JP3768334B2 - Manufacturing method of unidirectional prepreg - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a unidirectional prepreg (UDPP) with a glass cloth in which a unidirectional reinforcing fiber and a glass scrim cloth are bonded together. More specifically, the present invention relates to a UDPP excellent in adhesion between a unidirectionally aligned reinforcing fiber material and a glass scrim cloth.
[0002]
[Prior art]
Prepreg is widely used as an intermediate material for molding fiber reinforced resin composite materials in which a reinforced fiber material is impregnated with a resin, and the fiber arrangement starts in one direction and varies from woven fabric to nonwoven fabric. The so-called UDPP oriented in the direction is one of the most frequently used prepregs and is usually supplied with a very thin glass cloth (so-called scrim cloth) attached to the surface.
[0003]
The unidirectional prepreg with glass cloth is laminated and molded so as to have a fiber orientation corresponding to the material design of a molded product such as a target pipe, flat plate, or other complex structure. At the time of lamination and molding, if air bubbles are embraced between layers of a unidirectional prepreg with a glass cloth, the mechanical performance of the molded product is remarkably reduced. Therefore, consideration is given to lamination and molding as much as possible without embracing air bubbles. .
[0004]
Such a unidirectional prepreg with a glass cloth is manufactured by superimposing a film-like matrix resin material (resin film) on a row of reinforcing fiber materials arranged in a sheet, and between individual fibers through heating rolls. In addition to impregnation with a matrix resin (hot melt method), after impregnation, a glass cloth is arranged on the surface, and heating and pressurizing are applied (Japanese Patent Publication No. 4-60008, Japanese Patent Publication No. 4-60009).
[0005]
The glass cloth used here is a prepreg state impregnated with a resin or a glass cloth producing machine. However, since the producing machine is prone to misalignment during the process, most of the glass cloth is in a prepreg state to which resin is adhered. Is used.
[0006]
However, the unidirectional prepreg with glass cloth produced by the process of pasting the glass cloth in the prepreg state is poor in passing the matrix resin to the glass cloth once in the prepreg state, and the reinforcing fiber material is impregnated with the matrix resin. In addition, there is a problem that even when the glass cloth is pressed repeatedly, the matrix resin hardly reaches the opposite surface of the glass cloth (the surface not in contact with the reinforcing fiber material). In either case, resin defects occur on the glass cloth surface, particularly on the textured portion of the glass cloth, and in extreme cases, surface irregularities can be confirmed visually. When viewed microscopically, a defective portion of the resin is confirmed on the surface weave (a hole made by warp and weft).
[0007]
In addition, the prepreg having a resin deficient portion on the surface has low adhesiveness (stickiness, tack) between the prepregs at the time of lamination, and it is easy for air bubbles to be embraced at the time of lamination and to move between layers at the time of lamination. The orientation is likely to be disturbed.
[0008]
If the resin impregnation into the glass cloth becomes poor and the adhesion to the reinforcing fiber material becomes weak, the unidirectional prepreg with glass cloth peels off at the interface between the reinforcing fiber material arranged in one direction and the glass cloth during storage. The U-shaped peeled portion can be visually observed in the width direction of the prepreg and the fiber axis direction.
[0009]
For the production of glass cloth prepreg, many methods employing a solvent method are employed. Although this solvent method has an effect of preventing disturbance of the texture of the glass cloth as compared with the hot melt method, it is necessary to remove the solvent after the resin impregnation, and there is a concern about the influence of the residual solvent.
[0010]
There is also known a method in which the aligned reinforcing fiber material row and the resin film are overlapped and the resin is pressed and impregnated between the individual fibers, and the glass cloth generator is overlapped and the resin is pressed and impregnated at the same time.
[0011]
According to such a method, although the concern about the residual solvent is eliminated, the glass fiber swims in the resin when impregnated with the glass cloth because the warp and the weft of the glass cloth are not fixed to each other. The problem arises.
[0012]
[Problems to be solved by the invention]
The unidirectional prepreg with a glass cloth tends to cause resin defects in the glass cloth weave, and bubbles are easily generated in the resin defect on the surface during lamination. In addition, the unidirectional prepreg with a glass cloth wound around the core tube is peeled off at the interface between the reinforcing fiber material arranged in one direction and the glass cloth during storage, and the air accumulated in the peeling part is laminated and laminated. There is a problem that bubbles are formed in the molded product during molding.
[0013]
OBJECT OF THE INVENTION
An object of the present invention is to provide a unidirectional prepreg with a glass cloth which has no resin defect on the surface and has high adhesive strength between the reinforcing fiber material and the glass cloth which are aligned in one direction.
[0014]
[Means for Solving the Problems]
The present invention has the following configuration.
(Claim 1) In manufacturing a unidirectional prepreg with a glass cloth by a hot melt method, a resin film and a glass cloth raw machine are laminated and bonded in advance, and then the sheet-like reinforcing fiber material row is reinforced with the glass cloth surface. A unidirectional prepreg with a glass cloth, which is laminated so that the fiber material row surfaces are adjacent to each other, then supplied to a heating / pressing mechanism to allow the matrix resin to penetrate and impregnate the reinforcing fiber material while passing through the glass cloth layer. Production method.
[0015]
According to the present invention, there is no resin deficient portion on the surface of the unidirectional prepreg with a glass cloth, and the peeling strength is high, so that the reinforcing fiber material and the glass cloth do not peel off during storage or during work. Thus, it is difficult for air to be entrapped at the time of molding, so that a molded article having high strength can be obtained.
[0016]
Normally, unidirectional prepreg with glass cloth covers a wide range of resin content of about 20 to 50% by weight depending on applications, but unidirectional prepreg with glass cloth having a resin content of 30% by weight or less has low resin content. Due to this, the tack tends to be low.
[0017]
In addition, in a matrix resin system in which a solid component such as a thermoplastic resin powder is added to a thermosetting matrix resin, tack tends to be low. Even in such a low-tack unidirectional prepreg with a glass cloth, according to the present invention, there is no peeling of the glass cloth and high adhesion can be obtained.
[0018]
A normal unidirectional prepreg with a glass cloth is a prepreg having a structure in which a sheet-like reinforcing fiber array oriented in one direction and a glass cloth are bonded together, and usually a release paper is arranged on one side. The other surface is covered with a thermoplastic release film such as polyethylene.
[0019]
The unidirectional prepreg with a glass cloth of the present invention has a sheet-like reinforcing fiber material row and a glass cloth firmly bonded to each other, so that they cannot be substantially separated at room temperature such as a working environment. It is firmly adhered to.
[0020]
When observed microscopically, the surface of the glass cloth is covered with the matrix resin, and there is no defective portion of the matrix resin even in the texture of the glass cloth. For this reason, it is considered that the matrix resin spreads in a rivet shape on the front and back of the glass cloth textured portion and has a strong bond strength.
[0021]
As a result of the strong bonding, the glass cloth is cut when it is forced to peel off in the axial direction of the reinforcing fiber material. In order to easily evaluate whether or not the glass cloth is firmly bonded, the glass cloth is carefully peeled off from the end portion of the UDPP cut into a tape shape having a width of about 30 mm. If the glass cloth at the end cannot be peeled off, apply a very small amount of solvent to the end of the unidirectional prepreg with glass cloth, dissolve the matrix resin, and remove the glass cloth with the length necessary to fix it to the jig. Remove from the edge.
[0022]
Next, the end of the glass cloth is wound around a round bar having a diameter of about 8 to 10 mm, and the round bar is gradually rolled so that the force is evenly distributed, and the glass cloth is wound while increasing the amount of peeling. The conventional unidirectional prepreg with a glass cloth can be peeled off, but the unidirectional prepreg with a glass cloth of the present invention cannot be peeled off because the glass cloth is broken.
[0023]
In the present invention, the reinforcing fiber material is a reinforcing fiber group generally used as a reinforcing fiber in a fiber-reinforced resin composite material. Specifically, inorganic fibers, organic fibers, metal fibers, metal-coated fibers or their fibers Made of mixed, inorganic fiber includes carbon fiber, graphite fiber, silicon carbide fiber, alumina fiber, tungsten carbide fiber, boron fiber, glass fiber, etc. Organic fiber includes aramid fiber, high density polyethylene fiber, nylon fiber, polyester Organic fibers such as fibers can be mentioned. The metal fiber is a stainless fiber, and the metal-coated fiber is a fiber in which a metal layer such as nickel or copper is formed on the surface of the inorganic fiber or organic fiber by electrolytic plating or electroless plating. In particular, UDPP using carbon fiber or graphite fiber is preferable, and usually has a basis weight of 50 to 300 g / m 2 ↑.
[0024]
In the present invention, the glass cloth is a so-called scrim cloth used by being bonded to ordinary UDPP, and does not mean a glass fiber fabric used as a reinforcing fiber material. Such a glass cloth (scrim cloth) is a very thin woven fabric having a basis weight (weight per unit area) of 10 to 100 g / m 2 ↑, preferably 20 to 30 g / m 2 ↑ and made of glass fibers.
[0025]
This glass cloth has a function of giving strength in the width direction of the unidirectional prepreg and preventing disorder of the arrangement of the reinforcing fiber materials.
[0026]
In the present invention, the matrix resin is a thermosetting resin usually used as a matrix resin of a fiber-reinforced composite material, and an epoxy resin is particularly preferably used. As the epoxy resin curing agent, any compound having an active group capable of reacting with an epoxy group can be used. Preferably, a compound having an amino group, an acid anhydride group, or an azide group is suitable. Specifically, dicyandiamide, various isomers of diaminodiphenylsulfone, and aminobenzoic acid esters are suitable.
[0027]
As thermosetting resins other than epoxy resins, unsaturated polyester resins, vinyl ester resins and the like can also be used.
[0028]
In the prepreg of the present invention, it is also preferable to mix a thermoplastic resin with the above-mentioned thermosetting resin. Suitable thermoplastic resins are polyacrylates, polyamides, aramids, polyesters, polyphenylene sulfides, polyimides, polyether imides, polysulfones, polyether sulfones, polyether ether ketones. By using these thermoplastic resins in combination, a cured product having high toughness can be obtained.
[0029]
The matrix resin content in the unidirectional prepreg with a glass cloth varies depending on the application and the like, but the resin content (RC) is usually 20 to 50% by weight. Most preferably, it is 20-40 weight%. In order to improve the toughness of the molded product, a thermoplastic resin powder having an amount of 50% by weight or less, particularly 30% by weight or less, and a particle size of 150 μm or less can be added to the matrix resin. In general, the tack tends to be lowered, and as a result, the glass cloth tends to be peeled off. Therefore, the present invention is particularly effective as a countermeasure.
[0030]
It is known that a unidirectional prepreg with a glass cloth can be generally produced as follows. That is, the reinforcing fibers are pulled out from the bobbin and aligned to form a sheet-like reinforcing fiber array.
[0031]
The matrix resin is mixed with a curing agent, a curing accelerator, and other additives to form a film-like resin (so-called B-stage resin film), and is supported on a release paper. The sheet-like reinforcing fiber material row and the resin film are overlapped and supplied to a heating / pressing mechanism such as a heated pressing roller and a hot plate to infiltrate and impregnate the matrix resin between the single fibers of the reinforcing fiber material. The resin film is supplied from one side or both sides of the reinforcing fiber array.
[0032]
In this case, in the present invention, the resin film and the glass cloth are previously overlapped and temporarily bonded, and then overlapped with the sheet-like reinforcing fiber material row. In this case, it is important to overlap the glass cloth surface and the reinforcing fiber material row so as to be adjacent to each other. Next, the reinforcing fiber material is infiltrated and impregnated while being supplied to the heating / pressing mechanism and passing the matrix resin through the glass cloth layer. When the matrix resin is supplied to the reinforcing fiber material in this way, the matrix resin is forced to pass through the glass cloth layer, and the surface of the glass cloth that is not in contact with the reinforcing fiber material serves as a pressing mechanism. Flatness is maintained because of contact. As a result, the reinforcing fiber material layer and the glass cloth are firmly bonded. Here glass cloth used is to use the greige. By using the raw machine, the volatile content of the unidirectional prepreg with glass cloth can be further reduced, and the impregnation property of the matrix resin is also good.
[0033]
As a method of supplying the living machine between the matrix resin and the reinforcing fiber material, a method in which the three members are simultaneously assembled at the tip of the heating / pressing mechanism, a matrix resin is supplied from a slit provided on the back of the living machine, There is a method of impregnating a reinforcing fiber material with a matrix resin in a molten state, but in any case, glass fibers constituting the living machine swim in a highly viscous liquid resin, which causes misalignment.
[0034]
As in the method of the present invention, when a living machine is bonded to a resin film in advance and then overlapped with a sheet-like reinforcing fiber material, the glass cloth is heated and pressed at this point, so that there is almost no fiber misalignment. There is nothing.
[0035]
Moreover, the matrix resin is sandwiched between the glass cloth side surfaces of the release paper interposed between the glass cloth and the pressing mechanism. For this reason, the matrix resin fills the recesses of the weave of the glass cloth, and the sheet-like reinforcing fiber material is so firmly bonded that it cannot be peeled, and the surface of the resin deficient portion is along the surface of the release paper. A unidirectional prepreg with a glass cloth having a smooth surface and almost no surface is obtained.
[0036]
In the unidirectional prepreg with glass cloth obtained by the present invention, the texture of the glass cloth is hardly observed on the surface, and the matrix resin layer is formed on the glass cloth. Moreover, it adheres firmly to such an extent that the glass cloth cannot be peeled off, and the glass cloth is cut when it is forcibly peeled off.
[0037]
【The invention's effect】
The unidirectional prepreg with glass cloth obtained by the present invention sufficiently impregnates the glass cloth with the matrix resin, has good adhesion between the reinforcing fiber material layer and the glass cloth layer, and there is no separation between the two during molding and storage. It gives a one-way prepreg with a high-quality glass cloth without the inclusion of bubbles during molding.
[0038]
Further, there is no resin defect in the weave on the surface of the unidirectional prepreg with glass cloth, and there is no misalignment of the glass cloth.
[0039]
As a result, a molded product formed using the unidirectional prepreg with glass cloth obtained by the present invention has an effect of high composite performance.
[0040]
【Example】
As a matrix resin component, phenol novolac type epoxy resin / bisphenol A type epoxy resin: 70/30 parts by weight, and as a curing agent component, two types of resins having a basis weight of 44 g / m 2 ↑ having a mixing ratio of DICY / DMU: 5/3 parts A film was prepared, and when the resin film was carried on a release paper and wound, the glass cloth was bonded to the opposite surface of the release paper, and was wound up as a resin film with a glass cloth. As the glass cloth, a basis weight of 24.5 g / m2 ↑ was used.
[0041]
At the same time, a resin film having the same resin composition and a basis weight of 35 g / m2 ↑ was separately manufactured. As a reinforcing fiber material, a sheet-like carbon fiber having a basis weight of 150 g / m 2 ↑ in which bundles of carbon fibers (strength 430 kgf / mm 2 ↑, elastic modulus 24 ton / mm 2 ↑) were arranged was prepared.
[0042]
For impregnation, a resin film with glass cloth is placed on one side of the sheet-like carbon fiber so that the glass cloth surface is in contact with the sheet-like carbon fiber, and a resin film without glass cloth is placed on the other side. To the heating and pressing mechanism. At this time, the impregnation was carried out stepwise at a linear pressure of 100 to 120 ° C. and a pressing force of 7 to 8 kg / cm to obtain a uniform unidirectional prepreg with a glass cloth. This unidirectional prepreg with a glass cloth was wound up with a release paper on the surface without the glass cloth and a polyethylene film on the surface of the glass cloth. The resin content (RC) of this unidirectional prepreg with glass cloth was 32% by weight.
[0043]
[Comparative example]
For comparison, both sides of the same sheet-like carbon fiber are supplied with a resin film in which the glass cloth is not adhered among the resin films described above, and the resin is impregnated between the carbon fibers under the same conditions, and then 28 wt. A glass cloth treated with% resin was placed, heated and pressed at 60 ° C. and 2 kg / cm to adhere the glass cloth, and wound up in the same manner. The RC of this unidirectional prepreg with glass cloth was 32% by weight. Both of these unidirectional prepregs with glass cloth were cut into squares with a side of 1 m, and evaluated after standing flat for 7 days in a room controlled at 23 ° C. and RH 65%.
[0044]
As a result, in the unidirectional prepreg with glass cloth obtained by the present invention, no peeling was observed in either the axial direction or the width direction of the reinforcing fiber material. Also, peel off the edge with a small amount of acetone, leave it for a while, volatilize the acetone, cut it into a width of 30 mm, wrap the glass cloth at the edge on a glass rod with a diameter of 8 mm, and gradually peel off the glass cloth as if rolling. As a result of testing the adhesion state by a simple method, it was not possible to peel off 20 mm or more, and a broken portion was observed in the glass cloth, and the entire surface was gradually broken.
[0045]
On the other hand, in the unidirectional prepreg with a glass cloth in which the glass cloth shown in the comparative example is adhered later, the sheet-like carbon fiber and the glass cloth are peeled in a U shape in the axial direction and the width direction of the carbon fiber. It was. In the simple peel test, although there was resistance, the glass cloth was not broken and could be peeled off.
[0046]
In addition, as a result of visual observation of both, the unidirectional prepreg with a glass cloth of the present invention has a smooth surface, and there is no glass cloth irregular reflection, and the carbon fiber black is visually observed as it is, and the texture of the glass cloth is hardly visually observed. There was also no resin defect.
[0047]
On the other hand, the unidirectional prepreg with the post-adhesive glass cloth of the comparative example looked whitish because the texture of the glass cloth was observed. Further, the surface was a glass cloth satin finish.

Claims (1)

In manufacturing a unidirectional prepreg with a glass cloth by the hot melt method, a resin film and a glass cloth raw machine are laminated and bonded in advance, and then a sheet-like reinforcing fiber material row, a glass cloth surface, a reinforcing fiber material row surface, Are laminated so as to be adjacent to each other, and then supplied to a heating / pressing mechanism to allow the matrix resin to penetrate and impregnate the reinforcing fiber material while passing through the glass cloth layer.