KR100420595B1 - Saturated polyester for plastic containers with excellent heat-resistence and gas barrier properties and its manufacturing method - Google Patents

Abstract

The present invention relates to a saturated polyester for a plastic container widely used in various containers such as plastic bottles, plastic cups, and the like, and to a method of manufacturing the same, particularly to improve physical properties such as heat resistance and gas barrier properties, compared to conventional general-purpose products. It is.

The present invention is to prepare a polyester for a plastic container by the DMT method or TPA method, the reaction by adding a nano-sized spherical silica during the synthesis of the polyester through a polycondensation reaction through a transesterification reaction or esterification reaction In this way, by dispersing nano-sized silica particles in the polymer by the preparation as described above, not only the mechanical properties of the saturated polyester are improved, but also the heat resistance and gas barrier property are improved, and various containers for juice drinks, beer, green tea, rice beverage, etc. This can be useful.

Description

Saturated polyester for plastic containers with excellent heat-resistence and gas barrier properties and its manufacturing method}

The present invention relates to a saturated polyester for a plastic container widely used in various containers such as plastic bottles, plastic cups, etc., and particularly, a saturated polyester having nano-sized silica particles in a polymer chain to improve heat resistance and gas barrier properties. It relates to a manufacturing method.

Saturated polyester is a linear thermoplastic polymer having an ester bond in the main chain, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc., and has excellent dimensional stability, weather resistance, surface smoothness, and a transparent and glossy appearance. It is widely used as a molded article such as synthetic fibers, films, containers, and housings.

However, these saturated polyesters have poor heat resistance and gas barrier properties due to low glass transition temperature (Tg) and the permeability of some gases, and thus have problems in being used as containers for various juice drinks, beer, green tea, rice drinks, and the like.

As a method for solving the above problem, a polyethylene naphthalate (PEN) resin or a mixed polymer of polyethylene naphthalate and polyethylene terephthalate has been proposed and some commercially available. However, the polyethylene naphthalate resin is higher in price than the general polyethylene terephthalate, so it is economically inferior and has problems in recycling. As another method, as in Japanese Patent Laid-Open Publication No. 1997-290457, there is a method of improving the heat-resistance, transparency, and gas barrier properties by increasing the orientation crystallization by biaxial stretching during the molding of PET bottles. However, when making bottles by the above method, it is difficult to raise the degree of orientation crystallization by more than 40% as a whole, which is why it is not known to be used for beverages filled with high temperatures of 92 ° C. or higher. There is a problem falling.

An object of the present invention is to uniformly disperse the nano-sized silica particles in the polyester polymer to increase the orientation crystallinity to 40% or more to improve heat resistance and to improve gas barrier properties by the presence of silica particles in the polymer The present invention provides a novel saturated polyester for plastic container and its manufacturing method.

The present invention is a general saturated polyester obtained through a condensation polymerization reaction through a transesterification reaction or an esterification reaction, characterized in that it contains about 0.002% to 10% by weight of silica particles having an average particle diameter of 3 to 100nm. It relates to a saturated polyester and a method for producing the same.

Hereinafter, the present invention will be described in detail.

Saturated polyesters in the present invention are made from aromatic dicarboxylic acid or ester forming derivatives and ethylene glycol as the main starting material, but may comprise another third component. At this time, one or two or more kinds selected from isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, phthalic acid, adipic acid and sebacic acid may be used as the aromatic dicarboxylic acid component. In addition to phosphorus ethylene glycol, a small amount of propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like may be used.

The saturated polyester used in the present invention may include additives such as heat stabilizers, anti-broking agents, antioxidants, antistatic agents, ultraviolet absorbers and the like as necessary.

In the present invention, when the saturated polyester is synthesized using the starting materials as described above, nano-sized silica particles are added, wherein the nano-sized silica particles should be kept in the nano-sized state in the reactant.

In the present invention, the nano-sized silica particles are generally prepared by reacting sodium silicate (Na ₄ Si) with water to produce sodium silicate, and then passing through a cation exchange resin column to remove sodium oxide by adsorbing the cation exchange resin. Obtained by In the case of the silica particles obtained at this time, the particle size is in the range of approximately 0.5nm to 1.0nm to grow it can be obtained nano-silica particles of the desired size.

Nano-sized silica particles have good dispersibility in water, but the low boiling point of water tends to aggregate immediately when water evaporates, so they may be stored in high temperature liquids such as ethylene glycol or butanediol. Particularly, in the case of saturated polyester, by dispersing in ethylene glycol (EG) as a raw material, side reactions can be minimized when maintaining the dispersion and reacting. In addition, nano-sized silica particles may be used alone or in combination of two or more particles having different average particle diameters. The liquid used as a slurry solution may be used alone or in combination of two or more liquids. Do.

The nano-sized silica particles are preferably added in an amount of 0.002% by weight or more and 10% by weight or less, more preferably 0.005% by weight or more and 6% by weight or less, based on the polymer of the saturated polyester. If the input amount is less than 20 ppm, the effect of improving physical properties is insufficient, and when it is added more than 10% by weight, it is difficult to be uniformly dispersed in the polymer, and the transparency decreases due to particle aggregation. In the present invention, the average particle diameter of the silica particles is also suitable in the range of 3 to 100 nm, the transparency is very poor when the average particle diameter exceeds 100 nm, the dispersion is difficult and transparent due to the surface tension of the particles when less than 3 nm is used There are problems such as deterioration.

In the present invention, when adding the nano-sized particles, for example, it is also possible to add a phosphorus compound such as phosphoric acid, Tri Methyl Phosphate (TPM), Tri Ethy Phosphate (TEP), Tri Phenyl Phosphate (TPP), etc. In this case, the phosphorus compound may obtain an effect of improving the color of the resin. The addition amount of the phosphorus compound is preferably adjusted in consideration of the equivalence ratio with the metal ions, but is preferably added so that the phosphorus content is in the range of 0.01% by weight to 0.1% by weight based on the polymer.

As described above, in order to improve dispersibility of nano-sized silica particles, it is preferable to add the particles in a slurry state in which the particles are dispersed in water, ethylene glycol or butanediol, or a mixture of two or more thereof. It is preferably in the range of 3% to 30% by weight, more preferably in the range of 5% to 20% by weight based on the slurry. When the amount is less than 3% by weight, too much slurry is added to cause a lot of side reactions, and when the amount is more than 30% by weight, the dispersibility of the particles is deteriorated, and thus coarse particles are formed. The smaller it is, the better it is to make a slurry of low concentration, and the larger the particle size, the higher the concentration of particles in the slurry.

When the nano-sized silica particle slurry is added during the synthesis of the polyester, it is important that the addition method is such that the nano-sized particles do not aggregate. In the present invention, the molar ratio (E / T) of ethylene glycol (EG) and terephthalic acid (TPA) or dimethyl terephthalate (DMT) is preferably about 1.8 to 2.5 in the DMT method, and about 1.3 to 2.5 in the TPA method. In order to improve particle dispersibility, there is no particular limitation in the present invention, but in the case of DMT (Dimethylterephthalate) method, when a slurry is dispersed in water, a large problem occurs in the reaction, such as ethylene glycol (EG) or butanediol (BD). In the TPA (Terephthalic Acid) process, it is generally not a big problem in the reaction even if some water is contained in the slurry.However, in terms of particle dispersion, the TPA method is more effective than the DMT method. Acidity drops.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1

100 parts by weight of dimethyl terephthalate (DMT) and 64 parts by weight of ethylene glycol (EG) were added to the reactor while stirring and 0.03 parts by weight of antimony trioxide and 0.06 parts by weight of manganese acetate tetrahydrate were dispersed in 3 parts by weight of ethylene glycol and added to the reactor. Next, the mixture was heated to 130 ° C. to 230 ° C., and subjected to transesterification for 4 hours, thereby making BHT (B-1). An ethylene glycol slurry containing 10% by weight of silica particles having an average particle size of 50 nm was filtered through a filter having a size of 0.5 μm filtration pore to make slurry (S-1). When the temperature of (B-1) was about 235 ° C, 0.03 parts by weight of trimethyl phosphate (TMP) was diluted with 2 parts by weight of ethylene glycol, and then 20 parts by weight of the prepared (S-1) slurry was gradually added. The BHT was filtered through a filter having a 3 μm filtration hole, and heated to raise the temperature from 235 ° C. to 285 ° C. over 50 minutes, and then subjected to a polycondensation reaction for 3 hours to form a polymer having physical properties as shown in Table 1. It was then cut into chips (P-1-1). Subsequently, the chip (CHIP) was placed in a general solid state polymerizer to solidify the polymer to form a polymer having physical properties as shown in Table 1 (P-1-2). In addition, a 500 kPa heat resistant PET bottle (P-1-3) was prepared using a PET heat bottle blow machine using the (P-1-2) polymer.

Example 2

In Example 1, 1 part by weight of nanoparticle slurry (S-1) was added to 235 ° C. BHT, and condensation polymerization was carried out in the same manner as in Example 1.

Example 3

A slurry (S-1) was prepared in the same manner as in Example 1 except that silica particles having an average particle size of 15 nm were used instead of silica particles having an average particle size of 50 nm.

Example 4

The same procedure as in Example 1 was carried out except that 1 part by weight of the nanoparticle slurry (S-1) was charged to 235 ° C. BHT and subjected to condensation polymerization.

Example 5

100 parts by weight of terephthalic acid and 75 parts by weight of ethylene glycol were added to the reactor and heated with stirring to raise the temperature from 30 ° C. to 230 ° C., followed by an esterification reaction for 6 hours to produce BHT, followed by slurry 175 weight with a molar ratio of EG and TPA of 2.0. After adding the part over 2 hours, the reaction was carried out while maintaining the temperature at 230 ° C. for 1 hour 30 minutes. Thereafter, 175 parts by weight of the produced BHT was filtered through a filter having a 3.0 µm filtration hole, and was transferred to a condensation polymerization reactor. After the completion of the solution, 0.02% by weight of phosphoric acid was added on a polymer basis, and 0.015% by weight of antimony trioxide on a polymer basis was diluted and added to a small amount of ethylene glycol. In addition, 20 parts by weight of a slurry (S-2), which was prepared by preparing a 10 wt% slurry in ethylene glycol using a silica particle having an average particle size of 15 nm and filtered through a filter having a 0.5 μm pore size, was added to BHT at 230 ° C. . Subsequently, the BHT was heated to raise the temperature from 230 ° C. to 285 ° C. over 50 minutes, and then subjected to a condensation polymerization reaction for 3 hours to prepare a polymer having physical properties as shown in Table 1, and cut it into chips (P-5-). One). Subsequently, the chip (CHIP) was placed in a general solid state polymerizer to obtain a polymer having physical properties as shown in Table 1 (P-5-2). In addition, a 500 mm heat resistant PET bottle (P-5-3) was prepared using a PET heat bottle blower.

Example 6

Example 5 was carried out in the same manner as in Example 5, except that 1 part by weight of the nanoparticle slurry (S-2) was charged in 235 ° C. BHT and subjected to condensation polymerization.

Example 7

A slurry (S-2) was prepared in the same manner as in Example 5 except that silica particles having an average particle diameter of 3 nm were used instead of silica particles having an average particle diameter of 15 nm.

Example 8

In Example 7, the same procedure as in Example 7 was carried out except that 0.05 parts by weight of the nanoparticle slurry (S-2) was added to 235 ° C. BHT for condensation polymerization.

Example 9

Except that after the addition of 50 parts by weight of the slurry (S-2) made of silica particles having an average particle size of 100 nm instead of silica particles having an average particle size of 15 nm in 230 ℃ BHT and then subjected to a condensation polymerization reaction. It carried out similarly to 5.

Example 10

In Example 5, 0.05 parts by weight of the slurry (S-2) made of silica particles having an average particle size of 100 nm in place of silica particles having an average particle diameter of 15 nm was added to 235 ° C. BHT to carry out condensation polymerization. It carried out similarly.

Comparative Example 1

100 parts by weight of terephthalic acid and 75 parts by weight of ethylene glycol were added to the reactor and heated with stirring to raise the temperature to 230 ° C., followed by esterification for 6 hours to produce BHT. Then, 175 parts by weight of a slurry having a molar ratio of EG and TPA of 2.0 was 2 After the addition over time, the reaction was carried out while maintaining the temperature at 230 ℃ for 1 hour 30 minutes. Subsequently, 175 parts by weight of the produced BHT was filtered through a filter having a 3.0 μm filtration hole and transferred to a condensation polymerization reactor. After the completion of this solution, 0.02% by weight of phosphoric acid was added to the polymer, and 0.015% by weight of antimony trioxide was diluted and added to a small amount of ethylene glycol based on the polymer, followed by heating, followed by heating from 230 ° C to 285 ° C over 50 minutes. After raising the temperature, a polycondensation reaction was performed for 3 hours to prepare a polymer having physical properties as shown in Table 1, and cut it into chips (P-11-1). Subsequently, the chip was placed in a general solid state polymerizer to obtain a polymer having physical properties shown in Table 1 (P-11-2). Subsequently, 500cc heat-resistant PET bottle (P-11-3) was made using PET heat-resistant blower with the polymer (P-11-2).

Comparative Example 2

In Example 5, the same procedure as in Example 5 was carried out except that the slurry (S-2) was made of silica particles having an average particle size of 200 nm instead of the silica particles having an average particle size of 15 nm.

Comparative Example 3

Comparative Example 2 was carried out in the same manner as in Comparative Example 2 except that 1 part by weight of the slurry (S-2) made of silica particles having an average particle diameter of 200 nm was added to 235 ° C. BHT and subjected to condensation polymerization.

[Comparative Example 4]

Liquid phase polymerization was carried out in the same manner as in Example 5 except that 100 ppm of silica particles having an average particle diameter of 2 nm were contained, but the solid phase polymerization was carried out by the presence of foreign particles having a size of about 3 mm in the polymer. Did not do it.

The physical properties of the polymer and the heat-resistant PET bottle obtained in Examples and Comparative Examples were measured and shown in Table 1 below.

TABLE 1

TABLE 1

The heat resistance and O ₂ gas barrier properties measured in Table 1 were measured by the following method.

Heat resistance

The heat resistance temperature indicating heat resistance was measured as the initial heat resistance temperature by heating the water to a predetermined temperature and then filling the bottle instantaneously to measure the shape stability of the bottle.

O ₂ gas barrier properties

After the bottle was oxygen-blocked with epoxy, nitrogen was put into the bottle at a constant rate and at the same time flowed out at a constant rate, and the oxygen concentration contained in the nitrogen was measured to calculate the amount of passage through the outside of the bottle during the day.

As can be seen from the above examples and comparative examples, the saturated polyester according to the present invention is a PET bottle which is used as a container for beverages or various foods by improving the heat resistance and gas barrier properties of gases such as O _{2 due} to the presence of nano-sized silica particles. It may be usefully used as such.

Claims (7)

It is obtained by transcondensation polymerization and solid-state polymerization with aromatic dicarboxylic acid and ethylene glycol as main components, through transesterification or esterification, and is a general saturated polyester having an intrinsic viscosity in the range of 0.70 to 0.90 and an ester bond in the main chain. The saturated polyester for plastic containers in which the average particle diameter contains the silica particle in the range of 3-100 nm size in 0.002 weight% or more and 10 weight% or less on a polymer basis. The saturated polyester for plastic container according to claim 1, wherein the saturated polyester is polyethylene terephthalate. 2. The plastic container according to claim 1, wherein the silica particles are prepared by growing silica particles obtained by reacting sodium silicate with water to produce sodium silicate, and then passing through a cation exchange resin column to remove sodium oxide. Saturated polyester. Aromatic dicarboxylic acid and ethylene glycol are the main components, which are obtained through transesterification and solidification polymerization through transesterification or esterification, and have an intrinsic viscosity of 0.70 to 0.90. A method for producing a saturated polyester for plastic containers, wherein silica particles of ˜100 nm are added during the synthesis reaction. The method for producing saturated polyester for plastic containers according to claim 4, wherein the silica particles are made into a slurry solution containing 3 to 30% by weight of silica particles. 6. The method of claim 5 wherein the solvent used in the slurry solution is ethylene glycol. The method according to claim 4, wherein the silica particles are added in a range of 0.002% by weight to 10% by weight based on the polymer.