A double-sided heat-seal BOPP matt film and a preparation method thereof

Abstract

The present application relates to the technical field of extinction film, in particular to a double-sided heat-seal BOPP extinction film and a preparation method thereof, which comprises extinction heat-seal layer, support layer and corona heat-seal layer arranged in sequence; the thickness of the BOPP extinction film is 10-50 microns, and the thickness ratio of the extinction heat-seal layer, the support layer and the corona heat-seal layer is (1-4):(2-8):(1-4). The production method provided by the present application is produced through three-layer co-extrusion casting process and two-way stretching process, which is simple to manufacture, low in cost, rich in raw material sources and environment-friendly.

Description

Technical Field

[0001] This invention relates to the field of matte film technology, specifically to a double-sided heat-sealable BOPP matte film and its preparation method. Background Technology

[0002] BOPP matte film is a plastic product with low gloss and high haze diffuse reflection, giving it a paper-like appearance. It allows for realistic color reproduction during printing and provides a comfortable feel. It is widely used in various packaging fields, including food, pharmaceuticals, cosmetics, and electronic products. For example, when laminated with packaging paper or cardboard boxes, matte film can significantly enhance the quality of the packaging and is widely used in soap, tobacco, alcohol, clothing, footwear, perfumes, cosmetics, and pharmaceuticals.

[0003] BOPP matte film is mainly prepared by multi-layer co-extrusion casting and biaxial stretching processes using resin blending or the addition of inorganic matting agents (masterbatch). Regarding resin blending modification, during production, two issues arise: firstly, poor resin compatibility leads to weak interfaces on the cast film surface. During biaxial stretching, uneven longitudinal and transverse tension causes these weak interfaces to easily open or break, resulting in numerous bright spots on the film surface. Secondly, the different crystallization behaviors of different resins lead to uneven spherulite size during biaxial stretching, easily forming large spherulites, resulting in a rough matte surface and white spots. Regarding the addition of inorganic matting agents (masterbatch), poor compatibility between the inorganic matting agent (masterbatch) and the resin easily creates weak interfaces. During biaxial stretching, these weak interfaces are easily opened, causing numerous bright spots. Furthermore, the uneven particle size of the inorganic matting agent easily generates white spots in the film. In addition, currently, BOPP matte films are primarily single-sided heat-sealed, while double-sided heat-sealed BOPP matte film technology has not been reported.

[0004] Currently, there is no technological breakthrough addressing the aforementioned issues. Therefore, how to provide a new technology to prepare a white-point-free, bright, double-sided heat-sealed BOPP matte film is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the purpose of this invention is to provide a double-sided heat-sealable BOPP matte film and its preparation method, so as to solve the problems mentioned in the background art.

[0006] The present invention solves the technical problem by adopting the following technical solution:

[0007] The present invention provides a double-sided heat-sealable BOPP matte film, comprising a matte heat-sealing layer, a support layer and a corona heat-sealing layer arranged sequentially; the thickness of the BOPP matte film is 10μm to 50μm, and the thickness ratio of the matte heat-sealing layer, the support layer and the corona heat-sealing layer is (1-4):(2-8):(1-4).

[0008] Preferably, the matte heat-sealing layer comprises, by weight percentage, 20%–50% ternary random copolymer polypropylene, 0%–30% binary random copolymer polypropylene, 30%–70% high-density polyethylene, 1%–5% opening slip agent, 0%–0.2% nucleating agent, and 1%–10% compatibilizer.

[0009] The support layer, by weight percentage, comprises 70%–100% homopolymer polypropylene, 0%–30% block copolymer polypropylene, 0%–0.2% nucleating agent, and 1%–10% compatibilizer;

[0010] The corona heat seal layer comprises, by weight percentage, 0%–100% ternary random copolymer polypropylene, 0%–50% binary random copolymer polypropylene, 0%–0.2% nucleating agent, and 1%–10% compatibilizer.

[0011] Preferably, the opening slip agent is silica with a particle size of 0.5 μm to 4 μm;

[0012] The nucleating agent is one or more of the following: aryl amide nucleating agents, sorbitol nucleating agents, branched acid amine transparent nucleating agents, aryl phosphate transparent nucleating agents, carboxylic acid metal salt transparent nucleating agents, dehydropolar acids and their salts nucleating agents;

[0013] The compatibilizer is one or more of the following: maleic anhydride graft compatibilizer, cyclic anhydride compatibilizer, carboxylic acid compatibilizer, oxazoline compatibilizer, imide compatibilizer, ethylene propylene rubber, POE, EVA, and isocyanate compatibilizer.

[0014] Preferably, the high-density polyethylene has a melting point of 125℃~135℃ and a melt index of 5~15g / 10min (190℃, 21.6kg), with a melt index preferably of 6~10g / 10min;

[0015] The ternary random copolymer polypropylene has a melting point of 125℃~135℃ and a melt index of 2~9g / 10min (230℃, 2.16kg), with a preferred melt index of 3~7g / 10min.

[0016] The binary random copolymer polypropylene has a melting point of 135℃~150℃ and a melt index of 4~18g / 10min (230℃, 2.16kg), with a preferred melt index of 6~16g / 10min.

[0017] The homopolymer polypropylene has a melting point ≥160℃ and a melt index of 2-8 g / 10 min, preferably 3-5 g / 10 min.

[0018] The selected block polypropylene has a melting point ≥163℃ and a melt index of 1~8g / 10min, preferably 2~5g / 10min.

[0019] Preferably, the support layer further contains 7% to 10% of a balancing agent and 3% to 5% of a modified filler.

[0020] The preparation method of the balancing agent is as follows:

[0021] S01: Add 4-7 parts of carboxymethyl cellulose and 1-3 parts of nano-silica sol to 5-8 parts of cerium nitrate solution, then add 2-3 parts of silane coupling agent, stir evenly to obtain modified carboxymethyl cellulose solution;

[0022] SO2: Nano-titanium oxide is preheated at 55-60℃ for 1 hour to obtain preheated nano-titanium oxide;

[0023] The preheated nano-titanium dioxide and modified carboxymethyl cellulose solution were stirred at a weight ratio of 3:5. After stirring, a carboxymethyl cellulose-nano-titanium dioxide blended solution was obtained.

[0024] S03: The mixture of zinc oxide whiskers / sodium alginate and carboxymethyl cellulose-nano titanium dioxide compound solution was ball-milled at a weight ratio of 5:(2~3) for 1 hour at a speed of 1500 r / min. After the ball milling was completed, the mixture was filtered and dried to obtain the compounding agent.

[0025] Preferably, the cerium nitrate solution has a mass fraction of 5-8%; the silane coupling agent is silane coupling agent KH550; the stirring speed is 350-400 r / min, and the stirring time is 1 h.

[0026] Preferably, the preparation method of the mixed zinc oxide whiskers / sodium alginate formulation is as follows:

[0027] Add 5-8 parts of zinc oxide whiskers and 2-4 parts of sodium alginate powder to 4-7 parts of 5% yttrium nitrate solution, then add 2-3 parts of boron oxide and 0.4-0.5 parts of glass fiber, stir evenly, filter and dry to obtain a mixture of zinc oxide whiskers and sodium alginate.

[0028] Preferably, the modified filler is prepared by:

[0029] S11: Dissolve tetrabutyl titanate in anhydrous ethanol at a weight ratio of 2:(7-9), then add 10-15% of the total amount of tetrabutyl titanate silane coupling agent KH560 and 2-5% of the total amount of tetrabutyl titanate nano silica sol, stir evenly to obtain modified tetrabutyl titanate solution.

[0030] S12: Place the nano-attapulgite in a sodium silicate solution with a mass fraction of 5% (3-5 times the total amount of nano-attapulgite), and then add a urea solution with a mass fraction of 4% (10-15% of the total amount of nano-attapulgite). Ball mill the nano-attapulgite for 2 hours at a speed of 1000 r / min. After the ball milling is completed, the pretreated nano-attapulgite is obtained.

[0031] S13: The pretreated nano-attapulgite and modified tetrabutyl titanate solution are ultrasonically modified at a weight ratio of 5:7, with a modification power of 350-370W, for 1 hour. After modification, the mixture is filtered and dried to obtain the modified filler.

[0032] This invention also provides a method for preparing a double-sided heat-sealable BOPP matte film, comprising the following steps:

[0033] (1) Weigh the raw materials for the photothermal sealing layer, support layer and corona heat sealing layer by weight percentage;

[0034] (2) The raw materials of the matte heat-sealing layer, the support layer and the corona heat-sealing layer are respectively fed into the A, B and C extruders of the three-layer co-extrusion casting machine. After adjusting the equipment according to the layer thickness ratio and the extruder processing temperature, the machine is started. Thin sheets are prepared by co-extrusion casting process, and then bi-directional stretching is carried out by bi-stretching process to obtain BOPP matte film.

[0035] Preferably, in step (2), the extrusion temperature of extruders A and B is 240℃, and the extrusion temperature of extruder C is 230℃; longitudinal stretching: preheating temperature 115-120℃, stretching ratio 5:1; transverse stretching: preheating zone 125-130℃, stretching ratio 10:1, setting temperature 155℃.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The double-sided heat-sealable BOPP matte film prepared by this invention is produced by a three-layer co-extrusion → biaxial stretching process. It consists of a first matte heat-sealable layer (inner layer), a second support layer (core layer), and a third corona-treated heat-sealable layer (surface layer). By adjusting the proportion of each layer, the double-sided heat-sealable BOPP matte film without white spots or bright spots is prepared. It is detected by a high-resolution CCD camera (detection accuracy 50μm) and shows no white spots or bright spots. After heat sealing and cooling, it exhibits good double-sided heat-sealing performance and shows broad application prospects in high-end rapid packaging, lamination, printing and other fields.

[0038] In the preparation of BOPP matte film, a balancing agent and a modified filler are added to the support layer. Through the synergistic effect between these two raw materials, the product's haze, elongation at break, and transmittance are optimized while ensuring the absence of white spots and bright spots. The balancing agent is prepared by ball milling a mixture of zinc oxide whiskers / sodium alginate and a carboxymethyl cellulose-nano titanium dioxide blending solution. The zinc oxide whisker / sodium alginate blending agent uses zinc oxide whiskers as the matrix, supplemented by boron oxide and glass fiber. Sodium alginate powder and yttrium nitrate solution are also added. Through the synergistic blending of raw materials, whisker-shaped zinc oxide whiskers and needle-shaped glass fibers are combined with boron oxide and other raw materials. This enhances the interfacial properties between raw materials and their integration into the system, supporting the system structure and improving the system's performance coordination and stability. The carboxymethyl cellulose-nano titanium dioxide blended solution is made by stirring preheated nano titanium dioxide and modified carboxymethyl cellulose solution. The carboxymethyl cellulose, nano silica sol, cerium nitrate solution, and silane coupling agent in the modified carboxymethyl cellulose solution are blended and coordinated with each other. Combined with improved nano titanium dioxide, the co-mixing optimization between raw materials results in a better coordination effect between the carboxymethyl cellulose-nano titanium dioxide blended solution and the mixed zinc oxide whiskers / sodium alginate balancing agent. Therefore, when blended into the product system, the performance coordination effect is better.

[0039] The modified filler is made by blending and optimizing nano-attapulgite clay with sodium silicate solution, and then further improved by ball milling with urea solution. At the same time, tetrabutyl titanate is blended and improved by anhydrous ethanol, silane coupling agent KH560 and nano-silica sol. The resulting modified tetrabutyl titanate solution further coordinates with the pretreated nano-attapulgite in the system, resulting in a stronger synergistic effect between the modified filler and the coupling agent, and further improving the performance of the product. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the production process of the double-sided heat-sealed BOPP matte film of the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] This embodiment of a double-sided heat-sealable BOPP matte film includes a matte heat-sealing layer, a support layer, and a corona heat-sealing layer arranged sequentially; the thickness of the BOPP matte film is 10μm to 50μm, and the thickness ratio of the matte heat-sealing layer, the support layer, and the corona heat-sealing layer is (1-4):(2-8):(1-4).

[0044] The matte heat-sealing layer of this embodiment comprises, by weight percentage, 20%–50% ternary random copolymer polypropylene, 0%–30% binary random copolymer polypropylene, 30%–70% high-density polyethylene, 1%–5% opening slip agent, 0%–0.2% nucleating agent, and 1%–10% compatibilizer;

[0045] The support layer, by weight percentage, comprises 70%–100% homopolymer polypropylene, 0%–30% block copolymer polypropylene, 0%–0.2% nucleating agent, and 1%–10% compatibilizer;

[0046] The corona heat seal layer comprises, by weight percentage, 0%–100% ternary random copolymer polypropylene, 0%–50% binary random copolymer polypropylene, 0%–0.2% nucleating agent, and 1%–10% compatibilizer.

[0047] The opening slip agent in this embodiment is silica with a particle size of 0.5μm to 4μm;

[0048] The nucleating agent is one or more of the following: aryl amide nucleating agents, sorbitol nucleating agents, branched acid amine transparent nucleating agents, aryl phosphate transparent nucleating agents, carboxylic acid metal salt transparent nucleating agents, dehydropolar acids and their salts nucleating agents;

[0049] The compatibilizer is one or more of the following: maleic anhydride graft compatibilizer, cyclic anhydride compatibilizer, carboxylic acid compatibilizer, oxazoline compatibilizer, imide compatibilizer, ethylene propylene rubber, POE, EVA, and isocyanate compatibilizer.

[0050] The high-density polyethylene in this embodiment has a melting point of 125℃~135℃ and a melt index of 5~15g / 10min (190℃, 21.6kg), with a preferred melt index of 6~10g / 10min;

[0051] The ternary random copolymer polypropylene has a melting point of 125℃~135℃ and a melt index of 2~9g / 10min (230℃, 2.16kg), with a preferred melt index of 3~7g / 10min.

[0052] The binary random copolymer polypropylene has a melting point of 135℃~150℃ and a melt index of 4~18g / 10min (230℃, 2.16kg), with a preferred melt index of 6~16g / 10min.

[0053] The homopolymer polypropylene has a melting point ≥160℃ and a melt index of 2-8 g / 10 min, preferably 3-5 g / 10 min.

[0054] The selected block polypropylene has a melting point ≥163℃ and a melt index of 1~8g / 10min, preferably 2~5g / 10min.

[0055] The support layer in this embodiment also contains 7% to 10% of a balancing agent and 3% to 5% of a modified filler.

[0056] The preparation method of the balancing agent is as follows:

[0057] S01: Add 4-7 parts of carboxymethyl cellulose and 1-3 parts of nano-silica sol to 5-8 parts of cerium nitrate solution, then add 2-3 parts of silane coupling agent, stir evenly to obtain modified carboxymethyl cellulose solution;

[0058] SO2: Nano-titanium oxide is preheated at 55-60℃ for 1 hour to obtain preheated nano-titanium oxide;

[0059] The preheated nano-titanium dioxide and modified carboxymethyl cellulose solution were stirred at a weight ratio of 3:5. After stirring, a carboxymethyl cellulose-nano-titanium dioxide blended solution was obtained.

[0060] S03: The mixture of zinc oxide whiskers / sodium alginate and carboxymethyl cellulose-nano titanium dioxide compound solution was ball-milled at a weight ratio of 5:(2~3) for 1 hour at a speed of 1500 r / min. After the ball milling was completed, the mixture was filtered and dried to obtain the compounding agent.

[0061] In this embodiment, the cerium nitrate solution has a mass fraction of 5-8%; the silane coupling agent is silane coupling agent KH550; the stirring speed is 350-400 r / min, and the stirring time is 1 h.

[0062] The preparation method of the hybrid zinc oxide whisker / sodium alginate formulation in this embodiment is as follows:

[0063] Add 5-8 parts of zinc oxide whiskers and 2-4 parts of sodium alginate powder to 4-7 parts of 5% yttrium nitrate solution, then add 2-3 parts of boron oxide and 0.4-0.5 parts of glass fiber, stir evenly, filter and dry to obtain a mixture of zinc oxide whiskers and sodium alginate.

[0064] The preparation method of the modified filler in this embodiment is as follows:

[0065] S11: Dissolve tetrabutyl titanate in anhydrous ethanol at a weight ratio of 2:(7-9), then add 10-15% of the total amount of tetrabutyl titanate silane coupling agent KH560 and 2-5% of the total amount of tetrabutyl titanate nano silica sol, stir evenly to obtain modified tetrabutyl titanate solution.

[0066] S12: Place the nano-attapulgite in a sodium silicate solution with a mass fraction of 5% (3-5 times the total amount of nano-attapulgite), and then add a urea solution with a mass fraction of 4% (10-15% of the total amount of nano-attapulgite). Ball mill the nano-attapulgite for 2 hours at a speed of 1000 r / min. After the ball milling is completed, the pretreated nano-attapulgite is obtained.

[0067] S13: The pretreated nano-attapulgite and modified tetrabutyl titanate solution are ultrasonically modified at a weight ratio of 5:7, with a modification power of 350-370W, for 1 hour. After modification, the mixture is filtered and dried to obtain the modified filler.

[0068] This embodiment describes a method for preparing a double-sided heat-sealable BOPP matte film, comprising the following steps:

[0069] (1) Weigh the raw materials for the photothermal sealing layer, support layer and corona heat sealing layer by weight percentage;

[0070] (2) The raw materials of the matte heat-sealing layer, the support layer and the corona heat-sealing layer are respectively fed into the A, B and C extruders of the three-layer co-extrusion casting machine. After adjusting the equipment according to the layer thickness ratio and the extruder processing temperature, the machine is started. Thin sheets are prepared by co-extrusion casting process, and then bi-directional stretching is carried out by bi-stretching process to obtain BOPP matte film.

[0071] In step (2) of this embodiment, the extrusion temperature of extruders A and B is 240℃, and the extrusion temperature of extruder C is 230℃; longitudinal stretching: preheating temperature 115-120℃, stretching ratio 5:1; transverse stretching: preheating zone 125-130℃, stretching ratio 10:1, setting temperature 155℃.

[0072] Example 1

[0073] By weight percentage, a matte heat-sealing layer was prepared using 30% ternary random copolymer polypropylene, 20% binary random copolymer polypropylene, 40% high-density polyethylene, 2% opening slip agent, 0.05% nucleating agent, and 7.95% compatibilizer. The ternary random copolymer polypropylene (Maoming Petrochemical F8005) had a melting point of 131℃ and a melt index of 5.6 g / 10 min; the binary random copolymer polypropylene (Shanghai Petrochemical F800E) had a melting point of 143℃ and a melt index of 7.5 g / 10 min; the high-density polyethylene (ExxonMobil 001) had a melting point of 125℃ and a melt index of 8.6 g / 10 min; the nucleating agent (Japan Adico NA-21); and the compatibilizer (Guangdong Lushan AP302) had a melting point of 146.5℃ and a melt index of 7.0 g / 10 min.

[0074] A support layer was prepared using 70% homopolymer polypropylene, 15% block copolymer polypropylene, and 5% compatibilizer. The homopolymer polypropylene (Sichuan Petrochemical L5E89) had a melting point of 166℃ and a melt index of 3.1 g / 10 min; the block copolymer polypropylene (Maoming Petrochemical HR2106M) had a melting point of 165℃ and a melt index of 5.2 g / 10 min; and the compatibilizer (Guangdong Lushan AP302) had a melting point of 146.5℃ and a melt index of 7.0 g / 10 min.

[0075] The support layer also contains 7% balancing agent and 3% modified filler.

[0076] The preparation method of the balancing agent is as follows:

[0077] S01: Add 4 parts of carboxymethyl cellulose and 1 part of nano silica sol to 5 parts of cerium nitrate solution, then add 2 parts of silane coupling agent, stir evenly to obtain modified carboxymethyl cellulose solution;

[0078] S02: Nano-titanium oxide is preheated at 55℃ for 1 hour to obtain preheated nano-titanium oxide;

[0079] The preheated nano-titanium dioxide and modified carboxymethyl cellulose solution were stirred at a weight ratio of 3:5. After stirring, a carboxymethyl cellulose-nano-titanium dioxide blended solution was obtained.

[0080] S03: The mixture of zinc oxide whiskers / sodium alginate and carboxymethyl cellulose-nano titanium dioxide compound solution was ball-milled at a weight ratio of 5:2 for 1 hour at a speed of 1500 r / min. After ball milling, the mixture was filtered and dried to obtain the compounding agent.

[0081] In this embodiment, the cerium nitrate solution has a mass fraction of 5%; the silane coupling agent is silane coupling agent KH550; the stirring speed is 350 r / min, and the stirring time is 1 h.

[0082] The preparation method of the hybrid zinc oxide whisker / sodium alginate formulation in this embodiment is as follows:

[0083] Five parts of zinc oxide whiskers and two parts of sodium alginate powder were added to four parts of 5% yttrium nitrate solution. Then, two parts of boron oxide and 0.4 parts of glass fiber were added, stirred evenly, filtered and dried to obtain a mixture of zinc oxide whiskers and sodium alginate.

[0084] The preparation method of the modified filler in this embodiment is as follows:

[0085] S11: Dissolve tetrabutyl titanate in anhydrous ethanol at a weight ratio of 2:7, then add 10% of the total amount of tetrabutyl titanate silane coupling agent KH560 and 2% of the total amount of tetrabutyl titanate nano silica sol, stir evenly to obtain modified tetrabutyl titanate solution.

[0086] S12: Place the nano-attapulgite in a sodium silicate solution with a mass fraction of 5% (3 times the total amount of nano-attapulgite), and then add a urea solution with a mass fraction of 4% (10% of the total amount of nano-attapulgite). Ball mill the mixture for 2 hours at a speed of 1000 r / min. After the ball milling is completed, the pretreated nano-attapulgite is obtained.

[0087] S13: The pretreated nano-attapulgite and modified tetrabutyl titanate solution were ultrasonically modified at a weight ratio of 5:7. The modification power was 350W, and the modification was carried out for 1 hour. After the modification was completed, the mixture was filtered and dried to obtain the modified filler.

[0088] A corona heat seal layer was prepared using 80% ternary random copolymer polypropylene, 10% binary copolymer polypropylene, 9.95% compatibilizer, and 0.05% nucleating agent. Specifically, the ternary random copolymer polypropylene (Maoming Petrochemical F8005) had a melting point of 131℃ and a melt index of 5.6 g / 10 min; the binary random copolymer polypropylene (Maoming Petrochemical F08A) had a melting point of 145℃ and a melt index of 7.2 g / 10 min; the nucleating agent (Japan Adico NA-21) and the compatibilizer (Guangdong Lushan AP302) had melting points of 146.5℃ and melt index of 7.0 g / 10 min.

[0089] The above-mentioned heat-sealing layer, support layer and corona heat-sealing layer raw materials are blended according to weight percentage and fed into the extruder corresponding to the three-layer co-extrusion casting machine (layer structure is ABC). The thickness ratio of the three layers is set to 2:6:2. The temperature of extruders A and B is set to 240℃ and the temperature of extruder C is set to 230℃. A 12μm thick double-sided heat-sealed BOPP matte film without white spots or bright spots is prepared by co-extrusion casting and biaxial stretching process. The corona heat-sealing layer is corona treated with a corona machine. The surface tension of the corona heat-sealing layer after the machine is ≥42dyn.

[0090] Example 2

[0091] By weight percentage, a matte heat-sealing layer was prepared using 25% ternary random copolymer polypropylene, 25% binary random copolymer polypropylene, 42% high-density polyethylene, 3% opening slip agent, 0.05% nucleating agent, and 4.95% compatibilizer. The ternary random copolymer polypropylene (Maoming Petrochemical F8005) had a melting point of 131℃ and a melt index of 5.6 g / 10 min; the binary random copolymer polypropylene (Maoming Petrochemical F08S) had a melting point of 143℃ and a melt index of 7.5 g / 10 min; the high-density polyethylene (ExxonMobil 001) had a melting point of 125℃ and a melt index of 8.6 g / 10 min; the nucleating agent (Japan Adico NA-21); and the compatibilizer (Guangdong Lushan AP302) had a melting point of 146.5℃ and a melt index of 7.0 g / 10 min.

[0092] A support layer was prepared using 70% homopolymer polypropylene, 10% block copolymer polypropylene, and 5% compatibilizer. The homopolymer polypropylene (Zhongke Refining & Chemical F03) had a melting point of 166℃ and a melt index of 3.2 g / 10 min; the block copolymer polypropylene (Maoming Petrochemical FM100) had a melting point of 165℃ and a melt index of 2.5 g / 10 min; and the compatibilizer (Guangdong Lushan AP302) had a melting point of 146.5℃ and a melt index of 7.0 g / 10 min.

[0093] The support layer also contains 10% balancing agent and 5% modified filler.

[0094] The preparation method of the balancing agent is as follows:

[0095] S01: Add 7 parts carboxymethyl cellulose and 3 parts nano silica sol to 8 parts cerium nitrate solution, then add 3 parts silane coupling agent, stir evenly to obtain modified carboxymethyl cellulose solution;

[0096] S02: Nano-titanium oxide is preheated at 60℃ for 1 hour to obtain preheated nano-titanium oxide;

[0097] The preheated nano-titanium dioxide and modified carboxymethyl cellulose solution were stirred at a weight ratio of 3:5. After stirring, a carboxymethyl cellulose-nano-titanium dioxide blended solution was obtained.

[0098] S03: The mixture of zinc oxide whiskers / sodium alginate and carboxymethyl cellulose-nano titanium dioxide compound solution was ball-milled at a weight ratio of 5:3 for 1 hour at a speed of 1500 r / min. After ball milling, the mixture was filtered and dried to obtain the compounding agent.

[0099] In this embodiment, the cerium nitrate solution has a mass fraction of 8%; the silane coupling agent is silane coupling agent KH550; the stirring speed is 400 r / min, and the stirring time is 1 h.

[0100] The preparation method of the hybrid zinc oxide whisker / sodium alginate formulation in this embodiment is as follows:

[0101] Eight parts of zinc oxide whiskers and four parts of sodium alginate powder were added to seven parts of 5% yttrium nitrate solution, followed by three parts of boron oxide and 0.5 parts of glass fiber. The mixture was stirred evenly, filtered, and dried to obtain a mixture of zinc oxide whiskers and sodium alginate.

[0102] The preparation method of the modified filler in this embodiment is as follows:

[0103] S11: Dissolve tetrabutyl titanate in anhydrous ethanol at a weight ratio of 2:9, then add 15% of the total amount of tetrabutyl titanate silane coupling agent KH560 and 5% of the total amount of tetrabutyl titanate nano silica sol, stir evenly to obtain modified tetrabutyl titanate solution.

[0104] S12: Place the nano-attapulgite in a sodium silicate solution with a mass fraction of 5% (5 times the total amount of nano-attapulgite), and then add a urea solution with a mass fraction of 4% (15% of the total amount of nano-attapulgite). Ball mill the mixture for 2 hours at a speed of 1000 r / min. After the ball milling is completed, the pretreated nano-attapulgite is obtained.

[0105] S13: The pretreated nano-attapulgite and modified tetrabutyl titanate solution were ultrasonically modified at a weight ratio of 5:7. The modification power was 370W, and the modification was carried out for 1 hour. After the modification was completed, the mixture was filtered and dried to obtain the modified filler.

[0106] A corona heat-sealing layer was prepared using 90% ternary random copolymer polypropylene, 7% binary copolymer polypropylene, 2.95% compatibilizer, and 0.05% nucleating agent. The ternary random copolymer polypropylene (Singapore TPC FS5612) had a melting point of 133℃ and a melt index of 5.2 g / 10 min; the binary random copolymer polypropylene (Korea SK H236W) had a melting point of 150℃ and a melt index of 3.6 g / 10 min; the nucleating agent (Japan Idico NA-21) and the compatibilizer (Guangdong Lushan AP302) had melting points of 146.5℃ and melt index of 7.0 g / 10 min.

[0107] The above-mentioned heat-sealing layer, support layer and corona heat-sealing layer raw materials are blended according to weight percentage and fed into the extruder corresponding to the three-layer co-extrusion casting machine (layer structure is ABC). The thickness ratio of the three layers is set to 2:6:2. The temperature of extruders A and B is set to 240℃ and the temperature of extruder C is set to 230℃. A double-sided heat-sealed BOPP matte film with a thickness of 18μm and no white spots or bright spots is prepared by co-extrusion casting and biaxial stretching process. The corona heat-sealing layer is corona treated by a corona machine. The surface tension of the corona heat-sealing layer after the machine is ≥42dyn.

[0108] Example 3

[0109] By weight percentage, a matte heat-sealing layer was prepared using 32% ternary random copolymer polypropylene, 13% binary random copolymer polypropylene, 45% high-density polyethylene, 2.5% opening slip agent, 0.05% nucleating agent, and 7.45% compatibilizer. The ternary random copolymer polypropylene (Maoming Petrochemical F8005) had a melting point of 131℃ and a melt index of 5.6 g / 10 min; the binary random copolymer polypropylene (Shanghai Petrochemical F800E) had a melting point of 143℃ and a melt index of 7.5 g / 10 min; the high-density polyethylene (ExxonMobil 001) had a melting point of 125℃ and a melt index of 8.6 g / 10 min; the nucleating agent (Mericken NX8000); and the compatibilizer (Arkema OE825) had a melting point of 105℃ and a melt index of 2.5 g / 10 min.

[0110] A support layer was prepared using 80% homopolymer polypropylene, 5% block copolymer polypropylene, and 2.5% compatibilizer. The homopolymer polypropylene (Sichuan Petrochemical L5E89) had a melting point of 166℃ and a melt index of 3.1 g / 10 min; the block copolymer polypropylene (Maoming Petrochemical HF500) had a melting point of 166℃ and a melt index of 5.4 g / 10 min; and the compatibilizer (Guangdong Lushan AP302) had a melting point of 146.5℃ and a melt index of 7.0 g / 10 min.

[0111] The support layer also contains 8.5% balancing agent and 4% modified filler.

[0112] The preparation method of the balancing agent is as follows:

[0113] S01: Add 5.5 parts of carboxymethyl cellulose and 2 parts of nano silica sol to 6.5 parts of cerium nitrate solution, then add 2.5 parts of silane coupling agent, stir evenly to obtain modified carboxymethyl cellulose solution;

[0114] S02: Nano-titanium oxide is preheated at 57.5℃ for 1 hour to obtain preheated nano-titanium oxide;

[0115] The preheated nano-titanium dioxide and modified carboxymethyl cellulose solution were stirred at a weight ratio of 3:5. After stirring, a carboxymethyl cellulose-nano-titanium dioxide blended solution was obtained.

[0116] S03: The mixture of zinc oxide whiskers / sodium alginate and carboxymethyl cellulose-nano titanium dioxide compound solution was ball-milled at a weight ratio of 5:2.5 for 1 hour at a speed of 1500 r / min. After ball milling, the mixture was filtered and dried to obtain the compounding agent.

[0117] In this embodiment, the cerium nitrate solution has a mass fraction of 6.5%; the silane coupling agent is silane coupling agent KH550; the stirring speed is 370 r / min, and the stirring time is 1 h.

[0118] The preparation method of the hybrid zinc oxide whisker / sodium alginate formulation in this embodiment is as follows:

[0119] Add 6.5 parts of zinc oxide whiskers and 3 parts of sodium alginate powder to 5.5 parts of 5% yttrium nitrate solution, then add 2.5 parts of boron oxide and 0.45 parts of glass fiber, stir evenly, filter and dry to obtain a mixture of zinc oxide whiskers and sodium alginate.

[0120] The preparation method of the modified filler in this embodiment is as follows:

[0121] S11: Dissolve tetrabutyl titanate in anhydrous ethanol at a weight ratio of 2:8, then add 12.5% ​​of the total amount of tetrabutyl titanate silane coupling agent KH560 and 3.5% of the total amount of tetrabutyl titanate nano silica sol, stir evenly to obtain modified tetrabutyl titanate solution.

[0122] S12: Place the nano-attapulgite in a sodium silicate solution with a mass fraction of 5% (4 times the total amount of nano-attapulgite), and then add a urea solution with a mass fraction of 4% (12.5% ​​of the total amount of nano-attapulgite). Ball mill the mixture for 2 hours at a speed of 1000 r / min. After the ball milling is completed, the pretreated nano-attapulgite is obtained.

[0123] S13: The pretreated nano-attapulgite and modified tetrabutyl titanate solution were ultrasonically modified at a weight ratio of 5:7. The modification power was 360W, and the modification was carried out for 1 hour. After the modification was completed, the mixture was filtered and dried to obtain the modified filler.

[0124] A corona heat-sealing layer was prepared using 85% ternary random copolymer polypropylene, 8% binary copolymer polypropylene, 6.95% compatibilizer, and 0.05% nucleating agent. The ternary random copolymer polypropylene (Singapore TPC FL7540L) had a melting point of 131℃ and a melt index of 7.6 g / 10 min; the binary random copolymer polypropylene (Maoming Petrochemical F08M) had a melting point of 145℃ and a melt index of 7.2 g / 10 min; the nucleating agent (Shanxi Chemical Research Institute TMP-1) and the compatibilizer (Guangdong Lushan AP302) had a melting point of 146.5℃ and a melt index of 7.0 g / 10 min.

[0125] The above-mentioned heat-sealing layer, support layer and corona heat-sealing layer raw materials are blended according to weight percentage and fed into the extruder corresponding to the three-layer co-extrusion casting machine (layer structure is ABC). The thickness ratio of the three layers is set to 3:4:3. The temperature of extruders A and B is set to 240℃ and the temperature of extruder C is set to 230℃. A 45μm thick double-sided heat-sealed BOPP matte film without white spots or bright spots is prepared by co-extrusion casting and biaxial stretching process. The corona heat-sealing layer is corona treated with a corona machine. The surface tension of the corona heat-sealing layer after the machine is ≥42dyn.

[0126] The testing method is as follows:

[0127] I. Appearance inspection: Visual inspection in accordance with GB / T 2918.

[0128] II. Optical performance: According to GB / T 2410-2008, the transmittance and haze were measured using a SGW-810 photoelectric haze meter from Shanghai Instrument & Electronics Physical Optical Instrument Co., Ltd., with a C light source, in accordance with GB / T8807-1988 standard.

[0129] III. Mechanical property testing: According to GB / T 1040.3-2006, type II specimens were used, and the tensile testing was conducted using an HZ-1003B tensile testing machine from Shanghai Hengzhun Instrument Technology Co., Ltd. The tensile speed was 200 mm / min, and the elongation at break was determined.

[0130] IV. Heat sealing performance test: The BOPP matte film was tested for heat sealing performance according to the TCIAPS0005-2018 standard. The cutting temperature was set to 90℃, the heat sealing time was 1s, and the heat sealing pressure was 0.3MPa. The heat sealing temperature (i.e. the initial sealing temperature) when the heat sealing strength was ≥3N was tested.

[0131] The product performance tests for Examples 1-3 are as follows:

[0132]

[0133]

[0134] Based on the above performance tests, this invention further explores the effects of balancing agents and modified fillers:

[0135] Comparative Example 1.

[0136] Unlike Example 3, no balancing agent was added.

[0137] Comparative Example 2.

[0138] Unlike Example 3, the balancing agent did not contain a mixture of zinc oxide whiskers / sodium alginate.

[0139] Comparative Example 3.

[0140] Unlike Example 3, the carboxymethyl cellulose-nano titanium dioxide co-conditioning solution was not added to the balancing agent.

[0141] Comparative Example 4.

[0142] Unlike Example 3, no modified carboxymethyl cellulose solution was added in the preparation of the carboxymethyl cellulose-nano titanium dioxide combined solution.

[0143] Comparative Example 5.

[0144] Unlike Example 3, no carboxymethyl cellulose or nano silica sol was added to the modified carboxymethyl cellulose solution.

[0145] Comparative Example 6.

[0146] Unlike Example 3, zinc oxide whiskers and sodium alginate powder were not added in the preparation of the mixed zinc oxide whisker / sodium alginate formulation.

[0147] Comparative Example 7.

[0148] Unlike Example 3, boron oxide and glass fiber were not added in the preparation of the mixed zinc oxide whiskers / sodium alginate formulation.

[0149] Comparative Example 8.

[0150] Unlike Example 3, no modified filler was added.

[0151] Comparative Example 9.

[0152] Unlike Example 3, no pretreated nano-attapulgites were added during the preparation of the modified filler.

[0153] Comparative Example 10.

[0154] Unlike Example 3, no modified tetrabutyl titanate solution was added during the preparation of the modified filler.

[0155] The products in Comparative Examples 1-10 were further tested for performance, and the performance measurement results are as follows.

[0156]

[0157]

[0158] From Examples 1-3 and Comparative Examples 1-10, it was found that...

[0159] The product of Embodiment 3 of the present invention exhibits excellent light transmittance, haze and elongation at break under normal conditions, and also maintains excellent performance stability under 5% hydrochloric acid mist conditions.

[0160] As can be seen from Comparative Examples 1-10 and Example 3, the performance of the product deteriorates significantly when neither the balancing agent nor the modified filler is added, especially the corrosion resistance stability deteriorates significantly. The combined use of the balancing agent and the modified filler results in the most significant improvement in product performance.

[0161] The performance of products prepared by combining zinc oxide whiskers / sodium alginate with carboxymethyl cellulose-nano titanium dioxide solution, modified carboxymethyl cellulose solution, nano silica sol, zinc oxide whiskers, sodium alginate powder, boron oxide, and glass fiber in the preparation of zinc oxide whiskers / sodium alginate with the specific method of this invention shows a trend of deterioration to varying degrees. The performance of the product prepared by combining the zinc oxide whisker / sodium alginate mixture and the carboxymethyl cellulose-nano titanium dioxide solution obtained by the specific method of this invention is the most significant. Other methods are not as effective as the results of this invention.

[0162] In the preparation of modified fillers, the performance of products that do not include pretreated nano-attapulgites or modified tetrabutyl titanate solution tends to deteriorate. The modified filler obtained by the method of this invention has the most significant performance effect.

[0163] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0164] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A double-sided heat-sealable BOPP matte film, characterized in that, It includes a matte heat-sealing layer, a support layer and a corona heat-sealing layer arranged in sequence; the thickness of the BOPP matte film is 10μm~50μm, and the thickness ratio of the matte heat-sealing layer, the support layer and the corona heat-sealing layer is (1-4):(2-8):(1-4). The matte heat-sealing layer, by weight percentage, comprises 100% raw material components, including 20%~50% ternary random copolymer polypropylene, 0%~30% binary random copolymer polypropylene, 30%~70% high-density polyethylene, 1%~5% opening slip agent, 0%~0.2% nucleating agent, and 1%~10% compatibilizer; The support layer, by weight percentage, comprises 100% of the raw material components, including 70%~100% homopolymer polypropylene, 0%~30% block copolymer polypropylene, 0%~0.2% nucleating agent, 1%~10% compatibilizer, and the support layer also contains 7%~10% balancing agent and 3%~5% modified filler. The corona heat seal layer, by weight percentage, comprises 100% of the raw material components, including 0%~100% ternary random copolymer polypropylene, 0%~50% binary random copolymer polypropylene, 0%~0.2% nucleating agent, and 1%~10% compatibilizer; The preparation method of the balancing agent is as follows: S01: Add 4-7 parts by weight of carboxymethyl cellulose and 1-3 parts by weight of nano-silica sol to 5-8 parts by weight of cerium nitrate solution, then add 2-3 parts by weight of silane coupling agent, stir evenly to obtain modified carboxymethyl cellulose solution. S02: Nano-titanium oxide is preheated at 55~60℃ for 1 hour to obtain preheated nano-titanium oxide; The preheated nano-titanium dioxide and modified carboxymethyl cellulose solution were stirred at a weight ratio of 3:

5. After stirring, a carboxymethyl cellulose-nano-titanium dioxide mixed solution was obtained. S03: The mixture of zinc oxide whiskers / sodium alginate and carboxymethyl cellulose-nano titanium dioxide compound solution were ball-milled at a weight ratio of 5:(2~3) for 1 hour at a speed of 1500 r / min. After ball milling, the mixture was filtered and dried to obtain the compounding agent. The preparation method of the hybrid zinc oxide whisker / sodium alginate formulation is as follows: Add 5-8 parts by weight of zinc oxide whiskers and 2-4 parts by weight of sodium alginate powder to 4-7 parts by weight of 5% yttrium nitrate solution, then add 2-3 parts by weight of boron oxide and 0.4-0.5 parts by weight of glass fiber, stir evenly, filter and dry to obtain a mixture of zinc oxide whiskers and sodium alginate. The preparation method of the modified filler is as follows: S11: Dissolve tetrabutyl titanate in anhydrous ethanol at a weight ratio of 2:(7~9), then add 10~15% of the total amount of tetrabutyl titanate silane coupling agent KH560 and 2~5% of the total amount of tetrabutyl titanate nano silica sol, stir evenly to obtain modified tetrabutyl titanate solution. S12: Place the nano-attapulgite in a sodium silicate solution with a mass fraction of 5% (3-5 times the total weight of the nano-attapulgite), and then add a urea solution with a mass fraction of 4% (10-15% of the total weight of the nano-attapulgite). Ball mill the mixture for 2 hours at a speed of 1000 r / min. After the ball milling is completed, the pretreated nano-attapulgite is obtained. S13: Pretreated nano-attapulgite clay and modified tetrabutyl titanate solution are ultrasonically modified at a weight ratio of 5:7 with an ultrasonic power of 350~370W for 1 hour. After modification, the mixture is filtered and dried to obtain the modified filler.

2. The double-sided heat-sealable BOPP matte film according to claim 1, characterized in that, The opening slip agent is silica with a particle size of 0.5μm~4μm; The nucleating agent is one or more of the following: aryl amide nucleating agents, sorbitol nucleating agents, branched acid amine transparent nucleating agents, aryl phosphate transparent nucleating agents, carboxylic acid metal salt transparent nucleating agents, dehydropolar acids and their salts nucleating agents; The compatibilizer is one or more of the following: maleic anhydride graft compatibilizer, cyclic anhydride compatibilizer, carboxylic acid compatibilizer, oxazoline compatibilizer, imide compatibilizer, ethylene propylene rubber, POE, EVA, and isocyanate compatibilizer.

3. The double-sided heat-sealable BOPP matte film according to claim 2, characterized in that, The high-density polyethylene has a melting point of 125℃~135℃ and a melt index of 5~15g / 10min at 190℃ and 21.6kg. The ternary random copolymer polypropylene has a melting point of 125℃~135℃, and a melt index of 2~9g / 10min at 230℃ and 2.16kg. The binary random copolymer polypropylene has a melting point of 135℃~150℃, and a melt index of 4~18g / 10min at 230℃ and 2.16kg. The homopolymer polypropylene has a melting point ≥160℃ and a melt index of 2~8g / 10min; The selected block copolymer polypropylene has a melting point ≥163℃ and a melt index of 1~8g / 10min.

4. The double-sided heat-sealable BOPP matte film according to claim 3, characterized in that, The high-density polyethylene has a melt index of 6~10g / 10min at 190℃ and 21.6kg. The melt flow index of the ternary random copolymer polypropylene at 230℃ and 2.16 kg is 3~7 g / 10 min; The binary random copolymer polypropylene has a melt index of 6~16g / 10min at 230℃ and 2.16kg. The melt index of the homopolymer polypropylene is 3~5 g / 10min; The selected block copolymer polypropylene has a melt index of 2~5 g / 10min.

5. The double-sided heat-sealable BOPP matte film according to claim 4, characterized in that, The cerium nitrate solution has a mass fraction of 5-8%; the silane coupling agent is silane coupling agent KH550; the stirring speed is 350-400 r / min, and the stirring time is 1 h.

6. A method for preparing a double-sided heat-sealable BOPP matte film according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Weigh the raw materials for the photothermal seal layer, the support layer, and the corona heat seal layer by weight percentage; (2) The raw materials of the matte heat-sealing layer, the support layer and the corona heat-sealing layer are respectively fed into the A, B and C extruders of the three-layer co-extrusion casting machine. After adjusting the equipment according to the layer thickness ratio and the extruder processing temperature, the machine is started. Thin sheets are prepared by co-extrusion casting process, and then bi-directional stretching is carried out by bi-stretching process to obtain BOPP matte film.

7. The method for preparing a double-sided heat-sealable BOPP matte film according to claim 6, characterized in that, In step (2), the extrusion temperature of extruders A and B is 240℃, and the extrusion temperature of extruder C is 230℃; longitudinal stretching: preheating temperature 115-120℃, stretching ratio 5:1; transverse stretching: preheating zone 125-130℃, stretching ratio 10:1, setting temperature 155℃.

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