Preparation method and application of flame-retardant coating

Abstract

The invention discloses a preparation method and application of a flame-retardant coating, and relates to the technical field of flame-retardant coatings for special papers.The flame-retardant coating is prepared from, by weight, 80-85 parts of flame-retardant pigment and 15-20 parts of heat insulation pigment; the total weight of the components is set as M, the adhesive accounts for 8-15% M, the co-adhesive accounts for 7-9% M, the thickening agent accounts for 1-2% M, the lubricant accounts for 0.6-1% M, the water repellent agent accounts for 0.5-0.8% M, the defoaming agent accounts for 0.1-0.2% M, and the dispersing agent accounts for 0.2-0.3% M. The flame-retardant coating is designed and prepared, and the tipping base paper which can be carbonized at high temperature and does not burn is prepared by coating the surface of the tipping base paper. The preparation method is simple in process and high in operability, the defects of a direct papermaking method and an in-pulp addition method are overcome, the production efficiency and the resource utilization rate are improved, and the production cost is reduced. The flame-retardant tipping base paper is prepared by a coating method instead of a traditional in-pulp addition method, and a functional coating is selected and designed, so that the coating process flow and parameters are determined. The flame-retardant coating prepared by the invention endows tipping base paper with excellent high-temperature carbonization and non-combustion performance, and the flame safety performance of the tipping base paper is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant coatings for special papers, and in particular to a preparation method of a flame retardant coating and application thereof. Background Art

[0002] As a special industrial paper used for cigarettes, cork base paper is very easy to come into contact with fire during use, so its fire safety is extremely important. At present, the commonly used method for preparing flame-retardant paper is mainly to add inorganic fillers into the pulp, but the in-slurry addition method makes it difficult to evenly disperse the added fillers, and at the same time causes the slurry's water filtration rate to be significantly reduced, thereby affecting production efficiency and increasing production costs. In addition, the flame-retardant paper produced by the in-slurry addition method has a significant decrease in mechanical properties due to the destruction of internal hydrogen bonds, which makes it difficult to meet actual needs in certain application fields.

[0003] The coating method refers to applying a coating on the surface of base paper to give the paper corresponding functions. The coating used in this method is often mainly composed of flame retardant pigments and heat-insulating pigments, and is prepared by adding various functional fillers and corresponding additives and water. This method not only avoids the shortcomings of adding pulp, but also has a simple preparation process, high resource utilization, and environmental friendliness. Therefore, the use of surface coating method to prepare flame-retardant paper has a good development prospect.

[0004] However, the coatings currently used in the market based on the coating method still have certain limitations in terms of flame retardant properties. Although these coatings can achieve flame retardant effects to a certain extent, in some special high-temperature environments, especially in the extremely high-temperature conditions that may be encountered in the field of cigarette production, ordinary coated paper coatings cannot meet the extremely strict requirement of high-temperature carbonization without burning.

[0005] In actual applications, when exposed to high temperatures, the protective layer formed by the existing coated paper coating is prone to partial carbonization and continued burning, which undoubtedly poses a serious safety hazard to the cigarette production process. In addition, with the continuous improvement of industrial safety standards and people's increasing attention to fire safety, the flame retardant performance requirements for special industrial papers such as kraft paper are becoming increasingly stringent.

[0006] At present, there is a lack of a flame-retardant coated paper coating with high-temperature carbonization and non-combustion characteristics specifically for kraft paper. This coating needs to be able to quickly form a stable and dense carbonization layer under high temperature conditions. The carbonization layer should not only effectively block the transfer of heat and prevent the paper from further burning, but also have good adhesion to ensure that it will not fall off due to friction, moisture and other factors during production, transportation and use, thereby truly ensuring the absolute safety of kraft paper when it comes into contact with a fire source and meeting the urgent needs of related industrial fields such as cigarette production. At the same time, this coating should reduce costs as much as possible during the preparation process and reduce the impact on the environment to meet the industrial concept of sustainable development. Summary of the invention

[0007] In order to solve the above problems, that is, to solve the problems raised by the above background technology, the present invention proposes a method for preparing a flame retardant coating and its application, which comprises the following raw materials in parts by weight: 80-85 parts of flame retardant pigments, 15-20 parts of heat-insulating pigments; the total weight of the above components is taken as a basis, set as M, the adhesive is 8-15%M, the co-adhesive is 7-9%M, the thickener is 1-2%M, the lubricant is 0.6-1%M, the water repellent is 0.5-0.8%M, the defoamer is 0.1-0.2%M, and the dispersant is 0.2-0.3%M.

[0008] The present invention is further configured as follows: the flame retardant pigment includes but is not limited to one or more mixtures of hydroxyapatite, aluminum hydroxide, magnesium hydroxide, wollastonite, hydrotalcite, kaolin, talc, sericite or zinc borate; wherein aluminum hydroxide, magnesium hydroxide, hydrotalcite and zinc borate absorb heat when heated and decomposed, inhibiting the thermal degradation of the fiber and thus delaying the generation of combustible gas; at the same time, the water vapor and other refractory gases released by decomposition can dilute the concentration of oxygen and combustible gas around the paper, so that the paper does not burn. Hydroxyapatite, wollastonite, kaolin, talc and sericite can catalyze the degradation of cellulose into carbon, while improving the strength and thermal stability of the residual carbon, thereby inhibiting the combustion. The heat-insulating pigment includes but is not limited to one or more mixtures of calcined diatomaceous earth, microporous calcium silicate or expanded perlite powder; it inhibits the expansion of carbonized holes by preventing heat from diffusing to the outer circle of the paper. The adhesive includes but is not limited to one or more mixtures of carboxylated styrene butadiene latex, hydroxylated styrene butadiene latex or acrylic emulsion; used to enhance the cohesion and tensile strength of paper, making the paper more stable. The co-adhesive includes but is not limited to one or a mixture of oxidized starch or polyvinyl alcohol; used to improve the smoothness and glossiness of the paper surface coating, while enhancing the mechanical strength of the paper. The thickener includes but is not limited to one or a mixture of carboxymethyl cellulose or sodium carboxymethyl cellulose; used to improve the coating quality and uniformity, and enhance the adhesion of the coating. The lubricant includes but is not limited to one or more mixtures of stearic acid glyceryl ester, polyoxyethylene ether or oleic acid; used to improve the fluidity and lubricity of the coating, and give the coating smoothness and gloss. The water repellent includes but is not limited to one or more mixtures of polyamide polyurea water repellent, potassium zirconium carbonate type water repellent, modified glyoxal resin or starch water repellent; used to improve the waterproof and water-resistant properties of paper. The defoamer includes but is not limited to one or more mixtures of emulsified silicone oil, polyoxypropylene glycerol ether, polyoxypropylene polyoxyethylene glycerol ether or polydimethylsiloxane; it is used for rapid defoaming, improving coating performance, and increasing gloss and smoothness. The dispersant includes but is not limited to one or a mixture of polyacrylamide or starch modifier, it is used to improve the dispersibility of the pigment, ensure that the coating does not flocculate and settle, and has good fluidity.

[0009] The present invention is further configured as follows: comprising the following steps: S1, adding dispersant, flame retardant pigment and heat-insulating pigment to water in accordance with the proportion, stirring evenly at room temperature with a high-speed disperser for use; the speed range of the high-speed disperser is 1950~2050r / min, preferably 1980r / min. S2, mixing thickener and water in accordance with the proportion, stirring at room temperature under a low-speed stirrer until completely dissolved for use; S3, mixing co-adhesive and water in accordance with the proportion, heating in a constant temperature water bath and stirring at a low speed until transparent for use; S4, adding the above-prepared flame retardant pigment solution, heat-insulating pigment mixed solution, adhesive, co-adhesive solution, thickener solution, lubricant, water repellent, defoamer and water in accordance with the proportion in order to shear and disperse, and finally obtaining a uniformly mixed flame retardant coating; the speed range of the high-speed shear is 1150~1250r / min, preferably 1200r / min.

[0010] The present invention is further configured as follows: the viscosity of the flame retardant coating is 400-700 cp.

[0011] The present invention is further configured as follows: the flame retardant coating is coated on the kraft paper by a surface coating method, comprising the following steps: S1, laying the kraft paper flat and fixing it on a panel of a semi-automatic coating machine; S2, evenly distributing the prepared flame retardant coating on the paper base 1 cm away from the front end of the Meyer winding rod; S3, setting the speed of the coating machine to 4 m / min, and driving the Meyer winding rod to evenly coat the flame retardant coating on the paper; S4, after natural drying, obtaining a flame retardant coated paper having high temperature carbonization and non-combustion properties.

[0012] The invention is further configured as follows: the basis weight range of the tipping base paper is 30-47 g / m 2 The water absorption Cobb60 of the smooth surface of the tipping paper is in the range of 20 to 35 g / m 2 .

[0013] The present invention is further configured as follows: when the flame retardant coating is applied to the tipping paper, the coating amount is 3-5 g / m 2 .

[0014] The beneficial technical effects of the present invention are as follows: the present invention designs and prepares a flame-retardant coating, and by coating the surface of the cork paper, a cork paper that can be carbonized at high temperature but does not burn is obtained. This preparation method has a simple process and strong operability, which not only avoids the shortcomings of the direct papermaking method and the in-slurry addition method, but also improves production efficiency and resource utilization, and reduces production costs. The present invention replaces the traditional in-slurry addition method with a coating method to prepare flame-retardant cork paper, selects and designs functional coatings, and determines the coating process flow and parameters. The flame-retardant coating prepared by the present invention gives the cork paper excellent high-temperature carbonization and non-combustion properties, effectively improving the fire safety performance of the cork paper.

[0015] The flame retardant pigments involved in the present invention include but are not limited to one or more mixtures of hydroxyapatite, aluminum hydroxide, magnesium hydroxide, wollastonite, hydrotalcite, kaolin, talc, sericite or zinc borate. Among them, aluminum hydroxide, magnesium hydroxide, hydrotalcite and zinc borate decompose and absorb heat, which can hinder the degradation of fibers and thus inhibit the escape of combustible gases; at the same time, the released water vapor and other flame retardant gases can dilute the concentration of oxygen and combustible gases, so that the paper does not burn. Hydroxyapatite, wollastonite, kaolin, talc and sericite and other materials can catalyze the degradation of fibers into carbon, improve the strength and thermal stability of the residual carbon, and inhibit the combustion. The heat-insulating pigments involved include but are not limited to one or more mixtures of calcined diatomaceous earth, microporous calcium silicate or expanded perlite powder. It can inhibit the expansion of carbonized holes by preventing heat from diffusing to the outer circle of the paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The flame retardant test effect diagram of the flame retardant tipping base paper in Example 1 is shown.

[0017] Figure 2 The flame retardant test effect diagram of the flame retardant tipping base paper in Example 2 is shown.

[0018] Figure 3 The flame retardant test effect diagram of the flame retardant coring base paper in Example 3 is shown.

[0019] Figure 4 The flame retardant test effect diagram of the flame retardant tipping base paper in Example 4 is shown. DETAILED DESCRIPTION

[0020] Please refer to the attached Figure 1-4 Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention. Example

[0021] Preparation of flame retardant coatings: S1. First, add 1.5g polyacrylamide and 500g hydroxyapatite to 205g water in sequence, and stir evenly at room temperature at a speed of 1980r / min using a high-speed disperser for later use; S2, add 15g carboxymethyl cellulose to 285g water, stir at room temperature under a low speed stirrer until completely dissolved and set aside; S3, add 80g of oxidized starch to 187g of water, heat to 95°C in a constant temperature water bath, stir at a low speed until transparent, and set aside; S4. Add the above-prepared 170g hydroxyapatite solution, 210g water, 30g prepared carboxymethyl cellulose solution, 44g prepared gelatinized starch, 12g carboxylated styrene butadiene latex, 1g glyceryl stearate, 2g polyamide polyurea water repellent, and 0.1g emulsified silicone oil into a high-speed shearing machine in sequence and shear and disperse at a speed of 1200r / min to finally obtain a uniformly mixed flame retardant coating.

[0022] Preparation of flame retardant coated paper: S1. Lay the base paper flat and fix it on the panel of the semi-automatic coating machine, and coat it; S2, first evenly distribute the prepared flame retardant coating on the paper base 1 cm away from the front end of the Meyer winding rod; S3, set the speed of the coating machine to 4m / min, and drive the Mayer winding rod to evenly coat the flame retardant coating on the paper, with a coating amount of 3g / m 2 ; S4. After natural drying, a flame retardant coated paper with high temperature carbonization but no combustion is obtained.

[0023] Embodiment 2: Preparation of flame retardant coatings: S1. First, add 1.5g polyacrylamide and 500g magnesium aluminum hydrotalcite into 205g water in sequence, and stir evenly at room temperature at a speed of 1980r / min using a high-speed disperser for later use; S2, add 15g carboxymethyl cellulose to 285g water, stir at room temperature under a low speed stirrer until completely dissolved and set aside; S3, add 80g of oxidized starch to 187g of water, heat to 95°C in a constant temperature water bath, stir at a low speed until transparent, and set aside; S4. Add the above-prepared 170g magnesium aluminum hydrotalcite solution, 210g water, 30g prepared carboxymethyl cellulose solution, 44g prepared gelatinized starch, 12g carboxylated styrene butadiene latex, 1g stearic acid glyceryl ester, 2g polyamide polyurea water repellent, and 0.1g emulsified silicone oil into a high-speed shearing machine in sequence and shear and disperse at a speed of 1200r / min to finally obtain a uniformly mixed flame retardant coating.

[0024] Preparation of flame retardant coated paper: S1. Lay the base paper flat and fix it on the panel of the semi-automatic coating machine, and coat it; S2, first evenly distribute the prepared flame retardant coating on the paper base 1 cm away from the front end of the Meyer winding rod; S3, set the speed of the coating machine to 4m / min, and drive the Mayer winding rod to evenly coat the flame retardant coating on the paper, with a coating amount of 3g / m 2 ; S4. After natural drying, a flame retardant coated paper with high temperature carbonization but no combustion is obtained. Example

[0025] Preparation of flame retardant coatings: S1. First, 1.5g polyacrylamide, 375g hydroxyapatite and 125g magnesium aluminum hydrotalcite were added to 205g water in sequence, and stirred at room temperature at a speed of 1980r / min by a high-speed disperser for use; S2, add 15g sodium carboxymethyl cellulose to 285g water, stir at room temperature under a low speed stirrer until completely dissolved and set aside; S3, add 80g of polyvinyl alcohol to 187g of water, heat to 60°C in a constant temperature water bath and stir at a low speed until transparent for later use; S4. The prepared mixed solution of 170g hydroxyapatite and magnesium aluminum hydrotalcite, 210g water, 30g prepared sodium carboxymethyl cellulose solution, 44g prepared polyvinyl alcohol, 12g hydroxylated styrene butadiene latex, 1g oleic acid, 2g modified glyoxal resin, and 0.1g polydimethylsiloxane are sequentially added into a high-speed shearing machine and sheared and dispersed at a speed of 1200r / min to finally obtain a uniformly mixed flame retardant coating.

[0026] Preparation of flame retardant coated paper: S1. Lay the base paper flat and fix it on the panel of the semi-automatic coating machine, and coat it; S2, first evenly distribute the prepared flame retardant coating on the paper base 1 cm away from the front end of the Meyer winding rod; S3, set the speed of the coating machine to 4m / min, and drive the Mayer winding rod to evenly coat the flame retardant coating on the paper, with a coating amount of 3g / m 2 ; S4. After natural drying, a flame retardant coated paper with high temperature carbonization but no combustion is obtained. Example

[0027] Preparation of flame retardant coatings: S1, first add 1.5g polyacrylamide, 333g hydroxyapatite, 111g magnesium aluminum hydrotalcite and 56g microporous calcium silicate into 205g water in sequence, stir evenly at room temperature at a speed of 1980r / min using a high-speed disperser, and set aside; S2, add 15g sodium carboxymethyl cellulose to 285g water, stir at room temperature under a low speed stirrer until completely dissolved and set aside; S3, add 80g of polyvinyl alcohol to 187g of water, heat to 60°C in a constant temperature water bath and stir at a low speed until transparent for later use; S4, the prepared 170g hydroxyapatite and magnesium aluminum hydrotalcite and microporous calcium silicate mixed solution, 210g water, prepared 30g sodium carboxymethyl cellulose solution, prepared 44g polyvinyl alcohol, 12g hydroxylated styrene butadiene latex, 1g oleic acid, 2g modified glyoxal resin, 0.1g polydimethylsiloxane were added to a high-speed shearing machine in sequence and sheared and dispersed at a speed of 1200r / min to finally obtain a uniformly mixed flame retardant coating.

[0028] Preparation of flame retardant coated paper: S1. Lay the base paper flat and fix it on the panel of the semi-automatic coating machine, and coat it; S2, first evenly distribute the prepared flame retardant coating on the paper base 1 cm away from the front end of the Meyer winding rod; S3, set the speed of the coating machine to 4m / min, and drive the Mayer winding rod to evenly coat the flame retardant coating on the paper, with a coating amount of 3g / m 2 ; S4. After natural drying, a flame retardant coated paper with high temperature carbonization but no combustion is obtained.

[0029] The flame retardant coatings prepared in the above Examples 1-4 were subjected to viscosity testing using a rotational viscometer method in accordance with GB / T9269-1988.

[0030] Table 1 Viscosity of prepared flame retardant coatings

[0031] The flame retardancy test of the tipping paper samples prepared in the above Examples 1-4 is as follows: (1) Flame retardant test conditions: In an environment with an air flow rate of 60 to 140 mm / s, a heating element with a temperature of 550 to 590°C and a diameter of 9 mm is used to penetrate the paper sample to be tested and stay for 3 seconds before leaving.

[0032] (2) Criteria for judging flame retardant performance: burning diameter of paper after extinguishing - heating element diameter. The smaller the value, the better the flame retardant performance.

[0033] The flame retardant performance test results of the above examples 1-4 are as follows Figure 1-4 As shown. Figure 4 It can be seen that the flame-retardant cork paper prepared in Example 4 has more excellent flame retardancy. The system composed of catalytic carbonized hydroxyapatite, heat-absorbing and diluted magnesium aluminum hydrotalcite and heat-insulating microporous calcium silicate pigment, after contacting the test element at a temperature of 550-590°C, the paper is quickly carbonized and does not burn at high temperature. At the same time, the carbonization circle does not spread, showing excellent high-efficiency flame retardancy, high-temperature carbonization, and non-burning performance.

[0034] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0035] In the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0036] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The term "comprise" or any other similar term is intended to cover a non-exclusive inclusion, such that a process, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, article, or apparatus / device.

[0038] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A flame retardant coating, characterized in that: The invention comprises the following raw materials in parts by weight: 80-85 parts of flame retardant pigment and 15-20 parts of heat-insulating pigment; the total weight of the above components is taken as a basis, and is designated as M. The adhesive is 8-15%M, the co-adhesive is 7-9%M, the thickener is 1-2%M, the lubricant is 0.6-1%M, the water repellent is 0.5-0.8%M, the defoamer is 0.1-0.2%M, and the dispersant is 0.2-0.3%M.

2. A flame retardant coating according to claim 1, characterized in that: The flame retardant pigment includes but is not limited to one or more mixtures of hydroxyapatite, aluminum hydroxide, magnesium hydroxide, wollastonite, hydrotalcite, kaolin, talc, sericite or zinc borate; The heat-insulating pigment includes, but is not limited to, one or more mixtures of calcined diatomaceous earth, microporous calcium silicate or expanded perlite powder; The adhesive includes but is not limited to one or more mixtures of carboxylated styrene butadiene latex, hydroxylated styrene butadiene latex or acrylate emulsion; The co-adhesive includes but is not limited to one of oxidized starch or polyvinyl alcohol or a mixture of the two; The thickener includes but is not limited to one of carboxymethyl cellulose or sodium carboxymethyl cellulose or a mixture of the two; The lubricant includes but is not limited to one or more mixtures of glyceryl stearate, polyoxyethylene ether or oleic acid; The water repellent includes but is not limited to one or more mixtures of polyamide polyurea water repellent, potassium zirconium carbonate type water repellent, modified glyoxal resin or starch water repellent; The defoaming agent includes but is not limited to one or more mixtures of emulsified silicone oil, polyoxypropylene glyceryl ether, polyoxypropylene polyoxyethylene glyceryl ether or polydimethylsiloxane; The dispersant includes, but is not limited to, one of polyacrylamide or starch modifier or a mixture of both.

3. A method for preparing a flame retardant coating according to claim 1, characterized in that: The following steps are involved: S1. Add dispersant, flame retardant pigment and heat-insulating pigment into water in order according to the proportion, stir evenly at room temperature with a high-speed disperser and set aside; S2, mixing the thickener and water according to the proportion, stirring at room temperature under a low-speed stirrer until completely dissolved and then set aside; S3, mixing the co-adhesive and water according to the proportion, heating in a constant temperature water bath and stirring at a low speed until the mixture becomes transparent and then set aside; S4. Add the flame retardant pigment solution, heat insulation pigment mixed solution, adhesive, co-adhesive solution, thickener solution, lubricant, water repellent, defoamer and water prepared above into a high-speed shearing machine in accordance with the proportion for shearing and dispersion, and finally obtain a uniformly mixed flame retardant coating.

4. The method for preparing a flame retardant coating according to claim 3, characterized in that: The viscosity of the flame retardant coating is 400-700cp.

5. An application of the flame retardant coating according to claim 1, characterized in that: The flame retardant coating is coated on the tipping paper by a surface coating method, comprising the following steps: S1. Lay the base paper flat and fix it on the panel of the semi-automatic coating machine; S2, evenly distributing the prepared flame retardant coating on the paper base 1 cm away from the front end of the Meyer winding rod; S3, setting the speed of the coating machine to 4m / min, and evenly coating the flame retardant coating on the paper driven by the Mayer winding rod; S4. After natural drying, a flame retardant coated paper with high temperature carbonization but no combustion is obtained.

6. The use of a flame retardant coating according to claim 5, characterized in that: The basis weight range of the tipping paper is 30-47 g / m 2 The water absorption Cobb60 of the smooth surface of the tipping paper is in the range of 20 to 35 g / m 2 .

7. The use of a flame retardant coating according to claim 5, characterized in that: When the flame retardant coating is applied to the tipping paper, the coating amount is 3-5 g / m 2 .

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