Fiber-reinforced composite plastic and method for producing the same

Abstract

The application discloses a kind of preparation methods of fiber reinforced composite plastics, comprising the following steps: S1 hydrogen peroxide / short glass fiber is added to ionic liquid, and after reaction, modified short glass fiber is obtained;S2 select amino phenyl boronic acid pinacol ester as intercalation guest, and with modified short glass fiber is reacted under nitrogen atmosphere, and phenyl boronic acid pinacol ester intercalation modified short glass fiber is obtained;S3 ultrafine glass fiber is dispersed in reactive surfactant, and mixed solution compounded by methyl methacrylate, initiator and anhydrous ethanol is added, and reaction is obtained modified ultrafine glass fiber;S4 after polybutylene terephthalate, auxiliary agent, modified short glass fiber and modified ultrafine glass fiber are extruded in extruder, fiber reinforced composite plastic is obtained.The composite plastic prepared by the application not only has excellent mechanical properties, but also has good flame retardant, heat resistance and wear resistance and other properties, and can meet the use requirements of power plug support.

Description

A fiber-reinforced composite plastic and its preparation method Technical Field

[0001] This invention relates to the field of plastics, and more particularly to a fiber-reinforced composite plastic and its preparation method. Background Technology

[0002] A power plug holder is a built-in accessory used to connect power cords. Three-prong integrated plug holders are typically injection molded, where the three copper contacts are integrally molded with the plastic bracket, significantly improving production efficiency. Plastic is a crucial component of the power plug holder, providing excellent support. Currently, power plug holders are generally made of polyvinyl chloride (PVC). However, due to PVC's low strength, it is prone to wear during actual use, and its strength is significantly lower than that of metal components, greatly reducing the lifespan of the plug holder. Furthermore, existing glass fiber reinforced plastics still have shortcomings in flame retardancy, heat resistance, and wear resistance, failing to meet the requirements for long-term use under harsh conditions. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides a fiber-reinforced composite plastic to solve the problems that existing glass fiber reinforced composite plastics cannot simultaneously meet the requirements of mechanical properties, flame retardancy, heat resistance and wear resistance, and thus cannot meet the long service life and safety of power plug bracket composite plastics under harsh conditions.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a fiber-reinforced composite plastic, the method comprising the following steps:

[0006] S1: A certain ratio of hydrogen peroxide / chopped glass fiber is added to an ionic liquid and reacted in an ultrasonic environment at 45-60℃ for a certain time. Then, it is repeatedly rinsed with deionized water and acetone until neutral to obtain modified chopped glass fiber. The hydrogen peroxide / chopped glass fiber ratio can be selected as 7-25 mL / g, preferably 10-15 mL / g; the reaction time can be selected as 30-120 min, preferably 60-90 min. The mass ratio of chopped glass fiber to ionic liquid is 20-50:100. The chopped glass fiber is alkali-free chopped glass fiber with a fiber diameter of 9-13 μm and a fiber length of 1-10 mm. This invention first swells the chopped glass fiber with a compounded ionic liquid, and then further softens the glass fiber under the oxidation of hydrogen peroxide. Combined with the strong dissolving ability of the ionic liquid, the surface and interior of the glass fiber undergo hydrophilic modification and hydroxylation treatment. The chopped fibers treated in step S1 are more easily dispersed in toluene in step S2, thus enabling efficient intercalation modification with aminophenylboronic acid pinacol ester on the fiber surface and inside.

[0007] S2: The modified chopped glass fibers obtained in step S1 are added to toluene solvent to obtain a modified chopped glass fiber toluene suspension; aminophenylboronic acid pinacol ester is selected as the intercalation guest, and at a certain aminophenylboronic acid pinacol ester / modified chopped glass fiber feed ratio, it is slowly added to the modified chopped glass fiber toluene suspension at 60-70°C under a nitrogen atmosphere, and then reacted at 95-105°C for a certain time to obtain phenylboronic acid pinacol ester intercalated modified chopped glass fibers; This invention utilizes the in-situ intercalation chemical reaction between the hydroxyl functional groups inside and on the surface of the chopped glass fibers and the aminophenylboronic acid pinacol ester intercalation guest molecules, thereby intercalating and modifying the surface of the chopped glass fibers with phenylboronic acid pinacol ester, which has good compatibility with polybutylene terephthalate. The high thermal degradation temperature of pinacol phenylboronic acid intercalated modified chopped glass fibers meets the melt blending and extrusion processing temperature requirements of polybutylene terephthalate (PET), significantly improving the dispersibility of chopped glass fibers within PET. Furthermore, the dioxane introduced into the pinacol phenylboronic acid structure effectively enhances the flame retardancy, heat resistance, and abrasion resistance of the composite plastic, while the introduction of the aniline structure further improves the dimensional stability and rigidity of the composite plastic.

[0008] S3: A certain amount of ultrafine glass fiber is uniformly dispersed in a reactive surfactant, and then a mixed solution of methyl methacrylate, initiator, and anhydrous ethanol is added. The mixture is heated to 60-80℃ to obtain modified ultrafine glass fiber. The diameter of the ultrafine glass fiber is less than 6μm, and the aspect ratio is 10:1-20:1. This invention performs organic modification of ultrafine glass fiber through chemical bonding. On the one hand, the reactive surfactant and methyl methacrylate undergo a cross-linking reaction under the action of an initiator. The introduction of acrylate improves the bonding force between the ultrafine glass fiber and the integrally injection-molded copper sheet, reducing problems such as cracking and detachment at the interface between the glass fiber reinforced polybutylene terephthalate composite plastic and the copper sheet. On the other hand, the rapid volatilization of anhydrous ethanol allows the organically modified ultrafine glass fiber to undergo micro-foaming, facilitating blending modification with pinacol phenylboronic acid intercalated modified chopped glass fiber, thereby improving the impact resistance and other mechanical properties of the composite plastic.

[0009] S4: Weigh 100 parts by weight of polybutylene terephthalate and 1.5-7.5 parts by weight of additives, mix them evenly, and place them in a twin-screw extruder. Add 5-15 parts by weight of the pinacol ester intercalated modified short-cut glass fibers obtained in step S2 and 15-25 parts by weight of the modified ultrafine glass fibers obtained in step S3 downstream of the extruder. The fiber-reinforced composite plastic is obtained through melting, mixing, extrusion, cooling, and drying. The temperature of each section of the twin-screw extruder is maintained at 200-250℃, the screw speed is 350-450 rpm, and the vacuum pump on the extruder controls the vacuum level inside the extruder to be higher than 0.06 MPa.

[0010] Preferably, the ionic liquid is obtained by compounding N-sulfonic acid butylpyridine trifluoromethanesulfonate and butylpyridine bromide in a molar ratio of 1:1 to 3.

[0011] Preferably, the aminophenylboronic acid pinacol ester is at least one selected from 4-aminophenylboronic acid pinacol ester, 3-amino-4-fluorophenylboronic acid pinacol ester, 4-(aminomethyl)phenylboronic acid pinacol ester, 3-aminophenylboronic acid pinacol ester, and 4-amino-2-fluorophenylboronic acid pinacol ester. As a further preferred embodiment, the aminophenylboronic acid pinacol ester is 3-amino-4-fluorophenylboronic acid pinacol ester or 4-amino-2-fluorophenylboronic acid pinacol ester. The introduction of fluorinated groups improves the aging resistance and heat resistance of the composite plastic.

[0012] Preferably, the reactive surfactant is prepared by a Schiff base reaction of 2,4-diallyloxy-6-amino-1,3,5-triazine and an aldehyde compound in a molar ratio of 1:1. This invention reacts 2,4-diallyloxy-6-amino-1,3,5-triazine with a long-chain aldehyde compound to obtain an active group with an allyloxy group. Simultaneously, the grafted long-chain alkane improves the impact resistance of the composite plastic, while the introduction of the triazine structure enhances the heat resistance and abrasion resistance of the composite plastic.

[0013] Preferably, the aldehyde compound is at least one of n-pentanal, hexanal, and n-heptanal.

[0014] Preferably, the additive is selected from at least one of nucleating agents, lubricants, and pigments. There are no particular limitations on the nucleating agents, lubricants, and pigments used in this application; those skilled in the art can add them according to actual needs.

[0015] Another aspect of the present invention is to provide a fiber-reinforced composite plastic, which is prepared by the fiber-reinforced composite plastic preparation method described above.

[0016] The beneficial effects of this invention are:

[0017] The composite plastic prepared by this invention, through the combination of chopped glass fibers and ultrafine glass fibers, not only significantly improves the strength of polybutylene terephthalate resin, but also improves the interlayer and interfacial properties between the glass fibers and polybutylene terephthalate resin. This avoids local delamination and cracking of the injection-molded power plug bracket composite plastic under load, thus preventing damage to the service life and safety of the power plug bracket.

[0018] The composite plastic prepared by this invention improves the interfacial compatibility between glass fiber and polybutylene terephthalate by intercalating and modifying short-cut glass fiber with pinacol phenylboronic acid ester. It also improves the flame retardancy, heat resistance and wear resistance of the composite plastic, so that the composite plastic can better meet the service life and safety requirements of power plug brackets under harsh conditions. Detailed Implementation Methods

[0019] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. Example 1

[0020] The method for preparing fiber-reinforced composite plastics in this embodiment includes the following steps:

[0021] S1: A certain ratio of hydrogen peroxide / chopped glass fiber is added to an ionic liquid and reacted in an ultrasonic environment at 60°C for a certain time. Then, it is repeatedly rinsed with deionized water and acetone until neutral to obtain modified chopped glass fiber. The hydrogen peroxide / chopped glass fiber ratio is 10 mL / g; the reaction time is 60 min; the ultrasonic frequency is 35 kHz; and the ultrasonic output power is 350 W. The mass ratio of chopped glass fiber to ionic liquid is 20:100. The chopped glass fiber is alkali-free chopped glass fiber with a diameter of 9–13 μm and a length of 1–10 mm. The ionic liquid is obtained by compounding N-butylpyridine trifluoromethanesulfonate and butylpyridine bromide in a molar ratio of 1:1.

[0022] S2: Add 25g of the modified chopped glass fiber obtained in step S1 to 100mL of toluene solvent to obtain a toluene suspension of modified chopped glass fiber; select 3-amino-4-fluorophenylboronic acid pinacol ester as the intercalation guest, and slowly add it to the modified chopped glass fiber toluene suspension at a certain 3-amino-4-fluorophenylboronic acid pinacol ester / modified chopped glass fiber feed ratio at 60℃ under a nitrogen atmosphere, and then react at 95℃ for a certain time to obtain phenylboronic acid pinacol ester intercalated modified chopped glass fiber; the mass ratio of 3-amino-4-fluorophenylboronic acid pinacol ester / modified chopped glass fiber is 1:1.8.

[0023] S3: By weight, 8 parts of ultrafine glass fiber are uniformly dispersed in 10 parts of reactive surfactant, and then a mixed solution composed of 5 parts of methyl methacrylate, 0.1 parts of initiator azobisisobutyronitrile and 1 part of anhydrous ethanol is added. The mixture is heated to 60°C to react and obtain modified ultrafine glass fiber. The diameter of the ultrafine glass fiber is less than 6 μm and the aspect ratio is 10:1 to 20:1.

[0024] S4: Weigh 100 parts by weight of polybutylene terephthalate, 1.5 parts by weight of talc and 1.5 parts by weight of pentaerythritol stearate, mix them evenly and place them in a twin-screw extruder. Add 5 parts by weight of pinacol phenylboronic acid ester intercalated modified chopped glass fiber obtained in step S2 and 15 parts by weight of modified ultrafine glass fiber obtained in step S3 downstream of the extruder. Obtain the fiber-reinforced composite plastic by melting, mixing, extrusion, cooling and drying.

[0025] The reactive surfactant was prepared by a Schiff base reaction of 2,4-dienepropoxy-6-amino-1,3,5-triazine and n-pentanal in a molar ratio of 1:1. Example 2

[0026] The method for preparing fiber-reinforced composite plastics in this embodiment includes the following steps:

[0027] S1: A certain ratio of hydrogen peroxide / chopped glass fiber is added to an ionic liquid and reacted in an ultrasonic environment at 60℃ for a certain time; then, it is repeatedly rinsed with deionized water and acetone until neutral to obtain modified chopped glass fiber; wherein, the hydrogen peroxide / chopped glass fiber feeding ratio is 12mL / g; the reaction time is 90min; the ultrasonic frequency is 40kHz; and the ultrasonic output power is 400W. The mass ratio of chopped glass fiber to ionic liquid is 35:100. The chopped glass fiber is alkali-free chopped glass fiber with a fiber diameter of 9-13μm and a fiber length of 1-10mm. The ionic liquid is obtained by compounding N-butylpyridine trifluoromethanesulfonate and butylpyridine bromide in a molar ratio of 1:2.

[0028] S2: Add 30g of the modified chopped glass fiber obtained in step S1 to 100mL of toluene solvent to obtain a toluene suspension of modified chopped glass fiber; select 4-amino-2-fluorophenylboronic acid pinacol ester as the intercalation guest, and slowly add it to the modified chopped glass fiber toluene suspension at a certain 4-amino-2-fluorophenylboronic acid pinacol ester / modified chopped glass fiber feed ratio at 70℃ under a nitrogen atmosphere, and then react at 105℃ for a certain time to obtain phenylboronic acid pinacol ester intercalated modified chopped glass fiber; the mass ratio of 4-amino-2-fluorophenylboronic acid pinacol ester / modified chopped glass fiber is 1:2.0.

[0029] S3: By weight, 12 parts of ultrafine glass fiber are uniformly dispersed in 11 parts of reactive surfactant, and then a mixed solution composed of 6 parts of methyl methacrylate, 0.1 parts of initiator azobisisobutyronitrile and 1.2 parts of anhydrous ethanol is added. The mixture is heated to 60°C to obtain modified ultrafine glass fiber. The diameter of the ultrafine glass fiber is less than 6 μm and the aspect ratio is 10:1 to 20:1.

[0030] S4: Weigh 100 parts by weight of polybutylene terephthalate, 1.5 parts by weight of talc and 3.5 parts by weight of ethylene bis-stearamide, mix them evenly and place them in a twin-screw extruder. Add 10 parts by weight of the phenylboronic acid pinacol ester intercalated modified chopped glass fiber obtained in step S2 and 20 parts by weight of the modified ultrafine glass fiber obtained in step S3 downstream of the extruder. The fiber-reinforced composite plastic is obtained by melting, mixing, extrusion, cooling and drying.

[0031] The reactive surfactant was prepared by a Schiff base reaction of 2,4-diallyloxy-6-amino-1,3,5-triazine and hexanal in a molar ratio of 1:1. Example 3

[0032] The method for preparing fiber-reinforced composite plastics in this embodiment includes the following steps:

[0033] S1: A certain ratio of hydrogen peroxide / chopped glass fiber is added to an ionic liquid and reacted in an ultrasonic environment at 50°C for a certain time. Then, it is repeatedly rinsed with deionized water and acetone until neutral to obtain modified chopped glass fiber. The hydrogen peroxide / chopped glass fiber ratio is 15 mL / g; the reaction time is 90 min; the ultrasonic frequency is 50 kHz; and the ultrasonic output power is 450 W. The mass ratio of chopped glass fiber to ionic liquid is 50:100. The chopped glass fiber is alkali-free chopped glass fiber with a diameter of 9–13 μm and a length of 1–10 mm. The ionic liquid is obtained by compounding N-butylpyridine trifluoromethanesulfonate and butylpyridine bromide in a molar ratio of 1:3.

[0034] S2: Add 35g of the modified chopped glass fiber obtained in step S1 to 100mL of toluene solvent to obtain a toluene suspension of modified chopped glass fiber; select 3-amino-4-fluorophenylboronic acid pinacol ester as the intercalation guest, and slowly add it to the modified chopped glass fiber toluene suspension at a certain 3-amino-4-fluorophenylboronic acid pinacol ester / modified chopped glass fiber feed ratio at 70℃ under a nitrogen atmosphere, and then react at 105℃ for a certain time to obtain phenylboronic acid pinacol ester intercalated modified chopped glass fiber; the mass ratio of 3-amino-4-fluorophenylboronic acid pinacol ester / modified chopped glass fiber is 1:1.9.

[0035] S3: By weight, 15 parts of ultrafine glass fiber are uniformly dispersed in 12 parts of reactive surfactant, and then a mixed solution composed of 7 parts of methyl methacrylate, 0.15 parts of initiator azobisisobutyronitrile and 1.5 parts of anhydrous ethanol is added. The mixture is heated to 80°C to obtain modified ultrafine glass fiber. The diameter of the ultrafine glass fiber is less than 6 μm and the aspect ratio is 10:1 to 20:1.

[0036] S4: Weigh 100 parts by weight of polybutylene terephthalate, 1.5 parts by weight of talc and 5.5 parts by weight of pentaerythritol stearate, mix them evenly and place them in a twin-screw extruder. Add 15 parts by weight of pinacol ester intercalated modified short glass fiber obtained in step S2 and 25 parts by weight of modified ultrafine glass fiber obtained in step S3 downstream of the extruder. Obtain the fiber-reinforced composite plastic by melting, mixing, extrusion, cooling and drying.

[0037] The reactive surfactant is prepared by Schiff base reaction of 2,4-dienepropoxy-6-amino-1,3,5-triazine and n-heptan in a molar ratio of 1:1.

[0038] Comparative Example 1

[0039] The preparation method of the fiber-reinforced composite plastic in this comparative example is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that in the preparation method of the composite plastic in this comparative example, the short glass fibers are not treated in step S1.

[0040] Comparative Example 2

[0041] The preparation method of the fiber-reinforced composite plastic in this comparative example is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that in the preparation method of the composite plastic in this comparative example, the short glass fibers are not treated in step S2.

[0042] Comparative Example 3

[0043] The preparation method of the fiber-reinforced composite plastic in this comparative example is basically the same as that in Example 1 in terms of raw material composition and preparation steps. The difference is that in the preparation method of the composite plastic in this comparative example, the ultrafine glass fiber is not treated in step S3.

[0044] The fiber-reinforced composite plastics prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, and the performance results are shown in Table 1:

[0045] Tensile properties are tested according to ISO 527-2; flexural properties are tested according to ISO 178; impact strength of simply supported beams is tested according to ISO 179; heat distortion temperature is tested according to ISO 75 with a load of 1.82 MPa; material flammability is tested according to UL-94; abrasion resistance is tested according to GB / T 3960 and evaluated by the coefficient of friction and wear mark width.

[0046] Table 1

[0047]

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a fiber-reinforced composite plastic, characterized in that, The preparation method includes the following steps: S1: A certain ratio of hydrogen peroxide / chopped glass fiber is added to an ionic liquid and reacted in an ultrasonic environment at 45-60℃ for a certain time; then, it is repeatedly rinsed with deionized water and acetone until neutral to obtain modified chopped glass fiber; the ionic liquid is obtained by compounding N-butylpyridine trifluoromethanesulfonate and butylpyridine bromide in a molar ratio of 1:1-3; S2: The modified chopped glass fiber obtained in step S1 is added to toluene solvent to obtain a modified chopped glass fiber toluene suspension; aminophenylboronic acid pinacol ester is selected as the intercalation guest, and at a certain ratio of aminophenylboronic acid pinacol ester / modified chopped glass fiber, it is slowly added to the modified chopped glass fiber toluene suspension at 60-70℃, and then reacted at 95-105℃ for a certain time to obtain phenylboronic acid pinacol ester intercalated modified chopped glass fiber; S3: A certain ratio of hydrogen peroxide / chopped glass fiber is added to an ionic liquid and reacted in an ultrasonic environment at 45-60℃ for a certain time to obtain phenylboronic acid pinacol ester intercalated modified chopped glass fiber; A certain amount of ultrafine glass fiber is uniformly dispersed in a reactive surfactant, and then a mixed solution of methyl methacrylate, initiator and anhydrous ethanol is added. The mixture is heated to 60-80°C to obtain modified ultrafine glass fiber. The reactive surfactant is prepared by Schiff base reaction of 2,4-diallyloxy-6-amino-1,3,5-triazine and aldehyde compound in a molar ratio of 1:

1. The aldehyde compound is at least one of n-pentanal, hexanal and n-heptanal. S4: 100 parts of polybutylene terephthalate and 1.5-7.5 parts of additives are weighed and mixed evenly and placed in a twin-screw extruder. 5-15 parts of pinacol ester intercalated modified chopped glass fiber obtained in step S2 and 15-25 parts of modified ultrafine glass fiber obtained in step S3 are added downstream of the extruder. The fiber-reinforced composite plastic is obtained by melting, mixing, extrusion, cooling and drying.

2. The method for preparing the fiber-reinforced composite plastic as described in claim 1, characterized in that, The chopped glass fibers are alkali-free chopped glass fibers with a fiber diameter of 9-13 μm and a fiber length of 1-10 mm.

3. The method for preparing the fiber-reinforced composite plastic as described in claim 1, characterized in that, The ultrafine glass fiber has a diameter of less than 6 μm and an aspect ratio of 10:1 to 20:

1.

4. The method for preparing the fiber-reinforced composite plastic as described in claim 1, characterized in that, The aminophenylboronic acid pinacol ester is at least one of 4-aminophenylboronic acid pinacol ester, 3-amino-4-fluorophenylboronic acid pinacol ester, 4-(aminomethyl)phenylboronic acid pinacol ester, 3-aminophenylboronic acid pinacol ester, and 4-amino-2-fluorophenylboronic acid pinacol ester.

5. The method for preparing the fiber-reinforced composite plastic as described in claim 1, characterized in that, The aminophenylboronic acid pinacol ester is 3-amino-4-fluorophenylboronic acid pinacol ester or 4-amino-2-fluorophenylboronic acid pinacol ester.

6. The method for preparing the fiber-reinforced composite plastic as described in claim 1, characterized in that, The additive is selected from at least one of nucleating agents, lubricants, and pigments.

7. A fiber-reinforced composite plastic, characterized in that, The composite plastic is prepared using the method for preparing fiber-reinforced composite plastic as described in any one of claims 1 to 6.

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