JPS6345967B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is provided with a glass holding groove, and has car body lip parts formed on both sides of the upper side of a main body part attached to a window frame flange, and at least the car body lip part on the outside of the car body is tapered. This invention relates to automobile window frame rubber made of thermoplastic rubber.

From the standpoint of reducing the fuel consumption of modern automobiles, there is a growing demand for window frame rubber to be lighter, and one possible means to achieve this is to use low specific gravity materials. Naturally, this low specific gravity material has the physical properties required for general window rubber, that is, 50 to 75Hs (JIS-A hardness).
It is desirable that the material be a thermoplastic material that has softness and good compression set properties, weather resistance, heat resistance, etc., and that does not require a vulcanization process from the viewpoint of moldability (productivity).

Polyolefin thermoplastic rubber (hereinafter referred to as "TPO") is a material that satisfies the above conditions.
That is, the specific gravity of TPO is generally 0.88 to 0.91, which is smaller than that of conventional window frame rubber materials, 0.95 to 1.35 for vulcanized ethylene propylene terpolymer (EPT) and 1.16 to 1.45 for flexible polyvinyl chloride (PVC). It also has excellent compression set properties, weather resistance, heat resistance, etc. However, this TPO does not have good kerosene resistance,
It is considered unsuitable as a material for window frame rubber, as the outer lip of the vehicle is exposed to kerosene cleaning during the wax removal process after installation on an actual vehicle. In other words, the wax removal process refers to cleaning with a kerosene dispersion liquid that removes the wax applied to the car body from corrosive factors such as salt air and moisture during inventory and transportation immediately before sale. As a result, the lip of the car body on the outside of the car swells, and the dimensional difference between it and other parts that are less swollen increases, causing a waving phenomenon in the lip, which impairs the appearance of the car.

In view of the above, this invention has developed a TPO that allows the outer lip of the vehicle to withstand kerosene cleaning.
The purpose of the present invention is to provide an automobile window frame rubber consisting of:

The automobile window frame rubber of the present invention achieves the above object by having a wall thickness of 0.8 mm or more at least at a portion 2 mm away from the tip of the vehicle body lip on the outside of the vehicle.

Hereinafter, embodiments of the present invention will be described based on illustrated examples.

Here, as shown in FIG.
The explanation will be given by taking as an example a window frame rubber 6 in which tapered vehicle body lip parts 4 and 5 are formed on both sides of the upper side, but the window frame rubber is not limited to this type.

The window frame rubber 6 is made of TPO and has a wall thickness of 0.8 mm or more at least at a portion 2 mm away from the tip of the vehicle body lip 5 on the outside of the vehicle.

The above-mentioned TPO has a hardness of 50 to 75 Hs (JIS-A) required for conventional window frame rubber, and has a specific gravity of 0.9 or less from the viewpoint of weight reduction. At this time,
It is preferable that TPO be partially cross-linked to the extent that thermoplasticity is not impaired, since various physical properties such as heat aging resistance and compression set are improved over those that are not cross-linked at all. For example, in the case of polypropylene (PP)-ethylene propylene terpolymer (EPT) TPO, organic peroxide, divinylbenzene, etc. are blended as a crosslinking agent. Specific examples of TPO include Thermolan 398B (trade name; manufactured by Japan Synthetic Rubber Co., Ltd.), Milastomer 5520B (manufactured by Mitsui Petrochemical Industries, Ltd.), and Sumitomo TPE8721 (trade name; manufactured by Sumitomo Chemical Industries, Ltd.). can be mentioned.

The reason for limiting the dimensions of the vehicle body lip portion 5 as described above is supported by the following kerosene resistance test results.

Materials used: Thermolan 398B Kerosene liquid used: Kerosene 10 vol% dispersion (dispersion medium: water, liquid temperature: 80°C); This is the same as a normal kerosene cleaning liquid.

<Test A> Measure the thickness of a 100 x 10 mm strip made of the above material.
Each test piece, whose length was varied from 0.1 to 2 mm at 0.1 mm intervals, was immersed in the above kerosene solution for 3 minutes, the length before and after immersion was measured, and the calculated rate of change in length was plotted. The results are shown in Figure 2. . The basis for this 3 minute immersion is:
This is because kerosene washing in the wax removal process usually takes 1 to 2 minutes. From the results shown in Figure 2, it was found that when the thickness is less than 0.8 mm, the thinner the thickness, the greater the rate of change in length, but when the thickness is 0.8 mm or more, the rate of change in length hardly changes. this is,
Even if exposed to kerosene cleaning solution for a very short time,
It is thought that as long as a TPO molded product has a certain thickness, kerosene will not penetrate sufficiently into the inside and will not swell.

<Test B> Based on the results of the above Test A, window frame rubbers with the thickness of the tip of the lip part of 0.6, 0.8, 0.9, and 1.0 mm were made using the above materials, and were washed with the above kerosene cleaning solution for 3 minutes. When washed, the 0.6 and 0.7 mm ones caused waving, but 0.8 mm or more did not cause waving.

<Test C> As shown in Figure 3, additional l (mm) = 0.5, 1.0, 1.0, 1.5, 2.0, 2.5 mm is added to the tip with a thickness of 0.8 mm.
The lip portion 5 is an extension of a tapered wedge-shaped cross section.
Using the above materials, we prototyped a window frame rubber with
When kerosene was washed in the same manner as Test B,
Waviness did not occur between 0.5 and 2.0 mm, but 2.5 mm
The tip was slightly wavy only at the tip.

Since the automobile window frame rubber of this invention has the above-mentioned structure, it is made of TPO, but the lip part of the car body on the outside of the car can withstand kerosene cleaning, and the lip part does not wave after kerosene cleaning. . Therefore, TPO can be used as a material for window frame rubber, and the weight of window frame rubber can be easily reduced.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of window frame rubber, Figure 2 is a graph showing the relationship between the thickness of a TPO molded product and kerosene resistance, and Figure 3 is a graph showing the relationship between the thickness of a TPO molded product and kerosene resistance. FIG. 6 is a diagram showing the shape of a lip when testing the relationship between distance and kerosene resistance. 5...Vehicle body lip on the outside of the vehicle, 6...Window frame rubber.

Claims (1)

[Scope of Claims] 1. Vehicle body lip portions are formed on both sides of the upper side of the main body which is provided with a glass gripping groove and is attached to a window frame flange, and at least the vehicle body lip portion on the outside of the vehicle is tapered and made of polyolefin thermoplastic rubber. For window frame rubber that is made of
An automobile window frame rubber characterized by having a wall thickness of 0.8 mm or more at parts separated by mm.