KR100909776B1 - Biodegradable sheet for a heat constriction film - Google Patents

Abstract

The present invention has excellent biodegradability and heat shrinkability, and has the appropriate strength, printing, deposition, coating, lamination, so that it is not recycled, biodegradable sheet for heat shrinkable film used as a packaging material such as coating, binding, exterior, label Regarding the sheet, the biodegradable sheet for heat-shrinkable film of the present invention comprises 90.0 to 99.0 parts by weight of polylactic acid resin, 1.0 to 10.0 parts by weight of an impact modifier for PLA, and the sheet is 30 seconds in 90 ° C. hot water. When left to stand, the heat shrinkage rate is 10% or less in at least one direction of the sheet length direction and the width direction.

 Biodegradable sheet for heat-shrinkable film of the present invention constituted as described above is a sheet required for producing a heat-shrinkable film excellent in shrinkage using PLA as a main raw material, heat shrinkage rate, transparency, mechanical strength, As it possesses elongation, it is not only industrially practical to replace heat-shrinkable film made of raw materials of synthetic resin series, but also used by consumers when using eco-friendly PLA extracted from plant resources as main raw material. Fast biodegradation can prevent environmental pollution.

Description

Biodegradable sheet for a heat shrinkable film {Biodegradable sheet for a heat constriction film}

The present invention relates to a biodegradable sheet used to prepare a heat shrinkable film that can be used as a packaging material such as coating, binding, exterior, label, etc. More specifically, it has a good strength with good biodegradability and heat shrinkability It relates to a biodegradable sheet for heat-shrinkable film used as a packaging material that can not be recycled because of printing, deposition, coating, and lamination.

In general, synthetic plastics are used for various purposes all over the world as packaging materials that are indispensable for modern people because of their cheap and light properties along with their excellent properties. However, these conventional synthetic plastics have a problem that their advantages and disadvantages are not easily decomposed, and thus the environmental pollution problem is serious. Therefore, in recent years, countries have been interested in finding a solution. In the meantime, landfilling, incineration and regeneration have been mainly used, but these methods cannot fundamentally solve the environmental pollution problem, and thus are interested in the development of so-called degradable plastics, which make the plastics ready to decompose themselves. It is concentrated. Currently, various kinds of degradable plastics have been developed from various technologies and raw materials. Among them, polylactic acid (hereinafter referred to as "PLA") is inexpensively manufactured in large quantities by the fermentation method of L-lactic acid and decomposed under composting conditions. Its fast speed, resistance to mold, and good odor resistance to food are expanding its range of applications.

On the other hand, in the case of the heat-shrinkable film, coating, binding, or exterior of containers, plastic bottles, glass bottles, and various rod-shaped articles (pipes, rods, wood) and the like, in particular, a part of these caps, shoulders, barrels, or the like It is used for the purpose of covering the entire surface, marking, protecting, binding, and improving the value of the product.It is widely used in the field of integrated packaging such as boxes, bottles, plates, rods, and notebooks. It is true. Such shrink films are generally used to improve the image of the product, increase the advertising effect, increase the product protection effect by using a shrink film composed of materials such as vinyl chloride, polystyrene, polypropylene, polyester, and polyolefin. . However, since these films are used by various printing, deposition, coating, and lamination for the purpose, the used films are not recyclable and rely on disposal by incineration, causing problems of environmental pollution.

The present invention is to solve the problems of the conventional heat shrinkable film as described above, in particular to provide a sheet having a good biodegradability for producing a heat shrinkable film having good low-temperature shrinkage and biodegradability and excellent appearance uniformity after shrinkage For that purpose.

Biodegradable sheet for heat-shrinkable film of the present invention for achieving the above object;

Polylactide resin 90.0 to 99.0 parts by weight, PLA impact modifier 1.0 to 10.0 parts by weight, the sheet is left at 90 ℃ hot water for 30 seconds in the heat shrinkage rate of at least one direction of the sheet length direction and width direction 10 It is characterized by being below%.

According to another configuration of the present invention, the polylactic acid is obtained by polymerizing lactic acid, and the polylactic acid used in the present invention is composed of L-lactic acid, D-lactic acid or L, D-lactic acid, The number average molecular weight is more than 10,000. These polylactic acids may be used alone or in combination.

According to another configuration of the present invention, other additives may be added to the sheet, if necessary, up to 5.0 parts by weight of the total composition.

According to another configuration of the invention, the sheet is characterized in that the thickness of 0.15 ~ 1.20mm. Outside the above thickness range, it is not preferable because it is not suitable as a packaging material.

According to another configuration of the present invention, the PLA impact modifier uses a copolymer consisting of polyester or aliphatic polyester and polylactic acid, and the polyester used is ROOC-Ar-COOR '(here, R, R 'is hydrogen or an alkyl group) terephthalic acid, phthalic acid, isophthalic acid, naphthalene 2,6-dicarboxylic acid, diphenylsulfonic acid dicarboxylic acid, diphenylmethanedicarboxylic acid , Diphenyl ether dicarboxylic acid, diphenoxy ethane dicarboxylic acid, cyclohexane dicarboxylic acid, or a group consisting of alkylene esters thereof, or aliphatic dicarboxylic acid or derivatives thereof include ROOC (CH ₂ ) succinic acid, glutaric acid, malonic acid, oxalic acid, adipic acid, sebacic acid, azelaic acid, nonandi Carboxylic acids and their alkyl or Is at least one member selected from the group consisting of aryl ester derivatives, and glycols are ethylene glycol, 1,3-propanediol, 1 having a structure of HO- (CH ₂ ) n-OH (where n is an integer of 2 or more). Consists of 4-butanediol, 1,5-pentanediol, 1,6-hexanediol or propylene glycol, 1,4-cyclohexanediol, hexamethylene glycol, polyethylene glycol, triethylene glycol, neopentyl glycol, tetramethylene glycol 1,2-propanediol, 1,2-butanediol, 1,3, which are aliphatic dihydric alcohols capable of forming a branched structure represented by the group consisting of alkylene glycols and polyalkylene glycols, or the following general formula (1) -Butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexane Groups consisting of diols, 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 1,5-octanediol, 1,6-octanediol and the like can be used.

.... Formula (1)

In General Formula (1), R ₁ is an alkylene group of C ₂ to C ₈ , and R ₂ is an alkyl group of C ₂ to C ₈ .

The copolymer composed of aliphatic polyester and polylactic acid is a block copolymer, and the aliphatic polyester is an aliphatic dicarboxylic acid or a derivative thereof, and ROOC (CH ₂ ) nCOOR '(where R and R' is hydrogen or Alkyl group, and n is an integer of 2 to 14). Ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5- having ethylene glycol having a structure of HO- (CH ₂ ) n-OH (n is an integer of 2 or more) Alkylene glycol or polyalkylene glycol consisting of pentanediol, 1,6-hexanediol or propylene glycol, 1,4-cyclohexanediol, hexamethylene glycol, polyethylene glycol, triethylene glycol, neopentyl glycol, tetramethylene glycol Done with 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, which are aliphatic dihydric alcohols capable of forming a branched structure represented by the group or general formula (1), 1 , 3-pentanediol, 1,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,2-octanediol, 1, Groups consisting of 3-octanediol, 1,4-octanediol, 1,5-octanediol, 1,6-octanediol and the like can be used.

The other additives may be ether ester plasticizers, oxyacid esters or glycol plasticizers as plasticizers for the purpose of improving secondary processability. Specifically, ethylene glycol, propylene glycol, polyethylene glycol, sorbitol, glycerin (glycerol), Methoxypolyethylene glycol, tri-n-butyl citrate, and the like can be used. It is also possible to mix and use two or more types of these mixtures. As the nucleating agent, inorganic particles such as titanium dioxide including talc, silica, kaolin, calcium carbonate, alumina, zirconia, zeolite, etc. may be used. The inorganic particles used in the nucleating agent may be used in combination with an organic lubricant. An aliphatic hydrocarbon-based lubricant or an aliphatic amide-based lubricant may be used. In addition, a crosslinking agent is used for the purpose of lowering the melt tension during molding into a film. As a crosslinking agent that may be added to the present resin, an organic peroxide compound, a metal complex, an epoxy compound, an isocyanate compound, or the like may be used. In addition, depending on the application, a substance such as a sunscreen, an antibacterial / deodorant, a heat stabilizer, a light stabilizer, a flame retardant, an antistatic agent, an antioxidant, or a pigment may be used as an additive.

According to the configuration of the present invention, the content of the PLA impact modifier should be made of 1.0 to 10.0 parts by weight, which contains more than 10.0 parts by weight of the problem sharply worsened in terms of transparency, the content of the PLA impact modifier will be increased It is not preferable because it inhibits the crystallization of the sheet and increases the thermal contraction rate of the sheet. In terms of transparency and heat shrinkage, it is preferable not to use a PLA impact modifier. However, in this case, the EDGE of the sheet may be broken or the film may be broken when the sheet is not flexible. Since tearing may occur, it is required to use an appropriate amount of PLA impact modifier according to the thickness of the sheet, and the minimum use ratio is about 1.0 part by weight.

In addition, according to the configuration of the present invention, the thermal contraction rate of the sheet should be maintained at 10% or less in at least one direction of the sheet length direction and the width direction, the residual stress remaining in the sheet when the thermal contraction rate is greater than 10% in the sheet state This is because there is a problem in that the draw ratio must be made very high in the drawing process during film forming. If the final film is made without removing the residual stress, if the product is applied to the label, etc., if the label is put on the plastic bottle and passed through the hot air tunnel, excessive shrinkage will occur, causing problems such as shrinkage unevenness and end burn. . In order to maintain the thermal contraction rate of the sheet at 10% or less in at least one direction of the sheet length direction and the width direction, a driving roll that acts in the process from the die to the T / UP roll in the sheet extrusion process, in particular, casting It is important to properly maintain the rotational speed of the roll to prevent stretching.

According to the configuration of the present invention, the polylactic acid and PLA impact modifier and optionally additives are fed into a twin screw extruder (TWIN SCREW EXTRUDER) at a constant mixing ratio through a feeder and melt-extruded while removing moisture by high vacuum, It can be cooled and solidified to produce a biodegradable sheet required to produce a heat shrinkable film, which is stretched in either the longitudinal direction of the film or the width direction of the film, or bidirectionally stretched at an appropriate draw ratio. By making the biodegradable heat shrinkable film can be produced.

Biodegradable sheet for heat-shrinkable film of the present invention constituted as described above is a sheet required for producing a heat-shrinkable film excellent in shrinkage using PLA as a main raw material, heat shrinkage rate, transparency, mechanical strength, As it possesses elongation, it is not only industrially practical to replace heat-shrinkable film made of raw materials of synthetic resin series, but also used by consumers when using eco-friendly PLA extracted from plant resources as main raw material. Fast biodegradation can prevent environmental pollution.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to the following Examples. In addition, the characteristics evaluation method of the SHEET prepared according to the following Examples and Comparative Examples are as follows.

(1) heat shrinkage

The specimens were cut and sampled in a square shape to be 100 mm in the length direction and 100 mm in the width direction, and the samples were heat-treated in hot water at 90 ° C. for 30 seconds to measure the shrinkage rate, and the average value was repeated 20 times n times. Defined as.

(2) Transparency (HAZE: ASTM D 1003)

HAZE was obtained under ASTM D 1003 analysis conditions.

(3) Mechanical Strength (Tensile Strength; ASTM D 882)

Using a tensile tester, the temperature was measured at a tensile speed of 500 mm / min at a temperature of 20 ± 2 ° C and a relative humidity of 65 ± 2%, and the advancing direction of the sheet was expressed in MD and the width in TD.

(4) Flexibility (elongation; ASTM D 882)

The elongation until break of the sheet was determined under the same conditions as the tensile strength.

Example 1

Put 100.0kg of PLA resin of NW LLC into feeder and feed it into twin screw extruder that can melt-extrude while removing moisture by high vacuum. The discharged sheet was cooled and solidified in a casting roll to prepare a sheet having a thickness of 200 μm. Specimens were prepared from the prepared sheets to measure thermal shrinkage, transparency, mechanical strength, and flexibility, and the results are shown in Table 1 below.

Example 2

A sheet was prepared in the same manner as in Example 1 except that 5.0 kg of a copolymer made of NW LLC's 95.0 kg of PLA resin, a polybutylene succinate (PBS), and a polylactic acid (PBS-PLA COPOLYMER) was used. Shrinkage, transparency, mechanical strength, and flexibility were measured, and the results are shown in Table 1 below.

Example 3

The sheet was prepared in the same manner as in Example 1 except that 10.0 kg of a copolymer (PBS-PLA COPOLYMER) consisting of 90.0 kg of PLA resin of NW LLC and polybutylene succinate (PBS) and polylactic acid was used. Shrinkage, transparency, mechanical strength, and flexibility were measured, and the results are shown in Table 1 below.

Comparative Example 1

A sheet was prepared in the same manner as in Example 1 except that 15.0 kg of a copolymer (PBS-PLA COPOLYMER) consisting of 85.0 kg of PLA resin, polybutylene succinate (PBS) and polylactic acid, was used. Shrinkage, transparency, mechanical strength, and flexibility were measured, and the results are shown in Table 1 below.

Comparative Example 2

A sheet was prepared in the same manner as in Example 1 except that 20.0 kg of a copolymer (PBS-PLA COPOLYMER) consisting of 80.0 kg of PLA resin of NW LLC and polybutylene succinate (PBS) and polylactic acid was used. Shrinkage, transparency, mechanical strength, and flexibility were measured, and the results are shown in Table 1 below.

division Composition (wt%) Heat shrinkage (%) HAZE (%) Tensile Strength (㎏ / ㎠) Elongation (%) PLA PBS-PLA Copolymer MD TD MD TD MD TD Example-1 100 - 4.5 0.9 0.7 5.2 5.3 4.6 3.9 Example-2 95 5 6.9 1.5 4.8 5.1 5.0 7.8 6.9 Example-3 90 10 8.5 1.9 6.9 5.1 5.1 9.2 9.8 Comparative Example-1 85 15 10.9 2.4 15.6 4.7 4.8 13.0 12.0 Comparative Example-2 80 20 13.1 2.9 23.9 4.5 4.5 15.2 14.8

Claims (5)

Polylactide resin 90.0 to 99.0 parts by weight, a copolymer of polybutylene succinate (PBS) and polylactic acid (PBS-PLA COPOLYMER) is composed of 1.0 to 10.0 parts by weight, the sheet for 30 seconds in 90 ℃ hot water When left untreated, the heat shrinkage rate is 10% or less in at least one direction of the sheet length direction and the width direction, and the biodegradable sheet for heat shrinkable film. The method of claim 1, wherein the polylactic acid is obtained by polymerization using L-lactic acid, D-lactic acid or lactic acid (Lactic acid) consisting of L, D-lactic acid, alone or in combination, the number average molecular weight of 10,000 or more A biodegradable sheet for heat shrinkable film, characterized in that. delete The biodegradable sheet for heat shrinkable film according to claim 1, wherein the sheet has a thickness of 0.15 to 1.20 mm. A packaging material comprising the biodegradable sheet for heat-shrinkable film according to claim 1.