All-PP octagonal sealed coffee bags and their preparation

Abstract

This invention provides a fully PP eight-side seal coffee bag and its preparation method. The method includes the following steps: S1, providing a biaxially oriented polypropylene film and a polypropylene film, wherein the biaxially oriented polypropylene film is formed by mixing, extruding, biaxially oriented, cooling and shaping, cutting and printing 25-35 parts by weight of polypropylene, 65-75 parts by weight of propylene-styrene block copolymer, 0.5-2 parts by weight of slip agent and 1-5 parts by weight of opening agent; the polypropylene film is composed of a corona layer, an intermediate layer and a heat-sealing layer, and is formed by extrusion, curing, cooling and corona treatment processes; S2, bonding the biaxially oriented polypropylene film and the polypropylene film with adhesive to form a composite film; S3, after the composite film is made into a bag, heat-sealing it with an accordion hot air knife.

Description

Technical Field

[0001] This invention relates to a fully PP eight-side sealed coffee bag and its preparation. Background Technology

[0002] While plastic products bring convenience to people's lives, they also cause long-term harm to the environment. Because plastics are not easily decomposed, plastic waste, if not recycled, will become pollutants in the environment, accumulating and causing significant damage. Many existing eight-side seal packaging products are multi-layered composite structures of different plastics, offering high performance but with complex material structures that cannot be recycled. To ensure product performance and ease of production, the product structures are often made of PET, aluminum foil, or metallized materials, facilitating the normal production of materials in existing equipment.

[0003] Existing eight-side seal bags are mostly made of PET / AL / PE, PET / VMPET / PE, PET / PE, etc. These structures have simple manufacturing processes and require minimal pre-processing of the materials, but they are very difficult to recycle, as effective separation of the products is impossible, ultimately leading to their disposal and long-term environmental pollution. BOPP / CPP composite film is a new material that can be recycled without separation, and it holds promise for use in eight-side seal bags. However, compared to PET, BOPP in existing BOPP / CPP composite films has poorer temperature resistance. The high-temperature heat treatment during bag making can damage the BOPP material, causing it to stick to the heat treatment blade. When the temperature drops, it leads to insufficient airtightness. Summary of the Invention

[0004] This invention provides a fully PP eight-side sealed coffee bag and its preparation method, which can effectively solve the above-mentioned problems.

[0005] This invention is implemented as follows:

[0006] This invention provides an all-PP eight-side seal coffee bag, which is composed of biaxially oriented polypropylene film and polypropylene film composite. The polypropylene film consists of a corona layer, an intermediate layer, and a heat-sealing layer. The biaxially oriented polypropylene film is composed of 25 to 35 parts by weight of polypropylene, 65 to 75 parts by weight of propylene-styrene block copolymer, 0.5 to 2 parts by weight of slip agent, and 1 to 5 parts by weight of opening agent.

[0007] The present invention further provides a method for preparing an all-PP eight-side seal coffee bag, comprising the following steps: S1, providing a biaxially oriented polypropylene film and a polypropylene film, wherein the biaxially oriented polypropylene film is formed by mixing, extruding, biaxially oriented, cooling and shaping, cutting and printing 25 to 35 parts by weight of polypropylene, 65 to 75 parts by weight of propylene-styrene block copolymer, 0.5 to 2 parts by weight of slip agent and 1 to 5 parts by weight of opening agent; the polypropylene film is composed of a corona layer, an intermediate layer and a heat-sealing layer, and is formed by extrusion, curing, cooling and corona treatment processes;

[0008] S2, a composite film is formed by bonding biaxially oriented polypropylene film and polypropylene film together with adhesive.

[0009] S3, after the composite film is made into a bag, it is heat-sealed with a gusseted hot air knife.

[0010] The beneficial effects of this invention are as follows: By improving the biaxially oriented polypropylene film (printed layer), this invention solves the technical problem that biaxially oriented polypropylene film is easily damaged under high-temperature conditions and sticks to the knife. Furthermore, the all-PP eight-side seal coffee bag provided by this invention can replace existing eight-side seal bag products with structures such as PET / AL / PE, PET / VMPET / PE, and PET / PE, thus solving the technical problem that existing eight-side seal bag products require effective separation for recycling, or are not recyclable at all. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0012] Figure 1 This is a flowchart illustrating the preparation method of the all-PP eight-side sealed coffee bag provided in this embodiment of the invention.

[0013] Figure 2 and 3 This is a photo of the all-PP eight-side sealed coffee bag provided in an embodiment of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Please participate (button) Figure 2-3 As shown, this invention provides a fully PP eight-side sealed coffee bag, comprising: a biaxially oriented polypropylene film and a polypropylene film composite, wherein the polypropylene film consists of a corona layer, an intermediate layer, and a heat-sealing layer, and the biaxially oriented polypropylene film is composed of 25-35 parts by weight of polypropylene, 65-75 parts by weight of propylene-styrene block copolymer, 0.5-2 parts by weight of slip agent, and 1-5 parts by weight of opening agent. The polypropylene can be of type F1002. The propylene-styrene block copolymer can be of type SEPTON 8004. The slip agent can be oxidized polyethylene wax, oxidized polyethylene wax paste, oxidized polyethylene wax, silicone masterbatch, polyolefin wax, or other types of slip agents, which are not limited herein. The opening agents are mainly mineral-based and organic-based. Mineral-based opening agents include talc, diatomaceous earth, etc., while organic-based opening agents include oleamide, erucamide, and EBS derivatives, etc. The amount of these opening agents added can be selected according to actual needs and applications to improve the opening performance and anti-blocking performance of the film.

[0016] In existing technologies, BOPP film is generally composed of polypropylene and a certain amount of slip agent. However, this ratio can cause the BOPP material to be damaged by the high-temperature heat exchanger during bag making, resulting in sticking to the heat exchanger. When the temperature decreases, the airtightness fails to meet requirements. This invention creatively incorporates an propylene-styrene block copolymer (i.e., some polypropylene is replaced by the propylene-styrene block copolymer), thereby solving the problem of the high-temperature heat exchanger damaging the BOPP material during bag making. Preferably, the biaxially oriented polypropylene film is composed of 28 to 32 parts by weight of polypropylene, 68 to 72 parts by weight of propylene-styrene block copolymer, 0.8 to 1.5 parts by weight of slip agent, and 2 to 3 parts by weight of opening agent. In one embodiment, more preferably, the biaxially oriented polypropylene film is composed of 30 parts by weight of polypropylene, 71 parts by weight of propylene-styrene block copolymer, 1.2 parts by weight of slip agent, and 2.5 parts by weight of opening agent.

[0017] As a further improvement, to enhance the heat-sealing effect of the composite film, this invention further refines the polypropylene film. This is because the seal is worst at the gusset overlap during heat sealing, resulting in substandard product airtightness. This problem can be solved by increasing the bag-making temperature and pressure, or by decreasing the heat-sealing temperature; however, increasing the temperature damages the BOPP surface, causing the film to become sticky and break. Therefore, the only solution is to decrease the film's heat-sealing temperature.

[0018] As a further improvement, to reduce the temperature of the heat-sealing layer, the materials of the heat-sealing layer in this embodiment of the invention are further improved. Specifically, the heat-sealing layer is composed of 65 to 75 parts by weight of styrene-ethylene-propylene block copolymer, 25 to 35 parts by weight of ethylene-propylene random copolymer, 1 to 5 parts by weight of metallocene PP, 2 to 5 parts by weight of slip agent, and 1 to 5 parts by weight of opening agent. The styrene-ethylene-propylene block copolymer is SEPTON 1020; the ethylene-propylene random copolymer is ExxonMobil APP-199, 299, 399, etc. The metallocene PP can be Yanshan Petrochemical's MU4016. The heat-sealing temperature of existing CPP generally reaches 170°C or even above 180°C, while this invention, through the addition of metallocene PP, can significantly reduce its heat-sealing temperature to about 150-60°C, and give it good heat-sealing strength, with a heat-sealing strength of over 50N at 150°C. Preferably, the heat-sealing layer comprises 68-72 parts by weight of styrene-ethylene-propylene block copolymer, 28-32 parts by weight of ethylene-propylene random copolymer, 3-4 parts by weight of metallocene PP, 3-4 parts by weight of slip agent, and 2-3 parts by weight of opening agent. In one embodiment, the heat-sealing layer comprises 70 parts by weight of styrene-ethylene-propylene block copolymer, 30 parts by weight of ethylene-propylene random copolymer, 3 parts by weight of metallocene PP, 4 parts by weight of slip agent, and 2 parts by weight of opening agent. The corona layer can use existing filled polypropylene resins, such as F800EDF, R140M, FC-150B, HF4008, and F703 polypropylene resins; the intermediate layer material can be FC801, HF400, HF420, FC-150J, etc. Experiments have shown that when the addition amount of metallocene PP reaches about 3 wt%, the heat-sealing strength of the material reaches its limit, and further addition of metallocene PP does not significantly change the heat-sealing strength.

[0019] Please see Figure 1 As shown in the figure, this embodiment of the invention further provides a method for preparing a full PP eight-side sealed coffee bag, including the following steps:

[0020] S1 provides a biaxially oriented polypropylene film and a polypropylene film, wherein the biaxially oriented polypropylene film is formed by mixing, extruding, biaxially oriented, cooling and shaping, cutting and printing 25 to 35 parts by weight of polypropylene, 65 to 75 parts by weight of propylene-styrene block copolymer, 0.5 to 2 parts by weight of slip agent and 1 to 5 parts by weight of opening agent; the polypropylene film is composed of a corona layer, an intermediate layer and a heat-sealing layer, and is formed by extrusion, curing, cooling and corona treatment processes.

[0021] S2, a composite film is formed by bonding biaxially oriented polypropylene film and polypropylene film together with adhesive.

[0022] S3, after the composite film is made into a bag, it is heat-sealed with a gusseted hot air knife.

[0023] In step S1, the extrusion, biaxial stretching, cooling and shaping, cutting, printing, curing, cooling and corona treatment are all existing technologies and will not be described in detail here.

[0024] In step S3, the parameters for heat sealing using a bellows-style hot air knife are as follows: heat sealing temperature 150-170℃, pressure 0.35-0.45MPa, and heat sealing time 0.1-1s. More preferably, the parameters for heat sealing using a bellows-style hot air knife are as follows: 155-165℃, pressure 0.38-0.42MPa, and heat sealing time 0.3-1s. In other embodiments, the heat sealing temperatures are 150℃, 152℃, 155℃, 158℃, 160℃, 162℃, 165℃, 168℃, and 170℃, respectively.

[0025] Example 1:

[0026] 30 parts by weight of F1002 polypropylene, 71 parts by weight of SEPTON propylene-styrene block copolymer, 1.2 parts by weight of oxidized polyethylene wax, and 2.5 parts by weight of talc are mixed, extruded, biaxially stretched, cooled and shaped, cut, and printed to form a biaxially stretched polypropylene film with a thickness of approximately 20 micrometers.

[0027] A polypropylene film with a thickness of approximately 40 micrometers is formed by extruding, curing, cooling, and corona treatment of 70 parts by weight of SEPTON 1020 styrene-ethylene-propylene block copolymer, 30 parts by weight of APP-199 ethylene-propylene random copolymer, 3 parts by weight of MU4016 metallocene PP, 4 parts by weight of oxidized polyethylene wax, 2 parts by weight of talc to form a heat-sealing layer, FC801 material intermediate layer, and F800EDF material corona layer.

[0028] The above-mentioned biaxially oriented polypropylene film is laminated with polypropylene film using an inorganic adhesive and a laminating machine to form a composite film. Finally, the composite film is made into a bag and then heat-sealed with an accordion hot air knife, and the heat seal strength is tested.

[0029] Test Example 1: The tensile strength, breaking strength, and tear strength of the final composite film were tested according to GB13022 and QB / T1130 standards, respectively. The data are as follows: The tensile strength of the composite film is 340 MPa in the transverse direction and 460 MPa in the longitudinal direction; the elongation at break in the transverse direction is 110% and the elongation at break in the longitudinal direction is 85%; the tear strength is 145 N / mm in the transverse direction and 215 N / mm in the longitudinal direction.

[0030] Test Example 2: On a heat seal strength tester, a full PP eight-side seal coffee bag was heat-sealed, then stretched at a certain speed until it broke. The maximum force during the stretching process was recorded, and the heat seal strength was calculated. The unit of heat seal strength is Newtons (N). In the heat seal test, each temperature was tested in parallel three times, and the average value was taken as shown in Table 1. The surface of the bag was also visually inspected to see if it was damaged by a heat gun.

[0031] Table 1 is a test data record table for the embodiment.

[0032]

[0033] As shown in Table 1, the heat seal strength reaches 50.5 N when the temperature increases to 150℃, which basically meets the requirements. With further temperature increases, the heat seal strength reaches a peak of approximately 58.0 N, but there is no significant increase in heat seal strength with further temperature increases. Furthermore, as the temperature reaches approximately 170℃, slight defects such as burns from a heat gun begin to appear on the surface of the bag.

[0034] Test Example 3: Finally, drop tests (100g*1.5m) were conducted on products with heat sealing temperatures of 150℃, 160℃ and 170℃. The bags did not break after 3 drops, which is considered qualified and meets customer requirements. The data is shown in Table 2.

[0035] Table 2 shows the drop test data for Example 1.

[0036] Heat sealing temperature (°C) Is it qualified? 150 No (1) 155 yes 160 yes 165 yes 170 yes

[0037] As can be seen from Table 2 above, the heat sealing strength at 150℃ is slightly insufficient, and the bag broke once in 4 drop tests, while the heat sealing temperature above 155℃ can fully meet the requirements.

[0038] Single-factor experiment - Example 2:

[0039] The results were basically the same as in Example 1, except that the number of parts of MU4016 metallocene PP content were adjusted to 1 part, 2 parts, 4 parts and 5 parts, and bags were made from them respectively and heat-sealing strength was tested at 160°C, as shown in Table 3.

[0040] Table 3 shows the heat seal strength data for different metallocene PP contents.

[0041]

[0042]

[0043] As can be seen from Table 3, the addition of metallocene PP can form a good synergistic effect with other materials, which can significantly improve the heat sealing strength. However, as the amount added reaches 5 parts, its effect reaches its limit and there is no significant change.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A fully PP eight-side sealed coffee bag, characterized in that, include: The product is composed of biaxially oriented polypropylene film and polypropylene film composite, wherein the polypropylene film comprises a corona layer, an intermediate layer, and a heat-sealing layer. The product is characterized in that: the biaxially oriented polypropylene film comprises 25-35 parts by weight of polypropylene, 65-75 parts by weight of propylene-styrene block copolymer, 0.5-2 parts by weight of slip agent, and 1-5 parts by weight of opening agent; the heat-sealing layer comprises 65-75 parts by weight of styrene-ethylene-propylene block copolymer, 25-35 parts by weight of ethylene-propylene random copolymer, 1-5 parts by weight of metallocene PP, 2-5 parts by weight of slip agent, and 1-5 parts by weight of opening agent.

2. The all-PP eight-side sealed coffee bag as described in claim 1, characterized in that, The biaxially oriented polypropylene film is composed of 28 to 32 parts by weight of polypropylene, 68 to 72 parts by weight of propylene-styrene block copolymer, 0.8 to 1.5 parts by weight of slip agent, and 2 to 3 parts by weight of opening agent.

3. The all-PP eight-side sealed coffee bag as described in claim 2, characterized in that, The biaxially oriented polypropylene film is composed of 30 parts by weight of polypropylene, 71 parts by weight of propylene-styrene block copolymer, 1.2 parts by weight of slip agent, and 2.5 parts by weight of opening agent.

4. The all-PP eight-side sealed coffee bag as described in claim 1, characterized in that, The heat-sealing layer consists of 68 to 72 parts by weight of styrene-ethylene-propylene block copolymer, 28 to 32 parts by weight of ethylene-propylene random copolymer, 3 to 4 parts by weight of metallocene PP, 3 to 4 parts by weight of slip agent, and 2 to 3 parts by weight of opening agent.

5. The all-PP eight-side sealed coffee bag as described in claim 1, characterized in that, The heat-sealing layer consists of 70 parts by weight of styrene-ethylene-propylene block copolymer, 30 parts by weight of ethylene-propylene random copolymer, 3 parts by weight of metallocene PP, 4 parts by weight of slip agent, and 2 parts by weight of opening agent.

6. A method for preparing a fully PP eight-side sealed coffee bag, characterized in that, Includes the following steps: S1 provides a biaxially oriented polypropylene film and a polypropylene film, wherein the biaxially oriented polypropylene film is formed by mixing, extruding, biaxially oriented, cooling and shaping, cutting and printing 25-35 parts by weight of polypropylene, 65-75 parts by weight of propylene-styrene block copolymer, 0.5-2 parts by weight of slip agent and 1-5 parts by weight of opening agent; the polypropylene film is composed of a corona layer, an intermediate layer and a heat-sealing layer, and is formed by extrusion, curing, cooling and corona treatment processes; the heat-sealing layer is composed of 65-75 parts by weight of styrene-ethylene-propylene block copolymer, 25-35 parts by weight of ethylene-propylene random copolymer, 1-5 parts by weight of metallocene PP, 2-5 parts by weight of slip agent and 1-5 parts by weight of opening agent. S2, a composite film is formed by bonding biaxially oriented polypropylene film and polypropylene film together with adhesive. S3, after the composite film is made into a bag, it is heat-sealed with a gusseted hot air knife.

7. The method for preparing a full PP eight-side sealed coffee bag as described in claim 6, characterized in that, The parameters for heat sealing using a bellows hot air knife are as follows: temperature 150-170℃, pressure 0.35-0.45MPa, and heat sealing time 0.1-1s.

8. The method for preparing a full PP eight-side sealed coffee bag as described in claim 7, characterized in that, The temperature is 155-165℃, the pressure is 0.38-0.42MPa, and the heat sealing time is 0.3-1s.

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