A high-barrier hot-melt adhesive film, its preparation method and composite board

Abstract

The present invention relates to a high-barrier hot melt adhesive film, a preparation method thereof and a composite board. 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 disposed between the first adhesive layer and the second adhesive layer. The raw materials of the first adhesive layer include copolyester and styrene-acrylonitrile-glycidyl methacrylate, and the raw materials of the transition layer include nylon, maleic anhydride grafted polyethylene and glass flakes. By redesigning the raw material formula of the first adhesive layer and the transition layer, the hot melt adhesive film of the present invention has better plasticizer barrier performance, better high-temperature peel strength and higher peel strength retention rate after more severe heat aging. The composite board obtained by using the hot melt adhesive film to bond metal and PVC can be used in more severe use environments, and is particularly suitable for the requirements of peel strength under long-term use conditions with relatively high outdoor temperatures all year round in areas near the equator and the like.

Description

Technical Field

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

[0002] Due to its soft texture and excellent welding performance, PVC waterproof coiled materials are widely used in the waterproof system of light steel roofs. The traditional method is to use mechanical fixation and full adhesion methods to combine PVC waterproof coiled materials to metal roofs. However, there are problems such as solvent volatilization and difficulty in controlling the amount of glue brushing.

[0003] Patent documents disclose that a hot melt adhesive film is used to hot press and composite PVC waterproof coiled materials and metal plates together to form a PVC metal composite board, which greatly saves the construction cost of the waterproof system for light steel single-layer roofs and roof repair projects, improves the construction quality, and shortens the construction period.

[0004] Chinese Patent CN109207073A discloses a three-layer composite hot melt adhesive film for bonding metal / polar functional plastics and its processing technology. The three-layer composite hot melt adhesive film includes an inner adhesive film bonded to metal, an outer adhesive film bonded to polar functional plastics, and a transition layer connecting the inner adhesive and the outer adhesive. The outer adhesive film bonded to polar functional plastics in this patent contains polar materials such as maleic anhydride grafted polyethylene or maleic anhydride grafted polyethylene copolymer, copolyester, and tackifying resin. However, the grafting rate of maleic anhydride on polyethylene or polyethylene copolymer is limited, and the ability to resist a large amount of polar plasticizers in polar substrates such as PVC is very limited.

[0005] Chinese Patent CN114479682A discloses a hot melt adhesive film for bonding metal and PVC and a preparation method thereof. In the first adhesive layer bonded to PVC, a polyethylene-acrylate-maleic anhydride terpolymer and a maleic anhydride grafted C5 / C9 copolymer resin are used. By utilizing the synergistic effect between the polyethylene-acrylate-maleic anhydride terpolymer and the maleic anhydride grafted C5 / C9 copolymer resin, a firm barrier is formed in the first adhesive layer, preventing the migration of plasticizers in PVC to the first adhesive layer, improving the anti-plasticizer effect of the hot melt adhesive film. After long-term use, the peel strength basically does not decay. However, it still cannot meet the use requirements for some harsh environments, such as still being difficult to meet the peel strength requirements under long-term use conditions in areas with relatively high outdoor temperatures (such as areas near the equator with high temperatures all year round). Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an improved hot melt adhesive film in view of the deficiencies of the prior art. This hot melt adhesive film has better barrier properties against plasticizers, better high-temperature peel strength, and a higher peel strength retention rate after more severe heat aging.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A hot melt adhesive film for bonding between metal and PVC, the hot melt adhesive film includes a first adhesive layer for bonding with the PVC, a second adhesive layer for bonding with the metal, and an intermediate layer disposed between the first adhesive layer and the second adhesive layer. 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;

[0009] The raw materials of the intermediate layer include nylon, maleic anhydride grafted polyethylene and glass flakes, and the mass ratio of nylon, maleic anhydride grafted polyethylene and glass flakes is 1:0.3-3:0.2-3.

[0010] 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.

[0011] In some specific embodiments, the copolyester is a thermoplastic copolyether ester, and its melt index is 10-20 g / 10 min (2.16 Kg / 160 °C). Such as ES-5 (melt index is 15 g / 10 min) of Nantong GCL Hot Melt Adhesive Co., Ltd.

[0012] In some embodiments, the raw materials of the first adhesive layer further include a high-temperature resistant plasticizer, and the mass ratio of the copolyester to the high-temperature resistant plasticizer is 1:0.01-4.

[0013] In some specific embodiments, the high-temperature resistant plasticizer is an esterified product 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.

[0014] In some specific embodiments, the raw materials of the first adhesive layer further include an additive, and the additive includes one or a combination of antioxidants and ultraviolet absorbers, and the mass ratio of the copolyester to the additive is 1:0.01-0.3.

[0015] In some preferred embodiments, the mass ratio of nylon, maleic anhydride grafted polyethylene and glass flakes is 1:0.5-1.5:0.5-1.5.

[0016] In some specific embodiments, the crystallinity of the nylon is above 62%, and the crystallinity is measured by X-ray diffraction method.

[0017] In some specific embodiments, the particle size of the glass flakes is 70-130 mesh. Preferably, the particle size of the glass flakes is 70-90 mesh.

[0018] In some specific embodiments, the raw materials of the transition layer further include an auxiliary agent, and the auxiliary agent includes one or a combination of antioxidants and ultraviolet absorbers. The mass ratio of the nylon to the auxiliary agent is 1:0.01 to 0.3.

[0019] 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 to 4.

[0020] In some specific embodiments, the raw materials of the second adhesive layer further include an auxiliary agent, and the auxiliary agent 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 to 0.3.

[0021] 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.

[0022] 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.

[0023] In some specific embodiments, the thicknesses of the first adhesive layer, the transition layer, and the second adhesive layer are 0.01 to 0.05 mm respectively.

[0024] The second technical solution adopted by the present invention is: a method for preparing the above-mentioned hot melt adhesive film, comprising the following steps:

[0025] Step S1: Mix all the raw materials of the first adhesive layer, and then extrude and granulate to obtain the first adhesive layer pellets;

[0026] Step S2: Mix all the raw materials of the transition layer, and then extrude and granulate to obtain the transition layer pellets;

[0027] Step S3: Mix all the raw materials of the second adhesive layer, and then extrude and granulate to obtain the second adhesive layer pellets;

[0028] Step S4: Add the first adhesive layer pellets, the transition layer pellets, and the second adhesive layer pellets into a co-extrusion device respectively, and co-extrude and compound to obtain the hot melt adhesive film.

[0029] Further, the working temperature for the extrusion granulation of the first adhesive layer is 150 - 200 °C, and the preferred temperature is 160 - 180 °C.

[0030] Further, the working temperature for the extrusion granulation of the transition layer is 140 - 180 °C, and the preferred temperature is 150 - 170 °C.

[0031] Further, the working temperature for the extrusion granulation of the second adhesive layer is 140 - 200 °C, and the preferred temperature is 150 - 170 °C.

[0032] Further, the working temperature of the co - extrusion die head of the co - extrusion equipment is 140 - 190 °C, and the preferred temperature is 140 - 150 °C.

[0033] The third technical solution adopted by the present invention is: a composite board, including a metal plate and a PVC waterproof coiled material thermally pressed and bonded to the metal plate through a hot - melt adhesive film, where the hot - melt adhesive film is the above - mentioned hot - melt adhesive film or the hot - melt adhesive film prepared by the above - mentioned preparation method.

[0034] Further, the metal layer is a galvanized metal plate.

[0035] Further, the temperature used for the thermal pressing is 150 - 180 °C, the pressure is 0.4 - 0.8 MPa, and the time is 10 - 30 s.

[0036] Due to the application of the above - mentioned technical solution, the present invention has the following advantages compared with the prior art:

[0037] By redesigning the raw material formula of the first adhesive layer and the transition layer, the hot - melt adhesive film of the present invention has better plasticizer barrier performance, better high - temperature peel strength, and a higher peel strength retention rate after more severe heat aging (90 °C / 504 h). The composite board obtained by using this hot - melt adhesive film to bond metal and PVC not only has basically no attenuation of the peel strength after long - term use, but also can be used in more severe use environments, and is especially suitable for the peel strength requirements under long - term use conditions with high outdoor temperatures all year round near the equator and other areas. Detailed Embodiments

[0038] Aiming at the problems of poor high - temperature peel strength and low peel strength retention rate after severe heat aging of the existing hot - melt adhesive film for bonding metal and PVC, the present invention provides an improved hot - melt adhesive film for bonding metal and PVC, which has better plasticizer barrier performance, better high - temperature peel strength, and a higher peel strength retention rate after more severe heat aging, and can be applied to some areas with high outdoor temperatures all year round, and still can meet the standard requirements for 25 - year outdoor use under the conditions of building - integrated photovoltaics.

[0039] The main concept of the present invention lies in: on the one hand, copolyester and styrene-acrylonitrile-glycidyl methacrylate are introduced into the first adhesive layer for bonding with PVC. By using the epoxy group of styrene-acrylonitrile-glycidyl methacrylate to react with the carboxylic acid functional group of copolyester, the density and cohesive strength of the first adhesive layer are significantly improved, and the anti-plasticizer migration performance of the first adhesive layer is greatly enhanced. On the other hand, nylon, maleic anhydride grafted polyethylene and glass flakes are introduced into the transition layer. Among them, the glass flakes can form a flaky shielding layer inside the adhesive film, significantly increasing the migration path of small molecule plasticizers in the adhesive film, greatly reducing the migration speed of plasticizers, and at the same time improving the high temperature resistance of the adhesive film. In addition, the epoxy functional group in the styrene-acrylonitrile-glycidyl methacrylate terpolymer in the first adhesive layer can crosslink with the anhydride functional group in the maleic anhydride grafted polyethylene in the transition layer, greatly improving 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°C / 504h), and it can still meet the standard requirements for 25-year outdoor use under the conditions of photovoltaic building integration in areas with relatively high outdoor temperatures all year round.

[0040] A further concept of the present invention lies in introducing maleic anhydride modifiers (such as maleic anhydride grafted polyethylene, maleic anhydride grafted ethylene-vinyl acetate copolymer) into the second adhesive layer for bonding with metal. The amine group on the molecular structure of nylon in the transition layer can crosslink with the anhydride functional group in the maleic anhydride modifier in the second adhesive layer for bonding with metal, thereby improving the bonding strength between the transition layer and the second adhesive layer in the adhesive film.

[0041] For the hot melt adhesive film designed as above, crosslinking reactions will occur between the first adhesive layer, the transition layer and the second adhesive layer during coextrusion film formation, greatly improving the crosslinking density of the adhesive film and the bonding strength between the layers of the adhesive film, significantly enhancing the plasticizer migration resistance performance of the adhesive film, and greatly improving the high temperature peel strength of the adhesive film and the peel strength retention rate after more severe aging resistance.

[0042] The technical solutions of the present invention will be described in detail below 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 described examples.

[0043] The raw materials used in the following examples are sourced as follows unless otherwise specified:

[0044] The copolyester is ES-5 (melt index is 15 g / 10 min) of Nantong GCL Hot Melt Adhesive Co., Ltd.

[0045] The styrene-acrylonitrile-glycidyl methacrylate is SAG2030 of Xingbeida (Shanghai) Chemical Materials Co., Ltd.

[0046] The plasticizer is a high-temperature resistant plasticizer, which is an esterified product of trimellitic anhydride and monohydric alcohol, and is KYC-TM03 of Guangdong Keyuncheng New Materials Co., Ltd.

[0047] The nylon is A136L of China Hengshen Holding Group Co., Ltd.

[0048] The glass flakes are produced by Hebei Tianshen Glass Flakes Co., Ltd. and the specification is 80 mesh.

[0049] The maleic anhydride grafted poly-EVA is 30E753 of Dow Chemical Company.

[0050] The maleic anhydride grafted polyethylene is Bynel 41E755 of Dow Chemical Company.

[0051] Example 1

[0052] The high-barrier hot-melt adhesive film provided in this example is used for bonding between 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 disposed between the first adhesive layer and the second adhesive layer. Among them,

[0053] The raw material formula of the first adhesive layer is as follows:

[0054]

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

[0056]

[0057] The raw material formula of the second adhesive layer is as follows:

[0058]

[0059] The hot-melt adhesive film in this example is prepared by the following method:

[0060] Step S1: Mix all the raw materials of the first adhesive layer, and then extrude and pelletize them. The extrusion temperature is 180 °C to obtain the pellets of the first adhesive layer;

[0061] Step S2: Mix all the raw materials of the transition layer, and then extrude and pelletize them. The extrusion temperature is 160 °C to obtain the pellets of the transition layer;

[0062] Step S3: Mix all the raw materials of the second adhesive layer, and then extrude and pelletize them. The extrusion temperature is 150 °C to obtain the pellets of the second adhesive layer;

[0063] Step S4: Add the first adhesive layer pellets, transition layer pellets, and second adhesive layer pellets into a three-layer coextrusion compounding blown film machine for coextrusion. The temperature of the coextrusion die head is 140°C to obtain a hot melt adhesive film, and control the thicknesses of the first adhesive layer, transition layer, and second adhesive layer to be 0.02 mm respectively.

[0064] Example 2

[0065] The high-barrier hot melt adhesive film provided in this example has the same structure as that in Example 1, where:

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

[0067]

[0068] The raw material formula of the transition layer is as follows:

[0069]

[0070] The raw material formula of the second adhesive layer is as follows:

[0071]

[0072] Example 3

[0073] The high-barrier hot melt adhesive film provided in this example is different from that in Example 1 in that:

[0074] The raw material formula of the first adhesive layer is as follows:

[0075]

[0076] Example 4

[0077] The high-barrier hot melt adhesive film provided in this example is different from that in Example 1 in that:

[0078] The raw material formula of the first adhesive layer is as follows:

[0079]

[0080]

[0081] Example 5

[0082] The high-barrier hot melt adhesive film provided in this example is different from that in Example 1 in that: 120-mesh glass flakes are used in the transition layer instead.

[0083] Example 6

[0084] The high-barrier hot melt adhesive film provided in this example is different from that in Example 1 in that:

[0085] The raw material formula of the first adhesive layer is as follows:

[0086]

[0087] Comparative Example 1

[0088] The molten 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 of Nantong GCL Hot Melt Adhesive Co., Ltd. with a melt index of 60 g / 10 min.

[0089] Comparative Example 2

[0090] 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 number is used to replace glass flakes in the transition layer.

[0091] Comparative Example 3

[0092] 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:

[0093]

[0094] Comparative Example 4

[0095] The hot melt adhesive film of this comparative example is basically the same as that of Example 1, except that: maleic anhydride grafted polyethylene is not added in the transition layer.

[0096] The hot melt adhesive films of Examples 1 to 6 and Comparative Examples 1 to 4 are used to bond a metal plate and a PVC waterproof coil. Among them, the metal plate is a galvanized sheet with a thickness of 0.6 mm, and the thickness of the PVC waterproof coil is 0.8 mm. The metal plate, the hot melt adhesive film and the PVC waterproof coil are stacked in sequence, and then hot-pressed and laminated together. The hot-pressing temperature is 160 °C, the pressure is 0.6 MPa, and the hot-pressing time is 20 s.

[0097] Then, refer to the professional standard of building materials and home furnishing JTB T / CBMCA 017-2020 to test the 180° peel strength (including the peel strength at normal temperature and the peel strength at 70 °C) and the peel strength after 90 °C / 504 h heat aging. The results are shown in Table 1.

[0098] Table 1 Performance test results of the hot melt adhesive films of Examples 1 to 6 and Comparative Examples 1 to 4

[0099]

[0100] The hot melt adhesive films of Examples 1 to 6 not only have a high peel strength at normal temperature, but also have a high peel strength at high temperature, and the attenuation of the peel strength after severe heat aging can be basically ignored.

[0101] The above embodiments are only used to illustrate the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

[0102] The endpoints and any values disclosed in this text are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this text.

Claims

1. A hot melt adhesive film for bonding between metal and PVC, the hot melt adhesive film comprising a first adhesive layer for bonding with the PVC, a second adhesive layer for bonding with the metal, and a transition layer disposed 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 nylon, maleic anhydride grafted polyethylene and glass flakes is 1:0.3-3:0.2-3; The copolyester is a thermoplastic copolyether ester, and its melt index is 10-20 g / 10 min. The melt index is tested under the condition of 2.16 Kg / 160 °C.

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, wherein: The raw materials of the first adhesive layer further include a high-temperature resistant plasticizer, and the mass ratio of the copolyester to the high-temperature resistant plasticizer is 1:0.01-4.

4. The hot melt adhesive film according to claim 3, characterized in that: The high-temperature resistant plasticizer is an esterification product of trimellitic anhydride and a monohydric alcohol.

5. The hot melt adhesive film according to claim 3, characterized in that: 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, wherein: The raw materials of the first adhesive layer further include an additive. The additive includes one or a combination of several of an antioxidant and an ultraviolet absorber. The mass ratio of the copolyester to the additive is 1:0.01-0.

3.

7. The hot melt adhesive film according to claim 1, characterized in that: The mass ratio of 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, wherein: The crystallinity of the nylon is above 62%; and / or, the raw materials of the transition layer further include an additive. The additive includes one or a combination of several of an antioxidant and an ultraviolet absorber. The mass ratio of the nylon to the additive is 1:0.01-0.

3.

9. 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 maleic anhydride grafted polyethylene to maleic anhydride grafted ethylene-vinyl acetate copolymer is 1:0.2-4.

10. The hot melt adhesive film according to claim 9, characterized in that: The raw materials of the second adhesive layer further include an additive. The additive includes one or a combination of several of an antioxidant and an ultraviolet absorber. The mass ratio of maleic anhydride grafted polyethylene to the additive is 1:0.005-0.

3.

11. The hot melt adhesive film according to claim 1, wherein: The thicknesses of the first adhesive layer, the transition layer and the second adhesive layer are 0.01-0.05 mm respectively.

12. The hot melt adhesive film according to any one of claims 1 to 11, characterized in that: The preparation method of the hot-melt adhesive film includes the following steps: Step S1: Mix all the raw materials of the first adhesive layer, and then extrude and pelletize to obtain the pellets of the first adhesive layer; Step S2: Mix all the raw materials of the transition layer, and then extrude and pelletize to obtain the pellets of the transition layer; Step S3: Mix all the raw materials of the second adhesive layer, and then extrude and pelletize to obtain the pellets of the second adhesive layer; Step S4: Add the pellets of the first adhesive layer, the pellets of the transition layer and the pellets of the second adhesive layer into a co-extrusion device respectively, and co-extrude and compound to obtain the hot-melt adhesive film.

13. The hot melt adhesive film according to claim 12, wherein: The working temperature for the extrusion granulation of the first adhesive layer is 150 - 200 °C, the working temperature for the extrusion granulation of the transition layer is 140 - 180 °C, the working temperature for the extrusion granulation of the second adhesive layer is 140 - 200 °C, and the working temperature of the coextrusion die head of the coextrusion equipment is 140 - 190 °C.

14. A method for preparing the hot melt adhesive film according to any one of claims 1 to 13, characterized in that, It includes the following steps: Step S1: Mix all the raw materials of the first adhesive layer, and then perform extrusion granulation to obtain the first adhesive layer pellets; Step S2: Mix all the raw materials of the transition layer, and then perform extrusion granulation to obtain the transition layer pellets; Step S3: Mix all the raw materials of the second adhesive layer, and then perform extrusion granulation to obtain the second adhesive layer pellets; Step S4: Add the first adhesive layer pellets, transition layer pellets, and second adhesive layer pellets into the coextrusion equipment respectively, and coextrusion composite to obtain the hot melt adhesive film.

15. A composite board, comprising a metal plate and a PVC waterproof coil bonded to the metal plate by hot pressing with a hot melt adhesive film, characterized in that: The hot melt adhesive film adopts the hot melt adhesive film described in any one of claims 1 - 13 or the hot melt adhesive film prepared by the preparation method of claim 14.

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