US3558544A

US3558544A - Latex coatings for electrostatic and photoconductive purposes

Info

Publication number: US3558544A
Application number: US569301A
Authority: US
Inventors: Albert J Cole; George P Rowland
Original assignee: Firestone Tire and Rubber Co
Current assignee: Bridgestone Firestone Inc
Priority date: 1966-08-01
Filing date: 1966-08-01
Publication date: 1971-01-26
Anticipated expiration: 1988-01-26

Abstract

AN AQUEOUS LATEX COATING COMPOSITION COMPRISING AN INTERPOLYMER OF METHYL METHACRYLATE, BUTADIENE AND STYRENE AND HAVING DISSOLVED THEREIN FROM ABOUT 0.5 TO ABOUT 2.5 PERCENT BY WEIGHT OF THE SURFACTANT MIXTURE CONSISTING OF (1) A SALT SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL AND AMMONIUM SALTS OF ALKYL SULFATES, ALKYL ARYL SULFONATES AND MIXTURES THEREOF, AND (2) A SALT SELECTED FROM THE GROUP CONSISTING OF THE ALKALI METAL AND AMMONIUM SALTS OF FATTY ACIDS.

Description

Filed Au 1. 1966 Jan. 26,1971 A.J. coLE ETAL 35 85544 m commas FOBELECTROSTATICAND PHbTOCONDUCTIVE PURPOSES I zshep ts-shee tl i i i f v 1 I BUTADIE NE FIG. 1.

. I ALBERT 1 001.51 GEORGE B ROWLAND Jan. 26, 1971 ilA'rEx COATINGS FOR A. J. COLE ETAL ELECTROSTATIC AND PHOTOCQNDUCTiVE PURPOSES Filed Aug. 1. 1966 aboo . zsoo 1. I goo VOLTSQIACCEPTED 2- yShaets-Sheet I 2 r 4 e 8 IO l2 POUNDS /REAM ALBERT J. COLE GEORGE P. ROWLAND mvmons United States Patent LATEX COATINGS FOR ELECTROSTATIC AND PHOTOCONDUCTIVE PURPOSES Albert J. Cole, New Hanover Township, Pa., and George P. Rowland, Akron, Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio Filed Aug. 1, 1966, Ser. No. 569,301 Int. Cl. C08d 7/02; C09d 3/64 U.S. Cl. 26029.7 10 Claims ABSTRACT OF THE DISCLOSURE This invention relates to sheets coated with a resinous methyl methacrylate, butadiene and styrene interpolymer. More particularly, it relates to sheets useful in dry printing processes, i.e., electrostatic and Electrofax printing processes, and to processes for producing and using such sheets. This invention also relates to coating compositions useful for preparing sheets useful in electrostatic and Electrofax processes.

Electrostatic printing employs a sheet coated with a clear film, referred to hereinafter as an electrostatic sheet, which when subjected to a corona discharge in certain predetermined areas, accepts a portion of the charge in those areas, and holds it for a period of time sufficient for a visible image to be developed on .he sheet. The image is developed by depositing a toner (a pigmented, charged resin powder) on the surface of the coated sheet, which is attracted to those portions of the coating on which a charge has been imposed. The toner may be deposited by a so-called magnetic brus which is made by mixing the toner powder with iron particles (to give the toner the proper electrostatic charge by the triboelectric effect) and holding the mixture on a magnet. As this brush is swept across the coated sheet, the toner particles adhere to the charged areas while the iron particles are retained on the magnet. The sheet is then subjected to a temperature of approximately 150 C. for a short period of time to fuse the toner powder to the sheet.

The Electrofax process employs a sheet, commonly referred to as a binder plate, coated with a photoconductive material, usually zinc oxide, disbursed in a binder. The sheet is given a negative charge in the dark by corona discharge, and then exposed to an image projected through a lens system. Light from the non-image areas of the document copied causes the charge on the sheet to be dissipated in the corresponding areas, leaving on the sheet an electrostatic pattern that duplicates the image of the original. This image may be developed using Patented Jan. 26, 1971 the magnetic brush technique described above or by using a liquid development system which employs pigments particles suspended in an organic liquid. Using the liquid developer method, the developer is applied on the sheet either by dipping the paper in the developer or by spraying the developer on the sheet. The suspended pigmented particles cling to the charged areas of the paper by etectrostatic attraction and are held to it permanently, usually by a resin binder. After most of the liquid has flowed off the sheet the remainder is normally removed by blowing warm air across it.

In sheets employed in electrostatic printing processes it is essential that the coated sheet accept a static electric charge and hold at least part of it for a period of time sufiicient for the latent image to be developed.

Many polymers which would be acceptable for use as coatings for electrostatic sheets or as binder for binder plates exhibit the property of sticking to an adjacent surface (blocking) when stacked or wound in rolls. This property necessitates the inclusion of an anti-bl0cking agent in the polymer, and since many of the known antiblocking agentsare readily ionizable, the conductivity of the coating may be effected. Thus, it is apparent that it is desirable that the polymer used as a coating for electrostatic sheets, or as a binder for binder plates, be nonblocking.

At the present time, the most Widely used binder plates are made by coating an organic solvent solution of a resin containing a photoconductive material, such as zinc oxide, uniformly dispersed therethrough onto a paper backing. Electrostatic sheets are generally made in a similar manner, using similar organic solvent solutions absent the photoconductive material. Such paper sheets are potentially no more expensive than high grade magazine paper. However, due in part to the expenses inherent in using organic solvent systems, i.e., the expenses incurred due to the necessity of using special apparatus for solvent recovery and to minimize vapors and fumes, such relative low cost level has not been attained. Another disadvantage of organic solvent systems is the inherent fire hazard presented. Attempts have been made to eliminate the organic solvents and apply the coating in an aqueous system. Such attempts have usually resulted in films having drastically diminished electrical insulating properties, reduced charge acceptance and retention properties, or increased sensitivity to moisture.

It has now been found that electrostatic sheets and binder plates may be prepared using a novel aqueous latex as hereinafter described. The aqueous coating system may be handled in conventional paper machinery to apply the coating to the paper web, using conventional techniques for handling aqueous coating compositions. The novel aqueous latex of the present invention comprises an interpolymer of methyl methacrylate, butadiene, and styrene. Films formed from this latex exhibit a high degree of charge acceptance and retention, are nonconductive, relatively insensitive to moisture, and are essentially non-blocking. Another advantage of the latex of the present invention is that it may be formed using relatively small amounts of emulsifier.

In order to form a non-blocking film from the latex it is essential that the ratio by weight of methyl methacrylate to butadiene to styrene be selected so that the amount of each monomer falls within the shaded area of the ternary diagram of FIG. 1. By selecting monomer ratios so that they fall within the shaded area of the ternary diagram of FIG. 1, the resultant interpolymer will form a charge accepting, non-blocking film. The ratios defined by the shaded area of the diagram have been determined empirically. The diagram of FIG. 1 is self-explanatory; axis AC and point B represent 0% and 100% methyl methacrylate, respectively; axis AB and point C represent 0% and 100% butadiene, respectively, and axis BC and point A represent 0% and 100% styrene, respectively. Ratios of monomers falling above line DE tend to form interpolymers which exhibit blocking, while ratios which fall below line DE tend to form interpolymers which do not exhibit blocking. It should be appreciated that the line between blocking and nonblocking interpolymers is not a sharp one, thus explaining why part of the shaded area extends above line DE. The important consideration is to selecting monomer ratios which, when plotted on the ternary diagram of FIG. 1, will fall within the shaded area, thus assuring that a non-blocking, film-forming interpolymer will result. A preferred embodiment of the present invention is a latex in which the ratio by weight of methyl methacrylate to the combined Weight of butadiene and styrene is one to one, and the ratio by weight of butadiene to styrene is one to one.

The latex may be prepared merely by mixing the various monomers in the desired ratio with water in the presence of an emulsifying agent (surfactant) and polymerizing, following procedures and using equipment well known in the art. A polymerization catalyst may be used if desired as is known in the art. It is also possible to prepare a graft latex whereby a methyl methacrylate latex is formed first which acts as a substrate onto which the butadiene and styrene are grafted. In preparing the latex, the ratio of solids to water may vary over a wide range, but from an economic standpoint the ratio should be as high as possible, consistent with ease of handling and non-formation of fiocs. Typically latexes of the preferred embodiment of the present invention contain about 40% or more solids by weight.

The preferred emulsifying agent of the present invention is a combination of a fatty acid soap with an alkyl sulfate salt or an alkyl aryl sulfonate salt. In preparing a latex it is, of course, desirable to obtain as high a solids content as possible with as low a surfactant dosage as possible. However, for certain uses such as in the production of electrostatic sheets, binder plates, and like products, the amount of alkyl sulfate or alkyl aryl sulfonate required to obtain a high solids latex renders such latices unsuitable for their intended use. Thus quantities of sulfates and/or sulfonates substantially in excess of about 0.5 percent cause degradation of the latex electrical propy erties rendering the latex unsuitable for the production of electrostatic sheets and binder plates. Accordingly, fatty acid soaps have been employed in the production of polymers for this purpose since they do not adversely affect the latex electrical properties. Nevertheless, excessive quantities of such soaps are required to produce a latex of only about 35% solids. Attempts to increase the solids content by further increases in soap concentration have lead to coagulation due to the extremely small micelles formed. Attempts to utilize very low concentrations of sulfactants have resulted in low solids latices and indeed, in unstable latices which also were subject to coagulation dilficulties.

It has been discovered that very small amounts of alkyl sulfate salts or alkyl and sulfonate salts, when mixed with fatty acid soaps, provide a synergistic effect. The total quantity of surfactant required to obtain a stable methyl methacrylate-butadiene-styrenc latex is greatly reduced, yet, much h gher solids contents are obt i ed i the latex.

.T he alkyl group of the alkyl sulfate salt or the alkyl aryl sulfonate salt contains from 8 to 18 carbon atoms and preferably from 10 to 14 carbon atoms. The akyl sulfates or alkyl aryl sulfonates are used in the form of their salts such as an alkali metal or ammonium salt. The preferred salts are the potassium, sodium and ammonium salts. A mixture of alkyl sulfates may be used, such as is obtained from the sulfate salt of the alcohol mixture prepared by hydrogenating coconut oil. In addition, mixtures of alkyl aryl sulfonates, or mixtures of sulfates and sulfonates may be used.

Specific examples of alkyl sulfate salts useful as emulsifying agents in the present invention are sodium lauryl sulfate, sodium cetyl sulfate, potassium lauryl sulfate, ammonium lauryl sulfate and sodium octyl sulfate. Typical examples of alkyl aryl sulfonates useful in the present invention are sodium dodecyl benzene sulfonate, potassium dodecyl benzene sulfonate, sodium lauryl benzene sulfonate, potassium lauryl benzene sulfonate and ammonium dodecyl benzene sulfonate. The above examples are cited as illustrative and are in no way limiting.

The soaps used in combination with alkyl sulfate salts or alkyl aryl sulfonate salts are the water-soluble salts of the alkyl fatty acids having from 8 to 18 carbon atoms. It is preferred that the soap contain from 8 to 12 carbon atoms and most preferred are capric and lauric acid salts. The salts of the fatty acids constituting the soaps used in the instant invention are the alkali metal and ammonium salts of such fatty acids. The preferred salts for the purposes of the present invention are the potassium, sodium and ammonium salts. Mixtures of fatty acids may be used in preparing the soaps. In any event, the soap may be added as such or the free fatty acid and the desired alkali or mixture of alkalis added separately in the polymerization recipe to form the soap in situ. When forming the soap in situ, the alkalis should be present in an amount at least slightly in excess of the stoichiometric amount. Amine salts of alkyl sulfates, alkyl aryl sulfonates and alkyl fatty acid soaps have also been found to be very good emulsifiers when used in place of the alkali metal and ammonium salts. However, it has been found that alkanolamine salts, such as diethanolamine lauryl sulfate, deleteriously effect the electrostatic acceptance of the interpolymer films. Thus alkanolamine salts should be avoided when preparing latexes to be used as coating compositions in the preparation of electrostatic sheets and binde plates.

'In accordance with the present invention, polymerization mixtures are prepared which contain from about 0.5 to about 2.5 percent by weight of surfactant based on the total weight of monomers to be polymerized. The yield of latex solids, i.e., the methyl methacrylate-butadienestyrene interpolymer, is of course, generally less than 100 percent due to monomer losses, etc. Nevertheless, a low surfactant latex is produced in accordance with the present invention which contains no more than about 2.5 percent by weight of surfactant based on the weight of latex solids or resin. As used herein, the term weight of the surfactant is the sum of the weight of the acid from which the fatty acid soap is derived and the Weight of the sulfate salt, sulfonate salt, or sulfate-sulfonate salt mixture. Stable latices may be prepared in accordance with the invention in which the surfactant content is about 0.5 percent by weight based on the weight of latex solids or resin.

The weight ratio of acid to sulfate or sulfonate needed to obtain a stable latex will vary with the weight of the surfactant and, to a lesser extent, with the specific materials in the surfactant. The total quantity of sulfate and/ or sulfonate in the surfactant should not exceed about 0.5 per cent by weight based on the total weight of the monomers. larger quantities adversely affect the electrical properties of the latex and render it unsuitable for use in the production of polymeric coatings for electrostatic sheets and binder plates. In general, the amount of fatty soap should exceed the total amount of sulfate and/or sulfonate, although such is not absolutely essential in the very low ranges of surfactant. Nevertheless, the preferred and quite superior polymerization system, for the purposes of the present invention, is one in which the total surfactant is about 1 percent, and still more preferably, below 0.75 percent with the amount of fatty acid soap being substantially greater than the amount of sulfate and/ or sulfonate. Thus, the superior polymerization system includes surfactant in an amount in the range betwen about 1.0 to about 2.5 percent, and preferably, less than about 1.5 percent in which the surfactant consists of a major amount of the fatty acid soap and a minor amount of the sulfate and/or sulfonate salt.

Very minor amounts of the sulfonates and/or sulfates permit very great reductions in the amount of fatty acid soap required to obtain a stable latex of high solids content. Thus, quantities on the order of less than 0.5 are an effective amount of sulfate and/or sulfonate to permit preparation of a 50 percent solids latex in which the total surfactant content is on the order of about 1.5 weight percent.

In preparing binder plates, any of the conventional photoconductive pigments may be used with the aqueous latex. Such pigments include, without limitation, those set forth by Sugarman et al. in US. 2,862,815 and include, for example, the colored oxides, sulphides, selenides, tellurides and iodides of cadmium, mercury, antimony, bismuth, thallium, idium, molybdenum, aluminum, lead and zinc. In addition, arsenic trisulphide, cadmium arsenide, lead chromate and selenium may be used. Particularly preferred as the photoconductive pigment are zinc oxide, tetragonal lead monoxide, the sulfides and selenides of zinc and cadmium, and mixtures of zinc oxide and red mercuric sulfide. The pigment is first dispersed in water using a dispersing aid such as potassium tripolyphosphate. The pigment dispersion is then blended with the latex in the desired ratio, the solids content adjusted, and the coating mixture applied to the substrate using conventional coating equipment as an air knife, roller, dip blade, etc. If desired, a photographic sensitizing dye may also be added to the coating to improve the light sensitivity of the coating. The use of such dyes is set forth, for example, in US. 3,051,569 to Sugarman et al. and in US. 3,052,540 to Greig. The ratio of pigment to binder in the coating mixture is not critical. The ratios normally used in the art range from 1 to 8 parts of pigment to one part of binder. The precise ratio used will vary according to the end use and other considerations of the formulator. In general, a ratio of from about 1.5 to parts of pigment to one part of binder is preferred.

The economies possible by the use of the aqueous coating mixture of the invention are most clearly realized when the coating is applied to a paper web and accordingly this constitutes a preferred embodiment of the invention. However, the invention is not limited thereto and the coating composition may be applied to any type of substrate as is conventional in the art. It is preferred that the substrate be electrically conductive or semiconductive as for example, paper, metal, electricallyconductive plastic, or plastic or glass coated with an electrically conductive layer. If desired, the coating may also be applied to a completely insulating substrate in which case a special charging device must be utilized to supply an artificial ground plate as is necessary in xerographic processes. Such a device, termed a double corona, is described, for example, in US. 2,922,883. Where paper is used as the substrate, the paper itself may be first coated with a subbing layer or may be otherwise treated as by addition of hygroscopic salts, carbon black, metallic powders, etc., to impart a higher degree of electrical conductivity to the paper web. Wet strength resins, dyes and other additives normally added in the paper-making process may be used without detracting from the utility of the web to serve as the sub- EXAMPLE 1 A polymerization vessel was charged with the following ingredients:

Parts by weight Methyl methacrylate 50 Styrene 25 Butadiene 25 Capric acid 2.5 NH OH (28% aqueous sol.) 1.0 K S O 0.2 Sodium lauryl sulphate 0.1 Dodecyl mercaptan 0.012 Water 125.0

This mixture was polymerized at 65 C. for 18-24 hours while being agitated at a Pfaudler intensity of 2.0. The resultant latex was a floc free, fluid material having a Hamilton-Beach stability of at least 7 minutes.

EXAMPLE 2 A polymerization vessel was charged with the following ingredients:

Parts by weight Methyl methacrylate 50 Capric acid 2.5 NH OH (28% aqueous sol.) 1.0 K S O 0.2 Sodium lauryl sulphate 0.1 Water 125.0

This mixture was polymerized at 65 C. for 16-18 hours after which 25 parts by weight styrene and 25 parts per weight butadiene were added and the polymerization was continued for an additional 12 to 16 hours. As in example 1, polymerization was conducted under agitation at a Pfaudler intensity of 2.0. The latex thus prepared was a floc free fluid mixture having a Hamilton-Beach stability of at least 7 minutes.

Electrostatic sheets were prepared, using the latexes of Examples 1 and 2, by applying the latex to enamelcoated or bond paper, using conventional equipment and porcedures known in the art, as for example, a Warren Air Knife. The films were dried at C. to C. for two minutes and conditioned for 24 to 48 hours before testing. The same procedure may be followed for preparing binder plates, except. that a photoconductive material, i.e., zinc oxide, should be incorporated into the latex before application of the latex to the paper substrate. In the preferred embodiment of the present invention the coating weight of the nonpigmented electrostatic sheets is preferably within the range of 3 to 10 pounds dry weight per ream, however, good electrostatic properties are obtained with sheets coated with from 1.5 to 18 pounds dry weight per ream. The coating weight for zinc oxide pigmented binder plates is preferably within the range of 20 to 22 pounds dry weight per ream.

When coated on paper, the latexes of the present invention form a clear, non-yellowing, cohesive, non-blocking film. The films are found not to yellow even after exposure to an 8-1 sun lamp for 400 hours.

Paper sheets 4 in. by 6 in., coated with 8 to 10 pounds dry weight per ream of the latex of Example 1 were subjected on the coated side, to a negative voltage of 6500 TABLE I Percent V1 V2 retained relative humidity, 72 hours 1, 900 950 50 50% relative humidity, 72 hours 1, 500 850 57 75% relative humidity, 72 hours 1, 050 690 06 It was found that the electrostatic properties of coated sheets were not unduly effected by varying the film weight from 1.5 to 10 pounds per ream, and the relative humidity form 0 to 75% Paper sheets were coated with 2 to 18 pounds dry weight of the latex of Example 1, and subjected to a negative charge of 6500 volts at a relative humidity of about 47 to 53%. The charge accepted and the charge retained after 2 minutes were measured; the results are shown in graphic form in FIG. 2. A coating which accepts over 600 volts and retains over 50% of that charge for 2 minutes is considered to have excellent electrostatic properties. As is shown in FIG. 2 sheets coated with the latex of the present invention exhibit excellent charge acceptances and retention properties. It is also noted that while sheets coated with smaller amounts of the latex acceptance a smaller percentage of the charges than sheets coated with larger amounts of the latex, sheets coated with smaller amounts of the latex retain a higher percentage of the charge, thus permitting the use of smaller amounts of the coating than would be possible if the percentage of the charge retained was uniform for all coating weights.

Blocking was tested by coating paper sheets with the latexes of the present invention and forming films as herein described. Sheets 4 inches by 4 inches were placed with the coated side in contact with a glass plate, and a weight was placed on the glass plate so as to subject the sheet to 1 pound per square inch pressure. This assembly was placed in an oven and held at 70 C. for four hours, at the end of which time the assembly was removed from the oven and allowed to cool. If the sheets fell away from the glass plate without adhering thereto, no blocking was observed. Coatings made in accordance with the present invention exhibited substantially no blocking.

The binder plates and electrostatic sheets produced as herein described have excellent flexibility, tensile strength and bonding strength. Highly adherent coatings may be produced on a variety of substrates. :If desired, plasticizers may be added to the latex, but their use is not necessary. The binder plates and electrostatic sheets may be overcoated by a thin layer of protective resin, as known to those skilled in the art.

Prints were made on the electrostatic sheets of the present invention by imposing a voltage through a needle point onto the coated paper and developing the thus formed latent image in the usual manner as previously described. Prints were also made on the binder plates of the present invention in the usual manner by charging the paper in the dark, exposing it under white light and printing following the usual Electrofax process as previously described. In either case, clear, sharp prints were obtained of at least equal quality to those obtained using prior art electrostatic sheets and binder plates.

What is claimed:

1. A coating composition for use in preparing coated sheets comprising an aqueous latex, said latex having dispersed therein an interpolymer of methyl methacrylate, butadiene and styrene, the ratio by Weight of said methyl methacrylate to said butadiene to said styrene being selected so that the proportion of these monomers is represented by a point which falls within the shaded area of the ternary diagram of FIG. 1, and said latex further containing dissolved therein from about 0.5 to about 2.5 percent by Weight of a surfactant consisting essentially of a mixture of:

(A) an amount up to 0.5 percent by weight and effective to exert, with salt (B) specified hereinbelow, a synergistic dispersing effect, of a salt selected from the group consisting of the alkali metal and ammonium salts of alkyl sulfates, alkyl aryl sulfonates and mixtures thereof, the alkyl groups of said salts containing from 8 to 18 carbon atoms, and

(B) an effective amount, at least equal to the amount of salt (A) of a salt selected from the group consisting of the alkali metal and ammonium salts of fatty acids containing from 8 to 18 carbon atoms, the amount of said fatty acid salt exceeding the amount of salt (A) when the total surfactant is less than about 0.75 percent by weight,

the quantities of said surfactant and the components thereof being based on the Weight of interpolymer, with the amount of salt (B) calculated as the weight of fatty acid from which salt (B) is derived.

2. Process for emulsion polymerization of methyl methacrylate, butadiene and styrene, the ratio by weight of said methyl methacrylate to said butadiene to said styrene being selected so that the proportion of these monomers is represented by a point which falls within the shaded area of the ternary diagram of FIG. 1, comprising charging said monomers into a polymerization vessel, and polymerizing in a medium comprising water, said Water constituting no more than about 60 percent by weight of the polymerization mixture, and from about 0.5 to about 2.5 percent by weight based on monomer, of a surfactant, said surfactant consisting essentially of a mixture of:

(A) an amount up to 0.5 percent by weight and effective to exert, with component (B) specified hereinbelow, a synergistic dispersing effect; of a salt selected from the group consisting of the alkali metal and ammonium salts of alkyl sulfates, alkyl aryl sulfonates and mixtures thereof, the alkyl groups of said salts containing from 8 to 18 carbon atoms, and

the quantity of said surfactant being calculated as the sum of the weight of salt (A) and the weight of fatty acid from which salt (B) is derived whereby a stable, low

surfactant latex containing at least about 40 percent by atoms and fatty acid salt (B) contains from 8 to 12 car bon atoms.

'6. The coating composition of claim 1 in which said salt (A) is an alkyl sulfate salt.

7. The coating composition of claim 1 in which said salt (A) is an alkyl aryl sulfonate salt.

8. A process in accordance with claim 2 wherein the alkyl group of salt (A) contains from 10' to 14 carbon atoms and fatty acid salt (B) contains from 8 to 12 carbon atoms.

9. A process in accordance with claim 2 wherein said salt (A) is an alkyl sulfate salt.

9 10 10. A process in accordance with claim 2 wherein said 3,320,204 5/1967 Blanchard et a1. 260-80.7 salt (A) is an alkyl aryl sulfonate salt. 3,406,133 10/ 1968 Hartshorn 260--80.7

References Cited FOREIGN PATENTS UNITED STATES PATENTS 5 1,351,347 3/1963 France 260-80.7

2,744,099 5/1956 Mitchell et al. 26080.7 3,078,260 2/1963 Hayes DONALD ARNOLD, Prlmary Exammer 3,142,654 7/1964 Peterson et a1 26029.7T US Cl XR 3,176,037 3/1965 Warner 260-807 3,256,233 6/1966 Hahn 812211 260-29.7T 10 1