US3542504A - Biocidal textile finishing - Google Patents

Description

United States Patent 01 fice 3,542,504 Patented Nov. 24, 1970 U.S. Cl. 8116.2 Claims ABSTRACT OF THE DISCLOSURE Biocidal properties are imparted to cellulosic textile materials, e.g., filaments, yarns, ropes, fabrics, etc., made of cotton, rayon, etc., by treatment with an inorganic or organic polybasic acid, salt or equivalent acid group reagent to fix acid groups in the fiber molecule and then with a biocidal metal or metal compound to form the corresponding metal salt fixed to the textile material.

FIELD OF THE INVENTION There is considerable interest in the development of textile finishes having the property of inhibiting the growth of any bacteria with which they become contaminated. Such finishes are particularly valuable where pathogenic bacteria are involved, since they help in preventing the spread of infection, and enable textile material to be used in hospitals without the need for frequent sterilization. A successful finish of this type should, however, have good resistance to repeated laundering, since the textiles will, in any case, require to be washed in order to remove accumulated dirt.

A number of proposals have been made for processes for making textiles bactericidal. Most of the processes have involved the use of organic bactericides, but, although the finished textile is initially efifectively bactericidal, it loses this property very rapidly on laundering. Improved fastness to washing has been obtained by the use of certain metals, usually in the form of coordination complexes with organic compounds, but the presence of metal-sequestering agents in the detergent compositions used in modern laundering practice rapidly breaks down these coordination complexes and the bactericidal effect is lost.

Another general approach to the problem of imparting biocidal properties to cellulosic fabrics has been to place insoluble salts of biocidal metals in the fabric by the use of some suitable technique that does not adversely affect the fabric strength or other desirable qualities. Historically, this was done by evaporation of an organic solvent solution of an oil-soluble metal salt in the fabric, e.g., copper naphthenate. More recently, precipitation techniques which form the insoluble metal salts on the fabrics have been developed. For example, U.S. 2,288,810 concerns the treatment of fabrics by metathetical reactions to deposit precipitates of water-insoluble cadmium salts of organic acids on the fabric. The precipitate may also be formed only from inorganic materials, e.g., see U.S. 2,856,330 which concerns complex copper pyrophosphate salts. Variations of this general procedure have also been developed using salts of special organic acids that may be applied to the fabric either from aqueous dispersions of the water-insoluble salt or by metathetical reaction, e.g., see U.S. 2,381,852 which concerns impregnation of fabrics with copper salts of alkyl substituted succinic acids. Since all of these methods deposit an insoluble biocidal com pound upon the surface of the fibers forming the treated fabric, the durability of the biocidal protection to laundering or other cleansing is limited since action of cleansing chemical plus mechanical working of the fabric serves in time to effectively remove the biocidal coating from the fibers.

Proposals have also been made for improving the durability of biocidal finish by creating some form of chemical bondage between a biocidal agent and the fiber substrate. For example, U.S. 2,749,256 impregnates cellulose materials with copper formate followed by heat treatment which is stated to produce a reaction with the cellulose, but no explanation is offered and it seems probable that a basic copper salt or oxide is formed within the fibers by the baking treatment.

Nothwithstanding the extensive research and development work that has been expended on the problem, the textile industry is in need of new improvements in the finishing of textiles by commercially useable operations that will create cellulosic fabrics having bactericidal and fungicidal properties which are highly resistant to the destructive effects of laundering or other cleansing. This invention contributes new advances of this type to the textile finishing art.

OBJECTS of acid groups chemically bound to the textile fibers.

(3) New biocidal finishes on textile materials consisting wholly or partly of cellulose and resistant to repeated laundering in the presence of metal sequestering agents.

(4) Improvements in the techniques of biocidal finishing of fabrics to provide improved fastness to washing of the biocidal properties of the finished fabric.

(5) New methods for biocidal finishing of fabrics in which the biocidal agent is not present simply as a coating or film upon the fabric or the fibers of which the fabric is formed.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

GENERAL DESCRIPTION These objects are accomplished in accordance with this invention through the use of methods of providing cellulosic fabrics with biocidal properties in which acid groups are chemically bound to the fiber molecules through an oxygen atom and then chemically combining with the resulting fixed acid groups a biocidal metal to form salt groups comprising the biocidal metal chemically bound to the fiber molecules of which the cellulosic fibers are formed.

The acid groups to which the biocidal metals are chemically combined may be introduced into the textile material formed at least in part of natural or regenerated cellulose and containing hydroxyl groups in a variety of ways in cluding the following:

-(1) Halogenated derivatives of mono and polybasic organic acids can be made to react with the hydroxy groups of the cellulose, in the presence of alkalies, to form cellulose carboxy alkyl ethers.

(2) Polybasic organic acids of suitable acidity can be made to react with the cellulose hydroxyl groups by direct esterification, in such a Way that one of the acid groups is esterified, while leaving an acid group free.

(3) Some polybasic inorganic acids can also be partial- 1y esterified with the cellulose hydroxyl groups in a similar manner. Owing to the high ionic strength of some of these acids and the marked degrading action which they have on cellulose polymers, esterification in these cases is carried out using special techniques.

The success of this invention is due in part to the discovery that certain types of acid groups, both inorganic and organic acid groups, may be fixed onto textile materials by reaction with hydroxyl groups contained in the fiber molecules and that then certain biocidal metals can be made to combine with these acid groups in such a way that the metal is only slowly removed on subsequent laundering even in the presence of metal sequestering agents. With the metal possessing biocidal properties and fixed in this manner to the fabric, textile materials so treated can be made effectively bactericidal and/r fungicidal and the finish will possess very good resistance to laundering.

By way of example, biocidal metals which may be advantageously used in these new fabric treating methods are silver, copper, mercury, lead, beryllium, antimony and cadmium.

In introducing acid groups by reacting a halogen derivative of an organic acid with a cellulosic fabric, it is most convenient to impregnate the fabric with an aqueous solution of the sodium salt of the halogenated acid, dry it at a moderate temperature and reimpregnate it with an aquedetergent solution:

G./l Soap 5 Soda ash 2 Sodium salt of ethylene diamine tetra-acetic acid 0.2

The washing procedure is repeated as many times as is desired.

EXAMPLES The new processes and resulting products can be further comprehended by reference to the following report of operations and results illustrating the invention. In these examples and throughout the remaining specification and claims, all parts and percentages are by weight unless otherwise specified.

Example 1 A plain-Weave cotton fabric 80/80, 30 /30 which has been bleached and mercerized was immersed in the following solutions, mangled to 100% pick-up, and dried at 70 C. The dried material was heat-treated under the stated conditions, washed in cold running water, then in 5 g./l. sodium carbonate solution for 2 minutes at 85 C. and again in cold running Water, squeezed and dried. The number of hydrogen ions per 100 anhydro glucose resigues in the samples were then determined as described elow.

ous solution of sodium hydroxide. In this condition, the wet cloth can be left to lie at room temperature for some time to allow the reaction between the cellulose and the halogenated acid to take place or the reaction can be speeded up by steaming the fabric or by drying it at an elevated temperature. The treated fabric is then wellwashed in water to remove unreacted reagents and dried.

In introducing acid groups by reacting a polybasic organic acid with a cellulose fabric, it is convenient to impregnate the fabric with an aqueous solution of the acid, dry it at about 100 C. and then heat-treat it at an elevated temperature. After this, it is well-washed in water to remove unreacted reagents and dried.

In introducing acid groups by reacting a polybasic inorganic acid with a cellulosic fabric, modification of the conditions used with polybasic organic acids is employed. Because of the high ionic strength of inorganic acids, severe degradation of the cellulose takes place if a fabric is heated with the acid alone and the reaction is best carried out in the presence of fairly high concentrations of a weak base such as urea. The fabric is impregnated with an aqueous solution of the acid and urea, dried at about 100 C. and then heat-treated at an elevated temperature. After this, it is well-washed in water to remove unreacted reagents and dried. This procedure has been described in British Pat. 649,642 in connection with the production of a flame-resistant finish. In the case of phosphoric acid, it has been found that a unique modification of this pro- Cadmium content (g. Cd/g. sample) Solution A B C D E Bactericidal activity (width of halo in mm.)

Solution A B C D E Number of washes:

It would appear that a minimum concentration of about 0.005 g. of cadmium per g. of cloth is necessary in order to make the material bactericidal to Staphylococcus aureus and this corresponds to about 2 hydrogen ions per 100 anhydro glucose residues of the cellulose chain; a lower limit for the number of acid groups which must be fixed to the textile material is given by this figure. On the other hand, in order to maintain this concentration of cadmium on the textile material after repeated laundering (say washes), an intial concentration of cadmium of about 0.02 g. per g. of cloth is required and this corresponds to about 8 hydrogen ions per 100 anhydro glucose residues. In practice, a minimum value of this order is preferred.

Example 2 A plain-weave cotton fabric, which had been bleached and mercerized was immersed in a solution of 12 g. sulfuric acid (98%), 63 g. urea and g. water, mangled to give a pick-up of 120%, dried at 100 C. and heattreated for 10 minutes at 170 C. The material was washed in cold running water, then in a 5 g./l. sodium carbonate solution for 2 minutes at 85 C., and again in cold running water, squeezed and dried. The treated material was then paded through a 0.5% solution of mercuric chloride, dried, washed off in cold running water and again dried. A portion of the treated material was washed in soap and soda for minutes at 93 C. and bactericidal tests made on the material before and after this laundering treatment. A halo of 5.5 mm. was shown by the unlaundered material and a halo of 4.0 mm. by the laundered material.

Example 3 A portion of cotton fabric as in Example 2 was immersed in an aqueous solution containing 16.5 gm. sodium hexametaphosphate and 59 g. of urea per 100 cc., mangled to give a pick-up of 100%, dried at 100 C. and heattreated for 10 minutes at 160 C. After this, it was washed in cold running water, then in 5 g./l. sodium carbonate solution for 2 minutes at 85 C., and again in cold running water, squeezed and dried. The treated material was then padded through a 0.5% solution of silver nitrate, dried, washed off in cold running water and again dried. A portion of the treated material was washed in soap and soda for 30 minutes at 93 C., and bactericidal tests made on the material before and after this laundering treatment. A halo of 2.0 mm. was shown by the unlaundered material and a halo of 1.5 mm. by the laundered material.

Example 4 Mercerized cotton cloth was immersed in a solution of 9 g. phosphoric acid (sp. gr. 1.75), 25 g. urea and 66 g. water, mangled to give a pick-up of 100%, dried at 100 C., heat-treated for 10 minutes at 160 C. and washed off in Water. Portions of the treated material were immersed in 0.5 solutions of (a) cadmium chloride, (b) mercuric chloride, (0) lead nitrate, and (d) copper sulfate for 30 minutes at room temperature and then washed ofi in cold running water to remove any unfixed metal salt. Separate samples of the treated material were then separately Washed in (1) 5 g./l. soap plus 2 g./l. soda ash, (2) 5 g./l. soap, 2 g./l. soda ash and 1 g./l. sodium hexametaphosphate, and (3) 5 g./l. soap, 2 g./l. soda ash and 0.2 g./l. sodium salt of ethylene diamine tetra-acetic acid, for 30 minutes at 93. Bactericidal tests made on the fabric samples after these various treatments gave halos of the following diameter:

6 Example 5 A spun viscose cloth was immersed in a solution of 8 g. phosphoric acid (sp. gr. 1.75), 60 g. urea and 32 g. water, mangled to give a pick-up of 100%, dried at 100 C., heat treated for 2 minutes at 170 C. and washed off in cold running water, then in 5 g./l. sodium carbonate solution for 2 minutes at C. and again in cold running water, squeezed and dried. The material contained 20.5 hydrogen ions per anhydro glucose residues. It was then immersed in 20 times its weight of a 0.1 N solution of cadmium chloride for 1 hour at room temperature and then washed for 10 minutes in cold running water and dried. A sample of the treated material was washed in 5 g./l. soap, plus 0.2 g./l. sodium salt of ethylene diamine tetra-acetic acid on a wash-wheel for 1 /2 hours at 60 C., using a. liquor to goods ratio of 10: 1. A halo of 16 mm. was shown by the unlaundered material and a halo of 9 mm. by the laundered material.

Example 6 The bactericidal effect of various metals absorbed onto mercerized cotton cloth containing 10 hydrogen ions per 100 anhydro glucose units, was evaluated by immersing the fabric in a solution of 9 g. phosphoric acid (sp. gr. 1.75), 25 g. urea and 66 g. water, mangling to give a pick-up of 100%, drying at 100 C., heat-treating for 10 minutes at 160 C., and washing off in water. The adsorption of the metal took place by immersing samples of the acid treated fabric in 0.5% solutions of a suitable salt of the metal for 30 minutes at room temperature, followed by washing in cold running water to remove excess metal-salt solution. The samples were washed in soap and soda at 93 C. for 30 minutes before examining the bactericidal properties.

Salt solution: Width of halo in mm. Silver nitrate 2.2

, Cupric sulfate 2.0 Mercuric chloride 6.5 Lead nitrate 1.5 Beryllium chloride 2.0 Antimony trichloride 3.0 Cadmium chloride 8.0

All the metals of the foregoing list exhibit bactericidal action, but some form heavily colored sulfides and staining of the fabric is liable to be produced from this cause, during use. For this, and other reasons, cadmium is preferred as a bactericidal metal for the purposes of this invention.

Example 7 An evaluation of the number of hydrogen ions per 100 anhydro glucose units of cellulose chain obtainable by treatment of cotton fibers was made with various acids as reported below:

(a) Mercerized cotton cloth was immersed in a 15% solution of sodium monochloracetate and then mangled to give a 100% pickup, dried and reimmersed in 25% sodium hydroxide solution for five minutes, preferably while stretched on a frame, and then washed 0E in water. Under these conditions, about 3 hydrogen ions per 100 anhydro glucose units were introduced into the cotton,

(b) Mercerized cotton cloth was immersed in a solution of 20 g. maleic acid in 80 g. of water, mangled to give a 100% pick-up, dried and heat-treated for 15 minutes at C. About 11.5 hydrogen ions per 100 anhydro glucose units were introduced into the cotton,

(c) Mercerized cotton cloth was immersed in a solution of 20 g. citraconic acid in 80 g. of water, mangled to give a 100% pick-up, dried and heat-treated for 15 minutes at C. After Washing off in water about 2.3 hydrogen ions per 100 anhydro glucose units were introduced into the cotton,

(d) Mercerized cotton cloth was immersed in a solution of 18.75 g. phospheric acid (sp. gr. 1.75), 37.5 g.

7 urea and 43.75 g. water, mangled to give a 100% pick up, dried and heat-treated for minutes at 160 C. It was then washed off in water. About 35 hydrogen ions per 100 anhydro glucose units were introduced into the cotton,

(e) Mercerized cotton cloth was immersed in a solution of 9.5 g. sulfuric acid (98%), 51 g. of urea and 39.5 g. water, mangled to give a 100% pickup and heattreated for 1 minute at 160 C. It was then washed off in water. About 3 hydrogen ions per 100 anhydro glucose units were introduced into the cotton, and

(f) Mercerized cotton cloth was immersed in a solution of 50 g. sodium hexametaphosphate and 100 g. water and mangled to a pick-up of about 80%. It was then heat-treated for 15 minutes at 160 C., washed off in water and dried. About 9.5 hydrogen ions per 100 anhydro glucose units were introduced into the fabric.

Example 8 Mercerized cotton cloth was immersed in a solution of 18 g. maleic acid, 52 g. urea and 30 g. water, mangled to give a pick-up of 100%, dried at 100 C, heat-treated for 10 minutes at 130 C., and washed off in water. The treated material was then padded through a 0.5% solution of lead nitrate, dried, washed off in cold running water and again dried. A portion of the treated material was washed in soap and soda for 30 minutes at 93 C. and bactericidal tests made on the material before and after this laundering treatment. A halo of 3.5 mm. was shown by the unlaundered material and a halo of 2.5 mm. by the laundered material.

In the foregoing examples, the determination of the number of acid groups which have been introduced into the textile material was performed by first immersing a sample of the treated material in a normal solution of hydrochloric acid at room temperature for 5 minutes, in order to ensure that all the introduced groups are present as the free acid, and then removing all traces of hydrochloric acid by a thorough washing in water. The sample of cloth was then dried and a. weighed amount of it immersed in an aqueous solution of 0.1 normal potassium iodate and 0.5 N potassium iodide for 1 hour at room temperature and the liberated iodine, which is proportional to the number of acid groups on the Weighed sample of cloth, determined by titration with sodium thiosulfate. The results are expressed in the form: number of hydrogen ions per 100 anhydro glucose units of the cellulose chain.

The determination of the bactericidal properties of the finish was carried out by the well-known Agar-Plate method, using Staphylococcus aureus as the test bacteria. For this, -20 ml. of a nutrient agar were innoculated with 1 ml. of a 24 hours-old broth culture of the bacteria and the mixture poured into a sterile petri dish. One inch diameter discs of the textile material were placed on the surface of the solidified agar and the assembly incubated for 24 hours at 37 C. The effectiveness of the bactericidal finish on the sample was assessed by measuring the width in millimeters of the growth-free clear zone or halo surrounding the disc of fabric.

DISCUSSION OF DETAILS The new methods of the invention are particularly suitable for finishing of textile materials formed in whole or in part of cellulosic fibers. However, the benefits of the new methods are contemplated for use with fabrics made of other textile fibers which may contain hydroxyl groups reactive with acids or acid containing reagents in accordance with the described procedures. The new methods are advantageously employed with fabrics made from cotton, linen, viscose rayon or mixtures of these as well as fabrics containing blended yams of cellulosic fibers and non-cellulosic fibers. Similarly, the fabrics treated by the new methods may be formed of mixtures of cellulosic fibers and non-cellulosic fibers, e.g., polyolefin, acrylic, modacrylic, polyester and equivalent fibers.

Textile materials treated in accordance with the methods may be in the form of non-woven fabrics, woven fabrics, knitted textiles or any other similar webs made up basically of thread-like fibers. In addition, the textile material may be in the form of loose fiber, yarn or the like which will be subsequently converted into fabrics or ropes, twine, cordage and the like.

The chemical reagent employed for creating acid groups fixed to cellulosic fiber molecules in accordance with the invention may take a variety of forms. As illustrated in the foregoing examples, such reagents may be selected halogen derivatives of organic acids, polybasic organic acids, polybasic inorganic acids and salts of polybasic inorganic acids.

A preferred method of fixing acid groups to the fiber molecules of which the cellulosic textile material is formed involves the use of polybasic caids. Three features govern the choice of acid for this purpose:

(1) The acid itself should be stable at the temperature needed to bring about the reaction with the cellulose,

(2) The dissociation constant of the first hydrogen ion of the acid should be great enough to allow reaction with the cellulose to take place in a reasonable time at a temperature which is not too high to cause substantial degradation of the celluolse, and

(3) The dissociation constant of another hydrogen ion should be considerably lower than that of the first hydrogen ion so that little or no reaction between the cellulose and this other hydrogen ion takes place under the conditions required to bring about a reaction between the cellulose and the first hydrogen ion. The attainment of these conditions and poly-basic acids suitable therefor can he readily determined by those skilled in the textile treatment art utilizing the general principles as stated and the method of determining number of acid groups which were introduced into the textile material as previously described. Although it mya be found that some acids outside these limits can be successfully employed, it has been found advantageous to utilize polybasic acids which are stable up to a temperature of at least 200 C. and which have a pK value for the dissociation constant of the first hydrogen of the acid at 25 C. not greater than 3.0 and the pK value of another hydrogen of the acid greater than about 4.0-.

Examples of polybasic acids for use in the new finishing methods include maleic, oxalic, citraconic, malonic, and phosphoric acids. Using the weak organic base technique as described, sulfuric acid may also be used.

Examples of halo-organic acids that may be used in the ether acid group type of finishing method previously described include monochloracetic, dibromosuccinic and equivalent acids. Salts of these acids with alkali metals or other bases may also be used for this purpose.

Concentrations of reagents and the reaction conditions may be varied and will be governed in part by the particular textile material being treated and the acid group fixing reagents employed. Optimum concentrations and other variables may be determined by simple testing using the test methods described above, or their equivalent, and the general principles as outlined. Introduction of between about 2 to 50 hydrogen ions per anhydro glucose units in the fiber molecules is advantageous. T0 attain this, elevated temperatures are preferably used with the polybasic acids or their salts, namely, 100 to 180 C. for times of treatment between about 1 to 30 minutes, shorter times generally being used the higher the temperature and/ or the lower the pK value of the acid.

Aqueous solutions of the acid fixing reagents are advantageously used and these can be of concentration between about 1 and 50 percent. With the inorganic acid group fixing reagents it is preferred that the solution also contain a weak organic base, e.g., a base having a pK value greater than about 10.0 such as urea. The concentration of such base in the treating solution should be substantial, e.g., 10 to 350 parts or even higher of base per hundred parts of water and, in terms of the acid fixing reagent, 2 to 30 parts of base for each part of the acid or acid salt.

The amount of treating solution applied to the fabric may be varied and will be controlled in part by the percentage of cellulosic fibers in the textile material, acid fixing reagent, etc. With solutions containing 1 to 50% acid or acid salt, a solution pick-up before the drying and heating operation of 50 to 120% is advantageous.

Conventional apparatus and application procedures may be employed for applying the treating compositions to the fabric or other textile material and commercially available equipment may be used for this purpose although special procedures and equipment may be employed if desired. Established padding or impregnating procedures are satisfactory and these may be carried out in standard texile processing equipment. Drying and heating as required may be accomplished on any standard drying drums, ovens or similar textile handling devices. In addition to padding or immersion of the fabrics in the treating solutions, it would be possible to apply them in any other suitable fashion such as spraying, roller coating or the like.

The new operations can be used in conjunction with other textile processing procedures if this appears desirable or advisable, taking into account the end use of the fabric. Obviously, if the textile material is treated in the form of yarns or filaments, the treatment will be succeeded by such operations as brading, rope twisting, weaving, knitting or the like. Conjunctive operations may also include water-proofing embossing, dimension stabilizing, pressing and the like. Application of other finishing and/ or treating agents can also be accomplished in conjunction with the new operations, e.g., application of sizing agents, softeners, lubricating materials, water-repellant agents, moth-proofing agents, mildew-proofing agents, dyes, pigments and the like.

CONCLUSION There has been presented a discussion of new methods for biocidal textile finishing to produce new fabrics, yarns, and other textile materials having improved properties in suflicient detail contemplated to enable those skilled in the art to carry out the methods and produce the new products. Treated fabrics to be obtained in accordance with the invention are characterized by bactericidal and fungicidal properties which have very good resistance to laundering even in the presence of metal sequestering agents. Such qualities make the new textile materials particularly useful in humid tropic environments Where biocidal attack on textile materials is relatively great although the new treated textiles can be used for any other purposes for which resistance to biocidal attack are known or may become known to be useful.

The embodiments of the invention in which an exclusive property or right is claimed are defined as follows:

1. A method of producing on a cellulosic fabric a bactericidal finish that is resistant to laundering with detergent solutions containing metal sequestering agents 'which comprises:

(A) chemically bonding phosphoric acid groups to fiber molecules of which the cellulosic fabric is formed by treatment of the fabric with phosphoric acid or a salt thereof,

(B) continuing such treatment to fix on said fiber molecules suflicient acid groups to provide at least eight hydrogen ions per anhydro-glucose units in the fiber molecules, and

(C) treating the resulting cellulosic fabric with a cad mium salt to combine cadmium with said acid groups fixed upon said fabric in a concentration of cadmium of at least 0.0-2 gram per gram of fabric.

2. A cellulosic fabric having a bactericidal finish that is resistant to laundering with detergent solutions containing metal-sequestering agents by cadmium metal chemically bonded to the fabric molecules in a concentration of at least 0.02 gram per gram of fabric by a method as claimed in claim 1.

3. A method as claimed in claim 1 wherein said chemical bonding is accomplished by esterification of hydroxy groups of said fiber molecules by heating the fabric in an aqueous solution of a water-soluble salt of phosphoric acid at a temperature between about 100 and C.

4. A method as claimed in claim 3 wherein said aqueous solution contains urea.

5. A method as claimed in claim 1 wherein step (A) is performed by immersing a fabric formed at least in part of cotton fibers in an aqueous solution containing 16.5 parts of sodium hexametaphosphate and 59 parts of urea per 100 parts of water, expressing solution from the impregnated fabric to give a solution pickup of 100% based upon the dry weight of the fabric, then drying the fabric References Cited UNITED STATES PATENTS 8/ 1948 Reid et a1. 424-132 10/ 1950 Ford et a1. 8-11 6.2

GEORGE F. LESMES, Primary Examiner J. R. MILLER, Assistant Examiner