CN114524921A - Biodegradable high-molecular photoinitiator and preparation and application thereof - Google Patents

Abstract

The invention relates to a biodegradable polymer photoinitiator and its preparation and application. The structure of the photoinitiator is shown in formula I. The polymer photoinitiator of the invention retains the photoinitiating activity of the small molecule photoinitiator, avoids the safety problems such as volatile organic gas and migration when the ordinary photoinitiator is used, and has biodegradability, which can be passed through biological Degradation reduces the pollution to the environment, and can be widely used in the fields of photocurable coatings, inks, adhesives and photocrosslinking. The preparation method provided by the invention has the advantages of simple process, high efficiency, rapidity, easy industrialization and the like.

Description

A kind of biodegradable polymer photoinitiator and its preparation and application

technical field

The invention belongs to the technical field of functional polymers, and in particular relates to a biodegradable polymer photoinitiator and its preparation and application.

Background technique

Ultraviolet light curing technology refers to a photoprocessing process in which the resin matrix is rapidly cross-linked by the excitation of the photoinitiator through the irradiation of ultraviolet light of a certain wavelength. The advantages of light curing technology are fast reaction rate, short processing cycle, high efficiency, energy saving, environmental protection, and cost saving. At present, UV curing technology has been widely used in the fields of photocurable coatings, inks, adhesives and photocrosslinking.

The photoinitiator is a key part of the photocuring system. Photoinitiators refer to substances that can generate reactive intermediates (free radicals or ions) that initiate polymerization and cross-linking of multifunctional monomers, oligomers or polymer matrices under irradiation of a certain wavelength. Under the irradiation of ultraviolet light or visible light of a certain wavelength, the photoinitiator molecule absorbs light energy, transitions from the ground state to the excited state, and generates active species after the excited state undergoes monomolecular or bimolecular chemical action, thereby triggering monomer, oligomerization The reaction of the polymer or polymer matrix to form a cross-linked network structure.

According to different excitation wavelengths, photoinitiators can be divided into ultraviolet photoinitiators (200-400nm in the ultraviolet region) and visible light initiators (400-700nm in the visible region). At present, the light curing technology is mainly ultraviolet light curing, and the photoinitiator used is an ultraviolet photoinitiator. Visible light initiators are limited in production and use due to their sensitivity to sunlight and lighting sources. In recent years, with the wide application of photocuring technology, more types of photoinitiators have been developed, such as water-soluble photoinitiators, hybrid photoinitiators, macromolecular photoinitiators, etc.

Traditional photoinitiators are mainly small molecular photoinitiators. Photoinitiators can be mainly divided into two types according to the type of reaction, namely free radical photoinitiators and ionic photoinitiators. Among them, free radical photoinitiators can be further divided into cracking free radical photoinitiators (Norrish I type) and hydrogen abstraction free radical photoinitiators (Norrish II type). Cleavage-type free radical photoinitiator is the α bond cleavage after the initiator absorbs light energy, and the homolytic cleavage forms two pairs of carbon-carbon double bonds with reactive free radicals. Most Norrish I photoinitiators are aromatic carbonyl compounds with appropriate substituents, such as benzoin and its derivatives, benzil ketals, and acylphosphine oxides. Norrish type II photoinitiator is that after the initiator absorbs light energy, bimolecular interaction with co-initiator occurs in the excited state, and forms active radicals through hydrogen abstraction reaction or electron/proton transfer. This photoinitiator is based on triplet excited state. Reacts with a hydrogen donor to generate initiating free radicals. Since the Norrish type II photoinitiator is a bimolecular radical generating process, the reaction rate is slower than that of the Norrish type I photoinitiator, which forms a free radical from a single molecule. Typical Norrish type II photoinitiators include benzophenone and its derivatives, thioxanthone, benzil or quinones and the like.

However, on the one hand, these small molecule photoinitiators are easy to produce small molecule volatiles during the photocuring process, which leads to the emission of VOC and the generation of peculiar smell; Safety or surface quality of the product. In response to these situations, IGM of the Netherlands has developed the Omnipol series of macromolecular photoinitiators. Specifically, by making the photoinitiator macromolecular, it can effectively reduce the generation and migration of photocuring volatiles, and at the same time improve the initiating activity and improve the performance of the matrix resin. However, its molecular weight is generally below 1000, which is not a macromolecule in the true sense, so it cannot completely solve the problem of causing residue volatilization and migration. The domestic Beijing University of Chemical Technology has also disclosed a series of macromolecular photoinitiators: Chinese patents CN201910265332.5 and CN201910265343.3 disclose macromolecular photoinitiators obtained by aldehyde-ketone condensation reaction and their preparation methods; Chinese patents CN201910265507.2 and CN201910265508. 7 discloses a hydrogen donor nitrogen-containing macromolecular initiator obtained by free-radical copolymerization; Chinese patents CN201210012986.5 and CN201110355051.2 disclose that hydroxybenzophenone and formaldehyde are polymerized to prepare macromolecules with red-shifted ultraviolet absorption photoinitiator.

However, these macromolecular initiators have problems such as uncontrollable chemical structure, uncontrollable molecular weight or low content of initiating groups. Moreover, these macromolecular photoinitiators, especially benzophenone photoinitiators, almost all of their initiating groups are in the side chain, and there are still a large proportion of photolysis residues that will volatilize and migrate, which cannot completely overcome the small Problems with molecular photoinitiators. In addition, the existing commonly used small molecular photoinitiators and macromolecular photoinitiators generally have low thermal stability, and their thermal decomposition temperature is basically lower than 250 ° C (for example, the thermal decomposition temperature of the most commonly used photoinitiator benzophenone is 160 °C). ℃), which limits the application of the above-mentioned photoinitiators in the crosslinking modification processing of engineering plastics.

On the other hand, with the increasingly serious problem of environmental pollution, biodegradation has attracted more and more attention. At present, most biodegradable materials are aliphatic polyesters, but the poor heat resistance and processing properties of aliphatic polyesters limit their applications in various fields. In recent years, in order to achieve the purpose of obtaining polymers with thermal properties and processing properties that can meet processing requirements, researchers have carried out research on the synthesis of copolyesters combining aromatic and aliphatic units. Taking this as a starting point, for the problems existing in the above-mentioned existing photoinitiators, the preparation of a macromolecular photoinitiator with a copolyester structure, a controllable molecular weight, and a biodegradable macromolecular photoinitiator is a very potential solution.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a biodegradable macromolecular photoinitiator and its preparation and application, which overcome the problems of uncontrollable chemical structure, uncontrollable molecular weight, and content of initiating groups in the existing macromolecular initiators in the prior art. A low or large proportion of photolytic residues will volatilize and migrate, and the technical problem of low thermal stability of small-molecule photoinitiators and macromolecular photoinitiators is common.

The present invention provides a polyester shown in the following structure,

其中n、m为大于或等于2的整数；R₁为C2～C20的亚烃基；R₂为C1～C18的亚烃基。

wherein n and m are integers greater than or equal to 2; R ₁ is a C2-C20 hydrocarbylene group; R ₂ is a C1-C18 hydrocarbylene group.

The hydrocarbylene group is an alkylene group or an arylene group.

Preferably, the R ₁ is a C2-C10 hydrocarbylene group, and R2 is a C2-C4 hydrocarbylene group.

Preferably, the polyester has a number average molecular weight _Mn of 1.2k-100k, and a molecular weight distribution of 1.3-3.

Further preferably, the polyester has a number-average molecular weight of 1.2k-50k, more preferably, the number-average molecular weight is 1.2k-20k.

If the molecular weight is too low, it is no different from the small molecular photoinitiator, and cannot solve the problems of the prior art; if the molecular weight is too high, on the one hand, it will affect the dispersion of the polymer initiator in the matrix resin; There are adverse effects, and there is also the issue of aggregation costs. The reason for determining the range of the molecular weight distribution is that the molecular weight distribution is too high, which will affect the initiation efficiency, affect the dispersion, and affect the fluidity and processability of the matrix resin; if it is too low, low migration and sufficient heat resistance cannot be ensured.

The thermal decomposition temperature of the polyester can all reach ≥250°C.

The above-mentioned polyester (polymer photoinitiator), the thermal decomposition temperature is more than or equal to 250°C. In the present invention, the thermal decomposition temperature is the temperature at which the polymer photoinitiator loses weight by 5 wt% under nitrogen. Since the melt processing temperature of plastics, especially engineering plastics, is usually higher than 250°C, when a polymer photoinitiator is used for their modification, the thermal decomposition temperature of the polymer photoinitiator is preferably higher than 250°C. On the other hand, the present invention can significantly improve thermal stability by molecularizing the benzophenone fragments into a high molecular weight. Through the molecular design and polymerization process of the present invention, the thermal decomposition of the polyester (polymer photoinitiator) obtained in the present invention can be achieved. The temperature can reach ≥250℃.

The invention provides a preparation method of polyester, comprising:

(1) Esterification: mix benzophenone-4,4-dicarboxylic acid, aliphatic dibasic acid, aliphatic dihydric alcohol and catalyst (esterification catalyst) to carry out esterification reaction;

(2) Polycondensation: the product of step (1) is added with a catalyst (polymerization catalyst) and reacted to obtain a polyester (polymer copolyester photoinitiator).

The preferred mode of above-mentioned preparation method is as follows:

In the step (1), the aliphatic dibasic acid is one or more of C3-C20 dibasic acids; the aliphatic dibasic alcohol is one or more of C2-C20 dibasic alcohols.

In the step (1), the molar ratio of benzophenone-4,4-dicarboxylic acid, aliphatic dibasic acid and aliphatic dibasic alcohol is 0.1-0.9:0.1-0.9:1.0-4.0, and the esterification catalyst accounts for 0.02% to 2% of the total mass of the dibasic acid.

In the step (1), the reaction temperature is 150-200° C. and the reaction time is 2-12 h under the condition of protective gas.

The protective gas is nitrogen.

In the steps (1) and (2), the catalysts are all one or more of organic tin compounds, titanium compounds and antimony oxides.

Further, the catalyst is one or more of stannous octoate, stannous chloride, stannous acetate, tetrabutyl titanate, and antimony oxide.

In the step (2), the mass ratio of the polymerization catalyst to the esterification product is 0.02% to 2%.

In the step (2), the reaction temperature is 220-250° C., the pressure is lower than 200 Pa, and the time is 0.5-8 h.

The present invention provides a photoinitiator containing the structural polyester.

The invention provides an application of the photoinitiator in the field of photocurable coatings, inks, adhesives or photocrosslinking.

The present invention adopts esterification reaction, takes a certain proportion of benzophenone-4,4-dicarboxylic acid, aliphatic dibasic acid and aliphatic dihydric alcohol as raw materials, carries out esterification and polycondensation reaction, and obtains diphenylbenzene with composition Ketone functional copolyester photoinitiator.

The polymer initiator in the present invention is obtained by quantifying the high molecular weight of the benzophenone photoinitiator, and the obtained photoinitiator has a high molecular weight and is a polymer, so that when the modified resin is processed and molded at a high temperature, it will not generate The problem of failure due to the volatilization and thermal decomposition of benzophenone is good thermal stability; and the high molecular weight also eliminates the problem of affecting the surface properties of the product due to the migration of the photoinitiator in the resin product.

The polymer photoinitiator of the present invention is prepared by a polycondensation reaction. Polycondensation is a step-by-step polymerization, which is different from other chain polymerizations in that the polymerization speed is relatively slow, the molecular weight is easy to control, and the molecular weight distribution is narrower; Linear structure of polymeric photoinitiators. In addition, the polymer photoinitiator provided by the present invention is a copolymer in molecular structure, and the photoinitiating group benzophenone fragments are evenly distributed on the polymer chain, and the content is controllable, which can ensure high initiation efficiency, And endow the structure with degradability.

beneficial effect

(1) The preparation method of a polymer photoinitiator of the present invention has the advantages of easily available raw materials, low price, simple preparation process, and broad application prospect in the field of engineering plastics processing.

(2) A polymer photoinitiator of the present invention contains an aliphatic polyester segment and an aromatic polyester segment in the structure. By controlling benzophenone-4,4'-dicarboxylic acid and aliphatic binary The acid charge ratio can achieve the ratio of aliphatic to aromatic components in the biodegradable copolyester photoinitiator.

(3) A kind of polymer photoinitiator of the present invention has narrow molecular weight distribution, excellent photoinitiating effect, and the initiating group is located in the main chain, which can fundamentally overcome the problems of volatilization and migration of photoinitiated residues during photolysis of existing photoinitiators .

(4) A polymer photoinitiator of the present invention has excellent thermal stability and is suitable for cross-linking modification processing of engineering plastics.

Description of drawings

Fig. 1 is the characterization of the hydrogen nuclear magnetic spectrum of the photoinitiator PDBA obtained in Example 1;

Fig. 2 is the photopolymerization kinetics characterization diagram of PDBA, wherein (A) is the real-time infrared spectrum of PDBA; (B) is the double bond conversion rate of polyethylene glycol diacrylate monomer;

FIG. 3 is a graph showing the characterization of the mobility of the photoinitiator, wherein (A) is the mobility result of the photoinitiator BP and PDBA; (B) is a partial enlarged view of the mobility of the photoinitiator PDBA.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Example 1

(1) Put benzophenone-4,4'-dicarboxylic acid, adipic acid, and decanediol into the reaction device, add an esterification catalyst (stannous octoate) to the reaction system, replace it with nitrogen two times, and put it in nitrogen The temperature was gradually raised to 180 °C within 1 h under the atmosphere, and then esterified under normal pressure for 8 h to obtain an esterified product; among them, the molar ratio of benzophenone-4,4'-dicarboxylic acid, adipic acid, and decanediol was is 0.5:0.5:1.3, and the proportion of the total mass of the esterification catalyst and the dibasic acid is 2wt%.

(2) put a catalyst (stannous octoate) into the esterification product obtained in step (1), heat the reaction system to 220° C., and polymerize under 100Pa for 8 hours to obtain a polymer product (PDBA); wherein, the catalyst and the esterification product The mass ratio is 2 wt%.

A kind of polymer photoinitiator prepared, its nuclear magnetic characterization result is shown in accompanying drawing 1, and structural formula is as follows:

Among them, R1 is a C10 linear alkylene group; R2 is a C4 linear alkylene group; the number average molecular weight of the polymer photoinitiator is 31k, the molecular weight distribution is 2.2, the proportion of functional monomers is 0.52, and the polymer photoinitiator has a number average molecular weight of 31k and a molecular weight distribution of 2.2. The thermal decomposition temperature is 330℃.

Example 2

(1) Put benzophenone-4,4'-dicarboxylic acid, adipic acid and hexanediol into the reaction device, add an esterification catalyst (tetrabutyl titanate) to the reaction system, replace it with nitrogen twice and Under a nitrogen atmosphere, the temperature was gradually raised to 165 °C within 1 h, and then the esterification reaction was carried out under normal pressure for 7 h to obtain an esterified product; among which, benzophenone-4,4'-dicarboxylic acid, adipic acid, and hexanediol were charged. The molar ratio is 0.2:0.8:1.2, and the proportion of the total mass of the esterification catalyst and the dibasic acid is 0.04wt%.

(2) put a catalyst (tetrabutyl titanate) into the esterification product obtained in step (1), raise the temperature of the reaction system to 230° C., and polymerize for 2.5 hours under the condition of 200Pa to obtain a polymer product; wherein, the catalyst and the esterification product The mass ratio is 0.04 wt%.

The prepared polymer photoinitiator has the structural formula:

Among them, R1 is a straight-chain alkylene group of C6; R2 is a straight-chain alkylene group of C4; the number average molecular weight of the polymer photoinitiator is 10k, the molecular weight distribution is 1.8, the proportion of functional monomers is 0.23, and the polymer photoinitiator has a number average molecular weight of 10k and a molecular weight distribution of 1.8. The thermal decomposition temperature is 280℃.

Example 3

(1) Put benzophenone-4,4'-dicarboxylic acid, succinic acid, and decanediol into the reaction device, and add an esterification catalyst (stannous octoate) to the reaction system, replace it with nitrogen twice, and put it in nitrogen The temperature was gradually raised to 175 °C within 1 h under the atmosphere, and then esterified under normal pressure for 6 h to obtain an esterified product; among them, the molar ratio of benzophenone-4,4'-dicarboxylic acid, succinic acid, and decanediol was is 0.4:0.6:1.3, and the proportion of the total mass of the esterification catalyst and the dibasic acid is 0.1wt%.

(2) put a catalyst (stannous octoate) into the esterification product obtained in step (1), the reaction system is heated to 220 ° C, and polymerized for 4 h under the condition of 150Pa to obtain a polymerized product; wherein, the mass ratio of the catalyst to the esterified product is: 0.02 wt%.

The prepared polymer photoinitiator has the structural formula:

Among them, R1 is a C10 linear alkylene group; R2 is an ethyl group; the number-average molecular weight of the polymer photoinitiator is 15k, the molecular weight distribution is 3.0, the proportion of functional monomers is 0.42, and the thermal decomposition temperature of the polymer photoinitiator is 0.42. is 321°C.

Example 4

(1) Put benzophenone-4,4'-dicarboxylic acid, succinic acid, and hexanediol into the reaction device, add an esterification catalyst (tetrabutyl titanate) to the reaction system, replace it with nitrogen twice, and The temperature was gradually raised to 160 °C within 1 h under nitrogen atmosphere, and then esterified under normal pressure for 4 h to obtain an esterified product; among which, benzophenone-4,4'-dicarboxylic acid, succinic acid, and hexanediol were charged. The molar ratio is 0.6:0.4:1.1, and the proportion of the total mass of the esterification catalyst and the dibasic acid is 0.5wt%.

(2) put a catalyst (tetrabutyl titanate) into the esterification product obtained in step (1), heat the reaction system to 230°C, and polymerize for 2 h under the condition of 200Pa to obtain a polymer product; wherein, the quality of the catalyst and the esterification product The ratio is 0.5 wt%.

The prepared polymer photoinitiator has the structural formula:

Among them, R1 is a C6 straight-chain alkylene group; R2 is an ethyl group; the number-average molecular weight of the polymer photoinitiator is 6k, the molecular weight distribution is 1.3, the proportion of functional monomers is 0.65, and the thermal decomposition temperature of the polymer photoinitiator is 0.65. is 325°C.

Example 5

(1) Put benzophenone-4,4'-dicarboxylic acid, adipic acid, and ethylene glycol into the reaction device, add an esterification catalyst (antimony oxide) to the reaction system, replace it twice with nitrogen, and put it in a nitrogen atmosphere The temperature was gradually raised to 175 °C within 1 h, and then esterified under normal pressure for 4 h to obtain an esterified product; wherein, the molar ratio of benzophenone-4,4'-dicarboxylic acid, adipic acid, and ethylene glycol was 0.2:0.8:1.2, the proportion of the total mass of the esterification catalyst and the dibasic acid is 0.2wt%.

(2) put a catalyst (antimony oxide) into the esterification product obtained in step (1), heat the reaction system to 250°C, and polymerize for 1 h under the condition of 300Pa to obtain a polymer product; wherein, the mass ratio of the catalyst to the esterification product is 0.2 wt%.

The prepared polymer photoinitiator has the structural formula:

Among them, R1 is an ethyl group; R2 is a C4 linear hydrocarbon group; the number-average molecular weight of the polymer photoinitiator is 15k, the molecular weight distribution is 2.2, the proportion of functional monomers is 0.18, and the thermal decomposition temperature of the polymer photoinitiator is 0.18. is 250°C.

Example 6

(1) Put benzophenone-4,4'-dicarboxylic acid, adipic acid, and butanediol into the reaction device, add an esterification catalyst (tetrabutyl titanate) to the reaction system, replace it with nitrogen two times, and The temperature was gradually raised to 170°C within 1 h under nitrogen atmosphere, and then esterified under normal pressure for 2 h to obtain an esterified product; among them, benzophenone-4,4'-dicarboxylic acid, adipic acid, and butanediol were charged. The molar ratio is 0.7:0.3:1.5, and the proportion of the total mass of the esterification catalyst and the dibasic acid is 0.05wt%.

(2) put a catalyst (tetrabutyl titanate) into the esterification product obtained in step (1), raise the temperature of the reaction system to 240° C., and polymerize for 3 h under the condition of 200 Pa to obtain a polymer product; wherein, the quality of the catalyst and the esterification product is The ratio is 0.05 wt%.

The prepared polymer photoinitiator has the structural formula:

Among them, R1 is a straight-chain alkylene group of C4; R2 is a straight-chain alkylene group of C4; the number-average molecular weight of the polymer photoinitiator is 11k, the molecular weight distribution is 2.8, and the proportion of functional monomers is 0.77. The thermal decomposition temperature is 340℃.

Example 7

(1) Put benzophenone-4,4'-dicarboxylic acid, succinic acid, and ethylene glycol into the reaction device, add an esterification catalyst (antimony oxide) to the reaction system, replace it with nitrogen twice, and put it in a nitrogen atmosphere The temperature was gradually raised to 155 °C within 1 h, and then esterified under normal pressure for 5 h to obtain an esterified product; wherein, the molar ratio of benzophenone-4,4'-dicarboxylic acid, succinic acid, and ethylene glycol was 0.3:0.7:1.5, the proportion of the total mass of the esterification catalyst and the dibasic acid is 1wt%.

(2) put a catalyst (antimony oxide) into the esterification product obtained in step (1), heat the reaction system to 235 ° C, and polymerize it for 0.5 h under the condition of 200 Pa to obtain a polymerized product; wherein, the mass ratio of the catalyst to the esterified product is: 1 wt%.

The prepared polymer photoinitiator has the structural formula:

Among them, R1 is ethyl; R2 is ethyl; the number average molecular weight of the polymer photoinitiator is 1.2k, the molecular weight distribution is 2.3, the proportion of functional monomers is 0.33, and the thermal decomposition temperature of the polymer photoinitiator is 263 ℃ .

Example 8

(1) Put benzophenone-4,4'-dicarboxylic acid, succinic acid, and butanediol into the reaction device, add an esterification catalyst (tetrabutyl titanate) to the reaction system, replace it with nitrogen two times, and Under a nitrogen atmosphere, the temperature was gradually raised to 160 °C within 1 h, and then the esterification reaction was carried out under normal pressure for 4 h to obtain an esterified product; among which, benzophenone-4,4'-dicarboxylic acid, succinic acid, and butanediol were charged. The molar ratio is 0.4:0.6:1.6, and the proportion of the total mass of the esterification catalyst and the dibasic acid is 0.06wt%.

(2) put a catalyst (tetrabutyl titanate) into the esterification product obtained in step (1), raise the temperature of the reaction system to 220° C., and polymerize for 2.5 h under the condition of 200Pa to obtain a polymer product; wherein, the catalyst and the esterification product are The mass ratio is 0.06 wt%.

The prepared polymer photoinitiator has the structural formula:

Among them, R1 is a C4 straight-chain alkylene group; R2 is an ethyl group; the number average molecular weight of the polymer photoinitiator is 20k, the molecular weight distribution is 2.1, the proportion of functional monomers is 0.45, and the thermal decomposition temperature of the polymer photoinitiator is 282°C.

Example 9

(1) The photoinitiator (PDBA) obtained in Example 1 was added to ultra-high molecular weight polyethylene in a proportion of 2wt%, mixed with chloroform solution, and the solvent was removed by rotary evaporation. Press and cut to obtain a polyethylene film with a size of 1 cm × 3 cm × 0.5 mm. The films were irradiated with UV light for 20s, 40s, 60s, 90s, 120s, and 150s respectively under the condition of LED@365nm and 980mW/ ^cm2 . The irradiated film was dissolved in the solvent decalin at 180 °C for 3 h, taken out and dried at 185 °C for 3 h. The irradiation time was 90 s when the gel content was the highest.

(2) The irradiation time is fixed at 90s, and the photoinitiator accounts for 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt% of the mass ratio of UHMWPE to carry out the crosslinking experiment, and the remaining methods are the same as the steps ( 1), the optimum addition content of photoinitiator PDBA is 1wt%, and the maximum gel content is 94.7%.

Example 10

The photoinitiator (PDBA) obtained in Example 1 was pressed into a film at 70° C. with a flat vulcanizer, and then cold-pressed to prepare a number of films with a size of 1cm×1cm×50μm. A 4-week hydrolysis experiment was carried out in an incubator at 37°C. The results showed that the final degradation rates were 11.6% and 10.4% at pH 7.4 and pH 2.4, respectively.

Example 11

The photoinitiator (PDBA) obtained in Example 1 was added to polyethylene glycol diacrylate (PEGDA400) with a number-average molecular weight of 400 at a ratio of 0.1% molar ratio, and the mixture was fully stirred and mixed at 50 degrees Celsius. LED@365nm was used. , 980mW/cm ² irradiated for 0～60s, respectively irradiated 0s, 0.5s, 1s, 5s, 10s, 30s, 60s to prepare the cured film products by infrared spectrum test, to study the photoinitiator's photoinitiated activity and double bond Conversion rate, the results show that the conversion rate of the double bond of the macromolecular photoinitiator PDBA to the PEGDA monomer is 52.6%, and the results can be seen in Figure 2.

Example 12

The photoinitiator (PDBA) and benzophenone (BP) obtained in Example 1 were respectively added to polyethylene glycol diacrylate with a number average molecular weight of 400 in a ratio of 0.1% molar ratio, and the mixture was fully stirred and mixed at 50 degrees Celsius. Evenly, the corresponding cured film was obtained after irradiating with LED@365nm and 980mW/ ^cm2 for 60s. After cleaning the surfaces of the two cured films, take 0.1 g of each and soak them in 20 mL of chloroform solution for 1 h, 2 h, 3 h, 4 h and 5 h, respectively. The solution after soaking for each time is tested by ultraviolet absorption spectrum, and calculated by the absorbance mobility and compare. The final result is that the mobility of the BP-PEGDA system in chloroform for 5 hours is 1.16%; while the mobility of the PDBA-PEGDA system in chloroform for 5 hours is 0.0046%, as shown in Figure 3.

Claims (10)

1. A polyester shown in the following structure,

wherein n and m are integers greater than or equal to 2; R ₁ is a C2-C20 hydrocarbylene group; R ₂ is a C1-C18 hydrocarbylene group. 2 . The polyester according to claim 1 , wherein the R ₁ is a C2-C10 hydrocarbylene group, and R2 is a C2-C4 hydrocarbylene group; the polyester has a number-average molecular weight _Mn of 1.2k～2. 3 . 100k. 3. a preparation method of polyester, comprising: (1) mixing benzophenone-4,4-dicarboxylic acid, aliphatic dibasic acid, aliphatic dihydric alcohol and catalyst to react; (2) The product of step (1) is added to the catalyst again, and the reaction is carried out to obtain a polyester. 4. The preparation method according to claim 3, wherein in the step (1), the aliphatic dibasic acid is one or more of the dibasic acids of C3～C20; the aliphatic dihydric alcohol is C2 One or more of ~C20 diols. 5. preparation method according to claim 3 is characterized in that, in described step (1), the mol ratio of benzophenone-4,4-dicarboxylic acid, aliphatic dibasic acid and aliphatic dibasic alcohol is 0.1 ~0.9:0.1~0.9:1.0~4.0. 6 . The preparation method according to claim 3 , wherein the reaction in the step (1) is under protective gas conditions, the reaction temperature is 150-200° C., and the time is 2-12 h. 7 . 7 . The preparation method according to claim 3 , wherein the catalysts in the steps (1) and (2) are one or more of organic tin compounds, titanium compounds and antimony oxides. 8 . 8 . The preparation method according to claim 3 , wherein the reaction temperature in the step (2) is 220-250° C., the pressure is lower than 200 Pa, and the time is 0.5-8 h. 9 . 9 . A photoinitiator, wherein the photoinitiator comprises the polyester of claim 1 . 10 . 10. An application of the photoinitiator of claim 9 in the field of photocurable coatings, inks, adhesives or photocrosslinking.

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