CN114808544B

CN114808544B - High-barrier packaging paper and processing technology thereof

Info

Publication number: CN114808544B
Application number: CN202210486750.9A
Authority: CN
Inventors: 王刚; 谢彬; 贾天宇; 王玉燕; 杨建青
Original assignee: Shandong Jinmai Material Technology Co ltd
Current assignee: Shandong Jinmai Material Technology Co ltd
Priority date: 2022-05-06
Filing date: 2022-05-06
Publication date: 2023-07-14
Anticipated expiration: 2042-05-06
Also published as: CN114808544A

Abstract

The invention relates to high-barrier packaging paper which is characterized by sequentially comprising a back coating, a metal layer, a high-barrier bottom coating II, a raw paper layer, a high-barrier bottom coating I, a transparent medium layer and a top coating from bottom to top; the first high-barrier primer layer and the second high-barrier primer layer are pre-coated on the upper surface and the lower surface of the paper, and water-based high-barrier paint is adopted, and comprises the following components in parts by mass: 30-60 parts of polyvinyl alcohol, 5-20 parts of polyamide, 30-60 parts of ethylene-vinyl alcohol copolymer, 0.5-1.5 parts of zeolite, 0.5-1.5 parts of clay, 0.5-1.5 parts of silicon dioxide and 0.5-1.5 parts of crystallized cellulose. The invention not only has excellent barrier property of the conventional multi-layer aluminum foil film composite material, but also has the environmental protection performance of degradable and recyclable papermaking.

Description

High-barrier packaging paper and processing technology thereof

Technical Field

The invention relates to high-barrier packaging paper and a processing technology thereof, and belongs to the technical field of packaging materials.

Background

At present, in the field of high-barrier packaging materials, plastic packaging materials and paper, plastic and aluminum composite packaging materials are commonly used at home and abroad, and the materials mainly have the following defects due to the adoption of materials such as plastic, aluminum foil and adhesive: 1) Consume a large amount of non-renewable resources; 2) The interlayer of the materials is tightly combined, can not be disassembled and is difficult to recover; 3) Poor degradability and environmental pollution. Taking the example of paper aluminum composite aseptic packages, aseptic packages have been over 65% of the total beverage package in developed countries and grow at rates of 5-10% annually on average. The consumption of the developed countries reaches more than 100 bags, and the consumption of the developed countries is less than 50 bags per year. Such materials consume large amounts of non-renewable resources on the one hand and packaging residues on the other hand cause great pollution to the environment. The amount of waste discarded every year in the world is estimated to be approximately 100 hundred million tons, packaging waste occupies approximately 1/3 of the volume, meanwhile, the materials of many packages are undegradable and remain in the environment for a long time, the waste seriously influences ecological balance, causes great pollution to marine ecology and land environment, and directly threatens survival of human beings and organisms.

The existing environment-friendly paper-based packaging material is a porous fiber structure, so that the original paper is microscopically a material containing holes, the surface is rough, and the holes are difficult to seal by adopting a common coating process. In addition, when food is packed, the food inevitably contacts with hot water vapor or oil gas, and paper layers and coatings are easy to permeate under the action of hot steam, so that the food can be applied to the field with low barrier property requirements.

The direct plating paper belongs to one kind of vacuum aluminized paper, and has the outstanding characteristics that a transfer film is not needed, film materials such as PE (polyethylene) are not needed, the thickness of the aluminum layer is only 0.020-0.040 mu m, the aluminum consumption is only about two percent of that of the composite aluminum foil paper, and the consumption of metal aluminum is greatly reduced. The product is easy to degrade naturally under natural conditions, can be recycled, and is a novel environment-friendly material which accords with the development trends of green, environment protection, low carbon and the like.

In view of the above, it is very important to provide a packaging material which has high barrier property and is environment-friendly and easy to degrade.

Disclosure of Invention

The invention aims to provide high-barrier packaging paper and a processing technology thereof, wherein the packaging paper not only can keep the environment-friendly characteristic of direct plating paper, but also can have the high-barrier characteristic of aluminum foil packaging materials.

In order to solve the problems, the invention adopts the following technical scheme:

the high-barrier packaging paper is characterized in that the layer structure of the high-barrier packaging paper sequentially comprises a back coating, a metal layer, a high-barrier bottom coating II, a raw paper layer, a high-barrier bottom coating I, a transparent medium layer and a top coating from bottom to top;

the first high-barrier primer layer and the second high-barrier primer layer are pre-coated on the upper surface and the lower surface of the paper, and water-based high-barrier paint is adopted, and comprises the following components in parts by mass:

30-60% of polyvinyl alcohol

Polyamide 5-20

Ethylene-vinyl alcohol copolymer 30-60

Zeolite 0.5-1.5

Clay 0.5-1.5

Silica 0.5-1.5

0.5 to 1.5 portions of crystallized cellulose.

The raw paper layer is double-sided coated paper, and the gram weight is 50-80 g/square meter.

The transparent medium adopted by the transparent medium layer is alumina or zinc sulfide.

The metal adopted by the metal layer is aluminum or copper.

The top coat adopts traditional printable polyacrylate system varnish.

The back coating adopts solvent-resistant vinyl chloride copolymer emulsion.

The processing technology of the high-barrier packaging paper is characterized by comprising the following steps of:

s1, double-sided precoating is carried out on the front and back surfaces of paper in a double-sided curtain coating mode, the coating amount of the double-sided precoating is 10-15 g/square meter, and a high-barrier primer layer formed by coating adopts a water-based high-barrier coating and comprises the following raw materials in parts by mass:

30-60% of polyvinyl alcohol

Polyamide 5-20

Ethylene-vinyl alcohol copolymer 30-60

Zeolite 0.5-1.5

Clay 0.5-1.5

Silica 0.5-1.5

0.5 to 1.5 portions of crystallized cellulose;

s2, performing vacuum evaporation on the surface of a high-barrier bottom coating on the upper layer of the paper by adopting a direct vacuum evaporation mode to obtain a transparent medium layer, wherein the transparent medium adopts aluminum oxide or zinc sulfide, and the thickness of a coating is 50-100nm;

s3, performing vacuum evaporation on the surface of the high-barrier bottom coating layer at the lower layer of the paper by adopting a direct vacuum evaporation mode to obtain a metal layer, wherein a plating medium adopts metal aluminum or metal copper, and the thickness of the plating layer is 50-100nm;

s4, respectively carrying out double-sided surface coating on the surface of the transparent medium layer and the surface of the metal layer in a roller coating mode, wherein the surface coating layers are respectively traditional printable polyacrylate system varnish on the front side and solvent-resistant vinyl chloride copolymer emulsion on the back side, and the coating amounts are 1-2 g per square meter.

According to the high-barrier packaging paper and the processing technology thereof, the high-barrier coating is pre-coated on the two sides of the paper, on one hand, the paper exhaust holes are filled to seal the paper fibers, so that the barrier property is improved; the double-sided coating seals the paper by a complete coating, thereby playing an excellent role in blocking water vapor and oxygen; on the other hand, the glossiness of the paper is improved, so that the paper has metal or high-glossiness texture after being subjected to vacuum aluminizing or plating media. The metal layer (aluminum/copper) is coated on one side of the paper to play a role in shading and blocking ultraviolet radiation, and meanwhile, the blocking effect of the paper can be further improved. The solvent-resistant vinyl chloride copolymer of the back coating protects the metal layer on the one hand and directly contacts the contents on the other hand, and the coating needs to have a certain effect of resisting corrosion of chemical components and a certain alcohol-resistant effect. The transparent medium layer can isolate the surface coating from the precoating high-barrier coating, so that the barrier property is reduced due to the erosion and undercut of polyacrylate on the precoating high-barrier coating, and meanwhile, the glossiness of the surface can be effectively improved, the printed image and text on the surface is brighter, and the image and text layering effect is better displayed. The top coat layer protects the dielectric layer on the one hand and has excellent printing adaptability on the other hand. The structural design of the upper layer of the invention ensures that the paper has excellent barrier property of the conventional multi-layer aluminum foil film composite material and also has the environmental protection performance of degradable and recyclable papermaking.

Drawings

FIG. 1 is a schematic view of the layer structure of a high barrier packaging paper of the present invention;

in the figure, 1, a back coating, 2, a metal layer, 3, a second high-barrier primer layer, 4, a raw paper layer, 5, a first high-barrier primer layer, 6, a transparent medium layer, 7 and a top coating.

Detailed Description

The following description of the invention provides further details of the invention.

Example 1

The high-barrier packaging paper sequentially comprises a back coating 1, a metal layer 2, a second high-barrier bottom coating 3, a raw paper layer 4, a first high-barrier bottom coating 5, a transparent medium layer 6 and a top coating 7 from bottom to top;

30-60% of polyvinyl alcohol

Polyamide 5-20

Ethylene-vinyl alcohol copolymer 30-60

Zeolite 0.5-1.5

Clay 0.5-1.5

Silica 0.5-1.5

0.5 to 1.5 portions of crystallized cellulose.

The metal adopted by the metal layer is aluminum or copper.

The top coat adopts traditional printable polyacrylate system varnish.

The back coating adopts solvent-resistant vinyl chloride copolymer emulsion.

Example two

A processing technology of high-barrier packaging paper comprises the following steps:

s1, double-sided precoating is carried out on the front and back surfaces of paper in a double-sided curtain coating mode, the coating amount of the double-sided precoating is 10 g/square meter, and a water-based high-barrier coating is adopted as a high-barrier base coat formed by coating, and comprises the following raw materials in parts by mass:

polyvinyl alcohol 30

Polyamide 5

Ethylene-vinyl alcohol copolymer 30

Zeolite 0.5

Clay 0.5

Silica 0.5

0.5 of crystallized cellulose;

s2, performing vacuum evaporation on the surface of a high-barrier bottom coating on the upper layer of the paper by adopting a direct vacuum evaporation mode to obtain a transparent medium layer, wherein the transparent medium adopts aluminum oxide or zinc sulfide, and the thickness of a coating is 50nm;

s3, performing vacuum evaporation on the surface of the high-barrier bottom coating layer at the lower layer of the paper by adopting a direct vacuum evaporation mode to obtain a metal layer, wherein a plating medium adopts metal aluminum or metal copper, and the thickness of the plating layer is 50nm;

s4, respectively carrying out double-sided surface coating on the surface of the transparent medium layer and the surface of the metal layer in a roller coating mode, wherein the surface coating layers are respectively traditional printable polyacrylate system varnish on the front side and solvent-resistant vinyl chloride copolymer emulsion on the back side.

Example III

s1, double-sided precoating is carried out on the front and back surfaces of paper in a double-sided curtain coating mode, the coating amount of the double-sided precoating is 15 g/square meter, and a water-based high-barrier coating is adopted as a high-barrier base coat formed by coating, and comprises the following raw materials in parts by mass:

polyvinyl alcohol 60

Polyamide 20

Ethylene-vinyl alcohol copolymer 60

Zeolite 1.5

Clay 1.5

Silica 1.5

1.5 parts of crystallized cellulose;

s2, performing vacuum evaporation on the surface of a high-barrier bottom coating on the upper layer of the paper by adopting a direct vacuum evaporation mode to obtain a transparent medium layer, wherein the transparent medium adopts aluminum oxide or zinc sulfide, and the thickness of a coating is 100nm;

s3, performing vacuum evaporation on the surface of the high-barrier bottom coating layer at the lower layer of the paper by adopting a direct vacuum evaporation mode to obtain a metal layer, wherein a plating medium adopts metal aluminum or metal copper, and the thickness of the plating layer is 100nm;

Example IV

s1, double-sided precoating is carried out on the front and back surfaces of paper in a double-sided curtain coating mode, the coating amount of the double-sided precoating is 12 g/square meter, and a water-based high-barrier coating is adopted as a high-barrier base coat formed by coating, and comprises the following raw materials in parts by mass:

polyvinyl alcohol 45

Polyamide 23

Ethylene-vinyl alcohol copolymer 46

Zeolite 1

Clay 1

Silica 1

Crystallizing cellulose 1;

s2, performing vacuum evaporation on the surface of a high-barrier bottom coating on the upper layer of the paper by adopting a direct vacuum evaporation mode to obtain a transparent medium layer, wherein the transparent medium adopts aluminum oxide or zinc sulfide, and the thickness of a coating is 80nm;

s3, performing vacuum evaporation on the surface of the high-barrier bottom coating layer at the lower layer of the paper by adopting a direct vacuum evaporation mode to obtain a metal layer, wherein a plating medium adopts metal aluminum or metal copper, and the thickness of the plating layer is 70nm;

The aqueous high barrier coating formulation of the above examples of the present application was determined by the following experimental analysis procedure:

1. determination of aqueous high barrier coating resin formulation

The barrier performance of the invention is mainly realized by a coating technology, and the coating has application performance besides meeting the barrier performance, such as good leveling, wetting and aluminum layer adhesion. The primary coating is the first procedure of the base paper treatment, and has the main functions of filling the pores on the surface of the base paper and improving the surface smoothness of the base paper. Therefore, the application performance of the primer mainly has good wettability to the surface of the base paper, good self-leveling performance in a high-speed coating state and good interlayer adhesive force with an aluminum layer. In addition, the bottom coating is used as an intermediate layer of the high-barrier aluminized paper structure, and can be used for improving the barrier performance in a synergistic effect with other coatings.

According to the barrier property, leveling property, wetting property and adhesive force of an aluminum layer, four resin raw materials of PVDC, PVA, PA, EVOH are selected for experiments, and the experimental conditions are as follows: the resin system accounts for 50% of the total formulation, the film is coated on the base paper with 80 g/square meter, the coating amount is 3.0 g/square meter, and the experimental results are shown in the following table:

table 1 experimental results of aqueous high barrier coating resin formulation

Project	Unit (B)	DTS-01	DTS-02	DTS-03	DTS-04	DTS-05	DTS-06
								PVDC	%	50	/	30	/	/	/
PVA	%	50	50	20	50	/	40
								PA	%	/	20	50	/	50	10
EVOH	%	/	30	/	50	50	50
								Air permeability	μm/Pa·s	3.5E-08	4.0E-08	7.5E-08	3.0E-08	5.5E-07	2.0E-08
Moisture permeability	g/m ² ·d	8.6	14.5	10.3	2.4	7.8	2.1
								Ethanol resistance	Secondary times	20	30	＞50	＞50	＞50	＞50
Water resistance	Secondary times	30	20	30	＞50	＞50	＞50
								Adhesion of aluminum layer	%	90	95	95	90	90	100

From the experimental results in table 1, it can be seen that:

when PVDC is used as a main system, the barrier property is good, but the adhesive force of an aluminum layer is slightly poor, and the result is shown as DTS-01; when polyvinyl alcohol PVA is used as a main system, the water resistance and the moisture permeability deviate, and the results are shown as DTS-01 and DTS-02; when polyamide PA is used as a main system, the barrier property is moderate, the adhesive force of an aluminum layer is good, and the results are shown as DTS-03 and DTS-05; when the vinyl alcohol copolymer EVOH is used as a main system, the barrier property is moderate, the adhesive force of the aluminum layer is greatly related to the compound, and the results are shown in DTS-04 and DTS-05.

2. Determination of aqueous high barrier coating filler formulation

The experimental conditions for the filler formulation of the water-based barrier coating for the basecoat were DTS-06: the resin system, 50% of the amount, 3.0% of the amount of filler, is coated on 57 g/square meter base paper to form a film, the coating amount is 10.0 g/square meter, and the experimental results are shown in the following table:

table 2 experimental results of aqueous high barrier coating filler formulation

Project

Unit (B)

DTT-01

DTT-02

DTT-03

DTT-04

DTT-05

Silica dioxide

%

1.5

/

Zeolite

%

/

1.5

/

1.5

Clay

%

/

1.5

/

Crystallized cellulose

%

1.5

/

1.5

Air permeability

μm/Pa·s

2.5E-08

3.0E-08

2.6E-08

2.0E-08

Moisture permeability

g/m ² ·d

1.8

2.3

2.2

1.65

1.1

Water resistance

Secondary times

≥50

Ethanol resistance

≥50

Temperature resistance

℃

150

160

145

140

From the experimental results in table 2, it can be seen that:

different fillers are added into the same resin system, so that the barrier property and the application property can be improved to a certain extent. The silica filler increases the heat resistance while improving the barrier property; the zeolite can improve the barrier property of the coating to liquid or gas; the clay can effectively improve the blocking effect of the coating on moisture; the composite application of the crystallized cellulose, silicon dioxide, clay and zeolite can greatly improve the barrier property and respectively improve the temperature resistance and the water resistance.

In summary, according to the performance requirements of the coating, the formula of the primer is selected to give priority to the adhesion fastness of the aluminum layer, and other performances are as follows: the water resistance and barrier properties can be offset by fillers or interlayer synergism. And (3) final determination: the resin system is preferably: polyvinyl alcohol PVA and vinyl alcohol copolymer EVOH are used as main systems, and polyamide PA is used as an auxiliary system; the filler system is preferably crystallized cellulose as a main material, and is supplemented with silicon dioxide, clay and zeolite, and the dosage of the filler system is 2.0-5.0% of the total system of the formula.

The scope of the present invention is not limited to the above embodiments, but is intended to be within the scope of the appended claims, along with any modifications, equivalents, or improvements thereto, which are within the spirit and scope of the invention. The technical proposal is not described in detail and is known in the prior art. All the preparation methods of the multicolor anti-counterfeiting paper which are the same as or equal to the technical scheme of the invention belong to the protection scope of the invention.

Claims

1. The high-barrier packaging paper is characterized by sequentially comprising a back coating, a metal layer, a high-barrier bottom coating II, a raw paper layer, a high-barrier bottom coating I, a transparent medium layer and a top coating from bottom to top;

30-60% of polyvinyl alcohol

Polyamide 5-20

Ethylene-vinyl alcohol copolymer 30-60

Zeolite 0.5-1.5

Clay 0.5-1.5

Silica 0.5-1.5

0.5 to 1.5 portions of crystallized cellulose;

the processing technology of the high-barrier packaging paper comprises the following steps of:

s1, carrying out double-sided precoating on the front and back surfaces of paper, wherein the coating weight is 10-15 g/square meter, and a high-barrier primer coating formed by coating adopts a water-based high-barrier coating and comprises the following raw materials in parts by mass:

30-60% of polyvinyl alcohol

Polyamide 5-20

Ethylene-vinyl alcohol copolymer 30-60

Zeolite 0.5-1.5

Clay 0.5-1.5

Silica 0.5-1.5

0.5 to 1.5 portions of crystallized cellulose;

s2, carrying out vacuum evaporation on the surface of a high-barrier bottom coating on the upper layer of the paper to obtain a transparent medium layer, wherein the thickness of a coating of the transparent medium layer is 50-100nm, and the transparent medium adopts aluminum oxide or zinc sulfide;

s3, carrying out vacuum evaporation on the surface of a high-barrier bottom coating layer on the lower layer of the paper to obtain a metal layer, wherein the plating thickness of the metal layer is 50-100nm, and a plating medium adopts metal aluminum or metal copper;

s4, carrying out double-sided surface coating on the surface of the transparent medium layer and the surface of the metal layer, wherein the coating weight is 1-2 g per square meter, and the surface coating is respectively a traditional printable polyacrylate system varnish on the front side and a solvent-resistant vinyl chloride copolymer emulsion on the back side.

2. A high barrier packaging paper as claimed in claim 1, wherein,