CN119266018A

CN119266018A - A high-efficiency production method for digital thermal transfer paper

Info

Publication number: CN119266018A
Application number: CN202411492930.3A
Authority: CN
Inventors: 张宴臣; 张海峡; 石忠收; 韩孝琴; 陈达志
Original assignee: Zhejiang Five Star Paper Co ltd
Current assignee: Wuzhou Special Paper Industry Jiangxi Co ltd
Priority date: 2024-10-24
Filing date: 2024-10-24
Publication date: 2025-01-07
Anticipated expiration: 2044-10-24
Also published as: CN119266018B

Abstract

The invention discloses a high-efficiency production method of digital heat transfer paper, which belongs to the technical field of papermaking, and comprises the steps of mixing modified starch with water and heating to form sizing liquid, respectively preparing surface sizing liquid and coating sizing liquid by mixing styrene-acrylic surface sizing agent with rosin gum, light calcium carbonate and sodium carboxymethyl cellulose, crushing, diluting and pulping the sizing liquid to form mixed sizing liquid with proper beating degree, adding wet strength agent in the sizing liquid and PPE into the mixed sizing liquid, screening and purifying the sizing liquid by a sizing pump, a sand remover and a pressure screen, then forming on a net, adding auxiliaries such as polyethyleneimine, calcium silicate and silica sol, and finally obtaining the digital heat transfer paper with excellent tensile strength and folding endurance after the paper sheet is subjected to squeezing, surface sizing and drying. Compared with the prior art, the method not only improves the production efficiency, but also ensures the printing quality and mechanical property of the digital thermal transfer paper, and meets the market demand of high-performance transfer paper.

Description

Efficient production method of digital thermal transfer paper

Technical Field

The invention relates to the technical field of papermaking, in particular to a high-efficiency production method of digital thermal transfer paper.

Background

With the rapid development of digital printing technology, digital thermal transfer paper is used as a special printing material, and the market demand of the digital thermal transfer paper is growing. Digital thermal transfer paper can transfer digital images to various printing objects such as clothing, ceramics, metal and the like through a thermal transfer technology, and is widely applied to personalized customized products. However, the conventional digital thermal transfer paper production method has some limitations such as low production efficiency, unstable paper performance, and substandard tensile strength and folding endurance.

The Chinese patent CN106758536A discloses a production method of light-coating digital heat transfer printing paper, which comprises the steps of preparing internal sizing liquid, preparing surface coating glue liquid, breaking sizing liquid, pulping, shaping on a net, surface sizing, coating and the like. The invention provides a production method of light-coating digital thermal transfer paper which has good ink compatibility, high drying speed, high transfer rate and no curl. However, the light-coated digital thermal transfer paper prepared by the method has poor tensile strength and folding endurance, and is limited to be used in certain application scenes.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a high-efficiency production method of digital thermal transfer paper, which improves the preparation process of sizing solution and coating solution by optimizing raw material selection, precisely controls key parameters in the production process so as to improve the quality and the production efficiency of paper and simultaneously ensures that the final product has good printability and mechanical properties.

In order to achieve the above object, the present invention adopts the following technical scheme:

The high-efficiency production method of the digital thermal transfer paper comprises the following steps of:

step 1, preparing an internal sizing solution, namely adding 3-5 parts of modified starch into 100-120 parts of water, uniformly stirring, heating to 90-100 ℃, and preserving heat for 10-30 minutes to prepare an internal sizing solution;

Step 2, preparing a surface sizing solution, namely adding 0.5-2 parts of styrene-acrylic surface sizing agent and 40-60 parts of rosin size into 250-350 parts of water, mixing, heating to 90-100 ℃, uniformly stirring, and preserving heat for 10-30 minutes to obtain a surface sizing solution;

step 3, preparing a coating glue solution, namely adding 0.5-2 parts of light calcium carbonate and 3-5 parts of sodium carboxymethylcellulose into 10-15 parts of water, and uniformly stirring to obtain the coating glue solution;

step 4, pulp crushing and pulping, namely crushing softwood pulp for 10-30 minutes, adding water for dilution, and pulping into mixed pulp;

Step 5, pulping, namely pumping the well-beaten mixed pulp into a batching pool, adding 5-10 parts of the in-pulp sizing liquid prepared in the step 1 with the ton paper dosage and 15-18 parts of the PPE wet strength agent with the ton paper dosage into the batching pool, and uniformly mixing;

Step 6, net surfing and molding, namely preparing the slurry in the step 5 into slurry with the concentration of 0.7% -0.9%, screening, purifying and net surfing and molding through a slurry pump, a sand remover and a pressure screen, adding 0.1% -0.3 part of polyethylenimine with the dosage of ton paper and 35% -45 parts of calcium silicate with the dosage of ton paper into an inlet of the slurry pump, adding 2% -4 parts of silica sol with the dosage of ton paper into a low-concentration slurry stabilizing box, adding 5% -10 parts of GBS-02 papermaking surface sizing agent with the dosage of ton paper into an outlet pipe of the low-concentration slurry stabilizing box, and preparing paper through net surfing, molding, dewatering and drying;

step 7, sizing and drying, namely carrying out surface sizing on the dried base paper, wherein the sizing amount of the surface sizing solution prepared in the step 2 is 1-3 g/m ², the surface sizing solution is coated on the front surface of the paper, the sizing amount of the coating solution prepared in the step 3 is 1-2 g/m ², the coating solution is coated on the back surface of the paper, the coated paper is pre-dried in a non-contact hot air drying box, and then is finally dried in a post-drying part, and the water content of the finally dried paper is 3-5%;

and 8, rewinding, namely, the end face of the rewinding is neat, the paper surface is smooth, and finally, packaging is carried out to obtain a finished product.

And (3) adding water to dilute the slurry to the concentration of 3.5-4.5% by weight in the step (4).

And (3) beating the mixed slurry in the step (4) to obtain the mixed slurry with the beating degree of 25-27 ⁰ SR.

And (5) diluting the PPE wet strength agent stock solution of the PPE wet strength agent in the step (5) by 8-12 times of water.

The pressing part in the step 6 is composed of four-roller three-pressing areas, the pressure of the three-pressing areas is 45-55 kN/m ²、65～75kN/m²、105～115kN/m², the dryness of the pressed wet paper sheet is 40-48%, and the water content of the dried paper sheet is 3-5%.

In the step 8, the rewinding speed is controlled to be 200-400 m/min, the quantitative control is controlled to be 70-90 g/m ², and the moisture is controlled to be 4-5%.

The preparation method of the modified starch comprises the following steps of:

S1, adding 4-6 parts of mixed starch into water, regulating the water content to 25-35%, uniformly mixing in a high-speed stirrer at 70-90 ℃ to obtain gelatinized starch, adding 0.5-0.7 part of sorbitol, 0.3-0.5 part of N, N-di (2, 3-epoxypropyl) isopropylamine and 0.005-0.02 part of sodium persulfate into the gelatinized starch, heating and stirring to control the temperature to 60-80 ℃ and the stirring time to 1-3 hours, and dripping 2-5 mol/L of diluted hydrochloric acid to regulate the pH value to 7-8 to obtain a mixture;

S2, placing the mixture prepared in the step S1 into a double-screw extruder for extrusion, setting the rotating speed of the screw to be 200-400 rpm, injecting 0.04-0.06 part of methylglyoxal into a fifth section of cylinder of the extruder by using a liquid spray gun, placing the extruded mixture into a gamma-ray radiation field for radiation irradiation, wherein the radiation dose is 6-10 kGy and the irradiation time is 3-5 hours, placing the irradiated mixture into an oven for drying for 3-8 hours, setting the temperature of the oven to be 60-80 ℃, cooling at room temperature, and grinding by using a ball mill to obtain modified starch through a 200-400 mesh sieve.

The mixed starch is equal mass mixture of tapioca starch, corn starch and potato starch.

The temperature gradient of the twin-screw extruder is set to 65-75 ℃, 85-95 ℃, 105-115 ℃, 115-125 ℃, 125-135 ℃ and 135-145 ℃.

In the efficient production method of the digital thermal transfer paper, the functions of all substances are as follows:

the modified starch is used as the main component of the sizing liquid in the pulp, so that the cohesion and sizing effect of the paper are enhanced, and the strength and water resistance of the paper are improved.

The styrene-acrylic surface sizing agent is mixed with rosin size for surface sizing, so that the surface strength and printability of paper are improved.

Rosin size is mixed with styrene-acrylic surface sizing agent for surface sizing to increase water resistance and printing adaptability of paper.

The light calcium carbonate is used as a filler of the coating glue solution to improve the smoothness and whiteness of the paper.

Sodium carboxymethyl cellulose is used as an adhesive for coating glue solution, so that the adhesive force of the paint and the coating performance of paper are enhanced.

Softwood pulp is used as the primary raw material for paper making and provides the basic strength and structure of paper.

The PPE wet strength agent enhances the strength of paper in a wet state and improves the toughness and the service performance of the paper.

The polyethyleneimine is used as a retention aid, so that the retention rate of the filler and the fiber in the paper is improved, and the strength of the paper is improved.

Calcium silicate is used as a filler to improve the smoothness and printability of the paper.

The silica sol is used as an auxiliary agent to improve the coating performance of the paper and the strength of the paper.

The GBS-02 papermaking surface sizing agent further enhances the surface sizing effect of paper, and improves the water resistance and printability of the paper.

And pyruvaldehyde is used as a cross-linking agent, so that the cross-linking density of the modified starch is enhanced, and the mechanical strength and folding resistance of the paper are improved.

Sorbitol acts as a plasticizer to increase the plasticity of the starch, making it easier to process and modify.

N, N-di (2, 3-epoxypropyl) isopropyl amine is used as a cationic etherifying agent, so that cationic groups are introduced into the molecular chain of starch, and the binding force between the starch and fibers is enhanced.

Sodium persulfate is used as an initiator to promote the etherification reaction of starch.

The diluted hydrochloric acid is used for adjusting the pH value, so that the smooth progress of the reaction is ensured.

The gamma-ray radiation field is used for the radiation treatment of modified starch, and the performance of the modified starch is further improved.

The combination and interaction of the substances can lead the invention to produce high-quality digital thermal transfer paper with good printability and mechanical properties.

Compared with the prior art, the method has the following beneficial effects:

1) According to the invention, the preparation of the modified starch is combined with the production process of the digital thermal transfer paper, so that the integrated production is realized, and two processing steps of raw paper production and coating processing are reduced, thereby improving the production efficiency.

2) The use of the modified starch of the invention improves the cohesive force and sizing effect of paper, and simultaneously improves the surface property and printability of the paper by precisely controlling the preparation and application of sizing solution and coating solution, so that the final product has better tensile strength and folding endurance.

Detailed Description

The main material sources are as follows:

The styrene-acrylic surface sizing agent is MX-611, ming Xiang chemical technology (Shandong) group Co.

Rosin size, product number is HY-500665, shandong Haohao New Material Co.

Light calcium carbonate with 3000 mesh.

PPE wet strength agent stock solution, product number JR-1001, jia run chemical Co., taian City.

Polyethylenimine CAS 9002-98-6, cat# 20240806, wuhan Ji Xinyi, bunge Biotech Co.

The mesh number of the calcium silicate is 2000 mesh.

Silica sol, cat No. 0450422, shandong Usoxhlet chemical engineering Co.

GBS-02 papermaking surface sizing agent, namely GBS-02, guangzhou Tung chemical engineering Co., ltd.

The other raw materials in the examples and comparative examples of the present invention are all commercially available products.

The design idea of the invention is to optimize the production process of the digital thermal transfer paper, and improve the quality and the production efficiency of the paper by precisely controlling the selection and the treatment steps of raw materials and the preparation of sizing solution and coating solution. Specifically, the cohesive force and the sizing effect of the paper are enhanced by using modified starch, the surface performance of the paper is improved by combining a styrene-acrylic surface sizing agent and rosin size, and the uniformity of a coating glue solution and the printability of the paper are improved by using sodium carboxymethyl cellulose and light calcium carbonate. Meanwhile, the required dryness and moisture content of the paper are ensured by finely controlling the processes of slurry treatment, net forming, squeezing dehydration and drying. In addition, the gamma-ray radiation field is adopted to radiate the mixture, and methylglyoxal is injected into the preparation of the modified starch as a cross-linking agent in the extrusion process, so that the cross-linking density of the modified starch and the mechanical strength of paper are further improved. Finally, the finished product with the quantitative, moisture and surface flatness meeting the standards is obtained through rewinding and packaging steps. The design thought aims at improving the product performance through technical innovation and meeting the requirement of efficient production.

Example 1

The high-efficiency production method of the digital heat transfer paper comprises the following steps:

Step 1, preparing an internal sizing solution, namely adding 4kg of modified starch into 110kg of water, uniformly stirring, heating to 95 ℃, and preserving heat for 20 minutes to prepare an internal sizing solution;

step 2, preparing a surface sizing liquid, namely adding 1kg of styrene-acrylic surface sizing agent and 50kg of rosin size into 300kg of water, mixing, heating to 95 ℃, uniformly stirring, and preserving heat for 20 minutes to obtain a surface sizing liquid;

Step 3, preparing coating glue solution, namely adding 1kg of light calcium carbonate and 4kg of sodium carboxymethyl cellulose into 12kg of water, and uniformly stirring to obtain the coating glue solution;

Step 4, pulp crushing and pulping, namely crushing softwood pulp for 20 minutes, adding water to dilute the softwood pulp to pulp with the weight concentration of 4%, and beating the pulp to obtain mixed pulp with the beating degree of 26 ⁰ SR;

Step 5, pulping, namely pumping the well-beaten mixed pulp into a batching pool, adding 8kg of the pulp internal sizing liquid prepared in the step 1 into the batching pool, and adding 16kg of PPE wet strength agent into the batching pool, and uniformly mixing, wherein the PPE wet strength agent is obtained by diluting the PPE wet strength agent stock solution with 10 times of water;

Step 6, net surfing molding, namely preparing the slurry in the step 5 into 0.8% concentration, screening and purifying the slurry through a slurry pump, a sand remover and a pressure screen, net surfing molding, adding 0.2kg of polyethyleneimine and 40kg of calcium silicate with per ton of paper into an inlet of the slurry pump, adding 3kg of silica sol with per ton of paper into a low-concentration slurry stabilizing box, adding 8kg of GBS-02 papermaking surface sizing agent with per ton of paper into an outlet pipe of the low-concentration slurry stabilizing box, and performing net surfing molding, squeezing and drying to obtain paper sheets, wherein a squeezing part in the squeezing and dewatering consists of four-roller three-pressure areas, the pressures of the three-pressure areas are respectively 50kN/m ²、70kN/m²、110kN/m², the dryness of the wet paper sheets after squeezing is 45%, and the water content of the paper sheets after drying is 5%;

Step 7, sizing and drying, namely carrying out surface sizing on the dried base paper, wherein the sizing amount of the surface sizing solution prepared in the step 2 is 2g/m ² and is coated on the front surface of the paper, the sizing amount of the coating sizing solution prepared in the step 3 is 1.5g/m ² and is coated on the back surface of the paper, and the coated paper is pre-dried in a non-contact hot air drying box and finally dried in a post-drying part, wherein the water content of the finally dried paper is 4%;

And 8, rewinding and packaging, wherein the speed of rewinding is controlled at 300m/min, the quantitative control is controlled at 80g/m ², the moisture is controlled at 4.1%, the end face of rewinding is neat, the paper surface is smooth, and finally the finished product is obtained by packaging.

The preparation method of the modified starch comprises the following steps:

S1, adding 5kg of mixed starch into water, regulating the water content to 30%, uniformly mixing in a high-speed stirrer at 80 ℃ to obtain gelatinized starch, adding 0.6kg of sorbitol, 0.4kg of N, N-di (2, 3-epoxypropyl) isopropylamine and 0.01kg of sodium persulfate into the gelatinized starch, heating and stirring to control the temperature to 70 ℃, stirring for 1.5 hours, and dripping 4mol/L dilute hydrochloric acid to regulate the pH value to 7 to obtain a mixture;

s2, extruding the mixture prepared in the step S1 in a double-screw extruder, setting the rotating speed of the screw to 300rpm, setting the temperature gradient of the double-screw extruder to 70 ℃,90 ℃,110 ℃,120 ℃,130 ℃ and 140 ℃, injecting 0.05kg of methylglyoxal into a fifth section of cylinder of the double-screw extruder by using a liquid spray gun, putting the extruded mixture in a gamma-ray radiation field for radiation, wherein the radiation dose is 8kGy and the radiation time is 4 hours, putting the irradiated mixture in an oven for drying for 5 hours, setting the temperature of the oven to 70 ℃, then cooling at room temperature, and grinding by using a ball mill and sieving with a 300-mesh sieve to obtain modified starch.

Example 2

The efficient production method of the digital thermal transfer paper is basically the same as that of the example 1, and the only difference is that the preparation method of the modified starch is different.

The preparation method of the modified starch comprises the following steps:

S1, adding 5kg of mixed starch into water, regulating the water content to 30%, uniformly mixing in a high-speed stirrer at 80 ℃ to obtain gelatinized starch, adding 0.6kg of sorbitol, 0.4kg of bis (2-methylpropyl) [ (ethylene oxide-2-yl) methyl ] amine and 0.01kg of sodium persulfate into the gelatinized starch, heating and stirring to control the temperature to 70 ℃ and the stirring time to 1.5 hours, and dripping 4mol/L of diluted hydrochloric acid to regulate the pH value to 7 to obtain a mixture;

The mixed starch was the same as in example 1.

Example 3

The preparation method of the modified starch comprises the following steps:

S1, adding 5kg of mixed starch into water, regulating the water content to 30%, uniformly mixing in a high-speed stirrer at 80 ℃ to obtain gelatinized starch, adding 0.6kg of sorbitol, 0.4kg of (2, 3-epoxypropyl) [2- (methacryloyloxy) ethyl ] dimethyl ammonium chloride and 0.01kg of sodium persulfate into the gelatinized starch, heating and stirring to control the temperature to 70 ℃ and the stirring time to 1.5 hours, and dripping 4mol/L of diluted hydrochloric acid to regulate the pH value to 7 to obtain a mixture;

The mixed starch was the same as in example 1.

Example 4

The preparation method of the modified starch comprises the following steps:

S1, adding 5kg of mixed starch into water, regulating the water content to 30%, uniformly mixing in a high-speed stirrer at 80 ℃ to obtain gelatinized starch, adding 0.6kg of sorbitol, 0.4kg of 2, 3-epoxypropyl trimethyl ammonium chloride and 0.01kg of sodium persulfate into the gelatinized starch, heating and stirring to control the temperature to 70 ℃ and the stirring time to 1.5 hours, and dripping 4mol/L of diluted hydrochloric acid to regulate the pH value to 7 to obtain a mixture;

The mixed starch was the same as in example 1.

Example 5

The preparation method of the modified starch comprises the following steps:

S2, placing the mixture prepared in the step S1 into a double-screw extruder for extrusion, setting the rotating speed of the screw to 300rpm, setting the temperature gradient of the double-screw extruder to 70 ℃,90 ℃,110 ℃,120 ℃,130 ℃ and 140 ℃, injecting 0.05kg of sodium hexametaphosphate into a fifth section of cylinder of the double-screw extruder by using a liquid spray gun, placing the extruded mixture into a gamma-ray radiation field for radiation, wherein the radiation dose is 8kGy and the radiation time is 4 hours, placing the irradiated mixture into an oven for drying for 5 hours, setting the temperature of the oven to 70 ℃, then cooling at room temperature, and grinding by using a ball mill to obtain modified starch through a 300-mesh sieve.

The mixed starch was the same as in example 1.

Example 6

The preparation method of the modified starch comprises the following steps:

S2, extruding the mixture prepared in the step S1 in a double-screw extruder, setting the rotating speed of the screw to 300rpm, setting the temperature gradient of the double-screw extruder to 70 ℃,90 ℃,110 ℃,120 ℃,130 ℃ and 140 ℃, injecting 0.05kg glyoxal into a fifth barrel of the double-screw extruder by a liquid spray gun, putting the extruded mixture in a gamma-ray radiation field for radiation irradiation, wherein the radiation dose is 8kGy and the irradiation time is 4 hours, putting the irradiated mixture in an oven for drying for 5 hours, setting the temperature of the oven to 70 ℃, then cooling at room temperature, and grinding by using a ball mill and sieving with a 300-mesh sieve to obtain modified starch.

The mixed starch was the same as in example 1.

Comparative example 1

Step 1, preparing an internal sizing solution, namely adding 4kg of mixed starch into 110kg of water, uniformly stirring, heating to 95 ℃, and preserving heat for 20 minutes to prepare the internal sizing solution;

Test example 1

The tensile strength (KN/m) was measured according to GB/T12914-2018 standard for constant speed tensile method (20 mm/min) for determination of tensile Strength of paper and paperboard.

The test results are shown in Table 1.

TABLE 1

Test example 2

Folding endurance test the folding endurance tester (Jinan Sanquan Zhongshi laboratory instruments Co., ltd.) of the paper, and the test parameters are that the paper cut into 5cm multiplied by 1cm is folded back and forth at room temperature until the paper breaks.

The test results are shown in Table 2.

TABLE 2

As can be seen from the data of tables 1 and 2, the digital thermal transfer paper prepared in example 1 has better tensile strength and folding endurance.

N, N-di (2, 3-epoxypropyl) isopropylamine is used as a cationic etherifying agent, and plays a key role in the preparation process of modified starch. The molecular structure of the compound contains two epoxy groups, and can react with hydroxyl groups in starch molecules to form stable ether bonds. This reaction not only enhances the cationic character of the starch, but also enhances its adhesion and dispersibility during paper sizing. The action mechanism of N, N-di (2, 3-epoxypropyl) isopropylamine is mainly that the epoxy group of the N, N-di (2, 3-epoxypropyl) isopropylamine and the hydroxyl of starch molecules are subjected to ring-opening reaction, and a cationic group is introduced, so that modified starch is obtained. The existence of isopropylamine groups in the molecular structure ensures that the compound has better hydrophilicity and reactivity, can form a stronger cross-linked network among starch molecules, and improves the mechanical stability and water resistance of starch. In contrast, the cross-linking agents used in other examples may not provide the same degree of cross-linking effect due to the difference in molecular structure, thus resulting in a difference in properties of the final product.

In example 1, methylglyoxal (Methylglyoxal), having the formula C ₃H₄O₂, contains a methyl group and a carbonyl group and an aldehyde group, wherein the carbonyl group is attached to the methyl group. In the paper modifying process, active aldehyde groups of methylglyoxal can undergo nucleophilic addition reaction with hydroxyl groups in cellulose molecules to form Schiff base, so that intermolecular crosslinking is enhanced through polymerization reaction, and the tensile strength and folding endurance of paper are improved. The presence of methylglyoxal provides hydrophobicity which helps to form a stable cross-linked network on the cellulosic fibers, thereby improving the mechanical properties of the paper. In contrast, sodium hexametaphosphate is commonly used as a chelating agent and a pH adjustor, and although it may also be used as a crosslinking agent, its crosslinking ability and reactivity may not be as active and effective as an organic crosslinking agent. Glyoxal, although also having two aldehyde groups, is smaller in molecule and does not contain hydrophobic groups, and may not provide multi-point crosslinking and stability like methylglyoxal. Thus, in paper modification, methylglyoxal exhibits more excellent properties due to its unique molecular structure and reaction characteristics.

Claims

1. A method for efficiently producing digital thermal transfer paper, characterized in that the method is as follows, in parts by weight:

Step 1, preparation of slurry sizing solution: add 3-5 parts of modified starch to 100-120 parts of water, stir evenly, heat to 90-100° C., keep warm for 10-30 minutes, and prepare slurry sizing solution;

Step 2, preparation of surface sizing solution: adding 0.5-2 parts of styrene acrylic surface sizing agent and 40-60 parts of rosin glue to 250-350 parts of water, mixing, heating to 90-100° C., stirring evenly, and keeping warm for 10-30 minutes to obtain surface sizing solution;

Step 3, preparation of coating glue: adding 0.5-2 parts of light calcium carbonate and 3-5 parts of sodium carboxymethyl cellulose to 10-15 parts of water and stirring evenly to obtain coating glue;

Step 4, pulp crushing and beating: crush the softwood pulp for 10 to 30 minutes, then dilute with water to form a mixed pulp;

Step 5, slurry preparation: pump the mixed slurry into a batching tank, add 5-10 parts of the sizing solution prepared in step 1 per ton of paper and 15-18 parts of the PPE wet strength agent per ton of pulp into the batching tank and mix them evenly;

Step 6, forming on the screen: after the slurry in step 5 is prepared to a concentration of 0.7% to 0.9%, it is screened and purified by a slurry pump, a sand remover, and a pressure screen, and then formed on the screen; 0.1 to 0.3 parts of polyethyleneimine per ton of paper and 35 to 45 parts of calcium silicate per ton of paper are added to the inlet of the slurry pump; 2 to 4 parts of silica sol per ton of paper are added to the low-concentration stabilizing box; 5 to 10 parts of GBS-02 papermaking surface sizing agent per ton of paper are added to the outlet pipe of the low-concentration stabilizing box; the paper sheets are obtained by forming on the screen, squeezing, dehydrating, and drying;

Step 7, sizing and drying: Surface sizing is performed on the dried base paper. The surface sizing liquid prepared in step 2 has a sizing amount of 1-3 g/m ² and is applied to the front side of the paper sheet. The coating sizing liquid prepared in step 3 has a sizing amount of 1-2 g/m ² and is applied to the back side of the paper sheet. The coated paper sheet first enters a non-contact hot air drying oven for pre-drying, and then enters a post-drying section for final drying. The moisture content of the dried paper sheet is 3-5%.

Step 8, rewinding and packaging: rewinding, the end surface of the rewinding is neat, the paper surface is flat, and finally packaging is performed to obtain the finished product.

2. The efficient production method of digital thermal transfer paper according to claim 1, characterized in that water is added in step 4 to dilute the slurry to a weight concentration of 3.5-4.5%.

3. The high-efficiency production method of digital thermal transfer paper according to claim 1, characterized in that the mixed slurry in step 4 is a mixed slurry with a beating degree of ^25-270 SR.

4. The efficient production method of digital thermal transfer paper according to claim 1, characterized in that the PPE wet strength agent in step 5 is obtained by diluting the PPE wet strength agent stock solution by 8 to 12 times with water.

5. The high-efficiency production method of digital thermal transfer paper according to claim 1, characterized in that the pressing section in the pressing and dehydration in step 6 is composed of four rollers and three pressing zones, and the pressures of the three pressing zones are respectively: 45-55kN/ ^m2 , 65-75kN/ ^m2 , and 105-115kN/ ^m2 ; the dryness of the wet paper sheet after pressing is 40-48%, and the moisture content of the dried paper sheet is 3-5%.

6. The high-efficiency production method of digital thermal transfer paper according to claim 1, characterized in that in step 8, the rewinding speed is controlled at 200-400 m/min, the basis weight is controlled at 70-90 g/ ^m2 , and the moisture content is controlled at 4-5%.

7. The high-efficiency production method of digital thermal transfer paper according to claim 1, characterized in that the preparation method of the modified starch is as follows, in parts by weight:

S1. Add 4 to 6 parts of mixed starch into water, adjust the water content to 25 to 35%, and mix them evenly in a high-speed mixer at 70 to 90° C. to obtain gelatinized starch; add 0.5 to 0.7 parts of sorbitol, 0.3 to 0.5 parts of N, N-di(2,3-epoxypropyl)isopropylamine, and 0.005 to 0.02 parts of sodium persulfate into the gelatinized starch, heat and stir to control the temperature at 60 to 80° C., and stir for 1 to 3 hours; add 2 to 5 mol/L of dilute hydrochloric acid dropwise to adjust the pH value to 7 to 8 to obtain a mixture;

S2, putting the mixed material prepared in step S1 into a twin-screw extruder for extrusion, and setting the screw speed to 200-400rpm; injecting 0.04-0.06 parts of methylglyoxal into the fifth barrel of the extruder with a liquid spray gun; putting the extruded mixed material into a γ-ray radiation field for radiation irradiation, with an irradiation dose of 6-10 kGy and an irradiation time of 3-5 hours; putting the irradiated mixed material into an oven for drying for 3-8 hours, and setting the oven temperature to 60-80°C; then cooling at room temperature; grinding the mixed material with a ball mill and passing it through a 200-400 mesh sieve to obtain modified starch.

8. The efficient production method of digital thermal transfer paper as described in claim 7 is characterized in that the mixed starch is a mixture of cassava starch, corn starch and potato starch in equal quantities.

9. The efficient production method of digital thermal transfer paper as described in claim 7 is characterized in that the temperature gradient of the twin-screw extruder is set to 65-75°C, 85-95°C, 105-115°C, 115-125°C, 125-135°C, 135-145°C.

10. A digital thermal transfer paper, characterized in that it is prepared by the production method according to any one of claims 1 to 9.