阅读说明：本技术 一种纤维增强摩托车头盔复合塑料及制备方法 (Fiber-reinforced composite plastic for motorcycle helmet and preparation method thereof ) 是由 张道增 于 2019-12-03 设计创作，主要内容包括：本发明涉及头盔材料领域,特别是涉及一种纤维增强摩托车头盔复合塑料及制备方法。本发明通过蒸汽爆破处理使麻纤维疏松化,疏松化的麻纤维具有良好的微孔,并将发泡剂置于麻纤维的微孔,然后包覆热固性环氧树脂,在二级流化床热处理时,内置的发泡剂产生气体,使微孔得以保留,同时环氧树脂加热固化形成牢固的包覆层包覆纤维,得到的纤维为疏松的存在微孔的麻纤维；热固性树脂包覆麻纤维后,利于纤维聚碳酸酯/ABS体系中的相容和分散,疏松的麻纤维受热固性树脂保护,在后期造粒加工时麻纤维微孔不会被填堵,得到的复合塑料在成品头盔外壳中得到较好的微孔保留。赋予头盔外壳强度的同时具有优异的轻质、缓冲特性。(The invention relates to the field of helmet materials, in particular to a fiber-reinforced composite plastic for a motorcycle helmet and a preparation method thereof. According to the invention, the fibrilia is loosened through steam explosion treatment, the loosened fibrilia has good micropores, the foaming agent is placed in the micropores of the fibrilia, then thermosetting epoxy resin is coated, during secondary fluidized bed heat treatment, the built-in foaming agent generates gas to keep the micropores, meanwhile, the epoxy resin is heated and cured to form firm coating layers to coat the fibers, and the obtained fibers are loose fibrilia with micropores; after the fibrilia is coated by the thermosetting resin, the fibrilia is beneficial to the compatibility and dispersion in a fiber polycarbonate/ABS system, loose fibrilia is protected by the thermosetting resin, the micropores of the fibrilia cannot be filled up in the later granulation processing, and the obtained composite plastic can obtain better micropore retention in the shell of the finished helmet. Endows the strength of the helmet shell and has excellent light weight and buffering property.)

1. A preparation method of fiber-reinforced composite plastic for a motorcycle helmet is characterized by comprising the following steps: the preparation method comprises the following steps:

(1) carrying out steam explosion and loosening treatment on the fibrilia, dispersing azodicarbonamide and alkali liquor in a mass ratio of 1:5 to obtain foaming liquid, and spraying the foaming liquid on the exploded fibrilia to enable the foaming liquid to permeate the fibrilia; then drying at 80-100 ℃ to obtain the pretreated fibrilia;

(2) preparing liquid epoxy resin, pentaerythritol, toluene diisocyanate and a curing agent into colloidal liquid; adding the pretreated fibrilia into a high-speed stirrer for high-speed stirring, and spraying colloidal liquid on the pretreated fibrilia which is stirred and suspended at high speed to coat the colloidal liquid and permeate the fibrilia;

(3) transferring the fibrilia obtained in the step (2) into a second-stage heating fluidized bed, wherein the temperature of hot air flow of the first-stage fluidized bed is 120 ℃, and the temperature of hot air flow of the second-stage fluidized bed is 190 ℃; the colloidal liquid is pre-cured on the surfaces of the fibrilia through primary hot air flow suspension treatment and has certain flexibility, the secondary hot air flow suspension treatment is carried out at a higher temperature, so that azodicarbonamide permeated by the fibrilia generates gas to enable the fibrilia to form micropores, and the colloidal liquid is further cured to form a firm coating layer, thereby finally obtaining the loose fibrilia coated by the thermosetting epoxy resin;

(4) and (3) adding the loose fibrilia obtained in the step (3), polycarbonate, ABS, an antioxidant, a lubricant and a flame retardant into a high-speed mixer, uniformly mixing, extruding by a screw extruder, water-cooling, bracing, granulating, screening and dehydrating to obtain the fiber-reinforced motorcycle helmet composite plastic.

2. The preparation method of the fiber-reinforced composite plastic for the motorcycle helmet as claimed in claim 1, wherein the preparation method comprises the following steps: and (2) the steam explosion in the step (1) is to immerse the fibrilia in hot water to be fully softened, drain the water, place the fibrilia in a reaction vessel of a steam explosion device, heat the fibrilia until the pressure in the reaction vessel rises to 1.0-1.5MPa, maintain the pressure for 5min, and quickly release the pressure to loosen the fibrilia to form micropores.

3. The preparation method of the fiber-reinforced composite plastic for the motorcycle helmet as claimed in claim 1, wherein the preparation method comprises the following steps: and (2) controlling the spraying amount of the foaming liquid in the step (1) to be 3-5% of the mass of the fibrilia.

4. The preparation method of the fiber-reinforced composite plastic for the motorcycle helmet as claimed in claim 1, wherein the preparation method comprises the following steps: the colloidal liquid in the step (2) is prepared from liquid epoxy resin, pentaerythritol, toluene diisocyanate and a curing agent in a mass ratio of 40-50: 2-5: 1-3: 3-5, preparation; the liquid epoxy resin is bisphenol A type epoxy resin of Sanmu SM 609-50; the curing agent is dicyandiamide.

5. The preparation method of the fiber-reinforced composite plastic for the motorcycle helmet as claimed in claim 1, wherein the preparation method comprises the following steps: the spraying amount of the colloidal liquid in the step (2) is 5-10% of the mass of the pretreated fibrilia.

6. The preparation method of the fiber-reinforced composite plastic for the motorcycle helmet as claimed in claim 1, wherein the preparation method comprises the following steps: the raw materials in the step (4) are as follows by weight: 10-15 parts of loose fibrilia, 40-60 parts of polycarbonate, 30-50 parts of ABS, 0.05-0.1 part of antioxidant, 0.5-1 part of lubricant and 0.5-2 parts of flame retardant.

7. The preparation method of the fiber-reinforced composite plastic for the motorcycle helmet as claimed in claim 1, wherein the preparation method comprises the following steps: controlling the temperature of the high-speed mixer in the step (4) to be 80-110 ℃; the extrusion granulation temperature is controlled at 220-260 ℃.

8. A fibre reinforced motorcycle helmet composite plastic, characterised in that it is prepared by the process of any one of claims 1 to 7.

The technical field is as follows:

the invention relates to the field of helmet materials, in particular to a fiber-reinforced composite plastic for a motorcycle helmet and a preparation method thereof.

Background art:

the helmet is a head protection device mainly made of plastic and mainly comprises an outer shell, a buffer layer lining, a suspension device and the like. The shell is generally made of hard plastics such as ABS or PC with good abrasion resistance and compression resistance, and also made of carbon fiber composite materials or metal materials. The layer is required to be high in hardness, high in rigidity, wear-resistant and helpful for resisting penetration of sharp objects. At present, most helmet shell materials are reinforced, such as carbon fiber and glass fiber reinforced plastics. However, when used in helmet shell materials, it is important, in addition to the reinforcement, how to achieve the reinforcement while ensuring good cushioning and energy absorption properties of the plastic shell. Especially for a motorcycle moving at high speed, huge impact energy can be generated by instant collision, if the shell material cannot absorb energy and disperse the impact energy well, the buffering energy is far insufficient only by the buffer layer of the inner layer, and serious damage can be caused to the head.

The reinforcement can be realized, and simultaneously, good buffering and energy absorption effects can be generated, and technicians try to moderately foam the shell material, but the foaming has a relatively obvious influence on the strength.

Chinese patent CN105482480A discloses a bamboo fiber reinforced thermoplastic plastic, which is prepared by mixing the following raw materials in parts by weight: 30-60 parts of bamboo fiber, 30-80 parts of thermoplastic plastic, 0.25-0.6 part of coupling agent, 0.3-0.8 part of cross-linking agent and 0.5-1.5 parts of lubricating agent, and the bamboo fiber is pretreated to be used for reinforcing the plastic.

In view of the above, when the bamboo fiber and the hemp fiber are used for reinforcing the helmet shell plastic, the wood fiber is loose and light while the wood fiber is reinforced, and the shell material can be endowed with good buffering performance. However, when the wood fiber is processed in a thermoplastic system, the thermoplastic polymer, the lubricating assistant and the like can easily fill up the loose pores of the wood fiber, so that the loose performance of the wood fiber reinforced plastic is poor, and the buffering and energy absorption are not obvious.

The invention content is as follows:

aiming at the defects of low strength and insufficient shock resistance of the ABS/polycarbonate system adopted by the existing shell material of the motorcycle helmet, the invention provides a fiber reinforced composite plastic for the motorcycle helmet, which is remarkably different from the existing fiber reinforced plastic in that: the invention endows the fibrilia with micropores, firmly coats the thermosetting resin on the fibrilia, the fiber is easy to disperse in an ABS/polycarbonate system, and the fiber keeps loose micropores, thereby being used for a plastic shell to improve the shock resistance and effectively increase the elasticity of the shell to increase the buffer performance. Further provides a preparation method of the fiber reinforced composite plastic for the motorcycle helmet.

The purpose of the invention is realized by the following technical scheme:

the preparation method of the fiber reinforced composite plastic for the motorcycle helmet is characterized in that: the preparation method comprises the following steps:

(1) carrying out steam explosion and loosening treatment on the fibrilia, dispersing azodicarbonamide and alkali liquor in a mass ratio of 1:5 to obtain foaming liquid, and spraying the foaming liquid on the exploded fibrilia to enable the foaming liquid to permeate the fibrilia; then drying at 80-100 ℃ to obtain the pretreated fibrilia;

(2) preparing liquid epoxy resin, pentaerythritol, toluene diisocyanate and a curing agent into colloidal liquid; adding the pretreated fibrilia into a high-speed stirrer for high-speed stirring, and spraying colloidal liquid on the pretreated fibrilia which is stirred and suspended at high speed to coat the colloidal liquid and permeate the fibrilia;

(3) transferring the fibrilia obtained in the step (2) into a second-stage heating fluidized bed, wherein the temperature of hot air flow of the first-stage fluidized bed is 120 ℃, and the temperature of hot air flow of the second-stage fluidized bed is 190 ℃; the colloidal liquid is pre-cured on the surfaces of the fibrilia through primary hot air flow suspension treatment and has certain flexibility, the secondary hot air flow suspension treatment is carried out at a higher temperature, so that azodicarbonamide permeated by the fibrilia generates gas to enable the fibrilia to form micropores, and the colloidal liquid is further cured to form a firm coating layer, thereby finally obtaining the loose fibrilia coated by the thermosetting epoxy resin;

(4) and (3) adding the loose fibrilia obtained in the step (3), polycarbonate, ABS, an antioxidant, a lubricant and a flame retardant into a high-speed mixer, uniformly mixing, extruding by a screw extruder, water-cooling, bracing, granulating, screening and dehydrating to obtain the fiber-reinforced motorcycle helmet composite plastic.

Preferably, the steam explosion in the step (1) is a conventional treatment method for treating the fibrilia. The fibrilia is immersed in hot water to be fully softened, then the water is drained, the fibrilia is placed in a reaction vessel of a steam explosion device, the fibrilia is heated until the pressure in the reaction vessel rises to 1.0-1.5MPa, the pressure is maintained for 5min, and then the pressure is quickly released, so that the fibrilia is loosened to form micropores. The fibrilia has the characteristics of good toughening, strengthening and light weight, and is favorable for further loosening the fibrilia through steam explosion treatment, and the loosened fibrilia has good micropores and is very obvious in improving the buffering property of the material.

Preferably, the spraying amount of the foaming liquid in the step (1) is controlled to be 3-5% of the mass of the fibrilia. The loosened fibrilia micropores are easy to be filled and blocked by thermoplastic plastics, auxiliary agents and the like during the thermoplastic processing of plastics. For this reason, the present invention resides the blowing agent in the cells so that the hemp fibers still maintain good cells upon post-heat treatment.

Preferably, the colloidal liquid in the step (2) is liquid epoxy resin, pentaerythritol, toluene diisocyanate and a curing agent in a mass ratio of 40-50: 2-5: 1-3: 3-5, preparation; the liquid epoxy resin is bisphenol A type epoxy resin of Sanmu SM609-50, and the epoxy resin solution has low viscosity, good fluidity and easy spraying; the curing agent is dicyandiamide.

Preferably, the spraying amount of the colloidal liquid in the step (2) is based on uniformly coating the pretreated fibrilia; the preferred selection is that the spraying amount of the colloidal liquid is 5-10% of the mass of the pretreated fibrilia.

As a preferable technical scheme of the invention, the raw materials in the step (4) are as follows by weight: 10-15 parts of loose fibrilia, 40-60 parts of polycarbonate, 30-50 parts of ABS, 0.05-0.1 part of antioxidant, 0.5-1 part of lubricant and 0.5-2 parts of flame retardant.

Preferably, the polycarbonate in the step (4) is a Korean high-fluidity polycarbonate with LG model PC-201-22, which is advantageous for dispersing with hemp fiber; the antioxidant is prepared by mixing an antioxidant 1010 and an antioxidant 168 according to a weight ratio of 1: 2. The lubricant is at least one of stearic acid amide, paraffin, polyethylene wax and silicone powder.

As a preferred technical scheme of the invention, the temperature of the high-speed mixer in the step (4) is controlled to be 80-110 ℃, which is beneficial to melting and dispersing the lubricant; the screw extruder is a single screw extruder, and a double screw extruder is not recommended to be selected; the shearing force of the single-screw extruder is relatively weak, so that the light powder is prevented from being damaged by excessive shearing; the extrusion granulation temperature is controlled at 220-260 ℃.

Fiber reinforced plastics are well known in the art, and carbon fibers, glass fibers, etc. are uniformly applied to reinforced plastics. However, when used in helmet shell materials, it is critical how to achieve reinforcement while ensuring good cushioning and impact resistance of the plastic shell. We have attempted to foam helmet shell materials in a way that, despite the increased cushioning properties, the strength is greatly reduced. Aiming at the problems, the invention utilizes the characteristics of good toughening, strengthening and light weight of the fibrilia, is beneficial to further loosening the fibrilia through steam explosion treatment, the loosened fibrilia has good micropores, the foaming agent is placed in the micropores of the fibrilia, then thermosetting epoxy resin is coated, when the secondary fluidized bed is subjected to heat treatment, the built-in foaming agent generates gas to keep the micropores, meanwhile, the epoxy resin is heated and cured to form firm coating layer coated fibers, and the obtained fibers are loose fibrilia with micropores, as shown in figure 1. Because the thermosetting epoxy resin is not softened and melted in the later polycarbonate/ABS hot processing granulation process after being cured, the loose fibrilia micropores can be reserved in the final granulation process, and the obtained composite plastic has the functions of light weight and buffering while being reinforced. The helmet shell prepared from the material has high strength, light weight and buffering and energy-absorbing effects.

The invention further protects the fiber reinforced composite plastic for the motorcycle helmet, which is prepared by the method. The base material is a polycarbonate/ABS system, loose fibrilia is dispersed in the polycarbonate/ABS system, and the loose fibrilia is formed by coating the fibrilia with thermosetting epoxy resin.

Compared with the prior art, the fiber reinforced composite plastic for the motorcycle helmet and the preparation method thereof have the following beneficial effects:

(1) the fibrilia is loosened through steam explosion treatment, the loosened fibrilia has good micropores, a foaming agent is placed in the micropores of the fibrilia, then thermosetting epoxy resin is coated, when secondary fluidized bed heat treatment is carried out, the built-in foaming agent generates gas to keep the micropores, meanwhile, the epoxy resin is heated and cured to form firm coating layers to coat the fibers, and the obtained fibers are loose fibrilia with the micropores.

(2) The loose fibrilia obtained by the invention is protected by thermosetting resin, and the micropores of the fibrilia cannot be filled during the later granulation and thermoforming processes, so that better micropores can be reserved in the shell of the finished helmet. Endows the strength of the helmet shell and has excellent light weight and buffering property.

(3) After the thermosetting resin coats the fibrilia, the compatibility and dispersion in a fiber polycarbonate/ABS system are facilitated.

(4) The preparation method is simple in preparation process, low in cost and suitable for large-scale production.

In conclusion, the invention has the advantages and practical value, and the related publicly published technologies are not found in the prior art products, so that the invention has obvious progress compared with the prior art, is more practical and has wide large-scale popularization and production values.

Description of the drawings:

in order to more clearly illustrate the technical solution of the present invention, the technical idea of the present invention will be shown in a schematic manner below.

FIG. 1 shows that the present invention results in loose fibrilia coated with a thermosetting epoxy resin.

Wherein: 1-a thermosetting epoxy resin coating; 2-foaming loose fibrilia.

FIG. 2 is a flow chart of the preparation of the present invention.

The specific implementation mode is as follows:

the invention will now be further described by way of specific examples, with reference to FIGS. 1-2:

in order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.