阅读说明：本技术 一种无铝内衬纸的制备方法 (Preparation method of aluminum-free lining paper ) 是由 史君齐 江晓明 戴贤中 路崇斌 吴朋飞 罗天宝 于 2020-05-11 设计创作，主要内容包括：本发明涉及卷烟包装材料技术领域,针对内衬纸阻隔性、光泽度不佳的问题,提供一种无铝内衬纸的制备方法,在涂料罐中加入聚乙烯醇溶液和含有碳酸钙的改性云母粉,超声分散后调至酸性,再加水溶性壳聚糖、结冷胶水溶液加热搅拌得面涂层涂料；以水性环保涂料为背涂层涂料；原纸通过涂布机在两面分别涂布面涂层涂料和背涂层涂料,再经抹平辊、烘箱得到无铝内衬纸。本发明聚乙烯醇和水溶性壳聚糖交联形成致密网络结构,改性云母石提高面涂层光泽度,碳酸钙使改性云母石分散均匀,酸化处理后还能促进交联、诱导结冷胶形成致密网状结构,提高面涂层的阻隔性。(The invention relates to the technical field of cigarette packaging materials, and provides a preparation method of an aluminum-free lining paper aiming at the problems of poor barrier property and poor glossiness of the lining paper, wherein a coating tank is added with a polyvinyl alcohol solution and modified mica powder containing calcium carbonate, the mixture is subjected to ultrasonic dispersion and then is adjusted to be acidic, and then a water-soluble chitosan and gellan gum aqueous solution are added, heated and stirred to obtain a surface coating paint; taking a water-based environment-friendly coating as a back coating; and respectively coating surface coating paint and back coating paint on two sides of the base paper by a coating machine, and then obtaining the aluminum-free lining paper by a troweling roller and an oven. According to the invention, polyvinyl alcohol and water-soluble chitosan are crosslinked to form a compact network structure, the modified mica stone improves the glossiness of the surface coating, the calcium carbonate enables the modified mica stone to be uniformly dispersed, and the crosslinking and the gellan gum induction can be promoted to form the compact network structure after the acidification treatment, so that the barrier property of the surface coating is improved.)

1. The preparation method of the aluminum-free lining paper is characterized by comprising the following steps of: (1) preparing a top coating paint: adding 4-6% by mass of polyvinyl alcohol aqueous solution and modified mica powder into a coating tank, wherein the modified mica powder contains calcium carbonate, adjusting the pH to 3-5 after ultrasonic dispersion, continuing ultrasonic treatment for 10-30min, adding water-soluble chitosan, uniformly stirring, adding 0.5-0.8% by mass of gellan gum aqueous solution, and uniformly stirring at 60-70 ℃ to obtain a surface coating;

(2) preparing a back coating paint: taking a water-based environment-friendly coating as a back coating;

(3) coating and processing: and (3) respectively coating surface coating paint and back coating paint on the two sides of the base paper on the unreeling machine through two coating machines in sequence, enabling the thickness of the paint to be uniform through a leveling roller, and then drying through an oven to enable the paint to be cured to obtain the aluminum-free lining paper.

2. The method for preparing the aluminum-free lining paper as claimed in claim 1, wherein the aluminum-free lining paper comprises, by mass, 20-40 parts of polyvinyl alcohol, 40-60 parts of modified mica powder, 2-4 parts of water-soluble chitosan, and 0.05-0.16 part of gellan gum.

3. The method for preparing aluminum-free liner paper according to claim 1 or 2, wherein the particle size of the modified mica powder is controlled to be less than 2 μm and accounts for more than 50%.

4. The method for preparing the aluminum-free lining paper as claimed in claim 3, wherein the modified mica powder is prepared by the following steps: 1) dispersing a titanate coupling agent in white oil with equal mass, adding mica powder, stirring and heating the mixture for reaction at 70-90 ℃ for 10-20min, wherein the use amount of the titanate coupling agent is 1-1.5% of the mass of the mica powder;

2) adding calcium carbonate into the reaction product, stirring and standing, wherein the using amount of the calcium carbonate is 2-4.5% of the mass of the mica powder, and the particle size of the calcium carbonate powder is 700-900 nm;

3) and grinding after ultrasonic dispersion to obtain the modified mica powder.

5. The method of claim 1, wherein the water-based environmental protective coating is a water-soluble acrylate coating.

6. The method for preparing aluminum-free liner paper according to claim 1, wherein the coating is applied by a doctor blade, and the coating amount is as follows: front surface 6-10g/m²And the reverse side is 3-5g/m²。

7. The method for preparing aluminum-free liner paper according to claim 1, 5 or 6, wherein the raw paper in step (3) is further subjected to supercalendering, edge cutting, pattern printing by a rotary press and slitting in sequence after being dried by the oven, and finally the aluminum-free liner paper is obtained.

Technical Field

The invention relates to the technical field of cigarette packaging materials, in particular to a preparation method of aluminum-free lining paper.

Background

The cigarette lining paper is the packing paper lined in the inner layer of the soft cigarette box or the hard cigarette box, is used as the initial packing layer of the cigarette, plays the roles of separating fragrance, moisture, shading and the like, and simultaneously shows the aesthetic property. The types of lining paper are various, and at present, rolled aluminum foil composite lining paper or vacuum aluminized lining paper is mostly adopted.

The rolled aluminum foil paper is formed by rolling a paper base, an adhesive and an aluminum foil, has high barrier property and corrosion resistance to water, gas and light, does not deform when the temperature changes rapidly, and is widely used as the cigarette lining paper at present. The production process is that the aluminum foil and the paper are jointed by a wet method by adopting a roll coating method, and water-soluble (or adhesive taking water as dispersibility) with proper viscosity or concentration is prepared and uniformly and quantitatively coated on the first base material aluminum foil. The adhesive layer was bonded to a second substrate (porous highly absorbent interleaving paper) by a bonding roll in a wet state. However, the calendered aluminum foil composite lining paper cannot be degraded after being used, so that environmental pollution can be caused, and the aluminum foil is very thin and difficult to recycle, so that huge waste of resources is caused.

The vacuum aluminized paper is produced by a direct spraying method or a transfer method, has thin and uniform aluminum film and good optical effect, has good shielding and reflecting effects on light, ultraviolet rays and the like, and can effectively prevent the aging of the contents of the cut tobacco by the light. The production process is that the roll paper or other base materials are arranged on a vacuum aluminum plating machine for direct aluminum plating, the vacuum aluminum plating machine is high in cost and huge in power consumption, the production cost of products is further high, meanwhile, the vacuum direct plating paper has strict requirements on paper bases, only imported base paper can be used, the requirements of matched equipment are extremely strict, and the high power consumption is not suitable for the current energy-saving and environment-friendly industrial policy.

The two processes need to consume metal aluminum, and from the aspects of reducing production cost, protecting environment and sustainable development, the coating material of the lining paper for the cigarettes is advocated and guided to be developed towards the direction of easy degradation and more economy. At present, the improvement of the production method of the aluminum-free lining paper for the domestic cigarettes is relatively lagged, Chinese patent CN102127879A proposes a coating and perfuming environment-friendly cigarette lining paper, one side or two sides of the lining paper base paper are coated with a coating liquid which takes a tobacco extract as a main raw material, so that the cigarettes can be prevented from being damp and keep the fragrance, and the fragrance in the cigarette case can be full through volatilizing the natural cigarette fragrance, thereby increasing the cigarette smell and improving the smoking taste. However, the patent mainly emphasizes that the fragrance of the lining paper is increased, the lining paper coating technology is single, and the problems of improving the barrier property of the lining paper, increasing the metal texture and the like are not involved, so that an ideal solution is needed.

Disclosure of Invention

The invention aims to solve the problems of poor barrier property and poor metal texture of the lining paper for cigarettes in the prior art, and provides a preparation method of the aluminum-free lining paper.

In order to achieve the purpose, the invention adopts the following technical scheme: a preparation method of aluminum-free lining paper comprises the following steps: (1) preparing a top coating paint: adding 4-6% by mass of polyvinyl alcohol aqueous solution and modified mica powder into a coating tank, wherein the modified mica powder contains calcium carbonate, adjusting the pH to 3-5 after ultrasonic dispersion, continuing ultrasonic treatment for 10-30min, adding water-soluble chitosan, uniformly stirring, adding 0.5-0.8% by mass of gellan gum aqueous solution, and uniformly stirring at 60-70 ℃ to obtain a surface coating;

(2) preparing a back coating paint: taking a water-based environment-friendly coating as a back coating;

(3) coating and processing: and (3) respectively coating surface coating paint and back coating paint on the two sides of the base paper on the unreeling machine through two coating machines in sequence, enabling the thickness of the paint to be uniform through a leveling roller, and then drying through an oven to enable the paint to be cured to obtain the aluminum-free lining paper.

The surface coating of the invention adopts polyvinyl alcohol as a raw material, has excellent adhesive force on the surface of paper, has no peculiar smell and no toxicity, takes water as a solvent, and is safe and environment-friendly. The mica powder is added to endow the surface coating with metallic luster, so that the surface coating has a silver gray metallic texture effect, and meanwhile, the unique two-dimensional flaky barrier property, the stability of a chemical structure and other properties of the mica powder effectively improve the anti-permeability of the coating. The modified mica powder contains calcium carbonate, and the calcium carbonate is decomposed into CO after acid treatment₂And Ca²⁺，CO₂The gas escapes to form pores or grooves in the polyvinyl alcohol molecular structure, so that the modified mica powder can enter the polyvinyl alcohol molecular structure, and the modified mica powder is dispersed more uniformly. The molecular weight of the polyvinyl alcohol is 17-22 ten thousand, the molecular weight of the water-soluble chitosan is 5-9 ten thousand, the water-soluble chitosan can be filled into a network structure of the polyvinyl alcohol, hydroxyl and amino in the water-soluble chitosan can form hydrogen bonds with the hydroxyl of the polyvinyl alcohol, the polyvinyl alcohol and the water-soluble chitosan form a compact network structure after cross-linking, and the coating has good barrier property to water vapor and air and improves the barrier property of the coating. Ca²⁺The size is small, the chitosan can be freely and flexibly dispersed in the molecular structure of polyvinyl alcohol, the nature of cations enhances the intermolecular hydrogen bond and electrostatic attraction effect, and the hydrogen bond crosslinking strength of hydroxyl groups, amino groups and the hydroxyl groups of the polyvinyl alcohol in the water-soluble chitosan can be promoted, so that the viscosity of the system is improved. Finally adding gellan gum in Ca²⁺Inducing to form a compact three-dimensional network structure, covering the outermost side, and filling CO before filling₂The gas escapes from the molecular structure of the polyvinyl alcohol to form pores, and a stable compact film layer is formed. The gellan gum has good transmittance and is not easy to influence modificationGloss of mica powder.

Preferably, 20-40 parts of polyvinyl alcohol, 40-60 parts of modified mica powder, 2-4 parts of water-soluble chitosan and 0.05-0.16 part of gellan gum. The excessive use amount of the modified mica powder can affect the strength of film formation, so that the control is required to be in a reasonable range. The excessive consumption of the gellan gum can cause unnecessary waste, and the gel thickness can influence the glossiness to a certain extent, so that the reasonable consumption of the gellan gum can be screened out by the inventor through experiments.

Preferably, the particle size of the modified mica powder is controlled to 2 μm or less and is 50% or more. The control of the particle size of the modified mica powder can increase the fineness of the coating, so that the leveling property of the coating in the coating process is better.

Preferably, the preparation method of the modified mica powder comprises the following steps:

1) dispersing a titanate coupling agent in white oil with equal mass, adding mica powder, stirring and heating the mixture for reaction at 70-90 ℃ for 10-20min, wherein the use amount of the titanate coupling agent is 1-1.5% of the mass of the mica powder;

2) adding calcium carbonate into the reaction product, stirring for 5min, and standing for 2h, wherein the use amount of the calcium carbonate is 2-4.5% of the mass of the mica powder, and the particle size of the calcium carbonate powder is 700-900 nm;

3) and grinding after ultrasonic dispersion to obtain the modified mica powder.

The titanate coupling agent is coated on the surface of the mica powder particles, and can be combined with polyvinyl alcohol through chemical reaction, so that the compatibility of the mica powder and the polyvinyl alcohol is improved. The nano-scale calcium carbonate is dispersed among the mica powder, so that the modified mica powder with small particle size can be obtained by grinding, and the modified mica powder particles are prevented from reunited. Wherein, the particle size and the dosage of the calcium carbonate can influence the film forming performance and are a numerical range obtained after the best screening.

Preferably, the water-based environment-friendly coating is a water-soluble acrylate coating. The water-soluble acrylate coating is prepared from copolymer resin with active crosslinkable functional groups, can be crosslinked to form a compact film with a three-dimensional structure during film forming, and has good film forming and barrier properties.

Preferably, the coating is applied by a doctor blade, the amount of coating applied: front surface 6-10g/m²And the reverse side is 3-5g/m². The scraper coating does not require the coating to be soft and have strong fluidity, is suitable for coating the coating containing the modified mica powder, and ensures that the coating is uniform in the coating process.

Preferably, after the raw paper in the step (3) is dried by the oven, the raw paper is sequentially subjected to the steps of supercalendering, edge cutting, pattern printing by a rotary printing machine and slitting, and finally the aluminum-free lining paper is obtained. Compared with the common calendering roller, the supercalendering process has more rollers and large line pressure, and can obtain higher smoothness and glossiness.

Therefore, the beneficial effects of the invention are as follows: the polyvinyl alcohol is added with water-soluble chitosan to form a compact network structure through mutual crosslinking, the modified mica stone is also added to endow a surface coating with metal luster, the modified mica stone can be dispersed more uniformly by containing calcium carbonate, the crosslinking and the induced gellan gum can be promoted to form a compact three-dimensional network structure after the acidification treatment, the surface coating is covered on the outermost side, the polyvinyl alcohol is improved to be added with the water-soluble chitosan to form the compact network structure through mutual crosslinking, the modified mica stone is also added to endow the surface coating with the metal luster, the modified mica stone can be dispersed more uniformly by containing the calcium carbonate, the crosslinking and the induced gellan gum can be promoted to form the compact three-dimensional network structure after the acidification treatment, the surface coating is covered on the outermost side, and the barrier property of the surface coating is improved.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific examples.

In the present invention, unless otherwise specified, all the raw materials and equipment used are commercially available or commonly used in the art, and the methods in the examples are conventional in the art unless otherwise specified.