Preparation method of UV-aging-resistant polyurethane pressure-sensitive adhesive protective film

Abstract

The invention discloses a preparation method of a UV-aging-resistant polyurethane pressure-sensitive adhesive protective film, and belongs to the technical field of pressure-sensitive adhesives. The preparation method comprises the following steps: (1) adding an organic solvent into a polyurethane adhesive, and uniformly mixing to obtain a solution 1; (2) adding an indium tin oxide dispersion liquid into the solution 1, and uniformly mixing to obtain a suspension 1; (3) adding trifluoropropyl polyhedral oligomeric silsesquioxane into the suspension 1, and uniformly mixing to obtain a suspension 2; (4) adding a curing agent into the suspension 2, and uniformly mixing to obtain a pressure-sensitive adhesive mixed solution; and (5) blade-coating a film with the pressure-sensitive adhesive mixed solution obtained in the step (4), drying, laminating, rolling, and curing to obtain the pressure-sensitive adhesive. The polyurethane pressure-sensitive adhesive protective film prepared by the invention has good ultraviolet shielding performance, and the stability of a polyurethane adhesive layer is improved through cooperation of indium tin oxide and modified POSS (Polyhedral Oligomeric Silsesquioxane).

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of pressure-sensitive adhesive, in particular to a preparation method of a UV-aging-resistant polyurethane pressure-sensitive adhesive protective film. BACKGROUND

[0002] With the improvement of the requirements of electronic products on environmental protection, use environment and biological safety, higher requirements are put forward for the process protective film and the delivery protective film. In the industry, the use material of the protective film is gradually changed from polyacrylate to polyurethane protective film which has better stability and biological safety, but the polyurethane molecular chain contains many unsaturated bonds, and the irradiation of ultraviolet light will cause the degradation of the polyurethane molecular chain, reduce the mechanical properties of the polyurethane adhesive layer, cause cohesive failure of the adhesive layer, and greatly affect the use stability of the product. In view of the above industry problems, a polyurethane protective film resistant to ultraviolet light is needed to fill the market gap. SUMMARY

[0003] In order to solve the above-mentioned deficiencies existing in the prior art, the purpose of the present application is to provide a preparation method of a UV-aging-resistant polyurethane pressure-sensitive adhesive protective film, so as to improve the shielding ability and stability of the polyurethane pressure-sensitive adhesive protective film to ultraviolet light.

[0004] The technical scheme for solving the above-mentioned technical problems is as follows: a preparation method of a UV-aging-resistant polyurethane pressure-sensitive adhesive protective film is provided, comprising the following steps: (1) adding an organic solvent to a polyurethane adhesive, and mixing to obtain solution 1; (2) adding an indium tin oxide dispersion liquid to the solution 1, and mixing to obtain suspension 1; (3) adding trifluoropropyl cage silsesquioxane to the suspension 1, and mixing to obtain suspension 2; (4) adding a curing agent to the suspension 2, and mixing to obtain a pressure-sensitive adhesive mixed liquid; (5) coating the pressure-sensitive adhesive mixed liquid of step (4) on a film, drying to form a film, and then rolling, and then aging to obtain.

[0005] Further, the molecular weight of the polyurethane adhesive is 25000-40000 g / mol, the isocyanate hard segment content is 20%-40%, the hard segment in the main chain is an isocyanate containing a benzene ring, and the soft segment is a polyether polyol.

[0006] Further, the organic solvent is at least one of acetone, butanone, methyl acetate, ethyl acetate, n-butyl acetate, toluene and xylene.

[0007] Further, the indium tin ratio of the indium tin oxide dispersion liquid is 95-80:5-20.

[0008] Further, the curing agent is an aliphatic polyisocyanate curing agent.

[0009] Further, the aliphatic polyisocyanate curing agent includes at least one of hydrogenated xylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hexamethyl diisocyanate.

[0010] Further, the film is PET, PO, PI, or PP.

[0011] Further, the temperature of the maturation is 40-60°C, and the time is 1-3 days.

[0012] Further, the mass ratio of the polyurethane adhesive, the organic solvent, the indium tin oxide, the trifluoropropyl cage-type silsesquioxane, and the curing agent is 100:20-50:0.5-10:1-5:0.5-3.

[0013] The present application has the following beneficial effects: (1) The present application uses POSS as a kind of macromolecular additive, and the refractive index is 1.4-1.5, while the refractive index of polyurethane is about 1.45, so adding POSS in polyurethane will not affect the optical consistency of the adhesive layer.

[0014] (2) The silicon atom in the trifluoropropyl cage-type silsesquioxane (trifluoropropyl-POSS) in the present application gives it good ultraviolet light shielding ability at 150-300 nm, and reaches peak absorption at about 195 nm; the fluorine atom can absorb the free radicals generated by polyurethane under ultraviolet light, avoiding further damage to the molecular chain structure of polyurethane, and enhancing the weather resistance of the adhesive layer; at the same time, it can absorb ultraviolet light in the 200-300 nm band and dissipate heat, further enhancing the absorption and shielding ability of UVB.

[0015] (3) The present application uses indium tin oxide as a conductive agent to reduce the surface resistance of the adhesive layer and avoid the influence of electrostatic breakdown on product performance. At the same time, indium oxide, as the main component of indium tin oxide, has a refractive index of 1.52-1.54, good optical consistency with the polyurethane adhesive layer, and almost no absorption of visible light in the range of 400-800 nm. When the tin content of indium tin oxide is less than 20%, it can have good ultraviolet shielding performance and high visible light transmittance at the same time. The range of ultraviolet light absorbed by indium tin oxide is 300-400 nm, and the peak absorption range is 330-350 nm, which has good absorption and shielding ability for UVA.

[0016] (4) The present application absorbs ultraviolet light in the range of 200-400 nm through the cooperation of indium tin oxide and trifluoropropyl-POSS, and eliminates most free radicals through fluorine atoms, achieving the effect of increasing the stability of the polyurethane adhesive layer. DETAILED DESCRIPTION

[0017] The following examples are intended to illustrate the present application and are not intended to limit the scope of the application. Unless otherwise indicated, conventional conditions or manufacturer's recommended conditions were used in the examples. Unless otherwise indicated, the reagents or instruments used were conventional products available commercially.

[0018] Example 1: A method for preparing a UV aging resistant polyurethane pressure sensitive adhesive protective film, comprising the following steps: (1) Put trifluoropropyl cage polysiloxane (trifluoropropyl-POSS) into an 80°C oven and dry for 8h, take it out and put it into a drying dish to cool for 12h after drying, and prepare modified POSS; (2) Take 100g of polyurethane adhesive, add 50g of ethyl acetate and 50g of toluene, and use a high-speed mixer to stir at a speed of 3000 rad / min for 20min to obtain solution 1; (3) Add 7g of indium tin oxide (indium tin ratio 95:5) dispersion to solution 1, and use a high-speed mixer to stir at a speed of 1500 rad / min for 25min, and after sufficient stirring, obtain suspension 1; (4) Add 1g of modified POSS of step (1) to suspension 1, and use a high-speed mixer to stir at a speed of 1500 rad / min for 25min, and after sufficient stirring, obtain suspension 2; (5) Add 1.5g of isofluroketone diisocyanate curing agent to suspension 2, and use a high-speed mixer to stir at a speed of 2000 rad / min for 15min, and after sufficient stirring, obtain a pressure sensitive adhesive mixture; (6) Use a 10μm doctor blade to coat the pressure sensitive adhesive mixture on a 50μm PET film, and after drying in a 120°C oven for 1min, the film is wound and then placed in a 40°C oven for 3 days to prepare.

[0019] Example 2: A method for preparing a UV aging resistant polyurethane pressure sensitive adhesive protective film, comprising the following steps: (1) Put trifluoropropyl cage polysiloxane (trifluoropropyl-POSS) into an 80°C oven and dry for 8h, take it out and put it into a drying dish to cool for 12h after drying, and prepare modified POSS; (2) Take 100g of polyurethane adhesive, add 50g of ethyl acetate and 50g of toluene, and use a high-speed mixer to stir at a speed of 3000 rad / min for 20min to obtain solution 1; (3) 10 g of indium tin oxide (indium tin ratio 90:10) dispersion liquid was added to solution 1, and stirred at a speed of 1500 rad / min for 25 min using a high-speed mixer, and after sufficient stirring, suspension 1 was obtained; (4) 5 g of modified POSS of step (1) was added to suspension 1, and stirred at a speed of 1500 rad / min for 25 min using a high-speed mixer, and after sufficient stirring, suspension 2 was obtained; (5) 2 g of hydrogenated xylylene diisocyanate curing agent was added to suspension 2, and stirred at a speed of 2000 rad / min for 15 min using a high-speed mixer, and after sufficient stirring, a pressure-sensitive adhesive mixture was obtained; (6) The pressure-sensitive adhesive mixture was coated on a 50 μm PP film using a 10 μm doctor blade, dried in a 120°C oven for 1 min, and then wound after coating, and then placed in a 60°C oven for 1 day to cure, thereby being prepared.

[0020] Example 3: A method for preparing a UV aging resistant polyurethane pressure-sensitive adhesive protective film, comprising the following steps: (1) Trifluoropropyl cage silsesquioxane (trifluoropropyl-POSS) was placed in a 100°C oven and dried for 8 h, and after drying, it was taken out and placed in a drying dish and cooled for 12 h to prepare modified POSS; (2) 100 g of polyurethane adhesive was taken, 30 g of n-butyl acetate and 30 g of xylene were added, and stirred at a speed of 3000 rad / min for 20 min using a high-speed mixer to obtain solution 1; (3) 5 g of indium tin oxide (indium tin ratio 85:15) dispersion liquid was added to solution 1, and stirred at a speed of 1500 rad / min for 25 min using a high-speed mixer, and after sufficient stirring, suspension 1 was obtained; (4) 3 g of modified POSS of step (1) was added to suspension 1, and stirred at a speed of 1500 rad / min for 25 min using a high-speed mixer, and after sufficient stirring, suspension 2 was obtained; (5) 1.5 g of hexamethyl diisocyanate curing agent was added to suspension 2, and stirred at a speed of 2000 rad / min for 15 min using a high-speed mixer, and after sufficient stirring, a pressure-sensitive adhesive mixture was obtained; (6) The pressure-sensitive adhesive mixture was coated on a 50 μm PO film using a 10 μm doctor blade, dried in a 120°C oven for 1 min, and then wound after coating, and then placed in a 50°C oven for 2 days to cure, thereby being prepared.

[0021] Comparative Example 1: A method for preparing a polyurethane pressure-sensitive adhesive protective film, comprising the following steps: (1) trifluoropropyl cage polysilsesquioxane (trifluoropropyl-POSS) was dried in an 80℃ oven for 8h, and after drying, it was taken out and placed in a drying dish to cool for 12h to obtain modified POSS; (2) 100g of polyurethane adhesive was taken, 50g of ethyl acetate and 50g of toluene were added, and a high-speed mixer was used to stir at a speed of 3000 rad / min for 20min to obtain solution 1; (3) 3g of modified POSS of step (1) was added to solution 1, and a high-speed mixer was used to stir at a speed of 1500 rad / min for 25min to obtain suspension 1 after sufficient stirring; (4) 3g of isophorone diisocyanate curing agent was added to suspension 1, and a high-speed mixer was used to stir at a speed of 2000 rad / min for 15min to obtain a pressure-sensitive adhesive mixture after sufficient stirring; (5) The pressure-sensitive adhesive mixture was coated on a 50μm PET film using a 10μm doctor blade, and after drying in a 120℃ oven for 1min, the film was wound and then placed in a 40℃ oven for 3 days to obtain.

[0022] Comparative Example 2: A method for preparing a polyurethane pressure-sensitive adhesive protective film, comprising the following steps: (1) 100g of polyurethane adhesive was taken, 50g of ethyl acetate and 50g of toluene were added, and a high-speed mixer was used to stir at a speed of 3000 rad / min for 20min to obtain solution 1; (2) 7g of indium tin oxide (indium tin ratio 95:5) dispersion was added to solution 1, and a high-speed mixer was used to stir at a speed of 1500 rad / min for 25min to obtain suspension 1 after sufficient stirring; (3) 1.5g of isophorone diisocyanate curing agent was added to suspension 1, and a high-speed mixer was used to stir at a speed of 2000 rad / min for 15min to obtain a pressure-sensitive adhesive mixture after sufficient stirring; (4) The pressure-sensitive adhesive mixture was coated on a 50μm PET film using a 10μm doctor blade, and after drying in a 120℃ oven for 1min, the film was wound and then placed in a 40℃ oven for 3 days to obtain.

[0023] Comparative Example 3: A method for preparing a UV aging resistant polyurethane pressure-sensitive adhesive protective film, comprising the following steps: (1) cage polysilsesquioxane (POSS) was dried in an 80℃ oven for 8h, and after drying, it was taken out and placed in a drying dish to cool for 12h to obtain modified POSS; (2) Take 100 g of polyurethane adhesive, add 50 g of ethyl acetate and 50 g of toluene, use a high-speed mixer to stir at a speed of 3000 rad / min for 20 min, and obtain solution 1; (3) Add 7 g of indium tin oxide (indium-tin ratio 95:5) dispersion liquid to solution 1, use a high-speed mixer to stir at a speed of 1500 rad / min for 25 min, and obtain suspension 1 after sufficient stirring; (4) Add 1 g of POSS of step (1) to suspension 1, use a high-speed mixer to stir at a speed of 1500 rad / min for 25 min, and obtain suspension 2 after sufficient stirring; (5) Add 1.5 g of isoflurone diisocyanate curing agent to suspension 2, use a high-speed mixer to stir at a speed of 2000 rad / min for 15 min, and obtain pressure-sensitive adhesive mixed liquid after sufficient stirring; (6) Use a 10 μm doctor blade to coat the pressure-sensitive adhesive mixed liquid on a 50 μm PET film, dry it in a 120°C oven for 1 min, then roll it, and then put it in a 40°C oven for 3 days to obtain.

[0024] Test Example: The tested protective film substrates are all PET, the adhesive layer thickness is 10-15 μm, and the aging is carried out at 60°C for 3 days.

[0025] The polyurethane pressure-sensitive adhesive protective films prepared in Examples 1-3 and Comparative Examples 1-3 are placed in a UV aging oven for 60 h, then tested, the peeling strength is tested according to the peeling method in GB / T2792-2014, the transmittance of the polyurethane protective film before UV is tested according to GB / T 2410-2008, the Lab value of the polyurethane adhesive layer before and after UV irradiation is tested using a color difference meter to obtain Δb; the protective film is pasted to a steel plate and placed in a UV aging oven for 60 h, then visually observed whether there is adhesive layer residue and precipitation on the steel plate.

[0026] Table 1 Test results of polyurethane pressure-sensitive adhesive protective films prepared in Examples 1-3 and Comparative Examples 1-3

[0027] As shown in Table 1, the addition of functional fillers in Examples 1-3 does not cause a significant loss of optical performance of the protective film; the increase of the content of indium oxide can significantly improve the UV resistance of the adhesive layer, and the introduction of trifluoropropyl under the addition of indium tin oxide can absorb the free radicals generated after UV irradiation, preventing the yellowing of the polyurethane adhesive layer. Therefore, the synergistic effect of indium tin oxide and trifluoropropyl-POSS can effectively improve the UV resistance of the polyurethane adhesive layer.

[0028] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a UV-aging resistant polyurethane pressure sensitive adhesive protective film, characterized in that, The method comprises the following steps: (1) adding an organic solvent to a polyurethane adhesive, mixing to obtain solution 1; (2) adding an indium tin oxide dispersion liquid to the solution 1, mixing to obtain suspension 1; (3) adding trifluoropropyl cage silsesquioxane to the suspension 1, mixing to obtain suspension 2; (4) adding a curing agent to the suspension 2, mixing to obtain a pressure-sensitive adhesive mixture; (5) coating the pressure-sensitive adhesive mixture of step (4) on a film, drying to obtain a film, then rolling, and then aging to obtain a product.

2. The production method according to claim 1, characterized by, The polyurethane adhesive has a molecular weight of 25000-40000 g / mol, an isocyanate hard segment content of 20%-40%, and a hard segment in the main chain being an isocyanate containing a benzene ring, and a soft segment being a polyether polyol.

3. The preparation method according to claim 1, characterized in that, The organic solvent is at least one of acetone, butanone, methyl acetate, ethyl acetate, n-butyl acetate, toluene and xylene.

4. The method of claim 1, wherein, The indium tin ratio of the indium tin oxide dispersion liquid is 95-80:5-20.

5. The preparation method according to claim 1, characterized in that, The curing agent is an aliphatic polyisocyanate curing agent.

6. The preparation method according to claim 3, characterized in that, The aliphatic polyisocyanate curing agent comprises at least one of hydrogenated xylene diisocyanate, dicyclohexyl methane diisocyanate, isoflurane diisocyanate and hexamethyl diisocyanate.

7. The preparation method according to claim 1, characterized in that, The film is PET, PO, PI or PP.

8. The method of claim 1, wherein, The aging temperature is 40-60°C, and the aging time is 1-3 days.

9. The method of claim 1, wherein, The mass ratio of the polyurethane adhesive, the organic solvent, the indium tin oxide, the trifluoropropyl cage silsesquioxane and the curing agent is 100:20-50:0.5-10:1-5:0.5-3.

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