Organosilicon modified polyurethane emulsion, application thereof and back coating liquid for thermal transfer ribbon

Abstract

The invention provides organic silicon modified polyurethane emulsion, application thereof and back coating liquid for a thermal transfer ribbon, and particularly relates to the technical field of thermal transfer materials. The organic silicon modified polyurethane emulsion is mainly obtained by reaction of polyol, organic silicone oil, isocyanate, a catalyst and a chain extender. The preparation method comprises the following steps: adding isocyanate, a catalyst and an organic solvent into polyol and organic silicone oil, carrying out a prepolymerization reaction to obtain a prepolymer, and then adding a chain extender into the prepolymer solution to carry out a polymerization reaction to obtain the organic silicon modified polyurethane emulsion. The thermal decomposition temperature of the organic silicon modified polyurethane emulsion is 350 DEG C or above, the heat resistance and smoothness of organic silicon are brought into play, the high cohesiveness of polyurethane and a PET film can also be brought into play, and the heat transfer printing requirement is met by integrating the advantages of the organic silicon and the high cohesiveness of the polyurethane and the PET film.

Description

Technical Field

[0001] The invention relates to the technical field of thermal transfer materials, in particular to an organosilicon-modified polyurethane emulsion and an application thereof and a back coating liquid for a thermal transfer carbon ribbon. Background Art

[0002] The ribbon back coating is where the ribbon comes into direct contact with the printer's print head and its function is to protect the print head as the ribbon is unwound (from the coiled state), provide excellent heat transfer so that ink can be transferred to the media, and reduce the formation of static electricity that is harmful to the printer and printer operators, thereby extending the life of the print head.

[0003] Because the carbon ribbon needs to bear the high temperature generated instantly by the thermal print head during the thermal transfer process, a back coating needs to be applied on one side of the substrate. The back coating not only needs to have high heat resistance, but also needs to have good smoothness to ensure a smooth transfer process. More importantly, the back coating must have excellent adhesion to the substrate to ensure that the glue does not fall off during a long transfer process, avoiding contamination of the print head.

[0004] The earliest back coating used in China was a silicone resin / curing agent system, which has a high curing temperature, poor adhesion to the substrate, and a short service life, and can only be used for low-end products. At present, the back coating materials used for high-end products in the domestic TTR industry mostly rely on imports from Japan, the United States, South Korea, etc. The imported TTR back coating materials have problems such as easy shedding of high-temperature printing coatings, print head contamination, and poor weather resistance. The main reasons why the existing back coating is easy to fall off during high-temperature printing are: 1. The adhesion between the coating and the PET film is not enough; 2. The thermal stability of the coating is poor, which causes the polymer coating to decompose into small molecules during high-temperature printing, and then fall off and adhere to the print head.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the purposes of the present invention is to provide a silicone-modified polyurethane emulsion, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0007] A second object of the present invention is to provide an application of an organosilicon-modified polyurethane emulsion.

[0008] A third object of the present invention is to provide a back coating liquid for a thermal transfer carbon ribbon.

[0009] In order to solve the above technical problems, the present invention particularly adopts the following technical solutions: The first aspect of the present invention provides a silicone-modified polyurethane emulsion, which is mainly obtained by reacting polyol, silicone oil, isocyanate, catalyst and chain extender; The polyols include polyether polyols and / or polyester polyols; The organic silicone oil includes hydroxy silicone oil and / or amino silicone oil; The isocyanate comprises TDI and / or MDI; The catalyst includes dibutyltin dilaurate and / or stannous octoate; The chain extender includes at least one of 1,4-butanediol, 4,4'-methylenebis(2-chloroaniline), diethylene glycol, 1,6-hexanediol and neopentyl glycol; wherein isocyanate, a catalyst and an organic solvent are added to the polyol and the silicone oil to carry out a prepolymerization reaction to obtain a terminal -NCO group prepolymer, and then the chain extender is added to the prepolymer solution to carry out a polymerization reaction to obtain the silicone-modified polyurethane emulsion.

[0010] Furthermore, the amounts of the above raw materials are calculated by mass percentage as follows: 35% to 50% of polyol, 20% to 32% of silicone oil, 18% to 30% of isocyanate, 0.05%-0.15% of catalyst and 5% to 9% of chain extender; except for the catalyst, the sum of the amounts of the above raw materials is 100%.

[0011] Furthermore, the amounts of the above raw materials are calculated by mass percentage as follows: 40% to 45% of polyol, 25% to 30% of silicone oil, 20% to 25% of isocyanate, 0.08%-0.12% of catalyst and 6% to 8% of chain extender; except for the catalyst, the sum of the amounts of the above raw materials is 100%.

[0012] Furthermore, after adding the chain extender, the isocyanate index of the entire reaction system is 0.85-1, preferably 0.9.

[0013] The molecular weight of the polyol is 1000-3000, preferably 1500-2500.

[0014] The organic solvent includes at least one of butanone, toluene, ethyl acetate, N,N-dimethylformamide, tetrahydrofuran and N,N-dimethylacetamide.

[0015] Furthermore, the polyol is polyester polyol, the silicone oil is hydroxy silicone oil, and the chain extender is 1,4-butanediol.

[0016] Furthermore, the prepolymerization reaction and the polymerization reaction are carried out under stirring and reflux.

[0017] Furthermore, the prepolymerization reaction and the polymerization reaction are carried out under the protection of an inert atmosphere.

[0018] The prepolymerization reaction is carried out at a temperature of 70° C. to 80° C. and for a time of 4 h to 8 h.

[0019] Preferably, the prepolymerization reaction time is 5 hours.

[0020] The polymerization reaction temperature is 75° C. to 80° C., and the reaction time is 3 h to 5 h.

[0021] Furthermore, the polyol and the silicone oil are subjected to vacuum dehydration treatment before use, the temperature of the dehydration treatment is 105° C. to 110° C., and after the temperature drops to 60° C., they are added to a reflux device for subsequent preparation.

[0022] Furthermore, the polyether polyol includes polytetramethylene ether glycol and / or polyoxypropylene ether glycol.

[0023] Furthermore, the polyester polyol includes polybutylene adipate diol and / or polyethylene isophthalate diol, preferably polyethylene isophthalate diol.

[0024] Furthermore, the solid content of the silicone-modified polyurethane emulsion is 40% to 60%.

[0025] The second aspect of the present invention provides the use of the organosilicon-modified polyurethane emulsion in a back coating liquid for a thermal transfer carbon ribbon.

[0026] The third aspect of the present invention provides a back coating liquid for a thermal transfer carbon ribbon, comprising an organosilicon-modified polyurethane emulsion and an organic solvent; Wherein, the organosilicon-modified polyurethane emulsion is the organosilicon-modified polyurethane emulsion described in the first aspect.

[0027] Furthermore, in the back coating liquid, the solid content of the back coating liquid is 15% to 25%.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects: The organosilicon-modified polyurethane emulsion provided by the present invention introduces organosilicon molecular chains into the polyurethane system by a solution copolymerization method, and the thermal decomposition temperature of the prepared organosilicon-modified polyurethane is above 350° C. It not only exerts the heat resistance and smoothness of organosilicon, but also exerts the high adhesion between polyurethane and PET film, and combines the advantages of both to meet the needs of thermal transfer.

[0029] The application of the organosilicon-modified polyurethane emulsion provided by the present invention in the back coating liquid provides a better raw material for the back coating liquid for the thermal transfer carbon ribbon, improves the performance of the back coating liquid, ensures the printing quality, and prolongs the service life of the print head.

[0030] The back coating liquid for thermal transfer carbon ribbon provided by the present invention has the advantages of the above-mentioned silicone-modified polyurethane emulsion, so that the back coating liquid has better thermal stability, higher adhesion to PET film and better protection effect on printers. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention described and shown herein can be arranged and designed in various different configurations.

[0032] The first aspect of the present invention provides a silicone-modified polyurethane emulsion, which is mainly obtained by reacting polyol, silicone oil, isocyanate, catalyst and chain extender; The polyols include polyether polyols and / or polyester polyols; The organic silicone oil includes hydroxy silicone oil and / or amino silicone oil; The isocyanate comprises TDI and / or MDI; The catalyst includes dibutyltin dilaurate and / or stannous octoate; The chain extender includes at least one of 1,4-butanediol, 4,4'-methylenebis(2-chloroaniline), diethylene glycol, 1,6-hexanediol and neopentyl glycol. Wherein, isocyanate, catalyst and organic solvent are added to the polyol and the silicone oil to perform prepolymerization reaction to obtain a terminal -NCO group prepolymer, and then the chain extender is added to the prepolymer solution to perform polymerization reaction to obtain the silicone modified polyurethane emulsion.

[0033] The organosilicon-modified polyurethane emulsion provided by the present invention introduces organosilicon molecular chains into the polyurethane system by a solution copolymerization method, and the thermal decomposition temperature of the prepared organosilicon-modified polyurethane is above 350° C. It not only exerts the heat resistance and smoothness of organosilicon, but also exerts the high adhesion between polyurethane and PET film, and combines the advantages of both to meet the needs of thermal transfer.

[0034] Furthermore, the amounts of the above raw materials are calculated by mass percentage as follows: 35% to 50% of polyol, 20% to 32% of silicone oil, 18% to 30% of isocyanate, 0.05%-0.15% of catalyst and 5% to 9% of chain extender; except for the catalyst, the sum of the amounts of the above raw materials is 100%.

[0035] Furthermore, the amounts of the above raw materials are calculated by mass percentage as follows: 40% to 45% of polyol, 25% to 30% of silicone oil, 20% to 25% of isocyanate, 0.08%-0.12% of catalyst and 6% to 8% of chain extender; except for the catalyst, the sum of the amounts of the above raw materials is 100%.

[0036] Typically but not limiting, the amount of polyol used may be, for example, 35%, 37%, 39%, 41%, 43%, 45%, 47%, 49% or 50%, or any value within the range of 35% to 50%.

[0037] When the amount of silicone oil is less than 20%, the decomposition temperature of the prepared silicone-modified polyurethane is lower than 350°C, and the stability is poor; when the amount of silicone oil is higher than 32%, part of the silicone oil does not participate in the reaction, the thermal decomposition temperature is lower than 350°C, and the stability is poor.

[0038] Typically but not limiting, the amount of silicone oil used may be, for example, 20%, 22%, 24%, 26%, 28%, 30% or 32%, or any value within the range of 20% to 32%.

[0039] When the amount of isocyanate is less than 18%, the reaction is not complete, and a large amount of hydroxy silicone oil does not participate in the reaction and is free in the reaction system, resulting in poor heat resistance, smoothness and bonding properties of the material; when the amount of isocyanate is higher than 30%, there are excessive -NCO groups in the prepolymer solution, and it will gel quickly after adding the chain extender, which is difficult to control. Typically but not restrictive, the amount of isocyanate can be, for example, 18%, 20%, 22%, 24%, 26%, 28% or 30%, or any value within the range of 18% to 30%.

[0040] When the amount of chain extender is less than 5%, the chain extension is insufficient, the molecular weight of the obtained organosilicon-modified polyurethane emulsion is low, the adhesion between the coating and the PET film is poor, and the print head is contaminated during printing; when the amount of chain extender is higher than 9%, the reaction is rapid, the viscosity increases sharply, and gelation is easy to occur. Typically but not restrictive, the amount of chain extender can be, for example, 5%, 6%, 7%, 8% or 9%, or any value within the range of 5% to 9%.

[0041] It should be noted that the total mass percentage of the above raw materials is calculated based on the total amount of polyol, silicone oil, isocyanate and chain extender.

[0042] The total amount of catalyst in percent by mass is also calculated based on the total amount of polyol, silicone oil, isocyanate and chain extender.

[0043] Furthermore, after adding the chain extender, the isocyanate index of the entire reaction system is 0.85-1, preferably 0.9.

[0044] When the isocyanate index is lower than 0.85, the reaction is not sufficient, a large amount of hydroxy silicone oil does not participate in the reaction, and is free in the reaction system, resulting in poor heat resistance, smoothness and adhesion of the material; when the isocyanate index is greater than 1, the hard segment content increases, the aggregation ability between the hard segments increases, the phase separation degree between the soft segment and the hard segment increases, and the ability to form hydrogen bonds between the hard segments gradually increases, resulting in a weakened ability to form hydrogen bonds with the PET film, resulting in a decrease in adhesion. At the same time, when the hard segment content increases, too many hard segments make it difficult for the molecular chain to move, which seriously restricts the spreading of the synthetic polymer molecules on the PET surface, reduces the contact area between the synthetic polymer and the PET film to a certain extent, and reduces the density of hydrogen bonds formed between the synthetic polymer and the PET film, thereby reducing adhesion.

[0045] Typically but not limiting, after adding the chain extender, the isocyanate index of the entire reaction system can be, for example, 0.85, 0.9, 0.95 or 1, or any value within the range of 0.85-1.

[0046] The molecular weight of the polyol is 1000-3000, preferably 1500-2500.

[0047] When the molecular weight of the polyol is lower than 1000, the hydroxyl content is high, the reactivity is high, the viscosity rises sharply, and it is easy to gel; when the molecular weight of the polyol is higher than 3000, the hydroxyl content is low, the reactivity is weak, the synthesized silicone-modified polyurethane emulsion has a low molecular weight, the adhesion to the PET film is poor, and the coating is easy to fall off during printing, causing print head pollution. Typically but not restrictive, the molecular weight of the polyol can be, for example, 1000, 1500, 2000, 2500 or 3000, or any value within the range of 1000 to 3000.

[0048] The organic solvent includes at least one of butanone, toluene, ethyl acetate, N,N-dimethylformamide, tetrahydrofuran and N,N-dimethylacetamide.

[0049] Furthermore, the polyol is polyester polyol, the silicone oil is hydroxy silicone oil, and the chain extender is 1,4-butanediol.

[0050] Furthermore, the prepolymerization reaction and the polymerization reaction are carried out under stirring and reflux.

[0051] Furthermore, the prepolymerization reaction and the polymerization reaction are carried out under the protection of an inert atmosphere.

[0052] The prepolymerization reaction is carried out at a temperature of 70° C. to 80° C. and for a time of 4 h to 8 h.

[0053] Typically but not restrictively, the temperature of the prepolymerization reaction can be, for example, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, or any value within the range of 70°C to 80°C; the time of the prepolymerization reaction can be, for example, 4h, 5h, 6h, 7h or 8h, or any value within the range of 4h to 8h.

[0054] Preferably, the prepolymerization reaction time is 5 hours.

[0055] The polymerization reaction temperature is 75° C. to 80° C., and the reaction time is 3 h to 5 h.

[0056] Typically but not limiting, the polymerization reaction temperature can be, for example, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, or any value within the range of 75°C to 80°C; the polymerization reaction time can be, for example, 3h, 4h or 5h, or any value within the range of 3h to 5h.

[0057] Furthermore, the polyol and the silicone oil are subjected to vacuum dehydration treatment before use, the temperature of the dehydration treatment is 105° C. to 110° C., and after the temperature drops to 60° C., they are added to a reflux device for subsequent preparation.

[0058] Furthermore, the polyether polyol includes polytetramethylene ether glycol and / or polyoxypropylene ether glycol.

[0059] Furthermore, the polyester polyol includes polybutylene adipate diol and / or polyethylene isophthalate diol, preferably polyethylene isophthalate diol.

[0060] Furthermore, the solid content of the silicone-modified polyurethane emulsion is 40% to 60%.

[0061] Typically but not limiting, the solid content of the silicone-modified polyurethane emulsion may be, for example, 44%, 48%, 52%, 56% or 60%, or any value within the range of 40% to 60%.

[0062] The second aspect of the present invention provides the use of the organosilicon-modified polyurethane emulsion in a back coating liquid for a thermal transfer carbon ribbon.

[0063] The application of the organosilicon-modified polyurethane emulsion provided by the present invention in the back coating liquid provides a better raw material for the back coating liquid for the thermal transfer carbon ribbon, improves the performance of the back coating liquid, ensures the printing quality, and prolongs the service life of the print head.

[0064] The third aspect of the present invention provides a back coating liquid for a thermal transfer carbon ribbon, comprising an organosilicon-modified polyurethane emulsion and an organic solvent; Wherein, the organosilicon-modified polyurethane emulsion is the organosilicon-modified polyurethane emulsion described in the first aspect.

[0065] The back coating liquid for thermal transfer carbon ribbon provided by the present invention has the advantages of the above-mentioned silicone-modified polyurethane emulsion, so that the back coating liquid has better thermal stability, higher adhesion to PET film and better protection effect on printers.

[0066] Furthermore, the solid content of the back coating liquid is 15% to 25%.

[0067] The solid content of the back coating liquid is adjusted by an organic solvent. The solid content of the back coating liquid may be, for example, 15%, 17%, 19%, 21%, 23% or 25%, or any value within the range of 15% to 25%.

[0068] In the following, some embodiments of the present invention are described in detail in conjunction with the embodiments. In the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. The raw materials used in the present invention can be obtained by commercial purchase unless otherwise specified.

[0069] Example 1 This embodiment provides a silicone-modified polyurethane emulsion, and the specific preparation method is as follows: 1. Dehydrate 43.98% of polyethylene isophthalate glycol (PIA) (molecular weight 2000) and 28% of hydroxy silicone oil (PDMS) at 110°C. After dehydration, reduce the system temperature to 60°C and change to a reflux device. Then add 21.02% of TDI-100, 0.1% of dibutyltin dilaurate and a proper amount of a mixed solvent of butanone and toluene, heat to 75°C under an inert atmosphere, stir and reflux for 5 hours to obtain a terminal-NCO prepolymer solution.

[0070] 2. Add 1,4-butanediol (BDO) at a dosage of 7% to the above prepolymer solution, at which time the isocyanate index R value is 0.9. Continue stirring and refluxing for 4 hours, and the reaction is completed to obtain a silicone-modified polyurethane emulsion with a solid content of 50%.

[0071] Example 2 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Example 1 is that the amount of each raw material is adjusted to 69.13% PIA, 5% hydroxy silicone oil, and 18.87% TDI-100. The remaining raw materials and steps are the same as those in Example 1 and will not be repeated here.

[0072] Example 3 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Example 1 is that the amount of each raw material is adjusted to PIA: 63.68%, hydroxy silicone oil: 10%, TDI-100: 19.32%, and the remaining raw materials and steps are the same as Example 1, which will not be repeated here.

[0073] Example 4 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Example 1 is that the amount of each raw material is adjusted to PIA: 58.22%, hydroxy silicone oil: 15%, TDI-100: 19.78%, and the remaining raw materials and steps are the same as Example 1, which will not be repeated here.

[0074] Example 5 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Example 1 is that the amount of each raw material is adjusted to PIA: 52.77%, hydroxy silicone oil: 20%, TDI-100: 20.23%, and the remaining raw materials and steps are the same as Example 1, which will not be repeated here.

[0075] Example 6 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Example 1 is that the amount of each raw material is adjusted to PIA: 36.41%, hydroxy silicone oil: 35%, TDI-100: 21.59%, and the remaining raw materials and steps are the same as Example 1, which will not be repeated here.

[0076] Example 7 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Example 1 is that the amount of each raw material is adjusted to PIA: 39.68%, hydroxy silicone oil: 32%, TDI-100: 21.32%, and the remaining raw materials and steps are the same as Example 1, which will not be repeated here.

[0077] Example 8 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that after adding BDO, the isocyanate index R value of the system is detected to be 0.7. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described in detail herein.

[0078] Example 9 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that after adding BDO, the isocyanate index R value of the system is detected to be 0.8. The remaining raw materials and steps are the same as those in Embodiment 1 and are not described again.

[0079] Example 10 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that after adding BDO, the isocyanate index R value of the system is detected to be 1.0. The remaining raw materials and steps are the same as those in Embodiment 1 and are not described in detail herein.

[0080] Embodiment 11 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that after adding BDO, the isocyanate index R value of the system is detected to be 1.1. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described in detail.

[0081] Example 12 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that after adding BDO, the isocyanate index R value of the system is detected to be 1.3. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described again.

[0082] Embodiment 13 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that after adding BDO, the isocyanate index R value of the system is detected to be 1.5. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described in detail herein.

[0083] Embodiment 14 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that after adding BDO, the isocyanate index R value of the system is detected to be 0.85. The remaining raw materials and steps are the same as those in Embodiment 1 and are not described again.

[0084] Embodiment 15 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that polytetramethylene glycol (PTMG) is used to replace PIA. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described again.

[0085] Example 16 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that polyoxypropylene ether glycol (PPO) is used to replace PIA. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be repeated here.

[0086] Embodiment 17 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that polybutylene adipate diol (PBA) is used to replace PIA. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be repeated here.

[0087] Embodiment 18 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that the molecular weight of PIA is 650, and the remaining raw materials and steps are the same as those in Embodiment 1, which will not be described again.

[0088] Embodiment 19 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that the molecular weight of PIA is 1000, and the remaining raw materials and steps are the same as those in Embodiment 1, which will not be described again.

[0089] Embodiment 20 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that the molecular weight of PIA is 3000. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described again.

[0090] Embodiment 21 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that the molecular weight of PIA is 1500. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described again.

[0091] Embodiment 22 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that the molecular weight of PIA is 2500. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described again.

[0092] Embodiment 23 This embodiment provides a silicone-modified polyurethane emulsion. The difference from Embodiment 1 is that the molecular weight of PIA is 3500. The remaining raw materials and steps are the same as those in Embodiment 1 and will not be described again.

[0093] Comparative Example 1 This comparative example provides a silicone-modified acrylic resin, model NSA-B20 (Japanese Naituoke).

[0094] Comparative Example 2 This comparative example provides a silicone-modified polyurethane resin, model number SP-809S (Japan Dainippon Seika).

[0095] Test Example 1 The organosilicon-modified polyurethanes obtained in Examples 1 to 7 and the materials in Comparative Examples 1 and 2 were subjected to thermal decomposition temperature tests. The thermal decomposition temperatures were measured by TGA, and the obtained data are shown in Table 1.

[0096] Table 1

[0097] As can be seen from Table 1, with the increase in the amount of hydroxy silicone oil added, the thermal decomposition temperature shows a trend of first increasing and then decreasing. When the amount of hydroxy silicone oil added in Example 1 reaches 28%, the thermal decomposition temperature of the synthetic polymer is the highest and the stability is the best. When the amount of hydroxy silicone oil added in Example 6 reaches 35%, the degree of reaction decreases, part of the hydroxy silicone oil does not participate in the reaction, and the thermal decomposition temperature decreases accordingly. Therefore, the optimal amount of hydroxy silicone oil added in the entire reaction system is 28%.

[0098] Test Example 2 A mixed solvent of butanone and toluene was added to the organosilicon-modified polyurethane emulsions obtained in Example 1 and Examples 8 to 14 and the materials in Comparative Examples 1 and 2, and diluted until the solid content of the emulsions dropped to the test requirements, and used as back coating liquids for thermal transfer ribbons, and then an adhesion test was performed.

[0099] Adhesion test is carried out in two ways. One is to use a hundred-grid method according to GB / T 9286-1988, and the other is to print with a printer and observe the contamination of the print head: 1. Print energy levels from low to high, up to 30. The higher the energy level, the higher the temperature released by the print head instantly. Print speed from 2 to 4 and then to 6. Print multiple media (5 to 7 kinds) and observe the contamination of the print head. 2. Continuous printing at room temperature and continuous printing at high temperature and high humidity (50℃ / 90%): At a certain speed and a certain energy level, print 20,000 sheets continuously on PET label paper and observe the contamination of the print head).

[0100] The obtained data are shown in Tables 2 and 3 below.

[0101] Table 2

[0102] Table 3

[0103] It can be seen from Table 2 and Table 3 that when R>1, the larger the R value, the smaller the adhesion between the coating and the PET film. When the R value increases from 1.0 to 1.5, the adhesion level decreases from 1 to 4.

[0104] As the R value increases, the hard segment content increases, the aggregation ability between the hard segments is enhanced, the phase separation degree between the soft segment and the hard segment increases, and the ability to form hydrogen bonds between the hard segments is gradually enhanced, which leads to the weakening of the ability to form hydrogen bonds with the PET film, and the adhesion decreases. At the same time, when the hard segment content increases, too many hard segments cause difficulty in the movement of the molecular chain, seriously restrict the spreading of the synthetic polymer molecules on the PET surface, reduce the contact area between the synthetic polymer and the PET film to a certain extent, and reduce the density of hydrogen bonds formed between the synthetic polymer and the PET film, so that the adhesion decreases; when R≤1, part of the polyurethane molecular chain is terminated with hydroxyl groups, so that more hydrogen bonds can be formed with the PET film, and the hydrogen bond energy formed by -OH is greater than the hydrogen bond energy formed by -NH, so the adhesion is better. When the R value in Example 1 is 0.9, the adhesion level of the coating and PET is 0, and the print head is pollution-free.

[0105] Test Example 3 A mixed solvent of butanone and toluene was added to the organosilicon-modified polyurethane emulsions obtained in Examples 1 and 15 to 17, and diluted until the solid content of the emulsions dropped to the test requirements, and used as back coating liquids for thermal transfer ribbons, and then an adhesion test was performed according to the method of Test Example 2.

[0106] The obtained data are shown in Tables 4 and 5.

[0107] Table 4

[0108] Table 5

[0109] As shown in Tables 4 and 5, the adhesion of the organosilicon-modified polyurethane coating material synthesized from polyester polyols on PET is better than that of polyether polyols. This is because the main chain of the polyester polyol molecule contains a highly polar ester group, which is easier to form hydrogen bonds with the PET film. In addition, compared with PBA, PIA contains a rigid benzene ring in its structure, which is more polar. At the same time, it is more similar to the structure of PET film, namely polyethylene terephthalate, and it is easier to form hydrogen bonds between the two. Therefore, the adhesion and print head contamination of the organosilicon-modified polyurethane coating material synthesized from PIA are better than those of PBA.

[0110] Test Example 4 A mixed solvent of butanone and toluene was added to the organosilicon-modified polyurethane emulsions obtained in Examples 1 and 18 to 23, and diluted until the solid content of the emulsions dropped to the test requirements, and used as back coating liquids for thermal transfer ribbons, and then an adhesion test was performed according to the method of Test Example 2.

[0111] The obtained data are shown in Tables 6 and 7.

[0112] Table 6

[0113] Table 7

[0114] It can be seen from Tables 6 and 7 that with the increase of PIA molecular weight, the adhesion of the synthetic polymer coating on PET increases. This is because the soft segment molecular weight increases, its flexibility increases, it is more conducive to the regular arrangement of the chain segments, and the degree of crystallization increases; on the other hand, due to the increase of the soft segment molecular weight, the hard segment content decreases, which reduces the hindrance of the hard segment to the soft segment, is conducive to the movement of the molecular chain, and makes it easier for the polyurethane molecules to spread on the PET surface, thereby increasing the density of hydrogen bonds formed between it and the PET film, so the adhesion increases. When the molecular weight increases to more than 3000g / mol, the hydroxyl content is low, the reaction activity is weak, the molecular weight of the synthesized silicone-modified polyurethane emulsion is low, and the adhesion to the PET film is poor. The coating is easy to fall off during printing, causing print head pollution.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicone-modified polyurethane emulsion, characterized in that: It is mainly obtained by the reaction of polyol, silicone oil, isocyanate, catalyst and chain extender; The polyols include polyether polyols and / or polyester polyols; The organic silicone oil includes hydroxy silicone oil and / or amino silicone oil; The isocyanate comprises TDI and / or MDI; The catalyst includes dibutyltin dilaurate and / or stannous octoate; The chain extender includes at least one of 1,4-butanediol, 4,4'-methylenebis(2-chloroaniline), diethylene glycol, 1,6-hexanediol and neopentyl glycol; Wherein, isocyanate, catalyst and organic solvent are added to the polyol and the silicone oil to carry out prepolymerization reaction to obtain a prepolymer solution with terminal -NCO groups, and then the chain extender is added to the prepolymer solution to carry out polymerization reaction to obtain the silicone-modified polyurethane emulsion.

2. The organosilicon-modified polyurethane emulsion according to claim 1, characterized in that: Calculated by mass percentage, polyol 35%~50%, silicone oil 20%~32%, isocyanate 18%~30%, catalyst 0.05%-0.15% and chain extender 5%~9%; except for the catalyst, the sum of the amounts of the above raw materials is 100%.

3. The organosilicon-modified polyurethane emulsion according to claim 1, characterized in that: Calculated by mass percentage, polyol 40%~45%, silicone oil 25%~30%, isocyanate 20%~25%, catalyst 0.08%-0.12% and chain extender 6%~8%; except for the catalyst, the sum of the amounts of the above raw materials is 100%.

4. The organosilicon-modified polyurethane emulsion according to claim 1, characterized in that: After adding the chain extender, the isocyanate index of the entire reaction system is 0.85~1; The molecular weight of the polyol is 1000-3000; The organic solvent includes at least one of butanone, toluene, ethyl acetate, N,N-dimethylformamide, tetrahydrofuran and N,N-dimethylacetamide.

5. The organosilicon-modified polyurethane emulsion according to any one of claims 1 to 4, characterized in that: The prepolymerization reaction and the polymerization reaction are carried out under stirring and reflux; The prepolymerization reaction temperature is 70°C to 80°C and the reaction time is 4h to 8h; The polymerization reaction temperature is 75° C. to 80° C., and the reaction time is 3 h to 5 h.

6. The organosilicon-modified polyurethane emulsion according to any one of claims 1 to 4, characterized in that: The polyether polyol includes polytetramethylene ether glycol and / or polyoxypropylene ether glycol; The polyester polyol includes polybutylene adipate diol and / or polyethylene isophthalate diol.

7. The organosilicon-modified polyurethane emulsion according to any one of claims 1 to 4, characterized in that: The solid content is 40%~60%.

8. Use of the organosilicon-modified polyurethane emulsion according to any one of claims 1 to 7 in a back coating liquid for a thermal transfer ribbon.

9. A back coating liquid for thermal transfer carbon ribbon, characterized in that: Including silicone modified polyurethane emulsion and organic solvent; Wherein, the organosilicon-modified polyurethane emulsion is the organosilicon-modified polyurethane emulsion according to any one of claims 1 to 7.

10. The back coating liquid for thermal transfer carbon ribbon according to claim 9, characterized in that: The solid content of the back coating liquid is 15% to 25%.

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