Composite heat stabilizer for PVC (polyvinyl chloride) and preparation method of composite heat stabilizer

Abstract

The invention provides a composite heat stabilizer for PVC (polyvinyl chloride) and a preparation method thereof, and the composite heat stabilizer for PVC comprises the following raw materials in parts by weight: 30-50 parts of zinc stearate; 40 to 60 parts of calcium stearate; 1-5 parts of a ketone compound; the ketone compound has a structure as shown in a formula (I). The composite heat stabilizer for PVC is good in heat stabilizing effect and long-term heat stability, and can effectively restrain the problems of zinc burning and the like.

Description

Technical Field

[0001] The invention relates to the field of polyvinyl chloride processing, in particular to a composite heat stabilizer for PVC and a preparation method thereof. Background Art

[0002] Polyvinyl chloride (PVC) is the second most common resin after polyethylene. It is widely used in films, pipes and other fields due to its low price and excellent performance. However, PVC molecular chains will release HCl when the temperature is above 110°C, and the released HCl will accelerate the thermal degradation of PVC, causing the color of PVC products to darken and the mechanical properties to deteriorate. Therefore, thermal stabilizers need to be added during the processing of PVC products to prevent thermal degradation.

[0003] At present, metal soap heat stabilizers, especially calcium zinc heat stabilizers, have become the mainstream products among PVC heat stabilizers due to their advantages such as non-toxicity, environmental protection and moderate price. However, zinc salts have a strong ability to inhibit the discoloration of PVC, so the color of the initial products is good. However, in the later stage, the generated ZnCl2 has a strong catalytic effect of removing HCl, which makes its long-term burning resistance worse. In the later stage, it is easy to change color violently, resulting in zinc burning, making the PVC products have black spots or turn completely black. Therefore, the long-term thermal stability is poor. Summary of the invention

[0004] The object of the present invention is to provide a composite heat stabilizer for PVC to solve the problem of poor long-term thermal stability of the composite heat stabilizer for PVC in the prior art.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A composite heat stabilizer for PVC, comprising the following raw materials in parts by weight:

[0007] 30-50 parts of zinc stearate; 40-60 parts of calcium stearate; 1-5 parts of ketone compound;

[0008] Wherein, the ketone compound has a structure as shown in formula (I):

[0009]

[0010]

[0011] The CAS number of the ketone compound is 105685-96-9.

[0012] Preferably, the composite heat stabilizer for PVC further comprises an auxiliary metal salt; the amount of the auxiliary metal salt is 10-15 parts.

[0013] Preferably, the auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide, and then reacting with calcium chloride and zinc chloride;

[0014]

[0015] The CAS number of the organic acid is 128043-82-3.

[0016] The present invention also provides a method for preparing the composite heat stabilizer for PVC, comprising the following steps: taking zinc stearate, calcium stearate and ketone compounds and mixing them uniformly to obtain the composite heat stabilizer.

[0017] Preferably, the method for preparing the composite heat stabilizer for PVC further comprises the step of adding an auxiliary metal salt thereto, wherein the auxiliary metal salt is obtained by the following method:

[0018] (1) taking a sodium hydroxide solution, adding an organic acid having a structure as shown in formula (II) thereto, stirring and reacting at 25-45° C. for 1-3 hours to obtain a solution containing sodium organic acid;

[0019]

[0020] (2) Add calcium chloride and zinc chloride to the solution containing sodium organic acid obtained in step (1), and react at 25-45° C. for 2-5 hours to obtain an auxiliary metal salt.

[0021] Preferably, in step (1), the concentration of the sodium hydroxide solution is 8-10 mol / L.

[0022] Preferably, in step (1), the volume ratio of the organic acid to the sodium hydroxide solution is 1:(10-20).

[0023] Preferably, the weight ratio of the organic acid, the calcium chloride and the zinc chloride is 1:(1-3):(0.5-1.0).

[0024] Preferably, step (2) specifically comprises the following steps: firstly, adding zinc chloride to the solution containing sodium organic acid obtained in step (1), stirring and reacting for 1-2 hours; then adjusting the pH value of the reaction solution to 7-8, adding calcium chloride thereto, and stirring and reacting for 1-2 hours.

[0025] Preferably, step (2) further comprises the steps of filtering, washing and drying the obtained auxiliary metal salt.

[0026] The above solution of the present invention includes at least the following beneficial effects:

[0027] (1) The composite heat stabilizer for PVC of the present invention comprises the following raw materials in parts by weight: 30-50 parts of zinc stearate; 40-60 parts of calcium stearate; 1-5 parts of ketone compound; the ketone compound has a structure as shown in formula (I). The composite heat stabilizer for PVC has good heat stabilization effect and good long-term heat stability, and can effectively solve the problems of "zinc burning".

[0028] Among them, the zinc element of the zinc stearate has electronegativity and strong electron-withdrawing ability, and can form a coordination bond with the unstable chloride ions in the PVC molecular chain, thereby preventing the PVC from escaping HCl, while the calcium element in the calcium stearate has a small electronegativity and weak electron-withdrawing ability, but can form a synergistic effect with the zinc stearate, extending the long-term thermal stability of the composite thermal stabilizer for the PVC. And the ketone compound, on the one hand, the imidazole group and carbon-alkoxy group it has can react with the unstable chlorine atoms on the PVC main chain to undergo nucleophilic substitution reaction, replacing the unstable chlorine atoms. In addition, the nitrogen atom on the imidazole group has a strong proton binding ability under acidic conditions, which can neutralize the HCl escaping from the PVC molecular chain and inhibit its catalytic effect on the thermal degradation of PVC. On the other hand, the long-chain structure it has has good compatibility with the PVC main chain, and it is not easy to form two phases after mixing with the PVC resin in a molten state, so that the PVC product has a higher transparency, which also helps to exert thermal stability.

[0029] (2) The composite heat stabilizer for PVC of the present invention, the auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide, and then reacting with calcium chloride and zinc chloride. The auxiliary metal salt has a similar structure to the ketone compound, and the two have good compatibility. More importantly, the auxiliary metal salt can undergo a replacement reaction with HCl released from the PVC molecular chain, and has a cyclic triketone structure. The conjugated system formed by the auxiliary metal salt can capture free radicals in the degradation process through electron delocalization, interrupt the free radical chain reaction, and effectively complex the zinc ions in ZnCl2 generated by the replacement reaction, thereby reducing the catalytic activity of zinc ions, inhibiting the "zinc burning" phenomenon, and improving the long-term thermal stability of the heat stabilizer. DETAILED DESCRIPTION

[0030] In the embodiments of the present invention, if the specific conditions are not specified, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. Raw materials of different manufacturers and models do not affect the implementation of the technical solution of the present invention and the realization of the technical effects.

[0031] In the following examples, the ketone compound has a structure as shown in formula (I):

[0032]

[0033] The organic acid has a structure as shown in formula (II):

[0034]

[0035] Example 1

[0036] The composite heat stabilizer for PVC in this embodiment includes the following raw materials in parts by weight:

[0037] 30 parts of zinc stearate; 50 parts of calcium stearate; 1 part of ketone compound; 12 parts of auxiliary metal salt;

[0038] The auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide, and then reacting with calcium chloride and zinc chloride.

[0039] The preparation method of the composite heat stabilizer for PVC described in this embodiment comprises the following steps: zinc stearate, calcium stearate, ketone compound and auxiliary metal salt are mixed evenly to obtain the composite heat stabilizer.

[0040] Wherein, the auxiliary metal salt is obtained by the following method:

[0041] (1) taking a sodium hydroxide solution, adding an organic acid having a structure as shown in formula (II) thereto, stirring and reacting at 25° C. for 3 hours to obtain a solution containing sodium organic acid;

[0042] Wherein, the concentration of the sodium hydroxide solution is 10 mol / L; the volume ratio of the organic acid to the sodium hydroxide solution is 1:20.

[0043] (2) First, zinc chloride is added to the solution containing sodium organic acid obtained in step (1), and the mixture is stirred for reaction for 1 hour; then the pH value of the reaction solution is adjusted to 7.5, calcium chloride is added thereto, and the mixture is stirred for reaction for 2 hours; the obtained auxiliary metal salt is filtered, washed, and dried.

[0044] Wherein, the weight ratio of the organic acid, the calcium chloride and the zinc chloride is 1:2:0.5.

[0045] Example 2

[0046] The composite heat stabilizer for PVC in this embodiment includes the following raw materials in parts by weight:

[0047] 50 parts of zinc stearate; 60 parts of calcium stearate; 3 parts of ketone compound; 15 parts of auxiliary metal salt;

[0048] The auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide, and then reacting with calcium chloride and zinc chloride.

[0049] The preparation method of the composite heat stabilizer for PVC described in this embodiment comprises the following steps: zinc stearate, calcium stearate, ketone compound and auxiliary metal salt are mixed evenly to obtain the composite heat stabilizer.

[0050] Wherein, the auxiliary metal salt is obtained by the following method:

[0051] (1) taking a sodium hydroxide solution, adding an organic acid having a structure as shown in formula (II) thereto, stirring and reacting at 45° C. for 2 h to obtain a solution containing sodium organic acid;

[0052] Wherein, the concentration of the sodium hydroxide solution is 8 mol / L; and the volume ratio of the organic acid to the sodium hydroxide solution is 1:15.

[0053] (2) First, zinc chloride is added to the solution containing sodium organic acid obtained in step (1), and the mixture is stirred for reaction for 2 h; then the pH value of the reaction solution is adjusted to 8, calcium chloride is added thereto, and the mixture is stirred for reaction for 1 h; the obtained auxiliary metal salt is filtered, washed, and dried.

[0054] Wherein, the weight ratio of the organic acid, the calcium chloride and the zinc chloride is 1:3:1.0.

[0055] Example 3

[0056] The composite heat stabilizer for PVC in this embodiment includes the following raw materials in parts by weight:

[0057] 40 parts of zinc stearate; 40 parts of calcium stearate; 5 parts of ketone compound; 10 parts of auxiliary metal salt;

[0058] The auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide, and then reacting with calcium chloride and zinc chloride.

[0059] The preparation method of the composite heat stabilizer for PVC described in this embodiment comprises the following steps: zinc stearate, calcium stearate, ketone compound and auxiliary metal salt are mixed evenly to obtain the composite heat stabilizer.

[0060] Wherein, the auxiliary metal salt is obtained by the following method:

[0061] (1) taking a sodium hydroxide solution, adding an organic acid having a structure as shown in formula (II) thereto, stirring and reacting at 35° C. for 1 hour to obtain a solution containing sodium organic acid;

[0062] Wherein, the concentration of the sodium hydroxide solution is 9 mol / L; and the volume ratio of the organic acid to the sodium hydroxide solution is 1:10.

[0063] (2) First, zinc chloride is added to the solution containing sodium organic acid obtained in step (1), and the mixture is stirred for reaction for 2 h; then the pH value of the reaction solution is adjusted to 7, calcium chloride is added thereto, and the mixture is stirred for reaction for 2 h, and the obtained auxiliary metal salt is filtered, washed, and dried.

[0064] Wherein, the weight ratio of the organic acid, the calcium chloride and the zinc chloride is 1:1:0.8.

[0065] Example 4

[0066] The composite heat stabilizer for PVC in this embodiment includes the following raw materials in parts by weight:

[0067] 35 parts of zinc stearate; 55 parts of calcium stearate; 5 parts of ketone compound; 15 parts of auxiliary metal salt;

[0068] The auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide, and then reacting with calcium chloride and zinc chloride.

[0069] The preparation method of the composite heat stabilizer for PVC described in this embodiment comprises the following steps: zinc stearate, calcium stearate, ketone compound and auxiliary metal salt are mixed evenly to obtain the composite heat stabilizer.

[0070] Wherein, the auxiliary metal salt is obtained by the following method:

[0071] (1) taking a sodium hydroxide solution, adding an organic acid having a structure as shown in formula (II) thereto, stirring and reacting at 30° C. for 3 h to obtain a solution containing sodium organic acid;

[0072] Wherein, the concentration of the sodium hydroxide solution is 10 mol / L; the volume ratio of the organic acid to the sodium hydroxide solution is 1:20.

[0073] (2) First, zinc chloride is added to the solution containing sodium organic acid obtained in step (1), and the mixture is stirred for reaction for 2 h; then the pH value of the reaction solution is adjusted to 7, calcium chloride is added thereto, and the mixture is stirred for reaction for 2 h, and the obtained auxiliary metal salt is filtered, washed, and dried.

[0074] Wherein, the weight ratio of the organic acid, the calcium chloride and the zinc chloride is 1:2:0.6.

[0075] Comparative Example 1

[0076] The raw materials and preparation method of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the auxiliary metal salt is not included.

[0077] Comparative Example 2

[0078] The raw materials and preparation method of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the ketone compound is not included.

[0079] Comparative Example 3

[0080] The raw materials of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the preparation method of the auxiliary metal salt is different. The auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide and then with calcium chloride.

[0081] Step (2) of this comparative example is specifically as follows: adjusting the pH value of the solution containing sodium organic acid obtained in step (1) to 7, adding calcium chloride thereto, stirring the reaction for 2 hours, filtering, washing and drying the obtained auxiliary metal salt.

[0082] Comparative Example 4

[0083] The raw materials of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the preparation method of the auxiliary metal salt is different. The auxiliary metal salt is replaced by a product obtained by reacting stearic acid with sodium hydroxide and then with zinc chloride and calcium chloride.

[0084] The auxiliary metal salt of this comparative example is obtained by the following method:

[0085] (1) taking a sodium hydroxide solution, adding stearic acid thereto, stirring and reacting at 30° C. for 3 h to obtain a solution containing organic acid sodium;

[0086] Wherein, the concentration of the sodium hydroxide solution is 10 mol / L; the volume ratio of the stearic acid to the sodium hydroxide solution is 1:20.

[0087] (2) First, zinc chloride is added to the solution containing sodium organic acid obtained in step (1), and the mixture is stirred for reaction for 2 h; then the pH value of the reaction solution is adjusted to 7, calcium chloride is added thereto, and the mixture is stirred for reaction for 2 h, and the obtained auxiliary metal salt is filtered, washed, and dried.

[0088] Wherein, the weight ratio of the stearic acid, the calcium chloride and the zinc chloride is 1:2:0.6.

[0089] Comparative Example 5

[0090] The raw materials and preparation method of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the ketone compound is replaced by 1-butylimidazolidine-2,4,5-trione.

[0091] The CAS number of 1-butylimidazolidine-2,4,5-trione is 40408-40-0, and it has the structure shown in formula (III):

[0092]

[0094]

[0095] Comparative Example 6

[0096] The raw materials and preparation method of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the weight portion of the auxiliary metal salt is 20 parts.

[0097] Comparative Example 7

[0098] The raw materials and preparation method of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the weight portion of the ketone compound is 10 parts.

[0099] Comparative Example 8

[0100] The raw materials and preparation method of the composite heat stabilizer for PVC in this comparative example are the same as those in Example 4, and the only difference is that the ketone compound and the auxiliary metal salt are not included.

[0101] Effect experiment example

[0102] In order to verify the technical effect of the preparation method of the composite heat stabilizer for PVC of the present invention, the following test was carried out:

[0103] The composite heat stabilizer for PVC was prepared by the method in Examples 1-4 and Comparative Examples 1-8, and test samples were prepared according to the following raw materials in parts by weight:

[0104] 100 parts of PVC, 1.2 parts of the composite heat stabilizer for PVC, 1.0 parts of ACR, and 0.5 parts of oxidized polyethylene wax.

[0105] The above raw materials were mixed evenly, placed on a double-roll plasticizer with a roller temperature of 170°C and a roller distance of 1mm for plasticization for 5 minutes to obtain a sheet, which was cut into a size of 2cm×2cm as a test sample. According to the requirements of GB / T7141-92 standard, the test sample was placed in an aging oven and an aging test was carried out at 190±1°C. The test sample was taken out every 30 minutes to observe and record the change of the yellowness value (Y) of ASTME313 standard.

[0106] After experimentation, the results are as follows:

[0107]

[0108]

[0109] According to the results of Examples 1-4 and Comparative Examples 1-8, the composite heat stabilizer for PVC of the present invention has good heat stabilization effect and good long-term heat stability, and can significantly inhibit the "zinc burning" phenomenon.

[0110] According to the results of Example 4 and Comparative Examples 1, 3, and 4, the addition of the auxiliary metal salt can significantly improve the thermal stability of the composite heat stabilizer for PVC and delay the occurrence of the "zinc burning" phenomenon. The product obtained by reacting a specific organic acid with a ring structure with sodium hydroxide and then with calcium chloride can improve the thermal stability of the composite heat stabilizer for PVC to a certain extent, but the thermal stability is poorer than that of the auxiliary metal salt in Example 4. The product prepared by the same method using long-chain stearic acid has little effect on improving the thermal stability of the composite heat stabilizer for PVC.

[0111] According to the results of Example 4 and Comparative Examples 2 and 5, the addition of the ketone compound can significantly improve the thermal stabilization effect of the composite heat stabilizer for PVC. However, the ketone compound with a specific cyclic structure combined with a short chain has poor compatibility with the PVC system. Although it can improve the thermal stability to a certain extent, the yellowness value at 0min is high, the initial colorability is poor, and the long-term thermal stability is not ideal.

[0112] According to the results of Example 4 and Comparative Examples 6 and 7, excessive amounts of the auxiliary metal salt and the ketone compound will have an adverse effect on the thermal stability effect. In particular, when the ketone compound is excessive, the long-term thermal stability effect is greatly affected.

[0113] According to the results of Example 4 and Comparative Examples 1, 2, and 8, the auxiliary metal salt and the ketone compound have a synergistic effect on improving the long-term thermal stability of PVC.

[0114] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A composite heat stabilizer for PVC, characterized in that: The invention comprises the following raw materials in parts by weight: 30-50 parts of zinc stearate; 40-60 parts of calcium stearate; 1-5 parts of ketone compound; Wherein, the ketone compound has a structure as shown in formula (I):

2. The composite heat stabilizer for PVC according to claim 1, characterized in that It also includes auxiliary metal salt; the amount of the auxiliary metal salt is 10-15 parts.

3. The composite heat stabilizer for PVC according to claim 2, characterized in that: The auxiliary metal salt is obtained by reacting an organic acid having a structure as shown in formula (II) with sodium hydroxide, and then reacting with calcium chloride and zinc chloride; 4. A method for preparing a composite heat stabilizer for PVC according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: zinc stearate, calcium stearate and ketone compounds are mixed evenly to obtain the product.

5. The method for preparing a composite heat stabilizer for PVC according to claim 4, characterized in that: The invention also includes the step of adding an auxiliary metal salt thereto, wherein the auxiliary metal salt is obtained by the following method: (1) taking a sodium hydroxide solution, adding an organic acid having a structure as shown in formula (II) thereto, stirring and reacting at 25-45° C. for 1-3 hours to obtain a solution containing sodium organic acid; (2) Add calcium chloride and zinc chloride to the solution containing sodium organic acid obtained in step (1), and react at 25-45° C. for 2-5 hours to obtain an auxiliary metal salt.

6. The method for preparing a composite heat stabilizer for PVC according to claim 5, characterized in that: In step (1), the concentration of the sodium hydroxide solution is 8-10 mol / L.

7. The method for preparing a composite heat stabilizer for PVC according to claim 5, characterized in that: In step (1), the volume ratio of the organic acid to the sodium hydroxide solution is 1:(10-20).

8. The method for preparing a composite heat stabilizer for PVC according to claim 5, characterized in that: The weight ratio of the organic acid, the calcium chloride and the zinc chloride is 1:(1-3):(0.5-1.0).

9. The method for preparing a composite heat stabilizer for PVC according to claim 5, characterized in that: Step (2) specifically comprises the following steps: firstly, zinc chloride is added to the solution containing sodium organic acid obtained in step (1), and the mixture is stirred for reaction for 1-2 hours; then, the pH value of the reaction solution is adjusted to 7-8, calcium chloride is added thereto, and the mixture is stirred for reaction for 1-2 hours.

10. The method for preparing a composite heat stabilizer for PVC according to claim 5, characterized in that: Step (2) also includes filtering, washing and drying the obtained auxiliary metal salt.

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