KR100206417B1 - Antibacterial polypropylene resin sheet - Google Patents

Abstract

The present invention relates to an antimicrobial polypropylene resin sheet, wherein the propylene resin, the low molecular ethylene resin, and all or part of the surface, or the entire surface in the pores, comprise metal ion-coated porous inorganic particles. The antimicrobial polypropylene resin sheet according to the present invention has excellent transparency, blocking resistance, and the like, and is easy to process and has excellent antimicrobial properties, and thus has antibacterial activity such as decorative interior papers, high-grade cases, as well as food packaging materials, medical devices, and medicines. It can be very usefully used as a packaging material or a case for an article required.

Description

Antibacterial polypropylene resin sheet

The present invention relates to an antimicrobial polypropylene resin sheet, and more particularly, good blocking resistance, transparency and the like, not only easy processing but also excellent antimicrobial properties, as well as various packaging materials, stationery and interior decoration, as well as food packaging materials The present invention relates to an antimicrobial polypropylene resin sheet applicable to applications requiring antimicrobial activity.

As a plastic container for storing frozen foods, powdered foods, fish, etc. fresh for a long time, and various stationery, office supplies, electrical appliances, tools, toys, etc. requiring multifunctionality, polystyrene sheets, polyvinyl chloride sheets, poly Terephthalate sheets, polyolefin sheets and the like.

Of these, polystyrene sheets have good transparency and mechanical properties, but not only cause various diseases due to odors generated during the manufacturing process, but also because of the low cost of resins, there is a limit to general use. In addition, there is a problem that it is an environmentally harmful substance that generates black smoke and dust during incineration.

On the other hand, polyvinyl chloride sheets are transparent and inexpensive, and thus economical. However, polyvinyl chloride sheets generate environmental problems like polystyrene sheets because they generate harmful chlorine gas upon combustion.

An alternative resin that can overcome these problems is the polyolefin resin, which is particularly popular among polyolefin resins. In particular, the polypropylene resin has a light density of 0.90-0.92 g / cm 3, and is excellent in heat resistance, electrical insulation, chemical resistance, workability and bending resistance, and is harmless. It is non-toxic and its range of use and use are rapidly diversifying and widening.

Usually, a polypropylene resin is a copolymer of ethylene and other olefinic monomers, and it is divided roughly into a homopolymer, a random copolymer, and an amp copolymer according to the presence or absence of copolymer addition. It is pointed out that the double homopolymer has excellent crystallinity and stiffness and high melting point while poor transparency, and the random copolymer has better transparency than the homopolymer but has poor crystallinity, melting point and stiffness. . In contrast, impact copolymers have been recognized for their excellent impact resistance. Therefore, it is possible to obtain a resin having more preferable physical properties by mixing and using according to the purpose of use and process characteristics.

By the way, the sheet made of polypropylene resin has a disadvantage that the transparency is inferior to the conventional polystyrene resin sheet, polyvinyl chloride resin sheet is required to improve this. In addition, since the polypropylene resin sheet is applied to not only food packaging materials but also various packaging materials and containers requiring hygiene or antibacterial in hospitals or the like, improvement of antibacterial properties is also urgently required.

Transparency of the polypropylene resin may be achieved by modification of the resin itself, but this method alone is limited, and may be achieved by a method of controlling the molding apparatus and process conditions in sheet forming. The core of this method is to provide transparency by suppressing crystal formation through the quenching process. Generally, a quenching method using a cooling roll is used, but the cooling effect is limited. Recently, a quenching method through a cooling water is mainly used. It is adopted.

In addition, when the polypropylene resin sheet is used for applications requiring antimicrobial properties such as packaging containers of various foods, ethylene gas generated from plants such as vegetables, nitrogen oxides generated from decay of animal matter, ammonia, phosphoric acid, etc. It is important to prevent the growth of microorganisms such as bacteria by removing them. To this end, an antimicrobial agent is added. Examples of such additives include an inorganic antimicrobial agent mainly composed of an inorganic compound and an organic antimicrobial agent mainly composed of an organic compound. Among them, organic antimicrobial agents are difficult to be widely used because they are likely to be harmful to the human body due to the nature of the components, have poor thermal stability, and generate odors during decomposition. In contrast, inorganic antimicrobials are generally preferred because they inhibit some of the properties of plastic products but are harmless.

As an example of research on such an antimicrobial agent, Japanese Patent Laid-Open Nos. 63-86757, 2-101003, 2-247059, and 4-21614 use inorganic fine particles to maintain the freshness of vegetables. Japanese Patent Application Laid-Open No. 1-207339 has suggested a method of providing antibacterial and deodorizing properties using an adsorbent inorganic material. However, this conventional technique is limited in that it can be applied only to stretched films or simple injection products. That is, it is impossible to apply this conventional technique to the production of antimicrobial polypropylene resin sheets having high crystallinity.

It is an object of the present invention to provide an antimicrobial polypropylene resin sheet that is easy to process and has transparency and antimicrobial activity.

The technical problem of the present invention is a) a propylene resin having a melting index of 1 to 20 g / 10 minutes and a melting temperature of 130 to 180 ° C., and b) a low molecular ethylene having a melting index of 20 to 40 g / 10 minutes and a melting temperature of 90 to 130 ° C. And c) an average particle diameter of 0.1 to 5 mu m and all or part of the surface or the entire surface of the pores comprises metal ion-coated porous inorganic particles, wherein a), b) and c) are each 85. It can be made by an antimicrobial polypropylene resin sheet characterized in that it comprises ~ 99.89 parts by weight, 0.01 to 5 parts by weight and 1 to 10 parts by weight.

In the antimicrobial polypropylene resin sheet according to the present invention, the propylene-based resin is 95-99.99 mol% of propylene, at least one olefin selected from ethylene or butene other than propylene is preferably 0.01-5 mol%, such propylene Examples of the system resins include propylene-ethylene copolymers, propylene-butene copolymers, and propylene-ethylene-butene copolymers.

In addition, examples of the low molecular weight ethylene-based resin may include high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene-vinylacetate copolymer and the like, and the content thereof is preferably within the above range. If the content of the low molecular weight ethylene copolymer is less than the above range, the effect of the invention cannot be obtained. If the content of the low molecular weight ethylene copolymer exceeds the above range, uniform kneading with the propylene-based resin is difficult, so that bubbles and / or die lines or the like are formed on the surface of the sheet. This results in poor appearance and excessive surface transition of the low molecular resin, resulting in adhesion to the belt surface or friction between sheet mirror surfaces.

On the other hand, all or part of the surface of the porous inorganic particles, or the electric surface in the pores by coating a predetermined thickness with a metal ion excellent in the adsorption decomposition ability, such as silver, copper, zinc, etc. can obtain a desired antibacterial effect. That is, the metal ion-coated porous inorganic particles may exhibit more preferable antimicrobial activity by sterilizing action by active oxygen generated by itself, gas adsorption and decomposition action by metal ions.

Examples of porous inorganic particles that can be used include alumina, silica, zeolite, talc or kaolin, which are composed of stable components such as Al and Si, and have good light resistance and have a far infrared effect of 90% or more at 40 ° C. And the dispersion state between the particles is also good and those having a predetermined sterilization and antibacterial effect.

On the other hand, the average particle diameter and content of the metal ion-coated porous inorganic particles are very important factors in determining the effect of the present invention. First, the average particle diameter is preferably 0.1-5 탆, more preferably 0.5-3 탆. If the average particle diameter is less than the above range, the aggregation phenomenon of the fine particles is intensified, and the surface gloss or transparency is lowered. On the contrary, if the average particle diameter is exceeded, the sheet surface is not only rough but also has a problem in the process of rapidly increasing the filter pressure during extrusion. In addition, if the content is less than the above range, the antibacterial effect is insignificant, while if the content exceeds the above range there is a problem that the mechanical properties such as strength is lowered.

On the other hand, in the metal ion-coated porous inorganic particles, the coating amount of the metal ion is preferably 100-1,000 ppm.

The antimicrobial polypropylene resin sheet according to the present invention may further include known additives, for example, antistatic agents, dispersants, slip agents, antioxidants, ultraviolet stabilizers, etc. within a range that does not impair the effects of the present invention. .

Looking at the method for producing an antimicrobial polypropylene resin sheet according to the present invention, first, the propylene-based resin, the low molecular weight ethylene-based resin and the metal ion-coated porous inorganic particles having the above-described physical properties are taken and mixed as described above. The resin mixture was extruded under the conditions of 100-150 screw rpm at an extrusion temperature of 200-270 ° C. and an extrusion rate of 250-300 kg / h, followed by cooling to keep the extruded melt sheet at 15-40 ° C. It can manufacture by passing through a roll and quenching. At this time, when the cooling temperature is less than 15 ℃ excellent transparency, but the reverse winding phenomenon is difficult to form efficiently, on the contrary, at a temperature above 40 ℃ it is not preferable because the surface crystals may be too large and brittle. .

The resin mixture may be dry mixed or melt mixed, but melt mixing is preferred to ensure uniform and sufficient mixing.

The antimicrobial polypropylene resin sheet of the present invention can be produced by any existing molding machine, but it is particularly preferable to use a triangular (Δ) type belt type sheet molding machine.

On the other hand, transparency, which is one of the physical properties required as a polypropylene resin sheet, has a close relationship with high glossiness of the sheet surface. To this end, the sheet surface is mirror-finished so as to be in close contact with the surface of the roll or belt in contact with the sheet. Sufficient transcription and crystal formation inhibitory effects should be obtained. For this purpose, the resin must be molded into sheets while inducing a pooling phenomenon (banking phenomenon) of the resin.

However, when the surface of the sheet is excessively hardened, a blocking phenomenon occurs between sheets and the glare caused by the reflection of the surface is too large to easily cause sheet defects. can do. In this case, the shape, unit surface area and depth of the unevenness can be variously selected depending on the use of the sheet to be produced.

In this invention, it is preferable that a unit plane area is 1-500 micrometer <2> and depth 0.1-5.0 micrometers, and the space | interval between each shape is 0.01-0.1 mm. In addition, the shape of the irregularities may be formed in various shapes such as pyramid, diamond, cone, sphere, ellipse, etc., embossed or intaglio, it is more effective to give a complex shape having irregularity than the same shape.

The surface of the sheet is embossed by reheating the sheet using a roll embossed with such irregularities. In this case, the reheat treatment conditions may be carried out repeatedly one or several times at a temperature of 50-70 ° C. and a pressure condition of 1-10 kgf / cm 2. If the temperature is lower than 50 ℃ is difficult to transfer the shape to the sheet surface, on the contrary, if the temperature exceeds 70 ℃, the phenomenon that the resin sticks to the roll occurs, it is rather undesirable because it may damage the surface gloss.

The antimicrobial polypropylene resin sheet of the present invention prepared according to the preparation method as described above has surface crystals having a size of 250-500 mm 3 and the surface crystallinity is 60-80%. Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

First, a method for evaluating various performances of sheets prepared according to Examples and Comparative Examples of the present invention is described below:

1) Crystallinity

Using a density gradient tube consisting of carbon tetrachloride and normal heptane, the density (χ) was measured by an up-and-down method under a temperature condition of 25 ?? and then calculated by the following equation.

2) crystal size

The diffraction intensity of each angle was measured using an X-ray diffractometer (model name: D-MAX3C) of PCGAKU, and then the crystal size was calculated.

3) glossiness

It was measured using a glossiness meter (model name: GC-4010) of Gardner Neotek (USA) (reference diameter: black diameter, measuring strength: 60 degrees).

4) Surface Roughness

Measurement was carried out under a condition of cutoff 2.0 mm and stylus 2u using a contact type two-dimensional surface roughness measuring instrument (model name: SE-30D) manufactured by Kosaka Corporation (Japan).

5) Blocking resistance evaluation

A surface friction tester (model name: 2227001) of Seisaku-sho Co., Ltd. (Japan) was used to measure the static friction coefficient under conditions of a load of 1.0 kg and a speed of 150 mm / min to evaluate the blocking resistance therefrom.

6) Antimicrobial Evaluation

Using the Escherichia coli (ATCC 25922) as a strain, the test bacteria were brought into contact with the specimens, and then cultured for 24 hours at 25 ° C., followed by counting the bacteria to evaluate the antimicrobial activity.

Example 1

100 g of a homopolypropylene resin having a melt index of 2 g / 10 min and a melting temperature of 160 ° C., 1.5 g of low density polyethylene having a melt index of 20 g / 10 min, and 6 g of porous silica particles (average particle diameter: 2 μm) coated with copper ions Mixing produced a resin mixture. The obtained resin mixture was extruded at the speed | rate of 270 kg / h under the conditions of extrusion temperature 210 degreeC, and screw rpm 120, and the molten sheet was produced. The molten sheet was cooled on a 30 ° C. cooling roll, rotated at a speed of 20 m / min, and molded into a belt to obtain a sheet having a thickness of 200 μm.

Next, a pyramid embossed shape having a unit surface area of 250 µm ² and a height of 4 µm was embossed at intervals of 0.07 mm before final winding of the obtained sheet, at a temperature of 60 ° C. and 4 kgf / cm 2. Reheat treatment was performed under pressure conditions.

The antimicrobial polypropylene resin sheet thus prepared was evaluated for crystallinity, crystal size, glossiness, surface roughness, blocking resistance, antimicrobial properties, and the like by the method described above, and the results are shown in the following table.

Example 2-5

Using the same production method as in Example 1, the sheet was prepared by changing the production conditions within the scope of the present invention as shown in the following table. Evaluation of the obtained sheet was also carried out according to the same method and criteria for the same items as in Example 1, and the results are shown in the following table.

Comparative Example 1-5

The sheet was prepared using the same production method as in Example 1, but changing the production conditions to be outside the scope of the present invention as shown in the table below. Evaluation of the obtained sheet was also carried out according to the same method and criteria for the same items as in Example 1, and the results are shown in Table 1 below.

Since the antimicrobial polypropylene resin sheet according to the present invention has excellent transparency, blocking resistance, etc., it is easy to process and has excellent antibacterial properties, such as decorative interior papers, high-grade cases, as well as food packaging materials, and antimicrobial activities such as medical equipment and medicines. It can be very usefully used as a packaging material or a case for an article that requires.

Claims (5)

a) a propylene resin having a melt index of 1 to 20 g / 10 minutes and a melting temperature of 130 to 180 ° C., b) a low molecular ethylene resin having a melt index of 20 to 40 g / 10 minutes and a melting temperature of 90 to 130 ° C., and c) The average particle diameter is 0.1 to 5 탆, and all or part of the surface or the electric field in the pores includes metal ion-coated porous inorganic particles, wherein a), b) and c) are 85 to 99.89 parts by weight, respectively. -5 weight part and 1-10 weight part are contained, The antimicrobial polypropylene resin sheet characterized by the above-mentioned. The antimicrobial polypropylene resin sheet according to claim 1, wherein the propylene resin is selected from the group consisting of propylene-ethylene copolymers, propylene-butene copolymers and propylene-ethylene-butene copolymers. The antimicrobial polypropylene resin sheet according to claim 1, wherein the low molecular ethylene resin is selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene and ethylene-vinylacetate copolymer. The antimicrobial polypropylene resin sheet according to claim 1, wherein the porous inorganic particles are selected from the group consisting of alumina, silica, zeolite, talc and kaolin. The antimicrobial polypropylene resin sheet according to claim 1, wherein the metal ion in the metal ion-coated porous inorganic particle is silver ion, copper ion or zinc ion, and its coating amount is 100 to 1,000 ppm.