New thioxanthone carboxylic ester photoinitiator and preparation method thereof

Abstract

The invention discloses a new thioxanthone carboxylic ester photoinitiator and a preparation method thereof. The invention relates to a preparation method of thioxanthone carboxylic ester. The thioxanthone carboxylic ester is a compound with the structure of a formula (I) as shown in the specification, wherein the carboxylic ester substituent group of the thioxanthone is at position 2 and position 4; each R1 is independently selected from hydrogen, halogen, C1-C12 alkyl, C3-C6 naphthenic base and C1-C12 alkoxy; each of R2 and R3 is independently selected from hydrogen, halogen, C1-C18 alkyl, C3-C6 naphthenic base and C1-C18 alkoxy; X is independently selected from multi-hydroxyl micromolecular compound (wherein the hydroxyl number is 2-6) and C1-C18 alkoxy; and m is 1-6. The preparation method overcomes the defect that the generally used thioxanthone carboxylic ester has low ester exchange activity by introducing a methyl lactate group and improving the condition of ester exchange reaction; the reaction condition is mild and ester exchange can be finished in a short time; and the preparation method is suitable for industrialized production.

Description

technical field [0001] The invention relates to a novel thioxanthone carboxylate photoinitiator and a preparation method of the photoinitiator. Background technique [0002] UV light curing technology is an environmentally friendly technology in the fields of coatings, inks, adhesives, etc. The main body of the material is generally composed of acrylic resin, polyol acrylate and photoinitiator. Under the action of enough ultraviolet light, all of them are cured. Compared with the traditional solvent-containing system, it has outstanding characteristics such as no solvent emission, high efficiency, and energy saving, so it is used in many fields. With the application of UV light-curing materials more and more widely, some unexpected problems have appeared, such as the baby milk incident in 2005. When a batch of baby milk was sampled and inspected, it was found that the printing of this batch of milk packaging materials contained a A chemical called isopropylthioxanthone (IT...

AI Technical Summary

Problems solved by technology

Under the increasing sensitivity to the pollution of foreign compounds in food and pharmaceutical packaging and the increasingly stringent environmental protection pressure, it is difficult for the currently commercially available thioxanthone photoinitiators to meet the above requirements, which have high activity, good compatibility, Macromolecular thioxanthone photoinitiators with low extraction, low migration and low volatility will gradually be recognized by the market

[0006] Patent CN101230056 discloses a class of macromolecular thioxanthone initiators, but the disadvantage is that the synthetic pollution of phenolic hydroxythioxanthone is relatively large, the waste water is difficult to treat, and the cost is high, which restricts the application of this type of photoinitiator

WO2003033492 discloses that 2-hydroxythioxanthone and various polyethers are used as raw materials to prepare multifunctional thioxanthone photoinitiated derivatives, but there is also the problem of large pollution in the synthesis of 2-hydroxythioxanthone

US200400559133 has improved the raw material synthesis process in the above-mentioned patents, eliminating the pollution of phenol, but the post-treatment of a large amount of concentrated sulfuric acid is also very difficult

US6025408 and US4594400 disclose the polymerizable monomer derived from thioxanthone carboxylic acid, and copolymerize with other monomers to obtain a macromolecular photoinitiator connected with thioxanthone ester derivatives in the polymerization side chain, but in In practical application, because of its high viscosity, there are great problems in the application process

[0007] CN200410093977.9 discloses that a class of thioxanthone-2-carboxylic acid derivatives exhibits low volatility, low extraction, and low migration characteristics, but the cost of raw materials for preparing such compounds is high, and their photoinitiating activity is slightly lower than that of thioxanthone-2-carboxylic acid derivatives. 4-Carboxylic acid derivatives, the practical application is limited

CN201010218422.8 discloses thioxanthone-4-carboxylic acid polyethylene glycol-200-diester, thioxanthone-4-carboxylic acid polyethylene glycol-300-diester, thioxanthone-4-carboxylic acid poly Tetrahydrofuran-250-diester has the characteristics of high activity, low volatility, low extraction, and low migration, but the melting point of this type of compound is not high, it is not easy to store and transport, it is difficult to maintain the appearance at a slightly higher room temperature, and it cannot be continuously produced; the compatibility is not good. High, increasing the difficulty of purification, but also increasing the difficulty of industrial production

Simultaneously, the preparation method of these two types of thioxanthone derivatives cannot be carried out by the transesterification of general thioxanthone carboxylate (such as methyl ester or ethyl ester), resulting in severe transesterification reaction conditions and severe The reaction is not easy to complete, making it difficult to scale up production on a large scale