An outdoor special strong peel strength pressure-sensitive adhesive and its preparation method

Abstract

This application relates to the field of adhesives, and specifically discloses a special outdoor pressure-sensitive adhesive with strong peel strength and its preparation method. The pressure-sensitive adhesive is composed of the following substances in weight percentages: 55-65% of difunctional polyurethane acrylate resin, 1-5% of trifunctional polyurethane acrylate resin, 0.1-10% of hexafunctional polyurethane acrylate resin, 12.3-42.28% of diluent monomer, 1-6% of liquid free radical type I photoinitiator, 0.1-0.5% of antioxidant, 0.5-1% of ultraviolet absorber, and 0.02-0.2% of auxiliary agent. This application uses three different functional group polyurethane acrylates, combined with a liquid free radical type I photoinitiator and an active diluent monomer. The system has a low viscosity, a moderate initiation rate, and a moderate crosslinking density of the pressure-sensitive adhesive, achieving a balance between cohesive force and adhesive force, enabling the pressure-sensitive adhesive to simultaneously possess excellent peel strength and weather resistance, and leaving no residual glue on the surface of the adherend after peeling. It meets the requirements for outdoor use.

Description

Technical Field

[0001] The present application relates to the technical field of adhesives, and more specifically, it relates to a strong peel force pressure-sensitive adhesive for outdoor use and a preparation method thereof. Background Art

[0002] Pressure-sensitive adhesives are a special type of adhesives. Their inherent viscosity enables them to quickly wet and adhere to various different substrates under a small pressure. At the same time, when the bonding surface is damaged, the adhesive layer cannot remain on the surface of the bonded object. Due to their unique properties, pressure-sensitive adhesive products are widely used in various industries.

[0003] Currently, the solvent-based pressure-sensitive adhesives are widely used in the market. The construction conditions of the solvent-based pressure-sensitive adhesives are simple, but the proportion of organic solvents in the solvent-based pressure-sensitive adhesives is high, and the VOC volatilization amount is large during the construction process, which seriously endangers human health and violates the concept of national green and healthy development. In this field, the UV-curable pressure-sensitive adhesives are gradually used to replace the solvent-based pressure-sensitive adhesives. The main components of the photocurable pressure-sensitive adhesives include photosensitive resins, diluent monomers, photoinitiators, tackifying resins, additives, etc. Due to the influence of the curing system, the photocurable pressure-sensitive adhesives have a fast curing speed, and the curing reaction between the photosensitive resin and the diluent monomer is incomplete, and the peel force of the photocurable pressure-sensitive adhesives is low, and it is difficult to reach more than one kilogram. Summary of the Invention

[0004] In order to solve the problem of low peel force of the photocurable pressure-sensitive adhesives, the present application provides a strong peel force pressure-sensitive adhesive for outdoor use and a preparation method thereof.

[0005] In the first aspect, the present application provides a strong peel force pressure-sensitive adhesive for outdoor use, adopting the following technical scheme:

[0006] A strong peel force pressure-sensitive adhesive for outdoor use is composed of the following weight percentages:

[0007] Bifunctional polyurethane acrylate resin: 55 - 65%

[0008] Trifunctional polyurethane acrylate resin: 1 - 5%

[0009] Hexafunctional polyurethane acrylate resin: 0.1 - 10%

[0010] Diluent monomer: 12.3 - 42.28%

[0011] Liquid free radical type I photoinitiator: 1 - 6%

[0012] Antioxidant: 0.1 - 0.5%

[0013] Ultraviolet absorber: 0.5 - 1%

[0014] Additive: 0.02 - 0.2%.

[0015] Further, the viscosity of the difunctional polyurethane acrylate resin is 5000 to 7000 mPa·s.

[0016] Furthermore, the acid value of the difunctional polyurethane acrylate resin is 2 to 6 mgKOH / g.

[0017] Further, the viscosity of the trifunctional polyurethane acrylate resin is 5000 to 7000 mPa·s.

[0018] Further, the viscosity of the hexafunctional polyurethane acrylate resin is 15000 mPa·s.

[0019] Further, the liquid radical type I photoinitiator includes one or more of benzophenone acid modifiers, 2-hydroxy-2-methyl-1-phenyl-1-propanone, acetophenone acid modifiers, ethyl 2,4,6-trimethylbenzoylphosphinate, and mixtures of benzoylformate esters.

[0020] Further, the glass transition temperature of the diluent monomer is ≥103°C.

[0021] Further, the diluent monomer is at least three of methyl methacrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, methacrylamide, and glycidyl methacrylate.

[0022] Further, the antioxidant is a hindered phenol antioxidant and / or a co-antioxidant.

[0023] Furthermore, the hindered phenol antioxidants include but are not limited to 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexamethylenediamine.

[0024] Furthermore, the co-antioxidant is a phosphite antioxidant.

[0025] Further, the ultraviolet absorber is any one or more of salicylate ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers, and triazine ultraviolet absorbers.

[0026] Further, the ultraviolet absorber is at least one of 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2,2'-methylenebis(4-tert-octyl-6-benzotriazolylphenol), 2-hydroxy-4-n-octyloxybenzophenone, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-phenylpropionate octyl ester, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, hydroxy triazine derivative, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, and UV1130.

[0027] Further, the additives include a leveling agent and an antifoaming agent. The weight percentage of the leveling agent is 0.01-0.1%, and the weight percentage of the antifoaming agent is 0.01-0.1%.

[0028] Further, the leveling agent is a silicone leveling agent.

[0029] Further, the leveling agent is any one or more of BYK333, BYK306, BYK307, and BYK346.

[0030] Further, the antifoaming agent is one or more of BYK1790, BYK1798, and BYK1794.

[0031] In a second aspect, the present application provides a preparation method for an outdoor special strong peel force pressure-sensitive adhesive, adopting the following technical solution:

[0032] A preparation method for an outdoor special strong peel force pressure-sensitive adhesive includes the following steps:

[0033] Prepare according to weight percentages: difunctional polyurethane acrylate resin, trifunctional polyurethane acrylate resin, hexafunctional polyurethane acrylate resin, diluting monomer, liquid radical type I photoinitiator, antioxidant, ultraviolet absorber, and additives;

[0034] Blend the above raw materials to obtain an outdoor special strong peel force pressure-sensitive adhesive.

[0035] By adopting the above technical solution, the present application has at least the following advantages:

[0036] First, the present application combines difunctional, trifunctional, and hexafunctional polyurethane acrylate resins, and cooperates with diluting monomers, liquid radical type I photoinitiators, antioxidants, ultraviolet absorbers, and other additives to obtain a photocurable pressure-sensitive adhesive with high weather resistance, strong peel force, and no residual glue;

[0037] The reasons are as follows: The difunctional polyurethane acrylate provides the adhesion required for the pressure-sensitive adhesive. The trifunctional polyurethane acrylate regulates the photocuring speed of the pressure-sensitive adhesive. The hexafunctional polyurethane acrylate provides the cohesion required for the pressure-sensitive adhesive. Adjust the contents of the three to an appropriate proportion range, and cooperate with the reactive diluent monomer. Under the action of the liquid free radical type I photoinitiator, the polyurethane acrylates with three different functionalities are fully polymerized. The liquid free radical type I photoinitiator can not only provide the solubility of each component in the system, but also reduce the viscosity of the system. At the same time, the liquid free radical type I photoinitiator has a wide spectral characteristic, can absorb long-wavelength ultraviolet light and part of visible light, its reaction speed is fast, and the reaction rate between the difunctional polyurethane acrylates is increased. The polyurethane acrylates with three different functionalities are crosslinked with each other, and the crosslinking density of the pressure-sensitive adhesive is moderate, and the balance between cohesion and adhesion is achieved, so that the pressure-sensitive adhesive can simultaneously have excellent peel strength and weather resistance, and there is no residual adhesive on the surface of the adherend after peeling. It meets the needs of outdoor use.

[0038] Second, in this application, two specific liquid free radical type I initiators are selected for compounding use; different types of liquid free radical type I initiators can absorb ultraviolet light in different bands, so as to quickly crack and generate free radicals, and the crosslinking density between the polyurethane acrylates is slightly increased. On the premise of ensuring that the pressure-sensitive adhesive does not leave residual adhesive, the peel strength and yellowing resistance of the pressure-sensitive adhesive are improved.

[0039] Third, in this application, a variety of acrylate reactive diluent monomers are selected, so that the glass transition temperature of the reactive diluent monomer is controlled within an appropriate range, promoting the moderate cohesive strength of the pressure-sensitive adhesive, and obtaining excellent weather resistance, and the peel strength and yellowing resistance of the pressure-sensitive adhesive are balanced. Detailed implementation mode

[0040] This application will be further described in combination with the following examples, comparative examples and test data.

[0041] Difunctional polyurethane acrylate: It is made by a conventional method and customized according to viscosity and acid value;

[0042] Brand: 1#, viscosity 5000 - 7000 mPa·s, acid value < 1 mgKOH / g;

[0043] Brand: 2#, viscosity 5000 - 7000 mPa·s, acid value < 2 mgKOH / g;

[0044] Brand: 3#, viscosity 5000 - 7000 mPa·s, acid value < 6 mgKOH / g;

[0045] Brand: 4#, viscosity 5000 - 7000 mPa·s, acid value < 25 mgKOH / g;

[0046] Trifunctional polyurethane acrylate:

[0047] Brand: RU-3370B, viscosity 5000 - 7000 mPa·s, acid value < 1 mgKOH / g;

[0048] Brand: RU-3172B, viscosity 5000 - 7000 mPa·s, acid value < 3 mgKOH / g;

[0049] Hexafunctional polyurethane acrylate:

[0050] Brand: RU-6127B, viscosity 15000 mPa·s, acid value < 1 mgKOH / g.

[0051] Example 1

[0052] A strong peel force pressure - sensitive adhesive for outdoor use, by weight percentage:

[0053] Difunctional polyurethane acrylate resin 60%; Trifunctional polyurethane acrylate resin 5%; Hexafunctional polyurethane acrylate resin 10%; Dilution monomer 17.3%; Liquid free - radical type I photoinitiator 6%; Antioxidant 0.5%; Ultraviolet absorber 1%; Leveling agent 0.1%; Defoaming agent 0.1%;

[0054] Among them, the difunctional polyurethane acrylate resin is brand 3#, viscosity 5000 - 7000 mPa·s, acid value < 6 mgKOH / g;

[0055] The trifunctional polyurethane acrylate resin is RU-3370B;

[0056] The hexafunctional polyurethane acrylate resin is RU-6127B;

[0057] The dilution monomer is compounded by methyl methacrylate, methacrylamide, and glycidyl methacrylate in a weight ratio of 1:1:1. Methyl methacrylate, methacrylamide, and glycidyl methacrylate are all of analytical purity, and the Tg is 103 °C;

[0058] The liquid free - radical type I photoinitiator is Lencolo 5024;

[0059] The antioxidant is 1,3,5 - tris(3,5 - di - tert - butyl - 4 - hydroxybenzyl) isocyanuric acid, sourced from Zhengzhou Alpha Chemical Co., Ltd.;

[0060] The ultraviolet absorber is UV1130;

[0061] The leveling agent is BYK307;

[0062] The defoamer is BYK1794.

[0063] Examples 2 - 3

[0064] A strong - peel - force pressure - sensitive adhesive for outdoor use, the difference from Example 1 lies in that: the weight percentages of each component are different, specifically as follows:

[0065] In Example 2, difunctional polyurethane acrylate resin is 55%; trifunctional polyurethane acrylate resin is 1%; hexafunctional polyurethane acrylate resin is 0.1%; diluent monomer is 42.28%; liquid free - radical type I photo - initiator is 1%; antioxidant is 0.1%; ultraviolet absorber is 0.5%; leveling agent is 0.01%; defoamer is 0.01%.

[0066] In Example 3, difunctional polyurethane acrylate resin is 65%; trifunctional polyurethane acrylate resin is 5%; hexafunctional polyurethane acrylate resin is 10%; diluent monomer is 12.3%; liquid free - radical type I photo - initiator is 6%; antioxidant is 0.5%; ultraviolet absorber is 1%; leveling agent is 0.1%; defoamer is 0.1%.

[0067] Examples 4 - 6

[0068] A strong - peel - force pressure - sensitive adhesive for outdoor use, the difference from Example 1 lies in that: the grades of difunctional polyurethane acrylate resin are different, specifically as follows:

[0069] In Example 4, difunctional polyurethane acrylate resin of grade 2# is used to replace difunctional polyurethane acrylate resin of grade 3# with equal weight percentage.

[0070] In Example 5, difunctional polyurethane acrylate resin of grade 4# is used to replace difunctional polyurethane acrylate resin of grade 3# with equal weight percentage.

[0071] In Example 6, difunctional polyurethane acrylate resin of grade 1# is used to replace difunctional polyurethane acrylate resin of grade 3# with equal weight percentage.

[0072] Example 7

[0073] A strong - peel - force pressure - sensitive adhesive for outdoor use, the difference from Example 1 lies in that: the grade of trifunctional polyurethane acrylate resin is different, and RU - 3172B is used to replace RU - 3370B with equal weight percentage.

[0074] Example 8

[0075] A strong - peel - force pressure - sensitive adhesive for outdoor use, the difference from Example 1 lies in that: the liquid free - radical type I photo - initiator is composed of 2 - hydroxy - 2 - methyl - 1 - phenyl - 1 - propanone and Lencolo 5024 in a weight ratio of 1:1.

[0076] Example 9

[0077] A pressure-sensitive adhesive with strong peel strength for outdoor use, which is different from that of Example 1 in that the diluting monomer is hydroxyethyl acrylate and the Tg is -15°C.

[0078] Example 10

[0079] A pressure-sensitive adhesive with strong peel strength for outdoor use, which is different from that of Example 1 in that the diluting monomer is methacrylic acid and the Tg is 185°C.

[0080] Comparative Example 1

[0081] A solvent-based pressure-sensitive adhesive, and its model is Ashland 951059.

[0082] Comparative Example 2

[0083] A pressure-sensitive adhesive, which is different from that of Example 1 in that a trifunctional polyurethane acrylate resin is used to replace the difunctional polyurethane acrylate resin in an equal weight percentage.

[0084] Comparative Example 3

[0085] A pressure-sensitive adhesive, which is different from that of Example 1 in that a trifunctional polyurethane acrylate resin is used to replace the hexafunctional polyurethane acrylate resin in an equal weight percentage.

[0086] Comparative Example 4

[0087] A pressure-sensitive adhesive, which is different from that of Example 1 in that a hexafunctional polyurethane acrylate resin is used to replace the trifunctional polyurethane acrylate resin in an equal weight percentage.

[0088] Test data

[0089] Using TPU as the substrate, the pressure-sensitive adhesives prepared in Examples 1-10 and Comparative Examples 1-4 are coated on the surface of the TPU substrate. The dry film thickness of the pressure-sensitive adhesive is 25 μm, and the peel strength is tested under the same test conditions.

[0090] Table 1. Test data of various performances of Examples 1-10

[0091]

[0092] Table 2. Test data of various performances of Example 1 and Comparative Examples 1-4

[0093]

[0094] It can be seen from the above test data that:

[0095] In each embodiment of this application, the peel strength is higher than 1 kg / in, indicating that the pressure-sensitive adhesive tape prepared in this application has a very high peel force. After the pressure-sensitive adhesive tape is irradiated by QUV for 1500 h, the peel strength of the pressure-sensitive adhesive tape increases, the yellowing index increases, but there is no residual glue. Thus, it can be seen that the pressure-sensitive adhesive tape has good weather resistance and can be used in outdoor application scenarios.

[0096] In order to further demonstrate the advantages of the technical solution of this application, a typical commercially available solvent-based pressure-sensitive adhesive was selected for comparison. Comparative Example 1 is a solvent-based polyurethane acrylate pressure-sensitive adhesive. The differences between Comparative Example 1 and Example 1 of this application are as follows: The peel force of Comparative Example 1 when sticking and tearing immediately is 1.36 kg / in. After aging for 1500 h in Comparative Example 1, the peel force increased to 2.78 kg / in, but residual glue appeared. It can be seen from this that the initial peel force and the peel force after aging detection of the UV-type pressure-sensitive adhesive prepared in this application are not much different from those of traditional solvent-based pressure-sensitive adhesives. It has excellent bonding performance, no trouble of residual glue, simple and environmentally friendly curing method, and has high development potential.

[0097] In addition, in order to explore the functions of three different functional group polyurethane acrylates, Example 1 was compared with Comparative Examples 2-4 alone. In Comparative Example 2, the difunctional group polyurethane acrylate was missing, and its peel force decreased significantly, dropping below 1 kg / in; in Comparative Example 3, the hexafunctional group polyurethane acrylate was missing, and its cohesive strength decreased significantly, and residual glue appeared after aging treatment, and the yellowing index increased; in Comparative Example 4, the trifunctional group polyurethane acrylate resin was missing, and the cohesive strength of the pressure-sensitive adhesive was too high, and the peel force decreased.

[0098] Example 1 was compared with Examples 2-3 alone. The difference is that the component weight percentages of Examples 1-3 are different. According to the experimental data, under the weight percentage recorded in Example 1, the pressure-sensitive adhesive system can have both excellent peel force and weather resistance.

[0099] Example 1 was compared with Examples 4-6 alone. The difference is that the acid values of the difunctional group polyurethane acrylate and trifunctional group polyurethane acrylate in the pressure-sensitive adhesive are different. According to the experimental data, when the acid values of the di / trifunctional group polyurethane acrylate increase, although it helps to improve the peel force of the pressure-sensitive adhesive, after aging treatment, its yellowing resistance performance is not good, the yellowing index increases, and obvious discoloration will occur.

[0100] Example 1 was compared with Example 8 alone. The difference is only that in Example 8, a compound liquid radical type I photoinitiator is used. The main absorption light bands of the above two liquid radical type I photoinitiators are different, and they can absorb a relatively wide ultraviolet light band to generate free radicals, so that the pressure-sensitive adhesive system is cured sufficiently, the cohesive strength and the adhesion force are balanced, the peel force increases, and after aging treatment, the yellowing index slightly increases and no residual glue remains.

[0101] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0102] Moreover, the above-described embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it cannot be understood as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A strong peeling force pressure-sensitive adhesive for outdoor use, characterized in that: The composition is as follows by weight percentage: Difunctional polyurethane acrylic resin 55~65% Trifunctional polyurethane acrylic resin 1~5% Hexafunctional polyurethane acrylic resin 0.1~10% Diluted monomer 12.3~42.28% Liquid free radical type I photoinitiator 1~6% Antioxidant 0.1~0.5% UV absorber 0.5~1% Additives 0.02~0.2%.

2. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 1, characterized in that: The viscosity of the difunctional polyurethane acrylic resin is 5000-7000 mPa·s.

3. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 2, characterized in that: The acid value of the difunctional polyurethane acrylic resin is 2-6 mgKOH / g.

4. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 1, characterized in that: The viscosity of the trifunctional polyurethane acrylic resin is 5000-7000 mPa·s.

5. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 4, characterized in that: The viscosity of the hexafunctional polyurethane acrylic resin is 15000 mPa·s.

6. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 1, characterized in that: The liquid free radical type I photoinitiator includes one or more of modified benzoic acid, 2-hydroxy-2-methyl-1-phenyl-1-propanone, modified phenylacetoacetic acid, ethyl 2,4,6-trimethylbenzoylphosphonate, and a mixture of benzoyl formate.

7. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 1, characterized in that: The glass transition temperature of the diluent monomer is ≥103°C.

8. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 1, characterized in that: The diluent monomers are at least three of methyl methacrylate, tetrahydrofuran acrylate, isobornyl acrylate, methacrylamide, and glycidyl methacrylate.

9. The outdoor-specific strong peeling pressure-sensitive adhesive according to claim 8, characterized in that: The auxiliary agent comprises a leveling agent and a defoaming agent, the weight percentage of the leveling agent is 0.01-0.1%, and the weight percentage of the defoaming agent is 0.01-0.1%.

10. The method for preparing a high-peeling pressure-sensitive adhesive for outdoor use according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: preparing, according to weight percentage, difunctional polyurethane acrylic resin, trifunctional polyurethane acrylic resin, hexafunctional polyurethane acrylic resin, diluent monomer, liquid free radical type I photoinitiator, antioxidant, ultraviolet absorber and auxiliary agent; blending the above raw materials to obtain a special outdoor strong peeling force pressure-sensitive adhesive.

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