JPH0724830A - Production of thermoplastic unidirectional prepreg sheet - Google Patents

Abstract

PURPOSE:To produce a wide thermoplastic unidirectional prepreg sheet good in the impregnation with a resin and free from the disturbance of fibers at a high speed. CONSTITUTION:Continuous reinforcing fiber tows are impregnated with a thermoplastic resin to be formed into a tape shape. A plurality of the tape-shaped two prepregs thus formed are arranged in a lateral direction and pressed under heating to be formed into a sheet.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a thermoplastic unidirectional prepreg sheet. More specifically, the invention relates to a high-speed manufacturing method of a wide thermoplastic unidirectional prepreg sheet.

The thermoplastic unidirectional prepreg sheet of the present invention has a wide width and can be produced at a high speed, but the glass fiber is well impregnated with the resin, there are no bubbles, and the fiber is dispersed in a preferable state. Therefore, it has excellent cost / performance characteristics and can be used as automobile materials, electric / electronic materials, building materials, aircraft materials, and the like.

[0003]

2. Description of the Related Art Composite materials using a thermoplastic resin as a matrix have been in the limelight in recent years because of their excellent toughness, moldability, storage characteristics, repairability and recyclability. A basic intermediate material used for molding a thermoplastic composite material is a thermoplastic unidirectional prepreg sheet (hereinafter abbreviated as prepreg sheet).

In the production, generally, a large number of fibers are aligned and formed into a sheet, and then impregnated with a resin to obtain a sheet-like prepreg. However, its production rate was extremely slow, at 1 m / min or less. The reason for this is that it is difficult to impregnate the glass fiber with the thermoplastic resin due to its high melt viscosity, and further, the fiber breaks, fluffs and the like during high speed production.

Attempts have been made to ameliorate this drawback and increase the production rate of prepregs. One of them is a method of powdering a thermoplastic resin to impregnate fibers. However, this method is difficult to completely remove air bubbles from the prepreg, in addition to the fact that the resin is limited to powder, and is generally limited to the production of narrow strand-shaped or tape-shaped prepreg. Is the actual condition (Japanese Patent Laid-Open No. 60-36156, Japanese Patent Laid-Open No. 58-50194, etc.) Also, as a method of directly impregnating the molten resin into the fiber,
Die with pressure chamber (US Pat. No. 3,939,372)
6) and a die incorporating a rod (Japanese Patent Laid-Open No. 61-4011)
Although 3) and the like have been proposed, the shape of the prepreg is limited to a narrow one. Further, although attempts have been made to increase the speed by a method in which a thermoplastic resin is made fibrous and mixed with reinforcing fibers, it is intended to manufacture a prepreg in the form of a strand or a tape (Japanese Patent Laid-Open Nos. 4-62108 and 4-62). 6
2111, flat 4-185313, flat 2-173121, etc.).

There is also disclosed a method of producing an adhered material in which a thermoplastic resin is adhered to a reinforcing fiber bundle, and arranging a large number of these to heat and pressurize the resin to manufacture a prepreg sheet impregnated with the resin (Japanese Patent Laid-Open No. 59-59-59). 62114, Sho 60-3613
6) However, since it is necessary to carry out the impregnation operation at the time of heating and pressurization, it is difficult to speed up the process.

[0007]

DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION As described above, in the conventional technology, the prepreg sheet has a narrow width,
It could not be manufactured at high speed. The purpose of the present invention is to
It is an object of the present invention to provide a method for producing a wide-width thermoplastic unidirectional prepreg in a wide sheet shape at a high speed, which solves the drawbacks of the prior art.

[0008]

According to the present invention, a tow of continuous reinforcing fibers is impregnated with a thermoplastic resin, and at the same time, a plurality of tow prepregs in the form of a tape are aligned in the width direction and arranged, and then heated. The problem was solved by applying pressure to form a sheet.

Examples of the continuous reinforcing fiber in the present invention include known fibers such as glass fiber, carbon fiber, aramid fiber, polyethylene fiber, liquid crystal polymer fiber, polyphenylene sulfide fiber, alumina fiber, silicon carbide fiber, metal fiber and combinations thereof. To be These fibers (monofilaments) generally have a diameter of 4 to 30 μm. These fibers are usually subjected to a known surface treatment in order to improve the affinity with the resin.

The continuous reinforcing fiber tow of the present invention has a large number of tows.
Typically, it is a bundle of about 1000 to 15000 monofilaments. In this case, a known sizing agent is used.

Examples of the thermoplastic resin of the present invention include the well-known thermoplastic resins. For example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethylmethacrylate nylon 6, nylon 6
6, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyphenylene oxide, polyacetal, polysulfone, polyether sulfone, polyarylate, polyphenylene sulfide,
Polyether ether ketone, liquid crystal aromatic polyester, polyimide and the like, and their copolymers, modified products and blends of two or more of the above. In addition, in using these, known additives, modifiers, fillers and the like may be added.

The tow prepreg used in the present invention is obtained by impregnating a tow of continuous reinforcing fibers with a thermoplastic resin to form a tape. In this case, the impregnation method is not particularly limited, and various conventionally known methods can be adopted. That is, a method of removing the solvent and water after impregnating the resin into a solution or emulsion, a method of impregnating the resin by melting it after introducing it into a powder, a film, or a thread and introducing it into the fiber, or a fiber in a monomer or oligomer state. A method of impregnating the resin inside and then polymerizing it, a method of directly impregnating the resin in a molten state into the fibers (for example, by superposing the molten sheet resin and the fibers and then press-fitting the resin into the fibers, in the molten resin Such as those that are pulled through the die after introducing the fiber). Among these, the melt drawing method, which is performed by using a crosshead die attached to an extruder, is a typical method. When the tow of the continuous reinforcing fibers is impregnated with the thermoplastic resin, the number of tows is not particularly limited, but it is preferable to use one tow.

The tow prepreg of the present invention generally has a width of 3 to 20 mm and a thickness of 100 μm to 1 mm. The composition of the continuous reinforcing fiber is 15 to 65% by volume, preferably 20 to 60% by volume, and the thermoplastic resin is 35 to 85% by volume, preferably 40 to 80% by volume.

The thermoplastic unidirectional prepreg sheet of the present invention is manufactured as follows. This is shown in FIG. As shown in FIG. 1, a plurality of tow prepregs 1 wound on a bobbin are set on a krill stand 2 and sent out. In this case, it is preferable that the tension of each tow prepreg is the same. This can be achieved, for example, by controlling the delivery torque.

The tow prepregs sent out are vertically aligned by the aligning device 4 via the guide rolls 3 and arranged in the width direction. Although various kinds of aligning devices can be considered, the aligning device 5 having a comb shape as shown in FIG. 2 is the most well known. Plural tow prepregs are aligned by passing the tow prepreg between the pin 6 and the pin 6.

The tow prepregs aligned in one direction are introduced into a device such as a heating roll 7 that can be continuously pressurized under heating (a heating belt may be used) to form a sheet. In this case, a preheating device 8 is often provided to ensure sufficient heating. As the preheating method, known methods such as contact with a hot plate, circulation of hot air, and infrared radiation are used.

The heating temperature must be higher than the melting start temperature of the thermoplastic resin used. The pressurizing pressure is the shape (width, thickness) of the tow prepreg to be used, the number, the melt viscosity, the shape (width, thickness) of the prepreg sheet that is the product,
It is determined by the production speed (related to the pressurizing time) and the like.

When selecting the heating and pressurizing conditions, it is important to obtain a good fiber dispersion, but at the same time, it is required not to disturb the fiber arrangement. The heating and pressurizing operation may be performed by a multi-step process such as using two or more heat rolls as shown in FIG. 3 or using a plurality of pairs of a preheating device and heat rolls.

At the time of heating and pressing, the tow prepreg may be sandwiched between cover films or sheets and heated and pressed for the purpose of preventing foreign matter from entering the tow prepreg and preventing resin from adhering to the heating and pressing device. in this case,
The tow prepreg is sandwiched between cover films or sheets 10 unwound from the unwinding roll 9, passed through the pressing roll 11, and then heated and pressed. The cover film or sheet is required to have heat resistance to withstand the heating temperature of the tow prepreg, not adhere to a heating / pressurizing device, and be easily peeled from the tow prepreg. It should also be noted that the material and thickness affect the heat conduction during heating.

The sheet-like prepreg as described above is cooled by the cooling device 12 to be solidified, and is taken up by the take-up device 13 to become a prepreg sheet 14 as a product. When a cover film or sheet is used, the cover film or sheet sandwiched vertically by the take-up roll 16 via the pressing roll 15 is wound up.

Regarding cooling, a method of contacting with a cooling roll or a cooling plate or a method of blowing cold air is generally used. The cooling temperature may be equal to or lower than the solidification temperature of the thermoplastic resin melt used (the crystallization temperature for the crystalline resin, the glass transition temperature for the amorphous resin).

Since the present invention uses the prepreg sheet using the tow prepreg which is preliminarily impregnated with the resin and in which the fibers are well dispersed, the feeding device, the guide roll,
There is no damage or fluffing of fibers in the aligning device, and no resin impregnation operation is required. Therefore, the overall production speed can be increased. Production speed (collection speed)
Of at least 3 m / min is possible. A known device such as a nip roll or a caterpillar belt can be used as the take-up device.

The shape of the prepreg sheet produced in this manner is not particularly limited, but generally has a width of 200 m.
A thickness of 100 μm to 1 mm is used in the range of m to 1000 mm. Also, its composition matches that of the tow prepreg.

The prepreg sheet produced according to the present invention is usually laminated and then formed by various sheet forming methods (eg, autoclave, hot press, stamping, diaphragm, etc.). Molding conditions such as temperature, pressure, time, etc. cannot be generally stated because they vary depending on the prepreg sheet (resin, fiber, composition, shape, etc.) used and the molding method used, but fiber arrangement disorder, voids, resin deterioration, etc. Optimal conditions should be selected so that Further, particularly when the resin is crystalline, caution is required because the cooling conditions significantly affect the physical properties.

[0025]

EXAMPLES The contents of the present invention will be described in detail below with reference to examples. (1) Fiber content In accordance with JIS K7052, the resin of the prepreg was thermally decomposed, and the mass of the remaining fiber and the mass of the prepreg before the thermal decomposition were measured. The volume content of the fibers was calculated from these mass values and the specific gravities of the resin and the fibers. Calculation formula Wf = (M3-M1) / (M2-M1) * 1
00 Wf: Mass content of glass fiber M1: Mass of crucible M2: Mass of crucible and test piece before combustion M3: Mass of crucible and test piece after combustion Vf = Wf * ρc / ρf Vf: Volume content of glass fiber Ratio (%) ρc: Density of test piece (g / cm ³ ) ρf: Density of glass fiber (g / cm ³ )

(2) Bending characteristics Using a universal testing machine model 1185 manufactured by Instron,
Performed according to ASTM D790 (3-point bending test). The measurement was performed so that the length direction of the test piece was the fiber direction.

(3) Impregnation of Resin A prepreg sheet is visually observed and a laminate molded body cut to a length of about 1 cm is embedded with an unsaturated polyester resin, and a cross section is ground by a polishing machine (manufactured by Japan Geoscience Co., Ltd.). After precision polishing using a system polishing machine 1-1000), observation was performed with an optical microscope.

Reference Example 1 Preparation of thermoplastic tow prepreg Continuous reinforcing fiber tow (fiber diameter 17 μm, 2300 tex, aminosilane treatment), low molecular weight maleic anhydride modified polypropylene (number average molecular weight 15000, acid value 26 m)
gKOH / g, "thermoplastic resin A") and polypropylene (UBE Polypro J130G manufactured by Ube Industries, "thermoplastic resin B") are used to produce a tow prepreg with a width of 8 mm, a thickness of 500 μm and a glass fiber content of 26% by volume. did.
The manufacturing method is as follows. The glass fiber is drawn out through a crosshead die (temperature 180 ° C) to which the thermoplastic resin A is supplied, and wound in a hot-air oven (155 ° C) around a plurality of rollers perpendicular to the fiber direction to be taken out and pre-impregnated. Was produced, and the pre-impregnated material was drawn through a crosshead die (temperature: 230 ° C.) to which the thermoplastic resin B was continuously supplied in this step, and the pre-impregnated material was coated with the thermoplastic resin B. The take-up speed (drawing speed) at this time was 20 m / min.
The ratio of resin B to the entire resin (A + B) is 86% by volume.
Met.

Example 1 Twenty-four tow prepregs manufactured in Reference Example 1 were aligned with a comb-type aligning device having a pin interval of 8.3 mm, a heater temperature of 180 ° C. and a heating roll temperature of 180.
Width of 20 under conditions of ℃, pressurizing load of 7 kN and manufacturing speed of 3 m / min.
A 0 mm prepreg sheet was manufactured. In the heating and pressurizing step, two heaters and three pressure rolls as shown in FIG. 3 were used. The thickness of the prepreg sheet was 400 μm. The obtained prepreg sheet had good resin impregnation, no voids, uniform dispersion of fibers, and no disturbance in the fiber direction. Six layers of the obtained prepreg sheets were laminated and press-molded to obtain a laminated molded body having a thickness of 2 mm. In press molding, heating is performed at 160 ° C. for 1 minute without applying pressure, and then pressure is applied at 160 ° C. for 1 minute at a pressure of 1 MPa. It cooled until it became below 80 degreeC. A three-point bending test of this laminated molded body was carried out to evaluate the physical properties. Table 1 shows the obtained evaluation results.

Example 2 In Example 1, the heater temperature was changed from 180 ° C to 200 ° C.
A prepreg sheet was manufactured in exactly the same manner except that the above was changed. The thickness of the prepreg sheet was 400 μm. The obtained prepreg sheet had good resin impregnation, few voids, fibers dispersed uniformly, and there was no disturbance in the direction of the fibers. A laminated molded body was obtained in the same manner as in Example 1. Table 1 shows the obtained evaluation results.

Examples 3, 4 In Examples 1 and 2, the production speed was changed from 3 m / min to 5 m.
A prepreg sheet was manufactured in exactly the same manner except that it was changed to / min. The thickness of the prepreg sheet was 400 μm in both Example 3 and Example 4. The prepreg sheets obtained in both Example 3 and Example 4 were well impregnated with resin, had few voids, were uniformly dispersed in the fibers, and were not disturbed in the direction of the fibers. A laminated molded body was obtained in the same manner as in Example 1. Table 1 shows the obtained evaluation results.

Reference Example 2 Preparation of thermoplastic tow prepreg Continuous reinforcing fiber tow (fiber diameter 17 μm, 1150 tex, aminosilane treatment), low molecular weight maleic anhydride modified polypropylene (number average molecular weight 15000, acid value 26 m)
gKOH / g, "thermoplastic resin A") and polypropylene (UBE Polypro J950HK manufactured by Ube Industries, "thermoplastic resin B") were used, and the same manufacturing method as in Reference Example 1 was used to provide a width of 7 mm, a thickness of 300 μm, and a glass fiber content. Rate 33
A volume% tow prepreg was produced. Collection speed is 2
It was 0 m / min. Resin B for the entire resin (A + B)
Was 86% by volume.

Example 5 28 tow prepregs produced in Reference Example 2 were aligned by a comb type aligning device with a pin interval adjusted to 7.2 mm, a heater temperature of 180 ° C. and a heating roll temperature of 200.
Width of 20 under conditions of ℃, pressurizing load of 7 kN and manufacturing speed of 7 m / min.
A 0 mm prepreg sheet was manufactured. The thickness of the prepreg sheet was 250 μm. The obtained prepreg sheet was well impregnated with resin, had few voids, had fibers dispersed uniformly, and had no disturbance in the direction of the fibers.
Ten layers of the obtained prepreg sheet were laminated and press-molded to obtain a laminated molded body having a thickness of 2 mm. The press molding conditions were the same as in Example 1. 3 of this laminated compact
A point bending test was performed to evaluate the physical properties. Table 1 shows the obtained evaluation results.

[0034]

[Table 1] Table 1 ─────────────────────────────────── Fiber content rate Flexural modulus Flexural strength (volume%) ( GPa) (MPa) ─────────────────────────────────── Example 1 26 19.2 477.4 Example 2 26 20.1 490.5 Example 3 26 19.0 473.4 Example 4 26 19.5 456.2 Example 5 33 22.3 590.4 ─────────── ─────────────────────────

[0035]

According to the present invention, a wide thermoplastic unidirectional prepreg sheet having good resin impregnation, few voids and no fiber disorder can be produced at high speed. This was not possible with conventional techniques. As a result, since the thermoplastic unidirectional prepreg sheet produced by the present invention is inexpensive and has excellent physical properties, it is particularly suitable for cost / performance-oriented automobile materials, electric / electronic materials, building materials, and aircraft materials. It can be put to practical use as such.

[Brief description of drawings]

FIG. 1 is an example of a flowchart of a manufacturing apparatus related to a manufacturing method of the present invention.

FIG. 2 shows an example of a comb-type aligning device.
By changing the angle of the divided combs, it is possible to adjust the spacing of the alignment.

FIG. 3 shows an example of a flowchart of a manufacturing apparatus related to the manufacturing method of the present invention, particularly when a plurality of heating devices and heating / pressurizing rolls are used.

[Explanation of symbols] 1 tow prepreg 2 Crill stand 3 Guide roll 4 Aligning device 5 Comb type aligning device 6 Pin 7 Heating roll 8 Preheating device 9 Unwinding roll 10 Cover film or sheet 11 Holding roll 12 Cooling device 13 Rewinding Device 14 Prepreg sheet 15 Holding roll 16 Winding device

Claims (1)

[Claims] 1. A continuous reinforcing fiber tow is impregnated with a thermoplastic resin, and at the same time, a plurality of tape-shaped tow prepregs are aligned in the width direction and arranged, and then heated to form a sheet. A method for producing a characteristic thermoplastic unidirectional prepreg sheet.