Heat stabilizer and preparation method thereof

Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a heat stabilizer and a preparation method thereof. The heat stabilizer is prepared from 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 cross-linking agent and 1 to 3 parts of a cross-linking aid. The invention designs and synthesizes an auxiliary stabilizer, and the auxiliary stabilizer is combined with zinc stearate, so that the long-term stability of a PVC product can be remarkably improved, and the excellent thermal stability of the PVC product is ensured. The auxiliary stabilizer and the zinc stearate have a synergistic effect, the synergistic effect is derived from a reaction between the auxiliary stabilizer and ZnCl2 (derived from a product obtained after the zinc stearate and PVC act), the auxiliary stabilizer can serve as a chelating agent of metal chloride, and the zinc burning phenomenon of PVC is delayed by forming an inert complex.

Description

Technical Field

[0001] The 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] As the most important additive for polyvinyl chloride (PVC), heat stabilizers play a key role in inhibiting thermal degradation reactions caused by inherent structural defects in polymer chains during thermal processing. The mechanism of action of heat stabilizers is generally believed to be to enhance thermal stability by absorbing hydrogen chloride released during the degradation of PVC or reacting with unstable chlorine atoms such as allyl chloride and tertiary chlorine atoms. Currently, the main commercial stabilizers used for PVC include lead salts, organotin compounds, metal soaps and organic stabilizers.

[0003] CN109929191A discloses a high-efficiency heat stabilizer, which is made of the following components by weight: 0.15-0.23 parts of inhibitor, 20-45 parts of 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 lubricant, 5-8 parts of zinc stearate, 4-7 parts of phosphite, 5-16 parts of tribasic lead sulfate, 1-3 parts of monoglyceride, and 0.6-1.2 parts of superdispersant; the patent is made by heating, mixing and stirring the components, which improves the heat stabilization effect, ensures good color stability and heat resistance, and effectively reduces the pollution in use and production links. CN1318492C discloses a heat stabilizer composition for latex-process chlorinated natural rubber, which contains hindered phenol, stearate, organic tin compound and epoxidized vegetable oil. This patent significantly improves the thermal stability of latex-process chlorinated natural rubber by uniformly mixing the 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 issues limit their widespread application. In addition, metal soaps, especially zinc soaps, are very likely to cause the "zinc burn" phenomenon when they are in action: when the zinc content in the PVC formula is too high, zinc soap (as the core component of the calcium-zinc composite heat stabilizer) will generate Lewis acid metal chloride (ZnCl2) after replacing active chlorine and absorbing HCl, which in turn can promote the de-HCl reaction, causing PVC to undergo malignant degradation in a very short time, namely the zinc burn phenomenon.

[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, 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 are added to 1,4-dioxane and heated for reaction, and then treated to obtain an intermediate 1; the structure of the 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 are 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 temperature of the heating reaction in step (2) is 100-110° C., and the time is 24-36 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 aid 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, auxiliary stabilizer, crosslinking agent and crosslinking aid are weighed and mixed evenly 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, which significantly improves the long-term stability of PVC products and ensures its excellent thermal stability. The auxiliary stabilizer of the present invention has a synergistic effect with zinc stearate, and the synergistic effect is derived from the reaction between the auxiliary stabilizer and ZnCl2 (derived from the product of the reaction of zinc stearate and PVC). Specifically, the auxiliary stabilizer can be used as a chelating agent for metal chlorides to delay the "zinc burning" phenomenon of PVC by forming an inert complex. 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 embodiments described below or the technical features can be arbitrarily combined to form new embodiments. The specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The 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, measured 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 reaction for 24 hours; after the reaction, the reaction solution was filtered to collect the filter cake, the filter cake was washed with deionized water, and then 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, 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 according to the above-mentioned parts by weight and mixing them evenly to obtain the heat stabilizer.

[0039] Example 2

[0040] A heat stabilizer comprises the following components, measured 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 reaction for 32 hours; after the reaction, the reaction solution was filtered to collect the filter cake, the filter cake was washed with deionized water, and then 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, 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, auxiliary stabilizer, dicumyl peroxide and trimethylolpropane triacrylate according to the above-mentioned parts by weight and mixing them evenly to obtain the heat stabilizer.

[0046] Example 3

[0047] A heat stabilizer comprises the following components, measured 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, the filter cake was washed with deionized water, and then 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, 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, auxiliary stabilizer, dicumyl peroxide and trimethylolpropane triacrylate according to the above-mentioned parts by weight and mixing them evenly 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 fully mixed in mortar, and processed on an open double-wheel mill at 180° C. for 5 minutes to prepare a PVC sheet with a thickness of about 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 high temperatures - Congo red method", the prepared PVC sample was cut into granular samples of 2mm×2mm×1mm and placed in a test tube with a sample height of 50mm. The test tube was sealed with a stopper to fix the Congo red test paper, and the sealed test tube was placed in an oil bath at 180℃, and the time when the test paper turned blue was recorded, which was the thermal stability time of the sample. The specific results are shown in Table 1.

[0061] Table 1 Thermal stability time

[0062]

[0063] As shown in Table 1, Example 1 uses a secondary antioxidant and zinc stearate compound, and the Congo red discoloration time of the PVC sample is the longest, and the thermal stability effect is the best, followed by Examples 2 and 3. Compared with Examples 1 to 3, the sample discoloration time is shorter after Comparative Example 1 omits zinc stearate and Comparative Example 2 omits the secondary antioxidant, which shows that the secondary 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, 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 the aging time. The specific results are as follows 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 an antioxidant, the PVC strip has a good initial color, but it completely turns black in 10 minutes, and the thermal stability is the worst. 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 and black in 90 minutes, and the thermal stability is poor. While Examples 1 to 3 compound zinc stearate and auxiliary antioxidants as core components, which greatly prolongs the long-term stability of the PVC strip. This is because after zinc stearate reacts with PVC to generate ZnCl2, the auxiliary stabilizer can react with ZnCl2 as a chelating agent of metal chloride, and delays 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-mentioned 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 substitutions made by technicians in this field on the basis of the present invention shall 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 by weight: 20 to 40 parts of zinc stearate, 36 to 50 parts of auxiliary stabilizer, 2 to 5 parts of PVC crosslinking agent, and 1 to 3 parts of crosslinking auxiliary agent; the structure of the auxiliary stabilizer is:

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 are added to 1,4-dioxane and heated for reaction, and then treated to obtain an intermediate 1; the structure of the 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 are 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 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).

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 aid 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 weight proportions, zinc stearate, auxiliary stabilizer, crosslinking agent and crosslinking aid are weighed and mixed evenly to obtain the heat stabilizer.

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