JPH01500133A - Electrochemical surface treatment method for carbon - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A method for electrochemical surface treatment of carbon, carbon treated by the method, especially carbon fibers, and composite materials containing such fibers The present invention relates to an electrochemical surface treatment method for carbon materials.The present invention relates to a method for electrochemical surface treatment of carbon materials. for resin in a composite material consisting of carbon fibers embedded in a matrix of It is particularly applied to the surface treatment of carbon fibers for the purpose of improving the adhesion of the fibers.

Background of the invention The mechanical properties of carbon-resin composite materials are on), which is improved by increasing the shear stress when carbon fibers and This means that the adhesion between resins has been improved. However, excessively strong adhesion This will make the material more fragile. That is, the toughness decreases.

As-produced carbon fibers are treated by chemical or other electrochemical means. It has already been proposed that surface treatment can improve the adhesion of fibers to resin. It is being proposed. Chemical groups are added to the fibers in this way to improve the adhesion of the fibers to the resin. In this case, the improvement in adhesion is to a considerable extent due to the interaction between the fibers and the matrix. However, at the same time, to some extent The degree of van der Waals interaction between fiber and resin components, i.e. bipolar This is done by increasing bipolar interactions.

This type of electrochemical treatment is described, for example, in French patent application 2.477.593 It is explained in the issue. This essentially involves soaking the fibers in an electrolytic solution and attaching the fibers to the cathode. It consists of giving positive polarity to the opposite. Good adhesion, especially for residual salt Using ammonium and sodium sulfate and bisulfate electrolytes It is obtained by

These electrolytes contain oxygenated anions, which transfer oxygenic groups onto the carbon fibers. These oxygenic groups cause the fibers to react to synthetic resins (raft). Although improving adhesion, this treatment method sometimes degrades the mechanical properties of carbon fibers. Sometimes.

The earlier application mentioned above uses strong bases as electrolytes (sulfuric acid, phosphoric acid, sodium hydride). It also describes the use of a strong acid and a strong acid. In addition, the impregnated fibers are stiff ( It is said that the thermal oxidation resistance of the treated fibers is reduced. It's being ignored.

When examining the operating conditions of conventional electrochemical processes, they generally An anode made of carbon fiber and a cathode are separated using an acid, base or salt solution. The electric potential applied between the This indicates that it is large enough to generate oxygen.

The electrolyte then forms oxygenated surface groups that promote fiber-matrix adhesion. It contains reactive specles that attack the carbon of the fibers.

When water decomposes and oxygen is generated, the potential v0 is saturated monochlorinated water 11 (satu-r It is approximately +1.7 volts with respect to the reference electrode of may be smaller for electrolytes that contain In any case, it will be done beyond V. Regardless of the electrolyte used, anode treatment always involves the splitting of water and oxygenated groups (C-0 , COH, C0OH, ... type) and the working voltage. The position Vt is ■. If the proportion of oxygen groups is much larger than that, it will cause deterioration of the fiber surface. Only the concentration and surface concentration differed between the methods. and provided by oxygenic groups The fiber-matrix interface is essentially the same regardless of processing method. Because of the nature of this, we can hardly expect any improvement in the toughness of the resulting composite material.

In the applicant's published French patent application no. 2.564.489, nitrogenous There is a method of surface-treating carbon fibers for the purpose of grafting carbon fibers onto carbon fibers. It has been stated.

In this method, the fibers are ■. To avoid dropping too much water, remove most of the water. Immersed in an aqueous solution of an amine compound that does not let go.

The purpose of the present invention is to overcome the limitations associated with the use of aqueous solutions, in particular with respect to the rate of electrochemical reactions. Electrical techniques that graft nitrogenous groups onto the surface of carbon fibers The purpose is to provide a chemical method.

Another object of the invention is that carbon fibers in other forms than carbon fibers, in particular used as catalysts, e.g. The purpose of this is to graft a nitrogenous group onto a split form of carbon.

Summary of the invention The present invention involves contacting carbon with a solution of an amine compound in a dipolar solvent to form a cathode. 1. A method for electrochemical surface treatment of carbon, wherein said solvent is highly Has an anode oxidation potential and the solution is substantially free of water. .

The solvent is preferably an aprotic dipolar solvent.

In order for a nitrogenous substance to be grafted onto the carbon surface by electrochemical means, three conditions must be met. conditions must be met.

The first condition is that the surface reactivity of carbon must be sufficiently high; This means microporous carbon, carbon that can be graphitized at low temperatures, and This applies to surface activated carbon.

Carbon is broadly classified into graphitizable carbon and non-graphitizable carbon.

Microporous carbon has a turbo-stratic structure. It is a graphitizable carbon with low La5LC in X-ray diffraction and high analytical accuracy. The micropore structure of microstructures observed using a submicroscope and the micropore structure observed using an optical microscope. It is characterized by an isodirectional structure when observed.

La and Lc indicate the dimensions of the basic tissue unit parallel and perpendicular to the aromatic layer, respectively.

The unit of micropore is about several ten times nanometer, and La is , the twist of the layer cannot be reduced and therefore remains small regardless of the heat treatment temperature.

The so-called [high strength J and "intermediate strength" carbon fiber, carbon black, Pyrocarbon, which consists of ing.

"High strength" carbon fibers have two or three small dimensions (approximately lO angstroms) A basic organizational unit formed by the terposdratic stacking of aromatic layers. It has a microstructure composed of a collection of UTBs. UTB is sp″ type that forms a joint by non-directional bending and twisting. connected to each other by chemical bonds. “High-strength” fibers mean that the average direction of the fibers is It consists of a set of UTBs in the axial direction. The surface of such fibers is electrified It has a dense sp3 type packing suitable for being attacked by chemical means.

"Intermediate fibers" have a UTB that is slightly larger than the dimensions of the "high strength" fibers. However, although the surface concentration of sp type 2 bonds is not very high, the degree of formation remains high. There is.

“High modulus J fiber carbon is a high La non-carbon material. Similar to graphitizable pyrocarbon, but it maintains a microporous state . This type of carbon is not suitable for treatment according to the invention unless it has been previously activated. isn't it.

``High modulus'' fibers are treated with ``graphitization'' between 2000°C and 3000°C. Because they are different in size, they have UTBs of very different dimensions. UTB is 1000 oz. 10 tarposdratic layers of aromatic layers that reach or exceed Strom. It's a great accumulation. As a result, the density between UTB connections is lower than that of "high strength" fibers. The bonds between carbon atoms belonging to the aromatic cycle are therefore very stable. properties, giving "high modulus" fibers very low surface reactivity.

The action of nitrogen plasma on the surface of such fibers removes carbon atoms from the aromatic layer on the surface. , thereby increasing its reactivity by expelling the enable.

Graphitizable carbon is characterized by Lc being greater than La below about 1500°C. However, its La increases when the temperature exceeds 1500℃, especially when the temperature exceeds about 2000℃. (as observed using high-resolution electron microscopy grating fringes) It becomes a periodic structure (graphitization).

When the processing temperature is between 600°C and 1000°C, La and Lc are equivalent (-2, 5 nm), and then Lc increases up to about 1500°C. Above this temperature , La increases and becomes larger than Lc.

Carbon, which can be graphitized at low temperatures (0.51500°C), is susceptible to electrochemical processing reactions. It has a sensitive microstructure. Can be graphitized at high temperatures Carbon becomes sensitive only if the surface is previously activated.

The second condition that allows grafting to occur is that the operating potential Vt is such that the solvent Or, the decomposition potential of the pair of solvent + auxiliary electrolyte must be less than VSOL. be.

The organic solvents used for the treatment include acetonitrile, dimethylformamide, etc. or dimethyl sulfoxide. A supporting electric current is added to the solvent. It is preferable to add an electrolyte, the auxiliary electrolyte having a high anodic oxidation potential VtS. It should depend on the nature of the organic solvent. Suitable auxiliary electrolytes include: Lithium perchlorate, 4-ethyl perchlorate Tetraethylammonium perchlora te) or, for example, tetrafluoroborate ), alkaline or quaternary ammonium tetrafluorophosphate (quatern ary　aa++5onius+tetrafluorophosphate) is included.

Generally, the working potential VL is controlled by the oxidation potential of the auxiliary electrolyte and the solvent used. , and thereby the potential of the given pair 3°L is determined. Listed below The table below observes the vsoL changes for various solvents and auxiliary electrolytes.

Solvent: Auxiliary electrolyte: Saturated calomel 0. ■3゜L for OIM! against the pole Ru ■,. L Acetonitrile ClO4-+ 2.6V + 2.3VBF4-, PF6- + 3.5V + 3.2V acetic acid CH*COO-+ 2V + 1.7V 0 0 Meta 7 Cl0n + 1.9V + 1.6V Finally, the third condition is the operating voltage The oxidation-reduction potential Vt of the amine compound must be greater than the oxidation-reduction potential Vt of the amine compound. Yes, and if the amine compound contains some amine functions, the Vt will be the minimum It must be greater than the oxidation-reduction potential. Electrochemical reaction is rapid For this to occur, the difference between Vt-V is large (and Vt<Vs).

Furthermore, it is preferable not to bring Vt too close to v3°. , the reason is that then the oxidation products of the amine accumulate, forming a thin film on the electrode. and remains on the surface, like the passive lion of the anode. This is because interference electrochemical phenomena may occur. us) The use of electrolyte solutions makes it easier to relax the last two conditions and reduces the As a result, it allows for faster processing than would be possible using an aqueous solution.

The amine compound used in the treatment is preferably ethylenediamine, Oxidation-reduction potential V in sliver carbon! is acetonitrile and 0.1M perperchloric acid For a tetra-type electrode, V, = +0.9 volts).

Other suitable compounds include amines with low oxidation-reduction potentials such as 6-methyl-2-pyridine. There are other compounds that also have

The treatment is carried out at a potential too low for the solvent and auxiliary electrolyte to decompose. good Good results were obtained with an actuation voltage of approximately 1.3v relative to a reference electrode of 0.0IM Ag/Ag'''. This value is obtained by polarizing the fiber to give a value Vt of ■ Pair of nitrile and lithium perchlorate. , the value is much lower than this electrode It is approximately +2.3v.

Vt -1.3V is the resistance range of the polarization curve. It is located at the beginning.

The present invention, in particular in fiber form, is processed by the method described above with composite materials. The carbon treated in accordance with the present invention may be split or powdered to provide carbon. The supplied carbon also belongs to the category of microporous carbon and is graphitized carbon at low temperature. , carbon with an active surface.

Brief description of the drawing Embodiments of the invention are described by way of example with reference to the accompanying figures, in which: FIG. 1 is a schematic diagram of an experimental apparatus for carrying out the method of the present invention; Figure 2 shows a characteristic curve showing the change in current as a function of the potential applied to the fiber; Figure 3 is a diagram of industrial equipment for carrying out the method using carbon fibers; FIG. 4 is a diagram of an industrial apparatus for carrying out the method using split carbon; Figure 5 is a diagram of an experimental setup for treating carbon fibers with nitrogen plasma; FIG. 6 shows an aqueous medium that was initially untreated but was subsequently treated with an aqueous medium. C0URTAU treated with hexamethylene tetramine in LDSi! Regarding Grafil IT, photoelectron spectroscopy technology (i.e. ESCA Jelectron Spectroscopy for Che+m1cal A analysis) and secondary ion mass spectrometry techniques (i.e. SIMS = Seco Obtained using ndary Ion Mass Spectrometry) Figure 7 is a set of spectra for fibers treated with hexamethylenetetraamine. Figure 8 shows the details of the electrophotographic peaks obtained for fibers in an aqueous medium. of C0URTAULDS after treatment with amine 6 methyl 2 pyridine in Separation of ESCA and S1MS spectra obtained for Grafil HT woven fibers showing the cut; Figure 9 shows C0URTAULDS (7) after treatment with urea in aqueous medium. ) ESCA and S1MS spectra obtained from Grafil HT fiber set, Figure 10 shows ethylenediamine in acetonitrile with lithium perchlorate added. C0URTAULDS Grafil HT woven fibers after treatment with A set of ESCA and 31MS spectra obtained by Figure 11 after treatment with amino 6 methyl 2 pyridine without auxiliary electrolyte. ESCA obtained for the same fiber of,! ! :S IMS set, Figure 12 is Ethylenediamine in dimethylformamide with the addition of lithium perchlorate. C0URTAULDS Grafil HT woven fibers after A set of ESCA and SIMS obtained by Figure 13 shows the distribution of fiber-matrix in the three types of aqueous media mentioned above. This shows the change in release stress τ4 as a function of duration, and the resin used was Aral. The curing agent is HT972, and both are CIBAGEI. Made by GY.

Figure 14 shows the use of ethylenediamine in acetonitrile with lithium perchlorate added. The resin used is CIB. A GEIGY Araldite LY 556 and NARMCO520B ), Figure 15 shows epichlorohydrin treated with hexamethylenetetraamine. Indicates that it will stick to fibers but not to fibers that have not been treated as such. This is a set of ESCA spectra for

more detailed explanation In the experimental apparatus schematically shown in Figure 1, an anode is formed in the tank 1 and an insulated A bundle of carbon fiber monofilament 3 surrounded by supports 4 is submerged. Contains electrolyte solution 2. The anode includes a platinum cathode 5 and a reference electrode 6. The potential is maintained at a set voltage between the anode and the reference electrode by being immersed in the solution 2. It is connected to a potentiostat 7 to The set voltage is Avoid the release of oxygen by electrolysis or use a non-aqueous medium (nonaqueous medium). Consists of auxiliary electrolyte (Li C104) in eous a + edium) and solvent chosen to avoid decomposition of the mixture. The reference electrode 6 is treated in an aqueous medium. saturated calomel electrode for or in acetonitrile for processing in non-aqueous media 0. OIM Ag/Ag” system.

Argon is blown into the bath via a tube 8 that opens below the fibers 3. child This prevents oxygen from entering the bath.

Electrolytic bath 2 is either an aqueous solution of an amine compound or an amine compound and an auxiliary voltage in a dipolar solvent. It is either a solution of solutes.

An electrochemical reaction occurs at the solution-fiber interface, where nitrogen is It has the effect of grafting groups or molecules of amine compounds onto the surface of the fibers.

The curve in Figure 2 shows the variation of the current I through the anode as a function of the potential ■ with respect to the reference electrode. It shows that When the potential is sufficiently small, a current of value I0, which is almost unrelated to the potential, can get. At high voltages, the current increases rapidly and passes through a curved section, characteristic of a resistive state. It connects to the straight line part that shows the gender.

The operating potential Vt is as high as possible, but the acid in the aqueous medium (Examples 1.2 and 3) ■ The value at which the element begins to occur. or below the resistance range of the non-aqueous medium (Example 4). It will be done. In Examples 1 to 3, ■. so that the compound does not dissociate too much in water, -C, about 1.7 volts (for a saturated calomel electrode), and the working potential is 1.5 The zero operating potential Vt (which can be chosen close to volts) in a non-aqueous medium (Example 4) (approx. Close to the beginning of Vt, it slows down the electrochemical process. There is no advantage to choosing a value.

The organic solvent (e.g. acetonitrile) must not contain any water, if any If it is, it must first be dehydrated; the other characteristic is that it is the electrical Unless it is involved in a chemical process, i.e. its decomposition potential is higher than the operating potential Vt. It must be bipolar to dissolve auxiliary electrolytes, the nature of which is unimportant, as long as the It is a must. Additionally, if the solvent is aprotic, it is The choice of dipolar solvents, which aid in stripping protons from on-groups, is such that the decomposition potential is lower than Vt. This is done considering only that it is large enough.

The curves in Figure 2 generally do not show the oxidation-reduction peaks of amine compounds; The reason is that the arrangement of electric field lines is This is because the area near the filament electrode is complicated. The potential Vt is at the time of this explanatory text. points were determined for only a few of the amine compounds, but still Depends on solvent and auxiliary electrolytes.

The potential VT is acetonitrile ten perchlorate tetraethylammonium +Ag/A Confirmed that +0.9 volts for ethylenediamine at the g’ electrode , which is smaller than the operating potential of Example 4 (Vt-1.3 volts), thus , Vz<Vt<Vs. , the conditions are completely satisfied.

An apparatus for continuously processing fibers is shown in FIG. From multiple carbon fibers The core or thread 10 to be constructed comes out of a reel (not shown) and is placed in a tank 13. It advances onto the roll 11 installed on top of the electrolytic bath 12, and then continues on top of the bath 12. It advances onto two rollers 14 immersed in it, and finally a take-up reel (not shown). Before being wound up, it reaches a roll 15 placed on the tank.

Roll 15 (and any other rolls) are not shown to continuously advance yarn 10. rotated by means.

Rollers 11 and 15 are connected to the anode output terminal of potentiostat 16 and Stainless steel immersed in solution 12 to give 10 a positive polarity with respect to the cathode. The cathode side terminal of the potentiostat 16 is connected to the coil cathode 17. Calome The reference electrode 18 is connected to the control terminal 19 of the potentiostat 16 and This allows the potential of the anode to be set to the desired value relative to the reference electrode. . This device can perform the same type of processing as the mechanism shown in Figure 1, except that The cases are carried out consecutively.

The apparatus for treating split carbon is schematically shown in FIG. The head is held by a fine platinum mesh 21 which acts as an anode, and the gas It rests on a porous disk 22 that closes a vertical cylinder 23 made of lath. Carbon 20 A second flatina 1424 located above the pad constitutes the cathode. standard Electrode 25 is inserted into carbon head 20. Enclosure 23 is filled with electrolyte 26 The electrolyte is caused to flow from the anode to the cathode by the pump 27. (with pump components in contact with a chemically inert electrolyte), an anode 21, a cathode 24 and reference electrode 25 are connected to potentiostat device 28 . This device is , performs the same type of processing as the mechanism in Figure 1, except that it is performed on the split carbon. It will be done. Next, a method for determining the degree of adhesion of carbon fibers to resin will be described.

One end of the separated fiber fragments is inserted into the moving ``jaw'' of the tensioner and soldered. while the other end is connected to the fiber by the force required to pull it out of the resin. Embedded in the resin by a short distance to ensure that the breaking strength is less than Ru.

The extraction force F4 is measured by a tensile machine. Filament breakage embedded in resin The circumference of the surface and the length L are measured by scanning electron microscopy. Greszo ZUK established the theory of extraction tests. he shear between fiber and matrix The stress τ is maximum at the point where the filament enters the matrix; The decohesion of 0 decreases with increasing distance from the At the moment τ reaches the fiber-matrix separation stress τ4. τ4 is It is given by the following formula.

Fα τa --c o t h α is the shape of the filament accepted in the matrix and the young This is a coefficient that takes into account the shear modulus of the resin. The experiment is given by Give access to the average separation stress τ.

y=Fa/pf Therefore y=(t4tanhcxl)/an correction is required. per filament By changing this length, it can be applied to the above equation using the least squares method. A curve y=f (1) is obtained. τ4, i.e., the separation stress at the interface is Thus obtained, due to the adhesion of the fibers to the resin and resistance to shear forces The properties of the fiber-resin interface are known. Plotted in Figure 13.14 Each point is obtained from a series of measurements of τ−f (j), from which τ4 is Estimation of τ6 with 68% confidence interval (confidence 1nterval) Entaku is played with some errors.

Examples 1 to 3 below are taken from the aforementioned French patent no. 2,564.489. However, the value of τ4 is based on the fibers accepted in the resin as described above. has been modified to account for the effect of length. However, the results shown in the above patent are The effect of this modification, which does not take this modification into account, is Slightly increases the value of τ1, which is given in Example 4. A more accurate comparison of the results obtained according to the invention with the corresponding results is obtained.

The values of τ4 given below have all been corrected, and the error of τ4 is 68%. estimated with a confidence interval of

Implementation example 1 By C0URTAtLDS LIMITED using the equipment shown in Figure 1. The untreated HT type carbon fiber manufactured by 50r9 hexamethylene per tl with a potential of +1.45 volts to the poles It was treated in an electrolytic bath consisting of an aqueous solution of lentoramine at pH 8.62. The processing is It was carried out at 20°C.

The specimens for measuring the interface separation stress τ4 were heated at 140 °C for 2 hours. After that, CIBA GEIGY Aral was cured at 60°C for more than 16 hours. Daito LY556 resin (bisphenyl A diglycidyl ether) HT972 curing agent (4-4'diaminodiphenylmethane) Prepared for use with.

Figure 13a corresponds to Table I and shows the variation of τ4 as a function of processing time. It shows. The processing significantly increases τ4, and τ4 almost decreases after t-10 minutes. It will be observed that it is stable.

Table■ Processing time Separation stress (minutes) τa (MPa Untreated fiber 28.1±2.5 3 44.3±3.3 10 65.5±4.7 60 68.3±2.9 Figure 6 shows untreated cabby C) and treated for 10 minutes, respectively. (d, e, f), 60 minute processed sushita potatoes (D (g, h, i) (7) C OURTAULDS (7) ESCA and SIMS spectra obtained from HT woven fibers It shows the The peaks of C1s and N1s (ESCA) are shown in Figure 7. Shown in detail.

The ESCA analysis (Figures 6a, 6d, 6g) first of all examines the outer layer of the fiber, i.e. To determine the physical properties of the elements present in a layer of thickness Hm (50 angstroms) Second, it is useful for obtaining information on the chemical bonding states of these elements.

The 31MS spectrum is based on the -order argon ion beam, approximately 0.5 Hm (5 Å The peak corresponding to the elemental composition present on the fiber surface under the thickness of The peak at mass 24 (CC - secondary ions) are characteristic of the carbon substratum, and as a reference used. The peaks at masses 25 and 36 are mostly due to untreated fibers containing no nitrogen. It corresponds to ccH-1CCH,- ion. For treated fibers, with a mass of 26 The peak contains CCH,- ions and CN- ions derived from nitrogenous surface groups, A convenient way to determine the degree to which the fiber surface is enriched with nitrogen is to calculate the ratio R(N) defined by the following formula: is to use.

Peak height at mass 26 R(N) = □ Peak height at mass 24 The ratio R(0) in the case of oxygen is calculated using the peaks of masses 16 and 17 (0- and 0H-). is defined similarly.

Table ■ shows the analysis results.

Table■ Processing time Average composition of surface layer (5Hm) SIMS (min) χCXN 2OR ( N) R(0) Untreated fiber 96 0.5 3.2 < 0.25 0.440 81 9 9 5.9 0.25 These despite the fact that the treatment added at least as much oxygen as nitrogen. The test results show that nitrogen is actually located on the fiber surface, while oxygen is distributed below the fiber surface. This indicates that the

Figures 5c, 6f and 6H show positive S IMS ion spectra, i.e. positive secondary On spectrum is shown. Figure 6f (t-10 minutes) shows that every 15 units of mass It shows the range of a certain peak. These ranges cover the spectrum of untreated fibers. These levels are absent from the spectra of fibers treated for 60 minutes and 60 minutes (Figures 6c and 6H). The waves are features of surface molecules containing cHzs that are shattered by the -order beam. child This means that after 10 minutes of operation, most of the hexamethylenetetramine molecules are exists on the surface, but after 60 minutes of operation, -NH and -NH groups are It means that it remains on the surface of the fiber. Hexamethylenetetramine molecule is , the electrochemical reaction gradually degrades without a decrease in τ1. ), -NH, and -NH group are hexamethylenetetra Since it is smaller than the min molecule, R(0) is smaller at t-60 minutes than at t-10 minutes. The larger one is normal.

FIG. 7 shows the corresponding C1s and N's photoelectron peaks. t=10 minutes and t-60 minutes (Figure 70,7c), the C1s peak is Compared to the C1s peak in Figure 7a), it has a shoulder, and carbon has a higher charge than itself. This indicates that it is partially combined with highly aeronegative elements, especially nitrogen. Nlsbi The curves (Fig. 7b: untreated, Fig. 7d: after lO min, Fig. ?f: after 60 min) are asymmetric. Ru. These shapes and bond energy levels are similar to those in the presence of -NH and -NH groups, This indicates that it is covalently bonded to the underlying layer.

Implementation example 2 The treatment was carried out using amino 6 methyl 2 pyridine (primary amine) as the electrolyte. Ta. The bath was an aqueous solution of amine 6 methyl 2 pyridine with a pH of 10.06, 25 g/l. Yes, +1.5 vs. C0URTAULDS HT woven fiber saturated calomel reference electrode The potential was in volts. The treatment was carried out at 20°C.

τ was measured by the procedure used in Example 1.

FIG. 13b corresponds to Table 2 and shows the variation of τ4 as a function of processing time. child The curve has the highest value around 10 minutes after operation, and the τ4 value obtained at this time is the actual value. This is very close to the value obtained in Example 1 after the same processing time.

Table■ Processing time Separation stress (minutes) τa (MPa) Untreated fiber 28.1±2.5 2.5 44.3±3.3 5 46.7±7.5 10 70.3±3.4 60 59.6±3.3 Figure 8 shows a set of ESCA and S1MS spectra after 1 hour of treatment. There is. ESCA analysis (Figure 8a) showed the following values:

-C: 12% -N: 16.7% (analysis value at 5 nm thickness) -0: 10.5% Using SIMS analysis, the ratio of nitrogen and oxygen on the surface is -R(N)-4 (negative S (See Figure 8b showing IMS) -R(0)-0,13 Met.

The C1s and Nls peaks (Fig. 8b, Be) indicate that nitrogen is carbon, similar to the first example. It can be seen that the covalent bond with the element is located on the surface of the fiber. Hexa The peak designated as Hl (after t-60 min) was Compared to Figure 8e), the peak of Nls has shifted to lower binding energy. This means that the ESCA analysis shows that the pyridine ring of the amino 6-methyl 2-pyridine molecule is bound to the Nitrogen is present at the surface due to the fact that we detected nitrogen This means that in the explicit SIMS measurement (Figure 8c), the peak range changes every 14 mass units. This is proven by the detection of Even after 60 minutes of operation, amino 6 methyl 2 All molecules of lysine are still grafted. This grafting is characterized by amine action. (amine function) caused by nitrogen. The same operation This was done with chill 2 pyridine. It does not contain the NH, group of amino 6 methyl 2 pyridine. According to the analysis results, this molecule has only 1.6% nitrogen bonded ( ESCA), R(0) is as small as 1.4, and in amino 6 methyl 2 pyridine The range of the observed peaks is extremely attenuated (Figure 8f), due to the nitrogen in the pyridine ring. Elements hardly participate in electrochemical reactions.

The maximum value of the τa-f(t) curve (Fig. 13b) is thereby Partial proton deprivation (depr Few of the 0 molecules that may be related to o ton iz iB) has probably lost its activity with respect to fiber-resin adhesion.

Implementation example 3 The treatment was carried out using urea as electrolyte. This substance has two amino groups. It is a minoamide. C0URTAULDS HT carbon fiber can be used with the equipment shown in Figure 1. pH 7.42, urea 50 g/It aqueous electrolyte bath, saturated calomel group The fibers were treated with a potential of +1.5 volts relative to the quasi-electrode. The processing temperature is 20 It was ℃. τ4 is the ′th! Measured using the procedure of the example.

FIG. 13c corresponds to Table 1 and shows the variation of τ as a function of duration.

Table■ Processing time Separation stress (minutes) τa (MPa) Untreated fiber 28.1±2.5 10 61.2±5.3 60　69.3±3.3 A very high increase in τ4 was also obtained in this example.

After 1 hour of operation (see Figure 9a), the ESCA showed the following results.

C near 6.3% N: 5.9% 0:17.8% Shadow SIMS (see Figure 9b) showed the following results.

R(N) -4,3 R(0) -1,8 Although the concentration of oxygen is considerably higher than that of nitrogen, the surface is still quite rich in nitrogen. It shows a large value. The C1s peak (Figure 9d) is shown in the first and second examples. It has a shoulder similar to the peak. The Nls peak (Figure 9e) is Lower binding energy compared to the Nls peak of sameethylenetetramine (1st example) - biased toward In negative SIMS (see Figure 9d), it corresponds to CN0- ion. A peak can be seen at mass 42.

In positive SIMS (Figure 9c), CON! Compatible with "and C0Nff1H'" ions Peaks are seen at possible masses 56 and 57. Therefore, the urea molecule is There is a very high possibility that it has been copied.

Examples 4, 5.6 below were carried out in non-aqueous media.

Implementation example 4 The electrolyte was 12 g of ethylene diamine (2 21g of lithium perchlorate per 12 Added as an auxiliary electrolyte. C0UI? The HT woven fiber potential of TAULDS is 0.0 containing acetonitrile. OIM　Ag/Ag’″ +1.3 volts with respect to the reference electrode It was. The temperature was 20°C, and the experimental setup was as shown in Figure 1. . τ4 was measured by the procedure used in the first example.

Figure 14a shows the resin coated with Araldite LY556+HT972. τ4 is shown as a function of processing time for the fibers prepared.

Figure 14b is available from the NARMCO Company and primarily acts as a curing agent. From tetraglycidyl methylene dianiline and diaminodiphenylsulfone These are the results obtained using NARMCO 5208 resin.

The results are shown in Table V.

Table V Processing time Separation stress τ4 (MPa) (minutes) LY556 resin NARMCO 5208 resin untreated fiber 28.1±2.5 60.9±5.11.5 48. 8±3.3 97.7±5.35 73.4±3 105.5±6.55 minutes The following results were obtained from surface analysis after multiple treatments.

According to ESCA, -C: 66% -N: 22% (see Figure 10a) -0:11% According to S IMS, −R(N) −22 (see Figure 10b) −R(0) = 2.7 The C1s peak (Figure 10d) is due to the very high R(N) and nitrogen concentration. A large portion of carbon is covalently bonded to atoms that are more electronegative than carbon, especially nitrogen. It shows very large shoulders indicating that Again, with R(N))R(0) Yes, nitrogen is concentrated on the surface.

Oxygen due to traces of water in solution is located below the surface. Nlsbee The asymmetry of the square (Figure 10e) indicates the presence of -NH and =NH groups on the surface. are doing. Despite the size of the Na″″ peak, positive S IMS (Fig. 10c ) shows the existence of two small ranges of peaks at masses 28 and 42. There is. It is likely that ethylenediamine molecules are grafted onto it.

The following considerations can be obtained from these results.

This operation is more effective than the operation in an aqueous medium shown in Example 1.2.3. It is most suitable for grafting nitrogen groups quickly and with higher density.

However, the separation stress τ4 is a water-based resin using CIBA GEIGY's LY556 resin. Substantially no larger than that obtained in the medium.

Therefore, the interface made of this resin has a shear strength of greater than about 70 MPa. It is considered that it cannot withstand stress. In contrast, NARMCO5 If 20B resin is used, the process reaches its highest value after about 2.5 minutes (14th b. ), and the shear stress reaches up to 105.5 MPa (see Table V).

The τ of NARMCO5208 resin is the same as that of CIBA GHIGY's LY556 resin. It should be noted that the untreated fiber has a pressure of 60.9 MPa compared to 28.1 MPa for the untreated fiber. It is possible. This indicates that NARMCO 5208 resin has a C It has higher reactivity than IBA GEIGY's LY556 and has no surface groups. Explained by considering directly producing fiber-matrix bonds and (similarly, , NARMC0520B resin can achieve maximum adhesion in 2.5 minutes of operation. It reacts more easily with the grafted surface groups.

Using "high strength" fiber available on the market under the trade name τ0RAYT300 90A The τ4 measurement conducted was ra-6 for CIBA GEIGY's LY556 resin. It shows a value of 1 ± 4 MPa, and this value is different from aqueous medium (Example 1.2.3) and non-aqueous medium. lower than the value obtained using the medium (fourth example), thereby containing amines. The usefulness of treatment using electrolytes was demonstrated.

The effect of working voltage in non-aqueous media is explained by the following result * A g / A　g　With respect to the reference electrode, perform the following results under the same conditions except for Vt-+1 volt and t-5 minutes. The fruit was obtained.

τ--67,3±2.9M P a C near 0.7% N: 17.6% 0: 9.4% R(N)-15,2 R(0)-1,7 It was found that the separation stress was hardly affected by the decrease in Vt. In contrast, the surface The amount of nitrogen is reduced by about a quarter.

Implementation example 5 The electrolyte does not contain auxiliary electrolytes and is anhydrous acetonitrile 1J! 45g of amino 6 in It was a solution of methyl 2-pyridine. C0URTAULDS HT weave The fiber potential is + in acetonitrile relative to a 0.01M Ag/Ag'' reference electrode. It was 1 volt. The temperature was 20°C and the processing equipment was as shown in Figure 1. . The treatment time was 3 minutes.

Figure 11a shows the C1s peak of fibers treated in this way and Figure 11b shows the N ls peak, Figure 11c shows the negative SIMS spectrum, and Figure 1id shows the positive A C1s spectrum is shown.

From these we can see the following.

R(N) -3,8 R(0)-1 C-82.2% N-5.1% 0-8.2% The shoulder of the C1s beak shows that the carbon This shows that it is bonded to an element that is more electronegative than the element. energy level The shape of the and Nls peaks indicates that nitrogen exists in the form of -NH8 or -NH group. This is true because there is no peak range in positive SIMS. Despite the low potential Vt and no auxiliary electrolyte used, fiber A sufficiently biased and non-negligible amount of nitrogen grafting was observed on the surface of (R (N) -3,8).

Implementation example 6 The electrolyte is anhydrous dimethylformamide 1j! 12g of ethylenediamine dissolved in It was. 21 g of lithium perchlorate was added to solution 11 as an auxiliary electrolyte. It was done.

COυEdited＾ULDS HT woven fiber, +1.45 volts vs. saturated calomel reference electrode (ESC, relative to a standard reference electrode of 0.0IMAg/Ag in acetonitrile) equal to +1.15 volts), or +1.6 volts for a saturated calomel electrode) (equal to +1.3 volts with respect to the reference electrode of A g / A g ”). In addition, the treatment temperature was 20° C. and the treatment time was 5 minutes. The experimental equipment is shown in Figure 1. I used what was available.

The spectroscopic analysis of the corresponding surfaces (Table ■) is shown in Examples 1 to 5 and Example 7.8. This was done using equipment different from that used in This second device is has been calibrated so that the results obtained can be compared with those obtained in other examples. Ru. In this case, a scale of energy of photoelectrons (ESCA) is divided. child In the case of , the photoelectron energy scale (ESCA) is relative to Mg Kα radiation. is taken and its kinetic energy is displayed. In other embodiments, the X-axis is The binding energies E and B of photoelectrons emitted from the electrons are displayed.

Table■・ Vt-+1.45 bore L/T/EC5Vt-+1.6 bore) L')/ECS Time-5 (minutes) Time-5 (minutes) ESCA C: 75.5χ C near 6χ N: 13χ N: 11χ 0: 11.5χ 0:13χ SIMS “R(N)・6.OR(N)・2.9R(0)・1.6R(0) ・0.21511'Is - Chlorine and lithium present Although the effect is lower than the treatment recorded in the fourth example (solvent - acetonitrile), carried out using dimethylformamide, especially at Vt-1,45 volts/E SC In this process, a significant amount of nitrogen is distributed to the surface of the fiber.

The results at Vt-+1.45 volts/ESC are from a grafting perspective. is comparable to that recorded in the first example (after t-10 minutes and after t-60 minutes) However, the processing time is much shorter (5 minutes).

Figure 12a shows the C1s peak after treatment at Vt = 1.45 volts/ESC. There is. Large shoulders biased toward low kinetic energy (high binding energy of atoms) indicates that carbon is chemically bonded to an atom that is more electronegative than carbon. ing. The Nls peak (Figure 12b) is E, B = 339 eV (kinetic energy - is centered at 854e■), and acetonitrile (see Example 4, Figure 10e) The value is exactly the same as that seen in the 5-minute Nls peak operated with There is. Therefore, nitrogen is covalently bonded to carbon. Figures 12c and 12d are shaded. and a positive SIMS spectrum.

Figure 12e shows the C1s peak of the treatment at ■also=+1.6 volts/ESC. are doing. The width at half height is wider than that of t = 1.45 Porto/ESC (7) , Figure 12f shows the corresponding N1g peak centered at E, B = 399.8 eV. , which is shifted by 0.7 eV with respect to Vt=+1.45 volts. E in oxygen , B=534. In leV, in contrast, at Vt = +1.45 volts, E, B = 53 It is 2eV. This is because nitrogen, oxygen and carbon are present in dimethylformamide. This shows that the two processes are not in the same bonding state. Figure 12g, Figure 12h shows the negative and positive S1MS spectra.

In the negative S 1MS spectrum (Figures 12c and 12g), chlorine (mass 35.37 ) was observed, and the richness was observed in the positive SIMS spectrum (Fig. 12d, Fig. A very large peak due to U (mass 6.7) was observed.

Therefore, lithium perchlorate is involved in the electrochemical reaction, and ■. L (i.e. dimethylformamide + 2 volts for Lic104) too close to There is no advantage to doing so. This means that nitrogen grafting is Vt = +1.6 volts. /ESC has less (R(N) is 2.9 and Vt-+1.4 At 5 volts/ESC, R(N) = 6, nitrogen fixation is 11% and 13%, respectively), However, nitrogen is unevenly distributed on the surface in the form of -NH and =NH groups, and is effective. Since R(0) is still small, oxygen exists below the surface. Continue to do so. Separation measured using the apparatus of Example 1 and NARMCO 520B resin The stress is: τa=1034±3MPa at Vt=+1.6 volts/ESC Met.

Since R(0) is only 0.21, oxygen hardly contributes to the adhesion force. I can't.

Implementation example 7 The conditions of Example 1 were initially untreated but treated with hexamethylenetetramine for 1 hour. Applied to HMU fiber of “high module” COS RTAIILDS which underwent . Initially, τ4-15.2 + 1.7M P a (CIBA GEIGY's LY 556 resin), after 1 hour of treatment, r = 15.2 ± 4.9 MPa. became. This indicates that the surface of these fibers is sensitive to the electrochemical reaction carried out in Example 1. meaning that it is inert.

These C0URTALILDS HMU fibers generate electromagnetic waves with a frequency of 12.57MHz. exposed to the action of nitrogen plasma generated by waves. Experimental equipment in the laboratory It is shown in FIG.

A segment 31 with a length of 5 cm is placed inside a cylindrical channel 33 cooled by running water. It was placed on a graphite support stand 32. Two external annular electrodes 34 serve as high frequency generators. It was connected to station 35. Nitrogen micro leak 37 with pump 36 controlled The inside of the container was maintained at a nitrogen pressure of about 15 Pa. spent on nitrogen plasma The power generated was approximately 100 watts.

Plasma treatment was carried out continuously on the carbon fibers by suitable equipment (not shown) .

In the state of Example 1, τ4 was changed from 15.21±1.7M P to 64.7±7M. To increase to 4MPa, the fibers of HMU of C0URTAULDS are heated for 30 seconds. Exposure to the action of plasma is sufficient. Ion bombardment exists on the fiber surface. release carbon atoms from large molecular weight aromatic substances. In this way chemical An active place will be created. No nitrogen was detected in ESCA and SIMS. , the observed small addition of oxygen is unlikely to be sufficient to explain the increase in τ6. For this reason, these increase the surface active power of C0URTAULDS HMU fibers. This means that it will be added. Thus, the surface of these fibers is CIBA GEIGY's HMU resin is fully activated so that it can be directly attached to it. It will be done. These plasma-treated fibers have a surface structure containing numerous defects . Reorganization of the electron cloud around an absent carbon atom allows the use of unsaturated chemical bonds. Continue to make it possible. Direct crosslinking is possible between fiber and resin. Even more powerfully, The surface of the fiber is sufficiently saturated to react sensitively to the electrochemical treatment reactions described above. activated in minutes.

Implementation example 8 The original untreated C0URTAULDS HT woven fibers were treated for 1 hour under the conditions of Example 1. of epichlorohydrin in a HT woven fiber sealed container of C0URTAULDS placed in existence. Infiltration was carried out at 120°C for 22 hours. epichlorohydrin has an engineered poxy group. Because the fiber removes epichlorohydrin from its surface was washed three times with acetone.

Figure 15a shows the HT woven fiber CIS peak (ES CA) is shown. Figure 15b shows hexamethylene in an aqueous medium for 1 hour. The C1s peak after treatment with Tolamin is shown. Figure 15c shows epichlorhydride Figure 3 shows the CIS peaks of untreated fibers after exposure to the action of phosphorus. lastly, Figure 15d shows the effect of hexamethylenetetramine surface treatment and epichlorohydrin. The C1s peak of exposed fibers is shown.

Figures 15a and 15c show untreated fibers and treated fibers (Figures 15b and 15c). Unlike Figure d), this shows that epichlorohydrin is not fixed. 1 hour After treatment (see first example), the surface has only the grafted =NH and -NH groups. Therefore, the very large shoulder of the CIs peak in Figure 15d is due to the epicronic Ruhydrin combines with nitrogen on the surface of fibers treated with hexamethylenetetramine. 0 surface groups shown to be bonded via carbon-nitrogen-resin covalent bonds. to give cohesiveness to the interface.

The results described above are similar to those observed with respect to the grafting of nitrogen groups or molecules. This gives us confidence that the effects arise from a common mechanism.

Amines (primary, secondary, and tertiary amines) investigated electrochemically on platinum anodes. Anodization (which may be offset) is generally done by forming a cation radical that is followed by a cation. For example, in the case of a primary amine where R is a group that is resistant to redox under the experimental conditions, If so, RCHzNHt -e-: RC)ItNHl -u'=RCHNHt -e -: RCHgNHl” cation radical cation The presence of cationic groups (radicals) is due to the presence of tetramethyl base using carbon fiber as the anode. RAMAM red in a solution of acetonitrile containing didine and lithium perchlorate. Confirmed by external beam spectrometer. The cationic group exceeds the first redox potential of the amine. cation appears when the second potential is exceeded. Ru.

Since cations cannot exist in water, cation radicals are primary and secondary amines. Carbon is produced in an aqueous medium as soon as it is produced by the following mechanism applied to be attacked.

radical cation The carbon atoms in these reactions are surface atoms of the fiber.

Radical C. can combine with cation radicals. 0 reaction is electrolyte solution. neucleophilic reactions such as OH- ions present in It is possible with family.

Co-e-1 → C4 C"+0H--→C-0H C-OH-H”-e---C=0 The latter two reactions involve a small amount of oxygen remaining on the actual surface of the fiber (in an aqueous medium). Give a reason for the existence of groups.

For tertiary amines: The proton deprivation step (deprotonizing 5 steps) consists of three groups R′, One of R', R' is removed (replaced by).

These mechanisms that apply to aqueous media can also be applied to non-aqueous media.

Cations are stable to some extent in organic solvents and can react with carbon in fibers. . This reaction combines Co radicals and acids as long as the solvent is properly anhydrified. This suggests that the element remains in extremely small amounts.

In these reactions, the operating potential Vt is larger than the redox potential of the amino compound, The operating potential Vt is the decomposition potential of water v0 or the potential of a non-aqueous solvent with an auxiliary electrolyte ■, . , occurs when it is smaller.

When operating in non-aqueous media: The decomposition potential is determined by the fact that any auxiliary electrolyte used has a high electrochemical Insofar as it has an oxidation potential, it will be at a higher potential; ■3° is not reduced by compounds with low PKb as in the case of water; Nitrogen groups such as NH and =NH or all molecules of the amine acting as an electrolyte are is mostly grafted by covalent bonds, The amount of nitrogen surface groups grafted increases compared to treatment in aqueous media, and this is particularly Occurs more quickly when acetonitrile is used; The adhesion obtained is very high; By achieving the above-mentioned potential conditions, on the surface of a suitable type of carbon or e.g. For example, an activated surface of carbon treated by a suitable method such as the use of plasma. It becomes possible to graft a wide range of amine molecules onto the surface.

Aqueous medium Non-aqueous medium Special edition Showa 64-500133 (16) 78iBr164-500133 C17) Td MPa ab Cd international search report

Claims (17)

[Claims] 1. Carbon is brought into contact with a solution of an amine compound in a dipolar solvent to create a positive polarity for the cathode. A method for electrochemical surface treatment of carbon to impart polarity, wherein the solvent is a highly anodic acid an organic solvent having a chemical potential, wherein the solution is substantially free of water. 2. The amine compound is ethylene diamine, amino 6 methyl 2 pyridine and tetamine. The method of claim 1, wherein the method is selected from lamethylbenzidine. 3. 2. The method of claim 1, wherein said solvent is aprotic. 4. The organic solvent is acetonitrile, dimethylformamide and dimethylsulfate. 4. The method of claim 3, wherein the method is selected from phoxide. 5. Claim: An auxiliary electrolyte having a similarly high anodizing potential is added to said solution. The method according to the first term of the scope. 6. The auxiliary electrolyte is lithium perchlorate, tetraethylammonium perchlorate, Selected from tetrafluoroborates and alkaline or quaternary ammonium tetrafluorophosphates. The method of claim 5, wherein the method is disclosed. 7. Polarization of carbon by anodization of dipolar solvents and auxiliary electrolytes if present low enough to avoid anodic oxidation, and low enough to expose the amine compound to anodization. The first method is highly selected. 8. The solution is composed of ethylenediamine, acetonitrile and lithium perchlorate. The potential of carbon with respect to the 0.01M Ag/Ag+ electrode is approximately 1.3 volts. The method of claim 7. 9. The solution contains ethylenediamine, dimethylformamide and lithium perchlorate. The potential of the carbon relative to the saturated calomel electrode is approximately +1.45 volts. The method of claim 7. 10. Carbon treated by the method of claim 1. 11. Treated carbon according to claim 10, comprising carbon-nitrogen bonds on the surface. 12. The surface contains all or some molecules of -NH2 and =NH groups or amine compounds. A treated carbon according to claim 11. 13. Carbon is microporous carbon, carbon that can be graphitized at low temperatures, and surface activated carbon. 11. The treated carbon according to claim 10, which is obtained by treating carbon selected from the raw materials. 14. Claim 13, the surface of which is activated by the action of nitrogen plasma. Processed carbon by term. 15. Treated carbon according to claim 10, wherein the carbon is in the form of carbon fibers. 16. having a matrix reinforced with carbon fibers according to claim 15. composite material. 17. Claim wherein the matrix is an organic resin crosslinked with an amine curing agent. Composite materials according to scope item 16.