There is provided an implanted system and method for delivering subsonic mechanical waves to one or more selected patient areas, said areas including the patient""s heart and/or lungs. The mechanical waves are delivered for the purpose of treating fibrillation or like arrhythmias, for enhancing lung gas exchange, enhancing cardiac muscle fiber relaxation, and enhancing coronary perfusion. Mechanical waves are generated in a frequency range of about 1,100,000 Hz, and preferably 1-50,000 Hz. The waves may be delivered continuously for short or long time periods, or may be controlled in timing either with respect to detected portions of a patient""s heartbeat signal or in response to a detected event such as fibrillation. In one preferred embodiment, the implantable system includes a defibrillation shock generator and control for responding to a defibrillation event by first delivering a sequence of mechanical waves and then delivering an electrical defibrillation shock. In another embodiment, the system and method treat incipient fibrillation or arrhythmia by delivering mechanical waves of predetermined timing to the patient""s heart and/or lungs. In a specific embodiment, mechanical waves are delivered through an array of transducers to the patient""s atrial wall, to treat atrial fibrillation.

The system and method of this invention relate to systems for treating cardiac fibrillation and, in particular, for using transducers driven at frequencies below the ultrasound range for mechanical treatment of the heart and related target areas.
Delivery of electrical shocks has proven to be an effective and relatively safe means for defibrillation of the heart, or for treating various types of cardiac arrhythmias. Implantable defibrillators, cardioverters, and combined pacemaker/cardioverter/defibrillator devices have come into widespread use for treatment of various arrhythmias. As effective as these new devices and systems have been, there remain a number of areas where substantial development work is needed, in order to increase efficiency and reliability, and to deal with known adverse effects. Some of the known problem areas are those of tissue damage in the vicinity of the electrodes across which the shocks are delivered, and in the case of atrial defibrillation, the patient sensation of sharp pain which can be caused by over-stimulation of the phrenic nerve. Despite improvements in lead and electrode design, there remains an ongoing need to reduce the amount of energy delivered in a shock, both for purposes of preserving the battery energy in the implanted device and for the important purpose of reducing patient anxiety about receiving a shock.
One alternative approach to the area of defibrillation that has been considered but not given much development is using ultrasound for defibrillating. This involves delivering high energy ultrasound waves to the affected region, e.g., the atrium or ventricle. Unfortunately, this technique has thus far met with a low success rate, on the order of 30%, and has been seen to cause damage to the endothelium and to the cardiac muscle fibers. However, it is the basis of this invention that lower frequency mechanical agitation of the heart has a variety of potential beneficial effects which have not yet been successfully exploited, particularly in treating a fibrillating heart or a heart which is prone to fibrillation or other arrhythmias. Mechanical agitation of the heart, particularly at frequencies below about 50 kHz, can have a direct defibrillation effect, as well as other beneficial effects on the fibrillating heart. Mechanical agitation, or movement of the cardiac muscle with sufficient energy can change the conductive properties of the muscle, and thus change the loop gain and disrupt the circular conductive paths which had been responsible for the fibrillation or other arrhythmia. Likewise, mechanical agitation may affect action potential duration of myocardial cells, and thus aid in termination of fibrillation. Mechanical agitation directed to the cardiac muscle may facilitate muscle fiber relaxation, and help bring the fibers into diastole. This, in turn, can reduce the threshold for electrical defibrillation. Similarly, mechanical treatment may be used to improve cardiac perfusion. It is known that perfusion of the myocardium is limited to the diastolic phase, and that during fibrillation perfusion stops even though the aortic pressure remains high for a few seconds. Application of low frequency mechanical waves to the myocardium can have a relaxing effect which improves perfusion, as well as a direct massaging effect which aids perfusion.
In addition to direct mechanical treatment of the heart, mechanical vibration of the lungs may also be used to treat a fibrillation problem. Low frequency vibration is known to improve gas exchange in the lungs. Since oxygen supply and carbon dioxide are critical in a fibrillation condition, such mechanical vibration to provide enhanced gas exchange in the lungs is supportive of and beneficial to defibrillation. Further, depending upon the precise effects of the low frequency waves at the air-tissue interface in the lungs, such waves may have the property of stimulating the pulmonary stretch receptors. This will, via the cardio-pulmonary reflex, result in parasympathetic output (n.Vagus) in the heart and contribute to suppressing fibrillation. In view of these considerations, it is seen that there is substantial potential for therapeutic application of implantable low frequency mechanical wave devices for treating arrhythmias, particularly fibrillation and transient ischemic heart disease.
It is an overall object of this invention to provide a system and method for utilizing mechanical waves for treating a cardiac condition such as fibrillation by delivering the low frequency waves to at least a part of the patient""s area comprising the heart and lungs, the mechanical wave treatment being utilized either alone or in combination with electric shock therapy.
In accordance with the above object, there is provided an implantable system and method for treating cardiac fibrillation and like conditions, involving delivery of mechanical waves to the patient""s heart and/or lungs, the waves being in a frequency range of about 1-50,000 Hz and being generated by one or more transducers positioned within the patient""s body for delivery of the waves to the target patient area. For example, the system may comprise a lead with a plurality of transducers adapted for positioning in the patient""s atrium, and for mechanically treating the atrium. In another embodiment, the waves are directly transmitted to the outside surface of the patient""s heart. Alternately, one or more wave transducers driven by the mechanical wave generator or generators may be positioned for delivering waves to the patient""s lungs, or to portions of the lungs and the heart. The implantable system includes sensing electrodes for sensing the patient""s natural cardiac activity, as well as cardiac responses to stimulation, and for controlling the wave treatments to be delivered at timed intervals with respect to the patient""s cardiac signals and/or in timed relation to generated defibrillation or cardiac pulses delivered to the patient.
The invention thus embodies a system and method for providing mechanical treatment alone, or coordinating mechanical treatment of the patient""s heart and/or lungs with defibrillation shock treatment delivered by a defibrillation pulse generator housed within the implanted system. The implanted system preferably has detection means for analyzing the patient history, detecting the timing and nature of arrhythmias, and for selecting an appropriate treatment in the form of a selected combination of mechanical wave treatment and defibrillation/cardioversion shock treatment.


A composition useful for making a coated optical fiber wherein the composition comprises a photocurable or E-beam curable composition having an alkoxysilane functionality attached through a long backbone.

The present invention relates to curable materials which are derived from (meth)acrylates and alkoxy-substituted organosilanes. A compound containing an alkoxy-substituted organosilane group is covalently attached to a relatively long molecule that has (meth)acrylate functionality. As part of a photo-curable formulation, this long chain provides improved adhesion to glass substrates by covalently tying the polymeric network to the glass substrate.
Photo-curing formulations used as coatings for glass optical fibers typically contain adhesion promoters to improve the adhesion between the polymer layer and the glass substrate. The most common kind of adhesion promoters (also known as coupling agents) consists of alkoxy-substituted organosilanes that have another reactive group capable of reacting with the polymerizable coating (Plueddemann, xe2x80x9cSilane Coupling Agentsxe2x80x9d, Plenum, 1982). The alkoxysilane group can react with Sixe2x80x94OH groups present on the glass surface. Thus, the coupling agent provides a covalent linkage between the glass surface and the polymeric coating. U.S. Pat. No. 5,146,531 discloses several suitable organofunctional silanes for use in optical fiber coatings, such as amino-functional silanes, mercapto-functional silanes, methacrylate-functional silanes, acrylamido-functional silanes, allyl-functional silanes, vinyl-functional silanes and acrylate-functional silanes. These silanes are preferably methoxy- or ethoxy-substituted. Some preferred organofunctional silanes include 3 aminopropyltriethoxysilane, 3-methacryloxypropyltrimetoxysilane, 3-mercaptopropyl trimethoxysilane, and 3-mercaptopropyltriehtoxysilane. WO 91/03503 and U.S. Pat. No. 4,849,462 disclose the use of mercaptan-functional alkoxysilanes as preferred adhesion promoters (e.g. 3-mercaptopropyl trimethoxysilane, also known as xcex3-mercaptopropyl trimethoxysilane).
The adhesion promoter is typically added to the photo-curable formulation (usually a mixture of acrylate monomers and oligomers) in amounts from about 0.1% by weight to about 5% by weight. During radiation exposure, the adhesion promoter reacts with the polymerizing mixture, getting incorporated into the polymer network. After radiation exposure the adhesion promoter molecules are tied to the polymer network. Only a small percent of these tied adhesion promoter molecules are close enough to the glass surface to react with it. Thus, the vast majority of adhesion promoter molecules are ineffective because they cannot reach the glass since they are constrained by being attached to the polymer network.
It is an object of the present invention to provide a method to improve the adhesion of photo-curable coatings to glass.
The present invention comprises covalently attaching an alkoxysilane molecule to a relatively long molecule that is part of a photo-curable formulation and that can copolymerize with this formulation upon photo-irradiation. After the long molecule reacts through radiation exposure, the alkoxysilane functionalities are tied to the network through the relatively long backbone. The long length of this backbone gives the alkoxysilane groups a higher probability to reach and react with the glass surface as compared to traditional adhesion promoters that are randomly linked to the polymer network.
The present invention more specifically relates to a method to improve the adhesion of photo-curable polymeric coatings to glass substrates such as glass optical fibers by using a more effective adhesion promoter. It should be noted that the present compositions are used as coatings for glass substrates such as fibers and the term coating where appropriate encompasses but does not exclusively include cladding of glass fibers. In the case of a cladding, the coating has a lower refractive index than the (glass) fiber and can therefore be used as a cladding in the optical sense to guide electromagnetic wave energy within the fiber.
Photo-curable coatings for optical fibers generally comprise a (meth)acrylated oligomer, one or more (meth)acrylate monomers, optionally other monomers that can copolymerize with (meth)acrylates, a photoinitiator, and other additives. The present invention comprises the use of an adhesion promoter with the following formula:
(X)mxe2x80x94Rxe2x80x94[xe2x80x94(Y)sxe2x80x94Si(OR1)n(R2)3-n]p
where X contains a functional group capable of reacting with a (meth)acrylate group; R is a relatively long chain radical whose molecular weight is at least 500; Y is an atom or group of atoms whose structure depends on the chemistry used to attach Si to R; R1 and R2 are independently Alkyl groups; mxe2x89xa71, nxe2x89xa71, pxe2x89xa71, and s can be 0 or 1.
The preferred structure of X contains a (meth)acrylate group:
[xe2x80x94Cq(R3)(R4)xe2x80x94Oxe2x80x94]rC(O)xe2x80x94C(R5)xe2x95x90CH2
wherein R3, R4, and R5 are independently hydrogen, methyl, ethyl or propyl, q is an integer from 1 to 10, r is either zero or an integer from 1 to 10. A specific example of a preferred X is
xe2x80x94CH2xe2x80x94CH2xe2x80x94Oxe2x80x94C(O)xe2x80x94CHxe2x95x90CH2
Other examples of adequate structures for X include, for example, ethylenically unsaturated groups, such as vinyl and allyl functionalities.
R1 is preferably a methyl or an ethyl group, R2 is preferably a methyl or an ethyl group, and n is preferably 3. The preferred values for m and p are 1.
There is no special requirement as to the chemical nature of R, as long it is compatible with the photo-curing formulation and it does not interfere with the curing reaction. Its preferred molecular weight is at least 1,500. A preferred structure of R is
xe2x80x94Oxe2x80x94C(O)xe2x80x94NHxe2x80x94R6xe2x80x94NHxe2x80x94Cxe2x80x94(O)xe2x80x94R7xe2x80x94C(O)xe2x80x94NHxe2x80x94R8xe2x80x94NHxe2x80x94C(O)
wherein R6 and R8 are independently linear, branched or cyclic alkylene of from six to twenty carbon atoms that may or may not contain aromatic rings. Some exemplary structures of R7 include perfluoropolyethers such as
O(CH2CH2O)n1(CF2CF2O)p1(CF2O)q1(CH2CH2O)n1
O(CH2CH2O)n1CH2CF2O(CF2CF2O)p1(CF2O)q1CF2CH2O(CH2CH2O)n1
O CH2CF2O(CF2CF2O)p1(CF2O)q1CF2CH2O
{OCH2CF(CF3)O[CF(CF3)CF2O]2C2F4}2
O CH2CH(OH)CH2OCH2CF2O(CF2CF2O)p1(CF2O)q1CF2CH2CH(OH)CH2O
wherein
0xe2x89xa6n1xe2x89xa65, 0.2xe2x89xa6p1/c1xe2x89xa65
and the actual values of p1 and q1 are such that the molecular weight of the fluorinated diol is between 500 and 10,000 and wherein the repeating fluorinated ether groups maybe random or block repeating units polyethers, such as
xe2x80x94Oxe2x80x94(CH2xe2x80x94CH2xe2x80x94O)r11xe2x80x94
xe2x80x94Oxe2x80x94[CH(CH3)xe2x80x94CH2xe2x80x94O]r11xe2x80x94
xe2x80x94Oxe2x80x94(CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94O)r11xe2x80x94;
polyesters, such as
xe2x80x94Oxe2x80x94[R9Oxe2x80x94C(O)xe2x80x94R10xe2x80x94C(O)xe2x80x94O]p11xe2x80x94R9xe2x80x94Oxe2x80x94;
polycarbonates such as
xe2x80x94Oxe2x80x94[R11xe2x80x94Oxe2x80x94C(O)xe2x80x94O]r11;
or end-capped hydrocarbon chains, such as
xe2x80x94Oxe2x80x94R12xe2x80x94Oxe2x80x94
In the preceding structures, R9, R10 and R11 are independently linear, branched or cyclic alkylene of from six to twenty carbon atoms that may or may not contain aromatic rings. R12 is a linear or branched hydrocarbon chain that may or may not contain unsaturated bonds, and whose molecular weight is at least 500, and preferably at least 1,500. The value of r11 in the preceding structures is such that the molecular weight of R7 is at least 500, preferably at least 1,500.
The structure of Y depends on the structure of the silane starting material and the chemical reaction used to attach it to the pre-polymer R. A general structure of Y that can be used with the R structure shown previously is
xe2x80x94NHxe2x80x94R13xe2x80x94
where R13 is an alkylene chain. A preferred structure for R13 is xe2x80x94[CH2]3xe2x80x94.
Alternately, the structure of Y could be chosen to be
xe2x80x94C(O)xe2x80x94NHxe2x80x94R13xe2x80x94
in which casexe2x80x94the structure of R mentioned earlier would be replaced by the following structure
xe2x80x94Oxe2x80x94C (O)xe2x80x94NHxe2x80x94R6xe2x80x94NHxe2x80x94C(O)xe2x80x94R7xe2x80x94
Yet another possibility is for the value of s in the adhesion promoter molecule to be zero. In this case, the structure of R would be either
R7[xe2x80x94Cq(R3)(R4)xe2x80x94O]rxe2x80x94C(O)xe2x80x94C(H)(R5)CH2xe2x80x94
or
xe2x80x94Oxe2x80x94C(O)xe2x80x94NHxe2x80x94R6xe2x80x94NHxe2x80x94C(O)R7xe2x80x94C(O)xe2x80x94NHxe2x80x94R8xe2x80x94NHxe2x80x94C(O)xe2x80x94Oxe2x80x94[xe2x80x94Cq(R3)(R4)xe2x80x94Oxe2x80x94]rC(O)xe2x80x94C(H)(R5)xe2x80x94CH2xe2x80x94
The most convenient way to ensure that R is compatible with the photo-curable formulation is to use the same backbone as the component with the largest molecular weight in this formulation (i.e. the urethane oligomer). Using this same backbone is also desirable because the synthesis is more convenient.
An example of one possible way to synthesize such a long-chain adhesion promoter can be described as follows. The starting point is an xcex1,xcfx89-dihydroxy oligomer. This material is reacted with a di-isocyanate, obtaining an isocyanate endcapped oligomer. This oligomer in turn can react with a hydroxy functional (meth)acrylate and an amine-functional alkyloxysilane, thus yielding an oligomer molecule with an alkoxysilane group on one end and a (meth)acrylate group on the other end. The reactions employed in this scheme are the well-known isocyanate-hydroxyl reaction to yield a urethane group, and the isocyanate-amine reaction to yield a urea group. These reactions are typically carried out using a tin catalyst such as dibutyltin dilaurate. An alternate way to carry out this procedure is to react first the hydroxy-functional (meth)acrylate with the di-isocyanate to obtain an isocyanate-functional (meth)acrylate. Similarly, the aminosilane can be reacted first with the di-isocyanate to obtain an isocyanate-functional alkoxysilane. Alternately one can use a commercially available isocyanate-functional alkoxysilane. These isocyanate-functional groups can then react with an xcex1,xcfx89-dihidroxy oligomer, to obtain an oligomer with both (meth)acrylate and alkoxysilane functionality.
The advantage of the above procedures is that they parallel the synthesis of acrylated urethane oligomers as disclosed for example in WO 91/03503. Thus an economic way to produce these long chain adhesion promoters is to incorporate their synthesis as part of the acrylated urethane synthesis. The following examples illustrate the synthesis of an acrylated urethane oligomer, as well as the synthesis of an oligomeric adhesion promoter.
The present invention also relates to a method in which an appropriately functional alkoxysilane is incorporated in the synthesis of the di (or poly)-functional (meth)acrylated oligomer in amounts from 0.1 to 50% mole of reactive groups. Specifically, this means when a di(meth)acrylated oligomer is synthesized using the general scheme
F-R-F+2A-Xxe2x86x92A-X-F-R-F-X-A
or with a similar scheme with intermediate steps:
E-R-E+2G-R2-Gxe2x86x92G-R2-G-E-R-E-G-R2-G
G-R2-G-E-R-E-G-R2-G+2A-Xxe2x86x92A-X-G-R2-G-E-R-E-G-R2-G-X-A
then an alkoxysilane-containing molecule with a functional group that can react with E, F, G, or a can be incorporated into the synthesis of the di-(meth)acrylated oligomer to produce a mixture containing di-(meth)acrylated oligomer, and oligomers that have both (meth)acrylate and alkoxysilane functionalities. In the above schemes, R is a prepolymer with functional groups F, or functional groups E, A is a (meth)acrylate group connected to a functional group X than can react with F, and G is a functional group that can react with E.
The present invention will be illustrated by the following non-limiting examples. It is understood that the examples are non-limiting and are capable of variation and modification. The invention is not limited to the precise details set forth in the examples.
A 200 ml flask was oven dried, evacuated, and filled with Argon (Ar), to which isooctyl acrylate (25 ml), 0.02 weight percent of butylated hydroxytoluene inhibitor (BHT, 0.0464 g in isooctyl acrylate) and isophorone diisocyanate (19.5 g, 0.044 mol) were added. An infrared (IR) spectrum was taken. The temperature of the reaction flask was raised to 40xc2x0 C. and maintained by a temperature controller. 0.05 weight percent of dibutyltin dilaurate catalyst (0.116 g in isooctyl acrylate) was added. 4-Hydroxybutyl acrylate (12.6 g, 0.088 mol) was dripped in over 15-20 minutes. After two hours, an IR spectrum was taken to confirm loss of half the isocyanate peak (2260 cmxe2x88x921). 4000 MW polypropylene glycol (PPG, 175 g, 0.044 mol) was introduced, and the temperature was raised to 70xc2x0 C. The endpoint of the reaction was confirmed by IR.
A hundred ml three neck flask was oven dried, evacuated, and backfilled with Ar, Isooctyl acrylate (solvent, 20 ml), and isophorone diisocyanate (4.45 g, 0.02 mol) were introduced and an IR spectrum was taken. The temperature of the reaction flask within a heating mantle was raised to 65xc2x0 C. and maintained with a temperature controller. 0.05 weight percent of dibutylin dilaurate (catalyst) was introduced (0.024 g in isooctyl acrylate). With increased Ar flow, the septum was removed, polypropylene glycol (PPG, MW≈4,000, 40 g 0.01 mol) was added with a large bore syringe without a needle, and the septum was replaced (4000 MW PPG was too viscous to inject through the needle). After two hours reaction time a spectrum was taken, and other spectra were taken at intervals until half the isocyanate peak (2260 cmxe2x88x921) remained. 0.2 weight percent butylated hydroxytoluene inhibitor (BHT, 0.0095 g. in isooctyl acrylate) was added, and 4-hydroxybutyl acrylate was dripped in over 15-20 minutes. After an additional hour, the reaction was monitored by IR until half the remaining isocyanate was consumed. 3-Aminopropyltrimethoxysilane (1.79 g, 0.01 mol) was introduced, and the endpoint of the reaction verified by IR.
The synthesis in the above examples is facilitated by the fact that the two isocyanate groups in the isophorone diisocyanate molecule have different reactivities (one of them is attached to a cycloaliphatic secondary carbon, while the other one is attached to an aliphatic primary carbon). The different reactivities prevent the isocyanate from forming a linear polymer with the diol in the first step of Example 2. Similarly, the different reactivities ensure that only one isocyanate per molecule reacts with hydroxybutyl acrylate in Example 1.
In order to test the dependence of the oligomeric adhesion promoter effectiveness on the length of the oligomer backbone, a series of oligomeric adhesion promoters with varying backbone molecular weights was prepared, following Example 2. UV-curable formulations similar to optical fiber primary coatings were prepared using these oligomeric adhesion promoters (OAP). The mole fraction of trimethoxysilane groups was held constant in all adhesion promoter-containing formulations. The oligomeric acrylated urethane (from Example 1, referred to as xe2x80x9coligomerxe2x80x9d) and OAP together made up 50 wt. % of the formulation, ensuring a constant PPG concentration in all formulations. The generalized formulation is given in Table 1.
In order to maintain a constant molarity of trimethoxysilane and at the same time a constant weight fraction of overall PPG, it is necessary to change the relative amounts of oligomer and adhesion promoter as the molecular weight of the latter varied (Table 2).
Films (6 mils thick) with the above compositions were drawn on thoroughly cleaned Pyrex plates. All films were cured at a dose of 1xc2x10.03 J/cm2.
Peel Tests. Strips of 0.25 inch adhesive backed copper tape were laid down on the UV-cured film described above, with cuts made on each side of the tape to isolate 0.25 inch wide sections of film for testing. 90 degree peel testing was performed under ambient conditions at a rate of approximately one inch per minute. Data were plotted and peel force values determined from the resulting curves. The following table indicates the measured peel force values as a function of the molecular weight of the PPG precursor used to make each OAP.
The results in Table 3 show that the long adhesion promoter molecules are considerably more effective than the shorter ones. In fact the adhesion in the 2,000 and 4,000 molecular weight cases was so strong that the films broke before peeling (cohesive failure).
In order to corroborate that the improved adhesion seen in Example 3 for the OAPs containing PPG backbones of MWxe2x89xa72,000 was indeed due to the trimethoxysilane functionality attached to the oligomer chain, a series of xe2x80x9cmockxe2x80x9d oligomeric adhesion promoters was synthesized. The synthesis follows Example 2, except that n-hexyl amine was used instead of aminopropyltrimethoxysilane. Thus, the resulting product had a structure exactly like that of the OAP, except that one end of the chain consisted of a hexyl group instead of a trimethoxysilane group. Adhesion measurements with formulations containing these xe2x80x9cmockxe2x80x9d OAPs were carried out as in Example 3. The adhesion values for the mock OAPs based on the 4,000 and 2,000 MW PPG precursor were 40 and 32 g/in, respectively. These values are an order of magnitude lower than those obtain with the real OAPS.
Since the reactive end-groups of the prepolymers used as reagents in the syntheses described above usually have equal reactivities, the product will not be pure; it will be a in a statistical mixture containing about 50% of the desired oligomeric adhesion promoter, 25% of diacrylated oligomer, and 25% of an oligomer end-capped on both ends with an organosilane. It is possible, however, to minimize the formation of the latter by-product by choosing the appropriate conditions to synthesize the oligomeric adhesion promoter. The preferred means to do this is to incorporate the synthesis of the oligomeric adhesion promoter into the synthesis of the diacrylated oligomer that will ultimately be used in the final coating formulation. One common way to synthesize the diacrylated oligomer consists of reacting one molecule of prepolymer diol with two molecules of di-isocyanate to form an isocyanate-endcapped prepolymer. This molecule, in turn, is reacted with two molecules of a hydroxyfunctional acrylate to form a diacrylated oligomer. A slight modification of this process can produce the diacrylated oligomer mixed with the right amount of oligomeric adhesion promoter. Starting with the isocyanate-endcapped prepolymer, one can add a small amount of, for example, aminopropyltrimethoxysilane. This can be from 0.1 to 20 mol % of the isocyanate groups. The amine group reacts with the isocyanate group, thus obtaining a prepolymer with alkoxysilane functionality. Since there is a large excess of isocyanate groups, there is little chance that two aminopropyltrimethoxysilane molecules will end up attached to the same prepolymer molecule. The balance of the isocyanate groups can be reacted with, for example, hydroxyethyl acrylate. The product will be a mixture of diacrylated oligomer, oligomeric adhesion promoter (i.e. oligomer molecules that have an acrylate on one end and an alkoxysilane group on the other end), and oligomer endcapped with alkoxysilanes on both ends. However, as opposed to Example 2, in this case the statistics favors the formation of the oligomeric adhesion promoter over the last by-product.
The product distribution is described by a binomial distribution. Thus, if for every mole of isocyanate end groups in the isocyanate-endcapped prepolymer there are x moles of aminopropyltrimethoxysilane, the relative amounts of products will be as follows:
For example, if the isocyanate-terminated oligomer is reacted with 10% equivalents of aminopropyltrimethoxysilane, and 90% equivalents of hydroxyethyl acrylate, the distribution will be
Thus, in the same process one can make the oligomer already mixed with oligomeric adhesion promoter, with a very small amount of by-product.
Equivalent results can be obtained by reacting a hydroxy-functional acrylate with a di-isocyanate first to form an isocyanate-functional acrylate, and either using an isocyanate-functional alkoxysilane, or making one by reacting an amino-functional silane with a di-isocyanate. The isocyanate-functional alkoxysilane and the isocyanate functional acrylate are then reacted with a hydroxyl-functional prepolymer (with a large excess of hydroxyl groups over isocyanate-functional alkoxysilane). The product distribution can be described by a binomial distribution as explained above.
96.14 g isophorone di-isocyanate was mixed with 0.09 g BHT (polymerization inhibitor) and 0.291 g dibutyltin dilaurate (catalyst) in 100 ml ethylhexyl acrylate (solvent). The mixture was heated to 45xc2x0 C. under dry air. Then, 50.25 g hydroxyethyl acrylate was added gradually with a syringe through a septum. The addition was carried out during a 2 hour period under dry air. The reaction was followed with infrared spectroscopy until half of the NCO groups were consumed. The resulting product was an isocyanate-functional acrylate dissolved in ethylhexyl acrylate.
28.52 g of xcex1,xcfx89-dihydroxypoly(tetramethylene oxide) (Terathane 2,000; number average molecular weight 2,045) was mixed with 15.086 g of the product from Example 5. The mixture was heated to 70xc2x0 C. and allowed to react overnight under dry air. All the NCO groups were consumed. The resulting product is a poly(tetramethyleneoxide) urethane diacrylate.
74.11 g (0.33 moles) of isophorone di-isocyanate was mixed with 65.83 g of ethylhexyl acrylate (solvent), 0.09 g BHT (polymerization inhibitor) and 0.21 ml of dibutyltindilaurate. 6 g (0.033 moles) of aminopropyltrimethoxysilane was added over 15 minutes under dry air at 45xc2x0 C. The disappearance of the NH2 doublet was followed with infrared spectroscopy. 34.8 g (0.2999 moles) of hydroxyethyl acrylate was added to the mixture and reacted at 55xc2x0 C. for two hours. The resulting product consisted of a mixture of approximately 90 mole % of isocyanate-functional acrylate, and 10 mole % of isocyanate-functional trimethoxysilane dissolved in ethylhexylacrylate.
55.09 g of xcex1,xcfx89-dihydroxypoly(tetramethyleneoxide) (Terathane 2,000, MW=2,045) was reacted with 29 g of the product from Example 7 at 70xc2x0 C. under dry air. The reaction was carried out overnight until all the NCO groups were consumed. The resulting product consisted of a mixture of about 81 mole % diacrylated urethane oligomer and 18 mole % of an oligomer endcapped with an acrylate on one end and a trimethoxysilane on the other end.
A UV-curable formulation containing the product from Example 8 as well as several control formulations were prepared:
Formulation A was used as a control without adhesion promoter. Formulations C and D contain standard commercial adhesion promoters. Formulations B, C and D contain 0.0041, 0.0051, and 0.0043 moles of trimethoxysilane per 100 g of formulation, respectively.
Glass microscope slides were cleaned in a concentrated sulfuric acid/nitric acid solution (5% nitric acid), rinsed with deionized water, and air-dried. Films of the above formulations were drawn on the glass slides with a doctor blade (10 mil film thickness), and the films were cured using a dose of 2 J/cm2. Adhesion was measured using a 90xc2x0 peel test at 5 in/min on samples aged under different conditions.
The adhesion of the formulation containing the oligomeric adhesion promoter from the instantaneous invention is more than twice stronger than which can be achieved using equivalent silane molar amounts of commercial adhesion promoters.
This invention is not limited to using isocyanate chemistry to synthesize the adhesion promoter molecule. Any chemical reaction that can be used to attach an alkoxysilane group to one end of a long chain and a (meth)acrylate to the other end of the chain can give an effective adhesion promoter. For example, epoxy-functional prepolymers are typically reacted with acrylic acid to yield acrylated oligomers. Since amines react easily with epoxides, an amine-functional alkoxysilane could be incorporated into the oligomer as described above. Another attractive way to synthesize oligomeric adhesion promoters is to attach directly an alkoxysilane functionality to a diacrylated oligomer. This can be done via a hydrosilylation reaction: a silicon hydride can add directly to the ethylenic unsaturation of the acrylate group using transition metal catalysts such as platinum:
R14SiH+CH2xe2x95x90CHxe2x80x94C(O)xe2x80x94xe2x86x92R14Sixe2x80x94CH2xe2x80x94CH2xe2x80x94C(O)xe2x80x94
Thus, a diacrylated oligomer can be reacted with a small amount of, for example, trimethoxysilane, to give a product of the form
CH2xe2x95x90CHxe2x80x94C(O)xe2x80x94Oxe2x80x94R15xe2x80x94Oxe2x80x94C(O)xe2x80x94CH2xe2x80x94CH2xe2x80x94Si(OCH3)3
Since there is a large excess of acrylates over silicon hydride groups, the formation of the above molecule will be favored over a molecule with trimethoxysilane groups on both ends.

Curable coatings with improved adhesion to glass


A method for cleaning polyethylene terephthalate containers including contacting the PET container with an alkaline wash solution having a temperature ranging of less than about 60xc2x0 C. is disclosed. The alkaline wash solution is formulated from a first concentrate, a second concentrate, an alkalinity source, and a balance of water. The first concentrate preferably has a first nonionic surfactant, a first builder, and acid in an amount effective to provide a phase stable solution. The second concentrate preferably has a second nonionic surfactant and a second builder. The first and second concentrate are present in the wash solution in a concentration ranging from about 0.3 wt. % to 2.0 wt. %. Preferably, the first nonionic surfactant has a cloud point ranging from about 5xc2x0 C. to 60xc2x0 C.

The invention relates generally to methods and compositions for cleaning polyethylene terephthalate containers. More specifically, the invention relates to methods and compositions which remove mold, present on polyethylene terephthalate containers, with reduced hazing.
As with many industries, the drive towards economy has also effected the beverage industry and has resulted in certain real changes in the way in which beverages are bottled, distributed and dispensed. In the last decade the beverage industry has seen a switch from glass to plastic containers. Plastic containers may be made from any number of materials depending on the application. One material is polyethylene terephthalate, xe2x80x9cPETxe2x80x9d. Two types of PET bottles that are commonly used are single trip and multi-trip bottles. Single trip bottles are those which are filled, used, and then discarded. Multi-trip bottles are collected and reused and must be washed before refilling.
PET bottles offer several advantages over glass. Their light weight reduces freight costs. When dropped onto a hard surface they do not shatter like glass and generally do not break. Conveyor wear caused by the containers in the packaging plant is also reduced. The closure is also generally reusable after a bottle has been opened.
Disadvantages are that PET bottles are easily scratched, and susceptible to chemical attack when they are washed. PET containers also do not tolerate conditions above 60xc2x0 C. Exposing them to higher temperatures than 60xc2x0 C. causes deformation and/or shrinkage of the bottles.
Recycling of PET containers was recently approved by the FDA in the USA to permit turning used containers into new ones. Because new resin costs 50 to 75 cents per pound, recycling used bottles is economically attractive. In time, glass soft drink bottles are expected to disappear from the market. This heightens the relevance of PET container processing even further.
The cleaning of PET bottles takes place over a series of steps using caustic immersion tanks and spray wash stages in a bottlewasher. In the wash tanks, product residue, dirt, labels and labeling adhesive are removed. Because the surface of PET bottles is hydrophobic, cleaning them is more difficult than glass bottles. Also, the lower washing temperature decreases the chemical activity of the bottlewashing solution.
Two principle problems in the cleaning of PET bottles are touched on by Laufenberg et al., xe2x80x9cCleaning, Disinfecting, and Transporting Pet Returnablesxe2x80x9d, Brew Bev. Ind. Int. 1, 40-4 (0 ref.) January, 1992.
In this article, the author outlines the susceptibility of the PET bottles to corrosion or hazing. Hazing results from the chemical etching of the surface of the PET container by the caustic present in the wash bath.
An especially challenging problem which affects reusable PET bottles is the occurrence of mold in returned bottles. To simply discard all bottles from which mold can not be removed is prohibitively expensive. Reject rates of 40 to 50% have occurred at certain times of the year in countries located in tropical climates.
The necessary cleaning temperature for PET bottles is 60xc2x0 C. or less due to the glass transition temperature of PET. If exceeded, PET bottles deform and shrink. The cleaning power of a bottlewashing solution at 60xc2x0 C. is only one quarter that at 80xc2x0 C. Bottles returned with product residue, i.e., those bottles that have not been rinsed, are almost always contaminated with microbiological forms of life. The bottle washing solution eliminates the presence of microbiological forms of life such as bacteria, spores, molds, and yeasts present in the bottle. However, at the reduced temperature of 60xc2x0 C., molds often present a persistent problem in the cleaning and reuse of PET bottles.
PET bottles simply cannot be washed like glass. Glass bottles are normally washed at 80xc2x0 C. Glass can also be washed with a relatively high concentration of caustic. While glass may be washed with up to 5.0% caustic, as little as 1.5% caustic can cause hazing in a PET container. With glass the washing temperature, the caustic concentration, and the washing time may be adjusted to allow for variability within the environment. In contrast, PET containers cannot withstand high levels of any of these variables.
While various alternatives have been proposed such as lowering the level of caustic, there remains a need in the industry for compositions and methods which allow for the efficient cleaning of PET containers and multiple reuse events.
The first aspect of the invention is a method for cleaning a polyethylene terephthalate container. The method includes combining a first concentrate with a second concentrate in an alkaline wash solution. The first concentrate includes from about 0.3 to 25 wt-% of a surfactant and from about 5 to 30 wt-% of an acid. The second concentrate includes from about 8 to 60 wt-% of a builder. The method further includes the step of contacting the PET container with the wash solution wherein the removal of soil is undertaken with minimal hazing of the container.
An additional aspect of the invention is a method for cleaning polyethulene terephihalate containers which includes contacting the container with an alkaline wash solution having a temperature ranging from about 50xc2x0 C. to 60xc2x0 C. The alkaline wash solution is formulated from a first concentrate, a second concentrate, an alkalinity source, and a balance of water. The first concentrate includes a nonionic surfactant, a first builder, and acid in an amount effective to provide a phase stable solution. The second concentrate includes a nonionic surfactant and a second builder. The first and second concentrate are present in the wash solution in a concentration ranging from about 0.5 wt-% to 1.2 wt-%, and the first nonionic surfactant has a cloud point ranging from about 5xc2x0 C. to 60xc2x0 C.
A further aspect of the invention is an alkaline wash solution for cleaning polyethylene terephthalate bottles. The wash solution includes from about 1 to 5 wt-% of a source of alkalinity, from about 480 to 4000 ppm of a builder, from about 6 to 500 ppm of a surfactant, and from about 20 to 800 ppm of a coupler.
The invention is compositions and methods for cleaning polyethylene terephthalate (PET) bottles with enhanced removal of mold and reduced hazing. In addition to the 1 to 3 wt-% caustic commonly used in PET bottle washing procedures, the compositions of the invention include surfactants and builder combination, which heightens cleaning and removes mold.
Hazing generally results from chemical etching caused by caustic present in the wash solution. Hazing is a clouding or dulling of the PET container surface which detracts from the aesthetic character of the container. Surprisingly, it has been found that by using surfactants with appropriate cloud points, hazing may be substantially reduced. Preferably, PET containers treated with the wash solution of the invention are substantially free of hazing.
Further, mold growth, particularly in the inside of returned PET bottles, proves to be a major challenge in bottle washing. Molds are very difficult to remove, even with a solution having as much as 3% caustic. Good cleaning usually removes most of the organic components of mold. However, the inorganic residues of mold may remain on the PET container surface. This may cause a problem similar to water spots. This condition gives a positive test result by methylene blue staining, (Industrial Code of Practice for Refillable PET Bottles, Edition 1 (1993-1994 UNESDA/CESDA, pg. V-18). The compositions and methods of the invention substantially remove soils and both the organic and inorganic residues of mold.
Generally, the wash solution of the invention is formulated from two concentrate compositions. These two concentrate compositions are combined in an aqueous wash solution with an alkalinity source, before use. These concentrate compositions generally comprise surfactants, an acid, builders such as sequestrants and chelating agents, coupling agents, and various other adjuvants.
A. The Surfactant System
Generally, the compositions of the invention comprise surfactants to facilitate low foaming cleaning, and prevent hazing of the PET container. Any number of surfactants may be used in accordance with the invention including nonionic surfactants, anionic surfactants, amphoteric surfactants, and mixtures thereof.
Nonionic surfactants encompass a wide variety of polymeric compounds which include specifically, but not exclusively, ethoxylated alkylphenols, ethoxylated aliphatic alcohols, ethoxylated amines, ethoxylated ether amines, carboxylic esters, carboxylic amides, and polyoxyalkylene oxide block copolymers.
Preferably, nonionic surfactants are used in the invention such as those which comprise ethylene oxide moieties, propylene oxide moieties, as well a mixtures thereof, and ethylene oxide-propylene oxide moieties in either heteric or block formation. Additionally useful in the invention are nonionic surfactants which comprise alkyl ethylene oxide compounds, alkyl ethylene oxide-propylene oxide compounds and alkyl ethylene oxide-butylene oxide compounds, as well as mixtures thereof. The ethylene oxide propylene oxide moiety and ethylene oxide-butylene oxide moiety may be in either heteric or block formation. Also useful in the invention are nonionic surfactants having any mixture of combination of ethylene oxide-propylene oxide moieties linked to an alkyl chain where the ethylene oxide and propylene oxide moieties may be in any randomized or ordered pattern and of any specific length. Nonionic surfactants useful in the invention may also comprise randomized sections of block and heteric ethylene oxide propylene oxide, or ethylene oxide-butylene oxide.
Preferred nonionic surfactants include alkylphenols, alcohol ethoxylates, and block copolymers of ethylene oxide and propylene oxide.
Examples of nonionic surfactants found useful in the invention include (EO)/(PO) block copolymers having at least about 3 moles (EO) and at least about 15 moles (PO); aryl or aliphatic ethoxylates having at least about 3 moles (EO) which may or may not be capped with methyl, butyl, or benzyl moieties; aryl or aliphatic ethoxylate-propoxylate copolymers having at least about 2 moles of (EO) and from about 4 moles of (PO) and which may also be capped with methyl, butyl or benzyl; and aryl or aliphatic ethoxylate-butoxylate copolymers having at least about 2 moles of (EO) and about 4 moles of (BO) and which may also be capped with methyl, butyl or benzyl. The aliphatic group may comprise any branched or linear C8-C24 moiety. The aryl group may generally comprise aromatic structures such as benzyl. An HLB value of 4 to 13 may also be used to characterize surfactants useful in the invention.
Representative nonionics which are useful in the invention include EO/PO block copolymers available from Henkel KGaA; Pluronic L62 and L44 which are EO/PO block copolymers available from BASF; Tergitol 15-S-3, TMN3, TMN10 which are ethoxylated alcohols available from Union Carbide; Surfonic L24-1.3 which is a linear alcohol ethoxylate available from Texaco Chemical Co.; nonyl phenol ethoxylates such as NPE 4.5, NPE 9, and Surfonic N120 available from Texaco Chemical Co.; ethoxylated alkyl amines such as ethoxylated coco amine available from Sherex Chemical Co. as Varonic K-215; an alkyl ethoxylated carboxylic acid such as Neodex 234; and benzylated alcohol ethoxylates and EO/PO block copolymers among other nonionic surfactants.
Also useful in the invention are low foaming surfactants which may oil out of the wash solution at a temperature of 59xc2x0 C. or less. Preferably, the surfactant system comprises surfactants having a cloud point of about 5xc2x0 C. to 60xc2x0 C., preferably from about 10xc2x0 C. to 50xc2x0 C., and more preferably of about 10 to 20xc2x0 C. so that in the alkaline wash solution, the surfactants will oil-out or film and deposit on the PET container surface providing protection against hazing.
One preferred line of surfactants includes Dehypon LT104 which is a C12-18 fatty alcohol (EO)10 butyl capped and LS24 which is a C12-14 fatty alcohol ((EO)2 (PO)4) both available from Henkel Canada Ltd.
Anionic surfactants may also be used in the invention. Typical commercially available anionic surfactants provide either a carboxylate, sulfonate, sulfate or phosphate group as the functional anion. We have found that carboxylate based anionic surfactants such as alcohol ethoxylate carboxylates reduce hazing of the container. A commercial source of this type of surfactant is Neodox 234-4(trademark) available from Shell Chemical Co.
Amphoteric surfactants may also be used in the invention. Such amphoteric surfactants include betaine surfactants, sulfobetaine surfactants, sarcosinate surfactants, amphoteric imidazolinium derivatives and others. Certain surfactants found useful in hazing reduction include cocoyl and lauroyl sarcosine/sarcosinates such as Hamposyl C and L available from Hampshire Chemical Co.
B. Acid
The composition of the invention may also comprise an acid source. The acid functions to stabilize the surfactant system so that prior to mixing in the wash solution, the concentrate is a true phase stable solution. Once added to the alkaline wash solution the acids are neutralized, become salts, and provide heightened cleaning efficacy and retard the formation of scaling on washing machine components. Generally, the acid may be any number of organic or inorganic acids.
Inorganic acids useful in the composition and the invention include phosphoric acid, polyphosphoric acid or acidic pyrophosphate salts, among others. Organic acids useful in the invention include mono and polycarboxylic acids such as acetic acid, hydroxyacetic acid, citric acid, gluconic acid, glucoheptanoic acid, lactic acid, succinic acid, malonic acid, glutaric acid, and mixtures thereof.
C. Builders
The composition of the invention may also comprise a builder. Builders, i.e., sequestrants and chelating agents, retard the precipitation of scale onto the side walls of the PET container and the bottle washing machine. Builders also facilitate soil suspension, bind hardness ions and, in turn, enhance cleaning, during the washing process. In accordance with one embodiment of the invention the first concentrate may contain a first builder and the second concentrate may contain a second builder.
Builders which may be used in accordance with the invention include sequestrants such as phosphonates, phosphinates, acrylates and polyacrylates, and polycarboxylates, among others. Also useful as builders are maleate polymers and copolymers of maleate and acrylate; salts such as polyaspartic and polyglutaric acid salts; erythorbic acid; polyacrylamidopropyl sulfonate; and phosphino carboxylic acid, among others.
Water soluble acrylic polymers which may be used include polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymers, hydrolyzed polyacrylamide, hydrolyzed methacrylamide, hydrolyzed acrylamide-methacrylamide copolymers, and mixtures thereof. Water soluble salts or partial salts of these polymers such as their respective alkaline metal (for example sodium or potassium) or ammonium salts can also be used.
Also useful as builders are phosphonic acids and phosphonic acid salts. Such useful phosphonic acids include, mono, di, tri, tetra and, penta phosphonic acids which can contain groups capable of forming anions under alkaline conditions.
The phosphonic acid may also comprise a lower molecular weight phosphonopolycarboxylic acid such as one having about 2-4 carboxylic moieties and about 1 to 5 phosphonic acid groups. Such acids include 1 phosphono-1-methylsuccinic acid, phosphonosuccinic acid and 2-phosphonobutane-1,2,4 tricarboxylic acid.
Preferred sequestrants include the Dequest(copyright) sequestrants available from Monsanto Co. including Dequest 2006(copyright) which is amino tri(methylene phosphonic acid) pentasodium salt; Dequest 2010(copyright) which is 1-hydroxyethylidene-1,1-diphosphonic acid; Bayhibit AM(copyright) available from Mobay Chemical Co. which is 2-phosphonobutane-1,2,4-tricarboxylic acid; Dequest 2000(copyright) which is aminotri(methylene phosphonic acid); and Belsperse 161(copyright) from Ciba Geigy which is a phosphino polycarboxylic acid.
The builder present in either concentrate may also be a chelating,agent. Unlike a sequestrant, the chelating agent tends to bind alkali earth metals present in the wash solution and hold these compounds in solution. It is believed that mold uses the organic portion of nutrients leaving behind inorganic salts. As a result, the ineffective removal of mold is often indicated by inorganic salts which are left behind on the surface of the PET container. The chelating agent removes these inorganic salts that are found underneath the mold.
The number of bonds capable of being formed by a chelating agent upon a single hardness ion is reflected by labeling the chelating agent as bidentate (2), tridentate (3), tetradendate (4), etc. Any number of chelating agents may be used in accordance with the invention. Representative chelating agents include salts of amino carboxylic acids, phosphonic acid salts, water soluble acrylic polymers, among others.
Suitable amino carboxylic acid chelating agents include N-hydroxyethyliminodiacetic acid, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), N-hydroxyethyl-ethylenediaminetriacetic acid (HEDTA), and diethylenetriaminepentaacetic acid (DTPA), as well as isoserine-N,N-diacetic acid, beta alanine N,N-diacetic acid, sodium glycolate, and tripolyphosphate, among others. In accordance with one useful aspect of the invention the second builder present in the second concentrate comprises an amino carboxylic acid chelating agent, preferably of ethylene diamine tetracetic acid or salts thereof.
D. Couplers
The composition of the invention may also include a coupling agent. The coupling agent functions to stabilize the concentrate composition so that it is a true phase stable solution.
To this end, any number of organic coupling agents may be used including sulfates, sulfonates, as well as monofunctional and polyfunctional alcohols. Preferred coupling agents include sulfonate and sulfate compounds such as sodium xylene sulfonate, sodium cumene sulfonate, sodium toluene sulfonate, 2-ethylhexyl sulfate, alkyl diphenyl oxide disulfonate where the alkyl group is either a branched C12 or a linear C10, sodium alkyl naphthalene sulfonate, and sodium octane sulfonate and disulfonate, and mixtures thereof.
Those coupling agents which have been found useful include linear alkyl alcohols such as, for example, ethanol, isopropanol, and the like. Also useful are polyfunctional hydroxy compounds such as alkylene glycols like hexylene glycol and propylene glycol; phosphate esters including Gafac RP710 from Rhone-Poulence Chemicals, and Triton H-66 from Rohm and Haas Co.
E. Adjuvants
The compositions and methods of the invention may use any number of other adjuvants such as added nonionic surfactant defoamers such as those disclosed in U.S. Pat. No. 5,516,451 to Schmitt et al. which is incorporated herein by reference. Tracing compounds such as potassium iodide, colorants and dyes, fragrances, and preservatives, among other constituents are also useful in the invention.
The method of the invention provides heightened cleaning efficacy of PET containers, removing soils, inorganic salts, and molds while retarding hazing of the containers. This result is obtained by formulating a first acidic concentrate with a high concentration of surfactant and a separate second concentrate having a high concentration of builder.
In accordance with one aspect of the invention the first and second concentrates may be incompatible if mixed separately from a wash solution. Incompatibility in this context stems from different pH requirements of the two different concentrates. The first concentrate may generally have an acidic pH of less than about 2 to maintain the solubility of the surfactant system. The pH of the second concentrate is selected to provide complete solubility of the builder and is generally alkaline. Combination of the two concentrates before dilution in the wash solution may result in phase separation of the surfactant system or the builder depending on pH.
In use the two concentrates are combined in an alkaline wash system to provide heightened cleaning efficacy with good building efficacy. Illustrative concentration ranges for each of the two concentrates are provided below:
In use this system is diluted into a wash solution comprising from about 0.1 wt-% to 0.8 wt-%, preferably from about 0.2 wt-% to 0.3 wt-% of the first concentrate and from about 0.2 to 1.2 wt-%, and preferably from about 0.4 wt-% to 0.8 wt-% of the second concentrate. The ratio of the first concentrate to the second concentrate in the alkaline wash solution generally ranges from about 0.1:0.5 to 0.1:1.0, and preferably from about 0.1:0.2 to 0.15:0.3. Generally the alkaline wash solution may have a total of from about 0.3 to 2.0 wt-% and preferably from about 0.5 to 1.2 wt-% of both concentrate 1 and concentrate 2.
In accordance with one preferred aspect of the invention, the wash solution comprises at least about 1000 ppm EDTA, at least about 5 ppm of a phosphonate compound, and at least about 100 ppm of a gluconate compound.
The washing of PET containers generally takes place over a number of steps. The PET containers are emptied and pre-rinsed, then soaked in the wash solution. The wash solution generally has anywhere from 1.0 wt-% to 5 wt-% and preferably from 1.5 wt-% to 3 wt-% caustic (NaOH). Into this system is mixed Concentrate 1 and Concentrate 2 into which the PET containers are applied. Washing tends to take place over a time period which ranges from about 7 to 20 minutes. The wash temperature is about 59xc2x0 C. xc2x11xc2x0 C. The containers then pass through a weak caustic stage where water is run into the tank to continue cleaning and begin rinsing by reducing the sodium hydroxide concentration. The caustic concentration may be maintained by a conductivity controller. The containers then pass through at least three rinse stages which sequentially rinse the containers with warm water and cold water. The final rinsing takes place with potable water after which time the containers are turned upright, inspected, and filled.

Cleaning method for polyethylene terephthalate containers


A thermosetting weatherable powder coating composition applyable to a temperature sensitive substrate by means of electrostatic spray or fluidized bed, and curable at low temperature to form a textured surface to hide irregularities on the surface of the underlying substrate. The powder coating composition includes a hardener with a functionality of 2 or greater capable of reacting with an acid or anhydride functional group, a polymeric coreactant with a functionality of 2 or greater capable of reacting with the hardener, a carboxylic acid functional polyester and optionally, a catalyst, but no texturing agent. The polymeric coreactant is made by polymerizing an ethylenically unsaturated monomer and at least one carboxyl acid functional ethylenically unsaturated monomer or anhydride functional ethylenically unsaturated monomer, and mixtures thereof.

1. Field of the Invention
The invention relates to new thermosetting powder coating materials. More particularly, the invention relates to new textured and weatherable powder coating compositions providing a textured surface to mask defects in the surface of an underlying substrate without using a texturing agent, and to the articles containing the same. The powder coating compositions are provided as powdered material, and are adaptable to electrostatic application to conventional substrates and substrates intolerant of high cure temperatures.
2. Description of the Related Art
The preparation and application of powder coating compositions is known in the surface coating art. Powder coatings are considered desirable because they contain little or no organic solvent. They consequently release minimal amounts of volatile organic compounds during storage, application, or cure of the materials. Accordingly concerns related to worker safety, as well as deleterious environmental effects, are minimized.
Historically powder coatings have been used primarily on metal substrates because of the tolerance of such substrates for relatively high cure temperatures and because of the ease with which metal objects may be grounded to provide a target of uniform electrical potential for electrostatic application. More recently, powder coatings have been applied to non-metallic substrates such as plastic and wood, more specifically, medium density fiberboard (MDF). Although some success has been achieved in coating such non-metallic substrates, problems remain. Wood and MDF release water and other compounds as gasses during the high temperature cure associated with traditional powder coatings. This outgassing disrupts the surface of the coating material during flow and cure, resulting in pinholes and other defects in the coating surface. Also, non-metallic substrates often present less uniform substrate surfaces for coating. A smooth coating applied over such a surface may display aesthetically undesirable variations.
One way to effect pleasing coverage of a non-uniform substrate is to provide a coating having a texture that masks the underlying non-uniformity of the substrate. Previously, textured coatings have been prepared by adding inorganic or rubber texturing material to existing powder coatings. However, such efforts have resulted in coatings of relatively poor weatherability.
Various powder coating compositions are described in the patent literature such as EP-A2-911 709 and the following United States patents. U.S. Pat. No. 4,341,819 describes a powder applied in a fusion coating process that yields a low gloss, wrinkled finish of heat reactive epoxy resulting from the use of methylene disalicyclic acid as the curing agent for the epoxy resin; U.S. Pat. No. 5,721,052 describes thermosetting powder coating compositions adapted to form a grainy textured finish on heat sensitive substrates, especially wood products such a particleboard, based on bisphenol A type epoxy resin and a texturing agent. U.S. Pat. No. 5,212,263 describes a powder coating composition forming a textured finish comprising epoxy resin, methylene disalicyclic acid and an imidazole Bisphenol A epoxy resin. U.S. Pat. No. 5,494,994 describes the production of a matt epoxy hybrid powder coating using salts of pyromellitic acid and various amines. U.S. Pat. No. 5,714,206 describes wood electrostatically coated with a thermosetting powder coating system in which a mixture of self-curing epoxy resin and catalyst is made to cure at low temperatures by the addition of a curing agent. The coatings disclosed, however, do not provide the advantageous combination of textures, low cure temperatures, and weatherability of the present invention without using a texturing agent.
The invention is directed to a textured and weatherable powder coating composition comprising a mixture of a hardener or curing agent with a functionality of 2 or greater capable of reacting with an acid or anhydride functional group, a polymeric coreactant with a functionality of 2 or greater capable of reacting with the hardener, a carboxylic acid functional polyester, and optionally, a catalyst. The polymeric coreactant is made by polymerizing ethylenically unsaturated monomers such as carboxylic acid functional ethylenically unsaturated monomers or anhydride functional ethylenically unsaturated monomers. The powder coating composition can provide a textured and weatherable finish without including a texturing agent.
The invention also includes a robust weatherable coating having a desired textured surface formed by applying the composition to at least one surface of a substrate and curing the same thereon. The invention provides the weatherable textured coating to cover the surface nonuniformities found, such as in wood, MDF and other substrates. Moreover, the invention also includes textured and weatherable coatings having a low-temperature cure characteristic that minimizes the volatilization of compounds within the substrate during cure and thus minimizes disruption of the coating surface.
The composition of the invention is readily applied using conventional means, including electrostatic spray and fluidized bed methods, to various substrates, such as metal and heat sensitive substrates, e.g., plastic and wood substrates, more specifically, medium density fiberboard (MDF). In some embodiments, the composition exhibits a reduced cure temperature, as compared to other embodiments of the invention or conventional textured coating compositions. Among other advantages, such reduced cure temperatures tend to diminish outgassing from some substrates. A reduction in outgassing is associated with reduced disruption of the coating surface during flow, and consequently improved ultimate coating quality.
In a further aspect, the composition and coating of the invention exhibits weatherability, including resistance to ultra-violet light, that is superior to other known textured coating compositions.
These favorable physical characteristics result from a composition comprising, a hardener with a functionality of at least 2 that is reactive with an acid or anhyride functional group, a polymeric coreactant that has a functionality of at least 2. The polymeric coreactant is reactive with the aforementioned hardener and includes a substantially ethylenically saturated polymer made by polymerizing ethylenically unsaturated monomers, in which at least one monomer is a carboxylic acid functional ethylenically unsaturated monomer, or an anhydride functional ethylenically unsaturated monomer. The composition does not include a texturing agent. In some embodiments, the composition may also include a catalyst. In addition, The composition may also include a variety of other components such as fillers, pigments, flow control agents and stabilizers, and the like, as would be clear to one of skilled in the art.
The hardeners useful in the invention include glycidyl functional compounds and betahydroxyalkylamides, which react with the carboxylic acid functional group. Examples of glycidyl functional hardeners for weatherable coatings include hydrogenated bisphenol A and bisphenol F epoxy resins, 1,3,5-tris(2,3-glycidyl- propyl) 1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, 1,3,5-tris(2,3-glycidyl-2methyl propyl) 1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, the diglycidyl ester of terephthalic acid and the triglycidyl ester of trimellitic acid. The 1,3,5-tris(2,3-glycidyl- propyl) 1,3,5-triazine-2,4,6-(1H,3H,5H)-trione is known by those skilled in the art as triglycidyl isocyanurate (TGIC), and is sold under the tradename of PT-810 from Ciba Specialty Chemicals Brewster, N.Y. The 1,3,5-tris(2,3-glycidyl-2methyl propyl) 1,3,5-triazine-2,4,6-(1H,3H,5H)-trione is sold under the tradename MT-239 and is available from Nissan Chemical. The mixture of the diglycidyl ester of terephthalic acid and the triglycidyl ester of trimellitic acid is sold under the tradename of PT-910 by Ciba Specialty Chemicals, Brewster, N.Y. Other glycidyl functional hardeners for weatherable coatings may also include glycidyl functional acrylic resins which may be produced by polymerizing glycidyl functional acrylates alone or in combination with other vinyl monomers, including other acrylic esters, styrene and substituted styrenes, etc. Glycidyl functional acrylate monomers may include glycidyl acrylate, glycidyl methacrylate, beta-methylglycidyl acrylate, beta-methylglycidyl methacrylate, N-glycidyl acrylic acid amide and the like, among which glycidyl acrylate and glycidyl methacrylate are preferred. Examples of commercially available glycidyl functional acrylic resins include Fineclad(trademark)TA-244-A by Reichold, Almatex(trademark) PD 7690 by Anderson Co. and GMA 300(trademark) by Estron Chemical Company.
An example of a commercially available betahydroxyalkylamides hardener is the Primid 552 available from EMS-Primid, Sumter, S.C.
The acid and/or anhydride functional polymeric coreactant include those that may have an acid number of from about 20 to about 500 and those that may be produced by polymerizing acid/anhydride monomers such as acrylic acid, methacrylic acid, maleic anhydride with at least one of the following monomers: alkyl esters of acrylic acid or methacrylic acid such as methyl acrylate, ethyl acrylate, normal butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, normal butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, laurol methacrylate, tridecyl methacrylate, stearyl methacrylate, and cyclohexyl methacrylate, styrene, vinyltoluene, alpha-methylstyrene and beta-methylstyrene, ethylene, propylene, any of the butenes and pentenes, hexene, heptene, octene, etc. Commercially available carboxylic acid and/or anhydride functional coreactants include SMA1440 made by Elf Atochem, Philadelphia, Pa. and the Joncryl SCX-835, SCX-842, SCX-843 and the SCX-848 which are made by S.C. Johnson, Racine, Wis.
The carboxylic acid functional polyesters of this invention include those formed by the condensation reaction of aliphatic polyols, including cycloaliphatic polyols, with aliphatic and/or aromatic carboxylic acids and anhydrides. Examples of suitable aliphatic polyols include 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane dimethanol, trimethylolpropane, and the like. Suitable carboxylic acids and anhydrides include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, trimellitic acid, and anhydrides thereof.
The polyol and the acid or anhydride are reacted together in any ratio provided that an excess of acid over alcohol is used so as to form a polyester which has free carboxylic groups. Preferably, the carboxylic acid polyester have an acid number of from about 20 to about 80, more preferably from about 25 to about 60, and are solid at room temperature. The polyester is further characterized as having a Tg of, preferably, from about 30xc2x0 C. to about 85xc2x0 C., and more preferably, from about 40xc2x0 C. to about 75xc2x0 C. If the Tg is below 30xc2x0 C., the polyester and the powder coating composition containing the same tend to be sticky and difficult to handle. If the Tg is above 85xc2x0 C., the melt flow of the polyester is low and the coating may have poor coverage of the substrate being coated.
The carboxylic acid polyesters may have an acid number of, preferably, from about 20 to about 80 and more preferably, from about 25 to about 60. The acid number is measured using the ASTM 4662-98.
Commercially available polyesters suitable for the present invention include the products under the tradename Uralac P5700 sold by DSM Chemical, Zwolle, Netherlands.
The textured thermosetting powder coating composition contains a ratio of the hardener to the sum of said polymeric coreactant and said polyester of between about 0.7 to about 1.5 times the stoichiometric ratio and prefereably between about 0.9 to about 1.3 times the stoichiometric ratio.
In a second aspect, the composition may also include a catalyst that allows the powder coating to cure at temperatures within the range from about 200xc2x0 F. to about 300xc2x0 F. The catalyst is selected from the group of acidic and basic compounds, including imidazoles, imidazolines, tertiary amines, organic acid salts of imidazoles, imidazolines and tertiary amines, imidazole adducts with epoxies, quaternary ammonium salts, phosphonium halides, phosphines, phosphites, metal alkoxides, Lewis acids, tin catalysts, and the like. Examples of organic acids which may be used to prepare salts of imidazoles, imidazolines and tertiary amines include acids such as dodecanedioic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, benzoic acid, succinic acid, maleic acid, acetic acid, and 2-ethylhexanoic acid. Examples of suitable compounds include imidazoles such as imidazole, 2-methylimidazole, 2-propylimidazole and 2-phenylimidazole, imdazolines such as 2-phenyl-2-imidazoline and 2-methyl-2-imidazoline, tertiary amines such as 1,4-diaza-[2.2.2]-bicyclooctane, piperidine, morphline, N-methylmorpholine, N-ethylmorpholine, and 4-N,N-dimethylaminopyridine, organic acid salts such as the monosalt and disalt of dodecanedioic acid with 2-phenyl-2-imidazoline, the monosalt and disalt of adipic acid with 2-phenyl-2-imidazoline, the monosalt and disalt of dodecanedioic acid with 2-methyl-2-imidazole, and the monosalt and disalt of adipic acid with 2-methyl-2-imidazole,imidazole adducts with epoxies such as Epicure P-101 (2-methylimidazole adduct with bisphenyl A epoxy resin from Shell Chemical), quaternary ammonium salts such as myrystyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, choline chloride, and tetramethylammonium bromide, phosphonium halides such as ethyltriphenylphosphonium bromide, ethyltriphenylphosphonium iodide, butyltriphenylphosphonium bromide and butyltriphenylphosphonium chloride, phosphines such as triphenylphospine, phosphites such as tri-n-octylphosphite, metal alkoxides such as sodium methoxide and potassium tertiary butoxide, Lewis acids such as boron trifluoride monoethylamine salt, tin catalysts such as stannous octoate, and mixtures thereof. Preferred are 2-methylimidazole, 2-phenyl-2-imidazoline and the monosalt and disalt of dodecanedioic acid with 2-phenyl-2-imidazoline. More preferred is the disalt of dodecanedioic acid with 2-phenyl-2-imidazoline.
Examples of commercially available catalysts include 2-phenyl-2-imidazoline under the tradename Vestagon B-31 made by CreaNova, Inc., Somerset, N.J.; 2-methyl imidazole under the tradename Actiron 2MI made by Synthron, Inc., Morganton, S.C.; myrystyl trimethyl ammonium bromide sold under the tradename Mytab by Zeeland Chemicals, Zeeland, Mich.; ethyltriphenylphosphonium bromide, ethyltriphenylphosphonium iodide, butyltriphenylphosphonium bromide, and butyltriphenylphosphonium chloride, all available from Morton Performance Chemicals, Danvers, Mass.
Pigments and extenders may be added to the powder coating compositions. Examples of pigments that may be added to give the powder coating compositions color include, but are not limited to, titanium dioxide, carbon black, organic and inorganic pigments of any available color, micas, aluminum flakes and the like. Extenders that may be added to the powder coating compositions include, but are not limited to, barium sulfate, calcium carbonate, and the like.
Flow control agents may be added as another component to the powder coatings compositions disclosed. The flow control agents that may be employed in the thermosetting powder coating compositions are exemplified by, without limitation, acrylic resins. These acrylic resins are generally liquids that have been converted to powder form by absorption onto silica-type materials. A preferred flow control agent is an acrylic resin sold under the tradename Resiflow P-67 by Estron Chemical, Inc., which is a 2-propenoic acid, ethyl ester polymer. Another preferred flow control agent is sold under the tradename Benzoin by DSM, Inc., which is a 2-hydroxy-1,2-diphenylethanone crystalline solid that is believed to keep the molten coating open for a suitable time to allow outgassing to occur prior to the formation of the hard set film. The flow control agent is used, preferably, in a range from about 0.2 to about 5 pphr, and more preferably, from about 0.5 to about 2.5 pphr (parts per hundred resin).
Fumed silica and aluminum oxide may also be employed as a powder dry flow additive. An example of fumed silica is sold under the tradename Cab-O-Sil by Cabot Corporation. An example of aluminum oxide is sold under the tradename Aluminum Oxide C by Degussa Corporation.
The composition of the invention is prepared by making a mixture of hardener, polymeric coreactant, polyester, and optionally, catalyst and other ingredients. In one embodiment, the ingredients are provided as chips, flakes, or powder, or mixtures thereof, and are mixed by tumbling in a closed container. The resulting mixture is then introduced into an extruder where it is melt-blended to form a molten extrudate of more or less uniform composition. The typical extruder for the manufacture of powder coatings exhibits a length to diameter ratio of 15:1, and residence time of the material in process within the extruder is within the range from about 10 seconds to about 3 minutes, and typically on the order of 30 seconds. In the examples discussed below, the first and second heat zones of the extruder where set for 100xc2x0 F. and 250xc2x0 F. respectively, and the screw speed was approximately 500 RPM.
Another embodiment of the invention includes introducing the unmixed ingredients directly into the extruder, where adequate mixing is achieved directly in the melt-blending step.
Alternatively, the unmixed ingredients may be introduced into a medium-intensity mixer or a high-intensity mixer whereby deagglomeration of powder particles and improved dispersion are achieved prior to introduction of the mixture into the extruder.
Typically, greater uniformity of dispersion of the premix components insures greater uniformity in the qualities of the powder coating which ultimately results.
On emergence from the extruder, the temperature of the extrudate is typically between 180xc2x0 F. and 300xc2x0 F. It is immediately cooled, thereby preventing unwanted reaction of the blended ingredients and premature cure of the thermoset material. Cooling is often achieved by extruding the molten material directly into the pinch of a pair of chilled rollers, typically operated between about 35xc2x0 F. and about 40xc2x0 F. Contact with the chilled rollers solidifies the extrudate, and forms it into a web approximately xe2x85x9xe2x80x3 thick. The material of the web is chipped in a chipper and the chipped material is subsequently ground to a fine powder in a grinder or air classification mill. The resulting powder is sieved through a mesh sieve, and a powder dry flow control agent such as fumed silica or aluminum oxide may be added to improve product stability during storage and shipment.
Although particles of a wide range of sizes are known by those of skill in the art to be useful, the powder of the invention is preferably prepared to have an average particle size of from about 20 microns to about 80 microns.
The powder coating compositions as illustrated in the examples are prepared by first blending all dry ingredients together, then melt mixing the ingredients at a temperature of between about 180 and about 280xc2x0 F. in a twin screw extruder, such as an APV extruder operating at a screw speed of 500 RPM. Residence time in the extruder may range from about 10 seconds to about 2 minutes, with typical residence times being from about 20 to about 40 seconds. Melt blending is performed under ambient atmosphere. These melt blended powder coating compositions are immediately cooled upon exiting the extruder and then they are broken into small chips. These small chips are then ground in an Alpine mill and passed through a suitable mesh screen depending on the application.
Without intending to be bound by a theory of operation, it is believed that, in general, a powder coating composition is melted after coating onto the surface of a substrate. During the melting process, the particles melt and coalesce into a smooth coating over the surface, eliminating any roughness by filling in the crevices and defects of the surface. Usually, the lower the viscosity of the composition, the more the leveling and the smoother the finished surface. When it is desirable to have a textured coating, the current approach is to use texturing agents in the powder coating compositions. Surprisingly, the compositions of the invention have low viscosity when heated to produce good coverage of exposed surfaces, possess low cure temperature, and make coatings that have varied textured finishes. Thus, for a wood or wood product surfaces, a textured surface is produced without the presence of any texturing agents. It is believed that the combination of the polymers and particularly, of the polymeric coreactant with the polyester, results in incompatibilities that cause stresses to be built up in the powder coating composition during cure. These stresses develop when the coatings are heated and the acid or anhydride groups available in the ethylenically saturated polymeric coreactant and the acid groups in the polyester react with the hardener. Under the process conditions described herewithin, these reactions are believed to cause the formation of discrete domains of ethylenically saturated polymeric coreactant and of polyester, each material being largely absent from the domains of the other. However, stresses existing due to compositional gradients at domain boundaries result in a variety of surface textures in the cured product. This is unexpected since many of these polymers are low in viscosity and it is expected that flow and leveling of these powder coating compositions would occur on heating.
The invention further functions by incorporating ultraviolet stable hardeners and curing agents in order to decrease degradation of the powder coatings when exposed to ultraviolet radiation. In particular the ethylenically unsaturated monomers are fully polymerized to minimize or eliminate sites of ethylenical unsaturation in the polymer backbone where ultraviolet radiation can cause chemical bond breaking reactions. More particularly, polyesters of the invention, which contain no sites of ethylenical unsaturation in the backbone of the polyester, also enhance the ultraviolet stability of the powder coatings of the invention. By utilizing mixtures of the polymeric coreactant made from ethylenically unsaturated monomers and carboxylic acid functional polyesters, surprisingly, textured powder coatings are created.
The texture of the coating can be classified as orange peel, mottled and fine textures.
In addition, the compositions of the invention also provide coatings having good weatherability. Weatherability is tested by measuring the changes in both gloss loss, reported as percent change, and color, reported as dE after aging for an extended periods of time under the following conditions: 63xc2x0 C. as measured on a black panel and 30% relative humidity using borosilicate filters. For good weatherability, it is preferred that the change in gloss and the change in color after 670 hours is about 30% better, more preferably, about 40% better, and most preferably, about 50% better compared to bisphenol A powder coating compositions, provided that the bisphenol A powder coating compositions and the composition of the invention should have comparable initial gloss and be formulated with conventional pigments.
Having reviewed the nature and preparation of the compositions and coatings of the invention, there follows herewithin, descriptions of various exemplary embodiments thereof. It should be noted that these examples are intended merely as illustrative examples of the invention described above and claimed below, and should in no way be construed to limit the scope of the claims.

H. B. Fuller Licensing and Financing, Inc.


Meta-xylene is recovered from admixture with other C8 aromatic hydrocarbons including ortho-xylene by liquid phase adsorptive separation. Performance is improved by reducing the concentration of ortho-xylene through adding a sidecut to a prefractionator preparing the feedstock to adsorptive separation.

The xylene isomers are important intermediates which find wide and varied application in chemical syntheses. Para-xylene is a feedstock for terephthalic acid which is used in the manufacture of synthetic textile fibers and resins. Meta-xylene is used in the manufacture of plasticizers, azo dyes, wood preservers, etc. Ortho-xylene is feedstock for phthalic anhydride production.
A typical C8-aromatics stream containing all of the xylene isomers and ethylbenzene is not readily separated into individual components due to their close boiling points. Ortho-xylene often is separated by fractional distillation, but requires a tower usually having 100-150 trays with high reflux ratios. Ethylbenzene can be separated by superfractionation with even more difficulty, but this generally is impractical. Para-xylene/meta-xylene separation by distillation is commercially impossible. Para-xylene has been separated by crystallization for some time, and adsorptive separation as disclosed in U.S. Pat. No. 2,985,589 has advanced to dominate commercial production.
Meta-xylene adsorptive separation, as disclosed in U.S. Pat. No. 3,773,846, U.S. Pat. No. 4,306,107, U.S. Pat. No. 4,326,092 and U.S. Pat. No. 5,900,523, also has been applied commercially. One issue in commercialization is that the presence of a significant concentration of ortho-xylene in the feed to meta-xylene adsorptive separation significantly increases equipment sizes and utility costs. This is not a problem if ortho-xylene is recovered by fractionation, but is important if the usual concentration of ortho-xylene is present in the feedstock to meta-xylene recovery.

Process for improved meta-xylene yield from C


A template 10 can be used to mark or scribe either a single gang opening or a dual gang opening for mounting an electrical box in a wall. The template is especially adapted to mark openings for xe2x80x9cold workxe2x80x9d boxes mounted directly to drywall. The template 10 includes a vertical level 16 and a horizontal level 18 protruding from the front face of the template 10 so that the template can be squared in either a horizontal or a vertical orientation. The level are mounted in housings 20, 30 that protrude far enough to form finger grips. The openings are cut around the periphery of the template and vertical slots 38, 44 are provided intermediate the sides of the template to form an opening for a single gang box. A dual gang box opening can be marked primarily using the peripheral edges of the template 10. Rectangular protruding sections 28, 36 and 40 provide clearance for tabs located on xe2x80x9cold workxe2x80x9d boxes and one of these protrusions 28 includes a slot for defining a portion of a dual gang box opening.

1. Field of the Invention
This invention is related to a template that is used to mark openings in a wall or partition for electrical boxes. More specifically, this invention is intended for use in marking openings for xe2x80x9cold workxe2x80x9d boxes of the type that can be attached directly to a partition or drywall. This invention is also directed to templates for markingssingle and dual gang boxes for applications in which additional branch wiring components are to be added and for the installation of local area network components in an existing structure.
2. Description of the Prior Art
When used with reference to the installation of electrical systems and wiring in buildings, the term xe2x80x9cold workxe2x80x9d refers to the installation of additional components to existing wiring or electrical systems or to the installation of additional wiring and components in an existing structure. The most common example is the installation of a new electrical outlet along a preexisting electrical branch. Since the existing wiring is normally located behind a wall or partition, such as drywall, an opening must first be cut in the desired location. Normally this location is chosen to provide access to the wires behind the drywall or other partition. To comply with applicable codes, an electrical box must then be. inserted into the opening. Since it is most unlikely that the newly formed opening will be in a position in which the newly installed box can be attached to a stud or other structural member, some means must be provided to attach the electrical box directly to the drywall or other partition.
A number of so-called xe2x80x9cold workxe2x80x9d electrical boxes include a screw mounted tab that can be rotated into position behind the drywall after the xe2x80x9cold workxe2x80x9d box has been inserted into the new opening. These tabs are normally mounted on a screw that is accessible from the front of the box. When the xe2x80x9cold workxe2x80x9d box is initially inserted through the wall opening, the tab is located in a retracted position in which the tab lies along an external face of the box. Normally tabs are located on the top and bottom of the xe2x80x9cold workxe2x80x9d box. After the box has been inserted, the screws to which the tabs are attached are rotated. The tabs are rotatable through an arc of ninety degrees. The face of the box provides a stop in the retracted position and a ridge extending at right angles to the box wall provides a second stop against which the tab abuts when rotated to the extended position. When in the extended position, the tab engages the area around the edge of the opening in the drywall.
Most of the xe2x80x9cold workxe2x80x9d boxes of this type are plastic or nonmetallic. In the most commonly used nonmetallic xe2x80x9cold workxe2x80x9d box, the tabs protrude from the top and bottom faces of the box even in the retracted orientation. Therefore, the opening in the drywall must provide clearance for the tabs, but it must not be so large that the tabs will not engage the dry wall along a length sufficient to adequately secure the xe2x80x9cold workxe2x80x9d box. Other commercially available boxes of this type include a step in the top and bottom wall so that a rectangular opening will provide clearance for the tab. This configuration, however, reduces the interior volume of the box. Examples of old work nonmetallic boxes include CARLON plastic boxes manufactured by Lamson and Sessions, old work plastic boxes manufactured by SLATER, and boxes manufactured by Allied Moulded of Bryan Ohio. Old work style boxes are also described in U.S. Pat. No. 3,966,152; U.S. Pat. No. 4,304,957; and U.S. Pat. No. 5,434,359.
In addition to these standard nonmetallic xe2x80x9cold workxe2x80x9d boxes, there are some metallic xe2x80x9cold workxe2x80x9d boxes. These metallic versions generally include tabs located on the sides of the box that are outwardly deflected by screws or spring tabs that extend beyond the sides of the boxes.
xe2x80x9cOld workxe2x80x9d boxes are not confined to standard single gang boxes that have an internal volume of approximately fourteen to eighteen cubic inches. In some applications, dual gang boxes, suitable for mounting two electrical devices are employed. xe2x80x9cOld workxe2x80x9d dual gang boxes have an internal volume of approximately twenty-five to twenty-eight cubic inches and have rotatable tabs at diagonally opposite corners of the top and bottom faces.
Although xe2x80x9cold workxe2x80x9d boxes are commonly employed to add electrical devices to conventional wiring branch circuits used rated at 12 VAC, they can also be used for installing low voltage or class 2 wiring components. Applications of this latter type have become increasingly prevalent due to the installation of local area network computer systems. In these applications, xe2x80x9cold workxe2x80x9d boxes are located as needed for network outlets and the low voltage cables are fished behind the pre-exiting wall partitions, commonly drywall. Installations of this type are needed not only to upgrade existing office complexes, but are also required in many manufacturing applications. However, aesthetic considerations dictate, especially in offices, that the outlets using these xe2x80x9cold workxe2x80x9d boxes be neat. If the boxes are not installed so that they are level, faceplates that are subsequently screwed to the boxes will not be level. If the openings through which the xe2x80x9cold workxe2x80x9d boxes are to be inserted are excessively large, undesirable cracks may be visible around the edges of the faceplates or it may be necessary to fill in these cracks as part of a labor intensive, and therefore expensive operation. Therefore it is important that some means be provided for cutting openings that are level and that are as small as possible so that the xe2x80x9cold workxe2x80x9d boxes can be securely mounted and so that no cracks are visible after installation of a faceplate to the box.
Commonly paper templates are supplied with xe2x80x9cold workxe2x80x9d boxes to permit an installer to mark the shape of the opening into which the box will be inserted. However, these paper templates provide no means for squaring the opening so that the sides with be vertical and the top and bottom horizontal. In other words other tools are necessary to level the template, an many installers merely eyeball the orientation of the template and the resultant opening. Another means of cutting openings in drywall is to employ a template that allows an installer to either trace the location of the opening or to cut the opening using a drywall cutter or zip tool. Examples of these prior art templates are shown in U.S. Pat. No. 4,793,069 and in U.S. Pat. No. 5,222,303. The later patent includes both horizontal and vertical levels to orient an opening the size of a single gang box in a vertical orientation. That device also employs an extension for locating the box at an outlet box height relative to a floor. However, that template is bulky and is not suited to orienting boxes in vertical or horizontal orientations, and being primarily intended for use with conventional duplex outlets, is not suited for mounting boxes in tight locations. Furthermore that device only provides a template for a single gang box. U.S. Pat. No. 4,793,069 does provide templates for both single gang and dual gang boxes, but because the box opening is defined by the edges of two separate internal openings in a flat plate, that template is also rather bulky and is not suitable for all uses of xe2x80x9cold workxe2x80x9d boxes.
Therefore a template that is suitable for marking either single or dual gang boxes in various locations, both for installation of additional components on existing. wiring, and for installing new wiring systems, such as local area networks, is needed. This template should be especially suited for use in installing xe2x80x9cold workxe2x80x9d single or dual gang boxes. The template should also be easily gripped and manipulatable, and it should be easy for an installer to position the template and various orientations and positions while still maintaining the template level or perpendicular to a plumb or horizontal line. The template should also be inexpensive to manufacture and should use conventional off the shelf bubble type levels to permit an installer to properly orient the template.
These objectives can be realized by employing a template for use in cutting an opening in an existing wall for installation of an old work electrical box. The template comprises a plate having edges defining the shape of an opening through which an old work electrical box can be inserted. The plate includes spaced apart gripping protrusions extending beyond a front surface and a level positioned between spaced gripping surfaces so that the template can be oriented relative to a plumb line.
This template for use in outlining an opening in a panel for installation of an old work electrical box in a panel comprises a plate having a width equal to the width of a dual gang old work electrical box opening with sections along a top and a bottom edge protruding from adjacent edge sections to define areas for clearance of an old work dual gang electrical box latch for insertion therein. The plate includes an additional section along one of the top and bottom edges with a horizontal slot extending through the additional section for defining a portion of the opening adjacent to the protruding section along the one top or bottom edge. The plate also includes at least one vertical slot so that the vertical slot is spaced from one side of the plate by a distance equal to the width of a single gang old work electrical box, the additional section along the top or bottom edge of the template defining an opening for clearance of an old work single gang electrical latch.
This template compriseia tool for use in cutting a hole in a wall for the installation of an electrical box. Templates for xe2x80x9cold workxe2x80x9d and new boxes would employ many of the same features with the periphery of the template being defined by the specific application. The tool comprises a flat member having peripheral edges, the peripheral edges being dimensioned to define a dual gang box opening,. A portion of the peripheral edges also are dimensioned to define a portion of a single gang box The flat member has at least one slot, the slot defining a remaining portion of the single gang box opening.

Template for scribbing electrical box openings for old work