JP2717566B2 - Hue-stabilized polyarylene sulfide resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyphenylene sulfide resin (hereinafter referred to as "PP
S ") and the stabilization of the hue during melt molding of other polyarylene sulfide resins. More specifically, the present invention relates to a PPS or other polyarylene sulfide resin composition in which coloring during melt molding due to decomposition of a polymer or thermal crosslinking is prevented.

PPS is a thermoplastic resin with excellent properties such as heat resistance, chemical resistance, and dimensional stability of molded products.
Used as electric / electronic parts, mechanical parts, etc. However, the hue of these molded products is brown or
Or even if it is white, there is a phenomenon that it gradually changes to brown under high temperature, coloring is severely limited,
Applications were limited. On the other hand, application of PPS to heat-resistant films and fibers is also being studied. For these uses,
It is necessary that the polymer is linear and has a sufficiently high molecular weight, has little coloration, that is, is white, and has a small change in hue under high temperature.The conventional low molecular weight polymer is thermally crosslinked to increase the molecular weight. However, such a material had a drawback that sufficient physical properties could not be obtained and the product was colored brown. The present invention provides a polyarylene sulfide resin composition which solves these problems.

(Prior art)

Most of conventional PPSs having a relatively low molecular weight are subjected to a high temperature treatment in the presence of oxygen to cause crosslinking, branching reaction and the like to have a high molecular weight. PPS that has been increased in molecular weight by such a method is strongly colored,
There are many problems such as insufficient mechanical strength due to many cross-linked branched structures.

As a method for solving the above problems, a method using various polymerization auxiliaries during the polymerization reaction (JP-A-52-12240, JP-A-5-12240).
9-219332, U.S. Pat. No. 4,038,263), and a method in which after a certain degree of polymerization reaction is carried out, water is added, and the temperature is further raised to carry out the latter-stage polymerization (Japanese Patent Laid-Open No. 61-7332). ing. According to these methods, it is possible to increase the molecular weight while maintaining the linear structure without causing cross-linking, branching, and the like, and the generated PPS is also less colored. However, even when the thus obtained PPS having a linear structure and having a sufficiently high molecular weight and a small color is used, prior to molding, pelletization, which is usually performed industrially, that is, an extruder is used. When the powdered polymer is heated and melted in a cylinder and extruded into pellets, radicals and peroxides are generated under the influence of oxygen and the like, and coloring tends to occur, and it is difficult to obtain a molded product with less coloring. there were.

JP-A-47-1735 discloses a method for improving coloring during pelletization, in which an organic phosphinic acid such as phenylphosphinic acid or an organic phosphite such as dioctyl phosphite is added before pelletizing. Kaisho
No. 59-213759 proposes a method of adding one or more selected from amine derivatives, phenol derivatives, hydroquinone derivatives, catechol derivatives, phosphites, and alkylthioethers. Further, JP-A-63-
No. 159470 proposes a method of adding a phosphorus compound having a spiro ring. However, according to the study of the present inventors, in the case of these methods, the heat resistance of the coloring prevention agent is insufficient, and decomposition or volatilization occurs at a temperature of 300 ° C. or higher during pelletization, and the coloring prevention is prevented. The effect is not satisfactory, and the amount of gas during molding is abnormally large,
There is a problem that the decomposed product adheres to the vent portion of the mold as a dust. Further, it was found that a satisfactory coloring prevention effect could not be obtained unless the amount of the residual amide solvent, the amount of heavy metal ions and the amount of sodium ions in the PPS were reduced to a certain amount or less.

Further, Japanese Patent Application Laid-Open No. 62-97821 discloses that, during the polymerization reaction, a reactor in which the liquid contact part with the reaction solution is made of titanium is used, and after the reaction, an effective amount of a halo-substituted organic compound is added and the reaction is repeated. A method of reacting and stabilizing a molecular terminal is disclosed. However, in the case of this method, although a certain degree of anti-coloring effect can be obtained, it is not possible to obtain a white color or a color close to it without using a color-preventing agent together with reducing the amount of the residual organic amide solvent in the PPS to a certain amount or less. Have difficulty.

[Problems to be solved by the invention]

An object of the present invention is a polyarylene sulfide resin composition having high whiteness, capable of obtaining pellets having a small discoloration with time even at the time of melt molding and other high temperatures, and thus a molded article, and a resin which is obtained industrially advantageously. Providing a composition.

[Means for solving the problem]

The polyarylene sulfide resin composition of the present invention,
A polyarylene sulfide resin polymerized using an organic amide solvent as a polymerization medium and having an organic amide solvent content of 1,000 ppm or less, and 0.05 to 5 parts by weight of the following general formula based on 100 parts by weight of the polyarylene sulfide resin (I): [In the formula, R, R ′, R ″ are an aryl group or an alkyl group which may have a substituent, and R, R ′, R ″ may be the same or different. ] It is characterized by comprising at least one kind of the tertiary phosphine oxide represented by

The polyarylene sulfide resin stabilized in the present invention is a polymer substantially consisting of repeating units -RS- (R: aryl group). Preferably, a paraphenylene group as a repeating unit, And a paraphenylene group as a main component, and as a minor component, other arylene groups such as m. And a random copolymer and a block copolymer having the same. Further, these polyarylene sulfide resins may be a mixture. A particularly preferred resin is polyparaphenylene sulfide resin (PPS).

As the PPS, for example, PPS obtained by a method of reacting an alkali metal sulfide and a polyhalo aromatic compound in an organic amide solvent disclosed in JP-B No. 45-3368,
Various polymerization aids, for example, alkali metal carboxylate,
After reacting a high molecular weight PPS obtained by using an alkali metal salt of an aromatic carboxylic acid, an alkali metal halide or the like, an alkali metal sulfide with a polyhalo aromatic compound at 180 to 235 ° C. to 50 to 98% After adding water, further raising the temperature and reacting the PPS obtained by polymerization in two steps, the alkali metal sulfide and the polyhaloaromatic compound in an organic amide solvent, and washing with an organic amide solvent while heating. PPS obtained by removing the polymerization inhibitory substance and unreacted substance by further reacting at 200 to 260 ° C., and further polymerizing by adding a branching agent such as 1,3,5-trichlorobenzene during the reaction. Forked PPS
And the like. The tertiary phosphine oxides used as a coloring inhibitor in the present invention have good thermal stability and good acid resistance because the carbon of the aryl or alkyl group is directly bonded to the tertiary phosphine oxide. It can withstand the severe conditions during melt kneading and molding. As a measure of heat resistance, it is stable from 490 ° C to 700 ° C, depending on the type of the substituent, based on the temperature at which 50% weight loss is exhibited. Examples of such a tertiary phosphine oxide include trimethyl phosphine oxide (CH ₃ ) ₃ P (O), triphenyl phosphine oxide (C ₆ H ₅ ) ₃ P (O), and methyl ethyl phenyl phosphine oxide (CH ₃₎ (C ₂ H ₅₎
(C ₆ H ₅ ) P (O), dimethyl ethyl phosphine oxide (CH ₃ ) ₂ (C ₂ H ₅ ) P (O), triethyl phosphine oxide (C ₂ H ₅ ) ₃ P (O), methyl ethyl・ Pentylphosphine oxide (CH ₃ ) (C ₂ H ₅ ) (C ₅ H ₁₁ ) P
(O), tri-n-butyl phosphine oxide (n-C ₄ H ₉ ) ₃ P (O), tri-octyl phosphine oxide (n-C ₈ H ₁₇ ) ₃ P (O) and the like.

The amount of the tertiary phosphine oxide used in the present invention is based on 100 parts by weight of the polyarylene sulfide resin.
It is 0.05 to 5 parts by weight, preferably 0.1 to 1 part by weight. If the added amount of phosphine oxide is less than 0.05 parts by weight, the effect of preventing coloring is not sufficient, and if it exceeds 5 parts by weight, it is difficult to expect a further effect of preventing coloring, which is not preferable from an economic viewpoint.

It is appropriate to add the tertiary phosphine oxide to the polyarylene sulfide resin immediately before pelletizing or before the drying step which is the final step in the resin production process. Further, as a method of adding the tertiary phosphine oxides, using a conventional mixer such as a Henschel mixer, a ribbon blender, a method of directly mixing the resin and the tertiary phosphine oxides, or using an appropriate solvent A method of mixing and dissolving at room temperature or under heating, and then removing the used solvent by evaporation or the like. Solvents such as methanol, ethanol, acetone,
Organic solvents such as dioxane, benzene, toluene, tetrachloroethylene and chloroform can be used.
In addition, when adding at the stage of the wet cake before the drying process, since the wet cake contains a large amount of water,
Sodium oleate and other surfactants may be used to increase the mixing effect.

An organic amide solvent (eg, N-methyl-2-pyrrolidone) is usually used during the polymerization reaction to produce a polyarylene sulfide resin. However, if this amide solvent remains in the resin in a large amount, oxidation and decomposition during pelletization may occur. To form a chromophore to color the resin. In order to prevent this coloring, it is necessary to remove the organic amide solvent as much as possible, and the content of the organic amide solvent in the resin is 1,000 ppm or less. In particular, it is preferable to reduce the concentration to 500 ppm or less. When the content of the organic amide solvent is 1,000 ppm or less, coloring by the organic amide solvent at the time of pelletization hardly occurs, and a hue having a Hunter whiteness of 40% or more after pelletization can be obtained.

As a method for removing the organic amide solvent, it is preferable to wash the slurry after the reaction (a mixture of the polyarylene sulfide resin, by-product salt and the organic amide solvent) with the organic solvent. Examples of the organic solvent used include alcohols such as methanol, ethanol, and isopropanol;
Examples include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as benzene, toluene, and xylene; and halogenated hydrocarbons such as 1,1,2,2-tetrachloroethane, trichloroethylene, and carbon tetrachloride. As a washing method, it is preferable to add 1 to 2 times the amount of the organic solvent based on the weight of the slurry to the slurry after the reaction, and perform stirring and washing at a temperature of 20 to 120 ° C. under normal pressure or pressure for 0.5 to 1 hour. In order to reduce the amount of the organic amide solvent in the polyarylene sulfide resin to 1,000 ppm or less, the above operation must be repeated three to four times. Cleaning is preferably performed in a nitrogen gas stream. Although a method using water as a washing solvent is conceivable, it is difficult to remove the organic amide solvent taken into the resin particles, and the use of an organic solvent has a better washing effect.

The amount of the organic amide solvent in the polyarylene sulfide resin is determined by dissolving the resin in α-chloronaphthalene under heating,
The slurry formed by cooling is filtered, and the filtrate can be measured by a calibration curve method using a gas chromatograph equipped with an FID detector.

It is desirable that the amount of heavy metal ions in the polyarylene sulfide resin is as small as possible. Here, heavy metal ions refer to ions such as iron, nickel, chromium, molybdenum, and manganese, and mainly refer to iron ions. These heavy metal ions are mixed into the resin as impurities contained in the raw material and as ions eluted from a manufacturing apparatus such as a reactor. It is considered that when heavy metal ions are contained in the resin, a chelate compound is formed at the time of pelletization to form color. Therefore, the total content of heavy metal ions in the resin is 20 ppm
It is desirable to keep below.

In order to keep the total content of heavy metal ions in the polyarylene sulfide resin at 20 ppm or less, the liquid contact part of a manufacturing device such as a reactor is made of a non-ferrous metal (for example, titanium),
In addition, it is necessary to use an alkali metal sulfide (for example, sodium sulfide) and a polyhaloaromatic compound (for example, dichlorobenzene) that are substantially free from heavy metal ions as main raw materials.

The total content of heavy metal ions in the resin can be measured using an atomic absorption spectrophotometer after wet decomposing the resin with sulfuric acid and perchloric acid and diluting the resin with pure water.

SNa at the molecular end of polyarylene sulfide resin
There are those that are composed of a group or a SH group. When the molecular terminal is composed of an SNa group, the chromophore tends to be formed due to the promotion of the crosslinking reaction during pelletization and the presence of a small amount of an organic amide solvent and heavy metal ions. Therefore,
It is preferable to treat with an aqueous solution of an acid or an acid salt before pelletization to convert to an SH group. The amount of SNa groups can be measured by quantifying the sodium ion content in the resin from which the by-product salt has been sufficiently washed out and removed. Is desirably 100 ppm or less of sodium. The amount of sodium ions in the PPS is determined after sulfated ash of the resin.
After heating and burning in a muffle furnace and diluting with pure water, it can be measured by a calibration curve method using an atomic absorption spectrophotometer.

Hydrochloric acid is used as the acid used in the above treatment before pelletizing,
Phosphoric acid, sulfuric acid and the like can be mentioned, but in consideration of corrosion of the apparatus and prevention of deterioration of the resin, it is preferable to use a phosphate in which the aqueous solution is acidic. Examples of such phosphates include sodium dihydrogen phosphate NaH ₂ PO ₄ , sodium hexametaphosphate (NaPO ₃ ) n, and acid sodium hexametaphosphate N
amHn (PO ₃ ) m + n, HH sodium hexametaphosphate Nam
Hn (PO ₃ ) m + n, ammonium dihydrogen phosphate (NH ₄ ) H ₂
PO _{4 and the} like. Of these, sodium dihydrogen phosphate is particularly preferred. The treatment with these aqueous solutions is carried out at a concentration of 1 to 5% by weight under normal pressure or under pressure at 50 to 200 ° C.
Preferably, the reaction is carried out at a temperature of 100 to 150 ° C. with stirring for 0.5 to 3 hours.

[Action and effect of the invention]

In general, it is known to use a free radical chain inhibitor and a peroxide decomposer to prevent coloring during heating, and the former includes an amine derivative, a hydroquinone derivative, a catechol derivative, and the like. Include phosphites and alkylthioethers. However, the melting temperature of PPS requires a temperature of 300 ° C or higher, and the low-boiling point (low molecular weight) coloring inhibitor decomposes or volatilizes during melt molding and cannot be used unless it is used in large quantities. In addition, the types of coloring inhibitors that can be used are also limited. Further, when a coloring inhibitor having a high boiling point (high molecular weight) is used, the effect of preventing coloring is not satisfactory, and it is necessary to use a large amount. If a large amount of this coloring inhibitor is used, a crosslinking reaction is promoted during melt molding, and a phenomenon that the melt viscosity is increased is not preferred.

The coloring inhibitor used in the present invention, that is, the tertiary phosphine oxides, exhibits both effects of a free radical chain inhibitor and a peroxide decomposer, has heat resistance of 300 ° C. or more, and is sufficient in a small amount. It exhibits an effect of preventing coloring and does not cause undesired reactions such as a crosslinking reaction.

The resin composition of the present invention has high whiteness after pelletization,
In particular, in addition to mixing phosphine oxide and reducing the amount of organic amide solvent in the resin to 1,000 ppm or less, controlling the amount of heavy metal ions to 20 ppm or less, and pelletizing those treated with sodium dihydrogen phosphate aqueous solution Later hunter brightness is greater than 40%.

The polyarylene sulfide resin composition of the present invention, in which the hue is stabilized as described above, can be formed into heat-resistant films, sheets, fibers, and the like, as well as by injection molding, extrusion molding, and the like, in automobile parts, electric / electronic parts, and mechanical parts. Etc. can be formed.

The polyarylene sulfide resin composition of the present invention contains an ultraviolet absorber, a metal deactivator, a coloring agent, a lubricant, a crystal nucleating agent, a powder filler such as carbon black, calcium carbonate, and silica powder, carbon fiber, glass fiber, and the like. Can also be blended.

Further, the resin composition of the present invention is polycarbonate, polyphenylene oxide, polysulfone, polyacetal,
It can also be used as a mixture with one or more synthetic resins such as polyimide, polyamide, polystyrene, polyester and ABS.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to examples.

In the examples, the hue (Hunter whiteness) and melt viscosity of the resin were measured by the following methods and conditions.

Hue The hue of the resin is a color difference meter [TC-8600 type, manufactured by Tokyo Denshoku Co., Ltd.]
Was evaluated by Hunter brightness measured using A resin sample for Hunter whiteness measurement was prepared by the following method. That is, a twin-screw extruder equipped with a nitrided steel cylinder was used to pelletize at a temperature of 300 ° C., and the pellets were preheated at 325 ° C. for 3 minutes in a nitrogen stream using a hot press, and further heated at 325 ° C. for 1 hour. An amorphous sheet of about 2 mm obtained by pressing to form a sheet and quenching it was used as a sample.

Melt Viscosity The pellets obtained in the above section on determination of hue were measured using a flow dester (CFT-500, Shimadzu Corporation). Temperature 300 ° C, preheating 6 minutes, load 20kg / cm ² , nozzle 1φ
× 10mm.

12.8 kg (purity 61.49%) of flaky sodium sulfide in a titanium-lined autoclave of Examples 1-4 and Comparative Examples 1-3 100, N-methyl-2-
30 kg of pyrrolidone was charged, and the mixture was heated and stirred under a nitrogen stream until the internal temperature reached 204 ° C. to be dehydrated. The amount of water in the effluent (9.86 kg) was 29.8% by weight. The loss as hydrogen sulfide during the dehydration step was 0.60 mol% in terms of sodium sulfide.
After completion of the dehydration, the mixture was cooled to 160 ° C and p-dichlorobenzene 146.2
6 kg was dissolved in 10 kg of N-methyl-2-pyrrolidone and added, and the pressure was increased to 1 kg / cm ² G with nitrogen gas.
After reacting at 5 ° C. for 5 hours and further at 250 ° C. for 2 hours, the reaction mixture was cooled to 150 ° C., and heated under pressure using a 400 mesh wire mesh. 50 kg of N-methyl-2-pyrrolidone was added to the obtained solid, and the mixture was stirred and washed at 150 ° C. for 30 minutes under a nitrogen stream, and then heated and pressurized. Repeat the same washing and over-operation
The solid content was transferred to the autoclave after
After addition of 40 kg of methyl-2-pyrrolidone and replacement with nitrogen, 24
Polymerization reaction was performed at 0 ° C. for 4 hours.

After cooling to 150 ° C., 50 kg of methyl ethyl ketone was added to the solid content, and the mixture was stirred and washed at 70 ° C. for 30 minutes, followed by hot pressurization. Thereafter, the same washing and overoperation were performed three times to remove the remaining N-methyl-2-pyrrolidone. After the obtained solid was dried under the conditions of 60 mmHg and 120 ° C., the solid was transferred to the autoclave, 40 kg of pure water and 0.8 kg of sodium dihydrogen phosphate dihydrate were added, and the mixture was washed with water at 150 ° C. for 1 hour and filtered. . Washing with water was repeated until the salt disappeared, and dried to obtain 10.3 kg of powdered PPS. Its melt viscosity was 4250 poise.

A predetermined amount of a solution in which phosphine oxide shown in Table 1 was dissolved in methanol as a coloring inhibitor was added to the PPS, and the mixture was stirred well and then dried to remove methanol. Table 1 shows the quality and physical properties of the obtained PPS.

Example 5 54.45 g of 1,3,5-trichlorobenzene (p-
0.3 mol% based on dichlorobenzene),
After the completion of the reaction, 10.3 kg of powdery PPS was obtained in the same manner as in Example 1 except that washing with N-methyl-2-pyrrolidone and polymerization were not performed. Its melt viscosity was 2,300 poise.

A solution in which a predetermined amount of triphenylphosphine oxide was dissolved in methanol as a coloring inhibitor was added to the PPS, and the mixture was stirred well and then dried to remove methanol. Table 1 shows the quality and physical properties of the obtained PPS.

Examples 6 and 7 6.1 kg of water was added to a reaction solution slurry obtained by reacting in the same manner as in Example 1, and the temperature was further increased to 250 ° C under a nitrogen stream.
The reaction was performed for 10 hours. After cooling to 150 ° C., the mixture was filtered, 50 kg of methyl ethyl ketone was added to the solid, and the mixture was stirred and washed at 70 ° C. for 30 minutes, and then heated and pressurized. Thereafter, the same washing and overoperation were performed three times to remove the remaining N-methyl-2-pyrrolidone. Thereafter, the same treatment as in Example 1 was carried out, and PPS on the powder 10.
2 kg was obtained. Its melt viscosity was 1,850 poise.

A solution in which a predetermined amount of triphenylphosphine oxide was dissolved in methanol was added to the PPS, mixed well, and then dried to remove methanol. Table 1 shows the quality and physical properties of the obtained PPS.

Comparative Examples 4 to 6 To the powdered PPS obtained in Example 1 were added a solution in which a coloring inhibitor other than phosphine oxide was dissolved in acetone, and the mixture was thoroughly stirred, followed by drying to remove acetone.
Table 1 shows the quality and physical properties of the obtained PPS.

As can be seen from the results in Table 1, a resin having high Hunter whiteness can be obtained by blending a tertiary phosphine oxide as a coloring inhibitor. In particular, when the amount of residual NMP, the amount of heavy metal ions and the amount of sodium ions are lower than the above-mentioned predetermined amounts, the Hunter whiteness is 40% or more. That is, while the hunter brightness was 24% when the tertiary phosphine oxide was not added (Comparative Example 1), it was 50% when the triphenylphosphine oxide was added at 0.5 pHR (Example 2). It is clear that there is no increase in melt viscosity during pelletization.

2,6-di- as a colorant which has been widely used in the past
Hunter whiteness when tertiary butyl-p-cresolt and triphenyl phosphite are used in combination (Comparative Example 6) is inferior to that when tertiary phosphine oxides are used, and the melt viscosity when pelletized is low. You can see that it is rising.

Claims (4)

(57) [Claims] 1. A polyarylene sulfide resin polymerized using an organic amide solvent as a polymerization medium and having an organic amide solvent content of 1,000 ppm or less, and 0.05 to 5 parts by weight based on 100 parts by weight of the polyarylene sulfide resin. Of the following general formula (I): [In the formula, R, R 'and R "are an aryl group or an alkyl group which may have a substituent, and R, R' and R" may be the same or different. ] A polyarylene sulfide resin composition having a stable hue, comprising at least one tertiary phosphine oxide represented by the following formula: 2. The composition according to claim 1, wherein the polyarylene sulfide resin is a polyphenylene sulfide resin. 3. The composition according to claim 1, wherein the total content of heavy metal ions in the polyarylene sulfide resin is 20 ppm or less. 4. A polyarylene sulfide resin which is treated at a temperature of 50 to 200 ° C. with an aqueous solution of at least one phosphate in which the aqueous solution is acidic.
4. The composition according to any one of 3.