KR20050117240A - Polyester shrinkable film - Google Patents

Abstract

The present invention is a polyester shrink film prepared from a copolymer composition of propylene terpolymer alone or mixed with polyethylene terephthalate containing dimethyl terephthalate as a dicarboxylic acid component, diethylene glycol 10 to 90 mol% as a diol component Since diethylene glycol added as a silver copolymerization component can lower the melting point of the polyester resin, it is economical and excellent in shrinkage characteristics because the shrinkage characteristic can be imparted to the polyester film by using a thermodynamic primary transition near the lower melting point. .

Description

Polyester shrinkable film {Polyester shrinkable film}

The present invention relates to a polyester shrink film, and more particularly, in a shrink film obtained from a polyester resin prepared from diol and dicarboxylic acid, prepared from a composition containing 10 to 90 mol% of diethylene glycol as the diol component. The film produced from the copolymerized polyester alone or mixed with polyethylene terephthalate can impart shrinkage properties by using a melting point which is a thermodynamic primary transition, and thus relates to a polyester shrink film having excellent shrinkage properties.

Polyethylene terephthalate (PET) molded articles, which are currently produced industrially, are widely used in fibers, films and other molded articles. In particular, polyethylene terephthalate films obtained from aromatic dicarboxylic acids and glycols have excellent heat resistance, tensile strength, elongation, Young's modulus, elastic recovery, impact resistance, and the like. Due to its mechanical properties, dimensional stability, and electrical insulation, it is widely used for industrial materials and agricultural materials such as magnetic recording tapes, photographic films, insulating materials, and films to be deposited.

In addition, it is excellent in chemical properties such as chemical resistance, weather resistance, water resistance, transparency, supplementary property, water resistance, gas barrier property, etc. The usage is also increasing significantly.

In particular, due to changes in the distribution process, shrink films have been used for various applications, such as packaging to bundle several products in a large discount store or for attaching printed materials (for labels) of various containers. In addition, since the use of PVC is regulated due to environmental hormones in the label market, which has recently been used as PVC, the use of PVC is increasing in terms of recycling.

In general, the industrial production method of polyethylene terephthalate film melt-extruded polyethylene terephthalate polymer and cooled in a cooling drum to prepare an amorphous sheet, stretched, heat-set to obtain a biaxially stretched film. At this time, polyethylene terephthalate used in the production of polyethylene terephthalate film is usually produced by direct esterification reaction with dicarboxylic acid such as terephthalic acid and ethylene glycol as main components and heating to a reaction temperature of 200 to 280 ° C under normal pressure or pressure.

In addition, the bis (beta-hydroxyethyl) tere is a main component obtained by a transesterification reaction in which a dimethyl carboxylate such as dimethyl terephthalate and a glycol such as ethylene glycol are used as a main component and heated to a reaction temperature of 140 to 240 ° C in the presence of a catalyst. There is a method of obtaining phthalates and their low molecular weight condensates (esterified products) and subsequently heating them to a reaction temperature of 260 to 300 DEG C with a polycondensation catalyst under high vacuum to polycondensate them.

In general, PET resin is a polymer having excellent thermal stability and dimensional stability, but when such a resin is used as a shrink film, such thermal stability acts as a deterrent.

In general, the shrink film is usually used by the hot air treatment at a temperature of 70 ~ 80 ℃ or more.

However, when the PET resin is used alone at such a heat treatment temperature, the shrinkage is limited to 30% level, and in order to obtain a high shrinkage rate, the shrinkage temperature must also be raised to 100 ° C. or more. When the heat treatment temperature is increased, it is preferable to maintain the heat treatment temperature at 100 ° C. or lower because it may cause deterioration of the packaged material.

Conventionally, high shrink films for imparting shrinkage characteristics include NPG (2,2-dimethyl-1,3-propanediol) and CHDM (1,4- as diol-based components from companies such as Toyobo, Eastman Kodak, and SKC. Cyclic hexane dimethanol); In addition, IPA (isophthalic acid) or adipic acid was used as a dicarboxylic acid component as a copolymerization component, thereby imparting a fluid structure capable of flexibly shrinking after stretching by interfering with the crystallinity of PET. This fluidity is that the polymer chain is moving, the polymer chains fixed in the heat treatment and cooling process after stretching may have fluidity near the Tg of the PET. Therefore, by using the transition behavior near Tg, not only the shrinkage characteristics but also the heat setting temperature at a temperature below Tg gives the shrinkage effect due to residual stress.

However, the technology used in such a company is economically burdened because it uses expensive copolymer monomer, and since it uses Tg, which is a secondary transition, technically, since it can be given a shrinkage characteristic only when it is raised to a temperature above Tg of the resin. There have been many difficulties in work.

Therefore, in order to lower the heat treatment temperature for imparting shrinkage properties to 100 ° C. or less, it is necessary to design a structure of a polymer having shrinkage properties at low temperature by using a copolymerization component in PET.

Therefore, the present inventors, while trying to find a method that can effectively give the shrinkage characteristics by solving the problems caused when the heat treatment near the conventional secondary transition Tg to give the shrinkage characteristics to the PET film, PET manufacturing The diethylene glycol added as a result of preparing the film alone or in a mixed composition with polyethylene terephthalate was prepared from a composition containing diethylene glycol as a diol component in a specific content. By lowering the melting point of, a polyester copolymer having a low Tm near the conventional PET Tg was obtained, and a shrinkage characteristic was imparted near the melting point of Tm, thereby producing a polyester film exhibiting excellent shrinkage behavior. It has been found that the present invention has been completed.

Accordingly, an object of the present invention is to provide a polyester film capable of imparting shrinkage characteristics by using a melting point that is a primary transition.

The polyester shrink film according to the object of the present invention comprises a dimethyl terephthalate as a dicarboxylic acid component, and copolymerized polyester resin alone or polyethylene terephthalate containing 10 to 90 mol% of diethylene glycol as the diol component It is characterized in that it is prepared from the mixed composition of.

The present invention is excellent in shrinkage characteristics produced from the mixing composition of the copolymerized polyester or polyethylene terephthalate containing 10 to 90 mol% of diethylene glycol as the diol component when preparing a polyester shrink film from dicarboxylic acid and diol It relates to a polyester film.

Dicarboxylic acids used in the preparation of the polyester shrink film of the present invention are aromatic dicarboxylic acids such as dimethyl terephthalate, terephthalic acid, isophthalic acid and adipic acid.

In addition, the diol necessarily contains 10 to 90 mol% of diethylene glycol, and may be mixed with other alkylene glycols such as ethylene glycol, neopentyl glycol, and butylene glycol.

When the content of the diethylene glycol is less than 10 mol%, the melting point decrease of the copolymer in the diethylene glycol is less effective in using the thermodynamic primary transition point in the present invention, and in the case of exceeding 90 mol% polyester Due to high physical property degradation, problems arise in practical use.

In the present invention, it is also possible to use the copolyester resin prepared as described above alone or mixed with polyethylene terephthalate. Although the mixing ratio of co-polyester resin and PET resin is not specifically limited, Preferably it is 30: 70-70: 30. In addition, polyethylene terephthalate which can be mixed and used at this time is the conventional polyethylene terephthalate resin manufactured from terephthalic acid and ethylene glycol.

In the case of mixing with the PET resin, it is used by mixing by compounding or the like, and at this time, it is also possible to add a lubricant (low molecular weight additive), blocking inhibitor (inorganic filler) and the like as an additive.

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

Example

Examples 1-4 and Comparative Examples 1-4

Next, as shown in Table 1, dimethyl terephthalate as a dicarboxylic acid component and diethylene glycol, ethylene glycol and neopentyl glycol were added as a diol component to prepare a polyethylene terephthalate resin.

The copolymer PET resin thus prepared was melt extruded alone or mixed with PET resin and cooled in a cooling drum to prepare an amorphous sheet. Then, the film obtained by 4-fold uniaxial stretching in the TD direction at the extending | stretching temperature of 90 degreeC was obtained. Then, heat treatment was carried out at 70 ° C. for 30 seconds to obtain a shrink film having a final thickness of 40 μm.

In particular, in Examples 1, 3 to 4, a mixture of PET resin and compounding was used before extrusion.

The heat shrinkage and the maximum shrinkage temperature in the TD direction of the prepared polyester shrink film were measured as follows, and the results are shown in Table 2 below.

1. The heat shrinkage rate (%) in the TD direction was set to an initial length of 20 cm, and treated in 80 ° C. hot water for 10 seconds, and measured by the following equation.

Thermal contraction rate (%) = strain length (initial length-length after strain) / initial length X 100

2. The maximum shrinkage temperature was measured by using a TM-7000 manufactured by Ulvac-Rico Co., Ltd., at a temperature of 10 ° C./min for a 4 × 4 mm size sample at a temperature increase rate of 10 ° C./min.

PET (wt%) Diol content in copolymerized PET DEG (mol%) EG (mol%) Neopentyl glycol (mol%) Mixed amount with PET (wt%) Example 1 70 90 10 - 30 Example 2 - 50 50 - 100 Example 3 80 90 10 - 20 Example 4 50 20 60 20 50 Comparative Example 1 100 - - - - Comparative Example 2 - 100 - - 100 Comparative Example 3 - 5 95 - 100 Comparative Example 4 TPA / EG / CHDM = 100/83/17

Heat shrinkage in the TD direction (80 ° C) Maximum Shrinkage Temperature (℃) Example 1 52 84.6 Example 2 45 83.3 Example 3 43 86.6 Example 4 62 80.3 Comparative Example 1 28 110.2 Comparative Example 2 - - Comparative Example 3 23 105.5 Comparative Example 4 63 92.6

From the results of Table 2, the shrink film produced according to the present invention can be confirmed that the excellent heat shrinkage at 80 ℃, the maximum shrinkage temperature is 100 ℃ or less.

However, in the case of Comparative Example 1, the film is made from a general PET resin, and due to the high stress and the low shrinkage rate, the shrinkage characteristics required in the shrink film are not met. In the case of Comparative Example 2, the melting point is so low that the sheet is too good to flow. There is a difficulty in molding. In addition, in the case of Comparative Example 3, the content of DEG is too low to have a low effect of the copolymer, thereby simultaneously exhibiting problems of shrinkage stress and shrinkage rate. Particularly, in the case of Comparative Example 4, the physical properties show similar characteristics to the present invention, but this is different from the present invention to impart shrinkage characteristics using the glass transition temperature as the secondary transition.

As described above in detail, according to the present invention, the polyester shrink film prepared by including a certain amount of diethylene glycol as a diol component in the manufacture of the polyester shrink film can impart shrinkage characteristics using the melting point of the first transition, Economical and excellent shrinkage characteristics.

Claims (5)

A polyester shrink film prepared from a copolymerized polyester resin alone or a mixed composition with polyethylene terephthalate containing dimethyl terephthalate as the dicarboxylic acid component and diethylene glycol 10 to 90 mol% as the diol component. 2. The polyester shrink film according to claim 1, wherein the shrink film has a shrinkage of 30 to 80%. The polyester shrink film of claim 1, wherein the dicarboxylic acid component further comprises at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid and adipic acid. The polyester shrink film of claim 1, wherein the diol component further comprises at least one selected from ethylene glycol, neopentyl glycol, and butylene glycol. The polyester shrink film according to claim 1, wherein the mixed composition of the copolymerized polyester resin and the polyethylene terephthalate is 30: 70-70: 30.