KR20080056470A - Heat-shrink film using blending of polyethylene terephthalate resin and transparent copolyester resin - Google Patents

Abstract

The present invention relates to a heat shrinkable film using a blend of a polyethylene terephthalate resin and a transparent copolyester resin, and more particularly, to a polyethylene terephthalate resin having an intrinsic viscosity of 0.50 to 1.2 dl / g, and a dicarboxylic acid. It relates to a heat shrink film produced by blending a transparent copolyester resin copolymerized with 50 to 80 mol% of 1,4-cyclohexanedimethanol.

According to the present invention, it is possible to control the shrinkage rate by controlling the content of 1,4-cyclohexanedimethanol as desired without a separate polymerization process, and to dry the polyethylene terephthalate resin and the transparent co-polyester resin in one place. This improves workability by simplifying work steps, resulting in cost savings and improved production efficiency.

Description

The thermal shrinkable film made from blending of polyethyleneterephthalate and co-polymerized polyester}

The present invention relates to a heat shrinkable film using a blend of a polyethylene terephthalate (hereinafter 'PET') resin and a transparent co-polyester resin, and more particularly, to a polyethylene terephthalate resin having an intrinsic viscosity of 0.50 to 1.2 dl / g. And heat shrink film produced by blending a transparent copolyester resin in which 50 to 80 mol% of 1,4-cyclohexanedimethanol is copolymerized with respect to the dicarboxylic acid component.

Heat shrinkable plastic products utilize the property of shrinking with heating and are widely used for film applications such as shrink wrap, shrink labels, and the like. Among them, polyvinyl chloride (PVC), polystyrene, polyester-based plastic film, and the like have been used for the purpose of labels, cap seals, 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 the product is used as a shrink label for PET containers, there is a hassle to separate the label from the container when the container is recycled.

In addition, the polystyrene-based film has good work stability according to the shrinkage process, the appearance of the product is good, but the chemical resistance is not good, and when printing, the ink of a special composition must be used. 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 such a problem are expected to be a shrinkage label, replacing films made of the two raw materials. In addition, as the amount of the container made of polyethylene terephthalate resin (hereinafter referred to as 'PET resin') increases, the amount of polyester film that can be easily recycled without separating a label during recycling increases. However, conventional heat-shrinkable polyester films require new improvements in shrinkage properties. In particular, the shrinkage may be different from the intended pattern due to wrinkles or non-uniform shrinkage during shrinkage, and when compared with polyvinyl chloride or polystyrene films, shrinkage at low temperatures is inferior. It must shrink at high temperatures, and in this case, deformation or turbidity of the PET container often occurs.

In order to solve this problem, conventionally reported technical data is known a method for producing a heat shrinkable film using a blended product of 1,4-cyclohexanedimethanol copolymerized transparent polyester resin and PET resin. In addition, by easily adjusting the content of 1,4-cyclohexanedimethanol in the product without a separate polymerization process, it is possible to obtain the advantage that the shrinkage rate of the heat shrinkable film using the resin can be changed according to the application. However, the commonly used transparent polyester resin is a resin which is widely commercialized by copolymerizing 1,4-cyclohexanedimethanol to about 30 mol% of terephthalic acid, and may cause problems such as fusion of transparent polyester resin in a drying process. Work must be done below the glass transition temperature. Therefore, there is a disadvantage in that the PET resin must be dried through a separate process, and it must be dried for a long time because it is dried at a low temperature.

Meanwhile, US Pat. No. 4,874,809 solves the problem of PET resin turbidity by blending 100% by mol of a transparent polyester resin copolymerized with terephthalic acid to PET resin and 1,4-cyclohexanedimethanol. However, in this case, as the content of the transparent polyester resin increases, the processing temperature increases during blending, so that pyrolysis occurs, and thus, the physical properties decrease and the color changes to yellow, so that the blending operation is smooth without adding a separate heat stabilizer. A disadvantage arises that is not made.

The present inventors have solved the problems of the prior art as described above, and researched to produce a polyester heat shrinkable film having properties superior to conventional polyester resins, a transparent polyester resin and a PET resin having specific properties By blending to a specific composition ratio, the content of 1,4-cyclohexanedimethanol can be easily adjusted as desired, and eventually developed an economical and efficient method to easily produce the desired shrinkage ratio for each application, The present invention has been completed based on this.

Accordingly, an object of the present invention is to provide a heat shrink film using a blend of a PET resin and a transparent co-polyester resin, which overcomes the drawbacks of each of the transparent polyester resin and the PET resin and has excellent physical properties.

Another object of the present invention is to control the content of 1,4-cyclohexanedimethanol as desired without a separate polymerization process, PET resin and transparent that can be dried through a single process together with a PET resin and a transparent co-polyester resin It is to provide a method for producing a copolyester resin blend.

According to the present invention for achieving the above and other objects, the heat shrink film,

1 to 99 mol% of a polyethylene terephthalate (PET) resin having an intrinsic viscosity of 0.50 to 1.2 dl / g; And

A diol component having a content of 50 to 80 mol% of 1,4-cyclohexanedimethanol in the transparent co-polyester resin and including one or more diols except for the 1,4-cyclohexanedimethanol; 1 to 99 mol% of a transparent copolyester resin prepared by condensing an acid component;

5 to 60 mol% of the 1,4-cyclohexanedimethanol based on the dicarboxylic acid component in the total blended polyester resin is included.

Method for producing a heat shrinkable film composition according to the present invention for achieving another object of the present invention,

Polyethylene terephthalate resin having intrinsic viscosity of 0.50 to 1.2 dl / g of 1 to 99 mol% of transparent copolyester resin copolymerized with 50 to 80 mol% of 1,4-cyclohexanedimethanol based on the dicarboxylic acid component Mixing 1 to 99 mole% to include 5 to 60 mole% of the 1,4-cyclohexanedimethanol based on the dicarboxylic acid component in the blended total polyester resin; And drying the mixture at a temperature of 120 to 160 ° C.

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

As described above, the heat shrinkable film according to the present invention comprises 1 to 99 mol% of polyethylene terephthalate (PET) resin having an intrinsic viscosity of 0.50 to 1.2 dl / g; And a diol component having a content of 1 to 4-cyclohexanedimethanol in the transparent co-polyester resin and containing one or more diols except for the 1,4-cyclohexanedimethanol, 1 to 99 mol% of a transparent copolyester resin prepared by condensing a carboxylic acid component;

5 to 60 mol% of the 1,4-cyclohexanedimethanol based on the dicarboxylic acid component in the total blended polyester resin is included.

According to the present invention, in the manufacture of a polyester heat shrink film, the compatibility with PET resin to have a heat shrinkage rate suitable for each use, and to be dried in the same process as the PET resin to form a crystal 1, Provided is a blend of a PET resin and a transparent copolymerized polyester resin blended through an economical and efficient process by blending a polyester resin copolymerized by controlling the amount of 4-cyclohexanedimethol monomer with the PET resin, and a method of manufacturing the same.

In general, polyester resins copolymerized with 1,4-cyclohexanedimethanol are known to prevent crystallization from occurring by interfering regularity between structures in PET resin.

However, in the present invention, when the 1,4-cyclohexanedimethanol monomer is added in a predetermined amount or more, it has structural regularity by itself, and thus crystallization is also performed in the polyester resin copolymerized with 1,4-cyclohexanedimethanol. On the basis of the discovery that is formed, when the copolymerized polyester resin is crystallized and then blended with the PET resin, it is possible to dry at once without unnecessary two-step drying process, thereby easily preparing a blending resin. Confirmed that it can.

Specifically, the blend according to the present invention is a transparent copolymer poly copolymerized with PET resin having an intrinsic viscosity of 0.50 to 1.2 dl / g and 50 to 80 mol% of 1,4-cyclohexanedimethanol based on the dicarboxylic acid component. By blending the ester resin.

PET resin used in the present invention is preferably intrinsic viscosity is 0.50 ~ 1.2dl / g, preferably 0.75 ~ 0.87dl / g. At this time, when the intrinsic viscosity of the PET resin is less than 0.50dl / g is expected to lower the mechanical properties due to the low molecular weight, when it exceeds 1.2dl / g, high pressure and temperature are required for blending and molding efficiency of Degradation occurs.

The PET resin is usually polymerized from dicarboxylic acids and diols, as known in the art. Dicarboxylic acids and derivatives thereof used in the polymerization of the PET resin are mainly terephthalic acid (TPA), isophthalic acid (IPA), naphthalene 2,6-dicarboxylic acid (2,6-naphthalenedicarboxylic acid; 2, 6-NDA), dimethylterephthalic acid (DMT), dimethylisophthalate (DMI), dimethyl naphthalene 2,6-dicarboxylic acid (dimethyl 2,6-naphthalenedicarboxylate; 2,6-NDC), but are not limited thereto. It doesn't become

In addition, the diol used in the polymerization of the PET resin is EG, diethylene glycol (DEG), propylene glycol (PG), neopentyl glycol (NPG), cyclohexane dimethanol (cyclohexane dimethanol; CHDM) is not particularly limited, and all diols known in the art may be used in the manufacture of PET resin, but EG is preferable.

Looking at the polymerization process of the PET resin in more detail, the raw material dicarboxylic acid and diol are introduced into a reactor of a high temperature and high pressure, by adding a reaction catalyst, stabilizer and colorant as necessary to the oligomer (oligomer) made here The reaction is carried out in a high temperature vacuum state to polymerize a high molecular weight polyester resin, and the present invention is not particularly limited, and it is possible to polymerize a PET resin as known in the art.

The transparent copolyester resin copolymerized with 1,4-cyclohexanedimethanol used in the present invention has a content of 1,4-cyclohexanedimethanol monomer in the polyester resin so that a crystal phase can be formed when measured with a differential scanning calorimeter. It is preferable to adjust the amount to 50 to 80 mol% compared to the dicarboxylic acid component, and when the monomer content is less than 50 mol%, there is a problem in that a crystal form is not generated. Due to this pyrolysis occurs, the transparency of the product is lowered, the color is unexpectedly yellow, such as undesirable.

The transparent copolyester resin 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 separately added, but it is most preferable to add terephthalic acid in the form of a slurry to glycol.

More specifically, first, a dicarboxylic acid component containing terephthalic acid and a glycol component containing 1,4-cyclohexanedimethanol are reacted. 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.

1,4-cyclohexanedimethanol is used as another diol component other than ethylene glycol in order to improve the moldability or other physical properties of the homopolymer based only on terephthalic acid and ethylene glycol. As the 1,4-cyclohexanedimethanol, cis-, trans- or a mixture of the two isomers can be used, and the amount thereof is calculated to have a desired CHDM content in the final product blended with PET. It is preferably added in an amount similar to that of 50 to 80 mol% with respect to the dicarboxylic acid so that it can be dried together with the PET resin and, as described above, does not cause thermal decomposition due to high temperatures during processing. .

In addition, the amount of ethylene glycol used as one of the diol components is added to 100 mol% of the total diol components compared to the dicarboxylic acid in consideration of the amount of 1,4-cyclohexanedimethanol.

In addition, other diol components usable in the copolymerization of the copolymerized polyester resin 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, but are not particularly limited thereto. no.

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 generally used in the polycondensation reaction of the polyester resin. It may optionally be used as disclosed in.

Examples of the polycondensation catalyst usable in the present invention include titanium, germanium and antimony compounds, but are not particularly limited thereto.

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 copolyester, the amount of polycondensation catalyst may vary depending on the desired color, the stabilizer and the colorant used. 100 ppm, More preferably, 1-50 ppm is good and 10 ppm or less is preferable based on a silicon element amount. At this time, if the amount of titanium element is less than 1ppm can not reach the desired degree of polymerization, if it exceeds 100ppm the color of the final polymer is yellow and the desired color cannot be obtained.

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. At this time, if the addition amount of the stabilizer is less than 10ppm it is difficult to obtain the desired bright color, if it exceeds 100ppm there is a problem that does not reach the desired high polymerization degree.

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 glycol by-product, and the polyester resin copolymerized with 1, 4- cyclohexane dimethanol is obtained.

On the other hand, when blending the PET resin and the transparent co-polyester resin prepared as described above, each amount is used in 1 to 99 mol%, each of the 1,4-cyclohexanedimethanol monomer in the polymer after blending The mixing ratio can be adjusted in various ways to adjust the content as desired, but preferably the content of 1,4-cyclohexanedimethanol monomer in the total blend is 5 mol% or more and 60 mol% or less with respect to the dicarboxylic acid component. By adjusting the mixing ratio can be overcome the disadvantages of PET resin. In general, as the content of 1,4-cyclohexanedimethanol increases, the maximum heat shrinkage rate increases, but when 60 mol%, the high heat shrinkage rate and the increase of the shrinkage stress may damage the bottle product. Therefore, the commercially available range is usually 5 mol% or more and 60 mol% or less.

On the other hand, according to the existing method, the PET resin chip and the transparent polyester resin chip may be used directly by mixing the PET resin chip and the transparent polyester resin chip at the mixing ratio set during the blending process of the PET resin and the transparent co-polyester resin, but the drying temperature is a PET resin and the transparent poly Since the ester resins are different, the chips of each polymer must be dried separately.

However, in the present invention, since the two polymers are formed with specific properties and components as described above so that crystallization occurs in both polymers, the two chips are mixed in advance at a predetermined mixing ratio without being subjected to a separate two-step drying process. This is done by drying.

Here, the drying process is most preferably carried out at 120 to 160 ℃ in terms of economic efficiency compared to the efficiency. If the drying temperature is below 120 ° C, there is a disadvantage in that the drying efficiency is lowered. If the drying temperature is higher than 160 ° C, the crystal phase melts and there is a risk of fusion.

In general, when blending with a transparent copolyester resin containing 1,4-cyclohexanedimethanol monomer more than a certain amount, for example, about 30 mol%, of terephthalic acid, the injection molding machine may The temperature of the front zone (Feeding zone) should be lowered, and therefore, the temperature of the rear zone (Rear zone) should be set relatively high. It may have a processing temperature range.

The blend of the PET resin of the present invention prepared as described above and the copolyester resin may be molded through a conventional molding process known in the art, and may be manufactured into a molded article having a suitable shape as needed.

The heat shrinkage rates shown in the following Examples and Comparative Examples were compared by measuring the heat shrinkage rate within the same time by the following method.

◎ Heat shrinkage rate: Cut to 10 cmm x 10 cmm square, immerse for 10 seconds under no load in 85 degree hot water, heat shrink, and then immerse for 10 seconds in 25 seconds of water, and measure the length and length of the sample. By the following equation.

Heat shrink rate (%) = 100 x (length before shrink) / (length before shrink)

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

Example 1

PET resin chips with an intrinsic viscosity of 0.80 dl / g and transparent polyester resin chips with an intrinsic viscosity of 0.75 dl / g and a content of 1,4-cyclohexanedimethanol monomer in the polymer of 60 mol% compared to terephthalic acid are used as raw materials It was. The PET resin and the transparent polyester resin were mixed in a 1: 9 ratio in a rotary stirrer, dried at 160 ° C. for 5 hours in a dehumidifying dryer, and then introduced into an injection machine hopper. The temperature of an extruder extrudes a film at the temperature of 260 degreeC, and installs the electrode between an extruder and a casting roll, and sticks a film to a roll, and obtains an unstretched film. The stretched heat shrink film of 100 microns is obtained by stretching the film through tentering.

Example 2

A PET resin and a transparent polyester resin used in Example 1 were prepared in the same manner as in Example 1 except for blending in a 7: 3 ratio.

Example 3

A PET resin and a transparent polyester resin used in Example 1 were prepared in the same manner as in Example 1 except for blending in a 9: 1 ratio.

Comparative Example 1

Except for blending the transparent polyester resin used in Example 1 with a PET resin in a 6: 4 ratio by using a 1, 4- cyclohexane dimethanol monomer 30 mol% compared to terephthalic acid in Example 1 Produced in the same way as.

Comparative Example 2

Except that blended in Example 1 using only the PET resin was produced in the same manner as in Example 1 above.

Comparative Example 3

The same method as in Example 1, except that the 1,4-cyclohexanedimethanol monomer 100% by mole of the terephthalic acid in the copolymerized polyester resin and PET resin blended 3: 7 Was produced.

Comparative Example 4

Except that the intrinsic viscosity of the PET resin in Example 1 was 1.3 dl / g was prepared in the same manner as in Example 1

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 CHDM content 55 mol% 18 mol% 6 mol% 18 mol% 0 mol% 30 mol% 18 mol% Drying time 5 hours 5 hours 5 hours 5 hours of PET resin drying + 6 hours of transparent copolyester polyester resin = 11 hours PET resin drying 5 hours 5 hours 5 hours of PET resin drying + 6 hours of transparent copolyester polyester resin = 11 hours Cooling line installation of Hopper inlet not needed not needed not needed Required (need to be kept below 60 ℃) not needed Required (need to be kept below 60 ℃) not needed Molding temperature (℃) 260 260 260 250 260 270 280 Molding temperature (Die) (℃) 260 260 260 270 260 270 280 Heat Shrinkage (@ 85 ℃) 87% 70% 60% 65% 50% 67% 60 transparency(%) 88.1 86.2 83.5 86.0 78.5 87.6 79.0

As described above, according to the present invention, in the process of adjusting the content of 1,4-cyclohexanedimethanol monomer in order to have a desired maximum heat shrinkage rate, the transparent copolymer with PET resin without undergoing two steps of drying Blending of the polyester resin is possible, and as a result, the problem is easily compensated for by the problems of the PET resin, and thus has an advantage in time and economy. In addition, the resin composition according to the present invention may have a much wider processing temperature range because there is no risk of fusion of chips in the front wheel portion, and the content of 1,4-cyclohexanedimethanol monomer is greater than 30% This makes it possible to apply to products for applications in which higher shrinkage is required.

Claims (8)

1 to 99 mol% of a polyethylene terephthalate (PET) resin having an intrinsic viscosity of 0.50 to 1.2 dl / g; And A diol component having a content of 50 to 80 mol% of 1,4-cyclohexanedimethanol in the transparent co-polyester resin and including one or more diols except for the 1,4-cyclohexanedimethanol; 1 to 99 mol% of a transparent copolyester resin prepared by condensing an acid component; The blend of the polyethylene terephthalate resin and the transparent co-polyester resin, characterized in that 5 to 60 mol% of the 1,4-cyclohexane dimethanol is contained on the basis of the dicarboxylic acid component in the total blended polyester resin Heat shrink film composition. The diol other than the 1,4-cyclohexanedimethanol used in the transparent copolyester polyester resin is 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-cyclohexane A heat shrinkable film composition using a blend of a polyethylene terephthalate resin and a transparent copolyester resin, which is dimethanol or a mixture thereof. The heat shrink film composition using blending of a polyethylene terephthalate resin and a transparent co-polyester resin according to claim 1, wherein the intrinsic viscosity of the PET resin is 0.75 to 0.87 dl / g. [Claim 2] The polyethylene terephthalate resin and the transparent copolymerization of claim 1, wherein the titanium-based polycondensation catalyst is added in the amount of 1 to 100 ppm based on the amount of the titanium element relative to the weight of the final polymer. Heat shrink film composition using blending of polyester resin. The method of claim 4, wherein the titanium catalyst is 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 and titanium dioxide A heat shrinkable film composition using a blend of a polyethylene terephthalate resin and a transparent copolyester resin, which is a zirconium dioxide co-precipitate. 2. The polyethylene terephthalate resin and the transparent copolyester according to claim 1, wherein the stabilizer is added in the amount of 10 to 100 ppm based on the small amount of the weight of the final polymer. Heat shrink film composition using blending of resins. 7. The heat shrinkable film composition according to claim 6, wherein the stabilizer is phosphoric acid, trimethyl phosphate, triethyl phosphate, or triethyl phosphonoacetate. Polyethylene terephthalate resin having intrinsic viscosity of 0.50 to 1.2 dl / g of 1 to 99 mol% of transparent copolyester resin copolymerized with 50 to 80 mol% of 1,4-cyclohexanedimethanol based on the dicarboxylic acid component Mixing 1 to 99 mole% to include 5 to 60 mole% of the 1,4-cyclohexanedimethanol based on the dicarboxylic acid component in the blended total polyester resin; And drying the mixture at a temperature of 120 to 160 ° C., wherein the heat shrinkable film composition is prepared using a blend of a polyethylene terephthalate resin and a transparent co-polyester resin.