CN110606935A

CN110606935A - Chain extender and preparation method thereof

Info

Publication number: CN110606935A
Application number: CN201910931616.3A
Authority: CN
Inventors: 刘仁; 罗静; 张丽萍; 孙凯强; 戴豪杰
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2019-12-24
Anticipated expiration: 2039-09-29
Also published as: CN110606935B

Abstract

The invention provides a chain extender which has a structure represented by a general formula 1 and can carry out epoxy ring-opening reaction through two carboxyl groups on a chain extender molecule and an epoxy group on epoxy resin. Therefore, on the basis of not changing the advantages of the resin structure and performance, other performances of the resin are improved in a targeted manner by adjusting the structure of the chain extender, such as improving water resistance by grafting a long alkyl chain or a benzene ring, improving adhesion of a metal substrate by grafting a phosphate ester or isobornyl ester structure, improving hardness by grafting a benzene ring, and the like, and reducing the viscosity of the resin by grafting a vinyl ether or long alkyl chain structure.

Description

Chain extender and preparation method thereof

Technical Field

The invention relates to a chain extender and a preparation method thereof, belonging to the technical field of resin synthesis.

Background

Bisphenol A epoxy acrylate is widely used in photocureable coating due to the advantages of high curing rate, high hardness of a cured coating film and the like, but the curing shrinkage is large due to the high curing rate, the internal stress between the coating film and a substrate is large, so that the adhesion of the coating film is poor, and the cured coating film is hard and brittle and is not suitable for substrates such as metal and the like. Thereby limiting its range of application. At present, a plurality of methods are used for researching the modification of epoxy acrylate, particularly the chain extension of epoxy acrylate by diacid chain extension technology, but the methods do not have the general type of modification approaches, the performance of the whole coating film is adjusted by changing a specific structure, and most of the technical schemes do not have good flexibility and low resin viscosity.

As disclosed in patent publication No. CN 105218784B, epoxy chain extension using organic acid such as adipic acid, maleic anhydride or dodecanoic acid can only reduce the viscosity of the resin, but cannot significantly improve the water resistance and mechanical properties. The patent publication No. CN 103524712A uses ethylene glycol and 1, 4-butanediol to modify epoxy, the reaction condition is harsh, the catalyst requirement is high, and the modification cost is increased. The viscosity of the synthesized resin is not obviously reduced.

Disclosure of Invention

In view of the above problems, it is an object of the present invention to provide a chain extender having a structure represented by general formula 1:

wherein R is₁Including H or CH₃；

Wherein R2 includes an alkyl group, a carboxyl group, a hydroxyl group, a carbamate group, a carbonate group, an amide group, an ester group, an alkoxy group, or any group selected from:

is the radical junction.

In one embodiment, the alkyl group includes a straight chain alkyl group, a branched chain alkyl group, a cyclic alkyl group, and the number of carbon atoms in the alkyl group is 5 to 20.

In one embodiment, the alkyl group includes the following structure:

is the radical junction.

In one embodiment, the chain extender comprises

The invention also aims to provide a preparation method of the chain extender, which comprises the step of reacting mercaptosuccinic acid and a compound represented by a general formula 2 serving as raw materials under the conditions of a catalyst and an acid-binding agent

Wherein R is₁、R₂And R as described in claim 1₁、R₂The same is true.

In one embodiment, the mol ratio of mercaptosuccinic acid to the compound represented by the general formula 2 is 1:1, the catalyst comprises triethylamine, and the reaction time is 5-8 h.

It is another object of the present invention to provide a use of the above chain extender for reacting with a functional group on a resin to improve the structure and properties of the resin.

In one embodiment, the reaction is carried out by taking resin, a chain extender and acrylic acid as raw materials and under the conditions of a catalyst and a polymerization inhibitor, wherein the concentration of the resin is 40-50%, the concentration of the chain extender is 10-30%, the concentration of the acrylic acid is 20-40%, the concentration of the catalyst is 0.1-2% of the total mass, and the concentration of the polymerization inhibitor is 0.06-0.1% of the total mass.

In one embodiment, the catalyst comprises triphenylphosphine TPP or tin ethylhexanoate, and the polymerization inhibitor comprises p-methoxyphenol.

In one embodiment, the resin comprises bisphenol a epoxy resin, hydrogenated bisphenol a epoxy resin, alicyclic epoxy resin, novolac epoxy resin; preferably, the resin is a bisphenol a epoxy resin.

Has the advantages that:

the chain extender provided by the invention can carry out epoxy ring-opening reaction through two carboxyl groups on the chain extender molecule and an epoxy group on the epoxy resin. Therefore, other properties of the resin, such as water resistance, adhesive force, hardness and the like, are purposefully improved by adjusting the structure of the chain extender on the basis of not changing the advantages of the structure and the performance of the resin, and the chain extender has the characteristic of low viscosity.

The preparation method comprises the step of carrying out mercaptoalkene Michael addition reaction on mercaptosuccinic acid and a photocuring active diluent with an acryloyloxy group structure to prepare a chain extender. The reaction is a conjugate addition reaction carried out by utilizing an electrophilic electron acceptor and nucleophilic carbanions, and has the advantages of easily obtained raw materials and wide application range; the operation is simple and convenient, the reaction condition is mild, and the reaction is not sensitive to water and oxygen; high yield, simple post-treatment and the like.

Drawings

FIG. 1 is a nuclear magnetic resonance spectrum of chain extender A1;

FIG. 2 is a nuclear magnetic resonance spectrum of isobornyl acrylate and chain extender A2.

Detailed Description

Example 1 preparation of chain extender a1

Weighing 0.1mol of mercaptosuccinic acid, putting the mercaptosuccinic acid into a 250ML single-neck flask, dissolving mercaptosuccinic acid by using 60g of acetone, ultrasonically stirring until the mercaptosuccinic acid is completely dissolved, then adding 0.1mol of dodecyl acrylate (LA), and adding 0.2mol of triethylamine as a catalyst and an acid-binding agent after the mercaptosuccinic acid is completely dissolved. Stirring and reacting for 6h at normal temperature. The acetone solvent was rotary evaporated. Dissolving the reacted substance in sufficient deionized water, adding sufficient hydrochloric acid to adjust the pH to be less than 1, extracting the chain extender with sufficient ethyl acetate, and dissolving other impurities in the deionized water. Extracting the chain extender dissolved in the ethyl acetate, putting the chain extender into a 250ml single-neck flask, and then carrying out rotary evaporation at the temperature of 80 ℃ to remove the ethyl acetate to obtain the chain extender A1 (LA-MSA). Nuclear magnetism as in fig. 1, the successful synthesis of chain extender a1 was demonstrated.

The reaction formula is as follows:

example 2 Synthesis of epoxy acrylate B1

The raw materials were added to a 100ml three-necked flask according to the ratio in Table 1, and the flask was put in an oil bath for heating reaction, and a thermometer, a stirring paddle and a dropping funnel were inserted into the three-necked flask, respectively. The reaction temperature is 100-120 ℃, the acid value of the system is measured after the system is heated and stirred for four hours, and the reaction is finished when the acid value is reduced to be less than 1mg KOH/g. The synthesized product is epoxy acrylate B1.

The structural formula of the epoxy acrylate B1 is as follows:

the viscosity and molecular weight of the modified epoxy acrylate B1 were measured, and the results are shown in Table 2, which shows that the synthesized resin has low molecular weight and low viscosity.

TABLE 1

Substance(s)	Quality of
		Chain extender A1	7.65g
Acrylic acid	2.86g
		Bisphenol A epoxy resin	13g
Catalyst TPP	0.12g
		P-methoxyphenol	0.014g

TABLE 2

GPC conditions:

a pump: l-6200 type (trade name, manufactured by Hitachi, Ltd.)

A chromatographic column: TSKgel-G5000HXL and TSKgel-G2000HXL (trade name, manufactured by Tosoh Corp.)

A detector: l-3300RI type (product name, manufactured by Hitachi, K.K.)

Eluent: tetrahydrofuran (THF)

Measuring temperature: 30 deg.C

Flow rate: 1.0 ml/min

Example 3 use of epoxy acrylate B1

Epoxy acrylate B1 was formulated into a coating formulation with acrylate reactive diluents HDDA (1, 6-hexanediol diacrylate), TPDGA (tripropylene glycol diacrylate) or DPGDA (dipropylene glycol diacrylate), 1173 photoinitiator according to the following proportions in Table 3. Coating the mixture into a film by using a film scraping instrument, and then irradiating and curing the film under a 365nm ultraviolet lamp.

TABLE 3

Substance(s)	Mass percent
		Modified epoxy acrylate	78％
Active diluent HDDA	20％
		1173 photoinitiator (2-hydroxy-methyl phenyl propane-1-ketone)	2％

The pencil hardness, the hundred lattice test, the impact test and the bending test were respectively carried out using GB T6739-. Thus, the modified epoxy acrylate synthesized according to the patent technology has the advantages of high hardness, excellent adhesion, good impact resistance and flexibility.

TABLE 4

Test items	Test results	Test standards or instruments
			Hardness of pencil	3H	GB T 6739-1996
Baige test	Level 0	GB9286
			Impact test	80kg.cm	GB/T 1732-93
Bending test	0.5T	ISO 1519

Example 4 preparation of chain extender a2

Weighing 0.1mol of mercaptosuccinic acid, putting the mercaptosuccinic acid into a 250ML single-neck flask, dissolving mercaptosuccinic acid by using 60g of acetone, ultrasonically stirring until the mercaptosuccinic acid is completely dissolved, then adding 0.1mol of isobornyl acrylate (IBOA), and adding 0.2mol of triethylamine as a catalyst and an acid-binding agent after the mercaptosuccinic acid is completely dissolved. Stirring and reacting for 6h at normal temperature. After the acetone solvent is removed by rotary evaporation, water is added for dilution, hydrochloric acid HCl is added for acidification, the product is added into a separating funnel, sufficient ethyl acetate is added for extraction, the water layer is on the lower layer, and triethylamine hydrochloride, unreacted reactant and other impurities are dissolved in water. After the ethyl acetate layer of the upper layer was evaporated to remove ethyl acetate, the reaction was continued until purified chain extender A2(IBOA-MSA) was obtained. The nuclear magnetic map of fig. 2 shows the successful synthesis of a 2.

The reaction formula is as follows:

example 5 Synthesis of epoxy acrylate B2

The mixture was placed in a three-necked flask equipped with a stirrer and a thermometer in the proportions shown in Table 5. Heating to 105 ℃, and when the acid value in the system is reduced to be less than 1mg KOH/g, finishing the reaction, wherein the synthesized product is the modified epoxy acrylate B2 (the structural formula is shown in the specification).

TABLE 5

Substance(s)	Quality of
		Chain extender A2	2.5g
Acrylic acid	8g
		Bisphenol A epoxy resin	14g
Catalyst TPP	0.15g
		Polymerization inhibitor MEHQ	0.012g

Example 6 use of epoxy acrylate B2

Epoxy acrylate B2 was formulated into a coating formulation with acrylate reactive diluents HDDA (1, 6-hexanediol diacrylate), TPDGA (tripropylene glycol diacrylate) or DPGDA (dipropylene glycol diacrylate), 1173 photoinitiator according to the following ratio in Table 6. Coating the mixture into a film by using a film scraping instrument, and then irradiating and curing the film under a 365nm ultraviolet lamp.

TABLE 6

Substance(s)	Mass percent
		Modified epoxy acrylate B2	78％
Active diluent HDDA	20％
		1173 photoinitiator (2-hydroxy-methyl phenyl propane-1-ketone)	2％

The results of the pencil hardness, the hundred lattice test, the impact test, and the bending test were carried out using GB T6739-. The modified epoxy acrylate synthesized by the chain extender provided by the invention has high pencil hardness and good flexibility. The adhesive force is excellent. Can be applied to ultraviolet curing coatings or electron beam curing coatings of paper, plastics and metal substrates.

TABLE 7

Test items	Test results	Test standards or instruments
			Hardness of pencil	3H	GB T 6739-1996
Baige test	Level 0	GB9286
			Impact test	100kg.cm	GB/T 1732-93
Bending test	1T	ISO 1519

Example 7 preparation of chain extender A3

Weighing 0.1mol of mercaptosuccinic acid, putting the mercaptosuccinic acid into a 250ML single-neck flask, dissolving mercaptosuccinic acid by using 60g of acetone, ultrasonically stirring until the mercaptosuccinic acid is completely dissolved, then adding 0.1mol of ethoxy ethyl acrylate (EOEOEA), and adding 0.2mol of triethylamine as a catalyst and an acid-binding agent after the mercaptosuccinic acid is completely dissolved. Stirring and reacting for 6h at normal temperature. And (3) evaporating the acetone solvent, adding water for dilution, adding hydrochloric acid (HCl) for acidification, adding the product into a separating funnel, adding sufficient ethyl acetate for extraction, wherein the water layer is at the lower layer, and dissolving triethylamine hydrochloride, unreacted reactant and other impurities in water. The ethyl acetate layer as the upper layer was subjected to rotary evaporation to remove ethyl acetate, to obtain a purified chain extender a 3.

The reaction formula is as follows:

example 8 Synthesis of epoxy acrylate B3

The mixture was charged into a three-necked flask equipped with a stirrer and a thermometer in the proportions shown in Table 8. Heating to 105 ℃, and when the acid value in the system is reduced to be less than 1mg KOH/g, finishing the reaction, wherein the synthesized product is the modified epoxy acrylate B3 (the structural formula is shown in the specification).

TABLE 8

Substance(s)	Quality of
		Chain extender A3	2.5g
Acrylic acid	8g
		Bisphenol A epoxy resin	14g
Catalyst TPP	0.15g
		Polymerization inhibitor MEHQ	0.012g

B3 synthetic structure is as follows

Example 9 use of epoxy acrylate B3

Epoxy acrylate B3 was formulated into a coating formulation with acrylate reactive diluents HDDA (1, 6-hexanediol diacrylate), TPDGA (tripropylene glycol diacrylate) or DPGDA (dipropylene glycol diacrylate), 1173 photoinitiator according to the following ratio in Table 9. Coating the mixture into a film by using a film scraping instrument, and then irradiating and curing the film under a 365nm ultraviolet lamp.

TABLE 9

Substance(s)	Mass percent
		Modified epoxy acrylate B2	50-80％
Active diluent HDDA	15-25％
		1173 photoinitiator (2-hydroxy-methyl phenyl propane-1-ketone)	2-3％

The properties of the modified epoxy acrylate resins and coatings synthesized using ethoxyethoxyethyl acrylate (EOEOEA) are shown in table 10 below:

watch 10

Test items	Test results	Test standards or instruments
			Hardness of pencil	2H	GB T 6739-1996
Baige test	Level 1	GB9286
			Impact test	70kg.cm	GB/T 1732-93
Bending test	1T	ISO 1519

The synthesized modified epoxy acrylate pencil has high hardness and good flexibility. The adhesive force is excellent. Can be applied to ultraviolet curing coatings of paper, plastics and metal substrates.

Claims

1. A chain extender, characterized in that the chain extender has a structure represented by general formula 1:

wherein R is₁Including H or CH₃；

is the radical junction.

2. The chain extender of claim 1, wherein the alkyl group comprises a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, and the number of carbon atoms in the alkyl group is 5 to 20.

3. A chain extender in accordance with claim 1 or 2, wherein said alkyl group comprises the structure:

is the radical junction.

4. A chain extender in accordance with claim 1, wherein said chain extender comprises

5. The preparation method of the chain extender as claimed in claim 1, wherein the method comprises the step of reacting mercaptosuccinic acid and a compound represented by a general formula 2 as raw materials under the conditions of a catalyst and an acid-binding agent

Wherein R is₁、R₂And R as described in claim 1₁、R₂The same is true.

6. The preparation method of the chain extender according to claim 5, wherein the mol ratio of mercaptosuccinic acid to the compound represented by the general formula 2 is 1:1, the catalyst comprises triethylamine, and the reaction time is 5-8 h.

7. Use of a chain extender in accordance with claim 1 or 2 to react with functional groups on the resin to improve the structure and properties of the resin.

8. The use of the chain extender according to claim 7, wherein the reaction is carried out by taking resin, a chain extender and acrylic acid as raw materials under the conditions of a catalyst and a polymerization inhibitor, wherein the concentration of the resin is 40-50%, the concentration of the chain extender is 10-30%, the concentration of the acrylic acid is 20-40%, the catalyst is 0.1-2% of the total mass, and the polymerization inhibitor is 0.06-0.1% of the total mass.

9. The use of a chain extender in accordance with claim 8 wherein the catalyst comprises triphenylphosphine TPP or tin ethylhexanoate and the polymerization inhibitor comprises p-methoxyphenol.

10. Use of a chain extender in accordance with claim 7 or 8 wherein said resin comprises bisphenol a epoxy resin, hydrogenated bisphenol a epoxy resin, alicyclic epoxy resin, novolac epoxy resin; preferably, the resin is a bisphenol a epoxy resin.