Composite anti-UV master batch, anti-UV transparent heat shrink film, and preparation method and application of anti-UV transparent heat shrink film

Abstract

The invention provides a composite anti-UV master batch, an anti-UV transparent heat shrink film and a preparation method and application of the anti-UV transparent heat shrink film, and belongs to the technical field of film materials. The preparation method comprises the following steps: mixing cyanuric chloride, sulfanilic acid and water, carrying out a first reaction, adjusting the pH value of an obtained first product feed liquid to 8-9, mixing the first product feed liquid with a soluble zinc salt solution and ethidene diamine, carrying out a second reaction, adjusting the pH value of an obtained second product feed liquid to 8-9, and obtaining a precursor material; the precursor material comprises a triazine ultraviolet light absorber and nano zinc hydroxide loaded on the triazine ultraviolet light absorber; and mixing the precursor material with polyester, carrying out extrusion granulation under a heating condition, and decomposing the nano-zinc hydroxide to form nano-zinc oxide, thereby obtaining the composite anti-UV master batch. The anti-UV transparent heat shrink film prepared from the composite anti-UV master batch provided by the invention can effectively block ultraviolet light with the wave band in the range of 280-410nm.

Description

Technical Field

[0001] The invention relates to the technical field of film materials, and in particular to a composite anti-UV masterbatch and an anti-UV transparent heat shrinkable film, and a preparation method and application thereof. Background Art

[0002] Dairy products and medicines usually require the use of milky white polyethylene terephthalate (PET) bottles as containers to block ultraviolet rays due to the special nutrients in them being easily decomposed by ultraviolet rays. However, milky white PET bottles are expensive and difficult to recycle after use.

[0003] Transparent PET bottles are relatively low in cost. When using them as containers for dairy products and medicines, a layer of label can be wrapped around the transparent PET bottle to block ultraviolet light. Polyester (PETG) heat shrink film has the characteristics of high strength, good transparency, high gloss and adjustable shrinkage. It is widely used in food, such as juice, functional drinks, dairy products, etc., as well as outer wrapping labels for daily chemicals and medicines. PETG heat shrink film includes white PETG heat shrink film and transparent PETG heat shrink film. White PETG heat shrink film is relatively expensive and has a limited scope of application. For example, some products need to see the product through the label; traditional transparent PETG heat shrink film has poor blocking effect on ultraviolet light with a wavelength of more than 380nm. Summary of the invention

[0004] The purpose of the present invention is to provide a composite anti-UV masterbatch and an anti-UV transparent heat shrinkable film and a preparation method and application thereof. The anti-UV transparent heat shrinkable film prepared by using the composite anti-UV masterbatch provided by the present invention can effectively block ultraviolet light in the wavelength range of 280~410nm.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for preparing a composite anti-UV masterbatch, comprising the following steps: Mixing cyanuric chloride, p-aminobenzenesulfonic acid and water to carry out a first reaction to obtain a first product liquid; The first product solution is adjusted to a pH value of 8 to 9, and then mixed with a soluble zinc salt solution and ethylenediamine to perform a second reaction, and then the pH value of the obtained second product solution is adjusted to 8 to 9 to obtain a precursor material, wherein the precursor material includes a triazine ultraviolet absorber and nano zinc hydroxide supported on the triazine ultraviolet absorber; The precursor material is mixed with polyester, extruded and granulated under heating conditions, and the nano zinc hydroxide is decomposed to form nano zinc oxide, so as to obtain the composite anti-UV masterbatch.

[0006] Preferably, the mass ratio of cyanuric chloride to para-aminobenzenesulfonic acid is 50:45-51; the temperature of the first reaction is 0-5°C, and the time is 1-2h; The soluble zinc salt in the soluble zinc salt solution includes zinc nitrate, zinc chloride or zinc sulfate, the mass ratio of cyanuric chloride, soluble zinc salt and ethylenediamine is 50:8-12:45-55; the temperature of the second reaction is 45-55°C, and the time is 1.5-2.5h.

[0007] Preferably, the temperature of the extrusion granulation is 215-225°C.

[0008] The present invention provides a composite anti-UV masterbatch prepared by the preparation method described in the above technical scheme, comprising a polyester matrix and an anti-UV composite dispersed in the polyester matrix, wherein the anti-UV composite comprises a triazine ultraviolet absorber and nano zinc oxide loaded on the triazine ultraviolet absorber.

[0009] Preferably, the content of the anti-UV compound in the composite anti-UV masterbatch is 25-35wt%.

[0010] The present invention provides an anti-UV transparent heat shrinkable film, comprising a first surface layer, a core layer and a second surface layer which are stacked in sequence; the first surface layer and the second surface layer comprise a polyester matrix and an anti-blocking agent dispersed in the resin matrix; the core layer comprises a polyester matrix and a composite anti-UV masterbatch dispersed in the polyester matrix, and the composite anti-UV masterbatch is the composite anti-UV masterbatch described in the above technical solution.

[0011] Preferably, the thickness of the UV resistant transparent heat shrinkable film is 30-50 μm, and the thickness of the core layer is 80-90% of the thickness of the UV resistant transparent heat shrinkable film.

[0012] Preferably, the opening agent in the first surface layer and the second surface layer independently comprises nano-silicon dioxide and / or acid amide, the content of the opening agent in the first surface layer and the second surface layer is independently 1-3wt%, and the content of the composite anti-UV masterbatch in the core layer is 3-5wt%.

[0013] The present invention provides a method for preparing the UV-resistant transparent heat shrinkable film described in the above technical solution, comprising the following steps: According to the composition and ingredients of the first surface layer, the core layer and the second surface layer in the anti-UV transparent heat shrinkable film, the anti-UV transparent heat shrinkable film is obtained by sequentially undergoing melt plasticization, co-extrusion, cast film and stretching.

[0014] The present invention provides the use of the UV-resistant transparent heat shrinkable film described in the above technical solution or the UV-resistant transparent heat shrinkable film prepared by the preparation method described in the above technical solution in labels.

[0015] The present invention provides a method for preparing a composite anti-UV masterbatch, comprising the following steps: mixing cyanuric chloride, p-aminobenzenesulfonic acid and water, performing a first reaction, and obtaining a first product liquid; adjusting the pH value of the first product liquid to 8-9, and then mixing it with a soluble zinc salt solution and ethylenediamine, and performing a second reaction, and then adjusting the pH value of the obtained second product liquid to 8-9, to obtain a precursor material, wherein the precursor material comprises a triazine ultraviolet absorber and nano zinc hydroxide supported on the triazine ultraviolet absorber; mixing the precursor material with polyester, performing extrusion granulation under heating conditions, and decomposing the nano zinc hydroxide to form nano zinc oxide, to obtain the composite anti-UV masterbatch. The composite anti-UV masterbatch prepared by the method of the present invention comprises a polyester matrix and an anti-UV composite dispersed in the polyester matrix, wherein the anti-UV composite comprises a triazine ultraviolet absorber and nano zinc oxide supported on the triazine ultraviolet absorber. The ultraviolet absorption wavelength of the triazine ultraviolet absorber described in the present invention is 280~380nm, and the nano zinc oxide can produce a blocking effect on visible light above 350nm, especially above 410nm, and the triazine ultraviolet absorber described in the present invention can be used as a dispersant for nano zinc oxide, which prevents the agglomeration of nano zinc oxide to a certain extent, ensuring that it fully exerts its blocking effect. Therefore, the composite anti-UV masterbatch provided by the present invention combines the blocking effect of nano zinc oxide and the absorption effect of the triazine ultraviolet absorber, and is used in an anti-UV transparent heat shrink film, which has a good blocking effect on ultraviolet light with a wavelength of 280~410nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The UV light transmittance of the UV-resistant transparent heat shrinkable films prepared in various embodiments and comparative examples in different bands is shown. DETAILED DESCRIPTION

[0017] The present invention provides a method for preparing a composite anti-UV masterbatch, comprising the following steps: Mixing cyanuric chloride, p-aminobenzenesulfonic acid and water to carry out a first reaction to obtain a first product liquid; The first product solution is adjusted to a pH value of 8 to 9, and then mixed with a soluble zinc salt solution and ethylenediamine to perform a second reaction, and then the pH value of the obtained second product solution is adjusted to 8 to 9 to obtain a precursor material, wherein the precursor material includes a triazine ultraviolet absorber and nano zinc hydroxide supported on the triazine ultraviolet absorber; The precursor material is mixed with polyester, extruded and granulated under heating conditions, and the nano zinc hydroxide is decomposed to form nano zinc oxide, so as to obtain the composite anti-UV masterbatch.

[0018] The ultraviolet absorption wavelength of triazine ultraviolet absorbers can only reach 280~380nm, but for some special application scenarios, the absorption wavelength range of 380~410nm cannot be met. Nano zinc oxide added to the film material will have a blocking effect on visible light above 350nm, especially above 410nm, but ordinary nano zinc oxide is prone to agglomeration due to its inorganic particles. The anti-UV composite in the composite anti-UV masterbatch prepared by the method of the present invention includes a triazine ultraviolet absorber and nano zinc oxide loaded on the triazine ultraviolet absorber. The triazine ultraviolet absorber in the present invention can be used as a dispersant for nano zinc oxide, which prevents the agglomeration of nano zinc oxide to a certain extent, ensuring that it fully exerts its blocking effect. Therefore, the composite anti-UV masterbatch provided by the present invention combines the blocking effect of nano zinc oxide and the absorption effect of triazine ultraviolet absorbers, and the superposition of the two has a good blocking effect on ultraviolet light with a wavelength of 280~410nm. The preparation method of the composite anti-UV masterbatch provided by the present invention is described in detail below.

[0019] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art.

[0020] The present invention mixes cyanuric chloride, p-aminobenzenesulfonic acid and water, performs a first reaction, and obtains a first product liquid. As an embodiment of the present invention, the mass ratio of cyanuric chloride to p-aminobenzenesulfonic acid can be 50:45-51, specifically 50:45, 50:46, 50:47, 50:48, 50:49, 50:50 or 50:51; the mass ratio of cyanuric chloride to water can be 50:380-420, further 50:390-410, specifically 50:400, and the water can be ice water (temperature 0-5°C). As an embodiment of the present invention, cyanuric chloride can be mixed with ice water, stirred for 5-10 minutes to form a slurry, and then the slurry is mixed with p-aminobenzenesulfonic acid to perform the first reaction. As an embodiment of the present invention, the temperature of the first reaction can be 0-5°C, specifically 0°C, 1°C, 2°C, 3°C, 4°C or 5°C; the time can be 1-2h, specifically 1.5h.

[0021] After the first reaction, the present invention does not need to perform any post-treatment, and the pH value of the obtained first product solution is directly adjusted to 8~9, and then mixed with a soluble zinc salt solution and ethylenediamine to perform a second reaction to obtain a second product solution. As one embodiment of the present invention, the pH value reagent used to adjust the pH value of the first product solution is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution can be 0.1~1 mol / L, specifically 0.5 mol / L; in the embodiment of the present invention, the pH value of the first product solution can be specifically adjusted to 8.5. As one embodiment of the present invention, the soluble zinc salt in the soluble zinc salt solution can include zinc nitrate, zinc chloride or zinc sulfate, specifically zinc nitrate. In the embodiment of the present invention, zinc nitrate hexahydrate (Zn(NO) 3 6H 2 O); the concentration of the soluble zinc salt solution can be 2-20wt%, specifically 4wt%, 8wt%, 10wt% or 15wt%; the mass ratio of cyanuric chloride, soluble zinc salt and ethylenediamine can be 50:8-12:45-55, specifically 50:10:50. As one embodiment of the present invention, the pH value of the first product solution is adjusted to 8-9 and then heated to 45-55°C (specifically 50°C), the soluble zinc salt solution is added and stirred for 5-15min (specifically 10min), and then ethylenediamine is added dropwise to carry out the second reaction. As one embodiment of the present invention, the temperature of the second reaction can be 45-55°C, specifically 50°C; the time of the second reaction can be 1.5-2.5h, specifically 2h, and the time of the second reaction is counted from the completion of the addition of ethylenediamine.

[0022] After the second reaction, the present invention does not need to perform any post-treatment, and directly adjusts the pH value of the obtained second product liquid to 8~9 to obtain a precursor material. As an embodiment of the present invention, the pH value reagent used to adjust the pH value of the second product liquid is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution can be 0.1~1mol / L, specifically 0.5mol / L; in the embodiment of the present invention, the pH value of the second product liquid can be specifically adjusted to 8.5. As an embodiment of the present invention, after adjusting the pH value of the second product liquid to 8~9, the present invention stirs the obtained system for 10~20min to obtain a white viscous liquid, which is the precursor material, and the precursor material includes a triazine ultraviolet absorber and nano zinc hydroxide loaded on the triazine ultraviolet absorber; the particle size of the nano zinc hydroxide is ≤500nm.

[0023] After obtaining the precursor material, the present invention mixes the precursor material with polyester, performs extrusion granulation under heating conditions, and decomposes the nano zinc hydroxide to form nano zinc oxide to obtain the composite anti-UV masterbatch. As an embodiment of the present invention, the polyester can specifically use polyester chips, and the polyester chips can specifically be PETG polyester chips; the mass ratio of the precursor material to the polyester can be 2.5~3.5:6.5~7.5, further can be 2.8~3.2:6.8~7.2, specifically can be 7:3. As an embodiment of the present invention, the temperature of the extrusion granulation can be 215~225℃, further can be 218~223℃, specifically can be 220℃; the extrusion granulation can be carried out under vacuum conditions, so as to timely extract the moisture and other small molecules generated during the extrusion granulation process. As an embodiment of the present invention, the extrusion granulation can be carried out in a side-feeding twin-screw extruder granulator with a vacuum pumping function; in the embodiment of the present invention, the extrusion granulator is specifically heated to 215-225°C and kept warm for 1.5-2.5h (specifically 2h), and then PETG polyester chips are added and the precursor material is added from the side feed for extrusion granulation, and the vacuum port is opened during the extrusion granulation process to ensure that the generated moisture and other small molecules are extracted in time to obtain the composite anti-UV masterbatch.

[0024] The composite anti-UV masterbatch provided by the present invention is compounded by nano zinc oxide (formed by decomposition of nano zinc hydroxide in a process of extrusion granulation under heating conditions) and a triazine ultraviolet absorber, thereby saving the expensive cost of directly modifying the triazine ultraviolet absorber (such as introducing a monomer that can absorb light in a wavelength band that the triazine ultraviolet absorber cannot absorb for grafting modification), and the processing is simple and convenient.

[0025] The present invention provides a composite anti-UV masterbatch prepared by the preparation method described in the above technical scheme, comprising a polyester matrix and an anti-UV composite dispersed in the polyester matrix, wherein the anti-UV composite comprises a triazine ultraviolet absorber and nano zinc oxide loaded on the triazine ultraviolet absorber.

[0026] The composite anti-UV masterbatch of the present invention includes a polyester matrix and an anti-UV compound dispersed in the polyester matrix; the polyester matrix of the present invention specifically refers to a matrix material of the composite anti-UV masterbatch using polyester; the anti-UV compound includes a triazine ultraviolet absorber and nano zinc oxide loaded on the triazine ultraviolet absorber, and the content of nano zinc oxide in the anti-UV compound can be 5-9wt%, specifically 5wt%, 6wt%, 7wt%, 8wt% or 9wt%; the particle size of the nano zinc oxide can be ≤500nm, for example, 200-500nm, specifically 200nm, 300nm, 400nm or 500nm. As an embodiment of the present invention, the content of the anti-UV compound in the composite anti-UV masterbatch can be 25-35wt%, specifically 25wt%, 30wt% or 35wt%.

[0027] The present invention provides an anti-UV transparent heat shrinkable film, comprising a first surface layer, a core layer and a second surface layer which are stacked in sequence; the first surface layer and the second surface layer comprise a polyester matrix and an anti-blocking agent dispersed in the resin matrix; the core layer comprises a polyester matrix and a composite anti-UV masterbatch dispersed in the polyester matrix, and the composite anti-UV masterbatch is the composite anti-UV masterbatch described in the above technical solution.

[0028] The UV-resistant transparent heat shrinkable film of the present invention is a full-band high-efficiency UV-resistant transparent PETG heat shrinkable film, which can effectively block ultraviolet light in the range of 280-410nm, as described in detail below.

[0029] As an embodiment of the present invention, the thickness of the UV resistant transparent heat shrinkable film may be 30-50 μm, specifically 30 μm, 32 μm, 35 μm, 38 μm, 40 μm, 42 μm, 45 μm, 48 μm or 50 μm; the thickness of the core layer is 80-90% of the thickness of the UV resistant transparent heat shrinkable film, specifically 80%, 82%, 85%, 88% or 90%; the thickness of the first surface layer and the second surface layer may be the same.

[0030] The first surface layer and the second surface layer of the present invention include a polyester matrix and an opening agent dispersed in the resin matrix. As an embodiment of the present invention, the opening agent in the first surface layer and the second surface layer can independently include nano silicon dioxide and / or acid amide, specifically nano silicon dioxide; the particle size of the nano silicon dioxide can be 0.6~1μm, specifically 0.6μm, 0.8μm or 1μm; the content of the opening agent in the first surface layer and the second surface layer can be 1~3wt% independently, specifically 1wt%, 1.3wt%, 1.5wt%, 1.8wt%, 2wt%, 2.3wt%, 2.5wt%, 2.8wt% or 3wt%. The above-mentioned type and amount of opening agent used in the embodiment of the present invention can achieve efficient separation between different layers, which is conducive to reducing the friction coefficient of the film.

[0031] The core layer of the present invention includes a polyester matrix and a composite anti-UV masterbatch dispersed in the polyester matrix. As an embodiment of the present invention, the content of the composite anti-UV masterbatch in the core layer can be 3-5wt%, specifically 3wt%, 3.3wt%, 3.5wt%, 3.8wt%, 4wt%, 4.3wt%, 4.5wt%, 4.8wt% or 5wt%. In the embodiment of the present invention, the amount of the composite anti-UV masterbatch is limited to the above range, which can effectively block full-band ultraviolet light and is conducive to the efficient preservation of the contents.

[0032] The present invention provides a method for preparing the UV-resistant transparent heat shrinkable film described in the above technical solution, comprising the following steps: According to the composition and ingredients of the first surface layer, the core layer and the second surface layer in the anti-UV transparent heat shrinkable film, the anti-UV transparent heat shrinkable film is obtained by sequentially undergoing melt plasticization, co-extrusion, cast film and stretching.

[0033] The present invention does not particularly limit the conditions for the melt plasticization, and conditions familiar to those skilled in the art can be used; the coextrusion is carried out in an extruder, and the processing temperature of the extruder can be 200-250°C, specifically 200°C, 210°C, 220°C, 230°C, 240°C or 250°C; the die head temperature of the extruder can be 220-260°C, specifically 220°C, 230°C, 240°C, 250°C or 260°C; the present invention does not particularly limit the conditions for the cast sheet, and conditions familiar to those skilled in the art can be used.

[0034] As an embodiment of the present invention, the stretching includes sequentially performing longitudinal stretching and transverse stretching. As an embodiment of the present invention, the longitudinal stretching includes sequentially performing first preheating, first stretching and first shaping, and the conditions of the longitudinal stretching include: the first preheating temperature can be 120~170℃, specifically 120℃, 130℃, 140℃, 150℃, 160℃ or 170℃; the first stretching temperature can be 80~120℃, specifically 80℃, 90℃, 100℃, 110℃ or 120℃; the first shaping temperature can be 50~90℃, specifically 50℃, 60℃, 70℃, 80℃ or 90℃. As an embodiment of the present invention, the transverse stretching includes sequentially performing a second preheating, a second stretching and a second setting, and the conditions of the transverse stretching include: the second preheating temperature can be 100~150℃, specifically 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃; the second stretching temperature can be 80~120℃, specifically 80℃, 90℃, 100℃, 110℃ or 120℃; the second setting temperature can be 50~90℃, specifically 50℃, 60℃, 70℃, 80℃ or 90℃.

[0035] The present invention provides the use of the UV-resistant transparent heat shrinkable film described in the above technical solution or the UV-resistant transparent heat shrinkable film prepared by the preparation method described in the above technical solution in a label. As an embodiment of the present invention, the UV-resistant transparent heat shrinkable film can be used as a label wrapped around the outside of a transparent PET bottle. On this basis, when the transparent PET bottle is used to hold dairy products or medicines, the dairy products and medicines can be prevented from being degraded by ultraviolet light.

[0036] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1 Weigh 10 parts by mass of zinc nitrate hexahydrate (Zn(NO) 3 6H 2 O) was dissolved in 100 parts of distilled water and stirred magnetically for 10 min to obtain a zinc nitrate solution; Based on the mass fraction of the zinc nitrate hexahydrate, 50 parts of cyanuric chloride are added to 400 parts of ice water (temperature is 0°C), stirred for 5 minutes to obtain a slurry, and then 48 parts of p-aminobenzenesulfonic acid are added and reacted at 0°C for 1.5 hours; after the reaction is completed, a 0.5 mol / L sodium hydroxide solution is used to adjust the pH value to 8.5, and then the temperature is raised to 50°C, and the obtained material is added to the zinc nitrate solution, stirred at 50°C for 10 minutes, 50 parts of ethylenediamine are added to the obtained mixed liquid, and the reaction is carried out at 50°C for 2 hours. After the reaction is completed, a 0.5 mol / L sodium hydroxide solution is used to adjust the pH value to 8.5, and then stirred for 15 minutes to obtain a white viscous liquid, which is a precursor material (the precursor material includes a triazine ultraviolet absorber and nano zinc hydroxide supported on the triazine ultraviolet absorber, and the particle size of the nano zinc hydroxide is ≤500nm); The side-feeding twin-screw extruder granulator with a vacuum function is heated to 220° C. and kept warm for 2 hours, then PETG polyester chips are added to the extruder granulator, the precursor material is added from the side feed, and the mass ratio of the precursor material to the PETG polyester chips is 3:7, and extrusion granulation is performed under vacuum conditions to ensure that the generated moisture and other small molecules are extracted in time to obtain a composite anti-UV masterbatch (i.e., a masterbatch with PETG as a matrix and containing 30wt% of an anti-UV compound, wherein the anti-UV compound includes a triazine ultraviolet absorber and nano zinc oxide loaded on the triazine ultraviolet absorber).

[0038] Example 2 PETG polyester chips and nano silicon dioxide (average particle size of 0.8 μm) were mixed at a mass ratio of 98:2 to obtain a surface layer mixed raw material; The PETG polyester chips and the composite anti-UV masterbatch prepared in Example 1 were mixed at a mass ratio of 95:5 to obtain a core layer mixed raw material; According to the structure of the first surface layer, the core layer and the second surface layer stacked in sequence, the surface layer mixed raw material and the core layer mixed raw material are sequentially melt-plasticized, co-extruded and cast in an extruder to obtain a cast sheet material; wherein the processing temperature of the extruder used for co-extrusion is 240° C., and the die head temperature is 240° C.; The cast sheet material is sequentially subjected to longitudinal stretching and transverse stretching to obtain a UV-resistant transparent heat shrinkable film; wherein, the preheating temperature during the longitudinal stretching is 100°C, the stretching temperature is 85°C, the setting temperature is 50°C, and the longitudinal stretching multiple is 1.2 times; the preheating temperature during the transverse stretching is 120°C, the stretching temperature is 90°C, the setting temperature is 60°C, and the transverse stretching multiple is 4.8 times; the UV-resistant transparent heat shrinkable film specifically includes a first surface layer, a core layer and a second surface layer which are sequentially stacked, the first surface layer and the second surface layer have the same composition and thickness, the total thickness of the UV-resistant transparent heat shrinkable film is 40 μm, and the thickness of the core layer is 85% of the thickness of the UV-resistant transparent heat shrinkable film.

[0039] Example 3 The method of Example 2 was followed, except that the mass ratio of PETG polyester chips to composite anti-UV masterbatch in the core layer mixed raw material was 97:3.

[0040] Example 4 The method of Example 2 was followed, except that the total thickness of the UV-resistant transparent heat shrinkable film was 50 μm.

[0041] Comparative Example 1 The operation is carried out in accordance with Example 2, except that the precursor material is replaced with nano zinc oxide. The specific steps are as follows: The side-feeding twin-screw extruder granulator with a vacuum function is heated to 220° C. and kept warm for 2 hours, and then PETG polyester chips are added to the extruder granulator, and nano zinc oxide is added from the side feed, and the mass ratio of the nano zinc oxide to the PETG polyester chips is 3:7, and extrusion granulation is performed under vacuum conditions to ensure that the generated water and other small molecules are extracted in time, to obtain a composite anti-UV masterbatch (i.e., a masterbatch with PETG as the matrix and containing 30wt% of nano zinc oxide); Then, the UV-resistant transparent heat shrinkable film was prepared according to the method of Example 2.

[0042] Comparative Example 2 The operation is carried out in accordance with Example 2, except that the precursor material is replaced with a triazine ultraviolet absorber. The specific steps are as follows: 50 parts of cyanuric chloride were added to 400 parts of ice water (temperature was 0°C), stirred for 5 minutes to obtain a slurry, then 48 parts of p-aminobenzenesulfonic acid were added and reacted at 0°C for 1.5 hours; after the reaction was completed, a 0.5 mol / L sodium hydroxide solution was used to adjust the pH value to 8.5, then the temperature was raised to 50°C, 50 parts of ethylenediamine were added to the obtained mixed liquid, and the mixture was reacted at 50°C for 2 hours, and after the reaction was completed, a 0.5 mol / L sodium hydroxide solution was used to adjust the pH value to 8.5, and then stirred for 15 minutes to obtain a white viscous liquid, which was a triazine ultraviolet absorber; The side-feeding twin-screw extruder granulator with a vacuum function is heated to 220° C. and kept warm for 2 hours, then PETG polyester chips are added to the extruder granulator, and the triazine ultraviolet absorber is added from the side feed, and the mass ratio of the triazine ultraviolet absorber to the PETG polyester chips is 3:7, and granulation is performed under vacuum conditions to ensure that the generated moisture and other small molecular substances are extracted in time to obtain a composite anti-UV masterbatch (i.e., a masterbatch with PETG as the matrix and containing 30wt% of the triazine ultraviolet absorber); Then, the UV-resistant transparent heat shrinkable film was prepared according to the method of Example 2.

[0043] Comparative Example 3 The operation was carried out in accordance with Example 2, except that the composite anti-UV masterbatch was omitted from the core layer mixed raw material, that is, only PETG polyester chips were used as the core layer raw material.

[0044] Test Example 1 The UV-resistant transparent heat shrinkable films prepared in the examples and comparative examples were tested for their UV resistance, wherein the light transmittance test was conducted in accordance with ASTM D 1003, and the haze test was conducted in accordance with ASTM D 1003. Figure 1 The figures are UV light transmittance diagrams of the UV-resistant transparent heat shrinkable films prepared in various embodiments and comparative examples in different bands. Table 1 is the light transmittance test results of the UV-resistant transparent heat shrinkable films prepared in various embodiments and comparative examples under light with a wavelength of 550nm. It can be seen that the UV-resistant transparent heat shrinkable films prepared by using the composite UV-resistant masterbatch in Examples 2 to 4 of the present invention have excellent UV resistance; the nano zinc oxide used in Comparative Example 1 is easy to agglomerate, resulting in the inability to effectively block the ultraviolet light, so the light transmittance is relatively low and the haze is relatively high; the triazine ultraviolet absorber used in Comparative Example 2 can only absorb ultraviolet light in a lower band (280-380nm) due to its own characteristics, and has a poor absorption effect on ultraviolet light above a wavelength of 380nm; the composite UV-resistant masterbatch is not used in Comparative Example 3 (that is, neither nano zinc oxide nor triazine ultraviolet absorber is used), and there is no blocking effect on UV light.

[0045] Table 1 Test results of light transmittance of the UV-resistant transparent heat shrinkable films prepared in various embodiments and comparative examples under 550nm wavelength light

[0046] Test Example 2 The UV-resistant transparent heat shrinkable films prepared in each embodiment and comparative example were subjected to mechanical property tests, wherein the strength test method used was ASTMD 882, the modulus test method used was ASTMD 882, and the elongation at break test method used was ASTM D 882. Table 2 shows the mechanical property test results of the UV-resistant transparent heat shrinkable films prepared in each embodiment and comparative example. It can be seen that, except for Example 4, there is no significant difference in the mechanical properties of the UV-resistant transparent heat shrinkable films prepared in the other embodiments and comparative examples. This indicates that the addition of the composite anti-UV masterbatch does not affect the mechanical properties of the film, and the mechanical properties are related to the film thickness.

[0047] Table 2 Mechanical properties test results of the UV-resistant transparent heat shrinkable films prepared in various embodiments and comparative examples

[0048] In summary, the full-band high-efficiency UV-resistant transparent heat shrinkable film prepared by the present invention has good transparency, a wide range of UV blocking bands, and excellent mechanical properties, and can effectively replace milky white packaging films or bottles, perfectly meeting the use scenarios of labels.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a composite anti-UV masterbatch, comprising the following steps: Mixing cyanuric chloride, p-aminobenzenesulfonic acid and water to carry out a first reaction to obtain a first product liquid; The first product solution is adjusted to a pH value of 8 to 9, and then mixed with a soluble zinc salt solution and ethylenediamine to perform a second reaction, and then the pH value of the obtained second product solution is adjusted to 8 to 9 to obtain a precursor material, wherein the precursor material includes a triazine ultraviolet absorber and nano zinc hydroxide supported on the triazine ultraviolet absorber; The precursor material is mixed with polyester, extruded and granulated under heating conditions, and the nano zinc hydroxide is decomposed to form nano zinc oxide, so as to obtain the composite anti-UV masterbatch.

2. The preparation method according to claim 1, characterized in that: The mass ratio of cyanuric chloride to p-aminobenzenesulfonic acid is 50:45-51; the temperature of the first reaction is 0-5°C and the time is 1-2h; The soluble zinc salt in the soluble zinc salt solution includes zinc nitrate, zinc chloride or zinc sulfate, the mass ratio of cyanuric chloride, soluble zinc salt and ethylenediamine is 50:8-12:45-55; the temperature of the second reaction is 45-55°C, and the time is 1.5-2.5h.

3. The preparation method according to claim 1 or 2, characterized in that: The temperature of the extrusion granulation is 215-225°C.

4. The composite anti-UV masterbatch prepared by the preparation method according to any one of claims 1 to 3 comprises a polyester matrix and an anti-UV composite dispersed in the polyester matrix, wherein the anti-UV composite comprises a triazine ultraviolet absorber and nano zinc oxide supported on the triazine ultraviolet absorber.

5. The composite anti-UV masterbatch according to claim 4, characterized in that: The content of the anti-UV compound in the composite anti-UV masterbatch is 25-35wt%.

6. A UV-resistant transparent heat shrinkable film, comprising a first surface layer, a core layer and a second surface layer stacked in sequence; the first surface layer and the second surface layer comprise a polyester matrix and an opening agent dispersed in the resin matrix; the core layer comprises a polyester matrix and a composite UV-resistant masterbatch dispersed in the polyester matrix, and the composite UV-resistant masterbatch is the composite UV-resistant masterbatch according to claim 4 or 5.

7. The UV-resistant transparent heat shrinkable film according to claim 6, characterized in that: The thickness of the anti-UV transparent heat shrinkable film is 30-50 μm, and the thickness of the core layer is 80-90% of the thickness of the anti-UV transparent heat shrinkable film.

8. The UV-resistant transparent heat shrinkable film according to claim 6 or 7, characterized in that: The opening agent in the first surface layer and the second surface layer independently comprises nano silicon dioxide and / or acid amide, the content of the opening agent in the first surface layer and the second surface layer independently is 1-3wt%, and the content of the composite anti-UV masterbatch in the core layer is 3-5wt%.

9. The method for preparing the UV-resistant transparent heat shrinkable film according to any one of claims 6 to 8, comprising the following steps: According to the composition and ingredients of the first surface layer, the core layer and the second surface layer in the anti-UV transparent heat shrinkable film, the anti-UV transparent heat shrinkable film is obtained by sequentially undergoing melt plasticization, co-extrusion, cast film and stretching.

10. Use of the UV-resistant transparent heat shrinkable film according to any one of claims 6 to 8 or the UV-resistant transparent heat shrinkable film prepared by the preparation method according to claim 9 in labels.

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