JPS58154791A - Manufacture of pitch for high-strength, high-modulus carbon fiber - Google Patents

Abstract

PURPOSE:To highly efficiently manufacture the titled pitch at a low cost, by melting and mixing a petroleum pitch and an added specified org. compd., and cooling the mixture to separate an inorg. solid in the pitch together with the org. compd. followed by filtering. CONSTITUTION:To a petroleum pitch (A) is added an org. compd. (B) such as phthalic anhydride insoluble in the component A and having softening point higher than that of the component A and <=420 deg.C boiling point at a temp. lower than the softening point of said org. compd. and they are molten and mixed by heating to a temp. higher than the softening point of the component B. An org. solid material in the component A and the component B are separated by cooling the resulting mixture to a temp. lower than the softening point of the component B, and filtered, removing the inorg. solid material in the component A. Then the component B is added to the filtrate and the inorg. solid material in the component A is removed by repeating the above described operation. The obtd. pitch is heated with agitation to 350-450 deg.C under normal or raised pressure in a non-oxidizing gas stream.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of raw materials for high-strength, high-modulus carbon fibers, and provides a method for producing high-strength, high-modulus carbon fibers suitable as raw materials for composite materials at low cost and with high efficiency. The purpose is to provide.

More specifically, the present invention aims at converting petroleum pitch, a residual carbon substance produced by thermal catalytic cracking (FCC) of vacuum gas oil or thermal cracking of naphtha, into a non-oxidizing material at a heating temperature of 350°C to 450°C. An organic compound that is added to petroleum-based pitch as a raw material in advance to produce pitch containing mesophase pitch (which can be easily measured as quinoline dissolved content using a polarizing microscope and a quinoline dissolution test) by heat treatment with stirring under a stream of air. #r at a temperature below the softening point of
It has a softening point higher than the softening point of the raw material petroleum pitch.

An organic compound having physical properties with a boiling point of 420°C or less is added to petroleum-based pitch, then the mixture is heated above the softening point of the added organic compound to thoroughly dissolve and mix, and then cooled to below the softening point of the added organic compound. This invention relates to a method for producing pitch suitable as a raw material for high-strength, high-elastic carbon fibers by precipitating inorganic solids mixed in the raw material together with added shoulder substances and filtering the mixture at a temperature below the softening point of the added organic compound. .

As a result of the rapid growth of the aircraft, automobile, and other transportation equipment manufacturing industries in recent years, the materials required for these are combinations of special substances that have superior physical properties and can exhibit unique properties. There has been an increasing demand for materials, and there is a strong demand for materials that have particularly high strength and elasticity, and at the same time are lightweight and inexpensive. However, with the current technology, it is not possible to stably supply such materials in large quantities.

Therefore, in order to meet this demand, research on the production of composite eyelid materials (reinforced resins) is being actively conducted.High-strength, high-modulus carbon fibers are one of the most promising materials for use in 3° reinforced resins. This material appeared at the beginning of the rapid growth of the aforementioned industry, and when this carbon fiber is combined with a resin, it produces a reinforced resin that exhibits properties that are completely unparalleled. I can do it. Unfortunately, however, the high-strength, high-elasticity carbon fibers used for reinforced resins are currently extremely expensive, so even though the reinforced resins that use them exhibit extremely remarkable properties, the demand for them has not been fully exploited. .

It is a well-known fact that currently available raw materials for high-strength, high-modulus carbon fibers are mainly polyacrylonitrile fibers manufactured by special manufacturing methods.

This polyacrylonitrile fiber is not only expensive as a carbon fiber precursor, but also the yield of carbon fiber from this precursor is extremely poor at 45'J or less.

This complicates and enlarges the processing steps for producing carbon fibers with excellent physical properties, thereby increasing the cost of producing the final carbon fiber product.

As one method for producing high-strength, high-modulus carbon fibers at low cost, a method for producing them from pitch containing mesophase pitch is described in U.S. Patent Application No. 338,147. It is a well-known fact that it is an extremely excellent raw material for high modulus carbon fibers.

However, if petroleum pitch is a by-product of the catalytic thermal decomposition of vacuum gas oil, the catalyst's minute non-Ii
! It contains some solid matter. Furthermore, in the case of by-products produced by high-temperature thermal decomposition of naphtha, the reactor material often peels off due to the high temperature of VCFi, and this is mixed into petroleum-based pitch as minute solids. In a known method, petroleum pitch containing inorganic solids is heat-treated with stirring under an inert gas at a predetermined heating temperature without pre-treatment to produce pitch containing mesophase pitch. Pitch was melt-spun, made infusible, and then carbonized to produce long carbon fibers.

The inventor of this application has discovered that the inorganic solids mixed in the petroleum-based pitch create voids in the carbon fibers, and for this and other reasons, have an extremely large effect on the strength of the carbon fibers. Based on this knowledge, it is difficult to dissolve in petroleum pitch at a temperature below the softening point of the organic compound added to petroleum pitch, but it has a softening point above the softening point of petroleum pitch.

An organic compound having physical properties with a boiling point of 420°C or less is added to petroleum-based pitch, and the mixture is heated above the softening point of the added organic compound to dissolve and mix thoroughly. After 90 minutes, the mixture is cooled to below the softening point of the added organic compound and added. When organic compounds are precipitated into crystals, 1. The inorganic solids mixed in the petroleum-based pitch act as nuclei for crystal formation of the added organic compound; 1. The inorganic solids mixed in the petroleum-based pitch act as nuclei for crystal formation Precipitates together with organic compounds. The crystals of the added organic compound, which precipitate together with the inorganic solids at a temperature below the softening point of the added organic compound, are separated by filtration at a temperature below the softening point of the added organic compound, and the filtrate is extracted with petroleum pitch. It has been found that pitch containing meso-7Aze pitch can be diced by heat treatment with stirring in a stream of non-oxidizing gas at a temperature of 350° C. to 450° C. under normal pressure or increased pressure.

According to the above method, mesophase pitch free of inorganic isomorphs was separated, melt-spun, infusible, and then carbonized to produce high-strength, high-elastic carbon fibers.

A filter is used as a means to remove extremely fine inorganic solids mixed in petroleum pitch. As long as a wire mesh sieve or one-cloth filter is used as a filter, it is impossible to remove inorganic solids.

Means are needed to remove very fine solids by other means.

Use a filter to reduce inorganic solids (ash content) to 0.113
Attempts were made to remove ash from petroleum-based pitch (initial distillation 242°C → final trade 560°C or less), which is the residual carbon material from thermal catalytic cracking (YCC) of vacuum gas oil containing 6%, using the wire mesh shown below. −
It is impossible to remove fine solids that pass through the eyes.

Filtration test It was found that the extremely fine inorganic solids that pass through the wire mesh sieve are also the cause of voids (empty Wl) mixed in the carbon fiber, and it is possible to more completely remove inorganic solids in a more rational and efficient manner. As a result of research into methods for effective removal, two methods of the present invention were completed. That is, the method of the present invention uses a compound that is sparingly soluble in petroleum pitch at a temperature below the softening point of the organic compound added to the petroleum pitch as a raw material, has a softening point higher than the softening point of petroleum pitch, and has a boiling point of 420.
An organic compound with physical properties below ℃ is added to the raw material.

After that, this is heated above the softening point of the additive organic compound to dissolve and mix well, and this mixed solution is further cooled below the softening point of the additive, and when the added organic compound is precipitated as a crystal, it is mixed in the raw material. The effect is exerted as a nucleus of crystals from which inorganic solids precipitate.

The inorganic solids and the added organic compound are precipitated and separated by filtration at a temperature below the softening point of the added organic compound.

This method removes inorganic solids more completely from petroleum-based pitch as a raw material, and uses the pitch for producing raw material for high-strength, high-elastic carbon fibers.

To explain this in more detail, it is poorly soluble in petroleum pitch at a temperature below the softening point of the organic compound added to the petroleum pitch raw material, has a softening point above the softening point of the raw material, and has a boiling point of 420°C or below. There are many organic compounds that have physical properties, but they have good crystallinity.

Pure compounds are easier to handle than mixtures, and considering the operation of heating and dissolving and mixing, aromatic hydroxy acids, aromatic oxides, aromatic halogen compounds with a softening point of 40°C or higher,
Examples include paraffin wax, and commonly used organic compounds include phthalic anhydride, naphthol, and chlornaphthalene. Furthermore, since there are differences in the size of the fine inorganic solid particles mixed in the raw materials, when the added organic matter is precipitated in the form of crystals in petroleum-based pitch, the crystallization rate and the size of the formed crystals will vary. In order to remove the inorganic solids mixed in the petroleum pitch more completely, we used a bonito-type filter in advance. By filtering,
The size of the inorganic solid particles is made uniform to the extent that they can pass through a sieve, and the crystallization speed of the added organic compound and the size of the crystals formed are made as uniform as possible. It is also effective to ensure complete removal of objects.

The petroleum pitch from which the inorganic solids mixed in the petroleum pitch have been removed by the method of the present invention as described above is heated at 350°C.
Another aspect of the present invention is to produce a pitch containing mesophase pitch by stirring under a stream of non-oxidizing gas at a temperature of 450°C to 450° C. under normal pressure or increased pressure, and then separating the mesophase pitch from the pitch. The mesophase pitch thus obtained can be melt-spun, infusible, and then carbonized to produce long-fiber carbon fibers with excellent physical properties, high strength, and high elasticity. .

Hydrocarbons with a small number of carbon atoms such as methane, ethane, and propane can be used as non-oxidizing gases.

The naphtha fraction has a low boiling point and does not become heavy, and the most economical gas is dry gas (mainly a mixed gas of hydrocarbons with a small number of carbon atoms) produced as a by-product when heat treating raw materials. I can do it.

Example 1 Petroleum-based pitch (initial distillation 242°C → final distillation 560°C or less) of residual carbon material from thermal catalytic cracking (YCC) of vacuum gas oil containing 0.1136% of inorganic solids (ash content) K anhydrous phthanol Add 0.4% (by weight) of acid, heat to about 150°C, stir well to dissolve, and slowly cool to 4a°C to grow crystals of phthanolic anhydride as an additive. The filtrate was distilled under reduced pressure to reduce the initial distillation temperature from 404°C to the final distillation temperature at 560°C.
A precursor pitch was produced by heating the fraction at 400°C for 2 hours using non-oxidizing gasification.

Precursor yield 54-1 Precursor softening point (R4B phase) 6
This precursor pitch was treated at 7°C under the heat treatment conditions of the experiment number below.

Table 1 Results of normal pressure heat treatment A pitch containing mesophase pitch was obtained by treatment under the heating conditions of experiment number (1), from which meso pitch was separated, and the meso pitch was spun under the following spinning conditions.

After infusibility and carbonization, the carbon fibers were cut out and their quality was tested using the filament test method.

Spinning conditions: Temperature: 320°C Spinning hole diameter: 0.3!11/II Spinning speed: 22 Q m/l1lin Infusibility conditions: Yield of infusible fibers (in air): 10 mm, 6
-〇℃→280℃ Temperature increase rate 5℃/min Hold at 280℃ for 20 minutes Carbonization conditions: (in argon gas) #! Yield of elementary fiber 8
6.2chi 0℃ → 1.500℃ (temperature increase 10℃/min).

After 1,500℃ → 500℃ (cooling at 10℃/min)・Things from untreated pitch 1 The method of the present invention was not applied, but untreated pitch was used as the raw material and C was subjected to the same heat treatment.

There are fibers produced under the same spinning and carbonization conditions.

Example 2 The petroleum pitch of Example 1 was filtered using the 0.2 μ sieve of the above-mentioned filtration test, and β-chlornaphthalene (softening point 56°C) (0.2 tlkC weight) was added to the filtrate. The mixture was heated to about 80°C, stirred well to dissolve, and then slowly cooled to 40°C to grow crystals of chlornaphthalene, an additive, which were filtered off at 40°C.

The filtrate was distilled under reduced pressure, and the fraction with an initial distillation of 404°C and a final distillation of 560°C or higher was heat-treated at 400°C for 2 hours under non-oxidizing gas to produce a precursor pitch.

Precursor yield 54 - Precursor softening point (RAB equivalent) 67
℃ This precursor pitch was treated under the heating conditions of Experiment No. (2) in Table 1 above to obtain pitch containing mesophase pitch, from which men pitch was separated.

This was spun under the spinning conditions of Example 1, and the raw yarn was made infusible and carbonized under the same conditions as Example 1 to produce carbon fibers, and the quality of the fibers was tested using the filament test method.

Carbon fiber strength test results: Stamp 1 March 1939 2SB,
, ------, -j Director General of the Patent Office Shima 1) Mr. Haruki (Mr. Chief Adjudicator of the Patent Office) (Mr. Examiner of the Patent Office) 1. Indication of the case Showa b
Patent Application No.-322J'/No. 2, Title of Invention
High-strength, high-elastic carbon - Manufacturing method for miscellaneous pitch 3, relationship with the amended case Patent applicant address: Mr. 2, 5-1B Koenji Minami, Suginami-ku, Tokyo
Name Shozo Watabe 4, Agent Address 2-8 Shinjuku, Shinjuku-ku, Tokyo 160
No. 1 Shinjuku Seven Building 608 Room 5, Date of amendment order Voluntary amendment 6, Number of inventions increased by amendment No increase 7, Subject of amendment Detailed explanation of the invention in the specification Section 8, Contents of amendment attached Lines 11 to 14 of the negative line ``This invention - the strength of...'' is changed to ``The inventor Fi, as a result of various studies, found that the inorganic material mixed in the above petroleum-based pitch The solid state changes the strength and modulus of elasticity Kl to 1 property of the carbon trajectory.

In the 3rd to 2nd lines from the bottom of page 8, "Causes voids (1ll of voids) mixed in carbon fibers" is changed to "j that has a large influence on the physical properties 4IK strength and elastic modulus of carbon III fibers."

Page 12, lines 6 to 7, "Non-oxidizing gasification of fractions at 560°C or higher" is changed to "560
℃ or less under non-oxidizing gas.

Page 14, line 12 Change "distillate above" to "distillate below".

a. Procedural Amendment 1 Stamp 1 August 1, 1930 - H-----' Commissioner of the Patent Office Mr. Kazuo Wakasugi (Mr. Patent Office Chief Adjudicator) (Mr. Patent Office Examiner) ) 1.Display of the incident Showa b
Patent Application No. 3, 81, No. 3, 2013, Relationship with the Amendment Case Patent Applicant Address: Mr. 2, 6-18 Koenji Minami, Suginami-ku, Tokyo
Name A! 】Hi Ni
4. Agent address: 2-8 Shinjuku, Shinjuku-ku, Tokyo 160
No. 1 Shinjuku Seven Building Room 608 (1) The claims in the specification are changed to the following.

(1) An organic compound that is sparingly soluble in petroleum pitch at a temperature below the softening point of the organic compound added to petroleum pitch, has a softening point above the softening point of petroleum pitch, and has physical properties with a boiling point of 420°C or below. is added to petroleum-based pitch, the mixture is heated above the softening point of the added organic compound, thoroughly dissolved and mixed, and then cooled below the softening point of the added organic compound to form petroleum-based pitch P.
The inorganic solids mixed in the petroleum pitch are precipitated together with the added organic compound, and separated in a furnace at a temperature below the softening point of the added organic compound to remove the inorganic solids mixed in the petroleum pitch. The mixed inorganic solids are passed through a filter, and the above-mentioned organic compound is added to the F*,
The resulting mixture is heated above the softening point of the added organic compound to dissolve and mix well, and then cooled below the softening point of the added organic compound to remove inorganic solids still present in the F solution together with the added organic compound. A method of removing inorganic solids mixed in petroleum pitch by precipitating and separating in a furnace at a temperature below the softening point of the added organic compound.

(2) The above-mentioned organic compound is added to the inorganic solids mixed in the petroleum-based pitch, and the above-mentioned process 111 is carried out.

The removed petroleum pitch is heated to 31SO℃ to 4! A method for producing mesophase-containing pitch, which is a raw material for high-strength and high-elastic longitudinal fibers, by heating it under normal pressure or increased pressure at a temperature of SO° C. with stirring under a stream of non-oxidizing gas.

(2) The following amendments will be made in the detailed description of the invention section of the specification.

(1) 3jl 10th line from the top Change "-zupituchi (biased)" to "-zu (biased)."

(1st line from the bottom of page 15 “-Zubitschi wo meeting” Change it to "-".

(2)) 5th line from you Change "Includes -Zbit" to "Includes -Z".

-8th line from 6 purchase Change "Includes -Zbit" to "Includes -Z".

(v) 10th line from directly below 6 Between “Ministry” and “above °” Insert "results of various studies".

611) 63i From the 9th line from the bottom to the 1st line from the bottom, there are voids in the carbon fibers, but for this and other reasons, the strength of the longitudinal fibers is Change the physical properties of the fiber to % strength and elastic modulus.

& Yufu 6th line from the bottom 1. Change "Zbitchi to Minutes" to "Rss to Minutes."

(Hata 8j [From the third line from the bottom to the second line from the bottom, "Causes voids present in carbon fiber"]
Carbon - has a large influence on the strength and elastic modulus of the physical properties 41 of cones.''

(IX) 1st line from 11 purchase Change "Includes -Zbit" to "Includes -Z".

(→ 6th line from directly above 11 Change "-Zubitschi included" to "-Z included JKI."

1st line from 6$11 purchase Change "-zu pitch na inclusion" to "-zu wo writing."

@ 5th line from 12 purchase Change "560℃ or higher" to 1560℃ or lower.

6dl) lft 6th line from the top Change "by gasification" to "j" under r gas.

(XIV) In column 3 of Table 1 on page 12, replace Yariyagas i o, e I O061J with “I
I? Change to Yaryagasu 16161J. -W
"Carrier gas" in the first line from the bottom of page XZ is "Carrier gas methane gas (1) / Raw material C-) x (
minutes)”.

kVl) 13 Purchase from the first line to the second line from the top "-
Change "Zupitzchi Contains" to "-ZZ Contains".

6411Dll 2nd row from the top Change "Menpitch" to "Mesophase".

6@11114)j 9th line from the bottom Change "more than" to "less than".

(XIV) Page 14, 4th line from the bottom

Claims (2)

[Claims] (1) An organic compound that is poorly soluble in petroleum pitch at a temperature below the softening point of the organic compound to be added to petroleum pitch, has a softening point above the softening point of petroleum pitch, and has physical properties with a boiling point of 420°C or below. The compound is added to petroleum-based pitch, the mixture is heated above the softening point of the added organic compound to dissolve and mix well, and then cooled below the softening point of the added organic compound to form the inorganic solids mixed in the petroleum-based pitch. rc with added organic compounds
Let it precipitate. Separate at a temperature below the softening point of the added organic compound. The inorganic solids mixed in the petroleum-based pitch are removed, or the inorganic isomorphic substances mixed in the petroleum-based pitch are waxed through a filter, and the above-mentioned organic compound is added to the first liquid. The resulting mixture is heated above the softening point of the added organic compound to dissolve and mix well, and then cooled below the softening point of the added organic compound to remove any inorganic solids still present in the filtrate. A method for removing inorganic isomorphic substances mixed in petroleum-based pitch by precipitating it together with an added organic compound and separating it at a temperature below the softening point of the added organic compound. (2) Add the above-mentioned organic compound to the inorganic isomorphic substance mixed in the petroleum-based pitch, and perform the above-mentioned treatment. The removed petroleum pitch is heat-treated at a temperature of 350°C to 450°C under normal pressure or pressure, with stirring under a stream of non-saponifiable gas, to produce high-strength, high-elastic carbon rimming raw material. A method of producing pitch containing.