阅读说明：本技术 一种高凝胶型粘接氯丁胶乳的制备方法 (Preparation method of high-gel type bonding neoprene latex ) 是由 曾维亮 叶伟 戴祖宏 于凯华 于 2019-10-31 设计创作，主要内容包括：本发明属于橡胶生产领域,具体公开了一种高凝胶型粘接氯丁胶乳的制备方法,包括水相配制、油相配制、助剂配制以及聚合四个步骤,所述助剂配制包括引发剂配制、终止剂配制以及乳化剂配制,乳化剂配制使用原料为非离子乳化剂,水相配制时也加入该非离子乳化剂,油相配制时加入歧化松香乳化剂。采用本发明的工艺,制备出的高凝胶型粘接氯丁胶乳性能更加优良。(The invention belongs to the field of rubber production, and particularly discloses a preparation method of high-gel bonded neoprene latex. The high-gel adhesive neoprene latex prepared by the process has better performance.)

1. A preparation method of high gel type bonding neoprene latex comprises four steps of water phase preparation, oil phase preparation, auxiliary agent preparation and polymerization, wherein the auxiliary agent preparation comprises initiator preparation, terminator preparation and emulsifier preparation, and is characterized in that: adding non-ionic emulsifier when preparing water phase, and adding disproportionated rosin emulsifier when preparing oil phase.

2. The process for preparing a highly gel-forming adhesive polychloroprene latex according to claim 1, wherein: the nonionic emulsifier is polyoxyethylene ether emulsifier solution.

3. The process for preparing a highly gel-forming adhesive polychloroprene latex according to claim 2, wherein: the water phase preparation step is to add liquid caustic soda, sodium carbonate and polyoxyethylene ether emulsifier in turn during the stirring process until the liquid caustic soda, the sodium carbonate and the polyoxyethylene ether emulsifier are completely dissolved.

4. The process for preparing a highly gel-forming adhesive polychloroprene latex according to claim 3, wherein: the preparation of the terminator comprises the following steps:

s1, preparation of terminating agent liquid A

Stirring and heating the soft water, and adding liquid alkali into the soft water for dissolving;

s2, preparing terminator solution B

Sequentially adding benzene, a disproportionated rosin emulsifier and an anti-aging agent in the stirring process;

s3, mixing

Mixing the terminating agent A liquid and the terminating agent B liquid at 40-45 ℃ and stirring.

5. The process for preparing the highly gel-type adhesive polychloroprene latex according to claim 4, wherein: the polymerization comprises the following steps:

s1, adding the oil phase and the water phase in sequence, stirring, and adding the emulsifier;

s2, adding an initiator and ammonia water;

s3, when the specific gravity of the latex reaches more than 1.10, adding the latex into a termination kettle, deeply turning for 8-12 hours, and adding a termination agent;

and S4, adding an antifreezing agent.

6. The method for preparing the adhesive polychloroprene latex with high gel content according to claim 5, wherein the method comprises the following steps: the antifreezing agent is urea solution.

7. The method for preparing the adhesive polychloroprene latex with high gel content according to claim 6, wherein the method comprises the following steps: the initiator is added in multiple portions.

8. The method for preparing the adhesive polychloroprene latex with high gel content according to claim 7, wherein the method comprises the following steps: the oil phase preparation step comprises the steps of adding a regulator into chloroprene, and adding a disproportionated rosin emulsifier after the regulator is dissolved.

9. The method for preparing the adhesive polychloroprene latex with high gel content according to claim 8, wherein the method comprises the following steps: an activator is added into the initiator.

10. The process for preparing a highly gel-forming adhesive polychloroprene latex according to claim 9, wherein: the addition amount of the regulator is 0.3-0.6%.

Technical Field

The invention belongs to the field of rubber production, and particularly relates to a preparation method of high-gel bonding neoprene latex.

Background

The neoprene latex is a high molecular polymer, belonging to one of neoprene products. Neoprene latex has strong adhesive force, so that the neoprene latex is often used for manufacturing adhesives and can be used for bonding various materials such as rubber, leather, fabrics, leatherworking, plastics, wood, paper products, glass, ceramics, concrete, metal and the like, and therefore, the neoprene latex is also called as 'universal adhesive'.

According to the gel content, the neoprene latex can be divided into three types of medium gel, high gel and sol type, in the prior art, more low molecular emulsifying agent is generally added in the preparation of the high gel type latex, and when the neoprene latex is used as a bonding material, the bonding time is short due to the migration of low molecules, so that the neoprene latex does not meet the requirements of the bonding material.

Disclosure of Invention

The invention aims to provide a preparation method of high-gel adhesive neoprene latex.

In order to achieve the purpose, the basic scheme of the invention is as follows: a process for preparing the high-gel adhesive chloroprene latex includes such steps as preparing water phase, preparing oil phase, preparing assistant including trigger, preparing terminator and emulsifier, preparing water phase while adding non-ionic emulsifier, and preparing oil phase while adding disproportionated rosin emulsifier.

The theory of operation and the beneficial effect of this basic scheme lie in:

and a nonionic emulsifier is added during emulsification, participates in the formation of micelles, and provides surface properties such as the thickness, the charge strength and the like of a micelle hydration layer. While the prior art adds nonionic emulsifier during latex production, the addition of too much nonionic emulsifier to the latex can affect the latex film forming speed and wet glue strength. The process adopts a large-component disproportionated rosin and a small amount of non-ionic emulsifier, and has no other synthetic emulsifier, thereby effectively avoiding the defects.

Further, the nonionic emulsifier is polyoxyethylene ether emulsifier solution.

Has the advantages that: the polyoxyethylene ether has a proper HLB value and can be used as an emulsifier to form a stable emulsion with a small dosage.

Further, the water phase preparation step is to add liquid caustic soda, sodium carbonate and polyoxyethylene ether emulsifier in turn during the stirring process until the liquid caustic soda, the sodium carbonate and the polyoxyethylene ether emulsifier are completely dissolved.

Has the advantages that: sodium carbonate is added into the water phase, and during polymerization and storage, the sodium carbonate can neutralize hydrogen chloride generated during polymerization and removed from the neoprene latex during storage, and buffer the reduction of PH so as to maintain the stability of the neoprene latex during polymerization and storage.

Further, the preparation of the terminator comprises the following steps:

s1, preparation of terminating agent liquid A

Stirring and heating the soft water, and adding liquid alkali into the soft water for dissolving;

s2, preparing terminator solution B

Sequentially adding benzene, a disproportionated rosin emulsifier and an anti-aging agent in the stirring process;

s3, mixing

Mixing the terminating agent A liquid and the terminating agent B liquid at 40-45 ℃ and stirring.

Has the advantages that: the terminator is prepared by liquid A and liquid B, and when the liquid B is prepared, disproportionated rosin and the anti-aging agent are dissolved by using benzene as a solvent. Then mixing with the liquid A to form stable terminating agent emulsion.

Further, the polymerization comprises the steps of:

s1, adding the oil phase and the water phase in sequence, stirring, and adding the emulsifier;

s2, adding an initiator and ammonia water;

s3, when the specific gravity of the latex reaches more than 1.10, adding the latex into a termination kettle, deeply turning for 8-12 hours, and adding a termination agent;

and S4, adding an antifreezing agent.

Has the advantages that: the ammonia water is added during polymerization, so that the effects of regulating the pH value, promoting the reaction to be continuously carried out and keeping the emulsion stable can be achieved.

Further, the antifreeze is urea solution.

Has the advantages that: good effect, low price and convenient preparation.

Further, the initiator is added in several portions.

Has the advantages that: the initiator is added for a plurality of times, so that the polymerization reaction is continuously and stably carried out.

Further, the oil phase preparation step comprises the steps of adding a regulator into chloroprene, and adding a disproportionated rosin emulsifier after the regulator is dissolved.

Has the advantages that: the gel and sol content can be initially influenced by the addition of the regulator.

Further, an activator is added to the initiator.

Has the advantages that: the addition of the activator reduces the activation of the reaction to promote the generation of free radicals, facilitating the initiation of the polymerization reaction.

Further, the addition amount of the regulator is 0.3 to 0.6%.

Has the advantages that: the molecular weight of the polymer is adjusted by the amount of the regulator, and the proper molecular weight has good strength. Too much or too little directly affects the strength properties in use.

Detailed Description

The following is further detailed by way of specific embodiments:

table 1 shows the composition settings of the raw materials in examples 1-6, the units are parts by weight:

TABLE 1

The following will describe in detail a method for producing a high gel type adhesive polychloroprene latex, taking example 1 as an example.

A preparation method of high-gel bonding neoprene latex comprises the following steps:

A. preparation of aqueous phase

The soft water is measured in the water phase preparation tank, and the sodium hydroxide (caustic soda liquid), the sodium carbonate and the nonionic emulsifier are sequentially added under stirring, in this embodiment, the nonionic emulsifier is polyoxyethylene ether emulsifier solution, and in addition, polyoxyethylene fatty alcohol ether emulsifier can also be selected. And meanwhile, circulating by using a pump to completely dissolve the substances, and then sampling and analyzing until the substances are qualified, namely, the substances in the solution are completely dissolved for later use.

And starting a water phase pump to convey the qualified water phase liquid into a water phase metering tank, closing the water phase feeding cock and stopping the pump when the required dosage is reached, heating to 26-30 ℃ by using steam, and then supplementing dilution water (including steam condensate water).

B. Oil phase preparation

Pressing chloroprene into the oil phase preparation tank by nitrogen, then starting stirring, heating to 16-18 ℃, adding a regulator D for dissolving for 15 minutes, and then adding disproportionated rosin for dissolving for 20 minutes.

C. Preparation of auxiliary agent

C1, initiator preparation

First initiator:

potassium persulfate solution: in a clean preparation barrel, metering soft water, heating to 30-38 ℃, adding potassium persulfate, stirring and dissolving completely for later use.

Sodium sulfite solution: in a clean preparation barrel, soft water is measured and sodium sulfite is added at normal temperature, and the mixture is stirred and dissolved completely for later use.

Potassium ferrocyanide solution: in a clean preparation barrel, soft water is measured well, potassium ferrocyanide is added at normal temperature, and the mixture is stirred and dissolved completely for later use.

A second initiator:

in a clean preparation barrel, metering soft water, heating to 30-38 ℃, adding potassium persulfate, and stirring to dissolve completely for later use.

Third initiator:

in a clean preparation barrel, metering soft water, heating to 30-38 ℃, adding potassium persulfate, and stirring to dissolve completely for later use.

Potassium ferrocyanide solution: and (4) metering soft water, adding potassium ferrocyanide at normal temperature, and stirring to dissolve completely for later use.

C2, preparation of a terminator:

preparing a terminator solution B: in a clean preparation barrel, benzene is measured, and then disproportionated rosin and an anti-aging agent are sequentially added, wherein in the embodiment, the anti-aging agent is 2, 6-di-tert-butyl-4-methylphenol, and is stirred and dissolved completely for later use.

Preparation of a terminator solution A: adding soft water into the preparation tank, stirring, heating to 40-45 deg.C, adding sodium hydroxide (liquid alkali), and dissolving for 20 min.

Mixing the first solution and the second solution at 40-45 deg.C, stirring, emulsifying for 40-60 min, and keeping the temperature at 40-45 deg.C.

C3, antifreeze agent preparation

In a clean preparation barrel, metering soft water, adding urea when the temperature is raised to 50-60 ℃, and stirring to dissolve completely for later use.

C4, emulsifier preparation

Preparing a polyoxyethylene ether emulsifier solution: in a clean preparation barrel, metering soft water, heating to 60-80 ℃, adding a polyoxyethylene ether emulsifier, and stirring to dissolve completely for later use.

D. Polymerisation

After the equipment, instruments and instruments are checked to be intact, firstly discharging an oil phase, then discharging a water phase, timing and stirring for 10 minutes, then adding a polyoxyethylene ether emulsifier solution into a polymerization kettle, emulsifying for 20 minutes, controlling the temperature in the kettle to be 17-24 ℃, measuring the pH value, then adding a first initiator, wherein the temperature in the kettle is lower than 20 ℃, adding industrial ammonia water (3-5%), controlling the temperature at the early stage to be 17-19 ℃, measuring the specific gravity every 1.5 hours at the early stage, observing the reaction condition in the kettle by an operator when the specific gravity reaches 1.060, and adding a second initiator, a third initiator and the industrial ammonia water if the polymerization speed in the polymerization kettle is low. The second initiator is added in the middle of the reaction, the reaction speed is relatively high, the polymerization speed can be maintained only by using potassium persulfate, and the potassium persulfate ferrocyanide is used in combination for maintaining the polymerization speed because the chloroprene monomer is less when the third initiator is added.

The specific gravity was measured every 0.5 hour at a temperature of 19 to 22 ℃ in the middle and late stages of the polymerization. The method comprises the steps of adjusting saline water at the temperature of 15 ℃ below zero, controlling the polymerization temperature, sampling and analyzing the total solid content when the specific gravity reaches more than 1.10, putting the mixture into a termination kettle for deep rotation, wherein deep rotation refers to deep conversion, and means further polymerizing residual chloroprene monomers under the condition of thermal insulation, wherein the deep rotation temperature is 25-30 ℃, deep rotation is 10 hours, recording every 30 minutes, taking a sample before termination to detect the total solid content, adding a terminator after the deep rotation is qualified, stirring for 40 minutes, adding an antifreezing agent when the content of free sodium hydroxide is detected by sampling and is more than 0.2%, specifically selecting a urea solution as the antifreezing agent in the embodiment, stirring for 20 minutes, putting the urea solution into a storage tank, and packaging.

The polymerization process is as follows:

the polymerization reaction uses potassium persulfate as an initiator, sodium sulfite as a reducing agent to form a redox reaction initiation system, potassium ferrocyanide is added as an activating agent to reduce the reaction activation energy and promote the generation of free radicals, an initiator free radical R is formed, and the polymerization reaction is initiated, wherein the reaction can be simply expressed as:

R°+M→RM°

RM°+M→RM2°

……

RMn-1°+M→RMn°

in the formula, M is a chloroprene monomer.

To fully illustrate the excellent properties of the high gel type adhesive polychloroprene latexes prepared in examples 1-6, a further illustration is given of the 3 sets of comparative examples 1-3:

comparative example 1 is: domestic similar neoprene latex products (model: SN 5042).

Comparative example 2 is: foreign neoprene latex products of the same type (model: C84).

Comparative example 3 is: the difference from example 1 is that: and adding a low-molecular emulsifier in the water phase preparation in the step A.

The experimental tests were carried out for the above examples 1 to 6 and comparative examples 1 to 3, and the test methods and results are shown in the following table 2:

the viscosity was measured according to GB2956-82 "methods for measuring viscosity of synthetic latex".

The surface tension was measured according to GB2960-82 "method for measuring surface tension of synthetic latex".

And (3) measuring the peel strength: according to GB532-82 method for measuring adhesion strength of vulcanized rubber and fabrics.

TABLE 2

	Viscosity (mPa.s)	Surface tension (N/m 10)-3)	Peel strength (N/cm)
				Example 1	23.0	39.5	63.2
Example 2	21.8	38.2	62.3
				Example 3	20.5	39.2	61.5
Example 4	22.4	37.5	65.4
				Example 5	21.5	38.0	64.1
Example 6	20.3	37.8	63.6
				Comparative example 1	20.6	38.6	58.2
Comparative example 2	22.6	39.4	61.3
				Comparative example 3	19.2	36.6	54.2

From the above experimental results, it can be seen that:

1. the highly gelled polychloroprene latexes produced in examples 1-6 had high viscosity, high surface tension, and high peel strength. In particular, the properties of the polychloroprene latex obtained in example 1 exceed those of comparative example 2 (a foreign polychloroprene latex of the same type).

2. In contrast, in comparative example 3, compared with the polychloroprene latexes of examples 1 to 6, the low molecular weight emulsifier is used in the preparation of the aqueous phase, so that the prepared polychloroprene latex has a short bonding time due to the migration of low molecules, and the viscosity, the apparent tension and the peel strength of the polychloroprene latex are reduced.

The foregoing is merely an example of the present invention and common general knowledge of known specific structures and features of the embodiments is not described herein in any greater detail. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent.