High-polarity polypropylene material and preparation method thereof

Abstract

The present disclosure provides a polypropylene modified material, the polypropylene modified material comprises, based on the total weight of the polypropylene modified material, 70-90 wt% of a polypropylene matrix resin and 2-10 wt% of a multifunctional graft modifier, the multifunctional graft modifier comprises a first monomer, a second monomer and a third monomer, the weight ratio of the first monomer to the second monomer to the third monomer is (1-3): (0.5-1.5): (0.3-0.6), the first monomer comprises an anhydride monomer, the second monomer comprises an acrylate monomer containing an epoxy group, and the third monomer comprises an acrylate monomer containing a hydroxyl group. The invention also provides a preparation method and a product of the polypropylene modified material. The polypropylene modified material has the advantages of being high in polarity, capable of being directly used for material processing performance of bonding and / or spraying and the like, and is suitable for automobile exterior trimming parts, electric appliance products and the like.

Description

Technical Field

[0001] The present disclosure relates to a sprayable polypropylene modified material and its preparation method. The polypropylene modified material disclosed in the present disclosure has advantages such as high polarity and material processing properties that can be directly used for bonding and / or spraying, and is suitable for automotive exterior parts, electrical products, etc. Background Art

[0002] With the increasingly urgent demand for lightweighting and cost control in the field of electronic appliances, polypropylene (PP) is gradually replacing traditional engineering plastics (such as PC and ABS) due to its low density and low cost. However, the low surface polarity and strong chemical inertness of PP materials lead to significant defects in practical applications. PP has weak interfacial bonding with adhesives, which is prone to debonding problems (for example, insufficient sealing due to adhesive failure after encapsulation of electronic components), and poor bonding performance. When used for spraying, it has insufficient adhesion, poor surface wettability, and the coating is easy to peel off. In order to improve polarity, additional corona treatment, flame treatment or primer process is usually required, which increases production costs (approximately 20%-30%) and process complexity, and the cost of secondary processing is high.

[0003] The root of this problem lies in the lack of polar groups in PP molecular chains, resulting in low surface energy (typically <30 mN / m), making it difficult to form effective interfacial interactions with polar materials. Existing technologies for increasing the polarity of PP materials still suffer from low grafting yields and limited polarity enhancement.

[0004] Therefore, there is an urgent need to address the problems of poor bonding performance, insufficient spray adhesion, low surface polarity, and weak interfacial bonding of PP materials in this field. To this end, the present disclosure provides a highly polar PP modified material that can be directly bonded and sprayed. Summary of the Invention

[0005] A first aspect of the present disclosure provides a polypropylene modified material, comprising, based on the total weight of the polypropylene modified material, 70-90 wt% of a polypropylene base resin and 2-10 wt% of a multifunctional graft modifier, wherein the multifunctional graft modifier comprises a first monomer, a second monomer, and a third monomer, wherein the weight ratio of the first monomer, the second monomer, and the third monomer is (1-3):(0.5-1.5):(0.3-0.6), wherein the first monomer comprises an anhydride monomer, the second monomer comprises an epoxy group-containing acrylate monomer, and the third monomer comprises a hydroxyl group-containing acrylate monomer.

[0006] A second aspect of the present disclosure provides a method for preparing a polypropylene modified material, comprising melt-plasticizing a polypropylene matrix resin; injecting a multifunctional graft modifier into the molten polypropylene matrix resin to carry out a grafting reaction; optionally dynamically crosslinking the product obtained in step 2 under the action of a dynamic crosslinking agent; optionally injecting a functionalized filler into the product obtained in the previous step; and extruding and granulating the obtained product to obtain the polypropylene modified material.

[0007] The third aspect of the present disclosure provides an article prepared from the polypropylene modified material described in the present disclosure. DETAILED DESCRIPTION

[0008] The inventors of this disclosure conducted in-depth research on PP materials and discovered that modifying polypropylene using a multifunctional synergistic grafting system consisting of an anhydride primary monomer, an epoxy-containing acrylate monomer, and a hydroxyl-containing acrylate monomer as auxiliary monomers can significantly improve the surface polarity of PP materials and enhance their compatibility with various adhesives and coatings. This disclosure was completed based on this research.

[0009] The components of the polypropylene modified material disclosed herein are described in detail below:

[0010] Polypropylene matrix resin

[0011] Polypropylene (abbreviated as PP) is a semi-crystalline thermoplastic polymer made from propylene monomer through addition polymerization. It is used to provide the main structure of the material and ensure processing performance and mechanical strength. A polyolefin elastomer containing a grafting group can be added to the polypropylene matrix resin to increase the compatibility of non-polar / polar components, thereby improving the compatibility of polypropylene with polar monomers and inhibiting phase separation. Preferably, the polyolefin elastomer containing a grafting group is POE-g-MAH, i.e., a polyolefin elastomer grafted with maleic anhydride. Ethylene-vinyl acetate copolymer (EVA) can also be added to improve melt strength and prevent spray sagging.

[0012] Suitable polypropylene resins include, but are not limited to, homopolymer polypropylene (PPH), block copolymer polypropylene (PPB), and random copolymer polypropylene (PPR).

[0013] In one embodiment of the present disclosure, the polypropylene matrix resin comprises homopolypropylene, maleic anhydride grafted polyolefin elastomer, and ethylene-vinyl acetate copolymer. The weight ratio of the homopolypropylene, maleic anhydride grafted polyolefin elastomer, and ethylene-vinyl acetate copolymer is (70-90): (3-10): (2-7), preferably (80-85): (5-8): (3-5).

[0014] Multifunctional group synergistic grafting modifier

[0015] The multifunctional grafting modifier disclosed herein comprises three or more functional grafting monomers, preferably an anhydride monomer, an epoxy-containing acrylate monomer, and a hydroxyl-containing acrylate monomer. Multi-monomer grafting can increase the surface oxygen content of polypropylene by 85% and reduce the contact angle from 85° to 52°.

[0016] The anhydride compound includes, but is not limited to, acetic anhydride, maleic anhydride, succinic anhydride, propionic acid glycosides, itaconic anhydride, and malic anhydride. Preferably, the anhydride compound is maleic anhydride monomer (MAH). Maleic anhydride monomer is grafted onto polypropylene (PP) molecular chains through a chemical reaction, introducing carboxylic acid groups (-COOH) to increase polarity. This basic polarity modification method addresses the surface inertness of PP.

[0017] Epoxy-containing acrylate monomers are used to introduce epoxy groups into PP materials. These epoxy groups include, but are not limited to, ethylene oxide, glycidyl oxide, and butyl oxide. Epoxy-containing acrylate monomers useful in the present invention include, but are not limited to, glycidyl methacrylate and glycidyl acrylate. Preferably, the epoxy-containing acrylate monomer is glycidyl methacrylate (GMA). GMA is a functional monomer containing glycidyl oxide, and synergistically grafted with MAH enhances interfacial reactivity. The introduction of epoxy groups improves chemical bonding with adhesives / coatings.

[0018] Hydroxyl-containing acrylic monomers are used to introduce hydroxyl groups into PP materials. These include, but are not limited to, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, and hydroxybutyl acrylate. Preferably, the hydroxyl-containing acrylic monomer is hydroxyethyl acrylate (HEA). HEA is an acrylic monomer containing a hydroxyl (-OH) group, which provides hydrogen bonding sites after grafting. This increases the surface hydroxyl density, improving hydrophilicity and spray wettability.

[0019] In a specific embodiment of the present disclosure, the multifunctional graft modifier includes a first monomer, a second monomer and a third monomer, and the weight ratio of the first monomer, the second monomer and the third monomer is (1-3): (0.5-1.5): (0.3-0.6), wherein the first monomer includes an anhydride monomer, the second monomer includes an epoxy group-containing acrylate monomer, and the third monomer includes a hydroxyl group-containing acrylate monomer.

[0020] In a specific embodiment of the present disclosure, the first monomer includes at least one anhydride compound selected from maleic anhydride, itaconic anhydride, succinic anhydride, and malic anhydride.

[0021] In a specific embodiment of the present disclosure, the second monomer includes at least one glycidyl ester monomer selected from glycidyl methacrylate and glycidyl acrylate.

[0022] In a specific embodiment of the present disclosure, the third monomer includes at least one monomer selected from hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0023] In a preferred embodiment of the present disclosure, the multifunctional graft modifier comprises maleic anhydride monomer, glycidyl methacrylate monomer, and hydroxyethyl acrylate monomer. Preferably, the weight ratio of the maleic anhydride monomer, glycidyl methacrylate monomer, and hydroxyethyl acrylate monomer is 2:1:(0.3-0.6).

[0024] In a preferred embodiment of the present disclosure, the weight ratio of the polypropylene base resin to the multifunctional graft modifier is 10:1-50:1, preferably 15:1-35:1, and more preferably 25:1-30:1.

[0025] Functionalized fillers

[0026] In the present disclosure, functionalized fillers can be further added to strengthen the interface of the PP material. In a specific embodiment of the present disclosure, the polypropylene modified material also includes 1-3% by weight of a functionalized filler. The filler includes but is not limited to silica, montmorillonite, talc, wollastonite, calcium carbonate, barium sulfate, magnesium sulfate and calcium sulfate. Functional groups that can be used for functionalized fillers include but are not limited to amino, hydroxyl, carboxyl and the like. The functionalized filler includes amino-modified silica surface-modified with a silane coupling agent. Preferably, the functionalized filler is amino-modified nano-silica particles surface-modified with a silane coupling agent. The functionalized filler forms a chemical bond with the polypropylene graft chain, avoiding the interface defects of physical blending, improving the surface roughness and providing a mechanical anchoring effect.

[0027] Dynamic crosslinker

[0028] Cross-linking agents can produce chemical bonds between linear molecules, connecting the linear molecules together. The polymer segments that undergo cross-linking reactions form a three-dimensional cross-linked network structure to improve material performance.

[0029] In a specific embodiment of the present disclosure, the polypropylene modified material further comprises 0.1-1 wt % of a dynamic cross-linking agent.

[0030] In the present disclosure, dynamic crosslinkers refer to lipoic acid derivative dynamic crosslinkers. Lipoic acid derivatives are polymers based on lipoic acid that contain reversible disulfide bonds (-SS-) that can be reversibly broken and reorganized when heated / cooled. Under high-temperature processing conditions, the reversible disulfide bonds in the dynamic crosslinker break, reducing the melt viscosity and making the material easier to extrude and mold. Under low-temperature conditions after cooling, the disulfide bonds reorganize to form a crosslinked network, protecting the grafted polar groups (-COOH, epoxy, -OH) and preventing them from being "buried" in the matrix due to molecular chain relaxation, thereby maintaining high surface polarity for a long time. Dynamic crosslinkers can also inhibit high-temperature degradation. Since the PP grafting reaction needs to be carried out at 190-200°C, high temperatures in traditional processes will cause PP molecular chains to break, melt strength to decrease, polar groups to thermally decompose, and form bubble defects. Dynamic crosslinkers can shorten high-temperature exposure time and reduce degradation risks by reorganizing at low temperatures of 170-180°C.

[0031] The lipoic acid derivatives include but are not limited to lipoic acid-polycaprolactone copolymers, polyurethane-lipoic acid copolymers, lipoic acid-styrene copolymers, etc. In one embodiment of the present disclosure, the lipoic acid derivative dynamic crosslinker includes lipoic acid-polycaprolactone copolymers.

[0032] Optional additives

[0033] Additives include, but are not limited to, initiators, compatibilizers, UV absorbers, antioxidants, lubricants, masterbatches, surfactants, and the like, and are used to improve the PP material's thermal oxidative aging resistance, weathering resistance, and processability. There are no specific limitations on the additives used in the PP material of the present disclosure; various commercially available additives may be used, as long as they do not limit the objectives of the present invention.

[0034] In a preferred embodiment of the present disclosure, the polypropylene modified material comprises:

[0035]

[0036] The functionalized filler is amino-type nano-silica pretreated with a silane coupling agent, the dynamic cross-linking agent is a thioctic acid-polycaprolactone copolymer, and the initiator is dicumyl peroxide.

[0037] The method for preparing a polypropylene modified material disclosed herein comprises the steps of melt-plasticizing a polypropylene matrix resin; injecting a multifunctional graft modifier into the melted polypropylene matrix resin to carry out a grafting reaction; optionally subjecting the product obtained in step 2 to dynamic crosslinking under the action of a dynamic crosslinking agent; optionally injecting a functionalized filler into the product obtained in the aforementioned step; and extruding and granulating the obtained product to obtain the polypropylene modified material.

[0038] Preferably, the grafting reaction step and the dynamic crosslinking step are performed separately. The preparation method can be performed using a twin-screw extruder. A segmented temperature-controlled twin-screw extruder process is employed, whereby the twin-screw extruder is divided into sections and set to different temperatures to achieve the functions of melting, grafting, and dynamic crosslinking, respectively.

[0039] Preferably, the reaction temperature of the grafting reaction zone is 190-200° C., and the temperature of the dynamic crosslinking zone is 170-180° C., at which the lipoic acid derivatives form a crosslinked network through disulfide bond recombination.

[0040] In a preferred embodiment of the present disclosure, the dynamic crosslinking step is performed at a temperature of 170-180°C for 1200-1500s -1 carried out at a shear rate of .

[0041] Various products can be prepared using the PP material described in the present disclosure. The products can be prepared by directly bonding and / or spraying the PP material described in the present disclosure onto the products.

[0042] Extrusion molding can be carried out using methods and equipment known in the art. For example, the extrusion step can be carried out using a twin-screw extruder, preferably a conical twin-screw extruder. Those skilled in the art can adjust the reaction conditions and equipment parameters used based on their common technical knowledge as long as the purpose of the present disclosure can be achieved.

[0043] In a preferred embodiment of the present disclosure, the process flow for preparing PP material includes raw material pretreatment, premixing, main feeding, melt plasticization, grafting reaction, dynamic crosslinking, nanofiller injection, extrusion granulation and pelletizing.

[0044] The products can be applied to automotive exterior parts (such as bumpers and door handles) and household appliance housings (such as washing machine panels and air conditioner housings), especially high-end components such as smart home touch panels that have strict requirements for direct spraying and high-strength bonding, which can significantly reduce secondary processing costs and improve product reliability.

[0045] The beneficial effects of the present disclosure are:

[0046] Through collaborative innovation of material formulation and process, the present invention significantly improves the surface polarity of PP (surface energy ≥48mN / m), allowing direct bonding and spraying without secondary treatment; breaks through the bottleneck of grafting rate (5%-8%), and broadens the interface bonding mechanism through the collaboration of multiple functional groups; solves the problem of processing stability, maintaining high melt fluidity (MFI ≥15g / 10min) while avoiding PP degradation; eliminates nanofiller interface defects and achieves long-term interface strengthening through chemical bonding.

[0047] In this disclosure, the terms "comprising," "including," or "using" indicate that various components can be used together in the mixture or composition of this disclosure. It should be understood that the degrees of "high," "low," etc., used in this disclosure are well known in the art. For example, with respect to "high polarity," a person skilled in the art can determine whether a particular PP material is a high-polarity material based on existing materials. Specifically, in this disclosure, a high-polarity PP material refers to a PP material having a surface energy of no less than 40 mN / m.

[0048] Unless otherwise specified, all raw materials disclosed herein can be obtained commercially or prepared according to conventional methods in the art. Unless otherwise defined or indicated, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods disclosed herein. Other aspects of the present disclosure will be apparent to those skilled in the art from the disclosure herein.

[0049] The present disclosure will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present disclosure only and are not intended to limit the scope of the present disclosure. The experimental methods for which specific conditions are not specified in the following examples are generally determined in accordance with national standards. If there are no corresponding national standards, the methods are carried out in accordance with general international standards, conventional conditions, or the conditions recommended by the manufacturer. Unless otherwise stated, all parts are by weight, all percentages are by weight, and the polymer molecular weight is the number average molecular weight.

[0050] Raw material source and preparation:

[0051] Homopolymer polypropylene (PP): melt index is 15-20 g / 10 min, with high crystallinity, product brand PP 3155, purchased from ExxonMobil.

[0052] Maleic anhydride (MAH): purity ≥99%, particle size ≤50 μm, product brand Luperox 101, purchased from BASF;

[0053] Glycidyl methacrylate (GMA): purity ≥98%, epoxy value 0.6-0.8 mol / 100 g, product brand GMA 950, purchased from Dow Chemical Company;

[0054] Hydroxyethyl acrylate (HEA): purity ≥95%, hydroxyl content 8-10 wt%, product brand HEA-10, purchased from Nippon Shokubai Co., Ltd.

[0055] Dicumyl peroxide (DCP): purity ≥98%, half-life (175°C) 1 min, product brand Perkadox BC-FF, purchased from AkzoNobel;

[0056] Aminated silica (SiO2): particle size 20-50 nm, amino content ≥1.5 mmol / g, product brand AEROSILR812, purchased from Evonik Industries AG;

[0057] Silane coupling agent: product brand KH550, purchased from Shandong Shuntai New Materials Co., Ltd.

[0058] Lipoic acid-polycaprolactone copolymer: Polycaprolactone (brand 6500, purchased from Perstorp, Sweden) was added with excess ethylenediamine (EDA, analytical grade, molecular weight 60.1, purchased from Maoming Chuizi New Materials Co., Ltd.) and dehydrated at 130°C under nitrogen for 3 hours to obtain amino-terminated PCL (PCL-NH2). LA-PCL copolymer with a molecular weight of 3000-5000 g / mol and a disulfide bond density of ≥2.0 mmol / g was prepared by chemical coupling of amino-terminated polycaprolactone with lipoic acid (α-lipoic acid, light yellow powdery crystals, molecular weight 206.32, purchased from Xi'an Rongzhen Biotechnology Co., Ltd.) at a molar ratio of 1:1 in tetrahydrofuran (THF, molecular weight 72.1, purchased from Dongguan Shenghe Chemical Co., Ltd.) for 12 hours.

[0059] POE-g-MAH: MAH grafting rate 1.2-1.5%, melt index 5-10 g / 10 min, product brand TAFMERMH7020, purchased from Mitsui Chemicals, Inc.

[0060] EVA (ethylene vinyl acetate): VA content 28-32%, melt index 6-10 g / 10 min, product brand Elvax3175, purchased from DuPont.

[0061] Product performance test:

[0062] Grafting rate: The grafting rate of the product was tested according to the ASTM D664 acid-base titration method. 1g of modified PP was dissolved in 100mL of xylene (dissolved at 130℃), and excess KOH-ethanol solution (0.1mol / L) was added. The mixture was refluxed for 2h to completely saponify the unreacted maleic anhydride. The remaining KOH was back-titrated with a standard HCl solution (0.05mol / L). The pink color of the phenolphthalein indicator (endpoint pH = 8.3) disappeared. The grafting rate was calculated according to the following formula:

[0063] 3. Calculation:

[0064]

[0065] (M MAH =98.06 g / mol, W 样品 is the sample mass),

[0066] Among them, V 样品 V is the volume of HCl standard solution consumed in the titration of the above solution. 空白 The volume of the above solution of equal volume consumed when titrating the HCl standard solution without adding modified PP; C HCl The concentration of HCl standard solution is 0.05mol / L, M MAH : Maleic anhydride molar mass, 98.06g / mol,

[0067] W 样品 The mass of the PP sample is 1.0 g;

[0068] (2) Water drop angle: The surface contact angle was tested according to the ASTM D7334 test standard. PP was injection molded into a flat sheet (50 mm × 50 mm × 2 mm), ultrasonically cleaned with anhydrous ethanol, and then dried. Using a contact angle meter (Dataphysics OCA50), 2 μL of deionized water (25°C) was added. After standing for 10 seconds, the contact angle was read and the average value of 5 points was taken. The surface contact angle refers to the angle formed by a water drop on the surface of the material and is used to characterize the hydrophilicity of the material. The smaller the angle, the stronger the hydrophilicity.

[0069] (3) Surface energy: Deionized water (polar liquid, surface energy γ L =72.8mN / m, dispersion component 21.8, polar component 51.0) and diiodomethane (non-polar liquid, surface energy γ L =50.8mN / m, dispersion component 50.8, polar component 0) The contact angles (θ1, θ2) of the two liquids on the PP surface are calculated using the following formula to obtain the surface energy;

[0070] First use the following formula:

[0071]

[0072] where γL is the total surface energy of the liquid (known); is the dispersion of the liquid (known); is the polar component (known); θ is the contact angle of the liquid on the solid surface (measured value); is the solid surface energy component to be determined;

[0073] Finally, use the OWRK formula: Calculate the corresponding modified PP surface energy;

[0074] (4) Peel strength: The test was conducted according to ASTM D903. The modified PP sheet (100 mm × 25 mm × 2 mm) was bonded to an aluminum substrate (anodized) with epoxy adhesive (3M DP460). The curing conditions were: 25°C / 24 h. The peel strength was measured using a universal material testing machine at a 180° peeling speed of 100 mm / min. The average value of 5 tests was taken. The force per unit width required to separate the adhesive from the substrate was used to reflect the bonding performance.

[0075] (5) Spray adhesion: Tested according to ASTM D3359. Spray polyurethane topcoat (PPGD8002) on the PP surface with a dry film thickness of 30±5μm and cure at 80℃ for 20min. Use a six-blade cutter (blade spacing 1mm) to scratch a 10×10 grid, with the scratches deep into the substrate. Apply 3M 600 tape and quickly tear it off vertically. Rating is based on the coating peeling area (0B-5B, 5B is the best).

[0076] (6) Melt flow index (MFI): tested according to ASTM D1238, temperature: 230°C (PP standard test temperature); load: 2.16 kg; preheat for 5 min, cut the melt outflow, weigh the cut weight 5 times and take the average value, and calculate the 10 min flow rate. Specific embodiments

[0078] Example 1

[0079] Using twin screw extruder (model: ZSK 70Mc 18 , purchased from Coperion (Nanjing) Machinery Co., Ltd.), and PP material was prepared by the following steps:

[0080] 1. Raw material pretreatment:

[0081] PP resin drying: Place the homopolymer PP pellets in a vacuum drying oven (80°C, -0.095 MPa) and dry them for 4 hours to remove moisture (target moisture content ≤ 0.02%).

[0082] Nanofiller pretreatment: Amination of SiO2 was performed by adding silane coupling agent KH550 (filler: KH550 = 10:1) and anhydrous ethanol, ultrasonically treated for 30 minutes (500W, 20kHz), and vacuum dried at 80°C for 4 hours.

[0083] 2. Premix

[0084] Matrix resin mixing: Add 82 parts of dried PP, 6 parts of POE-g-MAH, and 4 parts of EVA into a high-speed mixer and mix at room temperature for 5 minutes (speed 800 rpm);

[0085] Initiator pre-dispersion: 0.08 parts of DCP and 0.5 parts of dynamic crosslinker (lipoic acid-polycaprolactone copolymer) were premixed using a microfeeder to form a masterbatch.

[0086] 3. Main feeding

[0087] Main material delivery: The pre-mixed PP / POE-g-MAH / EVA mixture is fed into the main feeding port of the twin-screw extruder (feeding rate 50kg / h) through a loss-in-weight feeder (accuracy ±0.2%);

[0088] Dynamic cross-linking agent addition: lipoic acid derivative masterbatch was quantitatively added (rate 0.5 kg / h) through a side feeder (position L / D=25).

[0089] 4. Melt plasticization

[0090] Melting section temperature control: twin screw zone 1-2 temperature is set at 170-180°C, screw speed is 250rpm, so that PP is completely melted (melt temperature 180-185°C);

[0091] Initial dispersion: The compatibilizer (POE-g-MAH) and the base resin are initially dispersed through 45° staggered kneading blocks (L / D=10-15).

[0092] 5. Grafting reaction

[0093] Monomer injection: In zone 3 of the twin-screw extruder (L / D = 20), a mixture of 2.0 parts of MAH, 1.0 parts of GMA, and 0.6 parts of HEA was injected into the melt via a liquid injection pump;

[0094] Initiator activation: DCP decomposes at 190-200°C (zone 3-4), initiating a free radical grafting reaction (residence time 50 seconds).

[0095] 6. Dynamic Crosslinking

[0096] Low-temperature reorganization: When the melt enters zone 5-6 (170-175°C), lipoic acid derivatives dynamically reorganize through disulfide bonds (-SS-) to form a reversible cross-linking network;

[0097] Shear control: shear rate 1200-1500s applied by toothed disc element (L / D=30-32) -1 , promoting uniform distribution of the crosslinker.

[0098] 7. Nanofiller injection

[0099] Preparation of suspension: 2.5 parts of pretreated nanofiller (SiO2) were mixed with ethanol (solid content 10%) to form a stable suspension;

[0100] High-pressure injection: In zone 6 of the twin-screw extruder (L / D=35), the suspension is injected into the melt through a high-pressure gear pump (pressure 0.8 MPa), and the ethanol evaporates immediately.

[0101] 8. Extrusion granulation and pelletizing

[0102] The melt was extruded through a die at 175°C, and the extruded strands were cooled by passing through a water trough (water temperature 25°C). The pulling speed was 20m / min, and the rotary cutter (speed 1500rpm) cut the strands into 2-3mm particles, which were sieved (mesh size 20-40) to remove debris.

[0103] The segmented process parameters are as follows:

[0104]

[0105] Example 2

[0106] Example 2 was carried out according to the method described in Example 1. The difference from Example 1 was that no amino-silica nanofiller was added, and the types and contents of other raw materials in the formula remained consistent with those in Example 1.

[0107] Example 3

[0108] Example 3 was carried out according to the method described in Example 1. The difference from Example 1 was that the dynamic cross-linking agent lipoic acid derivative was not added, and the types and contents of other raw materials in the formula remained consistent with those in Example 1.

[0109] Example 4

[0110] Example 4 was carried out according to the method described in Example 1. The difference from Example 1 was that 2.0 parts of itaconic anhydride (ITA) was used instead of MAH on the basis of Example 1, and the types and contents of other raw materials in the formula remained consistent with those in Example 1.

[0111] Example 5

[0112] Example 5 was carried out according to the method described in Example 1. The difference from Example 1 was that 2.5 parts of montmorillonite (MMT) was used instead of amino silica on the basis of Example 1, wherein the montmorillonite was treated as follows before being injected into the PP melt: sodium pretreatment was performed by excess NaCl ion exchange, and then organic intercalation modification was performed with hexadecyltrimethylammonium bromide. The types and contents of other raw materials in the formula remained consistent with those in Example 1.

[0113] Example 6

[0114] Example 6 was carried out according to the method described in Example 1. The difference from Example 1 was that tetramethylthiourea (TMTD) was used instead of the lipoic acid derivative. The types and contents of other raw materials in the formula remained consistent with those in Example 1.

[0115] Example 7

[0116] Example 7 was carried out according to the method described in Example 1. The difference from Example 1 was that the distribution ratio of MAH:GMA:HEA was adjusted to 0.6:2:1 based on Example 1, and the types and contents of other raw materials in the formula remained consistent with Example 1.

[0117] Comparative Example 1

[0118] Comparative Example 1 was carried out according to the method described in Example 1, except that no amino-silica nanofiller and lipoic acid derivative were added, and only maleic anhydride was used as the grafting monomer.

[0119] Comparative Example 2

[0120] Comparative Example 2 was carried out according to the method described in Example 1, except that no grafting treatment was used and no lipoic acid derivative was added.

[0121] Comparative Example 3

[0122] Comparative Example 3 was carried out according to the method described in Example 1. The difference from Example 1 was that only MAH and GMA were used for grafting treatment, and the types and contents of other raw materials in the formula remained consistent with those in Example 1.

[0123] Comparative Example 4

[0124] Comparative Example 4 was carried out according to the method described in Example 1. The difference from Example 1 was that only MAH and HEA were used for grafting treatment, and the types and contents of other raw materials in the formula remained consistent with those in Example 1.

[0125] The formulation compositions and weights of the components of Examples 1-7 and Comparative Examples 1-4 are listed in Table 1 below:

[0126] Table 1 Composition ratio (parts by weight)

[0127]

[0128]

[0129] Note: *Itaconic anhydride; **Montmorillonite (MMT); ***Tetramethylthiourea (TMTD)

[0130] The materials prepared in Examples 1-7 and Comparative Examples 1-4 were tested and evaluated for their material properties. The test results are shown in Table 2.

[0131] Table 2 Test results

[0132]

[0133] The results in Table 2 demonstrate that, compared to traditional MAH grafting, the three-component grafting method disclosed herein significantly increases the surface energy of PP materials, from 33.0 mN / m (using traditional MAH grafting) to 50.3 mN / m, significantly enhancing the polarity of the PP material. Correspondingly, the peel strength increases from 3.5 N / cm to 11.2 N / cm, doubling the bond strength. Furthermore, the spray adhesion reaches Grade 5B according to ASTM D3359, compared to Grade 2B using traditional methods. Even with filler reinforcement, the material only achieves Grade 3B.

[0134] Compared with two-component grafting, the three-component grafting disclosed in the present invention increases the surface energy of the material from ≤39.2mN / m to 50.3mN / m, the peel strength from ≤5.5N / cm to 11.2N / cm, and the spray adhesion from ≤3B to 5B; it greatly improves the polarity of the material and has an unexpected synergistic effect.

[0135] The preparation method adopted in the present disclosure has processing stability and reduces energy consumption. The dynamic cross-linking technology keeps the melt flow index (MFI) at 15-20g / 10min, avoiding the degradation problem of the traditional grafting process, while the traditional process causes MFI <10g / 10min due to degradation; at the same time, the low-temperature cross-linking process (170-180°C) saves 15% energy compared with the traditional high-temperature grafting.

[0136] The PP material disclosed in the present invention can be directly sprayed without the need for corona, flame, primer and other treatment processes. The spray adhesion reaches 5B level, which is significantly improved compared to the traditional PP ≤2B level. The unit cost is reduced by 20-30%. It is suitable for the shells of auto parts, household appliances, etc. The spray-free yield rate of defects such as color difference and sagging is increased to 98%.

[0137] The above description is merely a preferred embodiment of the present disclosure and is not intended to limit the scope of the substantial technical content of the present disclosure. The substantial technical content of the present disclosure is broadly defined in the scope of the claims of the application. Any technical entity or method completed by others, if it is exactly the same as that defined in the scope of the claims of the application or is an equivalent variation, will be deemed to be included in the scope of the claims.

[0138] All documents mentioned in this disclosure are incorporated herein by reference, just as if each document were incorporated herein by reference individually. It should also be understood that after reading the above disclosure, those skilled in the art may make various changes or modifications to the disclosure, and that such equivalents also fall within the scope of the claims appended hereto.

Claims

1. A polypropylene modified material, comprising, based on the total weight of the polypropylene modified material, 70-90 wt% of a polypropylene base resin and 2-10 wt% of a multifunctional graft modifier, wherein the multifunctional graft modifier comprises a first monomer, a second monomer, and a third monomer, wherein the weight ratio of the first monomer, the second monomer, and the third monomer is (1-3):(0.5-1.5):(0.3-0.6), wherein the first monomer comprises an anhydride monomer, the second monomer comprises an epoxy group-containing acrylate monomer, and the third monomer comprises a hydroxyl group-containing acrylate monomer.

2. The polypropylene modified material according to claim 1, wherein The first monomer comprises at least one anhydride compound selected from maleic anhydride, itaconic anhydride, succinic anhydride, and malic anhydride; and / or The second monomer comprises at least one glycidyl ester monomer selected from glycidyl methacrylate and glycidyl acrylate; and / or The third monomer includes at least one monomer selected from hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

3. The polypropylene modified material according to claim 1, wherein The multifunctional graft modifier includes maleic anhydride monomer, glycidyl methacrylate monomer and hydroxyethyl acrylate monomer.

4. The polypropylene modified material according to claim 1, wherein The polypropylene matrix resin includes homopolypropylene, maleic anhydride grafted polyolefin elastomer and ethylene-vinyl acetate copolymer.

5. The polypropylene modified material according to any one of claims 1 to 4, characterized in that: The polypropylene modified material further comprises 1-3 wt% of a functionalized filler.

6. The polypropylene modified material according to claim 5, characterized in that: The functionalized filler comprises amino silica whose surface is modified by a silane coupling agent.

7. The polypropylene modified material according to claim 6, characterized in that: The polypropylene modified material further comprises 0.1-1 wt% of a dynamic crosslinking agent.

8. The polypropylene modified material according to claim 7, comprising:

9. A method for preparing the polypropylene modified material according to any one of claims 1 to 8, the method comprising: Step 1: Melting and plasticizing the polypropylene matrix resin; Step 2: injecting the multifunctional graft modifier into the molten polypropylene matrix resin to carry out a grafting reaction; Optional step 3: dynamically crosslinking the product obtained in step 2 under the action of a dynamic crosslinking agent; Optional step 4: injecting the functionalized filler into the product obtained in the previous step; The obtained product is extruded and granulated to obtain the polypropylene modified material.

10. A product prepared using the polypropylene modified material according to any one of claims 1 to 8.

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