JP2612302B2 - Method for producing crystal structure of syndiotactic polystyrene - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a syndiotactic polystyrene crystal structure having high crystallinity or crystal perfection, large crystallite size, and crystal structure having thermal stability. The present invention relates to a method for producing an α crystal.

[Prior art and problems] Syndiotactic polystyrene polymers are known to use a condensation product of (A) a titanium compound and (B) an organoaluminum compound with water as a catalyst component in the polymerization of styrene. This is described in JP-A-62-104818 and JP-A-62-187708. FIG. 1 shows an X-ray diffraction chart of the syndiotactic polystyrene exemplified in FIG. 2 (a) of JP-A-62-187708. According to the X-ray chart, known syndiotactic polystyrene has scattering angles of 6.9 degrees, 11.9 degrees, 15.6 degrees, and 18.0 degrees.
Degrees, 20.5 degrees can be read as having a diffraction peak,
It is understood that the crystal structure has the same crystal structure as the α-crystal of the present invention. Syndiotactic polystyrene having a similar crystal structure is described in Macromolecules 19,2465-2466.
(1986). A method for producing a β-crystal of a syndiotactic polystyrene crystal structure is described in JP-A-1-215808.

FIG. 2 is an X-ray diffraction pattern of powdery syndiotactic polystyrene as synthesized by the present inventors in accordance with the disclosure of JP-A-62-187708. FIG. 3 is an X-ray diffraction pattern of a structure obtained by melting powdery syndiotactic polystyrene as-synthesized according to the publication and then rapidly contacting (quench) with liquid nitrogen from this state. . This method is a method usually performed as a method for obtaining an amorphous substance of a polymer. Accordingly, FIG. 3 shows the X-ray diffraction pattern of the amorphous form of syndiotactic polystyrene.

By applying the analysis method of the crystal part and the amorphous part known from isotactic polystyrene (J. Appl. Phys., 37, 4003 (1966)) to the diffraction pattern in Fig. 2, the powder as synthesized Syndiotactic polystyrene is a polymer with a large proportion of amorphous parts. That is,
The diffraction pattern shown in FIG. 2 shows that it includes a region C of the diffraction pattern based on the crystal part above the broken line and a region A of the diffraction pattern based on the amorphous part below the broken line.
From the value of C / (A + C) × 100, it can be seen that the diffraction pattern is of a structure having very low crystallinity.

According to the inventor's findings, syndiotactic polystyrene further undergoes other crystal transformations under thermal processing conditions, as shown by the diffraction pattern in FIG. The second
Once the syndiotactic polystyrene in the figure is melted,
FIG. 3 is an X-ray diffraction pattern of a structure generated under the thermal processing conditions in Preparation Example 1 of β-crystal structure, which has a diffraction peak at a scattering angle of 6.1 degrees and no diffraction peak at a scattering angle of 15.6 degrees. X-ray diffraction pattern. Therefore, this crystal structure is disclosed in Japanese Patent Application Laid-Open No. 62-187708.
Unlike the crystal structure α-crystal of FIG.
It is a β crystal described in Japanese Patent Publication No. 08-08.

Similarly, FIG. 5 shows that the syndiotactic polystyrene of FIG.
5 is an X-ray diffraction pattern of a structure generated under the thermal processing conditions of FIG. Scattering angle 2θ = 6.2 generated in the range of 5.5 to 7.5 degrees
This is due to the presence of two diffraction peaks at 6.7 and 6.7 degrees.
It is a structure in which α crystals and β crystals are mixed.

[Problems to be Solved by the Invention] As described above, since there are various crystal structures, when molding syndiotactic polystyrene, use appropriate thermal processing conditions required for performance such as thermal stability. It is desired.

The present invention relates to a syndiotactic polystyrene crystal structure having a crystallinity equal to or higher than that of a crystal structure prepared by a known production method, and a crystal structure having a crystal structure having thermal stability. It relates to the manufacturing method.

[Means for Solving the Problems] In the structure containing the crystal structure β crystal of the syndiotactic polystyrene of the present invention, the temperature is at least 2 ° C. lower than the melting point of the β crystal under an atmosphere that does not cause decomposition of the structure. Then, heat is applied to the structure for at least 30 seconds to cause a phase transition of the syndiotactic polystyrene crystal structure into β and α crystals. is there.

 Hereinafter, the present invention will be described in detail.

The raw material of the structure of syndiotactic polystyrene is
For example, it is a syndiotactic polystyrene prepared by the polymerization method described in JP-A-62-187708. The polymer has a syndiotacticity and a number average molecular weight of 99%, 1.0 × 10 ⁴ or more, respectively. Those exhibiting at least useful mechanical properties in the body are selected.

Crystal structure of syndiotactic polystyrene The structure containing β crystal is as follows: (1) Isothermal crystallization of dissolved (melted) polymer in a temperature range of 240 to 270 ° C for 5 to 3000 hours in an atmosphere that does not cause polymer decomposition How to let.

(2) A method in which the dissolved (melted) polymer is cooled to 200 ° C or less at a cooling rate of 1.25 ° C / minute or less in an atmosphere in which the polymer does not decompose.

And the like. Such a preparation method is described in JP-A-1-215808.

Here, the β crystal refers to a syndiotactic polystyrene crystal structure satisfying the following conditions.

When CuKα rays (wavelength 0.15418 nm) are used as incident X-rays, X has a large characteristic that it has a diffraction peak roughly at a scattering angle 2θ = 6.1 degrees and no diffraction peak at a scattering angle 2θ = 15.6 degrees. A crystal structure giving a line diffraction pattern. Specifically, scattering angle 2θ = 11.8-13.0 degrees, 2θ = 1
2θ of the diffraction peak appearing at 8.1 to 19.3 degrees = 19.6 to 21.
The relative intensity to the diffraction peak that appears twice is 20%,
Has a diffraction peak of 5% or more, and 2θ = 5.5 to 6.6 degrees, 2
2θ = 19.6 ～ of the diffraction peak appearing at θ = 15.0-16.2 degrees
The relative intensity to the diffraction peak that appears at 21.2 degrees is 20
%, A crystal structure of syndiotactic polystyrene having a diffraction peak of less than 5%.

The α-crystal of syndiotactic polystyrene is
Refers to a syndiotactic polystyrene crystal structure satisfying the following conditions.

When a CuKα ray (wavelength: 0.15418 nm) is used as the incident X-ray, it is a crystal structure that gives an X-ray diffraction pattern having the characteristic of having diffraction peaks at scattering angles of 6.7 degrees and 15.6 degrees. Specifically, the scattering angle 2θ = 6.3 to 7.5 degrees, 2
Shinji having diffraction peaks of 18%, 8%, and 3% or more in relative intensity of the diffraction peaks appearing at θ = 11.0-13.0 degrees and 2θ = 14.8-16.2 degrees with respect to the diffraction peaks appearing at 2θ = 19.5-21.3 degrees, respectively. It is a crystal structure of tactic polystyrene.

In the above method, a crystal nucleus such as an inorganic substance is put into the raw material polymer by any method and crystallized, thereby increasing or decreasing the crystallization speed, shifting or expanding the crystallization temperature range, It is also possible to narrow it. For example, if the catalyst is left for several hundred ppm, the crystallization temperature during cooling is higher by 2 to 10 ° C. and the melting point of the structure is lower by 1 to 5 ° C. than when the catalyst is several tens ppm.

Measuring Method and Identification Method In the present invention, a method for measuring physical property values of syndiotactic polystyrene and a method for identifying a structure are as follows.

1) Measurement of stereoregularity and number average molecular weight Stereoregularity was determined from the C1 carbon spectrum of the benzene ring in a ¹³ C-NMR spectrum (nuclear magnetic resonance spectrum using isotope carbon) according to Nakromol. Chem., 176, 3051 (1975). The number average molecular weight was determined by gel permeation chromatography (measured in 1,2,4-trichlorobenzene at 130 ° C.).

2) Measurement of melting point of crystal structure The melting point of the crystal structure was determined from the peak of a chart obtained when a sample was heated at a constant rate (10 ° C./min) using a differential scanning calorimeter (abbreviated as DSC). The measurement conditions at that time were set as follows.

Apparatus: Perkin Elmer: DSC-2C Measurement atmosphere: Nitrogen atmosphere (under a flow rate of 22 cc / min) Temperature rise rate at the time of melting chart measurement: 10 ° C / min Refrigerant of the apparatus: ice water The horizontal axis indicates temperature [° C.] and the vertical axis indicates endothermic amount per unit time [mcal / sec].

3) Crystal structure identification method The X-ray diffraction method commonly used for crystal structure analysis is used to identify the crystal structure.

2 to 5 and 7 show CuK as incident X-rays.
5 is an X-ray diffraction pattern of a non-oriented syndiotactic polystyrene structure when α rays (wavelength: 0.15418 nm) are used. The number of headache indicates the diffraction peak of the corresponding number, and the broken line indicates how to set the baseline (FIG. 2 shows how to set the boundary between the amorphous part and the crystalline part). The horizontal axis is the scattering angle (θ is the Bragg kernel [核]), and the vertical axis is the scattering angle.

FIG. 7 is a representative X-ray diffraction pattern of the α-crystal of the syndiotactic polystyrene crystal structure of the present invention.
(Example of manufacturing crystalline structure α-crystal). This structure has a scattering angle of 2θ
= 6.6 degrees, 2θ = 11.6 degrees, 2θ = 15.5 degrees, 2θ = 17.9 degrees, 2θ = 2
Diffraction peak 1, peak 2, peak 3, peak 4, peak 0, and peak 5 are observed at 0.3 degrees and 2θ = 35.3 degrees, and they have the characteristic that they have diffraction peaks at scattering angles of 6.6 degrees and 15.5 degrees, respectively ( X-ray diffraction pattern of crystal structure β crystal).

Reading the diffraction intensity a. As shown in FIG. 7, the tangent line connecting peak 4 (when peak 4 is difficult to see, use peak 0) and valley f formed by peak 3 and valley i formed by peak 0 and peak 5 When the baseline fi is set, the intensity of the diffraction peak 0 at a scattering angle 2θ = 19.5 to 21.3 degrees from the baseline fi is defined as I ₀ .

b. Connect Figure 7, when both sides of the foot a peak 1, the tangent line connecting the b is the baseline ab, peak 1, the intensity from baseline ab and I _1.

c. As shown in FIG. 7, when both sides of the skirt c Peak 2, the tangent connecting the d and baseline cd, peak 2, the intensity from baseline cd and I _2.

d. As shown in FIG. 7, when both sides of the skirt e peaks 3, a tangential connecting f and baseline ef, peak 3, the intensity from baseline ef and I _3.

e. As shown in FIG. 7, when the tangent connecting the tails g and h on both sides of the peak 4 is defined as the baseline gh, the intensity of the peak 4 from the baseline gh is defined as I ₄ .

Note the following about each peak. When the crystal structure β crystal is included, the following tendency is observed in each peak. Peak 1 may have a low-angle skirt and peak 2 may have a high-angle skirt with shoulders or smaller peaks than the corresponding peaks 1 and 2, respectively. At this time, the baseline is set as follows: the shoulder or a peak smaller than the corresponding peaks 1 and 2;
Then, the base line is set with c as the valley immediately adjacent to the position exceeding the high angle side. When the peak 4 contains a β crystal, the peak 4 may have a large peak on the high angle side.

As the ratio of β crystals increases, peak 1 has a diffraction peak at each scattering 2θ = 6.0 to 6.3 degrees, and the diffraction intensity of peak 3 decreases, making it difficult to obtain the baseline ef. . When the peak 3 cannot be distinguished from noise, the intensity of the peak 3 is 0 and the point f of the baseline fi is e.
Points will be used.

According to the calculation method of each peak intensity in the calculation of diffraction intensity, peak 1, peak 2,
The relative intensities R ₁ , R ₂ , R ₃ , and R ₄ of the peaks 3 and ₄ are obtained by the following equations.

R ₁ = I ₁ / I ₀ × 100 (%)… (1) R ₂ = I ₂ / I ₀ × 100 (%)… (2) R ₃ = I ₃ / I ₀ × 100 (%)… … (3) R ₄ = I ₄ / I ₀ × 100 (%)… (4) 4) Judgment of crystallinity and crystal structure stability As shown in FIG. 2, X-ray diffraction of polymer structure The pattern is separated into a region C of the diffraction pattern considered to be based on the crystal part and a region A of the diffraction pattern considered to be based on the amorphous part. At this time, the area ratio C / (A + C)
From the magnitude of the value of × 100, it is determined that the greater the value, the higher the crystallinity. When it is difficult to obtain the region A of the diffraction pattern of the amorphous part, the base of each diffraction peak is connected according to the usual simple method, and it is considered as the boundary line between the amorphous part and the crystal part. I do.

The crystal structural stability means which crystal structure is energetically stable when a plurality of crystal structures exist in the same substance. In the case of syndiotactic polystyrene, since the crystal phase transition occurs from β-crystal to α-crystal, the α-crystal is more stable in crystal structure than the β-crystal.

[Effect] Considering that the temperature of the resin is not necessarily controlled and is not uniformly cooled in injection molding or the like, it is considered that high crystallinity and a uniform crystal structure cannot be obtained. According to the production method of the present invention, a molded product of crystal structure α-crystal having high crystallinity and stable crystal structure can be easily obtained.

In addition, this manufacturing method is not only important in terms of the method for refining α-crystals when different structures are included, but is also expected to be applied to polymer solid-state sensors, etc. by utilizing this mechanism of phase transition. You.

EXAMPLES Hereinafter, specific examples of the method for producing the syndiotactic polystyrene crystal structure α-crystal of the present invention will be described with reference to examples.

(Preparation example of raw polymer) In a container purged with an inert gas, 600 ml of toluene and 120 mmol of methylaluminoxane (manufactured by Toyo Stouffer)
And 0.6 mmol of tetraethoxytitanium, and then 600 ml of styrene, followed by a polymerization reaction at 50 ° C. for 2 hours.
After completion of the reaction, the reaction was stopped with hydrochloric acid / methanol, and the produced polymer was separated by filtration and dried. The resulting polystyrene (hereinafter syndiotactic polystyrene A)
Was 92 g. The content of the methyl ethyl ketone insoluble portion of this polystyrene was 96%, and the stereoregularity of the insoluble portion was a syndiotactic structure of 99% or more as a result of 13C-NMR spectrum analysis. The residual catalyst concentration in the insoluble part was determined by plasma-induced emission spectrometry (ICP) using Ti II (+ 1-valent ion beam) with a wavelength of 336.121 nm, and the result was 13 ppm. The result was gel permeation chromatography. Chromatography (in 1,2,4-trichlorobenzene, 13
(Measured at 0 ° C.), the number average molecular weight Mn was 2.47 × 10 ⁴ . The X-ray diffraction pattern of the syndiotactic polystyrene A obtained here is shown in FIG.

Preparation Example 1 of Crystalline Structure β 1 mg of syndiotactic polystyrene A was dissolved at 290 ° C in a nitrogen atmosphere, and then cooled at a cooling rate of 0,0 in the same atmosphere.
It was cooled to 150 ° C. at a rate of 31 ° C./min to obtain a disc-shaped structure B having a thickness of 1 mm and a diameter of about 8 mm. The X-ray diffraction pattern of this structure is shown in FIG. Peak 1, peak 2, peak 3, peak 4, peak 0, and peak 5 have scattering angles 2θ of 6.1 degrees, 12.3 degrees, and 15.7, respectively.
Degrees, 18.5 degrees, 20.3 degrees, and 35.0 degrees, and the relative intensity of each peak had the following values. This shows that this structure is a structure β crystal different from the α crystal specified in the present invention. The melting point of this structure was 263.3 ° C, and the number average molecular weight Mn determined by gel permeation chromatography (measured in 1,2,4-trichlorobenzene at 130 ° C)
Was not substantially different from syndiotactic polystyrene A.

R ₁ = 14%, R ₂ = 35%, R ₃ = 1.4%, R ₄ = 11% The characteristics of the β-crystal and α-crystal on the X-ray diffraction pattern are as follows.

Preparation Example 2 of Crystalline Crystalline β Crystals 5 mg of syndiotactic polystyrene A was melted at 290 ° C under a nitrogen atmosphere, and then cooled at a cooling rate of 320 ° C / min.
After cooling to ℃, the temperature was maintained for 20 minutes for crystallization to obtain a structure B. The X-ray diffraction pattern of this structure B
Shown in the figure. Peak 3, Peak 4, and Peak 0 are scattering angles 2θ respectively
Appeared at 15.6, 18.6, and 20.4 degrees, and peak 1 was 6.2.
The peak 2 was divided into 11.7 degrees and 12.4 degrees. FIG. 6 shows a melting chart of this structure B by DSC. Two
It had melting peaks at 58 ° C and 266 ° C. From these facts, according to the findings of the present inventors, it is assumed that the structure B has a mixed structure of α-crystal and β-crystal.

Production Example of Crystalline Structure α Crystal Structure B Obtained According to Preparation Example 2 of Crystalline Structure β Crystal
In a nitrogen atmosphere, the temperature was raised to 264 ° C at a rate of 320 ° C / min., Kept at this temperature for 48 hours, then lowered to room temperature, thickness 1 mm, diameter about 8 m.
Thus, a disk-shaped structure C of m was obtained. The X-ray diffraction pattern of this structure is shown in FIG. Peak 1, peak 2, peak 3, and peak 0 have scattering angles 2θ of 6.6, 11.6, 15.5, and 20.3 degrees, respectively, and the relative intensity of each peak has the following value. This shows that this structure is the α crystal specified by the present invention. The melting point of this structure is 271.5 ° C, and the number average molecular weight Mn determined by gel permeation chromatography (measured in 1,2,4-trichlorobenzene at 130 ° C) is substantially different from that of syndiotactic polystyrene A. Did not.

R ₁ = 48%, R ₂ = 29%, R ₃ = 15%

[Brief description of the drawings]

FIG. 1 is a transcript of the X-ray diffraction pattern of syndiotactic polystyrene shown in FIG. 2 (a) of JP-A-62-187708. FIG. 2 is an X-ray diffraction pattern of syndiotactic polystyrene A synthesized according to the method for preparing a raw material syndiotactic polystyrene. FIG. 3 is an X-ray diffraction pattern of a structure obtained by once melting the raw material syndiotactic polystyrene A and rapidly bringing it into contact with liquid nitrogen from this state. FIG. 4 is an X-ray diffraction pattern of the X-ray structure of the structure obtained according to Preparation Example 1 of the crystal structure β crystal. FIG. 5 is an X-ray diffraction pattern of structure B obtained according to Preparation Example 2 of crystal structure β crystal. FIG. 6 is a DSC melting chart of structure B obtained according to Preparation Example 2 of crystal structure β crystal. FIG. 7 is an X-ray diffraction pattern of the structure C obtained according to the production example of the crystal structure α-crystal.

Claims (1)

(57) [Claims] 1. A crystal structure β crystal of syndiotactic polystyrene (CuKα ray (wavelength 0.15418 nm) as incident X-ray)
, The angle of confusion 2θ = 11.8-13.0 degrees, 2θ = 18.1
The relative intensity of the diffraction peaks appearing at ~ 19.3 degrees with respect to the diffraction peaks appearing at 2θ = 19.6-21.2 degrees is 20%, respectively.
Having a diffraction peak of 5% or more, and 2θ = 5.5 to 6.6 degrees,
2θ of the diffraction peak appearing at 15.0 to 16.2 degrees = 19.6 to 2
The relative intensity to the diffraction peak that appears at 1.2 degrees is 20 each.
% Of a crystal structure of a syndiotactic polystyrene having a diffraction peak of less than 5%) in an atmosphere that does not cause analysis of the structure, at a temperature not lower than the melting point of the β crystal by 2 ° C. or higher. Is applied to the crystal for at least 30 seconds, and using a crystal structure crystal α of syndiotactic polystyrene (CuKα ray (wavelength: 0.15418 nm) as incident X-ray, the angle of confusion 2θ = 6.3 to 7.5 degrees, 2θ = 11.0 to 13.0 degrees, 2
2θ of the diffraction peak appearing at θ = 14.8 to 16.2 degrees = 19.5 to
The relative intensity to the diffraction peak that appears at 21.3 degrees is
A syndiotactic polystyrene crystal structure having diffraction peaks of 18%, 8% and 3% or more).