A modified fiber material and a method for modifying fiber materials

Abstract

This invention belongs to the field of material surface technology, and specifically relates to a modified fiber material and a method for modifying fiber materials. The method provided by this invention includes: Step 1, modifying the fiber using low-temperature plasma; Step 2, thoroughly impregnating the modified fiber from Step 1 in a mixture of a surface modifier and an amine curing agent; Step 3, curing the fiber by ultraviolet light irradiation to obtain the modified fiber material. This invention first treats the fiber surface with plasma, and then treats the fiber with a surface modifier, which improves the bonding strength between the fiber and the matrix resin, enabling the fiber to maintain a strong bond with the matrix resin over a long period.

Description

Technical Field

[0001] This invention belongs to the field of material surface technology, and specifically relates to a modified fiber material and a method for modifying fiber materials. Background Technology

[0002] Fibers (such as aramid fibers, carbon fibers, and basalt fibers) possess good mechanical properties and are often combined with matrix resins to prepare composite materials. However, due to the poor bonding strength between the fibers and the matrix resin, the fibers and matrix resin are prone to peeling, severely affecting the performance of the composite material. Many high-performance fibers (such as [fiber name missing]) have excellent overall properties, but their smooth surfaces result in poor bonding strength with the matrix resin, leading to poor mechanical properties in the composite material. To improve the interfacial bonding strength between the fiber material and the matrix resin, conventional epoxy adhesives are often added for bonding. However, because the crosslinking density of conventional epoxy adhesives increases after curing, it generates significant internal stress, making the prepared composite material brittle and lacking flexibility. This results in poor peel resistance, crack resistance, and impact resistance.

[0003] To address the above issues, current methods often involve treating the surface of the fiber material before bonding it to the matrix resin, which has yielded good results. These methods include chemical modification methods (such as surface etching, surface grafting, surface fluorine modification, and surface rare earth modification) and physical modification methods (such as gamma-ray radiation modification and ultrasonic impregnation modification). However, most of these methods remain at the laboratory stage and suffer from problems such as long processing time, low efficiency, and complex procedures.

[0004] Plasma surface treatment has been widely adopted in recent years for material surface treatment due to its high efficiency and other advantages. This method involves using plasma equipment to excite gas and generate active groups to attach these groups to the material surface, as illustrated in Chinese patent application CN87104425A. However, the active groups grafted onto the material surface have a time-sensitive effect; if they are not combined with the matrix resin within 48 hours, the fiber surface activation will cease, and the number of active groups on the surface will gradually decrease. This is because these active groups react with certain substances in the surrounding environment, causing them to decrease and eventually disappear. This means that after surface modification of the fiber material, it must be combined with the matrix resin as soon as possible, which will cause inconvenience to the use of the treated fiber material. Summary of the Invention

[0005] To address the above technical problems, this invention provides a modified fiber material and a method for modifying fiber materials, the specific technical solution of which is as follows:

[0006] A method for modifying fiber materials, comprising:

[0007] Step 1: Modify the fiber using low-temperature plasma;

[0008] Step 2: Thoroughly impregnate the modified fibers from Step 1 in a mixture of surface modifier and amine curing agent;

[0009] Step 3: Then, cure the material by irradiation with ultraviolet light to obtain the modified fiber material.

[0010] Specifically, the surface modifier mentioned in step 1 is a flexible thiol silane-modified bisphenol F epoxy acrylate.

[0011] Specifically, the preparation method of the flexible thiol silane-modified bisphenol F epoxy acrylate is as follows:

[0012] Bisphenol F epoxy acrylate was dissolved in toluene, a catalyst was added, and then the mixture was heated and stirred. Thiol silane was then added dropwise to react with the catalyst. After the reaction was completed, the mixture was distilled under reduced pressure to obtain flexible organosilicon-modified bisphenol F epoxy acrylate.

[0013] More specifically, the molar ratio of bisphenol F epoxy acrylate to toluene is 2-3:45;

[0014] More specifically, the catalyst is dibutyltin dilaurate;

[0015] More specifically, the molar ratio of the bisphenol F type epoxy acrylate to the catalyst is 100:0.5 to 2.

[0016] More specifically, the mass ratio of the bisphenol F epoxy acrylate to the thiosilicone is 1:1;

[0017] More specifically, the heating temperature during the heating and stirring process is 50-100°C, and the stirring speed is 100-400 rpm.

[0018] Specifically, the preparation method of the bisphenol F type epoxy acrylate is as follows:

[0019] Take bisphenol F epoxy resin, heat it, add a polymerization inhibitor, then pass nitrogen gas to remove oxygen, and after heating, add a mixture of n-butyl acrylate, glycidyl methacrylate and catalyst A dropwise. After the reaction, bisphenol F type epoxy acrylate is obtained.

[0020] More specifically, the heating is heating to a temperature of 55-65°C;

[0021] More specifically, the polymerization inhibitor is selected from p-hydroxyanisole, hydroquinone, and thiophene.

[0022] More specifically, the mass ratio of the bisphenol F epoxy resin, n-butyl acrylate, and polymerization inhibitor is 1–1.25: 2–2.5: 1;

[0023] More specifically, the nitrogen gas is introduced for deoxygenation for 30 minutes;

[0024] More specifically, the heating refers to raising the temperature to 75°C;

[0025] More specifically, the reaction temperature is 90–110°C, and the reaction time is 6–8 hours;

[0026] More specifically, catalyst A is selected from triphenylphosphine and tetrabutylammonium bromide;

[0027] More specifically, in the added mixture, the mass ratio of n-butyl acrylate to glycidyl methacrylate is 24-26:29, and the amount of catalyst A added is 1-3% of the total mass of the added bisphenol F epoxy resin, polymerization inhibitor, n-butyl acrylate and glycidyl methacrylate.

[0028] Specifically, the preparation method of the thiol silane is as follows:

[0029] (1) Mix dimethyldimethoxysilane, methyltrimethoxysilane, 3-(trimethyloxysilyl)-1-propanethiol and toluene, stir and heat, and then keep warm.

[0030] (2) After adjusting the pH value to 7, let it stand, and then remove the solvent and low-boiling-point residues in the organic phase to obtain a transparent liquid;

[0031] (3) After adding 3-(trimethyloxysilyl)-1-propanethiol and 3-bromopropene to a transparent liquid, the mixture is separated to obtain thiol silane.

[0032] More specifically, in step (1), the molar ratio of dimethyldimethoxysilane, methyltrimethoxysilane, and 3-(trimethyloxysilyl)-1-propanethiol is 29:15:25, and the molar ratio of dimethyldimethoxysilane to toluene is 1:15 to 20.

[0033] More specifically, in step (1) the heating and stirring process, the heating temperature is 50°C and the stirring speed is 300-500 rpm;

[0034] More specifically, the heat preservation time mentioned in step (1) is 60 minutes;

[0035] More specifically, in step (2), the pH value is adjusted using a hydrochloric acid solution with a mass fraction of 10%.

[0036] More specifically, the removal of the organic phase in step (2) is carried out at 100–120 °C and 2–3 kPa.

[0037] More specifically, the molar ratio of methyltrimethoxysilane added in step (1) to 3-(trimethoxysilyl)-1-propanethiol and 3-bromopropene added in step (3) is 1 to 2:5:5.

[0038] More specifically, the separation described in step (3) is centrifugal separation.

[0039] Specifically, the fiber mentioned in step 1 is selected from one or more of carbon fiber, aramid fiber and basalt fiber.

[0040] Specifically, the low-temperature plasma mentioned in step 1 includes N, O, and O3 plasma;

[0041] Specifically, in step 1, the time for modifying the fiber using low-temperature plasma is 10–30 seconds.

[0042] Specifically, the amine curing agent mentioned in step 2 is selected from any one or more of ethylenediamine, diethylenetriamine, or triethylenetetramine;

[0043] More specifically, the mass ratio of the amine curing agent to the surface modifier in step 2 is 1:18 to 20.

[0044] Specifically, the soaking time in step 2 is 20 to 30 seconds.

[0045] Specifically, the ultraviolet light irradiation time in step 3 is 2 to 3 minutes.

[0046] The present invention also provides a modified fiber material obtained by any of the above methods.

[0047] The present invention also provides a method for using the modified fiber obtained by any of the above methods, specifically as follows:

[0048] The modified fiber was compounded with the matrix resin at 100–150 °C, and then cooled to room temperature to obtain the composite material.

[0049] The matrix resin is a thermoplastic matrix resin or a thermosetting matrix resin;

[0050] The thermoplastic matrix resin includes polycarbonate, polyurethane, and polyetherimide;

[0051] The thermosetting resin includes phenolic resin and polyimide.

[0052] The method for generating low-temperature plasma in this invention involves activating, ionizing, or even decomposing N2, O2, etc., in an air atmosphere through dielectric barrier discharge, generating highly active plasmas such as O, O3, or N. These active particles act on the fiber surface, forming new oxygen- and nitrogen-containing active functional groups. These active functional groups increase the surface energy of the fiber, enabling the fiber to form stable covalent bonds with hydroxyl, ether, and ester bonds in the surface modifier, resulting in a strong bond between the fiber and the surface modifier.

[0053] The surface modifier provided by this invention has a lower viscosity, which is more conducive to fiber impregnation. Furthermore, the use of thiol silane modification gives the modified surface modifier flexibility, ultimately resulting in a flexible composite material. In addition, the surface modifier has good compatibility with the matrix resin and exhibits good bonding strength when combined with the matrix resin. The hydroxyl, ether, and ester groups it contains can further enhance the bonding strength with the matrix resin through strong intermolecular forces.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] This invention first treats the fiber surface with plasma, which gives the fiber and surface modifier a high bonding strength. After the fiber is treated with this method, the fiber can have a strong bonding ability with the matrix resin for a long time, effectively solving the time-related problem of traditional plasma surface treatment. Detailed Implementation

[0056] The present invention will be further described below with reference to specific embodiments. It should be understood that the embodiments provided are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of the present invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the claims of this application.

[0057] The method for preparing thiol silane of the present invention is as follows:

[0058] (1) Add 2.9 mol of dimethyldimethoxysilane, 1.5 mol of methyltrimethoxysilane, 2.5 mol of 3-(trimethyloxysilyl)-1-propanethiol and 58 mol of toluene to a 1000 mL three-necked flask, stir at 400 rpm and heat to 50 °C, and then keep warm for 60 min;

[0059] (2) Add hydrochloric acid solution to adjust the pH value of the mixture obtained in step (1) to 7. Then, under the condition of 120℃ / 3KPa, remove the solvent and low boiling point residue in the organic phase to obtain a transparent liquid.

[0060] (3) Add 5 mol of 3-(trimethyloxysilyl)-1-propanethiol and 5 mol of 3-bromopropene to a transparent liquid and then separate the thiol silane in a centrifuge.

[0061] The preparation method of bisphenol F type epoxy acrylate of the present invention is as follows:

[0062] 100g of bisphenol F epoxy resin was added to a reaction vessel, and 100g of polymerization inhibitor (thiophene) was added at 60℃. Nitrogen gas was purged for 30min to remove oxygen. When the temperature was raised to 75℃, a mixture of n-butyl acrylate (200g), glycidyl methacrylate (232g), and catalyst A (12.6g triphenylphosphine) was added dropwise. The mixture was reacted at 100℃ for 7 hours to obtain bisphenol F type epoxy acrylate.

[0063] Example 1

[0064] (1) The preparation method of the surface modifier in this embodiment is as follows:

[0065] Dissolve 100g of bisphenol F epoxy acrylate in 1500g of toluene, add 1g of dibutyltin dilaurate, stir at 70℃ for 5h at a stirring speed of 300rpm, and then slowly add 100g of the prepared thiol silane. After the reaction is completed, perform vacuum distillation to obtain the surface modifier.

[0066] (2) Methods for modifying fibers:

[0067] Step 1: Modify the carbon fiber to be treated using low-temperature plasma in an air atmosphere for 30 seconds.

[0068] Step 2: Take 100g of the surface modifier prepared in step (1), add 5g of amine curing agent and mix evenly, then add it to the carbon fiber after plasma treatment in step 1 to fully impregnate the carbon fiber.

[0069] Step 3: Then, the carbon fiber obtained in Step 2 is cured by irradiating it with ultraviolet light for 3 minutes to obtain the modified fiber material.

[0070] Example 2

[0071] The difference from Example 1 is that the modification of the fiber using low-temperature plasma in step 1 takes 20 seconds. All other features are the same as in Example 1.

[0072] Example 3

[0073] The difference from Example 1 is that the modification of the fiber using low-temperature plasma in step 1 takes 10 seconds. All other features are the same as in Example 1.

[0074] Comparative Example 1

[0075] The difference from Example 1 is that the carbon fibers to be treated are modified by low-temperature plasma in air for 30 seconds, without surface modifier treatment, to obtain the treated fibers. All other characteristics are the same as in Example 1.

[0076] Comparative Example 2

[0077] The difference from Example 1 is that the carbon fibers to be treated are simply impregnated in a surface modifier (flexible organosilicon-modified bisphenol F epoxy acrylate) without undergoing low-temperature plasma modification treatment to obtain the treated fibers. Other characteristics are the same as in Example 1.

[0078] Comparative Example 3

[0079] The difference from Example 1 is that only the binder (epoxy resin) is coated on the carbon fibers to be treated, without low-temperature plasma modification treatment, to obtain the treated fibers. Other characteristics are the same as in Example 1.

[0080] Performance testing

[0081] Then, the treated fibers from the examples and comparative examples were left to stand for 5 minutes and 48 hours, respectively, and then composited with polyurethane and polyimide at 120°C to obtain composite materials. The properties of the resulting composite materials were tested after standing for 20 minutes, and the results are shown in the table below:

[0082]

[0083]

[0084] The test results above show that the fiber treatment method of this invention results in a high bonding strength between the fiber material and the matrix resin. Furthermore, the fiber treated by this invention maintains a strong bond with the matrix resin even after a relatively long period (48 hours), making it easier to apply and solving the time-sensitivity problem caused by plasma treatment. In addition, the composite material prepared using the fiber treated in the comparative example of this invention has a larger bending radius before fracture, while the composite material prepared using the fiber treated in the example has a smaller bending radius before fracture. This indicates that the composite material prepared using the fiber treated by this invention can have better flexibility.

Claims

1. A method of modifying a fibrous material, characterized by, The application relates to a modified fiber material and a preparation method thereof. The preparation method comprises the following steps: 1, modifying the fiber by using low-temperature plasma; 2, fully immersing the modified fiber in a mixed solution of a surface modifier and an amine curing agent; 3, then irradiating and curing by using ultraviolet light, so that the modified fiber material is obtained. The surface modifier in the step 2 is flexible thiol silicane alkane modified bisphenol F epoxy acrylate, and the fiber is selected from one or more of carbon fiber, aramid fiber and basalt fiber. The preparation method of the flexible thiol silicane alkane modified bisphenol F epoxy acrylate is as follows: dissolving bisphenol F epoxy acrylate in toluene, adding a catalyst, then heating and stirring, then dropping thiol silicane alkane into the solution, and performing vacuum distillation after the reaction is completed, so that the flexible thiol silicane alkane modified bisphenol F epoxy acrylate is obtained. The molar ratio of the bisphenol F epoxy acrylate to toluene is 2-3:45; the molar ratio of the bisphenol F epoxy acrylate to the catalyst is 100:0.5-2; and the mass ratio of the bisphenol F epoxy acrylate to thiol silicane alkane is 1:

1. The preparation method of the bisphenol F epoxy acrylate is as follows: taking bisphenol F epoxy resin, adding a polymerization inhibitor after heating, then introducing nitrogen to remove oxygen, then dropping a mixed solution of n-butyl acrylate, glycidyl methacrylate and a catalyst after heating, and obtaining the bisphenol F epoxy acrylate after the reaction. The preparation method of the thiol silicane alkane is as follows: (1) mixing dimethyl dimethoxy silane, methyl trimethoxy silane, 3-(trimethyl oxysilyl)-1-propane thiol and toluene, stirring and heating, and then performing heat preservation treatment; (2) adjusting the pH value to 7, then standing, then removing the solvent and low-boiling-point residues in the organic phase, so that a transparent liquid is obtained; (3) adding 3-(trimethyl oxysilyl)-1-propane thiol and 3-bromo acrylate into the transparent liquid, and then performing separation, so that the thiol silicane alkane is obtained.

2. The method of modifying a fibrous material of claim 1, wherein, The modification time of the step 1 is 10-30s.

3. The method of modifying a fibrous material of claim 1, wherein, The amine curing agent in the step 2 is selected from any one or more of ethylenediamine, diethylenetriamine or triethylenetetramine. The mass ratio of the amine curing agent to the surface modifier in the step 2 is 1:18-20.

4. The method of modifying fibrous materials of claim 1, wherein, 8. A modified fiber material obtained by using the method in any one of claims 1-7. ​ ​ ​ 5. The method of modifying fibrous materials of claim 1 wherein, ​ 6. The method of modifying fibrous materials of claim 1 wherein, ​ 7. The method of modifying fibrous materials of claim 1 wherein, ​ ​

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