JP2009292977A - Prepreg for press molding, and manufacturing method of molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg for press molding that is excellently handleable at ordinary temperatures, suppresses excessive flow of a resin at the time of high-temperature high-pressure molding without excessively lowering its Tg and curing rate, gives a cured resin without turbidity suppressed in defective appearances and defective performances and a molded article having good external appearances and inhibits a defective mold, and a manufacturing method of a molded article using the prepreg for press molding. <P>SOLUTION: The prepreg for press molding comprises a fibrous reinforcing material impregnated with a resin comprising an epoxy resin (X), a phenoxy resin (Y) having a mass-average molecular weight of 50,000-80,000 and an epoxy curing agent (Z), and has a minimum viscosity at 100-150°C of 2-20 Pa s and a viscosity at 30°C of 10,000-100,000 Pa s. The manufacturing method of a molded article comprises using the prepreg for press molding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a prepreg for press molding and a method for producing a molded product using the prepreg for press molding.

  Fiber-reinforced composite materials (hereinafter referred to as “FRP”) are lightweight, high-strength, and high-rigidity, so they are used in a wide range of fields such as fishing and fishing shafts and sports / leisure applications, and automotive and aircraft industrial applications. It has been. For the production of FRP, a method of using a prepreg which is an intermediate material obtained by impregnating a resin into a fiber reinforcing material composed of long fibers such as reinforcing fibers is suitably used. A molded product made of FRP can be obtained by cutting the prepreg into a desired shape and then shaping the prepreg, followed by heat curing in the mold.

However, in general, molding of an epoxy resin prepreg has a long molding time and is difficult to use for a member that requires mass productivity such as an automobile member. On the other hand, high cycle press molding using high temperature and high pressure is known as a molding method frequently used for automobile applications because of its high productivity. Patent Document 2 discloses a method of molding a prepreg by press molding. ing.
In high cycle press molding, high temperature and high pressure conditions of 100 to 150 ° C. and 1 to 15 MPa are usually used. This is because the curing time is shortened by rapid curing and the gas is discharged from the mold due to the proper flow of the prepreg in the mold.

However, when press molding is performed at such a high temperature and high pressure, the resin viscosity decreases due to an increase in the resin temperature of the prepreg, and depending on the structure of the mold, a severe resin outflow is seen from the shear edge portion. Therefore, the appearance of the molded product is insufficient on the surface of the molded product, such as resin dying, poor performance such as fiber meandering, mold operation due to resin inflow into the ejector pins, air valves, etc. in the mold There are cases where molding problems such as defects occur.
On the other hand, as a method for adjusting the flow of the resin in the mold, a method of using a high-viscosity epoxy resin or adding a thermoplastic resin to the epoxy resin is disclosed (for example, Patent Documents 1 and 2). ).
JP 2005-213352 A International Publication No. 2004/48435 Pamphlet

However, when a high-viscosity epoxy resin is used, the resin viscosity at room temperature also increases, so that the handleability of the prepreg at room temperature such as laminating work is significantly reduced. Further, the addition of a general-purpose thermoplastic resin to the epoxy resin has low solubility of the thermoplastic resin in the epoxy resin, and the glass transition temperature (hereinafter referred to as “Tg”) of the resulting epoxy resin composition. Since it causes a decrease, a decrease in the curing rate, etc., it has been difficult to apply to high cycle press molding. In addition, high cycle press molding of epoxy resin prepregs was not common, so the minimum viscosity of the resin in the optimal molding temperature range for high cycle press molding has not been elucidated, and the resin viscosity is controlled to the optimal viscosity range. No use of thermoplastic resin has been found for this purpose.
Furthermore, most thermoplastic resins add turbidity when mixed with epoxy resins. In particular, in the case of an automobile member using carbon fiber, a design product showing a carbon fiber fabric is often required. When the cured resin is turbid, the appearance is poor, and it cannot be used for molded products that require such design properties.
Therefore, a prepreg for press molding that can be applied to high cycle press molding and that can provide a molded product with good appearance without turbidity of the cured resin is desired.

Therefore, the present invention provides a cured resin that has excellent handleability at room temperature and suppresses excessive flow of the resin at the time of high-temperature and high-pressure molding without excessively reducing Tg and the curing rate, thereby suppressing poor appearance and poor performance. An object of the present invention is to provide a prepreg for press molding capable of obtaining a molded product having good appearance without turbidity and capable of suppressing malfunction of a mold.
In addition, the present invention provides a method for producing a molded product having a good appearance with high productivity and no turbidity in the cured resin by using the prepreg for press molding.

  The prepreg for press molding of the present invention comprises 100 parts by mass of epoxy resin (X), 5 to 25 parts by mass of phenoxy resin (Y) having a mass average molecular weight of 50,000 to 80,000, and 5 to 5 of epoxy curing agent (Z). The fiber reinforcing material was impregnated with a resin composition containing 20 parts by mass, having a minimum viscosity of 2 to 20 Pa · s at 100 to 150 ° C. and a viscosity of 10,000 to 100,000 Pa · s at 30 ° C. It is a prepreg.

  Moreover, the manufacturing method of the molded article of the present invention cures the molding material using the prepreg for press molding by heating and pressurizing for 1 to 20 minutes in a mold at 100 to 150 ° C. and 1 to 15 MPa. Is the method.

The press-molding prepreg of the present invention is excellent in handleability at room temperature, and can suppress excessive flow of the resin during high-temperature and high-pressure molding without excessively reducing Tg and the curing rate. Therefore, even with high cycle press molding at high temperature and high pressure, a molded product with good appearance can be obtained in which the cured resin in which defective appearance and poor performance are suppressed has no turbidity. Moreover, the defect of a metal mold | die can also be suppressed.
Further, according to the production method of the present invention, a molded product having a good appearance can be obtained with high productivity and no turbidity in the cured resin by curing at a high temperature and a high pressure.

<Press forming prepreg>
The prepreg for press molding of the present invention is a prepreg obtained by impregnating a fiber reinforcing material with an epoxy resin composition containing an epoxy resin (X), a phenoxy resin (Y), and an epoxy curing agent (Z). The prepreg for press molding of the present invention can be suitably used for high cycle press molding that is cured in a short time under high temperature and high pressure to obtain a molded product having good appearance without turbidity of the cured resin.

[Epoxy resin composition]
(Epoxy resin (X))
Examples of the epoxy resin (X) include bifunctional epoxy resins and trifunctional or higher polyfunctional epoxy resins.
Examples of the bifunctional epoxy resin include bisphenol A type epoxy resin (for example, Epicoat 828 (jER828) manufactured by Japan Epoxy Resin Co., Ltd.), bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, Examples thereof include naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, fluorene type epoxy resins, and epoxy resins obtained by modifying these.
Examples of the trifunctional or higher polyfunctional epoxy resin include a phenol novolac type epoxy resin, a cresol type epoxy resin, a glycidylamine type epoxy resin such as tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, tetraglycidylamine, and tetrakis (glycidyl). Examples thereof include glycidyl ether type epoxy resins such as oxyphenyl) ethane and tris (glycidyloxymethane), epoxy resins obtained by modifying these, and brominated epoxy resins obtained by brominating these epoxy resins.
These epoxy resins may be used alone or in combination of two or more.

  The epoxy resin (X) is preferably an epoxy resin having a bisphenol skeleton from the viewpoint of solubility with the phenoxy resin.

(Phenoxy resin (Y))
The phenoxy resin (Y) is a resin that plays a role of adjusting the fluidity of the epoxy resin composition.
The phenoxy resin (Y) is a resin having a mass average molecular weight of 50,000 to 80,000.
When the mass average molecular weight of the phenoxy resin (Y) exceeds 80,000, it becomes difficult to dissolve in the epoxy resin, and the viscosity of the epoxy resin composition becomes too high even with a very small amount of blending, and the viscosity of the epoxy resin composition is reduced. It becomes difficult to obtain an appropriate viscosity range defined by the present invention. Further, when the mass average molecular weight is less than 50,000, the viscosity of the epoxy resin composition is too low, and the viscosity of the epoxy resin composition is set to an appropriate viscosity range defined in the present invention with an appropriate blending amount. It becomes difficult.

  The phenoxy resin is a linear high molecular weight polyhydroxy polyether synthesized from bisphenol A, bisphenol F, bisphenol F or the like, and is used as a tough and flexible thermoplastic resin. Specific examples of the phenoxy resin (Y) used in the present invention include, for example, YP-50 (mass average molecular weight 60,000-80,000), YP-50S (mass average molecular weight 50,000-70, manufactured by Tohto Kasei). 000), YP-70 (mass average molecular weight 50,000-70,000) and the like. Especially, it is preferable that it is YP-50S which can adjust the viscosity of an epoxy resin composition to the appropriate viscosity range which this invention prescribes | regulates by small addition, and is excellent also in the solubility to an epoxy resin.

The usage-amount of the phenoxy resin (Y) in an epoxy resin composition is 5-25 mass parts with respect to 100 mass parts of epoxy resins, and it is preferable that it is 7-17 mass parts.
By setting the amount of the phenoxy resin (Y) to 5 parts by mass or more, it is possible to suppress the outflow from the mold due to excessive flow of the epoxy resin composition at the time of high-temperature and high-pressure molding, and there is no surface defect such as resin withering. A molded product can be obtained. Moreover, by making the usage-amount of phenoxy resin (Y) into 25 mass parts or less, melt | dissolution to an epoxy resin is easy, and the fall of Tg of an epoxy resin composition and the fall of a cure rate can be suppressed. Moreover, the cured resin is free from turbidity and a molded product having a good appearance can be obtained.

(Epoxy curing agent)
The epoxy curing agent (Z) plays a role of keeping the crosslinking density and curing rate of the epoxy resin composition within an appropriate range.
As an epoxy hardening | curing agent (Z), what is normally used as a hardening | curing agent for epoxy resins can be used. The epoxy curing agent (Z) is preferably dicyandiamide (DICY), which is an amide-based curing agent, from the viewpoint of excellent curability and physical properties after curing.
Specific examples include jER Cure DICY15 manufactured by Japan Epoxy Resin Co., Ltd.

Moreover, when using DICY, it is more preferable to use together with a urea type hardening | curing agent. Since DICY is not very soluble in epoxy resin, it needs to be heated to a high temperature of 160 ° C. or higher in order to sufficiently dissolve it, but the dissolution temperature can be lowered by using it together with a urea-based curing agent. .
Examples of urea-based curing agents include phenyldimethylurea (PDMU) and toluenebisdimethylurea (TBDMU).

The usage-amount of the epoxy hardening | curing agent (Z) in an epoxy resin composition is 5-20 mass parts with respect to 100 mass parts of epoxy resins. If the usage-amount of an epoxy hardening | curing agent (Z) is 5 mass parts or more, a crosslinking density will become enough and sufficient hardening rate will be obtained. When the epoxy curing agent (Z) is 20 parts by mass or less, it is possible to suppress problems such as a decrease in mechanical properties of the cured resin and turbidity of the cured resin due to the excessive presence of the curing agent.
As the epoxy curing agent (Z), when DICY and urea curing agent (PDMU, TBDMU, etc.) are used in combination, their use amount is 2 to 15 parts by mass with respect to 100 parts by mass of the epoxy resin (X). The urea curing agent is preferably 1 to 10 parts by mass (however, the total amount of DICY and urea curing agent is 5 to 20 parts by mass).

(Other ingredients)
In addition, the epoxy resin composition of the present invention does not adversely affect the minimum viscosity at 100 to 150 ° C., the viscosity at 30 ° C., the Tg, the curing rate, the turbidity of the cured resin of the resulting molded product, etc. Within the range, other components other than the epoxy resin (X), the phenoxy resin (Y), and the epoxy curing agent (Z) may be contained.
Examples of other components include 3,3′-diaminodiphenylsulfone, diaminodiphenylsulfone (DDS) such as 4,4′-diaminodiphenylsulfone, and modified products thereof. Specific examples include Seika Cure S manufactured by Wakayama Seika Co., Ltd.
By using DDS, not only excellent mechanical strength and heat resistance can be obtained, but also the viscosity of the epoxy resin used for the adjustment of the resin composition can be adjusted, and the curing can be accelerated.

  Other components include inorganic fine particles such as finely divided silica, pigments, elastomers, flame retardants such as aluminum hydroxide, bromine compounds or phosphorus compounds, defoaming agents, handling properties and flexibility. Examples thereof include a polyvinyl acetal resin to be improved, an imidazole derivative, a metal complex salt, or a tertiary amine compound that serves as a catalyst for a curing reaction.

The epoxy resin composition of the present invention is a composition containing 100 parts by mass of the epoxy resin (X), 5 to 25 parts by mass of the phenoxy resin (Y), and 5 to 20 parts by mass of the epoxy curing agent (Z). is there.
The epoxy resin composition of the present invention has a minimum viscosity of 2 to 20 Pa · s at 100 to 150 ° C. The minimum viscosity at 100 to 150 ° C. means the minimum value of viscosity (temperature increase viscosity) within a temperature range from 100 ° C. to 150 ° C. when the epoxy resin composition is heated. The temperature rise viscosity can be measured with a frequency of 1 Hz and a parallel plate (25 mmφ, gap 0.5 mm) using, for example, DSR-200 manufactured by Rheometric Co., Ltd. or an apparatus having equivalent performance.
By setting the minimum viscosity at 100 to 150 ° C. to 2 Pa · s or more, the resin (epoxy resin composition) exhibits appropriate fluidity, and suppresses excessive flow in the mold during molding at high temperature and high pressure. In addition, a high-quality molded product can be obtained, and it is possible to prevent the resin from flowing out from the shear edge portion of the mold, resulting in a defective appearance or a fiber meandering. Further, it is possible to prevent the mold from malfunctioning due to the resin flowing into the ejector pin, the air valve or the like in the mold. In addition, by setting the minimum viscosity at 100 to 150 ° C. to 20 Pa · s or less, the viscosity at the time of molding is too high, the resin flow becomes insufficient, and it becomes difficult for gas to escape from the molded product, resulting in a defect. Or remaining unfilled parts in the molded product can be prevented.
The minimum viscosity at 100 to 150 ° C. of the epoxy resin composition of the present invention is preferably 2 to 20 Pa · s, and more preferably 3 to 18 Pa · s.

The epoxy resin composition of the present invention has a viscosity at 30 ° C. of 10,000 to 100,000 Pa · s. In prepreg press molding, the prepreg is often cut into a predetermined shape before molding and laminated to form a preform. However, if the viscosity at 30 ° C. is 10,000 Pa · s or more, it is possible to perform lamination at room temperature. The prepreg is less sticky and good workability is obtained. Further, if the viscosity at 30 ° C. is 100,000 Pa · s or less, the prepreg maintains sufficient flexibility and is necessary for laminating the prepreg in accordance with the shape of the mold in the preform creation operation. The shape can be maintained.
The viscosity can be measured at a frequency of 1 Hz and a parallel plate (25 mmφ, gap 0.5 mm) using, for example, a DSR-200 manufactured by Rheometric Co., Ltd. or a device having equivalent performance, similarly to the temperature rising viscosity. .
The minimum viscosity at 100 to 150 ° C. and the viscosity at 30 ° C. of the epoxy resin composition should be adjusted according to the type of epoxy resin (X), the type of phenoxy resin (Y) and the epoxy curing agent (Z) and the amount used. Can do.

Moreover, it is preferable that the hardened | cured material Tg of the epoxy resin composition of this invention is -30 degreeC or more of hardening temperature. If the cured product Tg of the epoxy resin composition is at a curing temperature of −30 ° C. or higher, it is easy to remove from the mold (mold) and deformation after demolding hardly occurs.
Moreover, it is preferable that the epoxy resin composition of this invention hardens | cures in 1 to 20 minutes, when it heat-presses on the conditions of 100-150 degreeC of hardening temperature and 1-15 MPa of molding pressures.

(Method for producing epoxy resin composition)
As a manufacturing method of the epoxy resin composition in the present invention, for example, the above-mentioned epoxy resin (X), phenoxy resin (Y), epoxy curing agent (Z), and other components to be added as necessary are added in appropriate amounts. And mixing them.
Moreover, when using DDS as another component, after preliminarily reacting DDS and epoxy resin (X) to predetermined viscosity, it can also mix with a phenoxy resin (Y) and an epoxy hardener (Z). . Examples of the predetermined viscosity include a viscosity at 90 ° C. of 4 to 13 Pa · s.
When the epoxy curing agent (Z) is a solid, it may be mixed with the liquid epoxy resin (X) in advance and then mixed with the remaining components.

  Moreover, it is preferable that it is 50-65 degreeC, and, as for the mixing temperature at the time of mixing the component of these main ingredients and hardening | curing agents, it is more preferable that it is 55-60 degreeC. When the mixing temperature is 50 ° C. or higher, mixing of the components becomes easy. Moreover, if mixing temperature is 65 degrees C or less, it will be easy to suppress that an epoxy resin composition raise | generates hardening reaction.

[Fiber reinforcement]
As the fiber reinforcing material in the present invention, fibers usually used as a reinforcing material for FRP can be used. Examples thereof include carbon fiber, glass fiber, aramid fiber, polyester fiber, mineral fiber (for example, basalt fiber) and the like. It is done. Among these, carbon fiber is preferable because it is lightweight, has high strength, has a high elastic modulus, and is excellent in heat resistance and chemical resistance.
Examples of the carbon fiber include pitch type, polyacrylonitrile (PAN type), rayon type, etc., and any carbon fiber may be used. From the viewpoint of carbon fiber productivity, the use of PAN type carbon fiber is acceptable. Is more preferable.
Examples of the form of the fiber reinforcing material include forms such as a milled fiber form, a chopped fiber form, a continuous fiber, and various woven fabrics.

[Method for producing prepreg for press molding]
The prepreg for press molding of the present invention is a prepreg in which these fiber reinforcing materials are impregnated with the above-described epoxy resin composition.
The press molding prepreg can be produced by any method as long as the fiber reinforcing material can be impregnated with the epoxy resin composition. For example, the epoxy resin composition thinly coated on the release paper and the fiber reinforcing material in various forms And a prepreg method in which impregnation is carried out.

  Since the prepreg for press molding of the present invention described above controls the viscosity at 30 ° C. and the minimum viscosity at 100 to 150 ° C. of the epoxy resin composition, it is excellent in handleability at room temperature and is a mold at the time of molding. The excessive flow of the resin inside is suppressed. Moreover, since an epoxy resin composition is the said composition, the fall of Tg of an epoxy resin composition and the fall of a cure rate can be suppressed. In particular, since the phenoxy resin (Y) is used among the thermoplastic resins, the cured resin in the molded article does not become turbid. Therefore, by high cycle press molding by curing for a short time under high temperature and high pressure, the cured resin has no turbidity and a high-quality molded product having a good appearance can be obtained with high productivity.

<Method for producing molded product>
The method for producing a molded product according to the present invention is a method for obtaining a molded product by curing and molding a molding material using the above-described prepreg for press molding with a mold at a high temperature and a high pressure. In particular, the production method of the present invention can be suitably used for high cycle press molding of a molded product (FRP) having good appearance and no turbidity in the effect resin.

[Mold]
The mold in the production method of the present invention may be a mold that can cure the molding material under high temperature and high pressure, and has a structure that can keep the inside of the mold airtight when the mold is closed. It is preferable to use a metal mold. Here, airtight means that an epoxy resin composition constituting the molding material is substantially leaked from the mold even when a sufficient amount of the molding material is filled in the mold and pressed. Say nothing.
Examples of molds that keep the interior airtight include molds that employ a shear edge structure (see Fig. 1) or a rubber seal structure where the upper and lower molds (male and female molds) come into contact when the mold is tightened. It is done. Further, a mold using any known structure may be used as long as the inside of the mold is kept airtight.

FIG. 1 is a sectional view showing an embodiment of a mold that can be used in the manufacturing method of the present invention.
The mold 1 has an upper mold 2 (female mold) and a lower mold 3 (male mold). The upper die 2 is provided with a female shear edge portion 4, and the lower die 3 is provided with a male shear edge portion 5. The inside of the mold 1 is kept airtight when the upper mold 2 and the lower mold 3 are closed by the shear edge structure (the female shear edge portion 4 and the male shear edge portion 5).

  In addition, air remaining inside the mold 1 when the mold 1 is closed may cause pinholes on the surface of the molded product (FRP) and voids inside the molded product. When a mold having a mechanism is used and the interior of the mold 1 is filled with the molding material, the air remaining in the mold 1 is effectively degassed by deaeration using the deaeration mechanism. Is possible. As a deaeration mechanism, for example, a mechanism that opens and closes the lower mold 3 of the mold 1 (for example, a hole described in International Publication No. 2004/048435 pamphlet) to release air to the outside of the mold 1 And a mechanism for further reducing the pressure by providing a pump in the hole. In this case, the deaeration is performed by opening a hole until the inside of the mold 1 is filled with the molding material and closing it when pressurized.

  Furthermore, a mechanism for removing the molded product such as an ejector pin and an air valve can be attached to the mold 1 in order to facilitate removal of the molded product after the molding of the molded product is completed. This mechanism is suitable for mass production because the molded product can be easily taken out without waiting for cooling of the mold 1. The mechanism for releasing the mold may be any conventionally known mechanism other than the ejector pin and the air valve.

[Production method]
Hereinafter, as an example of an embodiment of a method for producing a molded article of the present invention, a method using the mold 1 illustrated in FIG. 1 will be described.
First, after the mold 1 is adjusted to a temperature equal to or higher than the curing temperature of the epoxy resin composition, a molding material 6 (one obtained by cutting a prepreg for press molding and laminating it) is disposed on the lower mold 3 (FIG. 1). (A)). Next, the upper mold 2 and the lower mold 3 are closed and pressed to form (FIG. 1B). The resin (epoxy resin composition) hardly flows out of the mold 1, and the molding material 6 is pressurized to fill all the interior of the mold 1.

  In addition, from the viewpoint of suppressing the flow of the resin in the mold 1 and suppressing the meandering of the fiber of the molded product, the surface area on one side of the molding material 6 (molding material 6 in FIG. 1A) before entering the mold 1 is reduced. It is preferable that the surface area of the inside of the mold that comes into contact with one side of the molding material 6 when the mold 1 is closed (the same surface area as the one side surface of the obtained molded product) is kept close. Here, the single-sided surface area of the molding material is the surface area of one of the two surfaces constituting the molded product (the surface in contact with the upper mold 2 and the lower mold 3), and the same can be said for both surfaces. .

Specifically, the ratio S ₁ / S ₂ between the single-sided surface area S ₁ of the molding material 6 and the surface area S ₂ of the contact surface with the one side of the molding material inside the mold when the mold 1 is closed is 0. .8 to 1 is preferable.
If S ₁ / S ₂ is 0.8 or more, the flow of the resin inside the mold 1 can be easily suppressed, so that fiber meandering is less likely to occur. Further, if S ₁ / S ₂ is 1 or less, it is possible to prevent the peripheral portion of the molding material from protruding from the mold 1 and close the mold 1 so that an obstacle or a shortage of the molding material in the molded product occurs. Cheap. Moreover, it is easy to prevent the fiber orientation from being disturbed by the molding material being folded in the mold 1.

In particular, when a high-quality molded product is obtained, the volume and height of the molding material 6 are also preferably close to the obtained molded product (the shape inside the mold when the mold is tightened). . Specifically, it may be 100 to 120% of the volume of the molded product that can obtain the volume of the molding material 6 put into the mold, and 100 to 150% of the thickness of the molded product that can obtain the thickness of the molding material 6. preferable.
When the volume of the molding material 6 put into the mold 1 is less than 100% of the volume of the molded product to be obtained, it is difficult to apply sufficient pressure to the molding material 6. On the other hand, when the volume of the molding material 6 put into the mold 1 exceeds 120% of the volume of the molded product to be obtained, the molding material 6 is removed before the mold 1 is hermetically sealed when the mold 1 is closed. It becomes easy to leak.
Moreover, when the thickness of the molding material 6 is less than 100% of the thickness of the molded product to be obtained and when it exceeds 150%, it is difficult to pressurize the entire surface of the molding material 6 evenly. Here, the thickness of the molding material 6 and the thickness of the obtained molded product are thicknesses obtained by averaging the thickness of the molding material and the obtained molded product, respectively.

  The curing temperature is 100 to 150 ° C. When the curing temperature is 100 ° C. or higher, a curing reaction can be sufficiently caused, and a molded product can be obtained with high productivity. Further, if the molding temperature is 150 ° C. or less, excessive resin flow in the mold 1 due to the resin viscosity becoming too low can be suppressed, and resin outflow and fiber meandering from the mold 1 can be suppressed. Therefore, a high-quality molded product can be obtained.

Moreover, the pressure at the time of shaping | molding is 1-15 Mpa. If the pressure is 1 MPa or more, an appropriate flow of the resin can be obtained, and appearance defects and voids due to poor gas escape can be prevented, and the molding material firmly adheres to the mold, so good appearance quality Can be obtained. In addition, when the pressure is 15 MPa or less, it is possible to suppress the occurrence of problems such as an appearance defect caused by flowing the resin more than necessary and deformation caused by applying an excessive load on the mold.
Moreover, the hardening time in the manufacturing method of this invention is 1 to 20 minutes. As a result, it is possible to produce a molded product of excellent quality with high productivity.

  Since the molded product obtained by the production method of the present invention has no turbidity in the cured resin and has a good appearance, it can be suitably used for applications such as a molded product having a cross design that shows the woven pattern of the carbon fiber cloth as it is.

According to the manufacturing method of this invention demonstrated above, it can suppress that a defect arises in a metal mold | die at the time of shaping | molding. In addition, it is possible to obtain a high-quality molded product with high productivity that suppresses poor appearance and poor performance and does not cause the cured resin to become cloudy.
In addition, the manufacturing method of this invention is not limited to the method of using the metal mold 1 illustrated in FIG. A method using a mold other than the mold 1 may be used as long as the mold can be cured in a short time under the aforementioned high temperature and pressure.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
<Epoxy resin composition>
[Various measurement methods]
In this example, the minimum viscosity at 100 to 150 ° C., the viscosity at 30 ° C., the cured product Tg of the epoxy resin composition, and the 90% cure time using a curast meter were measured by the following methods.
(Minimum viscosity at 100 to 150 ° C. and viscosity at 30 ° C.)
Apparatus: DSR-200 manufactured by Rheometrics Co., Ltd.
Measurement mode: Parallel plate (25mmφ, gap 0.5mm)
Frequency: 1Hz
Temperature setting: The viscosity was measured while increasing the temperature from 30 ° C. to 120 ° C. at 2 ° C./min.
About the minimum viscosity, since the minimum viscosity was confirmed in the vicinity of 100 ° C and the viscosity increased thereafter, the measurement was performed up to 120 ° C.

(Hardened product Tg of epoxy resin composition)
The cured product Tg of the epoxy resin composition was measured according to ASTM D4065 using an ARS-DMA dynamic viscoelasticity measuring apparatus manufactured by TA Instrument, and the storage elastic modulus (G ′) with respect to temperature as shown in FIG. The logarithmic value was plotted, and the temperature at the intersection of each tangent line of the glass elastic region and the transition region of the obtained G ′ curve was defined as the glass transition temperature (Tg).

[material]
The raw material used for manufacture of an epoxy resin composition is shown below.
(Epoxy resin (X))
EP828: Bisphenol A type epoxy resin (trade name: jER828, manufactured by Japan Epoxy Resin Co., Ltd.)
(Phenoxy resin (Y))
YP50S: Phenoxy resin (trade name phenototo YP50S, manufactured by Tohto Kasei Co., Ltd., mass average molecular weight 50,000 to 70,000)
(Epoxy curing agent (Z))
DICY: Dicyandiamide (trade name: jER Cure DICY15, manufactured by Japan Epoxy Resin Co., Ltd.)
PDMU: Phenyldimethylurea (trade name: Omicure 94, manufactured by PTI Japan Co., Ltd.)
(Other ingredients)
DDS: 4,4′-diaminodiphenyl sulfone (trade name: Seika Cure S, manufactured by Wakayama Seika Co., Ltd.)
PES: Polyethersulfone (trade name: E2020P, mass average molecular weight 32,000)

[Production Example 1]
EP828 and DDS are mixed at EP828 / DDS = 100/9 (unit: parts by mass) and heated at 150 ° C. to perform a pre-reaction so that the viscosity at 90 ° C. becomes 9 Pa · s. (I) was obtained.
Also, DICY and PDMU are added to EP828, mixed, and uniformly dispersed using a three-roll mill, and a paste of EP828 / DICY / PDMU = 11.38 / 6.07 / 4.55 (unit: parts by mass) A resin composition (II) was obtained.
Furthermore, it mixed in the ratio of EP828 / YP50S = 2/1 (unit: mass part), and it was made to melt | dissolve uniformly at 160 degreeC, and resin composition (III) was obtained.
Subsequently, 71.61 parts by mass of the resin composition (I), 19.71 parts by mass of the resin composition (II), and 27.26 parts by mass of the resin composition (III) were mixed at 55 ° C. to obtain an epoxy resin composition. (A) was obtained.
The mass ratio of the phenoxy resin (Y) in the obtained epoxy resin composition (A) is the total epoxy resin (resin composition (I) + resin composition (II) and (III) in the epoxy resin composition (A). ) Was 9.1 parts by mass with respect to 100 parts by mass of epoxy resin (X)). Moreover, the mass ratio of the epoxy curing agent (Z) in the epoxy resin composition (A) was 9.49 parts by mass with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition (A).
Moreover, Tg of the hardened | cured material which hardened the obtained epoxy resin composition (A) in 140 degreeC and 10 minutes was 131 degreeC.

[Production Example 2]
An epoxy resin was prepared by mixing 56.42 parts by mass of resin composition (I), 19.71 parts by mass of resin composition (II), and 50.05 parts by mass of resin composition (III) in the same manner as in Example 1. A composition (B) was obtained. The mass ratio of the phenoxy resin (Y) in the obtained epoxy resin composition (B) was 16.7 parts by mass with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition (B). Moreover, the mass ratio of the epoxy curing agent (Z) in the epoxy resin composition (B) was 9.49 parts by mass with respect to 100 parts by mass of the epoxy resin (X).
Moreover, Tg of the hardened | cured material which hardened the obtained epoxy resin composition (B) in 140 degreeC and 10 minutes was 131 degreeC.

[Production Example 3]
An epoxy resin was prepared by mixing 43.69 parts by mass of the resin composition (I), 19.71 parts by mass of the resin composition (II), and 69.13 parts by mass of the resin composition (III) in the same manner as in Example 1. A composition (C) was obtained.
Moreover, the mass ratio of the phenoxy resin (Y) in the obtained epoxy resin composition (C) was 23 mass parts with respect to 100 mass parts of all the epoxy resins in an epoxy resin composition (C). Moreover, the mass ratio of the epoxy curing agent (Z) in the epoxy resin composition (C) was 9.49 parts by mass with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition (C).
Tg of the cured product obtained by curing the obtained epoxy resin composition (C) at 140 ° C. for 10 minutes was 130 ° C.

[Production Example 4]
An epoxy resin composition (D) was obtained in the same manner as in Example 1 except that the phenoxy resin (Y) was not used.
Moreover, Tg of the obtained epoxy resin composition (D) was 139 degreeC.

[Production Example 5]
Polyethersulfone (PES) resin was blended with EP828 at a ratio of 7/3 (parts by mass) and uniformly dissolved at 180 ° C. to obtain a resin composition (IV). An epoxy resin was prepared by mixing 78.10 parts by mass of the resin composition (I), 19.75 parts by mass of the resin composition (II), and 16.7 parts by mass of the resin composition (IV) in the same manner as in Example 1. A composition (E) was obtained. Moreover, the mass ratio of the PES resin in the obtained epoxy resin composition (E) was 5 mass parts with respect to 100 mass parts of all the epoxy resins in an epoxy resin composition (E). Moreover, the mass ratio of the epoxy curing agent (Z) in the epoxy resin composition (E) was 9.54 parts by mass with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition (E).

[Production Example 6]
An epoxy resin was prepared by mixing 66.46 parts by mass of the resin composition (I), 19.75 parts by mass of the resin composition (II), and 33.32 parts by mass of the resin composition (IV) in the same manner as in Example 1. A composition (F) was obtained. The mass ratio of the PES resin in the obtained epoxy resin composition (F) was 10 parts by mass with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition (F). Moreover, the mass ratio of the epoxy curing agent (Z) in the epoxy resin composition (F) was 9.54 parts by mass with respect to 100 parts by mass of the total epoxy resin in the epoxy resin composition (F).
About the epoxy resin composition obtained by manufacture example 1-6, the result of having measured the minimum viscosity in 100-150 degreeC and the viscosity in 30 degreeC is shown in FIG.1 and FIG.2.

As shown in FIGS. 1 and 2, Production Examples 1 to 3 using the phenoxy resin (Y) have a viscosity at 30 ° C. in the range of 10,000 to 100,000 Pa · s, and 100 ° C. to 150 ° C. The minimum viscosity was in the range of 2 to 20 Pa · s.
On the other hand, in Production Example 4 in which no phenoxy resin (Y) was used, the viscosity at 30 ° C. was in the range of 10,000 to 100,000 Pa · s, but the minimum viscosity at 100 ° C. to 150 ° C. was less than 2 Pa · s. Met.
In addition, in Production Examples 5 and 6 using the PES resin, the viscosity at 30 ° C. is in the range of 10,000 to 100,000 Pa · s, as in Production Examples 1 to 3 using the phenoxy resin (Y). And the minimum viscosity in 100 to 150 degreeC was in the range of 2-20 Pa.s.

<Manufacture of molded products>
[Example 1]
The epoxy resin composition (A) obtained in Production Example 1 was uniformly coated on a release paper with a basis weight of 133 g / m ² using a simple roll coater to form a resin layer. Next, 3K plain weave carbon fiber cloth TR3110M manufactured by Mitsubishi Rayon Co., Ltd. is attached to the resin layer, and then heated and pressed with a roller at 100 ° C. and a linear pressure of 0.1 MPa to impregnate the carbon fiber with the epoxy resin composition. A press molding prepreg having a fiber basis weight of 200 g / m ² and a resin content of 40% by mass was produced.
Next, the prepreg for press molding was cut into a length of 298 mm × 298 mm, and 10 sheets (thickness 2.2 mm, layer volume 195.4 cm ³ , single-sided surface area) so that the fiber orientation directions were alternately 0 ° and 90 °. S ₁ (surface area of the lower surface) 888.0 cm ² ) A laminated preform was prepared.

As the mold, the mold 1 illustrated in FIG. 1 was used. The surface area S ₂ of the surface that contacts the preform of the lower mold 3 of the mold 1 (excluding the surface that contacts the thickness portion of the preform) was 900.0 cm ² . _{S 1} / S ₂ was 888.0 / 900.0 = 0.987.
The upper mold 2 and the lower mold 3 of the mold 1 are heated to 140 ° C. in advance, the preform is placed on the lower mold 3, the upper mold 2 is immediately lowered, the mold 1 is closed, and a pressure of 10 MPa is applied. And then cured by heating and pressing for 10 minutes, and after curing, the product was taken out from the mold 1 to obtain a molded product.

[Examples 2-3]
A molded product was obtained in the same manner as in Example 1 except that the epoxy resin compositions (B) and (C) obtained in Production Example 2 (Example 2) or 3 (Example 3) were used.

[Comparative Examples 1-3]
Except for using the epoxy resin compositions (D), (E), and (F) obtained in Production Example 4 (Comparative Example 1), Production Example 5 (Comparative Example 2), or Production Example 6 (Comparative Example 3). Obtained a molded product in the same manner as in Example 1.

[Evaluation methods]
The evaluation in Examples 1 and 2 and Comparative Example 1 was performed by evaluating the appearance of the molded product (resin withering, turbidity of the cured resin in the molded product) and the amount of resin outflow from the mold shear edge.
(Resin withering of molded products)
○: None at all △: 1 to 2 places ×: Many occurrences (the turbidity of the cured resin in the molded product)
○: No turbidity, good appearance △: Some turbidity ×: Turbidity, poor appearance (resin outflow from mold shear edge (%))
W1: Preform weight before molding (g)
W2: Weight of molded product after molding (after deburring) (g)
Resin flow rate (%) = (W2−W1) / W1 × 100
The evaluation results for Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

  As shown in Table 1, in Examples 1 to 3 using the epoxy resin composition of the present invention, the resin outflow from the mold shear edge was kept low, and no resin withering occurred. Moreover, there was no turbidity of the cured resin, and a molded product having a good appearance was obtained.

On the other hand, in Comparative Example 1 in which the phenoxy resin (Y) was not used, the amount of the resin flowing out from the mold shear edge was large, many resin withering was observed, and the appearance was inferior to the examples.
Further, in Comparative Examples 2 and 3 using PES resin, the resin outflow from the mold shear edge was suppressed to a low level, and no resin withering occurred, but the cured resin was turbid, compared to the Examples. The appearance was inferior.

  Since the prepreg for press molding of the present invention and the method for producing a molded product using the prepreg for press molding can produce a molded product of excellent quality with good appearance without turbidity in the cured resin, the cured resin The FRP can be suitably used for production by high cycle press molding of FRP having good appearance and no turbidity.

It is sectional drawing which showed one embodiment of the metal mold | die which can be used for manufacture of the molded article of this invention. (A) The mold is open. (B) The mold is closed. It is the figure which showed the viscosity in 30-120 degreeC of the epoxy resin composition of manufacture example 1-6. It is the figure which showed the minimum viscosity in 100-150 degreeC of the epoxy resin composition of manufacture example 1-6. It is the graph which plotted the logarithm value of the storage elastic modulus (G ') with respect to the temperature of hardened | cured material, and is used when calculating | requiring the glass transition temperature of this hardened | cured material from the intersection of the tangent of the graph in a glass state, and the tangent in a transition region It is a graph to do.

Explanation of symbols

  1 Mold 2 Upper mold 3 Lower mold 6 Molding material

Claims (2)

  Including 100 parts by mass of epoxy resin (X), 5 to 25 parts by mass of phenoxy resin (Y) having a mass average molecular weight of 50,000 to 80,000, and 5 to 20 parts by mass of epoxy curing agent (Z), A prepreg for press molding in which a fiber reinforcement is impregnated with a resin composition having a minimum viscosity of 2 to 20 Pa · s at 150 ° C. and a viscosity of 10,000 to 100,000 Pa · s at 30 ° C.   A method for producing a molded product, wherein the molding material using the prepreg for press molding according to claim 1 is cured by heating and pressurizing in a mold for 1 to 20 minutes under conditions of 100 to 150 ° C and 1 to 15 MPa.

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