JP2010229211A - Prepreg for fiber reinforced composite material and molded product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg which has good process passing properties and good moldability and a process for producing the same. <P>SOLUTION: The prepreg includes reinforced fibers and epoxy resin compositions, and an epoxy resin composition [A] having a viscosity at 25°C of 1.0×10<SP>5</SP>to 1.0×10<SP>9</SP>Pa s and a glass transition temperature of 7-15°C is present on both surfaces in the thickness direction of the prepreg, and an epoxy resin composition [B] having a viscosity at 25°C of 5.0×10<SP>2</SP>to 1.0×10<SP>5</SP>Pa s is present in the center in the thickness direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a prepreg that provides excellent mechanical properties such as high strength, high elastic modulus and high toughness when laminated on a composite while having excellent handling properties and process passability, and a method for producing the same.

  For the production of fiber reinforced composite materials using carbon fibers or aramid fibers as reinforcing fibers, a method using a prepreg, which is a sheet-like intermediate base material in which reinforcing fibers are impregnated with an uncured thermosetting resin composition, is generally used. Is. In such a method, after a prepreg is laminated, a molded product of a fiber reinforced composite material is obtained by curing by heating. The fiber-reinforced composite material produced in this way is used for various general industrial applications such as tennis rackets, golf shafts, fishing rods, etc., but because it has high specific strength and specific rigidity, it requires particularly light weight. It is attracting attention as a structural material for aircraft.

As a prepreg lamination method, a hand lay-up method, ATL (Automated)
Tape Laying method, AFP (Automated Fiber)
However, when manufacturing large composite materials such as aircraft, it is possible to dramatically improve productivity, so automatic lamination methods such as the ATL method and the AFP method are used (for example, patents). Reference 1). Above all, the AFP method employs a method of laminating slit tape prepregs obtained by cutting the prepreg into a tape shape in the fiber direction, and is suitable for manufacturing parts with relatively curved surfaces such as aircraft fuselage, and minimizes prepreg defects. Since it can be suppressed, it has become a widely used method in recent years.

  Since the AFP method can improve the lamination efficiency, there is a process of focusing about 10 to several hundred narrow prepregs with a width of 2 to 13 mm. The prepreg is guided to a guide and gathered on a machine head to form a mandrel. However, there is a problem in that the resin and the like fall off due to rubbing between the guide and the tape and the process passability is lowered. In order to prevent the epoxy resin composition impregnated in the prepreg from dropping out and adhering to the guide, and at the same time to ensure adhesion during winding, the process is performed under low temperature conditions where the viscosity of the epoxy resin composition is higher when the prepreg is unwound. For example, it is carried out at a temperature of 10 ° C. or lower, and the temperature is often increased at the time of winding.

  The prepreg used in the AFP basically includes a yarn prepreg method in which carbon fibers are impregnated with a resin in units of strands such as 12,000 or 24000, and the width is fixed and wound, and once a wide prepreg is used. There is a slit tape method in which the film is slit into a predetermined width in the width direction and wound up. Patents that specify that the softening point of the resin is −5 ° C. to 25 ° C. when a narrow tape prepreg is produced by the former method are known. (Patent Document 2) Here, the softening point of the resin is defined for the purpose of keeping the tape width at the time of molding constant, and the impregnation property for producing the yarn prepreg is examined, but the fallout is prevented. In order to do this, further examination of the softening point and viscosity adjustment are required.

  Moreover, in patent document 3, in order to improve the winding property of a yarn prepreg and to ensure drape property, the viscosity range of the thermosetting resin to be used shall be 3000-100000 poise, More preferably, 5000-40000 poise. Is described. Patent Document 4 states that the viscosity of the thermosetting resin needs to have fluidity at the temperature at the time of impregnation, and the viscosity range as a measure of fluidity is 1 to 1,000,000. A centipoise is preferred, and more preferably 1 to 10,000 centipoise. However, in these inventions, there is a problem that drape and impregnation are deteriorated when the resin composition is adjusted in order to prevent falling off.

In addition, usually a resin having a viscosity at room temperature of several Pa.s is used for the yarn prepreg, but in those prepregs, there are many resin dropping off in the process, so in the yarn prepreg containing the cationic polymerizable resin composition, using a yarn prepreg viscosity at 30 ° C. is viscosity at ^{1 × 10 4 ~1 × 10 6} Pa · s, 80 ℃ characterized in that it is a 1~300Pa · s, activates the resin during or after molding or molding A technique is disclosed (Patent Document 5). According to this technique, although an effect is observed in dropping off the resin, special equipment and conditions for activating the resin are required.

Furthermore, in the yarn prepreg, an epoxy resin composition having a glass transition point of −25 ° C. to 20 ° C. of the matrix resin is used, and the epoxy resin contains a resin of tetraglycidyldiaminodiphenylmethane type as a constituent component, and the heat contained uniformly in the matrix It is disclosed that it preferably contains a plastic resin and thermoplastic resin particles that do not dissolve in the matrix, and the compressive strength after impact is preferably 130 MPa or more. (Patent Document 6)
However, with such a design, a good composite property can be obtained, but the yarn prepreg becomes hard if the resin composition is adjusted or the process temperature is adjusted in order to prevent falling off during AFP molding. Thus, there is a problem that the sticking property to the mandrel and the shape following property are insufficient, and conversely, when trying to improve these, there is a problem that the fallen objects increase.
In order to reduce the adhesion amount of the epoxy resin composition to the guide in the AFP method, the viscosity of the resin composition at the use temperature in the AFP method is preferably high. On the other hand, from the viewpoint of handling properties, it takes a lot of time to manufacture large laminates such as aircraft, so in addition to the appropriate tack and drape properties required for prepreg lamination, laminated prepreg In order to maintain adhesion between each other, it is preferable to have an excellent tack life. Further, in the prepreg production, the viscosity of the resin composition is low in a relatively high temperature range in which the epoxy resin composition is flowed during the heating / pressurizing process and impregnated into the unimpregnated reinforcing fibers. Is preferred. From this point of view, the yarn prepreg usually subjected to the AFP process is cooled in advance or unwound through a guide in a low-temperature atmosphere, and after making an effort to prevent falling off, preferably improve the winding property around the prepreg or mandrel. Therefore, it is laminated after being heated. In this case, the cooling temperature is normal temperature or lower, preferably 15 ° C. or lower, more preferably 5 to 10 ° C. However, even if such conditions are selected, it is not always easy for conventional resins to satisfy the above-mentioned resin viscosity requirements at the same time. With conventional prepregs, the guide to the epoxy resin composition impregnated in the prepreg is not easy. There was a problem that productivity dropped due to a large amount of dropout and adhesion, requiring frequent cleaning.

Regarding the prepreg resin, several studies have been conducted on prepregs in which the resin composition is changed in the thickness direction. Patent Document 7 is selected from the group consisting of an epoxy resin, an aromatic amine curing agent, an acid anhydride curing agent, a dicyandiamide curing agent, and a novolac curing agent for the purpose of high quality in honeycomb cocure molding. An epoxy resin composition comprising one or more curing agents and a solid rubber, wherein the complex viscosity η _0.02 measured at a vibration frequency of _0.02 Hz at 80 ° C. is 5000 poise or more, and the vibration frequency is 2 Hz. The epoxy resin composition characterized in that the relationship between the complex viscosity η ₂ measured in step 1 and the complex viscosity η _0.02 measured at the vibration frequency of _0.02 Hz satisfies log η _0.02 −log η ₂ ≧ 0.5 A prepreg composed of epoxy resin compositions having different viscosities between the surface layer and the inner layer, measured at a vibration frequency of 0.02 Hz at 80 ° C. of the epoxy resin composition of the surface layer And complex viscosity eta _0.02 is 40,000 to 400,000 poise, and wherein the complex viscosity eta _0.02 measured at a vibration frequency 0.02Hz at 80 ° C. of the inner layer of the epoxy resin composition is less than 5000 poise to 40,000 poise Although this prepreg is disclosed, this configuration has no effect in preventing the resin from falling off, which is the object of this patent.

  In the yarn prepreg, the reinforcing fiber bundle is impregnated with a thermosetting resin having a glass transition point higher than 10 ° C. of the B stage, and the glass transition point of the B stage is impregnated with the thermosetting resin impregnated fiber bundle. A yarn prepreg characterized by being further impregnated with a thermosetting resin having a temperature of −10 to 10 ° C. is provided, and a device that achieves both windability and unwinding property is seen (Patent Document 8). . However, this configuration was not effective in preventing the resin from falling off, which is the object of this patent.

  Furthermore, the outer layer of the prepreg is provided in order to provide a structure that is significantly improved with respect to the strength other than the direction of the reinforcing fiber, that is, the non-fiber axis tensile strength and the compressive strength after impact, while ensuring the adhesiveness and flexibility of the prepreg. Discloses the localization of spherical fine particles made of resin (Patent Document 9). However, this configuration was not effective in preventing the resin from falling off, which is the object of this patent.

Special table 2008-517810 JP 2000-191807 A JP 09-012220 A Japanese Patent Application Laid-Open No. 09-169861 JP 2007-297487 A JP-A-11-130882 JP 05-239317 A JP 62-116638 A Japanese Patent Laid-Open No. 01-110537

  The problem to be solved by the present invention is to provide a prepreg in which adhesion of resin to a guide in the AFP method is reduced while maintaining excellent handling properties, process passability, lamination properties, and composite performance.

That is, the present invention is a prepreg composed of reinforcing fibers and an epoxy resin composition, and has a viscosity at 25 ° C. of 1.0 × 10 ^{5 to} 1.0 × 10 ⁹ Pa · on both surface sides in the thickness direction of the prepreg. s and present epoxy resin composition a glass transition temperature of 7 to 15 ° C. [a] is in the center of the thickness direction, × viscosity at 25 ° C. is 5.0 ¹⁰ 2 ~1.0 × ¹⁰ 5 Pa A prepreg characterized by the presence of the epoxy resin composition [B] as s.

Moreover, it is preferable that the viscosity in 80 degreeC of the epoxy resin composition [A] used for the prepreg of this invention is 100-1000 Pa.s.
Furthermore, the epoxy resin composition [A] used for the prepreg of the present invention is a bifunctional epoxy resin having an epoxy equivalent of 800 to 3000 g / eq, and 100 weights of all epoxy resins contained in the epoxy resin composition [A]. It is preferable to contain 5-25 weight part with respect to a part.

  Moreover, it is preferable that the prepreg of this invention is what the reinforcing fiber arranged in one direction in the longitudinal direction.

  Moreover, the above-described prepreg is cut into a strip shape in parallel with the reinforcing fiber arrangement direction to provide a slit tape prepreg.

  Furthermore, a composite material obtained by laminating and molding a slit tape prepreg on a mandrel is provided.

Further, the reinforcing fiber was impregnated with an epoxy resin composition [B] having a viscosity at 25 ° C. of 5.0 × 10 ^{2 to} 1.0 × 10 ⁵ Pa · s to prepare a primary prepreg, and then continuously, Alternatively, the primary prepreg that has been wound up is unwound and an epoxy resin composition having a viscosity at 25 ° C. of 1.0 × 10 ^{5 to} 1.0 × 10 ⁹ Pa · s and a glass transition temperature of 7 to 15 ° C. A method for producing a prepreg characterized by impregnating [A] from both sides is provided.

  According to the present invention, since the viscosity of the epoxy resin composition [A] on the prepreg surface layer is sufficiently high, adhesion of the resin to the guide in the AFP method can be reduced, and consequently the productivity of the fiber-reinforced composite material can be improved. It becomes possible. Moreover, since the viscosity of the epoxy resin composition [B] present on the inner side of the prepreg is sufficiently low, it has excellent drape properties. Furthermore, since the resin [B] is sufficiently present at the center in the thickness direction of the prepreg and the viscosity of the epoxy resin composition [A] existing on the surface side in the thickness direction of the prepreg is sufficiently high, the resin [A ] To the reinforcing fiber and has an excellent tack life, it is possible to provide a prepreg with good handling properties.

Epoxy resin composition used in the prepreg of the present invention [A], the viscosity at 25 ° C., to essential and that it is ^{1.0 × 10 5 ~1.0 × 10 9} Pa · s. More preferably, it is 1.0 * 10 < ⁶ > -1.0 * 10 < ⁸ > Pa * s. If it is lower than 1.0 × 10 ⁵ Pa · s, the amount of liquid or semi-solid resin adhering to the guide in the AFP method increases, the cleaning frequency is high and productivity decreases, and the viscosity is low, Deterioration of work efficiency due to excessive tack and deterioration of tack life due to sinking of resin are caused. When it is higher than 1.0 × 10 ⁹ Pa · s, the resin powder is generated on the surface of the prepreg when the prepreg is scraped to the guide, and it is necessary to clean the resin powder that has fallen off. In addition, since the viscosity is high, the tack / draping property is low and the handling property is also impaired.

  Here, the viscosity at 25 ° C. is simply determined by using a dynamic viscoelasticity measuring device (for example, rheometer RDA2: manufactured by Rheometrics Co., Ltd.) using a parallel plate at a rate of temperature increase of 2 ° C./min from 20 ° C. The viscosity at 25 ° C. is read from a viscosity curve obtained by measuring the temperature at a temperature of 100%, a frequency of 0.5 Hz, and a plate interval of 1 mm.

  Moreover, it is essential that the epoxy resin composition [A] used for the prepreg has a glass transition temperature of 7 to 15 ° C. For the same reason as described above, if the temperature is lower than 7 ° C., the resin is processed while being soft in the AFP method, so that the amount of the resin adhering to the metal guide is increased, and the tack is excessive and the tack life due to low viscosity. Become worse. When the temperature is higher than 15 ° C., when the prepreg is rubbed against a metal guide, the glass-like prepreg resin generates resin powder, and the tack / drape property is further deteriorated due to high viscosity. Here, AFP is preferably processed at a temperature lower than room temperature, for example, 15 ° C. or lower, more preferably 10 ° C. or lower and 0 ° C. or higher, in order to prevent the prepreg from falling off the resin. Although AFP can be performed at 0 ° C. or lower, the resin becomes too hard, so that solid falloff increases or a device for preventing condensation is required.

  In addition, the glass transition temperature said here is the midpoint temperature obtained based on JISK7121 (1987) using the differential calorimeter (DSC).

In order to achieve both handling properties, process passability, lamination properties and composite properties, all epoxy resins 100 contained in the epoxy resin composition [A] are prepared by using bifunctional epoxy resins having an epoxy equivalent of 800 to 3000 g / eq. It is preferable to mix 5 to 25 parts by weight with respect to parts by weight. When the epoxy equivalent is lower than 800 g / eq, the glass transition temperature and the viscosity are lowered, and when it is 3000 g / eq or more, the heat resistance of the molded product is lowered.
Furthermore, the epoxy resin composition [A] used in the prepreg of the present invention requires that the resin be localized on the surface side in the thickness direction of the prepreg in the prepreg formed by impregnating the resin with reinforcing fibers. It is.

In addition, the prepreg of the present invention has an epoxy resin composition in which the viscosity of the matrix resin at 25 ° C. is 5.0 × 10 ^{2 to} 1.0 × 10 ⁵ Pa · s in order to give the prepreg moderate drapeability. It is necessary to make [B] exist in the central part in the thickness direction of the prepreg. As a means for causing the epoxy resin composition [B] to be present in the central portion in the thickness direction of the prepreg, a release paper sheet with a resin film (hereinafter referred to as an epoxy resin composition [B]) coated on a release paper or the like in advance. It may be simply referred to as “resin film”), and then reinforced by heating and pressurizing the resin film surface of the release paper sheet with the resin film on both sides or one side of the reinforcing fiber with the resin fiber side facing up. A method of preparing a primary prepreg in which a fiber is impregnated with a resin composition, and then impregnating the epoxy resin composition [A] from both sides of the primary prepreg in the same manner as when the primary prepreg is prepared. Can be preferably used. The primary prepreg may be wound once and then unwound and impregnated with the epoxy resin composition [A], or the reinforcing fiber is impregnated with the epoxy resin composition [B] to obtain a primary prepreg. Immediately thereafter, the epoxy resin composition [A] may be impregnated. By setting it as the form of this prepreg, since the viscosity of the epoxy resin composition [B] which exists in the center part of a prepreg thickness direction is low enough, the outstanding drape property can be obtained. When the viscosity is lower than 5.0 × 10 ² Pa · s, the epoxy resin composition [A] tends to sink into the center of the prepreg, the tack life is impaired, and the viscosity is 1.0 × 10 ⁵ Pa · s. If it exceeds, drapability is impaired. From this viewpoint, the viscosity of the resin composition [B] is preferably 5.0 × 10 ^{2 to} 2.0 × 10 ⁴ Pa · s. Further, from the viewpoint of drape and tack life, the presence range of the epoxy resin composition [B] in the central part in the prepreg thickness direction is preferably in the range of 30 to 90% of the prepreg thickness, and 50 to 70%. If it is a range, it is more preferable.

  Furthermore, it is preferable that the viscosity at 80 ° C. of the epoxy resin composition [A] is 100 to 1000 Pa · s from the viewpoint of moldability, particularly impregnation into the primary prepreg. More preferably, it is 300-600 Pa.s. When the viscosity at 80 ° C. is lower than 100 Pa · s, the impregnation property is good, but the resin is easy to flow, and when the release paper sheet with the resin film is stacked and pressed to form a prepreg, from the end of the release paper sheet Since the resin flows and the prepreg processability deteriorates, it is not preferable. When the viscosity at 80 ° C. is higher than 1000 Pa · s, when the prepreg is sandwiched between the resin films coated with the epoxy resin composition [A] on the release paper and impregnated by heating and pressurizing using a press roll. This is not preferable because the resin remains on the resin film, so-called “backing” occurs, and the prepreg processability and quality deteriorate.

  Here, the viscosity at 80 ° C. is simply determined by using a dynamic viscoelasticity measuring device (for example, rheometer RDA2: manufactured by Rheometrics), using a parallel plate and starting at 20 ° C. at a rate of temperature increase of 2 ° C./min. The viscosity at 80 ° C. is read from a viscosity curve obtained by measuring the temperature at a temperature of 100%, a frequency of 0.5 Hz, and a plate interval of 1 mm.

  As the epoxy resin of the epoxy resin compositions [A] and [B] used for the prepreg of the present invention, an epoxy resin having an amine, a phenol, or a compound having a carbon / carbon double bond as a precursor is particularly preferable.

  Specific examples of the epoxy resin having amines as a precursor include tetraglycidyldiaminodiphenylmethanes, glycidyl compounds of aminophenol, glycidylanilines, and glycidyl compounds of xylenediamine. Tetraglycidyldiaminodiphenylmethanes are preferable because they are excellent in heat resistance as a composite material resin for aircraft structural materials.

Examples of epoxy resins having phenols as precursors include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, and resorcinol type epoxy resins. In particular, bifunctional bisphenol A type epoxy resins and bisphenol F type epoxy resins can be more preferably used in the present invention because the rate of decrease in viscosity on the high temperature side is relatively high.
Examples of the epoxy resin using a compound having a carbon / carbon double bond as a precursor include polycyclic epoxy resins.

  These epoxy resins may be used singly or may be appropriately mixed and used. A combination of a glycidylamine type epoxy resin and a bifunctional glycidyl ether type epoxy resin is particularly preferable because it has both heat resistance, water resistance and workability.

  Examples of the curing agent for the epoxy resin compositions [A] and [B] used in the prepreg of the present invention include aromatic amines, dicyandiamide, and dibasic acid dihydrazide alone or in a mixed system. Examples of aromatic amines include metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and metaxylenediamine.

  These curing agents may be used alone or may be appropriately blended and used. Aromatic amines are particularly preferred because they can impart heat resistance to the cured resin. The addition amount is preferably from the viewpoint of imparting heat resistance, so that the addition amount is 0.7 to 1.2 equivalent to the epoxy in the stoichiometry of the epoxy group of the epoxy resin and the active hydrogen of the aromatic amine.

  The epoxy resin compositions [A] and [B] used for the prepreg of the present invention include organic particles such as rubber particles and thermoplastic resin particles, liquid thermosetting resins other than epoxy resins, curing accelerators, flame retardants, One or more silane coupling agents and soluble thermoplastic resins can be contained. From the viewpoint of controlling the viscosity of the epoxy resin composition and improving the impact resistance of the composite material, organic particles such as thermoplastic resin particles and soluble thermoplastic resins can be more preferably used.

  Examples of the rubber particles include cross-linked rubber particles and core-shell rubber particles obtained by graft polymerization of a different polymer on the surface of the cross-linked rubber particles.

  As the thermoplastic resin particles, acrylic particles, polyamide particles, polyimide particles, and polyetherimide particles are preferably used.

  Examples of liquid thermosetting resins other than epoxy resins include cyanate ester resins, bismaleimide resins, and benzoxazine resins.

  Soluble thermoplastic resin refers to a thermoplastic resin that is mixed macroscopically and uniformly with epoxy resin when kneading with normal temperature set higher than normal temperature when compounding epoxy resin. Including those that separate into fine phases when they are returned to, and those that maintain a uniform phase, specifically, polyethersulfone, polysulfone, polyimide, polyetherimide, polycarbonate, polyetherethersulfone, poly vinyl formal, poly Methyl methacrylate and the like are preferably used.

  The ratio of the epoxy resin composition [A] and [B] is preferably in the range of 1: 9 to 7: 3, particularly preferably in the range of 3: 7 to 5: 5. When the ratio [A] is lower than 1: 9, the drop-off preventing effect is small, and when the ratio [A] is higher than 7: 3, the drape of the prepreg is impaired.

  The prepreg of the present invention comprises the above-described epoxy resin composition and reinforcing fibers. Examples of the reinforcing fiber include glass fiber, Kevlar fiber, carbon fiber, graphite fiber, and boron fiber. Of these, carbon fibers and graphite fibers are preferable in terms of specific strength and specific elastic modulus.

  The prepreg used in the AFP method may be one produced by the yarn prepreg method, but the slit tape prepreg cut in the fiber direction is impregnated with an epoxy resin composition impregnated in a reinforcing fiber bundle aligned in one direction. It is excellent in accuracy and preferable. The width of the slit tape prepreg is preferably 2 to 150 mm, but is preferably 2 to 15 mm in the AFP method for producing a member having a complicated shape. Further, a slit tape prepreg having a narrow width of 3 to 7 mm is more preferable.

  Specific arrangement of these resins on the center in the prepreg thickness direction (sometimes referred to as the prepreg inner layer) and both surfaces in the thickness direction of the prepreg (sometimes referred to as the prepreg outer layer) (ie, the epoxy resin composition mainly in the outer layer) In order to obtain a primary prepreg, the reinforcing fiber is first impregnated with the epoxy resin composition [B]. It can be prepared by impregnating the epoxy resin composition [A]. At that time, in order to prevent excessive mixing of the epoxy resin compositions [A] and [B], it is preferable to adjust the temperature, tension, impregnation pressure of the prepreg and the like when impregnating [A]. In particular, it is more preferable to set the temperature and pressure when impregnating [A] to be lower than when impregnating [B] to prevent mixing of both resins.

  The composite material of the present invention can be produced by heat-molding a laminate in which a plurality of prepregs of the present invention are laminated in an oven. At this time, pressure may be applied as necessary. In addition, a plurality of slit tape prepregs obtained by cutting the prepreg into strips parallel to the arrangement direction of the reinforcing fibers are prepared, laminated on a mandrel by the AFP method, the periphery is sealed with a bag material, and the sealed laminate is vacuum-released. It is preferable to manufacture by heating and pressurizing from outside.

  Hereinafter, the present invention will be described more specifically with reference to examples.

In this example, the viscosity at 25 ° C. and 80 ° C. is 20 using a dynamic viscoelasticity measuring device (Rheometer RDA2: manufactured by Rheometrics), a parallel plate, and a heating rate of 2 ° C./min. The temperature was simply raised from 0 ° C., measured at a strain of 100%, a frequency of 0.5 Hz, and a plate interval of 1 mm, and the viscosity at 25 ° C. and 80 ° C. was read from the obtained viscosity curve.
The tack was cut to 100 mm width and 200 mm length, and 18 mm × 18 mm glass was pressed with a load of 0.1 kg for 3 seconds on the surface of the prepreg that was affixed to a flat aluminum plate with double-sided tape, then 30 mm The force when pulling up at a speed of 1 min was measured. The measurement environment is 24 ° C. and 50 RH%. When the tack is 1.8 to 2.4N, the prepregs are suitable for sticking. However, when the tack is higher than 2.4N, it is difficult to peel off. .

  The tack life was defined as the number of days that decreased by 1.0 N or more from the initial tack of the measurement.

  Further, in this example, the glass transition temperature was an intermediate temperature determined based on JIS K7121 (1987) using a differential calorimeter (DSC).

  In addition, when a slit tape prepreg slit to 1/4 inch width by the AFP method is used, the epoxy resin composition impregnated in the prepreg falls off to the guide. The tension applied to the slit tape prepreg increases. Thereby, when the slit tape prepreg was bent or the width of the slit tape prepreg was narrowed, the AFP device was cleaned.

In this example, the prepreg was produced as follows. After kneading the epoxy resin compositions [A] and [B] with a kneader, the epoxy resin compositions [A] and [B] kneaded on the release paper coated with silicone were uniformly applied to obtain a resin film. . A carbon fiber (T800SC-24K-10E manufactured by Toray Industries, Inc.) that is uniformly drawn between the resin films coated with the epoxy resin composition [B] is sandwiched, heated and pressurized using a press roll, and then carbon fiber. A primary prepreg impregnated with an epoxy resin composition [B] was obtained (carbon fiber weight 190 g / cm 2, resin content 25%). After the primary prepreg was impregnated with the epoxy resin composition [B], both release papers were peeled off. Next, the primary prepreg is sandwiched between the resin films coated with the epoxy resin composition [A], heated and pressurized using a press roll, and the primary prepreg is impregnated with the epoxy resin composition [A]. A prepreg was obtained (carbon fiber weight 190 g / cm 2, resin content 35%). At this time, the condition for impregnating the epoxy resin composition [A] is set to a lower pressure than the impregnation condition for the epoxy resin composition [B] in order to avoid mixing with the epoxy resin composition [B] as much as possible. The resin composition [A] was localized on both surface sides of the prepreg. The prepreg was wound into a roll after peeling off one release paper.
Example 1
As epoxy resin composition [A], ELM434 (Sumitomo Chemical Co., Ltd .: epoxy equivalent 120 g / eq) 80 parts by weight, jER1055 (Japan Epoxy Resin Co., Ltd .: epoxy equivalent 800-900 g / eq) 20 parts by weight, 4, 30 parts by weight of 4′-DDS (manufactured by Sumitomo Chemical Co., Ltd.), 14 parts by weight of Sumika Excel (registered trademark) 5003P (manufactured by Sumitomo Chemical Co., Ltd.), and 50 parts by weight of MP1001 (manufactured by Nippon Synthetic Rubber Co., Ltd.) were used.
As an epoxy resin composition [B], 80 parts by weight of ELM434, 20 parts by weight of jER819 (manufactured by Japan Epoxy Resin Co., Ltd .: epoxy equivalent 180 to 220 g / eq), 30 parts by weight of 4,4′-DDS, Sumika Excel ( 5 parts by weight of registered trademark 5003P was used.
The viscosity at 25 ° C. of the epoxy resin composition [A] was 3 × 10 ⁷ Pa · s, the viscosity at 80 ° C. was 500 Pa · s, and the glass transition temperature was 10 ° C. The viscosity of the epoxy resin composition [B] at 25 ° C. was 2 × 10 ⁴ Pa · s.

The prepreg had a tack of 2.0 N and a tack life of 10 days or longer. The drapeability at room temperature was good. In addition, the number of cleanings when the prepreg was slit to a predetermined width and 16 pieces were combined and used continuously for 2000 m by the AFP method was as good as 1 time.
(Example 2)
As the epoxy resin composition [A], except that Sumika Excel (registered trademark) 5003P was changed from 14 parts by weight to 11 parts by weight, the same composition as in Example 1 was used. As the epoxy resin composition [B], The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 1 × 10 ⁶ Pa · s, the viscosity at 80 ° C. was 250 Pa · s, and the glass transition temperature was 9 ° C.

The prepreg had a good tack of 2.4 N. However, since a softer resin exists on the surface side of the prepreg, the resin on the surface side of the prepreg sinks into the inner layer of the prepreg. Although it deteriorated, it was a level without any problem. The drapeability at room temperature was good. Further, since a soft resin was present on the prepreg surface side, the amount of the resin dropped off increased, but the number of cleanings when the prepreg was similarly used continuously for 2000 m by the AFP method was as good as 2 times.
Example 3
As the epoxy resin composition [A], except that Sumika Excel (registered trademark) 5003P was changed from 14 parts by weight to 16 parts by weight, the same composition as in Example 1 was used. As the epoxy resin composition [B], The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 2 × 10 ⁸ Pa · s, the viscosity at 80 ° C. was 850 Pa · s, and the glass transition temperature was 11 ° C.

The prepreg had a good tack life of 10 days or more, but because of the presence of a harder resin on the prepreg surface side, the tack was somewhat low at 1.5 N and was slightly difficult to stick (workability was slightly reduced). However, it was a level with no problem in use). The drapeability at room temperature was good. Similarly, when the prepreg was continuously used for 2000 m by the AFP method, the resin powder generated on the surface of the prepreg was dropped, but the number of cleanings was 2 times.
Example 4
As the epoxy resin composition [A], except that Sumika Excel (registered trademark) 5003P was changed from 14 parts by weight to 9 parts by weight, the same composition as in Example 1 was used. As the epoxy resin composition [B], The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 2 × 10 ⁵ Pa · s, the viscosity at 80 ° C. was 50 Pa · s, and the glass transition temperature was 8 ° C.

  Since the viscosity at 80 ° C. of the epoxy resin composition [A] is low, the primary prepreg is sandwiched between the resin films coated with the epoxy resin composition [A], and heated and pressurized using a press roll to impregnate. In this case, the resin flowed from the end of the resin film and the prepreg processability was slightly deteriorated, but a prepreg having no problem was obtained.

Since the prepreg has a softer resin on the prepreg surface side, the tack is slightly high at 3.0N, and the reworkability is slightly deteriorated (the workability is slightly deteriorated, but it is a level with no problem in use) ). Further, since the resin on the prepreg surface side sinks into the inner layer of the prepreg, the tack life was slightly worse than that of Example 2 for 6 days. The drapeability at room temperature was good. In addition, since there is a soft resin on the prepreg surface side, the amount of resin dropout increases, and the number of cleanings when the prepreg is used continuously for 2000 m by the AFP method is slightly deteriorated to 4 times. There was no level.
(Example 5)
As the epoxy resin composition [A], except that Sumika Excel (registered trademark) 5003P was changed from 14 parts by weight to 18 parts by weight, the same composition as in Example 1 was used. As the epoxy resin composition [B], The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 9 × 10 ⁸ Pa · s, the viscosity at 80 ° C. was 1100 Pa · s, and the glass transition temperature was 12 ° C.

  Since the epoxy resin composition [A] has a high viscosity at 80 ° C., the primary prepreg is sandwiched between the resin films coated with the epoxy resin composition [A], and heated and pressurized using a press roll to impregnate. In this case, the resin remained on the resin film, and the film was breached, and the prepreg processability and quality were slightly deteriorated, but a prepreg having no problem was obtained.

The prepreg had a good tack life of 10 days or more, but because of the presence of a harder resin on the prepreg surface side, the tack was as low as 1.2 N, making it difficult to stick (workability decreased, but use There was no problem with this). The drapeability at room temperature was good. Similarly, when the prepreg was used continuously for 2000 m by the AFP method, the resin powder generated on the surface of the prepreg was dropped and the number of cleanings was slightly deteriorated to 3 times, but the level was not problematic for AFP operation.
(Example 6)
As the epoxy resin composition [A], an epoxy resin composition having the same composition as in Example 1 was used except that ELM434 was changed from 80 parts by weight to 60 parts by weight and jER1055 was changed from 20 parts by weight to 40 parts by weight. As [B], the same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 1 × 10 ⁸ Pa · s, the viscosity at 80 ° C. was 600 Pa · s, and the glass transition temperature was 14 ° C.

The prepreg had a good tack life of 10 days or more, but because of the presence of a harder resin on the prepreg surface side, the tack was slightly low at 1.6 N, and it was slightly difficult to stick (workability was slightly reduced). However, it was a level with no problem in use). The drapeability at room temperature was good. Similarly, when the prepreg was continuously used for 2000 m by the AFP method, the resin powder generated on the surface of the prepreg was dropped, but the number of cleanings was 2 times.
(Example 7)
As the epoxy resin composition [A], an epoxy resin composition having the same composition as in Example 1 was used except that ELM434 was changed from 80 parts by weight to 97 parts by weight and jER1055 was changed from 20 parts by weight to 3 parts by weight. As [B], the same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 5 × 10 ⁵ Pa · s, the viscosity at 80 ° C. was 120 Pa · s, and the glass transition temperature was 7 ° C.

Since the prepreg has a soft resin on the surface side of the prepreg, the tack is slightly high at 2.9 N, and the reworkability is slightly deteriorated (the workability is slightly deteriorated, but it is a level that is not problematic for use) ). Further, since the resin on the prepreg surface side sinks into the inner layer of the prepreg, the tack life was slightly worse than that of Example 1 for 7 days. The drapeability at room temperature was good. In addition, since there is a soft resin on the prepreg surface side, the amount of resin dropout increases, and the number of cleanings when the prepreg is used continuously for 2000 m by the AFP method is slightly deteriorated to 3 times. There was no level.
(Example 8)
The epoxy resin composition [A] had the same composition as in Example 1 except that jER1055 was changed from 20 parts by weight to HM-101 (Dainippon Ink Chemical Co., Ltd .: epoxy equivalent 3200-3900). The same composition as in Example 1 was used as the epoxy resin composition [B]. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 9 × 10 ⁷ Pa · s, the viscosity at 80 ° C. was 500 Pa · s, and the glass transition temperature was 12 ° C.

The prepreg had a tack of 1.8 N and a tack life of 10 days or longer. The drapeability at room temperature was good. Similarly, the number of cleanings when the prepreg was continuously used for 2000 m by the AFP method was as good as 1 time, but the epoxy equivalent increased, so the heat resistance of the composite material decreased.
Example 9
As the epoxy resin composition [A], the same composition as in Example 1 was used except that 20 parts by weight of jER1055 to 20 parts by weight of jER819 was used, and Example 1 was used as the epoxy resin composition [B]. The thing of the same composition was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 8 × 10 ⁵ Pa · s, the viscosity at 80 ° C. was 120 Pa · s, and the glass transition temperature was 8 ° C.

Since the prepreg has a softer resin on the prepreg surface side, the tack is slightly high at 2.7 N, and the reworking workability is slightly deteriorated (the workability is slightly deteriorated, but the use is not a problem level). ). Further, since the resin on the prepreg surface side sinks into the inner layer of the prepreg, the tack life was slightly worse than that of Example 1 for 7 days. The drapeability at room temperature was good. In addition, since there is a soft resin on the prepreg surface side, the amount of resin dropout increases, and the number of cleanings when the prepreg is used continuously for 2000 m by the AFP method is slightly deteriorated to 4 times. There was no level.
(Example 10)
As the epoxy resin composition [A], the same composition as in Example 1 was used, and as the epoxy resin composition [B], Sumika Excel (registered trademark) 5003P was changed from 5 parts by weight to 2 parts by weight. The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [B] was 6 × 10 ² Pa · s.

The prepreg had a good tack of 2.0 N. However, since a soft resin was present on the inner surface of the prepreg and the sinking of the resin was promoted, the tack life was slightly worse than that of Example 1 for 7 days. The drapeability at room temperature was good. Similarly, when the prepreg is used continuously for 2000 m by the AFP method, the resin sinks and the soft resin on the inner surface of the prepreg is likely to be present on the surface. The frequency was as good as 2 times.
(Example 11)
As the epoxy resin composition [A], the same composition as in Example 1 was used, and as the epoxy resin composition [B], Sumika Excel (registered trademark) 5003P was changed from 5 parts by weight to 2 parts by weight. The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [B] was 8 × 10 ⁴ Pa · s.

The prepreg had a tack of 2.0 N and a tack life of 10 days or longer. The draping property at room temperature was hard and slightly difficult to wind because of the presence of a hard resin on the inner surface of the prepreg, but was at a level with no problem. Similarly, the number of cleanings when the prepreg was continuously used for 2000 m by the AFP method was as good as 1 time.
(Comparative Example 1)
As the epoxy resin composition [A], except that Sumika Excel (registered trademark) 5003P was changed from 14 parts by weight to 5 parts by weight, the same composition as in Example 1 was used. As the epoxy resin composition [B], The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] is the viscosity at ^{2 × 10 4 Pa · s,} 80 ℃, 20Pa · s, a glass transition temperature became 7 ° C..

  Since the viscosity at 80 ° C. of the epoxy resin composition [A] is low, the primary prepreg is sandwiched between the resin films coated with the epoxy resin composition [A], and heated and pressurized using a press roll to impregnate. In this case, although the resin flowed from the end of the resin film and the prepreg processability was slightly deteriorated, a prepreg could be produced.

Since the prepreg has a soft resin on the surface side of the prepreg, the tack is as high as 3.6 N, and there is a problem that the reworking operation cannot be performed. In addition, since the resin on the prepreg surface side sinks into the inner layer of the prepreg, the tack life is considerably worse than that of Example 1 for 3 days at room temperature, and after about 4 days, it becomes difficult to attach the prepregs to each other. occured. The drapeability at room temperature was good. In addition, since there is a soft resin on the prepreg surface side, the amount of falling resin increases, and the number of cleanings when the prepreg is similarly used continuously for 2000 m by the AFP method has deteriorated to 10 times, so the operability is greatly reduced. Application by the AFP method was difficult.
(Comparative Example 2)
As the epoxy resin composition [A], ELM434 was changed from 80 parts by weight to 60 parts by weight, jER1055 was changed from 20 parts by weight to jER819 from 40 parts by weight, and SUMIKAEXCEL (registered trademark) 5003P was changed from 14 parts by weight to 5 parts by weight. Other than that, the same composition as in Example 1 was used, and the same composition as in Example 1 was used as the epoxy resin composition [B]. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] was 6 × 10 ⁶ Pa · s, the viscosity at 80 ° C. was 90 Pa · s, and the glass transition temperature was 6 ° C.

  Since the viscosity at 80 ° C. of the epoxy resin composition [A] is low, the primary prepreg is sandwiched between the resin films coated with the epoxy resin composition [A], and heated and pressurized using a press roll to impregnate. In this case, although the resin flowed from the end of the resin film and the prepreg processability was slightly deteriorated, a prepreg could be produced.

The prepreg had a tack of 2.2 N and a tack life of 10 days or longer, both being good. The drapeability at room temperature was good. In addition, since the glass transition temperature of the resin present on the prepreg surface side is low, the resin when the prepreg is used continuously for 2000 m by the AFP method is soft, so the amount of the resin falling off increases and the number of cleanings is 8 times. Since it deteriorated, operativity fell greatly and application by the AFP method was difficult.
(Comparative Example 3)
As an epoxy resin composition [A], ELM434 is changed from 80 parts by weight to 60 parts by weight, jER1055 from 20 parts by weight to jER819 by 20 parts by weight, HM-101 by 20 parts by weight, and SUMIKAEXCEL (registered trademark) 5003P by 14 parts. Except for changing from 13 parts by weight to 13 parts by weight, the same composition as in Example 1 was used. As the epoxy resin composition [B], the same composition as in Example 1 was used. As a result, the viscosity of the epoxy resin composition [A] at 25 ° C. was 2 × 10 ⁸ Pa · s, the viscosity at 80 ° C. was 580 Pa · s, and the glass transition temperature was 17 ° C.

The prepreg had a tack life of 10 days or more, but because of the presence of a harder resin on the prepreg surface side, the tack was as low as 1.4 N, making it difficult to stick (workability was reduced, but use There was no problem level). The drapeability at room temperature was good. Similarly, when the prepreg is used continuously for 2000 m by the AFP method, the resin powder generated on the surface of the prepreg is dropped and the number of cleanings is deteriorated to 6 times. Was difficult.
(Comparative Example 4)
As the epoxy resin composition [A], except that Sumika Excel (registered trademark) 5003P was changed from 14 parts by weight to 20 parts by weight, the same composition as in Example 1 was used. As the epoxy resin composition [B], The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [A] is the viscosity at ^{3 × 10 9 Pa · s,} 80 ℃ is, 1350Pa · s, a glass transition temperature became 13 ° C..

Since the epoxy resin composition [A] was too hard, it could not be used in the resin film manufacturing process in which the resin was uniformly applied to form a resin film.
(Comparative Example 5)
As the epoxy resin composition [A], the same composition as in Example 1 was used, and as the epoxy resin composition [B], Sumika Excel (registered trademark) 5003P was changed from 5 parts by weight to 7 parts by weight. The same composition as in Example 1 was used. As a result, the viscosity at 25 ° C. of the epoxy resin composition [B] was 5 × 10 ⁵ Pa · s.

  The prepreg had a tack of 2.0 N and a tack life of 10 days or longer. The drapeability at room temperature has a problem that a hard resin is present on the inner surface of the prepreg, which makes it hard and difficult to wind, and the prepreg laminated on the surface having a high curvature is peeled off and may be raised. Similarly, the number of cleanings when the prepreg was continuously used for 2000 m by the AFP method was as good as 1 time.

Claims (7)

A prepreg comprising a reinforcing fiber and an epoxy resin composition, having a viscosity at 25 ° C. of 1.0 × 10 ^{5 to} 1.0 × 10 ⁹ Pa · s and a glass transition temperature on both surface sides in the thickness direction of the prepreg Is an epoxy resin composition [A] having a temperature of 7 to 15 ° C. and having a viscosity at 25 ° C. of 5.0 × 10 ^{2 to} 1.0 × 10 ⁵ Pa · s at the center in the thickness direction. A prepreg comprising the composition [B]. The prepreg according to claim 1, wherein the epoxy resin composition [A] has a viscosity at 80 ° C of 100 to 1000 Pa · s. The epoxy resin composition [A] is a bifunctional epoxy resin having an epoxy equivalent of 800 to 3000 g / eq, 5 to 25 parts by weight with respect to 100 parts by weight of all epoxy resins contained in the epoxy resin composition [A]. The prepreg according to claim 1 or 2 comprising. The prepreg according to any one of claims 1 to 3, wherein the reinforcing fibers are arranged in one direction in the longitudinal direction. A slit tape prepreg obtained by cutting the prepreg according to claim 4 into a strip shape parallel to the arrangement direction of the reinforcing fibers. A composite material obtained by laminating and curing the slit tape prepreg according to claim 5 on a mandrel. A primary prepreg is prepared by impregnating the reinforcing fiber with an epoxy resin composition [B] having a viscosity at 25 ° C. of 5.0 × 10 ^{2 to} 1.0 × 10 ⁵ Pa · s, or continuously, or The primary prepreg once wound is unwound, and an epoxy resin composition having a viscosity at 25 ° C. of 1.0 × 10 ^{5 to} 1.0 × 10 ⁹ Pa · s and a glass transition temperature of 7 to 15 ° C. [ A] is impregnated from both sides, and a method for producing a prepreg.