JPH06107777A - Copolymerized polyester and thermoforming sheet composed of the polyester - Google Patents

Abstract

PURPOSE:To provide a copolymerized polyester containing a specific diphenylsulfone-type structure unit and a specific diphenylpropane-type structure unit at a specific ratio, having excellent transparency and moist-heat deformation resistance and useful for a thermoforming sheet, etc. CONSTITUTION:The objective copolymerized polyester is composed of glycol unit composed mainly of ethylene glycol unit and dicarboxylic acid unit composed mainly of terephthalic acid unit and contains a diphenylsulfone-type structure unit of formula I ((j) and (k) are 1-3) or formula II or a diphenylpropane- type structure unit expressed by formula III ((m) and (n) are 1-3) or formula IV. The sum of the diphenylsulfone-type structure unit and the diphenylpropane- type structure unit is 0.1-10mol% based on the total structure unit.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel polyethylene terephthalate copolymer polyester and a thermoforming sheet comprising the copolymer polyester.

[0002]

2. Description of the Related Art Polyethylene terephthalate is excellent in various properties such as transparency, thermoformability, mechanical properties, heat resistance, weather resistance, and chemical resistance, and is particularly inexpensive and less likely to cause environmental pollution. In recent years, it has been widely used as a material for packaging products such as food containers and blister packs instead of vinyl chloride resin. However, a packaging material obtained by thermoforming a polyethylene terephthalate sheet by vacuum forming or the like is generally easily deformed under high temperature and high humidity. For example, when a product packaged in a vacuum-formed container of polyethylene terephthalate sheet is transported by ship, it is exposed to high temperature and high humidity conditions of the cargo hold for a long period of time. It is likely to cause a problem of causing deformation and significantly impairing the value of the product. Moreover, when polyethylene terephthalate is vacuum-molded, there is a drawback that whitening is likely to occur and transparency is likely to be impaired depending on molding conditions.

Conventionally, in order to solve the above problems, in particular, to improve the resistance to moist heat deformation, (1) a method in which the sheet heating temperature during vacuum forming is raised to a high temperature, and (2) a mold temperature during vacuum forming. The residual stress in the molded product is removed by various methods such as a method of molding at a high temperature and (3) a method of heat-treating the obtained vacuum-molded product to impart wet heat deformation resistance. However, with those methods,
There are drawbacks such as an increased incidence of molding defects such as whitening of molded products due to crystallization, and a long molding cycle leading to an increase in cost, which is not sufficiently satisfactory.

[0004]

However, the object of the present invention is to provide transparency, thermoformability, mechanical properties, heat resistance, weather resistance,
It retains the excellent properties inherent to polyethylene terephthalate such as chemical resistance, and does not have the above-mentioned thermoforming defects such as whitening of molded products due to crystallization and prolonged molding cycle, and high temperature and high humidity conditions. It is an object of the present invention to provide a polyethylene terephthalate-based copolyester and a thermoforming sheet made of the copolyester, which gives a molded article which is not deformed even if it is exposed to a long time.

[0005]

The inventors of the present invention have conducted research to achieve the above-mentioned object, and as a result, in polyethylene terephthalate, the glycol unit and dicarboxylic acid unit were composed of only ethylene glycol unit and terephthalic acid unit. Instead of constituting, a copolymerized polyester in which a part of all structural units consisting of glycol units and dicarboxylic acid units are replaced with specific structural units retains the above excellent properties such as thermoformability that polyethylene terephthalate originally has. It was found that a vacuum-formed product which has no or almost no deformation even when exposed to high temperature and high humidity for a long time and which has good transparency can be provided. After further research, when the copolyester was used, not only in vacuum molded products, but also in molded products manufactured by other thermoforming techniques such as pressure molding, press molding and blow molding. However, the inventors have completed the present invention by finding that the improvement of the resistance to moist heat deformation and the prevention of whitening are achieved.

That is, the present invention comprises a glycol unit mainly containing ethylene glycol units and a dicarboxylic acid unit mainly containing terephthalic acid units,
Alternatively, the diphenylsulfone-type structural unit (I) represented by the following chemical formula 6 and the diphenylpropane-type structural unit (II) represented by the following chemical formula 7 or the following chemical formula 8 are combined with the structural unit (I) based on all structural units. It is a copolyester containing 0.1 to 10 mol% of the total content of units (II), and a thermoforming sheet comprising the copolyester.

[0007]

[Chemical 5]

(Wherein j and k represent 1, 2 or 3 respectively)

[0009]

[Chemical 6]

[0010]

[Chemical 7]

(In the formula, m and n respectively represent 1, 2 or 3)

[0012]

[Chemical 8]

The molecular main chain of the copolymerized polyester of the present invention contains about 50 mol% of glycol units and dicarboxylic acid units as main structural units. The main portion of the dicarboxylic acid unit, preferably 40 to 50 mol% of all structural units, is occupied by terephthalic acid units, and the main portion of the glycol unit, preferably 4 of all structural units.
Ethylene glycol units account for 0 to 50 mol%. In the copolyester of the present invention, it is necessary that both the structural unit (I) and the structural unit (II) be present as structural units other than the terephthalic acid unit and the ethylene glycol unit. The copolymerized polyester has, as the structural unit (I), a structural unit (I-1) represented by Chemical Formula 5 above and a structural unit (I-) represented by Chemical Formula 6 above.
2) and at least one of the structural unit (II-1) represented by the chemical formula 7 and the structural unit (II-2) represented by the chemical formula 8 as the structural unit (II). contains. Therefore, in the copolyester of the present invention, some of the glycol units are structural units (I-
1) and / or a structural unit (II-1), a part of the dicarboxylic acid unit is a structural unit (I-2) and / or a structural unit (II-2), or both of them. . The content of these structural units (I) and structural units (II) is 0.
It is within the range of 1 to 10 mol%. When the sum of the content ratios of the structural unit (I) and the structural unit (II) is less than 0.1 mol%, the resulting thermoformed article does not have sufficient resistance to wet heat deformation, and the sheet is thermoformed. When attached to, whitening easily occurs. On the other hand, when the sum of the content ratios of the structural unit (I) and the structural unit (II) exceeds 10 mol%, the adhesion of the sheet to the mold during thermoforming is deteriorated and the resulting molded article has a morphological defect. Is likely to occur. From the viewpoint that the morphology-imparting property at the time of thermoforming and the wet heat deformation resistance and the transparency of the obtained molded article are particularly good, the content of the structural unit (I) and the structural unit (II) is respectively Within the range of 0.1 to 6 mol%, and the sum of these contents is 0.5 to 9 mol%.
It is preferably within the range.

The copolymerized polyester of the present invention may contain a small amount of other dicarboxylic acid units in the molecule, preferably 5 mol% or less of all structural units. Other dicarboxylic acid units include, for example, isophthalic acid, phthalic acid,
Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, paraphenylenedicarboxylic acid, sodium sulfoisophthalate; succinic acid,
One or more units of a dicarboxylic acid unit such as an aliphatic dicarboxylic acid such as glutaric acid, adipic acid, suberic acid or dodecanedioic acid may be contained as necessary.
The copolyester of the present invention may contain a small amount, preferably 5 mol% or less of all structural units, of other glycol units in the molecule. Examples of other glycol units include glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and neopentyl glycol. One type or two or more types of units can be contained as necessary. Further, the above-mentioned copolymerized polyester has a trivalent or higher valent unit derived from a trifunctional or higher polyfunctional compound such as trimellitic acid or pentaerythritol, as long as the thermoplastic polyester is not substantially impaired. A small amount may be included if necessary.

The copolyester of the present invention is not necessarily limited, but for the purpose of producing, for example, a thermoforming sheet, the intrinsic viscosity (measured in an equal weight mixed solvent of phenol / tetrachloroethane at 30 ° C.). Is 0.
It is preferably in the range of 4 to 1.2 dl / g.

The copolymerized polyester of the present invention can be produced according to the method generally adopted for producing ordinary polyesters such as polyethylene terephthalate. For example, a dicarboxylic acid raw material consisting of a dicarboxylic acid mainly composed of terephthalic acid or a lower alkyl ester thereof and a glycol raw material mainly composed of ethylene glycol are subjected to an esterification reaction or a transesterification reaction to produce a low polymer, This low polymer is melt-polycondensed to produce polyester, and then this polyester is made into chips of any shape such as dice or columnar shape, and if desired, the chips are solid-phase polymerized to obtain chip-shaped polyethylene. A terephthalate-based polyester can be produced. In this production method, an ethylene oxide adduct of bis (4-hydroxyphenyl) sulfone represented by the following chemical formula 9 and / or 2,2-bis (4-hydroxyphenyl) propane represented by the following chemical formula 10 as a part of the glycol raw material. Ethylene oxide adduct of the following, or as a part of the dicarboxylic acid raw material
Diphenylsulfone-4,4′-dicarboxylic acid represented by 1 or a lower alkyl ester thereof and / or 2,2-diphenylpropane represented by the following chemical formula 12
The copolymerization of the present invention can be achieved by using the desired comonomer which provides the structural unit (I) and the structural unit (II), respectively, by using 4 ', 4 "-dicarboxylic acid or its lower alkyl ester, or both of them. A polyester is obtained.

[0017]

[Chemical 9]

(Where j and k are as defined above)

[0019]

[Chemical 10]

(Where m and n are as defined above)

[0021]

[Chemical 11]

[0022]

[Chemical 12]

In the above-mentioned method, the esterification reaction or transesterification reaction for obtaining the low polymer is carried out usually by mixing a mixture of the above-mentioned glycol raw material and dicarboxylic acid raw material under atmospheric pressure or at an absolute pressure of about 3 Kg / cm ² or less. Or an esterification reaction at about 230 to 280 ° C. under pressure,
Or about 160-under normal pressure or its pressure condition.
It is carried out by transesterification at 230 ° C. In this case, the dicarboxylic acid raw material: glycol raw material is used in a molar ratio of about 1: 1 in the case of the esterification reaction.
˜about 1: 1.5, and in the case of transesterification, it may be about 1: 2 to about 1: 3. The above-mentioned melt polycondensation for obtaining a polyester from a low polymer is usually carried out at a temperature of about 260 to 290 ° C in the presence of a polymerization catalyst such as germanium dioxide or antimony trioxide. And, by such melt polycondensation, usually about 0.40
It is possible to obtain a polyester having an intrinsic viscosity (measured at 30 ° C. in an equal weight mixed solvent of phenol / tetrachloroethane) of 0.75 dl / g. Incidentally, the esterification reaction, transesterification reaction or melt polycondensation step, if necessary, tetraalkyl ammonium hydroxide,
It may be carried out by adding a diethylene glycol by-product inhibitor such as triethanolamine or triethylamine.

The polyester obtained above is formed into chips having an arbitrary shape, and if desired, the chips can be precrystallized at a temperature of usually 190 ° C. or lower and subjected to solid phase polymerization.
The solid phase polymerization is preferably carried out under reduced pressure or by heating the chip at a temperature of about 190 to 240 ° C. while flowing the chip while circulating an inert gas such as nitrogen gas. In order to obtain a thermoformed product having good mechanical properties, the intrinsic viscosity of the finally obtained polyester chip (measured in an equal weight mixed solvent of phenol / tetrachloroethane at 30 ° C.) is about 0.6.
It is desirable to carry out the solid phase polymerization so that the range is from 0 to 1.20 dl / g.

Then, a sheet for thermoforming is produced by using the polyester obtained above as a resin material. Here, "thermoforming" in the present invention (thermoformin
The g) refers to molding in which a sheet is heated and softened, and is molded by vacuum molding, pressure molding, press molding, blow molding or the like to produce a molded product having a predetermined shape. The thickness of the sheet of the present invention is not particularly limited, and may be any thickness as long as it can be used in a usual thermoforming technique. A thin sheet close to a film to a thick sheet close to a plate are included as long as a molded product having a predetermined shape can be produced by thermoforming. Usually the sheet thickness is about 10
It is in the range of 1000 μ.

Further, the thermoforming sheet of the present invention can be produced by any method known as a usual method for producing a thermoforming sheet, for example, an extrusion molding method using a T die or an annular die, a calendar roll. Sheet molding method,
It can be produced by a casting method or the like. Among them, T
The extrusion molding method using a die and the sheet molding method using a calender roll are preferable in that they have a small internal stress and can easily give a molded article having particularly good resistance to wet heat deformation.
For example, in the case of the extrusion molding method, it is preferable to extrude from a T-die at an extrusion temperature of about 270 to 310 ° C. and then cool it with a cooling roll at about 30 to 70 ° C. to produce a sheet. Also,
In order to obtain a sheet having a good surface condition, a static voltage of about 5 to 15 KV may be applied if necessary at the time of contact with the cooling roll.

The above-mentioned thermoforming sheet is formed into an arbitrary shape having, for example, recesses by a usual thermoforming technique such as vacuum forming, pressure forming, press forming, blow forming after heating or simultaneously with heating. In particular, it is suitable for vacuum forming. In the case of vacuum forming, any known vacuum forming method such as a direct vacuum forming method (straight method), a drape method, an air slip method, a snapback method and a plug assist method can be adopted. The heating temperature at the time of thermoforming using the sheet of the present invention may vary depending on the composition of the copolyester, but it is generally preferable that the sheet surface temperature is in the range of about 110 to 160 ° C. If the temperature is lower than 110 ° C., the softening of the sheet may be insufficient, and the adhesion to the mold may be incomplete, resulting in defective morphology. On the other hand, if the temperature exceeds 160 ° C., it may be difficult to form the sheet due to drawdown of the sheet, and problems such as whitening due to crystallization may occur.

The molded product obtained by thermoforming the above-mentioned thermoforming sheet can be used as a packaging container for various products such as electric products, electric parts, daily sundries and foods,
It retains its original form and dimensions without deformation, volume reduction, etc. even when placed under high temperature and high humidity conditions for a long period of time.

[0029]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. In addition,
In the following Examples and Comparative Examples, the intrinsic viscosity of the obtained polyester was measured at 30 ° C. in an equal weight mixed solvent of phenol / tetrachloroethane. Further, the resistance to moist heat deformation of the cup-shaped molded product obtained by vacuum molding was evaluated by the volume retention rate described below.

<Measurement of Volume Retention Ratio> In the following Examples and Comparative Examples, the cup-shaped molded articles produced by vacuum molding were allowed to stand in a constant temperature and constant humidity chamber at a temperature of 60 ° C. and a humidity of 80% RH for 16 hours. After that, the volume retention rate was calculated from the volumes before and after the treatment by the following formula. It can be said that the closer the volume retention rate is to 100%, the more the original volume is retained, and the better the resistance to wet heat deformation.

Volume retention rate (%) = (V ₁₆ / V ₀ ) × 100

(Here, V ₁₆ represents the volume of the cup-shaped molded product after standing in a constant temperature and humidity chamber for 16 hours, and V ₀ represents the original volume of the cup-shaped molded product.)

<Example 1> 92.4 ethylene glycol
Mol%, ethylene oxide adduct of bis (4-hydroxyphenyl) sulfone shown in Table 1 [bis (4-hydroxyphenyl) sulfone / ethylene oxide mole ratio = 1/2] 1.6 mol% and shown in Table 1 Ethylene oxide adduct of 2,2-bis (4-hydroxyphenyl) propane [2,2-bis (4-hydroxyphenyl)]
Propane / ethylene oxide molar ratio = 1/2] 6.
From the glycol raw material consisting of 7 mol% and terephthalic acid, the molar ratio of glycol raw material: terephthalic acid is 1.2:
1 to form a slurry, which is subjected to an esterification reaction under pressure (absolute pressure 2.5 kg / cm ² ) at a temperature of 250 ° C. until the esterification rate reaches 95%, thereby reducing the weight. A coalesce was manufactured. Next, 350p as a catalyst
pm antimony trioxide was added and the low polymer was polycondensed at a temperature of 280 ° C. under reduced pressure of 1 torr absolute pressure to prepare a polymer having an intrinsic viscosity of 0.65 dl / g. This polymer is extruded from a nozzle in strands and cut into a length of 3.
A cylindrical chip having a diameter of 2 mm and a diameter of 2.8 mm was manufactured. This polymer chip was dried at 150 ° C. for 5 hours and then solid-state polymerized at 205 ° C. for 15 hours while flowing under a nitrogen stream to obtain a polyester chip having an intrinsic viscosity of 0.8 dl / g. When the obtained polyester was analyzed by ¹ H-NMR (solvent: trifluoroacetic acid), it was 7.9.
The absorption of the proton of the phenylene group of the structural unit derived from the ethylene oxide adduct of bis (4-hydroxyphenyl) sulfone was observed at ppm and 7.2 ppm, and 2,2-bis (at 7.5 ppm and 7.2 ppm). Proton absorption of the phenylene group of the structural unit derived from the ethylene oxide adduct of 4-hydroxyphenyl) propane was observed, and 2,2-
Since absorption of the proton of the methyl group of the structural unit derived from the ethylene oxide adduct of bis (4-hydroxyphenyl) propane was observed, the polyester was bis (4-hydroxyphenyl) based on the integrated intensity ratio.
The ethylene oxide adduct unit of sulfone was contained in 1.0 mol% in all the structural units, and the ethylene oxide adduct unit of 2,2-bis (4-hydroxyphenyl) propane was contained in 4.0 mol% in all the structural units. It was confirmed to be a polyethylene terephthalate-based copolyester.
Using the polyester chip obtained above, a temperature of 280 to 30 was measured by a T-die extruder (Kawata Seisakusho; EMS-II).
After extruding at 0 ° C., it was cooled by a cooling roll at 40 ° C. to produce a polyester sheet having a thickness of 500 μm. The sheet produced above is heated to a surface temperature of 130 ° C., vacuum-formed, and the bottom diameter of the recess having a drawing ratio of 1 / 0.7 is 6.5 cm and the depth is 11.0 cm. A cylindrical cup-shaped molded product was manufactured (concave volume V ₀ = 425c
c). The obtained cup-shaped molded product had no whitening, was excellent in transparency, and had a good morphology conforming well to the shape of the vacuum molding mold. This cup-shaped molded article was placed in a constant temperature and constant humidity chamber at a temperature of 60 ° C. and a humidity of 80% RH as described above.
After standing for 6 hours, the volume was measured and set to V _16, and the volume retention rate was calculated by the above formula. These evaluation results are shown in Table 2 below.
Shown in.

<Examples 2 to 4> Polyethylene terephthalate-based copolyesters were produced in the same manner as in Example 1 except that the type of comonomer and the amount of copolymerization were changed as shown in Table 1 and used. A cup-shaped molded product was obtained. The results of these evaluations are shown in Table 2.

Example 5 Only ethylene glycol was used as a glycol raw material, and 90.0 mol% of terephthalic acid and 2.0 mol% of diphenylsulfone-4,4'-dicarboxylic acid were used instead of terephthalic acid alone. , 2-
Diphenylpropane-4 ', 4 "-dicarboxylic acid 8.0
A polyethylene terephthalate-based copolyester was produced in the same manner as in Example 1 except that the mixed dicarboxylic acid of mol% was used. The obtained polyester is ¹ H-N
When analyzed by MR (solvent: trifluoroacetic acid), proton absorption of the phenylene group of the structural unit derived from diphenylsulfone-4,4′-dicarboxylic acid was observed at 7.9 ppm and 7.2 ppm, and 7. 5p
Proton absorption of the phenylene group of the structural unit derived from 2,2-diphenylpropane-4 ', 4 "-dicarboxylic acid was observed at pm and 7.2 ppm, and 1.8
Since the absorption of the proton of the methyl group of the structural unit derived from 2,2-diphenylpropane-4 ′, 4 ″ -dicarboxylic acid was observed in ppm, based on the integrated intensity ratio,
The polyester contains diphenylsulfone-4,4'-dicarboxylic acid unit in an amount of 1.0 mol%, 2,2 based on all structural units.
It was confirmed to be a polyethylene terephthalate copolymer polyester containing 4.0 mol% of -diphenylpropane-4 ', 4 "-dicarboxylic acid unit. Then, a cup-shaped molded product was obtained using it. The results are shown in Table 2.

<Comparative Examples 1 and 2> Polyethylene terephthalate-based copolyesters were produced in the same manner as in Example 1 except that the type of comonomer and the amount of copolymerization were changed as shown in Table 1. A cup-shaped molded product was obtained. The results of these evaluations are shown in Table 2.

<Comparative Example 3> Polyester (polyethylene terephthalate) was produced in the same manner as in Example 1 except that no comonomer was used, and a cup-shaped molded product was obtained using the polyester. The evaluation results are shown in Table 2.

[0038]

[Table 1]

The "content of the corresponding structural unit" in the "obtained polyester" in Table 1 above means " ¹ H-NMR analysis based on the total structural units including all glycol units and all dicarboxylic acid units". It is a quantitative value based on.

[0040]

[Table 2]

From the above results, the molded articles obtained by using the thermoforming sheets of the copolyesters of the present invention in Examples 1 to 5 have a volume retention of 95% or more and a resistance to moist heat deformation. It can be seen that it is extremely good, has excellent transparency, and has a good shape.

[0042]

When thermoforming such as vacuum forming is performed using the sheet made of the copolyester of the present invention, the sheet heating temperature during thermoforming is set to a high temperature, and the mold temperature during thermoforming is controlled. A molded product that has sufficient resistance to moist heat deformation even if it is not subjected to a special method such as high temperature or heat treatment of the obtained molded product, and hardly deforms even when exposed to high temperature and high humidity conditions for a long time. Can be obtained smoothly and economically with high productivity. Moreover, the obtained molded article has no whitening and the like, is excellent in transparency, and has a good shape.

Claims (2)

[Claims] 1. A diphenyl sulfone-type structural unit (I) represented by the following chemical formula 1 or the following chemical formula 2, which comprises a glycol unit mainly containing an ethylene glycol unit and a dicarboxylic acid unit mainly containing a terephthalic acid unit. The diphenylpropane type structural unit (II) represented by Chemical formula 3 or Chemical formula 4 below is contained in an amount of 0.1 to 10 mol% as the sum of the content ratios of the structural unit (I) and the structural unit (II) based on all structural units. A copolymerized polyester characterized by being. [Chemical 1] (Wherein j and k represent 1, 2 or 3 respectively) [Chemical 3] (In the formulae, m and n each represent 1, 2 or 3.) 2. A thermoforming sheet comprising the copolyester according to claim 1.