High-barrier hot-melt adhesive film, preparation method therefor, and composite board

Abstract

The present invention relates to a high-barrier hot-melt adhesive film, a preparation method therefor, and a composite board. The hot-melt adhesive film comprises a first adhesive layer used for bonding with PVC, a second adhesive layer used for bonding with a metal, and a transition layer provided between the first adhesive layer and the second adhesive layer. Raw materials of the first adhesive layer comprise a copolyester and styrene-acrylonitrile-glycidyl methacrylate; and raw materials of the transition layer comprise nylon, maleic anhydride-grafted polyethylene and glass flakes. Redesigning the raw material formulas of the first adhesive layer and the transition layer of the hot-melt adhesive film in the present invention enables the hot-melt adhesive film to have better plasticizer barrier performance, and a better high-temperature peel strength and a peel strength retention rate under more severe thermal aging conditions. Thus, a composite board obtained by bonding a metal and PVC with the hot-melt adhesive film can be used in more severe working conditions, and is especially suitable for the requirement on peel strength under the condition of long-time use at perennially high outdoor temperatures, such as in equatorial areas.

Description

A high-barrier hot-melt adhesive film, a preparation method thereof, and a composite board Technical Field

[0001] The present invention belongs to the technical field of waterproof coiled materials, and in particular relates to a high-barrier hot-melt adhesive film, a preparation method thereof, and a composite board. Background Art

[0002] PVC waterproofing membranes are widely used in lightweight steel roofing systems due to their soft texture and excellent weldability. Traditionally, mechanical fixing and full-bonding methods have been used to attach PVC waterproofing membranes to metal roofs. However, these methods present challenges such as solvent evaporation and difficulty controlling the amount of adhesive applied.

[0003] Patent documents reveal that PVC waterproofing membranes and metal plates are hot-pressed together using hot-melt adhesive film to form PVC metal composite panels, which greatly saves the construction costs of light steel single-layer roof waterproofing systems and roof repair projects, improves construction quality, and shortens construction periods.

[0004] Chinese patent CN109207073A discloses a three-layer composite hot-melt adhesive film for bonding metals to polar functional plastics and its processing technology. The three-layer composite hot-melt adhesive film comprises an inner layer for bonding to the metal, an outer layer for bonding to the polar functional plastic, and a transition layer connecting the inner and outer layers. The outer layer, which bonds to the polar functional plastic, contains polar materials such as maleic anhydride-grafted polyethylene or a maleic anhydride-grafted polyethylene copolymer, a copolyester, and a tackifying resin. However, the grafting rate of maleic anhydride onto polyethylene or polyethylene copolymers is limited, limiting its ability to resist the large amounts of polar plasticizers found in polar substrates such as PVC.

[0005] Chinese patent CN114479682A discloses a hot-melt adhesive film for bonding metal to PVC and its preparation method. The first adhesive layer used for bonding to PVC utilizes a polyethylene-acrylate-maleic anhydride terpolymer and a maleic anhydride-grafted C5 / C9 copolymer resin. Leveraging the synergistic effect between the polyethylene-acrylate-maleic anhydride terpolymer and the maleic anhydride-grafted C5 / C9 copolymer resin, the first adhesive layer forms a strong barrier, preventing the migration of plasticizers from the PVC into the first adhesive layer, enhancing the hot-melt adhesive film's plasticizer resistance, and maintaining minimal peel strength degradation after long-term use. However, this still fails to meet the requirements for use in some harsh environments, such as in areas with high outdoor temperatures (e.g., areas with year-round high temperatures near the equator).

[0006] Summary of the Invention

[0007] Purpose of the invention: In order to solve the problems of the prior art, the present invention provides an improved hot melt adhesive film, which has better barrier properties to plasticizers, better high-temperature peel strength and more stringent peel strength retention after heat aging.

[0008] Technical solution: In order to solve the above technical problems, the present invention adopts the following technical solution:

[0009] A hot melt adhesive film for bonding metal to PVC, the hot melt adhesive film comprising a first adhesive layer for bonding to the PVC, a second adhesive layer for bonding to the metal, and a transition layer disposed between the first and second adhesive layers. The first adhesive layer comprises copolyester and styrene-acrylonitrile-glycidyl methacrylate, wherein the mass ratio of the copolyester to styrene-acrylonitrile-glycidyl methacrylate is 1:0.5-6.

[0010] The raw materials of the transition layer include nylon, maleic anhydride grafted polyethylene and glass flakes, and the mass ratio of the nylon, maleic anhydride grafted polyethylene and glass flakes is 1:0.3-3:0.2-3.

[0011] In some preferred embodiments, in the first adhesive layer, the mass ratio of the copolyester to styrene-acrylonitrile-glycidyl methacrylate is 1:0.6-2.5.

[0012] In some specific embodiments, the copolyester is a thermoplastic copolyetherester with a melt index of 10 to 20 g / 10 min (2.16 kg / 160° C.), such as ES-5 (melt index of 15 g / 10 min) produced by Nantong Xinxin Hot Melt Adhesive Co., Ltd.

[0013] In some embodiments, the raw material of the first adhesive layer further includes a high temperature resistant plasticizer, and the mass ratio of the copolyester to the high temperature resistant plasticizer is 1:0.01-4.

[0014] In some specific embodiments, the high temperature resistant plasticizer is an ester of trimellitic anhydride and a monohydric alcohol; and / or, the mass ratio of the copolyester to the high temperature resistant plasticizer is 1:0.2-1.5.

[0015] In some specific embodiments, the raw material of the first adhesive layer further includes an auxiliary agent, which includes one or a combination of antioxidants and ultraviolet absorbers. The mass ratio of the copolyester to the auxiliary agent is 1:0.01-0.3.

[0016] In some preferred embodiments, the mass ratio of the nylon, maleic anhydride grafted polyethylene and glass flakes is 1:0.5-1.5:0.5-1.5.

[0017] In some specific embodiments, the crystallinity of the nylon is greater than 62%, and the crystallinity is tested by X-ray diffraction.

[0018] In some specific embodiments, the particle size of the glass flakes is 70 to 130 meshes. Preferably, the particle size of the glass flakes is 70 to 90 meshes.

[0019] In some specific embodiments, the raw material of the transition layer further includes an auxiliary agent, which includes one or a combination of antioxidants and ultraviolet absorbers. The mass ratio of nylon to auxiliary agent is 1:0.01-0.3.

[0020] In some embodiments, the raw materials of the second adhesive layer include maleic anhydride grafted polyethylene and maleic anhydride grafted ethylene-vinyl acetate copolymer (maleic anhydride grafted EVA), and the mass ratio of the maleic anhydride grafted polyethylene to the maleic anhydride grafted ethylene-vinyl acetate copolymer is 1:0.2~4.

[0021] In some specific embodiments, the raw material of the second adhesive layer further includes an additive, which includes one or a combination of antioxidants and ultraviolet absorbers. The mass ratio of the maleic anhydride grafted polyethylene to the additive is 1:0.005-0.3.

[0022] In some specific embodiments, the polyethylene in the maleic anhydride grafted polyethylene used in the transition layer and the second adhesive layer is selected from any one or more of LDPE, LLDPE, HDPE, MDPE, VLDPE and mLLDPE.

[0023] The antioxidant in the first adhesive layer, the transition layer, and the second adhesive layer is one or any combination of antioxidant 1010, antioxidant 1076, antioxidant 168, and antioxidant 264. The ultraviolet absorber in the first adhesive layer, the transition layer, and the second adhesive layer is one or any combination of UV327, UV531, UV770, and UV944.

[0024] In some specific embodiments, the thickness of the first adhesive layer, the transition layer, and the second adhesive layer are 0.01 to 0.05 mm, respectively.

[0025] The second technical solution adopted by the present invention is: a method for preparing the hot melt adhesive film described above, comprising the following steps:

[0026] Step S1: mixing all raw materials of the first adhesive layer, and then extruding and granulating to obtain first adhesive layer pellets;

[0027] Step S2: mixing all the raw materials of the transition layer, and then extruding and granulating to obtain transition layer granules;

[0028] Step S3: mixing all the raw materials of the second adhesive layer, and then extruding and granulating to obtain second adhesive layer pellets;

[0029] Step S4: adding the first adhesive layer pellets, the transition layer pellets, and the second adhesive layer pellets into a co-extrusion device respectively, and co-extruding and compounding them to obtain the hot melt adhesive film.

[0030] Furthermore, the working temperature of the first adhesive layer during the extrusion granulation is 150-200°C, preferably 160-180°C.

[0031] Furthermore, the working temperature of the transition layer for the extrusion granulation is 140-180°C, preferably 150-170°C.

[0032] Furthermore, the working temperature of the second adhesive layer during the extrusion granulation is 140-200°C, preferably 150-170°C.

[0033] Furthermore, the operating temperature of the co-extrusion die of the co-extrusion equipment is 140-190°C, preferably 140-150°C.

[0034] The third technical solution adopted by the present invention is: a composite panel, comprising a metal plate and a PVC waterproof roll bonded to the metal plate by hot-melt adhesive film, wherein the hot-melt adhesive film is the hot-melt adhesive film described above or the hot-melt adhesive film prepared by the above-mentioned preparation method.

[0035] Furthermore, the metal plate is a galvanized metal plate.

[0036] Furthermore, the hot pressing adopts a temperature of 150-180° C., a pressure of 0.4-0.8 MPa, and a time of 10-30 seconds.

[0037] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0038] The hot-melt adhesive film of the present invention has better plasticizer barrier properties, better high-temperature peel strength and more stringent peel strength retention rate after heat aging (90°C / 504h) by redesigning the raw material formula of the first adhesive layer and the transition layer. When the hot-melt adhesive film is used to bond metal and PVC to obtain a composite board, not only does the peel strength basically not decay after long-term use, but the composite board can also be used in more stringent use environments, and is particularly suitable for the peel strength requirements under long-term use conditions such as areas near the equator where outdoor temperatures are high all year round. DETAILED DESCRIPTION

[0039] In response to the problems that the existing hot-melt adhesive films used for bonding metal and PVC have poor high-temperature peel strength and low peel strength retention rate after severe thermal aging, the present invention provides an improved hot-melt adhesive film for bonding metal and PVC, which has better plasticizer barrier properties, good high-temperature peel strength and more severe peel strength retention rate after thermal aging. It can be applied to some areas with high outdoor temperatures all year round and can still meet the standard requirements for 25 years of outdoor use under photovoltaic building integration conditions.

[0040] The main concepts of this invention are: first, copolyester and styrene-acrylonitrile-glycidyl methacrylate are introduced into the first adhesive layer used for bonding to PVC. The epoxy groups of the styrene-acrylonitrile-glycidyl methacrylate react with the carboxylic acid groups of the copolyester, significantly improving the density and cohesive strength of the first adhesive layer and greatly enhancing its resistance to plasticizer migration. Second, nylon, maleic anhydride-grafted polyethylene, and glass flakes are introduced into the transition layer. The glass flakes form a sheet-like shielding layer within the adhesive film, significantly increasing the migration pathways of small molecule plasticizers within the film and significantly reducing their migration speed, while also improving the film's high-temperature resistance. Furthermore, the epoxy groups of the styrene-acrylonitrile-glycidyl methacrylate terpolymer in the first adhesive layer undergo a cross-linking reaction with the anhydride groups of the maleic anhydride-grafted polyethylene in the transition layer, significantly enhancing the bonding strength between the first adhesive layer and the transition layer. The synergistic effect of copolyester, styrene-acrylonitrile-glycidyl methacrylate and glass flakes can greatly improve the high-temperature peel strength of the hot-melt adhesive film and the peel strength retention rate after more severe thermal aging (90℃ / 504h). It can be used in areas with high outdoor temperatures all year round and can still meet the standard requirements for 25 years of outdoor use under photovoltaic building integration conditions.

[0041] A further concept of the present invention is to introduce a maleic anhydride modifier (such as maleic anhydride grafted polyethylene or maleic anhydride grafted ethylene-vinyl acetate copolymer) into the second adhesive layer for metal bonding. The amino groups on the nylon molecular structure in the transition layer can undergo a cross-linking reaction with the anhydride functional groups in the maleic anhydride modifier in the second adhesive layer for metal bonding, thereby improving the bonding strength between the transition layer and the second adhesive layer in the adhesive film.

[0042] With the hot-melt adhesive film designed as described above, a cross-linking reaction will occur between the first adhesive layer, the transition layer, and the second adhesive layer during co-extrusion into a film, thereby greatly increasing the cross-linking density of the film and the bonding strength between the layers of the film, significantly improving the film's resistance to plasticizer migration, and greatly improving the film's high-temperature peel strength and more stringent peel strength retention rate after aging.

[0043] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand and implement the technical solutions of the present invention, but the present invention is not limited to the scope of the examples.

[0044] Unless otherwise specified, the raw materials used in the following examples are from the following sources:

[0045] The copolyester was ES-5 (melt index 15 g / 10 min) from Nantong Xinxing Hot Melt Adhesive Co., Ltd.

[0046] Styrene-acrylonitrile-glycidyl methacrylate was SAG2030 produced by StarBeida (Shanghai) Chemical Materials Co., Ltd.

[0047] The plasticizer is a high-temperature resistant plasticizer, which is an ester of trimellitic anhydride and monohydric alcohol, and is KYC-TM03 from Guangdong Keyuncheng New Materials Co., Ltd.

[0048] The nylon used was A136L from China Hengshen Holding Group Co., Ltd.

[0049] The glass flakes are produced by Hebei Tianshen Glass Flake Co., Ltd. and the specification is 80 mesh.

[0050] The maleic anhydride grafted poly EVA was 30E753 from Dow Chemical.

[0051] The maleic anhydride grafted polyethylene was Bayer 41E755 from Dow Chemical.

[0052] Example 1

[0053] The high-barrier hot-melt adhesive film provided in this embodiment is used for bonding metal and PVC. The hot-melt adhesive film includes a first adhesive layer for bonding with PVC, a second adhesive layer for bonding with metal, and a transition layer provided between the first adhesive layer and the second adhesive layer.

[0054] The raw material formula of the first adhesive layer is as follows:

[0055] The raw material formula of the transition layer is as follows:

[0056] The raw material formula of the second adhesive layer is as follows:

[0057] The hot melt adhesive film in this example was prepared by the following method:

[0058] Step S1: All raw materials for the first adhesive layer are mixed, and then extruded and granulated at an extrusion temperature of 180° C. to obtain first adhesive layer pellets;

[0059] Step S2: all raw materials for the transition layer are mixed, and then extruded and granulated at an extrusion temperature of 160° C. to obtain transition layer granules;

[0060] Step S3: All raw materials for the second adhesive layer are mixed, and then extruded and granulated at an extrusion temperature of 150° C. to obtain second adhesive layer pellets;

[0061] Step S4: Add the first adhesive layer pellets, transition layer pellets, and second adhesive layer pellets into a three-layer co-extrusion composite film blowing machine for co-extrusion at a die head temperature of 140° C. to obtain a hot melt adhesive film, and control the thickness of the first adhesive layer, transition layer, and second adhesive layer to be 0.02 mm respectively.

[0062] Example 2

[0063] The high barrier hot melt adhesive film provided in this embodiment has the same structure as that of Example 1, wherein:

[0064] The raw material formula of the first adhesive layer is as follows:

[0065] The raw material formula of the transition layer is as follows:

[0066] The raw material formula of the second adhesive layer is as follows:

[0067] Example 3

[0068] The high barrier hot melt adhesive film provided in this embodiment is different from that in Example 1 in that:

[0069] The raw material formula of the first adhesive layer is as follows:

[0070] Example 4

[0071] The high barrier hot melt adhesive film provided in this embodiment is different from that in Example 1 in that:

[0072] The raw material formula of the first adhesive layer is as follows:

[0073] Example 5

[0074] The high-barrier hot-melt adhesive film provided in this embodiment is different from that in Example 1 in that 120-mesh glass flakes are used instead in the transition layer.

[0075] Example 6

[0076] The high barrier hot melt adhesive film provided in this embodiment is different from that in Example 1 in that:

[0077] The raw material formula of the first adhesive layer is as follows:

[0078] Comparative Example 1

[0079] The melt adhesive film of this comparative example is basically the same as that of Example 1, except that the copolyester in the first adhesive layer is replaced by ES-7 produced by Nantong Xinxing Hot Melt Adhesive Co., Ltd. with a melt index of 60 g / 10 min.

[0080] Comparative Example 2

[0081] The hot melt adhesive film of this comparative example is basically the same as that of Example 1, except that calcium carbonate of the same mesh size is used in the transition layer instead of glass flakes.

[0082] Comparative Example 3

[0083] The hot melt adhesive film of this comparative example is basically the same as that of Example 1, except that the raw material formula of the first adhesive layer is as follows:

[0084] Comparative Example 4

[0085] The hot melt adhesive film of this comparative example is basically the same as that of Example 1, except that no maleic anhydride grafted polyethylene is added to the transition layer.

[0086] The hot melt adhesive films of Examples 1 to 6 and Comparative Examples 1 to 4 were used to bond metal plates and PVC waterproof membranes, wherein the metal plates were galvanized plates with a thickness of 0.6 mm and the thickness of the PVC waterproof membranes was 0.8 mm. The metal plates, hot melt adhesive films and PVC waterproof membranes were stacked in sequence and then hot-pressed together. The hot pressing temperature was 160°C, the pressure was 0.6 MPa, and the hot pressing time was 20 s.

[0087] Then, referring to the professional standard for building materials and home furnishings JTB T / CBMCA 017-2020, the 180° peel strength (including room temperature peel strength and 70°C peel strength) and the peel strength after heat aging at 90°C / 504h were tested. The results are shown in Table 1.

[0088] Table 1 Performance test results of hot melt adhesive films of Examples 1 to 6 and Comparative Examples 1 to 4

[0089] The hot melt adhesive films of Examples 1 to 6 not only have high peel strength at room temperature, but also have high peel strength at high temperature, and the attenuation of the peel strength after severe thermal aging is basically negligible.

[0090] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0091] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A hot melt adhesive film for bonding metal to PVC, the hot melt adhesive film comprising a first adhesive layer for bonding to the PVC, a second adhesive layer for bonding to the metal, and a transition layer arranged between the first adhesive layer and the second adhesive layer, characterized in that: The raw materials of the first adhesive layer include copolyester and styrene-acrylonitrile-glycidyl methacrylate, and the mass ratio of the copolyester to styrene-acrylonitrile-glycidyl methacrylate is 1:0.5-6; The raw materials of the transition layer include nylon, maleic anhydride grafted polyethylene and glass flakes, and the mass ratio of the nylon, maleic anhydride grafted polyethylene and glass flakes is 1:0.3-3:0.2-3.

2. The hot melt adhesive film according to claim 1, characterized in that: In the first adhesive layer, the mass ratio of the copolyester to styrene-acrylonitrile-glycidyl methacrylate is 1:0.6-2.

5.

3. The hot melt adhesive film according to claim 1 or 2, characterized in that: The copolyester is a thermoplastic copolyether ester, and its melt index is 10-20 g / 10 min.

4. The hot melt adhesive film according to claim 1, characterized in that: The raw material of the first adhesive layer also includes a high temperature resistant plasticizer, and the mass ratio of the copolyester to the high temperature resistant plasticizer is 1:0.01-4.

5. The hot melt adhesive film according to claim 4, characterized in that: The high temperature resistant plasticizer is an ester of trimellitic anhydride and monohydric alcohol; and / or the mass ratio of the copolyester to the high temperature resistant plasticizer is 1:0.2-1.

5.

6. The hot melt adhesive film according to claim 1, characterized in that: The raw material of the first adhesive layer also includes an auxiliary agent, which includes one or a combination of antioxidants and ultraviolet absorbers. The mass ratio of the copolyester to the auxiliary agent is 1:0.01-0.

3.

7. The hot melt adhesive film according to claim 1, characterized in that: The mass ratio of the nylon, maleic anhydride grafted polyethylene and glass flakes is 1:0.5-1.5:0.5-1.

5.

8. The hot melt adhesive film according to claim 7, characterized in that: The crystallinity of the nylon is above 62%; and / or the raw material of the transition layer further includes an auxiliary agent, the auxiliary agent includes one or a combination of antioxidants and ultraviolet absorbers, and the mass ratio of the nylon to the auxiliary agent is 1:0.01-0.

3.

9. The hot melt adhesive film according to claim 1, characterized in that: The particle size of the glass flakes is 70 to 130 meshes, and preferably, the particle size of the glass flakes is 70 to 90 meshes.

10. The hot melt adhesive film according to claim 1, characterized in that: The raw materials of the second adhesive layer include maleic anhydride grafted polyethylene and maleic anhydride grafted ethylene-vinyl acetate copolymer, and the mass ratio of the maleic anhydride grafted polyethylene to the maleic anhydride grafted ethylene-vinyl acetate copolymer is 1:0.2-4.

11. The hot melt adhesive film according to claim 10, characterized in that: The raw material of the second adhesive layer also includes an auxiliary agent, which includes one or a combination of antioxidants and ultraviolet absorbers. The mass ratio of the maleic anhydride grafted polyethylene to the auxiliary agent is 1:0.005-0.

3.

12. The hot melt adhesive film according to claim 10, characterized in that: The polyethylene in the maleic anhydride grafted polyethylene used in the transition layer and the second adhesive layer is selected from any one or more of LDPE, LLDPE, HDPE, MDPE, VLDPE and mLLDPE.

13. The hot melt adhesive film according to claim 1, characterized in that: The thickness of the first adhesive layer, the transition layer and the second adhesive layer are 0.01-0.05 mm respectively.

14. The hot melt adhesive film according to any one of claims 1 to 2 and 4 to 13, characterized in that: The preparation method of the hot melt adhesive film comprises the following steps: Step S1, mixing all raw materials of the first adhesive layer, and then extruding and granulating to obtain first adhesive layer pellets; Step S2, mixing all the raw materials of the transition layer, and then extruding and granulating to obtain transition layer pellets; Step S3, mixing all the raw materials of the second adhesive layer, and then extruding and granulating to obtain second adhesive layer pellets; Step S4, adding the first adhesive layer pellets, the transition layer pellets, and the second adhesive layer pellets into a co-extrusion device respectively, and co-extruding and compounding them to obtain the hot melt adhesive film.

15. The hot melt adhesive film according to claim 14, characterized in that: The working temperature of the first adhesive layer for extrusion granulation is 150-200°C, the working temperature of the transition layer for extrusion granulation is 140-180°C, the working temperature of the second adhesive layer for extrusion granulation is 140-200°C, and the working temperature of the coextrusion die of the coextrusion equipment is 140-190°C.

16. A method for preparing a hot melt adhesive film according to any one of claims 1 to 15, characterized in that: The following steps are involved: Step S1, mixing all raw materials of the first adhesive layer, and then extruding and granulating to obtain first adhesive layer pellets; Step S2, mixing all the raw materials of the transition layer, and then extruding and granulating to obtain transition layer pellets; Step S3, mixing all the raw materials of the second adhesive layer, and then extruding and granulating to obtain second adhesive layer pellets; Step S4: Add the first adhesive layer pellets, transition layer pellets, and second adhesive layer pellets into the co-extrusion equipment The hot melt adhesive film is obtained by co-extrusion and compounding.

17. A composite board, comprising a metal plate and a PVC waterproof coiled material bonded to the metal plate by hot-melt adhesive film, characterized in that: The hot melt adhesive film is the hot melt adhesive film according to any one of claims 1 to 15 or the hot melt adhesive film prepared by the preparation method of claim 16.

18. The composite panel according to claim 17, characterized in that: The metal sheet is a galvanized metal sheet; and / or, The temperature used for the hot pressing is 150-180° C., the pressure is 0.4-0.8 MPa, and the time is 10-30 seconds.

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