阅读说明：本技术 一种交联剂及其制备方法 (Crosslinking agent and preparation method thereof ) 是由 张啟衍 于 2020-08-12 设计创作，主要内容包括：本发明提供了一种交联剂,包括分子结构式为<Image he="135" wi="200" file="DEST_PATH_IMAGE002.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>的环氧基硅烷偶联剂,R代表烷基。本发明的有益效果是：该交联剂首先与羧基反应,反应产物再进行水解及脱水缩合,整个反应过程没有气体产生,另外该反应的最终产物是极性的,与水相容性很好,因此施工过程粘度不会变化,加入交联剂后保存长达8小时以上,非常好操作；在潮湿天气或通风条件差的环境施工时,交联剂不会和水反应,尽管在这种条件下主反应开始时间会延后(表干慢)但不会被消耗,没有气体放出也就不会产生针孔。(The invention provides a cross-linking agent, which comprises a molecular structural formula R represents an alkyl group. The invention has the beneficial effects that: the cross-linking agent firstly reacts with carboxyl, and the reaction product is hydrolyzed and dehydrated and condensed, so that no gas is generated in the whole reaction process, and in addition, the final product of the reaction is polar and has good compatibility with water, so that the viscosity cannot be changed in the construction process, and the cross-linking agent is added and then stored for more than 8 hours, so that the operation is very good; in humid daysIn the case of the environmental construction under poor gas or aeration conditions, the crosslinking agent does not react with water, and although the main reaction initiation time is delayed (tack-free time is slow) under such conditions, it is not consumed, and no pinholes are produced without gas evolution.)

1. A crosslinking agent characterized by: comprises a molecular structural formula of

R represents an alkyl group.

2. The crosslinking agent according to claim 1, wherein: the alkyl group is methyl or ethyl.

3. A method of preparing the crosslinking agent of claim 1, wherein: and uniformly mixing the epoxy silane coupling agent containing methyl and the epoxy silane coupling agent containing ethyl to obtain the cross-linking agent.

4. The method for producing a crosslinking agent according to claim 3, wherein: the ratio of the epoxy silane coupling agent containing a methyl group to the epoxy silane coupling agent containing an ethyl group is 1:1.

Technical Field

The invention relates to a cross-linking agent, in particular to a cross-linking agent and a preparation method thereof.

Background

The paint industry is generally divided into a single-component system and a two-component system, the single-component system is low in crosslinking density, hardness and sealing property and low in physical and chemical properties, and the two-component system is characterized in that a certain gene (such as hydroxyl) in resin can perform crosslinking reaction with a crosslinking agent (such as isocyanate), so that the crosslinking density of a paint film is greatly improved, and the paint film has the properties of high hardness, good sealing property, water resistance, stain resistance, acid resistance, alkali resistance and the like.

In order to improve the performance of the one-component coating, azapyridine is used as a cross-linking agent in the coating industry, but the cross-linking agent is low in efficiency, high in toxicity and finally eliminated.

The cross-linking agent (curing agent) used in the widely used water-based two-component coating is isocyanate (containing NCO bond), the resin used is hydroxypropyl resin or polyurethane dispersoid, the hydroxypropyl resin or the polyurethane dispersoid contains hydroxyl (OH), and the reaction mechanism is shown in figure 1.

Because of the side reaction, two disadvantages can appear in the construction process:

(1) after the system is added with the cross-linking agent, the side reaction of water and the cross-linking agent begins to be carried out, carbon dioxide gas is slowly released, and the other final product of the side reaction is as follows:

it has low polarity and poor compatibility with water, and the amount of the product increases gradually as the reaction proceeds, and the viscosity rises gradually due to poor compatibility with water, and generally cannot be used after 1-2 hours.

(2) In an environment with high humidity or poor ventilation, water is difficult to volatilize after the coating is coated, the water continuously reacts with the cross-linking agent to continuously consume the cross-linking agent, the main reaction can be started after the water is volatilized, the main reaction can not be sufficient due to the consumption of the cross-linking agent, the hardness is poor, and a large number of pinholes can be formed on the surface of a paint film due to continuous emission of carbon dioxide gas, so that the quality of the paint film can not meet the requirement.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a cross-linking agent and a preparation method thereof.

The invention provides a cross-linking agent, which comprises a molecular structural formula

R represents an alkyl group.

As a further development of the invention, the alkyl group is methyl or ethyl.

The invention also provides a preparation method of the cross-linking agent, which is characterized in that the epoxy silane coupling agent containing methyl and the epoxy silane coupling agent containing ethyl are uniformly mixed to obtain the cross-linking agent.

As a further improvement of the present invention, the ratio of said epoxy silane coupling agent containing a methyl group to said epoxy silane coupling agent containing an ethyl group is 1:1.

the invention has the beneficial effects that: through the scheme, the cross-linking agent firstly reacts with carboxyl, and the reaction product is hydrolyzed and subjected to dehydration condensation, so that no gas is generated in the whole reaction process, and in addition, the final product of the reaction is polar and has good compatibility with water, so that the viscosity cannot be changed in the construction process, the cross-linking agent is added and then is stored for more than 8 hours, and the operation is very good; in the case of construction in humid weather or in environments with poor ventilation conditions, the crosslinking agent does not react with water, and although the main reaction start time is delayed (tack-free) under such conditions, it is not consumed, and no pinholes are produced without gas evolution.

Drawings

FIG. 1 is a reaction mechanism of a cross-linking agent used in a water-based two-component coating widely used in the prior art.

FIG. 2 shows the reaction mechanism of epoxy and carboxyl groups of a cross-linking agent of the present invention.

Detailed Description

The invention is further described with reference to the following description and embodiments in conjunction with the accompanying drawings.

A cross-linking agent has a molecular structure of

R represents an alkyl group and may be a methyl group (CH)₃) It has a high hydrolysis rate and can also be ethyl (C)₂H₅) It has a slow hydrolysis rate.

The preparation method of the cross-linking agent selects and uses the epoxy silane coupling agent containing methyl and ethyl to be uniformly mixed (1:1) as the cross-linking agent, and has good stability and long activation period.

The cross-linking agent provided by the invention is applied to a carboxyl-containing aqueous single-component coating system to convert the carboxyl-containing aqueous single-component coating system into an aqueous two-component coating system, and if the cross-linking agent is applied to a carboxyl-containing and hydroxyl-containing aqueous two-component coating system, a three-component (two-curing agent) coating system can be formed. This greatly improves various physical and chemical properties of the coating.

As can be seen from the reaction of fig. 2:

(1) the theoretical ratio of the carboxyl group to the epoxy group is 1:1, while the effective component of the common commercial epoxy silane coupling agent is about 98%, and the experimental result shows that the ratio of the carboxyl group to the epoxy silane coupling agent in the resin is 1:1.2, and the reaction is sufficient.

(2) The epoxy crosslinking agent firstly reacts with carboxyl, the reaction product is hydrolyzed and dehydrated and condensed, no gas is generated in the whole reaction process, in addition, the final product of the reaction is polar and has good compatibility with water, so the viscosity cannot be changed in the construction process, the epoxy crosslinking agent is added and then is stored for more than 8 hours, and the operation is very good.

(3) In the case of construction in humid weather or in environments with poor ventilation conditions, the crosslinking agent does not react with water, and although the main reaction start time is delayed (tack-free) under such conditions, it is not consumed, and no pinholes are produced without gas evolution.

The invention provides a cross-linking agent, which has the following applications:

1. the cross-linking agent has single reaction with carboxyl, long storage period after the cross-linking agent is added, good construction, and little influence on the performance of a paint film when the cross-linking agent is used in a humid environment.

2. The cross-linking agent has lower market price than isocyanate, the addition amount is less, generally 6-8% of the coating, and the actual dosage is determined by the carboxyl content of the resin in the formula. The hardness of the Mitsubishi pencil can be improved by 2H by changing a single-component system into a double-component system, and the Mitsubishi pencil is high in cost performance and easy to popularize and apply.

3. Most of waterborne acrylic Acid (AC), waterborne polyurethane modified acrylic acid (PUA) and waterborne Polyurethane (PUD) resins contain carboxyl functional groups, so the cross-linking agent has wide application range and comprises waterborne terrace paint, waterborne wood paint, waterborne wall paint, waterborne leather paint, waterborne metal paint and the like.

4. The organic catalyst can reduce the activation energy of the reaction and greatly improve the reaction speed, the conventional two-component system needs at least 3 days for completing the reaction and the delivery and use, the temperature needs 4 to 5 days when being lower, the reaction can be completed within 12 hours when the temperature is high and 24 hours when the temperature is lower after a small amount of catalyst is added into the system.

5. The resin containing carboxyl and hydroxyl can be added with an epoxy cross-linking agent and an isocyanate cross-linking agent simultaneously, and the hardness of the Mitsubishi pencil can be improved by 2H.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.