JPH0259767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated film based on poly-4-methyl-1-pentene having excellent heat sealability. Poly-4-methyl-1-pentene is characterized by its transparency,
Taking advantage of its heat resistance and chemical resistance, it is used for chemical experiment equipment such as beakers and graduated cylinders, syringes for syringes, optical measurement cells, microwave oven trays, and baking cartons by coating paper. However, while poly-4-methyl-1-pentene has a high melting point and good heat resistance,
It has the disadvantage of poor heat sealability.
As a method for improving heat sealability, polyethylene, polypropylene, etc., poly(4-methyl-1-
The most common method is to bond poly-4-methyl-1-pentene with a resin that has a lower melting point than pentene and has excellent heat-sealability.
-Although pentene is a polyolefin, it has poor adhesive properties and cannot be put to practical use simply by laminating layers.Additionally, poly(4-methyl-1-pentene) film is coated with a urethane adhesive or the like as an anchor coating agent. Even when a polyethylene film or the like is laminated, the poly-4-methyl-1-pentene film has poor surface wettability, the adhesive strength of the laminated film is low, and the heat sealability is not improved to the extent shown above. In view of this situation, the present inventor conducted various studies to improve the heat-sealability of poly-4-methyl-1-pentene film, and as a result, developed poly-4-methyl-1-pentene film.
By using a specific propylene/α-olefin random copolymer as an adhesive layer when laminating pentene film and polyethylene film or polypropylene film, adhesive strength is improved and a laminated film with excellent heat sealability can be obtained. This led to the completion of the present invention. That is, in the present invention, at least one side of the poly-4-methyl-1-pentene (A) layer has a propylene content.
50 to 87 mol% and differential scanning calorimetry (DSC)
The heat of crystal fusion is 10 or more based on thermal analysis of
A heat-sealing product characterized by laminating a polyethylene (C) or polypropylene (D) layer or a mixture layer thereof through a propylene/α-olefin random copolymer (B) layer of 80 Joule/g. This provides an excellent laminated film. Poly4-methyl-1-pentene used in the present invention
(A) is a homopolymer of 4-methyl-1-pentene or 4-methyl-1-pentene and other α-olefins, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1- Desen,
A copolymer with an α-olefin having 2 to 20 carbon atoms such as 1-tetradecene and 1-octadecene, which usually contains 85 mol% or more of 4-methyl-1-pentene.
-It is a polymer mainly composed of methyl-1-pentene. Melt flow rate of poly4-methyl-1-pentene (A) (MFR ₅ load: 5Kg, temperature: 260℃)
The MFR 5 is preferably in the range of 0.5 to 200g/10min, but if it is less than 0.5g/10min, the melt viscosity is high and the moldability is poor, and if the MFR ₅ is over 200g/10min, the melt viscosity is low and the moldability is poor. , and its mechanical strength is also low. The propylene/α-olefin copolymer (B) used in the present invention has a propylene content of 50 to 87 mol%, preferably 60 to 80 mol%, and crystals based on thermal analysis using a differential scanning calorimeter (DSC). Heat of fusion is 10 to 80 Joule/g, preferably 20 to 80 Joule/g
70Joule/g, preferably MFR ₂
(MFR ₂ : ASTM D 1238, L) is 0.5 to 200
g/10min, more preferably 2 to 50g/
10 min, preferably with a melting point in the range of 90 to 130°C, preferably 110 to 125°C. If the propylene content exceeds 87 mol% or the heat of crystal fusion exceeds 80 Joule/g, the adhesion to poly4-methyl-1-pentene (A) is poor, and polyethylene (C) or polypropylene (described later) Even if it is laminated with (D), the heat sealability is not improved. On the other hand, those with a propylene content of 50 mol% or a crystal fusion heat of less than 10 Joule/g have adhesive properties, but have weak adhesive strength and poor heat resistance, so they have little effect on improving heat sealability, and This is not preferable since it may impair the heat resistance, which is an inherent characteristic of 4-methyl-1-pentene. Furthermore, those with MFR ₂ outside the above range may have poor moldability, and those with melting points outside the above range also tend to have poor adhesiveness. In addition to the above properties, the propylene/α-olefin random copolymer (B) used in the present invention also has the following properties:
The microisotacticity (hereinafter abbreviated as MIT) of three propylene chains is 0.7 or more, and
0.8 or more and boiling n-heptane insoluble content is 5% by weight
Preferably, the content is preferably 3% by weight or less.
If a film with an MIT of less than 0.7 is used, low molecular weight substances may bleed out at the film interface after aging, reducing adhesive strength.
The large amount of boiling n-heptane insoluble matter is due to the large amount of propylene block polymerized components, and when such a copolymer is used, the effect of improving adhesion may be small. In the random copolymer (B), the α-olefin copolymerized with propylene is usually an α-olefin having 2 to 20 carbon atoms excluding propylene, and specifically, for example, ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene,
1-octene, 1-decene, 1-tetradecene,
Examples include 1-octadecene. Among these, those having 4 to 10 carbon atoms are particularly preferred. The heat of fusion of the random copolymer (B) in the present invention is measured by measuring the specific heat curve of the copolymer in a completely molten state (preferably the specific heat curve shown at 160°C or higher and 240°C or lower) using a differential scanning calorimeter. This is a value calculated using a straight line obtained by direct extrapolation to the low temperature side as the baseline. The heat of fusion and melting point are measured under the following measurement conditions. That is, after leaving the sample at 200℃ for 5 minutes,
Cool down to -40℃ at a rate of ℃/min, and cool down to -40℃ for 5 minutes.
Leave for a minute. After that, at a heating rate of 20℃/min -
Measurements are taken from 40℃ to 200℃. Microisotacticity is a value determined by focusing on three propylene chains using ¹³ C nuclear magnetic resonance spectroscopy, and quantifying the fraction in which three propylene chains are arranged isotactically. The amount of boiling n-heptane insoluble matter is determined by the following method. That is, a small sample of approximately 1 mm x 1 mm x 1 mm and glass beads are placed in a cylindrical glass filter (G3) and extracted using a Soxhlet extractor.
Extract for 14 hours. In this case, the reflux frequency is approximately once/5 minutes. The weight percent of insoluble matter is determined by weighing the molten part or insoluble matter. Propylene content with the above properties
The 50 to 87 mol% propylene/α-olefin random copolymer (B) is, for example, (a) a composite containing at least magnesium, titanium, and halogen, (b) a metal from Group 1 to Group 3 of the periodic table. It is obtained by random copolymerization of propylene and α-olefin using a catalyst formed from an organometallic compound and (c) an electron donor. Part or all of the electron donor (c) may be immobilized on part or all of the complex (a), or may be brought into preliminary contact with the organometallic compound (b) prior to use. Good too. Particularly preferred is an embodiment in which a part of the electron donor (c) is immobilized on the complex (a), and the remainder is added to the polymerization system as it is or is used after being brought into preliminary contact with the organometallic compound (b). be. In this case, the electron donor immobilized on the complex (a) and the electron donor used by directly adding it to the polymerization system or by pre-contacting it with (b) may be the same or different. It's okay. The polyethylene (C) used in the present invention refers to a homopolymer of ethylene or ethylene and other α-olefins, specifically, for example, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene,
1-octene, 1-decene, 1-tetradecene,
It is a copolymer with 1-octadecene, etc., or a vinyl compound such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, etc., and usually has an ethylene content of 92 mol% or more, preferably 95 mol% or more. It is a crystalline polymer as the main component. Specific examples of these polyethylenes (C) include high-pressure low-density polyethylene (so-called LDPE), ethylene-propylene copolymer, ethylene-1-butene copolymer, and ethylene-4-methyl-1-pentene copolymer. , and ethylene-1-hexene copolymer (so-called LLDPE), high-density polyethylene (so-called
HDPE), ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer, etc. Further, the polyethylene (C) used in the present invention may be graft-modified with an unsaturated carboxylic acid such as maleic anhydride or maleic acid. Among these,
LDPE, ethylene/α-olefin copolymer, ethylene/vinyl acetate copolymer, etc. are preferable because they have excellent transparency and low-temperature heat-sealability, and especially those with a density of 0.910 to 0.960 and a melting point (Tm: ASTM D
3417) is preferably in the range of 100 to 135°C. The melt flow rate (MFR ₃ : ASTM D 1238, E) of polyethylene (C) is not particularly limited, but is usually 0.01 to 30 from the viewpoint of moldability.
g/10 min, preferably in the range of 0.1 to 10 g/10 min. The polypropylene (D) used in the present invention is a propylene homopolymer or a propylene and 10 mol%
Hereinafter, preferably 5 mol% or less of other α-olefins, specifically, for example, ethylene, 1-butene,
4-methyl-1-pentene, 1-hexene, 1-
It is a crystalline polymer mainly composed of propylene, such as a random or block copolymer with octene, 1-decene, 1-tetradecene, etc. Among these, homopolymers and random copolymers are preferred because they have excellent transparency, and in particular, melting point (Tm:
A random copolymer having an ASTM D 3417) temperature of 130 to 140°C is preferred because it has excellent heat sealability. The MFR ₂ of polypropylene (D) is not particularly limited, but it is usually 0.5 to 30 from the viewpoint of moldability.
g/10 min, more preferably in the range of 0.5 to 10 g/10 min. The laminated film of the present invention includes the polyethylene (C) or polypropylene layer, with the propylene/α-olefin random copolymer (B) layer interposed on at least one side of the poly4-methyl-1-pentene (A) layer. It is a laminated film formed by laminating layers (D) or a mixture thereof. The laminated film of the present invention can be produced by various known methods. For example, after forming a poly4-methyl-1-pentene (A) film in advance, propylene/α-
Olefin random copolymer (B) and polyethylene
(C) or polypropylene (D) or a mixture thereof, a method of extrusion coating a poly4-methyl-1-pentene (A) film in advance and then separately molding a polyethylene (C) film or a polypropylene film, or a mixture thereof. A method of extrusion laminating a film consisting of propylene/α-olefin random copolymer (B), or poly4-methyl-1-pentene (A), propylene/α-olefin random copolymer (B) and Examples include a method in which polyethylene (C), polypropylene (D), or a mixture thereof is coextruded using a multilayer die having at least a three-layer structure, and a propylene/α-olefin random copolymer (B) is used as an intermediate layer. However, the coextrusion molding method is preferred because it is easy to operate and provides a laminated film with better interlayer adhesion. Coextrusion molding methods include a T-die method using a flat die and an inflation method using a circular die. The flat die may be either a single manifold type using black boxes or a multi-manifold type. As for the die used in the inflation method, any known die can be used. The thickness of each layer of the laminated film of the present invention is not particularly limited, but the poly4-methyl-1-pentene (A) layer is usually 10 to 100μ, preferably 10 to 50μ, and the propylene/α-olefin random layer is usually 10 to 100μ. The polymer (B) layer has a thickness of 5 to 50μ, preferably 10 to 30μ, and the heat seal layer of polyethylene (C) usually has a thickness of 10 to 100μ, preferably 10 to 50μ. The laminated film of the present invention is poly4-methyl-1
- There is no particular limitation as long as the pentene (A) layer/propylene/α-olefin random copolymer (B) layer/polyethylene (C) layer or polypropylene (D) layer or a mixture layer thereof is a constituent element, Poly 4
- A heat seal layer such as polyethylene (C) may be laminated on both sides of the methyl-1-pentene (A) layer via a propylene/α-olefin random copolymer (B) layer, and further, polyvinyl alcohol,
Saponified ethylene/vinyl acetate copolymer, polyamide, polyester, paper, aluminum foil, etc. may be laminated. Poly4-methyl-1-pentene (A) layer, propylene/α-olefin random copolymer (B) layer and polyethylene (C) that constitute the laminated film of the present invention
Weather-resistant stabilizers, heat-resistant stabilizers, antistatic agents, antifogging agents, anti-blocking agents, slip agents, lubricants, pigments, dyes, droplet agents, and nucleating agents are added to any or all layers of the heat-sealing layer. Various compounding agents that are normally added to polyolefin such as polyolefins may be added to the extent that they do not impair the purpose of the present invention. For the purpose of further improving heat sealability, low-crystalline or amorphous ethylene/propylene copolymers, ethylene/α-olefin copolymers such as ethylene/1-butene copolymers, ethylene/acetic acid A vinyl copolymer or the like may also be added. The laminated film of the present invention is suitable for packaging various foods (e.g. vegetables, confectionery, meat), breads, and marine products by taking advantage of its transparency, heat resistance, stain resistance, and water repellency. EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way unless it goes beyond the gist thereof. Example 1 4-methyl-1-pentene/1-decene copolymer (hereinafter abbreviated as TPX-) with density: 0.835 g/cm ³ and MFR ₅ : 26 g/10 min, propylene content:
71.0 mol%, heat of crystal fusion: 50 Joule/g, melting point: 110°C, MFR ₂ : 7.0 g/10 min, boiling n-heptane insoluble content: 0.5%, boiling methyl acetate soluble content:
Propylene/1-butene random copolymer (hereinafter abbreviated as PBR-) with 0.5% and MIT: 0.94, density 0.917 g/cm ³ , MFR ₃ : 6.5 g/10 min and
Tm: 105℃ high pressure polyethylene (LDPE-
) and PBR− as the middle layer, respectively 40
After melting in mmφ extruder (cylinder temperature 270℃), 40mmφ extruder (cylinder temperature 250℃) and 40mmφ extruder (cylinder temperature 250℃), from spiral die for three-layer inflation film forming (die temperature 260℃) Extrusion, water cooling, TPX−:
A coextruded three-layer film consisting of 20μ, PBR-: 20μ and LDPE-: 20μ was obtained. Next, the physical properties were evaluated by the following method. Adhesive strength (g/15mm): Cut a 15mm wide test piece and crosshead speed.
It is shown as the strength when peeling between each resin layer at 200 mm/min. Peel strength of heat-sealed part (g/15mm): LDPE film surfaces or PP film surfaces were stacked together and heat-sealed with a seal bar with a width of 10mm at a temperature of 120℃ and 250℃ and a pressure of 2Kg/cm ² for 1 second. Leave to cool afterwards. A test piece with a width of 15 mm was cut from this, and the strength was measured when the heat-sealed portion was peeled off at a crosshead speed of 200 mm/min. The results are shown in Table 1. Example 2 The same procedure as in Example 1 was carried out, except that the three-layer film of Example 1 was replaced by a coextruded three-layer film in which each layer had a thickness of 50 μm. The results are shown in Table 1. Example 3 Instead of the LDPE used in Example 1, density: 0.91 g/cm ³ , MFR: 5 g/10 min and Tm:
Example 1 except that propylene/ethylene random copolymer (hereinafter abbreviated as PP-) at 140°C was used and the cylinder temperature of the PP- extruder was set at 270°C.
I went in the same way. The results are shown in Table 1. Comparative Example 1 In Example 1, without using PBR- in the intermediate layer,
The same procedure as in Example 1 was carried out except that a two-layer film of TPX and LDPE was used. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1 Propylene content 50 to 87 mol% on at least one side of the poly4-methyl-1-pentene (A) layer
and propylene α- with a heat of crystal fusion of 10 to 80 Joule/g based on thermal analysis using a differential scanning calorimeter.
1. A laminated film comprising a polyethylene (C) or polypropylene (D) layer or a mixture layer thereof laminated via an olefin random copolymer (B) layer.