CN108017738B

CN108017738B - Environment-friendly aqueous composite terminator

Info

Publication number: CN108017738B
Application number: CN201711226175.4A
Authority: CN
Inventors: 陈军民; 宋芬
Original assignee: Jining Kendray Chemical Technology Co Ltd
Current assignee: Jining Kendray Chemical Technology Co Ltd
Priority date: 2017-11-29
Filing date: 2017-11-29
Publication date: 2020-03-31
Anticipated expiration: 2037-11-29
Also published as: CN108017738A

Abstract

An environment-friendly aqueous composite terminator is prepared from isopropylhydroxylamine, diethylhydroxylamine and sodium perchlorate through adding deionized water to reactor, adding sodium perchlorate to deionized water, dissolving potassium perchlorate, adding isopropylhydroxylamine, diethylhydroxylamine or their mixture, mixing, and discharging. The environment-friendly water-based composite terminator can terminate the reaction in time when the polymerization reaction reaches a certain conversion rate, and can improve the whiteness and aging whiteness of the synthetic PVC resin product.

Description

Environment-friendly aqueous composite terminator

Technical Field

The invention relates to the technical field of fine chemical engineering, in particular to an environment-friendly aqueous composite terminator.

Background

The aqueous suspension polymerization is the main method for synthesizing PVC resin, the dispersing agent, buffering agent, initiator, pH value regulator and other assistants and vinyl chloride monomer reaction raw material are added into the aqueous solution system, the reactant is dispersed in high degree under the action of stirring to form stable emulsion, the vinyl chloride monomer is dispersed in tiny liquid drops by the protective colloid in water, each liquid drop is equivalent to a polymerization system, the initiator dissolved in the monomer is decomposed into free radicals at the polymerization temperature to initiate the polymerization of the vinyl chloride monomer, and the whole polymerization process comprises unit reactions such as chain initiation, chain growth, chain termination and the like.

Chain initiation is a reaction in which monomers form free radical reactive centers, typically involving decomposition of the initiator to form primary radicals R; addition of the primary radical to VCM to form the monomeric radical CH₂C, HCI; in the chain growth stage, monomer molecules are continuously added to grow chains to form macromolecules on the basis of chain initiation to form monomer free radicals; the chain termination stage involves the termination of a chain by free radical interaction, and the interaction of two growing living chains by free radicals, so that the termination reaction of free radical polymerization is a bimolecular reaction, with both coupling and disproportionation. The monomer concentration is lower in the later stage of the polymerization reaction process, if the reaction is automatically terminated, the termination is mainly terminated by double-radical disproportionation, and two large PVC free radical molecules meet to form a saturated macromolecule to be terminated; the other is the termination of the unsaturation with the double bond, which results in an increase in the production of PVC of small molecular mass, PVC with branched chains, PVC products with allyl chloride structure. PVC with the molecular structure has extremely poor thermal stability, particularly allyl chloride exists on the molecular chain, the PVC has high activity, hydrogen chloride is easy to remove under the heating condition, the structure of conjugated polyene is formed, and HC removed in the initial stageAnd l is a catalyst for continuous thermal decomposition of a polyvinyl chloride polymer chain, so that once dehydrochlorination reaction is started, further reaction is easier, thermal aging of a PVC resin product is caused, and the yellow index is increased, so that whiteness is reduced. In addition, under the action of heat or light, the homolytic cleavage of C-Cl bonds occurs to generate polymer free radicals R; because of the reactivity of the free radicals, the further reactions between molecules or in molecules can be carried out to obtain stability, and particularly under the condition of the existence of oxygen, the oxidation reaction of the free radicals can easily occur to generate oxidation free radicals RO and peroxidation free radicals ROO; thereby further promoting the molecular crosslinking of the polyvinyl chloride, and causing the polyvinyl chloride to age. Therefore, the addition of the terminator must be started when the polymerization reaction reaches the set end point, the end point of the polymerization reaction is selected to be about 70-85% of the conversion rate, in order to improve the stability of the PVC product, the free radicals and residual initiators remained in the resin need to be eliminated, which is also an important basis for designing the composition formula of the terminator, and the good terminator can rapidly terminate and inactivate the residual initiators, primary free radicals, monomer free radicals and growing active chain free radicals in the kettle, so that the undesired reaction behavior can be immediately stopped, and the good PVC molecular structure with stability can be obtained.

The raw materials of the conventional terminating agents have certain defects, such as: bisphenol A is an ideal polymerization terminator, and although the kettle pressure is slowly reduced after the bisphenol A is added, the practice proves that the yield is not obviously changed, the reaction is basically stopped, the thermal property of the product is obviously improved, and the whiteness is slightly reduced. Acetone Amidothiourea (ATSC) terminated the polymerization faster and more thoroughly than bisphenol a. But it has a single action, only plays a terminating role without a heat stabilizing effect, and is relatively expensive.

The terminator which is compounded by a plurality of antioxidants based on ATSC, such as Chinese patents CN101921354A, CN101735357A, CN1657546A, CN1654486A and the like, still has the problems of high cost, use of ATSC substances with higher toxicity and the like. In addition, there are other types of terminators, such as: chinese patent CN1649913A discloses a chain termination method for PVC polymerization, in which free nitroxyl and phenolic antioxidant are compounded as a terminator. In the method for aqueous suspension polymerization of vinyl chloride disclosed in chinese patent CN1501945A, a stable free radical of nitroxide type is used as a polymerization terminator, or a compound of a stable free radical of nitroxide type and diethylhydroxylamine is used as a terminator. Chinese patent CN201110380532.9 discloses a preparation method of a polyvinyl chloride resin terminator, which comprises the steps of adding an organic solvent into an antioxidant product taking 2, 6-di-tert-butyl-4- (1-phenylethyl) phenol as a main product, fully stirring to prepare a liquid antioxidant product capable of meeting the fluidity requirement, and compounding the liquid antioxidant product with a functional antioxidant to prepare an oil-soluble, compound and liquid terminator product. The terminating agents disclosed in these patents also have the disadvantages of complicated preparation process or high cost.

Disclosure of Invention

The first purpose of the invention is to overcome the defects of the prior art and provide an environment-friendly water-based composite terminator which can terminate the reaction in time when the polymerization reaction reaches a certain conversion rate and can improve the whiteness and the aging whiteness of the synthetic PVC resin product.

The second purpose of the invention is to provide the preparation method of the environment-friendly aqueous composite terminator, and the method has the characteristics of simple production process, easily available raw materials, low product use cost and convenience for industrial popularization and application.

The environment-friendly aqueous composite terminator comprises 80-100 parts by mass of isopropyl hydroxylamine, 0-15 parts by mass of diethyl hydroxylamine and 5-20 parts by mass of sodium perchlorate, wherein the isopropyl hydroxylamine, the diethyl hydroxylamine and the sodium perchlorate are uniformly mixed by deionized water, and the deionized water accounts for 50-83 parts by mass.

Further, the diethylhydroxylamine content used was 85% or 98%.

Further, the mixing temperature is 25-35 ℃.

The invention relates to a preparation method of an environment-friendly water-based composite terminator, which comprises the following specific steps:

(1) adding deionized water into a reaction kettle;

(2) heating deionized water in a reaction kettle to 20-50 ℃;

(3) adding sodium perchlorate into the heated deionized water, adding isopropyl hydroxylamine, diethyl hydroxylamine or a mixture of the isopropyl hydroxylamine and the diethyl hydroxylamine after the potassium perchlorate is dissolved, uniformly mixing and discharging.

The environment-friendly water-based composite terminator can terminate the reaction in time when the polymerization reaction reaches a certain conversion rate, and can improve the whiteness and aging whiteness of the synthetic PVC resin product.

Detailed Description

Example 1: adding 70 parts of deionized water into a reaction kettle, heating to 25-30 ℃, adding 15 parts of sodium perchlorate, adding 100 parts of 15% isopropyl hydroxylamine after dissolution, uniformly mixing and discharging.

Example 2: adding 70 parts of deionized water into a reaction kettle, heating to 25-30 ℃, adding 15 parts of sodium perchlorate, adding 60 parts of 15% isopropyl hydroxylamine and 6 parts of 98% diethyl hydroxylamine after dissolution, uniformly mixing, and discharging.

Example 3: adding 70 parts of deionized water into a reaction kettle, heating to 25-30 ℃, adding 15 parts of sodium perchlorate, adding 40 parts of 15% isopropyl hydroxylamine and 9 parts of 98% diethyl hydroxylamine after dissolution, uniformly mixing, and discharging.

Example 4: adding 70 parts of deionized water into a reaction kettle, heating to 25-30 ℃, adding 15 parts of sodium perchlorate, adding 16 parts of 98% diethylhydroxylamine after dissolution, uniformly mixing, and discharging.

The effect evaluation test and the result of the invention are as follows: according to the production process conditions of PVC for transparent hard products and the like prepared by a suspension polymerization method, the PVC is polymerized for 7 hours at 57 ℃, then the polymer material is taken and dried for ten minutes at 160 ℃, and then the whiteness is measured by a whiteness meter according to GB/T15595 ion 2008, and the experimental results are as follows:

from the aging whiteness, the terminator of the embodiment of the invention is added, the aging whiteness of all embodiments is 85.1-89.2, which is more than 78% of the index of national standard superior products. The effect is obvious from the termination effect, and the PVC terminator is an excellent PVC terminator.

The foregoing shows and describes the general principles and features of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The preparation method of the environment-friendly water-based composite terminator is characterized by comprising the following steps of:

(1) adding 50-83 parts by mass of deionized water into a reaction kettle;

(2) heating deionized water in a reaction kettle to 20-50 ℃;

(3) adding 5-20 parts by mass of sodium perchlorate into the heated deionized water, adding 80-100 parts by mass of isopropyl hydroxylamine, 0-15 parts by mass of diethyl hydroxylamine or a mixture of the isopropyl hydroxylamine and the diethyl hydroxylamine with the concentration of 15% after the potassium perchlorate is dissolved, uniformly mixing and discharging.

2. The method for preparing the environment-friendly aqueous composite terminator according to claim 1, characterized in that: the diethylhydroxylamine content used was 85% or 98%.

3. The method for preparing the environment-friendly aqueous composite terminator according to claim 1, characterized in that: the mixing temperature is 25-35 ℃.