CN109880252B - Heat stabilizer for chlorine-containing polymer - Google Patents

Abstract

The invention discloses a heat stabilizer for chlorine-containing polymers, which takes trihydroxymethyl aminomethane as a complexing agent, the complexing agent reacts with zinc oxide and insoluble organic acid in an aqueous medium, wherein the molar ratio of the complexing agent to the zinc oxide is 1-2:1, and the heat stabilizer can be obtained by refluxing until the reaction is complete when the pH value of a reaction system is neutral; the coordination compound containing a plurality of hydroxyl groups is introduced at the same time, can replace propenyl chlorine generated in the processing of chlorine-containing polymers or generate addition reaction with generated ethylenic bonds, and plays the role of additives such as polyhydric alcohol and the like.

Description

Heat stabilizer for chlorine-containing polymer

Technical Field

The invention relates to the technical field of chlorine-containing polymeric materials, in particular to a heat stabilizer for chlorine-containing polymers.

Background

Chlorine-containing polymers, such as polyvinyl chloride (PVC), copolymers of vinyl chloride and vinyl acetate, and poly (1, 1-dichloroethylene), and the like, are commonly used in the manufacture of many articles such as pipes, window profiles, baffles, bottles, wall coverings, and packaging films. Many attempts have been made to improve the color retention of polymer resins, particularly during processing, such as during initial processing and during any subsequent reprocessing, by adding stabilizers to the chlorine-containing polymers. Most stabilizer compositions in use today contain metals such as tin, barium, cadmium and even lead. While these stabilizer compositions are effective in reducing discoloration during initial processing as well as any subsequent reprocessing, there is increasing interest in developing stabilizers that do not contain tin, barium, cadmium, and/or lead for environmental and other reasons.

In China, the development and popularization of calcium-zinc heat stabilizers are vigorously carried out. Combinations of zinc and calcium carboxylates have been used as stabilizers, however most use alone or in combination as chlorine-containing polymer stabilizers results in zinc salts that degrade rapidly or "zinc burn" after a short period of good color. In order to obtain acceptable stability performance from the zinc-calcium combination, many additives or co-stabilizers must be used, thereby increasing the cost of the stabilizer system.

Disclosure of Invention

In order to solve the technical problems, the invention provides a heat stabilizer for chlorine-containing polymers, which has good heat stability.

The technical scheme is as follows: a heat stabilizer for chlorine-containing polymers is characterized by being prepared in the following way: trihydroxymethyl aminomethane is used as a complexing agent, the complexing agent reacts with zinc oxide and insoluble organic acid in an aqueous medium, wherein the molar ratio of the complexing agent to the zinc oxide is 1-2:1, and the reaction system is refluxed to complete reaction when the pH value is neutral, so that the heat stabilizer for the chlorine-containing polymer is obtained. The reaction product obtained by adopting the technical scheme can be directly used as a stabilizer without purification by removing water through reduced pressure distillation or simply separating water, so the product is called as a compound, the distilled or separated water can be directly recycled, the whole reaction process is carried out under normal pressure, three wastes are not released in the reaction process, the obtained product is directly applied to the processing of the chlorine-containing polymer, and the zinc can be orderly and stably released, so that the generation of zinc burning is slowed down or even inhibited; the coordination compound containing a plurality of hydroxyl groups is introduced at the same time, can replace propenyl chlorine generated in the processing of chlorine-containing polymers or generate addition reaction with generated ethylenic bonds, and plays the role of additives such as polyhydric alcohol and the like.

The insoluble organic acid is a saturated organic carboxylic acid. The organic carboxylic acid can be a monoacid, a diacid, a triacid, etc., wherein the mole ratio of the monoacid to the zinc oxide is 2:1, the mole ratio of the diacid to the zinc oxide is 1:1, and the mole ratio of the triacid to the zinc oxide is 2:3, which are conventional ratios for the reaction of the organic acid and the zinc oxide and will not be described in detail herein.

The insoluble organic acid is lauric acid, palmitic acid or stearic acid.

And a catalyst with the mass of 0.1-2% of that of the zinc oxide can be added into the reaction system, and the catalyst is formed by respectively combining hydrogen peroxide, perchloric acid or sodium perchlorate and acetic acid. The proportion of hydrogen peroxide, perchloric acid or sodium perchlorate to acetic acid in the catalyst can be any proportion.

And a phase transfer agent can be added into the reaction system, wherein the dosage of the phase transfer agent is 5-10% of the mass of the aqueous medium. The phase transfer agent can be ethanol, etc., and can be added in any ratio of 5-10%, such as 6%, 7%, 8%, 9%, etc.

The reaction system is stirred at 70-80 ℃ until the pH value is neutral, and the reflux is carried out at 100-105 ℃.

Has the advantages that: the whole reaction process is carried out at normal pressure and low temperature, no three wastes are released in the reaction process, the obtained product is directly applied to the processing of chlorine-containing polymers, the heat stabilizer is taken, the zinc can be orderly and stably released, and the zinc burning is slowed down or even inhibited; the coordination compound containing a plurality of hydroxyl groups is introduced at the same time, can replace propenyl chlorine generated in the processing of chlorine-containing polymers or generate addition reaction with generated ethylenic bonds, and plays the role of additives such as polyhydric alcohol and the like.

Detailed Description

Preparation of heat stabilizer

The raw materials adopted by the invention are as follows:

trihydroxymethyl aminomethane (THAM) as complexing agent is commercially available, and the conventional commercial grade is suitable for the implementation of the invention. It can also be prepared conventionally by condensation of nitroalkanes with aldehydes, followed by a reduction treatment. The complexing agent used in the invention has good solubility in water and ethanol. Trihydroxymethylaminomethane powder has a solubility of 500g/L in water and 22g/L in 95% ethanol at 25 ℃. The complexing agent used in the invention is alkaline when dissolved in water and ethanol, 0.1mol of trihydroxymethyl aminomethane water solution has a pH value of 10.4. The good solubility is beneficial to the reaction and the alkali reaction control and end point judgment after the dissolution.

The insoluble organic acid is lauric acid, stearic acid, industrial grade, and is commercially available, but the insoluble organic acid used in the invention can also be other acids such as palmitic acid, and the like, as long as the insoluble organic acid meets the condition that the insoluble organic acid is insoluble in cold or hot water and has a boiling point and a decomposition temperature higher than the processing temperature of the chlorine-containing polymer, and the temperature is generally not more than 250 ℃; the zinc oxide is rubber plastic grade and is commercially available.

The present invention will be further illustrated by the following specific examples and experimental data, wherein tris (hydroxymethyl) aminomethane is provided by Suzhou subfamily science and technology, Inc. and Shandong Enlang chemical, Inc.; the rest raw materials are purchased from the market and are of industrial grade. The mass g of the reaction participation material is 100 percent.

Example 1, preparation of zinc laurate (THAM) complexes:

40.06g (0.2mol) of lauric acid and 12.0g (0.1mol) of THAM are stirred in 200ml of distilled water to form an emulsion for later use.

In a 500 mL-four neck round bottom flask equipped with a condenser, 8.14g (0.1mol) of zinc oxide was suspended in 100mL of water with stirring, and a catalyst of 0.5% by mass of zinc oxide, which catalyst was composed of hydrogen peroxide and acetic acid, was added; heating to 75 ℃, adding the prepared emulsion, keeping the temperature at 72 +/-2 ℃ in the adding process, and finishing adding for about 0.5-1 hr; after the addition is finished, keeping the temperature at 70-80 ℃ for several hours until the pH value of the reaction system is equal to 7. Heating to 100-105 ℃, refluxing and preserving heat until the mass fraction of lauric acid is less than 1% (the mass fraction of the residual quantity of insoluble organic acid in the reaction system is less than 1%, namely the reaction end point), and vacuumizing to remove water to obtain a white solid zinc laurate (THAM) compound.

Example 2 lauric acid (THAM)₂Preparation of zinc complex:

operating as in example 1, but replacing 0.1mol of THAM by 0.2mol of THAM and replacing the catalyst consisting of sodium perchlorate and acetic acid (0.3% by mass of zinc oxide) by the catalyst consisting of hydrogen peroxide and acetic acid (0.5% by mass of zinc oxide), a white solid of lauric acid (THAM) was obtained₂A zinc complex.

Example 3, preparation of zinc stearate (THAM) complex:

56.9g (0.2mol) of stearic acid and 12.0g (0.1mol) of THAM are stirred in 350ml of distilled water and 25ml of ethanol to form an emulsion for later use.

In a 1000 mL-four neck round bottom flask equipped with a condenser, 8.14g (0.1mol) of zinc oxide was suspended in 150mL of water with stirring, and a catalyst of 1.0% by mass of zinc oxide, which was composed of hydrogen peroxide and acetic acid, was added; heating to 78 deg.C, adding the above emulsion, and maintaining the temperature at 78 + -2 deg.C for about 2 hr; after the addition was complete, the reaction was held for several hours until the pH was equal to 7. Heating to 100-105 ℃, refluxing and preserving heat until the mass fraction of stearic acid is less than 1%, and vacuumizing the alcohol-water solution for recycling to obtain a white solid zinc stearate (THAM) compound.

Example 4 stearic acid (THAM)₂Preparation of zinc complex:

operating as in example 3, but replacing 0.1mol of THAM by 0.2mol of THAM, stirring stearic acid and THAM into an emulsion in 500ml of distilled water +50ml of ethanol with stirring, replacing the catalyst consisting of hydrogen peroxide and acetic acid (1% by mass of zinc oxide) by a catalyst consisting of perchloric acid and acetic acid (2% by mass of zinc oxide), a white solid zinc stearate (THAM) complex was obtained.

Second, thermal stability experiment and anti-zinc burning experiment

(1) The thermal stability test uses the following test materials and equipment:

a rheometer: model XSS-300 Torque rheometer, manufactured by Shanghai scientific rubber and plastic machinery, Inc.; parameters are as follows: torque 35rpm, temperature 180 ℃ and time 7.5 min.

Testing equipment: model NS800 colorimeter, manufactured by 3NH technologies ltd.

The formula of the base material is shown in table 1, the heat stabilizer prepared in the embodiment of the invention is added into the base material to prepare a mixture for testing, THAM, zinc monthly silicate or zinc stearate is respectively added into the base material to be used as a heat stabilizer to prepare a mixture for comparison, and the formula of the mixture is shown in table 2:

TABLE 1 base material formulation

Name of material	Quantity (weight meter)
		PVC-SG5(K value)	100 portions of
CaCO3	20 portions of
		Rutile titanium dioxide	1.5 parts of
CPE 135	4.5 parts of

TABLE 2 blend formula

Name of material	Weight (g)
		Base material	68.5
Lubricant (OPE wax)	1
		Heat stabilizer	0.5
Total of	70

The testing steps are as follows: and uniformly mixing the materials according to the formula of the mixture, adding the mixture when a rheometer is stabilized at 180 ℃ and the torque is 35rpm, performing rheological operation for 7.5min, taking out a sample, and flattening to obtain a sample sheet to be tested.

The test judgment method comprises the following steps: the sample pieces were tested three times with a color tester to obtain the average b value for each sample piece. The larger the value of b, the worse the thermal stability; the smaller the b value, the better the thermal stability, and the test results are shown in table 3:

TABLE 3 thermal stability test results

Serial number	Heat stabilizer added into sample piece	Corresponding to the b value of the sample piece
			1	THAM	18.21
2	Zinc laurate	13.24
			3	Zinc laurate (THAM) complexes	11.70
4	Lauric acid (THAM)2Zinc complexes	14.67
			5	Zinc stearate	11.47
6	Zinc stearate (THAM) complexes	9.56
			7	Stearic acid (THAM)2Zinc complexes	13.31

From the test results, when the molar ratio of THAM to zinc oxide is 1:1, the thermal stability of the product is increased and is better than that of the corresponding zinc salt; when the molar ratio of THAM to zinc oxide is 2:1, the thermal stability of the product is reduced, all worse than the corresponding zinc salt, which may also be caused by the same mass of stabilizer versus the reduced zinc content.

(2) The experiment for preventing the zinc from burning comprises the following experimental materials and equipment:

a rheometer: model XSS-300 Torque rheometer, manufactured by Shanghai scientific rubber and plastic machinery, Inc.; parameters are as follows: torque 35rpm, temperature 180 ℃ and time 8 min.

Testing equipment: model NS800 colorimeter, manufactured by 3NH technologies ltd.

The formula of the base material is shown in table 4, the acid (THAM) zinc compound prepared in the embodiment of the invention is added into the base material to be used as a stabilizer to prepare a mixture for testing, in addition, the base material is added with industrial zinc acid salt (zinc monthly silicate or zinc stearate) to be used as a stabilizer to prepare a mixture for comparison, and the formula of the mixture is shown in table 5:

TABLE 4 base material formulation

Name of material	Quantity (weight meter)
		PVC-SG5(K value)	100 portions of
CaCO3	20 portions of
		Rutile titanium dioxide	1.5 parts of
CPE 135	4.5 parts of

TABLE 5 blend formula

The testing steps are as follows: and uniformly mixing the materials according to the formula of the mixture, adding the mixture when a rheometer is stabilized at 180 ℃ and the torque is 35rpm, performing rheological operation for 8min, taking out a sample, and flattening to obtain a sample sheet to be tested.

The test judgment method comprises the following steps: the sample pieces were tested three times with a color tester to obtain the average L value for each sample piece. The larger the L value is, the better the zinc burning resistance is; the smaller the L value, the poorer the zinc burn resistance, and the test results are shown in Table 6 below:

TABLE 6 anti-Zinc burn test results

Serial number	Stabilizers added to the sample pieces	Corresponding to L value of sample piece
			1	Zinc laurate (0.5g)	82.52
2	Zinc laurate (THAM) (0.5g)	86.67
			3	Lauric acid (THAM)2Zinc complex (0.5g)	90.85
4	Zinc stearate (0.5g)	86.28
			5	Stearic acid (THAM) zinc complex (0.5g)	91.55
6	Stearic acid (THAM)2Zinc complex (0.5g)	95.67

From the test results, acid (THAM) zinc complex and acid (THAM)₂The zinc compound has certain zinc burning resistance, and the zinc burning resistance is enhanced along with the increase of the proportion of the complexing agent THAM in the reactant.

From the above thermal stabilityAnd the Zinc burn resistance test shows that the thermal stability sequence is acid (THAM)₂Zinc complexes<Zinc salt of acid<The zinc acid (THAM) complex, the product being a zinc salt<Acid (THAM) zinc complexes<Acid (THAM)₂A zinc complex. Therefore, the complex compound product with the same thermal stability as the zinc salt can be synthesized by adjusting the proportion of THAM in the reaction raw materials, and meanwhile, the product also has zinc burning resistance which cannot be achieved by common zinc salt; or by mixing the product acid (THAM) zinc complex, acid (THAM)₂The zinc compound is mixed in a proper proportion to obtain a mixed composition with the same thermal stability as the zinc salt, and has zinc burning resistance which is difficult to achieve by common zinc salts.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.

Claims (2)

1. A heat stabilizer for chlorine-containing polymers, characterized by being prepared in the following manner: taking tris (hydroxymethyl) aminomethane as a complexing agent, reacting the complexing agent with zinc oxide and insoluble organic acid in an aqueous medium, wherein the molar ratio of the complexing agent to the zinc oxide is 1-2:1, and refluxing until the reaction is complete when the pH value of a reaction system is neutral to obtain the heat stabilizer for the chlorine-containing polymer; the insoluble organic acid is a saturated organic carboxylic acid;

a catalyst with the mass of 0.1-2% of that of zinc oxide is added into the reaction system, and the catalyst is formed by combining hydrogen peroxide, perchloric acid or sodium perchlorate and acetic acid respectively;

a phase transfer agent is added into the reaction system, and the dosage of the phase transfer agent is 5-10% of the mass of the aqueous medium;

the reaction system is stirred at 70-80 ℃ until the pH value is neutral, and the reflux is carried out at 100-105 ℃.

2. Heat stabilizer for chlorine-containing polymers according to claim 1, characterized in that: the insoluble organic acid is lauric acid, palmitic acid or stearic acid.