Multi-layer flexible composite inner sealing strip and application method thereof

Abstract

The invention provides an inner sealing strip capable of being used for a multilayer flexible composite material and an application method thereof, the inner sealing strip is composed of a protective layer, a gas barrier layer, an interface layer and a sealing layer in sequence from outside to inside, and the protective layer, the gas barrier layer, the interface layer and the sealing layer are connected with one another. The problems of fatigue damage, sealing strip damage, poor air tightness of an air bag welding seam and the like after long-time action and repeated bending and bending action in a high-temperature environment are solved.

Description

Technical Field

[0001] The invention relates to the field of composite materials, and in particular to a multi-layer flexible composite inner sealing strip and an application method thereof. Background Art

[0002] Multilayer flexible composite materials are an important component of the airship bladder. The performance and quality of multilayer flexible composite materials directly affect the service quality of the airship bladder. For the airship bladder, the weld sealing and sealing strength of the multilayer flexible composite material are important properties. At present, in the preparation process of airship airbags, in order to ensure the airtightness of the entire airbag and provide good weld protection, an outer sealing strip and the outer surface of the multilayer flexible composite material are generally used for hot pressing to achieve sealing and protection of the weld area. However, due to the limitations of the outer surface of the flexible composite material and the material and structure of the outer sealing strip, the inner sealing strip is prone to interface debonding and fatigue damage after being subjected to high temperature environment for a long time and repeated bending and flexing, which will cause the airbag to become less sealed and further affect the long-term stable operation of the airbag. Summary of the invention

[0003] The present invention provides an inner sealing strip which can be used for a multi-layer flexible composite material and a method for using the same, which solves the problems of fatigue damage or body damage of the inner sealing strip or the sealing part, poor airtightness of the airbag weld, etc. after long-term exposure to high temperature environment and repeated bending and flexing.

[0004] In order to solve the above technical problems, the present invention provides a multi-layer flexible composite inner sealing strip, which is composed of a protective layer, a gas barrier layer, an interface layer and a sealing layer from the outside to the inside, and the protective layer, gas barrier layer, interface layer and sealing layer are connected to each other.

[0005] The protective layer is mainly realized by coating a layer of polyurethane or fluoride material on the gas barrier layer. In order to ensure that the inner sealing strip has fatigue resistance such as rubbing resistance and bending resistance while meeting the ultraviolet protection performance, polyurethane material is preferably used as the protective layer, and the thickness of the protective layer ranges from 0.5μm to 2.0μm.

[0006] Preferably, the polyurethane can be selected from any one of aromatic polyurethane, aliphatic polyurethane or a mixture of the above two polyurethane materials. In order to form a strong interface fastness, aromatic polyurethane is preferred.

[0007] Preferably, the protective layer is prepared from the following raw materials in parts by weight: 60 to 70 parts of polyurethane, 5 to 15 parts of titanium dioxide, 5 to 10 parts of silicon dioxide and 5 to 25 parts of isocyanate.

[0008] Preferably, the isocyanate is any one of triphenylmethane triisocyanate, tri(4-phenylisocyanate)phosphorothioate or dimethyltriphenylmethane tetraisocyanate. In order to form higher interlayer fastness, tri(4-phenylisocyanate)phosphorothioate is preferred.

[0009] Preferably, the gas barrier layer is a barrier modified polyurethane film, which may be a three-layer structure or a two-layer structure, and the thickness of the gas barrier layer ranges from 5 μm to 12 μm.

[0010] Preferably, the barrier modified polyurethane film may be a three-layer structure, which includes polyurethane TPU, ethylene-vinyl alcohol copolymer EVOH, and polyurethane TPU in sequence, and the thickness ratio of the three-layer film is 1:2:1.

[0011] Preferably, the barrier modified polyurethane film may be a two-layer structure, which is polyurethane TPU and EVOH in sequence, and the thickness ratio of the two layers of film is 1:2.

[0012] Preferably, the interface layer can be any one of a two-component polyurethane adhesive, a one-component polyurethane adhesive or a polyisocyanate adhesive, and the thickness of the interface layer is 0.5 μm to 1.5 μm.

[0013] Preferably, for the convenience of construction and the formation of higher interlayer fastness, a polyisocyanate adhesive is preferred, specifically any one of JQ-1 adhesive, JQ-4 adhesive, Desmodur RF, Desmodur RFE, Desmodur R or Desmodur RE, and a mixture of any two of the above polyisocyanate adhesives can also be used as the interface layer, with a mixing ratio of 1:1 to 1:2;

[0014] Preferably, the sealing layer consists of a first sealing layer and a second sealing layer; the first sealing layer is connected to the interface layer, the second sealing layer is connected to the material to be sealed, and the thickness of the sealing layer is 20 μm to 50 μm.

[0015] Preferably, the first sealing layer is prepared from the following raw materials in parts by weight: 70-85 parts of polyurethane hot melt adhesive; 5-10 parts of white carbon black; 5-25 parts of carbon black; in order to achieve a better sealing effect, the polyurethane hot melt adhesive is an aliphatic polyether polyurethane structure, and the diisocyanate part is preferably IPDI; the melting point of the polyurethane hot melt adhesive needs to be controlled at 70°C to 130°C;

[0016] Preferably, the second sealing layer is prepared from the following raw materials in parts by weight: 100 parts of water-based polyurethane adhesive and 3-10 parts of curing agent; the second sealing layer is formed by brushing on the surface of the material to be sealed; the second sealing layer is a polyurethane adhesive layer with a curing agent reaction system, which can effectively improve the fastness and air tightness of the sealing layer.

[0017] Based on the same inventive concept, the present invention also provides an application method for a multi-layer flexible composite inner sealing strip, comprising the following steps:

[0018] S1: Preparation of adhesive for the second sealing layer of the inner sealing strip: prepare the water-based polyurethane adhesive and the curing agent according to a predetermined mass ratio, and mix them evenly with a stirrer for 15 to 30 minutes. When there is no sediment in the mixture, it can be judged that the mixture is evenly mixed;

[0019] S2: Apply the second sealing layer: Apply the prepared water-based polyurethane adhesive to the area to be sealed with a nylon brush or a nylon bristle brush for at least 2 times. Dip the brush into the mixed adhesive and apply it to the area to be sealed. During the application process, apply the adhesive back and forth in a straight line until it is evenly applied. If shrinkage holes or bubbles appear on the surface during the application process, leave it in the air for about 2 minutes and then apply it with a brush until the shrinkage holes or bubbles disappear.

[0020] S3: Inspection of the second sealing layer glue coating area: Check the glue coating uniformity in the glue coating area to ensure that there are no defects such as missing glue, excessive glue coating, glue bubbles, etc. in the glue coating area;

[0021] S4: Drying of the glue coating area of ​​the second sealing layer: After the second sealing layer is dried at a temperature of 20°C to 40°C for about 2 hours, the surface is dry, and then it can be heated and sealed with the first sealing layer of the inner sealing strip;

[0022] S5: Heat, seal and cure the inner sealing strip; use a high-frequency welding machine or a hot-press welding machine to heat and seal the first sealing layer of the inner sealing strip and the second sealing layer of the material to be sealed. The heating temperature is 70-130°C and the time is 5s-10s to complete the sealing. The high-frequency welding machine needs to match the parameters such as the welding plate size, current and heating time to achieve the best sealing effect. After hot pressing, it needs to be placed in a room temperature environment (20°C-40°C) for 1d-2d to complete the curing of the inner sealing strip. For some uneven parts, heating tools such as hot air guns can also be used. The heating temperature is 70-130°C. After that, the sealed parts can be repeatedly rolled with rollers to enhance the sealing. The above-mentioned sealed materials also need to be placed in a room temperature environment (temperature 20°C-40°C) for 1d-2d to complete the curing of the inner sealing strip.

[0023] The above one or more technical solutions of the present invention have at least one or more of the following technical effects:

[0024] The inner sealing strip provided by the present invention can be used for multi-layer flexible composite materials: the weld seam is sealed by using an inner sealing strip, the inner sealing strip specifically consists of a protective layer, a gas barrier layer, an interface layer and a sealing layer, wherein the protective layer plays an aging protection role for the entire inner sealing strip; the gas barrier layer mainly plays a gas barrier role; the interface layer mainly plays a connecting role, connecting the gas barrier layer and the sealing layer; the sealing layer mainly plays a sealing role. The inner sealing strip in this method is particularly suitable for sealing the surface of fabrics with uneven surfaces and no adhesive layer on the surface, and of course it can also be used for sealing the inner surface of multi-layer flexible composite materials with films or adhesive layers. By sealing the inner surface of the multi-layer flexible composite material, the inner sealing strip is protected from the influence of external light, humidity, heat and other adverse environments; secondly, the material and construction process of the inner sealing strip are improved, and the surface is coated with adhesive and a hot-melt adhesive film with better heat-sealing processability is used to improve the sealing strength and durability of the inner sealing strip. This ensures that the inner sealing strip will not suffer fatigue damage after being exposed to high temperature for a long time and repeated bending and flexing, thereby avoiding damage to the inner sealing strip. The overall airtightness of the airbag made of multi-layer flexible composite materials is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 , schematic diagram of the inner sealing strip structure of a multi-layer flexible composite material.

[0026] Among them, 1-protective layer, 2-gas barrier layer, 3-connecting layer, 4-first sealing layer, 5-second sealing layer, 6-inner sealing strip. DETAILED DESCRIPTION

[0027] The embodiment of the present invention provides an inner sealing strip that can be used for a multi-layer flexible composite material and a method of using the same, which solves the problems of fatigue damage, inner sealing strip breakage, poor weld air tightness, etc. after long-term exposure to high temperature environment and repeated bending and flexing.

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments obtained. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0029] Example 1

[0030] An inner sealing strip comprises a protective layer, a gas barrier layer, an interface layer and a sealing layer from the outside to the inside. The multi-layer flexible composite material to be sealed comprises PVDF / EVOH functional film / glue / aromatic polyester fiber woven fabric / thermoplastic polyurethane TPU from the outside to the inside. The protective layer of the inner sealing strip is an aliphatic polyurethane material with a thickness of 0.5 μm. The protective layer is composed of 70 parts of polyurethane material, 15 parts of titanium dioxide, 5 parts of silicon dioxide and 10 parts of tris(4-phenylisocyanate)thiophosphate isocyanate curing agent; the gas barrier layer is a barrier polyurethane film with a three-layer structure, which comprises TPU, EVOH and TPU in sequence. The thickness distribution ratio of the three-layer film is 1:2:1, and the thickness of the gas barrier layer is 10 μm; the interface layer is a mixture of JQ-1 glue and JQ-4 glue with a mixing ratio of 1:1, which needs to be coated on the TPU film surface of the gas barrier layer for use. The first sealing layer is a polyurethane hot melt adhesive with a thickness of 15μm. The melting point of the hot melt adhesive is 100℃. The hot melt adhesive composition includes 85 parts of hot melt adhesive, 5 parts of white carbon black, and 10 parts of carbon black. The polyurethane hot melt adhesive is an aliphatic polyether polyurethane structure. The second sealing layer is formed by brushing the stirred water-based polyurethane adhesive and the matching curing agent on the area to be sealed. The water-based polyurethane adhesive and the curing agent are 100:6, and the thickness of the second sealing layer is 15μm. The specific application process includes: the first step, the second sealing layer adhesive is configured; the water-based polyurethane adhesive and the curing agent are configured in a mass ratio of 100:6, and mixed with a stirrer for 15 minutes; the configured water-based polyurethane adhesive is applied to the area to be sealed with a nylon brush for 2 times, and the adhesive application area is inspected and dried after being evenly applied. After drying for 2 hours, the surface dryness of the second sealing layer is confirmed. If the surface of the adhesive layer is dry and there is no stickiness, it is hot-pressed and sealed with the first sealing layer of the inner sealing strip. The heating temperature is 100°C and the hot-pressing time is 5 seconds. The hot-pressed sealed sample is placed at room temperature (temperature 20°C) for 1 day for curing. The sealing part was subjected to room temperature peeling, 2000 flexing and helium permeability tests, of which the peel strength was 15N / cm (GB 8808 Method A), and no defects such as breakage were found after 2000 flexings (QB / T 2714), and the helium permeability of the sealing area was 0.2L / m 2 ·24hr·0.1MPa(GB / T 1038).

[0031] Example 2

[0032] An inner sealing strip comprises a protective layer, a gas barrier layer, an interface layer and a sealing layer from the outside to the inside. Inner sealing strip: The flexible composite material comprises PVF / EVOH functional film / glue / polyarylate fiber woven fabric from the outside to the inside. The protective layer of the inner sealing strip is an aliphatic polyurethane material with a thickness of 1.0 μm. The protective layer is composed of 80 parts of polyurethane material, 10 parts of titanium dioxide, 5 parts of silicon dioxide and 5 parts of tris(4-phenylisocyanate)thiophosphate isocyanate curing agent; the gas barrier layer is a barrier polyurethane film with a thickness of 5 μm. It is a two-layer structure composed of two layers of TPU and EVOH films. The protective layer is located on the surface of the EVOH film in the gas barrier layer; the interface layer is JQ-1 glue, which needs to be coated on the TPU film surface of the gas barrier layer with a thickness of 1.0 μm. The interface layer connects the TPU film in the gas barrier layer and the first sealing layer. The first sealing layer is a polyurethane hot melt adhesive with a thickness of 12 μm. The melting point of the hot melt adhesive is 70°C. The hot melt adhesive composition includes 85 parts of hot melt adhesive, 5 parts of white carbon black, and 10 parts of carbon black. The polyurethane hot melt adhesive is an aliphatic polyether polyurethane structure. The stirred mixture of water-based polyurethane adhesive and curing agent is applied to the area to be sealed to form a second sealing layer. The ratio of water-based polyurethane adhesive to curing agent is 100:8, and the thickness of the second sealing layer is 40 μm. The specific application process includes: the first step is to configure the adhesive for the second sealing layer; configure the water-based polyurethane adhesive and the curing agent in a mass ratio of 100:8, and use a stirrer to mix them for 15 minutes; use a nylon brush to apply the configured water-based polyurethane adhesive to the area to be sealed, the number of times of application is 2, after the application is evenly done, the adhesive application area is checked and dried, and the drying time is 2h to 8h, the second sealing layer is confirmed to be dry, and hot pressing is performed with the first sealing layer of the inner sealing strip to form a sealing structure, the heating temperature is 100℃, the hot pressing time is 5s, the hot pressed sealed sample is placed in a room temperature environment (temperature 20℃~40℃) for 1d, and the sealing part is subjected to room temperature peeling, 3000 flexing, and airtightness performance tests, wherein the peel strength is 18N / cm (GB8808 method A), and no defects such as damage have been found after 3000 flexings after current inspection (QB / T 2714), the sealing area was tested for helium permeability, and the helium permeability was 0.5L / m 2 ·24hr·0.1MPa (GB / T 1038). The test piece sealed by the above sealing process was subjected to 56d solar radiation accelerated aging according to the test conditions of GJB 8177. The helium permeability of the weld of the material after aging was tested and found to be 0.6L / m 2 ·24hr·0.1MPa(GB / T 1038), the air tightness did not increase significantly.

Claims

1. An inner sealing strip that can be used for a multi-layer flexible composite material, characterized in that: The inner sealing strip is composed of a protective layer, a gas barrier layer, an interface layer and a sealing layer in sequence from the outside to the inside, and the protective layer, the gas barrier layer, the interface layer and the sealing layer are connected to each other.

2. The inner sealing strip applicable to multi-layer flexible composite materials according to claim 1, characterized in that: The protective layer is prepared from the following raw materials in parts by weight: 60 to 70 parts of polyurethane, 5 to 15 parts of titanium dioxide, 5 to 10 parts of silicon dioxide and 5 to 25 parts of isocyanate.

3. The inner sealing strip for multi-layer flexible composite material according to claim 2, characterized in that: The polyurethane is one or both of aromatic polyurethane and aliphatic polyurethane.

4. The inner sealing strip for multi-layer flexible composite material according to claim 2, characterized in that: The isocyanate is triphenylmethane triisocyanate, tri(4-phenylisocyanate)phosphorothioate or dimethyltriphenylmethane tetraisocyanate.

5. The inner sealing strip for multi-layer flexible composite materials according to claim 1, characterized in that: The gas barrier layer is a barrier modified polyurethane film.

6. The inner sealing strip for multi-layer flexible composite materials according to claim 5, characterized in that: The barrier modified polyurethane film has a three-layer structure, which comprises polyurethane TPU, ethylene-vinyl alcohol copolymer EVOH, and TPU in sequence, and the thickness ratio of the three-layer film is 1:2:

1.

7. The inner sealing strip for multi-layer flexible composite materials according to claim 5, characterized in that: The barrier modified polyurethane film is a two-layer structure, which is composed of polyurethane TPU and EVOH, and the thickness ratio of the two layers of film is 1:

2.

8. The inner sealing strip for multi-layer flexible composite materials according to claim 1, characterized in that: The interface layer is a polyisocyanate adhesive, and the polyisocyanate adhesive is one or two of JQ-1 adhesive, JQ-4 adhesive, Desmodur RF, Desmodur RFE, Desmodur R or Desmodur RE, wherein the mixing ratio of the two adhesive mixtures is 1:1-2.

9. The inner sealing strip for multi-layer flexible composite materials according to claim 1, characterized in that: The sealing layer consists of a first sealing layer and a second sealing layer; the first sealing layer is connected to the interface layer, and the second sealing layer is connected to the material to be sealed.

10. The inner sealing strip for multi-layer flexible composite material according to claim 9, characterized in that: The first sealing layer is prepared from the following raw materials in parts by weight: 70-85 parts of polyurethane hot melt adhesive; 5-10 parts of white carbon black; 5-25 parts of carbon black; wherein the polyurethane hot melt adhesive is prepared using aliphatic polyether polyurethane and IPDI, and the melting point of the polyurethane hot melt adhesive is 70°C to 130°C; the second sealing layer is prepared from the following raw materials in parts by weight: 100 parts of water-based polyurethane adhesive and 3-10 parts of curing agent.

11. An application method for a sealing strip inside a multi-layer flexible composite material as claimed in any one of claims 1 to 10, characterized in that: The steps include: S1: Preparation of adhesive for the second sealing layer of the inner sealing strip: prepare the water-based polyurethane adhesive and the curing agent according to a predetermined mass ratio, and mix them evenly with a stirrer for 15 to 30 minutes. When there is no sediment in the mixture, it can be judged that the mixture is evenly mixed; S2: Apply the second sealing layer: Apply the prepared water-based polyurethane adhesive to the area to be sealed with a nylon brush or a nylon bristle brush for at least 2 times. Dip the brush into the mixed adhesive and apply it to the area to be sealed. During the application process, apply the adhesive back and forth in a straight line until it is evenly applied. If shrinkage holes or bubbles appear on the surface during the application process, leave it in the air for about 2 minutes and then apply it with a brush until the shrinkage holes or bubbles disappear. S3: Inspection of the second sealing layer glue coating area: Check the uniformity of the glue coating area to ensure that there are no defects such as missing glue, excessive glue coating, glue bubbles, etc. in the coating area; S4: Drying of the glue coating area of ​​the second sealing layer: After the second sealing layer is dried at a temperature of 20℃~40℃ for about 2h, the surface is dry and the inner sealing strip can be heat-sealed; S5: Heat sealing and curing of inner sealing strip; use high-frequency welding machine or hot pressing welding machine to heat and seal the first sealing layer of the inner sealing strip and the second sealing layer glue coating area of ​​the material to be sealed. After hot pressing, place it at a temperature of 20℃~40℃ for 1d~2d to complete the curing of the inner sealing strip. For some uneven parts, you can also use a hot air gun or other heating tools for heat sealing. The heating temperature is 70~130℃. After heat sealing, you can use a roller to repeatedly roll the sealed part to enhance the sealing. The above-mentioned sealed materials also need to be placed at a temperature of 20℃~40℃ for 1d~2d to complete the curing of the inner sealing strip.

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