A fast curing epoxy film and preparation method thereof

Abstract

The present invention relates to the technical field of epoxy film preparation, and specifically to a fast-curing epoxy film and a preparation method thereof. It is characterized in that it is composed of raw materials with the following percentage components: solid epoxy resin, liquid epoxy resin, latent curing agent, toughening agent, cross-linking agent, adhesion promoter, and filler; the toughening agent is a mixture of nitrile rubber modified epoxy resin or polybutadiene rubber modified epoxy resin and polyurethane modified epoxy resin in proportion; the cross-linking agent is amino-terminated isocyanate. The present invention adds amino-terminated isocyanate to pre-cure the epoxy resin with low cross-linking before use, thereby preventing the film from overflowing during heating and curing; the amino-terminated isocyanate can be decomposed at high temperature to obtain isocyanate, and the polyurethane-modified epoxy resin is used as a toughening agent. The decomposed isocyanate can further induce the polyurethane to cross-link, thereby improving the heat resistance of the film.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy film preparation, and in particular to a fast-curing epoxy film and a preparation method thereof. Background Art

[0002] With the rapid development of technologies in aerospace, automobile, electronics and other fields, the demand for high-temperature resistant and high-performance hot melt adhesive films is increasing. Epoxy film, as a thermosetting hot melt adhesive film containing a latent curing agent, is widely used in the bonding of various metal materials, non-metallic materials and composite materials because of its strong bonding performance, good mechanical properties and ability to withstand high temperatures for a long time. Although there are many epoxy film products on the market, the curing time of epoxy film is still generally long, generally more than 30 minutes, which affects production efficiency.

[0003] CN1580171A discloses a heat-curing adhesive film for flexible circuit assembly and its preparation method, which is obtained by coating an adhesive solution formed by epoxy resin, nitrile rubber toughening agent, aromatic amine curing agent, imidazole derivative curing agent and ketone solvent. The bonding strength and toughness are improved by combining multiple epoxy resins, and the curing speed at high temperature is improved by using aromatic polyamine and imidazole derivative composite curing agent, and it can be completely cured within tens of seconds at a temperature of 180°C; wherein:

[0004] The epoxy resin is composed of a mixture of liquid bisphenol A epoxy resin, solid bisphenol A epoxy resin, brominated bisphenol A epoxy resin and novolac epoxy resin;

[0005] The liquid bisphenol A epoxy resin includes E-44 and E-51 epoxy resins, the solid bisphenol A epoxy resin includes E-20 epoxy resin, the brominated bisphenol A epoxy resin includes EX-48 epoxy resin, and the novolac epoxy resin includes F-51 and F-44 epoxy resins.

[0006] CN109679511A discloses a fast-curing adhesive film, comprising a first release layer, an adhesive layer, and a second release layer. The adhesive layer is one of an epoxy adhesive layer, an acrylic adhesive layer, and an organic silicone adhesive layer. The thickness of the adhesive layer is 2-50 μm. The release force ratio of the first release layer to the second release layer is not less than 1:2. The adhesive layer is preferably an epoxy adhesive layer. The weight proportions of the raw materials for preparing the fast-curing adhesive film are as follows: 100 parts of epoxy resin, 10-50 parts of curing agent, 20-100 parts of toughening agent, 1-10 parts of accelerator, 0.5-5 parts of silane coupling agent, 1-10 parts of color paste, and 1-10 parts of matting agent. The invention also discloses a method for preparing the fast-curing adhesive film.

[0007] Although the above-mentioned prior art has improved some properties of the epoxy resin composition, shortened the curing time and improved the curing efficiency, it still has the following disadvantages:

[0008] 1. Epoxy film is mainly toughened with nitrile rubber, which reduces the heat resistance of the film.

[0009] 2. Epoxy films are generally not pre-cured, which makes it easy for the film to overflow during the curing process. Summary of the invention

[0010] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an epoxy film with good heat resistance and fast curing speed and a preparation method thereof. The material can also significantly improve the disadvantage of glue overflow during the use of the film.

[0011] The technical solution adopted by the present invention to solve the above problems is:

[0012] A fast curing epoxy film is composed of raw materials with the following percentage components:

[0013] 10-40 parts of solid epoxy resin;

[0014] 10-40 parts of liquid epoxy resin;

[0015] 2-10 parts of latent curing agent;

[0016] 10-30 parts of toughening agent;

[0017] 1-3 parts of cross-linking agent;

[0018] Adhesion promoter 0.1-0.5 parts;

[0019] 5-20 parts of filler.

[0020] The toughening agent is obtained by mixing nitrile rubber modified epoxy resin or polybutadiene rubber modified epoxy resin and polyurethane modified epoxy resin in a ratio of 1:0.5-1.5; and the cross-linking agent is amino-terminated isocyanate.

[0021] Furthermore, the solid epoxy resin is one or more of bisphenol A epoxy resin and novolac epoxy resin which are solid at room temperature.

[0022] Furthermore, the liquid epoxy resin is one or more of bisphenol A epoxy resin and bisphenol F epoxy resin.

[0023] Furthermore, the latent curing agent is one or more of modified imidazole, dicyandiamide, organic urea, and modified amine.

[0024] Furthermore, the toughening agent is one or more of nitrile rubber modified epoxy resin, polybutadiene rubber modified epoxy resin, and polyurethane modified epoxy resin. The viscosity of the nitrile rubber modified epoxy resin and the polybutadiene rubber modified epoxy resin is 150000-600000 mPa·s, and the EEW value is 260-380 g / eq; further, the viscosity of the polyurethane modified epoxy resin is 7000-30000 CPS, and the epoxy equivalent is 245-650 g / eq. The nitrile rubber modified epoxy resin may be, but not limited to, HyPoxRA840, HyPoxRA1340, and HyPoxRK1340 from CVC of the United States; the polybutadiene rubber modified epoxy resin may be, but not limited to, MX153 and MX158 from KANEKA of Japan; the polyurethane modified epoxy resin may be, but not limited to, EPU-301 and EPU-303 from Shanghai Hehe High-tech, and DER3912 and DER3913 from DOW.

[0025] Furthermore, the crosslinking agent is amino-terminated isocyanate. The preparation method is as follows: adding powdered isocyanate to cyclohexane, adding a certain proportion of polyamine polymer under vigorous stirring, and removing cyclohexane after stirring to obtain white powder.

[0026] Furthermore, the adhesion promoter is 3-aminopropyl triethoxysilane, 3-glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl methyl diethoxysilane, and 3-glycidyloxypropyl methyl dimethoxysilane.

[0027] Furthermore, the filler is one or more of fumed silica, talcum powder, calcium carbonate and zinc oxide.

[0028] A method for preparing a fast curing epoxy film comprises the following steps:

[0029] 1) Weigh the raw materials of each component according to the proportion;

[0030] 2) Add the latent curing agent to the liquid epoxy resin and disperse it for 20 minutes at a stirring speed of 100-1200r / min;

[0031] 3) Put solid epoxy resin, toughening agent, adhesion promoter and filler into a kneading machine, heat to 100°C and knead for 1 hour;

[0032] 4) The kneading machine temperature is lowered to 60° C. The dispersion obtained in step 2) and the crosslinking agent are added into the kneading machine, and the kneading is continued for 10 minutes;

[0033] 5) Using a calender, the rubber material obtained in step 4) is calendered into a rubber film of a certain thickness.

[0034] Compared with the prior art, the present invention has the following characteristics:

[0035] 1. The epoxy film cures within 10 minutes when baked at 150°C, greatly shortening the time required for curing and molding.

[0036] 2. By adding amino-terminated isocyanate, the epoxy resin is pre-cured with low cross-linking before use to prevent the adhesive film from overflowing during heating and curing. The amino-terminated isocyanate used in the present invention can be decomposed to obtain isocyanate at high temperature. If a polyurethane-modified epoxy resin is used as a toughening agent, the decomposed isocyanate can further induce the polyurethane to cross-link, thereby improving the heat resistance of the adhesive film. DETAILED DESCRIPTION

[0037] The content of the present invention is explained below in conjunction with specific embodiments.

[0038] Some of the raw materials used in the examples and comparative examples of the present invention are as follows:

[0039] The solid epoxy resin is preferably one or more of bisphenol A epoxy resin and novolac epoxy resin; wherein, the bisphenol A epoxy resin may be but not limited to CYD-011 and CYD-012 of Yueyang Petrochemical, RER671 of DOW, YD-001S and YD-012 of Guodu Chemical; the novolac epoxy resin may be but not limited to CYDCN-200 and CYDCN-208 of Yueyang Petrochemical, YDCN-500-8P and YDCN-500-10P of Guodu Chemical.

[0040] The liquid epoxy resin may be, but is not limited to, one or more of CYD-128 and CYD-144 of Yueyang Petrochemical, DER331, DER736 and DER791 of DOW.

[0041] The latent curing agent may be, but is not limited to, one or more of AH-154 and MY-24 from Ajinomoto of Japan, EH-4360S from ADEKA of Japan, and Dyhard100S and DyhardUR500 from Alzchem of Germany.

[0042] The toughening agent is preferably one or more of nitrile rubber modified epoxy resin, polybutadiene rubber modified epoxy resin, and polyurethane modified epoxy resin; wherein the nitrile rubber modified epoxy resin may be, but not limited to, HyPoxRA840, HyPoxRA1340, and HyPoxRK1340 of CVC of the United States; the polybutadiene rubber modified epoxy resin may be, but not limited to, MX153 and MX158 of KANEKA of Japan; the polyurethane modified epoxy resin may be, but not limited to, EPU-301 and EPU-303 of Shanghai Hehe High-tech, and DER3912 and DER3913 of DOW.

[0043] The cross-linking agent is preferably an amino-terminated isocyanate, wherein the isocyanate may be but not limited to MetalinkU from DOW, and the end-capping polyamine polymer may be but not limited to D230 and T403 from Huntsman.

[0044] The adhesion promoter may be, but is not limited to, one or more of KH-550, KH-560, SCA-A10E, SCA-A10M, SCA-E87F, and SCA-E87T of Nanjing Nengde New Materials.

[0045] Example 1

[0046] A method for preparing a fast-curing epoxy film, the method comprising the following process steps:

[0047] 1) Weigh 20 parts of bisphenol A epoxy resin CYD-011, 8.5 parts of phenolic epoxy resin CYDCN-208, 30 parts of liquid epoxy resin CYD-128, 5 parts of latent curing agent AH-154, 1.2 parts of latent curing agent DyhardUR500, 10 parts of toughening agent HyPoxRA840, 12 parts of toughening agent EPU-301, 2 parts of crosslinking agent, 0.5 parts of adhesion promoter KH-560, 1 part of fumed silica, and 6 parts of talc according to mass fraction;

[0048] 2) Add the liquid epoxy resin and latent curing agent weighed in step 1) into a mixer and disperse at 800 r / min for 20 min;

[0049] 3) putting the bisphenol A epoxy resin, phenolic epoxy resin, toughening agent, adhesion promoter, fumed silica and talc weighed in step 1) into a kneader, heating to 100° C. and kneading for 1 hour;

[0050] 4) The kneading machine temperature is lowered to 60° C. The dispersion obtained in step 2) and the crosslinking agent are added into the kneading machine, and the kneading is continued for 10 minutes;

[0051] 5) Using a calender, the rubber material obtained in step 4) is calendered into a rubber film of a certain thickness.

[0052] Example 2

[0053] A method for preparing a fast-curing epoxy film, the method comprising the following process steps:

[0054] 1) Weigh 18 parts of bisphenol A epoxy resin CYD-011, 10 parts of phenolic epoxy resin CYDCN-208, 36 parts of liquid epoxy resin CYD-128, 2.5 parts of latent curing agent Dyhard100S, 1.2 parts of latent curing agent DyhardUR500, 14 parts of toughening agent MX153, 8 parts of toughening agent DER3912, 1.6 parts of crosslinking agent, 0.5 parts of adhesion promoter SCA-A10E, 1 part of fumed silica, and 6 parts of talc according to mass fraction;

[0055] 2) Add the liquid epoxy resin and latent curing agent weighed in step 1) into a mixer and disperse at 800 r / min for 20 min;

[0056] 3) putting the bisphenol A epoxy resin, phenolic epoxy resin, toughening agent, adhesion promoter, fumed silica and talc weighed in step 1) into a kneader, heating to 100° C. and kneading for 1 hour;

[0057] 4) The kneading machine temperature is lowered to 60° C. The dispersion obtained in step 2) and the crosslinking agent are added into the kneading machine, and the kneading is continued for 10 minutes;

[0058] 5) Using a calender, the rubber material obtained in step 4) is calendered into a rubber film of a certain thickness.

[0059] Example 3

[0060] A method for preparing a fast-curing epoxy film, the method comprising the following process steps:

[0061] 1) Weigh 20 parts of bisphenol A epoxy resin CYD-011, 10 parts of phenolic epoxy resin CYDCN-208, 26 parts of liquid epoxy resin DER331, 8 parts of liquid epoxy resin RDE791, 2.2 parts of latent curing agent Dyhard100S, 10 parts of toughening agent HyPoxRK1340, 12 parts of toughening agent EPU-301, 1 part of latent curing agent DyhardUR500, 2 parts of crosslinking agent, 0.5 parts of adhesion promoter SCA-E87T, 1 part of fumed silica, and 6 parts of talc according to mass fraction;

[0062] 2) Add the liquid epoxy resin and latent curing agent weighed in step 1) into a mixer and disperse at 800 r / min for 20 min;

[0063] 3) putting the bisphenol A epoxy resin, phenolic epoxy resin, toughening agent, adhesion promoter, fumed silica and talc weighed in step 1) into a kneader, heating to 100° C. and kneading for 1 hour;

[0064] 4) The kneading machine temperature is lowered to 60° C. The dispersion obtained in step 2) and the crosslinking agent are added into the kneading machine, and the kneading is continued for 10 minutes;

[0065] 5) Using a calender, the rubber material obtained in step 4) is calendered into a rubber film of a certain thickness.

[0066] Comparative Example 1

[0067] The process is basically the same as Example 1, except that the latent curing agent Dyhard UR500 is not added.

[0068] Comparative Example 2

[0069] It is basically the same as Example 1, except that 10 parts of toughening agent HyPoxRA840 are used, and 12 parts of toughening agent EPU-301 are changed to 22 parts of toughening agent HyPoxRA840.

[0070] Comparative Example 3

[0071] It is basically the same as Example 1, except that 10 parts of toughening agent HyPoxRA840 are used, and 12 parts of toughening agent EPU-301 are changed to 22 parts of toughening agent MX153.

[0072] Comparative Example 4

[0073] It is basically the same as Example 1, except that 10 parts of toughening agent HyPoxRA840 are used, and 12 parts of toughening agent EPU-301 are changed to 22 parts of toughening agent EPU301.

[0074] Comparative Example 5

[0075] Basically the same as Example 1, except that no cross-linking agent is added.

[0076] The 0.1 mm thick fast curing epoxy film prepared in Examples 1-3 and its final product after complete curing were compared and tested. The experimental results are as follows:

[0077]

[0078] It can be seen from the test results that the epoxy films of Examples 1-3 of the present invention have a fast curing speed, a room temperature shear strength of more than 23 MPa, a 120° C. shear strength of more than 18 MPa, and a significant improvement in the glue overflow.

[0079] The above contents are detailed descriptions of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, various changes or modifications that can be easily thought of to the present invention without departing from the concept of the present invention should be included in the protection scope of the present invention.

Claims

1. A fast curing epoxy film, characterized in that: It is composed of the following raw materials in percentage: 10-40 parts of solid epoxy resin; Liquid epoxy resin 10-40 parts; 2-10 parts of latent curing agent; 10-30 parts of toughening agent; 1-3 parts of cross-linking agent; Adhesion promoter 0.1-0.5 parts; 5-20 parts of filler; The toughening agent is obtained by mixing nitrile rubber modified epoxy resin or polybutadiene rubber modified epoxy resin with polyurethane modified epoxy resin in a ratio of 1:0.5-1.5; the cross-linking agent is amino-terminated isocyanate; The method for preparing the fast curing epoxy film comprises the following steps: 1) Weigh the raw materials of each component according to the proportion; 2) Add the latent curing agent to the liquid epoxy resin and disperse it for 20 minutes at a stirring speed of 100-1200r / min; 3) Put solid epoxy resin, toughening agent, adhesion promoter and filler into a kneading machine, heat to 100°C and knead for 1 hour; 4) The kneading machine temperature is lowered to 60° C. The dispersion obtained in step 2) and the crosslinking agent are added into the kneading machine, and the kneading is continued for 10 minutes; 5) Using a calender, the rubber material obtained in step 4) is calendered into a rubber film of a certain thickness.

2. The fast curing epoxy film according to claim 1, characterized in that: The solid epoxy resin is one or more of bisphenol A epoxy resin and novolac epoxy resin which are solid at room temperature.

3. The fast curing epoxy film according to claim 1, characterized in that: The liquid epoxy resin is one or more of bisphenol A epoxy resin and bisphenol F epoxy resin.

4. The fast curing epoxy film according to claim 1, characterized in that: The latent curing agent is one or more of modified imidazole, dicyandiamide, organic urea and modified amine.

5. The fast curing epoxy film according to claim 1, characterized in that: The viscosity of the nitrile rubber modified epoxy resin and the polybutadiene rubber modified epoxy resin is 150000-600000 mPa·s, and the EEW value is 260-380 g / eq; the polyurethane modified epoxy resin is 7000-30000 CPS, and the epoxy equivalent is 245-650 g / eq.

6. The fast curing epoxy film according to claim 1, characterized in that: The crosslinking agent is amino-terminated isocyanate, and the preparation method is as follows: adding powdered isocyanate into cyclohexane, adding a certain proportion of polyamine polymer under vigorous stirring, and removing cyclohexane after stirring to obtain white powder.

7. The fast curing epoxy film according to claim 1, characterized in that: The adhesion promoter is one or more of 3-aminopropyl triethoxysilane, 3-glycidyloxypropyl trimethoxysilane, 3-glycidyloxypropyl methyl diethoxysilane and 3-glycidyloxypropyl methyl dimethoxysilane.

8. The fast curing epoxy film according to claim 1, characterized in that: The filler is one or more of fumed silica, talcum powder, calcium carbonate and zinc oxide.

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