Polyester barrier material for food packaging as well as preparation method and application of polyester barrier material

Abstract

The invention belongs to the technical field of food packaging materials, and particularly relates to a polyester barrier material for food packaging and a preparation method and application thereof. The polyester barrier material for food packaging is prepared from the following components in percentage by mass: 85 to 90 percent of first PET (Polyethylene Terephthalate) resin, 5 to 10 percent of double-coated modified calcium carbonate, 1 to 3 percent of titanium dioxide, 0.5 to 1.5 percent of compatilizer, 0.1 to 0.5 percent of lubricant and 0.1 to 0.5 percent of antioxidant, the polyester barrier material for food packaging provided by the invention has the advantages of low titanium dioxide content, good light blocking effect, good oxygen barrier property and good forming effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food packaging materials, and particularly relates to a polyester barrier material for food packaging and a preparation method and application thereof. BACKGROUND

[0002] Food is susceptible to light, oxygen, moisture and microorganisms during storage, transportation and shelf life, which leads to adverse changes in color, odor, texture and the like, not only shortening the shelf life, but also possibly causing food safety risks. Therefore, selecting a food packaging material with good barrier properties is an important means to ensure food quality and extend the shelf life of food.

[0003] Polyethylene terephthalate is widely used in food packaging due to its good mechanical properties, transparency, chemical resistance and gas barrier properties. The requirements of food packaging vary greatly due to the variety of food types. For the packaging of dairy products, fruit / vegetable juice drinks and the like, not only good gas barrier properties are required, but also good light barrier properties are required due to the inherent sensitivity of dairy products, fruit / vegetable juice drinks to light.

[0004] Titanium dioxide is usually added to achieve the light barrier property of the barrier material in the prior art. For example, a high-cleanliness polyester master batch is disclosed in Chinese Patent No. CN119432019A, which uses silicon dioxide as an opening agent and is ground with BOPET, pre-mixed, stirred, and then melt-extruded through a mixing granulation device to obtain the master batch. Chinese Patent No. CN110591301A discloses a high-light-barrier master batch for PET packaging and a preparation method thereof. The technical solution uses PET resin as a basic carrier resin to ensure good compatibility of the light barrier master batch with the PET finished product resin, and also adds a certain amount of PP resin to improve the problem of brittleness of PET preforms and PET finished product bottles caused by high titanium dioxide content in the finished product bottles.

[0005] However, the light barrier effect of titanium dioxide is limited and has safety risks. The proportion of titanium dioxide in the above technical solutions is relatively high, which has the risk of migration, and the content of the light barrier material is relatively high, which has the problem of difficulty in dispersibility, resulting in difficulty in obtaining a packaging material with uniform wall thickness. In addition, the above technical solutions do not pay attention to the oxygen barrier property. SUMMARY

[0006] To solve the above technical problems, the purpose of the present application is to provide a polyester barrier material for food packaging and a preparation method and application thereof. The polyester barrier material for food packaging provided by the present application has the advantages of low titanium dioxide content, good light barrier effect, good oxygen barrier property and good forming effect.

[0007] To achieve this purpose, the following technical solutions are adopted in the present application: In a first aspect, the present application provides a polyester barrier material for food packaging, comprising the following components in mass percentage: 85-90% of first PET resin, 5-10% of double-coated modified calcium carbonate, 1-3% of titanium dioxide, 0.5-1.5% of compatibilizer, 0.1-0.5% of lubricant, and 0.1-0.5% of antioxidant. The preparation method of the double-coated modified calcium carbonate comprises the following steps: (1) dissolving the second PET resin in chloroform, adding calcium carbonate A, stirring, drying, and obtaining PET resin-coated calcium carbonate A; (2) adding the PET resin-coated calcium carbonate A into an ethanol solution of calcium carbonate B, stirring, drying, and heat treating to obtain polyester-coated calcium carbonate A loaded with calcium carbonate B; (3) stirring and mixing the polyester-coated calcium carbonate A loaded with calcium carbonate B, methyl methacrylate, and water to obtain a mixed solution, adding a styrene n-hexane solution and an initiator into the mixed solution under nitrogen protection, and reacting at elevated temperature, filtering, washing, and drying to obtain coated modified calcium carbonate.

[0008] In some preferred embodiments, the intrinsic viscosity of the first PET resin is 0.75-0.8 dL / g.

[0009] In some preferred embodiments, the melting point of the second PET resin is 110-130℃.

[0010] In some preferred embodiments, the calcium carbonate A is a spindle-shaped light calcium carbonate.

[0011] In some preferred embodiments, the average particle size of the spindle-shaped light calcium carbonate is 3-4 µm.

[0012] In some preferred embodiments, the calcium carbonate B is a cubic nanometer calcium carbonate.

[0013] In some preferred embodiments, the average particle size of the cubic nanometer calcium carbonate is 50-100 nm.

[0014] In some preferred embodiments, the initiator is selected from at least one of t-butyl peroxide, benzoyl peroxide, t-butyl peroxyacetate, cumene hydroperoxide, methyl ethyl ketone peroxide, and t-butyl peroxybenzoate.

[0015] In some preferred embodiments, the mass ratio of the second PET resin, calcium carbonate A, and calcium carbonate B is 0.8-1.2:7-8:1.2-1.8.

[0016] In some preferred embodiments, the mass ratio of the second PET resin and chloroform is 5-10:100.

[0017] In some preferred embodiments, the temperature of the stirring in step (1) is 60-70°C, the rotation speed is 100-200 rpm, and the time is 1-2 h.

[0018] In some preferred embodiments, the mass concentration of the calcium carbonate B ethanol solution is 10-20%.

[0019] In some preferred embodiments, the temperature of the stirring in step (2) is 25-30°C, the rotation speed is 100-200 rpm, and the time is 0.5-1 h.

[0020] In some preferred embodiments, the temperature of the heat treatment in step (2) is 110-130°C, and the time is 10-30 min.

[0021] In some preferred embodiments, the mass ratio of the calcium carbonate B loaded polyester coated calcium carbonate A, methyl methacrylate, and styrene is 10-15:20-25:5-10.

[0022] In some preferred embodiments, the mass ratio of the calcium carbonate B loaded polyester coated calcium carbonate A and water is 10-15:100.

[0023] In some preferred embodiments, the volume ratio of styrene and n-hexane in the styrene n-hexane solution is 1:3-5.

[0024] In some preferred embodiments, the amount of the initiator is 0.5-2% of the total mass of the methyl methacrylate and styrene.

[0025] In some preferred embodiments, the temperature of the temperature increasing reaction in step (3) is 80-90°C, and the time is 1-2 h.

[0026] In some preferred embodiments, the titanium white is rutile titanium white.

[0027] In some preferred embodiments, the compatibilizer is selected from at least one of maleic anhydride grafted polyolefin elastomer and glycidyl methacrylate grafted polyolefin elastomer.

[0028] In some preferred embodiments, the lubricant is selected from at least one of polyethylene wax, calcium stearate, magnesium stearate, zinc stearate, ethylene bis-stearamide, and pentaerythritol stearate.

[0029] In some preferred embodiments, the antioxidant is selected from at least one of hindered phenol antioxidant and organic phosphite antioxidant.

[0030] In a second aspect, the application provides a preparation method of the food packaging polyester barrier material according to the first aspect, comprising the following steps: mixing the first PET resin, the double-coated modified calcium carbonate, the titanium white, the compatilizer, the lubricant and the antioxidant, drying, heating and melting, and extruding and granulating to obtain the food packaging polyester barrier material.

[0031] In a third aspect, the application provides an application of the food packaging polyester barrier material according to the first aspect in the packaging of dairy products and fruit / vegetable juice drinks.

[0032] Compared with the prior art, the application has the following beneficial effects: The application creatively prepares the double-coated calcium carbonate to replace the titanium white and reduce the amount of the titanium white, coats the calcium carbonate A with the second PET resin with a low melting point, loads the calcium carbonate B on the calcium carbonate A coated with the second PET resin, and coats the calcium carbonate A and the calcium carbonate B again with the methyl methacrylate-styrene copolymer resin, wherein the loading structure formed by the calcium carbonate A and the calcium carbonate B increases the rough surface, thereby improving the scattering of light and the barrier to oxygen; the coating layer of the methyl methacrylate-styrene copolymer resin improves the dispersibility of the calcium carbonate and further increases the irregular interface effect after the polyester barrier material is blown into a bottle, thereby improving the scattering of light; the double-coated calcium carbonate enables the PET bottle to have excellent light-blocking effect, excellent oxygen-blocking performance and uniform wall thickness.

[0033] If only the second PET resin is used to coat the calcium carbonate A and load the calcium carbonate B, the coated second PET resin will be re-melted with the first PET resin in the melting process due to the compatibility of the second PET resin and the first PET resin, the calcium carbonate is re-dispersed, causing agglomeration, and the light-blocking performance, the oxygen-blocking performance and the uniformity of the wall thickness of the polyester barrier material are all reduced; if only the methyl methacrylate-styrene copolymer resin is used for coating, the calcium carbonate A and the calcium carbonate B cannot form a loading effect, and the light-blocking and oxygen-blocking performances of the polyester barrier material cannot be improved, while the double-coated calcium carbonate of the application can make the two modification methods achieve the effect of 1+1>2. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a physical diagram of the PET bottle formed by injection molding and blow molding of the food packaging polyester barrier material of Example 1. Figure 2 It is an inspection report of the food packaging polyester barrier material of Example 1. DETAILED DESCRIPTION

[0035] In order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0036] The raw materials, reagents or devices used in the following examples and comparative examples are commercially available or can be obtained by known methods unless otherwise specified.

[0037] Preparation Example Preparation Example 1 A double-coated modified calcium carbonate is prepared by the following preparation method: (1) Dissolve the second PET resin in chloroform at 70°C, add calcium carbonate A, stir at 200 rpm at 60°C for 2 h, dry, and obtain PET resin-coated calcium carbonate A; (2) Add the PET resin-coated calcium carbonate A to the ethanol solution of calcium carbonate B, stir at 100 rpm at 25°C for 30 min, dry, and heat treat at 120°C for 30 min to obtain polyester-coated calcium carbonate A loaded with calcium carbonate B; (3) Stir and mix the polyester-coated calcium carbonate A loaded with calcium carbonate B, methyl methacrylate, and water to obtain a mixture, add the n-hexane solution of styrene and hydrogen peroxide cumene to the mixture under nitrogen protection, heat to 85°C, and react for 1.5 h, filter, wash, and dry to obtain the coated modified calcium carbonate.

[0038] The melting point of the second PET resin is 115±5°C, and the model number is UB-304 from TINOPURE MATERIALS TECHNOLOGY CO., LTD.

[0039] The calcium carbonate A is a spindle-shaped light calcium carbonate with an average particle size of 3.5 µm, and the model number is MP-3 from Guangxi Huana New Materials Co., Ltd.

[0040] The calcium carbonate B is a cubic nanometer calcium carbonate with an average particle size of 65 nm, and the model number is nanometer calcium carbonate (plastic master batch) from Shandong Yuxin Nanometer Technology Co., Ltd.

[0041] The mass ratio of the second PET resin, calcium carbonate A, and calcium carbonate B is 1:7.5:1.5.

[0042] The mass ratio of the second PET resin and chloroform is 10:100.

[0043] The mass concentration of the ethanol solution of calcium carbonate B is 15%.

[0044] The mass ratio of the polyester-coated calcium carbonate A loaded with calcium carbonate B, methyl methacrylate, and styrene is 12:22:8.

[0045] The mass ratio of the polyester-coated calcium carbonate A and water is 10:100.

[0046] The volume ratio of styrene and n-hexane in the styrene n-hexane solution is 1:4.

[0047] The amount of cumene hydroperoxide is 1% of the total mass of methyl methacrylate and styrene.

[0048] Preparation Example 2 A double-coated modified calcium carbonate is prepared by the following preparation method: (1) Dissolve the second PET resin in chloroform at 70°C, add calcium carbonate A, stir at 200 rpm at 60°C for 2h, dry, and obtain PET resin-coated calcium carbonate A; (2) Stir and mix the PET resin-coated calcium carbonate A, methyl methacrylate, and water to obtain a mixed solution, add the styrene n-hexane solution and cumene hydroperoxide to the mixed solution under nitrogen protection, heat to 85°C and react for 1.5h, filter, wash, and dry to obtain the coated modified calcium carbonate.

[0049] The melting point of the second PET resin is 115±5°C, and the model number is UB-304 from TINUSOFT (QINGDAO) NEW MATERIALS CO., LTD.

[0050] The calcium carbonate A is a spindle-shaped light calcium carbonate with an average particle size of 3.5µm, and the model number is MP-3 from Guangxi Huwana New Materials Co., Ltd.

[0051] The mass ratio of the second PET resin and calcium carbonate A is 1:9.

[0052] The mass ratio of the second PET resin and chloroform is 10:100.

[0053] The mass ratio of the PET resin-coated calcium carbonate A, methyl methacrylate, and styrene is 12:22:8.

[0054] The mass ratio of the PET resin-coated calcium carbonate A and water is 10:100.

[0055] The volume ratio of styrene and n-hexane in the styrene n-hexane solution is 1:4.

[0056] The amount of cumene hydroperoxide is 1% of the total mass of methyl methacrylate and styrene.

[0057] Preparation Example 3 A double-coated modified calcium carbonate is prepared by the following preparation method:

[0058] Preparation Example 4 A double-coated modified calcium carbonate, the only difference from Preparation Example 1 being that the calcium carbonate A is heavy calcium carbonate, Shandong Yuxin Nanometer Technology Co., Ltd., Model: Heavy Calcium Carbonate (Plastic); the rest are the same.

[0059] Preparation Example 5 A single-layer coated modified calcium carbonate, prepared by the following preparation method: (1) Dissolve the second PET resin in chloroform at 70°C, add calcium carbonate A, stir at 200 rpm at 60°C for 2 h, dry, and obtain PET resin-coated calcium carbonate A; (2) Add the PET resin-coated calcium carbonate A to the ethanol solution of calcium carbonate B, stir at 100 rpm at 25°C for 30 min, dry, and heat treat at 120°C for 30 min to obtain the single-layer coated modified calcium carbonate.

[0060] The melting point of the second PET resin is 115±5°C, Wuxi Youmei New Material Technology Co., Ltd., Model: UB-304.

[0061] The calcium carbonate A is spindle light calcium carbonate, with an average particle size of 3.5 µm, Guangxi Huawana New Material Co., Ltd., Model: MP-3.

[0062] The calcium carbonate B is cubic nano calcium carbonate, with an average particle size of 65 nm, Shandong Yuxin Nanometer Technology Co., Ltd., Model: Nano Calcium Carbonate (Plastic Master Batch).

[0063] The mass ratio of the second PET resin, calcium carbonate A, and calcium carbonate B is 1:7.5:1.5.

[0064] The mass ratio of the second PET resin and chloroform is 10:100.

[0065] The mass concentration of the ethanol solution of calcium carbonate B is 15%.

[0066] Preparation Example 6 A single-layer coated modified calcium carbonate, prepared by the following preparation method: Mix calcium carbonate A, calcium carbonate B, methyl methacrylate, and water to obtain a mixed solution, add the n-hexane solution of styrene and cumene hydroperoxide to the mixed solution under nitrogen protection, heat to 85°C and react for 1.5 h, filter, wash, and dry to obtain the single-layer coated modified calcium carbonate.

[0067] The calcium carbonate A is spindle light calcium carbonate, with an average particle size of 3.5 µm, Guangxi Huawana New Material Co., Ltd., Model: MP-3.

[0068] The calcium carbonate B is cubic nano calcium carbonate with an average particle size of 65 nm, from Shandong Yuxin Nanometer Technology Co., Ltd., model: nano calcium carbonate (plastic master batch).

[0069] The mass ratio of the calcium carbonate A, the calcium carbonate B, the methyl methacrylate and the styrene is 10:2:22:8.

[0070] The mass ratio of the total mass of the calcium carbonate A and the calcium carbonate B and the water is 10:100.

[0071] The volume ratio of the styrene and the n-hexane in the styrene n-hexane solution is 1:4.

[0072] The amount of the cumene hydroperoxide is 1% of the total mass of the methyl methacrylate and the styrene.

[0073] Embodiment Embodiment 1

[0074] A polyester barrier material for food packaging, comprising the following components in mass percentage: 88% of first PET resin, 8% of double-coated modified calcium carbonate of Preparation Example 1, 2% of titanium dioxide, 1% of compatibilizer, 0.5% of lubricant, and 0.5% of antioxidant. The intrinsic viscosity of the first PET resin is 0.79 dL / g, from Wanke New Material Co., Ltd., model: WK-811.

[0075] The titanium dioxide is rutile titanium dioxide, from Jiangsu Taibai Group Co., Ltd., model: ZR-965.

[0076] The compatibilizer is maleic anhydride grafted polyolefin elastomer, trade name: Mitsui Chemical MH5040.

[0077] The lubricant is ethylene bis-stearamide.

[0078] The antioxidant is antioxidant 1010.

[0079] The preparation method of the above-mentioned polyester barrier material for food packaging, comprising the following steps: mixing the first PET resin, the double-coated modified calcium carbonate, the titanium dioxide, the compatibilizer, the lubricant and the antioxidant, drying, heating and melting, extruding and granulating, to obtain the polyester barrier material for food packaging.

[0080] The test report of the polyester barrier material for food packaging of this embodiment is shown in Table 1. Figure 2

[0081] Embodiment 2

[0082] ​A polyester barrier material for food packaging comprises the following components by mass percentage: first PET resin 87.5%, double-coated modified calcium carbonate of Preparation Example 1 7%, titanium dioxide 3%, compatibilizer 1.5%, lubricant 0.5%, antioxidant 0.5%; The intrinsic viscosity of the first PET resin is 0.79 dL / g, and the model number is WK-811 from Wanke New Material Co., Ltd.

[0083] The titanium dioxide is rutile titanium dioxide, and the model number is ZR-965 from Jiangsu Taibai Group Co., Ltd.

[0084] The compatibilizer is maleic anhydride grafted polyolefin elastomer, and the trade name is Mitsui Chemical MH5040.

[0085] The lubricant is ethylene bis-stearamide.

[0086] The antioxidant is antioxidant 1010.

[0087] The preparation method of the above-mentioned polyester barrier material for food packaging comprises the following steps: mixing the first PET resin, the double-coated modified calcium carbonate, the titanium dioxide, the compatibilizer, the lubricant, and the antioxidant, drying, heating and melting, and extruding and granulating to obtain the polyester barrier material for food packaging.

[0088] Example 3

[0089] A polyester barrier material for food packaging comprises the following components by mass percentage: first PET resin 87.5%, double-coated modified calcium carbonate of Preparation Example 1 7%, titanium dioxide 3%, compatibilizer 1.5%, lubricant 0.5%, antioxidant 0.5%; The intrinsic viscosity of the first PET resin is 0.79 dL / g, and the model number is WK-811 from Wanke New Material Co., Ltd.

[0090] The titanium dioxide is rutile titanium dioxide, and the model number is ZR-965 from Jiangsu Taibai Group Co., Ltd.

[0091] The compatibilizer is maleic anhydride grafted polyolefin elastomer, and the trade name is Mitsui Chemical MH5040.

[0092] The lubricant is ethylene bis-stearamide.

[0093] The antioxidant is antioxidant 1010.

[0094] The preparation method of the above-mentioned polyester barrier material for food packaging comprises the following steps: mixing the first PET resin, the double-coated modified calcium carbonate, the titanium dioxide, the compatibilizer, the lubricant, and the antioxidant, drying, heating and melting, and extruding and granulating to obtain the polyester barrier material for food packaging.

[0095] Comparative Example 1 A polyester barrier material for food packaging, which is different from Example 1 only in that the double-coated modified calcium carbonate of Preparation Example 1 is replaced by the same mass of the double-coated modified calcium carbonate of Preparation Example 2; the rest is the same.

[0096] Comparative Example 2 A polyester barrier material for food packaging, which is different from Example 1 only in that the double-coated modified calcium carbonate of Preparation Example 1 is replaced by the same mass of the double-coated modified calcium carbonate of Preparation Example 3; the rest is the same.

[0097] Comparative Example 3 A polyester barrier material for food packaging, which is different from Example 1 only in that the double-coated modified calcium carbonate of Preparation Example 1 is replaced by the same mass of the double-coated modified calcium carbonate of Preparation Example 4; the rest is the same.

[0098] Comparative Example 4 A polyester barrier material for food packaging, which is different from Example 1 only in that the double-coated modified calcium carbonate of Preparation Example 1 is replaced by the same mass of the single-coated modified calcium carbonate of Preparation Example 5; the rest is the same.

[0099] Comparative Example 5 A polyester barrier material for food packaging, which comprises the following mass percentages of components: first PET resin 80%, styrene-methyl methacrylate copolymer resin 8%, single-coated modified calcium carbonate of Preparation Example 5 8%, titanium white 2%, compatibilizer 1%, lubricant 0.5%, antioxidant 0.5%; The intrinsic viscosity of the first PET resin is 0.79 dL / g, Wanqixin Material Co., Ltd., Model: WK-811.

[0100] The titanium white is rutile titanium white, Jiangsu Taibai Group Co., Ltd., Model: ZR-965.

[0101] The compatibilizer is maleic anhydride grafted polyolefin elastomer, trade name: Mitsui Chemical MH5040.

[0102] The lubricant is ethylene bis-stearamide.

[0103] The antioxidant is antioxidant 1010.

[0104] The preparation method of the above-mentioned polyester barrier material for food packaging comprises the following steps: mixing the first PET resin, styrene-methyl methacrylate copolymer resin (trade name: Asahi Chemical TX-100S), single-coated modified calcium carbonate, titanium white, compatibilizer, lubricant and antioxidant, drying, heating and melting, extruding and granulating to obtain the polyester barrier material for food packaging.

[0105] Comparative Example 6 A polyester barrier material for food packaging, the only difference from Example 1 is that the double-coated modified calcium carbonate of Preparation Example 1 is replaced by the same mass of single-coated modified calcium carbonate of Preparation Example 6; the rest is the same.

[0106] Application Example The polyester barrier materials for food packaging of Examples 1-3 and Comparative Examples 1-6 above were injection molded and blow molded into PET bottles with a wall thickness of 0.3 mm. The physical map of the PET bottle injection molded and blow molded from the polyester barrier material for food packaging of Example 1 is shown in FIG. 1, and the following performance tests were conducted: Figure 1 1. Light blocking performance: cut 2.5 cm x 5 cm slices and detect the light transmittance of 200-800 nm using a spectrophotometer; 2. Oxygen barrier performance: according to GB / T 1038.1-2022 "Plastic products - Film and sheet - Determination of gas transmission - Part 1: Differential pressure method", the oxygen transmission of the blow molded PET bottle was detected.

[0107] 3. Wall thickness uniformity: the wall thickness values at distances of 20 mm, 70 mm, and 120 mm from the bottom of the PET bottle were detected; three samples were selected and their corresponding wall thickness values were detected, and then the average value was taken.

[0108] The test results are shown in Table 1 below.

[0109] Table 1

[0110] Result analysis: from Table 1, it can be seen that the PET bottles prepared from the polyester barrier materials for food packaging of Examples 1-3 of the present application have excellent light blocking performance, oxygen barrier performance, and wall thickness uniformity; Comparative Example 1 lacks the loading of nano calcium carbonate B, and the wall thickness uniformity of the obtained PET bottle is not affected, but the light blocking performance and oxygen barrier performance decrease; Comparative Example 2 uses heavy calcium carbonate B, and the oxygen barrier performance of the obtained PET bottle is not affected, but the light blocking performance and wall thickness uniformity decrease; Comparative Example 3 uses heavy calcium carbonate A, and the oxygen barrier performance and wall thickness uniformity are less affected, but the light blocking performance decreases significantly; Comparative Example 4 uses single-coated modified calcium carbonate without styrene-methyl methacrylate copolymer coating, and the light blocking performance, oxygen barrier performance, and wall thickness uniformity of the obtained PET bottle decrease; ​Although Comparative Example 5 uses a single-layer coated modified calcium carbonate + styrene-methyl methacrylate copolymer resin, which improves the light blocking performance, oxygen blocking performance and wall thickness uniformity compared to Comparative Example 4, it is significantly worse than Examples 1-3. Comparative Example 6, due to the use of single-layer coated modified calcium carbonate without PET resin coating, resulted in a decrease in the light blocking performance, oxygen barrier performance, and wall thickness uniformity of the PET bottle.

[0111] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A polyester barrier material for food packaging, characterized by, The components include the following mass percentages: 85-90% of the first PET resin, 5-10% of the double-coated modified calcium carbonate, 1-3% of titanium dioxide, 0.5-1.5% of the compatibilizer, 0.1-0.5% of the lubricant, and 0.1-0.5% of the antioxidant. The preparation method of the double-coated modified calcium carbonate comprises the following steps: (1) dissolving the second PET resin in chloroform, adding calcium carbonate A, stirring, drying, and obtaining PET resin-coated calcium carbonate A; (2) adding the PET resin-coated calcium carbonate A into an ethanol solution of calcium carbonate B, stirring, drying, and heat treating to obtain polyester-coated calcium carbonate A loaded with calcium carbonate B; (3) stirring and mixing the polyester-coated calcium carbonate A loaded with calcium carbonate B, methyl methacrylate, and water to obtain a mixed solution, adding a styrene n-hexane solution and an initiator into the mixed solution under nitrogen protection, and reacting at a high temperature, filtering, washing, and drying to obtain the coated modified calcium carbonate.

2. The polyester barrier material for food packaging according to claim 1, characterized by, The intrinsic viscosity of the first PET resin is 0.75-0.8 dL / g, and the melting point of the second PET resin is 110-130℃.

3. The polyester barrier material for food packaging according to claim 2, characterized by, The calcium carbonate A is a spindle light calcium carbonate, and the average particle size of the spindle light calcium carbonate is 3-4 µm.

4. The polyester barrier material for food packaging according to claim 3, characterized by The calcium carbonate B is a cubic nanometer calcium carbonate, and the average particle size of the cubic nanometer calcium carbonate is 50-100 nm.

5. The food packaging polyester barrier material according to any one of claims 1 to 4, characterized in that, The mass ratio of the second PET resin, calcium carbonate A, and calcium carbonate B is 0.8-1.2:7-8:1.2-1.

8.

6. The food packaging polyester barrier material according to any one of claims 1 to 4, characterized in that, The mass ratio of the polyester-coated calcium carbonate A loaded with calcium carbonate B, methyl methacrylate, and styrene is 10-15:20-25:5-10.

7. The polyester barrier material for food packaging according to claim 1, characterized by, The compatibilizer is at least one selected from maleic anhydride grafted polyolefin elastomer and glycidyl methacrylate grafted polyolefin elastomer.

8. The polyester barrier material for food packaging according to claim 1, characterized by, The lubricant is at least one selected from polyethylene wax, calcium stearate, magnesium stearate, zinc stearate, ethylene bis-stearamide, and pentaerythritol stearate.

9. The method of producing a food packaging polyester barrier material according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: mixing the first PET resin, the double-coated modified calcium carbonate, titanium dioxide, the compatibilizer, the lubricant, and the antioxidant, drying, heating and melting, and extruding and granulating to obtain the polyester barrier material for food packaging.

10. The polyester barrier material for food packaging according to any one of claims 1-8 for use in packaging of dairy products and fruit / vegetable juice drinks.

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