An automotive seat assembly is provided with an integrated side impact airbag. The seat assembly comprises a seat cushion and a seat back mounted to the seat cushion. A seat cushion trim cover material covers the seat cushion and a seat back trim a cover material covers the seat back. The seat assembly is characterized by a tear seam integrally formed within a bolster section of the seat back trim cover material. The tear seam defines a frangible line of weakness within the trim cover material wherein the airbag will tear through the tear seam when the airbag is deployed and inflated to a position outside of the seat assembly. The subject invention also includes a manufacturing apparatus for forming the tear seam in the trim cover material. The apparatus comprises a template (48) supporting the trim cover material (28). A C-shaped raised ridge (50) extends upwardly from the template to abut the inside surface of the trim cover material (28). A welder (52) is disposed adjacent the outside surface of the trim cover material (28) such that the trim cover material is wedged between the template (48) and the welder (52). The welder is aligned with the raised ridge to form the tear seam within the trim cover material.

The subject invention relates to automotive seat assemblies having integral airbags. More precisely, the subject invention relates to the specific characteristics of the seat assembly which ensure a complete and full deployment of the airbag.
Government and automobile industry researches are continuously looking at ways to make can safer. Airbags are frequently installed within the dash board, armrest, and steering wheel of many vehicles to enhance the safety of the vehicle. European Patent No. 0 749 872 illustrates one such example of an airbag in a dash board and European Patent No. 0 733 518 illustrates an example of an airbag disposed within an armrest. Both of these designs form a weakened deployment seam within the plastic material forming the dashboard and armrest. The deployment seam is typically formed on both an inside and outside of the material. Once deficiency with forming the seam on both sides of the material is that this creates a noticeable cut or depression in the dashboard and armrest. As disclosed in the European ""872 patent, the seams are typically formed by inserting a welder into the material itself. This method of forming the seams can significantly reduce the operating life of the welder.
The frequent use of airbags has lead to the thought of installing airbags in other locations within the vehicle. One prominent direction is toward installing airbags directly within a vehicle seat. Primarily, the airbags are installed within a side bolster of the seat such that they provide better head, neck and side protection for the occupant. These airbags are commonly called side impact airbags. Side impact airbags operate much the same fashion as frontal airbags. A crash sensor is often located in a B-pillar of the vehicle which detects a serious impact occurring perpendicular to the side of the vehicle. As appreciated, there is little clearance between the passenger and the outside of the vehicle door. Hence, side impact airbags must inflate much faster than frontal airbags.
The side impact airbags are frequently concealed within the seat by a trim cover material. The trim cover material is typically made up of multiple smaller pieces of material which are sewn together. The airbags break through the sewn seams during deployment. One of the major concerns with seat integrated side impact airbags is achieving successful deployment of the airbag through the proper seam in the trim cover each and every time.
One frequent difficulty associated with side impact airbag deployment is that the airbag deploys through the seam at a wrong angle. This limits the amount of protection available to the passenger and may even injure the passenger. Another problem occurs when the airbag exits through the wrong seam such as through the front or the back of the seat. This may also cause additional injury and may not adequately protect the passenger. In addition, the airbag may not exit the seat at all. In this situation, the airbag balloons within the trim cover material and never breaks the seam.
The deployment problems occur for a number of reasons. The trim cover material typically has an elasticity which works against the braking force the airbag. In addition the trim cover material is secured to a foam pad by either thin wire rods, hog rings, a hook and loop fastener, or a bonding process. None of these manufacturing methods are strong enough to hold the trim cover material to the foam pad when the airbag is being deployed. The airbag will always follow the path of least resistance and may detach the trim cover from the foam pad such that the airbag will wander within the trim cover itself.
One solution contemplated by the prior art is to sew straps into the trim cover and tie the straps to the seat back frame to hold the trim cover material to the foam pad and seat back frame. This solution, however, has a number of deficiencies. Some of the deficiencies are that the straps may be difficult to secure to the frame, it would be difficult to ensure proper attachment and proper taughtness, and the straps may provide unpredictable deployment characteristics.
Accordingly, it is desirable to create a weakened deployment seam within the trim cover material that is the weakest point in the trim cover such that the airbag can predictably break through the trim cover material and fully deploy. The deployment seam must also be strong enough to maintain its integrity during normal use of the seat.
Some solutions have been contemplated by the prior art such as laser cutting and changing the parameters of the stitching. The laser cutting is unreliable in that the particular depth needed is difficult to uniformly achieve. The laser cutting is also time consuming and expensive. Changing the parameters of the stitching along the area of deployment is also difficult to control and expensive to implement.
Ultrasonic welding is a means of fusing pieces of material together and for forming cuts or grooves within both sides of a material. One such example of ultrasonic welding is shown in French Patent No. 2 665 683 which ultrasonically welds thin plastic bags. The known ultrasonic welders, however, have not been modified and thus are not capable of forming seams within relatively thick multilayered pieces of material such as trim cover materials.
An automotive seat assembly is provided with an integrated airbag. The seat assembly comprises a seat cushion and a seat back mounted to the seat cushion. A seat cushion trim cover material covers the seat cushion and a seat back trim cover material covers the seat back. The seat assembly is characterized by a tear seam integrally formed within at least one of the trim cover materials to define a frangible line of weakness within the trim material wherein the airbag will tear trough the tear seam when the airbag is deployed and inflated to a position outside of the seat assembly.
Accordingly, the subject invention provides a weakened tear seam within the trim cover material which is the weakest point in the trim cover such that the airbag can predictably and effectively break through the trim cover material and fully deploy. The tear seam is also strong enough to maintain its integrity during normal use of the seat assembly.

Automotive seat assembly having an integral tear seam


A thermo-transfer ribbon with a carrier, a first thermo-transferable layer formed on one side of the carrier and a second thermo-transferable layer formed on the first thermo-transferable layer, wherein (i) the first thermo-transferable layer contains a luminescent pigment, wax(es) having a melting point of approximately 70 to 110xc2x0 C. and approximately 1-22% by weight of a polymer wax plasticizer having a glass temperature Tg of xe2x88x9230 to +70xc2x0 C., (ii) the second thermo-transferable layer contains a non-luminescent pigment, a wax compatible polymer binder and approximately 5 to 30% by weight of wax and/or wax-like substance, (iii) the second thermo-transferable layer has a melting enthalpy DH of approximately 10 to 80 J/g and (iv) in the remission spectrum of the non-luminescent pigment in the wave length range of the light emitted by the luminescent pigment there is a remission maximum or an ascending flank of remission. The thermo-transfer ribbon furnishes print having high optical density without adversely affecting the luminescent power of the luminescent pigment. It is particularly suitable for high speed printing with edge-type print heads.

The present invention relates to a thermo-transfer ribbon for luminescent letters or codings.
Modern sorting machines, as employed when sorting a multitude of objects, such as for example letters, react to luminescent coding which is not necessarily visible to the human eye. To that end, the pieces to be sorted are furnished, prior to the sorting process, with symbols which contain a luminescent substance. In growing measure, thermo-transfer (color) ribbons are used for said purpose, which have a layer of thermo-transfer color with a therein contained luminescent pigment. The luminescent transfer color, which is transferred to the substrate surface, is very thin and transparent for visual examination.
Luminescent colors have the property of absorbing ultraviolet light and visible light in the blue portion of the spectrum and to again radiate said absorbed portion at the lower end of the spectrum. From among the great number of organic compounds, which radiate visible light under the influence of short-wave rays, only such substances are suitable as luminescent pigments or luminogens which distinguish themselves in solid, non-dissolved state by intensive fluorescence. Those luminescent pigments which fluoresce in colors under day light, and which are employed as daylight fluorescent pigments, command the greatest technical interest. Soluble pigments of this type are for example rhodamine, eosine, brilliant sulfoflaven FF and the highly yellow-green fluorescent pyranine, also color pigments, for example 2,2-dihydroxy-alpha-naphthaldiazine and anthrapyrimidine.
Inasmuch as the pigments are organic in nature, it is necessary to dissolve them in an organic medium or carrier. Mostly tinted carrier substances are employed, for example pulverized polymerisates which are tinted with soluble pigments or finely distributed pigments. The type of material which corresponds to the requirements of a carrier or a matrix for the pigments is a transparent organic resin. By reacting acid polyester resins with basic pigments or by pulverizing solidified color substance solutions, one likewise obtains tinted carrier substances. Urea formaldehyde resins, acrylic resins and melamine resins are also used as carriers, onto which the pigments may be lacquered. Daylight fluorescent pigments are, in fact, organic plastic particles, which are tinted with fluorescent color substances. The physical structure of the pigment particles is mostly amorphous.
When luminescent material is precipitated on the surface of white paper, the whiteness of the paper serves as light reflector. The major portion of the incident light is reflected back by the paper through the imprinted luminescent material. The reflected light perceived by the observer contains both incident light as well as luminescent light.
If the luminescent material is transferred to the surface of a dark colored paper, a portion of the incident light, which has passed the luminescent layer, is absorbed by the paper. The amount of the light available from reflection is decreased. In addition, that percentage of light emitted by the luminescent color layer is being absorbed, which is radiated in the direction of the paper surface.
In order to compensate for the differences in intensity of luminescence, which are attributable to the type of carrier, DE-OS 30 42 526 proposes a fluorescent print ribbon, which is characterized by addition of a blocking material to the fluorescent pigment material, in order to block absorption of the incident light in the medium onto which the pigment and the blocking coating are transferred during printing. The blocking material is preferred as a second coating above the pigment coating. Both coatings are transferred in reverse order onto the substrate during the printing process. The blocking material contains reflecting metal particles or mother-of-pearl-type pigments.
DE-AS 12 22 725 discloses a transfer material for luminescent letters with a coating carrier of paper or foil with a luminescent color layer arranged thereon, whereby a pigmented, light-radiation reflecting coating is placed over the luminescent color layer, which participates in the writing process. The cover layer preferably contains titanium white and/or pressure-ground aluminum powder.
The known suggestions are aimed at avoiding absorption, in the substrate, of incident light passing through the luminescent layer, so that this portion is being reflected and once more passes through the luminescent color layer, in order to thus increase the overall excitation yield. It is, hereby, of drawback that the luminescent light perceived by the observer is always mixed with the reflected portion of incident light. The luminescent print-outs therefore always appear pale, i.e. they have low optical density.
If attempts are made to increase the optical density of the print-outs by adding a non-luminescent pigment to the layer of luminescent pigment, one notes that with an addition of extraneous pigments of more than 1%, fluorescence quality is significantly affected. With increasing addition amounts, there is growing impairment of the brilliance of the fluorescent pigments, the fluorescence power and color purity due to occurring interferences. Still higher addition amounts lead to almost total extinction of fluorescence. From the aspect of fluorescent output, an additional amount of 1% or less, however, would, only insignificantly increase the optical density.
The above described thermo-color ribbons are finding increasing entry in high speed printers, specifically in industry, whereby print heads are being employed of the so-called xe2x80x9cReal-Edgexe2x80x9d or xe2x80x9cCornerxe2x80x9d type. In these print heads a series of targetable heating points (dots) is arranged on a ceramic substrate, close to the edge or directly on the rim. The benefit of edge-type heads lies in shorter cooling-down times and correspondingly higher registration frequencies. Printing speeds of from 3 to 12xe2x80x3 per second can be achieved with them. Prints obtained with high-speed printing are subject to special requirements with respect to print quality, i.e. excellent edge definition, dissolution and optical density. A specific application field is the imprinting of paper and plastic labels. With respect to the latter, high scratch resistance of prints is desirable.
The thermo-transfer ribbons for luminescent codes provided thus far by the state of the art do not satisfy the addressed requirements to the desired extent. The invention is therefore based on the object of providing a thermo-transfer color ribbon for luminescent codes, whereby print-outs of high optical density could be obtained without affecting the luminescence output of the luminescent pigment and irrespective of substrate to be imprinted, including satisfactory print quality at high printing speeds. The luminescent symbols transferred during the printing process shall have good adhesion and good scratch resistance, specifically on paper and plastic labels.
According to the invention, this object is solved by a thermo-transfer ribbon with a carrier, a first thermo-transferable layer formed on one side of the carrier and a second thermo-transferable layer formed on the first thermo-transferable layer, whereby (i) the first thermo-transferable layer contains luminescent pigments, wax(es) having a melting point from approximately 70 to 110xc2x0 C. and approximately 1 to 22% by weight of a polymer wax plasticizer with a glass temperature Tg of xe2x88x9230 to +70xc2x0 C., (ii) the second thermo-transferable layer contains a non-luminescent pigment, a wax-compatible polymer binding agent and approximately 5 to 30% by weight of wax and/or wax-like substance, (iii) the second thermo-transferable layer has a melting enthalpy DH of approximately 10 to 80 J/g and (iv) there is, in the remission spectrum of the non-luminescent pigment in the wave length range of the light emitted by the luminescent pigment, a remission maximum or an ascending flank of remission.
In preferred specific embodiments, the second thermo-transferable layer contains approximately 5 to 40% by weight, specifically approximately 10 to 20% by weight of filler substances.
The non-luminescent pigment is a pigment whose remission is highly wave-dependent. The color impression of a non-luminescent pigment is produced as result of selective reflection of several segments of the visible white light spectrum. The non-reflected part is absorbed and converted into heat. An orange-red color reflects, for example, the orange-red part of light and absorbs all other colors of the spectrum. Good, non-luminescent pigments are capable of reflecting approximately 90% of the corresponding portion of the spectrum. White pigments, however, show non-selective high reflection over the entire visible spectrum.
The non-luminescent pigment to be employed according to the invention reflects only the light emitted by the luminescent pigment and the wave length portion of the not absorbed incident light, which lies at or near the (longest-wave) emission bands of the luminescent pigment. The obtained print-outs thus show substantially more contrast and improved optical density. Selection of the non-luminescent pigment permits, in addition, that the color shade of the print-out is varied within certain limits, without loss of brilliance, because of interference between the emitted light and the light remitted by the non-luminescent pigment.
For purposes of the invention, it is preferred that the luminescent pigment is a daylight fluorescent pigment and the non-luminescent pigment is a color pigment. The daylight fluorescent pigments are commercially available under the brand names Lumogens (BASF), Day-Glo(copyright) Colors, Goldfire-Colors, Fluorzink or Brillink-Glow Color. In view of targeted use in postage meter printers, the daylight fluorescent pigment preferably emits in the wave length range of orange to red, i.e. at approximately 580 to 620 nm (with an excitation energy of 254 nm). The preferred color pigment is hereby a red pigment, whereby this term is to be understood in its most comprehensive meaning.
In high-speed print, the thermal print head dwells only a very short time at a given location of the thermo-transfer ribbon. Since, on the other side, the print head output is limited, there is only very little energy available for softening the thermo-transferable layer. It was then discovered that in order to attain high print speeds, a thermo-transferable layer with low melting enthalpy can be employed to advantage. It has been shown, however, that layer compositions having low melting enthalpy in melted state show high adhesion to carrier materials, so that the result would be inadequate transfer to the accepting substrate during the printing process. The invention solves this problem by special layer composition of the first and second thermo-transferable layer.
The waxes employed in the first thermo-transferable layer follow the standard definitions for wax, with limitation of melting point to approximately 70 to 110xc2x0 C. In the most comprehensive meaning of the term, this involves material which is solid to brittle hard, coarsely to finely crystalline, transparent to opaque, but not glass-like, which melts above 70xc2x0 C., but is just slightly above the melting point relatively low viscous and not stringy. Waxes of this type can be categorized into hydrocarbon waxes (alkanes without functional groups) and waxes from long-chain organic compounds with functional groups (mainly ester and acid waxes). Among the hydrocarbon waxes are, aside from mineral wax, the solid hydrocarbons produced from crude oil and tar and also synthetic paraffins. Among the waxes with functional groups are all vegetable waxes including chemically modified waxes. Ester waxes consisting essentially of esters, which are formed from linear carbonic acid with approximately 18 to 34 C-atoms and approximately equally long linear alcohols. High percentages of free carbonic acid are represented in acid waxes. Waxes with functional groups are preferred. To be named among these are particularly ester waxes, for example on basis of mineral wax, partially saponified ester waxes, acid waxes and oxidized and esterified synthetic waxes. Named among the particularly preferred ester waxes are vegetable waxes, such as carnauba wax and candellila wax, including high-melting, closely-cut paraffins. Particularly preferred, within the scope of the invention, are waxes having a melting point from 70 to 105xc2x0 C. Particularly preferred are the following: Carnauba wax, LG-wax BASF and Hoechst Wax E. Wax(es) preferably amount to 40-80% by weight of the first thermo-transferable layer.
The first thermo-transferable layer also contains approximately 1 to 22% by weight, preferably approximately 2 to 20% by weight and specifically approximately 4 to 10% by weight of polymer wax plasticizer. Said plasticizer causes the particularly prefered hard waxes, specifically in the form of ester waxes and high-melting closely cut paraffins to be plasticized and thus lose their brittleness and tendency to xe2x80x9csplinterxe2x80x9d. They ensure good anchoring or adhesion of the separation layer to the carrier material. Ester waxes are very hard or brittle waxes, i.e. they can be pulverized in cold state. If these are mixed with the named polymer wax plasticizers, elastic products are created which can hardly be pulverized. The specified amount of polymer wax plasticizer is critical. Higher than specified quantities should be avoided, because otherwise there is insufficient release effect in relation to the carrier. Too low a quantity of polymer wax plasticizer results, among others, in that the brittle wax is inadequately plasticized and the layer shows no uniform separation behavior or leads to an inhomogeneous image, primarily in coherent color areas.
To be considered as wax plasticizers are polyesters, co-polyesters, polyvinylacetate, polystyroles with a glass temperature Tg of xe2x88x9230 to +70xc2x0 C., preferably xe2x88x9220 to +10xc2x0 C. Preferred among these are polyesters and co-polyesters. Preferably this involves linear saturated polyesters or co-polyesters with an average molecular weight of 1500 to 18000. The first thermotransferable layer usually has a melting enthalpy DH of approximately 150 to 210 J/g.
The second thermo-transferable layer has a melting enthalpy DH of approximately 10 to 80, specifically approximately 15 to 50 J/g. According to the state of the art, thermo-transfer color layers usually have a melting enthalpy DH in excess of 130 to 220 J/g. The term xe2x80x9cMelting Enthalpy DHxe2x80x9d signifies the amount of endothermal energy which is represented by the peak area which is enclosed in the thermal flow-temperature curve and the base line when taking DSC measurements in a temperature interval of 25 to 120xc2x0 C. During the specified temperature interval, the layer composition of the second thermo-transferable layer need not necessarily melt completely, which is regularly the case if the layer contains dispersed insoluble constituents, like fillers.
Of significance is only that the composition of the layer in the specified temperature interval has at least one phase transfer during which it passes from solid state to a relatively low viscous state, and that said phase transfer generates a peak in the DSC calorigram which corresponds to the specified energy amount. When several peaks occur, adjustment must be made to the sum of the peak areas. In order to obtain sufficiently low melting enthalpy, particular importance must be assigned to the selection of the binding agent. The binding agent of the second thermo-transferable layer must, in addition, be wax-compatible so that the layer has sufficient adhesion relative to the first thermo-transferable layer. The term xe2x80x9cwax-compatiblexe2x80x9d in this context means that this polymer is compatible with a liquid wax and during cooling of a solution or dispersion of the polymer in wax there will be no phase separation. Wax-compatible polymers according to the meaning of the invention distinguish themselves in that they are meltable below approximately 100xc2x0 C. They are sticky in molten state. Suitable polymers are for example ethylene-vinylacetate-copolymers (EVA), ethylene-acrylic acid co-polymers, polyamides and ionomer resins. Preferred among these are ethylene acrylic acid co-polymers and EVA, specifically a polymer having a vinylacetate contentsxe2x89xa7approx. 25% by weight. Particularly appropriate are types with at least approximately 33 or 40% by weight of vinylacetate.
The second thermo-transferable layer contains, in addition, approximately 5 to 30% by weight, specifically approximately 15 to 25% by weight of waxes and/or wax-like substances. The addition of waxes and/or wax-similar substances prevents conglutination of the ribbon in rolled-up state or adhesion of ribbon at the location of the accepting substrate where no symbol is to be transferred. Higher than specified amounts of wax must be avoided because the high melting enthalpy of the wax would result in too high a melting enthalpy of the entire formulation. It is true that a low addition of wax leads to low melting enthalpy, but will not prevent sticking to the degree desired. Suitable waxes for the second thermo-transferable layer are: close-cut paraffin waxes, ester waxes, acid waxes, micro-waxes and modified micro-waxes. Mineral waxes are not preferred. Close-cut paraffin waxes are particularly preferred. The enumerated waxes distinguish themselves in that softening point and melting point lie close together. During heating, at least 80% of the material should become fusible within a temperature interval of 10xc2x0 C. The melting point of the waxes in the second thermo-transferable layer preferably lies at approximately 70 to 105xc2x0 C.
The second thermo-transferable layer preferably receives, in addition, also filler substances (extenders) such as for example aluminum silicate, aluminum oxide, silica, talcum, calcium-carbonate, aluminum hydroxide, zinc oxide, silicic acid, kaolin, titanium dioxide etc. The extenders lighten the color (transparent layers) and, at the same time, the xe2x80x9csticking behaviorxe2x80x9d of the ribbon is favorably influenced.
Many other added substances may be incorporated into the second thermo-transferable layer. The layer of the thermo-transfer color preferably contains one or several resins having a melting point from 80 to 150xc2x0 C. Suitable resins are for example: KW-resins, terpene phenol resins, modified colophony resins, coumarone-indene resins, maleic resins, alkyde resins, phenol resins, polyester resins, polyamide resins and/or phthalate resins. Among these, KW resins and poly-terpene resins are particularly preferred. The ratio of wax-compatible polymer to resin in the thermo-transfer color is preferably between 70:30 to 90:10 (weight/weight).
The viscosity of the second thermo-transferable layer must be sufficiently low, so that the color can be given off quickly and dot-accurately. It preferably has a viscosity of approximately 500 to 3000 mPasxc2x7s, measured at 140xc2x0 C. in a Brookfield-Rotation-Viscosimeter. A range of 600 to 1500 mPaxc2x7s. is particularly desirable.
The polymer binding agent employed in the second thermo-ransferable layer is amorphous or in part crystalline and requires little energy for the melting process.
Following the printing process, separation occurs of the thermo-transfer ribbon from the acceptor, as long as the layer is still xe2x80x9cliquidxe2x80x9d, in other words, is still in molten or softened state. This circumstance permits utilization of polymer-resin-bound colors, which, in turn ensure high sharpness of edge, good resolution and optical density. This is primarily of importance with real-edge print heads. The plastic-bound color layer warrants excellent scratch resistance of transferred print symbols on paper as well as on plastic labels.
The thicknesses of the thermo-ransferable layers are not critical. The first thermo-transferable layer preferably has a thickness of approximately 0.4 to 4 xcexcm, specifically approximately 1 to 2 xcexcm. Thickness of the second thermo-transferable layer preferably measures approximately 1 to 5 xcexcm, specifically approximately 1 to 3 xcexcm.
The type of substrate of the thermo-transfer ribbon according to the invention is likewise not crucial. Preferably it involves polyethylene-terephthalate foil (PETP) or condenser papers. Selection parameters are highest possible stress/strain values and thermal stability with low foil thicknesses. The PETP foils are obtainable in a thickness down to approximately 2.5 xcexcm, condenser papers down to approximately 6 xcexcm.
A beneficial improvement of the concept according to the inventionxe2x80x94specifically with respect to achieving excellent printxe2x80x94is based on the teaching of EP-B-O 133 638. Accordingly, a layer is formed on the reverse side of the carrier, consisting of a wax or a wax-type material, specifically with a thickness of not more than 1 xcexcm and particularly preferred in form of a molecularly developed layer up to 0.01 xcexcmxe2x80x94with coating material in this case preferably consisting of paraffin, silicone, mineral waxes, specifically carnauba wax, bees wax, ozocerite and paraffin wax or synthetic waxes, specifically acid waxes, ester waxes, partially saponified ester waxes and polyethylene waxes, glycoles or poly-glycoles and/or tensides.
In certain instances it may be of benefit to incorporate additives that improve the properties of the ribbon. In such case a person skilled in the art will select, within the scope of expert considerations, that particular additive with which he intends to produce a certain effect.
The thermo-transfer ribbon can be produced in many ways using conventional application methods. This can be done, for example, by spraying or imprinting a solution under dispersion, either with water or an organic solvent as dispersion medium or a solvent, by application from the melt, which applies particularly with respect to the wax-bound, first thermo-transferable layer, or also by application by means of a wiper in form of a watery suspension with a finely therein distributed coating material. For application of the release layer as well as the color layer, coating methods, such as reverse roll and/or engraving coating have proven particularly beneficial.
With respect to the practical realization of the present invention, the following basic conditions may be stated regarding application quantities of the individual layers:
Onto a carrier foil, specifically a polyester foil having a thickness of approximately 2 to 8 xcexcm, specifically a thickness of approximately 4 to 5 xcexcm, are applied, in succession: Coating mass for forming the first thermo-ransferable layer 0.5 to 4 g/m2, preferably approximately 0.5 to 2 g/m2, and coating mass for forming the second thermo-ransferable layer 1 to 5 g/m2, preferably approximately 1 to 2 g/m2. If required, an above mentioned reverse side coating is formed on the reverse side of the carrier having a thickness of approximately 0.01 to 0.2 g/m2, specifically of approximately 0.05 to 0.1 g/m2.
The thermo-transfer ribbon according to the invention is beneficially utilized in a corner-edge type printer, specifically in postage metering machines. It comes as a surprise that all kinds of paper, i.e. smooth as well as rough papers, can be used, providing excellent print quality. The layer of the second thermo-transfer paper seems to act hereby as xe2x80x9ctop coatxe2x80x9d equalizing unevenness of the surface.

Thermo-transfer ribbon for luminescent letters


An apparatus for modeling a skeletal structure before and after a surgical procedure is performed on the structure. The apparatus comprises a base, the base including a generally planar surface, at least one bone member coupled to the base, the bone member representing a bone involved in the surgical procedure, and at least one bone portion movably coupled to the bone member, the bone portion representing a part of the bone involved in the surgical procedure that is repositioned in the surgical procedure from a preoperative position to a postoperative position. The bone portion may be selectively moved between a preoperative position, representing the position of the part of the bone before the surgical procedure is performed, and a postoperative position, representing the position of the part of the bone after the surgical procedure is performed. The bone member may be coupled to the base generally parallel to the surface of the base.

The present invention relates to an apparatus for modeling a skeletal structure before and after a surgical procedure is performed on the structure. More particularly, it relates to a tool that may be used to model the structure and mechanics of a skeletal joint both before and after an osteotomy is performed on a bone of the joint.
Many medical conditions involving the skeletal system may be remedied by the performance of an osteotomy technique, or the surgical division or sectioning of bone. As an example, a veterinary surgeon may perform a technique known as a tibial plateau leveling osteotomy to remedy problems caused by a weakened or ruptured cranial cruciate ligament in the leg of a dog. When the cranial cruciate ligament of a dog is damaged, the tibia may move forward relative to the femur when the leg is loaded. This forward motion, known as tibial thrust, may cause more severe injury to the dog""s leg in the form of soft tissue (medial meniscus) impingement. The forward motion can occur because the tibial plateau, or the region of the proximal end of the tibia that contacts the femur, meets the femur at a nonperpendicular angle relative to the direction of the force the tibia exerts against the femur when the leg is loaded. The tibial plateau leveling osteotomy procedure is used to change the angle at which the tibial plateau contacts the femur to be more perpendicular to the direction of this force. In the procedure, a curvilinear cut is made in the proximal region of the tibia to free a portion of the tibia, including the tibial plateau region, from the rest of the bone. This portion may then be rotated along the curvilinear cut to change the angle at which the tibial plateau meets the femur. After the angle is changed to the desired angle, the bone portion is fixed to the rest of the tibia by conventional means.
Before performing an osteotomy procedure, a physician or veterinarian generally must explain the various aspects of the procedure to the patient or pet owner. For example, the doctor must explain the mechanics of the injured joint, and why the osteotomy is necessary to change the joint structure to fix the joint. The doctor must also explain how the osteotomy is performed, and why the joint will perform better after the surgery. Several methods may be used to convey this information to the patient. First, the doctor may simply talk to the patient. However, many people lack the physiological knowledge or training necessary to understand a discussion of bone mechanics and surgeries, even if the doctor describes the procedure in lay terms. Furthermore, a doctor often needs to use a relatively large quantity of unwieldy language to explain even simple procedures. Thus, a doctor who verbally describes a procedure runs the risk that a patient or pet owner will not understand all aspects of the procedure.
A doctor may also use some sort of visual aid to show the patient or pet owner how the procedure is to be performed. For example, a doctor may make or use two-dimensional illustrations of the joint before and after the surgery is performed to illustrate the procedure. Verbal descriptions combined with illustrations are superior to verbal descriptions alone for several reasons. First, a doctor may convey with a single illustration a complex idea that may be difficult to describe verbally. Also, the doctor may point to the illustration while describing a particular aspect of the joint or surgery to show the patient exactly what is being discussed. If the doctor wants to describe changes in the structure or performance of the joint caused by the surgery, the doctor may use separate illustrations to show the joint structure and mechanics before and after each step in the surgery. Though this method may make the description of the surgery somewhat easier for the patient to understand, it still presents difficulties. Most significantly, it is difficult to represent movement with illustrations. Separate illustrations may show the position of a bone before and after a movement, but the illustrations themselves do not represent the actual movement of the bone between the two positions. Thus, even with the use of two-dimensional illustrations, it remains difficult to explain in a simple manner exactly how the changes in bone structure alter the joint mechanics.
Rather than using two-dimensional illustrations to explain a surgical procedure, a doctor may also use a lifelike, three-dimensional skeletal model as a visual aid. Such models allow the motion of the joint to be demonstrated. However, due to the complexity of bone shapes and joint structures, a lay person may not be able to see subtle features in skeletal structure in these models. As an example, a lay person may have difficulty perceiving the angle at which the tibia meets the femur in a canine knee joint if shown a three-dimensional skeletal model of the joint. Also, these models may be fragile and difficult to transport. Thus, it would be desirable to have a simple apparatus or tool for illustrating the movement of a bone fragment during an osteotomy procedure, and for modeling the mechanics of a joint involved in the procedure both before and after the procedure.
One aspect of the present invention provides an apparatus for modeling a skeletal structure before and after a surgical procedure is performed on the structure. The apparatus comprises a base, the base including a generally planar surface, at least one bone member coupled to the base, the bone member representing a bone involved in the surgical procedure, and at least one bone portion movably coupled to the bone member, the bone portion representing a part of the bone involved in the surgical procedure that is repositioned in the surgical procedure from a preoperative position to a postoperative position. The bone portion may be selectively moved between a preoperative position, representing the position of the part of the bone before the surgical procedure is performed, and a postoperative position representing the position of the part of the bone after the surgical procedure is performed.
Another aspect of the present invention provides a tool for representing the mechanics of a skeletal joint before and after an osteotomy is performed on a bone of the joint. The tool comprises a base, the base including a generally planar surface, a first bone member coupled to the base substantially parallel to the base, the first bone member representing a first bone involved in the surgical procedure, and a second bone member movably coupled to the base substantially parallel to the base. The second bone member has opposing ends and represents a second bone involved in the surgical procedure. The second bone member is coupled to the first bone member such that one end of the second bone member is in movable contact with the first bone member to simulate the skeletal joint. The tool also includes a bone portion interposed between the first and second bone members, the bone portion representing a portion of one of the first and second bone members that is repositioned in the surgical procedure. The bone portion is movably coupled to one of the first and second bone members such that the bone portion may be selectively moved between a preoperative position, representing the position of the portion before the surgical procedure is performed, and a postoperative position, representing the position of the portion after the surgical procedure is performed. Movement of the joint before the performance of the surgical procedure may be represented by placing the bone portion in the preoperative position and moving the second bone member with respect to the base, and movement of the joint after the performance of the surgical procedure may be represented by placing the bone portion in the postoperative position and moving the second bone member with respect to the base.
Yet another aspect of the present invention provides a model for demonstrating tibial thrust in a canine knee joint before and after a tibial plateau leveling osteotomy procedure. The model comprises a base, including a generally planar surface, a femur member coupled to base, a foot member including an ankle portion and a heel portion, the foot member movably coupled to base at the heel portion, and a tibia member having opposing ends, the tibia member including a tibial plateau portion movably coupled to tibia member at one end of the tibia member. The tibia member extends between the foot member and the femur member such that the tibia member contacts the femur member at the tibial plateau portion to simulate a knee joint, and the tibia member is pivotally coupled to the ankle portion of the foot member at the other end to simulate an ankle joint. The tibial plateau portion may be moved between at least one preoperative position, wherein the angle of the tibial plateau portion relative to the femur member permits the tibial plateau portion to move in a forward direction relative to the femur member when the foot member is urged toward the tibia member, and at least one postoperative position, wherein the angle of the tibial plateau portion relative to the femur member prevents the tibial plateau portion from moving relative to the femur member when the foot member is urged toward the tibia member.

Apparatus for demonstrating a skeletal surgical technique


A clamping assembly to hold a woodworking knife in place in a woodworking machine. The clamping assembly comprises a clamping component comprising a body and an actuator. The body has three discrete contact positions distributed thereon: 1) a fulcrum located generally at one end, 2) a knife abutting portion located generally at the other end, and 3) a bearing surface located elsewhere. The actuator is for applying a clamping force to the body along a clamping axis located intermediate of the knife abutting portion and the fulcrum. The fulcrum is a surface having a normal that is at an angle to the clamping axis. The bearing surface is a surface wherein a line normal to the bearing surface intersects the line normal to the fulcrum at a position outside of the clamping component at a location farther askew of the clamping axis than the fulcrum.

Many forms of woodworking machines are in use in the forest industry. Some are designed to convert solid wood into a plurality of wood chips for the production of chemical or mechanical pulp. Others are directed to the transformation of wood into chips, veneer, and/or shavings for the production of waferboard, oriented strand board, plywood, lumber, or other such wood products.
Common to such machines is the presence of wood-working knives. The knives can be mounted in various arrangements within the machine to act as required upon the wood being processed. Typically, this involves the mounting of one or more knives on a body of conical, cylindrical, or disc form that is rotated under mechanical or electrical power to cause the knives to act upon the wood in an appropriate fashion. These machines further comprise the means necessary to orient and manipulate the wood against the action of the rotating knives.
With some machines, more than one rotating body may be required to transform the wood in the manner desired. Additionally, with some machine designs, the knives may be maintained in a stationary body while the wood is rotated or otherwise maneuvered against the knives so as to achieve the desired cutting action. What is common with the different arrangements is that the knives are secured to some form of foundation body, or base member, which may be either rotating or stationary, and the knives are brought into relative contact with the wood according to the orientation required to achieve the desired end result.
Common to the aforementioned is that the action of the knives against the wood subjects the knives to considerable cutting forces. The machines must therefore be designed so as to secure the woodworking knives to the base member in a manner to withstand these cutting loads. Since the repeated action of the knives against the wood also results in wear, the machines must also be designed so as to allow for the periodic replacement of the knives. Further, since wood can contain foreign material, such as rock or steel which can be present within the wood itself or embedded or frozen to its exterior, the machine must also be designed so as to allow repairs to be effected in the event of damage to the knives, or other associated machine components.
The most typical means utilized to accomplish the above is to mount the knives in a knife clamping apparatus affixed to the base member. This knife clamping apparatus, often referred to as a knife clamping 'assembly', serves as an intermediate device for securing the knives within the machine. It is generally sized and shaped so as to secure the knives against the cutting forces, allow for their efficient replacement as required, and is typically constructed so as to be mounted to the base member in a fashion that allows for its replacement in the event of damage.
The demands on the clamping assembly are not trivial. Foremost, the clamping assembly must be constructed so that the knives can be retained in their position under the action of the cutting forces. Such cutting forces are typically high in magnitude, extremely episodic, and are usually varied in direction. The clamping assembly must resist deformation, avoid fatigue, and resist breakage when subjected to the stresses associated with these loads. Additionally, the knife clamping assembly must be constructed so as to be of sufficient rigidity so as to minimize deflections such that the knives are not excessively displaced from their proper position within the machine during operation. This latter requirement is important in most woodworking applications where the knife edge must have an accurate location with respect to the wood being processed or other machine components.
The clamping assembly must also be designed so as to allow for the rapid, reliable, and accurate replacement of the knives. Specifically, the apparatus must allow for the knives to be easily removed, the clamping assembly cleaned of any wood debris (flakes, chips, sap, etc.), and replacement knives installed in a repeatable and precise fashion. To achieve this end, the individual components that comprise the clamping assembly should be of a design that permits for a high degree of precision in manufacturing.
Reliability is also of prime importance. In particular, the means employed to clamp and unclamp the knives must be such that a predictable and acceptable mechanical joint is obtained under all circumstances. These means typically comprise some form of actuator of a mechanical or hydraulic nature that can allow the assembly to be opened and closed in a controlled and predictable fashion in order that the knives are properly secured at all times. This actuator, with which the workers must interact to accomplish the changes, should be readily accessible and easy to use.
Since woodworking machines of the type herein described typically operate in a production environment, the design of the clamping assembly must also be such that it is tolerant of the variations that occur under such conditions. This can involve cumbersome working situations where workers need to reach around components of the machine to effectuate a knife change, or limitations in time available between production periods to attend to all aspects of the work in a detailed and thorough fashion. The knife assembly must furthermore exhibit a high degree of fault tolerance so as minor amounts of damage cannot jeopardize the function of the clamping assembly. Such minor damage can easily go unnoticed in a production environment.
To achieve proper integration with the remainder of the machine, the knife clamping assembly must furthermore be of a structure that is compatible with the base member. Such bodies, with their varied forms, impose various geometrical and functional constraints. Foremost it must be sized and shaped to provide for reliable and stable mounting within the base member. Additionally, it must be affixed in a manner that permits for the replacement of components in the event of damage.
The requirements of many modern day machines impose additional demands on the knife clamping assembly. Many such machines are by necessity of function compact in nature. The need to operate at evermore increasing production speeds for cost competitiveness has resulted in machine designs with increasingly higher knife counts, and accordingly, limited amounts of space available for the knives and knife clamping assembly on the base member. Accordingly, knife clamping assemblies, as well as the knives they clamp, must be evermore compact to achieve these goals.
Traditionally, knife clamping assemblies used in woodworking machines have been relatively simple devices occupying significant space on the base members in which they mount. The knives used in these assemblies were commonly large planar elements of simple form that were shaped to allow for the repeated sharpening of the cutting edge. These knives, which due to their size were typically capable of sustaining a significant portion of the cutting loads, were generally secured in the clamping assembly in a 'sandwich' style arrangement using an actuator of some form. The actuator would cause the clamping components of the assembly to be drawn together or otherwise displaced so as to secure the knives therebetween.
Typical with such 'sandwich' style clamping assemblies is that the line of action of the force developed by the actuator intersects with the knife element, often towards its middle section. This often necessitates that the knife be formed to allow for the actuator, commonly a threaded fastener, to pass there through. The advantage of such an arrangement is that the majority, or in many cases all of the clamping force generated by the actuator serves to secure the knife between the clamping components. However as a result of the rather large size of the knife elements themselves, the clamping assemblies are typically bulky devices consuming significant space on the base member.
The advent of so called 'disposable' knives, often of a 'reversible' (or multiple edged) type, has placed increased demands on the clamping assembly. These knives, typically manufactured from higher quality materials, must be small and lightweight for cost effectiveness. Their compact nature precludes them from being primary load bearing elements and renders them significantly more difficult to secure within the clamping assembly.
Blades of the reversible type also pose additional constraints on the clamping assembly in that the clamping components cannot contact the knife is areas adjacent the unexposed cutting edge(s) since these edges can often be damaged from prior use. Already limited due to their smaller size, this further diminishes the support and contact areas that can be employed to maintain the knives in a stable position during operation. Securing such compact knife elements requires that the knives be rigidly clamped with proportionally higher clamping forces than traditional assemblies using larger, regrindable, knife elements.
The most common means to secure knives of a size or a shape that cannot be fastened in a 'sandwich' style configuration is to employ a clamping assembly that functions according to the principle of a third order lever. With this arrangement, the force developed by the actuator is applied to a clamping component which pivots about a fulcrum formed in the assembly. The line of action of the force developed by the actuator is positioned between the fulcrum and the knife. The clamping pressure achieved on the knife is a function of the distances between the fulcrum position, actuator location, and knife contact point according to the principles of a third order lever.
Clamping assemblies that function according to this principle have many advantages. Foremost such an arrangement permits for the line of action of the force generated by the actuator to lie adjacent the knife such that the knife need not be formed to allow the actuator to pass through the knife body itself. This is typically a requirement for securing compact knives, either of disposable, reversible, or regrindable type where the form and size of the knife precludes other clamping means. When properly sized and constructed, clamping assemblies based on this principle can also generate high clamping forces for securing the knives under the action of the cutting forces. Limited only by the space available within the base member, the clamping assembly can typically be sized and shaped to provide for adequate rigidity and sufficient space to accommodate actuators that can develop satisfactory clamping forces so as to be able to secure the knives during operation. Further, simple and reliable third order clamping assemblies can be constructed using only two clamping components and a simple mechanical actuator for securing the knife therebetween.
With such clamping assemblies, the most common configuration is for the actuator to act upon the clamping component positioned towards the outer periphery of the base member. This 'outer' clamping component is generally more accessible and can be more readily opened and closed by workers to effectuate the replacement of the knives. With this arrangement, the remainder of the assembly is affixed to the base member, usually in some form of cavity or 'pocket' sized and shaped for this purpose. The actuator draws the outer clamping component against the knife to secure it within the clamping assembly, which remains stationary with respect to the base member. As this outer clamping component often coincides with the topside of the assembly, this arrangement is commonly referred to as 'topside' clamping.
With the majority of clamping assemblies, the actuator is typically in the form of a threaded fastener such as a screw, a bolt, or a stud and nut combination. Mechanical fasteners of such type are simple, inexpensive, reliable, and can provide significant clamping force in a compact form. In order that the driving features of the fastener be readily accessible, it is most common that these be located on the same face or side of the base member as the outer clamping component. This avoids the need for workers to move to other areas in the machine to access the fasteners when changing knives.
The most common arrangement when using mechanical fasteners for the actuator is to have the fastener pass through the outer clamping member and into other assembly components below, or directly into the base member. When tightened, the fastener is gradually drawn against the outer clamping component to develop the contact force necessary to secure the knives in place. To effectuate a knife change, workers tighten or loosen the fastener as required to either release or secure the knives in the assembly.
As a result of their simplicity and ease of use, third order knife assemblies utilizing a topside clamping configuration and mechanical fasteners are in widespread use in the type of woodworking machines herein described. They are cost effective, versatile, and have proven reliable in service.
However they are not without problems. According to the principles of a third order lever, the clamping pressure achieved on the knife is a function of the force developed by the actuator and the distances between the fulcrum position, actuator location, and contact point between the outer clamping component and the knife. For a given configuration, the clamping pressure developed on the knife is directly proportional to the clamping force developed by the actuator. Should the force developed by the actuator be half of that intended by the designer, the clamping pressure developed on the knife shall similarly be at half the desired value.
Such is often the situation when mechanical fasteners are employed as the actuator. While simple and mechanically reliable, the force developed by the fastener is often difficult to predict and control with accuracy. Such factors as the variation in the fastener's tightening force (torque) and unpredictable nature of friction between contact surfaces result in a wide range of force developed by the fastener.
Further, because of the need for knife assemblies to be of a compact form to integrate properly with the foundation bodies, it is not always possible to achieve a third order configuration that is favourable for the development of high clamping pressures. To do this requires that the fulcrum be positioned far away from the actuator and the knife. With many base members, space constraints limit the placement of the fulcrum. This means that the size of the clamping force, and thereby the ability to carry external cutting loads, is dictated by the capabilities of the actuator, which is often variable and difficult to control as noted above.
In general, the requirement for compactness and high knife clamping pressures conspire to limit the strength that can be obtained with a third order assembly. While the fastener must be of sufficient size to provide the necessary force for securing the knife under the action of the cutting forces, it cannot be of a size or a form that would consume excessive amounts of space within the assembly. This could result in clamping components that are inadequately sized and shaped for acceptable strength to be achieved. While an oversized fastener may ensure that an adequate preload force is developed under all circumstances, it can result in unacceptable stresses within the individual components that comprise the clamping assembly.
To maximize component strength, most third order clamping assemblies securing knives of a compact nature employ smaller high strength fasteners. These fasteners consume less space in the assembly and allow for proportionally stronger clamping components. However achieving adequate function is dependent on the fasteners being tightened to comparatively high values relative to the fastener size. Further, these smaller fasteners lack rigidity which results in a clamping assembly of lower stiffness such that the displacement of the knife edge under the action of the cutting forces can be problematic.
Given that the reliability of most topside clamped third order assemblies is dependent on adequate preload being developed in the fastener, and in particular those using smaller high strength fasteners, it is typically necessary to ensure that factors that influence the clamping force developed by the bolt are controlled in the field. This often mandates that the fasteners be tightened to precise values using specialized equipment, and that the lubrication, cleanliness, and general condition of the fasteners be scrutinized. In the absence of such measures, inadequate bolt preload can compromise the function of the clamping assembly. This can lead to the knives being improperly secured in service.
Alternatives to topside clamped third order clamping assemblies exist. Such designs are often directed at eliminating the aforementioned dependence on adequate preload being developed by the actuator, or to circumvent space limitations on the base member such that high strength arrangements can be achieved.
For example, it is sometimes advantageous to construct assemblies that have the inner clamping component as the member being actuated. With this arrangement, the assembly is affixed and held stationary within a cavity or pocket formed for this purpose on the 'underside' of the base member. The actuator draws the inner clamping component against the knife to secure it in place within the clamping assembly. As with topside clamping arrangements, such underside clamping assemblies also frequently work according to the principles of a third order lever.
One of the main advantages of underside clamping arrangements is that they can often make a more effective use of space within the machine. The clamping assemblies can often be made comparatively larger than their topside mounted counterparts while still maintaining good integration with the base member. This permits for stronger and more rigid components to be constructed, and in the case of third order assemblies, a more favourable configuration for the development of high clamping pressures. Since the cutting forces for most of the woodworking machines herein described are generally directed against the knife from the underside, such underside arrangements are also favourable for reasons of strength and stiffness.
Of late, 'pivot' clamping arrangements that function according to the principles of a first order lever have materialized. With such configurations, the force developed by the actuator is applied to a clamping component which pivots about a fulcrum formed in the assembly. As per the principles of a first order lever, the line of action of the force developed by the actuator is located askew of both the fulcrum and the knife thereby allowing knives of a compact nature to be secured. However, unlike third order levers, the fulcrum's location is between the actuator and the contact point on the knife. When in use, the actuator pivots the clamping component about the fulcrum to secure the knife in place.
Such pivot clamping arrangements allow for favourable first order configurations to be achieved such that a high percentage of the actuator's force can be applied to the knife. This permits the actuator, typically a threaded fastener, to be made smaller or fewer in number while achieving the high preload force desired. This further allows the individual clamping components that comprise the assembly to be made rigid yielding an assembly of high overall stiffness. Since the line of action of the force developed by the actuator is also askew of the knife, such arrangements are generally well suited for securing knives of a compact nature. An example of such a first order pivot clamping assembly can be found in U.S. Pat. No. 5,996,655 to CAE Machinery Ltd.
While the aforementioned alternatives offer advantages in the form of stronger more rigid clamping assemblies that are less susceptible to inadequate preload being developed by the actuator, they suffer from some notable disadvantages as well. In general, such assemblies do not exhibit the same high ease of use as simple third order clamping assemblies constructed from two clamping components. As a result of reduced accessibility or added complexity, it can be more difficult for workers to make a knife change, in particular to clean the assembly of any wood debris. Such material, if left in place, could compromise the function and reliability of the assembly.
Pivot style arrangements and underside clamping configurations are also generally of a form that preclude their use in many types of woodworking machines. Generally as a result of their size and shape, they do not integrate well with all forms of base members and cannot be easily retrofitted to existing machines. This precludes their use in many applications for which their advantages would in general be beneficial.
Further, the drive for cost competitiveness has also pushed manufacturers to adopt more standardized knife assembly designs that can be applied to a broad spectrum of woodworking machines. Standardized knife clamping assembly designs are advantageous for the producer and consumer alike. The producer benefits from greater economies of scale that allow for production efficiencies. The consumer benefits from reduced component costs and fewer knife assembly components being required in inventory to support more than one type of woodworking machine in the production facility.


The invention relates to compositions comprising an organoclay and polyphenylene ether resin and blends containing polyphenylene ether resin. In a preferred embodiment, the compositions exhibit physical properties that are enhanced over compositions containing clay of the prior art. The invention also relates to methods to enhance the ductility of thermoplastic compositions as compared to compositions containing clay of the prior art. The invention also relates to articles made from the compositions.

Not applicable.
Not applicable.
1. Field of the Invention
The invention relates to compositions comprising an organically modified layered silicate clay generally referred to as organoclay and polyphenylene ether resin and blends containing polyphenylene ether resin.
In a preferred embodiment, the compositions exhibit physical properties that are enhanced over compositions containing clay of the prior art. The invention also relates to methods to enhance the ductility of thermoplastic compositions as compared to compositions containing clay of the prior art. The invention also relates to articles made from the compositions.
2. Brief Description of the Related Art
Many commercial articles, such as connectors and automotive under hood components, require levels of stiffness and heat resistance that are greater than most thermoplastic resins. Inorganic fillers have been used to increase the stiffness and heat resistance of thermoplastic resins, however, concomitant with an unacceptable loss in ductility for many applications.
Organoclay materials have been used in crystalline resins, e.g., polyesters and polyamide resins, to enhance the flame and/or temperature resistance characteristics. The utility of organoclay material to enhance the ductility of thermoplastic resins is believed to be novel and non-obvious.
The present invention relates to compositions comprising:
(i) polyphenylene ether resin and blends containing polyphenylene ether resin, and
(ii) an organoclay.
The invention also relates to methods to enhance the ductility of thermoplastic compositions as compared to compositions containing clay of the prior art. The invention also relates to articles made from the compositions and methods.
The description which follows provides further details regarding this invention.
Not applicable.
As used herein, organoclay is a layered silicate clay, derived from layered minerals, in which organic structures have been chemically incorporated. Illustrative examples of organic structures are trimethyldodecylammonium ion and N,Nxe2x80x2-didodecylimidazolium ion. Since the surfaces of clay layers, which have a lattice-like arrangement, are electrically charged, they are capable of binding organic ions. There is no limitation with respect to the layered minerals employed in this invention other than that they are capable of undergoing an ion exchange with the organic ions. The preferred organoclays are layered minerals that have undergone cation exchange with organo cations and/or onium compounds. Illustrative of such layered minerals are the kaolinite group and the montmorillonite group. It is also within the scope of this invention to employ minerals of the illite group which can include hydromicas, phengite, brammallite, glaucomite, celadonite and the like. Often, however, the preferred layered minerals include those often referred to as 2:1 layered silicate minerals like muscovite, vermiculite, saponite, hectorite and montmorillonite, wherein montmorillonite is often preferred. The layered minerals described above may be synthetically produced. However, most often they are naturally occurring and commercially available. A detailed description of the layered minerals can be found in U.S. Pat. No. 5,530,052 which is incorporated herein by reference.
The amount of organoclay present in the compositions of the invention can vary depending on the final properties desired. Generally, the level is adjusted to allow for the desired level of increased stiffness, heat resistance, and/or dimensional stability balanced against the level of achievable ductility. Typical levels include from about 1% to about 25% by weight, preferably between about 1% to about 15% by weight, based upon the entire weight of the composition.
Descriptions of useful resins for the practice of the present invention are provided as follows.
Polyphenylene Ether Resin and Blends Containing Polyphenylene Ether Resin.
Polyphenylene ether resin, hereinafter xe2x80x9cPPExe2x80x9d, per se, are known polymers comprising a plurality of structural units of the formula (I):
wherein for each structural unit, each Q1 is independently halogen, primary or secondary lower alkyl (e.g., alkyl containing up to 7 carbon atoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy, or halohydrocarbonoxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Q2 is independently hydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl, hydrocarbonoxy or halohydrocarbonoxy as defined for Q1. Preferably, each Q1 is alkyl or phenyl, especially C1-4 alkyl, and each Q2 is hydrogen.
Both homopolymer and copolymer PPE are included. The preferred homopolymers are those containing 2,6-dimethyl-1,4-phenylene ether units. Suitable copolymers include random copolymers containing, for example, such units in combination with 2,3,6-trimethyl-1,4-phenylene ether units. Also included are PPE containing moieties prepared by grafting vinyl monomers or polymers such as polystyrenes, as well as coupled PPE in which coupling agents such as low molecular weight polycarbonates, quinones, heterocycles and formals undergo reaction in known manner with the hydroxy groups of two PPE chains to produce a higher molecular weight polymer.
It will be apparent to those skilled in the art from the foregoing that the PPE contemplated for use in the present invention include all those presently known, irrespective of variations in structural units or ancillary chemical features.
The PPE generally have an intrinsic viscosity often between about 0.05-0.60 dl./g., preferably in the range of about 0.10-0.48 dl./g., all as measured in chloroform at 25xc2x0 C. It is also possible to utilize a high intrinsic viscosity PPE and a low intrinsic viscosity PPE in combination. By high viscosity is meant a PPE having an I.V. of at least about 0.30 dl/g, and conversely, by low is meant a PPE with an I.V. of less than about 0.30 dl/g, preferably less than about 0.20 dl/g. Determining an exact ratio, when two intrinsic viscosities are used, will depend somewhat on the exact intrinsic viscosities of the PPE used and the ultimate physical properties that are desired.
The PPE resin compositions of the present invention preferably contain at least one nonelastomeric polymer of an alkenylaromatic compound. Suitable polymers of this type may be prepared by methods known in the art including bulk, suspension and emulsion polymerization. They generally contain at least about 25% by weight of structural units derived from an alkenylaromatic monomer of the formula (II)
wherein G is hydrogen, lower alkyl or halogen; Z is vinyl, halogen or lower alkyl; and p is from 0 to 5. These resins include homopolymers of styrene, chlorostyrene and vinyltoluene, random copolymers of styrene with one or more monomers illustrated by acrylonitrile, butadiene, xcex1-methylstyrene, ethylvinylbenzene, divinylbenzene and maleic anhydride, and rubber-modified polystyrenes comprising blends and grafts, wherein the rubber is a polybutadiene or a rubbery copolymer of about 98-68% styrene and about 2-32% diene monomer. These rubber modified polystyrenes include high impact polystyrene (commonly referred to as HIPS). Non-elastomeric block copolymer compositions of styrene and butadiene can also be used that have linear block, radial block or tapered block copolymer architectures. They are commercially available from such companies as Fina Oil as under the trademark FINACLEAR and Phillips under the trademark K-RESINS.
The amount of the polymer of a nonelastomeric alkenylaromatic compound, when one is used, is an amount effective to improve the flow and processability of the composition. Improved flow can be indicated by reduced viscosity or reduced injection pressures needed to fill a part during an injection molding process. Generally, the nonelastomeric alkenylaromatic compound is utilized in the range of about 20% to about 60% by weight based on the total weight of the composition. The preferred range is about 30% to about 60% by weight; based on the total weight of the composition.
The compositions of the present invention may also contain at least one impact modifier. The impact modifier may be used alone or in combination with a nonelastomeric alkenylaromatic compound. The impact modifiers include block (typically diblock, triblock or radial teleblock) copolymers of alkenyl aromatic compounds and dienes. Most often at least one block is derived from styrene and at least one block from at least one of butadiene and isoprene. Especially preferred are the triblock and diblock copolymers comprising polystyrene blocks and diene derived blocks wherein the aliphatic unsaturation has been preferentially removed with hydrogenation. Mixtures of various copolymers are also sometimes useful. The weight average molecular weights of the impact modifiers are typically in the range of about 50,000 to 300,000. Block copolymers of this type are available commercially from a number of sources, including Phillips Petroleum under the trademark SOLPRENE, Shell Chemical Co. under the trademark KRATON, and Kuraray under the trademark SEPTON.
Various mixtures of the aforementioned impact modifiers are also sometimes useful. The amount of the impact modifier generally present, when one is used, is an amount effective to improve the physical properties, for example, the ductility of the composition when compared to the same composition without an impact modifier. Improved ductility can be indicated by increased impact strength, increased tensile elongation to break, or both increased impact strength and increased tensile elongation to break. Generally, the impact modifier is utilized in the range of about 1% to about 20% by weight based on the total weight of the composition. A preferred range is about 1% to about 8% by weight; based on the total weight of the composition. The exact amount and types or combinations of impact modifiers utilized will depend in part on the requirements needed in the final blend composition.
For compositions comprising polyphenylene ether resin, preferred compositions have the major components which make up the composition in an amount within the following preferred ranges:
Polyphenylene ether resin, (a) about 30 to about 70 parts;
Non-elastomeric polymer of an alkenylaromatic compound, (b) about 20 to about 60 parts; and
Organoclay, (c) about 1 to about 10 parts;
based on 100 parts by weight of (a), (b), and (c) together.
Compatibilized blends of polyphenylene ether resin and polyamide resin are another useful resin composition for the present invention. Compatibilized blends of a polyphenylene ether resin and a polyamide resin are generally known in the art. These blends are typically made through reactive compounding techniques involving addition of a compatibilizing agent to compositions containing polyphenylene ether resin and polyamide resin. The compatibilizing agent is thought to result in reaction products between the polyphenylene ether resin and a polyamide resin and that these reaction products improve the compatibility between the polyphenylene ether resin and polyamide resin. The improved compatibility results in enhanced physical properties such as, for example, increased ductility. Illustrative compatibilizing agents for blends of polyphenylene ether resin and polyamide resin include citric acid, maleic anhydride, fumaric acid, malic acid as well as various derivatives of the foregoing.
The ratio of polyphenylene ether resin to polyamide resin can vary widely but is preferably adjusted so that the polyamide resin remains the continuous phase. Preferably the polyamide is at least about 40% by weight of the total resin composition. Increasing the level of the polyamide results in enhanced ductility and flow and is often preferred. The resin compositions may contain more than one type of polyamide resin such as a blend of nylon 6 and nylon 6,6. Moreover, the amine to acid endgroup ratio of the polyamide resin may also be varied as well as the relative viscosity of the polyamide contained within the resin composition.
The polyphenylene ether resins useful in the present invention include all known polyphenylene ether resins. Preferable resins include poly(2,6-dimethylphenylene ether) as well as the copolymer resins of 2,6-dimethylphenol and 2,3,6-trimethylphenol. These and other variations of the polyamide and the polyphenylene ether resins do not detract from the present invention.
The compatibilized blend of polyphenylene ether resin and polyamide resin may additionally contain various property modifiers such as elastomers for ductility enhancement. Useful elastomers for this purpose are known in the art and include, for example, styrenic block copolymers and various acid functionalized ethylene-propylene copolymers (e.g., EP-graft-maleic anhydride). Especially preferred are the so called elastomeric block copolymers, for example, A-B-A triblock copolymers and A-B diblock copolymers. The A-B and A-B-A type block copolymer rubber additives which may be used are thermoplastic rubbers comprised of one or two alkenyl aromatic blocks which are typically styrene blocks and a rubber block, e.g., a butadiene block which may be partially or totally hydrogenated. Mixtures of these triblock copolymers and diblock copolymers are especially preferred in the present compositions.
Suitable A-B and A-B-A type block copolymers are disclosed in, for example, U.S. Pat. Nos. 3,078,254, 3,402,159, 3,297,793, 3,265,765, and 3,594,452 and U.K. Patent 1,264,741. Examples of typical species of A-B and A-B-A block copolymers include polystyrene-polybutadiene (SBR), polystyrene-poly(ethylene-propylene), polystyrene-polyisoprene, poly(xcex1-methylstyrene)-polybutadiene, polystyrene-polybutadiene-polystyrene (SBR), polystyrene-poly(ethylene-butylene)-polystyrene, polystyrene-polyisoprene-polystyrene and poly(xcex1-methylstyrene)-polybutadiene-poly(xcex1-methylstyrene), as well as the selectively hydrogenated versions thereof. Mixtures of the aforementioned block copolymers are also useful. Such A-B and A-B-A block copolymers are available commercially from a number of sources, including Phillips Petroleum under the trademark SOLPRENE, Shell Chemical Co., under the trademark KRATON, Dexco under the tradename VECTOR, and Kuraray under the trademark SEPTON. Other property modifiers include nucleating agents, stabilizers, pigments, dyes, and mineral fillers and reinforcing agents.
Also useful elastomers include functionalized elastomeric polyolefins such as elastomeric polyolefins containing at least one moiety of the group consisting of anhydride, epoxy, oxazoline, and orthoester. The essential structural units of the elastomeric polyolefin are derived from ethylene and at least one C3-8 1-olefin, such as, propylene, 1-butene, 1-hexene, and 1-octene. The proportions of ethylene and at least one C3-8 1-olefin are not critical provided that they together constitute the major portion of the polymer.
In a preferred embodiment, the functionalized elastomeric polyolefin is a functionalized ethylene-propylene rubber or a functionalized ethylene-propylene-diene elastomer. The diene portion is at least one non-conjugated diene, such as ethylidene norbornene, 1,4-hexadiene, or dicyclopentadiene. These elastomeric polyolefins are known in the art as EPR and EPDM elastomers.
A useful amount of the optional elastomeric block copolymers is between about 1% and about 15% by weight, preferably between about 1% and about 10% by weight, wherein the weight percentages are based on the entire weight of the composition. Mixtures of the previous described impact modifiers are also useful.
Flame Retardant
The resins of the present invention may also comprise at least one flame retardant, generally a halogenated material, an organic phosphate, or a combination of the two. For resin compositions containing polyphenylene ether or polycarbonate resin, the organic phosphate class of materials are generally preferred. The organic phosphate is preferably an aromatic phosphate compound of the formula (III):
where R is the same or different and is alkyl, cycloalkyl, aryl, alkyl substituted aryl, halogen substituted aryl, aryl substituted alkyl, halogen, or a combination of any of the foregoing, provided at least one R is aryl.
Examples include phenyl bisdodecyl phosphate, phenylbisneopentyl phosphate, phenyl-bis (3,5,5xe2x80x2-tri-methyl-hexyl phosphate), ethyldiphenyl phosphate, 2-ethyl-hexyldi(p-tolyl) phosphate, bis-(2-ethylhexyl) p-tolylphosphate, tritolyl phosphate, bis-(2-ethylhexyl) phenyl phosphate, tri-(nonylphenyl) phosphate, di (dodecyl) p-tolyl phosphate, tricresyl phosphate, triphenyl phosphate, dibutylphenyl phosphate, 2-chloroethyldiphenyl phosphate, p-tolyl bis (2,5,5xe2x80x2-trimethylhexyl) phosphate, 2-ethylhexyldiphenyl phosphate, and the like. The preferred phosphates are those in which each R is aryl. Especially preferred is triphenyl phosphate, which may be either unsubstituted or substituted, for example, isopropylated triphenyl phosphate.
Alternatively, the organic phosphate can be a di- or polyfunctional compound or polymer having the formula (IV), (V), or (VI) below:
including mixtures thereof, in which R1, R3 and R5 are, independently, hydrocarbon; R2, R4, R6 and R7 are, independently, hydrocarbon or hydrocarbonoxy; X1, X2 and X3 are halogen; m and r are 0 or integers from 1 to 4, and n and p are from 1 to 30.
Examples include the bis diphenyl phosphates of resorcinol, hydroquinone and bisphenol-A, respectively, or their polymeric counterparts.
Methods for the preparation of the aforementioned di- and polyfunctional aromatic phosphates are described in British Patent No. 2,043,083.
Another group of useful flame retardants include certain cyclic phosphates, for example, diphenyl pentaerythritol diphosphate, as a flame retardant agent for polyphenylene ether resins, as is described by Axelrod in U.S. Pat. No. 4,254,775.
Also suitable as flame-retardant additives for this invention are the phosphoramides of the formula (VII):
wherein each A moiety is a 2,6-dimethylphenyl moiety or a 2,4,6-trimethylphenyl moiety. These phosphoramides are piperazine-type phosphoramides. These additives are known in the art and have been described in Talley, J. Chem. Eng. Data, 33, 221-222 (1988). When polyamide resins are used as part of the composition, these piperazine-type phosphoramides are especially useful as they are believed to have less interactions with the polyamides then the organo-ester type phosphates.
Preferred phosphate flame retardants include those based upon resorcinol such as, for example, resorcinol tetraphenyl diphosphate, as well as those based upon bis-phenols such as, for example, bis-phenol A tetraphenyl diphosphate. Also preferred are the aforementioned piperazine-type phosphoramides. Phosphates containing substituted phenyl groups are also preferred. In an especially preferred embodiment, the organophosphate is selected from the group consisting of butylated triphenyl phosphate ester, resorcinol tetraphenyl diphosphate, bis-phenol A tetraphenyl diphosphate, and mixtures containing at least one of the foregoing.
The flame retardant is present in at least the minimum amount necessary to impart a degree of flame retardancy to the composition to pass the desired UL-94 protocol. The particular amount will vary, depending on the molecular weight of the organic phosphate, the amount of the flammable resin present and possibly other normally flammable ingredients which might also be included in the composition.
Halogenated materials are also a useful class of flame retardants. These materials are preferably aromatic halogen compounds and resins of the formula (VIII):
wherein R is an alkylene, alkylidene or cycloaliphatic linkage, e.g., methylene, ethylene, propylene, isopropylene, isopropylidene, butylene, isobutylene, amylene, cyclohexylene, cyclopentylidene, etc.; a linkage selected from the group consisting of either oxygen ether; carbonyl; amine; a sulfur containing linkage, e.g., sulfide, sulfoxide, sulfone; a phosphorus containing linkage; etc. R can also consist of two or more alkylene or alkylidene linkages connected by such groups as aromatic, amino, ether, carbonyl, sulfide, sulfoxide, sulfone, a phosphorus containing linkage, etc. Other groups which are represented by R will occur to those skilled in the art, including those found in U.S. Pat. Nos. 4,692,490 and 4,191,685.
Ar and Arxe2x80x2 are mono- or polycarbocyclic aromatic groups such as phenylene, biphenylene, terphenylene, naphthylene, etc. Ar and Arxe2x80x2 may be the same or different.
Y is a substituent selected from the group consisting of organic, inorganic or organometallic radicals. The substituents represented by Y include (1) halogen, e.g., chlorine, bromine, iodine, fluorine or (2) ether groups of the general formula OE, wherein E is a monovalent hydrocarbon radical similar to X or (3) monovalent hydrocarbon groups of the type represented by R or (4) other substituents, e.g., nitro, cyano, etc., said substituents being essentially inert provided there be at least one and preferably two halogen atoms per aryl nucleus.
X is a monovalent hydrocarbon group exemplified by the following: alkyl, such as methyl, ethyl, propyl, isopropyl, butyl, decyl, etc; aryl groups, such as phenyl, naphthyl, biphenyl, xylyl, tolyl, etc; aralkyl groups such as benzyl, ethylphenyl, etc.; cycloaliphatic groups, such as cyclopentyl, cyclohexyl, etc.; as well as monovalent hydrocarbon groups containing inert substituents therein. It will be understood that where more than one X is used they may be alike or different.
The letter d represents a whole number ranging from 1 to a maximum equivalent to the number of replaceable hydrogens substituted on the aromatic rings comprising Ar or Arxe2x80x2. The letter e represents a whole number ranging from 0 to a maximum controlled by the number of replaceable hydrogens on R. The letters a, b, and c represent whole numbers including 0. When b is not 0, neither a nor c may be 0. Otherwise either a or c, but not both, may be 0. Where b is 0, the aromatic groups are joined by a direct carbon-carbon bond.
The hydroxyl and Y substituents on the aromatic groups, Ar and Arxe2x80x2 can be varied in the ortho, meta or para positions on the aromatic rings and the groups can be in any possible geometric relationship with respect to one another.
Included within the scope of the above formula are biphenols of which the following are representative: 2,2-bis-(3,5-dichlorophenyl)-propane; bis-(2-chlorophenyl)-methane; bis(2,6-dibromophenyl)-methane; 1,1-bis-(4-iodophenyl)-ethane; 1,2-bis-(2,6-dichlorophenyl)-ethane; 1,1-bis-(2-chloro-4-iodophenyl)ethane; 1,1-bis-(2-chloro-4-methylphenyl)-ethane; 1,1-bis-(3,5-dichlorophenyl)-ethane; 2,2-bis-(3-phenyl-4-bromophenyl)-ethane; 2,6-bis-(4,6-dichloronaphthyl)-propane; 2,2-bis-(2,6-dichlorophenyl)-pentane; 2,2-bis-(3,5-dichromophenyl)-hexane; bis-(4-chlorophenyl)-phenyl-methane; bis-(3,5-dichlorophenyl)-cyclohexylmethane; bis-(3-nitro-4-bromophenyl)-methane; bis-(4-hydroxy-2,6-dichloro-3-methoxyphenyl)-methane; 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane 2,2 bis-(3-bromo-4-hydroxyphenyl)-propane.
The preparation of these and other applicable bisphenols is known in the art. They are most commonly prepared by condensation of two moles of a phenol with a single mole of a ketone or aldehyde. In place of the divalent aliphatic group in the above examples may be substituted oxygen, sulfur, sulfoxy, etc.
Included within the above structural formula are: 1,3-dichlorobenzene, 1,4-dibrombenzene, 1,3-dichloro-4-hydroxybenzene and biphenyls such as 2,2xe2x80x2-dichlorobiphenyl, polybrominated 1,4-diphenoxybenzene, 2,4xe2x80x2-dibromobiphenyl, and 2,4xe2x80x2-dichlorobiphenyl as well as decabromo diphenyl oxide, and the like.
Also useful are oligomeric and polymeric halogenated aromatic compounds, such as, for example, a copolycarbonate of bisphenol A and tetrabromobisphenol A and a carbonate precursor, e.g., phosgene. Metal synergists, e.g., antimony oxide, may also be used with the flame retardant.
The composition can be further modified, if desired, by including one or more additives often used with thermoplastic polymers, some of which may serve to beneficially affect the chemical and physical properties. Examples are mineral fillers, including clay, reinforcing agents, for example, glass fibers, flakes or spheres, plasticizers, flame retardants, stabilizers, antioxidants, colorants, processing aids, and so forth.
The resin compositions used in the present invention can be prepared by a variety of methods involving intimate admixing of the materials with any additional additives desired in the formulation. Suitable procedures include solution blending and melt blending. Because of the availability of melt blending equipment in commercial polymer processing facilities, melt processing procedures are generally preferred. Examples of equipment used in such melt compounding methods include: co-rotating and counter-rotating extruders, single screw extruders, disc-pack processors and various other types of extrusion equipment. In some instances, the compounded material exits the extruder through small exit holes in a die and the resulting strands of molten resin are cooled by passing the strands through a water bath. The cooled strands can be chopped into small pellets for packaging and further handling.
All of the ingredients may be added initially to the processing system, or else certain additives may be pre-compounded with each other. For example, it is often preferred to predisperse the organo-clay into a resin at a higher loading than in the desired final product to make a concentrate. The concentrate is then added in an amount necessary to achieve the desired final amount. Concentrates are especially useful and desirable when a crystalline resin, e.g. polyamide, polyester, or polyolefin, is used as at least part of the resin composition. In one embodiment, it is also desirable to disperse the organoclay in a low I.V. PPE, preferably having an I.V. of less than about 0.20 dl/g as measured in chloroform at 23xc2x0 C. It is also sometimes advantageous to employ at least one vent port in each section between the feed ports to allow venting (either atmospheric or vacuum) of the melt. Those of ordinary skill in the art will be able to adjust blending times and temperatures, as well as component addition location and sequence, without undue additional experimentation.
It should be clear that articles formed out of the thermoplastic compositions described herein are another embodiment of the present invention.
All patents cited are incorporated herein by reference.