Polypropylene composition as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene composition as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The polypropylene composition is prepared from the following components in parts by weight: 44 to 78 parts of polypropylene resin, 15 to 40 parts of glass fiber, 3 to 8 parts of wollastonite, 3 to 5 parts of compatilizer, 0.03 to 0.1 part of zinc oxide, 0.05 to 0.2 part of aromatic carboxylic acid and 0.4 to 2 parts of processing aid, the molar ratio of zinc oxide to carboxylic acid groups in aromatic carboxylic acid is 1: (1.95-2.3); wherein the structure of the aromatic carboxylic acid is shown as a formula (I), R1 is methyl, carboxyl or hydrogen, and R2 is carboxyl. According to the polypropylene composition, melting is accelerated in the hot melting process of welding, meanwhile, residual stress is effectively reduced in the melting and cooling process, so that the welding strength is improved, serious whitening of welding seams can be effectively avoided, and the yield of products is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more particularly to a polypropylene composition, a preparation method thereof, and applications thereof. Background Art

[0002] Polypropylene material has the characteristics of low density, chemical resistance and excellent cost-effectiveness. It is widely used in many fields such as automobiles, home appliances, food, medical care, construction, etc.

[0003] Glass fiber reinforced polypropylene (GRP) is widely used in the manufacture of various components. Key components like waterway manifolds require high weld strength while minimizing the risk of severe whitening. Currently, hot plate welding is the primary welding method. However, in practice, existing GRP materials often suffer from poor welds, resulting in weld marks, reduced tensile strength, severe whitening, and increased costs.

[0004] Prior art discloses a hollow blow-molded automotive intake manifold material comprising polypropylene, high-melt-strength polypropylene, high-density polyethylene, glass fiber, wollastonite as a flow synergist, an acrylic-grafted polyolefin interfacial modifier, a nucleating agent, an antioxidant, and a lubricant. However, this material does not specifically address the technical issues of weld lines, reduced tensile strength, and severe whitening of welds during welding. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing polypropylene composition in that the products prepared during welding are prone to weld marks, reduced tensile strength, and serious whitening of the weld seams, and to provide a polypropylene composition that can reduce the occurrence of whitening of the weld seams while ensuring high welding strength.

[0006] Another object of the present invention is to provide a method for preparing the polypropylene composition.

[0007] Another object of the present invention is to provide an application of a polypropylene composition in the preparation of an automobile waterway manifold.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] A polypropylene composition comprising the following components, calculated by weight: 44-78 parts of polypropylene resin, 15-40 parts of glass fiber, 3-8 parts of wollastonite, 3-5 parts of a compatibilizer, 0.03-0.1 parts of zinc oxide, 0.05-0.2 parts of an aromatic carboxylic acid, and 0.4-2 parts of a processing aid;

[0010] The molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:(1.95-2.3);

[0011] The structure of the aromatic carboxylic acid is shown in the following formula (I):

[0012]

[0013] Wherein, R1 is methyl, carboxyl or hydrogen, and R2 is carboxyl.

[0014] In the present invention, R2 represents a substituent at the ortho, para or meta position of R1, and the number of R2 is 1.

[0015] The polypropylene composition of the present invention can improve the tensile strength of the weld line and avoid severe whitening of the weld. The applicant speculates that the principle may be as follows:

[0016] The aspect ratio structure and high thermal conductivity of wollastonite give the prepared material high rigidity and high welding strength, which helps to improve the durability and stability of the product; the aromatic carboxylic acid and zinc oxide react in situ to form an aromatic carboxylic acid zinc salt or its complex as a welding improver, which can effectively achieve the dispersion of the various components in the injection molded parts, improve the thermal stability of the material during the hot melt process of welding, and effectively reduce the residual stress during the melt cooling process, thereby improving the welding strength and effectively avoiding severe whitening of the weld, thereby improving the product yield.

[0017] In the polypropylene composition of the present invention, the polypropylene resin accounts for at least 40% by mass of the polypropylene composition.

[0018] Preferably, in the polypropylene composition of the present invention, the mass percentage of the polypropylene resin in the polypropylene composition is 44 to 80%.

[0019] Preferably, the polypropylene resin comprises 55-65 parts, the glass fiber comprises 10-25 parts, the wollastonite comprises 4-6 parts, the compatibilizer comprises 3-4 parts, the zinc oxide comprises 0.06-0.07 parts, and the processing aid comprises 1-1.5 parts.

[0020] Preferably, R1 is a carboxyl group.

[0021] More preferably, the aromatic carboxylic acid is one or more of phthalic acid and isophthalic acid.

[0022] Phthalic acid or isophthalic acid has better compatibility with polypropylene.

[0023] Still more preferably, the aromatic carboxylic acid is phthalic acid.

[0024] Preferably, the aspect ratio of the wollastonite is not greater than 16:1.

[0025] The aspect ratio of wollastonite refers to the ratio of the length to the diameter of the wollastonite crystal.

[0026] More preferably, the aspect ratio of the wollastonite is (6-15):1.

[0027] More preferably, the aspect ratio of the wollastonite is (6-9):1.

[0028] In order to improve the tensile strength and reduce the whitening length of the weld, the present invention selects wollastonite with an aspect ratio of (6 to 9):1, which can have better welding strength and weld quality.

[0029] Preferably, the compatibilizer is one or more of maleic anhydride grafted polypropylene and glycidyl methacrylate grafted polypropylene.

[0030] More preferably, the compatibilizer is maleic anhydride grafted polypropylene.

[0031] Preferably, the grafting rate of maleic anhydride in the maleic anhydride-grafted polypropylene is 0.5-1.5%. The grafting rate is tested by acid-base titration.

[0032] More preferably, the mass grafting rate of maleic anhydride in the maleic anhydride grafted polypropylene is 0.8 to 1.1%.

[0033] Preferably, in the glycidyl methacrylate grafted polypropylene, the mass grafting rate of glycidyl methacrylate is 0.5-1.5%. The grafting rate is tested by acid-base titration.

[0034] Preferably, the melt mass flow rate of the polypropylene resin is not higher than 50 g / 10 min, the test standard is ISO 1133-1-2011, and the test conditions are 230° C. / 2.16 kg.

[0035] More preferably, the melt mass flow rate of the polypropylene resin is 10 to 50 g / 10 min, the test standard is ISO 1133-1-2011, and the test conditions are 230° C. / 2.16 kg.

[0036] More preferably, the melt mass flow rate of the polypropylene resin is 10 to 30 g / 10 min, the test standard is ISO 1133-1-2011, and the test conditions are 230° C. / 2.16 kg.

[0037] The polypropylene resin has a lower flow rate and a higher molecular weight, which is conducive to the entanglement between molecules and improves the weld strength, thereby improving the mechanical properties of the composition and the tensile strength of the weld mark.

[0038] Preferably, the polypropylene resin is one or more of copolymer polypropylene resin and homopolypropylene resin.

[0039] More preferably, the polypropylene resin is a homopolymer polypropylene resin.

[0040] Preferably, the glass fiber is alkali-free chopped glass fiber.

[0041] Preferably, the processing aid is one or more of an antioxidant or a dispersant.

[0042] In practical applications, the antioxidant may be a hindered phenol or phosphite antioxidant.

[0043] The hindered phenol antioxidant may be antioxidant 1010. The phosphite antioxidant may be antioxidant 168.

[0044] In practical applications, the dispersant may be zinc stearate.

[0045] The present invention also protects a method for preparing the above-mentioned polypropylene composition, comprising the following steps: adding polypropylene resin, glass fiber, wollastonite, a compatibilizer, an aromatic carboxylic acid, zinc oxide, and a processing aid into an extruder, melt blending, and extruding to obtain a polypropylene composition, wherein the extrusion temperature is 160-200°C.

[0046] The extruder may be a twin-screw extruder.

[0047] The aspect ratio of the screw in the twin-screw extruder can be 30:1 to 40:1.

[0048] The speed of the screw in the twin-screw extruder can be 400 to 600 rpm.

[0049] The present invention also protects the use of any of the above-mentioned polypropylene compositions in the automotive and electronic equipment fields.

[0050] The polypropylene material prepared from the polypropylene composition of the present invention can be applied to the manufacturing and welding fields of polypropylene composite materials, such as hot plate welding, and is particularly suitable for applications requiring high welding strength, such as the automotive industry and electronic equipment manufacturing, and can effectively improve the product yield and reduce the scrap rate.

[0051] The present invention also protects the use of any of the above-mentioned polypropylene compositions in the preparation of waterway manifolds.

[0052] The present invention also protects a welded part, which is prepared using any one of the above polypropylene compositions.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The present invention discloses a polypropylene composition. Through the combined action of aromatic carboxylic acid and zinc oxide, the dispersion of various components in an injection molded part can be effectively achieved. The thermal stability of the material is improved during the hot melt process of welding. At the same time, the residual stress is effectively reduced during the melt cooling process, thereby improving the welding strength and effectively avoiding severe whitening of the weld, thereby improving the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a diagram of the appearance of a weld surface rated as level one in the weld surface appearance test of the present invention.

[0056] Figure 2 This is a diagram of the weld surface appearance state that is rated as level four in the weld surface appearance state test of the present invention. DETAILED DESCRIPTION

[0057] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0058] The melt flow rate was measured according to ISO 1133-1-2011 (230°C / 2.16 kg).

[0059] PP resin 1#: homopolymer PP HP500N, melt mass flow rate of 10 g / 10 min, CNOOC Shell Petrochemical Co., Ltd.

[0060] PP resin 2#: homopolymer PP Y26, melt mass flow rate of 30 g / 10 min, Sinopec Zhenhai Co., Ltd.

[0061] PP resin 3#: homopolymer PP H9018, melt mass flow rate of 50 g / 10 min, Sinopec Zhenhai Co., Ltd.

[0062] PP resin 4#: copolymer PP BX3500, melt mass flow rate is 10g / 10min, Sino-Korea Petrochemical Co., Ltd.

[0063] Glass fiber: ECS13-4.5-T538D alkali-free chopped glass fiber, Taishan Fiberglass.

[0064] Wollastonite 1#: aspect ratio 6:1, WL1250, Sibelco (Shanghai) Mining Co., Ltd.

[0065] Wollastonite 2#: aspect ratio 9:1, M4W 10992, IMIFA Mining Co., Ltd.

[0066] Wollastonite 3#: aspect ratio 15:1, HK 1250, Dalian Global Minerals Co., Ltd.

[0067] Compatibilizer 1#: maleic anhydride grafted polypropylene, CA100, maleic anhydride grafting rate of 1.0%, Arkema.

[0068] Compatibilizer 2#: glycidyl methacrylate grafted polypropylene, PX6006, the mass grafting rate of glycidyl methacrylate is 1.0%, LyondellBasell Industries.

[0069] Aromatic carboxylic acid 1#: Phthalic acid: CAS number 88-99-3, Aladdin Reagent Co., Ltd.

[0070] Aromatic carboxylic acid 2#: Isophthalic acid: CAS number 121-91-5, Aladdin Reagent Co., Ltd.

[0071] Aromatic carboxylic acid 3#: o-toluic acid: CAS number 118-90-1, Aladdin Reagent Co., Ltd.

[0072] Aromatic carboxylic acid 4#: p-Toluic acid: CAS number 99-94-5, Aladdin Reagent Co., Ltd.

[0073] Aromatic carboxylic acid 5#: Benzoic acid: CAS number 65-85-0, Aladdin Reagent Co., Ltd.

[0074] Aromatic carboxylic acid 6#: Terephthalic acid: CAS number 100-21-0, Aladdin Reagent Co., Ltd.

[0075] Zinc oxide: Guangzhou Luchang Chemical Co., Ltd.

[0076] Zinc phthalate, CAS number 2880-85-5, Achemica Switzerland.

[0077] Antioxidant: Composed of a hindered phenol and a phosphite antioxidant in a 1:1 mass ratio; commercially available and used in both the Examples and Comparative Examples. The hindered phenol antioxidant is Antioxidant 1010. The phosphite antioxidant is Antioxidant 168.

[0078] Dispersant: zinc stearate, commercially available and the same one was used in the parallel examples and comparative examples.

[0079] Examples 1 to 15

[0080] A polypropylene composition comprises the following components by weight: polypropylene resin, glass fiber, wollastonite, a compatibilizer, zinc oxide, aromatic carboxylic acid, and a processing aid, wherein the processing aid is an antioxidant and a dispersant.

[0081] The compositions of the polypropylene compositions are shown in Table 1 below.

[0082] The polypropylene composition is prepared by the following method: polypropylene resin, wollastonite, a compatibilizer, aromatic carboxylic acid, zinc oxide, an antioxidant, and a dispersant are weighed by weight and added to a high-speed mixer for mixing for 4 minutes. The mixture is then added to a twin-screw extruder with a length-to-diameter ratio of 40:1 for melt mixing and dispersion. The mixture is then plasticized in the twin-screw extruder at a temperature of 160-200°C and a screw speed of 400 rpm. Glass fiber is added through a side feed port of the twin-screw extruder, and the screw temperature of the side feed port is set at 180°C. The mixture is then pulled, cooled, pelletized, and dried to obtain a polypropylene composite material.

[0083] Table 1 Composition of the polypropylene composition of each embodiment (in parts by weight)

[0084]

[0085] Table 1

[0086]

[0087]

[0088] In Example 1, the molar ratio of zinc oxide to aromatic carboxylic acid 1# is 1:1, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.

[0089] In Example 2, the molar ratio of zinc oxide to aromatic carboxylic acid 1# is 1:0.98, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:1.96.

[0090] In Example 3, the molar ratio of zinc oxide to aromatic carboxylic acid 1# is 1:1, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.

[0091] In Examples 4 to 9, the molar ratio of zinc oxide to aromatic carboxylic acid 1# was 1:1, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid was 1:2.

[0092] In Example 10, the molar ratio of zinc oxide to aromatic carboxylic acid 2# is 1:1, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.

[0093] In Example 11, the molar ratio of zinc oxide to aromatic carboxylic acid 3# is 1:2, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.

[0094] In Example 12, the molar ratio of zinc oxide to aromatic carboxylic acid 4# is 1:2, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.

[0095] In Example 13, the molar ratio of zinc oxide to aromatic carboxylic acid 5# is 1:2, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.

[0096] In Example 14, the molar ratio of zinc oxide to aromatic carboxylic acid 6# is 1:1, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.

[0097] In Example 15, the molar ratio of zinc oxide to aromatic carboxylic acid 6# is 1:1.1, and the molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:2.2.

[0098] Comparative Examples 1 to 5

[0099] A polypropylene composition comprises the following components, calculated by weight: polypropylene resin, glass fiber, wollastonite, a compatibilizer, zinc oxide, aromatic carboxylic acid, and a processing aid. The processing aid is an antioxidant and a dispersant, which are the same as those used in the examples.

[0100] The compositions of the polypropylene compositions are shown in Table 2 below.

[0101] The polypropylene composition is prepared by the following method: polypropylene resin, wollastonite, a compatibilizer, aromatic carboxylic acid, zinc oxide, an antioxidant, and a dispersant are weighed by weight and added to a high-speed mixer for mixing for 4 minutes. The mixture is then added to a twin-screw extruder with a length-to-diameter ratio of 40:1 for melt mixing and dispersion. The mixture is then plasticized in the twin-screw extruder at a temperature of 160-200°C and a screw speed of 400 rpm. Glass fiber is added through a side feed port of the twin-screw extruder, and the screw temperature of the side feed port is set at 180°C. The mixture is then pulled, cooled, pelletized, and dried to obtain a polypropylene composite material.

[0102] Table 2 Composition of the polypropylene compositions of the comparative examples (in parts by weight)

[0103] Components Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PP resin 1# 60 60 60 60 60 fiberglass 22 22 22 22 22 Wollastonite 1# 5 5 5 0 5 Compatibilizer 1# 3 3 3 3 3 Aromatic carboxylic acid 1# / / 0.135 0.135 / zinc oxide / 0.065 / 0.065 / Zinc phthalate / / / / 0.2 antioxidants 1 1 1 1 1 dispersants 0.3 0.3 0.3 0.3 0.3

[0104] The difference between Comparative Example 1 and Example 1 is that no aromatic carboxylic acid 1# and zinc oxide are added.

[0105] Comparative Example 2 differs from Example 1 in that only zinc oxide is added, and aromatic carboxylic acid 1# is not added.

[0106] Comparative Example 3 differs from Example 1 in that only aromatic carboxylic acid 1# is added, and zinc oxide is not added.

[0107] Comparative Example 4 differs from the embodiment in that wollastonite is not added.

[0108] Comparative Example 5 differs from Example 1 in that aromatic carboxylic acid 1# and zinc oxide are replaced by zinc phthalate.

[0109] Result detection

[0110] The polypropylene compositions of the above examples and comparative examples were tested for relevant properties:

[0111] (1) Charpy notched impact strength: The test standard is ISO 179-2011, and the test condition is 23°C.

[0112] (2) Tensile strength: The test standard is ISO 527-2011, and the test condition is 23°C.

[0113] The welding performance of the polypropylene compositions of the above examples and comparative examples was tested:

[0114] First, a 100 mm × 40 mm × 4 mm original specimen was obtained by injection molding, and then hot plate welding was performed at 260°C to obtain a 198 mm × 40 mm × 4 mm test specimen with a welding mark. The melting time was 8 s and the curing time was 15 s.

[0115] Then perform the following test:

[0116] (3) Weld line tensile strength: The test standard is ISO 527-2011, and the test condition is 23°C.

[0117] (4) Welding surface appearance: Visual evaluation is performed, and the percentage of the whitened area of ​​the weld to the total weld length is calculated. The evaluation criteria are shown in Table 3 below.

[0118] Table 3

[0119] Whitening percentage 0～15％ 15～45％ 45～70％ 70～100％ Rating / Grade Level 1 Level 2 Level 3 Level 4

[0120] Among them, the appearance of the first-level welding surface is as follows Figure 1 As shown, the appearance of the welding surface of level 4 is as follows Figure 2 shown.

[0121] The specific test results of each embodiment and comparative example are described in Table 4 below:

[0122] Table 4

[0123]

[0124]

[0125] From the above results, it can be seen that the polypropylene composition of the present invention can improve the tensile strength of the weld mark, which can reach above 31 MPa, and improve the quality of the weld, reducing the occurrence of severe whitening of the weld.

[0126] As can be seen from Examples 1 and 4-6, the PP resin is a homopolymer polypropylene resin with a flow rate of 10-30 g / 10 min, which has better mechanical properties and higher weld line tensile strength. This is because the high molecular weight resin facilitates intermolecular entanglement and improves weld strength.

[0127] As can be seen from Examples 1 and 7-8, wollastonite with an aspect ratio of 6-9:1 exhibits superior weld strength and weld quality. This is because increasing the aspect ratio of wollastonite can improve the material's tensile strength. However, high aspect ratio wollastonite may cause high stress at the weld, leading to whitening of the weld.

[0128] It can be seen from Comparative Example 4 that without adding wollastonite, the rigidity and welding strength of the material cannot meet the requirements.

[0129] It can be seen from Comparative Example 5 that directly adding zinc phthalate does not improve the weld line tensile strength and weld quality. It is speculated that this is because the non-in-situ generated carboxylate has poor dispersibility, which in turn causes uneven distribution and affects the welding strength and weld quality.

[0130] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A polypropylene composition, characterized in that The composition comprises the following components by weight: 44-78 parts of polypropylene resin, 15-40 parts of glass fiber, 3-8 parts of wollastonite, 3-5 parts of compatibilizer, 0.03-0.1 parts of zinc oxide, 0.05-0.2 parts of aromatic carboxylic acid, and 0.4-2 parts of processing aid; The molar ratio of zinc oxide to the carboxylic acid group in the aromatic carboxylic acid is 1:(1.95-2.3); The structure of the aromatic carboxylic acid is shown in the following formula (I): Wherein, R1 is methyl, carboxyl or hydrogen, and R2 is carboxyl.

2. The polypropylene composition according to claim 1, wherein R1 is a carboxyl group.

3. The polypropylene composition according to claim 2, wherein The aromatic carboxylic acid is one or more of isophthalic acid and phthalic acid.

4. The polypropylene composition according to claim 1, wherein The aspect ratio of the wollastonite is no greater than 16:

1.

5. The polypropylene composition according to claim 1, wherein The compatibilizer is one or more of maleic anhydride grafted polypropylene and glycidyl methacrylate grafted polypropylene.

6. The polypropylene composition according to claim 1, wherein The melt mass flow rate of the polypropylene resin is 10 to 50 g / 10 min, the test standard is ISO 1133-1-2011, and the test conditions are 230° C. / 2.16 kg.

7. The polypropylene composition according to claim 1, wherein The processing aid is one or more of an antioxidant or a dispersant.

8. The method for preparing the polypropylene composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: adding polypropylene resin, glass fiber, wollastonite, compatibilizer, aromatic carboxylic acid, zinc oxide and processing aid into an extruder, and obtaining a polypropylene composition after melt blending and extrusion, wherein the extrusion temperature is 160-200°C.

9. Use of the polypropylene composition according to any one of claims 1 to 7 in the preparation of automobile waterway manifolds.

10. A welded part, characterized in that: The method is prepared using the polypropylene composition according to any one of claims 1 to 7.

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