Nucleic acid analogs provide a particularly useful tool for the preparation of complex polymeric structures of defined geometry because they are relatively stable to reaction conditions for the preparation of such structures and provide the opportunity to induce reactive groups which would not be possible with usual nucleic acids.

Subject of the present invention is a method for constructing a 2- or 3-dimensional defined polymeric geometric structure from oligomeric elements, such geometric structures as well as the use of nucleic acid analogues in assembling of supramolecular structures of defined form.
Living organisms are build from biomolecules particularly by defined self association of such biomolecules (lipids, protein complexes and DNA double helix). Such supramolecular structures occurring in living organisms are relatively unstable outside of these organisms, because the biomolecules have only limited affinity and are biologically degradable.
Lehn (Science 260, 1762-1763, 1993) describes the use of artificial self assembled complexes from low molecular weight organic molecules and metal ions.
It is further known that holes can be created in Longmuir-Blodget-layers during cluster formation. Such artificial systems are based on the association of uniform molecules having no or small differences.
In nature complex structures are made up from macro molecules of different tertiary structures, based upon uniform basic structures like amino acids and nucleotides. Nucleic acids of complementary sequence form helical chains which can form later in-vivo special structures and networks.
In Angew. Chem. Int. Ed. Engl. 1997, 36, 7, 735-739 a supramolecular structure based on macrocycles is disclosed. In J. Am. Chem. Soc. 1997, 119, 852-853, control of stereochemistry in supramolecular architecture is described.
In J. Vac. Sci. Technol. A 12(4), 1895-1903, there is described the self-assembly of DNA molecules to form a 2-dimensional latice. Such latices are formed using DNA molecules the nucleotide sequence of which is chosen such that four or more of such DNA molecules have a preferred assembly to form a junction. There is explicit explanation in this document how the sequences of the DNA molecules involved has to be chosen. Further there is at least theoretical disclosure how a 3-dimensional object, like a cube, can be created from 6 cyclic DNA molecules. Again, the sequences of the DNA molecules are chosen such that the structure is stabilized and defined by the formation of double stranded DNA along the edges of the cube.
In DE-A-3924454 and U.S. Pat. No. 5,561,071 there is described the use of self-assembled double stranded DNAs for forming conducting elements, for example elements used in electronic chips. The disclosure of this reference is incorporated by reference into the present specification.
The supramolecular structures prepared by self-assembly of DNA have now been found to be so unstable under in vitro conditions that, for example electronic chips prepared by them are not reliable.
In WO 92/20702 there are disclosed purely synthetic oligomeric molecules which are capable of binding to complementary nucleic acids with very high affinity. This can be used for either therapy within the human body or in the diagnosis of nucleic acids in vivo or in vitro. Peptide nucleic acids (PNAs) as described in this reference are characterized by having a non-naturally occurring backbone having attached nucleobases at defined positions, such that these nucleobases can hydrogen bond to the complementary bases on a DNA strand, thus forming a double or triple stranded complex.
It was therefore an object of the present invention to provide high molecular weight supramolecular structures in a more reliable way.
It was an alternative or additional object of the present invention to provide more stable high molecular weight supramolecular structures in a predictable way.
In a further object of the present invention to provide new materials based on supramolecular structures in an intended way, which can be used in computer chips, in roboting, such as robot arms in nanometer scale, in new materials/polymers with conductivity and/or insulator properties.
Subject of the present invention is therefore a method for constructing a 2- or 3-dimensional defined polymeric geometric structures comprising the steps of combining a first oligomeric element having bound recognition elements with a second oligomeric element having bound recognition elements capable of recognizing the recognition elements of said first oligomeric element at binding conditions, wherein said recognition elements are heterocyclic moieties recognizing other recognition elements via hydrogen bonding and wherein said recognition elements of said first and second oligomeric element are bound to spaced defined locations of a peptide bond containing backbone. A further subject of the present invention are such polymeric geometric structures.
FIG. 1 shows the structure of a self-assembled 2-dimensional geometric structure prepared by self-assembly of three different peptide nucleic acids.
A defined geometric structure according to the present invention is a structure having a defined expansion and which can be drawn schematically. Examples of such defined geometric structures are latices, junctions, cubes and branched molecules as described in the above mentioned prior art. Therefore, the invention can be used in nano-engineering to create intended structures. While the prior art describes DNA for making up the structure, the present invention is directed to the use of oligomeric elements comprising a peptide like bond containing backbone. The geometric structures preferably contain at least one branching point. A branching point is defined to be the location where three or more arms meet. At least one of these arms comprises a segment wherein one strand of this arm is bound to a strand of a further oligomeric element. The oligo- or polymeric geometric structure according to the present invention comprise at least two oligomeric elements. However, it is preferred that such a structure contains 6 or more, preferably between 8 and 1 Million oligomeric elements. In this definition oligomeric structures will contain from 2 to 20 and polymeric structures more than 21 oligomeric elements. These oligomeric elements can be of the same kind, for example only differing in the sequence of the recognition elements, preferably, however, the oligomeric elements are of a different kind, for example differing in sequence and in molecular structure, for example some of them being modified further or being based on different backbones or moieties attached.
An oligomeric element according to the invention is defined to contain affinity moieties, such as alkyl, aryl, aromatic or/and heterocyclic moieties recognizing other heterocyclic molecules via van-der-Waals interaction, xcfx80-stacking, water exclusion or hydrogen bonding. Said affinity moieties are bound to spaced defined locations of a polyamide backbone. The backbone is generally a non-naturally occurrin backbone. The backbone preferably contains repetitive monomeric subunits, such subunits being covalently bound together, preferably using amide bond formation. While it is much preferred to use only one kind of monomeric subunit in the backbone, it is possible to use different subunits and/or different bonds within the backbone either mixed individually or as stretches containing several identical subunits, as described in WO 95/14706, EP 700928, EP 646595 and EP 672677.
Oligomeric elements having both a non-natural backbone part as well as an excessable oligonucleotide and can be used to postmodify the geometric structure after assembly. Thus, it is possible to attach further mononucleotide units to the end of the oligomeric unit, for example as described in EP 720615.
Preferred oligomeric elements, such as peptide nucleic acids (PNAs), are described in WO 92/20702. Such compounds comprise a containing polyamide backbone bearing a plurality of heterocyclic moieties that are individually bound to amine atoms located within said backbone.
Preferred peptide nucleic acids are shown in formula I:
wherein
n is an integer of from at least 3,
x is an integer of from 2 to nxe2x88x921,
each of L1-Ln is a ligand independently selected from the group consisting of hydrogen, hydroxy, (C1-C4)alkanoyl, naturally occurring nucleobases, non-naturally occurring nucleobases, aromatic moieties, DNA intercalators, nucleobase-binding groups, heterocyclic moieties, reporter ligands and chelating moieties, at least one of L1-Ln containing a primary or secondary amino group;
each of C1-Cn is (CR6R7)y (preferably CR6R7, CHR6CHR7 or CR6R7CH2) where R6 is hydrogen and R7 is selected from the group consisting of the side chains of naturally occurring alpha amino acids, or R6 and R7 are independently selected from the group consisting of hydrogen, (C1-C6)alkyl, aryl, aralkyl, heteroaryl, hydroxy, (C1-C6)alkoxy, (C1-C6)alkylthio, NR3R4 and SR5, where R3 and R4 are as defined below, and R5 is hydrogen, (C1-C6)alkyl, hydroxy, (C1-C6)alkoxy, or (C1-C6)alkylthio-substituted (C1-C6)alkyl or R6 and R7 taken together complete an alicyclic or heterocyclic system; or C1-Cxe2x80x3 is CO, CS, CNR3;
each of D1-Dn is (CR6R7)z (preferably CR6R7, CHR6CHR7 or CH2CR6R7) where R6 and R7 are as defined above;
each of y and z is zero or an integer from 1 to 10, the sum y+z being at least 2, preferably greater than 2, but not more than 10;
each of G1-Gnxe2x88x921 is xe2x80x94NR3COxe2x80x94, xe2x80x94NR3CSxe2x80x94, xe2x80x94NR3SOxe2x80x94or xe2x80x94NR3SO2xe2x80x94, in either orientation, where R3 is as defined below;
each of A1-An and B1-Bn are selected such that:
(a) A1-An is a group of formula (I/A), (I/B), (I/C) or (I/D), and B1-Bn is N or R3N+; or
(b) A1-An is a group of formula (I/D) and B1-Bn is CH;
xe2x80x83wherein:
X is O, S, Se, NR3, CH2 or C(CH3)2;
Y is a single bond, O, S or NR4;
each of p and q is zero or an integer from 1 to 5, (the sum p+q being preferably not more than 5);
each of r and s is zero or an integer from 1 to 5, (the sum r+s being preferably not more than 5);
each R1 and R2 is independently selected from the group consisting of hydrogen, (C1-C4)alkyl which may be hydroxy- or (C1-C4)alkoxy- or (C1-C4)alkylthio-substituted, hydroxy, (C1-C4)alkoxy, (C1-C4)alkylthio, amino and halogen; and
each R3 and R4 is independently selected from the group consisting of hydrogen, (C1-C4)alkyl, hydroxy- or alkoxy- or alkylthio-substituted (C1-C4)alkyl, hydroxy, (C1-C6)-alkoxy, (C1-C6)-alkylthio and amino;
Q and I are independently selected from the group consisting of NH2, CONH2, COOH, hydrogen, (C1-C6)-alkyl, Oxe2x80x94(C1-C6)-alkyl, amino protected by a amino protecting groups, reporter ligands, intercalators, chelators, peptides, proteins, carbohydrates, lipids, steroids, nucleosides, nucleotides, nucleotide diphosphates, nucleotide triphosphates, oligonucleotides, including both oligoribonucleotides and oligodeoxyribonucleotides, oligonucleosides and soluble and non-soluble polymers as well as nucleic acid binding moieties and
each of x1 and y1 is an integer of from 0 to 10.
Most preferred nucleic acid binding compounds comprise at least one monomeric subunit of the general formula II:
wherein
L is a ligand as defined above for L1-Ln,
k, l and m is independently zero or an integer from 1 to 5,
p is zero or 1, and
R7 is selected from the group consisting of hydrogen and the side chains of naturally occurring alpha amino acids.
Preferred recognition elements are nucleobases, like naturally occurring nucleobases, like A, G, C, T and U, rare bases, like inosine, 5-methylcytosine or thiouracil, as well as any non-naturally occurring analogues, like 7-deaza-dGTP, bromothymine and azaadenines. These recognition elements are able to recognize corresponding recognition elements on another oligomeric element, as known in the art. The present invention thus provides the possibility to create intended structures, with high specificity, for example based on sequences of recognition elements.
Hydrogen bonding is a way of binding, particularly as occurring between two strands of a nucleic acid, including Watson-Crick base pairing and Hoogsteen base pairing.
The recognition elements are bound to specified and constant locations on the backbone, preferably separated by between 4 and 8 intervening atoms. The preferred atom of attachment is a nitrogen atom.
The oligomeric elements used in the present invention can be prepared by methods as described in the above documents. The use of peptide like bonds within the backbone provides a good opportunity of easy synthesis using DNA or peptide synthesizers. When prepared, the oligomeric elements can be coupled to other moieties that are intended to be included in the geometric structure of the present invention, such as recognizing moieties, moieties that can be recognized, catalytically active moieties, labels or chemically reactive or activatable moieties. Recognizing moieties and moieties that can be recognized are moieties that can recognize and preferably bind to an other component. Examples are immunologically reactive compounds, antibodies, antigens, and preferably peptide epitomes containing moieties, like polyhaptens or cyclic peptides. Such moieties can also connect oligomeric elements, for example can one end of a cyclic peptide be linked to a first oligomeric element and the other end be linked to a second oligomeric element. This can be accomplished by synthesizing such conjugate before introducing into the polymeric structure, for example in a peptide synthesizer.
Catalytically active moieties are enzymes, preferably polymeric enzymes, for example aggregates of a large numbers of enzymes, bound together covalently. A variety of labels can be conjugated to the oligomeric element, for example fluorescence labels, dyes, or even metals or other solid particles. Preferred are reactive groups.
Reactive groups useful in the present invention are groups that can bind covalently to other groups, like recognizing moieties as defined above, preferably, groups that can be used to crosslink oligomeric elements or to bind any further moieties to the oligomeric elements before or after assembly of the polymeric structure. Such crosslinking moieties are for example arylazide, acylazide, diazirines, ketones, quinones, and psoralens. The preparation of oligomeric elements useful in the present invention is disclosed in detail in WO 92/20702 and U.S. Pat. No. 5,539,082. These references are incorporated herein.
As mentioned above the use of chimeric elements offers the possibility to extend shorter oligomeric elements by, for example, enzymatic extension reactions using mononucleotides. Another example of extension is chemical ligation of oligomeric subunits by reaction of a thioester on one oligomer with a thiol group on another oligomer, also containing an amino group close to the thiol group. The thioester exchange will link the two oligomers together. Then the amino group on the second oligomer will interchange the newly formed thioester to form an amide bond (Canne et al. J. Am. Chem. Soc. 1996, 118, 5891-5896). Another example of chemical ligation is the combination of an activated group of one oligomer subunit with a functional group on the same or another oligomeric subunit. This reaction can be performed by an activated carboxylic acid derivative on one oligomer and an amino group on the same or on an other oligomer.
Covalent joining of two segments can also be performed by using duplexes/triplexes having overhanging ends. The overhanging end of one duplex can then hybridize with the overhanging end of the other duplex/triplex, thus forming a duplex with double length. By employing a recognition moiety capable of making a crosslink (see above) the overhanging region can be covalently joined.
In a preferred mode of the method of the present invention at least two oligomeric elements are combined under conditions suitable for binding the oligomeric elements together by hydrogen bonding via the recognition elements. Suitable conditions for peptide nucleic acid are disclosed in WO 92/20703. One of the biggest advantages of the use of PNA in the present invention is that they can bind via base pairing to nucleic acids or other PNA oligomers in non-physiological media, for example in water without or with very low salt content.
PNA having bound chelating moieties are disclosed in WO 95/14708. These PNA oligomers further give the opportunity to bind metal ions (thus doping the geometrical structure with metal ions) for increasing electric conductivity within such oligo/polymeric structure. PNA having attached peptide moieties are disclosed in WO 95/16202. These compounds provide the opportunity to functionalize the geometric structure according to the present invention by post modification, for example enzymatic modification, or to build up new or additional association structures, like the use of antibodies to bind to peptide antigens by making a xe2x80x9cbridgexe2x80x9d structure.
Contrary to the recognition between nucleic acids, the distances of affinity moieties in the sequence can be chosen more freely, because it is not necessary that, especially in the case wherein the first and second oligomeric element are made up of the same kind of backbone, to recognize nucleic acids, as in methods for nucleic acids determination. Therefore, the present invention provides a much more flexible way of constructing geometric structures than structures prepared by using naturally occurring DNA. However, it may be preferred, that the distances between recognition elements within the segments of each oligomeric element are at least compatible or similar, and preferably within segments of oligomeric elements designed for binding together via hydrogen bonding, and the distances between said recognition elements are such that xcfx80-stacking and/or water exclusion of the recognition elements is still possible. Favorable interstrand interaction can be readily determined by determining the melting temperatures (Tm) of the double/triple stranded product produced by the first and second oligomeric element. The higher the Tm, the higher the interstrand affinity.
A 1-dimensional structure is a structure having no branching points, i.e. a linear structure.
A 2-dimensional structure according to the present invention is for example a structure having linear structures oriented in one layer, wherein said linear structures are preferentially connected to each other at branching points. A 2-dimentional structure can be straight, curved or ring formed. Rings may be linked together as in a chain or catenants.
A 3-dimensional structure can be defined as a 2-dimensional structures extended into more than one layer or containing more than one branching point. An example of 3-dimensional structure is a cube, a tube, or spiral shaped structure.
The geometric structures constructed according to the present invention are of high interest in the preparation of nano-structures and nano-engineering. The development of nano-structures is of interest because of the small space required for advanced instruments and the requirements of small amounts of material compared to macroscopic structures. The development into nano-structures can best be explained in the field of computers. While the first computers required large space because the underlying hardware had extended dimensions, development of semiconductor technology made it possible to create computers having very high capacity but requiring only limited space. It is now recognized that the presently used photolithographic modes for preparing computer chips limits the further downscaling of chips. Nano-structures as produced in the present invention now provide for these smaller dimensions necessary for the construction of even downscaled computer chips.
This possibility now enables the construction of wires or conducting elements as small, preferably in diameter, as double stranded nucleic acid analogues, the dimensions of which are in about the same range as double stranded nucleic acids. However, by including single stranded segments into the geometric structure, it is possible to even downscale any wires to the strength of single stranded nucleic acid analogues or even simple organic molecules, for example carbohydrids.
The geometric structures according to the present invention can be prepared by combining two or more oligomeric elements (either extended or not extended), under conditions wherein they can bind in a specific or non-specific way using the recognition elements. When specific joining is intended, then natural or non-natural nucleobases can be used which are capable of base pairing (a process generally called hybridization). When non-specific joining is intended, then duplex formation takes place preferentially by interstrand xcfx80-stacking and/or water exclusion.
In a first application of the geometric structure of the present invention the structure is therefore used as a mask to create a defined pattern, for example on a surface. Fixating of the nucleic acid analogue may be by passive adsorption to the surface but can also be performed by bond formation (ionic or covalently) between the analogue and the surface. Such bond can be formed by thermal or photochemical means.
The pattern created on the surface can be used to cover or coat part of or all remaining parts (for example on said surface), not covered by said structure by a material, for example with doped silicon, for example using metallo organic chemical vapour deposition, removing the geometric structure containing the assembled oligomeric elements, and then applying to the now unprotected part of the surface a second material, for example a conductor as doped gallium arsenide or doped silicon. Therefore the geometric structure of the present invention can be designed as a network or a lattice, thus enabling the defined production of chips. A part of said conceptual considerations for preparation of computer chips from networks or latices can be transferred in analogy from U.S. Pat. No. 5,561,071 which to this end is incorporated herein by reference.
The use of nucleic acid analogues and especially peptide nucleic acids in this field has considerable advantages. Nucleic acid analogues are more stable than nucleic acids under the conditions of coating surfaces with metals. Especially in the field of the preparation of computer chips where one break within the geometric structure, for example by breaking a glycosidic or phosphate bond in one of the nucleic acids, would have the severe consequence on the electric current that then could not flow through the xe2x80x9cwirexe2x80x9d.
PNA are nucleic acid analogues that in preferred embodiments do not contain glycosidic or/and phosphate bonds, and as such is much more stable, which reduces the risk of strand breaks considerably compared to nucleic acids. This makes the chips prepared using nucleic acid analogues far more reliable in use. In addition nucleic acid analogues, as PNA, can be modified as described above in a more flexible way, due to their relatively flexible way for introducing chemically reactive sites.
In a second embodiment, the supramolecular geometric structures prepared according to the present invention can be used as scaffolds for electron transfer and thus lead electric current themselves. It was now determined that double strands constructed using oligomeric elements of the present invention, particularly if an uninterrupted xcfx80-stack of heterocyclic moieties or other aromatic/conjugated systems is contained within the double strand, can act as a nano-structural conductor for electrons (see for example U.S. Pat. No. 5,591,578 or C and EN, Feb. 24, 1997, Angew. Chem. Int. Ed. Engl. 1997, 36, 7, 735-739 or J. Am. Chem. Soc. 1997, 119, 852-853). In a simple application, it is thereby possible to connect two macroscopic electrodes via an electron transfer scaffold, xe2x80x9cwirexe2x80x9d, composed of a double strand of oligomeric elements. Such electrodes can be metallic surfaces, to which one of the oligomeric elements of the geometric structure is attached directly, for example covalently, or indirectly, for example by absorbing the geometrical structure or an oligomeric element to the electrode surface. Immobilization of PNA to a carbon electrode is described in J. Am. Chem. Soc. 1996, 118, 7667-7670. The content of this publication is incorporated by reference as it is directed to the preparation of a nucleic acid analogue attached to an electrode and the measurement of potentiograms of double stranded nucleic analogues bound to the electrode.
Using the present invention, it is possible to connect two electrodes, each of them being prepared according to the prior art, by assembling a geometric structure according to the invention. This can be made in a linear way, as described above, or can include more partial surfaces, for example separated electrodes, which can be connected in a directed way using specific sets of oligomeric elements. For example it is possible to provide a surface with an array of electrodes, each electrode having attached a specific oligomeric element or even an extended polymeric structure and thereafter connecting selected electrodes by connecting the oligomeric elements to create a geometric structure according to the invention or arms of an extended geometric structure of one electrode with an oligomeric element or an extended geometric structure of another selected electrode. In this way, customer-designed electrodes and structures can be prepared. Such devices containing an array of electrodes can be produced by selectively applying one or more small droplets of a solution containing these structures or oligomeric elements to the surface of each electrode. Any excess of compounds may be washed away. Thereafter the connections between the selected electrodes can be established as described above.
It is further possible to postmodify any geometrical structure produced according to the method of the present invention by crosslinking or even enzymatic extension. Crosslinking can be effected by irradiating a geometric structure having incorporated a photochemically active moiety, like acridine, arylazide, acylazide, diaziridines, ketones, quinones or psoralenes with light of an appropriate wavelength for activating the crosslinking reaction. Crosslinking can also be made by thermochemical means, like in polymer preparation by radical or electrophilic chain reactions using double bond containing moieties, like acrylates or styrenes, or by activation of functional groups like carboxylic acids which, when activated, are capable to react with other functional groups like amines. In this way additional branching points or even interstrand/duplex stabilization of double stranded parts can be accomplished. It is further possible to dope any negatively charged moieties in the geometrical structure by ions, for example silver ions, analogously to the method disclosed in Nature, vol. 391, p. 775, 1998, to which reference is made for the preparation and use of such doped structure.
Three dimensional structures can be made in a consecutive manner by adding 2-dimensional structures on top of each other, which forms an integrated multilayer structure forms structure.
Modification of the conformation of a 3-dimensional structure can be done by using special photochemical groups, like azabenzenes, stilbene, which isomerise (e.g. cis/trans isomers) upon irradiation.
The 2- or 3-dimensional structures can be preformed in solution before addition to e.g. a solid phase or made directly on the surface by first adding one strand of a duplex to the surface and then adding the complement strand so the duplex is formed on the solid surface. The precipitated structure may retain its structure as in solution, e.g. tertiary form as a helix, or it may change structure on the surface from a helix to a duplex with the form as a ladder.
Furthermore another advantage of using PNA is that the molecules allow for certain sequences to form stable triplexes (PNA-DNA-PNA, or PNA-PNA-PNA). This binding motif allows to prepare much more integrated structures than e.g. DNA.
Further subject of the present invention therefore is the use of compounds containing or being prepared by using a monomeric subunit of the general formula
wherein
X is an amino protecting group and Y is a carboxyl protecting group,
R7 is a moiety containing a functional group with a positive or negative charge, for example a carboxyl group, phosphate group or ammonium group, or is a moiety capable of complexing or chelating metal ions, or is a reactive group, for example for inducing covalent crosslinking, for example mercapto, maleinimido, quinone, nitrene or carbene or as described above and L is an affinity moiety preferably heterocyclic moiety or a reactive aromatic moiety, for example an aromatic azide or quinone for the preparation of supramolecular structures of defined form on the basis of base sequence specificity or base non-specificity, particularly for the construction of new materials (e.g. new polymers), capable of base pairing to nucleobases, conducting networks and computer chips, and for crosslinking such structures, or binding recognizing moieties to such structures.
Nucleic acid analogues provide a particularly useful tool for the preparation of complex polymeric structures of defined geometry because they are relatively stable to reaction conditions for the preparation of such structures and provide the opportunity to introduce reactive groups which would not be possible with usual nucleic acids.
A further advantage of the use of nucleic acid analogues is the possibility to provide them with better solubility in organic solvents and their relatively lower solubility in water compared to nucleic acids. Furthermore, the lipophilic nature of the nucleic acid analogues provides much higher affinities for many surfaces.

2- or 3-dimensional geometric structures


Provided is a fiberglass binder composition which comprises a polycarboxy polymer, polyol and an imidazoline. The binder also preferably includes a catalyst which is an alkali metal salt of a phosphorus-containing organic acid. The resultant binder provides minimal processing difficulties and a product which exhibits minimal water absorption.

1. Field of The Invention
The subject invention pertains to polycarboxy polymer binding resins having improved water absorption properties. More particularly, the subject invention pertains to thermosetting, acrylic acid-based binder resins which cure by crosslinking with a poly-functional, carboxyl group-reactive curing agent, which binders containing such resins exhibit minimal water absorption. Such binders are useful as replacements for formaldehyde-based binders in non-woven fiberglass goods.
2. Description of The Related Art
Fiberglass binders have a variety of uses ranging from stiffening applications where the binder is applied to woven or non-woven fiberglass sheet goods and cured, producing a stiffer product; thermo-forming applications wherein the binder resin is applied to sheet or lofty fibrous product following which it is dried and optionally B-staged to form an intermediate but yet curable product; and to fully cured systems such as building insulation.
Fibrous glass insulation products generally comprise matted glass fibers bonded together by a cured thermoset polymeric material. Molten streams of glass are drawn into fibers of random lengths and blown into a forming chamber where they are randomly deposited as a mat onto a traveling conveyor. The fibers, while in transit in the forming chamber and while still hot from the drawing operation, are sprayed with an aqueous binder. A phenol-formaldehyde binder has been used throughout the fibrous glass insulation industry. The residual heat from the glass fibers and the flow of air through the fibrous mat during the forming operation are generally sufficient to volatilize the majority of the water from the binder, thereby leaving the remaining components of the binder on the fibers as a viscous or semi-viscous high solids liquid. The coated fibrous mat is transferred to a curing oven where heated air, for example, is blown through the mat to cure the binder and rigidly bond the glass fibers together.
Fiberglass binders used in the present sense should not be confused with matrix resins which are an entirely different and non-analogous field of art. While sometimes termed xe2x80x9cbindersxe2x80x9d, matrix resins act to fill the entire interstitial space between fibers, resulting in a dense, fiber reinforced product where the matrix must translate the fiber strength properties to the composite, whereas xe2x80x9cbinder resinsxe2x80x9d as used herein are not space-filling, but rather coat only the fibers, and particularly the junctions of fibers. Fiberglass binders also cannot be equated with paper or wood product xe2x80x9cbindersxe2x80x9d where the adhesive properties are tailored to the chemical nature of the cellulosic substrates. Many such resins, e.g. urea/formaldehyde and resorcinol/formaldehyde resins, are not suitable for use as fiberglass binders. One skilled in the art of fiberglass binders would not look to cellulosic binders to solve any of the known problems associated with fiberglass binders.
Binders useful in fiberglass insulation products generally require a low viscosity in the uncured state, yet characteristics sufficient to form a rigid thermoset polymeric mat for the glass fibers when cured. A low binder viscosity in the uncured state is required to allow the mat to be sized correctly. Also, viscous binders tend to be tacky or sticky and hence they lead to accumulation of fiber on the forming chamber walls. This accumulated fiber may later fall onto the mat causing dense areas and product problems. A binder which forms a rigid solid when cured is required so that a finished fiberglass thermal insulation product, when compressed for packaging and shipping, will recover to its as-made vertical dimension when installed in a building.
From among the many thermosetting polymers, numerous candidates for suitable thermosetting fiber-glass binder resins exist. However, binder-coated fiberglass products are often of the commodity type, and thus cost becomes a driving factor, generally ruling out such resins as thermosetting polyurethanes, epoxies, and others. Due to their excellent cost/performance ratio, the resins of choice in the past have been phenol/formaldehyde resins. Phenol/formaldehyde resins can be economically produced, and can be extended with urea prior to use as a binder in many applications. Such urea-extended phenol/formaldehyde binders have been the mainstay of the fiberglass insulation industry for years, for example.
Over the past several decades however, minimization of volatile organic compound emissions (VOCs) both on the part of the industry desiring to provide a cleaner environment, as well as by Federal regulation, has led to extensive investigations into not only reducing emissions from the current formaldehyde-based binders, but also into candidate replacement binders. For example, subtle changes in the ratios of phenol to formaldehyde in the preparation of the basic phenol/formaldehyde resole resins, changes in catalysts, and addition of different and multiple formaldehyde scavengers, has resulted in considerable improvement in emissions from phenol/formaldehyde binders as compared with the binders previously used. However, with increasingly stringent Federal regulations, more and more attention has been paid to alternative binder systems which are free from formaldehyde.
One such candidate binder system employs polymers of acrylic acid as a first component, and a polyol such as glycerin or a modestly oxyalkylated glycerin as a curing or xe2x80x9ccrosslinkingxe2x80x9d component. The preparation and properties of such poly(acrylic acid)-based binders, including information relative to the VOC emissions, and a comparison of binder properties versus urea formaldehyde binders is presented in xe2x80x9cFormaldehyde-Free Crosslinking Binders For Non-Wovensxe2x80x9d, Charles T. Arkins et al., TAPPI JOURNAL, Vol. 78, No. 11, pages 161-168, November 1995. The binders disclosed by the Arkins article, appear to be B-stageable as well as being able to provide physical properties similar to those of urea/formaldehyde resins.
U.S. Pat. No. 5,340,868 discloses fiberglass insulation products cured with a combination of a polycarboxy polymer, a-hydroxyalkylamide, and an at least one trifunctional monomeric carboxylic acid such as citric acid. The specific polycarboxy polymers disclosed are poly(acrylic acid) polymers. See also, U.S. Pat. No. 5,143,582
U.S. Pat. No. 5,318,990 discloses a fibrous glass binder which comprises a polycarboxy polymer, a monomeric trihydric alcohol and a catalyst comprising an alkali metal salt of a phosphorous-containing organic acid.
Published European Patent Application EP 0 583 086 A1 appears to provide details of polyacrylic acid binders whose cure is catalyzed by a phosphorus-containing catalyst system as discussed in the Arkins article previously cited. Higher molecular weight poly(acrylic acids) are stated to provide polymers exhibiting more complete cure. See also U.S. Pat. Nos. 5,661,213; 5,427,587; 6,136,916; and 6,221,973.
Some polycarboxy polymers have been found useful for making fiberglass insulation products. Problems of clumping or sticking of the glass fibers to the inside of the forming chambers during the processing, as well as providing a final product that exhibits the recovery and rigidity necessary to provide a commercially acceptable fiberglass insulation product, have been overcome. See, for example, U.S. Pat. No. 6,331,350. The thermosetting acrylic resins have been found to be more hydrophilic than the traditional phenolic binders, however. This hydrophilicity results in fiberglass insulation that is more prone to absorb liquid water, thereby possibly compromising the integrity of the product. Also, the thermosetting acrylic resins now being used as binding agents for fiberglass have been found to not react as effectively with silane coupling agents of the type traditionally used by the industry. Overcoming these problems will help to better utilize polycarboxy. polymers in fiberglass binders.
Accordingly, it is an objective of the present invention to provide a novel, non-phenol formaldehyde binder.
Yet another object of the present invention is to provide such a binder which allows one to prepare fiberglass insulation products which are less prone to absorb liquid water.
Still another object of the present invention is to provide a fiberglass insulation product which exhibits good recovery and rigidity, and is formaldehyde-free, and is more water-proof.
These and other objects of the present invention will become apparent to the skilled artisan upon a review of the following description and the claims appended hereto.
In accordance with the foregoing objectives, there is provided by the present invention a novel fiberglass binder. The binder composition of the present invention comprises a polycarboxy polymer, a polyol and an imidazoline. It is also preferred that the binder comprise a catalyst, such as an alkaline metal salt of a phosphorus-containing organic acid.
An important aspect of the binder of the present invention is that the imidazoline material is present. The presence of the imidazoline has been found to render the binder, and hence the fiberglass mat to which the binder is applied, essentially water-proof. As a result, fiberglass insulation made with the binder of the present invention avoids problems of coming apart when subjected to water, as the binder of the present invention has been found to better repel the water and maintain the integrity of the bond with the fiberglass. Indeed, it is believed that the imidazoline materials used, primarily due to their hydroxy functionality, act as coupling agents for resin to glass adhesion.
The polycarboxy polymer used in the binder of the present invention comprises an organic polymer or oligomer containing more than one pendant carboxy group. The polycarboxy polymer may be a homopolymer or copolymer prepared from unsaturated carboxylic acids including but not necessarily limited to acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, maleic acid, cinnamic acid, 2-methylmaleic acid, itaconic acid, 2-methylitaeonic acid, alpha, beta-methyleneglutaric acid, and the like. Alternative, the polycarboxy polymer may be prepared from unsaturated anhydrides including, but not necessarily limited to, maleic anhydride, methacrylic anhydride, and the like, as well as mixtures thereof. Methods for polymerizing these acids and anhydrides are well-known in the chemical art.
The polycarboxy polymer of the present invention may additionally comprise a copolymer of one or more of the aforementioned unsaturated carboxylic acids or anhydrides and one or more vinyl compounds including, but not necessarily limited to, styrene, alpha-methylstyrene, aorylonitrile, methacrylonitrile, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, blycidyl methacrylate, vinyl methyl ether, vinyl acetate, and the like. Methods for preparing these copolymers are well-known in the art.
Preferred polycarboxy polymers comprise homopolymers and copolymers of polyacrylic acid. It is particularly preferred that the molecular weight of the polycarboxy polymer, and in particular polyacrylic acid polymer, is less than 10000, more preferably less than 5000, and most preferably about 3000 or less. The low molecular weight polycarboxy polymer, when combined with a low pH binder, results in a final product which exhibits excellent recovery and rigidity.
The formaldehyde-free curable aqueous binder composition of the present invention also contains a polyol containing at least two hydroxyl groups. The polyol must be sufficiently nonvolatile such that it will substantially remain available for reaction with the polyacid in the composition during heating and curing operations. The polyol may be a compound with a molecular weight less than about 1000 bearing at least two hydroxyl groups such as, for example, ethylene glycol, glycerol, pentaerythritol, trimethylol propane, sorbitol, sucrose, glucose, resorcinol, catechol, pyrogallol, glycollated ureas, 1,4-cyclohexane diol, diethanolamine, triethanolamine, and certain reactive polyols such as, for example, hydroxyalkylamides such as, for example, bis[N,N-di(beta-hydroxyethyl)]adipamide, as may be prepared according to the teachings of U.S. Pat. No. 4,076,917, hereby incorporated herein by reference, or it may be an addition polymer containing at least two hydroxyl groups such as, for example, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, and homopolymers or copolymers of hydroxyethyl (meth) acrylate, hydroxypropyl(meth) acrylate, and the like. The most preferred polyol for the purposes of the present invention is triethanolamine (TEA).
The ratio of the number of equivalents of carboxy, anhydride, or salts thereof of the polyacid to the number of equivalents of hydroxyl in the polyol is from about 1/0.01 to about 1/3. An excess of equivalents of carboxy, anhydride, or salts thereof of the polyacid to the equivalents of hydroxyl in the polyol is preferred. The more preferred ratio of the number of equivalents of carboxy, anhydride, or salts thereof in the polyacid to the number of equivalents of hydroxyl in the polyol is from about 1/0.4 to about 1/1. The most preferred ratio of the number of equivalents of carboxy, anhydride, or salts thereof in the polyacid to the number of equivalents of hydroxyl in the polyol is from about 1/0.2 to about 1/0.95, more preferably from 1/0.6 to 1/0.8, and most preferably from 1/0.65 to 1/0.75. A low ratio, approaching 1/0.7 has been found to be of particular advantage in the present invention, when combined with a low molecular weight polycarboxy polymer, and also preferably with a low pH binder.
The binder of the present invention also contains an imidazoline material. The presence of the imidazoline has been found to render the binder less prone to absorb water. As a result, the integrity of the bond between the binder and glass fiber, and hence the integrity of the entire mat product, is better maintained when exposed to liquid water. The binder bond, and hence the overall product, is more water-proof.
The imidazoline of the present invention is preferably based upon the reaction of a fatty acid with an amine. The reaction forms an amide which then undergoes cyclization at elevated temperatures to form the imidazoline. Preferably, the entire reaction product is used as the additive to the binder composition. The reaction product is a mixture of the reactants, intermediates, and final product.
The fatty acid can be any fatty acid, but is preferably selected from stearic acid, oleic acid or tall oil. The amine can also be any suitable amine, but is preferably comprised of an aminoethylethanolamine. Amines such as diethylene triamine can also be used. From a performance standpoint, oleyl hydroxyethyl imidazoline is the most preferred imidazoline for use in the binder of the present invention.
It is also most preferred that the imidazoline be hydroxy functional as it acts as a coupling agent for resin to glass adhesion. Since acrylic resins do not react very effectively with silane coupling agents, this is an additional advantage of the present invention.
It is preferred that the formaldehyde-free curable aqueous binder composition of the present invention also contains a catalyst. Most preferably, the catalyst is a phosphorous-containing accelerator which may be a compound with a molecular weight less than about 1000 such as, for example, an alkali metal polyphosphate, an alkali metal dihydrogen phosphate, a polyphosphoric acid, and an alkyl phosphinic acid or it may be an oligomer or polymer bearing phosphorous-containing groups such as, for example, addition polymers of acrylic and/or maleic adds formed in the presence of sodium hypophosphite, addition polymers prepared from ethylenically unsaturated monomers in the presence of phosphorous salt chain transfer agents or terminators, and addition polymers containing acid-functional monomer residues such as, for example, copolymerized phosphoethyl methacrylate, and like phosphonic acid esters, and copolymerized vinyl sulfonic acid monomers, and their salts. The phosphorous-containing accelerator may be used at a level of from about 1% to about 40%, by weight based on the combined weight of the polyacid and the polyol. Preferred is a level of phosphorous-containing accelerator of from about 2.5% to about 10%, by weight based on the combined weight of the polyacid and the polyol.
It is most preferred that the pH of the binder of the present invention also be low, i.e., no greater than 4.5. For it has been found that the combination of low molecular weight polycarboxy polymer with a lowered pH provides a binder exhibiting minimal processing difficulties and a final product with excellent recovery and rigidity. Maintaining the pH in the range of greater than 3.5 to 4.5 or less, also allows one to avoid serious problems with conversion of the equipment while still realizing the benefits of the low pH.
The formaldehyde-free curable aqueous binder composition may contain, in addition, conventional treatment components such as, for example, emulsifiers, pigments, filler, anti-migration aids, curing agents, coalescents, wetting agents, biocides, plasticizers, organosilanes, anti-foaming agents, colorants, waxes, and anti-oxidants.
The formaldehyde-free curable aqueous binder composition may be prepared by admixing the polyacid, the polyol, and the phosphorous-containing accelerator using conventional mixing techniques. In another embodiment, a carboxyl- or anhydride-containing addition polymer and a polyol may be present in the same addition polymer, which addition polymer would contain both carboxyl, anhydride, or salts thereof functionality and hydroxyl functionality. In another embodiment, the salts of the carboxy-group are salts of functional alkanolamines with at least two hydroxyl groups such as, for example, diethanolamine, triethanolamine, dipropanolamine, and di-isopropanolamine. In an additional embodiment, the polyol and the phosphorous-containing accelerator may be present in the same addition polymer, which addition polymer may be mixed with a polyacid. In yet another embodiment the carboxyl- or anhydride-containing addition polymer, the polyol, and the phosphorous-containing accelerator may be present in the same addition polymer. Other embodiments will be apparent to one skilled in the art. As disclosed herein-above, the carboxyl groups of the polyacid may be neutralized to an extent of less than about 35% with a fixed base before, during, or after the mixing to provide the aqueous composition. Neutralization may be partially effected during the formation of the polyacid.
Once the composition of the polyacid and the polyol has been prepared, the imidazoline can then be mixed in with the composition to form the final composition to be sprayed on the fiberglass. The imidazoline is therefore basically an important additive to conventional binder systems, such as that described in U.S. Pat. No. 6,331,350, which is hereby expressly incorporated by reference in its entirety. As molten streams of glass are drawn into fibers of random lengths and blown into a forming chamber where they are randomly deposited as a mat onto a traveling conveyor, the fibers, while in transit in the forming chamber, are sprayed with the aqueous binder composition of the present invention, which includes the imidazoline.
More particularly, in the preparation of fiberglass insulation products, the products can be prepared using conventional techniques. As is well known, a porous mat of fibrous glass can be produced by fiberizing molten glass and immediately forming a fibrous glass mat on a moving conveyor. The expanded mat is then conveyed to and through a curing oven wherein heated air is passed through the mat to cure the resin. The mat is slightly compressed to give the finished product a predetermined thickness and surface finish. Typically, the curing oven is operated at a temperature from about 150xc2x0 C. to about 325xc2x0 C. Preferably, the temperature ranges from about 180 to about 225xc2x0 C. Generally, the mat resides within the oven for a period of time from about xc2xd minute to about 3 minutes. For the manufacture of conventional thermal or acoustical insulation products, the time ranges from about xc2xe minute to about 1xc2xd minutes. The fibrous glass having a cured, rigid binder matrix emerges from the oven in the form of a bat which may be compressed for packaging and shipping and which will thereafter substantially recover its vertical dimension when unconstrained.
The formaldehyde-free curable aqueous composition may also be applied to a already formed nonwoven by conventional techniques such as, for example, air or airless spraying, padding, saturating, roll coating, curtain coating, beater deposition, coagulation, or the like.
The waterborne formaldehyde-free composition, after it is applied to a nonwoven, is heated to effect drying and curing. The duration and temperature of heating will affect the rate of drying, processability and handleability, and property development of the treated substrate. Heat treatment at about 120xc2x0 C., to about 400xc2x0 C., for a period of time between about 3 seconds to about 15 minutes may be carried out; treatment at about 150xc2x0 C., to about 250xc2x0 C., is preferred. The drying and curing functions may be effected in two or more distinct steps, if desired. For example, the composition may be first heated at a temperature and for a time sufficient to substantially dry but not to substantially cure the composition and then heated for a second time at a higher temperature and/or for a longer period of time to effect curing. Such a procedure, referred to as xe2x80x9cB-stagingxe2x80x9d, may be used to provide binder-treated nonwoven, for example, in roll form, which may at a later stage be cured, with or without forming or molding into a particular configuration, concurrent with the curing process.
The heat-resistant nonwovens may be used for applications such as, for example, insulation batts or rolls, as reinforcing mat for roofing or flooring applications, as roving, as microglass-based substrate for printed circuit boards or battery separators, as filter stock, as tape stock, as tape board for office petitions, in duct liners or duct board, and as reinforcement scrim in cementitious and non-cementitious coatings for masonry.
The following examples are produced in order to further illustrate the present invention, and are not intended to limit the invention.

Imidazoline containing fiberglass binder


An ink composition comprising water, a dye and at least one compound capable of including a dye therein, wherein the dye is dissolved or dispersed in an aqueous medium comprising the water.

This invention relates to ink compositions whereby images with high qualities and high storage stability can be obtained. In particular, it relates to ink compositions favorably used in ink jet recording and an ink jet recording method with the use of the ink compositions.
With the recent popularization of computers, ink jet printers have been widely used in printing on papers, films, fabrics, etc. not only for business purposes but also for household purposes.
There are a number of ink jet recording systems, for example, a system wherein liquid drops are jetted under the application of pressure by a piezoelectric device, a system wherein liquid drops are jetted by using ink bubbles formed by heating, a system with the use of ultrasonic wave, and a system wherein liquid drops are electrostatically sucked and jetted. As inks for these ink jet recording systems, use has been made of water inks, oily inks and solid (melting) inks. Among these inks, water inks have been mainly employed because of being favorable from the viewpoints of easiness in production and handling, smell, safety, etc.
It is required that colorants to be used in these inks for ink jet recording are highly soluble in solvents, enable high-density recording, have favorable color hues, are highly fast to light, heat, air, water and chemicals, have excellent fixation properties to image recording materials with little bleeding, excellent storage properties as inks, no toxicity and high purity, and can be economically obtained. However, colorants satisfying all of these requirements at high levels can be hardly found out.
Although there have been proposed various dyes and pigments for ink jet recording and already put into practical use, no colorant satisfying all of these requirements has been established so far. By using commonly known dyes or pigments with color index (C.I.) numbers, both of the color hues and fastness needed in ink jet recording inks can be hardly achieved.
On the other hand, Japanese Patent Laid-Open No. 74761/1983 and ibid. No. 92369/1985 disclose inks containing glycerol and ethylene oxide adducts of diethylene glycol and alcohols, and Japanese Patent Laid-Open No. 2000-265098 proposes to use ethylene oxide adducts of long chain linear alcohols. However, these inks suffer from a disadvantage that image qualities of images formed thereby are worsened during storage.
Furthermore, Japanese Patent Laid-Open 88048/1994, ibid. No. 333532/1996, ibid. No. 333533/1996, U.S. Pat. No. 5,837,043, ibid. U.S. Pat. No. 5,626,655, etc. propose that bleeding in images can be relieved by using inks containing ethylene oxide adducts of higher alcohols. However, these inks have other disadvantages such as frequently causing plugging and suffering from changes in color tones due to poor image storing properties.
The present invention provides ink compositions having a high jetting stability, being excellent color hue, weatherability and moisture resistance and showing favorable image qualities and an ink jet recording method with the use of the compositions.
The object of the present invention can be achieved by ink compositions and an ink jet recording method as will be specified by the following five items.
1) An ink composition made up of a dye dissolved or dispersed in an aqueous medium characterized in that the ink composition contains water, a water-miscible organic solvent, a dye and at least one compound capable of including a dye therein.
2) An ink composition according to the above 1) characterized in that the above-described compound capable of including a dye therein is a rotaxane molecule or a molecular nanotube.
3) An ink composition according to claim the above 1) or 2) characterized in that each of the compound capable of including a dye therein, rotaxane molecule and molecular nanotube has cyclodextrin as the constitutional unit.
4) An ink composition according to any of the above 1) to 3) characterized in that the ink composition is to be used in ink jet recording.
5) An ink jet recording method comprising jetting ink drops onto an image recording (receiving) material having an image recording layer containing inorganic pigment particles on a substrate in accordance with recording signals and thus recording an image on the image recording material, characterized in that the ink drops are made of an ink composition according to any of the above 1) to 4).
The present invention will be described in greater detail.
The ink composition according to the present invention, which is made up of an aqueous medium composed of water and a water-miscible organic solvent and a dye such as a water-soluble dye or oil-soluble dye dissolved or dispersed in the aqueous medium, contains at least one xe2x80x9ccompound capable of including a dyexe2x80x9d (hereinafter referred to as an inclusion compound) together with the dye. Images (involving characters and diagrams) recorded by using the ink composition according to the present invention have excellent weatherability, which makes it favorable as an ink composition for ink jet recording.
In the present invention, an inclusion compound is defined as a compound which is capable of incorporating a dye molecule in its structure. The term xe2x80x9cinclusion compoundxe2x80x9d means a compound which forms an inclusion lattice in case where two types of molecules are combined together under adequate conditions and one of these molecules forms a tunnel, layered or network structure (i.e., the inclusion lattice) while the other molecule is incorporated within the space (Iwanami Rikagakujiten, 5th ed., p. 1296 (1998)).
It is assumed that the inclusion compound contained in the ink composition according to the present invention has an effect of incorporating (including) the whole water-soluble or oil-soluble dye molecules or a part thereof contained (included) in the ink composition.
As the above-described inclusion compound, use can be made of rotaxanes, molecular nanotubes, crown compounds (18-crown-6,15-crown-5, dibenzo-14-crown-4, dicyclohexyl-18-crown-6, cryptand[2.2.2], etc.), cyclodextrins (xcex1-cyclodextrin, xcex2-cyclodextrin, xcex3-cyclodextrin, etc.), cyclophane, azacyclophane, calixarenes (calix[4]arene, calix[6]arene, calix[8]arene, etc.), cyclotriveratrylene, cavitand, oligopeptide, deoxycholic acid, perhydrotriphenylene, tri-O-thymotide, cyclophosphazene and so on.
In addition to the compounds as cited above, it is also possible to use compounds reported by Fumio Tokuni (Hosetsu Kagobutsu no Kiso to Oyo, NTS (1989)) and Naoya Ogata (Kinousei Chobunshi no Sekkei to Shorai Tenbo, CMC (1998)).
Particularly preferable examples of the inclusion compound to be used in the present invention are rotaxanes, molecular nanotubes, crown ethers, cyclodextrin, azacrown compounds and calixarenes.
In the present invention, it is particularly preferable to use rotaxane molecules and molecular nanotubes which are inclusion compounds having cyclodextrins bonded to each other in tandem (i.e., having cyclodextrin as a constitutional unit) and capable of including a dye therein.
Molecular nanotubes, which are publicly known compounds, are described in detail in Science (1994), 264 (5156), 249-251; J. Phys. Chem. (1996), 100(38), 15562-15568; Kobunshi Ronbunshu (1999), 56(12), 8330836; J. Chem. Phys. (2000), 112(9), 4321-4325;Langmuir (2000), 16(26), 10278-10280; J. Chem. Phys. (2001), 114(1), 1-3; etc.
As the constitutional unit of the molecular nanotubes, use can be made of various compounds such as xcex1-cyclodextrin, xcex2-cyclodextrin and xcex3-cyclodextrin.
The ink composition according to the present invention contains at least one xe2x80x9ccompound capable of including a dye thereinxe2x80x9d. It is preferable that the content of such a compound ranges from 0.1 to 60% by weight, still preferably from 1 to 40% by weight, in 100% by weight of the ink composition.
The ink composition according to the present invention can be produced by dissolving and/or dispersing a dye in an aqueous medium. As the dye, use can be made of various dyes such as azo dyes, azomethin dyes, cyanine dyes, merocyanine dyes, oxonol dyes, quinone dyes and indigo dyes. From the viewpoint of the interaction (inclusion) between the dye and the compound capable of including a dye therein, it is favorable to use azo pigments.
To obtain full-color images or to control the color tone, it is also possible to use other colorants or dyes together.
An aqueous medium is used in the ink composition. The term xe2x80x9caqueous mediumxe2x80x9d means a water or a mixture of water with a small amount of a water-miscible (water-soluble) organic solvent optionally containing additives such as a wetting agent, a stabilizer and a preservative. Furthermore, a surfactant can be used in this system.
Examples of the above-described water-miscible organic solvent usable in the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohdxanol, benzyl alcohol), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerol, hexanetriol, thiodiglycol), glycol derivatives (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, trimethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (for example, formamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone). A mixture of two or more water-miscible organic solvents as cited above may be used.
In case where the above-described dye is an oil-soluble dye, the ink composition can be prepared by dissolving the oil-soluble dye in a high-boiling organic solvent and emulsified/dispersed in an aqueous medium.
The high-boiling organic solvent to be used in the present invention has a boiling point of 150xc2x0 C. or higher, preferably 170xc2x0 C. or higher.
Examples thereof include phthalic acid esters (for example, dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, di-2-ethylhexyl phthalate, decyl phthalate, bis(2,4-di-tert-amylphenyl) isophthalate, bis(1,1-diethylpropyl) phthalate), phosphoric acid or phosphonic acid esters (for example, diphenyl phosphate triphenyl phosphate, tricresyl phosphate, 2-ethylhexyldiphenyl phosphate, dioctylbutyl phosphate, tricyclohexyl phosphate, tri-2-ethylhexyl phosphate, tridodecyl phosphate, di-2-ethyhexylphenyl phosphate), benzoic acid esters (for example, 2-ethylhexyl benzoate, 2,4-dichloro benzoate, dodecyl benzoate, 2-ethylhexyl-p-hydroxy benzoate), amides (for example, N,N-diethyldeane amide, N,N-diethyllauryl amide), alcohols and phenols (for example, isostearyl alcohol, 2,4,-di-tert-amyl phenol), aliphatic esters (for example, dibutoxyethyl succinate, di-2-ethylhexyl succinate, 2-hexyldecyl tetradecanoate, tributyl citrate, diethyl azelate, isostearyl lactate, trioctyl citrate), aniline derivatives (for example, N,N-dibutyl-2-butoxy-5-tert-octyl aniline), chlorinated paraffins (for example, paraffins having a chlorine content of 10% to 80%), trimesic acid esters (for example, tributyl trimesate), dodecylbenzene, diisopropylnaphthalene, phenols (for example, 2,4-di-tert-amylphenol, 4-dodecyloxyphenol, 4-dodecyloxycarbonylphenol, 4-(4-dodecyloxyphenylsulfonyl) phenol), carboxylic acids (for example, 2-(2,4-di-tert-amylphenoxybutyric acid, 2-ethoxyoctanedecanoic acid), and alkylphosphoric acids (for example, di-2(ethylhexyl) phosphoric acid, diphenylphosphoric acid). The high-boiling organic solvent can be used in an amount 0.01 to 3 times by weight, preferably 0.01 to 1.0 times, as much as the oil-soluble dye.
Either one of these high-boiling organic solvent or a mixture of two or more thereof (for example, tricresyl phosphate with dibutyl phthalate, trioctyl phosphate with di(2-ethylhexyl)cebacate, dibutyl phthalate with poly(N-t-butylacrylamide)) may be used.
Examples of the high-boiling organic solvent to be used in the present invention other than those cited above and/or methods of synthesizing these high-boiling organic solvents are described in, for example, U.S. Pat. No. 2,322,027, ibid. U.S. Pat. No. 2,533,514, ibid. U.S. Pat. No. 2,772,163, ibid. U.S. Pat. No. 2,835,579, ibid. U.S. Pat. No. 3,594,171, ibid. U.S. Pat. No. 3,676,137, ibid. U.S. Pat. No. 3,689,271, ibid. U.S. Pat. No. 3,700,454, ibid. U.S. Pat. No. 3,748,141, ibid. U.S. Pat. No. 3,764,336, ibid. U.S. Pat. No. 3,765,897, ibid. U.S. Pat. No. 3,912,515, ibid. U.S. Pat. No. 3,936,303, ibid. U.S. Pat. No. 4,004,928, ibid. U.S. Pat. No. 4,080,209, ibid. U.S. Pat. No. 4,127,413, ibid. U.S. Pat. No. 4,193,802, ibid. U.S. Pat. No. 4,207,393, ibid. U.S. Pat. No. 4,220,711, ibid. U.S. Pat. No. 4,239,851, ibid. U.S. Pat. No. 4,278,757, ibid. U.S. Pat. No. 4,353,979, ibid. U.S. Pat. No. 4,363,873, ibid. U.S. Pat. No. 4,430,421, ibid. U.S. Pat. No. 4,430,422, ibid. U.S. Pat. No. 4,464,464, ibid. U.S. Pat. No. 4,483,918, ibid. U.S. Pat. No. 4,540,657, ibid. U.S. Pat. No. 4,684,606, ibid. U.S. Pat. No. 4,728,599, ibid. U.S. Pat. No. 4,745,049, ibid. U.S. Pat. No. 4,935,321, ibid. U.S. Pat. No. 5,013,639, EP276,319A, ibid. 286,253A, ibid. 289,820A, ibid. 309,158A, ibid. 309,159A, ibid. 309,160A, ibid. 509,311A, ibid. 510,576A, East Germany Patent No. 147,009, ibid. No. 157,147, ibid. No. 159,573, ibid. No. 225,240A, U.K. Patent No. 2,091,124A, Japanese Patent Laid-Open No. 47335/1973, ibid. No. 26530/1975, ibid. No. 25133/1976, ibid. No. 26036/1976, ibid. No. 27921/1976, ibid. No. 27922/1976, ibid. No. 149028/1976, ibid. No. 46816/1977, ibid. No. 1520/1978, ibid. No. 1521/1978, ibid. No. 15127/1978, ibid. No. 146622/1978, ibid. No. 91325/1979, ibid. No. 106228/1979, ibid. No. 118246/1979, ibid. No. 59464/1980, ibid. No. 64333/1980, ibid. No. 81836/1981, ibid. No. 204041/1984, ibid. No. 84641/1986, ibid. No. 118345/1987, ibid. No. 247364/1987, ibid. No. 167357/1988, ibid. No. 214744/1988, ibid. No. 301941/1988, ibid. No. 9452/1989, ibid. No. 9454/1989, ibid. No. 68745/1989, ibid. No. 101543/1989, ibid. No. 102454/1989, ibid. No. 792/1990, ibid. No. 4239/1990, ibid. No. 43541/1990, ibid. No. 29237/1992, ibid. No. 30165/1992, ibid. No. 232946/1992 and ibid. No. 346338/1992.
The high-boiling organic solvent described above is used in an amount 0.01 to 3.0 times by weight, preferably 0.01 to 1.0 times, as much as the oil-soluble dye.
In the present invention, the oil-soluble dye and the high-boiling organic solvent are used in the state of being emulsified/dispersed in the aqueous medium. From the viewpoint of emulsification, use can be also made of a low-boiling organic solvent in the step of the emulsification/dispersion. The term xe2x80x9clow-boiling organic solventxe2x80x9d means an organic solvent having a boiling point of 30xc2x0 C. or higher but not higher than 150xc2x0 C. under atmospheric pressure. Preferable examples thereof include esters (for example, ethyl acetate, butyl acetate, ethyl propionate, xcex2-ethoxyethyl acetate, methylcellosolve acetate), alcohols (for example, isopropyl alcohol, n-butyl alcohol, secondary butyl alcohol), ketones (for example, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone), amides (for example, dimethylformamide, N-methylpyrrolidone) and ethers (for example, tetrahydrofuran, dioxane), though the present invention is not restricted thereto.
The emulsification/dispersion can be carried out by dispersing an oily phase, in which the dye has been dissolved in the high-boiling organic solvent optionally mixed with the low-boiling organic solvent, in an aqueous phase containing water as the major component and thus forming microdrops of the oily layer. In this step, it is possible to add additives such as a wetting agent, a dye stabilizer, an emulsion stabilizer, a preservative and a mildew-proofing agent as will be described hereinafter either one or both of the aqueous phase and the oily phase.
For the emulsification, it has been a common practice to add the oily phase to the aqueous phase. It is also favorable to use the so-called phase inversion emulsification method wherein the aqueous phase is dropped into the oily phase.
In the emulsification/dispersion in the present invention, use can be made of various surfactants. For example, it is preferable to use anionic surfactants such as fatty acid salts, alkyl sulfates, alkyl benzenesulfonates, alkyl naphthalenesulfonates, dialkyl sulcosuccinates, alkyl phosphates, napthalenesulfonic acid-formalin condensate or polyoxyethylene alkyl sulfates, or nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylamines, glycerol fatty acid esters and oxyethylene-oxypropylene block copolymer. Also, SURFYNOLS (manufactured by Air Products and Chemicals) which are acetylene-based polyoxyethylene oxide surfactants can be preferably employed. It is also preferable to use amphoteric surfactants such as N,N-dimethyl-N-alkylamine oxides. Furthermore, use can be made of surfactants cited in Japanese Patent Laid-Open No. 157,636/1984, pp. (37) to (38) and Research Disclosure NO. 308119 (1989).
To stabilize the dispersion immediately after the emulsification, a water-soluble polymer may be added together with the above-described surfactant. As the water-soluble polymer, it is preferable to use polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, polyacrylic acid, polyacrylamide and copolymers thereof. It is also preferable to use natural water-soluble polymers such as polysaccharides, casein and gelatin. To further stabilize the dye dispersion, it is also possible to use polyvinyls, polyurethanes, polyesters, polyamides, polyuretahens, polycarbonates, etc. which are obtained by polymerizing acrylic acid esters, methacrylic acid esters, vinyl esters, acrylamides, methacrylamides, olefins, styrenes, vinyl ethers and acrylonitriles and are substantially insoluble in the aqueous medium. It is preferable that these polymers contain xe2x80x94SO2xe2x88x92 or xe2x80x94COOxe2x88x92. In case of using such a polymer substantially insoluble in the aqueous medium, it is preferable to use the polymer in an amount of not more than 20% by weight, still preferably not more than 10% by weight, based on the high-boiling organic solvent.
In case of dispersing the oil-soluble dye and the high-boiling organic solvent by emulsification/dispersion to prepare a water ink, it is specifically important to control the particle size. To enhance the color purity and density in forming an image by ink jet recording, it is essentially required to lessen the average particle size. It is preferable that the volume-average particle size is 1 xcexcm or less, still preferably from 5 to 100 nm.
The volume-average particle size of the dispersed particles as described above and the particle size distribution can be easily measured by using a publicly known method, for example, the static light scattering method, the dynamic light scattering method, the centrifugation method or the methods cited in Jikken Kagaku Koza, Eth ed., pp. 417 to 418. For example, the ink is diluted with distilled water to give a particle concentration in the ink of 0.1 to 1% by weight. Then, measurement can be easily made by using a marketed volume-average particle size measuring apparatus, for example, MICROTRACK UPA (manufactured by Nikkiso). It is particularly preferable to use the dynamic light scattering method by taking advantage of the laser Doppler effect, since even a very small particle size can be measured thereby.
The term xe2x80x9cvolume-average particle sizexe2x80x9d means the average particle size weighed with particle diameter. It is calculated by dividing the grand total of the products of the particle size by the volume of individual particles by the total volume of the particles. Volume-average particle diameter is described in xe2x80x9cKobunshi Ratekkusu no Kagakuxe2x80x9d, Soichi Muroi, Kobunshi Kanko-kai, p. 119.
It has been also clarified that the existence of coarse particles largely affects the printing performance. Namely, coarse particles cause plugging in head nozzles or staining, though not plugging. As a result, there arise jetting errors or twisting, thereby seriously affecting the printing performance. To prevent these phenomena, it is important to regulate the concentrations of particles of 5 xcexcm or more in size and particles 1 xcexcm or more in size respectively to 10 or less and 1000 or less per xcexcl of ink.
To eliminate these coarse particles, use can be made of a publicly known method such as centrifugation or microfiltration. Such a separating procedure may be carried out either immediately after the emulsification/dispersion or after adding various additives such as a wetting agent and a surfactant to the emulsified dispersion immediately before packing in an ink cartridge.
As effective means of lessening the average particle size and eliminating coarse particles, a mechanical emulsifying apparatus can be employed.
As an emulsifying apparatus, use can be made of a publicly known apparatus, for example, a simple stirrer, an impeller stirrer system, an inline stirrer system, a mill such as a colloid mill or an ultrasonic system. It is particularly preferable to use a high pressure homogenizer.
Detailed mechanism of the high pressure homogenizer is described in U.S. Pat. No. 4,533,254, Japanese Patent Laid-Open No. 47264/1994, etc. As marketed apparatus, there are known Gaulin Homogenizer (manufactured by A.P.V. GAULIN INC.), Microfluidizer (manufactured by MICROFLUIDEX INC.), Altimizer (manufactured by K.K. Sugino Machine), etc.
Moreover, a high pressure homogenizer provided with a mechanism of forming microparticles in an ultrahigh pressure jet stream, which is recently proposed by U.S. Pat. No. 5,720,551, is particularly effective in the emulsification/dispersion in the present invention. As an example of this emulsifying apparatus with the use of an ultrahigh pressure jet stream, DEBEE2000 (manufactured by BEE INTERNATIONAL LTD.) may be cited.
The pressure employed in the emulsification with the high pressure emulsifying/dispersing apparatus is 50 MPa or above, preferably 60 MPa or above and still preferably 180 MPa or above.
It is particularly preferable to use two or more types of emulsifying apparatuses in combination as, for example, emulsifying with a stirrer-type emulsifying apparatus and then passing the emulsified product through a high pressure homogenizer. It is also preferable that after emulsifying/dispersing in such an emulsifying apparatus, additives such as a wetting agent and a surfactant are added and then the obtained ink is further passed through a high pressure homogenizer before packing into an ink cartridge.
In case of containing a low-boiling organic solvent in addition to a high-boiling organic solvent, it is favorable to remove the low-boiling solvent from the viewpoints of the stability of the emulsion and safety and hygiene. The low-boiling organic solvent can be removed by using various publicly known methods such as evaporation, vacuum evaporation or ultrafiltration. It is favorable to carry out this procedure of removing the low-boiling organic solvent as immediately as possible after the emulsification.
The ink composition obtained in the present invention may contain appropriately selected additives such as a drying inhibitor for preventing plugging at ink jet nozzles due to dryness, a penetration accelerator for more smooth penetration of the ink into paper, an UV absorber, an antioxidant, a viscosity controlling agent, a surface tension controlling agent, a dispersing aid, a dispersion stabilizer, a mildew-proofing agent, a rust preventive, a pH adjustor, a defoaming agent and a chelating agent each in an appropriate amount.
As the drying inhibitor to be used in the present invention, it is preferable to select a water-soluble organic solvent having a vapor pressure lower than water. Specific examples thereof include polyhydric alcohols typified by ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycol derivatives, glycerol and trimethylolpropane; lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether and triethylene glycol monoethyl (or butyl) ether; heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and N-ethylmorpholine; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide and 3-sulfolene; polyfunctional compounds such as diacetone alcohol and diethanolamine; and urea derivatives. Among these compounds, polyhydric alcohols such as glycerol and diethylene glycol are preferable therefor. Either one of these drying inhibitors or two or more thereof may be used. It is preferable that such a drying inhibitor is contained in an amount of from 10 to 50% by weight in the ink.
As the penetration accelerator to be used in the present invention, use can be made of alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether and 1,2-hexanediol, sodium lauryl sulfate, sodium oleate and nonionic surfactants. Since such a penetration accelerator exerts a sufficient effect at a content of 10 to 30% by weight in the ink, it is preferably used in such an extent as not causing bleeding in printing or print-through.
As the UV absorber to be used in the present invention to improve the storage stability of images, use can be made of benzotriazole-type compounds described in Japanese Patent Laid-Open No. 185677/1983, ibid. No. 190537/1986, ibid. No. 782/1990, ibid. No. 197075/1993, ibid. No. 34057/1997, etc.; benzophenone-type compounds described in Japanese Patent Laid-Open No. 2784/1971, ibid. No. 194483/1994, U.S. Pat. No. 3,214,463, etc.; cinammic acid-type compounds described in Japanese Patent Publication No. 30492/1973, ibid. No. 21141/1981, Japanese Patent Laid-Open No. 88106/1998, etc.; triazine-type compounds described in Japanese Patent Laid-Open No. 298503/1992, ibid. No. 53427/1996, ibid. No. 239368/1996, ibid. No. 182621/1998, International Patent Publication No. 501291/1996, etc.; and compounds which absorb UV light and emit fluorescence (i.e., so-called fluorescent brighteners) typified by compounds described in Research Disclosure No. 24239 and stilbene- and benzoxazole-type compounds.
As the antioxidant to be used in the present invention for improving storage stability of images, use can be made of various organic and metal complex-based fading inhibitors. Examples of organic fading-inhibitors include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indans, chromans, alkoxyanilines and heterocyclic compounds, while examples of the metal complexes include nickel complexes and zinc complexes. More specifically, use can be made of compounds cited in Research Disclosure No. 17643, VII, I to J, ibid. No. 15162, ibid. No. 18716, p. 650, left column, ibid. No. 36544, p. 527, ibid. No. 307105, p. 872 and ibid. No. 15162 and compounds included in the general formula of typical compounds and examples of compounds described in Japanese Patent Laid-Open No. 215272/1987, pp. 127 to 137.
Examples of the mildew-proofing agent to be used in the present invention include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hyrdoxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof. It is preferable that such a mildew-proofing agent is used in an amount of 0.02 to 5.00% by weight in the ink.
These compounds are described in detail in xe2x80x9cBokin Bobizai Jitenxe2x80x9d (ed. by Nihon Bokin Bobi Gakkai Jiten Henshu Iinkai), etc.
Examples of the rust preventive include acidic sulfites, sodium thiosulfate, ammon thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and benzotriazole. It is preferable to use such a rust preventive in an amount of 0.02 to 5.00% by weight in the ink.
In the present invention, it is preferable to use a pH adjustor from the viewpoints of adjusting the pH value, imparting dispersion stability and so on. It is preferable to add the pH adjustor to give a pH value of 4.5 to 10.0, still preferably 6 to 10.0.
Examples of the pH adjustor include basic ones such as organic bases and inorganic alkalis and acidic ones such as organic acids and inorganic acids.
Examples of the above-described organic bases include triethanolamine, diethanolamine, N-methyldiethanolamine and dimethylethanolamine. Examples of the above-described inorganic alkalis include alkali metal hydroxides (for example, sodium hydroxide, lithium hydroxide, potassium hydroxide), carbonic acid salts (for example, sodium carbonate, sodium hydrogencarbonate) and ammonia.
Examples of the above-described organic acids include acetic acid, propionic acid, trifluoroacetic acid and alkylsulfonic acids. Examples of the above-described inorganic acids include hydrochloric acid, sulfuric acid and phosphoric acid.
Separately from the surfactants as described above, nonionic, cationic or anionic surfactants may be used in the present invention as a surface tension controlling agent. Examples of the anionic surfactant include fatty acid salts, alkyl sulfates, alkyl benzenesulfonates, alkyl naphthalenesulfonates, dialkyl sulcosuccinates, alkyl phosphates, napthalenesulfonic acid-formalin condensate and polyoxyethylene alkyl sulfates. Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylamines, glycerol fatty acid esters and oxyethylene-oxypropylene block copolymer. Also, SURFYNOLS (manufactured by Air Products and Chemicals) which are acetylene-based polyoxyethylene oxide surfactants can be preferably employed. It is also preferable to use amphoteric surfactants such as N,N-dimethyl-N-alkylamine oxides. Furthermore, use can be made of surfactants cited in Japanese Patent Laid-Open No. 157,636/1984, pp. (37) to (38) and Research Disclosure No. 308119 (1989).
It is preferable that the ink according to the present invention has a surface tension of from 20 to 60 mN/m, still preferably form 25 to 45 mN/m, with or without the use of these agents.
It is preferable that the ink to be used in the present invention has a viscosity of 30 mPaxc2x7s or less. It is still preferable that the viscosity is controlled to 20 mPaxc2x7s or less. To control the viscosity, a viscosity controlling agent is used in some cases. Examples of the viscosity controlling agent include water-soluble polymers such as celluloses and nonionic surfactants. More specifically, these agents are described in xe2x80x9cNendo Chosei Gijutsuxe2x80x9d (Gijutsu Joho Kyokai, 1999), Chap. 9 and xe2x80x9cInku Jetto Purinta-yo Kemikaruzu (rev. 98)xe2x80x94Zairyo no Kaihatsu Doko Tenbo Chosaxe2x80x94xe2x80x9d (CMC, 1997), pp. 162 to 174.
In the present invention, it is also possible to use above-described cationic, anionic and nonionic surfactants as a dispersion stabilizer, fluorine- and silicone-based compounds as a defoaming agent, and a chelating agent typified by EDTA, if needed.
Next, recording papers and recording films to be used in the image recording method according to the present invention will be described. As the substrate of the recording papers and the recording films, use can be made of substrates which are produced by using a chemical pulp such as LBKP or NBKP, a mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP and CGP, a recycled fiber such as DIP, etc., adding, if necessary, various publicly known additives such as a pigment, a binder, a sizing agent, a fixation agent, a cationic agent and a paper strengthening agent, and treating the mixture with various apparatuses such as a long net paper machine or a circular net paper machine. In addition to such substrates, use can be also made of synthetic paper or plastic film sheets. It is desirable that the substrate has a thickness of from 10 to 250 xcexcm and a basis weight of from 10 to 250 g/m2.
An image recording layer and a back coat layer may be directly formed on the substrate to give an image recording material. Alternatively, a size press or an anchor coat layer may be formed by using starch, polyvinyl alcohol, etc. followed by the formation of the image recording layer and the back coat layer to give an image recording material. Moreover, the surface of the substrate may be flattened by using a calendering apparatus such as a machine calender, a TG calender or a soft calender.
As the substrate in the present invention, it is still preferable to use papers and plastic films coated on both faces with a polyolefin (for example, polyethylene, polystyrene, polyethylene terephthalate and copolymers thereof). It is favorable that the polyolefin contains a white pigment (for example, titanium oxide, zinc oxide) or a tinting dye (for example, cobalt blue, ultramarine, neodymium oxide).
The image recording layer formed on the substrate contains a porous material and an aqueous binder. It is preferable that the image recording layer contains a pigment. It is preferable to use an inorganic pigment, still preferable a white pigment. Examples of the white pigment include inorganic white pigments such as calcium carbonate, kaolin, talc, clay, diatomaceous earth, synthetic amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, alumina, lithopone, zeolite, barium sulfate, calcium sulfate, titanium dioxide, zinc sulfide and zinc carbonate; and organic pigments such as styrene-based pigments, acrylic pigments, urea resins and melamine resins. It is preferable to use a porous inorganic pigment, still preferably synthetic amorphous silica etc. having a large pore area. As the synthetic amorphous silica, either silicic anhydride obtained by dry method or water-containing silicic acid obtained by the wet method can be used. It is particularly desirable to use water-containing silicic acid. Two or more of these pigments may be used combinedly.
Examples of the aqueous binder contained in the image recording layer include water-soluble polymers such as polyvinyl alcohol, silanol-denatured polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyalkylene oxides and polyalkylene oxide derivatives; and water-dispersible polymers such as stryene butadiene latex and acrylic emulsion. Either one of these aqueous binders or a mixture of two or more thereof may be used. Among all, it is particularly adequate in the present invention to use polyvinyl alcohol or silanol-denatured polyvinyl alcohol from the viewpoint of the adhesiveness to a pigment and peeling resistance of the image recording layer.
In addition to the pigment and the aqueous binder, the image recording layer may contain additives such as a mordant, a water-proofing agent, a light-fastness improving agent, a surfactant and a film hardener.
It is preferable that the mordant to be added to the image recording layer has been immobilized. From this viewpoint, it is preferable to use a polymer mordant.
Polymer mordants are described in Japanese Patent Laid-Open No. 28325/1973, ibid. No. 74430/1979, ibid. No. 124726/1979, ibid. No. 22766/1980, ibid. No. 142339/1980, ibid. No. 23859/1985, ibid. No. 23851/1985, ibid. No. 23852/1985, ibid. No. 23853/1985, ibid. No. 57836/1985, ibid. No. 60643/1985, ibid. No. 118834/1985, ibid. No. 122940/1985, ibid. No. 122941/1985, ibid. No. 122942/1985, ibid. No. 235134/1985, ibid. No. 161236/1989, U.S. Pat. No. 2,484,430, ibid. U.S. Pat. No. 2,548,564, ibid. U.S. Pat. No. 3,148,061, ibid. U.S. Pat. No. 3,309,690, ibid. U.S. Pat. No. 4,115,124, ibid. U.S. Pat. No. 4,124,386, ibid. U.S. Pat. No. 4,193,800, ibid. U.S. Pat. No. 4,273,853, ibid. U.S. Pat. No. 4,282,305 and ibid. U.S. Pat. No. 4,450,224. In particular, image recording layers containing the polymer mordants described in Japanese Patent Laid-Open N. 161236/1989, pp. 211 to 215. Use of the polymer mordants described in this document makes it possible to obtain images having excellent qualities and improved light-fastness.
The water-proofing agent is effective in making images water-proof. As the water-proofing agent, it is particularly desirable to use a cationic resin. Examples of such a cationic resin include polyamide-polyamine epichlorhydrin, polyethyleneimine, polyamine sulfone, dimethyldiallylammonium chloride polymers, cationic polyacrylamide and colloidal silica. Among these cationic resins, polyamide-polyamine epichlorhydrin is particularly preferable. It is preferable that such a cationic resin is contained in an amount of from 1 to 15% by weight, still preferably from 3 to 10% by weight, based on the total solid matters in the ink receptor layer.
Examples of the light-fastness improving agent include zinc sulfate, zinc oxide, hindered amine-type antioxidants and benzophenone-type or benzotriazole-type UV absorbers. Among all, zinc oxide is appropriate therefor.
The surfactant serves as an application aid, a peeling properties improving agent, a slipperiness improving agent or an antistatic agent. Surfactants are described in Japanese Patent Laid-Open No. 173463/1987 and ibid. No. 183457/1987.
As a substitute for the surfactant, use may be made of an organic fluoro compound. It is preferable that this organic fluoro compound is a hydrophobic compound. Examples of the organic fluoro compound include fluorine-based surfactants, oily fluorine compounds (for example, fluorine oil) and solid fluorine compounds (for example, tetrafluoroethylene resin). Organic fluoro compounds are described in Japanese Patent Publication No. 9053/1982 (columns 8 to 17), Japanese Patent Laid-Open No. 20994/1986 and ibid. No. 135826/1987.
As the film hardener, use can be made of materials described in Japanese Patent Laid-Open No. 161236/1989, etc.
As other additives to be added to the image recording layer, a pigment dispersing agent, a thickener, a defoaming agent, a dye, a fluorescent brightener, a preservative, a pH adjustor, a matting agent, a film hardener, etc. can be cited. Either one or two image recording layers may be formed.
The recording papers and recording films can be further provided with a back coat layer which may contain a white pigment, an aqueous binder and the like.
Examples of the white pigment contained in the back coat layer include inorganic white pigments such as light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudonboehmite, aluminum hydroxide, alumina, lithopone, zeolite, water-containing halloysite, magnesium carbonate and magnesium hydroxide; and organic pigments such as styrene-based plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins and melamine resins.
Examples of the aqueous binder contained in the back coat layer include water-soluble polymers such as styrene/maleate copolymers, styrene/acrylate copolymers, polyvinyl alcohol, silanol-denatured polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, hydroxyethylcellulose and polyvinylpyrrolidone; and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion. Other additives contained in the back coat layer include a defoaming agent, a foaming inhibitor, a dye, a fluorescent brightener, a preservative and a water-proofing agent.
The layers constituting ink jet recording papers and recoding films (including back layer) may further contain a dispersion of polymer microparticles. The dispersion of polymer microparticles is used in order to improve the film properties such as dimensional stability, anti-curling properties, anti-adhesion properties, and anti-cracking properties. Dispersions of polymer microparticles are described in Japanese Patent Laid-Open No. 245258/1987, ibid. No. 136648/1987 and ibid. No. 110066/1987. By adding a dispersion of polymer microparticles having a low glass transition temperature (40xc2x0 C. or below) to a layer containing a mordant, the layer can be prevented from cracking and curling. Also, the back layer can be prevented from curling by adding a dispersion of polymer microparticles having a high glass transition temperature.
In the present invention, the ink jet recording system is not particularly restricted. Therefore, the present invention is applicable to publicly known systems such as the charge-controlling system of jetting an ink by using electrostatic attraction, the drop-on-demand system (pressure pulse system) by using the vibration pressure of a piezoelectric device, the acoustic ink jet system of converting electric signals into acoustic beams and irradiating an ink therewith to jet the ink due to the radiation pressure, the thermal ink jet (bubble jet) system of bubbling an ink by heating and using the thus generated pressure, etc.
The ink jet systems include a system wherein a great number of small-volume drops of an ink having a low density (i.e., a photoink) are jetted, a system wherein a plural number of inks having substantially the same color hue but different densities are used for improving image qualities, and a system wherein a colorless and transparent ink is used.

Ink compositions and ink jet recording method