Preparation process of a matte PE film for cotton soft towel packaging

Abstract

The present invention relates to the technical field of matte films, and discloses a preparation process of a matte PE film for cotton soft towel packaging, including: using dibutyl phosphite, 2-(oxazolidin-3-yl)ethanol, and di(hydrogenated tallow-based) phthalic acid amide as raw materials to synthesize a tetra-long-chain alkylated dibutyl phosphate monomer, modifying it on the surface of SiO2 by covalent grafting method to obtain a solvent-free nano-SiO2 fluid with a core-shell structure; filling the solvent-free nano-SiO2 fluid into a mixed resin matrix of polyethylene and polypropylene, mixing to form a homogeneous system, and preparing a matte masterbatch; using the matte masterbatch as the outer layer raw material, high-density polyethylene resin as the intermediate layer raw material, and metallocene polyethylene resin as the inner layer raw material, and adopting a three-layer co-extrusion blow molding process to prepare a matte PE film for cotton soft towel packaging. The matte PE film developed by the present invention exhibits very excellent matte performance while only slightly decreasing in tear resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of matte films, and specifically to a preparation process of a matte PE film for cotton soft towel packaging. Background Art

[0002] A matte film is a packaging film with a surface similar to paper, having very low gloss, high haze, and a diffuse reflection matte effect. The reflected light on its surface is weak and soft, the surface glossiness is less than 15%, and the haze is generally above 70%. It has many advantages such as a comfortable hand feel, a soft and delicate matte appearance, and the ability to vividly reproduce colors during printing. Currently, it has become an important functional material for enhancing the texture of cotton soft towel packaging.

[0003] Almost most plastic varieties (such as PA, PET, PC, PE, and PP) can be used to produce matte films, but the technical means for realizing the matte effect are different. Currently, the main ways to achieve the matte effect are as follows: adding light-absorbing substances such as graphite; adding matting agents such as SiO2; using secondary processing such as roll embossing, solvent, and chemical etching; and polymer itself property matte, such as polyvinyl chloride PVC and polylactic acid PLA. Among them, adding SiO2 matting agent to PE blown film to prepare matte PE film is a technically feasible solution that conforms to 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 situation of the development of existing technologies, the present invention develops a PE film with more excellent performance, more appropriate cost, and having a matte function for use in the packaging of cotton soft towels.

[0005] A preparation process of a matte PE film for cotton soft towel packaging includes the following steps:

[0006] Step 1: Using dibutyl phosphite, 2-(oxazolidin-3-yl)ethanol, and di(hydrogenated tallow) phthalic acid amide as raw materials, synthesize tetra-long-chain alkylated dibutyl phosphate monomer, and modify it on the surface of SiO2 by covalent grafting method to obtain a solvent-free nano-SiO2 fluid with a core-shell structure;

[0007] Step 2: Fill the solvent-free nano-SiO2 fluid into a mixed resin matrix of polyethylene and polypropylene, and mix to form a homogeneous system to prepare a matte masterbatch; wherein, the content of the solvent-free nano-SiO2 fluid in the matte masterbatch is 5-20 wt%;

[0008] Step 3: Using the 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, adopt a three-layer co-extrusion blow molding process to prepare a matte PE film for cotton soft towel packaging.

[0009] Preferably, the preparation method of the tetra-long-chain alkylated dibutyl phosphate monomer is as follows:

[0010] Through the epoxy ring-opening reaction of the P-H bond of dibutyl phosphite with 2-(oxazolidin-3-yl)ethanol, the dibutyl phosphate monomer with dihydroxy groups is generated;

[0011] Using the hydroxyl functional group of the dibutyl phosphate monomer with dihydroxy groups and the carboxyl functional group of bis(hydrogenated tallow) phthalic acid amide to carry out an esterification reaction, the tetra-long-chain alkylated dibutyl phosphate monomer is prepared.

[0012] Preferably, the preparation method of the solvent-free nano-SiO2 fluid is as follows: Under acidic conditions, through the dehydration condensation reaction of the phospho-hydroxy functional group obtained by the hydrolysis reaction of the tetra-long-chain alkylated dibutyl phosphate monomer with the hydroxyl functional group on the surface of hydroxylated SiO2, the tetra-long-chain alkylated dibutyl phosphate monomer is modified on the surface of SiO2 to prepare the solvent-free nano-SiO2 fluid.

[0013] Preferably, the mass ratio of the tetra-long-chain alkylated dibutyl phosphate monomer to hydroxylated SiO2 in the solvent-free nano-SiO2 fluid is 1:(3 - 10).

[0014] Preferably, the formula of the matting masterbatch is: 70 - 90 wt% low-density polyethylene resin, 5 - 15 wt% polypropylene resin, and 5 - 20 wt% solvent-free nano-SiO2 fluid.

[0015] Preferably, the product structure of the matting PE film for cotton soft towel packaging is as follows:

[0016] The first layer: a matting layer prepared from the matting masterbatch, and the dosage of this layer is 30 - 45 parts by weight;

[0017] The second layer: a support layer prepared from high-density polyethylene resin, and the dosage of this layer is 30 - 45 parts by weight;

[0018] The third layer: a heat-sealing layer prepared from metallocene polyethylene resin, and the dosage of this layer is 10 - 40 parts by weight.

[0019] Preferably, the preparation method of the matting PE film for cotton soft towel packaging is as follows: According to the raw material formula of the matting PE film for cotton soft towel packaging for batching, each layer of raw materials is respectively put into the hoppers of three screw extruders of a three-layer coextrusion film blowing machine. After stirring and mixing, the molten resin converges at the head through a diverter, is extruded and blown through a die head, the blow-up ratio is controlled at 2.5 - 3.0, cooled and wound up to prepare the matting PE film for cotton soft towel packaging.

[0020] Preferably, the process parameters of the screw extruder corresponding to the matting layer are set as follows: the temperatures of zones 1-3 are 140-155°C, 160-180°C, and 185-195°C respectively, the runner temperature is 180-190°C, and the rotation speed is 50-70 r / min.

[0021] The thickness of a matting PE film for cotton soft towel packaging prepared according to the above process is 50-150 μm.

[0022] Beneficial effects:

[0023] The present invention has developed a tetra-long-chain alkylated dibutyl phosphate monomer, and through a covalent grafting method, the alkyl long chain is grafted onto the surface of nano-SiO2 to prepare a new solvent-free nano-SiO2 fluid. The solvent-free nano-SiO2 fluid is filled into a mixed resin matrix composed of polyethylene and polypropylene to form a homogeneous system, and a matting masterbatch is prepared.

[0024] Experimental results show that the development of the solvent-free nano-SiO2 fluid as a technical means eliminates the adverse effects of the nano-SiO2 matting agent on the tear strength of the PE film.

[0025] Using the matting masterbatch as the raw material for the outer matting layer, high-density polyethylene resin as the raw material for the middle layer support layer, and metallocene polyethylene resin as the raw material for the inner layer heat-sealing layer, a matting PE film is prepared by a three-layer co-extrusion blow molding process.

[0026] Through experimental results, it is found that the matting PE film prepared by the present invention exhibits very excellent matting performance while only slightly decreasing in tear resistance, and it can be used as a matting material to improve the packaging texture of cotton soft towels. Specific embodiments

[0027] The main raw materials used in the present invention are as follows:

[0028] Low-density polyethylene resin (LDPE), grade LD 150DW, melt mass flow rate (MFR) of 0.3 g / 10 min (220°C, 2 kg);

[0029] Polypropylene resin (PP), grade R520Y, MFR of 1.8 g / 10 min (230°C, 2 kg);

[0030] Hydroxylated silica nanopowder, particle size of 10-20 nm;

[0031] High-density polyethylene resin (HDPE), grade FB5600;

[0032] Metallocene polyethylene resin (m-LLDPE), grade SP4020.

[0033] Experimental Example:

[0034] In view of the technical problem that adding SiO2 matting agent will cause a serious decrease in the tear strength of the film, the present invention has developed a solvent-free nano-SiO2 fluid. By mixing the solvent-free nano-SiO2 fluid with a polyolefin resin matrix, a matting masterbatch is formed. During this process, the solvent-free nano-SiO2 fluid migrates into the interior of the polyolefin resin matrix. While solving the problem of agglomeration of SiO2 nanoparticles, it can effectively improve the interfacial compatibility of the matting material, thereby overcoming the technical defect that the SiO2 matting agent causes a serious decrease in the tear strength of the PE film;

[0035] Using dibutyl phosphite, 2-(oxazolidin-3-yl)ethanol and di(hydrogenated tallow)phthalic acid amide as raw materials, tetra-long-chain alkylated dibutyl phosphate monomer is designed and synthesized, and it is modified on the surface of SiO2 to obtain a solvent-free nano-SiO2 fluid with a core-shell structure;

[0036] The preparation steps of the solvent-free nano-SiO2 fluid are as follows:

[0037] Step 1: Prepare tetra-long-chain alkylated dibutyl phosphate monomer, and its preparation method is:

[0038] First, the P-H bond of dibutyl phosphite undergoes a ring-opening reaction with 2-(oxazolidin-3-yl)ethanol to generate a dihydroxy dibutyl phosphate monomer, and its chemical structural formula is:

[0039] ;

[0040] Then, the esterification reaction occurs between the hydroxyl functional group of the dihydroxy dibutyl phosphate monomer and the carboxyl functional group of di(hydrogenated tallow)phthalic acid amide to prepare tetra-long-chain alkylated dibutyl phosphate monomer, and its chemical structural formula is:

[0041] ;

[0042] The specific experimental steps for preparing tetra-long-chain alkylated dibutyl phosphate monomer are:

[0043] First, add 1.9 g of dibutyl phosphite, 1.2 g of 2-(oxazolidin-3-yl)ethanol and 50 mL of methanol into a three-necked flask. Under mechanical stirring, heat up to 70 °C and reflux for 6 h. Rotate evaporate to remove the solvent and vacuum dry to obtain the dibutyl dihydroxyphosphate monomer. Then, add 1.5 g of the dibutyl dihydroxyphosphate monomer and 30 mL of N,N-dimethylformamide into the three-necked flask, stir at room temperature until completely dissolved, successively add 50 mL of N,N-dimethylformamide solution containing 6.7 g of bis(hydrogenated tallow) phthalic acid amide and 5 drops of concentrated sulfuric acid, rotate evaporate to remove the solvent, wash with ethanol and vacuum dry to obtain the tetra-long-chain alkylated dibutyl phosphate monomer;

[0044] The 1H NMR characterization results of the tetra-long-chain alkylated dibutyl phosphate monomer are as follows: 1 H NMR(CDCl3, 400 MHz) 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, 4H), 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);

[0045] Step 2: Prepare a solvent-free nano-SiO2 fluid. The preparation method is as follows: Under acidic conditions, the phospho-hydroxy functional groups obtained by the hydrolysis reaction of the tetra-long-chain alkylated dibutyl phosphate monomer undergo dehydration condensation reaction with the hydroxy functional groups on the surface of hydroxylated SiO2 to modify the tetra-long-chain alkylated dibutyl phosphate monomer on the surface of SiO2, and the alkyl long chains form a crown layer on the surface of SiO2 to prepare a solvent-free nano-SiO2 fluid with a core-shell structure;

[0046] Among them, the core layer is SiO2 nanoparticles surrounded by the tetra-long-chain alkylated dibutyl phosphate monomer, and the shell layer is composed of alkyl long chains. The shell layer composed of the alkyl long chains is equivalent to a "solvent" and provides fluidity for the SiO2 nanoparticles;

[0047] The specific experimental steps for preparing the solvent-free nano-SiO2 fluid are as follows: Add 1 g of tetra-long-chain alkylated dibutyl phosphate monomer, 15 mL of ethanol, and 5 mL of deionized water into a beaker. Adjust the pH of the solution to 4 with 0.1 mol / L hydrochloric acid, stir and disperse at room temperature for 30 min. Then add 100 mL of a mixed solution containing 8 g of hydroxylated silica nanopowder (the mixed solution is composed of 3 volume parts of ethanol and 1 volume part of deionized water), ultrasonically mix for 5 min, heat up to 60 °C and stir and react for 4 h. Centrifuge, and repeatedly wash with anhydrous ethanol and deionized water by centrifugation, and then dry in vacuum at 80 °C for 2 h to obtain the solvent-free nano-SiO2 fluid. Example 1:

[0048] Prepare the matting masterbatch I, whose formula is: 85 wt% low-density polyethylene resin, 10 wt% polypropylene resin, and 5 wt% solvent-free nano-SiO2 fluid. The preparation method is as follows: Weigh the raw materials according to the formula of the matting masterbatch I, add the formula raw materials into a high-speed mixer and mix evenly, then extrude and pelletize through a twin-screw extruder, and dry in vacuum at 80 °C for 6 h to obtain the matting masterbatch I;

[0049] 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 300 r / min. Example 2:

[0050] Prepare the matting masterbatch II, whose formula is: 80 wt% low-density polyethylene resin, 10 wt% polypropylene resin, and 10 wt% solvent-free nano-SiO2 fluid. The preparation method is the same as that of the matting masterbatch I. Example 3:

[0051] Prepare the matting masterbatch III, whose formula is: 70 wt% low-density polyethylene resin, 10 wt% polypropylene resin, and 20 wt% solvent-free nano-SiO2 fluid. The preparation method is the same as that of the matting masterbatch I. Example 4:

[0052] A matting PE film I for cotton soft towel packaging, whose product structure is:

[0053] The first layer: a matting layer prepared from the matting masterbatch I, and the dosage of this layer is 40 parts by weight;

[0054] The second layer: a support layer prepared from high-density polyethylene resin, and the dosage of this layer is 40 parts by weight;

[0055] The third layer: a heat-sealing layer prepared from metallocene polyethylene resin, and the dosage of this layer is 20 parts by weight. Example 5:

[0056] Preparation process of a matte PE film Ⅰ for cotton soft towel packaging, and the specific preparation steps are as follows:

[0057] According to the raw material formula of the matte PE film Ⅰ for cotton soft towel packaging, ingredients are prepared, and the raw materials of each layer are respectively put into the hoppers of three screw extruders of a three-layer coextrusion film blowing machine. After stirring and mixing, the molten resin converges at the head through a diverter, is extruded and blown through a die head, and the blow-up ratio is controlled at 2.9. After cooling and winding, a matte PE film Ⅰ for cotton soft towel packaging with a thickness of 100 μm is prepared;

[0058] Among them, 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 runner temperature is 185 °C, and the rotation speed is 60 r / min;

[0059] The process parameters of the screw extruder corresponding to the support layer are set as follows: the temperatures of zones 1 - 3 are 130 °C, 150 °C, and 175 °C respectively, the runner temperature is 170 °C, and the rotation speed is 30 r / min;

[0060] 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 runner temperature is 160 °C, and the rotation speed is 30 r / min. Example Six:

[0061] A matte PE film Ⅱ for cotton soft towel packaging, the difference in its product structure from the matte PE film Ⅰ for cotton soft towel packaging in Example Four is only that: the matte masterbatch Ⅱ is used to replace the matte masterbatch Ⅰ;

[0062] The preparation process of the matte PE film Ⅱ for cotton soft towel packaging is the same as that of the matte PE film Ⅰ for cotton soft towel packaging in Example Five. Example Seven:

[0063] A matte PE film Ⅲ for cotton soft towel packaging, the difference in its product structure from the matte PE film Ⅰ for cotton soft towel packaging in Example Four is only that: the matte masterbatch Ⅲ is used to replace the matte masterbatch Ⅰ;

[0064] The preparation process of the matte PE film Ⅲ for cotton soft towel packaging is the same as that of the matte PE film Ⅰ for cotton soft towel packaging in Example Five.

[0065] Comparative Example One:

[0066] Prepare PE film a: Compared with the matte PE film Ⅰ for cotton soft towel packaging, the difference is only that: the blend masterbatch is used to replace the matte masterbatch Ⅰ;

[0067] Among them, the formulation of the blend masterbatch is: 80 wt% low-density polyethylene resin, 10 wt% polypropylene resin, and 10 wt% hydroxylated silica nanopowder, and its preparation method is the same as that of the matting masterbatch I.

[0068] Comparative Example 2:

[0069] Prepare PE film b: Compared with the matting PE film I for cotton soft towel packaging, the only difference is that low-density polyethylene resin is used to replace the matting masterbatch I.

[0070] Performance test:

[0071] Perform performance tests on the matting PE film samples for cotton soft towel packaging, and the experimental results are shown in Table 1.

[0072] Table 1 Performance experimental results of the matting PE film for cotton soft towel packaging

[0073]

[0074] Note: Test method for heat-sealing performance: Use an HSG-C type heat-sealing instrument to conduct heat-sealing experiments on the samples. The sealing knife area is 15 cm × 1 cm, the heat-sealing temperature is 135 °C, the heat-sealing pressure is 0.2 MPa, and the heat-sealing time is 2.0 s;

[0075] Through comprehensive analysis of the above experimental results, the following conclusions can be drawn:

[0076] (1) In the present invention, the solvent-free nano-SiO2 fluid is used as a matting agent. The matting PE film for cotton soft towel packaging prepared thereby can, on the one hand, significantly improve the haze and reduce the gloss, showing excellent matting performance, and on the other hand, maintain a relatively high tear strength;

[0077] (2) The solvent-free nano-SiO2 fluid independently developed in the present invention can improve the longitudinal tensile strength of the matting PE film for cotton soft towel packaging, showing good mechanical properties;

[0078] (3) The heat-sealing strength of the matting PE film for cotton soft towel packaging prepared in the present invention meets the technical requirements of JB / T 9086-2007 "Plastic Bag Heat Press Sealing Machine" regarding the sealing strength ≥ 15 N (material thickness R, 0.08 mm ≤ R < 0.18 mm).

Claims

1. A preparation process of a matte PE film for cotton soft towel packaging, characterized in that, It includes the following steps: Step 1: Using dibutyl phosphite, 2-(oxazolidin-3-yl)ethanol, and bis(hydrogenated tallow) phthalic acid amide as raw materials, synthesize a tetra-long-chain alkylated dibutyl phosphate monomer, and modify it on the surface of SiO2 by covalent grafting method to obtain a solvent-free nano-SiO2 fluid with a core-shell structure; Step 2: Fill the solvent-free nano-SiO2 fluid into a mixed resin matrix of polyethylene and polypropylene, mix to form a homogeneous system, and prepare a matting masterbatch; wherein, the content of the solvent-free nano-SiO2 fluid in the matting masterbatch is 5-20 wt%; Step 3: Using the matting 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, adopt a three-layer co-extrusion blow molding process to prepare a matting PE film for cotton soft towel packaging.

2. The preparation process of a matte PE film for cotton soft towel packaging according to claim 1, characterized in that, The chemical structural formula of the tetra-long-chain alkylated dibutyl phosphate monomer is: 。 3. The preparation process of a matte PE film for cotton soft towel packaging according to claim 2, characterized in that, The preparation method of the tetra-long-chain alkylated dibutyl phosphate monomer is: Through the epoxy ring-opening reaction of the P-H bond of dibutyl phosphite with 2-(oxazolidin-3-yl)ethanol, generate a dihydroxy dibutyl phosphate monomer; Utilize the esterification reaction between the hydroxyl functional group of the dihydroxy dibutyl phosphate monomer and the carboxyl functional group of bis(hydrogenated tallow) phthalic acid amide to prepare the tetra-long-chain alkylated dibutyl phosphate monomer.

4. The preparation process of a matte PE film for cotton soft towel packaging according to claim 1, characterized in that, The preparation method of the solvent-free nano-SiO2 fluid is: Under acidic conditions, through the dehydration condensation reaction between the phospho-hydroxy functional group obtained by the hydrolysis reaction of the tetra-long-chain alkylated dibutyl phosphate monomer and the hydroxyl functional group on the hydroxylated SiO2 surface, modify the tetra-long-chain alkylated dibutyl phosphate monomer on the SiO2 surface to prepare a solvent-free nano-SiO2 fluid.

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

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

7. The preparation process of a matte PE film for cotton soft towel packaging according to claim 1, characterized in that, The product structure of the matting PE film for cotton soft towel packaging is: The first layer: A matting layer prepared from the matting masterbatch, and the dosage of this layer is 30-45 parts by weight; The second layer: A support layer prepared from high-density polyethylene resin, and the dosage of this layer is 30-45 parts by weight; The third layer: A heat-sealing layer prepared from metallocene polyethylene resin, and the dosage of this layer is 10-40 parts by weight.

8. The preparation process of a matte PE film for cotton soft towel packaging according to claim 7, characterized in that, The preparation method of the matting PE film for cotton soft towel packaging is: According to the raw material formula of the matting PE film for cotton soft towel packaging, proportion the ingredients, put the raw materials of each layer into the hoppers of three screw extruders of a three-layer co-extrusion film blowing unit respectively. After stirring and mixing, the molten resin converges at the head through a diverter, is extruded and blown through a die head, and the blow-up ratio is controlled at 2.5-3.0, then cooled and wound up to prepare the matting PE film for cotton soft towel packaging.

9. The preparation process of a matte PE film for cotton soft towel packaging according to claim 8, characterized in that, The process parameters of the screw extruder corresponding to the matting layer are set as follows: the temperatures of zones 1-3 are 140-155°C, 160-180°C, and 185-195°C respectively, the runner 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 1-9, characterized in that, The thickness of the matting PE film for cotton soft towel packaging is 50-150 μm.

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