Chain extender, preparation method thereof and high-strength two-component heat-conducting polyurethane structural adhesive

Abstract

The present application relates to polyurethane adhesive technical field, especially a kind of chain extender and its preparation method and high-strength two-component heat-conducting polyurethane structural adhesive;The chain extender is composed of epoxy compound, polyamine and epsilon-caprolactone monomer, the molar ratio of polyamine and epoxy compound is greater than 1.0, the molar ratio of unreacted polyamine and epsilon-caprolactone monomer is 1:0.5~1:10;The present application discloses a method for modifying polyurethane using epoxy compound and epsilon-caprolactone monomer, which fully combines the advantages of organic amine, epoxy compound and epsilon-caprolactone monomer, so that it effectively meets the demand of two-component polyurethane sizing process, and can be used in conventional two-component construction system;The present application modifies the di-epoxy compound or epsilon-caprolactone monomer with high-activity polyamine, and cooperates with high-activity polyether polyol or small-molecule chain extender, to achieve room temperature curing for seven days to reach more than 28Mpa shear strength.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of polyurethane adhesives, and in particular to a chain extender, a preparation method thereof and high-strength two-component heat-conducting polyurethane structural adhesive. BACKGROUND

[0002] The application of polyurethane has been developing with the development of chain extenders since the Second World War. The rich types of polyether and polyester polyols, polyamine and other chain extenders greatly expand the application range of polyurethane. Although the development of isocyanate components is also very crucial, the related technology is mastered by a few large companies. It is not an exaggeration to say that the development of polyurethane chain extenders is the key to further breakthrough in related fields. In the current rapid development of energy storage and new energy vehicles, rapid assembly, reduced positioning time and increased heat conduction function are new requirements for the adhesive industry. The development of a two-component polyurethane with high bonding strength, excellent comprehensive performance and heat conduction function can greatly expand the application range of polyurethane structural adhesive.

[0003] The two-component polyurethane introduced in patent CN110760286A has a shear strength of 24 MPa, but its mixing method is mass ratio, it has no heat conduction performance, and more conventional raw materials are used in the chain extender. The strength increasing effect must rely on complex catalysts or small molecule chain extenders. Patent CN111548763A introduces a high-strength and high-weatherability two-component polyurethane structural adhesive with heat conduction function, but the chain extender uses linear macromolecular hydroxymethyl acrylate resin and other expensive modified polyols, the mixing method is mass ratio, the production process is complex, and the shear strength is far less than 20 MPa. The shear strength of the two-component polyurethane introduced in CN108102596A is close to 20 MPa, but it is still mixed according to the mass ratio (5:1), and the application range is limited. As can be seen from the existing literature, to make a high-strength two-component polyurethane structural adhesive, only aromatic isocyanate can be used as the curing agent or more small molecules can be used as the hard segment to improve the shear strength. The mass ratio of hydroxyl and NCO components is maintained in the range of 6-2:1, and it is difficult to achieve a volume ratio of 1:1. Therefore, the mixing method in the literature is mass ratio, and the long-term storage stability of the adhesive cannot be achieved, which is not suitable for the use process of rapid assembly. Therefore, the development of a two-component polyurethane with high bonding strength, excellent comprehensive performance, capable of being operated by a conventional glue gun at a volume ratio of 1:1 and having heat conduction function can not only make up for the disadvantages of two-component polyurethane adhesive in terms of high-temperature resistance and bonding strength compared with epoxy resin and acrylate structural adhesive, but also fully exert the toughness of polyurethane, and further expand the application range of polyurethane structural adhesive. SUMMARY

[0004] The application aims to provide a chain extender, a preparation method thereof and a high-strength two-component heat-conducting polyurethane structural adhesive, so as to solve at least one of the above technical problems.

[0005] To solve the above technical problems, the application adopts the technical scheme as follows.

[0006] The chain extender is composed of an epoxy compound, a polyamine and an epsilon-caprolactone monomer, the molar ratio of the polyamine to the epoxy compound is greater than 1.0, and the molar ratio of the unreacted polyamine to the epsilon-caprolactone monomer is 1:0.5-1:10.

[0007] Further, the main chain contains a polyhydroxyl compound with N atoms, benzene rings and flexible chain segments, and the number of hydroxyl groups is greater than or equal to 2, which is gently controllable when reacting with NCO, and enriches the types of polyols.

[0008] Further, the molar ratio of the polyamine to the epoxy compound is 1.05-2.5, and the molar ratio of the unreacted polyamine to the epsilon-caprolactone monomer is 1:0.5-1:3.

[0009] Further, the epoxy compound is selected from one or more of bisphenol F epoxy resin, bisphenol A epoxy resin, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol glycidyl ether, 3,4-epoxycyclohexyl-3',4'-epoxycyclohexane carboxylate, 1,4-butanediol diglycidyl ether and ethylene glycol diglycidyl ether.

[0010] Further, the polyamine includes MOCA, E-300, E-100, MDEA, MCDEA, MDA, MOEA, Unilink4200, Unilink4100, aspartic polyurea resin or modified amine chain extender (such as Guangzhou Yourun Chemical TDMA-G55), and the polyamines can be mixed for use to meet different performance requirements.

[0011] A preparation method of the chain extender, the preparation method comprising the following steps:

[0012] S1 mixing and uniformly heating the epoxy compound and the polyamine in proportion, and reacting at 80-150 DEG C for 0.5-5 h, and vacuumizing for 1 h;

[0013] S2 adding a calculated amount of epsilon-caprolactone monomer into the above reaction product, and refluxing and reacting at 90-130 DEG C for 0.5-5 h, and vacuumizing for 1 h after the reaction is completed to obtain the chain extender, which is sealed and stored.

[0014] Further, the chain extender comprises a component A and a component B, wherein the raw material composition of the component A comprises the chain extender according to any one of claims 1-4, polyether polyol, small molecule polyol, thixotropic agent and heat-conducting filler.

[0015] The raw material composition of the B component includes: a polyisocyanate curing agent or isocyanate-terminated prepolymer, a plasticizer, a thermal conductive filler, a silane coupling agent, a thixotropic agent and a water removal agent.

[0016] Further, the volume ratio of the A component to the B component is 1:1.

[0017] Further, the mass part composition of the raw materials in the A component is as follows:

[0018] Chain extender 10-55 parts, polyether polyol 0-20 parts, small molecule polyol 0-10 parts, thixotropic agent 0-2 parts, thermal conductive filler 50-95 parts.

[0019] Further, the mass part composition of the raw materials in the B component is as follows:

[0020] Polyisocyanate curing agent or isocyanate-terminated prepolymer 10-55 parts, plasticizer 0-5 parts, thermal conductive filler 50-95 parts, silane coupling agent 0-5 parts, thixotropic agent 0-2 parts, water removal agent 0.5-2 parts.

[0021] The beneficial effects of the technical solutions in the application are:

[0022] The application develops a method for modifying polyurethane using an epoxy compound and epsilon-caprolactone monomer, which fully combines the advantages of organic amine, epoxy compound and epsilon-caprolactone monomer, effectively meets the demand of two-component polyurethane sizing process, and can be used in conventional two-component construction system.

[0023] The two-component polyurethane structural adhesive designed in the application can realize rapid curing without adding a catalyst, the raw materials involved are low in cost, the operation is simple, industrialized production is suitable, the strength is high, the high thermal conductivity demand can be met, the application is more environmentally friendly, and the application range is wider.

[0024] The application modifies a high-activity polyamine with a bis-epoxy compound or epsilon-caprolactone monomer, cooperates with a high-activity polyether polyol or a small molecule chain extender, and realizes room temperature curing for seven days to reach a shear strength of more than 28Mpa.

[0025] The self-made chain extender has low viscosity, good compatibility with conventional chain extenders, and strong infiltration to thermal conductive powder, and is more convenient to use. DETAILED DESCRIPTION

[0026] The present application is not limited to the following specific embodiments, and those skilled in the art can implement the present application in other various embodiments according to the disclosure of the present application, or any simple changes or modifications made by using the design structure and ideas of the present application, which all fall within the protection scope of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0027] A chain extender, which is composed of an epoxy compound, a polyamine and epsilon-caprolactone monomers, the molar ratio of the polyamine to the epoxy compound is greater than 1.0, and the molar ratio of the unreacted polyamine to the epsilon-caprolactone monomers is 1:0.5-1:10. Preferably, the molar ratio of the polyamine to the epoxy compound is 1.05-2.5, and the molar ratio of the unreacted polyamine to the epsilon-caprolactone monomers is 1:0.5-1:3.

[0028] In the formula, the epoxy compound and the epsilon-caprolactone monomers are chain growth units, the polyamine is an initiator (or ring-opening agent), the epoxy compound provides rigidity, and the epsilon-caprolactone monomers provide toughness.

[0029] The raw materials of the polyurethane chain extender prepared in the present application have a wide source and low price, and are suitable for industrial production. The molar ratio of the polyamine to the epoxy compound is greater than 1.0, which ensures complete ring opening of the epoxy compound and does not affect the stability of the product, and also ensures complete ring opening of the epsilon-caprolactone monomers and provides toughness of the polyurethane adhesive.

[0030] The chain extender in the present application can also be used in combination with the polyether commonly used in two-component polyurethane and small molecule chain extenders.

[0031] The method for preparing the chain extender in the present application comprises the following steps:

[0032] S1. The epoxy compound and the polyamine are mixed in proportion and heated to uniformity, and reacted at 80-150 DEG C for 0.5-5 h, and then water is removed by vacuum extraction;

[0033] S2. The calculated amount of epsilon-caprolactone monomers is added to the above reaction product, and refluxed at 90-130 DEG C for 0.5-5 h. After the reaction is completed, water is removed by vacuum extraction, and the chain extender is obtained and stored in a sealed container.

[0034] It needs to be pointed out that the conventional epoxy modified polyurethane cannot balance the strength and normal temperature performance, the two-component polyurethane modified chain extender involved in the present application combines the two basic principles of amine ring-opening epoxy and ring-opening epsilon-caprolactone monomer, so that the reactivity is equivalent to the reactivity of ordinary small molecule polyether polyol, the use process and strength balance of the two-component structural adhesive are effectively balanced, and long-term storage is also achieved. From the molecular structure, the step provides a method for toughening the epoxy compound, and a polyhydroxyl compound with N atoms, benzene rings and flexible chain segments in the main chain is synthesized, the compound is slowly and controllably reacted with NCO, and the type of polyol is enriched. The rapid curing and positioning can be realized, and the catalyst can not be used, thereby increasing the stability of the two components. The preparation method of the chain extender can also adopt a one-step method.

[0035] In addition, it needs to be pointed out that the preparation method of the chain extender in the present application can add conventional polyester synthesis catalysts, including conventional metal catalysts (organotin, organotitanium, organobismuth, etc.) or organic catalysts (organoboron, polyamine salt, etc.), for example, can be: tetrabutyl titanate, dibutyltin dilaurate, the addition amount of the catalyst is usually 0.01%-1.0%, so as to promote the ring-opening reaction to occur, reduce the reaction time and temperature, and the catalyst can also not be added.

[0036] Example 1

[0037] Chain extender preparation: 120g Unilink4200, 90g epoxy compound E-51 are weighed in a 500ml three-necked flask, heated and mixed, after reaction at 100℃ for 2h, the temperature is increased to 110℃ to remove water for 0.5h, and then the temperature is decreased to 80℃, 42g of epsilon-caprolactone monomer and 0.06g of 10% T-12 epsilon-caprolactone monomer solution are added, and the reaction is carried out at 110℃ for 2h, then vacuum dehydration is carried out for 1h, and then the temperature is decreased to discharge the material, and the sealed preservation is carried out.

[0038] Preparation of component A: 25.5 parts of the chain extender of example 1, 15 parts of polyether polyol NJ-307, 3 parts of polyether polyol NJ-6249 are added into a container and stirred uniformly, then 4 parts of 3A molecular sieve, 52 parts of heat-conducting compound powder and 0.5 parts of fumed silica H20 (Wacker) are added, and then the vacuum is extracted and stirred for 1h, so as to obtain component A. The viscosity is 48000mpa.s at 25℃, 14# rotor and 10R rotation speed.

[0039] Preparation of component B prepolymer: 10.5 parts of castor oil and 5.5 parts of polyether polyol MN-3050D are added into a three-necked flask, heated to 120℃, and then dehydrated at a vacuum degree of 0.9MPa for 1h, then the temperature is decreased to 60℃, 31 parts of PM200 (Wanhua) and 53 parts of MDI-100L (Wanhua) are added, and then the temperature is slowly increased to 80℃, and the reaction is carried out for 2-3h, then the temperature is decreased to discharge the material, and the sealed preservation is carried out.

[0040] Preparation of Component B: 45 parts of component B prepolymer, 2 parts of di-n-undecyl phthalate, 52 parts of thermally conductive compound powder, 0.5 parts of fumed silica H2O (Wacker), and 0.5 parts of dehydrating agent were stirred under vacuum for 2 hours to obtain component B. The viscosity was 62000 mPa·s at 25℃, with a #14 rotor and a rotation speed of 10 RPM.

[0041] Place components A and B in a 1:1 volume ratio dual tube, connect the static mixing head to the 1:1 volume ratio dual tube glue gun, and apply the glue directly at room temperature.

[0042] Example 2

[0043] Chain extender preparation: Weigh 60g E-300, 90g aspartic polyurea resin LF-AP105 (Nanjing Lanfeng New Material Technology Co., Ltd.), and 60g epoxy resin E-51 into a 500ml three-necked flask. Mix while heating and react at 110℃ for 1.5h. After removing water for 0.5h, cool to 80℃ and add 75g ε-caprolactone monomer. React at 110℃ for 2h, remove water under vacuum for 1h, cool and discharge, and seal for storage.

[0044] Preparation of Component A: 17 parts of the chain extender from Example 2, 3.5 parts of castor oil polyol, and 2 parts of polyether polyol DV-125 were added to a container and stirred until homogeneous. Then, 4 parts of 3A molecular sieve, 73 parts of thermally conductive compound powder, and 0.5 parts of fumed silica H2O (Wacker) were added. The mixture was stirred under vacuum for 1 hour to obtain Component A. At 25°C, with a #14 rotor and a rotation speed of 10R, the viscosity was 144000 mPa·s.

[0045] Preparation of Component B: 15 parts of the prepolymer of Component B from Example 1, 9 parts of polymeric MDI (Wanhua PM200), 75 parts of thermally conductive compound powder, 0.5 parts of fumed silica H2O (Wacker), and 0.5 parts of dehydrating agent were stirred under vacuum for 2 hours to obtain Component B. The viscosity was 176000 mPa·s at 25°C, with a #14 rotor and a rotation speed of 10 RPM.

[0046] Place components A and B in a 1:1 volume ratio dual tube, connect the static mixing head to the 1:1 volume ratio dual tube glue gun, and apply the glue directly at room temperature.

[0047] Example 3

[0048] Chain extender preparation: Weigh 30g TDMA-G55, 114g Unilink4200, and 60g bisphenol F epoxy resin into a 500ml three-necked flask. Mix while heating and react at 110℃ for 2h. After removing water for 0.5h, cool to 80℃ and add 75g ε-caprolactone monomer and 0.01g tetrabutyl titanate. React at 110℃ for 1.5h, remove water under vacuum for 1h, cool and discharge, and seal for storage.

[0049] A component preparation: 12 parts of the chain extender of Example 3, 2.5 parts of polyether polyol NJ-307, 1 part of dipropylene glycol were added into a container and stirred uniformly, then 4 parts of 3A molecular sieve, 80 parts of heat-conducting compound powder, 0.5 parts of fumed silica H20 (Wacker) were added, and stirred for 1 h under vacuum, to obtain the A component. The viscosity was 192000 mPa.s at 25℃, 14# rotor, 10R rotation speed.

[0050] B component preparation: 8 parts of the prepolymer of Example 1B component, 8 parts of polymeric MDI (Wanhua PM200), 1 part of di-n-undecyl phthalate, 82 parts of heat-conducting compound powder, 0.5 parts of fumed silica H20 (Wacker), 0.5 parts of water removal agent were stirred for 2 h under vacuum, to obtain the B component. The viscosity was 226000 mPa.s at 25℃, 14# rotor, 10R rotation speed.

[0051] The A component and the B component were respectively placed in a double tube with a volume ratio of 1:1, and connected to a static mixing head to obtain a double tube adhesive with a volume ratio of 1:1. The adhesive could be directly squeezed out at room temperature.

[0052] Comparative Example

[0053] Chain extender preparation: 225 g of castor oil, 33 g of polyether polyol MN1000, and 16.5 g of trimethylolpropane were weighed into a 500 ml three-necked flask, and water was removed at 120℃ for 2 h. After cooling to 80℃, 25.5 g of liquefied MDI (Wanhua MDI-100L) was added, and reacted at 80℃ for 2.5 h. After cooling, the product was discharged and stored in a sealed container.

[0054] A component preparation: 25 parts of the chain extender of the comparative example, 15 parts of polyether polyol NJ-307, 3 parts of polyether polyol NJ-6249 were added into a container and stirred uniformly, then 4 parts of 3A molecular sieve, 52 parts of heat-conducting compound powder, 0.5 parts of fumed silica H20 (Wacker), 0.5 parts of 5% T-12 castor oil solution were added, and stirred for 1 h, to obtain the A component. The viscosity was 39000 mPa.s at 25℃, 14# rotor, 10R rotation speed.

[0055] B component preparation: 20 parts of the prepolymer of B component, 25 parts of polymeric MDI (Wanhua PM200), 54 parts of heat-conducting compound powder, 0.5 parts of fumed silica H20 (Wacker), 0.5 parts of water removal agent were stirred for 2 h under vacuum, to obtain the B component. The viscosity was 38000 mPa.s at 25℃, 14# rotor, 10R rotation speed.

[0056] The A component and the B component were respectively placed in a double tube with a volume ratio of 1:1, and connected to a static mixing head to obtain a double tube adhesive with a volume ratio of 1:1. The adhesive could be directly squeezed out at room temperature.

[0057] It should be noted that the remaining raw materials in component A include polyether polyol, thixotropic agent, thermal conductive filler, silane coupling agent, etc., which are all conventional products on the market and can be directly mixed with the above chain extender; the isocyanate in component B can be used alone or after preparation of a prepolymer, and aromatic isocyanate is preferred.

[0058] Performance test

[0059] The shear strength is detected according to GB / T7124-2008 method, and aluminum sheet and stainless steel plate are used for testing, respectively; the operable time is detected according to GB / T7123.1-2015 method.

[0060] Table 1 performance test result statistics table

[0061]

[0062]

[0063] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not a limitation on the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. An extender, characterized by: The chain extender is composed of an epoxy compound, a polyamine and epsilon-caprolactone monomers, the molar ratio of the polyamine to the epoxy compound is greater than 1.0, and the molar ratio of the unreacted polyamine to the epsilon-caprolactone monomers is 1:0.5-1:10; The preparation method of the chain extender comprises the following steps: S1 uniformly heating and mixing the epoxy compound and the polyamine in proportion, reacting at 80-150 DEG C for 0.5-5 h, and vacuumizing for 1 h to obtain a reaction product; S2 adding the epsilon-caprolactone monomers into the reaction product obtained in S1, refluxing at 90-130 DEG C for 0.5-5 h, vacuumizing for 1 h after the reaction is completed, and obtaining the chain extender, which is sealed and stored; The epoxy compound is selected from one or more of bisphenol F epoxy resin, bisphenol A epoxy resin, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol glycidyl ether, 3,4-epoxycyclohexyl-3',4'-epoxycyclohexane carboxylate and ethylene glycol diglycidyl ether; The polyamine is selected from one or more of MOCA, E-300, E-100, MCDEA, MDA, MOEA, Unilink 4200, Unilink 4100 and aspartic polyurea resin.

2. The chain extender of claim 1, wherein: The molar ratio of the polyamine to the epoxy compound is 1.05-2.5, and the molar ratio of the unreacted polyamine to the epsilon-caprolactone monomers is 1:0.5-1:

3.

3. A high-strength two-component heat-conducting polyurethane structural adhesive, characterized in that: The A component and the B component are included, wherein the raw material composition of the A component comprises the chain extender according to any one of claims 1-2, a polyether polyol, a small molecule polyol, a thixotropic agent and a thermal conductive filler; The raw material composition of the B component comprises a polyisocyanate curing agent or an isocyanate-terminated prepolymer, a plasticizer, a thermal conductive filler, a silane coupling agent, a thixotropic agent and a water removal agent.

4. The high-strength two-component heat-conducting polyurethane structural adhesive according to claim 3, characterized in that: The volume ratio of the A component to the B component is 1:

1.

5. The high-strength two-component thermally conductive polyurethane structural adhesive according to claim 4, characterized in that: The mass part composition of the raw materials in the A component is as follows: Chain extender 10-55 parts, polyether polyol 2-20 parts, small molecule polyol 1-10 parts, thixotropic agent 0.5 parts, thermal conductive filler 50-95 parts.

6. The high-strength two-component heat-conducting polyurethane structural adhesive according to claim 5, characterized in that: The mass part composition of the raw materials in the B component is as follows: Polyisocyanate curing agent or isocyanate-terminated prepolymer 10-55 parts, plasticizer 0-5 parts, thermal conductive filler 50-95 parts, silane coupling agent 0-5 parts, thixotropic agent 0.5 parts, water removal agent 0.5-2 parts.

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