Outdoor special pressure-sensitive adhesive with strong stripping force and preparation method of outdoor special pressure-sensitive adhesive

Abstract

The invention relates to the field of adhesives, and particularly discloses a special outdoor high-stripping-force pressure-sensitive adhesive and a preparation method thereof. The pressure-sensitive adhesive is prepared from the following substances in percentage by weight: 55 to 65 percent of two-functional group polyurethane acrylic resin, 1 to 5 percent of three-functional group polyurethane acrylic resin, 0.1 to 10 percent of six-functional group polyurethane acrylic resin, 12.3 to 42.28 percent of diluting monomer, 1 to 6 percent of liquid free radical I type photoinitiator, 0.1 to 0.5 percent of antioxidant, 0.5 to 1 percent of ultraviolet absorbent and 0.02 to 0.2 percent of additive. According to the pressure-sensitive adhesive disclosed by the invention, three different functional group polyurethane acrylates are adopted and are matched with the liquid free radical I type photoinitiator and the active diluting monomer, so that the system viscosity is low, the initiation rate is moderate, the crosslinking density of the pressure-sensitive adhesive is moderate, and cohesion and adhesive strength are balanced, so that the pressure-sensitive adhesive has excellent stripping force and weather resistance at the same time, and the service life of the pressure-sensitive adhesive is prolonged. And no residual adhesive is left on the surface of the adhered object after stripping. And the outdoor use requirement is met.

Description

Technical Field

[0001] The present application relates to the technical field of adhesives, and more specifically, to a high-peeling pressure-sensitive adhesive specially designed for outdoor use and a preparation method thereof. Background Art

[0002] Pressure sensitive adhesives are a special type of adhesives. Their inherent stickiness allows them to quickly wet and adhere to a variety of different substrates under slight pressure. At the same time, when the bonding surface is damaged, the adhesive layer cannot remain on the surface of the adherend. Due to its unique properties, pressure sensitive adhesive products are widely used in various industries.

[0003] At present, the pressure-sensitive adhesives widely used in the market are solvent-based pressure-sensitive adhesives. The construction conditions of solvent-based pressure-sensitive adhesives are simple, but the proportion of organic solvents in solvent-based pressure-sensitive adhesives is high, and the amount of VOC volatilization during the construction process is large, which seriously endangers human health and violates the country's concept of green and healthy development. In this field, UV-curable pressure-sensitive adhesives are gradually used to replace solvent-based pressure-sensitive adhesives. The main components of 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 adhesive has a fast curing speed, the curing reaction between the photosensitive resin and the diluent monomer is incomplete, and the peeling force of the photocurable pressure-sensitive adhesive is low, and it is difficult to reach above the kilogram level. Summary of the invention

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

[0005] In the first aspect, the present application provides a strong peeling force pressure-sensitive adhesive for outdoor use, which adopts the following technical solution: A strong peeling force pressure-sensitive adhesive specially used for outdoor use, composed according to the following weight percentages: 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%.

[0006] Furthermore, the viscosity of the difunctional polyurethane acrylic resin is 5000-7000 mPa·s.

[0007] Furthermore, the acid value of the difunctional polyurethane acrylic resin is 2 to 6 mgKOH / g.

[0008] Furthermore, the viscosity of the trifunctional polyurethane acrylic resin is 5000-7000 mPa·s.

[0009] Furthermore, the viscosity of the hexafunctional polyurethane acrylic resin is 15000 mPa·s.

[0010] Furthermore, the liquid free radical type I photoinitiator includes one or more of modified benzoic acid, 2-hydroxy-2-methyl-1-phenyl-1-propanone, modified phenylacetoic acid, ethyl 2,4,6-trimethylbenzoylphosphonate, and a mixture of benzoyl formate.

[0011] Furthermore, the glass transition temperature of the diluent monomer is ≥103°C.

[0012] Furthermore, the diluent monomers are at least three of methyl methacrylate, tetrahydrofuran acrylate, isobornyl acrylate, methacrylamide, and glycidyl methacrylate.

[0013] Furthermore, the antioxidant is a hindered phenol antioxidant and / or an auxiliary antioxidant.

[0014] Furthermore, the hindered phenol antioxidant includes but is not limited to 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl, 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.

[0015] Furthermore, the auxiliary antioxidant is a phosphite antioxidant.

[0016] Furthermore, the ultraviolet absorber is any one or more of a salicylate ultraviolet absorber, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a substituted acrylonitrile ultraviolet absorber and a triazine ultraviolet absorber.

[0017] Furthermore, the ultraviolet absorber is 2-(2H-benzotriazole-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-benzotriazolephenol), 2-hydroxy-4-n-octyloxybenzophenone, 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, )-6-dodecyl-4-methylphenol, 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-phenylpropionic acid octyl ester, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, hydroxytriazine derivatives, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole and at least one of UV1130.

[0018] Furthermore, the auxiliary agent includes 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%.

[0019] Furthermore, the leveling agent is an organic silicon leveling agent.

[0020] Furthermore, the leveling agent is any one or more of BYK333, BYK306, BYK307 and BYK346.

[0021] Furthermore, the defoaming agent is one or more of BYK1790, BYK1798 and BYK1794.

[0022] In the second aspect, the present application provides a method for preparing a high-peeling pressure-sensitive adhesive for outdoor use, which adopts the following technical solution: A method for preparing a high-peeling pressure-sensitive adhesive for outdoor use, comprising the following steps: Prepare 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; The above raw materials are blended to obtain a strong peeling force pressure-sensitive adhesive specially used for outdoor use.

[0023] By adopting the above technical solution, this application has at least the following advantages: First, the present application obtains a light-curable pressure-sensitive adhesive with high weather resistance, strong peeling force and no residual adhesive by compounding difunctional, trifunctional and hexafunctional polyurethane acrylic resins with diluent monomers, liquid free radical type I photoinitiator, antioxidant, ultraviolet absorber and other additives; The reasons are as follows: difunctional polyurethane acrylate provides the required adhesion of pressure-sensitive adhesive, trifunctional polyurethane acrylate adjusts the light curing speed of pressure-sensitive adhesive, and hexafunctional polyurethane acrylate provides the required cohesive force of pressure-sensitive adhesive; the contents of the three are adjusted to a suitable ratio, and the three polyurethane acrylates with different functionalities are fully polymerized under the action of liquid free radical type I photoinitiator in combination with active diluent monomers; 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, liquid free radical type I photoinitiator has a wide spectrum characteristic, can absorb long-wave ultraviolet light and part of visible light, and has a fast reaction speed, and the reaction rate between difunctional polyurethane acrylates is increased; three polyurethane acrylates with different functionalities are cross-linked with each other, the cross-linking density of the pressure-sensitive adhesive is moderate, and the cohesive force and adhesive force are balanced, so that the pressure-sensitive adhesive can have excellent peeling force and weather resistance at the same time, and there is no residual glue on the surface of the adhered object after peeling. Meet the needs of outdoor use.

[0024] Second, two specific liquid free radical type I initiators are selected for compound use in this application; different types of liquid free radical type I initiators can absorb ultraviolet light of different bands, so that they can quickly decompose to produce free radicals, and the cross-linking density between polyurethane acrylates is slightly increased. Under the premise of ensuring that the pressure-sensitive adhesive does not leave residual adhesive, the peeling force and yellowing resistance of the pressure-sensitive adhesive are improved.

[0025] Third, a variety of acrylic acid ester active diluent monomers are selected in the present application, so that the glass transition temperature of the active diluent monomers is controlled within a suitable range, so that the cohesive strength of the pressure-sensitive adhesive is moderate, and excellent weather resistance is obtained, and the peeling force and yellowing resistance of the pressure-sensitive adhesive are balanced. DETAILED DESCRIPTION

[0026] The present application is further described in conjunction with the following examples, comparative examples and test data.

[0027] Difunctional polyurethane acrylate: Made by conventional methods, customized according to viscosity and acid value; Brand: 1#, viscosity 5000~7000mPa·s, acid value <1mgKOH / g; Brand: 2#, viscosity 5000~7000mPa·s, acid value <2mgKOH / g; Brand: 3#, viscosity 5000~7000mPa·s, acid value <6mgKOH / g; Brand: 4#, viscosity 5000~7000mPa·s, acid value <25mgKOH / g; Trifunctional polyurethane acrylate: Brand: RU-3370B, viscosity 5000~7000mPa·s, acid value <1mgKOH / g; Brand: RU-3172B, viscosity 5000~7000mPa·s, acid value <3mgKOH / g; Hexafunctional polyurethane acrylate: Brand: RU-6127B, viscosity 15000mPa·s, acid value <1mgKOH / g.

[0028] Example 1

[0029] A strong peeling force pressure-sensitive adhesive specially used for outdoor use, calculated by weight percentage: Difunctional polyurethane acrylic resin 60%; trifunctional polyurethane acrylic resin 5%; hexafunctional polyurethane acrylic resin 10%; diluent monomer 17.3%; liquid free radical type I photoinitiator 6%; antioxidant 0.5%; ultraviolet absorber 1%; leveling agent 0.1%; defoaming agent 0.1%; Wherein, the difunctional polyurethane acrylic resin is grade 3#, with a viscosity of 5000-7000 mPa·s and an acid value of <6 mgKOH / g; The trifunctional polyurethane acrylic resin is RU-3370B; The hexafunctional polyurethane acrylic resin is RU-6127B; The diluent monomer is prepared by compounding methyl methacrylate, methacrylamide and glycidyl methacrylate in a weight ratio of 1:1:1. Methyl methacrylate, methacrylamide and glycidyl methacrylate are all analytically pure and have a Tg of 103°C. The liquid free radical type I photoinitiator was Lencolo 5024; The antioxidant was 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid, which was sourced from Zhengzhou Alpha Chemical Co., Ltd.; The ultraviolet absorber is UV1130; The leveling agent is BYK307; The defoaming agent is BYK1794.

[0030] Example 2-3 A special outdoor strong peeling pressure-sensitive adhesive, which is different from Example 1 in that the weight percentages of the various components are different, as follows: In Example 2, difunctional polyurethane acrylic resin 55%; trifunctional polyurethane acrylic resin 1%; hexafunctional polyurethane acrylic resin 0.1%; diluent monomer 42.28%; liquid free radical type I photoinitiator 1%; antioxidant 0.1%; ultraviolet absorber 0.5%; leveling agent 0.01%; defoaming agent 0.01%; In Example 3, the difunctional polyurethane acrylic resin is 65%; the trifunctional polyurethane acrylic resin is 5%; the hexafunctional polyurethane acrylic resin is 10%; the diluent monomer is 12.3%; the liquid free radical type I photoinitiator is 6%; the antioxidant is 0.5%; the ultraviolet absorber is 1%; the leveling agent is 0.1%; and the defoaming agent is 0.1%.

[0031] Embodiment 4-6 A special outdoor strong peeling pressure-sensitive adhesive, which is different from Example 1 in that the brand of the difunctional polyurethane acrylic resin is different, as follows: In Example 4, the difunctional polyurethane acrylic resin of brand 2# is used in equal weight percentage to replace the difunctional polyurethane acrylic resin of brand 3#; In Example 5, the difunctional polyurethane acrylic resin of brand 4# is used in equal weight percentage to replace the difunctional polyurethane acrylic resin of brand 3#; In Example 6, the difunctional polyurethane acrylic resin of brand No. 1 is used in an equal weight percentage to replace the difunctional polyurethane acrylic resin of brand No. 3.

[0032] Example 7

[0033] A pressure-sensitive adhesive with strong peeling force specially used for outdoor use, which is different from Example 1 in that the brand of trifunctional polyurethane acrylic resin is different, and RU-3172B is used instead of RU-3370B in an equal weight percentage.

[0034] Example 8

[0035] A pressure-sensitive adhesive with strong peeling force specially used for outdoor use, which differs from Example 1 in that: a liquid free radical type I photoinitiator is compounded by 2-hydroxy-2-methyl-1-phenyl-1-propanone and Lencolo 5024 in a weight ratio of 1:1.

[0036] Example 9

[0037] A high-peeling-force pressure-sensitive adhesive for outdoor use, which differs from Example 1 in that the diluent monomer is hydroxyethyl acrylate and has a Tg of -15°C.

[0038] Example 10

[0039] A high-peeling-force pressure-sensitive adhesive specially used for outdoor use, which is different from Example 1 in that the diluent monomer is methacrylic acid and the Tg is 185°C.

[0040] Comparative Example 1 A solvent-based pressure-sensitive adhesive, model number is Ashland 951059.

[0041] Comparative Example 2 A pressure-sensitive adhesive, which is different from Example 1 in that an equal weight percentage of trifunctional polyurethane acrylic resin is used instead of difunctional polyurethane acrylic resin.

[0042] Comparative Example 3 A pressure-sensitive adhesive, which is different from Example 1 in that an equal weight percentage of trifunctional polyurethane acrylic resin is used instead of hexafunctional polyurethane acrylic resin.

[0043] Comparative Example 4 A pressure-sensitive adhesive, which is different from Example 1 in that an equal weight percentage of hexafunctional polyurethane acrylic resin is used instead of trifunctional polyurethane acrylic resin.

[0044] Test data Using TPU as the substrate, the pressure-sensitive adhesive prepared in Examples 1-10 and Comparative Examples 1-4 was coated on the surface of the TPU substrate, the dry film thickness of the pressure-sensitive adhesive was 25 μm, and the peeling force was tested under the same test conditions.

[0045] Table 1. Performance test data of Examples 1-10

[0046] Table 2. Performance test data of Example 1 and Comparative Examples 1-4

[0047] According to the above test data, it can be seen that: The peel strength of each embodiment in this application is higher than 1kg / in, indicating that the pressure-sensitive tape prepared in this application has a very high peel force. After the pressure-sensitive tape is irradiated with QUV for 1500 hours, the peel strength of the pressure-sensitive tape increases, the yellowing index increases, but there is no residual adhesive, which shows that the pressure-sensitive tape has good weather resistance and can be used in outdoor applications.

[0048] In order to further demonstrate the advantages of the technical solution of the present application, a typical commercially available solvent-based pressure-sensitive adhesive is 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 the present application are as follows: the peeling force of Comparative Example 1 is 1.36kg / in, and after aging for 1500h, the peeling force of Comparative Example 1 increases to 2.78kg / in, but residual glue appears; it can be seen that the initial peeling force and the peeling force after aging test of the UV-type pressure-sensitive adhesive prepared by the present application are not much different from those of the traditional solvent-based pressure-sensitive adhesive, with excellent bonding performance, no residual glue problem, simple and environmentally friendly curing method, and high development potential.

[0049] In addition, in order to explore the effects of three different functional polyurethane acrylates, Example 1 and Comparative Examples 2-4 form a single comparison. Comparative Example 2 lacks difunctional polyurethane acrylate, and its peel force is significantly reduced to below 1kg / in; Comparative Example 3 lacks hexafunctional polyurethane acrylate, and its cohesive strength is significantly reduced. Residual glue appears after aging treatment, and the yellowing index increases; Comparative Example 4 lacks trifunctional polyurethane acrylic resin, the cohesive strength of the pressure-sensitive adhesive is too high, and the peel force is reduced.

[0050] Example 1 forms a single comparison with Examples 2-3, the difference being that the weight percentages of the components in Examples 1-3 are different. Experimental data show that at the weight percentage recorded in Example 1, the pressure-sensitive adhesive system can have both excellent peeling force and weather resistance.

[0051] Example 1 and Examples 4-6 form a single comparison. The difference lies in that the acid values ​​of the difunctional polyurethane acrylate and the trifunctional polyurethane acrylate in the pressure-sensitive adhesive are different. According to the experimental data, although the increase in the acid value of the di / trifunctional polyurethane acrylate helps to improve the peeling force of the pressure-sensitive adhesive, after aging treatment, its yellowing resistance is poor, the yellowing index increases, and obvious discoloration will occur.

[0052] Example 1 forms a single contrast with Example 8, and the only difference is that a composite liquid free radical type I photoinitiator is used in Example 8. The two liquid free radical type I photoinitiators have different main absorption light bands and can absorb a wider ultraviolet light band to generate free radicals, so that the pressure-sensitive adhesive system is fully cured, the cohesive strength and the bonding force are balanced, the peel force is increased, and after aging resistance treatment, the yellowing index is slightly increased, and no residual glue is left.

[0053] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] Moreover, the above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached 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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