Top-coat-free thermo-sensitive paper suitable for high-speed printing and manufacturing method thereof

Abstract

The invention discloses top-coat-free thermo-sensitive paper suitable for high-speed printing and a manufacturing method of the top-coat-free thermo-sensitive paper, and belongs to the technical field of curtain type coating thermo-sensitive coating materials and processes. The top-coat-free thermo-sensitive paper is sequentially composed of a base material, a bottom coating and a top coating, the coating dry weight of the bottom coating is 4.2 + / -0.2 g / m, and the bottom coating comprises inorganic dye dispersion liquid, hollow balls, resin emulsion and the like; the coating dry weight of the surface coating is 3.3 + / -0.2 g / m, the surface coating comprises a color developing agent, an inorganic dye dispersion liquid, PVA, an inorganic dye grinding liquid and the like, the particle size D (4, 3) of the bisphenol A color developing agent is less than or equal to 0.50 mu m, and the particle size D (4, 3) of a silicon dioxide grinding dye is less than or equal to 0.60 mu m. The manufacturing method comprises the steps of preparation of coating liquid of each coating, curtain type coating, hot air drying and the like. By optimizing the formula and process of the coating, the lubricity of the top-coat-free thermo-sensitive paper is improved, precipitation and accumulation of a color developing agent are reduced, the problems of paper jam, printing head abrasion, image instability and the like in high-speed printing are solved, and the top-coat-free thermo-sensitive paper has the advantages of economic benefits and environmental protection and is suitable for large-scale application in high-speed printing scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of curtain coating heat-sensitive coating materials and processes, in particular to a top-coat-free heat-sensitive paper suitable for high-speed printing and a manufacturing method thereof. BACKGROUND

[0002] In recent years, the market demand for new heat-sensitive paper products has been growing, and higher requirements have been put forward for product quality stability, cost control and environmental performance. Traditional heat-sensitive paper usually adopts a multi-layer structure of "top coating layer + heat-sensitive layer + bottom coating layer + base material". Although the top coating layer can improve the weather resistance and wear resistance of the heat-sensitive paper and protect the print head, it significantly increases the production cost, and more coating layers mean more raw material consumption and environmental burden, which does not meet the current environmental trend.

[0003] Top-coat-free heat-sensitive paper has the advantages of low cost and outstanding environmental performance due to the omission of the top coating layer, and has gradually attracted industry attention, but it has exposed many significant defects in high-speed printing environment. Since the heat-sensitive coating layer directly contacts the print head, the lubricity in the layer is insufficient, and the commonly used color developing agent (such as bisphenol A) is easy to gradually precipitate and accumulate on the print head during continuous printing, resulting in high paper jam rate, severe print head wear, poor print image stability (such as blurred mottling, uneven density), and other problems during printing, which seriously restricts the large-scale application of top-coat-free heat-sensitive paper in high-speed printing scenarios.

[0004] Therefore, developing a top-coat-free heat-sensitive paper with excellent printing performance, low print head wear and high image stability and a manufacturing method thereof has become the key to solving the pain points of the prior art. SUMMARY

[0005] In view of the problems of insufficient lubricity, color developing agent precipitation and accumulation, high paper jam rate, severe print head wear, and poor image stability of existing top-coat-free heat-sensitive paper in high-speed printing, the present application provides a top-coat-free heat-sensitive paper suitable for high-speed printing and a manufacturing method thereof, aiming to improve the continuous printing performance of top-coat-free heat-sensitive paper, reduce paper jam and print head wear, ensure clear and stable print images, control production cost, and enhance product environmental advantages.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A top-coat-free heat-sensitive paper suitable for high-speed printing, characterized in that it is composed of a base material, a bottom coating layer and a surface coating layer in sequence, and the components and parameters of each coating layer are as follows:

[0008] The base coating comprises, by weight: 60.0-80.0% inorganic dye dispersion, 20.0-30.0% hollow spheres, 10.0-20.0% resin emulsion, 1.0-3.0% calcium stearate lubricant, 0.5-1.5% water-retaining agent, and 0.01-0.05% fatty acid ester defoamer;

[0009] The surface coating comprises, by weight: 30.0-40.0% color developer, 15.0-25.0% inorganic dye dispersion, 10.0-20.0% PVA, 5.0-15.0% inorganic dye grinding slurry, 5.0-10.0% sensitizer, 5.0-15.0% resin emulsion, 7.0-10.0% zinc stearate lubricant, 1.0-3.0% paraffin lubricant, 0.5-1.5% wetting agent, and 0.01-0.05% fatty acid ester defoamer;

[0010] As a preferred technical solution, the resin emulsions in the base coating and the top coating are each independently composed of any one or more of acrylic resin, styrene-butadiene resin, modified starch, and starch.

[0011] As a preferred technical solution, a method for manufacturing top-coated thermal paper suitable for high-speed printing includes the following steps:

[0012] S1. Substrate selection: Use base paper as the coating substrate;

[0013] S2. Preparation of inorganic dye dispersion: Water and inorganic dispersant are added to a grinding and dispersing tank. Inorganic dye is added at 800 rpm. After the addition is completed, the dispersion is carried out at 1200 rpm for 60 min. The solid content is tested to obtain the inorganic dye dispersion for later use.

[0014] S3. Preparation of the base coating liquid: Water is added to the preparation tank, and the inorganic dye dispersion and hollow spheres obtained in step S1 are added under stirring. Stir at 1200 rpm for 20 min, then calcium stearate lubricant, resin emulsion, water-retaining agent and fatty acid ester defoamer are added. After stirring at 1200 rpm for 20 min, the solid content of the coating is measured to form the base coating liquid for later use.

[0015] S4. Preparation of inorganic dye grinding slurry: Add water and inorganic dispersant to the grinding and dispersion tank.

[0016] PVA and inorganic dye powder were dispersed at 1200 rpm for 60 min, then pumped into a sand mill and ground three times until the particle size D(4,3) was controlled to be ≤0.60 μm. The powder was then poured into a clean container. After all grinding was completed, the solid content was tested to obtain the inorganic dye grinding liquid for later use.

[0017] S5. Preparation of topcoat coating liquid: Add water to the preparation tank, and add the inorganic dye dispersion obtained in step S1, the inorganic dye grinding liquid obtained in step S4 and the wetting agent in sequence while stirring. Stir at 1000 rpm for 30 min, and then add the color developer, sensitizer, PVA, resin emulsion, zinc stearate lubricant, paraffin lubricant and fatty acid ester defoamer in sequence. Stir at 1000 rpm for 54 min, and adjust the solid content to the preset value to obtain the topcoat coating liquid.

[0018] S6. Coating and Drying: The primer and topcoat are applied sequentially using a curtain coating method, and then the coating is dried with hot air and rolled up.

[0019] As a preferred technical solution, the inorganic dye dispersion in step S1 comprises, by weight, 98.0-99.0% inorganic dye and 1.0-2.0% inorganic dispersant.

[0020] As a preferred technical solution, the inorganic dye mentioned in step S1 is any one or a mixture of several of heavy calcium carbonate, light calcium carbonate, silicon dioxide, calcined kaolin, and washed kaolin, wherein the particle size distribution D(4,3) of silicon dioxide as a colorless dye is controlled to be ≤0.60μm.

[0021] As a preferred technical solution, the inorganic dye grinding liquid in step S4 is prepared from the following components By weight percentage, it includes: inorganic dyes: 90.0-95.0%, inorganic dispersant: 1.0-2.0%,

[0022] PVA: 3.0-6.0%.

[0023] As a preferred technical solution, the colorimetric agent in step S5 is bisphenol A, and its particle size distribution is D(4,3)≤0.50μm.

[0024] As a preferred technical solution, in step S6, the dry weights of the primer coating and the topcoat coating are respectively: primer coating dry weight 4.2 ± 0.2 g / m². 2 The dry weight of the topcoat is 3.3 ± 0.2 g / m². 2 .

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This invention significantly improves the continuous printing performance of top-coated thermal paper: by adding calcium stearate lubricant to the base coating and zinc stearate lubricant and paraffin lubricant to the top coating, the lubrication performance of the coating is optimized, reducing the friction between the coating and the print head during high-speed printing, reducing paper jam rate and print head wear, extending print head life and reducing end-user costs;

[0027] 2. This invention ensures clear and stable printed images: By strictly controlling the particle size distribution D(4,3)≤0.50μm of the developer (bisphenol A) and the particle size distribution D(4,3)≤0.60μm of the ground colorless dye (silica), and optimizing the coating formulation system, the precipitation and accumulation of the developer during continuous printing are reduced, avoiding problems such as image blurring, uneven concentration, etc., and ensuring the stability of the clarity of the barcode.

[0028] 3. This invention has both economic and environmental advantages: without affecting the appearance and basic performance of the paper, it eliminates the top coating of traditional thermal paper, while optimizing the formula ratio and preparation process of each coating, reducing the production cost of thermal coatings and enhancing the market competitiveness of the product; in addition, it reduces the consumption of coating raw materials, reduces environmental pressure, and conforms to the trend of green production. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example: This example provides a method for manufacturing top-coated thermal paper suitable for high-speed printing. The specific steps are as follows:

[0031] S1. Substrate selection: Conventional base paper is selected as the coating substrate;

[0032] S2. Preparation of inorganic dye dispersion: Add an appropriate amount of water and inorganic dispersant to a grinding and dispersing tank, start stirring, and slowly add inorganic dye at 800 rpm (the inorganic dye used in this step is heavy calcium carbonate powder). The weight ratio of inorganic dye is 98.5% and the weight ratio of inorganic dispersant is 1.5%. Then increase the speed to 1200 rpm and disperse at high speed for 60 minutes. Pour into a tank and test the solid content to obtain inorganic dye dispersion for later use.

[0033] S3. Preparation of the base coat coating liquid: Add water to the preparation tank, start stirring, and add the inorganic dye dispersion prepared in step S1 and hollow spheres in sequence. The weight ratio of the inorganic dye dispersion is 70.0% and the weight ratio of the hollow spheres is 25.0%. Set the speed to 1200 rpm and stir for 20 min. Then add calcium stearate lubricant 2.0%, acrylic resin emulsion 15.0%, water retention agent 1.0%, and fatty acid ester defoamer 0.03% in sequence. Continue stirring at 1200 rpm for 20 min. Measure the solid content of the coating to form the base coat coating liquid for later use.

[0034] S4. Preparation of Inorganic Dye Grinding Solution: Add an appropriate amount of water to a grinding and dispersion tank, and then add inorganic dispersant (1.5%), PVA (4.5%), and inorganic dye (94.0%) by weight (silica powder is used for inorganic dye in this step). Start stirring and disperse at high speed of 1200 rpm for 60 minutes. Pump the solution into a sand mill and grind it three times. The particle size D(4,3) = 0.55 μm (≤0.60 μm) is measured. Pour the solution into a clean bucket. After all grinding is completed, test the solid content to obtain the inorganic dye grinding solution for later use.

[0035] S5. Preparation of topcoat coating solution: Add a small amount of water to the preparation tank, start stirring, and add 20.0% inorganic dye dispersion obtained in step S1, 10.0% inorganic dye grinding slurry obtained in step S4, and 1.0% wetting agent in sequence according to the weight ratio. Stir at 1000 rpm for 30 min. Then add 35.0% color developer, 7.5% sensitizer, 15.0% PVA, 10.0% resin emulsion, 8.5% zinc stearate lubricant, 2.0% paraffin lubricant, and 0.03% fatty acid ester defoamer in sequence according to the weight ratio. Stir at 1000 rpm for 54 min. Adjust the solid content to the preset value to obtain the topcoat coating solution.

[0036] S6. Coating and Drying: The primer coating liquid and topcoat coating liquid are separately injected into the feed trough of the curtain coating machine, and the primer coating and topcoat coating are applied to the substrate in sequence. The dry weight of the primer coating is controlled at 4.2 g / m². 2 The dry weight of the topcoat is controlled at 3.3 g / m². 2 After each coating is applied, it is dried with hot air and then rolled up to obtain the finished product of thermal paper without top coating.

[0037] Table 1 shows the performance test results of the top-coated thermal paper prepared in the above embodiments.

[0038] Table 1

[0039]

[0040] In the above-mentioned performance test of the top-coated thermal paper: the top-coated thermal paper prepared in the above embodiment was continuously printed for 80 meters. During the printing process, there were no abnormal noises, scratches, or paper jams. The absence of abnormal accumulation of developer on the print head indicates that the developer in the top-coated thermal paper precipitates and accumulates less during continuous printing, avoiding problems such as image blurring, uneven density, etc., and ensuring the stability of the clarity of the barcode. The top-coated thermal paper has high smoothness, extends the life of the print head, and enhances image clarity and anti-friction performance.

[0041] In summary, this invention provides a top-coated-free thermal paper suitable for high-speed printing and its manufacturing method, significantly improving the continuous printing performance of the top-coated-free thermal paper: by adding calcium stearate lubricant to the base coating and combining zinc stearate lubricant and paraffin lubricant in the top coating, the lubrication performance of the coating is optimized, reducing friction between the coating and the print head during high-speed printing, reducing paper jam rate and print head wear, extending print head lifespan, and reducing end-user costs; this invention also ensures clear and stable printed images: by strictly controlling the particle size distribution D(4,3)≤0.50μm of the developer (bisphenol A) and grinding the colorless dye (carbon dioxide)... The particle size distribution of silicon (D(4,3)≤0.60μm) is optimized, and the coating formulation system is improved to reduce the precipitation and accumulation of color developer during continuous printing, avoiding problems such as image blurring, uneven concentration, etc., and ensuring the stability of the clarity of the barcode. This invention has both economic and environmental advantages: without affecting the appearance and basic performance of the paper, the top coating of traditional thermal paper is eliminated, and the formulation ratio and preparation process of each coating are optimized, reducing the production cost of thermal coating and improving the market competitiveness of the product. In addition, the consumption of coating raw materials is reduced, the environmental pressure is reduced, and it is in line with the trend of green production.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that various other embodiments can be derived from it without departing from the spirit or essential characteristics of the invention.

[0043] His specific form implements the invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

Claims

1. A top-coated thermal paper suitable for high-speed printing, characterized in that, It consists of a substrate, a primer, and a topcoat, and the composition and parameters of each coating are as follows: The base coating comprises, by weight: 60.0-80.0% inorganic dye dispersion, 20.0-30.0% hollow spheres, 10.0-20.0% resin emulsion, 1.0-3.0% calcium stearate lubricant, 0.5-1.5% water-retaining agent, and 0.01-0.05% fatty acid ester defoamer; The topcoat comprises, by weight: 30.0-40.0% color developer, 15.0-25.0% inorganic dye dispersion, 10.0-20.0% PVA, 5.0-15.0% inorganic dye polishing slurry, 5.0-10.0% sensitizer, 5.0-15.0% resin emulsion, 7.0-10.0% zinc stearate lubricant, 1.0-3.0% paraffin lubricant, 0.5-1.5% wetting agent, and 0.01-0.05% fatty acid ester defoamer.

2. The top-coated-free thermal paper adapted for high-speed printing according to claim 1, characterized in that, The resin emulsions in the base coating and top coating are each independently one or more of acrylic resin, styrene-butadiene resin, modified starch, and starch.

3. A method for manufacturing a top-coated thermal paper suitable for high-speed printing according to claims 1-2, characterized in that, Includes the following steps: S1. Substrate selection: Use base paper as the coating substrate; S2. Preparation of inorganic dye dispersion: Water and inorganic dispersant are added to a grinding and dispersing tank. Inorganic dye is added at 800 rpm. After the addition is completed, the mixture is dispersed at 1200 rpm for 60 min. The solid content is tested to obtain the inorganic dye dispersion for later use. S3. Preparation of the base coating liquid: Water is added to the preparation tank, and the inorganic dye dispersion and hollow spheres obtained in step S1 are added under stirring. Stir at 1200 rpm for 20 min, then calcium stearate lubricant, resin emulsion, water-retaining agent and fatty acid ester defoamer are added. After stirring at 1200 rpm for 20 min, the solid content of the coating is measured to form the base coating liquid for later use. S4. Preparation of inorganic dye grinding slurry: Add water, inorganic dispersant, PVA and inorganic dye powder to a grinding and dispersion tank, disperse at high speed of 1200 rpm for 60 min, pump into a sand mill and grind three times until the particle size D(4,3) is controlled at ≤0.60μm, pour into a clean bucket, test the solid content after all grinding is completed, and obtain inorganic dye grinding slurry for use. S5. Preparation of topcoat coating liquid: Add water to the preparation tank, and add the inorganic dye dispersion obtained in step S1, the inorganic dye grinding liquid obtained in step S4 and the wetting agent in sequence while stirring. Stir at 1000 rpm for 30 min, and then add the color developer, sensitizer, PVA, resin emulsion, zinc stearate lubricant, paraffin lubricant and fatty acid ester defoamer in sequence. Stir at 1000 rpm for 54 min, and adjust the solid content to the preset value to obtain the topcoat coating liquid. S6. Coating and Drying: The primer and topcoat are applied sequentially using a curtain coating method, and then the coating is dried with hot air and rolled up.

4. The method for manufacturing a top-coated thermal paper suitable for high-speed printing according to claim 3, characterized in that, The inorganic dye dispersion in step S1 comprises, by weight, 98.0-99.0% inorganic dye and 1.0-2.0% inorganic dispersant.

5. A method for manufacturing a top-coated thermal paper suitable for high-speed printing according to claim 4, characterized in that, The inorganic dye mentioned in step S1 is any one or a mixture of several of heavy calcium carbonate, light calcium carbonate, silica, calcined kaolin, and washed kaolin, wherein the particle size distribution D(4,3) of the silica colorless dye is controlled to be ≤0.60μm.

6. The method for manufacturing a top-coated thermal paper suitable for high-speed printing according to claim 3, characterized in that, The inorganic dye grinding slurry mentioned in step S4 comprises the following components in weight proportions: inorganic dye: 90.0-95.0%, inorganic dispersant: 1.0-2.0%, and PVA: 3.0-6.0%.

7. The method for manufacturing a top-coated thermal paper suitable for high-speed printing according to claim 3, characterized in that, The colorimetric agent mentioned in step S5 is bisphenol A, and its particle size distribution is D(4,3)≤0.50μm.

8. A method for manufacturing a top-coated thermal paper suitable for high-speed printing according to claim 3, characterized in that, In step S6, the dry weights of the primer and topcoat are 4.2 ± 0.2 g / m² for the primer and 3.3 ± 0.2 g / m² for the topcoat.

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