JP2018070855A - Method for producing injection foam molding of carbon fiber reinforced and modified polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber reinforced and modified polyester resin which is excellent in tightness between materials and can achieve high strength of approximately 5-10 times a raw material polyester resin, but specific gravity is heavy as 1.4; and is expected to be reduced further in weight by foaming for expanded applications as an advanced material, including an ocean civil engineering material, a high-rise building material, a railway vehicle material, an automobile material and an aerospace material by making the most use of high corrosion resistance compared to iron and concrete.SOLUTION: A thermoplastic carbon fiber reinforced and modified polyester resin can achieve an increase in strength and reduction in weight by production of a foam sheet and board by using supercritical gas, foamed gas, gas of a chemical foaming agent, microcapsule and the like by an injection molding method and by a core back method.SELECTED DRAWING: None

Description

  The present invention relates to providing a method for producing a foamed molded article of a thermoplastic carbon fiber reinforced / modified polyester resin by an injection molding method.

Thermoplastic polyesters include, for example, polyethylene terephthalate (hereinafter referred to as PET or pet), polybutylene terephthalate (PBT), polycarbonate (PC) and the like as aromatic saturated polyesters. These have excellent physical properties such as transparency, mechanical strength and rigidity as thermoplastic resins, and are widely used as fibers, films, plastics and the like. In particular, in the plastics field, molded products are widely used for bottles, sheets, containers, daily necessities, automobile interior materials, machine parts, electrical / electronic materials, building materials, earth and wood, various industrial products, and the like.
In addition, these polyesters can be used for higher-grade applications due to dramatically improved mechanical strength, heat resistance, and other properties by further mixing glass fibers or carbon fibers into thermoplastic composites. Have been. In particular, since glass fiber is inexpensive, a large amount of GF-PET composite material, GF-PBT composite material, and GF-PC composite material reinforced with this is used. On the other hand, because carbon fiber is high strength but too expensive, these CF-polyester composites have been used only in small amounts for special applications.

In recent years, in the industrial fields such as civil engineering / architecture, high-rise buildings, automobile industry, Shinkansen vehicle industry, linear motor car, aerospace industry, etc., further reduction in weight and energy saving by improving mechanical strength of components In addition, further performance improvements such as corrosion resistance, electrical characteristics, heat resistance, heat dissipation, etc. are required.
Synthetic resins generally have improved moldability and physical properties if their molecular weight is increased. However, inexpensive PET-based polyesters (PET and PBT) are, for example, difficult to obtain a high molecular weight polymer of 50,000 or more due to the production method being a polycondensation method. It is extremely difficult to stably produce an extrusion-molded product by the horizontal extrusion method, particularly an extrusion foam-molded product and a high-strength injection foam-molded product. In addition, the solid layer polymerization method for increasing the molecular weight of this inexpensive PET-based polyester to about twice the molecular weight requires several hours, so that the productivity is low. In addition, there was a weak point that required large-scale production facilities for petrochemical complexes.

As shown in Patent Document 1, Patent Document 2 and Patent Document 3, the present inventors adopt a reactive extrusion method for the medium molecular weight body having a carboxyl group at the terminal with these inexpensive PET-based polyesters, and epoxy resin Depending on the system binder (also called chain extender, thickener) and catalyst, polyester can be reacted with each other to achieve high productivity in high molecular weight in a few minutes or less, using compact and inexpensive equipment A production method by reactive extrusion was provided. However, while there has been a breakthrough in molding processability due to an increase in the melt tension of polyester, on the other hand, there was hardly any effect expected at the beginning for improvement in mechanical properties.
In addition, as shown in Patent Document 4 and Patent Document 5, the present inventor made an inexpensive new carbon fiber made of polyethylene terephthalate (PET) or a high-count PAN-based rayon as a raw material, 6 mm long (ZOLTEK). (Made by company) ・ Uses 15 and 30% by weight of 6 mm length, and reacts with a twin-screw extruder in the presence of an epoxy resin binder (chain extender) and catalyst to reinforce carbon fiber. The modified patting resins have greatly improved mechanical strength from about 2.9 times to about 3.5 times in tensile strength and from about 5.7 times to about 10 times in flexural modulus. In addition, in the patent document 6, the present inventor succeeded in producing a flat plate and an extruded foam plate by a T-die extrusion method using a ZOLTEK carbon fiber reinforced / modified pet resin in the same manner.

Notice No. 3503952 International Publication WO2009 / 004745 A1 US 8258239B2 registration JP-A-2015-007215 JP-A-2006-157939 WO2016 / 117786

  Further weight reduction by improving mechanical strength of structural materials in advanced industrial fields such as civil engineering / architecture, high-rise buildings, small flying bodies (drones), automobile industry, Shinkansen vehicle industry, linear motor car, aerospace industry, etc.・ In addition to energy saving, further improvements in performance such as corrosion resistance, electrical conductivity, heat resistance and heat dissipation are required. In particular, an object of the present invention is to produce an industrial flying object (drone) device, a camera, a container for storing a battery, an automobile engine cover, and the like at high speed by injection foam molding. In addition, it aims to develop applications such as light weight materials for high-rise buildings, high strength / corrosion resistant materials for coastal expressways, corrosion resistant / high strength materials for marine structures, and corrosion resistant materials for surface flying boats.

Means to try to solve the problem

  An object of the present invention is to provide a light-weight new foam molded article by injection-foaming a carbon fiber reinforced / modified PET resin having improved strength at a high speed. That is, the present invention produces an injection-foamed molded article of carbon fiber-reinforced / modified polyester resin characterized by adding a foaming agent to carbon fiber-reinforced / modified PET polyester resin and foaming by an injection molding method. A method is provided.

More specifically, the present invention provides the following production method.
The present invention is an injection molding method in which a foaming agent is first added to a carbon fiber reinforced / modified polyester resin having a melt flow rate of 1 to 40 g / 10 min according to JIS method K7210 (260 ° C., load 2.16 Kg). The present invention provides a method for producing an injection-foamed molded article of a carbon fiber reinforced / modified polyester resin characterized by being foamed by the above method.

  The present invention secondly provides a method for producing an injection foam molded article of carbon fiber reinforced / modified polyester resin, wherein the injection molding method is a core back type.

  Thirdly, the foaming agent of the carbon fiber reinforced / modified polyester resin is characterized in that the foaming agent is a volatile foaming agent and is a supercritical fluid inert gas nitrogen gas or carbon dioxide gas. The manufacturing method of this is provided.

Fourthly, the present invention provides a method for producing a foamed article of carbon fiber reinforced / modified polyester resin, wherein the foaming agent is a volatile foaming agent and is an inert gas such as carbon dioxide and / or nitrogen gas. Is to provide.

Fifthly, the present invention provides a method for producing a foamed article of carbon fiber reinforced / modified polyester resin, wherein the foaming agent is a heat decomposable foaming agent.

  The present invention sixthly provides a method for producing a foamed molded article of carbon fiber reinforced / modified polyester resin, wherein the foaming agent is a microcapsule containing a hydrocarbon compound having a low boiling point. is there.

Effect of the invention

Although the present inventors succeeded in the manufacture of the foam board by the extrusion method to a horizontal direction by patent document 6. However, for example, in order to produce a specific shaped body such as an industrial flying object (drone) device, a camera, a battery storage container, an automobile engine cover, etc., the foam plate is again heat-molded into a specific shape. It must be cut.
According to the present invention, if a male and female mold of an injection foam molded body having a specific shape is used, a container for storing a drone device, a camera, a battery, and an engine cover having a complicated shape can be produced at high speed.
In the present invention, there are chopped products such as inexpensive new carbon fiber by large tow method, recovered carbon fiber from less-priced bobbin from the cheaper aircraft industry, and recycled carbon fiber from carbon fiber reinforced composite material (CFRP) of aircraft end material. It can be suitably used as a raw material. Therefore, it is possible to greatly reduce the cost of the injection foam molded article.

Hereinafter, the present invention will be described in detail.
The carbon fiber reinforced / modified polyester resin used in the present invention has a melt flow rate of 1 to 40 g / 10 min according to JIS method K7210 (260 ° C., load 2.16 Kg), and 100 weights of component (A) polyester. Parts, (B) component carbon fiber 5-150 parts by weight, (C) component multifunctional epoxy compound containing two or more epoxy groups in the molecule 0.1-2 parts by weight, (D ) A composition composed of 0.01 to 1 part by weight of a component binding reaction catalyst is heated at a temperature equal to or higher than the melting point of the polyester.
[Polyester of component (A)]
The polyester of component (A) as the main raw material in the present invention is an aromatic saturated polyester. Specific examples of this series of polyesters include polyethylene terephthalate (PET), low melting point PET copolymerized with a small amount of isophthalic acid, a copolymer of ethylene glycol, cyclohexanedimethanol and terephthalic acid (PETG), polytetramethylene terephthalate (poly Butylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), and the like. Polybutylene terephthalate (PBT) is preferred. Mass-produced and extremely inexpensive polyethylene terephthalate (PE

[Carbon fiber of component (B)]
The carbon fiber of the component (B) in the present invention preferably has an oxygen-containing functional group, particularly a carboxyl group on its surface. As the carbon fiber, it is preferable to use a PAN-based industrial product as the first series. For example, an inexpensive carbon fiber chop manufactured by ZOLTEK (USA) (a rattan (LT) PAN-based carbon fiber “Panex 35” 6 mm long manufactured by ZOLTEK, USA) is particularly preferable. Toray Industries' high-performance carbon fiber "Torayca" T500, T600, T700 series for aircraft can also be used. In addition, industrial use cut fiber T008 series, T010 series, TS12-006 (cut length 3-12 mm), or “Torayca” milled fiber MLD series (fiber length 30-150 μm) can also be used as a raw material. In general, these carbon fiber industrial products have a relatively high carboxyl group content.
Pitch-based carbon fiber industrial products of Kureha Co., Ltd. and Osaka Gas Chemical Co., Ltd. can be used as the second series. These have a relatively large functional group content, but have a slightly lower strength. Since the strength of the molded product has an isotropic advantage, it can be preferably used.

As the carbon fiber of the component (B) of the present invention, regenerated carbon fiber recovered from a carbon fiber reinforced thermosetting epoxy resin composite (CFRP) can be preferably used as the third series. Carbon fiber reinforced thermosetting epoxy resin composite (CFRP), which is the raw material, is currently milled by about 40% when milling aircraft, drill chips by-produced during boring, fishing rods, golf Obtained from tees, etc. The future is expected to be derived in large quantities from CFRP scrap, which accounts for about 65% of large aircraft bodies.
In addition, bobbin-wrapped long-fiber cut fibers (cut length: 3-12 mm) collected as semi-finished products at the time of manufacturing aircraft bodies and the like can be used satisfactorily because they are of good quality and extremely inexpensive.
Recycled carbon fiber introduces a large number of carboxyl groups by performing electrolytic oxidation treatment under the control of reaction conditions according to the Sugiyama teaching method of Hachinohe and National College of Technology as illustrated in Production Example 1 of the Example. The product obtained can be used particularly preferably. The amount of carboxyl groups in the regenerated carbon fiber of the present invention usually contains a range of 0.01-0.20 mmol / g. The range that can be preferably used is 0.02-0.15 mmol / g.
The fiber length of the regenerated carbon fiber depends on the size of the CFRP end material of an aircraft or the like and the size of chips by 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 (3-100 mm) or powdered fiber (3 mm or less). Either can be preferably used in the present invention.

[Binder for component (C)]
The binder of the component (C) of the present invention preferably has a weight average molecular weight of 1,000 to 300,000, and 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. A product in which a glycidyl group containing an epoxy ring is suspended in a resin that forms a high molecular weight skeleton in a pendant form, or a product containing an epoxy group in the molecule, such as NOF's "Murproof" series, BASF Japan Co., Ltd.'s “John Krill ADR” series can be used.

[(D) Component Binding Reaction Catalyst]
The coupling reaction catalyst as the component (D) in the present invention includes (1) alkali metal organic acid salts, carbonates and hydrogen carbonates, and (2) alkaline earth metal organic acid salts, carbonates and hydrogen carbonates. A catalyst containing at least one selected from the group consisting of: As the organic acid salt, carboxylate, acetate and the like can be used, but stearates are particularly preferable among the carboxylates. The metal that forms the metal salt of the carboxylic acid can be an alkali metal such as lithium, sodium and potassium; an alkaline earth metal such as magnesium, calcium, strontium and barium.

  In the present invention, a spreading agent can be used effectively, but it is particularly effective when the polyester (A) and the carbon fiber (B) are powders. Usually, paraffin oil, liquid paraffin, trimethylsilane or the like can be used. Liquid paraffin is particularly preferred because it is nonpolar, has a high boiling point and is a moderately viscous fluid. The addition amount is 0.01-1 part by weight with respect to the component (A). These spreading agents are necessary for uniformly adhering the (B) component carbon fibers to the (A) polyester pellets or powder, and the carbon fibers / powder soars into the atmosphere. It is an indispensable auxiliary agent necessary to prevent adverse effects on electrical instrumentation equipment.

As the foaming agent of the present invention, conventionally known foaming agents can be used. For example, an inert gas such as carbon dioxide and / or nitrogen gas can be used as the volatile foaming agent. These do not cause fires and do not require explosion-proof equipment, so they can be operated in small and medium-sized town factories. Suitable for industrial production of the foam of the present invention having a low expansion ratio. In particular, in the injection foam molding of the present invention, it is effective to use a supercritical fluid of nitrogen gas and / or carbon dioxide gas to make the bubbles finer and make the molded body uniform. Further, the supercritical nitrogen gas improves the dimensional accuracy of the molded body as compared with the supercritical carbon dioxide gas.
As the foaming agent of the present invention, a heat decomposable foaming agent can be used. Since the melting point of the polyester resin exceeds 200 ° C., there are few chemical substances that can actually be used. A baking soda-based blowing agent used for low foaming of polypropylene can be used. However, since it is accompanied by the generation of water vapor, short-term equipment maintenance is required for foam molding of polyester resin which is easily hydrolyzed.
It is difficult to use low-boiling hydrocarbon compounds such as Flopan, butane, and hexane as they are. They are used in microencapsulation or in the form of a polyolefin-based masterbatch.

Next, the present invention will be described in detail based on examples. The evaluation methods for the polyester and the polyester / carbon fiber composite of the present invention are as follows.
(1) Measuring method of intrinsic viscosity (IV value) of PET, etc. Using a mixed solvent of equal weight of 1,1,2,2-tetrachloroethane and phenol, it was measured at 25 ° C. with a Canon Fuenske viscometer. Or, the manufacturer's catalog value was adopted.
(2) Measurement method of melt flow rate (MFR) According to the condition 20 of JIS K7210 (ISO 1133 ASTM D1238), it measured on condition of temperature 280 degreeC or temperature 260 degreeC and load 2.16kg. However, the resin used was 120 ° C. × 12 hours or 140 ° C. × 4 hours in advance and dried with hot air or vacuum.
(3) Measuring method of specific gravity It measured also by the dimension measuring method of JISK7222. Alternatively, according to JIS K7112, Method A (in-water replacement method), alcohol was measured as a liquid for resin pellets or small pieces of molded articles.
(4) Measuring method of mechanical strength 10 mm width was cut out from the injection foam molded plate.
(According to ISO 20753, JIS K7139 multipurpose specimen type A1 type: total length 120 mm, thickness 4 mm, chuck portion width 20 mm, constriction portion width 10 mm)
Shape of test piece: Bending test piece Strip type 80mm length x 10mm width (thickness 4mm)
Tensile specimens Strip type 100mm length x 10mm width (thickness 4mm)
Bending test: The flexural modulus is calculated from linear regression of 0.05% and 0.25% of the strain interval (JIS K771). Evaluation was made with an average value of 3-5 points.
The bending strength was evaluated by an average value of 3-5 points, with 3 point bending performed at a test speed of 5 mm / min.
Tensile test: The tensile strength was measured at a test speed of 2 mm / min, and 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 and others).

  The manufacture example about the basic resin material concerning this invention is shown.

Production Example 1

[Production of ZOLTEK Carbon Fiber Reinforced / Modified Pet Resin Pellets R1 Consisting of 15% Pet Resin, Carbon Fiber Chop, and Modifier]
General-purpose PET resin pellets (bottle grade: Taiwan / South Asia 3802T, IV value 0.80) as A component polyester, and polyfunctional epoxy resin as binder for C component 0.60 part by weight, 0.16 part by weight of the mixed catalyst for the D component binding reaction and 0.06 part by weight of liquid paraffin as a spreading agent for the E component were uniformly mixed by a super mixer. These were delivered to the first hopper for main resin extrusion. On the other hand, LT carbon fiber chops (PAN-based carbon fiber “Panex 35” 6 mm long from rattan (LT) rayon of ZOLTEK, USA) as a B component carbon fiber were delivered to the second hopper for the side feeder.
Using the same direction twin screw extruder (60 mm diameter, 1 vent type) manufactured by Toshiba Machine Co., Ltd., the set temperature of the cylinder and die consisting of 10 blocks of this extruder is 150-270 ° C. and the screw rotation speed is 150 rpm. did. Using a gravimetric weighing feeder, a mixed resin such as A component, C component, and D component is reactively extruded from the first hopper at a rate of 100 kg / h, and a carbon fiber chop is fed from the second hopper to 17.6 kg / h. Side feed was continuously performed at a rate of (carbon fiber content: 15%).
The strand was continuously extruded into water from a diagonally downward nozzle having a diameter of 3 mm and cut with a rotary cutter to produce about 180 kg of black resin pellet R1. The strand from the mold outlet to the basin was linear and the melt tension increased. The shape was cylindrical and the diameter was about 3.4 mm × length was about 6 mm. Moreover, MFR (260 degreeC, load 2.16Kg) was 6.2g / 10min.
This carbon fiber reinforced / modified pet resin black pellet R1 is dried with hot air overnight at 120 ° C., and a hybrid injection molding machine FNZ60 manufactured by Nissei Plastic Industry Co., Ltd. (clamping pressure 140 tons, screw diameter 60 mm) is used. The following injection molded article was molded under the conditions of a molding temperature of 280 ° C., a mold temperature of 130 to 145 ° C., an injection pressure of 53 MPa, an injection speed of 12 mm / s, a screw rotation speed of 80 rpm, and a cooling time of 20 seconds.
Shape of multi-purpose test piece: ISO 20553, JIS K7139 A1 type, total length 120 mm, thickness 4 mm, chuck portion width 20 mm, constriction portion width 10 mm,
Same length 80mm (Z runner method)
The ZOLTEK carbon fiber (CF15%) reinforced / modified pet resin pellet R1 showed no injection by-product and showed good injection moldability. The surface of the test piece was smooth and glossy. The test was performed at a tensile speed of 2 mm / min and a bending speed of 5 mm / min. The physical property values of the pellets are shown in Table 1.
Compared to the sticky resin-only transparent pellet P1 of Production Example 8, the mixing effect of ZOLTEK carbon fiber of about 15% in this Example R1 is 2.9 times the tensile strength, 4.1 times the Young's modulus, and the bending strength. It is 3.5 times and the flexural modulus is 5.7 times.

Production Example 2

[Manufacture of ZOLTEK Carbon Fiber Reinforced / Modified Pet Resin Pellets R2 Composed of 30% Pet Resin, Carbon Fiber Chop, and Modifier]
Pellets R2 were manufactured under substantially the same conditions as in Production Example 1 described above. However, the side feed speed was doubled to reduce the carbon fiber chop content to about 30%. General-purpose PET resin pellets (bottle grade: Taiwan / South Asia 3802T, IV value 0.80) as A component polyester, and polyfunctional epoxy resin as binder for C component 0.56 parts by weight, 0.16 parts by weight of the mixed catalyst for the D component binding reaction and 0.06 parts by weight of liquid paraffin as the E component spreading agent were uniformly mixed by a super mixer. These were delivered to the first hopper for main resin extrusion. Meanwhile, an LT carbon fiber chop (a rattan PAN-based carbon fiber “Panex 35”, 6 mm long from ZOLTEK, USA) as a B-component carbon fiber was delivered to a second hopper for a side feeder.
A twin-screw extruder in the same direction (caliber 60 mm, 1 vent type) was used, and the set temperature of the cylinder and the die consisting of 10 blocks of this extruder was 150 to 270 ° C. and the screw rotation speed was 150 rpm. Using a gravimetric weighing feeder, a mixed resin such as A component, C component, and D component is reactively extruded from the first hopper at a rate of 100 Kg / h, and a carbon fiber chop from the second hopper is 42 Kg / h (carbon Side feed was continuously performed at a rate of 30% fiber content).
The strand was continuously extruded into water from an obliquely downward nozzle having a diameter of 3 mm, and cut with a rotary cutter to produce about 250 kg of black resin pellet R2. The strand from the mold outlet to the basin was linear and the melt tension increased.
The shape was cylindrical and the diameter was about 3.4 mm × length was about 6 mm. Moreover, MFR (260 degreeC, load 2.16Kg) was 6.7 g / 10min. This carbon fiber (CF 15%) reinforced / modified pet resin pellet R2 showed no injection by-product and showed good injection moldability, and the surface of the test piece was almost smooth and glossy. The physical property values of the pellets are shown in Table 1. Compared with the transparent pellet P1 made only of the PET resin of Production Example 8, the mixing effect of ZOLTEK carbon fiber of about 30% of this Example R2 is 3.5 times the tensile strength, 6.1 times the Young's modulus, and 3 times the bending strength. It was 9 times and the flexural modulus was 10.3 times. Carbon fiber reinforced / modified PET resin pellets with good injection moldability and improved mechanical strength were obtained.

Production Example 3

[Manufacture of pellets P1 using only pet resin]
Using only 100 parts by weight (3 kg) of A component PET resin (commercially available pellets for PET bottles: IV value 0.80, MFR 35 g / 10 min, 280 ° C., 2.16 kg), Production Examples 4 and 5 Repellet P1 was produced under substantially the same extrusion conditions to obtain 2.9 kg of transparent pellets. The strand drooped in an arc from the mold outlet to the water surface, meandering in the basin, indicating a low melt tension. The transparent pellet P1 was cylindrical and had a diameter of about 3 mm and a length of about 5 mm. Moreover, MFR (280 degreeC, load 2.16Kg) was 57 g / 10min, and was comparatively low melt viscosity.
This PET resin-only pellet P1 was injection-molded to form tensile test pieces and bending test pieces in the same manner as in Production Examples 1 and 2. The tensile strength was 59 MPa, the Young's modulus was 1.9 GPa, the bending strength was 84 MPa, and the flexural modulus was 2.1 GPa.

Example 1-3

[Manufacture of injection flat plate A and injection foamed plate B1-B2 with supercritical nitrogen gas from ZOLTEK (30%) carbon fiber reinforced / modified PET resin pellet R2]
A flat plate mold (inner dimensions 360 mm × 250 mm, thickness 4 mm, volume 360 cc) was installed in a microcell foam (MuCell) injection molding apparatus (450 tons) of Nippon Steel Corporation.
(Example 1) Carbon fiber reinforced pet resin R2 containing ZOLTEK carbon fiber (6 mm chop, 30%) (dried black pellet, specific gravity 1.45, MFR 6.7 g / 10 min: 260 ° C., load 2.16 Kg) 100 Injection molding was carried out at a cylinder temperature of 260-290 ° C., a mold temperature of 140-150 ° C., and a plate thickness of 4.0 mm. The produced flat plate A (36 cm × 25 cm, thickness 4 mm) had an average weight of 532 g, a specific gravity of 1.48 and no foam. The bending elastic modulus of the test piece cut out in the flow direction (MD) of the carbon fiber from the resin injection portion was 14.6 GPa.
Example 2 An injection foam (MuCell) having a resin filling rate of 80% was manufactured by injecting a predetermined amount of supercritical nitrogen gas under the same conditions. The average weight of the foamed flat plate B1 (36 cm × 25 cm, thickness 4 mm) was 432 g, the specific gravity was 1.19, and the foaming ratio was 1.24. The bending elastic modulus of the cut specimen in the flow direction (MD) of the carbon fiber from the resin injection portion was 11.5 GPa.
Example 3 Under the same conditions, a predetermined amount of supercritical nitrogen gas was injected to produce an injection foam (MuCell) with a resin filling rate of 70%. The average weight of the foamed flat plate B2 (36 cm × 25 cm, thickness 4 mm) was 370 g, the specific gravity was 1.03, and the foaming ratio was 1.44. The bending elastic modulus of the cut specimen of the carbon fiber flow direction (MD) from the injection part of the tree finger was 10.1 GPa.

Example 4-5

[Manufacture of injection flat plate C1 and injection foamed plate C2 by core back type from ZOLTEK (30%) carbon fiber reinforced / modified PET resin pellet R2 using supercritical nitrogen gas]
(Example 4) The same apparatus as in Example 1 was used. The plate thickness was set to 2.7 mm when the core back type injection foamed plate was not foamed to produce a flat plate. The produced flat plate C1 (36 cm × 25 cm, thickness 2.7 mm) had an average weight of 342 g, a specific gravity of 1.41, and no foam.
(Example 5) The same apparatus as in Example 4 was used. An injection foamed board was manufactured by setting the thickness of the core back type injection foamed board to 4.0 mm. The produced foamed flat plate C2 (36 cm × 25 cm, thickness 4.0 mm) had an average weight of 349 g, a specific gravity of 0.969, and a volume foaming ratio of 1.48. The bending elastic modulus of the test piece cut out in the flow direction (MD) of the carbon fiber from the resin injection portion was 9.20 GPa.

Example 6-13

[Manufacture of injection foamed plates D1-D8 by core back type using supercritical nitrogen gas from ZOLTEK (30%) carbon fiber reinforced / modified PET resin pellet R2]
The core back type continued.
(Example 6) The plate thickness was 2.7 → 5.26 mm (D1): The foam plate weight was 348 g, the specific gravity was 0.421, and the volume foaming ratio was 1.95.
(Example 7) The plate thickness was 2.7 → 6.20 mm (D2): The foam plate weight was 349 g, the specific gravity was 0.422, and the volume foaming ratio was 2.30.
(Example 8) The plate thickness was 2.7 → 7.16 mm (D3): The foam plate weight was 347 g, the specific gravity was 0.363, and the volume foaming ratio was 2.65.
(Example 9) Thickness of the plate was changed from 2.7 to 8.10 mm (D4): The foam plate weight was 348 g, the specific gravity was 0.322, and the volume foaming ratio was 3.00.
(Example 10) The plate thickness was 2.7 to 9.10 mm (D5): The foam plate weight was 346 g, the specific gravity was 0.285, and the volume foaming ratio was 3.37.
(Example 11) The plate thickness was 2.7 → 10.1 mm (D6): The foam plate weight was 348 g, the specific gravity was 0.258, and the volume foaming ratio was 3.74.
(Example 12) The plate thickness was 2.7 → 11.0 mm (D7): the foam plate weight was 348 g, the specific gravity was 0.237, and the volume foaming ratio was 4.07.
(Example 13) The plate thickness was 2.7 → 12.7 mm (D8): the foam plate weight was 346 g, the specific gravity was 0.204, and the volume foaming ratio was 4.70.
In a series of core back type injection foaming tests, (Example 9) Thickness from 2.7 to 8.10 mm (D4) product foaming ratio up to 3.37, foam molding is stable and air bubbles are uniformly dispersed and good Met. The product of the present invention was surprisingly good in molding stability and excellent in surface smoothness as compared with existing nylon-glass fiber systems.

Examples 14-17

[Manufacture of ZOLTEK (30%) carbon fiber reinforced / modified PET resin pellets R2 with core back injection plate E1, foams E2 and E3 with chemical foaming agent, and injection foam E4 with microcapsules]
A flat plate mold (inner dimensions: 100 mm × 200 mm) was installed in an injection molding apparatus (MD100X, 100 tons) of Niigata Machine Techno.
(Example 14) Carbon fiber reinforced pet resin R2 containing ZOLTEK carbon fiber (6 mm chop, 30%) (dried black pellet, specific gravity 1.45, MFR 6.7 g / 10 min: 260 ° C., load 2.16 Kg) 100 Injection molding was carried out at a cylinder temperature of 260-300 ° C., a mold temperature of 70-80 ° C., and a plate thickness of 2.4 mm. The average weight of the manufactured flat plate E1 (thickness: 2.4 mm) was 78.3 g, the specific gravity was 1.46, and no foam was generated. Good releasability from the mold and good surface smoothness.
(Example 15) Under the same conditions, 3 parts by weight of a chemical foaming agent (manufactured by Eiwa Kasei Kogyo Co., Ltd., Polyslen E16D, decomposition temperature 200 ° C., gas generation amount 190 ml / 5 g) was mixed to obtain a core back thickness of 2.4. → An injection foam board was manufactured at 3.6 mm. The foamed flat plate E2 had an average weight of 76.2 g and a volume foaming ratio of 1.5. Good releasability from the mold and good surface smoothness.
(Example 16) Under the same conditions, the chemical foaming agent (manufactured by Eiwa Kasei Kogyo Co., Ltd., Polyslen EE204, decomposition temperature 240 ° C., gas generation amount 80 ml / 5 g) was changed to 5 parts by weight, and the core back thickness 2. An injection foam board was manufactured at 4 → 3.6 mm. The foamed flat plate E3 had an average weight of 75.8 g and a volume foaming ratio of 1.5. Good releasability from the mold and good surface smoothness.
(Example 17) Under the same conditions, 3 parts by weight of a microcapsule (Matsumoto Yushi Seiyaku, MBF2860PE, decomposition temperature 280 ° C., gas generation amount 190 ml / 5 g) was mixed to obtain a core back thickness of 2.4. → An injection foam board was manufactured at 3.6 mm. The foamed flat plate E4 had an average weight of 77.1 g and a volume foaming ratio of 1.5.

According to the present invention, an injection foam of carbon fiber (30%) reinforced / modified PET resin having a flexural modulus exceeding 20 GPa, which is the world's highest grade, is produced by supercritical flow gas, chemical foaming agent and microcapsule type foaming agent. And 1.2-3 times (specific gravity 1.2-0.48) could be easily manufactured by the supercritical flow gas foaming method and the core back method.
By reinforcing the carbon fiber, the PET-based polyester resin has been able to dramatically increase the mechanical strength, but this time the weight has been reduced by foaming. INDUSTRIAL APPLICABILITY The present invention has been rapidly developed for the time being, and is necessary for high-strength and light-weight industrial flying vehicles “drones” such as instruments, cameras, containers for batteries, and automobiles that require high-strength, light weight, heat resistance, and heat dissipation. The target engine cover. In addition, various physical properties such as corrosion resistance, heat resistance, heat transfer, conductivity, oil resistance, and weather resistance can be improved. Further, the cost can be reduced by using recovered carbon fibers, recycled carbon fibers from carbon fiber reinforced epoxy resin composites, and inexpensive new carbon fiber strength.
In the future, it will be used for civil engineering and building materials. In the near future, we will target applications for further weight and energy savings by improving the strength of interior materials and components in advanced industries such as the railway vehicle, automobile industry, Shinkansen vehicle industry, linear motor car and aerospace industry. To do. Moreover, since further performance improvements such as radio wave absorption, conductivity, heat resistance, and heat dissipation can be achieved, the applicability in this functional material field is great.

Claims (6)

  A foaming agent is added to a carbon fiber reinforced / modified polyester resin having a melt flow rate of 1-40 g / 10 min according to JIS method K7210 (260 ° C., load 2.16 kg), and foamed by an injection molding method. A method for producing an injection-foamed molded article of carbon fiber reinforced / modified polyester resin.   2. The method for producing an injection-foamed molded article of carbon fiber reinforced / modified polyester resin according to claim 1, wherein the injection molding method is a core back type.   2. The foamed molded article of carbon fiber reinforced / modified polyester resin according to claim 1, wherein the foaming agent is a volatile foaming agent and is nitrogen gas and / or carbon dioxide gas as a supercritical fluid inert gas. Production method.   The method for producing a foamed article of carbon fiber reinforced / modified polyester resin according to claim 1, wherein the foaming agent is a volatile foaming agent and is an inert gas such as carbon dioxide gas or nitrogen gas.   The method for producing a foamed article of carbon fiber reinforced / modified polyester resin according to claim 1, wherein the foaming agent is a heat decomposable foaming agent.   The method for producing a foamed article of carbon fiber reinforced / modified polyester resin according to claim 1, wherein the foaming agent is a microcapsule containing a hydrocarbon compound having a low boiling point.