Explosion-proof colored metal brushed cigarette packaging paper and preparation method thereof

Abstract

The present invention relates to the technical field of cigarette packaging paper, and in particular to an explosion-proof colored metal brushed cigarette packaging paper and a preparation method thereof. This cigarette packaging paper comprises a base paper layer, a buffer layer and a metal layer arranged in sequence; the buffer layer comprises a core-shell structure with a plastic material as a shell and a negative expansion material as a core, and the negative expansion material is selected from a material with negative expansion characteristics in the range of 0°C-100°C. Under heating conditions, the volume of the negative expansion material core shrinks due to heating, so that a gap is generated between the plastic material shell and the core. On the one hand, the gap accommodates the difference caused by thermal expansion through deformation and compression, and on the other hand, it can reduce the contact area to reduce heat conduction, thereby alleviating the impact of thermal expansion; thereby reducing the stress concentration problem under heating conditions, and preventing peeling between layers, or the problem of bulging of a layer with a large expansion coefficient or cracking of a layer with a small expansion coefficient.

Description

Technical Field

[0001] The invention relates to the technical field of cigarette packaging paper, in particular to explosion-proof colored metal brushed cigarette packaging paper and a preparation method thereof. Background Art

[0002] Cigarette packaging is a crucial component of cigarette production and the final step in the entire production process. Throughout the entire process of cigarette production, distribution, and consumption, the quality of packaging materials plays a crucial role in maintaining product quality, promoting sales, and guiding consumption. Compared to other commodities, cigarette packaging materials have specific requirements, such as being odorless, non-toxic, and possessing moisture resistance and insulation properties.

[0003] Paper-plastic-aluminum composite paper is a laminated paper made by gluing paper, plastic film, and aluminum foil (or aluminized film). This composite paper combines the high barrier properties of aluminum foil, the flexibility of plastic film, and the folding and impact resistance of paper, making it a high-performance packaging material widely used for packaging a variety of goods. In the cigarette industry, paper-plastic-aluminum composite paper can be used to wrap cigarettes in cigarette boxes, maintaining the necessary storage environment for the cigarettes, retaining their moisture, and slowing the loss of their flavor components. However, this type of paper-plastic-aluminum composite paper often suffers from color bleed, which not only affects the aesthetics but also the quality of printed products. Severe bleed can lead to the rejection of printed products.

[0004] Prior art solutions to color popping often focus on improving adhesion. For example, patent publication number CN210501773U discloses a color popping-proof composite paper comprising, from bottom to top, a PP film layer, a first adhesive layer, a base paper layer, a second adhesive layer, a composite film layer, and a varnish layer. The composite film layer is composed of five mutually bonded layers: an aluminum layer, a laser information layer, a coating layer, a transparent waterproof layer, and a double-sided corona-treated plastic film layer. A primer layer containing 15-20 wt% of a silane coupling agent is applied to the lower surface of the aluminum layer and the upper surface of the double-sided corona-treated plastic film layer. This primer layer improves the surface wettability and adhesion of the aluminum layer and the double-sided corona-treated plastic film layer, thereby enhancing the bonding strength between the aluminum layer and the second adhesive layer, and between the double-sided corona-treated plastic film layer and the varnish layer, effectively alleviating the color popping problem in the composite paper.

[0005] However, in actual applications, it was found that its adhesion needs to be improved. At the same time, due to the different thermal expansion coefficients of each layer, when heated, there will still be problems such as bulging of a layer with a large expansion coefficient or cracking of a layer with a small expansion coefficient. Summary of the Invention

[0006] The present invention aims to solve the above problems and provides an explosion-proof colored metal brushed cigarette packaging paper and a preparation method thereof.

[0007] The technical solution to the problem solved by the present invention is to first provide an explosion-proof colored metal brushed cigarette packaging paper, which includes a base paper layer, a buffer layer and a metal layer arranged in sequence; the buffer layer includes a core-shell structure with a plastic material as a shell and a negative expansion material as a core, and the negative expansion material is selected from a material with negative expansion characteristics in the range of 0°C-100°C.

[0008] Among them, plastic material refers to a material that can undergo plastic deformation without breaking when subjected to a certain tensile force. Suitable plastic materials include one or more of polyvinyl alcohol, polyester, polyurethane, polyamide, polylactic acid, and polypropylene.

[0009] Negative expansion material refers to a material whose overall size or crystal size in one or several directions shrinks as the temperature rises within a certain temperature range. In order to adapt to the storage and use environment of cigarette packaging paper, the negative expansion material of this application should be selected from materials with negative expansion characteristics in the range of 0℃-100℃; preferably, materials with negative expansion characteristics in the range of 0℃-60℃. Suitable thermal expansion materials include one or more of PbTiO3, ZrW2O8, and HfW2O8. Among them, PbTiO3 exhibits negative thermal expansion characteristics in the range of room temperature to 490℃, and the thermal expansion coefficient is approximately -5.4×10 - 6 C -1 ;

[0010] ZrW2O8 and HfW2O8 exhibit negative thermal expansion characteristics in the range of 0℃-507℃, with a thermal expansion coefficient of approximately -8.7×10 -6 C -1 .

[0011] In this application, a buffer layer is used to mitigate the thermal expansion difference between the base paper layer and the metal layer. Specifically, under heated conditions, the negative expansion material core shrinks in volume due to heat, creating a gap between the plastic shell and the core. This gap accommodates the difference in thermal expansion through deformation and compression, while also reducing the contact area to reduce heat conduction and mitigate the effects of thermal expansion. This reduces stress concentration under heated conditions and prevents peeling between layers, or bulging of a layer with a high expansion coefficient or cracking of a layer with a low expansion coefficient. Under unheated conditions, the negative expansion material returns to its larger volume, filling the gap within the plastic shell. The resulting core-shell structure fills the gap between the base paper layer and the metal layer, preventing weakening of the overall packaging paper structure and improving the connection strength between the base paper layer and the metal layer.

[0012] To protect the core-shell structure and further mitigate the thermal expansion differential between the base paper layer and the metal layer, the buffer layer preferably includes a foam matrix, with the core-shell structure preferably filling the pores of the foam matrix. The foam matrix supports the core-shell structure, preventing it from being damaged when the wrapping paper is subjected to significant external forces. The pores of the foam matrix also further absorb the thermal expansion differential.

[0013] Preferably, the foam substrate is a metal foam. Like the metal layer, the metal foam itself can expand thermally, but compared to the metal layer, the metal foam has larger spacing and a relatively lower degree of thermal expansion. Thus, the metal foam acts as a medium expansion coefficient material between the base paper layer and the metal layer, further buffering the thermal expansion difference.

[0014] Preferably, the metal used for the metal foam is the same as that used for the metal layer, further adapting to the thermal expansion of the metal layer. To ensure a hot stamping effect, the metal layer is preferably one or more of gold, silver, copper, and aluminum. Considering cost, aluminum is preferred. Therefore, the metal foam can be one or more of gold foam, silver foam, copper foam, and aluminum foam, with aluminum foam being preferred.

[0015] To improve the connection between the buffer layer and the base paper layer and metal layer, and to facilitate the dispersion of the core-shell structure, or the core-shell structure and the foam matrix, the buffer layer preferably further comprises an adhesive. In some embodiments, the choice of adhesive is not limited, and one or more of silicone, acrylic, silicone, and phenolic adhesives may be selected.

[0016] In other embodiments, first, as a preferred embodiment of the present invention, the base paper layer comprises polyethylene terephthalate. Adding polyethylene terephthalate during the papermaking process can significantly improve the tensile strength of the base paper layer, further alleviating bulging or cracking issues caused by thermal expansion mismatches with other layers.

[0017] Secondly, as a preferred embodiment of the present invention, the adhesive comprises an acrylic acid graft copolymer modified polyurethane resin. This acrylic acid graft copolymer modified polyurethane resin is a copolymer of acrylic acid grafted polyurethane obtained by reacting a polyether polyurethane prepolymer with acrylic acid, and is typically AA-g-PU. While the base paper layer comprises polyester, the buffer layer utilizes an acrylic acid graft copolymer modified polyurethane resin. This resin exhibits excellent adhesion to polyethylene terephthalate, facilitates film formation, and does not compromise the toughness of the base paper layer.

[0018] Generally speaking, cracking in a composite wrapping paper layer is not only related to thermal expansion mismatch with other layers, but also to its own flexibility and moisture content. For example, a low moisture content in the base paper layer can lead to drying and brittleness. Therefore, based on the above embodiment, as a preferred embodiment of the present invention, the buffer layer also includes a coating of super-water-dispersible carbon black.

[0019] Polyethylene terephthalate is a known resin with a certain degree of water absorption. As a preferred embodiment of the present invention, the buffer layer also includes coated super-water-dispersible carbon black. Coated super-water-dispersible carbon black, a water-coated carbon black composite, is applied to the base paper layer as part of the buffer layer. The PET resin in the base paper layer absorbs the water shell of the coated super-water-dispersible carbon black, not only increasing the moisture content of the substrate layer and further preventing cracking, but also leaving the space previously occupied by the water shell in the buffer layer vacant, forming holes. These holes differ from those in foam metal in that the water shell is absorbed by the PET resin, preventing air from entering the holes. Therefore, the holes create a vacuum-like atmosphere, creating negative pressure between the base paper layer and the buffer layer, increasing the bond strength between the substrate layer and the coating layer while also absorbing thermal expansion differences. Furthermore, acrylic-modified polyurethane resin is also a water-based resin, and coated super-water-dispersible carbon black has better dispersibility in acrylic-modified polyurethane resin than ordinary carbon black.

[0020] Coated super water-dispersible carbon black is a prior art. As a preferred method of the present invention, the coated super water-dispersible carbon black is prepared by the following steps: mixing carbon black with an anionic surfactant and then air-flow milling, so that the lipophilic end of the anionic surfactant is adsorbed to the surface of the carbon black. As a preferred method of the present invention, the anionic surfactant includes one or more selected from sodium N-acyl sarcosinate, sodium monolauryl phthalate, sodium monolauryl phthalate polyoxyethylene ether ester, sodium monolauryl maleate polyoxyethylene ether ester, sodium alkyl sulfonamide acetate, α-olefin sulfonate, sodium α-sulfo fatty acid methyl ester, sodium dibutylnaphthalene sulfonate, sodium N-oleoylmethyl taurate, sodium dodecylbenzenesulfonate, sodium dodecylnaphthalenesulfonate, sodium lauryl sulfate, sodium lauryl sulfate, polyoxyethylene ether phosphate, etc.

[0021] Another object of the present application is to provide a method for preparing explosion-proof colored metal brushed cigarette packaging paper, comprising the following steps: coating a buffer layer between the base paper layer and the metal layer, and then placing the layer in a laminating device for lamination.

[0022] As a preferred embodiment of the present invention, the lamination temperature is 40° C. to 100° C. By laminating under heating, the negative expansion material is in a volume contraction state, and then after cooling to room temperature, the core-shell structure expands and squeezes between the base paper layer and the metal layer, thereby improving the interlayer bonding strength between the base paper layer and the metal layer.

[0023] As a preferred embodiment of the present invention, the lamination time is 60s-240s, and the lamination pressure is 0.01MPa-0.03MPa. The pressure should not be too high to avoid rupture of the core-shell structure.

[0024] Beneficial effects of the present invention:

[0025] In this application, a buffer layer is used to mitigate the thermal expansion difference between the base paper layer and the metal layer. Specifically, under heated conditions, the negative expansion material core shrinks in volume due to heat, creating a gap between the plastic shell and the core. This gap accommodates the difference in thermal expansion through deformation and compression, while also reducing the contact area to reduce heat conduction and mitigate the effects of thermal expansion. This reduces stress concentration under heated conditions and prevents peeling between layers, or bulging of a layer with a high expansion coefficient or cracking of a layer with a low expansion coefficient. Under unheated conditions, the negative expansion material returns to its larger volume, filling the gap within the plastic shell. The resulting core-shell structure fills the gap between the base paper layer and the metal layer, preventing weakening of the overall packaging paper structure and improving the connection strength between the base paper layer and the metal layer. DETAILED DESCRIPTION

[0026] The following are specific embodiments of the present invention and further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0027] Example 1

[0028] An explosion-proof colored metal brushed cigarette wrapping paper is prepared by the following steps:

[0029] (1) Preparation of base paper layer: papermaking of bleached softwood kraft chemical pulp to prepare the base paper layer.

[0030] (2) Preparation of metal layer: Aluminum foil is used.

[0031] (3) Preparation of buffer layer: 0.2 mol / L ZrOCl2 solution and 0.2 mol / L Na2WO4 solution were simultaneously added dropwise to deionized water, heated in an oil bath at 60°C and stirred for 2 h. Then 6 mol / L hydrochloric acid solution was added, the temperature was raised to 90°C and the oil bath was heated for 3 h. After heating, the mixed solution was poured into a hydrothermal reactor, and the reactor was heated at 180°C and kept warm for 10 h. After 10 h, the solution in the reactor was filtered and dried to obtain a precursor. Finally, the precursor was calcined at 600°C for 6 h, quenched, filtered, dried, and collected to obtain ZrW2O8. According to parts by mass, 5 parts of terephthalic acid were dispersed in N,N-dimethylformamide, and then 1 part of ZrW2O8 powder was added. After ultrasonic dispersion for 10 minutes, condensed water was added under nitrogen protection. After reaction for 10 minutes, antimony trioxide catalyst, OP-10 emulsifier and 100 parts of ethylene glycol were added. After reaction at a constant temperature of 180°C for 7 hours, it was filtered and washed with anhydrous ethanol. The obtained solid was vacuum dried at 80°C to obtain a core-shell structure.

[0032] TDI was added to a 1:1 volume ratio of dimethyl sulfoxide and methyl isobutyl ketone (MIBK) in a mixed solvent, stirred, and heated to 60°C. Polyethylene glycol was then added dropwise, and the reaction continued at 60°C for 2 hours to obtain a prepolymer solution. AIBM, stearic acid, and acrylic acid were dissolved in the mixed solvent and added to the prepolymer solution. The temperature was gradually raised to 80°C and stirred at this constant temperature for 2 hours to obtain a polymer solution. The polymer solution was poured into distilled water to precipitate a solid product. The solid product was washed with water and ethanol and then dried under vacuum at 50°C to obtain an acrylic acid-grafted copolymer modified polyurethane resin.

[0033] According to parts by mass, 15 parts of the core-shell structure were dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin and set aside.

[0034] (4) After coating a buffer layer on the base paper layer, the metal layer is laminated; then the base paper is sent to a laminating device for lamination at a lamination temperature of 80°C, a lamination pressure of 0.02 MPa, and a lamination time of 120 seconds.

[0035] Example 2

[0036] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0037] In step (3), 15 parts of the core-shell structure are dispersed in 100 parts of polyurethane according to parts by mass and set aside.

[0038] Example 3

[0039] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0040] In step (3), 15 parts of the core-shell structure were dispersed in 100 parts of ethanol according to mass parts and set aside.

[0041] Example 4

[0042] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0043] In step (3), based on the steps of Example 1, the following steps are further included: polyol ether PPG-330, silicone stabilizer, triethylenediamine / stannous octoate, and pore opener are mixed uniformly and added to the components containing TDI, mixed uniformly, poured into a foaming box, and then aged at 100°C for 4 hours. The dried product is taken out and cut and crushed to obtain porous PU.

[0044] According to parts by mass, 15 parts of core-shell structure and 5 parts of porous PU are dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin and set aside.

[0045] Example 5

[0046] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0047] In step (3), based on the steps of Example 1, the following steps are further included: copper is put into a pit furnace, the temperature is raised to 1200°C, and then 2% by mass of calcium metal is added with stirring at a stirring speed of 600 r / min. When the melt has a certain viscosity, that is, there is a sense of resistance when stirring, the stirring speed is increased to 1200 r / min, and 1.5% by mass of TiH2 foaming agent is added. After stirring evenly, stirring is stopped, and the mixture is kept warm for foaming for 200 seconds to obtain foamed copper.

[0048] According to parts by mass, 15 parts of the core-shell structure and 5 parts of the foamed copper were dispersed in 100 parts of the acrylic acid graft copolymer modified polyurethane resin and set aside.

[0049] Example 6

[0050] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0051] In step (3), based on the steps of Example 1, the following steps are further included: putting aluminum into a pit furnace, heating it to 700°C, then stirring and adding 2% by mass of calcium metal, and the stirring speed is 600r / min. When the melt has a certain viscosity, that is, there is a sense of resistance when stirring, the stirring speed is increased to 1200r / min, and 1.5% by mass of TiH2 foaming agent is added. After stirring evenly, the stirring is stopped, and the foaming is kept warm for 200s to obtain foamed aluminum.

[0052] According to parts by mass, 15 parts of the core-shell structure and 5 parts of foamed aluminum were dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin and set aside.

[0053] Example 7

[0054] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0055] In step (1), 92 parts by mass of softwood bleached sulfate chemical pulp and 8 parts by mass of polyethylene terephthalate are mixed evenly and then sent to a surface screen for papermaking to obtain a base paper layer.

[0056] Example 8

[0057] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0058] In step (1), 92 parts by mass of softwood bleached sulfate chemical pulp and 8 parts by mass of polyethylene terephthalate are mixed evenly and then sent to a surface screen for papermaking to obtain a base paper layer.

[0059] In step (3), 15 parts of the core-shell structure were dispersed in 100 parts of ethanol according to mass parts and set aside.

[0060] Example 9

[0061] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0062] Step (3) also includes the following steps: mixing carbon black and sodium dodecylbenzene sulfonate in a mass ratio of 92:8 for 12 minutes to obtain a mixture, feeding the mixture into a fluidized bed air flow mill, wherein the crushing pressure of the fluidized bed air flow mill is 0.7 MPa, the classification speed is 200 r / min, and the air volume is 12.5 M 3 / min, and crushed for 2h to obtain coated super water-dispersible carbon black.

[0063] According to parts by mass, 15 parts of core-shell structure and 5 parts of coated super water-dispersible carbon black are dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin and set aside.

[0064] Example 10

[0065] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0066] In step (1), 92 parts by mass of softwood bleached sulfate chemical pulp and 8 parts by mass of polyethylene terephthalate are mixed evenly and then sent to a surface screen for papermaking to obtain a base paper layer.

[0067] Step (3) also includes the following steps: mixing carbon black and sodium dodecylbenzene sulfonate in a mass ratio of 92:8 for 12 minutes to obtain a mixture, feeding the mixture into a fluidized bed air flow mill, wherein the crushing pressure of the fluidized bed air flow mill is 0.7 MPa, the classification speed is 200 r / min, and the air volume is 12.5 M 3 / min, and crushed for 2h to obtain coated super water-dispersible carbon black.

[0068] According to parts by mass, 15 parts of core-shell structure and 5 parts of coated super water-dispersible carbon black are dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin and set aside.

[0069] Example 11

[0070] This embodiment is basically the same as the first embodiment, and the only difference is that:

[0071] In step (3), 15 parts of core-shell structure and 5 parts of carbon black are dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin according to mass parts and set aside.

[0072] Example 12

[0073] An explosion-proof colored metal brushed cigarette wrapping paper is prepared by the following steps:

[0074] (1) Preparation of base paper layer: 92 parts by weight of softwood bleached sulfate chemical pulp and 8 parts by weight of polyethylene terephthalate were mixed evenly and then sent to a surface screen for papermaking to prepare a base paper layer.

[0075] (2) Preparation of metal layer: Aluminum foil is used.

[0076] (3) Preparation of buffer layer: 0.2 mol / L ZrOCl2 solution and 0.2 mol / L Na2WO4 solution were simultaneously added dropwise to deionized water, heated in an oil bath at 60°C and stirred for 2 h. Then 6 mol / L hydrochloric acid solution was added, the temperature was raised to 90°C and the oil bath was heated for 3 h. After heating, the mixed solution was poured into a hydrothermal reactor, and the reactor was heated at 180°C and kept warm for 10 h. After 10 h, the solution in the reactor was filtered and dried to obtain a precursor. Finally, the precursor was calcined at 600°C for 6 h, quenched, filtered, dried, and collected to obtain ZrW2O8. According to parts by mass, 5 parts of terephthalic acid were dispersed in N,N-dimethylformamide, and then 1 part of ZrW2O8 powder was added. After ultrasonic dispersion for 10 minutes, condensed water was added under nitrogen protection. After reaction for 10 minutes, antimony trioxide catalyst, OP-10 emulsifier and 100 parts of ethylene glycol were added. After reaction at a constant temperature of 180°C for 7 hours, it was filtered and washed with anhydrous ethanol. The obtained solid was vacuum dried at 80°C to obtain a core-shell structure.

[0077] TDI was added to a 1:1 volume ratio of dimethyl sulfoxide and methyl isobutyl ketone (MIBK) in a mixed solvent, stirred, and heated to 60°C. Polyethylene glycol was then added dropwise, and the reaction continued at 60°C for 2 hours to obtain a prepolymer solution. AIBM, stearic acid, and acrylic acid were dissolved in the mixed solvent and added to the prepolymer solution. The temperature was gradually raised to 80°C and stirred at this constant temperature for 2 hours to obtain a polymer solution. The polymer solution was poured into distilled water to precipitate a solid product. The solid product was washed with water and ethanol and then dried under vacuum at 50°C to obtain an acrylic acid-grafted copolymer modified polyurethane resin.

[0078] Aluminum is put into a pit furnace, heated to 700°C, then stirred and 2% by mass of calcium metal is added at a stirring speed of 600r / min. When the melt has a certain viscosity, that is, there is a sense of resistance when stirring, the stirring speed is increased to 1200r / min, and 1.5% by mass of TiH2 foaming agent is added. After stirring evenly, stirring is stopped, and the mixture is kept warm for foaming for 200s to obtain foamed aluminum.

[0079] Carbon black and sodium dodecylbenzenesulfonate were mixed in a mass ratio of 92:8 and stirred for 12 minutes to obtain a mixture, which was then fed into a fluidized bed jet mill with a crushing pressure of 0.7 MPa, a classification speed of 200 r / min, and an air volume of 12.5 M 3 / min, and crushed for 2h to obtain coated super water-dispersible carbon black.

[0080] According to parts by mass, 15 parts of core-shell structure, 5 parts of foamed aluminum, and 5 parts of coated super water-dispersible carbon black are dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin and set aside.

[0081] (4) After coating a buffer layer on the base paper layer, the metal layer is laminated; then the base paper is sent to a laminating device for lamination at a lamination temperature of 80°C, a lamination pressure of 0.02 MPa, and a lamination time of 120 seconds.

[0082] Comparative Example 1

[0083] This comparative example is basically the same as Example 1, except that:

[0084] 100 parts of acrylic acid graft copolymer modified polyurethane resin is used as the buffer layer.

[0085] Comparative Example 2

[0086] This comparative example is basically the same as Example 1, except that:

[0087] According to parts by mass, 15 parts of ZrW2O8 were dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin to serve as a buffer layer.

[0088] Comparative Example 3

[0089] This comparative example is basically the same as Example 1, except that:

[0090] According to parts by mass, 1 part of terephthalic acid was dispersed in N,N-dimethylformamide, and ultrasonically dispersed for 10 minutes. Then, condensed water was added under nitrogen protection. After reacting for 10 minutes, antimony trioxide catalyst, OP-10 emulsifier and 20 parts of ethylene glycol were added. After reacting at a constant temperature of 180°C for 7 hours, the mixture was filtered and washed with anhydrous ethanol. The obtained solid was vacuum dried at 80°C to obtain PET.

[0091] According to parts by mass, 15 parts of PET were dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin to serve as a buffer layer.

[0092] Comparative Example 4

[0093] This comparative example is basically the same as comparative example 3, except that:

[0094] According to parts by mass, 15 parts of ZrW2O8 prepared in Example 1 and 15 parts of PET were dispersed in 100 parts of acrylic acid graft copolymer modified polyurethane resin to serve as a buffer layer.

[0095] Thermal expansion testing

[0096] The wrapping papers prepared in the examples and comparative examples were subjected to heat treatment, and the temperature at which bulges or cracks appeared on the wrapping papers was recorded. The test results are shown in Table 1 below.

[0097] Internal bonding strength test

[0098] The packaging papers prepared in the examples and comparative examples were tested for internal bond strength using GB / T 26203-2010 Paper and paperboard - Determination of internal bond strength (Scott type). The test results are shown in Table 1 below.

[0099] Table 1.

[0100]

[0101] As shown in Table 1, a comparison of Example 1 with Comparative Examples 1-4 demonstrates that the core-shell negative expansion material introduced between the base paper layer and the metal layer effectively alleviates the thermal expansion coefficient mismatch between the two layers, improving the heat resistance of the wrapping paper while also enhancing the bonding strength between the two layers. Comparative Examples 2 and 4 also incorporate negative expansion material, but lack a wall material separating the negative expansion material from the adhesive. When heated, the contraction of the negative expansion material causes the entire buffer layer to contract, widening the thermal expansion gap between the base paper layer and the metal layer.

[0102] By comparing Example 1 with Examples 4-6, it can be seen that the foam matrix has a positive effect on solving the problem of thermal expansion coefficient mismatch between the base paper layer and the metal layer. Among them, when aluminum foil is used for the metal layer, foam aluminum is the best. However, the pore structure based on the foam may cause the bonding strength between the base paper layer and the metal layer to be reduced.

[0103] By comparing Example 3 and Example 8, and Example 1 and Example 7, it can be seen that the use of PET in the base paper layer can improve the flexibility of the matrix layer and alleviate the cracking of the base paper layer; at the same time, the improvement effect of the combination of PET in the base paper layer and acrylic acid graft copolymer modified polyurethane resin in the buffer layer is better than the improvement effect of PET in the base paper layer and ethanol in the buffer layer, indicating that the combination of PET and acrylic acid graft copolymer modified polyurethane resin has a certain synergistic effect on improving the internal bonding strength.

[0104] A comparison of Example 1 with Examples 9 and 11 reveals that carbon black has a certain degree of thermal conductivity, which helps disperse heat within the buffer layer, enhancing its cushioning effect. Furthermore, the coated super-water-dispersible carbon black has better dispersibility than carbon black, resulting in a more effective improvement. Furthermore, a comparison with Example 10 reveals that the combination of acrylic acid-grafted copolymer-modified polyurethane resin and coated super-water-dispersible carbon black with a PET matrix layer is even more effective in improving thermal expansion and enhancing bonding strength.

[0105] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. An explosion-proof metallic brushed cigarette wrapping paper, characterized by: The invention comprises a base paper layer, a buffer layer and a metal layer arranged in sequence; the buffer layer comprises a core-shell structure with a plastic material as a shell and a negative expansion material as a core; the negative expansion material is selected from a material having negative expansion characteristics within the range of 0°C-100°C; The plastic material includes one or more of polyvinyl alcohol, polyester, polyurethane, polyamide, polylactic acid, and polypropylene; The preparation of the explosion-proof colored metal drawing cigarette packaging paper comprises the following steps: coating a buffer layer between the base paper layer and the metal layer, and then placing the paper in a laminating device for lamination at a lamination temperature of 40°C-100°C.

2. The explosion-proof colored metal brushed cigarette wrapping paper according to claim 1, characterized in that: The negative expansion material includes one or more of PbTiO3, ZrW2O8, and HfW2O8.

3. The explosion-proof colored metallic brushed cigarette wrapping paper according to claim 1, characterized in that: The cushioning layer also includes a foam matrix.

4. The explosion-proof colored metallic brushed cigarette wrapping paper according to claim 3, characterized in that: The foam matrix is ​​foam metal.

5. The explosion-proof colored metallic brushed cigarette wrapping paper according to claim 4, characterized in that: The metal used for the metal foam is consistent with the metal used for the metal layer.

6. The explosion-proof colored metallic brushed cigarette wrapping paper according to claim 1, characterized in that: The buffer layer further includes an adhesive, and the core-shell structure is dispersed in the adhesive.

7. The explosion-proof colored metallic brushed cigarette wrapping paper according to claim 6, characterized in that: The adhesive comprises acrylic acid graft copolymer modified polyurethane resin.

8. The explosion-proof colored metallic brushed cigarette wrapping paper according to claim 1 or 7, characterized in that: The base paper layer includes polyethylene terephthalate.

9. The explosion-proof colored metallic brushed cigarette wrapping paper according to claim 7, characterized in that: The buffer layer further comprises coated super water-dispersible carbon black.

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