A heat stabilizer and preparation method thereof

Abstract

The present invention belongs to the field of fine chemical technology, and in particular relates to a heat stabilizer and a preparation method thereof. The heat stabilizer comprises the following components, measured in parts by weight: 20 to 40 parts of zinc stearate, 36 to 50 parts of an auxiliary stabilizer, 2 to 5 parts of a PVC crosslinker, and 1 to 3 parts of a crosslinking aid. The present invention designs and synthesizes an auxiliary stabilizer, which, when combined with zinc stearate, can significantly improve the long-term stability of PVC products and ensure their excellent thermal stability. The auxiliary stabilizer of the present invention has a synergistic effect with zinc stearate, which originates from the reaction between the auxiliary stabilizer and ZnCl2 (derived from the product of the reaction between zinc stearate and PVC). The auxiliary stabilizer can act as a chelating agent for metal chlorides, and delays the "zinc burn" phenomenon of PVC by forming an inert complex.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat stabilizers, and in particular relates to a heat stabilizer and a preparation method thereof. Background Art

[0002] Thermal stabilizers are the most important additives for polyvinyl chloride (PVC). Their core function is to inhibit thermal degradation reactions caused by inherent structural defects in the polymer chain during thermal processing. The mechanism of action of thermal stabilizers is generally believed to be to absorb hydrogen chloride released during PVC degradation or to react with unstable chlorine atoms such as allyl chloride and tertiary chlorine atoms, thereby enhancing thermal stability. Currently, the main commercial stabilizers used in PVC include lead salts, organotin compounds, metal soaps, and organic stabilizers.

[0003] CN109929191A discloses a high-efficiency heat stabilizer composed of the following components by weight: 0.15-0.23 parts of a polymerization inhibitor, 20-45 parts of an auxiliary heat stabilizer, 15-20 parts of zinc oxide, 2-6 parts of β-diketone, 10-25 parts of castor oil, 1-4 parts of 3-dimethyl-6-aminouracil, 200-500 parts of a lubricant, 5-8 parts of zinc stearate, 4-7 parts of a phosphite, 5-16 parts of tribasic lead sulfate, 1-3 parts of a monoglyceride, and 0.6-1.2 parts of a hyperdispersant. This patent discloses a heat stabilizer composition for latex-processed chlorinated natural rubber, comprising a hindered phenol, a stearate, an organotin compound, and an epoxidized vegetable oil. This patent significantly improves the thermal stability of latex-process chlorinated natural rubber by uniformly mixing a heat stabilizer composition with chlorinated natural rubber, reduces the amount of hydrogen chloride released by 40%-60%, extends the induction time of hydrogen chloride release by 5-10 minutes, and reduces the amount of conjugated double bonds formed by 10%-20%.

[0004] However, despite the high efficiency of lead salts and organotin compounds in stabilizing polyvinyl chloride, their toxicity limits their widespread application. Furthermore, metal soaps, especially zinc soaps, are prone to "zinc burn" when in use: when the zinc content in the PVC formula is too high, the zinc soap (as the core component of the calcium-zinc composite heat stabilizer) displaces the active chlorine and absorbs HCl, generating a Lewis acid metal chloride (ZnCl2). This product, in turn, promotes the dehydrochlorination reaction, causing the PVC to undergo a rapid degradation, a phenomenon known as zinc burn.

[0005] Therefore, it is urgent to develop a heat stabilizer that does not contain lead salts and organotin compounds and can avoid the zinc burning phenomenon. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a thermal stabilizer having good long-term stability.

[0007] One of the purposes of the present invention is achieved by the following technical solution:

[0008] A heat stabilizer, comprising the following components, in parts by weight: 20-40 parts of zinc stearate, 36-50 parts of an auxiliary stabilizer, 2-5 parts of a PVC crosslinking agent, and 1-3 parts of a crosslinking aid; the auxiliary stabilizer has the following structure:

[0009]

[0010] Furthermore, the preparation of the auxiliary stabilizer comprises the following steps:

[0011] (1) Under an inert atmosphere, 4-bromophenylurea and tetraethylenepentamine were added to 1,4-dioxane and heated for reaction, and then treated to obtain intermediate 1; the structure of intermediate 1 is:

[0012]

[0013] (2) Under an inert atmosphere, intermediate 1, copper iodide, 3,4,7,8-tetramethyl-1,10-phenanthroline, cesium carbonate and 2-(4-hydroxy-3-methoxyphenyl)acetaldehyde were added to toluene and heated for reaction, and then treated to obtain intermediate 2; the structure of intermediate 2 is:

[0014]

[0015] (3) The intermediate 2, 5-bromo-6-aminouracil and magnesium sulfate are added to dichloromethane and stirred for reaction, and the auxiliary stabilizer is prepared after treatment.

[0016] Furthermore, the molar ratio of 4-bromophenylurea to tetraethylenepentamine in step (1) is 1:(0.45-0.5).

[0017] Furthermore, in step (2), the molar ratio of the intermediate 1, 2-(4-hydroxy-3-methoxyphenyl)acetaldehyde, copper iodide, 3,4,7,8-tetramethyl-1,10-phenanthroline, and cesium carbonate is 1:(1.3-1.5):(0.05-0.08):(0.1-0.16):(1.3-1.5).

[0018] Furthermore, in step (3), the molar ratio of the intermediate 2, 5-bromo-6-aminouracil, and magnesium sulfate is 1: (1-1.2): (0.02-0.04).

[0019] Furthermore, the temperature of the heating reaction in step (1) is 100-110° C., and the time is 24-36 hours.

[0020] Furthermore, the heating reaction in step (2) is carried out at a temperature of 100 to 110° C. and for a time of 24 to 36 hours.

[0021] Furthermore, the stirring reaction time in step (3) is 12 to 18 hours.

[0022] Furthermore, the PVC crosslinking agent is dicumyl peroxide, and the crosslinking auxiliary agent is at least one of triallyl isocyanurate and trimethylolpropane triacrylate.

[0023] A second object of the present invention is to provide a method for preparing a heat stabilizer.

[0024] The second object of the present invention is achieved by adopting the following technical solution:

[0025] According to the parts by weight, zinc stearate, an auxiliary stabilizer, a crosslinking agent and a crosslinking aid are weighed and mixed uniformly to obtain the heat stabilizer.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention designs and synthesizes an auxiliary stabilizer and combines it with zinc stearate, significantly improving the long-term stability of PVC products and ensuring their excellent thermal stability. The auxiliary stabilizer and zinc stearate exhibit a synergistic effect, stemming from the reaction between the auxiliary stabilizer and ZnCl2 (derived from the product of the reaction between zinc stearate and PVC). Specifically, the auxiliary stabilizer acts as a chelating agent for metal chlorides, forming an inert complex that delays the "zinc burn" phenomenon in PVC. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a preparation flow chart of the present invention;

[0029] Figure 2 This is a color change diagram of the oven aging test of the present invention. DETAILED DESCRIPTION

[0030] Below, in conjunction with the accompanying drawings and specific embodiments, the present invention is further described. It should be noted that, under the premise of no conflict, the various embodiments described below or the various technical features can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0031] Example 1

[0032] A heat stabilizer comprises the following components, calculated in parts by weight: 30 parts of zinc stearate, 36 parts of an auxiliary stabilizer, 3 parts of dicumyl peroxide, and 2 parts of triallyl isocyanurate.

[0033] The preparation process of the auxiliary stabilizer is as follows Figure 1 As shown, the following steps are included:

[0034] (1) Under nitrogen atmosphere, 4-bromophenylurea (100 mmol) and tetraethylenepentamine (50 mmol) were added to 250 mL of 1,4-dioxane, stirred evenly, and then heated to 110°C for 24 hours. After the reaction, the reaction mixture was filtered to collect the filter cake, which was washed with deionized water and slurried with methanol (1 g of filter cake corresponds to 3.5 mL of methanol). The mixed system was filtered and the filter cake was collected and dried to obtain intermediate 1.

[0035] (2) Under nitrogen atmosphere, copper iodide (CuI, 5 mmol), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4Phen, 10 mmol), cesium carbonate (Cs2CO3, 150 mmol), intermediate 1 (100 mmol) and 2-(4-hydroxy-3-methoxyphenyl)acetaldehyde (150 mmol) were added to 300 mL of toluene, stirred evenly, and then heated to 110°C and reacted for 30 h; the reaction solution was cooled to room temperature, diluted with ethyl acetate and filtered, the filtrate was collected, concentrated and purified by chromatography (the volume ratio of n-heptane to ethyl acetate in the eluent was 7:1) to obtain intermediate 2;

[0036] (3) Intermediate 2 (100 mmol), 5-bromo-6-aminouracil (110 mmol) and magnesium sulfate (3 mmol) were added to 500 mL of dichloromethane and reacted at 28°C for 12 h. After the reaction, the reaction solution was dried, concentrated, and column-filtered (1 wt% acetic acid was added to the eluent, and the volume ratio of petroleum ether to ethyl acetate in the eluent was 7:1) to obtain an auxiliary stabilizer.

[0037] MS results of auxiliary stabilizer: [M] m / z: 1129.24, ESI-MS (m / z): 1129.24; NMR results of auxiliary stabilizer: 1 H NMR (C 48 H 53 Br2N 13 O 10, 400MHz, DMSO-d6): δ10.98 (s, 2H), 10.81 (s, 2H), 8.70 (t, 2H), 8.34 (s, 2H), 7.51 (d, 4H), 7.00 (m , 6H), 6.03(s, 2H), 3.83(s, 6H), 3.48(m, 4H), 3.39(d, 4H), 2.66(m, 4H), 2.53(s, 8H), 1.5(s, 3H).

[0038] This embodiment also provides a method for preparing the above-mentioned heat stabilizer, comprising the following steps: weighing zinc stearate, an auxiliary stabilizer, dicumyl peroxide, and triallyl isocyanurate in the aforementioned parts by weight and mixing them uniformly to obtain the heat stabilizer.

[0039] Example 2

[0040] A heat stabilizer comprises the following components, calculated in parts by weight: 20 parts of zinc stearate, 40 parts of an auxiliary stabilizer, 2 parts of dicumyl peroxide, and 1 part of trimethylolpropane triacrylate.

[0041] The preparation process of the auxiliary stabilizer is as follows Figure 1 As shown, the following steps are included:

[0042] (1) Under nitrogen atmosphere, 4-bromophenylurea (100 mmol) and tetraethylenepentamine (45 mmol) were added to 250 mL of 1,4-dioxane, stirred evenly, and then heated to 105°C for 32 hours. After the reaction, the reaction mixture was filtered to collect the filter cake, which was washed with deionized water and slurried with methanol (1 g of filter cake corresponds to 3.5 mL of methanol). The mixed system was filtered and the filter cake was collected and dried to obtain intermediate 1.

[0043] (2) Under nitrogen atmosphere, copper iodide (CuI, 8 mmol), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4Phen, 16 mmol), cesium carbonate (Cs2CO3, 140 mmol), intermediate 1 (100 mmol) and 2-(4-hydroxy-3-methoxyphenyl)acetaldehyde (140 mmol) were added to 300 mL of toluene, stirred evenly, and then heated to 105°C and reacted for 24 h; the reaction solution was cooled to room temperature, diluted with ethyl acetate and filtered, the filtrate was collected, concentrated and purified by chromatography (the volume ratio of n-heptane to ethyl acetate in the eluent was 7:1) to obtain intermediate 2;

[0044] (3) Intermediate 2 (100 mmol), 5-bromo-6-aminouracil (120 mmol) and magnesium sulfate (4 mmol) were added to 500 mL of dichloromethane and reacted at 32°C for 12 h. After the reaction, the reaction solution was dried, concentrated, and column-filtered (1 wt% acetic acid was added to the eluent, and the volume ratio of petroleum ether to ethyl acetate in the eluent was 7:1) to obtain an auxiliary stabilizer.

[0045] This embodiment also provides a method for preparing the above-mentioned heat stabilizer, comprising the following steps: weighing zinc stearate, an auxiliary stabilizer, dicumyl peroxide, and trimethylolpropane triacrylate in the aforementioned parts by weight and mixing them uniformly to obtain the heat stabilizer.

[0046] Example 3

[0047] A heat stabilizer comprises the following components, calculated in parts by weight: 40 parts of zinc stearate, 20 parts of an auxiliary stabilizer, 5 parts of dicumyl peroxide, and 3 parts of trimethylolpropane triacrylate.

[0048] The preparation process of the auxiliary stabilizer is as follows Figure 1 As shown, the following steps are included:

[0049] (1) Under nitrogen atmosphere, 4-bromophenylurea (100 mmol) and tetraethylenepentamine (48 mmol) were added to 250 mL of 1,4-dioxane, stirred evenly, and then heated to 100°C for reaction for 36 hours. After the reaction, the reaction solution was filtered to collect the filter cake, which was washed with deionized water and slurried with methanol (1 g of filter cake corresponds to 3.5 mL of methanol). The mixed system was filtered and the filter cake was collected and dried to obtain intermediate 1.

[0050] (2) Under nitrogen atmosphere, copper iodide (CuI, 6.5 mmol), 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4Phen, 13 mmol), cesium carbonate (Cs2CO3, 130 mmol), intermediate 1 (100 mmol) and 2-(4-hydroxy-3-methoxyphenyl)acetaldehyde (130 mmol) were added to 300 mL of toluene, stirred evenly, and then heated to 100°C and reacted for 36 h; the reaction solution was cooled to room temperature, diluted with ethyl acetate and filtered, the filtrate was collected, concentrated and purified by chromatography (the volume ratio of n-heptane to ethyl acetate in the eluent was 7:1) to obtain intermediate 2;

[0051] (3) Intermediate 2 (100 mmol), 5-bromo-6-aminouracil (100 mmol) and magnesium sulfate (2 mmol) were added to 500 mL of dichloromethane and reacted at 25° C. for 18 h. After the reaction, the reaction solution was dried, concentrated, and column-filtered (1 wt % acetic acid was added to the eluent, and the volume ratio of petroleum ether to ethyl acetate in the eluent was 7:1) to obtain an auxiliary stabilizer.

[0052] This embodiment also provides a method for preparing the above-mentioned heat stabilizer, comprising the following steps: weighing zinc stearate, an auxiliary stabilizer, dicumyl peroxide, and trimethylolpropane triacrylate in the aforementioned parts by weight and mixing them uniformly to obtain the heat stabilizer.

[0053] Comparative Example 1

[0054] A heat stabilizer, which differs from Example 1 in that zinc stearate is omitted.

[0055] Comparative Example 2

[0056] A heat stabilizer, which differs from Example 1 in that the auxiliary antioxidant is omitted.

[0057] Test example

[0058] 100 parts of PVC resin, 10 parts of dioctyl phthalate, 15 parts of calcium carbonate, and 2 parts of the heat stabilizer prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were thoroughly mixed in mortar and processed on an open double-wheel mill at 180° C. for 5 minutes to produce a PVC sheet with a thickness of approximately 1 mm. The Congo red test and oven aging test were used to verify the effect of the heat stabilizer on the thermal stability of the PVC sheet.

[0059] Test Example 1

[0060] According to GB.T2917.1-2002, "Determination of hydrogen chloride and any other acidic products released by blends and products based on vinyl chloride homopolymers and copolymers at elevated temperatures—Congo red method," the prepared PVC sample was cut into granular samples measuring 2 mm × 2 mm × 1 mm and placed in a 50 mm test tube. The tube was sealed with a stopper and secured with Congo red test paper. The sealed tube was placed in an oil bath at 180°C, and the time it took for the test paper to turn blue was recorded; this time represents the thermal stability time of the sample. The results are shown in Table 1.

[0061] Table 1 Thermal stabilization time

[0062]

[0063] As shown in Table 1, Example 1, which uses a combination of an auxiliary antioxidant and zinc stearate, takes the longest time for the PVC sample to change color with Congo red and has the best thermal stability, followed by Examples 2 and 3. Compared with Examples 1-3, Comparative Example 1, which omits zinc stearate, and Comparative Example 2, which omits the auxiliary antioxidant, takes a shorter time to change color, indicating that the auxiliary antioxidant and zinc stearate can synergistically improve the thermal stability of PVC resin.

[0064] Test Example 2

[0065] Oven aging test: Cut the mixed PVC sample into 4cm×2cm pieces and put them into a 180℃ oven. Take out a piece every 10 minutes, take pictures, record and compare the color change of PVC samples with different types of stabilizers over time. Figure 2 shown.

[0066] Depend on Figure 2 It can be seen that when the auxiliary antioxidant is omitted in Comparative Example 2 and only zinc stearate is used as the antioxidant, although the PVC strip has a good initial color, it completely turns black after 10 minutes and has the worst thermal stability. When zinc stearate is omitted in Comparative Example 1 and only the auxiliary antioxidant prepared by the present invention is used as the core component, the PVC sample turns brown-black after 90 minutes and has poor thermal stability. In contrast, Examples 1 to 3 use zinc stearate and the auxiliary antioxidant as the core component, which greatly extends the long-term stability of the PVC strip. This is because after zinc stearate reacts with PVC to form ZnCl2, the auxiliary stabilizer can react with ZnCl2 as a chelating agent for metal chloride, thereby delaying the "zinc burning" phenomenon of PVC by forming an inert complex. Therefore, the auxiliary antioxidant of the present invention and zinc stearate can synergistically improve the long-term thermal stability of PVC resin.

[0067] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A heat stabilizer, characterized in that The composition comprises the following components in parts by weight: 20 to 40 parts of zinc stearate, 36 to 50 parts of an auxiliary stabilizer, 2 to 5 parts of a PVC crosslinking agent, and 1 to 3 parts of a crosslinking aid; the auxiliary stabilizer has the following structure:

2. The heat stabilizer according to claim 1, characterized in that The preparation of the auxiliary stabilizer comprises the following steps: (1) Under an inert atmosphere, 4-bromophenylurea and tetraethylenepentamine were added to 1,4-dioxane and heated for reaction, and then treated to obtain intermediate 1; the structure of intermediate 1 is: (2) Under an inert atmosphere, intermediate 1, copper iodide, 3,4,7,8-tetramethyl-1,10-phenanthroline, cesium carbonate and 2-(4-hydroxy-3-methoxyphenyl)acetaldehyde were added to toluene and heated for reaction, and then treated to obtain intermediate 2; the structure of intermediate 2 is: (3) The intermediate 2, 5-bromo-6-aminouracil and magnesium sulfate are added to dichloromethane and stirred for reaction, and the auxiliary stabilizer is prepared after treatment.

3. The heat stabilizer according to claim 2, characterized in that The molar ratio of 4-bromophenylurea to tetraethylenepentamine in step (1) is 1:(0.45-0.5).

4. The heat stabilizer according to claim 2, characterized in that The molar ratio of the intermediate 1, 2-(4-hydroxy-3-methoxyphenyl)acetaldehyde, copper iodide, 3,4,7,8-tetramethyl-1,10-phenanthroline and cesium carbonate in step (2) is 1:(1.3-1.5):(0.05-0.08):(0.1-0.16):(1.3-1.5).

5. The heat stabilizer according to claim 2, characterized in that In step (3), the molar ratio of the intermediate 2, 5-bromo-6-aminouracil, and magnesium sulfate is 1: (1-1.2): (0.02-0.04).

6. The heat stabilizer according to claim 2, characterized in that The heating reaction temperature in step (1) is 100-110° C. and the time is 24-36 hours.

7. The heat stabilizer according to claim 2, characterized in that The heating reaction temperature in step (2) is 100-110° C. and the time is 24-36 hours.

8. The heat stabilizer according to claim 2, characterized in that The stirring reaction time in step (3) is 12 to 18 hours.

9. The heat stabilizer according to claim 1, characterized in that The PVC crosslinking agent is dicumyl peroxide, and the crosslinking auxiliary agent is at least one of triallyl isocyanurate and trimethylolpropane triacrylate.

10. The method for preparing a heat stabilizer according to any one of claims 1 to 9, characterized in that: The following steps are involved: According to the parts by weight, zinc stearate, an auxiliary stabilizer, a crosslinking agent and a crosslinking aid are weighed and mixed uniformly to obtain the heat stabilizer.

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