IV-type bottle pressure vessel inner container and forming process thereof

Abstract

The invention relates to the field of pressure gas cylinder processing and production, in particular to an IV-type cylinder pressure container inner container and a forming process thereof. The invention provides a forming process of a pressure container inner container, which comprises the following steps: adhering a glue film to the surface of a metal valve seat, injecting a plastic raw material into a mold, and carrying out rotational molding to obtain the pressure container inner container, the adhesive film comprises a bonding film and an adhesive layer arranged on one side of the bonding film, the temperature of rotational molding is larger than or equal to the viscosity onset temperature of the bonding film and smaller than or equal to the decomposition temperature of the bonding film, the adhesive layer is attached to the surface of the metal valve seat, the viscosity temperature interval of the adhesive layer is smaller than or equal to 35 DEG C, and the thickness of the adhesive layer accounts for 10%-70% of the thickness of the adhesive film. The adhesive film formed by the adhesive layer and the adhesive film is used for the forming process of the pressure container, the adhesive film can be adhered to the valve seat by utilizing the adhesive layer in the adhesive film in a normal-temperature or low-temperature environment, and the adhesive property between the inner container and the valve seat is remarkably improved by utilizing the adhesive film.

Description

Technical Field

[0001] The invention relates to the field of pressure gas cylinder processing and production, and in particular to a type IV pressure container liner and a molding process thereof. Background Art

[0002] As a clean energy solution with zero carbon emissions, hydrogen energy has attracted widespread attention. In particular, high-pressure gaseous hydrogen storage technology has become the focus of research due to its importance in the storage and transportation of hydrogen energy. Among them, the quality of pressure vessels has become a key factor affecting the development of hydrogen energy storage and transportation.

[0003] The pressure vessels for hydrogen storage and transportation are mainly type IV hydrogen storage bottles with plastic liner and carbon fiber full winding technology. The roto-molded liner structure of the type IV bottle includes two parts: the plastic liner and the aluminum valve seat. Currently, there are three main methods for connecting the plastic liner and the aluminum valve seat: (1) During the roto-molding process, the aluminum valve seat is connected to the plastic liner as an insert; (2) The aluminum valve seat and the liner are connected by threading or bonding; (3) Before the roto-molding process, glue or hot melt adhesive is applied to the surface of the aluminum valve seat to achieve bonding of the joint surface of the plastic liner and the aluminum valve seat during the roto-molding process. The above three methods can connect the plastic liner to the aluminum valve seat, but in actual use, the type IV bottle is prone to failure under high pressure due to the loose connection between the plastic liner and the aluminum valve seat. For example, after rotational molding is completed, the aluminum valve seat is connected to the plastic liner in the form of an insert. Since there is no adhesive between the non-polar plastic and the aluminum, a gap will be generated at the contact interface after the liner cools and shrinks and during subsequent use. This gap will cause relative displacement between the sealing surface and the valve seat after the Type IV bottle is pressurized, thereby affecting the sealing and reliability of the structure. When the aluminum valve seat is connected to the plastic liner by threading or bonding, due to the accuracy of rotational molding size control, there will inevitably be a certain gap or non-fitting phenomenon. At present, bonding the joint surface of the plastic liner and the insert aluminum valve seat during rotational molding is a relatively good solution, but the hot melt adhesive commonly used in the prior art is difficult to apply evenly and has poor thermal stability, resulting in non-fitting between the plastic liner and the aluminum valve seat. Secondly, there are volatiles when the liquid solvent adhesive is applied, which pollutes the environment and also has certain hazards to the operator. In addition, this method requires multiple treatments of the valve seat, which increases the difficulty of the process.

[0004] The prior art discloses a structure of an end valve seat for a composite gas cylinder, which uses a polyolefin film to cover the outer surface of the valve seat in the hot-pressing environment of the injection molding process, effectively improving the airtightness, reliability and safety of the end valve seat. However, since the temperature of the rotational molding process cannot reach the hot-pressing temperature of the injection molding process, the film is used in the rotational molding process to prepare a pressure vessel, resulting in poor adhesion between the liner and the valve seat, and the bonding environment is high temperature and high pressure, and cold adhesion is impossible. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of poor adhesion between the plastic liner and the metal valve seat in the prior art and the inability to adhere in a cold state, thereby providing a type IV bottle pressure container liner and its molding process.

[0006] On the one hand, the present invention provides a molding process for a pressure vessel liner, comprising the following steps: attaching a rubber film to the surface of a metal valve seat, injecting a plastic raw material into a mold, and performing rotational molding to obtain the pressure vessel liner;

[0007] The adhesive film includes an adhesive film and an adhesive layer arranged on one side of the adhesive film. The rotational molding temperature is greater than or equal to the adhesive onset temperature of the adhesive film and less than or equal to the decomposition temperature of the adhesive film. The adhesive layer is attached to the surface of the metal valve seat. The adhesive temperature range of the adhesive layer is less than or equal to 35°C, and the thickness of the adhesive layer accounts for 10%-70% of the thickness of the adhesive film.

[0008] In the present invention, the term tack onset temperature of the adhesive film is the lowest temperature at which the adhesive film exhibits tack, and above this temperature, the adhesive film has adhesion ability.

[0009] In the present invention, the term adhesive temperature range of the adhesive layer refers to a temperature range in which the adhesive layer produces an adhesive effect with the metal valve seat when the adhesive layer is adhered to the metal valve seat.

[0010] It should be noted that the adhesive film in the embodiment of the present invention is sticky between the stickiness onset temperature and the decomposition temperature, and the adhesive layer is sticky within the stickiness temperature range. When the temperature reaches any temperature value within the stickiness temperature range of the adhesive layer, the adhesive layer has adhesion ability and can produce adhesion with the adhesive film and the metal material.

[0011] Preferably, the viscosity temperature range of the adhesive layer in the embodiment of the present invention includes a temperature below 35°C, and more preferably, the viscosity temperature range of the adhesive layer includes 0°C-35°C.

[0012] The method for determining the viscosity onset temperature of an adhesive film or the viscosity temperature range of an adhesive layer in an embodiment of the present invention is as follows: the material of the adhesive film or the adhesive layer is covered on the surface of an aluminum sheet, and the sheets are kept in ovens at different temperatures for 15 minutes. After the sheets are taken out, the peel strength between the adhesive film or the adhesive layer and the aluminum sheet at different temperatures is determined according to the GB / T 2790-1995 test standard. The lowest temperature at which the peel strength between the adhesive film and the aluminum sheet reaches a preset peel strength is set as the viscosity onset temperature of the adhesive film, and the temperature range at which the peel strength between the adhesive layer and the aluminum sheet reaches a preset peel strength is set as the viscosity temperature range of the adhesive layer.

[0013] The adhesive layer provided by each embodiment of the present invention has a viscosity temperature range of 0°C-35°C, and can exhibit viscosity at room temperature (0°C-35°C) without additional heating treatment.

[0014] In the embodiment of the present invention, the preset peel strength between the adhesive layer and the aluminum sheet is set to 10 N / cm, and in the embodiment of the present invention, the preset peel strength between the adhesive film and the aluminum sheet is set to 15 N / cm. It should be noted that the present invention does not limit the specific numerical value of the preset peel strength, and it can be set according to the requirements of the specific application scenario.

[0015] In some embodiments, the step of attaching the adhesive film to the surface of the metal valve seat includes applying an adhesive to the surface of the metal valve seat to form an adhesive layer, and sticking the adhesive film to the side of the adhesive layer facing away from the metal valve seat, or includes applying an adhesive on the adhesive film to form an adhesive film, and sticking the adhesive layer in the adhesive film to the surface of the metal valve seat.

[0016] In some of the embodiments, the temperature at which the adhesive is coated on the surface of the metal valve seat or the adhesive layer in the adhesive film is adhered to the surface of the metal valve seat is 0°C-35°C.

[0017] In some of the embodiments, before the adhesive film is attached to the surface of the metal valve seat, the method further includes anodizing and / or pickling the metal valve seat.

[0018] In some embodiments, the metal valve seat is an aluminum valve seat.

[0019] In some of the embodiments, the plastic raw material is selected from at least one of polyethylene (including modified polyethylene) or polyamide (including modified polyamide).

[0020] Preferably, the plastic raw material complies with standard GB / T 42612-2023.

[0021] In some of the embodiments, the plastic liner is formed by a programmed temperature increase method during the rotational molding process.

[0022] Preferably, the specific steps of the programmed temperature increase are: increasing the programmed temperature to a first temperature within a first time, maintaining the temperature at the first temperature for a second time, increasing the programmed temperature from the first temperature to a second temperature within a third time, and maintaining the temperature at the second temperature for a fourth time.

[0023] The first temperature T1 satisfies the relationship t1≤T1≤t1+20, t1 is the viscosity starting temperature of the adhesive film,

[0024] The second temperature T2 satisfies the relationship t2≤T2≤t3+20, t2 is the decomposition temperature of the adhesive layer, and t3 is the decomposition temperature of the adhesive film.

[0025] Preferably, the first time is 10-30 min, the second time is 5-15 min, the third time is 5-15 min, and the fourth time is 5-30 min.

[0026] In some of the embodiments, the temperature of the valve seat during the rotational molding process is 5-30° C. higher than the rotational molding process temperature.

[0027] In some embodiments, the temperature of the valve seat is controlled by fan air heating or electric heating.

[0028] In some of the embodiments, an air circuit is added to heat the valve seat so that the temperature of the valve seat is 5° C.-30° C. higher than the rotational molding temperature.

[0029] In some embodiments, in order to avoid continuous temperature increase during the rotational molding process, which causes the rotational molding temperature to reach or approach the decomposition temperature of the adhesive film and causes the bonding effect of the adhesive film to decay, the second temperature in the rotational molding process is lower than the decomposition temperature of the adhesive film, and the holding time of the second temperature is controlled.

[0030] For example, when the adhesive film in the film is polyethylene (the adhesive film has an effective temperature of 150°C) and the adhesive is vinyl triethoxysilane, the adhesive film in the film will oxidize and lose its viscosity when kept at 210°C for 40 minutes (during the operation, after the heating module is turned off, the temperature will rise to 230°C in a short time). Therefore, in order to prevent the bonding effect of the adhesive film from attenuating, the second temperature of the rotational molding process needs to be controlled within the range of 155-230°C and it is necessary to ensure that the film is exposed to a temperature greater than 210°C for no more than 30 minutes during the entire rotational molding process.

[0031] In some of the embodiments, the rotation speed ratio during the rotational molding process is (4-20):1; the rotation speed ratio is the ratio of the rotational velocity of the rotational molding mold along the mold axis to the rotational angular velocity of the rotational molding machine arm.

[0032] In some of the embodiments, the program temperature of the rotational molding during the rotational molding process is measured by an infrared temperature measurement module or a wireless temperature measurement module.

[0033] In some embodiments, the molding process further comprises a step of cooling the pressure vessel after rotational molding.

[0034] Preferably, the cooling method is at least one of air cooling and water cooling.

[0035] More preferably, the air cooling speed is 500 rpm-2000 rpm, and the time is 40 min-50 min.

[0036] In some embodiments, the decomposition temperature of the adhesive layer is greater than the bonding effectiveness temperature of the adhesive film.

[0037] In some embodiments, the decomposition temperature of the adhesive layer is lower than the decomposition temperature of the adhesive film.

[0038] Through the method for determining the viscosity onset temperature provided by the present invention, a material that exhibits viscosity with both the metal material and the adhesive film at 0-35° C. is selected as the adhesive for forming the adhesive layer.

[0039] In some embodiments, the adhesive comprises a silane coupling agent. Preferably, the material of the adhesive is selected from at least one of vinyl triethoxysilane, γ-chloropropyl trichlorosilane, and chloromethyl triethoxysilane. The viscosity onset temperature of the adhesive material is less than or equal to 35°C.

[0040] In some embodiments, the adhesive film comprises a polymer compound. Preferably, the material of the adhesive film is selected from at least one of polyolefin, ethylene-vinyl acetate copolymer, and maleic anhydride grafted polyethylene.

[0041] In some embodiments, the thickness of the adhesive film is 0.02 mm-1 mm.

[0042] The viscosity onset temperature of the adhesive film is measured by the viscosity onset temperature measurement method provided by the present invention and is between 99° C. and 230° C.

[0043] In some embodiments, the decomposition temperature of the adhesive layer is 155°C-230°C.

[0044] On the other hand, the present invention provides a pressure vessel liner, which is made by the above-mentioned pressure vessel liner molding process.

[0045] The technical solution of the present invention has the following beneficial effects:

[0046] 1. The present invention provides a molding process for a pressure vessel liner, comprising the following steps: attaching a film to the surface of a metal valve seat, injecting a plastic raw material into a mold, and performing rotational molding to obtain a pressure vessel liner; the film comprises an adhesive film and an adhesive layer arranged on one side of the adhesive film, the rotational molding temperature is greater than or equal to the viscosity onset temperature of the adhesive film and less than or equal to the decomposition temperature of the adhesive film, the adhesive layer is attached to the surface of the metal valve seat, the viscosity temperature range of the adhesive layer is less than or equal to 35°C, and the thickness of the adhesive layer accounts for 10%-70% of the thickness of the film. The present invention forms an adhesive film with an adhesive layer and an adhesive film for a molding process of a pressure vessel, and can use the adhesive layer in the film to achieve the bonding of the adhesive film to the valve seat at room temperature or low temperature, and then by controlling the rotational molding temperature between the viscosity onset temperature of the adhesive film and the decomposition temperature of the adhesive film, the adhesive film is used to significantly improve the bonding performance between the liner and the valve seat, so that the peel strength between the liner and the valve seat is higher. At the same time, the present invention controls the thickness of the adhesive layer, improves the firmness of the adhesion between the inner liner and the valve seat, and further improves the peeling strength between the inner liner and the valve seat.

[0047] 2. The present invention provides a molding process for a pressure vessel liner, wherein a program temperature rise method is used to mold the plastic liner during the rotational molding process. Preferably, the program temperature rise specifically comprises raising the program temperature to a first temperature within a first time, keeping the temperature at the first temperature for a second time, raising the program temperature from the first temperature to a second temperature within a third time, and keeping the temperature at the second temperature for a fourth time. The first temperature T1 satisfies the relationship t1≤T1≤t1+20, t1 is the viscosity onset temperature of the adhesive film, and the second temperature T2 satisfies the relationship t2≤T2≤t3+20, t2 is the decomposition temperature of the adhesive layer, and t3 is the decomposition temperature of the adhesive film. The present invention uses a program temperature rise method for rotational molding, and sets two temperatures during the rotational molding process. The rotational molding temperature is first raised to the adhesion onset temperature of the adhesive film, and the adhesive film is used to strengthen the adhesion between the plastic liner and the valve seat. Then, the temperature is raised to the decomposition temperature of the adhesive layer. After the adhesive layer is decomposed, the adhesive film is used to further strengthen the adhesion between the valve seat and the liner, thereby improving the peel strength between the valve seat and the liner.

[0048] 3. In the molding process of a pressure vessel liner provided by the present invention, the decomposition temperature of the adhesive layer is greater than the bonding effective temperature of the adhesive film. The present invention selects the decomposition temperature of the adhesive layer to be greater than the bonding effective temperature of the adhesive film to ensure that the adhesive layer is not decomposed before the adhesive film produces adhesive properties, thereby maintaining the adhesiveness of the valve seat and the plastic liner.

[0049] 4. The present invention provides a molding process for a pressure vessel liner, wherein the decomposition temperature of the adhesive layer is lower than the decomposition temperature of the adhesive film. The present invention avoids the adhesive film from decomposing before the adhesive layer by selecting an adhesive layer whose decomposition temperature is lower than the decomposition temperature of the adhesive film. On the one hand, the adhesive film decomposition leads to poor adhesion, and on the other hand, the undecomposed adhesive layer causes a gap or relative displacement between the metal valve seat and the plastic liner, thereby reducing the sealing between the plastic liner and the metal valve seat.

[0050] 5. The present invention provides a molding process for a pressure vessel liner, wherein the adhesive comprises a silane coupling agent. The present invention utilizes the alkyl group in the silane coupling agent to react with the metal to achieve adhesion to the metal valve seat, and utilizes the carbon chain of the silane coupling agent to react with the adhesive film to achieve adhesion to the adhesive film, which can not only meet the cold adhesion requirements, but also improve the peel strength between the metal valve seat and the plastic liner.

[0051] 6. The present invention provides a molding process for a pressure vessel liner, which realizes the bonding between the metal valve seat and the interface of the liner during the rotational molding process, reduces the difficulty of the process, saves the time of the entire rotational molding process, optimizes the process flow, and improves production efficiency. Compared with the insert connection method and the threaded connection method, the valve seat of the present invention is more tightly bonded to the liner, and will not cause gaps and relative displacement between the sealing surface and the valve seat after the gas cylinder is pressurized; and compared with the bonding method of multiple heating using hot melt adhesive or solvent adhesive, the process of the present invention is simpler, the bonding thickness is more uniform, and there is no toxic volatiles. In addition, the bonding effect of the adhesive film is more stable after experiencing the high temperature environment of rotational molding.

[0052] 7. The pressure vessel liner provided by the present invention has strong adhesion between the liner and the valve seat, and good peel strength between the liner and the valve seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 is a schematic diagram of the structure of the adhesive film in Example 1 of the present invention;

[0055] Figure 2 This is a graph showing the relationship between the thickness ratio of the adhesive layer in the adhesive film and the peel strength between the inner liner and the metal valve seat in Experimental Example 2 of the present invention;

[0056] Reference numerals:

[0057] 1-adhesive film; 2-adhesive layer. DETAILED DESCRIPTION

[0058] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0059] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0060] The plastic liner material of the embodiment of the present invention is taken as polyethylene powder (molecular weight 190000, particle size 40-100 mesh) as an example.

[0061] Preparation of solvent glue (1) in the comparative example and experimental example of the present invention: prepared by conventional technical means in the art, the solute is maleic anhydride modified polyethylene, and the solvent is xylene. Preparation of solvent glue (2): prepared by conventional technical means in the art, the solute is ethylene-vinyl acetate copolymer, and the solvent is carbon tetrachloride. Solvent glue (1) and solvent glue (2) were prepared with the assistance of Sichuan University.

[0062] The hot melt adhesive is EVA (ethylene / vinyl acetate copolymer) hot melt adhesive purchased from Arkema.

[0063] Preparation Example 1

[0064] This preparation example provides a method for preparing a film, and the specific steps and parameters are as follows:

[0065] At 27° C., an adhesive is applied to one side of an adhesive film 1 to form an adhesive layer 2. The adhesive layer and the adhesive film constitute an adhesive film. The structure of the adhesive film is as follows: Figure 1 shown.

[0066] The adhesive film used in this preparation example is a polyethylene film (from Nantong Guoao New Materials Co., Ltd.), with a thickness of 0.09 mm and a material of polyethylene. The bonding temperature of polyethylene is 150° C. and the decomposition temperature is 240° C.

[0067] The adhesive used in this preparation example is vinyl triethoxysilane, and the thickness of the formed adhesive layer is 0.01 mm. The decomposition temperature of vinyl triethoxysilane is 161°C.

[0068] The viscosity temperature range of the adhesive layer in this preparation example is 0°C-35°C.

[0069] Preparation Example 2

[0070] This preparation example provides a method for preparing a film, and the specific steps and parameters are as follows:

[0071] At 25° C., an adhesive is coated on one side of the adhesive film to form an adhesive layer, and the adhesive layer and the adhesive film constitute an adhesive film.

[0072] The adhesive film used in this preparation example is an ethylene-vinyl acetate copolymer film (from Nantong Guoao New Materials Co., Ltd., molecular weight 342), the thickness of the adhesive film is 0.09 mm, the material is ethylene-vinyl acetate copolymer, the bonding onset temperature of ethylene-vinyl acetate copolymer is 99° C., and the decomposition temperature is 230° C.

[0073] The adhesive used in this preparation example is γ-chloropropyltrichlorosilane, and the thickness of the formed adhesive layer is 0.01 mm. The decomposition temperature of γ-chloropropyltrichlorosilane is 181°C.

[0074] The viscosity temperature range of the adhesive layer in this preparation example is 0°C-35°C.

[0075] Preparation Example 3

[0076] This preparation example provides a method for preparing a film, and the specific steps and parameters are as follows:

[0077] At 30° C., an adhesive is coated on one side of the adhesive film to form an adhesive layer, and the adhesive layer and the adhesive film constitute an adhesive film.

[0078] The adhesive film used in this preparation example is a maleic anhydride grafted polyethylene film (from Nantong Guoao New Materials Co., Ltd., molecular weight 378), the thickness of the adhesive film is 0.09 mm, the material is maleic anhydride grafted polyethylene, the bonding temperature of maleic anhydride grafted polyethylene is 125°C, and the decomposition temperature is 230°C.

[0079] The adhesive used in this preparation example is chloromethyltriethoxysilane, and the thickness of the formed adhesive layer is 0.01 mm. The decomposition temperature of chloromethyltriethoxysilane is 174°C.

[0080] The viscosity temperature range of the adhesive layer in this preparation example is 0°C-35°C.

[0081] Preparation Example 4

[0082] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those of Preparation Example 1, except that the thickness of the adhesive layer is 0.02 mm and the thickness of the adhesive film is 0.08 mm.

[0083] Preparation Example 5

[0084] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those in Preparation Example 1, except that the thickness of the adhesive layer is 0.03 mm and the thickness of the adhesive film is 0.07 mm.

[0085] Preparation Example 6

[0086] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those of Preparation Example 1, except that the thickness of the adhesive layer is 0.04 mm, and the thickness of the adhesive film is 0.06 mm.

[0087] Preparation Example 7

[0088] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those in Preparation Example 1, except that the thickness of the adhesive layer is 0.05 mm and the thickness of the adhesive film is 0.05 mm.

[0089] Preparation Example 8

[0090] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those in Preparation Example 1, except that the thickness of the adhesive layer is 0.06 mm and the thickness of the adhesive film is 0.04 mm.

[0091] Preparation Example 9

[0092] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those of Preparation Example 1, except that the thickness of the adhesive layer is 0.07 mm and the thickness of the adhesive film is 0.03 mm.

[0093] Preparation Example 10

[0094] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those of Preparation Example 1, except that the thickness of the adhesive layer is 0.01 mm and the thickness of the adhesive film is 0.01 mm.

[0095] Preparation Example 11

[0096] This preparation example provides a method for preparing an adhesive film. The specific steps and parameters are the same as those in Example 1, except that the thickness of the adhesive layer is 0.5 mm and the thickness of the adhesive film is 0.5 mm.

[0097] Example 1

[0098] This embodiment provides a molding process for a pressure vessel liner, wherein the pressure vessel liner is a type IV bottle rotomolding liner, and the rotomolding equipment is an L-arm rotomolding machine. The specific steps and parameters are as follows:

[0099] (1) Clean the surface of the aluminum valve seat with a 6% vol nitrate aqueous solution;

[0100] (2) Under a temperature of 25° C., the adhesive film prepared in Preparation Example 1 was adhered to the sealing surface of the aluminum valve seat, and then the aluminum valve seat was placed on a mold, and an air path was added to heat the valve seat.

[0101] (3) Polyethylene powder (average molecular weight of 190,000, average particle size of 80 mesh) was injected into the mold for rotational molding, the mold rotation rate was adjusted to 20 rad / s, the revolution angular velocity was adjusted to 1 rad / s, the mold temperature was increased from 25°C to 150°C (first temperature T1) within 20 min by using a programmed temperature increase method, and kept at 150°C for 10 min; then the temperature was increased from 150°C to 210°C (second temperature T2) within 10 min, and kept at 210°C for 5 min.

[0102] During the entire rotational molding process, the temperature of the aluminum valve seat is kept 20°C higher than the rotational molding temperature by adding an air path to avoid bubbles in the filler due to temperature difference. The rotational molding temperature is detected by an infrared temperature measurement module. When the temperature reaches 210°C and is kept warm for 5 minutes, the heating module is turned off and air cooling is used. After cooling for 50 minutes at a fan speed of 1000 rpm, the mold is removed to obtain the IV type bottle rotational molded liner.

[0103] Example 2

[0104] This embodiment provides a molding process for a pressure vessel liner, wherein the pressure vessel liner is a type IV bottle rotomolding liner, and the rotomolding equipment is an L-arm rotomolding machine. The specific steps and parameters are as follows:

[0105] (1) Clean the surface of the aluminum valve seat with a 6% vol nitrate aqueous solution;

[0106] (2) Under a temperature of 25° C., the adhesive film prepared in Preparation Example 2 was adhered to the sealing surface of the aluminum valve seat, and then the aluminum valve seat was placed on a mold, and an air path was added to heat the valve seat.

[0107] (3) Polyethylene powder (average molecular weight 190,000, average particle size 40 mesh) was injected into the mold for rotational molding, the mold rotation rate was adjusted to 20 rad / s, the revolution angular velocity was adjusted to 1 rad / s, the mold temperature was increased from 25°C to 100°C (first temperature T1) within 20 min by using a programmed temperature increase method, and kept at 100°C for 10 min; then the temperature was increased from 100°C to 200°C (second temperature T2) within 10 min, and kept at 200°C for 5 min.

[0108] During the entire rotational molding process, the temperature of the aluminum valve seat is kept 20°C higher than the rotational molding temperature by adding an air path to avoid bubbles in the filler due to temperature difference. The rotational molding temperature is detected by an infrared temperature measurement module. When the temperature reaches 200°C and is kept warm for 5 minutes, the heating module is turned off and air cooling is used. After cooling for 50 minutes at a fan speed of 1000 rpm, the mold is removed to obtain the IV type bottle rotational molded liner.

[0109] Example 3

[0110] This embodiment provides a molding process for a pressure vessel liner, wherein the pressure vessel liner is a type IV bottle rotomolding liner, and the rotomolding equipment is an L-arm rotomolding machine. The specific steps and parameters are as follows:

[0111] (1) Clean the surface of the aluminum valve seat with a 6% vol nitrate aqueous solution;

[0112] (2) Under a temperature of 25° C., the adhesive film prepared in Preparation Example 3 was adhered to the sealing surface of the aluminum valve seat, and then the aluminum valve seat was placed on a mold, and an air path was added to heat the valve seat.

[0113] (3) Polyethylene powder (average molecular weight 190,000, average particle size 100 mesh) was injected into the mold for rotational molding, the mold rotation rate was adjusted to 20 rad / s, the revolution angular velocity was adjusted to 1 rad / s, the mold temperature was increased from 25°C to 135°C (first temperature T1) within 20 min by using a programmed temperature increase method, and kept at 135°C for 10 min; then the temperature was increased from 135°C to 200°C (second temperature T2) within 10 min, and kept at 200°C for 5 min.

[0114] During the entire rotational molding process, the temperature of the aluminum valve seat is kept 20°C higher than the rotational molding temperature by adding an air path to avoid bubbles in the filler due to temperature difference. The rotational molding temperature is detected by an infrared temperature measurement module. When the temperature reaches 200°C and is kept warm for 5 minutes, the heating module is turned off and air cooling is used. After cooling for 50 minutes at a fan speed of 1000 rpm, the mold is removed to obtain the IV type bottle rotational molded liner.

[0115] Embodiment 4 to Embodiment 11

[0116] This embodiment provides a series of molding processes for pressure vessel liners, wherein the pressure vessel liners are type IV bottle rotational molded liners, and the specific steps and parameters are the same as those in Example 1, except that the films prepared in Preparation Examples 4-11 are used to replace the film prepared in Example 1 in step (2).

[0117] Example 12

[0118] This embodiment provides a molding process for a pressure vessel liner, and the specific steps and parameters are the same as those in Embodiment 1, except that the temperature in step (2) is 35°C.

[0119] Example 13

[0120] This embodiment provides a molding process for a pressure vessel liner, and the specific steps and parameters are the same as those in Embodiment 1, except that the temperature in step (2) is 0°C.

[0121] Embodiment 14

[0122] The present embodiment provides a forming process for a pressure vessel liner, wherein the specific steps and parameters are the same as those of Embodiment 1, except that in step (1), an aluminum alloy valve seat is used as an anode and placed in a sulfuric acid electrolyte solution, and an electric current is applied at 20° C. for 20 minutes to form an aluminum oxide film on its surface, and then the anodized aluminum alloy valve seat is immersed in 90° C. hot water for 20 minutes for sealing.

[0123] Embodiment 15

[0124] The present embodiment provides a molding process for a pressure vessel liner, and the specific steps and parameters are the same as those of Example 1, except that, in step (2), the adhesive in Preparation Example 1 is applied to the surface of the aluminum valve seat at 25°C, and the thickness of the adhesive layer is 0.01 mm. Then, an adhesive film is attached to the adhesive surface, and the thickness of the adhesive film is 0.09 mm. The aluminum valve seat is placed on the mold, and an air path is added to heat the valve seat.

[0125] Comparative Example 1

[0126] The present comparative example provides a molding process for a pressure vessel liner, wherein the pressure vessel liner is a type IV bottle rotational molded liner, and the specific steps and parameters are the same as those in Example 1, except that a solvent glue (1) is used to replace the glue film in step (2). The specific steps are as follows: (2) the solvent glue (1) is heated in a 60°C water bath until it is completely liquefied and then brushed on the surface of an aluminum valve seat, and the temperature of the aluminum sheet is maintained at 65±5°C during the brushing process. After coating, the aluminum valve seat is placed in an environment of 80°C to wait for the solvent to evaporate. After evaporation, a layer of polyethylene powder is sprinkled on the glue surface, and the aluminum valve seat is placed on a mold, and an air path is added to heat the valve seat.

[0127] In this comparative example, the solvent glue (1) is a mixed solution of maleic anhydride-modified polyethylene (molecular weight 378.33) as solute and xylene as solvent, and the mass fraction of the solute in the solvent glue is 3.6%.

[0128] Comparative Example 2

[0129] The present comparative example provides a molding process for a pressure vessel liner, wherein the pressure vessel liner is a type IV bottle rotational molded liner, and the specific steps and parameters are the same as those in Example 1, except that a solvent glue (2) is used to replace the glue film in step (2), specifically (2) the solvent glue (2) is heated in a 100°C oil bath until it is completely liquefied and then brushed on the surface of an aluminum valve seat, and the temperature of the aluminum valve seat is maintained at 105±5°C during the brushing process. After coating, the aluminum valve seat is placed in an environment of 120°C to wait for the solvent to evaporate, and after evaporation, a layer of polyethylene powder is sprinkled on the surface of the aluminum sheet, the aluminum valve seat is placed on a mold, and an air path is added to heat the valve seat.

[0130] The solvent glue in this comparative example was prepared with the assistance of Sichuan University, using ethylene-vinyl acetate copolymer as the solute and carbon tetrachloride as the solvent. The mass fraction of the solute in the solvent glue (2) was 4%.

[0131] Comparative Example 3

[0132] The present comparative example provides a molding process for a pressure vessel liner, wherein the pressure vessel liner is a type IV bottle rotationally molded liner, and the specific steps and parameters are the same as those in Example 1, except that a hot melt adhesive is used instead of the adhesive film in step (2). Specifically, (2) the hot melt adhesive is heated to 150°C until it is completely liquefied and then brushed on the surface of an aluminum valve seat, and the temperature of the aluminum valve seat is maintained at 105±5°C during the brushing process. After coating, the aluminum sheet is placed in an environment of 120°C to wait for the hot melt adhesive to evaporate. After evaporation, a layer of polyethylene powder is sprinkled on the surface of the aluminum valve seat, and the aluminum valve seat is placed on a mold, and an air path is added to heat the valve seat.

[0133] The hot melt adhesive in this comparative example is EVA (ethylene / vinyl acetate copolymer) hot melt adhesive purchased from Arkema.

[0134] Comparative Example 4

[0135] This comparative example provides a molding process for a pressure vessel liner, wherein the pressure vessel liner is a type IV bottle rotational molded liner, and the specific steps and parameters are the same as those in Example 1, except that the film is prepared by the following preparation method:

[0136] At 27° C., an adhesive is coated on one side of the adhesive film to form an adhesive layer, and the adhesive layer and the adhesive film constitute an adhesive film.

[0137] The adhesive film used in this preparation example is a polyethylene film (from Nantong Guoao New Materials Co., Ltd.), with a thickness of 0.02 mm and a material of polyethylene. The bonding temperature of polyethylene is 150° C. and the decomposition temperature is 240° C.

[0138] The adhesive used in this preparation example is vinyl triethoxysilane, the thickness of the formed adhesive layer is 0.08 mm, and the decomposition temperature of vinyl triethoxysilane is 161°C.

[0139] Comparative Example 5

[0140] This comparative example provides a molding process for a pressure vessel liner, and the pressure vessel liner is a type IV bottle rotational molded liner. The specific steps and parameters are the same as those of comparative example 4, except that the thickness of the adhesive layer is 0.09 mm and the thickness of the adhesive film is 0.01 mm.

[0141] Comparative Example 6

[0142] This comparative example provides a molding process for a pressure vessel liner, and the pressure vessel liner is a type IV bottle rotational molded liner. The specific steps and parameters are the same as those of comparative example 4, except that the thickness of the adhesive layer is 0.05 mm and the thickness of the adhesive film is 0.95 mm.

[0143] Comparative Example 7

[0144] This comparative example provides a molding process for a pressure vessel liner, and the pressure vessel liner is a type IV bottle rotational molded liner. The specific steps and parameters are the same as those of comparative example 4, except that the thickness of the adhesive layer is 0.95 mm and the thickness of the adhesive film is 0.05 mm.

[0145] Experimental Example 1

[0146] The simulation test method was used to test the operability of Preparation Example 1 and the glue adhesion material in the pressure vessel molding process, and the thermal stability of the adhesive film and the uniformity of the bonding interface were evaluated and the peel strength test was performed.

[0147] 1.1. Material preparation

[0148] The adhesive film prepared in Preparation Example 1 was adhered to an aluminum sheet, which was recorded as Test Sample 1;

[0149] At 160° C., the adhesive film provided in Preparation Example 1 (adhesive film thickness of 0.1 mm) was adhered to an aluminum sheet, and then a layer of polyethylene powder was sprinkled on the surface of the adhesive film, which was recorded as test sample 2;

[0150] Solvent glue (the same as solvent glue (1) provided in comparative example 1) was heated in a 60°C water bath until completely liquefied and then brushed on the surface of the aluminum sheet. During the brushing process, the temperature of the aluminum sheet was maintained at 65±5°C. After coating, the aluminum sheet was placed in an environment of 80°C to wait for the solvent to evaporate completely, forming an adhesive film with a thickness of 0.1 mm. After the evaporation, a layer of polyethylene powder was sprinkled on the surface of the adhesive film, which was recorded as test sample 3;

[0151] Solvent glue (the same as solvent glue (2) provided in comparative example 2) was heated in an oil bath at 100°C until completely liquefied and then brushed on the surface of the aluminum sheet. During the brushing process, the temperature of the aluminum sheet was maintained at 105±5°C. After coating, the aluminum sheet was placed in an environment at 120°C to wait for the solvent to evaporate completely, forming an adhesive film with a thickness of 0.1 mm. After the evaporation, a layer of polyethylene powder was sprinkled on the surface of the adhesive film, which was recorded as test sample 4;

[0152] The hot melt adhesive (the same as the hot melt adhesive provided in Comparative Example 3) was heated at 150°C until it was completely liquefied and then brushed on the surface of the aluminum sheet. During the brushing process, the temperature of the aluminum sheet was maintained at 105±5°C. After coating, the aluminum sheet was placed in an environment of 120°C to wait for the hot melt adhesive to evaporate, forming an adhesive film with a thickness of 0.1 mm. After evaporation, a layer of polyethylene powder was sprinkled on the surface of the adhesive film, which was recorded as test sample 5.

[0153] 1.2 Test Method

[0154] Thermal stability test: In a test environment of 220°C, simulating the highest temperature reached in the mold during rotational molding, test samples 1-5 were baked in an oven for 12 minutes and then taken out to observe whether the adhesive film or rubber film is aged, peeled off, or has decreased bonding performance. If any of these abnormalities occurs, the adhesive material is judged to have poor thermal stability during rotational molding.

[0155] The peel strength test between the plastic liner and the metal valve seat refers to the GB / T 2790-1995 test standard. An electronic universal testing machine is used to test the 90° peel strength of the sample, and the peel speed is fixed at 100mm / min.

[0156] 1.3 Results Analysis

[0157] Table 1 Test results of each test sample

[0158]

[0159]

[0160] According to the measurement results in Table 1, compared with test samples 3-5, in terms of the bonding effect on aluminum sheets by using other solvent glue composite adhesive films, the adhesive film provided by the preparation example of the present invention has a uniform peel strength bonding interface, high peel strength, and good thermal stability. Compared with test sample 2 that directly uses an adhesive film, the adhesive film (test sample 1) provided by the present invention has a simple preparation method and a simple molding process, and can achieve adhesion in a cold state.

[0161] Experimental Example 2

[0162] The peel strength between the plastic liner and the metal valve seat of the IV-type bottle rotational molded liner prepared in Examples 1-15 and Comparative Examples 1-7 was tested.

[0163] Test method for peel strength: refer to GB / T 2790-1995 test standard, use electronic universal testing machine to test the 90° peel strength of the sample, the peel speed is fixed at 100mm / min, and the test results are shown in Table 2.

[0164] Table 2 Test results of peel strength between liner and valve seat

[0165]

[0166]

[0167]

[0168] according to Figure 2As can be seen from the results in Table 2, compared with Comparative Examples 1 and 3-7, the adhesive film formed by the adhesive and the adhesive film in the present invention can greatly improve the peel strength of the rotationally molded liner. At the same time, compared with Comparative Examples 1-3, the present invention can achieve the adhesion between the adhesive film and the liner and the metal valve seat in a cold state by introducing an adhesive, thereby simplifying the molding process of the pressure vessel and improving the process efficiency.

[0169] Furthermore, in the process of preparing the rotational molded liner of type IV bottle of the present invention, it is found that when the thickness of the adhesive exceeds the thickness of the adhesive film, a small amount of unsuccessfully bonded air bubbles will exist on the bonding surface, resulting in reduced peel strength. Therefore, the adhesive needs to be as thin as possible while being able to achieve cold bonding. However, when the thickness of the adhesive is less than 10% of the thickness of the film, the cold bonding is not firm and falls off during installation and rotational molding. When the thickness of the adhesive is greater than 90% of the thickness of the film, the decomposition and volatilization is not complete and there are a large number of bubbles, which further affects the bonding effect. Therefore, the film provided in the embodiment of the present invention has better peel strength performance when the adhesive thickness is 10-50% of the film thickness.

[0170] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A molding process for a pressure vessel liner, characterized in that: The method comprises the following steps: attaching the adhesive film to the surface of the metal valve seat, injecting the plastic raw material into the mold, and performing rotational molding to obtain the pressure vessel liner; The adhesive film includes an adhesive film and an adhesive layer arranged on one side of the adhesive film. The temperature of the rotational molding is greater than or equal to the adhesive onset temperature of the adhesive film and less than or equal to the decomposition temperature of the adhesive film. The adhesive layer is attached to the surface of the metal valve seat. The adhesive temperature range of the adhesive layer is less than or equal to 35°C, and the thickness of the adhesive layer accounts for 10%-70% of the thickness of the adhesive film.

2. The molding process of the pressure vessel liner according to claim 1, characterized in that: The step of attaching the adhesive film to the surface of the metal valve seat includes applying an adhesive to the surface of the metal valve seat to form an adhesive layer, and attaching the adhesive film to a side of the adhesive layer away from the metal valve seat. or, The method comprises the following steps: coating an adhesive on the adhesive film to form an adhesive film, and adhering the adhesive layer in the adhesive film to the surface of the metal valve seat.

3. The molding process of the pressure vessel liner according to claim 2, characterized in that: The temperature at which the adhesive is coated on the surface of the metal valve seat or the adhesive layer in the adhesive film is adhered to the surface of the metal valve seat is 0°C-35°C.

4. The molding process of the pressure vessel liner according to any one of claims 1 to 3, characterized in that: Before attaching the adhesive film to the surface of the metal valve seat, the step of anodizing and / or pickling the metal valve seat is also included; and / or, The metal valve seat is an aluminum valve seat; and / or, The plastic raw material is selected from at least one of polyethylene, modified polyethylene, polyamide and modified polyamide; and / or, The adhesive comprises a silane coupling agent; and / or, The adhesive film includes a polymer compound.

5. The molding process of the pressure vessel liner according to any one of claims 1 to 4, characterized in that: In the process of rotational molding, the plastic liner is formed by a programmed temperature rising method. Preferably, the specific steps of the programmed temperature increase are: increasing the programmed temperature to a first temperature within a first time, maintaining the temperature at the first temperature for a second time, increasing the programmed temperature from the first temperature to a second temperature within a third time, and maintaining the temperature at the second temperature for a fourth time. The first temperature T1 satisfies the relationship t1≤T1≤t1+20, t1 is the viscosity starting temperature of the adhesive film, The second temperature T2 satisfies the relationship t2≤T2≤t3+20, t2 is the decomposition temperature of the adhesive layer, and t3 is the decomposition temperature of the adhesive film.

6. The molding process of the pressure vessel liner according to claim 5, characterized in that: The first time is 10 min-30 min, the second time is 5 min-15 min, the third time is 5 min-15 min, and the fourth time is 5 min-30 min; and / or, The temperature of the valve seat during the rotational molding process is 5°C-30°C higher than the program temperature of the rotational molding; and / or, The molding process further comprises a step of cooling the rotationally molded pressure container after programmed heating.

7. The molding process of the pressure vessel liner according to any one of claims 1 to 6, characterized in that: The decomposition temperature of the adhesive layer is greater than the bonding effective temperature of the adhesive film; and / or, The decomposition temperature of the adhesive layer is lower than the decomposition temperature of the adhesive film; and / or, The material of the adhesive film is selected from at least one of polyolefin, ethylene-vinyl acetate copolymer, and maleic anhydride grafted polyethylene; and / or, The material of the adhesive is selected from at least one of vinyltriethoxysilane, γ-chloropropyltrichlorosilane and chloromethyltriethoxysilane.

8. The molding process of the pressure vessel liner according to any one of claims 1 to 7, characterized in that: The thickness of the adhesive film is 0.02 mm-1 mm; and / or, The bonding effective temperature of the adhesive film is 99°C-230°C; and / or, The decomposition temperature of the adhesive layer is 155°C-230°C.

9. A pressure vessel liner, characterized in that: It is made by the molding process of the pressure vessel liner according to any one of claims 1 to 8.

10. A pressure vessel, characterized in that: The invention comprises the pressure vessel liner as claimed in claim 9.

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