JPH06102732B2 - Method for preparing matrix resin for prepreg - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for preparing a matrix resin of a prepreg used for molding a fiber reinforced composite material such as a fiber reinforced plastic.

[Prior Art] A prepreg used for molding a fiber-reinforced plastic structure is composed of a reinforcing fiber and a matrix resin which is transferred and impregnated with the reinforcing fiber. This matrix resin is usually made of a thermosetting resin or a mixed resin of a thermosetting resin and a thermoplastic resin, and contains a curing agent for the thermosetting resin. The matrix resin is prepared to have a predetermined composition and is, for example, a block-shaped resin. This block-shaped resin is melted by a coater and coated on a release sheet with a predetermined thickness, and the resin-supported release sheet is used to transfer and impregnate into reinforcing fibers. A prepreg consisting of and is manufactured.

The matrix resin has been conventionally prepared, for example, as follows.

Stir a thermosetting resin or a mixed resin of different thermosetting resins or a mixed resin of a thermosetting resin and a thermoplastic resin at a relatively high temperature (for example, 150 ° C.) with a stirrer (kneader),
The matrix resin was prepared by mixing and cooling the mixture to a relatively low temperature (for example, 60 ° C.), and then adding a curing agent and stirring and mixing again. The reason why the temperature is lowered when adding the curing agent is to prevent the curing from progressing at the stage of resin preparation.

[Problems to be Solved by the Invention] However, the conventional resin preparation methods described above have the following problems.

Some hardeners for thermosetting resins are in the form of powder, but such powder hardeners, in particular, fine powder hardeners having a volume average particle size of 100 μm or less are aggregated. It is easy to do, and when added and mixed, it easily becomes a powder. If such powder is generated, it becomes difficult to coat the release sheet with the resin uniformly, which may lead to uneven coating thickness and streak-like defects. When the resin-supported release sheet having these defects is used to transfer and impregnate the reinforcing fibers, the adverse effects of these defects are directly transferred to the prepreg to be produced,
The resulting prepreg has uneven impregnation and streaky defects.

The present invention focuses on the above-mentioned problems, and when preparing a matrix resin for a prepreg, aims to prevent the occurrence of powdered powder due to a fine powder curing agent, and ultimately, impregnation unevenness and stripe defects. It is an object of the present invention to provide a prepreg in which a fine powder curing agent is finely and uniformly dispersed.

[Means for Solving the Problems] A method for preparing a matrix resin for a prepreg according to the present invention which meets this object is a thermosetting resin and a viscosity at 50 ° C. of 30.
In preparing a matrix resin containing a low-viscosity resin having a volume average particle diameter of 100 μm or less and a low-viscosity resin having a viscosity of 000 centipoise or less, at least a portion of the low-viscosity resin of the matrix resin, and The method comprises mixing a fine powder curing agent in advance, passing the mixture between rolls to peptize the fine powder curing agent, and then mixing the peptized mixture with the rest of the matrix resin.

At least a part of the matrix resin is made of a thermosetting resin.

The preferred thermosetting resin used in the present invention, epoxy resin, maleimide resin, polyimide resin, acetylene terminal resin, vinyl terminal resin, allyl terminal resin, nadic acid terminal resin, cyanate ester terminal Resins having It is also possible to appropriately mix and use these thermosetting resins.

An epoxy resin is used as the thermosetting resin suitable for the present invention. In particular, epoxy resins having an amine, a phenol, or a compound having a carbon-carbon double bond as a precursor are preferable. Specifically, as epoxy resins having amines as precursors, tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidylaminofresol, and phenols are used. As the precursor epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a compound having a carbon-carbon double bond is used as a precursor. Examples of the epoxy resin to be used include, but are not limited to, alicyclic epoxy resins. Brominated epoxy resins obtained by brominating these epoxy resins can also be used. Epoxy resins having an aromatic amine as a precursor typified by tetraglycidyldiaminodiphenylmethane are most suitable for the present invention because they have good heat resistance and good adhesion to reinforcing fibers.

The thermosetting resin has the above-mentioned volume average particle diameter of 100 μm.
It is used in combination with the following fine powder curing agent. A compound having an amino group, an acid anhydride group or an azide group is suitable as the curing agent. Specifically, dicyandiamide (which is particularly prone to powdering), various isomers of diaminodiphenyl sulfone, and aminobenzoic acid esters are suitable.
More specifically, dicyandiamide is preferred because it has excellent storage stability for prepreg. Various isomers of diamminodiphenyl sulfone are preferably used because they give a cured product having good heat resistance. As the aminobenzoic acid esters, trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-aminobenzoate are preferably used. Although they are inferior in heat resistance to diaminodiphenyl sulfone, they have high tensile strength. Since it is excellent, it is selected and used according to the application.

In the present invention, it is also suitable to use a thermoplastic resin mixed with the above thermosetting resin as the matrix resin.
The thermoplastic resin suitable for the present invention has a carbon-carbon bond, an amide bond, an imide bond, an ester bond, an ether bond, a carbonate bond, a urethane bond, a urea bond, a thioether bond, a sulfone bond, an imidazole bond, and a carbonyl bond in the main chain. A thermoplastic resin having a bond selected from, more preferably polyacrylate, polyamide, polyaramid, polyester, polycarbonate,
Polyphenylene sulfide, polybenzimidazole,
It is a group of thermoplastic resins belonging to engineering plastics such as polyimide, polyetherimide, polysulfone, polyethersulfone, and polyetheretherketone. In particular, polyimide, polyetherimide, polysulone, polyethersulfone, and polyetheretherketone are suitable for the present invention because they have excellent heat resistance.

As the thermoplastic resin, a commercially available polymer may be used, or a so-called oligomer having a lower molecular weight than the commercially available polymer may be used. As the oligomer, an oligomer having a functional group capable of reacting with the thermosetting resin at the terminal or in the molecular chain is more preferable.

Thus, the mixture of thermosetting resin and thermoplastic resin gives better results than when the thermosetting resin is used alone. This is because thermosetting resins can be low-pressure molded by an autoclave while generally having a brittle defect, whereas thermoplastic resins are generally tough, but low-pressure molding by an autoclave is difficult. This is because they have the trade-off property of being present, and the physical properties and moldability can be balanced by using them in combination. The thermoplastic resin component relative to 100 parts by weight of the matrix resin is preferably 50 wt% or less, more preferably 30
It is less than or equal to wt.

Now, in the present invention, in the preparation of the matrix resin, in addition to the thermosetting resin, the viscosity at 50 ℃ is 3000
Prepare a low-viscosity resin that is 0 centipoise or less. The type of resin is selected from those mentioned above. It may be a thermosetting resin or a thermoplastic resin. In short, the resin itself has a viscosity of 30,000 centipoise or less originally at 50 ° C, or
Any resin may be used as long as it has a viscosity at 50 ° C. of 30,000 centipoise or less. Here, if the viscosity of the low-viscosity resin at 50 ° C. exceeds 30,000 centipoise, the viscosity when mixed with a fine powder curing agent afterwards becomes too high, and even if pressed between rolls, the powder of the curing agent is not powdered. It cannot be resolved. The proportion of the low-viscosity resin used is determined in consideration of the required characteristics and the like. Then, first, all or a part of the above low-viscosity resin is used, and it is mixed with the fine powder curing agent.

This mixing produces a flour in the fine powder curing agent, but the mixture is pressed between each pair of rolls arranged in parallel, preferably at least three rolls, to crush the flour. That is, the mixed low-viscosity resin and the hardener made of powder are passed while being pressed between a pair of three rolls, so that the hardened agent that is agglomerated is crushed between the rolls. And broken into agglomerates, and molded on a sheet while being mixed with a low viscosity resin. Subsequently, it is passed through another pair of rolls and further mixed and molded while being crushed. By the crushing between the rolls, the joint powder by the curing agent is crushed almost completely, and the curing agent is kneaded into the low-viscosity resin substantially uniformly. Between the rolls of the first stage, the jointed powder was almost crushed, and the mixture with the low-viscosity resin was molded into a roughly sheet shape,
Between the second-stage rolls, the jointed powder is more completely crushed and made uniform.

The mixture, which is mixed with the low-viscosity resin component without being powdered by the curing agent, is mixed with the remaining necessary components of the matrix resin. This mixing may be performed by heating, melting, stirring and mixing using a kneader as in the conventional method. Since the curing agent is kneaded in advance into the low-viscosity resin in the absence of powder, no powder will be generated even at the stage of mixing with the kneader. Accordingly, the curing agent is dispersed in a state where it does not aggregate, and a matrix resin having a predetermined composition is prepared. In addition,
Since some hardeners are in a free-flowing state and are extremely unlikely to be powdered by nature, when used with such a curing agent, a curing agent that easily becomes powdered is recommended.
The low-viscosity resin may be kneaded in advance using the present roll, and the curing agent that is unlikely to be powdered may be mixed in the subsequent mixing with other resin components.

As described above, the matrix resin prepared without being powdered by the curing agent is coated on the release sheet with a coater, for example. Since there is no continuous powder, the melted resin easily and uniformly flows, is uniformly controlled to a desired coating thickness, and is uniformly coated on the release sheet. By using this evenly coated resin-supported release sheet to transfer and impregnate the resin into the reinforcing fibers, it becomes possible to prepare a uniform prepreg free from uneven impregnation, streak-like defects and the like.

[Examples] Hereinafter, preferred examples of the present invention will be shown, and the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a three-roll apparatus for carrying out a method for preparing a matrix resin for prepreg according to an embodiment of the present invention.

In FIG. 1, three rolls 1, 2 and 3 are arranged in parallel with each other, and the space between the rolls 1 and 2 and the space between the rolls 2 and 3 are set to a predetermined clearance set in advance. . At least a part of the low-viscosity resin component of the resin components constituting the matrix resin and the fine powder curing agent that easily causes powdering are mixed in advance by an appropriate mixing device. This mixture 4 is fed between the rolls 1 and 2.

By rotating the rolls 1, 2 in the direction of the arrow, the mixture is passed through a narrow clearance between the rolls 1, 2. In the mixture 4 with the above-mentioned curing agent, the joint powder in the state where the curing agent is agglomerated is generated, but when the mixture 4 is pressed between the rolls 1 and 2, the generated joint powder is crushed. Be done. By pressing between the rolls 1 and 2,
Almost all the crushed powder is crushed and returned to the powder state. Even in this state, it is possible to send it to the next mixing step,
In order to crush the powder more reliably, continue to roll 2,
Passed between 3

The clearance between the rolls 2 and 3 is narrower than that between the rolls 1 and 2, and it is desirable to set the pressing force by the rolls 2 and 3 to be higher than that by the rolls 1 and 2. The continuous powder is substantially completely crushed, and the crushed powder curing agent is substantially uniformly kneaded into the low-viscosity resin.

This mixture is mixed with the remaining components of the matrix resin. This remaining component is mainly the resin component remaining in the matrix resin, but at this stage, a curing agent (for example, a curing agent that does not easily cause powdering) may be added, and a curing catalyst and other additives may be added. May be.

The matrix resin thus prepared is molded into a block shape, for example, and is provided for coating on a release sheet. The coating is performed with a coater as shown in FIG. 2, for example.

The coater 40 shown in FIG. 2 is a reverse roll type coater, in which the release sheet 43 alone is unwound from the roll 42 set in the unwinder 41, and is passed over the coating roll 44 via the applicator roll 45. The molten resin 46 for coating continuously supplied is coated on one surface of the release sheet 43. Whether or not it has a predetermined coating thickness,
For example, the thickness is checked by measuring the thickness of the release sheet 43 alone and the resin-coated release sheet 43 with a β-ray basis weight meter 47, and the release sheet 43 is wound around the roll 48 as the resin-supported release sheet 43. The roll 48 is used in the prepreg making process.

The coating resin 46 is obtained by melting the resin block 49 made of the matrix resin adjusted as described above with the heating roll 50 as a melter and applying the molten resin to the applicator roll.
On the applicator roll 45, the molten resin supply amount is controlled by adjusting the clearance between the applicator roll 45 and the metering roll 51, the peripheral speed of both rolls, and the temperature. Are transferred and coated on the release sheet 43. The heating roll 50, the applicator roll 45, the metering roll 51, and the coating roll 44 are, for example, the internal heater 5
The heating is controlled by 2, 53, 54, 55 or a heat medium.

To control the coating thickness of the molten resin 46, adjustment of the clearance between the applicator roll 45 and the metering roll 51 is particularly important, and this clearance is usually set to an extremely small value. Therefore, if the continuous powder of the curing agent remains in the resin block 49, it also remains in the molten resin 46, which impedes the flow of the molten resin when passing between the rolls 45 and 51, and thus on the release sheet 43. If there are streaky defects in the coating on the roll or if there is a large amount of powder, roll
Since it cannot pass between 45 and 51, it causes defects such as rough coating unevenness and partial coating resin composition nonuniformity. However, in the present invention, since the resin block 49 does not substantially contain the powdered powder, the above-mentioned defects do not occur, and the release sheet 43 is used.
The desired uniform coating on top is possible.

In this way, the resin-supported release sheet uniformly and accurately coated to a predetermined thickness is used for prepreg preparation.

[Effects of the Invention] As described above, according to the method for preparing a matrix resin for a prepreg of the present invention, it is possible to prevent the occurrence of powdering by a curing agent for a thermosetting resin. In addition, a curing agent composed of fine powder can be kneaded in a uniform dispersed state without aggregation, and by using the mixed resin, the matrix resin is evenly applied at the stage of coating the release sheet without unevenness. The release sheet can be coated with a uniform thickness and without streaky defects. Transfer to reinforcing fibers using this resin-supported release sheet,
By impregnating, a prepreg having uniform physical properties without streaky impregnation unevenness can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic side view of a three-roll apparatus for carrying out the method according to one embodiment of the present invention, and FIG. 2 is a matrix resin prepared by using the apparatus of FIG. 1 on a release sheet. It is a side view of a coater to coat. 1, 2, 3 …… Roll 4 …… Mixture of low viscosity resin and curing agent 40 …… Coater 41 …… Unwinder 43 …… Release sheet 44 …… Coating roll 45 …… Applicator roll 46 …… Molten resin for coating 47 …… Match weight 49 …… Resin block 50 …… Heating roll as melter 51 …… Metaling roll

Claims (1)

[Claims] 1. A thermosetting resin having a viscosity of 3000 at 50 ° C.
In preparing a matrix resin containing a low-viscosity resin of 0 centipoise or less and a fine powder curing agent having a volume average particle size of 100 μm or less, at least a part of the matrix resin, and the low-viscosity resin described above, A fine powder curing agent is mixed in advance, the mixture is passed between rolls to deflocculate the fine powder curing agent, and then the deflocculated mixture is mixed with the rest of the matrix resin. , Method for preparing matrix resin for prepreg.