JPH0633595B2 - High-performance paper made of fibrils of thermotropic liquid crystal polymer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to high performance papers comprising fibrils of thermotropic liquid crystal polymer.

(Prior Art) Papers made from polymeric materials are used in many applications including filter media and electrical insulation. In this regard, for example, US Pat. Nos. 2,988,782; 3,080,272 and 3,101,294, and GIen, w. “Synthetic Paper”.
See Paper Technology, Vo1.5, NO.2, pp.137-142 (1964). However, such synthetic fiber paper has a high temperature environment (eg,
It is often not suitable for use in environments where the temperature exceeds 200 ° C) or where paper may come into contact with corrosive chemicals or solvents. Therefore, there is a need to develop papers made of polymeric materials that are resistant to solvents and corrosive chemicals and that are suitable for use at high temperatures.

It is also known to those skilled in the art that heat treatment of a liquid crystal polymer shaped article increases the melting temperature, molecular weight and mechanical properties of the polymer (eg, US Pat. No. 3,975,48).
7; 4,183,895 and 4,247,514).

OBJECT OF THE INVENTION Accordingly, it is an object of the present invention to provide a paper that exhibits desirable temperature stability.

Another object of the invention is to provide a paper that exhibits desirable chemical and solvent resistance.

Yet another object of the present invention is to eliminate the above-mentioned drawbacks of the prior art.

(Structure of the Invention) According to the present invention, a paper in which fibrils of a polymer capable of forming an anisotropic molten phase are bonded to each other, wherein the polymer contains 10-mol% or more of 6-oxy-2-naphthoyl repeating units. A paper excellent in heat stability, chemical resistance and solvent resistance, which is a wholly aromatic polymer. That is, the paper consists essentially of fibrils of a polymer capable of forming an anisotropic melt phase, the fibrils being joined together to form a monolithic paper.

Thermotropic liquid crystal polymers are polymers that are liquid crystalline (ie anisotropic) in the melt phase.
Polymers of this type have been described by various terms including "liquid crystalline", "liquid crystalline" and "anisotropic". Briefly, this type of polymer is believed to contain a regular parallel arrangement of molecular chains. The state in which the molecules are arranged in this way is often called a liquid crystal state or a nematic phase of a liquid crystal substance. Such polymers are generally elongated, flat, fairly rigid along the long axis of the molecule, and are made from monomers with multiple chain extension bonds, usually in either coaxial or parallel relationship.

Such polymers readily form liquid crystals in the melt phase (ie, exhibit anisotropy). Such characteristics can be confirmed by a conventional polarization technique using a crossed polarizer. More specifically, the confirmation of the anisotropic molten phase can be performed by using a Leitz polarization microscope and observing the sample placed on the Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times. The polymer used in the present invention is optically anisotropic. That is, it transmits light when inspected between crossed polarizers. Even in a stationary state, if the sample is optically anisotropic, it transmits polarized light.

Thermotropic liquid crystal polymers suitable for use in the present invention include fully aromatic polyesters, aromatic-aliphatic polyesters, aromatic polyazomethines, fully and non-fully aromatic poly (ester-amides) and aromatic polyester- There are, but are not limited to, carbonates.

Fully aromatic thermotropic liquid crystal polymers are polymers composed of repeating components that impart at least one aromatic ring to the polymer backbone and allow the polymer to exhibit anisotropy in the melt phase. Such components include, but are not limited to, aromatic diols, aromatic amines, aromatic dicarboxylic acids and aromatic hydroxy acids. Examples of components that can be present in the thermotropic liquid crystal polymer used in the present invention include the following, but are not limited thereto.

Preferably, the thermotropic liquid crystal polymer used in the present invention contains about 10 mol% or more of repeating units containing a naphthalene moiety. The preferred naphthalene-based component is 6-
There are oxy-2-naphthoyl, 2,6-dioxynaphthalene and 2,6-dicarboxynaphthalene.

Specific examples of suitable aromatic-aliphatic polyesters include:
wJJackson, Jr., HF Kuhfuss and TFGray, Jr., Self-Reinforced Thermoplastic Polyester X7G-A, American Plastics Industry Association, Reinforced Plastics / Composite Section, 30th Annual Technical Conference (1975), Section 17-D, It is disclosed on pages 1-4. There is a copolymer of polyethylene terephthalate and hydroxybenzoic acid. Such copolymers are also disclosed in: WJJackso
n, Jr., and HF Kuhfuss, "Liquid Crystal Polymers: I. Preparation and Properties of p-Hydroxybenzoic Acid Copolymers", Journal o.
f Polymer Science, Polymer Chemistry Edition, Vo1.1
4, pp.2043-58 (1976).

Aromatic polyazomethines and methods for making them are described in U.S. Patent Nos. 3,493,522; 3,493,524; 3,503,739; 3,516,970; 3,51.
6,971; 3,526,611; 4,048,148; and 4,122,070. Specific examples of such polymers include:
Poly (nitrilo-2-methyl-1,4-phenylene nitriloethylidyne-1,4-phenyleneethylidine), poly (nitrilo-2-methyl-1,4-phenylene nitrilomethylidyne-1,4-phenylenemethylidine ), And poly (nitrilo-2-chloro-1,4-phenylene nitrilomethylidine-1,4-phenylenemethylidine).

Aromatic polyester-carbonates are described in U.S. Pat.
No. 7,143. Examples of such polymers are those consisting essentially of hydroxybenzoic acid units, hydroquinone units, carbonate units and aromatic carboxylic acid units.

One of the preferred liquid crystal polymers for use in the present invention is thermotropic wholly aromatic polyester. Recent publications disclosing such polyesters include: (a) Belgian Patents 828,935 and 828,936
No. 7, (b) Dutch Patent No. 7,505,551, (c) West German Patent No. 2,5
20,819; 2,520,820; and 2,722,120, (d) Japanese Patent Publication No. 50-432
23, 52-132116, 53-017692, and 53-021293, (e) U.S. Patent Nos. 3,991,013; 3,991,014; 4,057,597; 4,066,620;
4,075,262; 4,118,372; 4,146,702; 4,153,779; 4,156,
070; 4,159,365; 4,169,933; 4,181,792; 4,188,476;
4,201,856; 4,226,970; 4,232,143; 4,232,144; 4,238,
600; 4,245,082; 4,242,496; 4,267,304; and 4,269,
965; and (f) British Patent Application Publication No. 2,002,404
issue.

Fully aromatic polymers suitable for use in the present invention include the fully aromatic polyesters and poly (ester-amides) disclosed in the following US patents and patent applications assigned to the applicant: US Pat. No. 4,067,852. ; 4,083,8
29; 4,130,545; 4,161,470; 4,184,996; 4,219,461; 4,
238,599; 4,224,433; 4,256,624; and 4,279,803;
And US Patent Application No. 91,003 (filed on November 05, 1979); 12
8,759 (1980.03.10 application); and 214,557 (1980.12.0)
9 applications). The wholly aromatic polymers disclosed therein are generally capable of forming an anisotropic melt phase below about 400 ° C, preferably below about 350 ° C.

The production of wholly aromatic polymers, including wholly aromatic polyesters and poly (ester-amides), suitable for use in the present invention produces functional groups that undergo condensation to form the necessary repeating units by a variety of ester formation techniques. It can be carried out by reacting the organic monomer compound which it has. For example, functional groups of these organic monomer compounds include carboxylic acid groups, hydroxyl groups, ester groups,
There are acyloxy groups, acid halides, amine groups and the like.
The above-mentioned organic monomer compound can be reacted by a molten acidolysis method without the presence of a heat exchange fluid. In this method, when the monomers are first heated together, a molten liquid of the reactants is produced, and when the reaction is further continued, the produced polymer particles are suspended in the liquid. At the final stage of condensation, vacuum may be applied to facilitate removal of by-products volatiles (eg acetic acid or water).

U.S. Pat. No. 4,083,829 describes a slurry polymerization process, which can also be employed to produce fully aromatic polymers suitable for use in the present invention. According to this method,
The solid product is obtained in suspension in the heat exchange medium.

Whether employing the molten acidolysis method or the slurry polymerization method of U.S. Pat. No. 4,083,829, the organic monomer reactants which derive the wholly aromatic polymers of the present invention are modified by esterifying the normal hydroxyl groups of this monomer. It may be subjected to the reaction in the form (ie, as a lower acyl ester). The lower acyl group preferably has about 2 to 4 carbon atoms. Preferably, the acetic acid ester of the organic monomer reactant is subjected to the reaction.

Representative catalysts that can optionally be used in either the melt acidolysis method or the slurry polymerization method of US Pat. No. 4,083,829 include dialkyltin oxide (eg, dibutyltin oxide), diaryltin oxide, titanium dioxide, antimony trioxide, alkoxy. Titanium silicate,
Titanium alkoxides, alkali and alkaline earth metal salts of carboxylic acids (eg zinc acetate) Lewis acids (eg B
F ₃ ), gaseous acid catalysts such as hydrogen halides (eg, HC), and the like. Generally, the amount of catalyst used will be from about 0.001 to 1% by weight, based on the total weight of monomers, and most commonly about 0.0.
It is 1 to 0.2% by weight.

The wholly aromatic polymers suitable for use in the present invention tend to be substantially insoluble in common solvents and are therefore less susceptible to solution processing. However, as already mentioned, these polymers can be easily processed by general melt processing methods. Particularly preferred wholly aromatic polymers are soluble in pentafluorophenol.

Preferred wholly aromatic polyesters for use in the present invention are generally about 2,000 to 200,000, preferably about 10,000 to 5
It exhibits a weight average molecular weight of 0,000, more preferably about 20,000 to 25,000. The preferred wholly aromatic poly (ester-amide) s for use in the present invention are typically about 5,000 to 50,000,
Preferably about 10,000 to 30,000, for example 15,000 to 17,000
Shows the molecular weight of. These molecular weights can be measured by gel permeation chromatography and other standard measurement methods that do not involve solution formation of the polymer, such as the measurement of end groups by infrared spectroscopy on compression molded films. The molecular weight can also be measured by utilizing a light scattering method in the state of a pentafluorophenol solution.

Fully aromatic polyesters and poly (ester-amides) are commonly prepared in pentafluorophenol at 60 ° C.
At least about 2.0d when measured at a concentration of 0.1% by weight
/ G, for example, a logarithmic viscosity number of about 2.0 to 10.0 d / g (I.
V.) is shown.

A particularly preferred wholly aromatic polymer is the above-mentioned U.S. Pat.
161,470; 4,184,996; 4,219,461; 4,238,599 and 4,25
6,624 and US Patent Application No. 214,557 (US Patent No.
Corresponding to No. 4,330,457).

In the present invention, the aromatic ring present in the polymer main chain of the polymer component used in the present invention may have at least a part of hydrogen atoms bonded to the aromatic ring substituted. Such substituents include alkyl groups having 4 or less carbon atoms, alkoxy groups having 4 or less carbon atoms, halogens, and other aromatic rings such as phenyl and substituted phenyl. Preferred halogens are fluorine, chlorine and bromine. Although the bromine atom tends to desorb from organic compounds at high temperatures, bromine is more stable when attached to the aromatic ring than it is aliphatic, which makes it inconvenient for inclusion in possible substituents on the aromatic ring. Absent.

The wholly aromatic polyester disclosed in U.S. Pat. No. 4,161,470 is a melt-processable wholly aromatic polyester capable of forming an anisotropic melt phase below about 350.degree. This polyester consists essentially of the following repeating components I and II: I: II: This polyester contains about 10-90 mole% of Component I and about 10
~ 90 or of component II. In one aspect, the ingredients
II is about 65-85 mol%, preferably about 70-80 mol% (eg,
Present in an amount of about 75 mol%). In another embodiment, component II is present in much lower amounts of about 15-35 mol%, preferably about 20-30 mol%. Further, at least a part of the hydrogen atoms bonded to the ring is selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl and combinations thereof. Optionally substituted with other substituents.

The wholly aromatic polyester disclosed in U.S. Pat. No. 4,184,996 is a melt-processable wholly aromatic polyester capable of forming an anisotropic melt phase below about 325 ° C. This polyester essentially comprises the following repeating components I, II and II:
Consists of: I II: III: This polyester contains component I in an amount of about 30 to 70 mol%. Preferably, the polyester is about 40-60 mol%
Component I, about 20-30 mol% of component II and about 20-30 mol% of component III. Further, at least a part of the hydrogen atoms bonded to the ring is selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl and combinations thereof. Optionally substituted with other substituents.

The wholly aromatic polyester disclosed in U.S. Pat. No. 4,238,599 is a melt processable polyester that is capable of forming an anisotropic melt phase at temperatures up to about 320 ° C. This polyester consists essentially of the following repeating components I, II, III and IV: I: II: III: IV: Wherein R represents methyl, chloro, bromo, or a mixture thereof, and is a substituent for hydrogen bonded to the aromatic ring. This polyester contains about 20-60 mol% of Component I, about 5-18.
Mol% component II, about 5-35 mol% component III, and about 2
It consists of 0-40 mol% of component IV. Preferably, the polyester comprises about 35-45 mol% Component I, about 10-15 mol% Component II, about 15-25 mol% Component III, and about 25-35 mol% Component IV. However, the total amount of components II and III will be substantially equal to the amount of component IV. Further, at least a part of hydrogen atoms bonded to the ring has 1 to 4 carbon atoms.
Optionally substituted with a substituent selected from the group consisting of an alkyl group, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, and combinations thereof. The logarithmic viscosity number of this wholly aromatic polyester is
When dissolved in pentafluorophenol at a concentration of 0.1% by weight / volume at 60 ° C., at least 2.0 d / g (eg,
It is about 2.0 to 10.0 d / g).

The polyester disclosed in U.S. Pat. No. 4,219,461 is a melt processable wholly aromatic polyester capable of forming an anisotropic melt phase below about 320.degree. This polyester consists essentially of the following repeating components I, II, III, and IV: I: II: III: General formula (Wherein Ar is a divalent group containing at least one aromatic ring), IV: general formula (Wherein Ar 'is a divalent group containing at least one aromatic ring).

This polyester contains about 20-40 mol% of Component I, 10 mol%
More than about 50 mol% of component II, more than 5 mol%, about
30 mol% of component III and more than 5 mol%, about 30 mol%
It consists of the following component IV. The polyester is preferably about 20-30 (eg, about 25) mol% of Component I, about 25-40.
(Eg, about 35) mol% component II, about 15-25 (eg, about 20) mol% component III, and about 15-25 (eg, about 20) mol% component IV. Further, at least a part of hydrogen atoms bonded to the ring is an alkyl group having 1 to 4 carbon atoms, or 1 carbon atom.
Optionally substituted with a substituent selected from the group consisting of alkoxy groups of ~ 4, halogen, phenyl, substituted phenyl and combinations thereof.

Ingredients III and IV are such that the divalent bonds connecting these moieties to other moieties in the main polymer chain are in a symmetrical arrangement on one or more aromatic rings (for example, these bonds may be linked to one another). It is preferably symmetrical in the sense that it is arranged in the para position or in a diagonal position when it is on the naphthalene ring). However, asymmetric components such as those derived from resorcinol and isophthalic acid may also be used.

Preferred components III and IV are those described in U.S. Pat.
No. 61. Preferred dioxyaryl components
III is: And a preferred dicarboxyaryl component IV is:

The polyester disclosed in U.S. Pat. No. 4,256,624 is a melt-processible wholly aromatic polyester capable of forming an anisotropic melt phase below about 400.degree. This polyester consists essentially of the following repeating components I, II, and III: I: II: General formula (Wherein Ar is a divalent group containing at least one aromatic ring), III: general formula (Wherein Ar 'is a divalent group containing at least one aromatic ring).

This polyester contains about 10-90 mol% of Component I, about 5-45.
It consists of mol% of component II and about 5-45 mol% of component III. Preferably, the polyester is about 20-80 mol%
Component I, about 10-40 mol% of component II and about 10-40 mol% of component III. More preferably, the polyester comprises about 60-80 mol% Component I, about 10-20 mol% Component
II and about 10-20 mol% of component III. Further, at least a part of hydrogen atoms bonded to the ring has 1 carbon atom.
Optionally substituted with a substituent selected from the group consisting of an alkyl group having 4 to 4, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, and combinations thereof.

Components II and III of this polyester are described in U.S. Pat.
Similar to components III and IV of the polyester disclosed in 19,461, it may be symmetrical or asymmetrical, but preferably symmetrical.

Preferred components II and III are those described in the aforementioned U.S. Patent No. 4,256,6.
It is described in No. 24. Preferred dioxyaryl components
II: And preferred dicarboxyaryl components III are: Is.

U.S. Pat.No. 4,330,457 (Application No. 214,557)
Melt processable poly (ester-amide) s capable of forming an anisotropic melt phase below about 400 ° C are disclosed. This poly (ester-amide) consists essentially of the following repeating components I, II, III and optionally IV: I: II: (In the formula, A is a divalent group containing at least one aromatic ring or a divalent trans-cyclohexane group), III: [In the formula, Ar is a divalent group containing at least one aromatic ring,
Y is O, NH or NR, and Z is NH or NR
(However, R is an alkyl group or aryl group having 1 to 6 carbon atoms), IV: (In the formula, Ar ′ is a divalent group containing at least one aromatic ring).

The poly (ester-amide) comprises about 10-90 mol% of component I, about 5-45 mol% of component II, about 5-45 mol% of component II.
III and about 0-40 mol% of component IV. Further, at least a part of hydrogen atoms bonded to the ring has 1 carbon atom.
Optionally substituted with a substituent selected from the group consisting of an alkyl group of ˜4, an alkoxy group of 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl and combinations thereof.

Preferred components II, III and IV are described in U.S. Pat.
No. 30,457. Preferred dicarboxyaryl components II are: Preferred component III is: Or And preferred dioxyaryl components IV are: Is.

The paper of the present invention consists of fibrils of thermotropic liquid crystal polymer (ie, a polymer capable of forming an anisotropic melt phase). The fibrils can be produced by several methods including mechanical subdivision of shaped articles such as as-spun thermotropic liquid crystal polymer fibers. As-spun fibers are highly oriented along their long axis (ie, the longitudinal axis) and, as opposed to their longitudinal axis, they are much less resistant to transverse stress. Therefore, when the fibers are subdivided to form pulp,
The fibers are easily torn longitudinally into much narrower fibrils. The fiber segmentation treatment is preferably performed in the state of an aqueous slurry.

The resulting pulp is generally an aggregate of fibrils that have been loosened, fibrillated, and / or branched. Due to these properties, the fibrils become entangled, so that the slurry can be scraped once with a net,
A thin but agglomerated mat can be formed. In addition,
“Pulp” refers to a process in which a group of shaped articles such as fibers is subjected to mechanical fragmentation or pulverization treatment to cause division, tearing, loosening, fibrillation, and / or shredding of fibers or shaped articles. , Generally means a unit with a smaller diameter. This enhances the entanglement between the constituent units, that is, "mutual felting", and enables the formation of a thin but agglomerated sheet. The fibers and / or fiber fragments may be further crimped, branched or bifurcated to improve mutual felting.

Typical solids content of pulp is liquid (eg water) 1
Per polymer of about 0.5 to 50 g, that is, solid content of about 0.05 to
It is within the range of 5% by weight. The preferred solids content range is about 0.5 to 2 weight percent solids. When making paper by wet deposition, a slightly dilute slurry (eg, about 0.01-
It is advantageous to cast the paper from a solids content of 1% by weight).

As used herein, the term "fragmentation treatment" means various mechanical operations in which a shaped article such as a fiber is subjected to a crushing or shearing force having a strength sufficient to break the shaped article into fibrils.
The subdivision processing step may include a series of operation techniques rather than a single operation. Such operations include the use of fluid or air perturbation (ie air fibrillation), the use of high shear (eg pulp refiners and open disc emulsifiers), repeated shredding and combined fluid shear (eg Waring). Blender), and a combination of crushing and mechanical shearing (eg, Jordan beater) and the like, but are not limited thereto. The use of surface wetting agents or 50% isopropanol or ethanol may facilitate polymer fibrillation.

The length: diameter ratio of the fibrils produced is typically greater than the length: diameter ratio exhibited by the fibers. For example, the fiber length: diameter ratio is generally about 30: 1 to 300.
Within the 1: range, this ratio of fibrils is about 50: 1.
Within the range of ~ 600: 1. The fibrils preferably have a diameter of about 0.5 to 5μ and a length of about 50μ to about 3 mm.

Fibers that undergo subdivision processing generally have a length of about 1/32 to 1 /
The size is 4 inches (0.8 to 6.4 mm) and the diameter is about 14 to 35 μ. The denier number of the fibers is preferably about 2-10. Fibers with a finer range than this, for example 0.5 to 100 denier (corresponding to a diameter of 7 to 100 μ), can also be used. Typical starting fiber lengths are in the range of 1/32 to 1/4 inch (0.8 to 6.4 mm). If the fiber length used at the time of departure is longer than 1/8 inch (3.2 mm), the pulp forming method adopted can reduce the length at the same time as fibrillation so that the agglomeration of pulp particles does not occur. Method should be used.
The length of fibrils produced will be generally proportional to the length of fiber used.

The presence of at least about 5 mol% of repeating units containing a 2,6-dioxyanthraquinone moiety in the thermotropic liquid crystal polymer reduces the amount of time and energy used for fibrillation and allows the fibers to have submicron sized fibrils. It can be easily broken.

The use of fibers is preferred, but shaped articles of other shapes and forms are also possible. For example, the polymer may be in the form of pellets or sheets. As used herein, "shaped article" means shaped articles formed by extrusion, molding, casting or other shaping means of particles, pellets, filaments, staple fibers, films, chips, sheets and other shapes. Is included.

However, it should be appreciated that the higher the degree of orientation of the polymer in the shaped article, the higher the aspect ratio (aspect ratio) of the fibrils produced. Therefore, in the production of the paper of the present invention, it is preferable to use shaped articles (eg, melt-spun fibers) that are highly oriented by the shaping operation in order to generate fibrils with a high aspect ratio.

The resulting fibrils are then slurried in a liquid that is a non-solvent for the polymers that make up the fibrils (eg, water) and collected (eg, by filtration) on a web or net and randomly (ie Form a web or sheet of fibrils arranged in a dimension. In addition to wet deposition, web formation can also be accomplished by air deposition techniques in which the fibrous material is entrained in and is entrained by a moving air stream. Since the fibrils formed are generally branched or branched in the longitudinal direction, there is a tendency for the fibrils to naturally stick to each other during the deposition of the fibrils.

The fibrils are combined using any suitable method to form a paper with the desired degree of structural integrity. That is, the paper produced bears at least its own weight, ie its own weight, and preferably exhibits integrity which makes it difficult to tear. Thus, such paper will take the form of a sheet or web. The fibrils may be bonded to each other thermally at a suitable temperature by conventional means such as heat pressing or calendering to bond the fibrils at at least their intersections. Since the polymers that make up the fibrils form an anisotropic melt phase, such fusion does not result in a significant loss of orientation (and thus of strength). This feature is in direct contrast to common thermoplastic polymers that do not form an anisotropic melt phase and therefore easily lose their orientation upon heating above their melting temperature.

A heat pressing process is an essentially batchwise operation in which a web of fibrils is pressed between two hot plates. Calendering is the passage of fibrils in the form of a web between heated rolls. It is preferred to use the padded backup roll in contact with the heated metal roll. The thermal bond temperature is generally in the range of about 100-250 ° C.

Bonding of the fibrils can also be performed with an adhesive. Adhesives include, but are not limited to, epoxy resins, thermosetting or thermoplastic resins including thermosetting polyesters, casein,
Water soluble adhesives such as guar gum or polyacrylic acid, solvent based adhesives, and emulsion or latex based adhesives such as styrene / butyl / acrylic copolymers. Application of the adhesive to the fibril web or sheet can be carried out using a kiss roll. Or
The adhesive may be sprayed or attached to the web by known emulsion methods (methods for wet-laid paper). The use of adhesives in such application methods is well known and will not require further explanation.

When employing thermal bonding, the temperature and method affect the physical properties of the paper produced. For example, about 140 ℃
The use of lower temperatures produces opaque paper. Such a paper is essentially a mat in which fiber particles (fibrils) are intertwined with each other, but has a considerably high porosity and a low density. On the other hand, when pressure or calendering is used together with a temperature above about 140 ° C. (especially about 170 ° C.), a transparent paper with a low porosity in the form of a film or a film like a glassine film is produced. Therefore, the use of excessive temperature and pressure in the calendering process should generally be avoided if it is desired to produce paper with a significantly higher porosity. This is because such temperatures and pressures increase the degree of fusion and compactness of the fibrils with a corresponding decrease in porosity. The strength of the applied pressure and the pressing time can also affect the degree of fusion.

The paper of the present invention has many advantageous properties due to the presence of the thermotropic liquid crystal polymer. Since the liquid crystal polymer is highly oriented in the as-spun state, the fibrils that make up the paper of the present invention have relatively high tensile strength and elastic modulus. Therefore, the paper made of such fibrils also exhibits a relatively high elastic modulus and tensile strength. Further, in the paper of the present invention, since the fibrils are oriented in the multidimensional (that is, random) direction inside the paper, such high tensile strength and elastic modulus are exhibited in the multidimensional (multidirectional). Paper basis weight, porosity,
The thickness and the like can vary depending on the amount of fibrils used, the pressure used to thermally bond the fibrils, and the like. However, the basis weight of the paper of the present invention is usually 3 to 20 ounces per square yard (100 to
It will be in the range of 680 g / m ² ).

The mechanical properties of the paper of the present invention can be further improved by heat treating the paper produced after papermaking. The heat treatment contributes to the improvement of the properties of the paper by increasing the molecular weight of the liquid crystalline polymer constituting the fibrils and its crystallinity, and at the same time raising the melting temperature of the polymer. Such heat treatment also serves to bind the fibrils.

Heat treatment of paper is carried out in an inert atmosphere (eg nitrogen, carbon dioxide,
Argon, helium) or flowing oxygen-containing atmosphere (eg air). It is preferred to use a substantially water-free, non-oxidizing atmosphere so as to eliminate the possibility of thermal decomposition. For example, the paper may be heat-treated at a temperature about 10 to 30 ° C. lower than the melting temperature of the raw liquid crystal polymer (at which temperature the fibrils are still solid). The heat treatment temperature is preferably as high as possible unless it becomes equal to or exceeds the melting temperature of the polymer. It is particularly preferable to gradually increase the heat treatment temperature as the melting temperature of the polymer rises during the heat treatment.

The heat treatment time is usually several minutes to several days or more, for example, about
Ranges from 0.5 to 200 hours or more. Preferably, the heat treatment is carried out for 1 to 48 hours, generally 5 to 30 hours.

Generally, the heat treatment time depends on the heat treatment temperature. That is, the higher the operating temperature, the shorter the heat treatment time required. Therefore, a polymer having a higher melting temperature can be heat-treated at a higher temperature without melting the polymer, and the heat treatment time can be shortened.

Preferably, the heat treatment increases the melting temperature of the polymer by at least
Perform under conditions sufficient to raise by 10 ° C. As a result of heat treatment, the melting temperature of the raw liquid crystal polymer is about 20-50
It is particularly preferable to raise the temperature by ° C. The amount of increase in the melting temperature achieved by the heat treatment depends on the use temperature, and the higher the heat treatment temperature, the larger the amount of increase.

The same effect can be obtained by heat-treating the fibril before being integrated with the paper. However, it is preferable to heat-treat the paper after forming it, because the heat-bonding step and the heat-treatment step can be combined and performed simultaneously.

In the present specification, the description that "the polymer can form an anisotropic molten phase at a temperature lower than ... ° C" means that the anisotropic molten phase is heated at a temperature lower than that temperature before the polymer undergoes heat treatment. It means that it can be formed.

The chemical resistance of the liquid crystal polymer also increases with the heat treatment, and the solubility in pentafluorophenol, which is one of the few solvents for thermotropic liquid crystal polymer, also gradually decreases as the heat treatment time increases, and finally the polymer becomes slightly ( Even a concentration of 0.1% by weight) will not dissolve.

The physical properties of paper can be modified by adding various additives to the pulp during the web forming process. For example, wetting agents, surface treatment agents, coloring agents, fillers and the like can be added. Such additives also include reinforcing fibers made of various materials, and as the reinforcing fibers, thermotropic liquid crystal polymer fibers, glass fibers, micro glass fibers, wood pulp, cotton and other cellulosic fibers, asbestos, mineral fibers, Mention may be made of ceramic fibers, metal fibers such as steel fibers, carbon fibers and non-liquid crystalline synthetic fibers such as viscose rayon, polyesters, polyolefins, nylon and polytetrafluoroethylene.
The proportion of such fibers is wide-ranging so as to produce a product with the desired properties. However, a typical blending ratio is generally less than 50% by weight,
50% by weight is composed of fibrils of thermotropic liquid crystal polymer. Preferably, the paper of the present invention consists essentially of fibrils of thermotropic liquid crystal polymers, so that the beneficial effects of such polymers can be maximized.

The size of a normal reinforcing fiber depends on the type of fiber and the physical properties required for the paper to be produced, but the diameter is about 1-50.
μ, and the length is in the range of about 1 to several inches.

The invention will be further described by the following examples. However,
These examples are examples of the present invention, and the present invention is not limited to the specific contents of the examples.

Example 1 40 mol% p-oxybenzoyl component and 6-oxy-
20 g of long fiber made of thermotropic liquid crystal polymer having a composition of 2-naphthoyl component of 60 mol% is about 1/8 to 1 /
Cut to lengths in the range of 4 inches (3.2 to 6.4 mm). Mix the cut fibers with 3 quarts (2.8) of water and Waring
Grind in a blender for about 1 hour to form a coarse pulp of fibrils.

The resulting slurry-like rough pulp is mixed with Ross and Sons.
Place in an emulsifier and further grind at the highest speed possible to form a finer pulp. The fibrils in this fine pulp have a length of 1/2 to 1/4 of the fibers when cut and a diameter of 1/2 to 1/5 of the fibers when cut. Crush 1
Approximately 2 g of crude pulp is added in batches.

Each batch is further diluted with water and a sheet of paper is made from this using a standard handmade paper machine equipped with a plastic mesh. Each of the resulting sheets is dried and calendered at a temperature of about 100-170 ° C to obtain paper. The higher the calendering temperature, the higher the density and strength of this paper.

Repeat the above operation, but prior to the papermaking process,
40 mol% of p-oxybenzoyl component and 6-oxy-2-
Fibers obtained by heat treating and chopping a thermotropic liquid crystal polymer consisting of 60 mol% of naphthoyl component are added to a batch of finely ground pulp in an amount of 25% by weight. The heat treatment of this fiber was carried out by raising the temperature of the fiber to a temperature of about 275 ° C. for about 16 hours and then holding it at about 275 ° C. for several hours. Calendering a sheet formed from this mixture at the same temperature as before gives a sheet with improved strength compared to the non-reinforced sheet.

The physical properties of some of the papers produced by the above method were measured and the test results are summarized in Table 1 below.

Example 2 6-oxynaphthoyl component 60 mol%, terephthaloyl component 20 mol%, p-aminophenol component 10 mol%, hydroquinone component 10 produced according to the method described in Example 1 of JP-A-57-172921. The method described in Example 1 is repeated using poly (ester-amide) filaments consisting of mol%. That is, instead of the long fibers of wholly aromatic polyester described in Example 1, the above poly (ester-amide) was used.
Fibrils are prepared from the long fibers of No. 1 in the same manner, paper is made, and calendered at a temperature of 200 ° C. or less to produce paper. The resulting paper exhibits substantially the same properties as described in Example 1.

Although the principle, preferred embodiments and details of implementation of the present invention have been described above, these are not intended to be limiting,
By way of example only, the invention is not limited to the particular embodiments described above. Various modifications can be made by those skilled in the art within the scope of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location D01F 6/84 311 7199-3B (72) Inventor Zyon Earl Castellitz, Roth Kauay, New Jersey, USA West Lake Shore Drive No.74 (56) References JP-A-53-35021 (JP, A)

Claims (21)

[Claims] 1. A paper in which fibrils of a polymer capable of forming an anisotropic melt phase are bound to each other, wherein the polymer contains 10-mol% or more of 6-oxy-2-naphthoyl repeating units. Paper with excellent thermal stability, chemical resistance and solvent resistance, characterized by being a polymer. 2. A paper according to claim 1 wherein the polymer is a wholly aromatic polyester or poly (ester-amide). 3. A polymer according to claim 1, which exhibits a logarithmic viscosity number of at least 2.0 d / g when dissolved in pentafluorophenol at a concentration of 0.1% by weight at 60 ° C. paper. 4. A paper according to claim 1 wherein the polymer is capable of forming an anisotropic melt phase at temperatures below 400 ° C. 5. The paper according to claim 1, wherein at least a part of the polymer fibrils has been previously heat-treated for a time and at a temperature sufficient to raise its melting temperature by 20 to 50 ° C. 6. The heat treatment temperature is higher than the melting temperature of the polymer.
The paper according to claim 5, which has a temperature range lower by 10 to 30 ° C. 7. The paper according to claim 5, wherein the heat treatment time is within a range of 0.5 to 200 hours. 8. The paper according to claim 7, wherein the heat treatment time is in the range of 1 to 48 hours. 9. The paper according to claim 8, wherein the heat treatment time is in the range of 5 to 30 hours. 10. The paper according to claim 5, wherein the heat treatment is performed in a non-oxidizing atmosphere. 11. The paper according to claim 10, wherein the atmosphere is substantially free of water. 12. The paper according to claim 10, wherein the heat treatment is performed in a nitrogen atmosphere. 13. The length: diameter ratio of the fibrils is 50:
The paper of claim 1 which is in the range of 1 to 600: 1. 14. The paper of claim 1 wherein said fibrils have a diameter in the range 0.5-5 microns. 15. The paper of claim 1 wherein the fibrils are thermally bonded. 16. The paper according to claim 15, wherein the fibrils are thermally bonded at a temperature of 100 to 250 ° C. 17. The paper according to claim 15, wherein the fibrils are thermally bonded under pressure. 18. The paper according to claim 17, wherein the fibrils are thermally bonded by heat pressing. 19. The paper according to claim 15, wherein the fibrils are thermally bonded by calendering. 20. The paper of claim 1 wherein the fibrils are bonded using an adhesive. 21. Weighing from 3 to 20 ounces per square yard (100 to
The paper according to claim 1, which is in the range of 680 g / m ² ).