KR100249486B1 - Transparency copolyester thick sheet - Google Patents

Abstract

The present invention relates to a transparent copolyester thick sheet excellent in transparency and various physical properties and inexpensive manufacturing cost.

The copolyester thick sheet of the present invention is an air of dimethyl-2,6-naphthalene dicarboxylate (NDC), 1,4-cyclohexanedimethanol (CHDM), dimethyl terephthalate (DMT) and ethylene glycol (EG). It is made of coalescence, has a light transmittance of 83% or more, and a haze value of 5% or less. Moreover, thickness is 3 mm or more, crystallization heat ((DELTA) Hmc) is 1.0 J / g or less, visible light refractive index is 1.35-1.70, and it has a moderately high melt viscosity.

The transparent copolyester thick sheet of the present invention can be used in various industrial applications such as automobile glass substitutes, high-rise building glass substitutes and transparent soundproof walls.

Description

Transparency Copolyester Plate

The present invention relates to a transparent copolyester thick sheet sheet having excellent transparency and various physical properties, inexpensive manufacturing cost, and thick thickness.

Polyethylene nattalate (hereinafter referred to as PET) resin has excellent physical properties, processability and economical efficiency, and thus is used in PET bottles, clothing fibers, films, and a wide variety of other fields. In recent years, the use of packaging materials is increasing rapidly due to excellent mechanical and chemical properties and high recyclability. One of the fields is a sheet, which is widely used as a thin sheet for vacuum forming (1 mm or less in thickness). However, the polyester sheet having a thickness of 1 mm to 4.5 mm has a problem in that it is difficult to manufacture due to inadequate crystallization and melting characteristics inherent in PET resin.

In general, in order to manufacture a thick sheet of thick polymer (hereinafter referred to as a thick plate sheet), it is necessary to use a polymer resin having a low crystallization rate, low crystallinity, and a moderately high melt viscosity for morphological stability in a molten state. As a new attempt to satisfy these required properties, it has been attempted to copolymerize other comonomers in PET to make modified polyester copolymers and has been successful in many parts.

As such, a method of preparing a modified polyester copolymer by copolymerizing another copolymerization monomer to PET may be broadly classified into two types.

First, a method of replacing a portion of dimethyl terephthalate (hereinafter referred to as DMT) or terephthalic acid (TPA), which is one of the monomers used in PET polymerization, with diacid or diacidester is used. As the dieside or dieside ester, isophthalic acid (hereinafter referred to as IPA) or dimethylisophthalate (DMI) is mainly used. In other words, the method is to prepare a polyester copolymer by copolymerizing DMT or TPA and DMI or IPA and ethylene glycol (EG). As in general formulas (I) and (II) below, DMT and DMI differ only in the position where the functional group is attached to the benzene ring, and the rest of the structure is the same.

[Formula (I) represents DMT, and (II) represents DMI.]

Therefore, DMI reacts well up to several mol% because of its good reactivity in the reaction system during PET polymerization. Thus, the copolyester copolymerized by several mol% of DMI has the structure of General formula (IV), and is different from the homopolyester which has the structure of General formula (III).

Due to such structural differences, the copolyester of the general formula (IV) interferes with the regularity of the molecular chain during the crystallization process, so that the crystallization rate is low and the crystallinity is low. However, as the content of DMI increases, various physical properties of the resin are drastically lowered. When the content of DMI is reduced in order to prevent such a decrease in physical properties, the crystallization rate delay effect and the crystallinity deterioration effect required for the production of the copolyester thick sheet cannot be obtained. In addition, since the copolyester of the general formula (IV) does not have an adequately high melt viscosity required for morphological stability in the molten state, a lot of difficulties arise in forming the transparent copolyester thick sheet.

Due to such a problem, the copolyester of general formula (IV) copolymerizing about 3 mol% of DMI is currently used only for the manufacture of sheets of thick bottles or thin films.

Next, a method of replacing a part of ethylene glycol (hereinafter referred to as EG), which is one of monomers used in PET polymerization, with 1,4-cyclohexanedimethanol (hereinafter referred to as CHDM) may be used.

In other words, after copolymerizing DMT or TPA with EG and CHDM to prepare a polyester copolymer, a method for producing a transparent copolyester thick sheet using the same.

CHDM is a structure like the general formula (V), and because the length of the molecule is longer than EG, it interferes with the regularity of the crystal in the copolyester to delay the crystallization rate and decrease the crystallinity.

In addition, since CHDM does not break the molecular chain like DMI, even if the copolymerization content is increased, the reactivity and the physical properties of the polymer do not significantly decrease, and CHDM also has the high melt viscosity required for the manufacture of the thick sheet of the polymer resin.

However, in order to obtain a crystallization rate, low crystallinity characteristics and relatively high melt viscosity characteristics that are sufficiently slow to enable the formation of the transparent thick sheet, CHDM should be copolymerized in a large amount up to about 30 mol%. As a result, the manufacturing cost of the product is also very expensive, and there is a significant limitation in the range of its use. In addition, in order to obtain sufficient mechanical properties, a high degree of polymerization is essential, but the crystallinity is very low, and the degree of polymerization is inevitably raised in the melt polymerization. Therefore, considerable effort is required to obtain sufficient degree of polymerization. Estman Chemical Co. produces and sells these polymers under the trade name PETG.

In many industrial fields such as transparent light shielding walls and high-rise building glass substitutes, there is a need for development of a transparent copolyester thick sheet having excellent transparency and processing properties and low manufacturing cost in order to be usefully used.

An object of the present invention is to provide a transparent copolyester thick sheet excellent in light transmittance, haze characteristics and various physical properties, and low in manufacturing cost.

The present invention relates to a transparent copolyester thick sheet sheet which is excellent in transparency and various physical properties, and is inexpensive to manufacture and can be usefully used as a substitute for a transparent soundproof wall, a high-rise building glass window, and the like.

More specifically, the present invention is made of a copolymer of dimethyl-2,6-naphthalene dicarboxylate (NDC), 1,4-cyclohexanedimethanol (CHDM), dimethyl terephthalate (DMT) and ethylene glycol (EG). The present invention relates to a transparent copolyester thick plate sheet having a light transmittance of 83% or more and a haze value of 5% or less.

The present invention provides dimethyl-2,6-naphthalene dicarboxylate (hereinafter referred to as NDC) and 1,4-cyclohexane to control the thermal and rheological properties requirements of polymers required for the formation of transparent copolyester thick sheet. It is characterized by introducing dimethanol (CHDM) as a monomer for copolymerization.

In order to manufacture a transparent thick sheet using a polymer material, the following basic properties are required.

First, since it is processed in the molten state, it is necessary to have a stability that the molecular chain is not easily broken in the molten state.

Second, it must have adequate melting characteristics. In other words, high melt viscosity is required to maintain the shape of the thick sheet in the molten state, but if it is too high, processing becomes difficult, and therefore high viscosity is required within the processable degree.

Third, the crystallization behavior should be appropriate. The thicker the sheet, the harder the rapid cooling. Therefore, in order to prevent crystal formation that degrades the transparency of the sheet, it is preferable that the crystallization rate is slow, and that the material itself has low crystallinity. However, a complete amorphous material may impede the improvement of mechanical strength, so crystallization within a range of physical properties is required.

As a material satisfying only a part of the above required characteristics, it is difficult to manufacture a thick sheet, it is desirable to satisfy all the possible characteristics.

Hereinafter, the present invention will be described in more detail.

The present invention prepares a copolyester resin by melt copolymerizing NCD, CHDM, DMT, and EG, and then extrudes it with an existing extrusion sheet molding machine to prepare a copolyester thick sheet. In the present invention, as the monomer for copolymerization, dimethyl-2,6-naphthalene dicarboxylate (NDC) of general formula (VI) and 1,4-cyclohexanedimethanol (CHDM) of general formula (V) are used simultaneously. .

NDC is mainly used to polycondensate with EG to make polyethylene naphthalate (hereinafter referred to as PEN) of general formula (VII), which is a highly functional polymer.

Such PEN shows very excellent properties in almost all physical properties, such as heat resistance, UV protection, gas barrier properties, tensile strength and hydrolysis resistance, compared to PET. However, NDC, which is a main raw material, is expensive and has difficulty in commercial production, and thus is used only in limited fields such as high-performance video tape films and special containers.

Therefore, recently, methods such as copolymerization and ball blending with PET have been introduced in order to secure a competitive price / performance ratio, but the scope of development is still limited.

However, in the present invention, NDC is used as a monomer for copolymerization for the purpose of controlling the thermal and rheological properties required for forming the transparent copolyester thick sheet, rather than the conventional purpose of improving the characteristics such as heat resistance and UV protection. do.

That is, NDC is used as a monomer for copolymerization in order to appropriately delay the crystallization rate for preparing the transparent thick sheet, to reduce the crystallinity of the resin, and to secure the melt viscosity necessary for maintaining the strength in the molten state for easy molding.

The present invention first melt copolymerized NCD, CHDM, DCT and EG to prepare a random copolyester resin of the general formula (VIII) having an intrinsic viscosity of 0.70 ~ 0.90 level.

In the melt copolymerization, the NDC content is preferably 8 mol% or less relative to the total monomers, but the NDC content is not particularly limited.

In general, however, the higher the NDC content, the lower the crystallinity of the resin itself. If the NDC content is too high to reduce the crystallinity of the resin itself, the obtained resin after melt polymerization may be subjected to solid phase polymerization again to adjust the intrinsic viscosity (IV) of the resin. In addition, the content of CHDM is preferably 15 mol% or less relative to the total monomers.

In the random copolyester resin structure of formula (VIII), the portion containing NDC instead of DMT and the portion containing CHDM instead of EG are longer, but the angle of the molecular chain is maintained, so the structure of formula (IV) Rather, it is similar to PETG, which is a product of Estman Chemical Company. As a result, the mechanism on the crystallization properties is similar to that of PETG, or more advantageous for thick sheet forming. This local nonuniformity of the molecular chain length acts as a hindrance to crystal formation requiring regularity, which slows down the crystallization rate and also lowers the crystallinity. In addition, while obtaining the same effect as the polymerization does not lower the reactivity during the polymerization, the polymerization is easy, PEN physical properties are added to the PET and PETG physical properties is further improved physical properties.

As a result, since the copolyester resin of the general formula (VIII) satisfies both the thermal and rheological properties of the resin required in the transparent thick sheet forming process, the transparent thick sheet can be easily formed using these resins.

Next, the copolyester resin of the general formula (VIII) is fed to an extrusion sheet molding machine, and these resins are melted and extruded to prepare a transparent copolyester thick sheet of the present invention.

The transparent copolyester thick sheet of the present invention is composed of a copolymer of NDC, CHDM, DMT, and EG, has a light transmittance of 83% or more, and a haze value of 5% or less.

In addition, the transparent copolyester thick sheet of the present invention has a crystallization calorific value (ΔHmc) of 1.0 J / g or less and a visible light refractive index of 1.35 to 1.70.

In addition, the transparent copolyester thick sheet of the present invention has a melt viscosity of 900-8,000 poise measured at a shear rate of 1,000 sec-1 at 270 ° C, and 100 sec at 270 ° C. Melt viscosity measured by shear rate of -1 is 1,700-30,000 poise.

Various physical properties of the transparent copolyester thick sheet described above are measured by the following method.

Haze value (%) and light transmittance (%)

After cutting a certain portion of the thick sheet is measured with a haze-meter (Haze-Meter, NDH-300A-Japan Electric Co., Ltd.).

[Crystalization Calorie (J / g)]

It is measured by dynamic run using a scanning differential calorimeter (DSC).

Visible light rate

Measured with Abbe refractometer.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited only to the following examples.

Example 1

3 mol% of NDC and 3 mol% of CHDM are added to the mixture of DMT and EG, followed by melt copolymerization to prepare a copolyester resin, followed by solid phase polymerization to give an intrinsic viscosity (IV) of 0.80.

The copolyester resin thus prepared is fed to an extrusion sheet molding machine, and then melted and extruded to prepare a transparent sheet having a thickness of 6 mm. The results of measuring various physical properties of the prepared transparent sheet are shown in Table 1.

Example 2

8 mol% CHDM was added to the mixture of DMT and EG, followed by melt copolymerization to prepare a copolyester resin having an intrinsic viscosity of 0.75.

The copolyester resin thus prepared is fed to an extrusion sheet molding machine, and then melted and extruded to prepare a transparent sheet having a thickness of 8 mm. The results of measuring various physical properties of the prepared transparent sheet are shown in Table 1.

Example 3

8 mol% of NDC and 15 mol% of CHDM are added to a mixture of DMT and EG, followed by melt copolymerization to prepare a copolyester resin having an intrinsic viscosity of 0.71.

The copolyester resin thus prepared is fed to an extrusion sheet molding machine, and then melted and extruded to prepare a transparent sheet having a thickness of 10 mm. The results of measuring various physical properties of the prepared transparent sheet are shown in Table 1.

TABLE 1

* In melt viscosity, X represents the case where the share rate is 1,000 sec ⁻¹ and Y represents the case where the share rate is 100 sec ⁻¹ .

The transparent copolyester thick sheet of the present invention has excellent light transparency and haze characteristics in spite of its thick thickness and is excellent in transparency. In addition, it is excellent in various physical properties such as mechanical properties, and manufacturing cost is also low. As a result, the transparent copolyester thick sheet of the present invention can be usefully used in many industrial fields such as transparent soundproof walls, glass windows of high-rise buildings, and alternatives to automobile glass windows.

In addition, since the transparent thick sheet of the present invention is molded from the random copolyester resin of the general formula (VIII), the following effects can be obtained.

First, it is possible to adjust the melt viscosity is easy to manufacture a thick sheet.

The present invention has a large change in melt viscosity according to the content of NDC and CHDM, and can be prepared copolyesters having a wide variety of characteristics because of the large range of NDC and CHDM content control. In particular, the width of the resin can be controlled in the molten state can be easily overcome the limitation of the moldable thickness.

As a result, a transparent thick sheet sheet having a thickness of about 10 mm, which is difficult to manufacture with a conventional polyester resin, can be easily produced.

Second, there is no other property deterioration in NDC and CHDM content increase.

NDC and CHDM are the same except that the benzene ring is changed to naphthalene ring and ethylene is changed to cyclohexane compared to DMT and EG, and thus does not have a bending structure like DMI. In fact, NDC and CHDM react well without any problem even when copolymerization of PET while changing its content from 0 to 100 mol%.

Third, it is easy to adjust the crystallization characteristics.

Since the copolyester of the present invention exhibits different crystallization characteristics depending on the content of NDC and CHDM, the crystallization rate and the heat of crystallization of the resin itself can be arbitrarily controlled by controlling the content of NDC and CHDM and the degree of polymerization. . As a result, it is easy to manufacture a transparent thick sheet of a desired thickness.

Fourth, it is economic.

In the case of using only CHDM as a copolymerization monomer, to prepare a thick sheet, the concentration of CHDM should be added to about 30 mol%, but the present invention uses NDC as a copolymerization monomer simultaneously with CHDM, thereby reducing the amount of CHDM. In other words. When using 5 mol% NDC, only 10 mol% of CHDM is sufficient. Therefore, it can be manufactured at low cost.

Fifth, the physical properties of the prepared sheet is excellent.

Various excellent physical properties of PEN are expressed to a considerable level, showing superior properties to copolyesters using only copolyester or CHDM of general formula (VI) as copolymerization monomers in weather resistance, mechanical properties and chemical properties.

Claims (7)

It is made of a copolymer of dimethyl-2,6-naphthalene dicarboxylate (NDC), 1,4-cyclohexanedimethanol (CHDM), dimethyl terephthalate (DMT) and ethylene glycol (EG), with a light transmittance of 83 A transparent copolyester thick sheet having a% or more and a Haze value of 5% or less. The transparent copolyester thick sheet according to claim 1, wherein the heat of crystallization (ΔHmc) of the copolyester is 1.0 J / g or less. The transparent copolyester thick sheet according to claim 1, wherein the melt viscosity of the copolyester measured at a shear rate of 100 sec-1 at 270 ° C is 1,700 to 30,000 poises. The transparent copolyester thick sheet according to claim 1, wherein a melt viscosity of the copolyester measured at a shear rate of 1,000 sec −1 at 270 ° C. is 900 to 8,000 poises. The transparent copolyester thick sheet according to claim 1, having a thickness of at least 3 mm. The transparent copolyester thick sheet according to claim 1, wherein the copolyester has a visible light refractive index of 1.35 to 1.70. The transparent copolyester thick sheet according to claim 1, wherein the dimethyl-2,6-naphthalene dicarboxylate (NDC) content is 8 mol% or less and the 1,4-cyclohexanedimethanol (CHDM) content is 15 mol% or less. .