JPH04202287A - Improved method for preparing mesophase pitch - Google Patents

Abstract

PURPOSE: To obtain a mesophase pitch useful for obtaining a carbon fiber excellent in characteristics, in a method for producing a pitch product having a mesophase suitable for producing a carbon fiber, by constituting this method of a predetermined process and specifying the amt. of used oxidation reactive gas component-containing sprinkling gas.

CONSTITUTION: In the method for producing a pitch product containing 50-100 vol.% of a mesophase and suitable for producing a carbon fiber, this method is constituted of a process heating a carbonaceous pitch raw material (e.g.; petroleum distillation heavy residual fraction) to mesophase forming temp. during a period spraying sprinkling gas for a time sufficient to produce mesophase-containing pitch product and the amt. of the sprinkling gas containing a used oxidation reactive gas component (e.g.; O₂) is improved so as not only to be made sufficient to produce the same mesophase-containing pitch product within a time shorter than a time required in a case not using oxidation reactive gas but also to be made less than the amt. producing a pitch product with an m.p. of 400°C or higher.

COPYRIGHT: (C)1992,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to an improved method for producing carbonaceous pitch products containing between about 50 and 100% mesophids, which are suitable for carbon fiber production. More particularly, the present invention relates to a method of producing memphidized pitch, including pitch that enables the production of carbon fibers with enhanced properties using an oxidizing reactive sparge gas during heat treatment of memphidized precursors.

[Prior Art] Recently, there has been a large amount of patent literature, including those relating to the conversion of carbonaceous pitch raw materials to mesophiz-containing pitch. It is suitable for producing carbon fibers with favorable modulus, tension and elongation properties.

1 for Chwastiak
U.S. Patent No. 4,209, issued June 24, 980.
．． No. 500 describes the production of high grade mesophiz pitch that can be employed in the manufacture of carbon fibers. This invention is one of a series of patents relating to a method for producing mesophiz pitch suitable for producing carbon fibers. Each of these patents describes heat treatment or heat soaking of the open prime raw material, stirring the carbonaceous raw material and/or passing an inert gas through the carbonaceous raw material to produce a mesophized pitch suitable for the production of carbon fibers. It includes a wide range of things. Similar to what is described in the Kwastiak patent, the earlier U.S. Patent No. 3,976 to Lewis et al.
．． No. 729 and No. 4,017.327 include stirring the carbonaceous starting material during heat treatment. The use of inert gas during heat treatment is suitable for pine henry (McHe)
No. 3,974,264 and US Pat. No. 4,026,788 to NrY). Stirring or mixing the starting materials while sparging with an inert gas is also represented in the Pine-Henry patent.

The Chwastiak patent describes the prior art, and the above-mentioned Lewis (1,
Ewis et al.'s patent is similar, and the Pine Henry patent is also mentioned above. These disclosures are summarized in Kwastiak, column 1, line 13 to column 2, line 50. Lewis
Suggestions for promoting mesophize formation are very limited, according to Is) et al. and McHenry, whose pitch products are separated into a two-phase system followed by It is packed by spinning.

Kwastiak proposes a mesophyz pitch production method that results in a single phase product. According to Kwastiak, the process required for both agitation and inert gas sparging is improved by passing inert gas through the pitch at a rate of at least 4 standard cubic feet per hour (SCFH) per pitch bond. be done. In the figure, heat treatment is required for 44 hours. Therefore, it would be highly beneficial to provide a process that does not require such a high proportion of flow of inert gas and can be completed in less time without deleterious effects on the pitch product.

Published German patent application number box 3305-055-A
(Nippon Oil Co., Ltd.) describes initial heat treatment of pitch material to 370 to 420° C. or pressure reduction in a flow of inert gas for 5 to 20 hours under air. An oxidant gas such as air or oxygen is then passed through the pitch at a flow rate of 10 minutes to 2 hours at 200 to 350° C. and 1 atmosphere at 1.0 to 3.58 CFH. No increase in mesophiz content has been reported as a result of the oxidant gas separation process.

Koppers Co., Ltd. DT222
1707-Q and DT2357477 patent applications, in which the starting materials are first reacted with oxygen, evacuated,
The production of isotropic carbon fibers excluding non-oxidized low boiling tin components is disclosed.

The present invention provides a method for shortening the heating process even more quickly than would be required without the reactive gas component if the gas or mixture gas containing an effective but not excessive amount of the oxidizing reactive gas is applied to the heated laparotomy prime stock storage. 50 to 100% by volume in hours
A pitch product with mesophise content, determined by visible anisotropy, results. The product yields fibers that are often substantially 100% mesophized, have melting points suitable for fiber spinning, and have improved elasticity and elongation properties.

The use of oxidizing components in the sparge gas stream in this manner is important so that the reactive components of the sparge gas promote conversion to mesophizes without the production of unacceptable high-melting pitch products. Control is important. At the same time, the sparge gas removes volatile components from the feedstock that are known to be undesirable in mesophiz pitch products used in the production of carbon fibers. In addition, the use of a controlled amount of sparge gas with oxidizing components further influences the chemical and physical properties of the Sophiz pitch product. The resulting carbon fiber spuns are characterized by outstanding elastic modulus and high tensile strength as well as improved elongation rates.

As used herein, the term "pitch" refers to petroleum pitch, natural asphalt and heavy oil obtained as a by-product of the i-fusa grinding industry, the high carbon content obtained from petroleum asphalt, and the nature of pitch obtained as a by-product of various industrial production processes. means any other substance that has

The term "petroleum pitch" refers to the residual carbonaceous feedstock obtained by thermal and petroleum distillation catalyst grinding.

In general, pitches containing a high percentage of aromatics are suitable for carrying out the present invention.

Approximately 75% to 9 as determined by nuclear magnetic resonance spectroscopy
Carbonaceous pitch containing 0% aromatic carbon is particularly useful in the process of the present invention.

Therefore, the higher the boiling point, higher aromatic content of such pitches, or the greater the conversion pressure to such pitches, the more beneficial it is.

On a weight basis, useful pitches have about 88 to about 93% and about 7% to about 5% hydrogen. Few elements other than carbon and hydrogen, such as sulfur and nitrogen, are commonly present in such pitches. It is important that these other elements do not exceed 4% by weight based on the pitch. These useful pitches also typically have an average molecular weight of 200 to 1,0
00.

These petroleum pitches meeting subsequent requirements are the preferred initial materials for the practice of this invention. Thus, the carbonaceous residue of the crude oil, especially for example about 90% by volume and more, during heat treatment at elevated temperatures, for example from 350°C to 4.
It is clear that an isotropic carbonaceous petroleum pitch feedstock known to form large amounts of mesophizes in the 50°C range is a preferred starting material for the practice of the invention.

In general, any petroleum or coal derived heavy hydrocarbon fraction will contain aromatic distillate residues which will be turned into carbonaceous materials in the process of the present invention. Petroleum pitch type materials are preferred.

Preferred sparges consisting of inert ingredients are gases or mixtures of gases. It does not react with the material at heat treatment temperatures.

The oxidizing reactive gas or mixture of gases is then present in an effective amount to form mesophise and less than to produce mesophise pitch having a melting point of about 400°C. and preferably less than that to produce Memphis pitch having a melting point of about 360°C. Mesophyz pisothi, which has a melting point of about 360°C, is difficult to spin because it forms coke, and it is substantially difficult to spin because it melts at about 400°C.

A particularly preferred sparge gas is 0.1 to 2.0 relative to oxygen.
Contains % nitrogen by volume.

Gases other than oxygen such as ozone, hydrogen peroxide, nitrogen dioxide, formic acid vapor and hydrogen chloride vapor may be used as oxidizing components. The amount of the inert gas component is 0.
1 to 2.0% by volume of oxygen must be selected to have the same oxygen reactivity for the mesophize-forming material as supplied using oxygen.

The inert scum component in the sparge gas is a scum or gas mixture that does not react with the raw material under heating. The illustrated inert gases are nitrogen, argon, xenon, helium, methane, hydrocarbon fluids, water vapor, and mixtures thereof. In general, any gas stream or mixture of gas streams having suitable oxidizing components such that reaction with the material or molecules within the material will occur will be employed. However, the reactive gas used for sparging is effective in reacting with the material directly or indirectly, i.e. catalytically, so that it can be spun into high quality carbon fibers with increased mesophize content. .

The sparging gas rate is at least 0.1S per pound of material.
CFH, preferably 0. ] to 2O8CFH.

Spraying is generally carried out at atmospheric pressure or under slightly elevated pressure, ie about 1 to 3 atmospheres.

The sparging time can vary widely depending on the material, gas-to-material ratio. For the first purpose, a heat treatment or heating step is often carried out for a duration ranging from 2 to 100 hours. However, in some cases oxidizing components are added to shorten the time.

As mentioned above, an important feature of the present invention is that 50 to 100
The method is to use a controlled sparge gas containing oxidizing components during heating of carbonaceous raw materials to form a pitch containing % Mesophize by volume. Thus, the sparge gas of the present invention promotes the formation of mesophizes from isotropic materials, ie the sparge gas simultaneously carries away undesirable volatile components while increasing the amount of mesophizes within a short period of time to the desired range. In addition, the produced mesofyz has already been converted into carbon fiber with improved properties compared to mesofyz produced under similar conditions but without the use of an oxidizing reactive sparge gas component.

The mesophiz pitch product of the present invention is spun into continuous anisotropic carbon fibers following separate heat curing and carbonization steps in a conventional melt spinning-like procedure.

Example 1 A series of Mesofize pitches are made from a heavy residual fraction of heavy oil from an FCC unit (900'F+ fraction) by heat treatment at 385°C and sparging with a mixture of oxygen and nitrogen gas at atmospheric pressure. The heavy residual fraction is enclosed in a glass reactor with a capacity of approximately 340 ml during the heat treatment step. The reactor charged sparge gas is controlled at 1.755 CFH throughout the heating process. The oxygen concentration of the spray gas is between 0.01 and 2.
It varies within the range of 0% by volume. The melting point and mesophiz content of the product pitch are determined with a hot stage microscope. Table 1 shows the yield and properties of Mesophiz pitch.

As the amount of oxygen in the sparge gas increases, the time required to produce 100% mesophiz pitch decreases, indicating an increase in the yield of mesophiz pitch product. Mesofiz pitches A, B, C, D and E were spun into fiber filaments with single hole spun projections. The as-spun fiber filament was placed in an oven and heated in air from room temperature to 350°C at a rate of 4°C per minute, heated for 32 minutes at 350°C, and heated to 195°C.
Carbonization is carried out with argon at a temperature of 0°C.

The carbonized fiber is tested as a 2.54 mark gauge length monofilament with a 10% elongation rate per minute.

Table 2 shows the properties of the carbonized fibers produced.

Table 2 Characteristics of manufactured carbon fibers Tensile strength Elasticity Elongation bibuti xlo 3 psig
xlO” ps Yu Ki Sample A 329 45
0. 68B 3
00 46 0. 6
7C40537 93 D 357 39
0.84E 359 36 屹83 From the results in Table 2, the fibers produced from Mesofize pitch prepared by adding a controlled amount of oxygen to the nitrogen sparging gas were found to contain high purity nitrogen (<Q, 01% by volume) as the sparging gas. It has a higher elongation rate than those made using oxygen).

Example 2 A series of Memphis pitches is made from a heavy residual fraction of heavy oil from an FCC unit. The reactor system and operating conditions for heating are essentially the same as in Example 1 above. In addition to gas sparging through the reactor charge, 0.00
High purity nitrogen containing less than 1% oxygen by volume is continuously
A rate of 1.75 SCFH is sprayed onto the reactor through the space under the reactor roof. This blowing process surrounded the top of the reactor with inert gas. The properties of the produced Mesophiz pitch are shown in Table 3.

The mesophiz pitch produced above is spun into stable fibers similar to Example 1. The fibers are carbonized at 100°C. Table 4 shows the properties of the produced carbon fibers.

Table 4 Characteristics of manufactured carbon fibers Mesophyz Tension Molecule Elongation pitch xlo 3 psig
xlo 6 psi % Sample A-316340,92 B-329241,17 C-401500,73 D-397321,16 The results in Table 4 demonstrate that the elongation rate enhancement by adding sparge gas with a controlled amount of oxygen It is shown.

Referring to Figure 1, it can be seen that when a sparge gas with a controlled amount of oxygen is employed as the oxidizing component, the time required for the raw material to convert into mesophizic pitch suitable for carbon fiber production can be reduced. is important. However, the reason for this is not well understood. It is believed that this is because the reactive or oxidizing components in the sparge gas react with the aromatic molecules of the raw material, forming certain free radicals that lead to an increased degree of polymerization via free radical chains.

In the manufacturing method of the present invention, various changes and modifications can be made without departing from the purpose or scope of the present invention. The various embodiments are not limited to those shown herein.

[Brief explanation of the drawing]

FIG. 1 is a graph of heat soak time versus oxygen content in sparging using a heavy oil feedstock of fluid contact bone (FCC) under fixed set conditions.

Claims (15)

[Claims] (1) In a method for producing a pitch product having a mesophize content of 50 to 100% by volume and a mesophize suitable for the production of carbon fiber, the sparge gas is used for a sufficient period of time for the process to produce the mesophize-containing pitch product. heating the carbonaceous pitch raw material at a mesofize-forming temperature during spraying, the amount of spray gas containing the oxidizing reactive gas component being (a) in a shorter period of time than would be required without the use of the oxidizing reactive gas; An improved method for the production of mesophise pitch, characterized in that the amount is sufficient to produce said mesophise content and (b) less than that to produce a pitch product having a melting point of 400° C. or higher. (2) The method according to claim 1, wherein the oxidation-reactive gaseous component is selected from the group consisting of oxygen, ozone, hydrogen peroxide, formic acid vapor, hydrogen chloride vapor, and mixtures thereof. 3. A process as claimed in claim 1, in which the sparging gas comprises, in particular, 0.1 to 2.0% by volume oxygen and the remainder inert gas. 4. The method of claim 1, wherein the pitch product is substantially 100% mesophized pitch with a melting point not higher than 360°C. (5) the feedstock is heated at a temperature range of about 350°C to 450°C for 2 to 100 hours, the remainder being inert and consisting essentially of 0.1 to 2.0% oxygen by volume, and the sparge gas being 2. The method of claim 1, wherein 0.1 to 20 SCFH is introduced per pound of raw material. (6) heating a carbonaceous feedstock at a temperature in the range of about 350° C. to 450° C. while blowing a sparge gas at a rate of at least 0.1 SCFH per pound of feedstock to produce Mesophiz; the sparge gas is oxidatively reactive; a gas component in an amount effective to promote the formation of the mesophizes;
A method for producing anisotropic pitch having a mesophize content of 100% and suitable for producing carbon fiber. (7) The manufacturing method according to claim 6, wherein the raw material is pitch. 8. The method of claim 6, wherein the anisotropic pitch product contains 90 to 100% mesophise. (9) The production method according to claim 6, wherein the dispersion gas contains 0.1 to 2.0% by volume of oxygen. (10) The sparge gas contains substantially oxidation-reactive gaseous components and an inert gas, including nitrogen, argon, xenon,
The manufacturing method according to claim 6, wherein the gas is selected from the group consisting of helium, methane, hydrocarbon flue gas, steam, and mixtures thereof. (11) The manufacturing method according to claim 10, wherein the inert gas is nitrogen. (12) The sparge gas rate range is approximately 0.
11. The manufacturing method according to claim 10, wherein the amount is 1 to 20 SCFH. (13) A process in which a sparge gas is passed through a carbonaceous raw material and heated at an elevated temperature to produce mesofize, which is suitable for the production of carbon fibers having 50 to 100% mesofize and improved properties. The method is characterized by utilizing a sparge gas containing an oxidation-reactive component in an effective amount to produce an oriented pitch product. (14) The manufacturing method according to claim 13, wherein the oxidation-reactive component is oxygen. (15) The manufacturing method according to claim 14, wherein the remainder of the dispersion gas is nitrogen.