JP4443148B2 - Carbon fiber bundle, chopped carbon fiber bundle and method for producing the same, carbon fiber reinforced thermoplastic resin composition and molded article thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbon fiber bundle used as a reinforcing material for a thermoplastic resin, a chopped carbon fiber bundle and a method for producing the same, a fiber reinforced thermoplastic resin composition using the chopped carbon fiber bundle, and a molded article comprising the same. Specifically, the present invention relates to a sizing agent suitable for producing a carbon fiber bundle.
[0002]
[Prior art]
Carbon fiber is known as a reinforcing material in a fiber reinforced resin, and a composite material containing the carbon fiber is called a fiber reinforced composite material. In general, carbon fibers are bundled and subjected to a sizing treatment to attach a sizing agent mainly composed of a water-soluble or water-dispersible epoxy resin for the purpose of improving the handleability and the physical properties of the composite material. Has been. On the other hand, in a fiber reinforced composite material using a thermoplastic resin as a matrix resin, the carbon fiber bundle is usually provided in the form of a chopped carbon fiber bundle cut to a length of 5 to 15 mm, but in the form of a chopped carbon fiber bundle. In some cases, 2-5 mass% of a sizing agent that is compatible with the matrix resin is applied in order to impart convergence.
[0003]
In producing pellets by kneading a chopped carbon fiber bundle and a thermoplastic resin, it is necessary to quantitatively provide the chopped carbon fiber bundle in an extruder. For this purpose, the morphological stability of the chopped carbon fiber bundle is required. Sex is important. If the form is not appropriate, ejection spots occur, causing carbon fiber content spots. Further, since a constant extrusion speed cannot be obtained, strand breakage may occur, and the productivity of pellets may be significantly reduced. Furthermore, a material in which a thermoplastic resin of a type called a long fiber pellet is used as a matrix resin is also attracting attention. In this case, a carbon fiber bundle is put into a pellet manufacturing process in the form of a continuous bundle without being chopped. It will be. In this case, it is indispensable to attach a sizing agent to the carbon fiber bundle because fluff and fly are easily generated in the carbon fiber bundle, are easily broken, and are difficult to handle.
[0004]
On the other hand, polycarbonate resin, nylon resin, polyester resin, and the like are often used as the thermoplastic resin of the matrix resin. Recently, however, polyolefin resins are increasingly used from the viewpoint of recyclability and economy. In particular, polypropylene resin is a matrix resin that has attracted attention in recent years.
[0005]
Since the polyolefin-based resin is basically nonpolar, the interfacial adhesiveness with a reinforcing fiber such as carbon fiber or glass fiber is very poor, and the mechanical properties as a composite material are often not sufficiently exhibited. Therefore, a small amount of acid-modified polyolefin resin is added to the matrix resin to improve adhesion, or glass fiber treated with a sizing agent composed of an olefin resin and a silane coupling agent, and further, modified polypropylene is an essential component. The prescription which raises the interfacial adhesiveness with the polypropylene which is a matrix, and polyolefin resin by processing inorganic fiber, such as glass fiber, with the sizing agent which is made (refer patent document 1).
[0006]
Further, as the performance and characteristics of carbon fibers as a reinforcing material are widely recognized, carbon fibers that can be mass-produced and that are inexpensive and excellent in economic efficiency have been demanded. In particular, one of the major factors in using a polyolefin resin as a matrix resin is its low cost. Therefore, there is an extremely strong demand for lower prices for carbon fibers, and in order to realize lower prices, it is necessary to improve the production capacity per equipment or per hour. The thickening has been proposed (see Patent Document 2).
[0007]
However, the method of adding the modified polyolefin to the matrix resin requires a large amount of addition in order to improve the interfacial adhesion with the fiber as a sufficient reinforcing material, and it does not become excellent in recyclability and economy. . Therefore, a technique is excellent in which such a compound is unevenly distributed in the interfacial phase when such a binder is adhered to the surface of the fiber and combined. On the other hand, since carbon fiber does not have many hydroxyl groups like the glass fiber surface, the silane coupling agent has a considerably low efficiency of improving the interfacial adhesion and is expected to act as a central coupling agent. It is not possible. Furthermore, the filament diameter as a single fiber is 7 μm or less, which is very thin as compared with 10 to 16 μm of glass fiber. Further, the number of filaments forming the carbon fiber bundle is 12,000 or more, which is remarkably larger than that of a general glass fiber bundle of about 600. Therefore, even if the sizing agent for glass fibers is used as it is, the bundle property, draping property, and handleability of the fiber bundle are not at a sufficient level, and the interfacial adhesion after the composite is not improved as expected. It has become.
[0008]
Moreover, in the sizing agent which uses the modified polypropylene described in Patent Document 1 as an essential component, it is not yet at a level that sufficiently exhibits interfacial adhesion with an olefin resin, and is sufficient for a carbon fiber bundle. Convergence, drape, and handleability could not be imparted. Furthermore, when trying to apply thickening to the carbon fiber bundle, there are the following disadvantages.
[0009]
Although we mentioned that morphological stability is important for chopped carbon fiber bundles, the bulkiness of unit bundles increased with increasing weight, and it was in line with fiber orientation due to uneven sizing agent adhesion and bundle width expansion. There is a problem that cracking is likely to occur and it is difficult to obtain a chopped carbon fiber bundle having a uniform bundle width. Further, when the processing speed (conveying speed) in the cutting process is increased, there is a problem that as the weight becomes thicker, fluffing and winding occur frequently in the guide, the bar, etc., and the productivity is lowered. In addition, due to the occurrence of fluff, there is a possibility that the process passability at the time of compounding is deteriorated.
[0010]
[Patent Document 1]
JP-A-6-107442
[Patent Document 2]
JP 2000-248432 A
[Patent Document 3]
[0011]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a carbon fiber bundle treated with a sizing agent that forms good interfacial adhesion with a polyolefin resin, particularly a polypropylene resin, as a matrix resin. A chopped carbon fiber bundle having excellent shape stability, excellent handleability during the production of a fiber reinforced composite material, and excellent economic efficiency, and a carbon fiber reinforced thermoplastic resin composition and its composition It is to provide a molded article comprising:
[0012]
[Means for Solving the Problems]
The carbon fiber bundle of the present invention has an acid-modified polypropylene resin (compound a) having a number average molecular weight of 20,000 or less and an acid value measured according to ASTM D1386 of 23 to 120 mgKOH / g, a fat that is not polyoxy It is characterized by being converged with a sizing agent comprising a resin (compound b) having an epoxy group main chain and containing an epoxy group, and an olefinic thermoplastic elastomer resin (compound c) as constituent components.
[0013]
The acid-modified polypropylene resin, which is one of the constituent components of the sizing agent, is an essential component when the carbon fiber and the matrix resin are combined. When complexing, the acid group in the acid-modified polypropylene resin molecule enhances the interaction with the carbon fiber surface, while the polypropylene chain that is the skeleton is entangled with the polymer molecule if it is a matrix resin such as polyolefin. As a result, the acid-modified polypropylene resin acts as an effective coupling agent. The molecular weight of the acid-modified polypropylene resin is desirably 20000 or less, preferably 10,000 or less, and more preferably 7000 or less. When the molecular weight exceeds 20000, the mobility of the acid-modified polypropylene resin in the vicinity of the interfacial phase is insufficient, the degree of entanglement between the molecules with the matrix resin is small, and the interfacial adhesion cannot be sufficiently increased. Here, the number average molecular weight of the acid-modified polypropylene resin is measured by GPC.
[0014]
The acid value measured according to ASTM D1386 is preferably 23 to 120 mgKOH / g, preferably 29 to 90 mgKOH / g, more preferably 35 to 80 mgKOH / g. When the acid value is less than 23 mgKOH / g, the interaction with the carbon fiber surface is small and high interfacial adhesion cannot be obtained. On the other hand, when the acid value exceeds 120 mgKOH / g, the matrix resin, particularly the polyolefin resin, As a result, the entanglement with the matrix polymer molecules does not occur sufficiently, and the interfacial adhesion cannot be sufficiently increased. Specific examples of such acid-modified polypropylene resins include GF-101 (aqueous emulsion) manufactured by Yoshimura Oil Chemical Co., Ltd., Hostamont AR503, AR504 manufactured by Clariant, and the like.
[0015]
The resin (compound b) which has an aliphatic main chain which is not a polyoxy type and is an epoxy group, which is a constituent component of the sizing agent, can exhibit more excellent interfacial adhesion with the matrix resin. It is known that the epoxy group has a very strong chemical interaction with the carbon fiber surface and forms a chemical bond relatively easily. Therefore, by making it coexist with acid-modified polypropylene resin, it becomes possible to act as a more effective matrix resin and carbon fiber coupling agent. Any epoxy group-containing resin can be used without particular limitation as long as it has an aliphatic main chain that is not polyoxy.
[0016]
From the viewpoint of affinity with the polyolefin resin used as the matrix resin, the main chain of the epoxy group-containing resin is preferably an aliphatic resin having no polar part, and particularly a type having a relatively long aliphatic chain. Is more preferably used. Examples include epoxidized polybutadiene, aliphatic mono (di) glycidyl ether, dimer acid diglycidyl ester, dimer acid-modified BPA type epoxy resin, hydrogenated bisphenol A type diglycidyl ether, and aliphatic polyglycidyl ether. . Moreover, there is no restriction | limiting in particular also in an epoxy group, A glycidyl group, an alicyclic epoxy group, etc. can be used.
[0017]
In addition, the olefinic thermoplastic elastomer resin (compound c), which is a component of the sizing agent, has a relatively small molecular weight in the acid-modified polypropylene resin, and the acid-modified polypropylene resin alone cannot impart sufficient convergence to the carbon fiber bundle. This improves the problem and makes it possible to impart sufficient bundling and draping properties to the carbon fiber bundle. In addition, the olefinic thermoplastic elastomer resin can ensure sufficient affinity with the polyolefin matrix resin.
[0018]
Preferred olefin-based thermoplastic elastomers are those having a Vicat softening point of 120 ° C. or less, preferably 110 ° C. or less, more preferably 90 ° C. or less, measured according to ASTM D1525-70. In the step of attaching an aqueous sizing agent solution as a sizing agent to the carbon fiber bundle and then evaporating the water, the drying temperature is generally about 140 ° C., but at that time the olefinic thermoplastic elastomer resin is sufficiently softened. The better the convergence of the carbon fiber bundle after drying. Specific examples of such olefinic thermoplastic elastomer resins include GFE-1030 (water-based emulsion) manufactured by Yoshimura Oil Chemical Co., Ltd., TPO-M142, R110E, and T310E manufactured by Idemitsu Petrochemical Co., Ltd.
[0019]
The composition ratio of these three compounds of the sizing agent in the present invention is such that the compound a is 35% by mass or more based on the total weight of the sizing agent, Compound b Is 30% by mass or more, and compound c is preferably 20% by mass or more. As mentioned above, each compound plays an important role. Effective role The minimum abundance of each is determined for expression.
[0026]
On the other hand, as a resin (compound b) having an aliphatic main chain that is not polyoxy-based and containing an epoxy group, ethylene or a copolymer of propylene and an epoxy group-containing monomer (compound d), or ethylene or By using a copolymer (compound e) of propylene, an epoxy group-containing monomer, and an acrylate ester, a carbon fiber bundle having a polyolefin resin and better interfacial adhesion and convergence can be obtained.
[0027]
Furthermore, a silane coupling agent having an epoxy group, a vinyl group, an amino group, a methacryl group, an acrylic group or a linear alkyl group in the molecule can be added to the sizing agent. Moreover, a silane coupling agent may be used individually by 1 type, and 2 or more types can also be mixed and used for it. Among the silane coupling agents, epoxy silane, amino silane, and linear alkyl group are particularly preferable. In the epoxy silane system, the epoxy group of the silane compound is preferably a glycidyl group, an alicyclic epoxy group or the like, and as such a silane coupling agent, A-186, A-187, AZ manufactured by Nippon Unicar Co., Ltd. Specific examples thereof include -6137 and AZ-6165.
[0028]
Examples of aminosilanes include those having primary amines, secondary amines, or both. A-1100, A-1110, A-1120, Y-9669, A-1160, etc. manufactured by Nippon Unicar Co., Ltd. Is used. Examples of the linear alkyl group include those having a hexyl group, an octyl group, and a decyl group, such as AZ-6171, AZ-6177 manufactured by Nippon Unicar Co., Ltd., KBM-3103C manufactured by Shin-Etsu Silicone Co., Ltd. Specific examples.
[0029]
In the present invention, the silane coupling agent used for the treatment of the glass fiber reinforced composite material is used, but the silane coupling agent is a thermoplastic resin. Matrix resin In the carbon fiber reinforced composite material, the interfacial adhesive force is further improved. In addition, in glass fiber reinforced composite materials, it is considered to work effectively for affinity with glass fiber substrates, but in carbon fiber reinforced composite materials, it is used. Matrix resin Rather than the carbon fiber substrate Matrix resin It is inferred that it is effective in the interaction with.
[0030]
The addition amount of the silane coupling agent is 5% by mass or less, preferably 4% by mass or less with respect to 100% by mass of the total component amount (total solid content) other than water of the sizing agent. When the addition amount exceeds 5% by mass, the silane crosslinking of the silane compound proceeds, the bundled state of the carbon fiber bundle becomes hard and brittle, vertical cracks are likely to occur, and the interfacial adhesion may be further reduced. is there.
[0031]
The carbon fiber bundle of the present invention can be obtained by treating with a water-based sizing agent solution in which the constituent components of the sizing agent are dissolved or dispersed in water. In view of industrial production, it is preferable to use an aqueous sizing agent solution for safety and economy. For the purpose of dispersing the constituents of the sizing agent in water, a surfactant is used as an emulsifier. At this time, the emulsifier is not particularly limited, and an anionic, cationic, nonionic emulsifier, or the like can be used. Of these, anionic or nonionic emulsifiers are preferred. Further, when a silane coupling agent is added, a nonionic emulsifier is particularly preferable from the viewpoint of stability of the silane coupling agent in water and stability of physical properties of the fiber-reinforced thermoplastic resin material after molding.
[0032]
The method of attaching the sizing agent is not particularly limited. A touch roll method in which a part of the roll is immersed in the sizing agent and the surface is transferred, and then the carbon fiber bundle is brought into contact with the roll to attach the carbon fiber bundle. Examples include a dipping method in which the amount of adhesion is controlled by dipping directly in a sizing agent and then passing through a nip roll as necessary. In addition, the amount of the sizing agent attached to the carbon fiber bundle is not particularly limited. However, in a carbon fiber bundle having continuous fibers, the amount of the sizing agent attached to the carbon fiber bundle is 0.3 to 5 in terms of the amount of components other than water. It is preferably in the range of mass%.
[0033]
Next, the chopped carbon fiber bundle of the present invention is made by adhering the sizing agent solution, cutting it to a predetermined length, and drying it. The amount of the sizing agent attached to the carbon fiber bundle is 1 in terms of the amount of components other than water. More preferably, it is -5 mass%. The chopped carbon fiber bundle of the present invention has a carbon fiber bundle weight of 0.4 to 15 g / m, preferably 0.6 to 10 g / m, more preferably 0.8 to 8 g / m, and is cut. A chopped carbon fiber bundle having a fiber bundle width / thickness of 3 to 10 is preferable. When the basis weight of the carbon fiber bundle is less than 0.4 g / m, it is economically inconvenient, and further deteriorates the chopped carbon fiber bundle introduction process passability in the pellet manufacturing process. On the other hand, when it exceeds 15 g / m, it becomes difficult to allow the sizing agent to completely penetrate the carbon fiber bundle, and it becomes impossible to produce a chopped carbon fiber bundle having a stable shape.
[0034]
The production of the chopped carbon fiber bundle of the present invention is performed by a method in which an aqueous sizing agent is attached, cut to a predetermined length, and dried, and the sizing agent is added to the carbon fiber bundle in an amount of components other than water in an amount of 1 to 5 mass. %. If the amount of sizing agent attached is less than 1% by mass, sufficient convergence cannot be obtained in the subsequent cutting step and drying step, and fiber cracking and fluffing may occur, causing troubles when the extruder is introduced. On the other hand, if the adhesion amount exceeds 5% by mass, the focusing force becomes strong, and the subsequent process is easy to pass. However, it is difficult to uniformly disperse the resin in the extruder. There is a risk that mechanical properties are deteriorated due to dispersed spots.
[0035]
The attachment method of the sizing agent is not particularly limited, and a touch roll method in which a part of the roll is immersed in the sizing agent and the surface is transferred, and then the carbon fiber bundle is brought into contact with the roll, and the carbon fiber bundle is attached. May be directly dipped in the sizing agent, and then, if necessary, may be passed through a nip roll to control the amount of adhesion. Among them, the touch roll method is preferable, and a method in which the carbon fiber bundle is brought into contact with a plurality of touch rolls and adhered in a plurality of stages is particularly preferable from the viewpoint of controlling the amount of adhesion and the bundle width.
[0036]
After the sizing agent is attached to the carbon fiber bundle, the carbon fiber bundle in a wet state is subsequently cut into a chopped carbon fiber bundle. The cutting process utilizes the focusing effect of carbon fibers due to the surface tension of a sizing agent containing water and the absorption of shearing force at the time of cutting in a wet and soft state to prevent fiber cracking. . In the cutting process in the present invention, it is necessary to cut the carbon fiber bundle in a wet state in which the moisture content of the carbon fiber bundle is 20 to 60% by mass, preferably 25 to 50% by mass. If the moisture content is less than 20% by mass, there is a risk that fiber breakage and fluff are likely to occur during cutting. Also, if the moisture content exceeds 60% by mass, water is excessively attached to the fiber surface, so that the carbon fiber is rounded by the surface tension of the water, and the frequency of occurrence of miscuts and blade clogging during cutting. May increase. Moreover, in order to adjust a moisture content as needed, you may perform the additional adhesion process by water or a sizing agent before cutting | disconnection.
[0037]
Although there is no restriction | limiting in particular as a cutting system, A rotary cutter system etc. are suitable. The cutting length (chopped carbon fiber length) is 2 to 30 mm, preferably 4 to 24 mm, and more preferably 6 to 20 mm. In the rotary cutter method, the cutting length can be adjusted by adjusting the tooth tip interval of the apparatus to be used. When cutting with the rotary cutter method, if the fiber bundle thickness becomes too thick, the fiber bundle thickness will be cut, or the carbon fiber will be wrapped around the rotor, making it impossible to operate, and resulting in poor shape after cutting. Is more advantageous. Further, in the case of a thick-weight carbon fiber bundle having a basis weight of 1.5 g / m or more, it is important to open the carbon fiber bundle as much as possible and to uniformly attach the sizing agent to the inside of the fiber bundle. Therefore, the carbon fiber bundle after the sizing process is substantially controlled while controlling the bundle width / thickness of the carbon fiber bundle before and after the sizing process using a guide roll, a comb guide, a spreader bar, etc. It is preferable to run so that there is no twist.
[0038]
A chopped carbon fiber bundle that has been cut short is liable to be longitudinally cracked along the fiber orientation when the bundle width is widened, and it tends to be difficult to maintain its form during use or after use. This is particularly noticeable in thick-weight carbon fiber bundles, but the present inventors added a sizing agent having a large film strength, particularly a film elongation, by adding an elastomer component to the sizing agent component. The shape stability of the thick-weighted carbon fiber bundle can be effectively maintained.
[0039]
That is, it is preferable to control the bundle width so that the bundle width is extremely narrow so as not to have a circular cross section or an elliptical cross section, specifically, the bundle width / thickness is 3 or more, preferably 3 to 10. . Generation | occurrence | production of the miscut in the cutting process with a rotary cutter can be suppressed as bundle width / thickness is 3 or more. Further, if the bundle width / thickness exceeds 10, miscutting at the time of cutting becomes difficult to occur, but the thickness becomes too thin and carbon fiber bundles are liable to be longitudinally cracked after cutting, and the subsequent process passability deteriorates. There is a fear. In addition, in order to widen and cut thick carbon fiber bundles as thin as general-purpose types, the number of carbon fibers that can be processed at the same time decreases, and in order to compensate for the decrease, it is necessary to widen the cutter or increase the processing speed. As a result, there is a risk of reducing the load on the facility and the production efficiency.
[0040]
Therefore, it is preferable to control the bundle width of the carbon fiber bundle by adjusting the width of the guide attached to the rotary cutter so that the bundle width / thickness is 3 to 10. As a matter of course, the carbon fiber bundle has a wider width in the thick carbon fiber bundle, and the fiber bundle is folded in the guide of the rotary cutter. It is desirable to do.
[0041]
Next, the cut chopped carbon fiber bundle is dried, and examples of the drying method include a hot air drying method. When the hot air drying method is employed, it is preferable to perform drying while transporting in a vibrated state in order to improve moisture evaporation efficiency and prevent adhesion between chopped carbon fiber bundles. In addition, when the vibration at the time of drying is too strong, it becomes easy to generate | occur | produce a fiber crack, and the ratio of the chopped carbon fiber bundle whose bundle width / thickness is less than 3 increases. On the other hand, if the vibration is too weak, pseudo-bonding between the fibers occurs, resulting in a dumpling shape. Therefore, it is necessary to set an appropriate vibration condition. In addition to shaking the chopped carbon fibers, it is more preferable to vibrate and dry while transporting the mesh diaphragm to improve the flow of hot air. In order to improve the drying efficiency, auxiliary means such as infrared radiation can be used in combination.
[0042]
In the production of the chopped carbon fiber bundle of the present invention, the carbon fiber bundle to be sized may be already sized in the production process or may be sized. According to the present invention, it is possible to provide a chopped carbon fiber bundle that is excellent in shape stability and excellent in handleability during the production of a fiber-reinforced composite material. The present invention is particularly effective for obtaining a thick chopped carbon fiber bundle having a basis weight exceeding 1.5 g / m, and can stabilize the manufacturing process and improve the quality, and can be used for mass production. Thus, it is possible to provide a chopped carbon fiber bundle that is inexpensive and excellent in economic efficiency.
[0043]
A carbon fiber reinforced thermoplastic resin composition can be obtained by kneading with a thermoplastic resin as a matrix resin using the chopped carbon fiber bundle of the present invention. In kneading the chopped carbon fiber bundle into the thermoplastic resin, it is preferable to supply the chopped carbon fiber bundle to an extruder, knead with the thermoplastic resin, and pelletize the pellet. Moreover, the carbon fiber reinforced thermoplastic resin composition of the present invention can be molded by a known molding method such as an injection molding method to provide a molded product (fiber reinforced composite molded product) having an arbitrary shape.
[0044]
In preparing the thermoplastic resin composition of the present invention, the chopped carbon fiber bundle of the present invention is preferably blended in an amount of 3 to 60 mass%, preferably 5 to 50 mass%, based on the total weight of the composition. By blending 3% by mass or more of the chopped carbon fiber bundle, the effect of improving the mechanical properties of the molded product is remarkably exhibited. On the other hand, if it exceeds 60% by mass, no further significant improvement effect can be obtained, the process stability at the time of pellet production is lowered, the fiber content unevenness of the pellet is generated, and the quality stability of the molded product is deteriorated. There is a fear.
[0045]
The thermoplastic resin used as the matrix resin in the present invention is not particularly limited, but a polyolefin resin is optimal from the viewpoint of affinity with the olefin compound that is the main component of the sizing agent. Resin, ABS resin, AS resin, polyoxymethylene resin, polyphenylene sulfide resin, polyethersulfin resin, polyetherimide resin, nylon resin, polyester resin, and a resin selected from the group of these alloy resins preferable. In particular, when a polyolefin-based resin is used as a matrix, a small amount of various modified polyolefin resins may be added for the purpose of further improving mechanical properties.
[0046]
Since the molded article made of the carbon fiber reinforced thermoplastic resin composition of the present invention is obtained using the chopped carbon fiber bundle of the present invention, it is excellent in mechanical properties, and in productivity and economy.
[0047]
【Example】
Hereinafter, the present invention will be specifically described by way of examples.
[0048]
(Example 1-4 Comparative Examples 1 to 4)
[Polypropylene molded products]
Production of chopped carbon fiber bundles:
As a raw material carbon fiber bundle, a pyrofil TR30S-12L or TR30L-50L (carbon fiber bundle manufactured by Mitsubishi Rayon Co., Ltd.) made of 12,000 or 50,000 filaments using polyacrylic fiber as a precursor is used. A carbon fiber bundle was obtained by alternately passing through a fiber width regulating bar a plurality of times to obtain a predetermined carbon fiber bundle width and then performing a sizing treatment to attach a sizing agent. Sizing agent used Table 1 and Table 2 show the components and composition ratios, respectively. In using the sizing agent, the amount of water was adjusted and the concentration of the sizing agent was adjusted. In addition, as a method of attaching the sizing agent, after immersing a part of the roll in the sizing agent tank and transferring it to the roll surface, using the two touch rolls, the carbon fiber bundle is brought into contact with the roll surface. A touch roll method was adopted in which coating was performed on both the front and back surfaces of the carbon fiber bundle.
[0049]
[Table 1]
[0050]
[Table 2]
[0051]
In Table 2, the weight content of each component is the amount of the water-soluble or water-dispersible resin pure component based on the total amount of the sizing agent other than water of 100% by mass (% by mass), the silane coupling agent The addition amount means the addition amount (% by mass) with respect to the total component amount other than water of the sizing agent of the pure component of the silane coupling agent. Next, the carbon fiber bundle in a wet state is cut into a length of 6 mm using a rotary cutter, and finally, it is continuously put into a floor vibration type hot air drying furnace and dried at 150 ° C., thereby chopped carbon fiber. Got a bunch.
[0052]
Manufacture of pellets and molded products:
A polypropylene resin and a modified polypropylene resin are used in combination as a matrix resin, a chopped carbon fiber bundle is mixed with a polypropylene resin in the formulation shown in Table 3, and the mixture is supplied to a twin-screw extruder heated to 250 ° C. The fibrous filler was supplied to the molten resin by a side feeder and kneaded to obtain pellets.
[0053]
Each of the obtained pellets was produced using a screw in-line molding machine having a diameter of 20 mm and a diameter of 35 ounces at a cylinder temperature of 250 ° C. and a mold temperature of 60 ° C. Further, as the mechanical properties of the molded product, tensile properties and bending properties were measured in accordance with JIS K7113 and JIS K7203, respectively. In Table 3, each abbreviation represents the following.
PP: Polypropylene (Idemitsu Co., Ltd. J-5051HP)
Modified PP: Maleic anhydride copolymerized polypropylene (Masterbatch P503, manufactured by Mitsubishi Chemical Corporation)
[0054]
Table 3 shows the physical properties of the strands of the carbon fiber bundle, the sizing treatment conditions, the moisture content at the time of cutting, the appearance of the chopped carbon fiber bundle, and the cut length (fiber length of the chopped carbon fiber bundle). The strand physical properties of the carbon fiber bundle were measured according to JIS R7601. Moreover, the adhesion amount of the sizing agent was measured according to the extraction method of JIS R7601. Table 3 shows the evaluation results of the types of thermoplastic resins used in the pellet production, the blended amount of the chopped carbon fiber bundle, and the physical properties of the molded product. In Table 3, the sizing agent concentration is the total amount of components other than water (mass%) with respect to the total amount of the sizing agent, and the blending amount of the carbon fiber bundle at the time of pellet production is the blending amount (mass of the chopped carbon fiber bundle in the pellet). %).
[0055]
[Table 3]
[0056]
(Example 5-6 Comparative Examples 5-8)
[Polypropylene molded products and nylon molded products]
Example 1-4 In the same manner as in Comparative Examples 1 to 4, the sizing agent shown in Table 2 was used, the sizing agent concentration was 6% by mass, the tow width was 8 mm, the tow width / thickness ratio was 4, the sizing agent adhesion amount was 2.5% by mass, and the cutting. Using a chopped carbon fiber bundle having a cutting length of 6 mm obtained under conditions of a moisture content of 42% by mass, using polypropylene resin and nylon resin as matrix resins, respectively, and mixing them in the composition shown in Table 4, this mixture was 310 ° C. The mixture was supplied to a twin-screw extruder heated to 1 and the fibrous filler was supplied to the molten resin by a side feeder and kneaded to obtain pellets. Next, each molded product was produced from the pellets with a screw in-line molding machine having a diameter of 20 mm and a diameter of 35 ounces at a cylinder temperature of 310 ° C. and a mold temperature of 80 ° C. In Table 4, abbreviations represent the following.
PP: Polypropylene (Idemitsu Co., Ltd. J-5051HP)
N66: Nylon 66 (Mitsubishi Engineering Plastics Novamid 3010SR)
[0057]
Table 4 shows the carbon fiber bundles used, types of sizing agents, and sizing treatment conditions. In addition, the measurement of the physical property of the strand of the carbon fiber bundle and the adhesion amount of the sizing agent was performed in the same manner as in Examples 1 to 9, and the blended amount of the chopped carbon fiber bundle used at the time of pellet production and the evaluation of the physical property of the molded product The results are shown in Table 4. In Table 4, the sizing agent concentration is the total amount of ingredients other than water (% by mass) relative to the total amount of the sizing agent, and the amount of carbon fiber bundles at the time of pellet production means the amount of chopped carbon fiber bundles (% by mass) in the pellets. To do.
[0058]
[Table 4]
[0059]
(Example 7-8 )
In Example 1, Pyrofil TR40 or MR40 (carbon fiber bundle manufactured by Mitsubishi Rayon Co., Ltd.) made of 12,000 filaments using polyacrylic fiber as a precursor is used as a raw material carbon fiber bundle, and the sizing agent is shown in Table 2. A polypropylene-based molded product was prepared in the same manner as in Example 1 except that the sizing agent E was used. Table 5 shows the evaluation results of the physical properties of the molded product.
[0060]
[Table 5]
[0061]
【The invention's effect】
According to the present invention, it is possible to provide a carbon fiber bundle that is excellent in affinity with a thermoplastic resin, particularly a polyolefin resin, and excellent in mechanical properties of a carbon fiber reinforced resin molded product, and further excellent in shape stability. It is possible to provide a chopped carbon fiber bundle that is excellent in handling at the time of manufacturing a fiber-reinforced composite material and excellent in economic efficiency. In addition, the present invention is suitable for a thick-weight carbon fiber bundle having a basis weight of 1.5 g / m or more, and can stabilize the production process and improve the quality. Since the molded article made of the carbon fiber reinforced thermoplastic resin composition of the present invention is obtained using the chopped carbon fiber bundle of the present invention, it is excellent in mechanical properties, and in productivity and economy.

Claims (12)

An acid-modified polypropylene resin (compound a) whose carbon fiber has a number average molecular weight of 20,000 or less and an acid value measured according to ASTM D1386 of 23 to 120 mgKOH / g, an aliphatic main chain which is not polyoxy-based A carbon fiber bundle characterized by being converged with a sizing agent comprising a resin (compound b) having an epoxy group and an olefin-based thermoplastic elastomer resin (compound c) as constituent components.   The carbon fiber bundle of Claim 1 converged with the sizing agent containing 35 mass% or more of compound a, 30 mass% or more of compound b, and 20 mass% or more of compound c with respect to the sizing agent total mass.   The carbon fiber bundle according to claim 1 or 2, wherein the compound c is a compound having a Vicat softening point of 120 ° C or lower measured according to ASTM D1525-70. Resin (compound b) having an aliphatic main chain that is not a polyoxy group and containing an epoxy group is a copolymer of ethylene or propylene and an epoxy group-containing monomer (compound d), or contains ethylene or propylene and an epoxy group The carbon fiber bundle according to any one of claims 1 to 3 , which is a copolymer (compound e) of a monomer and an acrylate ester. Sizing agent, epoxy groups in the molecule, vinyl group, amino group, methacryl group, of claims 1 to 3 containing 5 wt% or less with respect to the sizing agent to the total mass of a silane coupling agent having an acryl group or a straight-chain alkyl group The carbon fiber bundle as described in any one. The sizing agent according to any one of claims 1 to 3 is attached to a carbon fiber bundle and cut into a predetermined length, and the amount of the sizing agent attached to the carbon fiber bundle is 1 to 4 in an amount of components other than water. A chopped carbon fiber bundle of 5% by mass. The chopped carbon fiber bundle according to claim 6 , wherein the basis weight of the carbon fiber bundle is 0.4 to 15 g / m and the fiber bundle width / thickness at the time of cutting is 3 to 10. A method for producing a chopped carbon fiber bundle, wherein the sizing agent according to any one of claims 1 to 3 is attached to a carbon fiber bundle, cut to a predetermined length, and dried. A method for producing a chopped carbon fiber bundle, wherein a sizing agent is attached in an amount of 1 to 5% by mass in a component amount other than water, and the carbon fiber bundle is cut in a wet state with a moisture content of 20 to 60% by mass. The method for producing a chopped carbon fiber bundle according to claim 8, which is used as an aqueous sizing agent solution in which a sizing agent is dissolved or dispersed in water. The carbon fiber reinforced thermoplastic resin composition which mix | blended 3-60 mass% with the amount of carbon fibers of the carbon fiber bundle or chopped carbon fiber bundle as described in any one of Claims 1-7 in the thermoplastic resin. The thermoplastic resin is polyolefin resin, polycarbonate resin, ABS resin, AS resin, polyoxymethylene resin, nylon resin, polyphenylene sulfide resin, polyethersulfin resin, polyetherimide resin, polyester resin, and alloy resins thereof. The carbon fiber reinforced thermoplastic resin composition according to claim 10 , which is at least one selected from the group consisting of: A molded article formed by molding the carbon fiber-reinforced thermoplastic resin composition according to claim 10 or 11 .