Hot melt adhesive film for bonding TPO (thermoplastic polyolefin) and epoxy plate and preparation method of hot melt adhesive film

Abstract

The invention relates to a hot melt adhesive film for bonding TPO and an epoxy plate and a preparation method thereof, the hot melt adhesive film comprises the following raw materials by mass: 10-30 parts of a polyolefin elastomer, 20-40 parts of synthetic rubber, 10-30 parts of modified synthetic rubber, 10-30 parts of tackifying resin, 10-30 parts of softening oil, and 1-5 parts of a cross-linking agent. The modified synthetic rubber is a mixture of maleic anhydride grafted SEBS rubber and epoxy modified SBS rubber; uniformly mixing the polyolefin elastomer, the synthetic rubber, the modified synthetic rubber, the tackifying resin and the softening oil, and granulating through a granulator; and uniformly mixing a cross-linking agent and the obtained particles, putting the mixture into a double-screw extruder, and carrying out melt extrusion to obtain the hot melt adhesive film. The hot melt adhesive film disclosed by the invention has high bonding strength on TPO and epoxy plates, and is simple in preparation process and convenient to use.

Description

Technical Field

[0001] This invention belongs to the field of hot melt adhesive film preparation technology, specifically relating to a hot melt adhesive film for bonding TPO and epoxy boards and its preparation method. Background Technology

[0002] TPO materials are recyclable, safe, and environmentally friendly, and possess excellent resistance to aging, pollution, wear, and UV radiation, making them suitable as an outer covering. Epoxy sheets provide rigidity, strength, and dimensional stability, serving as a structural framework that bears the main loads and maintains its shape. Combining TPO materials and epoxy sheets allows for the simultaneous achievement of both rigid structural support and soft protection and aesthetics in a single component, primarily used in the automotive industry, such as in new energy vehicle battery pack housings, door modules, and front-end brackets.

[0003] TPO and epoxy boards have significantly different polarities, making bonding with commonly used adhesives less than ideal. Currently, the main method involves surface treatment of the TPO material followed by bonding with liquid adhesives such as polyurethane or epoxy. However, this method presents challenges such as environmental pollution and complex procedures.

[0004] Patent CN120699552A discloses a hot melt adhesive film for TPO waterproof membranes and its preparation method. This hot melt adhesive film is made from resin with unsaturated functional groups, rubber, tackifying resin, softener, antioxidant, and UV absorber. This hot melt adhesive film is suitable for non-polar TPO materials, but its adhesion to polar epoxy sheets is very poor. Patent CN115044311A discloses a high-temperature resistant hot melt adhesive film and its preparation method. This hot melt adhesive film includes a first layer for metal bonding, a second layer for non-metal bonding, and a transition layer between the two layers. The metal bonding layer mainly uses epoxy resin and a latent curing agent, the non-metal bonding layer mainly uses PE resin, SEBS rubber, and POE resin, and the transition layer mainly uses phenoxy resin, EVA resin, and maleic anhydride-grafted polyolefin resin. This multi-layered adhesive film design enables the bonding of polar and non-polar materials. However, the preparation process of this hot melt adhesive film is complex, and its bonding strength is slightly insufficient, which cannot meet the requirements of some industries and may not be suitable for bonding TPO and epoxy boards. Summary of the Invention

[0005] The purpose of this invention is to provide a hot melt adhesive film for bonding TPO and epoxy boards, which has high bonding strength to TPO and epoxy boards.

[0006] The technical solution adopted by this invention to solve the above problems is: a hot melt adhesive film for bonding TPO and epoxy boards, comprising the following raw materials in parts by weight: 10-30 parts of polyolefin elastomer 20-40 parts of synthetic rubber 10-30 parts of modified synthetic rubber 10-30 parts of tackifying resin 10-30 parts softening oil 1-5 parts of crosslinking agent The modified synthetic rubber is a mixture of maleic anhydride-grafted SEBS rubber and epoxy-modified SBS rubber.

[0007] Preferably, the polyolefin elastomer is one or more of ethylene-propylene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer, and the melt index of the polyolefin elastomer at 190°C and 2.16 kg is 2-50 g / 10 min.

[0008] Preferably, the synthetic rubber is one or more of SBS rubber and SEBS rubber.

[0009] Preferably, the mass ratio of the maleic anhydride-grafted SEBS rubber to the epoxy-modified SBS rubber is 1:0.7-1.5.

[0010] Preferably, the grafting rate of the maleic anhydride-grafted SEBS rubber is 0.5-3%; and the epoxy equivalent of the epoxy-modified SBS rubber is 800-2500 g / eq.

[0011] Preferably, the tackifying resin is one or more of petroleum resin and terpene phenol resin.

[0012] More preferably, the petroleum resin has a softening point of 90-120℃; the terpene phenol resin has a softening point of 95-135℃ and a hydroxyl value of 20-50 mg KOH / g.

[0013] Preferably, the softening oil is a naphthenic softening oil.

[0014] Preferably, the crosslinking agent is an amino-terminated isocyanate.

[0015] Another object of the present invention is to provide a method for preparing a hot melt adhesive film for bonding TPO and epoxy boards, comprising the following steps: 1) Weigh the raw materials of each component according to the proportions; 2) Mix the polyolefin elastomer, synthetic rubber, modified synthetic rubber, tackifying resin and softening oil weighed in step 1) evenly and then granulate them using a granulator. 3) After the crosslinking agent weighed in step 1) and the particles obtained in step 2) are mixed evenly, they are fed into a twin-screw extruder and melt-extruded at a certain temperature to form a film.

[0016] Compared with the prior art, the advantages of the present invention are as follows: The hot melt adhesive film of the present invention has high bonding strength to TPO and epoxy boards, is simple to prepare, and does not require any surface treatment of the materials before bonding, making it convenient to use. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments.

[0018] The following are some of the raw materials used in the embodiments and comparative examples of this invention: The polyolefin elastomer may be, but is not limited to, one or more of Dow's ENGAGE8400, ENGAGE8401, ENGAGE8402, and ENGAGE8411, and ExxonMobil's VM6202 and VM6502.

[0019] The synthetic rubber is preferably one or more of SBS rubber and SEBS rubber; wherein the SBS rubber may be, but is not limited to, D1102, D1118, D1155, and D0243 of Kraton Polymer; and the SEBS rubber may be, but is not limited to, one or more of G1657 and G1726 of Kraton Polymer.

[0020] The modified synthetic rubber is preferably a mixture of maleic anhydride-grafted SEBS rubber and epoxy-modified SBS rubber; wherein the maleic anhydride-grafted SEBS rubber may be, but is not limited to, FG1901G and FG1924G from Kraton Polymers; and the epoxy-modified SBS rubber may be, but is not limited to, EPOFRIEND AT501 and EPOFRIEND CT310 from Daicel.

[0021] The tackifying resin is preferably one or more of petroleum resin and terpene phenol resin; wherein the petroleum resin may be, but is not limited to, ExxonMobil's Escorez 5300, Escorez 5400, and Escorez 5415; and the terpene phenol resin may be, but is not limited to, DRT's Detophene T105, Detophene T115, and Detophene T135.

[0022] The softening oil may be, but is not limited to, one or more of Suzhou Hesen's KN4006 and KN4010.

[0023] The crosslinking agent is preferably an amino-terminated isocyanate, which is prepared by the method described in patent US6348548B1. The isocyanate may be, but is not limited to, Rhein Chemicals' Desmodur TT and Desmodur RC, and the polyamine polymer used for capping may be, but is not limited to, Huntsman's D230 and T403. Example 1

[0024] A method for preparing a hot melt adhesive film for bonding TPO and epoxy boards, the method comprising the following process steps: 1) Weigh out 20 parts by weight of polyolefin elastomer ENGAGE8402, 25 parts of SBS rubber D1102, 7 parts of maleic anhydride-grafted SEBS rubber FG1901G, 12 parts of epoxy-modified SBS rubber EPOFRIEND AT501; 8 parts of petroleum resin Escorez5400, 10 parts of terpene phenol resin Dertophene T115, 15 parts of softening oil KN4010, and 3 parts of crosslinking agent. 2) Mix the polyolefin elastomer, SBS rubber, maleic anhydride-grafted SEBS rubber, epoxy-modified SBS rubber, petroleum resin, terpene phenolic resin and softening oil weighed in step 1) evenly and then granulate them at 200°C using a granulator. 3) After the crosslinking agent weighed in step 1) and the particles obtained in step 2) are mixed evenly, they are fed into a twin-screw extruder and melt-extruded at 120°C to form a film. Example 2

[0025] A method for preparing a hot melt adhesive film for bonding TPO and epoxy boards, the method comprising the following process steps: 1) Weigh out 20 parts of polyolefin elastomer ENGAGE8411, 20 parts of SEBS rubber G1657, 15 parts of maleic anhydride-grafted SEBS rubber FG1901G, 9 parts of epoxy-modified SBS rubber EPOFRIEND AT501, 8 parts of petroleum resin Escorez5415, 12 parts of terpene phenol resin Dertophene T135, 14 parts of softening oil KN4010, and 2 parts of crosslinking agent by mass fraction. 2) Mix the polyolefin elastomer, SEBS rubber, maleic anhydride-grafted SEBS rubber, epoxy-modified SBS rubber, petroleum resin, terpene phenolic resin and softening oil weighed in step 1) evenly and then granulate them at 200°C using a granulator. 3) After the crosslinking agent weighed in step 1) and the particles obtained in step 2) are mixed evenly, they are fed into a twin-screw extruder and melt-extruded at 120°C to form a film. Example 3

[0026] A method for preparing a hot melt adhesive film for bonding TPO and epoxy boards, the method comprising the following process steps: 1) Weigh out 14 parts of polyolefin elastomer ENGAGE8411, 11 parts of SBS rubber D0243, 15 parts of SEBS rubber G1657, 10 parts of maleic anhydride-grafted SEBS rubber FG1901G, 12 parts of epoxy-modified SBS rubber EPOFRIEND AT501, 7 parts of petroleum resin Escorez5415, 8 parts of terpene phenol resin Dertophene T135, 20 parts of softening oil KN4010, and 3 parts of crosslinking agent by mass fraction. 2) Mix the polyolefin elastomer, SBS rubber, SEBS rubber, maleic anhydride-grafted SEBS rubber, epoxy-modified SBS rubber, petroleum resin, terpene phenolic resin and softening oil weighed in step 1) evenly and then granulate them at 200°C using a granulator. 3) After the crosslinking agent weighed in step 1) and the particles obtained in step 2) are mixed evenly, they are fed into a twin-screw extruder and melt-extruded at 120°C to form a film.

[0027] Comparative Example 1 The only difference from Example 1 is that 3 parts of crosslinking agent are replaced with 3 parts of Evonik Chemical's latent curing agent Dicyanex 1400F.

[0028] Comparative Example 2 The only difference from Example 1 is that 7 parts of maleic anhydride-grafted SEBS rubber FG1901G and 12 parts of epoxy-modified SBS rubber EPOFRIEND AT501 are replaced with 19 parts of epoxy-modified SBS rubber EPOFRIEND AT501.

[0029] Comparative Example 3 The only difference from Example 1 is that, except that 7 parts of maleic anhydride-grafted SEBS rubber FG1901G and 12 parts of epoxy-modified SBS rubber EPOFRIEND AT501 are replaced with 19 parts of maleic anhydride-grafted SEBS rubber FG1901G.

[0030] Comparative Example 4 The only difference from Example 1 is that steps 2) and 3) in the process steps are changed to mixing the raw materials weighed in step 1) evenly and feeding them into a twin-screw extruder, and then melting and extruding them at 200°C to form a film.

[0031] The 0.1 mm thick hot melt adhesive films prepared in Examples 1-3 and Comparative Examples 1-4 were laminated onto TPO and 3240 epoxy boards under a lamination temperature of 160°C for 1 min. The peel strength was tested, and the experimental results are shown in Table 1. Table 1. Peel strength test results of hot melt adhesive film bonding TPO and epoxy boards in the examples and comparative examples.

[0032] As shown in Table 1, the hot melt adhesive films prepared in Examples 1-3 of this invention exhibit high bonding strength to TPO and epoxy sheets. Examples 1 and Comparative Example 1 show that commonly used latent epoxy curing agents can also improve the bonding strength of the adhesive film, but these curing agents generally require a long hot-pressing time. Examples 1 and Comparative Examples 2-3 show that maleic anhydride-grafted SEBS rubber and epoxy-modified SBS rubber have a synergistic effect on peel strength. Examples 1 and Comparative Example 4 show that uniformly mixing and granulating the polyolefin elastomer, SBS rubber, maleic anhydride-grafted SEBS rubber, epoxy-modified SBS rubber, petroleum resin, terpene phenolic resin, and softening oil before forming a film with a crosslinking agent can improve peel strength. This is because the crosslinking agent decomposes at high temperatures to form isocyanate groups that can react with epoxy sheets. The isocyanate groups obtained from the decomposition of the crosslinking agent lose their reactivity upon prolonged contact with air; therefore, it is necessary to plasticize the rubber first to reduce the temperature during the final film formation.

[0033] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A hot melt adhesive film for bonding TPO and epoxy boards, characterized in that: The raw materials include the following parts by weight: 10-30 parts of polyolefin elastomer 20-40 parts of synthetic rubber 10-30 parts of modified synthetic rubber 10-30 parts of tackifying resin 10-30 parts softening oil 1-5 parts of crosslinking agent The modified synthetic rubber is a mixture of maleic anhydride-grafted SEBS rubber and epoxy-modified SBS rubber.

2. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 1, characterized in that: The polyolefin elastomer is one or more of ethylene-propylene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer, and the melt index of the polyolefin elastomer at 190°C and 2.16 kg is 2-50 g / 10 min.

3. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 1, characterized in that: The synthetic rubber is one or more of SBS rubber and SEBS rubber.

4. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 1, characterized in that: The mass ratio of the maleic anhydride-grafted SEBS rubber to the epoxy-modified SBS rubber is 1:0.7-1.

5.

5. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 1, characterized in that: The grafting rate of the maleic anhydride-grafted SEBS rubber is 0.5-3%; the epoxy equivalent of the epoxy-modified SBS rubber is 800-2500 g / eq.

6. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 1, characterized in that: The tackifying resin is one or more of petroleum resin and terpene phenol resin.

7. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 6, characterized in that: The softening point of the petroleum resin is 90-120℃; the softening point of the terpene phenol resin is 95-135℃, and the hydroxyl value is 20-50 mg KOH / g.

8. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 1, characterized in that: The softening oil is a naphthenic softening oil.

9. The hot melt adhesive film for bonding TPO and epoxy boards according to claim 1, characterized in that: The crosslinking agent is an amino-terminated isocyanate.

10. A method for preparing a hot melt adhesive film for bonding TPO and epoxy boards according to any one of claims 1-9, characterized in that: Includes the following steps: 1) Weigh the raw materials of each component according to the proportions; 2) Mix the polyolefin elastomer, synthetic rubber, modified synthetic rubber, tackifying resin and softening oil weighed in step 1) evenly and then granulate them using a granulator. 3) After the crosslinking agent weighed in step 1) and the particles obtained in step 2) are mixed evenly, they are fed into a twin-screw extruder and melt-extruded at a certain temperature to form a film.

Images