JP2006037007A - Polyphenylene sulfide made to have higher melting point and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyphenylene sulfide (PPS) made to have a higher melting point with improved heat resistance and provide a method for efficiently producing the PPS. <P>SOLUTION: The PPS made to have the higher melting point and having >283°C melting point is produced by heat treating a polyphenylene sulfide in a nonoxidative atmosphere under a specific condition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high melting point polyphenylene sulfide (hereinafter sometimes abbreviated as high melting point PPS) and a method for producing the same. More specifically, the present invention relates to a high melting point PPS with improved heat resistance and a method for efficiently producing the high melting point PPS.

  Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) is excellent in heat resistance, mechanical properties, flame retardancy, chemical resistance, and the like, and has been widely used for injection molding and extrusion molding. In particular, the heat resistance of PPS has a high melting point of about 280 ° C., and is relatively inexpensive among resins having the same melting point. Therefore, the use development in a field requiring high heat resistance has been rapidly advanced in recent years. . As a typical method for further improving the heat resistance characteristic of this PPS, a copolymerization method such as polyphenylene sulfide ketone (for example, see Patent Document 1) is known. There is a problem that the manufacturing is complicated because it is used.

  On the other hand, PPS is known to be used after being subjected to heat treatment by molding or the like, and typically, a method of performing melt extrusion under reduced pressure using an extruder provided with a vent port (for example, Patent Document 2). For example). However, this Patent Document 2 does not describe the melt-kneading time, that is, the heat treatment time, or the melting point of what is obtained after the melt-kneading. Therefore, it was not a method capable of obtaining a high melting point PPS of 283 ° C. or higher.

Further, a document disclosing “linear PPS having a melting point of 285 ° C.” in an example is also known (for example, refer to Patent Document 3). In Patent Document 3 where the measurement conditions are not defined, the melting point of PPS cannot be discussed. Further, Patent Document 3 describes that heat treatment was performed at 310 ° C. for 40 minutes in a low oxygen concentration (5 vol%) state. It is recognized that the melting point of the resulting PPS hardly increases.
JP-A-6-25416 (page 2) JP-A-2-219624 (first page) JP 11-158280 A (page 6)

  The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue.

  Accordingly, an object of the present invention is to provide a high melting point PPS with improved heat resistance and a method for efficiently producing this high melting point PPS.

  In order to achieve the above object, according to the present invention, a DSC-7 manufactured by PerkinElmer Co., Ltd. is used, and a) the temperature is raised from room temperature to 340 ° C. C) cooling from 340 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./min), d) holding at 100 ° C. for 1 minute, e) temperature increase from 100 ° C. to 340 ° C. (temperature increase rate: 20 ° C./min), f) Hold at 340 ° C. for 1 minute, g) Cool continuously from 340 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./minute), and the melting point indicated by the peak temperature of the melting peak observed in the above e) is 283 A polyphenylene sulfide obtained by heat-treating a high-melting polyphenylene sulfide having a melting point higher than 0 ° C. and polyphenylene sulfide under a non-oxidizing atmosphere under a condition satisfying the following formula (1): Use a) Room temperature ~ Temperature rise to 40 ° C. (temperature increase rate: 20 ° C./min), b) hold at 340 ° C. for 1 minute, c) cooling from 340 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./min), d) 1 at 100 ° C. E) temperature rise from 100 ° C. to 340 ° C. (temperature increase rate: 20 ° C./min), f) hold at 340 ° C. for 1 minute, g) cooling from 340 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./min) ) Is continuously performed, and a high-melting polyphenylene sulfide having a melting point exceeding 283 ° C. indicated by the peak temperature of the melting peak observed in the above e) is provided.

  (Wherein T is a heat treatment temperature (° C.) and is a temperature in the range exceeding the melting point of polyphenylene sulfide and less than the decomposition temperature, preferably in the range of more than 300 ° C. and less than 400 ° C., and t is a heat treatment temperature. Indicates time (minutes).)

  The method for producing the high melting point PPS of the present invention is characterized in that the melting point of polyphenylene sulfide is increased by heat-treating polyphenylene sulfide in a non-oxidizing atmosphere under the condition satisfying the following formula (1). To do.

  (Wherein T is a heat treatment temperature (° C.) and is a temperature in the range exceeding the melting point of polyphenylene sulfide and less than the decomposition temperature, preferably in the range of more than 300 ° C. and less than 400 ° C., and t is a heat treatment temperature. Indicates time (minutes).)

  According to the present invention, as described below, a high melting point PPS with improved heat resistance can be efficiently produced.

  The structural formula of PPS in the present invention has a repeating unit of-(phenylene group -S)-as a main structural unit. A polymer containing 80 mol% or more of the repeating unit is preferred. The phenylene group includes units represented by-(paraphenylene group-S)-,-(metaphenylene group-S)-, and-(orthophenylene group-S)-. The phenylene group is hydrogen, an alkyl group, or an alkoxy group. , A phenylene group composed of hydrogen as a substituent. Of these,-(paraphenylene group -S)-represented by the formula (A) is particularly preferable, and the structural unit is preferably contained in an amount of 80 mol% or more, particularly preferably 90 mol% or more.

  As long as this repeating unit is a main constituent unit, it can contain a small amount of branching units or crosslinking units.

  Further, the PPS in the present invention may be any of a random copolymer, a block copolymer and a mixture thereof containing the above repeating unit.

  Furthermore, although there are no particular limitations on the molecular weight of various PPSs, a preferred range is usually a melt viscosity of 5 to 5,000 Pa · s (300 ° C., shear rate 200 / sec). Within such a range of melt viscosity, for example, PPS obtained using an appropriate amount of a crosslinking agent such as trihalogenated benzene at the time of polymerization, or PPS formed with a crosslinked structure by heat treatment is acceptable.

  In the present invention, the production method of PPS is not particularly limited, but examples thereof include those obtained by polymerizing a polyhalogen aromatic compound and an alkali metal sulfide in a polar organic solvent under high temperature and high pressure. Since the obtained polymer contains a solvent and the like, a step of recovering PPS from the polymer is necessary. The recovery method is not particularly limited. For example, solid PPS is recovered by slowly cooling the polymer after the reaction, and filtering off and removing low molecular weight components and polymerization solvent contained in the obtained product. Examples thereof include a method and a method in which a polymer is discharged from a high temperature and high pressure state to an atmosphere of normal pressure or reduced pressure, and the polymerization solvent is recovered and at the same time, solid PPS is recovered.

  The melting point in the present invention is a temperature at which PPS in a solid phase under a constant pressure maintains an equilibrium with a liquid phase, and is also referred to as a melting point. The melting point in the present invention is a differential scanning calorimeter (hereinafter sometimes abbreviated as DSC), and the measurement is a) temperature rising from room temperature to 340 ° C. (temperature rising rate: 20 ° C./min), b) 340 ° C. C) Cooling from 340 ° C. to 100 ° C. (Temperature drop rate: 20 ° C./min), d) Holding at 100 ° C. for 1 min, e) Temperature rise from 100 ° C. to 340 ° C. (Temperature rise rate: 20 ° C.) F) Hold for 1 minute at 340 ° C., g) Perform a temperature program of cooling from 340 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./min), and at the peak temperature of the melting peak observed in e) above is there.

  The high melting point PPS of the present invention has a melting point measured by the above method of over 283 ° C., and has a much improved heat resistance as compared with the conventional PPS.

  The high melting point PPS of the present invention is produced by increasing the melting point of PPS by heat-treating PPS at a specific heat treatment temperature for a specific time in a non-oxidizing atmosphere. The atmosphere, heat treatment temperature, heat treatment time, and high melting point PPS will be described below.

[Non-oxidizing atmosphere]
The non-oxidizing atmosphere in the present invention means that the oxygen concentration is less than 1.0% by volume. As a method for producing the non-oxidizing atmosphere, an inert gas such as helium, argon, nitrogen or the like is used. The method to be used can be exemplified. These gases may be used alone or in combination of two or more. From the economical viewpoint, it is preferable to perform pressure reduction or use nitrogen. When heat treatment is performed at a temperature exceeding the melting point in an oxidizing atmosphere, the melting point tends to decrease due to the progress of the cross-linking reaction between PPS molecules in a short time heat treatment, and insolubility and infusibility are likely to occur in a long time heat treatment. Therefore, it is not preferable.

[Heat treatment temperature and heat treatment time]
In the present invention, the heat treatment time for sufficiently increasing the melting point of PPS varies depending on the heat treatment temperature, and it has been found from experimental data that it is necessary to perform heat treatment under conditions satisfying the following formula (1). Similarly, it has been found from experimental data that a heat treatment condition satisfying the formula (2) is preferable. In the range of formula (3), it is difficult to raise the melting point above 283 ° C., and in the range of formula (4), the decomposition reaction proceeds and the melting point tends to decrease.

  (However, T in the formula is a heat treatment temperature (° C.), which is a temperature in the range exceeding the melting point of polyphenylene sulfide and less than the decomposition temperature, and t represents a heat treatment time (minute).)

  When obtaining a high melting point PPS by the heat treatment method in the present invention, the heat treatment temperature needs to be a temperature exceeding the melting point as described above, but is preferably a temperature exceeding 300 ° C. and less than 400 ° C., The temperature is more preferably in the range of more than 300 ° C. and less than 370 ° C. When PPS is heat-treated in a non-oxidizing atmosphere below the melting point, the melting point after the heat treatment is almost the same as the melting point before the heat treatment, and no increase in the melting point is observed. Further, heat treatment at 400 ° C. or higher is not preferable because the decomposition reaction of PPS proceeds and the melting point tends to decrease.

[High melting point PPS]
The PPS before heat treatment is a highly heat-resistant crystalline resin having a melting point of usually around 280 ° C. However, when this PPS is subjected to heat treatment as described above, a resin having a melting point exceeding 283 ° C. is obtained. By performing the heat treatment under preferable conditions, a PPS having a melting point exceeding 285 ° C. after the heat treatment can be obtained. Thus, what was obtained is the high melting point PPS of the present invention. Examples of the heat treatment method for obtaining the high melting point PPS include a method of standing still and a method of melt extrusion.

  Further, the high melting point PPS after the heat treatment tends to have a higher melt crystallization temperature observed by DSC measurement than the PPS before the heat treatment, and the time required for crystallization when the heat treatment of the present invention is performed during the molding process. It also has the feature that it can lead to improved production efficiency than before, such as shortening and shortening the molding time.

  Hereinafter, the present invention will be described more specifically with reference to examples. The melting point was measured by the following method.

  [Measurement of Melting Point] PPS and a high melting point PPS obtained by heat-treating this resin at a temperature equal to or higher than the melting point were used as measurement samples. The measurement uses DSC-7 manufactured by PerkinElmer Co., Ltd. a) Temperature rise from room temperature to 340 ° C. (temperature rise rate: 20 ° C./min), b) hold at 340 ° C. for 1 minute, c) from 340 ° C. to 100 ° C. Cooling (temperature decrease rate: 20 ° C./min), d) holding at 100 ° C. for 1 minute, e) raising the temperature from 100 ° C. to 340 ° C. (heating rate: 20 ° C./min), f) holding at 340 ° C. for 1 minute, g) Cooling was continuously performed from 340 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./min), and the peak temperature of the melting peak observed in the above e) was defined as the melting point. Further, the peak of the melt crystallization peak observed in the above c) was taken as the melt crystallization temperature. The measurement sample was about 10 mg and was measured under a nitrogen atmosphere.

[Example 1]
Toraya M2888 (melt viscosity 50 Pa · s (300 ° C., shear rate 200 / sec)) manufactured by Toray Industries, Inc. was used as the PPS. 3 g of this PPS is weighed out, put in a vacuum dryer, reduced in pressure until the pressure in the vacuum dryer reaches 100 Pa (0.02 vol% in terms of oxygen concentration), and then heat treated at 320 ° C. for 120 minutes. It was. After heat treatment, the product was allowed to cool to room temperature and subjected to DSC measurement. The measurement results are shown in Table 1.

[Example 2]
Table 1 also shows the DSC measurement results of the PPS heat-treated in the same manner as in Example 1 except that the heat treatment was performed at 305 ° C. for 375 minutes.

[Example 3]
Table 1 also shows the DSC measurement results of the PPS heat-treated in the same manner as in Example 1 except that the heat treatment was performed at 350 ° C. for 20 minutes.

[Comparative Example 1]
Table 1 also shows the measurement results obtained by subjecting the PPS used in Example 1 to DSC measurement without heat treatment.

[Comparative Example 2]
Table 1 also shows the DSC measurement results of the PPS heat-treated in the same manner as in Example 1 except that the heat treatment was performed at 275 ° C. for 120 minutes.

[Comparative Example 3]
Table 1 also shows the DSC measurement results of the PPS heat-treated in the same manner as in Example 1 except that the heat treatment was performed at 320 ° C. for 30 minutes.

[Comparative Example 4]
Table 1 also shows the DSC measurement results of the PPS heat-treated in the same manner as in Example 1 except that the heat treatment was performed at 350 ° C. for 120 minutes.

[Comparative Example 5]
Table 1 also shows the DSC measurement results of the PPS heat-treated in the same manner as in Example 1 except that the heat treatment was performed in the air.

  Moreover, the graph showing the relationship of the heat processing time with respect to the heat processing temperature in Examples 1-3 and Comparative Examples 3-4 is shown in FIG.

1): Melt peak cannot be observed 2): Melt crystallization peak cannot be observed

  As is apparent from the results of Table 1 and FIG. 1, in Example 1, the heat treatment was performed under particularly preferable conditions, and the melting point was improved by over 285 ° C. compared with Comparative Example 1 in which heat treatment was not performed. Recognize. Moreover, it turns out that melting | fusing point improves in Example 2 and Example 3 which heat-processed on preferable conditions exceeding 283 degreeC. On the other hand, in Comparative Example 2 in which heat treatment was performed at a temperature lower than the melting point, and in Comparative Example 3 and Comparative Example 4 in which heat treatment was performed outside the condition range of the formula (1), the melting point was about the same or slightly increased as compared with Example 1. It turns out that it is a grade to do. Moreover, since the melting peak and the melt crystallization peak are not observed in Comparative Example 5 performed in an oxidizing atmosphere, it is understood that the conditions are not preferable for increasing the melting point.

  According to the present invention, a high melting point polyphenylene sulfide having improved heat resistance can be produced efficiently and efficiently, and the resulting high melting point PPS can be widely used for injection molding and extrusion molding. Can do.

It is a graph showing the relationship of the heat processing time with respect to the heat processing temperature in Examples 1-3 and Comparative Examples 3-4.

Claims (5)

Using DSC-7 manufactured by PerkinElmer, Inc.) a) Temperature rising from room temperature to 340 ° C. (temperature rising rate: 20 ° C./min), b) holding at 340 ° C. for 1 minute, c) cooling from 340 ° C. to 100 ° C. (temperature decreasing) D) held at 100 ° C. for 1 minute, e) heated from 100 ° C. to 340 ° C. (temperature rising rate: 20 ° C./minute), f) held at 340 ° C. for 1 minute, g) 340 A high-melting polyphenylene sulfide having a melting point exceeding 283 ° C., which is continuously cooled from 100 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./min) and indicated by the peak of the melting peak observed in e). Polyphenylene sulfide obtained by heat-treating polyphenylene sulfide in a non-oxidizing atmosphere under conditions satisfying the following formula (1), using DSC-7 manufactured by Perkin Elmer, Inc., a) rising from room temperature to 340 ° C Temperature (temperature increase rate: 20 ° C./min), b) hold at 340 ° C. for 1 minute, c) cool from 340 ° C. to 100 ° C. (temperature decrease rate: 20 ° C./min), d) hold at 100 ° C. for 1 minute, e ) Temperature rise from 100 ° C. to 340 ° C. (temperature rise rate: 20 ° C./min), f) hold at 340 ° C. for 1 minute, g) cooling from 340 ° C. to 100 ° C. (temperature drop rate: 20 ° C./min) continuously A high-melting polyphenylene sulfide having a melting point of 283 ° C. exceeding the melting peak observed in e).

(However, T in the formula is the heat treatment temperature (° C.), which is a temperature in the range of exceeding the melting point of polyphenylene sulfide and less than the decomposition temperature, and t is the heat treatment time (minutes).) The high-melting polyphenylene sulfide according to claim 2, wherein the heat treatment temperature T is in the range of more than 300 ° C and less than 400 ° C. The high melting point according to any one of claims 1 to 3, wherein the polyphenylene sulfide is heat-treated in a non-oxidizing atmosphere under a condition satisfying the following formula (1) to raise the melting point of the polyphenylene sulfide. A method for producing polyphenylene sulfide.

(However, T in the formula is a heat treatment temperature (° C.), a temperature in the range exceeding the melting point of polyphenylene sulfide and less than the decomposition temperature, and t represents a heat treatment time (minute).) The method for producing a high-melting polyphenylene sulfide according to claim 4, wherein the heat treatment temperature T is a temperature in the range of more than 300 ° C and less than 400 ° C.

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