JPH05125186A - Method for producing polyphenylene sulfide - Google Patents

Abstract

PURPOSE:To produce a polyphenylene sulfide containing a small amount of low-molecular weight substances to cause cap stain, little in cap stain and excellent-in-film-forming properties in extrusion. CONSTITUTION:A polyphenylene sulfide having <=0.5g/10 minutes to <=200-g/10 minutes, preferably <=10g/10 minutes to <=120g/10 minutes at 315.6 deg.C is heat- treated at >=200 deg.C to <=the melting point of PPS, preferably <=230 deg.C to <=temperature 5 deg.C lower than the melting point of PPS in an inert atmosphere under <=20mmHg oxygen partial pressure.

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 with less contamination of a die at the time of extrusion, and more specifically, it is heated at a relatively high temperature in an oxygen-free inert atmosphere to cause contamination of the die. And a method for producing polyphenylene sulfide having a reduced low molecular weight substance.

[0002]

2. Description of the Related Art Polyphenylene sulfide (hereinafter PPS)
, Especially poly-p-phenylene sulfide, due to its excellent mechanical properties, thermal properties, electrical properties, etc., dielectrics of capacitors, electrically insulating materials, electronic parts,
It is used for acoustic diaphragms and mold release materials.

However, when PPS is produced by a method which is usually carried out industrially, it is unavoidable that a low molecular weight substance is mixed in, and the low molecular weight substance adheres to the die portion during extrusion molding, for example, biaxial. In the case of producing a stretched film, there is a problem that film formability is significantly reduced. That is, the low molecular weight substance attached to the die part 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 die part.

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, Japanese Patent Application No. 63-72980) is used. A method for removing the used solvent (Japanese Patent Laid-Open No. 59-89327) has been proposed, but it has not been sufficient yet.

[0005]

The 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 adhering to the die portion during extrusion, and to reduce the stain on the die and to improve the film formability. Another object of the present invention is to provide a PPS manufacturing method.

[0006]

In order to achieve the above object, the present invention provides a polyphenylene sulfide having a melt index of 0.5 g / 10 min or more and 200 g / 10 min or less at a temperature of 315.6 ° C. Oxygen partial pressure is 20 mmH
A method for producing polyphenylene sulfide, which comprises performing a heat treatment in a temperature range of 200 ° C. or higher and a melting point or lower in an inert atmosphere of g or less.

The polyphenylene sulfide referred to in the present invention is intended mainly for poly-p-phenylene sulfide, and it is preferable that the p-phenylene sulfide unit is present at 70 mol% or more. More preferably, 90 mol% or more is a p-phenylene sulfide unit.
When the unit is less than 30 mol%, for example,

[0008]

[Chemical 1]

Although it is acceptable to include the above as a copolymerization component, the content of these copolymerization components is more preferably 10 mol% or less. In particular,

[0010]

[Chemical 2]

The polyfunctional copolymer component having 3 or more functional units, such as, 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 alkali sulfide and p-dihalobenzene in a polar solvent at 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 or alkali metal carboxylate is added to obtain 230
Most preferably, the reaction is carried out at a temperature of 280 to 280 ° C. The pressure in the polymerization system and the polymerization time are appropriately determined depending on the kind and amount of the auxiliary agent used and the desired degree of polymerization.

In order to maintain the electrical insulation performance of the finally obtained film, polymerized polymer (generally in powder form) is used.
Is preferably washed with water or an organic solvent that does not contain metal ions to remove by-product salts, polymerization aids and the like during the polymerization to keep the ionic carrier concentration sufficiently low. In this case, the total inorganic content in the polymer is 5,000 ppm or less, calcium 1
It is preferably 000 ppm or less and sodium 500 ppm or less.

When the polymer is in the form of powder, it can be extruded into a gut shape using a twin-screw extruder and pelletized in advance. Further, 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 the PPS used for the heat treatment is 315.6.
The melt index at ℃ is 0.5g / 10min or more,
It is necessary to be 200 g / 10 minutes or less. It is preferably 5 g / 10 minutes or more and 150 g / 10 minutes or less, more preferably 10 g / 10 minutes or more and 120 g / 10 minutes or less. When the melt index is less than 0.5 g / 10 minutes, extrusion becomes difficult, which is not preferable. On the other hand, 20
When it exceeds 0 g / 10 minutes, the uniformity of the thickness is poor when extruded into a film or the like, which is not preferable.

In the present invention, the heat treatment temperature is not lower than 200 ° C. and not higher than the melting point of PPS. The temperature is preferably 220 ° C. or higher and 5 ° C. lower than the melting point of PPS, and more preferably 230 ° C. or higher and 5 ° C. lower than the melting point of PPS. When the heat treatment temperature is lower than 200 ° C., it is difficult to reduce low molecular weight substances that cause stains on the die, which is not preferable. On the other hand, if it exceeds the melting point, it will be melted and adhered to the apparatus, and thermal deterioration will increase, which is not preferable. Further, in the molten state, the effect of reducing low molecular weight substances becomes small, so it is necessary to carry out in the solid state.

In the present invention, the atmosphere for heat treatment should 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 is 2
When heat treatment is performed in an atmosphere exceeding 0 mmHg, PP
Oxidative cross-linking of S occurs, which makes the molded product brittle, which is not preferable. The inert atmosphere is used to replace air with PPS and a chemically inert gas to remove low molecular weight substances from the system at the same time, and generally, the pressure is reduced or economically inexpensive. It is preferable to use a nitrogen stream.
Of course, the total pressure may be any pressure as long as the oxygen partial pressure is 20 mmHg or less.

In the present invention, the difference (η−η ₀ ) between the melt index η ₀ of PPS before heat treatment and the melt index η after heat treatment is −30 ≦ 100 × (η−η ₀ ) / η ₀ It is preferable that the heat treatment is performed within the range of ≦ 30 (1). P
The melt index of PS varies depending on the degree of polymerization of the polymer, the terminal group, and the degree of branching, and these vary depending on the operating conditions such as the type of apparatus used for heat treatment, treatment temperature, time, and atmosphere. However, within the oxygen partial pressure range specified in the present invention, the change in the melt index of the polymer can be reduced even if the heat treatment is performed. In addition to the heating temperature and pressure within the above range, the heating time is usually 3
It is preferably 0 minutes or more and 10 hours or less.

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

The shape of PPS in the heat treatment may be powder or pellet, but is preferably gut for easy handling. Further, it may be one obtained by shredding film scraps once formed into a film.

Further, in the present invention, P which is subjected to heat treatment
PS is preferably crystallized in order to avoid fusion during heat treatment, and has a crystallinity of 30% or more, more preferably 35% or more.

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

[0023]

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

(1) Strength and Elongation The breaking strength and breaking elongation of a sample having a width of 10 mm and a test length of 50 mm were determined by a Tensilon type tensile testing machine and n = 5.
Was calculated as the average value of

(2) Melt index: 5 kg load, 3 according to ASTM D-1238-70
A value measured at 15.6 ° C. and expressed in units of g / 10 minutes.

(3) Melting point It was measured using a differential scanning calorimeter (DSC-2 type).

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

(5) Fouling of the die The judgment was made according to the following criteria based on the amount of low molecular weight substances attached near the die during film formation and the occurrence of film breakage resulting from it. ◯: Even after 10 hours of film formation, there is almost no adhesion to the die and the film does not break. Δ: After film formation for 10 hours, there was a deposit on the die, during which film breakage occasionally occurred. ×: A large amount of deposits on the die during film formation for several hours caused frequent film breakage, and the die was cleaned to continue film formation.

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

101 mol of p-dichlorobenzene and 8 liters of NMP were added to the dehydrated system, and 170
Nitrogen was pressurized to 3 kg / cm ² at ℃ and the temperature was raised to 26
Polymerization was carried out 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 net having a 150 mesh opening.

This polymer was washed 5 times with distilled water at 90 ° C. and then dried at 120 ° C. under reduced pressure to give a melting point of 283.
A white granular PPS at ℃ was obtained.

(2) Pelletization of PPS Next, the obtained granular PPS was blended with calcium carbonate having an average particle size of 1.2 μm so as to be 0.7% by weight with respect to PPS, and the mixture was heated to 320 ° C. with a biaxial kneader. Melted and kneaded, discharged from the strand, and cut to obtain 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 (2) above were heated at 180 ° C. for 1 hour.
It was dried under reduced pressure of 0 mmHg or less for 2 hours for pre-crystallization. The crystallinity of the obtained PPS pellets was 40%. Next, the pellets were placed in a rotary dryer, and pressure reduction and nitrogen filling were repeated to replace the pellets with nitrogen.
It heat-processed at 0 degreeC and oxygen partial pressure of 1 mmHg (total pressure of 5 mmHg) for 4 hours. The melt index of the PPS pellets after the heat treatment was 70 g / 10 minutes.

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

Next, the sheet is caused to run in contact with a plurality of heating rolls having a surface temperature of 95 ° C., and is 3.7 in the longitudinal direction between the heating rolls and cooling rolls having different peripheral speeds and having different peripheral speeds of 30 ° C. The film was stretched twice. This uniaxially stretched sheet was stretched 3.7 times in the longitudinal direction at 100 ° C. using a tenter,
Then, it heat-processed at 260 degreeC for 10 second (s), and the biaxially-stretched PPS film of thickness 4micrometer was obtained. In this film formation, the film did not break once in 10 hours, and there was almost no deposit on the die after 10 hours, and the stain was extremely small. The mechanical properties of the obtained film were also good.

Table 1 shows a list of heat treatment conditions, film forming results and characteristics of the obtained film.

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

Comparative Example 4 The white granular PPS obtained in (1) of Example 1 was agitated for 30 minutes at 70 ° C. for 30 minutes with NMP in an amount of 5 times by weight, and then filtered. It was washed 8 times with and dried at 150 ° C. using a vacuum dryer. The melting point of the obtained polymer was 284 ° C.

Next, the obtained granular PPS was blended with calcium carbonate having an average particle size of 1.2 μm so as to be 0.7% by weight with respect to PPS, and melt-kneaded at 320 ° C. in a twin-screw kneader to form a strand. 2 ~ 3mm diameter after discharging and cutting,
The PPS pellets were 3 to 4 mm long.

The obtained PPS pellets were placed at 180 ° C. for 1
It was dried under reduced pressure of 0 mmHg or less for 2 hours. Obtained P
The crystallinity of PS pellets was 40%.

Next, the obtained PPS pellets were fed to an extruder, and subsequently discharged from a T-die type die provided and rapidly cooled by a cooling rotary drum to give a substantially amorphous thickness 5
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 is 3.7 in the longitudinal direction between the heating roll group and the cooling rolls having different peripheral speeds of 30 ° C. The film was stretched twice. This uniaxially stretched sheet was stretched 3.7 times in the longitudinal direction at 100 ° C. using a tenter,
Then, it heat-processed at 260 degreeC for 10 second (s), and the biaxially-stretched PPS film of thickness 4micrometer was obtained.

Since film tears frequently occurred after film formation for 6 hours, the mouthpiece was cleaned, but the film was torn four times thereafter.

The heat treatment conditions, the film forming results and the characteristics of the obtained film are listed in Table 1.

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

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

[0047]

[Table 1]

[0048]

EFFECTS OF THE INVENTION The PPS obtained according to the present invention has a reduced amount of low-molecular weight substances which cause stains on the die, and therefore, tears during film formation are reduced, so that the die may be cleaned less frequently. The feature is that the film forming property is significantly improved.

As described above, PP obtained by the method of the present invention
S can be particularly effectively utilized when S is melt extruded to form an unstretched sheet or a uniaxially stretched or biaxially stretched film. Moreover, since the amount of low molecular weight substances is small, the obtained film is excellent not only in electrical characteristics and mechanical characteristics, but also in uniformity of these characteristics. Suitable for various release materials and circuit boards. Further, it can be effectively applied to the field of fibers and other molding materials.

Claims (1)

[Claims] 1. A polyphenylene sulfide having a melt index of 0.5 g / 10 minutes or more and 200 g / 10 minutes or less at a temperature of 315.6 ° C., and an oxygen partial pressure of 20 mmHg.
A method for producing a polyphenylene sulfide, which comprises performing a heat treatment in a temperature range of 200 ° C. or higher and a melting point or lower in the following inert atmosphere.