Low-modulus low-hardness single-component reactive polyurethane hot melt adhesive and preparation method thereof

Abstract

The invention relates to the technical field of hot melt adhesives, in particular to a low-modulus low-hardness single-component reactive polyurethane hot melt adhesive and a preparation method thereof. The single-component reactive polyurethane hot melt adhesive provided by the invention is prepared from the following components in parts by weight: 15 to 40 parts of crystalline polyester polyol, 20 to 40 parts of liquid polyester polyol, 30 to 60 parts of polyether polyol, 0 to 1 part of monofunctional castor oil-based polyol, 0 to 10 parts of petroleum resin, 0 to 10 parts of EVA (Ethylene-Vinyl Acetate) resin, 5 to 15 parts of diisocyanate, 0 to 1 part of an auxiliary agent and 0.1 to 1 part of a catalyst, and 0-1 part of a coupling agent. The hot melt adhesive composition takes a reaction product formed by diisocyanate, polyether polyol and crystalline or non-crystalline polyester polyol as a main body, so that the hot melt adhesive composition optimally has the modulus of lower than 5MPa, the hardness of less than 30A and the shear strength of more than 1MPa, and is excellent in comprehensive performance.

Description

Technical Field

[0001] The invention relates to the technical field of hot melt adhesives, and in particular to a low-modulus and low-hardness single-component reactive polyurethane hot melt adhesive and a preparation method thereof. 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, and before solidification, the composition will remain thermoplastic and can be re-melted and re-solidified. When the adhesive composition is exposed to appropriate conditions, 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).

[0003] In the adhesive field, moisture curing hot melt adhesives are very important and have been a product that has grown rapidly in recent years. They are solvent-free and have attracted much attention due to their fast fixation, odorlessness, environmental protection, high final bonding strength, good impact resistance and flexibility, and are increasingly widely used in consumer electronics.

[0004] At present, with the gradual improvement of requirements and the upgrading of structures, in some application fields, such as screen backing support, TYPE-C charging port sealing, internal filling sealing of smart earphones, sealing and bonding of mobile phone cavities, etc., there is an increasing need for a glue with low modulus, low hardness, fast bonding strength and easy repair at room temperature.

[0005] Existing technology and experience often combine UV technology and reactive hot melt technology, with UV irradiation quickly obtaining initial solidification and subsequent slow solidification to obtain a certain degree of adhesion and hardness. However, this technology has allergic monomers and areas that are not exposed to light, which limits its use and affects its use. Although there have been certain advances in this field, there is still a need to improve the technology of reactive adhesives to expand the application of such adhesives and their application effects. Summary of the invention

[0006] In order to solve the above technical problems existing in the prior art, the present invention provides a low modulus and low hardness one-component reactive polyurethane hot melt adhesive and a preparation method thereof.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] The first aspect of the present invention is to provide a low modulus and low hardness one-component reactive polyurethane hot melt adhesive, which comprises the following components by weight: 15-40 parts of crystalline polyester polyol, 20-40 parts of liquid polyester polyol, 30-60 parts of polyether polyol, 0-1 part of monofunctional castor oil-based polyol, 0-10 parts of petroleum resin, 0-10 parts of EVA (ethylene-vinyl acetate copolymer) resin, 5-15 parts of diisocyanate, 0-1 part of auxiliary agent, 0.1-1 part of catalyst and 0-1 part of coupling agent.

[0009] The one-component reactive polyurethane hot melt adhesive provided by the present invention adds low molecular weight crystalline polyester polyol and adjusts the added amount to ensure low modulus, low hardness and high initial strength of the finally prepared one-component reactive polyurethane hot melt adhesive; a certain amount of diisocyanate is added to reduce the crosslinking density, and the hardness and modulus of the hot melt adhesive are reduced by adjusting the ratio between isocyanate and polyol; the system crosslinking degree is reduced by adding monofunctional castor oil-based polyol, and the hardness and modulus of the hot melt adhesive are reduced; the components cooperate with each other to reduce the modulus, so that the finally prepared hot melt adhesive has low modulus, low hardness and high initial adhesive strength.

[0010] On the basis of the above technical solution, the present invention can also make the following improvements:

[0011] Furthermore, the crystalline polyester polyol is selected from any one or more of DYNACOLL 7362, DYNACOLL 7390, PRIPLAST3162, PRIPLAST 3172, and PRIPLAST 3192.

[0012] The beneficial effect of adopting the above further technical solution is that the hardness and modulus of the hot melt adhesive can be further reduced by adding low-crystallinity, soft crystalline polyester polyol.

[0013] Furthermore, the isocyanate index (R value) is 1.2-1.6.

[0014] The beneficial effect of adopting the above further technical solution is that by limiting the R value within this range, the hardness and modulus of the hot melt adhesive are further reduced.

[0015] Furthermore, the liquid polyester polyol is selected from any one or more of DYNACOLL 7250, DYNACOLL 7255, and FLP2000PN.

[0016] Furthermore, the polyether polyol is selected from any one or more of PPG2000, PPG4000, PPG6000, PPG8000, PO3G2000, and PTMG2000.

[0017] Furthermore, the diisocyanate is selected from MDI or liquid MDI, and the coupling agent is selected from KH550, KH560 or KH590.

[0018] Furthermore, the auxiliary agent is antioxidant 1010.

[0019] Furthermore, the petroleum resin is Eastman resin F100.

[0020] The beneficial effect of adopting the above further technical solution is that by adding petroleum resin, the viscosity is reduced, the adhesion of the hot melt adhesive to the metal substrate is improved, and the initial bonding strength is improved.

[0021] Another aspect of the present invention is to provide a method for preparing the above-mentioned low modulus one-component reactive polyurethane hot melt adhesive, comprising the following steps: uniformly stirring crystalline polyester polyol, liquid polyester polyol, polyether polyol, petroleum resin, EVA resin, and additives in a reaction bottle, and vacuuming and dehydrating at high temperature; then cooling to a certain temperature, adding diisocyanate, heating to continue the reaction for a period of time, breaking the vacuum with nitrogen, adding monofunctional castor oil-based polyol, catalyst, and coupling agent, continuing to stir for a period of time, breaking the vacuum with nitrogen, and discharging the material to obtain the one-component reactive polyurethane hot melt adhesive.

[0022] Furthermore, the specific steps are: 15-40 parts of crystalline polyester polyol, 20-40 parts of liquid polyester polyol, 30-60 parts of polyether polyol, 0-10 parts of petroleum resin, 0-10 parts of EVA resin and 0-1 part of auxiliary agent are stirred evenly in a reaction bottle, and vacuum dehydrated at 110-140°C for 2-4 hours; then the temperature is lowered to 70-90°C, 5-15 parts of diisocyanate are added, the temperature is raised to 90-120°C, and the reaction is continued for 60-120 minutes, the vacuum is broken by nitrogen, 0-1 part of monofunctional castor oil-based polyol, 0-1 part of catalyst and 0-1 part of coupling agent are added, and the stirring is continued for 30-120 minutes, the vacuum is broken by nitrogen, and the material is discharged to obtain the one-component reactive polyurethane hot melt adhesive.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] The one-component reactive polyurethane hot melt adhesive provided by the present invention adds low molecular weight crystalline polyester polyol and adjusts the added amount to ensure low modulus, low hardness and high initial strength of the finally prepared one-component reactive polyurethane hot melt adhesive; a certain amount of diisocyanate is added to reduce the crosslinking density, and the hardness and modulus of the hot melt adhesive are reduced by adjusting the ratio between isocyanate and polyol; the system crosslinking degree is reduced by adding monofunctional castor oil-based polyol, and the hardness and modulus of the hot melt adhesive are reduced; the components cooperate with each other to reduce the modulus, so that the finally prepared hot melt adhesive has low modulus, low hardness and high initial adhesive strength. DETAILED DESCRIPTION

[0025] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0026] Example 1

[0027] In a 250 ml three-necked reaction bottle, 25 g DYNACOLL 7362, 35 g DYNACOLL 7255, 35 g PPG6000, 0.1 g antioxidant 1010 and 10 g Eastman resin F100 were added and stirred evenly. The mixture was dried under reduced pressure at 140°C for 2 h, the temperature was lowered to 90°C, 9.9 g MDI was added, the temperature was raised to 110°C, the reaction was continued for 90 min, the vacuum was broken with nitrogen, and then 0.5 g monofunctional castor oil-based polyol, 0.2 g catalyst DMDEE and 0.75 g KH590 were added. The reaction was continued with stirring for 45 min, the vacuum was broken with nitrogen, and the single-component reactive polyurethane hot melt adhesive A1 was obtained.

[0028] Example 2

[0029] In a 250 ml three-necked reaction bottle, 25 g DYNACOLL 7362, 35 g DYNACOLL 7255, 35 g PPG6000, 0.1 g antioxidant 1010 and 10 g Eastman resin F100 were added and stirred evenly. The mixture was dried under reduced pressure at 140°C for 2 h, the temperature was lowered to 90°C, 9.9 g MDI was added, the temperature was raised to 110°C, the reaction was continued for 90 min, the vacuum was broken with nitrogen, and then 1 g monofunctional castor oil-based polyol, 0.2 g catalyst DMDEE and 0.75 g KH590 were added. The reaction was continued with stirring for 45 min. The single-component reactive polyurethane hot melt adhesive A2 was obtained.

[0030] Example 3

[0031] In a 250 ml three-necked reaction bottle, 25 g DYNACOLL 7362, 35 g DYNACOLL 7255, 35 g PPG6000, 0.1 g antioxidant 1010 and 10 g Eastman resin F100 were added, and the mixture was dried under reduced pressure at 140°C for 2 h. The temperature was lowered to 90°C, 9.9 g MDI was added, the temperature was raised to 110°C, the reaction was continued for 90 min, the vacuum was broken with nitrogen, and then 0.2 g catalyst DMDEE and 0.75 g KH590 were added. The reaction was continued for 45 min, and the single-component reactive polyurethane hot melt adhesive A3 was obtained.

[0032] Example 4

[0033] In a 250 ml three-necked reaction bottle, 20 g DYNACOLL 7362, 35 g DYNACOLL 7255, 40 g PPG6000, 0.1 g antioxidant 1010 and 10 g Eastman resin F100 were added, and the mixture was dried under reduced pressure at 140 ° C for 2 h. The temperature was lowered to 90 ° C, 9.3 g MDI was added, the temperature was raised to 110 ° C, and the reaction was continued for 90 min. The vacuum was broken with nitrogen, and then 0.2 g DMDEE and 0.75 g KH590 were added as catalysts. The reaction was continued for 45 min. The single-component reactive polyurethane hot melt adhesive A4 was obtained.

[0034] Example 5

[0035] In a 250 ml three-necked reaction bottle, 15 g DYNACOLL 7362, 35 g DYNACOLL 7255, 45 g PPG-6000, 0.1 g antioxidant 1010 and 10 g Eastman resin F100 were added, and the mixture was dried under reduced pressure at 140 ° C for 2 h. The temperature was lowered to 90 ° C, 8.7 g MDI was added, and the temperature was raised to 110 ° C. The reaction was continued for 90 min, and the vacuum was broken with nitrogen. Then, 0.2 g DMDEE and 0.75 g KH590 were added as catalysts, and the reaction was continued for 45 min. The single-component reactive polyurethane hot melt adhesive A5 was obtained.

[0036] Example 6

[0037] In a 250ml three-necked reaction bottle, add 15g DYNACOLL 7362, 25g DYNACOLL 7255, 55g PPG-6000, 0.1g antioxidant 1010, and 10g Eastman resin F100, dry under reduced pressure at 140°C for 2h, lower the temperature to 90°C, add 8.3g MDI, raise the temperature to 110°C, continue to react for 90min, break the vacuum with nitrogen, then add 0.2g DMDEE and 0.75g KH590 as catalyst, continue to react for 45min, and the material is obtained.

[0038] Comparative Example 1

[0039] In a 250ml three-necked reaction bottle, add 25g DYNACOLL 7360, 35g DYNACOLL 7255, 35g PPG-2000, 0.1g antioxidant 1010, 10g Eastman resin F100, dry under reduced pressure at 140°C for 2h, lower the temperature to 90°C, add 19g MDI, raise the temperature to 110°C, react for 90min, add 0.2g DMDEE catalyst and 0.75g KH590, continue the reaction for 45min, and the product is obtained.

[0040] The hot melt adhesives obtained in Examples 1-5 and Comparative Example 1 were subjected to the following performance tests:

[0041] 1. Modulus

[0042] A 0.2 mm thick film was prepared and cured for 7 days at 25°C / 50% (temperature 25°C, humidity 50%). The test was performed using a TADMA device.

[0043] 2. Hardness

[0044] A 0.2 mm thick film was prepared and cured for 7 days at 25°C / 50% (temperature 25°C, humidity 50%). The test was performed using a TADMA device.

[0045] 3. Shear strength

[0046] 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.

[0047] The test results are shown in Table 1.

[0048] Table 1 Performance test results of embodiments and comparative examples

[0049] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 hardness 45A 38A 33A 30A 27A 22A 82A Modulus / MPa 5.9 4.7 4 3.7 3.3 2.8 38 Shear strength / MPa 1.9 1.5 1.2 1.2 1 0.78 7

[0050] It can be seen from Table 1 that the present invention obtains a one-component reactive polyurethane hot melt adhesive with low modulus, low hardness and high shear strength by regulating the addition ratio of each component and the specific material type. Specifically, by selecting and adding low-crystallinity, soft crystalline polyester polyol, and adjusting the isocyanate index (R value) within the range of 1.2-1.6, the obtained one-component reactive polyurethane hot melt adhesive has low modulus and hardness, and the shear strength also meets the use requirements.

[0051] 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 modulus and low hardness one-component reactive polyurethane hot melt adhesive, characterized in that: The invention comprises the following components by weight: 15-40 parts of crystalline polyester polyol, 20-40 parts of liquid polyester polyol, 30-60 parts of polyether polyol, 0-1 part of monofunctional castor oil-based polyol, 0-10 parts of petroleum resin, 0-10 parts of EVA resin, 5-15 parts of diisocyanate, 0-1 part of auxiliary agent, 0.1-1 part of catalyst and 0-1 part of coupling agent.

2. The low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The crystalline polyester polyol is selected from any one or more of DYNACOLL 7362, DYNACOLL 7390, PRIPLAST 3162, PRIPLAST 3172, and PRIPLAST 3192.

3. The low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The isocyanate index is 1.2-1.

6.

4. The low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The liquid polyester polyol is selected from any one or more of DYNACOLL 7250, DYNACOLL 7255, and FLP2000PN.

5. The low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The polyether polyol is selected from any one or more of PPG2000, PPG4000, PPG6000, PPG8000, PO3G2000, and PTMG2000.

6. The low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The diisocyanate is selected from MDI or liquid MDI, and the coupling agent is selected from KH550, KH560 or KH590.

7. The low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The auxiliary agent is antioxidant 1010.

8. The low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 1, characterized in that: The petroleum resin is Eastman resin F100.

9. A method for preparing the low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: Crystalline polyester polyol, liquid polyester polyol, polyether polyol, petroleum resin, EVA resin and additives are stirred evenly in a reaction bottle, and vacuumed and dehydrated at high temperature; then the temperature is lowered to a certain temperature, diisocyanate is added, the temperature is raised to continue the reaction for a period of time, the vacuum is broken by nitrogen, monofunctional castor oil-based polyol, catalyst and coupling agent are added, stirring is continued for a period of time, the vacuum is broken by nitrogen, and the material is discharged to obtain the one-component reactive polyurethane hot melt adhesive.

10. The method for preparing the low modulus and low hardness one-component reactive polyurethane hot melt adhesive according to claim 9, characterized in that: The specific steps are: 15-40 parts of crystalline polyester polyol, 20-40 parts of liquid polyester polyol, 30-60 parts of polyether polyol, 0-10 parts of petroleum resin, 0-10 parts of EVA resin and 0-1 part of auxiliary agent are stirred evenly in a reaction bottle, and vacuum-dehydrated at 110-140° C. for 2-4 hours; then the temperature is lowered to 70-90° C., 5-15 parts of diisocyanate are added, the temperature is raised to 90-120° C., and the reaction is continued for 60-120 minutes, the vacuum is broken by nitrogen, 0-1 part of monofunctional castor oil-based polyol, 0.1-1 part of catalyst and 0-1 part of coupling agent are added, and the stirring is continued for 30-120 minutes, the vacuum is broken by nitrogen, and the material is discharged to obtain the one-component reactive polyurethane hot melt adhesive.