Environment-friendly phenol-free thermo-sensitive paper label material and preparation method thereof

Abstract

The invention discloses an environment-friendly phenol-free thermo-sensitive paper label material and a preparation method thereof, and relates to the technical field of thermo-sensitive paper. When the environment-friendly phenol-free thermo-sensitive paper label material is prepared, cellulose sequentially reacts with cyanoacetic acid, 4-(2-chloroethyoxyl) benzophenone and N, N-dimethylpropyl-1-amine to prepare modified cellulose; the preparation method comprises the following steps: carrying out reaction on silicon dioxide and diethylenetriamine propyl trimethoxy silane to prepare pre-modified silicon dioxide; reacting the pre-modified silicon dioxide, phosphorous acid and formaldehyde to obtain modified silicon dioxide; uniformly mixing functional styrene-butadiene emulsion, modified cellulose, modified silicon dioxide, a color developing agent, a lubricating agent, a sensitizer and colorless pigment to prepare a thermosensitive coating; and uniformly coating the surface of thermosensitive base paper with the thermosensitive coating by using a coating machine, and drying to obtain the environment-friendly phenol-free thermosensitive paper label material. The environment-friendly phenol-free thermo-sensitive paper label material prepared by the invention has excellent wear resistance, antibacterial property, light resistance and flame retardance.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal paper, in particular to an environmentally friendly phenol-free thermal paper label material and a preparation method thereof. Background Art

[0002] As a type of information recording material, thermal recording paper has the characteristics of small and flexible printing device, single and cheap printing consumables, simple and convenient printing operation, quiet and fast printing process, and fine and clear printed products. It has been widely used in fax communications, medical imaging, financial bills, logistics labels and other fields.

[0003] Ordinary thermal paper is the most basic type of thermal paper. Its production technology is relatively mature, and the paper structure is relatively simple. Most of these are two-component, colorless, and dye-based thermal papers. While this type of thermal paper is generally relatively inexpensive, it has a short shelf life and can fade to varying degrees under light, causing the text to become blurred or even disappear. Thermal paper is also susceptible to scratches and abrasion during use, resulting in blurred text. This is highly unfavorable for use in applications requiring high accuracy, such as logistics, healthcare, lottery, food labeling, and functional packaging.

[0004] In addition, in the preparation process of thermal paper, bisphenol A, which has excellent color development properties and is inexpensive, is often used as a color developer. However, bisphenol A is an endocrine disruptor that produces various toxic effects in the human body and the environment. Even with simple contact with thermal paper, bisphenol A may enter the body through the skin. Using it in thermal paper will pose potential risks to human health and the environment.

[0005] Based on the above problems, an environmentally friendly phenol-free thermal paper label material was invented. It uses environmentally friendly and pollution-free natural colorants instead of bisphenol A colorants, and improves the light resistance and wear resistance of thermal paper, making thermal paper more environmentally friendly and safe, while also improving the overall performance of thermal paper. Summary of the Invention

[0006] The purpose of the present invention is to provide an environmentally friendly phenol-free thermal paper label material and a preparation method thereof, so as to solve the problems existing in the prior art.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] An environmentally friendly phenol-free thermal paper label material is provided. The environmentally friendly phenol-free thermal paper label material is prepared by reacting pre-modified fiber and N,N-dimethylpropane-1-amine to obtain modified cellulose; reacting pre-modified silica, phosphorous acid, and formaldehyde to obtain modified silica; uniformly mixing functional styrene-butadiene emulsion, modified cellulose, modified silica, a color developer, a lubricant, a sensitizer, and a colorless pigment to prepare a thermal coating; and uniformly coating the thermal coating on the surface of a thermal base paper using a coating machine and drying to obtain the environmentally friendly phenol-free thermal paper label material.

[0009] The pre-modified fiber is prepared by reacting pre-treated fiber and 4-(2-chloroethoxy)benzophenone;

[0010] The pretreated fiber is prepared by reacting cellulose and cyanoacetic acid;

[0011] The pre-modified silica is prepared by reacting silica and diethylenetriaminopropyltrimethoxysilane;

[0012] The functional styrene-butadiene emulsion is prepared by micro-emulsion polymerization using low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane and acrylic acid as polymerization monomers;

[0013] The developer is tannin;

[0014] The lubricant is paraffin;

[0015] The sensitizer is tetramethyl diphenyl ethane;

[0016] The colorless pigment is 2-phenylamino-3-methyl-6-dibutylaminofluoran.

[0017] A method for preparing an environmentally friendly phenol-free thermal paper label material, the method comprising the following steps:

[0018] (1) low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane, and emulsifier solution are mixed uniformly in a mass ratio of 1: (0.5-0.6): (0.3-0.4): (4-5), stirred at 10-30°C and 800-1000 r / min for 20-30 min, placed in an ultra-high pressure homogenizer for shear emulsification for 15-25 min, and a monomer microemulsion is prepared; 1 / 3 of the monomer microemulsion and 1 / 3 of the initiator solution are mixed uniformly, stirred at 55-65°C and 200-300 r / min for 55-65 min, and a pre-emulsion is prepared; the remaining monomer microemulsion, the remaining initiator solution, and the acrylic acid solution are uniformly added dropwise to the pre-emulsion within 1 h, the stirring reaction is continued for 2-3 h, and the functional styrene-butadiene emulsion is prepared;

[0019] (2) The pretreated fiber, 4-(2-chloroethoxy)benzophenone and n-heptane were mixed uniformly in a mass ratio of 1:(2-3):(12-14), stirred at 50-60°C and 200-300 r / min for 8-10 min, heated to 95-97°C, and the catalyst solution (0.11-0.13 times the mass of the pretreated cellulose) was added dropwise at a constant speed within 20 min. After the addition was completed, the mixture was stirred for 5-6 h, cooled to room temperature, and washed with anhydrous ethanol by centrifugation for 3 min. to 5 times, and drying at 50-60° C. for 8-10 hours under vacuum conditions to obtain pre-modified cellulose; uniformly mixing pre-modified cellulose, N,N-dimethylpropane-1-amine, and tetrahydrofuran in a mass ratio of 1:(2-3):(10-12), stirring at 50-60° C. and 200-300 r / min for 1-2 hours, cooling to room temperature, washing with anhydrous ethanol by centrifugation 3-5 times, and drying at 50-60° C. for 8-10 hours under vacuum conditions to obtain modified cellulose;

[0020] (3) pre-modified silica, phosphorous acid, and deionized water were mixed uniformly in a mass ratio of 1:(2-3):(20-22), ultrasonically dispersed for 20-30 min, added with an equal molar amount of formaldehyde to phosphorous acid, stirred and refluxed at 103-105° C. and 200-300 r / min for 1-2 h, cooled to room temperature, filtered, washed with deionized water 3-5 times, and dried under vacuum at 50-60° C. for 6-8 h to obtain modified silica;

[0021] (4) According to the mass ratio, 32-36 parts of functional styrene butadiene emulsion, 6-7 parts of modified cellulose, 16-18 parts of modified silica, 18-20 parts of tannin, 5-6 parts of paraffin wax, 8-10 parts of tetramethyl diphenyl ethane, and 9-11 parts of 2-phenylamino-3-methyl-6-dibutylamino fluoran are weighed; the functional styrene butadiene emulsion, modified cellulose, modified silica, tannin, paraffin wax, tetramethyl diphenyl ethane, and 2-phenylamino-3-methyl-6-dibutylamino fluoran are uniformly mixed, and stirred at 30-40°C and 400-500 r / min for 8-10 minutes to prepare a thermal coating; the thermal coating is evenly coated on the surface of the thermal base paper using a coating machine by a wire rod coating method, and the coating amount is 4-5 g / m 2 , under vacuum conditions, dried at 64-66°C for 7-8 hours to obtain environmentally friendly phenol-free thermal paper label material.

[0022] As an optimization, the model of the low molecular weight liquid polybutadiene in step (1) is NISSO-PB BI-2000.

[0023] As an optimization, the preparation method of the emulsifier solution in step (1) is: sodium lauryl sulfate and deionized water are mixed uniformly in a mass ratio of 1: (20-22) to prepare an emulsifier solution.

[0024] As an optimization, the preparation method of the initiator solution in step (1) is: 0.04 to 0.06 times the mass of low molecular weight liquid polybutadiene ammonium persulfate and deionized water are mixed uniformly in a mass ratio of 1: (5 to 6) to prepare an initiator solution.

[0025] As an optimization, the preparation method of the acrylic acid solution in step (1) is: 0.3 to 0.4 times the mass of low molecular weight liquid polybutadiene and deionized water are mixed uniformly in a mass ratio of 1: (4 to 5) to prepare an acrylic acid solution.

[0026] As an optimization, the preparation method of the pretreated cellulose in step (2) is as follows: cellulose and deionized water are uniformly mixed in a mass ratio of 1:(16-18), the pH is adjusted to 3-4 with a 1 mol / L hydrochloric acid aqueous solution, the mixture is placed in a high-pressure reactor, stirred at 118-122° C. and 200-300 r / min for 18-20 min, cyanoacetic acid in an amount of 1.3-1.5 times the mass of the cellulose is added, stirring is continued for 1-2 h, the mixture is cooled to room temperature, centrifuged and washed with deionized water for 3-5 times, and dried at 50-60° C. under vacuum conditions for 8-10 h to obtain the pretreated cellulose.

[0027] As an optimization, the cellulose type is HEC HD30000.

[0028] As an optimization, the preparation method of the catalyst solution in step (2) is: ammonium acetate and acetic acid are uniformly mixed in a mass ratio of 1:(2-3) to prepare a catalyst solution.

[0029] As an optimization, the CAS number of 4-(2-chloroethoxy)benzophenone in step (2) is 3439-73-4; the structural formula is as follows:

[0030]

[0031] As an optimization, the preparation method of the pre-modified silica in step (3) is as follows: diethylenetriaminopropyltrimethoxysilane, a hydrochloric acid aqueous solution with a mass fraction of 10% to 12%, and anhydrous ethanol are mixed uniformly in a mass ratio of 1: (0.6 to 0.8): (8 to 10), stirred at 10 to 30°C and 200 to 300r / min for 28 to 32min to prepare a silane hydrolyzate; silica and deionized water are mixed uniformly in a mass ratio of 1: (60 to 70), ultrasonically dispersed for 1 to 2h, 5 to 6 times the mass of silica is added to the silane hydrolyzate, stirred at 50 to 60°C and 200 to 300r / min for 3 to 4h, filtered, and dried at 60 to 70°C under vacuum conditions for 8 to 10h to obtain pre-modified silica.

[0032] As an optimization, the particle size of the silicon dioxide in step (3) is 1000 mesh.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention prepares an environmentally friendly phenol-free thermal paper label material. Low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane and acrylic acid are used as polymerization monomers, and a microdroplet emulsion polymerization method is adopted to prepare a functional styrene-butadiene emulsion. Cellulose and cyanoacetic acid are reacted to prepare pretreated cellulose. The pretreated fiber and 4-(2-chloroethoxy)benzophenone are reacted to prepare premodified cellulose. The premodified fiber and N,N-dimethylpropane-1-amine are reacted to prepare modified cellulose. Silicon dioxide and diethylenetriaminepropyltrimethoxysilane are reacted to prepare premodified silicon dioxide. The premodified silicon dioxide, phosphorous acid and formaldehyde are reacted to prepare modified silicon dioxide. The functional styrene-butadiene emulsion, modified cellulose, modified silicon dioxide, a color developer, a lubricant, a sensitizer and a colorless pigment are uniformly mixed to prepare a thermal coating. The thermal coating is uniformly coated on the surface of thermal base paper by a coating machine and dried to prepare the environmentally friendly phenol-free thermal paper label material.

[0035] First, a functional styrene-butadiene emulsion was prepared by micro-emulsion polymerization using low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane, and acrylic acid as polymerization monomers; Si-O-Si bonds and carboxyl groups were introduced into the molecular chain of the latex particles; the introduction of Si-O-Si bonds can improve the flame retardant properties of the environmentally friendly phenol-free thermal paper label material; the carboxyl groups introduced into the molecular chain of the latex particles can combine with the positive and negative charges of the quaternary ammonium salt introduced on the modified cellulose to form a cross-linked structure, preventing the material from being torn by external shear forces, thereby improving the wear resistance of the environmentally friendly phenol-free thermal paper label material.

[0036] Secondly, cellulose and cyanoacetic acid are reacted to obtain pretreated cellulose, and a cyanoacetic acid ester structure is generated on the pretreated cellulose; the cyanoacetic acid ester structure on the pretreated fiber is reacted with 4-(2-chloroethoxy)benzophenone to obtain pre-modified cellulose, and an octocrylene derivative structure is generated on the pre-modified cellulose, and a chlorine atom is introduced; the octocrylene derivative structure can absorb ultraviolet light, thereby improving the light resistance of the environmentally friendly phenol-free thermal paper label material; the chlorine atom on the pre-modified fiber is reacted with N,N-dimethylpropane-1-amine to obtain modified cellulose, and a quaternary ammonium salt structure is generated on the modified cellulose. The quaternary ammonium salt is a cationic antibacterial agent, which can improve the antibacterial properties of the environmentally friendly phenol-free thermal paper label material. At the same time, it can also combine with the carboxyl group on the functional styrene-butadiene emulsion and the phosphate group on the modified silica through positive and negative charges to form a cross-linked network structure, thereby preventing the material from being torn by external shear force and improving the wear resistance of the environmentally friendly phenol-free thermal paper label material.

[0037] Finally, silica and diethylenetriaminopropyltrimethoxysilane are reacted to prepare pre-modified silica, and a large number of amino groups are introduced on the surface of the pre-modified silica; the amino groups on the pre-modified silica are reacted with phosphorous acid and formaldehyde to prepare modified silica; a large number of phosphate groups are introduced on the surface of the modified silica. The introduction of phosphate groups can improve the flame retardant properties of the environmentally friendly phenol-free thermal paper label material, and at the same time combine with the positive and negative charges of the quaternary ammonium salt on the modified cellulose to form a cross-linked network structure to prevent the material from being torn by external shear forces, thereby improving the wear resistance of the environmentally friendly phenol-free thermal paper label material.

[0038] In addition, when preparing the thermal-sensitive coating, the present invention uses tannin as a color developer instead of the traditional color developer bisphenol A. Bisphenol A is an endocrine disruptor, and its structure and function are very similar to those of the human hormone estradiol. Bisphenol A can mimic endogenous hormones and act as a hormone antagonist, causing a false increase in hormones in the body, affecting synthesis, secretion, transport and binding, thereby having a significant impact on health. Tannin is the substance richest in natural phenols besides lignin. It comes from plant bark, leaves, roots, branches and other parts, and has a similar structure to synthetic phenols. It can replace bisphenol A in thermal paper to play a coloring role, and has the advantages of being healthy and green and environmentally friendly. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Example 1:

[0041] A method for preparing an environmentally friendly phenol-free thermal paper label material, the method comprising the following steps:

[0042] (1) Sodium lauryl sulfate and deionized water were mixed at a mass ratio of 1:20 to prepare an emulsifier solution; low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane and emulsifier solution were mixed at a mass ratio of 1:0.5:0.3:4, stirred at 10°C and 800 r / min for 30 minutes, placed in an ultra-high pressure homogenizer for shear emulsification for 15 minutes to prepare a monomer microemulsion; ammonium persulfate (0.04 times the mass of low molecular weight liquid polybutadiene) and deionized water were mixed at a mass ratio of 1:5 The monomer microemulsion and the initiator solution were mixed evenly to prepare an initiator solution; acrylic acid with a mass ratio of 0.3 times that of the low molecular weight liquid polybutadiene and deionized water were mixed evenly in a mass ratio of 1:4 to prepare an acrylic acid solution; 1 / 3 of the monomer microemulsion and 1 / 3 of the initiator solution were mixed evenly, and stirred at 55°C and 200r / min for 65min to prepare a pre-emulsion; the remaining monomer microemulsion, the remaining initiator solution and the acrylic acid solution were uniformly added dropwise to the pre-emulsion within 1h, and the stirring reaction was continued for 3h, and the functional styrene-butadiene emulsion was prepared;

[0043] (2) Cellulose and deionized water were mixed in a mass ratio of 1:16, the pH was adjusted to 3 with a 1 mol / L hydrochloric acid aqueous solution, the mixture was placed in a high-pressure reactor, stirred at 118 ° C and 200 r / min for 20 min, cyanoacetic acid 1.3 times the mass of the cellulose was added, and the mixture was stirred for 2 h. The mixture was cooled to room temperature, washed three times with deionized water by centrifugation, and dried at 50 ° C under vacuum conditions for 10 h to obtain pretreated cellulose; ammonium acetate and acetic acid were mixed in a mass ratio of 1:2 to prepare a catalyst solution; pretreated fiber, 4-(2-chloroethoxy) benzophenone and n-heptane were mixed in a mass ratio of 1:2:12 to prepare a catalyst solution; ℃, 200r / min, stirring for 10min, heating to 95℃, and uniformly adding a catalyst solution of 0.11 times the mass of the pretreated cellulose dropwise within 20min. After the addition is completed, stirring and reacting for 6h, cooling to room temperature, centrifugally washing with anhydrous ethanol 3 times, and drying at 50℃ for 10h under vacuum conditions to obtain pre-modified cellulose; pre-modified cellulose, N,N-dimethylpropane-1-amine, and tetrahydrofuran are uniformly mixed in a mass ratio of 1:2:10, stirring and reacting at 50℃, 200r / min for 2h, cooling to room temperature, centrifugally washing with anhydrous ethanol 3 times, and drying at 50℃ for 10h under vacuum conditions to obtain modified cellulose;

[0044] (3) Diethylenetriaminopropyltrimethoxysilane, 10% hydrochloric acid aqueous solution, and anhydrous ethanol were mixed in a mass ratio of 1:0.6:8, stirred at 10°C and 200 r / min for 32 minutes to prepare a silane hydrolyzate; silica and deionized water were mixed in a mass ratio of 1:60, ultrasonically dispersed for 1 hour, 5 times the mass of silica was added to the silane hydrolyzate, stirred at 50°C and 200 r / min for 4 hours, filtered, and dried at 60°C under vacuum conditions for 10 hours to prepare pre-modified silica; pre-modified silica, phosphorous acid, and deionized water were mixed in a mass ratio of 1:2:20, ultrasonically dispersed for 20 minutes, and an equal molar amount of formaldehyde was added to the phosphorous acid, stirred and refluxed at 103°C and 200 r / min for 2 hours, cooled to room temperature, filtered, washed with deionized water 3 times, and dried at 50°C under vacuum conditions for 8 hours to prepare modified silica;

[0045] (4) According to the mass ratio, 32 parts of functional styrene butadiene emulsion, 6 parts of modified cellulose, 16 parts of modified silica, 18 parts of tannin, 5 parts of paraffin, 8 parts of tetramethyl diphenyl ethane, and 9 parts of 2-phenylamino-3-methyl-6-dibutylamino fluoran were weighed; the functional styrene butadiene emulsion, modified cellulose, modified silica, tannin, paraffin, tetramethyl diphenyl ethane, and 2-phenylamino-3-methyl-6-dibutylamino fluoran were mixed evenly, and stirred at 30°C and 400 r / min for 10 minutes to prepare a thermal coating; the thermal coating was evenly coated on the surface of the thermal base paper using a coating machine by a wire rod coating method, and the coating amount was 4g / m 2 , dried at 64 ° C under vacuum conditions for 8 h to obtain environmentally friendly phenol-free thermal paper label material.

[0046] Example 2:

[0047] A method for preparing an environmentally friendly phenol-free thermal paper label material, the method comprising the following steps:

[0048] (1) Sodium lauryl sulfate and deionized water were mixed at a mass ratio of 1:21 to prepare an emulsifier solution; low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane and emulsifier solution were mixed at a mass ratio of 1:0.55:0.35:4.5, stirred at 20°C and 900 r / min for 25 minutes, placed in an ultra-high pressure homogenizer for shear emulsification for 20 minutes to prepare a monomer microemulsion; ammonium persulfate (0.05 times the mass of low molecular weight liquid polybutadiene) and deionized water were mixed at a mass ratio of 1:5.5 to prepare a monomer microemulsion; The monomer microemulsion and the initiator solution were mixed evenly to prepare an initiator solution; acrylic acid with a mass ratio of 0.35 times that of the low molecular weight liquid polybutadiene and deionized water were mixed evenly at a mass ratio of 1:4.5 to prepare an acrylic acid solution; 1 / 3 of the monomer microemulsion and 1 / 3 of the initiator solution were mixed evenly, and stirred at 60°C and 250r / min for 60min to prepare a pre-emulsion; the remaining monomer microemulsion, the remaining initiator solution and the acrylic acid solution were uniformly added dropwise to the pre-emulsion within 1h, and the stirring reaction was continued for 2.5h, and the functional styrene-butadiene emulsion was prepared;

[0049] (2) Cellulose and deionized water were mixed in a mass ratio of 1:17, the pH was adjusted to 3.5 with a 1 mol / L hydrochloric acid aqueous solution, and the mixture was placed in a high-pressure reactor, stirred at 120 ° C and 250 r / min for 19 minutes, cyanoacetic acid 1.4 times the mass of the cellulose was added, and the mixture was stirred for 1.5 hours. The mixture was cooled to room temperature, washed 4 times with deionized water by centrifugation, and dried at 55 ° C under vacuum conditions for 9 hours to obtain pretreated cellulose; ammonium acetate and acetic acid were mixed in a mass ratio of 1:2.5 to prepare a catalyst solution; pretreated fiber, 4-(2-chloroethoxy) benzophenone, and n-heptane were mixed in a mass ratio of 1:2.5:13 to prepare a catalyst solution; The mixture was stirred at 55°C and 250 r / min for 9 minutes, and then heated to 96°C. A catalyst solution in an amount 0.12 times the mass of the pretreated cellulose was added dropwise at a uniform rate within 20 minutes. After the addition was completed, the mixture was stirred and reacted for 5.5 hours. The mixture was cooled to room temperature, washed with anhydrous ethanol by centrifugation 4 times, and dried at 55°C under vacuum conditions for 9 hours to obtain pre-modified cellulose. The pre-modified cellulose, N,N-dimethylpropane-1-amine, and tetrahydrofuran were mixed uniformly in a mass ratio of 1:2.5:11, stirred and reacted at 55°C and 250 r / min for 1.5 hours, cooled to room temperature, washed with anhydrous ethanol by centrifugation 4 times, and dried at 55°C under vacuum conditions for 9 hours to obtain modified cellulose.

[0050] (3) Diethylenetriaminopropyltrimethoxysilane, 11% hydrochloric acid aqueous solution, and anhydrous ethanol were mixed in a mass ratio of 1:0.7:9, stirred at 20°C and 250 r / min for 30 min to prepare a silane hydrolyzate; silicon dioxide and deionized water were mixed in a mass ratio of 1:65, ultrasonically dispersed for 1.5 h, and 5.5 times the mass of silicon dioxide was added to the silane hydrolyzate, and stirred at 55°C and 250 r / min for 3 min. .5h, filtered, and dried at 65°C under vacuum conditions for 9h to obtain pre-modified silica; the pre-modified silica, phosphorous acid, and deionized water were mixed uniformly in a mass ratio of 1:2.5:21, ultrasonically dispersed for 25min, and an equal molar amount of formaldehyde was added to the phosphorous acid. The mixture was stirred and refluxed at 104°C and 250r / min for 1.5h, cooled to room temperature, filtered, washed with deionized water 4 times, and dried at 55°C under vacuum conditions for 7h to obtain modified silica;

[0051] (4) According to the mass ratio, 34 parts of functional styrene butadiene emulsion, 6.5 parts of modified cellulose, 17 parts of modified silica, 19 parts of tannin, 5.5 parts of paraffin, 9 parts of tetramethyl diphenyl ethane, and 10 parts of 2-phenylamino-3-methyl-6-dibutylamino fluoran were weighed; the functional styrene butadiene emulsion, modified cellulose, modified silica, tannin, paraffin, tetramethyl diphenyl ethane, and 2-phenylamino-3-methyl-6-dibutylamino fluoran were mixed evenly, and stirred at 35°C and 450r / min for 9 minutes to prepare a thermal coating; the thermal coating was evenly coated on the surface of the thermal base paper using a coating machine by a wire rod coating method, and the coating amount was 4.5g / m 2 , dried at 65℃ for 7.5h under vacuum conditions to obtain environmentally friendly phenol-free thermal paper label material.

[0052] Example 3:

[0053] A method for preparing an environmentally friendly phenol-free thermal paper label material, the method comprising the following steps:

[0054] (1) Sodium lauryl sulfate and deionized water were mixed at a mass ratio of 1:22 to prepare an emulsifier solution; low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane and emulsifier solution were mixed at a mass ratio of 1:0.6:0.4:5, stirred at 30°C and 1000 r / min for 20 minutes, placed in an ultra-high pressure homogenizer for shear emulsification for 25 minutes to prepare a monomer microemulsion; ammonium persulfate (0.06 times the mass of low molecular weight liquid polybutadiene) and deionized water were mixed at a mass ratio of 1:6 The monomer microemulsion and the initiator solution were mixed evenly to prepare an initiator solution; acrylic acid with a mass ratio of 0.4 times that of the low molecular weight liquid polybutadiene and deionized water were mixed evenly at a mass ratio of 1:5 to prepare an acrylic acid solution; 1 / 3 of the monomer microemulsion and 1 / 3 of the initiator solution were mixed evenly, and stirred at 65°C and 300r / min for 55min to prepare a pre-emulsion; the remaining monomer microemulsion, the remaining initiator solution and the acrylic acid solution were uniformly added dropwise to the pre-emulsion within 1h, and the stirring reaction was continued for 2h, and the functional styrene-butadiene emulsion was prepared.

[0055] (2) Cellulose and deionized water were mixed in a mass ratio of 1:18, the pH was adjusted to 4 with a 1 mol / L hydrochloric acid aqueous solution, and the mixture was placed in a high-pressure reactor, stirred at 122 ° C and 300 r / min for 18 min, cyanoacetic acid 1.5 times the mass of the cellulose was added, and the mixture was stirred for 1 h. The mixture was cooled to room temperature, washed 5 times with deionized water by centrifugation, and dried at 60 ° C under vacuum conditions for 8 h to obtain pretreated cellulose; ammonium acetate and acetic acid were mixed in a mass ratio of 1:3 to prepare a catalyst solution; pretreated fiber, 4-(2-chloroethoxy) benzophenone, and n-heptane were mixed in a mass ratio of 1:3:14 to prepare a catalyst solution; 0℃, 300r / min, stirring for 8min, heating to 97℃, uniformly adding 0.13 times the mass of the pretreated cellulose catalyst solution dropwise within 20min, after the addition is complete, continuing to stir and react for 5h, cooling to room temperature, centrifugally washing with anhydrous ethanol 5 times, and drying at 60℃ under vacuum conditions for 8h to obtain pre-modified cellulose; pre-modified cellulose, N,N-dimethylpropane-1-amine, and tetrahydrofuran are uniformly mixed in a mass ratio of 1:3:12, stirring and reacting at 60℃, 300r / min for 1h, cooling to room temperature, centrifugally washing with anhydrous ethanol 5 times, and drying at 60℃ under vacuum conditions for 8h to obtain modified cellulose;

[0056] (3) Diethylenetriaminopropyltrimethoxysilane, 12% hydrochloric acid aqueous solution, and anhydrous ethanol were mixed in a mass ratio of 1:0.8:10, stirred at 30°C, 300r / min for 28min, and prepared into a silane hydrolyzate; silica and deionized water were mixed in a mass ratio of 1:70, ultrasonically dispersed for 2h, 6 times the mass of silica was added into the silane hydrolyzate, stirred at 60°C, 300r / min for 3h, filtered, and dried at 70°C under vacuum for 8h to obtain pre-modified silica; pre-modified silica, phosphorous acid, and deionized water were mixed in a mass ratio of 1:3:22, ultrasonically dispersed for 30min, an equal molar amount of formaldehyde was added into the phosphorous acid, stirred and refluxed at 105°C, 300r / min for 1h, cooled to room temperature, filtered, washed with deionized water 5 times, and dried at 60°C under vacuum for 6h to obtain modified silica;

[0057] (4) According to the mass ratio, 36 parts of functional styrene butadiene emulsion, 7 parts of modified cellulose, 18 parts of modified silica, 20 parts of tannin, 6 parts of paraffin, 10 parts of tetramethyl diphenyl ethane, and 11 parts of 2-phenylamino-3-methyl-6-dibutylamino fluoran were weighed; the functional styrene butadiene emulsion, modified cellulose, modified silica, tannin, paraffin, tetramethyl diphenyl ethane, and 2-phenylamino-3-methyl-6-dibutylamino fluoran were mixed evenly, and stirred at 40°C and 500 r / min for 8 minutes to prepare a thermal coating; the thermal coating was evenly coated on the surface of the thermal base paper using a coating machine by a wire rod coating method, and the coating amount was 5g / m 2 , dried at 66 ° C for 7 h under vacuum conditions to obtain environmentally friendly phenol-free thermal paper label material.

[0058] Comparative Example 1:

[0059] The difference between the preparation method of the environmentally friendly phenol-free thermal paper label material of Comparative Example 1 and Example 2 lies in the difference in step (1). Step (1) is modified as follows: sodium lauryl sulfate and deionized water are mixed uniformly in a mass ratio of 1:21 to prepare an emulsifier solution; low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane, and emulsifier solution are mixed uniformly in a mass ratio of 1:0.55:0.35:4.5, stirred at 20°C and 900r / min for 25min, and placed in an ultra-high pressure homogenizer for shear emulsification for 2 min. 0 min to prepare a monomer microemulsion; ammonium persulfate (0.05 times the mass of low molecular weight liquid polybutadiene) and deionized water are mixed uniformly in a mass ratio of 1:5.5 to prepare an initiator solution; 1 / 3 of the monomer microemulsion and 1 / 3 of the initiator solution are mixed uniformly, and stirred at 60°C, 250 rpm for 60 min to prepare a pre-emulsion; the remaining monomer microemulsion and the remaining initiator solution are added dropwise to the pre-emulsion at a uniform rate over 1 h, and the stirring reaction is continued for 2.5 h. The functional styrene-butadiene emulsion is prepared. The remaining steps are the same as in Example 2.

[0060] Comparative Example 2:

[0061] The preparation method of the environmentally friendly phenol-free thermal paper label material of Comparative Example 2 is different from that of Example 2 in that step (1) is different. Step (1) is modified as follows: sodium lauryl sulfate and deionized water are mixed uniformly in a mass ratio of 1:21 to prepare an emulsifier solution; low molecular weight liquid polybutadiene, styrene, and emulsifier solution are mixed uniformly in a mass ratio of 1:0.55:4.5, stirred at 20°C and 900r / min for 25min, placed in an ultra-high pressure homogenizer for shear emulsification for 20min, and a monomer microemulsion is prepared; ammonium persulfate with a mass of 0.05 times that of the low molecular weight liquid polybutadiene is added. The following steps were repeated: 1) mixing the monomer microemulsion with the initiator solution in a mass ratio of 1:5.5 and deionized water to prepare an initiator solution; 2) mixing acrylic acid (0.35 times the mass of the low molecular weight liquid polybutadiene) with deionized water in a mass ratio of 1:4.5 to prepare an acrylic acid solution; 3) mixing 1 / 3 of the monomer microemulsion with 1 / 3 of the initiator solution, stirring at 60°C and 250 rpm for 60 minutes to prepare a pre-emulsion; 4) adding the remaining monomer microemulsion, the remaining initiator solution, and the acrylic acid solution to the pre-emulsion at a uniform rate over 1 hour, continuing the stirring reaction for 2.5 hours, and cooling to room temperature to prepare a functional styrene-butadiene emulsion. The remaining steps were the same as in Example 2.

[0062] Comparative Example 3:

[0063] The preparation method of the environmentally friendly phenol-free thermal paper label material of Comparative Example 3 is different from that of Example 2 only in step (2). Step (2) is modified as follows: cellulose and deionized water are mixed uniformly in a mass ratio of 1:17, the pH is adjusted to 3.5 with a 1 mol / L hydrochloric acid aqueous solution, placed in a high-pressure reactor, stirred at 120°C and 250 r / min for 19 minutes, cyanoacetic acid 1.4 times the mass of cellulose is added, stirring is continued for 1.5 hours, cooled to room temperature, centrifuged and washed 4 times with deionized water, and dried at 55°C under vacuum conditions for 9 hours to prepare a product. Pretreated cellulose was obtained; ammonium acetate and acetic acid were mixed uniformly in a mass ratio of 1:2.5 to prepare a catalyst solution; the pretreated fiber, benzophenone, and n-heptane were mixed uniformly in a mass ratio of 1:2.5:13, stirred at 55°C and 250 rpm for 9 minutes, heated to 96°C, and the catalyst solution (0.12 times the mass of the pretreated cellulose) was added dropwise at a constant rate over 20 minutes. After the addition was complete, the mixture was stirred and reacted for 5.5 hours. The mixture was cooled to room temperature, washed with anhydrous ethanol by centrifugation four times, and dried under vacuum at 55°C for 9 hours to obtain modified cellulose. The remaining steps were the same as in Example 2.

[0064] Comparative Example 4:

[0065] The preparation method of the environmentally friendly phenol-free thermal paper label material of Comparative Example 4 differs from that of Example 2 only in that step (2) is not performed, and step (4) is modified as follows: 34 parts of functional styrene butadiene emulsion, 6.5 parts of cellulose, 17 parts of modified silica, 19 parts of tannin, 5.5 parts of paraffin, 9 parts of tetramethyl diphenyl ethane, and 10 parts of 2-phenylamino-3-methyl-6-dibutylamino fluoran are weighed in parts by mass; the functional styrene butadiene emulsion, cellulose, modified silica, tannin, paraffin, tetramethyl diphenyl ethane, and 2-phenylamino-3-methyl-6-dibutylamino fluoran are uniformly mixed, and stirred at 35° C. and 450 r / min for 9 minutes to prepare a thermal coating; the thermal coating is evenly coated on the surface of the thermal base paper using a coating machine using a wire rod coating method, and the coating amount is 4.5 g / m 2 The mixture was dried at 65° C. for 7.5 h under vacuum conditions to obtain an environmentally friendly phenol-free thermal paper label material. The remaining steps were the same as those in Example 2.

[0066] Comparative Example 5:

[0067] The preparation method of the environmentally friendly phenol-free thermal paper label material of Comparative Example 5 is different from that of Example 2 in that step (3) is not performed, and step (4) is modified as follows: 34 parts of functional styrene butadiene emulsion, 6.5 parts of modified cellulose, 17 parts of silicon dioxide, 19 parts of tannin, 5.5 parts of paraffin, 9 parts of tetramethyl diphenyl ethane, and 10 parts of 2-phenylamino-3-methyl-6-dibutylamino fluoran are weighed in parts by mass; the functional styrene butadiene emulsion, modified cellulose, silicon dioxide, tannin, paraffin, tetramethyl diphenyl ethane, and 2-phenylamino-3-methyl-6-dibutylamino fluoran are uniformly mixed, and stirred at 35° C. and 450 r / min for 9 minutes to prepare a thermal coating; the thermal coating is evenly coated on the surface of the thermal base paper using a coating machine using a wire rod coating method, and the coating amount is 4.5 g / m 2 , dried at 65℃ for 7.5h under vacuum conditions to obtain environmentally friendly phenol-free thermal paper label material.

[0068] Test Example 1

[0069] Lightfastness test

[0070] Test method:

[0071] Group 1: The examples and comparative examples were printed, and then irradiated with a 200W UV lamp for 1 hour. The color of the printed text and pattern was observed under a D65 light source.

[0072] Group 2: The examples and comparative examples were irradiated with a 200W UV lamp for 1 hour, and the printed text and pattern colors were observed under a D65 light source;

[0073] The colors of two groups of experimental samples of the same sample were compared with the standard color card to determine the grayscale level (level 1-9). The results are shown in Table 1.

[0074] Table 1

[0075]

[0076] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 1, it can be found that the environmentally friendly phenol-free thermal paper label material prepared in the present invention has good light resistance.

[0077] By comparison, the grayscale levels of the first and second groups of Examples 1 to 3 are greater than the grayscale levels of the first and second groups of Comparative Example 4, indicating that cellulose and cyanoacetic acid are reacted to prepare pretreated cellulose, and a cyanoacetate structure is generated on the pretreated cellulose; the cyanoacetate structure on the pretreated fiber is reacted with 4-(2-chloroethoxy)benzophenone to prepare pre-modified cellulose, and an octocrylene derivative structure is generated on the pre-modified cellulose; the octocrylene derivative structure can absorb ultraviolet light, thereby improving the light resistance of the environmentally friendly phenol-free thermal paper label material.

[0078] Test Example 2

[0079] Antibacterial performance testing

[0080] Test method: Cut the examples and comparative examples into 10 mm × 10 mm samples; activate the E. coli strain and prepare it to a concentration of 3 × 10 4 CFU / ml bacterial suspension; place the sample in the bacterial suspension and shake at 250 rpm for 10 minutes at room temperature. Dilute 1 ml of the bacterial suspension to 100-fold. Inoculate 1 ml of the diluted bacterial suspension onto agar medium and incubate at 37°C for 15 hours. Count the colonies according to the method in GB / T 15979 and calculate the inhibition rate. The results are shown in Table 2.

[0081] Table 2

[0082] Antibacterial rate (%) Antibacterial rate (%) Example 1 99.91 Comparative Example 1 99.88 Example 2 99.96 Comparative Example 2 99.85 Example 3 99.93 Comparative Example 3 71.28 Comparative Example 4 72.15 Comparative Example 5 99.87

[0083] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 2, it can be found that the environmentally friendly phenol-free thermal paper label material prepared by the present invention has good antibacterial properties.

[0084] By comparison, the antibacterial rates of Examples 1 to 3 are greater than those of Comparative Examples 3 to 4, indicating that the cyanoacetate structure on the pretreated fiber is reacted with 4-(2-chloroethoxy)benzophenone to prepare pre-modified cellulose, and chlorine atoms are introduced into the pre-modified cellulose; the chlorine atoms on the pre-modified fiber are reacted with N,N-dimethylpropane-1-amine to prepare modified cellulose, and a quaternary ammonium salt structure is generated on the modified cellulose. Quaternary ammonium salts are cationic antibacterial agents that can improve the antibacterial properties of environmentally friendly phenol-free thermal paper label materials.

[0085] Test Example 3

[0086] Wear resistance test

[0087] Test Method: Referring to GB / T 28210-2011 "Thermal Paper", the abrasion resistance of the examples and comparative examples was tested, and the results were expressed as image retention rate. The results are shown in Table 3.

[0088] Table 3

[0089]

[0090]

[0091] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 3, it can be found that the environmentally friendly phenol-free thermal paper label material prepared in the present invention has good wear resistance.

[0092] By comparison, the image retention rates of Examples 1 to 3 are greater than that of Comparative Example 1, indicating that a functional styrene-butadiene emulsion is prepared by a microdroplet emulsion polymerization method using low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane, and acrylic acid as polymerization monomers; carboxyl groups are introduced into the molecular chains of the latex particles; the carboxyl groups introduced into the molecular chains of the latex particles can combine with the positive and negative charges of the quaternary ammonium salt introduced on the modified cellulose to form a cross-linked structure, thereby preventing the material from being torn by external shear forces and improving the wear resistance of the environmentally friendly phenol-free thermal paper label material.

[0093] By comparison, the image retention rates of Examples 1 to 3 are greater than those of Comparative Examples 3 to 4, indicating that the cyanoacetate structure on the pretreated fiber is reacted with 4-(2-chloroethoxy)benzophenone to prepare pre-modified cellulose, and chlorine atoms are introduced into the pre-modified cellulose; the chlorine atoms on the pre-modified fiber are reacted with N,N-dimethylpropane-1-amine to prepare modified cellulose, and a quaternary ammonium salt structure is generated on the modified cellulose. The quaternary ammonium salt can combine with the carboxyl group on the functional styrene-butadiene emulsion and the phosphate group on the modified silica through positive and negative charges to form a cross-linked network structure, thereby preventing the material from being torn by external shear force and improving the wear resistance of the environmentally friendly phenol-free thermal paper label material.

[0094] By comparison, the image retention rates of Examples 1 to 3 are greater than that of Comparative Example 5, indicating that pre-modified silica is prepared by reacting silica and diethylenetriaminopropyltrimethoxysilane, and a large number of amino groups are introduced on the surface of the pre-modified silica; the amino groups on the pre-modified silica are reacted with phosphorous acid and formaldehyde to prepare modified silica; a large number of phosphate groups are introduced on the surface of the modified silica, and the phosphate groups combine with the positive and negative charges of the quaternary ammonium salt on the modified cellulose to form a cross-linked network structure, thereby preventing the material from being torn by external shear forces, thereby improving the wear resistance of the environmentally friendly phenol-free thermal paper label material.

[0095] Test Example 4

[0096] Flame retardant performance test

[0097] Test method:

[0098] The heat-sensitive coatings prepared in the Examples and Comparative Examples were poured into a mold, dried under vacuum at 65°C for 7 hours, and then removed from the mold. Standard bars were prepared from the Examples and Comparative Examples according to GB / T 2048, and the limiting oxygen index of the standard bars was tested. The results are shown in Table 4.

[0099] Table 4

[0100] Limiting oxygen index (%) Limiting oxygen index (%) Example 1 30.67 Comparative Example 1 30.61 Example 2 31.13 Comparative Example 2 27.48 Example 3 30.95 Comparative Example 3 30.38 Comparative Example 4 30.41 Comparative Example 5 24.62

[0101] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 4, it can be found that the environmentally friendly phenol-free thermal paper label material prepared in the present invention has good flame retardant properties.

[0102] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Example 2, indicating that a functional styrene-butadiene emulsion is prepared by a micro-emulsion polymerization method using low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane, and acrylic acid as polymerization monomers; and Si-O-Si bonds are introduced into the molecular chain of the latex particles. The introduction of Si-O-Si bonds can improve the flame retardant properties of environmentally friendly phenol-free thermal paper label materials.

[0103] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Example 5, indicating that pre-modified silica is prepared by reacting silica and diethylenetriaminopropyltrimethoxysilane, and a large number of amino groups are introduced on the surface of the pre-modified silica; the amino groups on the pre-modified silica are reacted with phosphorous acid and formaldehyde to prepare modified silica; and a large number of phosphate groups are introduced on the surface of the modified silica. The introduction of phosphate groups can improve the flame retardant properties of the environmentally friendly phenol-free thermal paper label material.

[0104] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An environmentally friendly phenol-free thermal paper label material, characterized in that: The environmentally friendly phenol-free thermal paper label material comprises the following steps: reacting pre-modified fiber and N,N-dimethylpropane-1-amine to obtain modified cellulose; reacting pre-modified silica, phosphorous acid, and formaldehyde to obtain modified silica; uniformly mixing functional styrene-butadiene emulsion, modified cellulose, modified silica, a color developer, a lubricant, a sensitizer, and a colorless pigment to prepare a thermal coating; and uniformly coating the thermal coating on the surface of a thermal base paper using a coating machine and drying the resulting thermal paper label material. The pre-modified fiber is prepared by reacting pre-treated fiber and 4-(2-chloroethoxy)benzophenone; The pretreated fiber is prepared by reacting cellulose and cyanoacetic acid; The pre-modified silica is prepared by reacting silica and diethylenetriaminopropyltrimethoxysilane; The functional styrene-butadiene emulsion is prepared by micro-emulsion polymerization using low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane and acrylic acid as polymerization monomers; The developer is tannin; The lubricant is paraffin; The sensitizer is tetramethyl diphenyl ethane; The colorless pigment is 2-phenylamino-3-methyl-6-dibutylaminofluoran.

2. A method for preparing an environmentally friendly phenol-free thermal paper label material, characterized in that: The preparation method of the environmentally friendly phenol-free thermal paper label material comprises the following preparation steps: (1) low molecular weight liquid polybutadiene, styrene, vinyl pentamethyldisiloxane, and emulsifier solution are mixed uniformly in a mass ratio of 1: (0.5-0.6): (0.3-0.4): (4-5), stirred at 10-30°C and 800-1000 r / min for 20-30 min, placed in an ultra-high pressure homogenizer for shear emulsification for 15-25 min, and a monomer microemulsion is prepared; 1 / 3 of the monomer microemulsion and 1 / 3 of the initiator solution are mixed uniformly, stirred at 55-65°C and 200-300 r / min for 55-65 min, and a pre-emulsion is prepared; the remaining monomer microemulsion, the remaining initiator solution, and the acrylic acid solution are uniformly added dropwise to the pre-emulsion within 1 h, the stirring reaction is continued for 2-3 h, and the functional styrene-butadiene emulsion is prepared; (2) The pretreated fiber, 4-(2-chloroethoxy)benzophenone and n-heptane were mixed uniformly in a mass ratio of 1:(2-3):(12-14), stirred at 50-60°C and 200-300 r / min for 8-10 min, heated to 95-97°C, and the catalyst solution (0.11-0.13 times the mass of the pretreated cellulose) was added dropwise at a constant speed within 20 min. After the addition was completed, the mixture was stirred for 5-6 h, cooled to room temperature, and washed with anhydrous ethanol by centrifugation for 3 min. to 5 times, and drying at 50-60° C. for 8-10 hours under vacuum conditions to obtain pre-modified cellulose; uniformly mixing pre-modified cellulose, N,N-dimethylpropane-1-amine, and tetrahydrofuran in a mass ratio of 1:(2-3):(10-12), stirring at 50-60° C. and 200-300 r / min for 1-2 hours, cooling to room temperature, washing with anhydrous ethanol by centrifugation 3-5 times, and drying at 50-60° C. for 8-10 hours under vacuum conditions to obtain modified cellulose; (3) pre-modified silica, phosphorous acid, and deionized water were mixed uniformly in a mass ratio of 1:(2-3):(20-22), ultrasonically dispersed for 20-30 min, added with an equal molar amount of formaldehyde to phosphorous acid, stirred and refluxed at 103-105° C. and 200-300 r / min for 1-2 h, cooled to room temperature, filtered, washed with deionized water 3-5 times, and dried under vacuum at 50-60° C. for 6-8 h to obtain modified silica; (4) According to the mass ratio, 32-36 parts of functional styrene butadiene emulsion, 6-7 parts of modified cellulose, 16-18 parts of modified silica, 18-20 parts of tannin, 5-6 parts of paraffin wax, 8-10 parts of tetramethyl diphenyl ethane, and 9-11 parts of 2-phenylamino-3-methyl-6-dibutylamino fluoran are weighed; the functional styrene butadiene emulsion, modified cellulose, modified silica, tannin, paraffin wax, tetramethyl diphenyl ethane, and 2-phenylamino-3-methyl-6-dibutylamino fluoran are uniformly mixed, and stirred at 30-40°C and 400-500 r / min for 8-10 minutes to prepare a thermal coating; the thermal coating is evenly coated on the surface of the thermal base paper using a coating machine by a wire rod coating method, and the coating amount is 4-5 g / m 2 , under vacuum conditions, dried at 64-66°C for 7-8 hours to obtain environmentally friendly phenol-free thermal paper label material.

3. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The model of the low molecular weight liquid polybutadiene in step (1) is NISSO-PB BI-2000.

4. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The preparation method of the emulsifier solution in step (1) is as follows: sodium lauryl sulfate and deionized water are uniformly mixed in a mass ratio of 1:(20-22) to prepare an emulsifier solution.

5. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The preparation method of the initiator solution in step (1) is as follows: 0.04 to 0.06 times the mass of low molecular weight liquid polybutadiene ammonium persulfate and deionized water are mixed uniformly in a mass ratio of 1: (5 to 6) to prepare an initiator solution.

6. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The preparation method of the acrylic acid solution in step (1) is as follows: acrylic acid with a mass of 0.3 to 0.4 times that of low molecular weight liquid polybutadiene and deionized water are uniformly mixed in a mass ratio of 1: (4 to 5) to prepare an acrylic acid solution.

7. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The preparation method of the pretreated cellulose in step (2) is as follows: cellulose and deionized water are uniformly mixed in a mass ratio of 1:(16-18), the pH is adjusted to 3-4 with a 1 mol / L hydrochloric acid aqueous solution, the mixture is placed in a high-pressure reactor, stirred at 118-122° C. and 200-300 r / min for 18-20 min, cyanoacetic acid in an amount of 1.3-1.5 times the mass of the cellulose is added, stirring is continued for 1-2 h, the mixture is cooled to room temperature, centrifuged and washed with deionized water for 3-5 times, and dried at 50-60° C. under vacuum conditions for 8-10 h to obtain the pretreated cellulose.

8. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The preparation method of the catalyst solution in step (2) is: ammonium acetate and acetic acid are uniformly mixed in a mass ratio of 1: (2 to 3) to prepare a catalyst solution.

9. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The preparation method of the pre-modified silica in step (3) is as follows: diethylenetriaminopropyltrimethoxysilane, a hydrochloric acid aqueous solution with a mass fraction of 10% to 12%, and anhydrous ethanol are mixed in a mass ratio of 1: (0.6 to 0.8): (8 to 10), stirred at 10 to 30°C and 200 to 300r / min for 28 to 32min to prepare a silane hydrolyzate; silica and deionized water are mixed in a mass ratio of 1: (60 to 70), ultrasonically dispersed for 1 to 2h, 5 to 6 times the mass of silica is added, and the reaction is stirred at 50 to 60°C and 200 to 300r / min for 3 to 4h, filtered, and dried at 60 to 70°C under vacuum conditions for 8 to 10h to obtain pre-modified silica.

10. The method for preparing an environmentally friendly phenol-free thermal paper label material according to claim 2, characterized in that: The particle size of the silicon dioxide in step (3) is 1000 mesh.

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