JPS636162A - Multi-electrolyte shearing treatment of carbon fiber - Google Patents

Abstract

Carbon fibers can be surface treated to improve interfacial bonding in a composition comprising said fibers reinforcing a bis-maleimide matrix resin, comprising the steps of: moving said fiber, as anode, through a first aqueous electrolytic bath containing an ionized acid base or neutral salt, followed by moving said fiber, as anode, through a second electrolytic bath containing an ammonium salt, said bath having a pH of at least about 8. Composites comprising the carbon fibers so treated in a bis-maleimide matrix resin have good edge delamination strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to electrolytically treating the surface of carbon fibers to improve their mechanical properties, particularly when bonding the fibers with a resin matrix to produce composites. Concerning how to.

The present invention further relates to the improved carbon fibers themselves and composites comprising the improved carbon fibers in a bismaleimide matrix resin.

[Conventional technology]

It is known to electrolytically treat carbon fibers to improve the adhesion between the fibers and the matrix resin when making composite materials. The strength properties in composite materials and their durability, especially in the environment, depend on the interfacial bonding of the composite, ie the bond strength between the carbon fibers and the resin matrix.

The development of various methods for increasing interfacial bonding is thus a major objective of composites research, as evidenced by the prior art.

Ray et al., U.S. Pat. No. 3,671,411, discloses electrolytically reacting carbon or graphite fibers in an aqueous solution of an electrolyte so that negative ions are attracted to the surface of the fibers, which act as anodes, resulting in the formation of 'a-fibers. It is disclosed that the surface is modified.

The patentee claims that the resulting plastic-to-resin bond is improved, and in many cases the shear strength is more than double that obtained without this special pretreatment with little or no loss of tensile strength. states that it will increase.

Saito et al., U.S. Pat. No. 4,401,533, teaches passing a current through a fiber in an aqueous sulfate solution at a specific range of current density, the product of current density, voltage, and processing time, and using carbon as the negative anode. Carbon fibers are disclosed that have been electrolytically surface treated by continuously moving the fibers in an aqueous electrolytic solution. The patentees state that their method produces carbon fibers with good resin adhesion, high tensile strength, and high heat-oxidation resistance.

U.S. Patent No. 3,832,297 by Ball Jr.
No. 1 discloses an electrolytic method for the surface treatment of graphite fibers, in which an improvement lies in the use of organic and organic ammonium compounds dissolved in water, the compounds being heated at temperatures below about 250°C. Upon heating, it decomposes substantially completely into gaseous products.

Exemplary ammonium compounds are ammonium hydroxide, ammonium carbonate, ammonium bicarbonate, ammonium carbamate, ammonium benzoate, ammonium dithionate, ammonium hydrosulfide,
It states that it includes ammonium acid, ammonium thiosulfate, and ammonium tartrate.

[Problem that the invention seeks to solve]

No prior art known to the inventors discloses electrolytically treating carbon fibers in special continuous electrolytic baths. Provided are carbon fibers useful for producing composites with high strength (EDS).

EDS is a measure of toughness in carbon fiber composites and indicates the tendency of cracks around rivet holes in the composite.
The test is well known to those skilled in the art.

[Means to solve the problem]

The present invention provides a method for surface treating carbon fibers to improve the mechanical properties of composites containing said fibers reinforcing bismaleimide matrix resins, the steps comprising:
Applicable! a! The fiber is moved as an anode through a first aqueous electrolytic bath containing an ionized acid, base or neutral salt, and then moved through a second aqueous electrolytic bath containing an ammonium salt, with the fiber as an anode. Both consist of passing through a bath having a pH of about 8.

The term "carbon'a fiber" as used herein refers to carbon and graphite)! It refers to the entirety of li and includes fibers produced by heating fibrous polymeric materials such as polyacrylonitrile, polyvinyl alcohol, pitch, natural and regenerated cellulose, etc. to carbonization or graphitization temperatures.

- In general, latin is made up of individual filaments that are thin and do not exhibit any real mechanical irregularities, and are conveniently handled in multifilament bundles, known to those skilled in the art as tows. Other physical arrangements of fibers are also possible, such as woven fabrics or unrimmed mats.

The electrolyte used in the first aqueous electrolytic bath (also referred to herein as the acid bag bath) electrolytically generates oxygen at the anode, i.e., the surface of the carbon fibers being treated, so that oxygen functional groups are distributed on the surface of the fibers. It is preferably an aqueous solution of mineral acids and bases, such as phosphoric acid, nitric acid, sulfuric acid and alkali metal hydroxides, including sodium and potassium hydroxides, containing any electrolytes as may occur. More preferred are neutral salts (ie, those that produce a pH between about 4 and about 8 when dissolved in water) such as sodium sulfate, lithium sulfate, sodium perchlorate, and sodium tetrafluoroboronate. In practical applications - typically 0.05 to 20
% by weight, preferably from 1 to 10% by weight
A concentration of electrolyte within the range of is preferred.

In the second electrolytic bath (also referred to herein as an ammonium bath), any ammonium salt that dissolves in water and produces a pH of at least 8 is used. Preferred are ammonium hydroxide and ammonium bicarbonate. The ammonium compound is believed to improve the properties of the composite by modifying it with carbon mII backside-NH2 functionality. The concentration of ammonium salt can be any desired concentration sufficient to impart -NH2 functionality to the surface of the carbonate fibers so that the mechanical properties in the composite are improved, as measured by, for example, edge delamination strength. . - Typically such a concentration is about 0.02M (
1 degree) to about 5M, preferably about 0.05M to about 3M.

Any of the neutral salts or alkali metal hydroxide supplementary electrolytes mentioned as preferred for use in the oxygen bath may be used to increase the conductivity in the ammonium bath. - Generally the concentration of such supplementary electrolytes is from about 0.01 M to about 0.5
It is within the range of M.

The voltage is not narrowly critical - generally the current density is about 0.5 to 5 milliamps per square meter of fiber surface area (
mA/cm2). - Generally the voltage used in each province is in the range between about 5 and 80 volts.

The bath temperature is not narrowly critical - generally within the range of about 5°C to 50°C, with ambient (room) temperatures or below being most preferably used.

The voltage, current density, and residence time are such that the fiber has a total charge of about 4 to 100 coulombs/g, preferably about 7 to about 2
It is advantageous to operate so as to receive 0 coulombs/g.

Using the typical charge and voltage ranges discussed above, a residence time of about 0.05 to about 1 minute is generally sufficient to receive a charge within these ranges. Line speeds up to about 40 feet/minute are quite possible, depending on the actual length of the bath feeding the tow, which is typically between about 1 and about 15 feet in length.

The present invention provides increased mechanical properties of thermoset resin composites over those attributable to either of the two savings or the additive contribution of their baths. This result is surprising. This is because carbon fibers electrolytically treated in successive baths of the opposite order to the successive swamps specified in the claims result in no improvement or, in some cases, less improvement than would be obtained using oxygen baths alone. Sometimes even.

Preferred thermosetting bismaleimide resins used in the present invention are those widely known to those skilled in the art and are generally N, N'
- produced by reacting bismaleimides with reactive comonomers copolymerizable with them. The general structural formula of preferred bismaleimides is: where Y is a divalent group of at least 2 carbon atoms, preferably 2 to 6 carbon atoms, and contains a carbon-carbon double bond. shows. Y is, for example, the formula R2.

A preferred structural formula of Y is: It is.

Y is obtained, for example, from an acid or anhydride such as maleic acid, citraconic acid or tetrahydrophthalic acid.

Z is a divalent group which can be the residue of a diamine containing at least 2 carbon atoms and generally no more than about 20 carbon atoms. By residue we refer to the part of the diamine which of course excludes the two 7-mino groups. Z is, for example, fullkylene of 2 to 20 carbon atoms; cycloalkylene of 5 to 6 carbon atoms; heterocycle of 4 to 5 carbon atoms and at least one nitrogen, sulfur or oxygen atom; or directly to each other by a carbon-carbon bond or by a divalent bonding group such as -0-1-S-fulkylene of 1 to 3 carbon atoms, or of the formula, where R1 is alkyl of 1 to 5 carbon atoms,
Among groups containing more than one R1, there can be at least two mono- or dicarbocyclic aromatic or cycloalkylene groups bonded through [which need not be the same].

Preferred NN'-bismaleimides include 1,2-bismaleimidoethane, 1,6-bismaleimidehexane, 1
, 12-bismaleimidododecane, 1,6-bismaleimido-(2,2,4-trimethyl)hexane, 1,3
-Bismaleimidobenzene 1.4-Bismaleimidobenzene, 4.4'-Bismaleimidodiphenylmethane, 2
．． 4-bismaleimidotoluene, 2.6-bismaleimidotoluene, 3,3'-bismaleimidodiphenylsulfone 4.4'-bismaleimidodiphenylsulfone, 4
．． 4'-bismaleimidiphenyl ether, 4.4'
-bismaleimidodicyclohexylmethane 4,4'-bismaleimidodiphenylcyclohexane, 4,4'-bismaleimidodiphenylsulfite, N,N'-m-
Xylylene bismaleimide, N,N'-p-xylylene bismaleimide, N,N'-m-phenylene bis-
Citraconimide, N.

N''-4,4'-diphenylenemethane bis-citraconimide, and mixtures thereof. The above compounds are described, for example, in U.S. Pat.
No. 11,861 and U.S. Pat. No. 4,35 to Street et al.
No. 1.932. Other N.

N'-bismaleimides and their preparation are described in U.S. Pat.
No. 3,839,358 and No. 4,269,966, the disclosures of which are expressly incorporated by reference herein.

Additionally, preferred for use here is the structural formula It is an ether bis-maleimide having the following.

[In the formula, R2, R3, R4 and R5 are each hydrogen, 1 to 6
lower alkyl having 1 to 6 carbon atoms, chlorine or bromine, R6 and R7 are each hydrogen, methyl, ethyl, trifluoromethyl or trichloromethyl, and D is 2 is an ethylenically unsaturated divalent group containing 24 carbon atoms. Particularly preferred are the following ether bismaleimides, which can be prepared by reacting 2°2-bis[4-(4-aminophenoxy)phenyl]propane and maleic anhydride in acetone.

These ether bis-maleimides include the preferred compounds and their preparation is described by Nijikawa et al., U.S. Pat.
No. 460,783, incorporated herein by reference.

Preferred bis-maleimides are (a) 4,4'-bismaleimidodiphenylmethane, (b) 1,6-bismaleimido-(2,2,4-)limethyl)hexane, (c) (
Contains a eutectic mixture of a) and (b) with 2,4-bismaleimidotoluene. Application No. 564, 40, filed December 22, 1983, which was also passed to the applicant.
Any of the bis-maleimides disclosed in No. 0, herein incorporated by reference, may also be used in the present invention.

and bis-maleimides to produce sumaleimide resins, preferred liquid co-reactants for use in the present invention are 0,0. - Diallylbisphenol A, N-vinyl-2-pyrrolidinone, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, triallyl isocyanate Divinylbenzene, diallyl phthalate, triallyl trimellitate, divinylbenzene, dicyclopentadienyl diethyl acrylate, dicyclopentadienyloxyethyl acrylate, vinylcyclohexene monoepoxide, 1,4-butanediol divinyl ether, 1
, 4-dihydroxy-2-butene, styrene, flufluoromethylstyrene, lyaa-nutyrene, p-phenylstyrene, t-butylstyrene, phenyl vinyl ether, Im! Including Japanese polyester neck, vinyl ester resin, etc.

Preferred liquid coreactants include o,o'-diallylbisphenol A, N-vinyl-2-pyrrolidone, triallyl isocyanurate, divinylbenzene, and ethylene glycol dimethacrylate.

Other liquid co-reactants include epoxy resins containing one or more epoxy groups having the following structural formula: The epoxy group can be a terminal epoxy group or an internal epoxy group. There are two types of epoxides - products obtained from the epoxidation of polyglycidyl compounds or dienes or polyenes. The polyglycidyl compound contains a plurality of 1,2-epoxide groups obtained by reaction of a polyfunctional active hydrogen-containing compound with excess shrimp halohydrin under basic conditions. When the active hydrogen compound is a polyhydric alcohol or a phenol, the resulting epoxide tree N contains glycidyl ether groups; a preferred group of polyglycidyl compounds is 2,2-bis(4-hydroxyphenyl)propane (which is also bisphenol). It is produced through a condensation reaction with (also known as A) and has the structure shown in I.

■ [In the formula, n has a value of about 0 to about 15. These epoxides are bisphenol-A epoxy resins. They include 5 e.g. Shell Chemical Corporation's Epon 828, Epon 1001, and Epon 1009 and Dow Chemical Corporation's DER331 and D
It is commercially available under trade names such as ER334. The most preferred bisphenol A epoxy resin is
The n value has a value between O and 10.

4.4''-dihydroxydiphenylmethane, 4゜4'-
Dihydroxydiphenyl sulfone, 4,4'-bisphenol, 4-4'-dihydroxydiphenyl sulfide, phenolphthalein, resorcinol, 4,2'
- Polyepoxides that are polyglycidyl ethers such as bisphenol or tris(4-hydroxyphenyl)methane are useful in the present invention. In addition, Epon 1031 (1,1 from Shell Chemical Company)
2.2-tetrakis(hydroxyphenyl)ethanetetraglycidyl derivative), and Avogen 101 (a methylolated bisphenol A resin from Schief 7-Chemical Corporation) may also be used. D, E, R
Halogenated polyglycidyl compound necks such as 542 (brominated bisphenol A epoxy resin from Dow Chemical Company) are also useful. Other preferred epoxy resins include polyepoxides made from polyols such as pentaerythritol, glycerol, butanediol or trimethylolpropane and shrimp halohydrin.

■ Phenol-formaldehyde tuborax as shown in the formula [wherein n is 0.1 to 8] and resol-formaldehyde tuborax as shown in the formula (2) [wherein n is 0.1 to 8]. Glycidyl derivatives may also be used.

III R CH3 The former is manufactured by Dow Chemical Company, E, N431
, D, E, N438 and E, N485. The latter is for example ECN 1235,
ECN1273 and ECN1299 (obtained from Civer Gaiki Corporation, Aldsley, New York). Pond's epoxidized tuborax, such as 5U-8 (Celanese Polymers Specialty Company, Royceville, Ky.), is also preferred.

In addition to phenols and alcohols, other polyfunctional active hydrogen compounds can be used to prepare polyglycidyl adducts useful as reactive comonomers of the present invention. These include amines, amino alcohols and polycarboxylic acids.

Adducts obtained from amines include N,N-diglycidylaniline, N,N-diglycidyltoluidine, N,N
, N',N'-tetraglycidylxylylenediamine (i.e. IV), N,N,N',N'-tetraglycidyl-bis(methylamino)cyclohexane (
i.e. V), N, N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane (i.e. Vl
), N, N, N', N'-tetraglycidyl = 3.3
'-diaminodiphenylsulfone and N.

N'-dimethyl-N,N'-diglycidyl-4,4'-
Contains diaminodiphenylmethane. Commercially available resins of this type are Glyamine 135 and Glyamine 12.
5 (F, 1. Obtained from C Corporation, Sun Francisco, Calif.), Araldite MY-
720 (obtained from Ciba-Geigi Corporation) and PGA-X and PGA-C (obtained from Sherwin-Williams Corporation, Chicago, IL).

(2) Preferred polyglycidyl adducts derived from amino alcohols are O,N, available as Araldite 0500 or Araldite 0510 (obtained from Chiba Gaiki Corporation).

N-triglycidyl-4-7 minophenol and 0,
N, N-)liglycidyl-3-7 minophenol (F, 1. From C Corporation, Glyamine 115
(including those that can be done manually).

Also preferred for use as reactive comonomers are glycidyl esters of carboxylic acids. Such glycidyl esters include, for example, diglycidyl phthalate, diglycidyl terephthalate, diglycidyl isophthalate, and diglycidyl adipate, and also triglycidyl cyanurates and isocyanurates, N,N-diglycidyl oxamides. ,XB279
N,N'-diglycidyl derivatives of hydantoins such as No. 3 (obtained from Chibagaiki Corporation);
Diglycidyl esters of alicyclic dicarboxylic acids and polyepoxides such as polyglycidyl thioethers of polythiols may also be used.

Other reactive epoxy-containing materials are copolymers of acrylic esters of glycidol, such as glycidyl acrylate and glycidyl methacrylate with one or more copolymerizable vinyl compounds. Examples of such copolymers are 1:1 styrene-glycidyl methacrylate, 1:1 methyl methacrylate-glycidyl acrylate and 62.5:24:13.5 methyl methacrylate:ethyl acrylate:glycidyl methacrylate.

Epoxy functional groups, such as 2,4,6,8.10-pentakis[3-(2,3-epoxypropoxy)propyl]-2,4,6,8,10-pentamethyl-cyclopentasiloxane and 1.3 Silicone resins containing -bis-(3-hydroxypropyl)tetramethyldisiloxane may also be used.

The second group of epoxy resins is produced by epoxidation of dienes or polyenes. This type of resin is bis(2,3-epoxycyclobentyl)ether, ■, U.S. Pat.
The reaction product of ■ and ethylene glycol described in No. 98,102, δ(6)-glycidyl-2-(1,2-
epoxyethyl)bicyclo[2,2,1]hebutane, ■
, and dicyclobentadiene dieboxide.

Commercial examples of these epoxides include vinyl cyclohexene dioxide, such as rERL-4206 (obtained from Union Carbide Corporation); 3.
4-epoxycyclohexylmethyl 3.4-epoxycyclohexanecarboxylate e.g. rERL-42
21J (obtained from Union Carbide Corporation), 3°4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexane carboxylate, such as rERL-4201J (obtained from Union Carbide Corporation), bis( 3,4-Epoxy-6-methylcyclohexylmethyl)adipate, ηRiba rERL-4289J (
obtained from Union Carbide Corporation),
dipentene dioxide, e.g. rERL-4269J
(obtained from Union Carbide Corporation), 2- (3°4-epoxycyclohexyl-5,
5-spiro-3,4-epoxy) cyclohexane metadioxane, e.g. rERL-4234J (obtained from Union Carbide Co., Ltd.) and epoxidized polybutadiene, e.g.
(obtained from FMC Corporation).

Other preferred reactive cycloaliphatic epoxides are disclosed in U.S. Pat.
, 750,395, 2,890,194 and 3,31
No. 8,822, incorporated herein by reference, including:

Other preferred epoxides include:

[In the formula, n is 1 to 4, m is (5-n), and R
9 is H, halogen or CI to C4 alkyl].

Preferred epoxy resins include bis(2,3-epoxycyclopentyl)ether, N,N,N',N'-
Tetraglycidylxylylenediamine, N,N.

N',N'-tetraglycidylmethylene dianiline 0,N,N-)liglycidyl-4-7 minophenol,
and O,N,N-)liglycidyl-3-aminophenol.

When epoxy resins are used, it is desirable to add aromatic diamines to the formulation. The diamine should have a low level of reactivity with the epoxy resin and the sumaleimide at room temperature. Preferred polyamine curing agents used in epoxy resin systems include 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 3,4'-diaminobenzophenone, m-phenylenediamine, 4,4''-methylene diamine, From 0.3 to 2.0, preferably from 0.5 to 1.5 equivalents of the -NH stoichiometry may be used per equivalent of 1,2-epoxide groups, including aniline, diethylenetriamine, and the like.

The epoxy resin system may additionally contain accelerators to increase the curing rate of the epoxy+amine reaction. Accelerators that may be used here include Lewis acid, amine complexes such as BF3, monoethylamine, BF3-piperidine,
BF3. Amines such as 2-methylimidazole, imidazole, and derivatives thereof such as 4-ethyl-2-
Methylimidazole, 1-methylimidazole, 2-methylimidazole, etc., N,N-dimethylbenzylamine, acid salts of tertiary amines, such as p-toluenesulfonic acid, imidazole complexes, salts of trifluoromethanesulfonic acid, such as FC -520 (obtained from 3M Company), organophosphonium halides, and dicyandiamide. If used, the accelerator is 1 to 6% by weight based on the weight of the epoxy component.

The thermosetting resin may also include compounds having one or more cyanate ester groups.

Cyanate ester means a compound having at least one cyanate group in its molecule.

The cyanate ester has the formula RIG -(0-CE-N)
Express it in g. In the formula, R1[+ is a residue derived from an aromatic hydrocarbon selected from the group consisting of benzene, biphenyl and naphthalene, or at least two benzene rings are the following groups R1+ C- I2 [In the formula 8 The mouth and R12 are the same or different,
Residues derived from compounds bonded to each other by bridging members selected from hydrogen atoms or alkyl groups containing 1 to 4 carbon atoms, -0-1-CH2OCHz-1-5-1, respectively. the aromatic residue R1 [l is optionally substituted by a substituent selected from an alkyl group containing 1 to 4 carbon atoms, an alkoxy group containing 1 to 4 carbon atoms, a group consisting of chlorine or bromine; g is an integer from 1 to 5, and the cyanate group is always bonded directly to the aromatic nucleus.

Examples of cyanate esters are cyanatebenzene, dicyanatebenzene, 1,3.5-)dicyanatebenzene, 1.3-1.4-1.6-1.8-2.6- or
2,7-cyanatobenzene, 1.3.6-dolysinatenaphthalene, 4,4'-dicyanatebiphenyl,
Bis(4-cyanatophenyl)methane, 2,2-bis(4-cyanatophenyl)propane, 2,2-bis(
3,5-dichloro-4-cyanatophenyl)propane, 2,2-bis(3,5-dibromo-4-dicyanatophenyl)propane, bis(4-cyanatophenyl)
Ether, bis(4-cyanatophenyl)thioether, bis(4-cyanatophenyl)sulfone, bis(
4-cyanatophenyl) phosphite, bis(4-cyanatophenyl) phosphate, bis(3-chloro-
cyanated novolaks derived from 4-cyanatophenyl)methane, novolaks, cyanated bisphenol-type polycarbonate oligomers derived from bisphenol-type polycarbonate oligomers, and mixtures thereof.

Mixtures of bismaleimides, epoxy resin systems, and compounds having one or more cyanate ester groups may be used in the present invention.

Preferred mixtures are (m) bismaleimide resin/epoxy resin mixture (II) epoxy resin/cyanate ester compounds, and (i) bismaleimide resin/cyanate ester compounds.

The composites of the invention may optionally contain small amounts of thermoplastic polymers. These substances have a beneficial effect on the viscosity and film strength properties of the bismaleimide/reactive comonomer mixture.

Thermoplastic polymers used in the present invention include polyaryl ethers of formula (2) described in U.S. Pat. Nos. 4,108.837 and 4,175,175.

-(0-RI3-0-RI4)n-IX [where RI3 is bisphenol A, hydroquinone, resorcinol,
4.4-bisphenol, 4゜4'-dihydroxydiphenylsulfone, 4,4'-dihydroxy-3,3'',
5.5'-tetramethyldiphenyl sulfide, 4
, 4'-dihydroxy-3', 3', 5.5'-tetramethyldiphenylsulfone, etc., and RI4 is 4,4'-dichlorodiphenylsulfone, 4,4'-difluorobenzophenone. It is a residue of a benzenoid compound that easily undergoes nucleophilic aromatic substitution reactions such as

The average value of n is about 8 to about 120.

Other preferred boaryaryl ethers are disclosed in U.S. Pat.
332, No. 209.

Also preferred are formula % formula % polyhydroxy ethers. In the formula, RI5 is an alicyclic or aromatic divalent hydrocarbon group, the average value of n is between about 8 and about 300, bisphenol A, tetramethylbisphenol A, 4゜4゛-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3',
5.5'Tetramethyldiphenylsulfone, hydroquinone, resorcinol, 4,4'-dihydroxy-3
, 3', 5.5'-tetramethyldiphenyl sulfite, 4,4' bisphenol, 4,4'-dihydroxydiphenyl sulfite, phenolphthalein,
2.2.4.

It is a polycarbonate based on 4-tetramethyl-1,3-cyclobutanediol or the like. Other preferred thermoplastic polymers are poly(ε-caprolactone), polybutadiene, polybutadiene/acrylonitrile copolymers including those which may optionally contain amine carboxyl, hydroxy, or -9H groups, e.g. Polyesters such as poly(butylene terephthalate), poly(ethylene terephthalate), polyetherimide, such as urthene resin (obtained from General Electric Company), acrylonitrile/butadiene/styrene copolymers, nylon 6, nylon 6.6, Nylon 6.12, and polyamides such as Trogamide T (obtained from Dynamite Nobel Corporation), Tetron poly(amideimide) (obtained from Amco Chemical Corporation, Napierville, IL)
such as poly(amideimide), polyolefins, polyethylene oxide, poly(butyl methacrylate)
,? Polystyrene with increased tI impact resistance, sulfonated polyethylene, bisphenol A, isophthalic acid, and
It includes polyarylate derived from tetramethyl acid, poly(2,6-dimethylphenylene oxide), polyvinyl chloride and copolymers thereof, polyacetal, polyphenylene sulfite, and the like.

Poly(vinyl acetate) and copolymers of vinyl acetate and vinyl and acrylic monomers may also be used. Low extrusion additive thermoplastic polymers such as LP-40A may also be used.

The composition of the bismaleimide thermoset resin is from about 1 to about 99%
% by weight, preferably 20-98% by weight of bismaleimide, 1 to about 60% by weight, preferably 3 to 40% by weight of liquid co-reactant or one or more 7 as described above.
The mixture of co-reactants consisting of molecules with amino, epoxy, or cyanate groups should contain from 1 to about 40% by weight, preferably from 2 to 30% by weight of other additives such as thermoplastic polymers. be.

The amount of carbon fiber in the composite is between about 10 and about 90% by weight, preferably between about 20 and about 85% by weight.

Additional ingredients in the formulation include initiators for vinyl polymerization, such as di-butyl oxide, dicumyl peroxide, 1.1
-bis-t-butylperoxycyclohexane, azobisisobutyronitrile, and the like. The initiator consists of 3% by weight of O of the total formulation.

Inhibitors of vinyl polymerization may also be used. They include hydroquinone, t-butylhydroquinone, pentoquinone, f-methoxyphenol and 4-nitro-m-cresol. The inhibitor is present in an amount of 2% by weight of O of the total formulation.

By reaction of a preferred reactive comonomer with one of the above-mentioned normalimides or metals, a prebragable matrix resin can be obtained, and the surface-treated carbon ml according to the invention can be obtained. It can be combined with I to create a pre-impregnated reinforcement.

Pre-impregnated reinforcement can be prepared using several techniques known to those skilled in the art,
For example, it can be manufactured by wet winding or hot melting. One method of making impregnated tow or non-directional tape is to pass the fibers through a resin mixture bath. A non-reactive, volatile solvent, such as methyl ethyl ketone, may optionally be included in the resin bath to reduce viscosity.

After impregnation, the reinforcement is passed through a die to remove excess resin and
It is sandwiched between layers of release paper and passed through a series of heated rollers, cooled and wound onto a spool. It can be used within a few days or can be stored O'F for several months.

Composites can be made by curing the pre-impregnated reinforcement using heat and optionally also pressure. Vacuum bag/autoclave curing works well for these formulations. Laminates can also be made by wet laying and then compression molding, resin transfer molding, or resin injection molding. These molding methods are
It is described in European Patent Application No. 0019149, published on November 26, 1980. Typical curing temperatures are 100"F to 500'F, preferably 1800
F to 450'F.

The composite of the present invention can be used as aircraft parts such as wing plates, fairings of wing cascade bodies, floor panels, flaps, radomes, etc., as automobile parts such as drive shafts, bumpers, and springs, and as pressure vessels, tanks, and pipes. It can be done. They are also suitable as protective armor for military vehicles and for sports equipment applications such as golf shafts, tennis rackets, and fishing rods.

In addition to the structural fibers, the formulations may also contain particulate fillers such as talc, mica, calcium carbonate, aluminum trihydrate glass microhollow spheres, phenolic thermospheres, and carbon black. good. Up to half the weight of the structural fibers in the formulation can be replaced by fillers. Thixotropic agents such as fumed silica may also be used.

Example 1 An unsheared carbon fiber sample without commercially available manual sizing as a tow having a trade designation of T-300 from Union Carbide Corporation was processed in a bath. The fibers other than the control fibers were electrolytically treated in a nitric acid bath (a degree 0.5M) and/or an ammonium hydroxide bath (VI4 degree 2.65M). The degree of shearing treatment is the ES of sizeless fibers.
C4, and 54 parts by weight of methylene dianiline bismaleimide and 0. A composite EDS test was performed using a bismaleimide matrix resin consisting of a mixture of 46 parts by weight of o-diallylbisphenol A. The polarity of each province was the same. The composite was made by layering 10FjfJj prepregs made by hot melt method. 4 near the center
The two layers are T with a fiber areal weight of approximately 145 g/m2.
-300 carbon'a fibers were included. The other six external N(
(3 layers on each side of the 4 central layers) is approximately 136g/m2
All composites were autoclave cured and resin bleed made with T-40 carbon fiber (hand available from Union Carbide Corporation) with a fiber areal weight of
Gave 0%.

The results of ESCA and EDS are shown in Table 1 along with line speed and current saving values. The mist + labeled electrolyte indicates two separate baths.

Processing Line current ESCA EDS (Si) level Speed Nene electrolyte (Ri-
0shi (foot (7: / GM
Manufacture Kenjirai-”Sagi〕 −αi〕 −Σtun9
No-ma-L - --4,22,3
21,5+8.7HNO39,850,210,9+,
9 40.1 33.3N840H16,420,3
6,83,840,138,6HNO34,9100,
28,21,8+N)+40H8,240,37,24
,644,442,lHNO39,850,212,0
! ,0+NH4OH16,420,37,87,647
,740,0 Tree The polarity of the electrodes in the bath is shown.

Wooden plants dried overnight at 180°F.

Those skilled in the art will readily appreciate that many modifications may be made in the exemplary implementation U described above without substantially altering the novelty and advantages of the present invention.

Claims (1)

[Claims] 1. (a) moving the carbon fiber as an anode through a first electrolytic bath consisting of an aqueous solution of an oxidizing agent; and (b) moving the carbon fiber as an anode through a second electrolytic bath consisting of an aqueous solution of an ammonium compound. A method of surface treating carbon fibers comprising passing the carbon fibers through an electrolytic bath having a pH of at least about 8. 2. The method according to claim 1, wherein the oxidizing agent is an oxyacid. 3. The method according to claim 1, wherein the oxidizing agent is an oxyacid selected from the group consisting of nitric acid, sulfuric acid and phosphoric acid. 4. The method of claim 1, wherein the oxidizing agent is present in the range of about 0.5 to about 20% by weight. 5. The method of claim 1, wherein the oxidizing agent is present in the range of about 1 to about 10% by weight. 6. The method according to claim 1, wherein the ammonium compound is ammonium hydroxide. 7. The method of claim 1, wherein the concentration of the ammonium compound is from about 0.02M to about 5M. 8. (a) moving the carbon fiber as an anode through a first electrolytic bath consisting of an aqueous solution of about 0.5 to about 20 weight percent nitric acid; 2. The method of claim 1 for surface treating carbon fibers comprising the step of passing through a second electrolytic bath consisting of an approximately 5M aqueous ammonium hydroxide solution. 9. (a) moving the carbon fiber as an anode through a first electrolytic bath consisting of an aqueous solution of about 0.5 to about 20 weight percent nitric acid; carbon having a surface elemental content of at least 7% oxygen and at least 4% nitrogen, the carbon fiber having been surface treated by a process comprising passing through a second electrolytic bath consisting of an aqueous solution of about 5M ammonium hydroxide; fiber.