JP3895150B2 - Polyester resin molded product - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a blend molded article of polyethylene terephthalate (PET) and polytrimethylene terephthalate (PTT).
[0002]
[Prior art and problems to be solved by the invention]
PET is widely used in bottles, films, fibers and the like because of its excellent mechanical properties such as heat resistance and impact resistance, as well as transparency and chemical resistance. However, PET has the disadvantage that its crystallization rate is very slow and inferior in moldability. For PET injection-molded products, improvement of moldability is currently achieved by adding crystal nucleating agents and plasticizers, and adding glass fibers. ing.
[0003]
On the other hand, various researches have been conducted on polymer blends that blend two or more types of thermoplastic resins to develop the advantages of each resin, and a variety of blends of thermoplastic resins have also been proposed for PET. In particular, blends with other polyesters having good compatibility are expected to produce good results. For example, for the purpose of further increasing the strength and improving the heat resistance, a technique of blending polybutylene terephthalate (PBT) or polyethylene naphthalate (PEN) with PET has been performed.
[0004]
However, these methods can achieve high strength and heat resistance to some extent, but they do not lead to acceleration of the crystallization speed and are still insufficient in terms of moldability.
[0005]
[Means for Solving the Problems]
As a result of intensive studies in view of the above-mentioned problems of the prior art, the present inventors have found that a molded product obtained by blending PTT with PET under specific conditions has a significantly increased crystallization speed and is excellent in molding processability. As a result, the present invention has been completed.
[0006]
That is, the present invention prepares a molten mixture by melt-kneading polyethylene terephthalate and polytrimethylene terephthalate at a temperature 50 to 80 ° C. higher than the melting point of polyethylene terephthalate for 1 to 10 minutes, and then 0 to 250 to 300 ° C. A polyester resin molded product formed by molding for 1 to 5 minutes.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below. First, the polyethylene terephthalate (PET) used in the present invention is a polyester obtained by polycondensation of terephthalic acid or an ester-forming derivative thereof and ethylene glycol or an ester-forming derivative thereof, and is a known comonomer such as isophthalic acid. A copolymer introduced in a small amount may be used.
[0008]
The polytrimethylene terephthalate (PTT) used in the present invention is a polyester obtained by polycondensation of terephthalic acid or an ester-forming derivative thereof and 1,3-propanediol or an ester-forming derivative thereof. A copolymer in which a small amount of a known comonomer such as the above is introduced may also be used.
[0009]
Compared to PET and PBT derived from ethylene glycol or 1,4-butanediol having an even number of methylene groups in the glycol chain, PTT is derived from 1,3-propanediol having an odd number of methylene groups. Crystallization and rheological behavior are considered to be unique and attract attention as a polymer having the advantages of PET and PBT.
[0010]
The feature of the present invention is that PTT is blended with PET, both are melt-kneaded at a temperature 50 to 80 ° C. higher than the melting point of PET for 1 to 10 minutes, and then molded at 250 to 300 ° C. for 0.1 to 5 minutes. there to that point to.
[0011]
Here, in a general polymer blend, melt kneading is usually performed at a temperature near or slightly higher than the melting point of the higher polymer of the two polymers to be blended. If the above method is applied to a blend system of PET (melting point around 250 ° C.) and PTT (melting point around 225 ° C.) and melt-kneaded at a temperature near or slightly higher than the melting point of PET, the expected effect of the present invention is not exhibited, the effect of increasing the crystallization rate is not kneaded at 5 0 to 80 ° C. higher temperatures Ri by the melting point of the PET can not be obtained. Here, the melt kneading time is preferably about 1 to 10 minutes.
[0012]
In the present invention, after the melt-kneading the PET and PTT, 0.1 to 5 minutes at a temperature range of 250 to 300 ° C., preferably molded under factory over 0.5 to 3 minutes, expressing a phase separation structure It is necessary to make it. The target temperature for the heat treatment is in the range of 250 ° C. or higher, which is the melting point temperature (Tm) of the blend of PET and PTT, and 300 ° C. or lower, which is near the phase separation temperature of PET and PTT. In such a temperature, if you molded over 0.1-5 minutes, and miniaturization spherulite size, crystallization rate increases significantly.
[0013]
That is, in the case of a blend of PET and PTT, they are compatible at the high melting temperature, and liquid-liquid phase separation occurs below that temperature. Therefore, a UCST (upper critical solution temperature) type phase is used. It is considered to have a figure. Moreover, when the blend is cooled and isothermally crystallized as described above, fine spherulites of about 2 μm are obtained. As a result, as is apparent from the results of the change over time in the integrated intensity Q during isothermal crystallization in FIG. 1 which is data of Example 1 and Comparative Examples 1 and 2 described later, in the case of PET alone and PTT alone, crystallization occurs. It takes about 27 seconds and 28 seconds to complete, respectively, whereas for a 50/50 blend, crystallization is completed in as little as 5 seconds.
[0014]
Here, the crystallization rate is represented by the product of the line growth rate and the crystal nucleation frequency, but the line growth rate of the blend was not faster than that of the single PTT, so the crystallization rate in the blend was This increase is thought to be mainly due to the increase in the frequency of crystal nucleation. In the present invention, spinodal decomposition proceeds and concentration fluctuations increase due to the temperature drop from the melt kneading at the high temperature to the vicinity of the phase separation temperature, and crystal nucleus formation is induced by the accompanying up-hill-diffusion to cause crystallization. Can be assumed to be accelerated.
[0015]
In the present invention, the blend ratio of PET and PTT is generally preferably about 20 to 80% by weight of PTT in the total of both. If it is out of this range, it becomes a composition close to a homopolymer, and a sufficient crystallization speed acceleration effect cannot be obtained.
[0016]
The method for kneading the molten mixture of the present invention is not particularly limited as long as it is carried out by an extruder, an extruder, a mixer or the like, but it is preferably carried out by a uniaxial or biaxial extruder. Also, the method of heat treatment after melt-kneading is not particularly limited, but the method is a method in which the mixture is immediately cooled to a temperature of 250 to 300 ° C. and held for 0.1 to 5 minutes, or after melt-kneading and without undergoing heat treatment. A method such as cooling, obtaining a normal molten mixture, and holding at 250 to 300 ° C. for 0.1 to 5 minutes before the next molding can be considered.
[0017]
In the present invention, the molten mixture phase-separated or phase-separated at the same time as molding as described above is molded at a general molding temperature of PET of 260 to 320 ° C. to form bottles, films and fibers. It can be set as various molded products such as. The resin molded product of the present invention includes various fillers such as glass fiber and various minerals, various polymer modifiers, antioxidants, flame retardants, etc. Can be used.
[0018]
The molding method of the composition of the present invention is not particularly limited, such as injection molding, extrusion molding, blow molding and the like, but injection molding is particularly preferable.
[0019]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these.
Example 1
50 parts by weight of polyethylene terephthalate (PET; Wintech Polymer, melting point 250 ° C., weight average molecular weight 60000) and 50 parts by weight of polytrimethylene terephthalate (PTT; melting point 225 ° C., melt flow index 60 g / 10 min. 250 ° C.) The mixture was kneaded at 300 ° C. for 5 minutes using a small kneading machine (manufactured by CSI, Minimax mixing extruder) to obtain a transparent and uniform mixed melt. This mixed melt was rolled for 1 minute with a hot press machine (manufactured by Imoto Seisakusho) having a copper plate maintained at 270 ° C. Then, it cooled to room temperature and took out the kneaded material used as the thin film form.
[0020]
This film was subjected to isothermal crystallization process at 180 ° C. by a vertical light scattering measuring device (manufactured by Princeton, TE / CCD-512-TMK / 1), and a scattered light component (due to optical anisotropy of the film) Observation using (Hv scattering) gave the light scattering integrated intensity time evolution curve shown in FIG. The crystallization time defined when the light scattering integrated intensity was saturated was 5 seconds.
[0021]
When the crystallized film was observed with a polarizing microscope (Olympus, BX50F4) under crossed Nicols, a state in which fine crystals were densely packed as shown in FIG. 2 was observed.
Comparative Example 1
A film was obtained in the same manner as in Example 1 except that 100 parts by weight of PET was used instead of the mixture of PET and PTT in Example 1, and crystallization was observed. In crystallization at 180 ° C., the crystallization time indicated by the light scattering integrated intensity was very long as 27 seconds as shown in FIG. Further, according to observation with a polarizing microscope under crossed Nicols, it was found that a large crystal structure called a spherulite was seen relatively coarsely as shown in FIG. 2, and a uniform and dense crystal structure was not obtained.
Comparative Example 2
A film was obtained in the same manner using 100 parts by weight of PTT instead of PET of Comparative Example 1, and crystallization was observed. In crystallization at 180 ° C., the crystallization time indicated by the light scattering integrated intensity is very long as 28 seconds as shown in FIG. 1, and the crystal structure by polarization microscope observation under crossed Nicols is as shown in FIG. It was uneven and rough.
Examples 2-3
A film was obtained in the same manner except that the ratio of PET and PTT in Example 1 was changed to 30 parts by weight / 70 parts by weight and 70 parts by weight / 30 parts by weight, respectively, and the crystallization time was measured. . FIG. 3 shows the crystallization time when the ratio of PET to PTT is 0/100, 30/70, 50/50, 70/30, 100/0. In any of the compositions 30/70 and 70/30, a remarkable effect of shortening the crystallization time was recognized as compared with the cases of PET alone and PTT alone.
Comparative Example 3
50 parts by weight of PET and 50 parts by weight of PTT were kneaded at 300 ° C. for 5 minutes using the small kneading machine of Example 1 to obtain a transparent and uniform mixed melt. This mixed melt was rolled for 1 minute with a hot press machine (manufactured by Imoto Seisakusho) having a copper plate maintained at 320 ° C. Then, it cooled to room temperature and took out the kneaded material used as the thin film form.
[0022]
With respect to this film, an isothermal crystallization process at 180 ° C. was observed using a vertical light scattering apparatus in the same manner as in Example 1. As a result, a light scattering integrated intensity time development curve shown in FIG. 4 was obtained. The crystallization time was evaluated from FIG. 4 and found to be 38 seconds. That is, it was confirmed that the crystallization time was remarkably slow compared with 5 seconds when rolling at 270 ° C.
[Brief description of the drawings]
FIG. 1 is a graph showing the results of changes over time in integrated intensity Q during isothermal crystallization for films obtained from PET alone, PTT alone and a PET / PTT (50/50) blend.
FIG. 2 is a diagram obtained by observing the crystallized film obtained in Example 1 and Comparative Examples 1 and 2 with a polarizing microscope, (a) PET alone, (c) PTT alone, (b) PET / PTT (50/50).
FIG. 3 is a graph showing the composition dependency of the crystallization time of PET / PTT.
FIG. 4 is a graph showing the results of changes over time in the light scattering integral intensity Q depending on the difference in heat treatment temperature (Ta) of a PET / PTT (50/50) blend.

Claims (1)

A melt mixture is prepared by melting and kneading polyethylene terephthalate and polytrimethylene terephthalate at a temperature 50 to 80 ° C. higher than the melting point of polyethylene terephthalate for 1 to 10 minutes, and then at 250 to 300 ° C. for 0.1 to 5 minutes. Polyester resin molded product formed by molding.

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