KR20120052088A - Environment-friendly heat shrinkable film - Google Patents

Abstract

The present invention relates to an environmentally friendly heat shrink film, comprising a resin in which a first resin containing an aliphatic polycarbonate resin and a second resin containing a biodegradable aliphatic polyester resin are blended and placed in a 90 ° C constant temperature water bath for 10 seconds. When the shrinkage in the main shrinkage direction is more than 30%, and stretched in at least one direction, the eco-friendly heat shrinkable film of the present invention has excellent heat resistance, heat shrinkage and biodegradability, moderate shrinkage stress, friction coefficient and Since the haze is low, it can be used for labeling of food and beverage containers or food packaging overlaps, and by using aliphatic polycarbonate resins, carbon dioxide is reduced and environmentally hazardous substances are hardly emitted even upon incineration or the like.

Description

Eco-friendly heat shrink film {ENVIRONMENT-FRIENDLY HEAT SHRINKABLE FILM}

The present invention relates to an environment-friendly heat shrink film used for labeling or food packaging overlap of food and beverage containers.

As general-purpose heat-shrinkable films, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyester (PET) and the like derived from petroleum are widely used. However, they are produced from petroleum, have high energy consumption, generate large amounts of carbon dioxide, and emit environmentally harmful substances during disposal after use.

For example, polyvinyl chloride (PVC) film not only contains chlorine in the molecule, but also contains additives such as various plasticizers, and thus generates harmful substances such as dioxins during incineration. In addition, polypropylene (PP), polystyrene (PS), polyester (PET), etc., are used for packaging purposes, and when they are landfilled, they accumulate with little degradation due to chemical and biological stability. It causes the problem of soil pollution.

In order to make up for the shortcomings of plastic films that do not decompose, various studies have recently been made on methods of producing films using environmentally friendly aliphatic polycarbonates utilizing high biodegradable polylactic acid (PLA) or carbon dioxide of the resin itself. It is becoming.

However, PLA is limited in label use because the crystallinity is high, the shrinkage rate is fast, and the shrinkage stress is too low, so that the shrinkage finish is not good. In addition, since the aliphatic polycarbonate is an amorphous resin having a low Tg (glass transition temperature), there is a problem in that heat resistance and mechanical properties are insufficient for use as a film alone.

In addition, PET has excellent mechanical properties due to its stable molecular structure, but due to its high shrinkage stress, PET is limited to use for labeling a flexible bottle made of PE, PP, and the like.

Accordingly, there is a demand for the development of a new heat-shrinkable film in which the disadvantages of the existing heat-shrinkable film are compensated for.

Accordingly, an object of the present invention is to provide a film useful for a label or a packaging material because it is environmentally friendly and has excellent heat shrinkage and heat resistance.

In order to achieve the above object, the present invention consists of a resin blended with a first resin containing an aliphatic polycarbonate resin, and a second resin containing a biodegradable aliphatic polyester resin, and placed in a 90 ° C constant temperature water bath for 10 seconds. When the shrinkage in the main contraction direction is 30% or more, and at least one direction is provided, provides an eco-friendly heat shrink film.

In addition, the present invention provides a heat shrink label or packaging material comprising the eco-friendly heat shrink film.

Eco-friendly heat shrink film according to the present invention is excellent in heat resistance, heat shrinkage and biodegradation, moderate shrinkage stress, low coefficient of friction and haze, can be used for food and beverage containers labels or food packaging overlap, etc., aliphatic By using polycarbonate resins, carbon dioxide is reduced and environmentally hazardous substances are hardly emitted even when disposed of incineration.

The film according to the present invention is composed of a resin in which a first resin containing an aliphatic polycarbonate resin and a second resin containing a biodegradable aliphatic polyester resin are blended and placed in a 90 ° C. constant temperature water bath for 10 seconds. Shrinkage in the shrinkage direction is 30% or more, characterized in that it is stretched in at least one direction.

The aliphatic polycarbonate resin used in the substrate layer may be prepared by copolymerizing carbon dioxide with an epoxide compound selected from the group consisting of alkylene oxide, cycloalkene oxide, and mixtures thereof. In this case, as the polymerization catalyst, a zinc precursor such as diethyl zinc (US Pat. No. 3,585,168), a complex compound containing an onium salt (Korean Patent No. 10-0853358), or a cobalt catalyst may be used.

Specific examples of the epoxide compound include ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, decene oxide, dodecene oxide, tetradecene oxide, hexadecene oxide, octadecene oxide, butadiene monooxide, 1 , 2-epoxide-7-octene, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, cyclododecene oxide, 2,3-epoxide norbornene, limonene oxide and mixtures thereof.

When copolymerizing aliphatic polycarbonate resin, the pressure of carbon dioxide may be from normal pressure to 100 atmospheres, preferably 5 to 30 atmospheres. In addition, the polymerization temperature may be 20 ℃ to 120 ℃, preferably 50 ℃ to 90 ℃.

As a method of copolymerizing an aliphatic polycarbonate resin, there exist a batch polymerization method, a semi-batch polymerization method, a continuous polymerization method, etc. When using a batch or semi-batch polymerization method, the reaction time may be 1 hour to 24 hours, preferably 1.5 hours to 4 hours, and when using the continuous polymerization method, the average residence time of the catalyst is likewise 1.5 hours to 4 hours. It is preferable to set it as time.

Specific examples of the aliphatic polycarbonate resin include preferably polyethylene carbonate, polypropylene carbonate and mixtures thereof.

The number average molecular weight (Mn) of the aliphatic polycarbonate resin used in the present invention may be 50,000 to 500,000. Here, the number average molecular weight (Mn) means the number average molecular weight measured by GPC by correcting the polystyrene of a single molecular weight distribution with a standard.

In general, aromatic polycarbonates are very dangerous from the manufacturing process because they are manufactured using the toxic substances bisphenol-A and phosgene, while aliphatic polycarbonates utilize carbon dioxide to reduce carbon dioxide emitted to the atmosphere. It also has the advantage of contributing to. In addition, aromatic polycarbonates do not cause natural decomposition and emit environmentally harmful substances when incinerated, but aliphatic polycarbonates can be decomposed into carbon dioxide and water upon incineration.

In the present invention, such a non-crystalline aliphatic polycarbonate can be used as the substrate layer to ensure a sufficient shrinkage rate for labeling.

The film of the present invention comprises a resin blended with a second resin containing a biodegradable aliphatic polyester resin in order to improve heat resistance and post-processability.

As the biodegradable aliphatic polyester resin, polylactic acid, polylactic acid copolymer, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, polybutylene adipic terephthalate, and mixtures thereof It may be selected from the group consisting of, it is preferable that the melting temperature is more than 60 ℃ crystalline resin.

The number average molecular weight (Mn) of the biodegradable aliphatic polyester resin used in the present invention may be 1,000 to 500,000.

The second resin protects the amorphous aliphatic polycarbonate with crystalline biodegradable aliphatic polyester, thereby improving heat resistance and excellent post-processability, and at the same time solves the problem of shrinkage caused by too low shrinkage stress of the biodegradable material. Biodegradability can be improved.

The first resin and the second resin can be added to the conventional electrostatic agent, antistatic agent, antioxidant, heat stabilizer, sunscreen, antiblocking agent, other inorganic lubricants within the range that does not impair the effects of the present invention, Preferably, it may be added in the range of 0.01% to 10.0% by weight relative to the total weight of the film.

The blending ratio of the first resin and the second resin is preferably 1: 0.25 to 1:99 by weight.

Moreover, it is preferable that the heat shrink film of this invention is 5 micrometers-500 micrometers in thickness.

In the heat shrinkable film according to the present invention, the first resin containing the aliphatic polycarbonate resin and the second resin containing the biodegradable aliphatic polyester resin are blended, and additives are mixed as necessary, followed by mixing the mixed resin. It can be prepared by melt extrusion, stretching and heat setting.

At this time, it is possible to produce a bidirectional shrinkage film by biaxially stretching the unstretched sheet in the longitudinal direction and the transverse direction, or to uniaxially stretch in only one of the longitudinal direction and the transverse direction to produce the unidirectional shrinkage film.

In addition, the melt extrusion temperature is preferably 150 ℃ to 280 ℃, the temperature of the stretching step is preferably 50 ℃ to 100 ℃, for each direction The draw ratio is preferably 1.5 times to 10.0 times and more preferably 2.5 times to 5.0 times. In addition, the heat setting temperature is preferably 50 ℃ to 150 ℃. When the process conditions are within the above range, it is possible to more easily implement the heat shrink rate pursued in the present invention.

In the case of the bidirectional shrinkage film, in order to balance the shrinkage in both directions, the relaxation after heat setting may be reduced to 0.01% to 5%. It is also possible to give back relaxation from -0.01% to -5.0% to impart adequate shrinkage stress.

Such a heat shrink film according to the present invention is excellent in heat shrinkage, shrinkage stress, coefficient of friction, heat resistance, haze and biodegradation.

When the film of this invention is left for 10 second in 90 degreeC constant temperature water bath, the shrinkage rate of the main contraction direction shows 30% or more. When the heat shrinkage is in the above range, it is easy to apply the film to various types of containers and uses.

In addition, preferably, the maximum shrinkage stress is 1.0N to 9.0N when left for 10 seconds in a 90 ° C constant temperature water bath. When the maximum shrinkage stress is in the above range, the finish can be better after the heat shrink of the film, it can also be applied to a flexible bottle of PE or PP material.

Also preferably, the coefficient of kinetic friction is less than 0.70 and the coefficient of static friction is less than 0.65. When the coefficient of friction is within the above range, it is possible to more effectively prevent the films from sticking together during the stretching process or hot filling.

In addition, the haze preferably has a transparency of 30% or less can be used for a variety of packaging applications, has a biodegradability of 20% or more as environmentally friendly.

Such a heat shrink film of the present invention is suitable as a heat shrink label or packaging material use. Such heat shrinkable labels or packaging materials are preferably usable for labeling of food and beverage containers or for overlapping of food packaging. For example, when used as a heat-shrinkable label can be produced by stretching in one direction, when used as a packaging material such as overlap can be produced by stretching in both directions.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

The film according to the present invention and the prior art was prepared as follows, and the configuration and process of each film are summarized in Table 1 below.

Example 1: Preparation of PPC / PLA Blended Resin Film

As the first resin, polypropylene carbonate resin (QPAC40, Empower Co., Ltd.), an aliphatic polycarbonate obtained by alternating copolymerization of carbon dioxide and propylene oxide, was used, and polylactic acid resin (melting point: 145 ° C, 4042D, NatureWorks) was used as the second resin. Used.

The first and second resins were blended at a weight ratio of 70:30, and tris (2,4-di- t -butylphenyl) phosphite (RICHFOS 168, Yeongju) as a heat stabilizer relative to 100 parts by weight of the blending resin. 1.0 weight part and 3.0 weight part of polylactic acid (SKC) which substituted the terminal group with maleic anhydride as a compatibilizer were added.

The resin was melt extruded at 190 ° C. and cooled on a casting roll at 10 ° C. to obtain an unstretched film. The unoriented film was laterally stretched five times at 65 ° C., and then heat-set at 60 ° C. to produce a film having a thickness of 50 μm.

Example 2: Preparation of PPC / PBS Blended Resin Film

As the first resin, polypropylene carbonate resin (QPAC40, Empower Co., Ltd.), an aliphatic polycarbonate obtained by alternating copolymerization of carbon dioxide and propylene oxide, was used, and polybutylene succinate resin (melting point: 105 DEG C, G4560, since the second resin) was used. Chemistry).

The first and second resins are blended at a weight ratio of 70:30, and tris (2,4-di- t -butylphenyl) phosphite (RICHFOS 168, Yeongju) as an antioxidant relative to 100 parts by weight of the blending resin. To 3.0 parts by weight was added.

The mixed resin was melt extruded at 190 ° C. and cooled in a casting roll at 15 ° C. to obtain an unstretched film. The unoriented film was longitudinally stretched three times at 65 ° C. and transversely stretched four times at 80 ° C., and then heat-set at 60 ° C. to produce a film having a thickness of 20 μm.

Comparative Example 1: Preparation of PPC Single Resin Film

As the raw material resin, polypropylene carbonate resin (QPAC40, Empower Co., Ltd.), an aliphatic polycarbonate obtained by alternating copolymerization of carbon dioxide and propylene oxide, was used.

The raw material resin was melt extruded at 170 ° C. and cooled in a casting roll at 10 ° C. to obtain an unstretched film. The unoriented film was longitudinally stretched 1.5 times at 70 ° C. and transversely stretched 4 times at 100 ° C., and then heat-set at 50 ° C. to produce a film having a thickness of 20 μm.

Comparative Example 2: Preparation of PPC / PET Blended Resin Film

Polypropylene carbonate resin (QPAC40, Empower), an aliphatic polycarbonate obtained by alternating copolymerization of carbon dioxide and propylene oxide, was used as the first resin, and polyethylene terephthalate resin (melting point: 250 ° C, SKC) was used as the second resin. The first and second resins were blended in a weight ratio of 50:50.

The blended resin was melt extruded at 240 ° C. and cooled on a casting roll at 20 ° C. to obtain an unstretched film. The unoriented film was laterally stretched three times at 85 ° C., and then heat-set at 120 ° C. to produce a film having a thickness of 50 μm.

Comparative Example 3: Preparation of PLA Single Resin Film

Polylactic acid resin (melting point: 170 degreeC, 4032D, NatureWorks) was used as raw material resin.

The raw material resin was melt extruded at 230 ° C. and cooled in a casting roll at 20 ° C. to obtain an unstretched film. The unoriented film was laterally stretched three times at 105 ° C. and then heat-set at 165 ° C. to produce a film having a thickness of 50 μm.

After performing the physical property measurement and performance evaluation for the films prepared according to the Examples and Comparative Examples in the following manner, the results are shown in Table 1 below.

(1) heat shrinkage

The film sample was cut into a length of 200 mm and a width of 15 mm in the direction to measure the shrinkage rate, treated in a constant temperature water bath maintained at a temperature of 90 ° C. for 10 seconds, and then the change in length was measured. Calculated.

Equation 1

Thermal contraction rate (%) = (length before heat treatment-length after heat treatment) / length before heat treatment x 100

(2) shrinkage stress

The maximum stress was measured when soaked in a 90 ° C. constant temperature water bath for 10 seconds using a stress gauge (QM150S, Cumsys) equipped with a load cell.

(3) heat resistance

After labeling the film in the bottle, when the 70 ℃ liquid is filled in the bottle, it was confirmed whether or not blocking occurs between the bottles and evaluated by the following criteria.

Excellent: Bottles are not fused at all.

Good: Bottles stick together but can be removed after cooling.

Poor: Bottles do not fuse together.

(4) haze

The haze of the film was measured according to ASTM D1003 using a haze meter (SEP-H, Nihon Semitsu Kogaku).

(5) biodegradability

The biodegradability of the film was measured according to ASTM D5338.

division unit Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Configuration Kinds First resin PPC PPC PPC PPC PLA 2nd resin PLA PBS - PET - 1/2 resin content ratio 70/30 70/30 100 50/50 - additive Heat stabilizer
Compatibilizer Antioxidant - - - fair Stretch spurn Biaxial Biaxial spurn spurn Elongation ratio Longitudinal direction ship - 3 1.5 - - Transverse ship 5 4 4 3 3 Heat setting temperature ℃ 60 60 50 120 165 Properties Heat shrinkage Longitudinal direction % 3 35 15 One 5 Transverse % 45 50 40 10 0.5 Maximum Shrinkage Stress 2.8 2 2.5 0.8 0.7 Heat resistance Good Good Bad Good Good Hayes % 5 20 5 70 One Biodegradability % 30 30 0 0 110

As can be seen in Table 1, the film of Examples 1 to 2 according to the present invention is generally excellent in the heat shrinkage in one direction or in both directions compared to the film of Comparative Examples 1 to 3, the shrinkage stress is also suitable as a heat shrink film. In addition, because of excellent heat resistance and biodegradability, and low haze, it is suitable for labels or overlapping packaging materials for containers such as food and beverage.

Claims (10)

It consists of a resin blended with a first resin containing an aliphatic polycarbonate resin and a second resin containing a biodegradable aliphatic polyester resin, and the shrinkage in the main shrinkage direction is 30% when placed in a 90 ° C. constant temperature water bath for 10 seconds. Environmentally-friendly heat-shrink film extended | stretched in at least one direction as mentioned above.
The method of claim 1,
Eco-friendly heat shrink film, characterized in that the aliphatic polycarbonate resin is obtained by copolymerization of carbon dioxide and epoxide compound selected from the group consisting of alkylene oxide, cycloalkene oxide and mixtures thereof.
The method of claim 1,
Eco-friendly heat shrink film, characterized in that the aliphatic polycarbonate resin is selected from the group consisting of polyethylene carbonate, polypropylene carbonate and mixtures thereof.
The method of claim 1,
Eco-friendly heat shrink film, characterized in that the aliphatic polycarbonate resin has a number average molecular weight (Mn) of 50,000 to 500,000.
The method of claim 1,
The biodegradable aliphatic polyester resin is polylactic acid, polylactic acid copolymer, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, polybutylene succinate, polybutylene dipic terephthalate, and mixtures thereof An environmentally friendly heat shrink film, characterized in that selected from the group consisting of.
The method of claim 1,
The eco-friendly heat shrink film, at least one additive selected from the group consisting of an electrostatic agent, an antistatic agent, an antioxidant, a heat stabilizer, a sunscreen, an antiblocking agent, and an inorganic lubricant, 0.01% by weight to 10% by weight relative to the total weight of the film Eco-friendly heat shrink film, characterized in that added in the range of%.
The method of claim 1,
The blending ratio of the first resin and the second resin is 1: 0.25 to 1:99, characterized in that the weight ratio of, eco-friendly heat shrink film.
The method of claim 1,
The eco-friendly heat-shrink film is stretched at a draw ratio of 1.5 times to 10.0 times at a stretching temperature of 50 ℃ to 100 ℃ with respect to at least one of the longitudinal direction and the transverse direction, characterized in that it is heat-set at 50 ℃ to 150 ℃ , Eco-friendly heat shrink film.
The method of claim 1,
The eco-friendly heat shrink film, the maximum shrinkage stress is 1.0N to 9.0N when placed in a 90 ℃ constant temperature water bath, haze is 30% or less, characterized in that the biodegradability is 20% or more, eco-friendly heat shrink film.
A heat shrink label or packaging material comprising the environmentally friendly heat shrink film of claim 1.