CN101479558A - Multilayered material sheet and process for its preparation - Google Patents

Abstract

The present invention relates to a multilayer sheet of material comprising a consolidated stack of unidirectional monolayers made of stretched polymers, wherein the stack of two adjacent monolayers The direction of stretching is different. At least one monolayer comprises a plurality of unidirectional strips of stretched polymer aligned in the same direction, wherein adjacent strips do not overlap. The invention also relates to a method for manufacturing said multilayer material sheet and a ballistic resistant article containing said multilayer material sheet.

Description

Multi-layer material board and its manufacturing method

The present invention relates to a multilayer material sheet comprising a consolidated stack of unidirectional monolayers made of stretched polymer, and to a method for the manufacture of said multilayer material sheet. The invention also relates to ballistic resistant articles comprising sheets of multilayer material.

Known from EP 1627719 is a multilayer material sheet comprising a consolidated stack of unidirectional single layers made of stretched polymers. This publication discloses a multilayer sheet comprising a plurality of unidirectional monolayers composed of ultra-high molecular weight polyethylene, substantially free of a bonding matrix, wherein the directions of stretching of two adjacent monolayers in the laminate are different. A single layer in the multilayer material disclosed in EP 1627719 is produced by arranging a plurality of strips of ultra-high molecular weight polyethylene adjacent to each other, wherein adjacently arranged strips are at least partially overlap. Known multilayer materials cannot be fabricated without overlapping portions. Moreover, in order to obtain better anti-ballistic properties, the material sheet in EP1627719A1 is exclusively made of ultra-high molecular weight polyethylene, basically without an adhesive matrix.

Although the multilayer material sheet according to EP 1627719A1 has satisfactory ballistic properties, this property can be further improved.

It is an object of the present invention to provide a multilayer material sheet which has at least similar ballistic properties to known materials and which is easy to manufacture.

The object according to the invention is achieved by providing a multilayer material sheet comprising a consolidated stack of unidirectional single layers made of stretched polymers, wherein in the stack two phases The direction of stretching differs between adjacent monolayers, wherein at least one monolayer comprises at least one unidirectional strip of stretched polymer, each strip comprising a longitudinal edge, wherein immediately adjacent to and along a majority of said longitudinal edge length, the single layers have no overlap or regions of increased thickness. Preferably, immediately adjacent to and along at least 50%, 60%, 70%, 80%, 90% or 95% of the length of the longitudinal edge of said at least one unidirectional strip, there is no overlap or no thickness in said single layer Increased area. Most preferably, there is no overlap or no regions of increased thickness in said single layer along and immediately adjacent the entire length of the longitudinal edge of said at least one unidirectional strip.

The individual layers are formed without overlap or excess binder, which enables the individual layers to be more easily stacked and compressed into a multi-layer sheet of material having a uniform areal density, resulting in more uniform ballistic performance on said multi-layer sheet.

In one embodiment of the invention, the above objects are achieved by a multilayer sheet of material comprising a consolidated stack of unidirectional monolayers, wherein the directions of stretching of two adjacent monolayers in the stack differ, wherein at least one monolayer comprises a plurality of unidirectional strips of stretched polymer aligned in the same direction, and wherein adjacent strips do not overlap.

As a result, the multilayer material sheet according to the present invention, that is, there is substantially no region of increased thickness immediately adjacent to and along the longitudinal edges of the unidirectional strips (for example, substantially no longitudinal strips overlap or are not covered by a large area of overlapping adhesive material). Strips combined together) not only improved the ballistic performance of the sheet, but also to an unexpectedly high degree. Preferably, said single layer is free of regions of increased thickness extending along (not transversely across) and next to the longitudinal edges of the at least one unidirectional strip. the thickness along and immediately adjacent the longitudinal edges of the unidirectional strips as compared to the region of increased thickness caused by the transverse overlap of the unidirectional strips, such as that observed when the unidirectional strips are arranged to form a braided structure The presence of elevated regions makes it more difficult to form a uniform consolidated laminate.

A particularly preferred sheet of multilayer material according to the invention comprises a stack of individual layers, wherein each individual layer consists of a plurality of unidirectional strips made of stretched polymer, arranged in the same direction, and in each individual layer In a layer, adjacent strips do not overlap. The material sheet of the present invention is more uniform than known material sheets. In fact, at overlapping positions, the sheets of material are known to have regions of increased areal density. In the material sheet according to the invention, these regions do not occur or occur to a lesser extent. This feature dramatically improves ballistic performance.

In the multilayer material sheet of the invention, the individual layers are preferably produced by arranging a plurality of strips such that their longitudinal edges are as close as possible to each other, preferably in an abutting manner. However, in order to be able to manufacture monolayers at an economical speed on an industrial scale, gaps between adjacent strips are allowed (ie adjacent strips in a monolayer are not touching along their longitudinal edges, gaps are greater than 0%). Preferably, the sheet of material according to the invention is characterized in that the gap between adjacent strips in a single layer is less than 10% of the width of adjacent unidirectional strips, even more preferably less than the width of adjacent unidirectional strips 5%, and even more preferably less than 3% of the width of adjacent unidirectional strips. Most preferably, the gap between adjacent strips in a single layer is less than 1% of the width of adjacent unidirectional strips.

The sheet of material of this preferred embodiment is easy to manufacture with a similar level of ballistic performance as a sheet of material without gaps. Although the monolayer according to the invention is preferably produced by arranging a plurality of strips next to each other along their longitudinal edges, a monolayer made of only one (sufficiently wide) strip of sufficient width also falls within the It is within the scope of the invention because no regions of increased thickness are present in such a single layer immediately adjacent to and along the length of the longitudinal edge of at least one unidirectional strip.

By arranging a plurality of strips of stretched polymer such that each strip is oriented parallel to an adjacent strip and such that a substantial amount (i.e., at least 90%) of the adjacent strips do not overlap, a material similar to known materials is obtained. Compared to improved ballistic properties. According to the prior art described in EP 1627719 A1, the unidirectional monolayer comprises a plurality of high strength unidirectional polyethylene strips oriented parallel in one plane but partially overlapping, said overlapping area being 5 mm to 40 mm wide. According to another embodiment, a narrow polymeric film with a width of about 5 to 20 mm is placed on the contact area between two adjacent strips. Another advantage of the multilayer material sheet in a preferred embodiment according to the invention is that no additional polymeric film as described above is required in order to obtain good anti-ballistic properties. Furthermore, the use of strips without regions of increased thickness as defined herein, followed by stacking and consolidating multiple individual layers under pressure, results in a multilayer material sheet having a more uniform areal density and thickness than the prior art.

A particularly preferred embodiment of the multilayer material sheet of the present invention is characterized in that the polymer for the manufacture of the multilayer material sheet is selected from polyolefins, polyesters, polyvinyl alcohols, polyacrylonitriles, polyamides (especially poly(p- phenylene terephthalamide)), liquid crystal polymers and ladder polymers (such as polybenzimidazoles or polybenzoxazoles, especially poly(1,4-phenylene-2,6-benzo dioxazole) or poly(2,6-diimidazo[4,5-b-4′,5′-e]pyridine-1,4-(2,5-dihydroxy)phenylene)). Unidirectional tapes and monolayers made from these polymers are preferably highly oriented by stretching various material forms such as films at appropriate temperatures. "Unidirectional strips and monolayers" in the context of this application mean strips and monolayers with polymer chains preferentially oriented in one direction, ie in the direction of stretching. The aforementioned strips and monolayers can be produced by stretching, preferably uniaxially, and have anisotropic mechanical properties.

The multilayer sheet of material of the present invention allows the use of stretched polymers with relatively low strength, thus eliminating the need for ultra-high molecular weight polyethylene to obtain good ballistic performance. However, preferred embodiments of the present invention include ultra-high molecular weight polyethylene. The ultra-high molecular weight polyethylene may be linear or branched, but linear polyethylene is preferably used. Linear polyethylene is here understood to mean polyethylene having less than 1 side chain per 100 carbon atoms, preferably less than 1 side chain per 300 carbon atoms; wherein side chains or branched Usually contains at least 10 carbon atoms. Side chain measurements can suitably be made by FTIR on pressed films of 2 mm thickness, eg as described in EP0269151. The linear polyethylene may further comprise up to 5 mol% of one or more other olefins copolymerizable with ethylene, eg propylene, butene, pentene, 4-methylpentene, octene. Preferably, the linear polyethylene has a high molar mass and an intrinsic viscosity (IV, determined on a solution of decahydronaphthalene at 135°C) of at least 4 dl/g, more preferably at least 8 dl/g, most preferably at least 10 dl/g . The above-mentioned polyethylene is also called ultra-high molecular weight polyethylene. Intrinsic viscosity is a measure of molecular weight which is easier to determine than actual molar mass parameters such as Mn and Mw. Polyethylene films of this type have particularly favorable ballistic properties.

The strips according to the invention can be produced in the form of films. A preferred method for forming the above film or strip comprises feeding polymeric powder between assembled endless belts, compression molding it at a temperature below the melting point of the polymeric powder, and rolling The resulting compression molded polymer is then stretched. Such a method is described, for example, in EP0 733 460 A2, which is hereby incorporated by reference. If desired, the polymer powder may be mixed with a suitable liquid organic compound having a boiling point higher than the melting point of the polymer before feeding and compression molding the polymer powder. Compression molding can also be carried out by temporarily retaining polymer powders between endless belts while conveying them. This can be achieved, for example, by providing compression rollers and/or rollers connected to the endless belt. The UHMWPE polymer used in this method needs to be stretchable in the solid state.

Another preferred method for forming a film comprises feeding a polymer to an extruder, extruding a film at a temperature above the melting point of the polymer, and stretching the extruded polymeric film. If desired, the polymer may be mixed with a suitable liquid organic compound, eg to form a gel, such as is preferred when ultra high molecular weight polyethylene is used, before being added to the extruder.

The resulting film can be stretched, preferably uniaxially, by means known in the art. The method includes extrusion stretching and elongation stretching on a suitable stretching unit. In order to obtain increased mechanical strength and stiffness, multi-step stretching can be performed. In the case of the preferred ultrahigh molecular weight polyethylene film, uniaxial stretching is usually carried out in multiple stretching steps. The first stretching step may include, for example, stretching to a stretch ratio of 3. Multi-step stretching is generally available with stretch ratios of 9 for stretching temperatures up to 120°C, stretch ratios of 25 for stretching temperatures up to 140°C, and stretch ratios of 50 for stretching temperatures up to and above 150°C. Stretch ratios of about 50 or greater can be achieved by performing multi-step stretching at increasing temperatures. This results in high strength tapes, where for ultra high molecular weight polyethylene tapes strengths of 1.50 GPa to 1.8 GPa and higher can be obtained.

The resulting stretched tapes can be used as such to make monolayers, or they can be cut to the desired width, or split along the direction of stretching. Preferably, the single layer is made from unsplit strips. The width of the unidirectional tape thus produced is limited only by the width of the film used to make the tape. The width of the strips is preferably greater than 2mm, more preferably greater than 5mm, most preferably greater than 30mm. The areal density of the strips or monolayers can vary within wide ranges, for example between 5 and 200 g/m ² . Preferred areal densities are between 10 and 120 g/ ^m2 , more preferably between 15 and 80 g/ ^m2 , most preferably between 20 and 60 g/ ^m2 .

In another particularly preferred multilayer material sheet according to the invention, at least one individual layer, preferably all individual layers, is constituted by a plurality of stretched polymer layers arranged to form a textile structure Unidirectional strip composition. The above-mentioned strips can be manufactured by applying weaving techniques, such as weaving, weaving, etc., to small strips of stretched polymers instead of fibers as is usually done. Although in this embodiment the polymeric strips have regions of increased thickness where the strips partially overlap at intersection points, the regions of increased thickness are transverse to the longitudinal edges of the unidirectional strips rather than along and immediately adjacent the longitudinal edges The edges are extended. Each strip (which is a small narrow strip of woven fabric) is arranged so that there is no overlap between adjacent strips aligned in the same direction. Ballistic performance is further improved by stacking the strips in such a way that the seam lines in the different individual layers are interleaved with each other.

In some embodiments, the monolayer may contain an adhesive that is topically applied to bond and stabilize the plurality of unidirectional strips, thereby maintaining the structure of the monolayer during handling and manufacturing of the unidirectional board. Suitable binders are described, for example, in EP 0191306 B1, EP 1170925 A1, EP 0683374 B1 and EP 1144740 A1. The adhesive can be applied in various forms and ways, for example as a transverse adhesive strip (across the unidirectional strip). Applying the adhesive during the formation of the monolayer facilitates the stabilization of the strips, enabling shorter production cycles while avoiding overlapping between adjacent strips.

In one embodiment, the adhesive is applied along the longitudinal edges of the unidirectional strips such that adjacent unidirectional strips are stably in close proximity. Since the function of the adhesive is to temporarily retain and stabilize the plurality of unidirectional strips during handling and manufacture of the unidirectional sheet, topical application of the adhesive is preferred. Localized application of adhesive is application limited to the immediate vicinity of the longitudinal edges and may include intermittent localized applications (dotted application along the longitudinal edges).

Preferably, the adhesive is applied such that the maximum increased thickness (beading) of the monolayer is 150% of the average thickness of the unidirectional tapes forming the monolayer. More preferably, the adhesive is applied such that the maximum increased thickness is 120%, 110% or 105% of the average thickness of the plurality of unidirectional strips forming a single layer. In another embodiment, the adhesive is applied such that the increase in thickness of the individual layer immediately adjacent the longitudinal edges of the unidirectional tape is less than 4 microns, more preferably less than 3, 2 or 1 microns.

In embodiments where adhesive is applied locally intermittently, the proportion of longitudinal edges containing adhesive is preferably less than 50%, 30%, 20%, 10%, 5% or 2%. Similarly, the proportion of the longitudinal edges (or areas immediately adjacent to the longitudinal edges) of the unidirectional tape that are raised due to the application of adhesive is preferably less than 50%, 30%, 20%, 10%, 5% or 2%. Preferably, the binder comprises less than 20%, less than 10%, less than 5%, less than 2%, less than 1%, less than 0.5% or less than 0.2% by weight of a single layer or consolidated laminate.

In other embodiments, joining methods such as ultrasonic welding may be used to fuse together portions of the longitudinal edges of adjacent elastic strips in an intermittent manner.

Adjacent unidirectional strips are maintained in a parallel arrangement for strips of adjacent single layers joined in an intermittent manner along immediately adjacent longitudinal edges in a single layer. The application of adhesive enables the close proximity of adjacent unidirectional strips with substantially no overlap between adjacent longitudinal edges. Local variations in monolayer thickness are advantageously reduced (compared to conventional monolayers with overlapping longitudinal edges or with continuously overlapping narrow strips of polymeric adhesive), which allows the resulting consolidated stack of monolayers to have a more uniform thickness , thus having a more uniform stress distribution.

In principle, the thickness of the individual layers or strips of the multilayer material sheet can be selected within wide ranges. Preferably, however, the multilayer material sheet according to the invention is characterized in that at least one individual layer has a thickness of not more than 120 μm, more preferably not more than 50 μm, most preferably between 5 and 29 μm. Particularly advantageous anti-ballistic properties are obtained if the thickness of all the individual layers in the stack does not exceed 120 μm, more preferably does not exceed 50 μm, most preferably lies between 3 and 29 μm. A further preferred multilayer material according to the invention is characterized in that at least one individual layer has a thickness greater than 10 μm but not more than 50 μm, preferably not more than 100 μm, more preferably not more than 120 μm. By limiting the thickness of at least one of the individual layers in the stack to the claimed thickness, it is surprisingly possible to achieve sufficient ballistic protection even with individual layers of rather limited strength.

The strength of the individual strips in the multilayer material sheet is mainly dependent on the polymer from which these strips are made and the stretch ratio (unidirectional) of these strips. The strength of the tape (and monolayer) is at least 0.75 GPa, preferably at least 0.9 GPa, more preferably at least 1.2 GPa, even more preferably at least 1.5 GPa, even more preferably at least 1.8 GPa, even more preferably at least 2.1 GPa , most preferably at least 3 GPa. The unidirectional monolayers are preferably sufficiently interconnected with each other, which means that the unidirectional monolayers do not delaminate under normal conditions of use (eg room temperature).

The multilayer material sheet according to the invention preferably comprises at least 2 unidirectional monolayers, preferably at least 4 unidirectional monolayers, more preferably at least 6 unidirectional monolayers, even more preferably at least 8 unidirectional monolayers , most preferably comprising at least 10 unidirectional monolayers. Increasing the number of unidirectional individual layers in the multilayer material sheets of the present invention will simplify the process of making articles from these material sheets, such as making ballistic panels.

In one embodiment of the invention there is provided a method for manufacturing a multilayer sheet of material, the method comprising:

(a) disposing at least one first stretched polymeric unidirectional strip on a moving substrate, thereby forming a first monolayer, wherein immediately adjacent to and along most of the length of a longitudinal edge of said at least one unidirectional strip , the monolayer has no regions of increased thickness;

(b) maintaining said first monolayer on said moving substrate;

(c) disposing at least one second stretched polymer unidirectional strip on said first monolayer, thereby forming a second monolayer, wherein said second monolayer is oriented relative to said first monolayer the layers are angled α; and

(d) compressing the laminate thus formed, thereby consolidating its monolayers.

The consolidated monolayer stack has a more uniform thickness/areal density than the prior art because, in the monolayer (preferably in each monolayer), along and next to the longitudinal edge of at least one unidirectional strip The area of increased thickness is reduced or does not exist.

In a preferred embodiment of the invention there is provided a method for manufacturing a panel with the claimed multilayer material. Described method of the present invention comprises the steps:

(a) providing a plurality of strips of stretched polymer, the strips being arranged so that each strip is oriented parallel to an adjacent strip, and adjacent strips do not substantially overlap;

(b) disposing said plurality of stretched polymer strips on a moving substrate, thereby forming a first monolayer;

(c) maintaining said first monolayer on said moving substrate;

(d) arranging a plurality of stretched polymer unidirectional strips on said first monolayer, thereby forming a second monolayer, wherein said second monolayer is oriented relative to said first monolayer angle α; and

(e) compressing the laminate thus formed, thereby consolidating its monolayers.

Step (a) optionally includes the application of adhesives or bonding means to hold or stabilize adjacent strips, thereby increasing the achievable production rate. Multilayer sheets of material substantially free of overlapping regions (ie regions of high areal density) are readily produced using the claimed method. The material sheet thus produced has improved ballistic properties compared to a material sheet with overlapping regions.

Preferably, the plurality of stretched polymer strips are unwound from an unwinding station, and step (d) is performed by at least partially folding the plurality of stretched polymer strips onto themselves. More preferably, the plurality of stretched strips are arranged such that the first single layer is at an angle β with respect to the direction of movement of the substrate and folded such that the fold lines run substantially parallel to the direction of movement of the substrate. The method according to the invention has the further feature that the angle β is between 40 and 50 degrees, most preferably the angle β is about 45 degrees.

Another preferred method according to the invention is characterized in that said second monolayer is at least partially adhered to said first monolayer. This can be easily accomplished, for example, by ultrasonic welding, by adding low-melting films, adhesives, or by other methods of bonding the layers together. The adhesion of the second monolayer to the first monolayer is preferably sufficiently strong that no significant relative movement of the individual strips and/or monolayers occurs during transport of the monolayer assembly.

According to the method of the invention, a multilayer sheet of material is produced, wherein the stretching directions of two adjacent individual layers of the stack differ by an angle α. For the preferred method in which the fold lines run approximately parallel to the direction of movement of the substrate, the angle α=2β. Although the angle α can be chosen within a wide range, it is preferably between 45 and 135°, more preferably between 65 and 115°, most preferably between 80 and 100°. In a further preferred range, the particularly preferred angle α is approximately 90°. The material made according to this preferred embodiment is known in the art as a cross-ply.

The multilayer material sheet according to the invention is particularly suitable for the manufacture of ballistic resistant articles, such as vests or armor plates. Ballistic protection applications include applications against the impact threat of several projectiles, including protection against armor-piercing bullets, so-called AP bullets and hard particles such as shrapnel and shrapnel.

Ballistic resistant articles according to the invention comprise at least 2 unidirectional monolayers, preferably at least 10 unidirectional monolayers, more preferably at least 20 unidirectional monolayers, even more preferably at least 30 unidirectional monolayers, most preferably Consists of at least 40 unidirectional single layers. The stretching directions of two adjacent monolayers in the stack differ by an angle α. The angle α is preferably between 45 and 135°, more preferably between 65 and 115°, most preferably between 80 and 100°.

Preferably, the ballistic resistant article according to the invention comprises other plates of inorganic material selected from ceramics; metals, preferably aluminium, magnesium, titanium, nickel, chromium and iron or their alloys; glass; graphite or combinations thereof. Particularly preferred are metals. In the above case, said metal in the metal plate preferably has a melting point of at least 350°C, more preferably at least 500°C, most preferably at least 600°C. Suitable metals include aluminium, magnesium, titanium, copper, nickel, chromium, beryllium, iron and copper, including alloys thereof, such as steel and stainless steel, alloys of aluminum and magnesium (so-called 5000 series aluminum), aluminum and zinc and magnesium Alloys of aluminum or alloys of aluminum with zinc, magnesium and copper (so-called 7000 series aluminum). The content of such alloys as aluminum, magnesium, titanium and iron is preferably at least 50% by weight. Preferred metal plates include aluminum, magnesium, titanium, nickel, chromium, beryllium, iron (including alloys thereof). More preferably, the metal sheet is based on aluminium, magnesium, titanium, nickel, chromium, iron and alloys thereof. This results in good durability for lightweight ballistic-resistant articles. Even more preferably, the iron and its alloys in the metal plate have a Brinell hardness of at least 500. Most preferably, the metal sheet is based on aluminium, magnesium, titanium and their alloys. This results in the lightest ballistic resistant article with the highest durability. Durability in this application means the lifetime of the composite material under conditions of exposure to heat, moisture, light and UV radiation. While the other material panels may be arranged anywhere within the monolayer stack, preferred ballistic resistant articles are characterized by other material panels being located on the outside of the monolayer stack, most preferably at least on the wounded side of said monolayer stack.

The ballistic-resistant article according to the invention preferably comprises, with a thickness of at most 100 mm, further plates made of the abovementioned inorganic materials. Preferably, the maximum thickness of the other inorganic material sheet is 75 mm, more preferably 50 mm, most preferably 25 mm. This achieves the best balance between weight and ballistic performance. Preferably, where the other inorganic material sheet is a metal sheet, said metal sheet has a thickness of at least 0.25mm, more preferably at least 0.5mm, most preferably at least 0.75mm. This achieves an even better ballistic performance.

In order to improve the adhesion of other inorganic material boards to the multilayer material board, it can optionally be pretreated. Suitable pretreatments for other plates include: mechanical treatment, such as by grinding or grinding to roughen or clean the surface; chemical etching, such as with nitric acid; and lamination with polyethylene film.

In another embodiment of the ballistic resistant article, a bonding layer, such as an adhesive, may be applied between the other sheets and the sheet of multilayer material. The above-mentioned adhesive may include epoxy resin, polyester resin, polyurethane resin, or vinyl ester resin. In another preferred embodiment, the bonding layer may further comprise a woven or non-woven layer of inorganic fibers such as glass fibers or carbon fibers. It is also possible to attach other layers to the multi-layer material board by mechanical means such as screw fastening, bolt fastening and snap fit. In case the ballistic resistant article according to the invention is used in ballistic impact applications where threats against AP bullets, fragments or improvised detonation devices may be encountered, the other plates preferably comprise metal plates covered by a ceramic layer. In this way, a ballistic-resistant article is obtained having a layered structure as follows: ceramic layer/metal layer/at least two unidirectional plates in which the direction of the fibers in the unidirectional plates is at an angle to the direction of the fibers in the adjacent unidirectional plates alpha. Suitable ceramic materials include, for example, aluminum oxide, titanium oxide, silicon oxide, silicon carbide and boron carbide. The thickness of the ceramic layer depends on the level of ballistic impact threat, but typically varies between 2mm and 30mm. Such ballistic resistant articles are preferably arranged so that the ceramic layer is exposed to ballistic impact threats.

In one embodiment of the present invention, there is provided a method for manufacturing a ballistic resistant article, the method comprising: (a) laminating at least 2 monolayers of uniaxially stretched polymers and Sheet of material of titanium, glass and graphite or combinations thereof, each polymeric monolayer comprising at least one unidirectional strip, wherein two adjacent monolayers in said stack have different stretching directions, at least one monolayer along There is no region of increased thickness along and for a substantial length of the longitudinal edge of the at least one unidirectional strip; and (b) consolidating the laminate under temperature and pressure.

In a preferred embodiment of the present invention, there is provided a method for manufacturing a ballistic resistant article, said method comprising the steps of: (a) laminating at least 2 monolayers of uniaxially oriented polymers and materials selected from ceramics, steel, Sheets of other inorganic materials of aluminium, titanium, glass and graphite or combinations thereof, wherein the direction of stretching of two adjacent monolayers in said stack is different, at least one monolayer (preferably all monolayers) comprises a plurality of unidirectional strips of stretched polymer, aligned in the same direction, and adjacent strips do not overlap; and (b) consolidating the laminate under temperature and pressure.

In another method, a laminate of at least 2 uniaxially oriented polymer monolayers is produced in a separate process such as described above. The prefabricated laminate is then combined with plates of other material selected from ceramics, steel, aluminium, titanium, glass and graphite or combinations thereof in step (a) of the method.

Suitable for carrying out the consolidation steps of all the above methods in a hydraulic press. Consolidation means that a single layer is relatively firmly attached to another single layer to form a unit. The temperature of the press is usually used to control the temperature during consolidation. Usually the lowest temperature is chosen to obtain a reasonable rate of consolidation. In this respect, a suitable lower temperature limit is 80°C, preferably this lower limit is at least 100°C, more preferably at least 120°C, most preferably at least 140°C. The selected maximum temperature is below the temperature at which the stretched polymer monolayer loses its high mechanical properties due to, for example, melting. Preferably, the temperature is at least 10°C lower, preferably at least 15°C lower, even more preferably at least 20°C lower than the melting temperature of the stretched polymer monolayer. In cases where the stretched polymer monolayer does not have a defined melting temperature, the temperature at which the stretched polymer monolayer begins to lose its mechanical properties should be read instead of the melting temperature. In the case of the preferred ultra-high molecular weight polyethylene, the selected temperature is below 145°C. The pressure during consolidation is preferably at least 7 MPa, more preferably at least 15 MPa, even more preferably at least 20 MPa, most preferably at least 35 MPa. In this way, an inflexible ballistic-resistant article is obtained. The optimum time for consolidation is usually in the range of 5 to 120 minutes, depending on conditions such as temperature, pressure and part thickness, and can be verified by routine experimentation. In the case of the manufacture of curved ballistic resistant articles it is advantageous to first preform the other material sheets into the desired shape and then consolidate with the single and/or multilayer material sheets.

Preferably, cooling under pressure is also carried out after compression molding at high temperature in order to obtain high ballistic performance. Preferably the pressure is maintained at least until the temperature is low enough to prevent relaxation. This temperature can be determined by one skilled in the art. When manufacturing ballistic resistant articles comprising a monolayer of ultra-high molecular weight polyethylene, typically the compression temperature is in the range of 90 to 150°C, preferably in the range of 115 to 130°C. Typically the compression pressure is in the range of 100 to 300 bar, preferably in the range of 100 to 180 bar, more preferably in the range of 120 to 160 bar. Compression times typically range from 40 to 180 minutes.

The multilayer material panels and ballistic-resistant articles of the present invention are particularly advantageous compared to previously known ballistic-resistant materials because they provide at least the same level of protection as known articles at a significantly lower weight, or at significantly lower weight than known articles Provides improved ballistic performance at equivalent weight. Raw materials are inexpensive and the manufacturing process is relatively short, making it more cost-effective. Since different polymers can be used to manufacture the multilayer material sheet of the invention, the respective properties are optimized according to the specific application. In addition to ballistic resistance, other properties include, for example, thermal stability, shelf life, resistance to deformation, ability to bond with other material sheets, formability, and the like.

The present invention is now further explained by the following FIGS. 1-4 , but the present invention is not limited thereto.

Figure 1 schematically represents an embodiment of a plant for carrying out the method of the invention.

Figure 2 schematically represents a multilayer material sheet.

Figure 3 schematically represents a single layer of textile tape.

Figure 4 schematically represents a multilayer material sheet.

Referring to Figure 1, there is shown an apparatus 1 for manufacturing a multilayer material sheet of the claimed type. The plant comprises means 2 for providing a plurality of stretched polymer strips 10 . The device 2 can comprise, for example, an uncoiler for the coil of polymer strip 10 . The polymer strips 10 are aligned such that each strip 10 is oriented parallel to the adjacent strip 10 . The device 1 also comprises a moving substrate 3 , which in the embodiment shown is a belt driven by two cylindrical rollers 4 . The belt 3 moves in the direction indicated by the arrow at a speed V3. A plurality of strips 10 are arranged on the substrate 3 by passing the strips 10 through a set of nip rollers (5a, 5b). A plurality of strips 10 are held on the substrate 3 by a holding device, for example by perforating the substrate 3 and providing a space 6 which may be brought under vacuum by a pump 7 below the substrate 3 . Behind the movable base plate 3, there is placed a belt press comprising two heating surfaces (21, 22) driven by cylindrical rollers 23

The method according to the invention consists in unwinding a plurality of uniaxially oriented polymer strips 10 from an uncoiler 2 at a speed V1. The strips 10 are arranged such that adjacent strips do not substantially overlap and there is substantially no gap (typically less than 2mm) between adjacent strips. The strip 10 is then provided by a set of nip rolls (5a, 5b). As shown in Figure 1, the combination of the uncoiler 2 and the set of nip rolls (5a, 5b) traverses the substrate 3 back and forth in the transverse direction at a speed V2. The vacuum belt substrate 3 is moved at a speed V3 in a direction substantially perpendicular to the transverse direction. The ratios of V2 and V3 are chosen such that a plurality of strips 10 are arranged on the moving substrate 3 at an angle of about 45 degrees relative to the direction of movement of the substrate 3, forming a first monolayer. Said first monolayer is held on the moving substrate 3 by suction generated by vacuum means (6, 7). When the uncoiler 2 reaches the other side of the moving substrate 3, reverse its moving direction, and move the uncoiler 2 in the opposite direction. Thereby, the plurality of stretched polymer strips 10 are at least partially folded upon themselves. More specifically, a plurality of stretched polymer strips 10 are folded such that the fold lines extend approximately parallel to the direction of movement of the substrate 3 . Thereby, a second monolayer is arranged on said first monolayer, wherein said second monolayer is oriented at an angle of approximately 90 degrees with respect to said first monolayer. In order to ensure that the assembly of the first monolayer and the second monolayer can be transported without relative movement of the individual strips and/or monolayers, the second monolayer of strips is at least partially adhered to the first monolayer superior. Suitable means for use in the above steps include, but are not limited to, ultrasonic welding, addition of low-melt films, adhesives, hot melts, or any other method of bonding the layers together.

Finally, the monolayer assembly thus formed is fed onto a belt press or calender 20 for final consolidation of the multilayer material sheet. In the belt press or calender 20, the stacked plurality of strips is bonded at a temperature close to the melting point of the strips. In the described embodiment, the resulting multilayer material is a cross-folded two-layer material made of strips, wherein the direction of the strips is at an angle of about 45 degrees relative to the direction of movement of the substrate 3 .

×多层材料的宽度。The width of the plurality of strips 10 on the device 2 is determined by the width of the multilayer material placed on the substrate 3 on a belt press or calender, reference 20 . In the case where the angle β formed by the strips with respect to the moving direction of the substrate 3 is 45 degrees, the width of the plurality of strips 10 is equal to

× the width of the multilayer material.

Referring to Figure 2, there is shown a diagrammatic representation of a multilayer material sheet comprising a consolidated stack of 2 unidirectional monolayers made of stretched polymer in accordance with the present invention, wherein, The direction of stretching of two adjacent monolayers in a laminate is rotated by 90 degrees, wherein each monolayer comprises a plurality of unidirectional strips of stretched polymer aligned in the same direction, and wherein adjacent strips do not overlapping. For clarity, the individual strips extend at the edges of the multilayer material sheet.

Referring to Figure 3, there is shown a diagrammatic representation of a single layer according to the present invention, wherein said single layer is composed of a plurality of unidirectional strips of stretched polymer arranged to form a textile structure.

Referring to Figure 4, there is shown a diagrammatic representation of a multi-layer material sheet according to the present invention, said multi-layer material sheet comprising the Figure 3 single layer (indicated by solid lines) indicated by reference number 1, and the textile layer indicated by reference number 2 below it. The second monolayer of the strip (dashed line). The second individual ply is arranged such that the seam lines of the individual individual plies are arranged in a staggered manner relative to each other.

The test methods involved in this application are as follows:

According to the method PTC-179 (Hercules Inc. Rev. Apr. 29, 1982) to measure the intrinsic viscosity, the test conditions are: at 135 ℃, in decahydronaphthalene, the dissolution time is 16 hours, and the dosage is 2g/l solution DBPC was used as an antioxidant, where the viscosities measured at different concentrations were extrapolated to give the viscosity at zero concentration.

Tensile properties (measured at 25°C): According to ASTM D885M, the tensile strength (or tenacity) of multifilament yarns is defined and determined using fibers with a nominal nominal length of 500mm and a crosshead speed of 50%/min ), tensile modulus (or modulus) and elongation at break (or eab). The modulus was determined from the slope between 0.3-1% strain on the basis of the measured stress-strain curve. To calculate the modulus and strength, the measured tensile force was divided by the titer, which was determined by weighing a 10-meter length of fiber; values in GPa were calculated assuming a density of 0.97 g/ ^cm3 . Tensile properties of films were determined according to ISO 1184(H).

Claims (32)

1. multilayered material sheet, described multilayered material sheet comprises a fixed folded one-way single-layer of being made by strained polymer, wherein, the draw direction difference of two adjacent monolayer in the described lamination, wherein at least one individual layer comprises the unidirectional tape that at least one is made by strained polymer, each band comprises longitudinal edge, next-door neighbour and wherein along most of length of the described longitudinal edge of described at least one unidirectional tape, and described individual layer does not have areas of elevated thickness.

2. multilayered material sheet as claimed in claim 1, wherein, described areas of elevated thickness is than at least 4 microns of the thickness height of described at least one unidirectional tape.

3. multilayered material sheet as claimed in claim 1, wherein, described areas of elevated thickness is than the thickness height at least 50% of described at least one unidirectional tape.

4. as any described multilayered material sheet in the claim 1 to 3, wherein, along and the whole length that is close to the described longitudinal edge of described at least one unidirectional tape, described at least one individual layer does not have areas of elevated thickness.

5. as any described multilayered material sheet in the claim 1 to 4, wherein, described at least one individual layer is made of a plurality of unidirectional tape of being made, being arranged with equidirectional by strained polymer, and wherein adjacent band is not overlapping.

6. multilayered material sheet as claimed in claim 5, wherein, described at least one individual layer comprises a plurality of unidirectional tape of being made by strained polymer, wherein, the gap between the adjacent ribbons is less than 10% of the width of adjacent unidirectional tapes.

7. multilayered material sheet as claimed in claim 6, wherein, the gap between the adjacent ribbons is less than 5% of the width of adjacent unidirectional tapes.

8. multilayered material sheet as claimed in claim 5, wherein, the longitudinal edge of described adjacent ribbons each other to small part near.

9. multilayered material sheet as claimed in claim 8, wherein, described adjacent ribbons is close to each other at least partially stabilizedly.

10. any described multilayered material sheet in the claim as described above, wherein, the thickness of at least one individual layer can be above 100 microns.

11. multilayered material sheet as claimed in claim 10, wherein, the thickness of at least one individual layer can be above 29 microns.

12. as claim 10 or 11 described multilayered material sheets, wherein, the thickness of described at least one individual layer is greater than 10 microns.

13. any described multilayered material sheet in the claim as described above, wherein, the intensity of at least one individual layer is 0.9GPa at least.

14. multilayered material sheet as claimed in claim 13, wherein, the intensity of at least one individual layer is 1.5GPa at least.

15. any described multilayered material sheet in the claim as described above, wherein, described polymer is selected from polyolefin; Polyester; Polyvinyl alcohol; Polyacrylonitrile; Polyamide, especially poly-(right-the phenylene terephthalamide); Liquid crystal polymer and scalariform polymer, such as polybenzimidazoles or polybenzoxazole, especially poly-(1,4-phenylene-2,6-Ben Bing Er oxazole) or poly-(2, the 6-diimidazole also [4,5-b-4 ', 5 '-e] pyridine-1,4-(2, the 5-dihydroxy) phenylene).

16. multilayered material sheet as claimed in claim 15, wherein, described polyolefin comprises ultra-high molecular weight polyethylene.

17. a method that is used for making any described multilayered material sheet of claim 5 to 16, described method comprises:

(a) provide a plurality of drawn polymer tapes, arrange described band so that each band and adjacent ribbons are parallel-oriented, and adjacent ribbons is not overlapping;

(b) described a plurality of drawn polymer tapes are arranged on the moving substrate, thereby form first individual layer;

(c) described first individual layer is remained on the described moving substrate;

(d) a plurality of strained polymer unidirectional tape are arranged on described first individual layer, thereby form second individual layer, wherein, the direction of described second individual layer is with respect to the angled α of described first individual layer; And

(e) compress the lamination that forms thus, thereby make its single-layer, consolidated.

18. method as claimed in claim 17, wherein, step (a) further comprises, adhesive or adhesive means are applied to step on the adjacent ribbons.

19. as claim 17 or 18 described methods, wherein, described a plurality of drawn polymer tapes are untied from uncoiler, by carrying out step (d) on himself with described a plurality of drawn polymer tapes are partially folded at least.

20. as claim 17,18 or 19 described methods, wherein, described a plurality of drawn polymer tapes are arranged, thereby make described first individual layer, thereby and fold and make the moving direction almost parallel ground of broken line and described substrate extend with respect to the angled β of the moving direction of described substrate.

21. method as claimed in claim 20, wherein, described angle beta is between 40 to 50 degree.

22. as any described method in the claim 17 to 21, wherein, described second individual layer to small part adheres on described first individual layer.

23. a method that is used to make ballistic-resistant article, described method comprises:

(a) stacked at least 2 simple tension polymer monolayers and the plate of material that is selected from pottery, steel, aluminium, titanium, glass and graphite or its combination, the draw direction difference of two adjacent monolayer in the lamination wherein, at least one individual layer comprises a plurality of strained polymer unidirectional tape of arranging along equidirectional, and adjacent ribbons is not overlapping; With

(b) fixed laminated plate under uniform temperature and pressure.

24. a ballistic-resistant article, described ballistic-resistant article comprise any described multilayered material sheet in the claim 1 to 16.

25. ballistic-resistant article as claimed in claim 24, described ballistic-resistant article comprises at least 40 one-way single-layers.

26. as claim 24 or 25 described ballistic-resistant articles, described ballistic-resistant article comprises other inorganic material plate, described inorganic material is selected from pottery, steel, aluminium, magnesium, titanium, nickel, chromium and iron or their alloy, glass and graphite or its combination.

27. ballistic-resistant article as claimed in claim 26, wherein, other inorganic material plate is positioned at the outside of single layer stack, is positioned at the surface of a wound that is subjected to of described single layer stack at least.

28. as claim 26 or 27 described ballistic-resistant articles, wherein, the thickness of described other inorganic material plate is 50mm at the most.

29. as any described ballistic-resistant article in the claim 26 to 28, wherein, have binder course between any described plate of material in other inorganic material plate and the claim 1 to 16, described binder course comprises the textle layers or the nonwoven layers of inorfil.

30. a method that is used for making any described multilayered material sheet of claim 1 to 16, described method comprises:

(a) at least one first strained polymer unidirectional tape is arranged on the moving substrate, thereby forms first individual layer, wherein, next-door neighbour and along most of length of the longitudinal edge of described at least one unidirectional tape, described individual layer does not have areas of elevated thickness;

(b) described first individual layer is remained on the described moving substrate;

(c) at least one second strained polymer unidirectional tape is arranged on described first individual layer, thereby forms second individual layer, wherein, the direction of described second individual layer is with respect to the angled α of described first individual layer; And

(d) compress the lamination that forms thus, thereby make its single-layer, consolidated.

31. a method that is used to make ballistic-resistant article, described method comprises:

(a) stack at least 2 simple tension polymer monolayers and the plate of material that is selected from pottery, steel, aluminium, titanium, glass and graphite or its combination, each individual layer comprises at least one unidirectional tape, the draw direction difference of two adjacent monolayer in the wherein said lamination, and wherein, next-door neighbour and along most of length of the longitudinal edge of described at least one unidirectional tape, at least one individual layer does not have areas of elevated thickness; With

(b) fixed laminated plate under uniform temperature and pressure.

32. as any described multilayered material sheet in the claim 1 to 16, wherein, at least one individual layer comprises a plurality ofly makes, arranges the unidirectional tape that forms textile fabric by described strained polymer.

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