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WO2009043948A1 - Method for conditioning mineral materials such as safety additives - Google Patents

Method for conditioning mineral materials such as safety additives Download PDF

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Publication number
WO2009043948A1
WO2009043948A1 PCT/ES2008/000602 ES2008000602W WO2009043948A1 WO 2009043948 A1 WO2009043948 A1 WO 2009043948A1 ES 2008000602 W ES2008000602 W ES 2008000602W WO 2009043948 A1 WO2009043948 A1 WO 2009043948A1
Authority
WO
WIPO (PCT)
Prior art keywords
inorganic material
paper
grinding
carried out
conditioned
Prior art date
Application number
PCT/ES2008/000602
Other languages
Spanish (es)
French (fr)
Inventor
Antonio Olmos Ruiz
Jose Mendia Aguilar
Javier Baraja Carracedo
Juan Antonio Rubio Sanz
Miguel Angel Rodriguez Barbero
Jose Francisco Fernandez Lozano
Original Assignee
Fabrica Nacional De Moneda Y Timbre - Real Casa De La Moneda
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fabrica Nacional De Moneda Y Timbre - Real Casa De La Moneda filed Critical Fabrica Nacional De Moneda Y Timbre - Real Casa De La Moneda
Publication of WO2009043948A1 publication Critical patent/WO2009043948A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D15/00—Printed matter of special format or style not otherwise provided for
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7701—Chalogenides
    • C09K11/7703—Chalogenides with alkaline earth metals
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7774—Aluminates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/40—Agents facilitating proof of genuineness or preventing fraudulent alteration, e.g. for security paper
    • D21H21/44—Latent security elements, i.e. detectable or becoming apparent only by use of special verification or tampering devices or methods
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency

Definitions

  • the invention belongs to the field of inorganic materials used as security elements in paper. More specifically, the invention relates to a method for conditioning said inorganic materials as safety additives, as well as to the inorganic conditioned material thus obtained, to a safety paper comprising said inorganic material conditioned in its composition and to the use of the material inorganic conditioning for the manufacture of security paper.
  • the operative form in the preparation of the products is always the same: once the physical property to be developed in the document is known, the raw material is defined with the appropriate additives or dopants to design the response of so that it stays in a desired range, whether of frequencies, electric field, magnetic permeability, etc.
  • the active material obtained by synthesis, whose properties of evaluable behavior are known, it is necessary to process it to achieve the precise characteristics to be able to add it to the paper.
  • US 6344261 describes a series of inorganic materials with luminescent capacity useful as safety elements.
  • the patent also describes the preparation of said materials which, after their synthesis, are incorporated directly into the paper pulp.
  • the direct incorporation of the powdered materials into the paper pulp results in an insufficient dispersion of the material in the paper that is desirable to improve.
  • the inventors of the present invention have developed a method for conditioning inorganic materials for incorporation into paper pastes This is based both on the use of suitable average particle sizes and on the prior dispersion of said particles in a conditioning solution.
  • the method of the present invention allows to obtain clearly improved and more homogeneous dispersions of the inorganic safety material in the paper pulp and therefore higher quality security papers.
  • the invention relates to a method for the conditioning of applicable inorganic materials as safety additives in paper comprising: a) Calcination and agglomeration of the inorganic material at a temperature of up to 1600 ° C,
  • inorganic material is any mineral substance commonly used as a paper safety additive. Normally these minerals have some physical property that allows them to act as such security elements. Inorganic materials used as safety elements are normally capable of being excited at certain wavelengths while emitting luminescence to different lengths.
  • the inorganic materials of the invention are minerals that comprise rare earths since these have the ability to excite in the visible spectral region and have a high level of emission intensity in the near-infrared spectral region.
  • the inorganic materials of the invention have a perovskite-like structure such as strontium titanate doped with praseodymium or other rare earths.
  • the inorganic material has a garnet-like structure such as ytrium aluminate doped with erbium or other rare earths.
  • the calcination and agglomeration of the inorganic material previously synthesized is carried out.
  • This heat treatment serves to improve certain aspects of the synthesized products such as their chemical stability, degree of crystallinity, their crystallite size and their state of agglomeration.
  • the treatment must be designed according to the material and synthesis method by which it has been synthesized although in general the calcination will be carried out at a temperature not exceeding 1600 0 C. In a preferred embodiment of the invention the calcination will be carried out between 800 and 1300 0 C.
  • the second stage of the process involves subjecting the agglomerated material to one or several grinding stages up to an average particle size within the range of 2 to 20 ⁇ m. These are sizes compatible with the paper preparation. On the one hand the particles cannot be greater than 20 ⁇ m so that they are perfectly integrated in the thickness of the sheet of the final paper and to avoid its location and identification because it is a security element. On the other hand, if the concentration of particles less than 2 ⁇ m is very high, the effectiveness of the product will be low since during the papermaking process, much of the material will be lost with the water. Therefore, the size ranges must be in a
  • the average particle size must be within the range of 3 to 7 ⁇ m.
  • the materials are densified, so that before the fine grinding until reaching the desired particle size, it is necessary to start with a previous or broken grinding, which can be carried out by techniques such as breaking the jaws, hammers or of roller. These types of treatments are done dry. In the case of soft agglomerates, high shear agitation systems can be used, taking advantage of this stage for the suspension of the material.
  • the last step of the method comprises the suspension of the material with the appropriate particle size in water in the presence of one or more dispersing agents.
  • the amount of dispersant must be determined according to the unit of active material to be processed. As a reference unit, the material surface that is the one that makes rheological sense should be used. Therefore, the amount of dispersing agent necessary for the suspension will depend on the specific surface area of the final product.
  • organic and inorganic dispersants are valid for the purposes of the present invention. As for the predominant dispersing effect, this may be steric in the case of ammonium or ionic polyacrylate, as in the case of sodium or mixed hexametaphosphate, such as in the case of polyethylene glycol. Both ammonium polyacrylate, such as sodium hexametaphosphate and polyethylene glycol represent the preferred dispersants of the invention although other dispersants may also be valid. Dispersants can be used individually or mixed together.
  • the method of the invention may include several optional steps depending on the type of material to be processed and the use that is intended to be given to the final conditioning solution.
  • the material to be agglomerated when it has the appropriate dimensions for calcination, it can be subjected to some previous grinding stage. This grinding can be performed by any of the techniques mentioned above.
  • the circumstance can be given that the conditioned material will be used immediately for the preparation of the paper, so that there would be no problem.
  • the application of the material is to be carried out later and the material must be stored or transported, it can be subjected to a drying stage to remove the water.
  • This drying stage can be carried out by means of a press filter or spray. This last technique is preferable.
  • Another aspect of the invention relates to the conditioned inorganic material obtainable according to the method of the invention.
  • the object of the invention is also a security paper comprising an inorganic conditioned material obtainable according to the method of
  • a final aspect of the invention refers to the use of a conditioned inorganic material according to the method of the invention in the preparation of security paper.
  • a luminescent active substance with a Perovskite-like structure consisting of Strontium titanate doped with Praseodymium, prepared as described in the work of H. Yamamoto, S. Okamoto and H. Kobayashi (Journal of Luminescence 100 (2002) 325-332).
  • the appropriate quantities of SrCO 3 , TiO 2 and PrCI 3 are homogenized in a dry ball mill and placed in a Cordierita-mullita crucible of low form and of 2 liters capacity.
  • Said crucible is introduced in an electric oven capable of reaching 1500 0 C. It is heated at a speed of 2 ° C / min to 800 0 C to achieve the decomposition of raw materials and subsequently the temperature is raised to 1300 0 C at a speed of 3 ° C / min. It is kept at said temperature for 120 min and cooled at a speed of 3 ° C / min. At 200 ° C the oven opens to accelerate cooling.
  • the obtained agglomerated powder is subjected to a previous grinding by means of a jaw crusher to a smaller size 0.5 mm
  • the powder thus obtained will be broken down into a continuous high shear agitation equipment, of the IKA brand.
  • a mixture consisting of 49.9% by weight of deionized water, 50% by weight of the substance to be deagglomerated and 0.1% of sodium hexametaphosphate is prepared.
  • Said mixture will be processed with the high shear agitator through the system of successive passes to ensure that all the material passes through the deagglomeration chamber. The passes continue until the particle size of the suspension, determined by dispersion of laser radiation indicates that 100% of the population is below 20 micrometers, and the average size between 2 and 7 micrometers, sizes compatible with the manufacture of paper.
  • the suspension thus obtained can be added to the formulation of the corresponding paper pulp.
  • a luminescent active substance with a garnet structure consisting of Ytrium aluminate doped with Erbium, prepared as described in the work of A. Leleckaite and A. Kareiva (Optical Materials 26 (2004) 123- 128). Suitable amounts of Y 2 O 3 , Er 2 O 3 and AI (NO 3 ) 3 .9H 2 O are processed as described below.
  • the Ytrium oxide is dissolved in a 0.2 molar solution of acetic acid at 65 0 C. To this solution is added Erbium oxide dissolved in acetic acid. Next, the Aluminum Nitrate, previously dissolved in water, is added. The whole is stirred for 3 hours at 65 0 C.
  • 1,2-ethanediol is added as a complexing agent.
  • the solution is concentrated by slow evaporation at 65 0 C until it becomes a transparent gel.
  • the gel is mechanically crushed and introduced into a Cordierita-mullita crucible of low shape and 2 liters capacity.
  • Said crucible is introduced in an electric oven capable of reaching 1500 0 C. It is heated at a speed of 2 ° C / min to 800 0 C where 120 min is maintained to achieve the decomposition and reaction of the raw materials.
  • the agglomerate thus obtained is subjected to a previous grinding by means of a jaw crusher up to a size smaller than 0.5 mm.
  • the obtained agglomerated powder is subjected to a previous grinding by means of a jaw crusher up to a size smaller than 0.5 mm.
  • the powder thus obtained will be broken down into a continuous high shear agitation equipment, of the IKA brand.
  • a mixture consisting of 54.7% by weight of deionized water, 45% by weight of the substance to be deagglomerated is prepared and 0.3% ammonium polyacrylate is added (Dolapix CE64 Zschimmer & Schwarz GMBH & Co KG) Said mixture will be processed with the high shear agitator through the system of successive passes to ensure that all the material passes through the breakdown chamber. The passes continue until the particle size of the suspension, determined by means of laser radiation dispersion, indicates that 90% of the population is below 100 micrometers.
  • the suspension is introduced into an attrition mill with zirconium oxide balls of 3 mm and thus processed to reach an average size between 3 and 7 micrometers, sizes compatible with papermaking.
  • the suspension thus obtained can be added to the formulation of the corresponding paper pulp.
  • an impeller atomizer is used, using an air pressure of 6 Kgr / cm 2 to move the impeller, an inlet air temperature of 35O 0 C.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Paper (AREA)

Abstract

The invention relates to: a method for conditioning inorganic materials such as safety additives, the resulting conditioned material, safety paper having a composition containing said conditioned inorganic material and the use of the conditioned inorganic material for the production of safety paper.

Description

MÉTODO DE ACONDICIONAMIENTO DE MATERIALES MINERALES COMO ADITIVOS DE SEGURIDAD METHOD OF CONDITIONING OF MINERAL MATERIALS AS SAFETY ADDITIVES
CAMPO DE LA INVENCIÓNFIELD OF THE INVENTION
La invención pertenece al campo de los materiales inorgánicos usados como elementos de seguridad en papel. Más concretamente, Ia invención se refiere a un método para el acondicionamiento de dichos materiales inorgánicos como aditivos de seguridad, así como al material inorgánico acondicionado así obtenido, a un papel de seguridad que comprende dicho material inorgánico acondicionado en su composición y al uso del material inorgánico acondicionado para Ia fabricación de papel de seguridad.The invention belongs to the field of inorganic materials used as security elements in paper. More specifically, the invention relates to a method for conditioning said inorganic materials as safety additives, as well as to the inorganic conditioned material thus obtained, to a safety paper comprising said inorganic material conditioned in its composition and to the use of the material inorganic conditioning for the manufacture of security paper.
ANTECEDENTES DE LA INVENCIÓNBACKGROUND OF THE INVENTION
El empleo de medios de identificación con objeto de asegurar Ia autenticidad de documentos o de objetos es muy antiguo y hoy en día se siguen empleando métodos, cada vez más sofisticados, con objeto de evitar falsificaciones. Estos métodos implican tanto al material soporte, como al conjunto del elemento a asegurar. Desde los diseños de logos hasta Ia incorporación de componentes electrónicos.The use of identification means in order to ensure the authenticity of documents or objects is very old and today, increasingly sophisticated methods are still used, in order to avoid forgery. These methods involve both the support material and the whole element to be secured. From logo designs to the incorporation of electronic components.
En el caso de documentos y de papel moneda es muy importante poder asegurar su autenticidad, por Io cuál, desde hace bastantes años se incorporan elementos que dificulten su falsificación. Se formulan composiciones de papel cada vez más complejas, se realizan marcas de agua, etc. Desde hace años se emplean componentes activos al papel, que en pequeñas proporciones son capaces de hacerlos activos a determinados estímulos ya sea radiación electromagnética, ya sean campos eléctricos, etc.In the case of documents and paper money, it is very important to be able to ensure their authenticity, which is why, for many years, elements that hinder their falsification have been incorporated. More and more complex paper compositions are formulated, watermarks are made, etc. Active components have been used for years to paper, which in small proportions are able to make them active at certain stimuli whether electromagnetic radiation, electrical fields, etc.
Ya desde los años 50 se describieron diversas formas de autentificación de documentos empleando medios ópticos, desde tarjetas de crédito (US 3679449), tarjetas de identificación (US 2704634), para evitar Ia fotocopia de documentos (US 3713861 ), documentos bancarios (US 3886083), tarjetas identificadoras (US 3928226), papel de seguridad (US 4183989).Since the 50s, various forms of authentication of documents using optical means, from credit cards (US 3679449), identification cards (US 2704634), to avoid the photocopy of documents (US 3713861), bank documents (US 3886083), identification cards (US 3928226), security paper (US 4183989).
Se han empleado distintos métodos de autentificación como evitar fotocopias generando emisiones fluorescentes, reflejando Ia radiación incidente, aportando partículas magnéticas, etc. En el fondo todo ello consiste en desarrollar alguna propiedad física, normalmente, en algún aditivo o recubrimiento a aplicar al documento de seguridad.Different authentication methods have been used such as avoiding photocopies generating fluorescent emissions, reflecting the incident radiation, providing magnetic particles, etc. In the end, all this consists in developing some physical property, normally, in some additive or coating to be applied to the security document.
La forma operatoria en Ia preparación de los productos (documentos de valor soportados sobre papel) es siempre Ia misma: una vez conocida Ia propiedad física a desarrollar en el documento, se define Ia materia prima con los aditivos o dopantes adecuados para diseñar Ia respuesta de forma que ésta se mantenga en un rango deseado, ya sea de frecuencias, campo eléctrico, permeabilidad magnética, etc. No obstante, el material activo, obtenido mediante síntesis, cuyas propiedades de comportamiento evaluable son conocidas, es necesario procesarlo para alcanzar las características precisas para poder adicionarlo al papel.The operative form in the preparation of the products (value documents supported on paper) is always the same: once the physical property to be developed in the document is known, the raw material is defined with the appropriate additives or dopants to design the response of so that it stays in a desired range, whether of frequencies, electric field, magnetic permeability, etc. However, the active material, obtained by synthesis, whose properties of evaluable behavior are known, it is necessary to process it to achieve the precise characteristics to be able to add it to the paper.
La patente US 6344261 describe una serie de materiales inorgánicos con capacidad luminiscente útiles como elementos de seguridad. La patente describe, asimismo, Ia preparación de dichos materiales que, tras su síntesis, son incorporados directamente a Ia pasta de papel. Sin embargo, Ia incorporación directa de los materiales pulverizados a Ia pasta de papel da lugar a una dispersión insuficiente del material en el papel que es deseable mejorar.US 6344261 describes a series of inorganic materials with luminescent capacity useful as safety elements. The patent also describes the preparation of said materials which, after their synthesis, are incorporated directly into the paper pulp. However, the direct incorporation of the powdered materials into the paper pulp results in an insufficient dispersion of the material in the paper that is desirable to improve.
Los inventores de Ia presente invención han desarrollado un método para el acondicionamiento de materiales inorgánicos de cara a su incorporación a pastas de papel. Éste se basa tanto en el uso de tamaños medios de partículas adecuados como en Ia dispersión previa de dichas partículas en una solución acondicionadora. El método de Ia presente invención permite obtener dispersiones netamente mejoradas y más homogéneas del material inorgánico de seguridad en Ia pasta de papel y por tanto papeles de seguridad de mayor calidad.The inventors of the present invention have developed a method for conditioning inorganic materials for incorporation into paper pastes This is based both on the use of suitable average particle sizes and on the prior dispersion of said particles in a conditioning solution. The method of the present invention allows to obtain clearly improved and more homogeneous dispersions of the inorganic safety material in the paper pulp and therefore higher quality security papers.
DESCRIPCIÓN DETALLADA DE LA INVENCIÓNDETAILED DESCRIPTION OF THE INVENTION
En primer lugar, Ia invención se refiere a un método para el acondicionamiento de materiales inorgánicos aplicables como aditivos de seguridad en papel que comprende: a) Calcinación y aglomeración del material inorgánico a una temperatura de hasta 1600° C,In the first place, the invention relates to a method for the conditioning of applicable inorganic materials as safety additives in paper comprising: a) Calcination and agglomeration of the inorganic material at a temperature of up to 1600 ° C,
b) Someter al material calcinado y aglomerado de a) a una o varias etapas de molienda hasta un tamaño medio de partícula de entre 2-20 μm,b) Subject the calcined and agglomerated material of a) to one or several grinding stages up to an average particle size between 2-20 μm,
c) Suspensión del material de b) en una solución acuosa con uno o más dispersantes,c) Suspension of the material of b) in an aqueous solution with one or more dispersants,
donde, opcionalmente, antes de Ia etapa a), puede llevarse a cabo otra etapa de molienda.where, optionally, before stage a), another grinding stage can be carried out.
En el contexto de Ia presente invención, material inorgánico es toda aquella sustancia mineral utilizada habitualmente como aditivo de seguridad para papel. Normalmente estos minerales tienen alguna propiedad física que les permite actuar como tales elementos de seguridad. Los materiales inorgánicos usados como elementos de seguridad son normalmente capaces de excitarse a ciertas longitudes de onda emitiendo a su vez luminiscencia a otras longitudes diferentes. Los materiales inorgánicos de Ia invención son minerales que comprenden tierras raras ya que éstas tienen Ia capacidad de excitarse en Ia región espectral visible y tienen un alto nivel de intensidad de emisión en Ia región espectral cercana al infrarrojo. En una realización preferida los materiales inorgánicos de Ia invención poseen una estructura tipo perovskita como por ejemplo el titanato de estroncio dopado con praseodimio u otras tierras raras. En otra realización preferida el material inorgánico tiene una estructura de tipo granate como por ejemplo el aluminato de ytrio dopado con erbio u otras tierras raras.In the context of the present invention, inorganic material is any mineral substance commonly used as a paper safety additive. Normally these minerals have some physical property that allows them to act as such security elements. Inorganic materials used as safety elements are normally capable of being excited at certain wavelengths while emitting luminescence to different lengths. The inorganic materials of the invention are minerals that comprise rare earths since these have the ability to excite in the visible spectral region and have a high level of emission intensity in the near-infrared spectral region. In a preferred embodiment, the inorganic materials of the invention have a perovskite-like structure such as strontium titanate doped with praseodymium or other rare earths. In another preferred embodiment the inorganic material has a garnet-like structure such as ytrium aluminate doped with erbium or other rare earths.
En Ia primera etapa del método se lleva a cabo Ia calcinación y aglomeración del material inorgánico sintetizado previamente. Este tratamiento térmico sirve para mejorar ciertos aspectos de los productos sintetizados como son su estabilidad química, grado de cristalinidad, su tamaño de cristalito y su estado de aglomeración. El tratamiento ha de ser diseñado en función del material y método de síntesis por el que haya sido sintetizado aunque de manera general Ia calcinación se llevará a cabo a una temperatura no superior a 16000C. En una realización preferida de Ia invención Ia calcinación se lleva a cabo entre 800 y 13000C.In the first stage of the method the calcination and agglomeration of the inorganic material previously synthesized is carried out. This heat treatment serves to improve certain aspects of the synthesized products such as their chemical stability, degree of crystallinity, their crystallite size and their state of agglomeration. The treatment must be designed according to the material and synthesis method by which it has been synthesized although in general the calcination will be carried out at a temperature not exceeding 1600 0 C. In a preferred embodiment of the invention the calcination will be carried out between 800 and 1300 0 C.
La segunda etapa del procedimiento conlleva someter al material aglomerado a una o varias etapas de molienda hasta un tamaño medio de partícula dentro del rango de 2 a 20 μm. Estos son tamaños compatibles con Ia preparación de papel. Por un lado las partículas no pueden ser superiores a 20 μm para que queden perfectamente integradas en el espesor de Ia lámina del papel final y para evitar su localización e identificación por tratarse de un elemento de seguridad. Por otro lado, si Ia concentración de partículas inferiores a 2 μm es muy alta Ia eficacia del producto será baja ya que durante el procedimiento de fabricación del papel se perderá gran parte del material con las aguas. Por tanto, los rangos de tamaños deben ser en unThe second stage of the process involves subjecting the agglomerated material to one or several grinding stages up to an average particle size within the range of 2 to 20 μm. These are sizes compatible with the paper preparation. On the one hand the particles cannot be greater than 20 μm so that they are perfectly integrated in the thickness of the sheet of the final paper and to avoid its location and identification because it is a security element. On the other hand, if the concentration of particles less than 2 μm is very high, the effectiveness of the product will be low since during the papermaking process, much of the material will be lost with the water. Therefore, the size ranges must be in a
100% menores de 20 μm y en un 95% mayores de 2 μm. Es decir, existe un rango de error del 5% pero solo para tamaños por debajo del límite inferior. No cabe error, sin embargo, en el límite superior ya que el acabado final del papel no sería satisfactorio por las razones expuestas anteriormente. En cualquier caso en una realización preferida de Ia invención el tamaño medio de las partículas debe estar comprendido dentro del rango de 3 a 7 μm.100% less than 20 μm and 95% greater than 2 μm. That is, there is a 5% error range but only for sizes below the lower limit. There is no mistake, however, in the upper limit since the final finishing of the paper would not be satisfactory for the reasons stated above. In any case, in a preferred embodiment of the invention, the average particle size must be within the range of 3 to 7 μm.
Tras el tratamiento térmico, los materiales se densifican, por Io que antes de Ia molienda fina hasta alcanzar el tamaño de partícula deseado es preciso comenzar con una molienda previa o quebrantado, que se puede realizar mediante técnicas como Ia quebrantadura de mandíbulas, de martillos o de rodillo. Este tipo de tratamientos se hacen por vía seca. En el caso de aglomerados blandos se pueden utilizar sistemas de agitación de alta cizalla, aprovechando esta etapa para Ia puesta en suspensión del material.After the heat treatment, the materials are densified, so that before the fine grinding until reaching the desired particle size, it is necessary to start with a previous or broken grinding, which can be carried out by techniques such as breaking the jaws, hammers or of roller. These types of treatments are done dry. In the case of soft agglomerates, high shear agitation systems can be used, taking advantage of this stage for the suspension of the material.
Debido a que Ia granulometría precisa para Ia pasta de papel debe ser fina como se mencionaba anteriormente, es preciso pasar por sistemas de molienda por vía húmeda ya que mediante vía seca se corre el riesgo de contaminar el material. Para Ia molienda por vía húmeda se pueden usar métodos como los molinos de bolas, sistemas de molienda por atrición o en el caso de que los aglomerados sean relativamente débiles, sistemas de dispersión de alta cizalla. Como es lógico, se pueden usar una combinación de todas las técnicas anteriormente mencionadas tanto en seco como húmedo para obtener Ia granulometría deseada.Because the precise granulometry for the paper pulp must be fine as mentioned above, it is necessary to pass through wet grinding systems since the risk of contaminating the material is run through a dry route. For wet milling, methods such as ball mills, attrition grinding systems or in the case that the agglomerates are relatively weak, high shear dispersion systems can be used. Naturally, a combination of all the above-mentioned techniques, both dry and wet, can be used to obtain the desired particle size.
El último paso del método comprende Ia suspensión del material con Ia granulometría adecuada en agua en presencia de uno o más agentes dispersantes. La cantidad de dispersante ha de ser determinada según Ia unidad de material activo a procesar. Como unidad de referencia debe usarse Ia superficie de material que es Ia que tiene sentido reológico. Por ello, Ia cantidad de agente dispersante necesario para Ia suspensión dependerá de Ia superficie específica del producto final. Son válidos para los fines de Ia presente invención tanto los dispersantes orgánicos como los inorgánicos. En cuanto al efecto dispersante predominante este puede ser de efecto estérico como en el caso del poliacrilato de amonio o iónico como en el caso del hexametafosfato sódico o mixto como por ejemplo en el caso del polietilenglicol. Tanto el poliacrilato de amonio, como el hexametafosfato sódico y el polietilenglicol representan los dispersantes preferidos de Ia invención aunque otros dispersantes también pueden resultar válidos. Los dispersantes pueden ser usados individualmente o mezclados entre si.The last step of the method comprises the suspension of the material with the appropriate particle size in water in the presence of one or more dispersing agents. The amount of dispersant must be determined according to the unit of active material to be processed. As a reference unit, the material surface that is the one that makes rheological sense should be used. Therefore, the amount of dispersing agent necessary for the suspension will depend on the specific surface area of the final product. Both organic and inorganic dispersants are valid for the purposes of the present invention. As for the predominant dispersing effect, this may be steric in the case of ammonium or ionic polyacrylate, as in the case of sodium or mixed hexametaphosphate, such as in the case of polyethylene glycol. Both ammonium polyacrylate, such as sodium hexametaphosphate and polyethylene glycol represent the preferred dispersants of the invention although other dispersants may also be valid. Dispersants can be used individually or mixed together.
El método de Ia invención puede incluir varias etapas opcionales dependiendo del tipo de material a procesar y del uso que se Ie pretenda dar a Ia solución acond ¡donadora final.The method of the invention may include several optional steps depending on the type of material to be processed and the use that is intended to be given to the final conditioning solution.
En el primer caso, cuando el material que ha de ser aglomerado no posee las dimensiones adecuadas para su calcinación puede ser sometido a alguna etapa de molienda previa. Esta molienda puede ser realizada por cualquiera de las técnicas mencionadas anteriormente.In the first case, when the material to be agglomerated does not have the appropriate dimensions for calcination, it can be subjected to some previous grinding stage. This grinding can be performed by any of the techniques mentioned above.
En el segundo caso, se puede dar Ia circunstancia de que el material acondicionado vaya a ser utilizado inmediatamente para Ia preparación del papel por Io que no existiría problema alguno. No obstante, si Ia aplicación del material se va a llevar a cabo con posterioridad y el material debe ser almacenado o va a ser transportado éste puede ser sometido a una etapa de secado para eliminar el agua. Esta etapa de secado se puede llevara a cabo mediante filtro de prensa o por atomización. Esta última técnica es preferible.In the second case, the circumstance can be given that the conditioned material will be used immediately for the preparation of the paper, so that there would be no problem. However, if the application of the material is to be carried out later and the material must be stored or transported, it can be subjected to a drying stage to remove the water. This drying stage can be carried out by means of a press filter or spray. This last technique is preferable.
Cuando el material vaya a ser incorporado a Ia pasta del papel, éste ha de ser resuspendido en agua. La presencia del dispersante en el material secado favorece el restablecimiento de Ia suspensión del material inorgánico de cara a su incorporación a Ia pasta de papel. Otro aspecto de Ia invención se refiere al material inorgánico acondicionado obtenible de acuerdo con el método de Ia invención.When the material is to be incorporated into the pulp of the paper, it must be resuspended in water. The presence of the dispersant in the dried material favors the restoration of the suspension of the inorganic material for its incorporation into the paper pulp. Another aspect of the invention relates to the conditioned inorganic material obtainable according to the method of the invention.
Es asimismo objeto de Ia invención un papel de seguridad que comprende un material inorgánico acondicionado obtenible de acuerdo con el método deThe object of the invention is also a security paper comprising an inorganic conditioned material obtainable according to the method of
Ia invención.The invention
Un último aspecto de Ia invención hace referencia al uso de un material inorgánico acondicionado de acuerdo con el método de Ia invención en Ia preparación de papel de seguridad.A final aspect of the invention refers to the use of a conditioned inorganic material according to the method of the invention in the preparation of security paper.
Los siguientes ejemplos sirven para ilustrar Ia presente invención aunque no pretenden tener un carácter limitativo de Ia misma.The following examples serve to illustrate the present invention although they are not intended to have a limiting character thereof.
Ejemplo 1Example 1
Para el caso de una sustancia activa luminiscente con estructura tipo Perovskita, se toma ésta, consistente en Titanato de Estroncio dopado con Praseodimio, preparada según se describe en el trabajo de H. Yamamoto, S. Okamoto y H. Kobayashi (Journal of Luminescence 100 (2002) 325-332).In the case of a luminescent active substance with a Perovskite-like structure, it is taken, consisting of Strontium titanate doped with Praseodymium, prepared as described in the work of H. Yamamoto, S. Okamoto and H. Kobayashi (Journal of Luminescence 100 (2002) 325-332).
Las cantidades adecuadas de SrCO3, TiO2 y PrCI3 se homogenizan en molino de bolas en seco y se introducen en un crisol de Cordierita-mullita de forma baja y de 2 litros de capacidad. Dicho crisol se introduce en un horno eléctrico capaz de alcanzar 15000C. Se calienta a una velocidad de 2°C/min hasta los 8000C para lograr Ia descomposición de las materias primas y posteriormente se sube Ia temperatura hasta los 13000C a una velocidad de 3°C/min. Se mantiene a Ia mencionada temperatura durante 120 min y se enfría a una velocidad de 3°C/min. A Ia temperatura de 200° se abre el horno para acelerar el enfriamiento. Tras esta etapa, el polvo aglomerado obtenido se somete a una molienda previa mediante una quebrantadora de mandíbulas hasta un tamaño menor de 0.5 mm.The appropriate quantities of SrCO 3 , TiO 2 and PrCI 3 are homogenized in a dry ball mill and placed in a Cordierita-mullita crucible of low form and of 2 liters capacity. Said crucible is introduced in an electric oven capable of reaching 1500 0 C. It is heated at a speed of 2 ° C / min to 800 0 C to achieve the decomposition of raw materials and subsequently the temperature is raised to 1300 0 C at a speed of 3 ° C / min. It is kept at said temperature for 120 min and cooled at a speed of 3 ° C / min. At 200 ° C the oven opens to accelerate cooling. After this stage, the obtained agglomerated powder is subjected to a previous grinding by means of a jaw crusher to a smaller size 0.5 mm
El polvo así obtenido se va a acabar de desaglomerar en un equipo de agitación de alta cizalla continuo, de Ia marca IKA. Para ello se prepara una mezcla consistente en un 49.9% en peso de agua desionizada, un 50% en peso de Ia sustancia a desaglomerar y un 0,1 % de hexametafosfato sódico. Dicha mezcla se procesará con el agitador de alta cizalla mediante el sistema de pasadas sucesivas para asegurarnos que todo el material pasa por Ia cámara de desaglomeración. Las pasadas continúan hasta que el tamaño de partícula de Ia suspensión, determinado mediante dispersión de radiación láser indica que el 100% de Ia población está por debajo de 20 micrómetros, y el tamaño medio entre 2 y 7 micrómetros, tamaños compatibles con Ia fabricación de papel.The powder thus obtained will be broken down into a continuous high shear agitation equipment, of the IKA brand. For this, a mixture consisting of 49.9% by weight of deionized water, 50% by weight of the substance to be deagglomerated and 0.1% of sodium hexametaphosphate is prepared. Said mixture will be processed with the high shear agitator through the system of successive passes to ensure that all the material passes through the deagglomeration chamber. The passes continue until the particle size of the suspension, determined by dispersion of laser radiation indicates that 100% of the population is below 20 micrometers, and the average size between 2 and 7 micrometers, sizes compatible with the manufacture of paper.
La suspensión así obtenida se puede añadir a Ia formulación de Ia pasta de papel correspondiente.The suspension thus obtained can be added to the formulation of the corresponding paper pulp.
En caso de querer transportarla, se procede a eliminar el agua, para Io cual se emplea un atomizador de rodete, empleando una presión de aire de 6 Kgr/cm2 para mover el rodete, una temperatura del aire de entrada de 35O0C.If you want to transport it, you proceed to remove the water, for which an impeller atomizer is used, using an air pressure of 6 Kgr / cm 2 to move the impeller, an inlet air temperature of 35O 0 C.
Para Ia posterior puesta en suspensión es suficiente emplear las mismas proporciones de polvo y agua (~ 50:50 % peso) y un agitador de alta velocidad.For subsequent suspension it is sufficient to use the same proportions of dust and water (~ 50:50% weight) and a high speed stirrer.
Ejemplo 2Example 2
Para el caso de una sustancia activa luminiscente con estructura de granate, se toma ésta, consistente en Aluminato de Ytrio dopado con Erbio, preparada según se describe en el trabajo de A. Leleckaite y A. Kareiva (Optical Materials 26 (2004) 123-128). Las cantidades adecuadas de Y2O3, Er2O3 y AI(NO3)3.9H2O se procesan según se describe a continuación. El oxido de Ytrio se disuelve en una solución 0.2 molar de ácido acético a 650C. A esta solución se añade el oxido de Erbio disuelto en ácido acético. A continuación se añade el Nitrato de Aluminio, previamente disuelto en agua. El conjunto se agita durante 3 horas a 650C. Posteriormente se añade 1 ,2-etanodiol como agente complejante. La solución se concentra mediante evaporación lenta a 650C hasta que se convierte en un gel transparente. El gel se tritura mecánicamente y se introduce en un crisol de Cordierita-mullita de forma baja y de 2 litros de capacidad. Dicho crisol se introduce en un horno eléctrico capaz de alcanzar 15000C. Se calienta a una velocidad de 2°C/min hasta los 8000C donde se mantiene 120 min para lograr Ia descomposición y reacción de las materias primas. El aglomerado así obtenido se somete a una molienda previa mediante una quebrantadora de mandíbulas hasta un tamaño menor de 0.5 mm. Posteriormente se vuelve a introducir en el crisol y en el horno, y se calienta hasta Ia temperatura de 10000C a una velocidad de 3°C/min. Se mantiene a Ia mencionada temperatura durante 120 min. Y se enfría a una velocidad de 3°C/min. A Ia temperatura de 200° se abre el horno para acelerar el enfriamiento.In the case of a luminescent active substance with a garnet structure, it is taken, consisting of Ytrium aluminate doped with Erbium, prepared as described in the work of A. Leleckaite and A. Kareiva (Optical Materials 26 (2004) 123- 128). Suitable amounts of Y 2 O 3 , Er 2 O 3 and AI (NO 3 ) 3 .9H 2 O are processed as described below. The Ytrium oxide is dissolved in a 0.2 molar solution of acetic acid at 65 0 C. To this solution is added Erbium oxide dissolved in acetic acid. Next, the Aluminum Nitrate, previously dissolved in water, is added. The whole is stirred for 3 hours at 65 0 C. Subsequently 1,2-ethanediol is added as a complexing agent. The solution is concentrated by slow evaporation at 65 0 C until it becomes a transparent gel. The gel is mechanically crushed and introduced into a Cordierita-mullita crucible of low shape and 2 liters capacity. Said crucible is introduced in an electric oven capable of reaching 1500 0 C. It is heated at a speed of 2 ° C / min to 800 0 C where 120 min is maintained to achieve the decomposition and reaction of the raw materials. The agglomerate thus obtained is subjected to a previous grinding by means of a jaw crusher up to a size smaller than 0.5 mm. Subsequently reintroduced into the pot and in the furnace and heated to the temperature of 1000 0 C at a rate of 3 ° C / min. It is maintained at said temperature for 120 min. And it cools at a speed of 3 ° C / min. At 200 ° C the oven opens to accelerate cooling.
Tras esta etapa, el polvo aglomerado obtenido se somete a una molienda previa mediante una quebrantadora de mandíbulas hasta un tamaño menor de 0,5 mm.After this stage, the obtained agglomerated powder is subjected to a previous grinding by means of a jaw crusher up to a size smaller than 0.5 mm.
El polvo así obtenido se va a acabar de desaglomerar en un equipo de agitación de alta cizalla continuo, de Ia marca IKA. Para ello se prepara una mezcla consistente en un 54,7% en peso de agua desionizada, un 45% en peso de Ia sustancia a desaglomerar y se añade un 0,3 % de poliacrilato de amonio (Dolapix CE64 Zschimmer & Schwarz GMBH & Co KG). Dicha mezcla se procesará con el agitador de alta cizalla mediante el sistema de pasadas sucesivas para asegurarnos que todo el material pasa por Ia cámara de desaglomeración. Las pasadas continúan hasta que el tamaño de partícula de Ia suspensión, determinado mediante dispersión de radiación láser indica que el 90% de Ia población está por debajo de 100 micrómetros. Posteriormente Ia suspensión se introduce en un molino de atrición con bolas de oxido de circonio de 3 mm y así se procesa hasta alcanzar un tamaño medio entre 3 y 7 micrómetros, tamaños compatibles con Ia fabricación de papel. La suspensión así obtenida se puede añadir a Ia formulación de Ia pasta de papel correspondiente.The powder thus obtained will be broken down into a continuous high shear agitation equipment, of the IKA brand. For this purpose, a mixture consisting of 54.7% by weight of deionized water, 45% by weight of the substance to be deagglomerated is prepared and 0.3% ammonium polyacrylate is added (Dolapix CE64 Zschimmer & Schwarz GMBH & Co KG) Said mixture will be processed with the high shear agitator through the system of successive passes to ensure that all the material passes through the breakdown chamber. The passes continue until the particle size of the suspension, determined by means of laser radiation dispersion, indicates that 90% of the population is below 100 micrometers. Subsequently, the suspension is introduced into an attrition mill with zirconium oxide balls of 3 mm and thus processed to reach an average size between 3 and 7 micrometers, sizes compatible with papermaking. The suspension thus obtained can be added to the formulation of the corresponding paper pulp.
En caso de querer transportarla se procede a eliminar el agua. Para secar Ia suspensión obtenida se emplea un atomizador de rodete, empleando una presión de aire de 6 Kgr/cm2 para mover el rodete, una temperatura del aire de entrada de 35O0C.In case of wanting to transport it, the water is eliminated. To dry the suspension obtained, an impeller atomizer is used, using an air pressure of 6 Kgr / cm 2 to move the impeller, an inlet air temperature of 35O 0 C.
Para Ia posterior puesta en suspensión es suficiente emplear las mismas proporciones de polvo y agua (~ 50:50 % peso) y un agitador de alta velocidad. For subsequent suspension it is sufficient to use the same proportions of dust and water (~ 50:50% weight) and a high speed stirrer.

Claims

REIVINDICACIONES
1. Método para el acondicionamiento de materiales inorgánicos aplicables como aditivos de seguridad en papel que comprende:1. Method for conditioning applicable inorganic materials as safety additives in paper comprising:
a) Calcinación y aglomeración del material inorgánico a una temperatura de hasta 1600° C,a) Calcination and agglomeration of inorganic material at a temperature of up to 1600 ° C,
b) Someter al material calcinado y aglomerado de a) a una o varias etapas de molienda hasta un tamaño medio de partícula de entre 2-20 μm,b) Subject the calcined and agglomerated material of a) to one or several grinding stages up to an average particle size between 2-20 μm,
c) Suspensión del material de b) en una solución acuosa con uno o más dispersantes,c) Suspension of the material of b) in an aqueous solution with one or more dispersants,
donde, opcionalmente, antes de Ia etapa a), puede llevarse a cabo otra etapa de molienda.where, optionally, before stage a), another grinding stage can be carried out.
2. Método según Ia reivindicación 1 caracterizado porque el material inorgánico tiene una estructura tipo perovskita.2. Method according to claim 1 characterized in that the inorganic material has a perovskite type structure.
3. Método según Ia reivindicación 2 caracterizado porque el material inorgánico con estructura tipo perovskita es el titanato de estroncio dopado con praseodimio u otras tierras raras.3. Method according to claim 2 characterized in that the inorganic material with perovskite type structure is strontium titanate doped with praseodymium or other rare earths.
4. Método según Ia reivindicación 1 caracterizado porque el material inorgánico tiene una estructura tipo granate.4. Method according to claim 1 characterized in that the inorganic material has a garnet type structure.
5. Método según Ia reivindicación 4 caracterizado porque el material inorgánico con estructura tipo granate es el aluminato de ytrio dopado con erbio u otras tierras raras. 5. Method according to claim 4 characterized in that the inorganic material with garnet type structure is ytrium aluminate doped with erbium or other rare earths.
6. Método según Ia reivindicación 1 caracterizado porque Ia calcinación y aglomeración del material inorgánico se lleva a cabo a una temperatura de entre 800-13000C.6. Method according to claim 1 characterized in that the calcination and agglomeration of the inorganic material is carried out at a temperature of between 800-1300 0 C.
7. Método según Ia reivindicación 1 caracterizado porque Ia molienda se lleva a cabo mediante quebrantadura de mandíbulas, martillos o de rodillo; agitación de alta cizalla; molinos de bolas; molienda por atrición, dispersión de alta cizalla; o una combinación de las mismas.7. Method according to claim 1 characterized in that the grinding is carried out by breaking jaws, hammers or rollers; high shear agitation; ball mills; attrition grinding, high shear dispersion; or a combination thereof.
8. Método según Ia reivindicación 1 caracterizado porque Ia molienda se puede llevar a cabo por vía seca o húmeda.8. Method according to claim 1 characterized in that the grinding can be carried out by dry or wet.
9. Método según Ia reivindicación 1 caracterizado porque el tamaño medio de partícula obtenido en Ia etapa b) está entre 3-7 μm.9. Method according to claim 1 characterized in that the average particle size obtained in step b) is between 3-7 μm.
10. Método según Ia reivindicación 1 caracterizado porque el dispersante es el hexametafosfato sódico, polietilenglicol de bajo peso molecular o poliacrilato de amonio o alguna de sus mezclas.10. Method according to claim 1 characterized in that the dispersant is sodium hexametaphosphate, low molecular weight polyethylene glycol or ammonium polyacrylate or any of its mixtures.
11. Método según Ia reivindicación 1 que opcionalmente puede incluir una etapa de secado para el almacenamiento del material inorgánico o para su transporte.11. Method according to claim 1, which may optionally include a drying step for the storage of the inorganic material or for its transport.
12. Método según Ia reivindicación 11 caracterizado porque el secado se lleva a cabo mediante filtro de prensa o por atomización.12. Method according to claim 11 characterized in that the drying is carried out by means of a press filter or by atomization.
13. Material inorgánico acondicionado para su incorporación en papel obtenible mediante el método de cualquiera de las reivindicaciones 1-12.13. Inorganic material conditioned for incorporation into paper obtainable by the method of any of claims 1-12.
14. Papel de seguridad que comprende en su composición un material inorgánico acondicionado según Ia reivindicación 13. 14. Security paper comprising in its composition a conditioned inorganic material according to claim 13.
15. Uso de un material inorgánico acondicionado según Ia reivindicación 12 en Ia preparación de papel de seguridad. 15. Use of a conditioned inorganic material according to claim 12 in the preparation of security paper.
PCT/ES2008/000602 2007-10-04 2008-09-24 Method for conditioning mineral materials such as safety additives WO2009043948A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6200628B1 (en) * 1997-12-29 2001-03-13 Sicpa Holding S.A. Use of inorganic particles and method for making and identifying a substrate or an article
US6344261B1 (en) * 1998-02-02 2002-02-05 Giesecke & Devrient Gmbh Printed document having a value and comprising a luminescent authenticity feature based on a host lattice

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6200628B1 (en) * 1997-12-29 2001-03-13 Sicpa Holding S.A. Use of inorganic particles and method for making and identifying a substrate or an article
US6344261B1 (en) * 1998-02-02 2002-02-05 Giesecke & Devrient Gmbh Printed document having a value and comprising a luminescent authenticity feature based on a host lattice

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