Interpenetrating network controllable polymerization polyurethane adhesive and preparation method

Abstract

The application provides an interpenetrating network controllable polymerization polyurethane adhesive, which comprises two components A and B, and the mass mixing ratio of the component A and the component B is 1-2:1; according to the mass fraction, the component A comprises 20%-90% N-substituted phthalimide, 10%-70% polyhydric alcohol, 1%-10% ethanol, 0-0.5% water, 0.1%-1% metal catalyst and 0-30% filler; and the component B comprises 20%-90% polyisocyanate, 20%-70% isocyanate-terminated prepolymer and 0.5%-5% thermally induced base generator. The interpenetrating network controllable polymerization polyurethane adhesive of the application utilizes the reaction of N-substituted phthalimide under the conditions of alkaline condition and solvent to generate primary amine, the primary amine and the isocyanate component rapidly react to generate polyurea, the residual isocyanate and the polyhydric alcohol and ethanol react to generate polyurethane in the later period, the polyurea-polyurethane interpenetrating network structure is further formed to improve the bulk strength, and the pot life and the initial bonding strength are controlled and adjusted by adjusting the ratio of the N-substituted phthalimide and the polyhydric alcohol.

Description

Technical Field

[0001] This invention relates to an interpenetrating network controllable polymerizable polyurethane adhesive and its preparation method, belonging to the field of adhesive technology. Background Technology

[0002] When using two-component polyurethane adhesives to bond substrates on industrial production lines, it is desirable for the adhesive to have a long pot life and the ability to rapidly cure upon heating to form bond strength. This better meets the process requirements of industrial production and improves production efficiency. However, conventional two-component polyurethane adhesives tend to have slow curing speeds if the pot life is long, and short pot lifespans if the curing speed is fast, making it difficult to achieve both a long pot life and a fast curing speed. The present invention provides an interpenetrating network controllable polymerizable polyurethane adhesive that, while possessing a long pot life, also allows for rapid initial curing upon heating to form bond strength. Summary of the Invention

[0003] To address the challenge that conventional two-component polyurethane adhesives struggle to achieve both a long pot life and rapid initial curing, the present invention aims to provide an interpenetrating network controllable polymerizable polyurethane adhesive that, while possessing a long pot life, can rapidly achieve initial curing upon heating to form adhesive strength.

[0004] The technical solution of this invention to solve the above problems is: providing an interpenetrating network controllable polymerizable polyurethane adhesive, which comprises two components, A and B, with a mass mixing ratio of component A to component B of 1 to 2:1. By mass fraction, component A contains 20% to 90% N-substituted phthalimide, 10% to 70% polyol, 1% to 10% ethanol, 0% to 0.5% water, 0.1% to 1% metal catalyst, and 0% to 30% filler; component B contains 20% to 90% polyisocyanate, 20% to 70% isocyanate-terminated prepolymer, and 0.5% to 5% thermally alkali-generating agent.

[0005] Furthermore, the N-substituted phthalimide in component A refers to the product obtained by reacting N-hydroxymethyl phthalimide with diisocyanate. The synthesis method involves reacting N-hydroxymethyl phthalimide and diisocyanate at a molar ratio of 2–2.2:1 at 70–90°C under the action of a catalyst until the -NCO group disappears.

[0006] Furthermore, the diisocyanate in the N-substituted phthalimide synthesis method of component A is an aliphatic or alicyclic diisocyanate, including isophorone diisocyanate (IPD I), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), methylcyclohexane diisocyanate (HTDI), etc.

[0007] Furthermore, the polyol in component A is an alcohol with a degree of difunctionality greater than or equal to that of polyols, and different molecular structures can be selected as needed, including polyethers, polyesters, polyether esters, polyolefins, and other polyols.

[0008] Furthermore, the metal catalyst in component A refers to an organic catalyst containing tin, bismuth, zinc or zirconium, preferably an organic bismuth catalyst.

[0009] Furthermore, the polyisocyanate in component B refers to an isocyanate with a degree of difunctionality greater than or equal to that of a difunctional isocyanate, preferably an isocyanate with a degree of difunctionality greater than that of a difunctional isocyanate, such as polyphenyl polymethylene polyisocyanate (PAPI).

[0010] Furthermore, the isocyanate-terminated prepolymer in component B refers to the product obtained by reacting an isocyanate with a functionality greater than or equal to that of a difunctional isocyanate and a diol at a functional group molar ratio of 1 to 2:1 at 70-90°C until -NCO reaches the designed value, preferably a difunctional isocyanate.

[0011] Furthermore, the thermally alkali-generating agent in component B refers to a raw material that is stable at room temperature and can release a strong alkaline substance under heating conditions. The heating temperature is preferably 40℃-110℃, more preferably 50℃-80℃, such as San-Apro's U-CATSA1, EVONIK's POLYCAT SA1, POLYCAT SA101 and POLYCAT SA8.

[0012] The beneficial effects of this invention are as follows: This invention prepares an interpenetrating network controllable polymerizable polyurethane adhesive. It utilizes N-substituted phthalimide to react under alkaline conditions and in the presence of a solvent to generate a primary amine. The primary amine and isocyanate component rapidly react to form a polyurea. Later, the remaining isocyanate reacts with a polyol and ethanol to generate polyurethane, forming a polyurea-polyurethane interpenetrating network structure that further improves the bulk strength. Furthermore, the thermogenic alkali-generating agent only generates alkali under heating conditions and is stable at room temperature, allowing for control of the reaction through heating. Moreover, the pot life and initial bond strength can be controlled and adjusted by adjusting the ratio of N-substituted phthalimide to polyol. Detailed Implementation

[0013] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0014] Example 1

[0015] Component A: 338g N-hydroxymethyl phthalimide, 152.8g HDI and 1g Bicat8118 were added sequentially to the reactor and reacted at 80-85℃ until the -NCO group disappeared. After cooling to room temperature, 141g VERTELLUS T-400 castor oil modified polyol, 0.4g water, 23g ethanol, 2.7g Bicat8124 and 7.33g fumed silicon were added, stirred and mixed evenly, and then sealed and stored.

[0016] Component B: 125g of polycarbonate diol with a molecular weight of 500 and 120g of 4,4'-diphenylmethane diisocyanate were added sequentially to the reactor. The reaction was carried out at 75-80℃ until the -NCO group content was ≤7.87%, at which point heating was stopped. After cooling to room temperature, 407g of PAPI and 15g of POLYCAT SA101 were added, and the mixture was stirred and mixed evenly under vacuum. The mixture was then sealed and stored under nitrogen.

[0017] Example 2

[0018] Component A: 277g N-hydroxymethyl phthalimide, 125.2g HDI and 0.83g Bicat8118 were added sequentially to the reactor. The reaction was carried out at 80-85℃ until the -NCO group disappeared. After cooling to room temperature, 197.4g VERTELLUS T-400 castor oil modified polyol, 0.4g water, 23g ethanol, 2.7g Bicat8124, 7.33g fumed silicon and 33.77g aluminum hydroxide were added. The mixture was stirred and mixed evenly and then sealed for storage.

[0019] Component B is the same as in Example 1.

[0020] Example 3

[0021] Component A: 230.3g N-hydroxymethyl phthalimide, 104g HDI and 0.7g Bicat8118 were added sequentially to the reactor. The reaction was carried out at 80-85℃ until the -NCO group disappeared. After cooling to room temperature, 233g VERTELLUS T-400 castor oil modified polyol, 0.4g water, 23g ethanol, 2.7g Bicat8124, 7.33g fumed silicon and 65g aluminum hydroxide were added. The mixture was stirred and mixed evenly, and then sealed and stored.

[0022] Component B is the same as in Example 1.

[0023] Comparative Example 1

[0024] Component A: 496.2g N-hydroxymethyl phthalimide, 141g VERTELLUS T-400 castor oil modified polyol, 0.4g water, 23g ethanol, 2.7g Bicat8124, and 7.33g fumed silica are added sequentially, stirred until homogeneous, and then sealed and stored.

[0025] Component B is the same as in Example 1.

[0026] Comparative Example 2

[0027] Component A: 604.43g VERTELLUS T-400 castor oil modified polyol, 0.4g water, 23g ethanol, 2.7g Bicat8124, 7.33g fumed silicon, and 33.77g aluminum hydroxide were added sequentially, stirred until homogeneous, and then sealed and stored.

[0028] Component B is the same as in Example 1.

[0029] The performance of the polyurethane adhesive of the present invention was tested through the following experiments.

[0030] Pot life: The viscosity of the mixture of components A and B of the embodiment and the comparative example at a mass ratio of 1:1 is tested. The time when the viscosity increases by 200% at room temperature is defined as the pot life.

[0031] Adhesion strength: The components A and B of the above embodiment and the comparative example were mixed at a mass ratio of 1:1 and then bonded to a 3003Al substrate. The mixture was heated at 70°C for 2 minutes and then the shear strength was tested at room temperature. The mixture was then heated at 70°C for 2 minutes and then left at room temperature for 24 hours before testing the shear strength.

[0032] High and low temperature impact strength: The components A and B of the above embodiment and the comparative example were mixed at a mass ratio of 1:1 and bonded to a 3003Al substrate. The mixture was heated at 70°C for 2 minutes and then placed at room temperature for 24 hours. After that, it was placed in a high and low temperature impact chamber of -40°C to 85°C. The chamber was held at -40°C for 0.5 hours, and the high and low temperature transition time was within 1 minute. The chamber was held at 85°C for 0.5 hours, which constituted one cycle. After 2000 cycles, the shear strength was tested.

[0033] The test results are shown in Table 1.

[0034] Table 1. Comparison test results between the examples and the comparative examples.

[0035]

[0036]

[0037] As can be seen from the above results, compared with conventional two-component polyurethane adhesives, the interpenetrating network controllable polymerizable polyurethane adhesive of the present invention has a long pot life at room temperature, and can quickly and initially cure to form adhesive strength after heating. After curing, it forms an interpenetrating network structure, which further improves the adhesive strength and has good resistance to high and low temperature impact. At the same time, the pot life and initial adhesive strength can be adjusted and controlled by adjusting the proportion of component raw materials.

[0038] The embodiments described above are merely illustrative of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An interpenetrating network controllable polymerizable polyurethane adhesive, comprising two components, A and B, wherein the mass mixing ratio of component A to component B is 1–2:1; by mass fraction, component A comprises 20%–90% N-substituted phthalimide, 10%–70% polyol, 1%–10% ethanol, 0%–0.5% water, 0.1%–1% metal catalyst, and 0%–30% filler; component B comprises 20%–90% polyisocyanate, 20%–70% isocyanate-terminated prepolymer, and 0.5%–5% thermally alkali-generating agent; the total mass fraction of all raw materials in component A does not exceed 100%, and the total mass fraction of all raw materials in component B does not exceed 100%. The N-substituted phthalimide is a product obtained by reacting N-hydroxymethyl phthalimide with diisocyanate; its synthesis method is to react N-hydroxymethyl phthalimide and diisocyanate at a molar ratio of 2 to 2.2:1 at 70-90°C under the action of a catalyst until the -NCO group disappears.

2. The interpenetrating network controllable polymerizable polyurethane adhesive according to claim 1, characterized in that, The diisocyanate comprises one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and methylcyclohexane diisocyanate.

3. The interpenetrating network controllable polymerizable polyurethane adhesive according to claim 1, characterized in that, The polyol is an alcohol with a difunctionality greater than or equal to that of a polyether polyol, including one of polyether polyol, polyester polyol, polyether ester polyol, and polyolefin polyol; the metal catalyst is an organic catalyst containing tin, bismuth, zinc, or zirconium.

4. The interpenetrating network controllable polymerizable polyurethane adhesive according to claim 1, characterized in that, The polyisocyanate is an isocyanate with a functionality greater than or equal to that of a difunctional ester.

5. The interpenetrating network controllable polymerizable polyurethane adhesive according to claim 1, characterized in that, The isocyanate-terminated prepolymer refers to the product obtained by reacting an isocyanate with a functional group greater than or equal to that of a difunctional diol with a functional group molar ratio of 1 to 2:1 at 70-90°C until -NCO reaches the designed value.

6. The interpenetrating network controllable polymerizable polyurethane adhesive according to claim 1, characterized in that, The thermogenic alkali-producing agent is one of San-Apro's U-CAT SA1, EVONIK's POLYCAT SA1, POLYCAT SA101, and POLYCAT SA8.

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