KR100322376B1 - Sunblocking, shrinkable film composition - Google Patents

Abstract

PURPOSE: Provided is a sunblocking, shrinkable film composition which can maintain freshness of food and extend a conservation period, and be used for producing a food container or packing shrinkable film, and can contribute to cost reduction. CONSTITUTION: The composition comprises 3-7 wt% of sunblocking agent, which is at least one selected from 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 0.01-0.02 wt% of non-ionic antistatic agent and the rest of polyethylene resin. The shrinkable film produced from the composition can effectively block a harmful ultraviolet, and finely maintain freshness of food and thus extend a conservation period of food.

Description

Shrink Film Composition for UV Protection

The present invention relates to a resin composition used in the manufacture of food containers or shrink packaging films, and more particularly, it is possible to maintain the freshness of foods, to extend the shelf life, and to shrink the UV-protective shrink film composition that can contribute to cost reduction. It is about.

In general, the organic material is aged and degraded by ultraviolet (Ultra Violet), which is about 1% of the sunlight reaching the surface of the earth, the wavelength is shorter than visible or infrared light.

Ultraviolet rays can be classified into the wavelength range of the ultraviolet rays A (320 ~ 400nm), ultraviolet B (280 ~ 320nm), ultraviolet C (200 ~ 280nm), ultraviolet C region is the most energy of the ultraviolet rays, but most of the ozone layer It does not reach the ground surface because it is removed by the ultraviolet ray, the ultraviolet ray B region is a region that can cause burns caused by sunlight, and the ultraviolet ray A region serves as one cause of aging and deterioration.

Because of the high energy of ultraviolet rays, they activate various chemicals to change their structure or paralyze their functions. In particular, organic pigments, which are frequently used in household goods, are easily lost or lost as they are activated by increasing or decreasing them.

Therefore, in the case of a container or a transparent object of household goods, if it is made of a resin film containing UVA or surface treatment or surface treatment, it absorbs harmful ultraviolet rays of 320-400nm and converts it into harmless thermal energy to generate heat of reradiation. The object can be protected, and the sunscreen itself has a property of self-reducing so that it does not deteriorate.

Therefore, when a sunscreen is added to a container for an article such as foods, beverages, alcoholic beverages, general merchandise, clothing, and cans, resins, fertilizers, building materials, and various integrated condensates, a sunscreen is added to the film, and the physical properties of the article are These branches can prevent various destructive phenomena that can be transformed by ultraviolet rays such as taste and aroma, can extend the shelf life, improve the long-distance transportation method, and fish and seafood that must be packaged with hard to recycle Schiropol. It can be used as a packaging material, and can replace aluminum cans that depend only on imports, thus contributing to cost reduction.

The present invention has been made through the above process, it can maintain the freshness of the food, can extend the shelf life, shrinkage film for UV protection which can be used for the production of food container or packaging shrink film material that can contribute to cost reduction The purpose is to provide a composition.

1 is a view schematically showing a resin film manufacturing apparatus,

2 is a view showing the UV shielding rate of a film prepared by changing the concentration of the sunscreen and the film thickness,

3 is a view showing the ultraviolet transmittance of a film produced by changing the concentration of the sunscreen and the film thickness.

Explanation of symbols on the main parts of the drawings

1: extruder 2: die 5: pinch roll

Shrink film composition for ultraviolet protection of the present invention for achieving the above object, 2- (2'-hydroxy-5'methylphenyl) benzotriazole and 2- (2'-hydroxy-5'-t-butylphenyl ) 3-7% by weight of sunscreen selected from benzotriazole, at least one of 0.01-0.02% by weight of nonionic antistatic agent, and polyethylene resin.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments.

First, the shrink film composition of the present invention is prepared in the following composition, the resin used in the present invention mainly uses a polyethylene (Polyethylene: PE) resin, but a polyolefin (Polyolefin) resin, polypropylene (Polypropylene) resin, nylon ( Nylon resin can also be used.

Polyethylene (PE) resin is a transparent or semi-transparent solid that has excellent resistance to acids, alkalis and solvents, and has excellent electrical insulation, water resistance, moisture resistance, and cold resistance, so as to cover various containers or wires, pipes, fibers, linings, and packaging materials. It is used for most shrink film or LLD film for food packaging.

In addition, the sunscreen agent can be roughly divided into organic and inorganic, and the organic sunscreen is also divided into salicylate (Salycylate), benzophenone (Benzophenone), cyanoacrylate (Cyanoacrylate).

Organic sunscreens that can block ultraviolet rays (360-380 nm) in areas that modify the flavors and flavors of food and drink are called lowilit-26 of benzotriazole-based organic blockers. Inorganic sunscreens are difficult to use due to the whitening phenomenon that the transparency is significantly lowered and the additive is released over time.

The sunscreen agent called lowilit-26 of the benzotriazole type added to the composition of the present invention has the following properties.

-Structural formula

-Chemical name

① 2- (2'-hydroxy-3'-t-butyl-5'methylphenyl) -5-chlorobenzotriazole

② 2- (2'-hydroxy-5'methylphenyl) benzotriazole

③ 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole

Molecular weight: 315.8

CAS number: 3896-11-5

In addition, the sunscreen has the following physical properties.

Melting Point: 137∼142 ℃

Flash point: 232 ℃

-Solubility (grams per 100 ml of solvent at room temperature) is shown in Table 1.

TABLE 1

Such sunscreens are pale yellow crystals, odorless, and have a purity of 99% or more. In addition, the results of the characteristic test are shown in Table 2 below.

TABLE 2

In the present invention, in addition to the sunscreen as described above, a nonionic antistatic agent is added at 0.01-0.02% by weight.

Because of the toxicity and thermal stability of plastics, only nonionic antistatic agents can be used without cationic or anionic antistatic agents.

This nonionic antistatic agent is added to remove the chargeability of the produced shrink film or LLD film for food packaging.

Next, a process of manufacturing a shrink blocking film for ultraviolet rays using the shrink film composition having the above composition will be described. As an example, a shrink film manufacturing process will be described, but the same may be used for a food packaging LLD film.

On the other hand, the shrink film is used to heat-stretch the resin to produce an oriented film and to re-heat to a temperature above the softening point to relieve the stress inherent in the resin film, to firmly package the article using the shrinkage characteristics of the film.

Such shrink films require low temperature shrinkage to shrink at the lowest possible temperature and time preservation to shrink in the shortest possible time, and to maintain the shrinking property and the contracted force in a wide range of silver.

In general, the most important physical property of the shrink film made of polyethylene resin is the shrinkage, the longitudinal shrinkage (MD) of 70 to 80%, the transverse shrinkage (TD) of 15 to 20% is required, the balance adjustment according to the conditions This is possible.

As described in KS A 1511, the shrinkage measurement method is immersed in a film of 10 cm in width and length in glycerine at 120 ° C. for 20 seconds and then immersed in cold water for 10 seconds and then taken out.

In addition, shrinkage rate is calculated | required as follows.

Shrinkage (%) = {First Length (10㎝)-Measuring Length} / First Length (10cm) × 100

This shrinkage is mainly determined by the manufacturing apparatus, the transverse shrinkage rate (TD) is represented by the Blow Up Ratio (BUR), and the longitudinal shrinkage rate (MD) is represented by the Draw Down Ratio (DDR). And then look like this:

Expansion ratio (B.U.R) = film width × 2 / 3.14 × die diameter

D.D.R = Die Lip Width / Expansion Ratio × Film Thickness

Cofactors for determining the shrinkage rate are the state of the resin and processing conditions, and generally depend on the melt index, density, molding temperature, winding speed, freezing line height, and screw speed. Bar, I learned the following facts.

The relationship with the melt index is shown in Table 3.

As can be seen from the table below, the longitudinal shrinkage is 76-78% with little change, but the horizontal shrinkage gradually decreases as the melt index increases. Therefore, it can be seen that the preferred melt index range is 4g or less per 10 minutes.

TABLE 3

As a result of experimenting the relationship between the density and the shrinkage ratio, as shown in Table 4, both the horizontal shrinkage rate and the longitudinal shrinkage rate are decreased as the density increases, but it can be seen that the density range is less than 0.921 g / cm 2 in a good range.

TABLE 4

In addition, the correlation between the extrusion temperature and the shrinkage rate, as shown in Table 5, it can be seen that the shrinkage slightly decreases as the extrusion molding at a high temperature, which is a significant improvement in the optical properties of the film itself, the temperature of the freezing line It seems to be due to the increase. In other words, as the melting temperature increases, the melt index is more uniformly diffused, the density increases and shrinkage is suppressed.

Thus, it can be seen that a good extrusion temperature is 160 ~ 180 ℃.

TABLE 5

Next, the relationship between expansion ratio and shrinkage ratio is shown in Table 6. The expansion ratio refers to the ratio of the film width to the diameter of the die. When the expansion ratio increases, the longitudinal shrinkage decreases but the horizontal shrinkage increases inversely. This is because the molecular orientation in the transverse direction increases as the expansion ratio increases. As can be seen from Table 6, it can be seen that a good expansion ratio is 1.5 to 2.5.

TABLE 6

On the other hand, the drawability (DDR) is a measure of how fast the take-up speed can be measured as a measure of how long the film bubble is stretched in the longitudinal direction when the shrink film is extruded. As can be seen that the greater the drawability increases the longitudinal shrinkage, it can be seen that the good range is 4-6.

In addition, as shown in Table 8, as the molten resin leaving the die solidifies into the bubble film, the relationship between the freezing line and the shrinkage rate is determined. It can be seen that the lower the height of the freezing line, the less the flow of cooling air is given a time margin to prevent the non-uniformity of the film surface generated in the die shrinkage ratio by that much. This freezing line is highly related to the cooling rate and cooling temperature, and it can be seen that a good freezing line height is 40 to 60 cm.

TABLE 7

TABLE 8

Therefore, the optimum manufacturing conditions that can exhibit the required shrinkage rate identified through the above data, the melt index is 4g or less per 10 minutes, the density is 0.921g / ㎠ or less, the molding temperature in the extruder 160 ~ 180 ℃ It was found that the expansion ratio in the die was 1.5 to 2.5, the freezing line was cooled to 40 to 60 cm from the die, and the winding speed in the winder was adjusted to produce 4 to 6 so as to produce the drawability.

As such, the UV blocking shrink film manufacturing process of the present invention to which the process conditions recognized through the experiment is applied is one of the general compression processes as shown in FIG. 1, but the conditions of the manufacturing process are specially given in the present invention. M / B containing solid resin, sunscreen, antioxidant, and nonionic antistatic agent were mixed in a cylindrical container, and the melt was adjusted to 4g or less per 10 minutes and the density was 0.921g / cm2 or less. Next, the molten resin mixture is continuously extruded at a temperature of 160 to 180 ° C. in a tube shape through the die 2 as the screw is rotated in the extruder 1, and then the height of the freezing line 3 is 40 to 60 cm from the die. Compressed air (4) is injected into the tube so as to be positioned in the tube to extend in the horizontal direction so that the expansion ratio is 1.5 to 2.5, and at the same time in the longitudinal direction through the pinch rolls (5) so that the pullability is 4 to 6. By stretching it comprises a configuration for producing the shrink films for UV protection.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

In the present embodiment, a polyethylene (PE) resin was used as the resin, and a sunscreen agent used Lowilit-26 based on benzotriazole. As shown in Table 9, the polyethylene (PE) resin composition was changed while changing the amount of the sunscreen. After manufacturing a shrink film by varying the thickness of each of the UV shielding rate was tested.

In this experiment, the UV shielding rate was measured by using an ultraviolet spectrometer. As a result of the experiment, as shown in FIG. 1, the shielding rate increases as the amount of sunscreen increases and the thickness increases. % Is the most suitable, and it can be seen that the thickness is most suitable 90 ~ 100μ.

TABLE 9

Example 2

In this embodiment, after producing the shrink-blocking film for UV protection in the same composition as in Example 1, the transmittance was measured by performing a UV transmission experiment of 360 ~ 380nm wavelength range which is required in the natural beverage market. As a measuring instrument, an ultraviolet spectrometer (Ultraviolet-Spectrometer) was used.

According to the measurement results, as shown in Table 10, the thicker the thickness, the higher the concentration, the transmittance can be reduced to less than 1%, but in consideration of economics, the concentration is most suitable, the thickness is 90 ~ 100μ It can be seen that this is most suitable.

TABLE 10

As described above, the use of the shrink film made of the shrink-protecting film composition of the present invention can effectively block harmful ultraviolet rays when used as a food container such as food, beverages, etc., so that the freshness of food and the like can be kept well and the shelf life It can be used as a packaging material for fish and seafood to replace Schiropol, which is difficult to recycle, to improve long-distance transportation, and to replace the imported aluminum cans. Useful effects such as cost reduction are obtained.

Claims (1)

3-7% by weight of at least one sunscreen selected from 2- (2'-hydroxy-5'methylphenyl) benzotriazole and 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole; , 0.01-0.02% by weight of a nonionic antistatic agent, and a shrink-proof composition for UV blocking, characterized in that it contains a polyethylene resin as a remainder.