JPS62115040A - Wholly aromatic polyamide molding having hydrophobic surface and production thereof - Google Patents

Abstract

PURPOSE:To obtain a molding having a hydrophobic surface, a low moisture absorption ratio and a low moisture absorption expansion ratio, by crosslinking and substituting the N-position of amide groups on the surface of a wholly arom. polyamide molding to coat said surface with an N-crosslinked, substd. wholly arom. polyamide. CONSTITUTION:A molding of a wholly arom. polyamide having repeating units of the formula -NH-Ar, -NH-CO-Ar2-CO- and/or the formula -NH-Ar3- CO-(wherein Ar1, Ar2, Ar3 are each a bivalent arom. ring group) (e.g., woven fabric) is reacted with an alkali metal or alkaline earth metal compd. to convert part or the whole of the amide linkages on the surface of the molding into N-metal salt. The surface thereof is then reacted with a halogen compd. having a double bond or a triple bond (e.g., allyl bromide) to introduce side chains having a double bond or a triple bond. The side chains are crosslinked and polymerized with a Michael acceptor (e.g., trifluoroethyl methacrylate) to obtain the titled molding.

Description

Detailed Description of the Invention [Technical Field of Application of the Invention] The present invention relates to a surface-hydrophobic wholly aromatic polyamide molded article and a method for producing the same. The present invention relates to a wholly aromatic polyamide molded article whose surface is made hydrophobic, and a method for producing the same.

[Prior art]

As a heat-resistant polymer, molded products such as fibers and films made of so-called fully aromatic polyamides, in which all of the divalent hydrocarbon groups bonded through amide bonds are aromatic cyclic groups, have high strength and high strength. It is useful in a variety of applications because of its elastic modulus and excellent heat resistance. In particular, such fibers are added to various thermoplastic resins, rubbers, and thermosetting resins as strong fibers due to their properties of high strength and high elastic modulus, and the mechanical properties, heat resistance, etc. of the compositions have been studied. has been done. (For example, Polymer Engineering and Science No. 14
1, p. 633 (1974), Journal Op Applied Polymer Science Vol. 20, p. 435 (197
6), Rubber Chemistry and Technology
(Refer to Vol. 50, p. 945 (1977)) [Problems to be Solved by the Invention] However, wholly aromatic polyamides generally have large moisture absorption and dimensional changes due to the hydrogen bonds between the amide groups of the polyamide. For example, a wholly aromatic polyamide film has a hygroscopic expansion rate that is ten times or more greater than that of a polyimide film.

Journal op Polymer Science, Polymer
Chemistry Edition No. 1941) p. 33 (1)
981) discloses a technique for substituting fully aromatic polyamide with N-alkyl in dimethyl sulfoxide, which is expected to reduce the moisture absorption rate or improve moisture absorption stability. When the surface of a group polyamide molded product is modified to N-metalized wholly aromatic polyamide and N-alkylated wholly aromatic polyamide, which are intermediates of this method, the molded product has poor chemical resistance. It has been found that if the surface of the material is damaged or a dense layer is present on the surface, it will be destroyed, and therefore a reduction in moisture absorption rate and an improvement in moisture absorption stability will not be realized. In addition, heat treatment of wholly aromatic polyamide is disclosed in JP-A-47-43419, etc., which increases crystallinity,
It is conceivable that the moisture absorption properties will improve accordingly,
The degree of this is very small, and there are also drawbacks such as the wholly aromatic polyamide becoming brittle.

[Means for solving problems]

In order to solve the above-mentioned problem, the present inventors have conducted extensive research and found that the above-mentioned problem can be solved by subjecting the surface of a wholly aromatic polyamide molded product to cross-linking polymerization using a Michael acceptor. We have arrived at the present invention.

That is, the present invention provides repeating units of the general formula -NHArt -NHCOArz CO- and/or NH-Ari co- (wherein Arl, Art, Ar:+ each independently represent a divalent aromatic cyclic group) A wholly aromatic polyamide molded article having a surface hydrophobic wholly aromatic polyamide having a surface partially or entirely covered with an N-crosslinked substituted wholly aromatic polyamide obtained by crosslinking and polymerizing a Michael acceptor from an amide group. It is a group polyamide molded product, and has the general formula -N)I Ar
t NHCOArz CO- and/or N
HAr=co- repeating unit (Ar+, A
rz and Ar3 each independently represent a divalent aromatic cyclic group) is reacted with an alkali metal compound or an alkaline earth metal compound to form an amide on the surface of the polyamide. Part or all of the bonds are made into N-metal salts, then reacted with a halogen compound containing a double bond or triple bond, and the side chain having a double bond or triple bond is further introduced into the surface of the polyamide. The present invention is a method for producing a surface-hydrophobic wholly aromatic polyamide molded article, which comprises cross-linking polymerizing a Michael acceptor.

In the wholly aromatic polyamide used in the present invention, at least 85 mol% or more of the amide bonds are obtained from aromatic cyclic diamine and aromatic cyclic dicarboxylic acid components. Examples of its structure include polyparabenzamide, polyparaphenylene terephthalamide, poly-4,4'-diaminobenzanilide terephthalamide, polyparaphenylene-2
, 6-naclic amide, copolyparaphenylene/4
．． 4' (3゜3゛-dimethylbiphenylene)-terephthalamide, copolyparaphenylene/2,5-pyridylene-terephthalamide, polyorthophenylenephthalamide, polymetaphenylenephthalamide, polyparaphenylenephthalamide, polyorthophenylene Isophthalamide, polymetaphenylene isophthalamide, polyparaphenylene isophthalamide, polyorthophenylene terephthalamide, polymetaphenylene terephthalamide, poly-1,5-naphthalene phthalamide, poly-4
, 4”-diphenylene-ortho-phthalamide, poly-
4,4°-diphenylene isophthalamide, poly-1,
4-naphthalene phthalamide, poly-1,4-naphthalene isophthalamide, poly-1,5-naphthalene isophthalamide, etc., and compounds in which a part of the benzene nucleus of these aromatic diamines is substituted with halogen, as well as these A part of the benzene nucleus of the aromatic diamine is converted into piperazine, 2
．． Aromatic polyamides containing alicyclic amines, such as compounds substituted with 5-dimethylpiperazine and 2,5-diethylpiperazine, or aromatic diamines such as 3,3'-oxydiphenylenediamine, 3,4'- Ether groups such as oxydiphenylenediamine, alkyl groups, -3-, -
Aromatic polyamides containing two phenyl groups linked by groups such as 5O2-+.-C-, -NH-, or copolymers of the above-mentioned aromatic polyamides, such as poly-3,
Examples include 3'-oxydiphenylene terephthalamide/polyparaphenylene terephthalamide copolymer, poly-3,4'-oxydiphenylene terephthalamide/polyparaphenylene terephthalamide copolymer, and the like.

The wholly aromatic polyamide used in the present invention can be in various forms and is not particularly limited, such as fibers (multifilament, staple fiber, chopped strand, monofilament), fibrid, film, woven fabric, non-woven fabric. , sheet, paper, powder, etc. Particularly preferred are fibers, films, and woven fabrics. There are no particular limitations on the method for producing these molded articles from wholly aromatic polyamide in carrying out the present invention.

Examples of the alkali metal compound or alkaline earth metal compound used in the present invention include sodium hydride,
Examples include sodium methoxide, sodium ethoxide, potassium hydride, botanical methoxide, botanical ethoxide, butyllithium, Grignard reagent, calcium hydride, sodium hydroxide, potassium hydroxide, calcium hydroxide, and the like.

In the present invention, a solvent is preferably used in the reaction in which a wholly aromatic polyamide molded article is reacted with an alkali metal compound or an alkaline earth metal compound to convert some or all of the amide bonds on the surface of the polyamide into an N-metal salt. The solvent used is dimethyl sulfoxide, N, N
-dimethylformamide, methanol, ethanol ether, benzene, hexane, etc., and particularly preferred are aprotic polar solvents such as dimethyl sulfoxide and N,N-dimethylformamide.

Examples of the halogen compound containing a double bond or triple bond used in the present invention include allyl bromide, 1-bromo-2-butene, 1-bromo-3-butene, crotyl bromide, propargyl bromide, l-bromo-2-butyne, l-bromo-3-butyne, allyl chloride, 1-chloro-2-butene, 1-chloro-3-butene, crotyl chloride, propargyl chloride, l-chloro-2-
Butyne, 1-chloro-3-butyne, allyl iodide, 1-iodo-2-butene, l-iodo-3-butene,
Crotyl iodide, propargyl iodide, 1
-iodo-2-butyne, 1-iodo-3-butyne and the like.

In the present invention, the above-mentioned wholly aromatic polyamide in which part or all of the amide bonds are N-metal salts can be used as a double bond or a triple bond.
In the treatment of reacting with a halogen compound containing a heavy bond, it is preferable not to use a solvent, but it is also possible to use an organic solvent such as ether, methylene chloride, etc.

The Michael acceptor used in the present invention includes styrene, acrylic esters, methacrylic esters, acrolein, methacrolein, acrylamide, methacrylic amide, acrylonitrile, methacrylonitrile, etc., which increase hydrophobicity. Particularly preferred are trifluoroethyl methacrylate, 2.2.3.3-tetrafluoropropyl methacrylate, 2.2.3,4,4.4-hexafluorobutyl methacrylate, perfluorooctylethyl methacrylate, It is an α,β-unsaturated ester having a fluorine atom in the ester group, such as perfluorooctylethyl acrylate.

The amount of Michael acceptor to polyamide in the present invention is not particularly limited, as long as the Michael acceptor covers the surface of the polyamide.

In the present invention, in order to further improve the degree of crosslinking in the reaction of crosslinking a Michael acceptor to a side chain having a double bond or triple bond introduced on the surface of the polyamide, divinylbenzene or divinylketone is used as a representative example. It is also possible to coexist with a compound having a polyvalent unsaturated group, and this is actually more preferable. Further, in this crosslinking polymerization reaction, it is preferable to use azobisisobutyronitrile, benzoyl peroxide, or the like as an initiator.

In the present invention, it is preferable not to use a solvent in the reaction of crosslinking and polymerizing a Michael acceptor to a side chain having a double bond or triple bond introduced into the polyamide surface, but an organic solvent such as ether, methylene chloride, etc. It is also possible to use the following.

The alkali metal compound or alkaline earth metal compound used in the present invention, the halogen compound containing a double bond or triple bond, the Michael acceptor, and the solvent used in each reaction step may be purified, dehydrated, etc. if necessary. It is preferable to use it after pretreatment, and it is also possible to include other solvents that do not inhibit the reaction.

There are no particular restrictions on the temperature and time of the N-metalation reaction, and generally the reaction temperature is between about 0.degree. C. and the boiling point of the system, particularly preferably between 5.degree. C. and 100.degree. Approximately 1 second to 5 hours is appropriate.

There is no particular restriction on the concentration of the N-metalation reaction, and it is particularly preferably 0.01 mol/l-0.1 mol.
/ 1.

There are no particular restrictions on the temperature and time of the N-substitution reaction using a halogen compound containing a double bond or triple bond, and the reaction temperature is generally between about 0°C and the boiling point of the halogen compound, particularly preferably A temperature between 20° C. and 100° C. is used, and a suitable reaction time is about 1 second to 10 hours.

There are no particular limitations on the concentration of the N-substitution reaction using a halogen compound containing a double bond or triple bond, and a method that does not use a solvent is particularly preferred.

There are no particular limitations on the temperature and time of the crosslinking reaction using a Michael acceptor, and generally the reaction temperature is between about 12°C and the boiling point of the Michael acceptor, particularly preferably between 40°C and 200°C. The appropriate reaction time is about 1 second to 10 hours. Further, in this crosslinking reaction, it is also possible to irradiate with light such as ultraviolet rays or radiation.

The molded product after the crosslinking reaction may be subjected to treatments such as washing with an organic solvent such as acetone and drying, if necessary.

The wholly aromatic polyamide molded article of the present invention produced in this way has a surface layer of about 0.1 to several μm in part or all.
m depth, undergoing N-crosslinking reaction. Therefore, the molded article of the present invention has repeating units of the general formula -NHAr+ NHCO-^rg -co- and/or -NH-Arz-co- (wherein Ar+, Art, and Ar3 each independently represent a divalent A part or all (preferably all) of the surface of the wholly aromatic polyamide molded product having (representing an aromatic cyclic group) is formed by cross-linking polymerization of a Michael acceptor from an amide group.
- It will be covered with a cross-linked substituted wholly aromatic polyamide.

N-substituent on the surface of wholly aromatic polyamide molded product, or N
- Cross-linking substituents can be detected by infrared absorption spectroscopy, ATR method, electrochemical analysis electron spectroscopy (ESCA), water contact angle measurement, etc.; Even if it is etched with a solvent that can be etched, if crosslinking polymerization has occurred, it can be confirmed by remaining undissolved.

〔Effect of the invention〕

The feature of the surface-hydrophobic wholly aromatic polyamide molded article of the present invention is that the hygroscopicity and hygroscopic expansion rate are reduced due to crosslinking and substitution at the N-position of the amide group on the surface.

This is because the hydrogen bonds of the amide groups of the aromatic polyamide molded article on the surface are destroyed by the N-substitution reaction, and the surface is covered with hydrophobic crosslinking substituents.

In addition, in the present invention, since the surface of the wholly aromatic polyamide molded article is crosslinked, the chemical resistance of this surface crosslinked layer is extremely excellent, and especially in the case of fibers, it is possible to suppress fibrillation. Hydrophobicization can be achieved without sacrificing the inherent properties of wholly aromatic polyamide molded products, such as high strength, high modulus, heat resistance, high tear resistance, and dimensional stability at high temperatures.

〔Example〕

EXAMPLES Hereinafter, the present invention will be described with reference to Examples in order to further clarify the present invention, but it goes without saying that the scope of the present invention is not limited to these Examples.

In the examples, the hygroscopic expansion coefficient is 1
Dry completely at 00℃, cool to room temperature, relative humidity 90%
The elongation was calculated using the following formula by measuring the elongation with a TMA (thermal stress strain measuring device) in an atmosphere of

Example 1 42 mg of sodium hydride (1,0
4 mmol) was washed with a small amount of n-hexane under a nitrogen stream. Next, 25 m 7! of dimethyl sulfoxide was added to this sodium hydride. was added and stirred at room temperature for 10 minutes. Next, the temperature was raised to 70°C, stirred for 30 minutes, and then allowed to cool to room temperature. A poly(p-phenylene terephthalamide) film of 2 cIl length and 2cm width (Japanese Patent Publication No. 57-1
7886 method) for 3 minutes. Next, this film whose surface was N-sodified was immersed in 2 ml of allylpromide for 10 minutes, and after treatment, it was washed with acetone and air-dried. The poly(p-phenylene terephthalamide) film whose surface was N-allylated in this way was
2m7 of styrene containing 5n+g of azobisisobutyronitrile! and reacted at 100° C. for 6 hours.

After the reaction, excess polystyrene was removed with chloroform and air-dried. The hygroscopic swelling rate of the poly(p-phenylene terephthalamide) film treated in this way and whose surface is cross-linked and polymerized with polystyrene is 1, I x 10-'mm/
mm・χR1+, and that of the untreated film (6,
OX 10-'mm/+n+++4R1 () was able to be reduced to about one-sixth. Also, the moisture absorption rate was reduced to about one-tenth.

Example 2 Example 1 was repeated, except that 2 ml of methyl acrylate was used instead of 2 nl of styrene. In this case, the hygroscopic expansion coefficient of the treated film is 2.3X10-'IIIl/
ml1)-χRH, and that of the untreated film (6
, OX 10-5mm/mm4RH), it was possible to suppress dimensional changes due to moisture absorption by about 60%. Also, the moisture absorption rate was reduced to about one-fifth.

Example 3 Instead of 2 ml of styrene, methacrylic acid 2,2.3°3
Example 1 was repeated except that -hexafluorobutyl was used and 0.5 ml of divinylbenzene was present in the crosslinking reaction. In this case, the hygroscopic expansion coefficient of the treated film is 0.6 X 10-'mm/mm-XRH, which is 0.6
m/mr@・χRH), and the dimensional change due to moisture absorption is 1
I was able to reduce it to 1/0. In addition, the moisture absorption rate is approximately 1
It became 1/0.

Example 4 Example 1 was repeated except that wholly aromatic polyamide fibers (thread diameter: 12.1 μm) were used instead of the wholly aromatic polyamide film. In this case, the moisture absorption rate of the treated fiber is
The hygroscopicity was 1.5%, which was about 70% lower than that of untreated fibers (5.0%). Also, the moisture absorption rate is 5
It became 1/1.

Example 5 Example 1 was repeated except that a woven fabric of wholly aromatic polyamide fibers (thread diameter was 12 μm, average of 10 fibers) was used instead of the wholly aromatic polyamide film.

In this case, the moisture absorption rate of the treated fibers is 1.5%,
The hygroscopicity was reduced by approximately 70% compared to that of untreated fiber fabric (5.1%). The moisture absorption rate was also reduced to one-fifth.

Claims (5)

[Claims] (1) General formula -NH-Ar_1-NH-CO-Ar_2
-CO- and/or -NH-Ar_3-CO- repeating unit (wherein Ar_1, Ar_2, Ar_3 are
A wholly aromatic polyamide molded article having N-crosslinked substituted wholly aromatic polyamide molded articles each independently representing a divalent aromatic cyclic group, in which part or all of its surface is crosslinked and polymerized from an amide group to a Michael acceptor. Surface hydrophobic fully aromatic polyamide molded product covered with group polyamide (2) General formula -NH-Ar_1-NH-CO-Ar_2
-CO- and/or -NH-Ar_3-CO- repeating unit (wherein Ar_1, Ar_2, Ar_3 are
A wholly aromatic polyamide molded article having a group (each independently representing a divalent aromatic cyclic group) is reacted with an alkali metal compound or an alkaline earth metal compound, and a part of the amide bond on the surface of the polyamide or All of them are made into N-metal salts, and then reacted with a halogen compound containing a double bond or triple bond, and then a Michael acceptor is added to the side chain having a double bond or triple bond introduced into the surface of the polyamide. A method for producing a surface-hydrophobic wholly aromatic polyamide molded article, characterized by cross-linking polymerization of (3) The molded article according to claim 1, wherein the wholly aromatic polyamide molded article is a wholly aromatic polyamide fiber. (4) The molded article according to claim 1, wherein the wholly aromatic polyamide molded article is a wholly aromatic polyamide woven fabric. (5) The molded article according to claim 1, wherein the wholly aromatic polyamide molded article is a wholly aromatic polyamide film.