阅读说明：本技术 一种液晶环氧光敏树脂及其制备方法 (Liquid crystal epoxy photosensitive resin and preparation method thereof ) 是由 卓东贤 陈少云 华文强 李文颖 孙晓露 瞿波 王睿 郑燕玉 刘小英 李文杰 于 2021-09-28 设计创作，主要内容包括：本发明公开了一种液晶环氧光敏树脂及其制备方法。将含介晶基元且端部带有-OH的化合物、环氧氯丙烷和催化剂混合,通入N-(2)保护,在40～100℃下反应得到溶液A；滴加NaOH到溶液A中,去除反应生成的水,继续反应0.1～4小时后将产物过滤除去NaCl,将所得滤液除去多余的EHC,得到溶液B；溶液B与甲醇/丙酮溶液混合,降温结晶,得到的结晶物用甲醇洗涤并抽滤、烘干,得到液晶环氧光敏树脂。本发明提供的液晶环氧光敏树脂具有液晶有序和网络交联两者的优势,从而使液晶环氧树脂具有优良的光、电性能和较好的热机械性能,又可以通过紫外光照射来实现其固化,尺寸收缩率低,有效解决了其成型性差的缺点,而且具有固化速度快、生产效率高、污染小、节省能源等优点。(The invention discloses a liquid crystal epoxy photosensitive resin and a preparation method thereof. Mixing a compound containing mesomorphic elements and having-OH at the end, epichlorohydrin and a catalyst, and introducing N 2 Protecting, and reacting at 40-100 ℃ to obtain a solution A; dropwise adding NaOH into the solution A, removing water generated in the reaction, continuously reacting for 0.1-4 hours, filtering the product to remove NaCl, and removing redundant EHC from the obtained filtrate to obtain a solution B; and mixing the solution B with a methanol/acetone solution, cooling and crystallizing, washing the obtained crystal with methanol, filtering, and drying to obtain the liquid crystal epoxy photosensitive resin. The liquid crystal epoxy photosensitive resin provided by the invention has the advantages of liquid crystal order and network crosslinking, so that the liquid crystal epoxy resin has excellent optical and electrical properties and better thermal mechanical properties, and can be cured by ultraviolet irradiation, and the size of the liquid crystal epoxy photosensitive resin is largerThe shrinkage rate is low, the defect of poor formability is effectively overcome, and the curing agent has the advantages of high curing speed, high production efficiency, low pollution, energy conservation and the like.)

1. A preparation method of liquid crystal epoxy photosensitive resin is characterized by comprising the following steps: the method comprises the following steps:

(1) mixing a compound containing mesomorphic elements and having-OH at the end, epichlorohydrin and a catalyst, and introducing N₂Protecting, and then reacting for 5-24 hours at 40-100 ℃ to obtain a solution A;

(2) slowly dropwise adding a NaOH solution into the solution A, removing water generated in the reaction by using a vacuum pump under reduced pressure, continuously reacting for 0.1-4 hours, pouring the product into a separating funnel, filtering to remove NaCl, and removing redundant epoxy chloropropane from the obtained filtrate by using a rotary evaporator to obtain a solution B;

(3) and mixing the solution B with a methanol/acetone solution, cooling and crystallizing, washing and filtering the obtained crystal with methanol, and drying the product in an oven to obtain the liquid crystal epoxy photosensitive resin.

2. The method for preparing a liquid crystal epoxy photosensitive resin according to claim 1, wherein: the mesogen-containing compound with-OH at the end is one or a combination of 4-hydroxyphenyl 4-hydroxybenzoate, 4 '-biphenol, 3',5,5 '-tetramethylbiphenol, 4- ((4-hydroxyphenoxy) carbonyl) phenyl 4-hydroxybenzoate, 2, 3-bis (4-hydroxyphenyl) acrylonitrile and 4,4' -propylidenebisphenol in step (1).

3. The preparation method of the liquid crystal epoxy photosensitive resin according to claim 1, characterized in that: the catalyst in the step (1) is one or a combination of tetramethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetraethylammonium bromide, tetrabutylammonium hydrogen sulfate, benzyltriethylammonium chloride, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride or tetradecyltrimethylammonium chloride.

4. The method for preparing a liquid crystal epoxy photosensitive resin according to claim 1, wherein: the concentration of the NaOH solution in the step (2) is 30-60%.

5. The method for preparing a liquid crystal epoxy photosensitive resin according to claim 1, wherein: the ratio of the solution B to the methanol/acetone solution in the step (3) is 1.0: 0.1-1.0: 10.

6. The method for preparing a liquid crystal epoxy photosensitive resin according to claim 1, wherein: and (4) drying the product in the step (3) at the temperature of 60-100 ℃.

7. A liquid crystal epoxy photosensitive resin is characterized in that: which is obtained by the production method according to any one of claims 1 to 6.

Technical Field

The invention relates to the technical field of ultraviolet curing materials, in particular to a liquid crystal epoxy photosensitive resin and a preparation method thereof.

Background

Ultraviolet (UV) curing is a type of radiation curing, which is a process that uses ultraviolet light to initiate the rapid conversion of a chemically reactive liquid material into a solid material. The ultraviolet curing technology is considered as an environment-friendly green technology, also called as 3E technology, namely energy-saving, environment-friendly and economical. The ultraviolet light curing resin is a photosensitive resin with relatively low molecular weight, and has groups capable of performing light curing reaction, such as various unsaturated double bonds or epoxy groups. At present, ultraviolet curing resin mainly comprises epoxy acrylate, polyurethane acrylic resin and polyester acrylic resin. Although these resins can be used in many fields at present, they generally have poor water resistance and high temperature resistance and large curing shrinkage. Therefore, the development of a novel high-performance ultraviolet curing resin is of great practical significance.

Liquid Crystal Epoxy (LCER) is an important thermosetting liquid crystal polymer material. The molecular structure of the thermosetting liquid crystal polymer contains easy-oriented mesomorphic elements and reactive epoxy groups, and the thermosetting liquid crystal polymer is a thermosetting liquid crystal polymer which is cured to form a network structure with molecular crosslinking and high order after reaction under specific conditions. Under the participation of a curing agent, special groups in LCER molecules can perform curing reaction with the curing agent, the structures of the epoxy compound and the curing agent can be changed in the reaction process, and then polymer networks with the same type and different structures can be quickly and easily synthesized, and the liquid crystal epoxy resin has the advantages of liquid crystal order and network crosslinking. The advantage enables the liquid crystal epoxy resin to have excellent optical and electrical properties and better thermo-mechanical properties, and also has the advantages of good water resistance, heat resistance and the like.

Many researchers at home and abroad are interested in the synthesis research of liquid crystal epoxy resins with various structures. In addition, because epoxy resins have good mechanical properties and mechanical properties, etc., and are widely and commonly used, researchers have conducted extensive research on capping mesogenic units with epoxy functional groups. The LCER produced by the method has more outstanding comprehensive performance, greatly improves the toughness of a cured product, brings some new physical and mechanical properties which are not possessed by the original material, can be applied to the fields of special coatings, nonlinear optical materials and the like, and has wide development potential. Therefore, an effective way for reducing the processing cost is sought, and the synthesis and manufacture of liquid crystal epoxy compounds with good comprehensive performance are certainly to become the development trend of LCER.

At present, most of liquid crystal epoxy resins are cured by heat, most of curing agents are amines, and due to the fact that a limited bond angle is formed between the amines and epoxy groups, linear arrangement of LCER is difficult to form in the curing process, so that the obtained cured product is few in ordered structure area or large in dispersity, and a multi-domain liquid crystal cross-linked network is formed. Conventional curing means cannot obtain a highly oriented crosslinked network of liquid crystals unless external force factors such as electric fields, magnetic fields, etc. are used. Obviously, curing under electromagnetic field conditions greatly increases the process difficulty. Therefore, there is a need for a simple, cost-effective method for maintaining a highly aligned arrangement of mesogen molecules even after curing, which has the advantages of fast curing speed, high production efficiency, less pollution, energy saving, cost reduction, etc., compared to other curing methods.

Therefore, the research on the ultraviolet-curable high-performance liquid crystal epoxy photosensitive resin has important theoretical significance and application value.

Disclosure of Invention

Aiming at the conditions and defects of the prior art, the invention aims to provide a liquid crystal epoxy photosensitive resin with excellent performance and simple synthesis process and a preparation method thereof. The liquid crystal epoxy photosensitive resin provided by the invention has excellent mechanical properties.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of liquid crystal epoxy photosensitive resin comprises the following steps:

(1) according to the mol, 10 parts of mesomorphic-containing compound with-OH at the end, 50-500 parts of epoxy chloropropane (EHC) and 0.1-1.0 part of catalyst are mixed as raw materials, and N is introduced₂Protecting, and then reacting for 5-24 hours at 40-100 ℃ to obtain a solution A;

(2) according to the molar ratio, slowly dripping 20-50 parts of NaOH solution (with the concentration of 30% -60%) into the solution A, and removing water generated by the reaction by using a vacuum pump under reduced pressure; after continuously reacting for 0.1-4 hours, pouring the product into a separating funnel, filtering to remove NaCl, and removing redundant EHC from the obtained filtrate by using a rotary evaporator to obtain a solution B;

(3) and mixing the solution B with a methanol/acetone solution (the ratio is 1.0: 0.1-1.0: 10), putting the mixture into a refrigerator for cooling and crystallizing, washing an obtained crystal with methanol, carrying out suction filtration, and drying a product in an oven at the temperature of 60-100 ℃ to obtain a milky white solid, namely the liquid crystal epoxy photosensitive resin.

Preferably, the mesogen-containing compound having-OH at the end is one or a combination of 4-hydroxyphenyl 4-hydroxybenzoate, 4 '-biphenyldiol, 3',5,5 '-tetramethylbiphenyldiol, 4- ((4-hydroxyphenoxy) carbonyl) phenyl 4-hydroxybenzoate, 2, 3-bis (4-hydroxyphenyl) acrylonitrile, and 4,4' -propylidenebisphenol.

Preferably, the catalyst in step (1) is one or a combination of tetramethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetraethylammonium bromide, tetrabutylammonium hydrogen sulfate, benzyltriethylammonium chloride, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride or tetradecyltrimethylammonium chloride, etc.

The preparation process of the liquid crystal epoxy photosensitive resin provided by the invention involves the following reactions:

compared with the prior art, the invention has the beneficial effects that: the liquid crystal epoxy photosensitive resin provided by the invention has the advantages of wide raw material source and simple synthesis process, and is suitable for large-scale production and application. The liquid crystal epoxy photosensitive resin has a molecular structure with a large number of rigid mesogens, and can generate an anisotropic mesomorphic domain in situ in a forming process, so that the liquid crystal epoxy photosensitive resin has excellent performances of self-reinforcement, high strength, high modulus and the like. Meanwhile, the grafted epoxy group can be cured by irradiation of ultraviolet light, the size shrinkage rate is low, the defect of poor formability is effectively overcome, and the method has the advantages of high curing speed, high production efficiency, low pollution, energy conservation and the like, and can be widely applied to the fields of adhesives, special coatings, nonlinear optical materials and the like.

Drawings

FIG. 1 shows the reactions involved in the process for preparing a liquid crystal epoxy photosensitive resin of the present invention.

FIG. 2 shows nuclear magnetic hydrogen spectrum of liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention: (¹H-NMR)。

FIG. 3 is a thermogravimetric analysis (TGA) curve of a liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention under a nitrogen atmosphere at a temperature rising rate of 10 ℃/min.

FIG. 4 is a DSC curve of the liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention in a nitrogen atmosphere at a temperature increase rate of 10 deg.C/min.

FIG. 5 is an XRD curve of a liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention

Detailed Description

Example 1

(1) 23.0g of 4-hydroxyphenyl 4-hydroxybenzoate, 230ml of Epichlorohydrin (EHC) and 0.5g of tetramethylammonium chloride were addedMixing the raw materials, and introducing N₂Protecting, and then reacting for 12 hours at 60 ℃ to obtain a solution A;

(2) then slowly dropwise adding NaOH solution (0.25mol, concentration of 45%) into the solution A, removing water generated in the reaction by using a vacuum pump under reduced pressure, continuously reacting for 0.5 hour, pouring the product into a separating funnel, filtering to remove NaCl, and removing redundant EHC from the obtained filtrate by using a rotary evaporator to obtain solution B;

(3) and mixing the solution B with a methanol/acetone solution (the ratio is 1.0:1.0), placing the mixture into a refrigerator for cooling and crystallizing, washing an obtained crystal with methanol, performing suction filtration, and drying a product in an oven at 60 ℃ to obtain a milky white solid, namely the liquid crystal epoxy photosensitive resin.

Referring to FIG. 2, it shows nuclear magnetic hydrogen spectrum of liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention: (¹H-NMR). 4 hydrogen proton peaks of mesogen benzene ring correspond to 4 characteristic peaks on 8.3-6.7 ppm, which indicates that the structure of mesogen is not destroyed. The peak of hydrogen proton on the epoxy group corresponds to the characteristic peak on 4.6-2.5 ppm

Referring to FIG. 3, it is a thermogravimetric analysis (TGA) curve of the liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention under nitrogen atmosphere with a temperature rise rate of 10 ℃/min. The initial thermal decomposition temperature was 161 ℃ and the maximum decomposition temperature was 392 ℃ which indicates that the liquid crystal-containing epoxy photosensitive resin had good heat resistance.

Referring to FIG. 4, it is a DSC curve of the liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention in a nitrogen atmosphere at a temperature increase rate of 10 ℃/min. From the DSC graph, a wider and large absorption peak appears at 101 ℃, the enthalpy change is relatively obvious, and the absorption peak represents the temperature of the liquid crystal monomer for converting from a smectic mode with higher order to a nematic mode with lower order; 114 ℃ in the figure represents the clearing point (T) of the liquid crystal monomer_i) At the temperature, the liquid crystal monomer is gradually changed from anisotropic phase to isotropic phase, and the liquid crystal phase disappears; a wide and large strong endothermic peak appears in the range of 172 ℃ to 256 ℃. The analysis shows that the liquid crystal epoxy photosensitive resin contains liquid crystal phase.

Referring to FIG. 5, it is an XRD pattern of the liquid crystal epoxy photosensitive resin prepared in example 1 of the present invention. It can be seen that 2 θ has a sharp and high-intensity diffraction peak at about 21 degrees, which indicates that a nematic mesomorphic domain is formed in the liquid crystal epoxy photosensitive resin, and the lattice spacing of the liquid crystal epoxy photosensitive resin is 13.8nm, which is determined according to the bragg equation, which sufficiently proves that the liquid crystal epoxy photosensitive resin is a liquid crystal monomer having a nematic structure.

Uniformly coating the prepared liquid crystal epoxy photosensitive resin on a glass sheet, and then carrying out ultraviolet light (100 mW/cm) at 365nm²) And (5) irradiating in an ultraviolet curing box under irradiation. And pouring the prepared resin into a grinding tool, and after the resin is completely cured by ultraviolet light, the surface of the product is smooth, and the Shore hardness is 80 HD.

Example 2

(1) 0.1mol of 4,4' -biphenol, 360ml of epoxy chloropropane (EHC) and 0.003mol of tetrabutylammonium bromide are taken as raw materials to be mixed, and N is introduced₂Protecting, and then reacting for 18 hours at 50 ℃ to obtain a solution A;

(2) slowly dropwise adding NaOH solution (0.30mol, the concentration of 40%) into the solution A according to the molar ratio, removing water generated in the reaction by using a vacuum pump under reduced pressure, continuously reacting for 2.5 hours, pouring the product into a separating funnel, filtering to remove NaCl, and removing redundant EHC from the obtained filtrate by using a rotary evaporator to obtain solution B;

(3) mixing the solution B with a methanol/acetone solution (the ratio is 1.0:3.0), and placing the mixture into a refrigerator for cooling and crystallizing. The resulting crystals were washed with methanol and filtered with suction. And drying the product in an oven at 80 ℃ to obtain a milky white solid, namely the liquid crystal epoxy resin.

Uniformly coating the prepared liquid crystal epoxy photosensitive resin on a glass sheet, and then carrying out ultraviolet light (100 mW/cm) at 365nm²) And (5) irradiating in an ultraviolet curing box under irradiation. And pouring the prepared resin into a grinding tool, and after the ultraviolet curing is completed, the surface of the product is smooth, and the Shore hardness is 68 HD.

Example 3

(1) 0.1mol of 3,3',5,5' -tetramethyl diphenol, 120ml of Epichlorohydrin (EHC) and 0.006mol of tetrabutylammonium chloride are taken as raw materials to be mixed, and N is introduced₂The protection is carried out on the surface of the steel pipe,then reacting for 6 hours at 80 ℃ to obtain a solution A;

(2) then slowly dropwise adding NaOH solution (0.20mol, the concentration of 60%) into the solution A, removing water generated in the reaction by using a vacuum pump under reduced pressure, continuously reacting for 4.0 hours, pouring the product into a separating funnel, filtering to remove NaCl, and removing redundant EHC from the obtained filtrate by using a rotary evaporator to obtain solution B;

(3) mixing the solution B with a methanol/acetone solution (the ratio is 1.0:0.5), and placing the mixture into a refrigerator for cooling and crystallizing. The resulting crystals were washed with methanol and filtered with suction. And drying the product in an oven at 100 ℃ to obtain a milky white solid, namely the liquid crystal epoxy resin.

Uniformly coating the prepared liquid crystal epoxy photosensitive resin on a glass sheet, and then carrying out ultraviolet light (100 mW/cm) at 365nm²) And (5) irradiating in an ultraviolet curing box under irradiation. And pouring the prepared resin into a grinding tool, and after the resin is completely cured by ultraviolet light, the surface of the product is smooth, and the Shore hardness is 85 HD.

Example 4

(1) 0.1mol of 4- ((4-hydroxyphenoxy) carbonyl) phenyl 4-hydroxybenzoate, 1050ml of Epichlorohydrin (EHC) and 0.01mol of tetraethylammonium bromide are used as raw materials to be mixed, and N is introduced₂Then reacting for 24 hours at 100 ℃ to obtain a solution A;

(2) then, a NaOH solution (0.40mol, 50% concentration) was slowly added dropwise to the solution A on a molar basis, the water generated by the reaction was removed under reduced pressure by a vacuum pump, the reaction was continued for 0.5 hour, the product was poured into a separatory funnel, NaCl was removed by filtration, and the obtained filtrate was subjected to removal of excess EHC by a rotary evaporator to obtain a solution B.

(3) Mixing the solution B with a methanol/acetone solution (ratio of 1.0:5.0), and placing the mixture into a refrigerator for cooling and crystallizing. The resulting crystals were washed with methanol and filtered with suction. And drying the product in an oven at 80 ℃ to obtain a milky white solid, namely the liquid crystal epoxy resin.

Uniformly coating the prepared liquid crystal epoxy photosensitive resin on a glass sheet, and then carrying out ultraviolet light (100 mW/cm) at 365nm²) And (5) irradiating in an ultraviolet curing box under irradiation. Pouring the prepared resin into a grinding tool, and after the resin is completely cured by ultraviolet light, the surface of the product is smooth, and the Shore hardness is 78HD。

Example 5

(1) 0.1mol of 2, 3-bis (4-hydroxyphenyl) acrylonitrile, 950ml of Epichlorohydrin (EHC) and 0.001mol of tetrabutylammonium hydrogen sulfate are used as raw materials to be mixed, and N is introduced₂Protecting, and then reacting for 10 hours at 40 ℃ to obtain a solution A;

(2) then, a NaOH solution (0.30mol, concentration 60%) was slowly added dropwise to the solution A on a molar basis, water generated by the reaction was removed under reduced pressure by a vacuum pump, the reaction was continued for 3.0 hours, the product was poured into a separatory funnel, NaCl was removed by filtration, and the obtained filtrate was subjected to removal of excess EHC by a rotary evaporator to obtain a solution B.

(3) Mixing the solution B with a methanol/acetone solution (the ratio is 1.0:10), and placing the mixture into a refrigerator for cooling and crystallizing. The resulting crystals were washed with methanol and filtered with suction. And drying the product in an oven at 90 ℃ to obtain a milky white solid, namely the liquid crystal epoxy resin.

Uniformly coating the prepared liquid crystal epoxy photosensitive resin on a glass sheet, and then carrying out ultraviolet light (100 mW/cm) at 365nm²) And (5) irradiating in an ultraviolet curing box under irradiation. And pouring the prepared resin into a grinding tool, and after the ultraviolet curing is completed, the surface of the product is smooth, and the Shore hardness is 75 HD.

Example 6

(1) 0.1mol of 4,4' -propylene biphenol, 120ml of Epichlorohydrin (EHC) and 0.002mol of benzyltriethylammonium chloride are taken as raw materials to be mixed, and N is introduced₂Then reacting for 12 hours at 60 ℃ to obtain a solution A;

(2) slowly dropwise adding NaOH solution (0.20mol, concentration of 45%) to the solution A, removing water generated in the reaction by using a vacuum pump under reduced pressure, continuously reacting for 1.0 hour, pouring the product into a separating funnel, filtering to remove NaCl, and removing redundant EHC from the obtained filtrate by using a rotary evaporator to obtain solution B;

(3) mixing the solution B with a methanol/acetone solution (ratio of 1.0:3.5), and placing the mixture into a refrigerator for cooling and crystallizing. Washing the obtained crystal with methanol, filtering, and drying the product in an oven at 80 ℃ to obtain milky white solid, namely the liquid crystal epoxy resin.

The prepared liquid crystal epoxy photosensitive resinUniformly coated on a glass plate, and then irradiated with 365nm ultraviolet light (100 mW/cm)²) And (5) irradiating in an ultraviolet curing box under irradiation. And pouring the prepared resin into a grinding tool, and after the ultraviolet curing is completed, the surface of the product is smooth, and the Shore hardness is 65 HD.