Polypropylene composition, process for its preparation and use thereof

Abstract

The application discloses a kind of polypropylene composition and its preparation method and application, belong to high polymer material technical field, the product includes polypropylene resin 59~71 parts, glass fiber 20~40 parts, compatible agent 1~5 parts, epoxy resin 0.5~2 parts, phenolic resin 0.75~3 parts, acid absorbent 0.1~1 parts, interface modifier 0.1~1 parts, coupling agent 0.1~0.5 parts, by incorporating curing resin system in polypropylene matrix resin, while introducing interface modifier, coupling agent and acid absorbent component, so that the heat-aging resistance of product from inside to outside and solvent resistance significantly improve, service life is greatly extended, and appearance stability is strong, the degree of appearance degradation under harsh environment is small.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a polypropylene composition, its preparation method, and its application. Background Technology

[0002] Glass fiber reinforced polypropylene composites have good processing performance and excellent mechanical properties, and are theoretically very suitable for applications such as household appliances. However, the polypropylene matrix resin in this material is prone to degradation under heat and oxygen conditions due to the presence of active tertiary carbon atoms, and the glass fibers it contains have insufficient alkali resistance. Therefore, the heat and oxygen aging resistance and solvent resistance of the product are not ideal.

[0003] In addition to the polypropylene matrix resin, some processing aids in the product can also undergo catalytic hydrolysis under acidic or alkaline conditions, which not only leads to functional failure but also causes serious deterioration in the appearance of the product under these conditions. Summary of the Invention

[0004] Based on the deficiencies of the existing technology, the purpose of this invention is to provide a polypropylene composition. This product, by incorporating a curing resin system into a polypropylene matrix resin and introducing interface modifiers, coupling agents and acid scavengers, significantly improves the product's resistance to thermo-oxidative aging and solvent resistance from the inside out, greatly extends its service life, and exhibits strong appearance stability with minimal appearance degradation under harsh environments.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A polypropylene composition comprising the following components in parts by weight:

[0007] The composition includes 59-71 parts polypropylene resin, 20-40 parts glass fiber, 1-5 parts compatibilizer, 0.5-2 parts epoxy resin, 0.75-3 parts phenolic resin, 0.1-1 parts acid scavenger, 0.1-1 parts interface modifier, and 0.1-0.5 parts coupling agent.

[0008] The acid absorbent is at least one of hydrotalcite, zinc oxide, magnesium oxide, and aluminum oxide;

[0009] The interface modifier is at least one of carboxyl-terminated hyperbranched polyester and hydroxyl-terminated hyperbranched polyester.

[0010] To overcome the solvent resistance defect of glass fiber reinforced polypropylene composites, this invention introduces a specific ratio of phenolic resin and epoxy resin into the glass fiber reinforced polypropylene resin system. These two resins can dynamically solidify during product melt processing, strongly bonding with the glass fibers in the product components to form an interfacial protective film. This significantly reduces the impact of external factors on the glass fibers, thereby improving the product's solvent resistance, especially its resistance to alkaline solvents. On the other hand, the resin matrix and additives in the product contain acidic substances or free groups, such as those generated from catalyst residues. These components, especially acidic substances or acidic groups, are extremely prone to catalytic hydrolysis under alkaline solvent conditions, forming interfacial gaps / channels in the product, allowing solvents to penetrate into the product. Therefore, this invention introduces a specific inorganic acid absorbent. Regarding the adsorption of free radicals, these substances exhibit high adsorption efficiency and are more stable than organic adsorbents. They do not produce byproducts after adsorbing radicals, thus improving the product's internal environmental resistance. In addition to the dynamically curing resin and inorganic acid absorbent, to ensure the overall density of the components, this invention also incorporates a specific type of hyperbranched polyester for compounding. This component works in conjunction with the coupling agent to improve the interfacial strength between the resin matrix and the inorganic glass fiber, enhancing the interfacial density of the glass fiber reinforced product. This reduces solvent permeability, especially in alkaline solvent environments. Through the synergistic effect of these three components, the product exhibits excellent solvent resistance and resistance to heat and oxygen aging. Furthermore, due to the overall density and inertness of the product, its appearance remains largely unchanged, demonstrating good appearance stability.

[0011] Preferably, in the polypropylene composition, the epoxy resin is in the range of 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts by weight, or any two of these values; and the phenolic resin is in the range of 0.75 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts by weight, or any two of these values.

[0012] More preferably, in the polypropylene composition, the epoxy resin comprises 1 to 1.5 parts by weight and the phenolic resin comprises 1.5 to 2.25 parts by weight.

[0013] More preferably, the equivalent ratio of the hydroxyl groups in the phenolic resin to the epoxy groups in the epoxy resin is (0.8 to 1.2):1.

[0014] When phenolic resin and epoxy resin are in the above-mentioned proportions, they basically achieve complete curing reaction to form a cross-linked network. With the introduction of both and changes in the amount added, in addition to the improvement of the product's density and inorganic-organic interface strength, the overall compatibility, flowability and curing degree of the two resins are also changed. After optimization, the curing system formed by phenolic resin and epoxy resin with the above-mentioned weight ratio has a better comprehensive synergistic effect.

[0015] More preferably, the epoxy resin has an epoxy group equivalent of 150-250 g / eq, and the phenolic resin has a hydroxyl group equivalent of 90-180 g / eq.

[0016] More preferably, the epoxy resin is at least one of bisphenol A type epoxy resin and bisphenol F type epoxy resin.

[0017] More preferably, the phenolic resin is at least one of linear phenol-formaldehyde resin, linear bisphenol A-formaldehyde resin, and linear o-cresol-formaldehyde resin.

[0018] Preferably, the acid absorbent is hydrotalcite, and the molar ratio of magnesium oxide to aluminum oxide in the hydrotalcite is ≥3.

[0019] Preferably, the terminal carboxyl hyperbranched polyester and the terminal hydroxyl hyperbranched polyester are aromatic hyperbranched polyesters with a number-average molecular weight of 800-6500 g / mol and a molar number of carboxyl groups or molar number of hydroxyl groups of 5-25.

[0020] More preferably, the interface modifier is a carboxyl-terminated hyperbranched polyester.

[0021] More preferably, the number-average molecular weight of the terminal carboxyl hyperbranched polyester is 2000-3000 g / mol, and the number of carboxyl groups or hydroxyl groups per mole is 10-15.

[0022] Hyperbranched polyesters with different end groups have a certain impact on the interface modification effect of the product. Furthermore, under the preferred conditions, hyperbranched polyesters have a better degree of interface improvement in the product components and a better effect.

[0023] Preferably, the coupling agent is at least one selected from aminosilane coupling agents, vinylsilane coupling agents, methacryloxysilane coupling agents, titanate coupling agents, and aluminum-titanium silane coupling agents.

[0024] More preferably, the coupling agent is a vinylsilane coupling agent.

[0025] More preferably, the vinylsilane coupling agent is vinyltris(2-methoxyethoxy)silane.

[0026] As described above, in the polypropylene composition of the present invention, the hyperbranched polyester and the coupling agent have a synergistic effect, which can improve the interfacial strength between the polypropylene matrix resin and the glass fiber, thereby reducing the performance degradation caused by the penetration of external solvents into the internal components and wetting them. When the hyperbranched polyester is an aromatic hyperbranched polyester and the coupling agent is a vinyl silane coupling agent, the combination effect of the two is the best, especially for the greater improvement in the alkali resistance of the glass fiber in the product.

[0027] Preferably, the compatibilizer is maleic anhydride-grafted polypropylene with a grafting rate of 1-1.5%.

[0028] Maleic anhydride-grafted polypropylene is a commonly used compatibilizer in glass fiber reinforced polypropylene composites, and its theoretical compatibilization effect is also relatively high. However, the free maleic anhydride it contains is easily hydrolyzed in an alkaline environment, resulting in voids and gaps in its original location, which easily transport and store water and oxygen. The alkaline environment will catalyze the hydrolysis of maleic anhydride. However, the acid absorbent and dynamically cured resin system described in the technical solution of this invention can effectively inhibit the degree of hydrolysis of free maleic anhydride, thereby ensuring that maleic anhydride-grafted polypropylene can play a normal compatibilization role.

[0029] Preferably, the polypropylene resin has a melt flow rate of 15-150 g / 10 min at 230°C and 2.16 kg load, according to ISO 1133-2011.

[0030] More preferably, the melt flow rate of the polypropylene resin at 230°C and 2.16 kg load is one or any two of the following: 15 g / 10 min, 20 g / 10 min, 40 g / 10 min, 50 g / 10 min, 80 g / 10 min, 100 g / 10 min, 120 g / 10 min, and 150 g / 10 min.

[0031] Preferably, the polypropylene resin has a mass content of ≥50 wt% in the polypropylene composition.

[0032] Preferably, the glass fiber has an average diameter of 8–15 μm and an average length of 3–10 mm.

[0033] More preferably, the polypropylene composition further comprises 0.01 to 1 part of a processing aid, wherein the processing aid includes at least one of an antioxidant and a lubricant.

[0034] Based on the needs of the actual product, those skilled in the art may appropriately introduce some components commonly used in polypropylene products without affecting the product performance, such as antioxidants to improve the product's conventional oxidation resistance, lubricants to improve the product's processing performance, etc.

[0035] More preferably, the antioxidant is at least one of hindered phenolic antioxidants and phosphite antioxidants, and the lubricant is at least one of organosilicon lubricants and stearic acid lubricants.

[0036] Another object of the present invention is to provide a method for preparing the polypropylene composition, comprising the following steps:

[0037] The components are added to a screw extruder for melt extrusion and granulation to obtain the polypropylene composition.

[0038] Preferably, the heating temperature of the screw extruder is 100-220°C, and the screw speed is 350-450 rpm.

[0039] The preparation method of the polypropylene composition of the present invention is simple, requires little equipment, and can achieve industrial-scale production.

[0040] Another object of the present invention is to provide the use of the polypropylene composition in the manufacture of washing appliances.

[0041] The polypropylene composition of this invention introduces a curing resin system into the matrix resin, and simultaneously introduces interface modifiers, coupling agents, and acid scavengers. These three mechanisms synergistically enhance the heat and oxygen aging resistance and solvent resistance, especially alkaline solvent resistance, of glass fiber reinforced polypropylene resin products. Under the action of specific types of acid scavengers and interface modifiers, the chemical stability of the product is significantly improved from the inside out. It can be used for a long time in humid and hot environments or solvent environments, and its appearance will not deteriorate significantly. Therefore, it is very suitable for the manufacture of washing appliances that need to be used in humid / hot environments.

[0042] Preferably, the washing appliance includes at least one of a dishwasher, a washing machine, a dryer, and a sterilizing cabinet.

[0043] The beneficial effects of the present invention are that it provides a polypropylene composition, which, by incorporating a curing resin system into a polypropylene matrix resin and introducing hyperbranched polyester as an interface modifier, a complex coupling agent and an acid scavenger component, significantly improves the product's resistance to thermo-oxidative aging and solvent resistance from the inside out, greatly extends its service life, and has strong appearance stability with minimal appearance degradation under harsh environments. Detailed Implementation

[0044] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0045] Examples 1-13

[0046] An embodiment of the polypropylene composition, its preparation method and application described in this invention, wherein the composition of the polypropylene composition is shown in Table 1.

[0047] The method for preparing the polypropylene composition includes the following steps:

[0048] The components are mixed evenly, and then melt-extruded and granulated in a screw extruder to obtain the polypropylene composition.

[0049] During melt extrusion of the component, the temperature zones of the twin-screw extruder are set as follows: Zone 1: 120℃, Zone 2: 220℃, Zone 3: 220℃, Zone 4: 210℃, Zone 5: 210℃, Zone 6: 210℃, Zone 7: 210℃, Zone 8: 210℃, Zone 9: 210℃, Zone 10: 210℃. The screw speed is 400 rpm, and the screw length-to-diameter ratio is 40:1.

[0050] Comparative Examples 1-8

[0051] The only difference between each comparative example and the embodiment is the type and ratio of components, as shown in Table 2.

[0052] In the components described in each embodiment and comparative example,

[0053] The polypropylene resin 1 is PP Z30S produced by Sinopec, and its melt flow rate is 24.76 g / 10 min at 230℃ and 2.16 kg load according to ISO 1133-2011.

[0054] The polypropylene resin 2 is PP H32GA produced by Huajin Chemical, and its melt flow rate is 34.88 g / 10 min at 230℃ and 2.16 kg load according to ISO 1133-2011.

[0055] The glass fiber is ECS13-03-508A produced by Jushi Chemical Fiber, with an average diameter of 12μm and an average length of 4mm;

[0056] The compatibilizer is AD105 produced by Nanhai Baichen Polymer Materials Co., Ltd., which is maleic anhydride-grafted polypropylene with a grafting rate of 1.2%.

[0057] The epoxy resin is 0164 (E-51) produced by Nantong Xingchen, a bisphenol A epoxy resin with an epoxy group equivalent of 183-190 g / eq.

[0058] The phenolic resin is PF-8211, a linear bisphenol A phenolic resin produced by Shandong Jiaying Chemical Technology Co., Ltd., with a hydroxyl equivalent of 115-120 g / eq.

[0059] The acid absorbent 1 is DHT-4A-2 produced by Kyowa Chemical, which is a hydrotalcite, magnesium aluminum silicate with an average particle size of 0.3 μm and a molar ratio of magnesium oxide to aluminum oxide of 4.3.

[0060] The acid absorbent 2 is BAO-05 zinc oxide produced by Zhuzhou Zexiang Industry, with an average particle size of 0.2μm;

[0061] The acid absorbent 3 is magnesium oxide produced by Xingtai Magnesium Chemical Co., Ltd., with an average particle size of 0.3 μm.

[0062] The acid absorbent 4 is BS-3818 produced by Bailihe Chemical, an organic acid absorbent, calcium stearate. This product is ground and sieved before use, and the average particle size is 0.3μm.

[0063] The interface modifier 1 is Hyper C102 produced by Wuhan Hyperbranching, a carboxyl-terminated hyperbranched polyester with a number-average molecular weight of 2600 g / mol and a number of 12 carboxyl groups per mole.

[0064] The interface modifier 2 is HyPer H302 produced by Wuhan Hyperbranching, a hydroxyl-terminated hyperbranched polyester with a number-average molecular weight of 2500 g / mol and a molar number of hydroxyl groups of 11 / mol.

[0065] The interface modifier 3 is HyPer C103 produced by Wuhan Hyperbranching, a carboxyl-terminated hyperbranched polyester with a number-average molecular weight of 6400 g / mol and a number of 24 carboxyl groups per mole.

[0066] The interface modifier 4 is HyPer C101 produced by Wuhan Hyperbranching, a carboxyl-terminated hyperbranched polyester with a number-average molecular weight of 1000 g / mol and a number of 6 carboxyl groups per mole.

[0067] The interface modifier 5 is erucic acid amide produced by Hedaxipu Chemical.

[0068] The interface modifier 6 is HyPer U102, a hyperbranched unsaturated resin produced by Wuhan Hyperbranching.

[0069] The coupling agent 1 is SG-SI 172, vinyltris(2-methoxyethoxy)silane, produced by Nanjing Shuguang Silane Chemical Co., Ltd.

[0070] The coupling agent 2 is JH-A110, aminopropyltriethoxysilane, produced by Jingzhou Jianghan Fine Chemical Co., Ltd.

[0071] The coupling agent 3 is TM38S, a pyrophosphate type titanate coupling agent produced by Yizheng Chemical.

[0072] The processing aid is a mixture of BASF's hindered phenolic antioxidant and phosphite antioxidant: antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0073] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0074] Table 1

[0075]

[0076]

[0077] Table 2

[0078] Components by weight Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Polypropylene resin 65 65 65 65 65 65 65 65 Fiberglass 30 30 30 30 30 30 30 30 compatibilizer 3 3 3 3 3 3 3 3 Epoxy resin 1 0 3 1 1 1 1 1 Phenolic resin 0 1 4.5 1.5 1.5 1.5 1.5 1.5 Acid absorbent 1 0.3 0.3 0.3 0.3 0.3 0.3 Acid absorbent 4 0.3 Interface Modifier 1 0.3 0.3 0.3 0.3 0.3 Interface modifier 5 0.3 Interface Modifier 6 0.3 Coupling agent 1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Processing aids 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3

[0079] To verify the performance of the polypropylene composition described in this invention, the products prepared in each example and comparative example were subjected to the following performance tests, with the specific steps as follows:

[0080] (1) Alkali extraction test: Each product was injection molded into a test square plate of 50*80*2mm, and then continuously immersed in a sodium hydroxide solution of pH=11 at 70℃ for 40 days. After that, it was transferred to an oven at 150℃ and left to stand. The time taken to record when the powdery area on the surface of the square plate reached 5% was recorded.

[0081] (2) Thermo-oxidative aging test: Each product was injection molded into a 50*80*2mm test square plate, and then transferred to an oven at 150℃ to stand. The time taken to record when the powdery area on the surface of the square plate reached 5% was recorded.

[0082] (3) Color difference test: Each product was injection molded into a test square plate of 50*80*2mm, and then continuously immersed in a sodium hydroxide solution of pH=11 at 70℃ for 40 days. The samples before and after immersion were tested according to ASTM D2244-21 standard. The color difference was tested using a colorimeter with a light source of D65 / 10° and a measuring aperture of 25.4mm.

[0083] The test results are shown in Tables 3 and 4.

[0084] Table 3

[0085]

[0086] Table 4

[0087]

[0088] As can be seen from Tables 3 and 4, the polypropylene composition of the present invention exhibits excellent alkali extraction resistance and thermo-oxidative aging resistance. During alkali extraction testing, the pulverization time can reach 1200 hours or more, with a maximum of over 1500 hours; during thermo-oxidative aging testing, the pulverization time can reach over 1450 hours, with a maximum of over 1600 hours. Furthermore, after long-term immersion in alkali solution, the product shows minimal color difference change, with ΔE maintained within the range of 5.5–6.7, demonstrating excellent overall performance. According to Examples 1, 4–5, and Comparative Examples 4–5, the introduction of an acid scavenger in the composite resin system of the present invention is crucial for the product's appearance stability. This acid scavenger must be inorganic; otherwise, as shown in Comparative Example 5, an organic acid scavenger was introduced based on Comparative Example 4, and even if the pulverization resistance time met the standard, the color difference change did not show significant improvement. As can be seen from Examples 1, 6-8, and Comparative Examples 6-8, when an unsuitable interface modifier is used, the improvement in the product's alkali resistance and appearance stability is not significant. Even when using hyperbranched polyesters with similar structures, if they are not terminal hydroxyl or carboxyl-terminated hyperbranched polyesters, they still cannot achieve similar alkali resistance and appearance stability as the product described in this invention. Furthermore, using an unsuitable interface modifier can even degrade the environmental resistance of the matrix resin itself. As can be seen from Examples 1 and 9-10, different coupling agents exhibit different synergistic effects in the resin system described in this invention. Relatively speaking, the use of vinylsilane coupling agents is quite effective.

[0089] The introduction of the dynamically curing resin component in the product of this invention is key to improving the product's resistance to alkali, thermo-oxidative aging, and appearance stability. As shown in Comparative Examples 1 and 2, without epoxy resin and phenolic resin, the expected dynamically curing resin system cannot be formed. The final product's alkali extraction pulverization time is less than 1000 hours, thermo-oxidative aging pulverization time is less than 1450 hours, and the appearance color difference ΔE reaches more than 8. With the introduction of the two resins, as shown in Examples 1 and 11-13, the various properties of the product are significantly improved. However, when the amount of these two resins gradually increases to an excessive level, as shown in Comparative Example 3, the various properties of the product will drop sharply. Therefore, the amount of the two resins added must be maintained within a limited range.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene composition, characterized in that, The components include the following parts by weight: The composition includes 59-71 parts polypropylene resin, 20-40 parts glass fiber, 1-5 parts compatibilizer, 0.5-2 parts epoxy resin, 0.75-3 parts phenolic resin, 0.1-1 parts acid scavenger, 0.1-1 parts interface modifier, and 0.1-0.5 parts coupling agent. The acid absorbent is at least one of hydrotalcite, zinc oxide, magnesium oxide, and aluminum oxide; The interface modifier is at least one of carboxyl-terminated hyperbranched polyester and hydroxyl-terminated hyperbranched polyester.

2. The polypropylene composition according to claim 1, characterized in that, In the polypropylene composition, the epoxy resin is present in parts by weight of 1 to 1.5 parts, and the phenolic resin is present in parts by weight of 1 to 1.5 parts.

3. The polypropylene composition according to claim 1, characterized in that, The acid absorbent is hydrotalcite.

4. The polypropylene composition according to claim 1, characterized in that, The terminal carboxyl hyperbranched polyester and terminal hydroxyl hyperbranched polyester are aromatic hyperbranched polyesters with a number average molecular weight of 800~6500 g / mol and a molar number of carboxyl groups or molar number of hydroxyl groups of 5~25.

5. The polypropylene composition according to claim 1, characterized in that, The coupling agent is at least one of aminosilane coupling agents, vinylsilane coupling agents, methacryloxysilane coupling agents, and titanate coupling agents.

6. The polypropylene composition according to claim 1, characterized in that, Includes at least one of the following (a) to (d): (a) The compatibilizer is maleic anhydride-grafted polypropylene with a grafting rate of 1-1.5%; (b) The polypropylene resin, according to ISO 1133-2011, has a melt flow rate of 15~150 g / 10 min at 230°C and 2.16 kg load; (c) The glass fiber has an average diameter of 8~15μm and an average length of 3~10mm; (d) The polypropylene composition further includes 0.01 to 1 part of processing aids, wherein the processing aids include at least one of antioxidants and lubricants.

7. The method for preparing the polypropylene composition according to any one of claims 1 to 6, characterized in that, Includes the following steps: The components are added to a screw extruder for melt extrusion and granulation to obtain the polypropylene composition.

8. The use of the polypropylene composition according to any one of claims 1 to 6 in the preparation of washing appliances.

9. The application as described in claim 8, characterized in that, The washing appliances include at least one of washing machines, dishwashers, dryers, and sterilizing cabinets.

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