Co-extruded packaging material for hot-filling and method of manufacture and use

Abstract

This invention relates to the field of food packaging, specifically to a co-extruded packaging material for hot filling, its preparation method, and its application. The co-extruded packaging material is a co-extruded film, which consists of seven layers from the outside in: a first layer of random copolymer polypropylene, a second layer of adhesive resin, a third layer of copolymer nylon, a fourth layer of adhesive resin, a fifth layer of copolymer nylon, a sixth layer of adhesive resin, and a seventh layer of polyethylene. The polyethylene layer is composed of 55-65 wt% metallocene linear polyethylene, 32-42 wt% linear low-density polyethylene, and 2.6-3.7 wt% additive masterbatch. The co-extruded packaging material provided by this invention exhibits stable packaging performance, good flatness, and excellent heat resistance, meeting drop performance requirements. This co-extruded packaging material can prevent wrinkles in the heat-sealed area after hot filling and cooling at room temperature, and prevent bag breakage during hot filling drops, meeting the packaging needs of the market and customers.

Description

Technical Field

[0001] This invention relates to the field of food packaging, specifically to a co-extruded packaging material for hot filling, its preparation method, and its application. Background Technology

[0002] Pre-prepared foods are a type of healthy, nutritious, and convenient food processed using modern technology without altering the original physical properties of the ingredients. As a fast-moving food category with diverse consumer demands, they greatly facilitate people's lives, eliminating the complicated preparation process of cooking. Consumers can consume pre-prepared foods simply by heating or processing them. There are various production and processing methods for pre-prepared foods, as well as diverse filling methods. Hot filling is a high-temperature filling method where, after the product undergoes UHT instantaneous sterilization, it is recirculated and filled through the outlet of the food storage tank at a constant temperature of 90-110℃. For products using hot filling, the requirements for packaging materials are very high, posing significant performance challenges.

[0003] Currently, high-temperature filling mostly uses conventional retort pouches as packaging materials. Common materials used in the structure of conventional retort pouches include biaxially oriented polyester film (BOPET), aluminum foil (Al), and retort-grade cast polypropylene film (CPP), which offer advantages such as high barrier properties and retortability. However, when using retort pouches (BOPET / Al / RCPP structure) in food hot-fill projects, issues have arisen such as wrinkles in the heat-sealed area after cooling to room temperature and pouch breakage during drop tests. Using the conventional retort pouch structure as packaging material cannot meet market and customer demands.

[0004] The technical problem to be solved is to provide a packaging material that, while maintaining the performance of hot filling, prevents wrinkles in the heat-sealed area after cooling at room temperature and prevents bags from breaking due to drops. Summary of the Invention

[0005] In order to solve the problems in the prior art, one of the objectives of the present invention is to provide a co-extruded packaging material for hot filling.

[0006] The technical solution adopted in this invention is as follows:

[0007] A co-extruded packaging material for hot filling, the co-extruded packaging material being a co-extruded film, the co-extruded film comprising seven layers from the outside in: a first layer of random copolymer polypropylene, a second layer of adhesive resin, a third layer of copolymer nylon, a fourth layer of adhesive resin, a fifth layer of copolymer nylon, a sixth layer of adhesive resin, and a seventh layer of polyethylene; the polyethylene layer being composed of 55-65 wt% metallocene linear polyethylene, 32-42 wt% linear low-density polyethylene, and 2.6-3.7 wt% additive masterbatch.

[0008] Preferably, the additive masterbatch is composed of open-cell masterbatch and slip masterbatch in a mass ratio of 1:1.

[0009] Preferably, the first layer uses 100wt% Nordic Chemicals grade RB707CF random copolymer polypropylene; the second layer uses LyondellBasell Industries grade PX3838 adhesive resin; the third layer uses BASF AG grade C40L09 copolymer nylon; the fourth layer uses LyondellBasell Industries grade PX3747 adhesive resin; the fifth layer uses BASF AG grade C40L09 copolymer nylon; the sixth layer uses LyondellBasell Industries grade PX3747 adhesive resin; and in the seventh layer, the metallocene linear polyethylene is Mitsui Chemicals grade SP3210 polyethylene, and the linear low-density polyethylene is Dow Chemicals grade 2038.68G polyethylene.

[0010] Preferably, the open-end masterbatch is Mitsui Chemicals' EAZ-10 open-end masterbatch, and the slip masterbatch is Anposite colorimetric 10090-K slip masterbatch.

[0011] Preferably, the mass ratio of the metallocene linear polyethylene, linear low-density polyethylene, open-cell masterbatch and slip masterbatch is 60:37:1.5:1.5.

[0012] Preferably, the total thickness of the co-extruded film is 100-120 μm, and the thickness ratio of the first to the seventh layer is (23-27):(7-9):(13-17):(6-8):(13-17):(7-9):(30-34).

[0013] Preferably, the total thickness of the co-extruded film is 110 μm, and the thicknesses of the first to seventh layers are 25 μm, 8 μm, 15 μm, 7 μm, 15 μm, 8 μm, and 32 μm, respectively.

[0014] A second objective of this invention is to provide a method for producing the aforementioned co-extruded packaging material for hot filling, comprising the following steps:

[0015] S1. The raw materials for the first to seventh layers of the co-extruded packaging material are prepared in proportion and then put into the mixer for uniform mixing. They are then fed into the extruder for melting.

[0016] S2. Following the arrangement of the first to seventh layers, co-extrude blown film using an extruder, and obtain the required co-extruded packaging material through steps such as blown film expansion and traction, clamping and defoaming, corona treatment, edge trimming and film winding.

[0017] Preferably, the inflation ratio of the inflation traction is 2.

[0018] The present invention also provides the use of the co-extruded packaging material for hot filling as described above in the preparation of packaging materials for hot-filled products.

[0019] The present invention also provides a packaging material for hot-fill products, wherein the packaging material uses the co-extruded packaging material for hot filling as described in any one of claims 1-6.

[0020] The beneficial effects of this invention are as follows:

[0021] Products using hot-fill technology have very high requirements for packaging materials. Using conventional high-temperature retort pouches as packaging materials results in wrinkles in the heat-sealed area after hot filling and cooling at room temperature, as well as bag breakage due to hot filling drops, which cannot meet market and customer needs.

[0022] The co-extruded packaging material provided by this invention has a seven-layer structure. The first layer (outer layer) is a polypropylene layer, which uses the random copolymer polypropylene RB707CF from Borealis. RB707CF is a random copolymer polypropylene resin based on Borealis's Nordic Polymerization Technology. It has excellent heat resistance, high stiffness, processing performance, and good mechanical properties, and can be processed and produced using blown film technology.

[0023] The second layer is an adhesive resin layer, using LyondellBasell Industries PX3838. PX3838 serves as the adhesive layer, exhibiting excellent adhesion to both polypropylene and copolynylated nylon. In the adhesive resin, maleic anhydride monomers form functional branches on the polypropylene backbone. These branches can rapidly and efficiently react chemically with the polar resin, forming covalent and hydrogen bonds, thus bonding the polar and non-polar polymers together.

[0024] The third and fifth layers are both copolymer nylon layers. The thickness of the nylon layer has a significant impact on the mechanical properties and drop resistance of the packaging material. If the thickness is too thin, the physical and mechanical properties of the film are not ideal; if the thickness is too thick, the performance is better, but the amount of nylon resin used will increase, resulting in higher costs. The copolymer nylon used in this invention is C40L09 produced by BASF AG, Germany. It has advantages and characteristics such as high oxygen barrier properties, good moisture resistance, excellent aroma retention, strong mechanical properties, high drop resistance, puncture resistance, and good tear resistance, thus balancing thickness with mechanical properties.

[0025] The fourth and sixth layers are both adhesive resin layers, using LyondellBasell Industries PX3747. PX3747, as an adhesive layer, provides bonding performance between the two nylon layers. In this adhesive resin, the functional branches formed by maleic anhydride monomers on the polyethylene main chain can rapidly react chemically with the polar resin to form covalent and hydrogen bonds, thus bonding the polar and non-polar polymers together.

[0026] The seventh layer is a modified polyethylene layer, composed of special metallocene linear polyethylene, linear low-density polyethylene, and additive open-cell masterbatch and slip masterbatch.

[0027] Metallocene linear polyethylene (MLPE) is made from Mitsui Chemicals SP3210. Adding this grade allows the film to simultaneously achieve rigidity, heat resistance, and impact strength, resulting in a good balance of heat resistance, high rigidity, and high impact strength. Linear low-density polyethylene (LLDPE) is made from Dow Chemical 2038.68G, which possesses good mechanical strength, excellent heat-sealing strength, and superior processing performance. When blended with SP3210, it exhibits good processing properties, enabling the film to possess heat resistance, high rigidity, and high impact strength, while also exhibiting excellent anti-fouling and heat-sealing properties.

[0028] The co-extruded packaging material provided by this invention is used for hot filling, exhibiting stable packaging performance, good flatness, and excellent heat resistance during hot filling, meeting drop performance requirements. This co-extruded packaging material can prevent wrinkles in the heat-sealed area after cooling to room temperature and prevent bag breakage during hot filling drops, thus addressing the performance requirements of packaging materials for hot-filled food products and meeting the packaging needs of the market and customers. Attached Figure Description

[0029] Figure 1 This is a structural schematic diagram of the co-extruded packaging material for hot filling provided by the present invention.

[0030] The meanings of the symbols marked in the figure are as follows:

[0031] A - First floor B - Second floor C - Third floor D - Fourth floor

[0032] E - Fifth Floor F - Sixth Floor G - Seventh Floor Detailed Implementation

[0033] The technical solution of the present invention will be described below with reference to the accompanying drawings and embodiments, so as to enable those skilled in the art to understand it.

[0034] like Figure 1 As shown, a co-extruded packaging material for hot filling is a co-extruded film consisting of seven layers from the outside in:

[0035] The first layer, A, is a random copolymer polypropylene layer, composed of 100 wt% of Borealis brand RB707CF random copolymer polypropylene; the second layer, B, is an adhesive resin layer, composed of 100 wt% of LyondellBasell Industries brand PX3838 adhesive resin; the third layer, C, is a copolymer nylon layer, composed of 100 wt% of BASF brand C40L09 copolymer nylon; the fourth layer, D, is an adhesive resin layer, composed of 100 wt% of LyondellBasell Industries brand PX3747 adhesive resin; the fifth layer, E, is a copolymer nylon layer, composed of 100 wt% of BASF brand C40L09 copolymer nylon; the sixth layer, F, is an adhesive resin layer. The first layer consists of 100 wt% LyondellBasell Industries PX3747 adhesive resin; the seventh layer G is a polyethylene layer, composed of 55-65 wt% metallocene linear polyethylene, 32-42 wt% linear low-density polyethylene and 2.6-3.7 wt% additive masterbatch, the metallocene linear polyethylene is Mitsui Chemicals SP3210 polyethylene and the linear low-density polyethylene is Dow Chemicals 2038.68G polyethylene; the additive masterbatch is composed of open-face masterbatch and slip masterbatch in a 1:1 mass ratio, the open-face masterbatch is Mitsui Chemicals EAZ-10 open-face masterbatch and the slip masterbatch is Anpei Color 10090-K slip masterbatch.

[0036] The preferred mass ratio of the above-mentioned metallocene linear polyethylene, linear low-density polyethylene, open-cell masterbatch and slip masterbatch is 60:37:1.5:1.5.

[0037] As shown in Table 1, the total thickness of the co-extruded film is 100-120 μm, and the thickness ratio of the first layer A to the seventh layer G is (23-27):(7-9):(13-17):(6-8):(13-17):(7-9):(30-34).

[0038] Table 1. Formulations of co-extruded packaging materials for hot filling.

[0039]

[0040] The preparation method of the above co-extruded packaging material includes the following steps:

[0041] S1. The raw materials for the first to seventh layers of the co-extruded packaging material are prepared in proportion and then put into the mixer for uniform mixing. They are then fed into the extruder for melting.

[0042] S2. Following the arrangement of the first to seventh layers, co-extrusion blow molding is performed using an extruder with a blow ratio of 2.0. The desired co-extruded packaging material is obtained through blow traction, clamp defoaming, corona treatment, edge trimming, and film winding.

[0043] The product was manufactured using a seven-layer co-extrusion blow molding machine of model VAREX manufactured by W&H GmbH in Germany. Three sets were prepared and are referred to as Examples 1-3, as shown in Table 2.

[0044] Table 2 Comparison of raw material formulations for each layer in Examples 1-3

[0045]

[0046] Comparative example:

[0047] A conventional high-temperature retort packaging bag material was used for comparison. It consists of a three-layer composite of biaxially oriented polyester film (BOPET), aluminum foil (Al), and retort-grade cast polypropylene film (CPP), with a material structure of 12μm BOPET / 7μm Al / 80μm ​​CPP. After laminating the 12μm thick BOPET with the 7μm thick Al (aluminum foil), a second layer was formed with the 80μm thick CPP film to obtain the composite film. Performance tests were performed on the composite film, and the results are compared with those of Examples 1-3 of this invention, as shown in Table 3.

[0048] Table 3 Technical Specifications of Examples 1-3 and Comparative Examples

[0049]

[0050]

[0051] As can be seen from the test results in the table above, the co-extruded packaging material for hot filling produced using the preparation process of this invention, through a special functional formulation design and the application of multi-layer co-extrusion processing technology and production technology, achieves innovative applications of food hot filling packaging materials. It can ensure stable packaging performance while maintaining the hot filling performance, has good flatness, and exhibits excellent heat resistance during hot filling, meeting drop performance requirements. It prevents wrinkles in the heat-sealed area after cooling at room temperature and avoids bag breakage due to hot filling drops, thus solving the performance requirements of food hot filling packaging materials and meeting the packaging needs of the market and customers.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A co-extruded packaging material for hot filling, wherein the co-extruded packaging material is a co-extruded film, characterized in that, The co-extruded film consists of seven layers from the outside in: the first layer is a random copolymer polypropylene layer, the second layer is an adhesive resin layer, the third layer is a copolymer nylon layer, the fourth layer is an adhesive resin layer, the fifth layer is a copolymer nylon layer, the sixth layer is an adhesive resin layer, and the seventh layer is a polyethylene layer; the polyethylene layer is composed of 55~65wt% metallocene linear polyethylene, 32~42wt% linear low-density polyethylene, and 2.6~3.7wt% additive masterbatch; The first layer uses 100wt% Nordic Chemicals grade RB707CF random copolymer polypropylene; the second layer uses LyondellBasell Industries grade PX3838 adhesive resin; the third layer uses BASF AG grade C40L09 copolymer nylon; the fourth layer uses LyondellBasell Industries grade PX3747 adhesive resin; the fifth layer uses BASF AG grade C40L09 copolymer nylon; the sixth layer uses LyondellBasell Industries grade PX3747 adhesive resin; in the seventh layer, the metallocene linear polyethylene is Mitsui Chemicals grade SP3210 polyethylene, and the linear low-density polyethylene is Dow Chemicals grade 2038.68G polyethylene.

2. The co-extruded packaging material for hot filling as described in claim 1, characterized in that, The additive masterbatch is composed of open-cell masterbatch and slip masterbatch in a mass ratio of 1:

1.

3. The co-extruded packaging material for hot filling as described in claim 2, characterized in that, The open-end masterbatch is Mitsui Chemicals' EAZ-10 open-end masterbatch, and the slip masterbatch is Anposite colorimetric 10090-K slip masterbatch.

4. A co-extruded packaging material for hot filling as described in claim 2, characterized in that, The mass ratio of the metallocene linear polyethylene, linear low-density polyethylene, open-cell masterbatch and slip masterbatch is 60:37:1.5:1.

5.

5. A co-extruded packaging material for hot filling as described in claim 2, characterized in that, The total thickness of the co-extruded film is 100~120 μm, and the thickness ratio of the first to the seventh layer is (23~27): (7~9): (13~17): (6~8): (13~17): (7~9): (30~34).

6. A co-extruded packaging material for hot filling as described in claim 2, characterized in that, The total thickness of the co-extruded film is 110 μm, and the thicknesses of the first to seventh layers are 25 μm, 8 μm, 15 μm, 7 μm, 15 μm, 8 μm, and 32 μm, respectively.

7. A method for producing a co-extruded packaging material for hot filling as described in any one of claims 1-6, characterized in that, The steps are as follows: S1. The raw materials for the first to seventh layers of the co-extruded packaging material are prepared in proportion and then put into a mixer to be mixed evenly, and then fed into an extruder to be melted separately; S2. Following the arrangement of the first to seventh layers, co-extrude blown film using an extruder, and obtain the desired co-extruded packaging material through steps of blown film expansion and traction, clamping and defoaming, corona treatment, edge trimming and film winding; the blown film expansion ratio of the blown film expansion and traction is 2.

8. The use of the co-extruded packaging material for hot filling as described in any one of claims 1-6 in the preparation of packaging materials for hot-fill products.

9. A packaging material for hot-fill products, characterized in that, The packaging material used is a co-extruded packaging material for hot filling as described in any one of claims 1-6.

Images