A GI tract stimulator and/or monitor IMD comprising a housing enclosing electrical stimulation and/or monitoring circuitry and a power source and an elongated flexible member extending from the housing to an active fixation mechanism adapted to be fixed into the GI tract wall is disclosed. After fixation is effected, the elongated flexible member bends into a preformed shape that presses the housing against the mucosa so that forces that would tend to dislodge the fixation mechanism are minimized. The IMD is fitted into an esophageal catheter lumen with the fixation mechanism aimed toward the catheter distal end opening whereby the bend in the flexible member is straightened. The catheter body is inserted through the esophagus into the GI tract cavity to direct the catheter distal end to the site of implantation and fix the fixation mechanism to the GI tract wall. The IMD is ejected from the lumen, and the flexible member assumes its bent configuration and lodges the hermetically sealed housing against the mucosa. A first stimulation/sense electrode is preferably an exposed conductive portion of the housing that is aligned with the bend of the flexible member so that it is pressed against the mucosa. A second stimulation/sense electrode is located at the fixation site.

The present invention pertains to implantable medical devices (IMDs), particularly gastrointestinal stimulator and/or monitor IMDs adapted to be implanted within the interior of the gastrointestinal tract having one or more than one stimulation/sense electrode attached to or pressing against an interior surface site of the gastrointestinal tract wall to conduct electrical stimulation to the site and to conduct electrical signals of the GI tract from the site or other physiologic signals from the interior of the gastrointestinal tract.
The GI tract comprises the esophagus, the stomach, the small intestine, the large intestine, the colon, and the anal sphincter and is generally described as having a tract axis. Like other organs of the body, most notably the heart, these organs naturally undergo regular rhythmic contractions. In particular these contractions take the form of peristaltic contractions and are essential for the movement of food through each of the respective organs. Like the heart, these contractions are the result of regular rhythmic electrical depolarizations of the underlying tissue.
In some individuals, however, either the regular rhythmic peristaltic contractions do not occur or the regular rhythmic electrical depolarizations do not occur or both do not occur. In each of these situations the movement of food may be seriously inhibited or even disabled. Such a condition is often called xe2x80x9cgastroparesisxe2x80x9d when it occurs in the stomach. Gastroparesis is a chronic gastric motility disorder in which there is delayed gastric emptying of solids or liquids or both. Symptoms of gastroparesis may range from early satiety and nausea in mild cases to chronic vomiting, dehydration, and nutritional compromise in severe cases. Similar motility disorders occur in the other organs of the GI tract, although by different names.
Diagnosis of gastroparesis is based on-demonstration of delayed gastric emptying of a radio-labeled solid meal in the absence of mechanical obstruction. Gastroparesis may occur for a number of reasons. Management of gastroparesis involves four areas: (1) prokinetic drugs, (2) antiemetic drugs, (3) nutritional support, and (4) surgical therapy (in a very small subset of patients.) Gastroparesis is often a chronic, relapsing condition; 80% of patients require maintenance antiemetic and prokinetic therapy and 20% require long-term nutritional supplementation. Other maladies such as tachygastria or bradygastria can also hinder coordinated muscular motor activity of the GI tract, possibly resulting in either stasis or nausea or vomiting or a combination thereof.
The undesired effect of these conditions is a reduced ability or complete failure to efficiently propel intestinal contents down the digestive tract. This results in malassimilation of liquid or food by the absorbing mucosa of the intestinal tract. If this condition is not corrected, malnutrition or even starvation may occur. Moreover nausea or vomiting or both may also occur. Whereas some of these disease states can be corrected by medication or by simple surgery, in most cases treatment with drugs is not adequately effective, and surgery often has intolerable physiologic effects on the body.
The concept of electrically stimulating the gastrointestinal tract to restore its proper function originated many years ago, and one early approach is disclosed in commonly assigned U.S. Pat. No. 3,411,507. The ""507 patent discloses a system for gastrointestinal stimulation which uses an electrode positioned on a nasogastric catheter and an electrode secured to the skin over the abdomen. In operation, the nasogastric catheter is inserted into the patient""s stomach while the patient is lying down such that the electrode is positioned in close proximity to the pylorus of the stomach. Electrical stimulation is delivered for the first five seconds of every minute until peristaltic activity is initiated. The ""507 patent also discloses using electrical stimulation of the same order of magnitude as the normal range of periodicity of the inherent peristaltic pacemaker action of the duodenum. The stimulation process is discontinued after the first bowel movement. The ""507 patent system is a short-term device that is only useful for patients in a hospital setting, and particularly non-ambulatory patients.
Sensing of the peristaltic electrical wave and gastrointestinal stimulation at various sites on or in the GI tract wall of the digestive system or nerves associated therewith have been conducted to diagnose and treat these various conditions over the years since the publication of the ""507 patent. Fully implantable gastrointestinal stimulation systems have been developed and clinically implanted in patient""s bodies allowing the patients to be ambulatory. The history and breadth of such sensing and GI tract stimulation is set forth in commonly assigned U.S. Pat. Nos. 5,507,289, 6,026,326, 6,104,965, 6,216,039, and in further U.S. Pat. Nos. 5,690,691 and 6,243,607, for example. The implantable gastrointestinal stimulation systems are referred to as xe2x80x9cpacemakersxe2x80x9d in certain of these patents and the literature because of their resemblance to implantable cardiac pacemakers in structure and function.
In such fully implantable gastrointestinal stimulation systems, electrical stimuli are applied from an implantable pulse generator (IPG) through elongated leads and lead borne electrodes affixed at sites in the body of the patient or the GI tract wall or the vagus nerve that permit the electrical stimulus to produce a local contraction of a desired portion of the GI tract. The IPG is typically implanted below the skin surface in the abdominal region and leads coupled to the IPG extend to sites of the gastrointestinal tract and/or the vagus nerve where stimulation/sense electrodes are affixed.
The sites of the GI tract wall typically comprise the outermost serosa or sub-serosally in the inner, circumferential and longitudinal (and oblique in the case of the stomach) smooth muscle layers referred to as the xe2x80x9cmuscularis externaxe2x80x9d (although the above referenced ""691 patent suggests locating the electrodes within the stomach cavity against the inner stomach surface mucosa). The above-referenced ""607 patent discloses one method and system for electrical stimulation of smooth muscle with intact local gastric nerves comprising a portion of the GI tract. The electrical stimulation of the smooth muscle effects local contractions at sites of a portion of the GI tract that are artificially propagated distally therethrough in order to facilitate or aid at least a partial emptying of such portion. This stimulation attempts to create a simulated system that reproduces the spatial and temporal organization of normal gastric electrical activity by creating and controlling local circumferential non-propagated contractions. In this simulated gastric pacing system, each local circumferential contraction is invoked by applying an electrical stimulus to the smooth muscle circumferentially about the portion of the GI tract in a plane substantially perpendicular to the longitudinal axis of the portion. The electrical stimulus is applied at a proximal location and at least one distal location. The distal location is in axially spaced relationship relative to the proximal location. Further, the applied electrical stimulus is selected to be sufficient to stimulate the smooth muscle to produce the local circumferential contractions at the proximal and distal locations.
The Medtronic(copyright) Itrel III(copyright) Model 7425 IPG and pairs of the unipolar Model 4300 or Model 4301 or Model 4351 xe2x80x9csingle passxe2x80x9d leads available from MEDTRONIC, INC. have been implanted to provide stimulation to sites in the stomach wall to treat chronic nausea and vomiting associated with gastroparesis. The unipolar electrode of these leads comprises a length of exposed lead conductor and is of the type disclosed in commonly assigned U.S. Pat. Nos. 5,425,751, 5,716,392 and 5,861,014. The above-referenced ""039 patent and the ""014 patent disclose the Model 4300 lead sewn through the serosa laterally into the muscularis externa to dispose the stimulation/sense electrode therein. A large incision is necessary to access the site, and a needle is used to perforate the serosa and muscularis externa laterally without fully penetrating the wall and to draw the stimulation/sense electrode into the muscularis externa. A laparascopic approach can be taken, but it is difficult to maneuver the needle to effect the fixation of the stimulation/sense electrode at the site. It is suggested in the ""039 patent that two or more electrodes of this type can be formed along the length of the lead body that would be sewn laterally through and disposed within the muscularis externa.
A further U.S. Pat. No. 5,292,394 discloses a percutaneous system that provides for temporary stimulation, sensing, delivery of fluids and nutrients, and pH sensing within the gastrointestinal tract. A plurality of distal stimulation/sense electrodes are located within the stomach cavity pressing against the mucosa, and distal pressure and pH sensors are located in the stomach cavity and the small intestine. The sensors and stimulation/sense electrodes are electrically coupled to an external pulse generator/controller by lead conductors extending through a percutaneously introduced access device or tube that the distal components were introduced through. Fluids can also be introduced directly into the stomach or withdrawn from the stomach. The percutaneous pathway is problematic in that the seal around the percutaneous access device that is necessary to prevent leakage of stomach acid into the peritoneal cavity or just subcutaneously around the device.
Ways of attaching pH sensors within the esophagus via the patient""s mouth employing an endoscope are disclosed in U.S. Pat. No. 6,258,896. The attachment embodiments disclosed in the ""896 patent include use of a loop drawn about a mass of mucosal tissue, a tether tied to a tooth in the patient""s mouth, and a recital of the use of hooks, barbs, sutures, tacks, staples, other structures that penetrate the mucosa. It is also suggested that the fixation mechanism be made biodegradable so that the biosensor capsule would be released after a monitoring time period and pass through the GI tract.
Ways of attaching pH sensors within the stomach via the mouth employing an endoscope are disclosed in an article by Swain et al. entitled xe2x80x9cAn endoscopically deliverable tissue-transfixing device for securing biosensors in the gastrointestinal tractxe2x80x9d, GASTOINTESTINAL ENDOSCOPY vol. 40, no. 6, pp. 730-734, 1994. The attachment mechanism involves use of suction to draw a fold of the stomach wall together and insertion of a preformed, Nylon, H-shaped tag through the fold of the stomach wall. While pH sensors are described, it is suggested that the same equipment and fixation mechanism can be employed to fix other medical devices within the stomach, including xe2x80x9celectrical pacemakersxe2x80x9d, presumably to stimulate the stomach wall. No specific sensing or stimulation electrodes are described.
In the field of cardiac stimulation, cardiac pacing leads having bipolar and unipolar pace/sense electrodes have long been used in conjunction with pacing system IPGs to conduct pacing pulses generated by the IPG to a site of the heart and cardiac signals from the site to the IPG. Pacing leads are typically provided with a passive fixation or an active fixation mechanism at the lead body distal end that is passively or actively engaged with cardiac tissue to anchor a distal tip electrode at a desired site in or on the heart. Passive fixation generally involves an atraumatic fixation lodging the distal electrode against the endocardium or within a coronary blood vessel. Positive or active fixation generally involves a more traumatic penetration of a fixation mechanism into the myocardium from an endocardial or epicardial surface, and the active fixation mechanism commonly comprises a distal pace/sense electrode. Typically, the active fixation mechanism comprises the single pace/sense electrode or one of the bipolar pace/sense electrodes, but can be separate and electrically isolated from the pace/sense electrodes.
Endocardial pacing leads having either active fixation or passive fixation mechanisms are implanted by a transvenous route into a heart chamber to locate the distal pace/sense electrode(s) at a selected site in the heart chamber where an active or passive fixation mechanism is deployed to maintain the pace/sense electrode affixed at the site. Endocardial active fixation pacing leads typically employ extendable and retractable helixes of hooks that are retracted during introduction and are extended distally from the lead body distal end at the site of attachment.
Epicardial pacing leads are implanted by exposure of the epicardium of the heart through a limited thoracotomy. The distal end of the epicardial lead formed with one or two pace/sense electrodes and an active fixation mechanism supported by an electrode head is affixed through the epicardium and within the myocardium. Active fixation mechanisms of epicardial pacing leads typically comprise a tissue penetrating, self-affixing mechanism extending away from a support or base or plate of the electrode head. The fixation mechanism is forced into the myocardium typically employing an insertion tool engaging the electrode head until it is fully seated within the myocardium and the plate bears against the epicardium. The plate is typically formed with a tissue ingrowth encouraging fabric or lattice, whereby tissue ingrowth about the plate assists in chronic anchoring to the heart.
The dislodgement of pace/sense electrodes and the fracture of the lead conductor or the insulation about it were serious concerns in the early years of implantable cardiac pacemakers. A combined pacemaker IPG, pace/sense electrodes, and active fixation barb mechanism are disclosed in U.S. Pat. No. 3,835,864 that is intended to overcome the problems associated with lead fracture and electrode dislodgement. A system and method are disclosed for introducing the unitary pacemaker through a transvenous route, lodging it deeply in the right ventricular apex, and deploying the active fixation barbs. Other implantation sites are suggested, including in relation to sphincters, but no particular examples of the implantation are described. The disclosed unitary pacemaker has not been clinically implanted in humans.
To our knowledge, none of the above-described medical devices have been employed in the field of gastrointestinal stimulation. There remains a need to provide an implantable GI tract stimulator for providing GI tract electrical stimulation at sites in the stomach that can be introduced into the stomach cavity and affixed to the stomach wall without an invasive surgical procedure, that is simple to affix at a desired site, that is securely affixed for temporary or chronic stimulation, and that can be removed when necessary.
The present invention is preferably embodied in a GI tract stimulator or monitor IMD that can be introduced through the esophagus, that is simple to affix to the stomach or GI tract wall at a desired site, that is securely affixed thereto, and that can be removed when necessary. The IMD is preferably a GI tract stimulator and/or a physiologic signal monitor.
The GI tract stimulator or monitor of the present invention comprises a hermetically sealed housing enclosing electrical stimulation and/or monitoring circuitry and a power source and an elongated flexible member extending from the housing to an active fixation mechanism adapted to be fixed into the mucosa or sub-mucosal tissue. After fixation is effected, the elongated flexible member bends into a preformed shape that presses the housing against the mucosa so that forces that would tend to dislodge the fixation mechanism are minimized.
Preferably, a GI tract stimulator or monitor IMD in accordance with the present invention comprises a hermetically sealed housing enclosing electrical stimulation and/or monitoring circuitry and a power source and supporting a first stimulation/sense electrode adapted to press against the mucosa of the stomach wall. An elongated flexible member is fixed at a member fixed end to the housing and extends away from the housing to a member free end supporting an active fixation mechanism and a second stimulation/sense electrode. The active fixation mechanism is adapted to grip a fold of the mucosa or perforate the mucosa and lodge in the muscularis externa of the GI tract wall when introduced against the mucosa. The active fixation mechanism and second stimulation/sense electrode can be separately supported at the member free end or combined together. A conductor is encased within or extends through a first lumen of the flexible member and is coupled to the second stimulation/sense electrode and to the IPG circuitry within the hermetically sealed housing.
The flexible member is formed to assume a bend intermediate the member fixed end and the member free end when the flexible member is unrestrained. However, the flexible member can be straightened to axially align and enable the introduction of the straightened flexible member and hermetically sealed housing through the lumen of an esophageal catheter. Preferably, an elongated beam of shape memory alloy having the bend formed in it is encased within or extends through a second lumen of the flexible member.
In use, the GI tract stimulator or monitor IMD is fitted into the lumen of an esophageal tube or catheter with the fixation mechanism aimed toward the catheter distal end opening whereby the bend in the flexible member is straightened and the fixation mechanism is contained within the catheter lumen. The catheter (and endoscope) is inserted through a curved mouth and throat guard inserted into the patient""s mouth, and the catheter distal end is advanced through the esophagus and lower esophageal sphincter and into the stomach cavity. An endoscope can also be inserted through the catheter lumen or alongside the esophageal catheter to enable visualization of the stomach wall to locate a fixation site and to observe the fixation. The catheter distal end is directed to the site of implantation
The fixation mechanism is then deployed to fix the flexible member free end to the stomach wall. The fixation mechanism can be any of those employed to fix IMDs in the body. Preferred forms of fixation mechanisms comprise a helix, one or more hook, or clips or pincers that penetrate through the mucosa into the muscularis externa or pinch a fold of the mucosa. The mucosa can be drawn against the esophageal catheter distal end by drawing suction through the catheter lumen. The fixation mechanism is then pushed or screwed into the stomach wall or the clip or pincers are released to engage the stomach wall fold.
Then, the esophageal catheter is withdrawn to release the GI tract stimulator, whereupon the flexible member assumes its bent configuration and lodges the hermetically sealed housing against the mucosa. The first stimulation/sense electrode is preferably an exposed conductive portion of the housing that is aligned with the bend of the flexible member so that it is pressed against the mucosa.
For temporary use, the fixation mechanism can be made of a material that is degraded by stomach acid over time to release the GI tract stimulator or monitor IMD and allow it to pass through the GI tract. Alternatively, the removal can be effected by straightening the bend and withdrawing the GI tract stimulator or monitor IMD through the lumen of an esophageal catheter introduced in the same way into the stomach. A wire can be advanced through the catheter lumen to snare or otherwise engage the GI tract stimulator and draw it into the catheter lumen.
The active fixation mechanisms preferably extend away from a stop or plate of the electrode head and are shaped to penetrate through the mucosa and into the muscularis externa upon application of penetrating force through the electrode head to the GI tract wall to draw the stop or plate against the mucosa and operatively contact the stimulation/sense electrode with the GI tract wall. The stop or plate inhibits further advancement of the active fixation mechanism and perforation of the GI tract wall, and the active fixation mechanism cooperates with the stop or plate to inhibit dislodgement of the stimulation/sense electrode from operative contact with the GI tract wall.
The active fixation mechanisms are selected from helixes and barbed hooks having sharpened tips or free ends that perforate the mucosa and lodge in the muscularis externa or the submucosa. The maximal depth of penetration from the stop or plate is preferably in the range of 1 mm to 15 mm when the site comprises the antrum or in the range of 1 mm to 10 mm when the site comprises corpus or fundus to ensure that the free end does not extend substantially through the stomach wall.
The helixes and hooks can be formed of bio-compatible conductive materials that are coupled with the lead conductors and un-insulated at least in part to operate as the sensing and/or stimulation electrodes. The stimulation/sense electrode surface can be coated with a porous platinized structure to reduce polarization and/or an anti-inflammatory agent that inhibits inflammation that can negatively affect the ability to sense electrical signals of the GI tract or to efficiently deliver electrical stimulation. The anti-inflammatory agents can be embedded into a monolithic controlled release device (MCRD) carried by the electrode head.
The expression xe2x80x9cstimulation/sense electrodexe2x80x9d as used herein applies to stimulation electrodes that are employed to stimulate tissue or sense electrodes to sense electrical signals in the tissue or electrodes that are used to perform both functions.
This summary of the invention has been presented here simply to point out some of the ways that the invention overcomes difficulties presented in the prior art and to distinguish the invention from the prior art and is not intended to operate in any manner as a limitation on the interpretation of claims that are presented initially in the patent application and that are ultimately granted.

Implantable medical device affixed internally within the gastrointestinal tract


The invention relates to a vegetation support (10) consisting of a mat of entangled organic fibers (14) which form said vegetation support (10). A substrate (20) is introduced into the hollow spaces of the mat (12) and a plant material (22) able to germinate, especially seeds, spores, sprouts or the like, is planted on an upper side (16) of the mat (12). The fibers (14) of the mat (12) are secured against detachment from the mat (12). The inventive vegetation support (10) is characterized in that the mat (12) fibers (14) are coconut fibers and that a plant-compatible binding agent (28) is used to prevent the fibers (14) from becoming detached from the mat (12). The binding agent is applied to the surfaces of at least a part of the fibers (14) and ensures that the fibers (14) of the mat (12) are at least partly glued to each other.

The present invention relates to a vegetation support comprising a mat made of interleaved organic fibres.
Such pre-grassed vegetation supports, as known from DE 36 31 716 C2, serve as grass lining for rooves, inclined surfaces, in particular slopes and other surfaces which are to be covered by a layer of vegetation. These vegetation supports known hitherto comprise a middle layer of interleaved fibres and an upper lower layer of an inorganic formed fabric, which are connected to one another by means of stepping or perforation and to the middle layer. The formed fabrics of the upper and the lower layer accordingly serve to reinforce the vegetation support, that is, they absorb the tensile forces from laying on inclined surfaces. The formed fabrics also serve to prevent loosening of the relatively loose only fibres located in the middle support layer.
Such vegetation supports have proven themselves widely and in particular it is an advantage with such vegetation supports that prior to laying, substrate is applied to the vegetation support and germination-capable plant material is applied to the vegetation support or introduced into the vegetation support, and the germination-capable plant material is already grown into the support layer. The losses in plant material after application of the already grassed vegetation support in this way to the surface to be built up are accordingly kept low.
The disadvantage of these vegetation supports known to date is that the stepping between the upper and lower formed fabric layers is relatively expensive and that the formed fabric layers additionally consist of a material which cannot rot and which can be recycled. With the natural landscaping of surfaces it is important, however, that the material of the vegetation support comprises a fully recyclable material, whereby special attention is paid to the fact that raw materials which as far as possible grow again are put to use for the material of the vegetation support.
Another disadvantage is that the middle support layer of this known vegetation support rots relatively quickly. It is true that rotting of the support layer is basically desirable, yet the rotting procedures with the known vegetation supports proceed too quickly, with the result that they become unusable after a relatively short time. This is particularly disadvantageous if, for logistical reasons, the vegetation support has to be stored prior to actual lining work for a relatively long period, the result of which can be that the vegetation support can no longer be picked up and rolled up for transporting, because of the advanced rotting process.
It has also been demonstrated that the support layer tends to shrink during prolonged dryness. This results in shrinkage by about 10 cm in width for a vegetation support width of 1 m, for example. When strips are laid side by side this leads to unacceptable gaps.
The object of the present invention is to produce a vegetation support of the type initially described, which can be manufactured easily and cost-effectively, which consists of a recyclable material insensitive to dry-shrinking with sufficient firmness and which decays as slowly as possible and in a controlled manner.
This task is solved by a vegetation support of the type described at the outset, which exhibits the characteristics of the distinguishing part of Claim 1. The vegetation support according to the present invention is characterised in that the fibres of the mat are coconut fibres and in that the security against loosening of the fibres from the mat is a plant-compatible binder material which is applied to the upper surfaces of at least one part of the fibres and by means of which the fibres of the mat are stuck to one another at least partially.
Through this process a vegetation support is produced in a surprisingly easy manner, whose mat forming the actual vegetation support is not secured by overlaid and underlaid formed fabrics, rather whose fibres of the mat are connected to one another by means of a plant-compatible binder. By means of this binder, which is, by way of advantage, a synthetic dispersion, latex, a bitumen emulsion, an adhesive, a resin or a wax, on the one hand the fibres of the mat are held together, and on the other hand the binder, in particular if it is applied to the underside of the mat, in accordance with an advantageous embodiment of the present invention, can absorb tensile forces originating from laying the vegetation support on inclined slopes.
The binder also guarantees, in particular when the majority of the fibres is cross-linked on its upper surfaces with the binder, that the rotting process of the mat proceeds relatively slowly. It could be advised that the normal rotting period lasted from around 3 to 12 years to around 12 to 18 years. In addition, it is due to the binder that the fibres, namely the coconut fibres, become insensitive to shrinkage brought about by dryness.
It is particularly preferred if the solvent is latex, which retards the advance of the rotting process of the fibres on the one hand, but on the other hand is fully decomposable
With respect to the drainage mat made of wood wool disclosed in DE 43 29 957 A1 it is known to cross-link the latter with latex and to stick down the wood-wool fibres. But such a mat is not suitable as vegetation support, since the cavities between the relatively broad wood-wool fibres are too wide to securely hold substrate and roots. In addition, wood wool rots very quickly. The same applies to a support layer made of wood wool for ready-made lawn known from DE 82 31 033 U2.
As already indicated, the binder can be applied to the upper surface of all fibres, that is, the binder is in this case distributed over the entire cross-section of the mat, or the binder can be applied to one side of the mat. In the latter case, only those fibres projecting on the underside of the mat are cross-linked with the binder. It has been demonstrated that it is sufficient to provide one side only, that is, the underside of the mat with the binder. This means then that not all fibres of the fibre bundle of the mat are cross-linked with the binder, which can in theory result in the fact that the fibres of the upper side of the mat could be loosened from the fibre bundle of the mat; however, it has been shown in practice that this danger is to be ignored. If the binder is applied very thickly to the underside, this effectively results in a relatively thick layer of the binder as a xe2x80x98solexe2x80x99 which can advantageously absorb any resulting tensile forces.
If it is a question of very high tensile forces, that is, in the case of strongly inclined surfaces, the underside of the mat can be provided with a formed fabric or a lattice fabric as additional security, which can then absorb the resulting tensile forces. With this arrangement, the binder can be advantageously used to stick the mat to the formed fabric or to the lattice fabrics In this case, any time-intensive and cost-intensive stepping or perforation can be dispensed with.
In a practical embodiment of the invention it is provided for inorganic fibres to be intermingled with the coconut fibres, on a mineral basis and/or made of synthetic, whenever desired for special application cases. By way of example, mineral wool fibres can be intermixed with the coconut fibres to increase fire safety of the vegetation support.
In a further embodiment of the present invention it is provided that the underside of the mat is attached to a sheet made of decayable synthetic. This type of relatively quickly rotting sheet can serve several purposes.
The sheet can, for instance, retain moisture in the vegetation support for a certain period. However, the sheet can also be used for preventing sowing material and unwanted plant parts from piercing through the bottom into the vegetation support, in particular when the vegetation support is laid on earth-bound surfaces, for example on street slopes. Using a normal, non-decaying sheet made of polyolefin would also be conceivable; such sheets would accumulate, however, as unwanted refuse on expiry of the normal serviceable life of the vegetation support, whereas decomposable sheets, constructed from starch products for instance, decay along with the mat of the vegetation support and are no threat to the environment.

Vegetation support consisting of a mat of entangled organic fibers


A carbamate-functional compound having a structure

This invention concerns carbamate-functional materials and curable coating compositions containing such materials, especially waterborne coating compositions containing such materials.
Carbamate-functional materials have found particular utility in coating compositions as crosslinkable resins. Curable coating compositions utilizing carbamate-functional resins are described, for example, in U.S. Pat. Nos. 5,693,724, 5,693,723, 5,639,828, 5,512,639, 5,508,379, 5,451,656, 5,356,669, 5,336,566, and 5,532,061, each of which is incorporated herein by reference. These coating compositions can provide significant advantages over other coating compositions, such as hydroxy-functional acrylic/melamine coating compositions. For example, the coatings produced using carbamate-functional resins typically have excellent resistance to environmental etch (also called acid etch). Environmental etch results in spots or marks on or in the coating that often cannot be rubbed out.
One drawback of coatings with carbamate-functional resins is that they tend to require more organic solvent to achieve acceptable viscosity and for application. Carbamate-functional materials prepared from an isocyanurate of a diisocyanate, for example, are generally advantageous as an additive resin or principal resin in a coating composition, but these materials increase the viscosity of the coating composition so that more solvent is required. Coatings with higher amounts of organic solvent produce more regulated emissions during application.
Aqueous coating compositions have gained prominence due to the regulations on organic emissions. Such coatings have tended to be water-sensitive, however, because of the presence of the hydrophilic groups used to disperse the binder resins or surfactants, such as polyether-based surfactants, that remain in the coating film as low molecular weight, hydrophilic materials.
It would be advantageous to provide a water-dispersible, carbamate-functional material for a coating composition that would not have water-sensitivity in a cured coating.
The invention provides a carbamate-functional compound that is water soluble and coating compositions, especially waterborne coating compositions, containing the carbamate-functional material. The invention further provide a coating prepared from the coating composition and a coated substrate, especially an automotive substrate, having the coating thereon.
The carbamate functional compound of the invention has a structure
in which each of R1, R2, and R3 is independently
wherein R is hydrogen, methyl, or ethyl.
The carbamate-functional compound of the invention is combined with a carbamate-reactive material to form the coating composition of the invention. The coating composition is applied to a substrate, especially to an automotive substrate, and cured to produce a coating. The coating is preferably the outermost coating on the substrate, particularly a clearcoat coating.
The xcex2-hydroxy carbamate compound of the invention may be prepared by reacting triglycidyl isocyanurate first with carbon dioxide to convert the oxirane groups to cyclic carbonate groups, and then with ammonia to convert the cyclic carbonate group to a xcex2-hydroxy carbamate group. Triglycidyl isocyanurate is commercially available or may be prepared by reaction of isocyanuric acid with an epihalohydrin, in particular epichlorohydrin. The reaction of the triglycidyl isocyanurate can be done at any pressure from atmospheric up to supercritical CO2 pressures, but is preferably under elevated pressure (e.g., 60-150 psi). The temperature for this reaction is preferably 60-150xc2x0 C. Useful catalysts include any that activate an oxirane ring, such as tertiary amine or quaternary salts (e.g., tetramethyl ammonium bromide), combinations of complex organotin halides and alkyl phosphonium halides (e.g., (CH3)3Snl, Bu4Snl, Bu4Pl, and (CH3)4Pl), potassium salts (e.g., K2CO3, Kl) preferably in combination with crown ethers, tin octoate, calcium octoate, and the like.
Cyclic carbonate groups can be converted to carbamate groups by reaction with ammonia, which ring-opens the cyclic carbonate to form a xcex2-hydroxy carbamate. The ammonia may be anhydrous ammonia or aqueous ammonia (i.e., NH4OH). The carbonate ring can open to produce either of the two isomeric structures shown above for the R1, R2, and R3 groups.
The xcex2-hydroxy carbamate compound is water soluble and is also soluble in polar organic solvents, such as tetrahydrofuran, alcohols such as methanol and ethanol, and glycol ether-based compounds such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.
The coating composition of the invention includes the xcex2-hydroxy carbamate compound and one or more crosslinkers or curing agents reactive with the carbamate compound. The coating composition may optionally include other compounds, resins, and/or polymers reactive with the crosslinker. The combination of the xcex2-hydroxy carbamate compound, the crosslinker, and (if present) the optional further compounds, resins, and/or polymers is referred to as the xe2x80x9cvehicle.xe2x80x9d
In preferred embodiments, the xcex2-hydroxy carbamate compound is at least about 5%, more preferably at least about 10%, and still more preferably at least about 15% by weight of the nonvolatile vehicle. It is also preferred for the xcex2-hydroxy carbamate compound to be up to about 30%, more preferably up to about 50%, and still more preferably up to about 70% by weight of the nonvolatile vehicle. The xcex2-hydroxy carbamate compound is preferably from about 10% to about 70%, more preferably from about 15% to about 60%, and still more preferably from about 20% to about 60% by weight of the nonvolatile vehicle.
Particularly useful crosslinkers include, without limitation, materials having active methylol or methylalkoxy groups, such as aminoplast crosslinking agents or phenol/formaldehyde adducts. Examples of preferred curing agent compounds include, without limitation, melamine formaldehyde crosslinkers, including monomeric or polymeric melamine resin and partially or fully alkylated melamine resin, urea resins, and methylol ureas such as urea formaldehyde resin, alkoxy ureas such as butylated urea formaldehyde resin. Another suitable crosslinking agent is tris(alkoxy carbonylamino) triazine (available from Cytec Industries under the trademark TACT). Other useful crosslinkers include, without limitation, polyisocyanates and blocked polyisocyanates, curing agents that have epoxide groups, amine groups, acid groups, siloxane groups, cyclic carbonate groups, and anhydride groups. The curing agent may be combinations of these, particularly combinations that include aminoplast crosslinking agents. At least one crosslinker with functionality reactive with active hydrogens of the xcex2-hydroxy carbamate compound is included. Aminoplast resins such as melamine formaldehyde resins or urea formaldehyde resins are especially preferred. Water-soluble aminoplast resins for aqueous coating compositions are known. These include high imino-content melamine formaldehyde resins and fully methoxylated melamine formaldehyde resins.
In preferred embodiments, the crosslinker is at least about 5%, more preferably at least about 10% by weight of the nonvolatile vehicle. It is also preferred for the crosslinker to be up to about 40%, more preferably up to about 30% by weight of the nonvolatile vehicle. The crosslinker is preferably from about 5% to about 40%, more preferably from about 10% to about 35%, and still more preferably from about 15% to about 35% by weight of the nonvolatile vehicle.
The coating composition may include further crosslinkable compounds, resin, and/or polymers, preferably those that have active hydrogen functionality. Examples of additional compounds, resins, and/or polymers that may optionally be included are other carbamate- or hydroxyl-functional materials, including acrylic polymers, polyurethanes, and polyesters.
The coating composition used in the practice of the invention may include a catalyst to enhance the cure reaction. For example, when aminoplast compounds, especially monomeric melamines, are used as a curing agent, a strong acid catalyst may be utilized to enhance the cure reaction. Such catalysts are well-known in the art and include, without limitation, p-toluene sulfonic acid, dinonylnaphthalene disulfonic acid, dodecylbenzenesulfonic acid, phenyl acid phosphate, monobutyl maleate, butyl phosphate, and hydroxy phosphate ester. Strong acid catalysts are often blocked, e.g. with an amine. Other catalysts that may be useful in the composition of the invention include Lewis acids, zinc salts, and tin salts.
Although aqueous coating compositions that are free of regulated volatile organic compounds are preferred, a solvent may optionally be utilized in the coating composition used in the practice of the present invention. In general, the solvent can be any organic solvent and/or water. In one preferred embodiment, the solvent is a polar organic solvent. More preferably, the solvent is selected from polar aliphatic solvents or polar aromatic solvents. Still more preferably, the solvent is a ketone, ester, acetate, aprotic amide, aprotic sulfoxide, aprotic amine, or a combination of any of these. Examples of useful solvents include, without limitation, methyl ethyl ketone, methyl isobutyl ketone, m-amyl acetate, ethylene glycol butyl ether-acetate, propylene glycol monomethyl ether acetate, xylene, N-methylpyrrolidone, blends of aromatic hydrocarbons, and mixtures of these. In another preferred embodiment, the solvent is water or a mixture of water with small amounts of co-solvents.
The coating composition according to the invention is preferably utilized in an automotive or industrial high-gloss coating and/or as the clearcoat of an automotive composite color-plus-clear coating. High-gloss coatings as used herein are coatings having a 20xc2x0 gloss (ASTM D523) or a DOI (ASTM E430) of at least 80.
The coating composition may also be formulated as a pigmented coating, such as for a basecoat coating or a primer coating. In this case, the coating composition further includes a pigment or filler material. The pigment may be any organic or inorganic compounds or colored materials, metallic or other inorganic flake materials such as pearlescent mica flake pigments or metallic flake pigments such as aluminum flake, and other materials of kind that the art normally includes in such coatings. Examples of typical fillers are talc and barytes. Pigments and other insoluble particulate compounds such as fillers are usually used in the composition in an amount of 1% to 100%, based on the total solid weight of binder components (i.e., a pigment-to-binder ratio of 0.1 to 1).
Additional agents, for example surfactants, stabilizers, wetting agents, rheology control agents, dispersing agents, adhesion promoters, UV absorbers, hindered amine light stabilizers, etc. may be incorporated into the coating composition. While such additives are well-known in the prior art, the amount used must be controlled to avoid adversely affecting the coating characteristics.
Coating compositions can be coated on the article by any of a number of techniques well-known in the art. These include, for example, spray coating, dip coating, roll coating, curtain coating, and the like. For automotive body panels, spray coating is preferred.
When the coating composition according to the invention is used as the clearcoat of a composite color-plus-clear coating, the pigmented basecoat composition may any of a number of types well-known in the art, and does not require explanation in detail herein. Polymers known in the art to be useful in basecoat compositions include acrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyds, and polysiloxanes. Preferred polymers include acrylics and polyurethanes. In one preferred embodiment of the invention, the basecoat composition also utilizes a carbamate-functional acrylic polymer. Basecoat polymers may be thermoplastic, but are preferably crosslinkable and comprise one or more type of crosslinkable functional groups. Such groups include, for example, hydroxy, isocyanate, amine, epoxy, acrylate, vinyl, silane, and acetoacetate groups. These groups may be masked or blocked in such a way so that they are unblocked and available for the crosslinking reaction under the desired curing conditions, generally elevated temperatures. Useful crosslinkable functional groups include hydroxy, epoxy, acid, anhydride, silane, and acetoacetate groups. Preferred crosslinkable functional groups include hydroxy functional groups and amino functional groups.
Basecoat polymers may be self-crosslinkable, or may require a separate crosslinking agent that is reactive with the functional groups of the polymer. When the polymer comprises hydroxy functional groups, for example, the crosslinking agent may be an aminoplast resin, isocyanate and blocked isocyanates (including isocyanurates), and acid or anhydride functional crosslinking agents.
The coating compositions described herein are preferably subjected to conditions so as to cure the coating layer. Although various methods of curing may be used, heat-curing is preferred. Generally, heat curing is effected by exposing the coated article to elevated temperatures provided primarily by radiative heat sources. Curing temperatures will vary depending on the particular blocking groups used in the cross-linking agents, however they generally range between 90xc2x0 C. and 180xc2x0 C. The first compounds according to the present invention are preferably reactive even at relatively low cure temperatures. Thus, in a preferred embodiment, the cure temperature is preferably between 115xc2x0 C. and 150xc2x0 C., and more preferably at temperatures between 115xc2x0 C. and 140xc2x0 C. for a blocked acid catalyzed system. For an unblocked acid catalyzed system, the cure temperature is preferably between 80xc2x0 C. and 100xc2x0 C. The curing time will vary depending on the particular components used, and physical parameters such as the thickness of the layers, however, typical curing times range from 15 to 60 minutes, and preferably 15-25 minutes for blocked acid catalyzed systems and 10-20 minutes for unblocked acid catalyzed systems.
The invention is further described in the following example. The examples are merely illustrative and do not in any way limit the scope of the invention as described and claimed. All parts are parts by weight unless otherwise noted.

Water- and organic-soluble carbamate material

Abstract: in which each of R1, R2, and R3 is carbamate-functional is water soluble. Coating compositions, especially waterborne coating compositions, include the carbamate-functional compound and one or more crosslinkers. The invention further provide a coating prepared from the coating composition and a coated substrate, especially an automotive substrate, having the coating thereon.