A PP composite material for refrigerator liner and preparation method thereof

Abstract

The present invention discloses a PP composite material for refrigerator liner and a preparation method thereof, which comprises 30-50 parts of PP resin, 10-50 parts of PS resin, 5-15 parts of reinforcing agent, 2-20 parts of compatibilizer, and 0.1-5 parts of other auxiliary agents according to the weight percentage. Compared with the prior art, the PP material prepared by the present invention has excellent performance in tensile strength, impact strength, elongation at break, resistance to foaming agent corrosion, aging resistance, as well as tensile strength and elongation at break after oil corrosion.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to a PP composite material for a refrigerator liner and a preparation method thereof. Background Art

[0002] Currently, most refrigerator liners are made of non-crystalline HIPS through extrusion and vacuum forming. Since foam material is usually used as an insulation layer between the refrigerator liners and the external metal shell, HIPS has poor resistance to edible oil and foaming agent corrosion and is easily aged. The "linen crack" phenomenon that causes the refrigerator liners to crack occurs frequently, becoming a pain point that plagues the refrigerator industry.

[0003] Polypropylene material has excellent electrical insulation properties and chemical stability, hardly absorbs water, and has no reaction to most chemicals, making it very suitable for use in refrigerator liners. However, polypropylene does not combine firmly with conventional fillers, resulting in poor mechanical, corrosion resistance, and aging resistance properties. Summary of the invention

[0004] In order to solve the problems mentioned in the above background technology, the present invention provides a PP composite material for a refrigerator liner and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a PP composite material for a refrigerator liner, which comprises, by weight, 30-50 parts of PP resin, 10-50 parts of PS resin, 5-15 parts of reinforcing agent, 2-20 parts of compatibilizer, and 0.1-5 parts of other additives.

[0007] Preferably, the PP resin is any one or both of homopolypropylene and copolymer polypropylene.

[0008] Preferably, the PS resin is any one or both of polystyrene and high impact polystyrene.

[0009] Preferably, the preparation method of the enhancer is as follows:

[0010] The surfaces of talcum powder and basic magnesium sulfate whiskers are modified by epoxy silane coupling agent to obtain epoxy-modified composite powder;

[0011] Polyethyleneimine modified with di-tert-butyl chloromethyl phosphate is reacted to obtain phosphate-modified polyethyleneimine;

[0012] The reinforcing agent is obtained by reacting phosphate-modified polyethyleneimine with the modified composite powder.

[0013] Preferably, the mass ratio of the epoxy silane coupling agent, talcum powder and basic magnesium sulfate whisker is (0.1-0.5):(1-5):(1-5).

[0014] Preferably, the mass ratio of polyethyleneimine to di-tert-butyl chloromethyl phosphate is 1:(1-3).

[0015] Preferably, the mass ratio of the phosphate-modified polyethyleneimine to the modified composite powder is (0.5-2):1.

[0016] Preferably, the compatibilizer is hydrogenated styrene-butadiene block copolymer (SEBS).

[0017] Preferably, the other additives include any one or more of an initiator, an antioxidant, a lubricant, and titanium dioxide;

[0018] Wherein, the initiator is di-tert-butyl peroxide (DTBT);

[0019] The antioxidant is any one or more of antioxidant 168, antioxidant 1010, and antioxidant 1076;

[0020] The lubricant is vinyl bisstearamide (EBS).

[0021] The present invention also provides a method for preparing a PP composite material, comprising the following steps:

[0022] S1. Mix PP resin, PS resin, reinforcing agent, compatibilizer and other additives to obtain a mixture;

[0023] S2. The mixture was added to a twin-screw extruder, and the mixture was melt-extruded and granulated to obtain the PP composite material;

[0024] Among them, the mixing speed in S1 is 400-500rpm, and the mixing time is 5-30min;

[0025] The temperatures of each section of the twin-screw extruder in S2 are 170-180°C, 180-190°C, 190-200°C, 200-210°C, 210-220°C, and the screw speed is 300-600rpm.

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

[0027] 1. The PP material prepared by the present invention has excellent performance in tensile strength, impact strength, elongation at break, resistance to foaming agent corrosion, aging resistance, as well as tensile strength and elongation at break after oil corrosion.

[0028] 2. First, talcum powder and basic magnesium sulfate whiskers are modified by an epoxy silane coupling agent to introduce epoxy groups on their surfaces to obtain epoxy-modified composite powders. Secondly, under alkaline conditions, chlorine in di-tert-butyl chloromethyl phosphate reacts with active hydrogen in polyethyleneimine to obtain phosphate-modified polyethyleneimine. Finally, the epoxy-modified composite powders are subjected to a ring-opening reaction with the remaining active hydrogen in the phosphate-modified polyethyleneimine to obtain the reinforcing agent.

[0029] 3. By introducing epoxy groups on the surface of talc powder and basic magnesium sulfate whiskers, it is helpful to disperse the composite powder in the PP composite material. The further introduction of phosphate-modified polyethyleneimine and the synergistic effect of nitrogen and phosphorus not only help the dispersion of the powder and improve the mechanical properties, but also improve the overall corrosion resistance, aging resistance, flame retardancy, high temperature resistance and other properties of the PP composite material. DETAILED DESCRIPTION

[0030] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0031] Among them, some raw materials come from the following sources:

[0032] Homopolymer polypropylene, T30S, Dushanzi Petrochemical;

[0033] Copolymer polypropylene, K8009, Yanshan Petrochemical;

[0034] Polystyrene, 158K, BASF-YPC;

[0035] High impact polystyrene, 2710, BASF-YP;

[0036] Hydrogenated styrene-butadiene block copolymer (SEBS): YH501, Baling Petrochemical;

[0037] Titanium dioxide, Longbai Group Co., Ltd., whiteness 97;

[0038] Antioxidant 168, Antioxidant 1010, Antioxidant 1076, BASF;

[0039] Ethylene bisstearamide (EBS), Indonesia EBS B50;

[0040] Polyethylenimine, Aladdin, E670260;

[0041] Talc powder, Guangxi Longguang Talc Development Co., Ltd., 1500 mesh;

[0042] Basic magnesium sulfate whiskers, Shanghai Kaishefeng Industrial Co., Ltd., 1250 mesh.

[0043] Preparation Example 1

[0044] 100 g of talcum powder and 50 g of basic magnesium sulfate whisker were added to 2 L of 70% ethanol aqueous solution, stirred and heated to 50° C., 15 g of 3-glycidyloxypropyltriethoxysilane was added, stirred and reacted at 60° C. for 2 h, and dried to obtain epoxy-modified composite powder;

[0045] Under nitrogen protection, 258g of di-tert-butyl chloromethyl phosphate, 3L of DMF (N,N-dimethylformamide), and 150g of triethylamine were mixed and stirred evenly, 100g of 10% NaOH solution was added, and 100g of polyethyleneimine was added. The mixture was reacted at 85°C for 2h, the solvent was removed, the mixture was dissolved in dichloromethane, washed with saturated brine, and dried to obtain phosphate-modified polyethyleneimine.

[0046] 100 g of epoxy-modified composite powder was dispersed in 2 L of anhydrous ethanol, 80 g of phosphate-modified polyethyleneimine was added, and the mixture was reacted at 60° C. for 2 h, and the ethanol was removed to obtain the reinforcing agent.

[0047] Preparation Example 2

[0048] The difference between this preparation example and preparation example 1 is that 75 g of talc and 75 g of basic magnesium sulfate whiskers are added to 2 L of 70% by mass ethanol aqueous solution;

[0049] The rest is exactly the same as Preparation Example 1.

[0050] Preparation Example 3

[0051] The difference between this preparation example and preparation example 1 is that 112.5 g of talc and 37.5 g of basic magnesium sulfate whiskers are added to 2 L of 70% by mass ethanol aqueous solution;

[0052] The rest is exactly the same as Preparation Example 1.

[0053] Preparation Example 4

[0054] The difference between this preparation example and preparation example 1 is that 0 g of talcum powder and 150 g of basic magnesium sulfate whiskers are added to 2 L of 70% by mass ethanol aqueous solution;

[0055] The rest is exactly the same as Preparation Example 1.

[0056] Preparation Example 5

[0057] The difference between this preparation example and preparation example 1 is that 150 g of talc and 0 g of basic magnesium sulfate whisker are added to 2 L of 70% by mass ethanol aqueous solution;

[0058] The rest is exactly the same as Preparation Example 1. Example 1

[0059] A PP composite material for a refrigerator liner comprises, by weight, 40 parts of homopolypropylene, 30 parts of polystyrene, 10 parts of a reinforcing agent (obtained in Preparation Example 1), 10 parts of a compatibilizer, 1 part of titanium dioxide, 0.1 parts of an initiator, 0.2 parts of an antioxidant 168, 0.3 parts of an antioxidant 1076, and 0.5 parts of a lubricant.

[0060] The preparation method of PP composite material comprises the following steps:

[0061] S1. Mix PP resin, PS resin, reinforcing agent, compatibilizer, titanium dioxide, initiator, antioxidant 168, antioxidant 1076, and lubricant, and mix at 400-500rpm for 20min to obtain a mixture;

[0062] S2. The mixture was added to a twin-screw extruder, and the mixture was melt-extruded and granulated to obtain the PP composite material;

[0063] The temperatures of each section of the twin-screw extruder are 170-180°C, 180-190°C, 190-200°C, 200-210°C, 210-220°C, and the screw speed is 300-600rpm. Example 2

[0064] The difference between this embodiment and embodiment 1 is that: 30 parts of homopolymer polypropylene and 40 parts of polystyrene;

[0065] The rest is exactly the same as in Example 1. Example 3

[0066] The difference between this embodiment and embodiment 1 is that: 50 parts of homopolymer polypropylene and 20 parts of polystyrene;

[0067] The rest is exactly the same as in Example 1. Example 4

[0068] The difference between this embodiment and embodiment 1 is that: 10 parts of reinforcing agent (obtained in preparation example 2);

[0069] The rest is exactly the same as in Example 1. Example 5

[0070] The difference between this embodiment and embodiment 1 is that: 10 parts of reinforcing agent (obtained in preparation example 3);

[0071] The rest is exactly the same as in Example 1.

[0072] Comparative Example 1

[0073] The difference between this embodiment and embodiment 1 is that: 10 parts of reinforcing agent (obtained in preparation example 4);

[0074] The rest is exactly the same as in Example 1.

[0075] Comparative Example 2

[0076] The difference between this embodiment and embodiment 1 is that: 10 parts of reinforcing agent (obtained in preparation example 5);

[0077] The rest is exactly the same as in Example 1.

[0078] Comparative Example 3

[0079] The difference between this embodiment and embodiment 1 is that: 10 parts of reinforcing agent (including 6.7 parts of talc and 3.3 parts of basic magnesium sulfate whiskers);

[0080] The rest is exactly the same as in Example 1.

[0081] Results and Testing

[0082] Tensile strength, elongation at break: GB / T1040.1-2018, test conditions: 50mm / min;

[0083] Impact strength: GB / T 1843-2008, test conditions: 5.5J;

[0084] Oil corrosion resistance: The PP composite materials obtained in Examples 1-5 and Comparative Examples 1-3 were prepared into dumbbell-shaped tensile specimens (GB / T 1040.2-2022, 1A type specimens) and bent. The surface of the specimens was covered with medical gauze (one layer) and coated with edible blended oil. After the oil-treated specimens were placed at (23±2)°C and (50±10)%RH for 8 h, the blended oil on the specimens was wiped clean and then placed in an environment of (23±2)°C and (50±10)%RH for 24 h, and the tensile performance test was performed (GB / T1040.1-2018, test conditions: 50 mm / min);

[0085] Resistance to foaming agent corrosion: The PP composite materials obtained in Examples 1-5 and Comparative Examples 1-3 were prepared into specimens (GB / T1843-2008 unnotched specimens with dimensions of 10×80×4 mm) and placed in transparent glass containing foaming agent liquid (foaming agent composition: (CP: 245FA: LBA = 1:1:1)). Under the test condition of (2-8)°C, the specimens were sealed and immersed for 4 hours, and the changes in the state of the specimens and the foaming agent liquid were observed.

[0086] Light aging resistance: The PP composite materials obtained in Examples 1-5 and Comparative Examples 1-3 were prepared into color plates (GB / T16422.3-2022, size: 75×50×30 mm), which were placed in a UV aging box for accelerated aging treatment. The test conditions were wavelength: 340 nm, radiation intensity: 0.76 W / m 2 , illumination temperature: 60℃, condensation temperature: 50℃, test time: 8h illumination, 4h condensation, 4 cycles of testing, a total of 48h, the color difference value of the color plate before and after testing aging (△E= [(△L) 2 +(△a*) 2 + (△b*) 2 ]^ 1 / 2 ). The results are shown in Table 1.

[0087] Table 1

[0088]

[0089] From the data of Examples 1-5 in Table 1, it can be seen that the PP material prepared by the present invention has excellent performance in tensile strength, impact strength, elongation at break, resistance to foaming agent corrosion, aging resistance, as well as tensile strength and elongation at break after oil corrosion.

[0090] The reinforcing agent is obtained by introducing epoxy groups on the surface of talc powder and basic magnesium sulfate whiskers, and then further introducing phosphate-modified polyethyleneimine. PP resin, PS resin, reinforcing agent, compatibilizer and other additives are blended and extruded to obtain a PP composite material.

[0091] By comparing Example 1, Comparative Examples 1 and 2, it can be seen that the appropriate proportion of talcum powder and basic magnesium sulfate whisker has a significant effect on the material properties. Regardless of the lack of talcum powder (Comparative Example 1) or basic magnesium sulfate whisker (Comparative Example 2), the performance of the PP composite material is significantly reduced. However, when the two are used simultaneously within a certain proportion range, the performance of the PP composite material is significantly improved, with a synergistic enhancement effect.

[0092] By comparing Example 1 and Comparative Example 3, it can be seen that the introduction of epoxy group and phosphate-modified polyethyleneimine has a great influence on the performance of the PP composite material.

[0093] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A PP composite material for refrigerator liner, characterized in that: Homopolymer polypropylene 40 parts, polystyrene 30 parts, reinforcing agent 10 parts, compatibilizer 10 parts, titanium dioxide 1 part, initiator 0.1 parts, antioxidant 168 0.2 parts, antioxidant 1076 0.3 parts, lubricant 0.5 parts; The preparation method of the enhancer is as follows: The surfaces of talcum powder and basic magnesium sulfate whiskers are modified by epoxy silane coupling agent to obtain epoxy-modified composite powder; Polyethyleneimine modified with di-tert-butyl chloromethyl phosphate is reacted to obtain phosphate-modified polyethyleneimine; The reinforcing agent is obtained by reacting phosphate-modified polyethyleneimine with epoxy-modified composite powder; The mass ratio of the epoxy silane coupling agent, talcum powder and basic magnesium sulfate whisker is (0.1-0.5): (1-5): (1-5); The mass ratio of the polyethyleneimine to di-tert-butyl chloromethyl phosphate is 1:(1-3).

2. The PP composite material for refrigerator liner according to claim 1, characterized in that: The mass ratio of the phosphate-modified polyethyleneimine to the epoxy-modified composite powder is (0.5-2):

1.

3. The PP composite material for refrigerator liner according to claim 1, characterized in that: The compatibilizer is hydrogenated styrene-butadiene block copolymer (SEBS).

4. The PP composite material for refrigerator liner according to claim 1, characterized in that: The initiator is di-tert-butyl peroxide (DTBP); the lubricant is vinyl bisstearamide (EBS).

5. A method for preparing the PP composite material according to any one of claims 1 to 4, characterized in that , including the following steps: S1. homopolymer polypropylene, polystyrene, reinforcing agent, compatibilizer, titanium dioxide, initiator, antioxidant 168, antioxidant 1076, and lubricant are uniformly mixed to obtain a mixture; S2. The mixture was added to a twin-screw extruder, and the mixture was melt-extruded and granulated to obtain the PP composite material; Among them, the mixing speed in S1 is 400-500rpm, and the mixing time is 5-30min; The temperatures of each section of the twin-screw extruder in S2 are 170-180°C, 180-190°C, 190-200°C, 200-210°C, 210-220°C, and the screw speed is 300-600rpm.

Images