CN104788987B - Chain tra nsfer nir dye and its high molecular polymerization emulsion preparation method and application - Google Patents

Abstract

A kind of chain tra nsfer nir dye and its high molecular polymerization emulsion preparation method and application.This can the nir dye of chain tra nsfer be to react to be obtained by nir dye and difunctional sulfydryl, by nir dye, chain tra nsfer functionalized reagent, accelerator according to mol ratio 1:1‑20:14 are mixed in organic solvent and are reacted, and dyestuff is 1g with solvent load ratio:10ml‑50ml；In the reactions steps, temperature is 0 50 DEG C；Time is 10 72 hours；Reaction terminate after by product ether separating, washing, 8,000 12000 revs/min of high speed centrifugations, collection obtain it is described can chain tra nsfer nir dye.It can occur chain transfer reaction in emulsion polymerization process, so as to producing high-molecular thermally sensitized polymerization emulsion is obtained.Gained producing high-molecular thermally sensitized polymerization emulsion not only increases the stability of nir dye, is applied in infrared laser imaging field at the same time as heat-sensitive precursor.

Description

Preparation method and application of chain transfer near-infrared dye and polymer emulsion thereof

technical field

The invention relates to the technical fields of fine chemical industry and material chemistry, in particular to a chain-transfer near-infrared dye and a preparation method and application of a polymer emulsion thereof.

Background technique

The lithographic printing plate is characterized by the graphic part and the blank part, there is no obvious difference in height, and they are almost on the same plane. Its function is to transfer the printing ink loaded by the graphic part to the substrate under the printing pressure, while the other part does not transfer the printing ink to form a non-graphic part. The plate-making process of lithographic printing plate is that after the printing plate is selectively exposed, the photosensitive coating undergoes photophysical and chemical changes to form an image, and a printable graphic part is obtained. Among them, the heat-sensitive plate is exposed by near-infrared laser, and the graphic part is obtained by developing.

According to the imaging principle of the heat-sensitive plate, the photosensitive layer of the plate is also called the printing plate precursor, which is mainly composed of heat-sensitive near-infrared dyes, film-forming resins and corresponding additives. It is a series of photophysical and chemical changes that occur after the near-infrared dye absorbs the near-infrared laser, so that the film-forming resin has a certain solubility change in the alkali solvent, and the corresponding printing plate is made by using the alkali solvent for development, which is As a result, a large amount of chemical reagents will be used in the plate-making process of thermal printing plates. At present, with the emphasis on environmental protection in various countries, it is the goal pursued by the printing industry in recent years to obtain chemical-free thermal imaging materials by using water as a developer. Emulsion polymerization technology is an environmentally friendly polymerization technology among polymerization methods. The biggest advantage is (1) it uses water as the dispersion medium, which is safe and environmentally friendly; (2) it can be used directly in the form of emulsion. Using emulsion polymerization technology, imaging based on the principle of thermal phase change of thermoplastic nano-microsphere emulsion before and after exposure has become a hot spot in the development of chemical-free thermosensitive imaging materials. For example, European patents EP-770494, 770495, 770497 and other patents report that after the exposure of the plate precursor composed of thermoplastic particles, the particles undergo a thermal phase change, thereby obtaining the graphic part and realizing the heat treatment without chemical treatment. Sensitive plate. European patents EP 1 736 312 and 1 910 082 provide another lithographic precursor, which contains infrared absorbing dyes and thermoplastic microspheres. In this way, the graphic part is formed, and the printing plate is obtained after development.

In the above system construction, the precursors of heat-sensitive materials are all prepared by emulsion polymerization to form thermoplastic particles and adding infrared absorbing dyes. However, this system has many problems:

First, infrared dyes are oil-soluble dyes. When they are compounded with water-based dispersed emulsions, there are compatibility problems, which will lead to uneven and unstable dispersion of infrared dyes in the water system.

Second, after the product is formed into a film, the infrared dye will migrate in the printing plate precursor due to compatibility problems, resulting in uneven dispersion of the dye in the printing plate precursor film, resulting in unstable imaging.

Third, the infrared absorbing dye and nanoparticles are separated in the system, and the photostability of the dye is poor, so that the printing plate has a certain amount of fog before exposure, and the contrast of the final product is reduced.

In view of the above problems, polymerizing the dye provides the possibility to solve the above problems. At home and abroad, there are also certain reports on the polymerization of dyes. Kan Chengyou and others modified the dyes into polymerizable monomers in Chinese patent CN103205139A, and realized the polymerization of dyes in emulsion polymerization; Zhao Zhengguo in Chinese patent CN103159904A The dye is grafted into the polymer compound to realize the polymerization of the dye; Konstantinova et al. (Dyes and Pigments, 1989,10(1):63-67) studied the addition polymerization of styrene and some fused ring aromatic hydrocarbon derivative dyes reaction. At present, there is no report on the construction of thermosensitive emulsion precursor by polymerizing infrared absorbing dyes by chain transfer reaction.

Contents of the invention

In order to solve the problems in the above-mentioned prior art, the object of the present invention is to provide a method for preparing a chain-transferable near-infrared dye and a polymer heat-sensitive polymerization emulsion thereof. It is prepared by the reaction of difunctional mercapto groups, and can undergo chain transfer reaction with free radicals of the polymer chain during the emulsion polymerization process, so as to obtain high-molecular heat-sensitive polymer emulsion. The obtained polymerized heat-sensitive polymer emulsion not only improves the stability of the near-infrared dye, but also can be used as a heat-sensitive precursor in the field of infrared laser imaging.

To achieve the above object, the technical solution of the present invention is:

A chain-transferred near-infrared dye, the method for preparing a chain-transferable near-infrared dye, the specific steps are as follows: mix a near-infrared dye, a chain transfer functional reagent, and an accelerator in an organic solvent for reaction, and obtain the obtained Chain-transferable near-infrared dyes.

In the above method, the near-infrared dye is selected from a cyanine dye compound, specifically a cyanine dye from a cyanine dye, and the optimal absorption spectrum wavelength of a near-infrared absorbing dye is at a near-infrared wavelength of 700nm-1100nm. The preferred chemical structural formula of the infrared absorbing dye is as follows, and its general structural formula is as follows:

Wherein R ₁ is selected from Cl;

R ₂ is selected from alkyl, aralkyl or aryl.

X is selected from ClO ₄ , I, Br, p-toluenesulfonic acid.

The chain transfer functionalization reagent is selected from 1,2-ethanedithiol, 1,6-hexanedithiol, 1,3-propanedithiol, 2,3-butanedithiol, 1,10-decane Dithiol, 1,4-Benzyldimethylthiol, m-Dibenzylthiol, Pentaerythritol Tetrakis(3-Mercaptopropionate), 4,4'-thiobisthiol, 2,3 Dimercaptobutane At least one of acid and thiodiglycol mercaptan.

The accelerator is selected from at least one of inorganic bases and organic bases, specifically selected from at least one of sodium carbonate, sodium hydroxide and triethylamine.

The organic solvent is selected from at least one of N,N-dimethylformamide, methanol, ethanol, chloroform or dimethyl sulfoxide.

The molar ratio of the near-infrared dye, the chain transfer functional reagent, and the accelerator is 1:1-20:1-4, specifically 1:1-10:1-3, more specifically 1:5:1, 1: 10:2, 1:5:1.5, 1:10:3, or 1:7:2.

The dosage ratio of the dye to the solvent is 1g:10ml-50ml, specifically 1g:10-30ml.

In the substitution reaction step, the temperature is 0-50°C, specifically 10-35°C. The time is 10-72 hours, specifically 12-48 hours.

The method may further include the following steps: after the substitution reaction step, the reaction product is separated and washed with ether, centrifuged at a high speed, and the chain-transferable near-infrared dye is collected.

The preparation of the chain-transferable near-infrared dye and its polymerized heat-sensitive polymer emulsion prepared according to the above method also belongs to the protection scope of the present invention.

Wherein, the chain-transferable near-infrared dye is specifically:

The above chain-transferable near-infrared dyes are obtained by modifying near-infrared dyes with bis- and polymercapto compounds. Since the near-infrared dye molecule has a maximum absorption wavelength in the near-infrared region and has a mercapto functional group, it can act as a chain transfer agent in the polymerization process to obtain a polymerized near-infrared absorbing dye. Therefore, the present invention also provides a method for preparing a polymerized heat-sensitive emulsion based on the above-mentioned near-infrared dye, comprising the following steps: mixing monomers, chain-transferable near-infrared dyes, emulsifiers, co-emulsifiers, initiators It is mixed with water to perform emulsion copolymerization reaction, and the polymerized near-infrared dye heat-sensitive polymerization emulsion is obtained after the reaction is completed.

The mixed monomers are styrene, vinyl chloride, methyl methacrylate, butyl methacrylate, methacrylic acid, acrylic acid, hydroxypropyl methacrylate, vinylidene chloride, acrylonitrile, methacrylonitrile , N-phenylmaleimide, a monomer homopolymer of glycidyl methacrylate or a copolymer of several monomers.

The emulsifier is at least one selected from nonionic surfactants and anionic surfactants. Wherein the anionic surfactant is alkyl sulfate, alkyl ether sulfate, alkyl ether carboxylate, alkyl or aryl sulfonate, alkyl phosphate or alkyl ether phosphate, reactive group Group of anionic or nonionic emulsifiers. Specific chemical structure names, such as: sodium lauryl sulfate, sodium lauryl sulfate, sodium oleate, sodium dodecylbenzenesulfonate, sodium laureth sulfate, lauryl polyether carboxylate, tridecyl Alkanol polyether phosphate, etc. The preferred structural formula of the anionic emulsifier of the reactive group is as follows:

wherein X is selected from SO ₃ NH ₄ , SO ₃ Na or SO ₃ K;

Nonionic emulsifier, preferred structure is as follows:

Wherein R is selected from methyl, phenyl or isopropyl, and its number average molecular weight is 400-5000.

The co-emulsifier can be one of n-butanol, ethylene glycol, ethanol, propylene glycol, glycerin, cetyl alcohol and other compounds used alone or in combination.

The preparation method of the above-mentioned polymerized heat-sensitive emulsion is a miniemulsion copolymerization method well known in the art, which is prepared by a method of initiating emulsion polymerization by a redox system, and the percentages mentioned below are all mass percentages.

Step 1. Prepare the oil phase, dissolve 1-10% chain-transferable near-infrared dyes and 10-40% monomers evenly and add them into the reaction bottle;

Step 2, water phase preparation, will include: deionized water 50-90%, emulsifier 1-10%, co-emulsifier 0.1-2% into the reaction bottle, and then add a concentration of 5-10% water-soluble initiator 1-5% of the reducing agent solution in the mixture, and stir evenly to obtain a mixed solution;

Step 3. After mixing the water phase and the oil phase prepared in Step 1 and Step 2 evenly, stir under the homogenizer for 5-10 minutes to obtain a pre-emulsified mixture;

Step 4. After emulsifying with mechanical stirring for 20 minutes at 30°C, add 1-5% of an aqueous solution containing an oxidant at a concentration of 5-10% to initiate a polymerization reaction; the reaction continues for 3-10 hours until the monomer conversion rate is greater than 70% , the additional concentration is 1-5% of the reducing agent solution in the 5-10% water-soluble initiator and the concentration is 1-5% of the reducing agent solution in the 5-10% water-soluble initiator, and the reaction is continued for 3-5 hours A stable polymer emulsion containing an infrared absorbing dye is obtained.

The oxidant in the initiator can be potassium persulfate, sodium persulfate, p-menthane hydrogen peroxide, hydrogen peroxide or tert-butyl hydroperoxide. The corresponding reducing agent is ferrous sulfate, diacid block, hydrazine hydrate, adipic hydrazide or vitamin C.

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

The invention provides a chain-transferred infrared absorbing dye and a method for preparing a polymerized heat-sensitive polymer emulsion. The invention uses a cheap and easy-to-obtain 830nm near-infrared dye that is widely used in the market, and obtains a dye with a mercapto group through one-step modification. The near-infrared dye that can be chain-transferred enables the dye to undergo a chain-transfer reaction during the polymerization process, thereby making the dye polymerized and improving the stability of the near-infrared dye; the polymerized infrared dye has a maximum absorption wavelength near 830nm. After the prepared emulsion is coated and exposed to infrared laser, the polymer microspheres can undergo a thermal phase change, which provides a source of heat-sensitive precursor for the chemical-free printing plate to realize water development.

Description of drawings

Figure 1 is the NMR image of the near-infrared dye raw material IR-830 used.

Fig. 2 is the NMR image of the chain-transferable infrared dye of Example 1.

Fig. 3 is the NMR image of the chain-transferable infrared dye of Example 2.

Fig. 4 is the NMR image of the chain-transferable infrared dye of Example 3.

Fig. 5 is the NMR image of the chain-transferable infrared dye of Example 4.

Fig. 6 is the NMR image of the chain-transferable infrared dye of Example 5.

Figure 7 is a graph comparing the molecular weight of emulsion polymerization (GPC) in the absence and presence of the chain transferable infrared dye of Example 1.

Figure 8 is the UV-visible spectrum of raw material IR-830 under visible light for 8 hours and 24 hours for photostability test.

Figure 9 is the ultraviolet-visible spectrum of the photostability test for 8 hours and 24 hours under visible light after polymerizing the polymerized emulsion of Example 1.

Fig. 10 is a scanning electron microscope image of polymer microspheres composed of infrared dyes after macromolecularization undergoing a thermal phase change under 830nm infrared laser exposure.

Fig. 11 is a clear image obtained by washing with water after exposure of polymer microspheres composed of polymerized infrared dyes.

Figure 12 Chemical structure diagram of reactive emulsifier.

detailed description

The technical scheme of the present invention is described in further detail below in conjunction with specific embodiments:

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials and reagents used in the following examples can be obtained from commercial sources unless otherwise specified.

As shown in Fig. 1 is the NMR image of the near-infrared dye principle IR-830 used in the present invention.

Example 1 Synthesis of near-infrared dyes using 1,6-hexanedithiol as chain transfer reagent and preparation of polymerized heat-sensitive polymer emulsion

(1) Preparation of thermosensitive near-infrared dyes capable of chain transfer

Add 6 grams of near-infrared dye, 5.96 grams of 1,6-hexanedithiol and 4 grams of triethylamine into a single-port bottle, wherein, near-infrared dye: 1,6-hexanedithiol: triethylamine (molar ratio) 1 :5:5, add 50 ml of N,N dimethylformamide, stir and mix and react at 25°C under nitrogen protection for 24 hours. Centrifuge at a speed of 1/min and collect the solid dye after drying.

As shown in Figure 2 is the NMR diagram of the chain transferable infrared dye of Example 1.

The reaction equation of above-mentioned preparation dye monomer is as follows:

(2) Preparation of polymerized thermosensitive polymer emulsion

The oil phase is prepared by dissolving 5 grams of the above-mentioned near-infrared absorbing dye, 18.75 grams of styrene and 6.25 grams of acrylonitrile into the reaction bottle, and mixing uniformly;

Prepare the water phase by adding: 50 grams of water, 0.75 grams of sodium lauryl sulfate, 0.2 grams of cetyl alcohol and tert-butyl hydroperoxide with a mass fraction of 0.15 grams into the reaction flask, and stir evenly to obtain a mixed solution;

After the water phase and the oil phase prepared in the above two steps are uniformly mixed, they are stirred under a homogenizer for 8 minutes to obtain a pre-emulsified mixture.

Finally, at 30°C, after emulsifying with mechanical stirring for 20 minutes, 10 g of an aqueous solution containing 0.1 g of ferrous sulfate was added to the mixed liquid to initiate a polymerization reaction. The reaction continued for 10 hours until the monomer conversion rate was greater than 70%, and then the same amount of ferrous sulfate solution and tert-butyl hydroperoxide solution were added successively to continue the reaction for 4 hours to obtain a stable polymerized thermosensitive polymer emulsion.

Figure 7 is a comparison chart of emulsion polymerization molecular weight (GPC) in the absence and presence of the chain-transferable infrared dye of Example 1.

As shown in Figure 8, the UV-visible spectrum of the raw material IR-830 was tested for light stability under visible light for 8 hours and 24 hours.

As shown in Figure 9, the ultraviolet-visible spectrum of the polymerized emulsion in Example 1 was tested for light stability under visible light for 8 hours and 24 hours.

As shown in Figure 10, the scanning electron micrograph of the thermal phase change of the polymer microspheres composed of infrared dyes after polymerization is exposed to 830nm infrared laser.

The clear image obtained by washing with water after exposure is shown in Figure 11.

Example 2 Synthesis of near-infrared dyes using 1,2-ethanedithiol as a chain transfer agent and preparation of polymerized thermosensitive polymer emulsion

(1) Preparation of thermosensitive near-infrared dyes capable of chain transfer

Add 6 grams of near-infrared dye, 7.47 grams of 1,2-hexanedithiol and 8 grams of triethylamine into a single-port bottle, wherein, near-infrared dye: 1,2-ethanedithiol: triethylamine (molar ratio) 1 :10:10, add 50 milliliters of N,N dimethylformamide, stir and mix and react for 12 hours under nitrogen protection at 25°C, after the end, add a large amount of ether to the flask for stirring and washing. Centrifuge at a speed of 1/min and collect the solid dye after drying.

As shown in Figure 3 is the NMR image of the chain transferable infrared dye of Example 2.

The reaction equation of above-mentioned preparation dye monomer is as follows:

(2) Preparation of polymerized thermosensitive polymer emulsion

The oil phase is prepared by dissolving 4 grams of the above-mentioned near-infrared absorbing dye, 20 grams of styrene and 5 grams of acrylonitrile into the reaction bottle, and mixing evenly;

Prepare the water phase by adding: 50 grams of water, 0.6 grams of sodium lauryl sulfate, 0.1 grams of hexadecane and 0.12 grams of tert-butyl hydroperoxide in the reaction flask, and stir evenly to obtain a mixed solution;

After the water phase and the oil phase prepared in the above two steps are uniformly mixed, they are stirred under a homogenizer for 10 minutes to obtain a pre-emulsified mixed liquid.

Finally, at 30° C., after emulsifying with mechanical stirring for 20 minutes, 10 g of an aqueous solution containing 0.15 g of vitamin C was added to the mixed liquid to initiate a polymerization reaction. The reaction continued for 8 hours until the monomer conversion rate was greater than 70%, and then the same amount of vitamin C solution and tert-butyl hydroperoxide solution were added successively to continue the reaction for 4 hours to obtain a stable polymerized thermosensitive polymer emulsion.

Example 3 Synthesis of near-infrared dyes using 2,3 dimercaptosuccinic acid as chain transfer reagent and preparation of polymerized heat-sensitive polymer emulsion

(1) Preparation of thermosensitive near-infrared dyes capable of chain transfer

Add 6 grams of near-infrared dye, 2.15 grams of 2,3 dimercaptosuccinic acid and 0.6 grams of triethylamine into a one-mouth bottle, wherein, near-infrared dye: 2,3 dimercaptosuccinic acid: triethylamine (molar ratio) 1:1.5:1.5, add 50 ml of N,N dimethylformamide, stir and mix and react at 25°C under nitrogen protection for 24 hours. Centrifuge at a speed of 1 rpm, and collect the solid dye after drying.

As shown in FIG. 4 is the NMR image of the chain-transferable infrared dye of Example 3.

The reaction equation of above-mentioned preparation dye monomer is as follows:

(2) Preparation of polymerized thermosensitive polymer emulsion

Prepare the oil phase, dissolve 3 grams of the above-mentioned infrared absorbing dye, 20 grams of styrene and 10 grams of hydroxypropyl methacrylate into the reaction bottle, and mix well;

Prepare the water phase by adding: 57 grams of water, 2% reactive emulsifier (structure shown in Figure 12), 0.15 grams of cetyl alcohol and 0.15 grams of tert-butyl hydroperoxide into the reaction flask, and stir evenly to obtain a mixed solution;

After the water phase and the oil phase prepared in the above two steps are uniformly mixed, they are stirred under a homogenizer for 5 minutes to obtain a pre-emulsified mixture.

Finally, at 30° C., after mechanical stirring and emulsification for 20 minutes, 10 grams of an aqueous solution of sodium thiosulfate containing 0.15 grams was added to the reaction bottle to initiate a polymerization reaction. The reaction continued for 10 hours until the monomer conversion rate was greater than 70%, and then the same amount of tert-butyl hydroperoxide aqueous solution and sodium thiosulfate aqueous solution were added successively to continue the reaction for 5 hours, and a stable polymer containing infrared absorbing dye was obtained lotion.

Example 4 Synthesis of near-infrared dyes using 4,4'-thiobisthiophenol as chain transfer reagent and preparation of polymerized thermosensitive polymer emulsion

(1) Preparation of thermosensitive near-infrared dyes capable of chain transfer

Add 6 g of near-infrared dye, 1.97 g of 4,4'-thiobisthiol and 0.8 g of triethylamine into a single-mouth bottle, wherein, near-infrared dye: 4,4'-thiobisthiol: three Ethylamine (molar ratio) 1:1:1, add 50 ml of N,N dimethylformamide, stir and mix and react at 25°C under nitrogen protection for 16 hours, add a large amount of ether to the flask after stirring and washing, Centrifuge at a speed of 10,000 rpm in a high-speed centrifuge, and collect the solid dye after drying. As shown in Figure 5 is the chain transfer infrared dye NMR figure of example 4

The reaction equation of above-mentioned preparation dye monomer is as follows:

(2) Preparation of polymerized thermosensitive polymer emulsion

The oil phase is prepared by dissolving 4.5 grams of the above-mentioned infrared absorbing dye, 20 grams of styrene and 10 grams of acrylonitrile into the reaction bottle, and mixing evenly;

Water phase preparation, including: 55.5 grams of water, 0.8 grams of sodium lauryl sulfate, 0.2 grams of cetyl alcohol and 0.15 grams of tert-butyl hydroperoxide were added to the reaction flask, and stirred evenly to obtain a mixed solution;

After the water phase and the oil phase prepared in the above two steps are uniformly mixed, they are stirred under a homogenizer for 5 minutes to obtain a pre-emulsified mixture.

Finally, at 30° C., after mechanical stirring and emulsification for 20 minutes, 10 grams of vitamin C solution containing 0.15 grams was added to the reaction flask to initiate polymerization. The reaction continued for 10 hours until the monomer conversion rate was greater than 70%, and then the same amount of tert-butyl hydroperoxide aqueous solution and vitamin C aqueous solution were added successively to continue the reaction for 5 hours, and a stable polymer emulsion containing infrared absorbing dye was obtained.

Example 5 Synthesis of near-infrared dyes using thiodiglycol as chain transfer agent and preparation of polymerized heat-sensitive polymer emulsion

(1) Preparation of thermosensitive near-infrared dyes capable of chain transfer

Add 6 grams of near-infrared dye, 4.96 grams of thiodiglycol mercaptan and 4 grams of triethylamine into the one-mouth bottle, wherein, near-infrared dye: thiodiglycol mercaptan: triethylamine (molar ratio) 1:5:5 , add 50 ml of N,N dimethylformamide, stir and mix and react at 25°C under nitrogen protection for 24 hours. After the end, add a large amount of ether to the flask for stirring and washing. The solid dye was collected by centrifugation and dried.

As shown in FIG. 6 is the NMR image of the chain-transferable infrared dye of Example 5.

The reaction equation of above-mentioned preparation dye monomer is as follows:

(2) Preparation of polymerized thermosensitive polymer emulsion

The oil phase is prepared by dissolving 3 grams of the above-mentioned infrared absorbing dye, 20 grams of styrene and 10 grams of acrylonitrile into the reaction bottle, and mixing evenly;

Water phase preparation, including: 57 grams of water, 0.8 grams of sodium lauryl sulfate, 0.2 grams of cetyl alcohol and 0.15 grams of tert-butyl hydroperoxide were added to the reaction flask, and stirred evenly to obtain a mixed solution;

After the water phase and the oil phase prepared in the above two steps are uniformly mixed, they are stirred under a homogenizer for 5 minutes to obtain a pre-emulsified mixture.

Finally, at 30° C., after mechanical stirring and emulsification for 20 minutes, 10 grams of vitamin C solution containing 0.15 grams was added to the reaction flask to initiate polymerization. The reaction continued for 10 hours until the monomer conversion rate was greater than 70%, and then the same amount of tert-butyl hydrogen peroxide aqueous solution and vitamin C aqueous solution were added successively to continue the reaction for 5 hours, and a stable polymer emulsion containing infrared absorbing dye was obtained.

The above is only a specific implementation of the present invention, but the scope of protection of the present invention is not limited thereto, and any changes or replacements that do not come to mind through creative work shall be covered within the scope of protection of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope defined in the claims.

Claims (3)

1. a method for preparing near-infrared dyes of chain transfer, is characterized in that, comprises the steps: Near-infrared dyes, chain transfer functionalization reagents, and accelerators are mixed in organic solvents according to a molar ratio of 1:1-20:1-4 for reaction, and the dye and solvent dosage ratio is 1g:10mL-50mL; In the reaction step, the temperature is 0-50°C; the time is 10-72 hours; After the reaction, the reaction product is separated and washed with ether, centrifuged at 8000-12000 rpm at a high speed, and the chain-transferable near-infrared dye is collected, and the near-infrared dye is selected from methine cyanine dye compounds; the accelerator is selected from At least one of inorganic bases or organic bases; The near-infrared dye is selected from the cyanine dyes of Qijiachuan, and the optimum absorption spectrum wavelength of the near-infrared absorbing dye is 700nm-1100nm near-infrared wavelength; its general structural formula is as follows: Wherein R ₁ is selected from Cl; R is selected from alkyl, aralkyl or aryl _; X is selected from ClO ₄ , I, Br, p-toluenesulfonic acid; The organic solvent is at least one selected from N,N dimethylformamide, methanol, ethanol, chloroform or dimethyl sulfoxide. 2. The method according to claim 1, wherein the chain transfer functionalization reagent is selected from 1,2-ethanedithiol, 1,6-hexanedithiol, 1,3-propanedithiol , 2,3-butanedithiol, 1,10-decanedithiol, 1,4-benzenedimethanol, m-dibenzylmercaptan, pentaerythritol tetraester, 4,4'-thiobisthiol , 2,3 dimercaptosuccinic acid, and at least one of thiodiglycol mercaptan. 3. according to the arbitrary described method of claim 1-2, it is characterized in that, the near-infrared dye that the chain transfer that prepares is specifically: ;