JP2676086B2 - 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 composition of PPS or other polyarylene sulfide resin in which coloration during melt molding due to polymer decomposition, thermal crosslinking or the like 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 was dark brown, and the coloring was extremely limited, and the applications were limited.
On the other hand, application of PPS to films and fibers is also under consideration. These applications require linearity and a sufficiently high molecular weight and less color, i.e. white, and conventional low molecular weight polymers that are thermally crosslinked to increase the molecular weight are sufficient. It had the drawback that it could not be obtained with physical properties and was colored dark 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, etc., and the produced 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. However, according to the studies by the present inventors, in the case of these methods, the heat resistance of the coloring inhibitor is insufficient, and the temperature at the time of pelletization
Decomposition or volatilization occurs at 300 ° C or higher, and the effect of preventing coloration is not satisfactory, and the amount of residual amide solvent, the amount of heavy metal ions and the amount of sodium ions in PPS can be satisfied unless they are reduced to a certain amount or less. It was found that the coloring prevention effect could not be obtained.

Further, in Japanese Patent Laid-Open No. 62-97821, a reactor in which the liquid contacting part with the reaction liquid is composed of titanium is used during the polymerization reaction, and after the reaction, an effective amount of a halo-substituted organic compound is added and re-formed. Methods of reacting and stabilizing less than a molecule are 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 to provide a polyarylene sulfide resin composition which is prevented from being colored during melt-molding and is capable of obtaining pellets with high whiteness and thus molded articles, which is industrially advantageous. It is in.

[Means for solving the problem]

The polyarylene sulfide resin composition of the present invention,
Polyarylene sulfide resin and 0.05 to 5 parts by weight of the following formula based on 100 parts by weight of the polyarylene sulfide resin: It is characterized by comprising 3,4,5,6-dibenzo-1,2-oxaphosphane-2-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 is used as a repeating unit, and a formula And a polymer represented by the formula (1), which contains a poraphenylene group as a main component, and a minor component, other arylene group such as m-phenylene group. O-phenylene group Alkyl-substituted phenylene group p, p'-diphenylene sulfone group p, p'-biphenylene group p, p'-diphenylene ether group p, p'-diphenylenecarbonyl group Naphthalene group Random copolymers and block copolymers having Moreover, 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 assistants, for example, alkali metal carboxylate, alkali metal salt of aromatic carboxylic acid, high molecular weight PPS obtained using alkali metal halide, etc. 50 at 235 ° C
After reacting up to 98%, water is added, the temperature is further raised, and PPS, an alkali metal sulfide obtained by polymerization in two steps, and a polyhaloaromatic compound are reacted in an organic amide solvent. The polymerization inhibitory substance and unreacted substances are removed by washing with an amide solvent while heating, and PPS obtained by further reacting at 200 to 260 ° C., and further, a branching agent such as 1,3,5-trichlorobenzene during the reaction is used. And branched PPS obtained by addition and polymerization.

The coloring preventing agent used in the present invention, that is, 3,4,5,6-dibenzo-1,2-oxaphosphane-2-oxide (hereinafter abbreviated as “DOPO”) is added in an amount of 100% by weight of the polyarylene sulfide resin. The amount is 0.05 to 5 parts by weight, preferably 0.1 to 1 part by weight. If the amount of DOPO added is 0.05 parts by weight or less, the effect of preventing coloration is not sufficient, and if it exceeds 5 parts by weight, it is difficult to expect a further effect of preventing coloration and it is not preferable from an economic standpoint.

It is suitable to add DOPO to the polyarylene sulfide resin immediately before pelletizing or before the drying step which is the final step of the resin production process. Further, as a method for adding DOPO, a resin is mixed with DOPO as it is by using an ordinary mixer such as a Henschel mixer or a ribbon blender, or a suitable solvent is used and mixed at room temperature or under heating. A method of dissolving and then removing the used solvent by evaporation or the like is adopted.
As the solvent, methanol, ethanol, acetone, dioxane, benzene, toluene, tetrachloroethylene,
An organic solvent such as chloroform can be used. When the wet cake is added at the stage before the drying step, since the wet cake contains a large amount of water, sodium oleate and other surfactants may be used to enhance 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 preferably 1,000 ppm or less, particularly 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 of using water as a cleaning solvent can be considered, it is difficult to remove the organic amide solvent taken in the resin particles, and the cleaning effect is better when an organic solvent is used.

The amount of the organic amide solvent in the polyarylene sulfide resin is the solvent of the resin in α-chlornaphthalene 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, the heavy metal ions refer to iron, nickel, chromium, molybdenum, and manganese ions, and mainly indicate iron. These heavy metal ions are mixed in the resin as impurities contained in the raw material and as ions eluted from the reactor and the filtration device. 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, it is desirable to keep the total content of heavy metal ions in the resin to 20 ppm or less.

In order to keep the total content of heavy metal ions in the polyarylene sulfide resin to 20 ppm or less, the liquid contact parts of the reactor and the filtration device are made of 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
Some are composed of groups or SH groups. 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,
Stable by treating with acid or acid salt solution before pelletization
It is preferable to convert it into an SH group. The amount of SNa group can be measured by quantifying the sodium ion content in the resin removed by sufficiently washing the by-product salt with water, and in order to obtain a hue of Hunter whiteness of 40% or more after pelletization, It is desirable to keep the sodium content of 100ppm or less. The amount of sodium ions in PPS can be measured by a calibration curve method using an atomic absorption spectrophotometer after heating and burning the resin in a muffle furnace after diluting the resin with sulfuric acid ash.

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, a concentration of 300 ° C or higher is required for PPS melt molding, and low boiling point (low molecular weight) anti-coloring agents will not be effective unless they are decomposed or volatilized during melt molding and used in large amounts. Also, the types of anti-coloring agents that can be used are 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 anti-coloring agent used in the present invention, that is, DOPO exerts the effects of both a free radical chain inhibitor and a peroxide decomposing agent, has a heat resistance of 300 ° C. or higher, and a small amount provides a sufficient anti-coloring effect. It does not cause an unfavorable reaction such as a crosslinking reaction.

The resin composition of the present invention has high whiteness after pelletization,
In particular, in addition to blending DOPO, the amount of organic amide solvent in the resin is 1,000 ppm or less, and the amount of heavy metal ions is 20 ppm.
The Hunter whiteness after pelletization of the product controlled below and treated with an aqueous sodium dihydrogen phosphate solution is 40% or more.

The hue-stabilized polyarylene sulfide resin composition of the present invention can be molded into heat-resistant films, sheets, fibers, etc., as well as automobile parts, electric / electronic parts, mechanical parts by injection molding, rotational molding, etc. And the like.

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, the pellets were preheated at 325 ° C for 3 minutes under a nitrogen stream using a hot press, and further heated at 325 ° C for 1 minute. An amorphous sheet of about 2 mm obtained by pressing and shaping into a sheet and then rapidly cooling was used as a sample.

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

Into the titanium-lined autoclaves of Examples 1 to 3 and Comparative Examples 1 to 100, 12.77 kg of flake sodium sulfide (purity 61.63%), 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 (9.61 kg) was 30% by weight. The loss of hydrogen sulfide during the dehydration process was 0.60 mol% in terms of sodium sulfide. After dehydration, cool to 160 ℃ and p-dichlorobenzene 146.1
2 kg was dissolved in 10 kg of N-methyl-2-pyrrolidone and added, and pressurized to 1 kg / cm ² G with nitrogen gas.
The mixture was reacted at ℃ for 3 hours, further at 250 ℃ for 2 hours, cooled to 150 ℃, and filtered under pressure while hot using a 400 mesh wire net as a filter material.

40 kg of N-methyl-2-pyrrolidone was added to the obtained solid content, and the mixture was washed with stirring under a nitrogen stream at 150 ° C. for 30 minutes, and then filtered under pressure while hot. After the same washing and filtration operations were repeated twice, the solid content was transferred to the autoclave, 40 kg of N-methyl-2-pyrrolidone was added, the atmosphere was replaced with nitrogen, and the polymerization reaction was carried out at 240 ° C. for 4 hours. .

After cooling to 150 ° C., filtration was carried out, 40 kg of trichloroethylene was added to the solid content, and the mixture was washed with stirring at 80 ° C. for 30 minutes and then filtered under pressure while hot. Thereafter, the same washing and filtration operations were performed 3 times to remove the remaining N-methyl-2-pyrrolidone. After drying the obtained solid content under the conditions of 60 mmHg and 120 ° C., it was transferred to the autoclave, 40 kg of pure water and 0.8 kg of sodium dihydrogen phosphate dihydrate were added and washed with water at 150 ° C. for 1 hour, Filtered. Repeated washing with water until the salt was gone, and dried to obtain 10.3 kg of powdered PPS. The melt viscosity of this product is 4,370.
Poise.

Add a solution of a predetermined amount of DOPO dissolved in methanol to the above PPS as a coloring inhibitor, and after stirring well,
Dry to remove methanol. The quality and characteristics of the obtained PPS are shown in Table-1.

Example 4 54.45 g of 1,3,5-trichlorobenzene (p-
0.3 mol% based on dichlorobenzene),
And 10.3 kg of powdered PPS was obtained by the same method as in Example 1 except that N-methyl-2-pyrrolidone was not washed and the polymerization reaction was not performed after the reaction. The melt viscosity of this product was 2,350 poise.

A solution of a predetermined amount of DOPO dissolved in methanol as a coloring inhibitor was added to this PPS, and the mixture was stirred well and dried to remove methanol. The quality and substances of the obtained PPS are shown in Table-1.

Examples 5 and 6 6.1 kg of water was added to the reaction solution slurry obtained by the reaction in the same manner as in Example 1, and the temperature was raised to 250 ° C. under a nitrogen stream.
The reaction was carried out for 10 hours. After cooling to 150 ° C., the mixture was filtered, 40 kg of trichloroethylene was added to the solid content, and the mixture was washed with stirring at 80 ° C. for 30 minutes and then filtered under pressure while hot. Thereafter, the same washing and filtering operation was performed three times to remove the remaining N-methyl-2-pyrrolidone. Then, the same treatment as in Example 1 was performed to obtain powdered PPS10.
2 kg was obtained. The melt viscosity of this product was 1,700 poise.

A solution of a predetermined amount of DOPO dissolved in methanol was added to this PPS, and the mixture was stirred well and dried to remove methanol. Table 1 shows the quality and physical properties of the obtained PPS.

Comparative Examples 4 to 6 To the powdery PPS obtained in Example 1, a coloring inhibitor other than DOPO was added as a solution dissolved in acetone, and the mixture was stirred well and dried 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, DO as a coloring inhibitor
By blending PO, a resin with high hunter whiteness can be obtained. In particular, when the residual NMP amount, heavy metal ion amount and sodium ion amount are lower than the above-mentioned predetermined values, the Hunter whiteness is 40% or more. That is, the Hunter whiteness was 25% when DOPO was not added (Comparative Example 1), whereas it was 48% when DOPO was added at 0.5 PHR (Example 2). It can be seen that there is no increase in the melt viscosity during conversion.

2,6-di- as a colorant which has been widely used in the past
Hunter whiteness in the case of using tert-butyl-p-cresol and triphenylphosphite together (Comparative Example 6) was DO.
It can be seen that it is inferior to the case of using PO and that the melt viscosity when pelletized increases.

Claims (5)

(57) [Claims] 1. A polyarylene sulfide resin and 0.05 per 100 parts by weight of the polyarylene sulfide resin.
A resin composition comprising 5 parts by weight of 3,4,5,6-dibenzo-1,2-oxaphosphane-2-oxide. 2. The composition according to claim 1, wherein the polyarylene sulfide resin is a polyphenylene sulfide resin. 3. The polyarylene sulfide resin is polymerized by using an organic amide solvent as a polymerization medium, and the content of the organic amide solvent in the resin is 1,000 ppm or less. ) The composition described. 4. The total content of heavy metal ions in the polyarylene sulfide resin is 20 ppm or less.
~ The composition according to any one of (3). 5. The polyarylene sulfide resin according to claim 1, wherein the polyarylene sulfide resin is treated at a temperature of 50 to 200 ° C. with an aqueous solution of at least one kind of phosphate salt, the aqueous solution of which is acidic. The composition according to any of the above.