JP3099984B2 - Method for producing polyphenylene sulfide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyphenylene sulfide having a small stain on a die at the time of extrusion. More specifically, the present invention relates to a method for producing a polyphenylene sulfide at a relatively high temperature in an oxygen-free inert atmosphere. The present invention relates to a method for producing polyphenylene sulfide having a reduced low molecular weight.

[0002]

2. Description of the Related Art Polyphenylene sulfide (hereinafter PPS)
In particular, poly-p-phenylene sulfide is excellent in mechanical properties, thermal properties, electrical properties, etc., due to dielectric properties of capacitors, electrical insulating materials, electronic components,
It is used for acoustic diaphragms and release materials.

[0003] However, when PPS is produced by a method which is usually carried out on an industrial scale, mixing of a low molecular weight material is unavoidable, and the low molecular weight material adheres to a die portion at the time of extrusion molding. When producing a stretched film, there is a problem that the film-forming property is remarkably reduced. That is, the low molecular weight material attached to the base portion adheres to the extruded sheet,
In order to cause breakage during biaxial stretching and to remove deposits, it was necessary to frequently stop the film forming machine and clean the base.

As a method for removing such low molecular weight substances in PPS, a method of washing a polymer with an organic solvent (Japanese Patent Application Laid-Open No. 59-6221 and Japanese Patent Application No. 63-72980) is known. A method for removing the used solvent (Japanese Patent Application Laid-Open No. 59-89327) has been proposed, but is still insufficient.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional PPS, to reduce the amount of low-molecular-weight substances adhered to the die during extrusion and to obtain a good film-forming property with less die stain. Another object of the present invention is to provide a simple PPS manufacturing method.

[0006]

According to the present invention, in order to achieve the above object, the melt index at a temperature of 315.6 ° C. is not less than 0.5 g / 10 min and not more than 200 g / 10 min .
Polyphenylene sulfide having a degree of crystallinity of 30% or more under an inert atmosphere having an oxygen partial pressure of 20 mmHg or less.
200 ° C or more 5 ° C from the melting point of polyphenylene sulfide
Melt index before and after treatment in a temperature range up to low temperature
A method for producing polyphenylene sulfide, which is characterized by performing a heat treatment so that the difference in the satisfies the expression (1) . −5.8 ≦ 100 × (η−η ₀ ) / η ₀ ≦ 30 (1) where, η: Melt index after heat treatment η ₀ : Melt index before heat treatment .

The polyphenylene sulfide referred to in the present invention mainly includes poly-p-phenylene sulfide, and preferably contains at least 70 mol% of p-phenylene sulfide units. More preferably, 90 mol% or more is a p-phenylene sulfide unit.
If such a unit is less than 30 mol%, for example,

[0008]

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It is possible to contain such as a copolymer component, but it is more preferable that the content of these copolymer components is 10 mol% or less. In particular,

[0010]

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The content of the polyfunctional copolymer component having three or more functional units is preferably 2 mol% or less.

The starting material PPS used in the present invention is
It can be obtained by a conventionally known method, that is, by reacting an alkali sulfide with p-dihalobenzene in a polar solvent under high temperature and high pressure. In particular, sodium sulfide and p-
It is preferable to react dichlorobenzene in an amide-based high-boiling solvent such as N-methylpyrrolidone. In this case, in order to adjust the degree of polymerization, a so-called polymerization aid such as caustic alkali and an alkali metal carboxylate is added, and the
Most preferably, the reaction is carried out at a temperature of from 280C to 280C. The pressure and the polymerization time in the polymerization system are appropriately determined depending on the type and amount of the auxiliary agent used, the desired degree of polymerization, and the like.

[0013] In order to maintain the electrical insulation performance of the finally obtained film, a polymerized polymer (generally in powder form) is required.
Is preferably washed with water or an organic solvent not containing metal ions to remove by-product salts, polymerization aids, and the like during polymerization, and to reduce the ionic carrier concentration sufficiently. In this case, the total inorganic content in the polymer is 5000 ppm or less, and calcium 1
000 ppm or less and sodium 500 ppm or less are preferred.

When the polymer is in the form of powder, it can be extruded in a gut shape using a twin screw extruder in advance and pelletized. At this time, an antioxidant, a heat stabilizer, a lubricant, a nucleating agent, an ultraviolet absorber, a coloring agent, and the like can be added.

The temperature of PPS used for the heat treatment is 315.6.
The melt index at 0 ° C is 0.5 g / 10 min or more,
It is necessary to be 200 g / 10 minutes or less. Preferably it is 5 g / 10 min or more and 150 g / 10 min or less, more preferably 10 g / 10 min or more and 120 g / 10 min or less. If the melt index is less than 0.5 g / 10 minutes, extrusion becomes difficult, which is not preferable. On the other hand, 20
If it exceeds 0 g / 10 minutes, it is not preferable because the uniformity of the thickness when extruded into a film or the like is poor.

In the present invention, the heat treatment temperature is not lower than 200 ° C. and not higher than the melting point of PPS by 5 ° C. Preferably 220 ° C. or higher, up to 5 ° C. lower than the melting point of PPS,
More preferably, the temperature is 230 ° C. or higher and 5 points higher than the melting point of PPS.
Up to ℃ lower temperature. If the heat treatment temperature is lower than 200 ° C., it is difficult to reduce low molecular weight substances causing stains on the die, which is not preferable. On the other hand, if it exceeds the melting point, it will be melted and adhere to the equipment, thermal degradation will increase , and if it is in the molten state, the effect of reducing low molecular weight substances will be reduced.
It is necessary to perform in the solid state because the fruits are small
In the present invention, the temperature is specified to be 5 ° C. lower than the melting point.
are doing. .

In the present invention, the atmosphere in which the heat treatment is performed must be an inert atmosphere having an oxygen partial pressure of 20 mmHg or less. Preferably, the oxygen partial pressure is 10 mmHg or less,
More preferably, it is 5 mmHg or less. Oxygen partial pressure 2
When heat treatment is performed in an atmosphere exceeding 0 mmHg, PP
This is not preferable because oxidative crosslinking of S occurs and the molded article becomes brittle. The inert atmosphere is used to replace air with a gas that is chemically inert with PPS and at the same time remove low molecular weight substances from the system. Preferably, a nitrogen stream is used.
Of course, the total pressure may be any pressure as long as the oxygen partial pressure is 20 mmHg or less.

[0018] In the present invention, further the difference between the melt index eta after heat treatment and the melt index eta ₀ before heat treatment of PPS (η-η ₀₎ is, -5.8 ≦ 100 × (η- η 0) / η ₀ ≦ 30 (1) will rows the heat treatment to be in the range of. This equation (1)
The value “−5.8” is the value obtained from Example 4 described later.
is there. The melt index of PPS varies depending on the degree of polymerization of polymer, terminal groups, and degree of branching, and these vary depending on operating conditions such as the type of apparatus used for heat treatment, treatment temperature, time, and atmosphere. However, within the range of the oxygen partial pressure specified in the present invention, the change in the melt index of the polymer can be reduced even when the heat treatment is performed. The heating temperature and pressure are set within the above-mentioned ranges, and the heating time is usually preferably 30 minutes or more and 10 hours or less.

As the heat treatment apparatus used in the present invention, P
What can heat PS uniformly is preferable. In particular,
A rotary dryer, a fluidized bed dryer, a dryer having various stirring blades, and the like can be used.

The PPS in the heat treatment may be in the form of powder or pellets, but is preferably in the form of guts for ease of handling. Moreover, the film waste once formed into a film may be shredded.

Further, in the present invention, P
It is preferable that PS is crystallized in order to avoid fusion during heat treatment.
The crystallinity of PPS subjected to heat treatment to 30% or more.
are doing. It is preferably at least 35%.

As described in detail above, according to the present invention, it is possible to obtain PPS in which low-molecular-weight substances causing stains on the base are reduced without significantly changing the melt index.

[0023]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. The evaluation was performed by the following method.

(1) Strength and elongation The tensile strength and elongation at break of a sample having a width of 10 mm and a test length of 50 mm were determined using a Tensilon type tensile tester, and n = 5.
Was calculated as the average value.

(2) Melt index According to ASTM D-1238-70, load 5 kg, 3
Value measured at 15.6 ° C. and expressed in g / 10 minutes.

(3) Melting point Measured using a differential scanning calorimeter (DSC-2).

(4) Crystallinity The density of the polymer was determined by a density gradient tube using an aqueous solution of lithium bromide, and the crystallinity (Xc) was determined by the density method using the density. That is, the density is obtained by the following equation that is generally used. (100 / d) = (Xc / dcr) + [(100−Xc) / dam｝ (2) In the formula (2), d, dcr and dam are the density of the sample, the density of the crystalline phase, and the density of the amorphous phase, respectively. It is. Here, dcr and dam are Eur. Poly. J. , 7,
1127 (1971). That is, dcr = 1.43 g / cm ³ and dam = 1.3.
2 g / cm ³ .

(5) Dirt on the die The determination was made according to the following criteria from the adhesion amount of the low molecular weight substance near the die during film formation and the state of occurrence of film breakage caused by the amount. ：: Even after the film was formed for 10 hours, there was almost no adhesion to the die and no film tearing occurred. Δ: After film formation for 10 hours, there was a deposit on the die, and during that time, the film was occasionally torn. X: A large amount of deposits were found on the die after several hours of film formation, the film was frequently torn, and the die was cleaned to continue film formation.

Example 1 (1) Preparation of PPS Into an autoclave, 100 mol of sodium sulfide nonahydrate, 45 mol of sodium acetate and 25 l of N-
Methylpyrrolidone (hereinafter abbreviated as NMP) was charged, the temperature was gradually raised to 205 ° C. while stirring, and the contained water was removed by distillation.

Into the dehydrated system, 101 mol of p-dichlorobenzene and 8 L of NMP were added, and 170 ml of NMP was added.
After pressurizing and filling nitrogen at 3 kg / cm ² at 25 ° C.,
Polymerization was performed at 0 ° C. for 4 hours. After the completion of the polymerization, the mixture was cooled, the polymer was precipitated in distilled water, and a small block polymer was collected by a wire mesh having a 150 mesh opening.

The polymer was washed five times with distilled water at 90 ° C., and then dried at 120 ° C. under reduced pressure to have a melting point of 283
C. White granular PPS was obtained.

(2) Pelletizing PPS Next, calcium carbonate having an average particle size of 1.2 μm was mixed with the obtained granular PPS so as to be 0.7% by weight based on the PPS, and the mixture was heated to 320 ° C. with a twin-screw kneader. The mixture was melt-kneaded, discharged from a strand, and cut to form a PPS pellet having a diameter of 2 to 3 mm and a length of 3 to 4 mm.

(3) Heat treatment of PPS The PPS pellets obtained in the above (2) were heated at 180 ° C.
It was dried under reduced pressure of 0 mmHg or less for 2 hours to be pre-crystallized. The crystallinity of the obtained PPS pellet was 40%. Next, the pellets were charged into a rotary dryer, and the atmosphere was repeatedly replaced with nitrogen under reduced pressure and filled with nitrogen.
Heat treatment was performed at 0 ° C. and an oxygen partial pressure of 1 mmHg (total pressure of 5 mmHg) for 4 hours. The melt index of the PPS pellet after the heat treatment was 70 g / 10 minutes.

(4) Film formation The PPS pellets obtained in the above (3) are supplied to an extruder, subsequently discharged from a T-die type die provided, rapidly cooled by a cooling rotary drum, and have a substantially amorphous thickness. 55 μm
Was obtained.

Next, the sheet is caused to travel in contact with a plurality of heating rolls having a surface temperature of 95 ° C., and 3.7 mm in the longitudinal direction between the sheet and a cooling roll of 30 ° C. provided with a different peripheral speed next to the heating roll group. It was stretched twice. This uniaxially stretched sheet is stretched 3.7 times in a direction perpendicular to the longitudinal direction at 100 ° C. using a tenter,
Subsequently, heat treatment was performed at 260 ° C. for 10 seconds to obtain a biaxially stretched PPS film having a thickness of 4 μm. In this film formation, the film was not torn once in 10 hours, and there was almost no deposit on the base after 10 hours, and the stain was extremely small. In addition, the mechanical properties of the obtained film were good.

The heat treatment conditions, the results of film formation and the properties of the obtained films are listed in Table 1.

Examples 2 to 6 and Comparative Examples 1 to 3 PPS production, heat treatment and film formation were carried out in the same manner as in Example 1 except that the heat treatment conditions were changed as shown in Table 1. A PPS film was obtained. The results of film formation and the properties of the obtained biaxially stretched PPS film are shown in Table 1. According to the method of the present invention, stains on the die during film formation are reduced, and the mechanical properties of the obtained film are further reduced. It can be seen that the characteristics are also good.

COMPARATIVE EXAMPLE 4 The operation of stirring the white granular PPS obtained in Example 1 (1) at 70 ° C. for 30 minutes by using a 5-fold amount of NMP by weight and then filtering it was repeated three times. And dried at 150 ° C. using a vacuum drier. The melting point of the obtained polymer was 284 ° C.

Then, calcium carbonate having an average particle diameter of 1.2 μm was mixed with the obtained granular PPS so as to be 0.7% by weight based on the PPS, and the mixture was melt-kneaded at 320 ° C. with a twin-screw kneader to obtain a strand. More discharge, cut 2-3mm diameter,
PPS pellets having a length of 3 to 4 mm were obtained.

The obtained PPS pellet was heated at 180 ° C. for 1 hour.
It dried under reduced pressure of 0 mmHg or less for 2 hours. P obtained
The crystallinity of the PS pellet was 40%.

Next, the obtained PPS pellets are supplied to an extruder, subsequently discharged from a T-die die provided and rapidly cooled by a cooling rotary drum to obtain a substantially amorphous thickness 5 mm.
A 5 μm PPS sheet was obtained.

Next, the sheet is run in contact with a plurality of heating rolls having a surface temperature of 95 ° C., and 3.7 mm in the longitudinal direction between the sheet and a cooling roll of 30 ° C. provided at a different peripheral speed next to the heating roll group. It was stretched twice. This uniaxially stretched sheet is stretched 3.7 times in a direction perpendicular to the longitudinal direction at 100 ° C. using a tenter,
Subsequently, heat treatment was performed at 260 ° C. for 10 seconds to obtain a biaxially stretched PPS film having a thickness of 4 μm.

When the film was formed for 6 hours, the film was frequently broken. Therefore, the base was cleaned. However, the film was broken four times thereafter.

Table 1 shows the heat treatment conditions, the results of film formation, and the characteristics of the obtained films.

Examples 7 and 8 and Comparative Example 5 Polymerization was carried out in the same manner as in Example 1 (1) except that the polymerization time was changed to obtain granular PPS having different melt indexes. Using the obtained PPS, (2) to (2) of Example 1
A biaxially stretched PPS film was produced in the same manner as in (4). The results are shown in Table 1. According to the method of the present invention,
It can be seen that the base is hardly stained and the film is not broken.

Example 9 Production of PPS, pelletizing, heat treatment, and heat treatment were carried out in the same manner as in Example 1 except that heat treatment was carried out in a nitrogen stream at a flow rate of 2 m 3 / hour (oxygen partial pressure 1 mmHg or less) instead of heat treatment under reduced pressure. The membrane was performed. The film did not tear, and the base was not dirty.

[0047]

[Table 1]

[0048]

According to the PPS obtained by the present invention, since low-molecular-weight substances causing stains on the base are reduced, the breakage at the time of film formation is reduced, so that the base can be cleaned less frequently. It has the feature that the film formability is significantly improved.

The PP obtained by the method of the present invention as described above
S can be used particularly effectively when melt-extruded to form an unstretched sheet or a uniaxially or biaxially stretched film. In addition, since the low molecular weight material is small, the obtained film not only has excellent electrical and mechanical properties, but also has excellent uniformity of these properties, such as electric insulating materials such as motors and transformers, and dielectrics for capacitors. , Various release materials and circuit boards. Furthermore, it can be effectively applied to the field of fibers and other molding materials.

Claims (1)

(57) [Claims] The melt index at a temperature of 315.6 ° C. is 0.5 g / 10 min or more and 200 g / 10 min or less, and
Polyphenylene sulfide having a crystallinity of 30% or more is placed in an inert atmosphere having an oxygen partial pressure of 20 mmHg or less under an inert atmosphere.
00 ° C or higher, 5 ° C lower than the melting point of polyphenylene sulfide
Melt index before and after treatment in the temperature range up to
A method for producing polyphenylene sulfide, wherein the heat treatment is performed so that the difference in satisfies the expression (1) . −5.8 ≦ 100 × (η−η ₀ ) / η ₀ ≦ 30 (1) η: Melt index after heat treatment η ₀ : Melt index before heat treatment