Method for preparing cross-linked polyethylene short fiber reinforced polyethylene composite material

Abstract

The invention discloses a method for reinforcing a polyethylene composite material by using crosslinked polyethylene short fibers, and belongs to the technical field of high polymer materials. The cross-linked polyethylene short fiber has the advantages of good compatibility with polyethylene, approximate modulus, low rigidity, no melting or dissolving, creep resistance and temperature resistance, and is suitable for being used in some products requiring low rigidity and high performance; as the crosslinked polyethylene short fibers have the characteristics of no melting and no dissolving and have good absorbability for the pretreatment liquid, the silane-peroxide system is adopted to treat the crosslinked polyethylene short fibers, the interface bonding between the short fibers and the polyethylene is enhanced, and the pretreatment liquid is prevented from being dispersed into the polyethylene to cause crosslinking of the polyethylene, so that the service life of the polyethylene is prolonged, and the service life of the polyethylene is prolonged. And the machinability of the material is ensured.

Description

Technical Field

[0001] The present application belongs to the technical field of polymer materials, and in particular, relates to a method for cross-linking polyethylene short fibers to reinforce polyethylene composite materials. Background Art

[0002] Polyethylene (PE) is a thermoplastic resin with low price, moderate performance and wide application. In order to meet the application fields of different applications, cross-linking, fiber filling modification and other methods are often used to improve the various properties of polyethylene products.

[0003] Cross-linking modification is a chemical cross-linking method that connects polyethylene molecular chains through covalent bonds to form a cross-linked polyethylene material, which can significantly improve the strength, temperature resistance, creep resistance and other properties of the material. However, the cross-linking reaction is irreversible, and the cross-linked material is insoluble, cannot be recycled or hot-melted; fiber filling modification is a common polyethylene modification method. Patent CN101671456B discloses a glass fiber reinforced polyethylene material and a preparation method thereof. The patent introduces glass fiber into polyethylene products to improve the physical and mechanical properties; Patent CN107383552A discloses a preparation method of a carbon fiber reinforced polyethylene composite material. The patent immerses the carbon fiber in an impregnation solution, mixes it with polyethylene through an internal mixer, and then forms it through hot pressing and cold pressing.

[0004] However, experiments have shown that since the modulus of reinforcing fibers such as glass fiber and carbon fiber is much higher than that of polyethylene, the fiber-reinforced polyethylene material prepared by the above method will greatly increase the rigidity of the material and cannot be used in some products that require low rigidity. In addition, the compatibility of glass fiber, carbon fiber and polyethylene is poor, and a compatibilizer is required to improve the interfacial bonding strength between the fiber and polyethylene, but the problem of interface separation will still occur when deformation occurs. Summary of the invention

[0005] The purpose of the implementation of this application is to provide a method for cross-linking polyethylene short fiber reinforced polyethylene composite materials to solve the technical problem that the existing polyethylene modification method adds reinforcing fibers with a large modulus difference from the polyethylene, resulting in poor polyethylene interface bonding ability and high rigidity.

[0006] To achieve the above purpose, the technical solution adopted in this application is: to provide a method for cross-linking polyethylene short fiber reinforced polyethylene composite material, which specifically includes the following steps:

[0007] The cross-linked polyethylene staple fibers are soaked in a pretreatment solution, taken out and dried, and mixed with polyethylene pellets to obtain a dispersed mixture; the dispersed mixture is extruded and granulated to obtain a cross-linked polyethylene staple fiber reinforced polyethylene composite material;

[0008] The pretreatment solution includes organic silicon and a peroxide initiator.

[0009] In one embodiment,

[0010] The organosilicon is one or more of vinyltrimethoxysilane, vinyltriethoxysilane or vinyltriisopropoxysilane. Preferably, the organosilicon is vinyltrimethoxysilane.

[0011] In one embodiment,

[0012] The peroxide initiator is one of 2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane, diisopropylbenzene peroxide, di-tert-butyl hydroperoxide or di-tert-butyl peroxyisopropylbenzene. Preferably, the peroxide initiator is di-tert-butyl hydroperoxide.

[0013] In one embodiment,

[0014] The mass ratio of the organosilicon to the peroxide initiator is 1:0.02-0.05. Preferably, the mass ratio of the organosilicon to the peroxide initiator is 1:0.05.

[0015] In one embodiment,

[0016] The cross-linked polyethylene staple fibers are immersed in the pretreatment solution at room temperature for 1-3 minutes.

[0017] In one embodiment,

[0018] The cross-linked polyethylene staple fibers have a monofilament diameter of 10-100 nm, a staple fiber length of 2-15 mm, and a cross-linking degree of 69-80%. Preferably, the monofilament diameter of the cross-linked polyethylene staple fibers is 10 nm, the staple fiber length is 2 mm, and the cross-linking degree is 69%.

[0019] In one embodiment,

[0020] The mass ratio of the cross-linked polyethylene staple fibers to the polyethylene pellets is 5:95-30:70. Preferably, the mass ratio of the cross-linked polyethylene staple fibers to the polyethylene pellets is 30:70.

[0021] In one embodiment,

[0022] The extrusion granulation adopts a twin-screw extrusion granulator.

[0023] In one embodiment,

[0024] The extrusion temperature of the twin-screw extruder granulator is 180-220° C. with a gradient temperature increase.

[0025] In one embodiment,

[0026] The gradient temperature increase is one gradient of 5°C.

[0027] The present application provides a method for cross-linking polyethylene staple fiber reinforced polyethylene composite material, the method uses cross-linked polyethylene staple fiber as a reinforcing component and polyethylene as a matrix, the cross-linked polyethylene staple fiber has good compatibility with polyethylene, and when filled into the polyethylene matrix, it will not melt at the corresponding processing temperature, can maintain the shape of the fiber, and has the advantages of similar modulus, low rigidity, infusibility, creep resistance, and temperature resistance, and is suitable for use in some products requiring low rigidity and high performance; since the cross-linked polyethylene staple fiber has the characteristics of infusibility and insolubility, and has good absorption of pretreatment liquid, the cross-linked polyethylene staple fiber is treated with a silane-peroxide system, the interface bonding between the staple fiber and the polyethylene is enhanced, and even if deformation occurs, the interface separation will not occur, the staple fiber can prevent the pretreatment liquid from dispersing into the polyethylene, causing the polyethylene to be cross-linked, thereby ensuring the processability of the material, improving the performance of the polyethylene composite material, and making it more widely used, and the method is simple, low cost, and suitable for industrial production. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear, the present application is further described in detail. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] Example 1

[0030] Vinyl trimethoxysilane and di-tert-butyl hydroperoxide are mixed in a ratio of 1:0.05 to form a uniform liquid as a pretreatment liquid; cross-linked polyethylene staple fibers with a single filament diameter of 10 nm, a staple length of 2 mm, and a cross-linking degree of 69% are selected, and the cross-linked polyethylene staple fibers are immersed in the pretreatment liquid for 3 minutes, and the pretreatment liquid is taken out and controlled to dry; 30 parts by weight of the cross-linked polyethylene fibers and 70 parts by weight of polyethylene pellets are added to a vertical mixer, and stirred for 10 minutes to obtain a dispersed mixture; the dispersed mixture is extruded and granulated by a twin-screw extruder granulator, and the extruder temperature is gradually increased from 180 to 220°C, and the gradient temperature increase is one gradient of 5°C to obtain a cross-linked polyethylene staple fiber reinforced polyethylene composite material.

[0031] Example 2

[0032] Vinyl triethoxysilane and di-tert-butyl peroxy isopropylbenzene are mixed in a ratio of 1:0.02 to form a uniform liquid as a pretreatment liquid; cross-linked polyethylene staple fibers with a single fiber diameter of 50 nm, a staple length of 10 mm, and a cross-linking degree of 69% are selected, and the cross-linked polyethylene staple fibers are immersed in the pretreatment liquid for 3 minutes, and the pretreatment liquid is drained after being taken out; 15 parts by weight of the cross-linked polyethylene fibers and 85 parts by weight of polyethylene pellets are added to a vertical mixer, and stirred for 10 minutes to obtain a dispersed mixture; the dispersed mixture is extruded and granulated by a twin-screw extruder granulator, and the extruder temperature is gradually increased from 180 to 220°C, and the gradient temperature increase is one gradient of 5°C to obtain a cross-linked polyethylene staple fiber reinforced polyethylene composite material.

[0033] Example 3

[0034] Vinyl triisopropoxy silane and dicumyl peroxide are mixed in a ratio of 1:0.035 to form a uniform liquid as a pretreatment liquid; cross-linked polyethylene staple fibers with a single filament diameter of 70 nm, a staple length of 15 mm, and a cross-linking degree of 69% are selected, and the cross-linked polyethylene staple fibers are immersed in the pretreatment liquid for 3 minutes, and the pretreatment liquid is taken out and controlled to dry; 20 parts by weight of the cross-linked polyethylene fibers and 80 parts by weight of polyethylene pellets are added to a vertical mixer, and stirred for 10 minutes to obtain a dispersed mixture; the dispersed mixture is extruded and granulated by a twin-screw extruder granulator, and the extruder temperature is gradually increased from 180 to 220°C, and the gradient temperature increase is one gradient of 5°C to obtain a cross-linked polyethylene staple fiber reinforced polyethylene composite material.

[0035] Example 4

[0036] Vinyl triisopropoxysilane and 2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane are mixed in a ratio of 1:0.045 to form a uniform liquid as a pretreatment liquid; cross-linked polyethylene staple fibers with a single fiber diameter of 100 nm, a staple length of 10 mm, and a cross-linking degree of 69% are selected, and the cross-linked polyethylene staple fibers are immersed in the pretreatment liquid for 3 minutes, and the pretreatment liquid is taken out and controlled dry; 30 parts by weight of the cross-linked polyethylene fibers and 70 parts by weight of polyethylene pellets are added to a vertical mixer, stirred for 10 minutes, and a dispersed mixture is obtained; the dispersed mixture is extruded and granulated by a twin-screw extruder granulator, the extruder temperature is gradually increased from 180 to 220°C, and the gradient temperature increase is one gradient of 5°C, to obtain a cross-linked polyethylene staple fiber reinforced polyethylene composite material.

[0037] Example 5

[0038] The present embodiment is different from the embodiment 1 in that the organic silicon is a mixture of vinyltrimethoxysilane and vinyltriethoxysilane in a mixing ratio of 1:1, and the other operations are the same.

[0039] Example 6

[0040] The difference between this embodiment and embodiment 1 is that the cross-linked polyethylene staple fibers are immersed in the pretreatment solution for 1 minute, and the other operations are the same.

[0041] Example 7

[0042] The difference between this embodiment and embodiment 1 is that the mass ratio of the cross-linked polyethylene staple fibers to the polyethylene pellets is 5:95, and the remaining operations are the same.

[0043] Example 8

[0044] The difference between this embodiment and embodiment 1 is that the cross-linking degree of the cross-linked polyethylene staple fibers is 80%, and the other operations are the same.

[0045] Example 9

[0046] The difference between this embodiment and embodiment 1 is that the cross-linking degree of the cross-linked polyethylene staple fibers is 75%, and the other operations are the same.

[0047] The present application provides a method for cross-linked polyethylene staple fiber reinforced polyethylene composite material, which comprises soaking the cross-linked polyethylene staple fiber in a pretreatment liquid, taking it out and controlling to dry it, and mixing it with polyethylene pellets to obtain a dispersed mixture; extruding and granulating the dispersed mixture to obtain a cross-linked polyethylene staple fiber reinforced polyethylene composite material; the method uses cross-linked polyethylene staple fiber as a reinforcing component and polyethylene as a matrix, the cross-linked polyethylene staple fiber has good compatibility with polyethylene, and when filled into the polyethylene matrix, the cross-linked polyethylene staple fiber will not melt at the corresponding processing temperature, and can maintain the shape of the fiber, and has the advantages of close modulus, low rigidity, infusibility, creep resistance, and temperature resistance, and is suitable for use in some products requiring low rigidity and high performance; since the cross-linked polyethylene staple fiber has the characteristics of infusibility and insolubility, and has good absorption of the pretreatment liquid, the cross-linked polyethylene staple fiber is treated with a silane-peroxide system, so that the interface bonding between the staple fiber and the polyethylene is enhanced, and even if deformation occurs, the interface separation will not occur, and the staple fiber can prevent the pretreatment liquid from being dispersed into the polyethylene, causing the polyethylene to be cross-linked, thereby ensuring the processability of the material, improving the performance of the polyethylene composite material, and making it more widely used, and the method is simple, low cost, and suitable for industrial production.

[0048] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0049] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for cross-linking polyethylene short fiber reinforced polyethylene composite material, characterized in that: The specific steps include: The cross-linked polyethylene staple fibers are soaked in a pretreatment solution, taken out and dried, and mixed with polyethylene pellets to obtain a dispersed mixture; the dispersed mixture is extruded and granulated to obtain a cross-linked polyethylene staple fiber reinforced polyethylene composite material; The pretreatment solution includes organic silicon and a peroxide initiator.

2. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 1, characterized in that: The organic silicon is one or more of vinyl trimethoxy silane, vinyl triethoxy silane or vinyl triisopropoxy silane.

3. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 1, characterized in that: The peroxide initiator is one of 2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane, diisopropylbenzene peroxide, di-tert-butyl hydroperoxide or di-tert-butyl peroxyisopropylbenzene.

4. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 1, characterized in that: The mass ratio of the organosilicon to the peroxide initiator is 1:0.02-0.

05.

5. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 1, characterized in that: The cross-linked polyethylene staple fibers are immersed in the pretreatment solution at room temperature for 1-3 minutes.

6. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 1, characterized in that: The cross-linked polyethylene short fibers have a monofilament diameter of 10-100 nm, a short fiber length of 2-15 mm, and a cross-linking degree of 69-80%.

7. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 1, characterized in that: The mass ratio of the cross-linked polyethylene staple fibers to the polyethylene pellets is 5:95-30:

70.

8. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 1, characterized in that: The extrusion granulation adopts a twin-screw extrusion granulator.

9. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 8, characterized in that: The extrusion temperature of the twin-screw extruder granulator is 180-220° C. with a gradient temperature increase.

10. The method for cross-linking polyethylene short fiber reinforced polyethylene composite material according to claim 9, characterized in that: The gradient temperature increase is one gradient of 5°C.