阅读说明：本技术 一种羧基改性pva产品及生产工艺 (Carboxyl modified PVA product and production process thereof ) 是由 罗来兵 方乐 于 2021-07-23 设计创作，主要内容包括：本发明公开了一种羧基改性PVA产品,由单体、甲醇、引发剂和碱液为原料制得,所述单体为醋酸乙烯酯和第二共聚单体,所述第二共聚单体为衣康酸。本发明采用了二元羧酸中的衣康酸作为共聚原料,同时引入甲醇作为聚合的溶剂,解决了二元羧酸与醋酸乙烯的相溶性问题,由此得到了羧基含量能够满足要求的羧基改性PVA产品羧基改性PVA产品及生产工艺,本发明制备的羧基改性PVA产品,醇解度86.0～90.0mol％、4％水溶液粘度20～30mPa·s(20℃)、衣康酸含量0.5～1.0mol％的羧基改性聚乙烯醇产品。(The invention discloses a carboxyl modified PVA product which is prepared from monomers, methanol, an initiator and alkali liquor as raw materials, wherein the monomers are vinyl acetate and a second comonomer, and the second comonomer is itaconic acid. The invention adopts itaconic acid in dicarboxylic acid as copolymerization raw material, and simultaneously introduces methanol as polymerization solvent, thus solving the problem of intermiscibility of dicarboxylic acid and vinyl acetate, and obtaining carboxyl modified PVA product with carboxyl content capable of meeting the requirement and the production process thereof.)

1. A carboxyl modified PVA product is characterized by being prepared from monomers, methanol, an initiator and alkali liquor serving as raw materials, wherein the monomers are vinyl acetate and a second comonomer, and the second comonomer is itaconic acid.

2. The carboxyl group-modified PVA product of claim 1, wherein the initiator is a solution of azobisisobutyronitrile, and the purity of the initiator is 99.5%.

3. Process for the production of carboxyl modified PVA products according to claims 1 to 2, characterized in that it comprises the following steps:

s01: adopting two serially connected kettles for continuous polymerization, preparing azodiisobutyronitrile solution and itaconic acid solution with specified concentration before the polymerization reaction starts, introducing warm water into a polymerization kettle jacket to raise the temperature of the polymerization kettle to 60 ℃, starting the polymerization kettle for stirring, preheating vinyl acetate, methanol and itaconic acid solution by a preheater, adding the preheated vinyl acetate, methanol and itaconic acid solution into a first polymerization kettle, and directly adding the initiator solution into the polymerization kettle without passing through the preheater;

s02: opening a discharge valve of the first polymerization kettle when the liquid level of the first polymerization kettle reaches a specified height, continuously adding vinyl acetate, methanol, itaconic acid solution and initiator solution according to continuous polymerization conditions, wherein the residence time of the first polymerization kettle is 5 hours, and delivering the PVAc solution discharged from the first polymerization kettle to a second polymerization kettle;

s03: when the PVAc solution of the first polymerization kettle reaches the second polymerization kettle, adding itaconic acid solution to the second polymerization kettle according to the specified flow, and starting the polymerization tower after the liquid level of the second polymerization kettle reaches the specified height;

s04: removing vinyl acetate monomer from the polymerization-integration tower, adjusting the polymer concentration to a specified value, and sending the tower kettle resin solution to a resin tank;

s05: the concentration of the prepared alkali solution is 14-16g/L, the alcoholysis kettle is washed by methanol, warm water with specified temperature is introduced into a jacket of the alcoholysis kettle, the PVAc resin solution is added into the alcoholysis kettle through a preheater, and meanwhile, an alkali solution is added for alcoholysis reaction;

s06: and after the alcoholysis reaction is finished, conveying the reaction product to an intermediate tank, adding alcoholysis waste liquid to preliminarily wash the reaction kettle, and then performing subsequent liquid removal, drying and packaging.

4. The process for producing carboxyl modified PVA products according to claim 3, wherein the temperature of the alcoholysis reaction is 40 ℃ and the reaction time of the alcoholysis reaction is as follows: 1-3 h, wherein in the alcoholysis reaction, the concentration of PVAc: 25-30% and water content: 0.1-1.0% alkali molar ratio: 0.001-0.02 + 2X itaconic acid content (mol%)/100.

5. The process for producing a carboxyl group-modified PVA product according to claim 3, wherein in step S01, vinyl acetate/methanol (by volume) initially charged into the first polymerization vessel is 77.3/22.7, itaconic acid/vinyl acetate (by mass) is 1/0.314, and initiator/vinyl acetate (by mass) is 0.02 to 0.025.

6. The process of claim 3, wherein in step S02, the vinyl acetate/methanol (by volume) continuously fed into the first polymerization vessel is 77.3/22.7, the itaconic acid/vinyl acetate (by mass) is 1/0.627, and the initiator/vinyl acetate (by mass) is 0.02-0.025.

7. The process for producing a carboxyl group-modified PVA product according to claim 3, wherein the itaconic acid solution has a purity of 99.5%.

Technical Field

The invention relates to the technical field of polyvinyl alcohol, in particular to a carboxyl modified PVA product and a production process thereof.

Background

The carboxyl modified polyvinyl alcohol is an important functional polymer, after carboxyl with strong hydrophilicity and high reaction activity is introduced into a PVA molecular chain, the carboxyl modified polyvinyl alcohol has the properties of the conventional polyvinyl alcohol, and the newly introduced carboxyl can endow the polyvinyl alcohol molecule with some special performances such as high water solubility and crosslinking reactivity, so that the carboxyl modified PVA has excellent crosslinking reactivity, water solubility, dispersibility, rheological property, anti-skinning performance and low foaming performance, has good application prospect, and can be widely applied to the fields of special paper, adhesives, cement slurry for well cementation in oil fields and the like.

PVA is a water-soluble environment-friendly high molecular polymer, and generally is dissolved to form an aqueous solution when in use, but the dissolving process of a high molecular substance is difficult, so that the improvement of the water solubility of the PVA is very significant, in the past, monocarboxylic acid such as acrylic acid, methacrylic acid, crotonic acid and the like or esters thereof are copolymerized with vinyl acetate, and then the copolymer is subjected to alcoholysis to obtain carboxyl modified PVA, and the method is easy to generate lactone rings, so that the carboxyl content in the product is reduced. In addition, some researchers have prepared carboxyl-modified PVA with dicarboxylic acids as comonomers. Representative comonomers include maleic acid, fumaric acid, Itaconic Acid (IA), and esters thereof. Maleic acid, fumaric acid and itaconic acid are not directly utilized due to poor solubility in VAc, but are used for copolymerization with vinyl acetate after being converted into methyl esters. The problem with this approach is that PVA is poorly soluble.

Disclosure of Invention

The invention aims to solve the problem of the compatibility of dicarboxylic acid and vinyl acetate by adopting itaconic acid in dicarboxylic acid as a copolymerization raw material and introducing methanol as a polymerization solvent, thereby obtaining a carboxyl modified PVA product with the carboxyl content meeting the requirement and a production process thereof so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a carboxyl modified PVA product is prepared from monomers, methanol, an initiator and alkali liquor as raw materials, wherein the monomers are vinyl acetate and a second comonomer, and the second comonomer is itaconic acid.

Preferably, the initiator is azobisisobutyronitrile solution, and the purity of the initiator is 99.5%.

A production process of a carboxyl modified PVA product comprises the following steps:

s01: adopting two serially connected kettles for continuous polymerization, preparing azodiisobutyronitrile solution and itaconic acid solution with specified concentration before the polymerization reaction starts, introducing warm water into a polymerization kettle jacket to raise the temperature of the polymerization kettle to 60 ℃, starting the polymerization kettle for stirring, preheating vinyl acetate, methanol and itaconic acid solution by a preheater, adding the preheated vinyl acetate, methanol and itaconic acid solution into a first polymerization kettle, and directly adding the initiator solution into the polymerization kettle without passing through the preheater;

s02: opening a discharge valve of the first polymerization kettle when the liquid level of the first polymerization kettle reaches a specified height, continuously adding vinyl acetate, methanol, itaconic acid solution and initiator solution according to continuous polymerization conditions, wherein the residence time of the first polymerization kettle is 5 hours, and delivering the PVAc solution discharged from the first polymerization kettle to a second polymerization kettle;

s03: when the PVAc solution of the first polymerization kettle reaches the second polymerization kettle, adding itaconic acid solution to the second polymerization kettle according to the specified flow, and starting the polymerization tower after the liquid level of the second polymerization kettle reaches the specified height;

s04: removing vinyl acetate monomer from the polymerization-integration tower, adjusting the polymer concentration to a specified value, and sending the tower kettle resin solution to a resin tank;

s05: the concentration of the prepared alkali solution is 14-16g/L, the alcoholysis kettle is washed by methanol, warm water with specified temperature is introduced into a jacket of the alcoholysis kettle, the PVAc resin solution is added into the alcoholysis kettle through a preheater, and meanwhile, an alkali solution is added for alcoholysis reaction;

s06: and after the alcoholysis reaction is finished, conveying the reaction product to an intermediate tank, adding alcoholysis waste liquid to preliminarily wash the reaction kettle, and then performing subsequent liquid removal, drying and packaging.

Preferably, the temperature of the alcoholysis reaction is 40 ℃, and the reaction time of the alcoholysis reaction is as follows: 1-3 h, wherein in the alcoholysis reaction, the concentration of PVAc: 25-30% and water content: 0.1-1.0%, and the molar ratio of alkali: 0.001-0.02 + 2X itaconic acid content (mol%)/100.

Preferably, in step S01, the vinyl acetate/methanol (volume) initially charged into the first polymerization vessel is 77.3/22.7, the itaconic acid/vinyl acetate (mass) is 1/0.314, and the initiator/vinyl acetate (mass) is 0.02 to 0.025.

Preferably, in step S02, the vinyl acetate/methanol (volume) continuously added into the first polymerization vessel is 77.3/22.7, the itaconic acid/vinyl acetate (mass) is 1/0.627, and the initiator/vinyl acetate (mass) is 0.02-0.025.

Advantageous effects

The invention provides a carboxyl modified PVA product and a production process thereof, and the product has the following beneficial effects:

the invention adopts itaconic acid in dicarboxylic acid as copolymerization raw material, and simultaneously introduces methanol as polymerization solvent, thus solving the problem of intermiscibility of dicarboxylic acid and vinyl acetate, and obtaining carboxyl modified PVA product with carboxyl content capable of meeting the requirement and the production process thereof.

Detailed Description

The technical solution of the present patent will be described in further detail with reference to the following embodiments.

A carboxyl modified PVA product is prepared from monomers, methanol, an initiator and alkali liquor as raw materials, wherein the monomers are vinyl acetate and a second comonomer, and the second comonomer is itaconic acid.

The initiator is azobisisobutyronitrile solution, and the purity of the initiator is 99.5%.

A production process of a carboxyl modified PVA product comprises the following steps:

s01: adopting two serially connected kettles for continuous polymerization, preparing azodiisobutyronitrile solution and itaconic acid solution with specified concentration before the polymerization reaction starts, introducing warm water into a polymerization kettle jacket to raise the temperature of the polymerization kettle to 60 ℃, starting the polymerization kettle for stirring, preheating vinyl acetate, methanol and itaconic acid solution by a preheater, adding the preheated vinyl acetate, methanol and itaconic acid solution into a first polymerization kettle, and directly adding the initiator solution into the polymerization kettle without passing through the preheater;

s02: opening a discharge valve of the first polymerization kettle when the liquid level of the first polymerization kettle reaches a specified height, continuously adding vinyl acetate, methanol, itaconic acid solution and initiator solution according to continuous polymerization conditions, wherein the residence time of the first polymerization kettle is 5 hours, and delivering the PVAc solution discharged from the first polymerization kettle to a second polymerization kettle;

s03: when the PVAc solution of the first polymerization kettle reaches the second polymerization kettle, adding itaconic acid solution to the second polymerization kettle according to the specified flow, and starting the polymerization tower after the liquid level of the second polymerization kettle reaches the specified height;

s04: removing vinyl acetate monomer from the polymerization-integration tower, adjusting the polymer concentration to a specified value, and sending the tower kettle resin solution to a resin tank;

s05: the concentration of the prepared alkali solution is 14-16g/L, the alcoholysis kettle is washed by methanol, warm water with specified temperature is introduced into a jacket of the alcoholysis kettle, the PVAc resin solution is added into the alcoholysis kettle through a preheater, and meanwhile, an alkali solution is added for alcoholysis reaction;

s06: and after the alcoholysis reaction is finished, conveying the reaction product to an intermediate tank, adding alcoholysis waste liquid to preliminarily wash the reaction kettle, and then performing subsequent liquid removal, drying and packaging.

The temperature of the alcoholysis reaction is 40 ℃, and the reaction time of the alcoholysis reaction is as follows: 1-3 h, wherein in the alcoholysis reaction, the concentration of PVAc: 25-30% and water content: 0.1 to 1.0%

Molar ratio of alkali: 0.001-0.02 + 2X itaconic acid content (mol%)/100.

In step S01, the vinyl acetate/methanol (volume) initially added to the first polymerizer is 77.3/22.7, the itaconic acid/vinyl acetate (mass) is 1/0.314, and the initiator/vinyl acetate (mass) is 0.02-0.025.

In step S02, the vinyl acetate/methanol (by volume) continuously added to the first polymerization vessel is 77.3/22.7, the itaconic acid/vinyl acetate (by mass) is 1/0.627, and the initiator/vinyl acetate (by mass) is 0.02-0.025.

The invention adopts itaconic acid in dicarboxylic acid as copolymerization raw material, and simultaneously introduces methanol as polymerization solvent, thus solving the problem of intermiscibility of dicarboxylic acid and vinyl acetate, and obtaining carboxyl modified PVA product with carboxyl content capable of meeting the requirement and the production process thereof.

In the description of the present invention, it is to be understood that the terms "opening," "upper," "lower," "thickness," "top," "middle," "length," "inner," "peripheral," and the like are used in an orientation or positional relationship that is merely for convenience in describing and simplifying the description, and do not indicate or imply that the referenced component or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present invention.

In the description herein, references to the description of "one embodiment," "an example," "a specific example," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.