DE2012981A1 - Process for the surface treatment of thread-like material - Google Patents

Description

P.Λ ..? .. ^6. ^. ^r si b "

to the patent application

of the company

COtTRTAUIDS LIMITED
18, Hanover Square, London V. 1., England

concerning

Process for the treatment of threadlike surfaces

material

Priority dated March 19, 1969 No. 14434/69 Great Britain

The invention relates to surface treatment of thread-like material and in particular on machining the surface of filiform carbon to improve its properties sam incorporation in matrices eu.

Filamentous carbon, especially the one that is prepared by a process oaoh "is higher in the heat treatment at a temperature applied as 1.50O ⁰ O, tends to have a smooth surface which does not bond easily with a matrix. Its better binding capacity can be achieved by modifying the surface to a certain extent »The present

Invention relates to such an improved mode

009847/1714

. BATH ORIGINAL

fication procedure.

OβmaΒ of the invention consists of a method to treat the surface of filamentary or fibrous carbon in that an electrolyte in the form of an aqueous solution is elekfcrolyaiert, the filamentary carbon is connected to the anode, _{while the} nating oxygen flows into the surface of the surface -respectively. fibrous material is generated. A wKsarlse solution suitable for the process according to the invention contains hydroxyl ions and has a composition such that hydroxyl ions are formed at the anode during the electrolysis, which sucks in the passing oxygen. It is known that aqueous solutions which contain hydroxyl ions produce nascent oxygen during electrolysis, for example solutions which contain another anion, which is preferably released. Solvents such as these are not suitable for the method according to the invention.

Carbon filaments suitable for the purposes of the invention or fibers can be produced by using organic thread-like material, such as polyester, polyamide, cellulose or preferably polyaorylnitrilfädon or fibers different conditions in terms of temperature,

BATH ORIGiMAL

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Duration of treatment and ambient atmosphere. In general, for example, be characterized Rohlenstoffasern provides mountains "that a thread or organieoheo fassrfBrmiges material in air or another oxidizing · Qa is heated to about 200 ⁰ C and 300 bio carbonized product at a temperature above 1000 ⁰ C. The resulting carbonized filaments can be further heated to 150o ⁰ C and higher "to ersielen to" ine Graphitetruktur. Are carbonized threads ale at lower temperatures 150o C ⁰ "orden need uioht ootwendlgerweiee" ine surface treatment so e'e for incorporation into a matrix suitable to be. However, those which have been produced at a temperature above 1500 ^° C. generally require such a treatment.

Torzugoweise the electrolysis to be carried out according to the invention ir. carried out with an electrolyte, is an aqueous one Solution of an alkali hydroxide contains «Ee is forsaaieben, To use sodium hydroxide, dooh is any other alkali «' hydroxyd also ceeigoet. The concentration of the alkali hydroxide in the solution can vary within certain limits, dooh becomes from the standpoint of a quick reaction a solution preferably that is about 10 to 20 percent by weight Hydroxide contains

In the method according to the invention, the Kohlenetoffädeη

009847/175 * _ΒΑ0

2012931

All the anode of the electrolytic cell is switched while the cathode preferably a metal, like okel 1st, that together forms a cell with the Konlenstoffanode in which naazieren « the oxygen is generated on the surface of the threads. Bundles of staple fibers can be handled in an intermittent way by removing the whole Bundle attached to a suitable electrical contact will. It may be desirable that their freedom of movement constricted in the cell with the help of a ZeΙΐβαββparatore is · Continuous filaments are treated by being passed continuously through the electrolyte cell and then be removed. In such a case you can use the power source s.B. be connected by daa they run across a senior orphan who is youraeita with connected to the power source.

The inventive method is based on the following Examples are explained below.

Example It

Sin bunch aaa la essential Orasbitfaeern words In a knitted polypropylene cloth. bulk polypropylene cloth acted as a cell parator because there was frais circulation The slectrolyte loosang and the slectrolyte faithful tulleβ, but prevented dead loose fibers from creating a Knrseehlal in the slektro

BAD ORiGfNAL

009847/17 * 4

lytic cell elicited. The bundle was transformed into a proaeotige watery solution of sodium hydroxide immersed. Just" If so, a Hlokelelek was added to the sodium hydroxide solution trode immersed. A current of 2.5 A with a potential «, diffesens. of 6 volts was hindurobgeachiokt for 5 minutes, with the nickel as the cathode and the carbon fibers as Were connected to the anode. The fibers were removed from the line, the hess aia drained, ale rinsed and dried *

With the help of these treated fibers and an epoxy resin laminates were made. The interlaminar shear strength (a measure of the bond between resin urid fibers) was proven eich as outstanding compared to the laminates with lifting! " th fibers, * Untreated fibers gave a interlaminar shear strength of 190 kg / cm. Bln. Value * dem a laminate of 550 kg / cm, the fibers treated according to the invention have been produced

is. ■ · ■ "'- ■■' /" ,;

B sia pl e 1_ g .i

A continuous darn made of carbon fibers was made through sent a bath containing 15% sodium hydroxide solution contained. If it were used as an anode, it would blaze ο ran over a metal guide roller

_{/ BA} D

009847 / V764 "

Nickel plates were on the inner surface of the bede attached as cathodes. It was between the carbon yarn anode A potential difference of 6 volts is applied (via the Netall roller) and the nickel cathode. This potential difference resulted in a current of approximately 2.5 A below the conditions applied. The length of stay of the ea? Ns in the bath was 3 minutes. The treated yarn left the bath through nip rollers in order to remove the electrolyte to remove. Ea was then washed and dried and finally wound onto β in the take-up spool. This process is carried out with yarns made from high tensile strength carbon fibers and performed with high modulus carbon fiber yarns. Laminates made from the treated yarns had superior fiber / fiber bonding properties Compared to the untreated yarn. So was the interlatainam shear strength of laminates with fibers treated according to the invention with high strength 820 kg / cm and that of laminates with 3 loads according to the invention

J,

traded high modulus fibers 570 kg / cm. on the other hand had laminates made with untreated yarn from £ ohlen ~ fabric fibers had been produced, an “interlaminar shear strength of 190 kg / cm.

BATH ORIGINAL

0.9847 / 175;

Claims (2)

Pa ta _t η t «na ρ r U cha: H. Burning for treatment of the surface of thread-like carbon net off, thus knowing that an electrolyte in the form of a water-like solution is elactrolyzed, in which the carbon fibers move as an anode so that they contain acid, which means that the anode is attached to the acid developed ₍ 2. The method according to claim 1, characterized gekennseich η et that one uses βIe electrolyte a «hairy WJeuug of alkali hydroxide. 3 «Method according to Anapruch 1 or 2, characterized in that nan Koblenetoffaeero bsw.-ftdeo used in the form of continuous filaments, which are continuously sucked through and drawn through the electrolyte be removed again. BATH ORIGINAL 009847/17 54