Heat-resistant calcium-zinc stabilizer for PVC and preparation method thereof

Abstract

The application relates to the technical field of plastic additives, in particular to a heat-resistant calcium-zinc stabilizer for PVC and a preparation method thereof. The preparation raw material of the calcium-zinc stabilizer comprises the following components in parts by weight: modified calcium salt 4-6 parts, modified zinc salt 1-1.5 parts, cashew phenol-SiO2 1-1.5 parts, hydrotalcite 0.5-1 part, pentaerythritol 0.2-0.3 part, beta-diketone 0.8-1.2 part and antioxidant 0.5-0.7 part. The prepared calcium-zinc stabilizer can significantly improve the heat stability of PVC.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic additives, in particular to a heat-resistant calcium-zinc stabilizer for PVC and a preparation method thereof. BACKGROUND

[0002] Polyvinyl chloride (PVC) is a common plastic material, and its products have good physical and chemical properties, and are widely used in industrial, construction, agricultural, daily life, packaging, power, public utilities and other fields. However, when PVC is processed under high temperature and high shear conditions, it is easy to lose hydrogen chloride on the molecule, leading to degradation of the polymer, discoloration of the product and decrease of the mechanical properties of the product, affecting the service life, so a heat stabilizer needs to be added during processing to improve its thermal stability. Traditional PVC heat stabilizers include lead salt heat stabilizers, organic tin heat stabilizers, organic antimony heat stabilizers and metal soap heat stabilizers. Although the lead salt heat stabilizer has excellent thermal stability, it is highly toxic. The organic tin stabilizer is widely used in transparent PVC product production, but it is expensive and has an odor. The organic antimony stabilizer is not only toxic but also has poor weather resistance and product transparency. Metal soaps usually need to be used in combination, and are prone to precipitation during processing. Rare earth composite heat stabilizers have good comprehensive performance, but are not suitable for large-scale application. Traditional calcium-zinc heat stabilizers, such as composite calcium stearate zinc (CaSt2 / ZnSt2), generally have poor thermal stability and are prone to zinc burning of the product. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a heat-resistant calcium-zinc stabilizer for PVC and a preparation method thereof.

[0004] The present application is realized by the following technical solutions:

[0005] A heat-resistant calcium-zinc stabilizer for PVC, the preparation raw materials include the following components in parts by weight: modified calcium salt 4-6 parts, modified zinc salt 1-1.5 parts, cardanol-SiO2 1-1.5 parts, hydrotalcite 0.5-1 part, pentaerythritol 0.2-0.3 part, beta-diketone 0.8-1.2 part, antioxidant 0.5-0.7 part.

[0006] Further, the antioxidant is one or more of antioxidant 164, antioxidant 264, antioxidant 1010, antioxidant 1076, and antioxidant JA-80.

[0007] Further, the preparation raw materials of the modified calcium salt include the following components in parts by weight: methyl syringate 8-12 parts, hexachlorocyclotriphosphazene (HCCP) 2-3 parts, calcium chloride 4-6 parts.

[0008] Further, the preparation method of the modified calcium salt includes the following steps:

[0009] L1. Methyl eugenol was added into tetrahydrofuran (THF) and mixed to obtain a mixed solution, HCCP was dissolved in THF, potassium carbonate was added, and the mixed solution was added dropwise within 1 h, after dropwise addition was completed, 70℃, 600-800 rpm stirring, reflux reaction for 12 h, cooling to room temperature, rotary evaporation to remove the solvent, washed with ethanol and deionized water, and vacuum dried;

[0010] L2. NaOH was prepared into an aqueous solution of 1.8 mmol / mL, the product obtained in step L1 was added into 15 times weight volume of THF, and was added dropwise into the NaOH aqueous solution within 1 h, after dropwise addition was completed, 70℃ reflux stirring for 1.5 h, rotary evaporation to remove the solvent, 10 times weight volume of deionized water was added, 1 mol / L hydrochloric acid was used to adjust the pH to 2, stirring for 8-10 h, 8000 rpm centrifugation for 10-15 min, the precipitate was washed with distilled water and ethanol, and dried.

[0011] L3. Calcium chloride was prepared into an aqueous solution of 0.1 g / mL, the product obtained in step L2 and sodium bicarbonate were added into deionized water, 65℃ reaction for 2 h, the aqueous solution of calcium chloride was added dropwise, after dropwise addition was completed, 70℃ reaction for 3 h, 8000 rpm centrifugation for 10-15 min, deionized water and ethanol washing, and vacuum drying to obtain a modified calcium salt.

[0012] Further, in step L1, the mass concentration of the methyl eugenol in THF is 0.1 mg / mL.

[0013] Further, in step L1, the mass concentration of the HCCP in THF is 50 mg / mL.

[0014] Further, in step L1, the mass ratio of the potassium carbonate to the HCCP is 5:1.

[0015] Further, in step L2, the mass ratio of the NaOH to the HCCP is 36:25.

[0016] Further, in step L3, the mass ratio of the sodium bicarbonate to the calcium chloride is 3:4.

[0017] Further, in step L3, the mass concentration of the sodium bicarbonate in deionized water is 20 mg / mL.

[0018] Further, the preparation method of the modified zinc salt is the same as that of the modified calcium salt, except that the raw material calcium chloride is replaced by zinc sulfate heptahydrate 10-15 parts.

[0019] Further, the preparation raw material of the cardanol-SiO2 includes the following components in weight parts: 2,2'-(1,2-ethanediyldioxy)bisethanethiol (DODT) 2-3 parts, cardanol 7-10 parts, 3-chloropropylamine hydrochloride 3-4.5 parts, 3-isocyanatopropyltrimethoxysilane (IPTS) 4.5-6.8 parts, and tetraethyl orthosilicate (TEOS) 20-30 parts.

[0020] Further, the preparation method of the cardanol-SiO2 includes the following steps:

[0021] V1. DODT was added to ethyl acetate and stirred to dissolve under a nitrogen atmosphere, and heated to 70°C to obtain a DODT solution. Cardanol and azobisisobutyronitrile (AIBN) were dissolved in ethyl acetate and added dropwise to the DODT solution, and reacted at 70°C for 24 h. The solvent was removed by rotary evaporation, washed with anhydrous ethanol, and dried;

[0022] V2. The product obtained in step V1 and sodium hydroxide were mixed in N,N-dimethylformamide (DMF), and nitrogen was introduced for 10 min. After stirring for 1 h, 3-chloropropylamine hydrochloride was added, and the mixture was stirred at room temperature for 36 h. Ethyl acetate was added, and the mixture was washed with deionized water and saturated sodium chloride solution. The organic layer was dried with anhydrous magnesium sulfate, filtered, and the filtrate was distilled under reduced pressure to remove ethyl acetate;

[0023] V3. IPTS was mixed in toluene to obtain an IPTS solution, and the product obtained in step V2 and dibutyltin dilaurate (DBTDL) were mixed in toluene. The mixture was added dropwise to the IPTS solution within 30 min, and reacted at 80°C for 6 h. The reaction solution was washed with deionized water, and the organic layer was distilled under reduced pressure to remove the solvent;

[0024] V4. Anhydrous ethanol and concentrated ammonia water were mixed to obtain solution A. TEOS was dissolved in anhydrous ethanol to obtain solution B. Solution B was added dropwise to solution A, and reacted at 25°C for 6 h. The product obtained in step V3 was added, and the mixture was further reacted for 18 h. The mixture was centrifuged at 8000 rpm for 8-12 min. The precipitate was washed with toluene, water, and ethanol, and dried under vacuum to obtain cardanol-SiO2.

[0025] Further, in step V1, the mass concentration of DODT in ethyl acetate is 0.2-0.3 g / mL.

[0026] Further, in step V1, the mass concentration of cardanol in ethyl acetate is 0.1 g / mL.

[0027] Further, in step V1, the amount of AIBN is 2-2.5 wt% of the mass of DODT.

[0028] Further, in step V2, the mass ratio of sodium hydroxide to 3-chloropropylamine hydrochloride is 1:2-2.5.

[0029] Further, in step V2, the mass concentration of 3-chloropropylamine hydrochloride in DMF is 20-30 mg / mL.

[0030] Further, in step V2, the volume ratio of ethyl acetate to DMF is 1:1.

[0031] Further, in step V3, the mass concentration of IPTS in toluene is 0.1 g / mL.

[0032] Further, in step V3, the amount of DBTDL is 0.8-1wt% of IPTS.

[0033] Further, in step V3, the mass concentration of DBTDL in toluene is 1 mg / mL.

[0034] Further, in step V4, the volume ratio of anhydrous ethanol to concentrated ammonia water is 80:7.

[0035] Further, in step V4, the mass concentration of TEOS in anhydrous ethanol is 0.25 g / mL.

[0036] Further, in step V4, the volume ratio of anhydrous ethanol in solution A to solution B is 2:1.

[0037] Further, the application also provides a preparation method of the heat-resistant calcium-zinc stabilizer for PVC, comprising the following steps: mixing modified calcium salt, modified zinc salt, cardanol-SiO2 and hydrotalcite at 800-1200 r / min for 10-15 min, adding pentaerythritol and beta-diketone, mixing at 600-800 r / min for 10-15 min, adding antioxidant, mixing at 400-600 r / min for 5-10 min, to obtain the heat-resistant calcium-zinc stabilizer for PVC.

[0038] Compared with the prior art, the application has the following beneficial effects:

[0039] The application provides a heat-resistant calcium-zinc stabilizer for PVC and a preparation method thereof. By the synergistic effect of modified calcium salt, modified zinc salt, cardanol-SiO2 and other auxiliary components, the heat stability of PVC is significantly improved, and the mechanical property retention rate of the product after heat aging is improved. The modified calcium salt is prepared, and hexachlorocyclotriphosphazene (HCCP) is used as a stable skeleton. HCCP has a rigid cyclic phosphazene structure, high P=N bond energy and excellent thermal stability. The substitution reaction of the phenolic hydroxyl group of methyl eugenate and the chlorine on the HCCP occurs to form a stable P-O-aryl bond, and the methyl eugenate is anchored to the highly stable phosphazene ring. The aromatic ring itself has a certain steric hindrance and conjugation effect, which helps to improve the overall stability of the structure. The ester group of methyl eugenate is hydrolyzed into sodium carboxylate (-COONa), and reacts with calcium chloride (or zinc sulfate). The calcium / zinc ion is coordinated to the organic structure through the carboxylate group. The phosphorus (P) and nitrogen (N) atoms on the HCCP phosphazene ring have the ability to absorb HCl generated by PVC degradation, and the calcium / zinc carboxylate itself is also an effective HCl absorbent. The zinc ion (or calcium ion) is connected to the phosphazene-aromatic ring composite structure through the carboxylate group, which improves the stability and improves the long-term thermal stability. The cardanol-SiO2 is prepared. The double bond of cardanol reacts with DODT to form a thioether bond through ene-thiol click reaction. The thioether bond itself has good thermal stability. The phenolic hydroxyl group of cardanol reacts with 3-chloropropylamine hydrochloride to introduce an amino group. The isocyanate group of IPTS reacts with the amino group to form a urea bond. The functionalized cardanol derivative is covalently bonded to IPTS. The silane group of IPTS reacts with SiO2 formed by hydrolysis of tetraethyl orthosilicate (TEOS) to form a condensation reaction. The organic part is anchored on the surface of inorganic SiO2 nanoparticles. The long alkyl structure provided by cardanol can improve the compatibility of SiO2 with the PVC matrix and promote dispersion. SiO2 can physically block heat transfer and improve heat resistance. The structure design of the modified calcium-zinc salt, the functional modification of cardanol-SiO2 and the synergistic cooperation of the auxiliary components improve the thermal stability of PVC. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only a part of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0041] Figure 1 Static heat stability of the calcium-zinc stabilizer described in examples 1-3 and comparative examples 1-3 of the present application;

[0042] Figure 2The Congo red test results of the calcium-zinc stabilizers described in the embodiments 1-3 and comparative examples 1-3 of the present application;

[0043] Figure 3 The mechanical property retention test results of the calcium-zinc stabilizers described in the embodiments 1-3 and comparative examples 1-3 of the present application;

[0044] Figure 4 The scanning electron microscope images of the cardanol-SiO2 and unmodified SiO2 described in the embodiments 1 and comparative example 1 of the present application. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with specific embodiments, but the present application is not limited to the following embodiments. It should be noted that, unless otherwise specified, the chemical reagents involved in the present application are purchased through commercial channels.

[0046] Embodiment 1: A heat-resistant calcium-zinc stabilizer for PVC, the preparation raw materials include the following components by weight: modified calcium salt 6 parts, modified zinc salt 1.5 parts, cardanol-SiO2 1.5 parts, hydrotalcite 1 part, pentaerythritol 0.3 part, β-diketone 1.2 part, antioxidant 1010 0.7 part.

[0047] The preparation raw materials of the modified calcium salt include the following components by weight: methyl syringate 12 parts, hexachlorocyclotriphosphazene (HCCP) 3 parts, calcium chloride 6 parts.

[0048] The preparation method of the modified calcium salt includes the following steps:

[0049] L1. Methyl syringate 12 g was added to tetrahydrofuran (THF) 120 mL and mixed uniformly to obtain a mixed solution, HCCP 3 g was dissolved in THF 60 mL, potassium carbonate 15 g was added, and the mixed solution was added dropwise within 1 h, after dropwise addition, 70℃, 800 rpm stirring, reflux reaction for 12 h, cooling to room temperature, rotary evaporation to remove the solvent, washing with ethanol and deionized water, and vacuum drying;

[0050] L2. 4.32 g of NaOH was prepared into an aqueous solution of 1.8 mmol / mL, the product obtained in step L1 was added to 15 times the weight volume of THF, and was added dropwise to the NaOH aqueous solution within 1 h, after dropwise addition, 70℃ reflux stirring for 1.5 h, rotary evaporation to remove the solvent, adding 10 times the weight volume of deionized water, adjusting the pH to 2 with 1 mol / L hydrochloric acid, stirring for 10 h, 8000 rpm centrifugation for 15 min, washing the precipitate with distilled water and ethanol, and drying;

[0051] L3. Prepare a 0.1 g / mL aqueous solution of calcium chloride 6 g, add the product obtained in step L2 and sodium bicarbonate 4.5 g to deionized water 225 mL, and react at 65°C for 2 h. Add the aqueous solution of calcium chloride dropwise, and react at 70°C for 3 h after the dropwise addition is complete. Centrifuge at 8000 rpm for 15 min, wash with deionized water and ethanol, and dry in a vacuum to obtain the modified calcium salt.

[0052] The method for preparing the modified zinc salt is the same as that for preparing the modified calcium salt, except that the raw material calcium chloride is replaced by zinc sulfate heptahydrate 15 g.

[0053] The raw materials for preparing cashew phenol-SiO2 include the following components in parts by weight: 2,2'-(1,2-ethanediyldioxy)bisethanethiol (DODT) 3 parts, cashew phenol 10 parts, 3-chloropropylamine hydrochloride 4.5 parts, 3-isocyanatopropyltrimethoxysilane (IPTS) 6.8 parts, and tetraethyl orthosilicate (TEOS) 30 parts.

[0054] The method for preparing cashew phenol-SiO2 includes the following steps:

[0055] V1. Add DODT 3 g to ethyl acetate 10 mL, stir to dissolve under a nitrogen atmosphere, and heat to 70°C to obtain a DODT solution. Dissolve cashew phenol 10 g and azobisisobutyronitrile (AIBN) 75 mg in ethyl acetate 100 mL, and add dropwise to the DODT solution. React at 70°C for 24 h, remove the solvent by rotary evaporation, wash with anhydrous ethanol, and dry;

[0056] V2. Mix the product obtained in step V1 and sodium hydroxide 1.8 g in N,N-dimethylformamide (DMF) 150 mL, pass nitrogen for 10 min, stir for 1 h, add 3-chloropropylamine hydrochloride 4.5 g, and stir to react at room temperature for 36 h. Add ethyl acetate 150 mL, wash with deionized water and saturated sodium chloride solution, dry the organic layer with anhydrous magnesium sulfate, filter, and remove the ethyl acetate from the filtrate by distillation under reduced pressure;

[0057] V3. Mix IPTS 6.8 g in toluene 68 mL to obtain an IPTS solution, and use an 80°C water bath. Mix the product obtained in step V2 and dibutyltin dilaurate (DBTDL) 68 mg in toluene 68 mL, and add dropwise to the IPTS solution within 30 min. React at 80°C for 6 h, wash the reaction solution with deionized water, and remove the solvent from the organic layer by distillation under reduced pressure;

[0058] V4. Mix 240 mL of anhydrous ethanol with 21 mL of concentrated ammonia to obtain solution A. Dissolve 30 g of TEOS in 120 mL of anhydrous ethanol to obtain solution B. Add solution B dropwise to solution A and react at 25 °C for 6 h. Add the product obtained in step V3 and continue the reaction for 18 h. Centrifuge at 8000 rpm for 12 min. Wash the precipitate with toluene, water, and ethanol, and dry under vacuum to obtain cashew phenol-SiO2.

[0059] This embodiment also provides a method for preparing the heat-resistant calcium-zinc stabilizer for PVC, comprising the following steps: mixing 6 g of modified calcium salt, 1.5 g of modified zinc salt, 1.5 g of cashew phenol-SiO2 and 1 g of hydrotalcite at 1200 r / min for 15 min, adding 0.3 g of pentaerythritol and 1.2 g of β-diketone, mixing at 800 r / min for 15 min, adding 0.7 g of antioxidant 1010, and mixing at 600 r / min for 10 min to obtain the heat-resistant calcium-zinc stabilizer for PVC.

[0060] Example 2: A heat-resistant calcium-zinc stabilizer for PVC, the raw materials for which are prepared include the following components in parts by weight: 4 parts modified calcium salt, 1 part modified zinc salt, 1 part cashew phenol-SiO2, 0.5 parts hydrotalcite, 0.2 parts pentaerythritol, 0.8 parts β-diketone, and 0.5 parts antioxidant 1010.

[0061] The raw materials for preparing modified calcium salts include the following components in parts by weight: methyl eugenol 8 parts, hexachlorocyclotriphosphazene (HCCP) 2 parts, and calcium chloride 4 parts.

[0062] The preparation method of modified calcium salt includes the following steps:

[0063] L1. Add 8 g of methyl eugenol to 80 mL of tetrahydrofuran (THF) and mix well to obtain a mixture. Dissolve 2 g of HCCP in 40 mL of THF, add 10 g of potassium carbonate, and add the mixture dropwise over 1 h. After the addition is complete, stir at 70 °C and 600 rpm and reflux for 12 h. Cool to room temperature, remove the solvent by rotary evaporation, wash with ethanol and deionized water, and dry under vacuum.

[0064] L2. Prepare an aqueous solution of 1.8 mmol / mL NaOH with 2.88 g of NaOH. Add the product obtained in step L1 to 15 times its weight volume of THF and add it dropwise to the NaOH aqueous solution over 1 h. After the addition is complete, reflux and stir at 70 °C for 1.5 h. Remove the solvent by rotary evaporation. Add 10 times its weight volume of deionized water and adjust the pH to 2 with 1 mol / L hydrochloric acid. Stir for 8 h, centrifuge at 8000 rpm for 10 min, wash the precipitate with distilled water and ethanol, and dry it.

[0065] L3. Prepare an aqueous solution of 0.1 g / mL with 4 g of calcium chloride. Add the product obtained in step L2 and 3 g of sodium bicarbonate to 150 mL of deionized water and react at 65℃ for 2 h. Add the calcium chloride aqueous solution dropwise. After the addition is complete, react at 70℃ for 3 h. Centrifuge at 8000 rpm for 10 min, wash with deionized water and ethanol, and vacuum dry to obtain the modified calcium salt.

[0066] The preparation method of modified zinc salt is the same as that of modified calcium salt, except that the raw material calcium chloride is replaced with 10 g of zinc sulfate heptahydrate.

[0067] The raw materials for preparing cashew phenol-SiO2 include the following components in parts by weight: 2,2'-(1,2-ethylenedioxydioxo)diethylthiol (DODT) 2 parts, cashew phenol 7 parts, 3-chloropropylamine hydrochloride 3 parts, 3-isocyanate-propyltrimethoxysilane (IPTS) 4.5 parts, and tetraethyl orthosilicate (TEOS) 20 parts.

[0068] The preparation method of cashew phenol-SiO2 includes the following steps:

[0069] V1. Add 2 g of DODT to 10 mL of ethyl acetate, stir and dissolve under a nitrogen atmosphere, heat to 70 °C to obtain DODT solution, dissolve 7 g of cashew phenol and 40 mg of azobisisobutyronitrile (AIBN) in 70 mL of ethyl acetate, add dropwise to DODT solution, react at 70 °C for 24 h, remove solvent by rotary evaporation, wash with anhydrous ethanol and dry.

[0070] V2. The product obtained in step V1 and 1.5 g of sodium hydroxide were added to 150 mL of N,N-dimethylformamide (DMF) and mixed well. Nitrogen gas was introduced for 10 min and stirred for 1 h. 3 g of 3-chloropropylamine hydrochloride was added and the mixture was stirred at room temperature for 36 h. 150 mL of ethyl acetate was added and the mixture was washed with deionized water and saturated sodium chloride solution. The organic layer was dried with anhydrous magnesium sulfate, filtered, and the filtrate was distilled under reduced pressure to remove ethyl acetate.

[0071] V3. Take 4.5 g of IPTS and add it to 45 mL of toluene and mix well to obtain an IPTS solution. In an 80°C water bath, add the product obtained in step V2 and 36 mg of dibutyltin dilaurate (DBTDL) to 36 mL of toluene and mix well. Add the mixture dropwise to the IPTS solution within 30 min and keep it at 80°C for 6 h. Wash the reaction solution with deionized water and remove the solvent by vacuum distillation of the organic layer.

[0072] V4. Mix 160 mL of anhydrous ethanol with 14 mL of concentrated ammonia to obtain solution A. Dissolve 20 g of TEOS in 80 mL of anhydrous ethanol to obtain solution B. Add solution B dropwise to solution A and react at 25 °C for 6 h. Add the product obtained in step V3 and continue the reaction for 18 h. Centrifuge at 8000 rpm for 8 min. Wash the precipitate with toluene, water, and ethanol, and dry under vacuum to obtain cashew phenol-SiO2.

[0073] This embodiment also provides a method for preparing the heat-resistant calcium-zinc stabilizer for PVC, including the following steps: 4 g of modified calcium salt, 1 g of modified zinc salt, 1 g of cashew phenol-SiO2 and 0.5 g of hydrotalcite are mixed at 800 r / min for 10 min; 0.2 g of pentaerythritol and 0.8 g of β-diketone are added and mixed at 600 r / min for 10 min; 0.5 g of antioxidant 1010 is added and mixed at 400 r / min for 5 min to obtain the heat-resistant calcium-zinc stabilizer for PVC.

[0074] Example 3: A heat-resistant calcium-zinc stabilizer for PVC, the raw materials for which are prepared include the following components in parts by weight: 5 parts modified calcium salt, 1.3 parts modified zinc salt, 1.2 parts cashew phenol-SiO2, 0.6 parts hydrotalcite, 0.25 parts pentaerythritol, 1 part β-diketone, and 0.6 parts antioxidant 1010.

[0075] The raw materials for preparing modified calcium salts include the following components in parts by weight: 10 parts methyl eugenol, 2.5 parts hexachlorocyclotriphosphazene (HCCP), and 5 parts calcium chloride.

[0076] The preparation method of modified calcium salt includes the following steps:

[0077] L1. Add 10 g of methyl eugenol to 100 mL of tetrahydrofuran (THF) and mix well to obtain a mixture. Dissolve 2.5 g of HCCP in 50 mL of THF, add 12.5 g of potassium carbonate, and add the mixture dropwise over 1 h. After the addition is complete, stir at 70 °C and 700 rpm and reflux for 12 h. Cool to room temperature, remove the solvent by rotary evaporation, wash with ethanol and deionized water, and dry under vacuum.

[0078] L2. Prepare an aqueous solution of 1.8 mmol / mL NaOH with 3.6 g of NaOH. Add the product obtained in step L1 to 15 times its weight volume of THF and add it dropwise to the NaOH aqueous solution over 1 h. After the addition is complete, reflux and stir at 70 °C for 1.5 h. Remove the solvent by rotary evaporation, add 10 times its weight volume of deionized water, adjust the pH to 2 with 1 mol / L hydrochloric acid, stir for 9 h, centrifuge at 8000 rpm for 12 min, wash the precipitate with distilled water and ethanol, and dry it.

[0079] L3. Prepare an aqueous solution of 0.1 g / mL calcium chloride with 5 g of calcium chloride. Add the product obtained in step L2 and 3.75 g of sodium bicarbonate to 187.5 mL of deionized water and react at 65 °C for 2 h. Add the calcium chloride aqueous solution dropwise. After the addition is complete, react at 70 °C for 3 h. Centrifuge at 8000 rpm for 12 min, wash with deionized water and ethanol, and vacuum dry to obtain the modified calcium salt.

[0080] The preparation method of modified zinc salt is the same as that of modified calcium salt, except that the raw material calcium chloride is replaced with 12 g of zinc sulfate heptahydrate.

[0081] The raw materials for preparing cashew phenol-SiO2 include the following components in parts by weight: 2,2'-(1,2-ethylenedioxydioxo)diethylthiol (DODT) 2.5 parts, cashew phenol 8.5 parts, 3-chloropropylamine hydrochloride 4 parts, 3-isocyanate-propyltrimethoxysilane (IPTS) 5.5 parts, and tetraethyl orthosilicate (TEOS) 25 parts.

[0082] The preparation method of cashew phenol-SiO2 includes the following steps:

[0083] V1. Add 2.5 g of DODT to 10 mL of ethyl acetate, stir and dissolve under a nitrogen atmosphere, heat to 70 °C to obtain DODT solution, dissolve 8.5 g of cashew phenol and 56 mg of azobisisobutyronitrile (AIBN) in 85 mL of ethyl acetate, add dropwise to DODT solution, react at 70 °C for 24 h, remove solvent by rotary evaporation, wash with anhydrous ethanol and dry.

[0084] V2. The product obtained in step V1 and 1.8 g of sodium hydroxide were added to 160 mL of N,N-dimethylformamide (DMF) and mixed well. Nitrogen gas was introduced for 10 min and stirred for 1 h. 4 g of 3-chloropropylamine hydrochloride was added and the mixture was stirred at room temperature for 36 h. 160 mL of ethyl acetate was added and the mixture was washed with deionized water and saturated sodium chloride solution. The organic layer was dried with anhydrous magnesium sulfate, filtered, and the filtrate was distilled under reduced pressure to remove ethyl acetate.

[0085] V3. Take 5.5 g of IPTS and add it to 55 mL of toluene and mix well to obtain an IPTS solution. In an 80°C water bath, add the product obtained in step V2 and 49.5 mg of dibutyltin dilaurate (DBTDL) to 49.5 mL of toluene and mix well. Add the mixture dropwise to the IPTS solution within 30 min and keep it at 80°C for 6 h. Wash the reaction solution with deionized water and remove the solvent by vacuum distillation of the organic layer.

[0086] V4. Mix 200 mL of anhydrous ethanol with 17.5 mL of concentrated ammonia to obtain solution A. Dissolve 25 g of TEOS in 100 mL of anhydrous ethanol to obtain solution B. Add solution B dropwise to solution A and react at 25 °C for 6 h. Add the product obtained in step V3 and continue the reaction for 18 h. Centrifuge at 8000 rpm for 10 min. Wash the precipitate with toluene, water, and ethanol, and dry under vacuum to obtain cashew phenol-SiO2.

[0087] This embodiment also provides a method for preparing the heat-resistant calcium-zinc stabilizer for PVC, comprising the following steps: mixing 5 g of modified calcium salt, 1.3 g of modified zinc salt, 1.2 g of cashew phenol-SiO2 and 0.6 g of hydrotalcite at 1000 r / min for 12 min, adding 0.25 g of pentaerythritol and 1 g of β-diketone, mixing at 700 r / min for 12 min, adding 0.6 g of antioxidant 1010, and mixing at 500 r / min for 7 min to obtain the heat-resistant calcium-zinc stabilizer for PVC.

[0088] The only difference between Comparative Example 1 and Example 1 is that calcium stearate is used instead of the modified calcium salt.

[0089] The only difference between Comparative Example 2 and Example 1 is that zinc stearate is used instead of the modified zinc salt.

[0090] The only difference between Comparative Example 3 and Example 1 is that steps V1-V3 are not performed. In step V4, solution B is added dropwise to solution A, reacted at 25°C for 24 h, centrifuged at 8000 rpm for 12 min, the precipitate is washed with toluene, water and ethanol, and dried under vacuum. The obtained product is used to replace cashew phenol-SiO2, that is, unmodified SiO2 is used to replace cashew phenol-SiO2.

[0091] Experimental Example 1: 3 g of the calcium-zinc stabilizer prepared in Examples 1-3 and Comparative Examples 1-3 was added to 100 g of PVC powder, along with 50 g of dioctyl phthalate. The mixture was high-speed mixed for 5 min, then kneaded on a two-roll mill at 180°C for 5 min. The mixture was rolled into a 1 mm thick sheet and cut into 2 cm × 2 cm PVC sheets. The resulting PVC sheets were placed in an oven at 180±1°C for static thermal aging tests. The time it took for the samples to turn black was observed to evaluate their thermal stability. The results are as follows: Figure 1 As shown.

[0092] Figure 1 The results showed that the blackening time of the samples in Examples 1-3 was significantly longer than that in Comparative Examples 1-3, and Examples 1-3 had better long-term thermal stability. This indicates that the modified calcium salt, modified zinc salt and cashew phenol-SiO2 prepared in this invention have a synergistic effect and can effectively improve the thermal stability of PVC.

[0093] Experimental Example 2: PVC sheets were prepared according to the method of Experimental Example 1. The Congo red stabilization time of Examples 1-3 and Comparative Examples 1-3 was determined according to the method of GB / T 2917.1-2002. The results are as follows: Figure 2 As shown.

[0094] Figure 2 The results showed that the time for the Congo red test paper in Examples 1-3 and Comparative Examples 1-3 to turn blue was significantly longer than that in Comparative Examples 1-3, indicating that the modified calcium salt, modified zinc salt and cashew phenol-SiO2 prepared in this invention have a synergistic effect and can effectively provide long-term heat resistance stability for PVC.

[0095] Experimental Example 3: The tensile strength and elongation at break of PVC samples were tested according to GB / T1040.1-2006 "Determination of Tensile Properties of Plastics Part 1: General Rules". After heat aging at 180℃ for 120 min, the tensile strength and elongation at break were tested again. The retention rates of tensile strength and elongation at break of the PVC samples before and after heating were calculated. The results are as follows: Figure 3 As shown.

[0096] Figure 3 The results showed that the PVC in Examples 1-3 had better long-term stability than that in Comparative Example 1, and had a better retention rate of mechanical properties of PVC resin. This indicates that the calcium-zinc stabilizer prepared by the present invention has excellent thermal stability and can improve the problem of mechanical property degradation during thermal aging of products.

[0097] Experimental Example 3: Unmodified SiO2 obtained from Comparative Example 3 was dispersed in anhydrous ethanol, dropped onto a copper grid, and allowed to dry naturally. The resulting scanning electron microscope (SEM) image is shown below. Figure 4 As shown in Figure a, the cashew phenol-SiO2 prepared in Example 1 was dispersed in anhydrous ethanol, dropped onto a copper grid, and allowed to dry naturally. The image was then observed using a scanning electron microscope (SEM). Figure 4 As shown in a.

[0098] Figure 4 The results showed that both unmodified SiO2 and cashew phenol-SiO2 were spherical particles with uniform particle size. The average particle size of cashew phenol-SiO2 was larger than that of unmodified SiO2, and a light-colored halo was observed on its surface, indicating the successful preparation of cashew phenol-SiO2.

[0099] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A heat-resistant calcium-zinc stabilizer for PVC, characterized in that, The raw materials for preparation include the following components in parts by weight: 4-6 parts modified calcium salt, 1-1.5 parts modified zinc salt, 1-1.5 parts cashew phenol-SiO2, 0.5-1 parts hydrotalcite, 0.2-0.3 parts pentaerythritol, 0.8-1.2 parts β-diketone, and 0.5-0.7 parts antioxidant; The method for preparing the modified calcium salt includes the following steps: L1. Add 8-12 parts by weight of methyl eugenol to THF to obtain a mixture. Dissolve 2-3 parts of hexachlorocyclotriphosphazene in THF, add potassium carbonate, add the mixture dropwise, reflux, rotary evaporate, wash, and dry. L2. Add the product obtained in step L1 to THF, add dropwise to NaOH aqueous solution, reflux, evaporate by rotary evaporation, add water, adjust pH, stir, centrifuge, wash, and dry. L3. Prepare an aqueous solution of 4-6 parts of calcium chloride, add the product obtained in step L2 and sodium bicarbonate to water, react, add calcium chloride aqueous solution dropwise, react, centrifuge, wash, dry, and obtain modified calcium salt; The method for preparing the cashew phenol-SiO2 includes the following steps: V1. Dissolve 2-3 parts of 2,2'-(1,2-ethylenedioxy)diethanethiol in ethyl acetate, heat to obtain a 2,2'-(1,2-ethylenedioxy)diethanethiol solution, dissolve 7-10 parts of cashew nut shell powder and azobisisobutyronitrile in ethyl acetate, add dropwise to the 2,2'-(1,2-ethylenedioxy)diethanethiol solution, react, rotary evaporate, wash, and dry; V2. Add the product obtained in step V1 and sodium hydroxide to DMF, mix well, stir, add 3-4.5 parts of 3-chloropropylamine hydrochloride, react, add ethyl acetate, wash, dry, and distill under reduced pressure; V3. Take 4.5-6.8 parts of 3-isocyanate-propyltrimethoxysilane and add it to toluene and mix well to obtain a 3-isocyanate-propyltrimethoxysilane solution. Add the product obtained in step V2 and dibutyltin dilaurate to toluene and add it dropwise to the 3-isocyanate-propyltrimethoxysilane solution. React, wash, and distill under reduced pressure. V4. Mix anhydrous ethanol and concentrated ammonia to obtain solution A. Dissolve 20-30 parts of tetraethyl orthosilicate in anhydrous ethanol to obtain solution B. Add solution B dropwise to solution A and react. Add the product obtained in step V3 and continue the reaction. Centrifuge, wash, and dry to obtain cashew phenol-SiO2. The preparation method of the modified zinc salt is the same as that of the modified calcium salt, except that the raw material calcium chloride is replaced with 10-15 parts of zinc sulfate heptahydrate.

2. The heat-resistant calcium-zinc stabilizer for PVC according to claim 1, characterized in that, In step V1, the mass concentration of 2,2'-(1,2-ethylenedioxy)diethylthiol in ethyl acetate is 0.2-0.3 g / mL; the mass concentration of cashew phenol in ethyl acetate is 0.1 g / mL.

3. The heat-resistant calcium-zinc stabilizer for PVC according to claim 2, characterized in that, In step V2, the mass ratio of sodium hydroxide to 3-chloropropylamine hydrochloride is 1:2-2.5; the mass concentration of 3-chloropropylamine hydrochloride in DMF is 20-30 mg / mL; and the volume ratio of ethyl acetate to DMF is 1:

1.

4. The heat-resistant calcium-zinc stabilizer for PVC according to claim 3, characterized in that, In step V3, the mass concentration of 3-isocyanate-propyltrimethoxysilane in toluene is 0.1 g / mL; the mass concentration of dibutyltin dilaurate in toluene is 1 mg / mL.

5. A method for preparing a heat-resistant calcium-zinc stabilizer for PVC as described in any one of claims 1-4, characterized in that, Includes the following steps: Modified calcium salt, modified zinc salt, cashew phenol-SiO2 and hydrotalcite are mixed, pentaerythritol and β-diketone are added, and then an antioxidant is added and mixed to obtain a heat-resistant calcium-zinc stabilizer for PVC.

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