JPH0112864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a wholly aromatic polyamide fiber with improved adhesion to a matrix resin and a fiber-reinforced resin composite using the fiber as a reinforcing component.

Prior art Poly(3,4'-oxydiphenylene terephthalamide/p-phenylene terephthalamide) copolymer,
So-called "aramid fibers" made of fully aromatic polyamides such as poly(p-phenylene terephthalamide) and poly(m-phenylene isophthalamide)
Because it has good mechanical properties and heat resistance, it is widely used in aircraft, space equipment, automobiles, electronic equipment, etc. as a fiber-reinforced composite material by combining it with various matrix resins. There is. That is, the fiber reinforced composite material is widely used in the form of a laminate board, a honeycomb board, a filament winding molded product, a pultrusion molded product, FRTP, etc. using unidirectional prepreg or woven fabric.

However, since these wholly aromatic polyamide fibers are chemically stable, that is, inert, and have a very high secondary transition point, it has been pointed out that they have poor adhesion with various resins used as matrices. It has been done.

However, although methods have been proposed to improve the adhesion of fully aromatic polyamide fibers when used as reinforcing materials for rubber products (Japanese Patent Publication No. 53-1999),
No. 37473), no effective method for improving adhesion with resin is known yet.

Purpose of the Invention The purpose of the present invention is to provide a wholly aromatic polyamide fiber with significantly improved adhesion to resin, and a fiber-reinforced resin composite with high tensile shear strength, delamination strength, etc., using the fiber as a reinforcing component. It's about doing.

Structure of the Invention In order to improve the adhesion of fully aromatic polyamide fibers with matrix resin, the fiber surface must have a high affinity or reactivity with the fully aromatic polyamide and also be reactive or have a strong affinity with the matrix resin. It is considered that a method of forming an adhesive layer having the following properties is suitable.

Therefore, as a result of extensive research, the present inventor found that there is a possibility of reacting with fully aromatic polyamide fibers, and that epoxy resins, polyimide resins,
We focused on polyalkyleneimine compounds as compounds that are reactive with major matrix resins such as unsaturated polyester resins and phenolic resins.
For example, polyethyleneimine has these properties and is thought to be able to improve adhesiveness.

However, such polylower alkylene imines have extremely high hydrophilicity, and there is a concern that the adhesive layer formed thereby will also be a layer with too high hydrophilicity.

As a result of intensive research based on the above findings, the present inventors have found that if an adduct (adduct) in which an oligoalkylene imine and an epoxy compound are reacted in advance is used, it is possible to maintain hydrophilicity while maintaining reactivity toward both as described above. It has been found that the balance between properties and hydrophobicity can be adjusted, and the affinity with epoxy resins and the like can also be improved. As a result of further studies, it was confirmed that by coating fully aromatic polyamide fibers with the above-mentioned adduct, the adhesion between the fibers and the matrix resin was dramatically improved, and the present invention was achieved. be.

That is, the present invention provides (1) a fully aromatic fiber with improved adhesion to matox resin, characterized in that at least a portion of the fiber surface is coated with an adduct of an oligoalkylene imine and an epoxy compound; (2) A fully aromatic polyamide fiber whose surface is coated with an adduct of an oligoalkylene imine and an epoxy compound as a reinforcing material, and has excellent mechanical properties. It is a fiber-reinforced resin composite.

In the present invention, examples of the wholly aromatic polyamide fiber serving as the substrate (fiber to be treated) include polyamide fibers comprising the following repeating units (A) and/or (B).

―CO―Ar ₁ ―CO・NH―Ar ₂ ―NH― ……(A) ―CO―Ar ₃ ―NH― ……(B) (Ar ₁ , Ar ₂ , Ar ₃ are the same or different from each other (Represents a divalent aromatic group.) Such wholly aromatic polyamide fibers include, for example, poly(m-phenylene isophthalamide), poly(p-phenylene terephthalamide), poly(4,
4′-biphenylene terephthalamide), poly(p-
benzamide), poly(3,4'-dioxydiphenyl terephthalamide/p-phenylene terephthalamide) copolymer, among others, these are classified as so-called high Young's modulus and high strength fibers. Poly(3,4'-dioxydiphenylene terephthalamide/p-phenylene terephthalamide) copolymer fibers and poly(p-phenylene terephthalamide) fibers are preferred.

On the other hand, in the present invention, an adduct of an oligoalkyleneimine and an epoxy compound is used as the coating component. The term "oligoalkyleneimine" as used herein mainly refers to those represented by the following general formula.

H ₂ N—(R—NH—) _n R′NH ₂ (However, in the formula, R and R′ represent at least one kind of alkylene group having 2 to 5 carbon atoms, and m is 0 or an integer of 10 or less. ) Such oligoalkyleneimines include, for example, ethylenediamine, diethylenetriamine,
The oligomers of oligoethyleneimine with m=0 to 10, such as triethylenetriamine, tetraethylenepentamine, and pentaethylenehexamine, or mixtures thereof are used. In addition, similar propylene imine oligomers and N,N'-bis(3
-aminopropyl) ethylenediamine, etc. can also be used.

Among the above oligoalkylene imines, m
Oligoethyleneimines with =1 to 4 are particularly preferred.

In addition, as described below, in special cases, polyethyleneimine with a high degree of polymerization may also be included in the oligoalkyleneimine referred to in the present invention.

The epoxy compound used to make the adduct is preferably one that can undergo an addition reaction with the oligoalkylene imine mentioned above to produce a soluble adduct, but generally there are 1 to 4 epoxy compounds in one molecule (particularly preferably An epoxy compound containing 2 to 3 epoxy groups is used.

Specific examples of suitable epoxy compounds include the following, which may be used alone or in combination of two or more.

Bis-phenol A diglydyl ether (including oligomeric diglydyl ethers in which bisphenol A is linked with a 2-hydroxy-trimethylene diether linkage chain) Ethylene glycol diglycidyl ether polyethylene glycol diglycidyl ether glycerin dicrycidyl ether resorcinol Diglycidyl ether N,N'-diglycidylhydantoin triphenylmethane triglycidyl ether triglycidyl isocyanurate p-aminophenol-N,N,O-triglycidyltetraphenylethane tetraglycidyl ether N,N,N',N '-Tetraglycidyl methylene dianiline Phenol novolac glycidyl ether compound Phenol glycidyl ether Styrene oxide Ethylene glycol monoglycidyl ether N-Glycidyl phthalimide In particular, when an epoxy resin is used as the matrix resin, the compatibility of the resin with the epoxy compound is It is preferable to take this into account and appropriately select the epoxy compound used for adduct production.

In order to obtain a soluble adduct, the primary amino group in the oligoalkyleneimine must be replaced by an epoxy group 2
The secondary amino group reacts with the epoxy group 1
If you try to make an adduct with equal amounts of amino groups and epoxy groups, it will easily gel, so the reaction must be carried out with a considerable excess of amino groups.

In general, when the epoxy compound is a diepoxy compound, the oligoalkylene imine is considered to be difunctional and is combined in approximately equimolar amounts with diepoxy; when the epoxy compound is trifunctional or higher, the oligoalkylene imine is From a ratio that is equivalent to epoxy, considering it as a monofunctional product, to a range where epoxy is slightly excessive,
The ratio at which a soluble product can be obtained can be determined experimentally before use.

Of course, it is preferable to carry out the reaction so that the oligoalkylene imine is constantly kept in excess during the reaction, that is, to gradually add the epoxy compound to the oligoalkylene imine. More specifically, an adduct may be generated by gradually adding a solution or a finely powdered epoxy compound to an aqueous solution of oligoalkylene imines.

The reaction temperature is from room temperature to about 60°C. It is also possible to carry out the reaction at room temperature initially, and then gradually raise the temperature after the addition of the epoxy compound is completed to complete the reaction. When adding an epoxy compound that is insoluble in water, it may be used by dissolving it in a low boiling point solvent that mixes with water, such as methanol, ethanol, acetone, or the like.

The resulting adduct is generally water-soluble, and when coating fibers, the organic solvent may be distilled off beforehand.

Generally, the reaction concentration is such that the concentration of the adduct is 3 to 20% by weight (particularly preferably 5 to 15% by weight) at the end of the reaction.

In some cases, insoluble matter may be suspended in the solution, but in this case, it is sufficient to use the solution after passing the solution.

A common method for coating the surface of fully aromatic polyamide fibers with an adduct of oligoalkyleneimine and an epoxy compound is to prepare a soluble adduct in advance and attach it to the fiber surface in the form of a solution. However, as another method,
It is also possible to first apply an oligoalkylene imine and then an epoxy compound to the fiber surface (preferably in the form of a solution), and then perform appropriate dry heat treatment to directly generate the adduct on the fiber surface. In particular, the latter method can be preferably used when the adduct has a composition that easily gels. In particular, in this case, high molecular weight polyalkyleneimines (especially polyethyleneimine)
can also be used in the same way as oligoalkyleneimines.

That is, in the latter method, an aqueous solution of oligoalkylene imine is applied to the surface of wholly aromatic polyamide fibers by spray, brush, roller, etc., or the fibers are immersed in the aqueous solution and then squeezed with a roller. Then, a solution of the epoxy compound (preferably an aqueous solution, but if it is insoluble, a solution in a low-boiling organic solvent such as acetone, methanol, or ethanol may also be used) is dried in the same manner as above. After soaking, a method of heat-treating to obtain adduct-coated fibers can be used.

However, as described above, usually a method is used in which the obtained adduct solution is applied to the fiber surface by spray, brush, roller, etc., or the fibers are immersed in the solution, squeezed, and then dried.

As the solution, an aqueous solution or a solution dissolved in a mixture of water and a low-boiling organic solvent is used, and an aqueous solution is particularly preferred. Adduct concentration in solution is 0.5-10
A suitable range is 1 to 7% by weight, preferably about 1 to 7% by weight.

It is preferable that the adduct coating formed on the surface of the wholly aromatic polyamide fiber be as uniform as possible.

The coating amount is generally 0.1 to 10% by weight based on the fiber weight.
Particularly preferred is 0.1 to 5% by weight.

The adduct aqueous solution can also be added to the fiber treatment oil and applied to the fibers simultaneously with the oil treatment of the fibers.

In the present invention, after coating the fiber surface with the above-mentioned adduct, it is preferable to perform heat treatment before applying the matrix resin, and the heat treatment temperature is generally 150°C.
The temperature used is below .degree. C., preferably about 50 to 120.degree.

In the present invention, after applying the above-mentioned adduct solution to the fiber surface, preferably an epoxy compound, a bismaleimide compound, a polyester prepolymer having an unsaturated bond, a phenol resin, a resol compound, etc., which are components of the matrix resin used, are added. Before the adduct layer is completely dried, it is applied as a solution to the upper layer to form a pre-cured layer, thereby further improving the compatibility and reactivity with the matrix resin. Can be done.

The application, shaping and curing of the matrix resin to the wholly aromatic polyamide fiber coated with the above-mentioned adduct can be carried out by conventional methods.

The morphology of the wholly aromatic polyamide fiber is strand or roving, unidirectionally aligned prepreg,
It can take various forms depending on its use, such as woven fabrics, knitted fabrics, mat-like fibers, short fibers, etc. In addition to the wholly aromatic polyamide fiber, other reinforcing fibers such as carbon fiber, silicon carbide fiber,
It can also be used in combination with glass fiber etc. in a hybrid form.

As the matrix resin, as mentioned above, major matrix resins such as epoxy resin, polyimide resin, phenol resin, and unsaturated polyester resin can be used, and in some cases, various elastomers can also be used.

The amount of fiber used in the composite (vf) is between 5 and 70
% by weight, preferably in the range from 20 to 65% by weight, particularly preferably from 45 to 60% by weight.

Effects of the Invention The fully aromatic polyamide fiber coated with the above-mentioned adduct according to the present invention has good adhesion with matrix resins, especially thermosetting resins, so that a fiber reinforced composite with excellent mechanical properties is formed. .

Various methods have been proposed for measuring the adhesion between reinforcing fibers and matrix resin in composites, and measurement is possible using any of the methods. It is common practice to measure the following.

The fiber-reinforced composite obtained by the present invention is excellent in both tensile shear strength and interlaminar shear peel strength, and can be advantageously used in various forms in various applications such as aircraft, space equipment, automobiles, and electrical equipment. be able to.

The reason why coating with such an adduct improves fiber-matrix resin adhesion is that the oligoalkyleneimine segment in the adduct has reactivity with the surface of the fully aromatic polyamide fiber and also with the main matrix resin. This is thought to be due to their sexual nature.

That is, the adduct has good reactivity and performs an addition reaction with the epoxy resin. In addition, it can react with a polyamide resin containing a bismaleimide compound by a Michael addition type reaction or by opening an imide ring with an amino group, including a normal polyimide. Furthermore, unsaturated polyesters have the possibility of easily reacting with maleic acid and fumaric acid segments by Michael addition type reaction and amidolysis into ester groups.

In addition, the epoxy compound residue in the adduct often has the effect of enhancing the affinity with the matrix resin, and is adjusted to reduce the hydrophilicity of the coating layer compared to when polyalkyleneimine is used alone. Therefore, the effect of improving the water resistance of the obtained fiber-reinforced composite material is expected.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 100 parts by weight of an aqueous solution containing 5% by weight of tetraethylenepentamine was stirred at 35 to 40°C, and prepared in advance. 160 parts by weight of a 5% by weight methanol solution (Sales Co., Ltd.) was gradually added. After 2 hours of reaction,
The amine epoxy adduct was obtained as a homogeneous solution.

The amine epoxy adduct compound solution was diluted with methanol to give a concentration of 1% by weight, 3% by weight, and 5% by weight. After impregnating a fully aromatic polyamide fiber ("HM-50" manufactured by Teijin Ltd.) made of a ramid/p-phenylene terephthalamide copolymer (copolymerization ratio 50/50) and applying the solution, The fibers were dried at 120° C. for 2 hours to obtain fibers whose surfaces were coated with amine-epoxy adducts in amounts of 1.17% by weight, 2.17% by weight, and 4.02% by weight, respectively. The coated fibers were subjected to a drum winding method using an epoxy resin matrix resin (consisting of a mixture of 20 parts by weight of "Epicoat 828" and 20 parts by weight of "Epicure Z"(4,4'-diaminodiphenylsulfone hardening agent)). It was made into prepreg.

14 sheets of this prepreg were laminated and cured using a heat press under the following curing conditions, with a fiber content (VF) of 60% by weight.
A unidirectionally reinforced composite material plate with dimensions of 127 mm long x 12.5 mm wide x 2 mm thick was obtained.

Curing conditions Temperature Time Main curing: 160°C for 20 minutes under heat press pressure Post-curing: 160°C for 2 hours under normal pressure Using the composite material plate thus obtained,
The interlaminar shear strength was measured by bending the short beam at three points in accordance with ASTMD-2344.

The values are 7.1Kg/mm ² ,
They were 7.3Kg/mm ² and 7.1Kg/mm ² . For comparison,
The interlaminar shear strength of a composite material plate obtained in the same manner using yarn without any coating treatment was 6.4 Kg/mm ² , confirming that the strength was greatly improved by the coating treatment. Ta.

Next, the above composite material board using fibers with a deposit of 2.17% by weight was compared with a similar composite material board using fibers that had not been treated at all, after each was treated in boiling water for 14 days. , take it out, wipe it thoroughly with paper, measure the weight, and based on the weight before processing,
The amount of water absorbed was measured.

In the case of coated fibers, it is 2.55% by weight, and in the case of untreated fibers, it is 2.56% by weight, and the coating treatment has no adverse effect on water absorption and therefore has no adverse effect on water resistance. It is predicted that

Example 2 Pentaethylenehexamine was used instead of tetraethylenepentamine in Example 1, and
Example 1 except that 120 parts by weight was used instead of 100 parts by weight.
An amine epoxy adduct was obtained in the same manner as in Example 1, and a copolymerized wholly aromatic polyamide fiber ("HM-50" manufactured by Teijin Ltd.) was coated with this adduct in the same manner as in Example 1, and the amount of adduct deposited was 0.69% by weight. 2.83% by weight,
4.41% by weight of each treated fiber was obtained.

A unidirectionally reinforced composite material board was made from this fiber in the same manner, and the interlaminar shear strength was measured.

The values are 7.2, 7.1, 7.3 in the order of the adhesion amount above.
Kg/mm ² , and it can be seen that the adhesiveness has been improved in both cases.

In addition, the water absorption rate after 9 days of boiling water treatment as in Example 1 was 2.54% by weight, which was not different from the untreated water absorption rate of 2.55% by weight, and there was no negative effect in terms of water resistance. It is thought that this is not given.

Example 3 Instead of “Epicote 828” alone in Example 1,
The same type of fiber was treated in the same manner as in Example 1 except that 115 parts by weight of a 5% by weight methanol solution of a mixture of 50 mol% of the same compound and 50 mol% of triglycidyl isocyanurate was used. The coated fibers were obtained, a unidirectionally reinforced composite material board was prepared in the same manner as in Example 1, and the interlaminar shear strength was measured.
It showed a value of 7.5Kg/ ^mm2 .

Example 4 Instead of “Epicote 828” alone in Example 1,
A coated fiber with a coating amount of 2.1% by weight was obtained in the same manner as in Example 1, except that 95 parts by weight of a 5% by weight aqueous solution of glycerin diglycidyl ether was used, and a unidirectionally reinforced composite material board was similarly prepared. When the interlaminar shear strength of this material was measured, it showed a value of 7.2 Kg/mm ² .

Example 5 Same as Example 1 except that poly-p-phenylene terephthalamide fiber ("Kevlar 49" manufactured by Dupont) was used instead of the copolymerized fully aromatic polyamide fiber of Example 1, but the adhesion amount was 3.31 weight. % coated fibers were obtained, and similarly unidirectionally reinforced composite material plates were obtained. This gave a delamination strength of 7.4 Kg/mm ² . When the delamination strength of a composite material plate obtained from fibers that were only washed without any treatment was measured, it showed a value of 7.1 Kg/mm ² , and compared to that, the delamination strength of the composite material board of the present invention was improved. I understand.

Claims (1)

[Scope of Claims] 1. A wholly aromatic polyamide fiber, characterized in that at least a portion of the fiber surface is coated with an adduct of an oligoalkylene imine and an epoxy compound. 2. A fiber-reinforced resin composite comprising, as a reinforcing component, wholly aromatic polyamide fibers in which at least a portion of the fiber surface is coated with an adduct of an oligoalkylene imine and an epoxy compound.