Ethylene vinyl acetate (EVA) vehicle water retaining film

Abstract

The utility model discloses an EVA water retaining film for an automobile, and relates to the technical field of automobile body components of automobiles, the EVA water retaining film for the automobile comprises an EVA film and a PE / PA film, the PE / PA film is an asymmetric film, one surface of the PE / PA film is a PE surface, and the other surface of the PE / PA film is a PA surface; the PE surface of the PE / PA film is thermally compounded with the EVA film; the PE / PA film is compounded on the surface of the EVA water retaining film, so that the tearing strength can be obviously improved to 15-28MPa, and tearing caused by pulling the wire harness is avoided.

Description

Technical Field

[0001] The present application relates to a vehicle body component, and in particular to an EVA vehicle water-retaining film with a layered structure. Background Art

[0002] The existing EVA car waterproof film is made by first producing EVA coils (or sheets), then forming them through hot felt cold mold, vacuum forming or compression molding, and finally back-coating with hot melt adhesive.

[0003] For automotive water-retaining films, researchers focus more on improving the sound insulation, noise reduction, or heat insulation effects of the water-retaining films, but rarely on the tear strength of the water-retaining films. For example, a Chinese patent with announcement number CN203111073U discloses an automotive heat insulation and noise reduction water-retaining film, including a water-retaining film, a heat insulation layer is provided on one side of the water-retaining film, and a sound insulation layer is provided between the water-retaining film and the heat insulation layer, so as to achieve the effects of heat insulation, noise reduction and water-retaining. For example, a Chinese patent with announcement number CN202163052U achieves the effects of sound absorption, heat insulation and water-retaining by adding a sound-absorbing layer and a heat insulation layer.

[0004] The tear strength of existing automotive waterproof films is usually 5-8MPa. The applicant found that in winter, the EVA waterproof film of a certain brand of North American new energy vehicles is easily torn and fails after it hardens. However, if we want to significantly improve the tear strength of the EVA waterproof film, it is difficult to achieve success by simply adjusting the formula. Utility Model Content

[0005] In view of this, the present application provides an EVA automotive water-retaining film, which can significantly improve the tear strength by compounding a layer of PE / PA film on the surface of the EVA water-retaining film; the specific technical solutions adopted are as follows:

[0006] The EVA car water-retaining film comprises an EVA film and a PE / PA film, wherein the PE / PA film is an asymmetric film, one side of the PE / PA film is a PE side, and the other side is a PA side; the PE side of the PE / PA film is thermally compounded with the EVA film.

[0007] Preferably, the PE / PA film is a symmetrical film, both sides of the PE / PA film are PE sides, and any PE side of the PE / PA film is thermally composited with the EVA film;

[0008] Further preferably, both PE surfaces of the PE / PA film are thermally compounded with EVA films.

[0009] Preferably, the content of PA in the PE / PA asymmetric membrane is 18-35 wt%.

[0010] Preferably, the PE / PA asymmetric film is a seven-layer co-extruded film or a nine-layer co-extruded film.

[0011] Advantages of this application: By laminating a layer of PE / PA film on the surface of the EVA water blocking film, the tear strength can be significantly increased to 15 - 23 MPa; meanwhile, it can solve the problem that the material (especially EVA material) becomes hard in low-temperature environments, resulting in poor material followability and the water blocking film coming unstuck. Description of the Drawings

[0012] Figure 1 It is a schematic diagram of the first structure of the EVA water blocking film for vehicles in this application;

[0013] Figure 2 It is a schematic diagram of the second structure of the EVA water blocking film for vehicles in this application;

[0014] Figure 3 It is a schematic diagram of the third structure of the EVA water blocking film for vehicles in this application.

[0015] In the figure: 1: EVA film, 2a: PE / PA asymmetric film, 2b: PE / PA asymmetric film, 3a, 3b, 3b': PE surface, 4: PA surface. Detailed Embodiments

[0016] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the drawings of this application. Obviously, the described embodiments of this application are only partial embodiments of this application, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0017] EVA, ethylene-vinyl acetate copolymer (also known as ethylene-ethyl acetate copolymer) is prepared by copolymerizing ethylene (E) and vinyl acetate (VA).

[0018] PE is polyethylene material, PA is polyamide material, commonly known as nylon; the PE / PA asymmetric film or symmetric film involved in this application are all commercially available multi-layer co-extruded films, such as commercially available seven-layer co-extruded films or nine-layer co-extruded films; the PA content is 18 - 35 wt%, and the film thickness is 35 μm - 180 μm, all of which are commercially available specifications. This application does not involve improvements to the PE / PA film material itself.

[0019] Followability can be understood as: the performance of the material to conform to the mold cavity. Generally, when the material is soft, the followability is better; when the material is hard, the followability becomes worse.

[0020] The tear strength is tested in accordance with GB / T 10808 - 2006, and the tensile strength is tested in accordance with GB / T 10654 - 2001.

[0021] Example 1

[0022] Combination Figure 1 The EVA automotive water-retaining film comprises an EVA film 1 and a PE / PA asymmetric film 2a. The PE / PA film is an asymmetric film, one side of the PE / PA film is a PE surface 3a, and the other side is a PA surface 4; the PE surface 3a of the PE / PA film is thermally composited with the EVA film 1.

[0023] The content of PA in the PE / PA asymmetric film is 18-35wt%, the thickness of the PE / PA film is 35μm-180μm, and the preferred thickness of the PE / PA film is 85μm-105μm. If the PE / PA film is too thick, it will cause the film to warp unevenly, and if it is too thin, the tear strength will hardly reach above 20MPa.

[0024] For PE / PA films of the same thickness, the tensile tear properties will improve with the increase of PA content, but the PA content is generally between 18-35. If it is higher, the PE / PA film forming effect may be poor due to the large difference in molding temperature and shrinkage between PE and PA. Therefore, the PA content is generally between 18-35, which is the commercially available specification.

[0025] PE / PA asymmetric membranes with a PA content of 25wt% and thicknesses of 85μm, 105μm and 125μm were purchased and thermally compounded with EVA water-retaining film substrates to obtain improved EVA automotive water-retaining films. The improved EVA automotive water-retaining film and the EVA automotive water-retaining film before improvement (corresponding to 0μm in Table 1) were tested for tear strength and tensile strength, respectively. The test results are shown in Table 1. The test results show that the improved EVA automotive water-retaining film has excellent tear strength and tensile strength, which are sufficient to avoid tearing caused by pulling the wiring harness, and can solve the problem of debonding of the water-retaining film due to hardening of the material and poor follow-up performance under low temperature conditions.

[0026] Table 1 Test results

[0027]

[0028] Example 2

[0029] like Figure 2 On the basis of Example 1, the PE / PA film is a PE / PA symmetric film 2b, the two sides of the PE / PA film are PE side 3b and PE side 3b', and any PE side of the PE / PA film is thermally composited with the EVA film 1.

[0030] Example 3

[0031] Based on Example 1, the PE / PA membrane is a PE / PA symmetric membrane 2b. The two sides of the PE / PA membrane are a PE side 3b and a PE side 3b' respectively. EVA membranes 1 are thermally laminated on both PE sides of the PE / PA membrane.

Claims

1. EVA automotive water-retaining film, including EVA film, characterized in that: It also includes a PE / PA film, wherein the PE / PA film is an asymmetric film, one side of the PE / PA film is a PE side, and the other side is a PA side; the PE side of the PE / PA film is thermally composited with the EVA film.

2. The EVA vehicle water-retaining film according to claim 1, characterized in that: The content of PA in the PE / PA film is 18-35wt%.

3. The EVA vehicle water-retaining film according to claim 1, characterized in that: The PE / PA film is a seven-layer co-extruded film or a nine-layer co-extruded film.

4. The EVA vehicle water-retaining film according to claim 1, characterized in that: The PE / PA film has a thickness of 85 μm-105 μm.

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