PVA composite film for air bag and method for preparing the same

Abstract

The application relates to the technical field of high polymer materials, in particular to a PVA composite film for an air bag and a preparation method thereof, wherein the PVA composite film is prepared from the following raw materials in parts by weight: 90-110 parts of PVA, 1-2.5 parts of ethyl p-hydroxycinnamate, 3-5 parts of vinylphenyl silicone oil, 5-8 parts of end-side double hydrogen-containing silicone oil, 0.0008-0.0012 parts of a platinum catalyst, 4-7 parts of a crosslinking agent, 16-22 parts of a plasticizer and 0.1-1 parts of a heat stabilizer; the PVA composite film has the advantages that the processing temperature of the PVA material can be reduced, and the heat resistance and the mechanical properties of the PVA are simultaneously improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of high polymer materials, in particular to a PVA composite film for an inflatable bag and a preparation method thereof. BACKGROUND

[0002] The inflatable bag is a packaging material, which is generally made of high polymer material and filled with gas. The inflatable bag is light and easy to carry, and can be used in the fields of packaging, buffering and transportation. The inflatable bag made of polyvinyl alcohol (PVA) has the advantages of biodegradability, wide source, high strength, high light transmittance, antistatic property and oil resistance, so that the PVA inflatable bag is widely used.

[0003] However, due to the regular molecular structure and high crystallinity of PVA, a large number of hydroxyl groups and strong hydrogen bonds formed therebetween result in a high melting point of PVA. The melting point of PVA with an alcoholysis degree of 98% ranges from 220 to 240 DEG C, and PVA starts to dehydrate and etherize at about 170 DEG C, a large number of crosslinking points are generated, and then the PVA is discolored and degraded, resulting in insufficient mechanical properties. In the related art, for example, the preparation method of the PVA film disclosed in CN109608797B, a borosilicon resin is prepared as a crosslinking agent to improve the heat resistance of PVA, so that the degradation rate of PVA is greatly reduced when the PVA is melt-extruded at high temperature. However, the borosilicon resin is generated by hydrolysis and condensation of alkane silane coupling agent, aromatic silane coupling agent and boron element, and there are great difficulties in actual preparation. Therefore, there are still great challenges in the preparation of PVA film. SUMMARY

[0004] In order to reduce the processing temperature of PVA material and improve the heat resistance and mechanical properties of PVA, the application provides a PVA composite film for an inflatable bag and a preparation method thereof.

[0005] In a first aspect, the application provides a PVA composite film for an inflatable bag, which adopts the following technical scheme:

[0006] The PVA composite film for the inflatable bag comprises the following raw materials by weight: PVA 90-110 parts, ethyl p-hydroxycinnamate 1-2.5 parts, vinylphenyl silicone oil 3-5 parts, end-side double hydrogen-containing silicone oil 5-8 parts, platinum catalyst 0.0008-0.0012 parts, crosslinking agent 4-7 parts, plasticizer 16-22 parts and heat stabilizer 0.1-1 parts.

[0007] By adopting the technical scheme, the application can improve the mechanical strength of the PVA composite film, such as tensile strength and elongation at break, by adding end-side double hydrogen-containing silicone oil, vinyl phenyl silicone oil and ethyl p-hydroxycinnamate in the PVA composite film system, and by the catalysis of platinum catalyst, the silicon hydrogen addition cross-linking reaction occurs, and a three-dimensional cross-linking structure is formed in the PVA composite film system. The application selects to add ethyl p-hydroxycinnamate, which contains unsaturated double bonds and hydroxyl groups, ester groups and benzene rings, and after the reaction with the end-side double hydrogen-containing silicone oil, the hydroxyl groups and ester groups contained in the ethyl p-hydroxycinnamate can form hydrogen bonds with the hydroxyl groups contained in the PVA molecular chain, thereby improving the compatibility of the silicon hydrogen addition polymer and the PVA molecular chain, and the end-side double hydrogen-containing silicone oil can also react with the vinyl phenyl silicone oil, and the polymer molecules after the reaction contain a large number of benzene rings, which can be inserted between the PVA molecules to produce steric hindrance to the PVA molecular chain, thereby greatly reducing the hydrogen bonds between the molecular chains, so that the processing temperature of the PVA composite film can be reduced, and the large number of benzene ring structures contained in the silicon hydrogen addition product and the high temperature resistance of the silicon polymer itself can greatly improve the heat resistance of the PVA composite film. The selection of the end-side double hydrogen-containing silicone oil can also increase the reaction sites. In summary, the application introduces a three-dimensional cross-linking structure in the PVA composite film system through the silicon hydrogen addition reaction, so that the mechanical properties, heat resistance and processing temperature of the PVA composite film are obviously improved.

[0008] As a preferred, the addition amount of the ethyl p-hydroxycinnamate is 1.5 parts by weight.

[0009] By adopting the above technical scheme, since the molecular weight of the ethyl p-hydroxycinnamate is small, its reactivity in the system is less than that of the vinyl phenyl silicone oil, and if the addition amount is too large, the end-side double hydrogen-containing silicone oil will be completely reacted, so that the vinyl phenyl silicone oil is difficult to react with the end-side double hydrogen-containing silicone oil due to the large molecular chain and steric hindrance, so that the benzene ring structure of the silicon hydrogen addition product is less; the vinyl phenyl silicone oil has limited molecular chain extension due to the reduction of hydrogen bond interaction with the PVA molecular chain, so that the steric hindrance of the benzene ring structure to the hydrogen bond is reduced, so that the overall performance of the PVA composite film is reduced; therefore, the addition amount of the ethyl p-hydroxycinnamate is 1.5 parts by weight, which is a more preferred choice.

[0010] As a preferred, the PVA composite film further comprises 0.001-1.5 parts by weight of nano-montmorillonite powder.

[0011] By adopting the above technical scheme, the nano-montmorillonite powder can be used as a reinforcing material to improve the tensile strength of the PVA composite film, and the lamellar structure can hinder the expansion of micro-cracks, so that the tensile strength is improved; but the interfacial tension between the nano-montmorillonite powder and the system reduces the toughness of the PVA composite film.

[0012] Preferably, the nanometer montmorillonite powder is a modified nanometer montmorillonite powder, which is obtained by modifying the surface of the nanometer montmorillonite powder with a silane coupling agent.

[0013] By using the above technical solution, the surface of the nanometer montmorillonite is modified with a silane coupling agent, which can improve the compatibility between the nanometer montmorillonite and the system, thereby improving the strength of the PVA composite film while improving the toughness of the PVA composite film.

[0014] Preferably, the silane coupling agent is an unsaturated silane coupling agent.

[0015] By using the above technical solution, the unsaturated silane coupling agent can participate in the silicon-hydrogen cross-linking reaction, making it a cross-linking node, further strengthening the three-dimensional cross-linked network system, making the PVA composite film more integrated, and the selected montmorillonite powder as a nanometer material can also hinder the hydrogen bonds between the molecular chains, thereby further optimizing the performance of the PVA composite film.

[0016] Preferably, the unsaturated silane coupling agent is one or more of vinyl tributylketoxime silane, 7-octenyl trimethoxysilane, vinyl triethoxysilane, acryloyloxy methyl trimethoxysilane, and vinyl triisopropoxysilane.

[0017] By using the above technical solution, although not all of the unsaturated silane coupling agents are explored in the embodiments of the present application, in theory, these unsaturated silane coupling agents can achieve similar technical effects as the embodiments of the present application, and therefore, they are within the protection scope of the present application.

[0018] Preferably, the particle size of the nanometer montmorillonite powder is 30-100 nm.

[0019] By using the above technical solution, a paste with a smaller particle size results in higher production costs and insufficient dispersibility, and a particle size within this range is more suitable for actual production.

[0020] In a second aspect, the present application provides a preparation method of a PVA composite film for an inflatable bag, which adopts the following technical solution:

[0021] A preparation method of a PVA composite film for an inflatable bag, which comprises the following steps:

[0022] Each raw material is put into a high-speed mixer for sufficient mixing to obtain a mixture, and then the mixture is added into a single-screw extruder for melt extrusion, the extrusion temperature is 160-165℃, and the mixture is granulated, and then the granulated mixture is aged in a sealed space, the aging temperature is 80-110℃; then the aged granules are extruded and blown into a film by a double-screw extruder, the extrusion temperature is 160-165℃, and a PVA composite film for an inflatable bag is prepared.

[0023] By adopting the technical scheme, the raw material and raw material ratio of the PVA composite film are selected to have a stable processing temperature, and the processing temperature of the PVA composite film is kept below the decomposition temperature, thereby improving the processing stability.

[0024] In summary, the present application has at least one of the following beneficial technical effects:

[0025] 1. The present application adds end-side double hydrogen-containing silicone oil, vinyl phenyl silicone oil and ethyl p-hydroxycinnamate in the PVA composite film system, and a silicon hydrogen addition cross-linking reaction occurs under the catalysis of platinum catalyst, forming a three-dimensional cross-linked structure in the PVA composite film system, which can improve the mechanical strength of the PVA composite film, such as tensile strength, elongation at break, etc. Ethyl p-hydroxycinnamate contains unsaturated double bonds and hydroxyl, ester and benzene rings, etc. After reaction with end-side double hydrogen-containing silicone oil, the compatibility of the silicon hydrogen addition polymer and the PVA molecular chain can be improved, and the end-side double hydrogen-containing silicone oil can also react with the vinyl phenyl silicone oil. The polymer molecules after the reaction contain a large number of benzene rings, which can be inserted between the PVA molecules, and the hydrogen bonds between the molecular chains are greatly reduced, thereby reducing the processing temperature of the PVA composite film. The silicon hydrogen addition product contains a large number of benzene ring structures, and the silicon polymer itself has high temperature resistance, so the heat resistance of the PVA composite film is greatly improved.

[0026] 2. The PVA composite film prepared by the present application has a low processing temperature and can be extruded and blown at 160℃ by a double screw extruder. The tensile strength of the prepared PVA composite film is in the range of 78-94MPa, the elongation at break is in the range of 403-458%, the thermal weight loss 10% temperature is higher than 303℃, and the highest can reach 360℃. It shows that the PVA composite film prepared by the present application has excellent mechanical properties and heat resistance. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below in combination with specific contents.

[0028] Raw materials

[0029] The raw materials in the embodiments of the application are all ordinary commercially available products; wherein, the PVA is PVA-1799, the alcoholysis degree is 99%, the polymerization degree is 1700, and is purchased from Anhui Wanwei New Material Co., Ltd.; the purity of ethyl p-hydroxycinnamate is 99%, and is an industrial grade with the brand of Ruiya; the platinum catalyst is Karstedt catalyst; the vinyl phenyl silicone oil is end-vinyl phenyl silicone oil, the phenyl content is 8%, the viscosity is 200 cst, and is purchased from Liansheng Xinghuo Organic Silicon (Jiangxi) Co., Ltd., the model is BH-SV206; the end-side double hydrogen-containing silicone oil is purchased from Foshan Shangjincheng New Material Technology Co., Ltd., the model is SJ-HSH-25, and the hydrogen content is 0.25 wt%; the crosslinking agent is DuPont 371 PVA crosslinking agent; the plasticizer is glycerol; the thermal stabilizer is sodium hydroxide; and the nano montmorillonite powder is purchased from Tobi New Material (Guangzhou) Co., Ltd.

[0030] Embodiment

[0031] Embodiment 1

[0032] A PVA composite film for an inflatable bag, the raw materials and the amounts of the raw materials are shown in Table 1, and the preparation method is as follows:

[0033] The raw materials are put into a high-speed mixer for sufficient mixing to obtain a mixture, and then the mixture is added into a single-screw extruder for melt extrusion, the extrusion temperature is 165℃, and the mixture is granulated, and then the granulated mixture is aged in a closed space for 24h, the aging temperature is 100℃; then the aged granules are extruded by a double-screw extruder to blow a film, the extrusion temperature is 160℃, and the PVA composite film for an inflatable bag is prepared, and the thickness of the PVA composite film is 15μm.

[0034] Table 1: Raw materials and amounts of the raw materials (kg) in Embodiment 1

[0035] PVA 100 ethyl p-hydroxycinnamate 1.5 vinylphenyl silicone oil 4 end-capped dihydrogen-containing silicone oil 6 platinum catalyst 0.001 crosslinking agent 5 plasticizer 20 heat stabilizer 0.5

[0036] Embodiment 2

[0037] A PVA composite film for an inflatable bag, which is different from Embodiment 1 in that the addition amount of ethyl p-hydroxycinnamate is 2.5kg, and the other steps are the same as those in Embodiment 1.

[0038] Embodiment 3

[0039] A PVA composite film for an inflatable bag, which is different from Embodiment 1 in that the raw materials further include 0.5kg of nano montmorillonite powder, the average particle size of which is 50nm, and the other steps are the same as those in Embodiment 1.

[0040] Embodiment 4

[0041] A PVA composite film for an air bag, which is different from Example 3 in that the added nano-montmorillonite powder is replaced by an equal amount of modified nano-montmorillonite powder, and the preparation method of the modified nano-montmorillonite powder is as follows:

[0042] A 100 mL ethanol aqueous solution with a volume ratio of 1:1 is prepared, then 0.1 g of methyltrimethoxysilane is added, stirred until dissolved, heated to 80℃, then 1 g of nano-montmorillonite powder is added, ultrasonically dispersed for 10 min, then continue to stir for 24 h, filter, dry, and obtain the modified nano-montmorillonite powder.

[0043] Example 5

[0044] A PVA composite film for an air bag, which is different from Example 3 in that the silane coupling agent used in the preparation of the modified nano-montmorillonite powder is an equal amount of unsaturated silane coupling agent, and the unsaturated silane coupling agent is 7-octenyltrimethoxysilane, and the remaining steps are the same as those of Example 3.

[0045] Example 6

[0046] A PVA composite film for an air bag, which is different from Example 5 in that the amount of added modified nano-montmorillonite powder is 1.5 kg, and the remaining steps are the same as those of Example 5.

[0047] Comparative Example

[0048] Comparative Example 1

[0049] A PVA composite film for an air bag, which is different from Example 1 in that the vinyl phenyl silicone oil is replaced by an equal amount of double-end vinyl silicone oil, and the double-end vinyl silicone oil is double-vinyl terminated polydimethylsiloxane with a viscosity of 200 cst, purchased from Shenzhen Jipeng Silicone Fluorine Material Co., Ltd., and the remaining steps are the same as those of Example 1.

[0050] Performance detection test

[0051] Detection method / test method

[0052] A PVA composite film for an air bag is prepared according to the preparation methods of Examples 1-6 and Comparative Example 1, respectively, and then detected according to the following detection methods, and the detection results are shown in Table 2.

[0053] Tensile strength and elongation at break: detected according to the detection method in GB / T1040-92 "Plastics - Determination of tensile properties";

[0054] Thermal stability: the temperature at which the sample loses 10% of its weight is tested using a Perkin-Elmer TGA-7 instrument; test conditions: heating rate 10℃ / min, temperature range 40℃-800℃, nitrogen atmosphere.

[0055] Table 2 Test results of Examples 1-6 and Comparative Example 1

[0056]

[0057]

[0058] From the test data of Examples 1-6 and Comparative Example 1, and Table 1, it can be seen that the PVA composite film prepared in the application has a lower processing temperature, which can be extruded by a twin-screw extruder at 160°C to blow film, and the tensile strength of the PVA composite film prepared is in the range of 78-94 MPa, the elongation at break is between 403-458%, and the 10% weight loss temperature is higher than 303°C, and can be as high as 360°C; it shows that the PVA composite film prepared in the application has excellent mechanical properties and heat resistance.

[0059] As can be seen from the test data of Example 1 and Comparative Example 1, by adding end-side double hydrogen-containing silicone oil, vinyl phenyl silicone oil and ethyl p-hydroxycinnamate in the PVA composite film system, the silicon-hydrogen addition cross-linking reaction occurs under the catalysis of platinum catalyst, the three-dimensional cross-linking structure is formed in the PVA composite film system, the mechanical strength of the PVA composite film can be improved, such as tensile strength, elongation at break and the like; the present application selects to add ethyl p-hydroxycinnamate, which contains unsaturated double bond and hydroxyl group, ester group and benzene ring and the like, after the reaction with end-side double hydrogen-containing silicone oil, the hydroxyl group and ester group contained therein can form hydrogen bond with the hydroxyl group contained in the PVA molecular chain, the compatibility of the silicon-hydrogen addition polymer with the PVA molecular chain is improved, and the end-side double hydrogen-containing silicone oil can also occur silicon-hydrogen addition reaction with the vinyl phenyl silicone oil, the polymer molecule after the reaction contains a large number of benzene rings, the benzene rings contained therein can be inserted between the PVA molecules, the hydrogen bond between the PVA molecular chains is greatly reduced, so that the processing temperature of the PVA composite film can be reduced, and the large amount of benzene ring structure contained in the silicon-hydrogen addition product and the high temperature resistance of the silicon polymer itself greatly improve the heat resistance of the PVA composite film; the selection of end-side double hydrogen-containing silicone oil can also increase the reaction site; in summary, the present application introduces three-dimensional cross-linking structure in the PVA composite film system through silicon-hydrogen addition reaction, the mechanical properties, heat resistance and processing temperature of the PVA composite film are obviously improved. According to Example 2, since the molecular weight of ethyl p-hydroxycinnamate is small, the reactivity in the system is less than that of vinyl phenyl silicone oil, the addition amount is too large, the end-side double hydrogen-containing silicone oil is completely reacted, and due to the large molecular chain of vinyl phenyl silicone oil, the reaction steric hindrance is large, it is difficult to react with end-side double hydrogen-containing silicone oil, so that the benzene ring structure of the silicon-hydrogen addition product is less; the molecular chain of vinyl phenyl silicone oil is limited due to the reduction of hydrogen bond with PVA molecular chain, the steric hindrance of benzene ring structure to hydrogen bond is reduced, so that the overall performance of the PVA composite film is reduced; therefore, the addition amount of ethyl p-hydroxycinnamate should not exceed 2.5 kg.

[0060] It can be seen from the test data of example 1 and examples 3-5 that the nanometer montmorillonite powder can be used as a reinforcing material to improve the tensile strength of the PVA composite film, and its lamellar structure can hinder the expansion of microcracks and also improve the tensile strength; but the interfacial tension between it and the system makes the toughness of the PVA composite film decrease to a certain extent. Surface modification of the nanometer montmorillonite by silane coupling agent can improve the compatibility between it and the system, thereby improving the strength of the PVA composite film while improving its toughness. The unsaturated silane coupling agent can participate in the silicon-hydrogen crosslinking reaction to make it a crosslinking node, further strengthen the three-dimensional crosslinking network system, make the PVA composite film more integrated, and the selected montmorillonite powder as a nanometer material can also hinder the hydrogen bonds between the molecular chains, thereby further optimizing the performance of the PVA composite film. In combination with example 6, if the modified nanometer montmorillonite powder is added too much, it is easy to cause the PVA composite film to have strong rigidity, therefore, the amount of its addition should not exceed 1.5 kg.

[0061] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. A method for preparing a PVA composite film for inflatable bags, characterized in that: The PVA composite film comprises the following raw materials in parts by weight: 90-110 parts PVA, 1-2.5 parts ethyl p-hydroxycinnamate, 3-5 parts vinylphenyl silicone oil, 5-8 parts end-side bihydrosilicone oil, 0.0008-0.0012 parts platinum catalyst, 4-7 parts crosslinking agent, 16-22 parts plasticizer, and 0.1-1 parts heat stabilizer; The preparation method of the PVA composite film includes the following steps: The raw materials for the PVA composite film are fed into a high-speed mixer and thoroughly mixed to obtain a mixture. The mixture is then added to a single-screw extruder for melt extrusion at a temperature of 160-165°C, followed by granulation. After granulation, the mixture is cured in a closed space at a temperature of 80-110°C. The cured granules are then extruded and blown into a film using a twin-screw extruder at a temperature of 160-165°C to obtain a PVA composite film for inflatable bags.

2. A PVA composite film for inflatable bags, characterized in that: The PVA composite film is prepared by the method for preparing a PVA composite film for an inflatable bag as described in claim 1.

3. The PVA composite film for inflatable bags according to claim 2, characterized in that: The amount of ethyl p-hydroxycinnamate added is 1.5 parts by weight.

4. The PVA composite film for inflatable bags according to claim 2, characterized in that: The raw materials for the PVA composite film also include 0.001-1.5 parts by weight of nano-montmorillonite powder.

5. The PVA composite film for inflatable bags according to claim 4, characterized in that: The nano-montmorillonite powder is a modified nano-montmorillonite powder, which is prepared by modifying the surface of nano-montmorillonite powder with a silane coupling agent.

6. The PVA composite film for inflatable bags according to claim 5, characterized in that: The silane coupling agent is an unsaturated silane coupling agent.

7. The PVA composite film for inflatable bags according to claim 6, characterized in that: The unsaturated silane coupling agent is one or more of vinyltributylone oxime silane, 7-octenyltrimethoxysilane, vinyltriethoxysilane, acryloyloxymethyltrimethoxysilane, and vinyltriisopropoxysilane.

8. The PVA composite film for inflatable bags according to claim 4, characterized in that: The particle size of the nano-montmorillonite powder is 30-100 nm.

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