Patent Description:
The present invention in general relates to resin formulation and in particular, to resin formulation that dries under standard temperature and pressure to form a coating amenable for use as a marker with rapid drying compared to the prior art.

Inspection paints are used in myriad applications to visually detect movement or tampering. Such paints are configured to adhere to, and form a breakable marking seal between, adjacent items that may undergo relative movement. For example, inspection paints may be applied to compression fittings, baseplates, studs, nuts, bolts, screws, fasteners, instrument and gauge housings and calibration mechanisms, parts and numerous other assemblies. Once dry, inspection paints become brittle and will crack if disturbed. Thus, when applied to adjacent items, inspection paints may be used to determine whether the two items have undergone relative movement. As a result, such pens are used extensively, in complex assembly and maintenance associated with aircraft, engines, and vehicles.

By way of example, inspection paints may be applied to the lug nuts attaching a vehicle wheel to an axle. Once the lug nuts are applied to the studs and properly torqued, inspection paint may be applied across the stud and the lug nut. Should the lug nut happen to loosen from the stud as a result of vibration or other means, the inspection paint marking will break, signaling that the lug nut has loosened. Similarly, an inspection paint may be applied to screws fastening the sealed chassis of an electronic device, such as a television. If the chassis is opened without authorization, the inspection paint marking will break, indicating a potential warranty tampering situation.

While state-of-the art current surface marker formulations sold under the tradename CROSS CHECK™ have numerous attractive attributes including drying to a hard film, compliance with BOEING® specification BMS8-<NUM>, adhesion to many substrates, and resistance to several common cleaning solvents. <CIT> is representative of such formulations. Nevertheless, there is a trend towards phosphate ester based hydraulic fluids and other fluid changes to improve the environmental and safety of vehicles. There hydraulic fluids and operational fluids are often characteristics by improved fire resistance and improved longevity/thermal operation profiles, relative to conventional alkane based fluids. Representative of conventional phosphate ester hydraulic fluids are SKYDROL® <NUM> and PE-<NUM>, and HYJET V®, produced by Eastman Chemical and Exxon, respectively. As a result, existing surface marker formulations likewise need to adjust to the requirements of quick drying and modified types of solvent resistance.

Thus, there exists a need for a surface marker formulation that is compatible with contact with phosphate ester based hydraulic fluids. There further exists a need for such a marker formulation that dries to a hard film and does so on a time scale compatible with assembly and maintenance work flow. <CIT> relates to non-yellowing, low-viscosity, unsaturated, amorphous polyesters which are largely free of benzene and formaldehyde, and a process for their preparation and their use as an adhesive component in coating compositions for metallic, mineral substrates or for substrates made of wood and plastics, whereby the adhesion of these coating material compositions is improved even under critical climatic conditions.

A surface marker resin formulation is provided that includes a linear aromatic polyester or a co-polymer thereof containing at least <NUM> monomer percent of aromatic polyester subunits present in an amount of <NUM> to <NUM> total weight percent. The resin is dissolved or dispersed in a solvent. A colorant package is also dissolved or dispersed in the solvent. Upon drying of the solvent a mark is provided on a surface that can alert a user as to relative movement between articles defining the surface.

A process of marking a surface includes two articles being brought into a pre-selected alignment to define a surface. A continuous bead is applied to the surface. The solvent evaporates to a state of dry-to-touch in a time of between <NUM> and <NUM> minutes to mark the surface. Often the surface is a torqued interface between the articles, as found on vehicles. The formulation is readily applied from a pen to achieve a controlled bead width. The drying of the formulation by solvent evaporation can occur in <NUM> to <NUM> minutes under standard temperature and pressure. The resulting mark can withstand at least one hour of immersion contact with a phosphate ester.

The present invention has utility as surface marker formulation and a marker pen containing such a formulation that is able to afford tamper indicating markings to a variety of substrates associated with vehicles, including torque indication. An inventive formulation is resistant to immersion in phosphate ester hydraulic fluid for more than <NUM> minutes after drying. In some inventive embodiments, an inventive formulation is dry to the touch in <NUM> seconds or less, as measured at standard temperature and pressure (STP). An inventive formulation accepts a variety of conventional pigment and dye packages to provide a spectrum of colors and levels of fluorescence.

It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range of from <NUM> to <NUM> is intended to include <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>.

An inventive surface marker formulation is based on a solvent dispersed resin that dries on a target substrate to a desired film that retains a pigment or dye package on the substrate and is resistant to phosphate ester degradation. The formulation includes a pigment or a dye and a thixotropic agent; and in certain embodiments, at least one of: an anti-skinning additive, a synthetic drier, a wetting additive, a gelled viscosity builder additive and a rheological additive.

In contrast to the prior art of <CIT> that is based on a polyurethane (urethane alkyd polymer) resin, the present invention invokes polyester resins that are linear aromatic polyesters, and co-polymers thereof, containing at least <NUM> monomer percent of aromatic polyester subunits. Linear aromatic polyester synthesis and structures are illustratively detailed in <CIT>. In other inventive embodiments, the monomer percent of aromatic polyester subunits is between <NUM> and <NUM> percent. In still other inventive embodiments, a linear aromatic polyester is aliphatically saturated. It is appreciated that a linear aromatic polyester operative herein is either amorphous or crystalline. In still other embodiments, the linear aromatic polyester has a glass transition temperature (Tg) of between <NUM>° C and <NUM>° C, and in still other embodiments, Tg of between <NUM>° C and <NUM>° C. In still other embodiments, the linear aromatic polyester has a hydroxyl number from <NUM> to <NUM>/g KOH/g. The linear aromatic polyester has a molecular weight of between <NUM>,<NUM>/mol and <NUM>,<NUM>/mol.

As used herein, polymer molecular weight is weight average molecular weight (Mw), unless otherwise specified.

Upon dispersion or dissolution of an inventive resin in a solvent along with a colorant package and a thixotropic agent, an inventive formulation is amendable to provision to an end user in the form of a paint to be applied by brush or spray, as well as through inclusion with a marker tube. The construct of such a tube is conventional to the art, as sold under the brand name DYKEM® CROSS CHECK™. The resin is present from <NUM> to <NUM> total weight percent of a formulation and in specific embodiments from <NUM> to <NUM> total weight percent. It has been found that solvent that is a mixture of ketones or esters with a less amount of an Aromatic <NUM>, <NUM>, or <NUM> in a weight ratio of <NUM>-<NUM>:<NUM> a provides for a marking that touch dries in less than <NUM> seconds. The resulting film is noted to be resistant to phosphate ester hydraulic fluids.

A colorant operative in the present invention illustratively includes titanium dioxide particulate, carbon black, iron oxides, phthalocyanine blue, azo dyes, anthraquinone dyes, manganese, phosphors, and combinations thereof. These pigments and dyes are amenable to dissolution or suspension in the solvated linear aromatic resin. A pigment or dye is present from <NUM> to <NUM> total weight percent of a complete formulation for application to a substrate. It is appreciated that while a dye can be operative in amounts as lows as <NUM> total weight percent, particulate pigments require larger quantities to affect coloring. In certain embodiments, the colorant is present from <NUM> to <NUM> total weight percent. It is appreciated that a colorant package in some embodiments includes solvents, surfactants, non-foaming agents, and other conventional additives to facilitate storage and dispersion. Fluorescent or phosphorescent pigments and dyes are preferred as being visible to the unaided normal human eye under a variety of lighting conditions. A variety of such pigments and dyes are available from the DAYGLO Corporation, Cleveland, Ohio, USA. These colors illustratively include pink, yellow, blue, orange, and green.

The linear aromatic polyester resins of the present invention are dissolved or at least dispersed in a solvent. A solvent suitable for dissolution or dispersion of an inventive resin illustratively include halogenated hydrocarbons such as methylene chloride, chloroform, <NUM>,<NUM>-dichloroethane, tetrachloroethane, methylchloroform, <NUM>,<NUM>,<NUM>-trichloroethane; benzene; C<NUM>-C<NUM> aromatics having a methyl group or groups attached to the ring in the ortho, meta, or para positions, naphthalenes; C<NUM> -C<NUM> ketones, such as methyl ethyl ketone, acetone, and diacetone alcohol; cyclic C<NUM>-C<NUM> ethers; (C<NUM>-C<NUM>)-O-(C<NUM>-C<NUM>) ethers; ethylene glycol ethers; diethylene glycol ethers; C<NUM>-C<NUM> alkyl esters of C<NUM>-C<NUM> carboxylic acids, and combinations any of the aforementioned that are miscible. It is appreciated that racemic blends aromatics are operative herein that illustratively include Aromatic <NUM>, Aromatic <NUM>, Aromatic <NUM> or combinations thereof are operative herein. Solvent constitutes a major component by weight of a formulation prior to drying to a hard resin film containing colorant and thus is the remainder after inclusion of various additives to the formulation, yet is almost all removed from a vacuum dried film. Typically, solvent as a single component or mixture of miscible solvents is present from <NUM> to <NUM> total weight percent of a complete formulation for application to a substrate.

It is appreciated that the solvent of an inventive formulation will readily dissolve the machine oil commonly coating many metal parts thus allowing tamper or torque marking to occur with an inventive formulation without a degreasing step in common work settings. An inventive formulation is capable of drying to the touch in between <NUM> and <NUM> minutes and in some embodiments in less than <NUM> minutes or even less than <NUM> minutes so as not to impede repeated handling of the surface.

A thixotropic agent operative in the present invention illustratively includes fumed silica, organoclays, inorganic clays and precipitated silica. Multifunctional alcohols are commonly used to enhance thixotropic properties. The thixotropic agent is present from <NUM> to <NUM> total weight percent of a complete formulation for application to a substrate. To the extent a multifunctional alcohol used, it is typically present from <NUM> to <NUM> weight percent of the thixotropic agent.

Fillers operative in the present invention illustratively include talc, mica, alumina trihydrate, calcium sulfate, calcium carbonate, magnesium sulfate, magnesium carbonate, barium sulfate, microspheres and the like. A filler is present from <NUM> to <NUM> percent of a complete formulation for application to a substrate. In certain embodiments, the filler is present from <NUM> to <NUM> total weight percent.

A siccative additive is provided in some embodiments to regulate the drying speed of the formulation. A siccative additive operative in the present invention illustratively includes a transition metal carboxylate for which medium- to long-chain linear or branched carboxylic acids - most commonly <NUM>-ethyl hexanoic acid or various naphthenic acids are used as ligands, and combinations thereof. Transition metals typically include cobalt, zirconium, and manganese; and a routinely used in the printing industry as drying accelerators. A siccative additive is present from <NUM> to <NUM> percent of a complete formulation for application to a substrate. In certain embodiments, the siccative additive is present from <NUM> to <NUM> total weight percent.

In some inventive formulations particularly well suited for application from a tube having an opening, the formulation is adjusted to not only have storage stability of at least <NUM> month and in some instances more than <NUM> months without appreciable separation, but also to have a viscosity in the range of <NUM>,<NUM> to <NUM>,<NUM> centipoise. The tube selectively sealed with a cap for extruding the formulation as a bead. The bead typically having a width of <NUM> ± <NUM> millimeters (mm). An inventive formulation is summarized in the following Table <NUM>.

The formulation is readily supplied in a marking tube. The marking tube is typically formed of aluminum and includes an opening to define a volume for containing the formulation. To preclude the formulation drying prematurely on the opening, a cap is selectively removable to expose the opening from which the formulation is dispensed as a bead. In this way, a controlled bead width is easily applied to a surface.

The present invention is further illustrated with respect to the following non-limiting examples:.

A linear aromatic polyester resin having a Tg of <NUM>° C and a molecular weight of <NUM>,<NUM> that is amorphous is dissolved to <NUM> total weight percent in a solvent of methyl ethyl ketone (<NUM> total weight percent) and Aromatic <NUM> (<NUM> total weight percent) with <NUM> total weight percent hectorite clay and the remainder being thixotropic particulate. The resulting formulation is packed into in an aluminum tube and crimped using a conventional tube filling system and applied as a bead <NUM> millimeters (mm) in width and a thickness of <NUM> onto substrate panels of glass, mild steel, aluminum, ceramic, porcelain, acrylic, polyethylene, and polyamide without exhibiting sagging. The formulation dried in approximately <NUM> seconds to the touch. After drying overnight, the panels are immersed in SKYDROL® PE-<NUM> hydraulic fluid and found to be unchanged after <NUM> hours.

The formulation of Example <NUM> is modified with inclusion of <NUM> total weight of DAYGLO® pink (Example <NUM>, MC-<NUM>), or yellow (Example <NUM>, MC-<NUM>), blue (Example <NUM>, MC-<NUM>), orange (Example <NUM>, MC-<NUM>), or green (Example <NUM>, MC-<NUM>) fluorescent pigment and the concurrent proportional reduction in the other components of Example <NUM>. The formulation of Examples <NUM>-<NUM> are applied to panels and tested per Example <NUM> with nearly identical results.

A saturated linear aromatic polyester having a Tg of approximately <NUM>° C. , acid number <<NUM> KOH/g, OH number <NUM>/g KOH/g, and a molecular weight of <NUM>,<NUM> is dissolved to <NUM> total weight percent in a solvent of methyl ethyl ketone (<NUM> total weight percent) and Aromatic <NUM> (<NUM> total weight percent) and containing <NUM> total weight percent of the pink fluorescent pigment of Example <NUM> with <NUM> total weight percent hectorite clay and the remainder being thixotropic particulate. The formulation of Example <NUM> is applied to panels and tested per Example <NUM>. The resulting drying markings on the panels withstand between <NUM> and <NUM> hours of immersion in SKYDROL® PE-<NUM> hydraulic fluid without degradation.

Example <NUM> was repeated with the replacement of the resin with an equal amount of saturated linear aromatic polyester having a Tg of approximately <NUM>° C. , acid number <<NUM> KOH/g, OH number ~<NUM>/g KOH/g, and a molecular weight of <NUM>,<NUM>. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of B98 polyvinyl butral (PVB) BUTRA® (Eastman Chemical). The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of SARAN® F310: PVDC vinyl resin. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of ELVACITE® <NUM> Acrylic resin. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of Dow Epoxy <NUM> resin. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of DYNAPOL® (Evonik) S1611 polyester resin. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of Bostik <NUM> polyester resin. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of Toyobo <NUM> polyester resin. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Example <NUM> was repeated with the replacement of the resin with an equal amount of <NUM> polyamide resin (Henkel) resin. The resulting markings remained tacky and soft and were displaced by immersion in SKYDROL® PE-<NUM> for one hour.

Claim 1:
A surface marker resin formulation comprising:
a linear aromatic polyester or a co-polymer thereof containing at least <NUM> monomer percent of aromatic polyester subunits, the said polyester or co-polymer thereof being present in an amount of <NUM> to <NUM> total weight percent of the formulation, wherein said linear aromatic polyester or a co-polymer thereof has a weight average molecular weight of between <NUM>,<NUM> and <NUM>,<NUM>/mol;
a solvent in which said linear aromatic polyester or a co-polymer thereof is dissolved or dispersed;
a colorant package dissolved or dispersed in said solvent,
wherein the formulation further comprises a thixotropic agent present in an amount from <NUM> to <NUM> total weight percent.