A durable press process for rayon fiber-containing fabrics comprising treating a rayon fiber-containing fabric with an aqueous mixture containing a high concentration of formaldehyde, and a catalyst capable of catalyzing the crosslinking reaction between formaldehyde and the rayon, wherein the concentration of the formaldehyde is sufficient to produce a durable press fabric without substantially shrinkage of the treated fabric, followed by heat curing the treated fabric to produce a durable press rayon fabric without substantial shrinkage.

1. Field of Invention
This invention relates to a durable press/wrinkle-free process for cellulosic fiber-containing fabrics and more particularly to a process which permits high treatment level amounts of formaldehyde and catalysts to impart wrinkle resistance to the cellulosic fiber-containing fabrics while reducing the loss in both tensile and tear strength normally associated with such treatment processes. The process of the present invention is particular adopted for the treatment of rayon and rayon blend fabrics.
2. Description of Related Art
There are a number of known processes for treating cellulosic fiber-containing fabrics, such as cotton-containing fabrics, to make them wrinkle-free. These treatment processes include resin or polymer treatment of the fabric, but these are costly and unsatisfactory. Another process for treating cellulosic fiber-containing products relies on formaldehyde to provide durable cross linking of the cellulose molecules and to thereby impart durable crease resistant and smooth drying characteristics to these products. However, problems have been encountered with the known processes, especially when applied to rayon. A simple, reproducible, completely satisfactory low-cost formaldehyde durable press process for rayon has not yet been achieved.
It has long been known to treat cellulosic materials with formaldehyde, as is evidenced by U.S. Pat. No. 2,243,765. This patent describes a process for treating cellulose with an aqueous solution of up to 40% formaldehyde and a small proportion of an acid catalyst under such conditions of time and temperature that the reaction is allowed to approach its equilibrium.
It is further stated that, in carrying out this process, the proportion of the solution of formaldehyde to the cellulose must be at least such that the cellulose is always in a fully swollen state. It is also stated that the time and temperature of the treatment with the solution of formaldehyde and acid catalyst will vary with one another, the time required increasing rapidly as the temperature diminishes. When it is desired, the product may be isolated by washing and drying; preferably at a temperature of about 212xc2x0 F. The products obtained according to this process are said to show no increase in wet strength and possess a highwater imbibition, no increased resistance to creasing and a slight increase in affinity to some direct dyes. There is no mention of rayon in this patent although it does mention that the cellulose material may be bleached wood pulp.
In recent years additional methods have been devised for treating cellulosic fiber-containing products in order to impart durable crease retention, wrinkle resistance and smooth drying characteristics to these products. As discussed, formaldehyde has been cross linked with cellulose materials to produce these products. It is also known to treat cellulose materials with resins or precondensates of the urea-formaldehyde or substituted urea-formaldehyde type to produce a resin treated durable press product.
Textile fabrics treated with durable press resins require treatment with softening agents to achieve commercially acceptable hand, strength, and wrinkle recovery. U.S. Pat. No. 4,184,004 describes the treatment of a durable press resin treated fabric with a softener which is a silicone compound which may be a hydrophilic organosilicone terpolymer which contains a plurality of reactive epoxy groups. U.S. Pat. No. 4,520,176 also describes the use of silicone softeners for the treatment of aminoplast resin treated fabrics. The silicone softeners are organopolysiloxanes which are capable of being cross-linked.
As noted in U.S. Pat. No. 3,841,832, while formaldehyde has made a significant contribution to the cotton finishing art, it has had virtually no impact with respect to rayon containing fabrics even though rayon and cotton may be considered cellulosic containing fibers. Even with respect to cotton, the result has been far from perfect. For instance, in some cases the formaldehyde crosslinking treatment has tended to lack reproducibility, since control of the formaldehyde cross-linking reaction has been difficult.
U.S. Pat. No. 4,396,390, points out that the lack of reproducibility is especially true on a commercial scale. Moreover, unacceptable loss of fabric strength has also been observed in many of the proposed aqueous formaldehyde treatment processes. When high curing temperatures were used with an acid or potential acid catalyst, excess reaction and degradation of the cotton often happened which considerably impaired its strength. On the other hand, when attempts were made to achieve reproducibility at temperatures of 106xc2x0 F. or less, much longer reaction or finishing times were usually required, rendering the process economically relatively unattractive. A solution to this is set forth in U.S. Pat. No. 4,108,598, the entire disclosure of which is herein incorporated by reference. This patent specifically states that rayons, e.g. regenerated cellulose (both viscose and cuprammonium) may be treated by the process described therein but there is no exemplification of the treatment of rayon.
Rayon is chemically the same as cotton and for this reason one would expect that systems which are effective in treating cotton would also be effective in treating rayon. Rayon is made from wood pulp (cellulose) in which the original cellulose fibers are changed into a thick, syrupy solution that is pressed through a group of exceedingly fine openings called spinnerets to form long filaments. As these filaments emerge and solidify in an acidic liquid, they are put under tension and formed into strands. The strands are processed into yarns then woven into fabrics. However, rayon is a very amorphous fiber (its molecules are spread out) and rayon does not resemble cotton in the way it reacts, even though it is chemically the same as cotton. In fact, even though some of the prior art includes rayon as a possible cellulosic material to be treated with formaldehyde and acid catalysts, there is no commercially viable formaldehyde rayon treatment process and rayon is treated with resins to improve its properties. None of the above discussed patents contain examples which describe the treatment of rayon containing fabrics even though some of the patents refer to rayon containing fabrics as the type of fabric which may be treated by the process described in the patent.
Shrinkage is a very serious problem when aqueous systems are applied to rayon containing fabrics and because of this shrinkage, rayon containing fabrics generally require dry cleaning as opposed to washing in an aqueous solution, such as water and a detergent. This is a disadvantage for rayon fabrics and it would be a significant advance if rayon containing fabrics could be treated so as to make them washable in water and avoid the inconvenience and added expense of dry cleaning. When the fabric is made from 100% rayon fiber and subjected to aqueous washing, shrinkage may be as high as 18%-20%. The shrinkage problem is also severe with a polyester/rayon fabric, because the rayon shrinks so much, and the polyester shrinks so little, that the fabric becomes completely distorted due to the extreme difference in the rate of shrinkage of the two fibers which make the blended fabric. The fabric will not lay flat on aqueous washing, and manufactures are forced to require dry cleaning of a garment made from this type of fabric.
In accordance with the present invention it is possible to obtain good durable press properties in a rayon fiber-containing fabric with good strength retention with a process that produces consistent results and which controls shrinkage so that the resulting fabric may be cleaned using normal washing detergents and water and does not require that the fabric be dry cleaned. This invention relates to an aqueous durable press/wrinkle-free process for rayon fiber-containing fabrics and more particularly to a process which utilizes acid catalysts and high concentrations of formaldehyde. The formaldehyde concentration used in the process of the present invention is much higher than in the prior art durable press processes for the treatment of cotton containing fabrics. The invention includes the use of very active or hot catalysts in certain preferred aspects.
The invention also includes the fabrics treated by the process of the present invention. These rayon containing fabrics have unique properties including low shrinkage which makes them water washable and which provides a distinct commercial advantage to the rayon containing treated fabrics of the present invention.
In a further aspect of the invention, elastomers are used in the treatment process and especially silicone elastomers to reduce loss in both tensile and tear strength when subjecting the fabric to the durable press process of the present invention.
In another aspect of the invention, the fabric is moistened with water or an aqueous solution containing a wetting agent and the amount of moisture is controlled prior to the addition of the formaldehyde and acid catalysts. Strength enhancing additives such as urea and derivatives thereof may be added with the formaldehyde and acid catalysts in a still further aspect of the invention.
A problem associated with rayon fabrics and which has been overcome by the process of this invention is a reduction in the shine which develops when rayon fabrics are pressed with a hot iron. Rayon fabrics treated in accordance with the process of the present invention eliminate the xe2x80x9cshinexe2x80x9d which is developed on pressing a rayon fabric which has not been treated with the process. This is a further advantage of the process of the present invention.
The durable press process of the present invention for treating rayon containing fabrics, including 100% rayon fabric, comprises treating the rayon containing fabric with aqueous formaldehyde and a catalyst capable of catalyzing the crosslinking reaction between formaldehyde and cellulose, i.e., rayon. The concentration of the formaldehyde used in the process is much higher than the amount used in the prior art durable press processes for cotton, cellulose, containing fabrics. The effective treatment of rayon at such high formaldehyde and acid catalysts concentrations is totally unexpected because one skilled in the durable press art of cotton finishing with formaldehyde would have thought that the fabric would be completely destroyed at such high treatment levels, or at least rendered so weak that it would be commercially unacceptable. Obviously, the consumer will find a fabric with insufficient wear characteristics, such as durable press and strength, to be unacceptable. There are industry standards that fabrics must meet to be commercially acceptable. The treatment of rayon by the process of the present invention results in a novel treated rayon fabric which meets these standards and allows the treated fabric to be cleaned by conventional washing or laundering due to its stability to aqueous washing or laundering. Shrinkage of less than 2.5% may be achieved by the process of the present invention.
After the rayon containing fabric has been treated with the aqueous composition containing formaldehyde and acid catalysts, it is subjected to curing conditions. The rayon fiber-containing fabric, preferably having a moisture content of more than 20% by weight, is treated or cured under conditions at which formaldehyde reacts with the rayon in the presence of the catalyst, and without the substantial loss of formaldehyde before the reaction of formaldehyde with the rayon, to improve the wrinkle resistance of the fabric while reducing the loss in both tensile and tear strength. It is preferable that the rayon containing fabric is in the fully swollen state.
It is also preferable that an elastomer is present when the reaction with formaldehyde takes place and the elastomer may be applied to the fabric with the aqueous formaldehyde and catalyst solution. While any elastomer may be used, such as an acrylic elastomer, or a urethane elastomer; silicone elastomers are particularly preferred. Any silicone elastomer may be used in the present invention. Silicone elastomers are known materials. Silicone elastomers have a backbone made of silicon and oxygen with organic substituents attached to silicon atoms comprising n repeating units of the general formula:
The groups R and R1 may be the same or different and includes for example, lower alkyl, such as methyl, ethyl, propyl, phenyl or any of these groups substituted by hydroxy groups, fluoride atoms or amino groups; in other words, reactive groups to cellulose, i.e., rayon.
The silicones used to make the silicone elastomers in the present invention are made by conventional processes which may include the condensation of hydroxy organosilicon compounds formed by hydrolysis of organosilicon halides. The required halide can be prepared by a direct reaction between a silicon halide and a Grignard reagent. Alternate methods may be based on the reaction of a silane with unsatutrated compounds such as ethylene or acetylene. After separation of the reaction products by distillation, organosilicon halides may be polymerized by carefully controlled hydrolysis to provide the silicone polymers useful in the present invention.
For example, elastomers may be made by polymerization of the purified tertramer using alkaline catalysts at 212-302 degrees F., the molecular weight being controlled by using a monofunctional silane. Curing characteristics and properties may be varied over a wide range by replacing some methyl groups by xe2x80x94H, xe2x80x94OH, fluoroalkly, alkoxy or vinyl groups and by compounding with fillers as would be appreciated by one of ordinary skill in the art.
Silicone elastomers used in the present invention are high weight materials, generally composed of dimethyl silicone units (monomers) linked together in a linear chain. These materials usually contain a peroxide type catalyst which causes a linking between adjacent methyl groups in the form of methylene bridges. The presence of crosslinking greatly improves the durability of the silicone elastomer on rayon by producing larger molecules.
It is also possible to produce a reactive silicone elastomer, which is one where reactive groups capable of reacting with the substrate have been added to the linear dimethyl silicone polymer. These silicones are capable of reacting both with cellulose substrates as well as with most protein fibers, and are characterized by much greater durability of the silicone polymer on the substrate, even approaching the life of the substrate.
Another group of reactive silicone polymers are the hydrophilic organosilicone terpolymers which are elastomers and which contain a plurality of reactive epoxy groups and a plurality of polyoxyalkylene groups as described in U.S. Pat. No. 4,184,004, the entire disclosure of which is herein incorporated by reference. Other silicone elastomers which may be used in the process of the present invention include the ester containing silylated polyethers described in U.S. Pat. No. 4,331,797, the entires disclosure of which is herein incorporated by reference. Also incorporated by reference is the disclosure of U.S. Pat. No. 4,312,993 which describes silylated polyethers which may be used in the process of the present invention.
Silicone elastomers which give off reaction gases or chemicals indicating chemical reaction with the substrate are much preferred over non-reactive silicone elastomer, but this is not to say that non-reactive silicone elastomers cannot be used in the process. Different elastomers, purchased from different manufacturers have all shown increases in tensile as well as tear strength, as shown in the tables included herein. Elastomeric silicone polymers have been found to increase strength whereas simple emulsified silicone oils (or lubricants) do not give increases in tensile strength.
The aqueous system containing formaldehyde, an acid catalyst, silicone elastomer and a wetting agent may be padded on the fabric to be treated, preferably to insure a moisture content of more than 20% by weight on the fabric, and then the fabric cured. The silicone elastomer composition is contained in the aqueous system in an amount to provide from 0.1 to 5%, (0.053-2.65% solids OWF) preferably 1 to 2% (0.53-1.06% solids OWF) and most preferably, about 1.5%, (0.795% solids OWF), of the composition on the weight of the fabric.
The padding technique is conventional to the art and generally comprises running the fabric through the aqueous solution which is then passed through squeezing rollers to provide a wet pick-up of from about 50 to about 100% or more. As is conventional in the art, the concentration of the reactants in the aqueous solution are adjusted to provide the desired amount of reactants on the weight of the fabric (OWF).
In a preferred aspect of the invention, the fabric is pre-moistened before it is run through the chemical treatment bath containing the formaldehyde and catalysts. The premoistening is with water or an aqueous solution containing a wetting agent. Conventional wetting agents well known to one of ordinary skill in the art of durable press treating cotton with formaldehyde may be employed in the solution, generally in amounts of 0.1% (0.1% solids OWF) based on the weight of the solution. This results in an insignificant amount of wetting agent applied to the fabric, based on the weight of the fabric. This wetting agent insures that the treating solution will find its way into the fibers so that the entire fiber is treated with the treatment solution, and not just the outside of the fiber. (This would lead to a very poor treatment). Any non-ionic wetting agent can be used, ionic agents can cause break down of the treating solution, especially the elastomer, hence, the wetting agent should be carefully chosen, and tested in the laboratory as would be appreciated by one of ordinary skill in the art. This is a routine procedure, i.e., it requires no more than routine experimentation by one skilled in the art.
The pretreatment with the aqueous solution may be obtained by running the fabric through an aqueous bath and then through rollers to remove excess moisture or by the use of conventional low wet pick-up equipment, i.e., vacuum equipment etc., and to control the amount of moisture in the fabric prior to the application of the treatment chemicals in a separate bath. It is essential to know the moisture content of the fabric reaching the treatment bath so that the concentrations of the chemicals applied in the treatment bath can be determined and adjusted to insure that the correct amounts of reactants are on the fabric prior to curing to obtain the desired levels of treatment. The amount of moisture on the fabric prior to the application of the treatment chemical will dilute the amount of chemicals which the fabric xe2x80x9cseesxe2x80x9d after the pre-moistened fabric is run through the treatment bath.
The above procedure, which is called a wet on wet application of the aqueous chemicals, produced 13% higher strength than when the chemicals were applied to dry fabric. Shrinkage was considerably better when dealing with wet fabric, rather than dry.
Regardless of the reaction mechanism, one thing is known for sure, complete wetting and saturation is obtained when the fabric has been pre-wet, whereas on dry fabric, there is no guarantee that the fabric and all fibers are thoroughly saturated and swollen to the same degree. In fact, applicant found the dry fabric difficult to wet out evenly as it was padded with aqueous chemical treatment solutions. In the wet on wet application, water and wetting agent were applied first, giving time for complete saturation before the aqueous chemicals were applied.
While not wishing to be bound by any theory, if one were to visualize a fabric where there are spots of heavily wetted areas, next to areas that are not wet out. The heavily wet out areas contain more chemical than they should, as the application should have spread to the area where there is nothing, or less solution. Treatment where the chemical concentration is higher will be more severe than in an adjacent area where less chemicals are found. It is the poor wet out, or poor uniformity that leads to weak, or over treated micro areas as well as strong untreated areas in the fabric. The strength of the fabric is only as good as the weakest spot.
Now visualize a fabric that has been wet out to 50% with water before chemicals are applied, and are suddenly dipped in a two times concentration of chemicals, (two times stronger to account for the water already in the fabric). Now as the chemical solution is diluted two to one with the water in the fabric, not only is a normal concentration achieved, but the chemicals can move everywhere in and on the fibers. There are no concentrated areas, everything is equally treated, hence the chemical reaction will give a fabric without micro-weak spots. It is believed that this is how wet on wet treatments give higher strength.
It is noted that when treating dry fabric, that is fabric with an ambient amount of moisture, half the amount of formaldehyde was used, for reasons outlined above. (The pre-wet out fabric already contains water.) What is not clear is that in applying the aqueous mixture to dry fabric that one half of the catalyst concentration was not used. The reason for this is not so obvious. Catalyst concentration runs it""s own curve and does not necessarily follow the formaldehyde curve precisely. It levels off sooner, hence if one half of the catalyst concentration used in wet on wet treatments had been used in the wet on dry treatments, there would not have been enough catalyst present to give a good reaction or good treatment. The concentration used is based on all the previous work which applicant has done on application of the aqueous mixture to a dry fabric. By consulting previous data, the appropriate catalyst concentration was chosen, and as the data shows, strengths, though a bit less than wet on wet treatments, are quite close. What is surprising is that shrinkage control in the dry fabric treatments is not as good. If the catalyst concentration had been cut in half, shrinkage would have been even worse.
As noted, the addition of urea to the treating solution results in a 30% increase in strength. Urea may be added to the aqueous treating composition to provide from 0.5 to 3% of urea on the weight of the fabric, preferably from 1-2% OWF. The mechanism of this strength increase is not known as yet, but it is totally reproducible on woven fabrics, and knits. The urea is first dissolved in water before adding to the treatment bath, and is added just before any wetting agent is added to the treatment bath. As noted above, a wetting agent may also be added in the premoistening step. Surprisingly, the use of urea left the fabric stronger by at least 30% in both tensile as well as tear strength. This effect of urea appears to be peculiar to the aqueous system of the present invention, as it does not give the increase in strength with other formaldehyde crosslinking processes. However, there is a very slight lessening of the DP value. It is a simple matter to increase the treatment, to account for the half point drop in DP and still realize the 30% strength increase.
While it is preferred to use urea, urea derivatives which are compatible with the aqueous system may also be used in comparable amounts which may be readily determine by one skill in the art based on the amount of urea added to the system. These derivatives include substituted ureas where one or more organic groups are substituted for one or more of the urea hydrogen atoms. Such organic groups include lower alkyl, i.e., methyl, ethyl, propyl, provided that the urea derivatives"" water solubility in the aqueous system is not adversely effected. Similarly, thiourea and its water soluble derivatives may also be used.
The treatment level is largely dictated by the amount of formaldehyde used in the treating solution, but also by the amount of catalyst employed. Catalyst should be used in a ratio with the formaldehyde, e.g., more formaldehyde, more catalyst, etc. The other components, softener, urea and wetting agent have no effect on the level of treatment.
The level of treatment selected is dictated by the fabric, some fabrics can withstand high level of treatment, others cannot. The following are rules of thumb, but experimental trials should show what treatments can be used.
It is possible to use unexpected high temperatures which allow the crosslinking reaction to take place before the loss of formaldehyde is great enough to affect the process and provide inadequate treatment. In accordance with this aspect of the invention, the padded fabric may be immediately plunged into a heating chamber at from about 300 to about 350xc2x0 F. This is an important commercial aspect of the invention as it enables continuous processing on a commercial scale at speeds of 5-50 yards per minute. It must be appreciated, that this process is designed for commercial applications which are demanding in that the process must be commercially viable.
This may also be accomplished by curing at a low temperature with an active catalyst. It is also possible to use any combination of techniques which prevent the substantial loss of formaldehyde during the curing. For example, a low temperature may be used in combination with an aqueous formaldehyde solution. It would also be possible to use a pressurized system wherein the pressure is greater than atmospheric, thereby preventing the substantial loss of formaldehyde before the formaldehyde crosslinks with the cellulosic fiber-containing fabric being treated.
Rayon fabrics treated by the process of the present invention contain 6000+ ppm after treatment but before steaming or cleaning the treated fabric.
It is known to add to the rayon containing fabric a polymeric resinous additive that is capable of forming a soft film. For example, such additives may be a latex or fine aqueous dispersion of polyethylene, various alkyl acrylate polymers, acrylonitrile-butadiene copolymers, deacetylated ethylene-vinyl acetate copolymers, polyurethanes and the like. Such additives are well known to the art and are generally commercially available in concentrated aqueous latexform. Such a latex is diluted to provide about 1 to 3% polymer solids in the aqueous catalyst-containing padding bath before the fabric is treated therewith. One known softener which was virtually the softener of choice in the durable press process using resin treatment or formaldehyde crosslinking was high density polyethylene, Mykon HD. It has been unexpectedly discovered that the substitution of a silicone elastomer for high density polyethylene significantly reduces the loss in tear strength of the treated fabric after washing as well as providing better control of the process as may be seen from the examples. The importance of good control of the process is essential to a commercially viable process to provide a consistent product from run to run which is not adversely affected by variations in atmospheric pressure, humidity and the like.
As the rayon fiber-containing fabric which may be treated by the present process there can be employed various rayons which are made by any of the known processes including the viscose and cuprammonium processes. Rayon produced by the Lyocell process may also be treated effectively by the process of the present invention. Other fibers which may be used in blends with one or more of the above-mentioned rayons are, for example, polyamides (e.g., nylons), polyesters, acrylics (e.g., polyacrylonitrile), polyolefins, polyvinyl chloride, and polyvinylidene chloride. Such blends preferably include at least 35 to 40% by weight, and most preferably at least 50 to 60% by weight, of rayon.
The fabric may be a resinated material but preferably it is unresinated; it may be knit, woven, non-woven, or otherwise constructed. After processing, the formed wrinkle resistant fabric will maintain the desired configuration substantially for the life of the fabric. In addition, the fabric will have an excellent wash appearance even after repeated washing.
This invention is not dependent upon the limited amounts of moisture to control the crosslinking reaction since the crosslinking reaction is most efficient in the most highly swollen state of the cellulose fiber. Lesser amounts of moisture may be used but are less preferred.
However, the silicone elastomer is preferably present in a sufficient amount to reduce the loss of tensile and tear strength in the fabric normally associated with the treatment of the same fabric in a prior art treatment process which may include the use of other softeners. The formulation and process of the present invention may be adjusted to meet specific commercial requirements for the treated fabric. For example, formaldehyde and the catalyst concentration may be increased to provide better treatment; then the concentration of the softener is also increased to combat the loss of tear strength caused by the increased amount of catalyst used in the process. This lends itself to computerized control of the systems for treating various fabrics and allows variation in the treatment of different fabrics, which is another advantage of the process of the present invention.
While simple emulsified silicone oils are known as silicone softeners and have found some use in fabric treatment, they suffer serious disadvantages in having a strong tendency to produce non-removable spots. However, the particular silicone elastomer used in the process of the present invention completely overcomes these problems.
Fabrics to be treated in accordance with the present invention are immersed in a solution to provide a pick up or on the weight of fabric (OWF) of about 14-20% formaldehyde, 3-10 % of catalyst, and optionally 1-10% of the silicone elastomer. This requires a pickup of about 50 to 100% or more by weight of the aqueous formulation to achieve the above stated percentage of reactants on the fabric. The curing temperature may be about 350xc2x0 F. In fact, the padded fabric may be plunged into a oven or heating chamber at 350xc2x0 F.
The formaldehyde concentration may be varied as would be appreciated by one of ordinary skill in the art. The process includes the use of formaldehyde in the form of an aqueous solution having a concentration of about 14% to 20%, by weight.
The preferred formaldehyde concentration on the fabric is from 15% to 18% based on the weight of the fabric (OWF).
The catalyst which may be used in the process may be selected from any of the known acid catalysts conventional to the art which includes fluorosilicic acid for mild reactions and is applicable to blend fabrics. A group of catalysts which may be used in the present invention include those described in U.S. Pat. No. 3,960,482, the entire disclosure of which is herein incorporated by reference and which include acid catalysts including acid salts such as ammonium, magnesium, zinc, aluminum and alkaline earth metal chlorides, nitrates, bromides, bifluorides, sulfates, phosphates, and fluorborates. Magnesium chloride, aluminum and zirconium chlorohydroxide and mixtures thereof may also be used.
Water soluble acids which function as catalysts in the present process include both inorganic and organic acids such as sulfamic acid, phosphoric acid, hydrochloric acid, sulfuric acid, adipic acid, fumaric acid, citric acid, tartaric acid and the like may also be used. The catalysts may be used alone or in combination as can be readily determine by one of ordinary skill in the art.
On heavyweight, all-rayon fabrics, or shirting fabrics, a catalyst such as magnesium chloride spiked with citric acid can be used, which is a commercially available catalyst, Freecat LF. Freecat No. 9, is another magnesium chloride catalyst which contains aluminum/magnesium chloride. These catalysts are available from Freedom Textile Chemicals.
During the crosslinking reaction at the curing stage, moisture is given up from the fabric as the crosslinking occurs, resulting in a decrease in the moisture content of the fabric. Of course, water is not allowed to be present in so much of an excess as to cause the catalyst to migrate on the fabric.
Catalyst LF is a particularly active or xe2x80x9cHotxe2x80x9d version of the magnesium chloride catalyst used in conventional formaldehyde treatment process of cotton and it contains magnesium chloride salt and an organic acid, such as citric acid to boost the acidity. Other acids may also be used. Catalyst LF was developed to cure the hard-to-react low formaldehyde resins. Oddly enough, one would expect that since it is more acid than Catalyst No. 9, (magnesium chloride only) that it would cause greater damage and more strength loss. This is not the case, this catalyst more often than not produce higher treatment and better strength.
All test results reported in the following examples were obtained by the following standard methods:
1. Appearance of Fabrics after Repeated Home Laundering: AATCC Test Method 124-1992
2. Tensile Strength: ASTM: Test Method D-1682-64 (Test 1C)
3. Tear Strength: ASTM: Test Method D-1424-83 Falling Pendulum Method
4. Shrinkage: AATCC Test Method 150-1995
5. Wrinkle Recovery of Fabrics: Recovery Angle Method: AATCC Test Method 66-1990 which provides the DP value.
In determining the DP value for the fabrics, a visual comparative test is performed under controlled lighting conditions in which the amount of wrinkles in the treated fabric is compared with the amount of wrinkles present on pre-wrinkled plastic replicas. The plastic replicas have various degrees of wrinkles and range from a value of 1 DP for a very wrinkled fabric to 5.0 DP for a flat wrinkle free fabric. The higher the DP value, the better. For a commercially acceptable wrinkle free fabric, a DP value of 3.5 is desired but rarely achieved. As would be appreciated by one of ordinary skill in the art, the difference between a DP of 3.50 and 3.25 is significant. At DP 3.50 all wrinkles are rounded and disappearing. At DP 3.25 all wrinkles are still visible and show sharp creases. The goal for commercial acceptance for a cotton fabric is a DP of 3.50 with a filling tensile strength 25 pounds and a filling tear strength of 24 ounces. (Prior to this invention there was no DP for rayon since it could not be treated by formaldehyde DP processes). Of equal or even greater importance to these properties is that the process must be consistently reproducible on an industrial scale.
Moreover, shrinkage control is very important property and DP values which would not be acceptable for treated cotton become acceptable for rayon provided that shrinkage is controlled.
In all of the following examples a non-ionic wetting agent was used as is conventional to the art. The wetting agent was used in an amount of about 0.1 % by weight. The wetting agent used in all of the examples was a trimethyl nonanolethoxylate such as Union Carbide Tergitol TMN6. The wetting agent is used to cause complete wetting by the aqueous treating solution of the fibers in the fabric.
All of the samples were run on rayon containing fabrics. The normal industry standard for tear and tensile strength for a rayon shirting fabric is characterized by having a filling tensile strength of at least 25 pounds. The reaction conditions and test results are set forth in the tables.
The silicone elastomer was the commercially available dimethyl silicone emulsion sold by General Electric with a product number SM2112. This material is added as an opaque white liquid which contains from 24-26% silicone elastomer, has a pH of from 5.0-8.0 and is readily dilutable with water. Another commercially available silicone elastomer is Sedgefield Elastomer Softener ELS.
The catalysts used in the treatment process was obtained commercially as Catalyst LF which is an aqueous solution of magnesium chloride and citric acid.
Formaldehyde was in the form of an aqueous solution which was prepared from commercially available Formalin which is a 37% aqueous formaldehyde solution.
As is conventional in the art, all percentages given in the examples and tables are based on the product or chemicals as receive from the manufacture. The percentage is weight percent and in most instances is based on the weight of fabric being treated, except for the wetting agent which is added as a weight percent of the bath from which it is applied. The following examples are being presented not as limitations but to illustrate and provide a better understanding of the invention.
The amount of pick up of the treating solution from the bath by the fabric was determined by running the fabric through a padding bath containing only water and then through the squeeze rollers. The weight of a specific amount of dry fabric is determined and compared to the same amount of fabric after going through the padding bath and squeeze rollers. This amount of pick-up is expressed as percentage pick-up. For example, 90% pick up means that the fabric picks up 90% of its original weight after moving through the padding bath and through the squeeze rollers. Obviously the amount of pick-up will depend on how fast the fabric moves through the bath and the nip between the rollers. These parameters may be adjusted to control the amount of pick-up which in turn controls the concentration of chemicals in the padding bath to control the percentage of chemicals which are on the weight of the fabric. The techniques for making these adjustments are well known in the art and one of ordinary skill in the art would appreciate that it is necessary to know the amount of pick-up so that the amount of chemicals on the weight of the fabric (OWF) can be determined and thereby control the reaction on the fabric and obtain the desired results.

Rayon fabric with substantial shrink-resistant properties


A swatch sheet which is thin and pliable used for testing paint samples allows for paint to be placed on the viewable surface and prevents curling of the surface. A unique combination of a latex impregnated saturated paper, an acrylic microsphere adhesive and a release liner are provided, allowing for a substantially thin and pliable swatch to be applied on a flat or any other contoured or corner surface and be easily removed therefrom.

This invention relates to a new and improved system for allowing people to utilize a self stick sheet of paper or swatch, to which paint is applied to test paint samples and see how the color works in the exact space or multiple spaces to which the swatch or swatches are attached.
Selecting appropriate paint samples for painting home and offices and other places is often difficult because the paint sample in the store often is misrepresentative of how the paint will actually look on a wall at a specific location in view of the light and other environmental conditions existing thereat.
There exists in the prior art a patent application filed by Julie Boney, Ser. No. 11/827,645, entitled Portable Apparatus for Visualizing and Practicing Wall Finishes, Publication No. US 2008/0014561, filed Jul. 12, 2007. This patent application describes a product in which the consumer is enabled to visualize and practice color, finish technique or texture by applying paint to a primed first surface with a second rear surface permitting the substrate to be attached to a flat mounting surface, such as a wall.
A problem with this and other prior art is that merely using a substrate with a primed first surface and a second surface having a means to secure the substrate to a mounting surface produces a product which tends to curl especially at its edges. In order to eliminate such curl, one approach in the prior art is to use significant adhesive along the edges, but such an approach interferes with the ability of the prior art devices to easily be removed and repositioned, as desired. Additionally, since the curling occurs because of the interaction of the paint on a surface, the prior art does not effectively deal with this problem.
The product of this invention can be sold in sheets of various sizes or in rolls, and in whatever form a manufacturer desires. Its intended use is that the consumer will paint on the paper anywhere and place the swatch sheet in an area reasonably proximate to the location where the paint sample will be used. Additionally, the sheet could be placed on a wall without paint and the paint can be applied while on the wall. In either case, the consumer has to opportunity to observe how the paint works in the specific location desired and remove the swatch from the wall after the sample is observed, and the swatch can be removed and reapplied elsewhere.
Applicant has addressed the above curling problem by providing a stay flat sheet which can accept paint and which controls absorption and prevents paint passing through the painted surface and a self-stick adhesive rear surface attached to a liner, so that paint is applied while the liner is attached to the swatch. The liner is thereafter removed, permitting the painted stay flat sheet to be placed on a wall or wherever appropriate. It will remain flat and be removable to be repositionable elsewhere as desired with no residue left on the wall.
A unique aspect of the present invention is the provision of a stay flat sheet which prevents curling when the sheet is painted and subsequently attached to a wall surface. The novel sheet is thin enough so as to be pliable, bend into and around corners, around moldings and otherwise be adaptable to almost any uneven surface to which paint is to be applied. The swatch sheet of this invention is pliable in orthogonal directions.
In accordance with the present invention, paint is first applied to the sheet by the consumer, and the release liner is removed from the rear of the sheet transferring adhesive to the rear face of the sheet allowing the sheet to be placed flat against a wall, yet be removed and repositioned elsewhere as desired.
The stay flat sheet may either be of a conventional stay flat paper product, not used for this purpose or any other stay flat sheet which has similar characteristics of preventing paint from migrating through the painted surface. The stay flat sheet, preferably, comprises a latex impregnated saturated paper which controls absorption and does not allow paint to pass therethrough. Therefore, when paint is applied, as taught by this invention to the swatch, the swatch product will not curl. Such stay flat paper conventionally is used in the printing processes, and the present invention takes advantage of such properties to prevent such curling.
The stay flat sheet further incorporates a rear adhesive and release paper. The removable swatch sheet of this invention further has a rear surface of the stay flat sheet to which is applied an acrylic microsphere adhesive and a stay flat release liner, preferably generally known as a standard 50 lb stay flat liner. The release liner is removed from the rear surface, and the acrylic microsphere adhesive remains on the rear of the stay flat sheet permitting easy applying of the sheet to any surface as desired and easy removal therefrom.
The adhesive is an important element of this invention in that it must be such so that when the release liner is removed from the rear surface, the adhesive is transferred to the rear surface of the resultant sheet so that the sheet can be placed flat on a wall or surface, removed therefrom and repositioned in any other location.
This invention has a number of advantages. First of all, the stay flat sheet can be applied in situ to interior or exterior surfaces and on surfaces which are not only flat but also corners due to the relatively thin and pliable nature of the invention. It will stay flush to the wall so that it appears as part of the wall and one viewing how the color works, in situ, has the best vantage point for such observation.
A consumer or designer can check multiple colors at one time, comparing them in an easy and simple fashion in situ so as to make decisions on color coordination or other aspects of situations in which painting is required.
The present invention may also include a place on the back of the liner for the customer to initial approval and for any person working with the customer such as a decorator or designer to also sign an approval so as to maintain paper records of color choices made as projects proceed.
It is also possible that the swatch could be painted at any location, and a decorator or designer could send multiple variations to be tried in situ by the consumer without the decorator or designer needing to travel and to physically be present when such swatches are applied.
While the present invention is described for checking paint colors in situ, such a non-bleed top surface could be used for more frivolous purposes, such as receiving crayon designs, glitter, glue, pen and pencil drawings, all of which can be suitably applied to the top surface without bleeding therethrough and attractively attached wherever desired and, yet, may be simply removed from the surface to which the swatch is attached.
In addition to the Boney patent application above, other prior art documents are US Patent Application Publication 2007/0122612 to Young et al.; US Patent Application Publication 2002/009221 to DaRif et al.; US Publication 2003/0032907 to Lerner et al.; US Patent Application Publication 2008/0014561 to Boney; and U.S. Pat. Nos. 4,379,696 and 4,061,521 to Lerner. All such prior art is incorporated herein by reference.
It should be understood that the preferred embodiment was described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly legally and equitably entitled.

This patent is subject to a terminal disclaimer.

Repositionable self stick paint swatch for testing samples of paint on a wall


An improved analog meter is provided having no moving parts. This meter comprises a tapered resistor device having a tapered, electrically resistive element which develops a non-uniform temperature profile on electrical energization and a heat sensitive element operatively associated with the tapered resistive element. The heat sensitive medium employed is a reversible medium which either undergoes a change in color or contrast when heated to an appropriate temperature and when viewed under appropriate illumination. A method of metering employing this device is also disclosed.

This invention relates to metering devices and more specifically to a novel analog metering device having no moving parts.
Historically analog meters have been the mainstay of the meter measuring market by virtue of the fact that they involve low incident cost, are reliable, simple to manufacture, and are capable of supplying a continuous source of readings which are conventionally acceptable and desirable to those who employ them. The problems associated with the use of such conventional analog meters include: their inability to withstand rugged applications; and their inaccuracies when utilized in certain applications. With the advent of digital type devices the art became accustomed to direct readout devices which were more rugged than digital devices and therefore in most instances more dependable by virtue of the fact that they did not have moving parts and consequently required substantially less maintenance. However it is also well known that initially there was a great disparity in cost as between the analog and digital meters, i.e., initially digital meters were far more costly than analog meters, however during the growth and development of such technology this cost factor has become less pronounced and therefore digital meters are becoming more and more acceptable for many and varied applications. There are recent indications however that the measuring world seems to be reverting in substantial numbers back to the analog type devices for a number of reasons among which are: better readability with respect to visually observing trends and having an appreciation of relative magnitude of the measurement being made which is not possible with digital type meters in addition to the ever prevalent cost savings.
In response to this continuing need for analog type meters there has been made available commercially a number of analog meters which have no moving parts but which employ digital technologies to produce what appears to be analog indication in a metering type application. These hybrid devices are found to involve exhorbitant costs, and complexity of manufacture compared to either of the existing conventionally known analog and digital meters. There therefore seems to be a demonstrated need for continuing analog capability which has manifested itself in the marketplace in the form of a hybrid type meter having the aforementioned disadvantages.
There is therefore a demonstrated need to provide improved analog devices having no moving parts which will involve less maintenance, less cost of manufacture, more reliability, yet will still provide the technician or observer with the desirable analog type readings as above referred to.
It is therefore an object of this invention to provide a novel analog metering device devoid of the above noted deficiencies.
Yet another object of this invention is to provide an economical and easily maintainable analog novel metering device.
Yet still another object of this invention is to provide an analog metering device substantially having the advantages of digital type meters.
Yet still another object of this invention is to provide a novel analog metering system having no moving parts.
Again another object of this invention is to provide a novel metering system which is compact, easy to manufacture, and inexpensive to maintain.
Yet still another object of this invention is to provide a novel metering system which eliminates the need for complicated and expensive hybrid metering systems.
These and other objects of the instant invention are accomplished generally speaking by providing a tapered resistor element positioned on an insulating substrate which is suitably bonded to a heat sink. The tapered resistor element is then overcoated with heat sensitive media comprising materials which can be made to undergo a change in color or contrast when heated to an appropriate temperature and when viewed under appropriate illumination. Thus it is seen that now with the advent of tapered resistor technology innovative meters which are devoid of the deficiencies noted in both prior art digital and analog meters are now possible.
For example in U.S. Pat. No. 3,149,281 there is disclosed an electroluminescent voltage metering device having no moving parts as in the case of a tapered resistor metering device. However, there are significant distinguishable factors which are present and should be properly noted in order to properly define at least in part some of the advances made in the art: the device of the reference is far more complicated; it is restricted to the use of a certain phosphor or phosphors; and it would be far more expensive and complicated to manufacture.
This device generally comprises an apparatus for indicating the magnitude of an electric voltage in which two electrically conductive layers of which at least the one is optically transparent displays a range in the electroluminescent substance. At least one of these coatings has an electrical resistance of such a high value that upon application of a voltage at the one end of this resistance a light emission will at first substantially appear at this point and which with increasing voltage will continuously extend to further surface areas of the luminescent capacitor.
According to the invention a sharp boundary between the luminesced and the nonluminesced indicating area may be achieved by positioning between the two conductive coatings, an additional voltage dependent layer whose resistance is changed or varied abruptly at a predetermined voltage level. It is particularly advantageous to employ a material, such as cadmium sulfide which has the property of providing a voltage dependent resistance layer according to the patent.
In U.S. Pat. No. 3,244,979 a voltage indicating apparatus employing electroquenchable phosphor layers or layer is disclosed. As stated therein a layer composed of either of the phosphors cadmium sulfide and zinc cadmium sulfide is responsive to ultraviolet radiation incident thereon to emit visible light. The intensity of the light emitted by any region of such a phosphor layer can be reduced i.e., the phosphor can be quenched by applying a reverse biasing potential; a potential negative with respect to that of said region; to a rectifying connection to position over said region. Although the invention is not limited by any theory, the following is believed to be the explanation for this quenching. The aforementioned phosphors are n-type semiconductors which are excitable by ultraviolet radiation to produce whole electron pairs and emit visible light when these whole electron pairs recombine. However application of reverse biasing potential to a rectifying connection positioned over a region of the phosphor layer establishes an electric field within said region which attracts many of the holes generated by the ultraviolet radiation toward the rectifying connection, repels an equivalent number of electrons in said region away from the rectifing connection, and thus separates the holes and electrons in said region. This separation reduces markedly the number of recombination of holes and electrons within said region and therefore reduces markedly the intensity of visible light emitted thereby in response to ultraviolet radiation.
The voltage indicating apparatus of the invention comprises a layer of such an electroquenchable phosphor and conductive layers applied to opposing surfaces thereof in at least partial juxtaposition. One of these conductive layers is translucent to exciting radiation for example ultraviolet light. One is translucent to visible light emitted by the phosphor layer and one provides a rectifying connection to the phosphor layer. To excite the phosphor to emit visible light, means for example an ultraviolet emissive substance are provided for supplying radiant energy to the phosphor layer by way of the conductive layer translucent thereto. In addition means are provided for establishing a potential gradient along one conductive layer and for applying a potential to be measured to the other conductive layer. If this potential is intermediate to the minimum and maximum potentials applied to the opposing conductive layer, one region of the area rectifying connection provided by one or each conductive layer will be reverse biased, and concurrently another region thereof will be forward biased. The position of the boundary between the reverse biased and forward biased regions i.e., the position at which opposing portions of the two conductive layers are at the same potential, is determined by the magnitude of the applied voltage to be measured. The reverse biasing potential quenches only the portion of the phosphor layer lying beneath the reverse bias portion of the rectifying connection. Accordingly the position of the boundary between the luminesced and quenched areas of the phosphor layers indicates the magnitude of the applied voltage as the patent teaches.
Now with the advent of tapered resistor technology innovative meters which are far less complicated that those stated in the above patents and others have now been made possible.
Thus more specifically it can be seen that a meter employing such tapered resistor elements may be provided as follows: a tapered resistor element comprised of for example a nichrome tapered film is fabricated on an insulating substrate for example a borosilicate glass which is suitably bonded to an aluminum heat sink. A heat sensitive medium is then applied over the tapered resistor element for example, a cholesteric liquid crystal film is applied at least over the tapered resistor element. The particular cholesteric liquid crystalline material is chosen for conventionally known properties of such crystals which include providing a visible color change when heated to a specific temperature above ambient. The terminals of the tapered resistor are then connected to a current source to be measured. When the tapered resistor element is energized as explained above there is produced a temperature gradient and concurrent color changes in the cholesteric liquid crystalline material thus giving the meter reading.
Any suitable resistive film may be employed in the tapered resistor metering device of the instant invention. Typical resistive films include chromium, nichrome and nickel thin films as well as laminated foils of nichrome (a 80 Ni 20 Cr alloy), monel (a Cu,Ni alloy), Inconel (an alloy of nickel and chromium) on stainless steel. Any suitable insulating substrate may be employed in the metering system of the instant invention. Typical insulating materials include borosilicate glasses, ceramics, epoxy/glass composites, silicone rubbers, polyimides and polyethylene terephthalate.
Any suitable reversible material which can be made to undergo a change in color may be employed in the system of the instant invention. Typical materials which exhibit reversible color changes include a cholesteric liquid crystalline material, and Cu.sub.2 HgI.sub.4, and intrinsic semiconductors including amorphous semiconducting glasses.
Any suitable material which undergoes a change in contrast when heated to an appropriate temperature and when viewed under appropriate illumination may be employed in accordance with the system of the instant invention. Typical materials which undergo a change in contrast at an appropriate temperature when viewed under appropriate illumination include: for example, thermally quenched phosphors, such as Radelin #1807, made by the U.S. Radium Corporation can be mixed with a suitable binder and made into a slurry which can be sprayed over the tapered resistance element to form a relatively thin film on the order of for example, 3.times.10.sup.31 3 cm. The resultant film is found to fluoresce with a yellow light when illuminated with a long wavelength ultraviolet source. If the phosphor is then heated, the fluroescence is quenched and the phosphor turns dark.
Now with the advent of tapered resistor technology inexpensive analog meters may be provided which provide extremely desirable properties of both analog and digital meters known to the prior art. These devices incorporate and employ tapered resistance elements which develop a non-uniform temperature profile on electrical energization and are interacted after being energized with selected heat sensitive media to provide a number of very useful effects and devices which may be employed in a great many measuring applications as hereinabove described with ease, simplicity and greater economy than heretofore possible. The basis for this technology, the tapered resistor element is more specifically defined in U.S. Ser. No. 747,167 filed concurrently herewith (D/75554) which is hereby respectfully incorporated by reference.
Generally described therein, a conventional resistor device is seen to be a resistive film having a uniform thickness which has been formed into a resistor of a specified width and length. This film is then placed on an insulating substrate which is bonded to a heat sink. When an electrical current I is passed through the resistor the production of Joule heat causes a steady state temperature above ambient .beta.T which if thermal fringing effects are neglected may be theoretically defined by the relationship ##EQU1## in which d.sub.s and k.sub.s are respectively the thickness and thermal conductivity of the substrate and .rho..sub.s is the sheet resistivity of the resistive material measured in ohms/square. (Note: .rho..sub.s =.rho./d where .rho. is the bulk resistivity of the resistive material.) It is readily seen from this illustration that since the width of the resistor is uniform the local power dissipation and hence the temperature rise is also uniform so that no temperature gradient is established and the unique and utilizable effect of the device of the instant invention is not realized.
However, as is seen in FIG. 2 of U.S. Ser. No. 747,167, filed concurrently herewith (D/75554), a device may be provided including a resistive film which significantly has a varying width in the horizontal plane while the thickness remains uniform. This film may be placed on an insulating substrate 2 which in turn is bonded to a heat sink 3. Now it is seen that the width of the resistive element 1 is a monotonically increasing function of position along the length of the element or in simple terms the resistive element is tapered. In the event the slope of the taper is gradual over distances comparable with the substrate thickness, equation 1 recited above will still be applicable for a first approximation. When a tapered resistor is energized the local power generation will vary along the length of the resistor so that points of prescribed temperature rise can be made to move along the tapered resistor by varying the current flowing through the device.
Although the non-uniformity of the width of the resistive film 1 may vary in any suitable fashion, it is assumed for purposes of this discussion that the taper is linear as is seen in FIG. 2 of U.S. Ser. No. 747,167 so that the following relationship is theoretically true: w=w.sub.o +bx .phi.<x<1 (Eq. 2) in which w.sub.o is the width at the narrow end of the tape, b is the slope of the taper and x is the distance along the resistor measured from the narrow end. Assuming that the tapered resistive element is in contact with for example a thermographic substance which undergoes a color change when heated to the temperature T' or above as the current is increased in the tapered resistor a color line of x' will be drawn. The length of this line may theoretically be derived as follows: the temperature differential .DELTA.T' is defined as .DELTA.T'=T'-T.sub.amb, where T.sub.amb is the ambient temperature. Combining equations 1 and 2 yields the relationship between the applied current and the distance x' over which the tapered resistor will be heated to temperature T' or above, i.e., ##EQU2## It is seen that when w.sub.o is greater than zero no region of the taper will be hotter than T' for currents given by


In arrangement for supporting a counter pressure plate of a shaft-like surgical clamp suturing instrument for establishing a circular seam, a shaft-like clamp suturing instrument having at its distal end a support and guide structure and a one-piece support structure axially movably supported on the support and guide structure and having a support portion extending normal to the shaft section and releasable engaging a back-pressure plate in a position where the back-pressure plate is in axial alignment with the shaft section.

The invention relates to an arrangement for a functional support of a counter-pressure plate for a shaft-like surgical stapling instrument, particularly a laparoscope VBG (Vertical Band Gastroplastic) according to Mason, wherein a hole has to be punched into the front and the rear stomach walls which is done using a circular stapler.
With such laparoscopic surgeries, a stapler provided with a thorn is pushed from the front toward the back or vice-versa through the front and rear stomach walls and then connected to a counter pressure plate. By way of this hole, the stomach fundus is separated and the exit is surrounded by a band so that it cannot expand. Because of large difficulties to join the counter pressure plate behind the stomach to the thorn of the stapler and the danger of injuring directly adjacent organs such as the pancreas or large vessels, this surgery is generally performed in an open surgical procedure. So far, it is performed laparoscopically only in a few centers worldwide.
With the surgical stapling instruments known so far from DE OS 3 300 768 and DE PS 3 301 713 for the interconnection of two organ walls, the connection between the thorn and the counter pressure plate depends essentially on the experience and the sense of touch of the surgeon and is possible reliably only by open surgery.
It is the object of the invention to provide for the laparoscopically experienced surgeon an appartus for a functionally correct support of a counter pressure plate for a rod-like surgical clamp suturing instrument like an aiming device which facilitates a simple and safe connection by the clamp suturing instrument or, respectively, the circular stapler and the counter pressure plate.
In arrangement for supporting a counter pressure plate of a shaft-like surgical clamp suturing instrument for establishing a circular seam, a shaft-like clamp suturing instrument having at its distal end a support and guide structure and a one-piece support structure axially movably supported on the support and guide structure and having a support portion extending normal to the shaft section and releasable engaging a back-pressure plate in a position where the back-pressure plate is in axial alignment with the shaft section.
With the arrangement according to the invention, the laparoscopically experienced surgeon receives a safe auxiliary device for a reliable interconnection of a stapler and a counter pressure plate behind the stomach. At the same time, the arrangement according to the invention provides for a design and construction, which prevents injuries to surrounding organs and vessels.
The device can be easily attached to shaft sections of circular staplers or clamp suturing instruments and preferably consists only of single-part support member which, because of its shape, can be easily inserted behind the stomach wall and can also be properly adjusted for an accurate alignment of the counter-pressure plate for the intended connection because of its adjustable mounting on the shaft section and the removable support member for the counter pressure plate.
In a preferred embodiment of the invention the support member has a clasp-like shape wherein the engagement section for the counter pressure plate is provided at a widened end. The clasp-like shape combines the advantages of a rounded profile structure, which provides for small chances of injuries and those of simple manufacturing.
Preferably, the support section for the counter pressure plate comprises two semi-circular sections including an at least partially form fitting reception area for the outer contour of the counter pressure plate. These measures provide for safe positioning of the counter pressure plate for the intended connection with the thorn, which is extendable from the stapler. Preferably, the semicircular sections can be spread apart against the force of a spring structure which force preferably also provides for engagement of the counter pressure plate in the support section in order to ensure, together with the form fitting engagement, the safe retaining of the counter pressure plate.
In a preferred embodiment of the invention, the support member includes a sled-like mounting section which can be attached to a complementary profile section of a support and guide structure mounted on a distal end of the clamp suturing instrument such that it is movable between at least two engagement positions and is removable from the support and guide structure. Such an arrangement permits the support structure to be moved behind the stomach while in a first engagement position in which it is located further removed from the distal end of the clamp suturing instrument. After reaching the predetermined operating position, the support structure can be moved closer to the distal end of the thorn of the stapler to which it is to be coupled. After the pressure plate and the thorn have been joined, the stomach walls have been moved together and the holes have been punched, the support member can be removed in a simple manner from the counter pressure plate by backsliding of the support structure. Then the support member can be removed from the support and guide structure and deposited for removal from the operation area.
The movable mounting section of the support member preferably includes two parallel clamping legs and horizontal transverse sections. Preferably, the movable section of the mounting member is provided with at least tow disengageable locking members for securing the rest positions formed on the support and guide structure. The locking members are preferably self-engaging members such as spring-loaded balls which are received in corresponding recesses formed on the support and guide structure.
For the attachment of the support and guide structure, preferably a two-part mounting sleeve, which can easily be mounted, is provided. It includes a shot mounting section and a profiled section for the mounting section. The two mounting sleeve parts include sections, which are in engagement with each other.
For the release and the movement of the mounting part, at least one yoke-like handling structure is provided.
To facilitate the removal of the support member, in accordance with another embodiment of the invention, the support member is provided, at its end opposite the engagement section, with a structure for the attachment of a pull member.
In accordance with still another embodiment of the invention, a surgical clamping device for forming circular sutures is provided. It comprises a one-piece support member with a sidewardly projecting portion, which forms at its end an engagement portion for the releasable engagement of the counter pressure plate. A guide structure, which is removably mounted on the device shaft, is provided for the positioning of the counter pressure plate. Particularly the coupling of the counter pressure plate and the clamp suturing instrument by means of a guide structure ensures that the counter-pressure plate is moved toward the pull member or, respectively, the clamp magazine in its proper position and that a proper adaptation of the counter pressure plate is provided with the pull member. The releasable connection of the guide structure to the device shaft facilitates the separate introduction of the guide structure and the device shaft of the clamp-suturing instrument by way of a trocar. The guide structure and the device shaft are than interconnected within the belly of the patient. The separation of the equipment shaft and the guide structure is necessary since the diameter of the trocar is generally only slightly greater than the diameter of the clamp magazine so that the insertion of the device shaft with the guide structure attached thereto is impossible for most applications.
In a preferred embodiment, the guide structure according to the invention comprises a guide means which may be coupled to the device shaft by a coupling, a guide tube which is axially movably supported in the guide means and a support structure arranged at one end of the guide tube for receiving the counter pressure plate. The coupling for the interconnection of the guide structure with the device shaft comprises a mounting portion which surrounds the device shaft and which is preferably a clamping sleeve, and a coupling plate for the connection of the guide means to the mounting portion. To facilitate the insertion of the device shaft into the belly of the patient through the trocar the mounting part and the coupling plate of the coupling may be pivotally interconnected by means of two parallelogram-like lever pairs such that the coupling plate can be pivoted toward the device shaft whereby the circumference of the clamp suturing instrument is reduced. To this end, preferably the surface contour of the coupling plate facing the device shaft is adapted to the surface contour of the device shaft such that the coupling plate abuts the device shaft in a form-fitting manner in the collapsed insert position.
The lever pairs of the coupling can be pivoted by means of a linkage or a tackle, which is connected directly to the coupling plate and which includes a handle and is supported on the device shaft or respectively, the operating handle of the clamp suturing instrument. If a tackle is used, it is advantageous if furthermore at least one return spring is provided for the return of the coupling plate from the insertion position in which the coupling plate is pivoted onto the device shaft to the extended operating position. The return spring is connected with one end either to the coupling plate or at least one lever pair. The other end is mounted to a mounting structure.
In another preferred embodiment, the coupling is returned to an operating position by means of two parallel return springs which are connected with one end to the connecting plate and with the opposite end to the mounting structure.
In a further embodiment, half of the coupling is connected to the device shaft and the support for the counter pressure plate is connected to the guide tube by way of lever pairs such that the pivoting of the lever pair results in an orientation of the counter pressure plate which is co-axial with the device plate.
In connection herewith, the lever pair assigned to the coupling may be two parallelogram levers which, in the axial direction of the device are disposed on top of one another and between the device shaft and the associated coupling half of the coupling, whereas the lever pair assigned to the support structure for the counter pressure plate is arranged at the end of the guide tube wherein the connecting arm axes at the guide tube are disposed on top of one another in the longitudinal direction of the guide tube.
To facilitate the insertion of the guide structure into the trocar, the counter pressure plate can be pivoted together with the support structure thereof by means of a lever pair connected to the support structure from an operating position in which it extends parallel to the axis of the guide tube to an insert position in which it is disposed co-axially with the guide tube, wherein a coupling pin arranged concentrically on the counter pressure plate is disposed between the lever pair.
In order to permit actuation of the lever pair assigned to the support of the counter pressure plate when the guide structure is inserted in the trocar, an operating linkage is disposed in the guide tube, which, with one end, is connected to one of parallelogram levers of the support for the counter pressure plate and, with the other end, to a hand operating structure for the manual operation.
To avoid an unintended movement of the support structure for the counter pressure plate out of the operating position spring means are provided on the guide and the adjustment linkage, which bias the adjustment linkage in a position corresponding to the operating position of the counter-pressure plate so that the counter-pressure plate can be removed out of the operating position only against this spring force.
In order to ensure proper operation of the guide structure, a connection with accurate relative positions of the guide structure and the coupling plate are required. In order to ensure that the parts to be joined are accurately positioned the guide structure includes a centering pin which cooperates with a correspondingly-shaped centering bore in the connecting plate.
The guide structure is then fixed to the coupling plate by means of spring clamps or by resilient engagement tongues disposed on the guide structure, which are received in corresponding engagement recesses of the coupling plate.
In order to ensure a safe connection of the coupling part of the guide structure, the front side of the guide structure is provided with an angled support member which projects beyond the contour of the guide structure. The support member is received in a correspondingly shaped recess of the coupling plate and accommodates the forces resulting from the engagement tongue or engagement spring mounting arrangement.
Alternately, a guide panel which extends beyond the outer contour of the guide structure may be arranged at two opposite surfaces of the guide sleeve which guide panels cooperates with a complementary guide surface at the connecting plate. The spring tongues or spring clamps are so arranged at the guide structure that the effective directions of the guide panels and the retaining springs are displaced by 90xc2x0. In connection with this spatial arrangement of retaining clamps and guide panels, it has also been found to be advantageous to utilize a U-shaped spring clamp and about V-shaped bent-over end sections at the ends of the spring arms.
In order to provide for a secure axial locking of the guide tube within the guide structure, the guide structure includes a spring-loaded engagement means, which is spring biased in radial direction and which cooperates with corresponding engagement recesses or marks on the shaft of the support structure. Preferably, the engagement means consists of an engagement ball, which is disposed in a radial bore in the guide and is engaged by a compression spring.
The guide tube is prevented from rotation by providing the guide tube with a shape other circular and the guide structure surrounds the guide tube in a form-fitting relationship. Preferably, the guide tube has an oval cross-section.
The support structure for the counter pressure plate is essentially annular and includes two radial clamping jaws which are connected by two shaft sections to the lever pairs so as to be pivotable about an axis which extends parallel to the pivot axis of the lever pairs.
Below, the invention will be described in greater detail in the reference to the accompanying drawings.

Arrangement for mounting a counter-pressure plate for a shaft-like surgical suturing device