Moisture-cured single-component polyurethane structural adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of a single-component polyurethane adhesive, and relates to a reactive moisture-curable single-component polyurethane structural adhesive capable of being applied at normal temperature and a preparation method of the reactive moisture-curable single-component polyurethane structural adhesive. According to the prepared single-component polyurethane structural adhesive, the tedious process of heating and sizing a conventional moisture curing polyurethane hot melt adhesive is omitted, so that the single-component polyurethane structural adhesive is convenient to use; compared with the prior art, the polyurethane adhesive has the advantages that the characteristic of high reliability of the polyurethane adhesive is considered, certain initial curing strength can be achieved in a short time, the transfer and process requirements are met, in addition, heating curing is not needed, the good bonding capacity for PC materials is achieved, and the bonding requirements in multiple scenes can be met.

Description

Technical Field

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

[0002] With the progress of society, technological iteration, and the discovery of various materials and technologies, seemingly impossible but eventually achievable problems have been gradually solved one after another. In the field of adhesives alone, there are many different adhesive systems, such as epoxy, acrylic, polyurethane, and UV, each with its own merits. Polyurethane system glue, from the earliest two-component polyurethane structural adhesive to the later reactive polyurethane hot melt adhesive, the emergence of each product has solved customer problems and met market demand.

[0003] Polyurethane two-component structural adhesive, while taking into account excellent bonding strength, has the characteristics of low cost and versatility by adding thermal conductive materials, pigments and fillers, etc., but the component ratio requirements are strict, and poor bonding due to ratio problems is prone to occur during use. As a single-component glue, reactive polyurethane hot melt adhesive avoids the problem of poor bonding caused by ratio problems, but it needs to be heated and melted before it can be used, which invisibly prolongs the process time and increases the cost of use, and is also unfriendly to non-corporate users. On this basis, the development of a portable single-component room-temperature glue that does not require heating and curing and has the stability of polyurethane bonding has a good market prospect under the current circumstances. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a single-component polyurethane structural adhesive that is cured by dispensing at room temperature and moisture, and a preparation method thereof.

[0005] The specific technical solutions of the present invention are as follows:

[0006] The object of the present invention is to provide a moisture-cured one-component polyurethane structural adhesive, comprising the following components in parts by weight:

[0007] 40-60 parts of high molecular weight trifunctional polyether polyol, 3-5 parts of crystalline bifunctional polyester polyol, 0.5-1 parts of stabilizer, 0.1-1 parts of defoamer, 40-70 parts of polyisocyanate, 0.2-1 parts of silane coupling agent, and 0.3-1 parts of catalyst.

[0008] Furthermore, the crystalline bifunctional polyester polyol is one or two of Evonik's 7360, 7380 or 7330.

[0009] Furthermore, the high molecular weight trifunctional polyether polyol is 3600H from Shangzheng New Materials, a trifunctional epoxy-terminated product with a molecular weight of 6000.

[0010] Further, the stabilizer is one or two of phosphoric acid or antioxidant 1010;

[0011] Further, the defoamer is one of BASF EFKA SI 2038 or Deqian 5500;

[0012] Further, the polyisocyanate is a carbodiimide-modified MDI with a functionality of 2.2;

[0013] Furthermore, the silane coupling agent is one or both of KH550 and KH590;

[0014] Furthermore, the catalyst is one or two of dibutyltin dilaurate, stannous octoate, and triethylenediamine.

[0015] The preparation method of the moisture-curing single-component polyurethane structural adhesive comprises the following steps: controlling the ambient humidity to be below 40%, weighing a high molecular weight trifunctional polyether polyol, a crystalline bifunctional polyester polyol, a reaction stabilizer, a heat stabilizer and a defoaming agent in proportion and adding them into a stirring kettle, dehydrating at a high temperature of 120-140 DEG C for 1-3 hours, cooling to 60-80 DEG C, adding isocyanate under stirring in a nitrogen atmosphere, continuing vacuum dispersion at 100-120 DEG C for 1-2 hours, finally adding a catalyst, continuing vacuum dispersion for 0.5-1 hour, breaking the vacuum with nitrogen, discharging the materials, and sealing and packaging to obtain the moisture-curing single-component polyurethane structural adhesive.

[0016] The beneficial effects of the present invention are: through the cross-linking reaction of trifunctional polyol and polyisocyanate, a dense polymer film can be formed in a short time, and by adding crystalline polyester polyol, the film-forming time is further shortened, so that the glue can form a film within 20 minutes at room temperature, and generate sufficient initial bonding force, so that the sample can be transferred, and at the same time, a high bonding strength can be obtained for PC material at 24 hours. In addition, by increasing the molar ratio (R value) of isocyanate group to hydroxyl group, more NCO groups exist in a free form, and the viscosity of the product is diluted in disguise, so that the product has a lower viscosity at room temperature (can reach 15000cps and below at 25°C), and room temperature dispensing is realized. DETAILED DESCRIPTION

[0017] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0018] Embodiment 1:

[0019] Preparation of low viscosity moisture curing polyurethane structural adhesive:

[0020] 30g of crystalline difunctional polyester polyol (Evonik 7330) and 480g of high molecular weight trifunctional polyether polyol (Shangzheng New Materials 3600H), 5g of stabilizer (phosphoric acid), and 1g of defoamer (Deqian 5500) were pre-dispersed and dehydrated at 130°C / 2h in vacuum for use, cooled to 80°C, 485.3g of carbodiimide-modified MDI was added under stirring in a nitrogen atmosphere, heated to 120°C, and the vacuum dispersion reaction was continued for 60min. Then 3g of silane coupling agent (KH590) and 5g of catalyst DMDEE were added and the vacuum dispersion reaction was continued for 60min. The vacuum was broken with nitrogen, the material was discharged, and sealed and packaged to obtain a one-component moisture-curable polyurethane structural adhesive.

[0021] Comparative Example 1:

[0022] Preparation of low viscosity moisture curing polyurethane structural adhesive:

[0023] 30g of crystalline difunctional polyester polyol (Evonik 7330) and 480g of high molecular weight trifunctional polyether polyol (Bluestar Dongda EP330NG), 5g of stabilizer (phosphoric acid), and 1g of defoamer (Deqian 5500) were pre-dispersed and dehydrated at 130°C / 2h in vacuum for use, cooled to 80°C, 564.3g of carbodiimide-modified MDI was added under stirring in a nitrogen atmosphere, heated to 120°C, and the vacuum dispersion reaction was continued for 60min. Then 3g of silane coupling agent (KH590) and 5g of catalyst DMDEE were added and the vacuum dispersion reaction was continued for 60min. The vacuum was broken with nitrogen, the material was discharged, and sealed and packaged to obtain a single-component moisture-curable polyurethane structural adhesive.

[0024] Comparative Example 2:

[0025] Preparation of low viscosity moisture curing polyurethane structural adhesive:

[0026] 30g of crystalline difunctional polyester polyol (Evonik 7330) and 300g of low molecular weight difunctional polyether polyol (Shangzheng New Materials DDL-2000D), 5g of stabilizer (phosphoric acid), and 1g of defoamer (Deqian 5500) were pre-dispersed and dehydrated at 130°C / 2h in vacuum for use, cooled to 80°C, and 597.5g of carbodiimide-modified MDI was added under stirring in a nitrogen atmosphere. The mixture was heated to 120°C and the vacuum dispersion reaction was continued for 60min. Then 3g of silane coupling agent (KH590) and 5g of catalyst DMDEE were added and the vacuum dispersion reaction was continued for 60min. The vacuum was broken with nitrogen, the material was discharged, and sealed and packaged to obtain a one-component moisture-curable polyurethane structural adhesive.

[0027] Comparative Example 3:

[0028] Preparation of low viscosity moisture curing polyurethane structural adhesive:

[0029] 30g of crystalline difunctional polyester polyol (Evonik 7330) and 480g of high molecular weight trifunctional polyether polyol (Shangzheng New Materials 3600H), 5g of stabilizer (phosphoric acid), and 1g of defoamer (Deqian 5500) were pre-dispersed and dehydrated at 130°C / 2h in vacuum for use, cooled to 80°C, 419.3g of MDI was added under stirring in a nitrogen atmosphere, heated to 120°C, and the vacuum dispersion reaction was continued for 60min. Then 3g of silane coupling agent (KH590) and 5g of catalyst DMDEE were added and the vacuum dispersion reaction was continued for 60min. The vacuum was broken with nitrogen, the material was discharged, and sealed and packaged to obtain a one-component moisture-curable polyurethane structural adhesive.

[0030] Comparative Example 4:

[0031] Preparation of low viscosity moisture curing polyurethane structural adhesive:

[0032] 480g of high molecular weight trifunctional polyether polyol (Shangzheng New Material 3600H), 5g of stabilizer (phosphoric acid), and 1g of defoamer (Deqian 5500) were pre-dispersed and dehydrated at 130℃ / 2h in vacuum for use, cooled to 80℃, 453.0g of carbodiimide modified MDI was added under stirring in a nitrogen atmosphere, heated to 120℃, and the vacuum dispersion reaction was continued for 60min. Then 3g of silane coupling agent (KH590) and 5g of catalyst DMDEE were added and the vacuum dispersion reaction was continued for 60min. The vacuum was broken with nitrogen, the material was discharged, and sealed and packaged to obtain a one-component moisture-curable polyurethane structural adhesive.

[0033] The present invention needs to carry out the following performance tests:

[0034] 1. Samples, substrates and curing conditions

[0035] Selected substrate: PC vs PC;

[0036] Shear strength test: 3mm diameter dot;

[0037] Colloid thickness: 0.15mm;

[0038] Pressing area 25*5mm;

[0039] Stretching speed: 10mm / min;

[0040] Curing conditions: 25°C, 50% RH for 20 min or 24 h;

[0041] Test environment temperature: 25℃.

[0042] 2. Strength test

[0043] Prepolymer shear strength: Apply a 3mm diameter glue dot to the substrate surface, add a 0.15mm gap sheet, press on the second sheet, use a 1kg weight to press for 20 minutes, and use a tensile testing machine to test the shear strength.

[0044] Shear strength of structural adhesive: Apply a 3mm diameter glue dot to the surface of the substrate, add a 0.15mm gap sheet, press on the second sheet, use a 1kg weight to press for 10s, remove the weight, put the sample into a 90℃ oven to cure for 30min, take it out and cool it to room temperature before measuring.

[0045] 3. Viscosity test

[0046] Instrument used: Haake RS6000 rheometer

[0047] Use rotor: C20 rotor

[0048] Speed: 10 -1 rpm -1

[0049] The information of different structural adhesives obtained in the present invention and their test results are summarized in Table 1

[0050] Table 1. Special structural materials used in structural adhesives with different numbers and test results

[0051]

[0052]

[0053] It can be seen from the results in Table 1 that in the present invention, through the data of the embodiments and comparative examples, it is found that the viscosity of the obtained structural adhesive is relatively low, and the requirements for room temperature dispensing can be achieved. From the perspective of 20min shear strength, the influence of different structures is as follows: trifunctional polyol and isocyanate reaction crosslinking effect > epoxy end-capping structure > crystalline polyester polyol. The crosslinking effect is obvious in 20min film-forming effect. Since the amount of crystalline polyester polyol added is small, the effect on the initial solid strength is small. From the perspective of 24h shear strength, the influence of different structures is as follows: trifunctional polyol and isocyanate reaction crosslinking effect > crystalline polyester polyol > epoxy end-capping structure. For long-term bonding strength, polyester polyol is better than polyether polyol. Although the amount added is small, for the overall bonding, it can improve the bulk strength and bonding performance of the structural adhesive.

[0054] The low-viscosity one-component thermosetting polyurethane structural adhesive prepared in the present invention has both high bonding strength to PC and the convenience of being applied at room temperature and low pressure of 0.4MPa (can also be applied by hand), which can meet the needs of non-continuous and small-scale operations, and has the characteristics of high reliability of polyurethane structural adhesive. Therefore, it has a good market in the field of electronic packaging, mobile phone repair, home and other scenarios.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A moisture-curing one-component polyurethane structural adhesive, characterized in that: The invention comprises the following components in parts by weight: 40-60 parts of high molecular weight trifunctional polyether polyol, 3-5 parts of crystalline bifunctional polyester polyol, 0.5-1 part of stabilizer, 0.1-1 part of defoamer, 40-70 parts of polyisocyanate, 0.2-1 part of silane coupling agent and 0.3-1 part of catalyst.

2. The moisture-curing one-component polyurethane structural adhesive according to claim 1, characterized in that: The trifunctional high molecular weight polyether polyol is 3600H from Shangzheng New Materials, with a molecular weight of 6000 and trifunctional epoxy end-capping.

3. The moisture-curing one-component polyurethane structural adhesive according to claim 1, characterized in that: The crystalline bifunctional polyester polyol is one of Evonik's 7360, Evonik's 7330 and Evonik's 7380.

4. The moisture-curing one-component polyurethane structural adhesive according to claim 1, characterized in that: The polyisocyanate is a carbodiimide-modified MDI with a functionality of 2.

2.

5. The moisture-curing one-component polyurethane structural adhesive according to claim 1, characterized in that: The stabilizer is one or both of phosphoric acid and antioxidant 1010; the defoamer is one of BASF EFKA SI 2038 or Deqian 5500; the silane coupling agent is one of KH550 and Momentive A189; the catalyst includes one or both of dibutyltin disilicate, stannous octoate and triethylenediamine.

6. The preparation method of the moisture-curing one-component polyurethane structural adhesive according to claim 1 is as follows: when the ambient humidity is below 40%, a high molecular weight trifunctional polyether polyol, a crystalline bifunctional polyester polyol, a reaction stabilizer, a heat stabilizer, and a defoaming agent are weighed in proportion and added to a stirring kettle, dehydrated at a high temperature of 120-140° C. for 1-3 hours, cooled to 60-80° C., and isocyanate is added under stirring in a nitrogen atmosphere, and vacuum dispersion is continued at 100-120° C. for 1-2 hours, and finally a catalyst is added, and vacuum dispersion is continued for 0.5-1 hour, the vacuum is broken with nitrogen, the material is discharged, and sealed and packaged to obtain the moisture-curing one-component polyurethane structural adhesive.

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