JPH0412810A - Laminated article consisting fiber reinforcing poly(allylene sulfide) prepreg - Google Patents

Abstract

PURPOSE: To obtain a carbon fiber-reinforced composition characterized by a microcrack of a low level by blending a crack inhibitor together with a long carbon fiber-reinforcing material within a poly(allylene sulfide)resin, thereby reducing the crack of a poly(allylene sulfide) matrix. CONSTITUTION: A crack inhibitor is a fine polymer substance of a fine shape dispersed in an overall poly(allylene sulfide) resin matrix. Generally, it is selected from the group consisting of a polyethylene, polypropylene and a copolymer of other monomer and polyethylene or polypropylene of about 10 wt. % or less of a powder state having a smaller particle size than about 50 μm. The inhibitor is existed in an amount of about 0.1 to 10 wt.% of the overall composition. The carbon fiber can be selected from widely various type materials. It has a length of at least 2 cm, and a diameter of a range of about 4 to 10 micron. About 50 to 80% of the composition is made of the carbon fiber by a weight reference.

Description

DETAILED DESCRIPTION OF THE INVENTION In one aspect, the present invention provides poly(arylene sulfide)
Relating to composite compositions. In another aspect, the invention relates to a method for forming a poly(arylene sulfide) composite composition. In yet another aspect, the present invention relates to incorporating additives into fiber reinforced poly(arylene sulfide) compositions.

Reinforced poly(arylene sulfide) compositions are highly suitable for forming into a variety of objects. Fibers are commonly used to strengthen such compositions.

Commonly used fibers are glass fibers, carbon fibers and aramid fibers. (Some fibers present particular problems because they exhibit anisotropic thermal expansion; carbon fibers, for example, expand only slightly along their length as the temperature increases, but expand significantly diametrically. When carbon fibers are used to strengthen poly(arylene sulfide) compositions, temperature cycling causes microcracks within the resin matrix due to the differential thermal expansion between the carbon fibers and the resin matrix. This microcracking is particularly noticeable in cross-bried, quasi-anisotropic fabric-based laminates because of the stress that occurs between the fiber groups.

When long fibers are used to reinforce poly(arylene sulfide), microcracks extending from the carbon fibers into the matrix provide pathways for liquid absorption by capillary action, which further degrades composite strength. .

The mechanism of crack formation in long carbon fiber reinforced poly(arylene sulfide) compositions is as follows:
This is different from crack formation in poly(arylene sulfide) injection molding materials, which can be reinforced by short fibers of less than m. In injection molding materials, poly(arylene sulfide) resins shrink as they solidify, causing cracking as solidification occurs first on the outer surface of the injection molded article. The resin inside the injection molding finally solidifies and occupies a smaller volume than is required to fill the volume already determined by the outside surface of the molding. As it solidifies, the deepest resin pulls away from the already solidified resin closest to the surface, creating cracks. This problem is particularly acute in thick-walled injection molded articles, for example with a wall thickness of more than 1 cm.

On the other hand, composite layups formed from unidirectional blegged legs of poly(arylene sulfide) such as polyphenylene sulfide (PPS) and long fibers exhibit microcracking, especially in cross-bried and quasi-anisotropic layups.

These microcracks can be observed by cutting the laminate, polishing the cut surface, and microscopically observing the surface using directly reflected light. The microcracks are typically less than a few microns wide and extend through the thickness of the braai. This may reduce the strength of the composite and/or increase its susceptibility to liquids degrading its properties.

The purpose of the present invention is to reduce microcracking in poly(arylene sulfide) matrices that are reinforced by long carbon fibers.

Another object of the present invention is to provide a crack inhibitor suitable for use as a matrix material with long carbon fiber reinforcement.
(arylene sulfide) into a resin.

Yet another object of the present invention is to provide carbon fiber reinforced compositions characterized by low levels of microcracking.

In one embodiment, the invention consists of a continuous poly(arylene sulfide) resin matrix that includes long carbon fiber reinforcement. A crack inhibitor polymer is dispersed within the matrix to prevent the formation and/or propagation of microcracks. The composition of the invention comprises a laminate comprising a region of long fiber reinforcement oriented in one direction and adjacent another region of fibers oriented in a direction perpendicular to the direction of the fibers. It is particularly suitable for manufacturing. This is because the mutually perpendicular orientation of the carbon fibers increases thermally induced stresses and promotes crack propagation if the fibers are oriented parallel to each other.

In another embodiment of the invention, carbon fiber reinforced poly(
A method is provided for increasing the microcracking resistance of a (arylene sulfide) resin matrix. In embodiments of the invention, a crack inhibitor polymer is dispersed throughout the resin matrix. Preferably, the poly(arylene sulfide) resin and particles of the anti-crack agent are mixed in powder form, the mixture is heated to a temperature above the softening point of the poly(arylene sulfide) resin, and the thus heated mixture is heated to a sufficient temperature. Pressure is applied to densify the resin to form a product having a continuous matrix of poly(arylene sulfide) resin with a crack-inhibiting polymer dispersed throughout.

In a further preferred embodiment of the invention, in mixing the particles of poly(arylene sulfide) resin with the second polymer particles constituting the crack inhibitor polymer, these two
by preparing an aqueous slurry of two particles, stirring the slurry, and pulling at least one roving of carbon fiber through the slurry, wherein the particles of poly(arylene sulfide) resin and the second scooping the mixture with the polymer particles, impregnating it to form a wet roving, and then at least partially drying;
Pull through a die to form a continuous resin matrix. The products formed by this method include aligned carbon fibers that can be laminated together and/or thermoformed into the desired shape.

The compositions of the present invention consist of a continuous thermoplastic matrix, a long carbon fiber reinforcement embedded within the matrix, and a crack inhibitor polymer dispersed throughout the matrix in an amount sufficient to reduce microcracks. .

The continuous thermoplastic resin matrix is preferably a poly(arylene) resin. The most preferred polyarylene resins contain monosulfide bonds, preferably poly(
arylene sulfide) (hereinafter referred to as PAS) resin. Suitable PAS resins are preferably poly(phenylene sulfide) (hereinafter referred to as PPS), poly(arylene sulfide ketone) (hereinafter referred to as PASK), preferably poly(phenylene sulfide phenylene ketone).
, poly(arylene sulfide sulfone) (hereinafter referred to as PA
SS) is preferably selected from the group consisting of poly(phenylene sulfide, phenylene sulfone), and poly(biphenylene sulfide) (hereinafter referred to as PBPS). Preferred PAS resins generally have softening points ranging from about 250°C to about 450°C and from near zero to about 400°C.
It may have a melt flow in the range of grams per 10 minutes. Materials of high utility will exhibit melt flows (ASTM DI238) in the range of about 5 to about 200 grams/10 minutes.

A wide variety of materials can be suitably used as crack inhibitors. The anti-crack agent should be dispersed throughout the poly(arylene sulfide) resin matrix in fine form. The anti-crack agent is preferably a finely divided polymeric material, most preferably in powder form, generally having a particle size of less than about 50 μm. In one embodiment, the particles can be characterized as having a cross-sectional size such that at least 90%, by number of particles, can pass through a 50 micron filter. However, it is not necessary that the anti-crack agent be so finely ground that it essentially dissolves within the poly(arylene sulfide) matrix. In an embodiment of the invention that has been used with good results, the powdered anti-crack agent has a cross-sectional size that provides at least 90% retention by weight on a 1 micron filter. can be further characterized as being composed of particles having In one embodiment of the invention, the crack inhibitor has an average particle size ranging from about 2 microns to about 20 microns on a weight basis. In this embodiment, the crack inhibitor particles are as large as the diameter of the carbon fibers reinforcing the resin.

Most desirably, the crack inhibitor is a type of polymer that has a decomposition temperature higher than the temperature at which the poly(arylene sulfide) resin matrix is processed. The processing temperature is
Generally several degrees higher than the softening point of the resin. Suitable polymers from which crack inhibitors are selected include polyethylene, polypropylene, poly-4-methyl-1-pentene, nylon 6, nylon 6.6. polyamides such as nylon 11 or nylon 12, polyesters such as polyethylene terephthalate or polybutylene terephthalate, polystyrene,
These are styrene-acrylonitrile copolymer, polysulfone, and polyethersulfone. Copolymers of these materials can be used as well. In a preferred embodiment, the crack inhibitor is selected from the group consisting of polyethylene, polypropylene, and copolymers of polyethylene or polypropylene with up to about 10% by weight of other monomers. Suitable comonomers are propylene, butene,
It is selected from polyalpha-olefins such as hexene, octene or 4-methyl-1-pentene, acrylic acid or methacrylic acid. The acid radicals may be partially or totally converted into salt form by sodium, ammonium, carunium or zinc ions. Ethylene polymers are most preferred. The most preferred ethylene polymers are high density ethylene polymers, preferably having densities ranging from about 0.694 to about 0.97 grams/CC. Although the melt index of the ethylene polymer selected is not critical, the most preferred ethylene polymers are
It has a melt index ranging from near zero to about 400 grams/10 minutes, preferably from about 2 to about 200 grams/10 minutes.

The carbon fibers used in the present invention can be selected from a wide variety of materials. Long carbon fibers are preferred.

Long means carbon fibers having a length of at least 2 cm, preferably at least 10 cm.
means carbon fibers with an average length of centimeters. Continuous carbon fibers are most preferred. Such carbon fibers are preferably present in the matrix in the form of discrete bundles or rovings of carbon fibers or filaments.

The individual filaments within the roving typically range from about 4 to about 1
It may have a diameter in the range of 0 microns. Typically, each roving will contain on the order of 1000 to about 12000 filaments. The invention is also applicable to carbon fiber fabrics where the individual filaments can be as specified above.

Generally, from about 50% to about 8% of the composition of the invention by weight
0% may consist of carbon fiber. Preferably, about 55 to about 70% by weight of the compositions of the present invention will consist of carbon fibers. The anti-crack agent preferably accounts for about 0.1 to 0.1 of the total composition.
Present in an amount of 10% by weight. Preferably, from about 0.2 to about 0.2% of the composition of the present invention, based on the weight of carbon fiber, poly(arylene sulfide) resin matrix, and crack inhibitor.
There will be an anti-crack agent present in the range of about 5% by weight. The remainder of the composition consists of PAS resin. Preferably, no more than about 5% by weight of the composition is formed by components other than the long carbon fibers, crack inhibitor and PAS resin. Most preferably, the remainder of the composition consists essentially of PAS resin.

The crack inhibitor is dispersed throughout the continuous resin matrix. Long carbon fiber reinforcement is embedded within the matrix. Preferably, the individual fibers within the carbon fiber reinforcement are oriented substantially parallel to one or more major reinforcement axes within the product. In the case of structural members such as bars, I-beams, and tapes, the primary reinforcement axis will coincide with the longitudinal axis of the product.

In the case of plates, there are several reinforcing shafts in the product for boat fishing. For example, if the board is formed from fabric, there will typically be two reinforcements oriented at 90° to each other. In the case of plates containing laminated plies, there are often a number of reinforcing axes separated by, for example, 45° angles or 90° angles.

The components of the compositions of the invention can be combined by a variety of methods. The most important criterion to adhere to is that the anti-crack agent polymer be dispersed throughout the resin matrix of the final product.

Initially, the poly(arylene sulfide) resin can be supplied in any convenient form, such as powder, pellets, or sorts.

This resin is mixed with particles of crack inhibitor polymer to form a mixture. If desired, the crack inhibitor can be blended with the matrix precursor in a mixer or extruder and combined with the carbon fibers in premixed form. For example, a resin containing particles of crack-inhibiting polymer can be supplied in the form of a film for stacking with carbon fibers. In another embodiment, the resin and anti-crack agent are premixed and fed to a crosshead extruder, which is also fed with carbon fiber roving. In yet another embodiment, an aqueous slurry of PAS particles further comprising particles of a crack inhibitor is prepared and at least one roving of carbon fibers is drawn through the slurry. When employing such slurry impregnation of carbon fibers, the particles within the slurry desirably have an average particle size of about 2 microns to about 50 microns on a weight basis. - For boat fishing, about 20 to about 500 parts by weight of P per 1 part by weight of crack inhibitor.
AS is present within the slurry. In the most preferred embodiment, the crack inhibitor consists of polymer particles having a thermal decomposition temperature higher than the softening temperature of the PAS particles. The slurry is stirred and surfactant is added if necessary to provide a uniform distribution of the anti-crack agent. Carbon fibers are scooped from a slurry of a mixture of poly(arylene sulfide) and second polymer particles, thus forming an impregnated wet roving, which is then at least partially dried and drawn through a hot die. method to remove it from the slurry. The temperature inside the die is sufficiently high, −
For boat fishing, the temperature is approximately 10° to 100° above the softening point of PAS to soften the PAS matrix, and the die has a sufficiently small cross-sectional size (sufficient to melt the PAS particles into a continuous resin matrix). Can apply pressure.

Preferably, the dies converge from the inlet to the outlet.

Products made according to the invention can often be distinguished from injection molded products not only by their size but also by the orientation and length of the carbon fibers they contain. Long carbon fiber reinforced composite products are often less than about 1 centimeter, usually 0.
It has a size of less than 5 centimeters.

The invention is further illustrated by the following examples.

(Example) Example I Fine polyethylene (Allied C-6A low density polyethylene) was mixed at a ratio of 1 part to 50 parts of non-air cured fine poly(phenylene sulfide) at a flow rate of 50 g/10 minutes. . This was then further ground in an air mill to give thoroughly mixed particles in the 20 μm size range. The obtained mixed powder was added to a diluted aqueous solution of an ethoxylated octylphenol nonionic surfactant (Finnyanntylaneyon surfactant) with strong stirring. The concentration of polyphenylene sulfide/polyethylene mixture in the resulting slurry was about 10%, and the concentration of surfactant relative to the total weight of the slurry was about 0.01%.

The carbon fibers were then drawn through an agitated slurry, through a high temperature air oven, and into a hot forming die at approximately 650'F to produce a tape suitable for fabrication into multilayer laminates. The carbon fiber content of the tape was typically 60% and the tape thickness was 7 mils.

Example ■ 5.1 g of fine polyphenylene sulfide with a melt flow of 50 g/10 minutes was stirred vigorously and 48 ml of the nonionic surfactant ethoxylated octylphenol was added to 43
kg of water to form the first portion of the impregnating slurry.

Ethylene acrylic acid copolymer suspension (trade name M1ch
em Prime 4990) 307 g portions were poured in a thin stream with 3 kg of strongly stirred water to form the second portion of the impregnating slurry. The second part is then added to the first part with stirring, and the carbon fibers are passed through the resulting slurry, passed through a drying oven, and drawn through a hot forming die to obtain approximately 60% by weight of carbon fibers. A tape was produced with a thickness of 7 mils.

Example■ Microcracks in the sample were evaluated using the following method.

Prepreg tape spliced to length 10 inches width 10
I made inch tape. These tapes are then stacked so that the fiber orientation is 0. 90. 0°90, 90.
0. 90. 0 (simply expressed as (0,90) 2S) and molded at 625° C. for 4 minutes under contact pressure and 10 minutes at 150 psi to form 1
It was made into a 0 inch molded product. The molded product was immediately transferred to a cold compressor and compressed at 150 ps1 without cooling. After removal from the compressor, the sample was placed in a circulating air oven for 15 minutes.
Annealing was performed at 0°C for 2 hours. The thickness of the laminate is 50-6
It was 0 mil. Approximately 1 inch wide laminate strips are then cut from the laminate at a 45° angle with fiber orientation, packed in cold cure epochino, then cut with a low speed diamond canter, and finally: It was polished with a series of increasingly smaller grids terminating in 1 μm diamond or 05 μm alumina.

The polished surface was then examined by optical microscopy at 40-400X magnification. Where microcracks were observed, they were typically less than 3 μm wide and extended to the width of one braai. The polyethylene-containing sample (Example I) contained virtually no microcracks, and the ethylene acrylic acid copolymer-containing sample (Example ■) contained very few microcracks. In contrast, a control sample containing neither polyethylene nor ethylene acrylic acid copolymer
10-2 per centimeter at regular intervals
Contained 0 microcracks.

The microcracks appear to arise from the stresses induced by the cooling process due to the low expansion coefficient of the carbon fibers in the longitudinal direction and the relatively high expansion coefficients of the resin and fibers in the transverse direction. This creates transverse tensile stresses in each ply that are greater than the stresses that can be supported by the carbon fiber resin interface. Additionally, a beneficial effect of polyethylene or ethylene acrylic acid polymers appears to be to reduce stress during cooling.

(4 other people)

Claims (14)

[Claims] 1. A laminate consisting of a plurality of prepreg layers heat-fused together, each prepreg layer having a continuous resin matrix and comprising about 50 to 80% by weight of the resin matrix in the matrix, based on a 100% by weight layer. 100% by weight comprising carbon fibers, about 0.1 to 10% by weight of a finely divided form of anti-crack agent dispersed throughout the resin matrix, and a poly(arylene sulfide) as the resin matrix.
the carbon fibers have a length of at least about 2 centimeters and a diameter of about 4 to 10 microns, and the crack inhibitor has an average particle size of less than about 50 microns. and is a copolymer of ethylene or propylene with up to about 10% by weight of polyethylene, polypropylene or other monomers, based on the total copolymer weight.
Laminated product resistant to microcracks. 2. A laminate according to claim 1, wherein said anti-crack agent comprises polyethylene. 3. The polyethylene has a density in the range of about 0.94 to 0.97 grams per cubic centimeter and about 2
A laminate according to claim 2, having an average particle size in the range ˜20 microns. 4. A laminate according to any one of claims 1 to 3, wherein the carbon fibers are continuous. 5. 5. The laminate of claim 4, wherein the carbon fibers are oriented substantially in one direction in each of the prepreg layers. 6. A laminate according to any one of claims 1 to 5, wherein the carbon fibers are in the form of a woven fabric in each of the prepreg layers. 7. A laminate according to any one of claims 1 to 5, wherein the carbon fibers of one of the layers are angled relative to the carbon fibers of an adjacent layer. 8. 8. The laminate of claim 7, wherein said angle is about 90 degrees. 9. 8. The laminate of claim 7, wherein said angle is about 45[deg.]. 10. The laminate according to any one of claims 1 to 9, wherein the crack preventive agent has a particle size that is approximately the same as the diameter of the carbon fiber. 11. A laminate consisting of a plurality of prepreg layers heat-fused together, each prepreg layer having a continuous resin matrix and comprising about 50 to 80% by weight of the resin matrix in the matrix, based on a 100% by weight layer. 100% by weight comprising carbon fibers, about 0.1 to 10% by weight of a finely divided form of anti-crack agent dispersed throughout the resin matrix, and a poly(arylene sulfide) as the resin matrix.
the carbon fibers have a length of at least about 2 centimeters and a diameter of about 4 to 10 microns, and the crack inhibitor is an ethylene polymer and has a diameter of about 0.0 microns per cubic centimeter. A laminate resistant to microcracking having a density ranging from .94 to .97 grams. 12. A laminate consisting of a plurality of prepreg layers heat-fused together, each prepreg layer having a continuous resin matrix and comprising about 50 to 80% by weight of the resin matrix in the matrix, based on a 100% by weight layer. 100% by weight comprising carbon fibers, about 0.1 to 10% by weight of a finely divided form of anti-crack agent dispersed throughout the resin matrix, and a poly(arylene sulfide) as the resin matrix.
the carbon fibers have a length of at least about 2 centimeters and a diameter of about 4 to 10 microns, and the crack inhibitor comprises the poly(arylene sulfide).
and has a decomposition temperature higher than the softening point of polyethylene,
Based on the weight of polypropylene or total copolymer, about 1
Laminates resistant to microcracking, which are copolymers of ethylene or propylene with up to 0% by weight of other monomers. 13. 11th, wherein the crack preventive agent is made of polyethylene;
Or the laminate product according to claim 12. 14. The poly(arylene sulfide) is poly(phenylene sulfide), poly(arylene sulfide ketone), poly(arylene sulfide sulfone), or poly(biphenylene sulfide), and the poly(arylene sulfide) is about 250° to 450°C 14. The laminate of any one of claims 1 to 13, having a softening point in the range of from near zero to about 400 grams per minute as measured by ASTM test D1238.