BOPP (Biaxially-oriented Polypropylene) high-haze extinction type heat-sealing film and preparation method thereof

Abstract

The invention provides a BOPP high-haze extinction type heat sealing film and a preparation method thereof.The heat sealing film comprises an extinction bottom layer film, a base film and an extinction surface layer film, the base film is located between the extinction bottom layer film and the extinction surface layer film, and the extinction surface layer film is located above the extinction bottom layer film; the matting surface layer film comprises the following raw materials in parts by weight: 80-100 parts of polypropylene, 3-20 parts of a reinforcing agent and 0.1-5 parts of a matting agent. According to the BOPP high-haze matt type heat sealing film, the matt bottom layer film and the matt surface layer film are arranged on the upper surface and the lower surface of the base film, so that the haze and the matt performance of the heat sealing film are remarkably improved; moreover, a reinforcing agent and a matting agent are added into the matting bottom layer film and the matting surface layer film, the mechanical property and matting property of the film layer are improved, a binding agent is added into the base film, the binding force of the base film, the matting bottom layer film and the matting surface layer film is improved, and the mechanical property of the heat sealing film is integrally improved.

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering, and particularly relates to a BOPP high haze extinction heat-sealing film and a preparation method thereof. Background Art

[0002] Biaxially oriented polypropylene film is abbreviated as BOPP film. The heat-sealing film is one of the BOPP films and is mainly used for printing, compounding and bag making or wrapping.

[0003] In recent years, more and more products require a matte effect, making the products have a comfortable touch and delicate appearance, and the colors can be vividly reproduced during printing. However, at present, there are relatively large technical bottlenecks for BOPP heat-sealing films with certain mechanical properties and high haze. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and provides a BOPP high haze extinction heat-sealing film and a preparation method thereof.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: The present invention provides a BOPP high haze extinction heat-sealing film. The heat-sealing film includes an extinction bottom film, a base film and an extinction surface film. The base film is located between the extinction bottom film and the extinction surface film, and the extinction surface film is located above the extinction bottom film. The extinction surface film comprises the following raw materials in parts by weight: 80-100 parts of polypropylene, 3-20 parts of a reinforcing agent, and 0.1-5 parts of an extinction agent.

[0006] Further, the preparation method of the reinforcing agent comprises the following steps: Step 1: Add diethanolamine and methyl acrylate into a solvent, mix evenly, then carry out oil bath heating, stir magnetically under a nitrogen atmosphere, and carry out rotary evaporation after the reaction is completed to obtain a branched intermediate; Step 2: Mix nano-SiO₂ and the branched intermediate, add a first catalyst thereto under a nitrogen atmosphere, carry out oil bath heating, and obtain a hyperbranched intermediate after the reaction is completed. Add α-caprolactone and a second catalyst to the hyperbranched intermediate, and carry out a reaction under heating conditions. After the reaction is completed, centrifuge, wash and dry the product to obtain the reinforcing agent.

[0007] Further, the molar ratio of diethanolamine to methyl acrylate in Step 1 is 1:1-2; the solvent in Step 1 is methanol; the temperature of the oil bath heating step in Step 1 is 35-55 °C; the reaction time in Step 1 is 1-10 hours.

[0008] Further, the mass ratio of nano-SiO₂ in step 2 to diethanolamine in step 1 is 1-20:100; the first catalyst in step 2 is p-toluenesulfonic acid; the second catalyst in step 2 is stannous octoate; the temperature of the oil bath heating in step 2 is 100-150 °C; the temperature of the heating step in step 2 is 140-180 °C.

[0009] The enhancer graft-modifies nano-SiO₂ through branched polyester, improving the dispersibility of nano-SiO₂ in the matrix. Moreover, a long-chain alkyl structure is grafted on its side chains, significantly enhancing the mechanical properties and interfacial bonding force of the film in the polypropylene system; within the system, the long-chain alkyl structures of the enhancer and the matting agent jointly improve the binding performance with polypropylene.

[0010] Further, the preparation method of the matting agent includes the following steps: Mix talcum powder and an aqueous solution of sodium stearate, stir under heating conditions, then centrifuge, wash and dry the precipitate, then add an aqueous solution of calcium chloride, stir at room temperature, then centrifuge, wash and dry the precipitate, then mix with a solution of stearyl alcohol, stir at room temperature, then centrifuge, wash and dry the precipitate to obtain the matting agent.

[0011] The matting agent first adsorbs sodium stearate on the surface of talcum powder through intermolecular forces, then adds an aqueous solution of calcium chloride, and calcium ions combine with the stearate ions on the surface of talcum powder to form calcium stearate, thus forming talcum powder coated with calcium stearate. Finally, a solution of stearyl alcohol is added, and stearyl alcohol combines with sodium stearate between the talcum powder layers through intermolecular forces. Calcium stearate and talcum powder can play a synergistic matting role, and both the sodium stearate between the layers and stearyl alcohol contain long-chain alkyl groups, which can improve the water resistance of the film.

[0012] Further, the solid-liquid ratio of the talcum powder, the aqueous solution of sodium stearate, the aqueous solution of calcium chloride, and the solution of stearyl alcohol is 100 g:1000-1500 mL:1000-1500 mL:1000-1500 mL; the mass concentration of the aqueous solution of sodium stearate is 0.1-0.5%; the mass concentration of the aqueous solution of calcium chloride is 1-5%; the mass concentration of the solution of stearyl alcohol is 1-5%; the temperature of the heating step is 50-100 °C.

[0013] Further, the matting bottom layer film comprises the following raw materials in parts by weight: 80-100 parts of polypropylene, 1-10 parts of enhancer, and 0.1-5 parts of matting agent; the enhancer of the matting bottom layer film is the same as that of the matting surface layer film; the matting agent of the matting bottom layer film is the same as that of the matting surface layer film.

[0014] Furthermore, the base film comprises raw materials in the following parts by weight: 90 - 100 parts of polypropylene and 1 - 10 parts of binder.

[0015] Furthermore, the binder comprises chlorinated polypropylene, hydrogenated bisphenol A epoxy resin and γ - aminopropylmethyldiethoxysilane in a mass ratio of 10:1 - 8:1 - 5. The amino - containing siloxane reacts with the epoxy resin to form an epoxy glue prepolymer containing siloxane functional groups. There is no reaction between the siloxane in the epoxy prepolymer and chlorinated polypropylene. The epoxy glue and chlorinated polypropylene resin form an interpenetrating network structure, which improves the mechanical properties of the base film containing the binder and also improves the bonding strength between the base film and the matte bottom film and the matte top film.

[0016] The present invention also provides a preparation method of a BOPP high - haze matte heat - sealable film, comprising the following steps: First, 80 - 100 parts of polypropylene, 3 - 20 parts of reinforcing agent and 0.1 - 5 parts of matting agent are blended to obtain a matte top - layer material; then, 80 - 100 parts of polypropylene, 1 - 10 parts of reinforcing agent and 0.1 - 5 parts of matting agent are blended to obtain a matte bottom - layer material; then, 90 - 100 parts of polypropylene and 1 - 10 parts of binder are blended to obtain a base - layer material; finally, the base - layer material is fed into a main extruder for melting, the matte top - layer material and the matte bottom - layer material are separately fed into two auxiliary extruders for melting, and are extruded through a three - layer die head, and after cooling, biaxial stretching and shaping, the BOPP high - haze matte heat - sealable film is obtained.

[0017] Compared with the prior art, the present invention has the following advantages: The BOPP high - haze matte heat - sealable film of the present invention significantly improves the haze and matte performance of the heat - sealable film by setting a matte bottom film and a matte top film on the upper and lower surfaces of the base film; moreover, by adding a reinforcing agent and a matting agent to the matte bottom film and the matte top film, the mechanical properties and matte performance of the film layer are improved. By adding a binder to the base film, the bonding strength between the base film and the matte bottom film and the matte top film is improved, and overall, the mechanical properties of the heat - sealable film are improved. Specific Embodiments

[0018] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0019] The specific preparation methods of the reinforcing agents used in the embodiments and comparative examples of the present invention are as follows: (1)Mix 1 mol of diethanolamine, 100 mL of methanol and 1 mol of methyl acrylate, and under the condition of a 40 °C oil bath and in a nitrogen atmosphere, stir the reaction magnetically for 3 h. After the reaction is completed, remove the remaining methyl acrylate and methanol by rotary evaporation to obtain a light yellow transparent branched intermediate; (2)Mix nano-SiO₂ and the branched intermediate with a mass ratio of 1:10. Under the condition of a nitrogen atmosphere, use p-toluenesulfonic acid as a catalyst and heat under the condition of a 120 °C oil bath, stir the reaction for 10 h. Add ε-caprolactone and stannous octoate as a catalyst, and react at 150 °C for 35 h. After the reaction is completed, centrifuge, wash, and dry to obtain the enhancer.

[0020] The specific preparation methods of the matting agents used in the examples and comparative examples of the present invention are as follows: Mix 10 g of talcum powder with 100 mL of an aqueous sodium stearate solution (mass concentration 0.5%), stir at 80 °C for 2 h, take the precipitate after centrifugation, wash and dry it, and then mix it with 100 mL of an aqueous calcium chloride solution (mass concentration 5%), stir at room temperature for 2 h, then centrifuge, take the precipitate, wash and dry it, and then mix it with 100 mL of an anhydrous ethanol solution of stearyl alcohol (mass concentration 5%), stir at room temperature for 2 h, then centrifuge, take the precipitate, wash and dry it to obtain the matting agent.

[0021] The binder used in the examples and comparative examples of the present invention includes chlorinated polypropylene, hydrogenated bisphenol A epoxy resin and γ-aminopropylmethyldiethoxysilane with a mass ratio of 10:6:2.

[0022] The present invention will be described in detail below with reference to the examples.

[0023] Example 1 A preparation method of a BOPP high haze matting heat-sealing film includes the following steps: (1)Blend 90 parts of polypropylene, 15 parts of the enhancer and 0.5 part of the matting agent to obtain a matting surface layer material; (2)Blend 90 parts of polypropylene, 5 parts of the enhancer and 0.2 part of the matting agent to obtain a matting bottom layer material; (3)Blend 90 parts of polypropylene and 2 parts of the binder to obtain a base layer material; (4)Feed the base layer material into a main extruder for melting, feed the matting surface layer material and the matting bottom layer material into two auxiliary extruders for melting respectively, extrude through a three-layer structure die head, and after cooling, biaxial stretching and shaping, obtain the BOPP high haze matting heat-sealing film.

[0024] Example 2 A preparation method of a BOPP high haze extinction heat-sealing film, comprising the following steps: (1) Blending 90 parts of polypropylene, 15 parts of reinforcing agent and 2 parts of matting agent to obtain a matting surface layer material; (2) Blending 90 parts of polypropylene, 5 parts of reinforcing agent and 2 parts of matting agent to obtain a matting bottom layer material; (3) Blending 90 parts of polypropylene and 2 parts of binder to obtain a base layer material; (4) Feeding the base layer material into a main extruder for melting, separately feeding the matting surface layer material and the matting bottom layer material into two auxiliary extruders for melting, extruding through a three-layer structure die head, and performing cooling, biaxial stretching and shaping to obtain the BOPP high haze extinction heat-sealing film.

[0025] Example 3 A preparation method of a BOPP high haze extinction heat-sealing film, comprising the following steps: (1) Blending 90 parts of polypropylene, 5 parts of reinforcing agent and 0.5 part of matting agent to obtain a matting surface layer material; (2) Blending 90 parts of polypropylene, 1 part of reinforcing agent and 0.2 part of matting agent to obtain a matting bottom layer material; (3) Blending 90 parts of polypropylene and 2 parts of binder to obtain a base layer material; (4) Feeding the base layer material into a main extruder for melting, separately feeding the matting surface layer material and the matting bottom layer material into two auxiliary extruders for melting, extruding through a three-layer structure die head, and performing cooling, biaxial stretching and shaping to obtain the BOPP high haze extinction heat-sealing film.

[0026] Comparative Example 1 A preparation method of a BOPP high haze extinction heat-sealing film, comprising the following steps: (1) Blending 90 parts of polypropylene and 0.5 part of matting agent to obtain a matting surface layer material; (2) Blending 90 parts of polypropylene and 0.2 part of matting agent to obtain a matting bottom layer material; (3) Blending 90 parts of polypropylene and 2 parts of binder to obtain a base layer material; (4) Feeding the base layer material into a main extruder for melting, separately feeding the matting surface layer material and the matting bottom layer material into two auxiliary extruders for melting, extruding through a three-layer structure die head, and performing cooling, biaxial stretching and shaping to obtain the BOPP high haze extinction heat-sealing film.

[0027] Comparative Example 2 A preparation method of a BOPP high haze extinction heat-sealing film, comprising the following steps: (1)Mix 90 parts of polypropylene, 15 parts of nano-SiO2 and 0.5 part of matting agent to obtain the matting surface layer material; (2)Mix 90 parts of polypropylene, 5 parts of nano-SiO2 and 0.2 part of matting agent to obtain the matting bottom layer material; (3)Mix 90 parts of polypropylene and 2 parts of binder to obtain the base layer material; (4)Feed the base layer material into the main extruder for melting, melt the matting surface layer material and the matting bottom layer material separately in two auxiliary extruders, extrude through a three-layer die head, and after cooling, biaxial stretching and shaping, obtain the BOPP high haze matting heat-sealing film.

[0028] Comparative Example 3 A method for preparing a BOPP high haze matting heat-sealing film, comprising the following steps: (1)Mix 90 parts of polypropylene and 15 parts of reinforcing agent to obtain the matting surface layer material; (2)Mix 90 parts of polypropylene and 5 parts of reinforcing agent to obtain the matting bottom layer material; (3)Mix 90 parts of polypropylene and 2 parts of binder to obtain the base layer material; (4)Feed the base layer material into the main extruder for melting, melt the matting surface layer material and the matting bottom layer material separately in two auxiliary extruders, extrude through a three-layer die head, and after cooling, biaxial stretching and shaping, obtain the BOPP high haze matting heat-sealing film.

[0029] Comparative Example 4 A method for preparing a BOPP high haze matting heat-sealing film, comprising the following steps: (1)Mix 90 parts of polypropylene, 15 parts of reinforcing agent and 0.5 part of talcum powder to obtain the matting surface layer material; (2)Mix 90 parts of polypropylene, 5 parts of reinforcing agent and 0.2 part of talcum powder to obtain the matting bottom layer material; (3)Mix 90 parts of polypropylene and 2 parts of binder to obtain the base layer material; (4)Feed the base layer material into the main extruder for melting, melt the matting surface layer material and the matting bottom layer material separately in two auxiliary extruders, extrude through a three-layer die head, and after cooling, biaxial stretching and shaping, obtain the BOPP high haze matting heat-sealing film.

[0030] Comparative Example 5 A method for preparing a BOPP high haze matting heat-sealing film, comprising the following steps: (1)Mix 90 parts of polypropylene, 15 parts of reinforcing agent and 0.5 part of matting agent to obtain the matting surface layer material; (2) Mix 90 parts of polypropylene, 5 parts of reinforcing agent and 0.2 parts of matting agent to obtain a matting bottom layer material; (3) Mix 90 parts of polypropylene to obtain a base layer material; (4) Feed the said base layer material into a main extruder for melting, and separately feed the said matting surface layer material and matting bottom layer material into two auxiliary extruders for melting. Extrude through a three-layer structure die head, and after cooling, biaxial stretching and shaping, obtain the said BOPP high haze matting heat-sealing film.

[0031] Compare the haze (GB / T 2410-2008), glossiness (GB / T 8807-1988) and elongation at break (GB / T 12026-2000) of the BOPP heat-sealing films obtained in Examples 1-3 with those of the BOPP heat-sealing films obtained in Comparative Examples 1-5. The results are shown in Table 1.

[0032] Table 1 Performance test results

[0033] As can be seen from Table 1, the haze, glossiness and elongation at break of the heat-sealing films obtained in Examples 1-3 are significantly improved compared with those in Comparative Examples 1-5; the combination of the reinforcing agent and the matting agent improves the strength and haze of both the matting surface layer film and the matting bottom layer film, and the use of the binder improves the strength of the base film, thereby improving the overall elongation at break of the heat-sealing film.

[0034] In Comparative Example 1, no reinforcing agent was used, and its elongation at break decreased significantly, and the haze also decreased slightly. In Comparative Example 2, the reinforcing agent was replaced with conventional nano-SiO2, and the haze of the heat-sealing film did not increase significantly; in Comparative Example 3, no matting agent was used, and compared with Examples 1-3, the haze decreased significantly, but the elongation at break improved; in Comparative Example 4, the matting agent was changed to talc powder, and the haze of the heat-sealing film improved, but there was still a gap compared with Examples 1-3; in Comparative Example 5, no binder was added to the base film, which had a great impact on the overall elongation at break of the heat-sealing film.

[0035] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A BOPP high haze matte heat-sealing film, characterized in that: The heat-sealing film described above comprises a matte bottom film, a base film, and a matte top film. The base film is located between the matte bottom film and the matte top film, and the matte top film is located above the matte bottom film. The matte top film comprises the following raw materials in parts by weight: 80-100 parts of polypropylene, 3-20 parts of a reinforcing agent, and 0.1-5 parts of a matting agent.

2. The BOPP high haze matte heat-sealing film according to claim 1, characterized in that: The preparation method of the reinforcing agent described above comprises the following steps: Step 1: Add diethanolamine and methyl acrylate into a solvent, mix evenly, then carry out oil bath heating, stir magnetically under a nitrogen atmosphere, and carry out rotary evaporation after the reaction is completed to obtain a branched intermediate. Step 2: Mix nano-SiO₂ and the branched intermediate, add a first catalyst thereto under a nitrogen atmosphere, carry out oil bath heating, and obtain a hyperbranched intermediate after the reaction is completed. Add ε-caprolactone and a second catalyst to the hyperbranched intermediate, and carry out a reaction under heating conditions. After the reaction is completed, centrifuge, wash, and dry the product to obtain the reinforcing agent.

3. The BOPP high haze matting heat-sealing film according to claim 2, characterized in that: In Step 1, the molar ratio of diethanolamine to methyl acrylate is 1:1-2; the solvent in Step 1 is methanol; the temperature of the oil bath heating step in Step 1 is 35-55 °C; the reaction time in Step 1 is 1-10 hours.

4. The BOPP high haze matting heat-sealing film according to claim 2, wherein: In Step 2, the mass ratio of nano-SiO₂ to diethanolamine in Step 1 is 1-20:100; the first catalyst in Step 2 is p-toluenesulfonic acid; the second catalyst in Step 2 is stannous octoate; the temperature of the oil bath heating in Step 2 is 100-150 °C; the temperature of the heating step in Step 2 is 140-180 °C.

5. The BOPP high haze matting heat-sealing film according to claim 1, characterized in that: The preparation method of the matting agent described above comprises the following steps: Mix talcum powder and an aqueous sodium stearate solution, stir under heating conditions, then centrifuge, wash and dry the precipitate, then add an aqueous calcium chloride solution thereto, stir at room temperature, then centrifuge, wash and dry the precipitate, then mix with a stearyl alcohol solution, stir at room temperature, then centrifuge, wash and dry the precipitate to obtain the matting agent.

6. The BOPP high haze matting heat-sealing film according to claim 5, characterized in that: The solid-liquid ratio of the talcum powder, the aqueous sodium stearate solution, the aqueous calcium chloride solution, and the stearyl alcohol solution is 100 g:1000-1500 mL:1000-1500 mL:1000-1500 mL; the mass concentration of the aqueous sodium stearate solution is 0.1-0.5%; the mass concentration of the aqueous calcium chloride solution is 1-5%; the mass concentration of the stearyl alcohol solution is 1-5%; the temperature of the heating step is 50-100 °C.

7. The BOPP high haze extinction heat-sealing film according to claim 1, characterized in that: The matte bottom film comprises the following raw materials in parts by weight: 80-100 parts of polypropylene, 1-10 parts of a reinforcing agent, and 0.1-5 parts of a matting agent; the reinforcing agent of the matte bottom film is the same as that of the matte top film; the matting agent of the matte bottom film is the same as that of the matte top film.

8. The BOPP high haze matte heat-sealing film according to claim 1, characterized in that: The base film comprises the following raw materials in parts by weight: 90-100 parts of polypropylene, and 1-10 parts of a binder.

9. The BOPP high haze matting heat-sealing film according to claim 8, characterized in that: The binder described above comprises chlorinated polypropylene, hydrogenated bisphenol A epoxy resin and γ-aminopropylmethyldiethoxysilane with a mass ratio of 10:1 - 8:1 - 5.

10. The preparation method of the BOPP high haze matting heat-sealing film according to any one of claims 1-9, characterized in that: It includes the following steps: First, 80 - 100 parts of polypropylene, 3 - 20 parts of reinforcing agent and 0.1 - 5 parts of matting agent are blended to obtain a matting surface layer material; then, 80 - 100 parts of polypropylene, 1 - 10 parts of reinforcing agent and 0.1 - 5 parts of matting agent are blended to obtain a matting bottom layer material; then, 90 - 100 parts of polypropylene and 1 - 10 parts of binder are blended to obtain a base layer material; finally, the base layer material is fed into a main extruder for melting, the matting surface layer material and the matting bottom layer material are separately fed into two auxiliary extruders for melting, and are extruded through a three-layer structure die head, and after cooling, biaxial stretching and shaping, the BOPP high haze matting heat-sealing film is obtained.

Images