Polyurethane adhesive and preparation method thereof

Abstract

The invention provides a polyurethane adhesive and a preparation method thereof, and the polyurethane adhesive comprises the following components by weight: 30-50 parts of polyether polyol; 20 to 30 parts of isocyanate; 0.5 to 1 part of a catalyst; 1-2 parts of an antioxidant; 10 to 15 parts of sodium bentonite; 1 to 3 parts of n-pentane; and 40-60 parts of water. Due to the fact that the thickness of the adhesive is increased due to micro-expansion after the adhesive is smeared, the two base materials need to be pressed in the bonding process, the adhesive is pressed to be thin again in the bonding process, and the adhesive of the expanded part has the chance to deform towards a gap to fill an unbonded area; in the bonding process, the two base materials need to be pressed to thin the bonding agent, and a user can directly feel the bonding process through force application and the thickness change of the bonding agent; in addition, when the bonding surfaces of the two base materials are not completely matched, the micro-expansion of the bonding agent can also fill the unmatched area, so that a more sufficient bonding effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a polyurethane adhesive and a preparation method thereof. Background Art

[0002] As a typical synthetic polymer material, polyurethane adhesive has unique corrosion resistance, hydrolysis resistance, bending resistance and excellent thermal adhesion. Its structure contains both carbonyl and amino groups, which can interact with many polar groups to form hydrogen bonds, so it has excellent adsorption and adhesion. Its performance and environmental advantages make it the leader among many adhesives. The preparation and processing technology of polyurethane adhesives has been developed to date, and its application areas include clothing, footwear, automobiles, sanitary products, packaging, electronics and many other fields.

[0003] Polyurethane adhesives basically rely on application when used, but the application process may be uneven, which will result in unbonded areas on the bonding surfaces of the two substrates, thereby affecting the bonding strength. Summary of the invention

[0004] In view of the above technical problems, this application proposes a polyurethane adhesive and a preparation method. The specific technical solutions are as follows:

[0005] On the one hand, the present application provides a polyurethane adhesive, comprising the following components in parts by weight:

[0006] 30-50 parts of polyether polyol;

[0007] 20-30 parts of isocyanate;

[0008] 0.5-1 part of catalyst;

[0009] 1-2 parts of antioxidant;

[0010] 10-15 parts of sodium bentonite;

[0011] 1 to 3 parts of n-pentane;

[0012] 40-60 parts of water.

[0013] Preferably, the polyether polyol is one or more of glyceryl polyether polyol, trimethylolpropane polyether, sucrose polyether polyol, and sorbitol polyether polyol.

[0014] Preferably, the isocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

[0015] Preferably, the catalyst is one or more of dimethylethanolamine, triethylenediamine, diazabicycloundecene, and dimethylcyclohexylamine.

[0016] Preferably, the antioxidant is one or more of antioxidant 1010, antioxidant 1024, and antioxidant 168.

[0017] On the other hand, the present application provides a method for preparing a polyurethane adhesive, the method comprising:

[0018] Vacuum dehydrate the polyether polyol at 100-120°C for 1.5-2.0h, and cool to 45-55°C;

[0019] Add isocyanate and heat to 80-90°C for reaction for 2.5-3h, then cool to 50-70°C;

[0020] Add catalyst, antioxidant, water and sodium bentonite and react for 1 to 1.5 hours;

[0021] Inject n-pentane into the reacted material under sealed conditions and store it in a sealed state at low temperature.

[0022] The beneficial effects of the present invention are:

[0023] (1) Avoid uneven application of adhesive, resulting in unbonded areas on the bonding surfaces of the two substrates, which will affect the bonding strength. Specifically, since the thickness of the adhesive will increase due to micro-expansion after application, the two substrates need to be pressed together during bonding. During this process, the adhesive will be thinned again, so that the expanded part of the adhesive has the opportunity to deform into the gap and fill the unbonded area;

[0024] (2) Providing a better user experience. The thickness of traditional adhesives remains almost unchanged after application, so it is difficult to perceive the bonding process and bonding effect when two substrates are bonded. However, the thickness of the adhesive of the present application will increase due to micro-expansion after application. During the bonding process, the two substrates need to be pressed together to make the adhesive thinner. Users can directly feel the bonding process through the force applied and the change in adhesive thickness. In addition, when the bonding surfaces of the two substrates are not completely matched, the micro-expansion of the adhesive can also fill the mismatched area to achieve a more sufficient bonding effect. DETAILED DESCRIPTION

[0025] In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments. However, it will be appreciated by those skilled in the art that the present invention may be practiced without these details. In other cases, well-known structures are not shown or described in detail to avoid unnecessarily obscuring the description of the embodiments. Unless the context otherwise requires, throughout the specification and the appended claims, the word "comprising" shall be interpreted in an open, inclusive sense, i.e., as "including but not limited to".

[0026] The present application provides a polyurethane adhesive, which comprises the following components in parts by weight:

[0027] 30-50 parts of polyether polyol;

[0028] 20-30 parts of isocyanate;

[0029] 0.5-1 part of catalyst;

[0030] 1-2 parts of antioxidant;

[0031] 10-15 parts of sodium bentonite;

[0032] 1 to 3 parts of n-pentane;

[0033] 40-60 parts of water.

[0034] Among them, the polyether polyols may include glyceryl polyether polyols, trimethylolpropane polyethers, sucrose polyether polyols, and sorbitol polyether polyols;

[0035] Isocyanates include isophorone diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate;

[0036] The catalyst may include dimethylethanolamine, triethylenediamine, diazabicycloundecene, and dimethylcyclohexylamine.

[0037] Optional antioxidants include antioxidant 1010, antioxidant 1024, and antioxidant 168.

[0038] In the present application, polyether polyol, isocyanate, catalyst, antioxidant and water are conventional ingredients that can be used to prepare polyurethane adhesive. On this basis, sodium bentonite and n-pentane are added in the present application, so that the prepared polyurethane adhesive will expand slightly to a certain extent in the early stage after being applied on the surface of the substrate, thereby increasing the thickness of the adhesive. Generally, the application thickness is 1 to 2 mm. Within 30 seconds of application, the thickness of the adhesive will increase to 2 to 4 times the original thickness due to the micro-expansion. The use characteristics are: (1) When the adhesive is unevenly applied, it is avoided that there are unbonded areas in the bonding surfaces of the two substrates, which will affect the bonding strength. Specifically, since the thickness of the adhesive increases due to the micro-expansion after application, the adhesive thickness will increase to 2 to 4 times the original thickness. In addition, the two substrates need to be pressed together during bonding, and the adhesive will be thinned again during this process, so that the expanded part of the adhesive has the opportunity to deform into the gap and fill the unbonded area; (2) providing a better user experience. The thickness of traditional adhesives is almost unchanged after application, so it is difficult to perceive the bonding process and bonding effect when the two substrates are bonded. However, the thickness of the adhesive of the present application will increase due to micro-expansion after application. During the bonding process, the two substrates need to be pressed together to thin the adhesive. The user can directly feel the bonding process through the force applied and the change in adhesive thickness. In addition, when the bonding surfaces of the two substrates are not completely matched, the micro-expansion of the adhesive can also fill the mismatched area to achieve a more sufficient bonding effect.

[0039] Example 1

[0040] The polyurethane adhesive of this embodiment includes the following components:

[0041] Polyether polyol 30kg;

[0042] Isocyanate 20kg;

[0043] Catalyst 0.5kg;

[0044] Antioxidant 1kg;

[0045] Sodium bentonite 10kg;

[0046] 1kg of n-pentane;

[0047] Water 40kg.

[0048] The polyurethane adhesive of this embodiment is prepared by the following method:

[0049] Vacuum dehydrate the polyether polyol at 100-120°C for 1.5-2.0h, and cool to 45-55°C;

[0050] Add isocyanate and heat to 80-90°C for reaction for 2.5-3h, then cool to 50-70°C;

[0051] Add catalyst, antioxidant, water and sodium bentonite and react for 1 to 1.5 hours;

[0052] Inject n-pentane into the reacted material under sealed conditions and store it in a sealed state at low temperature.

[0053] Example 2

[0054] The polyurethane adhesive of this embodiment includes the following components:

[0055] Polyether polyol 40kg;

[0056] Isocyanate 25kg;

[0057] Catalyst 0.8kg;

[0058] Antioxidant 1.5kg;

[0059] Sodium bentonite 12kg;

[0060] 2kg of n-pentane;

[0061] 50kg water.

[0062] The polyurethane adhesive of this embodiment is prepared by the following method:

[0063] Vacuum dehydrate the polyether polyol at 100-120°C for 1.5-2.0h, and cool to 45-55°C;

[0064] Add isocyanate and heat to 80-90°C for reaction for 2.5-3h, then cool to 50-70°C;

[0065] Add catalyst, antioxidant, water and sodium bentonite and react for 1 to 1.5 hours;

[0066] Inject n-pentane into the reacted material under sealed conditions and store it in a sealed state at low temperature.

[0067] Example 3

[0068] The polyurethane adhesive of this embodiment includes the following components:

[0069] Polyether polyol 50kg;

[0070] Isocyanate 30kg;

[0071] Catalyst 1kg;

[0072] Antioxidant 2kg;

[0073] Sodium bentonite 15kg;

[0074] 3kg of n-pentane;

[0075] 60kg of water.

[0076] The polyurethane adhesive of this embodiment is prepared by the following method:

[0077] Vacuum dehydrate the polyether polyol at 100-120°C for 1.5-2.0h, and cool to 45-55°C;

[0078] Add isocyanate and heat to 80-90°C for reaction for 2.5-3h, then cool to 50-70°C;

[0079] Add catalyst, antioxidant, water and sodium bentonite and react for 1 to 1.5 hours;

[0080] Inject n-pentane into the reacted material under sealed conditions and store it in a sealed state at low temperature.

[0081] Comparative Example 1

[0082] The polyurethane adhesive of this embodiment includes the following components:

[0083] Polyether polyol 30kg;

[0084] Isocyanate 20kg;

[0085] Catalyst 0.5kg;

[0086] Antioxidant 1kg;

[0087] Water 40kg.

[0088] The polyurethane adhesive of this embodiment is prepared by the following method:

[0089] Vacuum dehydrate the polyether polyol at 100-120°C for 1.5-2.0h, and cool to 45-55°C;

[0090] Add isocyanate and heat to 80-90°C for reaction for 2.5-3h, then cool to 50-70°C;

[0091] Add catalyst, antioxidant and water and react for 1 to 1.5 hours.

[0092] For the adhesives in Examples 1 to 3 and Comparative Example 1, the bonding strength was tested according to the method provided in the standard document with reference number GBT7124-2008. Specifically, 6061 aluminum sheet was used, and the bonding surface size was 12.5mm×25mm. After applying the waterborne polyurethane adhesive obtained in the Examples and Comparative Examples, it was activated at 80°C for 3 minutes, and then the aluminum sheet was pasted with constant pressure and placed in an oven at 80°C for 3 hours. After cooling, it was immediately tested on a computerized tensile test machine at a tensile speed of 5mm / min. Five samples were tested in each group, and the arithmetic mean was calculated to obtain the initial bonding strength. After being placed at room temperature for 3 days, it was tested on a computerized tensile test machine at a tensile speed of 5mm / min. Five samples were tested in each group, and the arithmetic mean was calculated to obtain the final bonding strength.

[0093] The test results are shown in Table 1.

[0094]

[0095] By comparison, it was found that compared with the case where no sodium bentonite and n-pentane were added, the bonding strength of Examples 1 to 3 was improved, but the improvement effect was not obvious, indicating that the addition of sodium bentonite and n-pentane would not have a negative impact on the bonding properties of the adhesive itself, but would instead have a slight strengthening effect. At the same time, the thickness of the adhesive would increase due to micro-expansion after application, thereby promoting sufficient bonding.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them.

Claims

1. A polyurethane adhesive, characterized in that: It includes the following components in parts by weight: 30-50 parts of polyether polyol; 20-30 parts of isocyanate; 0.5-1 part of catalyst; 1-2 parts of antioxidant; 10-15 parts of sodium bentonite; 1 to 3 parts of n-pentane; 40-60 parts of water.

2. The polyurethane adhesive according to claim 1, characterized in that The polyether polyol is one or more of glyceryl polyether polyol, trimethylolpropane polyether, sucrose polyether polyol and sorbitol polyether polyol.

3. The polyurethane adhesive according to claim 1, characterized in that The isocyanate is one or more of isophorone diisocyanate, hexamethylene diisocyanate, and diphenylmethane diisocyanate.

4. The polyurethane adhesive according to claim 1, characterized in that The catalyst is one or more of dimethylethanolamine, triethylenediamine, diazabicycloundecene and dimethylcyclohexylamine.

5. The polyurethane adhesive according to claim 1, characterized in that The antioxidant is one or more of antioxidant 1010 , antioxidant 1024 , and antioxidant 168 .

6. The polyurethane adhesive according to claim 1, characterized in that The preparation method of the polyurethane adhesive is: Vacuum dehydrate the polyether polyol at 100-120°C for 1.5-2.0h, and cool to 45-55°C; Add isocyanate and heat to 80-90°C for reaction for 2.5-3h, then cool to 50-70°C; Add catalyst, antioxidant, water and sodium bentonite and react for 1 to 1.5 hours; Inject n-pentane into the reacted material under sealed conditions and store it in a sealed state at low temperature.

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