JPH04139231A - Resin composition containing aromatic cyanate ester, polyepoxide compound, and thermoplastic polymer, and prepreg prepared therefrom - Google Patents

Abstract

PURPOSE: To provide a curable homogenous solventless resin compsn. obtained by compounding specified polyerizable aromatic cyanate esters, an epoxy resin and a thermoplastic polymer and capable of providing a prepreg. showing good tenacity and heat/humidity performance.

CONSTITUTION: The resin compsn. contains 5.0-98 wt.%, pref., 60-90 wt.% of cyanate ester of a polycyclic crosslinked hydroxy subsid. poly-aromatic compd. (e.g.; cyanate ester of bisphenols of dicyclopentadiene) (A), 1-45 wt.%, pref., 5-32 wt.% of an epoxy resin (pref., bisphenol A epoxy resin) (B), 1-20 wt.%, pref., 15-14 wt.% of a thermoplastic polymer (e.g. polyether imide) (C) and, arbitraily, a curing accelerator (D). The composite material pref. contains 30-75 wt.% of this compsn. and a structure fiber (pref., continuous carbon fiber).

COPYRIGHT: (C)1992,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to novel thermosetting resins, and more particularly to thermosetting resins including polycyanurates, epoxy resins, and thermoplastic resins. Concerning cured resins. Still more particularly, the present invention relates to certain polymerizable cyanate ester necks,
The present invention relates to compositions comprising polymerizable epoxy compounds and thermoplastic resins, and to composite materials made therefrom.

Composite and preg materials comprising fiber reinforcement embedded in a thermoset resin matrix exhibit extraordinary toughness and excellent thermal/wet performance.

[Conventional technology]

Advanced composites are high strength, high modulus materials that
It is increasingly being used as a structural component for aircraft, automobiles, and sporting goods.

Typically, these include structural fibers, such as carbon fibers, in the form of woven fabrics or continuous filaments embedded in a thermoset resin matrix.

Most advanced composites are formed from prepreg into ready-to-form sheets of reinforcement impregnated with uncured or partially cured resins.

For most applications, prepregs are particularly useful, including their ability to lightly adhere to metal surfaces and other laminate prepregs (tackiness) and their ability to fit snugly into corners with 1/4-inch radii (covertability). It must have particularly balanced physical and chemical properties. Adhesion and coatability are particularly important for applications that coat large, complex parts such as aircraft wings and fuselages. The reactivity and therefore shelf life or shelf life of the prepreg is also important. for example,
Most aircraft applications require prepregs with low reactivity at room temperature, which retain acceptable adhesion and coverage for at least 10 days, but rapidly at elevated temperatures (i.e., 350-370'F. -4 hours).

Resin systems containing epoxide resins and aromatic amine curing agents are often used in prepregs because they have a good balance of properties.

State of the art composites made with these formulations have high compressive strength, good fatigue properties, and low shrinkage during curing. However, most epoxy formulations absorb 5-6% moisture, which causes property degradation at high temperatures and reduces the dimensional stability of the cured composite.

As a result, they are unsuitable for use at temperatures above 130° C. under moisture-saturated conditions. Most epoxy formulations used in prepregs are also brittle, so the resulting composite has low toughness and poor impact resistance.

Other curable resin systems are also known for these applications. For example, in U.S. Pat. No. 3,562.214,
Resins comprising aromatic cyanate esters and polyeboxide compounds have been disclosed.

The cyanate ester and epoxide compound are generally heated together to provide a homogeneous liquid that can be poured into a mold. The use of solutions of these components in solvents such as acetone, methyl ethyl ketone, etc. has also been demonstrated to impregnate paper and textile garments that can be used to make laminates.

No. 4,11, also comprising a cyanate ester, bismaleimide, and optionally an epoxy compound
Also useful are the compositions described in US Pat. No. 0,364; and the compositions described in US Pat. No. 4,157,360, which include crosslinked cyanate polymers and thermoplastic polymers. The latter compositions are made by removing the solvent from a solution of thermoplastic polymer and aromatic dicyanate monomer and heat curing the resulting intimate mixture above about 200°C. The composition can also be made from a melt containing the polymer and monomer by heating to 200° C. or higher to produce a partially cured or cured composition. These compositions, which typically contain equal parts by weight of thermoplastic polymer and cyanate monomer, do not have the adequate tack and covering properties commonly required for many prepreg applications.

polyphenylene ether resin, bismaleimide, and/or
or curable compositions comprising cyanate esters and epoxy compounds, along with copper-coated laminates comprising such formulations reinforced with glass fibers, are disclosed in U.S. Pat. No. 4,496,695. It has been revealed. However, polyphenylene ethers are high temperature, high melt viscosity resins and are insoluble in these liquid components.
The composition can be prepared only by first dissolving the ingredients in a suitable solvent.

[Problem to be solved by the invention]

Formulations based on bis7imides and epoxy resins are thus known and are useful for making fiber reinforced composites with good toughness and the ability to retain stiffness after exposure to hot/moist conditions. Improved formulations are needed.

[Means for Solving Problem 1IIN] The present invention relates to a novel thermosetting matrix resin formulation and a fiber-reinforced composite material containing such a formulation. More particularly, the present invention provides solvent-free curable matrix resin formulations comprising certain polymerizable cyanate esters, polymerizable epoxy compounds, and certain thermoplastic resins, as well as Fiber-reinforced composites formed from curable formulations. The curable formulation is further compounded with accelerators, fillers and fiber reinforcements.

Unreinforced cast articles made from the curable formulations of the present invention exhibit lower tensile properties and reduced stiffness compared to properties typically exhibited by more conventional cyanate esters. Therefore, cured composites comprising formulations of the present invention exhibit comparable toughness and unexpectedly improved thermal/wet properties, making them ideal for the production of tough, high-performance fiber-reinforced composites. Especially suitable! It's different. Composites comprising the thermoset matrix resin formulations of the present invention exhibit an excellent balance of toughness and heat/wet properties, and amazing bow strength. Prepregs containing these formulations have excellent and very useful processability, coverage and adhesion before curing.

Curable matrix resin formulations useful in the practice of this invention include certain esters, epoxy resins, and certain thermoplastic resins.

The cyanate ester component is a polymerizable aromatic cyanate ester compound having multiple cyanate ester groups per molecule, and can be further described as cyanate esters of polyphenols, including polymerized derivatives and oligomeric derivatives of diphenols and bisphenols. Also included are polycyanates containing aromatic groups crosslinked with cycloalkylene groups, and cyanate esters of novolak-type phenolic resins.

Cyanate esters useful in the practice of this invention include, for example, cyanated novolacs; cyanated bisphenol-terminated polycarbonates or other thermoplastic oligomers; and mixtures thereof. Also, the cyanates of poly(alkenylphenols) disclosed in U.S. Pat. No. 4,477,629, such as U.S. Pat. ) and the cyanates from the bisphenols of synchropentadiene as disclosed in GB 1.305,702. U.S. Patent No. 4,528,
Preferred are cyanate esters of polycyclic bridged hydroxy-substituted polyaromatics, including the cyanates of synchropentadiene bisphenols described in No. 366. These and a wide range of other cyanate esters are widely known in the art and many are commercially available.

Epoxy resins useful in the practice of this invention include any of a wide range of multifunctional epoxy resins that are widely known and readily available from commercial sources. Among these are polyglycidyl derivatives of phenolic compounds;
For example, Shell Chemical's Evon 828, Evon fool, Evon 1009 and Evon +031;
Dow Chemical Company's DER331, DER332, I)f
R334 and I) ER542; and Nippon Kayaku's 8REN
It is commercially available under the trade name -8nato. Other suitable epoxy resins include polyeboxides made from polyols and the like, and polyglycidyl derivatives of phenol-formaldehyde novolaks. The latter are DEN43+, DEN438, and DEN4 from Dow Chemical Company.
39, while cresol analogs are commercially available as ECN1235 from Ciba-Geigy Cohosion.
, EC)11273, and ECN1299. 5U-S is a resin based on Intelez's Bis-A. Polyglycidyl adducts of amines, amino alcohols, and polycarboxylic acids are also useful in the practice of this invention. Commercially available resins of this type include F, l
, Fryamine 135 from C. Corporation,
Fly amine! 25, and Flyamine 115; Ciba
Araldite MY- from Geigy Corporation
720, Araldite 0500, and Araldite 05
10; and P from Sherwin-Williams Co.
Includes GA-X and PGA-C.

Also suitable are epoxy-terminated thermoplastic polymers, such as the epoxy-terminated polysulfones disclosed in US Pat. No. 4,448,948.

A second group of epoxy resins useful in the practice of this invention are those made by epoxidizing dienes and polyenes. This type of resin is described in U.S. Patent No. 3.398.
It includes bis(2,3-epoxycyclopentyl) ether described in No. 102, and its reaction product with ethylene glycol.

Commercial examples of these epoxides are vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl, 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl, 3,4-epoxy -6-methylcyclohexanecarboxylate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, dibentenedioxide, and 2-(3,4-epoxycyclohexyl-5,
5-spiro-3,4-epoxy) cyclohexane metadioxane, as well as Oxilon 2001 from FMC Corp.
epoxidized polybutadiene obtained as

Other epoxy resins not specifically mentioned above may also include
It can be used as a modifier in the resin formulations of the present invention.

Preferred epoxy resins are bisphenol A epoxy resins, epoxy-novolak resins, l, 1°2.2-
Tetrakis(4-hydroxyphenyl)ethane, bisphenols such as bisphenol F, bisphenol S (4,4'-dihydroxydiphenylsulfone),
and diglycidyl ethers of tetrabromohisphenol A, and BREN-5.

In the compositions of the present invention, the cyanate ester and epoxy resin will be present in amounts based on the ratio of cyanate (-0CN) groups to epoxy groups. Generally, the ratio of cyanate groups to epoxy groups will range from l:1 to +00:l, and more preferably from 1.5:l to 50:l.

The compositions of the present invention also include a thermoplastic polymer mixed with the cyanate ester and an epoxy resin component of the curable composition. Thermoplastic polymers that can be used in the present invention have glass transition temperatures greater than about 150° C., such as U.S. Pat.
No. 5, and polyarylethers such as those described in No. 4,332,209.

In addition, polycarbonate, polyetherimide, poly(
amide-imide) thermoplastic resins and polyarylates,
Also suitable are mixtures thereof.

Preferred thermoplastics are UDELRP-1800 polysulfone and ARDELRD-100 polyarylate (manufactured from Amoco Performance Products), Lexan-105 polycarbonate, Lexan-3250 polyester carbonate, and ULTEM-1000 polyetherimide (from General Electric Company). starfish)
, and Pictrex P-200 (obtained from Imperial Chemical Industries), and Rade
l Contains RR polysulfone (manufactured from Amoco Performance Products). The above thermoplastic resin compositions are well known and described in the published art.

The resin formulation of the present invention has a composition of 50-
98% by weight, preferably 60-90% cyanate ester component; 1-45% by weight, preferably about 5-3
2% by weight of epoxy resin; and 1-20% by weight, preferably 1.5-14% by weight of thermoplastic resin.

The compositions of the present invention further comprise additional polymerizable components, including bismaleimide. Bismaleimides that can be used in the present invention as polymerizable components or in combination with cyanates in the form of BT resins are the bismaleimides of aromatic diamines, generally made from maleic anhydride and the corresponding aromatic diamines. .

Preferred bismaleimides are derived from aromatic diamines, with those derived from polynuclear aromatic diamines being most preferred. Examples of such bismaleimides are 2,2
-bis(4-aminophenoxy-4-phenyl)propane bismaleimide, 4,4'-bis(3-aminophenoxy)diphenylsulfone bismaleimide, l,4-bis(3-aminophenylisopropylidene)benzene bismaleimide, and bis(4-aminophenyl)methane bismaleimide.

Bismaleimides can be used alone or in mixtures.

Curing accelerators may also be cyanate-terminated and/or epoxy/
It can be used in the practice of this invention to facilitate cyanate co-reactions. Curing accelerators and catalysts can be conveniently used for these purposes and include phenols, tertiary amines, alcohols, salts such as LiCl, and zinc octoate,
Includes soluble transition metal complexes such as silver acetylacetonate, cobalt naphthenate, and the like. U.S. Patent Nos. 3 and 6
No. 94,410 and No. 4.528.366 describe several such catalysts and their effective levels of use.

When the composition contains bismaleimides, dicumyl peroxide, ditertiary butyl peroxide, tertiary butyl perbenzoate, and 1
, 1-bis(tert-butylperoxy)cyclohexane may also be included. Free radical inhibitors such as phenothiazines or benzoquinones are often used in resin technology to enhance storage stability, and these compounds can also be included in the compositions of the present invention.

These ingredients can be added to the composition at any desired level. When curing accelerators are used, they will be present in an amount of about 0.0015% by weight, preferably about 0.012% by weight, again based on the total composition.

The peroxide is O per 10 parts of bismaleimide in the formulation.
, Oll pb-.

The compositions of the present invention will most often be used in combination with fiber reinforcements in the manufacture of structural composites. Structural fibers that can be used to make such composites include carbon, graphite, glass, silicon carbide, and poly(
Henzothiazole), poly(henzimidazole)
, poly(henzoxazole), alumina, titania, boron, and aromatic polyamide fibers. These ams have a tensile strength greater than 100,000 psi, a tensile modulus greater than 2 million psi, and a tensile modulus greater than 200,000 psi.
It is characterized by a decomposition temperature higher than ℃. The fiber is a continuous tow (1 bundle of filaments + 000-400,000 filaments),
It can be used in the form of woven fabrics, whisker chopped fibers, or random mats. Preferred fibers are carbon fibers, aromatic polyamide fibers such as Kevlar 49 fibers (E, 1. Handcrafted from DuPont-Tonemour), silicon carbide fibers, and glass fibers. Composites are generally about 2
0 to about 80% overlap, preferably 30 to 75%! % of structural fibers.

Structural fibers will typically be interwoven with the curable resin composition of the present invention to provide a pre-impregnated reinforcement or prepreg. Prepregs can be prepared by any of several well-known techniques commonly used in the art. For example, the resin can first be coated as a thin film on release paper.

The aligned tow of carbon fibers is then pressed between two sheets of coated paper and passed through a series of heated rollers to effect infiltration of the fiber tow with resin. The resulting prepreg is then allowed to cool and taken up on a spool. A tacky, coatable prepreg is obtained with the curable composition of the present invention with a long shelf life, typically 4-6 weeks.

Composites can be prepared from prepreg by heat curing, optionally under pressure. Composites can also be cured according to the invention by wet lay-up followed by compression molding, transfer molding, or resin injection, as described in European Patent Application No. 0019149, published November 26, 1980. FA can be made from a composition of Composites using the compositions of the present invention can also be formed during a filament winding operation, where the pre-impregnated tow is wound onto a rotating removable form or mandrel, heated in a furnace or Cured in an autoclave.

In addition to structural fibers, the compositions can also contain particulate fillers such as talc, mica, carbonate, and thixotropic additives such as fumed silica. Up to half the weight of the structural fibers can be replaced in the composition by one or more such fillers.

〔Example〕

The implementation of the invention will be better understood in consideration of the following examples. These examples are provided as specific illustrations of the practice of the invention and are not intended to limit the scope of the invention in any way.

Example 1 A 3 liter flask equipped with a paddle stirrer, thermometer, temperature controller, inert gas inlet and outlet, and electric heating mantle was equipped with Ultei R100O from General Electric Co.
Powdered polyetherimide F500g obtained as polyetherimide and EpiclonR from Dainippon Ink
1500 g of bisphenol F diglycidyl ether obtained as 830 was charged. Mixture at 160℃
Heat and stir for 5 minutes, at the end of this period the polyetherimide has dissolved. A portion (300g) of the mixture is
cyanate of the phenol adduct of synchropentadiene (i.e. bisphenol of synchropentadiene) [X
Cyanate ester of polycyclic crosslinked hydroxy-substituted polyaromatic compound obtained as U7+787]
700g was added. The mixture was heated to 140° C. for 1 hour, stirred, and then drained into a pan for cooling and storage.

A thin film of resin was cast onto silicone coated with release paper, and a polyacrylonitrile-based carbon fiber (Sornel RT from Amoco Performance Products) was cast onto silicone coated with release paper.
Typical properties were used to make unidirectional pre-reg tabs with tensile strength of 650 kpsi; Young's modulus of 35 mpsi; density of 1.78 g/cc; and number of filaments per tow of 12,000).

The finished prepreg cheese contained approximately 35% resin by weight, had a fiber areal weight of 146 g/m2, and was 12 inches wide.

[(±30), 901. A 10-layer laminate (6" x 12") with a brining direction of 1 was laminated with this prepreg and cured in an autoclave as follows. The laminate was cured in a forced air oven at 4450F for 4 hours. Six l″xlO″ test specimens cut from the laminate were tested for edge delamination strength (EDS) measurements. EDS
The test was conducted in the aerospace industry to assess the toughness of composite materials. The test procedure followed is that described in SAMPE Journal Vol. 18 No. 4, July/August 1982, page 8. The physical properties of the laminated wood and the base material plum fat are as follows:
They are summarized in Table 1.

Control A Following the procedure of Example 1, an additional amount of polyetherimide/epoxy mixture was obtained. Next is the old tea+/Epi
830 formulation into a 2 liter flask, followed by RDX803 from Hytic Polymers.
700 g of 52 bisphenol A dicyanate was charged. The mixture was heated to 140° C. for 1 hour and stirred.

A unidirectional prepreg cheese was made according to the procedure of Example 10. The final prepreg with a fiber side 1F 35% resin content by weight of 146 g/m2 and a 12 inch diameter was formed into a test laminate as in Example 1.

To measure the thermal/wet performance of the composites, prepreg chives were stacked into 8 layers of 6 II x I 2 I+ laminates with a (+45)2° configuration. Harden the laminate as above,
Post-cured and then cut into l II xl Q II strips and measured for retention of high temperature properties under humid conditions. The strips were soaked in water at 1600F for two weeks and then placed in an Instron testing machine to measure stiffness. The tensile stiffness of the moisture conditioned specimens was measured at room temperature and 3250F after heating to this temperature for less than 1 minute.

The molten resin was degassed in a vacuum furnace at 130°C for 10 minutes, then the degassed resin was poured into a glass mold with a 1/8"x8"xlO" cavity, and the casting material was heated as follows. hand,
Unreinforced castings of the resin of Example 1 and the resin of Control A were made.

75'F → 350'F, 3'F/min; held for 4 hours;
350'F → 445'F, 3°F 1 minute; held for 4 hours;
Cool at 10'F/min.

A Type 1 dog specimen was cut from the cast material for testing.

The properties of the composite materials and unreinforced cast material specimens of Example 1 and Control A are summarized in Table 1.

Table 1 Examples IA Component cyanate (wt%) 63.6 66.0 Epoxy resin (wt%) 27.6 28.3 Polyetherimide 6.8 5.7 (wt%) Casting material properties Tensile strength (kpsi ) 6.7 9.
8 Tensile Modulus (kpsi) 406 43
6 Elongation rate (%) 2.7 1.7
Composite material properties EDS (kps i) 32.6
32.1Mod, Rtn, @325'F(ri)
54.0 32.6 Note: Tensile properties are ASTM
Measured according to D-638.

EDS = edge delamination strength; Mod, Rtn, =
Retention of room temperature stiffness at 3250F after 2 weeks immersion in water at 160'F; see text. Polyether imi F' = U
tem1000 polyetherimide (manufactured from General Electric Co.) Comparing the properties of Example 1 with those of Control A shows that when the resin formulation of the present invention is cast and cured without reinforcement, it It can be seen that it exhibits somewhat lower tensile properties than comparable formulations based on his-cyanate resins. It will also be observed that the EDS properties of the composites of the present invention are not significantly different from those of control composites based on more conventional bis-maleimide formulations.

It is therefore surprising that fiber-reinforced composites made from such formulations exhibit significantly improved thermal/wetting properties and an improved ability to retain stiffness at elevated temperatures, especially after water immersion. . It is therefore very surprising that fiber-reinforced composites based on such resin formulations exhibit comparable toughness to composites based on more conventional cyanate resin formulations, as shown in Table 1. Targeted and unexpected.

Thus, the present invention provides polymerizable cyanate esters, preferably cyanate esters of polycyclic crosslinked hydroxy-substituted polyaromatic compounds such as bisphenols of synchropentadiene, polymerizable epoxy resins, and It can be seen that there is a homogeneous, solvent-free, curable matrix resin formulation comprising a plastic resin, and a fiber-reinforced composite comprising such formulation. The matrix resin formulation may further include one or more additional curable ingredients, including bismaleimides, cure accelerators, fillers, fiber reinforcements, heat and light stabilizers, pigments, dyes, etc. Can be included. While the compositions of the present invention can be used as matrix resins for composites, as high temperature coatings, and as adhesives, fiber-reinforced composites can be used in orthopedics, floor panels, flap drive shafts, bumpers, and Suitable for use as springs and in the construction of pressure vessels, tanks and pipes. They are also suitable for sports equipment such as golf club shafts, tennis rackets, and fishing rods. Furthermore, additions and changes may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (1)

Claims: 1. A curable compound comprising (a) a cyanate ester of a polycyclic crosslinked hydroxy-substituted polyaromatic compound, (b) an epoxy resin, and (c) a thermoplastic polymer. A homogeneous solvent-free resin composition. 2. from about 50 to about 98% by weight of a polycyclic crosslinked hydroxy-substituted polyaromatic cyanate ester; from about 1 to about 45% by weight of an epoxy resin; and from about 1 to about 20% by weight of a thermoplastic polymer. The resin composition according to claim 1, comprising: 3. The composition according to claim 1 or 2, further comprising structural fibers. 4. The composition of claim 3, wherein the structural fibers are continuous carbon fibers. 5. The composition according to claim 2 or 4, wherein the cyanate ester is a cyanate ester of bisphenol of synchropentadiene. 6. The resin according to claim 2 or 4, wherein the thermoplastic polymer is polyetherimide. 7. The resin according to claim 1 or 2, further comprising a curing accelerator. 8. The composition of claim 2 or 4 comprising from about 60 to about 90% by weight of the cyanate ester described above. 9. The composition of claim 2 or 4, comprising from about 5 to about 32% by weight of the epoxy resin described above. 5. A composition according to claim 4, comprising from 10.30 to 75% by weight of continuous fibers as described above.