JP3395903B2 - Transparent flexible polyester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent flexible polyester which is excellent in transparency, flexibility and handleability and can be used for forming a molded article such as a sheet, a film, an engineering plastic, a tube, a packaging bag, a skin, a stationery. Regarding

BACKGROUND ART Conventionally, as a transparent and flexible molded article, for example, a sheet,
Polyvinyl chloride resins (hereinafter abbreviated as polyvinyl chloride) have been widely used for applications such as films, tubes, and infusion bags.

However, vinyl chloride is added with a large amount of a phthalate ester-based plasticizer for the purpose of imparting flexibility. Moreover, it has been pointed out that PVC products generate carcinogenic dioxin when incinerated, which tends to be avoided from the environmental and hygiene viewpoints.

On the other hand, polyester resins represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and poly-1,4-cyclohexanedimethylene terephthalate (PCT) have environmental and hygiene problems. It is widely used for fibers, films, engineering plastics, bottles, etc. because it has no physical properties and excellent physical and chemical properties.

However, all of them have drawbacks of lacking in flexibility and rubber elasticity at room temperature and being hard, so that there is a limit in expanding applications. Many methods have been disclosed for imparting flexibility by copolymerizing a polyester with a soft segment for the purpose of improving such drawbacks.

For example, Japanese Patent Publication 57-48577 and Japanese Patent Publication 54
No. 15913 discloses long-chain polyethers such as polytetramethylene glycol (PTMG) and long-chain aliphatic dicarboxylic acids such as dimer acid (DiA) in PBT.
There is disclosed a technique of imparting flexibility by copolymerizing with. However, these copolyesters,
Polybutylene terephthalate (PB
Since the crystalline phase of T) is used, there is a problem that the molded body is highly likely to be crystallized and the transparency is lowered due to whitening.

Representative examples of polyester elastomers include Perprene (Toyobo) and Hytrel (Toray DuPont). The polyester elastomer may be an ether type that uses polyalkylene oxide glycol (PTMG is a typical example), depending on the type of soft segment that imparts flexibility to the polyester.
There are two types of ester type using an aliphatic polyester (typically polycaprolactone). However, all of them utilize the crystal phase of PBT for the hard segment. The main reason why PBT is used in the hard segment is its crystallinity. The crystallinity of PBT is the highest among many polyesters, and it is possible to provide a polyester elastomer having excellent moldability, handleability, and productivity.

However, the crystallinity of this PBT is a great obstacle to imparting transparency to the polyester elastomer. Conventionally, a method of disturbing the crystal structure by copolymerizing an acid component other than terephthalic acid (TPA) with PBT for the purpose of improving transparency has been proposed. However, in this method, the Tg and the softening point are lowered and the adhesiveness is increased, so that there is a problem that the handling property is remarkably deteriorated, such as blocking during resin drying and deterioration of molding / workability. .

On the other hand, many attempts have been made to develop a polyester elastomer having polyethylene terephthalate (PET) as a hard segment. For example, JP-A-48-5523
Japanese Patent Publication No. 5 and Japanese Patent Publication No. 42709/1987 disclose a technique of imparting flexibility by copolymerizing PET with PTMG or DiA. However, these polyester copolymers give a transparent and flexible molded product immediately after molding, but when left at a temperature not lower than the glass transition point (Tg), crystallization progresses, and whitening reduces transparency. There's a problem.

Furthermore, when the amount of PTMG or DiA copolymerized is increased, Tg and the softening point are lowered and the adhesiveness is increased. Therefore, the mold releasability from the mold or roller at the time of molding becomes poor, or in the case of a sheet or the like, the sheets do not adhere to each other during winding, blocking occurs at the time of resin drying, etc. It causes a big problem in terms of handleability.

Japanese Unexamined Patent Publication No. 2-24419 and Japanese Unexamined Patent Publication No. 6-1283.
No. 63, US Pat. No. 4,451,641 discloses a technique for imparting flexibility by copolymerizing dimer diol (DDO) with a polyester composed of TPA and ethylene glycol (EG) or TMG. However, since the crystal phase of PBT is used for the hard segment, there is a problem that whitening occurs due to crystallization and transparency is reduced.

Further, Japanese Patent Publication No. 595142 discloses a resin composition obtained by adding a sodium salt of a carboxylic acid to a copolyester using polyalkylene oxide in a soft segment, and Japanese Patent Application Laid-Open No. 4-91123 discloses terephthalic acid and dimer acid ( A copolymerized polyester in which the composition ratio of DiA), ethylene glycol (EG) and butanediol (BD) is regulated is disclosed.

However, even the copolyesters obtained by these methods have whiteness due to crystallization in the unstretched state and have no transparency, and because they have adhesiveness, they have poor releasability from the mold or roller. In addition, the handling properties were insufficient, such as the occurrence of adhesion between the molded products.

That is, the present situation is that a transparent flexible polyester satisfying all of transparency, flexibility, and handling property has not been developed yet.

The present invention has been made in view of the above circumstances, and its object is transparency, flexibility, and handleability suitable for forming applications such as sheets, films, engineering plastics, tubes, packaging bags, skins, and stationery. To provide an excellent transparent flexible polyester.

DISCLOSURE OF THE INVENTION The first invention of the present invention is a transparent flexible polyester having a copolyester composed of a hard segment and a soft segment as a main constituent, and an unstretched sheet obtained by melt-molding the transparent flexible polyester. A transparent flexible polyester having an elastic modulus of 1500 MPa or less, a crystallization index Xc measured by wide-angle X-ray of 5% or more, and a haze (100 μm conversion) of 15% or less.

In the second invention, at least 70 mol% or more of the dicarboxylic acid component constituting the hard segment is terephthalic acid (TPA) or 2,6-naphthalenedicarboxylic acid (ND).
A), at least one selected from 4,4'-biphenyldicarboxylic acid (BPA)
The transparent flexible polyester according to the invention.

In the third invention, the glycol component constituting the hard segment is 1,4-tetramethylene glycol (TM
G) and ethylene glycol (EG), and the composition ratio to the total glycol component constituting the hard segment is 20 to 95 mol% for TMG and 5 to 8 for EG.
It is 0 mol%, It is a transparent flexible polyester as described in the 1st or 2nd invention characterized by the above-mentioned.

In a fourth aspect of the invention, the soft component constituting the soft segment is a long-chain aliphatic dicarboxylic acid having a number average molecular weight of 100 to 1,000 and a number average molecular weight of 100 to 1,000.
Long-chain aliphatic glycol having a number average molecular weight of 500 to
First, characterized in that it is at least one kind of polyalkylene oxide glycol which is 4,000,
3 is a transparent flexible polyester according to any one of the inventions of 3.

In a fifth aspect, the soft component constituting the soft segment is dimer diol (DDO), and the composition ratio of DDO to the total glycol component of the polyester is 1
It is a transparent flexible polyester in any one of the 1st, 2nd, and 3rd invention characterized by being -60 mol%.

In a sixth aspect of the invention, the transparent flexible polyester comprises a metal salt compound having a metal element of Group Ia or Group II-a of the Periodic Table as a metal element relative to polyester.
The transparent flexible polyester according to the first invention is characterized by containing 5 to 5.0% by weight.

The transparent flexible polyester of the present invention is a transparent flexible polyester mainly containing a copolymerized polyester composed of a hard segment and a soft segment. The purpose of introducing the hard segment into the polyester molecular chain is to impart blocking property and transparency to the polyester. On the other hand, the purpose of introducing the soft segment into the polyester molecular chain is to impart flexibility to the polyester.

The transparent flexible polyester of the present invention has an elastic modulus of 1 when melt-molded into a non-stretched sheet.
Since it is 500 MPa or less, it is excellent in flexibility.

Further, the transparent flexible polyester of the present invention has an excellent handling property because the crystallization index Xc measured by wide-angle X-ray is 5% or more. Furthermore, since the haze of the unstretched sheet obtained by melt-molding the transparent flexible polyester is 15% or less in terms of sheet thickness of 100 μm, it has excellent transparency.

Hereinafter, embodiments of the transparent flexible polyester of the present invention will be described in detail.

(Hard segment) In developing a transparent flexible polyester having all three properties of transparency, flexibility, and handling property, the most difficult technical problem is to balance transparency and handling property. For that purpose, it is important to design the hard segment that restrains the soft segment.

From the viewpoint of crystals, transparency and handling are tradeoffs. The reason for this is that as the crystallization progresses, the transparency deteriorates, but the handling property improves conversely. That is, how to balance the contradictory characteristics of transparency and handleability is the most important technical problem in the present invention.

Generally, when PET having a low crystallization rate is rapidly cooled from a molten state to a supercooled state (amorphous) at the time of molding,
A transparent molding is obtained. However, if the obtained molded product is left at a temperature of Tg or higher, crystallization progresses and whitening occurs. This phenomenon is a result of crystals growing as crystallization progresses. Therefore, in order to improve the transparency, it is necessary to make the size of the crystal as small as possible, that is, to make the crystal fine.

On the other hand, handleability, that is, blocking during resin drying, dissociation from molds and rollers during molding / processing, and adhesion between molded products, etc., is dependent on the degree of crystallization, in other words, irrespective of crystal size. Then it is dominated by the crystallinity. Crystallinity is defined as the product of the number of crystals and the crystal size.

From the above, when configuring the hard segment in the crystal phase, from the viewpoint of transparency, to make the size of the crystallites, and from the viewpoint of handling controlled by the degree of crystallinity, The two requirements of increasing the number are essential.

For that purpose, selection of the polymer structure constituting the hard segment is very important.

Generally, the crystallinity of polyester greatly differs depending on the polymer structure. For example, typical PET and PBT have significantly different crystallinities, and PBT has a very high crystallization rate. From the viewpoint of achieving both transparency and handling properties, the crystal phase is required to be fine crystals and large in number.

As a polyester composition that can satisfy these requirements, for example, by using a hard segment satisfying the following two conditions, a polyester having both transparency and handling property can be obtained.

(1) As a glycol component of polyester constituting the hard segment, 1,4-tetramethylene glycol (TMG) and ethylene glycol (EG) are contained, and the composition ratio of the polyester constituting the hard segment to all glycol components is TMG. Is 20-95 mol%
And EG is 5 to 80 mol%.

(2) Terephthalic acid (TPA), 2,6 as the dicarboxylic acid component of polyester constituting the hard segment
-Contain at least 70 mol% of at least one selected from naphthalenedicarboxylic acid (NDA) and 4,4'-biphenyldicarboxylic acid (BPA).

If the above two conditions are not satisfied, the crystals do not become fine crystals and whiten and lose transparency, or the softening point decreases and the adhesiveness increases, and the handling property during drying and molding of the resin deteriorates. Etc. loses practical value.

The composition of the polyester that constitutes the hard segment is
As the glycol component, TMG / EG is more preferably 23 to 94 mol% / 77 to 6 mol%, and particularly preferably TMG / EG is 25 to 93 mol% / 75 to 7
Mol%. On the other hand, as the dicarboxylic acid component, TP
At least one selected from A, NDA and BPA is 75
It is more preferably at least mol%, particularly preferably at least 80 mol%.

The polyester constituting the hard segment is, in addition to the dicarboxylic acid, diphthalic acid such as isophthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid and sebacic acid, and the glycol component is 1,3-trimethylene glycol, 1, 5-pentamethylene glycol, 1,4-cyclohexanedimethanol, 1,6-
It is also possible to use glycols such as hexamethylene dimethanol as a copolymerization component.

Furthermore, for microcrystallization, it is effective to use a metal salt compound in combination as a crystallization accelerator, which is more preferable from the viewpoint of transparency.

In particular, for the transparent flexible polyester of the present invention, a metal salt compound having a metal element belonging to Group Ia or Group II-a of the Periodic Table is preferable. Of these, Li, Na, K and Ca salts of aliphatic carboxylic acids or phosphorus compounds are preferable.

Although the content of the metal salt compound varies depending on the composition of the polyester, the content of the metal salt compound in the polyester is 0.
It is effective to contain 5 to 5.0% by weight. If the content of the metal salt compound with respect to the polyester is less than 0.5% by weight, the crystallization promoting effect is small, and conversely 5.0% by weight.
If it exceeds, not only the dispersibility in polyester is deteriorated, but also the moldability and the physical properties are remarkably deteriorated. The lower limit of the content of the metal salt compound is more preferably 0.8% by weight with respect to the polyester, and particularly preferably 1.0
% By weight. The upper limit of the content of the metal salt compound is more preferably 4.5% by weight, and particularly preferably 4.0% by weight, based on the polyester.

(Soft segment) The soft segment is essential for imparting flexibility to the polyester, and it is important to have entropy elasticity. Suitable soft ingredients include polyarylene oxide glycols, aliphatic polyesters, long chain aliphatic dicarboxylic acids, long chain aliphatic glycols and the like.

When a long-chain aliphatic dicarboxylic acid or a long-chain aliphatic glycol is used as the soft component, the number average molecular weight is 10
If it is less than 0, it is difficult to obtain sufficient flexibility. On the other hand, when the number average molecular weight exceeds 1,000, the compatibility with the hard segment deteriorates and the transparency tends to decrease. When polyalkylene oxide glycol is used, when the number average molecular weight range is less than 500 or more than 4,000, the intended transparent flexible polyester is not obtained.

In the present invention, as the soft component of the transparent flexible polyester, dimer diol (DDO), which is a long-chain aliphatic glycol, is most effective in terms of transparency. Although the composition ratio of DDO varies depending on the desired flexibility, it is preferably 1 to 60 mol%, more preferably 2 to 58 mol%, and particularly preferably 3 to 55 mol% with respect to the total glycol component of the polyester. is there. If the composition ratio of DDO is less than 1 mol%, the flexibility becomes insufficient and the composition becomes hard. On the other hand, 6
If it exceeds 0 mol%, the Tg tends to be too low, and the moldability / workability and handleability tend to deteriorate.

(Polymerization of Copolymerized Polyester) As a method of polymerizing the copolymerized polyester, a conventionally known method can be applied. For example, an aromatic dicarboxylic acid or a lower alkyl ester thereof and an diol such as ethylene glycol, propylene glycol, tetramethylene glycol, 1,4-cyclohexanedimethanol or dimer diol are esterified or transesterified to form a low molecular weight product. The most common method is to produce by an initial reaction that is generated and a late reaction that polycondenses the low molecular weight product to a high molecular weight.

For the production of copolymerized polyester, as a transesterification catalyst, conventionally known titanium, zinc, manganese, cobalt,
Metal compounds such as lead, calcium and magnesium can be applied. As the polycondensation catalyst, titanium,
A metal compound such as antimony, germanium or tin can be applied. In addition to these catalysts, it is also possible to add thermal oxidation stabilizers and phosphorus compounds.

(Melting Mixing of Metal Salt Compound) The mixing of the metal salt compound into the polyester can be performed by a single-screw extruder, a twin-screw extruder, or addition to the melting step of the polyester during molding. As an example, a case where a metal salt compound is mixed with polyester using a twin-screw extruder will be described.

A twin-screw extruder (TEM-37BS manufactured by Toshiba Machine Co., Ltd.) is used for mixing the metal salt compounds. The metal salt compound is uniformly mixed with the polyester under the conditions of a resin temperature of 250 ° C. at the time of mixing, a screw rotation speed of 100 rpm, a vent vacuum degree of 1 to 5 hPa, and a feed rate of 15 kg / hr, and then extruded in a strand shape and cut into a chip shape under water cooling. . Further, when the metal salt compound is mixed, it is possible to simultaneously blend an ultraviolet absorber and a pigment that does not adversely affect transparency.

(Characteristic Value) In the present invention, the characteristics of the transparent flexible polyester are expressed using characteristic values such as elastic modulus, crystallization index Xc and haze.

The elastic modulus is an index representing the flexibility of the transparent flexible polyester. Flexibility is, for example, the structure of the hard segment,
It can be controlled according to the type and amount of soft segment used. The elastic modulus becomes harder as its value increases, and conversely becomes softer as it becomes smaller. Generally, the transparent flexible polyester exhibits flexibility by setting the elastic modulus of a sheet having a thickness of 100 μm to 1200 MPa or less, but preferably 1150 MPa or less, and particularly preferably 1100 MPa or less. On the other hand, the lower limit of the elastic modulus is preferably 10 MPa, more preferably 11 MPa, and particularly preferably 12 MPa from the viewpoint of moldability. When the elastic modulus is less than 10 MPa, not only is it difficult to mold, but also difficult to handle, which is not practical. Further, the composition ratio of the soft segment becomes high, which is disadvantageous in terms of cost.

The crystallization index Xc is a scale showing the degree of microcrystallization and is an important index for handling. Xc
Can be controlled, for example, by the structure of the hard segment. From the viewpoint of handleability, the larger Xc is, the better. It is necessary to be 5% or more, preferably 6% or more, and particularly preferably 7% or more. On the other hand, it is technically difficult to make the crystallization index Xc exceed 55% in terms of polymer structure.
Even if the crystallization index Xc is 55% or less, if the crystallization index Xc is 5% or more, it generally has sufficient handling property. Therefore, it is a technique to actively set the crystallization index Xc to more than 55%. It is not very practical in consideration of the difficulty.

The haze is an index showing the transparency of a molded product of transparent flexible polyester. The smaller the haze, the more excellent the transparency is, and it is important that the haze is 10% or less, and preferably 9% or less when a sheet having a thickness of 100 μm is formed.
It is particularly preferably 8% or less. When the haze exceeds 10%, whitening is remarkable and it can no longer be said that it is transparent. On the other hand, the lower limit of haze is preferably 0.1%. Even if the haze is less than 0.1%, there is no great difference in transparency by visual evaluation, and it is not practical to actively set the haze to less than 0.1% in view of technical difficulty.

Furthermore, the haze is further improved by containing the metal salt compound of the present invention, and the transparency is further improved. The effect of improving the haze by containing the metal salt compound is 0.
It is preferably smaller than 2%. When the haze improving effect is 0.2% or less, there is almost no difference in transparency visually. A preferable haze improving effect is 0.3% or more, and particularly preferably 0.4% or more.

Generally, the Tg of a flexible polyester is at room temperature or lower, and when the Tg is high, the flexibility becomes insufficient under normal use conditions. The transparent flexible polyester of the present invention is also T
g is low. Therefore, even if the molded product obtained by melt molding is transparent immediately after molding, if it is left in an atmosphere of Tg or higher, crystals may gradually grow and the transparency may deteriorate due to whitening. . This phenomenon means that crystallization progressed in the supercooled state (amorphous state) by rapidly cooling from the molten state in the temperature atmosphere of Tg or higher.

However, since the transparent flexible polyester of the present invention has a molded body obtained by rapidly cooling it from a molten state, it has already been crystallized in the course of this cooling process, and therefore, even if it is left in an atmosphere at a temperature of Tg or higher, it no longer exists. The crystal never grows,
Does not bleach. This is the greatest feature of the transparent flexible polyester of the present invention.

The transparent flexible polyester thus obtained can be used as a molded product such as a sheet, a film, an engineering plastic, a tube, a packaging bag, a skin, a stationery. At this time, the polyester may be laminated and blended with olefins such as polyethylene and polypropylene, polyesters, and other resins such as polycarbonate and vinyl chloride.

Examples Next, the transparent flexible polyester of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples shown below. The characteristics of the transparent flexible polyester obtained in this example were evaluated by the following methods.

(1) Preparation of measurement sample The obtained resin was dried under reduced pressure at 70 ° C for a whole day and night, and then an unstretched sheet having a thickness of about 100 µm was prepared by the following operation.

Place a Kapton film (Toray DuPont) on a flat metal plate, a metal spacer (thickness: 0.5 mm) cut into a desired mold in this order, and then add resin pellets sufficient to fill the mold. It was put in a mold, and a Kapton film and a metal plate were stacked again in that order. These were transferred to the press surface of a hydraulic press (Shindo type F type, manufactured by Shindo Metal Industry Co., Ltd.), melted for 4 minutes at a temperature 20 to 30 ° C. higher than the melting point, and then 9.8 MPa (100 kgf / cm ² ) at the same temperature. In 1
Pressed for minutes. Within 5 seconds after pressing, the sheet was transferred to ice water and rapidly cooled. After the rapid cooling, the water adhering to the surface of the sheet was immediately wiped off and stored in a dry oven at 25 ° C for 24 hours.

(2) Elastic Modulus, Yield Strength, Breaking Strength, and Breaking Elongation A measurement sample stored in a dry oven was kept at room temperature for 3 days.
After leaving it for 0 minutes or more, according to ASTM-D638,
Tensile tester (A & D Co., Ltd., RTC-115
0A), measurement temperature 23 ° C., sample length (distance between chucks) 60 mm, sample width 10 mm, pulling speed 50 mm /
Min, full scale 2 to 40 kg, sheet elastic modulus (MPa), yield strength (MPa), breaking strength (MPa),
And the elongation at break (%) were measured.

(3) Crystallization index Xc The sample for measurement was taken out from the storage container, left at room temperature for 30 minutes or longer, and cut into a size of 20 mm × 18 mm to obtain a wide-angle X-ray diffraction measurement sample.

For X-ray diffraction measurement, refer to "X-ray Analysis Guide
Edition, p. 84, published on June 30, 1985, Rigaku Denki Co., Ltd., and a 2θ-X-ray intensity profile was obtained by the reflection method under the following measurement conditions.

(Measurement condition)   X-ray generator: Rigaku's Geiger flex   Target: Cu   Voltage, current: 40kV, 37.5mA   Scanning speed: 0.5 ° / min   Slit: Divergence slit 1 °                     Scattering slit 1 °                     Light receiving slit 0.3 mm   Monochromator: Counter monochromator [graphite (0002)] (Definition of crystallization index Xc)   The definition of the crystallization index Xc will be described with reference to FIG.

First, a moving average approximation line (section: 30) of the 2θ-X-ray intensity profile obtained by X-ray measurement was obtained.

Since the X-ray intensity on the vertical axis changes depending on the sample thickness, roughness, etc., assuming that the ratio of peak heights does not change even if expanded or contracted, the X-ray intensity at each θ = 13 ° is 250 cps. Each value was linearly transformed so that Next, two points at 2θ of 9 ° and 35 ° of this moving average approximation line (A or B) are connected to form a base line C, and 2θ is in the range of 9 ° to 35 ° (B or A). ) And a baseline C surrounded by an area S (S _BC or S
_AC ) asked.

At this time, the glycol component of the hard segment is EG1.
The scattering profile when the content is 00 mol% (Comparative Example 3 as a specific example) is derived from an amorphous structure, and the scattering profile when the glycol composition of the hard segment is changed while the composition ratio of the soft segment is kept constant (Specific Example) The crystallinity index Xc was defined as follows, assuming that the difference from Example 1) was derived from the crystal structure.

Crystallization index Xc (%) = ((S _BC −S _AC ) / S _AC ) × 100 In the above formula, S _AC represents the area of the scattering profile due to the amorphous structure, and S _BC is due to the crystal structure. The area of the scattering profile is shown.

(4) Haze After removing the sample for measurement from the storage container and leaving it at room temperature, a haze meter (made by Nippon Denshoku Industries Co., Ltd., Model N
DH2000). The measured value was converted into a haze value of a sheet thickness of 100 μm by the following formula.

Haze (%) = Hz (%) × 100 (μm) / A (μm) Here, Hz (%) is the actually measured haze value of the measurement sample, and A represents the actually measured thickness (μm) of the measurement sample.

(5) Reduced viscosity Reduced viscosity (ηsp / C) is 0.1 g of sample in 25 ml of phenol / tetrachloroethane = 60/40 (weight ratio)
Dissolve in a mixed solution of and use an Ostwald viscometer at 30 ° C
It was measured at.

(6) Composition analysis For the composition analysis of polyester, the sample was dissolved in a mixed solvent of deuterated chloroform / trifluoroacetic acid = 90/10 (volume ratio), and an NMR spectrometer (Varian, Unit-
500).

(7) Melting point (7-1) Melting point of metal salt compound Differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-50)
Was used to fill an aluminum pan with 5 to 10 mg of a sample, and the temperature was raised at 20 ° C./min in a nitrogen atmosphere. The peak temperature in the highest temperature region of the endothermic peak that appears when the temperature was raised was taken as the melting point (Tm).

(7-2) Melting point of polyester Differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-
50), 10 mg of the sample was filled in an aluminum pan, and heated to 290 ° C. at a heating rate of 20 ° C./min in a nitrogen atmosphere,
After holding at the same temperature for 3 minutes, the aluminum pan was put into liquid nitrogen and rapidly cooled. The rapidly cooled aluminum pan was set again on the differential scanning calorimeter, and the peak temperature of the endothermic peak that appeared when the temperature was raised at a heating rate of 20 ° C./min was taken as the melting point.

Example 1 Dimethyl terephthalate (DM
T) 83,800 parts by weight, EG 26,200 parts by weight, TMG 38,100 parts by weight, DDO (Unichema, PRIPOL2033) 10,000 parts by weight,
100 parts by weight of tetrabutyl titanate (TBT) as a catalyst,
As a stabilizer, 200 parts by weight of Irganox 1010 (IRG, manufactured by Ciba Geigy) and 200 parts by weight of ADEKA STAB PEP-36 (PEP, manufactured by Asahi Denka Co., Ltd.) were charged, and the internal temperature was adjusted to 120 to 226 ° C.
The temperature was raised for 1 minute and the temperature was held for 20 minutes to carry out a transesterification reaction.

Then, the transesterified product was transferred to a polycondensation reaction kettle and the temperature inside the can was raised from 220 ° C to 250 ° C in 75 minutes.
At the same time, the internal pressure of the can was gradually reduced to 0.8 hPa. Under this condition, the polycondensation reaction was continued until the melt viscosity of the content reached 3000 dPa · s, and then the content was discharged into water under slight pressure with nitrogen and cut into chips. The composition of the obtained polyester is shown in Table 1, and the properties and sheet properties of the polyester are shown in Table 2.

(Examples 2 to 4, Comparative Examples 1 to 3) Polyesters were obtained in the same manner as in Example 1 except that the compositions of EG and TMG were changed as shown in Table 1. Table 2 shows the properties and sheet properties of the obtained polyester.

(Example 5) In accordance with Example 1, DMT 68,300 parts by weight, EG 22,700 parts by weight, TMG 30,000 parts by weight, DDO 30,000 parts by weight, TBT 100
By weight, IRG (200 parts by weight) and PEP (200 parts by weight) were subjected to a transesterification reaction and a polycondensation reaction to obtain a transparent flexible polyester. The composition of the obtained polyester is shown in Table 1, and the properties and sheet properties of the polyester are shown in Table 2.

(Examples 6 to 9 and Comparative Examples 4 to 5) Polyesters were obtained in the same manner as in Example 5 except that the compositions of EG and TMG were changed as shown in Table 1. Table 2 shows the properties and sheet properties of the obtained polyester.

(Example 10) DMT 44,300 parts by weight, EG 4,900 parts by weight, TMG 23,900 parts by weight, DDO 60,000 parts by weight, TBT 100 parts by weight, IRG 200 parts by weight, and PEP 200 parts by weight were transesterified in the same manner as in Example 1. The reaction and polycondensation reaction were performed to obtain a transparent flexible polyester. The composition of the obtained polyester is shown in Table 1, and the properties and sheet properties of the polyester are shown in Table 2.

(Examples 11 to 14 and Comparative Examples 6 to 7) Polyesters were obtained in the same manner as in Example 10 except that the compositions of EG and TMG were changed as shown in Table 1. Table 2 shows the properties and sheet properties of the obtained polyester.

(Example 15) In accordance with Example 1, 2,6-dimethylnaphthalate (DM
N) 54,100 parts by weight, EG 22,300 parts by weight, TMG 29,500 parts by weight, DDO 18,800 parts by weight, TBT 100 parts by weight, IRG 200 parts by weight, PEP 200 parts by weight, through a transesterification reaction and a polycondensation reaction to obtain a transparent flexible polyester. Obtained. The composition of the obtained polyester is shown in Table 1, and the properties and sheet properties of the polyester are shown in Table 2.

(Example 16) According to Example 1, 4,4'-dimethylbiphenyl carbonate (DMB) 38,000 parts by weight, EG 4,500 parts by weight, TMG 23,
500 parts by weight, DDO 39,700 parts by weight, TBT 100 parts by weight, IRG 20
0 parts by weight and 200 parts by weight of PEP were subjected to transesterification reaction and polycondensation reaction to obtain a transparent flexible polyester. The composition of the obtained polyester is shown in Table 1, and the properties and sheet properties of the polyester are shown in Table 2.

(Example 16) The transparent flexible polyester obtained in Example 1 was dried under reduced pressure at 70 ° C for one day, and then a twin-screw extruder (PCM manufactured by Ikegai Tekko KK, PCM).
-30) is used to melt at a resin temperature of 220 ° C. and a screw rotation speed of 150 rpm, and the surface temperature is 3 from the T-die.
It was extruded on a chill roll at 0 ° C. to obtain an unstretched sheet having a thickness of 450 μm. The properties of the obtained sheet are shown in Table 3.

(Example 17) The transparent flexible polyester obtained in Example 8 was dried under reduced pressure at 70 ° C for a whole day and night, and then a twin-screw extruder (PCM manufactured by Ikegai Tekko KK, PCM).
-30) is used to melt at a resin temperature of 200 ° C. and a screw rotation speed of 150 rpm, and a surface temperature of 3 is obtained from a T-die.
It was extruded on a chill roll at 0 ° C. to obtain an unstretched sheet having a thickness of 450 μm. The properties of the obtained sheet are shown in Table 3.

(Example 18) The transparent flexible polyester obtained in Example 11 was dried under reduced pressure at 70 ° C for one day, and then a twin-screw extruder (PCM manufactured by Ikegai Tekko KK, PCM).
-30) is used to melt at a resin temperature of 200 ° C. and a screw rotation speed of 150 rpm, and a surface temperature of 3 is obtained from a T-die.
It was extruded on a chill roll at 0 ° C. to obtain an unstretched sheet having a thickness of 450 μm. The properties of the obtained sheet are shown in Table 3.

(Comparative Example 8) The copolyester obtained in Comparative Example 3 was dried under reduced pressure at 70 ° C for a whole day and night, and then a twin-screw extruder (PCM-
30) is used to melt at a resin temperature of 270 ° C. and a screw rotation speed of 150 rpm, and a surface temperature of 30 is obtained from a T-die.
It was extruded onto a chill roll at ℃ to obtain an unstretched sheet having a thickness of 450 μm. The properties of the obtained sheet are shown in Table 3.

(Comparative Example 9) The copolyester obtained in Comparative Example 5 was dried under reduced pressure at 70 ° C for one day, and then a twin-screw extruder (PCM- manufactured by Ikegai Tekko KK).
30) is used to melt at a resin temperature of 220 ° C. and a screw rotation speed of 150 rpm, and a surface temperature of 30 is obtained from a T-die.
It was extruded onto a chill roll at ℃ to obtain an unstretched sheet having a thickness of 450 μm. The properties of the obtained sheet are shown in Table 3.

(Comparative Example 10) The copolyester obtained in Comparative Example 6 was dried under reduced pressure at 70 ° C for a whole day and night, and then a twin-screw extruder (PCM-
30) is used to melt at a resin temperature of 200 ° C. and a screw rotation speed of 150 rpm, and a surface temperature of 30 is obtained from a T-die.
It was extruded onto a chill roll at 0 ° C. to obtain an unstretched sheet having a thickness of 450 μm. The properties of the obtained sheet are shown in Table 3.

(Examples 19 to 21, Comparative Example 11) The sheets obtained in Examples 16 to 18 and Comparative Example 8 were heat-treated in an oven under a nitrogen atmosphere at 70 ° C for 24 hours. The measurement results are shown in Table 4.

Examples 22 to 30 and Comparative Examples 12 to 16 are examples of copolyesters containing a metal salt compound.

(Examples 22 to 25, Comparative Examples 12 and 13) In Example 22, the polyester obtained in Example 4 was used,
2.5 wt% of the metal salt compound shown in Table 5 was melt-mixed with the polyester as a metal element.

Further, in Examples 23 and 24, the polyester obtained in Example 5 was used, and the metal salt compounds shown in Table 5 were used as metal elements in the polyester in Example 23 at 1.5% by weight and in Example 24 at 2%. 0.5 wt% was melt mixed.

In Example 25 using the polyester obtained in Example 10,
2.5 wt% of the metal salt compound shown in Table 5 was melt-mixed with the polyester as a metal element.

Further, in Comparative Example 12, the polyester obtained in Example 8 was used, and the metal salt compound shown in Table 5 was melt-mixed with the polyester as a metal element in an amount of 5.2% by weight.

Comparative Example 13 uses the polyester obtained in Comparative Example 2,
2.5 wt% of the metal salt compound shown in Table 5 was melt-mixed with the polyester as a metal element. The obtained results are shown in Tables 5 and 6.

From Tables 5 and 6, the sheet containing the metal salt compound as a metal element in an amount of 0.5 to 5.0% by weight with respect to the polyester has a smaller haze than the sheet containing no metal salt compound, and has a transparency. Had been improved. Moreover, the reduction rate of haze tended to increase as the soft component increased.

However, in Comparative Example 12 in which the content of the metal salt compound exceeded 5% by weight, the molten resin gelled and a sheet could not be obtained.

Also, as the glycol component of the copolyester,
In Comparative Example 13 in which the composition ratio of TMG was 96 mol% or more, the obtained sheet was whitened due to crystallization, and the transparency was not improved even when the metal salt compound was contained.

(Example 26). In the transesterification reactor, DMT 69,800 parts by weight, EG 35,20
PTMG with 0 parts by weight, TMG 13,700 parts by weight and number average molecular weight of 1,000
(Hodogaya Chemical Co., Ltd., PTG1000) 30,000 parts by weight, antimony trioxide 53 parts by weight as catalyst, zinc acetate dihydrate 53 parts by weight, Irganox 1330 as thermal oxidation stabilizer
(Ciba-Geigy Co., Ltd.) 200 parts by weight was charged and the internal temperature was 120 °
To 220 ° C over 90 minutes, and held at the same temperature for 20 minutes to carry out a transesterification reaction.

Subsequently, the transesterification reaction completed product was transferred to a polycondensation reaction kettle and the kettle temperature was raised from 220 ° C to 250 ° C in 75 minutes. At the same time, the pressure inside the kettle is gradually reduced to 0.
It was set to 9 hPa. Under this condition, the polycondensation reaction was continued until the melt viscosity of the content reached 300 Pa · s, and then the content was extruded into the water under nitrogen pressure and cut into a chip shape.

This resin, sodium caprylate as a metal salt compound (C ₈ -Na) to resin is contained 2.5 wt% as the metal element, and vacuum dried overnight at 100 ° C.. Vent type twin-screw extruder (Toshiba Machinery, TEM-37B)
S), resin temperature 250 ℃, screw rotation speed 100rp
The metal salt compound was uniformly melt-mixed at m, a vent vacuum degree of 1 hPa, and a resin supply rate of 15 kg / hr.

Then, the resin mixed with the metal salt compound is mixed at 100 ° C.
After drying under reduced pressure for 24 hours, a twin-screw extruder (made by Ikegai Tekko Co., Ltd.,
PCM-30), resin temperature 200 ℃, screw rotation speed
The mixture was melt-mixed at 150 rpm and the molten resin was melt-extruded from a T-die onto a chill roll having a surface temperature of 30 ° C. to obtain an unstretched sheet having a thickness of 500 μm. The obtained results are shown in Tables 5 and 6.

(Examples 27 to 28, Comparative Examples 14 to 15) In Example 26, the composition ratio of TMG / EG, PTMG
An unstretched sheet was produced in the same manner as in Example 26 except that the molecular weight and composition ratio of, and the type and content of the metal salt compound were changed. The obtained results are shown in Tables 5 and 6.

When the content of the metal salt compound was 0.5 to 5.0% by weight as a metal element with respect to the polyester, the haze was small, and the effect of transparency was large. Particularly, in Example 27, by melting and mixing the metal salt compound in an appropriate amount, blocking between the sheets immediately after film formation was eliminated, and a transparent sheet could be obtained.

However, in Comparative Example 14 in which the content of the metal salt compound is 0.4% by weight as a metal element with respect to the polyester, even if the metal salt compound is contained, the haze is reduced by only 0.1%, and transparency is improved. Little effect was seen. On the other hand, in Comparative Example 15 in which the content of the metal salt compound was 5.3% by weight as the metal element with respect to the polyester, the molten resin was gelled and a sheet could not be obtained. Also,
The decrease in molecular weight was also large.

(Example 29) DMT 49,300 parts by weight and EG 29,200 were placed in an ester exchange reaction kettle.
10 parts by weight, TMG 10,600 parts by weight, 150 parts by weight of Irganox 1330 (manufactured by Ciba Geigy) as a thermal oxidation stabilizer, 38 parts by weight of antimony trioxide as a catalyst, 63 parts by weight of zinc acetate dihydrate, and transesterification. The reaction was carried out. Then, the transesterification product was treated with DiA (Unichema, PRIPO
L1009) 22,500 parts by weight was added, and the mixture was stirred at 220 ° C for 30 minutes,
A polycondensation reaction was performed.

This resin, a C ₈ -Na added 2.5% by weight relative to the resin as a metal salt compound, followed by uniformly melt mixed at 240 ° C., to obtain a sheet by heat pressing. The obtained results are shown in Tables 5 and 6.

(Example 30, Comparative Examples 16 to 17) In Example 29, the copolyester TMG / E was used.
A sheet was produced in the same manner as in Example 29 except that the G composition ratio, the composition ratio of dimer acid (DiA), the type and content of the metal salt compound were changed. The obtained results are shown in Tables 5 and 6.

The sheets shown in the examples have improved transparency and handleability, but do not contain Comparative Example 16 in which the composition ratio of EG is 97 mol% based on the total glycol components constituting the hard segment of polyester, and a metal salt compound. In Comparative Example 17, blocking occurred and a sheet could not be obtained.

EFFECT OF THE INVENTION The transparent flexible polyester of the present invention is a transparent flexible polyester having a copolyester composed of a hard segment and a soft segment as a main constituent, and the elasticity of an unstretched sheet obtained by melt-molding the transparent flexible polyester. Rate is 1500 MPa or less, crystallization index Xc measured by wide-angle X-ray is 5% or more, and haze (1
Since it is 15% or less (converted to 00 μm), it has excellent transparency, flexibility, and handleability that could not be achieved in the past. Therefore, sheets, films, engineering plastics, tubes, packaging bags, skins,
It can be used in a wide range of applications such as molded articles such as stationery. Furthermore, the transparent flexible polyester of the present invention is not only a single molded article, but also a laminate of the transparent flexible polyester of the present invention whose flexibility is changed, or a polyolefin such as polyethylene or polypropylene, a polyester,
By laminating and blending with other resins such as polycarbonate and vinyl chloride, it is possible to impart other functions while maintaining the effects of the present invention such as transparency, flexibility and blocking properties.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Shimoyama 2-1-1 Katata, Otsu-shi, Shiga Toyo Spinning Co., Ltd. Research Institute (72) Inventor Masayuki Tsutsumi 2-1-1 Katata, Otsu, Shiga Toyo Boseki Co., Ltd. Research Institute (56) Reference JP 2000-302888 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 63/00-63/91 WPI / L ( QUESTEL)

Claims (6)

(57) [Claims] 1. A transparent flexible polyester mainly comprising a copolyester composed of a hard segment and a soft segment, wherein an unstretched sheet obtained by melt-molding the transparent flexible polyester has an elastic modulus of 1500 M.
Pa or less, crystallization index Xc measured by wide-angle X-ray is 5% or more, and haze (converted to 100 μm) of the sheet is 15%
A transparent flexible polyester characterized in that: 2. At least 70 mol% or more of the dicarboxylic acid component constituting the hard segment is terephthalic acid (T
PA), 2,6-naphthalenedicarboxylic acid (NDA),
The transparent flexible polyester according to claim 1, which is at least one kind of 4,4'-biphenyldicarboxylic acid (BPA). 3. The glycol component constituting the hard segment contains 1,4-tetramethylene glycol (TMG) and ethylene glycol (EG), and the composition ratio to the total glycol component constituting the hard segment is
TMG is 20-95 mol% and EG is 5-80 mol%, The transparent flexible polyester of Claim 1 or 2 characterized by the above-mentioned. 4. The soft component constituting the soft segment is a long chain aliphatic dicarboxylic acid having a number average molecular weight of 100 to 1,000, a long chain aliphatic glycol having a number average molecular weight of 100 to 1,000, and a number. Average molecular weight is 500 ~
2. At least one kind of polyalkylene oxide glycol having a molecular weight of 4,000.
The transparent flexible polyester according to any one of 2 and 3. 5. The soft component constituting the soft segment is dimer diol (DDO), and the composition ratio of DDO to the total glycol component of polyester is 1 to 1.
It is 60 mol%, The transparent flexible polyester in any one of Claim 1, 2, 3 characterized by the above-mentioned. 6. The transparent flexible polyester comprises a metal salt compound having a metal element of Group Ia or Group II-a of the Periodic Table of 0.5 to 0.5 as a metal element with respect to polyester.
The transparent flexible polyester according to claim 1, wherein the transparent flexible polyester is contained in an amount of 5.0% by weight.