阅读说明：本技术 一种多层包覆共挤型材及其生产方法 (Multilayer coating co-extrusion profile and production method thereof ) 是由 唐道远 于 2021-08-05 设计创作，主要内容包括：本发明提供了一种多层包覆共挤型材及其生产方法,该共挤型材包括刚性芯和共挤包覆在所述刚性芯外周的包覆层,所述包覆层包括内包覆层和外包覆层,所述的内包覆层由聚烯烃、不饱和羧酸改性聚烯烃和植物纤维粉为主要成分的聚烯烃木塑物料制得；所述外包覆层由热塑性弹性体、热塑性工程塑料、离子聚合树脂、离子聚合树脂强化的聚烯烃塑料的其中一种制成；所述的刚性芯和所述的内包覆层之间还具有第一胶黏剂层；所述第一胶粘剂层选用的胶为不饱和羧酸改性聚烯烃热熔胶或聚氨酯热熔胶。通过多层结构的设置使型材同时具有芯材的物理强度、木塑层的仿木效果以及耐腐蚀性和共挤表层的耐磨性能。(The invention provides a multi-layer coating co-extrusion section bar and a production method thereof, the co-extrusion section bar comprises a rigid core and a coating layer which is coated on the periphery of the rigid core in a co-extrusion way, the coating layer comprises an inner coating layer and an outer coating layer, and the inner coating layer is prepared from polyolefin wood-plastic materials which take polyolefin, unsaturated carboxylic acid modified polyolefin and plant fiber powder as main components; the outer cladding layer is made of one of thermoplastic elastomer, thermoplastic engineering plastic, ionic polymer resin and polyolefin plastic reinforced by the ionic polymer resin; a first adhesive layer is arranged between the rigid core and the inner cladding layer; the adhesive selected for the first adhesive layer is unsaturated carboxylic acid modified polyolefin hot melt adhesive or polyurethane hot melt adhesive. The profile has the physical strength of the core material, the wood-like effect and the corrosion resistance of the wood-plastic layer and the wear resistance of the co-extrusion surface layer simultaneously through the arrangement of the multilayer structure.)

1. The utility model provides a multilayer cladding coextrusion section bar, includes rigid core and crowded cladding altogether the cladding in rigid core periphery, its characterized in that: the coating layer comprises an inner coating layer and an outer coating layer, wherein the inner coating layer is prepared from polyolefin wood-plastic materials taking polyolefin, unsaturated carboxylic acid modified polyolefin and plant fiber powder as main components; the outer cladding layer is made of one of thermoplastic elastomer, thermoplastic engineering plastic, ionic polymer resin and polyolefin plastic reinforced by the ionic polymer resin; a first adhesive layer is arranged between the rigid core and the inner cladding layer; the adhesive selected for the first adhesive layer is unsaturated carboxylic acid modified polyolefin hot melt adhesive or polyurethane hot melt adhesive.

2. A multi-layer clad co-extrusion profile according to claim 1, wherein: a second adhesive layer is arranged between the inner cladding layer and the outer cladding layer; the adhesive selected by the second adhesive layer is unsaturated carboxylic acid modified polyolefin hot melt adhesive or polyurethane hot melt adhesive.

3. A multi-layer clad co-extrusion profile according to claim 1, wherein: the rigid core is an aluminum alloy section, the first adhesive layer is a polyurethane hot melt adhesive, and the second adhesive layer is a maleic acid grafted modified polyethylene hot melt adhesive.

4. A method for producing a multi-layer clad co-extruded profile comprises the following steps:

s1, providing a rigid core material;

s2, guiding the rigid core material into a core material channel of the co-extrusion die; meanwhile, a first adhesive is melted and extruded through a first extruder and enters a first adhesive runner of a co-extrusion die, so that the first adhesive is coated on the periphery of the rigid core material to form a glue-coated core material; then, the polyolefin wood-plastic material is melted and plasticized by a second extruder and then extruded into an intermediate layer runner of a co-extrusion die, so that the polyolefin wood-plastic material coats the glue-coated core material to form an intermediate layer, and a first coated core material is obtained; then, a second adhesive is melted and extruded through a third extruder and enters a second adhesive runner of a co-extrusion die, so that the second adhesive is coated on the periphery of the first coating core material to form a second coating core material; then, extruding the surface material into a surface runner of a co-extrusion die after the surface material is melted and plasticized by a fourth extruder, so that the surface material coats the second rubber-coated core material to form a co-extrusion surface layer, thereby obtaining a second coated core material;

s3, after being led out from a die orifice of the co-extrusion die, the second coating core material is naturally cooled or cooled by water to form a multi-layer coating co-extrusion section;

the first adhesive layer and the second adhesive layer are both composed of unsaturated carboxylic acid modified polyolefin hot melt adhesive or polyurethane hot melt adhesive;

the surface material is selected from one of thermoplastic engineering plastics, thermoplastic elastomers, ionic polymer resin or ionic polymer resin reinforced polyolefin plastics.

5. A method of producing a multi-layer clad co-extruded profile as claimed in claim 4, wherein: the rigid core is an aluminum alloy section, and the aluminum alloy section is subjected to preheating treatment before being introduced into a core material channel of the co-extrusion die; the first adhesive layer is a polyurethane hot melt adhesive, and the second adhesive layer is a maleic acid grafted modified polyethylene hot melt adhesive.

6. The production method of the multi-layer cladding coextrusion section bar according to claim 4, wherein the polyolefin wood-plastic material comprises the following components in parts by mass: 10-20 parts of polyethylene, 15-25 parts of maleic anhydride grafted polyethylene, 30-50 parts of plant fiber powder and 10-20 parts of filler.

7. A method of producing a multi-layer clad co-extruded profile as claimed in claim 4, wherein: in the ionic polymerization resin reinforced polyolefin plastic, the mass part of the ethylene- (methyl) acrylate is 20-30, and the mass part of the polyethylene is not less than 60.

8. A method of producing a multi-layer clad co-extrusion profile as claimed in claim 7, wherein: the polyolefin plastic reinforced by the ionic polymerization resin also comprises an antioxidant, a light stabilizer and an ultraviolet absorber.

9. A method of producing a multi-layer clad co-extruded profile as claimed in claim 4, wherein: the rigid core is a metal core material or a high-temperature-resistant glass fiber reinforced plastic core material.

10. A method of producing a multi-layer clad co-extrusion profile as claimed in claim 9, wherein: a groove is formed on the surface of the aluminum alloy core material along the length direction of the metal core material, and the depth of the groove is 0.3-1.0 mm; the thickness of the first adhesive layer is 0.5-2.0 mm.

Technical Field

The invention relates to a multi-layer coating co-extrusion section bar and a production method thereof, belonging to the technical field of composite section bars.

Background

In recent years, with the development of the wood-plastic industry, some schemes for producing the section bar by adopting wood-plastic materials are proposed. Because the problem of insufficient physical strength often appears in pure wood-plastic section bars, in some occasions, especially in outdoor occasions where the section bars need to be laid in an overhead manner, the bearing capacity of the section bars is limited, so people usually adopt the wood-plastic clad section bars to meet the actual use requirements, namely, the material with higher physical strength is selected as a core material, and the periphery of the core material is clad with the wood-plastic material, thereby obtaining the section bars with high physical strength and wood-like effect. For example, the patent document with the application number of CN201711448420.6 provides a three-layer co-extrusion process of PE, hot melt adhesive and aluminum alloy, in which the aluminum alloy is used as a core material, and a PE wood-plastic layer is coated outside the aluminum alloy core material through the hot melt adhesive, so as to obtain a composite section with wood-like appearance and metal strength. However, the scheme still has certain defects, when the common wood-plastic material is directly exposed outside as a coating layer, the problems of insufficient wear resistance and scratch resistance or lack of surface layer elasticity exist, the surface is easily abraded after long-term use, the aesthetic degree is influenced, and the abrasion of the wood-plastic material is further aggravated after the abrasion is formed. In the prior art, the surface of the wood-plastic material is usually reinforced by adopting the photocureable coating or the wear-resistant paster of aluminum oxide, so that the wear resistance of the wood-plastic material is improved, but the laminating process of the photocureable coating and the wear-resistant paster and the co-extrusion molding operation of the wood-plastic clad plate are difficult to be carried out continuously, so that the process flow is complicated, and the production efficiency is influenced.

Disclosure of Invention

The invention provides a production method of a multilayer coating co-extrusion section, which obtains an integrally formed multilayer coating section in an extrusion forming mode. The section bar comprises a core material, an adhesive layer, a wood-plastic layer and a co-extrusion surface layer from inside to outside in sequence, and the section bar is enabled to have the physical strength of the core material, the wood-plastic imitation effect of the wood-plastic layer, the corrosion resistance and the wear resistance of the co-extrusion surface layer through the arrangement of the multilayer structure. Compared with the conventional wear-resistant layer processing method, the method has the advantages of simpler process flow and higher production efficiency.

Specifically, the invention adopts the following technical scheme:

a multi-layer coated co-extrusion section comprises a rigid core and a coating layer coated on the periphery of the rigid core in a co-extrusion manner, wherein the coating layer comprises an inner coating layer and an outer coating layer, and the inner coating layer is made of polyolefin wood-plastic materials taking polyolefin, unsaturated carboxylic acid modified polyolefin and plant fiber powder as main components; the outer cladding layer is made of one of thermoplastic elastomer, thermoplastic engineering plastic, ionic polymer resin and polyolefin plastic reinforced by the ionic polymer resin; a first adhesive layer is arranged between the rigid core and the inner cladding layer; the adhesive selected for the first adhesive layer is unsaturated carboxylic acid modified polyolefin hot melt adhesive or polyurethane hot melt adhesive.

Preferably, a second adhesive layer is arranged between the inner cladding layer and the outer cladding layer; the adhesive selected by the second adhesive layer is unsaturated carboxylic acid modified polyolefin hot melt adhesive or polyurethane hot melt adhesive.

Preferably, in the technical scheme, the rigid core is an aluminum alloy profile, the first adhesive layer is a polyurethane hot melt adhesive, and the second adhesive layer is a maleic acid grafted modified polyethylene hot melt adhesive.

It is another object of the present invention to provide a method for producing a multilayer clad co-extruded profile.

A method for producing a multi-layer clad co-extruded profile comprises the following steps:

s1, providing a rigid core material;

s2, guiding the rigid core material into a core material channel of the co-extrusion die; meanwhile, a first adhesive is melted and extruded through a first extruder and enters a first adhesive runner of a co-extrusion die, so that the first adhesive is coated on the periphery of the rigid core material to form a glue-coated core material; then, the polyolefin wood-plastic material is melted and plasticized by a second extruder and then extruded into an intermediate layer runner of a co-extrusion die, so that the polyolefin wood-plastic material coats the glue-coated core material to form an intermediate layer, and a first coated core material is obtained; then, a second adhesive is melted and extruded through a third extruder and enters a second adhesive runner of a co-extrusion die, so that the second adhesive is coated on the periphery of the first coating core material to form a second coating core material; then, extruding the surface material into a surface runner of a co-extrusion die after the surface material is melted and plasticized by a fourth extruder, so that the surface material coats the second rubber-coated core material to form a co-extrusion surface layer, thereby obtaining a second coated core material;

s3, after being led out from a die orifice of the co-extrusion die, the second coating core material is naturally cooled or cooled by water to form a multi-layer coating co-extrusion section;

the first adhesive layer and the second adhesive layer are both composed of unsaturated carboxylic acid modified polyolefin hot melt adhesive or polyurethane hot melt adhesive;

the surface material is selected from one of thermoplastic engineering plastics, thermoplastic elastomers, ionic polymer resin or ionic polymer resin reinforced polyolefin plastics.

The rigid core material is generally preheated before being introduced into the co-extrusion die, so as to avoid the situation that the hot melt is rapidly cooled when being extruded to the surface of the core material with low temperature, and the bonding of the core material and the core material is affected. The preheating is usually realized by a tunnel type oven at a constant speed, and the heat source of the oven can be infrared irradiation or electric heating.

The core material enters the main runner along the feeding direction, and a first co-extrusion runner material outlet and a second co-extrusion runner material outlet are sequentially arranged in the moving direction of the core material, and are usually arranged on the upper wall and two side walls of the main runner. The first adhesive material is coated on the preheated core material, the polyolefin wood-plastic material is extruded from the first co-extrusion flow channel material outlet, the wood-plastic material is formed on the core material in a hot-melt state, the first adhesive material and the wood-plastic material are fused to a certain extent under the action of pressure, the first adhesive material and the wood-plastic material have certain compatibility, and the wood-plastic material is rapidly bonded with the core material through the first adhesive material. The position of the core material is taken as an example for explanation, in the process, the core material coated with the wood-plastic material is firstly coated with a layer of second adhesive material along with feeding, and then the second adhesive material enters a second co-extrusion runner material outlet after the second adhesive material advances by about 10-30 mm. The surface layer material is extruded from the second co-extrusion runner material outlet and then formed on the wood plastic material which is slightly solidified due to the advance of about 10-30 mm, and the surface layer material is still in a hot melting state due to the fact that the surface layer material is just extruded from the extruder and has good fluidity, so that the surface layer material can be rapidly coated on the slightly solidified wood plastic material and forms certain fusion with the wood plastic material under the action of pressure, and therefore the middle layer formed by the wood plastic material is coated.

The unsaturated carboxylic acid in the unsaturated carboxylic acid-modified polyolefin means a carboxylic acid or an anhydride or a carboxylic acid derivative having one or more unsaturated bonds, preferably, the unsaturated bond is a carbon-carbon double bond at the molecular terminal, for example: unsaturated monobasic acids such as acrylic acid, methacrylic acid and crotonic acid, dibasic acids such as maleic acid, maleic anhydride and phthalic acid, and derivatives of the above unsaturated carboxylic acids, for example, ester compounds formed by condensation of carboxylic acids and alcohols, and acyl compounds formed by substitution of hydroxyl groups of carboxylic acids. The side chain of the modified resin of the carboxylic acid and the derivatives thereof has oxygen-containing groups such as carbonyl, hydroxyl and the like, and the cellulose in the wood flour has a large amount of hydroxyl, so weak functional bonds such as hydrogen bonds and the like can be generated between the carboxylic acid and the derivatives thereof, and the carboxyl of the modified resin of the unsaturated carboxylic acid can be condensed with the hydroxyl in the cellulose to a certain extent to generate strong functional bonds, so the modified polyolefin of the unsaturated carboxylic acid and the derivatives thereof has better compatibility with the wood flour, and simultaneously the wood flour can be uniformly dispersed in the wood-plastic material along with the flow of the modified resin of the unsaturated carboxylic acid in the polyolefin resin because the modified resin of the unsaturated carboxylic acid and the derivatives thereof also have good compatibility with the polyolefin resin.

The modification form of the unsaturated carboxylic acid modified polyolefin can be various forms such as blending, copolymerization, grafting and the like, the blending refers to that a single or multiple unsaturated carboxylic acids are subjected to polymerization reaction to obtain polymers taking the unsaturated carboxylic acids as monomers, such as polyacrylic acid, polybutene acid, polyacrylic acid and polybutene acid copolymers and the like, the polymers are added into the original wood-plastic surface layer material, and the polymers are melted and blended to obtain the modified wood-plastic surface layer material, in the modification method, the unsaturated carboxylic acids do not directly react with the polyolefin resin in the wood-plastic surface layer, and only the mixing in a physical mode is carried out (the crosslinking condition among high molecular chains is not considered); copolymerization refers to adding unsaturated carboxylic acid during the synthesis of polyolefin resin to obtain copolymer of olefin monomer and unsaturated carboxylic acid monomer, such as chain structure of ethylene-polypropylene-ethylene; the grafting means that after the synthesis of the polyolefin resin is completed, a grafting reaction is performed on a polymer chain to add a side chain structure to the polymer chain so that the polymer chain additionally obtains a group.

Preferably, the adhesive material is maleic anhydride grafted polyethylene.

Preferably, the wood-plastic material for forming the middle layer comprises 15-25 parts of polyethylene, 10-20 parts of maleic anhydride grafted polyethylene, 30-50 parts of plant fiber powder and 10-20 parts of filler. The above are the main components of the wood-plastic material, obviously, some functional additives such as lubricant, antioxidant and the like are often added in the industrial production to facilitate the production or improve the product performance, and the additives are all in the prior art and are commonly used, so the invention is not repeated.

Preferably, the ionic polymerization resin reinforced polyolefin plastic is used as a co-extrusion surface layer, and the co-extrusion surface layer comprises 20-30% by mass of ethylene- (methyl) acrylate and not less than 60% by mass of polyethylene. Since the ionomer resin composite is used as a surface layer, some weather resistance enhancing treatment is required, and further, an antioxidant, a light stabilizer, and an ultraviolet absorber are added to the ionomer resin composite. In the polyolefin resin, the compatibility of the polyethylene and the ethylene- (methyl) acrylate is optimal, the polyethylene and the ethylene- (methyl) acrylate can be well and uniformly mixed, and the microstructure is favorably formed, so the polyethylene is selected as one of the matrixes of the co-extrusion surface layer.

The ionic polymer resin refers to a resin having ionic characteristics, such as sodium salt or zinc salt of a polymer, e.g., an ethylene methacrylic acid polymer, an ethylene acrylic acid polymer, an acrylic acid-ethylene-methacrylic acid terpolymer, or the like, formed by substituting a part of groups on a side chain of a polymer chain constituting the resin with metal ions. The ionic polymerization resin used in actual production is represented by surlyn resin, which is a product formed by introducing sodium or zinc ions into an ethylene-methacrylic acid copolymer for crosslinking, ionic bonds between different high molecular chains of the ethylene-methacrylic acid copolymer or different regions of the same high molecular chain can generate strong crosslinking action, so that the physical performance of the ionic polymerization resin is improved, but the crosslinking action is reversible, and when the ionic polymerization resin is heated, the strong attraction between adjacent molecules is weakened, so that the material is melted and flows, therefore, the ionic polymerization resin has better melt processing performance, and when the ionic polymerization resin is cooled, the bonding action is re-established, so that the physical strength of the ionic polymerization resin is recovered.

In the prior art, the ionic polymer resin is generally applied in the form of a film or a laminated sheet, and in these structures, the ionic polymer resin is generally used as a main constituent material of a laminated structure and has a main mass ratio. The coating layer is preferably formed by taking the vinyl resin as the main body and the ionic polymer resin as the auxiliary material, so that the coating layer has lower cost compared with an application method of directly using the ionic polymer resin or taking the ionic polymer resin as the main material. When polyethylene and ionic polymerization resin are mixed, the ionic polymerization resin can generate directional arrangement on the surface of the coating layer to a certain extent, so that a surface layer structure mainly composed of the ionic polymerization resin is formed, the wear resistance of the surface layer structure is stronger than that of polyolefin resin, and the interior of the surface layer structure can be protected. From the physical point of view, the occurrence of abrasion is essentially the interaction between the surface layers of two objects, so that the internal structure does not contribute much to the improvement of the surface abrasion resistance, and therefore, the replacement of the internal ionomer resin with the polyolefin resin does not cause obvious influence on the abrasion resistance, but can greatly reduce the production cost and obtain higher economic benefit. From another perspective, in order to meet the use requirement of the profile, the coating layer needs to reach a certain thickness, and the ionomer resin is usually in a thin film form during the use process, and the coating layer structure with a certain thickness can be conveniently formed by blending with the polyethylene resin.

In the present invention, the core material may be a metal core layer represented by an aluminum alloy or may be a synthetic polymer material. The synthetic polymer material is preferably a thermosetting resin composite material. Specifically, the metal core material is made of light aluminum alloy convenient to process, and the thermosetting resin composite material is made of high-temperature-resistant glass fiber reinforced plastic with high physical strength. The glass fiber reinforced plastic is not particularly limited to a composite material made of glass fiber and synthetic resin. The composite process of reinforcing fiber and synthetic resin uses glass fiber as reinforcing material, and the produced fiber reinforced composite material has high mechanical strength and may be used to replace steel and other metal in some fields. With the development of fiber reinforced technology, various fiber materials are available, such as carbon fiber, boron fiber, aramid fiber, alumina fiber, silicon carbide fiber, etc., and although the fiber reinforced composite material produced by using these fibers does not contain a glass component, it is called glass fiber reinforced plastic (frp) because of the habitual problem.

Preferably, when the aluminum alloy is selected as the core material, the surface of the aluminum alloy core material is provided with an oxide film. The oxide film here means an aluminum oxide film formed on the surface of an aluminum material by subjecting the aluminum material to a surface treatment by a physical or chemical method.

Preferably, when the aluminum alloy is selected as the core material, the surface of the aluminum alloy is provided with a groove along the length direction of the metal core material, and the depth of the groove is 0.3-1.0 mm.

Preferably, the thickness of the adhesive layer is 0.5-2.0 mm, and the thickness of the adhesive layer is greater than the depth of the groove.

The main effect of slot is on macrostructure and gluing layer formation gomphosis structure, increases the area of contact of gluing layer and aluminum alloy core to improve bonding strength. The longitudinal direction herein is not limited to a straight line, and may be a curved groove as long as the groove runs substantially along the longitudinal direction of the aluminum alloy core material, and it is preferable to form a regular straight groove. Another effect of the slot that sets up along core length direction lies in that when the cladding of gluing layer was carried out on the core surface, the gas that leaves or produce between gluing layer and the core can be followed the slot and is followed the direction opposite with aluminum alloy core motion direction and discharge to avoid producing the gas pocket between gluing layer and the aluminum alloy core. The cross section of the groove is preferably designed into a shape with the groove width decreasing from the groove opening to the groove bottom, such as an inverted triangle, a circular arc and the like, so that the interlayer material can enter the groove. Preferably, the aluminum alloy core material is first subjected to physical treatment to form the groove and then subjected to chemical treatment to form the oxide film, so that the oxide film is not damaged during groove processing. The grooves may be formed directly by the action of a die during extrusion molding of the aluminum alloy core material, or may be formed by subjecting the aluminum alloy core material to a secondary processing treatment.

In summary, the following beneficial effects can be achieved by applying the technical scheme of the invention:

1. according to the invention, the multi-layer coated co-extruded plate is produced by taking hard materials such as aluminum alloy or glass fiber reinforced plastic as core materials, the core materials can provide higher physical strength for the section bar, so that the bearing capacity of the section bar is obviously improved compared with that of wood-plastic materials, the wood-plastic materials in the middle layer can form a wood-like effect, meanwhile, the protection effect is provided for the peripheral surface layer of the core materials, the co-extruded surface layer plays a role in enhancing the surface layer performance, and the overall quality of the section bar is greatly improved compared with that of the existing product.

2. The invention adopts the co-extrusion process to produce the multilayer cladding plate and clad the wear-resistant surface layer, the section can be integrally formed from the die, and compared with the prior reinforced processes such as photocuring coating, alumina paster and the like, the invention has the advantages of shorter process flow and higher production efficiency.

3. The invention adopts a co-extrusion process to produce a multi-layer clad plate, wherein a section bar made of hard materials such as aluminum alloy or glass fiber reinforced plastics and the like is firstly clad with a wood-plastic material layer, and then an outer cladding layer made of one of thermoplastic elasticity, thermoplastic engineering plastics, ionic polymerization resin and polyolefin plastics reinforced by the ionic polymerization resin is further clad outside the wood-plastic material layer; the prior art shows that the direct coating of the outer cladding layer has high difficulty and poor effect due to large difference of material properties. After the wood-plastic layer is introduced as the transition layer, the material property difference between the core layer and the outer cladding layer can be remarkably buffered; the bonding property of the wood-plastic layer and the core material is good, and the bonding property of the wood-plastic layer and the outer coating layer is also good; the wood-plastic layer in the structure not only plays a role in convenient combination in production and manufacturing, but also plays a good stress buffering role in the using process of the product; in the environment of rapid cooling and heating, the capability of coping with thermal stress is improved, the quality of the product tends to be stable, the use effect of the product is improved, and the service life of the product is prolonged;

4. according to the invention, polyurethane hot melt adhesive and unsaturated carboxylic acid modified polyolefin hot melt adhesive are respectively adopted as materials of the first adhesive layer and the second adhesive layer, the polyurethane hot melt adhesive contains a large amount of NCO groups, and the NCO groups can generate strong adsorption effect with metal materials so as to be capable of generating bonding with metal; the unsaturated carboxylic acid modified polyolefin hot melt adhesive has polar groups, and the polar groups have good compatibility with wood flour in the wood-plastic material, so that the outer coating layer can firmly coat the core material based on the wood-plastic intermediate layer and two adhesives. In addition, maleic anhydride grafted polyethylene can be added into the wood-plastic middle layer, so that the rate of fusion with the surface layer of the adhesive layer is increased when the middle layer is extruded, and the fusion degree is improved.

Detailed Description

The technical solution of the present invention will be further described below by means of specific embodiments.

For the convenience of comparative performance tests, the specification of the core materials of glass fiber reinforced plastics, aluminum alloys or other materials used in the examples and the examples are 200mm by 100mm by 1000 mm. In addition, the surface of the aluminum alloy core material is pretreated to form an oxide film, and a plurality of grooves with the depth of 0.5mm are arranged along the length direction of the aluminum alloy core material. The coating of the adhesive layer is only required to be performed by adopting an extrusion process, which belongs to the prior art, and therefore, the details are not repeated in the embodiment and the comparative example.

Example 1

S1, providing a rigid core material;

s2, preheating the rigid core material, and then introducing the rigid core material into a core material channel of a co-extrusion die; meanwhile, a first adhesive is melted and extruded through a first extruder and enters a first adhesive runner of a co-extrusion die, so that the first adhesive is coated on the periphery of the rigid core material to form a glue-coated core material; then, the polyolefin wood-plastic material is melted and plasticized by a second extruder and then extruded into an intermediate layer runner of a co-extrusion die, so that the polyolefin wood-plastic material coats the glue-coated core material to form an intermediate layer, and a first coated core material is obtained; then, a second adhesive is melted and extruded through a third extruder and enters a second adhesive runner of a co-extrusion die, so that the second adhesive is coated on the periphery of the first coating core material to form a second coating core material; then, extruding the surface material into a surface runner of a co-extrusion die after the surface material is melted and plasticized by a fourth extruder, so that the surface material coats the second rubber-coated core material to form a co-extrusion surface layer, thereby obtaining a second coated core material;

s3, after being led out from a die orifice of the co-extrusion die, the second coating core material is naturally cooled or cooled by water to form a multi-layer coating co-extrusion section;

the rigid core material is aluminum alloy;

the first adhesive layer is polyurethane hot melt adhesive;

the second adhesive layer is maleic anhydride grafted modified polyethylene hot melt adhesive;

the polyolefin wood-plastic material comprises 25 parts of polyethylene, 50 parts of plant fiber powder, 15 parts of filler, 1 part of antioxidant, 4 parts of lubricant, 3 parts of plasticizer and 2 parts of coupling agent; the surface layer material comprises 95 parts of ASA resin, 0.8 part of antioxidant, 0.5 part of light stabilizer, 3 parts of lubricant and 3 parts of plasticizer.

Example 2

S1, providing a rigid core material;

s2, preheating the rigid core material, and then introducing the rigid core material into a core material channel of a co-extrusion die; meanwhile, a first adhesive is melted and extruded through a first extruder and enters a first adhesive runner of a co-extrusion die, so that the first adhesive is coated on the periphery of the rigid core material to form a glue-coated core material; then, the polyolefin wood-plastic material is melted and plasticized by a second extruder and then extruded into an intermediate layer runner of a co-extrusion die, so that the polyolefin wood-plastic material coats the glue-coated core material to form an intermediate layer, and a first coated core material is obtained; then, a second adhesive is melted and extruded through a third extruder and enters a second adhesive runner of a co-extrusion die, so that the second adhesive is coated on the periphery of the first coating core material to form a second coating core material; then, extruding the surface material into a surface runner of a co-extrusion die after the surface material is melted and plasticized by a fourth extruder, so that the surface material coats the second rubber-coated core material to form a co-extrusion surface layer, thereby obtaining a second coated core material;

s3, after being led out from a die orifice of the co-extrusion die, the second coating core material is naturally cooled or cooled by water to form a multi-layer coating co-extrusion section;

the rigid core material is aluminum alloy;

the first adhesive layer is polyurethane hot melt adhesive;

the second adhesive layer is maleic anhydride grafted modified polyethylene hot melt adhesive;

the polyolefin wood-plastic material comprises 25 parts of polyethylene, 50 parts of plant fiber powder, 15 parts of filler, 1 part of antioxidant, 5 parts of lubricant, 3 parts of plasticizer and 2 parts of coupling agent; the surface layer material comprises 96 parts of TPU, 0.8 part of antioxidant, 0.5 part of light stabilizer and 1.5 parts of plasticizer.

Example 3

S1, providing a rigid core material;

s2, preheating the rigid core material, and then introducing the rigid core material into a core material channel of a co-extrusion die; meanwhile, a first adhesive is melted and extruded through a first extruder and enters a first adhesive runner of a co-extrusion die, so that the first adhesive is coated on the periphery of the rigid core material to form a glue-coated core material; then, the polyolefin wood-plastic material is melted and plasticized by a second extruder and then extruded into an intermediate layer runner of a co-extrusion die, so that the polyolefin wood-plastic material coats the glue-coated core material to form an intermediate layer, and a first coated core material is obtained; then, a second adhesive is melted and extruded through a third extruder and enters a second adhesive runner of a co-extrusion die, so that the second adhesive is coated on the periphery of the first coating core material to form a second coating core material; then, extruding the surface material into a surface runner of a co-extrusion die after the surface material is melted and plasticized by a fourth extruder, so that the surface material coats the second rubber-coated core material to form a co-extrusion surface layer, thereby obtaining a second coated core material;

s3, after being led out from a die orifice of the co-extrusion die, the second coating core material is naturally cooled or cooled by water to form a multi-layer coating co-extrusion section;

the rigid core material is aluminum alloy;

the first adhesive layer is polyurethane hot melt adhesive;

the second adhesive layer is maleic anhydride grafted modified polyethylene hot melt adhesive;

the polyolefin wood-plastic material comprises 20 parts of polyethylene, 10 parts of maleic anhydride grafted polyethylene, 50 parts of plant fiber powder, 15 parts of filler, 1 part of antioxidant, 5 parts of lubricant and 3 parts of plasticizer; the surface layer material comprises 96 parts of ethylene- (methyl) sodium acrylate, 0.8 part of antioxidant, 0.5 part of light stabilizer, 1.5 parts of plasticizer and 2 parts of HDPE.

Example 4

S1, providing a rigid core material;

s2, preheating the rigid core material, and then introducing the rigid core material into a core material channel of a co-extrusion die; meanwhile, a first adhesive is melted and extruded through a first extruder and enters a first adhesive runner of a co-extrusion die, so that the first adhesive is coated on the periphery of the rigid core material to form a glue-coated core material; then, the polyolefin wood-plastic material is melted and plasticized by a second extruder and then extruded into an intermediate layer runner of a co-extrusion die, so that the polyolefin wood-plastic material coats the glue-coated core material to form an intermediate layer, and a first coated core material is obtained; then, a second adhesive is melted and extruded through a third extruder and enters a second adhesive runner of a co-extrusion die, so that the second adhesive is coated on the periphery of the first coating core material to form a second coating core material; then, extruding the surface material into a surface runner of a co-extrusion die after the surface material is melted and plasticized by a fourth extruder, so that the surface material coats the second rubber-coated core material to form a co-extrusion surface layer, thereby obtaining a second coated core material;

s3, after being led out from a die orifice of the co-extrusion die, the second coating core material is naturally cooled or cooled by water to form a multi-layer coating co-extrusion section;

the rigid core material is glass fiber reinforced plastic;

the first adhesive layer is polyurethane hot melt adhesive;

the second adhesive layer is maleic anhydride grafted modified polyethylene hot melt adhesive;

the polyolefin wood-plastic material comprises 20 parts of polyethylene, 10 parts of maleic anhydride grafted polyethylene, 50 parts of plant fiber powder, 15 parts of filler, 1 part of antioxidant, 5 parts of lubricant and 3 parts of plasticizer; the surface layer material comprises 25 parts of ethylene- (methyl) sodium acrylate, 70 parts of HDPE, 0.8 part of antioxidant, 0.5 part of light stabilizer and 1.5 parts of plasticizer.

Example 5

S1, providing a rigid core material;

s2, preheating the rigid core material, and then introducing the rigid core material into a core material channel of a co-extrusion die; meanwhile, a first adhesive is melted and extruded through a first extruder and enters a first adhesive runner of a co-extrusion die, so that the first adhesive is coated on the periphery of the rigid core material to form a glue-coated core material; then, the polyolefin wood-plastic material is melted and plasticized by a second extruder and then extruded into an intermediate layer runner of a co-extrusion die, so that the polyolefin wood-plastic material coats the glue-coated core material to form an intermediate layer, and a first coated core material is obtained; then, a second adhesive is melted and extruded through a third extruder and enters a second adhesive runner of a co-extrusion die, so that the second adhesive is coated on the periphery of the first coating core material to form a second coating core material; then, extruding the surface material into a surface runner of a co-extrusion die after the surface material is melted and plasticized by a fourth extruder, so that the surface material coats the second rubber-coated core material to form a co-extrusion surface layer, thereby obtaining a second coated core material;

s3, after being led out from a die orifice of the co-extrusion die, the second coating core material is naturally cooled or cooled by water to form a multi-layer coating co-extrusion section;

the rigid core material is glass fiber reinforced plastic;

the first adhesive layer is polyurethane hot melt adhesive;

the second adhesive layer is maleic anhydride grafted modified polyethylene hot melt adhesive;

the polyolefin wood-plastic material comprises 20 parts of polyethylene, 10 parts of maleic anhydride grafted polyethylene, 50 parts of plant fiber powder, 15 parts of filler, 1 part of antioxidant, 5 parts of lubricant and 3 parts of plasticizer; the surface layer material comprises 25 parts of ethylene- (methyl) sodium acrylate, 70 parts of HDPE, 0.8 part of antioxidant, 0.5 part of light stabilizer and 1.5 parts of plasticizer.

Comparative example 1

S1, prefabricating an aluminum alloy core material, wherein the periphery of the aluminum alloy core material is coated with an adhesive layer formed by polyurethane hot melt adhesive;

and S2, heating the aluminum alloy core material to melt and soften the adhesive layer on the surface. Then guiding the core material into a core material channel of a co-extrusion die; meanwhile, the polyolefin wood-plastic material is extruded into a middle layer runner of a co-extrusion die after being melted and plasticized by an extruder, so that the polyolefin wood-plastic material coats the core material to form a wood-plastic layer, and a wood-plastic coated core material is obtained; then leading out the wood-plastic coated core material from a co-extrusion die to prepare a section;

s3, cooling and shaping the section to obtain a composite section;

the polyolefin wood-plastic material comprises 25 parts of polyethylene, 50 parts of plant fiber powder, 15 parts of filler, 1 part of antioxidant, 4 parts of lubricant, 3 parts of plasticizer and 2 parts of coupling agent.

Comparative example 2

S1, prefabricating an aluminum alloy core material, wherein the periphery of the aluminum alloy core material is coated with an adhesive layer formed by polyurethane hot melt adhesive;

s2, heating the aluminum alloy core material to melt and soften the adhesive layer on the surface; then guiding the core material into a core material channel of a co-extrusion die; meanwhile, extruding the surface material into a middle layer flow channel of a co-extrusion die after the surface material is melted and plasticized by an extruder, so that the polyolefin wood-plastic material coats the core material to form a wood-plastic layer, thereby obtaining a coated core material; then leading out the coated core material from a co-extrusion die to prepare a profile;

s3, cooling and shaping the section to obtain a composite section;

wherein the surface layer material comprises 95 parts of ASA resin, 0.8 part of antioxidant, 0.5 part of light stabilizer, 3 parts of lubricant and 3 parts of plasticizer.

The following are performance tests for examples 1 to 5 and comparative examples 1 to 2.

And (3) testing the wear resistance: adopt dull and stereotyped friction pulley experimental method, with on the fixed revolving stage of sample, be equipped with the rubber wheel of rigidity on the revolving stage, the rubber wheel can rub the sample when the revolving stage rotates. Specifically, the load during the test is 1kg, the rotating speed is 72 revolutions per minute, and the mass retention rate of the sample after 5000 revolutions is analyzed to compare the wear resistance.

And (3) testing the bonding strength: testing according to the method of GB/T17657-2013, adhering a steel clamping head with the size of 20mm x 20mm on a sample by using an HY-914 quick adhesive, cutting off an adhesive layer along the outline of the steel clamping head, after the adhesion is firm, pulling up the steel clamping head by using a tension meter along the direction vertical to the plane of the plate, or placing the steel clamping head on the steel clamping head downwards to suspend a heavy object and recording the gravity of the heavy object, recording the maximum tension (N) or the maximum gravity before the hot melt adhesive and the aluminum alloy plate are delaminated, recording the maximum gravity as F, and then, judging the internal bonding strength as P = F/S, wherein S is the area of the steel clamping head;

and (3) testing cold and hot weather resistance: taking the test piece, putting the test piece into an air convection drying box at the temperature of 63 +/-3 ℃ for drying for 2 hours, taking out the test piece, and immediately putting the test piece into a constant temperature and humidity box at the temperature of minus 20 +/-3 ℃ for 2 hours; and repeating the steps for six times, taking out the test piece, and observing whether the surface of the test piece has visible defects such as cracks, bubbles, discoloration, wrinkling, delamination and the like when the temperature reaches the room temperature. And then, performing secondary bonding strength test on the test piece subjected to cold and hot treatment by the method used in the table I.

The test results are shown in table one.

Watch 1

As can be seen from the table above, compared with the mode that the wood-plastic material is directly exposed outside, the arrangement of the co-extrusion surface layer improves the surface layer wear resistance of the profile, so that the service life of the profile is longer. It can be seen from comparative example 2 that the co-extruded surface layer directly coated on the adhesive layer has poor cold and hot stability, and an obvious defect appears after a multi-round cold and hot cycle test is performed, while the cold and hot stability is guaranteed after the wood-plastic layer is added between the co-extruded surface layer and the core material in embodiment 1. Through analysis, the possible reason is that the basic material of the co-extrusion surface layer is plastic, the material of the core material is aluminum alloy, and when the co-extrusion surface layer is subjected to cold and heat changes, the expansion and contraction rate of the plastic is far greater than that of the aluminum alloy, so that after multiple times of expansion and contraction deformation, the adhesive layer is stressed and fatigued to cause the loss of the bonding strength. Compared with the prior art, the wood-plastic composite material contains a large amount of wood powder, and the wood powder is wrapped by the plastic, which is equivalent to the plastic modified wood powder, obviously, the expansion and contraction rate of the plastic modified wood powder is between that of the plastic and that of the metal, and the plastic modified wood powder can play an obvious buffering role, so that the middle layer can relatively not obviously damage the adhesive layer structure when undergoing cold and hot changes, and on the other hand, the middle layer has elasticity compared with the metal core material, the expansion and contraction change of the co-extrusion surface layer can be buffered due to the elasticity of the middle layer, and therefore, the adhesion between the co-extrusion surface layer and the middle layer can not be damaged. In conclusion, the multilayer coating section provided by the invention has excellent physical properties, and a complementary effect is formed between layers, so that the overall quality of the section is improved.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.