JP2010539341A - Paper containing polybenzazole or its precursor - Google Patents

Abstract

ここで、Ａｒ^１およびＡｒ^２は、それぞれ独立に、炭素原子数４〜１２のパラまたはメタ芳香族基であり、ＸおよびＹは、同一または異なり、Ｏ、ＳおよびＮＨから選択され；ｎは０または１であり、そして上記紙は不可抽出性リン化合物を含有しないかあるいは実質的に含有しない。
この紙は、電気絶縁材料、ハニカム構造または構造材料を製造するために特に好適である。
【選択図】なしThe present invention relates to a fiber, pulp, fibril, floc and fibrid having a polybenzazole structure having a repeating unit of formula (I) and / or (II) or a polybenzazole precursor structure having a repeating unit of formula (III) Relates to a paper containing at least one of the above.

Where Ar ¹ and Ar ² are each independently a para- or metaaromatic group having 4 to 12 carbon atoms, X and Y are the same or different and are selected from O, S and NH; 0 or 1 and the paper contains no or substantially no non-extractable phosphorus compounds.
This paper is particularly suitable for producing electrically insulating materials, honeycomb structures or structural materials.
[Selection figure] None

Description

  The present invention relates to a paper containing at least one of fibers, pulps, fibrils, flocks and fibrils having a polybenzazole structure or a polybenzazole precursor structure. The invention further relates to a method for producing such paper and its use.

  EP 07008742 has air substituents such as hydroxy, thiohydroxy or amine groups using an air gap wet spinning process, jet spinning process or other conventional methods to obtain fibers, pulp, fibrils or fibrids By applying an optically anisotropic dope containing a high molecular weight aromatic polyamide at a high concentration in an acidic solvent, followed by heat treatment, fibers, pulp, fibrils or fibrils having excellent performance including mechanical properties are obtained. It is described that it can.

  The present invention relates to a fiber, pulp, fibril, floc and fibrid having a polybenzazole structure having a repeating unit of formula (I) and / or (II) or a polybenzazole precursor structure having a repeating unit of formula (III) On paper containing at least one of:

Where Ar ¹ and Ar ² are each independently a para- or metaaromatic group having 4 to 12 carbon atoms, X and Y are the same or different and are selected from O, S and NH; 0 or 1 and the paper contains no or substantially no non-extractable phosphorus compounds.
The paper contains less than 0.15% by weight of non-extractable phosphorus compounds.

  Paper made from fibers having a polybenzazole structure is known in the art. For example, JP-A-10-096175, JP-A 2001-248091 and WO2007 / 076332. JP 10-096175 relates to a nonwoven sheet rather than paper. In addition, these sheets and paper are made from fibers spun from a polyphosphoric acid spinning dope. Therefore, these papers contain a significant amount of non-extractable phosphorus compounds and at least 0.25% by weight of polyphosphoric acid remains even when removed by the most advanced methods. According to normal industrial means, about 0.4% by weight of polyphosphoric acid remains in the fiber (eg Hu X. B. and Lesser A. J .; Abstract of Papers of the American Chemical Society 2004, 227: U562 U562).

The terms “para” and “meta” relate to the position of two amino groups or two carbonyl groups in the aromatic ring. When Ar ¹ and / or Ar ² contains a condensed aromatic ring, neither para nor meta positions exist correctly. However, positions corresponding to these are called pseudo-para and pseudo-meta positions, and are included in the definitions of “para” and “meta”.
The paper described above contains no or substantially no non-extractable phosphorus compounds. This means that it contains less than 0.15% by weight of non-extractable phosphorus compounds, preferably no non-extractable phosphorus compounds.
The above fibers, pulp, fibrils, flocks or fibrides are produced by a process comprising the steps of spinning or extruding the dope to solidify it with a coagulating liquid and then obtaining the fibers as described in EP 07008742 .

  The invention further relates to a precursor paper which itself has excellent properties and is therefore used as such. This precursor paper contains a polybenzazole precursor having a repeating unit of the formula (III):

Here, Ar ¹ and Ar ² are each independently an aromatic group having 4 to 12 carbon atoms, Ar ¹ and Ar ² have a para or meta configuration, and X and Y are the same or different, Selected from O, S and NH; n is 0 or 1;

Examples of Ar ¹ include phenylene, naphthalenediyl, and divalent heteroaromatic groups. Ar ¹ may be substituted with a hydroxy and / or halogen group.
Ar ¹ is preferably selected from the following.

Ar ² is a trivalent or tetravalent aromatic group having 4 to 12 carbon atoms. Examples of Ar ^2, benzenetricarboxylic - can be exemplified a or tetrayl, and a trivalent or tetravalent heterocyclic group as Ar ² - or tetrayl, naphthalene tricarboxylic - or tetrayl, diphenyl birds. These Ar ² sites may be substituted with hydroxy and / or halogen groups.

Ar ² is preferably selected from:

A benzene group is the most preferred Ar ² group.

In a preferred embodiment, Ar ¹ is para- or meta-phenylene:

And Ar ² is

Where X and Y are O and the straight line represents a bond,
It is.

  In addition to the above polybenzazole, the fiber may be a copolymer having a repeating unit represented by the formula (IV).

In formula (III), Ar ¹ groups each independently have the above-mentioned meaning. Preferred Ar ¹ groups are para- or meta-phenylene.

Polybenzazole is 40 to 100 mol% of repeating units represented by the formula (I) and / or (II), 60 to 0 mol% of repeating units represented by the formula (IV), and 100 mol% in total. It is preferable to contain.
The polybenzazole is more preferably 60-100 mol% of repeating units represented by the formula (I) and / or (II) and 40-0 mol% of repeating units represented by the formula (IV) 100 mol%.
Since X is an oxygen atom (—O—), a sulfur atom (—S—) or an imino group (—NH—), polybenzazole is derived from a precursor of a polymer having an imidazole, thiazole and / or oxazole ring. Obtainable.
A polybenzazole precursor having one or more of the following repeating units is particularly preferred.

  Methods for producing these polymers and methods for producing fibers, pulp, fibrils, flocks or fibrids are described in European patent application EP 07008742, which is included in the prior art.

For example, as described in US Pat. No. 6,890,636, PBO papers are known in the art, but such papers are inherently used in spinning dopes for fiber production and do not completely remove phosphoric acid. Contains a considerable amount. The PBO paper of the present invention contains less than 0.15% by weight of non-extractable phosphorus compounds (ie primarily phosphoric acid), preferably even less, such as less than 30 ppm, and most preferably no or virtually no phosphorus compounds. Do not contain (when the spinning dope does not contain any phosphoric acid). It is known that a small amount of phosphoric acid degrades the PBO fiber material and greatly impairs the strength of the paper, so producing PBO paper that is free or at least substantially free of phosphoric acid is It will be of utmost importance if the paper maintains its strength for a long time. The unique method of the present invention for producing PBO paper still belongs to a method for obtaining a closed PBO structure from a ring-opening precursor structure having OH, SH or NH ₂ groups. Due to these hydrophilic groups, the precursor is dissolved in a hydrophilic solvent such as water, alcohol, water-alcohol mixture and the like. Whereas PBO is practically only soluble in spinning dopes containing phosphoric acid, the precursors of the present invention can form dopes in the hydrophilic solvent without the use of any phosphoric acid. Such a spinning dope can be a fiber, pulp, fibril, flock or fibrid that is completely or virtually completely free of phosphorus compounds. PBO paper containing less than 0.15% by weight of phosphorus compounds is not known. Known PBO papers made from PBO-polyphosphoric acid containing spin dopes result in papers having (not much) more than 0.15% by weight non-extractable phosphorus. Although usually not preferred, a small amount of phosphoric acid or other phosphorus compound can be added to the spinning dope to provide a paper with a trace amount (eg, less than 0.15% by weight) of phosphorus. The amount of phosphorus present in the paper can be readily determined using standard methods such as spectroscopic analysis or titration.

  The paper of the present invention may contain a combination of fibers, pulp, fibrils, flocks or fibrids, such as a combination of fibrils and flocks. The paper of the present invention is produced by a conventional papermaking process in which the papermaking material is processed to allow the addition of common additives and auxiliary materials such as pigments, binders, silicates, fillers and other additives. Can be manufactured. The paper thus obtained may be further processed, for example, by further improving the density of the paper by applying a known glossing method.

The term "fiber, pulp, fibril, floc and fibrids" are well known in the art, can be found in, for example, ^{Textile Terms and Definitions, 2 nd Ed} , 1955.
The term “fibrid” refers to a film-like piece that is not granular. Fibrids have an average length of 0.2 to 1 mm and a length: width aspect ratio of 5: 1 to 10: 1. The thickness dimension is on the order of a fraction of a micron. Such fibrids are used in a wet state when fresh and are deposited as a binder that physically wraps around the floc component of the paper. Fresh fibrids and fibrids with a drying history can be used in the paper of the present invention.
The term “floc” typically refers to short fibers having a length of 2-12 mm and a linear density of 1-10 decitex. The flocs may be fresh or have a drying history. If fresh, it has never been used in any product before.

  Paper pulp may consist of flocks and fibrids and generally consists of about 50-60% by weight fibrids and 40-50% by weight flocs. Even after pulverization and kneading, flocs in the aramid paper pulp are bound to some extent by fibrids. Fibrids in the dry state are not very useful as binder materials when compared to fibrids that are bonded or folded together and have no fresh drying history; however, their randomness, rigidity, irregularity, The shape helps to increase the porosity of the paper structure that is the final product. For the purposes of the present invention, these fibrid and floc components collected from dry paper may be referred to as fibrids with a drying history and flocs with a drying history.

  Dry paper sheets containing polybenzazole precursors can be processed by a high speed kneader such as an air turbulent grind mill known as Turbomill or Ultra-Rotor and then purified in the wet state. . Air turbulent grind mills are preferred for crushing paper that has been glossed; however, the use of a grind mill results in a slightly shorter fiber length. When paper pulp having a short fiber length is used for the paper of the present invention, the strength when wet is slightly reduced, and the continuous operability of the paper processing machine tends to deteriorate.

  Paper made from a polybenzazole precursor material can be used as such. As shown in the examples below, this paper has excellent properties. However, the properties of the paper are easily changed or improved by functionalizing at least some of the free XH and YH groups, such as OH groups. These free radicals react with monomers and polymers with functional groups such as esters, isocyanates, epoxides and other functionalizing agents to form a covalent bond between X and / or Y and the functionalizing agent. Can do. If some of the free XH and YH groups are substituted with functional groups, these papers can be heat treated to convert the polymer precursor to a ring-closed PBO polymer by a cyclization process, which can also be used as a functionalized PBO paper. Good.

  Functionalization of all or part of the XH and YH groups can be performed at various stages of the papermaking process. Therefore, monomer

It is possible to functionalize (part of) the XH and YH groups therein and then polymerize with the monomer ClOOC—Ar ¹ —COOCl. This functionalized polymer can then be processed by any of the methods described above to obtain the paper of the present invention.

Functionalization can also be performed on the precursor polymer or polybenzazole obtained by polymerizing the monomers. These polymers will have XH and / or YH groups that can be functionalized by reacting with a functionalizing agent. These polymers can be functionalized at any stage of the papermaking process. Thus, the polymer can be functionalized immediately after monomer polymerization, but it can also be functionalized in the form of fibers, pulp, fibrils, flocks or fibrides, or after the paper has been made. In most cases in the latter method, only the outer surface of the fiber, pulp, fibril, flock or fibril can be easily functionalized. This can be an advantage when only partial functionalization is desired.
This method makes it possible to produce papers whose properties have been altered by functionalization such as coloring, smoothing, imparting waterproofing, increasing or decreasing electrical conductivity and making fireproof paper.

  Since the polymer precursor is synthesized and spun from a solution that will not contain the phosphorus compound, the resulting PBO can also be free of the phosphorus compound. This means that it is no longer necessary to produce paper from an almost insoluble PBO polymer, the paper making process can be carried out with easily soluble polymer precursors, and the conversion to PBO after paper production is It is a further advantage in that it is done.

  Since the paper of the present invention generally exhibits a lower porosity than PPTA paper, it is extremely suitable for electrical applications such as electrical insulation materials. This paper is further suitable for application to honeycomb structures and structural materials.

The paper of the present invention is a known paper, as shown in the EAB (elongation at break) and TI (tenacity index) data, both the paper containing the PBO precursor and the PBO paper. It has extremely high strength. For example, the paper of the present invention surpasses PPTA paper and surpasses even Nomex®, which is considered the strongest paper known to date.
This extreme strength of the paper of the present invention makes it possible to produce extremely thin paper. The paper of the present invention also has a thermal stability that exceeds PPTA paper and Nomex®.
Because of the extraordinary strength of the paper of the present invention, paper having a basis weight between 1 and 16 g / m ² can be produced. The term “basis weight” is a metric unit that represents the weight of a paper, based on a paper sheet of the same square meter, regardless of the paper grade.

  The invention is described in more detail by the following embodiments. However, the present invention is not limited by these embodiments.

General matters :
These results are the following repeating units:

And a corresponding repeating unit of the following:

It was obtained using a ring-closing polymer having Where Ar ¹ = para-phenylene and Ar ² = diphenylene.
abbreviation:
NMP = N-methylpyrrolidone DHB = dihydroxybenzidine (4,4′-diamino-3,3′-dihydroxydiphenyl)
TDC = terephthalic acid dichloride PPD = para-phenylenediamine PPTA = para-phenyleneterephthalamide

Example 1
Polymerization to polybenzazole precursor 2.25 L NMP / CaCl ₂ and 1.75 L NMP together with pre-dried DHB (140 ° C. under vacuum, 24 hours) were charged into a 10 L Drais reactor and stirred for 30 minutes DHB was dissolved. After cooling to 5 ° C., TDC was added while stirring (250 rpm) was continued. A sample was taken after 50 minutes and 1.8 L of NMP was added. The mixture was stirred for 30 minutes, another sample was taken, and 1.8 L NMP was added again. The mixture was stirred for 30 minutes and drained from the bottom valve. By applying this method, the polymer concentration of the first sample is 7.4%, the polymer concentration of the second sample (after dilution with NMP) is 5%, and the polymer concentration of the final product is 4% Met. The relative viscosity of the reaction product was 3.43.
The polymerization method for the second batch was the same as above except that a sample was taken after 60 minutes and 4.0 L of NMP was added. The mixture was stirred for 30 minutes and then discharged. By applying this method, the polymer concentration of the first sample was 7.4% and the polymer concentration of the final product was 4%. The relative viscosity of the reaction product was 3.06.
These polymerization batches were mixed prior to spinning.

Comparative Example 1
Polymerization of PPTA para-phenylene terephthalamide was performed using a 160 L Drais reactor. After the reactor was thoroughly dried, 64 L of NMP / CaCl _{2 with} a CaCl ₂ concentration of 2.5 wt% was added to the reactor. Then 1,522 g of PPD was added and dissolved at room temperature. The PPD solution was then cooled to 5 ° C. and 2,824 g of TDC was added. After the addition of TDC, the polymerization reaction was continued for 45 minutes. The polymer solution was then neutralized with a calcium oxide / NMP slurry (780 g CaO in NMP). After adding the CaO slurry, the polymer solution was stirred for an additional 30 minutes. This neutralization was performed to remove hydrochloric acid (HCl) produced during the polymerization. A gel-like polymer solution with a PPTA content of 4.5% by weight and a relative viscosity of 3.0 (in 0.25% H ₂ SO ₄ ) was obtained.
This product had an eta rel (η _rel ) of 2.4 and a polymer concentration of 3.6% and was used to spin pulp as well as fibrids. Water was used as a coagulant.

Example 2
Preparation of fibrids and pulp The solutions of Example 1 and Comparative Example 1 were spun at 20 L / h through a jet spinning nozzle (spinning hole 500 μm). Water was added through an annular channel flowing perpendicular to the polymer stream. During spinning, the polymer flow was kept constant, but the coagulation pressure was varied to obtain different samples, ie to vary the product SR (° SR).
Pulp spinning The solutions of Example 1 and Comparative Example 1 were spun into pulp through a single-hole jet spinning nozzle (spinning hole 350 μm). The solution was spun in a low pressure zone. An independent air jet was used through the annular channel at right angles to the polymer flow towards the same zone where air expansion occurred. Thereafter, in the same zone, the pulp was coagulated with water by a method in which a coagulant jet was applied through an annular channel at an angle in the polymer flow direction.
To spin pulp with different SR values (° SR), the polymer flow was varied while maintaining the air pressure constant. All samples were washed with water after spinning.
Characteristic value data of the process and fibrids and pulp obtained in Example 2 are shown in Table 1:

Example 3
Papermaking from fibrid Handmade paper was produced from samples A1 and B1 to B4 having different basis weights and 100% fibrids of Comparative Examples D1 to D4 and E1 using a Rapid Kothen machine. The dehydrated sheet was dried between two blotter papers under vacuum (95 ° C., 1,000 mbar, 20 minutes). The paper data is shown in Table 2.
Note the low caliper thickness (paper thickness) and high density compared to the comparative paper. The TI (tensile index) is 3-5 times higher for the paper of the present invention than the pulp-based comparative paper when compared at the same basis weight. The EAB is also higher for the paper of the present invention.

Example 4
Papermaking from pulp Handmade paper was produced from 100% pulp of Samples A and E having a basis weight of around 100 g / m ² by the same procedure as Example 3 using a Rapid Kothen machine. The paper data is shown in Table 3.

Example 5
Heat treatment of the paper In order to convert the above polybenzazole precursor paper into polybenzazole paper, heat treatment was performed in an inert atmosphere. The procedure is as follows: the sample was placed in a nitrogen streamed oven and heated at a heating rate of 5 ° C./min. When the temperature reached 440 ° C., the sample was immediately removed from the oven. Table 4 shows the characteristic value data of the samples before and after the heat treatment. IR spectra of the samples were recorded using a Varian FTS-575c infrared spectrometer equipped with a Thunderdome ATR accessory. This spectrum confirmed that the paper had been converted to polybenzazole paper with a conversion rate exceeding 95%.
TGA experiments were performed in nitrogen gas using Setaram TGA / DSC 111. First, paper samples were cut into small pieces and placed in platinum (open) cells. The sample weight used was between 10 and 20 mg. The sample was heated from 20 ° C. to 700 ° C. at a heating rate of 10 ° C./min.
The decomposition start point Td was determined by the temperature at which a weight loss of 1% by weight was observed. For samples B5 and A1, Td was determined after the conversion that occurred between 250 and 400 ° C. was completed. The results are shown in Table 4.

Example 6
Production of functionalized paper Precursor paper (paper sample B5), polybenzazole paper (paper sample B6) and PPTA paper (paper sample D1) obtained by heat-treating the precursor paper, reactive colorant (Cibacron Dark Blue S-GL; manufactured by Ciba, Switzerland) was stained according to the following procedure:
A solution of 6 g NaCl in 200 mL softened water was prepared at 80 ° C. After adding 0.4 g of Cibacron Dark Blue S-GL, the solution was stirred for 20 minutes and cooled to 60 ° C. 4.3 g of Na ₂ CO ₃ .10H ₂ O was added, and the solution was stirred at 60 ° C. for 30 minutes to obtain a staining solution.
Samples B5, B6 and D1, each 5 cm long and 1 cm wide, were immersed in the staining solution at 60 ° C. for 45 minutes and then rinsed in running water at about 50 ° C. for 10 minutes. These samples were neutralized in a 1% acetic acid bath and washed with cold running water for 15 minutes.

  The present invention provides aromatic polyamides functionalized with reactive functional groups that can be used to facilitate the conjugation of aramids to conjugation partners. As shown in Table 5, the functionalized aramid (sample B5) was fully converted by heat treatment from unfunctionalized aramid D1 and sample B6 having a fully cyclized polybenzazole structure from B5. Compared with B6 which does not have, excellent dyeability is exhibited.

Claims (13)

At least of fibers, pulps, fibrils, flocs and fibrids having a polybenzazole structure having a repeating unit of formula (I) and / or (II) or a polybenzazole precursor structure having a repeating unit of formula (III) Paper containing one type:

Where Ar ¹ and Ar ² are each independently a para- or metaaromatic group having 4 to 12 carbon atoms, X and Y are the same or different and are selected from O, S and NH; 0 or 1 and the paper contains no or substantially no non-extractable phosphorus compounds. Monomer having the formula ClOOC-Ar ¹ -COOCl and the formula

Where Ar ¹ and Ar ² are each independently a para- or metaaromatic group having 4 to 12 carbon atoms, X and Y are the same or different and are selected from O, S and NH; 0 or 1
And a monomer having the formula (III)

Here, Ar ¹ , Ar ² , X, Y and n have the above-mentioned meanings,
A precursor structure containing repeating units of
Optionally, the precursor structure is then cyclized in a liquid containing no or substantially no phosphorus compound to give formula (I) and / or (II)

Here, Ar ¹ , Ar ² , X and Y have the above-mentioned meanings,
The paper of claim 1 obtained as a polybenzazole structure having repeating units of:   The paper of claim 1 or 2, wherein at least a portion of XH and / or YH is functionalized. It has a basis weight of 1~16g / ^{m 2,} any one of the paper of claims 1 to 3. A mixture of at least one fiber, pulp, fibril, floc and fibrid having a polybenzazole structure of formula (I) and / or (II) or a polybenzazole precursor structure of formula (III) and PPTA fibrid The paper according to any one of claims 1 to 4, comprising: Monomer having the formula ClOOC-Ar ¹ -COOCl and the formula

Where Ar ¹ and Ar ² are each independently a para- or metaaromatic group having 4 to 12 carbon atoms, X and Y are the same or different and are selected from O, S and NH; 0 or 1
And a monomer having the formula (III)

Here, Ar ¹ , Ar ² , X, Y and n have the above-mentioned meanings,
A precursor structure containing a repeating unit represented by:
Optionally, the precursor structure is then cyclized by heating in a liquid containing no or substantially no phosphorus compound under an inert atmosphere to give formula (I) and / or (II)

Here, Ar ¹ , Ar ² , X and Y have the above-mentioned meanings,
A polybenzazole structure having a repeating unit of
Then producing fibers, pulp, fibrils, flocks or fibrils from the precursor or the polybenzazole structure;
These papers are then produced by a conventional papermaking process,
6. A method for producing paper according to any one of claims 1-5, optionally comprising subsequently performing one or more of a glossing step, a heating step, a drying step and a functionalization step. . Functionalizing the at least a portion of the XH-groups and / or YH group Ar ² by treating the monomer and / or precursor structures and / or polybenzazole structure functionalizing agent The method of claim 6. Monomer having the formula ClOOC-Ar ¹ -COOCl and the formula

Where Ar ¹ and Ar ² are each independently a para- or metaaromatic group having 4 to 12 carbon atoms, X and Y are the same or different and are selected from O, S and NH; 0 or 1
And a monomer having the formula (III) is polymerized in an equivalent amount in a liquid containing no or substantially no phosphorus compound.

Here, Ar ¹ , Ar ² , X, Y and n have the above-mentioned meanings,
A precursor containing a repeating unit of
Then producing fibers, pulp, fibrils, flocks or fibrils from the precursor,
Then, these papers are manufactured by a conventional papermaking process,
6. A method for producing paper according to any one of claims 1-5, optionally comprising subsequently performing one or more of a glossing step, a heating step, a drying step and a functionalization step. .   The obtained paper is subjected to a cyclization from a polybenzazole precursor having the formula (III) to a polybenzazole containing the structure of the formula (I) and / or (II) under an inert atmosphere. The method according to claim 7, wherein heating is performed. To functionalize at least a portion of the XH-groups and / or YH group Ar ² by treating the monomer and / or precursor structures and / or polybenzazole structure functionalizing agent The method of claim 8 or 9. Structure IV

Here, each Ar ¹ site has the same meaning as described above.
11. The method of any one of claims 6-10, further comprising applying a conventional papermaking process using at least one of fibers, pulp, fibrils, flocs and fibrids having the following:   The electrically insulating material containing the paper of any one of Claims 1-5.   Use of the paper according to any one of claims 1 to 5 for producing an electrically insulating material, a honeycomb structure or a structural material.