JP6547253B2 - Carbon fiber reinforced polyester resin and method of manufacturing injection molded product thereof - Google Patents

Description

  The present invention increases the melt viscosity and carbon fiber reinforced polyester by heating and mixing thermoplastic polyester (A), carbon fiber (B), multifunctional epoxy resin binder (C) and catalyst (D). The present invention relates to providing a method for producing a resin and then producing an injection-molded article having improved physical properties such as mechanical strength and corrosion resistance by an injection molding method.

Conventional thermoplastic polyesters are, for example, polyethylene terephthalate (hereinafter referred to as PET or pet) as aromatic saturated polyester, polybutylene terephthalate (PBT), polyethylene-2,6-naphthalenedicarboxylate (PEN), polycarbonate ( PC etc. They have physical properties excellent as transparency, mechanical strength, rigidity and the like as thermoplastic resins, and are widely used as fibers, films, plastics and the like. In particular, in the plastics field, molded articles are widely used for bottles, sheets, containers, daily necessities, automobile interior materials, machine parts, electric and electronic materials, construction materials, civil engineering materials, various industrial products and the like.
In addition, those polyesters are further used in higher-grade applications because their mechanical strength and heat resistance are improved by mixing glass fibers or carbon fibers to form thermoplastic composites. ing.
In particular, since glass fibers are inexpensive, a large amount of reinforced PET composites, PBT composites and PC composites are used. On the other hand, these polyester composites have been used only in small quantities for special applications because carbon fibers are high strength but too expensive.

  In recent years, in advanced industries such as civil engineering and construction, automobile industry, Shinkansen vehicle industry, aerospace industry, and linear motor car, including further weight reduction and energy saving by improving mechanical strength of constituent materials, Further performance improvement such as corrosion resistance, electrical characteristics, heat resistance and heat dissipation is required. Synthetic resins generally have improved physical properties and moldability if molecular weight is increased. However, polyester is difficult to obtain a high molecular weight due to the polycondensation method of its production method, and the solid phase polymerization method for increasing the molecular weight of the middle molecular weight polymer takes several hours and the productivity is low. . There was also a weakness that required large-scale facilities in petrochemical complexes.

As shown in Patent Document 1, Patent Document 2 and Patent Document 3, the present inventors adopt a reactive extrusion method using a medium molecular weight having a carboxyl group at the end of these polyesters, and employ an epoxy resin binder ( Depending on chain extenders, thickeners) and catalysts, polyesters are made to react with each other to realize high productivity of achieving high molecular weight in a few minutes or less, and manufacture by reactive extrusion using compact and inexpensive equipment Provided the law. However, while there has been a ground-breaking progress in moldability due to the increase in melt tension of polyester, on the other hand, the improvement of the mechanical properties has hardly seen the effect originally expected in the present invention.
It is known to mechanically mix carbon fiber with polyester to increase its mechanical strength and conductivity as a carbon fiber reinforced thermoplastic resin composite (CFRTP). However, these carbon fibers are generally produced by polymerizing polyacrylonitrile (PAN) -based polymer fibers by an ultra-high temperature baking method, and thus there are not many carboxyl groups or hydroxyl groups on the surface, so macroscopically dispersed in resin Do. However, since it is a foreign substance which does not melt in the resin, the interface between the two peels off when stress or impact is applied, which may embrittle the composite composition and, conversely, lower the strength. In order to improve the property, the carbon fiber surface is generally coated with a special epoxy resin to increase the affinity to the resin and improve the strength and the like of the composite material.
On the other hand, as shown in Patent Document 4, the inventor of the present invention is an epoxy resin binder (chain extender) and 10 parts by weight of vapor grown carbon fiber containing carbon nanotubes (CNT) in polyethylene terephthalate (PET) and Mixing by reactive extrusion in a twin-screw extruder in the presence of a catalyst has dramatically improved the tensile strength of the composite composition by 15-20% and the conductivity.
According to the example of Patent Document 5 disclosed recently, the carbon fiber aggregate obtained by firing only the thermosetting resin at 400 ° C. of the carbon fiber reinforced thermosetting resin composite material (CFRP) is further alkali-free It was opened by anodic oxidation of the electrolytic bath to recover regenerated carbon fibers. The tensile strength of the thermosetting resin composite material (CFRP) reinforced with 5% of this regenerated carbon fiber was hardly improved. However, the tensile strength of the sizing resin-treated 5% reinforced thermosetting resin composite (CFRP) was improved by about 20%. On the other hand, regenerated carbon fibers were recovered from carbon fiber reinforced carbon (C / C composite) by anodic oxidation of an acidic electrolytic bath. However, the description of the presence of the carboxyl group of the regenerated carbon fiber and the carbon fiber reinforced thermoplastic resin composite material (CFRTP) is not found.
According to Non-Patent Document 1, when the regenerated carbon fibers (long fibers) recovered from CFRP at 500-700 ° C. by the superheated steam method are analyzed by the Boehm method, mainly the phenolic hydroxyl group is about 0.1 equivalent / As many as Kg, the lactone group is as low as about 0.05 equivalent / Kg, and the carboxyl group is present only in a very small amount.
The epoxy resin binder (chain extender) and catalyst of the present invention react at high speed only with carboxyl groups and hardly react with hydroxyl groups and lactone groups.
In addition, as shown in Patent Document 6, the inventor of the present invention is an epoxy resin comprising polyethylene terephthalate (PET), 10 parts by weight of recycled carbon fiber and 2 to 5 cm long and 15-40 parts by weight of recycled carbon fiber and powder. Mixing by reactive extrusion in a twin-screw extruder in the presence of a system binder (chain extender) and a catalyst improves the tensile strength and their conductivity of the copolymer by about 2 times.

No. 3503952 publication International Publication WO2009 / 004745A1 Registered in the United States 8258239B2 Japanese Patent Application No. 2013-030429 JP, 2013-249386, A Japanese Patent Application No. 2014-24859

Materials on Plastic Recycling Chemistry, "Forefront of Recycling Technologies for CFRP" Presentation Material (2013.4.26) (Page 162-163, Fig. 23-25)

  The present invention includes further weight reduction and energy saving by improving the mechanical strength of constituent materials in the field of advanced industries such as civil engineering / building, automobile industry, Shinkansen vehicle industry, aerospace industry, linear motor car etc., The purpose is to further improve the performance such as corrosion resistance, conductivity, heat resistance and heat dissipation. In particular, it aims to develop applications such as lightweighting materials for high-rise buildings, high strength and corrosion resistant materials for coastal expressways, corrosion resistance and high strength materials for marine structures, and corrosion resistant materials for watercraft.

Means to try to solve the problem

  In the present invention, the thermoplastic polyester (A), the carbon fiber (B), the multifunctional epoxy resin binder (C), and the catalyst (D) are heated, mixed and subjected to a bonding reaction to increase the melt viscosity. The present invention provides a method for producing a carbon fiber reinforced polyester resin having improved moldability, and then producing an injection molded article having improved mechanical properties such as mechanical strength and corrosion resistance by an injection molding method.

More specifically, the present invention provides the following production method.
The present invention comprises, first, 100 parts by weight of polyester of component (A), 5 to 150 parts by weight of carbon fiber of component (B), and two or more epoxy groups in the molecule as a binder of component (C). High melt viscosity by heating a composition comprising 0.1 to 2 parts by weight of the multifunctional epoxy compound to be mixed and 0.01 to 1 part by weight of the reaction catalyst of the component (D) at a temperature above the melting point of the polyester The present invention also provides a method for producing a carbon fiber reinforced polyester resin, and a method for producing the same, which is characterized in that it is used as an injection molded body.

  The second aspect of the present invention is characterized in that the polyester of the component (A) contains at least one of polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and recycled products of the recovered molded articles thereof. It is an object of the present invention to provide a method for producing the carbon fiber reinforced polyester resin according to Item 1 and an injection-molded article thereof.

  In the present invention, the carbon fiber of the third component (B) is any one or more of the group consisting of recovered short fibers or powdered fibers of carbon fibers, short fibers of regenerated carbon fibers or powdered fibers And a method for producing the carbon fiber reinforced polyester resin according to claim 1 and its injection-molded article.

  In the fourth aspect of the present invention, the carbon fiber of component (B) is a carbon fiber short fiber or powdered fiber of an industrial product, a carbon fiber short fiber or powdered fiber of an electrochemically oxidized industrial product, or The carbon fiber reinforced polyester resin according to claim 1, characterized in that it contains at least one of short fibers or powdered fibers of chemically oxidized industrial products of carbon fibers, and an injection-molded article thereof. It provides a method.

  The fifth feature of the present invention is that the binder of the component (C) comprises, in combination, one or more multifunctional epoxy compounds having two or more epoxy groups in the molecule. It is an object of the present invention to provide a method for producing the carbon fiber reinforced polyester resin according to Item 1 and an injection-molded article thereof.

  The sixth aspect of the present invention is that the coupling reaction catalyst of the component (D) is an alkali metal carboxylate, an alkaline earth metal carboxylate, an alkali metal carbonate or bicarbonate, or an alkaline earth metal carbonate. A method for producing a carbon fiber-reinforced polyester resin and an injection-molded article thereof according to claim 1, which comprises at least one selected from the group consisting of salts and hydrogencarbonates.

  The seventh aspect of the present invention is a masterbatch based on a resin, wherein the binder of component (C) and the bond reaction catalyst of component (D) contain any one or more of the group consisting of non-crystalline polyester or polyolefin. The carbon fiber reinforced polyester resin according to claim 1, which is used in the form of (1), and a method for producing an injection-molded article thereof.

Effect of the invention

According to the present invention, the carboxyl group at the molecular terminal of the polyester is first formed in the presence of a catalyst in a chemical reaction involving cleavage of the epoxy ring of a multifunctional epoxy resin as a binder to form an ester bond containing a hydroxy group. It can be made into a large molecular weight polyester.
Next, the carboxyl group present on the surface of the carbon fiber and the carboxyl group at the molecular terminal of the polyester are newly hydroxylated by a chemical reaction involving the cleavage of the epoxy ring of a multifunctional epoxy resin as a binder in the presence of a catalyst. To form a large molecular weight polyester-carbon fiber copolymer. This coupling reaction can be carried out at high speed by means of a reactive extrusion process using a twin screw extruder. Since these bonding reaction polyester and polyester-carbon fiber copolymer have large molecular weight and long chain branched structure, the melt viscosity increases due to the "entanglement" effect of the molecular chain, and the conventional water blister to soft It becomes scaly, and injection moldability is dramatically improved.
Therefore, especially the mechanical strength is improved because the bond strength of the ester chain of the polyester / carbon fiber bonded reactant of the present invention is overwhelmingly larger than the intermolecular affinity of the conventional polyester / carbon fiber composition (blend). Ru. In addition, the introduction of carbon fiber also significantly improves other performances such as corrosion resistance, weather resistance, conductivity, heat dissipation, heat conductivity, heat resistance and oil resistance.
In the present invention, inexpensive recovered carbon fibers, regenerated carbon fibers from carbon fiber reinforced composite material (CFRP) of aircraft offcuts, and the like can be suitably used as raw materials.

Hereinafter, the present invention will be described in detail.
[Polyester of (A) component]
The polyester of the component (A) as the main raw material in the present invention is an aromatic saturated polyester, and a series of polyesters synthesized from a dicarboxylic acid component and a glycol component can be used. Examples of the dicarboxylic acid component include aromatic and alicyclic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and cyclohexane dicarboxylic acid. Among these, aromatic dicarboxylic acids, in particular terephthalic acid, isophthalic acid and 2,6-naphthalene dicarboxylic acid are preferred.
As a glycol component, ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, cyclohexane dimethanol etc. can be mentioned, for example. Among these, ethylene glycol and tetramethylene glycol (1,4-butanediol) are particularly preferred.
Specific examples of this series of polyesters include polyethylene terephthalate (PET), low melting point PET obtained by copolymerizing a small amount of isophthalic acid, copolymer of ethylene glycol, cyclohexane dimethanol and terephthalic acid (PETG), polytetramethylene terephthalate (poly Examples include butylene terephthalate, PBT), polyethylene-2,6-naphthalate (PEN) and the like. Polybutylene terephthalate (PBT) is preferred. Very inexpensive polyethylene terephthalate (PET) produced in large quantities is particularly preferred.
Moreover, as polyester of (A) component as a main raw material in this invention, the polycarbonate (PC; poly-4, 4'- isopropylene diphenyl carbonate) which uses bisphenol A as a main raw material as another thing of a series can be used.

  PET as a representative polyester which can be used in the present invention has an intrinsic viscosity of 0.50 dl / g or more as dissolved in a 1,1,2,2-tetrachloroethane / phenol (1: 1) mixed solvent and measured at 25 ° C. It is preferably (for fibers), more preferably 0.70 dl / g or more (for sheets), and still more preferably 0.80 dl / g or more (for bottles). If the intrinsic viscosity is less than 0.50 dl / g, the bonding reaction is also difficult according to the present invention, and the resulting polyester / carbon copolymer may not necessarily have excellent mechanical strength. The upper limit of the intrinsic viscosity is not particularly limited, but is usually 1.1 dl / g or less, preferably around 0.80 dl / g which is mass-produced for PET bottles and relatively inexpensive. The upper limit of the availability of commercially available PET is that the intrinsic viscosity is 1.25 dl / g, but the molding processability is deteriorated when used alone, so in the present invention the intrinsic viscosity is 0.60 to 0.80 dl / g. It is preferable to use it as a mixture.

[(B) component carbon fiber]
The carbon fiber of the component (B) in the present invention preferably has a carboxyl group. As carbon fibers having a carboxyl group, PAN-based industrial products having a carboxyl group can be used as a first series. For example, T008 series, T010 series, TS12-006 (cut length 3-12 mm), or MLD series of "Torayca" milled fibers (fiber length 30-150 μm) Etc. can be used as raw materials. Moreover, since these carbon fiber industrial products generally have a relatively small content of carboxyl groups, carboxyl groups, hydroxyl groups and acetyl groups are formed on the surface of carbon fibers by electrolytic oxidation treatment according to the method described in Patent Document 5. Depending on the introduction of groups and the like, they can be used in accordance with the object of the present invention.
Industrial products of pitch-based carbon fibers of Kureha Co., Ltd. and Osaka Gas Chemical Co., Ltd. can also be used as the second series. They have a relatively high content of carboxyl groups, but a rather low strength (with the advantage of isotropy).

The carbon fiber having a carboxyl group of the component (B) of the present invention can preferably use regenerated carbon fiber recovered from a carbon fiber-reinforced thermosetting epoxy resin composite (CFRP) as a third series. Carbon fiber reinforced thermosetting epoxy resin composite (CFRP), which is the raw material, is currently about 40% by-product by-product when assembling an aircraft, drill chips by-product during boring, fishing rods, golf tees, etc. Obtained from It is expected that in the future, a large amount will be derived from CFRP scrap, which accounts for about 65% of large aircraft.
In addition, cut fibers (cut lengths of 3 to 12 mm) of bobbin-wound long fibers recovered as an end product at the time of manufacturing an aircraft fuselage and the like can also be used favorably.
The regenerated carbon fiber has a large number of carboxyl groups introduced by electrolytic oxidation treatment under control of reaction conditions according to the description method of Sugiyama method of Patent Document 5, as exemplified in Production Example 1 of the Examples. The product can be used particularly preferably. The amount of carboxyl groups of the regenerated carbon fiber of the present invention usually contains the range of 0.01-0.20 mmol / g. The range which can be preferably used is 0.02-0.15 mmol / g.
The fiber length of the regenerated carbon fiber depends on the size of CFRP end material such as an aircraft and the size of chips from boring at the time of assembly. In the present invention, the fiber length is referred to as long fiber (100 mm or more), medium fiber (3 to 100 mm) or powdered fiber (3 mm or less). Any of them can be preferably used in the present invention.

[Binder of component (C)]
The binder of component (C) of the present invention preferably has a weight average molecular weight of 1,000 to 300,000, and is a polymer type polyfunctional epoxy compound containing 2 to 100 epoxy groups in the molecule. Can be used alone or as a mixture of two or more. Commercial products of high molecular weight resin-forming resin with pendant glycidyl group containing an epoxy ring and epoxy group in the molecule, such as “merproof” series from NOF Corporation, BASF You can use Japan's "John Krill ADR" series. As a resin to be a skeleton, an acrylic resin type or a styrene acrylic resin type is preferable to a polyolefin type (PP, PS, PE). Because the solubility parameters of the resin are raw material PET 10.7, epoxy resin 10.8, methyl polyacrylate 10.2, ethyl polyacrylate 9.4, polypropylene (PP) 9.3, poly ethyl methacrylate 9.0, polis scatter (PS) 8.9, polyethylene (PE) 8.0, and the closer the values, the better the mixing.
In addition, even if it is mixture of 1-2%, since the film * sheet of PET-type resin is made cloudy, it is not suitable when a molded article requires transparency. However, since the foam and the pipe or the 220 ° C. heat and oil resistant container are white, they can be used for applications which do not require such transparency and the black molded article of the present invention.

  The compounding quantity of the polyfunctional epoxy compound of (C) component is 0.1-5 weight part with respect to 100 weight part of polyester of (A) component. It depends greatly on the type of component (C) and the type and amount of carbon fiber in (B). In general, if the amount is less than 0.1 parts by weight, the effect of increasing the molecular weight and melt viscosity is insufficient, so that the molding processability is insufficient and the basic physical properties and mechanical properties of the molded article become inferior. If it exceeds 2 parts by weight, the molding processability is deteriorated to cause yellowing and coloring of the resin and by-products such as gel and fisheye (FE).

[Combination reaction catalyst of (D) component]
The bonding reaction catalyst as the component (D) in the present invention is composed of (1) organic acid salts, carbonates and hydrogencarbonates of alkali metals, and (2) organic acid salts, carbonates and hydrogencarbonates of alkaline earth metals. A catalyst containing at least one selected from the group consisting of As the organic acid salt, carboxylic acid salts, acetic acid salts and the like can be used, and among the carboxylic acid salts, especially stearic acid salts are preferred. As metals forming metal salts of carboxylic acids, alkali metals such as lithium, sodium and potassium; alkaline earth metals such as magnesium, calcium, strontium and barium can be used.
The compounding amount of the carboxylate as the binding reaction catalyst is 0.01 to 1 part by weight with respect to 100 parts by weight of the polyester of the component (A). In particular, 0.1 to 0.5 parts by weight is preferable. If the amount is less than 0.01 parts by weight, the catalytic effect is small, and the copolymerization reaction may not be completed, and the molecular weight may not be sufficiently increased. If the amount is more than 1 part by weight, gelation due to a local reaction or promotion of hydrolysis may cause troubles in the extruder due to a sharp rise in melt viscosity.

  In the present invention, the binder reaction of the component (C) and the bond reaction catalyst of the component (D) are in the form of a masterbatch based on a resin containing any one or more of the group consisting of non-crystalline polyester or polyolefin. Can be used. The example is illustrated in Production Example 2 of the example.

  The spreading agent of the present invention can be effectively used when the polyester of component (A) and the carbon fiber of component (B) are powders. Usually, paraffin oil, liquid paraffin, trimethylsilane or the like can be used. Liquid paraffin is particularly preferred as it is nonpolar, high boiling and moderately sticky fluid. These spreading agents are necessary for uniformly adhering the carbon fiber of the (B) component to the pellet or powder of the polyester of the (A) component, and the carbon fiber / powder scatters into the atmosphere and the human body It is an indispensable auxiliary agent that is necessary to prevent adverse effects on electrical instrumentation.

[Composition method, reactive extrusion method]
Next, the method of blending the polyester resin of the present invention will be described. The polyester of the component (A) may be in any form such as normal virgin pellets, recovered flakes, granules, powders, chips and the like. Generally, it is preferable to dry the main component polyester. The respective components are mixed by a mixer such as a tumbler or a Henschel mixer and then fed to an extrusion apparatus as a top feed method. Suitable when the carbon fiber is in powder form. The heating and melting temperature is preferably 250 ° C. or more and 300 ° C. or less of the melting point of the polyester from the viewpoint of the reactive extrusion method. In particular, the temperature is preferably 280 ° C. or less, particularly preferably 265 ° C. If the temperature exceeds 300 ° C., discoloration or thermal decomposition of the polyester may occur.
Apart from the above simultaneous mixing method, as a side feed method, reaction extrusion is carried out by supplying the polyester of component (A), the binder of component (C) and the catalyst of component (D) to a twin-screw extruder, The carbon fiber of the (B) component can be injected into the outlet portion of the shaft extruder to prevent the carbon fiber from being cut and produce a composite. It is suitable when the carbon fiber is a staple fiber.
As a reactive extrusion device, a single screw extruder, a twin screw extruder, a two-stage extruder of their combination, etc. can be used. Single screw extruders are inexpensive and suitable when the carbon fibers are in powder form. Twin screw extruders are expensive, but are suitable when the carbon fibers are staple fibers.

Next, the present invention will be described in detail based on examples. The evaluation methods for the polyester and polyester-carbon fiber composites of the present invention are as follows.
(1) Measuring Method of Intrinsic Viscosity (IV Value) of PET etc. It measured at 25 ° C. with a Canon Fensche viscometer using an equal weight mixed solvent of 1,1,2,2-tetrachloroethane and phenol. Or, we adopted the manufacturer's catalog value.
(2) Measuring method of melt flow rate (MFR) According to the conditions 20 of JIS K 7210, it measured on the conditions of the temperature of 280 degreeC, and the load of 2.16 kg. However, the resin used was one that had been hot-air dried or vacuum dried at 120 ° C. × 12 hours or 140 ° C. × 4 hours in advance.
(3) Measurement Method of Specific Gravity According to JIS K7112 method A (substitution method in water), the resin pellet was measured using alcohol as a liquid. Or it measured by the dimension measuring method of JIS K7222.
(4) Measurement method of mechanical strength Preparation of test piece: Molding temperature 270 ° C., mold temperature using injection molding machine SE18DUZ (clamping pressure 18 tons, screw diameter 16 mm) manufactured by Sumitomo Heavy Industries, Ltd. It shape | molded on the conditions of 35 degreeC and the cooling time 15-20 second.
Test piece shape: Tensile test piece JIS K7162 type 5A (thickness 2 mm)
Bending specimen strip type 80 mm × 10 mm (thickness 4 mm)
Tensile test: The tensile strength was carried out at a test speed of 2 mm / min and was evaluated by an average value of 3-5 points. Young's modulus was calculated by linear regression of 25% and 75% of the maximum load (JIS K7073 et al.).
Bending test: The bending strength was evaluated by performing 3-point bending at a test speed of 5 mm / min and averaging 3-5 points. The flexural modulus was calculated by linear regression of 25% and 75% of the maximum load (JIS K7074 et al.).
(5) Measurement Method of Carboxyl Group etc. Measured by Boehm method according to JIS K 0070. Sodium hydroxide and sodium hydrogen carbonate were individually added to a sample of carbon fiber or polyester, and back titration was performed using a hydrochloric acid solution using a potentiometric automatic measurement device. The total acid functional group content (total acid content) was determined by back titration with hydrochloric acid solution after sodium hydroxide addition, and the strong acid functional group content (carboxyl group content) by back titration by hydrochloric acid solution after sodium hydrogen carbonate addition. . The weakly acidic functional group content (phenolic hydroxyl group content) was determined from the total acid content-carboxyl group content. For example, the amount of carboxyl groups is 0.01-0.15 mmol / g on the surface of the carbon material of the battery negative electrode, and 0.04 or less mmol / g for the PET resin.

  The example of manufacture about the characteristic raw material concerning this invention is shown. The component (B), which is the main component of the present invention, preferably contains a carboxyl group for the adhesion to the polyester resin and the bonding reactivity with the modifier. A new industrial product also contains a carboxyl group, although the size is large.

Production Example 1

カルボキシル基は、新品炭素繊維には極めて微量にしか存在しないが、本発明の焼成後の再生炭素繊維には０．０３−０．０５ｍｍｏｌ／ｇも存在し、電解酸化後の再生炭素繊維にはその２−３倍の０．１０ｍｍｏｌ／ｇ にまで増加していた。尚、ＰＥＴ樹脂では０．０４以下ｍｍｏｌ／ｇであるので、本発明の再生炭素繊維のカルボキシル基量は共重合させるに充分である。(B) Component [Production example and analysis example by electrolytic oxidation of alkali liquid of regenerated carbon fiber containing carboxyl group]
According to Patent Document 7 (Japanese Patent Application Laid-Open No. 2013-249386), approximately 30 kg of CFRP offcuts by-produced at the time of aircraft assembly is cut into 10 cm square or less, and a thermosetting epoxy resin portion at 400-500 ° C. with an electric furnace Were removed by firing to obtain about 15 kg of regenerated carbon fibers (consolidated bodies).
5 g of regenerated carbon fibers (consolidated body) was put in a 500 cc beaker and immersed in 200 mL of a 0.1 mol / L aqueous solution of sodium hydroxide. The regenerated carbon fiber aggregate side was an anode, and the cathode side was a titanium electrode. The direct current electrolytic reaction was carried out at 3 V × 0.5 A for 1 hour. The regenerated carbon fibers opened by this electrolytic oxidation treatment were washed with water until neutral, dried and stored. This was repeated three times.
1 g of regenerated carbon fibers was weighed in each 200 cc Erlenmeyer flask, and immersed in 50 mL each of 0.1 mol / L aqueous sodium hydroxide solution or aqueous sodium hydrogen carbonate solution. After plugging, the two were placed in a permeator for 24 hours. 5 mL of supernatant liquid of each container was titrated with 0.05 mol / L hydrochloric acid aqueous solution, and the total acid amount and the carboxyl group amount were identified. The analysis according to the Boehm method is also performed on regenerated carbon fibers after firing and new carbon fibers, and the results are shown below in comparison.

The carboxyl group is present in a very small amount in the new carbon fiber, but 0.03-0.05 mmol / g is present in the regenerated carbon fiber after firing of the present invention, and the regenerated carbon fiber after electrolytic oxidation is present It has increased to 2-3 times 0.10 mmol / g. In addition, since it is 0.04 or less mmol / g in PET resin, the amount of carboxyl groups of the regenerated carbon fiber of this invention is enough to copolymerize.

  About 1 kg of the regenerated carbon fiber aggregate obtained above was placed in a 10 L electrolytic cell, and a potassium hydroxide aqueous solution was applied. This regenerated carbon fiber aggregate was used as a copper anode side, and the cathode side was used as a titanium electrode, and a low current, low voltage direct current electrolytic reaction was carried out for 4 hours. Most of the regenerated carbon fiber aggregate was opened, but it was mechanically opened to obtain regenerated black carbon fiber. The fiber length was 5 to 10 cm. The regenerated carbon fiber containing about 50% alkaline water was neutralized with an acid solution, washed with water and then dried overnight at 180 ° C. and stored. The same operation was repeated several times to produce 5 kg of regenerated carbon fibers.

Production Example 2

Component (C) and Component (D) [Example of Production of Modifier Masterbatch Used for PETG Substrate of Component (C) and Component (D)]
The modifier masterbatch is usually composed of a one-to-one blend of the pellets for the binder masterbatch of component (C) and the catalyst masterbatch of component (D).
[1] Preparation Example of Binder Masterbatch of Component (C) As a binder, as a representative example of a polyfunctional epoxy compound containing two or more epoxy groups in the molecule, “Merproof G- of NOF Corporation” "0130SP" (epoxy number 10 / number average molecular weight, number average molecular weight 5,500, epoxy equivalent 530 g / eq.) Is employed, and Eastman's non-crystalline copolyester "Eastar PETG 6763" is used as a base resin. did.
First, 15 parts by weight (15 kg, white powder) of MERPROOF G-0130SP as a binder for the component (C), 50 parts by weight (50 kg) of ground white powder of PETG 6763 as a base resin, and transparent pellets 50 of PETG 6763 115.1 Kg of formulation (50 Kg) and 0.1 part (0.10 Kg) of liquid paraffin as spreading agent were mixed in a Henschel mixer. Using the same direction twin screw extruder (screw diameter 70 mm, L / D = 32, 2-vent type) manufactured by Toshiba Machine Co., Ltd., which transferred this to the hopper on the extruder, set the temperature of cylinder and die Was 100-220 ° C. and a screw rotation speed of 160 rpm, and 115 kg of the formulation was top-fed from the hopper through a volumetric feeder. The resin pressure of the strand mold was 4.9-5.0 MPa, and the strand from the mold outlet to the water bowl was linear and stable, and the discharge rate was 117 kg / h.
The warm white pellet A agent (the binder masterbatch of the component (C)) was immediately transferred to a Hopper at 70 ° C., fluid-dried overnight, and then stored in a paper-aluminum-polyethylene triple-layer moisture-proof bag. The yield was 107 Kg.

[2] Preparation Example of Catalyst Masterbatch of Component (D) 10 parts by weight (10 Kg) of a composite catalyst consisting of 50% calcium stearate, 25% lithium stearate and 25% sodium stearate as a representative example of a catalyst for binding reaction Blend of 50 parts by weight (50 kg) of ground white powder of PETG 6763 as base resin, 50 parts by weight (50 kg) of transparent pellets of PETG 6763 and 0.2 parts by weight of liquid paraffin (0.20 kg) as spreading agent 110.2 kg was mixed with a Henschel mixer. This was transferred to the hopper on the extruder. Extrusion was carried out in substantially the same manner as described above. The resin pressure of the strand mold was 7.1-9.6 MPa, and the white strand from the mold outlet into the water bowl was linear and stable, and the discharge rate was 200 kg / h.
The warm white pellet B agent (catalyst masterbatch of component (D)) was immediately transferred to a Hopper at 70 ° C. and fluidized overnight, and then stored in a paper-aluminum-polyethylene triple-layer moisture-proof bag. The yield was 102 Kg.
100 kg of binder master batch A agent of component (C) and 100 kg of catalyst master batch B agent of component (D) were blended one-to-one to prepare 200 kg of modifier master batch.

[Production of a carbon fiber-reinforced pet resin pellet R1 comprising a pet resin, about 15% of recovered carbon fiber chops, and a modifier master batch and a production example of an injection-molded product]
100 parts by weight of commercial PET (PET) resin (general-purpose bottle grade: pellet of IV value 0.80) as polyester of component A (120 kg; moisture content after hot air drying at 120 ° C. for 12 hours about 100 ppm) and modification 6 parts by weight of the agent masterbatch (MB: PETG substrate) (7.2 kg; 0.45 parts by weight of a multifunctional epoxy resin as a combination of component C, 0.30 parts by weight of a combination reaction catalyst of component D) with a tumbler And mixed for 30 rpm x 10 minutes. These were delivered to the first hopper.
The recovered carbon fiber chops (the collected products of the bobbin-wound PAN-based carbon fibers collected as the B component carbon fibers and cut into 6 mm lengths, 40 kg) were delivered to the second hopper.
Using the same direction twin screw extruder (ZE40E: screw diameter 42 mm, L / D = 38) manufactured by Verstorf of Germany, the set temperature of cylinder and die consisting of 10 blocks of this extruder is 150-270 ° C and screw The recovered carbon fiber chops were continuously injected into the fifth block at a rotational speed of 100 rpm.
Using a gravimetric weighing single-shaft feeder, mixed resin pellets of A component, C component and D component from the first hopper at a speed of 18.02 Kg / h and 3.0 Kg / sec of carbon fiber chops collected from the second hopper The extruder was charged at a speed of h (carbon fiber content 14.3%).
Three strands of the strand were continuously extruded into water from a diagonally downward nozzle with a bore of 3 mm, and cut with a rotary cutter at a take-up speed of 20 m / min to produce a black resin pellet R1. The resin pressure of the strand mold was 0.90 to 1.2 MPa, and the strand from the mold outlet to the ladle was linear and the melt tension increased.
The warm black resin pellet R1 was immediately hot-air dried at 120 ° C. overnight and then stored in a paper-aluminum-polyethylene triple-layer moisture-proof bag. The yield was 20.6 Kg. The shape was cylindrical and about 2.5 mm in diameter × about 4.5 mm in length. Moreover, MFR (280 degreeC, 2.16 kg of loads) was 35 g / 10min.

The black pellet R1 of this carbon fiber reinforced pet resin is redried under vacuum and molded using an injection molding machine SE18DUZ (clamping pressure 18 tons, screw diameter 16 mm / SL screw) manufactured by Sumitomo Heavy Industries, Ltd. It is possible to mold the following injection molded body under the conditions of temperature 270-280 ° C, mold temperature 37-38 ° C, injection pressure 64-70 MPa, injection speed 20 mm / s, screw rotation speed 100 rpm and cooling time 15 seconds. done.
Injection molded product shape: For tensile test pieces JIS K7162 type 5A (thickness 2 mm)
Also, using the same molding apparatus, it was possible to mold the following injection molded body under almost the same conditions, but under the conditions of injection pressure 115-123 MPa and cooling time 20 seconds.
Shape of injection molded body: Strip type for bending test piece Length 80 mm × width 10 mm (thickness 4 mm)
Both showed good injection moldability without burr by-product.
The carbon fiber-reinforced pet resin pellet P1 had a tensile strength of 120 MPa, a Young's modulus of 4.0 GPa, a flexural strength of 194 MPa, and a flexural modulus of 8.1 GPa.
Compared with the transparent pellet P1 of only the PET resin of Comparative Example 1, the mixing effect of carbon fiber of about 15% in this example R1 is: tensile strength 2.0 times, Young's modulus 2.1 times, bending strength 2. It was 3 times and the flexural modulus was 3.9 times. An injection molded body is obtained which has a significantly improved mechanical strength.

[Production of a carbon fiber-reinforced pet resin pellet R2 comprising a pet resin, about 30% of recovered carbon fiber chops, and a modifier master batch and a production example of an injection-molded product]
Production of pellet R2 was carried out under substantially the same conditions as in Example 1. However, in order to make the content of the recovered carbon fiber chop about 30%, the feed rate was doubled and the feed rate of the pet resin was decreased.
100 parts by weight of a commercial PET (PET) resin (general-purpose bottle grade: pellet of IV value 0.80) as polyester of component A (120 kg; moisture content after hot air drying at 120 ° C. for 12 hours) Modifier master batch (MB: PETG substrate) 6 parts (7.2 Kg; 0.45 parts by weight of a multifunctional epoxy resin as a combination of component C, 0.30 parts by weight of a combination reaction catalyst of component D) with a tumbler The mixture was mixed at 30 rpm for 10 minutes using These were delivered to the first hopper. The recovered carbon fiber chops (the collected products of the bobbin-wound PAN-based carbon fibers collected as the B component carbon fibers and cut into 6 mm lengths, 40 kg) were delivered to the second hopper.
A 10-block cylinder and die setting temperature of this extruder is 150-270 ° C and using a twin screw extruder (ZE40E: screw diameter 42 mm, L / D = 38) manufactured by Verstorf, Germany. The screw speed was 150 rpm, and the recovered carbon fiber chops were continuously injected into the fifth block.
Using a gravimetric weighing single-axis feeder, mixed resin pellets of A component, C component and D component from the first hopper at a speed of 14.84 Kg / h, and carbon fiber chops recovered from the second hopper at 6.0 Kg / h The extruder was charged at a speed of h (carbon fiber content 28.8%).
Three strands of the strand were continuously extruded into water from a diagonally downward nozzle with a bore of 3 mm, and cut with a rotary cutter at a take-up speed of 20 m / min to produce a black resin pellet R2. The resin pressure of the strand mold was 1.1 to 1.2 MPa, and the strand from the mold outlet to the ladle was straight and melt tension increased.
The warm black resin pellet R2 was immediately hot-air dried at 120 ° C. overnight and then stored in a paper-aluminum-polyethylene triple-layer moisture-proof bag. The yield was 65 Kg. The shape was cylindrical and about 3 mm in diameter × about 5 mm in length. Further, MFR (280 ° C., load 2.16 kg) was 25 g / 10 min.

The black pellet R2 of this carbon fiber reinforced pet resin is redried under vacuum, and implemented using an injection molding machine SE18DUZ (clamping pressure 18 tons, screw diameter 16 mm / SL screw) manufactured by Sumitomo Heavy Industries, Ltd. The following injection molded article could be molded under substantially the same conditions as in Example 1 but under the condition of injection pressure of 116 to 121 MPa.
Injection molded product shape: For tensile test pieces JIS K7162 type 5A (thickness 2 mm)
Further, using the same molding apparatus, the following injection molded product could be molded under substantially the same conditions as Example 1, but under the injection pressure of 120-12 4 MPa.
Shape of injection molded body: Strip type for bending test piece Length 80 mm × width 10 mm (thickness 4 mm)
Both showed good injection moldability without burr by-product.
The carbon fiber-reinforced pet resin pellet P2 had a tensile strength of 144 MPa, a Young's modulus of 9.5 GPa, a flexural strength of 232 MPa, and a flexural modulus of 14.2 GPa.
Compared with the transparent pellet P1 of only the PET resin of Comparative Example 1, the mixing effect of about 30% of the carbon fiber in this example R2 is: tensile strength 2.4 times, Young's modulus 5.0 times, bending strength 2. It was 8 times and flexural modulus 6.8 times. An injection molded body is obtained, whose mechanical strength is further significantly improved.

Comparative Example 1

[Manufacture of pellet P1 only with PET resin]
100 parts by weight (3 kg) of PET resin of component A (pellets of commercial general-purpose products for PET bottles: IV value 0.80, MFR 35 g / 10 min) were used, and pellets were produced under substantially the same extrusion conditions as in Example 1. P1 was produced to obtain 2.9 Kg of transparent pellets. The strands bowed from the die exit to the water surface and meandered in the basin indicating low melt tension. The transparent pellet P1 was cylindrical and had a diameter of about 3 mm and a length of about 5 mm. Further, MFR (280 ° C., load 2.16 kg) was 57 g / 10 min. This melt viscosity is not suitable for injection molding.
This PET resin-only pellet P1 was injection-molded to form a tensile test piece and a bending test piece, which had a tensile strength of 59 MPa, a Young's modulus of 1.9 GPa and a flexural strength of 84 MPa, and a flexural modulus of 2.1 GPa.

[Production example of thick plate-like injection molded product from carbon fiber reinforced pet resin pellet R2 consisting of pet resin, recovered carbon fiber chops 30% and modifier masterbatch and cutting test of thick plate]
A black pellet R2 of the dried carbon fiber reinforced pet resin of Example 2 is molded using a hybrid injection molding machine FNX 140 (clamping pressure 140 tons) manufactured by Nisshin Resin Co., Ltd., at a molding temperature of 280 ° C., a mold The following plate-like injection molded article was prepared under the conditions of a temperature of 135-145 ° C., an injection peak pressure of 24 MPa, a filling speed of 30 mm / sec, a screw rotation speed of 60 rpm and a cooling time of 32 seconds (67-68 seconds / cycle) I was able to mold.
Injection molded product: thick plate 15 cm long x 15 cm wide, 5 mm thick, 40 sheets Furthermore, in order to measure the mechanical strength of the thick plate made of this carbon fiber reinforced pet resin, the resin flow direction along the center of the thick plate ( It cut | judged to MD direction and its orthogonal direction (TD direction), and manufactured the test piece of width 10 mm * length 120 mm (thickness 5 mm). The cuttability of the plate was extremely good, there was no by-product of burrs, and no air, water or oil for cooling was required at all.
The tensile strength was 95/68 MPa, the Young's modulus was 4.2 / 3.6 GPa, the flexural strength was 223/109 MPa, and the flexural modulus was 16.4 / 9.4 GPa in the MD direction / TD direction. Moreover, the average specific gravity of these thick plates was 1.43.
According to the catalog of Toray Industries, Inc., the properties of the raw fiber of the cut fiber of “TORAYCA” are a fiber diameter of 7 μm, a specific gravity of 1.76, a tensile strength of 3,530 MPa, and a tensile elastic modulus of 230 GPa.

  The black plate of thickness 5 mm of the present invention was subjected to thread cutting from the front surface to the back surface using a "tap die set" made in the United States. The 10 mm, 8.5 mm, 7.0 mm, 5.0 mm, 4.2 mm, 3.3 mm and 2.5 mm threadings were extremely smooth with almost no burr by-products and no chip fusion. Since the carbon fiber is as thin as 7 μm in fiber diameter, the machinability is good. Moreover, the consistency with a stainless steel bolt was also good. The injection molded article of the present invention is particularly strong and light, so it is lighter and more corrosion resistant than, for example, high-rise building materials and metals, so it is suitable for applications such as marine materials, coastal road materials and watercraft materials. ing.

According to the present invention, in the production of a carbon fiber reinforced polyester composite, the mechanical strength can be dramatically improved by using a binder and a catalyst in combination. Various physical properties such as corrosion resistance, heat resistance, heat conductivity, conductivity, oil resistance and weather resistance can also be improved. In addition, recovered carbon fibers, regenerated carbon fibers from carbon fiber reinforced epoxy resin composites, and new carbon fibers can also be used.
The present invention is directed to the use of civil engineering and construction materials for the time being. In the near future, applications will be targeted for further weight reduction and energy saving by improving the strength of interior materials and construction materials in advanced industries such as the automobile industry, Shinkansen vehicle industry, aerospace industry, and linear motor cars. Further, since the performances such as radio wave absorbability, conductivity, heat resistance, heat dissipation and the like can be further improved, the availability of the functional material field is large.

Claims (7)

(A) Component 100 parts by weight of polyethylene terephthalate ,
(B) Component 5 to 150 parts by weight of carbon fiber,
0.1 to 2 parts by weight of component (C) multifunctional epoxy compound,
A copolymer composed of 0.01 to 1 part by weight of (D) component-bound reaction catalyst is heated at a temperature above the melting point of the polyethylene terephthalate by reactive extrusion to increase the melt viscosity. And then the step of using the copolymer complex as an injection molded article,
The component (B) carbon fiber has a carboxyl group on the surface,
The component (C) multifunctional epoxy compound contains two or more epoxy groups in the molecule as a binder, and has a weight average molecular weight of 1,000 to 300,000. Method for producing a polyester resin injection molded article. The carbon fiber reinforced polyester resin injection molding according to claim 1, characterized in that the component (A) polyethylene terephthalate contains any one or more kinds of industrial products or recycled products of recovered molded products thereof. How to make the body. The component (B) carbon fiber, consisting of short fiber or powder form fibers consisting of carbon fiber chopped reproduced from short fibers or powdered fibers, aircraft end material consisting recovered carbon fiber chopped in the form of long fibers The method for producing a carbon fiber reinforced polyester resin injection-molded article according to claim 1 or 2 , wherein any one or more kinds of the group is contained. The component (B) carbon fibers, short fibers or powdered fibers consisting of carbon fiber chopped industrial products, consisting of electrochemically oxidized carbon fiber chopped industrial products short fiber or powder form fibers or chemical oxidation The method for producing a carbon fiber reinforced polyester resin injection molded article according to claim 1 or 2, characterized in that it contains any one or more of short fibers or powdered fibers consisting of carbon fiber chops of a treated industrial product. . The method for producing a carbon fiber reinforced polyester resin injection molded article according to any one of claims 1 to 4, wherein the component (C) polyfunctional epoxy compound is used singly or in combination of two or more. The component (D) combined reaction catalyst comprises an alkali metal carboxylate, an alkaline earth metal carboxylate, an alkali metal carbonate or bicarbonate, or an alkaline earth carbonate or bicarbonate. The method for producing a carbon fiber reinforced polyester resin injection-molded article according to any one of claims 1 to 5, comprising any one or more kinds of groups. The component (C) multifunctional epoxy compound and the component (D) combined reaction catalyst are used in the form of a masterbatch based on a resin containing at least one of the group consisting of non-crystalline polyester or polyolefin. The method for producing a carbon fiber reinforced polyester resin injection molded article according to any one of claims 1 to 6, characterized in that