CN113429670B

CN113429670B - Modified polypropylene composite material, preparation method thereof and surface coating method of composite material

Info

Publication number: CN113429670B
Application number: CN202110687614.1A
Authority: CN
Inventors: 范木良; 杨杰; 安峰; 申应军; 蒋士鹏; 张淼
Original assignee: Jinyoung Xiamen Advanced Materials Technology Co Ltd
Current assignee: Jinyoung Xiamen Advanced Materials Technology Co Ltd
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2023-04-07
Anticipated expiration: 2041-06-21
Also published as: CN113429670A

Abstract

The invention relates to the technical field of high polymer materials, in particular to a modified polypropylene composite material, a preparation method thereof and a surface coating method of the composite material. The modified polypropylene composite material at least comprises the following raw materials: polypropylene, paint-fixing additives and other additives; the paint spraying fastness assistant is polyamide resin powder modified by glycidyl methacrylate grafted polypropylene and subjected to annealing treatment. The modified polypropylene composite material obtained by adopting the technical scheme provided by the invention has the characteristics of good glossiness and firm paint spraying, can realize excellent paint spraying effect under the condition of flame-free treatment, has good comprehensive mechanical property, and can meet the requirement of a high-gloss polypropylene product on paint spraying fastness.

Description

Modified polypropylene composite material, preparation method thereof and surface coating method of composite material

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a modified polypropylene composite material, a preparation method thereof and a surface coating method of the composite material.

Background

The polypropylene is one of five types of general plastics with the largest output, has the characteristics of excellent mechanical property, chemical property, insulativity and the like, is widely applied to the fields of automobiles, household appliances, household building materials and the like, and becomes the fastest-developing variety in general resins. With the development of society, people have abundant requirements on product types and functions, for example, some products need high gloss to be beautiful as a whole, and need paint spraying treatment locally to achieve the effects of shading or adding identification patterns, and the like, so that the materials are required to have good sprayability to ensure that the paint fastness meets the actual use requirements. However, polypropylene is a non-polar material, the surface energy is low, most of the paint for spraying contains a polar solvent or an aqueous solvent, the paint is difficult to spread on the surface of polypropylene, and if the paint is directly sprayed on the polypropylene material, the coating is easy to fall off due to low adhesion and insufficient spraying fastness, so that the actual use function of the product is influenced. Therefore, the development of the modified polypropylene composite material with high gloss and excellent paint fastness is in actual demand.

For this purpose, some solutions have been proposed in the patent literature for lacquered polypropylene composites, as follows:

chinese patent application publication No. CN105367906A, whose publication date is 2016, 3, 2, discloses a flame-free polypropylene composite and a preparation method thereof, in which an ethylene-vinyl acetate copolymer is added to a raw material, and a molecular chain of the ethylene-vinyl acetate copolymer contains a vinyl acetate group, so that the polymer has a higher polarity, and the addition of the ethylene-vinyl acetate copolymer to a polypropylene material can improve the polarity of the polypropylene to achieve the purpose of direct spraying without flame treatment, but the ethylene-vinyl acetate copolymer has a large influence on the mechanical properties of the material and is high in cost, and the appearance gloss of the material cannot be considered.

Chinese patent application publication No. CN109486026A, whose publication date is 3/19/2019, discloses a polypropylene composition with improved surface flame treatment effect and a preparation method thereof, which can add styrene-based block copolymer, ethylene-propylene copolymer and filler to impart sprayability to the material, but the equipment cost of flame treatment is high, which increases the production cost, and there is a great risk due to open flame.

Disclosure of Invention

In order to solve the problem of insufficient sprayability of the polypropylene composite material mentioned in the background art, the invention provides a modified polypropylene composite material, which at least comprises the following raw materials: polypropylene, paint-fixing aids and other aids;

the paint spraying fastness assistant is polyamide resin powder modified by glycidyl methacrylate grafted polypropylene and subjected to annealing treatment.

In some embodiments, the weight ratio of the polypropylene to the paint fixative aid is (39.8-60.8): (4-25);

preferably, the weight ratio of the polypropylene to the paint-spraying fastness assistant is (47.8-56.8): (8 to 17).

In some embodiments, the raw materials of the composite material further include POE grafted glycidyl methacrylate, chlorinated polyolefin.

In some embodiments, the weight ratio of the polypropylene to the POE grafted glycidyl methacrylate is (39.8 to 60.8): (2-15);

preferably, the weight ratio of the polypropylene to the POE grafted glycidyl methacrylate is (39.8-57.8): (2-15);

preferably, the weight ratio of the polypropylene to the POE grafted glycidyl methacrylate is (47.8-56.8): (3-7);

in some embodiments, the weight ratio of the polypropylene to the chlorinated polyolefin is (39.8 to 60.8): (3-15);

preferably, the weight ratio of the polypropylene to the chlorinated polyolefin is (39.8-59.8): (3-15);

preferably, the weight ratio of the polypropylene to the chlorinated polyolefin is (47.8-56.8): 6.

in some embodiments, the chlorinated polyolefin is selected from at least one of chlorinated polyethylene, chlorinated polypropylene.

In some embodiments, the other auxiliary agent is one or more of a toughening agent, an antioxidant, a lubricant and a brightening dispersant.

In some embodiments, the weight ratio of the polypropylene to the toughening agent is (39.8 to 60.8): (2-10);

preferably, the weight ratio of the polypropylene to the toughening agent is (42.8-59.8): (2-10);

preferably, the weight ratio of the polypropylene to the toughening agent is (47.8-56.8): 5;

in some embodiments, the weight ratio of the polypropylene to the antioxidant is (39.8 to 60.8): (0.2 to 0.8);

preferably, the weight ratio of the polypropylene to the antioxidant is (47.4-57): (0.2 to 0.8);

preferably, the weight ratio of the polypropylene to the antioxidant is (47.8-56.8): 0.4;

in some embodiments, the weight ratio of the polypropylene to the lubricant is (39.8 to 60.8): (0.2 to 0.8);

preferably, the weight ratio of the polypropylene to the lubricant is (47.3-56.9): (0.2 to 0.8);

preferably, the weight ratio of the polypropylene to the lubricant is (47.8-56.8): 0.3;

in some embodiments, the weight ratio of the polypropylene to the shine dispersant is (39.8 to 60.8): (0.2 to 1);

preferably, the weight ratio of the polypropylene to the brightening dispersant is (47.3-57.1): (0.2 to 1);

preferably, the weight ratio of the polypropylene to the brightening dispersant is (47.8-56.8): 0.5.

in some embodiments, the raw material of the composite material further comprises a mineral filler, wherein the mineral filler is one or more of talcum powder, barium sulfate, calcium carbonate and wollastonite, and talcum powder and/or barium sulfate are preferably adopted.

In some embodiments, the weight ratio of the polypropylene to the talc is (39.8 to 60.8): (3-10);

preferably, the weight ratio of the polypropylene to the talcum powder is (42.8-58.8): (3-10);

preferably, the weight ratio of the polypropylene to the talcum powder is (47.8-56.8): 5;

in some embodiments, the weight ratio of the polypropylene to the barium sulfate is (39.8 to 60.8): (10-25);

preferably, the weight ratio of the polypropylene to the barium sulfate is (47.8-56.8): 15.

the invention provides a preparation method of a modified polypropylene composite material, which comprises the following steps:

mixing the raw materials, adding the mixture into an extruder, and performing melt granulation to obtain a modified polypropylene composite material;

the raw materials at least comprise polypropylene, a paint spraying fastness auxiliary agent and other auxiliary agents, wherein the paint spraying fastness auxiliary agent is polyamide modified by glycidyl methacrylate functionalized polypropylene and subjected to annealing treatment.

The invention provides a surface coating method of a modified polypropylene composite material, which comprises the following steps:

applying heat treatment at 100-140 ℃ to the part of the surface of the modified polypropylene composite material product needing coating treatment so as to form bulges on the surface of the modified polypropylene composite material product, wherein the time of the heat treatment is preferably 10-40 minutes;

coating the part of the surface with a coating;

the modified polypropylene composite material is prepared by adopting the modified polypropylene composite material or the preparation method of the modified polypropylene composite material.

Based on the above, compared with the prior art, the modified polypropylene composite material provided by the invention has excellent spraying performance by adding the modified polyamide resin powder modified by glycidyl methacrylate functionalized polypropylene and subjected to annealing treatment as a paint fastness assistant.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the embodiments of the present invention with reference to the technical solutions thereof, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; the technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, and should not be construed as limiting the present invention; it will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

(1) Weighing polypropylene, chlorinated polyethylene, a toughening agent, POE (polyolefin elastomer) grafted glycidyl methacrylate, a paint spraying fastness auxiliary agent, mineral filler, an antioxidant, a lubricant and a brightening dispersant according to parts by weight;

(2) Adding all the materials in the step (1) into a high-speed stirrer, and uniformly stirring and mixing at a high speed to obtain a premix, wherein the high-speed stirring speed is 120-400 r/min;

(3) Adding the premix obtained in the step (2) into a parallel double-screw extruder from a main feeding hopper, and shearing, melting, blending and extruding all raw material materials in the parallel double-screw extruder, wherein the processing temperature of the double-screw extruder is 170-190 ℃;

(4) And cooling, drying and granulating the material strips discharged from the neck mould of the parallel double-screw extruder to obtain the modified polypropylene composite material.

Wherein, in some embodiments, the modified polypropylene composite material comprises the following raw materials in parts by weight:

39.8-60.8 parts of polypropylene, 3-15 parts of chlorinated polyethylene, 2-10 parts of toughening agent, 2-15 parts of POE grafted glycidyl methacrylate, 4-25 parts of paint spraying fastness assistant, 13-35 parts of mineral filler, 0.2-0.8 part of antioxidant, 0.2-0.8 part of lubricant and 0.2-1 part of bright dispersant;

wherein, the mineral filler comprises 3 to 10 parts of talcum powder and 10 to 25 parts of barium sulfate.

In some preferred embodiments, the modified polypropylene composite material comprises the following raw materials in parts by weight:

47.8-56.8 parts of polypropylene, 6 parts of chlorinated polyethylene, 5 parts of a toughening agent, 3-7 parts of POE grafted glycidyl methacrylate, 8-17 parts of a paint spraying fastness assistant, 20 parts of a mineral filler, 0.4 part of an antioxidant, 0.3 part of a lubricant and 0.5 part of a bright dispersant;

wherein, in 20 parts of mineral filler, the mineral filler comprises 5 parts of talcum powder and 15 parts of barium sulfate.

As an alternative embodiment, the polypropylene is one or two combination of homo-polypropylene or co-polypropylene resin;

as an alternative embodiment, the chlorinated polyolefin is chlorinated polyethylene, preferably but not limited to santonin CPE2135, with a chlorine content of 35 ± 1%;

as an alternative embodiment, the toughening agent is preferably, but not limited to, korean SK ethylene propylene copolymer POE875L, with a melt index of 5g/10min;

the POE grafted glycidyl methacrylate is preferably but not limited to easy-to-use SOG-02, the content of the effective monomer of the glycidyl methacrylate is more than 1.0wt%, and the melt flow rate is 2-5 g/10min;

the preparation method of the paint fastness auxiliary agent comprises the following steps:

uniformly mixing polyamide and glycidyl methacrylate functional polypropylene according to the weight ratio of (85-96) to (4-15), freezing the mixture to the state of-100 to-150 ℃ by liquid nitrogen, keeping the state for 15-30 minutes, then grinding the mixture into powder by using a millstone type pulverizer, controlling the D50 particle diameter of the final powder mixture to be 230-890 micrometers by using a screen, preferably the D50 particle diameter to be 560 micrometers, then placing the powder mixture in a 130 ℃ oven, keeping the temperature for 20 minutes, annealing the powder mixture, preferably the annealing temperature to be 110-140 ℃, preferably the annealing time to be 10-40 minutes, cooling the material to the room temperature after the annealing treatment is finished, and packaging for later use to obtain the paint fastness assistant;

wherein, the glycidyl methacrylate functionalized polypropylene is preferably but not limited to SCONA TPPP 8104 FA produced by Bick chemical company, and the content of the glycidyl methacrylate is 2.5 percent; polyamides (commonly known as nylons) are thermoplastic resins containing recurring amide groups- [ NHCO ] -in the molecular backbone, including aliphatic polyamides, aliphatic-aromatic polyamides and aromatic polyamides, such as PA6, PA66, PA46, PA6T, PA9T, PA10T, PA12T, PPTA, etc., with melting points greater than 210 ℃, preferably but not limited to PA6J2400 nylon chips from Hangzhou Polycis;

as an alternative embodiment, the mineral filler includes talc, barium sulfate, and the like;

the talcum powder is preferably, but not limited to, superfine talcum powder HTP05L of IMIFABI (Italian method ratio) company, and the particle size of the talcum powder is 1 ten thousand meshes;

the barium sulfate is F-103 of Yunfo Hongzhi New Material Co., ltd, and the particle size of D50 is 0.1 micron.

As an alternative embodiment, the other adjuvants include, but are not limited to, tougheners, antioxidants, lubricants, brightening dispersants, and the like;

wherein, the antioxidant is preferably but not limited to one or more of hindered phenol antioxidant, thioester antioxidant and phosphite antioxidant.

The lubricant is preferably, but not limited to, one or more combinations of polyethylene wax, polypropylene wax, calcium stearate, zinc stearate, and magnesium stearate.

The brightening dispersant is preferably but not limited to YY-2012 produced by Guangzhou Yuitai synthetic materials Co., ltd, and is a polar group introduced on the basis of ethylene bis fatty acid amide, and due to the introduction of the group, the brightening dispersant has the characteristic of EBS and also has better dispersibility and brightening lubricity.

In this regard, the present invention provides specific examples as set forth in the following tables, see table 1;

table 1 table of the amount of each raw material used in the examples

In the above-described embodiments 1 to 4:

example 1

Weighing the corresponding raw materials in parts by weight, and referring to table 1;

wherein, PP140 powder is used as polypropylene A, PPBX3800 is used as polypropylene B, CPE2135 is used as chlorinated polyethylene, POE875L is used as a toughening agent, SOG-02 is used as POE grafted glycidyl methacrylate, the mineral filler comprises talcum powder and barium sulfate, HTP05L is used as the talcum powder, F-103 is used as the barium sulfate, 1010+168 is used as the talcum powder, CAST is used as a lubricating agent, and YY-2012 is used as a brightening agent;

the paint spraying fastness auxiliary agent is prepared by the following preparation method:

the polyamide and glycidyl methacrylate functionalized polypropylene are prepared by the following steps: 8, freezing the mixture to a state of-130 ℃ by liquid nitrogen and keeping the temperature for 20 minutes after uniformly mixing, then grinding the mixture into powder by using a millstone type grinder, controlling the D50 particle size of the final powder mixture to be 560 micrometers by using a screen, then placing the powder mixture into an oven at 130 ℃ and keeping the temperature for 20 minutes, annealing the powder mixture, wherein the annealing temperature is 130 ℃, the time is 20 minutes, and after the annealing treatment is finished, cooling the material to room temperature and packaging for later use to obtain the paint fastness auxiliary agent.

Uniformly mixing polypropylene A, polypropylene B, chlorinated polyethylene, a toughening agent, POE grafted glycidyl methacrylate, a spray paint fastness auxiliary agent, talcum powder, barium sulfate, an antioxidant, a lubricant and a bright dispersing agent, and adding the mixture into a parallel double-screw extruder from a main feeding port to enable all raw materials to be subjected to shearing, melting, blending and extruding in the parallel double-screw extruder, wherein the processing temperature of the double-screw extruder is 170 ℃ in a first zone, 180 ℃ in a second zone, 190 ℃ in a third zone, 190 ℃ in a fourth zone, 190 ℃ in a fifth zone, 180 ℃ in a sixth zone, 180 ℃ in a seventh zone, 180 ℃ in an eighth zone, 180 ℃ in a ninth zone, 180 ℃ in a tenth zone and 190 ℃ in a machine head;

and finally, cooling, drying and granulating the material strips discharged from the neck mould of the parallel double-screw extruder to obtain the modified polypropylene composite material.

Example 2

The corresponding raw materials are weighed according to the parts by weight, and the preparation method is the same as that of the example 1 with reference to the table 1.

Example 3

Example 4

The corresponding raw materials are weighed according to the parts by weight, and the preparation method is the same as that of the example 1 with reference to the table 1. In addition, the present invention provides specific comparative experiments as set forth in the following table, see table 2;

table 2 table of each raw material usage of comparative examples

In comparative examples 1 to 5:

comparative example 1

The corresponding raw materials are weighed according to the parts by weight, and the preparation method is the same as that of the example 1 with reference to the table 2.

Comparative example 2

Comparative example 3

The corresponding raw materials were weighed out in the parts by weight as described above, see table 2, the preparation method is the same as in example 1, and the difference between this comparative experiment and example 4 is that the D50 particle size of the paint fastness aid in the milling stage was controlled at 900 μm.

Comparative example 4

The raw materials were weighed out in the above-mentioned proportions by weight, see table 2, and the preparation method was the same as in example 1, but the difference between this comparative experiment and example 4 was that the D50 particle size of the paint fastness aid in the milling stage was controlled to 200 μm.

Comparative example 5

The corresponding raw materials are weighed according to the parts by weight, see table 2, the preparation method is the same as that of example 1, and the difference of the comparative experiment from example 4 is that the paint fastness auxiliary agent is prepared without adding glycidyl methacrylate functionalized polypropylene.

It should be noted that the specific parameters or some common reagents in the above embodiments are specific examples or preferred embodiments of the present invention, and are not limited thereto; those skilled in the art can adapt the same within the spirit and scope of the present invention.

The composite materials obtained in the above examples and comparative examples were tested as follows: tensile strength, notched izod impact strength, unannealed gloss, post-annealed gloss, and a hundred grid test ISO rating.

Wherein:

tensile property: according to ISO 527-2 standard, the size of a sample is 170 multiplied by 10 multiplied by 4mm, and the temperature of the sample is set to be 180 ℃ in the injection molding process;

izod notched impact performance: according to ISO 180 standard, the size of a sample is 80 multiplied by 10 multiplied by 4mm, and the temperature of the sample is set to be 180 ℃ in the injection molding process;

unannealed gloss: the prepared material is used for injection molding of a highlight sample plate, the temperature of the sample plate is set to 180 ℃ in the injection molding process, and then the gloss test is carried out according to the GB/T8807-1988 standard, and the size of the sample plate is 300 multiplied by 100 multiplied by 5mm;

gloss after annealing: the prepared material is used for injection molding of a highlight sample plate, the temperature of the sample plate is set to be 180 ℃ in the injection molding process, then the color plate is placed in a 120 ℃ oven and kept for 20 minutes, the sample plate is annealed, then the gloss test is carried out according to the GB/T8807-1988, and the size of the sample plate is 300 multiplied by 100 multiplied by 5mm;

and (3) testing the grids: according to the GB/T9286 standard, 10 × 10 small grids are scribed on the surface of a test sample wafer by using a hundred-grid knife, the scribing length is about 20MM, the depth is suitable for scratching a paint layer, paint layer powder or filaments at the scribing edge are cleaned by using a brush, a 3M adhesive tape (the model is 610 #) with the length of about 75MM is prepared, one end of the 3M adhesive tape is slowly and flatly attached to the hundred grids from the edge of the hundred grids, then the adhesive tape is lightly pressed by fingers to ensure that no residual air bubbles exist between the adhesive tape and the sample wafer, after flattening, the 3M adhesive tape is waited for 90 +/-30 seconds, then the sample wafer is pressed by the left hand, the free end of the adhesive tape is pinched by the right hand, the 3M adhesive tape is rapidly torn off at about 180 degrees in the opposite direction, the test is repeated for 2 times at other plane parts of the sample wafer, and a magnifier is used for carefully checking the falling-off condition of the coating on the hundred grids. Grading the hundred-grid test:

ISO rating of 0-the edges of the cut are completely smooth, without any flaking at the edges of the grid;

ISO rating of 1-there was a small piece peeling at the intersection of the cuts, with no more than 5% actual breakage in the scribed area.

ISO class 2-the edge and/or intersection of the cut is peeled off, with an area greater than 5% but less than 15%.

ISO rating 3-partial or full peel along the edge of the cut and/or partial cells are peeled off in one piece. The area peeled off was more than 15% but less than 35%.

ISO grade 4-the cut edge is peeled off in large pieces and/or some squares are partially or completely peeled off, and the area of the cut edge is more than 35 percent of the area of the ruled area but not more than 65 percent.

ISO rating of 5-over the last rating.

The results of testing the materials obtained in the examples and comparative examples are shown in the following table:

TABLE 3 table of performance test of each example and comparative example

From the above examples, comparative examples and their data of performance test results, i.e., tables 1, 2, 3, it can be seen that:

as can be seen from the comparison between the example 1 and the example 2, as the proportion of the POE grafted glycidyl methacrylate SOG-02 component is increased, the epoxy group on the glycidyl methacrylate molecular chain and the amino group or the carboxyl group on the nylon molecular chain are subjected to chemical reaction, and the SOG-02 can be used as a transition layer, so that the compatibility between the nylon 6 resin in the paint spraying fastness assistant 560 and the POE component in the composite material is better, the bonding force between the two components is stronger, and the overall mechanical property of the composite material is better;

as can be seen from the comparison between the example 1 and the example 3, as the proportion of the paint fastness assistant 560 is increased, the concave-convex points formed on the surface of the product after annealing treatment are increased, the roughness of the surface of the product and the contact area between the coating and the product are increased, the adhesion of coating substances is facilitated during the spraying treatment, and the fastness of the coating is improved; meanwhile, as the nylon is a polar material and the coating is also a polar material, the nylon 6 resin powder exposed on the surface of the product has better affinity to the coating, increases the contact active points between the coating and the substrate, and can further improve the fastness of the coating;

as can be seen from the comparison between the comparative example 1 and the example 4, the POE grafted glycidyl methacrylate SOG-02 component is not added, the compatibility of the paint spraying fastness auxiliary 560 and the POE component in the composite material is insufficient, and the overall mechanical property of the composite material is low;

as can be seen from the comparison between the comparative example 2 and the example 4, the paint fastness assistant 560 is not added, concave-convex points and active points contacted between the coating and the base material cannot be formed on the surface of the product after annealing treatment, the adhesion of the coating is poor, and the fastness of the coating is low;

as can be seen from the comparison between the comparative example 3 and the example 4, when the particle size of the paint spraying fastness assistant D50 is 900 microns, the paint spraying fastness assistant with a coarse particle size has a large influence on the appearance glossiness of a molded product and has a low surface glossiness because the main component of the paint spraying fastness assistant is modified nylon 6 powder which has a high melting point and is not melted in the molding process of a composite material;

as can be seen from the comparison between the comparative example 4 and the example 4, when the particle size of the paint fastness assistant D50 is 200 microns, the particle size is too small and is influenced by instant shear heat generated by high-speed rotation friction of the screw in the twin-screw granulation process, the particle size of the paint fastness assistant is further reduced, so that a product cannot form better concave-convex points after annealing, the exposure degree of nylon 6 powder particles in the paint fastness assistant on the surface of the product is insufficient, a coating is not favorably attached to the surface of the product during paint spraying, and the coating fastness is lower;

as can be seen from the comparison between the comparative example 5 and the example 4, the paint-spraying fastness auxiliary agent is prepared without adding the glycidyl methacrylate functionalized polypropylene SCONA TPPP 8104 FA, the compatibility of the paint-spraying fastness auxiliary agent and the polypropylene component in the composite material is insufficient, and the overall mechanical property of the composite material is low.

In some embodiments, for some product parts which need high gloss in overall appearance and need to be sprayed locally, modified polyamide resin (such as nylon 6, nylon 66 and the like) powder which is modified by glycidyl methacrylate functionalized polypropylene and is subjected to annealing treatment and has a selected particle size is used as the paint-spraying fastness assistant modified polypropylene composite material, and during injection molding, because the injection molding temperature is set only at the melting temperature of PP (polypropylene), which is far lower than the melting temperature of the polyamide resin (such as nylon 6, nylon 66 and the like) powder in the paint-spraying fastness assistant, the PP material melt has good fluidity, and is positioned at the front end of the melt during injection molding and firstly contacts with the inner surface of a mold, namely the outer surface of the product is covered by the PP material, the product has high appearance gloss, and the product obtains a good appearance effect;

and the polyamide resin (such as nylon 6, nylon 66 and the like) powder which is not melted in the injection and mold filling process is uniformly dispersed and distributed in the PP melt in a solid particle state, most of the polyamide resin (such as nylon 6, nylon 66 and the like) powder is coated by the PP material melt, namely the molded polyamide resin (such as nylon 6, nylon 66 and the like) powder is positioned in the product, and the highlight property of the product appearance is not influenced, even if very few parts of the polyamide resin (such as nylon 6, nylon 66 and the like) powder which is not coated by the PP material melt are in a state that the surface layer of the polyamide resin (such as nylon 6, nylon 66 and the like) powder particle is softened to a certain degree or even slightly melted due to instant high-temperature heat generated by double-screw rotating friction shearing in the double-screw extrusion and granulation process, so that the surface gloss of the final product is not influenced during mold filling.

For the part of the modified polypropylene composite material product provided by the invention which needs to be locally sprayed, heat treatment is applied to the part of the product at 110-140 ℃ for 10-40 minutes (the part which does not need to be sprayed is covered by heat insulation cotton for heat insulation), and the annealing process further improves the crystallinity of the polypropylene material on the surface of the part, increases the density and shrinks the volume inwards; whereas the polyamide resin (for example nylon 6, nylon 66, etc.) powder particles of the paint fastness aid uniformly distributed within the composite material are due to: (1) not receiving sufficient heat inside the material; (2) The heat resistance of polyamide resin (such as nylon 6, nylon 66, etc.) powder is higher than that of polypropylene material, and the annealing temperature is higher; (3) The 3-fold factor that polyamide resin (e.g., nylon 6, nylon 66, etc.) powder has been annealed in advance and is difficult to crystallize any further is such that the paint fastness aid does not shrink by further crystallization.

Therefore, the polypropylene material on the surface layer shrinks inwards, and the paint spraying fastness auxiliary agent inside does not shrink, so that the paint spraying fastness auxiliary agent forms a slight bulge on the surface of the product, the surface of the product has certain roughness and excess, the contact area between the coating and the product is increased, the adhesion of the coating substance is facilitated during the spraying treatment, and the coating fastness is improved.

On the other hand, because the polyamide resin (such as nylon 6, nylon 66 and the like) powder in the paint fastness assistant is a polar material, and the coating is also a polar material, the polyamide resin (such as nylon 6, nylon 66 and the like) powder exposed on the surface of the product has better affinity for the coating, the active contact points between the coating and the substrate are increased, and the coating fastness can be further improved.

Meanwhile, in the preparation process of the paint spraying fastness assistant, the polypropylene SCONA TPPP 8104 FA functionalized by glycidyl methacrylate is ground together with polyamide resin (such as nylon 6, nylon 66 and the like) slices to prepare powder, and in the grinding process and the high-temperature annealing process, the glycidyl methacrylate functionalized polypropylene (such as SCONA TPPP 8104 FA) can be used as a transition layer by virtue of the strong friction between materials and the chemical reaction between amino or carboxyl on a polyamide resin molecular chain and an epoxy group on the glycidyl methacrylate molecular chain, and a polypropylene phase and a polyamide phase are linked in the composite material, so that the bonding force between the two components in the material is increased, and the integral mechanical property of the composite material is improved.

In addition, a POE grafted glycidyl methacrylate (SOG-02) component is added in the double-screw granulation process, so that the compatibility of the polyamide resin in the paint fastness auxiliary agent and a toughening agent POE component in the composite material is improved, the binding force between the two components is improved, and the overall mechanical property of the composite material is further improved.

In conclusion, compared with the prior art, the modified polypropylene composite material prepared by adopting the technical scheme of the invention has the characteristics of good comprehensive mechanical property, high glossiness and excellent paint fastness, and can meet the requirement of a high-glossiness polypropylene product on the paint fastness.

In addition, it will be appreciated by those skilled in the art that, although there may be many problems with the prior art, each embodiment or aspect of the present invention may be improved only in one or several respects, without necessarily simultaneously solving all the technical problems listed in the prior art or in the background. It will be understood by those skilled in the art that nothing in a claim should be taken as a limitation on that claim.

Although terms such as polypropylene, polyamide, grafting, modifying etc. are used more often herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention; the terms "first," "second," and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The modified polypropylene composite material is characterized by at least comprising the following raw materials: polypropylene, POE (polyolefin elastomer) grafted glycidyl methacrylate, a paint-spraying fastness assistant and other assistants;

the paint-spraying fixing auxiliary agent is polyamide resin powder modified by glycidyl methacrylate grafted polypropylene and subjected to annealing treatment, and the particle size of D50 of the paint-spraying fixing auxiliary agent is 230-890 micrometers.

2. The modified polypropylene composite material as claimed in claim 1, wherein the weight ratio of the polypropylene to the paint-proofing assistant is (39.8-60.8): (4-25).

3. The modified polypropylene composite of claim 1, wherein the raw materials of the composite further comprise a chlorinated polyolefin.

4. The modified polypropylene composite material of claim 3, wherein the weight ratio of the polypropylene to the POE grafted glycidyl methacrylate is (39.8-60.8): (2-15); the weight ratio of the polypropylene to the chlorinated polyolefin is (39.8-60.8): (3-15).

5. The modified polypropylene composite according to claim 1, wherein: the other auxiliary agents are one or more of a toughening agent, an antioxidant, a lubricant and a brightening dispersant.

6. The modified polypropylene composite of claim 5, wherein: the weight ratio of the polypropylene to the toughening agent is (39.8-60.8): (2-10); the weight ratio of the polypropylene to the antioxidant is (39.8-60.8): (0.2-0.8); the weight ratio of the polypropylene to the lubricant is (39.8-60.8): (0.2 to 0.8); the weight ratio of the polypropylene to the brightening dispersant is (39.8-60.8): (0.2-1).

7. The modified polypropylene composite according to claim 1, wherein: the raw materials of the composite material also comprise mineral filler, wherein the mineral filler is one or more of talcum powder, barium sulfate, calcium carbonate and wollastonite.

8. The modified polypropylene composite of claim 7, wherein: the weight ratio of the polypropylene to the talcum powder is (39.8-60.8): (3-10); the weight ratio of the polypropylene to the barium sulfate is (39.8-60.8): (10 to 25).

9. The preparation method of the modified polypropylene composite material is characterized by comprising the following steps:

the raw materials at least comprise polypropylene, POE (polyolefin elastomer) grafted glycidyl methacrylate, a paint-spraying fixing auxiliary and other auxiliary agents, the paint-spraying fixing auxiliary is polyamide modified by glycidyl methacrylate functionalized polypropylene and subjected to annealing treatment, and the D50 particle size of the paint-spraying fixing auxiliary is 230-890 micrometers.

10. A method for coating a surface coating of a modified polypropylene composite material is characterized by comprising the following steps:

applying heat treatment at 100-140 ℃ to the part of the surface of the modified polypropylene composite material product needing coating treatment so as to form a bulge on the surface of the modified polypropylene composite material product;

coating the part of the surface with a coating;

wherein the modified polypropylene composite material is the modified polypropylene composite material as defined in any one of claims 1 to 8, or the modified polypropylene composite material prepared by the preparation method of the modified polypropylene composite material as defined in claim 9.