JPH03207610A - Manufacture of prepreg - Google Patents

Abstract

PURPOSE:To enhance the uniformity of physical properties and the quality of a prepreg by a method wherein the viscosity of resin on a release sheet positioned on a large diameter roll side is higher than that of resin on a release sheet positioned on a small diameter roll side so that the viscosity of the resins at the time of heating and pressing by press rolls becomes substantially equal on both surface sides of a sheetlike reinforcing fiber. CONSTITUTION:Upper and lower release sheets 12, 13 are taken out of rolls 15, 16, and their running directions are changed by guide rolls 17, 18, whereby the release sheets 12, 13 are laminated on the upper and lower sides of a sheetlike reinforcing fiber 11. After the laminate is heated by upper and lower heating plates 19, 20, it is allowed to pass through three-stage press rolls 21 to be pressed from the upper and lower sides thereof, so that resins 14a, 14b carried by the release sheets are transferred to the reinforcing fiber 11 into which the resins are infiltrated, and thus a prepreg 22 is formed. Prior to heating and pressing by the press rolls 21, the resins carried by the release sheets are so selected that the viscosity of the resin 14b on the release sheet 13 positioned on the large diameter roll side is higher than that of the resin 14a on the release sheet 12 positioned on the small diameter roll side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a sheet-like prepreg used in a certain form of fiber-reinforced composite material, and in particular to a method optimal for use in producing cloth prepreg.

[Prior art] Fiber-reinforced composite + J 1.1 sea used for precepts]・
Conventionally, for example, as shown in FIG. 3, the shape prepreg is made by forming a sheet i between two release sheets 1, 1, and 3 that carry exactly the same resin (for example, B-Stage thermosetting resin) on one side.
The reinforcing fibers 2 arranged in the shape of ~ are supported, heated and pressed by a heating means (heating plate) 4 and a press roll 5 to transfer and impregnate the reinforcing fibers 2 with resin to produce a prepreg 6. It is manufactured by a method of peeling off the mold sheet 1 and 3 and winding up the prepreg 6 together with the other mold sheet 1 and 1 into a roll shape. During use, the prepreg produced by this method is peeled off from one side of the prepreg, and multiple sheets are laminated in the same direction or in different directions depending on the necessity, forming a fiber reinforced composite material in a certain shape. Served.

In the above-mentioned method for producing Buri Preg, a pair of upper and lower rolls (press rolls 5) are used to apply pressure for resin impregnation.
However, in order to increase the linear pressure of press rolls, one (usually the upper) roll 5a is usually a small diameter roll, and the other roll 5b is a large diameter roll with a larger diameter. In order to promote resin impregnation, the large-diameter roll 5b is usually a heated roll, for example, a roll with an embedded heater, and heating and pressure are applied at the same time at the press roll 5.

[Problems to be Solved by the Invention] However, in the prepreg manufacturing process as described above, the following problems may occur in the position of the press roll.

The stack of reinforcing fibers 2 and resin-supported release sheets 1 and 3 is heated also at the press roll, but only the large diameter roll 5b side is heated by the heating roll, so the upper and lower surfaces are heated in this position. The amounts are considerably different, and the resin supported on the lower release sheet 1 becomes hotter, resulting in a difference in viscosity between the upper and lower resins. Even if the small-diameter roll 5a is also subjected to heating rolls, the difference in contact area with the large-diameter roll 5b will still cause a temperature difference between the upper and lower supporting resins, resulting in a viscosity difference. When such a viscosity difference occurs, the reinforcing fiber 2
Since the rate of resin impregnation into the prepreg varies, there is a risk of uneven impregnation occurring in the thickness direction and planar direction of the prepreg.

In general, the lower the viscosity of the resin, the better its impregnation into the reinforced pA fibers.In order to lower the viscosity of the resin, it is sufficient to raise the temperature of the resin, but if the temperature is continuously raised, the resin will harden. The tackiness (stickiness) of the pre-preg that has progressed too much and has been shaped.
Drapability (the ability to easily follow the shape) is impaired,
The heating temperature of the resin must be kept at an appropriate temperature. However, if the heating temperature by the large diameter roll 5b is suppressed and the temperature of the supporting resin on the mold release seams 1 and 1 side is suppressed to a certain appropriate temperature, the temperature of the supported resin on the mold release seams 1 and 3 on the small diameter roll 5a side will be lower than that. Since the temperature is also considerably low, the above-mentioned viscosity difference occurs, and the impregnating property of the mold release sheet 3-supporting resin deteriorates. On the other hand, when the resin supporting the release sheet 1 and 3 is heated to the appropriate temperature and viscosity, the temperature of the resin supporting the release sheet 1 on the large diameter roll 5b side becomes too high.
Viscosity becomes too low. If the resin humidity becomes too high, the tackiness and drape properties will be impaired as mentioned above, but
In addition, the following major problems arise when the viscosity becomes too low.

As shown in FIG. 4, the resin 7 on the large-diameter roll 5b side is heated to a higher degree and has a lower viscosity than the resin on the small-diameter roll 5a side.・
The overlapping body of 1 and 3 is a large diameter roll 5b and a small diameter roll 58.
When pressed between the rollers, the resin on the large-diameter roll 5b side is squeezed out, and a resin pool 8 is generated in a portion immediately before the nip point of the two-hole rollers. When such a resin pool 8 occurs, the reinforcing fibers 2 are pushed in an undesirable direction (in FIG. 4, they are curved upwards), and the reinforcing fibers 2 arranged in a seal shape become disordered, causing the prepreg to deteriorate. This will lead to deterioration of physical properties and non-uniformity.

The present invention focuses on the above-mentioned problems, and aims to impregnate release sheet-carrying resin from both sides of uniform reinforcing fibers well and uniformly to the same degree, and to impregnate the resin on the large-diameter press roll side. It is a woman's task to minimize the resin accumulation that occurs or tends to occur to a non-problematic level,
By achieving this goal, the object is to make the physical properties of prepregs, particularly cloth prepregs, uniform and improve their quality.

[Means for Solving the Problems] A method for producing a brev leg of the present invention in accordance with this objective is to superimpose a release sheet carrying a resin on each surface of a sheet 1-shaped reinforcing fiber on each surface. The stacked body is heated and pressurized by passing it between press rolls consisting of a small diameter roll and a large diameter roll, and at least the large diameter roll has a heating hole, thereby converting the resin into sheet-like reinforcing fibers. In the method for manufacturing a prepreg in which the prepreg is transferred and impregnated from both sides of the reinforcing fiber, the large diameter One method is to make the viscosity of the resin on the release sheet 1 located on the roll side higher than the viscosity of the resin 6 on the release sheet located on the small diameter roll side.

In other words, in the present invention, a viscosity difference is given to the resin on both release sheets, and the resin on the release sheet located on the large-diameter press roll side has a higher viscosity, so that Both resins have substantially the same viscosity when heated and pressurized.

[Function] In such a method, even if the amount of heating is greater for the resin on the large-diameter roll side and the temperature is higher than that of the resin on the small-diameter roll side, the viscosity of the former is set higher than that of the latter. Therefore, the viscosity of the resin on both surfaces of the reinforcing fibers can be made to be substantially equal at the heating and pressurizing position by the press roll.

When the viscosities become substantially equal, the rate of resin impregnation (degree of impregnation) from both sides of the reinforcing fiber also becomes substantially equal, achieving uniform resin impregnation. In relation to the resin temperature, the viscosity is optimal for impregnating the reinforcing fibers without impairing tackiness or drape properties, so that the resin can be injected from both sides of the reinforcing fibers in the most desirable state. It becomes possible to impregnate.

In addition, since the viscosity of the resin on both sides of the reinforcing fiber can be made substantially equal by heating with the press roll and at the IJ mouth pressure position, it is possible to easily make large diameter rolls without impairing resin impregnation from the small diameter roll side. It is possible to minimize the occurrence of resin accumulation on the roll side. Therefore, the occurrence of disorder in the reinforcing fiber arrangement due to resin pooling is easily prevented, and the physical properties of the prepared prepreg are made uniform and its quality is improved.

[Embodiments] Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a prepreg manufacturing method according to an embodiment of the present invention. In the figure, reference numeral 11 indicates reinforcing fibers arranged in a sheet shape, and 12 and 13 indicate a release sheet 1 that supports resins 14a and 14b on one side (on the reinforcing fiber side).
- are shown respectively.

In Figure 1, the upper and lower release seals 12 and 13 are
It is unwound from the guides [1-17, 1].
At 8, the direction is changed, and the reinforcing fibers 11 are stacked on top of each other. After being heated by the heater heating plates 19 and 20 of the stacked body, the resin 14a was passed through three stages of press rolls 21, and was pressurized from above and below, and was supported on the mold release sheet 1. 14b is transferred and impregnated into the reinforcing fibers 11, and the prepreg 22 is formed.

The three stages of press rolls 21 each consist of a pair of rolls 23, 24, 25, 26, 27, and 28,
The upper rolls 23, 25, and 27 are small-diameter rolls, and the lower holes 24, 26, and 28 are large-diameter rolls.

Each of the large-diameter rolls 24, 26, and 28 is a heating roll in which heaters 29a, 29b, and 29c are embedded, respectively, and each heater is connected to a heater control device 30 and a heater power source 31.

The reinforcing fibers used in the present invention include carbon fibers, black & 41 fibers, organic high-modulus fibers (such as aramid fibers), silicon carbide fibers, alumina fibers, boron fibers, tungsten carbide fibers, and high-strength fibers such as glass fibers. , high modulus fibers. Only one type of such reinforcing fibers may be used for the same prepreg, or different types of reinforcing fibers may be used. These reinforcing fibers It is listed in the form.

Normally, unidirectional prepreg is most suitable for applications that require high specific strength and specific modulus, but prepregs pre-processed into sheets such as long fiber mats and woven fabrics can also be used. can.

The release sheet used in the present invention is a release paper, such as clay, starch, polyethylene, polyvinyl alcohol, etc. A silicone or non-silicone mold release agent, preferably a condensation reaction type or addition reaction type of polydimethylsiloxane and polydimethylhydrodienesiloxane, is provided on each coating layer. It is like applying a mold release agent made of silicone. It is also possible to use a resin film that has been given release properties by corona discharge treatment or the like, or a resin film that has been coated with a release agent (eg, polyethylene film, polypropylene film, etc.).

10 The resins 14a and 14b supported on the release sheet 12 and the release sheet 13 include thermosetting resins and resins that are a mixture of thermosetting resins and thermoplastic resins. Examples of thermosetting resins include epoxy resins, maleimide resins, polyimide resins, resins with acetylene ends, resins with vinyl ends, resins with allyl ends, resins with nadic acid ends, and resins with cyanate ester ends. It will be done.

These can generally be used in combination with a curing agent or a curing catalyst. Moreover, it is also possible to use a mixture of these thermosetting resins as appropriate.

Epoxy resin is also used as a thermosetting resin suitable for prepreg production. Particularly preferred are epoxy resins whose precursors are amines, phenols, and compounds having carbon-carbon double bonds. Specifically, as epoxy resins using amines as precursors, various isomers of te]~laglycidyldiaminodiphenylmethane, triglycidyl-p-amine phenol, triglycidyl-m-amine phenol, triglycidylaminofresol, and phenols. Previous 11 Epoxy resins used as precursors include bis71nol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and carbon-carbon double bond. An epoxy resin whose precursor is a compound of
-Epoxy resins whose precursors are aromatic amines such as laglicidyl diaminodiphenylmethane have good heat resistance and good adhesion to reinforcing fibers, so they are most suitable for making bripregs as described above. These epoxy resins are preferably used in combination with an epoxy curing agent. As the epoxy curing agent, any compound having an active group capable of reacting with the earth boxy group can be used.

In general, it is also suitable to use a mixture of the thermosetting resin described above and a thermoplastic resin. The thermoplastic resin to be mixed has carbon-carbon bonds, amide bonds, imide bonds, ester bonds, ether bonds, carbonate bonds, urethane bonds, urea bonds, thioether bonds, sulfone bonds, imidazole bonds, A thermoplastic resin having a bond selected from carbonyl bonds, more preferably polyacrylate, polyamide, polyaramid, polyester, polycarboner 1-, polynoenylene sulfide, polybenzimidazole, polyimide, polyetherimide, and borisulfone. It is a group of thermoplastic resins that belong to engineering plastics such as polyethers, polyethers, rubbers, polyetherethers, etc. In particular, polyimide, polyetherimide, polysulfone, polyether sulfone, and polyether ether carbon are most suitable because they have excellent heat resistance.

The resin to be supported on the release sheets 12 and 13 is selected from the resins mentioned above. Before heating and pressurizing this supported resin by the press roll 21, the viscosity of the resin 14b on the release sheet 13 located on the large-diameter roll side is lower than that of the resin 14b on the release sheet 12 located on the small-diameter roll side. The viscosity is selected to be higher than that of 14a. In other words, the selection is such that the viscosity of each resin 14a and 14b at the heating and pressurizing position by the press roll becomes the same in actual purchase. Such a selection can be easily made by taking into account the type and composition of the resin, and the change in resin viscosity over time when the resin-supported release sheet is stored.

By setting the resin viscosity in this way, each pair of press rolls 23
, 24, 25, 26, or 27, 28, even if there is inevitably a difference in the amount of heating for the upper and lower resins 14a, 14b, it is possible to make the viscosity of both resins 14a, 14b the same in commercial terms. Each resin 14a, 14
The resin can be impregnated extremely uniformly from both surfaces of the reinforced S fibers 11 while ensuring that the thermal history to b does not impair the tackiness and drapability of the prepreg.

In addition, since the resin 14b located on the large-diameter roll side is controlled to have the optimum viscosity for impregnating the reinforcing fibers, the occurrence of resin pooling at the position immediately before each large-diameter roll 24, 26, 28 can be suppressed. Even if it occurs, it can be minimized to the extent that it does not cause any problems. Therefore, occurrence of disorder in the arrangement of the sheet 1-shaped reinforcing fibers 11 is prevented.

[Effects of the Invention] As explained above, when using the pre-reg manufacturing method of the present invention, the resin on the release sheet located on each side of the large-diameter press roll and the small-diameter press roll has a viscosity difference, and the press roll The heating and pressurizing position substantially eliminates the viscosity difference between both supported resins, and the viscosity of both supported resins at that position is easily heated to the optimum viscosity for inclusion into reinforcing fibers. Since the amount can be controlled, resin can be impregnated uniformly from both sides of the reinforcing fibers, and the occurrence of resin accumulation just before the large-diameter roll can be minimized to a non-problematic level, resulting in sheet-like reinforcement. It is possible to prevent the occurrence of disorder in the arrangement of the fibers Ift. As a result, a high-quality Bripreg with extremely uniform physical properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of a prepreg manufacturing apparatus for implementing the prepreg manufacturing method of the present invention, FIG. 2 is an enlarged side view of the press roll part and its vicinity in the process of FIG. 1, and FIG. 11 is a schematic side view of the conventional prepreg manufacturing process, and FIG. 4 is an enlarged vertical cross-sectional view of the press roll part that is applied to the process of FIG. ...Release sheet 14a, 1!lb...Supporting resin 19, 20.
...Heater 21...Press roll 22...Prepreg 23, 25, 27...Small diameter rolls 24, 26,
28... Large diameter rolls 29a, 29b,
29c ・------ Heater 30... Heater control device 31... Heater power supply 16

Claims (1)

[Claims] 1. A release sheet carrying a resin on one side is superimposed on each side of the sheet-like reinforcing fiber, and the superimposed body is made up of a small diameter roll and a large diameter roll, and at least a large diameter roll. In a prepreg manufacturing method in which the resin is transferred and impregnated from both sides of the sheet-like reinforcing fibers by passing between press rolls, which are heating rolls, and applying heat and pressure, the prepreg is heated and pressurized by the press rolls. In order to make the viscosity of the resin substantially equal on both sides of the sheet-like reinforcing fibers, the viscosity of the resin on the release sheet located on the large-diameter roll side is set to be equal to the viscosity of the resin on the release sheet located on the small-diameter roll side. A prepreg manufacturing method characterized by keeping the viscosity higher than that of the resin.