MXPA98003456A - Microstructured articles with support and fabricac methods - Google Patents

Abstract

The present invention relates to microstructured articles of the invention comprising in order: a) a microstructured member, b) a sealing layer melt-bonded to the microstructured member and c) a backing member. The backing member is a fibrous mesh comprising a plurality of multifilament strips and is melt bonded to the second surface of the sealant layer.

Description

ARTICLES MICROSTRUCTURED COH BACKUP AND MANUFACTURING METHODS FIELD OF THE INVENTION The invention relates to microstructured articles (eg, retroreflective metal sheets of the cubic corner type) with support members.

BACKGROUND OF THE INVENTION Retroreflective visible articles (for example, retroreflective articles based on microspheres and of the cubic type or prismatic type) have been developed to be used for the purpose of increasing safety and visibility, especially during periods of reduced visibility. A variety of cube-corner shapes with several -geometries have been revealed. The above has been developed with the purpose of covering the cubic corner elements - with a sealing layer to maintain an effective retroreflective operation. See, for example, the US Patent. No. 4,025,159 (McGrath).

It is desirable that a retroreflective article adhere to a desired substrate for the useful life of the substrate, or even REF: 27287 that you want an intentional deletion of it. There have been difficulties in connection with the clamping of retroreflective sheet metal to polymeric substrates - flexible, such as monomerically coated polyvinyl chloride ("PVC") coating structures, without interfering with service life and operation. of the substrates. The articles which use materials with polymer-based coating or polymer-based sealing structures, such as the tarpaulins of a trailer and -some signs in spiral form, characteristically- have a duration of about three years. five years, and - up to about ten years. Spiral signs are often used by road construction crews to designate work zones, road hazards, and the like. Vehicle covers with polymer-based coating structures are particularly convenient, allowing the vehicle operator to gain access from the inside of the trailers in a quick and convenient manner, and to maintain a reasonable weather resistance. The vehicle operator can open and close the structured deck many times each day. Therefore, the cover should be flexible but resistant. Polymer-based shell and polymer-based sealing structures should preferably withstand severe weather conditions, as well as the mechanical demands placed on them by the vehicle operator (in the case of tarpaulins of trailers) and by workers of some construction (in the case of signs in the form of a spiral). Trailer covers and spiral signs can be found with extremes in relation to temperature, chemical changes caused by air pollution and salt on the road, as well as by photo-reaction involving infrared, visible and ultraviolet radiation from of sunlight. A retro-reflective metal sheet fastened to such a device, preferably should remain flexible and weather-resistant for the entire expected life of the article.

Many polymer-based and polymer-based sealing materials comprise a layer of interlaced structure of polyester, nylon, or cotton, coated or sealed, on one or both of its major surfaces, with a polymer preferably adapted to the desired use. A commonly used polymer is highly monomerically plastified PVC. Highly plasticized monomeric PVC is durable and convenient in relation to its handling, since it is usually fusible to itself or with some other polymer compatible with the use of heat or by radiofrequency (RF) welding. The large structure materials re-dressed with PVC, are manufactured by small welding panels together. Structured materials coated with damaged or broken PVC are often repaired while it is still on the vehicle.

Among the problems that arise when trying to form a sustainable retroreflective article (measured by the T-peel test or other similar methods) by the fusion of a retroreflective metal sheet made of polymeric materials which are incompatible (from the view of being unable to form a strong and durable fusion) with materials typically used for tarpaulins of trailers or spiral signs, such as monomerically plasticized PVC and copolymers of ethylene and comonomers (such as acrylic acid). vi-nyl acetate). An example of a pair of materials that are com- patible in relation to fusion is highly plasticized PVC and polyurethane. An example of a pair of materials that exhibit incompatibility in relation to - fusion, is highly plasticized PVC and polycarbonate (a material frequently used in retroreflective metal sheets), due to the substantially high melting temperature of polycarbonate . Another example of a pair of materials that present incompatibility in relation to the fusion, is the highly plasticized PVC and the acrylic linked with cubic corners. Monomeric plasticizers present in tarpaulins typically weaken the melt and cause loss of cohesive strength.

RF welding achieves the fusion of polymeric materials through the presence of polar groups converting the radiofrequency energy ("RF") into kinetic movement, which heats the polymer. When a -radio-frequency field is applied to a thermoplastic polymer which has pendant polar groups, the ability of the -polar groups to deviate the orientation in phase with the radiofrequency, determines the degree to which the RF energy is absorbed and converted. in kinetic movement of the polar group. This kinetic energy is conducted as heat to the polymer molecule; If enough RF energy is applied, the polymer will heat up enough to melt. A useful measure to determine the degree to which a polymer will absorb the energy from an alternating field is the ratio of the dielectric constant of the polymers and the dielectric dissipation factor known as the loss factor, which is given by the following relationship: N = 5.55 x 10"13 (f) (£ 2) (K) (tan $) (1) 3 where N is the electrical loss in watts / centimeter -second 3 ("watts / cm-sec"), f is the frequency in Hertz / sec, £ is the field strength in volts / cm, K is the dielectric constant, Gamma is the loss angle, and tan of Gamma is the dissipation factor.

The dissipation factor is the radius of power in-phase to power out of phase. If the polar groups in a thermoplastic polymer have a relative inability to change the orientations in the RF field, these results in a delay phase are known as the dissipation factor. The highest dissipation factor and the largest amount of heat will generate an RF field. Several studies with thermoplastic polymers and with radiofrequency welding have shown that thermoplastic polymers with dissipation factors of approximately 0.065 or larger can form useful bonds. For example, PVC has a dissipation factor of approximately 0.09 to 0.10 at 1 MHz, the nylon filter has a dissipation factor of 0.06 to 0.09, and the polycarbonate has a dissipation factor of -0.01 only at the same frequency . The dielectric constants for these three compounds are 3.5, 6.4, and 2.96 respectively, at 1 MHz.

Polyethylene, polystyrene, and polycarbonate, have very low dissipation factors, and in practical applications present a poor radiofrequency welding capacity.

Polyvinyl chlorides, polyurethanes, polyamides, and polyesters have reasonably high dissipation factors, and have been found, in practical uses, to form highly functional RF bonds. Reference is made to the article "RF Welding of PVC and Other Thermoplastic Compounds" by J. Leighton, T. Brantley, and E. Szabo in ANTEC 1992, p. 724-728. These authors did not attempt to attach the polycarbonate to the other polymers, since it is understood in the art that a useful bond, using RF energy, will always fail in its attempt to form or join.

Only those polar groups within the RF field will start moving and thus undergo heating. In addition, RF fields can be applied in well-defined areas or fields compared to thermal-heat application methods. As a result, RF welding techniques can be used to easily achieve fusions in desired locations with a small need to apply thermal insulation.

PCT Application No. WO 93/10985 (Oppenhejm), published June 10, 1993, discloses the joining of PVC retroreflective articles to a tarpaulin fabric coated with PVC using RF welding. This composite article can then be hot air fused to a vehicle cover with tarpaulin also coated with PVC. To thermally bond the PVC coated fabric to the tarred tarpaulin coated with PVC, the two surfaces are heated with air at about 400 ° C - 600 ° C, and then the surfaces are pressed together to achieve air fusion hot. The purpose of the intermediate coupling of the tarpaulin fabric is to provide a thermal insulation between the hot air and the retroreflective article attached to the tarpaulin fabric to prevent thermal fusion, loss of retroreflection, and destruction of the retroreflective article. .

A product commercially available through Reflexite Corporation, with the alleged designation 393-2457-372, consists of a cubic corner retroreflective metal sheet with cubic corners of PVC and cubic corners fused to the PVC cladding structure. Retroreflective items with cubic corners with cubic corners -constructed of PVC, have relatively low coefficients of retroreflectivity, generally in the order of 250 candela / lux / square meter or less to lighten the colorless metal sheets.

Application WO 94/19711 (Martin et al.) Discloses a retroreflective structure consisting of a layer of transparent prisms formed on a substrate, such as an alkylated tarpaulin. The prisms are made retroreflective by a metallic coating, such as aluminum, gold, or silver. A method for making such a retroreflective structure is also disclosed.

The assignees of European Patent Application EP-A-372727 (Bacon) disclose a sheet of retroreflective metal consisting of a monolayer of retroreflective elements partially fixed in an elastomeric support layer. At least, the support layer of the support layer is a vulcanized or curable elastomer and partially fixed to the back portion of the support layer is an all-directional elastic reinforcement fabric.

The assignees of the US application. with Series Nos. 08 / 236,339 dated May 2, 1994, and 08 / 434,347 dated May 2, 1995, describe an article -retroreflexive of high clarity, flexible and durable that consists of a retroreflective layer type cubic corner polymer with a polymeric compatibilizing layer for bonding to a flexible polymer-based coating structure material. The retroreflective metal sheet comprises, in order: a cubic corner polymer retroreflective layer, a polymeric compatibilizing layer, and a flexible polymeric coating structure, wherein the coating structure -poses a non-compatible polymer cover on each major surface. Therefore, in these constructions there is always at least one non-compatible polymer layer between the structure and the retroreflective layer. The compatibilizing layer is a polymeric material with suitable characteristics to be used both in the retroreflective layer and in a polymer-based coating structure material or in a polymer-based sealing structure under conditions of high-frequency welding and / or thermal dispersion welding. All methods for making these retroreflective articles involve the addition of an independent polymer-based coating structure with the portion of the structure completely submerged on both major surfaces with a non-compatible polymer., to subsequently heat or RF weld all three layers together. The use of an independent polymer compatibilizing layer and a non-compatible coating structure layer increases the cost as well as the thickness of such articles, so it tends to reduce its flexibility and generate soft articles with a larger bending radius . Therefore, it is highly desirable to produce retroreflective articles which do not degrade in relation to their retroreflectivity or adherence of the retroreflective layer to the substrate over time, remaining flexible in virtue of decreasing their thickness; it is also preferred that these articles be less expensive and easier to process.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides flexible microstructured articles with support members. In a characteristic embodiment, the article is retroreflective of the cubic type. The support member provides the desired reinforcement and protection to the microstructured member, and in some embodiments provides means to secure the article to the desired substrate. The articles of the invention can present surprising combinations of flexibility, durability and low cost that are desired.

In summary, the microstructured articles of the invention consist of: (a) a microstructured member comprising (1) -a main layer and (2) a microstructured layer consisting of a series of microstructured elements, wherein at least one of the microstructured elements, as well as the portion of the main layer closest to the microstructured layer, consists of a first polymer (sometimes referred to herein as a first functional linker polymer); (b) a sealing layer with first and second surfaces and consisting of a second polymer (sometimes referred to herein as a second functional bonding polymer) placed on at least the first surface thereof, and - wherein at least one portion of the first surface of the sealing layer is fused to the portion of the first polymer of the microstructured member; Y (c) a support member; the support member - consisting of a fibrous membrane comprising a plurality - of multifilament strands consisting of a third polymer (sometimes referred to herein as a third functional linker polymer) and with a first and second sides; The first one of the membrane is fused to the second surface of the sealing layer. As mentioned above, the support member may optionally consist of an encapsulant member in the form of a strand (sometimes referred to herein as a binder layer). By "functional binding polymer", it is understood that the polymeric member in question has some additional function to that of binding to another member, as indicated herein. For example, in some embodiments the microstructured elements may consist of polycarbonate, and in use the polymer provides the necessary dimensional stability, as well as the refraction and reflection of the desired light.

The polymeric sealing layer is a film or sheet that maintains itself and imparts certain properties of tensile strength and tear resistance that are reflected in the article, while protecting the microstructured elements from contact undesirable with external agents. In both embodiments, the polymer in question has an additional function to that of merely providing adhesion to some other member. An adhesive polymer that serves only to join two or other members together, will not be considered as a functional binding polymer.

The fibrous membrane in the support member is made of a plurality of multifilament strands which, as discussed above, are not saturated with encapsulant resin. As a result, the individual strands remain more flexible and the membrane, as well as the resulting article, exhibit greater flexibility and a greater tear resistance.

In some embodiments, the invention provides retroreflective articles useful in numerous applications, for example, but not limited to, its use in safety garments, fashion or accessories such as a personal bag, its use in pet articles and Other animals, as well as their use in signs such as signs in spirals and signs, flexible vehicle covers, tarpaulins, danger signs, and visible signs. These materials may also be useful in decorative and structural canvases or belts to exhibit graphic designs and logos, as well as to provide same arrangements that may be attached to such articles. The articles of the invention can, up to now, provide combinations-unattainable in relation to high flexibility and conformability, resistance to tearing, resistance to traction, as well as cohesive durability.

Summing up briefly, the method of the invention - understands: (a) a microstructured member consisting of (1) -a main layer and (2) a microstructured layer consisting of a series of microstructured elements, wherein at least one of the microstructured elements, as well as the portion of the main layer closest to said microstructured layer, they comprise a first polymer; Y (b) a sealing layer having a first and second surfaces and consisting of a second polymer; further, by fusing at least a portion of the first surface of the sealing layer to the first polymer portion of the microstructured member; (c) a support member, wherein said support member comprises a fibrous membrane comprising a plurality of multifilament strands consisting of a third polymer and having first and second sides; Y (d) fusing the first side of the membrane to the second surface of the sealing layer.

BRIEF DESCRIPTION OF THE FIGURES The invention will be further explained with reference to the figures, wherein: Figures la-d are cross-sectional views of various constructions illustrative of retroreflective layers known in prior art and which can be used herein as microstructured members; Figure 2 is an end view of an illustrative multifilament strand in a support member of the invention; Figures 3 and 4 are cross-sectional views of a portion of an article of the invention during merging; Figure 5 is a cross-sectional view of a step during high-frequency bonding to produce a retroreflective article of the invention; Figure 6 is a cross sectional view of a step during thermal coupling to produce a retroreflective article of the invention; Figure 7 is a plan view which describes a surface of a representative embossed cylinder useful in the method illustrated in Figure 6; Y Figures 8a and 8b are cross-sectional views of junctions between the sealing layer and two different microstructured members of two illustrative embodiments of the invention.

These figures, which are idealized, are not found on a scale and are projected for merely illustrative and not limiting purposes.

DETAILED DESCRIPTION OF ILLUSTRATIVE INCORPORATIONS As summarized above, the microstructured articles of the invention consist of, in order: (a) a microstructured member consisting of (1) a main layer and (2) a microstructured layer consisting of a series of microstructured elements, wherein at least one of the microstructured elements, as well as the portion of the layer closest to the microstructured layer, consist of a first polymer; (b) a sealing layer having a first and second surfaces and consisting of a second polymer placed on at least the first surface thereof; likewise, at least a portion of the first surface of the sealing layer is fused to at least a portion of the first polymer of the microstructured member; Y (c) a support member, wherein the support member comprises a fibrous membrane consisting of a plurality of multifilament strands consisting of a third polymer and having first and second sides; the first side of the membrane is coupled to the second surface of the sealing layer. The fibrous membrane, in the support member, is constituted by a plurality of multifilament strands which are substantially unsaturated with encapsulating resin.

As used herein, the term "microstructured member" refers to a member that consists of a main layer and a microstructured layer. The main layer can be made from a single layer or from a composite with more than one layer. Characteristically, the main layer has the function of protecting. to the microstructured article of the environmental elements and / or to provide significant mechanical integrity to the microstructured member. The microstructured layer is placed on one side of the main layer. The microstructured layer consists of a series of elements - microstructured, for example, cube corner elements that provide retroreflective properties, and may optionally consist of a layer that can be spliced or linked to the microstructured elements. In a characteristic identical process, the series of elements are joined together by a layer of the same material as the elements which are sometimes referred to as a layer of earth. In some embodiments of the invention, the ground layer and the main layer are the same member; in other embodiments, these will be different layers of the same or different layers of different materials that are bonded together.

The microstructured member will be selected, in large part, based on the desired properties of the resulting article. Illustrative examples include surfaces having a series of cube corner elements protruding from said surfaces, as in the case of retroreflective articles and surfaces having a series of parallel protrusions protruding from the surfaces, as in the case of some products optical As will be understood by those skilled in the art, other microstructured surfaces can be used in the articles of the invention as much as desired.

Figures la-d represent various constructions of retroreflective layers known in prior art, which may be used in some embodiments of the present invention if desired.

In Figure la, the microstructured member 20 is a single layer retroreflective member consisting of a ground layer 22 and a microstructured layer 24 having a plurality of projections in the shape of a cubic corner.

In Figure lb, the microstructured member 26 is a composite retroreflective article consisting of a layer -main 28, as well as a microstructured layer 30. In some embodiments, the polymeric materials used for the main layer 28, as well as the microstructured layer 30, are different. In a preferred example of this embodiment, the main layer 28 is polyurethane and the microstructured surface 30 is cubic polycarbonate screen projections.

In Figure 1, the microstructured member 32 consists of (1) a microstructured layer 32 comprising microstructured e-lements 36 and earth 34, as well as (2) a main layer 38.

In Figure Id, the microstructured member 40 consists of a microstructured layer 43 and a main layer 41. The main layer 41 consists of multiple layers 46 and 48. In a preferred embodiment, the layer 46 is a structural cover and the layer 48 It is a protective coat. The microstructured layer 43 consists of a layer of earth 42 and of microstructured elements 44.

Those skilled in the art will be able to select suitable main layers, as well as microstructured layers for particular applications.

In some preferred retroreflective embodiments of the invention, the microstructured member is a retroreflective sheet metal of the highly flexible cubic corner type. An illustrative example suitable for use herein is the metal laminate disclosed by the Proponents of European Patent Application No. 94.931935.4 (Bacon et al.) Dated October 20, 1994, via the PCT Application No. US94 / 11945. This application discloses adjustable metal sheets consisting of a plurality of discrete corner segments -cubic which are conformably joined together, wherein each cubic corner segment comprises a main portion having a major surface with a front substantially planar, as well as at least one minute retroreflective element of cubic corner projected backward from the main portion and defining one side of the ski point, cubic na of the cubic corner segment. Another illustrative metal sheet suitable for use herein is the flexible metal sheet disclosed in European Patent Application No. 95.900384.9 (Benson et al.), Dated October 20, 1994, via the Application for PCT No. US94 / 11940. This sheet metal consists of: a) a two-dimensional series of cubic corner e-elements of substantially linked and independent, wherein the series comprises a first polymeric material, and b) a cover film having two main surfaces and consisting of a second polymeric material, wherein the series is coupled to the first principal surface of the cover film. In these embodiments, the sealing layer is formed in contact with the cover film between the cube corner elements, and is fused to the cover film.

Those skilled in the art will be able to easily select these and other microstructured members suitable for use in accordance with the present invention.

The polymer of the microstructured elements is selected in relation to the desired properties of the resulting article, the means used to form the microstructured characteristics, the adhesion to the second polymer of the sealing layer, as well as the nature of any other component (s). ) of the microstructured member. The polymer can be a thermoplastic or thermosetting resin as long as it is desired.

In the retroreflective incorporations of the invention, the microstructured member preferably has a high retroreflective luminosity, that is, it has a high retroreflectivity coefficient. Retroreflectivity of the metal sheets expressed as the Retroreflection Coefficient, R, in units of candelas / lux / square meter, is determined using the standardized test ASTM E 810-93b. Typically, the retroreflective incorporations of the invention exhibit a retroreflectivity coefficient of at least about 250, preferably larger than about 400, and more preferably larger than about 600 candelas / lux / square meter at an angle of observation of 0.2 ° and with an input angle of -4 ° for an average of the orientation angles of 0 ° and 90 °. Such criteria in relation to a rigorous luminosity preclude PVC cubic corner elements from being inadequate, due to the inability of PVC to provide a high coefficient of retroreflectivity for any time. This is mainly due to the use of the monomeric plasticizers within the PVC of the retroreflective layer, as well as the fact that the PVC materials are not sufficiently dimensionally stable.

Several factors are important to achieve a high retroreflective luminosity. For example, the polymer that forms the microstructured surface must be substantially optically clear (it can be colored as much as desired) if the sealing layer is fused to the surface or not. Also, the polymer must form cubic corner elements that are dimensionally stable so that the desired geometry is accurate for the purpose of maintaining retroreflection.

The polymeric materials useful for the microstructured member of the present invention are preferably capable of tranting at least 70 percent incident light on the polymer at a given wavelength for ranges of wavelengths from about 400 to about 700. nanometers More preferably, the polymers exhibit a transibility of light greater than 80 percent, and more preferably greater than 90 percent in the range of the wavelengths contemplated above.

Illustrative examples of thermoplastic polymers that can be used as the first functional binding polymer in the microstructured members of the invention, include acrylic polymers such as poly (methyl methacrylate); polycarbonates; cellulosics; polyesters such as poly (butylene terephthalate); poly (ethylene terephthalate); fluoropolymers; polyamides; polyetherketones; poly (etherimide); polyolefins; poly (styrene); poly (styrene) copolymers; polysulfone; urethanes, including aliphatic and aromatic polyurethanes; and blends of the aforementioned polymers such as combinations of poly (ester) and poly (carbonate), as well as combinations of an acrylic polymer and a fluoropolymer. For example, some heat-resistant thermoplastic aliphatic urethanes that may be used herein are disclosed in U.S. Pat. No. 5,117,304 (Huang et al.).

Other illustrative materials in relation to the polymer include reactive resin systems capable of being linked by a free radical polymerization mechanism by actinic radiation and / or by particle radiation, for example, electron irradiation, ultraviolet light, or light. visible. Additionally, these materials can be polymerized by thermal means with the addition of a thermal initiator such as benzoyl peroxide. The radiation-activated cationic polymerizable resins can also be used.

Suitable reactive resins for forming the microstructured layer and for use as the first functional binding polymers may include combinations of the photoinitiator, as well as at least one compound bearing an acrylate group. Preferably, the resin combination contains a monofunctional, difunctional, or polyfunctional compound to ensure the formation of a polymeric mesh linked after the irrationality.

Illustrative examples of resins suitable to be used herein, and which are capable of being polymerized by a free radical mechanism, include acrylic-based resins derived from epoxies, polyesters, polyethers, and urethanes, ethylenically unsaturated compounds, aminoplast derivatives having at least one pendant acrylate group, isocyanate derivatives having at least one pendant acrylate group, epoxy resins or other acrylated epoxies, as well-as mixtures and combinations thereof. The term acrylate is used here to encompass both acrylates and methacrylates. The U.S. Patent No. 4,576,850 (Martens), discloses examples of linkable resins that can be used in forming the peaks of the retroreflective layer of the present invention.

The ethylenically unsaturated resins which are useful herein include both monomeric and polymeric compounds containing carbon, hydrogen, and oxygen atoms, and optionally nitrogen, sulfur, and halogens. Oxygen or nitrogen atoms, or both, are generally present in ether, ester, urethane, amide, and urea groups. The ethylenically unsaturated compounds preferably have a molecular weight of less than about 4,000, and are preferably esters generated from the reaction of compounds containing aliphatic monohydroxy groups, aliphatic polyhydroxy groups, as well as unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and the like.

Illustrative examples of photopolymerization initiators, which can be combined with acrylic compounds to be used herein, include: benzyl, -methyl o-benzoate, benzoin, ethyl benzoin ether, isopropyl benzoin ether, isobutyl benzoin ether, etc. ., benzylphenone / tertiary amine, acetophenones such as 2,2-diethoxyacete phenone, benzyl methyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropin-1-one, l- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-l-one, 2-benzyl-2-N, N-dimethylamino-1- (4-morpholinophenyl) -l-butanone, 2,4,6-oxide trimethylbenzoyldiphenyl-phosphine, 2-methyl-l-4 (methylthio), phenyl-2-morpholino-l-propinone, etc. These compounds can typically be used individually or in combination.

Illustrative examples of cationically polymerizable materials, and suitable for use herein, include materials that contain epoxy and vinyl ether functional groups. These systems are photoinitiated by onium salt initiators such as the triarylsulfonium salts, and the diaryliodonium salts.

Preferred polymers for forming the series of cubic corner e-elements in the retroreflective incorporations of the invention, include poly (carbonate), polymethylmethacrylate, poly (ethylene terephthalate), aliphatic polyurethanes and linked acrylates such as multifunctional acrylates or epoxies, as well as as acrylated urethanes joined with mono and multifunctional monomers. These polymers are preferred by one or more of the following reasons: thermal stability, environmental stability, clarity, excellent release from the machining or mold, and ability to receive a reflective cover.

Many of the aforementioned polymers for use in forming the microstructured surface do not form suitable bonds directly to highly plasticized PVC or ethylene copolymers such as EAA. In addition, these microstructured surfaces can be subject to degradation due to the migration and deposition of monomeric plasticizers from the plasticized PVC material by direct contact or as a vapor. One of the advantages of the present invention, is that the sealing layer can function as a barrier to the migration of the monomeric plasticizer from fibrous materials that have PVC covers -plasticized to retroreflective elements. Another advantage is that the sealing layer can allow the incorporation of fibrous membranes and matrix layers that are compatible or incompatible with the microstructured member.

The sealing layer is fused to the microstructured member next to the main layer, the microstructured surface or both. Typically, in the case of retroreflective incorporation, the seal layer is fused to the microstructured member in a network of interconnecting tie lines to form a series of seal cells containing a plurality of cube corner elements. As discussed in the U.S. Patent. No. 4,025,159 (McGrath) such a network of joints, as well as the main part of the sealing layer, provide retroreflective sealing cells of retroreflective e-lements in which an air contact surface is maintained on the surfaces of the joints. cubic corner elements. In some embodiments, the microstructured surface may be metallized, and the seal layer may be fused substantially to the metal surface in a continuous or discontinuous manner.

In addition, the sealing layer functions as a means of bonding the microstructured member to the support member by means of a fusion, for example, high-frequency welding and / or pattern heat welding.

An advantage of the invention is that the sealing layer can be first fused to the microstructured member in the desired pattern, taking into consideration the possible effects of the sealing pattern on the desired appearance of the member from the front surface, the retroreflective operation desired of the resulting article, etc. , and then subsequently fusing said sealing layer to the support member without substantially disturbing the fusion to the microstructured member. This allows to separate the optimization of both contact surfaces, as well as the optimization of the final product. For example, the sealing layer may be fused to the microstructured surface at a plurality of separate points or in an interconnection network of junctions, as disclosed in the US Pat. No. 4,025,159 (McGrath) to minimize breakage of the microstructured surface (unless the surface is metallized, the regions to which the sealing layer fuses, are optically deranged so much as to reduce the retroreflective effect of the metal sheet ), while the sealing layer is substantially and completely fused to the support member above its total surface to provide a strong cohesive interfacial junction. If it is desired, the sealing layer can be attached to the support member in a certain pattern, for example, point joints, or a network of joints, which turn out to be different from the pattern in which the sealing layer is fused to the microstructured surface.

The second polymer of the sealing layer is compacted with the first polymer of the microstructured member, that is, the two polymers can be fused together without undesirably degrading the microstructured characteristics of the microstructured member. Preferably, the sealing layer will provide a bond between the microstructure member and the support member, wherein the joint is characterized as having an average T-peel strength (measured in accordance with the test method described in FIGS. Examples that are presented below) of at least about 0.2 lbs "(0.9 Newtons), more preferably at least about 0.8 lb (3.6 Newtons), more preferably larger than about 2 lbs_ (9 Newtons).

Sometimes, the desired property in relation to the sealing layer, is that the second polymer acts as a barrier to the migration of monomeric plasticizers, for example, the migration of flexible structured material coated with PVC to which the article is attached. -retroreflexive. The barriers will retard or eliminate the migration of monomeric plasticizer to the microstructured surface, preserving the desired performance of the resulting article.

Illustrative examples of polymers suitable for use in a sealing layer include: polyurethanes, -alkylene acrylate / alkyl copolymers such as the ethylene / methyl acrylate lime flake, ethylene / N-butyl acrylate copolymer, copolymer ethylene / ethyl acrylate, ethylene / vinyl acetate copolymers, poly-plasticized PVC, as well as the main polyurethane of the ethylene / acrylic acid copolymer. Combinations of such materials can be used if desired. Those skilled in the art will recognize that the term "polyurethane" characteristically includes polymers possessing urethane and / or urea linkages, wherein this meaning is as contemplated herein, and -includes polyether polyurethanes, polyester polyurethanes, and polycarbonate polyurethanes. An illustrative example of a suitable EAA material for use in the invention is that known under the trade designation PRIMACOR Brand 3440, from Dow Chemical Company, Midland MI, which is a copolymer of ethylene acid and acrylic acid, wherein this last is present in a percentage by weight of -about 9 percent as a percentage of the total weight of the ethylene and acrylic acid monomer; the copolymer has a melt index of about 10. Polymerically plastered PVC is considered as a distinctly different material compared to monomerically plasticized PVC, since polymeric plasticizers do not move from PVC. Polymerically plasticized PVC will remain flexible and will not cause deterioration in the optical performance of the retroreflective layer.

Suitable polyurethanes for use as the sealing layers include: polyether polyurethanes, polyester polyurethanes, polycarbonate polyurethanes (where all can be aliphatic or aromatic in nature), and combinations thereof. A suitable combination consists of from about 50 to about 99 weight percent of polyester-aliphatic polyurethane with about 1 to 50 weight percent of a pigmented aromatic polyether polyurethane. An example of a suitable combination is one comprising 60% by weight of the aliphatic polyester polyurethane known under the trade designation MORTHANE Brand PN03.214, from Morton International, Seabrook, New Hampshire, with 40 percent in - weight of a pigmented aromatic polyether polyurethane. The pigmented aromatic polyether polyurethane consists of 50 weight percent of aromatic polyether polyurethane known under the trade designation of TIN Brand No. 58810, available from BF Goodrich Co., Cleveland, Ohio, and 50-weight percent dioxide titanium, previously composed of suitable means, such as in a screw extruder-double, and subsequently pelletized. Another illustrative example of a suitable polyurethane can be prepared by forming, with a double screw, with from about 1 to about 50% by weight of titanium dioxide directly in an aliphatic polyurethane, such as MORTHANE Brand PN03.214.

A useful ethylene / vinyl acetate ("AEV") copolymer is that known under the trade designation of ULTRATHANE UE Brand 646-04 from Quantum Chemical Company, Cincinnati, Ohio. Those skilled in the art will be able to determine, via T-peel tests, that ethylene copolymers, with a high comonomer content and with indexes - melting highs, are more easily fused. However, very high rates of fusion and / or a high content of Comonomer, it is apparent that the fusion force decreases.

In some articles within the invention, a multi-layer sealing layer can be used. An illustrative example of a multilayer version, is a layer of ethylene / vinyl acetate copolymer ("AEV") coated on a layer of ethylene / acrylic acid copolymers ("AEA"), wherein the AEA layer is placed against the support member, and the AEV layer has about 15 to about 50 per cent in mol vinyl acetate ("AV"), more preferably -about 30 to about 50 er cent in mol of AV. One layer can be selected to achieve the barrier properties in relation to the plasticizer and / or for adhesion to the strengthening member, while the other layer will serve to achieve adhesion to the microstructured surface.

The support member is a fibrous membrane consisting of a plurality of multifilament strands comprising a third polymer and having first and second sides, wherein the first side of the membrane is fused to the second surface of the sealing layer. . The fibrous membrane, in the support member, consists of a plurality of multifilament strands that are substantially unsaturated with encapsulating resin. Each strand consists of one. -Larity of filaments that can be interlaced or rolled together or not as much as desired. The filaments in a strand may be of substantially equal cross section diameter or of varying diameter as desired. The various strands, in a given support member, can be substantially uniform or different in diameter, number of filaments, length, composition of the filaments, etc. as much as desired.

The strands preferably consist of at least seven strands, more preferably 15 or more strands, and still more preferably about 30 or more filaments. At least some of the filaments within a strand, is free to move with respect to the other, is -that is, the filaments are not placed so tight, or joined together, or the interstices within the strand are not -saturated with resin (for example, of the sealing layer or the matrix layer), in order to prevent independent movement. As a result, the strand is more flexible, imparting greater flexibility to the resulting article of which it is a part. During the fusing of the sealing layer to the support member, the strands are not -saturated by material of the sealing layer, if the sealing layer directly contacts the fibrous membrane, or if the matrix layer is fixed. completely in there, thus conserving more flexibility according to the invention.

Figure 2 illustrates a cross section of a strand 100 consisting of a plurality of strands 102 in a support member 104 to which the sealing layer 106 has been fused. In addition to the strand 100, the support member 104 further comprises a matrix layer 108. According to the invention, the surrounding polymeric materials are bonded to the strand but do not penetrate the inner portions thereof, so that at least some of the individual filaments remain free to move - independently of someone else.

Illustrative examples of fibrous webs suitable for use in or as support members herein include welded, interlaced or non-interlaced structures, as well as loose fiber membranes, where all of these may be composed of one or more polyamide, polyester fibers, and cellulose Suitable support members have a base weight range (uncoated) of about 0.5 to about 20 ounces / square yard (about 17 to about 680 grams / metric square (gmc)), depending on flexibility desired - for the resulting article.

The fibrous membrane and / or the matrix layer, if present, may consist of polymeric materials that are compatible with the first polymer of the microstructured member, ie, polymeric materials that can not be fired thereon, if you want The fibrous membrane may be such that it is fused to the sealing layer and / or the matrix layer. However, characteristically, the fibrous membrane will be weakly fused, or substantially not fused thereto, allowing the filaments to move more freely. With the fibrous membrane encapsulated between the sealing layer and the matrix layer, as shown in Figures 2-4, and with a strong fusion between the sealing layer and the matrix layer, the integrity is maintained. structural of the shaped article. The fibrous membrane can impart great strength to the break, high tensile strength, etc. to the article conformed according to the -invention and without being strongly linked to the surrounding components of the article.

PVC is typically used in tarpaulin tarpaulins, spiral signs, and analogs, and provides good flexibility, resistance to abrasion, ultraviolet stability, and cold temperature performance. But PVC is also, characteristically, highly plasticized with monomeric plasticizers to achieve good flexibility, typically up to 30 to 40 weight percent of monomeric plasticizers. As discussed in the U.S. Patent. No. 5,069,964 (Tolliver), such a plasticizer can degrade the retroreflective performance of retroreflective articles of the cubic corner type if the plasticizer migrates or penetrates through the article. An advantage of the present invention is that the sealing layer or matrix layer of the support member can be selected to be a barrier against monomeric plasticizers if desired.

An alternate useful polymeric material for the tarpaulins of the trucks, signage in the form of a spire and the analogous ones, is the copolymer of ethylene / α-crylic acid. Like the PVC polymer, the AEA is flexible, durable, and resistant to abrasion. However, AEA films maintain their flexibility without the need to use -plasticizers. Other flexible ethylene copolymers, e.g., AEV or the ethylene / n-butyl acrylate copolymer, can also be used to coat an exterior surface of the structure.

As briefly summarized above, the method of the invention comprises: (a) a microstructured member consisting of (1) a main layer and (2) a microstructured layer comprising a series of microstructured elements, wherein at least one of the microstructured elements, as well as the main-layer portion close to said microstructured layer, it consists of a first polymer; Y (b) a sealing layer having a first and second surfaces and consisting of a second polymer, fusing at least a portion of the first surface of the sealing layer to the first polymer portion of the microstructured member; Y (c) a support member consisting of a fibrous membrane comprising a plurality of multifilament strands and consisting of a third polymer, and optionally a strand encapsulating member and having first and second sides; and (d) joining the first side of the membrane to the second surface of the sealing layer; to produce a flexible microstructured article with a support member.

As shown in Figure 8a, in some embodiments, the seal layer 204 will be bonded to the microstructured surface 202 of the microstructured member 200, ie, the microstructured surface 202 comprises the first polymer to which the second polymer of the layer seal 204 will be joined. As shown in Figure 8b, in some embodiments, the seal layer 210 will be attached to the main layer 206 of the microstructured member 207, being forced to come into contact, furthermore, between the microstructured elements 208 of the microstructured surface. In this case, the portion of the main layer 206 closest to the microstructure elements comprises the first polymer to which the second polymer of the seal layer 210 will be uni. do.

According to the invention, the sealing layer may be first fused to the microstructured member in a desired pattern, and subsequently fused to the support member in a different pattern and without substantially disturbing the fusion to the microstructured member (as shown in the Figure). 3). In some embodiments, the microstructured member will be fused to the seal layer, and the seal layer fused to the support member in a simultaneous manner. In other embodiments, the sealing layer will be first fused to the support member and then fused to the microstructured member (as shown in Figure 4).

Referring to Figure 3, the microstructured member 110 with a microstructured surface 112 (eg, polycarbonate) to which the sealing layer 114 (eg, urethane) has been fused into a plurality of merged points 116, it will be fused to support member 118 which consists of a fibrous membrane 120 and a matrix layer 122 (eg, urethane).

Referring to Figure 4, the microstructured member 130 with a microstructured surface 132 (e.g. polycarbonate) which has been metallized with a reflective layer 133 (e.g., an aluminum vapor layer), is fused to the sealing 134 (for example AEA) which has been fused to support member 136 consisting of a fibrous membrane 138 and a matrix layer 140 (eg, urethane).

In some characteristic embodiments, the microstructures have a height or depth of about 3.5 thousandths of an inch (85 microns), the sealing layer has a thickness of about 2.5 thousandths of an inch (62 microns), the strands of the membrane fibrous have a thickness of about 5 to 7 thousandths of an inch (125 to 175 microns) or a little more or less, and the matrix layer a-thickness of about 4 thousandths of an inch (100 microns). However, it will be understood that components with other dimensions than those mentioned above may be used according to the invention. Characteristically, it is preferred that the sealing layer be at least 2/3 of the thickness relative to the depth of the microstructures on the microstructured surface. If the threads are also -biggest, the resulting article will tend to be less flexible; If these strands are also thin, the article will tend to have a lower breaking strength. If the matrix layer is also thin, the fibrous membrane may not be sufficiently secured in the resulting article. If any of the components are also thin, the resulting article may not exhibit the desired flexibility.

The fusion techniques that may be used here include high frequency welding (eg, radio frequency welding and ultrasonic welding), thermal application, thermal extrusion, heat lamination, and the like.

For example, a suitable retroreflective microstructured surface having a plurality of polymeric microstructures which are normally incompatible for direct thermal coupling to non-compatible polymers, such as monomerically plasticized PVC or AEA, is selected. A composite of a sealing layer / support member is selected, which has an integral seal layer overlapped on one side thereof and in some cases a non-compatible polymeric layer placed between the fibrous material. At least a portion of the microstructured surface, as well as a portion of one side of the sealing layer, are brought into contact together and subjected to a high frequency energy, such as radiofrequency; in more cases, under pressure, or passing a current of heat. The frequency of the energy, the intensity of the field, the location (part-of above or part of below), the time, and the interval, are variable by an operator and are selected in relation to -their compatibility depending on the polymeric components . The choice depends on such factors, as well as on the factors of the individual polymer dielectric loss, the dielectric constants, the melting temperatures and the thickness of the layer. Radiofrequency energy is distributed through antennas mounted within appropriate plates that are pressed onto appropriate surfaces of the shaped article by applying an appropriate amount of pressure, as well as an appropriate duration of high frequency power. A general description of radiofrequency welding is given in Modern Plastics Encyclopedia, 1992, p. 350-352, (McGraw Hill).

In thermal welding of a microstructured member and a composite of a sealing layer / support member, the two materials are passed between a gripped roller and between a thermal roller embossed, applying an adequate pressure to the components by On top of an embossed pattern with a raised groove which remains on the surface of the embossed roller. The opposing force gripping roller is preferably a roller with a smooth surface based on a hard rubber, for example a roller with 85 Shore A durometer. The embossed roller is shaped to exert a pressure on the material to be welded only in the point of the furrows-raised. Both the embossed roller and the hard durometer roller are heated to suitable temperatures depending on the composition of the polymers used. The embossed pattern can be of various suitable patterns, such as a same chain pattern that is described later.

In an alternate method, a polymer for the compatible sealing layer is coated, preferably by extrusion coating, on a support member, allowing it to cool; likewise, a portion of the sealing layer is brought into contact with the structured surface (metallized or unmetalated) of the microstructured member, and the structure of the resulting composite is subjected to conditions (preferably - high frequency welding or thermal rolls) as explained above) sufficiently capable of fusing the composite of the sealing layer / support member to the microstructured surface in a plurality of locations.

Ultrasonic welding can be used to achieve fusion in accordance with the invention. In ultrasonic welding, high-frequency mechanical vibrations are transmitted through one of the coupling parts of the machine to the joint of the contact surface. A combination of applied force and surface and intermolecular friction at the contact surface joint raises the temperature to the melting point of the material. The force is maintained after the vibrations stop, producing the joint or welding. See Modern Plastics Encyclopedia (1992), pp 353-356.

The invention also contemplates microstructured surfaces that are specularly coated with covers of some metal or other suitable reflective covers, as a means to modify the optical operation of the member -microstructured. The invention anticipates the need to shape the metallized covers when RF welding is used, and to induce RF welding for those regions that are free of any metallization. It is known that a portion may consist of all the projection surfaces or less of said surfaces.

Figure 5 illustrates an embodiment of the retrospective article 50 of the invention, which consists of a retroreflective layer 52 and a support member coated with a polymer 53 with a sealing layer 54 on this member and consisting of a layer of PVC 55 and a fibrous membrane 57, which has been fused using radiofrequency welding energy through plates 56 creating RF weld 58 between the retroreflective layer 52 and the sealing layer 54.

Figure 6 illustrates a thermal method for constructing a retroreflective article of the invention 60 which consists of a retroreflective layer 62 and a polymer-coated structure material 63 with a sealing layer 64 and comprising a layer of PVC 65 and a structure 67 passing between the embossed roller 66 and the rubber roller 70. The embossed roller 66 consists of a ready-made e-groove 68, whereby using heat and pressure -between the rolls 66 and 70, it forms a thermal weld 72 between the retroreflective layer 62 and the sealing layer 64 corresponding to the assembled raised groove 68.

Figure 7 illustrates a planar view of a portion of an embossed roller used to make a crawled chain shaped article of the invention. The embossed roll 188 has embossed relief elements 192 on its surface to create a thermal welding pattern in the articles of the invention, corresponding to the embossed pattern of the raised grooves 192. FIG. planar view of an embossed pattern with raised groove 192 on the surface of the embossed roll 188, showing the dimensions of -pattern A, B, and C. Preferably, the ranges of dimension A are around 4 a about 50 millimeters ("mm"); the ranges of dimension B are preferably around 4 to about 50 mm, and the ranges of dimension C are preferably around 0.4 to about 4 mm.

An advantage of the present invention is that the items thereof can be constructed to maintain an excellent degree of flexibility without any breakdown or mechanical failure. For example, the metal sheet can be wrapped around in a curved shape or other non-flat surfaces without experiencing any damage. In one test, this flexibility was measured by wrapping the microstructured article - around a cylindrical mandrel with a diameter of 3.2 mm (0.125 inches). The test was performed at 0 ° C with good results, that is, no break was observed.

The articles of the invention can be made in a highly flexible form for use on flexible substrates, for example, PVC sheets which reach their flexibility using the monomeric plasticizers, staying resistant to degradation, for example, of optical performance, to the exposure of monomeric plasticizers.

Dyes, UV absorbers, light stabilizers, antioxidants with a free radical, process aids such as antiblock agents, release agents, lubricants, and other additives, can be added to the microstructured member as well as want. The particular dye selected (e.g. dyes and optionally fluorescent dyes) will, of course, depend on the desired color. The dyes are typically added in a weight percent of about 0.01 to 1.

UV absorbers are typically added in a weight percent of about 0.5 to 2. Illustrative examples of UV absorbers include benzotriazole derivatives such as those known under the trade designations TINUVIN Brand 327, 328, 900, 1130, and TINUVIN-P Brand, available by Ciba-Geigy Corporation, Ardsley, New York; benzophenone chemical derivatives such as those known under the trade designations UVINUL-M40, 408, D-50, available from BASF Corporation, Clifton, New Jersey; SYNTASE Brand 230, 800, and 1200 available from Neville-Synthese Organics, Inc., Pittsburgh, Pennsylvania; or chemical derivatives of diphenylacrylate such as UVINUL-N35 and 539, also available from BASF Corporation of Clifton, New Jersey. Light stabilizers that can be used include hindered amines which are typically used in about one percent by weight of 0. 5 to 2. Illustrative examples of hindered amine light stabilizers include those known under the trade designations TINUVIN-144, 292, 622, 770, and CHIMASSORB-944, all available from Ciba-Geigy Corp., Ardsley, New York. Antioxidants with a free radical can be used, characteristically, in a percent by weight of about 0.01 to 0.5. Illustrative examples with respect to suitable antioxidants include hindered phenolic resins such as those known under the trade designations IRGAN0X-1010, 1076, 1035, and MD-1024, and IRGAFOS-168, all available from Ciba-Geigy Corp., Ardsley, NY. Also, small amounts of other processing aids, typically not more than one percent by weight of the polymer resins, can be added in order to improve the processability of the resins. Useful processing aids include fatty acid esters, or fatty acid amides available from Glyco Inc., Norwalk, Connecticut, as well-such as metal stearates available from Henkel Corp., Hoboken, New Jersey, or WAX E available from Hoechst. Celanese Corpora- tion, Somerville, New Jersey.

Examples The features and advantages of this invention are further explained in the following illustrative examples. All the parts and percentages described here are - by weight, unless otherwise specified; "gmc" means grams per square meter.

Micro-structured Member The molten polycarbonate resin (known under the trade designation MAKOLON Brand 2407, supplied by Mobay Corporation (now Bayer), Pittsburgh, Pennsylvania) was cast on a microstructured nickel machining equipped with cube-corner voids and having a depth of -about 89 micrometers (3.5 thousandths of an inch). The holes were arranged as paired pairs of elements-cubic corner with the optical axis inclined or tilted 8.15 degrees of the primary groove, as generally described in US Pat. No. 4,588,258 (Hoopman). The nickel machining thickness was 508 micrometers (20 mils), and the machining was heated to 215.6 ° C (420 ° F). The molten polycarbonate at a temperature of 288 ° C (550 ° F) was cast on machining at a pressure of -7 7 approximately 1.03 x 10 to 1.38 x 10 pascals (1500 to 2000 pounds / square inch) per 0.7 seconds to double the microcubes. Coincident with the filling of the cubic holes, additional polycarbonate was deposited in a continuous ground layer above the machining with a thickness of approximately 104 micrometers (4 thousandths of an inch).

A pre-stretched, pre-stretched, 3-inch thick aliphatic polyester polyurethane main layer, MORTHANE PN03.214, available from Morton International, Seabrook, New Hampshire, was then laminated onto the top surface of the Polycarbonate earth continued when the surface temperature was approximately 191 ° C (375 ° F). Laminated polycarbonate and polyurethane microstructured member, combined, were then cooled with air at room temperature for 18 seconds at a temperature of about 70 ° C to 85 ° C (160 ° F to 190 ° F), allowing the materials solidify. The laminate was then removed from machining.

Intensity of the lamination The intensity of the fusion between the microstructured member and the sealing layer can be measured using a T-peel test. The T-peel test used here is based on the test of the American Society for Testing and Materials, number D 1876-93, except for the changes noted here. Samples were cut into strips about 25 mm (1 inch) wide with thermal or RF bonding parallel to the length of the strip. The index of separation of the embouchure was 305 mm / min (12 inches / min). The maximum load forces, as well as the (average) debarking forces are reported, at the moment in which the front of the descortezamiento moves around 20 mm along the union.

Example 1 A fibrous open-weave polyester material, consisting of 1000 denier fibers, 3.5 ends per cm (9 ends per inch) in each direction, and with a basis weight of about 95 gmc (2.8 ounces per square yard) of Milliken Co. , Spartanburg, South Carolina, was used as the fibro-sa membrane of the support member. This interlaced fibrous material has openings which allow the flow of molten thermoplastic resins. On a main surface of the fibrous material was heat-laminated an ABA layer not compatible and coated, as well as previously stretched (153 micrometers thick (6 mils)) to form a matrix layer. The AEA was obtained by Dow Chemical Co., in pellet form, under the commercial designation PRIMACOR 3440. On-the second major surface of the fibrous material was heat-laminated, a layer of polyurethane with a thickness of 63.5 micrometers (2.5 mils. inch) coated, as well as previously stretched in conjunction with a sealing layer. The polyurethane was obtained in pellet form from Thermedics Co., of Woburn, Massachusetts, and consists of an aliphatic polyester polyurethane pigmented by titanium dioxide with a hardness of 93 strut A.

Five of these sealing layer / support member compounds were produced to bond to the aforementioned retroreflective metal sheet, then submitted to the T-peel test, with the pigmented polyurethane layer to be fused. to the microstructured surface of separate pieces of the retroreflective sheet.

Example 2 Two sealing layer / support member compounds were made as in Example 1, except that the polyurethane layer had a thickness of 127 micrometers (5 mils).

Example 3 Four sealing layer / support member compounds to be attached to the retroreflective sheet and subsequently subjected to the T-peel test were made as in Example 1, except that the polyurethane was a 60 weight percent combination. of aliphatic polyester polyurethane known under the trade designation MORTHANE PN03.214, available in pellet form by Morton International, Seabrook NH, with 40 weight percent of a pigmented aromatic polyether polyurethane (pigmented aromatic polyether polyurethane consists of 50 percent by weight of titanium dioxide and 50 weight percent of polyether aromatic polyurethane known under the trade designation TIN 58810 from BF Goodrich Co., Cleveland, OH, which has been previously formed into a twin screw extruder, as well as peleti-zado).

Example 4 Four sealing layer / support member compounds to be attached to the retroreflective sheet and then subjected to the T-peel test, were processed as in Example 3, except that the polyurethane layer had a thickness of 114 micrometers (4.5 thousandths of an inch).

Examples 5A-5D Four sealing layer / support member compounds were made as in Example 1, except that the polyurethane layer was replaced by a stretched double layer film in which one layer comprises AEA and the one as layer comprises AEV, wherein the percentage of vinyl acetate in the AEV layer was as indicated in Table 1. The AEA side of the double layer film was laminated to the second major surface of the composite. The thickness of the AEA layer in each of the articles was 50 micrometers (2 mils), while the thickness of the AEV layer was 12 micrometers (0.5 mils-inch) for the articles of the Examples 5A and 5B, as well as about 25 micrometers (1 mil) for the articles of Examples 5C and 5D.

Example 6 The articles of this example were identical to those of Example 4, except that both major surfaces of the composite have the polyurethane coating. Three of these samples were produced to join and to undergo the T-pee test] (Detachment T) Example 7 In these constructions, a fibrous material woven in nylon and coated with tightly woven polymer and manufactured by Burlington Insustries, known under the trade designation ULTREX, was employed. This structure, sealed with polymer, has a basis weight (as cover) of about 4.5 ounces per square yard (about 150 gmc) and has extremes of 60 x 120 per inch (152 x 304 limbs per cm), which of nylon fibers with around 200 denier. The matrix layer on a main surface of the fibrous membrane was subjected to a vapor-water stream passing through the polymer-coated fibrous material, not allowing the passage of liquid water through said material.

To the uncoated side, the polyurethane-discussed in Example 3, to a thickness of 114 micrometers was heat laminated (4.5 mils) to form a sealing layer. Three of these constructions were produced to join and - to undergo the T-peel test.

Example 8 In these constructions, a nylon woven fibrous material, with about 152 limbs per cm (60 limbs per inch) in both directions, and with a basis weight of about 107 gmc (about 3.2 ounces per square yard), It was used as the support member. To a main surface, the polyurethane of Example 3 was heat laminated to a thickness of 114 micrometers (4.5 mils) to form a sealing layer. Two of these models were elaborated.

Example 9 The sealing layer was made as follows. A 60% combination of aliphatic polyester polyurethane (MORTHANE Brand PN03-214) and 40% aromatic polyester polyurethane was fed into an extruder and stretched on a PET carrier film. This aromatic polyurethane consists of a 50% blend of AERIAL polyester polyurethane Brand 58110 available from B. F. Goodrich, Cleveland, -Ohio, and 50% titanium dioxide. The mixture was previously formed into a twin screw extruder, as well as pelletized. The extruded sealing layer had a thickness of 64 micrometers (0.0025 inches). The PET carrier film had a thickness of 51 micrometers (0.002 inches).

The microstructured member, as well as the bundle layer, were fed into a constriction created between a steel embossed roller and a rubber roller - with a duralimeter 75 of strut A. The microstructured member was brought into contact with the roller embossed with the exposed cubic corner side. The PET film of the sealing layer was brought into contact with the rubber roller, the sealing layer being exposed. The embossed steel roller was heated to 243 ° C (470 ° F). The rollers-turned at a speed of 1.52 meters / minute (5 feet / min.), And the force on the narrowing was about 86 N / cm (50 lb / inch) to create joints between the cubic corners and the sealing member exposed. A retroreflective sheet is obtained as the resulting product.

A support member was made as described in Example 1, except that the non-compatible AEA layer was not used. The polyurethane film, as well as the polyester fibrous material, were fed in a constriction with the polyurethane film in contact with the hot drum and the polyester in contact with the rubber roll. The lamination of the two films occurred at a temperature of 104 to 116 ° C (220 to 240 ° F), at a limit speed of 6 to 12 meters / minute (20 to 40 feet / minute), and at a pressure in the narrowing from 12 to 26 N / cm (7 to 15 pounds / inch). The resulting support member has the cut partially fixed in the polyurethane film.

The retroreflective sheet was laminated to the support member to produce an article of the present invention. The support member was placed in contact with the hot drum and with the exposed side exposed. The retroreflective sheet was placed in contact with the embossed roll, with the sealing layer exposed. The lamination of the two films occurred at a temperature of 104 to 116 ° C (220 to 240 ° F), at a limit speed of 3 to 12 meters / minute (10 to 40 feet / minute), and to a pressure in the narrowing from 12 to 24 N / cm (7 to 14 pounds / inch).

Comparative Example A A structure coated with polymer known under the trade designation DURASKIN, model number B156035, available from Verseidag-Indutex GmgH, Krefeld, Germany, was used as the support member. This coated structure has a woven polyester carving of 610 grams per square meter (18 ounces / square yard), coated on both sides with a highly plasticized monomeric polyvinyl chloride as the matrix layer. Four of these coated structures were joined and tested by the T-peel test.

Comparative Example B In this example, a polymer-coated structure was made as in Example 1, except that the polyurethane layer was replaced with a stretched AEA layer identical to that coated on the first major surface. One of this type was developed.

Comparative Example C A retroreflective article commercially available by Reflexite Corporation, with the alleged business designation 393-2457-372, was employed. This was a cubic corner layer with a PVC content, adhered (fused) to a carving coated with PVC.

Mounting Some of the sealing layer / support member compounds of Examples 1-8 (as indicated in Table 1), were laminated together with separate pieces of the retroreflective sheet with the compatibilizing layer in front of the cubic corners and thermally welded in a stroke pattern of about 4 mm wide by 180 mm in length. The samples were thermally welded in a heated plate press in which an aluminum plate, with a high-riser (3 mm high by 2.8 mm wide by 180 mm long), was fixed to the upper plate. The retroreflective layer, on each side, was protected by a polyester terephthalate film (25 micrometers thick) following the sealing groove. The support member was also protected by a polyester terephthalate film (51 micrometer thick) following the lower plate. The plates were preheated to 160 ° C (320 ° F), the samples placed in the press, and the press was closed with a force of 35,000 Newtons (8000 pounds) pressing for 3 to 5 seconds before opening and removing the sample. The protective layers of polyester terephthalate were then removed from the samples. Table 1 indicates which samples were joined - thermally. Alternatively, the constriction between a steel embossed roller and a rubber roller can be used to effect thermal coupling. The steel roller is typically heated, and has a crawler pattern as shown in Figure 8.

All samples of Examples 1-8 and Examples A, B, and C were also laminated together with separate pieces of laminate, as described in Example 1, with the sealing layer in front of the cubic corners . Samples were welded using a bar-shaped die with 3.2 mm (0.125 inches) in width and about 2.54 cm (1 inch) in length. Approximately a power of 1 to 2 kW of radiofrequency was used at a frequency of 27.12 Mhz. Currently the power of the generator indicated in Table 1, is currently expressed as a percentage of 4 kilowatts. For example, the first entry in the table is 42 percent of 4 kilowatts, or 1.7 kilowatts. The welding equipment was set up in the conditions indicated in Table 1. The pressure exerted during the welding was around 2 2000 psi (about 1.4 Newton! Cm) and the interval between the -element elements of the machine. welding was 0.5 mm (2 mils), or about 0.25 mm (1 mil) (identified as "G" for large and "C" for small, respectively). The RF welding equipment that was used was obtained by Thermatron, Electronics Division of Wilcox and Gibbs, New York, New York.

The retroreflective shaped articles were then tested to measure their binding intensity, according to the T-peel test previously described; the results are given in Table 1. In Table 1 it can be seen that the maximum load and average force of T-peel was generally higher for the inventive articles. Where T-peel was highest for a comparative article, the failure was cohesive (within the coating of the polymer-coated structure), which is undesirable.

TABLE 1 Failure mode: RF detachment from the RC detachment structure from the cohesive CO cubes within the compatibilizing layer TABLE 1 (continued) Failure mode: RF detachment from the RC detachment structure from the cohesive CO cubes within the compatlbilizantß layer Various modifications and alterations of this invention will become apparent to those skilled in the art, without departing from the scope and spirit of this invention.

It is noted that in relation to this date, the best method known by the applicant to bring to practice the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, it is -claimed as property contained in the following.

Claims (15)

1. A microstructured article consisting of (a) a microstructured member comprising a -main layer and a microstructured layer consisting of a series of microstructured elements, characterized in that at least one of the microstructured elements, as well as the portion of the layer closest to the microstructured layer, consist of a first polymer; Y (b) a sealing layer having first and second surfaces and consisting of a second polymer; at least a portion of the first surface of the sealing layer is fused to the microstructured member, characterized in that the article further comprises (c) a support member, which consists of a fibrous membrane comprising a plurality of multifilament strands consisting of a third polymer and having first and second sides; the first side of the membrane is fused to the second surface of the sealing layer.

2. The article according to claim 1, characterized in that at least a part of the bundle member is fused to the main layer, the microstructured layer, or both.

3. The article according to any of claims 1 or 2, characterized in that the microstructured layer consists of a plurality of corner elements -cubic, and the article has a coefficient of retroreflectivity greater than about 250 candelas / lux / square meter.

4. The article according to any of claims 1-3, characterized in that the fibrous membrane is selected from the group consisting of woven membranes, non-woven membranes, bonded membranes, and loose strand mats.

5. The article according to any of claims 1-4, characterized in that at least some of the filaments within a strand are free to move with respect to one another.

6. The article according to any of claims 1-5, characterized in that the main portions of the strands are not impregnated with polymer encapsulant.

7. The article according to any of claims 1-6, characterized in that the fibrous membrane is directly contacted with the sealing layer.

8. The article according to any of claims 1-7, characterized in that the support member further comprises a matrix layer.

9. The article according to any of claims 1 - 8, characterized in that the first polymer has a higher melting point compared to the melting point of the second polymer.

10. The article according to any of claims 1-9, characterized in that the sealing layer consists of a polymer having a dielectric loss factor greater than about 0.06.

11. The article according to any of claims 1-10, characterized in that the sealing layer encapsulates the portions of the microstructured member in sealed cells.

12. The article according to any of claims 1-11, characterized in that the first polymer, the second polymer, as well as the fibrous membrane, consist of a different polymer.

13. The article according to any of claims 1-12, characterized in that the article is flexible enough to form a mandrel of -3.2 mm (0.125 inches) in diameter at 0 ° C without presenting visible breakage.

14. The article according to any of claims 1 - 13, characterized in that the article is -one of the following: a portion of a signal in the path, a spiral-shaped signal, a garment, -an accessory of a bag, a protective cover, a sheet, a tarpaulin, a warning tape, a decorative tarpaulin, a structural tarpaulin, or pieces attached to such-items.

15. A method for making a microstructured article with support member according to any of claims 1-14, characterized in that the method comprises: (a) a microstructured member consisting of a main layer and a microstructured layer consisting of a series of microstructured elements in which at least one of the microstructured elements, as well as the portion of the main layer closest to the microstructured layer, they consist of a first polymer; Y (b) a sealing layer having first and second surfaces and consisting of a second polymer; and fusing at least a portion of the first surface of the sealing layer to the microstructured member, characterized in that the method further comprises: (c) a support member which comprises a fibrous membrane consisting of a plurality of multifilament strands comprising a third polymer and having first and second sides; Y (d) fusing the first side of the membrane to the second surface of the sealing layer. The microstructured articles of the invention consist, in order of: a) a microstructured member; b) a sealing layer fused to the microstructured member; c) a support member. The support member is a fibrous membrane that consists of a plurality of multifilament strands and is fused to the second surface of the sealing layer.