阅读说明：本技术 一种高热封强度耐穿刺bopp薄膜及其制备方法 (High-heat-seal-strength puncture-resistant BOPP film and preparation method thereof ) 是由 彭超 于 2019-10-09 设计创作，主要内容包括：本发明公开了一种高热封强度耐穿刺BOPP薄膜,依次由电晕层、芯层、热封层构成；所述电晕层的原料按重量份由均聚聚丙烯95-98份和抗粘母料A2-5份组成；所述抗粘母料A的原料按重量份由无规则二氧化硅30-50份和均聚聚丙烯50-70份组成；所述芯层的原料按重量份由均聚聚丙烯80-85份、芥酸酰胺类爽滑剂1-5份和SBS苯乙烯类热塑性弹性体10-15份组成；所述热封层的原料按重量份由茂金属三元共聚聚丙烯70-80份、线性低密度聚乙烯20-25份和抗粘母料B 2-6份组成；所述抗粘母料B的原料按重量份由玻璃微珠40-60份和二元共聚聚丙烯40-60份组成。本发明还公开了上述BOPP薄膜的制备方法。(The invention discloses a high-heat-seal-strength puncture-resistant BOPP film which sequentially comprises a corona layer, a core layer and a heat seal layer; the raw materials of the corona layer consist of 95-98 parts of homopolymerized polypropylene and 2-5 parts of anti-sticking master batch by weight; the raw materials of the anti-sticking master batch A consist of 30-50 parts of random silicon dioxide and 50-70 parts of homopolymerized polypropylene according to parts by weight; the core layer is prepared from 80-85 parts by weight of homopolymerized polypropylene, 1-5 parts by weight of erucamide slipping agent and 10-15 parts by weight of SBS styrene thermoplastic elastomer; the raw materials of the heat sealing layer consist of 70-80 parts of metallocene ternary copolymer polypropylene, 20-25 parts of linear low-density polyethylene and 2-6 parts of anti-sticking master batch B in parts by weight; the raw materials of the anti-sticking master batch B comprise 40-60 parts of glass beads and 40-60 parts of binary copolymerized polypropylene in parts by weight. The invention also discloses a preparation method of the BOPP film.)

1. A high heat-seal strength puncture-resistant BOPP film is characterized by sequentially comprising a corona layer, a core layer and a heat-seal layer; the raw materials of the corona layer consist of 95-98 parts of homopolymerized polypropylene and 2-5 parts of anti-sticking master batch by weight; the raw materials of the anti-sticking master batch A consist of 30-50 parts of random silicon dioxide and 50-70 parts of homopolymerized polypropylene according to parts by weight;

the core layer is prepared from 80-85 parts by weight of homopolymerized polypropylene, 1-5 parts by weight of erucamide slipping agent and 10-15 parts by weight of SBS styrene thermoplastic elastomer;

the raw materials of the heat sealing layer consist of 70-80 parts of metallocene ternary copolymer polypropylene, 20-25 parts of linear low-density polyethylene and 2-6 parts of anti-sticking master batch B in parts by weight; the raw materials of the anti-sticking master batch B comprise 40-60 parts of glass beads and 40-60 parts of binary copolymerized polypropylene in parts by weight.

2. The high heat seal strength puncture resistant BOPP film according to claim 1, wherein the corona layer has a thickness of 4 to 8% of the thickness of the BOPP film, the core layer has a thickness of 75 to 80% of the thickness of the BOPP film, and the heat seal layer has a thickness of 15 to 20% of the thickness of the BOPP film.

3. The high heat seal strength puncture resistant BOPP film according to claim 1 or 2, wherein the melt index of the homo-polypropylene is 2.5 to 3.5g/10 min.

4. The high heat-seal strength puncture-resistant BOPP film according to any one of claims 1 to 3, wherein the random silica has two particle size ranges, the particle size ranges are 1 to 2 μm and 2 to 4 μm, and the weight ratio of the random silica having the particle size of 1 to 2 μm to the random silica having the particle size of 2 to 4 μm is 0.5 to 1.5: 3.5-4.5.

5. The high heat seal strength puncture resistant BOPP film according to any one of claims 1 to 4, wherein the glass beads have a particle size of 2 to 4 μm.

6. The high heat seal strength puncture resistant BOPP film according to any one of claims 1 to 5, wherein the high heat seal strength puncture resistant BOPP film has a thickness of 20 to 50 μm.

7. A method for preparing the high heat seal strength puncture-resistant BOPP film according to any one of claims 1 to 6, which comprises the following steps:

s1, extruding, plasticizing and melting the core layer raw materials to obtain a core layer melt; heating and melting a corona layer raw material to obtain a corona layer melt; heating and melting the heat seal layer raw material to obtain a heat seal layer melt;

s2, respectively filtering the corona layer melt, the core layer melt and the heat seal layer melt, converging and extruding the melts at a lip of a three-layer die head to form a membrane, attaching the membrane to a chill roll by a high-pressure air knife to be quenched to form a cast sheet, and cooling and shaping the cast sheet by circulating cooling water;

s3, longitudinally stretching the casting sheet to obtain a thick film, transversely stretching, heat setting, and naturally cooling to room temperature to obtain the puncture-resistant BOPP film with high heat-seal strength, wherein during longitudinal stretching, the preheating temperature of the corona layer is 150-.

8. The method for preparing a puncture-resistant BOPP film with high heat-seal strength as claimed in claim 7, wherein in S3, the preheating temperature for transverse stretching is 175-180 ℃, the transverse stretching temperature is 155-160 ℃, and the transverse stretching multiple is 8-10.

9. The method for preparing a high heat-seal strength puncture-resistant BOPP film as claimed in claim 7 or 8, wherein the heat-setting temperature is 165-170 ℃ in S3.

10. The method for preparing a high heat-seal strength puncture-resistant BOPP film according to any one of claims 7 to 9, wherein in S2, the filter screen is 400 mesh and the pressure of the high-pressure air knife is 260 bar.

Technical Field

The invention relates to the technical field of BOPP films, in particular to a high-heat-seal-strength puncture-resistant BOPP film and a preparation method thereof.

Background

In the field of packaging of foods and medicines, particularly heavy objects and hard objects, the traditional packaging film is difficult to meet the requirements of high-strength heat sealing and puncture resistance. At present, most of common packages in the market are: the packaging bag has the following structures of OPP/LLDPE, NY/LLDPE, PET/CPP, PET/VMPET/CPP, PET/NY/CPP and the like, and has the following problems: (1) the impact resistance of the packaging bag is poor, the packaging bag is easily damaged by external force in the processes of transportation, loading and unloading and shelf placement, the phenomena of bag breaking and bag opening are easily caused, the appearance of a packaged product is influenced, and the due effect of the packaging bag cannot be achieved; (2) the smoothness of the packaging bag is poor, the opening performance is poor in the production process, the production efficiency is low, the utilization rate of the packaging bag is reduced, and the cost is wasted; (3) the heat seal strength of a common packaging bag is less than 20N/15mm, when the heat seal temperature is too high, the damage of a heat seal layer is easily caused, the protection performance of the packaging bag is reduced, the quality guarantee period of contents is greatly shortened, and the contents cannot reach the corresponding quality guarantee period; (4) the interlaminar peeling strength of the packaging bag is less than 1.0N/15mm, so that the breaking force is insufficient, the mechanical property of the packaging bag is poor, the packaging bag is layered, the packaging bag cannot achieve the due bearing effect, and the effective protection effect on the contents cannot be achieved; (5) the puncture performance of the packaging bag is less than 1.0N/mu m, and for fish and meat products containing bones and hard objects, the packaging bag is easy to puncture by product extrusion in transportation and stacking, the sealing performance of the packaging bag is damaged, and thus the puncture performance requirement on the packaging bag is high; (6) the composite processing process of the packaging material involves solvent and glue, has certain pollution to the environment and does not accord with the policy of green packaging industry.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a high-heat-seal-strength puncture-resistant BOPP film and a preparation method thereof.

The invention provides a high-heat-seal-strength puncture-resistant BOPP film which is sequentially composed of a corona layer, a core layer and a heat seal layer; the raw materials of the corona layer consist of 95-98 parts of homopolymerized polypropylene and 2-5 parts of anti-sticking master batch A in parts by weight; the raw materials of the anti-sticking master batch A consist of 30-50 parts of random silicon dioxide and 50-70 parts of homopolymerized polypropylene according to parts by weight;

the core layer is prepared from 80-85 parts by weight of homopolymerized polypropylene, 1-5 parts by weight of erucamide slipping agent and 10-15 parts by weight of SBS styrene thermoplastic elastomer;

the raw materials of the heat sealing layer consist of 70-80 parts of metallocene ternary copolymer polypropylene, 20-25 parts of linear low-density polyethylene and 2-6 parts of anti-sticking master batch B in parts by weight; the raw materials of the anti-sticking master batch B comprise 40-60 parts of glass beads and 40-60 parts of binary copolymerized polypropylene in parts by weight.

Preferably, the thickness of the corona layer is 4-8% of the thickness of the BOPP film, the thickness of the core layer is 75-80% of the thickness of the BOPP film, and the thickness of the heat sealing layer is 15-20% of the thickness of the BOPP film.

Preferably, the melt index of the homopolypropylene is from 2.5 to 3.5g/10 min.

Preferably, the random silica has two particle size ranges of 1-2 μm and 2-4 μm, wherein the weight ratio of the random silica having a particle size of 1-2 μm to the random silica having a particle size of 2-4 μm is 0.5-1.5: 3.5-4.5.

Preferably, the glass microspheres have a particle size of 2-4 μm.

Preferably, the high heat seal strength puncture resistant BOPP film has a thickness of 20-50 μm.

The invention also provides a preparation method of the high heat-seal-strength puncture-resistant BOPP film, which comprises the following steps:

s1, extruding, plasticizing and melting the core layer raw materials to obtain a core layer melt; heating and melting a corona layer raw material to obtain a corona layer melt; heating and melting the heat seal layer raw material to obtain a heat seal layer melt;

s2, respectively filtering the corona layer melt, the core layer melt and the heat seal layer melt, converging and extruding the melts at a lip of a three-layer die head to form a membrane, attaching the membrane to a chill roll by a high-pressure air knife to be quenched to form a cast sheet, and cooling and shaping the cast sheet by circulating cooling water;

s3, longitudinally stretching the casting sheet to obtain a thick film, transversely stretching, heat setting, and naturally cooling to room temperature to obtain the puncture-resistant BOPP film with high heat-seal strength, wherein during longitudinal stretching, the preheating temperature of the corona layer is 150-.

Preferably, in S3, the preheating temperature for transverse stretching is 175-180 ℃, the transverse stretching temperature is 155-160 ℃, and the transverse stretching multiple is 8-10 times.

Preferably, in S3, the heat-setting temperature is 165-170 ℃.

Preferably, in S2, the screen is 400 mesh and the pressure of the high pressure air knife is 260 bar.

And in the step S3, introducing the high-heat-seal-strength puncture-resistant BOPP film into a traction system for flattening, measuring the thickness by a beta-ray thickness gauge, and rolling to obtain a finished product.

The core layer of the invention adopts the homopolymerized polypropylene, the erucamide slipping agent and the SBS styrene thermoplastic elastomer, thereby improving the impact resistance, puncture resistance and opening effect of the film; the anti-adhesion master batch A for shallow screen printing with smaller granularity is selected for the corona layer, so that the film printing applicability is strong, and the printing problems of point loss, poor overprinting and the like can be avoided; the heat sealing layer adopts metallocene ternary copolymer polypropylene, linear low-density polyethylene and anti-sticking master batch B, so that the BOPP film has good heat sealing performance and lower initial heat sealing temperature; the invention provides a proper preparation method according to the BOPP film, and the corona layer and the heat-sealing layer are preheated at different temperatures during longitudinal stretching so as to prevent the heat-sealing layer from being stuck on a roller; the BOPP film can also be suitable for the production line of common BOPP films.

The heat sealing strength of the invention can reach more than 20N/15mm, the pendulum impact resistance (strength) can be more than or equal to 1.0J, and the friction coefficient is less than or equal to 0.3; the puncture resistance is more than or equal to 1.5N/mum, the invention can replace part of PE or CPP composite package, and has wide market prospect.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.