JPS6234780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reinforced composite material comprising an epoxide resin and a reinforcing material, and a method for producing the same.

Composite structures are generally made by impregnating fibrous materials (e.g., paper, glass, and carbon fiber) with a solution of a solid thermosetting resin and a heat-activated curing agent for the resin, and then evaporating the solvent to form the resin composition. is produced by solidifying and, if desired, curing by heating. Composite structures are produced by laying a coating of a resin composition on a fiber reinforced material, applying heat and pressure to allow the resin composition to flow around the fibers while leaving a curable state, and then coating the fibers if desired. The resin composition can also be produced by further heating and curing the resin composition with a heat-activated curing agent. These two methods suffer from certain drawbacks.

If a solvent is used, it is not always possible to remove all traces of the solvent before final curing of the solvent. As a result, voids may be formed in the final composite due to evaporation of residual solvent. The use of solvents also presents difficult problems due to their toxicity or flammability or contamination. When using adhesive film, first,
A liquid thermosetting resin must be cast and then solidified to a solid state to produce the adhesive film. These additional steps increase the cost of the composite material considerably. The above two methods consume considerable energy and also require evaporation of the solvent or coagulation of the resin.

We impregnated the reinforcement with a liquid, solvent-free epoxide resin composition, which can be rapidly converted to a solid state while remaining thermosetting, as seen in conventional methods. without any flaws,
I found a way. In the novel method of the present invention, after impregnating a reinforcing material with a liquid epoxide resin composition, the impregnating composition is photopolymerized by irradiating the impregnated composition with actinic radiation in the presence of a photopolymerization catalyst without thermal crosslinking. If desired, the prepreg thus obtained is heated to sufficiently cure the prepreg with residual epoxide groups to form a composite material.

Therefore, the present invention provides for impregnating a fiber reinforced material with a liquid composition containing an epoxide resin, a photopolymerization catalyst for the epoxide resin, and a thermally activated crosslinking agent for the epoxide resin, and The material is irradiated with actinic radiation, and the epoxide resin is photopolymerized by the epoxide groups of the epoxide resin to solidify the liquid composition, provided that the epoxide resin remains in a substantially heat-curable state. There is,
A method for manufacturing prepreg is provided.

The present invention further provides prepregs produced by the method of the present invention.

The present invention also provides a method for producing a reinforced composite material, in which the prepreg of the present invention, which is still heat-curable even after photopolymerization, is further heat-cured, and a reinforced composite material produced thereby.

The reinforcement may be in the form of woven or non-woven sheets, unidirectional lengths or chopped strands, and may be made of natural or man-made fibers, in particular glass, boron, stainless steel, tungsten, silicon carbide, asbestos, aromatics. It may be in the form of group polyamide or carbon.

The compositions used to produce the prepregs of the present invention must be liquid under the conditions used in producing these prepregs;
It should preferably be solvent-free.

Epoxide resins that can be used in the composition (this application also includes monomeric substances as long as they contain more than one 1,2-epoxide group per average molecule)
is preferably a formula in which the epoxide resin is directly bonded to an oxygen, nitrogen, or sulfur atom: (In the formula, R and R ² each represent a hydrogen atom when R ¹ represents a hydrogen atom or a methyl group, or R and R ² taken together and when R ¹ represents a hydrogen atom - (represents a CH ₂ CH ₂ − group).

Such resins include, for example, the reaction of a compound containing two or more carboxylic acid groups per molecule with epichlorohydrin, glycerol dichlorohydrin, or β-methylepichlorohydrin in the presence of an alkali. Polyglycidyl and poly(β-methylglycidyl) esters obtained by this method may also be mentioned. Such polyglycidyl esters include aliphatic polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, or dimerized or trimerized linoleic acid; Polycarboxylic acids such as tetrahydrophthalic acid, 4
- methyltetrahydrophthalic acid, hexahydrophthalic acid, and 4-methylhexahydrophthalic acid; and aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid;

Alternatively, a compound containing at least two free alcoholic hydroxyl groups and/or phenolic hydroxyl groups per molecule and a suitable epichlorohydrin are reacted under alkaline conditions or alternatively in the presence of an acidic catalyst. Polyglycidyl and poly(β-methylglycidyl) ethers obtained by subsequent treatment with alkali are considered.

These ethers are, for example, acyclic alcohols such as ethylene glycol, diethylene glycol and higher poly(oxyethylene) glycols, propane 1,2-diol and poly(oxypropylene) glycol, propane-1,3-diol, Butane-1,4-diol, poly(oxytetramethylene) glycol,
Pentane-1,5-diol, hexane-1,6
-diols, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylolpropane, pentaerythritol, sorbitol, and poly(epichlorohydrin); cycloaliphatic alcohols such as resorcitol, quinitol, bis (4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane, and 1,1-bis(hydroxymethyl)cyclohex-3-one; and alcohols with aromatic nuclei, such as N,N- Bis(2-
hydroxyethyl)aniline and p,p'-bis(2-hydroxyethylamino)diphenylmethane;

or these ethers are mononuclear phenols such as resorcinol and hydroquinone;
Polynuclear phenols such as bis(4-hydroxyphenyl)methane (i.e. bisphenol F), 4,4'-dihydroxyphenyl, bis(4-hydroxyphenyl)
-hydroxyphenyl)sulfone, 1,1,2,
2-tetrakis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (i.e. bisphenol A), 2,2
-bis(3,5-dibromo-4-hydroxyphenyl)propane, and aldehydes (e.g. formaldehyde, acetaldehyde, chloral, and furfuraldehyde) and phenols (e.g. phenol itself and chlorine or carbon atoms Phenols whose rings are substituted by up to 4 alkyl groups, e.g. 4-
chlorophenol, 2-methylphenol, and 4-tert-butylphenol);

Poly(N-glycidyl) compounds include, for example, amines containing at least two amino-hydrogen atoms, such as aniline, n-butylamine, bis(4-aminophenyl)methane, and bis(4-methylaminophenyl)methane. derivatives of triglycidyl, isocyanurates; and N,N'-diglycidyl derivatives of cyclic alkylene ureas, such as ethylene urea and 1,3-propylene urea, and hydantoins, such as 5,5
-N,N'-diglycidyl derivatives of dimethylhydantoin. Poly(N-glycidyl) compounds are not suitable if the photopolymerization or thermal crosslinking step involves reaction with Lewis acid.

Poly(S-glycidyl) compounds include, for example, dithiols such as ethane-1,2-dithiol and bis(4-mercaptomethylphenyl).
Di-S-glycidyl derivatives of ethers are considered. Epoxide resins having one or more groups represented by the formula in which R and R ² are bonded together to represent a -CH ₂ CH ₂ - group include, for example, bis(2,3-epoxycyclopentyl) ether,
Examples include 2,3-epoxycyclopentyl glycidyl ether and 1,2-bis(2,3-epoxycyclopentyloxy)ethane.

Examples of epoxide resins having 1,2-epoxide groups bonded to different heteroatoms include 4-
N,N,O-triglycidyl derivatives of aminophenols, glycidyl ether-glycidyl esters of salicylic acid, 1-glycidyl-3-(2-glycidyloxypropyl)-5,5-dimethylhydantoin, and 2-glycidyloxy-1,
3-bis(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane may be used. Epoxide resins may be used in which some or all of the epoxide groups are not terminal groups, examples of which include vinylcyclohexene dioxide, limonene dioxide, dicyclopentadiene dioxide, 4-oxatetracyclo[6,2,1,0 ² , ⁷ , 0 ³ , ⁵ ] Undec-9-glycidyl ether, ethylene glycol bis(4-oxatetracyclo[6,
^{2,1,02,7,03,5 ] undecyl} -9-ether, 3,4- ^{epoxycyclohexylmethyl}
3',4'-Epoxycyclohexanecarboxylate and its 6,6'-dimethyl derivative, ethylene glycol bis(3,4-epoxycyclohexanecarboxylate), 3-(3,4-epoxycyclohexyl)-8,9- Epoxy-2,4-
Mention may be made of dioxaspiro[5,5]undecane and epoxidized butadiene or copolymers of butadiene with ethylenic compounds (eg styrene and vinyl acetate). Mixtures of epoxide resins may be used if desired.

Polyglycidyl ethers, particularly polyglycidyl ethers of polynuclear phenols (eg bisphenols A and F), are suitable for use in the present invention.

Photopolymerization catalysts suitable for use in the process of the invention include, for example, ortho-alkylnitrobenzenes, organohalogen compounds, certain chromates and dichromates, and aromatic onium salts, especially diazonium salts (these salts are chemically Lewis acid is liberated by radiation irradiation).

As an aryldiazonium compound, the following formula: or the following formula: (In the above two formulas, R ³ , R ⁴ and R ⁵ are independently hydrogen atoms, halogen atoms, alkyl, alkoxy, aryl,
Represents a nitro or sulfonyl group. ) Fluoroborates represented by:
Fluoroborates and the use of these salts in the photopolymerization of epoxy compounds are described in US Pat. No. 3,205,157.

Other industrially available aryldiazonium fluoroborates that can be used include, for example, the following formula: or the following formula: [In the above two formulas, R ⁴ and R ⁵ represent the meanings defined above,
Q is an oxygen atom, a sulfur atom, or an imino (-
NH-) group, and R ⁶ and R ⁷ independently represent an alkyl group, or are combined together with the nitrogen atom to which R ⁶ and R ⁷ are attached to form an oxygen atom, a sulfur atom, or a secondary
saturated or unsaturated 5- which may contain a nitrogen atom
Or it represents a residue of a 6-membered heterocyclic ring. ] Salts represented by:

Examples of the diazonium fluoroborate include diphenylamine-4-diazonium fluoroborate, 2,5-diethoxy-4-morpholinobenzenediazonium fluoroborate, and 2,5-diazonium fluoroborate.
-diethoxy-4-(para-tolylthio)benzenediazonium fluoroborate, 4-(diethylamino)-benzenediazonium fluoroborate, 3-methoxy-4-pyrrolidinobenzenediazonium fluoroborate, and 4-morpholinobenzene Diazonium fluoroborate is particularly suitable.

Further suitable aryldiazonium compounds include, for example, the following formula: [In the formula, ^R8 represents a halogen atom or a nitro, N-morpholino, alkyl, alkoxy, aryl, amino, arylamino, alkylamino, or arylmercapto group, n represents the oxidation number of M, and m represents a diazonium salt. and MXn+m represents hexachlorostanaate, tetrachloropherate, hexafluorophosphate, hexafluoroarsenate, hexachloroantimonate, hexafluoroantimonate, or pentachlorobismacate. ] Compounds represented by are considered. These compounds and their use for photopolymerizing epoxide resins are covered by British Patent No.
It is described in the specification of No. 1321263.

Suitable ortho-alkylnitrobenzenes include, for example: (In the formula, R ⁹ and R ¹⁰ are hydrogen atoms or alkyl, aryl, carbalkoxy, pyridyl, carbazolyl, N-oxide pyridyl, nitroalkyl, nitroaryl, alkaryl, aralkyl,
represents a haloalkyl or haloaryl group,
And R ¹¹ represents a hydrogen atom or an alkyl, aryl, nitroalkyl, nitroaryl, alkaryl, aralkyl, haloalkyl, or haloaryl group. ). Such nitrobenzenes and the use of these compounds for photopolymerizing epoxide resins are described in DE 2361141 A1.

An organohalogen compound containing an alkyl, aryl, alkaryl, aralkyl, alkoxy, or aryloxy group and the following formula: (R ¹² ) ₃ E (wherein E represents a phosphorus, antimony, arsenic, or bismuth atom, and R ¹² each represents a hydrogen atom or a hydrocarbon group in which at least one of the R ¹² groups is a hydrocarbon group. ) is described in US Pat. No. 3,895,954 as a compound for photopolymerizing epoxide resins.

For photopolymerization of epoxide resins, e.g. chromates or dichromates of alkali metals, alkaline earth metals or ammonium, or polyhalogenated organic compounds which yield free radicals of halogens with relatively low bond dissociation energies; For example, the use of iodoform, carbon tetrabromide, tetrabromo-ortho-cresol, tetrachlorobenzene, tetrabromobutane, or carbon tetrachloride is described in US Pat. No. 3,782,952.

Other aromatic onium salts which liberate Lewis acids by irradiation with actinic radiation include, for example, aromatic salts of elements of groups a and a of the periodic table, such as aromatic ammonium, arsonium, phosphonium , sulfoniums, and selenoniums, and aromatic halogenonium salts, such as aromatic iodoniums, such as tetrafluoroborates, hexafluorophosphates, hexafluoroantimonates, hexachloroantimonates. , tetrachlorostanate, tetrachloropherate, pentachlorobismacate, acid sulfates, nitrates, and hexafluoroarsenates. Aromatic groups include, for example, phenacyl and phenyl groups, tetrafluoroborate of triphenylsulfonium or diphenylethylsulfonium, hexafluorophosphate of triphenylsulfonium and diphenylethylsulfonium, and particularly preferably triphenylphenacylphosphonium fluoro Examples include borates. Such compounds and their use for photopolymerizing epoxide resins are described in Belgian patents 828668, 828669 and 828670 and in German patent application No. 2602574. Are listed.

Heat-activated crosslinking agents for epoxide resins include, for example, polycarboxylic anhydrides, dicyandiamide,
It may also be a complex of boron trifluoride or boron trichloride with, for example, an amine (such as a tertiary amine), a latent boron difluoride chelate, an imidazole, or an aromatic polyamine. dicyandiamide and
A complex of boron trifluoride or boron trichloride with an amine is preferred because it is effective even in a very small proportion. The thermally activated crosslinking agent is typically dissolved or suspended in the liquid composition prior to impregnating the fiber reinforcement with the liquid composition.

The amount of photopolymerization catalyst present is usually determined by the amount of the epoxide resin.
0.1 to 20 parts by weight per 100 parts by weight, preferably 1
and 10 parts by weight. The amount of heat-activated crosslinking agent is usually 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight per 100 parts by weight of epoxide resin.

Preferably wavelength 200-600nm at photopolymerization stage
using actinic radiation. Suitable sources of actinic radiation are, for example, carbon arcs, mercury vapor arcs, fluorescent lamps with ultraviolet-emitting phosphors, argon and xenon glow lamps, tungsten lamps and photographic flood lamps. Of these, mercury vapor arcs, especially solar lamps, fluorescent solar lamps, and metal halide lamps are most suitable. The time required for irradiation depends on various factors, such as the respective epoxide resin used, the amount of the resin on the reinforcement, the type of light source, and the distance of the light source from the impregnated material. Appropriate times are readily determined by those skilled in the photopolymerization art, but the product thus photopolymerized must still be curable by heating. Of course, the irradiation is carried out at a temperature below the temperature at which thermal curing substantially occurs.

The temperatures and heating times necessary for curing epoxide resins can be easily found by routine experimentation and are already well known in any case for the generally available heat-activated crosslinkers.

The amounts of epoxide resin, photopolymerization catalyst, and thermally activated crosslinking agent are preferably such that the prepreg contains 20 to 80 weight percent of these components and correspondingly 80 to 20 weight percent of reinforcement. applied to reinforcement materials. More preferably, a total of 30 to 50 weight percent of these components and 70 to 50 weight percent of reinforcement are used.

The prepreg produced according to the invention may be in the form of a flat plate or a shaped article. If you need a product that is hollow in shape, it can be impregnated with a continuous tow of fiber reinforcement,
Particularly good results are obtained if the tow is wound onto a winding form and is simultaneously irradiated with actinic radiation. Such wound fibers have a certain degree of flexibility, and hard wound fibers have a certain degree of flexibility.
It can be removed more easily than when it is generated in stages. If desired, heat the filament winding to fully cure it.

Next, the present invention will be explained with reference to examples. Temperatures are in degrees Celsius and parts are parts by weight unless otherwise stated. The epoxide content was determined by titrating a 0.1N solution of perchloric acid in glacial acetic acid using an excess of tetraethylammonium bromide, crystal violet, as an indicator.

The interlaminar shear strength quoted is the average of three measurements and was determined by ASTM method D2344-72.

Example 1 5 parts of diphenylamine-4-diazonium fluoroborate and 3 parts of dicyandiamide were added to 2,2-bis(4
-glycidyloxyphenyl)propane to 100 parts. A prepreg was produced by impregnating a glass cloth (plain weave) with this liquid composition, and then irradiating both sides of the glass cloth thus impregnated with a 500 W medium pressure mercury lamp from a distance of 15 cm for 60 seconds.

Next, 6 boards of 15cm square prepreg pieces were
1 by pressurizing at 170℃ for 1 hour under a pressure of 2.1MN/ ^m2 .
A six-layer glass cloth laminate was produced. This laminate (composed of 37.5% resin and 62.5% glass) had an interlaminar shear strength of 15.2 MN/ ^m2 . After the laminate was soaked in hot water for 2 hours, its interlaminar shear strength was still 13.0 MN/m ² .

Example 2 5 parts of diphenylamine-4-diazonium fluoroborate and 4 parts of boron trichloride complex of n-octyldimethylamine were added to 2,2-bis(4-glycidyloxyphenyl)propane (epoxide content 5.2 equivalents/Kg) Added to 100 parts. This liquid composition was used to make prepreg as described in Example 1.

Next, six 15cm square pieces of prepreg were placed.
Pressurized at 120℃ for 1 hour under a pressure of 2.1MN/ ^m2 ,
A glass cloth laminate consisting of six layers was produced.
This laminate (composed of 38.5% resin and 61.5% glass) had an interlaminar shear strength of 14.8 MN/ ^m2 .

Example 3 5 parts of triphenyl phenacyl phosphonium fluoroborate and 4 parts of dicyandiamide were dissolved in 2,
60 parts of 2-bis(4-glycidyloxyphenyl)propane (epoxide content 5.2 equivalents/Kg) and vinyl-4-cyclohexene dioxide (epoxide content
6.8 equivalents/Kg) was added to a mixed solution of 40 parts. This liquid composition was then used to make a prepreg by the method described in Example 1, except that the impregnated glass cloth was irradiated with actinic radiation for 10 minutes. This laminate (consisting of 24% resin and 76% glass) had an interlaminar shear strength of 7.4 MN/ ^m2 .

Example 4 Poly(para-phenylene terephthalamide)
diglycidyl hexahydrophthalate (epoxide content 6.5 equivalents/
Kg), 5 parts of diphenylamine-4-diazonium fluoroborate, and 5 parts of trifluoride-monoethylamine complex was impregnated. Prepreg produced in this way is 365 mμ
It was irradiated for 10 minutes with a high-pressure metal halide quartz lamp that radiates powerful radiation in the band. Six 15 cm square pieces of this prepreg were pressed under 2.1 MN/m ² at 120° C. for 1 hour and at 150° C. for 1 hour to produce a 6-layer laminate from the prepreg. Poly(meta-phenylene isophthalamide) fibers could be used as well.

Example 5 A unidirectional carbon fiber was impregnated with a composition consisting of 100 parts diglycidylhexahydrophthalate, 30 parts bis(4-aminophenyl)methane, and 5 parts diphenylamine-4-diazonium fluoroborate, and then The carbon fibers thus impregnated were irradiated with a high-pressure metal halide quartz arc lamp from a distance of 15 cm for 15 minutes. The prepreg thus obtained was heated at 120°C under a pressure of 1.4MN/ ^m2 .
A three-layer laminate was produced by heating at 180° C. for 2 hours.

Example 6 3 parts of triphenylsulfonium hexafluorophosphate, 4.9 parts of dicyandiamide and 4.9 parts of chlortoluron are mixed with (a) 30 parts of 2,2-bis(4-glycidyloxyphenyl)propane with an epoxide content of 5.2 equivalents/Kg; (b) Epoxide content 5.61
50 parts of an epoxy novolac resin which is a polyglycidyl ether of phenol formaldehyde novolac with an average molecular weight of 420 and an average molecular weight of 420; (c)
20 parts of 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate with an epoxide content of 7.00 equivalents/kg. A prepreg was produced by impregnating a glass cloth (200 g/m ² plain weave) with this liquid composition, and then irradiating both sides of the cloth with a 200 watt/inch medium pressure mercury lamp from a distance of 25 cm for 20 seconds.

By pressurizing 8 sheets of the 20 square cm prepreg at 140°C under a pressure of 1.4 MN/m ² for 1 hour,
A glass fabric laminate consisting of layers was produced. This laminate consisting of 22.8% epoxide resin and 77.2% glass had an interlaminar shear strength of 38.9 MN/m ² .

Example 7 Diphenyl iodonium hexafluorophosphate (3
Example 6 was repeated using dicyandiamide and chlortoluron. The resulting laminate contains 25.9% epoxide resin and glass
74.1%, and had an interlaminar shear strength of 37.0 MN/m ² .

Claims (1)

[Scope of Claims] 1. A liquid composition containing an epoxide resin and a photopolymerization catalyst for the epoxide resin, and a thermally activated crosslinking agent for the epoxide resin are impregnated into a fiber reinforced material, and the impregnated fiber reinforced material is The epoxide resin is photopolymerized by the epoxide groups of the epoxide resin by irradiation with actinic radiation to solidify the liquid composition, but the epoxide resin remains in a substantially heat-curable state. A method for producing prepreg. 2. The method of claim 1, wherein the heat-activated crosslinking agent is dissolved or suspended in the liquid composition before impregnating the fiber reinforcement with the liquid composition. 3. The method according to claim 1, wherein the photopolymerization catalyst comprises 0.1 to 20 parts by weight per 100 parts by weight of the epoxide resin. 4. The method of claim 1, wherein the heat-activated crosslinking agent comprises 0.5 to 20 parts by weight per 100 parts by weight of epoxide resin. 5. The method according to claim 1, which uses actinic radiation having a wavelength of 200 to 600 nm. 6. The method of claim 1, wherein the prepreg contains 20 to 80 weight percent epoxide resin, a photopolymerization catalyst, and a thermally activated crosslinking agent. 7. The method of claim 1, wherein the fiber reinforcement comprises glass, boron, stainless steel, tungsten, silicon carbide, asbestos, aromatic polyamide, or carbon. 8 The following formula in which the epoxide resin is directly bonded to an oxygen atom, nitrogen atom, or sulfur atom: (In the formula, R and R ² each represent a hydrogen atom when R ¹ represents a hydrogen atom or a methyl group, or R and R ² taken together and when R ¹ represents a hydrogen atom - _2. The method according to claim 1, which contains a group represented by _CH2CH2- . 9. The method according to claim 1, wherein the photopolymerization catalyst is an aromatic onium salt that liberates Lewis acid upon irradiation with actinic radiation. 10. The method according to claim 9, wherein the onium salt is a diazonium salt. 11 Diazonium salt has the following formula: (In the above formula, R ⁴ and R ⁵ each independently represent a hydrogen atom or a halogen atom, or an alkyl, alkoxy, aryl, nitro or sulfonyl group, and Q represents an imino (-NH-) group) 11. The method according to claim 10, wherein the fluoroborate is a fluoroborate salt. 12 Claim 9, wherein the photopolymerization catalyst is aromatic phosphonium or sulfonium tetrafluoroborate or hexafluorophosphate
The method described in section. 13. The method according to claim 9, wherein the photopolymerization catalyst is an aromatic halogen onium salt. 14 The photopolymerization catalyst is aromatic iodonium tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, tetrachlorostanaate, tetrachloropherate, pentachlorobismacate, acidic sulfuric acid 14. The method according to claim 13, which is a salt or a nitrate. 15. The method of claim 1, wherein the thermally activated crosslinking agent is dicyandiamide, an aromatic polyamine, or a complex of boron trifluoride or boron trichloride with an amine. 16 A liquid composition consisting of an epoxide resin, a photopolymerization catalyst, and a heat-activated crosslinking agent for epoxide resin is impregnated into a fiber reinforcing material, and the epoxide resin impregnated into the fiber reinforcing material is partially polymerized by actinic irradiation. A prepreg comprising a fiber reinforcement and a solid thermosetting resin composition produced by converting the composition into a solid but thermosetting state.