Polyurethane adhesive as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of adhesives, and discloses a polyurethane adhesive as well as a preparation method and application thereof. The polyurethane adhesive comprises a component A and a component B, the component A is prepared from the following raw materials: polycarbonate diol, polytetrahydrofuran ether glycol, polyoxypropylene ether glycol and isocyanate; the component B is prepared from the following raw materials: polycaprolactone tetraol, dimer acid polyester glycol and a silane coupling agent. The polyurethane adhesive has the advantages of excellent low temperature resistance, high bonding strength, stable long-term storage performance and low yellowing tendency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of adhesives, and particularly relates to a polyurethane adhesive as well as a preparation method and application thereof. BACKGROUND

[0002] Polyurethane adhesive is an important bonding material widely used in various industrial fields. Its excellent bonding performance, such as excellent adhesion to various substrates, good heat resistance, chemical resistance and aging resistance, etc., makes it play an important role in many fields such as shoemaking, packaging, building, automobile, electronics, etc.

[0003] At present, the bonding performance under low temperature environment is an important problem that polyurethane adhesive needs to face. When the temperature drops, the adhesion of the adhesive will decrease significantly, resulting in the decrease of the stability and reliability of the bonding structure. The polyurethane adhesive becomes too brittle and hard at low temperature, and cannot effectively bond the substrates, and even may produce cracks at the bonding interface, resulting in bonding failure. In addition, the polyurethane adhesive also has the problems of poor storage stability and easy yellowing. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a polyurethane adhesive as well as a preparation method and application thereof. The polyurethane adhesive has excellent low temperature resistance, high bonding strength, stable long-term storage performance and is not easy to yellow.

[0005] In a first aspect, the present application provides a polyurethane adhesive, which comprises component A and component B; the raw materials of the component A comprise polycarbonate diol, polytetrahydrofuran ether diol, polyoxypropylene ether diol and isocyanate; the raw materials of the component B comprise polycaprolactone tetrol, dimer acid polyester diol and silane coupling agent.

[0006] Specifically, in the raw materials of the component A, the flexible aliphatic chain segment in the molecular chain of the polycarbonate diol provides the ability of chain segment movement, and the glass transition temperature can be as low as-50℃ or below, while the carbonate group can enhance the hydrogen bonding force with the substrate and improve the cohesive strength; the aliphatic structure and hydrolysis-resistant carbonate group therein endow high hydrolysis resistance and weather resistance, and the polyurethane adhesive is not easy to yellow. The polytetrahydrofuran ether diol has a highly regular ether bond structure, which can provide flexibility and impact resistance at low temperature, and the polycarbonate diol can inhibit the crystallization tendency of the polytetrahydrofuran ether diol to a certain extent, thereby maintaining the low-temperature toughness. The addition of the polyoxypropylene ether diol can break the crystallization of the polytetrahydrofuran ether diol, and the random structure of the polyoxypropylene ether diol can destroy the regularity of the molecular chain of the polytetrahydrofuran ether diol, thereby preventing low-temperature embrittlement.

[0007] Specifically, in the raw materials of the B component, the tetra-functionality structure of polycaprolactone tetrol builds a close network, the crosslinking density is high, the cohesion strength is improved, and a high crosslinking density interface layer is formed with isocyanate. The dimer acid polyester diol has excellent flexibility, can avoid the brittleness risk caused by the high crosslinking of polycaprolactone tetrol, balances high strength and flexibility, prevents brittle fracture of the high crosslinking system, and also has excellent hydrolysis resistance. The addition of the silane coupling agent can increase the effect of interfacial bonding, so that the bonding stability between the polyurethane adhesive and the substrate is further improved.

[0008] The polyurethane adhesive has obvious improvement in low-temperature resistance, bonding strength, long-term storage performance and weather resistance, and is not prone to yellowing.

[0009] In some embodiments of the present application, the mass ratio of the A component and the B component is (1.2-1.8):1.

[0010] In some embodiments of the present application, the raw materials of the A component include, by mass fraction, polycarbonate diol 10-20 parts, polytetrahydrofuran ether diol 15-30 parts, polypropylene oxide ether diol 20-30 parts, and isocyanate 50-80 parts.

[0011] In some embodiments of the present application, the raw materials of the B component include, by mass fraction, polycaprolactone tetrol 15-25 parts, dimer acid polyester diol 20-40 parts, and silane coupling agent 0.5-1.5 parts.

[0012] In some embodiments of the present application, the isocyanate includes at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), and diphenylmethane diisocyanate (MDI).

[0013] In some embodiments of the present application, the silane coupling agent includes at least one of γ-glycidyl ether propyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl triethoxysilane, γ-(methacryloyloxy) propyl trimethoxysilane, and γ-(2,3-epoxypropoxy) propyl trimethoxysilane.

[0014] The second aspect of the present application provides a preparation method of the polyurethane adhesive of the first aspect of the present application, including the following steps:

[0015] S1, mixing the polycarbonate diol, the polytetrahydrofuran ether diol, the polypropylene oxide ether diol, and the isocyanate, heating and stirring to obtain the A component;

[0016] S2, mixing the polycaprolactone tetrol, dimer acid polyester diol and silane coupling agent, heating and stirring to obtain the B component;

[0017] S3, mixing the A component and B component to obtain the polyurethane adhesive.

[0018] In some embodiments of the present application, in S1, the heating temperature is 70-90℃, and the stirring time is 2-4h.

[0019] In some embodiments of the present application, in S2, the heating temperature is 55-70℃, and the stirring time is 1-3h.

[0020] In a third aspect of the present application, the polyurethane adhesive of the first aspect of the present application is applied in bonding of metal materials or bonding of high molecular materials.

[0021] In some embodiments of the present application, the metal material includes aluminum, copper, stainless steel or iron.

[0022] In some embodiments of the present application, the high molecular material includes plastic or rubber.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] The polyurethane adhesive of the present application includes A component and B component; wherein the raw materials of the A component include polycarbonate diol, polytetrahydrofuran ether diol, polyoxypropylene ether diol and isocyanate; the raw materials of the B component include polycaprolactone tetrol, dimer acid polyester diol and silane coupling agent; by selecting the above specific A component and B component for matching, the obtained polyurethane adhesive has excellent comprehensive performance, including excellent low temperature resistance, high bonding strength, stable long-term storage performance, not easy to yellow, good bending resistance. DETAILED DESCRIPTION

[0025] The content of the present application is further described in detail through specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples can be obtained from conventional commercial channels, or can be obtained by existing technical methods. Unless otherwise specified, the test or test method is a conventional method in the art.

[0026] Example 1

[0027] A polyurethane adhesive comprises A component and B component; wherein the A component comprises the following raw material components by mass fraction: polycarbonate diol (number average molecular weight 2000 g / mol) 15 parts, polytetrahydrofuran ether diol (number average molecular weight 1000 g / mol) 20 parts, polypropylene oxide ether diol (number average molecular weight 2000 g / mol) 25 parts and isocyanate 70 parts; the B component comprises the following raw material components by mass fraction: polycaprolactone tetrol (number average molecular weight 1000 g / mol) 20 parts, dimer acid polyester diol (number average molecular weight 2000 g / mol) 30 parts and silane coupling agent 1.2 parts; the isocyanate is isophorone diisocyanate, and the silane coupling agent is gamma-aminopropyl triethoxysilane.

[0028] The preparation method of the polyurethane adhesive comprises the following steps:

[0029] S1, polycarbonate diol, polytetrahydrofuran ether diol, polypropylene oxide ether diol and isocyanate are mixed, stirred at 80 DEG C under nitrogen protection for 3h, vacuum degassing to obtain A component;

[0030] S2, polycaprolactone tetrol, dimer acid polyester diol and silane coupling agent are mixed, stirred at 65 DEG C for 2h, vacuum degassing to obtain B component;

[0031] S3, A component and B component are mixed in a mass ratio of 1.5:1 to obtain a polyurethane adhesive.

[0032] Example 2 (raw material types are the same as example 1, and the amount is different)

[0033] A polyurethane adhesive comprises A component and B component; wherein the A component comprises the following raw material components by mass fraction: polycarbonate diol 10 parts, polytetrahydrofuran ether diol 15 parts, polypropylene oxide ether diol 20 parts and isocyanate 50 parts; the B component comprises the following raw material components by mass fraction: polycaprolactone tetrol 15 parts, dimer acid polyester diol 20 parts and silane coupling agent 0.5 parts; the isocyanate is isophorone diisocyanate, and the silane coupling agent is gamma-aminopropyl triethoxysilane.

[0034] The preparation method of the polyurethane adhesive comprises the following steps:

[0035] S1, polycarbonate diol, polytetrahydrofuran ether diol, polypropylene oxide ether diol and isocyanate are mixed, stirred at 80 DEG C under nitrogen protection for 3h, vacuum degassing to obtain A component;

[0036] S2, polycaprolactone tetrol, dimer acid polyester diol and silane coupling agent are mixed, stirred at 65 DEG C for 2h, vacuum degassing to obtain B component;

[0037] S3, mixing the A component and the B component according to a mass ratio of 1.2:1 to obtain the polyurethane adhesive.

[0038] Example 3 (raw material types are the same as Example 1, and the amount is different)

[0039] A polyurethane adhesive comprises an A component and a B component; wherein the A component comprises the following raw material components in parts by mass: polycarbonate diol 20 parts, polytetrahydrofuran ether diol 30 parts, polypropylene oxide ether diol 30 parts, and isocyanate 80 parts; the B component comprises the following raw material components in parts by mass: polycaprolactone tetrol 25 parts, dimer acid polyester diol 40 parts, and silane coupling agent 1.5 parts; the isocyanate is isophorone diisocyanate, and the silane coupling agent is γ-aminopropyl triethoxysilane.

[0040] The preparation method of the polyurethane adhesive comprises the following steps:

[0041] S1, mixing polycarbonate diol, polytetrahydrofuran ether diol, polypropylene oxide ether diol, and isocyanate, stirring at 80°C under nitrogen protection for 3h, and vacuum degassing to obtain the A component;

[0042] S2, mixing polycaprolactone tetrol, dimer acid polyester diol, and silane coupling agent, stirring at 65°C for 2h, and vacuum degassing to obtain the B component;

[0043] S3, mixing the A component and the B component according to a mass ratio of 1.8:1 to obtain the polyurethane adhesive.

[0044] Comparative Example 1

[0045] The difference from Example 1 is that the polycarbonate diol is replaced by an equal amount of polytetrahydrofuran ether diol, i.e., the polytetrahydrofuran ether diol is 35 parts, and the rest of the raw materials, the amount, and the preparation method are the same as Example 1.

[0046] Comparative Example 2

[0047] The difference from Example 1 is that the polypropylene oxide ether diol is replaced by an equal amount of polytetrahydrofuran ether diol, i.e., the polytetrahydrofuran ether diol is 45 parts, and the rest of the raw materials, the amount, and the preparation method are the same as Example 1.

[0048] Comparative Example 3

[0049] The difference from Example 1 is that the polycaprolactone tetrol is replaced by an equal amount of dimer acid polyester diol, i.e., the dimer acid polyester diol is 50 parts, and the rest of the raw materials, the amount, and the preparation method are the same as Example 1.

[0050] Comparative Example 4

[0051] The difference from Example 1 is that the dimer acid polyester diol is replaced by polycaprolactone tetrol in equal amount, i.e. 50 parts of polycaprolactone tetrol, and the rest of raw materials, amount and preparation method are the same as those in Example 1.

[0052] Performance test of polyurethane adhesive

[0053] Shear strength: the shear strength is tested according to the method in GB / T 7124-2008 Adhesives - Determination of tensile shear strength (rigid material to rigid material).

[0054] Bending resistance: detected according to GB / T 3903.1-2017 Test methods for shoes - Resistance to folding of whole shoes.

[0055] Anti-yellowing property: detected according to GB / T 39294-2020 Determination of discoloration (yellowing) property of adhesives.

[0056] The performance test results are shown in Table 1.

[0057] Table 1

[0058] Test Group Shear strength at 25°C (MPa) Bending resistance Anti-yellowing Example 1 15.8 80,000 times Color card 5 levels Example 2 14.6 80,000 times Color card 5 levels Example 3 15.3 80,000 times Color card 5 levels Comparative Example 1 12.4 60,000 times Color card 4 levels Comparative Example 2 11.6 60,000 times Color card 4 levels Comparative Example 3 11.1 60,000 times Color card 4 levels Comparative Example 4 12.2 60,000 times Color card 4 levels

[0059] In addition, the performance test results of the sample after storage at-50℃ for 90 days are shown in Table 2.

[0060] Table 2

[0061] Test Group Shear strength (MPa) Bending resistance Anti-yellowing Example 1 15.2 80,000 times Color card 5 levels Example 2 14.1 80,000 times Color card 5 levels Example 3 14.6 80,000 times Color card 5 levels Comparative Example 1 10.5 50,000 times Color card 3 levels Comparative Example 2 9.4 50,000 times Color card 3 levels Comparative Example 3 8.7 50,000 times Color card 3 levels Comparative Example 4 10.4 50,000 times Color card 3 levels

[0062] According to the data in Table 1 and Table 2, it can be seen that the polyurethane adhesives provided by Examples 1-3 have excellent comprehensive performance, not only high bonding strength, but also basically unchanged performance after long-term storage at low temperature, and good anti-yellowing property. The polyurethane adhesives provided by Comparative Examples 1-4 have relatively low bonding strength, and also have general performance in terms of low-temperature resistance, bending resistance and anti-yellowing property.

[0063] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the described embodiments, and those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present application. These equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A polyurethane adhesive, characterized in that: The polyurethane adhesive comprises component A and component B; the raw materials of component A comprise polycarbonate diol, polytetramethylene ether diol, polyoxypropylene ether diol and isocyanate; the raw materials of component B comprise polycaprolactone tetraol, dimer acid polyester diol and silane coupling agent.

2. The polyurethane adhesive according to claim 1, characterized in that The mass ratio of component A to component B is (1.2-1.8):

1.

3. The polyurethane adhesive according to claim 1, characterized in that In parts by mass, the raw materials of component A include 10-20 parts of polycarbonate diol, 15-30 parts of polytetramethylene ether diol, 20-30 parts of polyoxypropylene ether diol and 50-80 parts of isocyanate.

4. The polyurethane adhesive according to claim 1, characterized in that Calculated by mass, the raw materials of the B component include 15-25 parts of polycaprolactone tetraol, 20-40 parts of dimer acid polyester diol and 0.5-1.5 parts of silane coupling agent.

5. The polyurethane adhesive according to claim 1, characterized in that The isocyanate includes at least one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and diphenylmethane diisocyanate.

6. The polyurethane adhesive according to claim 1, characterized in that The silane coupling agent includes at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane and γ-(2,3-epoxypropyloxy)propyltrimethoxysilane.

7. The method for preparing the polyurethane adhesive according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, mixing the polycarbonate diol, polytetramethylene ether diol, polyoxypropylene ether diol and isocyanate, heating and stirring to obtain the A component; S2, mixing the polycaprolactone tetraol, dimer acid polyester diol and silane coupling agent, heating and stirring to obtain the B component; S3. Mixing the component A and the component B to obtain the polyurethane adhesive.

8. The preparation method according to claim 7, characterized in that In S1, the heating temperature is 70-90° C., and the stirring time is 2-4 h.

9. The preparation method according to claim 7, characterized in that In S2, the heating temperature is 55-70° C., and the stirring time is 1-3 h.

10. Use of the polyurethane adhesive according to any one of claims 1 to 6 in bonding metal materials or polymer materials.