JPH10202795A - Polyoxymethylene molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance grease-resistance and environmental stress cracking resistance by forming a polyoxymethylene/fluorine based polymer alloy layer partly or wholly on the surface layer of a polyoxymethylene molded body. SOLUTION: In this polyoxymethylene molded body, a POM/fluorine based polymer alloy film is laminated partly or wholly on the surface layer of a polyoxymethylene (POM) molding. A PTFE is used as the fluorine based polymer and the POM/fluorine based polymer alloy film is laminated on a surface layer 0.1-1.0mm. A decorating molding or a press molding is used as a molding method. That is, after the POM/PTFE alloy film 3 is set up into position in an upper mold 1 and a lower mold 2, a melt POM 4 is injected in the upper mold 1 and a lower mold 2, or the interior of the mold is held at a high temperature to melt and set the POM 4 pellet to integrate the said alloy film 3 and the base material POM 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyoxymethylene (POM) molded article used for home appliances, vehicles, and the like, and particularly to a POM molded article having POM / PTFE as a laminated material on its surface layer and having excellent environmental resistance. About the body.

[0002]

2. Description of the Related Art Polyoxymethylene (POM) is mainly used for transmitting drive output as a movable part for automobiles, home electric appliances and the like, and is intended to reduce noise and weight as an alternative to metal gears. There is a demand for higher functionality in each field. For this reason, commercially available POM materials are imparted with high mechanical properties and deterioration resistance by kneading and molding fibers, inorganic powders, fillers, common additives, and the like into a resin composed of a homopolymer or a copolymer. An example of the POM material is disclosed in JP-A-8-109308. However, the use of POM in mechanical parts such as sliding parts and gears has recently increased in the automotive field and the like. Therefore, it is necessary to improve the environmental degradation resistance of POM molded articles in the presence of an environmental agent containing grease. ing.

[0003]

Problems to be Solved by the Invention Additives and fiber materials are kneaded in POM materials used for mechanical parts in order to maintain creep resistance and high mechanical properties. Further, grease is applied to improve wear characteristics. However, since swelling of the grease with respect to the POM molded body under high temperature and high sliding for a long period of time is unavoidable, there is a possibility that the environmental stress cracking property of the POM molded body is promoted. Therefore, in order to improve the environmental stress cracking property, it is necessary to further improve the grease resistance of the POM molded article.

[0004]

Means for Solving the Problems The present invention has been made in view of such a conventional problem, and in order to improve grease resistance, a part or the whole of a surface layer of a polyoxymethylene (POM) molded body. A POM molded article having a POM / fluorine-based polymer alloy layer formed on the POM.

That is, in the polyoxymethylene molded article according to the first aspect, a POM / fluorine-based polymer alloy film is laminated on part or all of the surface layer of the polyoxymethylene (POM) molded article. In the polyoxymethylene molded article according to claim 2, in the polyoxymethylene molded article according to claim 1, P is used as the fluoropolymer.
It was configured to use TFE. According to a third aspect of the present invention, there is provided the polyoxymethylene molded article according to the first aspect, wherein a polyoxymethylene / fluorine-based polymer alloy film is laminated on a surface layer of 0.1 to 1.0 mm. In the polyoxymethylene molded article according to the fourth aspect, in the polyoxymethylene molded article according to the first aspect, the polyoxymethylene / fluoropolymer alloy film is made of PTFE1 to PTFE4 based on 100 parts by weight of POM.
It was configured to be 0 parts by weight. In the polyoxymethylene molded article according to the fifth aspect, in the polyoxymethylene molded article according to the first aspect, a polyoxymethylene / fluorine-based polymer alloy film is subjected to decorative molding or press molding on a part or the entire surface of the molded body. The configuration was adopted.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Polyoxymethylene (POM) used in the present invention is a homopolymer or a copolymer. The POM / fluorine-based polymer alloy film is composed of two kinds of POM or a blend of the two, and the fluorine-based polymer is PTFE,
PHFP, PVDF or fluoro rubber. The polymer alloy component is not particularly limited. Hereinafter, POM homopolymer (referred to as POM), POM
A POM molded article using an M / PTFE alloy film will be described. Specifically, POM / P is a POM / PTFE film obtained by alloying 1 to 40 parts by weight of PTFE with respect to 100 parts by weight of POM of POM / PTFE.
A TFE film of 0.1 to 1.0 mm is used. POM /
Extrusion molding or blow molding using a film die can be used as a method for molding the PTFE film.

As a molding method, decorative molding or press molding is used. That is, after the POM / PTFE alloy film 3 is arranged at an appropriate position in the upper mold 1 and the lower mold 2 shown in FIG. Holds the inside of the mold at a high temperature, melts and solidifies the POM4 pellets, and integrates the alloy film 3 and the base material P0M4. At this time, since the base material P0M4 and the alloy component described above are common, the adhesion between the two is good.

[0008] The POM molded body 5 thus obtained
Shows very good environmental stress cracking resistance. Incidentally, the embedding of environmental stress cracking resistance is improved by the solubility parameter (SP) of the polymer alloy layer on the surface of the molded product.
Value) is significantly different from the SP value of the environmental agent (grease, water, etc.), so that the POM does not easily swell with the environmental agent. and,
It is conceivable that the polymer alloy layer well follows the deformation of the POM molded body 5 when a load is applied, and this alloy layer is not broken, so that the above-mentioned environmental resistance property can be maintained for a long time.

[0009]

Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing an embodiment of the present invention and an example to be compared with the embodiment. Explaining the configuration of this figure, the polyoxymethylene (hereinafter referred to as P0M) /
It shows the type, content, film thickness, resin temperature during molding, mechanical properties, and time until environmental stress cracking in a POM creep durability test of a fluoropolymer alloy film. Alloy film molding method is POM
/ A fluorine-based polymer alloy resin was produced under the following conditions by an extrusion molding method using a film die corresponding to each film thickness and formed into a film. Resin temperature: 170 to 200 ° C. In the molding method, both decorative molding and press molding were performed under the following conditions, and a POM / PTFE alloy film was laminated on the entire surface (JIS No. 1) to obtain a creep test piece. Mold temperature: 80 ° C. Resin temperature: 180 to 220 ° C. A creep durability test with grease applied was performed under the following conditions, and the time when cracks occurred on the surface of the test piece was measured. Temperature: 100 ° C. Load: 200 kgf / cm ² Application grease: Multemp SA, Nippeco LT1K, Foil AH137

Hereinafter, embodiments of the present invention will be described. 1. When the polymer alloy component PTFE is less than 1 part by weight, the environmental stress cracking resistance is not improved as shown in Comparative Example 1. If PTFE is more than 40 parts by weight, a homogeneous film cannot be obtained because POM / PTFE is not compatible with each other, and adhesion to the base material POM is also insufficient. (Comparative Example 2) 2. Alloy film thickness If the film thickness is less than 0.1 mm, as shown in Comparative Example 3, if the film thickness is less than 0.1 mm, it cannot be used because it melts during molding and mixes with the base material POM.

When the film thickness is greater than 1.0 mm, the mechanical properties of the alloy are lower than that of the POM, so that the mechanical properties of the molded body are reduced. (Comparative Example 4) 3. When the resin temperature is <180 ° C., the welding between the POM substrate and the alloy film is insufficient. (Comparative Example 5) When the resin temperature is greater than 220 ° C, the POM substrate and the alloy film cannot be used because they are melted and mixed. (Comparative Example 6) The other molding conditions (injection speed, mold pressure, cooling time, etc.) are not particularly limited, since the conventional molding conditions for POM are applied.

<Embodiments 1, 2, 3> In Embodiment 1, the PT
The concentration of the FE polymer alloy film was set to 1.0 part by weight of PTFE based on 100 parts by weight of POM.
A molded article obtained by decorative molding and press molding was prepared by setting the concentration of the E polymer alloy film to 20 parts by weight of PTFE with respect to 100 parts by weight of POM, and in Example 3, setting the concentration of the PTFE polymer alloy film to 40 parts by weight of PTFE with respect to 100 parts by weight of POM. The results of creep evaluation as cut out as a piece were shown.

<Embodiments 4 and 5> In Embodiment 4, Embodiment 2
PTFE polymer alloy film thickness of 0.1 mm,
In Example 5, a molded article obtained by decorating and press-molding the PTFE polymer alloy film of Example 2 with a thickness of 1.0 mm was cut into JIS No. 1 pieces, and grease was applied to the test pieces to evaluate creep. The results are shown below.

Embodiments 6 and 7 In Embodiment 6, Embodiment 2
The resin temperature at the time of molding was 180 ° C. using the PTFE polymer alloy film of Example 7, and the resin temperature at the time of molding was 22 in Example 7 using the PTFE polymer alloy film of Example 2.
The molded body obtained by the decorative molding and the press molding at 0 ° C. was cut out into JIS No. 1 pieces, and grease was applied to the test pieces to evaluate the creep.

<Conventional Example> This is a molded article in which a PTFE polymer alloy film is not laminated, and is the same as in Example 1.

<Comparative Examples 1 and 2> In Comparative Example 1, Example 1
PTFE polymer alloy film concentration of POM100
0.8 parts by weight of PTFE based on the weight, and in Comparative Example 2, the concentration of the PTFE polymer alloy film of Example 1 was P0M
The results obtained by cutting out a molded article obtained by decorative molding and press molding with 45 parts by weight of PTFE with respect to 100 parts by weight as JIS No. 1 piece and evaluating creep were shown.

<Comparative Examples 3 and 4> In Comparative Example 3, Example 2
PTFE polymer alloy film thickness 0.08m
m, Comparative Example 4 shows the results of creep evaluation of a PTFE polymer alloy film of Example 2 having a thickness of 1.2 mm, obtained by cutting out a molded body obtained by decorative molding and press molding into JIS No. 1 pieces.

<Comparative Examples 5 and 6> In Comparative Example 5, Example 2
The resin temperature at the time of molding was 170 ° C., and Comparative Example 6 was Example 2
The molded body obtained by decorative molding and press molding at a resin temperature of 230 ° C. during molding was cut into JIS No. 1 pieces, and the results of creep evaluation were shown.

<Comparative Examples 7, 8, 9> In Comparative Example 7, the fluoropolymer of Example 2 was PHFP, Comparative Example 8 was PVDF, and the fluoropolymer of Example 2 was Comparative Example 9. The molded article obtained by decorative molding and press molding using the fluorine-based polymer as the fluorine rubber was cut into JIS No. 1 pieces, and the results of creep evaluation were shown.

[0020]

As described above, according to the present invention, when the PTFE concentration of the PTFE polymer alloy film is set to 1 to 40 parts by weight, the laminated thickness of the molded product obtained by the decorative molding and the press molding is set to 0.1. By setting the thickness to 1 to 1.0 mm, durability against environmental stress cracking is improved,
The effect of extending the life of the POM component can be obtained.
Further, the lamination thicknesses shown in Examples 4 and 5 have the effect of improving the durability against environmental stress cracking, and the decorative properties and press molding can be partially performed. There is no.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a method for molding a POM molded article of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention and an example to be compared with the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper mold 2 Lower mold 3 Alloy film 4 POM 5 POM molded object

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 627: 12 671: 00 B29L 9:00

Claims (5)

[Claims] 1. A polyoxymethylene molded article characterized in that a polyoxymethylene / fluorine-based polymer alloy film is laminated on part or all of the surface layer of the polyoxymethylene molded article. 2. The polyoxymethylene molded article according to claim 1, wherein PTFE is used as the fluorine-based polymer. 3. The polyoxymethylene molded article according to claim 1, wherein a polyoxymethylene / fluoropolymer alloy film is laminated on a surface layer of 0.1 to 1.0 mm. 4. The polyoxymethylene molded article according to claim 1, wherein the polyoxymethylene (POM) / fluoropolymer alloy film is used in an amount of 1 to 40 parts by weight of PTFE based on 100 parts by weight of POM. 5. The polyoxymethylene molded article according to claim 1, wherein the polyoxymethylene / fluorinated polymer alloy film is obtained by decorating or press-molding a part or the whole of the molded article.