Manufacturing method of vacuum aluminum-plated base paper

Abstract

The invention discloses a manufacturing method of vacuum aluminum-plated base paper, which comprises the following steps: coating a smooth surface of the base paper with a finish paint mixed with a pigment with wide particle size distribution, alkali-sensitive resin, a sizing material, an adhesive, a cross-linking coupling agent, a sizing agent and other auxiliaries by using a coating machine to obtain a compact mixed three-dimensional coating structure with strong cohesiveness; the alkali permeation speed and alkali resistance of the vacuum aluminized body paper are improved, the requirement of a beer label washing bottle label removing procedure is met, meanwhile, by improving the sizing degree of a surface coating and matching with a compact coating structure, excessive permeation during follow-up coating of aluminized primer can be effectively blocked, the aluminized effect is improved, large-particle-size filler is added into the back coating, and the service life of the back coating is prolonged. Through cooperation with the sizing agent, the water repellent agent and other assistants, the structural mechanism that a certain water repellent effect is achieved, and the bottle pasting glue can be adsorbed through the capillary absorption effect of the micro concave holes is formed, and the adhesion performance of the bottle pasting glue is improved.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a label material, in particular to a method for manufacturing a paper-based material for vacuum aluminum plating. Background Art

[0002] Vacuum-coated aluminum paper is a composite material in which an extremely thin layer of aluminum is deposited onto the surface of paper through a vacuum evaporation process. The production process takes place in a high vacuum environment, where the aluminum metal is heated and vaporized, then evenly adhered to the paper surface, forming a nanoscale aluminum film. This technology replaces traditional rolled aluminum foil, combining the flexibility of paper with the functionality of metal. The vacuum-coated paper surface exhibits a mirror-like metallic texture, significantly elevating the product's quality. It is widely used in food packaging (such as candy and chocolate packaging), cosmetics packaging (such as skin care products and perfume boxes), cigarette packaging (as lining paper for cigarette boxes), and product labels (such as wine bottle neck labels, luxury goods hang tags, greeting cards, and book covers).

[0003] The finished performance of vacuum-aluminized paper depends primarily on the properties of the base paper. For label applications such as food packaging, cosmetics, luxury goods, and greeting cards, key performance indicators include strength, surface properties, optical properties, printability, water absorption, wet deformation resistance, and flatness. However, for wine bottle neck labels, in addition to the aforementioned properties, excellent wet strength, alkali permeability, alkali resistance, water curling, and weather resistance are also essential. Therefore, vacuum-aluminized paper for wine labels places even higher demands on the base paper.

[0004] Vacuum-aluminized paper for wine labels must exhibit excellent water-curling properties and bottle-applying adhesive adhesion. This means that during the labeling process, the back of the paper is coated with water-based bottle-applying adhesive. This requires excellent adhesive adhesion, no curling or warping, when applying small, single labels to bottles, ensuring a smooth labeling process. Vacuum-aluminized paper for wine labels must also meet the operational requirements of bottle recycling and label removal. This means that labels must be quickly and completely removed during bottle washing. This requires both the fiber and coating layers of the vacuum-aluminized paper to be alkali-resistant, and the coating layer to be highly alkali-resistant, ensuring quick, complete label removal during bottle washing.

[0005] Currently, vacuum-aluminized paper for beer labels is typically produced by off-machine coating and then over-pressing. Minfeng Specialty Paper Co., Ltd. has applied for an invention patent (patent application number: 200810143031.7) for a "Method for Producing Water-Resistant Vacuum Aluminized Paper." This patented method can be used to produce vacuum-aluminized paper for beer labels. The patent discloses that by coating the paper once or twice on one side, vacuum-aluminized paper with excellent flatness and high brightness can be produced. This paper also possesses sufficient wet strength and alkali resistance to ensure that the label remains intact when wet and maintains integrity during bottle washing. The patent claims to improve the fiber's alkali resistance by adding a wet strength agent during papermaking. However, it does not describe how the coating improves alkali permeability and alkali resistance. This could lead to the coating soaking off too quickly during bottle washing, contaminating the washing liquid. Furthermore, there is no mention of how to improve the back-side adhesion of the label to the bottle.

[0006] Minfeng Specialty Paper Co., Ltd. has applied for a utility model patent for "Type B Vacuum Aluminized Paper" (patent application number: 201520495897.X), disclosing the structure of vacuum aluminized paper for beer labels. The patent provides a Type B vacuum aluminized paper with excellent water-resistance and moisture sensitivity, addressing the moisture sensitivity and rapid curling of single-sided coated vacuum aluminized paper. However, the patent does not address the coating's alkali resistance and alkali permeability, nor does it address improving the back-side adhesion of labels to bottles.

[0007] Minfeng Special Paper Co., Ltd. has applied for an invention patent for "A back coating for highly water-resistant vacuum aluminized paper" (patent application number: 201910688957.2), which discloses a back coating for highly water-resistant vacuum aluminized paper. This patent mainly solves the problem of low solid content of glue when labeling special-shaped labels, preventing more water from being absorbed by the label and causing wrinkles in the label. The problem is solved by applying a layer of coating of uniform thickness on the back of the paper to seal the fiber layer, which acts as a water barrier and prevents more water from penetrating. This patent can prevent low-concentration bottle glue by sealing the back, but does not propose how to improve the adhesion performance of the bottle on the back. At the same time, the closed back coating will also affect the penetration rate of alkali when washing the bottle, resulting in problems such as slow label removal, and there is no mention of how to solve the problem of alkali resistance and alkali penetration rate of the front coating.

[0008] Xianhe Co., Ltd. has applied for an invention patent (patent application number: 202311687218.4) for a "Method for Producing High-Strength Aluminized Paper." The patent describes a method for producing high-strength aluminized paper that improves paper strength without reducing surface roughness. The patent primarily addresses improving paper strength and surface smoothness, but does not address the coating's alkali resistance and alkali permeation rate, nor does it address improving the back-side adhesion of bottles.

[0009] Huainan Tongyu Plastic Weaving Co., Ltd. has applied for an invention patent for "A method for producing base paper for vacuum aluminizing" (patent application number: 201810037744.9), and announced a method for producing vacuum aluminizing base paper with good surface flatness and glossiness, suitable for packaging and printing. This method improves the flatness and glossiness of the paper, improves the smoothness of the aluminum film after aluminizing, and improves the performance of aluminized paper, making it suitable for use in the field of packaging and printing. It can be seen that this patent mainly solves the problems of surface flatness and glossiness, thereby improving the aluminizing effect. It does not mention how to solve the problems of alkali resistance and alkali permeability of the coating, nor does it mention how to improve the adhesion performance of the bottle on the back.

[0010] Yueyang Forest & Paper Co., Ltd. has applied for an invention patent for a "vacuum aluminum-coated base paper and its manufacturing method" (patent application number: 201410283303.9). The patented method claims that the coated paper "achieves better coating coverage, surface roughness, water resistance, and glossiness than traditional lightweight coated paper, thereby meeting the requirements of vacuum aluminum coating." The patent does not address the issues of coating alkali resistance and alkali permeability. Furthermore, the wet strength agent is removed during base papermaking, significantly reducing the alkali resistance of the vacuum aluminum-coated base paper. This makes labels easily break during alkali cleaning, hindering bottle washing operations. The patent also fails to address how to improve the adhesion of labels to the back of bottles.

[0011] Therefore, it is necessary to develop a vacuum aluminized base paper. The label made of this paper should have good bottle adhesive adhesion performance on the back. At the same time, when washing bottles and removing labels, the label should also have good alkali resistance and alkali permeability. That is, the fiber layer and coating of the paper both have good alkali resistance, and the front and back coatings have a fast alkali permeability, which meets the application requirements of vacuum aluminized base paper for beer labels. Summary of the Invention

[0012] The present invention provides a method for manufacturing vacuum aluminized base paper. In this method, a topcoat is applied to the smooth front surface of the base paper to form a dense topcoat structure. The topcoat structure is alkali-permeable and water-impermeable, while also having good alkali resistance. A backcoat is applied to the back surface of the base paper to form a coating structure with micro-concave pores. This allows the resulting label to have good bottle-sticking performance and bottle adhesive adhesion. Furthermore, the backcoat structure also has good hydrophobicity, alkali resistance, and alkali permeability, thereby resolving current application problems such as poor bottle-sticking performance, poor alkali permeability, and poor alkali resistance of wine labels during bottle washing and label removal.

[0013] In order to achieve the above object, the technical solutions adopted by the present invention are as follows:

[0014] (1) The topcoat is applied to the smooth surface of the base paper using a coating machine to obtain a dense topcoat structure. In the topcoat, pigments of different particle shapes and sizes are combined to form a wide particle size distribution. Alkali-sensitive resins and sizing agents, adhesives, and cross-linking coupling agents are added to form a dense mixed three-dimensional coating structure with the pigments of wide particle size distribution, which significantly improves the water barrier performance. The alkali-sensitive resins and sizing agents mixed and dispersed in the dense coating are destroyed by alkali liquid, forming a channel for the alkali liquid to penetrate the coating. The cross-linking coupling agent improves the bonding strength between the pigment particles and the adhesive, which can effectively resist the damage of water and alkali liquid. When soaked in bottle washing alkali liquid, the alkali penetration rate is increased, while the structure and bonding strength formed by the pigment, adhesive, and cross-linking coupling agent are retained to ensure good alkali resistance of the coating. By controlling the good water retention and shear viscosity properties of the topcoat, the excessive penetration of the continuous phase in the wet coating on the paper surface during coating is reduced, and the dense structure of the coating can be effectively maintained. By adding gloss enhancing agents, plasticizers and lubricants, the calendering finishing effect of the coating can be improved. By adding sizing agents, the sizing degree of the coating can be increased. Combined with a dense coating structure, it can effectively block excessive penetration during the subsequent coating of the aluminum plating primer and improve the aluminum plating effect.

[0015] A back coating is applied to the rough surface of the base paper using a coating machine, creating an open back coating structure. By incorporating an appropriate amount of large-particle fillers and adhesives into the back coating, an open coating structure with microporous pores forms on the fiber surface. This facilitates capillary action, absorbing the bottle adhesive and improving adhesion between the adhesive and the coating. The addition of a cross-linking coupling agent enhances the bond between the large-particle fillers, adhesive, and fiber, thereby improving the back coating's alkali resistance. The addition of a sizing agent, which coats the fiber surface, reduces the back fiber's sensitivity to water and moisture, reduces curling during bottle adhesive application, and improves smoothing performance under varying humidity conditions. The back coating does not seal the fiber surface, preserving micropores between the fibers. These, combined with the large-particle microporous structure on the surface, create a capillary action, enhancing the adhesion of the bottle adhesive and preventing issues such as warping, slippage, and loose adhesion during bottle application. At the same time, the relatively open back coating helps to increase the alkali permeation speed and shorten the label removal time; after the front and back sides of the paper are coated, the front side is attached to the steel roller and calendered and wound up to obtain the vacuum aluminum-plated base paper for wine labels of this patent.

[0016] (2) To prepare a topcoat, add 0.1 to 10 parts of an alkali-sensitive resin and a sizing agent to 100 parts of a pigment, 0.1 to 5 parts of a cross-linking coupling agent, and 0.1 to 5 parts of a sizing agent. The viscosity of the prepared coating is not greater than 2500 cp.

[0017] (3) The alkali-sensitive resins and sizing materials added to the topcoat include, but are not limited to, modified phenolic resins, modified epoxy resins, modified natural rubber, casein, soy protein, fish glue, bone glue, modified starch, cellulose and its derivatives, modified rosin glue and its derivatives, and a combination of one or more thereof.

[0018] (4) The cross-linking coupling agent added to the topcoat includes but is not limited to one or more combinations of glyoxal, ammonium zirconium carbonate, potassium zirconium carbonate, polyamide polyurea resin, melamine, silane coupling agent, borate, titanate, aluminate coupling agent, aziridine cross-linking agent, etc.

[0019] (5) The sizing agent added to the topcoat includes but is not limited to styrene maleic anhydride copolymers, paraffin waxes, acrylates, modified polyurethanes, styrene acrylic copolymers, or a combination thereof.

[0020] (6) The pigments used include but are not limited to ground heavy calcium, china clay, calcined clay, precipitated calcium carbonate, titanium dioxide, talc, calcium sulfate, aluminum hydroxide, silicon dioxide, etc., or a combination thereof.

[0021] (7) The topcoat is completed by one or two coats. The coating method includes but is not limited to a doctor blade coating method, a pneumatic coating method, a doctor bar coating method, a pre-metered film transfer coating method, an anilox roller coating method, a curtain coating method, or a combination of two coating methods. The total coating amount is 1 to 25 g / m 2 .

[0022] (8) The proportion of large-particle filler used in the back coating is 100 parts, the proportion of adhesive is 10 to 50 parts, the proportion of cross-linking coupling agent is 0.1 to 20 parts, and the proportion of sizing agent is 0.1 to 30 parts. The back coating is prepared and the coating viscosity is not greater than 1500cp.

[0023] (9) The median particle size of the large particle filler in the back coating is ≥2μm, and the types include but are not limited to one or more combinations of inorganic pigments, resin particles, natural rubber particles, etc.; the cross-linking coupling agent is one or more combinations used in the top coating; the sizing agent is one or more combinations used in the top coating.

[0024] (10) The back coating adopts a one-step coating method, and the coating method includes but is not limited to a blade coating method, a pneumatic coating method, a scraper coating method, a pre-measured film transfer coating method, an anilox roller coating method, and a LAS coating method. The coating amount is 0.5 to 10 g / m 2 .

[0025] This patented technology utilizes a coating machine to apply a topcoat containing pigments with a wide particle size distribution, alkali-sensitive resins, sizing agents, adhesives, cross-linking coupling agents, and other additives to the smooth surface of base paper. This creates a dense, three-dimensional, mixed coating structure that is alkali-permeable but water-impermeable. This increases the rate of high-alkali penetration while retaining the structure and bond strength formed by the pigments, adhesives, and cross-linking coupling agents, ensuring excellent alkali resistance. The topcoat's water-blocking properties effectively prevent excessive penetration during subsequent application of aluminized primer, improving the aluminizing effect. A coating machine is used to apply a back coating containing additives such as large-particle fillers, adhesives, cross-linking coupling agents, and sizing agents to the rough surface of the base paper. This creates a structural mechanism that not only has a certain hydrophobic effect but also can adsorb bottle adhesive through capillary absorption of micro-concave pores, improving the adhesion performance of the bottle adhesive. At the same time, the cross-linking coupling agent improves the bond between the large-particle fillers, adhesives, and fibers, thereby improving the alkali resistance of the back coating. The open back coating increases the penetration rate of alkali solution. Therefore, the vacuum aluminum-plated base paper produced by the manufacturing method of vacuum aluminum-plated base paper disclosed in the present invention has good alkali resistance and alkali permeability. At the same time, the back structure provides a good labeling effect, avoiding problems such as warping, label slippage, and weak adhesion when labeling bottles. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is an electron microscope image of the back side of the vacuum aluminum-plated base paper in embodiment 1 of this patent.

[0027] Figure 2 This is an electron microscope image of the back of the vacuum aluminized base paper for comparison. DETAILED DESCRIPTION

[0028] Implementation Method 1

[0029] The topcoat was prepared using a mixing tank. The topcoat contained 70 parts of china clay, 30 parts of light calcium carbonate, 2 parts of silane coupling agent, 3 parts of soy protein, 4 parts of modified starch, 0.8 parts of acrylate sizing agent, 0.5 parts of CMC thickener, 12 parts of styrene-butadiene latex, 0.8 parts of glycerin, and 1 part of calcium stearate lubricant. The viscosity of the prepared coating was 1500cp. The coating was applied by a blade with a coating amount of 20g / m 2 The coating speed is 350m / min, and the moisture content of the machine is controlled at 3.0-4.0%. The back coating is prepared using a batching tank. 100 parts of large-particle filler are added to the back coating. The large-particle filler is calcium carbonate with a median particle size of 11μm. The proportion of styrene-acrylic emulsion adhesive is 25 parts, 5 parts of silane coupling agent, and 10 parts of modified polyurethane sizing agent are added. The viscosity of the prepared coating is 300cp. Air knife coating is used, and the coating amount is 7g / m 2 The coating speed is 350m / min, and the moisture content off the machine is controlled at 4.5-5.5%. After the front and back sides are coated, the front side is attached to the steel roller and calendered and wound up to obtain the patented vacuum aluminized base paper for wine labels.

[0030] Implementation Method 2

[0031] The topcoat was prepared using a mixing tank. The topcoat contained 80 parts of china clay, 20 parts of ground calcium carbonate, 1.5 parts of ammonium zirconium carbonate additive, 2 parts of glyoxal additive, 5 parts of casein, 2 parts of modified starch, 1.5 parts of modified rosin glue, 1.5 parts of modified rosin glue, 0.5 parts of styrene-maleic anhydride copolymer sizing agent, 0.8 parts of CMC thickener, 11 parts of styrene-butadiene latex, 0.6 parts of glycerol, and 1.5 parts of calcium stearate lubricant. The prepared coating had a viscosity of 900cp. The coating was applied twice using a scraper and a scraper, with a coating amount of 23g / m 2 The coating speed is 300m / min, and the moisture content of the machine is controlled at 4.0-5.0%. The back coating is prepared using a batching tank. 100 parts of large-particle filler are added to the back coating. The large-particle filler is calcined clay with a median particle size of 5μm. The proportion of styrene-butadiene latex is 45 parts. 12 parts of polyamide polyurea resin are added. 7 parts of modified acrylic ester sizing agent are added. The viscosity of the prepared coating is 200cp. LAS coating method is used, and the coating amount is 2g / m 2The coating speed is 300m / min, and the moisture content off the machine is controlled at 4.5-5.5%. After the front and back sides are coated, the front side is pasted on a steel roller, calendered and finished, and then rolled up to obtain the patented vacuum aluminized base paper for wine labels.

[0032] Implementation 3

[0033] The topcoat was prepared using a mixing tank. The topcoat contained 60 parts china clay and 40 parts talc. The topcoat also contained 3 parts aluminate coupling agent, 0.8 parts melamine additive, 2 parts bone glue, 3 parts modified starch, 0.5 parts modified polyurethane sizing agent, 0.5 parts CMC thickener, 13 parts styrene-butadiene latex, and 1.5 parts calcium stearate lubricant. The resulting coating had a viscosity of 1200 cp. The backcoat was prepared using a mixing tank. The backcoat contained 100 parts of large-particle filler (silica with a median particle size of 8 μm), 15 parts of ethylene vinyl acetate emulsion adhesive, 3 parts of silane coupling agent, and 6 parts of modified maleic anhydride copolymer sizing agent. The resulting coating had a viscosity of 800 cp. The prepared top coating and back coating are coated by pre-measured film transfer coating, that is, the top coating is applied on the front side and the back coating is applied on the back side. The front and back sides are coated at the same time. The coating amount on the front side is 13g / m 2 , the back coating amount is 7g / m 2 The coating speed is 350m / min, and the moisture content off the machine is controlled at 4.5-5.5%. After the front and back sides are coated, the front side is calendered and finished by a soft calender on a steel roller, and then rolled up to obtain the vacuum aluminized base paper for wine labels of this patent.

[0034] The three samples of the embodiment and the comparative samples of the existing products on the market were tested, as shown in the following table:

[0035]

[0036] The vacuum aluminum-plated base paper for wine labels prepared by the method of the present invention has a tested alkali permeation speed of less than 60 seconds, which is more than 30 seconds faster than the comparative sample of existing products on the market; the vacuum aluminum-plated base paper is intact in the alkali resistance test, the coating does not fall off, and the tested alkali solution does not become turbid, which is better than the alkali resistance of the comparative sample of existing products on the market, and the comparative sample has the problem of partial shedding of the coating; the Cobb water absorption of the front and back sides is less than 20g / m 2 , has good water-blocking performance; and the initial curling time of the back side of the vacuum aluminized base paper for wine labels prepared by the present invention is better than that of the control sample; the back side structure improves the adhesion of the bottle glue, has a good labeling effect, and avoids the problems of warping, slipping, and weak adhesion when labeling the bottle.

Claims

1. A method for manufacturing vacuum aluminized base paper, characterized in that: A topcoat is applied to the front side of the base paper, and a backcoat is applied to the back side of the base paper; the topcoat includes an alkali-sensitive resin and a sizing agent, and the backcoat includes a large-particle filler; after drying, the topcoat is dense, smooth, alkali-permeable and water-impermeable, while the backcoat is open, forming a coating structure with micro-concave pores.

2. The method for manufacturing vacuum aluminized base paper according to claim 1, wherein: In the topcoat, the proportion of alkali-sensitive resin and sizing agent added to 100 parts of pigment is 0.1 to 10 parts, the proportion of cross-linking coupling agent added is 0.1 to 5 parts, and the proportion of sizing agent added is 0.1 to 5 parts. The viscosity of the prepared coating is not greater than 2500cp.

3. The method for manufacturing vacuum aluminized base paper according to claim 1, wherein: The alkali-sensitive resin and sizing agent added to the topcoat include, but are not limited to, one or more combinations of modified phenolic resin, modified epoxy resin, modified natural rubber, casein, soy protein, fish glue, bone glue, modified starch, cellulose and its derivatives, modified rosin glue and its derivatives.

4. The method for manufacturing vacuum aluminized base paper according to claim 1, wherein: The cross-linking coupling agent formulated into the topcoat includes, but is not limited to, one or more combinations of glyoxal, ammonium zirconium carbonate, potassium zirconium carbonate, polyamide polyurea resins, melamine, silane coupling agents, borate, titanate, aluminate coupling agents, aziridine cross-linking agents, etc.

5. The method for manufacturing vacuum aluminized base paper according to claim 1, wherein: The sizing agent added to the topcoat includes, but is not limited to, one or more combinations of styrene maleic anhydride copolymers, paraffin waxes, acrylates, modified polyurethanes, styrene acrylic copolymers, and the like.

6. The method for manufacturing vacuum aluminized base paper according to claim 1, wherein: The pigments used in the topcoat include, but are not limited to, ground heavy calcium, china clay, calcined clay, precipitated calcium carbonate, titanium dioxide, talc, calcium sulfate, aluminum hydroxide, silicon dioxide, and one or more combinations thereof.

7. The method for manufacturing vacuum aluminum-plated base paper according to claim 1, wherein: The top coating is completed in one or two coats, or simultaneously with the back coating. The coating methods include but are not limited to blade coating, pneumatic coating, bar coating, pre-metered film transfer coating, anilox roller coating, curtain coating, etc., or a combination of two coating methods. The total coating weight is 1-25g / m 2 .

8. The method for manufacturing vacuum aluminum-plated base paper according to claim 1, wherein: The proportion of large-particle filler used in the back coating is 100 parts, the proportion of adhesive is 10-50 parts, the proportion of cross-linking coupling agent is 0.1-20 parts, and the proportion of sizing agent is 0.1-30 parts. The back coating has a viscosity of no more than 1500cp.

9. The method for manufacturing vacuum aluminum-plated base paper according to claim 1, wherein: The median particle size of the large particle filler in the back coating is ≥2μm, and the types include but are not limited to one or more combinations of inorganic pigments, resin particles, natural rubber particles, etc.; the cross-linking coupling agents include but are not limited to one or more combinations of glyoxal, ammonium zirconium carbonate, potassium zirconium carbonate, polyamide polyurea resins, melamine, silane coupling agents, borate, titanate, aluminate coupling agents, aziridine cross-linking agents, etc.; the sizing agents include but are not limited to one or more combinations of styrene maleic anhydride copolymers, paraffins, acrylates, modified polyurethanes, styrene acrylic copolymers, etc.

10. The method for manufacturing vacuum aluminum-plated base paper according to claim 1, wherein: The back coating is completed in one coat or simultaneously with the top coating. The coating methods include but are not limited to blade coating, pneumatic coating, bar coating, pre-metered film transfer coating, anilox roller coating, and LAS coating. The coating amount is 0.5-10g / m 2 .

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