Low-hardness UV moisture dual-curing reactive polyurethane hot melt adhesive

Abstract

The invention discloses a low-hardness UV (ultraviolet) moisture dual-curing reactive polyurethane hot melt adhesive which comprises the following components in parts by weight: 10-50 parts of a moisture-curable component A, 30-70 parts of a UV curing oligomer component B, 2-50 parts of an acrylate monomer, 0.5-5 parts of a photoinitiator, 0.1-1 part of a catalyst, auxiliaries and the like. According to the invention, the above components are mixed, such that the hardness is less than 50A, and the shear strength is greater than or equal to 3MPa; and consumer electronics bonding use is met.

Description

Technical Field

[0001] The invention relates to the field of hot melt adhesives, in particular to a low-hardness UV-moisture dual-curing reactive polyurethane hot melt adhesive. Background Art

[0002] Hot melt adhesive compositions are solid at room temperature, but melt into liquid when heated, and they are applied to the substrate in this molten form. When cooled, the adhesive returns to a solid state. The cooled adhesive composition has good initial bonding properties. Before solidification, the composition will remain thermoplastic and can be re-melted and re-solidified. When the adhesive composition is exposed to appropriate conditions for a period of time, chemical cross-linking occurs and the reaction solidifies, giving the final bonding properties and forming a polyurethane solid with good cohesion (strength, toughness, creep resistance and heat resistance). In the field of adhesives, moisture-curing hot melt adhesives are very important and have grown rapidly in recent years. However, polyurethane hot melt adhesives have high-temperature dispensing and the curing speed is not as fast as UV glue.

[0003] The application of low-hardness adhesives in consumer electronic products has significant advantages. Taking the buffer support agent under the screen as an example, low-hardness adhesives can successfully replace traditional foam tapes and provide a more uniform and reliable support effect. This not only reduces product quality problems that may be caused by insufficient lamination accuracy, but also fully realizes the automation of the production line, thereby greatly improving production efficiency and reducing labor costs. At the same time, the elasticity and buffering properties of low-hardness (<50A) adhesives can effectively absorb shock and vibration, protecting fragile components such as screens from damage.

[0004] In small consumer electronic products such as headphones and smart watches, low hardness (<50A) adhesives can be used to fix flexible device circuits (FPCs), providing stable bonding without causing excessive errors to sensitive circuits.

[0005] Products with high hardness (above 60A) are very likely to have light or dark lines when used as screen backing supports, which affects the display effect and is difficult to meet the application needs in some scenarios. Products with low hardness (<50A) have excellent buffering properties and can reduce the impact of impact on the screen. Summary of the invention

[0006] The invention discloses a low-hardness UV moisture dual-curing reactive polyurethane hot melt adhesive, which comprises the following components by weight: 10-50 parts of a moisture-curable component A, 30-70 parts of a UV-curable oligomer component B, 2-50 parts of an acrylate monomer, 0.5-5 parts of a photoinitiator, 0.1-1 parts of a catalyst, and auxiliary agents.

[0007] The preparation method of the moisture-curable component A is as follows: 20-60 parts of polyester polyol and 10-30 parts of polyether polyol are dehydrated and vacuumed at 110-140° C. for 3 hours. Then the temperature is lowered to 70-90° C., the vacuum is broken with nitrogen, 5-20 parts of diisocyanate are added, the temperature is raised to 90-120° C., the reaction is continued under vacuum for 60-120 minutes, the vacuum is broken with nitrogen, and the material is discharged.

[0008] The preparation method of the UV curable oligomer component B is as follows: 60-90 parts of polyether polyol are dehydrated and vacuumed at 110-140° C. for 3 hours. Then the temperature is lowered to 70-90° C., the vacuum is broken with nitrogen, 5-10 parts of diisocyanate are added, the temperature is raised to 90-120° C., the reaction is continued under vacuum for 60-120 minutes, the reaction temperature is lowered to 100° C., 2-20 parts of hydroxyl-containing acrylate are added, the reaction is continued for 2 hours, and the material is discharged.

[0009] The polyester polyol is one or more of PRIPLAST 3162, PRIPLAST 3172, and PRIPLAST 3196;

[0010] The polyether polyol is PPG2000, PPG4000, PPG6000, PPG8000, etc.

[0011] The diisocyanate is selected from MDI, liquid MDI, etc.;

[0012] The hydroxyl-containing acrylate is hydroxyethyl methacrylate or hydroxyethyl acrylate.

[0013] The acrylic acid ester monomers include but are not limited to butyl acrylate, lauryl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, isobornyl methacrylate, tetrahydrofuranyl acrylate, glycidyl methacrylate, etc.;

[0014] The photoinitiator includes but is not limited to TPO, 819, 907, 369, 184, 1172, etc.;

[0015] The catalyst is DMDEE, which is a catalyst for catalyzing the reaction between isocyanate and water;

[0016] The beneficial effects of the present invention are as follows: the hardness and initial strength are ensured by using the moisture-curing component and the UV-curing oligomer component in combination; the cross-linking density is further adjusted by strictly limiting the amount of diisocyanate added in the formula, thereby reducing the hardness; the polyurethane acrylate prepared with polyether polyol as the main body has flexible segments and flexible groups that can improve the viscosity and bonding strength of the system; the hardness of the product prepared by the combination of the components can reach below 50A, and the shear strength is ≥3MPa. DETAILED DESCRIPTION

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

[0018] A method for preparing a moisture-curable component A, comprising the following steps:

[0019] Moisture curing component A-1

[0020] In a 250ml three-necked reaction bottle, add 50g DYNACOLL 7362 and 35g PPG-6000, dry under reduced pressure at 140°C for 2h, lower the temperature to 90°C, add 13.5g MDI, raise the temperature to 110°C, react for 90min, and the product is obtained.

[0021] Moisture curing component A-2

[0022] In a 250ml three-necked reaction bottle, add 50g PRIPLAST 3196 and 35g PPG-6000, dry under reduced pressure at 140°C for 2h, lower the temperature to 90°C, add 11.3g MDI, raise the temperature to 110°C, react for 90min, and the product is obtained.

[0023] A method for preparing a polyurethane acrylate oligomer component B comprises the following steps:

[0024] UV curable oligomer component B-1

[0025] In a 250ml three-necked reaction bottle, add 80g PPG-2000, dry under reduced pressure at 140℃ for 2h, lower the temperature to 90℃, add 20g MDI, raise the temperature to 110℃, react for 90min, lower the temperature by 90℃, add 10.75g HEMA, continue to react for 90min, and the material is obtained.

[0026] UV curable oligomer component B-2

[0027] In a 250ml three-necked reaction bottle, add 80g PPG-4000, dry under reduced pressure at 140℃ for 2h, lower the temperature to 90℃, add 10g MDI, raise the temperature to 110℃, react for 90min, lower the temperature by 90℃, add 5.4g HEMA, continue to react for 90min, and the material is obtained.

[0028] UV curable oligomer component B-3

[0029] In a 250ml three-necked reaction bottle, add 80g PPG-6000, dry under reduced pressure at 140°C for 2h, lower the temperature to 90°C, add 5g MDI, raise the temperature to 110°C, react for 90min, lower the temperature by 90°C, add 2.7g hydroxy acrylate (HEMA), continue to react for 90min, and the material is obtained.

[0030] Prepare according to the following proportions and conduct tests;

[0031] Components Example 1 Example 2 Comparative Example 1 Comparative Example 2 A-1 0 0 20 0 A-2 20 20 0 20 B-1 0 0 0 50 B-2 50 0 0 0 B-3 0 50 50 0 IBOA 30 30 30 30 DMDEE 1 1 1 1 TPO 1 1 1 1

[0032] The hot melt adhesives obtained in Examples 1-2 and Comparative Examples were tested as follows:

[0033] 1. Hardness

[0034] 0.2 mm thick films were prepared and cured at 25°C / 50% for 7 days. TA DMA equipment was used for testing.

[0035] 2. Shear strength

[0036] Apply glue on the PC surface, adjust the amount of glue, use a gap sheet to control the gap to 0.15mm thickness, and the glue pressing size to 25mm*1mm*0.15mm. Curing for 24 hours in an environment of 25℃ and 50% humidity.

[0037] 3. Strength test method

[0038] The test specimens were subjected to strength tests using a universal tensile testing machine.

[0039] The test results are shown in Table 1.

[0040] Table 1. Test results

[0041]

[0042] 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 low-hardness UV moisture dual-curing reactive polyurethane hot melt adhesive, comprising the following components by weight: 10-50 parts of moisture-curable component A, 30-70 parts of UV-curable oligomer component B, 2-50 parts of acrylate monomers, 0.5-5 parts of photoinitiator, and 0.1-1 parts of catalyst.

2. A low-hardness UV-moisture dual-curing reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The preparation method of the moisture-curable component A is as follows: 20-60 parts of polyester polyol and 10-30 parts of polyether polyol are dehydrated and vacuumed at 110-140° C. for 3 hours; then the temperature is lowered to 70-90° C., the vacuum is broken with nitrogen, 5-20 parts of diisocyanate are added, the temperature is raised to 90-120° C., the reaction is continued under vacuum for 60-120 minutes, the vacuum is broken with nitrogen, and the material is discharged.

3. A low-hardness UV moisture dual-curing reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The preparation method of the UV curable oligomer component B is as follows: 60-90 parts of polyether polyol are dehydrated and vacuumed at 110-140° C. for 3 hours; then the temperature is lowered to 70-90° C., the vacuum is broken with nitrogen, 5-10 parts of diisocyanate are added, the temperature is raised to 90-120° C., the reaction is continued under vacuum for 60-120 minutes, the reaction temperature is lowered to 100° C., 2-20 parts of hydroxyl-containing acrylate are added, the reaction is continued for 2 hours, and the material is discharged.

4. A low-hardness UV-moisture dual-curing reactive polyurethane hot melt adhesive according to claim 2, characterized in that: The polyester polyol is one or more of PRIPLAST 3162, PRIPLAST 3172, and PRIPLAST 3196.

5. A low-hardness UV-moisture dual-curing reactive polyurethane hot melt adhesive according to claim 2 or 3, characterized in that: The polyether polyol is PPG2000, PPG4000, PPG6000, PPG8000; the diisocyanate is selected from MDI and liquid MDI.

6. A low-hardness UV-moisture dual-curing reactive polyurethane hot melt adhesive according to claim 3, characterized in that: The hydroxyl-containing acrylate is hydroxyethyl methacrylate or hydroxyethyl acrylate.

7. The low-hardness UV-moisture dual-curing reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The acrylate monomer includes one of butyl acrylate, lauryl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, isobornyl methacrylate, tetrahydrofuran acrylate, and glycidyl methacrylate; the photoinitiator includes one of TPO, 819, 907, 369, 184, and 1172.

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