A bipolar plate frame adhesive and its preparation method and application

Abstract

The present invention discloses a bipolar plate frame adhesive and a preparation method and application thereof. The adhesive is composed of the following raw material components by mass: 16 to 50 parts of diphenylmethane diisocyanate; 20 to 60 parts of polybutylene adipate diol; 12 to 32 parts of Dow 2120 polyether polyol; 10 to 40 parts of epoxy resin; 10 to 20 parts of active diluent; 0.5 to 5 parts of catalyst; 1 to 4 parts of accelerator; 0.5 to 5 parts of photoinitiator; 1 to 5 parts of filler. The adhesive improves the bonding ability, durability, heat resistance and mechanical strength of the adhesive, maintains the bonding force at a relatively low temperature, realizes a solvent-free system, is environmentally friendly and reduces the preparation cost; can be cured by ultraviolet light curing without the need for a hot pressing process, so that it is applied to bipolar plate frame materials such as polypropylene without cracking.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to a bipolar plate frame adhesive and a preparation method and application thereof. Background Art

[0002] Hot melt adhesive is a plastic adhesive. Under certain external conditions, its physical form will change with temperature, but its chemical properties remain unchanged and will not cause environmental pollution. It is an environmentally friendly chemical. Traditional hot melt adhesive is mainly ethylene-vinyl acetate (EVA) hot melt adhesive, which has excellent bonding properties, good flexibility and high and low temperature resistance.

[0003] At present, hot melt adhesive is widely used in the sealing process of battery graphite bipolar plates, and the bipolar plates are sealed and bonded through hot melt film hot press sealing or EPDM rubber pad-hot melt film hot press sealing. However, the current sealing method has high requirements on the mechanical properties of the bipolar plate frame material, and it is difficult to apply to frame materials that are deformed by heat. For example, for bipolar plate frames made of polypropylene material, hot melt adhesive hot press sealing will cause a certain degree of deformation of polypropylene and the hot melt adhesive itself, which will make the bipolar plate prone to cracking. Summary of the invention

[0004] The present invention provides a bipolar plate frame adhesive and a preparation method and application thereof, so as to solve the technical problem that the current hot melt adhesive easily causes the bipolar plate to crack.

[0005] In order to solve the above technical problems, in a first aspect, the present invention provides a bipolar plate frame adhesive, which is composed of the following raw material components in parts by mass:

[0006] 14 to 32 parts of diphenylmethane diisocyanate;

[0007] 20 to 60 parts of polybutylene adipate diol;

[0008] Dow 2120 polyether polyol 15 to 32 parts;

[0009] 10 to 40 parts of epoxy resin;

[0010] 10 to 20 parts of active diluent;

[0011] 0.5 to 5 parts of catalyst;

[0012] 1 to 4 parts of accelerator;

[0013] 0.5 to 5 parts of photoinitiator;

[0014] 1 to 5 parts of filler.

[0015] Preferably, it is composed of the following raw material components in parts by weight:

[0016] 25 parts of diphenylmethane diisocyanate;

[0017] 30 parts of polybutylene adipate diol with a molecular weight of 3000;

[0018] Dow 2120 polyether polyol 22 parts;

[0019] Epoxy resin 20 parts;

[0020] Active diluent 15 parts;

[0021] 3 parts of catalyst;

[0022] 2 parts of accelerator;

[0023] 3.7 parts of photoinitiator;

[0024] 3 parts of filling.

[0025] Furthermore, the epoxy resin is bisphenol A epoxy resin, the active diluent is epoxy active diluent, the accelerator is epoxy accelerator, and the filler is nano filler. The molecular weight of Dow 2120 polyether polyol is 2000 and the hydroxyl value is 56.

[0026] Further preferably, the epoxy resin is at least one of E-51 epoxy resin, E-20 epoxy resin and E-12 epoxy resin, the active diluent is epoxy active diluent 660A, the accelerator is epoxy accelerator DMP-30, and the filler is nano-silicon dioxide.

[0027] Further, the catalyst includes dibutyltin dilaurate and triethylenediamine.

[0028] Further, the photoinitiator is at least one of iodonium salt, sulfonium salt and iron arene. Preferably, the photoinitiator is diphenyliodonium salt or triphenylsulfonium salt.

[0029] In a second aspect, the present invention further provides a method for preparing the bipolar plate frame adhesive as described in the first aspect, comprising the following steps:

[0030] Step 1, in a nitrogen environment, diphenylmethane diisocyanate, dehydrated polybutylene adipate diol and Dow 2120 polyether polyol are uniformly stirred, and then the temperature is raised to 85° C. to 90° C. for reaction until the free NCO group content is 4% to 9%, thereby obtaining a polyurethane prepolymer;

[0031] Step 2: adding epoxy resin, catalyst and active diluent to the polyurethane prepolymer in sequence at a temperature of 70° C. to 75° C., reacting for 2 h to 3 h to obtain an epoxy resin grafted polyurethane component;

[0032] Step three, adding an accelerator and a photoinitiator to the epoxy resin grafted polyurethane component, continuing the reaction for 0.5h to 1h, and then adding a filler and stirring evenly to obtain a bipolar plate adhesive.

[0033] Preferably, the reaction temperature of step 1 is 85° C., and the content of free NCO groups is 5% to 7%.

[0034] Further, epoxy resin, catalyst and active diluent are added to the polyurethane prepolymer in sequence, including:

[0035] Epoxy resin and dibutyltin dilaurate are added to the polyurethane prepolymer for chain extension for 0.5h to 1h, and then triethylenediamine and active diluent are added to continue the reaction.

[0036] In a third aspect, the present invention further provides an application of the bipolar plate frame adhesive obtained by the preparation method described in the second aspect in bonding the bipolar plate frame of a battery.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention uses Dow 2120 polyether polyol as the polyol for synthesizing isocyanate prepolymer to introduce ether bonds to enhance the low-temperature resistance of the adhesive, so that the adhesive can still maintain its adhesion at a relatively low temperature; epoxy resin is grafted onto the isocyanate-terminated polyurethane prepolymer to improve the adhesive ability, durability, heat resistance and mechanical strength of the adhesive; an active diluent is used to adjust the viscosity of the system to achieve a solvent-free system, thereby eliminating the need for post-treatment processes of removing water and solvent, being environmentally friendly and reducing preparation costs; a filler is used to fill and modify the adhesive, so that the mechanical properties and thermal properties of the adhesive are greatly improved and the deformation of the adhesive is reduced; a photoinitiator is used to enable ultraviolet light curing for curing treatment, without the need for a hot pressing process, so that the adhesive is applied to bipolar plate frame materials such as polypropylene without the occurrence of plate cracking. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0040] As used herein, the term "prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0041] When amount, concentration or other value or parameter is expressed as range, preferred range or a series of upper preferred value and lower preferred value limit range, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0042] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention have no restrictions on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the number is obviously intended to be in the singular form.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0044] Example 1

[0045] A bipolar plate frame adhesive is composed of the following raw material components in parts by weight:

[0046] 14 parts of diphenylmethane diisocyanate;

[0047] 20 parts of polybutylene adipate diol (molecular weight 3000);

[0048] Dow 2120 polyether polyol 15 parts;

[0049] 10 parts of E-51 epoxy resin, E-20 epoxy resin and E-12 epoxy resin (mass ratio 1:1:1);

[0050] Epoxy reactive diluent 660A 10 parts;

[0051] 1 part of dibutyltin dilaurate;

[0052] Triethylenediamine 0.5;

[0053] Epoxy accelerator DMP-30 1 part;

[0054] 0.5 parts of diphenyliodonium salt;

[0055] 1 part of nano silicon dioxide.

[0056] The preparation method of the bipolar plate frame adhesive comprises the following steps:

[0057] Step 1, in a nitrogen environment, diphenylmethane diisocyanate, dehydrated polybutylene adipate diol and Dow 2120 polyether polyol are uniformly stirred, and then the temperature is raised to 85° C. to react until the free NCO group content is 5% to 7%, thereby obtaining a polyurethane prepolymer;

[0058] Step 2: adding epoxy resin and dibutyltin dilaurate to the polyurethane prepolymer at a temperature of 70° C. to extend the chain for 0.5 h, and then adding triethylenediamine and a reactive diluent to continue the reaction for 2 h to obtain an epoxy resin grafted polyurethane component;

[0059] Step three, adding an accelerator and a photoinitiator to the epoxy resin grafted polyurethane component, continuing the reaction for 0.5 hours, and then adding a filler and stirring evenly to obtain a bipolar plate adhesive.

[0060] Example 2

[0061] A bipolar plate frame adhesive is composed of the following raw material components in parts by weight:

[0062] 32 parts of diphenylmethane diisocyanate;

[0063] 60 parts of polybutylene adipate diol (molecular weight 3000);

[0064] Dow 2120 polyether polyol 32 parts;

[0065] 40 parts of E-51 epoxy resin, E-20 epoxy resin and E-12 epoxy resin (mass ratio 1:1:1);

[0066] Epoxy reactive diluent 660A 20 parts;

[0067] 3 parts of dibutyltin dilaurate;

[0068] 2 parts of triethylenediamine;

[0069] Epoxy accelerator DMP-30 4 parts;

[0070] 5 parts of triphenylsulfonium salt;

[0071] 5 parts of nano silicon dioxide.

[0072] The preparation method of the bipolar plate frame adhesive comprises the following steps:

[0073] Step 1, in a nitrogen environment, diphenylmethane diisocyanate, dehydrated polybutylene adipate diol and Dow 2120 polyether polyol are uniformly stirred, and then the temperature is raised to 90° C. to react until the free NCO group content is 5% to 7%, thereby obtaining a polyurethane prepolymer;

[0074] Step 2: adding epoxy resin and dibutyltin dilaurate to the polyurethane prepolymer at a temperature of 75° C. to extend the chain for 1 hour, and then adding triethylenediamine and a reactive diluent to continue the reaction for 3 hours to obtain an epoxy resin grafted polyurethane component;

[0075] Step three, adding an accelerator and a photoinitiator to the epoxy resin grafted polyurethane component, continuing the reaction for 1 hour, and then adding a filler and stirring evenly to obtain a bipolar plate adhesive.

[0076] Example 3

[0077] A bipolar plate frame adhesive is composed of the following raw material components in parts by weight:

[0078] 25 parts of diphenylmethane diisocyanate;

[0079] 30 parts of polybutylene adipate diol (molecular weight 3000);

[0080] Dow 2120 polyether polyol 22 parts;

[0081] 20 parts of E-51 epoxy resin, E-20 epoxy resin and E-12 epoxy resin (mass ratio 1:1:1);

[0082] Epoxy reactive diluent 660A 15 parts;

[0083] 2 parts of dibutyltin dilaurate;

[0084] 1 part of triethylenediamine;

[0085] Epoxy accelerator DMP-30 2 parts;

[0086] 3.7 parts of diphenyliodonium salt;

[0087] 3 parts of nano silicon dioxide.

[0088] The preparation method of the bipolar plate frame adhesive comprises the following steps:

[0089] Step 1, in a nitrogen environment, diphenylmethane diisocyanate, dehydrated polybutylene adipate diol and Dow 2120 polyether polyol are uniformly stirred, and then the temperature is raised to 85° C. to react until the free NCO group content is 5% to 7%, thereby obtaining a polyurethane prepolymer;

[0090] Step 2: adding epoxy resin and dibutyltin dilaurate to the polyurethane prepolymer at a temperature of 75° C. to extend the chain for 1 hour, and then adding triethylenediamine and a reactive diluent to continue the reaction for 2 hours to obtain an epoxy resin grafted polyurethane component;

[0091] Step three, adding an accelerator and a photoinitiator to the epoxy resin grafted polyurethane component, continuing the reaction for 0.5 hours, and then adding a filler and stirring evenly to obtain a bipolar plate adhesive.

[0092] Comparative Example 1

[0093] The curing agent T31 was used to replace the photoinitiator, and the rest was the same as in Example 3.

[0094] Comparative Example 2

[0095] The polybutylene adipate diol with an equal molar amount of hydroxyl groups was used to replace Dow 2120 polyether polyol, and the rest was the same as in Example 3.

[0096] Comparative Example 3

[0097] Excessive 1,4-butanediol was used to replace the epoxy resin, and the rest was the same as in Example 3.

[0098] Comparative Example 4

[0099] Acetone was used instead of the active diluent, and the rest was the same as in Example 3.

[0100] Comparative Example 5

[0101] No epoxy accelerator was added, and the rest was the same as in Example 3.

[0102] Comparative Example 6

[0103] No nano silicon dioxide was added, and the rest was the same as in Example 3.

[0104] 1. Performance Testing

[0105] The bipolar plate frame adhesive prepared in Examples 1 to 3 and Comparative Examples 1 to 6 was introduced into a mold for curing, and test samples were made according to the corresponding performance test standards. The tensile shear performance test was carried out according to GB / T 7124-2008, and the impact performance test was carried out according to GB / T1043-2008.

[0106] Adhesion strength test after high temperature and high humidity: glass bonding sample, bonding area 3mm×3mm, UV light power density 80w / cm, illumination distance cm, after curing for 3min (comparative example 1 uses 365mm LED light source for 105℃ curing), put it in 85℃ / 85% humidity environment for 1000 hours, take it out to evaporate the water, cool to room temperature, and use Dage chip thrust machine at a speed of 6mm / min to test the adhesion after high temperature and high humidity.

[0107] Adhesion strength test after high and low temperature cycles: glass bonding sample, bonding area 3mm×3mm, UV light power density 80w / cm, illumination distance cm, after curing for 3min (comparative example 1 uses 365mm LED light source for 105℃ curing for 1h), put it into high and low temperature cycle (-20℃~7o℃, each temperature for 1h, heating and cooling time 30min) environment for 1000 hours, take it out and return to room temperature, use Dage chip thrust machine with a speed of 6mm / min to test the adhesion after high and low temperature cycles.

[0108] Initial bonding strength test: PP frame bonding sample, under UV light power density of 80w / cm, irradiation distance of cm, after curing for 90s, normal curing for 5min, cut into 200mm×8mm strips, and test the peeling strength.

[0109] The test results are shown in the following table.

[0110]

[0111] As can be seen from the above table, Examples 1-3 have better mechanical properties, heat resistance and initial adhesion properties than Comparative Examples 1-6. The present invention uses Dow 2120 polyether polyol as the polyol for synthesizing isocyanate prepolymers to introduce ether bonds to enhance the low temperature resistance of the adhesive, so that it still maintains adhesion at lower temperatures; epoxy resin is grafted on the isocyanate-terminated polyurethane prepolymer to improve the bonding ability, durability, heat resistance and mechanical strength of the adhesive; active diluents are used to adjust the viscosity of the system to achieve a solvent-free system, thereby eliminating the need for post-treatment processes such as water removal and solvent removal, which is environmentally friendly and reduces preparation costs; fillers are used to fill and modify the adhesive, so that the mechanical properties and thermal properties of the adhesive are greatly improved, and the deformation of the adhesive is reduced; photoinitiators are used to enable ultraviolet light curing for curing treatment, without the need for hot pressing processes, so that it can be applied to bipolar plate frame materials such as polypropylene without cracking.

[0112] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A bipolar plate frame adhesive, characterized in that: It is composed of the following raw material components in parts by weight: 14 to 32 parts of diphenylmethane diisocyanate; 20 to 60 parts of polybutylene adipate diol; Dow 2120 polyether polyol 15 to 32 parts; 10 to 40 parts of epoxy resin; 10 to 20 parts of active diluent; 0.5 to 5 parts of catalyst; 1 to 4 parts of accelerator; 0.5 to 5 parts of photoinitiator; 1 to 5 parts of filler; The epoxy resin is at least one of E-51 epoxy resin, E-20 epoxy resin and E-12 epoxy resin, the active diluent is epoxy active diluent 660A, the accelerator is epoxy accelerator DMP-30, the filler is nano-silicon dioxide, and the catalyst includes dibutyltin dilaurate and triethylenediamine; The preparation method of the bipolar plate frame adhesive comprises the following steps: Step 1, in a nitrogen environment, diphenylmethane diisocyanate, dehydrated polybutylene adipate diol and Dow 2120 polyether polyol are uniformly stirred, and then the temperature is raised to 85° C. to react until the free NCO group content is 5% to 7%, thereby obtaining a polyurethane prepolymer; Step 2: adding epoxy resin and dibutyltin dilaurate to the polyurethane prepolymer at a temperature of 70° C. to 75° C. to extend the chain for 0.5 h to 1 h, and then adding triethylenediamine and a reactive diluent to continue the reaction for 2 h to 3 h to obtain an epoxy resin grafted polyurethane component; Step three, adding an accelerator and a photoinitiator to the epoxy resin grafted polyurethane component, continuing the reaction for 0.5h to 1h, and then adding a filler and stirring evenly to obtain a bipolar plate adhesive.

2. The bipolar plate frame adhesive according to claim 1, characterized in that: It is composed of the following raw material components in parts by weight: 25 parts of diphenylmethane diisocyanate; 30 parts of polybutylene adipate diol with a molecular weight of 3000; Dow 2120 polyether polyol 22 parts; Epoxy resin 20 parts; Active diluent 15 parts; 3 parts of catalyst; 2 parts of accelerator; 3.7 parts of photoinitiator; 3 parts of filling.

3. The bipolar plate frame adhesive according to claim 1, characterized in that: The photoinitiator is at least one of iodonium salt, sulfonium salt and iron arene.

4. An application of the bipolar plate frame adhesive as claimed in any one of claims 1 to 3 in bonding the bipolar plate frame of a battery.

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