JP5571943B2 - Heat resistant flame retardant paper - Google Patents

Description

  The present invention relates to a heat-resistant flame retardant paper comprising amorphous polyetherimide (hereinafter sometimes abbreviated as amorphous PEI) fiber and heat-resistant fiber having a melting point or a thermal decomposition temperature of 200 ° C. or higher. It can be effectively used for many applications including the industrial materials field and the electrical and electronic field.

  Both heat resistance and flame retardance are widely demanded for electrical insulating materials used in various electric / electronic devices and various industrial materials.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 9-139113) discloses a heat-resistant composition comprising a polymetaphenylene isophthalamide pulp, a polymetaphenylene isophthalamide short fiber, and a polyester compound melted and solidified from the fiber state. Paper is disclosed.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2001-248091) includes a polybenzazole fiber having a Na ion content of 6000 ppm or less and an aspect ratio of 50 to 5000, and has high heat resistance. • Highly flame retardant organic fiber paper is disclosed.

JP 9-139113 A JP 2001-248091 A

  However, in the heat-resistant paper of Patent Document 1, since the aramid compound has a high equilibrium moisture content, for example, when it is used for a printed wiring board or the like, when it is exposed to a high temperature, it rapidly causes water evaporation and thereby wiring. There is a risk of giving fatal defects to the circuit.

  Further, in the high heat resistance / high flame retardant organic fiber paper of Patent Document 2, neutralization treatment with sodium hydroxide is indispensable in the production process of polybenzazole fiber. When this paper is used, polybenzazole fiber is used. There is a risk that the insulating properties may be reduced by sodium hydroxide adhering to the surface.

Accordingly, an object of the present invention is to provide a heat-resistant flame-retardant paper that is not only excellent in both heat resistance and flame retardancy, but also capable of reducing the moisture content in an equilibrium state.
Another object of the present invention is to provide a heat-resistant flame-retardant paper that is excellent in both heat resistance and flame retardancy without being affected by the reduction in insulation properties due to sodium hydroxide.

  As a result of intensive studies on the above problems, the present inventors firstly used (i) an amorphous PEI polymer having a specific molecular weight distribution, which not only has excellent flame retardancy but also low smoke generation. It was found that amorphous PEI fibers with low flexibility and high temperature shrinkage can be produced, and (ii) when forming paper by combining such amorphous PEI fibers and heat resistant fibers, The present invention was completed by finding that the flame retardancy is improved, (iii) such paper has excellent heat resistance, and (iv) the paper can suppress the equilibrium moisture content to a low level. did.

  That is, the present invention relates to an amorphous polyetherimide fiber (A) formed from an amorphous polyetherimide polymer having a molecular weight distribution (Mw / Mn) of less than 2.5, a melting point or a thermal decomposition temperature. A heat-resistant flame retardant paper containing organic or inorganic heat-resistant fibers (B) having a temperature of 200 ° C. or higher.

  In the heat resistant flame retardant paper, the ratio (mass ratio) of the amorphous polyetherimide fiber (A) and the heat resistant fiber (B) is, for example, (A) / (B) = 30/70 to 98. It may be about / 2. Further, the total amount (A + B) of the amorphous polyetherimide fiber (A) and the heat resistant fiber (B) may be 60% by mass or more of the heat resistant flame retardant paper.

  In such heat-resistant flame retardant paper, for example, the equilibrium moisture content may be 3.0% or less, or the carbonization length according to the JIS L1091 A-4 method may be 10.0 cm or less. Furthermore, the dry heat shrinkage at 200 ° C. may be 4.0% or less.

  For example, the heat-resistant fiber (B) may be composed of at least one selected from the group consisting of wholly aromatic polyester fibers, glass fibers, polyphenylene sulfide fibers, para-aramid fibers, and polysulfonamide fibers. It is preferably composed of melt anisotropic fully aromatic polyester fiber.

The heat-resistant flame retardant paper of the present invention is not only excellent in both flame retardancy and heat resistance by using a specific amorphous PEI fiber and combining it with a heat-resistant fiber, but also in an equilibrium state. A heat-resistant flame retardant paper capable of suppressing the moisture content can be realized.
Thereby, the heat-resistant flame retardant paper of the present invention can lower the equilibrium moisture content, and can suppress deformation due to moisture absorption and destruction of equipment due to rapid steaming of moisture inside the paper.

  Hereinafter, the present invention will be described in detail. The heat-resistant flame retardant paper of the present invention includes at least amorphous PEI fibers formed from an amorphous PEI polymer having a molecular weight distribution (Mw / Mn) of less than 2.5, and heat resistant fibers. Yes.

(Amorphous polyetherimide fiber)
The amorphous PEI fiber used in the present invention is formed from an amorphous PEI polymer having a specific molecular weight distribution. By utilizing such a polymer, it is possible to improve the spinnability from the amorphous PEI polymer and to obtain amorphous PEI fiber having a small single yarn fineness suitable for paper use. And the obtained amorphous PEI fiber can improve the workability in the paper-making process performed next, and can improve the flame retardance.

(Amorphous polyetherimide polymer)
The amorphous PEI polymer will be described. The amorphous PEI polymer used in the present invention is a polymer containing an aliphatic, alicyclic or aromatic ether unit and a cyclic imide as repeating units, and has amorphous and melt moldability. If it is, it will not specifically limit. In addition, as long as the effect of the present invention is not inhibited, structural units other than cyclic imide and ether bond in the main chain of the amorphous PEI polymer, such as aliphatic, alicyclic or aromatic ester units, oxycarbonyl units Etc. may be contained.

  As a specific amorphous PEI polymer, a polymer having a unit represented by the following general formula is preferably used. Wherein R1 is a divalent aromatic residue having 6 to 30 carbon atoms; R2 is a divalent aromatic residue having 6 to 30 carbon atoms, 2 to 20 2 selected from the group consisting of an alkylene group having 2 carbon atoms, a cycloalkylene group having 2 to 20 carbon atoms, and a polydiorganosiloxane group chain-terminated with an alkylene group having 2 to 8 carbon atoms Valent organic group.

  As said R1 and R2, what has an aromatic residue and alkylene group (for example, m = 2-10) shown by the following formula group, for example is used preferably.

  In the present invention, 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride mainly having a structural unit represented by the following formula from the viewpoint of amorphousness, melt moldability, and cost. A condensate of the product with m-phenylenediamine is preferably used. Such polyetherimides are commercially available from Servic Innovative Plastics under the trademark “Ultem”.

The molecular weight of the amorphous PEI polymer used in the present invention is not particularly limited, but considering the mechanical properties, dimensional stability, and process passability of the resulting fiber, it is 390 ° C. and shear rate 1200 sec ⁻¹ . From the viewpoint, it is desirable that the weight average molecular weight (Mw) is 1000 to 80000. The use of a polymer having a high molecular weight is preferable because it is excellent in terms of fiber strength, heat resistance and the like, but from the viewpoint of resin production cost, fiberization cost, etc., it is more preferable that Mw is 10,000 to 50,000.

  In particular, the amorphous PEI polymer used in the present invention must have a molecular weight distribution (Mw / Mn), which is a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), of less than 2.5. It is. If the molecular weight distribution is larger than this, not only the workability and stability in the fiber production process are deteriorated, but also the heat resistance of the fiber obtained from this polymer is inferior.

  On the other hand, when the molecular weight distribution is 1, an ideal monodisperse polymer is obtained. From this viewpoint, the lower limit of the molecular weight distribution of the amorphous PEI polymer is preferably 1.0.

  For example, the molecular weight distribution of the amorphous PEI polymer is preferably 1.0 to 2.4, and more preferably 1.0 to 2.3. For example, such an amorphous PEI polymer having a narrow molecular weight distribution can be obtained, for example, by the method exemplified in Japanese Patent Publication No. 2007-503513, but is not limited thereto.

  Although details will be described later in the Examples section, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the molecular weight distribution mentioned here are, for example, gel permeation, which is a kind of size exclusion chromatography (SEC). It can be calculated in terms of polystyrene by an association chromatography (GPC).

  The amorphous PEI polymer may contain an antioxidant, a radical inhibitor, a matting agent, an ultraviolet absorber, a flame retardant, an inorganic substance, other polymers, etc., as long as the effects of the present invention are not impaired. Good. Specific examples of such inorganic substances include carbon nanotubes, fullerenes, carbon black, graphite and other carbides; silicic acids such as talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, silica, bentonite, and alumina silicate. Metal oxides such as silicon oxide, magnesium oxide, alumina, zirconium oxide, titanium oxide and iron oxide; carbonates such as calcium carbonate, magnesium carbonate and dolomite; sulfates such as calcium sulfate and barium sulfate; calcium hydroxide, Hydroxides such as magnesium hydroxide and aluminum hydroxide; glass beads, glass flakes, glass powder, ceramic beads, boron nitride, and silicon carbide are used.

  Specific examples of other polymers include polyamide, polybutylene terephthalate, polyethylene terephthalate, modified polyphenylene ether, polysulfone, polyethersulfone, polyallylsulfone, polyketone, polyarylate, liquid crystal polymer, polyetherketone resin, polythioether. Ketones, polyether ether ketones, polyimides, polyamideimides, tetrafluoropolyethylenes, polycarbonates and the like can be mentioned.

(Method for producing amorphous polyetherimide fiber)
In the production of the amorphous PEI fiber used in the present invention, a known melt spinning apparatus can be used. That is, it can be obtained by melting and kneading amorphous PEI polymer pellets with a melt extruder, introducing the molten polymer into a spinning cylinder, measuring it with a gear pump, and winding the yarn discharged from the spinning nozzle. As described above, when the amorphous polymer is stretched, the shrinkage at a high temperature increases. Therefore, the PEI fiber of the present invention winds the yarn discharged from the spinning nozzle as it is without stretching, It is preferable to use as a spun yarn. The take-up speed at that time is not particularly limited, but it is not preferred if molecular orientation occurs on the spinning line, and it is preferably taken in the range of 500 m / min to 4000 m / min. If it is less than 500 m / min, it is not preferable from the viewpoint of productivity. On the other hand, if it exceeds 4000 m / min, not only the molecular orientation that causes shrinkage at high temperatures proceeds, but also fiber breakage tends to occur. There is a fear.
Further, the amorphous PEI fiber is not particularly limited with respect to the cross-sectional shape of the fiber at that time, and may be circular, hollow, or an atypical cross section such as a star shape.

(Physical properties of amorphous polyetherimide fiber)
The amorphous PEI fibers obtained as described above may have, for example, a dry heat shrinkage of 5.0% or less at 200 ° C., specifically, all the temperatures from 100 to 200 ° C. In the temperature range, the dry heat shrinkage is preferably -1.0 to 5.0%. If the dry heat shrinkage rate exceeds 5.0%, the dimensional change of the product at the time of processing or use may increase. On the other hand, the same reason exists even if it is less than -1.0%. More preferably, the dry heat shrinkage is -1.0 to 4.5%, and more preferably 0 to 4.0%. The dry heat shrinkage referred to here is a value measured by the method described later.

  The amorphous PEI fiber obtained as described above preferably has a fiber strength at room temperature of 2.0 cN / dtex or more. When the fiber strength is less than 2.0 cN / dtex, it is not preferable because the process passability in making a fabric such as paper, non-woven fabric, or woven fabric may be deteriorated or usage may be restricted. More preferably, it is 2.3 to 4.0 cN / dtex, and further preferably 2.5 to 4.0 cN / dtex.

  Further, the fineness of the amorphous PEI fiber of the present invention is not particularly limited as long as it can be subjected to a papermaking process. For example, the single fiber fineness may be about 0.1 to 5.0 dtex, It may be 3.0 dtex or less, more preferably 2.6 dtex or less (for example, 0.1 to 2.3 dtex). Amorphous PEI fibers with such single fiber fineness reduce the porosity of the paper-made flame retardant paper, flame retardant paper with heat resistance, flame retardant, low smoke generation, electrical insulation, etc. Can be advantageously used.

  Furthermore, the fiber length is preferably about 0.5 to 15 mm, more preferably about 1.0 to 12 mm. If the fiber length is too short, the mechanical properties of the paper may not be sufficient. On the other hand, if the fiber length is too long, the fiber opening property, dispersibility, etc. will deteriorate and the uniformity as paper will be impaired. There is a fear.

(Heat resistant fiber)
The heat-resistant fiber used in the present invention is an organic or inorganic heat-resistant fiber having a melting point or a thermal decomposition temperature of 200 ° C. or higher. In combination with the amorphous PEI fiber, the heat-resistant fiber and the heat-resistant fiber are made flame retardant paper. There is no particular limitation as long as it can be applied, and various organic fibers and inorganic fibers can be used. These heat resistant fibers may be used alone or in combination of two or more.

  For example, examples of inorganic fibers include glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, ceramic fibers, and various metal fibers (for example, gold, silver, copper, iron, nickel, titanium, stainless steel, etc.). .

  Examples of organic fibers include wholly aromatic polyester fibers, polyphenylene sulfide fibers, para-aramid fibers, polysulfonamide fibers, phenol resin fibers, polyimide fibers, fibers made of heat-resistant polymers such as fluorine fibers, and the like. Can do.

  Among these heat-resistant fibers, from the viewpoint of improving various physical properties (flame retardant, heat resistance, etc.) of the obtained paper, wholly aromatic polyester fibers, glass fibers, polyphenylene sulfide fibers, para-aramid fibers, polysulfonamides Fibers and the like are preferred, and from the viewpoint of reducing the moisture balance, more preferred are wholly aromatic polyester fibers and glass fibers. Particularly preferred are wholly aromatic polyester fibers from the viewpoint of improving the strength of flame retardant paper.

The wholly aromatic polyester polymer is obtained by polymerizing from an aromatic diol, aromatic dicarboxylic acid, aromatic hydroxycarboxylic acid, etc. Among them, a melt anisotropic polyester exhibiting optical anisotropy when melted is preferable. . The melt-anisotropic polyester referred to in the present invention is an aromatic polyester that exhibits optical anisotropy (liquid crystallinity) in the melt phase. For example, a sample is placed on a hot stage and heated in a nitrogen atmosphere, and the light transmitted through the sample is transmitted. It can be recognized by observing
For example, such a melt anisotropic polyester fiber is marketed as “Vectran (registered trademark)” by Kuraray Co., Ltd.

(Physical properties of heat-resistant fiber)
The heat resistant fiber of the present invention needs to have a melting point or a thermal decomposition temperature of 200 ° C. or higher. In addition, melting | fusing point here is based on JISK7121 test method, is measured with a differential scanning calorimeter (DSC), and is the main absorption peak temperature observed. The thermal decomposition temperature is the temperature at which a part of the heat resistant fiber disappears by decomposition, evaporation or sublimation by applying heat to the heat resistant fiber, and the weight of the resin is reduced by 5%. Say.

Depending on the type of heat-resistant fiber, its physical properties vary, but from the viewpoint of improving the strength of flame retardant paper, the strength of the heat-resistant fiber may be, for example, 3 cN / dtex or more, preferably 4 cN / dtex or more, more preferably 7 cN / dtex or more, and particularly preferably 10 cN / dtex or more. Although the upper limit is suitably determined according to the kind of heat resistant fiber, for example, 40 cN / dtex or less may be sufficient.
The elastic modulus of the heat resistant fiber is preferably, for example, 50 cN / dtex or more, and more preferably 100 cN / dtex or more. Although the upper limit is suitably determined according to the kind of heat resistant fiber, for example, it may be 1500 cN / dtex or less.

  In addition, the fineness of the heat-resistant fiber used in the present invention is not particularly limited as long as it can be subjected to a papermaking process. For example, the single fiber fineness may be about 0.1 to 5.0 dtex, preferably May be 3.0 dtex or less, more preferably 2.6 dtex or less (for example, 0.1 to 2.3 dtex).

  Further, the fiber length of the heat resistant fiber is preferably about 0.5 to 12 mm, more preferably about 1 to 6 mm. If the fiber length is too short, the mechanical properties of the paper may not be sufficient. On the other hand, if the fiber length is too long, the fiber opening property, dispersibility, etc. will deteriorate and the uniformity as paper will be impaired. There is a fear.

(Method for producing heat-resistant flame-retardant paper)
The heat-resistant flame retardant paper of the present invention can usually be suitably produced by a wet papermaking method. In the wet papermaking method, an aqueous slurry containing the amorphous PEI fibers and wholly aromatic polyester fibers is prepared, and the slurry is then subjected to a normal papermaking process. The aqueous slurry may contain a binder (for example, a water-soluble polymer fiber such as polyvinyl alcohol fiber, a heat-adhesive polymer fiber such as polyethylene terephthalate fiber (PET fiber)), and the like. In addition, you may perform a beating process with respect to the fiber used as needed.
Moreover, in order to improve the uniformity and press-fit property of paper, you may add a hot press process after a wet papermaking process.

  Unless the effects of the present invention are impaired, the heat-resistant flame retardant paper of the present invention is made of other fibers; paper strength improvers, fixing agents, antifoaming agents, dyes, ultraviolet absorbers, flame retardants, etc. Various additives; various fillers such as talc, kaolin, calcium carbonate, and titanium dioxide may be included. These raw materials are often added to the aqueous slurry, but may be appropriately attached by coating or the like.

  For example, as other fibers that can be used in combination, in addition to general-purpose fibers such as polyolefin fibers, polyester fibers, polyamide fibers, cellulose fibers, polysulfone fibers, aromatic para-aramid, polyaryl ketone fibers, poly Other heat resistant fibers such as sulfone fibers can be mentioned.

In the heat-resistant flame retardant paper of the present invention, it can be appropriately selected according to the type of heat-resistant fiber. For example, the ratio of the amorphous PEI fiber fiber (A) and the heat-resistant fiber (B) ( Mass ratio) may be included at a ratio (mass ratio) of (A) / (B) = 30/70 to 98/2, preferably 35/65 to 90/10, more preferably 40/60. ~ 85/15.
If the ratio of amorphous PEI fibers is too small, sufficient flame retardancy may not be imparted, while if the ratio of heat resistant fibers is too small, sufficient heat resistance may not be imparted.

  In addition, the ratio of the total amount of the amorphous PEI fibers and the heat-resistant fibers in the heat-resistant flame-retardant paper of the present invention may be, for example, 50 to 100% by mass from the viewpoint of flame retardancy and heat resistance. , Preferably 55 to 98% by mass, and more preferably 60 to 95% by mass.

  Moreover, when a binder is included, the ratio of the binder to 100 parts by mass of the total amount of the amorphous PEI fibers and wholly aromatic polyester fibers may be 3 to 100 parts by mass, preferably 5 to 80 parts by mass. It may be.

(Heat resistant flame retardant paper)
The heat-resistant flame retardant paper of the present invention thus obtained not only has excellent heat resistance and flame resistance, but also has a low equilibrium moisture content and can be suitably used for various applications such as electrical and electronic parts. It is.

  For example, the heat-resistant flame retardant paper of the present invention has a low water content, and its equilibrium moisture content is, for example, 3.0% or less (for example, 0.01 to 2.8%), preferably 2.0% or less. More preferably, it may be 1.0% or less. In addition, the equilibrium moisture content here is a value measured by the method described in the Example mentioned later.

  The heat-resistant flame retardant paper of the present invention is excellent in flame retardancy. For example, the carbonization length according to JIS L1091 A-4 method is, for example, 10.0 cm or less (for example, 1.0 to 9.5 cm), preferably May be 7.0 cm or less, more preferably 6.0 cm or less. In addition, the carbonization length here is a value measured by the method described in the examples described later.

  The heat-resistant flame retardant paper of the present invention has a dry heat shrinkage rate at 200 ° C. of, for example, 4.0% or less, and specifically, has a dry heat shrinkage rate in all temperature ranges from 100 to 200 ° C. -1.0 to 3.5% is preferable. More preferably, the dry heat shrinkage at 200 ° C. may be −1.0 to 3.0%, more preferably 0 to 2.5%. In addition, the dry heat shrinkage here is a value measured by the method described in the Example mentioned later.

  The thickness of the heat-resistant flame retardant paper of the present invention can be appropriately set according to its use and is not particularly limited, and can be selected from a wide range such as about 0.01 to 1 mm. However, the thickness at which the heat-resistant flame retardant paper of the present invention can exhibit excellent heat resistance and flame retardancy may be, for example, 0.1 mm or less.

Further, the basis weight of the heat-resistant flame retardant paper of the present invention may be, for example, about 10 to 150 g / m ² depending on the ratio of the fibers, and more preferably 100 g / m ² or less from the viewpoint of weight reduction. It may be.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this Example. In the following examples, the physical properties of the polymer and paper were measured by the following methods.

[Molecular weight distribution Mw / Mn]
The molecular weight distribution of the sample was measured using water permeation gel permeation chromatography (GPC) and 1500 ALC / GPC (polystyrene conversion). A sample was dissolved so as to be 0.2% by mass using chloroform as a solvent, and then filtered and used for measurement. The molecular weight distribution (Mw / Mn) was determined from the ratio of the obtained weight average molecular weight (Mw) and number average molecular weight (Mn).

[Fiber strength and elastic modulus cN / dtex]
In accordance with JIS L1013 test method, breaking strength and elastic modulus (initial tensile resistance) of pre-humidified yarn under the conditions of a test length of 20 cm, an initial load of 0.25 cN / dtex and a tensile speed of 50% / min. And an average value of n = 20 was adopted. The fiber fineness (dtex) was determined by a mass method.

[Dry heat shrinkage%]
The fiber length after the fiber cut into 10 cm, or the fabric made of the fiber cut into a 10 cm square is held for 10 minutes in an air thermostat kept at 200 ° C. without fixing the end, or the fabric length (Xcm ) Using the following formula:
Dry heat shrinkage (%) = < (10− X ) / 10> × 100

[Carbonization length cm]
Measured according to JIS L1091 A-4 test method, the carbonization length when heated for 3 seconds with a Bunsen burner 17 mm away from the lower end of the sample with respect to the lower end of the vertically arranged sample, n = 5 The average value was adopted.

[Equilibrium moisture percentage]
In accordance with JIS L1013, after the sample was completely dried in an atmosphere of 120 ° C., it was adjusted at a temperature of 20 ° C. and a relative humidity of 65% RH for 72 hours, and the moisture content contained in the sample with respect to the mass of the sample in the completely dried state Was calculated and expressed as a percentage (%).

(Reference example: Production of amorphous PEI fiber)
(1) An amorphous PEI polymer (“ULTEM 9001” manufactured by Servic Innovative Plastics) having a weight average molecular weight (Mw) of 32000, a number average molecular weight (Mn) of 14500, and a molecular weight distribution of 2.2 is 150 ° C. Vacuum dried for 12 hours.

(2) The polymer of (1) above was discharged from a round hole nozzle under the conditions of a spinning head temperature of 390 ° C., a spinning speed of 2000 m / min, and a discharge rate of 50 g / min, and a 220 dtex / 100 f multifilament (single fiber fineness: 2. 2 dtex, strength: 2.6 cN / dtex, dry heat shrinkage at 200 ° C .: 3.5%).
The obtained filament was cut into a fiber length of 10 mm to obtain amorphous polyetherimide short fibers.

Example 1
30 parts by mass of amorphous polyetherimide fiber obtained in Reference Example, fully aromatic polyester fiber (manufactured by Kuraray Co., Ltd., “Vectran”, single fiber fineness: 2.8 dtex, fiber length: 5 mm, melting point: 370 ° C, strength: 23 cN / dtex, elastic modulus: 530 cN / dtex 45 parts by weight, binder fiber (manufactured by Kuraray Co., Ltd., “EP101; polyester binder fiber”, single fiber fineness: 1.5 dtex, fiber length: 5 mm ) Wet paper was made using 25 parts by mass to produce paper with a basis weight of 80 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Examples 2 to 6)
Except that the ratio of the amorphous polyetherimide fiber, the wholly aromatic polyester fiber, and the binder fiber used in Example 1 is the ratio described in Table 1, wet papermaking is performed in the same manner as in Example 1, Paper having a basis weight of 40 g / m ² was produced. Table 1 shows the physical properties of the obtained paper.

(Example 7)
40 parts by mass of amorphous polyetherimide fiber used in Example 1, 20 parts by mass of wholly aromatic polyester fiber, binder fiber (manufactured by Kuraray Co., Ltd., “VP105; polyvinyl alcohol-based binder fiber”, single fiber fineness : 1.5 dtex, fiber length: 3 mm) using 30 parts by mass of paper, wet paper making was performed to produce a paper with a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Example 8)
90 parts by mass of amorphous polyetherimide fiber used in Example 1, 3 parts by mass of wholly aromatic polyester fiber, binder fiber (manufactured by Kuraray Co., Ltd., “VP105; polyvinyl alcohol-based binder fiber”, single fiber fineness : 1.5 dtex, fiber length: 3 mm) using 7 parts by mass of paper, wet paper making was performed to produce a paper with a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

Example 9
Instead of the wholly aromatic polyester fiber used in Example 1, polyphenylene sulfide fiber (manufactured by Toray Industries, Inc., “Torcon”, single fiber fineness: 4.0 dtex, fiber length: 6 mm, melting point: 285 ° C., strength: 4 cN / Dtex, elastic modulus: 60 cN / dtex), and wet papermaking was performed in the same manner as in Example 3 to produce a paper having a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Example 10)
In place of the wholly aromatic polyester fiber used in Example 1, glass fiber (manufactured by Central Glass Co., Ltd., “ECS03-350”, single fiber fineness: 2.0 dtex, fiber length: 3 mm, melting point:> 500 ° C., Wet papermaking was performed in the same manner as in Example 3 except that strength: 1 cN / dtex, elastic modulus: 20 cN / dtex), and paper having a basis weight of 40 g / m ² was produced. Table 1 shows the physical properties of the obtained paper.

(Example 11)
Instead of the wholly aromatic polyester fiber used in Example 1, para-aramid fiber (manufactured by Toray Industries, Inc., “Kevlar 49”, single fiber fineness: 1.7 dtex, fiber length: 6 mm, thermal decomposition temperature: 490 ° C., strength Except for using 20 cN / dtex and an elastic modulus of 741 cN / dtex), wet papermaking was performed in the same manner as in Example 3 to prepare a paper having a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Example 12)
60 parts by mass of amorphous polyetherimide fiber used in Example 1, para-aramid fiber (manufactured by Toray Industries, Inc., “Kevlar 49”, single fiber fineness: 1.7 dtex, fiber length: 6 mm, thermal decomposition temperature: 490 Wet paper making was performed using 40 parts by mass at 20 ° C., strength 20 cN / dtex, and elastic modulus 741 cN / dtex) to prepare a paper having a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Example 13)
80 parts by mass of amorphous polyetherimide fiber used in Example 1, cellulose fiber (manufactured by Daiwabo Rayon Co., Ltd., “raw cotton for wet nonwoven fabric”, single fiber fineness: 1.3 dtex, fiber length: 3 mm, thermal decomposition (Temperature: 310 ° C., strength: 2.0 N / dtex, elastic modulus: 80 cN / dtex) 20 parts by mass was used for wet paper making to prepare a paper with a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Example 14)
40 parts by mass of amorphous polyetherimide fiber used in Example 1, polysulfonamide fiber (manufactured by Shanghai TNLON, “TANLON”, single fiber fineness: 1.2 dtex, fiber length 3 mm, thermal decomposition temperature: 490 ° C. Strength: 3.0 cN / dtex, elastic modulus: 70 cN / dtex 20 parts by mass, binder fiber (manufactured by Kuraray Co., Ltd., “VP105; polyvinyl alcohol binder fiber”, single fiber fineness: 1.5 dtex, fiber length: 3 mm) and 30 parts by mass of wet paper making to produce a paper with a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Comparative Example 1)
Using 50 parts by mass of the amorphous polyetherimide fiber used in Example 1 and 50 parts by mass of the binder fiber used in Example 1, wet papermaking was performed to prepare a paper having a basis weight of 40 g / m ² . Table 1 shows the physical properties of the obtained paper.

(Comparative Example 2)
40 parts by mass of amorphous polyetherimide fiber used in Example 1 and polyethylene fiber (Toyobo Co., Ltd., “Dyneema”, single fiber fineness: 1.5 dtex, fiber length: 3 mm, melting point 140 ° C.) 40 Wet paper is made using 20 parts by mass of a binder and a binder fiber (manufactured by Kuraray Co., Ltd., “VP105; polyvinyl alcohol-based binder fiber”, single fiber fineness: 1.5 dtex, fiber length: 3 mm), and the basis weight is 40 g. / M ² paper was produced. Table 1 shows the physical properties of the obtained paper.

(Comparative Example 3)
The physical properties of commercially available meta-aramid heat resistant paper (manufactured by DuPont, “Nomex paper”) were measured in the same manner as in Examples, and the physical properties are shown in Table 1.

(Comparative Example 4)
Commercially available cellulose heat-resistant paper (manufactured by Daiwabo Rayon Co., Ltd., “raw cotton for wet nonwoven fabric”, single fiber fineness: 1.3 dtex, fiber length: 3 mm, thermal decomposition temperature: 310 ° C., strength 2.0 cN / dtex, elastic modulus: 80 cN / dtex), the physical properties were measured in the same manner as in the Examples, and the physical properties are shown in Table 1.

  As is clear from Table 1, the heat-resistant flame retardant paper obtained in Examples 1 to 14 is composed of specific amorphous PEI fibers and heat-resistant fibers. Not only was the shrinkage at ℃ low, but the equilibrium moisture content of the paper could be kept at a low level.

  Various heat-resistant fibers were found to be able to impart flame resistance to heat-resistant flame-retardant paper by combining with amorphous PEI fibers, but especially melt anisotropic fully aromatic polyester fibers and glass fibers are flame retardant. It was preferred because of its properties, heat resistance and low moisture content.

  Moreover, the flame retardant property is good when the total amount of the amorphous PEI fiber and the heat resistant fiber is 70 parts by mass or more in the entire heat resistant flame retardant paper, and particularly high flame retardant at 70 to 90 parts by mass. Showed sex. Moreover, the shrinkage rate at 200 ° C. tended to decrease as the ratio of heat resistant fiber to amorphous PEI fiber increased.

  On the other hand, Comparative Example 1 does not have sufficient heat resistance because it does not have heat-resistant fibers even if specific amorphous PEI fibers are used, so that the carbonization length becomes long and sufficient flame retardancy cannot be exhibited. . Further, in Comparative Example 2, even though amorphous PEI fibers were used, they were not combined with heat resistant fibers, so that although the amorphous PEI fibers were present compared to Example 1, it was obtained. The obtained paper not only has a long carbonization length, but also has poor heat resistance.

  Moreover, although the meta-aramid heat-resistant paper currently on the market has flame retardancy, the equilibrium moisture content has not been suppressed. Moreover, the commercially available cellulose heat-resistant paper did not have flame retardancy and not only burned but also its equilibrium moisture content remained high.

  The heat-resistant flame retardant paper of the present invention is not only excellent in flame retardancy and heat resistance, but also has a low equilibrium moisture content, so that it can be maintained at a low level of industrial moisture, electrical and electronic fields, agricultural materials, optical materials, and aircraft. -It can be used very effectively for many applications including the automobile and marine fields. For example, it can be used effectively as an insulating material for various transformers and voltage cables, a printed wiring board, and the like.

  As described above, the preferred embodiments of the present invention have been described. However, various additions, modifications, or deletions are possible without departing from the spirit of the present invention, and such modifications are also included in the scope of the present invention. It is.

Claims (6)

An amorphous polyetherimide fiber (A) formed from an amorphous polyetherimide polymer having a molecular weight distribution (Mw / Mn) of less than 2.5;
A heat-resistant flame-retardant paper comprising a heat-resistant fiber (B) composed of a melt-anisotropic wholly aromatic polyester fiber and having a carbonization length of 10.0 cm or less according to JIS L1091 A-4 method.   The heat resistance according to claim 1, wherein the ratio (mass ratio) of the amorphous polyetherimide fiber (A) and the heat resistant fiber (B) is (A) / (B) = 30/70 to 98/2. Flame retardant paper.   The heat resistant flame retardant paper according to claim 1 or 2, wherein the total amount (A + B) of the amorphous polyetherimide fiber (A) and the heat resistant fiber (B) is 50% by mass or more of the heat resistant flame retardant paper.   The heat-resistant flame retardant paper according to any one of claims 1 to 3, wherein the equilibrium moisture content is 3.0% or less.   The heat-resistant flame-retardant paper according to any one of claims 1 to 4, wherein a dry heat shrinkage rate at 200 ° C is 4.0% or less. The binder according to any one of claims 1 to 5 , further comprising a binder, and 3 to 100 masses of the binder with respect to 100 mass parts of the total amount of the amorphous polyetherimide fiber and the melt anisotropic fully aromatic polyester fiber. Heat-resistant flame retardant paper containing parts.