High-light-transmittance label protection film and preparation method thereof

Abstract

The invention relates to the technical field of protective films, in particular to a high-light-transmittance label protective film and a preparation method thereof.A multi-layer protective film formed by compounding a release film layer, an adhesive layer, a PET film and a protective layer is constructed; composite vinyl ester resin constructed by taking epoxy resin and acrylic acid as raw materials is subjected to toughening modification, and then a linear reactive diluent is compounded to construct a high-toughness protective layer which is resistant to high temperature and aging and can be photo-cured; long-chain alkane modified nano silicon dioxide is introduced into the protective coating, nano silicon dioxide is aminated by 3-aminopropyltriethoxysilane, and then 17-carbon monoisocyanate prepared by taking acetone, stearic acid, triphenylphosphine, sodium azide and N-chlorosuccinimide as raw materials is grafted to form the long-chain alkane modified nano silicon dioxide. Vinyl butadiene styrene rubber, composite vinyl ester resin, tackifying resin, a softening agent and a photoinitiator are mixed to prepare the adhesive layer.

Description

Technical Field

[0001] The present invention relates to the technical field of protective films, in particular to a high-light-transmittance label protective film and a preparation method thereof. Background Art

[0002] Labels are widely used in fields such as physics, chemistry, biology, education, and medical treatment, as well as in industries such as factories, mines, and pilot bases. Existing labels usually consist of self-adhesive label paper pasted on the surface of items. However, as the application time increases, the labels are prone to adhesiveness, especially in humid and high-temperature environments, which will accelerate the aging of the labels and cause the label information to be blurred.

[0003] Studying how to optimize the raw material composition and structure of label protective film to prepare a multifunctional label protective film with high light transmittance, aging resistance, water resistance, wear resistance, etc. has practical significance and economic value. Summary of the Invention

[0004] The object of the present invention is to provide a high-transmittance label protective film and a preparation method thereof, so as to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A high-transmittance label protective film, comprising a release film layer, an adhesive layer, a PET film and a protective layer in sequence; The raw materials of the adhesive layer are: vinyl styrene-butadiene rubber, composite vinyl ester resin, tackifying resin, softener, and photoinitiator; The raw materials of the protective layer are: composite vinyl ester resin, linear active diluent, auxiliary agent, long-chain alkane modified nano silicon dioxide and solvent.

[0006] Furthermore, the release film layer is one of PET release film, BOPP release film, PP release film and PE release film.

[0007] Furthermore, the raw material composition of the adhesive layer is, by weight, 10-15 parts of vinyl styrene-butadiene rubber, 6-8 parts of composite vinyl ester resin, 2-4 parts of tackifying resin, 1-3 parts of softener, and 0.5-1 part of photoinitiator.

[0008] Furthermore, the tackifying resin is terpene resin, and the softener is paraffin oil.

[0009] Furthermore, in the preparation of the protective layer, the mass ratio of the composite vinyl ester resin and the linear active diluent is 3:1, and the mass ratio of the composite vinyl ester resin and the long-chain alkane-modified nano-silica is 15:1; the auxiliary agent is a photoinitiator and a catalyst compounded in a mass ratio of 2:1; the mass ratio of the composite vinyl ester resin, the auxiliary agent, and the solvent is 15:0.9:8.

[0010] Further, the preparation of the composite vinyl ester resin comprises the following steps: (1) Under nitrogen atmosphere, octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane are mixed, kept at 58-62°C for 50-70 minutes, tetramethylammonium hydroxide silicon alkoxide and 1,4-bis(dimethylhydroxysilyl)benzene are added, the temperature is raised to 108-112°C and kept for 2-3 hours, heated to 148-152°C and kept under vacuum for 1-2 hours, and kept at 100°C for 2 hours to obtain terminal hydroxy vinyl phenylene polysiloxane; (2) Under a nitrogen atmosphere, hydroxy-terminated vinyl phenylene polysiloxane and triacrylic acid are mixed, 4-dimethylaminopyridine is added, the temperature is raised to keep warm for 4-6 hours, deionized water and dichloromethane are used as solvent and extractant, and extraction is carried out 3-5 times, and rotary evaporation is carried out to obtain carboxyl-terminated vinyl phenylene polysiloxane; (3) Under nitrogen atmosphere, epoxy resin, acrylic acid, and carboxyl-terminated vinylphenylene polysiloxane are mixed, tetrabutylammonium bromide and hydroquinone are added, and the mixture is kept at 85-90°C for 50-70 minutes, and then the temperature is raised to 108-110°C and kept for 1-2 hours to obtain a composite vinyl ester resin.

[0011] Furthermore, in the preparation of the composite vinyl ester resin, the molar ratio of the sum of the carboxyl groups in acrylic acid and the carboxyl-terminated vinylphenylene polysiloxane to the epoxy groups in the epoxy resin is 1.2:1; the mass ratio of the sum of the masses of acrylic acid and the carboxyl-terminated vinylphenylene polysiloxane to tetrabutylammonium bromide is 100:1; and the mass ratio of hydroquinone to acrylic acid is 1:500.

[0012] Furthermore, the preparation of long-chain alkane-modified nano-silica comprises the following steps: A. Mix deionized water, anhydrous ethanol, and 3-aminopropyltriethoxysilane, add nano-silica, stir for 3-5 minutes, let stand for 2-3 hours, keep warm at 120°C for 2 hours, wash, and dry to obtain amino-modified nano-silica; B. Mix acetone, stearic acid, triphenylphosphine, and sodium azide, cool to -11°C in an ice-salt bath, add a mixture of N-chlorosuccinimide and acetone, incubate for 2 hours, distill, add n-hexane, and distill under reduced pressure to obtain heptadecanocyanate. C. Under a nitrogen atmosphere, n-hexane, amino-modified nano-silica, dibutyltin dilaurate, and heptadecanoic acid monoisocyanate were mixed, heated to 43-47°C and kept warm for 1-2 hours, then heated to 78-82°C and kept warm for 3-4 hours, washed, and dried to obtain long-chain alkane-modified nano-silica.

[0013] Furthermore, the molar ratio of amino group to heptadecanoisocyanate in the amino-treated nano-silica is 2:1.

[0014] Furthermore, a method for preparing a high-transmittance label protective film comprises the following steps: S1: vinyl styrene-butadiene rubber, composite vinyl ester resin, tackifying resin, softener, and photoinitiator are mixed and stirred to obtain an adhesive coating liquid; S2: Apply the adhesive coating liquid on one side of the PET film, cover it with a release film layer, and perform light curing to form an adhesive layer; S3: mixing and stirring the composite vinyl ester resin, the linear active diluent, the long-chain alkane-modified nano-silica, the additive, and the solvent to obtain a protective coating; S4: applying a protective coating on the other side of the PET film and performing a light curing process to form a protective layer, thereby obtaining a highly light-transmitting label protective film.

[0015] Furthermore, the working conditions of the light curing treatment are: irradiation with an ultraviolet lamp at a wavelength of 365nm for 6-8s.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a high-light-transmittance label protective film and a preparation method thereof. Through component and process design, a multi-layer protective film composed of a release film layer, an adhesive layer, a PET film and a protective layer is constructed to prepare a high-light-transmittance label protective film that is hydrophobic, corrosion-resistant, wear-resistant and aging-resistant, thereby significantly extending the service life of the label.

[0017] In the present invention, PET film is used as a base film material, and a composite vinyl ester resin and a linear active diluent are blended to form a photocurable protective coating. The addition of the linear active diluent allows the polymer chains between the crosslinking points of the coating to rotate more freely, but it is difficult to avoid a reduction in the mechanical strength of the composite vinyl ester resin material. In the present invention, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and 1,4-bis(dimethylhydroxysilyl)benzene are first used as raw materials, and tetramethylammonium hydroxide siliconate is used as a catalyst to prepare a terminal hydroxyl vinyl phenylene polysiloxane with high thermal stability and heat aging resistance. Then, 4-dimethylaminopyridine is used as an esterification catalyst, and tris(propionic acid) is used as a capping modification material to prepare a terminal carboxyl vinyl phenylene polysiloxane. Then, the terminal carboxyl vinyl phenylene polysiloxane is used as a chain extender to toughen and modify the composite vinyl ester resin constructed from epoxy resin and acrylic acid as raw materials. Finally, a linear active diluent is compounded to construct a high-toughness protective layer that is both resistant to high temperature and aging and photocurable. In order to give the protective layer hydrophobicity and high light transmittance, long-chain alkane-modified nano-silica is introduced into the protective coating, wherein the long-chain alkane-modified nano-silica is ammoniated with 3-aminopropyltriethoxysilane to form nano-silica with the advantages of high hardness, low refractive index, good chemical stability, wear resistance and scratch resistance, and then grafted with 17-carbon monoisocyanate prepared from acetone, stearic acid, triphenylphosphine, sodium azide and N-chlorosuccinimide as raw materials; by controlling the preparation of composite vinyl ester resin, acrylic acid and terminal carboxyl The molar ratio of the sum of the carboxyl groups in the vinylphenylene polysiloxane to the epoxy groups in the epoxy resin allows the composite vinyl ester resin to contain carboxyl groups. In the preparation of the long-chain alkane-modified nano-silica, the feeding ratio of the amino-modified nano-silica and the heptadecanoisocyanate allows the amino groups in the long-chain alkane-modified nano-silica to react and graft the carboxyl groups in the composite vinyl ester resin, thereby greatly improving the uniformity and firmness of the dispersion of the long-chain alkane-modified nano-silica in the protective layer, and greatly improving the hydrophobicity, corrosion resistance, wear resistance and aging resistance of the protective layer.

[0018] In order to improve the adhesion of the base film in the present invention, vinyl styrene-butadiene rubber and composite vinyl ester resin are compounded as a light-curable glue, which is coated on the surface of the base film to form an adhesive layer that is resistant to acid and alkali corrosion, water resistance, weather resistance, and high temperature resistance, and covers the release film layer for protection and winding. DETAILED DESCRIPTION

[0019] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, such directional indications are only used to explain a specific posture, such as the relative position relationship between components, the movement status, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments may be combined with each other, but they must be based on the premise that they can be implemented by ordinary technicians in this field. If the combination of technical solutions is mutually inconsistent or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0021] The technical solutions of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely used to explain the present invention and are not intended to limit the present invention.

[0022] Example 1: A method for preparing a high-transmittance label protective film, comprising the following steps: S1: vinyl styrene-butadiene rubber, composite vinyl ester resin, tackifying resin, softener, and photoinitiator are mixed and stirred to obtain an adhesive coating liquid; S2: Apply the adhesive coating liquid on one side of the PET film, cover it with a release film layer, and perform light curing to form an adhesive layer; The raw material composition of the adhesive layer is as follows, by mass: 10 parts of vinyl styrene-butadiene rubber, 6 parts of composite vinyl ester resin, 2 parts of tackifying resin, 1 part of softener, and 0.5 parts of photoinitiator; the tackifying resin is terpene resin, and the softener is paraffin oil; The preparation of the composite vinyl ester resin comprises the following steps: (1) Under nitrogen atmosphere, 8.9 g of octamethylcyclotetrasiloxane and 4.3 g of tetramethyltetravinylcyclotetrasiloxane were mixed and kept at 58 °C for 70 min. 0.2 g of tetramethylammonium hydroxide silicon alkoxide and 1.7 g of 1,4-bis(dimethylhydroxysilyl)benzene were added. The temperature was raised to 108 °C and kept for 3 h. The temperature was then heated to 148 °C and kept under vacuum for 2 h. The temperature was then kept at 100 °C for 2 h to obtain terminal hydroxy vinyl phenylene polysiloxane. (2) Under nitrogen atmosphere, hydroxy-terminated vinyl phenylene polysiloxane and triacrylic acid were mixed, 4-dimethylaminopyridine was added, the temperature was raised to 115°C and kept warm for 4 hours, deionized water and dichloromethane were used as solvent and extractant, and extraction was performed three times, and rotary evaporation was performed to obtain carboxyl-terminated vinyl phenylene polysiloxane; The molar ratio of 4-dimethylaminopyridine, hydroxy-terminated vinylphenylene polysiloxane, and triacylglycerol is 1.5%:1:3; (3) Under nitrogen atmosphere, epoxy resin, acrylic acid, and carboxyl-terminated vinyl phenylene polysiloxane were mixed, tetrabutylammonium bromide and hydroquinone were added, and the mixture was kept at 85°C for 70 minutes, and then heated to 108°C for 2 hours to obtain a composite vinyl ester resin; In the preparation of the composite vinyl ester resin, the molar ratio of the sum of the carboxyl groups in the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to the epoxy groups in the epoxy resin is 1.2:1; the mass ratio of the sum of the mass of the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to tetrabutylammonium bromide is 100:1; and the mass ratio of hydroquinone to acrylic acid is 1:500. S3: mixing and stirring the composite vinyl ester resin, the linear active diluent, the long-chain alkane-modified nano-silica, the additive, and the solvent to obtain a protective coating; The mass ratio of the composite vinyl ester resin and the linear reactive diluent is 3:1, the mass ratio of the composite vinyl ester resin and the long-chain alkane-modified nano-silica is 15:1; the auxiliary agent is a photoinitiator and a catalyst compounded in a mass ratio of 2:1; the mass ratio of the composite vinyl ester resin, the auxiliary agent, and the solvent is 15:0.9:8; The preparation of the long-chain alkane-modified nano-silica comprises the following steps: A. Mix 1 mL of deionized water, 4 mL of anhydrous ethanol, and 1 g of 3-aminopropyltriethoxysilane, add 1 g of nano-silica, stir for 3 minutes, let stand for 2 hours, keep at 120°C for 2 hours, wash, and dry to obtain amino-modified nano-silica; B. Mix 15 mL of acetone, 2.6 g of stearic acid, 2.8 g of triphenylphosphine, and 1.3 g of sodium azide, cool to -11°C in an ice-salt bath, add 1.3 g of N-chlorosuccinimide and 20 mL of acetone, incubate for 2 h, distill, add to 15 mL of n-hexane, and distill under reduced pressure to obtain heptadecanocyanate. C. Under a nitrogen atmosphere, n-hexane, amino-modified nano-silica, dibutyltin dilaurate, and heptadecanoic acid monoisocyanate were mixed, heated to 43°C and kept for 2 hours, then heated to 78°C and kept for 4 hours, washed, and dried to obtain long-chain alkane-modified nano-silica; The molar ratio of amino group to heptadecanoisocyanate in the amino nano-silica is 2:1; the mass ratio of amino nano-silica to dibutyltin dilaurate is 100:3; S4: applying a protective coating on the other side of the PET film and performing a light curing process to form a protective layer to obtain a highly light-transmitting label protective film; The working conditions of the light curing treatment are: irradiation with an ultraviolet lamp of a wavelength of 365 nm for 6 seconds; the release film layer is a PET release film.

[0023] Example 2: A method for preparing a high-transmittance label protective film, comprising the following steps: S1: vinyl styrene-butadiene rubber, composite vinyl ester resin, tackifying resin, softener, and photoinitiator are mixed and stirred to obtain an adhesive coating liquid; S2: Apply the adhesive coating liquid on one side of the PET film, cover it with a release film layer, and perform light curing to form an adhesive layer; The raw material composition of the adhesive layer is as follows, by weight: 12 parts of vinyl styrene-butadiene rubber, 7 parts of composite vinyl ester resin, 3 parts of tackifying resin, 2 parts of softener, and 0.8 parts of photoinitiator; the tackifying resin is terpene resin, and the softener is paraffin oil; The preparation of the composite vinyl ester resin comprises the following steps: (1) Under nitrogen atmosphere, 8.9 g of octamethylcyclotetrasiloxane and 4.3 g of tetramethyltetravinylcyclotetrasiloxane were mixed and kept at 60 °C for 60 min. 0.2 g of tetramethylammonium hydroxide silicon alkoxide and 1.7 g of 1,4-bis(dimethylhydroxysilyl)benzene were added. The mixture was heated to 110 °C and kept for 2.5 h. The mixture was then heated to 150 °C and kept under vacuum for 1.5 h. The mixture was then kept at 100 °C for 2 h to obtain terminal hydroxy vinyl phenylene polysiloxane. (2) Under nitrogen atmosphere, hydroxy-terminated vinyl phenylene polysiloxane and triacrylic acid were mixed, 4-dimethylaminopyridine was added, the temperature was raised to 115°C and kept warm for 5 hours, deionized water and dichloromethane were used as solvent and extractant, and the mixture was extracted 4 times, and rotary evaporation was performed to obtain carboxyl-terminated vinyl phenylene polysiloxane; The molar ratio of 4-dimethylaminopyridine, hydroxy-terminated vinylphenylene polysiloxane, and triacylglycerol is 1.5%:1:3; (3) Under nitrogen atmosphere, epoxy resin, acrylic acid, and carboxyl-terminated vinyl phenylene polysiloxane were mixed, tetrabutylammonium bromide and hydroquinone were added, and the mixture was kept at 88°C for 60 minutes, and then heated to 109°C for 1.5 hours to obtain a composite vinyl ester resin; In the preparation of the composite vinyl ester resin, the molar ratio of the sum of the carboxyl groups in the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to the epoxy groups in the epoxy resin is 1.2:1; the mass ratio of the sum of the mass of the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to tetrabutylammonium bromide is 100:1; and the mass ratio of hydroquinone to acrylic acid is 1:500. S3: mixing and stirring the composite vinyl ester resin, the linear active diluent, the long-chain alkane-modified nano-silica, the additive, and the solvent to obtain a protective coating; The mass ratio of the composite vinyl ester resin and the linear reactive diluent is 3:1, the mass ratio of the composite vinyl ester resin and the long-chain alkane-modified nano-silica is 15:1; the auxiliary agent is a photoinitiator and a catalyst compounded in a mass ratio of 2:1; the mass ratio of the composite vinyl ester resin, the auxiliary agent, and the solvent is 15:0.9:8; The preparation of the long-chain alkane-modified nano-silica comprises the following steps: A. Mix 1 mL of deionized water, 4 mL of anhydrous ethanol, and 1 g of 3-aminopropyltriethoxysilane, add 1 g of nano-silica, stir for 4 minutes, let stand for 2.5 hours, keep at 120°C for 2 hours, wash, and dry to obtain amino-modified nano-silica; B. Mix 15 mL of acetone, 2.6 g of stearic acid, 2.8 g of triphenylphosphine, and 1.3 g of sodium azide, cool to -11°C in an ice-salt bath, add 1.3 g of N-chlorosuccinimide and 20 mL of acetone, incubate for 2 h, distill, add to 15 mL of n-hexane, and distill under reduced pressure to obtain heptadecanocyanate. C. Under a nitrogen atmosphere, n-hexane, amino-modified nano-silica, dibutyltin dilaurate, and heptadecanoic acid monoisocyanate were mixed, heated to 45°C and kept for 1.5 hours, then heated to 80°C and kept for 3.5 hours, washed, and dried to obtain long-chain alkane-modified nano-silica; The molar ratio of amino group to heptadecanoisocyanate in the amino nano-silica is 2:1; the mass ratio of amino nano-silica to dibutyltin dilaurate is 100:3; S4: applying a protective coating on the other side of the PET film and performing a light curing process to form a protective layer to obtain a highly light-transmitting label protective film; The working conditions of the light curing treatment are: irradiation with an ultraviolet lamp of a wavelength of 365 nm for 7 seconds; the release film layer is a PET release film.

[0024] Example 3: A method for preparing a high-transmittance label protective film, comprising the following steps: S1: vinyl styrene-butadiene rubber, composite vinyl ester resin, tackifying resin, softener, and photoinitiator are mixed and stirred to obtain an adhesive coating liquid; S2: Apply the adhesive coating liquid on one side of the PET film, cover it with a release film layer, and perform light curing to form an adhesive layer; The raw material composition of the adhesive layer is as follows, by mass: 15 parts of vinyl styrene-butadiene rubber, 8 parts of composite vinyl ester resin, 4 parts of tackifying resin, 3 parts of softener, and 1 part of photoinitiator; the tackifying resin is terpene resin, and the softener is paraffin oil; The preparation of the composite vinyl ester resin comprises the following steps: (1) Under nitrogen atmosphere, 8.9 g of octamethylcyclotetrasiloxane and 4.3 g of tetramethyltetravinylcyclotetrasiloxane were mixed and kept at 62 °C for 50 min. 0.2 g of tetramethylammonium hydroxide silicon alkoxide and 1.7 g of 1,4-bis(dimethylhydroxysilyl)benzene were added. The temperature was raised to 112 °C and kept for 2 h. The temperature was then heated to 152 °C and kept under vacuum for 1 h. The temperature was then kept at 100 °C for 2 h to obtain terminal hydroxy vinyl phenylene polysiloxane. (2) Under nitrogen atmosphere, hydroxy-terminated vinyl phenylene polysiloxane and triacrylic acid were mixed, 4-dimethylaminopyridine was added, the temperature was raised to 115°C and kept warm for 6 hours, deionized water and dichloromethane were used as solvent and extractant, and extraction was carried out 5 times, and rotary evaporation was carried out to obtain carboxyl-terminated vinyl phenylene polysiloxane; The molar ratio of 4-dimethylaminopyridine, hydroxy-terminated vinylphenylene polysiloxane, and triacylglycerol is 1.5%:1:3; (3) Under nitrogen atmosphere, epoxy resin, acrylic acid, and carboxyl-terminated vinyl phenylene polysiloxane were mixed, tetrabutylammonium bromide and hydroquinone were added, and the mixture was kept at 90°C for 50 minutes, and then heated to 110°C for 1 hour to obtain a composite vinyl ester resin; In the preparation of the composite vinyl ester resin, the molar ratio of the sum of the carboxyl groups in the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to the epoxy groups in the epoxy resin is 1.2:1; the mass ratio of the sum of the mass of the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to tetrabutylammonium bromide is 100:1; and the mass ratio of hydroquinone to acrylic acid is 1:500. S3: mixing and stirring the composite vinyl ester resin, the linear active diluent, the long-chain alkane-modified nano-silica, the additive, and the solvent to obtain a protective coating; The mass ratio of the composite vinyl ester resin and the linear reactive diluent is 3:1, the mass ratio of the composite vinyl ester resin and the long-chain alkane-modified nano-silica is 15:1; the auxiliary agent is a photoinitiator and a catalyst compounded in a mass ratio of 2:1; the mass ratio of the composite vinyl ester resin, the auxiliary agent, and the solvent is 15:0.9:8; The preparation of the long-chain alkane-modified nano-silica comprises the following steps: A. Mix 1 mL of deionized water, 4 mL of anhydrous ethanol, and 1 g of 3-aminopropyltriethoxysilane, add 1 g of nano-silica, stir for 5 minutes, let stand for 2 hours, keep at 120°C for 2 hours, wash, and dry to obtain amino-modified nano-silica; B. Mix 15 mL of acetone, 2.6 g of stearic acid, 2.8 g of triphenylphosphine, and 1.3 g of sodium azide, cool to -11°C in an ice-salt bath, add 1.3 g of N-chlorosuccinimide and 20 mL of acetone, incubate for 2 h, distill, add to 15 mL of n-hexane, and distill under reduced pressure to obtain heptadecanocyanate. C. Under a nitrogen atmosphere, n-hexane, amino-modified nano-silica, dibutyltin dilaurate, and heptadecanocyanate were mixed, heated to 47°C for 1 hour, then heated to 82°C for 3 hours, washed, and dried to obtain long-chain alkane-modified nano-silica; The molar ratio of amino group to heptadecanoisocyanate in the amino nano-silica is 2:1; the mass ratio of amino nano-silica to dibutyltin dilaurate is 100:3; S4: applying a protective coating on the other side of the PET film and performing a light curing process to form a protective layer to obtain a highly light-transmitting label protective film; The working conditions of the light curing treatment are: irradiation with an ultraviolet lamp of a wavelength of 365 nm for 8 seconds; the release film layer is a PET release film.

[0025] Comparative Example 1: Taking Example 3 as the control group, the composite vinyl ester resin was replaced by composite vinyl ester resin VER-2 (98%: Hubei Xinmingtai Chemical Co., Ltd.), and the other processes were normal.

[0026] Comparative Example 2: Taking Example 3 as the control group, nano-silica was used to replace the long-chain alkane to modify the nano-silica, and the other processes were normal.

[0027] Comparative Example 3: Taking Example 3 as the control group, in the preparation of the composite vinyl ester resin, the molar ratio of the sum of the carboxyl groups in the acrylic acid and the carboxyl-terminated vinylphenylene polysiloxane to the epoxy groups in the epoxy resin was 1:1, and the other processes were normal.

[0028] In the embodiments and comparative examples: The preparation of tetramethylammonium hydroxide silicon alkoxide comprises the following steps: 0.4 g of tetramethylammonium hydroxide pentahydrate and 20 g of octamethylcyclotetrasiloxane were mixed, and the temperature was raised to 60° C. and kept for 1 h under a vacuum degree of -0.09 MPa, and then raised to 80° C. and kept for 4 h to obtain tetramethylammonium hydroxide siliconate with a mass fraction of 2%.

[0029] The catalysts in the examples and comparative examples are N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride prepared in a mass ratio of 1:1.

[0030] The thickness of the protective layer and the adhesive layer in the embodiment and the comparative example is 10 μm.

[0031] Sources of raw materials used (for demonstration purposes only): Vinyl styrene-butadiene rubber SSBR2466: Taiwan Rubber Corporation; Terpene resin XK7965: Hubei Xinkang Pharmaceutical Chemical Co., Ltd.; Paraffin oil (99%): Hubei Xinhongli Chemical Co., Ltd. PET release film (20µm): Shenzhen Ruichangxing Technology Co., Ltd.; transparent PET film (25µm): Suzhou Xiangrong Electronic Technology Co., Ltd.; epoxy resin E51 (99%): Jinan Chuangshi Chemical Co., Ltd.; photoinitiator (1173, 99%): Hubei Zhenbo Chemical Co., Ltd.; triacyl acrylate Y46878: Shanghai Yuanye Biotechnology Co., Ltd.; sodium azide S2002: Merck reagent; octamethylcyclotetrasiloxane O160041, tetramethyltetravinylcyclotetrasiloxane T162569, tetramethylammonium hydroxide pentahydrate T105041, 1,4-bis(dimethylhydroxysilyl)benzene P192482, acrylic acid A103526, tetrabutylammonium hydroxide pentahydrate Ammonium bromide T103372, hydroquinone H108945, linear active diluent (hydroxyethyl acrylate) H104535, N-hydroxysuccinimide H109330, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride E106172, 3-aminopropyltriethoxysilane A107147, nanosilica S104596, stearic acid S754992, triphenylphosphine T104475, N-chlorosuccinimide C105072, dibutyltin dilaurate D100274: Aladdin reagent; solvent (dimethylformamide), 4-dimethylaminopyridine, dichloromethane, ethanol, acetone, n-hexane, analytical grade, commercially available.

[0032] Performance test: The protective films prepared in the examples and comparative examples were tested: Light transmittance: The average transmittance in the 300-800nm ​​band was tested. Hydrophobicity: The water contact angle of the protective layer was measured using a contact angle meter and tested with a 2μL deionized water droplet. Heat aging resistance: The sample was kept at 120°C for 12 hours and observed for signs of hardening, brittleness, or damage. If no signs appeared, it was qualified; otherwise, it was unqualified. Corrosion resistance: The sample was placed in a 5% sodium chloride aqueous solution at 25°C for 72 hours, removed and dried, and then observed for signs of blistering or damage. If no signs appeared, it was qualified; otherwise, it was unqualified. The results are shown in Table 1. Table 1

[0033] The present invention provides a high-light-transmittance label protective film and a preparation method thereof. Through component and process design, a multilayer protective film composed of a release film layer, an adhesive layer, a PET film, and a protective layer is constructed to prepare a hydrophobic, corrosion-resistant, wear-resistant, and aging-resistant high-light-transmittance label protective film, thereby significantly extending the service life of the label. In Table 1, / indicates untested.

[0034] Comparing Example 3 with Comparative Example 1, it can be seen that in the present invention, PET film is used as the base film material, and a composite vinyl ester resin and a linear active diluent are blended to form a photocurable protective coating. The addition of the linear active diluent makes the polymer chain between the cross-linking points of the coating rotate more freely, but it is difficult to avoid a decrease in the mechanical strength of the composite vinyl ester resin material. In the present invention, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and 1,4-bis(dimethylhydroxysilyl)benzene are first used as raw materials, and tetramethylammonium hydroxide silicon alkoxide is used as a catalyst to prepare a terminal hydroxyl vinyl phenylene polysiloxane with high thermal stability and heat aging resistance. Then, 4-dimethylaminopyridine is used as an esterification catalyst and triacrylic acid is used as a capping modification material to prepare a terminal carboxyl vinyl phenylene polysiloxane. Then, the terminal carboxyl vinyl phenylene polysiloxane is used as a chain extender to toughen and modify the composite vinyl ester resin constructed from epoxy resin and acrylic acid as raw materials. Finally, a linear active diluent is compounded to construct a high-toughness protective layer that is both resistant to high temperature and aging and can be photocured. By comparing Example 3 with Comparative Example 2, it can be seen that in order to impart hydrophobicity and high light transmittance to the protective layer, long-chain alkane-modified nano-silica is introduced into the protective coating, wherein the long-chain alkane-modified nano-silica is prepared by amination of nano-silica having the advantages of high hardness, low refractive index, good chemical stability, wear resistance and scratch resistance with 3-aminopropyltriethoxysilane, and then grafting heptadecanoisocyanate prepared from acetone, stearic acid, triphenylphosphine, sodium azide and N-chlorosuccinimide as raw materials.

[0035] By comparing Example 3 with Comparative Example 3, it can be seen that by controlling the molar ratio of the sum of the carboxyl groups in acrylic acid and terminal carboxyl vinyl phenylene polysiloxane to the epoxy groups in the epoxy resin in the preparation of the composite vinyl ester resin, the composite vinyl ester resin contains carboxyl groups, and in the preparation of the long-chain alkane-modified nano-silica, the feeding ratio of the amino-type nano-silica and the heptadecanoisocyanate is controlled so that the amino groups in the long-chain alkane-modified nano-silica react and graft the carboxyl groups in the composite vinyl ester resin, thereby greatly improving the uniformity and firmness of the dispersion of the long-chain alkane-modified nano-silica in the protective layer, and greatly improving the hydrophobicity, corrosion resistance, wear resistance and aging resistance of the protective layer.

[0036] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification under the inventive concept of the present invention, or any direct / indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A high light transmittance label protective film, characterized in that: It includes a release film layer, an adhesive layer, a PET film and a protective layer in sequence; The raw materials of the adhesive layer are: vinyl styrene-butadiene rubber, composite vinyl ester resin, tackifying resin, softener, and photoinitiator; The raw materials of the protective layer are: composite vinyl ester resin, linear active diluent, auxiliary agent, long-chain alkane modified nano silicon dioxide and solvent.

2. The high-transmittance label protective film according to claim 1, characterized in that: The release film layer is one of PET release film, BOPP release film, PP release film and PE release film.

3. The high-transmittance label protective film according to claim 1, characterized in that: The raw material composition of the adhesive layer is as follows, in parts by mass: 10-15 parts of vinyl styrene-butadiene rubber, 6-8 parts of composite vinyl ester resin, 2-4 parts of tackifying resin, 1-3 parts of softener, and 0.5-1 part of photoinitiator.

4. The high-transmittance label protective film according to claim 1, characterized in that: In the protective layer, the mass ratio of the composite vinyl ester resin and the linear active diluent is 3:1, and the mass ratio of the composite vinyl ester resin and the long-chain alkane-modified nano-silica is 15:1; the auxiliary agent is a photoinitiator and a catalyst compounded in a mass ratio of 2:1; the mass ratio of the composite vinyl ester resin, the auxiliary agent and the solvent is 15:0.9:

8.

5. The high-transmittance label protective film according to claim 1, characterized in that: The preparation of the composite vinyl ester resin comprises the following steps: (1) Under nitrogen atmosphere, octamethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane are mixed, kept at 58-62°C for 50-70 minutes, tetramethylammonium hydroxide silicon alkoxide and 1,4-bis(dimethylhydroxysilyl)benzene are added, the temperature is raised to 108-112°C and kept for 2-3 hours, heated to 148-152°C and kept under vacuum for 1-2 hours, and kept at 100°C for 2 hours to obtain terminal hydroxy vinyl phenylene polysiloxane; (2) Under a nitrogen atmosphere, hydroxy-terminated vinyl phenylene polysiloxane and triacrylic acid are mixed, 4-dimethylaminopyridine is added, the temperature is raised to keep warm for 4-6 hours, deionized water and dichloromethane are used as solvent and extractant, and extraction is carried out 3-5 times, and rotary evaporation is carried out to obtain carboxyl-terminated vinyl phenylene polysiloxane; (3) Under nitrogen atmosphere, epoxy resin, acrylic acid, and carboxyl-terminated vinylphenylene polysiloxane are mixed, tetrabutylammonium bromide and hydroquinone are added, and the mixture is kept at 85-90°C for 50-70 minutes, and then the temperature is raised to 108-110°C and kept for 1-2 hours to obtain a composite vinyl ester resin.

6. The high-transmittance label protective film according to claim 5, characterized in that: In the preparation of the composite vinyl ester resin, the molar ratio of the sum of the carboxyl groups in the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to the epoxy groups in the epoxy resin is 1.2:1; the mass ratio of the sum of the masses of the acrylic acid and the carboxyl-terminated vinyl phenylene polysiloxane to tetrabutylammonium bromide is 100:1; and the mass ratio of hydroquinone to acrylic acid is 1:

500.

7. The high-transmittance label protective film according to claim 1, characterized in that: The preparation of the long-chain alkane-modified nano-silica comprises the following steps: A. Mix deionized water, anhydrous ethanol, and 3-aminopropyltriethoxysilane, add nano-silica, stir for 3-5 minutes, let stand for 2-3 hours, keep warm at 120°C for 2 hours, wash, and dry to obtain amino-modified nano-silica; B. Mix acetone, stearic acid, triphenylphosphine, and sodium azide, cool to -11°C in an ice-salt bath, add a mixture of N-chlorosuccinimide and acetone, incubate for 2 hours, distill, add n-hexane, and distill under reduced pressure to obtain heptadecanocyanate. C. Under a nitrogen atmosphere, n-hexane, amino-modified nano-silica, dibutyltin dilaurate, and heptadecanoic acid monoisocyanate were mixed, heated to 43-47°C and kept warm for 1-2 hours, then heated to 78-82°C and kept warm for 3-4 hours, washed, and dried to obtain long-chain alkane-modified nano-silica.

8. The high-transmittance label protective film according to claim 7, characterized in that: The molar ratio of amino groups to heptadecanoyl monoisocyanate in the amino-treated nano-silica is 2:

1.

9. A method for preparing a high-transmittance label protective film according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: vinyl styrene-butadiene rubber, composite vinyl ester resin, tackifying resin, softener, and photoinitiator are mixed and stirred to obtain an adhesive coating liquid; S2: Apply the adhesive coating liquid on one side of the PET film, cover it with a release film layer, and perform light curing to form an adhesive layer; S3: mixing and stirring the composite vinyl ester resin, the linear active diluent, the long-chain alkane-modified nano-silica, the additive, and the solvent to obtain a protective coating; S4: applying a protective coating on the other side of the PET film and performing a light curing process to form a protective layer, thereby obtaining a highly light-transmitting label protective film.

10. The method for preparing a high-transmittance label protective film according to claim 9, characterized in that: The working conditions of the light curing treatment are: irradiation with ultraviolet light at a wavelength of 365nm for 6-8s.

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