KR20080054575A - Copolyester resin and articles using the same - Google Patents

Abstract

A copolyester resin is provided to improve the heat shrinking property at low temperature, and to reduce the cycle time and to improve the moldability during a molding process using a heat shrinking label. A copolyester resin comprises: a dicarboxylic acid component including terephthalic acid; and a diol component containing 10-80 mol% of 1,4-cyclohexanedimethanol, 0.1-30 mol% of a bisphenol A derivative represented by the following formula 1, and the balance amount of ethylene glycol based on 100 mol% of the total weight of the diol component. In formula 1, each of x and y is an integer of 2-5; and m + n is an integer of 6-20.

Description

Copolyester resin and molded products using same {Copolyester resin and articles using the same}

The present invention relates to a copolyester resin and a molded article using the same. More specifically, the present invention relates to a copolymer polyester resin and a molded article using the same, which exhibits an effect of shortening the cycle time and improving the moldability of a product during molding processing using a heat shrink label.

Heat shrinkable plastic products are widely used in film applications such as shrink wrap, shrink labels, etc. due to their shrinking properties upon heating. Among them, polyvinyl chloride (PVC), polystyrene, polyester plastic film, and the like have been used for the purpose of labeling, cap seal, or direct packaging of various containers.

However, films made of polyvinyl chloride are environmentally regulated, such as hydrogen chloride gas and substances causing dioxins during incineration. In addition, if this product is used as a shrink label for a PET container, there is a hassle to separate the label from the container when the container is recycled.

In addition, the polystyrene-based film has a good work stability according to the shrinkage process and the appearance of the product is good, but the chemical resistance is not good, the ink of a special composition must be used when printing. In addition, there is a disadvantage that the dimensions are deformed, such as shrinkage by itself due to lack of storage stability at room temperature.

Films made of polyester resins without these problems are expected to be considerably shrinkable labels, replacing films made from the two raw materials. Moreover, as the usage of PET containers increases, the usage of polyester films that can be easily recycled without separate labels during recycling increases.

However, conventional heat-shrinkable polyester films require new improvements in shrinkage properties. In particular, due to a sudden change in shrinkage behavior, a problem frequently arises during molding, which is different from the intended design due to wrinkles or uneven shrinkage during shrinkage. In addition, when compared with a polyvinyl chloride-based film or a polystyrene-based film, the shrinkage property at a low temperature is inferior, and thus must be shrunk at a high temperature to compensate for this. In this case, there is a problem that deformation or cloudiness of the PET container occurs.

In order to solve the above problems, the present inventors have studied and studied to prepare a polyester resin having a heat shrinkage property superior to the copolymerized polyester resin according to the prior art, as a result, 1,4-cyclohexanedimethanol copolymerized poly By replacing some of the diol components of the ester resin with aromatic diols of bisphenol-A derivatives, the shrinkage characteristics at low temperatures could be improved, and the present invention was completed based on this.

Accordingly, an aspect of the present invention is to provide a copolymer polyester resin having excellent heat shrinkage characteristics at a low temperature and a molded article using the same.

Another aspect of the present invention is to provide a copolymer polyester resin and a molded article using the same, which can shorten a cycle time and improve moldability of a product during molding processing using a heat shrink label.

Co-polyester resin according to a preferred embodiment of the present invention,

Dicarboxylic acid components including terephthalic acid; And

10 to 80 mol% of 1,4-cyclohexanedimethanol, 0.1 to 30 mol% of the bisphenol-A derivative represented by the following formula (1) and the total diol component so that the total is 100 mol% of the remaining diol component containing ethylene glycol ;

Characterized in that it comprises:

Wherein x and y are each an integer of 2-5, and m + n is an integer of 6-20.

Preferably, the bisphenol-A derivative is polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2,0) -2,2-bis (4 -Hydroxyphenyl) propane, polyoxypropylene- (2,2) -polyoxyethylene- (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,3) -2,2- Bis (4-hydroxyphenyl) propane, polyoxypropylene- (3,3) -3,3-bis (4-hydroxyphenyl) propane, polyoxyethylene- (3,0) -2,2-bis ( 4-hydroxyphenyl) propane, polyoxyethylene- (6) -2,2-bis (4-hydroxyphenyl) propane and mixtures thereof.

More preferably, the bisphenol-A derivative is polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane represented by the following formula (2):

Wherein q + r is an integer from 6 to 15.

The molded article according to one preferred embodiment of the present invention is obtained by extruding or injection molding the copolyester resin of the present invention described above.

Preferably, the molded article is a heat shrink film, has a shrinkage onset temperature of 70 ° C. or lower, and a maximum heat shrinkage at 70 ° C. of 2% or more.

More preferably, the molded article has a maximum heat shrinkage of at least 50% at 85 ° C.

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

As described above, in the present invention, a film capable of heat shrinking at low temperature is manufactured by partially replacing the diol using an aromatic diol which is a bisphenol-A derivative when preparing a polyester resin copolymerized with 1,4-cyclohexanedimethanol. Provided is a copolyester resin having excellent moldability and a molded product using the same.

Copolyester resin according to the present invention is prepared through the first step of the esterification reaction and the second step of the polycondensation reaction.

The first step, the esterification reaction may be carried out in a batch or continuous manner, and each raw material may be added separately, but it is most preferable to make a dicarboxylic acid component into a diol component in a slurry form. .

More specifically, first, a dicarboxylic acid containing terephthalic acid is reacted with a diol component containing 1,4-cyclohexanedimethanol, a bisphenol-A derivative, and ethylene glycol.

In this case, it is preferable to add the diol component so that the content of the diol component is 1.2 to 3.0 in a molar ratio, and to perform the esterification under the conditions of 230 to 260 ° C and 1.0 to 3.0 kg / cm 2, but not limited thereto. It doesn't happen. Preferably, the said esterification temperature is 240-260 degreeC, More preferably, it is 245-255 degreeC. In addition, the esterification time is usually about 100 to 300 minutes, which may be appropriately changed depending on the reaction temperature, pressure, and the molar ratio of the diol component to the dicarboxylic acid component used.

The 1,4-cyclohexanedimethanol is usually used to improve the moldability or other physical properties of the homopolymer based only on the terephthalic acid and ethylene glycol. The 1,4-cyclohexanedimethanol used in the present invention includes cis-, trans-, or a mixture of two isomers, and the amount of the 1,4-cyclohexanedimethanol is 10 to 80 of the total diol components in order to prevent moldability due to crystallization. It is good to be mol%.

The aromatic diol which is a bisphenol-A derivative used in the present invention is represented by the following general formula (1), and is used to improve low temperature shrinkage.

Formula 1

Wherein x and y are each an integer of 2-5, and m + n is an integer of 6-20.

The amount of the bisphenol-A derivative is preferably 0.1 to 30 mol% of the total diol components. If the amount is less than 0.1 mol%, it is difficult to confirm the effect of improving the physical properties according to the addition of the bisphenol-A derivative, and 30 mol% If it exceeds, there is a problem that the utilization as a heat shrink film is reduced due to excessive heat resistance reduction.

As the bisphenol-A derivative, it is preferable to use a product having a purity of at least 85% by weight of the total weight of the bisphenol-A, including a compound having an added mole number (m + n) of 6 or more. When using a product having a purity of less than 85% by weight of a compound having an addition molar number (m + n) of 6 or more contained in the total bisphenol-A, the degree of Tg of the synthesized copolymerized polyester resin may be low. have.

Examples of the bisphenol-A derivatives include polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane and polyoxypropylene- (2,0) -2,2-bis (4-hydroxy Phenyl) propane, polyoxypropylene- (2,2) -polyoxyethylene- (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2,3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,3) -2,2-bis (4 -Hydroxyphenyl) propane, polyoxypropylene- (3,3) -3,3-bis (4-hydroxyphenyl) propane, polyoxyethylene- (3,0) -2,2-bis (4-hydroxy Oxyphenyl) propane, polyoxyethylene- (6) -2,2-bis (4-hydroxyphenyl) propane, and the like can be exemplified, and can be used alone or in combination of two or more thereof.

More preferably, the bisphenol-A derivative is polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane represented by the following formula (2):

Formula 2

Wherein q + r is an integer from 6 to 15.

As such, by using the bisphenol-A derivative, the shrinkage start temperature of the heat shrinkable film may be lowered, thereby shortening the cycle time when passing through the steam process, thereby increasing productivity. In addition, since the shrinkage rate is low during low temperature shrinkage, smooth process control is possible, thereby obtaining excellent results of reducing a defective rate.

On the other hand, the amount of ethylene glycol used as one of the diol components of the present invention is added so that the sum of all diol components is 100 mol% in consideration of the amount of 1,4-cyclohexanedimethanol and the bisphenol-A derivative.

Other diol components that can be used include 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 1, 2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and the like.

The esterification reaction does not require a catalyst, but may be optionally added to reduce the reaction time.

After the first step of the above-mentioned esterification reaction is completed, the second step of the polycondensation reaction is carried out, the polycondensation catalyst, stabilizer and colorant are selected as the components generally used in the polycondensation reaction of the polyester resin Can be used as

Polycondensation catalysts usable in the present invention include, but are not limited to, titanium, germanium and antimony compounds.

The titanium-based catalyst is generally used as a polycondensation catalyst of a polyester resin copolymerized with 1,4-cyclohexanedimethanol by 15% or more by weight of terephthalic acid, and even when a small amount is used in comparison with an antimony-based catalyst It is possible and also has the advantage of lower cost than germanium-based catalyst.

Titanium-based catalysts usable in the present invention include tetraethyl titanate, acetyltripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetrabutyl titanate, polybutyl titanate, 2-ethylhexyl titanate, octylene Glycol titanate, lactate titanate, triethanolamine titanate, acetylacetonate titanate, ethyl acetoacetic ester titanate, isostearyl titanate, titanium dioxide, titanium dioxide and silicon dioxide co-precipitates, titanium dioxide and zirconium dioxide And coprecipitates.

In this case, since the amount of the polycondensation catalyst affects the color of the final polymer, the amount of polycondensation catalyst may vary depending on the desired color and the stabilizer and colorant used. Preferably, the amount of polycondensation catalyst is 1 to 100 ppm based on the amount of titanium based on the weight of the final polymer. More preferably, 1-50 ppm is good and 10 ppm or less is preferable based on a silicon element amount.

In addition, stabilizers and coloring agents and the like can be used as other additives.

Stabilizers usable in the present invention typically include phosphoric acid, trimethyl phosphate, triethyl phosphate, triethyl phosphonoacetate, and the like, and the amount of the stabilizer may be 10 to 100 ppm relative to the weight of the final polymer based on the small amount of people.

In addition, the colorants usable in order to improve the color in the present invention include conventional colorants such as cobalt acetate and cobalt propionate, the addition amount is preferably 0 to 100ppm relative to the final polymer weight.

In addition to the colorant, conventionally known organic compounds may be used as the colorant.

On the other hand, the second condensation reaction is carried out after the addition of these components is preferably carried out under reduced pressure conditions of 260 ~ 290 ℃ and 400 ~ 0.1mmHg, but is not limited thereto.

The polycondensation step is carried out for the required time until the desired intrinsic viscosity is reached, the reaction temperature is generally 260 ~ 290 ° C, preferably 260 ~ 280 ° C, more preferably 265 ~ 275 ° C.

In addition, polycondensation reaction is performed under reduced pressure of 400-0.1 mmHg in order to remove the diol component which arises as a by-product, and the polyester resin copolymerized with 1, 4- cyclohexane dimethanol is obtained.

As described above, the copolyester resin according to the present invention has a low shrinkage start temperature, so the shrinkage rate is low, so that smooth process control is possible, thereby having excellent moldability to reduce the defective rate. Therefore, such a copolyester resin may be molded through an extrusion / injection and stretching process to obtain a molded product such as a heat shrinkable film having excellent moldability.

That is, the molded article obtained therefrom preferably has a shrinkage initiation temperature of 70 ° C. or lower and 40 ° C. or higher, and a maximum heat shrinkage of 70% or less and 50% or 50% or a maximum heat shrinkage of 85% or higher. By lowering the shrinkage onset temperature to less than 100%, heat shrinkage is possible at a low temperature similar to PVC, which can prevent the deformation or turbidity of the PET container caused by the heat shrinkage process of the film, and control the shrinkage rate. Ease results in reducing mold defects.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited thereto.

The physical properties shown in the following Examples and Comparative Examples were measured in the following manner:

◎ Glass Transition Temperature (Tg): Using Differential Scanning Calorimetry from TA Instrument

◎ Heat shrinkage rate: Cut into 10cm × 10cm square, immerse for 10 seconds under no load in hot water at the temperature as listed in Table 1, heat shrink and then immerse in water for 25 seconds for 10 seconds Measure the longitudinal and transverse lengths according to the following formula.

Heat shrinkage rate (%) = 100 * (length before contraction-length after contraction) / (length before contraction)

◎ Melt resistivity (Ω · cm): A pair of electrode plates is inserted into a chip or film melted at 275 ° C., and a voltage of 120 V is applied. The current at that time is measured, and the melt specific resistance Si (Ω · cm) based on the following formula is calculated.

Si = (A / I) × (V / io)

Where A is the area of the electrode (cm 2), I is the distance between the electrodes (cm), V is the voltage (V), and io is the current (A).

When the copolyester is prepared using such a device, the following results can be obtained.

Example 1

173 g of 1,4-cyclohexanedimethanol, 521 g of ethylene glycol, polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane (addition mole number = 6) based on 6 moles of terephthalic acid The 78g copolymerized polyester resin was reacted in a 3L reactor equipped with a stirrer and an outflow condenser while gradually raising the temperature to 255 ° C.

At this time, the generated water is discharged out of the system to ester reaction, and when the generation of water, the outflow is finished, the contents are transferred to a polycondensation reactor equipped with a stirrer, a cooling condenser and a vacuum system.

Add 0.5 g of tetrabutyl titanate to the esterification reaction, add 0.4 g of triethylphosphate, add 0.5 g of cobalt acetate, and increase the internal pressure from 240 ° C to 275 ° C. After 40 minutes of low vacuum reaction from atmospheric pressure to 50mmHg, ethylene glycol was removed, and then gradually decompressed to 0.1mmHg until the desired intrinsic viscosity under high vacuum was discharged and cut into chips.

The heat shrink film prepared using the 1,4-cyclohexanedimethanol copolymer polyester resin thus prepared was measured by the above-described method to measure the glass transition temperature, shrinkage start temperature, heat shrinkage rate, and melt resistivity value. Table 1 shows.

Example 2

Except for adding 390 g of polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane was prepared in the same manner as in Example 1, the glass transition temperature, shrinkage measured therefrom Initiation temperature, heat shrinkage and melt resistivity are shown in Table 1 below.

Comparative Example 1

It was prepared in the same manner as in Example 1 except that polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane was not added, and the glass transition temperature and shrinkage measured therefrom were measured. Initiation temperature, heat shrinkage and melt resistivity are shown in Table 1 below.

Comparative Example 2

Prepared in the same manner as in Example 1, except that 80 g of a monomer having a main component of less than 6 moles of polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane was added. The glass transition temperature, shrinkage start temperature, heat shrinkage rate, and melt resistivity measured therefrom are shown in Table 1 below.

Comparative Example 3

A heat shrink film was prepared using a PVC resin, and the glass ion ions measured therefrom, shrinkage start temperature, heat shrinkage rate, and melt resistivity value are shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Glass transition temperature (Tg, ℃) 70 59 80 79 65 Shrink start temperature (℃) 59 45 71 71 50 Heat shrinkage (at 60 ℃) 4% 6% 0% 0% 5% Heat shrinkage (at 85 ℃) 80% 79% 79% 78% 65% Melt Resistivity (× 10 ⁸ Ω · cm) 0.15 0.14 0.12 0.13 0.16

Although the present invention has been described in detail through specific examples, this is for explaining the present invention in detail, and the copolymerized polyester resin and the molded article using the same according to the present invention are not limited thereto, and the technical spirit of the present invention is limited thereto. It is apparent that modifications and improvements are possible by those skilled in the art.

As can be seen from the examples and comparative examples, in the present invention, by shrinking the start temperature of the shrinkage of the polyester resin copolymerized using a specific bisphenol-A derivative, it is possible to heat shrink at a low temperature similar to PVC, This can prevent the deformation or turbidity of the PET container caused in the heat shrink process of the film, it is possible to achieve the result of reducing the molding failure due to the easy control of the shrinkage rate.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

Claims (7)

Dicarboxylic acid components including terephthalic acid; And 10 to 80 mol% of 1,4-cyclohexanedimethanol, 0.1 to 30 mol% of the bisphenol-A derivative represented by the following formula (1) and the total diol component so that the total is 100 mol% of the remaining diol component containing ethylene glycol ; Copolymerized polyester resin comprising: Formula 1

Wherein x and y are each an integer from 2 to 5, and m + n is an integer from 6 to 20. The method of claim 1, wherein the bisphenol-A derivative is selected from polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (2,2) -polyoxyethylene- (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (2, 3) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (6) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxypropylene- (3,3) -3,3-bis (4-hydroxyphenyl) propane, polyoxyethylene- (3,0) -2,2- Co-polyester resin, characterized in that it is selected from the group consisting of bis (4-hydroxyphenyl) propane, polyoxyethylene-(6) -2, 2-bis (4-hydroxyphenyl) propane and mixtures thereof. The copolyester resin according to claim 1, wherein the bisphenol-A derivative is polyoxyethylene- (2,3) -2,2-bis (4-hydroxyphenyl) propane represented by the following formula (2): : Formula 2

Wherein q + r is an integer from 6 to 15. A molded article obtained by extruding or injection molding the copolyester resin according to any one of claims 1 to 3. The molded article of claim 4, wherein the molded article is a heat shrinkable film. The molded article of claim 4, wherein the molded article has a shrinkage onset temperature of 70 ° C. or lower, and a maximum heat shrinkage at 70 ° C. is 2% or more. The molded article of claim 4, wherein the molded article has a maximum heat shrinkage at 50 ° C. of 50% or more.