JPS59166543A - Resin composition for polypropylene hinge - Google Patents

Abstract

PURPOSE:The titled composition that is composed of at least one selected from polypropylene homopolymer and propylene-ethylene copolymers which contain a specific amount of ethylene and have a specific MFR (melt flow rate), thus being suitable for use in accelerator pedals for cars, because of its high tear strength, adhesion and flexibility. CONSTITUTION:The objective composition is composed of at least one selected resin from polypropylene homopolymer, ethylene-propylene copolymer mainly containing propylene, low-density polyethylene, ethylene-propylene rubber and ethylene-propylene-diene terpolymer, and contains 5-50wt% of ethylene component with an MFR of 0.5-10g/min in composition. USE:A variety of vessel in which the cover is formed integrally with the major body.

Description

DETAILED DESCRIPTION OF THE INVENTION In particular, the present invention relates to a polypropylene hinge composition in which a bending member and a support member are joined and integrally molded.

Polypropylene has excellent bending fatigue resistance,
This characteristic is applied to molded products 2 in which a thin wall portion is provided in a molded product and used at a bent portion 1, for example, in various containers in which a container and a main body are integrally molded, or in automobile accelerator pedals. In these molded products having a so-called integral hinge structure, both the bending member and the non-bending member (hereinafter referred to as the support body) are made of the same resin.

During molding, the resin passes through a narrow gap in the mold corresponding to the bent portion and is filled from a cavity corresponding to one support into a cavity corresponding to the other support. Therefore, from the viewpoint of ease of molding, a resin with high fluidity is preferable, but on the other hand, in order to increase the strength of the molded product and the strength of the bent part, a resin with low fluidity must be used. This was a major hindrance to product manufacturing.

As a result of our dedicated efforts to solve the above-mentioned problems of the conventional integral hinge structure, the present inventors have succeeded in improving strength and strength by joining a pre-formed bending member to a supporting member when molding a polypropylene hinge. I learned that polypropylene hinges with excellent moldability could be obtained, and applied for a utility model registration for polypropylene hinges.
0'i'22).

The support member constitutes the main body of the molded product, which has a hinge structure, and polypropylene with characteristics that match the physical properties required for this molded product can be freely selected and used, and fillers, colorants, etc. can also be added. I can do it.

The bending member obtained by molding in advance is attached to a predetermined position in a mold for forming the support member, the molten resin that is to form the support member is press-fitted, and the bending member and the support member are integrally molded by welding. A so-called insert molding method can be preferably used, but such a bending member requires high tear strength, appropriate flexibility, and strong adhesive strength with the supporting member. Propylene homopolymer has high rigidity, and when used as a bending member, the bending resistance of the hinge portion is large.

It is particularly unsuitable for use in low-temperature conditions, and furthermore, because the melting point is high, in order to obtain good adhesive strength with the support member, the mold temperature during insert molding and the molten water content of the support member resin must be high. However, it required a long cooling time, and the material was not necessarily satisfactory.

The present inventor investigated a resin for bending members of polypropylene hinges and found a propylene homopolymer.

Copolymer of propylene and ethylene whose main component is propylene, low density polyethylene (1・DPE), ethylene・
A composition consisting of one or more resins selected from propylene rubber (Ti'PR) and ethylene propylene HW turbopolymer (EPDM), wherein the ethylene component in the mixture is 5~5Q
wt, and its MFR is 0.5~10~(,
9/min) has excellent properties as a bending member, and has completed the present invention.

As the polypropylene which is the main component of the composition of the present invention, in addition to propylene homopolymers, random copolymers or block copolymers of propylene and ethynine, which have propylene as the main component, can be used. Low-density polyester can be added to the above-mentioned polypropylene for the purpose of improving its flexibility and adhesion during molding. The density is 0.913-0.94 for low-density polyethylene! 5 f, /
Melt index in Han 3 (MI, JISK, 7210
According to Case 4) 0.1~8ゐ/10m1n, and MF as F3PR or EPDM.
Any one in which R is 0.2 to 10 y/10 m1n, y component is 20 to 8 Q, wt cl, is preferably used.

Each raw material resin has an ethylene component in the composition (the sum of the loss between the ethylene component in the valley raw resin and the concentration of its resin l'IN in the composition) of 5 to 5 QWtφ, and a melt flow rate (MFR) of the composition. , J engineering 5K7210 case 14) is 0
．． It must be mixed within a range of 5 to 10 #/10 m1n. Ethylene component is less than 5wt95 or M
When F R is less than 0.511/10 m1n, the resulting bending member lacks flexibility and has poor adhesion to the supporting member. Also, if the ethylene content exceeds 5Qwt, the MFR will be 1.
0? If it exceeds /10m1n, the strength of the bending member decreases, making it practical and young.

The present invention will be explained in more detail with reference to Examples.

Each 4a product is made by mixing pellet-shaped raw resins in a predetermined weight ratio in a tumbler mixer, and then molding them into a sheet with a thickness of Q and 4 mm using an extruder equipped with a T-die. was evaluated. The raw material resins and performance evaluation methods used for each are listed below.

The evaluation results are shown in the table ■Raw material resin a Polypropylene (homopolymer) MFR? 5.0
b Polypropylene (random copolymer) MP'R:
'i', 0 ethylene: ;, QWt俤C;f? +) 7' Robylene (random copolymer) MF
R: 5.0 Ethylene: (5wt polypropylene (block copolymer) MFR: 2
, 5 ethylene: 11. OWt e polypropylene (block copolymer) MFR: 2
．． 0 ethylene: 18. Owt ratio f Low density polyethylene MI: 1.5 Density 0.9
10 V□3gKPRMFR=4.4 Tongue cut 50
wt%h KPDM MFR: 0,5
Ethi L/, / 5,5 wt%i KPDM
MFR: Q, 4x, 19y 75
wt [■ Melt flow rate (MFR) = J]: 5K
m tear strength according to Article 7210 Article 6-Case 14: According to J Engineering 5F8116, T of the sample sheet
The tear strength in the D force direction was determined.

■ Adhesiveness: The hinge shown in Figure 1 was made using the insert molding method, two 1U11 supporting members were twisted in opposite directions, and the damage state of the bent members was observed. Items due to peeling are not allowed, items where peeling and breakage coexist are allowed.

Those with only breakage were judged to be good.

V flexibility: Using the same hinge as used for adhesive evaluation 1, 5 was tested under two conditions: room temperature (23℃) and low temperature (-30℃)
A bending test was conducted using a weight of 0 t. If the angle of force of the upper part against the lower part held vertically is 120° or more, X, and if it is less than 120° and 900 or more, △
, 90 tastes were judged as 60° or more, 0, and less than 60° as ◎.

=371

[Brief explanation of the drawing]

Figure 1: Perspective view of test polypropylene hinge Figure 2:
Schematic diagram of flexibility test A: hinge length 150 mm). B: Width of the bending member ('15 mm). C: Width of hinge (53mm). D: Thickness of bending member, 0.4JII1m). E: Bend angle of hinge or more 9- O L mouth

Claims (1)

[Claims] (1) Polyglopylene homopolymer, a copolymer of propylene and ethylene whose main component is propylene. A composition consisting of low density polyethylene (LDPlB), one or two or more types of ethylene resin, the ethylene component in the composition is 5 to 50 Wt, and the MIFR is 0. .5~10 (f/m1n)
A resin composition for polypropylene hinges.