A high-gloss and oil-resistant refrigerator liner material and its preparation method

Abstract

The invention discloses a high-gloss oil-resistant refrigerator liner material and a preparation method thereof, belonging to the technical field of modified plastics. The material comprises the following raw materials in parts by weight: 5-20 parts of homopolymer PP, 30-60 parts of GPPS, 10-30 parts of HIPS, 3-5 parts of maleic anhydride-grafted styrene-ethylene-butylene-styrene blocks, 10-20 parts of modified silica, 1 part of a migration-resistant antioxidant, and 1 part of a lubricant. The raw materials are mixed and extruded into granules. In the invention, the modified silica and the migration-resistant antioxidant are added to the refrigerator liner material. The former forms a rough structure on the surface of the composite material, thereby improving the water resistance, oil resistance, and impact resistance of the composite material. The latter has the advantages of migration resistance and precipitation resistance, thereby endowing the refrigerator liner material with excellent oxidation resistance. Therefore, the refrigerator liner material of the invention not only has high gloss, but also has good mechanical properties and strong oxidation resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of modified plastics, and particularly relates to a high-gloss and oil-resistant refrigerator liner material and a preparation method thereof. Background Art

[0002] Polystyrene (PS) is a colorless and transparent thermoplastic. One of the obvious disadvantages of polystyrene is its poor solvent resistance. It can be dissolved by a variety of organic solvents, corroded by strong acids and alkalis, and is not resistant to grease.

[0003] Most existing refrigerator liners are made of polystyrene as the main material, compounded with other materials and additives, and obtained through extrusion and vacuum molding. They play the role of thermal insulation and isolation, and are required to have high solvent resistance, low temperature resistance and impact resistance. However, polystyrene itself has poor solvent resistance and is easily contaminated, which causes it to age under heat, oxygen and atmospheric conditions, resulting in the breakage of macromolecular chains and color development. After long-term use, the refrigerator liner will become yellow and brittle, affecting its performance and aesthetics. Therefore, it is necessary to develop a high-gloss and oil-resistant refrigerator liner material with better performance. Summary of the Invention

[0004] The object of the present invention is to provide a high-gloss and oil-resistant refrigerator liner material and a preparation method thereof, so as to solve the problems in the background technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A high-gloss and oil-resistant refrigerator liner material comprises the following raw materials in parts by weight: 5-20 parts of homopolypropylene (homo-PP), 30-60 parts of general-purpose polystyrene (GPPS), 10-30 parts of high-impact polystyrene (HIPS), 3-5 parts of maleic anhydride-grafted styrene-ethylene-butylene-styrene block copolymer, 10-20 parts of modified silica, 1 part of a migration-resistant antioxidant, and 1 part of a lubricant.

[0007] The high-gloss oil-resistant refrigerator liner material is made by the following steps:

[0008] Homopolymer polypropylene, general-grade polystyrene, high-impact polystyrene, maleic anhydride grafted styrene-ethylene-butylene-styrene block, modified silica, migration-resistant antioxidant and lubricant are added to a high-speed mixer, stirred and mixed for 10-30 minutes, and then transferred to a twin-screw extruder for extrusion and granulation to obtain a high-gloss and oil-resistant refrigerator liner material.

[0009] Furthermore, during the extrusion process, the temperature is controlled at 180-240° C. and the screw speed is controlled at 180-300 r / min.

[0010] Furthermore, the modified silica preparation steps are as follows:

[0011] Step S1, mixing nano-silica, coupling agent KH-550, deionized water and anhydrous ethanol, ultrasonically dispersing for 0.5 h, adding trimethylchlorosilane dropwise, and reacting at 50-55° C. for 5-6 h. After the reaction, filtering, washing the filter cake with anhydrous ethanol and deionized water 3-5 times, and drying to obtain amino-terminated hyperbranched polysiloxane grafted nano-silica, i.e., amino-silica;

[0012] Step S2, adding amino silica to anhydrous ethanol, ultrasonically dispersing, and then adding dibutyltin dilaurate dropwise, and then adding allyl isothiocyanate dropwise while stirring. After the addition is completed, the temperature is raised to 50° C. and stirred for reaction for 4-5 hours, and then the temperature is lowered to room temperature and the reaction is continued for 48 hours. After the reaction is completed, the mixture is filtered with suction, and the filter cake is dried to obtain thiourea silica;

[0013] Step S3: thiourea-based silica, perfluoroalkylthiol, benzoin dimethyl ether and THF are mixed, dissolved and placed under a 300W ultraviolet lamp for reaction for 30-50 minutes. After the reaction is completed, THF is removed by rotary evaporation to obtain modified silica.

[0014] The invention uses nano-silica as a base material and utilizes its good light transmittance to enhance and toughen the resin raw material without affecting its high light properties. First, a hyperbranched polysiloxane with terminal amino groups is introduced into the surface of the nano-silica in the form of chemical bonding through an in-situ polymerization reaction. On the one hand, the low viscosity and easy solubility of the hyperbranched polymer are utilized to improve the dispersibility of the nano-silica in the resin matrix. On the other hand, the active -NH2 of the nano-silica is utilized to react with the -NCS of allyl isothiocyanate to form a thiourea structure and introduce an unsaturated double bond, laying the foundation for the next reaction. Finally, the unsaturated double bond is utilized to react with the mercapto group of perfluoroalkyl mercaptan under the action of a photoinitiator to generate an addition reaction, thereby introducing a fluorocarbon long chain onto the surface of the thiourea-based silica to obtain the modified silica.

[0015] Furthermore, in step S1, the mass ratio of nano-silica, deionized water and anhydrous ethanol is 10:20-30:40-50, the amount of coupling agent KH-550 is 4-5% of the mass of nano-silica, and the molar ratio of KH-550 and trimethylchlorosilane is 1:1-1.5.

[0016] Furthermore, in step S2, the usage ratio of amino silica, anhydrous ethanol, dibutyltin dilaurate and allyl isothiocyanate is 10 g: 80-100 mL: 0.06-0.07 g: 7.5-8.1 g.

[0017] Furthermore, in step S3, the usage ratio of thiourea-based silica, perfluoroalkylthiol, benzoin dimethyl ether and THF is 10 g: 0.8-2.1 g: 0.1 g: 100 mL.

[0018] Furthermore, the steps for preparing the migration-resistant antioxidant are as follows:

[0019] Step S21, adding isophorone diisocyanate, tetramethylpiperidinol and DMF into a flask, adding dibutyltin dilaurate dropwise at 35° C. under nitrogen protection, stirring and reacting for 1 hour after the addition is completed, and removing DMF by reduced pressure distillation to obtain an intermediate product, wherein the mass ratio of isophorone diisocyanate, tetramethylpiperidinol, DMF and dibutyltin dilaurate is 46:15.7:100-150:0.1;

[0020] Step S22, adding antioxidant 1010 to ethyl acetate, heating to 80° C. under nitrogen protection, adding the intermediate product and dibutyltin dilaurate, and keeping the temperature to react for 14-16 hours to obtain a migration-resistant antioxidant, wherein the mass ratio of antioxidant 1010, ethyl acetate, intermediate product and dibutyltin dilaurate is 60:120:64-69:0.1.

[0021] The present invention uses isophorone diisocyanate and tetramethylpiperidinol as raw materials, and obtains an intermediate product through the reaction between -OH and -NCO groups. It can be seen that the intermediate product contains a hindered amine structure and an -NCO group. Then, the -NCO group is reacted with the phenolic hydroxyl group of antioxidant 1010 to obtain a migration-resistant antioxidant. It can be seen that the migration-resistant antioxidant not only has a large molecular weight but also contains hindered phenol and hindered amine structures.

[0022] Furthermore, the lubricant is one or a mixture of silicone oil, white mineral oil, fatty acid amide, stearate, paraffin, polyethylene wax or ethylene bisstearamide.

[0023] Beneficial effects of the present invention:

[0024] The present invention adds modified silica to a resin base material, and the modified silica forms a rough structure on the surface of the composite material. A large amount of air exists in the tiny gaps of the rough structure. According to the Cassie-Baxter theory, when a liquid droplet falls on the material surface, the liquid cannot completely penetrate the surface it contacts due to the obstruction of the air in the rough structure, resulting in a large contact angle, thereby achieving water resistance and oil resistance of the composite material. Compared with the prior art that directly adds a perfluoroalkyl acrylic olefin material as an oil-resistant modifier, the fluorocarbon long chain in the present invention is grafted to the silica surface through a chemical bond, has high migration resistance and precipitation resistance, and does not pose a safety hazard when used as a refrigerator liner material. In addition, the flexible Si-O-Si chain segments in the nano-silica and hyperbranched polysiloxane and the cavity structure of the highly branched molecules can absorb impact energy, thereby improving the impact resistance of the composite material. The thiourea structure can synergistically act with the migration-resistant antioxidant to improve the antioxidant performance of the composite material.

[0025] Compared with existing antioxidants, the migration-resistant antioxidant of the present invention has a large molecular weight and has the advantages of migration resistance and precipitation resistance; and contains hindered phenol and hindered amine structures, and has high antioxidant performance;

[0026] In summary, the refrigerator liner material of the present invention not only has high light properties, but also has good mechanical properties and strong oxidation resistance. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] Example 1

[0029] A modified silica, the preparation steps are as follows:

[0030] Step S1, 10g of nano-silica, coupling agent KH-550, 20g of deionized water and 40g of anhydrous ethanol were mixed, ultrasonically dispersed for 0.5h, trimethylchlorosilane was added dropwise, and after the addition was completed, the temperature was 50°C and the reaction was carried out for 5h. After the reaction was completed, the filter cake was filtered and washed three times with anhydrous ethanol and deionized water, and dried to obtain amino-silica. The amount of coupling agent KH-550 was 4% of the mass of the nano-silica, and the molar ratio of KH-550 to trimethylchlorosilane was 1:1;

[0031] Step S2, adding 10 g of amino silica to 80 mL of anhydrous ethanol, adding 0.06 g of dibutyltin dilaurate dropwise after ultrasonic dispersion, and then adding 7.5 g of allyl isothiocyanate dropwise while stirring. After the addition is completed, the temperature is raised to 50° C. and stirred for reaction for 4 h, then cooled to room temperature and continued to react for 48 h. After the reaction is completed, the mixture is filtered with suction and the filter cake is dried to obtain thiourea silica;

[0032] Step S3: 10 g of thiourea-based silica, 0.8 g of perfluoroalkylthiol, 0.1 g of benzoin dimethyl ether and 100 mL of THF were mixed, dissolved, and placed under a 300 W ultraviolet lamp for reaction for 30 min. After the reaction was completed, THF was removed by rotary evaporation to obtain modified silica.

[0033] Example 2

[0034] A modified silicon dioxide, the preparation steps are as follows:

[0035] Step S1, 10g of nano-silica, coupling agent KH-550, 30g of deionized water and 50g of anhydrous ethanol were mixed, ultrasonically dispersed for 0.5h, trimethylchlorosilane was added dropwise, and after the addition was completed, the temperature was 55°C, and the reaction was carried out for 5-6h. After the reaction was completed, the filter cake was filtered, and the filter cake was washed 5 times with anhydrous ethanol and deionized water, and dried to obtain amino-silica. The amount of coupling agent KH-550 was 5% of the mass of the nano-silica, and the molar ratio of KH-550 to trimethylchlorosilane was 1:1.5;

[0036] Step S2, adding 10 g of amino silica to 100 mL of anhydrous ethanol, adding 0.07 g of dibutyltin dilaurate dropwise after ultrasonic dispersion, and then adding 8.1 g of allyl isothiocyanate dropwise while stirring. After the addition is completed, the temperature is raised to 50° C. and stirred for reaction for 5 h, then cooled to room temperature and continued to react for 48 h. After the reaction is completed, the mixture is filtered with suction and the filter cake is dried to obtain thiourea silica;

[0037] Step S3: 10 g of thiourea-based silica, 2.1 g of perfluoroalkylthiol, 0.1 g of benzoin dimethyl ether and 100 mL of THF were mixed, dissolved, and placed under a 300 W ultraviolet lamp for reaction for 50 min. After the reaction was completed, THF was removed by rotary evaporation to obtain modified silica.

[0038] Comparative Example 1

[0039] This comparative example is the amino silica obtained in step S1 of Example 1.

[0040] Example 3

[0041] The steps for preparing a migration-resistant antioxidant are as follows:

[0042] Step S21, adding 46 g of isophorone diisocyanate, 15.7 g of tetramethylpiperidinol and 100 g of DMF into a flask, adding 0.1 g of dibutyltin dilaurate dropwise at 35° C. under nitrogen protection, stirring and reacting for 1 h. After the reaction, removing DMF by vacuum distillation to obtain an intermediate product;

[0043] Step S22: add 60 g of antioxidant 1010 to 120 g of ethyl acetate, raise the temperature to 80° C. under nitrogen protection, add 64 g of the intermediate product, add 0.1 g of dibutyltin dilaurate, and react at this temperature for 14 hours to obtain a migration-resistant antioxidant.

[0044] Example 4

[0045] The steps for preparing a migration-resistant antioxidant are as follows:

[0046] Step S21, adding 46 g of isophorone diisocyanate, 15.7 g of tetramethylpiperidinol and 150 g of DMF into a flask, adding 0.1 g of dibutyltin dilaurate dropwise at 35° C. under nitrogen protection, stirring and reacting for 1 h. After the reaction is completed, removing DMF by vacuum distillation to obtain an intermediate product;

[0047] Step S22: add 60 g of antioxidant 1010 to 120 g of ethyl acetate, raise the temperature to 80° C. under nitrogen protection, add 69 g of the intermediate product, add 0.1 g of dibutyltin dilaurate, and react at this temperature for 16 hours to obtain a migration-resistant antioxidant.

[0048] Comparative Example 2

[0049] This comparative example is antioxidant 1010.

[0050] Example 5

[0051] A high-gloss and oil-resistant refrigerator liner material comprises the following raw materials in parts by weight: 5 parts of homopolypropylene (homo-PP), 60 parts of general-purpose polystyrene (GPPS), 30 parts of high-impact polystyrene (HIPS), 5 parts of maleic anhydride-grafted styrene-ethylene-butylene-styrene block, 10 parts of the modified silica of Example 1, 1 part of the migration-resistant antioxidant of Example 3, and 1 part of a lubricant.

[0052] The high-gloss oil-resistant refrigerator liner material is made by the following steps:

[0053] Homopolymer polypropylene, general-grade polystyrene, high-impact polystyrene, maleic anhydride grafted styrene-ethylene-butylene-styrene block, modified silica, migration-resistant antioxidant and lubricant are added to a high-speed mixer, stirred and mixed for 10 minutes, and then transferred to a twin-screw extruder for extrusion and granulation to obtain a high-gloss and oil-resistant refrigerator liner material.

[0054] During the extrusion process, the temperature was controlled at 180-240° C., the screw speed was 180 r / min, and the lubricant was silicone oil.

[0055] Example 6

[0056] A high-gloss and oil-resistant refrigerator liner material comprises the following raw materials in parts by weight: 10 parts of homopolypropylene (homo-PP), 56 parts of general-purpose polystyrene (GPPS), 30 parts of high-impact polystyrene (HIPS), 4 parts of maleic anhydride-grafted styrene-ethylene-butylene-styrene block, 15 parts of the modified silica of Example 2, 1 part of the migration-resistant antioxidant of Example 3, and 1 part of a lubricant.

[0057] The high-gloss oil-resistant refrigerator liner material is made by the following steps:

[0058] Homopolymer polypropylene, general-grade polystyrene, high-impact polystyrene, maleic anhydride grafted styrene-ethylene-butylene-styrene block, modified silica, migration-resistant antioxidant and lubricant are added to a high-speed mixer, stirred and mixed for 20 minutes, and then transferred to a twin-screw extruder for extrusion and granulation to obtain a high-gloss and oil-resistant refrigerator liner material.

[0059] During the extrusion process, the temperature was controlled at 180-240° C., the screw speed was 200 r / min, and the lubricant was white mineral oil.

[0060] Example 7

[0061] A high-gloss and oil-resistant refrigerator liner material comprises the following raw materials in parts by weight: 20 parts of homopolypropylene (homo-PP), 50 parts of general-purpose polystyrene (GPPS), 25 parts of high-impact polystyrene (HIPS), 5 parts of maleic anhydride-grafted styrene-ethylene-butylene-styrene block, 20 parts of the modified silica of Example 2, 1 part of the migration-resistant antioxidant of Example 4, and 1 part of a lubricant.

[0062] The high-gloss oil-resistant refrigerator liner material is made by the following steps:

[0063] Homopolymer polypropylene, general-grade polystyrene, high-impact polystyrene, maleic anhydride grafted styrene-ethylene-butylene-styrene block, modified silica, migration-resistant antioxidant and lubricant are added to a high-speed mixer, stirred and mixed for 30 minutes, and then transferred to a twin-screw extruder for extrusion and granulation to obtain a high-gloss and oil-resistant refrigerator liner material.

[0064] During the extrusion process, the temperature is controlled at 180-240° C., the screw speed is 300 r / min, and the lubricant is fatty acid amide.

[0065] Comparative Example 3

[0066] Compared with Example 5, the modified silica in Example 5 was replaced by the substance in Comparative Example 1, and the remaining raw materials and preparation process were the same as in Example 5.

[0067] Comparative Example 4

[0068] Compared with Example 5, the migration-resistant antioxidant in Example 5 is replaced by the substance in Comparative Example 2, and the remaining raw materials and preparation process are the same as in Example 5.

[0069] The performance tests of the refrigerator liner materials prepared in Examples 5-7 and Comparative Examples 3-4 were conducted, and the test items and standards were as follows:

[0070] (1) Glossiness: tested in accordance with standard GB / T8807;

[0071] (2) Tensile strength: Tested in accordance with standard GB / T1040;

[0072] (3) Notched impact strength: tested in accordance with GB / T1843;

[0073] (IV) Oil resistance: Bend an American standard tensile specimen and fix it with a clamp (arc inner diameter 20 cm). The distance between the clamps is 5 cm shorter than the specimen to obtain the specimen to be tested. Cover the surface of the specimen with medical gauze and apply commercially available soybean blend oil. Leave it for 8 hours. Wipe the blend oil on the specimen and dry it. Leave it for another 24 hours. Observe the surface for cracks and test the elongation at break. For the elongation at break before the test (no bending and no oiling), calculate ESCR = (elongation at break after the test - elongation at break before the test) / elongation at break before the test (refer to GB / T1040). The larger the ESCR, the better the oil resistance.

[0074] (5) Oxidation resistance: Place the American standard tensile specimens in a 401A thermal aging test chamber and simulate thermal oxidation aging at 80°C for 12 hours. The aged material specimens are subjected to a tensile strength test according to the same test standard and the tensile property retention rate is calculated;

[0075] The results are shown in Table 1:

[0076] Table 1

[0077]

[0078]

[0079] It can be seen from Table 1 that, compared with Comparative Examples 3-4, the refrigerator liner materials prepared in Examples 5-7 not only have high gloss and good mechanical properties, but also have excellent oil resistance, solvent resistance, and oxidation resistance, and are suitable for preparing refrigerator liner.

[0080] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A high-gloss and oil-resistant refrigerator liner material, characterized in that: The invention comprises the following raw materials in parts by weight: 5-20 parts of homopolypropylene, 30-60 parts of general-purpose polystyrene, 10-30 parts of high-impact polystyrene, 3-5 parts of maleic anhydride grafted styrene-ethylene-butylene-styrene block, 10-20 parts of modified silica, 1 part of migration-resistant antioxidant, and 1 part of lubricant; The steps for preparing modified silica are as follows: Thiourea-based silica, perfluoroalkylthiol, benzoin dimethyl ether and THF were mixed and reacted under a 300W ultraviolet lamp for 30-50 minutes to obtain modified silica; The preparation steps of thiourea-based silica are as follows: Add aminated silica to anhydrous ethanol, ultrasonically disperse, then dropwise add dibutyltin dilaurate, and dropwise add allyl isothiocyanate while stirring. After the addition is complete, heat to 50°C and stir to react for 4-5 hours, then cool to room temperature and continue to react for 48 hours to obtain thiourea silica; The preparation steps of amination silica are as follows: Nano-silica, coupling agent KH-550, deionized water and anhydrous ethanol were mixed and ultrasonically dispersed for 0.5 h. Trimethylchlorosilane was added dropwise. After the addition was completed, the mixture was reacted at 50-55° C. for 5-6 h to obtain amino-silica.

2. The high-gloss and oil-resistant refrigerator liner material according to claim 1, characterized in that: The usage ratio of thiourea-based silica, perfluoroalkylthiol, benzoin dimethyl ether and THF is 10 g: 0.8-2.1 g: 0.1 g: 100 mL.

3. The high-gloss and oil-resistant refrigerator liner material according to claim 1, characterized in that: The usage ratio of amino silicon dioxide, anhydrous ethanol, dibutyltin dilaurate and allyl isothiocyanate is 10g:80-100mL:0.06-0.07g:7.5-8.1g.

4. The high-gloss and oil-resistant refrigerator liner material according to claim 1, characterized in that: The mass ratio of nano-silica, deionized water and anhydrous ethanol is 10:20-30:40-50, the amount of coupling agent KH-550 is 4-5% of the mass of nano-silica, and the molar ratio of KH-550 and trimethylchlorosilane is 1:1-1.

5.

5. The high-gloss and oil-resistant refrigerator liner material according to claim 1, characterized in that: The steps for preparing the migration-resistant antioxidant are as follows: Step S21, adding isophorone diisocyanate, tetramethylpiperidinol and DMF into a flask, adding dibutyltin dilaurate dropwise at 35° C. under nitrogen protection, stirring and reacting for 1 hour, and removing DMF by vacuum distillation after the reaction is completed to obtain an intermediate product; Step S22: adding the antioxidant 1010 to ethyl acetate, heating to 80° C. under nitrogen protection, adding the intermediate product and dibutyltin dilaurate, and reacting at this temperature for 14-16 hours to obtain a migration-resistant antioxidant.

6. The high-gloss and oil-resistant refrigerator liner material according to claim 5, characterized in that: The mass ratio of isophorone diisocyanate, tetramethylpiperidinol, DMF and dibutyltin dilaurate is 46:15.7:100-150:0.

1.

7. The high-gloss and oil-resistant refrigerator liner material according to claim 5, characterized in that: The mass ratio of antioxidant 1010, ethyl acetate, intermediate product and dibutyltin dilaurate is 60:120:64-69:0.

1.

8. The method for preparing a high-gloss and oil-resistant refrigerator liner material according to claim 1, characterized in that: The following steps are involved: Homopolymer polypropylene, general-grade polystyrene, high-impact polystyrene, maleic anhydride grafted styrene-ethylene-butylene-styrene block, modified silica, migration-resistant antioxidant and lubricant are stirred and mixed, and transferred to a twin-screw extruder for extrusion and granulation to obtain a high-gloss and oil-resistant refrigerator liner material.

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