A foldable heat-sealable composite packaging material and its preparation method

Abstract

The present invention relates to a foldable heat-sealable composite packaging material and a preparation method thereof, belonging to the technical field of packaging. The packaging material is a composite film, and the composite film from the outside to the inside is successively: a coating, a BOPET layer, a paper layer, an Al layer, and a PP layer. The coating is compounded with the BOPET layer through a gravure coating process. The corona layer comprises 80 parts by mass of polypropylene homopolymer resin and 20 parts by mass of terpolymerized polypropylene; the intermediate layer comprises 100 parts by mass of polypropylene homopolymer resin; the heat-sealing layer comprises 40-50 parts by mass of polypropylene homopolymer resin, 50-60 parts by mass of terpolymerized polypropylene, 0.9-1.1 parts by mass of a slip masterbatch, 0.9-1.1 parts by mass of an antiblocking masterbatch, and 0.1-0.2 parts by mass of a processing aid. The preparation method of the present invention realizes the innovative application of the foldable heat-sealable composite packaging material through the application of special functional formula design, specific processing technology, and packaging composite technology, bringing a novel packaging form to product packaging.

Description

Technical Field

[0001] The present invention relates to the field of packaging, and in particular to a foldable heat-sealable composite packaging material and a preparation method thereof. Background Art

[0002] Product packaging plays a crucial role in aspects such as product storage, transportation, sales, and safety guarantee. First of all, the barrier property of the packaging can prevent the erosion of sunlight, air, and moisture, prevent the deliquescence and oxidation of products, and at the same time maintain the due luster, flavor, and form of the products; secondly, the advertising effect of the packaging plays an important role in the product sales process. A novel and unique packaging can attract the attention of consumers, stimulate the purchase desire of target consumers, and improve the perceived value of the packaged products; thirdly, the packaging ensures the hygienic safety of the product from production, transportation, shelf to the hands of the final consumer, and plays the role of a food safety guard in preventing microbial and dust pollution.

[0003] With the continuous increase in the types and quantities of packaged products, especially the demand for food packaging, and the continuous improvement of consumers' tastes and appreciation levels, higher and more requirements are also put forward for the form of product packaging, while conventional flexible packaging materials cannot achieve a foldable packaging form. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a foldable heat-sealable composite packaging material and a preparation method thereof, and the packaging material has foldability.

[0005] In order to achieve one of the purposes of the present invention, the following technical solutions are adopted in the present invention:

[0006] A foldable heat-sealable composite packaging material, the packaging material is a composite film, and the composite film from outside to inside is in turn: a coating, a BOPET layer, a paper layer, an Al layer, and a PP layer. The coating is compounded with the BOPET layer through an intaglio coating process. The corona layer of the PP layer is connected to the AL layer. The PP layer is made by coextrusion casting of a corona layer, an intermediate layer, and a heat-sealing layer; the corona layer includes 70-80 parts by mass of polypropylene homopolymer resin and 20-30 parts by mass of terpolymerized polypropylene; the intermediate layer includes 100 parts by mass of polypropylene homopolymer resin; the heat-sealing layer includes 30-40 parts by mass of polypropylene homopolymer resin, 60-70 parts by mass of terpolymerized polypropylene, 0.9-1.1 parts by mass of a slip masterbatch, 0.9-1.1 parts by mass of an antiblocking masterbatch, and 0.1-0.2 parts by mass of a processing aid.

[0007] Preferably, the coating is a heat-sealing coating, and the one used is HSL1202 produced by Bostik Findley Adhesives Co., Ltd.

[0008] Preferably, the thickness ratio of the corona layer, the intermediate layer and the heat-pressing layer is 2:5:3; the grade of the homopolypropylene resin is HD905CF produced by Borealis; the grade of the terpolymerized polypropylene is FL7632L produced by TPC Polyolefins (Singapore) Pte., Ltd.; the grade of the slip masterbatch is 10090-K produced by Ampacet; the grade of the anti-blocking masterbatch is AB20LD produced by Beijing Yalong; the grade of the processing aid is 100991-K produced by Ampacet.

[0009] Preferably, the corona layer comprises 75 parts by mass of homopolypropylene resin and 25 parts by mass of terpolymerized polypropylene; the intermediate layer comprises 100 parts by mass of homopolypropylene resin; the heat-sealing layer comprises 35 parts by mass of homopolypropylene resin, 65 parts by mass of terpolymerized polypropylene, 1.0 part by mass of slip masterbatch, 1.0 part by mass of anti-blocking masterbatch and 0.15 part by mass of processing aid.

[0010] The second object of the present invention is to provide a preparation method of a foldable heat-sealable composite packaging material, and the preparation method comprises the following steps:

[0011] S1. According to the resin raw material formula, add the heat-sealing layer resin raw material, the intermediate layer resin raw material and the corona layer resin raw material into the three barrels of the co-extrusion casting equipment respectively; co-extrude the raw materials in the three barrels and then enter the casting station for cooling and shaping, and then corona-treat the surface of the corona layer of the cast and shaped film to obtain a cast PP film, that is, the PP layer of the composite film;

[0012] S2. Coat the coating liquid on the surface of the BOPET film by gravure coating through the coating equipment, and wind it up after drying in the drying oven to form a heat-sealing coating / BOPET film;

[0013] S3. Dryly laminate the heat-sealing coating / BOPET film in step S2 with paper and AL in sequence to form a heat-sealing coating / BOPET / paper / AL, and then laminate the PP layer in step S1 on the AL side of the once-laminated heat-sealing coating / BOPET / paper / AL composite film through a dry lamination process, and finally obtain a composite packaging material with a foldable heat-sealable heat-sealing coating / BOPET / paper / AL / PP structure.

[0014] Preferably, in step S1, the temperatures of the three barrels corresponding to the extruder barrels are all: the first stage: 225 - 235 °C, the second stage: 235 - 245 °C, the third stage: 240 - 250 °C; the die head temperature is 235 - 245 °C; the temperature of the casting roll surface in the casting station is 25 °C, and the power of the corona treatment is 35 - 37 Wmin / m 2 and the pressure of the corona roll is 6 - 7 bar.

[0015] Preferably, in step S2, the coating wire roller is an intaglio printing cylinder with 90 - 100 lines per inch, having a copper layer and chrome - plated on the surface. The wet coating amount is 5 - 6 g / m², and the dry coating amount is 1.0 - 1.2 g / m². In the coating process, the temperature of the drying oven is: the first stage is 70 - 75°C, the second stage is 75 - 80°C, and the third stage is 80 - 85°C.

[0016] Preferably, in step S3, the adhesive used for dry lamination is a two - component polyurethane adhesive, with the brand number YH8950 produced by Beijing GaoMeng Company.

[0017] Preferably, in step S2, the thickness of the heat - seal coating is 1 - 1.5 μm.

[0018] Preferably, the paper is food - grade packaging base paper.

[0019] The beneficial effects of the present invention compared with the prior art are as follows:

[0020] (1) The present invention provides a foldable heat - sealable composite packaging material and its preparation method. In addition to meeting the basic functions such as packaging protection, barrier property, and display property, this foldable heat - sealable composite packaging material also has foldability, making the packaging material more convenient to open, safer, having better packaging conformability, better display effect after being made into a packaging product, and having less usage of packaging materials under the same packaging capacity.

[0021] (2) The present invention applies special functional formula design, specific processing technology, and packaging lamination technology. Specifically, by selecting the types of paper, Al layer, and PP layer particles in the packaging material, the obtained packaging material has foldability. By intaglio - coating a heat - sealable coating on the outer surface layer, the outer surface of the packaging material has heat - sealability, realizing the innovative application of the foldable heat - sealable composite packaging material and bringing a novel packaging form to product packaging.

[0022] (3) The heat-sealing coating of the present invention is achieved on the surface of BOPET through a local coating process. The coating thickness is 1 - 1.5 μm, enabling the outer surface of the packaging material to have heat-sealing properties. Local coating can be carried out during the preparation of the packaging material according to customer requirements, so that the packaging material only has heat-sealing properties on the outer surface of the parts that need to be folded, facilitating the outward folding and heat-sealing of the packaging material. The heat-sealing coating uses HSL1202 produced by Bostik Findley Adhesives Co., Ltd. This coating solution has characteristics such as high heat-sealing strength and a wide heat-sealing temperature range; the BOPET layer is mainly used as a substrate and can be printed with various color patterns according to requirements; it also has high temperature resistance and can meet the requirements of high-speed printing. The paper layer has properties such as light weight, non-rebound, foldability, and easy processing, and also has characteristics such as strong display function and comfortable touch; the aluminum foil (Al) layer can block the entry of water vapor, oxygen, and light in the air, and at the same time block the penetration of the components of the contents in the composite film packaging, having excellent barrier properties and fragrance retention properties, and also having a certain foldability, providing a certain folding performance for the packaging material.

[0023] (4) In the present invention, the grade of the polypropylene homopolymer resin is HD905CF produced by Borealis AG, and the particles have high rigidity and high stiffness properties, which can further improve the foldable stability of the whole product; the grade of the terpolymer polypropylene is FL7632L produced by TPC Polyolefins (Singapore) Pte. Ltd., which has good fluidity, low heat-sealing temperature, high transparency, a high degree of molecular orientation, good thermal stability and heat-resistant sealing properties, and excellent processing properties. Brief Description of the Drawings

[0024] Figure 1 is the flow chart of the present invention. Detailed Description of the Invention

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further details the present invention in conjunction with the drawings and embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0026] The packaging material is a composite film, which from the outside to the inside in turn is: a coating, a BOPET layer, a paper, an Al layer and a PP layer. The coating is compounded with the BOPET layer through a gravure coating process. The PP layer is made by co-extrusion casting of a corona layer, an intermediate layer and a heat-sealing layer. The corona layer includes 80 parts by mass of polypropylene homopolymer resin and 20 parts by mass of terpolymerized polypropylene. The intermediate layer includes 100 parts by mass of polypropylene homopolymer resin. The heat-sealing layer includes 40 - 50 parts by mass of polypropylene homopolymer resin, 50 - 60 parts by mass of terpolymerized polypropylene, 0.9 - 1.1 parts by mass of a slip masterbatch, 0.9 - 1.1 parts by mass of an anti-blocking masterbatch and 0.1 - 0.2 parts by mass of a processing aid. The corona layer of the PP layer is connected to the Al layer.

[0027] The preparation method includes the following steps:

[0028] S1. According to the resin raw material formula, add the resin raw materials for the heat-sealing layer, the intermediate layer and the corona layer into three barrels of the co-extrusion casting equipment respectively. Co-extrude the raw materials in the three barrels and then enter the casting station for cooling and shaping. Then, corona-treat the surface of the corona layer of the shaped film to obtain a cast PP film, which is the PP layer of the composite film.

[0029] S2. Coat the surface of the BOPET film with a coating solution through a coating equipment, and wind it up after drying in a drying oven to form a heat-sealing coating / BOPET film.

[0030] S3. Dry-compound the heat-sealing coating / BOPET film in step S2 with the paper and the AL in turn to form a heat-sealing coating / BOPET / paper / AL. Then, compound the PP layer in step S1 to the AL surface of the first-compounded heat-sealing coating / BOPET / paper / AL composite film through a dry-compounding process to finally obtain a composite packaging material with a heat-sealing coating / BOPET / paper / AL / PP structure that can be folded and heat-sealed.

[0031] In step S1, the temperatures of the three barrels corresponding to the extruder barrels are all: the first stage: 230 °C, the second stage: 240 °C, the third stage: 245 °C; the die head temperature is 240 °C; the temperature of the casting roller surface in the casting station is 25 °C, the power of the corona treatment is 36 Wmin / m2, and the corona roller pressure is 6 bar.

[0032] In step S2, the coating gravure roller is a gravure roller with 90 - 100 lines per inch, having a copper layer and a chromium-plated surface. The wet coating amount is 5 - 6 g / m2, and the dry coating amount is 1.0 - 1.2 g / m2. The temperature of the drying oven in the coating process is: the first stage 70 °C, the second stage 75 °C, the third stage 80 °C.

[0033] In step S3, the adhesive used for dry lamination is a two-component polyurethane adhesive, supplied by Beijing GaoMeng, with the brand name YH8950.

[0034] This preparation method utilizes special functional formula design. Through specific processing techniques and the application of packaging lamination technology, the innovative application of a foldable heat-sealable composite packaging material is achieved. The preparation method includes the following steps: cast film production process, coating process, and dry lamination process.

[0035] Among them, the cast modified polypropylene film is made by co-extrusion casting of three layers: a corona layer, an intermediate layer, and a heat-sealing layer. The thickness ratio of the corona layer, the intermediate layer, and the hot-pressing layer is 2∶5∶3.

[0036] In the following examples, the homopolymer polypropylene resin is HD905CF produced by Borealis; the terpolymer polypropylene is FL7632L produced by TPC Polyolefins (Singapore) Pte. Ltd.; the slip masterbatch is 10090-K produced by Ampacet; the antiblocking masterbatch is AB20LD produced by Beijing Yalong; the processing aid is 100991-K produced by Ampacet. The temperatures of the three barrels of the extruder are all: the first section: 230°C, the second section: 240°C, the third section: 245°C, and the die head temperature: 240°C; in the casting process, the surface temperature of the casting roll is set at 25°C, and the cast and shaped film is corona-treated on the surface of its corona layer. The corona treatment power is set at 36Wmin / m 2 and the corona roll pressure is 6 bar. After corona treatment, the cast PP film is obtained. The coating used is Estersol HSL1202 produced by Bostik Findley Adhesives Co., Ltd.

[0037] Example 1

[0038] S1. Weigh 225 parts by mass of homopolymer polypropylene resin; 75 parts by mass of terpolymer polypropylene; 1.0 part of slip masterbatch; 1.0 part by mass of antiblocking masterbatch; 0.15 part by mass of processing aid. Distribute the resin raw materials of the heat-sealing layer, the intermediate layer, and the corona layer with the allocated formula weight parts into the extruder, and after co-extrusion, cool and shape at the casting station;

[0039] S2. Corona-treat the surface of the cast and shaped film on its corona layer to obtain a modified PP film;

[0040] S3. Through the coating process, coat the coating liquid on the surface of the BOPET film by gravure coating, and after drying in the drying oven, wind it up to form a heat-sealing coating / BOPET film.

[0041] S4. Dry laminate the BOPET film coated with the coating layer with paper and AL to form heat-sealing coating / BOPET / paper / AL. Finally, laminate the inner modified PP film on the inner surface of the once-laminated heat-sealing coating / BOPET / paper / AL composite film through a dry lamination process, ultimately forming a foldable heat-sealable composite packaging material with a coating / BOPET / paper / AL / modified PP structure.

[0042] Example 2

[0043] S1. Weigh 220 parts by mass of homopolypropylene resin; 80 parts by mass of terpolymerized polypropylene; 0.9 part of slip masterbatch; 0.9 part by mass of antiblocking masterbatch; 0.10 part by mass of processing aid. Distribute the raw materials of the heat-sealing layer resin, intermediate layer resin, and corona layer resin in the assigned formula weight parts into an extruder, and after co-extrusion, cool and shape it at the casting station.

[0044] S2. Corona-treat the surface of the film after casting and shaping on its corona layer to obtain a modified PP film.

[0045] S3. Through the coating process, apply the coating liquid to the surface of the BOPET film by gravure coating, and after drying in the drying oven, wind it up to form a heat-sealing coating / BOPET film.

[0046] S4. Dry laminate the BOPET film coated with the coating layer with paper and AL to form heat-sealing coating / BOPET / paper / AL. Finally, laminate the inner modified PP film on the inner surface of the once-laminated heat-sealing coating / BOPET / paper / AL composite film through a dry lamination process, ultimately forming a foldable heat-sealable composite packaging material with a coating / BOPET / paper / AL / modified PP structure.

[0047] Example 3

[0048] S1. Weigh 230 parts by mass of homopolypropylene resin; 70 parts by mass of terpolymerized polypropylene; 1.1 parts of slip masterbatch; 1.1 parts by mass of antiblocking masterbatch; 0.2 part by mass of processing aid. Distribute the raw materials of the heat-sealing layer resin, intermediate layer resin, and corona layer resin in the assigned formula weight parts into an extruder, and after co-extrusion, cool and shape it at the casting station.

[0049] S2. Corona-treat the surface of the film after casting and shaping on its corona layer to obtain a modified PP film.

[0050] S3. Through the coating process, apply the coating liquid to the surface of the BOPET film by gravure coating, and after drying in the drying oven, wind it up to form a heat-sealing coating / BOPET film.

[0051] S4. Dry laminate the BOPET film coated with the coating layer with paper and AL to form heat-sealing coating / BOPET / paper / AL. Finally, laminate the inner modified PP film on the inner surface of the once-laminated coating / BOPET / paper / AL composite film through a dry lamination process, ultimately forming a foldable heat-sealable composite packaging material with a heat-sealing coating / BOPET / paper / AL / modified PP structure.

[0052] Comparative Example 1

[0053] S1. Weigh 150 parts by mass of homopolypropylene resin; 150 parts by mass of terpolymerized polypropylene; 1.0 part of a slip masterbatch; 1.0 part by mass of an antiblocking masterbatch; 0.15 part by mass of a processing aid. Distribute the raw materials of the heat-sealing layer resin, the intermediate layer resin, and the corona layer resin with the assigned formula weight parts into an extruder, and after co-extrusion, cool and shape at a casting station.

[0054] S2. Perform corona treatment on the surface of the corona layer of the film after casting and shaping.

[0055] S3. Dry laminate the BOPET film with paper and AL to form BOPET / paper / AL. Finally, laminate the prepared PP film on the inner surface of the once-laminated BOPET / paper / AL composite film through a dry lamination process, ultimately forming a composite packaging material with a BOPET / paper / AL / PP structure.

[0056] Perform performance tests on the packaging materials prepared in Examples 1 - 3 and Comparative Example 1, and the results are shown in Table 1 below:

[0057] Table 1

[0058]

[0059]

[0060] As can be seen from the test results in Table 1, the outer layer heat-sealing strength of the packaging materials prepared in Examples 1-3 is 4.5-4.6 N / 15 mm, and the folding resilience is 2 for all of them. The packaging material prepared in Comparative Example 1 has no outer layer heat-sealing strength, and the folding resilience is 26. This shows that the heat-sealing coating / BOPET / paper / AL / modified PP structure composite film prepared by the preparation process of the present invention has the surface heat-sealing performance that ordinary composite packaging materials do not have. The folding resilience performance of the composite packaging material produced by the special formula and process is much greater than that of the ordinary packaging materials produced from the same materials at present, indicating that it has excellent and stable fold resistance performance and excellent surface heat-sealing performance, enabling the innovative application of the foldable heat-sealable composite packaging material, bringing a novel packaging form to product packaging. In addition to meeting the basic functions such as packaging protection, barrier property, and display property, this foldable heat-sealable composite packaging also has the characteristics of convenient opening, high safety, good packaging conformability, and excellent display effect, and is favored by consumers and food enterprises.

[0061] The thin film material of the present invention is manufactured by the casting process based on the selection of particles, the design of the formula, and the optimization of the process, so that the thin film packaging material exhibits high rigidity, high stiffness, fold resistance, impact resistance, pressure resistance, and excellent stability for subsequent reprocessing under normal or high temperature conditions.

[0062] Those skilled in the art should understand that the above are only several specific embodiments of the present invention, rather than all embodiments. It should be pointed out that many modifications and improvements can be made by those of ordinary skill in the art. All modifications or improvements that do not exceed the scope of the claims shall be regarded as the protection scope of the present invention.

Claims

1. A foldable heat-sealable composite packaging material, characterized in that, The packaging material is a composite film, and the composite film from outside to inside is successively: a coating layer, a BOPET layer, a paper layer, an Al layer and a PP layer. The coating layer is compounded with the BOPET layer through a gravure coating process. The corona layer of the PP layer is connected to the AL layer. The PP layer is made by co-extrusion casting of three layers including a corona layer, an intermediate layer and a heat-sealing layer. The corona layer includes 70-80 parts by mass of polypropylene homopolymer resin and 20-30 parts by mass of ethylene-propylene-diene terpolymer. The intermediate layer includes 100 parts by mass of polypropylene homopolymer resin. The heat-sealing layer includes 30-40 parts by mass of polypropylene homopolymer resin, 60-70 parts by mass of ethylene-propylene-diene terpolymer, 0.9-1.1 parts by mass of a slip masterbatch, 0.9-1.1 parts by mass of an anti-blocking masterbatch and 0.1-0.2 parts by mass of a processing aid. The coating layer is a heat-sealing coating layer.

2. The foldable heat-sealable composite packaging material according to claim 1, wherein The heat-sealing coating layer uses HSL1202 produced by Bostik Findley Adhesives Co., Ltd.

3. The foldable heat-sealable composite packaging material according to claim 1, wherein, The thickness ratio of the corona layer, the intermediate layer and the hot-pressing layer is 2∶5∶3. The polypropylene homopolymer resin is HD905CF produced by Borealis Chemical Company. The ethylene-propylene-diene terpolymer is FL7632L produced by TPC Polyolefins (Singapore) Pte., Ltd. The slip masterbatch is 10090-K produced by Ampacet Corporation. The anti-blocking masterbatch is AB20LD produced by Beijing Yalong Company. The processing aid is 100991-K produced by Ampacet Corporation.

4. The foldable heat-sealable composite packaging material according to claim 3, wherein, The corona layer includes 75 parts by mass of polypropylene homopolymer resin and 25 parts by mass of ethylene-propylene-diene terpolymer. The intermediate layer includes 100 parts by mass of polypropylene homopolymer resin. The heat-sealing layer includes 35 parts by mass of polypropylene homopolymer resin, 65 parts by mass of ethylene-propylene-diene terpolymer, 1.0 part by mass of a slip masterbatch, 1.0 part by mass of an anti-blocking masterbatch and 0.15 part by mass of a processing aid.

5. A method for preparing a foldable heat-sealable composite packaging material according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: S1. According to the resin raw material formula, add the resin raw materials of the heat-sealing layer, the intermediate layer and the corona layer into three barrels of a co-extrusion casting device respectively. Co-extrude the raw materials in the three barrels and then enter the casting station for cooling and shaping. Then, corona-treat the surface of the corona layer of the shaped film to obtain a cast PP film, that is, the PP layer of the composite film. S2. Coating liquid is coated on the surface of a BOPET film through a coating device by gravure coating, and is wound after drying in a drying oven to form a heat-sealing coating layer / BOPET film. S3. The heat-sealing coating layer / BOPET film in step S2 is successively dry-compounded with the paper and the AL to form a heat-sealing coating layer / BOPET / paper / AL. Then, the PP layer in step S1 is compounded on the AL surface of a composite film of a first-layer heat-sealing coating layer / BOPET / paper / AL through a dry-compounding process, and finally a composite packaging material with a heat-sealing coating layer / BOPET / paper / AL / PP structure that can be folded and heat-sealed is prepared.

6. The preparation method of the foldable heat-sealable composite packaging material according to claim 5, wherein, In the step S1, the temperatures of the three barrels corresponding to the barrel of the extruder are all as follows: the first stage: 225 - 235 °C, the second stage: 235 - 245 °C, the third stage: 240 - 250 °C; the temperature of the die head is 235 - 245 °C; the temperature of the surface of the casting roll in the casting station is 25 °C, and the power of the corona treatment is 35 - 37 Wmin / m 2 , and the pressure of the corona roll is 6 - 7 bar.

7. The preparation method of the foldable heat-sealable composite packaging material according to claim 5, characterized in that, In the step S2, the coating wire roller is an intaglio printing roller with 90 - 100 lines per inch, having a copper layer and a chrome - plated surface. The wet coating amount is 5 - 6 g / m², and the dry coating amount is 1.0 - 1.2 g / m². In the coating process, the temperature of the drying oven is: 70 - 75°C in the first stage, 75 - 80°C in the second stage, and 80 - 85°C in the third stage.

8. The preparation method of the foldable heat-sealable composite packaging material according to claim 5, characterized in that, In the step S3, the adhesive used for dry lamination is a two - component polyurethane adhesive, with the brand number YH8950 produced by Beijing GaoMeng Company.

9. The preparation method of the foldable heat-sealable composite packaging material according to claim 5, wherein In the step S2, the thickness of the heat - seal coating is 1 - 1.5 μm.

10. The preparation method of the foldable heat-sealable composite packaging material according to claim 5, wherein, The paper is a food - grade packaging base paper.

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