JPS5842283B2 - Melt spinning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention reduces the occurrence of nozzle fouling during melt spinning of thermoplastic polymers, and more specifically, prevents the occurrence of nozzle fouling by improving the heat resistance of the silicone oil composition applied to the nozzle surface. The present invention relates to a melt spinning method that can extend the spinneret correction interval.

Generally, in melt spinning of thermoplastic polymers, low-molecular substances contained in the polymer and substances generated by thermal decomposition of the polymer are liberated from the spun yarn and adhere to the vicinity of the nozzle discharge hole, causing deterioration and staining of the nozzle. .

As this nozzle dirt increases, the spun yarn may twitch,
The yarn may bend or break, causing spinning problems.

Therefore, before these troubles occur, it is necessary to clean the cap surface, and this cleaning operation is called cap repair.

Further, the interval from one modification to the next modification is called a modification interval.

Since spinneret correction interrupts spinning, there are significant downsides such as lower yield and quality. Extending the correction interval and reducing the number of corrections improves yield, improves quality, and reduces the number of workers required for correction. The effects are significant, including a reduction in

In general, when melt spinning thermoplastic polymers, it is recommended to apply silicone oil on the spinneret surface, which has better heat resistance and mold release properties than general organic oils.
As shown in 7773, it has become common knowledge in this industry.

The purpose of applying this silicone oil is to prevent the polymer from adhering to the nozzle surface when starting spinning, and also to prevent dirt from forming around the nozzle hole during spinning, and to easily remove any dirt that has occurred. This is to do so.

However, even though silicone oil has good heat resistance, when melt spinning polyester or polyamide, the temperature of the spinneret surface is usually maintained at a high temperature of about 2708C to 300C, so the applied silicone oil is exposed to air. It undergoes oxidative decomposition by oxygen and rapidly denatures, eventually becoming a gel without losing its fluidity.

While silicone oil maintains its fluidity, it maintains its releasability and there is little dirt accumulation around the nozzle hole, but as the silicone deteriorates and gels, dirt accumulates rapidly and Spinning troubles occur when the yarn twitches or bends.

Therefore, in order to extend the interval between fittings, it is sufficient to improve the heat resistance of silicone oil, but regarding the heat resistance of silicone oil, dimethyl silicone oil starts to decompose due to oxidation at around 200°C. It is well known that there are problems with long-term use in air at temperatures higher than this.

In addition, methylphenyl silicone oil, which has a structure in which some of the methyl groups of this dimethyl silicone oil are replaced with phenyl groups, has improved heat resistance than dimethyl silicone oil, but for example, when the phenyl group: methyl group is 1 = 3, It is also a well-known fact that some methylphenyl silicone oils begin to undergo oxidative decomposition at about 270° C. and cannot be used for long periods in air at higher temperatures.

Further, although chlorophenyl silicone oil has slightly better heat resistance than dimethyl silicone oil, it cannot withstand long-term use at temperatures above 250°C.

By the way, when evaluating heat resistance, it is necessary to regulate the temperature, time, surrounding medium (in air, nitrogen, etc.), contact area with the medium, etc.

In general, factors other than input temperature and time are held constant, and the maximum value is processed for a period of time during which no change in the property of interest of the measured substance occurs or the property remains within a predetermined tolerance limit. A method is used in which the heat resistance of the substance to be measured is evaluated by determining it as a function of temperature.

Furthermore, for convenience, it may be acceptable in some cases to determine the maximum time for a given temperature of interest and use this as a relative evaluation measure of heat resistance.

In the heat resistance evaluation in the present invention, unless otherwise specified,
The contact area with air in circulating heated air at 290℃ is 2.2
7 crti/? In this case, the maximum time during which the fluidity of the substance to be measured is maintained is adopted, and is hereinafter referred to as the gelation time.

For example, dimethyl silicone oil with a viscosity of 1000C8 (at 20°C) gels in about 6 hours in air at 290°C without losing fluidity, and methylphenyl silicone oil with a viscosity of 300C8 (at 20°C) (phenyl group: Methyl group =
1:3) gels after about 100 hours in air at 290°C.

After all, silicone oil alone cannot provide a product that can withstand long-term use in such high-temperature air of 270° C. or higher.

In this type of oxidative decomposition of silicone oil, the hydrocarbon groups bonded to the silicon atoms in the organopolysiloxane main chain of its constituent polymer are attacked by oxygen, and the generated radicals in the main chain are bonded as appropriate. , it is thought that gelation occurs by creating intermolecular crosslinks.

Therefore, if this oxidative decomposition can be prevented or suppressed by some means, silicone oil can be used in high-temperature air, and various antioxidants have been proposed for this purpose.

For example, amines, organic selenium compounds, phenols,
Alternatively, it is a well-known fact that heat resistance is significantly improved by adding a small amount of iron compounds such as ferrocene and iron octoate to silicone oil.

In fact, when iron octoate was added to the dimethyl silicone oil (100OCs) at the same temperature of 290℃
It maintains fluidity in air for about 600 hours, and the heat resistance time is improved by about 100 times.

As described above, antioxidants are extremely effective in improving the heat resistance of silicone oil, but it is difficult to use silicone oil to which such antioxidants have been added to melt spinnerets such as polyethylene terephthalate, which has terephthalic acid as one of its main components. It has been found that there are significant drawbacks when applied.

In other words, terephthalic acid generated from the molten polymer causes the antioxidant to lose its effectiveness, causing deterioration of the silicone oil and
It was found that gelation occurred in a short period of time, causing spinning troubles as described above.

The present inventors have solved these problems and created silicone oil free
The present invention was arrived at as a result of intensive research into improving heat resistance.

That is, the present invention has a viscosity of 50 to 10 at 25°C.
000 centistokes and containing phenyl groups and methyl groups in a ratio of 1 = 20 to 1 = 1. ■ 5 weight of wet process fine powder silica having a pH of 8 or less in an aqueous solution from 0.1 to 1. This is a melt spinning method characterized by applying a silicone oil composition with good heat resistance, which has been added and mixed in an amount of 30% by weight, to the surface of a melt spinneret of a thermoplastic polymer and spinning.

In the present invention, the silicone oil is substantially It is an organopolysiloxane represented by the structural formula.

R in this structural formula is an alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, cycloalkenyl group, a substituted derivative thereof, a hydroxyl group, or a hydrogen atom.

Examples include methyl, ethyl, phenyl, benzyl, vinyl, cyclohexyl, trifluoropropyl, cyclohexenyl, chlorophenyl, and hydroxyethyl groups, but these are merely examples and are not limited thereto.

All R's in this structural formula may be of the same type, or a structure in which several different groups are mixed and combined may be arbitrarily adopted.

It is essential that the phenyl group:methyl group of R in these organopolysiloxanes be methylphenyl silicone in a ratio of 1:20 to 1=1 in order to extend the base correction cycle.

These organopolysiloxanes are essentially linear polysiloxanes.

However, those containing a small amount of groups other than the diorganosiloxane group of the main chain forming unit are also considered.

Therefore, for example, it may contain a small amount of trifunctional silicon atoms, or may also contain a small amount of sylmethylene group or 5i-8i bond.

These groups are inevitably produced during the production of organopolysiloxane.

Of course, the R group itself, a physical mixture of two or more organopolysiloxanes having different composition ratios, a block copolymer, and a graft copolymer may also be considered.

The molecular weight of these silicone oils may be selected as appropriate depending on the polymerization method or application, but a minimum molecular weight that does not boil at the operating temperature and other environmental conditions should be ensured, and appropriate fluidity should be maintained at the beginning of use. The upper limit of the molecular weight is naturally determined in order to guarantee the molecular weight.

In practice, the relationship between molecular weight and viscosity differs depending on the type of OR in the structural formula, and in order to realize the effects of the present invention, a silicone oil with a viscosity of 50 to 10,000 centistokes at 25°C is used. is effective.

The silicone oil itself related to the present invention is already well known, for example, as described in ``Chemistry and Toxicity of Silicone Oil''(' Chemistry
y and Technology of 5ilico
nes “Waiter No1l, 5eond
Edition (1968) Academic Pr
ess) New York and London
) and are systematically summarized in books such as

Also, these silicone oils are called Talk Silicone K.
K.

These are widely manufactured and commercially available by Toshiba Silicone KK, Shin-Etsu Chemical KK, and others.

In the present invention, wet-process silica is treated by decomposition treatment using an acid, ammonium salt, ion exchange resin, etc. of sodium silicate, decomposition with an acid of an alkaline earth salt derived from sodium silicate, or decomposition of an alkali silicate with carbon monoxide. It is a so-called wet process silica obtained by methods such as silica.
It is several hundred millimeters in size.

The acidity of the wet process silica produced by the above method differs depending on the manufacturing conditions, and the effects of the present invention can be realized when the pH value of the 5 weight polyaqueous solution is 8 or less, preferably 7 or less.

Commercial wet process silica products that meet these requirements include:
These include Carplex (Shionogi & Co., Ltd.), Nip Sil (Nihon Shirikanigyo), Tokusil (Tokuyama Soda), VitaSeal (Takihihi), and Himezil (Ehime Pharmaceutical).

These commercially available wet process silicas contain impurities such as CaO, Mg0tA1203 pNa20, etc. in addition to the main component 5i02, but their presence is allowed as long as the above pH value is satisfied.

Furthermore, the presence of many to several tens of tons of water contained in this wet process silica is harmless to obtaining the effects of the present invention.
In fact, if this moisture is removed by intense heat, the effects of the present invention may not be fully achieved, so care must be taken.

By the way, there is another typical manufacturing method for fine powder silica.
There is so-called dry process silica which is synthesized by hydrolysis of organosilicon compounds or silicon tetrachloride in an oxyhydrogen flame, and is commercially available under the trademark Aerosil (Japan Aerosil), which is suitable for use in the present invention. It does not show any effect of improving the heat resistance of silicone oil.

It is unknown why only wet process silica works effectively in the present invention, but it is a truly surprising new fact, and until now, the existence of such a phenomenon was completely unknown. It is something that

However, a combination of wet process silica and dry process silica may be considered, and may be formulated as appropriate depending on other required properties of the silicone composition.

Even in that case, it is important to make sure that wet process silica coexists.

Incidentally, the manufacturing method of these finely divided silica powders is, of course, well known and has been widely described.

All known cross-talk techniques can be applied to the mixing method of silicone oil and wet silica.

In particular, it is effective to improve the dispersibility of wet silica using a roll.

Wet process silica may be arbitrarily selected depending on the amount of silica added and the degree of heat input resistance required.

The upper limit of addition rate of fine powdered silica is regulated depending on its oil absorption ability, and in order to maintain fluidity in a substantially oily state,
It needs to be 300 parts by weight or less.

The lower limit is 0.1 parts by weight, and below this, no significant effect of improving heat resistance can be expected.

The silicone oil composition used in the present invention can effectively exhibit its heat-resistant effect at high temperatures of 270° C. or higher in the presence of oxygen.

In particular, while conventional silicone oil with the addition of antioxidants loses its heat resistance completely due to the presence of organic chemicals such as carboxylic acids, the silicone oil used in the present invention loses its heat resistance improvement effect. It is noteworthy that it does not jump.

Such a remarkable heat resistance improvement effect of the present invention is observed in a silicone oil composition in which a specific wet-process silica coexists, and an excellent heat-resistant effect that cannot be obtained with a two-component system of dry-process silica and silicone oil can be obtained. This is truly a surprising new fact.

As the thermoplastic polymer effective in the melt spinning method of the present invention, polyester, polyamide, etc. are preferred, and polyethylene terephthalate is particularly preferred.

In melt spinning of polyester or polyamide, when a silicone oil composition prepared by adding and mixing wet silica to the silicone oil described above is applied to a die at 270°C or higher, organic chemicals generated from the Tofu Polymer, such as terephthalic acid,
It has extremely desirable properties, as it is not affected by adipic acid, ethylene glycol, ε-caglolactam, hexamethylene cyanide, etc. and exhibits its heat resistance improving effect, and it not only improves the stability of spinning, but also the subsequent
For example, it is surprising that it also has a favorable effect on stretchability, and is a completely new fact that was previously unknown.

When using the silicone oil composition of the present invention,
This may be used as it is, or it may be considered to further add a solvent, a coloring agent, or other known additives that do not reduce the heat resistance improvement effect of the present invention.

For example, use in an aerosol state by adding chlorocene and dichlorodifluoromethane is also employed in some cases.

The present invention will be further described below with reference to Examples, but these are merely illustrative and the present invention is of course not limited thereto.

Example 1 Methylphenyl silicone with a molar ratio of phenyl groups to methyl groups of 1:3 was added to 90 parts by weight of organopolysiloxane oil with a viscosity of 300 centistokes at 25° C. as wet process silica, pH 6.8 manufactured by Shionogi & Co., Ltd. Car Pre-Las #8
A silicone oil composition was prepared by adding and mixing 10 parts by weight of 0.

According to the heat resistance evaluation method defined in the text, gelation time in circulating heated air at 290° C. was measured and found to be 580 hours.

29 with 48 holes with a diameter of 0.25 mm.
Polyethylene terephthalate with an intrinsic viscosity of 0.66 was applied to the surface of the spinneret at 5°C in contact with the outside air at a drawing speed of 1.
The yarn was spun at 300 m/min and drawn 3.5 times to obtain a drawn yarn of 75 denier and 48 filaments.

Spinning was continued for 15 days without any problems, and the silicone used did not gel.

In addition, when gelation time was measured when terephthalic acid was added to this composition in the case of O9191 part by weight or 1 part by weight, it was 650 hours and 870 hours, respectively, and the heat resistance of the silicone oil composition was as follows. This is equivalent to or longer than 580 hours in the case of additives, and even in the presence of organic chemicals, it still shows the effect of improving heat resistance.In contrast, when only the base methylphenyl silicone oil was applied, Gelation of this silicone oil was observed, and when the polymer separated from the spinneret hole in the form of filaments, twisting occurred frequently, making it impossible to continue normal spinning. It was necessary to carry out cleaning and removal.

Example 2 From a spinneret with 48 holes with a diameter of 0.25 mm.

Polyethylene terephthalate having an intrinsic viscosity of 0.66 was melt-spun at 295°C and taken off at 1300 meters per minute to obtain an undrawn yarn.

This was further drawn 3.5 times at a rate of 600 meters per minute using a rotating roller system with different circumferential speeds to obtain a drawn yarn of 100 denier.

In this case, when the silicone oil composition of the present invention according to Example 1 was applied to the surface of the spinneret (1), the same methylphenyl silicone oil was used as the base silicone oil, and the dry method silica was used as Aerosil 200 (Japanese). When applying a mixture of 10% by weight of Aerosil ■) (
II), and when only the base silicone oil was applied (6), the stretchability was examined and the result was as shown in Figure 1.

Here, as a measure of drawability, when the above-mentioned undrawn yarn is loaded into a drawing machine and a drawn yarn of IKg winding is obtained, troubles such as yarn breakage do not occur, and the number of completely drawn yarns obtained is compared to the number of pieces in progress. It means a ratio, and for convenience, it will be referred to as a stretching excellence ratio.

FIG. 1 shows a graph in which a new spinneret is coated with the silicone oil or its composition, undrawn yarns are pooled every 24 hours after spinning is started, and the change in the drawing excellence rate is observed.

According to this, when dry process silica is added and mixed (II
) Or, in the case of using only silicone oil (E), the stretching excellence rate rapidly decreases from the 3rd day, whereas in the case of using the silicone oil composition of the present invention (I), it is still high even after 14 days. It is known that the excellent effect of improving heat resistance is being taken advantage of.

In cases (9) and (e), the test was discontinued on the 5th and 4th day when the stretchability became 60% or less, respectively.

[Brief explanation of the drawing]

FIG. 1 is a graph comparing the effects of the silicone oil composition of the present invention and other silicone oil compositions on stretching properties.

Claims (1)

[Claims] 1 ■ The viscosity at 25°C is 50 to 10,000 centistokes, and the ratio of phenyl group and methyl group is 1:20.
Add wet process fine powder silica having a pH of 8 or less in a 5 weight polyaqueous solution to silicone oil in a ratio of 1=1.
A melt spinning method characterized by applying a silicone oil composition with good heat resistance, which is added and mixed in an amount of i to 30% by weight, to the surface of a melt spinneret of a thermoplastic polymer and spinning.