

By the way, the intake pipe is often of a branched structure with branch pipes for distributing the intake air to each cylinder or connecting it to a turbocharger, etc. Therefore, even if the intake pipe is blow molded, it is necessary to A branch pipe molded by injection molding or the like from the same polyamide resin as the constituent resin is placed in a predetermined split mold as an insert, and a vanoson made of a melt of the glass fiber-containing polyamide resin is introduced into the mold. , blowing compressed air into the parison to expand the parison and bring it into close contact with the split mold, shaping it into a predetermined shape, and joining and fixing the branch pipe (insert) and the parison during the molding; What is being done is to integrate the two. At this time, as shown in FIG. 1, the parison (molded product 20) of the branch pipe, which is the insert 10,
The one end 11 of the insert 4, which is the joint part with the insert, may have a flange-like protrusion 12 widened on its end surface to increase the joint area of the parison, or a protrusion 13 or a protrusion 13 on the outer surface of the insert, as shown in FIG. A recess (not shown) is provided, the outer surface of which is wrapped with an expandable parison, and a portion of the blow molded product is placed on the protrusion of the insert or on the surface of the recess using molding shrinkage as the blow molded product cools. The parts are stuck together (fixed) by biting into them. At this time, in order to achieve an open welding connection between the insert and the blow molded product, the branch pipe that is the insert is preheated, and the surface of the insert is melted by the heat retained by the parison and is thermally welded to the blow molded product.
Efforts are made to improve the bonding.

(Problem to be Solved by the Invention) However, although the molded product appeared to be completely joined to the upper inserter I, a weight of 1.5 kg/kg was applied to the molded product.
When an internal pressure of am2 was applied, air leaked from the joint between the insert and the blow-molded product, and it was found that it could not be used practically as an air supply pipe to an engine.

To solve this problem, the inventors changed the shape of the insert,
Various attempts were made by changing the surface precision, preheating temperature, etc., but no reliable insert blow molded product could be obtained. The reason for this is that polyamide resin has a high melting point of over 200°C, and even if the parison has a resin temperature close to that, the insert (branch pipe) installed in the mold must be preheated to room temperature or slightly higher. Therefore, it is difficult to melt the insert surface with the heat retained by the parison, and even if the insert and the blow-molded product are made of the same or homogeneous polyamide resin, sufficient bonding (adhesion) between them cannot be achieved. It seems to be for a reason.

It is also possible to preheat the insert (branch pipe) to a temperature close to the resin temperature of the parison to achieve sufficient welding, but even if the preheating temperature of the insert could be raised to the temperature of the parison, the temperature of the insert would be close to the melting point. Because of this, it is easy to deform with a slight external force, and it may even become difficult to handle, causing 1M, and even if it can be installed in the mold, the mold will not originally shape the parison. This is because the molded product is cooled down to form a predetermined shape.
The temperature is set close to room temperature. Therefore, the high temperature insert placed in the mold is also rapidly cooled by the mold, and as mentioned above, there is a possibility that sufficient effects cannot be expected, such as insufficient adhesion at the joint.

(Means for Solving the Problem) Therefore, as a result of extensive research to solve this problem, the inventor of the present invention found that when a certain type of plastic is blended with polyamide resin, the insert (branch pipe) and polyamide resin at room temperature The inventors have discovered that the resin parison can be easily adhered to the resin parison by blow molding, and that air and the like do not leak from the adhered portion, leading to the present invention.

The gist of the present invention is to install an insert made of polyamide resin in a predetermined split mold, introduce a parison also made of polyamide resin into the split mold, and perform blow molding to combine the insert and the blow molded product. In the insert blow molding method, at least one of the insert or the parison is made of a polymer alloy of a polyamide resin blended with a polystyrene-modified polyphenylene ether resin, and blow molding is performed.

(Function) In blow molding with the above configuration, the reason why the insert and the blow molded product come into close contact is not clear, but the polystyrene-modified polyphenylene ether resin blended into the polyamide resin constituting the insert or parison is A so-called impact-resistant polystyrene resin, which is a copolymerization of styrene and the rubbery component butadiene, or a blend of polystyrene and polybutadiene, is used as the main modifying component, and the parison is one end of the insert. It is presumed that when the insert is bonded or wrapped, the rubbery component present on either surface acts like an elastic sealant on the contact surface between the insert and the blow-molded product.

In the present invention, polyamide resin refers to polyamide-6 (commonly known as nylon-6) made from ε-caprolactam.
), polyamide made from hexamethylene diamine and adipic acid - 66 (same nylon-66), other polyamide-610 (same nylon-610), polyamide-11
A wide variety of polyamide-based synthetic resins can be used, such as (the same nylon-11) and polyamide-12 (the same nylon-12), and are not limited to the examples.

Polystyrene-modified polyphenylene ether resin is a combination of polyphenylene ether containing phenylene ether as a repeating unit and polystyrene resin, particularly a so-called impact-resistant polystyrene resin containing 5 to 20 weight percent of a rubbery component such as polybutadiene. 8
Polystyrene-modified polyphenylene ether resin, commonly called modified polyphenylene oxide, is blended in a ratio of 5:15, or oligophenyl ether with a polymerization degree of 60-90 and a styrene compound in a ratio of 30-1.
It is a graft-type polystyrene-modified polyphenylene ether resin which is mainly composed of a graft copolymer obtained by graft polymerization of 80% by weight and blended with 30-120% by weight of polystyrene resin or the above-mentioned impact-resistant polystyrene resin.

This polyamide resin and polystyrene-modified polyphenylene ether resin are blended at a ratio of 0 to 70:30 to form a polyamide-based polymer alloy. In addition, in order to provide the raw material for the air supply pipe to the engine, approximately 5 milled glass fibers are added to this polymer alloy.
-40 weight percent, preferably 1O-30iffi
Preferably, it is incorporated in a percentage to improve mechanical strength and thermal properties. In addition, as shown in the example, inserter I
-Alternatively, at least one of the parisons may be composed of a polyamide resin blended with the polystyrene-modified polyphenylene ether resin.

(Example) The present invention will be explained below based on examples.

FIG. 1 is a cross-sectional example of an integrally molded insert according to the present invention, and the insert 10 is a hollow tubular body having a diameter of 20 mm and having an annular flange-like protrusion 12 on the outer surface of one end. For comparison, the inserts were injection molded using conventional polyamide resins such as polyamide-6, polyamide-66, and their glass fiber-containing resins, and a polymer alloy according to the present invention, which is a blend of polyamide resin and polystyrene-modified polyphenylene ether resin. and used it as an insert. The latter polymer alloy according to the present invention is a mixture of the former polyamide-6 and polyamide-66 with polystyrene-modified polyphenylene ether resin in a ratio of 1:1.
These materials were blended in the following proportions, and milled glass fiber was further mixed in at approximately 30% by weight in each of the materials.

On the other hand, as the resin constituting the parison (molded product 20), the same constituent resin as that of the insert was used, and each of these was extruded into a parison of about 30 mmφ using an extruder and subjected to blow molding.

The split mold used had a cavity forming a hollow tubular body of about 50 mm in diameter on its inner surface, and a recess in which the insert could be placed at a predetermined position.

Blow molding is performed using each insert and parison, and this insert-integrated blow molded product has a weight of 1.5 kg/
An internal pressure of am2 was applied, and an air leak test was conducted at the insert contact area underwater.

The test results are shown in Table-1. Note that the joint between the insert 10 and the molded product 20 may be such that the protrusion 13 on the outer surface of the insert is covered with the molded product, as shown in FIG. In the molded product integrally molded in this way, the molded product partition wall 21 at the joint is removed from the other end of the tubular body, which is the insert, using a hole-drilling device such as a reamer, and the molded product partition wall 21 at the joint portion is removed, and the structure is communicated with the inside of the insert. .

(Effects) As described above, the present invention comprises an insert made of a polymer alloy blended with a polyamide resin and a polystyrene-modified polyphenylene ether resin or a conventional polyamide resin, and a parison made of the same polymer alloy or a conventional polyamide resin, In addition, by constructing at least either the insert or the parison from a polyamide resin blended with polystyrene-modified polyphenylene ether resin, insert blow molding with improved airtightness (sealability) at the joint between the insert and the molded product is possible. This is what became. In particular, it expands the use of polyamide resin blow molded products under extremely harsh conditions, such as air supply pipes around automobile engines, and also expands the use of polyamide resin blow molded products in various types of complex hollow parts that were conventionally made of cast iron or iron pipes. This allows components to be constructed from lightweight polyamide resin.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an example of an insert-integrated blow molded product, and FIG. 2 is a sectional view similar to FIG. 1 showing another embodiment.

Claims (1)

[Claims] 1) An insert made of polyamide resin is installed in a predetermined split mold, a parison also made of polyamide resin is introduced into the split mold, and compressed air is blown into the parison to perform blow molding. In an insert blow molding method in which a parison is expanded and shaped into a predetermined shape and the insert and the blow molded product are integrated, at least one of the insert or the parison is made of a polyamide resin blended with a polystyrene-modified polyphenylene ether resin. An insert blow molding method characterized by comprising a polymer alloy of. 2) The insert blow molding method according to claim 1, wherein the polymer alloy contains glass fibers.