DE1646658B2 - Process for the production of carbon moldings of different, from the porous to the dense state reaching microstructure from modified pitch - Google Patents

Description

The invention relates to a method for the production of carbon moldings of different, from the porous to the dense state of the structure of modified pitch, which is enough Tar or pitch is obtained, which 1) for the purpose of achieving easy graphitability in one inert gas atmosphere of a heat treatment, 2) for the purpose of achieving a difficult graphitizability in one or more oxidizing gases such as oxygen, ozone, halogens or sulfur, a heat treatment, 3) for the purpose of making it easy to graphitize a solvent extraction or 4) following one or more of the above-mentioned process steps 1) to 3) for the purpose of achieving a corresponding graphitizability are subjected to a dry distillation, the from the modified pitch-shaped body is carbonized or graphitized after carbonization will.

It is generally known to produce objects or structures of pronounced shape from carbon.

In particular, US Pat. No. 035 308 describes a process for converting coal tar and coal tar pitch in easily graphitizable pitch coke known for the production of highly conductive Graphite electrodes are used. In this known method, the raw material is first of all Sooty substances and components that are insoluble in acid-free organic pitch solvents are freed are heated, the refined starting material for the production of coke and finally the Pitch coke obtained is shaped into electrodes and graphitized by heating. The easily graphitizable material However, it was not used solely for the production of carbon molded bodies, but as an aggregate in conjunction with used a binder. The known method thus primarily deals with the refinement of Coal tar and the use of the pitch coke obtained together with other materials for Production of carbon moldings that can be easily graphitized.

From the German patent 817 269 a process for the production of carbon moldings from pitch is known, from which free carbon is obtained after several operations in an oiler, which is then pressed into a desired shape ^{under a pressure of about 640 kg / cm 2 and used as a} Molded piece is heated in a non-oxidizing atmosphere to a temperature not below 550 ° C, the temperature rise being kept fast, but not so fast that the molded body swells as a result. In contrast to this known method, in the subject matter of the invention, the shaped body should not be formed from deposited free carbon, but from a modified pitch which is carbonized and optionally graphitized after molding. In the known method, the use of binders is recommended to promote the caking of the free carbon.

From US Pat. No. 2,697,028 it is known to produce bodies from coal tar distillation residues shaping and heating the shaped bodies for carbonization in a non-oxidizing atmosphere, namely to a temperature at which all the hydrogen and oxygen from the shaped bodies is driven. However, this known method is based on the presence of divinylbenzene or of switched off from another vinylbenzene and makes use of addition polymerization.

Furthermore, the German Auslegeschrift 1 209 037 discloses a method for producing carbon molded bodies known, according to the initially particles of natural pyrobitumen, which itself is not sufficient Verpreßbariceit shows and can only be viewed as an aggregate, with asphalt bitumen as a binder are mixed, the mixture formed into a shaped body, the shaped body at increased Temperature of about 170 ° C to 300 ° C under the action of oxygen is treated to the binder bitumen to convert into infusible pyrobitumen, and finally the shaped bodies be carbonized.

The invention is based on the object of producing carbon molded bodies, their graphitization properties Selectable in a range from easy to difficult graphitability and their structure ranges from dense to porous, a simple and a little to create complex process that gets by as a starting material with types of pitch, which by a can be modified with little effort, and at

basically no additional binding agent! required are.

To achieve this object, the method according to the invention described at the outset is characterized in that a modified pitch with a hydrogen / carbon atomic ratio of 0.2 to 0.6 and with a softening point of at least 170C is crushed into powdery fine particles Pressure in the range from 100 to 3000 kg / cm ^{2 is} pressed into a desired shape and then the molded body produced in this way is ^{heated in an oxygen-containing atmosphere to a temperature between 200 "C and 330 D} C, based on a temperature increase of 0 , 1 to 3 ° C / min.

The details of the invention are to be explained in more detail below on the basis of exemplary embodiments and the scope must be specified. From the following it can also be seen that the inventive Manufacturing process is not only easy to carry out, but also to carbon moldings with excellent performance properties.

"Modified pitch" is to be understood as meaning all types of pitch that are produced by heat treatment, by treatment with a dehydrating agent such as ozone, oxygen, air, halogens and Sulfur, or a solvent extraction treatment from coal tar pitch, Petroleum asphalt and other types of tar and pitch that arise as industrial by-products, be won. These modified pitch types are further characterized in that at them the hydrogen / carbon atomic ratio is between 0.2 and 0.6 and the softening temperature 170C or higher.

The "softening temperature" or the "softening point" should be understood as the temperature at which a sample in the form of a fine powder of the order of magnitude of about 0.1 mm in a closed tube assumes a completely spherical shape, for which a micro-melting point measuring device is used. Numerous types of modified pitch with a hydrogen / carbon atomic ratio of the order of 0.60 to 0,4ö show softening points in the range 170-300 ^0C

Pitch types with a hydrogen / carbon atomic ratio of 0.46 to 0.40 take when they are in Powder form are heated, not a pronounced molten state, but swell in many Cases on heating when molded or cast in an inert gas atmosphere under pressure were, the swelling due to the training a semi-molten state and caused by the generation of gases. Even if the pitch types with a hydrogen / carbon atomic ratio of 0.4 to 0.2 are not pronounced have a molten state when heated in powder form, or not a semi-molten one If they are heated in the form of a pressed vessel, these types of pitch show nevertheless sufficiently good sintering properties.

The described relationship between the hydrogen / carbon atomic ratio and the softening point changes to some extent, and? was depending on whether functional groups with high thermal reactivity are present in the modified pitch.

To shape the material, a single modified pitch or a mixture of different types of pitch is ground to a desired particle size or a combination of different particle sizes. The ground particles are pressed into a shape by compression molding at a pressure of 100 to 3000 kg / cm ^2. A feature of this process is that the incorporation of a filler such as coke particles or a binder such as pitch is not necessary. Additives such as coke and graphite can be added, especially when the softening point of the pitch is low.

The shaping according to the invention can be done by injection molding or pressing in an injection mold, compression mold or perform a hollow shape. In both cases, good results have been obtained by using the for example, about 10% or less alcohol is added to modified pitch.

In a modified pitch having a softening temperature of 300 ⁰ C or less, the molding of the pitch is performed first, then brought the pitch dried, and then in air gradually to a temperature of 200 to 30O ⁰ C, wherein the temperature rise between 0.1 and 3 ^J C / min.

The following are some general properties of the carbon products that are found after the Process according to the invention can be produced. ,

1. Depending on the softening point of the modified pitch and the molding pressure Articles with a porosity in the range of 8 to 60% can be produced.

2. These articles generally have a high degree of hardness. The Shore hardness of an object made of carbide with a porosity of about 30% or less is 80 to 130. If the object has been subjected to a graphitization treatment (at 280O ⁰ C), then the Shore hardness is 50 to 90 with a porosity of about 30 %.

3. The specific bulk density of these articles is 0.7 to 1.8.

4. The mechanical strength of these objects depends on the porosity and the specific bulk density. In general, the strength is high for carbonized articles and lower for graphitized articles. Objects with a porosity of 8 to 15% have a flexural strength of 800 to 1100 kg / cm ² , objects with a porosity of 15 to 30% have a flexural strength of 400 to 800 kg / cm ² and objects with a porosity of over 30% Flexural strength from 100 to 400 kg / cm ² .

Objects with a porosity of 8 to 15% that have been ^{subjected to a heat treatment at 600 °} C. have a flexural strength of 100 to 200 kg / cm ² and a Shore hardness of 100 to 130.

5. Among the measured physical properties of these molded articles, the graphitization properties gave the most surprising result. A molded article for a modified pitch is used as starting material which was recovered at a temperature of about 450 ⁰ C as the distillation residue and then oxidized 'at about 250 ⁰ C, for example, shows with respect to X-rays properties that a slightly properties graphitized carbon materials, although the modified pitch used as the starting material has an oxygen content of 15 to

5 6

25%. In contrast, a molded high porous state shows rich and simultaneous

Object for which the starting material has a modifiable basic structure, that of easily graphitizable

ornamental pitch is used, which ranges from dry properties to difficult-to-graphitize properties,

distillation with blowing air at one temperature. This feature extends the range of application

temperature of over 380 ⁰ C is produced, with respect to 5 both the vitreous and the porous carbon

X-rays the property of carbon material materials.

materials that are very difficult to graphite, Another advantage is that

although pitch types are used in the starting material on analytical development of carbon materials

Paths no oxygen can be detected. that from the industrial point of view as

In order to explain these characteristics further, extremely economical raw materials were designated.

the relationship between the modification process can be net.

the types of pitch used as starting materials and To fully describe the invention,

show the graphitization properties of the manufactured and the large area of application,

Investigated coal materials. In the following, specific exemplary embodiments are shown

the following: 15 specified of the invention.

1. Modified types of pitch used as distillation return

Stand can be obtained by dry distillation, Example 1
and modified types of pitch obtained by this process, coal tar pitch with a softening point of and then dry-distilled by a process 85 "C, for 60 minutes at 380 ° C, to introduce a thermally reactive 20. Then 20 g of the extraction substances, the functional group or a In other methods, if the constituents soluble in η-hexane are treated such as chlorination or oxidation, parts of the residue from dry distillation have been given up slightly graphitized carbon materials and removed, dissolved in chloroform Room temperature air with ozone through animal properties. As the solution passed. After removal of the chloroform

2. Modified pitch, which was ground by dry distillation, the remaining substance. The water, blowing in air as the distillation residue, is the substance / carbon atomic ratio of this substance. or by aftertreatment of this residue by 0.43, and the softening point was between Chlorination or oxyadion can be produced at 238 and 245 ° C.

to which a dehydrating agent is added and modified

adorned pitch types made by a combination of 400 kg / cm ² into a disc with a diameter

These processes are produced, result in carbon of 20 mm and a thickness of 10 mm pressed. the

The fabric of the difficult-to-graphitize disc was exposed to air at a temperature of 320 ° C

Carbon materials heated up to carbon materials with a temperature rise of 2 ° C / min,

with medium graphitization properties are sufficient. 35 The object was then placed in a nitrogen

It is therefore easily possible to ^{bring shaped carbon atmosphere and to 1000 0} C with a tempe-

Manufacture painting materials that heat a range of carbon rise rates of 5 "C / min.

Fabric materials that are easy to graphite cover the article heat-treated in this way

and which are difficult to graphitize, and a very uniform and had according to ⁽¹ Jm polishing

Have porosity range from 8 to 60%. 40 a mirror-like surface. The other properties

In the carbonization process step, the following were:

linear shrinkage coefficient 5 to 20% being Shore hardness (Hs) 100 to 115

in most cases between 10 and 15% has porosity ΠΎ

Since the physical properties of the after shrinkage "'.'.'.'.'.'.'.'.'.'.'.'.'. 15%

Invention made carbon articles have a 45 specific bulk density ... 1.4

cover a wide range find the carbonization yield of the invention 87%

appropriate products have a wide area of application. Flexural strength 600 kg / cm ²

The objects produced according to the invention 00 ° i

pronounced shape with low porosity can This object was by heating on a, for example, electrodes, electrolytic plates, 50 temperature of 2800 ⁰ C in an inert gas graph

Structural materials, fire-resistant materials and animals. The resulting object has the following

Aggregates are used. Their properties are:

Manufacturing process repeated heat hardening, Im Shore hardness (Hs) 68

impregnations and renewed heat treatments reduce porosity \ (> ^a /

avoided. The articles formed with high porosity flexural strength of 300 kg / cm ²

tat can be used, for example, as electrodes for burning specific resistance '.'. !!! 7 -10 "* ohm · cm.

Fabric cells, filter elements and as tub insulating

Materials are used. The changes in the lattice spacing caused by

An important feature of the invention is that heat treatment at temperatures of 1600 ⁰ C

that 60 and more were produced by the method according to the invention were the same

Has the possibility, in a simple manner, of carbon as with easily graphitizable carbon materials

to produce materials in the vitreous state, which and amounted to 3.365 A for an object of

are easy to graphitize or difficult graphitization has been heat-treated at ^{a temperature of 28OQ 0 C,}

approximately properties have, and porous carbon $ fy ^{\: ·:} ·: - ■■ _, -. - « ₇

to produce materials that can be easily graphitized 65, -si ;;; i- example ζ

or difficult graphitization properties; £ in polyvinyl chloride powder was in nitrogen gas sen, i.e. carbon materials ^ dje CTtsprech ^ d: a

Their structure varies from a glassy state to a dull The pitch-like substance produced in the process had

7 8

a softening point of 195 to 202 ⁰ C. This was then the same process steps

powdery, used as a starting material sub- exposed, which was already in Example 1 before the graphi-

The punch has been spread out as well as possible and is described at the tiering step. The thereby formed

Oxidation in air on a temperature rise disc was uniform and could result in a mirror

heated to 200 ° C at a rate of 2 to 3 ° C / min. 5 the surface can be polished. The disc had that

A pitch was obtained with a hydrogen / carbon - the following properties:

material atomic ratio of 0.48 and with an Erwei Shore hardness (Hs) 110 to 125

chopping point from 280 to 285 C. Porosity 167

This pitch was ground and then at a shrinkage 207

Pressure of 450 kg / cm * to a disk with an io specific bulk density '.'. '. 1.45 °
Diameter of 20 mm and a thickness of 4 mm. Flexural strength 600 kg / cm ²
pressed. This disk was subjected to the same process steps as those in Example 1 before. . .
Graphitization step are described. The one on this example

Way formed article was uniform and 15 coal tar pitch with a softening point of

could be polished to a mirror-like surface 85 ° C was dry distilled for 30 min at 380 ° C,

will. The following properties were measured: The residue was ground and at room temperature

Shore hardness (Hs) 108 to 120 exposed to chlorine gas for 30 minutes at a temperature. That I

Porosity 16 yielding pitch had a hydrogen / carbon

_c ". , "" _. "■■ λ _Λ ο / ao atomic ratio of 0.41 and a softening point

Shrinkage _20/0 * β

Specific bulk density ... 1.42 vrazobeaüL

Flexural strength 800 kg / cm *. . This pitch was at a pressure of 300 kg / cm *

pressed and shaped in the same way as it

. -I ₁ already described in connection with Example 1

Example 3 was 25. Then the same procedural

A coal tar pitch with a softening point exposed to steps that in Example 1 before the graph of 85 ⁰ C was dry distilled at 380 ° C. The step in the process is described,
resulting powdered residue was dried at room The article thus formed was subjected to temperature-ozone, and then by uniformly and had after polishing a spat-heating up to a temperature of 200 ⁰ C in air for 30 terrain surface. The properties of the counter-oxidized. A first pitch material was created in the process. The status was as follows:

The chloroform-insoluble constituents of the Shore hardness (Hs) 105 to 120

Coal tar pitch was made in powder form for the purpose of oxidizing porosity 207

heated ^{to 200 °} C. in an air atmosphere. Thereby shrinkage 207

a second material resulted 35 Specific bulk density: Y. 1.40 °

The first and second materials were given a flexural strength of 350 kg / cm *.

Weight ratio of 1: 3 mixed, and the mixed 00 «

ung was ground using a pitch mixture _. .

with an average hydrogen / carbon example 6

Atomic ratio of 0.50 and with a softening factor of 40. A pitch was used as the starting material, which

point of 250 to 255 ° C. This mixture as a by-product of petroleum naphtha cracking

was a danger occurred at a pressure of 400 kg / cm ² and a softening point of 195

object of pronounced shape and then has up to 205 ° C and a hydrogen / carbon atom

subjected to the same process steps, the ratio of 0.54 This pitch was

already ground in example 1 before the graphitization step 45 and then at a pressure of 300 kg / cm ²

are described. The properties of this counterpart to a disc with a diameter of 20 mm

The status was as follows: and pressed to a thickness of 5 mm

Shore hardness (Hs) 115 to 125 ^D ! ^{ese Sch} ^ ^e ^ f ψ ^Lu ^ _o ^ ^nem . ^Tem Pff ""

Porosity 137 increased from 1 to 2 ° C / mm to 330 ° C and then heated

Shrinkage 107 50 in an inert gas atmosphere by heating

Specific bulk weight '. '.'. 1.50 i «» ^o C ^be ], ^a temperature rise of 5 ° C / min

Carbonization yield .... 89% heat treated. _t ^ u

Flexural strength 950 kg / cm *. , ^De . ^r g ^ ete object showed a good consistency

⁶⁶ formigikeit and was reflective after polishing

". 55 surfaces. Its characteristics were as follows:

_.,,. ^egg * ^pie ... _,. . Shore hardness (Hs) 98 to 112

Coal tar pitch of the same type as in the examples - porosity 15V

Jen 1 and 3 with a softening point of 85 ° C. Shrinkage 757

was dried to dryness at 380 ° C. for 60 minutes. The specific density: '. '. 1.46 °

The residue after the addition of 5% tetramethyl 60 t "w" f "tioVp; t eookir / cm ²

thiuram disulfide for one hour at 300 ° C heat bending strength 600 kg / cm

acts and then ground. A pitch was obtained with 35% graphite powder for this pitch material

a hydrogen / carbon atomic ratio of This mixture was added at a pressure

0.45 and pressed into an object with a softening point of 260 to 500 kg / cm ^{2, dei}

265 ° C. 65 then in air with a rise in temperature

-This pitch was heated from 0.5 ° C / min to 300 ° C at a pressure of 150 kg / cm ^{2 and then heated}

into a disc with a diameter of 20 mm by heating to a temperature of 2800 ° C

and pressed to a thickness of 10 mm. This disk was graphitized in nitrogen gas. This item

'' 409530/3 "

feV

Claims (4)

Claim: Process for the production of carbon moldings of different, from the porous to the dense state reaching microstructure from modified pitch, which is obtained from tars or pitches, the 1) in order to achieve easy graphitization in an inert gas atmosphere of a heat treatment, 2) in order to achieve a difficult graphitability in one or more oxidizing Gases such as oxygen, ozone, halogens or sulfur, a heat treatment, 3) for the purpose of making it easy to graphitize a solvent extraction or 4) following one or more of the above-mentioned process steps 1) to 3) subjected to a dry distillation in order to achieve a corresponding graphitability will, wherein the bodies formed from the modified pitch are carbonized or graphitized after carbonization, characterized in that a modified pitch with a hydrogen / carbon atomic ratio of 0.2 to 0.6 and with a softening point of at least 170 ⁰ C to powdery fine particles crushed, the pulverized pitch is pressed under a pressure ranging from ICO to 3000 kg / cm ² into a desired shape and then heated, the shaped body produced in this manner in an oxygen containing atmosphere to a temperature between 200 ° C and 33O ⁰ C , based on a temperature rise of 0.1 to 3 ° C / min. 40