JP2001213979A - Manufacturing method of prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a prepreg which can improved impregnation of a liquid resin into a fiber base material at a low cost. SOLUTION: In a manufacturing method of a prepreg, an impregnating process is that a liquid resin is impregnated from the one side of a fiber base material, particularly is impregnated under pressure using an impregnation plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a prepreg.

[0002]

2. Description of the Related Art A prepreg used for a printed wiring board or the like is formed on a fiber base such as paper, glass cloth, synthetic fiber or natural fiber or a non-woven cloth, and is heated in liquid form such as phenol, epoxy, polyester or polyimide. A cured resin (hereinafter, referred to as a liquid resin) is impregnated, the amount of the liquid resin adhered is adjusted with a squeeze roll or the like, and the liquid resin is semi-cured by thermal drying.

[0003] By the way, if bubbles remain in the prepreg,
After curing, the surface of the prepreg does not become smooth and an uneven surface is formed, and there is a problem that a prepreg which is inferior in heat resistance or the like and stable in performance cannot be obtained. For this reason, in order to improve the impregnation property of the liquid resin into the fiber base material, the time and distance for immersion in the liquid resin are set long, and the coating speed is set low. However, in such a method, productivity is low, curing for removing bubbles is insufficient, smoothness of the prepreg surface is difficult, and the solvent must be increased to lower the viscosity, resulting in high cost. There are problems such as becoming.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the impregnation of a fiber substrate with a liquid resin at low cost. It is an object of the present invention to provide a method for producing a prepreg.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a prepreg, which comprises impregnating a liquid resin from one side of a fiber base material in an impregnation step. Also, the present invention provides a method for producing a prepreg, wherein in the impregnation step, a liquid resin is dropped from the upper surface of the fiber base material and pressure impregnation is performed using an impregnation plate.

[0006] The prepreg is produced by impregnating a fibrous base material with a liquid resin containing a thermosetting resin, followed by drying. In the present invention, as the fiber base material, a glass woven fabric, a glass nonwoven fabric, an organic fiber woven fabric, an organic fiber nonwoven fabric, or the like is used.

The liquid resin to be impregnated is not particularly limited as long as it is used for the production of prepreg, and a curing agent such as an epoxy resin, dicyandiamide, an amine compound, a dicarboxylic anhydride, and a curing accelerator such as an imidazole compound. An epoxy resin composition or the like containing an agent and a filler such as talc, silica, aluminum hydroxide and the like, which is added as needed, is used in a liquid state. Liquid resin is methanol, ethanol, acetone, methyl ethyl ketone,
A resin in which a resin component or other components are dissolved or dispersed in an organic solvent such as ethylene glycol monomethyl ether or N, N-dimethylacetamide is preferable, but a liquid (with heating or at room temperature) without using a solvent is preferable. May be used.

[0008] The amount of liquid resin impregnated into the fiber base material is appropriately determined based on the base material used and the required characteristics of the prepreg to be produced. Is preferably adjusted to 40 to 70% by weight. After the impregnation, the prepreg is dried at an appropriate temperature to bring the thermosetting component in the liquid resin into a B-stage state, thereby forming a prepreg.

Further, by impregnating the liquid resin from one of the fiber substrates, particularly from above, the liquid resin is allowed to pass through the fiber substrate, thereby removing air bubbles in the fiber substrate, and efficiently removing the liquid resin. Can be impregnated.

After the liquid resin is dropped on the fiber base material,
By gradually narrowing the gap between the fiber substrate and the impregnated plate according to the transport direction of the fiber substrate, by disposing the impregnated plate on the fiber substrate so as to press the fiber substrate from above, preferably the impregnated plate One end presses the fiber base material from the upper side, and forces the liquid resin to pass through the fiber base material, thereby removing air bubbles in the fiber base material in a short time and impregnating the liquid resin efficiently. Can be.

Next, the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of a resin impregnation device that can be used in the present invention. The fiber base material 1 is wound on a roll, and the fiber base material 1 pulled out from the roll is drawn out below the liquid resin dripping device 2 via the roll, and receives the liquid resin dripping immediately below. Subsequently, the fiber base material 1 onto which the liquid resin has been dropped is conveyed by the impregnation plate 3 such that one end thereof is pressed against the fiber base material as described above. The fibrous base material is further conveyed, immersed in the impregnation tank 5 containing the liquid resin 4, further conveyed, and passed through the drying furnace 6, and can be made into a prepreg. The fibrous base material is immersed in the impregnation tank 5 containing the liquid resin 4. This impregnates the fibrous base material by adding a liquid resin to adjust the total amount of impregnation. This step may be omitted. In addition, the liquid resin dropping device 2
The tray 7 is disposed directly below the fiber base and further below the fiber base material. It is particularly preferable that the fibrous base material be kept horizontal or almost horizontal from immediately below the liquid resin dropping device 2 until it passes through the impregnation plate 3. The dropping amount of the liquid resin is sufficient as long as the liquid resin drips from the fiber base material. FIG. 2 is a perspective view showing an example of the impregnation plate used in the present invention. The width in the transport direction of the fiber base material is A, and at right angles thereto, the width of one end on the upstream side in the transfer of the fiber base material is B, and this end is mountain-shaped so that the height is C, It is inclined to one end on the other opposite straight line

[0012]

EXAMPLE 1 As a resin impregnating apparatus, an apparatus schematically shown in FIG. 1 was used. The impregnated plate used was as shown in FIG.
A of the impregnation plate was 2000 mm, B was 1500 mm, and C was 30 mm. Liquid resin was dropped from the liquid resin dropping device 2 at a rate of 0.3 m ³ / min. As a feeding device, a winding roll (not shown) was provided on the outlet side of the drying furnace, and the winding was performed. The winding speed was 10 m / min. The liquid resin includes brominated bisphenol A type epoxy resin (manufactured by Dainippon Ink and Chemicals, DER
100 parts by weight of -518 (trade name) and 3 parts by weight of dicyandiamide were dissolved in 20 parts by weight of ethylene glycol monomethyl ether to prepare a varnish. The viscosity at 30 ° C. of the varnish was 100 mPa · s.
This varnish was placed in an impregnation tank. This varnish has a viscosity of 30
A varnish diluted to mPa · s was dropped from a liquid resin dropping device. As the fiber base material, a glass cloth (manufactured by Nitto Boseki Co., Ltd.) having a thickness of 200 μm was used. As for the drying oven, three ovens having the same length were vertically connected, and two of them were arranged. The total length of the six drying paths was 40 m. Drying is performed by raising one row as shown in FIG. 1 and then lowering the other row on the fiber base material impregnated with the liquid resin. The temperature of the drying path is 140 ° C., 160 ° C., 160 ° C. in order from the beginning. ° C, 170 ° C, 17
0 ° C. and 150 ° C. The prepreg coming out of the drying path was wound up. In the prepreg thus obtained, the proportion of bubbles per unit area when viewed from above, that is, the bubble area ratio of the prepreg was 30%. The bubble area ratio is obtained by observing the prepreg from above and measuring the ratio of the area occupied by the bubbles in a planar manner by image processing.

Comparative Example 1 A prepreg was produced in the same manner as in Example 1 except that the liquid resin dropping device and the impregnating plate were not used. As a result, the bubble area ratio of the obtained prepreg was 48%.

As is apparent from the above, it was confirmed that the impregnating apparatus according to the present invention has a higher impregnation rate of the liquid resin than the conventional apparatus.

[0015]

According to the method of the present invention, air bubbles in a fiber base material can be efficiently removed in a short time, the impregnation rate of a liquid resin into a fiber base material can be improved at low cost, and a prepreg having a smooth surface can be obtained. Can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a resin impregnation device that can be used in the present invention.

FIG. 2 is a perspective view showing an example of an impregnation plate used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fiber base material 2 Liquid resin dripping device 3 Impregnation plate 4 Liquid resin 5 Impregnation tank 6 Drying furnace 7 Receiving tray

Claims (2)

[Claims] 1. A method for producing a prepreg, wherein in the impregnation step, a liquid resin is impregnated from one side of the fiber base material. 2. A method for producing a prepreg, wherein in the impregnation step, a liquid resin is dropped from above the fiber base material and pressure impregnation is performed using an impregnation plate.