Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
2002-07-22
2004-07-27
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C428S311110, C428S312200, C428S312400, C428S312600, C428S320200, C428S321100, C428S402000, C428S447000, C428S537100, C428S537500, C428S540000, C427S553000, C427S557000, C427S226000, C427S384000
Reexamination Certificate
active
06767620
ABSTRACT:
The present application relates to porous materials given coloured pigmentation with organic pigments localized in their pores and to a process for their preparation.
Porous materials are commonly coloured with dyes that are applied, for example, as stains. In order to achieve satisfactory colouring results with this method a requirement is that the porous material to be coloured has a high and uniform affinity for the dye; this requirement, however, is seldom met. Porous materials coloured with dyes possess, moreover, an undesirably low light stability, and in contact with water or organic liquids (beverages, for example) marks may be formed on articles that are in contact with the materials, since the dyes are in some cases leached out again.
Another method of imparting a coloured appearance to porous materials is to provide them with a pigmented coating. This method, however, has the disadvantage that the pores become sealed by the pigmented coating material, with the result that it becomes difficult if not impossible to perceive visually the nature of the porous material. This is a great disadvantage, especially with natural porous materials, since it is their properties, especially their natural appearance and their permeability, that are the most prized. The properties of the porous material, however, are impaired by a pigmented coating.
EP 648 770 and EP 648 817 disclose carbamate-functional, soluble chromophors which can be converted to the corresponding pigments by heating them to relatively high temperatures, with the ensuing elimination of the carbamate radicals. These compounds are suitable for the mass colouring of polymers and, according to EP 654 711, for the colouring of resists and of polymer coats to which they are applied. Compounds of the same type but with improved properties are known from EP 742 556 and U.S. application Ser. No. 09/013,659.
U.S. Pat. No. 5,243,052 discloses carbonates of quinophthalones, which are of limited solubility and can be used in heat-sensitive recording systems. The leuco dye is embedded within a polymer, preferably in polyethyloxazoline.
Soluble derivatives of triphenylmethane dyes are known from U.S. Pat. No. 4,826,976. They are likewise used in heat-sensitive recording systems, together with a binder such as cellulose acetate-butyrate, polyvinylpyrrolidone or copolymerized ethylene/maleic anhydride.
EP 742 556, furthermore, describes textured pigmentary coatings which are prepared from soluble or meltable precursors and which cover all or part of a substrate surface. The substrates mentioned include fibres and fabrics. It has been found, however, that these pigmentary coatings fail to meet high requirements in terms, in particular, of their rub fastness.
Also known, finally, are numerous heat-sensitive recording systems in which colourless precursors of colorants—as solids, in the form, for example, of aqueous suspensions, together with binders and with or without fillers—are incorporated as the recording layer. For example, JP 04/123,175 describes leucoindigoid derivatives. Colorants in solid form, however, like conventional pigments, for example, make hardly any entry into the pores but for the most part remain, undesirably, on the surface.
It has now surprisingly been found that porous materials can be coloured without impairing their properties, and especially without clogging the pores, if fragmentable pigment precursors in melted or dissolved form are introduced into the pores and then converted to their pigmentary form.
Depending on the solvent, pressure, temperature and treatment time it is possible, surprisingly, to influence the depth of penetration of the pigment precursor and so with great advantage to obtain—in a targeted manner, for example—colorations wherein the pigment is very close to the surface. Since in this case the entirety of the pigment contributes to colouring, it is possible with advantage to reduce its amount to the minimum necessary for coloration, and the colour of the material core remains unaltered.
It is, however, also possible to obtain very high colour saturations (chroma) by using high pigment concentrations. Thus, pigmented porous materials of fine particle size can be used as pigments for colouring high molecular mass organic material. The results are excellent with respect to hue and chroma as well as also to the transparency, when the porous material has a refraction index similar to that of the substrate into which it is incorporated. Very advantageously, these products are less dusting and more easily incorporated into substrates than usual transparent pigments, and rheology problems can be avoided.
Under appropriate conditions it is also possible, however, to provide porous materials with uniform colouring right through, hence allowing them with little or no change in colour to be processed, for example cut, milled, sanded, bent or joined—by gluing, for instance. Consequently, either finished articles or raw material, as desired, can be coloured prior to its processing or shaping.
A particularly advantageous result of this is an increase in production flexibility, and possibilities for making savings, when producing articles from coloured porous materials.
The resulting colorations are surprisingly strong in colour, fast to weathering, light and heat, rubbing, water and solvent, and are also highly uniform optically provided the material itself is uniform in its porosity. With particular advantage this permits the use of materials whose quality would not enable any satisfactory results to be obtained on conventional colouring, a feature which, especially in the case of naturally occurring organic porous materials of complex structure, such as wood, leather or hair, for example, paves the way for ecologically significant, improved utilization of natural resources. A further great advantage is that following the colouring of the porous material its nature is, surprisingly, still apparent to the eye.
The present invention accordingly provides a coloured porous material comprising in its pores an effectively colouring amount of an organic pigment which is obtainable by fragmenting a meltable or solvent-soluble pigment precursor.
Porous materials can be mineral or organic, natural, refined or synthetic. The material may, for example, be chalk, pumice, fired clay, unglazed porcelain, gypsum, concrete, kieselguhr, silica gel, zeolites, wood, paper, leather, imitation leather or hair, in whatever form, or products derived from these. It is preferably a material composed of refined or unrefined organic components of natural origin or, with particular preference, is a refined or unrefined natural organic material. In particular, it can be either hard wood or soft wood.
In another preferred embodiment, however, the material consists of fine particles, most preferably inorganic particles, such as chalk, pumice, fired clay, unglazed porcelain, gypsum, kieselguhr, silica gel or zeolite powders. The particle size is preferably from 0.1 to 10 &mgr;m, most preferably from 1 to 3 &mgr;m. The organic pigment's concentration may be low or high, depending of the desired colour saturation. A low concentration of the organic pigment in the powdered inorganic material leads to pastel tints, while a high concentration of the organic pigment in the powdered inorganic material leads to higher saturations.
Examples of high molecular mass organic materials which can be coloured or pigmented with the instant pigmented porous material powders are cellulose ethers, cellulose esters, such as ethylcellulose, nitrocellulose, cellulose acetate and cellulose butyrate, natural resins or synthetic resins, such as addition polymerization resins or condensation polymerization resins, such as amino resins, especially urea-formaldehyde and melamine-formaldehyde resins, alkyd resins, phenolic resins, polycarbonates, polyolefins, polystyrene, polyvinyl chloride, polyamides, polyurethanes, polyesters, ABS, polyphenylene oxides, rubber, casein, silicone and silicone resins, individually or in mixtures.
The abovementioned hi
Bujard Patrice
Dubas Henri
Hao Zhimin
Verhoustraeten Patrick
Zambounis John
Ciba Specialty Chemicals Corporation
Stevenson Tyler A.
Yamnitzky Marie
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