Preparation process of matt PE film for soft cotton towel packaging

Abstract

The invention relates to the technical field of matt films, and discloses a preparation process of a matt PE film for soft cotton towel packaging, which comprises the following steps: synthesizing a four-long-chain alkylated dibutyl phosphate monomer by using dibutyl phosphite, 2-(oxazolidine-3-yl) ethanol and di (hydrogenated tallow) phthalic acid amide as raw materials, modifying the four-long-chain alkylated dibutyl phosphate monomer on the surface of SiO2 through a covalent grafting method, and preparing the matt PE film for soft cotton towel packaging. A solvent-free nano SiO2 fluid with a core-shell structure is obtained; the preparation method comprises the following steps: filling a polyethylene and polypropylene mixed resin matrix with a solvent-free nano SiO2 fluid, and mixing to form a homogeneous system, so as to prepare extinction master batch; the matt PE film for packaging the soft cotton towels is prepared by taking the matt master batch as an outer-layer raw material, taking high-density polyethylene resin as a middle-layer raw material and taking metallocene polyethylene resin as an inner-layer raw material and adopting a three-layer co-extrusion blow molding film forming process. The matt PE film researched and developed by the invention shows very excellent matt performance while the tear resistance is slightly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of matt films, in particular to a preparation process of a matt PE film for packaging cotton towels. Background Art

[0002] Matt film is a packaging film with a surface similar to paper, very low gloss, high haze, and diffuse reflective matte effect. The surface reflects weak and soft light, with a surface gloss less than 15% and a haze generally above 70%. It has many advantages such as comfortable hand feel, soft and delicate matte effect in appearance, and realistic color reproduction when printed. It has become an important functional material to enhance the texture of cotton wipes packaging.

[0003] Almost all plastics (such as PA, PET, PC, PE and PP) can be used to produce matte films, but the specific technical means to achieve the matte effect are different. At present, there are mainly the following ways to achieve the matte effect: adding light-absorbing substances, such as graphite; adding matting agents, such as SiO 2 ; Use secondary processing such as roller embossing, solvent and chemical etching; The polymer itself is matte, such as polyvinyl chloride PVC and polylactic acid PLA. Among them, adding SiO to PE blown film 2 The use of matting agents to prepare matte PE film is a technically feasible solution that is in line with the development trend of the packaging film industry. Summary of the invention

[0004] Based on the actual needs of the development of the packaging film industry and the current status of the existing technology, the present invention develops a PE film with superior performance, more suitable cost and matting function for use in the packaging of cotton soft towels.

[0005] A preparation process of a matte PE film for packaging cotton wipes, comprising the following steps: Step 1: Using dibutyl phosphite, 2-(oxazolidin-3-yl)ethanol and di(hydrogenated tallow)phthalic acid amide as raw materials, a tetra-long-chain alkylated dibutyl phosphate monomer was synthesized and modified on SiO by covalent grafting. 2 The surface of the solvent-free nano-SiO 2 fluid; Step 2: Solvent-free nano-SiO 2 The fluid is filled into the polyethylene and polypropylene mixed resin matrix to form a homogeneous system to obtain a matte masterbatch; wherein the matte masterbatch contains solvent-free nano-SiO 2 The content of the fluid is 5-20wt%; Step 3: Using matte masterbatch as the outer layer raw material, high-density polyethylene resin as the middle layer raw material, and metallocene polyethylene resin as the inner layer raw material, a three-layer co-extrusion blow molding film-forming process is adopted to prepare a matte PE film for cotton soft towel packaging.

[0006] Preferably, the preparation method of the tetra-long-chain alkylated dibutyl phosphate monomer is: The PH bond of dibutyl phosphite undergoes an epoxy ring-opening reaction with 2-(oxazolidin-3-yl)ethanol to generate dibutyl dihydroxyphosphate monomer; The tetra-long-chain alkylated dibutyl phosphate monomer is prepared by esterification reaction between the hydroxyl functional group of dihydroxy dibutyl phosphate monomer and the carboxyl functional group of di(hydrogenated tallow) phthalic acid amide.

[0007] Preferably, the solvent-free nano-SiO 2 The preparation method of the fluid is as follows: under acidic conditions, the phosphorus hydroxyl functional group obtained by hydrolyzing the tetra-long chain alkylated dibutyl phosphate monomer reacts with the hydroxylated SiO 2 The hydroxyl functional groups on the surface undergo dehydration condensation reaction, and the tetra-long-chain alkylated dibutyl phosphate monomer is modified on the SiO 2 Surface, prepared solvent-free nano-SiO 2 fluid.

[0008] Preferably, the solvent-free nano-SiO 2 Four long-chain alkylated dibutyl phosphate monomers and hydroxylated SiO in fluid 2 The mass ratio is 1:(3-10).

[0009] Preferably, the formula of the matte masterbatch is: 70-90wt% low-density polyethylene resin, 5-15wt% polypropylene resin and 5-20wt% solvent-free nano-SiO 2 fluid.

[0010] Preferably, the product structure of the matt PE film for packaging cotton wipes is: The first layer: a matte layer prepared with matte masterbatch as raw material, the amount of this layer is 30-45 parts by weight; The second layer: a support layer made of high-density polyethylene resin, the amount of which is 30-45 parts by weight; The third layer: a heat-sealing layer made of metallocene polyethylene resin, the amount of which is 10-40 parts by weight.

[0011] Preferably, the preparation method of the matt PE film for cotton wipe packaging is: the ingredients are prepared according to the raw material formula of the matt PE film for cotton wipe packaging, and the raw materials of each layer are respectively put into the hoppers of three screw extruders of the three-layer co-extrusion film blow molding unit, after stirring and mixing, the molten resin is converged at the head of the machine through a diverter, and is extruded and blow-molded through a die head, the blowing ratio is controlled at 2.5-3.0, cooled, and rolled up to prepare the matt PE film for cotton wipe packaging.

[0012] Preferably, the process parameters of the screw extruder corresponding to the matt layer are set as follows: the temperatures of zones 1-3 are 140-155°C, 160-180°C, 185-195°C, respectively; the flow channel temperature is 180-190°C; and the rotation speed is 50-70r / min.

[0013] The matte PE film for cotton soft towel packaging prepared according to the above process has a thickness of 50-150 μm.

[0014] Beneficial effects: The present invention develops a tetra-long-chain alkylated dibutyl phosphate monomer, and grafts the alkyl long chain onto nano-SiO by a covalent grafting method. 2 surface, a new solvent-free nano-SiO 2 Fluid, the solvent-free nano-SiO 2 The fluid is filled into a mixed resin matrix composed of polyethylene and polypropylene to form a homogeneous system to obtain a matte masterbatch; The experimental results show that solvent-free nano-SiO 2 The development of this technical means of fluid eliminates the nano-SiO 2 The adverse effect of matting agent on the tear strength of PE film; The matte masterbatch is used as the raw material of the outer matte layer, the high-density polyethylene resin is used as the raw material of the middle layer support layer, and the metallocene polyethylene resin is used as the raw material of the inner layer heat sealing layer. The matte PE film is prepared by a three-layer co-extrusion blow molding film-forming process. The experimental results show that the matte PE film prepared by the present invention has very excellent matte performance while its tear resistance is only slightly reduced, and can be used as a matte material for improving the texture of cotton towel packaging. DETAILED DESCRIPTION

[0015] The main raw materials used in the present invention are as follows: Low density polyethylene resin (LDPE), brand LD 150DW, melt mass flow rate (MFR) is 0.3g / 10min (220℃, 2kg); Polypropylene resin (PP), brand R520Y, MFR 1.8g / 10min (230℃, 2kg); Hydroxylated silica nanopowder, particle size 10-20nm; High-density polyethylene resin (HDPE), brand FB5600; Metallocene polyethylene resin (m-LLDPE), brand name SP4020. Experimental example:

[0016] For adding SiO 2Matting agent will cause the film's tear strength to seriously decrease. The present invention has developed a solvent-free nano-SiO 2 Fluid, using solvent-free nano-SiO 2 The fluid is mixed with the polyolefin resin matrix to form a matte masterbatch. In this process, solvent-free nano-SiO 2 The fluid migrates into the polyolefin resin matrix and solves the SiO 2 While solving the problem of nanoparticle agglomeration, it can effectively improve the interface compatibility of the matte material, thereby overcoming the SiO 2 The technical defect that the matting agent causes the tear strength of the PE film to be seriously reduced; Using dibutyl phosphite, 2-(oxazolidin-3-yl)ethanol and di(hydrogenated tallow)phthalic acid amide as raw materials, a tetra-long-chain alkylated dibutyl phosphate monomer was designed and synthesized. 2 The surface of the solvent-free nano-SiO 2 fluid; Solvent-free nano-SiO 2 The steps for preparing the fluid are as follows: Step 1: Prepare tetra-long-chain alkylated dibutyl phosphate monomer, the preparation method thereof is as follows: First, the PH bond of dibutyl phosphite undergoes a ring-opening reaction with 2-(oxazolidin-3-yl)ethanol to generate dibutyl dihydroxyphosphate monomer, whose chemical structure is: ; Then, the hydroxyl functional group of the dihydroxy dibutyl phosphate monomer and the carboxyl functional group of di(hydrogenated tallow) phthalic acid amide are subjected to an esterification reaction to prepare a tetra-long-chain alkylated dibutyl phosphate monomer, the chemical structure of which is: ; The specific experimental steps for preparing tetra-long-chain alkylated dibutyl phosphate monomers are: First, 1.9 g of dibutyl phosphite, 1.2 g of 2-(oxazolidin-3-yl)ethanol and 50 mL of methanol were added to a three-necked flask, and the temperature was raised to 70°C for reflux reaction for 6 h under mechanical stirring, and the solvent was removed by rotary evaporation, and vacuum drying was performed to obtain a dihydroxy dibutyl phosphate monomer; then, 1.5 g of dihydroxy dibutyl phosphate monomer and 30 mL of N,N-dimethylformamide were added to the three-necked flask, and the mixture was stirred at room temperature until all dissolved, and 50 mL of an N,N-dimethylformamide solution containing 6.7 g of di(hydrogenated tallow)phthalic acid amide and 5 drops of concentrated sulfuric acid were added in sequence, and the solvent was removed by rotary evaporation, and the mixture was washed with ethanol and vacuum dried to obtain a tetra-long-chain alkylated dibutyl phosphate monomer; The nuclear magnetic resonance hydrogen spectrum characterization results of the tetra-long-chain alkylated dibutyl phosphate monomer are as follows: 1 H NMR (CDCl3 ,400MHz) δ: 0.86-0.90 (t, 12H), 0.96-1.00 (t, 6H), 1.21-1.33 (m, 120H), 1.40-1.48 (m, 4H), 1.62-1.69 (m, 8H), 1.81-1.88 (m, 4 H), 2.85-2.89(t, 4H), 3.03-3.18(m, 2H), 3.43-3.47(t, 8H), 3.89-3.94(m, 4H), 4.30-4.34(t, 4H), 7.27-7.92(m, 8H); Step 2: Preparation of solvent-free nano-SiO 2 The preparation method of the fluid is as follows: under acidic conditions, the phosphorus hydroxyl functional group obtained by hydrolyzing the tetra-long chain alkylated dibutyl phosphate monomer is reacted with the hydroxylated SiO 2 The hydroxyl functional groups on the surface undergo dehydration condensation reaction, and the tetra-long-chain alkylated dibutyl phosphate monomer is modified on the SiO 2 surface, and the alkyl long chains on SiO 2 A corona layer is formed on the surface to prepare solvent-free nano-SiO with a core-shell structure. 2 fluid; The core layer is SiO surrounded by four long-chain alkylated dibutyl phosphate monomers. 2 Nanoparticles, the shell is composed of long alkyl chains, which is equivalent to the "solvent", SiO 2 Nanoparticles provide mobility; Preparation of solvent-free nano-SiO 2 The specific experimental steps of the fluid are as follows: 1g of tetra-long-chain alkylated dibutyl phosphate monomer, 15mL of ethanol and 5mL of deionized water are added to a beaker, the solution pH is adjusted to 4 with 0.1mol / L hydrochloric acid, and the solution is stirred and dispersed at room temperature for 30min, 100mL of a mixed solution containing 8g of hydroxylated silica nanopowder (the mixed solution consists of 3 parts by volume of ethanol and 1 part by volume of deionized water) is added, ultrasonic mixing is performed for 5min, the temperature is raised to 60℃ and stirred for reaction for 4h, centrifuged, and washed repeatedly by centrifugation with anhydrous ethanol and deionized water, and dried under vacuum at 80℃ for 2h to obtain solvent-free nano-SiO 2 fluid. Embodiment 1:

[0017] The matte masterbatch I was prepared with the following formula: 85wt% low-density polyethylene resin, 10wt% polypropylene resin and 5wt% solvent-free nano-SiO 2 The preparation method of the fluid is as follows: the ingredients are prepared according to the formula of the matte masterbatch I, the formula raw materials are added into a high-speed mixer and mixed evenly, extruded into granules by a twin-screw extruder, and vacuum dried at 80° C. for 6 hours to obtain the matte masterbatch I; Among them, the process parameters of the twin-screw extruder are set as follows: the temperatures of zones 1-6 are 165°C, 170°C, 175°C, 180°C, 180°C, and 190°C, respectively, and the rotation speed is 300r / min. Embodiment 2:

[0018] The matte masterbatch II was prepared with the following formula: 80wt% low-density polyethylene resin, 10wt% polypropylene resin and 10wt% solvent-free nano-SiO 2 The preparation method of the fluid is the same as that of the matte masterbatch I. Embodiment three:

[0019] The matte masterbatch III was prepared with the formula of 70wt% low-density polyethylene resin, 10wt% polypropylene resin and 20wt% solvent-free nano-SiO 2 The preparation method of the fluid is the same as that of the matte masterbatch I. Embodiment 4:

[0020] A matte PE film I for packaging cotton soft towels, the product structure of which is: The first layer: a matte layer prepared with matte masterbatch I as raw material, the amount of this layer is 40 parts by weight; The second layer: a support layer made of high-density polyethylene resin, the amount of which is 40 parts by weight; The third layer: a heat-sealing layer prepared from metallocene polyethylene resin as raw material, the amount of this layer is 20 parts by weight. Embodiment five:

[0021] A preparation process of matt PE film I for cotton soft towel packaging, the specific preparation steps are as follows: According to the raw material formula of matt PE film I for cotton soft towel packaging, the raw materials of each layer are respectively put into the hoppers of three screw extruders of the three-layer co-extrusion film blow molding unit, and after stirring and mixing, the molten resin is merged at the head of the die through a diverter, and extruded and blow-molded through a die head, and the blow-up ratio is controlled at 2.9, cooled and rolled, to prepare matt PE film I for cotton soft towel packaging with a thickness of 100 μm; The process parameters of the screw extruder corresponding to the matte layer are set as follows: the temperatures of zones 1-3 are 150°C, 170°C, and 190°C, respectively, the flow channel temperature is 185°C, and the rotation speed is 60r / min; The process parameters of the screw extruder corresponding to the support layer were set as follows: the temperatures of zones 1-3 were 130°C, 150°C, and 175°C, respectively, the flow channel temperature was 170°C, and the rotation speed was 30 r / min; The process parameters of the screw extruder corresponding to the heat sealing layer are set as follows: the temperatures of zones 1-3 are 120°C, 150°C, and 170°C, respectively, the flow channel temperature is 160°C, and the rotation speed is 30 r / min. Embodiment six:

[0022] A matte PE film II for packaging cotton soft towels, the product structure of which is different from the matte PE film I for packaging cotton soft towels in Example 4 only in that the matte masterbatch II is used to replace the matte masterbatch I; The preparation process of the matt PE film II for cotton soft towel packaging is the same as the preparation process of the matt PE film I for cotton soft towel packaging in Example 5. Embodiment seven:

[0023] A matte PE film III for cotton soft towel packaging, the product structure of which is different from the matte PE film I for cotton soft towel packaging in Example 4 only in that the matte masterbatch III is used to replace the matte masterbatch I; The preparation process of the matt PE film III for cotton soft towel packaging is the same as the preparation process of the matt PE film I for cotton soft towel packaging in Example 5. Comparative Example 1:

[0024] Preparation of PE film a: Compared with matte PE film Ⅰ for cotton soft towel packaging, the only difference is that the matte masterbatch Ⅰ is replaced by the blended masterbatch; The formula of the blended masterbatch is: 80wt% low-density polyethylene resin, 10wt% polypropylene resin and 10wt% hydroxylated silica nanopowder, and its preparation method is the same as that of the matte masterbatch I. Comparative Example 2:

[0025] Preparation of PE film b: Compared with the matte PE film Ⅰ for cotton wipes packaging, the only difference is that low-density polyethylene resin is used to replace the matte masterbatch Ⅰ. Performance Test:

[0026] The performance of the matte PE film samples for cotton wipe packaging was tested, and the experimental results are shown in Table 1.

[0027] Table 1 Performance test results of matte PE film for cotton wipes packaging

[0028] Note: Test method for heat sealing performance: Use HSG-C heat sealer to conduct heat sealing test on the sample, the sealing knife area is 15cm×1cm, the heat sealing temperature is 135℃, the heat sealing pressure is 0.2MPa, and the heat sealing time is 2.0s; By comprehensively analyzing the above experimental results, the following conclusions can be drawn: (1) The present invention utilizes solvent-free nano-SiO 2The fluid is used as a matting agent, and the matting PE film for cotton soft towel packaging prepared therefrom can significantly increase the haze and reduce the gloss, showing excellent matting performance, while also maintaining a high tear strength; (2) The solvent-free nano-SiO 2 The fluid can improve the longitudinal tensile strength of the matte PE film used for cotton wipe packaging, showing good mechanical properties; (3) The heat sealing strength of the matte PE film for cotton soft towel packaging prepared by the present invention meets the technical requirements of JB / T 9086-2007 "Plastic Bag Hot Press Sealing Machine" regarding sealing strength ≥ 15N (material thickness R, 0.08mm≤R<0.18mm).

Claims

1. A process for preparing a matte PE film for packaging cotton towels, characterized in that: The following steps are involved: Step 1: Using dibutyl phosphite, 2-(oxazolidin-3-yl)ethanol and di(hydrogenated tallow)phthalic acid amide as raw materials, a tetra-long-chain alkylated dibutyl phosphate monomer is synthesized, and the monomer is modified on the surface of SiO2 by a covalent grafting method to obtain a solvent-free nano-SiO2 fluid with a core-shell structure; Step 2: Filling the solvent-free nano-SiO2 fluid into the polyethylene and polypropylene mixed resin matrix, mixing to form a homogeneous system, and preparing the matte masterbatch; wherein the content of the solvent-free nano-SiO2 fluid in the matte masterbatch is 5-20wt%; Step three: using matte masterbatch as the outer layer raw material, high-density polyethylene resin as the middle layer raw material, and metallocene polyethylene resin as the inner layer raw material, a three-layer co-extrusion blow molding film-forming process is adopted to prepare a matte PE film for cotton soft towel packaging.

2. The process for preparing a matte PE film for packaging cotton towels according to claim 1, characterized in that: The chemical structural formula of the tetra-long-chain alkylated dibutyl phosphate monomer is: 。 3. The process for preparing a matte PE film for packaging cotton towels according to claim 2, characterized in that: The preparation method of the tetra-long-chain alkylated dibutyl phosphate monomer is as follows: The PH bond of dibutyl phosphite undergoes an epoxy ring-opening reaction with 2-(oxazolidin-3-yl)ethanol to generate dibutyl dihydroxyphosphate monomer; The tetra-long-chain alkylated dibutyl phosphate monomer is prepared by esterification reaction between the hydroxyl functional group of dihydroxy dibutyl phosphate monomer and the carboxyl functional group of di(hydrogenated tallow) phthalic acid amide.

4. The process for preparing a matte PE film for packaging cotton towels according to claim 1, characterized in that: The preparation method of the solvent-free nano-SiO2 fluid is as follows: under acidic conditions, the phosphorus hydroxyl functional groups obtained by the hydrolysis reaction of tetra-long-chain alkylated dibutyl phosphate monomers undergo a dehydration condensation reaction with the hydroxyl functional groups on the surface of hydroxylated SiO2, and the tetra-long-chain alkylated dibutyl phosphate monomers are modified on the SiO2 surface to prepare the solvent-free nano-SiO2 fluid.

5. The process for preparing a matte PE film for packaging cotton towels according to claim 4, characterized in that: The mass ratio of tetra-long-chain alkylated dibutyl phosphate monomer to hydroxylated SiO2 in the solvent-free nano-SiO2 fluid is 1:(3-10).

6. The process for preparing a matte PE film for packaging cotton towels according to claim 1, characterized in that: The formula of the matte masterbatch is: 70-90wt% low-density polyethylene resin, 5-15wt% polypropylene resin and 5-20wt% solvent-free nano-SiO2 fluid.

7. The process for preparing a matte PE film for packaging cotton towels according to claim 1, characterized in that: The product structure of the matt PE film for cotton soft towel packaging is: The first layer: a matte layer prepared with matte masterbatch as raw material, the amount of this layer is 30-45 parts by weight; The second layer: a support layer made of high-density polyethylene resin, the amount of which is 30-45 parts by weight; The third layer: a heat-sealing layer made of metallocene polyethylene resin, the amount of which is 10-40 parts by weight.

8. The process for preparing a matte PE film for packaging cotton towels according to claim 7, characterized in that: The preparation method of the matt PE film for cotton soft towel packaging is as follows: ingredients are prepared according to the raw material formula of the matt PE film for cotton soft towel packaging, and the raw materials of each layer are respectively put into the hoppers of three screw extruders of a three-layer co-extrusion film blow molding unit, and after stirring and mixing, the molten resin is converged at the head of the machine through a diverter, and is extruded and blow-molded through a die head, and the blowing ratio is controlled at 2.5-3.0, and the film is cooled and rolled to prepare the matt PE film for cotton soft towel packaging.

9. The process for preparing a matte PE film for packaging cotton towels according to claim 8, characterized in that: The process parameters of the screw extruder corresponding to the matt layer are set as follows: the temperatures of zones 1-3 are 140-155° C., 160-180° C., and 185-195° C., respectively; the flow channel temperature is 180-190° C.; and the rotation speed is 50-70 r / min.

10. A matte PE film for cotton soft towel packaging prepared by the process according to any one of claims 1 to 9, characterized in that: The matt PE film for packaging cotton wipes has a thickness of 50-150 μm.

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