A high-crystallinity paper-based multi-dimensional composite food packaging material and its preparation method

Abstract

The present invention relates to the field of paper-based packaging materials, and discloses a paper-based multi-dimensional composite food packaging material with high crystallinity, which includes a back coating, a direct aluminized layer, a first barrier coating, a base paper layer, a second barrier coating, an adhesive layer, a transfer aluminized layer, a transfer release layer, and a heat-sealing coating, which are sequentially arranged from bottom to top. It also discloses its preparation method, which includes the following steps: coating the transfer release layer on a PET film to form a pre-coated film, and aluminizing the coating side of the pre-coated film after drying to form a transfer aluminized film; coating the first barrier coating and the second barrier coating on both sides of the base paper layer to form a base paper, and aluminizing the first barrier coating side of the base paper after drying to form a direct aluminized base paper; using the adhesive layer to adhere the second barrier coating surface of the direct aluminized base paper to the aluminum surface of the transfer aluminized film, and stripping off the PET film in line after drying; coating the back coating and the heat-sealing coating on the direct aluminized layer surface and the transfer release layer surface respectively. The material of the present invention has multi-dimensional barrier functions and strong anti-damage ability.

Description

Technical Field

[0001] The invention relates to the field of paper-based packaging materials, and in particular to a high-crystallinity paper-based multi-dimensional composite food packaging material and a preparation method thereof. Background Art

[0002] Plastic packaging has always been favored for its advantages such as lightness, durability, low cost and excellent barrier properties. However, plastic packaging materials generally have the difficulties of high recycling costs, difficulty in natural degradation and dependence on non-renewable resources such as petroleum. Years of abuse have also caused considerable pollution to the environment. In contrast, paper-based materials have significant advantages in environmental protection. The main materials of paper-based packaging materials are mostly from renewable resources, which shows that paper-based packaging materials are naturally renewable, degradable and recyclable. Environmentally friendly properties, at the same time, the fiber structure of paper-based materials also makes its surface suitable for printing without too much secondary surface treatment. This situation has prompted the public to increasingly prefer paper-based materials to replace plastic packaging materials. However, the porous fiber structure of paper gives paper strong hygroscopicity and gas permeability, which makes the barrier properties of conventional paper-based packaging materials poor. Therefore, the development of environmentally friendly paper-based materials with excellent barrier properties has become a hot research topic in the packaging materials industry.

[0003] The mainstream products of paper-based packaging materials at present include aluminum foil barrier paper, paper-plastic composite paper, transfer barrier paper and conventional direct-plated paper. Aluminum foil barrier paper requires a large amount of aluminum, which has high production costs and is difficult to recycle later; the production of paper-plastic composite paper requires the use of plastic substrates, and plastic materials are difficult to degrade naturally in the environment, have a long degradation cycle, and are prone to environmental pollution. Conventional direct-plated paper and transfer aluminum-plated paper can meet cost and environmental protection requirements, but both are not foldable and the aluminum layer is easily damaged, which will lead to a decrease in the barrier properties of the product. Summary of the invention

[0004] In view of the above-mentioned shortcomings that currently exist, the present invention provides a high-crystallinity paper-based multi-dimensional composite food packaging material and a preparation method thereof, which can enable the paper-based packaging material to have a multi-dimensional barrier function, greatly improving the damage resistance of the paper-based packaging material. The material has the characteristics of being plastic-free, high-barrier, heat-sealable, degradable, and directly contactable with food, meeting the requirements of green and environmentally friendly design. The material has high moisture and oxygen barrier properties, can effectively extend the shelf life of the packaged products, and has high production efficiency.

[0005] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0006] A high-crystallinity paper-based multi-dimensional composite food packaging material comprises a back coating, a direct aluminum plating layer, a first barrier coating, a base paper layer, a second barrier coating, an adhesive layer, a transfer aluminum layer, a transfer release layer, and a heat-sealing coating which are arranged in sequence from bottom to top.

[0007] According to one aspect of the present invention, both the first barrier coating and the second barrier coating are made of waterborne acrylic coatings, with a solid content of 39% and a viscosity of 20 s, and the sizing amount is 3.5 g / m 2 ~4 g / m 2 .

[0008] According to one aspect of the present invention, both the direct aluminized layer and the transferred aluminized layer are formed by vapor deposition technology, and the thickness of both is 48 nm to 52 nm.

[0009] According to one aspect of the present invention, the transfer release layer uses a food-grade transfer coating material, with a solid content of 15%, a viscosity of 25 s, and the dry coating amount is 1.15 g / m 2 , and the thermal efficiency is 74.

[0010] According to one aspect of the present invention, the back coating uses a waterborne environmental protection coating, with a solid content of 21.1%, a viscosity of 11 s, and the sizing amount is 3.5 g / m 2 ~4 g / m 2 ; the heat-sealing coating uses a waterborne acrylic heat-sealing coating, with a solid content of 36±2% and a viscosity of 12±3 s, and the sizing amount is 5.5 g / m 2 ~6 g / m 2 .

[0011] According to one aspect of the present invention, the adhesive layer uses a waterborne acrylic glue, with a solid content of 45%, a viscosity of 35 s, and the composite sizing amount is 5.5 g / m 2 ~6 g / m 2 .

[0012] According to one aspect of the present invention, the base paper layer uses a single-sided coated food-grade glassine paper, and its grammage range is 30 g / m 2 ~100 g / m 2 .

[0013] A preparation method of a high-crystallinity paper-based multi-dimensional composite food packaging material includes the following steps:

[0014] Coat the transfer release layer on the PET film to form a pre-coated film, and after drying, aluminize the coated side of the pre-coated film to form a transferred aluminized film;

[0015] Coat the first barrier coating and the second barrier coating on both sides of the base paper layer to form a base paper, and after drying, aluminize the first barrier coating side of the base paper to form a directly aluminized base paper;

[0016] Use the adhesive layer to adhere the second barrier coating side of the directly aluminized base paper to the aluminum surface of the transferred aluminized film, and after drying, strip off the PET film in-line;

[0017] The back coating and the heat-sealing coating are respectively coated on the directly aluminized layer and the transfer release layer.

[0018] According to one aspect of the present invention, the PET film is a biaxially oriented polyester film. After the pre-coated film is dried, it is placed in a vacuum aluminizing machine to aluminize the coating side to form a transfer aluminized film. After the base paper is dried, it is placed in a vacuum aluminizing machine to aluminize the first barrier coating side to form a directly aluminized base paper. The adhesive layer is adhered through a wet laminating machine.

[0019] According to one aspect of the present invention, the coating dry weight of the transfer release layer is 1.15 g / m 2 、heat effect 74. The aluminum layer thickness of both the transfer aluminized film and the directly aluminized base paper is 48 nm to 52 nm. The sizing amount of the adhesive layer is 5.5 g / m 2 ~6 g / m 2 , the sizing amount of the back coating is 3.5 g / m 2 ~4 g / m 2 , the sizing amount of the heat-sealing coating is 5.5 g / m 2 ~6 g / m 2 .

[0020] Advantages of the implementation of the present invention: Through the composite design of the directly aluminized layer, the transfer aluminized layer and the barrier coating, the material has multi-dimensional barrier functions, greatly improving the anti-damage ability of the paper-based packaging material. This material combines the characteristics of being plastic-free, highly barrier, heat-sealable, degradable, and directly food-contactable, meeting the requirements of green environmental protection design; this material has high moisture and oxygen barrier properties, which can effectively extend the shelf life of the packaged products; Step 1 and Step 2 in the production of this material can be carried out simultaneously, reducing the waiting time for working hours and having high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is a schematic structural diagram of the high-crystallinity paper-based multi-dimensional composite food packaging material described in the present invention.

[0023] The names corresponding to the serial numbers in the figure are as follows:

[0024] 1. Back coating; 2. Directly aluminized layer; 3. First barrier coating; 4. Base paper layer; 5. Second barrier coating; 6. Adhesive layer; 7. Transfer aluminized layer; 8. Transfer release layer; 9. Heat-sealing coating. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "top", "bottom", "one side", "the other side", "front", "rear", "middle part", "inside", "top end", "bottom end", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0026] Embodiment 1

[0027] As Figure 1 shown, a high-crystallinity paper-based multi-dimensional composite food packaging material includes a back coating 1, a direct aluminized layer 2, a first barrier coating 3, a base paper layer 4, a second barrier coating 5, an adhesive layer 6, a transfer aluminized layer 7, a transfer release layer 8, and a heat-sealing coating 9, which are sequentially arranged from bottom to top. The preparation method of the high-crystallinity paper-based multi-dimensional composite food packaging material includes the following steps:

[0028] Coat the transfer release layer 8 on a PET film to form a pre-coated film. After drying, aluminize the coated side of the pre-coated film to form a transfer aluminized film;

[0029] Coat the first barrier coating 3 and the second barrier coating 5 on both sides of the base paper layer 4 to form a base paper. After drying, aluminize the side of the base paper with the first barrier coating 3 to form a direct aluminized base paper;

[0030] Use the adhesive layer 6 to adhere the side of the direct aluminized base paper with the second barrier coating 5 to the aluminized side of the transfer aluminized film. After drying, strip off the PET film in-line;

[0031] Coat the back coating 1 and the heat-sealing coating on the side of the direct aluminized layer 2 and the side of the transfer release layer 8 respectively.

[0032] In this embodiment, the back coating 1 uses a water-based environmentally friendly coating with a solid content of 21.1% and a viscosity of 11 s (coat 4 cup, room temperature), and the sizing amount is 3.5 g / m 2 ~4 g / m 2 ; the back coating 1 can provide certain protection for the direct aluminized layer 2, reduce scratches and abrasions, and at the same time can improve the surface tension of the direct aluminized layer 2, making it have higher printing adaptability.

[0033] In this embodiment, both the direct aluminized layer 2 and the transferred aluminized layer 7 are formed by vapor deposition technology, which endows them with excellent airtightness and can effectively block the penetration of oxygen and moisture; the thickness of both aluminized layers is 48 nm to 52 nm.

[0034] In this embodiment, the first barrier coating 3 and the second barrier coating 5 are the same type of barrier coating, with the same structural materials. Both use water-based acrylic coatings, with a solid content of 39% and a viscosity of 20 s (Ford cup, room temperature), and the sizing amount is 3.5 g / m 2 ~4 g / m 2 ; the barrier coating ensures excellent moisture and oxygen barrier properties. After the barrier coating penetrates into the base paper layer 4, it can effectively improve the crystallinity of paper fiber molecules and increase the ordered micro-region space of the paper, significantly reducing the adsorption of water molecules to hydroxyl groups and the transmission of oxygen molecules in the paper fiber structure, thus possessing excellent moisture and oxygen barrier properties; at the same time, after being filled with the first barrier coating 3, the surface of the base paper layer 4 can become smoother, which is beneficial to the formation of the direct aluminized layer 2.

[0035] In this embodiment, the base paper layer 4 uses a single-sided coated food-grade glassine paper, which has a higher cohesive energy density and a lower fiber structure pore diameter after supercalendering treatment, can effectively prevent the transmission of oxygen molecules in the paper, and at the same time, the smoother and more even paper surface is also beneficial to the formation of the direct aluminized layer 2; the optional grammage range of the base paper layer 4 is 30 g / m 2 ~100 g / m 2 .

[0036] In this embodiment, the adhesive layer 6 uses water-based acrylic glue, with a solid content of 45% and a viscosity of 35 s (Ford cup, room temperature), which is used to connect the base paper layer 4 and the transferred aluminized layer 7, and the composite sizing amount is 5.5 g / m 2 ~6 g / m 2 .

[0037] In this embodiment, the transfer release layer 8 uses a food-grade transfer coating material, with a solid content of 15% and a viscosity of 25 s (Ford cup, room temperature), and the coating dry weight is 1.15 g / m 2 , and the heat effect is 74.

[0038] In this embodiment, the heat-sealing coating uses a water-based acrylic heat-sealing coating, with a solid content of 36 ± 2% and a viscosity of 12 ± 3 s, and the sizing amount is 5.5 g / m 2 ~6 g / m 2 ; the heat-sealing coating can provide stable heat-sealing performance for the materials of the present invention, and at the same time, the materials are safe, non-toxic and can be directly contacted with food.

[0039] The beneficial effects of this embodiment are as follows: Through the composite design of the direct aluminized layer 2, the transferred aluminized layer 7, and the barrier coating, the material has multi-dimensional barrier functions, greatly improving the anti-damage ability of the paper-based packaging material. This material combines the characteristics of being plastic-free, having high barrier properties, being heat-sealable, biodegradable, and directly food-contactable, meeting the requirements of green environmental protection design; this material has high moisture and oxygen barrier properties, which can effectively extend the shelf life of the packaged products; Steps 1 and 2 of the production of this material can be carried out synchronously, reducing the waiting time for working hours and having high production efficiency.

[0040] Embodiment 2

[0041] This embodiment provides a preparation method of a high-crystallinity paper-based multi-dimensional composite food packaging material. The preparation method of this high-crystallinity paper-based multi-dimensional composite food packaging material includes the following steps:

[0042] Step 1: Coat the transfer release layer 8 on a PET film, namely a biaxially oriented polyester film (BOPET), to form a pre-coated film. The coating dry weight is 1.15 g / m 2 , with a heat effect of 74. After sufficient drying, place the pre-coated film into a vacuum aluminizing machine to aluminize its coated side to form a transferred aluminized film. The thickness of the aluminum layer (transferred aluminized layer 7) is 48 nm.

[0043] Step 2: (Simultaneously) Use a wet laminating machine to coat the first barrier coating 3 and the second barrier coating 5 on both sides of the base paper layer 4 to form a base paper. After drying, place the base paper into a vacuum aluminizing machine to aluminize its first barrier coating 3 side to form a directly aluminized base paper. The thickness of the aluminum layer (directly aluminized layer 2) is 48 nm.

[0044] Step 3: Use the adhesive layer 6 in a wet laminating machine to bond the second barrier coating 5 side of the directly aluminized base paper to the aluminum side of the transferred aluminized film. The sizing amount is 5.5 g / m 2 ~6 g / m 2 , and after drying in an oven, strip off the PET film in-line.

[0045] Step 4: Coat the back coating 1 and the heat-sealing coating on the directly aluminized layer 2 side and the transfer release layer 8 side respectively. The sizing amount of the back coating 1 is 3.5 g / m 2 ~4 g / m 2 , and the sizing amount of the heat-sealing coating is 5.5 g / m 2 ~6 g / m 2 ; to obtain the final high-crystallinity paper-based multi-dimensional composite food packaging material.

[0046] In this embodiment, the back coating 1 uses a water-based environmentally friendly coating with a solid content of 21.1% and a viscosity of 11 s (Ford cup, room temperature). The back coating 1 can provide certain protection for the direct aluminized layer 2, reducing scratches and wear. At the same time, it can increase the surface tension of the direct aluminized layer 2, making it have higher printing adaptability.

[0047] In this embodiment, both the direct aluminized layer 2 and the transferred aluminized layer 7 are formed by vapor deposition technology, making them have excellent airtightness and effectively blocking the penetration of oxygen and moisture. The thickness of both aluminized layers is 48 nm to 52 nm.

[0048] In this embodiment, the first barrier coating 3 and the second barrier coating 5 are the same type of barrier coating with the same structural materials. Both use water-based acrylic coatings with a solid content of 39% and a viscosity of 20 s (Ford cup, room temperature), and the sizing amount is 3.5 g / m 2 ~4 g / m 2 ; The barrier coating ensures excellent moisture and oxygen barrier properties. After the barrier coating penetrates into the base paper layer 4, it can effectively increase the crystallinity of the paper fiber molecules and increase the ordered micro-region space of the paper, significantly reducing the adsorption of water molecules to hydroxyl groups and the transmission of oxygen molecules in the paper fiber structure, and having excellent moisture and oxygen barrier properties. At the same time, after being filled by the first barrier coating 3, the surface of the base paper layer 4 can become smoother, which is beneficial to the formation of the direct aluminized layer 2.

[0049] In this embodiment, the base paper layer 4 uses a single-sided coated food-grade glassine paper, which has a higher cohesive energy density and a lower fiber structure pore diameter after supercalendering treatment, can effectively prevent the transmission of oxygen molecules in the paper, and at the same time, the smoother and flatter paper surface is also beneficial to the formation of the direct aluminized layer 2. The optional grammage range of the base paper layer 4 is 30 g / m 2 ~100 g / m 2 。

[0050] In this embodiment, the adhesive layer 6 uses a water-based acrylic glue with a solid content of 45% and a viscosity of 35 s (Ford cup, room temperature), which is used to connect the base paper layer 4 and the transferred aluminized layer 7. The transfer release layer 8 uses a food-grade transfer coating material with a solid content of 15% and a viscosity of 25 s (Ford cup, room temperature).

[0051] In this embodiment, the heat-sealing coating uses a water-based acrylic heat-sealing coating with a solid content of 36 ± 2% and a viscosity of 12 ± 3 s. The heat-sealing coating can provide stable heat-sealing performance for the materials of the present invention, and at the same time, the materials are safe, non-toxic and can be directly contacted with food.

[0052] The beneficial effects of this embodiment are as follows:

[0053] 1. The composite design of the direct aluminized layer, the transferred aluminized layer 7, and the barrier coating enables the material to have multi-dimensional barrier functions, greatly improving the anti-damage ability of the paper-based packaging material. Even after the paper is folded and rubbed multiple times, the barrier layer of the paper can still maintain the maximum degree of integrity, ensuring that the barrier property of the paper always remains within the technical standard range.

[0054] 2. The material of the present invention has high moisture and oxygen barrier properties. After repeated detection and verification, its water vapor transmission rate WVTR < 0.5 (38 °C, 90% RH), and its oxygen transmission rate OTR < 3 (23 °C, 50% RH), which can effectively extend the shelf life of the packaged product.

[0055] 3. The combined use of the transfer and direct plating processes results in the production process of the present invention not having much increase compared to the conventional production processes of transfer paper "coating - aluminizing - compounding + top coating + back gluing" and direct plating paper "bottom coating - aluminizing - compounding + top coating + back gluing". Among them, step one and step two can be carried out synchronously, reducing the working hour waiting time and improving the production efficiency.

[0056] As described above, only the specific embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any changes, combinations, or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A high-crystallinity paper-based multi-dimensional composite food packaging material, characterized in that, It includes a back coating (1), a direct aluminized layer (2), a first barrier coating (3), a base paper layer (4), a second barrier coating (5), an adhesive layer (6), a transfer aluminized layer (7), a transfer release layer (8), and a heat-sealing coating (9) which are sequentially arranged from bottom to top; Both the first barrier coating (3) and the second barrier coating (5) are made of water-based acrylic coatings, with a solid content of 39%, a viscosity of 20 s, and a sizing amount of 3.5 g / m 2 ~4 g / m 2 ; Both the direct aluminized layer and the transferred aluminized layer are formed by physical vapor deposition technology, and the thicknesses of both the direct aluminized layer and the transferred aluminized layer are 48 nm to 52 nm.

2. The highly crystalline paper-based multi-dimensional composite food packaging material according to claim 1, wherein The transfer release layer (8) uses a food-grade transfer coating material with a solid content of 15%, a viscosity of 25 s, and a coating dry weight of 1.15 g / m 2 , and a heat effect of 74.

3. The high-crystallinity paper-based multi-dimensional composite food packaging material according to claim 1, characterized in that, The back coating (1) uses a water-based environmentally friendly coating with a solid content of 21.1%, a viscosity of 11 s, and a sizing amount of 3.5 g / m 2 ~4 g / m 2 ; the heat-sealing coating uses a water-based acrylic heat-sealing coating with a solid content of 36 ± 2%, a viscosity of 12 ± 3 s, and a sizing amount of 5.5 g / m 2 ~6 g / m 2 .

4. The high-crystallinity paper-based multi-dimensional composite food packaging material according to claim 1, wherein The adhesive layer (6) uses water-based acrylic glue with a solid content of 45%, a viscosity of 35 s, and a composite sizing amount of 5.5 g / m 2 ~6 g / m 2 .

5. The high-crystallinity paper-based multi-dimensional composite food packaging material according to claim 1, characterized in that The base paper layer (4) is made of single-sided coated food-grade glassine paper, and its grammage ranges from 30 g / m 2 to 100 g / m 2 .

6. A preparation method of a high-crystallinity paper-based multi-dimensional composite food packaging material, characterized in that To prepare the high-crystallinity paper-based multi-dimensional composite food packaging material according to any one of claims 1-5, the following steps are included: Coat the transfer release layer (8) on a PET film to form a pre-coated film. After drying, aluminize the coated side of the pre-coated film to form a transfer aluminized film, i.e., the transfer aluminized layer (7); Coat the first barrier coating (3) and the second barrier coating (5) on both sides of the base paper layer (4) respectively to form a base paper. After drying, aluminize the side of the base paper with the first barrier coating (3) to form a directly aluminized base paper; Use the adhesive layer (6) to adhere the side of the directly aluminized base paper with the second barrier coating (5) to the aluminized side of the transfer aluminized film. After drying, strip off the PET film in-line; Coat the back coating (1) and the heat-sealing coating on the side of the direct aluminized layer (2) and the side of the transfer release layer (8) respectively.

7. The preparation method according to claim 6, characterized in that, The PET film is a biaxially oriented polyester film. After drying, the pre-coated film is placed in a vacuum aluminizing machine to aluminize the coated side to form a transfer aluminized film. After drying, the base paper is placed in a vacuum aluminizing machine to aluminize the side with the first barrier coating (3) to form a directly aluminized base paper. The adhesive layer (6) is subjected to an adhesion operation through a wet laminating machine.

8. The preparation method according to claim 6, characterized in that, The coating dry weight of the transfer release layer (8) is 1.15 g / m 2 , the heat effect is 74, the aluminum layer thickness of both the transfer aluminized film and the direct-coated base paper is 48 nm to 52 nm, and the sizing amount of the adhesive layer (6) is 5.5 g / m 2 ~6 g / m 2 , the sizing amount of the back coating (1) is 3.5 g / m 2 ~4 g / m 2 , the sizing amount of the heat-sealing coating is 5.5 g / m 2 ~6 g / m 2 .

Images