TWI875323B - A material formula of a carbon fiber, a manufacturing method and a steel-toed shoes thereof - Google Patents

Abstract

The present invention provides a manufacturing method of carbon fiber composite material at room temperature comprising: a. adding 5-10wt% carbon fiber powder to 30-60wt% thermal epoxy resin to form a premix; b. homogenizing the premix containing thermal epoxy resin under high shear force; c. reacting the homogenized premix with about 5-30 wt% PU prepolymer at room temperature to form a prepolymer; d. adding about 20-45wt% hardener, about 0.5-2wt% catalyst, and about 0.2-1wt% polymer defoaming agent to the prepolymer of step c to form a resin fiber composition, and e. applying the resin fiber composition of step d on a carbon fiber cloth to obtain a carbon fiber sheet. The present invention also comprises the carbon fiber composition and the product directly produced by the composition and the manufacturing method thereof.

Description

A carbon fiber composite material formula, processing method and fiber composite steel toe shoes made therefrom

The present invention relates to composite materials, in particular to a method for processing carbon fiber composite materials, and in particular to a method for processing a composite material of a prepreg that can be wet-cured at room temperature, a formula, and an article made of the composite material.

Carbon fiber material is a composite material with high mechanical strength and light weight. It can reduce the overall weight of the objects using carbon fiber materials while still having the characteristics of mechanical strength. In addition to the above advantages, thermoplastic carbon fiber plastics have the advantages of plastics in enhancing the complexity and functionality of the finished product. This fiber composite material is made of organic fibers through a series of heat treatments. It has the inherent characteristics of carbon materials and the softness and processability of textile fibers. It is a new generation of reinforcing fibers.

Thermoplastic composites (Fiber Reinforced Thermoplastic, FRTP) have high toughness, good impact resistance, short manufacturing cycle, excellent chemical resistance, low moisture absorption, easy storage of prepregs and no time limit, and repeatable processing. This material combines multiple advantages, allowing research teams in various countries to begin a series of studies on the matrix resin, reinforcement materials, process optimization, and different processing methods in thermoplastic composites.

The existing technology for making thermoplastic carbon fiber sheets has low production efficiency and cannot be recycled, which has always been the bottleneck that the fiber sheet manufacturing technology needs to overcome. When the formula used in the process contains epoxy resin as the main agent, the epoxy resin and the prepolymer must be pre-polymerized and mixed at a high temperature (such as 80-100 ° C) before other raw materials or additives can be added.

Since high-temperature mixing is required before processing can continue, and the formulated raw materials still need to be cured at high temperature after fiber impregnation before they can complete the B-Stage (semi-cured) prepreg sheet form for production and use, and the high-temperature oven continuous conveyor belt equipment required for mass production has high production and maintenance costs, as well as high electricity usage. Therefore, the traditional prepreg production method affects the overall process production efficiency, so there is still a need for further optimization. Formula raw materials that can quickly reach the B-Stage at low temperatures have extremely short pot-life and shelf-life, so they are not suitable for mass production, long-term storage or long-term process use. Therefore, the formula that combines fast low-temperature B-Stage curing and long shelf life is an important bottleneck in the current composite raw material formulation technology.

Therefore, the main purpose of the present invention is to provide a carbon fiber composite material processing method that can be painted at room temperature. The method is to impregnate the commercially available plain woven dry carbon fiber cloth in proportion by painting at room temperature. After rolling, the carbon fiber/epoxy prepreg can be quickly matured at room temperature (25-30°C) for about 3 hours, and the surface viscosity becomes colloidal. The semi-mature (B-Stage) carbon fiber/epoxy prepreg can be completed, and the process of transportation, bonding, cutting, etc. can be easily carried out.

To achieve the above-mentioned purpose, the composite material processing method provided by the present invention can be applied to the manufacture of carbon fiber composite steel toe shoes to reduce the weight of the steel toe shoes and provide appropriate anti-static protection.

The present invention provides a method for processing a carbon fiber composite material, comprising the following steps: a. Add 5-10% recycled carbon fiber powder to 30-60wt% thermosetting resin to form a first premix; b. Homogenize the first premix under high shear force; c. React the homogenized first premix with about 5-30 wt% PU prepolymer at room temperature to form a second prepolymer; d. Add about 20-45wt% hardener, about 0.5-2 wt% catalyst, and about 0.2-1wt% polymer defoaming agent to the second prepolymer in step c to form a resin fiber formula; and e. Apply the resin fiber formula of step d to a carbon fiber cloth to obtain a carbon fiber prepreg. After the prepreg is stacked, it can complete the rapid B-Stage aging at room temperature, and then the recycled carbon fiber sheet can be obtained after cutting.

Preferably, the thermosetting resin is an epoxy resin, a vinyl resin or an unsaturated polyester resin.

Preferably, the epoxy resin is bisphenol A type epoxy resin DGEBA (Diglycidyl Ether of Bisphenol-A), bisphenol F type epoxy resin DGEBF (Diglycidyl Ether of Bispheol-F), trifunctional epoxy resin TGPAP (Triglycidyl p-Aminophenol), tetrafunctional epoxy resin TGDDM (Tetraglycidyl Diaminodiphenylmethane); the vinyl resin is bisphenol A type vinyl resin BisGMA (Bisphenol-A Diglycidylmethacrylate) or phenolic vinyl resin Never (Novolac Vinyl Ester Resin).

Preferably, the catalyst is a tertiary amine catalyst, an imidazole catalyst, or a peroxide catalyst.

Preferably, the polymer defoaming agent is a silicone oil type or a non-silicone oil water-repellent polymer type structure.

Preferably, the PU prepolymer may be a mixture of diphenyl isocyanate, tolyl isocyanate, and terminal isocyanate prepolymer.

Preferably, the isocyanate terminated prepolymer structure comprises a finished product prepolymerized with diphenyl or tolyl isocyanate and a backbone structure of a polyol such as polyethylene glycol (PEG), polypropylene glycol (PPG), polytetrahydrofuran (PTG), polyester polyol (Polyester Polyol), polyether polyol (Polyether Polyol), polycarbonate polyol, etc., and may be a combination of isocyanate terminated prepolymer structures such as PEG/MDI, PEG/TDI, PPG/MDI, PPG/TDI, etc., and its NCO% value may be between 5% and 25%.

The present invention also relates to a carbon fiber composite material formula, which includes 5-10wt% carbon fiber powder, 30-60wt% thermosetting resin, 5-30wt% PU prepolymer, 20-45wt% hardener, 0.5-2wt% catalyst and 0.2-1wt% polymer defoamer.

The present invention also relates to a composite steel toe shoe, which is manufactured by further processing the carbon fiber sheet produced by the aforementioned steps.

From the above method and the processed product, it can be known that the present invention can be pre-polymerized at room temperature, and then processed by the known processing and molding method to obtain the final product. The pre-polymerized sheet is helpful to toughen the structure surface, and the target sheet still has a slightly curved shape at room temperature, which is beneficial to processing. And because it can react at room temperature, it can effectively save energy and is beneficial to industrial development.

In order to more clearly explain the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present invention. For ordinary technicians in this field, the present invention can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

The composite material processing method provided in a preferred embodiment of the present invention mainly provides a carbon fiber composite material processing method that can wet-mature prepreg at room temperature to facilitate the production of high impact-resistant recycled carbon fiber sheets and the application of the sheets.

It is understood that the term "wet aging" as used herein refers to a process in which the crosslinking and curing are gradually completed by reacting with moisture in the atmosphere.

It is understood that the "B-stage (semi-mature)" used herein refers to the state in which the thermosetting resin has hardened from a monomer (A-stage) to a linear and branched structure but has reached the gel point.

It is understood that the "recycled carbon" used herein refers to recycled carbon fiber powder obtained by various methods from various types of carbon fibers.

It is understood that the "PU prepolymer" used herein means a mixture of diphenyl isocyanate, tolyl isocyanate, and terminal isocyanate prepolymers. The terminal isocyanate prepolymer structure comprises a finished product prepolymerized with diphenyl or tolyl isocyanate and a polyol backbone structure such as polyester, polyether, polycarbonate, etc. It is possible to combine terminal isocyanate prepolymer structures such as PEG/MDI, PEG/TDI, PPG/MDI, PPG/TDI, etc., and the NCO% value thereof may be between 5% and 25%.

It is to be understood that "completing rapid B-Stage ripening" referred to herein means that the semi-ripening state can be completed at room temperature within 6 hours, preferably within 5 hours, more preferably within 4 hours, and more preferably within 3 hours, and the description of the semi-ripening state is the same as above.

It is understood that the "prepreg stack" referred to in this article refers to the carbon fiber cloth being coated with several layers of resin fiber formula. Preferably, in order to achieve the goal of lightweighting, the number of coating layers is 12-15 layers. The number of coating layers and the formula can be adjusted as needed.

In addition, the carbon fiber composite material processing method provided by the present invention has the following process sequence:

First, the recycled carbon fiber powder material that has been cleaned and surface-modified with silane is added to a thermosetting resin main agent in a formula ratio (about 5-10wt% recycled material) and stirred at 2500-4000 rpm until it is homogeneous. Then, a hardener, PU prepolymer, catalyst, and polymer defoamer are added in proportion to form a carbon fiber composite material formula, and then the formula is coated on a carbon fiber cloth to form a carbon fiber composite material.

Preferably, the high shear force is 3000 rpm.

Thermosetting resins are used in a proportion of 30-60 wt%. Bisphenol A epoxy resin DGEBA (Diglycidyl Ether of Bisphenol-A), bisphenol F epoxy resin DGEBF (Diglycidyl Ether of Bispheol-F), trifunctional epoxy resin TGPAP (Triglycidyl p-Aminophenol), and tetrafunctional epoxy resin TGDDM (Tetraglycidyl Diaminodiphenylmethane) can be used; vinyl resins include bisphenol A vinyl resin BisGMA (Bisphenol-A Diglycidylmethacrylate) and phenolic vinyl resin NVER (Novolac Vinyl Ester Resin).

The usage ratio of hardener is 20-45 wt%. The types of components are formulated according to the ratio of the main thermosetting resin types, and can use diamine hardeners such as polyetheramine or polyamide, anhydride hardeners such as nadic methyl anhydride NMA or methyl tetrahydrophthalic anhydride MTHPA, ethylene hardeners (Ethylene), styrene hardeners, etc.

Among them, the proportion of PU prepolymer is 5-30 wt%, and its ingredients are a mixture of diphenyl isocyanate, tolyl isocyanate, and terminal isocyanate prepolymer. The terminal isocyanate prepolymer structure includes a finished product prepolymerized with diphenyl or tolyl isocyanate and a polyol backbone structure such as polyester, polyether, polycarbonate, etc. The proportion of this material is determined according to the backbone molecular weight, type, and number of grafts. Taking the di-terminal isocyanate prepolymer as an example, the backbone molecular weight is short (such as MW=600 or less) and the backbone molecular weight is long (such as MW=2000 or more) and the backbone molecular weight is 20-30 wt%. Among them, the functional groups of the PU prepolymer (such as isocyanate NCO functional groups) react with the resin, and mature at low temperature at room temperature, without adhesion problems, and can be quickly cured (Curing), that is, mature to B-stage at room temperature; it can be non-adhesive (thickening, rapid partial curing) in about three hours, and then it can be placed in hot pressing for three or four days to be completely cured and fixed. In general, the present invention can be applied to different composite materials, including glass fiber cloth, glass fiber yarn bundle, carbon fiber cloth, carbon fiber yarn bundle, various non-woven fabrics, knitted blankets, etc.

The catalyst is used in a proportion of 0.5-2 wt%. It is added according to the type of hardener, and can be tertiary amine catalysts, imidazole catalysts, peroxide catalysts, etc. Those with general knowledge in the field can select appropriate catalysts according to the type of hardener. Catalysts are used to accelerate the speed of composite materials at medium and high temperatures and the stability of the mechanical properties of the product.

The usage ratio of polymer defoamer is 0.2-1 wt%. Silicone oil type or non-silicone oil water-repellent polymer structure can be used. The use of polymer defoamer is helpful to separate the gas phase impurities mixed with the resin in the room temperature wet aging step.

The resin obtained above can be impregnated into commercially available plain-woven dry carbon fiber cloth in proportion by brushing at room temperature. After being rolled up, it can be rapidly matured at room temperature (25-30°C) for about 3 hours, and the surface viscosity becomes colloidal, so that the carbon fiber/resin prepreg layer Shore A hardness> 60, and the semi-mature (B-Stage) carbon fiber/resin prepreg is obtained. The hardness is determined by the prepreg layer (sheet), and it can be easily transported, bonded, cut and other processes. In addition, the carbon fiber cloth used includes but is not limited to glass fiber, glass fiber bundle, carbon fiber cloth, carbon fiber bundle, carbon fiber powder, Kevlar cloth, Kevlar yarn bundle, various non-woven fabrics, needle-punched blankets, etc. The hardness of this prepreg (i.e., resin fiber mixture) reaches a aging balance after 5 hours, and can be stored at room temperature to maintain high-temperature hot pressing molding reactivity and material flexibility for about 4 days. The resin content of the prepreg is between 35-50%. This prepreg is then rolled and pressed after being stacked to a fixed number of layers to complete the recycling of carbon fiber composite sheets.

The finished recycled carbon fiber composite sheet can be cut into a fixed-size carbon fiber/epoxy resin molded preform by a hydraulic die cutter. The cutting size depends on the product to be processed. For example, the present invention can be applied to steel-toed safety shoes, and the size of the sheet is determined by the size of the shoe. Since the prepreg (i.e., the resin fiber mixture) is semi-mature, it can be placed directly in the mold and formed into a low-carbon carbon fiber composite steel-toed shoe by a 5-minute molding process at 150 to 170°C. The final product has good impact resistance and anti-static properties, and meets the anti-static safety shoe specifications of CNS20345.

Example 1: Hardness variation of carbon fiber sheet made of PU prepolymer disclosed in the present invention

As shown in Figure 1, the hardness change after prepreg treatment can reach the semi-mature (B-Stage) state within 4 hours at room temperature, which is conducive to the subsequent processing.

Example 2: Comparison of the impact resistance of the PU prepolymer modified composite material formula disclosed in this application

According to the test according to CNS20344-5.3.2.3, the finished shoe sample size is French 40, the original clay height is 20±2mm, and after the test it must be greater than 13.5mm. The test results are as follows: formula Unmodified formula This case formula bifunctional prepolymer This case formula trifunctional prepolymer 200J impact clay height (mm) 16.3 19.5 20.2

Example 3: Comparison of the conductivity of carbon fiber cloth mixed with recycled carbon fiber powder disclosed in this application

The test was conducted according to CNS20345-6.2.2.2. The results are shown in the following table. Material Stainless steel Glass fiber Carbon fiber cloth in this case Resistance(Ω) ~0 ∞ 3.66×10 ⁷ CNS20345 Shoe Grade ＜100 kΩ 1000MΩ＞x＞100kΩ Conductive shoes Insulation Anti-static shoes

From the table above, we can see that the carbon fiber cloth made in this case can effectively demonstrate the anti-static effect.

Example 4: Comparison of lightweight steel head made of fiber cloth produced in this application Material Weight(g) Weight loss (%) Stainless steel 106.44 - Glass fiber 58.02 -55 Carbon fiber cloth in this case 42.61 -40

As can be seen from the above table, the steel toe shoes made of the carbon fiber cloth in this case can effectively reduce the weight and increase the wearing comfort of the user.

Example 5: Hardness variation of the carbon fiber sheet produced by this application

Tested with Shore A hardness tester, the test results are shown in the following table Time(hr) 0 1 2 3 4 5 6 twenty four 48 72 144 Hardness Type A 38 44 50 55 63 65 67 72 75 87 87

Finally, it should be understood that the embodiments described in the present invention are intended only to illustrate the principles of the embodiments of the present invention. Other variations may also fall within the scope of the present invention. Therefore, as examples and not limitations, alternative configurations of the embodiments of the present invention may be considered consistent with the teachings of the present invention. Accordingly, the embodiments of the present invention are not limited to the embodiments explicitly introduced and described herein.

without

Figure 1 shows the hardening reaction of carbon fiber sheet.

Claims (10)

A method for processing a carbon fiber composite material comprises the following steps: a. adding 5-10wt% carbon fiber powder to 30-60wt% thermosetting resin to form a first premix; b. homogenizing the first premix under high shear force; c. reacting the homogenized first premix with about 5-30 wt% PU prepolymer at room temperature to form a second prepolymer, wherein the PU prepolymer is a mixture of diphenyl isocyanate, tolyl isocyanate and terminal isocyanate prepolymer; d. adding about 20-45wt% hardener, about 0.5-2 wt% catalyst, and about 0.2-1wt% and a high molecular weight defoaming agent to form a resin fiber mixture; and e. Applying the resin fiber mixture of step d to a carbon fiber cloth to obtain a carbon fiber sheet. The carbon fiber composite material processing method as described in claim 1, wherein the thermosetting resin is an epoxy resin, a vinyl resin or an unsaturated polyester resin. A carbon fiber composite material processing method as described in claim 2, wherein the epoxy resin is bisphenol A type epoxy resin DGEBA (Diglycidyl Ether of Bisphenol-A), bisphenol F type epoxy resin DGEBF (Diglycidyl Ether of Bispheol-F), trifunctional epoxy resin TGPAP (Triglycidyl p-Aminophenol) or tetrafunctional epoxy resin TGDDM (Tetraglycidyl Diaminodiphenylmethane); the vinyl resin is bisphenol A type vinyl resin BisGMA (Bisphenol-A Diglycidylmethacrylate) or phenolic vinyl resin Never (Novolac Vinyl Ester Resin). The carbon fiber composite material processing method as described in claim 1, wherein the catalyst is a tertiary amine catalyst, an imidazole catalyst or a peroxide catalyst. In the carbon fiber composite material processing method as described in claim 1, the polymer defoaming agent is a silicone oil type or a non-silicone oil water-repellent polymer structure. A carbon fiber composite material processing method as described in claim 1, wherein the hardness of the carbon fiber sheet after 3 hours in an environment of 25-30°C is Shore A 55 or above, and the hardness of the carbon fiber sheet from 24 hours to 48 hours in an environment of 25-30°C is Shore A 72 to Shore A 75. The carbon fiber composite material processing method as described in claim 1, wherein the terminal isocyanate prepolymer structure comprises a finished product prepolymerized from diphenyl or tolyl isocyanate and a polyol main chain structure such as polyester, polyether, polycarbonate, etc. The carbon fiber composite material processing method as described in claim 1, wherein the shear force ranges from 2500 to 4000 rpm. A carbon fiber composite material formula comprises 5-10wt% carbon fiber powder, 30-60wt% thermosetting resin, 5-30wt% PU prepolymer, 20-45wt% hardener, 0.5-2wt% catalyst and 0.2-1wt% polymer defoamer, wherein the PU prepolymer is a mixture of diphenyl isocyanate, tolyl isocyanate and terminal isocyanate prepolymer. A fiber composite steel toe shoe is made of a carbon fiber sheet made by the processing method described in any one of claims 1 to 8.

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