JP2016074995A - Method for producing pitch for carbon fiber and pitch for carbon fiber obtained thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing pitch for carbon fiber, which can improve oxidation stability and tensile strength through radical crosslinking of each molecule in a petroleum-process residual oil by using a prescribed radical source, and which lowers a content of quinoline insoluble (QI) matter, and to provide pitch for carbon fiber produced by the method.SOLUTION: The method for producing pitch for carbon fiber, comprising: charging a peroxide-based compound and ozone into a petroleum-process residual oil; and reacting these by heat-treating the same.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pitch for carbon fiber, and more particularly to a method for producing a pitch for carbon fiber having a high softening point through radical crosslinking and a pitch for carbon fiber produced thereby.

  Carbon fibers are classified into PAN (Polyacrylonitrile), cellulose, pitch, and phenol resin types depending on the raw material. Among these, pitch-based carbon fibers are liquid crystal (Mesophase) pitch systems depending on the type of pitch that is a precursor. It can be roughly divided into carbon fibers and isotropic pitch-based carbon fibers.

  The liquid crystal pitch-based carbon fiber is manufactured using a liquid crystal pitch that is optically anisotropic as a precursor, and the isotropic pitch-based carbon fiber is optically isotropic as a precursor. Manufactured using a characteristic pitch. Regarding the mechanical properties of carbon fibers, liquid crystal pitch-based carbon fibers generally exhibit high strength and high elasticity, while isotropic pitch-based carbon fibers exhibit general-purpose physical properties of low strength and low elasticity.

  However, since the liquid crystal pitch-based carbon fiber is applied to a limited range such as an ultra-high temperature material, it is further required to produce an isotropic precursor pitch for producing a general-purpose carbon fiber. Such a general-purpose carbon fiber is low in price, but requires high strength and high elasticity. Therefore, in order to improve physical properties, research on initial raw materials and manufacturing processes is necessary.

  Pitch-based carbon fibers are melted and radiated into fiber by using a radiator to pitch the precursor pitch, and then the fiberized pitch is oxidized for a certain period of time in an oxidizing atmosphere in the temperature range of 150 ° C to 350 ° C. In general, after the stabilization treatment, it is produced by treatment in an inert atmosphere in a temperature range of 700 ° C. to 3000 ° C. for a predetermined time according to the use.

  At the time of carbon fiber production, the production cost of the fiber is affected by the price of the precursor pitch, the radiation of the precursor pitch, the rate of oxidation stabilization, the carbonization yield after carbonization, etc. In terms of time, it is known that an oxidation stabilization process that requires a long reaction time requires the longest time, and development of a precursor pitch excellent in oxidation stabilization performance is known as an important technique.

  As a method for producing an isotropic pitch having a softening point of 200 ° C. or higher, which is used as a raw material for the isotropic pitch-based carbon fiber, a method for removing low molecular weight components from coal-based pitch by vacuum distillation and solvent extraction, Examples thereof include a method of condensing a low molecular weight component in a raw material by simple thermal condensation to convert it into a polymer component, and a method of producing the two methods in parallel. However, such a method can produce an isotropic pitch having a relatively narrow molecular weight distribution from a raw material having a wide molecular weight distribution. There are disadvantages in terms of the homogeneity and radioactivity of the produced pitch, such as remaining components.

  Recently, research has been actively conducted on the use of petroleum refining residue, which is low in price and excellent in elastic modulus, heat and electrical conductivity, as a raw material for isotropic pitch-based carbon fibers. Of these, FCC-DO (fluidized catalytic cracking oil) and PFO (pyrolyzed fuel oil) are high aromatization and low sulfur and insoluble content, especially as petroleum target raw materials. It attracts attention as a raw material suitable for high added carbon materials such as fibers, needle coke and artificial graphite.

  Patent Document 1 (1999.02.25. Published) discloses a pitch that can be used as a precursor of carbon fiber by using a petroleum-based material as a carbon source and reacting a halogen compound and a radical initiator with the petroleum-based material. A method for producing a high softening point optically isotropic pitch is disclosed.

Republic of Korea Registered Patent Publication No. 0244912

  The object of the present invention is to improve oxidation stability and tensile strength through radical cross-linking of each molecule in petroleum process residue oil using a specific radical source, having a low quinoline insoluble (QI) content, and a high softening point. It is providing the pitch for carbon fibers manufactured by the manufacturing method of the pitch for carbon fibers, and it.

  In order to achieve the above object, a method for producing a pitch for carbon fiber according to an embodiment of the present invention is characterized in that a peroxide-based compound and ozone are charged into petroleum process residue oil, and are reacted by heat treatment. .

  Moreover, the pitch for carbon fiber which concerns on one Example of this invention for achieving the said objective has the high softening point of 250 to 320 degreeC, the weight average molecular weight of 1,000-10,000, and oxygen of 106% or less. It is characterized by having a degree of saturation.

  The pitch for carbon fiber according to another embodiment of the present invention for achieving the above object is characterized in that the quinoline insoluble (QI) content is 5% by weight or less.

  The carbon fiber pitch manufacturing method according to the present invention has the following effects.

  First, the present invention provides a novel pitch production method by generating hydroxyl radicals (.OH) using peroxide compounds and ozone as radical sources.

  Second, by increasing the molecular weight through radical crosslinking, the oxidation stabilization time can be shortened by reducing the oxygen saturation of each pitch molecule.

  Third, each condensed aromatic composed of σ-bonds is oriented in the fiber direction through radical crosslinking, whereby the tensile properties of the carbon fiber can be improved.

  Fourth, asphaltene aggregation due to high-temperature polymerization can be prevented, formation of infusible components due to oxidation of raw materials can be suppressed, and the applicability of fibers is high.

Fifth, water (H ₂ O) and alcohol are generated as by-products of radical polymerization reaction using a peroxide compound and ozone, so that an environmentally friendly process can be constructed.

  Sixth, a separate catalyst is not required, and a relatively high yield can be obtained at a low temperature of 100 ° C to 200 ° C.

  According to the present invention, it is possible to provide a pitch for carbon fiber that has a high softening point and high strength but is excellent in oxidative stability and oxidative infusibilities and has a low quinoline insoluble (QI) content.

3 is a graph showing a TG (Thermogravimetric) curve in the air with respect to the pitches obtained in Example 3 and Comparative Example 1. FIG. 3 is a scanning electron microscope (SEM) photograph of carbon fibers manufactured using pitches manufactured according to Example 3 and Comparative Example 1. FIG.

  Advantages and features of the present invention and methods of achieving them will be apparent with reference to the embodiments described in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. However, this embodiment is provided in order to complete the disclosure of the present invention and to fully inform the person of ordinary skill in the technical field to which the present invention belongs the scope of the invention. They are only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

  Hereinafter, the manufacturing method of the pitch for carbon fibers which concerns on this invention is demonstrated in detail.

  The carbon fiber pitch manufacturing method according to the embodiment of the present invention is characterized in that a petroleum compound residue oil is charged with a peroxide-based compound and ozone, and heat-treated to cause a radical polymerization reaction.

  Here, the petroleum process residue oil is a carbon source of carbon fiber pitch, and is a residue oil obtained as a by-product of the naphtha decomposition process, that is, a naphtha cracking bottom oil (NCB Oil). Is preferred.

  It is preferable that the naphtha cracking residue oil contains pyrolyzed fuel oil (PFO). The pyrolysis fuel oil (PFO) is produced at the bottom of a naphtha cracking center (NCC) and has a high degree of aromatization and a high resin content. It is suitable for the manufacturing method of carbon fiber pitch.

  The pyrolysis fuel oil (PFO) contains various aromatic hydrocarbons, and naphthalene and methylnaphthalene derivatives account for about 25% to 35%. Specific examples of the naphthalene and methylnaphthalene derivatives include ethylbenzene, 1-ethenyl-3-methylbenzene, indene, 1-ethyl-3-methylbenzene, 1-methylethylbenzene, 2-ethyl-1,3-dimethylbenzene, Propylbenzene, 1-methyl-4- (2-propenyl) -benzene, 1,1a, 6,6a-tetrahydro-cycllopropa [a] indene), 2-ethyl-1H-indene, 1-methyl-1H-indene, 4,7-di-methyl-1H-indene, 1-methyl-9H-fluorene, 1,7-dimethylnaphthalene, 2-methylindene, 4,4'-dimethylbiphenyl, naphthalene, 4-methyl-1,1 ' -Biphenyl, anthracene, 2-methylnaphthalene, 1-methylnaphthalene, etc.

  In the present invention, the petroleum process residue oil, that is, the carbon source may be one from which low boilers have been removed. Most of the low-boiling substances are volatilized and do not participate in the reaction. Therefore, the pitch yield is extremely low, and C4-C20 hydrocarbons belong to this. In the present invention, when using a carbon source from which such low-boiling substances are removed, the carbon source can be produced at a higher yield and a higher softening point pitch.

In the present invention, a peroxide compound and ozone (Ozone, O ₃ ) are radical sources, and generate hydroxyl radicals (Hydroxyl Radical, .OH) by thermal cracking.

  For example, the peroxide compound may include one or more of dicumyl peroxide (DCP), hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, and methyl ethyl ketone peroxide.

The peroxide compound is preferably charged at a ratio of 5 to 50 parts by weight with respect to 100 parts by weight of the petroleum process residue oil. The ozone may be supplied in a gas state, and may be charged under a partial pressure of 20 g / m ^{2 to} 100 g / m ² , preferably 25.8 g / m ² .

When the peroxide compound is charged at less than 5 parts by weight, or when the ozone is charged at a partial pressure of less than 20 g / m ^2, since the amount of radicals participating in the reaction is small, the required pitch Manufacturing becomes difficult.

On the other hand, when the peroxide compound is charged in an amount exceeding 50 parts by weight, or when the ozone is charged at a partial pressure exceeding 100 g / m ² , radicals are generated in large quantities, but there is no oxidation due to oxidation of the raw material. A fusing component is formed.

  The radical polymerization reaction according to the present invention will be specifically described through the following [Target reaction formula 1].

[Target reaction formula 1]

  First, in the present invention, a peroxide compound as a radical source and ozone are charged into a raw material such as petroleum process residue oil as a carbon source.

  In this process, it is more preferable that the petroleum process residue oil and the peroxide compound are charged into the reactor and mixed, and then charged into the reactor while maintaining the gaseous ozone at a constant partial pressure. Stirring can also be carried out in a state where petroleum process residue oil and a peroxide compound are mixed or ozone is charged.

  Thereafter, heat treatment is performed in a state where ozone is charged to induce a radical polymerization reaction.

  When heat treatment is performed, first, a pyrolysis reaction occurs in petroleum process residue oil, and gas and hard oil are released out of the system. At the same time, hydroxyl radicals (.OH) are generated from peroxide compounds and ozone. The

  Thereafter, each molecule in the petroleum process residue oil having an aromatic structure forms a radical crosslink by the generated hydroxyl radical (.OH), and the chain extension reaction of each molecule in each petroleum process residue oil is performed. While occurring, polycondensation polymerisation occurs. As a result, an isotropic pitch having a high-temperature softening point of 250 ° C. or higher, preferably 250 ° C. to 320 ° C. was finally synthesized, which was confirmed through Table 1 and FIGS.

  In the present invention, a condensed polycyclic aromatic group having a large number of aromatic structures is formed on the lower side of a long chain while a polycondensation reaction through radical crosslinking proceeds.

  Radical vulcanization is mainly used for cross-linking of polymers, but in the case of branched aromatics, the radical stability is higher than that of polymers, so that radical stability is higher. This is because the reaction in which is bonded to and removed from the hydrogen atom in the chain is easier.

  The present invention applies the principle of radical vulcanization described above to induce the bonding of aromatic hydrocarbons in petroleum process residue oil through hydroxyl radicals (.OH) to form linear molecular series formation pitch. The weight average molecular weight can be increased to about 1,000 to 10,000.

  On the other hand, the pitch produced in the present invention has a weight average molecular weight of about 1,000 to 10,000, which is higher than the existing ones, and a quinoline insoluble (QI) content is as low as 5% by weight or less (preferably 0%). ), And is excellent in radioactivity, and is excellent in tensile strength and modulus of carbon fiber produced therefrom.

  The increase in the pitch molecular weight provides the effect that the oxygen saturation of each pitch molecule can be reduced and the oxidation stabilization time can be shortened. As a result, it is possible to produce a precursor pitch having excellent oxidation stability. The decrease in the oxidation saturation due to the increase in the molecular weight of the pitch was confirmed through Table 1.

  In addition, each condensed polycyclic aromatic linear molecule composed of σ-bonds between aromatic compounds produced while the polycondensation reaction through radical crosslinking proceeds is oriented in the fiber direction. Therefore, when this pitch is used, physical properties such as the tensile strength of the carbon fiber can be improved. This was confirmed through Table 2.

  Here, the heat treatment is preferably performed at a temperature of 100 ° C. to 200 ° C. in order to induce a radical polymerization reaction through generation of hydroxyl radical (.OH) and radical crosslinking.

  When the heating temperature is less than 100 ° C., formation of hydroxyl radical (.OH) from the peroxide compound and ozone becomes impossible, whereas when the heating temperature exceeds 200 ° C., the chain extension reaction is terminated, Manufacturing pitches with the required molecular weight can be difficult.

  The reaction time is preferably 1 hour to 10 hours. When the reaction time is less than 1 hour, sufficient reaction is impossible, while when the reaction time exceeds 10 hours, there is a problem that solidification may occur during the reaction.

  In the above, it has been explained that the heat treatment is performed in a state where ozone is charged. However, in the sense that ozone is charged and heat treated, the heat treatment is simultaneously performed while charging (supplying) ozone. Of course, it is also included.

  As described above, the present invention does not require a separate catalyst, and is described in Table 1 through increasing the molecular weight of the pitch through radical polymerization using hydroxyl radical (.OH) at a low temperature of 100 ° C. to 200 ° C. In addition, a relatively high polymerization yield of 20% or more could be obtained.

  In addition, as shown in FIG. 2, it is possible to prevent agglomeration of asphaltenes due to high temperature polymerization, suppress formation of infusible components due to oxidation of raw materials, and have excellent oxidative infusibilities, so that the applicability of fibers is high. Have.

Furthermore, although not shown in the drawings, according to the pitch production method of the present invention, water (H ₂ O) and alcohol are generated as by-products of the radical polymerization reaction by using a peroxide compound and ozone as a radical source. Since such reaction by-products are harmless to the human body, environmentally friendly process construction is possible.

  On the other hand, in the present invention, when the petroleum process residue oil is used in a state where the low-boiling substances are not removed, a secondary heat treatment for removing the low-boiling substances by further raising the temperature of the resultant product after the reaction is further performed. You may implement.

  In this case, the secondary heat treatment temperature reached by raising the temperature of the resulting reaction-completed product is preferably 300 ° C to 400 ° C. When the secondary heat treatment temperature is less than 300 ° C., it is difficult to sufficiently remove low-boiling substances. On the other hand, when the secondary heat treatment temperature exceeds 400 ° C., lost reactants and coking due to decomposition reaction and rapid coking reaction are caused. There is a problem.

  Moreover, it is preferable that the secondary heat treatment for removing low-boiling substances is performed for 1/2 hour to 10 hours. When the secondary heat treatment time is less than ½ hour, it is impossible to sufficiently remove low-boiling substances, while when the secondary heat treatment time exceeds 10 hours, there are problems of coking and decomposition reaction.

  As described above, according to the pitch manufacturing method of the present invention, it is possible to provide a pitch for carbon fiber that has a high softening point, high strength, and the like, and is excellent in oxidation stability and oxidation infusibilities.

  Therefore, the pitch according to the present invention is used as a raw material and a precursor of high-functional carbon materials such as carbon fibers, activated carbon fibers, carbon-carbon composite binder materials, and carbon materials for lithium ion secondary battery negative electrodes. Also good.

EXAMPLES Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred examples of the present invention. However, this is presented as a preferred illustration of the present invention and should not be construed as limiting the invention in any way. The contents not described here can be sufficiently technically analogized by those skilled in this technical field, and the description thereof will be omitted.

(1) Production of pitch Examples 1 to 10
Pyrolysis fuel oil (PFO) and dicumyl peroxide (DCP) or hydrogen peroxide are charged into a reactor and mixed, and then heat-treated while charging ozone (O ₃ ) gas to carry out radical polymerization reaction. Proceeded.

After completion of the radical polymerization reaction, unreacted or low-reacted molecules were removed by passing nitrogen gas at a flow rate of 2 L / min through the resulting product over a certain period of time to obtain the pitches produced in Examples 1-10.
The reaction conditions for each example are as shown in Table 1 below.

Comparative Example 1
After the pyrolysis fuel oil (PFO) was charged into the reactor, the thermal polymerization reaction was advanced by heat treatment in a nitrogen atmosphere.

  After the thermal polymerization reaction was completed, unreacted or low-reacted molecules were removed by passing nitrogen gas at a flow rate of 2 L / min through the resulting product for 5 hours, thereby obtaining a pitch.

  The reaction conditions of the comparative example are as shown in Table 1 below.

(2) Evaluation of Physical Properties of Pitch Softening point, molecular weight, oxygen saturation, toluene insoluble (TI) content, quinoline insoluble (QI) content, beta resin (TI) obtained in Examples 1 to 10 and Comparative Example 1 -QI) The content and yield were measured and are shown in Table 1 below.

  TG (Thermogravimetric) in the air with respect to the pitches obtained in Example 3 and Comparative Example 1 was analyzed and is shown in FIG.

  Here, the yield means the degree of polymerization of the reaction.

  FIG. 1 is a graph showing a TG curve in the air with respect to the pitch obtained in Example 3 and Comparative Example 1.

Referring to Table 1 and FIG. 1, Examples 1 to 10 using any one of DCP and hydrogen peroxide and O ₃ as a radical source have physical properties targeted in terms of softening point and yield. Satisfactory, it can be seen that the oxygen saturation was significantly reduced and the yield was improved by the molecular weight significantly increased from Comparative Example 1 using the thermal polymerization reaction.

  Moreover, as a result of comparing Examples 1 to 3, it can be seen that the yield is optimized when the reaction time is 5 hours in the PFO reforming, and the molecular weight increases in proportion to the reaction time.

  As a result of comparing Examples 3, 5, and 7, it can be seen that even if the ozone concentration increases, the yield and molecular weight do not change greatly, so that it is not necessary to exceed the ozone concentration necessary for the reaction.

  Further, as a result of comparing Example 3 and Example 9, it is understood that when DCP is used, the molecular weight and the yield decrease as the heat treatment temperature increases. This is because DCP cannot sufficiently participate in the reaction because the decomposition rate is very fast at 170 ° C. because of the difference due to the decomposition rate depending on the temperature of DCP.

  Moreover, as a result of comparing Example 3 and Example 4, it can be seen that when hydrogen peroxide and ozone are present at the same time, the yield is greatly increased as compared with the case where DCP and ozone are simultaneously present.

  Moreover, as a result of comparing Examples 4, 6, and 8, hydrogen peroxide is not required to exceed the ozone concentration necessary for the reaction because the yield and molecular weight change are not large even when the ozone concentration is increased.

  Moreover, as a result of comparing Example 4 and Example 10, it can be seen that as the heat treatment temperature increases, decomposition of hydrogen peroxide is promoted and the yield increases.

  Moreover, it turns out that molecular weight increases through Examples 1-10 as the yield of a pitch increases.

In addition, referring to Table 1, Examples 1 to 10 using any one of DCP and hydrogen peroxide and O ₃ as a radical source exhibit physical properties with low quinoline insoluble (QI) content. It is understood that it is excellent.

(3) Manufacture of carbon fiber Using the pitch manufactured by the said Example 3 and the comparative example 1, the carbon fiber was manufactured through the radiation, oxidation, and carbonization processes which are a normal method.

  Then, the front and cross section of each produced carbon fiber were observed with a scanning electron microscope (SEM).

  FIG. 2 is an SEM photograph of carbon fibers manufactured using the pitches manufactured in Example 3 and Comparative Example 1.

  As shown in FIG. 2, when the pitch produced according to Example 3 that satisfies the synthesis conditions presented in the present invention is used, the spherical infusible component is hardly formed, and the finally produced carbon fiber. Was confirmed to be isotropic.

  On the other hand, when the pitch produced by Comparative Example 1 using a thermal polymerization reaction is used, the finally produced carbon fiber is also isotropic, but a large amount of spherical infusible components are formed. I was able to confirm.

(4) Tensile strength and modulus evaluation of carbon fiber Tensile strength of carbon fibers A1 to A10 using the pitch manufactured according to Example 3 and carbon fibers B1 to B10 using the pitch manufactured according to Comparative Example 1. The modulus was evaluated and the results are shown in Table 2.

  At this time, the modulus means an elastic coefficient (Young's modulus) with respect to tensile strength.

  Referring to Table 2, in the case of the carbon fiber using the pitch manufactured according to Example 3 of the present invention, both the average tensile strength and the average modulus are compared with the carbon fiber using the pitch manufactured according to Comparative Example 1. It was high, and it was confirmed that it had a high average tensile strength of 0.7416 GPa and a high modulus of average modulus of 44.0803 GPa.

  In the above, the embodiments of the present invention have been described mainly. However, this is merely an example, and various modifications and equivalents will be made by engineers having ordinary knowledge in the technical field to which the present invention belongs. It will be appreciated that other embodiments are possible. Accordingly, the true technical protection scope of the present invention should be determined by the claims set forth below.

Claims (18)

  A method for producing a pitch for carbon fiber, comprising charging a petroleum-based process residue oil with a peroxide-based compound and ozone and reacting them by heat treatment.   The peroxide compound includes at least one of dicumyl peroxide (DCP), hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, and methyl ethyl ketone peroxide. The manufacturing method of the pitch for carbon fibers described in 2.   The said heat processing is implemented at the temperature of 100 to 200 degreeC, The manufacturing method of the pitch for carbon fibers of Claim 1 characterized by the above-mentioned. The ozone, characterized in that it is charged by the partial pressure of ^{20g / m 2 ~100g / m 2} , the production method of carbon fiber for the pitch of claim 1.   The said reaction is implemented for 1 hour-10 hours, The manufacturing method of the pitch for carbon fibers of Claim 1 characterized by the above-mentioned. The carbon fiber pitch manufacturing method includes:
A thermal decomposition step in which a radical (OH) is generated from the peroxide compound and ozone by a thermal decomposition reaction;
Crosslinking and polycondensation reaction steps in which each molecule in the petroleum process residue oil forms a radical crosslinking bond through the hydroxyl radical (.OH) and causes a chain extension reaction. 6. A method for producing a pitch for carbon fiber according to any one of 5 above.   The method for producing a pitch for carbon fiber according to claim 1, wherein the petroleum process residual oil includes naphtha decomposition residual oil.   The method for producing a pitch for carbon fiber according to claim 7, wherein the naphtha cracking residue oil includes pyrolyzed fuel oil (PFO).   The carbon fiber according to claim 1, 2 or 6, wherein the peroxide compound is charged in a ratio of 5 to 50 parts by weight with respect to 100 parts by weight of the petroleum process residue oil. Pitch manufacturing method.   The method for producing a pitch for carbon fiber according to claim 1, 6 or 7, wherein the petroleum process residue oil includes a product obtained by removing low boiling point substances.   The method for producing a pitch for carbon fiber according to claim 1 or 6, further comprising a heat treatment for removing low-boiling substances by raising the temperature of the resultant product after the completion of the reaction.   The method for producing a pitch for carbon fibers according to claim 11, wherein the heat treatment for removing the low-boiling substances is performed at a temperature of 300C to 400C. The heat treatment for removing the low-boiling substances is:
It implements over 1/2 hour-10 hours, The manufacturing method of the pitch for carbon fibers of Claim 11 characterized by the above-mentioned.   A carbon fiber pitch produced according to at least one of claims 1 to 13 and having a high softening point of 250 ° C to 320 ° C.   A carbon fiber pitch produced according to at least one of claims 1 to 13 and having a weight average molecular weight of 1,000 to 10,000.   A carbon fiber pitch produced according to at least one of claims 1 to 13 and having an oxygen saturation of 106% or less.   A carbon fiber pitch produced according to at least one of claims 1 to 13 and having a quinoline insoluble (QI) content of 5 wt% or less.   A pitch for carbon fiber having a weight average molecular weight of 1,000 to 10,000 and a quinoline insoluble (QI) content of 5% by weight or less.

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