Heat-curable pressure-sensitive adhesive composition, adhesive film and preparation method of adhesive film

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to a heat-curable pressure-sensitive adhesive composition, an adhesive film and a preparation method of the adhesive film. The heat-curable pressure-sensitive adhesive composition is prepared from the following components in parts by weight: 25 to 100 parts of acrylic polymer, 25 to 75 parts of epoxy resin, 1 to 10 parts of epoxy curing agent, 1 to 5 parts of accelerant and 0.1 to 1 part of coupling agent. The composition disclosed by the invention is coated on release paper / a release film to obtain a heat-curable pressure-sensitive adhesive film, and the heat-curable pressure-sensitive adhesive composition adhesive film prepared by the method disclosed by the invention has initial viscosity, is suitable for positioning a bonded object, and has relatively high bonding strength after being heated and cured.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a thermosetting pressure-sensitive adhesive composition, an adhesive film, and a method for preparing the same. Background Technology

[0002] Currently, thermosetting pressure-sensitive adhesives are used to bond automotive glass substrates to automotive components. Because various external forces act on the bonded components across a wide temperature range, from low to high temperatures, the adhesive is required to maintain a high level of adhesion across this wide temperature range. Furthermore, if the adhesive is forced to extrude outside the component during bonding, it may hinder subsequent manufacturing steps. Summary of the Invention

[0003] To address the shortcomings of the prior art, this invention provides a heat-curable pressure-sensitive adhesive composition, an adhesive film, and a method for preparing the same. The composition is coated onto release paper / film to obtain a heat-curable pressure-sensitive adhesive film. The heat-curable pressure-sensitive adhesive film has initial tack and low flowability, making it suitable for positioning adhesives. After curing by heating, it exhibits high adhesive strength.

[0004] The specific technical solution is as follows: The first objective of this invention is to provide a thermosetting pressure-sensitive adhesive composition comprising, by weight, the following components: 25-100 parts of acrylate polymer, 25-75 parts of epoxy resin, 1-10 parts of epoxy curing agent, 1-5 parts of accelerator, and 0.1-1 parts of coupling agent.

[0005] Furthermore, the acrylate polymer, by weight, comprises the following components: 50-80 parts of methyl acrylate 5-25 parts of butyl acrylate 5-25 parts of glycidyl methacrylate.

[0006] Furthermore, the Tg of the acrylate polymer is ≤0℃.

[0007] Furthermore, the epoxy resin is one or a mixture of several of the following: bisphenol A type, bisphenol F type, glycidylamine type, alicyclic and phenolic epoxy resins.

[0008] Furthermore, the epoxy equivalent of the epoxy resin is 100-1000 g / eq.

[0009] Furthermore, the epoxy curing agent is one or a mixture of several of the following: modified imidazole and its derivatives, dicyandiamide, acylhydrazine, and acid anhydride.

[0010] Furthermore, the accelerator is one or a mixture of several of modified imidazole, substituted urea, and triazine.

[0011] A second objective of the present invention is to provide a thermosetting pressure-sensitive adhesive composition film, which is prepared by the thermosetting pressure-sensitive adhesive composition as described above.

[0012] A third objective of this invention is to provide a method for preparing the thermosetting pressure-sensitive adhesive film as described above, comprising the following steps: (1) Polymerize an acrylate polymer solution with a solid content of 30-40% according to the component ratios described above; (2) Add epoxy resin, epoxy curing agent, accelerator and coupling agent to acrylate polymer solution in proportion, stir and mix evenly, coat on release paper, dry in drying tunnel, and roll up to obtain the finished product, namely the thermocurable pressure sensitive adhesive composition film.

[0013] Furthermore, in step (2), the temperature of the drying tunnel is set to 60-80℃.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By controlling the Tg of the acrylate polymer to ≤0℃ and the tackifying effect of the epoxy resin, the adhesive film has initial tack at room temperature, which is suitable for positioning with the object to be adhered. (2) The present invention adds a specific amount (5 to 25 parts by weight) of glycidyl methacrylate monomer with epoxy group to the components of acrylate polymer, so that the acrylate polymer can be cured synergistically with epoxy resin, increasing the final curing strength of the adhesive film and ensuring the reliability of the bonding of the object under harsh environment. (3) The present invention uses a precise ratio of epoxy curing agent and accelerator to make the film maintain long-term storage stability at temperatures below 5°C. Detailed Implementation

[0015] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0016] Example 1 A method for preparing a thermosetting pressure-sensitive adhesive film includes the following steps: (1) Preparation of acrylate polymers: The acrylate polymer, by weight, comprises the following components: 80 parts methyl acrylate, 15 parts butyl acrylate, and 5 parts glycidyl methacrylate. Using ethyl acetate as the reaction solvent and azobisisovalerate VAZO-67 as the reaction initiator, the polymerization reaction was carried out at 60℃ for 24 hours to obtain the acrylate polymer PM-01 with a solid content of 30%. (2) Preparation of pressure-sensitive adhesive film: Weigh the following parts by weight: 166.67 parts of PM-01 prepared in step (1) (solid content 30%, actual content is 50 parts), 50 parts of bisphenol type Epikote 828 EL epoxy resin produced by Henssen, Netherlands, 8 parts of epoxy curing agent dicyandiamide produced by AlzChem Dyhard 100S produced by Azken, Germany, 2 parts of substituted urea Dyhard® UR200 produced by Azken, Germany, and 1 part of coupling agent KH-560. Mix them evenly, coat them on release paper, the dry adhesive thickness is 500μm, dry them in the drying tunnel, the temperature of the drying tunnel is set to 60~80℃, dry for 3~5min and then roll them up to get the finished product, that is, the thermosetting pressure-sensitive adhesive composition film.

[0017] Example 2 A method for preparing a heat-curable pressure-sensitive adhesive film, referring to Example 1, the difference from Example 1 is that the PM-01 333.33 parts prepared in step (1) have a solid content of 30% and an actual content of 100 parts.

[0018] Example 3 A method for preparing a thermocurable pressure-sensitive adhesive film, referring to Example 1, the difference from Example 1 is that the PM-01 prepared in step (1) is 83.34 parts (solid content 30%, actual content is 25 parts).

[0019] Example 4 A method for preparing a thermosetting pressure-sensitive adhesive film, referring to Example 1, differs from Example 1 in that 40 parts of bisphenol type Epikote 828 EL produced by Lanhansen and 10 parts of solid epoxy resin DER 663UE produced by Dow Chemical are used.

[0020] Example 5 A method for preparing a heat-curable pressure-sensitive adhesive film, referring to Example 1, differs from Example 1 in that the epoxy curing agent is replaced with hydrazide instead of dicyandiamide.

[0021] Example 6 A method for preparing a thermosetting pressure-sensitive adhesive film, referring to Example 1, differs from Example 1 in that the accelerator is replaced with 2-ethyl-4-methylimidazolium instead of urea.

[0022] Example 7 A method for preparing a thermosetting pressure-sensitive adhesive film, referring to Example 1, except that the dry adhesive thickness is 20 μm.

[0023] Comparative Example 1 A method for preparing a pressure-sensitive adhesive composition film includes the following steps: Weigh the following components by weight: 50 parts of nitrile rubber (NBR40), 50 parts of bisphenol-type Epikote 828 EL epoxy resin (Hanssen, Netherlands), 8 parts of dicyandiamide epoxy curing agent (AlzChem Dyhard 100S, Germany), 2 parts of substituted urea Dyhard® UR200 accelerator (AlzChem, Germany), and 1 part of coupling agent KH-560. Mix thoroughly, coat onto release paper to a dry adhesive thickness of 500 μm, dry in a drying tunnel at a temperature of 60–80 °C for 3–5 minutes, and then wind up to obtain the finished product, i.e., the pressure-sensitive adhesive composition film.

[0024] Comparative Example 2 A method for preparing a pressure-sensitive adhesive composition film, referring to Example 1, differs from Example 1 in that PM-01 is directly coated on release paper, the thickness of the dry adhesive coating is 500μm, and then dried in an oven at a temperature of 60-80℃ for 3-5 minutes to obtain the finished product, namely the pressure-sensitive adhesive composition film.

[0025] test The films obtained in Examples 1-7 and Comparative Examples 1-2 were tested for various properties using the following methods: 1) The initial peel strength of the thermosetting pressure-sensitive adhesive composition film was tested according to the method described in national standard GB / T 2792-2014; 2) Final shear strength test: Apply 4 kg pressure, hot press at 130℃ for 30 min, cool to room temperature and then perform shear strength test according to the method described in national standard GB / T 7124-2008; 3) Final pull-out strength test: Apply 4 kg pressure, hot press at 130℃ for 30 min, and after cooling to room temperature, perform pull-out strength test according to the method described in national standard GB / T33799-2017; 4) High temperature and high humidity aging test after final curing: hot press at 130℃ for 30 minutes with 4 kg pressure, cool to room temperature, and then age at 85℃ and RH85% for 1000 hours before testing the shear strength (double 85 shear strength).

[0026] 5) Thermal shock aging test after final curing: Apply 4 kg pressure, hot press at 130℃ for 30 min, cool to room temperature and then maintain at -40℃ to -85℃ for 30 min per segment. Test the shear strength after 1000 cycles.

[0027] The performance test results of Examples 1-7 and Comparative Examples 1-2 are shown in Table 1.

[0028] Table 1 Performance test data of the films obtained in Examples 1-7 and Comparative Examples 1-2

[0029] As can be seen from the data in Table 1, the initial peel strength of Examples 1-7 is >1 N / 25 mm, which can ensure good positioning of the adhered object. Comparative Example 1, without the addition of pressure-sensitive polymer, has an initial peel strength of 0.01 N / 25 mm and does not have initial positioning performance. The thermosetting adhesive films of Examples 1-7 all have a shear strength >10 MPa after hot pressing and curing, which has good adhesive performance. After environmental reliability aging, the double 85 shear strength and the thermal shock aging shear strength are both >7 MPa, which achieves the adhesive performance of semi-structural adhesives and has long-term adhesive reliability. Comparative Example 2, without the addition of thermosetting epoxy component, has a high peel strength, but its shear strength and pull-out strength are extremely low, resulting in poor adhesive strength and making it unsuitable for bonding structural components.

[0030] In summary, the thermosetting pressure-sensitive adhesive composition film provided by the present invention has good initial tack, is suitable for positioning the object to be bonded, and will not overflow like liquid glue during the thermosetting curing process, thus avoiding contamination and poor adhesion. After thermosetting, the shear strength is >10MPa, which can ensure that the object to be bonded can be used in harsh environments.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermosetting pressure-sensitive adhesive composition, characterized in that, By weight, it comprises the following components: 25-100 parts of acrylate polymer, 25-75 parts of epoxy resin, 1-10 parts of epoxy curing agent, 1-5 parts of accelerator, and 0.1-1 parts of coupling agent.

2. The thermosetting pressure-sensitive adhesive composition according to claim 1, characterized in that, The acrylate polymer comprises, by weight, the following components: 50-80 parts of methyl acrylate 5-25 parts of butyl acrylate 5-25 parts of glycidyl methacrylate.

3. The thermosetting pressure-sensitive adhesive composition according to claim 1 or 2, characterized in that, The acrylate polymer has a Tg ≤ 0℃.

4. The thermosetting pressure-sensitive adhesive composition according to claim 1, characterized in that, The epoxy resin is one or a mixture of several of the following: bisphenol A type, bisphenol F type, glycidylamine type, alicyclic and phenolic epoxy resins.

5. The thermosetting pressure-sensitive adhesive composition according to claim 1 or 4, characterized in that, The epoxy equivalent of the epoxy resin is 100-1000 g / eq.

6. The thermosetting pressure-sensitive adhesive composition according to claim 1, characterized in that, The epoxy curing agent is one or a mixture of several of the following: modified imidazole and its derivatives, dicyandiamide, acylhydrazine, and acid anhydride.

7. The thermosetting pressure-sensitive adhesive composition according to claim 1, characterized in that, The accelerator is one or a mixture of several of the following: modified imidazole, substituted urea, and triazine.

8. A thermosetting pressure-sensitive adhesive composition film, characterized in that, It is prepared by the thermosetting pressure-sensitive adhesive composition as described in any one of claims 2 to 7.

9. A method for preparing a thermosetting pressure-sensitive adhesive film as described in claim 8, characterized in that, Includes the following steps: (1) An acrylate polymer solution with a solid content of 30-40% is polymerized according to the component ratio described in claim 2; (2) Add epoxy resin, epoxy curing agent, accelerator and coupling agent to acrylate polymer solution in proportion, stir and mix evenly, coat on release paper, dry in drying tunnel, and roll up to obtain the finished product, namely the thermocurable pressure sensitive adhesive composition film.

10. The method for preparing the thermosetting pressure-sensitive adhesive film according to claim 9, characterized in that, In step (2), the temperature of the drying tunnel is set to 60-80℃.

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