KR950013686B1 - Rigid composite - Google Patents

Abstract

No content.

Description

Rigid composite

1 shows the relationship between the ballistics limit (V ₅₀ ) and the resin content as weight percent of rigid composites having different area densities in a series of graphs depending on the number of crop plies in the composite. Is for rigid composites with and without adhesion modifiers.

The present invention provides a rigid composite with significantly improved ballistics performance, lighter weight and reduced area density for a given ballistic capability.

의 용도가 기술되어 있다. 이러한 적용을 위해, 통상적으로 필라멘트를 에폭시 수지 매트릭스(matrix)에 매봉(embed ; 埋封)한다. 문헌에서는, 대부분의 최종 섬유강도는 에폭시 수지를 매봉하기 전에 섬유를 5 내지 9%의 실리콘 이형제로 피복함으로써 이용할 수 있음을 제안하였다.See Mumford et al., AIAA / SAE / ASME 18th Joint Propulsion Conference, June 21-23, 1982, Cleveland, Ohio, Kevlar 49 in a filament wound pressurized vessel.

The use of is described. For this application, the filaments are typically embedded in an epoxy resin matrix. The literature suggests that most final fiber strengths can be utilized by coating the fibers with 5-9% silicone release agent before embedding the epoxy resin.

U.S. Patent No. 4,678,821 (July 7, 1987) describes an improved filament wound pressurized container wherein the epoxy-sealed filaments are coated with 2-perfluoroalkylethyl ester or paraffin wax instead of silicone release agent. .

Walling, S-2 Glass Fiber: 1ts Role in Military Applications, for the Proceedings of the Fifth International Conference on Composite Materials (ICCM-V), San Diego, CA (July 29, 30, August 1, 1985) ] Describes glass fibers as being useful for ballistic composites at increased area densities.

The present invention relates to p-aramid continuous filaments coated with about 0.2 to 5% by weight of a solid adhesion modifier, wherein the coated filaments are embedded in a polyester resin matrix, a phenolic resin matrix or a polyamide resin matrix and are MIL-STD- When tested according to 662D (March 19, 1984), it exhibits a ballistic limit of about 1,000 to 4000 ft / s ec and a composite area density of about 0.4 to 6 lb / ft ² ], reinforced polyester resin matrix, phenolic A rigid composite comprising a resin matrix or a polyamide resin matrix.

The solid red chopped modifier is preferably 2-perfluoroalkylethyl ester or paraffin wax or a mixture of these materials. The composite generally comprises about 50 to 90 weight percent, preferably about 60 to 85 weight percent of the filaments.

The present invention relates to a continuous filament reinforced rigid composite. High strength, high modulus p-aramid filaments are useful for such composites.

The term "aramid" is used to mean a wholly aromatic polyamide. Not all aramid fibers are used in the present invention. It is only preferred that the chain extension is derived primarily from aromatic polyamides which are coaxial or parallel and reverse. The chain extension is not reverse, and small amounts of aramid units may be present, provided that the filament strength and modulus are not severely reduced. For example, there may be up to 15% or slightly more units in meta-aromatic bonds. High strength, high modulus aramid fibers useful in the present invention can be prepared by the methods described in US Pat. Nos. 3,767,756, 3,869,430 and 4,075,172.

)라는 상표명으로 제조하는 폴리(p-페닐렌 테레프탈아미드)계 p-아라미드 섬유가 특히 바람직하다.The fibers are characterized as having at least 15 gpd (1.32 dN / tex) and filament strength of at least 400 gpd (354 N / tex). Such fibers are hereinafter referred to as p-aramid fibers. this. children. Kevlar at Dupont de Nemoa and Company

Particular preference is given to poly (p-phenylene terephthalamide) based p-aramid fibers produced under the trade name).

The matrix component of the composite of the present invention is a polyester resin, a phenolic resin or a polyamide resin. Such materials are known in the art and provide strong rigid structures in the cured state.

Suitable polyester resins include vinyl ester resins and ortho-polyester resins. Vinyl ester resins are reaction products of epoxy resins with unsaturated aliphatic acids such as methacrylic acid or acrylic acid. Typically the epoxy resins used are resins of diglycidyl ether / bisphenol A type and may be components such as epoxy novolacs or halogenated epoxy.

Ortho polyesters are the reaction products of glycols, unsaturated aliphatic dibasic acids or anhydrides thereof and saturated ortho aromatic acids or other anhydrides. The glycol is typically propylene glycol, but may be other glycols such as ethylene glycol, diethylene glycol, dipropylene glycol, and the like. Unsaturated dibasic acids or anhydrides are typically maleic acid, fumaric acid or maleic anhydride, but may be other similar acids or anhydrides.

Ortho aromatic acids or anhydrides are usually orthophthalic acid or orthophthalic anhydride, but may be other saturated ortho aromatic acids or modified acids halogenated by chlorine.

Vinyl ester resins and orthophthalic acid and isophthalic acid polyester resins are generally cured by reaction with monomers such as styrene or substituted styrenes (e.g. vinyl toluene or α-methyl styrene), but other monomers such as methyl Methacrylate, methyl acrylate, diallyl phthalate, triallyl cyanurate and the like can also be used.

The phenolic resin may be of resol type or novolak type. In general, the present invention uses the resol type. Phenolic resins are generally prepared by reacting phenol with an aldehyde.

Typically, formaldehyde is used, but other aldehydes may also be suitable as known. Phenols typically use phenols, but other suitable phenols include resorcinol and ring-substituted phenols such as ortho-, meta- or para-cresol, bistenol A, pt-butylenol, p-phenyl Phenols and the like.

In addition, a polyamide resin can be used as the matrix component of the composite of the present invention. Such polyamide resins should preferably be melt processable at 350 ° C or below.

Several types of such resins are useful, for example, aliphatic, cycloaliphatic and aliphatic-aromatic polyamides. Examples include 6,6 nylon; 6 nylon; 6,10 nylon; 6,12 nylon; Polyamides from 4,4'-bis (aminocyclohexyl) methane and dodecanedioic acid; Poly (hexamethylene terephthalamide); Poly (hexamethylene isophthalamide) and the like. Copolymers of these polyamides are also useful.

The composite of the present invention improves ballisticity by using filaments coated with an adhesive modifier prior to embedding. The composite of the present invention requires such a coating and uses the coating in admixture with other members of the composite defining the present invention. The coating function of the adhesion modifier is to reduce the adhesion level between the p-aramid filament and the resin matrix, as described below.

Such adhesion modifiers are applied from about 0.2 to about 5 weight percent to the filaments to obtain the desired ballistic results at the area density of the present invention.

Less than about 0.2% modifiers give inadequate results, and more than about 5% do not provide significant additional shapes.

The adhesive material may be used in any of a variety of ways to provide uniform distribution on the filament surface. For example, it can be dissolved in a solvent, applied to the filament, then the solvent can be removed, applied to the filament by dispersing in a soak (eg water), or applied directly in the absence of other components. One of the more common applications is to disperse the adhesion modifier in water. In general, as a useful method of preparing such dispersions, the adhesion modifier is melted or dissolved in an organic solvent (eg methyl isobutylketone) and mixed with an aqueous solution of the dispersant to obtain a two-phase mixture. The mixture is then stirred under high shear conditions to give a dispersion. The organic solvent is separated by distillation under vacuum, leaving the desired aqueous dispersion. Suitable dispersants are sodium dodecylbenzenesulfonate and octadecyl trimethylammonium chloride. Of course, other dispersants may also be used, and these various products are sold under the trade names "Armeen" 14D and 18D, "Merpol" OJS and HCS and "Arquad" 1250.

The adhesion modifier may be characterized as a solid that is not readily absorbed or dissolved in the filament or resin. If solid, there is less tendency to migrate during or during the use of the composite. It is important that the modifiers reduce the adhesion between the fibers and the matrix, thereby limiting the fibrous load that tends to prevent maximum utilization of the ultimate fiber strength.

In the composites of interest, preferred ballistics have been found to be achieved when the amount of impregnation of a particular modifier is low, i.e., about 0.2 to 5% by weight. If the area density is about 0.4 to 6 lb / ft ² , the preferred modifier level is about 1 to 2 weight percent.

The trajectory limit (V ₅₀ ) is determined under the conditions of ballistic tests for which weight and dimensioned projectiles have been identified as MIL-S TD-662 D [Reference: Ballistic Test for Armor (April 19, 198)]. It is defined as the rate at which the probability of penetrating the rigid composite is 50%. For composites with an area density of less than 4.0 lb / ft ² , 17 grain sprays were used in the practice of the present invention. For composites with an area density of 4.0 lb / ft ² or more, 44 grain injectors have been proposed.

Injector type is limited to MIL-P-46593.

Area density is defined as the weight per unit area of the rigid composite under test.

The ballistic test, MIL-STD-662 D, allows the test injector to be propelled while varying the known velocity for the rigid composite sample until the rate is measured when the test injector is 50% likely to penetrate the rigid composite. It includes.

One advantage of obtaining the desired adhesion at low impregnation levels is the overall weight reduction of the composite compared to the impregnation amounts of silicone materials reported in the art. Another advantage is that because of the low impregnation amount, the concentration of filament can be higher based on the weight of the composite.

Two groups of surface modifiers for p-aramid filaments useful in the present invention are certain fluoro compounds, paraffin waxes and mixtures thereof. Fluoro compounds can be described as 2-perfluoroalkylethyl esters in which the 2-perfluoroalkylethyl group has the general formula of C _n F _{2n + 1} (CH ₂ ) ₂ , wherein n is 5 to 11 Can be.

Useful esters are esters of methacrylic acid in polymer form, urethane citric acid and phosphoric acid or ammonium salts thereof and the like. Esters of this type are described in other documents (US Pat. Nos. 3,282,905 and 3,378,609). The ester can be applied in admixture with coupling agents such as other acrylic acid, methacrylic acid and / or acrylamide polymers to promote pick up and dispersibility of the fluoro compound for the p-aramid filaments.

Paraffin waxes are solids derived from petroleum with melting points above room temperature.

Paraffin waxes having a melting point of about 60 ° C. are generally preferred.

Paraffin waxes can be applied with coupling agents such as behenic acid ester derivatives of melamine to promote the pickup and dispersibility of the wax for p-aramid filaments. Mixtures of fluoro compounds and paraffin waxes are preferred surface modifiers for practicing the present invention.

The present invention is particularly useful in the ballistic composite of the area density of this invention. Such composites can withstand ballistic impact and better prevent penetration of the injector than when using uncoated filaments, when the reinforcing filaments are coated according to the present invention before they are incorporated into the resin matrix. In addition, by using such a coating, problems associated with the application of the weak silicone release agent used in the art can be avoided. The latter tends to unevenly cover the filaments and require an extended drying or curing period and are not clean when used. They generally add undesired weights to the composite using large amounts, i.e. from 5 to 9% by weight (see patents such as Mumford). The frictional properties of these silicone sheathed yarns prevent the use of such yarns in rigid composites.

Using the coated aramid filaments of the present invention, it is possible to produce very light and effective composites compared to prior art composites using glass fibers. The density of aramid filaments is about 1.45 g / cc, while the density of glass fibers is about 2.5 g / cc. Thus, the use of smaller amounts of aramid filaments than glass fibers required to provide the same ballistic results can provide lighter composites when making composites according to the present invention.

The following examples illustrate the invention representatively. In addition, manipulations or changes in the amount of addition outside the range of the described area densities can lead to ballistic limits outside the scope of the present invention.

Example 1

This example includes a process for preparing a rigid composite of the present invention and a comparative ballistic test of such a composite against a composite that does not use any adhesion modifiers. The fabric used in this example is E. children. It is a fabric made from poly (p-phenylene terephthalamide) sold under the name Kevlar 29 by DuPont de Nemoir & Company and identified as style 710. Style 710 fabrics are flats made from continuous fibers with a light and weft density of 24x24 / in (9.4x9.4 / cm), a nominal basis weight of 9.6oz / yd ² (32 6g / m2), and a nominal yarn variable of 1500d It is a fabric.

The fabric is wide-jagged to remove yarns and warp yarns. The front face is run in water containing 1 g / l of surfactant and the temperature of the water is raised from 100 ° F. (38 ° C.) to 200 ° F. (93 ° C.) in 20 ° F. (11 ° C.) increments. The fabric passes two times of water at each temperature increment and a total of 12 passes. Surfactants used in these cases are E. coli. children. Dupont de Nemoir & Company is commercially available "muffle" HCS. The fabric is washed with water, vacuum extracted and dried in a clip tenter frame at 250 ° F. (121 ° C.). In the comparative section of this example, a dry fabric is used without further treatment.

In order to make fabrics for use in the composites of the present invention, the refined and dried fabrics are subjected to a bath containing a dispersant of an adhesive modifier (described later) at 100 to 110 ° F (38 to 43 ° C). Dip twice and single-nipping using a rubber roller. The fabric is then dried and cured in a clip tenter frame at 380 ° F. (193 ° C.) for 2 minutes. The fabric thus treated is washed at 160 ° F. (71 ° C.) and thoroughly washed with water at 140 ° F. (60 ° C.). It is squeezed and dried at 325 ° F. (163 ° C.) for 5 minutes.

The adhesive modifier bath mentioned above contains the following in the form of an aqueous dispersion: (1) a mixture of fluoro compounds as a dispersion comprising two interpolymers and one surfactant [the first constituting 1.8% by weight of the bath; The interpolymer is about 75% of the 2-perfluoroalkylethyl ester of methacrylic acid, wherein the 2-perfluoroalkylethyl group is of the general formula C _n F _{2n + 1} (CH ₂ ) _2- (where n is 5 To 11), about 25% 2-ethylhexyl methacrylate, about 0.25% N-methylolacrylamide and about 97-98% 2-hydroxyethyl methacrylate, 2% N-methylolacrylamide And ethylene dimethacrylate 0.1%. The surfactant constituting 0.1% by weight of the bath is the hydrochloride of ethoxylated stearyl amine. Interpolymers are described in US Pat. Nos. 3,282,905 and 3,378,609] and (2) wax-melamine mixtures as dispersants. The wax component, about 1.0% by weight of the bath, is a paraffin wax derived from petroleum having a melting point of about 60 ° C. The melamine component constituting about 1% by weight of the bath is a melamine derivative, wherein the nitrogen present in the ring contains one methoxymethylene group and one -CH ₂ -O-CO-C ₂₁ H ₄₃ group. .

Dispersants for wax mixtures are mixtures of the acetate salt of "Armine" DM-18D with DM-14D, available from Armor Hess Chemicals Company. (3) about 0.1% by weight ethoxylated amine hydrochloride as an interfacial stabilizer (4) about 3% by weight isopropyl alcohol as wetting agent, (5) about 92% by weight water, about 0.8% by weight of the fluorine compound mixture It contains about 0.5% by weight of the wax-melamine mixture.

To produce a rigid composite ply, the fabric is cut into rectangular pieces of about 12 × 15 in (30.5 × 38 cm), and each piece is sprayed with a matrix resin solution, as described below. Matrix resins are available from Reichhold Chemicals, Inc., 10603 White Plains, New York, USA, orthopolyester identified as "Polylite" resin 33-072. to be. 1% by weight of methyl ethyl ketone peroxide is used as a curing accelerator and the resin is diluted to 20% by weight of acetone to obtain a solution suitable for spraying with viscosity.

The lay up of the ply to form the rigid composite test sheet is made by stacking material in the following order: 1/4 inch (6.4 mm) thick aluminum bottom plate, polyester film peel off A separate fabric layer sprayed with about 40% by weight resin, the amount of matrix resin solution to be composited, a polyester film release sheet and a top plate of aluminum having a 1/4 inch thickness. The layup is placed in a press to which a pressure of 18,000 lb / in ² (124 MPa) is applied.

The layup is heated to about 108 ° C. under maintained pressure. Maintain temperature and pressure for 1 hour. It is then cooled to about 28 ° C. and removed from the press. The aluminum top and bottom plates are removed and the composite is trimmed for testing. The number of plies in each composite sample is shown in Table 1.

Carbon testing of rigid composite samples is carried out in accordance with MIL-STD-662D as follows: Place the layup to be tested in the sample mount to secure the layup and to be perpendicular to the path of the test injector. do. The jet is a 17 grain fragment simulation jet (MIL-P-46593) and is propelled from a test weapon capable of firing the jet at different speeds. The first shot for each layup is for the injector velocity, which is evaluated similarly to the trajectory limit V ₅₀ . When the first shot has fully achieved layup penetration, subsequent shots achieve a partial penetration of the layup with the jet velocity below about 50 ft / sec. On the other hand, if the first shot does not penetrate at all or partially penetrate, then the subsequent shots have a speed of about 50 ft / sec or more to achieve complete penetration. After obtaining one partial jet penetration and one full jet penetration, a speed increase or decrease of about 50 ft / sec is used to allow sufficient firing to determine the trajectory limit (V ₅₀ ) for this layup.

The trajectory limit (V ₅₀ ) finds and calculates three or more equal numbers of arithmetic averages of the highest partial penetration velocity and the lowest complete penetration velocity, provided that the difference between the highest and lowest angular velocity is less than 125fe / sec. to be.

The actual resin content of each rigid composite sample is calculated from the known weight of the fibers in the sample and the total weight of the sample (see Table 1).

Composite area density is determined by weighing a sample of known surface area for each rigid composite sample.

As can be seen from Table 1, the trajectory limit (V ₅₀ ) was significantly increased for each rigid composite sample coated with p-aramid reinforcement with an adhesive modifier.

TABLE 1

Example 2

This example describes a further rigid composite product of the present invention with a comparative composite made without the use of an adhesive modifier.

The fabric used in this example is E. children. Poly (p-phenylene terephthalamide) sold under the name Kevlar 29 by DuPont Dnemoir & Company and identified as Style 735.

Style 735 fabric is a 2x2 basket fabric with 1,5000 d yarns and a nominal light and weft density of 35 x 34 and a nominal basis weight of 14 oz / yd ² .

The fabric is refined using the same procedure as used in Example 1 and coated using the same type of solid adhesive modifier as the same method used in Example 1. The nominal resin content is varied from about 10 to about 45 weight percent based on the weight of the fabric. In addition, the large tissue is prepared by the same method as used in Example 1.

A series of examples (using adhesive modifiers) and comparative (without adhesive modifiers) rigid composite test sheets are prepared by varying the number of resin plies and resin content as described in Example 1. There is a series of test sheets and 25 comparative sheets using 5, 9, 19 and 26 plies of the fabrics thus produced and tested, respectively.

A ballistic test is performed and the ballistic limit (V ₅₀ ) is measured for the sheets for each group as in Example 1. Ballistic results are shown in Table II and graphically shown in FIG. 1 for each group. Although there are dispersions expected in the test results, the trajectory limit of rigid composites using adhesive modifiers and containing p-aramid fabrics is based on the use of adhesive modifiers over the entire range of the studied resin content (10 to 45% by weight of the fabric). It is obvious that this is greater than the trajectory limit of the complex.

TABLE 2

Claims (7)

P-aramid continuous filaments coated with about 0.2-5% by weight of a solid adhesion modifier, wherein the coated filaments are embedded in a matrix and tested at a ballistic limit of about 1,000 to 4,000 ft / sec when tested according to MIL-STD-662D. And a composite area density of about 0.4 to 6 lb / fd ² ]. 14. A rigid composite comprising a polyester resin matrix, a phenolic resin matrix, or a polyamide resin matrix. The composite according to claim 1, wherein the filaments constitute 50 to 90% by weight of the composite. The composite of claim 1 wherein the adhesion modifier comprises 2-perfluoroalkyl ethyl ester. The composite of claim 1 wherein the adhesion modifier comprises paraffin wax. The composite of claim 1 wherein the adhesion modifier comprises a mixture of 2-perfluoroalkylethyl ester and paraffin wax. The composite of claim 1 wherein the p-aramid continuous filaments are in woven form. The complex of claim 1 in the form of a ballistic complex.

Images