US3808292A

US3808292A - Polyphosphonates

Info

Publication number: US3808292A
Application number: US00236203A
Authority: US
Inventors: H Petersen; F Fuchs; P Scharwaechter
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1971-03-26
Filing date: 1972-03-20
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: FR2130369B1; AT312554B; ZA722028B; CA989412A; BE781146A; GB1378962A; DE2114610A1; FR2130369A1; NL7204002A; IT952401B

Abstract

DERIVATIVES OF POLYHYDRIC ALCOHOLS CONTAINING IN THE MOLECULE, AT LEAST TWO PHOSPHONIC ACID GROUPS AND AT LEAST TWO CARBAMOYL GROUPS A PROCESS FOR THEIR MANUFACTURE AND THEIR USE IN FLAME-PROOFING CELLULOSIC TEXTILE MATERIALS.

Description

ii 3 a O a 23 Q V W. 1" I I i v United 1 3,808,292 POLYPHOSPHONATES Harro Petersen, Frankenthal, Friedrich Fuchs, Kirchheim,

and Peter Scharwaechter, Ludwigshafen, Germany, assignors to Badische Anilln- & Soda-Fnbrilr Alrtiengesellschaft, Ludwigshafen, Germany No Drawing. Filed Mar. 20, 1972, Ser. No. 236,203

Int. Cl. C07f 9/38,- D06c 27/00 U.S. Cl. 260-932 10 Claims ABSTRACT OF THE DISCLOSURE Derivatives of polyhydric alcohols containing, in the molecule, at least two phosphonic acid groups and at least two earbamoyl groups, a process for their manufacture and their use in flame-proofing cellulosic textile materials.

This invention relates to new derivatives of polyhydric alcohols containing, in the molecule, at least two phosphoric acid groups and at least two carbamoyl groups. The invention also relates to a process for the manufacture of said derivatives and to their use in flame-proofing cellulosic textile materials.

A large number of compounds has been proposed for the flame-proofing of cellulosic textile materials. For example, mixtures of boric acid or ammonium dihydrogen o-phosphate with borax have been used for treating textiles. However, this treatment has to be repeated after each wash.

Substances which are used to produce wash-proof finishcs are, for example, metal oxides which are precipitated onto the fibers. For example, there have been precipitated, in succession iron(III) oxide and a mixture of tungstic acid and tin(1 V) oxide or, in succession, antimony trioxide and titanium dioxide. However, such processes necessitate the use of a plurality of baths. Strong acid solutions and elaborate equipment are therefore very inconvenient. Moreover, a deposit of white metal oxide is formed on the surface of the textile material and this may lead to considerable difiiculties with certain colorations.

. Recent developments. involve the application of organic phosphorous compounds to the textile material: for example, cellulosic material has been treated with tetrakishydroxymethylphosphonium chloride in conjuction with an amino resin. However, when all components are used in a single bath, the amount of phosphonium salt and amino resin which must be absorbed toprovide adequate flame resistance is undesirably high and causes a weight increase of the treated textile material of from 20 to 25%. This large addition of material causes a considerable change in the handle of the textile material. Moreover, many textiles must be subjected to a special pretreatment in order to render them sufliciently adsorptive and absorptive to accommodate such a large amount of impregnating agent.

Another method proposed involved the use of tris-aziridin-l-ylphosphine oxide and tetrakis hydroxymethylphosphonium chloride. A serious disadvantage in the use of this combination is that aziridinyl-phosphorus compounds are highly toxic substances and their use is therefore extremely dangerous for the personnel involved.

Further proposals are made in German printed appli cations 1,469,281 and 1,594,974. In addition to these two references given as typical examples, there are many more patents, all of which, however, propose fundamentally similar compounds of phosphorus for use as flame-proofing agents.

They are compounds which are used alone or in con- 'atented Apr. 30, 1974 In these compounds, the substituent R" is always hydroen or alkyl or alkenyl having, preferably, from 4 to 6 carbon atoms.

These substances have brought indisputable advantages to the textile art under consideration.

Nevertheless, these compounds are not free from drawbacks. The methylol compounds of these dialkyl carbamoylalkanephosphonates are in equilibrium with formalclehyde. The free formaldehyde contained in the equilibrium mixtures leads to, odor nuisance; during treatment and also produces a fishy smell on the fabric when ammonium salt catalysts are used at the usual condensation temperatures of from to C. That portion of di'alkyl carbamoylalkanephosphonate in the equilibrium mixture which is non-methylolated cannot react with the cellulose fibers and thus constitutes a loss of flame-proofing agent. In general therefore, flame-proofing according to the teaching of the above references is carried out using dialkyl methylolor alkoxymethylcarbamoylalkanephosphonates in the presence of amino resin-forming substances.

However, combination with. such amino resin-forming substances stifiens the fabric undesirably and produces a hard handle. To counteract said hard handle, the above references propose the addition of plasticizers, but such an addition generally'weakens the flame-proofing effect.

A fabric treated in the above maimer meets all demands placed on a flame-proofed textile material, but it has been found that the tensile strength of a fabric thus treated is not always satisfactory, probably on account of the increased use of amino resin-forming substances. Fprthermore, it is often necessary to' re-treat the fabric after not more than 5 or 6 washes," since the wash-fastn'ess of these compounds does not permit a large number of washes. In order to be fully flame-proofed, the fabric must contain a minimum amount of flame-proofing agent. If the amount of said agent in the fabric drops by a only a few percent below the said permissible minimum, the

flame-proofing effect is lost extremely quickly and the fabric burns on ignition as though it had never been impregnated.

It is an object of the invention to provide compounds which act as flame-proofing agents on cellulosic textile materials and become bonded with the fibers sufficiently strongly without the use of said amino resin-forming substancesand which do not undesirably modify the handle and. tensile strengthof said fibers and which, above all,

in which R and R each individually denotes alkyl of from 1 to 4 carbon atoms or together form alkylene of from 2 to 3 carbon atoms, R denotes hydrogen or alkyl of from 1 to 4 carbon atoms and R can have the same or different meanings in any one molecule and denotes hydrogen, alkyl of from 1 to 3 carbon atoms, methylol, or alkoxymethyl of from 1 to 4 carbon atoms.

Of particular commercial significance are compound of Formula I in which A is the radical of a dihydric alcohol, n is thus 2 and B is a radical of Formula II in which R and R are identical alkyl radicals having 1 or 2 carbon atoms, R is hydrogen and R is hydrogen, methyl or methylol.

Of great importance commercially are compounds in which A is the radical of a dihydric alcohol of 2 or 3 carbon atoms, preferably of ethylene glycol or 1,2-propylene glycol.

As examples of particularly significant substances of the invention, the following compounds, represented by their respective formulae, may be mentioned:

CHaO O HO C20 O-CHr-NHC 0 CHaCHzi OCzHs CHsO CHO

o OCH! CHaO CH O

a OCH CHaO H:

O O CH:

CHz-NC OCHaCHaP Ha OCH:

CHaO

O OCH:

ll CHRHNC 0 CHzCHzP OCH:

CHaO O CH7CHgCON-CHz-OCHzCHzO- OHIO HQOH O OCH! ll/ CHz-N-COCHzCHzP HzOH OCH;

The process for the manufacture of the compounds of the invention is simple and is effected by the interaction of compounds of Formula III lLH 3 0 (III) with unsaturated acid amines of Formula IV:

H R H=CCO-I-IH with formaldehyde, and with compounds of Formula V:

.A.(H)n (V) in stoichiometric amounts, in any order, the symbols A, R R, R and R and n in Formulae III to V having the same meanings as given for Formulae I and II.

For example, a phosphorous acid dialkyl ester of Formula III may be reacted with an unsaturated acid amide of Formula IV, the resulting compound methylolated with formaldehyde and the product then reacted with one of said polyhydric alcohols of Formula V in stoichiometric proportions, i.e., in proportions such that all of the alcoholic groups take part in the reaction. However, the reverse route may be taken, for example, the unsaturated acid amide being methylolated with formaldehyde and the methylolated compound being directly etherified with the polyhydric alcohol and the resulting product then being reacted with the dialkyl phosphite.

In general, the reaction products of unsaturated acid amide, formaldehyde and polyhydric alcohol are already available. A representative of such compounds is for example the so-called glycolamol. Alternatively, the reaction product of the dialkyl phosphite with the methylolated unsaturated acid amide may be available and this can be reacted with the polyhydric alcohol.

Starting products for the manufacture of the products of the invention are dialkyl phosphites such as are described in German printed application 1,469,281. These are dialkyl phosphites of from 1 to 4 carbon atoms per alkyl radical. We prefer to use those in which the alkyl groups are identical and contain 1 or 2 carbon atoms, i.e., are methyl or ethyl groups.

It is also possible to use cyclic alkyl phosphites of 2 or 3 carbon atoms in the chain.

Other starting materials are the unsaturated acid amides. Suitable products of this kind are those substituted as defined above. Examplesthereof are acrylamide, methylacrylamide, ethylacrylamide, propyland butyl-acrylamides or their derivatives substituted at the nitrogen atom with C alkyl radicals or optionally etherified methylol radicals. The methylol radicals may be etherified, for example, with alkyl groups containing from 1 to 4 carbon atoms.

The preferred compounds are acrylamide, methacrylamide and N-methylolacrylamide.

The polyhydric alcohols which may be used as starting materials for the compounds of the invention and which form the main feature of the invention, are represented by alcohols of from 2 to not more than 6 hydroxyl groups in the molecule and containing from 2 to 6 carbon atoms. Suitable representatives are, for example, glycol, glycerol, propylene glycol, 1,2- and 1,3-butyl glycols, polyhydric alcohols bridged by oxygen atoms such as butyl diglycol and lower polyalkylene oxides having not more than 6 carbon atoms, pentitols, hexitols, sorbitol and spatially branched alcohols such as pentaerythritol. Preferred on a commercial scale are glycol and 1,2-propylene glycol, although very favorable results are also obtained using sorbitol or pentaerythritol.

Specifically, the compounds of the invention may be manufactured for example as follows: a glycolamol of the following formula:

in which A, R and R have the meanings given for Formula I, may be reacted with a dialkyl phosphite. This reaction proceeds readily in, for example, alkaline medium in the presence of, say, alcoholates or any other desired alkaline substance. Since this reaction is known in the art, it requires no further explanation in this description.

An alternative possibility, as outlined above, is to use one of the polyhydric alcohols to etherify a compound of the formula:

prepared in known manner by reacting dialkyl phosphite with one of said unsaturated acid amides, e.g. acrylamide, followed by methylolation with formaldehyde. The etherification proceeds in known manner in the presence of acid catalysts such as sulfuric acid, boron fluoride etherate and other Lewis acids. If desired, the compounds may be further methylolated at the nitrogen atoms and these methylolated compounds further etherified with one of the usual etherifying agents.

In all cases, the materials of Formula I of the invention are obtained in excellent yield and purity.

The materials of Formula I may be used with great success as flame-proofing agents for textile materials, particularly those consisting of or containing natural or regenerated cellulose. Particularly suitable textile materials, to which the materials of the invention may be applied, are for example cotton and regenerated cellulose.

Fabrics finished with the materials of the invention are distinguished by a very soft handle, excellent wash fastness and the complete absence of odorous substances.

Their use as flame-proofing agents may take for example the following form: the textile material to be treated is impregnated with one or more materials of Formula I and is then reacted therewith in the presence of at least one acidic and/or potentially acidic catalyst. It is preferred to use the materials of Formula I in the form of aqueous baths. The concentration of materials of Formula I in said baths is generally between 200 and 600 g./l.

The applicationof said substances is carried out using apparatus commonly employed for aqueous systems in the textile industry. It is preferred to make use of a padding machine forimpregnation. The impregnated material is thus freed from excess liquor by squeezing in known manner.

The impregnated textile material may, for example, be dried and then heated to a temperature of up to 200 C. and preferably of from 130 to 170 C. in the presence of acidic or potentially acidic catalysts. Under these conditions the reaction is generally complete in from 1 to 6 minutes.

Acidic or potentially acidic catalysts for use in this type of treatment are Well known. Suitable compounds are, for example, inorganic or organic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, oxalic acid and their acid-reacting salts or compounds capable of forming acids during use, for example due to the action of heat and/or hydrolysis, for example ammonium or amine salts, and also Lewis acids such as magnesium chloride, zinc chloride and zinc nitrate. Particularly good flame-proofing effects are achieved when using monoor di-ammonium phosphates. As mentioned above, the reaction of the materials of Formula I is carried out in the presence of such catalysts. This may be effected by applying the catalysts, preferably in the form of aqueous solutions, to the textile material immediately after it has been impregnated with the novel substances. Preferably, however, the catalysts are added directly to the bath con taining the materials of Formula I. Catalyst concentra tions in said baths of from 1 to 40 g./l. have been found to be convenient.

Fabrics which have been rendered flame-proof in this manner are distinguished by excellent properties in respect of handle, tensile strength and flame resistance. It is possible to add to the baths, in addition to the mate rials of Formula I, other finishing agents such as nitrogen-free hydroxylmethyl or alkoxymethyl compounds, polyethylene glycol formals andcompounds containing epoxy groups such as glycol diglycidyl ether. Finally, amino resin-forming materials may also be used without the addition of plasticizers being essential, as hitherto necessary with prior art flame-proofing agents. In addition, conventional water-repellent, softening, leveling, wetting and finishing agents may be used if desired. Examples of suitable water-repellent finishes are aluminum-containing or zirconium-containing paraffin wax emulsions, siliconcontaining compositions and perfluorinated aliphatic compounds. Typical softeners are, for example, ethoxylation products of high molecular weight fatty acids. fatty alcohols or fatty acid amides; high molecular weight polyglycol ethers and esters thereof; high molecular Weight fatty acids; fatty alcohol sulfonates, stearyl-N,N-ethylene urea; and stearylamidomethylpyridinium chloride. Suitable leveling agents are water-soluble salts of acid esters of polybasic acids with ethylene oxide adducts or propylene oxide adducts of longer chain alkoxylated substances. Examples of wetting agents are salts of alkyl naphthalene sulfonic acid, the alkali metal salts of sulfonated dioctyl succinate and addition products of alkylene oxides with fatty alcohols, all-:yl phenols, fatty amines. etc.

Suitable finishing agents are cellulose ethers, cellulose esters and alginates, and also solutions or dispersions of synthetic polymers such as polyethylene, polyamides, eth oxylated polyamides, polyvinyl ethers, polyvinyl alcohols, polyacrylic acid or its esters or amides or correspond polymethacrylic compounds, polyvinyl propionate, polyvinyl pyrrolidone, copolymers such as those of acrylates ormethacrylates with at least 20% by weight of acrylic and/or methacrylic acid, those of vinyl chloride and acrylates, of butadiene and styrene or acrylonitriles or those of a, 3-dichloroethylene,fi-chloroalkylacrylates or vinyl B-ethyl ethers and acrylic acid amide or the amides of crotonic acid or maleic' acid or those of N= methylol methacrylamide and other polymerizable compounds.

After reacting with the materials of Formula I and, where applicable, with any of the aforementioned additives, the textile material possesses excellent flame-proof properties which are very fast to hydrolysis and washing and which are accompanied by complete absence of odor. The flame-proofing properties are always realized whether or not the aforementioned additives are used. Only specific uses of the fabric can justify the inclusion of said addi tives, although this does not in any way influence the re sults obtained by the present invention.

Particular advantages of our novel compounds in the said field of application are that flame-proofing may be carried out using a much smaller quantity of flame-proofing agent than hitherto necessary and that the amount of said acid catalysts required is thus also much less.

These advantages are accompanied by a much shorter reaction time, and the resulting combination of advantages ensures most gentle treatment of the fabric.

In the following examples the parts and percentages are by weight unless otherwise stated. Parts by weight relate to parts by volume as do kilograms to liters.

To a mixture of 1,320 parts of dimethyl phosphite and 1,368 parts of glycolamol there are added, with stirring at from 70 to 80 C., 150 parts of a 30% sodium methoxide solution. The addition reaction begins after about 50 parts of the sodium methoxide solution have been added. The temperature may be regulated by using a cooling bath The reaction mixture is heated at 70 C. for 40 minutes and then cooled to room temperature with crystallization of the product. There are obtained 2,500 parts of product, this being equivalent to a yield of 93% of theory. The product is recrystallized from acetone/methanol and then has a melting point of from 126 to 128 C. Its formula is as follows:

HaC O\$]) P-CHzCHzC ONHCHzO CHzCHzO CHzHNC O CHrCHr- H500 O OOH:

OCHs

Its molecular weight is 448. Analysis results are as follows:

Found (percent): C, 37.5; H, 6.9; N, 5.8; O, P, 13.7. C H O P requires (percent): C, 37.5; H, 6.7; N, 6.2; 0, 37.7; P, 13.82.

EXAMPLE 2 A mixture of 724 parts of dimethyl Z-carbamoylethane phosphate, 300 parts of 40% formaldehyde solution and 60 parts of 25% caustic soda solution is stirred for 2 hours at 50 C. The reaction mixture is then reduced to about 870 parts by evaporation under reduced pressure. To the sirupy residue there are added 124 parts of ethylene glycol and 20 parts of phthalic acid, and the mixture is heated at 50 C. for 3 hours. The mixture is neutralized with caustic soda solution and cooled to room temperature. The reaction product crystallizes after standing for 1 day. The yield of crude product is 790 g., equivalent to 88% of theory. The crude product may be recrystallized from a mixture of acetone and methanol. The results of paper chromatography and the mixed melting point show that the product is identical to that produced in Example 1.

EXAMPLE 3 C H; CH5

0 OCH:

OCH:

905 parts of dimethyl carbamoylethane phosphonate (5 moles), 375 parts of 40% formaldehyde solution and parts of a 10% caustic soda solution are heated in a stirred vessel for 3 hours at 50 C. 160 parts of water are evaporated off under reduced pressure, and 190 parts of propylene glycol-1,2 and 14 parts of 45% sulfuric acid are added. The reaction mixture is heated at 60 C. for 4 hours. The water formed during the reaction is then distilled off under reduced pressure. Tne mixture is then neutralizer with dilute caustic soda solution at room temperature. The reaction product crystallizes on standing for 1 day. There are obtained 900 parts of product, equivalent to 78% of theory.

EXAMPLE 4 crno P-CH CHzCONH-CHz-O(CH,) O-CH one CHI:

bamoylethane phosphonate, 225 parts of butanediol-1,4 and 25 parts of phthalic acid is heated for 3 hours at from 60 to 65 C. in a stirred vessel. The mixture is neutralized with caustic soda and the reaction product crystallizes on standing for a short period at room temperature. There are obtained 860 parts, equivalent to 72% of theory.

EXAMPLE 5 25 parts of a 30% methanolic soduim methoxide solu tion are added dropwise to a mixture of 228 parts of glycolamol and 276 parts of diethyl phosphite with stir ring at from to C. The reaction is controlled at 85 C. by cooling. The mixture is then heated at 80 C. for a further hour. There are obtained 475 parts of prod uct, equivalent to 94% of theory. Its formula is as follows:

--CH2CH2C ONHCHrO CHzCHnO CHQNHC O CHzCHr- H5030 O OCzHs ii/ OCzI-I Its molecular weight is 504. The results of analysis are as follows:

Found (percent): C, 42.4; H, 7.2; N, 5.15. 5C 5 6H N O P requires (percent): C, 42.8; H, 7.5; N,

EXAMPLE 6 300 parts of the compound of the following formula:

CH: 0 O

PCHaCH: C ONH-CHz-OCHaCI-I: O---- CH; O

O OCHB g/ CHn-HN C OCHzCHI OCH;

and 15 parts of monoammonium phosphate are made up to 1 liter with water. Cotton twill weighing 170 g./m. is padded with this solution at room temperature to give a Wet pick-up of The treated cotton is then dried at 100 C. The dry fabric is subjected to heating at C. for 5 minutes. The material is stored for 24 hours under standard conditions and the weight of flame-proofing agent on the fabric is found to be 21% of the dry weight of the fabric. The fabric is then treated for 2 minutes with a 0.2% aqueous soda solution at 70 C. After rinsing and acidifying with dilute acetic acid followed by thorough rinsing, the fabric is dried. The cotton fabric thus treated is flame-proof.

Tests carried out according to German Standard DIN 53,906 give the following results:

Fabric after machine 1 Commercial domestic detergent such as that sold under the name 01' Dixon by Procter & Gamble (Dhran" is 0. registered trademark).

It Burnt through.

EXAMPLE 7 EXAMPLE 9 A piece of cotton twill weighing 170 g./m. is added 320 parts of the compound of the formula: with an aqueous bath containing 325 parts of the follow Omo 0 mg -on,orr,oorzn-oH|-oomomo onron 0 on,o I 0 con.

P-CHrCI-I C ONi-CHs- -OCHgCHsO EN 0 0 Q HICHH 11 omo H.011 0cm 0 com i are dissolved in about 500 parts of water. 20 parts of C r-HNQ0CHlCHl* 85% phosphoric acid are then added and the solution is stirred well and made up to 1 liter with water. A piece and 17 parts of monoammonium phosphate per liter of solution, so that a wet pick-up of abo'ut90% is achieved. The fabric is dried at 110 C. and treated onatenter for 5 minutes at 165 C. After storage under standard conditions for 24 hours, the rate of application is found to be 22% of the dry weight of the textile material. The fabric is then washed with a 0.2% soda solution for 2 minutes at 70 C. The fabric is rinsed until neutral and then redried.

The fabric thus treated is ilame-proof according to German Standard DIN $3,906.

Fabric after machine Fabric bollln at. 06 (Losing alter 1.5 g. oi Dixan tor- 350 parts of the compound having the formula CHO o P-omcmooN-on, oorr,or1,o-

CH1 0 HIOH and 18 parts of monoammonium phosphate are dissolved in water and made up to 1 liter of solution. A piece of cotton poplin which has been well washed after dyeing and is absorptive, is padded at room temperature with this solution to give a wet pick-up of- 80%. The weight of the poplin is 350 g./m. The material is dried at 100 C.

OCH: 4

and then heat-set on a tenter for 5 minutes at 165 C.

After storage under standard conditions for 24 hours, the rate of application is found to be 23% of the dry Weight of the textile material. The fabric is treated with'a 0.2% aqueous soda solution for 2 minutes at 70 C. in-a washing machine and then rinsed until neutral arid'finally dried.

Tests carried out according to DIN 53,906 give the following results:

l B urnt through.

of cotton twill weig ['ng 170 gJm. is padded with this solution to give a et pick-up of The fabric is then dried at 100 Ci The dry fabric is heated for 4 minutes at C. After'stori g for 24 hours under standard conditions, the rate of appl cation of flame-proofing agent is found to be 22% (if the, dry weight of the textile material. The fabric is then treated with a 0.4% aqueous soda solution for 2 minutes at 70 C. The fabric is rinsed until neutral and then redried. After storage under standard conditions, the following results are obtained when testing according to and $3,906:

in which A is the radical of an n-hydric aliphatic alcohol with 2 to 6 carbon atoms, n is a whole number from 2 to 6 and in which R and R denote alkyl of from 1 to 4 carbon atoms or together form an alkylene radical of 2 to 3 carbon atoms, denotes hydrogen or alkyl of from 1 to 4 carbon atoms; and R denotes the same or different radicals selected from hydrogen atoms, alkyl of from 1 to 3 carbon atoms, methylol or alkoxymethyl of from 1 to 4 carbon atoms.

2. A compound its set forth in claim 1 in which A is the radical of a dihydric alcohol, I: is the integer 2 and in which R and R are identical alkyl radicals of'l or 2 carbon atoms, R is hydrogen or methyl and R is hydrogen, methyl or methylol. .j

3. A compound of the formula:

4. A compound ofthe formula:

r sO CHgCHs-O-CHr-HNC OCHgCHr- OCsH l 6. A compound of the formula:

CHaO 0 -cH1cm00NH-oH10-0H- CHaO H:

cm-o-cm-mzo 0CH:CH7-P 00H 7. A compound of the formula:

CHaO 0 -0H=CH,C ONCHa0- CHaO HI H; OCH! 8. A compound of the formula:

CHaO O r -CH:CH1C ONE-CH:-

CHxO

(R/OCH; O(CH1) O-CHr-HNCOCH:CH-P

15 CHIO 12 f 9. A compound of the formula:

CHaO HgOH OCH;

1W. A compound of the formula:

0 Lomcmcow-cnrcmo mos O OCH; ocmcmo-cm-N-oocmom- H|OE OCH;

Refereuce's Cited UNITED STATES PATENTS 3,579,532 5/1971 Nachbur et a1. 260-932 x 3,658,952 4/ 1972 Nachbur ct a1. 260 -932 ANTON H. SUTIO, Primary Examiner US. Cl. X.R.

8-l16 P; 106-15 FP; 117-437; 260-943 UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,808,292

DATED April 30, 1974 INVENTOR(S) Harro Petersen, F. Fuchs, and P. Scharwaechter It is cerrrr'rerj that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, insert-Claims priority, Application German, March 26, 1971, P 21 14 6l0.l-;

Column 7, line 25, delete "C H O P and insert Column 7, line 61, delete "Tne" and insert--The-;

Column 7, line 69, delete "CH O" and insertCH O-;

Column 7, line 71, delete "CH and insert-OCH Signed and Scaledthis eleventh D a-y Of November 1 9 75 [SEAL] A nest:

R'UTH C. MASON C. MARSHALL DANN X ff?? (nmmissr'mrcr nflure'ms and Trademarks