Double-sided matte polypropylene synthetic paper, preparation method thereof, and application in TPU hot melt adhesive

Abstract

The present invention discloses a double-sided matte polypropylene synthetic paper, its preparation method, and its application in TPU hot-melt adhesives, belonging to the field of synthetic paper technology. The synthetic paper comprises an outer layer, an intermediate layer, and an inner layer. The outer layer comprises the following raw materials in parts by weight: 40-50 parts polypropylene, 0.4-0.8 parts antioxidant, 30-35 parts calcium carbonate, 2-3 parts titanium dioxide, 3-5 parts water repellent, 1-2 parts matte flour, 0.5-1 parts lubricant, and 2-4 parts antistatic agent; the intermediate layer comprises the following raw materials in parts by weight: 30-50 parts polypropylene, 2-6 parts calcium carbonate, and 1-2 parts titanium dioxide; the inner layer comprises the same raw materials and in the same proportions as the outer layer. The double-sided matte polypropylene synthetic paper prepared by the present invention exhibits excellent waterproof and antibacterial properties.

Description

Technical Field

[0001] The present invention relates to the technical field of synthetic paper, and in particular to a double-sided matte polypropylene synthetic paper, a preparation method thereof, and an application thereof in TPU hot melt adhesive. Background Art

[0002] Polypropylene (PP) synthetic paper has many advantages, including low carbon and environmental protection, low specific gravity, high strength, good weather resistance, excellent tear resistance, soft texture, excellent printing performance and durability. It has been widely used in high-quality printing, high-end packaging and special uses. With the increase in the application scenarios of polypropylene synthetic paper, more requirements are placed on polypropylene synthetic paper. Although ordinary polypropylene synthetic paper has certain advantages over traditional paper in terms of durability and chemical resistance, it may still experience water penetration when exposed to water for a long time or in high humidity environments, affecting its normal use. Due to its high cost-effectiveness, PP synthetic paper has become the preferred release material for TPU hot melt adhesives. When used as a release material, the surface of the PP synthetic paper needs to be made into a matte structure. When TPU hot melt adhesives are stored for a long time, the PP synthetic paper also needs to have certain antibacterial properties.

[0003] Chinese invention patent publication number CN117841495A discloses a polypropylene synthetic paper with ultra-high interlayer bonding strength and its preparation method. The polypropylene synthetic paper comprises an outer layer, an intermediate layer, and an inner layer. The outer layer comprises the following raw materials in parts by weight: 20-30 parts polypropylene I, 2-4 parts titanium dioxide, and 2-4 parts calcium carbonate; the intermediate layer comprises 20-30 parts polypropylene II, 2-4 parts titanium dioxide, and 10-20 parts methyl methacrylate-based copolymer; the inner layer comprises the same raw materials and parts as the outer layer. This synthetic paper exhibits excellent tensile strength and interlayer bonding strength, but has poor antibacterial properties. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a double-sided matte polypropylene synthetic paper and a preparation method thereof and application in TPU hot melt adhesive.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A double-sided matte polypropylene synthetic paper, comprising an outer layer, an intermediate layer, and an inner layer. The outer layer comprises the following raw materials in parts by weight: polypropylene: 40-50 parts, antioxidant: 0.4-0.8 parts, calcium carbonate: 30-35 parts, titanium dioxide: 2-3 parts, water repellent: 3-5 parts, matte flour: 1-2 parts, lubricant: 0.5-1 parts, and antistatic agent: 2-4 parts;

[0007] The intermediate layer comprises the following raw materials in parts by weight: polypropylene: 30-50 parts, calcium carbonate: 2-6 parts, titanium dioxide: 1-2 parts;

[0008] The material and quantity of the inner surface layer are the same as those of the outer surface layer;

[0009] The water repellent is prepared by the following method:

[0010] S1: Pentaerythritol reacts with 3,6-dimethyl-1,4-dioxane-2,5-dione under the catalysis of stannous octoate to form a four-arm compound;

[0011] S2: The four-arm compound reacts with 5-(4-bromophenyl)-1-methylimidazole to form an imidazole-modified four-arm compound;

[0012] S3: The imidazole-modified four-arm compound reacts with perfluorododecanoic acid to form a water repellent.

[0013] The molar ratio of pentaerythritol to 3,6-dimethyl-1,4-dioxane-2,5-dione in step S1 is 1:(12-20).

[0014] The molar ratio of the four-arm compound to 5-(4-bromophenyl)-1-methylimidazole in step S2 is 1:(2-2.2).

[0015] The molar ratio of the imidazole-modified four-arm compound to perfluorododecanoic acid in step S3 is 1:(1-1.2).

[0016] The lubricant is prepared by the following method:

[0017] A1: Epoxidized soybean oil reacts with octadecylamine to produce long-chain alkyl-modified soybean oil;

[0018] A2: Long-chain alkyl-modified soybean oil reacts with amino-modified silica to produce a lubricant.

[0019] The molar ratio of the epoxy soybean oil to octadecylamine in step A1 is 1:4; the mass ratio of the long-chain alkyl-modified soybean oil to amino-modified silica in step A2 is 1:1.5.

[0020] The antioxidant is one of antioxidant 702, antioxidant 1010, and antioxidant 1076; the antistatic agent is one of AS11N antistatic agent and Armostat 400 antistatic agent.

[0021] The mist flour is prepared by mixing talcum powder and barium sulfate in a mass ratio of 3:2.

[0022] A method for preparing double-sided matte polypropylene synthetic paper comprises the following steps:

[0023] B1: Extruding the outer layer raw material, the middle layer raw material and the inner layer raw material through an extruder respectively;

[0024] B2: The raw materials of each layer extruded by the extruder are extruded through a T-type die, and then stretched longitudinally and transversely, followed by cooling, corona treatment, and trimming.

[0025] Among them, the extrusion temperature of the outer layer raw material and the inner surface layer raw material is 225°C, and the extrusion temperature of the middle layer raw material is 245°C; the preheating section temperature of longitudinal stretching is 130°C, the stretching section temperature is 142°C, the setting section temperature is 145°C, the longitudinal stretching ratio is 4.9, the preheating section temperature of transverse stretching is 167°C, the stretching section temperature is 155°C, the setting section temperature is 171°C, the transverse stretching ratio is 9 times, and the corona is 34.

[0026] Application of double-sided matte polypropylene synthetic paper in TPU hot melt adhesive.

[0027] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0028] (1) The water repellent prepared by the present invention can significantly improve the waterproof performance of polypropylene synthetic paper through the synergistic effect of perfluoro chains, polyester segments and imidazole groups.

[0029] (2) The lubricant prepared by the present invention reduces the surface friction coefficient through the long-chain alkyl hydrophobic layer. The synergistic effect of the epoxy soybean oil skeleton and amino-modified silica makes the lubricant uniformly dispersed, reducing the risk of migration. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0031] Example 1 Preparation of water repellent:

[0032] S1: Under nitrogen protection, 1200g DMF, 0.1mol pentaerythritol and 1.2mol 3,6-dimethyl-1,4-dioxane-2,5-dione were added to the reactor, stirred and mixed, heated to 130°C, stirred for 15min, then 10g of catalyst stannous octoate was added, reacted for 20h, cooled to room temperature, and distilled under reduced pressure at 60°C for 2h to obtain a crude product. The crude product was added to 500ml chloroform and stirred, then 500ml cold methanol was added, allowed to stand to precipitate, filtered, and then washed three times with methanol (500ml each time), and dried under vacuum at 60°C for 5h to obtain a four-arm compound with a number average molecular weight of 1762; the reaction equation is as follows:

[0033] .

[0034] S2: Under nitrogen protection, 1000 ml of N,N-dimethylacetamide, 0.1 mol of the four-arm compound, and 50 g of anhydrous K2CO3 were added to the reactor, stirred and mixed, and the temperature was raised to 80°C. Then, 0.2 mol of 5-(4-bromophenyl)-1-methylimidazole was added in batches (0.02 mol per batch, with a batch interval of 5 min). After reacting for 10 hours, the temperature was lowered to room temperature, and 100 ml of anhydrous ethanol and 800 ml of deionized water were slowly added. The mixture was stirred to precipitate, filtered, and then washed three times with deionized water (500 ml of deionized water each time). Then, 500 ml of anhydrous ethanol was added for recrystallization, and the mixture was dried under vacuum at 70°C for 2 hours to obtain the imidazole-modified four-arm compound; the number average molecular weight was 2058; the reaction equation is shown as follows:

[0035] .

[0036] S3: Under nitrogen protection, 1200g DMF and 0.1mol perfluorododecanoic acid were added to the reactor, stirred and mixed, heated to 60°C, stirred for 30min, then 0.1mol imidazole-modified four-arm compound and 15g p-toluenesulfonic acid were added, heated to 80°C for reaction for 6h, cooled to room temperature, saturated sodium bicarbonate solution was slowly added to adjust the pH to neutral, 1000ml toluene was added, stirred, precipitated, filtered, washed three times with toluene (300ml each time), and vacuum dried at 70°C for 10h to obtain a water repellent; the number average molecular weight was 2595; the reaction equation is as follows:

[0037] .

[0038] Example 2 Preparation of water repellent:

[0039] S1: Under nitrogen protection, 1200g DMF, 0.1mol pentaerythritol and 1.6mol 3,6-dimethyl-1,4-dioxane-2,5-dione were added to the reactor, stirred and mixed, heated to 130°C, stirred for 15min, and then 10g of catalyst stannous octoate was added. After reacting for 24h, the mixture was cooled to room temperature and distilled under reduced pressure at 60°C for 2h to obtain a crude product. The crude product was added to 500ml chloroform and stirred, and then 500ml cold methanol was added. The mixture was allowed to stand for precipitation, filtered, and washed three times with methanol (500ml each time). The mixture was dried under vacuum at 60°C for 5h to obtain a four-arm compound with a number average molecular weight of 2318;

[0040] S2: Under nitrogen protection, 1000 ml of N,N-dimethylacetamide, 0.1 mol of the four-arm compound, and 50 g of anhydrous K2CO3 were added to the reactor, stirred and mixed, and the temperature was raised to 85°C. Then, 0.21 mol of 5-(4-bromophenyl)-1-methylimidazole was added in batches (0.03 mol per batch, with a batch interval of 5 min). After reacting for 9 hours, the temperature was cooled to room temperature, and 100 ml of anhydrous ethanol and 800 ml of deionized water were slowly added. The mixture was stirred and the precipitate was precipitated. The mixture was filtered and washed three times with deionized water (500 ml of deionized water each time). Then, 500 ml of anhydrous ethanol was added for recrystallization, and the mixture was dried under vacuum at 70°C for 2 hours to obtain the imidazole-modified four-arm compound; the number average molecular weight was 2630;

[0041] S3: Under nitrogen protection, add 1200g DMF and 0.11mol perfluorododecanoic acid to the reactor, stir and mix, heat to 60℃, stir for 30min, then add 0.1mol imidazole-modified four-arm compound and 15g p-toluenesulfonic acid, heat to 90℃ and react for 5h, then cool to room temperature, slowly add saturated sodium bicarbonate solution to adjust the pH to neutral, add 1000ml toluene, stir, precipitate, filter, wash three times with toluene (300ml each time), and vacuum dry at 70℃ for 10h to obtain a water repellent; the number average molecular weight is 3227.

[0042] Example 3 Preparation of water repellent:

[0043] S1: Under nitrogen protection, 1200g DMF, 0.1mol pentaerythritol and 2mol 3,6-dimethyl-1,4-dioxane-2,5-dione were added to the reactor, stirred and mixed, heated to 130°C, stirred for 15min, then 10g stannous octoate catalyst was added, reacted for 26h, cooled to room temperature, and distilled under reduced pressure at 60°C for 2h to obtain a crude product. The crude product was added to 500ml chloroform and stirred, then 500ml cold methanol was added, allowed to stand to precipitate, filtered, and washed three times with methanol (500ml each time), and dried under vacuum at 60°C for 5h to obtain a four-arm compound; the number average molecular weight was 2984;

[0044] S2: Under nitrogen protection, 1000 ml of N,N-dimethylacetamide, 0.1 mol of the four-arm compound, and 50 g of anhydrous K2CO3 were added to the reactor, stirred and mixed, and the temperature was raised to 90°C. Then, 0.22 mol of 5-(4-bromophenyl)-1-methylimidazole was added in batches (0.02 mol per batch, with a batch interval of 5 min). After reacting for 8 hours, the temperature was cooled to room temperature, and 100 ml of anhydrous ethanol and 800 ml of deionized water were slowly added. The mixture was stirred, the precipitate was precipitated, filtered, and then washed three times with deionized water (500 ml of deionized water each time). Then, 500 ml of anhydrous ethanol was added for recrystallization, and the mixture was dried under vacuum at 70°C for 2 hours to obtain the imidazole-modified four-arm compound; the number average molecular weight was 3312;

[0045] S3: Under nitrogen protection, add 1200g DMF and 0.12mol perfluorododecanoic acid to the reactor, stir and mix, heat to 60℃, stir for 30min, then add 0.1mol imidazole-modified four-arm compound and 15g p-toluenesulfonic acid, heat to 100℃ and react for 4h, then cool to room temperature, slowly add saturated sodium bicarbonate solution to adjust the pH to neutral, add 1000ml toluene, stir, precipitate, filter, wash three times with toluene (300ml each time), and dry in vacuo at 70℃ for 10h to obtain a water repellent; the number average molecular weight is 3938.

[0046] Example 4 Preparation of lubricant:

[0047] A1: Under nitrogen, 1000 ml of DMF and 0.1 mol of octadecylamine were added to a reactor, stirred and mixed, and 0.4 mol of epoxidized soybean oil was added. The temperature was raised to 60°C and the reaction was allowed to proceed for 6 hours. The mixture was cooled to room temperature, and 800 ml of deionized water was slowly added. The mixture was stirred, allowed to settle, and filtered. The mixture was washed with 400 ml of deionized water and dried under vacuum at 70°C for 12 hours to obtain long-chain alkyl-modified soybean oil. In this reaction, some epoxy groups in the epoxidized soybean oil reacted with amino groups in the octadecylamine.

[0048] A2: Under nitrogen protection, 1500 ml of DMF and 100 g of amino-modified silica were added to a reactor and stirred to mix. 150 g of long-chain alkyl-modified soybean oil was added, and the temperature was raised to 60°C. The reaction was allowed to proceed for 6 hours. After cooling to room temperature, 800 ml of deionized water was slowly added. The mixture was stirred, allowed to settle, and filtered. The mixture was washed with 400 ml of deionized water and dried under vacuum at 70°C for 12 hours to obtain a lubricant. During this reaction, the remaining epoxy groups in the long-chain alkyl-modified soybean oil reacted with the amino groups in the amino-modified silica.

[0049] Example 5

[0050] A double-sided matte polypropylene synthetic paper with a thickness of 0.20 mm, an outer layer and an inner layer with a thickness of 0.06 mm, and a middle layer with a thickness of 0.08 mm;

[0051] The raw material composition of the outer layer is: polypropylene: 400g, antioxidant (antioxidant 702): 4g, calcium carbonate: 300g, titanium dioxide 20g, water repellent (prepared in Example 1) 30g, matte flour (6g talc, 4g barium sulfate) 10g, slip agent (prepared in Example 4) 5g, antistatic agent (AS11N antistatic agent) 20g;

[0052] The raw material composition of the middle layer is: polypropylene: 300g, calcium carbonate: 20g, titanium dioxide: 10g;

[0053] The raw materials and proportions of the inner surface layer are the same as those of the outer surface layer.

[0054] Example 6

[0055] A double-sided matte polypropylene synthetic paper with a thickness of 0.20 mm, with the outer and inner layers both having a thickness of 0.06 mm and the middle layer having a thickness of 0.08 mm;

[0056] The raw material composition of the outer layer is: polypropylene: 450g, antioxidant (antioxidant 1010): 6g, calcium carbonate: 320g, titanium dioxide 25g, water repellent (prepared in Example 2) 40g, matte flour (9g talc, 6g barium sulfate) 15g, slip agent (prepared in Example 4) 8g, antistatic agent (Armostat 400 antistatic agent) 30g;

[0057] The raw material composition of the middle layer is: polypropylene: 400g, calcium carbonate: 40g, titanium dioxide: 15g;

[0058] The raw materials and proportions of the inner surface layer are the same as those of the outer surface layer.

[0059] Example 7

[0060] A double-sided matte polypropylene synthetic paper with a thickness of 0.20 mm, with the outer and inner layers both having a thickness of 0.06 mm and the middle layer having a thickness of 0.08 mm;

[0061] The raw material composition of the outer layer is: polypropylene: 500g, antioxidant (antioxidant 1076): 8g, calcium carbonate: 350g, titanium dioxide 30g, water repellent (prepared in Example 3) 50g, matte flour (12g talc, 8g barium sulfate) 20g, slip agent (prepared in Example 4) 10g, antistatic agent (Armostat400 antistatic agent) 40g;

[0062] The raw material composition of the middle layer is: polypropylene: 500g, calcium carbonate: 60g, titanium dioxide: 20g;

[0063] The raw materials and proportions of the inner surface layer are the same as those of the outer surface layer.

[0064] Comparative Example 1

[0065] The raw material composition of the double-sided matte polypropylene synthetic paper is basically the same as that of Example 6, except that the water repellent added to the outer and inner surface layers is replaced by an equal weight of a water repellent prepared by the following method:

[0066] The preparation method of the water repellent is basically the same as that of Example 2, except that the amount of 5-(4-bromophenyl)-1-methylimidazole added in step S2 is increased to 0.3 mol.

[0067] Comparative Example 2

[0068] The raw material composition of the double-sided matte polypropylene synthetic paper is basically the same as that of Example 6, except that the water repellent added to the outer and inner surface layers is replaced by an equal weight of a water repellent prepared by the following method:

[0069] The preparation method of the water repellent is basically the same as that of Example 2, except that the 5-(4-bromophenyl)-1-methylimidazole in step S2 is replaced by an equimolar amount of 1-(4-bromophenyl)-3-methyl-1H-pyrazole-5-amine.

[0070] Comparative Example 3

[0071] The raw material composition of the double-sided matte polypropylene synthetic paper is basically the same as that of Example 6, except that the water repellent added to the outer and inner surface layers is replaced by an equal weight of a water repellent prepared by the following method:

[0072] The preparation method of the water repellent is substantially the same as that of Example 2, except that the perfluorododecanoic acid in step S3 is replaced by an equimolar amount of perfluorooctadecanoic acid.

[0073] Comparative Example 4

[0074] The raw material composition of the double-sided matte polypropylene synthetic paper is basically the same as that of Example 6, except that the water repellent added to the outer and inner surface layers is replaced by an equal weight of a water repellent prepared by the following method:

[0075] The preparation method of the water repellent is basically the same as that of Example 2, except that the amount of perfluorododecanoic acid added in step S3 is increased to 0.2 mol.

[0076] Comparative Example 5

[0077] The raw material composition of the double-sided matte polypropylene synthetic paper is basically the same as that of Example 6, except that the lubricant added to the middle layer is replaced by an equal weight of a lubricant prepared by the following method:

[0078] The preparation method of the lubricant is basically the same as that of Example 4, except that the octadecylamine in step A1 is replaced by an equal weight of dodecylamine.

[0079] Comparative Example 6

[0080] The raw material composition of the double-sided matte polypropylene synthetic paper is basically the same as that of Example 6, except that the lubricant added to the middle layer is replaced by 6g of modified lubricant and 2g of amino-modified silica.

[0081] The modified slip agent is prepared by the following method:

[0082] Under nitrogen protection, 1000 ml of DMF and 0.1 mol of octadecylamine were added to the reactor, stirred and mixed, 0.4 mol of epoxidized soybean oil was added, the temperature was raised to 60 ° C, the reaction was carried out for 6 hours, and the mixture was cooled to room temperature. 500 ml of deionized water was added and the solid was filtered to obtain a solid. The solid was washed with 600 ml of deionized water and dried in vacuo at 70 ° C for 24 hours to generate a modified lubricant.

[0083] The double-sided matte polypropylene synthetic paper of Examples 5-7 and Comparative Examples 1-6 was prepared by the following process:

[0084] B1: Extruding the outer layer raw material, the middle layer raw material and the inner layer raw material through an extruder respectively;

[0085] B2: The raw materials of each layer extruded by the extruder are extruded through a T-type die, and then stretched longitudinally and transversely, followed by cooling, corona treatment, and trimming.

[0086] Among them, the extrusion temperature of the outer layer raw material and the inner surface layer raw material is 225°C, and the extrusion temperature of the middle layer raw material is 245°C; the preheating section temperature of longitudinal stretching is 130°C, the stretching section temperature is 142°C, the setting section temperature is 145°C, the longitudinal stretching ratio is 4.9, the preheating section temperature of transverse stretching is 167°C, the stretching section temperature is 155°C, the setting section temperature is 171°C, the transverse stretching ratio is 9 times, and the corona is 34.

[0087] The amino-modified silica used in the examples and comparative examples of the present application was prepared by the following method:

[0088] 100 mL of anhydrous ethanol, 10 mL of aqueous ammonia, and 20 mL of deionized water were mixed and stirred at room temperature for 10 minutes. 10 mL of LTEOS was slowly added dropwise for 10 minutes, and the mixture was stirred for 6 hours to form a milky white SiO2 sol. After the reaction, the precipitate was collected by centrifugation (8000 rpm, 10 minutes), washed three times with ethanol and deionized water (50 mL of ethanol and 50 mL of deionized water each time), and dried in a vacuum at 60°C for 6 hours to obtain SiO2 microspheres. 1 g of dried SiO2 microspheres was dispersed in 50 mL of anhydrous ethanol and sonicated for 30 minutes. 5 mL of APTES was added and the mixture was refluxed under nitrogen for 12 hours. After the reaction, the product was collected by centrifugation, washed with deionized water until neutral, and dried in a vacuum at 60°C for 12 hours to obtain amino-modified silica.

[0089] The polypropylene used in the examples and comparative examples of the present application is CJS-700 homopolymer polypropylene produced by China Petrochemical Corporation; the brand of titanium dioxide is DuPont R-706; the molecular formula of epoxidized soybean oil is: 57 H 98 O 12 The talcum powder model is BHS-818T, produced by Quanzhou Xufeng Powder Raw Materials Co., Ltd.

[0090] The double-sided matte polypropylene synthetic paper prepared in Examples 5-7 and Comparative Examples 1-6 was subjected to a water absorption test according to GB / T 1034-2008 "Determination of water absorption of plastics" (Method 2: Determination of water absorption in boiling water); an antibacterial test was carried out using Escherichia coli and Staphylococcus aureus as the test species according to GB / T31402-2015 "Test method for antibacterial properties of plastic surfaces"; and a friction coefficient test was carried out according to GB / T 10006-2021 "Determination of friction coefficient of plastic films and sheets". The test results are shown in Table 1.

[0091] Table 1 Synthetic paper performance test table

[0092]

[0093] It can be seen from Examples 5, 6 and 7 in Table 1 that the double-sided matte polypropylene synthetic paper prepared by the present invention has excellent waterproof and antibacterial properties.

[0094] The water repellent prepared by this invention has a four-arm structure. The long-chain fluorinated groups within the perfluorinated chain segments have extremely low surface energy. Within the polypropylene matrix, they spontaneously migrate to the surface of the material, forming a hydrophobic barrier. This arrangement significantly reduces surface wettability and reduces water adsorption. The introduced imidazole groups possess antimicrobial properties. The nitrogen atoms of the imidazole rings can bind to essential metal ions required by microorganisms, depriving them of the ability to participate in the activity of metabolic enzymes (such as peroxidases and hydrolases). The flexible segments (polyester segments) in the water repellent possess low surface energy. During melt blending and processing, they facilitate migration and accumulation on the surface of PP synthetic paper, forming a uniform, dense hydrophobic barrier. This reduces the surface tension of the material, making it difficult for water droplets to penetrate and spread, thereby achieving excellent water repellency. However, when the number of perfluorinated chain arms grafted in the water repellent is larger or the fluorine chain is longer, the compatibility with polypropylene will be affected. The van der Waals force and dipole interaction between the perfluorinated chain segments will be significantly enhanced, resulting in entanglement or agglomeration between the molecular chains, hindering the fluorocarbon chains from forming a regular vertical orientation on the PP surface, thereby reducing the hydrophobic performance.

[0095] The present invention achieves the matte properties of the PP synthetic paper surface through matte flour and calcium carbonate. The prepared lubricant contains octadecyl chain segments. Its long-chain alkyl-modified soybean oil structure easily migrates to the surface to form a lubricating layer under high-temperature processing (withstands up to 245°C) and high-ratio stretching (transverse stretching ratio of 9 times), thereby reducing the friction coefficient and ensuring the smoothness of the material surface. At the same time, the grafted amino-modified silica particles increase the surface micro-roughness, synergistically working with the matte filler to enhance the matte effect and maintain uniformity.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in this field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A double-sided matte polypropylene synthetic paper, consisting of an outer layer, an intermediate layer and an inner layer, characterized in that: The outer layer comprises the following raw materials in parts by weight: polypropylene: 40-50 parts, antioxidant: 0.4-0.8 parts, calcium carbonate: 30-35 parts, titanium dioxide: 2-3 parts, water repellent: 3-5 parts, matte flour: 1-2 parts, slip agent: 0.5-1 parts, antistatic agent: 2-4 parts; The middle layer comprises the following raw materials in parts by weight: polypropylene: 30-50 parts, calcium carbonate: 2-6 parts, titanium dioxide: 1-2 parts; The material and quantity of the inner surface layer are the same as those of the outer surface layer; The water repellent is prepared by the following method: S1: Pentaerythritol reacts with 3,6-dimethyl-1,4-dioxane-2,5-dione under the catalysis of stannous octoate to form a four-arm compound; S2: The four-arm compound reacts with 5-(4-bromophenyl)-1-methylimidazole to form an imidazole-modified four-arm compound; S3: The imidazole-modified four-arm compound reacts with perfluorododecanoic acid to form a water repellent; The molar ratio of pentaerythritol to 3,6-dimethyl-1,4-dioxane-2,5-dione in step S1 is 1:(12-20); The molar ratio of the four-arm compound to 5-(4-bromophenyl)-1-methylimidazole in step S2 is 1:(2-2.2); The molar ratio of the imidazole-modified four-arm compound to perfluorododecanoic acid in step S3 is 1:(1-1.2); The lubricant is prepared by the following method: A1: Epoxidized soybean oil reacts with octadecylamine to produce long-chain alkyl-modified soybean oil; A2: Long-chain alkyl-modified soybean oil reacts with amino-modified silica to form a lubricant; The molar ratio of the epoxy soybean oil to octadecylamine in step A1 is 1:4; the mass ratio of the long-chain alkyl-modified soybean oil to amino-modified silica in step A2 is 1:1.

5.

2. The double-sided matte polypropylene synthetic paper according to claim 1, characterized in that: The antioxidant is one of antioxidant 702, antioxidant 1010, and antioxidant 1076; the antistatic agent is one of AS11N antistatic agent and Armostat400 antistatic agent.

3. The double-sided matte polypropylene synthetic paper according to claim 1, characterized in that: The mist flour is prepared by mixing talcum powder and barium sulfate in a mass ratio of 3:

2.

4. A method for preparing double-sided matte polypropylene synthetic paper according to any one of claims 1 to 3, characterized in that: The following steps are involved: B1: Extruding the outer layer raw material, the middle layer raw material and the inner layer raw material through an extruder respectively; B2: The raw materials of each layer extruded by the extruder are extruded through a T-type die, and then stretched longitudinally and transversely, followed by cooling, corona treatment, and trimming. Among them, the extrusion temperature of the outer layer raw material and the inner surface layer raw material is 225°C, and the extrusion temperature of the middle layer raw material is 245°C; the preheating section temperature of longitudinal stretching is 130°C, the stretching section temperature is 142°C, the setting section temperature is 145°C, the longitudinal stretching ratio is 4.9, the preheating section temperature of transverse stretching is 167°C, the stretching section temperature is 155°C, the setting section temperature is 171°C, the transverse stretching ratio is 9 times, and the corona is 34.

5. Use of the double-sided matte polypropylene synthetic paper according to any one of claims 1 to 3 in TPU hot melt adhesive.

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