JPH05140329A - Method for curing polyphenylene sulfide - Google Patents

Abstract

PURPOSE:To carry out curing capable of providing a cured material having improved impact resistance, etc., by oxidizing and crosslinking a poly(p- phenylene sulfide) having a zero shear viscosity before oxidation and crosslinking of >= a specific value until a zero shear viscosity reaches >= a specific value. CONSTITUTION:Powder of a poly(p-phenylene sulfide) before oxidation and crosslinking having >=800, preferably >=1,000 zero shear viscosity (poise unit) at 300 deg.C is oxidized and crosslinked in oxygen, ozone or a gas containing oxygen and ozone at >=200 deg.C to <the melting point, preferabiy 220-270 deg.C preferably by using a ribbon blender until a zero shear viscosity after oxidation and crosslinking reaches >=50,000, preferably >=70,000 while controlling temperature and time during crosslinking to produce a poly(p-phenylene sulfide) improved in impact resistance and tensile elongation at break.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a process for producing PPS having improved impact resistance and tensile elongation at break.

[0002]

2. Description of the Related Art PPS is known as a high performance engineering plastic having excellent chemical resistance, heat resistance and flame retardancy.

Conventionally, PPS is produced by a method based on Japanese Patent Publication No. 45-3368, etc., but the polymer obtained has a low molecular weight and does not have sufficient strength, and since it has a low viscosity, it is formed into pellets. It is known that even manufacturing is difficult. Therefore, a method of increasing the molecular weight by increasing the molecular weight by oxidizing and cross-linking the low molecular weight substance of the polymer synthesized in the air at a temperature below its melting point, and improving the moldability and processability of the molded article, is currently available. A polymer having a high molecular weight obtained by this method is industrially used.

However, the high molecular weight polymer obtained by this oxidative crosslinking has a serious drawback that it has poor toughness, that is, tensile elongation at break and tensile strength are low. Therefore, in order to improve such drawbacks, many improvements in the polymerization process have been proposed. For example, JP-A-50-8469
In Japanese Patent Publication No. 8, an alkali metal carboxylate is added as a polymerization catalyst. However, this production method requires not only a special polymerization catalyst but also a high cost such as the need for a polymer purification step for removing the polymerization catalyst in PPS which does not have a suitable solvent for dissolving at 200 ° C or lower. Next is a problem.

Further, in Japanese Patent Laid-Open No. 62-197422, PPS having a melt flow rate below a certain value is oxidatively crosslinked to a melt flow rate below a certain value, and the melt before and after oxidative crosslinking is melted. A method for producing PPS by oxidative crosslinking so that the ratio of flow rate values is within a certain range has been proposed. However, this is for the purpose of preventing the occurrence of weld cracks, and is insufficient for improving the toughness and impact resistance.

[0006]

The present invention is based on the conventional PPS.
The present invention improves the brittleness, which has been known as a defect of (1), and provides PPS having excellent impact resistance and tensile elongation at break.

[0007]

In order to solve the above problems, the present inventors have studied the zero shear viscosity before and after oxidative crosslinking, impact resistance and tensile elongation at break, and as a result, the zero shear viscosity and mechanical properties are deep. It was found that even if the zero shear viscosity after oxidative crosslinking is the same, the mechanical properties of PPS, especially the tensile elongation at break, are significantly increased at a certain zero shear viscosity before oxidative crosslinking. It has been found that the present invention has been improved and that it becomes non-destructive in the Izod impact test, and has reached the present invention.

That is, according to the present invention, PPS having a zero-shear viscosity (hereinafter abbreviated as η0 ') of 800 or more before oxidative crosslinking has a zero-shear viscosity (hereinafter abbreviated as η0) of 50,000 after oxidative crosslinking.
P characterized by oxidative cross-linking until reaching the above
The present invention relates to a PS curing method.

The present invention will be described in detail below.

The "zero-shear viscosity" in the present invention is a melt viscosity in a low shear rate state in which a molten polymer shows Newtonian flow, and is a cone-plate type rotational viscometer, for example, Weisenberg Leo manufactured by Sangammo Ltd. in the UK. It can be measured using a goniometer R20 or the like.

In the present invention, a cone-plate type Weisenberg Gregogoniometer is used, in a nitrogen atmosphere, at a constant flow rate of 0.01 to 100 (sec ⁻¹ ) in a shear rate range of 300.
Measurement is performed in the temperature range of ~ 380 ° C, and the WLF is measured.
(ML Williams-RE Landel-
J. D. The zero shear viscosity was determined by superimposing it on 300 ° C. using the Ferry equation.

The PPS before oxidative crosslinking used in the present invention has the general formula

[0013]

[Chemical 1] It is composed of a repeating unit represented by.

And, such PPS has η0 ′ ≧ 800,
It preferably has η0 ′ of η0 ′ ≧ 1000 and is not particularly limited as long as it can be obtained by a known method. However, if η0 ′ <800, the effect of improving the impact resistance and tensile elongation at break according to the present invention is not exhibited, which is not preferable.

As a concrete method for producing such PPS,
For example, (1) Reaction of halogen-substituted aromatic compound with alkali sulfide (US Pat. No. 2,513,188, JP-B-4)
No. 4-27671 and Japanese Examined Patent Publication No. 45-3368), (2) Coupling reaction in the coexistence of thiophenols with an alkali catalyst or a copper salt (US Pat. No. 327416).
5 and British Patent No. 1160660),
(3) A binding reaction of an aromatic compound with sulfur chloride in the presence of a Lewis acid catalyst (Japanese Patent Publication No. 46-27255 and Belgian Patent No. 29437).

Particularly, Japanese Examined Patent Publication No. 52-1 which meets the object of the present invention.
2240, Japanese Patent Publication No. 54-8719, Japanese Patent Publication No. 53-25588, Japanese Patent Publication No. 57-334,
JP-A-55-43139, U.S. Pat. No. 4,350,81
It is preferably obtained by a method for producing a high molecular weight PPS as described in JP-A No. 0 and US Pat. No. 4,324,886.

In the present invention, the oxidative crosslinking is carried out by controlling the temperature and time during the oxidative crosslinking of the limited η0 ′ PPS obtained by the above-mentioned manufacturing method until η0 ≧ 50000, preferably η0 ≧ 70000. .. Such η0 is 5
If it is less than 0000, the effect of the present invention is reduced, which is not preferable.

Such oxidative crosslinking can be carried out using various known methods. For example, a ribbon blender,
Examples include oxidative crosslinking using a fluidized bed, an oven, and a container-rotating mixer. Among them, a method using a ribbon blender is preferable, and PPS is made into powder and is used in oxygen, ozone, or a gas containing these.

The temperature at which the oxidative crosslinking is carried out is 200 ° C. or higher and lower than the melting point, and preferably 220 in view of productivity.
C. or higher and lower than 270.degree. If the temperature is lower than 200 ° C, the curing rate is slow and not practical, and if the temperature is higher than the melting point, fusion of PPS particles may occur.

The PPS produced according to the present invention also includes
Within the scope of the present invention, thermoplastic elastomers such as ethylene-propylene-ethylidene norbornene copolymer (EPDM rubber), ethylene-propylene copolymer (EP rubber), ethylene-butene-1 copolymer, styrene. It is also possible to add a butadiene block copolymer, a styrene block copolymer elastomer, an amide elastomer, an ester elastomer, a urethane elastomer or the like, or a rubber polymer such as a conjugated diene rubber or an acrylic rubber. Further, polyesters such as polyethylene, polystyrene, polybutene, polymethylstyrene, polyvinyl acetate, polyvinyl chloride, polyacrylic acid ester, polymethacrylic acid ester, polyacrylonitrile, polyethylene terephthalate, polybutylene terephthalate, polyarylate, nylon 6, nylon 66, nylon 46, nylon 1
2, Nylon 11, amorphous nylon, polyamide such as aromatic nylon, polyurethane, polyacetal, polycarbonate, polyphenylene ether, polysulfone,
Polyether sulfone, polyallyl sulfone, polyphenylene sulfide sulfone, PPS, polyether ketone, polyether ether ketone, polyphenylene sulfide ketone, polyimide, polyamide imide, silicone resin, phenoxy resin, fluorine resin, homopolymer such as epoxy resin, random It is also possible to add thermoplastic resins and thermosetting resins such as polymers or blocks, graft copolymers and mixtures thereof.

If necessary, glass fibers, carbon fibers, ceramic fibers such as alumina fibers, aramid fibers,
Reinforcing fillers such as wholly aromatic polyester fibers, metal fibers, potassium titanate whiskers, silicon carbide whiskers, calcium carbonate, mica, talc, silica, barium sulfate, calcium sulfate, kaolin, clay, pyroferrite, bentonite, sericite , Zeolite, nepheline sinite, attapulgite, wollastonite,
Ferrite, calcium silicate, magnesium carbonate, dolomite, antimony trioxide, zinc oxide, titanium oxide,
Magnesium oxide, iron oxide, molybdenum disulfide, graphite,
Inorganic fillers such as gypsum, glass beads, glass powder, glass balloons, quartz and quartz glass, and organic and inorganic pigments can also be blended.

As the glass fiber, for example, a fiber length of 1.5
-12 mm, chopped strands having a fiber diameter of 3 to 20 µ, milled fibers having a fiber length of 30 to 500 µ and fiber diameter of 3 to 20 µ, and glass flakes and glass powder having a mesh of 325 or less can be mentioned.

Further, plasticizers such as aromatic hydroxy derivatives, mold release agents, silane coupling agents, titanate coupling agents, lubricants, heat resistance stabilizers, weather resistance stabilizers, crystal nucleating agents, foaming agents, rust preventive agents, Ion trap agents, flame retardants, flame retardant aids, antioxidants, ultraviolet absorbers, hindered amine light stabilizers, colorants, and metal thiophosphinic acid salts as crosslinking accelerators for the purpose of controlling the degree of crosslinking of PPS. A crosslinking inhibitor such as dialkyltin dicarboxylate or aminotriazole may be added if necessary.

The PPS produced by the present invention can be pelletized by adding various components described above and various known methods. For example, the hot melt kneading method using a single-screw extruder, a twin-screw extruder, a kneader, a Brabender, etc. is most preferable.
The kneading temperature at this time is not particularly limited, but usually can be arbitrarily selected from 200 to 400 ° C.

[0025]

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 (Synthesis of PPS) In a reactor having an inner volume of 530 liter equipped with a stirrer, a dehydration tower and a jacket, 110 liter of N-methylpyrrolidone and sodium sulfide (purity: Na ₂
S 60.2 wt%) 61.1 kg was charged and heated with a jacket under stirring until the internal temperature reached about 200 ° C.
Distillation was performed through a dehydration tower. At this time, 13.5 liters of an extract containing mainly water was distilled off. Then p
-Adding 68.7 kg of dichlorobenzene and 48 liters of N-methylpyrrolidone, heating to 225 ° C over 2 hours, reacting at 225 ° C for 2 hours, and then heating up to 250 ° C over 30 minutes. Then, the mixture was further reacted at 250 ° C. for 3 hours.

After completion of the reaction, the reaction mixture was transferred to a solvent collector equipped with a stirrer, a jacket and a decompression line. At this time, 30 liters of N-methylpyrrolidone were added.
Then, the mixture was heated under reduced pressure to distill 210 liters of a distillate mainly composed of N-methylpyrrolidone.

Subsequently, 200 liters of water was added to form a water slurry, which was heated and stirred at 80 ° C. for 15 minutes, and then centrifuged to recover the polymer.

Further, the polymer was returned to the solvent recovery device, 200 liters of water was added, the mixture was heated and stirred at 100 ° C. for 30 minutes, and after cooling, the polymer powder was recovered by a centrifuge. This operation was repeated twice.

The obtained polymer was transferred to a ribbon blender with a jacket and dried. The polymer obtained in this way had η0 ′ of 745, which was determined by PPS-
I.

Reference Example 2 Instead of 68.7 kg of p-dichlorobenzene in Reference Example 1, 69.0 kg of P-dichlorobenzene was used.
Reference Example 1 except that the reaction time at 250 ° C. was 4 hours
PPS was synthesized in the same manner as in. The polymer obtained in this way had η0 ′ of 1170, which was measured by PPS-II.
And

Examples 1-5, Comparative Examples 1-7 15 kg of the PPS obtained in Reference Examples 1 and 2 were charged into a ribbon blender having an internal capacity of 110 liters, and the rotation speed was 60 rp.
agitate at 10 m / min and blow air at 10 liters / min.
Oxidative crosslinking was carried out at 5 ° C. for different times.

Table 1 shows η0 ', η0 and oxidative crosslinking time.

The PPS thus obtained is
A co-rotating twin-screw extruder set at 340 ° C. was used to melt-knead the screw at a screw rotation speed of 200 rpm, and the extruded strand was pelletized. The pellets obtained here were supplied to a screw in-line type injection molding machine set at 270 to 330 ° C., and a test piece for a tensile test and an Izod impact test were injection-molded under a mold temperature of 135 ° C. Tensile test (AST
MD-638), Izod impact test (ASTMD-2
56) was performed. The results are shown in Table 1.

[0035]

[Table 1] Further, in order to visually show the effect of the present invention, a graph in which the tensile elongation at break is plotted against the zero shear viscosity is shown in FIG.

[0036]

The PPS produced according to the present invention is excellent in impact resistance and tensile elongation at break. Therefore, various conventionally known methods can be applied to printed wiring boards, electronic component sealing materials, various connector components, and heat resistant paints. , Thin-walled molded articles, fibers, sheets, films, tubes and the like can be molded into various shaped articles, and injection molding, extrusion molding, blow molding, foam molding and other processing methods are possible, especially extrusion molding, It is preferably used for blow molding. As a specific field of application, it can be widely used as a molding material having excellent heat resistance, flame retardancy and molding processability in the field of industrial materials such as automobiles, electricity, electronics and machinery.

[Brief description of drawings]

FIG. 1 shows a PP obtained according to an example of the present invention and a comparative example.
It is a figure which shows the zero shear viscosity of S, and the relationship of tensile elongation at break.

Claims (1)

[Claims] 1. Zero-shear viscosity (unit POI at 300 ° C.)
PPS characterized by carrying out oxidative crosslinking of poly (p-phenylene sulfide) (hereinafter referred to as PPS) having an SE of 800 or more before oxidative crosslinking until the zero shear viscosity at 300 ° C. after oxidative crosslinking reaches 50,000 or more. Curing method.