JPH07107131B2 - Manufacturing method of polyarylene sulfide resin foam molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a polyarylene sulfide resin foamed molded product. More specifically, the present invention relates to a production method for obtaining a foamed molded product that has small molding shrinkage, warpage, sink marks, etc., has good dimensional accuracy, is lightweight, and retains the excellent properties of polyarylene sulfide resin.

[Conventional technology and its problems]

Polyarylene sulfide resins, typified by polyphenylene sulfide resins, have excellent mechanical properties, heat resistance, chemical resistance, and excellent flame retardancy. Therefore, they are materials for electronic and electrical equipment parts, and transportation equipment such as automobiles. Widely used as parts materials, parts parts for chemical equipment, etc.

In recent years, in these fields, weight reduction of equipment has become an important issue, and it is also necessary to reduce the weight of the resin molded product, which is a component of the equipment, without impairing the excellent characteristics originally possessed by the resin. Are increasing in demand.
At the same time, there is an increasing demand for molded products with small warpage and sink marks and good dimensional accuracy.

On the other hand, the conventionally known method cannot simultaneously satisfy such requirements. That is, in order to meet the demand for improving dimensional accuracy such as warpage and sink marks, an inorganic filler is used as
In particular, it is common to mix a large amount of a fibrous filler and a plate-like or powder-like filler, but this method cannot meet the demand for weight reduction because the specific gravity of the resin increases, and The orientation of the fibrous filler causes directionality, and improvement in sink marks, warpage, etc. was not always sufficient.

In addition, in order to reduce the weight, a method of blending a resin with an inorganic hollow body such as glass balloon is generally used. However, since the material itself forming the hollow body has a large specific gravity, it is hollowed out. However, it has a considerable specific gravity, and even if it is blended with a resin, not only the expected weight reduction cannot be achieved, but also the characteristics such as mechanical strength are significantly deteriorated.

As described above, it is possible to meet the demand for a molded product that is light in weight without impairing the excellent properties originally possessed by the polyarylene sulfide resin, and that has good dimensional accuracy with less warpage, sink marks, etc., by a conventionally known method. However, the improvement was desired.

[Means for Solving the Problems]

In order to obtain a polyarylene sulfide resin molded product that is lightweight and has good dimensional accuracy, the present inventors have made diligent studies from the viewpoint of foam molding, and found that a specific foaming agent and inorganic filling as desired. The inventors have found that a molded article obtained by molding a polyarylene sulfide resin foam molding material containing an agent satisfies the above-mentioned object, and arrived at the present invention.

(A) polyarylene sulfide resin (B) selected from the group consisting of azo compounds, nitroso compounds, sulfonyl hydrazide compounds, sulfonyl semicarbazide compounds, heterocyclic nitrogen-containing compounds, carbonate compounds and carboxylate compounds 1
From 0.01 to 5% by weight (in all molding materials) of a foaming agent having one or more kinds of decomposition and foaming temperatures of 140 to 350 ° C (in all molding materials) (C) from inorganic filler in 0 to 80% by weight (in all molding materials) The present invention relates to a method for producing a foam-molded article, which comprises subjecting the polyarylene sulfide resin foam-molding material described above to injection molding.

In the present invention, the base resin (A) is a polyarylene sulfide resin, and contains 70 mol% of repeating units represented by the structural formula-(Ar-S)-(where Ar is an aryl group).
The polymer contained above, the typical substance of which is the structural formula- (Ph
It is a polyphenylene sulfide (hereinafter, abbreviated as PPS) having a repeating unit represented by -S)-(where Ph is a phenyl group) of 70 mol% or more. Above all, the temperature is 310 ℃,
Melt viscosity of 10 to 20 measured under shear rate of 1200 / sec
Those of 000 poise, especially in the range of 100 to 5000 poise, are suitable.

Polyarylene sulfide is generally known to have a substantially linear and branched molecular structure having no crosslinked structure and one having a branched or crosslinked structure according to the production method thereof. The above is also effective, and may be a copolymer or mixture of both. However, it is more effective to mainly use a linear structure having no branch.

Preferred PPS polymers for use in the present invention have para-phenylene sulfide units as repeating units. Is 70 mol% or more, more preferably 80 mol% or more. If this repeating unit is less than 70 mol%, the crystallinity, which is a characteristic of a crystalline polymer, tends to be low, and sufficient strength may not be obtained, and the toughness tends to be poor.

Further, the PPS polymer used in the present invention may contain less than 30 mol% of other copolymerized constitutional units, for example, metaphenylene sulfide units. Diphenyl ketone sulfide unit Diphenylene Sulfon Sulfide Unit Diphenyl sulfide unit Diphenyl ether sulfide unit 2,6-naphthalene sulfide unit Trifunctional unit And so on. Of these, the trifunctional unit content is preferably 1 mol% or less from the viewpoint of not impairing crystallinity.

Particularly as the PPS polymer of the present invention, a repeating unit A linear PPS homopolymer consisting of paraphenylene sulfide and a repeating unit consisting of paraphenylene sulfide Repeating unit consisting of 70 to 95 mol% and metaphenylene sulfide, A linear structure PPS block copolymer composed of 5 to 30 mol% is particularly preferably used.

Next, in the present invention, as the component (B), the decomposition temperature is 14
A foaming agent at 0 to 350 ° C is used.

Since the base material resin, polyarylene sulfide resin, has a high molding processing temperature, if the decomposition temperature of the foaming agent is lower than 140 ° C., the foaming agent is easily decomposed at the time of molding, and the generated gas escapes. For this reason, it is difficult to control the molding, and the quality of the obtained molded product also varies greatly. On the contrary, when the decomposition temperature of the foaming agent is higher than 350 ° C., molding at a higher temperature is required, which causes problems such as decomposition or discoloration of the base resin and a long molding cycle. The preferred decomposition temperature of the blowing agent is 180-300 ° C.

In terms of chemical structure, a foaming agent selected from azo compounds, nitroso compounds, sulfonyl hydrazide compounds, sulfonyl semicarbazide compounds, heterocyclic nitrogen-containing compounds, carbonate compounds and carboxylate compounds is used. Examples of such foaming agents include azodicarbonamide, barium azodicarboxylate, dinitrosopentamethylenetetramine, 4,4′-oxy-bis-
(Benzenesulfonyl) hydrazide, 3,3'-disulfone hydrazide diphenyl sulfone, trihydrazine-S
-Triazine, 5-phenyltetrazole, calcium salt of 5-phenyltetrazole, diisopropylhydrazodicarboxylate and the like. With a foaming agent,
Urea-based, organic acid-based, and metal salt-based foaming aids can be used in combination. Further, the compounding amount of the foaming agent is 0.01 to 5% by weight in the whole molding material. If the amount is less than 0.01% by weight, a sufficient foaming effect cannot be obtained, and conversely, if the amount is more than 5% by weight, a large amount of gas is generated by decomposition, which makes it difficult to control molding. Preferably 0.05 to 4% by weight, more preferably 0.1 to
It is 3% by weight.

In addition, although the inorganic filler (C) is not always an essential component in the present invention, a molded product excellent in performance such as mechanical strength, heat resistance, dimensional stability (deformation resistance, warpage), and electrical properties. In order to obtain the above, it is preferable to mix them, and a fibrous, powdery or plate-like filler is used for this purpose.

As the fibrous filler, glass fiber, asbestos fiber,
Inorganic substances such as carbon fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, and metal fibrous material such as stainless steel, aluminum, titanium, copper, brass, etc. Examples include fibrous substances. A particularly representative fibrous filler is glass fiber or carbon fiber. High melting point organic fibrous substances such as polyamide, fluororesin and acrylic resin can also be used.

On the other hand, as the granular filler, carbon black, graphite, silica, quartz powder, glass beads, milled glass fiber, glass balloon, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay,
Silica earth, silicates such as wollastonite, iron oxides, titanium oxide, zinc oxide, metal oxides such as alumina,
Examples thereof include metal carbonates such as calcium carbonate and magnesium carbonate, calcium sulfates, metal sulfates such as barium sulfate, silicon carbide, silicon nitride, boron nitride, and various metal powders.

Examples of the plate-like filler include mica, glass flakes, various metal foils and the like.

These inorganic fillers can be used alone or in combination of two or more. The combined use of a fibrous filler, particularly glass fiber, carbon fiber or potassium titanate fiber, with a granular and / or plate-like filler is a preferable combination particularly in terms of having both mechanical strength, dimensional accuracy and electrical properties.

When using these fillers, it is desirable to use a sizing agent or a surface treatment agent if necessary. Examples of this are functional compounds such as epoxy compounds, isocyanate compounds, silane compounds and titanate compounds. These compounds may be subjected to a surface treatment or a converging treatment in advance, or may be added at the same time when the material is prepared.

The amount of the inorganic filler used is 0 to 80% by weight, preferably 10 to 60% by weight, based on the total molding material. If it is less than 10% by weight, the mechanical strength will be slightly inferior, and if it is too large, the molding work will be difficult and the mechanical strength of the molded product will also be problematic.

Further, in the present invention, a silane compound selected from aminosilane compounds, epoxysilane compounds, mercaptosilane compounds and vinylsilane compounds as a sizing agent or surface treatment agent for the filler as described above, or 0.01 It is preferable to mix the compound in an amount of 2 wt% (in the entire forming material) not only in terms of mechanical strength, but also for performing foam molding with a stable expansion ratio.

It is also effective to add a surfactant to the molding material used in the present invention in order to enhance the stability of fine bubbles generated by thermal decomposition of the foaming agent.

The surfactant is not particularly limited, and any of cationic, anionic and nonionic surfactants can be used, and the compounding amount is preferably 0.05 to 5% by weight based on the total molding material.

Furthermore, it is also effective to add a crystal nucleating agent to the molding material used in the present invention in order to promote crystallization after the resin foamed during molding is filled in the mold. As the nucleating agent, although it partially overlaps with the above-mentioned filler, nitrides such as boron nitride, clays such as kaolin, talc and clay, metal oxides, carbonates, sulfates, silicates, organics Examples thereof include fine powders of acid salts and the like, and polymer compounds having a crosslinked or branched structure. Further, in order to increase the crystal growth rate in combination with this, it is also preferable to add a phosphate ester.

Further, the base resin of the present invention can be used in a small amount in combination with other thermoplastic resins as long as the purpose thereof is not impaired. Any other thermoplastic resin may be used as long as it is a thermoplastic resin that is stable at high temperatures. For example, aromatic polyester such as polyethylene terephthalate and polybutylene terephthalate, and aromatic polyester composed of diol or oxycarboxylic acid, polyamide, polycarbonate, ABS, polyphenylene oxide, polyalkyl acrylate, polyacetal, polysulfone, polyether sulfone, polyether. Examples thereof include imide, polyetherketone, and fluororesin. In addition, these thermoplastic resins are
It is also possible to use a mixture of two or more species.

Furthermore, the molding material used in the present invention is a known substance generally added to thermoplastic resins and thermosetting resins, that is, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents,
Flame retardants, colorants such as dyes and pigments, lubricants and the like can be appropriately added depending on the required performance.

The molding material used in the present invention is prepared by blending a polyarylene sulfide resin, a foaming agent and other components before molding, and preparing a resin composition containing all or part of components other than the foaming agent. , A method of blending a foaming agent or the other components with the foaming agent, a method of preparing a masterbatch in which a foaming agent is kneaded with a resin softening at a decomposition temperature of the foaming agent or less, and blending it with other components are adopted. can do. The point is that any preparation method may be used so that heat above the decomposition temperature is not applied to the foaming agent for a long time. In particular, a method of preparing and using a masterbatch of a foaming agent is a preferable method in terms of dispersibility and workability.

When a powdery foaming agent is used and is blended with a resin or the like to form a molding material, it is preferable that the resin is surface-coated with the foaming agent in advance.

In the present invention, injection molding is used to manufacture a foam molded article using such a resin material.

Here the expansion ratio is Is defined as

If the expansion ratio is less than 1.02, it is almost impossible to expect the weight of the molded product to be reduced and the dimensional accuracy to be improved. On the other hand, if the expansion ratio exceeds 2.0, the rigidity, strength, etc. are significantly reduced, which is not preferable, and molding control is extremely difficult.

Further, if the expansion ratio of the molded product is within the above range, the dimensional accuracy becomes extremely excellent, which is preferable, but considering the purpose of weight reduction, it is more preferable that the expansion ratio is 1.1 or more.

In the present invention, it is preferable to adjust the molding conditions as described below in order to achieve the above preferable expansion ratio by injection molding.

First, in the case where the molded body does not need to be lightened so much and only for the purpose of remarkably improving the dimensional accuracy, the molding conditions of the commonly used polyarylene sulfide resin may be applied as they are.

That is, the resin temperature is 250 ~ 360 ℃, preferably 270 ~ 3
The temperature is 40 ° C., the mold temperature is 60 to 170 ° C., preferably 100 to 160 ° C., and a molding condition such that an appropriate injection holding pressure, for example, 400 to 1000 kg / cm ² is applied can be used.

Next, when it is necessary to improve the dimensional accuracy and also reduce the weight, that is, when a foaming ratio of about 1.1 or more is required,
At resin temperature and mold temperature as above, and injection holding pressure is 300k
It is preferable to mold to an extremely small value of g / cm ² or less, more preferably 100 kg / cm ² or less, and particularly preferably substantially 0 kg / cm ² .

In addition, the weight of the molding material in the molding machine is reduced to 50% of the molding volume.
It is also preferable to set it to be about 90%. It is also effective to use a molding machine with a shaft-off nozzle.

Further, the injection speed is preferably 3 m / min. Or higher, and particularly preferably 4 m / min. Or higher. For this purpose, it is preferable to use a molding machine with a high injection rate such as a molding machine with an accumulator.

The molded product thus obtained is lightweight, has good dimensional accuracy, does not impair the excellent properties of polyarylene sulfide, and is extremely preferable.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 8 and Comparative Example 1 A pelletized polyphenylene sulfide resin (PPS resin) containing glass fibers was surface-coated with 5-phenyltetrazole and aminosilane at a ratio shown in Table 1, and injection with a shut-off nozzle was performed. A 1/4 inch thick bending test piece and 120 mm × 120 mm square flat plate (thickness 3 mm and 2 mm) were molded by a molding machine. In addition, for comparison, the same molding was carried out for those to which 5-phenyltetrazole as a foaming agent was not added.

The main molding conditions are as follows, and in addition to this, the light weight and injection holding pressure were changed as shown in Table 1.

Cylinder temperature setting; Resin temperature: about 300 ° C Mold temperature: 150 ° C Injection pressure: 1400kg / cm ² Injection speed: 4.5m / min. The test piece evaluation method is as follows.

Specific gravity; measured using a 1/4 inch thick bending test piece Foaming ratio; Flexural strength, flexural modulus; Measured according to ASTM D-790 using a 1/4 inch thickness bending test piece Shrinkage rate: Measured in the flow direction and at right angles using a flat plate of 120 mm x 120 mm x 3 mm ; When 120mm × 120mm × 2mm flat plate was used and the three corners were grounded to the plane, the remaining one point was lifted from the flat surface (when there are deformations where three points cannot be grounded) Is 2
Ground the point, and measure the remaining 2 points, whichever has the largest lift).

The results are shown in Table 1.

The mixture of Example 4 to which a surfactant was further added had almost the same average physical properties as the results shown in Table 1, but the bubbles were stable throughout the molded product, and The variation was small.

Examples 9 to 11 and Comparative Example 2 Pelletized PPS resin containing 40% by weight of glass fiber and 0.5% by weight of aminosilane, and a masterbatch in which 20% by weight of diisopropylhydrazodicarboxylate as a foaming agent was kneaded with an ABS resin. Were blended in the proportions shown in Table 2, molded according to Examples 1 to 8, and evaluated. Further, for comparison, a product containing an ABS resin containing no foaming agent was similarly evaluated.

The results are shown in Table 2.

Examples 12 to 19 and Comparative Examples 1 and 3 A PPS resin containing glass fibers was mixed with a foaming agent and a silane compound as shown in Table 3 before molding, and molded and evaluated in the same manner as in Examples 1 to 8. .

The results are shown in Table 3.

[Effects of the Invention] As apparent from the above description and Examples, the polyarylene sulfide resin foam molding material of the present invention is
It can be suitably used for foam molding, and the molded product obtained by molding this is lightweight and has small warpage, sink marks, etc.
It has good dimensional accuracy and sufficient strength, and is preferably used for applications requiring light weight and high characteristics such as electric / electronic equipment parts, transportation equipment parts, and chemical equipment parts.

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Claims (5)

[Claims] 1. (A) Polyarylene sulfide resin (B) Azo compound, nitroso compound, sulfonyl hydrazide compound, sulfonyl semicarbazide compound, heterocyclic nitrogen-containing compound, carbonate compound and carboxylate compound 1 selected from the group
From 0.01 to 5% by weight (in all molding materials) of a foaming agent having one or more kinds of decomposition and foaming temperatures of 140 to 350 ° C (in all molding materials) (C) from inorganic filler in 0 to 80% by weight (in all molding materials) A method for producing a foam-molded article, which comprises subjecting the polyarylene sulfide resin foam-molding material described above to injection molding. 2. A polyarylene sulfide resin foam molding material further comprises one or more silane compounds selected from the group consisting of aminosilane compounds, epoxysilane compounds, mercaptosilane compounds and vinylsilane compounds. The method for producing a foam-molded article according to claim 1, wherein the foamed article is contained. 3. The method for producing a foam-molded article according to claim 1, wherein the polyarylene sulfide resin foam-molding material further contains a surfactant. 4. The injection holding pressure in injection molding is 0 to 300 kg / cm.
^{2. The} method for producing a foamed molded product according to any one of claims 1 to 3, wherein the resin temperature is 250 to 360 ° C and the mold temperature is 60 to 170 ° C. 5. The method for producing a foamed molded product according to claim 1, wherein a molding machine having a shutoff nozzle is used.