HK1063302B - Magnetic substrates, composition and method for making the same - Google Patents

Description

Magnetic substrates, compositions and methods of manufacture

Cross relation with related applications

This application claims priority in accordance with the following U.S. provisional application patents: provisional patent application No. 60/253,191 (filed on 26/11/2000), the entire contents of which are incorporated herein by reference.

Field of the invention

The present invention relates to a method of making a printable magnetic assembly that is capable of self-attachment to a magnetically attractable surface, a magnetic composition for making the magnetic assembly, and articles made therefrom.

Background of the invention

Flexible permanent magnet materials are often made in sheet or coil form and have been on the market for many years. These materials are typically manufactured by mixing powdered ferrite material with a suitable polymer binder or plastic binder into a homogeneous mixture. The polymeric material is typically elastomeric and thus its manufacturing process is typically accomplished by extrusion and rolling into thin sheets. The above mixture, after conversion to tape or sheet form, provides a generally somewhat flexible, long-term stable product that can be readily processed by cutting and/or punching into the various shapes of elements that we desire.

The magnetic material is permanently magnetized so that the resulting component can act as a permanent magnet whose magnetic field must have sufficient field strength to adhere to a magnetically attractable surface, such as the surface of an iron or steel sheet, even with a paper or cardboard sheet therebetween. Many magnetic materials and sheet materials made therefrom are generally dark in nature, and thus the magnets are typically glued to a printable substrate (e.g., paper and plastic). So that decorative patterns and/or other information can be printed on the paper or plastic. One common use of such materials is to have decorative patterns and/or promotional messages on the outer surface of the thin, flat magnet, including direct mail, newspaper-inserted and other forms of advertising, case tops, merchant coupons, business cards, calendars, greeting cards, postcards, and other messages.

These magnet elements can be placed on a surface that can be magnetically attracted (for example a refrigerator, a file cabinet, or other surface) for direct use as a notification, and are also often used to hold paper such as notes, prescriptions, lists, artwork for children, memorandum tips, and the like.

In the usual production of these articles, there is an intervention of various manufacturers. For example, printing manufacturers produce printed matter in wide rolls or sheets. In the case of a web, the web is cut into individual sheets and shipped to a magnetic material manufacturer where the magnetic material and printed matter are glued together by using an adhesive layer. The printing manufacturer may also purchase or otherwise obtain magnets and use an adhesive layer to adhere the print to the magnet. Or the printed matter and the magnet are shipped to another manufacturer where they are glued together.

There remains a need in the art to simplify the production of these magnets.

Summary of The Invention

The present invention relates to a method for the integral production of a printable magnetic assembly, in which at least one magnetic layer is formed directly and can be joined to a printable substrate layer without the need for an adhesive layer. The adhesion between the magnetic layer and the printable substrate is sufficiently great that no adhesive is required. This method allows a magnetic layer to be formed and attached to a printable substrate in a single process. The formation and attachment of the magnetic layer is carried out at a temperature high enough to transform the magnetic layer into a pliable or plastic form.

The method of the present invention may further comprise a magnetization step, which may be performed while the magnetic layer is heated to an elevated temperature, or after the magnetic layer is cooled to ambient temperature.

The magnetic layer is formed from at least one magnetic material and at least one thermoplastic material, wherein the magnetic material is present in an amount of about 70-95% by weight and the thermoplastic material is present in an amount of about 5-30% by weight.

In one embodiment of the present invention, the magnetic material has the general formula M²⁺O6Fe₂O₃(M²⁺Fe₁₂O₁₉) In the formula, M represents a divalent metal, preferably barium, strontium, or lead. In some embodiments, the polymeric binder comprises at least one amorphous polypropylene.

The method of the present invention further comprises applying the magnetic layer directly to the printable substrate at elevated temperature while the magnetic layer is in a pliable or plastic state. The advantage of the method according to the invention is that no further adhesive layer is required.

The present invention provides in a first aspect a method of forming a magnetic assembly of the type consisting of at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, the method comprising the steps of:

a) providing a magnetic composition that is hot-melt at elevated temperatures, the hot-melt magnetic composition comprising 75-95 wt.% of at least one magnetic material and 5-25 wt.% of at least one thermoplastic binder;

b) forming the magnetic composition into the magnetic layer at an elevated temperature;

c) the hot melt magnetic composition is applied directly to a printable substrate layer when it is in a flexible state at elevated temperatures.

In a preferred embodiment of the invention, the method further comprises subjecting the magnetic assembly to a strong magnetic field sufficient to produce a permanent magnetic effect in the assembly when the magnetic composition is at an elevated temperature or when the magnetic composition is cooled to room temperature.

In a preferred example of the invention, the at least one magnetic material is present in a concentration sufficient to cause the magnetic assembly to self-adhere to a substrate comprising ferromagnetic material.

In a preferred embodiment of the invention, said applying step b) secures said magnetic layer to said printable substrate layer at the thickness and width of the final article, or said applying step b) secures said magnetic layer to said printable substrate layer at the thickness, width and length of the final article.

The invention also provides a method of forming a mat product comprising forming a plurality of sheet magnetic assemblies by the method of the first aspect of the invention, and laminating the sheet assemblies together to form a laminated mat.

In a preferred embodiment of the invention, the plurality of sheet assemblies are bonded together by means of an adhesive or shrink wrapping.

In a preferred embodiment of the invention, the coating temperature is between 90 and 205 ℃.

In a preferred embodiment of the present invention, the forming method includes a step selected from the group consisting of extrusion, roll coating, gravure coating, screen printing, and slot die coating.

In a preferred embodiment of the present invention, the magnetic material has the following general formula:

M²⁺O6Fe₂O₃

wherein M represents a divalent metal.

In a preferred embodiment of the invention, the divalent metal is barium, strontium, lead or a mixture thereof.

In a preferred embodiment of the present invention, the at least one thermoplastic binder comprises at least one component selected from the group consisting of natural rubber, block copolymers, polyolefins, polyesters, polyamides, nylons, polyurethanes, and copolymers or mixtures thereof.

In a preferred embodiment of the invention, the polyolefin is a polyalphaolefin.

In a preferred embodiment of the present invention, the at least one thermoplastic binder comprises at least one amorphous polypropylene, at least one interpolymer of ethylene and at least one alpha-olefin, at least one copolymer of ethylene and vinyl acetate, at least one copolymer of ethylene and an acrylate, at least one copolymer of ethylene and a methacrylate, at least one copolymer of ethylene and n-butyl acrylate, or a mixture thereof.

In a preferred embodiment of the invention, the at least one thermoplastic binder comprises a mixture of ethylene-vinyl acetate copolymers.

In a preferred embodiment of the present invention, the at least one magnetic layer has a thickness of 50 to 765 μm.

In a preferred embodiment of the invention, the magnetic composition is applied to the printable substrate in the form of at least one tape.

In a preferred embodiment of the present invention, the magnetic layer is further connected to a release liner.

In a preferred embodiment of the invention, the object is a magazine, book, food packaging bag, beverage packaging box, envelope or box.

In a preferred embodiment of the invention, the magnetic assembly further comprises a cover laminate on the printable substrate layer.

In a preferred embodiment of the invention, the cover laminate is perforated with approximately the same dimensions as the magnetic assembly.

In a preferred embodiment of the present invention, the magnetic layer is continuous with the printable substrate layer, or the magnetic layer is applied in a discontinuous pattern on the printable substrate layer.

In a preferred embodiment of the invention, the magnetic layer and the printable substrate layer have the same length and width.

In a preferred embodiment of the present invention, there is sufficient adhesion between the magnetic layer and the printable substrate layer without an additional adhesive layer between the magnetic layer and the printable substrate layer.

In a second aspect, the present invention provides an article capable of adhering to a magnetic surface, having at least one printable substrate layer and at least one magnetic layer, said magnetic layer comprising 75 to 95 wt% of at least one magnetic material and 5 to 25 wt% of at least one thermoplastic binder, said thermoplastic binder comprising at least one amorphous polypropylene.

In a preferred embodiment of the present invention, the article comprises:

a) a first magnetic layer comprising 5-25 wt% of at least one thermoplastic binder and 75-95 wt% of at least one magnetic material;

b) a second layer of printable material.

In a preferred embodiment of the invention, the article is in the form of a reminder slip, greeting card, postal card, coupon, label, business card, advertisement, calendar, receipt, schedule or promotional card.

In a preferred embodiment of the invention, the first layer has a thickness of 50 to 765 microns.

In a preferred embodiment of the present invention, the at least one adhesive composition comprises at least one component selected from the group consisting of natural rubber, block copolymers, polyolefins, polyesters, polyamides, nylons, polyurethanes, and copolymers or mixtures thereof.

In a preferred embodiment of the invention, the polyolefin is a polyalphaolefin.

In a preferred embodiment of the invention, the at least one binder is amorphous polypropylene or a copolymer thereof, an interpolymer of ethylene and at least one alpha-olefin, a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and n-butyl acrylate, a copolymer of ethylene and an acrylate, a copolymer of ethylene and a methacrylate, or a mixture thereof.

In a preferred embodiment of the present invention, the magnetic material is at least one compound having the following general formula: m²⁺O6Fe₂O₃Wherein M represents a divalent metal.

In a preferred embodiment of the invention, the divalent metal is barium, strontium, lead or a mixture thereof.

In a third aspect, the present invention provides a magnetic composition comprising:

a) 5-25% by weight of at least one polyalphaolefin binder, said polyalphaolefin being amorphous polypropylene or a copolymer or terpolymer; an interpolymer of ethylene and at least one alpha-olefin; or a mixture of these or a mixture of them,

b)75-95 wt% of at least one magnetic material.

34. The composition of claim 33, wherein the magnetic material has the formula:

M²⁺O6Fe₂O₃

wherein M represents a divalent metal.

In a preferred embodiment of the invention, the divalent metal is barium, strontium, lead or a mixture thereof.

In a fourth aspect, the present invention provides a method of forming a magnetic assembly of the type consisting of at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, said method comprising extruding at elevated temperature a magnetic composition comprising 70 to 95 wt% of at least one magnetic material and 5 to 30 wt% of at least one thermoplastic binder selected from the group consisting of natural rubber, block copolymers, polyolefins, and copolymers or mixtures thereof, onto a printable substrate layer.

In a preferred embodiment of the invention, the polyolefin is a polyalphaolefin.

In a preferred embodiment of the invention, the at least one thermoplastic binder is an ethylene-vinyl acetate copolymer.

In a fifth aspect, the present invention provides a method of forming a mat article comprising a plurality of magnetic sheet assemblies having at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, said method comprising the steps of:

a) providing a molten magnetic composition comprising 70-95 wt.% of at least one magnetic material and 5-30 wt.% of at least one thermoplastic binder;

b) applying the magnetic layer directly to a printable substrate layer while in a flexible state at an elevated temperature to form a magnetic assembly;

c) forming the magnetic assembly in b) into a plurality of magnetic sheet assemblies;

d) laminating the sheet assemblies together to form a stacked mat.

In a preferred example of the invention, the method further comprises bonding the sheet assemblies together.

In a sixth aspect, the present invention provides a method of forming a magnetic assembly of the type consisting of at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, the method comprising the steps of:

a) providing a molten magnetic composition comprising 70-95 wt.% of at least one magnetic material and 5-30 wt.% of at least one thermoplastic binder;

b) applying the magnetic layer directly to a printable substrate layer when the magnetic layer is in a flexible state at elevated temperatures

c) The magnetic layer is magnetized at a high temperature.

Brief Description of Drawings

FIG. 1 is a cross-sectional view of a magnetic assembly of the present invention

Figure 2 illustrates one embodiment of the present invention with the magnetic assembly on the printable substrate layer in small spaced apart regions.

Figure 3 illustrates one embodiment where the magnetic assembly and printable substrate layer are substantially equal in length and width.

Figure 4A is a perspective view of the magnetic marker assembly of the present invention provided on an object.

Figure 4B is another embodiment as shown in figure 4B with the magnetic assembly further having an upper cladding stack.

Figure 5 is an embodiment of the magnetic assembly of the present invention as a single sheet cut from a large sheet or web.

FIG. 6 is another embodiment as shown in FIG. 5, with magnetic layers located in spaced apart regions of a large sheet or web of printable substrate.

Figure 7 is a perspective view of an embodiment of the present invention, a stack of single magnetic assemblies.

Figure 8 illustrates one embodiment of a magnetic assembly of the present invention.

Figure 9 illustrates another embodiment of the magnetic assembly of the present invention.

Figure 10 illustrates another embodiment of a magnetic assembly of the present invention.

Figure 11 is a side view of an embodiment of a magnetic assembly of the present invention further including a release liner and an overlying layer stack.

Fig. 12 is a top view of the embodiment of fig. 11, with the upper cover stack further including holes.

Fig. 13 shows a specific embodiment of fig. 11 and 12 in the form of a single sheet.

Figure 14 is a side view of another embodiment of a magnetic assembly of the present invention.

Fig. 15 is a top view of the embodiment shown in fig. 14.

Detailed description of the preferred embodiments

The following description is merely exemplary in nature and the scope of the present invention is not limited to the descriptions.

Those skilled in the art will recognize various alternatives and modifications to the embodiments employed herein.

The present invention relates to a novel method of making a printable magnetic assembly, a magnetic composition and articles made therefrom.

The magnetic base material layer comprises a magnetic material, and the weight percentage of the magnetic base material layer is as follows: preferably in the range of about 75 to about 95, more preferably in the range of about 80 to about 92, and most preferably in the range of about 85 to about 90%; the magnetic base material layer also comprises a polymer adhesive, and the weight percentage of the polymer adhesive is as follows: a suitable range is about 5 to about 25, a preferred range is about 8 to about 20, and a most preferred range is about 10 to about 15%. The magnetic material is uniformly dispersed in the polymer binder.

As used herein, "magnetic" (in the context of substrates, articles, and the like) refers to any material that is permanently magnetic or readily permanently magnetized.

Magnetic materials particularly suitable for use in the present invention include those having the general formula (M)²⁺O6Fe₂O₃)M²⁺Fe₁₂O₁₉Wherein M represents barium and strontium.

Other magnetic materials suitable for use in the present invention include those having the formula RCO₅Where R is one or more rare earth metal elements, such as samarium or praseodymium, yttrium, lanthanum, cerium, etc.

The magnetic material of the present invention also includes other specific examples such as manganese bismuth, manganese aluminum, and the like.

The method of the present invention is not limited to any one particular magnetic material and the scope of the present invention is not limited thereto. Although the materials described above are particularly applicable in the method of the present invention, other materials that are readily permanently magnetized may also be used.

The magnetic composition preferably contains about 70 weight percent or more of the magnetic material in order to have sufficient attraction in practical applications. However, it is impractical to include more than 95% magnetic material from a production standpoint, and it is difficult to attach so much magnetic material in the adhesive material. Furthermore, the inclusion of 95% magnetic material also results in a rough surface, since the magnetic material is often provided in powder form.

The magnetic induction of the finished product is influenced by the following factors: the amount of magnetic material or magnetic powder in the mixture, the surface area, the thickness, the method of magnetization (e.g., whether the magnetic powder particles are oriented).

Thermoplastic materials, often referred to in the industry as thermoplastic adhesives. Suitable thermoplastic adhesives that may be used in the present invention include polymeric materials that are readily processed with magnetic materials on thermoplastic or hot melt processing equipment such as that described below. These thermoplastic materials include thermoplastic elastomers and thermoplastic nonelastomers or mixtures thereof.

The thermoplastic composition may be selected based on the following factors: the type of printable substrate used, and the adhesion that can be achieved between the thermoplastic composition and the printable substrate.

Thermoplastic elastomers suitable for use in the present invention include, but are not limited to, natural and synthetic rubbers and rubbery block copolymers such as butyl rubber, neoprene, ethylene-propylene copolymers (EPM), ethylene-propylene-diene polymers (EPDM), polyisobutylene, polybutadiene, polyisoprene, styrene-butadiene (SBR), styrene-butadiene-styrene (SBS), styrene-ethylene-butylene-styrene (SEBS), styrene-isoprene-styrene (SIS), styrene-isoprene (SI), styrene-ethylene/propylene (SEP), polyester elastomers, polyurethane elastomers, and the like, and mixtures thereof. Copolymers of the above are also included within the scope of the invention, where applicable. Thermoplastic elastomers that have been commercially produced include SBS, SEBS, or SIS copolymers, including block copolymers available under the trade names KRATON SG (SEBS or SEP) and KRATON D (SIS or SBS) from Kraton polymers; block copolymers available under the trade name vectores (SIS or SBS) from Dexco chemical company; the trade name FINADENE (SIS or SBS) block copolymer is manufactured by Atofina.

Non-elastomeric polymers include (but are not limited to): polyethylene, polypropylene, polybutylene and their copolymers and terpolymers, for example: ethylene-vinyl acetate copolymer (EVA), ethylene-n-butyl acrylate (EnBA), ethylene-methyl (meth) acrylate (including ethylene-methyl acrylate (EMA)), ethylene-ethyl (meth) acrylate (including ethylene-ethyl acrylate (EEA)), ethylene and at least one C₃-C₂₀And the like (to name only a few), and mixtures thereof. As long as it is applicableCopolymers of the above may also be used in the present invention.

Examples of polymers suitable for use herein can be found in U.S. patent No. US 6262174, which is incorporated herein by reference in its entirety. Polymers having high hot tack are particularly suitable for use in the present invention. Hot tack is a term of art known to those of ordinary skill.

Commercially available non-elastomeric polymers include, to name a few, the EnBA copolymers produced by the following companies: atofina (trade name LOTRYL), ExxonMobil (trade name ESCORENE), Du Pont de Nemours (trade name ELVALOY); also included are EMA copolymers (trade name OPTEMAO) from Exxon chemical; also included are EVA copolymers produced by the following companies: du Pont company (trade name ELVAXS), Equistar company (trade name LTLTRATHENE).

In some embodiments of the invention, the adhesive comprises at least one polyolefin or polyalphaolefin or copolymer or terpolymer thereof. Suitable polyolefins include (but are not limited to): amorphous (i.e., irregular) polyalphaolefins (APAO), such as amorphous propylene homopolymers, propylene/ethylene copolymers, propylene/butene copolymers, and propylene/ethylene/butene terpolymers; isotactic polyalpha-olefins; and linear or substantially linear interpolymers of ethylene and at least one alpha-olefin, such as ethylene and 1-octene, ethylene and 1-butene, ethylene and 1-hexene, ethylene and 1-pentene, ethylene and 1-heptene, and ethylene and 4-methyl-1-pentene, and the like. In some embodiments, it may be desirable to use small amounts of other polymers along with the polyalphaolefin, such as maleic anhydride grafted polymers, which have been used to improve wetting and adhesion. Other chemical grafting materials may also be used, but maleic anhydride is most used. Usually only a few percent (1-5%) of the graft is used and is preferably applied to copolymers of ethylene or propylene.

The terms "polyolefin" and "polyalphaolefin" are often used interchangeably and, in fact, are often used interchangeably to describe amorphous polypropylene (homopolymer, copolymer or terpolymer). For a detailed description of such materials, reference may be made to U.S. patents US 5482982, US 5478891 and US 5397843,4857594, each of which is incorporated herein by reference in its entirety.

The term "α" is used to indicate the position of a substituent or substituent group in an organic compound.

The terms "copolymer" and "interpolymer" herein refer to polymers having two or more different comonomers, e.g., copolymers, terpolymers, etc.

Amorphous polyolefins suitable for use in the present invention have been commercially produced including: commercial products available under the name REXTACS from Huntsman polymers including polypropylene homopolymers, propylene/ethylene copolymers and propylene-butene copolymers; commercial products manufactured by Hills company under the name of vetoplast APAO, including homopolymers and copolymers, also including propylene/ethylene/butene terpolymers; there are also products from Rexene and a commercial product known under the name EASTOFLEX from Eastman in Kingsport, TN.

Copolymers of polyolefins and at least one alpha-olefin include metallocene catalyzed polyolefins (interpolymers of ethylene and at least one alpha-olefin), such products having been commercially produced in: exxon (trade name EXACTS), DupontDow Elastomers (trade name ENGAGED), and Dow (trade name AFPINITY).

In a particular embodiment, the binder is an amorphous polyalphaolefin available from Eastman chemical company under the trade name EASTOFLEX. When used in combination with magnetic materials, amorphous polyalphaolefins exhibit excellent adhesion to printable substrates without the need for additional compositions. However, some polymeric materials require the addition of other substances such as tackifying resins, plasticizers, and the like to provide adequate adhesion. The addition of low molecular weight plasticizers and/or tackifying resins can also alter the rheological properties and/or reduce the melt viscosity of the magnetic composition, thereby improving the processability of the magnetic composition.

Polymeric materials suitable for use in the present invention may be used together. In addition, other polymers not specifically described herein may also be used in the present invention. The above series of examples is merely illustrative, and the scope of the present invention is not limited to these examples. Those skilled in the art will be aware of the wide variety of polymeric materials that can be used in the present invention.

Tackifying resins are available from a variety of sources, including many of the companies mentioned above, and also include the hydrocarbon tackifying resins available under the trade name easotac from Eastman chemical company; petroleum hydrocarbon resins available from ExxonMobil under the trade name ESCOREZ; polyterpene resins with the trade names PICCOTAC and PICCOLYTE manufactured by Hercules; petroleum hydrocarbon resins available from Goodyear corporation under the trade name WINGTAC; hydrocarbon resins under the trade name REGALREZ and hydrogenated aromatic resins under the trade name REGALITE, etc., produced by Hercules corporation.

Plasticizers are available from many sources, including plasticizing oils, which are typically produced from petroleum sources and are therefore available from a variety of petroleum companies.

Waxes may sometimes also be added to the magnetic composition to reduce melt viscosity and/or modify rheological properties.

Other ingredients that may also be used include (but are not limited to): antioxidants, dyes or pigments, ultraviolet absorbers, and the like. Those skilled in the art are familiar with these useful ingredients, which generally do not adversely affect the physical properties of the magnetic composition, so long as they are added in low concentrations.

The above-described series of materials is merely illustrative and is by no means intended to exclude other materials that may be used in the present invention, nor is the scope of the present invention limited to the above-described materials.

The amount of binder required between the printable substrate and the magnetic composition will vary depending on the particular application and printable substrate used. If the printable substrate is a fibrous material such as paper, the magnetic composition is required to have sufficient adhesion to remove the fibers from the printable substrate. But the inability to remove the fibers does not mean that the adhesion is weak. For example, not delaminating may indicate that sufficient adhesion has been achieved. Other types of substrates, such as fabric, plastic or metal substrates, may require that the magnetic layer and the printable substrate layer do not peel easily or delaminate.

The strength of the bond between the magnetic layer and the printable substrate can be determined by methods known in the art, for example using 180 ° or 90 ° peel methods. These methods are found in ASTM test methods. The amount of force required to peel the magnetic layer from the substrate depends on the end use and the printable substrate. In some applications, a peel force of 200 to 400 g/inch is sufficient, with 400-450 g/inch being the upper limit, and in some applications a peel force as high as 1000-1500 g/inch or more may be required. For example, for thermoset polymer compositions, peel forces can be up to 1000-1500 g/inch or more.

The magnetic composition produced requires little or no surface tackiness at ambient temperature. The adhesives and mixtures thereof are very shear rate sensitive and exhibit Bingham plastic flow characteristics. In the hot melt state, the viscosity can be as low as 4000cp or as high as 200,000cp at 300F (about 150℃.). Since temperature is an important factor in viscosity, extrusion coating at temperatures up to about 600-650F (about 315-345℃) melt temperature is not difficult to achieve.

The temperature at which the magnetic composition is applied to the substrate is very different from the temperature in the extruder. After the magnetic composition exits the extruder and the coating die to form the magnetic layer, a significant degree of cooling may have been performed to coat the formed magnetic layer onto the printable substrate layer. The magnetic composition is maintained at an elevated temperature such that there is sufficient bond strength between the magnetic layer and the printable substrate layer.

The magnetic material and thermoplastic binder and/or other ingredients are mixed at elevated temperatures using standard thermoplastic mixing equipment, such as extruders, Baker Perkins mixers, Banbury mixers, single or twin screw extruders, Farrell continuous mixers, and high shear mixing equipment.

The magnetic mixture may be formed into a form, such as a bar, pellet, or any form known in the art suitable for feeding to an extruder or other melt processing equipment, and then shipped to a coating plant. The coating manufacturer will melt the magnetic mixture at the coating station using a high pressure single screw extruder or other device and apply pressure to pass the magnetic mixture through a coating die such as a slot die, rotary screen or die or other such coating die. For example, extruders and other hot melt equipment may supply the magnetic composition directly to the coating die. During extrusion and other melt processing of the magnetic composition, the temperature is high enough to melt, i.e., change the magnetic composition to a melt or liquid state.

In another embodiment of the invention, the various ingredients may be fed separately to the extruder in other forms such as pellets, slats, and the like. For example, if more than one thermoplastic binder material is used, they need not be mixed in the form of pellets or strips prior to being fed to the extruder. They may be fed separately to the extruder in the form of pellets or strips.

The coating manufacturer may use a variety of coating methods known in the art. Suitable methods of applying the magnetic composition to the printable substrate include (but are not limited to): slot die coating, roll coating, reverse roll coating, knife over roll gravure coating, reverse direct gravure coating, air knife coating, slot orifice coating, hot wire screen printing, and the like.

In one embodiment of the invention, slot die coating is used in conjunction with a single screw extruder.

In another embodiment of the present invention, a process known in the industry as "flex-o-press" is used. The term "rotary printing" as used herein refers to a four roll coating process. The first roller is used for heating and is usually rotated at half the speed of the second roller. The second roller is used to transport the thermoplastic/magnetic material mixture. The third roll is a roll-to-plate roll which is a silicone rubber coated roll and has a surface designed with a pattern of raised areas to enable the magnetic composition of the present invention to be applied to the printable substrate in a predetermined pattern. There is slight contact between the third roll and the second roll and the thermoplastic/magnetic material mixture is transferred to the fourth roll. See "Roll coating," R.T. Schorenberg, Encyclopedia of Modern plastics, 1984, 1985, page 202, 203 (Roll coating by R.T. Schorenberg, Modern plastics Encyclopedia, 1984, 1985, pp.202-203), which is incorporated herein by reference in its entirety. Another valuable reference is the "Handbook of coating technology", second Edition, written by Satas and Tracton, published by Marcel Dekker, 2001(coatings technology Handbook, 2nd Edition, Satas and Tracton, Marcel Dekker, Inc., 2001), which is also incorporated herein by reference. The processing equipment includes a chill roll in order to increase the cooling and solidification rate of the resulting magnetic composition comprising at least a magnetic material and a thermoplastic material. This facilitates faster processing of the finished composition into rolls or sheets.

The linear speed of rotation may vary up to 500 feet per minute or more. Except that the prior methods allowed line speeds of only 40-80 feet per minute. The line speeds that can be used with the present invention are therefore much faster than currently used methods. The line speed is limited by the extruder and other coating equipment of the present invention, as well as by the following factors: the type and size of die, nozzle or other coating die used, the pressure used, the viscosity of the magnetic composition, and the temperature during coating (as is well known to those of ordinary skill in the art).

Any method of applying a thermoplastic magnetic composition directly to a printable substrate at an elevated temperature that causes it to become flexible or plastic in form can be used in the present invention. Using this method of the present invention, the thermoplastic magnetic composition can be directly attached to the target substrate in a variety of desired shapes or forms without the need for additional adhesives. Thus, the magnetic layer produced may be formed and bonded to the printable substrate in one unit or single step.

In contrast, the previous method requires multiple steps: the magnetic assembly is formed by forming a magnetic layer, cutting the magnetic layer, and then gluing the magnetic layer to a substrate using an additional layer of cement. The magnetic layer may be supplied in the form of a roll, or may be pre-cut into a desired form depending on the use of the magnetic layer, and then bonded to the printable substrate. The present invention allows the entire magnetic assembly to be formed in one step. Thus, the method of the present invention is more efficient than previous methods.

Using the method of the present invention, the adhesive and magnetic material are applied to the printable substrate at elevated temperatures when the thermoplastic adhesive is in a pliable or plastic form. The final form of the magnetic composition in the present invention is at a sufficiently high temperature to allow sufficient wetting and adhesive strength between the magnetic composition and the printable substrate. The amount of adhesion will of course also depend on the adhesive composition used. Some adhesives may provide greater bond strength than others.

In the method of the present invention, the substrate to which the magnetic composition is to be bonded comprises: paper or paper-like products, cardboard, plastic or polymeric materials, metal, release liners (e.g., silicone release liners), fabrics, and the like. Combinations of these substrates may also be used. For example, in some embodiments, the release liner may be used in combination with another printable substrate, each on one side of the magnetic layer. A magnetic assembly comprising a printable substrate layer and a magnetic layer may be peeled from a releasable tape in use.

The desired application temperature depends on a variety of factors including the melting temperature of the thermoplastic binder, the viscosity of the resulting magnetic composition, and the like. The melting temperature and viscosity will vary depending not only on the type of binder used, but also on the various other ingredients that may be added to the magnetic composition as described above. The higher the viscosity or melting temperature, the higher the temperature required to successfully apply the magnetic composition. Generally, the temperature at which the thermoplastic material is applied is about 275-375 deg.F (about 135-190 deg.C), and there are also higher or lower temperature conditions than this. For example, very low viscosity thermoplastic coatings can be applied at temperatures as low as about 190F (about 90℃). Some thermoplastic materials may be applied at temperatures as high as about 400F (about 205℃) or higher, for example polyamide materials are typically applied at temperatures of about 400F. And may even exceed 650 deg.f. However, for most thermoplastic materials, higher temperatures result in faster material degradation. One commonly used coating temperature range is about 325 ℃ and 375 ℃ F. (about 205 ℃ and 190 ℃ C.), and most commonly 350 ℃ F. (about 175 ℃ C.). In one embodiment of the invention, a polypropylene material is used and coated at temperatures in excess of 400F (205℃). However, when using extrusion techniques, the polyethylene is generally extruded at a temperature greater than 600 ° f (306 ℃) and at a high extrusion rate.

The temperature at which the coating is applied is sufficiently high to reduce the viscosity of the thermoplastic material so that the thermoplastic material adheres strongly to the printable substrate. This includes penetrating or "wetting out" the surface of the substrate to be coated. The thermoplastic material should have sufficient adhesion to the substrate to avoid delamination of the substrate.

The magnetic composition may be conveniently applied in a thin layer using the method of the present invention, having a thickness of about 50 to 765 microns (about 0.002 to 0.030 inches, about 2 to 30 mils), preferably about 50 to 510 microns (about 0.002 to 0.020 inches, about 2 to 20 mils), and most preferably about 50 to 305 microns (about 0.002 to 0.012 inches, about 2 to 12 mils). The present invention can also be applied to thinner layers of the binder/magnetic material mixture. In contrast, previous extrusion and rolling methods have been unable to apply magnetic layers having thicknesses less than 4-8 mils, and typically greater than 10 mils.

In one embodiment of the invention, the magnetic composition may be applied as a tape onto a printable substrate at elevated temperatures to a plasticized state. The magnetic composition may be applied to the substrate in the form of a strip of the same length and width as the printable substrate, or may be applied intermittently to the substrate in preselected discrete regions. Alternatively, several strips of magnetic composition may be applied to the substrate simultaneously or intermittently to form a discontinuous pattern. The production line may be equipped with equipment to press the applied tape against the printable substrate. For example, chill rolls may be used for this purpose.

The surface of the belt may also be contacted by a magnetized roll which smoothes, cools and magnetizes the surface of the belt. When subjected to the above steps, while the tape is still liquid, an effect of enhancing magnetic properties called "orientation" is provided. Tapes can be used with thicknesses of about 50-510 microns (about 0.002-0.020 inches).

In a broad sense, the method of the present invention allows the magnetic composition to be formed and applied to the printable substrate in a single step. The width, thickness and length of the magnetic layer may each be as large as desired, and may be such as to cover the entire printable substrate, be dimensionally coextensive with the printable substrate, or cover only some of the spaced-apart regions of the substrate. In addition, the magnetic composition may be applied by patterning a silicone rubber-coated roller such as described above (e.g., a rotary press).

Further, the magnetic composition may be formed and attached to the printable substrate as a finished product substantially simultaneously. Its thickness and width, or thickness, width and length, may become its final fixed form. As used herein, "substantially simultaneously" means occurring in the same manufacturing process.

In the production process, the magnetic composition may be fully magnetized by applying a magnetic field along the entire width of the substrate on a production line after the magnetic composition is applied to the printable substrate. Sometimes the magnetization step may be performed after printing or after the article is cut, die cut or punched to the desired size and shape as described below.

Alternatively, the magnetization step may be carried out while the thermoplastic binder is heated to an elevated temperature. This can result in orientation of the magnetic particles, which results in a significant increase in magnetic induction compared to the same article magnetized at ambient temperature. See Sawa 4022701 and Ito 6190513.

In some cases, indicia (i.e., the content to be printed) may be printed onto the printable substrate before or after the printable substrate is attached to the magnetic layer. For ease of production, it may be desirable to print after the printable substrate is attached to the magnetic layer. But sometimes it is not necessary to print on a printable substrate. For example, magnetic note sheets are produced without printing. This allows the user to subsequently write their notes or notification content.

Once the content to be printed has been printed onto the printable substrate, a paint, film or other protective surface may be applied to the surface of the printed substrate to improve its appearance. These or similar materials may also be applied to the outer surface of the magnetic layer, if necessary, to prevent the assembly from accidentally "sticking" to each other or to other substrates.

Once the entire magnetic assembly has been produced as a roll or sheet, it may be cut, punched, die cut, etc. into the desired shape. Laser cutting is one method by which sheets and webs can be formed into a wide variety of articles.

Fig. 1 shows a magnetic assembly 10 made by the method of the present invention. The magnetic layer 12 is attached to the printable substrate layer 14 without the use of other adhesive layers.

FIG. 2 shows one embodiment 10 of the present invention in which a magnetic layer 14 is applied to a region of a printable substrate 12.

Figure 3 shows another embodiment 10 of a magnetic assembly of the present invention in which the magnetic layer 14 and printable substrate layer 12 are substantially coextensive in length 16 and width 18.

In one embodiment of the invention, the magnetic assembly is a one-layer magnetic marker assembly comprising a magnetic layer 14 and a printable substrate layer 12 having desired indicia or information printed thereon.

Figure 4A shows a magnetic marker assembly 10 of the present invention comprising a printable substrate layer 12 and a magnetic layer 14 attached thereto. The magnetic layer is also attached to a release liner 26. The release liner includes a substrate comprising silicone. This can be accomplished in any manner known in the art, such as by using a removable pressure sensitive adhesive, such as a removable hot melt adhesive or a dry peelable adhesive, although in some embodiments, the use of an adhesive is not required. Furthermore, the combination comprising the printable layer 12, the magnetic layer 14, and the release liner 26 may be attached to an object such as a package, cup, book, magazine, or other object 22 using a pressure sensitive adhesive or a dry release adhesive (not shown). Such a magnetic assembly 10 may be used for commercial advertising and promotional purposes.

In one embodiment, the magnetic assembly is a one-layer magnetic marker assembly. The magnetic marker assemblies are releasably attached to the base article by well-known adhesives such as water-based adhesives, hot melt adhesives or other types of adhesives. Such suitable adhesives are pressure sensitive adhesives, more suitably removable pressure sensitive adhesives, although such pressure sensitive adhesives may be of the permanent or semi-permanent type. By its nature, a release liner is difficult to attach and therefore the type of adhesive employed is not limited. Thus, depending on the release liner used, either a semi-permanent or permanent adhesive or a non-pressure sensitive adhesive may be used. The choice of adhesive is known to those skilled in the art. In any event, however, the adhesive is required to be more adhesive to the base article than to the release liner so that the magnetic assembly is easily removed from the base article. After the magnetic assembly is removed, it may be attached to a magnetic surface such as a refrigerator, cabinet, magnetic bulletin board or billboard, for the purpose of displaying the printed indicia.

One embodiment of an adhesive suitable for use herein is an ethylene-vinyl acetate copolymer latex, more specifically, an aqueous dispersion containing 60% by weight solids comprising 22.4% by weight ethylene and 77.6% by weight vinyl acetate. The adhesive may also contain a crosslinking agent and/or an inorganic peroxide, as well as other ingredients well known in the art.

The base article may be made of any desired material and may have any configuration so long as the magnetic marker assembly is releasably attached thereto. In the above embodiments, the adhesive is located between the release liner and the base article.

Figure 4B shows another embodiment where the printable substrate layer 12 also has an upper cover laminate 30 thereon that has dimensions on the printable substrate layer 12 that are at least substantially equal in length and width to the magnetic layer (not shown). The upper cover stack is preferably a layer of transparent polymeric film material. In this embodiment, no adhesive is required between the magnetic layer and the release liner, or between the release liner and the object 22. The upper cover laminate has perforations that are substantially the same length and width in size as the printable substrate layer 12 and the magnetic layer (shown) to allow for easy removal of the magnetic assembly comprising the printable substrate layer and the magnetic layer. Any number of holes may be used. It is desirable to have at least two apertures on opposite sides of the assembly. Further description of this embodiment can be found in relation to the detailed description of fig. 11-13.

The upper overlay stacks may have substantially the same length and may be slightly wider or substantially the same width and different lengths. All sides, or opposite sides, of the overlying laminate may be secured to the base article using an adhesive. For example, such adhesive may be applied as a thin strip, dot, or other form. The adhesive is a removable, permanent or semi-permanent pressure sensitive or non-pressure sensitive adhesive. The preferred adhesive is a permanent adhesive. However, the choice of the type of adhesive is critical, preferably in accordance with the requirements of the user. It is primarily contemplated that the magnetic assembly may be removed from the overlying layer stack, as well as from the base article. This may be done, for example, by using a perforation line in the overlying stack, where a portion of the overlying stack remains on the base article and a portion remains on the magnetic assembly. If these lines of perforations are used, it is preferred to place the holes inside the adhesive.

These lines of perforations can then be broken to remove the magnetic assembly from the base article. In the embodiments described above that use an overlying laminate, the magnetic assembly may be removably attached to a release liner using an adhesive, but the adhesive is not required because the overlying laminate secures the magnetic assembly to the base article. After removal, the magnetic assembly can attach itself to a magnetic surface, such as a refrigerator, cabinet, magnetic billboard, notification sign, or the like.

In another alternative embodiment, the magnetic assembly 10 is packaged in a film, such as a polyolefin or polyolefin copolymer based film, sialon, polyester film, or other such film. One use like this is in the bookbinding industry or the pressure sensitive adhesive industry, such as magazine binding, where advertisements or samples are temporarily attached to magazines or books. The magnetic assembly 10 is self-attaching to a magnetic surface, such as a refrigerator or file cabinet, after removal from a package, book, magazine, or the like.

Fig. 5 shows a magnetic assembly 15 of the present invention from a large sheet or roll prior to singulation into smaller pieces, with the magnetic layer 14 having substantially the same length 16 and width 18 as the printable substrate layer 12. In this embodiment. A single sheet such as a label, business card, or the like (not shown) has been printed on this large sheet form of printable substrate layer 12. Individual magnetic sheets 24 may be removed from the top surface along perforation lines 26 by cutting, stamping, punching, or the like.

Shown in fig. 6 is another embodiment as shown in fig. 5, with the magnetic layer 14 being laminated in strips to regions of the printable substrate layer 12. In this embodiment, a top magnetic layer 14 is shown, and when cut along the perforation line 26, a magnetic assembly is obtained.

Several sheets can be joined together using a method similar to what is known in the industry as "perfect" binding. Using this method, sheets of printable substrate with magnetic layers are stacked or arranged in a stack, sandwiched together, and then bonded together with an adhesive. The adhesive is applied to an outer face of the stack or stack, which may also be referred to as the "spine". If a pressure sensitive adhesive is used, a covering may be applied to the spine to protect the adhesive properties of the adhesive. If a non-pressure sensitive adhesive is used, it is not tacky and the cover need not be used. The adhesive may be applied by spraying, rolling or other methods. In another embodiment, an adhesive is used to form and stack a sheet of magnetic sheets. And shrink-packed together. A stack or set of 20 magnetic sheets 10 is shown in fig. 7. Figures 8, 9, and 10 illustrate various embodiments in which the magnetic layer 14 is disposed on the printable substrate 12. In these embodiments, the printable substrate is a blank sheet of paper, which, of course, may be personalized or may have information printed thereon.

Figure 11 is a cross-sectional view of an embodiment of a layer of a magnetic assembly 50 produced in accordance with the present invention. The magnetic layer 14 is adhered to the printable substrate layer 12 without the use of an adhesive layer. There is a release liner 26, adjacent to the magnetic layer 14. In this embodiment, an upper cover stack 28 is employed to hold the assembly together. The upper cover laminate has lines of perforations 30 that can be used to remove the magnetic assembly 10 including the printable substrate layer 12 and the magnetic layer 14 from the release liner 26. In this embodiment, no adhesive is used to secure the release liner 26 to the magnetic layer 14. Figure 12 shows a top view of a perforation line 30 positioned on top overlay stack 28. This may also be on a large sheet form such as 60 shown in figure 13.

In a particular embodiment, the magnetic assembly described above is a magnetic marker assembly.

The assembly shown in fig. 11-13 has a four-layer structure with a cross-section as shown in fig. 11. No adhesive is used in this embodiment. The entire assembly includes the release liner 26, magnetic layer 14, printable substrate layer 12 and a transparent overlying laminate 28.

FIG. 14 shows another embodiment in which the applied magnetic layer 14 is in the form of spaced apart regions 15. This assembly is a two-layer structure, with only the printable substrate layer 12 and the magnetic layer 14. The printable substrate layer 12 has a perforation line 30 that substantially conforms to the boundary of each magnetic sheet region 15 so that the individual magnetic assemblies 10 of the present invention, including the printable substrate layer 12 and the magnetic layer 14, are easily removed from the sheet 60. The magnetic sheet 15 is directly attached to the printable substrate layer 12. Fig. 15 shows a top view of a large sheet of magnetic sheet as in fig. 14, showing the perforation lines 30 on the printable substrate layer 12 coinciding with individual magnetic sheets 15 to allow easy cutting of the magnetic sheets 15.

The above figures illustrate only some embodiments of the invention for illustrative purposes and do not limit the scope of the invention.

The method of the present invention, in which the magnetic composition is applied directly to the printable substrate, enables all other steps to be included in the overall manufacturing process of the present invention. Combinations of steps such as printing, coating and shaping the article by cutting, stamping, punching and the like may be included in the overall process.

Articles produced by this method include, but are not limited to, promotional tickets, greeting cards, postal cards, commercial advertising cards, magnetic commercial cards, designated reminders, announcements, advertisements, coupons, labels, calendars, schedules, travel notes, photo frames and other articles for informational purposes, all having a magnetic surface bonded to a printable surface that is capable of self-attaching to a metal surface for display.

Bulletin cards include bulletins such as baby bulletins, ceremonies, wedding anniversaries, evening meetings, "we have moved", and the like.

Promotional orders include items such as restaurant advertisements, automated services, veterinary clinics, real estate agents, lawn care services, insurance agents, and the like. These promotional tickets typically include a telephone number and an address. Adding a calendar further increases the chances of using it on a refrigerator.

Other examples include schedule, such as sports meeting schedule, school calendar, etc.

These articles are for illustrative purposes only and are not intended to limit the scope of the present invention. The magnetic assemblies of the present invention have numerous uses and those skilled in the art will understand how to use these magnetic assemblies and their modifications, which are not described herein.

The product can be delivered by direct mail, or added to magazines and newspapers.

The magnetic assemblies of the present invention may also be used in children's toys such as magnetic paper dolls or character images, letters and numbers that are self-adhering to magnetic billboards.

The above disclosure is intended to be illustrative and not exhaustive. These descriptions may suggest many variations and alternative embodiments to those skilled in the art, which are encompassed by the present claims, where "includes" means "including, but not limited to". Those skilled in the art will recognize that there are numerous other embodiments of the equivalents described herein and that the equivalents are encompassed by the claims.

Furthermore, the features presented in the dependent claims may each be combined with other features in other ways within the scope of the invention, so that the invention is to be understood as also relating to embodiments having other possible combinations of the features of the dependent claims.

Other embodiments equivalent to one of the specific embodiments to be described herein will be understood by those skilled in the art and are therefore intended to be encompassed by the claims.

The following non-limiting examples serve to further illustrate the invention

Examples

Example 1

Amorphous polypropylene P #1023 from Eastman Chemical co. was mixed with ferrite powder HM410 Starbond from hoosier magnetics in a ratio of 85 wt% polypropylene and 15 wt% ferrite particles. The resulting mixture was coated into a tape at 325-375 deg.F (about 165-190 deg.C) on a printable paper substrate using an extruder/slot die. The thickness of the tape varied from 75 microns to 305 microns (0.003-0.012 inches).

The speed range for the spaced apart strip coatings was 250 and 500 feet per minute, and for the entire covered strip coating the speed range was about 80 feet per minute.

Claims (41)

1. A method of forming a magnetic assembly of at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, the method comprising the steps of:

a) providing a magnetic composition that is hot-melt at elevated temperatures, the hot-melt magnetic composition comprising 75-95 wt.% of at least one magnetic material and 5-25 wt.% of at least one thermoplastic binder;

b) forming the magnetic composition into the magnetic layer at an elevated temperature;

c) the hot melt magnetic composition is applied directly to a printable substrate layer when it is in a flexible state at elevated temperatures.

2. The method of claim 1, further comprising subjecting the magnetic assembly to a strong magnetic field sufficient to produce a permanent magnetic effect in the assembly when the magnetic composition is at an elevated temperature or when the magnetic composition is cooled to room temperature.

3. The method of claim 1, wherein the at least one magnetic material is present in a concentration sufficient to cause the magnetic assembly to self-adhere to a substrate comprising a ferromagnetic material.

4. The method of claim 1 wherein said applying step b) secures said magnetic layer to said printable substrate layer at the thickness and width of the final article or said applying step b) secures said magnetic layer to said printable substrate layer at the thickness, width and length of the final article.

5. A method of forming a mat product comprising forming a plurality of sheet magnetic assemblies by the method of claim 1 and laminating the sheet assemblies together to form a laminated mat.

6. The method of claim 5, wherein said plurality of sheet assemblies are bonded together by adhesive or shrink wrapping.

7. The method of claim 1, wherein said coating temperature is between 90 ℃ and 205 ℃.

8. The method of claim 1, wherein said forming comprises a step selected from the group consisting of extrusion, roll coating, gravure coating, screen printing, and slot die coating.

9. The method of claim 1, wherein the magnetic material has the general formula:

M²⁺O6Fe₂O₃

wherein M represents a divalent metal.

10. The method of claim 9, wherein the divalent metal is barium, strontium, lead or mixtures thereof.

11. The method of claim 1, wherein the at least one thermoplastic binder comprises at least one component selected from the group consisting of natural rubber, block copolymers, polyolefins, polyesters, polyamides, polyurethanes, and copolymers or mixtures thereof.

12. The method of claim 11, wherein the polyolefin is a polyalphaolefin.

13. The method of claim 1, wherein the at least one thermoplastic binder comprises at least one amorphous polypropylene, at least one interpolymer of ethylene and at least one alpha-olefin, at least one copolymer of ethylene and vinyl acetate, at least one copolymer of ethylene and an acrylate, at least one copolymer of ethylene and a methacrylate, at least one copolymer of ethylene and n-butyl acrylate, or a mixture thereof.

14. The method of claim 1, wherein the at least one thermoplastic binder comprises a mixture of ethylene vinyl acetate copolymers.

15. The method of claim 1, wherein the at least one magnetic layer has a thickness of 50 to 765 microns.

16. The method of claim 1 wherein said magnetic composition is applied to said printable substrate in the form of at least one tape.

17. The method of claim 1 wherein the magnetic layer is further coupled to a release liner.

18. The method of claim 17, wherein the object is a magazine, book, food packaging bag, beverage packaging box, envelope, or box.

19. The method of claim 17 wherein said magnetic assembly further comprises a cover laminate on said printable substrate layer.

20. The method of claim 19 wherein said cover laminate is perforated with approximately the same dimensions as said magnetic assembly.

21. The method of claim 1 wherein said magnetic layer is continuous with said printable substrate layer or said magnetic layer is applied to said printable substrate layer in a discontinuous pattern.

22. The method of claim 1 wherein said magnetic layer has the same length and width as said printable substrate layer.

23. The method of claim 1, wherein there is sufficient adhesion between the magnetic layer and the printable substrate layer without an additional adhesive layer between the magnetic layer and the printable substrate layer.

24. An article capable of adhering to a magnetic surface having at least one printable substrate layer and at least one magnetic layer, said magnetic layer comprising 75 to 95 weight percent of at least one magnetic material and 5 to 25 weight percent of at least one thermoplastic binder, said thermoplastic binder comprising at least one amorphous polypropylene.

25. The article of manufacture of claim 24, comprising:

a) a first magnetic layer comprising 5-25 wt% of at least one thermoplastic binder and 75-95 wt% of at least one magnetic material;

b) a second layer of printable material.

26. The method of claim 25, wherein the article is in the form of a reminder slip, greeting card, postal card, coupon, label, business card, advertisement, calendar, receipt, schedule, or promotional card.

27. The article of claim 25, wherein the first layer has a thickness of 50 to 765 microns.

28. The article of claim 25, wherein the at least one adhesive composition comprises at least one component selected from the group consisting of natural rubber, block copolymers, polyolefins, polyesters, polyamides, polyurethanes, and copolymers or mixtures thereof.

29. The article of claim 28, wherein the polyolefin is a polyalphaolefin.

30. The article of claim 25, wherein said at least one binder is amorphous polypropylene or a copolymer thereof, an interpolymer of ethylene and at least one alpha-olefin, a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and n-butyl acrylate, a copolymer of ethylene and an acrylate, a copolymer of ethylene and a methacrylate, or a mixture thereof.

31. The article of claim 25, wherein said magnetic material is at least one compound having the formula: m²⁺O6Fe₂O₃Wherein M represents a divalent metal.

32. The article of claim 31, wherein the divalent metal is barium, strontium, lead, or mixtures thereof.

33. A magnetic composition comprising:

a) 5-25% by weight of at least one polyalphaolefin binder, said polyalphaolefin being amorphous polypropylene or a propylene copolymer or propylene terpolymer; an interpolymer of ethylene and at least one alpha-olefin; or a mixture of these or a mixture of them,

b)75-95 wt% of at least one magnetic material.

34. The composition of claim 33, wherein the magnetic material has the formula:

M²⁺O6Fe₂O₃

wherein M represents a divalent metal.

35. The composition of claim 34, wherein the divalent metal is barium, strontium, lead or mixtures thereof.

36. A method of forming a magnetic assembly comprised of at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, said method comprising extruding at elevated temperature a magnetic composition comprising 70 to 95 weight percent of at least one magnetic material and 5 to 30 weight percent of at least one thermoplastic binder selected from the group consisting of natural rubber, block copolymers, polyolefins, and copolymers or mixtures thereof onto a printable substrate layer.

37. The method of claim 36, wherein the polyolefin is a polyalphaolefin.

38. A method according to claim 36, wherein the at least one thermoplastic binder is an ethylene vinyl acetate copolymer.

39. A method of forming a mat article comprising a plurality of magnetic sheet assemblies having at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, said method comprising the steps of:

a) providing a molten magnetic composition comprising 70-95 wt.% of at least one magnetic material and 5-30 wt.% of at least one thermoplastic binder;

b) applying the magnetic layer directly to a printable substrate layer while in a flexible state at an elevated temperature to form a magnetic assembly;

c) forming the magnetic assembly in b) into a plurality of magnetic sheet assemblies;

d) laminating the sheet assemblies together to form a stacked mat.

40. The method of claim 39, further comprising bonding the sheet assemblies together.

41. A method of forming a magnetic assembly of the type consisting of at least one magnetic layer having a thickness, width and length and at least one printable substrate layer having a thickness, width and length, said method comprising the steps of:

a) providing a molten magnetic composition comprising 70-95 wt.% of at least one magnetic material and 5-30 wt.% of at least one thermoplastic binder;

b) applying the magnetic layer directly to a printable substrate layer when the magnetic layer is in a flexible state at elevated temperatures

c) The magnetic layer is magnetized at a high temperature.