阅读说明：本技术 一种自行车安全头盔用发泡复合材料及制备方法 (Foaming composite material for bicycle safety helmet and preparation method thereof ) 是由 张道增 于 2019-11-19 设计创作，主要内容包括：本发明属于头盔功能材料领域,具体涉及一种自行车安全头盔用发泡复合材料及制备方法。本发明将二氧化硅湿凝胶、聚醚、阿拉伯树胶粉形成的预混物分散在预反应的聚氨酯低聚物中,聚醚与低聚物进一步发泡反应,同时将湿凝胶、阿拉伯树胶均匀的分散在聚氨酯泡沫中,通过浸入聚乙二醇600吸附后,在聚氨酯泡沫中形成均匀的由二氧化硅、阿拉伯树胶、聚乙二醇600形成的非牛顿流体；该发泡材料使用时在平常具有良好的柔软性和缓冲性赋予良好的舒适感,但在遭受剧烈碰撞时,由于受快速冲击,复合发泡材料中的有二氧化硅、阿拉伯树胶、聚乙二醇600形成的非牛顿流体快速集聚由柔软变硬,从而使得头盔不易碎裂和刺穿,保护头部受伤。(The invention belongs to the field of helmet functional materials, and particularly relates to a foaming composite material for a bicycle safety helmet and a preparation method thereof. The invention disperses the premix formed by silica wet gel, polyether and arabic gum powder in the pre-reacted polyurethane oligomer, the polyether and the oligomer are further foamed and reacted, at the same time, the wet gel and the arabic gum are uniformly dispersed in the polyurethane foam, and after the wet gel and the arabic gum are immersed in polyethylene glycol 600 for adsorption, the uniform non-Newtonian fluid formed by silica, arabic gum and polyethylene glycol 600 is formed in the polyurethane foam; the foaming material has good softness and cushioning property at ordinary times to endow good comfort feeling when in use, but when in severe collision, the non-Newtonian fluid formed by silica, gum arabic and polyethylene glycol 600 in the composite foaming material is rapidly gathered and hardened by softness due to rapid impact, so that the helmet is not easy to crack and pierce, and the head is protected from being injured.)

1. A preparation method of a foaming composite material for a bicycle safety helmet is characterized by comprising the following steps: the preparation method comprises the following steps:

(1) adding tetraethoxysilane into a reaction kettle, then adding water and ethanol, adding hydrofluoric acid while stirring, adjusting the pH value of the solution to 3-4, stirring until tetraethoxysilane is completely hydrolyzed, filtering to obtain wet gel, and then adding polyether and Arabic gum powder to obtain a premix;

(2) pre-reacting a polyether and an isocyanate to form an oligomer with an isocyanate at a terminal; then adding the premix obtained in the step (1), a catalyst and a surfactant, uniformly stirring, and quickly adding a plate-shaped mould with the thickness of 5-10mm for foaming and shaping;

(3) and (3) drying the foamed material obtained in the step (2), immersing the dried foamed material into molten polyethylene glycol 600, adsorbing the polyethylene glycol 600, and cooling to obtain the foamed composite material for the bicycle safety helmet.

2. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: in the step (1), the mass ratio of the ethyl orthosilicate to the water to the ethanol is 1: 3-5:3-5.

3. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: stirring in the step (1) until the tetraethoxysilane is completely hydrolyzed and is controlled to be 1-2 h.

4. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: and (2) mixing the wet gel, the polyether and the Arabic gum powder in the step (1) according to the mass ratio of 10-15:20-25:5-10 to obtain a premix.

5. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: in the step (2), the mass ratio of the polyether to the isocyanate to the premix to the catalyst to the surfactant is as follows: 50:30-35: 50-60:0.1-0.2:0.5-1.

6. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: in the steps (1) and (2), polyether 330 is selected as the polyether.

7. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: in the step (2), the isocyanate is selected from one of isophorone diisocyanate, toluene diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.

8. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: in the step (2), the catalyst is one of dibutyltin dilaurate and stannous octoate.

9. The method for preparing a foamed composite material for a bicycle safety helmet according to claim 1, wherein: and (3) the surfactant in the step (2) is silicone oil.

10. A foamed composite material for a bicycle safety helmet, prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention belongs to the field of helmet functional materials, and particularly relates to a foaming composite material for a bicycle safety helmet and a preparation method thereof.

Background

The helmet is a head protection device mainly made of plastic and mainly comprises an outer shell, a lining, a suspension device and the like. Helmets are widely used in the construction industry, mining excavation, and sports fields. Particularly in the field of riding, such as cycling, helmets are required to be light and rigid. Both the shell and cushioning layer are required to protect the head and a light and comfortable feel is required. The existing helmet shell materials are generally divided into ABS engineering plastics, PC + ABS composite materials, glass fiber reinforced plastics, carbon fibers and the like, and the materials are required to have excellent heat resistance and weather resistance, excellent stability, wear resistance and impact resistance.

The buffer layer is attached to the inner part of the shell and mainly has the function of absorbing external impact force. The buffer layer mainly adopts white foaming styrene material and foaming polyurethane. However, the buffer layer is made of foam material, so that the strength and the extrusion resistance are poor. In practical use, the foam body has limited compressed deformation distance, and the formed buffering effect is not ideal under the action of larger impact force. In addition, the foam is generally of a low rigidity, which is not beneficial to the dispersion and the transmission of impact force, so that the impact force is excessively concentrated, and the head of a wearer still has the risk of injury. Upon a severe impact, the broken shell causes the cushioning layer to puncture, severely impacting head safety. In order to improve the safety performance of the helmet, the thickened outer shell is adopted for improvement at present. However, for a thickened helmet, the weight is increased, and the riding comfort is greatly reduced. There are also helmets with increased cushioning layer thickness, but too thick cushioning layers can make the helmet bulky and awkward.

Therefore, the development of new cushioning materials is particularly important to improve the comfort and safety of helmets. The prior art discloses attaching a layer of bubble pad between the outer shell and the lining foam cushion layer to assist in increasing the cushioning effect. However, the bubble pad is easily broken and loses the cushioning effect. non-Newtonian fluids are an intermediate material between solids and liquids and are of great value in the safety protection of helmets. The technical report is as follows: uk D3O developed a new gel material, a non-newtonian fluid with the dual properties of a liquid and a solid substance. It is a very soft, pliable gum when gently kneaded, but becomes very hard in the moment when hit strongly. The gel can be used on various helmets. Only provides a technical idea for further developing the safety and the comfort of the helmet.

However, there are few reports on how to make a non-newtonian fluid reasonable for use in helmets. Due to the special properties of the non-Newtonian fluid, the problems of precipitation, leakage and the like exist when the non-Newtonian fluid is used alone, and even if the non-Newtonian fluid is made into gel, the problem exists in how to be well combined with the buffer layer of the existing helmet.

Disclosure of Invention

In order to improve the safety and comfort of the bicycle helmet material, the invention provides a foaming composite material for a bicycle safety helmet and a preparation method thereof. The material is attached between the helmet shell and the buffer layer, rapidly gathers under the action of severe impact shearing, becomes hard from soft, absorbs impact energy, can prevent puncture, extrusion and the like during strong impact, and effectively protects the head.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a foaming composite material for a bicycle safety helmet is characterized by comprising the following steps: the preparation method comprises the following steps:

(1) adding tetraethoxysilane into a reaction kettle, then adding water and ethanol, adding hydrofluoric acid while stirring, adjusting the pH value of the solution to 3-4, stirring until tetraethoxysilane is completely hydrolyzed, filtering to obtain wet gel, and then adding polyether and Arabic gum powder to obtain a premix;

(2) pre-reacting a polyether and an isocyanate to form an oligomer with an isocyanate at a terminal; then adding the premix obtained in the step (1), a catalyst and a surfactant, uniformly stirring, and quickly adding a plate-shaped mould with the thickness of 5-10mm for foaming and shaping;

(3) and (3) drying the foamed material obtained in the step (2), immersing the dried foamed material into molten polyethylene glycol 600, adsorbing the polyethylene glycol 600, and cooling to obtain the foamed composite material for the bicycle safety helmet.

Further, the mass ratio of the ethyl orthosilicate, the water and the ethanol in the step (1) is 1: 3-5:3-5.

Further, stirring in the step (1) until the tetraethoxysilane is completely hydrolyzed for 1-2 hours.

Further, the wet gel, the polyether and the gum arabic powder in the step (1) are mixed according to the mass ratio of 10-15:20-25:5-10 to obtain a premix. Wherein the wet gel is a semi-dry wet gel that naturally filters out most of the water.

Further, in the step (2), the mass ratio of the polyether to the isocyanate, the premix, the catalyst and the surfactant is as follows: 50:30-35: 50-60:0.1-0.2:0.5-1.

Further, in the steps (1) and (2), polyether 330 is selected as the polyether.

Further, in the step (2), the isocyanate is selected from one of isophorone diisocyanate, toluene diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.

Further, in the step (2), the catalyst is one of dibutyltin dilaurate and stannous octoate.

Further, the surfactant in the step (2) is silicone oil.

The second object of the present invention is to provide a foamed composite material for a bicycle safety helmet, prepared by the above method. The foam material is directly cut and bonded in the shell layer of the bicycle helmet during use, and has an excellent buffering function. More remarkable functions are represented as follows: firstly, preparing wet gel of silicon dioxide, dispersing a premix formed by the wet gel, polyether and Arabic gum powder in a pre-reacted oligomer, further foaming and reacting the polyether and the oligomer, uniformly dispersing the wet gel and the Arabic gum in polyurethane foam, and forming non-Newtonian fluid formed by uniformly dispersing the silicon dioxide, the Arabic gum and the polyethylene glycol 600 in the polyurethane foam after the non-Newtonian fluid is absorbed by immersing the polyethylene glycol 600; the foaming material has good flexibility and buffering performance, and is directly cut and adhered to the inside of a helmet shell when being used as a bicycle helmet material. The foaming material has good softness and cushioning property at ordinary times to endow good comfort when in use, but when in severe collision, the non-Newtonian fluid formed by silica, gum arabic and polyethylene glycol 600 in the composite foaming material is rapidly gathered and becomes soft and hard due to high impact speed, so that the helmet is not easy to crack and pierce, and the head is protected from being injured.

It is known that the inner layer of the helmet shell is provided with a buffer layer, which can better protect the head when being slightly impacted, but when being strongly impacted, the buffer layer has an unobvious protection effect, and even the head is threatened by piercing and the like along with the fracture of the shell. The non-Newtonian fluid formed by the silicon dioxide, the gum arabic and the polyethylene glycol 600 is creatively and uniformly loaded in the foaming polyurethane to form the composite foaming material, and the material has good softness and buffering property under the common use condition; when the composite foam material is impacted by strong force, the non-Newtonian fluid in the composite foam material is rapidly gathered under the impact shearing action due to the high impact speed, becomes hard from soft, absorbs impact energy, can prevent puncture, extrusion and the like during strong impact, effectively protects the head, and is a safety helmet material with high practicability.

Compared with the prior art, the foaming composite material for the bicycle safety helmet and the preparation method have the following beneficial effects:

(1) by preparing wet gel of silicon dioxide, the wet gel, polyether and Arabic gum powder form a premix, so that when the premix is used as a reactant and is subjected to foaming reaction with pre-reacted oligomer, the polyether and the oligomer in the premix are subjected to foaming reaction under the action of a catalyst and moisture of the wet gel, and the wet gel and the Arabic gum are uniformly dispersed in polyurethane foam, so that uniform load dispersion is realized;

(2) after adsorbing the polyethylene glycol 600, the foaming polyurethane, silica (a dry product of wet gel) and gum arabic form a non-Newtonian fluid, the loading is firm, and the good softness and elasticity of the foaming material are kept during non-rapid impact; when the composite foam material is impacted by strong force, the non-Newtonian fluid in the composite foam material is rapidly gathered under the impact shearing action due to the high impact speed, becomes hard from soft, absorbs impact energy, can prevent puncture, extrusion and the like during strong impact, and effectively protects the head;

(3) the preparation treatment process is simple, has no special requirements on equipment, is easy to realize and is easy for large-scale production and popularization.

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

Detailed Description

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.