KR102687663B1 - Manufacturing method of recycled polypropylene film - Google Patents

Abstract

The present invention relates to a method of manufacturing a recycled polypropylene film, and more specifically, the method of manufacturing a recycled polypropylene film includes the steps of preparing a transparent plastic recycled raw material; Adding additives to the recycled raw material and extruding it; cooling the extrudate; and drying the cooled extrudate at a drying temperature of 160° C. to 180° C. and a drying time of 3 hours to 5 hours; It includes, and the drying step may be to maintain the moisture content of the extrudate at 0.2% or less.

Description

{MANUFACTURING METHOD OF RECYCLED POLYPROPYLENE FILM}

It relates to a method for manufacturing recycled polypropylene film according to embodiments of the present invention.

The global plastic recycling market is estimated at approximately KRW 59 trillion in 2022, of which the packaging material recycling sector amounts to approximately KRW 12 trillion as of 2019. The domestic plastic recycling market has shown an average annual growth rate of about 6% since 2019, and is expected to grow to about 2.6596 trillion won in 2026. With the continued growth of the plastic recycling market size, the quality of the recycled materials (i.e. plastic recyclables) obtained from the recycling process becomes an important factor. However, transparent plastic recycled materials have a problem in that physical properties such as transparency and strength are weakened after recycling.

In particular, PET (polyethyleneterephthalate) sheets or PP (polypropylene) sheets are made into a plate shape by melting and extruding PET or PP resin. Due to their excellent transparency and mechanical properties, they are widely used in various packaging materials and display purposes, but as the recycling rate increases, There are cases where transparency or strength decreases (i.e., the intrinsic viscosity (IV: Intrinsic Viscosity) value decreases), which results in haze phenomenon (decreased transparency), blooming phenomenon (fabric turns white), and transmittance. There is a problem with the falling phenomenon occurring. PET raw materials recycled from waste PET sheets have an IV that falls to the level of 0.68 to 0.75, are not uniform and have significant deviations, and the physical properties are deteriorated due to a decrease in molecular weight due to hydrolysis during the molding process of recycled PET, and the quality of the recycled PET product is poor. Problems may arise.

Accordingly, the present invention provides a method for producing a recycled plastic film, which can reduce the degradation of the properties (e.g., IV value, haze, and light transmittance) of transparent plastic recycled materials (e.g., PET, PP) and provide high-quality transparent plastic recycled products. is to provide.

KR10-0578766B1 KR10-0895529B1

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing recycled polypropylene film, which can secure strength and transparency by designing a recycling process and input of additives into recycled raw materials of waste transparent plastic, and a method for producing a recycled polypropylene film obtained by the above method. To provide recycled polypropylene film.

However, the problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to one embodiment, a method of manufacturing a recycled polypropylene film includes preparing a transparent plastic recycled raw material; Adding additives to the recycled raw material and extruding it; cooling the extrudate; and drying the cooled extrudate at a drying temperature of 160° C. to 180° C. and a drying time of 3 hours to 5 hours; It includes, and the drying step may be to maintain the moisture content of the extrudate at 0.2% or less.

According to one embodiment, the additive includes a glass bead, the glass bead includes borosilicate glass, soda lime glass, or both, and the glass bead includes a hollow glass sphere. Glass Sphere, Glass Sphere, or both, the glass beads are included in an amount of 0.2 parts by weight to 3 parts by weight based on 100 parts by weight of the recycled raw material, and the size of the glass beads is 50 micrometers to 10 micrometers. It may be nanometer.

According to one embodiment, the glass bead may include a glass bead surface coated with a polysiloxane-based resin or an ionic liquid; It further includes, wherein the polysiloxane-based resin is coated in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the glass beads, and the glass beads surface coated with the polysiloxane-based resin are coated in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the recycled raw material. It may be included in 3 parts by weight.

According to one embodiment, the additive further includes a polysiloxane-based resin, an ionic liquid, or both, and the polysiloxane-based resin has a molecular weight of 1,000 to 50,000 (g/mol), a viscosity of 100 cSt to 3,000 cSt, and a viscosity of 0.95 g/mol. It has a density of ml to 1.07 g/ml, and the polysiloxane-based resin and the ionic liquid each contain 0.1 to 2 parts by weight based on 100 parts by weight of the recycled raw material, and the ionic liquid is dodecylpyridinium. One selected from the group consisting of hexafluorophosphate (KOEI), lithium bistrifluoromethanesulfonimide (3M), and tri-n-butylmethylammonium bis-(trifluoromethanesulfonyl)imide (3M) Or it may include two or more types.

According to one embodiment, the extrudate is a transparent polypropylene recycled sheet, the extrudate has a haze of 5% or less, a light transmittance of 85% or more, and an IV (intrinsic viscosity, dL/g) of 0.7 to 1.5. It could be.

The present invention relates to a method for manufacturing a recycled polypropylene film, which can prevent a decrease in intrinsic viscosity value while maintaining light transmittance and haze, and provide a recycled product with excellent strength and transparency. The method for producing a recycled polypropylene film of the present invention can provide recycled transparent plastic products that can be applied not only to packaging materials and containers, but also to optical and display products by recycling waste transparent plastic.

Hereinafter, the recycled polypropylene film manufacturing method and the recycled plastic film of the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples and drawings.

According to one embodiment, the method for producing a recycled polypropylene film of the present invention includes preparing a transparent plastic recycled raw material; Adding additives to recycled raw materials and extruding them; cooling the extrudate; and drying the cooled extrudate; may include.

According to one embodiment, the step of preparing the transparent plastic recycling raw material is preparing the recycled raw material obtained from waste transparent plastic, wherein the waste transparent plastic is polyethyleneterephthalate (PET) or polypropylene (PP). ) It may be a transparent sheet, film, beads, transparent PET, etc.

According to one embodiment, the step of preparing the transparent plastic recycling raw material includes selecting and pulverizing the transparent plastic to obtain transparent plastic flakes; Dehumidifying and drying the transparent plastic flakes; Primary grinding of transparent plastic flakes; Secondary grinding the first grinded pulverized material; Crystallizing the secondary grinded product; and pelletizing; may include.

According to one embodiment, the step of obtaining the transparent plastic flakes includes selecting waste transparent plastic from plastic waste, removing contaminants (thin film layer, adhesive layer, etc.), labels, etc., and disposing waste transparent plastic with a size of 1 mm to 3 mm. After cutting and pulverizing the waste transparent plastic flakes into plastic flakes, the waste transparent plastic flakes are stored at 70° C. to 90° C.; Alternatively, it may be carried out in the following order: hot water washing at 85°C to 90°C, ultrasonic washing (temperature from room temperature to 30°C), and nanobubble washing (temperature from room temperature to 30°C). Each wash may last 1 to 2 hours. Next, after dehydration, foreign substances such as heavy metals are separated through a screen operation, and only transparent plastic flakes can be selected. Using an optical sorter, colored waste transparent plastics that are difficult to distinguish with the naked eye are separated from plastic waste and waste transparent plastics are sorted, which can provide recycled raw materials of higher purity.

According to one embodiment, the step of dehumidifying and drying the transparent plastic flake may be performed using a dehumidifier or the like so that the residual moisture is less than 0.2% by weight.

According to one embodiment, in the step of first grinding the transparent plastic flakes, the dehumidified and dried transparent plastic flakes may be put into a grinder and first grinded to a certain size to obtain pulverized material. The particle size of the pulverized product is 0.5 mm to 1 mm; It may be 0.5 mm to 0.8 mm. 10 to 100 in the first grinding process; 18 to 70; Alternatively, fine powder can be obtained by filtering with a 20 to 40 mesh filter.

According to one embodiment, the primary grinded material may be put into an electrostatic separator to classify it according to the type of plastic and remove contaminants to increase purity. For example, at least 95% pure, at least 98% pure, or at least 99% pure, and at least 90% pure; More than 95%; Transparent plastic powder (e.g. PET powder) can be recovered with a recovery rate of over 98%. The electrostatic separator may use any device or system known in the technical field of the present invention as long as it is applicable to transparent plastic classification, and is not specifically mentioned in this specification.

According to one embodiment, the secondary grinding step may be performed by micro grinding to obtain pulverized material cut to a fine size. The particle size of the pulverized material is 0.01 mm to 1 mm; 0.1 mm. to 0.8 mm; 0.1 mm to 0.2 mm; and filtered through a 100 to 400 or 250 to 400 mesh filter. can do.

According to one embodiment, the crystallizing step includes grinding the secondary grinded product at 140°C to 165°C; Alternatively, it may be crystallized at 150°C to 155°C and for about 1 to 2 hours.

According to one embodiment, the pelletizing step involves melting and extruding the crystallized pulverized material using an extruder to pelletize it, and it can be melted by heating at a low temperature of about 250°C to 270°C. In other words, pellets of recycled plastic (i.e., recycled raw material) with a size of 1 mm to 20 mm can be obtained.

According to one embodiment, the pellets of recycled plastic are at least 97%; Alternatively, it may have a purity of 98% or more.

According to one embodiment, the step of adding an additive to the recycled raw material and extruding it involves adding an additive to the obtained plastic pellets, kneading them, and melting and extruding them, and the additive may include a glass bead. The glass beads are contained in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the recycled raw material; 0.5 to 3 parts by weight; Alternatively, it may be included in 1 to 2 parts by weight. By applying the mentioned range, a recycled material with excellent transparency and strength can be provided by preventing a decrease in viscosity while maintaining transparency.

According to one embodiment, the glass beads may be fine particles, porous particles, or hollow particles. For example, it may include a hollow glass sphere, a glass sphere, or both. The hollow glass sphere is 90% or less of the total diameter; 80% to 70%; Alternatively, it may include a hollow size of 60% to 50%. The glass beads may include micro particles, nanoparticles, or both, for example, 300 micrometers (㎛) to 1 nanometer, 50 micrometers to 10 nanometers, 40 micrometers to 100 nanometers; or 40 microns to 1 micron. The glass bead may include borosilicate glass, soda lime glass, or silica (SiO ₂ ).

According to one embodiment, the glass bead may be a glass bead whose surface is coated with a polysiloxane-based resin or an ionic liquid. The glass beads surface coated with the polysiloxane-based resin are 0.1 to 3 parts by weight based on 100 parts by weight of the recycled raw material; 0.5 to 3 parts by weight; Alternatively, it may be included in 1 to 2 parts by weight. In other words, this coating can ensure good dispersion of glass beads within recycled raw materials, prevent a decrease in viscosity, and provide a material with excellent transparency. According to one embodiment, the coating of the mentioned polysiloxane-based resin or ionic liquid is not specifically limited to using a particle coating process known in the technical field of the present invention, and is not specifically mentioned in the present specification.

According to one embodiment, the polysiloxane-based resin has a molecular weight (Mn, Da or g/mol) of 1,000 to 50,000, 10,000 to 50,000; or 20,000 to 40,000, polydispersity (Mw/Mn) (gel permeation chromatography (GPC) method) of 1.6 to 2.5, density of 0.95 g/ml to 1.07 g/ml at 25°C, and viscosity of 25°C. It may be a liquid phase of 100 mPas (cSt) to 3,000 mPas (cSt). The polysiloxane-based resin may be a (meth)acrylated polysiloxane-based compound or a (meth)acrylated organic-modified polysiloxane-based compound. By applying the polysiloxane compound (i.e., liquid phase), an anti-blocking function can be provided while maintaining transparency. Preferably, the polysiloxane-based resin may be one type or a mixture of two or more types selected from the following compounds. In Formulas 1 to 3, n and m are each integers of 1 or more, which may be determined depending on the molecular weight and may be an integer of 1 to 10,000.

[Equation 1]

((0.8-1.2% VINYLMETHYLSILOXANE) - DIMETHYLSILOXANE COPOLYMER, TRIMETHYLSILOXY TERMINATED, 23,000 g/mol, 700-800 cSt, CAS No: 67762-94-1, VDT-127)

[Equation 2]

(VINYL TERMINATED POLYDIMETHYLSILOXANE, 500 cSt, 17200 (g/mol), CAS No: 68083-19-2, DMS-V25R)

[Equation 3]

(VINYL TERMINATED (18-22% DIETHYLSILOXANE) - DIMETHYLSILOXANE COPOLYMER, 150-300 cSt, 8,000-12,000 (g/mol), VDT-123).

According to one embodiment, the ionic liquid and ionic solid include dodecylpyridinium hexafluorophosphate (KOEI), lithium bistrifluoromethanesulfonimide (3M), and tri-n-butylmethylammonium bis-( It may contain one or two or more types selected from the group consisting of trifluoromethanesulfonyl)imide (3M).

According to one embodiment, the polysiloxane-based resin and the ionic liquid are each included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the glass beads; 0.1 to 5 parts by weight; Alternatively, it may be coated at 1 to 3 parts by weight. Throughout the mentioned coating content, the glass beads can be well dispersed, prevent a decrease in viscosity, and provide a material with excellent transparency and strength.

According to one embodiment, the additive further includes a polysiloxane-based resin, an ionic liquid, or both, and the polysiloxane-based resin and the ionic liquid are each contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the recycled raw material. It may be included as a part.

According to one embodiment, the additive may further include silica nanoparticles, and the silica nanoparticles may be spherical silica particles and/or hollow silica nanoparticles. The silica nanoparticles may have a size of 100 nm or less. The silica nanoparticles may be included in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the recycled raw material. By applying the mentioned content, a reduction in viscosity can be achieved and a material with excellent transparency can be provided.

According to one embodiment, the step of cooling the extrudate is a process of cooling the extrudate to room temperature (eg, 20° C. to 30° C.).

According to one embodiment, the drying step includes drying at 160°C to 180°C and a drying time of 3 to 5 hours, so that the moisture content of the extrudate is 0.2% or less; 0.18% or less; 0.17% or less; 0.1% to 0.17%; Alternatively, it can be maintained at 0.14% to 0.17%. By controlling the moisture content through the mentioned drying process, haze can be improved while eliminating blooming and maintaining the optimal IV value. The moisture content can be determined using a device used to measure moisture in solids, films, etc. known in the technical field of the present invention. For example, a moisture meter using multiple NIR wavelengths (e.g. model IR3000) or a heated moisture meter (e.g. model MS_MX-MF_ML) can be used, and the moisture measurement method is not specifically mentioned.

According to one embodiment, the extrudate may be a variety of extruded products such as recycled transparent plastic sheets, films, beads, fibers, etc. Preferably, it may be a transparent PP recycled sheet. According to one embodiment, the extrudate can provide a recycled sheet or film of transparent polyethyleneterephthalate (PET) or polypropylene (PP) suitable for use in various packaging and display purposes. According to one embodiment, the extrudate may be a transparent plastic container such as a PET bottle. According to one embodiment, the extrudate has a haze of 5% or less; 3% or less; or 1% or less, and the light transmittance is 85% or more; More than 88%; over 90; Alternatively, it may be 95% or more and IV (intrinsic viscosity, dL/g) may be 0.7 to 1.

Hereinafter, the present invention will be described in detail through examples and experimental examples to specifically explain the present invention. However, the embodiments according to the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described in detail below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example 1

Transparent PP recycled pellets (purity 99%) of approximately 1 mm in size obtained through the mentioned recycling process were prepared. The transparent PP recycled pellets were obtained by drying the transparent PP recycled extrudate cooled in the recycling process at 170° C. for 4 hours to have a moisture content of about 0.167% to 0.168%.

Knead transparent PP recycled pellets and 1% by weight Hollow Glass Sphere (HL50, Hollowlite, Bulk Density 0.25-0.27g/cm³, D50 ≤ 40μm, True Density 0.48-0.52g/cm³) and knead under the conditions of 210 ℃ to 250 ℃ and maximum pressure. It was melt-extruded through an extrusion die at 110 bar to produce a transparent sheet (thickness 100 ㎛). Next, it was aged at 40°C to 50°C for 24 hours and cooled to room temperature.

Example 2

The procedure was the same as in Example 1 except that Hollow Glass Sphere (HL50) coated with 2% by weight of the polysiloxane-based compound below was added. The moisture content is approximately 0.166%.

[Equation 2]

(VINYL TERMINATED POLYDIMETHYLSILOXANE, 500 cSt, 17200 (g/mol), CAS No: 68083-19-2, DMS-V25R)

Example 3

The procedure was the same as in Example 1 except that Hollow Glass Sphere (HL50) coated with 2% by weight of dodecylpyridinium hexafluorophosphate (KOEI) was added. The moisture content is approximately 0.169%.

Example 4

The procedure was the same as in Example 1 except that glass beads (S-SLGMS-2.5, Cospheric, average size: 35 μm to 37 μm, Soda Lime Solid Glass Microspheres) were applied. The moisture content is approximately 0.165%.

Example 5

The procedure was the same as in Example 1 except that 0.1% by weight of glass beads (average particle size: 9 μm to 13 μm, BET surface area: 125 m2/g, product number: 440345, Aldrich) was added. The moisture content is approximately 0.167%.

Example 6

Transparent PET recycled pellets (purity 99%) of approximately 1 mm in size obtained through the mentioned recycling process were prepared. The transparent PP recycled pellets were obtained by drying the transparent PET recycled extrudate cooled in the recycling process at 170° C. for 4 hours to have a moisture content of about 0.165%.

The procedure was the same as Example 1 except that transparent PP recycled pellets and Hollow Glass Sphere (HS60, D50 (μm) ≤ 16), which were recycled raw materials, were used.

Comparative Example 1

The procedure was the same as in Example 1 except that transparent PP recycled pellets were extruded without additives.

Comparative Example 2

The procedure was the same as in Example 4 except that 8% by weight of glass beads was added.

Physical property evaluation

The moisture content was measured using a near-infrared (IR)-based moisture meter (model IR3000).

The physical properties below were evaluated and shown in Table 1.

Haze value

A test piece bonded to alkali-free glass (total light transmittance 92%, haze 0.4%) with a thickness of 800 μm was used, and the haze was measured using a haze meter (“HM-150” manufactured by Murakami Shikisai Kijutsu Kenkyu Co., Ltd.). . The value obtained by subtracting the haze (0.4%) of the alkali-free glass from the measured value was taken as the haze of the adhesive sheet. The total light transmittance and haze values for light with a wavelength of 550 nm were measured using a hazemeter and are shown in Table 1 below.　

light transmittance

Light transmittance at a wavelength of 550 nm was measured using a UV spectrophotometer (UV-3600, Shimadzu).

Intrinsic viscosity (dL/g)

Intrinsic viscosity was evaluated using the conventional ASTM D 4603 method. In detail, solid samples were dissolved in solvent at different concentrations, the viscosity was measured using an Ubbelohde viscometer (Capillary Viscometer) at a constant temperature, and then a viscosity vs. concentration graph was obtained. The intrinsic viscosity was calculated by extrapolation using .

Tensile Strength (kgf/㎟)

A measurement specimen was made in accordance with ASTM D 638 and the tensile strength was measured using a universal testing machine.

Specimen 1: Release paper (width: 25mm, length: 300mm, thickness: 164㎛) - 5ea

Specimen 2: Release film (width: 25mm, length: 300mm, thickness: 25㎛) - 5ea

In the test method, a tensile strength test was performed on specimens 1 and 2 at 90 peel using a tensile strength tester.

The present invention can provide transparent PET and transparent PP recycled sheets with high transmittance and strength by improving haze value and viscosity (i.e., stable IV value). The present invention can provide a constant IV value even after repeated regeneration, reduce haze generation, and provide a regenerated product with high transparency.

The above-described embodiments of the present invention have been disclosed for illustrative purposes, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions will be possible. should be regarded as falling within the scope of the patent claims below.

Claims (5)

Preparing transparent plastic recycled raw materials;
Adding additives to the recycled raw material and extruding it;
cooling the extrudate; and
drying the cooled extrudate at a drying temperature of 160° C. and a drying time of 3 hours;
Including,
The drying step maintains the moisture content of the extrudate below 0.2%,
The recycled raw material is polypropylene recycled pellets,
The additive includes glass beads,
The glass beads are included in an amount of 0.2 to 3 parts by weight based on 100 parts by weight of the recycled raw material,
The additive further includes polysiloxane resin, ionic liquid, or both,
The polysiloxane-based resin has a molecular weight (g/mol) of 1,000 to 50,000, a viscosity of 100 cSt to 3,000 cSt, and a density of 0.95 g/ml to 1.07 g/ml,
The polysiloxane-based resin and the ionic liquid each contain 0.1 to 2 parts by weight based on 100 parts by weight of the recycled raw material,
The ionic liquid includes dodecylpyridinium hexafluorophosphate (KOEI), lithium bistrifluoromethanesulfonimide (3M), and tri-n-butylmethylammonium bis-(trifluoromethanesulfonyl)imide ( 3M), comprising one or two or more selected from the group consisting of recycled polypropylene film manufacturing method.
According to paragraph 1,
The glass beads include borosilicate glass, soda lime glass, or both,
The glass beads include hollow glass spheres, glass spheres, or both,
A method for producing a recycled polypropylene film, wherein the size of the glass beads is 50 ㎛ (micrometer) to 10 nanometers.
According to paragraph 2,
The glass beads include glass beads surface-coated with polysiloxane resin or ionic liquid;
It further includes,
The polysiloxane-based resin is coated in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the glass beads,
A method for producing a recycled polypropylene film, wherein the glass beads surface coated with the polysiloxane resin are included in an amount of 0.1 parts by weight to 3 parts by weight based on 100 parts by weight of the recycled raw material.
delete It is an extrudate manufactured by adding additives to transparent plastic recycled raw materials and extruding them.
The recycled raw material is polypropylene recycled pellets,
The additive includes glass beads,
The glass beads are included in an amount of 0.2 to 3 parts by weight based on 100 parts by weight of the recycled raw material,
The additive further includes polysiloxane resin, ionic liquid, or both,
The polysiloxane-based resin has a molecular weight (g/mol) of 1,000 to 50,000, a viscosity of 100 cSt to 3,000 cSt, and a density of 0.95 g/ml to 1.07 g/ml,
The polysiloxane-based resin and the ionic liquid each contain 0.1 to 2 parts by weight based on 100 parts by weight of the recycled raw material,
The ionic liquid includes dodecylpyridinium hexafluorophosphate (KOEI), lithium bistrifluoromethanesulfonimide (3M), and tri-n-butylmethylammonium bis-(trifluoromethanesulfonyl)imide ( Contains one or two or more types selected from the group consisting of 3M),
The extruded product has a haze of 5% or less, a light transmittance of 85% or more, and an IV (intrinsic viscosity, dL/g) of 0.7 to 1.5.