Thermocuring insulation paste, and preparation method and application thereof

Abstract

The invention provides thermocuring insulating glue as well as a preparation method and application thereof. The viscosity of the thermocuring insulation paste is 15-30 Pa.s, the thixotropic index TI is equal to 2-5, the TI is equal to eta 1 / eta 2, eta 1 is the viscosity of the thermocuring insulation paste at 6 rpm, and eta 2 is the viscosity of the thermocuring insulation paste at 60 rpm; the thermosetting insulating glue comprises the following components in parts by weight: 50-75 parts of epoxy resin, 15-35 parts of filler and 2-5 parts of a curing agent, wherein the viscosity of the epoxy resin at 25 DEG C is 8-80 Pa.s. The invention can solve the problem that the prior art is lack of thermocuring insulating glue which has a proper thixotropic index and is suitable for silk-screen printing.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic materials, and in particular to a heat-curing insulating adhesive, a preparation method and application thereof. Background Art

[0002] Insulating glue for batteries is an ink printed on the grid lines on the back of IBC cells. It is a permanent protective film layer coated on the surface of the grid lines. It acts as an insulating layer to separate the positive and negative electrodes, which can effectively prevent short circuits. Insulating glue can be divided into two types: screen printing type and photosensitive imaging type. Screen printing type has two types: UV curing and thermal curing. UV curing is a fast-curing type with high production efficiency, but photocuring resins and initiators are generally expensive, and a small amount of photoinitiator remaining in the system may have a certain impact on yellowing; thermal curing is relatively cheap, and because the formula has little restriction on the addition of fillers, the pencil hardness of the coating after curing is usually higher than that of photocuring, but the production efficiency of the thermal curing system is relatively low.

[0003] The accuracy of the graphics obtained by screen printing has certain limits. The printing accuracy error range of the insulating glue for batteries is generally required to be within 5%. If you want to print high-quality graphics with high accuracy, you have to have very high requirements on the viscosity and thixotropy of the insulating glue. Summary of the invention

[0004] The main purpose of the present invention is to provide a thermosetting insulating adhesive, a preparation method and application thereof, so as to solve the problem in the prior art of lacking a thermosetting insulating adhesive with a suitable thixotropic index and suitable for screen printing.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a thermosetting insulating adhesive, which has a viscosity of 15 to 30 Pa·s, a thixotropic index TI=2 to 5, TI=η1 / η2, wherein η1 is the viscosity of the thermosetting insulating adhesive at 6rpm, and η2 is the viscosity of the thermosetting insulating adhesive at 60rpm; in parts by weight, the thermosetting insulating adhesive comprises the following components: 50 to 75 parts of epoxy resin, 15 to 35 parts of filler, and 2 to 5 parts of curing agent; wherein the viscosity of the epoxy resin at 25°C is 8 to 80 Pa·s.

[0006] Furthermore, the heat-curing insulating adhesive includes the following components, measured in parts by weight: 60 to 70 parts of epoxy resin, 20 to 30 parts of filler, and 3 to 4 parts of curing agent; wherein the viscosity of the epoxy resin at 25° C. is 10 to 70 Pa·s.

[0007] Furthermore, the heat-curing insulating adhesive further comprises the following components, in parts by weight: 0.1 to 2 parts of defoaming agent, 0.1 to 2 parts of leveling agent, 0.1 to 2 parts of thickener, 1 to 20 parts of solvent, 1 to 10 parts of curing accelerator, and 1 to 10 parts of other additives; other additives include at least one of dispersant, antioxidant, ultraviolet absorber, flame retardant, and adhesion promoter; preferably, the weight ratio of curing accelerator to curing agent is 0.5:1 to 1.25:1.

[0008] Furthermore, the heat-curing insulating adhesive also includes the following components, measured in parts by weight: 0.2 to 1 part of a defoamer, 0.2 to 1 part of a leveling agent, 0.2 to 1 part of a thickener, 2 to 15 parts of a solvent, 2 to 5 parts of a curing accelerator, and 1 to 5 parts of other additives.

[0009] Further, the epoxy resin includes aliphatic glycidyl ether epoxy resin, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, o-cresol epoxy resin, novolac type epoxy resin, phenolic acid varnish type epoxy resin, cresol acid varnish type epoxy resin, N-glycidyl type epoxy resin, bisphenol A novolac type epoxy resin, chelated epoxy resin, glyoxal type epoxy resin, amino-containing epoxy resin One or more of epoxy resin, rubber modified epoxy resin, dicyclopentadiene phenol type epoxy resin, siloxane modified epoxy resin, acrylate modified epoxy resin, e-caprolactone modified epoxy resin; preferably, the epoxy resin includes a first epoxy resin having a viscosity of 10 to 20 Pa·s at 25°C and a second epoxy resin having a viscosity of 40 to 60 Pa·s at 25°C; more preferably, the weight ratio of the first epoxy resin to the second epoxy resin is 1:3 to 3:1.

[0010] Further, the filler includes one or more of barium sulfate, titanium dioxide, talc, bentonite, quartz sand, aluminum oxide, calcium carbonate, glass powder, zinc oxide, and organic pigments; preferably, the filler includes one or more of barium sulfate, talc, and glass powder; preferably, the curing agent includes one or more of dicyandiamide, melamine, anhydride compounds, hydrazide compounds, and boron trifluoride complexes; more preferably, the curing agent includes one or more of dicyandiamide and melamine.

[0011] Further, the defoaming agent includes one or more of BYK-066N, BYK-052, BYK-019, BYK-023, BYK-065, Tech-386N, Tech-3722, KS-66, KSZ-66, Tego-900, and Tego-980; preferably, the defoaming agent includes one or more of BYK-052, KS-66, and Tech-386N; preferably, the leveling agent includes BYK-310, BYK-331, BYK-333, BYK-354, BYK-special, Tech-116, Tech-231, Tech-154N, Tech-2072N, Teg o-420, Tego-100; more preferably, the leveling agent includes one or more of BYK-331 and BYK-special; preferably, the thickener includes one or more of fumed silica A200, fumed silica R974, fumed silica R972, fumed silica R106, BYK-410, BYK-R605, BYK-7410, Tech-9605, and Tech-9010; more preferably, the thickener includes one or more of fumed silica A200, BYK-410, and BYK-R605; preferably, the solvent includes toluene, xylene, acetone, cyclohexanone, ethyl acetate, n-butyl acetate, dipropylene glycol, One or more of glycol methyl ether, ethylene glycol diethyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, dibasic acid ester, tetramethylbenzene, propylene carbonate, isophorone, polymethoxymethyl ether acetate, 3-ethoxyethyl propionate, solvent oil 150#; more preferably, one or more of dibasic acid ester, dipropylene glycol methyl ether, solvent oil 150# The curing accelerator includes 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenyl imidazole; one or more of triphenylphosphine, tertiary amine compounds, quaternary onium salt compounds, and crown ether complexes; preferably, the curing accelerator includes one or more of 2-methylimidazole and 2-ethyl-4-methylimidazole; preferably, the dispersant includes one or more of BYK-190, BYK-180, BYK-110, Tech-597, and Tech-690; more preferably, the dispersant includes one or more of BYK-110 and Tech-597; preferably, the adhesion promoter includes one or more of Tech-7130, Tech-7300, and NEO-8980; more preferably, the adhesion promoter includes one or more of Tech-7130;Preferably, the antioxidant includes one or more of BHT, hindered phenol compounds, and phosphite compounds; more preferably, the antioxidant includes one or more of BHT; preferably, the flame retardant includes one or more of tricresyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, composite phosphorus flame retardant, antimony trioxide, aluminum hydroxide, and magnesium hydroxide; more preferably, the flame retardant includes one or more of tricresyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, and antimony trioxide; preferably, the ultraviolet absorber includes one or more of benzophenone compounds, benzotriazole compounds, and triazine compounds; more preferably, the ultraviolet absorber includes one or more of triazine compounds. ;

[0012] In order to achieve the above object, according to one aspect of the present invention, a method for preparing the above-mentioned heat-curing insulating adhesive is provided, which comprises: weighing epoxy resin, filler, and curing agent in parts by weight, mixing and stirring to obtain heat-curing insulating adhesive.

[0013] Furthermore, epoxy resin, filler, curing agent, defoamer, leveling agent, thickener, solvent, curing accelerator and other optional additives are weighed in parts by weight, mixed and stirred to obtain a heat-curing insulating adhesive.

[0014] According to another aspect of the present invention, an application of the above-mentioned heat-curing insulating adhesive is provided, wherein the heat-curing insulating adhesive is coated on the back grid line of the IBC cell and a protective film layer is formed through a heat-curing reaction.

[0015] By applying the technical solution of the present invention, a thermosetting insulating adhesive for battery cells with suitable viscosity and thixotropy and good printing effect can be provided. The viscosity of the thermosetting insulating adhesive of the present invention is 15-30 Pa·s, and the thixotropy index TI=2-5. When the viscosity is lower than this range, the insulating adhesive is prone to leaking after being poured onto the screen; if it is higher than this range, it is not conducive to fluidity, and the glue is difficult to ink, which affects the effect of screen printing. When the thixotropy index is lower than 2, the fluidity of the insulating adhesive during printing is also small, which is not conducive to uniform ink transfer and inking. At the same time, the printing dots will increase, and the line width of the printed graphics will easily become thicker; if the thixotropy index of the insulating adhesive is greater than 5, the viscosity of the insulating adhesive is relatively high before it becomes thixotropic, which is easy to cause blocking of the screen and paste of the plate during printing, and the printed product is prone to "orange peel" and other phenomena. In the thermosetting insulating adhesive of the present invention, epoxy resin is the main component, which mainly affects the fluidity of the insulating adhesive during screen printing, as well as the basic properties such as hardness and aging resistance after curing. By selecting an epoxy resin with a viscosity of 8 to 80 Pa·s at 25° C. and selecting fillers and curing agents according to the formula of the present invention, the heat-curing insulating adhesive provided by the present invention can be well realized. DETAILED DESCRIPTION

[0016] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0017] In order to solve the problems in the prior art as described above, according to one aspect of the present invention, a heat-curing insulating adhesive is provided. At 25°C, the viscosity of the heat-curing insulating adhesive is 15-30 Pa·s, the thixotropic index TI=2-5, TI=η1 / η2, wherein η1 is the viscosity of the heat-curing insulating adhesive at 6rpm, and η2 is the viscosity of the heat-curing insulating adhesive at 60rpm; the heat-curing insulating adhesive comprises the following components in parts by weight: 50-75 parts of epoxy resin, 15-35 parts of filler, and 2-5 parts of curing agent; wherein the viscosity of the epoxy resin at 25°C is 8-80 Pa·s.

[0018] The viscosity of the thermosetting insulating adhesive of the present invention is 15-30 Pa·s, and the thixotropic index TI=2-5. When the viscosity is lower than this range, the insulating adhesive is prone to leaking after being poured onto the screen; if it is higher than this range, it is not conducive to fluidity, the adhesive is difficult to ink, and the effect of screen printing is affected. When the thixotropic index is lower than 2, the fluidity of the insulating adhesive during printing is also small, which is not conducive to uniform ink transfer and inking. At the same time, the printing dots will increase, and the line width of the printed graphics will easily become thicker; if the thixotropic index of the insulating adhesive is greater than 5, the viscosity of the insulating adhesive is relatively high before the thixotropic property appears, which is easy to cause blocking of the screen and paste of the plate during printing, and the printed product is prone to "orange peel" and other phenomena. In the thermosetting insulating adhesive of the present invention, epoxy resin is the main component, which mainly affects the fluidity of the insulating adhesive during screen printing, as well as the basic properties such as hardness and aging resistance after curing. Selecting an epoxy resin with a viscosity of 8-80 Pa·s at 25°C, and selecting fillers and curing agents according to the formula of the present invention, the thermosetting insulating adhesive provided by the present invention can be well realized.

[0019] Specifically, in the present invention, the adjustment of viscosity and thixotropic index is achieved based on the following mechanism: by adjusting the ratio of resin and filler in the formula, the interaction force between molecules or particles is used to form a network structure, thereby achieving the shear thinning-"thixotropic" effect. It is precisely because of the formula provided by the present invention that a thermosetting insulating adhesive with a designed viscosity and a designed thixotropic index is obtained. Such a thermosetting insulating adhesive has advantages in screen printing and can form a protective film layer with high printing accuracy and good quality.

[0020] It should be noted that the ratio of fillers is also a key parameter for the thermosetting insulating adhesive of the present invention. The inventors found through experiments that the quality of printing will fluctuate significantly with a small change in the filler content. Therefore, the present invention selects the weight of the filler to be 15 to 35 parts. Such a filler ratio can not only play the role of filling and reducing costs, but also will not affect the quality and fineness of printing.

[0021] Unless otherwise specified, the viscosities mentioned in the present invention are values ​​measured at 25°C.

[0022] Unless otherwise specified, the unit of viscosity mentioned in the present invention is Pa·s.

[0023] In the heat-curing insulating adhesive of the present invention, the curing agent is used to cause the heat-curing insulating adhesive system to undergo a cross-linking reaction. Such a cross-linking reaction usually occurs during the application process. During the heat curing process, the epoxy groups in the epoxy resin undergo a ring-opening reaction under the action of the curing agent to form a cross-linked structure.

[0024] In the heat-curing insulating adhesive of the present invention, the defoaming agent plays a role in eliminating bubbles in the insulating adhesive formula; the leveling agent plays a role in adjusting the surface tension of the paint film after screen printing of the insulating adhesive.

[0025] In a preferred embodiment, the heat-curing insulating adhesive comprises the following components by weight: 60-70 parts of epoxy resin, 20-30 parts of filler, and 3-4 parts of curing agent; wherein the viscosity of the epoxy resin at 25° C. is 10-70 Pa·s. The heat-curing insulating adhesive provided by such a formula has better viscosity and thixotropic index.

[0026] In a preferred embodiment, the heat-curing insulating adhesive further comprises the following components by weight: 0.1-2 parts of defoamer, 0.1-2 parts of leveling agent, 0.1-2 parts of thickener, 1-20 parts of solvent, 1-10 parts of curing accelerator, and 1-10 parts of other additives; other additives include at least one of dispersant, antioxidant, ultraviolet absorber, flame retardant, rheological additive, and adhesion promoter. Preferably, the weight ratio of curing accelerator to curing agent is 0.5:1-1.25:1. The curing accelerator can accelerate the curing speed of the heat-curing insulating adhesive, and other additives can further provide the comprehensive performance of the heat-curing insulating adhesive. For example, the dispersant can prevent the sedimentation of the filler, the antioxidant can provide the aging resistance of the coating after the insulating adhesive is cured, the ultraviolet absorber can improve the yellowing resistance of the coating after the insulating adhesive is cured, the flame retardant can improve the flame retardant performance, the rheological additive can further adjust the thixotropy of the insulating adhesive, and the adhesion promoter can improve the adhesion between the insulating adhesive and the substrate.

[0027] In addition, the ratio of the thickener is also a key parameter for the thermosetting insulating adhesive of the present invention, and the amount of the thickener used will significantly affect the thixotropic index of the formula. In the present invention, the weight portion of the thickener is set to 0.1 to 2 parts, and such a ratio can ensure that the formula has good thixotropy, so that the insulating adhesive can form a protective film layer with high printing accuracy and good quality during screen printing.

[0028] In addition, the ratio of defoaming agent to leveling agent is also an important parameter for printing thermosetting insulating adhesive. In the present invention, the weight proportion of the defoaming agent is set to 0.1-2 parts, and the weight proportion of the leveling agent is set to 0.1-2 parts. Such a ratio can better eliminate bubbles in the insulating adhesive formula and adjust the surface tension of the insulating adhesive, so that the pattern after the insulating adhesive is printed has a good appearance.

[0029] In a preferred embodiment, the heat-curing insulating adhesive further comprises the following components by weight: 0.2-1 part of defoamer, 0.2-1 part of leveling agent, 0.2-1 part of thickener, 2-15 parts of solvent, 2-5 parts of curing accelerator, and 2-5 parts of other additives. The above weight ratios can better provide the corresponding effects without causing obvious negative effects, such as decreased aging resistance after curing.

[0030] In practical applications, the amount of the solvent may be further preferably 2 to 10 parts. The inventors have found through experiments that in the heat-curing insulating adhesive of the present invention, when the amount of the solvent is limited to the above range, it is more conducive to obtaining a heat-curing insulating adhesive with suitable viscosity and thixotropic index.

[0031] In a preferred embodiment, the epoxy resin includes one or more of aliphatic glycidyl ether epoxy resin, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, phenolic acid varnish type epoxy resin, cresol acid varnish type epoxy resin, N-glycidyl type epoxy resin, novolac type epoxy resin of bisphenol A, chelate type epoxy resin, glyoxal type epoxy resin, amino-containing epoxy resin, rubber modified epoxy resin, dicyclopentadiene phenol type epoxy resin, siloxane modified epoxy resin, acrylate modified epoxy resin, e-caprolactone modified epoxy resin. These epoxy resins have good insulating properties and are therefore more suitable as the main material of the thermosetting insulating adhesive.

[0032] In a preferred embodiment, the epoxy resin includes a first epoxy resin having a viscosity of 10 to 20 Pa·s at 25° C. and a second epoxy resin having a viscosity of 40 to 60 Pa·s at 25° C.; more preferably, the weight ratio of the first epoxy resin to the second epoxy resin is 1:3 to 3:1. In practical applications, compounding and using a plurality of epoxy resins in this way is more conducive to adjusting the viscosity of the thermosetting insulating adhesive.

[0033] In a preferred embodiment, the epoxy resin is preferably a combination of a linear epoxy resin and a nonlinear epoxy resin. The heat-curing insulating adhesive obtained by such compounding has better performance during heat curing.

[0034] In a preferred embodiment, the filler includes one or more of barium sulfate, titanium dioxide, talc, bentonite, quartz sand, aluminum oxide, calcium carbonate, glass powder, zinc oxide, and organic pigments; preferably, the filler includes one or more of barium sulfate, talc, and glass powder; preferably, the curing agent includes one or more of dicyandiamide, melamine, anhydride compounds, hydrazide compounds, and boron trifluoride complexes; more preferably, the curing agent includes one or more of dicyandiamide and melamine; preferably, the defoaming agent includes BYK-066N, BYK-052, BYK-0 19, BYK-023, BYK-065, Tech-386N, Tech-3722, KS-66, KSZ-66, Tego-900, Tego-980; more preferably, the defoaming agent includes one or more of BYK-052, KS-66, Tech-386N; preferably, the leveling agent includes BYK-310, BYK-331, BYK-333, BYK-354, BYK-special, Tech-116, Tech-231, Tech-1 54N, Tech-2072N, Tego-420, Tego-100; more preferably, the leveling agent includes one or more of BYK-331 and BYK-special; preferably, the thickener includes one or more of fumed silica A200, fumed silica R974, fumed silica R972, fumed silica R106, BYK-410, BYK-R605, BYK-7410, Tech-9605, Tech-9010; more preferably, the thickener includes fumed silica One or more of silica A200, BYK-410, BYK-R605; preferably, the solvent includes one or more of toluene, xylene, acetone, cyclohexanone, ethyl acetate, n-butyl acetate, dipropylene glycol methyl ether, ethylene glycol diethyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, dibasic acid ester, tetramethylbenzene, propylene carbonate, isophorone, polymethoxymethyl ether acetate, 3-ethoxyethyl propionate, solvent oil 150#; more preferably, one or more of dibasic acid ester, dipropylene glycol methyl ether, solvent oil 150#. Selecting the above specific component types is more conducive to obtaining a heat-curing insulating adhesive with good comprehensive performance.

[0035] In order to further improve the comprehensive performance of the heat-curing insulating adhesive, in a preferred embodiment, the curing accelerator includes one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, triphenylphosphine, tertiary amine compounds, quaternary onium salt compounds, and crown ether complexes; preferably, the curing accelerator includes one or more of 2-methylimidazole and 2-ethyl-4-methylimidazole; preferably, the dispersant includes one or more of BYK-190, BYK-180, BYK-110, Tech-597, and Tech-690; more preferably, the dispersant includes one or more of BYK-110 and Tech-597; preferably, The adhesion promoter includes one or more of Tech-7130, Tech-7300, and NEO-8980; more preferably, the adhesion promoter includes one or more of Tech-7130 and NEO-8980; preferably, the antioxidant includes one or more of BHT, hindered phenol compounds, and phosphite compounds; more preferably, the antioxidant includes one or more of BHT; preferably, the flame retardant includes one or more of tricresyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, composite phosphorus flame retardant, antimony trioxide, aluminum hydroxide, and magnesium hydroxide; more preferably, the flame retardant includes one or more of tricresyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, and antimony trioxide; preferably, the ultraviolet absorber includes one or more of benzophenone compounds, benzotriazole compounds, and triazine compounds. More preferably, the ultraviolet absorber includes one or more of triazine compounds.

[0036] According to another aspect of the present invention, a method for preparing the above-mentioned heat-curing insulating adhesive is provided, which comprises: weighing epoxy resin, filler, curing agent, defoaming agent, leveling agent and solvent in parts by weight, mixing and stirring to obtain heat-curing insulating adhesive. The obtained heat-curing insulating adhesive has suitable viscosity and thixotropic index.

[0037] In a preferred embodiment, such a preparation method comprises: weighing epoxy resin, filler, curing agent, defoamer, leveling agent, solvent, curing accelerator and other optional additives in parts by weight, mixing and stirring to obtain a heat-curing insulating adhesive. The heat-curing insulating adhesive prepared in this way has better comprehensive properties.

[0038] In actual operation, the stirring time may be 5 to 20 minutes, for example, 5 minutes, 10 minutes, 15 minutes, or 20 minutes, so as to mix the above components as evenly as possible.

[0039] According to another aspect of the present invention, an application of the above-mentioned heat-curing insulating adhesive is provided, that is, the heat-curing insulating adhesive is applied to the back grid line of the IBC cell, and a protective film layer is formed through a heat curing reaction. The heat-curing insulating adhesive provided by the present invention is very suitable for application in the photovoltaic industry and has good market prospects.

[0040] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0041] Example 1

[0042] Weigh 30.0 g of epoxy resin (Starley GF008 o-cresol epoxy resin, viscosity 46 Pa·s) and 30.0 g of epoxy resin (Starley S0001 bisphenol A epoxy resin, viscosity 14 Pa·s), 21.0 g of barium sulfate, 2.7 g of dicyandiamide, 1.0 g of defoamer BYK-052, 0.5 g of leveling agent BYK-331, 1.0 g of fumed silica A200, 2.0 g of dibasic acid ester, and 3.0 g of 2-methylimidazole; stir under mechanical stirring for 5 min to obtain a heat-curing insulating adhesive sample.

[0043] Example 2

[0044] The difference from Example 1 is that the weight of the fumed silica A200 is 1.8 g and the stirring time is 5 min.

[0045] Example 3

[0046] The difference from Example 2 is that the composition of the epoxy resin is: 30.0 g of epoxy resin (Starley GF008 o-cresol epoxy resin, viscosity 46 Pa·s) and 30.0 g of epoxy resin (Songda SD1159T acrylate modified epoxy resin, viscosity 12 Pa·s).

[0047] Example 4

[0048] The difference from Example 3 is that 0.18 g of BYK-R605 was added.

[0049] Example 5

[0050] The difference from Example 1 is that only 75.0 g of one epoxy resin (Nan Ya NPEL-127 bisphenol A epoxy resin, viscosity 8 Pa·s) is used.

[0051] Example 6

[0052] The difference from Example 1 is that only 50.0 g of one epoxy resin (Bai Chen 634 bisphenol A epoxy resin, viscosity 80 Pa·s) is used.

[0053] Example 7

[0054] The difference from Example 1 is that no curing accelerator is used.

[0055] Example 8

[0056] The difference from Example 1 is that the filler is only talcum powder, and the amount used is 35.0 g.

[0057] Example 9

[0058] The difference from Example 1 is that the solvent is dipropylene glycol methyl ether, and the amount used is 20.0 g.

[0059] Example 10

[0060] The difference from Example 1 is that 1.0 g of a dispersant (Tech-597), 0.5 g of an antioxidant (BHT), 1.0 g of an ultraviolet absorber (UV400, a triazine compound), and 1.0 g of an adhesion promoter (Tech-7130) are additionally added.

[0061] Comparative Example 1

[0062] Weigh 30.0 g of epoxy resin (Starley GF008, viscosity 46 Pa·s) and 30.0 g of epoxy resin (Starley S0001, viscosity 14 Pa·s), 21.0 g of barium sulfate, 2.7 g of dicyandiamide, 1.0 g of defoamer BYK-052, 0.5 g of leveling agent BYK-331, 2.0 g of dibasic acid ester, and 3.0 g of 2-methylimidazole, stir under mechanical stirring for 5 min to obtain a heat-curing insulating adhesive sample.

[0063] Comparative Example 2

[0064] Weigh 30.0 g of epoxy resin (Starley GF008, viscosity 46 Pa·s) and 30.0 g of epoxy resin (Starley S0001, viscosity 14 Pa·s), 21.0 g of barium sulfate, 2.7 g of dicyandiamide, 1.0 g of defoamer BYK-052, 0.5 g of leveling agent BYK-331, 3.0 g of fumed silica A200, 2.0 g of dibasic acid ester, and 3.0 g of 2-methylimidazole, stir under mechanical stirring for 5 min to obtain a heat-curing insulating adhesive sample.

[0065] Comparative Example 3

[0066] Weigh 30.0 g of epoxy resin (Starley GF008, viscosity 46 Pa·s) and 30.0 g of epoxy resin (Starley S0001, viscosity 14 Pa·s), 21.0 g of barium sulfate, 2.7 g of dicyandiamide, 1.0 g of defoamer BYK-052, 0.5 g of leveling agent BYK-331, 1.0 g of fumed silica A200, 30.0 g of dibasic acid ester, and 3.0 g of 2-methylimidazole, stir under mechanical stirring for 5 min to obtain a heat-curing insulating adhesive sample.

[0067] Comparative Example 4

[0068] Weigh 30 g of epoxy resin (Starley GF008, viscosity 46 Pa·s) and 30.0 g of epoxy resin (Starley S0001, viscosity 14 Pa·s), 45.0 g of barium sulfate, 2.7 g of dicyandiamide, 1.0 g of defoamer BYK-052, 0.5 g of leveling agent BYK-331, 1.0 g of fumed silica A200, 2.0 g of dibasic acid ester, and 3.0 g of 2-methylimidazole, stir under mechanical stirring for 5 min to obtain a heat-curing insulating adhesive sample.

[0069] Test method:

[0070] 1. Viscosity test: Use a rotational viscometer to test at a temperature of (24±1)℃ and a relative humidity of (50±5)%. Prepare a cup of insulating glue sample to be tested, and wait until the sample temperature stabilizes to the same as room temperature before testing. According to the level bubble on the body of the rotational viscometer, adjust the machine to keep it horizontal. According to the approximate range of the viscosity of the insulating glue sample and the range of the rotor, select a suitable type of rotor and install it on the main shaft of the rotational viscometer. Adjust the up and down knobs of the rotational viscometer to slowly immerse the rotor into the insulating glue sample to be tested. The immersion depth should be operated according to the requirements of the viscometer manual. Set the rotor speed to 62.5rpm, and read the last stable viscosity value on the instrument display as the viscosity of the insulating glue.

[0071] 2. TI value test: Set the rotor speed to 6rpm, and read the last stable viscosity value on the instrument display as the viscosity η1 (6rpm) at 6rpm. Set the rotor speed to 60rpm, and read the last stable viscosity value on the instrument display as the viscosity η2 (60rpm) at 60rpm.

[0072] The calculation formula of thixotropic index TI is:

[0073]

[0074] The test results are shown in Table 1.

[0075] Table 1

[0076] Viscosity / Pa·s TI value Screen printing effect Example 1 21.0 3.23 Good silk screen printing effect Example 2 27.3 3.73 Good silk screen printing effect Example 3 26.5 3.65 Good silk screen printing effect Example 4 28.6 4.12 Good silk screen printing effect Example 5 16.0 2.70 Good silk screen printing effect Example 6 29.5 3.10 Good silk screen printing effect Example 7 24.5 3.30 Good silk screen printing effect Example 8 25.5 3.50 Good silk screen printing effect Example 9 15.5 2.55 Good silk screen printing effect Example 10 18.9 2.89 Good silk screen printing effect Comparative Example 1 12.0 1.54 Thicker line width Comparative Example 2 37.6 6.35 Screen blocking, board sticking, poor screen printing Comparative Example 3 10.6 1.42 Thicker line width Comparative Example 4 41.2 5.85 Screen blocking, board sticking, poor screen printing

[0077] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0078] The thermosetting insulating adhesive of the invention has a viscosity between 15 and 30 Pa·s, a thixotropic index between 2 and 5, has a good printing effect during screen printing, and is suitable for application in the photovoltaic industry.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A heat-curing insulating adhesive, characterized in that: At 25° C., the viscosity of the heat-curing insulating adhesive is 15 to 30 Pa·s, the thixotropic index TI=2 to 5, and the TI=η1 / η2, wherein η1 is the viscosity of the heat-curing insulating adhesive at 6 rpm, and η2 is the viscosity of the heat-curing insulating adhesive at 60 rpm; The heat-curing insulating adhesive comprises the following components in parts by weight: 50 to 75 parts of epoxy resin, 15 to 35 parts of filler, and 2 to 5 parts of curing agent; wherein the viscosity of the epoxy resin at 25° C. is 8 to 80 Pa·s.

2. The heat-curing insulating adhesive according to claim 1, characterized in that: The heat-curing insulating adhesive comprises the following components in parts by weight: 60 to 70 parts of the epoxy resin, 20 to 30 parts of the filler, and 3 to 4 parts of the curing agent; wherein the viscosity of the epoxy resin at 25° C. is 10 to 70 Pa·s.

3. The heat-curing insulating adhesive according to claim 1, characterized in that: The heat-curing insulating adhesive further comprises the following components in parts by weight: 0.1 to 2 parts of defoaming agent, 0.1 to 2 parts of leveling agent, 0.1 to 2 parts of thickener, 1 to 20 parts of solvent, 1 to 10 parts of curing accelerator, and 1 to 10 parts of other additives; the other additives include at least one of a dispersant, an antioxidant, an ultraviolet absorber, a flame retardant, and an adhesion promoter; Preferably, the weight ratio of the curing accelerator to the curing agent is 0.5:1 to 1.25:

1.

4. The heat-curing insulating adhesive according to claim 3, characterized in that: The heat-curing insulating adhesive further comprises the following components in parts by weight: 0.2 to 1 part of the defoamer, 0.2 to 1 part of the leveling agent, 0.2 to 1 part of the thickener, 2 to 15 parts of the solvent, 2 to 5 parts of the curing accelerator, and 1 to 5 parts of other additives.

5. The heat-curing insulating adhesive according to claim 1 or 2, characterized in that: The epoxy resin includes one or more of aliphatic glycidyl ether epoxy resin, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol F type epoxy resin, o-cresol epoxy resin, novolac type epoxy resin, phenolic acid varnish type epoxy resin, cresol acid varnish type epoxy resin, N-glycidyl type epoxy resin, bisphenol A novolac type epoxy resin, chelate type epoxy resin, glyoxal type epoxy resin, amino-containing epoxy resin, rubber modified epoxy resin, dicyclopentadiene phenol type epoxy resin, siloxane modified epoxy resin, acrylate modified epoxy resin, e-caprolactone modified epoxy resin; Preferably, the epoxy resin includes a first epoxy resin having a viscosity of 10 to 20 Pa·s at 25°C and a second epoxy resin having a viscosity of 40 to 60 Pa·s at 25°C; more preferably, a weight ratio of the first epoxy resin to the second epoxy resin is 1:3 to 3:

1.

6. The heat-curing insulating adhesive according to claim 1 or 2, characterized in that: The filler includes one or more of barium sulfate, titanium dioxide, talc, bentonite, quartz sand, aluminum oxide, calcium carbonate, glass powder, zinc oxide, and organic pigments; preferably, the filler includes one or more of barium sulfate, talc, and glass powder; Preferably, the curing agent includes one or more of dicyandiamide, melamine, anhydride compounds, hydrazide compounds, and boron trifluoride complexes; more preferably, the curing agent includes one or more of dicyandiamide and melamine.

7. The heat-curing insulating adhesive according to claim 3 or 4, characterized in that: The defoaming agent includes one or more of BYK-066N, BYK-052, BYK-019, BYK-023, BYK-065, Tech-386N, Tech-3722, KS-66, KSZ-66, Tego-900, and Tego-980; preferably, the defoaming agent includes one or more of BYK-052, KS-66, and Tech-386N; Preferably, the leveling agent includes one or more of BYK-310, BYK-331, BYK-333, BYK-354, BYK-special, Tech-116, Tech-231, Tech-154N, Tech-2072N, Tego-420, and Tego-100; more preferably, the leveling agent includes one or more of BYK-331 and BYK-special; Preferably, the thickener comprises one or more of fumed silica A200, fumed silica R974, fumed silica R972, fumed silica R106, BYK-410, BYK-R605, BYK-7410, Tech-9605, and Tech-9010; more preferably, the thickener comprises one or more of fumed silica A200, BYK-410, and BYK-R605; Preferably, the solvent includes one or more of toluene, xylene, acetone, cyclohexanone, ethyl acetate, n-butyl acetate, dipropylene glycol methyl ether, ethylene glycol diethyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, dibasic acid ester, tetramethylbenzene, propylene carbonate, isophorone, polymethoxymethyl ether acetate, ethyl 3-ethoxypropionate, and solvent oil 150#; more preferably, one or more of dibasic acid ester, dipropylene glycol methyl ether, and solvent oil 150#; The curing accelerator includes one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, triphenylphosphine, tertiary amine compounds, quaternary onium salt compounds, and crown ether complexes; preferably, the curing accelerator includes one or more of 2-methylimidazole and 2-ethyl-4-methylimidazole; Preferably, the dispersant includes one or more of BYK-190, BYK-180, BYK-110, Tech-597, and Tech-690; More preferably, the dispersant includes one or more of BYK-110 and Tech-597; Preferably, the adhesion promoter includes one or more of Tech-7130, Tech-7300, and NEO-8980; More preferably, the adhesion promoter includes one or more of Tech-7130; Preferably, the antioxidant includes one or more of BHT, hindered phenol compounds, and phosphite compounds; more preferably, the antioxidant includes one or more of BHT; Preferably, the flame retardant includes one or more of tricresyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, composite phosphorus flame retardant, antimony trioxide, aluminum hydroxide, and magnesium hydroxide; More preferably, the flame retardant includes one or more of tricresyl phosphate, triphenyl phosphite, dimethyl methylphosphonate, and antimony trioxide; Preferably, the ultraviolet absorber includes one or more of benzophenone compounds, benzotriazole compounds and triazine compounds; more preferably, the ultraviolet absorber includes one or more of triazine compounds.

8. A method for preparing the heat-curing insulating adhesive according to any one of claims 1 to 7, characterized in that: include: The epoxy resin, filler and curing agent are weighed in parts by weight, mixed and stirred to obtain the heat-curing insulating adhesive.

9. The method for preparing the heat-curing insulating adhesive according to claim 8, characterized in that: include: The epoxy resin, filler, curing agent, defoamer, leveling agent, thickener, solvent, curing accelerator and other optional additives are weighed in parts by weight, mixed and stirred to obtain the heat-curing insulating adhesive.

10. Use of the heat-curing insulating adhesive according to any one of claims 1 to 7, characterized in that: The heat-curing insulating adhesive is coated on the back grid line of the IBC cell sheet, and undergoes a heat-curing reaction to form a protective film layer.

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