Antioxidant for PVC, its preparation method and application

Abstract

The present application relates to fine chemical technology field, especially to IPC C08L27, more particularly to a PVC antioxidant and its preparation method and application. The PVC antioxidant in the present application comprises 15-30 parts of phosphite, 50-70 parts of mixed alcohol, 0.01-5 parts of catalyst. A novel PVC antioxidant is prepared in the present application, which has novel composition structure, and has better antioxidant property, high temperature resistance and color improvement. The preparation method in the present application is simple, the raw materials are non-toxic and harmless, and the application range is wide.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and more particularly to IPC C08L27, and more specifically to an antioxidant for PVC, its preparation method and application. Background Technology

[0002] Polyvinyl chloride (PVC) is a general-purpose resin, and its industrial production methods mainly include suspension polymerization, emulsion polymerization, micro-suspension polymerization, and bulk polymerization. Suspension polymerization is the most common, accounting for approximately 75%. When heated, PVC begins to soften at 65-85°C. Above 100°C, a dehydrochlorination reaction occurs. At PVC processing temperatures (around 170°C), the degradation rate accelerates, resulting not only in dehydrochlorination but also in discoloration and macromolecular cross-linking. Therefore, stabilizers and other additives must be added to PVC resin to obtain the various products required.

[0003] In PVC formulations, phosphites are generally considered to primarily act as chelating agents. When used alone, they have no significant stabilizing effect, but when used in combination with metal soaps, they can complex metal chlorides, improving heat resistance and weather resistance while maintaining transparency. They can also exhibit synergistic effects when used with organotin compounds and epoxy compounds. They can reduce the amount of primary stabilizers, especially expensive organotin stabilizers. Phosphites are widely used in liquid composite stabilizers, accounting for approximately 10% to 30% of the total. They have a wide application in PVC product formulations, particularly in transparent products, with a typical dosage of 0.3% to 1.0%.

[0004] Existing patent CN201410766897.9 discloses an amphiphilic compound containing hindered phenols and phosphites, its synthesis method, and its application. The application of this compound improves its compatibility, antioxidant properties, and antistatic effects in resins. However, it contains phenols and benzene, classifying it as a toxic product, thus limiting its application scope.

[0005] Existing patent CN201110134773.5 discloses a polyvinyl chloride stabilizer and its synthesis process, which can be used in polymers during high-temperature processing and has good lubrication and speed-up effects. However, it will cause a "zinc burning" phenomenon in the later stage, which causes the polyvinyl chloride to turn black rapidly. Summary of the Invention

[0006] To address the problems in the prior art, the first aspect of the present invention provides an antioxidant for PVC, the raw materials for which include phosphite, mixed alcohol, and catalyst.

[0007] Preferably, the antioxidant for PVC is prepared by means of 15-30 parts by weight of phosphite, 50-70 parts by weight of mixed alcohol, and 0.01-5 parts by weight of catalyst; more preferably, it comprises 20-25 parts by weight of phosphite, 57-60 parts by weight of mixed alcohol, and 1-3 parts by weight of catalyst.

[0008] In some preferred embodiments, the antioxidant for PVC is prepared from raw materials comprising, by weight, 20 parts phosphite, 60 parts mixed alcohol, and 2 parts catalyst.

[0009] Preferably, the weight ratio of the phosphite to the mixed alcohol is 1:(2-3); more preferably, it is 1:(2.2-3).

[0010] Preferably, the phosphite includes one or more of triethyl phosphite, trimethyl phosphite, and tripropyl phosphite; more preferably, it is triethyl phosphite.

[0011] Preferably, the mixed alcohols include one or more of octadecanol, dodecyl alcohol, and hexadecyl alcohol; more preferably, they are dodecyl alcohol or hexadecyl alcohol.

[0012] Preferably, the catalyst comprises one or more of ethanolamine, diethanolamine, triethanolamine, ethylenediamine, triethylamine, diisopropylamine, and tri-n-butylamine; more preferably, it is tri-n-propylamine or triethanolamine.

[0013] In this invention, mixed alcohols are used as reactants, particularly reacting with phosphites to prepare a novel antioxidant for PVC, exhibiting excellent high-temperature resistance and color-modifying properties. The inventors have discovered that a mixed antioxidant is obtained through a preparation process via the reaction of phosphites with mixed alcohols, comprising... When the raw material is dodecyltetradecyl alcohol, R1, R2, and R2 are C12 alkyl or C14 alkyl; when the raw material is hexadecyl alcohol, R1, R2, and R2 are C16 alkyl or C18 alkyl. This oxidant has a novel composition and structure and exhibits good antioxidant properties. Furthermore, the presence of phosphorus in the antioxidant helps maintain the color of PVC during use. Simultaneously, the combination of phosphorus with alkoxy groups increases its molecular weight, thereby enhancing its activity. The reaction of phosphites with dodecyltetradecyl alcohol and hexadecyl alcohol yields an antioxidant for PVC with a high boiling point, broadening its application range in PVC processing. It performs better at high temperatures, improving the weather resistance and high-temperature resistance of PVC materials.

[0014] In this invention, by adding a mixture of alcohols, dodecyltetradecyl alcohol or hexadecyl alcohol, as reactants, the product yield is improved, the reactant conversion rate is high, and the residue is low. The inventors discovered that, during research conducted under the concept of this invention, most reactions of alcohols with phosphites resulted in low product yields, low reactant conversion rates, and high residues, as seen in Comparative Examples 1 and 2, making the experiments impossible. The inventors then unexpectedly discovered that adding a mixture of alcohols, dodecyltetradecyl alcohol or hexadecyl alcohol, resulted in high product yields, high reactant conversion rates, and low residues.

[0015] In this invention, an antioxidant for PVC with strong antioxidant properties and excellent color-modifying properties is prepared by using 20-25 parts of phosphite, 57-60 parts of mixed alcohol, and 1-3 parts of catalyst. The inventors have creatively discovered that the antioxidant prepared by using 20-25 parts of phosphite, 57-60 parts of mixed alcohol, and 1-3 parts of catalyst, when applied to PVC production, exhibits almost no significant color change within 20-30 minutes, while PVC treated with other antioxidants shows obvious discoloration. Furthermore, the PVC antioxidant can also lighten the chromophores of hindered phenolic antioxidants after oxidation, thereby maintaining good color. Therefore, the addition of the antioxidant of this invention can improve the color-modifying properties of PVC.

[0016] A second aspect of this invention provides a method for preparing an antioxidant for PVC, comprising the following steps:

[0017] S1: Close the three-way stopcock of the constant pressure funnel in the four-necked reaction flask and add the phosphite into the constant pressure funnel;

[0018] S2: Add the catalyst and mixed alcohol to a four-necked reaction flask, heat to 130-160°C, collect the distillate while adding triethyl phosphite dropwise, observe the distillation, react for 6-8 hours, if no distillation occurs, the reaction is ended, cool to room temperature, filter to obtain the antioxidant for PVC.

[0019] Preferably, the temperature in step S2 is raised to 140–150°C.

[0020] In this invention, by employing specific steps to reflux triethyl phosphite, mixed alcohols, and a catalyst at high temperatures, the antioxidant properties and high-temperature resistance of the PVC antioxidant are improved. The inventors unexpectedly discovered that the antioxidant prepared in this invention can decompose macromolecular hydroperoxides, converting them into hydroxyl compounds, thereby stabilizing them and terminating the chain reaction. Simultaneously, this PVC antioxidant can inhibit and mitigate the formation of hydrogen peroxide after plasticizer oxidation, preventing further oxidation of the plasticizer and reducing PVC yellowing.

[0021] A third aspect of the present invention provides an application of an antioxidant for PVC, used in the preparation of polyvinyl chloride.

[0022] Beneficial effects

[0023] 1. In this invention, mixed alcohols, especially dodecyltetradecyl alcohol and hexadecyl alcohol, are used as reactants to react with phosphites to prepare a novel antioxidant for PVC, which has excellent high temperature resistance and color improvement properties.

[0024] 2. In this invention, by using specific steps to reflux triethyl phosphite, mixed alcohol, and catalyst at high temperature, the antioxidant properties and high-temperature resistance of the antioxidant for PVC are improved.

[0025] 3. In this invention, an antioxidant for PVC with strong antioxidant properties and excellent color-improving properties is prepared by using 20-25 parts of phosphite, 57-60 parts of mixed alcohol, and 1-3 parts of catalyst.

[0026] 4. In this invention, the preparation method is simple, and the raw materials used are non-toxic and harmless. The synthesized antioxidant for PVC is free of phenol and benzene, and belongs to the category of non-toxic and harmless antioxidants. At the same time, the synthesized antioxidant does not have the pungent odor of phosphite itself, and its application range is wider.

[0027] 5. The antioxidant for PVC prepared and synthesized in this invention has a good synergistic effect with the light stabilizer. At the same time, it can increase the processing temperature of polymers such as PVC and reduce the processing viscosity during molding. Attached Figure Description

[0028] Figure 1 This is a gas chromatogram of the antioxidant for PVC in Example 1; the main product elutes at 23 min and 30 min.

[0029] Figure 2 This is a gas chromatographic analysis report of the antioxidant used in PVC in Comparative Example 1;

[0030] Figure 3 This is a gas chromatographic analysis report of the antioxidant used in PVC in Comparative Example 2;

[0031] Figure 4 To add the antioxidants for PVC from Examples 1-3 respectively, 8 parts Dynamic comparison chart of PVC samples 2040, 8 ZY-61, and 10 ZY-61;

[0032] Figure 5 To add the antioxidants for PVC from Examples 1-3 respectively, 8 parts Static comparison images of PVC samples 2040, 8 ZY-61, and 10 ZY-61. Detailed Implementation

[0033] Example 1

[0034] The first aspect of this embodiment provides an antioxidant for PVC, the raw materials for which, by weight, are 20 parts triethyl phosphite, 60 parts dodecyltetradecyl alcohol, and 2 parts triethanolamine.

[0035] The second aspect of this embodiment provides a method for preparing an antioxidant for PVC, comprising the following steps:

[0036] S1: Close the three-way stopcock of the constant pressure funnel in the four-necked reaction flask, and add triethyl phosphite into the constant pressure funnel;

[0037] S2: Add triethanolamine and dodecyltetracodone to a four-necked reaction flask, heat to 145°C, and collect the distillate while adding triethyl phosphite dropwise. Observe the distillation process. React for 8 hours. If no distillate is collected, the reaction is terminated. Cool to 25°C, filter, and obtain the antioxidant for PVC. See the gas chromatographic analysis report for details. Figure 1 .

[0038] The CAS number of the triethyl phosphite is 122-52-1; the dodecyltetradecyl alcohol was purchased from Coning, Thailand, and is designated as 1214 alcohol; the CAS number of the triethanolamine is 102-71-6.

[0039] Example 2

[0040] The first aspect of this embodiment provides an antioxidant for PVC, the raw materials for which, by weight, are 20 parts triethyl phosphite, 60 parts cetearyl alcohol, and 2 parts triethanolamine.

[0041] The second aspect of this embodiment provides a method for preparing an antioxidant for PVC, comprising the following steps:

[0042] S1: Close the three-way stopcock of the constant pressure funnel in the four-necked reaction flask, and add triethyl phosphite into the constant pressure funnel;

[0043] S2: Add triethanolamine and cetearyl alcohol to a four-necked reaction flask, heat to 145°C, and collect the distillate while adding triethyl phosphite dropwise. Observe the distillation. React for 8 hours. If there is no distillation, the reaction is over. Cool down to 25°C and filter to obtain the antioxidant for PVC.

[0044] The CAS number of the triethyl phosphite is 122-52-1; the cetearyl alcohol was purchased from Coning, Thailand, and its model is 1618 alcohol; the CAS number of the triethanolamine is 102-71-6.

[0045] Example 3

[0046] The first aspect of this embodiment provides an antioxidant for PVC, the raw materials for which, by weight, are 20 parts triethyl phosphite, 60 parts dodecyltetradecyl alcohol, and 2 parts tri-n-propylamine.

[0047] The second aspect of this embodiment provides a method for preparing an antioxidant for PVC, comprising the following steps:

[0048] S1: Close the three-way stopcock of the constant pressure funnel in the four-necked reaction flask, and add triethyl phosphite into the constant pressure funnel;

[0049] S2: Add tri-n-propylamine and dodecyltetradecyl alcohol to a four-necked reaction flask, heat to 145°C, and collect the distillate while adding triethyl phosphite dropwise. Observe the distillation. React for 8 hours. If there is no distillation, the reaction is over. Cool down to 25°C and filter to obtain the antioxidant for PVC.

[0050] The CAS number of the triethyl phosphite is 122-52-1; the dodecyltetradecyl alcohol was purchased from Coning, Thailand, and is designated as 1214 alcohol; the CAS number of the tri-n-propylamine is 102-69-2.

[0051] Comparative Example 1

[0052] The specific implementation method of this comparative example is the same as that of Example 1, except that the raw materials used in the preparation, by weight, are 20 parts triethyl phosphite, 60 parts oleyl alcohol, and 2 parts triethanolamine. The gas chromatography analysis report of the PVC antioxidant prepared according to the above embodiment is available here. Figure 2 .

[0053] The oleyl alcohol was purchased from Croda Chemicals Co., Ltd.

[0054] Comparative Example 2

[0055] The specific implementation method of this comparative example is the same as that of Example 1, except that the raw materials used in the preparation, by weight, are 20 parts triethyl phosphite, 60 parts isododecyl alcohol, and 2 parts triethanolamine. The gas chromatography analysis report of the PVC antioxidant prepared in this embodiment is available here. Figure 3 .

[0056] The isododecyl alcohol was purchased from Koning, Thailand.

[0057] Performance testing

[0058] Dynamic detection and static detection:

[0059] The specific PVC formula is as follows: 29 parts PVC powder (purchased from Hanwha Corporation, South Korea), 3 parts AOX1076 (purchased from BASF), 35 parts hydrotalcite, 20 parts zinc stearate, 5 parts DBM (purchased from Bengbu Jiaxian Company), and 8 parts... 2040 (purchased from Guangzhou Zhiyi Company) or 8 parts of PVC antioxidant (prepared in Examples 1-3) or 8 parts of ZY-61 (ZY-61 is phenyl diisooctyl phosphite, purchased from Jiangsu Changhe Company) or 10 parts of ZY-61 (ZY-61 is phenyl diisooctyl phosphite, purchased from Jiangsu Changhe Company).

[0060] Preparation method of 2040 or Example 1 or Example 2 or Example 3 or 8 or 10 ZY-61 samples: After accurately weighing according to the formula, pour them into a high-speed mixer and mix evenly, then put them into beakers for later use.

[0061] 1. Dynamic detection:

[0062] The above samples were added separately to a two-roll mixer for sample preparation, with the two rolls temperature set at 185℃. After repeatedly pressing the samples with the two rolls to obtain uniform sheets, the sheets were cut every 5 minutes, and the color was recorded. The color change of the sample sheets was recorded until they turned yellow. Dynamic testing can determine the antioxidant's ability to inhibit PVC color change. The color of the PVC over a certain period indicates the degradation status; the darker the color, the worse the inhibition of PVC color change and the greater the degradation.

[0063] See results Figure 4 .from Figure 4 It can be seen that the PVC with added antioxidants from Example 1, Example 2, or Example 3 turns yellow more slowly than the PVC with added antioxidants. 2040, 8 parts ZY-61, 10 parts ZY-61 PVC.

[0064] 2. Static testing:

[0065] The above samples were added separately to a two-roll mixer for test sheet preparation, with the two-roll temperature set at 185℃. After repeatedly pressing the sheets with the two rolls to obtain uniform sheets, the sheets were cut to obtain PVC samples. Different PVC samples were placed on a fixed device and then placed in an oven at a constant temperature of 190℃. The color change of the samples was recorded every 10 minutes until they turned black. The oven aging test can determine the effectiveness of the antioxidant in stabilizing PVC, especially its ability to inhibit color changes. It is generally believed that when PVC is heated, its color undergoes a series of changes from light to dark: white – yellow – brown – tan – black. The color of the PVC after a certain period can indicate the degradation status; the darker the color, the greater the degradation.

[0066] See results Figure 5 . Figure 5 The results show that the PVC with added antioxidants from Examples 1-3 was lighter in color than the PVC with added antioxidants at 20 and 30 minutes, and there was no significant color change at 20 and 30 minutes.

Claims

1. An antioxidant for PVC, characterized in that, The raw materials for preparing antioxidants for PVC, by weight, are: 20-25 parts phosphite, 57-60 parts mixed alcohol, and 1-3 parts catalyst; The weight ratio of the phosphite to the mixed alcohol is 1:(2-3). The mixed alcohol is either dodecanoic acid or hexadecanoic acid; The catalyst is triethanolamine; The phosphite includes one or more of triethyl phosphite, trimethyl phosphite, and tripropyl phosphite; The method for preparing the antioxidant for PVC includes the following steps: S1: Close the three-way stopcock of the constant pressure funnel in the four-necked reaction flask and add the phosphite into the constant pressure funnel; S2: Add the catalyst and mixed alcohol to a four-necked reaction flask, heat to 130-160°C, collect the distillate while adding phosphite dropwise, observe the distillation, react for 6-8 hours, if no distillation occurs, the reaction is finished, cool to room temperature, filter to obtain antioxidant for PVC.

2. The antioxidant for PVC according to claim 1, characterized in that, The weight ratio of the phosphite to the mixed alcohol is 1:(2.2-3).

3. The antioxidant for PVC according to claim 1, characterized in that, The temperature in S2 is raised to 140-150°C.

4. The application of the antioxidant for PVC according to any one of claims 1 to 3, characterized in that, It is used in the preparation of polyvinyl chloride.

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