WO2021072942A1 - Preparation method for zinc tartrate and application thereof in stabilizer - Google Patents

Abstract

The present invention provides a preparation method for zinc tartrate (I) shown as a structural formula (I). The method comprises: first, reacting tartaric acid (II) with sodium hydroxide to prepare sodium tartrate (III), and then reacting the prepared sodium tartrate (III) with zinc sulfate heptahydrate to obtain the zinc tartrate (I). The prepared zinc tartrate (I) can be added into a stabilizer, and the addition amount of the zinc tartrate (I) is 5.5-6.5 wt%. In the present invention, the zinc content of the zinc tartrate (I) is 26.2%, and the initial whiteness of the product can be significantly improved.

Description

A preparation method of zinc tartrate and its application in stabilizer Technical field

The invention belongs to the field of stabilizer preparation, and specifically relates to a method for preparing zinc tartrate and its application in stabilizers.

Background technique

At present, it can be found in the thermal degradation mechanism of PVC that as a thermal stabilizer of PVC, it must have one or more of the following functions:

①Replace allyl chloride atoms or tertiary chlorine atoms in PVC molecules to eliminate unstable structural factors that cause PVC thermal degradation;

②Neutralize and absorb the HCl released by the thermal degradation of PVC, eliminate or inhibit its autocatalysis on the thermal degradation of PVC;

③Addition to the conjugated polyene sequence generated by the thermal degradation of PVC, blocking its further growth and shortening the conjugated polyene chain;

④ Capture free radicals.

At present, the commonly used heat stabilizers are mainly divided into inorganic lead salts, metal soap salts, organic tin, and organic auxiliary heat stabilizers. Among them, the most commonly used metal soap stabilizer is zinc soap stabilizer. Zinc soap stabilizer can not only neutralize and absorb HCl, but also replace unstable chlorine atoms with carboxylate radicals to eliminate thermal degradation initiation sites, thus slowing down PVC. The removal of HCl can inhibit its initial coloring. However, zinc soap will produce ZnCl ₂ due to the absorption of HCl. The resulting ZnCl ₂ has a strong catalytic effect, which will promote the further dehydrogenation of the polyene sequence, resulting in poor long-term thermal stability, and the ingredients will undergo malignant degradation soon after being heated. The blackening and coking is also known as "zinc burn".

Polyol compound is a commonly used auxiliary heat stabilizer. The polyol compound contains multiple hydroxyl groups, and these hydroxyl groups can ^{form a stable chelate with Zn 2+} , thereby inactivating its catalytic effect on the thermal degradation of PVC. In theory, the more the number of hydroxyl groups contained in the molecule, the more significant its effect of improving long-term thermal stability, but it will also lead to a decrease in its effect of inhibiting initial discoloration.

Most of the zinc salts used in the existing calcium and zinc stabilizers are fatty acid zinc salts, leading to serious zinc burning in the later stage. In order to avoid this phenomenon, it is often necessary to add polyol auxiliary heat stabilizers, such as pentaerythritol, sorbitol and other compounds. .

In zinc soap stabilizers, zinc content is an important factor affecting the initial color of PVC. Most traditional zinc soap stabilizers are monobasic fatty acids, so one molecule of fatty acid zinc requires two molecules of monobasic fatty acid, which leads to the formation of zinc soap The higher the molecular weight, the lower the zinc content. In order to increase the zinc content, the dibasic fatty acid can be used to react with the zinc source, so that only one molecule of fatty acid can generate one molecule of zinc soap with one molecule of zinc source. The fatty acid chain will decrease and the zinc content will increase, thereby achieving an increase. The effect of initial whiteness.

In order to reduce the late "zinc burning" phenomenon of zinc soap stabilizers, the existing zinc soap stabilizers need to add polyol compounds to inhibit the late "zinc burning". The mechanism of the polyol compound is to ^{form a stable chelate compound with Zn 2+} through the hydroxyl group, thereby inactivating its catalytic effect on the thermal degradation of PVC. Therefore, the functional group that plays a key role in the polyol compound only needs to be a hydroxyl group.

Summary of the invention

The present invention starts from the above two aspects, looking for a dibasic acid with hydroxyl group, and tartaric acid (II) is one of them. The molecular formula of tartaric acid (Ⅱ) is C ₄ H ₆ O ₄ , and the structural formula is

It can be seen that tartaric acid (II) has two carboxyl groups and two hydroxyl groups. The zinc tartrate (I) produced is both a zinc dibasic acid and two hydroxyl groups, which means that the zinc tartrate (I) not only has good initial coloring, but also can well inhibit the later "zinc burning". The specific of the present invention The content is as follows:

One of the objectives of the present invention is to provide a structural formula such as (I):

The method for preparing zinc tartrate (I), the technical point is: the method for preparing zinc tartrate (I) is as follows:

Preparation of S1 Sodium Tartrate (Ⅲ): Weigh tartaric acid (Ⅱ) and add it to the Erlenmeyer flask, then slowly add deionized water to it and stir evenly until it appears a white turbid liquid, then weigh the sodium hydroxide and slowly add it to the Erlenmeyer flask Then add deionized water again, stir slowly, then heat and stir until the solution becomes clear, then adjust the pH of the reaction solution to 7 with acid, and stop heating to obtain sodium tartrate (Ⅲ). The specific reaction equation is as follows:

S2 Preparation of zinc tartrate (I): Weigh zinc sulfate heptahydrate and slowly add it to the Erlenmeyer flask described in step S1. The clear reaction liquid in step S1 becomes turbid, and continues to the triangle described in step S1. Deionized water is added to the flask, and the precipitate obtained by stirring while heating is the zinc tartrate (I). The specific reaction equation is as follows:

In some embodiments of the present invention, the weight ratio of tartaric acid (II) and sodium hydroxide in the step S1 is 3 to 3.5:1, the reaction temperature is 70 to 80°C, and the reaction The time is 20-40min.

In some embodiments of the present invention, the acid in the step S1 is a hydrochloric acid solution with a substance concentration of 1 to 3 mol/L.

In some embodiments of the present invention, the weight ratio of step S2 zinc sulfate heptahydrate and tartaric acid (II) is 1.5 to 2.5:1, the reaction temperature is 100 to 120°C, and the reaction The time is 50～70min.

Another object of the present invention is to provide an application of zinc tartrate (I) in a stabilizer. The technical point is: the zinc tartrate (I) is added to the stabilizer, and the addition amount of the zinc tartrate (I) is It is 5.5~6.5wt%.

In some embodiments of the present invention, the stabilizer is composed of calcium stearate, zinc stearate, zinc tartrate (I), zeolite, tris(2-hydroxyethyl) isocyanurate, and maleic acid. It is prepared by mixing di-n-butyl acid, calcium acetylacetonate, n-octadecyl propionate, pentaerythritol, perchlorate, internal lubricant and external lubricant.

In some embodiments of the present invention, the weight ratio of zinc stearate and zinc tartrate (I) is 0-1:1.

Compared with the prior art, the present invention has the following beneficial effects:

1. The method for preparing zinc tartrate (I) of the present invention, wherein the solubility of tartaric acid (II) in water at low temperature is low, and adding water directly to tartaric acid (II) under normal temperature conditions will result in a white turbid liquid, and adding hydroxide After sodium, the two react quickly, the solution becomes clear, and sodium tartrate (Ⅲ), which is easily soluble in water, is formed. The progress of the reaction is determined by measuring the PH value of the clarified liquid. Since the target product zinc tartrate (I) is insoluble in water, the amount of sodium hydroxide must be controlled to avoid excessive sodium hydroxide reacting with zinc sulfate (I) to form hydroxide Zinc precipitation. By adjusting the pH value, add zinc sulfate heptahydrate after reaching 7 to quickly generate zinc tartrate (I) precipitation, and then filter through multiple washings to remove other ions.

2. A preparation method of zinc tartrate (I) according to the present invention, wherein zinc tartrate (I) is used instead of the traditional zinc salt stabilizer and applied in the PVC production formula. The traditional zinc stearate has a molecular weight of 632 and a zinc content of 10.3%, while the molecular weight of zinc tartrate (I) is 249.5. Its zinc content is 26.2%. It can be seen that the zinc dibasic acid proposed in the present invention has a very high Zinc content, which can significantly improve the initial whiteness of the product. Moreover, the zinc tartrate (I) prepared by the present invention also has two hydroxyl groups. When the zinc tartrate (I) absorbs HCl, it will generate ZnCl ₂ and tartaric acid (II). The reaction equation is as follows:

The resulting zinc chloride will promote further dehydrogenation of the PVC long chain, leading to "zinc burning", while another product, tartaric acid (II), is an alkyd compound with two hydroxyl groups, which can form a stable _{compound with ZnCl 2} Chelate (Ⅳ), its reaction equation is:

Description of the drawings

Figure 1 is a flow chart of a method for preparing zinc tartrate (I) of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below, so that those skilled in the art can better understand the advantages and features of the present invention, so as to make a clearer definition of the protection scope of the present invention. The described embodiments of the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without creative work Examples are all within the protection scope of the present invention.

Example 1

A structural formula such as (Ⅰ):

The preparation method of zinc tartrate (Ⅰ) is as follows:

Preparation of S1 Sodium Tartrate (Ⅲ): Weigh 30g of tartaric acid (Ⅱ) and add it to a Erlenmeyer flask, then slowly add deionized water to it and stir evenly until it appears a white turbid liquid, then weigh 9.56g of sodium hydroxide and add slowly Into the conical flask for reaction, add deionized water again, stir slowly, then heat to 75 ℃, stir for 30 minutes, until the solution becomes clear, and then adjust the reaction solution with a hydrochloric acid solution with a concentration of 2mol/L. When the pH reaches 7, the heating is stopped to obtain sodium tartrate (Ⅲ). The specific reaction equation is as follows:

S2 Zinc tartrate (I) preparation: Weigh 57.5g zinc sulfate heptahydrate, and slowly add it to the Erlenmeyer flask described in step S1, the clear reaction liquid in step S1 becomes turbid, and continues to step S1 Add deionized water to the Erlenmeyer flask, heat it to 110°C, and react for 60 minutes. The precipitate obtained is the zinc tartrate (I). The product is taken out, filtered, washed and dried, and the zinc content is determined to be 27.58%. The specific reaction equation is as follows :

An application of zinc tartrate (I) in a stabilizer. Zinc tartrate (I) is added to the stabilizer. The specific formula is shown in Table 1. The mass of the added tartaric acid is 5g.

Example 2

A structural formula such as (Ⅰ):

The preparation method of zinc tartrate (Ⅰ) is as follows:

Preparation of S1 Sodium Tartrate (Ⅲ): Weigh 30g of tartaric acid (Ⅱ) into a Erlenmeyer flask, then slowly add deionized water to it and stir evenly until it appears a white turbid liquid, then weigh 8.57g of sodium hydroxide and add slowly Into the conical flask for reaction, add deionized water again, stir slowly, then heat to 70℃, stir for 40 minutes, until the solution becomes clear, and then adjust the reaction solution with a hydrochloric acid solution with a concentration of 1mol/L. After the pH reaches 7, the heating is stopped to obtain sodium tartrate (Ⅲ). After the product is taken out, filtered, washed and dried, the zinc content is determined to be 26.13%. The specific reaction equation is as follows:

S2 Zinc tartrate (I) preparation: Weigh 45g zinc sulfate heptahydrate, and slowly add it to the Erlenmeyer flask described in step S1, the clear reaction liquid in step S1 becomes turbid, and continues to the step S1 Add deionized water to the Erlenmeyer flask, heat to 100°C, and react for 70 min. The precipitate obtained is the zinc tartrate (I). The specific reaction equation is as follows:

An application of zinc tartrate (I) in a stabilizer. Zinc tartrate (I) is added to the stabilizer. The specific formula is shown in Table 1. The mass of the added tartaric acid is 5g.

Example 3

A structural formula such as (Ⅰ):

The preparation method of zinc tartrate (Ⅰ) is as follows:

Preparation of S1 Sodium Tartrate (Ⅲ): Weigh 30g of tartaric acid (Ⅱ) and add it to a Erlenmeyer flask, then slowly add deionized water to it and stir evenly until it appears a white turbid liquid, then weigh 10g of sodium hydroxide and slowly add it to The reaction is carried out in the Erlenmeyer flask, again adding deionized water, stirring slowly, then heating to 80°C, stirring for 20 minutes, until the solution becomes clear, and then adjusting the pH of the reaction solution with a hydrochloric acid solution with a substance concentration of 3mol/L To 7, stop heating to obtain sodium tartrate (Ⅲ), the specific reaction equation is as follows:

S2 Zinc tartrate (I) preparation: Weigh 75g zinc sulfate heptahydrate, and slowly add it to the Erlenmeyer flask described in step S1, the clear reaction liquid in step S1 becomes turbid, and continues to the step S1 Add deionized water to the Erlenmeyer flask, heat to 120°C, and react for 50 minutes. The precipitate obtained is the zinc tartrate (I). The product is filtered, washed and dried, and the zinc content is determined to be 28.05%. The specific reaction equation is as follows:

An application of zinc tartrate (I) in a stabilizer is to add zinc tartrate (I) to the stabilizer. The specific formula is shown in Table 1. The weight of the added tartaric acid is 5g.

Comparison

As shown in Table 1, add 20g of zinc stearate to prepare a traditional stabilizer.

Table 1 Formula of stabilizer

Experimental example

According to the ratio shown in Table 2, the components of each group were stirred uniformly in a disperser, and then mixed on an open rubber mixing machine at a temperature of 190±2°C and a mixing time of 3 minutes to prepare PVC flakes. The prepared PVC sheet samples were made into 10 small pieces of 16mm×24mm, placed on aluminum foil, and placed in a 401A aging test box at a temperature of 190±1℃. One piece was taken out every 10 minutes to test its yellowness. The results are shown in Table 3:

Table 2 Formula of PVC

raw material	①	②	③	④
PVC	100	100	100	100
Titanium Dioxide	2	2	2	2
ACR	1	1	1	1
Calcium carbonate	10	10	10	10
Processing aids	6	6	6	6
Internal and external lubrication	0.5	0.5	0.5	0.5
Example 1 Stabilizer	2.7	-	-	-
Example 2 Stabilizer	-	2.7	-	3
Example 2 Stabilizer	-	-	2.7	-
Comparative stabilizer	-	-	-	-

Table 3 Yellowness test results

Time/min	10	20	30	40	50	60	70	80	90	100
①	4.08	8.12	12.35	16.98	21.25	27.64	34.58	40.14	48.27	56.14
②	4.06	8.10	12.33	17.01	21.25	27.55	34.55	40.16	48.25	To
③	4.07	8.14	12.37	16.88	20.98	27.71	33.98	40.91	48.35	To
④	4.96	9.03	13.28	17.59	22.14	29.48	36.47	42.97	50.15	58.46

It can be seen from Table 3 that the zinc tartrate (I) prepared by the method of the present invention can significantly improve the initial whiteness of PVC products and can effectively reduce the occurrence of "zinc burn" phenomenon, so the present invention has great prospects.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand The technical solution of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solution of the present invention.

Claims (7)

1. A structural formula such as (Ⅰ):

   

   The method for preparing zinc tartrate (I) is characterized in that: the method for preparing zinc tartrate (I) is as follows:

   Preparation of S1 Sodium Tartrate (Ⅲ): Weigh tartaric acid (Ⅱ) and add it to the Erlenmeyer flask, then slowly add deionized water to it and stir evenly until it appears a white turbid liquid, then weigh the sodium hydroxide and slowly add it to the Erlenmeyer flask Then add deionized water again, stir slowly, then heat and stir until the solution becomes clear, then adjust the pH of the reaction solution to 7 with acid, and stop heating to obtain sodium tartrate (Ⅲ). The specific reaction equation is as follows:

   

   S2 Preparation of zinc tartrate (I): Weigh zinc sulfate heptahydrate and slowly add it to the Erlenmeyer flask described in step S1. The clear reaction liquid in step S1 becomes turbid, and continues to the triangle described in step S1. Deionized water is added to the flask, and the precipitate obtained by stirring while heating is the zinc tartrate (I). The specific reaction equation is as follows:

   
2. The method for preparing zinc tartrate (I) according to claim 1, wherein the weight ratio of tartaric acid (II) and sodium hydroxide in step S1 is 3 to 3.5:1, and The reaction temperature is 70-80°C, and the reaction time is 20-40 min.
3. The method for preparing zinc tartrate (I) according to claim 1, wherein the acid in step S1 is a hydrochloric acid solution with a substance concentration of 1 to 3 mol/L.
4. The method for preparing zinc tartrate (I) according to claim 1, wherein the weight ratio of zinc sulfate heptahydrate and tartaric acid (II) in step S2 is 1.5 to 2.5:1, and The reaction temperature is 100-120°C, and the reaction time is 50-70 min.
5. An application of zinc tartrate (I) in a stabilizer, characterized in that: the zinc tartrate (I) is added to the stabilizer, and the addition amount of the zinc tartrate (I) is 5.5-6.5 wt%.
6. The use of zinc tartrate (I) in a stabilizer according to claim 5, wherein the stabilizer is composed of calcium stearate, zinc stearate, zinc tartrate (I), zeolite, and three (2-Hydroxyethyl) isocyanurate, di-n-butyl maleate, calcium acetylacetonate, n-stearyl propionate, pentaerythritol, perchlorate, internal lubricant and external lubricant are mixed and prepared Become.
7. The use of zinc (I) tartrate in stabilizers according to claim 6, characterized in that the weight ratio of said zinc stearate and zinc (I) tartrate is 0-1:1.

Images