JPS6048342A - Prepreg - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to prepregs of composite materials. More specifically, the present invention relates to a novel prepreg made of a special heat-resistant fibrous nonwoven fabric and a thermosetting resin.

Prior art It is already known that prepreg is used as a composite material, and the most common one is a woven fabric made of fibers and impregnated with a thermosetting resin to make it B-stage.・Processing force: Raco's prepreg has the disadvantage of processing, that is, the complexity of handmade work.It is also known to use a piece of non-woven fabric instead of woven fabric. Always good in terms of affinity, physical properties after completion, etc.
It would be difficult to say 11 if MM should be added.

Purpose of the Invention The present inventors have conducted studies to obtain a prepreg with good performance at a low cost, and have arrived at the present invention. That is, the present invention consists only of materials that are heat resistant and flame retardant. The purpose is to provide a prepreg that is inexpensive, easy to handle, and has excellent physical properties as a composite material after resin curing.

Structure of the Invention The present invention is directed to a fiberglass fiber having a porosity of 5 to 35 cm and an air permeability of 0.1 to 0.1, which consists essentially only of heat-resistant fibers such as short aromatic polyamide fibers.
10000 seconds/100WLl.

It is a prepreg made by impregnating a thermosetting resin into a nonwoven fabric having a mode of pore distribution of 1 to 20μ.

The aromatic polyamide referred to in the present invention means that the main structural unit is monoNIL-@-NH・co@-co+ or +NH-@
A general term for polyamides that are -Co + . Among these aromatic polyamides, polymetaphenylene isophthalamide or a polyamide containing this as a main component is preferred. but,
Fibers other than aromatic polyamides can also be used.

The nonwoven fabric serving as the base material of the prepreg of the present invention is substantially composed only of heat-resistant short fibers such as aromatic polyamide, and does not contain valve particles such as "fibrids".

Conventional nonwoven fabrics generally have a very rough structure and have a porosity of more than 40%, but the nonwoven fabric that is the base material of the prepreg of the present invention has a porosity of 5 to 35%. It has a dense structure, has an air permeability in the range of 0.1 to 10,000 seconds/I 00 ml (preferably 0.7 to 7,000 seconds/100 ml), and has good resin impregnation.

Further, the nonwoven fabric has a mode of pore distribution measured with a mercury porosimeter within a range of 1 to 20 μm, and contains minute pores.

Note that the porosity, air permeability, and pore distribution of the nonwoven fabric are measured as follows.

[Porosity]

The porosity is a value representing the structural density of a nonwoven fabric, and is determined by the following formula.

1.37- (density of nonwoven fabric) Porosity (%) = x + o.

1.37 [Air permeability] Air permeability is measured according to JIS P8117IC.

[Pore distribution]

Using a mercury boron meter, a nonwoven fabric sample of 0.1 to 0.
Take 5.9 and this may be Ic 50 pH9・Abs 2
The sample is press-fitted under a pressure of 5000 psi4bs to measure the pore distribution state.

Nonwoven fabrics that exhibit the above characteristics have a structure with a very dense VC compared to conventionally known ones, and it was previously thought that it would be difficult to manufacture nonwoven fabrics with these characteristics using only fibers. Ta.

Such a nonwoven fabric can be prepared, for example, by adding dimethylborumamide, dimethyl lceto7mid, N-methyl to a web containing undrawn short fibers and/or partially drawn short fibers of aromatic polyamide, and stretched and heat-treated short fibers of aromatic polyamide. - After impregnating the fiber with 0.5 to 200% by weight of a plasticizer consisting of an amide polar solvent such as 2-pyrrolidone and/or water,
It can be produced industrially by heating and pressurizing at 200-400° C. under a linear pressure of 50-600 kg/crn using a heating roll.

Regarding such non-woven fabric itself, European patent publication @ 83
It is described in detail in the specification of No. 1037007.

On the other hand, examples of thermoplastic resins impregnated into this nonwoven fabric include phenol resin and epoxy resin.

Polyimide resins such as BT resin (bismaleimide triazine resin) are suitable.

These resins are dissolved in an organic solvent such as methyl ethyl ketone and impregnated into the nonwoven fabric.

The nonwoven fabric specified in the present invention has good impregnation properties, and is quickly and uniformly impregnated with resin.

The amount of resin impregnated varies depending on the use of the composite material, but is generally 30 to 300% by weight based on the weight of the nonwoven fabric.
It is preferably within the range of .

The resin-impregnated prepreg is molded into a predetermined shape and then heated to harden the resin, resulting in a composite phase material.

Effects of the Invention In the prepreg of the present invention, since the base fibrous material is a non-woven fabric, it can be obtained at a lower cost than those using fibrous fabrics, and it can be easily impregnated with resin, so it can be made into a prepreg. It has advantages such as easy processing, low processing cost, and good physical properties of the resulting composite material after curing the prepreg.

That is, the prepreg according to the present invention has better physical properties after curing than the prepreg using ordinary nonwoven fabric 2 synthetic paper,
When the prepreg according to the present invention is used as a structural material,
The strength after curing is superior to that of ordinary non-woven two-synthetic paper prepregs.

FIG. 1 shows an example of a honeycomb core.

The material in Figure 1 is a commercially available aramid synthetic paper [Teyupon rNomex 410 J (registered trademark), thickness 2m11
] A honeycomb core was made based on .This was immersed in a solution of MEK (methyl ethyl ketone) and phenol resin c Cemedine Co., Ltd. [Cemedine + ttoJ (registered trademark)] and dried.The obtained prepreg was cured at 120 ° C. for 120 minutes. The appearance of the obtained product represents the relationship between specific gravity and strength, and (
Bl is 1.5 de', 51 mu long aramid fiber [Music University I! ! "Konex" (registered trademark)] was made into a card and hot-pressed at 360"C and 400kg/cm using a roll press. Density: 0.7211/cd < porosity: 47cm)
Made Nicamcore with nonwoven fabric, and also made MEK of phenolic resin c ('Cemedine+ll0J (registered trademark)).
The prepreg obtained by soaking in the solution and drying was similarly heated to 120
The appearance of the product obtained by curing for 120 minutes at +°C is an expression of the relationship between specific gravity and strength, and (C) represents the strength of the product obtained by curing the prepreg according to the present invention.

As is clear from FIG. 1, the prepreg of the present invention was cured (O shows the best compressive strength).

Furthermore, when the prepreg according to the present invention is used as an electrical insulator, the dielectric breakdown voltage (B, I), V ) after curing is as follows:
It is superior to ordinary non-woven fabric 1 synthetic paper prepreg. An example of this is shown in Figure 2. (4 in Figure 2)
) is a commercially available aramid synthetic paper (rNomex manufactured by DuPont).
A sheet of 410 J (registered trademark) 2ml thick) was coated with epoxy resin [Shell Chemical Co., Ltd. "Epicoat" (registered amount [)]
828 100 copies, “Shrimp-￥-Nia ZJ (registered trademark)
20 parts of the mixture] in an MgK solution and dried.

The dielectric breakdown voltages measured after heating and curing various prepregs at 120° C. for 120 minutes are shown. fB) is 1.5 de
', 51 mm, and two types of aramid fibers with different degrees of stretching (Konex (registered trademark) manufactured by Otodai J) were made into cards, and hot-pressed at 360°C and 400 Y/G with a press roll to obtain a card with a density of 0. .70 (porosity 49%), thickness 50μ (2
mi1), and similarly made MEK of epoxy resin.
The prepreg obtained by soaking in the solution and drying was heated at 120°C for 12
The dielectric breakdown voltage measured after heating for 0 minutes is shown.

(0 indicates the dielectric breakdown voltage measured after similarly heating the prepreg of the present invention made of epoxy resin and aramid nonwoven fabric with a density of 1.05 at 120°C for 120 minutes. Shows excellent value.

As described above, the prepreg of the present invention exhibits excellent properties as a structural material and an electrical insulator, and also exhibits excellent properties such as heat resistance. It is thought that these characteristics are obtained due to the use of a nonwoven fabric made of crystal-oriented aromatic polyamide fibers. On the other hand, the characteristics of the above-mentioned structural fibers and electrical insulators are determined by structural factors, such as the spacing between fibers, the shape of the fibers after thermocompression bonding, and the size of the holes to be filled with resin, etc., within a certain range. seems important.

The present invention relates to prepregs, and is particularly suitable for prepreg sheets. This is due to the softness during processing and the liquid retention properties of the resin.

This originates from characteristics such as adhesiveness.

Example The present invention will be explained in more detail with reference to Examples below.

Note that the pore distribution in the examples is 60,000 psi type Po
rosimeter (American Instr.
0.1-0.
59 samples were pressurized from 50 microns of Hg to 25,000 psi and 11 g was injected into them for measurement.

Example 1. Comparative Example 1.2 100 mol parts of metaphenylene diamine, 95 mol parts of isophthalic acid chloride, and 15 mol parts of terephthalic acid chloride were each dissolved in tetrahydrofuran2, and an acid σ-ride solution was added to the amine solution and polymerized to form aramid. A polymer was obtained.

Intrinsic viscosity (IV
) was 1.35. This was dissolved in N-methylpyrrolidone and spun into a calcium chloride aqueous solution. This was stretched 2.4 times in a boiling water bath to obtain a boiling water drawn yarn (partially drawn yarn).

It was spun in the same manner and further stretched 1.75 times on a hot plate at 350°C to obtain a drawn yarn. Both are 1.5 de'.

This was crimped and cut into 51 tomocho pieces. Boiling water drawn yarn 6
．． The drawn yarns were mixed at a ratio of 40%, passed through a carding machine to form a web, added 100 parts of a 3-part aqueous solution of N-methylpyrrolidone to 10 parts of this web, and heated at 280°C to 200 kg.
/ca and 8 m/wax heat and pressure conditions to obtain a nonwoven fabric. The obtained nonwoven fabric has a density of 1.12. Porosity 1
8chi, basis weight 50 II/i, air permeability 10 seconds/lo
omICJIS method).

The mode of pores measured by a mercury porosimeter was 12μ. This was mixed with phenol resin [Cemedine Co., Ltd. [Cemetaine-11]
xloJ (registered trademark)] in methyl ethyl ketone solution at various concentrations to obtain prepregs with various aramid and phenol resin ratios (Example 1). The strength of this prepreg is shown in FIG.

For comparison, prepregs with various aramid and phenol resin ratios were obtained by immersing a 2 ml thick aramid synthetic paper (DuPont rNomex 410 J (registered trademark)) in the same phenolic resin solution (Comparative Example 1). The strength of this prepreg is shown in FIG. Each of these prepregs was cured by heating to 120° C. for 120 minutes. The strength is shown in Figure 4. Although the strength of the prepreg according to the present invention is rather low, it is clearly superior after curing. In both of these prepregs and in Example IK, the web was heated at 360°C and 200 kg/cm without adding N-methylpyrrolidone solution.
[density 0.6 s (porosity 5
2), air permeability of 0.1 seconds/room or less, pore mode of 25 μ by mercury porosimeter], prepreg obtained by impregnating with phenolic resin (Comparative Example 2) was cured to determine the dielectric breakdown voltage. The results of the measurements are shown in Figure 5.

Example 2 Polyethylene terephthalate was produced by transesterification from dimethyl terephucrate and ethylene glycol, melt-spun, stretched, crimped, opened tow, and -1 of long fibers was produced.
: ~ After adding acrylamide adhesive and making it into a non-woven fabric through a high temperature region, 240℃, 600k177cT
It was thermocompressed with I.

The fiber was 2 de, the strength was 6 kg/cd, and the elongation was 20 cm. The thickness as a non-woven fabric is 74μ, and the basis weight is G'! .

It was 7 ag/m'. Since the density of polyethylene terephthalate fiber is approximately 1.36, the amount of voids is 2.
It is 7chi. Moreover, the air permeability was 528 seconds.

The dielectric breakdown voltage of this nonwoven fabric is 10.3 kV when left as is.
In other words, it is a 4kVZ connection. This non-woven fabric was coated with 30 pieces of phenolic resin [Cemedine+1oon (registered trademark)].
The amount of impregnation when impregnated with a solution of B is 90
, D, V, was 5θkv/fight.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the specific gravity and compressive strength of the apparent Nicum core (after hardening) made from various prepregs, and Figure 2 is a graph showing the relationship between the specific gravity and compressive strength of the Nicum core (after hardening) made from various prepregs. (after) resin impregnation amount and dielectric breakdown voltage (B, D, V
, ); Figure 3 is a graph showing the strength of the prepregs described in Example 1 and Comparative Example 1;
The figure is a graph showing the strength after curing of the prepregs of Example 1 and Comparative Example 1. Figure 5 shows the resin-gold corrosion and insulation of the composite material (after curing) made from the prepregs of Example 1 and Comparative Example 1.2. It is a graph showing the relationship with breakdown voltage (B, D, V,). Patent Applicant: Teijin Ltd. Figure 1 Apparent P heavy (vcTr13) Figure 2 Epo V'4 combined immersion (system) Figure 3 71 No. 1 January Il Pigeon 1 G'/45 C (n ζ) Figure 4 Fxt-n, m day impregnation 1 leaf r%) Figure 5 Phenol city material 8ν tame Ltf%1 Procedural amendment 1. Indication of the case Patent application No. 58-154914 No. 2, name of the invention Prepreg 3, person making the amendment Relationship to the case Patent applicant Sashibe Okamoto, 1-11 Minamihonmachi, Higashi-ku, Osaka (300), Representative of Teijin Limited ( 1) The phrase "What is aromatic polyamide" on page 3, line 8 of the specification is corrected to "What is aromatic polyamide (hereinafter sometimes referred to as "7-lamid")." (2) The entire statement (Example 2) from the 4th line to the 14th line from the bottom of page 13 of the specification is deleted. that's all

Claims (1)

[Claims] 1. Consisting essentially only of heat-resistant short fibers, with a porosity of 5 to 5.
35t! Ibl air permeability 0.1-10000 seconds/xoom
, a nonwoven fabric having a mode of pore distribution of 1 to 20μ, and a prepreg impregnated with a thermosetting resin. 2. The prepreg according to claim 1, wherein the heat-resistant short fibers are short fibers made of aromatic polyamide. 3. The prepreg according to claim 1 or 2, wherein the thermosetting resin is a phenol resin, an epoxy resin, or a polyimide resin.