JPS587329A - Manufacture of polyolefin film - Google Patents

Abstract

PURPOSE:To obtain the titled film efficiently that is excellent in transparency, rigidity, easy heat sealability and useful for common packaging etc. by melting and extruding specific crystalline propylene-alpha-olefin copolymer and high density polyethylene under a specific condition. CONSTITUTION:Where polypropylene is crystalline propylene-alpha-olefin copolymer containing 70% or more of propylene component when the crystalline melting point is 150 deg.C or lower, polyethylene is high density polyethylene having a density 0.945 or more and a flow ratio 15 or less and the ratio of the melt index (MI) of polyethylene to the melt flow rate (MFR) of polypropylene is (MI/MFR)>=1.2, the composition composed of 96-85% by weight of polypropylene and 4-15% by weight of polyethylene is melted and extruded at 180-250 deg.C and then cooled quickly to 50 deg.C or lower to obtain the desired film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for making IIA of polyolefin films. More specifically, the present invention relates to a method for preparing a low-electricity heat-sealable polyolefin fill having excellent properties and rigidity.

In recent years, ethylene-propylene random copolymer, ethylene-propylene-1ten-1 copolymer IK Kurata, propylene-
Crystalline propylene-1-olefin copolymer bodies mainly composed of propylene, such as butene-1 copolymer, have a zeta layer and general packaging that take advantage of their excellent transparency, impact resistance, and low-temperature heat-sea properties. In addition to other uses, it can also be used for a wide range of people! JIl has been done.

As the amount of smonomer iit in the crystalline propylene-α-olefin copolymer increases, the koji crystal melting point of the copolymer decreases and
Although the sex increases due to high speed heat sea, MIIK FiAA
stiffness decreases. For example, in the case of an unstretched film, compared to a crystalline bopple pyrene film whose crystal melting point is 164°C, the koji crystalline ethylene-propylene-Zunda A coheavy metal body has a crystalline melting point of 150 to 140 Cf). 2o~4o*
4b decreases. Therefore, by improving sealing performance, l
Increasing the content of the comonomer in the copolymer for the purpose of making plastic bags and automatic packaging can lead to wrinkles during film formation due to a decrease in film properties, thickening of both ends due to tightening during winding, etc. This not only causes poor flatness of the film, but also causes problems such as smudges and elongation of the film, which reduces workability in printing, bag making, automatic wrapping, etc. This stiffness is due to the film's thin edge processing characteristics, and the decrease in stiffness is a major hindrance to thinning the film for the purpose of resource saving.

As a result of various studies aimed at improving the rigidity of the crystalline globylene-α-olefin copolymer without impairing its excellent transparency and low-temperature heat sealability, the present inventors found that
We learned that the above object can be achieved by forming a film under specific conditions from a composition in which a crystalline propyleae α-olefin copolymer is mixed with a specific high-density polyethylene in a specific ratio, which led us to complete the present invention. Ta.

That is, in the present invention, polypropylene has a crystal melting point of 150
℃ or less, Toj+ is a crystalline propylene-a-olefin/copolymer having a propylene component of 70 or more, and polyethylene has a density α? 45 or more, and the carbon dioxide is 15 or less, and the ratio of the media index (MI) of the polyethylene to the media rate (MFR) of the poly-10 pyrene is (MI/ MPi)≧
A propellant consisting of 96 to 85 weight of polypropylene such as 12 and 4 to 15 weight of polyethylene was added to 180
These are the transparent l# method, which is characterized by IFlk extrusion at ~250C and rapid cooling to 50C or less, and the m-adic method of high-stiffness heat-sealable polyolep infill.

The polypropylene used in the present invention has a propylene component of 7
The globylene-α-olefin copolymer must contain 0 weight or more, and must have a crystal melting point of 150 or less. If the propylene component is not suitable for 70 weight tsK, the obtained film is likely to cause blocking, and if the crystal melting point exceeds 15 DC, low temperature heat sealability and high speed heat sealability will be significantly reduced, both of which are unfavorable.

Such polypropylene can be produced by randomly copolymerizing the main component propylene and the comonomer ethylene or an α-olefin having 4 to 8 carbon atoms by a known method using, for example, a Ziegler Φ jujube catalyst. . Examples of such copolymers include ethylene-propylene copolymers,
Examples thereof include No. 1 copolymer, ethylene-propylene-butene-1 terpolymer, and the like.

In the present invention, the crystal melting point (hereinafter abbreviated as Tm) means:
A sample was heated for 10 minutes in a nitrogen atmosphere using a running-type differential thermometry meter.
The crystals obtained by increasing the temperature at a rate of ℃/min are 9
Refers to the peak temperature of the endothermic curve. Tm is 105-112°C for low-density polyethylene, 124-162°C for high-density polyethylene, and 162-162°C for crystalline polypropylene.
The temperature is 165°C. In addition, in crystalline propylene-α-olefin/copolymer, when the content of the comonomer component increases, T
m decreases, and in the case of a gotylene-propylene Sundam copolymer, when the ethylene component in the copolymer exceeds 25% by weight, Ta decreases to 150° C. or lower. In addition, ethylene-propy V
When block copolymerization is performed, such as Tm#'i, -Tsu [1 at 150 C or higher], the resulting film has better rigidity but significantly lower transparency, so this book I
Cannot be used under AwA.

The polyethylene used in the present invention has a density of 1945 or more,
High-density polyethylene with a 7o-ratio of 15 or less.

If the density of polyethylene is less than a945, the effect of improving rigidity is insufficient. - If the ratio exceeds 15, the transparency of the film decreases, which is not preferable.

In order to effectively apply this method, high-density polyethylene having a density of 0.955 or more and a teflow ratio of 8 to 12% is preferably used.

Zero shot f! In A#c, the density refers to the density measured based on JIS K6760 (polyethylene test method).

In addition, the flow ratio (hereinafter abbreviated as F) is JI8
In the K67600 melt index (hereinafter abbreviated as MI) measurement method, the value obtained using a load (Mllo) of 1a81g#) is the value obtained using a normal 2.16 wheel load (MI). The quotient obtained by dividing the In other words, it is 1"1a". FR large surface polyethylene has a wide molecular weight distribution and tends to have excellent fluidity, but when PR exceeds 15, the transparency of the resulting film decreases. It cannot be used in the method of the present invention because of this.

The polypropylene and polyethylene used in this invention have a ratio of MI of polyethylene to melt flow rate of polypropylene (hereinafter referred to as string 1) of 12 or more, that is,
MI/MIFR≧12 and 69, and the crystallization ratio is polypropylene 96 to 85 weight-, polyethylene 4 to 15
The ratio of MI and MFfL must be in the range of s.
Reached 2L! If the mixing ratio of polyethylene is less than 4s, the effect of improving the rigidity is insufficient, and if it exceeds 15s, the film becomes brittle and the properties are greatly reduced, both of which are undesirable. In addition,
In this J1@, group 1 is JIJli K675B
(Polybupylene test method).

The composition comprising the above polypropylene and polyethylene used in this JA@ contains stabilizers, processing aids, antistatic agents, etc. commonly used for polyolefins, as necessary.
In addition to flame release agents and fillers, false polymers such as ethylene-propylene rubber and ethylene-vinyl acetate copolymers may be added within limits that do not impair the purpose of the present invention.

As a method for growing a film using the above composition,
Any of the known T-die and tube methods can be used, but the film must be formed under conditions such that the composition is S-melt extruded at 180 to 250C in an extruder and die and is rapidly cooled to 50C or less. No. When the temperature of melt extrusion reaches 180C, the transparency of the surface and film deteriorates, and when it exceeds 250C, there is a risk of fish eyes due to gelation of polyethylene.
In addition, the film engraving properties are unstable due to the difference in f and dynamics between both resins.9 Both are unfavorable, and the cooling temperature after melt extrusion is 50°C or lower, preferably 40°C or lower.
If the temperature exceeds 0.degree. C., the film becomes cloudy due to crystallization of the polyethylene, the transparency becomes less comfortable to wear, and the film becomes brittle, which is not preferable.

The film obtained by the method of the present invention has transparency, low-temperature heat-sealability, and high-speed heat-sealability! It has excellent rigidity and R#c compared to the conventionally known film AK, so it not only has a wide range of uses mainly for wrapping purposes as a single film or a laminated film, but also for the same conventional use. The thickness is about 20 to 50 mm compared to the film for
This is extremely useful from the perspective of resource conservation as it gets very hot.

The present invention will be explained in detail below using examples. 2&O, the method for measuring and determining the film 4I property used in the experiment fl is shown below.

(1) alllk: Turbidity according to A8TMD1001 K, - (dynamic stiffness: Young's modulus (1 thymogietes) according to A8TMD882 K, kg/m μ) Heat sea J/a, sealing temperature at which a seal strength of 500f/15■ is obtained, C Sealing conditions: Toyo Seiki thermo-inclined seam with temperature measuring device, sealing pressure 1V-G, 1 second tensile test; sample width 15M, tensile speed 60011I
/sII The flatness of the surface of the obtained roll, the winding wrinkles, the thickening of the roll end, etc. were observed.

(6) Fish eye with a diameter of 0.1 - or more using Fish Eye Electric Manufacturing Co., Ltd.' Fish Eye Counter TPLSil' for 1000 m? The number of hits was measured.

Examples 1-8. Comparative Examples 1 to 10 Various globylene-α-olefin copolymers (phenolic antioxidant α1, calcium stearate [1,
1. Erucic acid amide (containing 11%) and polyethylene (phenol-S antioxidant CTIS, calcium stearate) were added to the thickness by T-die method under the conditions of melt extrusion temperature 220C and cooling roll temperature 50C. A film having a size of 30# and a width of 500 mm was formed, and 1000 rolls of each film were wound onto a paper tube.The characteristics of the obtained film and the form of the film are also listed in Table 1.

The following is clear from the results in Table 1.

(1) 211pyrene-α-olefin co-141 body f
) When Twa becomes low, the heat sealability improves, but the rigidity decreases significantly and the film winding flame becomes poor.

(a) Film manufactured under conditions limited in the present invention (
Examples 1 to 8) have excellent properties in terms of transparency, rigidity, impact strength, heat sealability, and film shape; however, the films outside the scope of the present invention (Comparative Example 1)
Items 1 to 10) have a defect in at least one of the above properties and are not preferred in practice.

Examples 9-16. Ratio @1111~15 Ethylene content 2.811.1 Ten-1 content 53-#Tm
144°C, MFR7, ethylene-propylene-butene-1 terpolymer and phenolic antioxidant (119
6, calcium stearate a1-.

Containing erucic acid amide a1-, silica Q, 1-)9
S-% Density Q, 96Q, MI 111
0, li'Rs! 0 high-density polyethylene (phenolic antioxidant α1S, calcium stearate 0
．． Using a composition containing 711 (containing 1LIII) and changing various film forming conditions (melt extrusion temperature and cooling roll temperature), the T-die method was used to form a film with a thickness of 25 μm, @! 400 pieces of film were obtained. Table 2 shows the film forming conditions and the properties of the obtained film.

From the results in Table jI2, it is clear that the method of the present invention provides a film with excellent properties.

112 tables There is surging in book 1 Book 2 surging large that's all

Claims (1)

[Claims] Polypropylene is a crystalline boopylene-α-olefin copolymer with a crystal melting point of 150 C or less and a propylene component of 70 or more.
45 or more and 7 dimensional polyethylene of 15 or less), and the polyethylene's Meme Toindex (
(MI) and the polypropylene (MI)
MFR) ratio is (MI741FR)≧t2! 6-85 weight- and polyethylene 4-1
5 weight - SS at 180-250℃
1. A method for producing a heat-sealable polyolea film having excellent transparency and rigidity, which involves extrusion and heating at 50° C. or lower.