KR100933242B1 - Biodegradable MDO Heat Shrink Film for Labels and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to an MDO heat shrink film that has printability, sealability, transparency and excellent mechanical properties for shrink labels of containers and decomposes in a natural environment.

The present invention provides a biodegradable MDO heat shrink film obtained by mixing a biolactic acid-based polylactic acid polymer, polybutylene succinate adipate and an aliphatic polyester in a weight ratio of 90: 1: 9 to 90: 9: 1. It features.

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Description

Biodegradable MDO Heat-shinkable Film for Label and Production Method therof}

1 schematically shows a drawing device used to draw a film;

<Explanation of symbols for the main parts of the drawings>

R1, R2: preheat roller,

R3: low speed roller,

R4: high speed roller,

R5: annealing roller,

R6: Cooling Roller

The present invention relates to a biodegradable MDO heat shrink film and a method for manufacturing the same, which is naturally decomposed in a natural environment, has excellent processability in the extrusion and stretching process, and has excellent transparency, printability, adhesion to solvents, and shrinkage characteristics. An MDO heat-shrink film and a method of manufacturing the same.

MDO heat shrink film is widely used for labeling of glass bottles, plastics, batteries, cooking oil, food, detergents, etc.In order to be used for labels, physical properties such as solvent resistance, heat resistance and weather resistance are required. Excellent shrinkage uniformity in the machine direction).

There have been various problems in the case of heat shrink films of polystyrene, polyethylene terephthalate, and polyvinyl chloride, which are used as conventional TDO heat shrink films.

Polystyrene film has a problem in printability, so it is difficult to use a general ink for plastics, so it is inconvenient to use a special ink, and in particular, a large shrinkage rate requires great care in transportation and storage.

The polyethylene terephthalate film has excellent heat resistance, chemical resistance, and weather resistance, but various problems have occurred when labeling a container because of high shrinkage stress and high shrinkage speed. If the shrinkage stress is large, the volume of the container of the plastic is reduced, there is a problem that the content of the content is reduced, the rapid shrinkage rate results in a drop in the value of the product due to shrinkage nonuniformity.

In particular, the polyvinyl chloride film contains a chlorine component, which causes a large amount of harmful substances such as hydrogen chloride and dioxins to be emitted during incineration, which is not environmentally friendly.

Due to this problem, the waste plastics of the film are buried in landfills, but the waste plastics are impaired in stabilization of landfills due to the degradability of waste plastics, shorten the use period, and degrade the soil. Plastics are a serious hazard to natural ecosystems.

In order to solve such problems of environmental pollution related to waste plastics, there is increasing interest in the necessity and method of environmental conservation.

Therefore, research and development of environmentally friendly and harmless biodegradable plastics that can be used simply like ordinary plastics and decomposes in a natural environment after use are being actively conducted.

One example is polylactic acid. Polylactic acid is hydrolyzed in soil and converted into harmless decomposition products by microorganisms.

SUMMARY OF THE INVENTION An object of the present invention is to provide a biodegradable MDO heat shrink film that can easily separate a sticker label attached to a plastic container or a glass container.
It is still another object of the present invention to provide a biodegradable MDO heat shrink film at the time of landfill due to the disposal of the container.

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According to the present invention, the above object is a biodegradable MDO heat shrink characterized in that a polybutylene succinate co-adipate (PBSA) and an aliphatic polyester are mixed on a polylactic acid polymer substrate which is a biodegradable raw material. Achieved by a film.

According to the present invention, the preferred weight ratio of the polylactic acid polymer, polybutylene succinate adipate and aliphatic polyester is 90: 1: 9 to 90: 9: 1.

The use of biodegradable MDO heat shrink films as labels in containers such as plastics, bottles, etc. can be used more effectively than TDO shrink label films and is expected to be a new turning point in the market of undeveloped biodegradable MDO shrink labels.

Biodegradable MDO heat shrink film can be suggested as an advanced alternative to resource conservation and pollution problems, and it can be said to be environmentally friendly because the recycling of containers and materials after use is effective.

Currently, the TDO heat shrink label packaging method is widely known as a method of packaging a container by a heat shrink label. TDO heat shrink label packaging method is a method of making a label with heat shrink film, and then attaching the shrink label in the up and down direction of the container in a label packaging machine and then attaching it through a heat shrink tunnel.

Typically, the packaging process of TDO heat shrink film labels consists of four steps: printing, cutting, sealing and labeling.

However, the packaging process of MDO heat shrink film label is simpler than the TDO heat shrink film process because it consists of three steps of printing, cutting and labeling, unlike the conventional TDO heat shrink film packaging process. In addition, since the label is attached or adhered to the container by winding it in a circular method, it is simpler than the packaging method of the conventional TDO heat shrink film, thereby increasing the yield per hour.

In addition, since MDO heat shrink film is made of vegetable raw materials such as corn, potato, tapioca, sweet potato, wheat, and rice, no harmful gas is generated during combustion than the label of TDO heat shrink film mainly made of mineral oil. It is environmentally friendly.

These advantages enable the biodegradable MDO heat shrink film to enter the eco-friendly field that could not be achieved by the TDO heat shrink film made of a conventional mineral oil material.

According to the present invention, a polybutylene succinate adipate (PBSA) prepared by polymerizing at least one alkyl glycol and at least one aliphatic polyfunctional acid is mixed with a polylactic acid polymer which is a biodegradable raw material, A biodegradable MDO heat shrink film with improved processability and tensile strength is prepared.

In the present invention, the biodegradable MDO film material mixed in a certain amount of composition ratio is extruded through a coat hanger type T dice, which is an improvement of the linear T dice. T-die is designed to prevent the retention of biodegradable resin through the hot melt extruder, which does not change the extrusion amount and releases the resin at a uniform speed, and has good kneading dispersion and discharge of bubble mixing.

   The molding machine for extruding the biodegradable film fabric is kneaded to make a mixture of polylactic acid polymer, PBSA and aliphatic polyester into a uniform composition, rather than twin screw extruder (coaxial and reverse rotation) with uniform resin delivery stability and resin residence time. This good single screw extruder is used.

   The biodegradable resin melt-extruded through the T dice is stored in a cooling tank in which water cooled in a cooler is stored, and then quenched by a cooling roll cooled by a circulation pump, and then passed through several guide rolls for uniformity and transparency. This excellent film is produced.

  When low-molecular substances are contained in the biodegradable fabric formed by extruding polylactic acid polymer having a melting point of 150 to 160 ° C., these substances diffuse to the surface of the film to be oozed out, and the film is adhered and integrated by the temperature and pressure at the time of winding. The phenomenon occurs. Because of this, the productivity and processability of the shrink film production is degraded, and the appearance of the film is largely damaged.

Therefore, in the present invention, in order to produce an excellent biodegradable MDO heat shrink film, 300 to 5000 ppm of oleic acid amide having a melting point of 50 to 100 ° C, 350 to 6000 ppm of calcium stearate and 300 to 5000 ppm of stearyl amide are added. In addition, in order to prevent blocking and to adjust the crystallinity and crystallization rate, 50 to 1500 ppm of inorganic particles SiO 2 (silica) and 200 to 1500 ppm of talc are added. The inorganic particles may be added in a master batch method during extrusion, the average particle diameter of the inorganic particles is 1 to 5㎛, preferably 2 to 3㎛.

Amorphous biodegradation that can be quenched and stretched immediately after melt-extruding a semi-crystalline polymer in which a polylactic acid polymer is mixed with PBSA having a melting point of 95 to 125 ° C and an aliphatic polyester having a melting point of 60 to 125 ° C. Made of castle fabric. The biodegradable fabric thus made is passed through an MDO drawing machine. The fabric passing through the MDO stretching apparatus is passed between the roller and the roller made by combining several rollers, as shown in FIG.

  In the stretching method using the MDO stretching apparatus, the biodegradable fabric passes through the first roller (R1, preheat roller) and passes through the second roller (R2, preheat roller). The 1st roller R1 and the 2nd roller R2 are equipped with 70 degreeC-80 degreeC preheating apparatus in order to make extending | stretching of longitudinal direction MD smooth. The sufficiently preheated biodegradable fabric passes through a third roller (R3, low speed roller) and a fourth roller (R4, high speed roller), which are devices for stretching in the longitudinal direction. The temperature of R3 and R4 is set below the melting point of the blend.

The speed of R3, the device for stretching, is adjusted to 20 to 80 m / min, and the speed of R4 is adjusted to operate at 40 to 160 m / min. In this case, the speed ratio of the rollers (R3) and (R4) is 2: 1. The biodegradable fabric passing through the drawing rollers R3 and R4 produces a thin biodegradable MDO film that is longer than the initial fabric area and is reduced in thickness by 1/2, and the draw ratio in the MD direction (length direction) is doubled. The draw ratio which is preferable by this invention is 2-5.

The draw ratio may be determined by adjusting the temperature of R1 and R2 and the temperature and speed of R3 and R4 according to the thickness and shrinkage characteristics of the film. The thickness of the biodegradable MDO film according to the present invention is 5 to 70 µm.

By adjusting the draw ratio and setting the biodegradable fabric to a suitable temperature below the melting point, the orientation of the molecular structure and resin crystallinity of the stretched biodegradable fabric is improved, thereby improving the mechanical strength, optical properties, gas permeability and shrinkage, which are disadvantages of the biodegradable film. To improve.

  Fabrics made of biodegradable polylactic acid-based polymers, PBSA and aliphatic polyester have different processing temperatures depending on melting point, but the temperature of R1 and R2 is controlled to be constant in the preheating process. The temperature of R1 and R2 is 70 degreeC-80 degreeC. If the temperature of R1 and R2 is not constant in the stretching process, it will adversely affect the thickness and shrinkage rate of the stretched biodegradable heat-shrinkable film due to the temperature nonuniformity, and if the speed ratio of R3 and R4 is not constant, the molecular orientation will be in the stretching direction. This non-uniformity causes partial differences in tensile strength and shrinkage in the longitudinal direction of the shrink film. Preferred drawing rollers have a speed ratio of R3 to R4 of 2: 1 to 2:10.

In order to stabilize the fabric having passed through R3 and R4 in the stretching process to stabilize it, the stretching fabric is stabilized by passing through an annealing roller (R5) heated by heat of about 40 to 50 ° C. The speed of the annealing roller R5 is equal to or slightly faster than the speed of R4.

  Since the stabilized fabric is heated while passing through several rollers, the stretched fabric may be deformed, and then passed through a cooling roller R6 of about 30 to 40 ° C. to prevent such deformation. The biodegradable MDO heat-shrink film prepared in this way biodegraded 93.9% after 59 days under 58 ° C 90% RH humidity.

(Example)

Specific examples of the present invention are described below in more detail, but the present invention is not limited thereto.

(Example 1)

150 ppm of inorganic particle silica with an average particle diameter of 1 to 2 µm and talc after mixing 4 weight% of polybutylene succinate adipate and 6 weight% of aliphatic polyester to 90 weight% of polylactic acid polymer having a weight average molecular weight of 200,000 or more 350 ppm was added.

  In addition, in order to improve productivity and processability, 300 ppm of oleic acid amide having a melting point of 50 to 100 ° C., 500 ppm of calcium stearate, and 300 ppm of stearyl amide were added and mixed to prepare a biodegradable fabric using a T-die extruder.

 The prepared biodegradable fabric was stretched 2.5 times in the MD direction (length direction) using an MDO drawing machine device to prepare a biodegradable MDO heat shrink film having a thickness of 25 μm. Shrinkage characteristics of the prepared shrink film is as follows.

50 ℃ 60 ℃ 70 ℃ 80 ℃ 90 ℃ 100 ℃ MD (length) 0% 15% 30% 40% 56% 63% TD (lateral) 0% One% 3% 3% 4% 5%

* Thermal shrinkage test method: Cut the film sample into 120mm in the horizontal and vertical directions, insert the horizontal and vertical 100mm marks in between, immerse them in a hot water bath at each temperature for 30 seconds, and measure the dimensions between the marks. Shrinkage was calculated according to the following equation.

    Heat Shrinkage (%) = (Before Shrinkage-After Shrinkage) / (Before Shrinkage) × 100

(Example 2)

After mixing 3% by weight of polybutylene succinate adipate and 7% by weight of aliphatic polyester to 90% by weight of polylactic acid having a weight average molecular weight of 200,000 or more, 450 ppm of inorganic particle silica having an average particle diameter of 1 to 2 µm and 550 ppm of talc were obtained. Added.

  In addition, in order to manufacture and produce a good biodegradable heat shrink film, 300 ppm of oleic acid amide having a melting point of 50 to 100 ° C., 500 ppm of calcium stearate, and 300 ppm of stearyl amide were added and mixed, and a biodegradable fabric was manufactured using a T-die extruder.

 The prepared biodegradable fabric was stretched three times in the MD direction (length direction) using an MDO drawing machine device to prepare a biodegradable MDO heat shrink film having a thickness of 40 μm. Shrinkage characteristics of the prepared shrink film is as follows.

50 ℃ 60 ℃ 70 ℃ 80 ℃ 90 ℃ 100 ℃ MD (length) 0% 15% 33% 45% 60% 68% TD (lateral) 0% 3% 3% 3% 4% 5%

* Thermal shrinkage test method: cut the film sample into 120mm in the horizontal and vertical directions, insert the horizontal and vertical 100mm marks in between, immerse them in a hot water bath at each temperature for 30 seconds, and measure the dimensions between the marks. Shrinkage was calculated according to the following equation.

    Heat Shrinkage (%) = (Before Shrinkage-After Shrinkage) / (Before Shrinkage) × 100

(Example 3)

After mixing 2% by weight of polybutylene succinate adipate and 8% by weight of aliphatic polyester to 90% by weight of polylactic acid having a weight average molecular weight of 200,000 or more, 300 ppm of inorganic particle silica having an average particle diameter of 1 to 2 µm and 700 ppm of talc are obtained. Add.

  In addition, in order to manufacture and produce a good biodegradable heat-shrink film, 300 ppm of oleic acid amide having a melting point in the range of 50 to 100 ° C., 500 ppm of calcium stearate, and 300 ppm of stearyl amide are added and mixed, and a biodegradable fabric is manufactured using a T-die extruder. It was.

 The prepared biodegradable fabric was stretched 2.5 times in the MD direction (length direction) using an MDO drawing machine device to prepare a biodegradable MDO heat shrink film having a thickness of 30 μm. Shrinkage characteristics of the prepared shrink film is as follows.

50 ℃ 60 ℃ 70 ℃ 80 ℃ 90 ℃ 100 ℃ MD (length) 0% 20% 38% 50% 66% 69% TD (lateral) 0% One% 5% 6% 6% 4%

* Thermal shrinkage test method: cut the film sample into 120mm in the horizontal and vertical directions, insert the horizontal and vertical 100mm marks in between, immerse them in a hot water bath at each temperature for 30 seconds, and measure the dimensions between the marks. Shrinkage was calculated according to the following equation.

    Heat Shrinkage (%) = (Before Shrinkage-After Shrinkage) / (Before Shrinkage) × 100

As seen in the above examples, the shrink film according to the present invention has excellent shrinkage characteristics at a temperature of 80 ° C to 100 ° C.

Since the shrink film according to the present invention has excellent shrinkage characteristics at a temperature of 80 ° C. to 100 ° C., the sticker label attached to the plastic container or the glass container can be easily separated, thus saving time in recycling the plastic container or the glass container. And productivity is improved.

Claims (7)

delete A polylactic acid polymer having a weight average molecular weight of 200,000 or more and a melting point of 150 to 160 ° C. is blended with a polybutylene succinate adipate having a melting point of 95 to 125 ° C. and an aliphatic polyester having a melting point of 60 to 125 ° C. In the label MDO heat shrink film, The weight ratio of the polylactic acid polymer, the polybutylene succinate adipate and the aliphatic polyester is 90: 1: 9 to 90: 9: 1, biodegradable MDO heat shrink film for labels. 3. The compound is added with 300 to 5000 ppm of oleic acid amide having a melting point of 50 to 100 DEG C, 350 to 6000 ppm of calcium stearate and 300 to 5000 ppm of stearyl amide, and 50 to 1500 ppm of silica as an inorganic particle and 200 to 1500 ppm of talc. Biodegradable MDO heat shrink film for labels, characterized in that the addition of. The biodegradable MDO heat shrink film for labels according to claim 3, wherein the inorganic particles have an average particle diameter of 1 to 5 mu m. The biodegradable MDO heat shrink film for labels according to claim 2, wherein the film has a thickness of 5 to 70 μm. Blending a polybutylene succinate adipate having a melting point of 95 to 125 ° C. and an aliphatic polyester having a melting point of 60 to 125 ° C. to a polylactic acid polymer having a weight average molecular weight of 200,000 or more and a melting point of 150 to 160 ° C., Adding 300 to 5000 ppm of oleic acid amide having a melting point of 50 to 100 ° C, 350 to 6000 ppm of calcium stearate and 300 to 5000 ppm of stearyl amide, adding 50 to 1500 ppm of silica and 200 to 1500 ppm of talc, Extruding the blend through a T dice, Preheating the extruded fabric at temperatures of 70-80 ° C. in the first and second rollers of the stretching apparatus, Stretching in the MD direction (length direction) in the third and fourth rollers of the stretching apparatus, In a fifth roller of the stretching apparatus, annealing at a temperature of 40 to 50 ° C., and In the sixth roller of the stretching apparatus, the method for producing a biodegradable MDO heat shrink film for labels, comprising the step of cooling to a temperature of 30 ~ 40 ℃. The method of manufacturing a biodegradable MDO heat shrink film for labels according to claim 6, wherein the speed ratio of the third and fourth rollers of the stretching apparatus is 2: 1 to 2:10.

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