AU463539B2 - Melt-spun drawn or undrawn flame-resistant and anti-fusing cured phenolic continuous filament and process for producing said filament - Google Patents

Description

48,16 572 This invention relates to a melt-spun drawn

or undrawn flame-resistant and antifusing cured phenolic

continuous filament having improved yar properties such

as tenacity and elongation, its filamentary structure,

and to a process for producing the filament. Phenolic resins have previously attracted

attention as flame-resistant organic compounds because

of a very high rate of residue after carbonization, and

found a wide variety of application. However, because

of their low degrees of polymerization and poor spin-

nability, it has been extremely difficult to spin these

phenolic resins continuously on a commercial basis. It has recently been proposed to spin an

uncured phenolic resin and curing the melt-spun filament

using a curing agent thereby to produce a flame-resistant

and antifusing cured phenolic resin filament (German

OLS No. 1910419). It was also proposed that in order to impart

a high degree of elastic properties to a polyamide-

filament, a molten mixture of a fusible phenol-

formaldehyde resin and a polyamide resin is melt spun

to produce filaments and the resulting filaments are

cured using an alkali curing agent (Japanese Patent

Publication No. 5927/65 published March 25, 1965). This

Patent Publication discloses that the fusible phenol-

formaldehyde resin can be mixed with the polyamide in

an amount up to 40 o by weight of the polyamide (which

corresponds to 28.6 by weight based on the total weight

of the two resins), and the preferred amount of the fusible

4 63,53 9

4 8,1 6 5 /72 phenol-formaldehyde resin is 5 to 25 by weight based

on the polyamide resin, or 4.8 to 20 based on the weight

of the total weight of the two resins. The Patent points

out that if the amount of the phenol-formaldehyde resin

exceeds 25 by weight based on the polyamide resin,

the spinnability or drawability of the resulting mixture

is reduced, and adverse effects are exerted on the quality

of the resulting filament, and in the sole Example in

this Patent the amount of the phenol-formaldehyde resin

is 10 by weight based on nylon 6. It has also been attempted to impart elastic

properties to a filament of an aliphatic polyamide by melt-spinning a mixture of a fusible cresol-formaldehyde

resin and an aliphatic polyamide (Japanese Patent Publi-

cation No. 4541/68 published February 19, 1968). In

this attempt, no curing step is employed. The Patent

discloses that the fusible cresol-formaldehyde resin

should be mixed in an amount of 0.5 to 20 by weight

based on the weight of the polyamide, and the purpose

of the invention is not achieved if the amount exceeds by weight.

The inventors of this invention noted that the first of the above proposals is quite silent on the incorporation of a thermoplastic resin into a phenolic resin, and that the second and third attempts recommend the incorporation of a phenolic resin in a polyamide resin in an amount not more than 25 by weight. Extensive research and development work on this fact led to the discovery that an aliphatic polyamide resin 463,5 3 9

48.16 5/72 can be blended with uncured novolac resin in an amount of lcss than about 5 1 by weight but not less than 0.1 by weight, preferably not over 4.5 5/ by weight, more preferably 0.5 4 by weight based on the total weight of said two resins, and the resulting blend has good melt- spinnability not seen in the phenolic resin-containing polyamide resin filament mentioned above. It has also been found that when the resulting melt-spun filament is cured with a curing agent in the presence of an acid catalyst, the cured filament has desirable flame-resistant and antifusing properties of a phenolic resin filament, and also has improved properties not attainable by the phenolic resin-containing polyamide resin filament, such as tenacity, elongation, or abrasion resistance. Accordingly, an object of this invention is to provide a melt-spun drawn or undrawn flame-resistant and antifusing cured continuous filament comprising a novolac resin and an aliphatic polyamide resin. Another object of this invention is to provide a process for producing such a filament. A further object of this invention is to provide a filamentary structure or article which contains a filamentary material derived from said melt-spun drawn or undrawn flame-resistant and antifusing cured continuous filament. Many other objects and advantages of this invention will become apparent from the following de- scription. 463,53 9

48,16 572

The filament of this invention which is meant an to include multi-filaments) comprises a novolac resin and blended in aliphatic polyamide resin, said resin being homogeneously the novolac resin. The novolac resin is a resin which is uncured

and fusible in the starting molten mixture, and can be cured after with a curing agent in the presence of an acid catalyst itself is melt-spinning. The method of preparing the novolac resin with an alde- well known. It can be produced by reacting a phenol Usually, hyde under heat in the presence of an acid catalyst. of about 300 novolac resins have a number average molecular weight

to about 2,000. If desired, those having a larger molecular

weight (for example, up to about 5,000) May be used in this

invention. Therefore, as is well known, mainly novolac-type of modified novolac resins obtained by any desired bombination can the novolac-type reaction and the resol-type reaction also be used. Furthermore, any desired combinations of phenols and

aldehydes can be used, and different novolac resins each

derived from a different combination of phenol and aldehyde

can be used conjointly. The phenols used for producing the novolace

resins are most commonly phenol and cresol. But other phenols can z

also be used. Examples of these phenols are phenol, o-cresol,

m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 2,4-xylenol, m-ethylphenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, o-ethylphenol, phenol, p-ethylphenol, p-phenylphenyl, p-tertiary butyl and mixtures of p-tertiary amylphenol, bisphenol, A, resorcinol, tw or more of these with each other.

463,53 9

4 8,1 6 5 /72 The aldehyde most commonly used for polycondensing with the above phenol is formaldehyde, but paraformaldehyde, hexamethylenetetramine, and furfural can also be utilized. The acid catalyst used for the reaction of forming novolac resins may be any known organic or in- organic acids, for example, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, or phthalic acid. The aliphatic polyamide resin which constitutes the other element of the filament of this invention is used in an amount of less than about 5 by weight based on the total weight of the novolac resin and the polyamide resin, the aliphatic polyamide resins are especially preferred in view of their good dispersibility in the novolac resin, good improving effects on the spinnability of the novolac resin, or little likelihood of exerting adverse effects on the flame-resistant and antifusing properties of the novolac resin, etc. Specific examples of the aliphatic polyamide resin that can be used in the invention include polyamide resins such as nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 611, nylon 612, and blends or copolymers of two or more of these with each other. Formaldehyde is most commonly used in the present invention as a curing agent. Other curing agents can also be used, the examples being aldehydes such as paraformaldehyde, hexamethylenetetramine, furfural, chloral, ei glyoxal, and compounds which generate formaldehyde by heating for example, such as trioxane, tetraoxane, or polyoxymethylene. 4 63,5 3 9

4 8,16 5 nz An acid catalyst is used for curing the filament

obtained by this invention. Examples of the acid catalyst

include an organic or inorganic acid described as the

catalyst for forming the novolac resin.

The melt-spun drawn or undrawn flame-resistant

and anti-fusing continuous filament of this invention

comprises the novolac resin described above and the

aliphatic polyamide resin described above, the amount

of the aliphatic polyamide resin being less than about

by weight but not less than 0.1 by weight based

on the total weight of said two resins. The amount of

the synthetic aliphatic polyamide resin is preferably

not over 4.5 by weight, more preferably 0.5 to 4 %96 by

weight based on the total weight of the two resins. The filament described above can be produced by melt-spinning a molten mixture of an uncured novolac resin and an aliphatic polyamide resin in an amount of less than about 5 %96 by weight but not less than 0.1 9% by weight based on the total weight of said two resins, and then curing the melt-spun filament with a curing agent in the presence of an acid catalyst. If the amount of the aliphatic polyamide resin is too small, the spinnability of the molten mixture becomes poor, and the properties of the filament cannot be improved to a satisfactory degree. When the amount is about 3 by weight, the flame-resistant and anti- fusing properties of the filament are maintained at a high level and fine-denifilaments can be obtained by high speed melt-spinning. 463.53 9

48,16 5 /72

The melt-spinning apparatus and operation are in well known, and the description of them will be omitted

this specification. The known treatments, such as filtration or at any time deforming, of the molten mixture can be performed

before the molter mixture reaches the spinneret. time The spun filament can be cured after wind-up or at any

before wind-up. The wind-up rate is usually about 200 to 2500 faster meters per minute. Usually, wind-up rates somewhat to the than the spinning speed give favorable effects

tenacity of the resulting filament. Known oils, or n-paraffinic hydrocarbons, etc.

can be utilized as spinning oil preparations. The curing of the melt-spin filament can be

Derfor med in various ways at a temperature from room 0 temperature to 250 C. The temperature can be properly to thetype chosen within the above-mentioned range according and amount of the and amount of the novolac resin, the type filament, the way aliphatic polyamide resin, the denier of the and amount of the in which the curidng is performed, the type

curing agent, and the like. In the most general embodiment, the melt-spun

immersed, or caused to run through, a bath containing filament is above and held the cur ing agent and the acid catalyst described temperature, for at toom temperature or temperatures near room 0 The filament is example, 5 to 45 0 preferably 10 to 40 C. for example, gradually heated up to the desired temperature, temperature. to 140 0 preferably 70 to 130°C., and kept at this

The contacting

463,539

48,16 5 n2 between the filament and a liquid containing the curing

agent and the acid catalyst is not limited to the method

described, but other means such as spraying or fuming can also be utilized.

One example of the aqueous liquid of the bath

is a liquid containing the curing agent such as formaldehyde

in an amount of from 12 to 22 by weight, preferably from 16 to 19 by weight and the acid catalyst in an amount of from 12 to 20 by weight, preferably from 16 to 18 %5by weight.

In another embodiment of curing, the filament is treated in a fume or vapor containing formaldehyde

and the acid catalyst.

Preferably, after contacting the melt-spun filament with thecuring agent, the temperature is raised

gradually to the heat-curing temperature. For example, the temperature is raised to the desired point at a rate 0 of about 3 to 20 C./hour from the initiation of heat-

curing. Or the temperature is maintained as low as possible at the initial stage of heat-curing, and sub- stantial raising of the temperature is performed from

the intermediate stage of heat-curing until the final

desired temperature is obtained. Or substantial temperature raising is performed from the initial stage of heat- curing, but the final temperature is held at as low a

temperature as possible and this state is maintained.

After the curing operation, the filament is washed with

water, neutralized with alkali if necessary, and dried to obtain a final filament product.

463.53 9

48,16 5 /72 The heat-curing time is optionally chosen

according to the way in which the curing operation is

performed, the heating temperature, the type and concent-

ration of the curing agent and catalyst, the type and

amount of the novolac resin, the type and amount of the

thermoplastic synthetic resin, the denier of the filament,

etc. Usually, it is about I to 20 hours. If desired,

the heat-curing time can be either shorter or longer.

The melt-spun filament can be drawn at any

desired time before and/or after curing. The drawing

often results in desirable properties of the filament.

The drawing operation may be conducted in one

stage or in more stages, and the filament can be either

cold or hot drawn. In the case of a multi-stage drawing,

cold drawing and hot drawing can be optionally combined.

The draw ratio is also optional, and usually up to

based on the length of an undrawn filament.

The resulting continuous filament of this in-

vention can be directly used in the form of monofilaments,

multifilaments, or tows, but can also be used in the

form of fibers cut to the desired lengths. Or it can

be used as spun yarns either alone or in admixture with

known filaments or fibers, or in the form of twisted

yarns or the like. It can also be made into various

filamentary structures such as knitted or woven fabrics

or non-woven fabrics either alone or in admixture with

known filaments. Accordingly, the present invention

includes within its scope a filamentary structure in

a form selected from the group consisting of fibers,

48.165n2 yarns, knitted fabrics, woven fabrics, non-woven fabrics,

felt or carpets or the like, which contains or consists

of a filamentary material derived from the melt-spun

drawn or undrawn flame-resistant and anti-fusing cured phenolic continuous filament which comprises a novolac

resin and an aliphatic polyamide resin, as hereinabove

described.

The melt-spun drawn or undrawn flame-resistant

and anti-fusing cured phenolic continuous filament has

superior flame-resistant and anti-fusing properties, and

has superior properties such as tenacity, elongation,

or abrasion resistance which are not possesed by the

melt-spun filament of the novolac resin. Moreover, the

molten mixture consisting of the novolac resin and aliphatic polyamide resin shows excellent spinnability not attainable by molten novolac resin. Furthermore, the filament of this invention has outstandingly superior flame-resistant and anti-fusing properties that cannot be attained by a filament consisting of aliphatic polyamide resin or are better than those of the phenolic resin-containing polyamide resin filament containing a novolac resin in an amount of not more than by weight based on the polyamide resin already described. These advantages of this invention will become apparent from the following Examples taken together with the following Comparative Examples. In a preferred embodiment, the melt-spun drawn or undrawn flame-resistant and anti-fusing continuous 463.53 9

48.1 6 5 n filament of this invention has a tenacity of at least

g/de, for example, 1.0 to 2.5 g/de, and an elongation of at least 20 for exalple 20 to 50

The tenacity and elongation of the filament

and the spinnability of the molten mixture of the novolac

resin and the aliphatic polyamide resin of this invention

were measured by the following methods.

Tenacity and Elongation

JIS L-1074

Spinnability

The molten mixture of the two resins dscribed

above is spun in an amount of 8 g per minute from a

spinneret having 32 holes with a diameter of 0.5 mm,

and wound up at a rate of 1,000 meters per minute. The

number of broken filaments per minute is counted, and

used as a measure of the spinnability. In the present

invention, this number should be less than one per minute.

The invention will be described further by

the following Examples together with Comparative Examples.

Examples 1 to 5 and Comparative Examples 1 to 4

141 g of phenol, 118 g of formalin (37 aqueous

solution), 2 g of oxalic acid, and 30 g of methanol were

heated at 1000 C. with stirring, and reacted for 3 hours.

The reaction was terminated by adding a large quantity

of cold water. The resulting novolac resin was dissolved

in methanol, and the unreacted matter and solvent were

removed by evaporation at reduced pressure. A heat-fusible

novolac resin having a number average molecular weight

of 720 was obtained.

4 3,53 9

48.1 6 5 n2 The novolac resin obtained was pulverized, and mixed well with powdery nylon 6 having an intrinsic viscosity, as measured in meta-cresol at 300C., of 1.2, in an amount of 0, 0.1, 1.0, 3.0, 5.0 and 10.0 by weight, respectively. The mixture was melted by heating to 170°C., and defoamed in a nitrogen atmosphere. The spinning mixture so prepared was again melted at 140°C., and melt spun in an amount of 1 g per minute using a spinneret having I hole wiTh a diameter of 1.5 mm in an atmosphere of nitrogen held at 0.2 kg/cm 2 guage. The filaments obtained were wound up on a wind-up roll with a diameter of 20 cm at a rate such that the filaments could be wound up without breakage for at least minutes. The filaments were immersed under tension for 16 hours in an aqueous solution containing 19 by weight of formaldehyde and 18 by weight of hydrochloric acid at 20°C. The temperature was gradually raised to 100C. in the course of6 hours in a closed vessel, and at this temperature, the filaments were cured for 4 hours, followed by washing with water and drying to form a continuous filament. The results obtained in Examples 1 to 5 and Comparative Examples I to 4 are given in the following Table 1.

463.539

4 8.16 5 n2.

I 0 O 00 CoL -Ii

0 0 c

H0 oI~ 0 0 ttA 0 ON 0 0 0 c'J m~ 4 4. ^y

Cl) r-4

00).. (4 -4'

a 0)40c 4) H4- g0 I2 0 '0 in 4 1- co0 mcs w) co r4 4-. .0

ri 0

4 8 8 8 8 8 8 8 4) Hi4

02 1- n i*N 00 ObD I W~ 4 i 0.

110 H $4 Aw> .00d +3 02 -H4 a'l o Co 0 0 w 8 8. aC) CA HOZC (D(1 H. :2

r-I44 4) 4) 0) W) a) 2 l) 00a) H H rI 4 4$4r-S4H cN

04 04 ON

A "3.5 3 9

49816 5n2 Thus, the mixture of a novolac resin with nylon

6 in an amount of 0.1 5 by weight has better Melt-

spinnability thanthe novolac resin alone. From this mixed

resin, there can be obtained fibers which are infusible

and non-combustible and have tenacity and elongation

same as those of ordinary phenol fibers. On the other

hand, the novolac resin fibers used as control cannot

be taken up at an increased take-up rate because of poor

melt-spinnability, and even in a low speed take-up, it

is difficult to adjust the viscosity of the resin to

one suitable for spinning. Filament breakage tends to

occur, and it is difficult to obtain a continuous yarn.

Filaments of novolac resin containing 10 of nylon 6

in the cured state suffer from adhesion between the

individual fibers in spite of their excellent spinnability.

Also, when these filaments were brought close to flame,

some flame was generated in the filaments. Example 6

A mixture consisting of 141 g of phenol, 54 g

of p-cresol, 130 g of formalin (37 aqueous solution of 0 formaldehyde) and I g of oxalic acid was heated at 100 C.

for 3 hours with stirring, and the reaction product was

neutralized with 0.9 g of sodium hydroxide. The novolac

resin obtained was washed with water, and then further

heated to 160°C. and maintained at this temperature for

3 hours at 5 mmHg to remove the solvent and low boiling

matters. The final novolac resin had a number average

molecular weight of 850 as measured by a vapor pressure

permeation tester. 46 3539

48.165nm

97 g of the novolac resin was thoroughly mixed

with 3 g of powdery nylon 66 having an of 0.87, and

then the mixture was melted was melted uniformly at 230 C. in an

atmosphere of nitrogen, cooled and solidified, and then

pulverized to form a granular product. A test tube was

charged with theresulting resin and heated externally to melt and

defoam the contents completely under the same conditions

as in Example 1. The inside temerature of the test tube was

maintained at 160 0 and the molten mass was allowed to flow out

under a nitrogen gas back pressure of 0.2 kg/cm2 followed by

wind-up on a rotary drum at a speed of 1300 meters/min.

For comparison, the novolac resin alone was

melt-spun under the same conditions as described above. At a

wind up speed of 1300 meters/min., breakage of the filament happen

frequently immediately below the nozzle, and could not be collected

as continuous filament. The continuous wind-up of the filament

was possible at a speed of 750 meters/min.

Each of the two kinds of the filament obtained

was immersed in a mixed aqueous solution consisting of 18%

hydrochloric acid and 18 formaldehyde at 20 C for 10 hours.

The filament which was thus treated was placed on a strainer in

a closed vessel including the strainer at the bottom and a condenser at the head. Then, equal amounts of 35% hydrochloric

acid and 36 formaldehyde were poured into the lower portion of

the strainer, and the space in the vessel was completely replaced

by a nitrogen gas. Then, the lower portion was heated to evaporate

16 463.539

4 8.16 5 n2 a mixed gas of hydrochloric acid and formaldehyde. Under tlhese concitionz, tho t.nperat r--f th s-..nce '.hich

held the filament was gradually raised from 200 C. to 980 C. in the course of 4 hours, and at 980 the filament was allowed to stand for an additional 2 hours. The closed vessel was cooled, and the cured filament was withdrawn. It was washed sufficiently with water to neutralize it further with 2 aqueous ammonia, and further washed with water, followed by drying. Then, the various physical properties of the filament were measured. The nylon 66-incorporated filament obtained by this invention had a filament diameter of 12 microns, a tensile strength of 1.8 g/d and an elongation of 14 When flame was brought close to the filament, it did not at all melt nor give off flame, and was immediately converted to a fibrous carbonized product. On the other hand, filaments obtained from the novolac resin alone had a filament diameter of 28 microns, a tensible strength of 1.3 g/d and an elongation of 22 and the same properties as the filament of the present invention when brought close to flame. As is clearly seen from thiS Example, the melt- spinnability of the novolac resin is markedly improved by incorporation of nylon. This makes it possible to spin fine-denier continuous filaments at high speed, and this contributes the improvement of fiber properties after curing. When the ratio of mixing plon is 3 the heat infusibility and non-combustibility of phenolic resin fibers are not lost at all. 4 6 3. 5 3 9

4 S.16

g of the 7.ovolac resin prepared in Exam;.ple ,12-nylon chips having was uniformly mixed with 5 g of 11 uniformly melted an (rI)of 1.02, and the mixture was followed by in an atmosphere of nitrogen at 2100C, the mixed defoaming, cooling and coasely pulverizing resin was resin. The resulting 11,12-nylon-incorporated a projecting nozzle charged in a test tube equipped with of about 1.5 mm including one hole with an inner diameter in Example 2. The interior which was the same as that used 1500C., and the resin was of the test tube was heated at a nitrogen gas back pressure extruded into a filament under of of 0.3 kg/cm 2 and wound up on a drum at a speed was wound back in 1600 meters/min. The uncured filament the form of skein. solution The skein was immersed in an aqueous the same method and of hydrochloric acid and formalin by Example 1, and cured under the same conditions as used in of the liquid at an elevated temperature. After removal was completely and washing with water, the cured fiber neutralized with a I ammonia aqueous solution, washed dry cured filament thoroughly with water, and dried. The on a cone. was wound back in the form of filament was For comparison, the novolac resin alone The uncured spun at 1400C. at a speed of 500 meters/min. a skein, and it was filament could not be wound back on impossible to form a cured filament.

463.539

4 8.1 6 5 n2 The filamentary cured yarn obtained by the

ab-ov-L.zntione had a filcen-t diaeter of 13 hcthod

microns, a tensile strength of 1.9 g/d, and an elongation

of 38 and retained the same good infusibility and

non-combustibility as the yarns obtained in Examples 1 and 2. Example 8

The novolac resin fibers containing 3 of 66-

nylon which were obtained in Example 2 were immersed

for 16 hours at 20oC. in a mixed aqueous solution

containing 18 hydrochloric acid and 19 paraformaldehyde,

and cured under the same conditions and by the same method

as those used in Example 2. After washing with water and

drying, the cured fibers had a tenacity of 1.6 g/d and

an elongation of 35 and had excellent infusibility and

non-combustibility.

463,5 3 9

Claims (4)

4 8,1 6 5 n THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A melt-spun drawn or undrawn flame-resistant

and anti-fusing cured phenolic continuous filament which

has been cured in the presence of an acid catalyst, which filament

comprises a novolac resin and an aliphatic polyamide resin

in an amount of less than 5% by weight but not less than 0.1

by weight based on the total weight of said two resins.

2. The filament according to claim 1, characterized

in that said aliphatic polyamide resin is selected from the group

consisting of nylon 6, nylon 11, nylon 12, nylon 66, nylon

610, nylon 611, nylon 612 and a bend thereof.

3. A filamentary structure in a form selected from

the group cinsisting of fibers, yarns, knitted fabrics,

woven fabrics, non-woven fabrics and felt, which contains a

filamentary material derived from a melt-spun drawn or undrawn

flame-resistant and anti-fusing cured phenolic continuous fila-

ment which has been cured in the presence of an acid catalyst, which

filament comprises a novolac resin and an aliphatic polyamide

resin in an amount of less than 5 by weight but not less than

0.1 by weight based on the total weight of said two resins.

4. A process for producing a flame-resistant and

anti-fusing cured phenolic continuous filament, characterized

by melt-spinning a molten mixture of an uncured novolac resin and an aliphatic polyamide resin in an amount of less than

by weight but not less than 0.1 by weight based on the

total weight of said two resins.

463.5 3 9

48,1 6 5 /72 and then curing the melt-spun filament wvith a curing agent

in th? presence of an acid catalyst.

The process according to claim 4, characterized in that said aliphatic polyamide resin is selected from

the group consisting of nylon 6, nylon 11, nylon 12,

nylon 66, nylon 610, nylon 611, nylon 612 and a blend

thereof.

6. The process according to claim 4, characterized

in that said curing agent is selected from the group

consisting of formaldehyde and paraformaldehyde.

7. The process according toclaim 4, characterized

in that said acid catalyst is selected from the group

consisting of mineral acids, carboxylic acids and mixtures

thereof.

8. Theprocess according to claim 4, characterized

in that said 4 curing is effected at a temperature of

from 5° toP9/1502

9. The process according to claim 4, characterized

in that the melt-spun filament is drawn before or after

curing, or both before and after curing.

The process according to claim 9,characterized

in that the draw ratio is up to 2.5 based on the length

of the undrawn filament.

DAT3D: 25th October, 1972

PHILLIPS ORO.ONDE FITZPATRICK Attorneys for NIPPON KYTOL INCORPORATED

*G C

4 3.5 3 9