A high barrier PVC coating film and preparation method thereof

Abstract

The present application discloses a high-barrier PVC coating film and a preparation method thereof, and belongs to the field of film material production. A high-barrier PVC coating film comprises a PVC film and a barrier coating disposed on the PVC film; the PVC film is subjected to plasma surface treatment and grafted with long-chain acrylate and hydroxy acrylate; the barrier coating is prepared from raw materials comprising the following parts by weight: 100 parts of PVA; 6 to 12 parts of formaldehyde; 10 to 15 parts of glycidyl ether containing two epoxy groups; and 0.1 to 1 part of a cross-linking accelerator. The present application has the advantages of improving the barrier properties and weather resistance of the PVC film.

Description

Technical Field

[0001] The present application relates to the field of film material production, and in particular to a high-barrier PVC coated film and a preparation method thereof. Background Art

[0002] PVC film, or polyvinyl chloride film, is widely used in building materials, packaging, furniture and medical fields. PVC film is a commonly used inflatable film material with good wear resistance, so it is often used in advertising balloons and children's amusement facilities. PVC film also has good flexibility and weighing properties, so PVC film can also be used in the fields of swimming rings and mattresses.

[0003] Due to the wide range of applications of PVC film, in addition to testing the wear resistance and flexibility of the film material, it is also necessary to test the barrier properties of the film material to determine whether the film material has sufficient durability to meet the needs of the application environment.

[0004] Generally, in an environment with little external interference, the barrier performance of PVC film meets the basic requirements. However, the weather resistance of PVC film is poor. It has great interference to the material in a more stringent application environment, which can easily have a negative impact on the barrier properties of PVC film, resulting in poor actual application effect of PVC film. Summary of the invention

[0005] In order to improve the barrier properties and weather resistance of PVC films, the present application provides a high-barrier PVC coating film and a preparation method thereof.

[0006] In the first aspect, the present application provides a high barrier PVC coating film adopting the following technical solution:

[0007] A high-barrier PVC coated film, comprising a PVC film and a barrier coating disposed on the PVC film;

[0008] The PVC film is subjected to plasma surface treatment and grafted with long-chain acrylate and hydroxy acrylate;

[0009] The barrier coating is prepared from the following raw materials in parts by weight:

[0010] PVA 100 copies;

[0011] 6-12 parts of formaldehyde;

[0012] 10-15 parts of glycidyl ether containing two epoxy groups;

[0013] Cross-linking accelerator 0.1 to 1 part.

[0014] By adopting the above technical scheme, after the PVC film is surface treated with plasma, the number of active groups on the film surface increases, the interfacial bonding ability with the barrier coating is enhanced, and the hydrophobicity of the film surface is modified by long-chain acrylates to improve the water-isolating ability of the PVC film interface. The reaction affinity characteristics of the film surface are modified by hydroxyl acrylates to further promote the improvement of the bonding ability and stability between the PVC film and the barrier coating.

[0015] PVA refers to polyvinyl alcohol. PVA can form a transparent coating with good barrier properties on the surface of PVC film. The selected glycidyl ether contains two epoxy groups. On the one hand, it can react with PVA to increase the cross-linking density of the PVA coating and improve the water barrier ability. On the other hand, it reacts with the hydroxy acrylate on the surface of the PVC film to enhance the bonding degree between the PVC film and the barrier coating, thereby improving weather resistance, adapting to harsh environmental changes, and being more durable. Since PVA contains more hydrophilic hydroxyl groups, formaldehyde is used to partially acetalize polyvinyl alcohol, reduce the proportion of hydroxyl groups, improve hydrophobicity, and thus improve water barrier performance.

[0016] Optionally, the glycidyl ether containing two epoxy groups is selected from one or more of diglycidyl ether, ethylene glycol diglycidyl ether and 1,2-cyclohexanediol diglycidyl ether.

[0017] By adopting the above technical scheme, the above-mentioned glycidyl ether containing two epoxy groups can form a cross-linked network structure with the acetalized polyvinyl alcohol, and the degree of cross-linking is moderate, so as to obtain high barrier capacity. If the glycidyl ether contains three or more epoxy groups, the brittleness of the coating increases and the flexibility of the PVC coating film decreases. Therefore, the selection of the above-mentioned glycidyl ether containing two epoxy groups can meet the balance between mechanical properties and barrier properties.

[0018] Optionally, the glycidyl ether containing two epoxy groups is prepared by compounding ethylene glycol diglycidyl ether and 1,2-cyclohexanediol diglycidyl ether in a weight ratio of 1:(0.25-0.33).

[0019] By adopting the above technical scheme, the di-methylene group of ethylene glycol diglycidyl ether provides toughness, and the hexa-membered ring of 1,2-cyclohexanediol diglycidyl ether provides rigidity, thereby achieving a good combination of toughness and rigidity and further improving the weather resistance of the PVC coating film.

[0020] Optionally, the cross-linking accelerator is one or both of triethanolamine and N-methyldiethanolamine.

[0021] Optionally, the degree of polymerization of the PVA is 1200-1700.

[0022] By adopting the above technical solution, PVA with a moderate degree of polymerization is selected, the adhesion ability and uniformity of the barrier coating are balanced, and a PVC coating film with better barrier ability is obtained.

[0023] Optionally, the long-chain acrylic ester is selected from one or both of lauryl methacrylate and lauryl acrylate.

[0024] By adopting the above technical scheme, lauryl methacrylate and lauryl acrylate contain continuous twelve-carbon carbon chains, which effectively modify the hydrophobicity of the film surface, improve the water-isolating ability of the PVC film interface, and balance the effect of the long-chain carbon structure on the adhesion of the barrier coating, thereby ensuring the stable combination of the barrier coating and the PVC film.

[0025] Optionally, the hydroxyacrylate is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.

[0026] By adopting the above technical scheme, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate can be grafted with hydroxyl groups on the surface of the PVC film, thereby improving the surface activity of the PVC film and providing reaction and combination for the glycidyl ether in the barrier coating.

[0027] Optionally, the formaldehyde is provided by a formaldehyde solution with a concentration of 30 to 35 wt%.

[0028] In the second aspect, the present application provides a method for preparing a high barrier PVC coating film using the following technical solution:

[0029] A method for preparing a high barrier PVC coating film comprises the following steps:

[0030] The PVC film is subjected to plasma surface treatment, and then immersed in a grafting solution, wherein the grafting solution is an alcohol aqueous solution containing long-chain acrylate and hydroxy acrylate, and after the immersion is completed, the film is taken out, washed, dried, and set aside;

[0031] PVA is dissolved in water, heated to 70-85°C, the pH is adjusted to 4-5, a formaldehyde solution is added and reacted for 2-3 hours, and the pH is neutralized to neutral after the reaction to obtain an acetalized polyvinyl alcohol solution, and a glycidyl ether containing two epoxy groups and a cross-linking accelerator are added to the acetalized polyvinyl alcohol solution, and the barrier coating is obtained after stirring evenly;

[0032] The barrier coating is coated on a PVC film and dried at 80-90° C. to form a barrier coating and obtain a high-barrier PVC coating film.

[0033] By adopting the above technical solution, polyvinyl alcohol is first partially polycondensed to form a preliminary cross-linked structure, while improving the water barrier ability of polyvinyl alcohol, and then further cross-linked with glycidyl ether containing two epoxy groups to form a three-dimensional structural coating. The coating has a strong bonding ability with the PVC film and good weather resistance.

[0034] Optionally, the concentration of the long-chain acrylate in the grafting solution is 10-15 wt %, and the concentration of the hydroxy acrylate in the grafting solution is 5-10 wt %.

[0035] Optionally, when the PVC film is immersed in the grafting solution, the temperature of the grafting solution is 60-70°C.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. After the PVC film is treated with plasma, the number of active groups on the film surface increases, and the interfacial bonding ability with the barrier coating is enhanced. PVA can form a transparent coating with good barrier properties on the surface of the PVC film. The selected glycidyl ether contains two epoxy groups. On the one hand, it can react with the hydroxyl group of PVA to increase the cross-linking density of the PVA coating and improve the water barrier ability. On the other hand, it reacts with the hydroxyl acrylate on the surface of the PVC film to enhance the bonding degree between the PVC film and the barrier coating, thereby improving weather resistance, adapting to harsh environmental changes, and being more durable.

[0038] 2. After the PVC film is treated with plasma surface, long-chain acrylate and hydroxy acrylate are grafted. The long-chain acrylate modifies the hydrophobicity of the film surface and improves the water barrier ability of the PVC film interface. The reaction affinity characteristics of the hydroxy acrylate modified film surface further promote the improvement of the bonding ability and stability of the PVC film and the barrier coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a planar structural diagram of the PVC coating film in Example 1.

[0040] Description of reference numerals:

[0041] 1. PVC film; 2. Barrier coating. DETAILED DESCRIPTION

[0042] The following is combined with Figure 1 This application is described in further detail.

[0043] Example 1

[0044] A high barrier PVC coating film comprises a PVC film 1 and a barrier coating 2. The barrier coating 2 can be arranged on one side or both sides of the PVC film 1 as required. In this embodiment, the barrier coating 2 is specifically arranged on one side of the PVC film 1. Figure 1shown.

[0045] A method for preparing a high barrier PVC coating film comprises the following steps:

[0046] PVC membrane pretreatment:

[0047] The PVC film with a thickness of 80 μm was subjected to atmospheric pressure plasma surface treatment. The power of the plasma equipment was 2000 W. The PVC film was then immersed in the grafting solution. The temperature of the grafting solution was 60°C and the immersion time was 1.5 h. After the immersion, the PVC film was taken out, repeatedly washed with water and ethanol, and dried for use.

[0048] The grafting solution uses 70 wt % ethanol aqueous solution as solvent, and contains 10 wt % lauryl methacrylate and 5 wt % hydroxyethyl acrylate.

[0049] Barrier coating preparation:

[0050] Weigh 1000 g of PVA with a polymerization degree of 1200, 170 g of a formaldehyde solution with a concentration of 35 wt%, 100 g of ethylene glycol diglycidyl ether, and 1 g of N-methyldiethanolamine.

[0051] PVA was dissolved in 8L water, heated to 70°C, hydrochloric acid was added to adjust the pH to 4, formaldehyde solution was added and reacted for 3h, after the reaction, ammonia water was added to adjust the pH to 7 to obtain acetalized polyvinyl alcohol solution, ethylene glycol diglycidyl ether and N-methyldiethanolamine were added to the acetalized polyvinyl alcohol solution, and the barrier coating was obtained after stirring evenly.

[0052] Coating film preparation:

[0053] The barrier coating was coated on the PVC film and dried at 80° C. to form a barrier coating with a thickness of 5 μm, thereby obtaining a high-barrier PVC coating film.

[0054] Example 2

[0055] The difference between this embodiment and embodiment 1 is that the preparation method of the high barrier PVC coating film is different.

[0056] A method for preparing a high barrier PVC coating film comprises the following steps:

[0057] PVC membrane pretreatment:

[0058] The PVC film with a thickness of 80 μm was subjected to atmospheric pressure plasma surface treatment. The power of the plasma equipment was 2000 W. The PVC film was then immersed in the grafting solution. The temperature of the grafting solution was 70°C and the immersion time was 1.5 h. After the immersion, the PVC film was taken out, repeatedly washed with water and ethanol, and dried for use.

[0059] The grafting solution uses 70 wt % ethanol aqueous solution as solvent, and contains 15 wt % lauryl methacrylate and 10 wt % hydroxyethyl acrylate.

[0060] Barrier coating preparation:

[0061] Weigh 1000 g of PVA with a polymerization degree of 1700, 40 g of a formaldehyde solution with a concentration of 30 wt%, 150 g of ethylene glycol diglycidyl ether, and 10 g of N-methyldiethanolamine.

[0062] PVA was dissolved in 8L water, heated to 85°C, hydrochloric acid was added to adjust the pH to 5, formaldehyde solution was added and reacted for 2h, after the reaction, ammonia water was added to adjust the pH to 7 to obtain acetalized polyvinyl alcohol solution, ethylene glycol diglycidyl ether and N-methyldiethanolamine were added to the acetalized polyvinyl alcohol solution, and the barrier coating was obtained after stirring evenly.

[0063] Coating film preparation:

[0064] The barrier coating was coated on the PVC film and dried at 90° C. to form a barrier coating with a thickness of 5 μm, thereby obtaining a high-barrier PVC coating film.

[0065] Example 3

[0066] The difference between this embodiment and embodiment 1 is that the preparation method of the high barrier PVC coating film is different, specifically, the preparation method of the barrier coating is different.

[0067] An equal amount of 1,2-cyclohexanediol diglycidyl ether was used to replace ethylene glycol diglycidyl ether, that is, the amount of ethylene glycol diglycidyl ether added was 0 g, and the amount of 1,2-cyclohexanediol diglycidyl ether added was 100 g.

[0068] Example 4

[0069] The difference between this embodiment and embodiment 1 is that the preparation method of the high barrier PVC coating film is different, specifically, the preparation method of the barrier coating is different.

[0070] Part of the ethylene glycol diglycidyl ether was replaced by 1,2-cyclohexanediol diglycidyl ether, so that the added amount of ethylene glycol diglycidyl ether was 80 g and the added amount of 1,2-cyclohexanediol diglycidyl ether was 20 g.

[0071] Example 5

[0072] The difference between this embodiment and embodiment 1 is that the preparation method of the high barrier PVC coating film is different, specifically, the preparation method of the barrier coating is different.

[0073] Part of the ethylene glycol diglycidyl ether was replaced by 1,2-cyclohexanediol diglycidyl ether, so that the added amount of ethylene glycol diglycidyl ether was 75 g and the added amount of 1,2-cyclohexanediol diglycidyl ether was 25 g.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is that the preparation method of the high barrier PVC coating film is different, specifically, the preparation method of the barrier coating is different.

[0076] Barrier coating preparation:

[0077] Weigh 1000 g of PVA with a degree of polymerization of 1200, 100 g of ethylene glycol diglycidyl ether, and 1 g of N-methyldiethanolamine.

[0078] PVA was dissolved in 8 L of water, ethylene glycol diglycidyl ether and N-methyldiethanolamine were added, and the mixture was stirred evenly to obtain a barrier coating.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 1 is that the preparation method of the high barrier PVC coating film is different, specifically, the preparation method of the barrier coating is different.

[0081] Barrier coating preparation:

[0082] Weigh 1000 g of PVA with a polymerization degree of 1200, 170 g of a formaldehyde solution with a concentration of 35 wt %, 100 g of glycidyl methacrylate, and 1 g of N-methyldiethanolamine.

[0083] PVA was dissolved in 8L of water, heated to 70°C, hydrochloric acid was added to adjust the pH to 4, formaldehyde solution was added and reacted for 3h, after the reaction, ammonia water was added to adjust the pH to 7 to obtain acetalized polyvinyl alcohol solution, glycidyl methacrylate and N-methyldiethanolamine were added to the acetalized polyvinyl alcohol solution, and the barrier coating was obtained after stirring evenly.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 1 is that the preparation method of the high barrier PVC coating film is different, specifically, the pretreatment of the PVC film is different.

[0086] PVC membrane pretreatment:

[0087] The PVC film with a thickness of 80 μm was subjected to atmospheric pressure plasma surface treatment. The power of the plasma equipment was 2000 W. The PVC film was then immersed in the grafting solution. The temperature of the grafting solution was 60°C and the immersion time was 1.5 h. After the immersion, the PVC film was taken out, repeatedly washed with water and ethanol, and dried for use.

[0088] The grafting solution uses 70 wt % ethanol aqueous solution as solvent, and the grafting solution contains 10 wt % lauryl methacrylate.

[0089] Comparative Example 4

[0090] The difference between this comparative example and Example 1 is that the preparation method of the high barrier PVC coating film is different, specifically, the pretreatment of the PVC film is different.

[0091] PVC membrane pretreatment:

[0092] The PVC film with a thickness of 80 μm was subjected to atmospheric pressure plasma surface treatment. The power of the plasma equipment was 2000 W. The PVC film was then immersed in the grafting solution. The temperature of the grafting solution was 60°C and the immersion time was 1.5 h. After the immersion, the PVC film was taken out, repeatedly washed with water and ethanol, and dried for use.

[0093] The grafting solution uses 70 wt % ethanol aqueous solution as solvent, and the grafting solution contains 5 wt % hydroxyethyl acrylate.

[0094] Coating film performance test

[0095] The PVC coated films prepared in Examples 1-5 and Comparative Examples 1-4 were taken as samples, and an untreated PVC film was taken as a blank sample to carry out the following tests.

[0096] Oxygen permeation test: refer to GB / T 1038-2000 "Plastic film and sheet gas permeability test", test the oxygen permeation of different samples, the results are shown in Table 1.

[0097] Water vapor transmission rate test: refer to GB / T 21529-2008 "Determination of water vapor transmission rate of plastic films and sheets", test the oxygen transmission rate of different samples, the results are shown in Table 1.

[0098] High temperature and high humidity tolerance test: different samples were placed in a constant temperature and humidity test chamber for aging for 100 hours, with a temperature of 75±2°C and a humidity of 85±2%. After aging, the samples were taken out of the constant temperature and humidity test chamber, dried and placed at room temperature for 24 hours before oxygen permeability test and water vapor permeability test. The results are shown in Table 2.

[0099] Salt spray tolerance test: different samples were placed in a salt spray test machine for aging for 48 hours, with a temperature of 25±2°C, a humidity of 85±2%, and a sodium chloride solution mass concentration of 5±1%. After aging, the samples were taken out from the constant temperature and humidity test chamber, dried and placed at room temperature for 24 hours, and then oxygen permeability test and water vapor permeability test were performed. The results are shown in Table 2.

[0100] Table 1

[0101]

[0102] Table 2

[0103]

[0104]

[0105] Combining the analysis of Table 1 and Table 2, it can be seen that the uncoated PVC film is poor in oxygen barrier properties, and after high temperature and humidity or salt spray aging, the PVC film has a serious decline in water vapor barrier properties. In comparison, the PVC coated film prepared by coating the barrier coating in Example 1 has greatly improved oxygen barrier properties and water vapor barrier properties, and after high temperature and humidity or salt spray aging, the decline in barrier properties is small, and still maintains a good prospect for use.

[0106] From the analysis of Example 1 combined with Comparative Examples 1-2, it can be seen that the barrier coating uses PVA as the coating theme, which is partially acetalized with formaldehyde and cross-linked with glycidyl ether containing two epoxy groups, thereby promoting the combination of the barrier coating and the pretreated PVC film and improving the weather resistance of the PVC coating film.

[0107] Combining the analysis of Example 1 with Comparative Examples 3-4, it can be seen that after pretreatment, the PVC film is grafted with long-chain acrylates and hydroxy acrylates to improve the surface activity of the PVC film and provide a basis for combining with the barrier coating, thereby further improving the barrier properties of the PVC coated film.

[0108] By analyzing Example 1 in combination with Examples 3-5, it can be seen that the glycidyl ether containing two epoxy groups in the barrier coating is compounded with ethylene glycol diglycidyl ether and 1,2-cyclohexanediol diglycidyl ether, and the high temperature and high humidity tolerance of the PVC coating film is further improved by improving the cross-linking structure.

[0109] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high barrier PVC coating film, characterized in that: It comprises a PVC film and a barrier coating disposed on the PVC film; The PVC film is subjected to plasma surface treatment and grafted with long-chain acrylate and hydroxy acrylate; The barrier coating is prepared from the following raw materials in parts by weight: PVA 100 copies; Formaldehyde 6~12 parts; 10-15 parts of glycidyl ether containing two epoxy groups; Cross-linking accelerator 0.1~1 part; Preparation method of the barrier coating: PVA is dissolved in water, heated to 70-85°C, the pH is adjusted to 4-5, formaldehyde solution is added and reacted for 2-3 hours, and the pH is neutralized to neutral after the reaction to obtain an acetalized polyvinyl alcohol solution, and a glycidyl ether containing two epoxy groups and a cross-linking accelerator are added to the acetalized polyvinyl alcohol solution, and the barrier coating is obtained after stirring evenly; The barrier coating is applied to a PVC film and dried at 80-90° C. to form a barrier coating.

2. The high barrier PVC coating film according to claim 1, characterized in that: The glycidyl ether containing two epoxy groups is selected from one or more of diglycidyl ether, ethylene glycol diglycidyl ether and 1,2-cyclohexanediol diglycidyl ether.

3. The high barrier PVC coating film according to claim 1, characterized in that: The glycidyl ether containing two epoxy groups is prepared by compounding ethylene glycol diglycidyl ether and 1,2-cyclohexanediol diglycidyl ether in a weight ratio of 1:(0.25-0.33).

4. The high barrier PVC coating film according to claim 1, characterized in that: The degree of polymerization of the PVA is 1200-1700.

5. The high barrier PVC coating film according to claim 1, characterized in that: The long-chain acrylic acid ester is selected from one or both of lauryl methacrylate and lauryl acrylate.

6. The high barrier PVC coating film according to claim 1, characterized in that: The hydroxy acrylate is selected from one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.

7. The high barrier PVC coating film according to claim 1, characterized in that: The formaldehyde is provided by a formaldehyde solution with a concentration of 30-35wt%.

8. A method for preparing a high barrier PVC coating film according to any one of claims 1 to 7, characterized in that: The following steps are involved: The PVC film is subjected to plasma surface treatment, and then immersed in a grafting solution, wherein the grafting solution is an alcohol aqueous solution containing long-chain acrylate and hydroxy acrylate, and after the immersion is completed, the film is taken out, washed, dried, and set aside; The barrier coating is applied to the PVC film and dried at 80-90°C to form a barrier coating to obtain a high-barrier PVC coating film.

9. The method for preparing a high barrier PVC coating film according to claim 8, characterized in that: The concentration of the long-chain acrylate in the grafting solution is 10-15 wt %, and the concentration of the hydroxy acrylate in the grafting solution is 5-10 wt %.

10. The method for preparing a high barrier PVC coating film according to claim 8, characterized in that: When the PVC film is immersed in the grafting solution, the temperature of the grafting solution is 60-70°C.

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