JPH0491148A - Self-adhesive film for packaging - Google Patents

Abstract

PURPOSE:To obtain the subject film suitable for wrapping film, etc. in home or business having self-adhesiveness, transparency or cutting properties, etc., by mixing a specific ethylene.alpha-olefin copolymer with at least a species selected from ethylene.alpha-olefin copolymer, etc., having a specific density. CONSTITUTION:(A) 80-20 pts.wt. ethylene.alpha-olefin copolymer derived from copolymerization of ethylene having density lower than 0.860-0.910g/cm<3>, >=100 deg.C maximum peak temperature measured by a differential scanning calorimeter and >=10 pts.wt. boiling n-hexane insoluble component with 3-12C alpha-olefin is mixed with at least a species selected from (B) 20-80 pts.wt. ethylene.alpha-olefin copolymer having 0.91-0.97g/cm<3>, (C) 10-80 pts.wt. high-pressure polyethylene (copolymer) and (D) 10-30 pts.wt. propylene (co)polymer.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an ethylene/α-olefin copolymer film that has good self-adhesiveness and transparency, and excellent cuttability and microwave oven properties. Related to household and commercial lamp films and masking films.

[Conventional technology] Conventionally, wrap films are made of polyvinylidene chloride resin (PV
Films mainly composed of high-pressure polyethylene (abbreviated as HPLDPE), or films containing linear low-density polyethylene (abbreviated as LLDPE) and HPLDPE have been proposed and put into practical use. In addition to self-adhesiveness, this wrap film is required to have cuttability, strength during packaging, transparency, microwave oven properties (heat resistance), safety, and not polluting the environment.

However, since PVDC and polyvinyl chloride resins contain a large amount of chlorine, they generate chlorine gas when incinerated, and the plasticizers contained in large amounts are harmful. Furthermore, since the PVDC wrap film is biaxially stretched, it tends to tear diagonally when cut and has the disadvantage of shrinking significantly when heated in a microwave oven. For this reason, HPLDPE, which does not have these problems, is used alone, but it does not have sufficient heat resistance and has very low self-adhesiveness, so it is necessary to add various tackifiers. 58-12141). If there is too much tackifier, the tackifier will bleed onto the surface of the film and cause stickiness, while if it is too little, it will not be possible to obtain adequate tackiness. A packaging film prepared by adding liquid polybutene as a tackifier to a composition consisting of HPLDPE and LLDPE (Japanese Patent Laid-Open No. 57-1823)
No. 41) is also disclosed, but the problem of bleed-out of the tackifier is unavoidable.

On the other hand, wrap films made of LLDPE alone have problems such as insufficient self-adhesiveness and the tendency to tear diagonally.
Wrap films made of PLDPE alone have the above-mentioned problems, so there is a method to cover the drawbacks of both by blending HPLDPE with LLDPE (Japanese Patent Publication No. 54-25952, Japanese Patent Publication No. 1-48132), or Furthermore, a wrap film containing silicone oil and anti-fog agent (
JP-A-2-133433) has been proposed.

However, the films obtained by these methods do not necessarily have self-adhesive properties, and have the disadvantage that when the amount of HPLDPE is increased, the adhesion decreases, and when the amount of HPLDPE is decreased, the cuttability deteriorates. There is still room for improvement as a self-adhesive film for packaging, as adding an antifogging agent can cause problems such as bleed-out and increased costs.

[Problems to be Solved by the Invention] The present invention solves these problems and has excellent self-adhesiveness without adding a tackifier, as well as cuttability, strength and transparency during packaging, and microwave oven resistance. Excellent properties (heat resistance)
The purpose is to provide a self-adhesive film.

[Means for solving the problem] The present invention provides a self-adhesive film obtained by mixing and melting at least one selected from (b) to (d) for the following (a). It is something.

(a) Ethylene/α-olefin copolymer satisfying the following properties (I) to (III) obtained by copolymerizing X-tyrene and α-olefin having 3 to 12 carbon atoms.
80-20 parts by weight (I) Density 0.860
- less than 0.910 g/c+o3, (II) Maximum peak temperature measured by differential scanning calorimetry (DSC) of 100°C or more, (III) Boiling l1n-hexane insoluble content of 10 parts by weight or more.

(b) Ethylene with a density of 0.91-0.97 g/cm3.
α-olefin copolymer: 20 to 80 parts by weight (c) High-pressure polyethylene or its copolymer: 10 to 80 parts by weight (d) Propylene (co)polymer: 10 to 30 parts by weight The content of the present invention will be described in detail below. do.

(a) The α-olefin polymer in ethylene used in the present invention is a recently developed very low density polyethylene (VLDP).
E), more specifically, it is a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, and is a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms.
The present inventors have discovered that when this VLDPE is used as a material for a self-adhesive film, its excellent properties are exhibited and an excellent self-adhesive film can be obtained. completed.

The above VLDPE has a density of 0.8[i-0,910g/
cm3, has a maximum peak temperature (T, ) of 60°C or higher as measured by differential scanning calorimetry (DSC), and has a boiling point insoluble in Rn-hexane of 10% by weight or higher, which is similar to linear low-density polyethylene and ethylene. - It is a new polyethylene that exhibits properties intermediate to those of α-olefin copolymer rubber.

This VLDPE is a resin that has both the highly crystalline part shown by LLDPE and the amorphous part shown by ethylene-α-olefin copolymer rubber.
Heat resistance and the latter characteristics such as self-adhesiveness, rubber-like elasticity, and low-temperature impact resistance coexist in a well-balanced manner, making it extremely useful when used in the present invention.

As a specific α-olefin, propyref 1 1-
Butene, 4-methyl-1-pentene, 1-hexane, 1
-octene, 1-dodecene, and the like.

Among these, particularly preferred are 1-butene, 4-methyl-1-pentene, 1-hexane, and 1-octene. The α-olefin content in the ethylene copolymer is 5 to 4
Preferably it is 0 mol%.

mVLDPE can be produced using a catalyst system consisting of a solid catalyst component containing at least magnesium and titanium and an organoaluminium compound.

The solid catalyst component includes magnesium metal; magnesium hydroxide; magnesium oxide; magnesium salts such as magnesium chloride; double salts and double oxides containing elements selected from magnesium metal; magnesium hydroxide; magnesium chloride; silicon, aluminum, calcium; and magnesium carbonate; compounds, carbonates, chlorides, or hydroxides; and inorganic substances containing magnesium, such as those obtained by treating or reacting these inorganic solid compounds with oxidized compounds, sulfur-containing compounds, aromatic hydrocarbons, or halogen-containing substances. Examples include those in which a titanium compound is supported on a solid compound by a known method.

The oxygen-containing compounds mentioned above include, for example, water; nucleating oxygen-containing compounds such as alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, polysiloxanes, and acid amides; Examples include oxygen-containing compounds.

Examples of the sulfur-containing compound include organic sulfur-containing compounds such as thiol and thioether, and inorganic sulfur compounds such as sulfur dioxide, sulfur trioxide, and sulfuric acid.

Examples of aromatic hydrocarbons include various monocyclic, polycyclic, and polycyclic aromatic hydrocarbon compounds such as benzene, toluene, xylene, anthracene, and phenanthrene.

Examples of halogen-containing substances include compounds such as chlorine, hydrogen chloride, metal chlorides, and organic halides.

On the other hand, examples of the titanium compound supported on the inorganic solid compound containing Mg/U include titanium halides, Alfquine halides, alkoxides, and halogenated oxides. Preferred titanium compounds are tetravalent titanium compounds and trivalent titanium compounds, and specific examples of tetravalent titanium compounds include general formulas T and (OR).
,, X4-4 (where R represents an alkyl group, aryl group, or aralkyl group having 1 to 20 carbon atoms, X represents a halogen atom, and n is an integer of 0≦n≦4). Preferred are titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxymonochlorotitanium, tetramethoxytitanium, monoethoxytrichlorotitanium, jetoxydichlorotitanium, triethoxymonochlorotitanium, Tetraethoxytitanium, monoisopropoxytrichlorotitanium, noisobroboquine nochlorotitanium, triisopropoxymonochlorotitanium, tetraisopropoxytitanium, monobutoquinotrichlorotitanium, dibutoxydichlorotitanium, monopentoxytrichlorotitanium, monophenokiditrichlorotitanium , tetraphenoxy titanium, and the like. As trivalent titanium compounds, titanium tetrahalides such as titanium tetrachloride and titanium tetrabromide are combined with hydrogen, aluminum, titanium, or titanium of the periodic table I.
Examples include titanium trihalides obtained by reduction with organometallic compounds of group metals. Also - bottom T i (
OR), Nohalogenated arelecoquine titanium in the periodic table 1
~3 obtained by reduction with an organometallic compound of group m metal
Examples include titanium compounds with high valence.

Among these titanium compounds, tetravalent titanium compounds are particularly preferred.

As an example of other catalyst systems, reaction products of organomagnesium and titanium compounds, such as so-called Grignard compounds, can be used as solid catalyst components.

In addition, as an example of other catalyst systems, Si is used as a solid catalyst component.
It is also possible to use a solid material obtained by contacting an inorganic oxide such as O3 or A1°03 with the solid catalyst containing at least magnesium and titanium.

Specific examples of organoaluminum compounds to be combined with the above-mentioned solid catalyst components include - bottom R3A l;
R2A IX, RA IX2. R2A 1OR
, RAI (OR) Preferable are compounds represented by triethylaluminum, triisobutylaluminum, triethylaluminum, triethylaluminum, triethylaluminum,
Examples include trioctylaluminum, diethylaluminum chloride, diethylaluminum chloride, ethylaluminum sesquichloride, and mixtures thereof.

The amount of the aluminum compound to be used is not particularly limited, but it can usually be used in an amount of 0.1 to 1.000 times the amount of the titanium compound.

The polymerization reaction is carried out in the same manner as a typical olefin polymerization reaction using a Ziegler type catalyst. That is, all reactions are carried out substantially in the absence of oxygen, water, etc., in the gas phase or in the liquid phase in the presence of an inert solvent or in the monomer itself as the solvent. Olefin polymerization reaction occurs at a temperature of 20 to 300°
C1 is preferably 40 to 200°C, and the pressure is normal pressure to 70 kg/cm2G, preferably 2 kg/cm2G to 60 kg/cm2G. Although the molecular weight can be adjusted to some extent by changing polymerization conditions such as polymerization temperature and catalyst molar ratio, it is effectively achieved by adding hydrogen to the polymerization system.

A two-stage or more multi-stage polymerization reaction with different polymerization conditions such as hydrogen concentration and polymerization temperature can also be carried out without any problem.

(a) VLDPE, which is an ethylene/α-olefin copolymer used in the present invention, is obtained by using a conventional solid catalyst component mainly consisting of vanadium or a conventional solid catalyst component mainly consisting of titanium as a solid catalyst component. It is clearly distinguished from the ethylene/α-olefin copolymer. Even though the monomers constituting the copolymers are the same and the densities are the same, the copolymer of the present invention has a higher T by DSC, and the insoluble matter is higher than the copolymer of the present invention by DSC. While the copolymer has a content of 10% by weight or more, when a vanadium-containing catalyst or a conventional titanium-containing catalyst is used, the insoluble content is absent or is present in a very small amount.

It is important that the VLDPE of the present invention synthesized as described above has a density of 0.860 to 0.910 g/cm', preferably 0.880 to 0.905 g/cm'.
It is 3. Further, the maximum peak temperature (T1) determined by DSC needs to be 100°C or higher, preferably 110°C or higher.

Boiling in-hexane insoluble content (cEi insoluble content) is 10% by weight
The amount is preferably 20 to 95% by weight.

(b) The ethylene-α-olefin copolymer used in the present invention is produced by polymerization using a Ziegler catalyst consisting of a solid catalyst component containing at least titanium and/or vanadium and an organoaluminum compound. It ranges from known linear low density polyethylene (LLDPE) to high density polyethylene (HDPE), and has a density of 0.91 to 0.97 g/cm3, preferably 0.93 g.
/cm3 or more.

The (c) fRr pressure polyethylene or its copolymer used in the present invention is a known polyethylene obtained by high-pressure radical polymerization, and usually has a density of 0.910 to 0.
．． 940 g/cm3 and -) MFR of 5 or more and less than 20 is preferable. Examples of such copolymers include ethylene-vinyl ester copolymers such as ethylene-vinyl acetate copolymer (EVA), and ethylene-(meth)acrylic acid alkyl ester copolymers such as ethylene-ethyl acrylate copolymer (EEA). Examples include, but are not limited to, copolymers with ethylene-α, β-carboxylic acids or derivatives thereof, such as polymers.

As the polypropylene (co)polymer (d) used in the present invention, it is preferable to use a known homo to random type polypropylene (co)polymer having an MFR of 8 or more and 20 or less.

A film containing component (a) VLDPE alone of the present invention is suitable for use as a wrap film in that it has strong self-adhesiveness, but has a problem in that it lacks cuttability due to its high elongation and tear strength. On the other hand, components (b) to (d) have no adhesive properties and are therefore unsuitable for use as a wrap film alone, but (a)
When blended with component (a), the cutting properties are improved and the drawbacks of component (a) are compensated for. In addition, components (c) and (d) are used to further adjust the film's M (representing the flexibility of the film, and the relationship is such that the higher the tensile modulus, the greater the stiffness of the film) according to the intended use of the film. It can be blended to

If the MFR of components (b) to (d) is 20 g/10 minutes or more, the strength of the film decreases, which is not preferable. Also, (b) is added to 20 to 80 parts by weight of component (a).
The blending amount of the component is 20 to 80 parts by weight, the blending amount of the (c) component is 10 to 80 weight parts, and the blending amount of the (d) component is 10 to 30 parts by weight.
It is a part by weight and is appropriately selected from these ranges depending on the intended use.

The film of the present invention obtained by blending component (a) with at least one selected from components (b) to (c), mixing and melting, and forming a film can greatly exhibit the respective advantages of each component. It has good self-adhesiveness and transparency, excellent cuttability and microwave properties, and has a stiffness that suits the purpose of use, making it suitable for household and commercial wrapping films and masking films.

When mixing and melting the above components to form a film, antistatic agents, antifogging agents, inorganic or organic fillers, antioxidants, lubricants, organic or inorganic pigments, ultraviolet inhibitors, dispersants, Known additives such as plasticizers and nucleating agents can be added.

As a film forming method, the well-known inflation method, T-die method, etc. can be used, and an excellent self-adhesive film can be manufactured without using a specific film forming method.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Components (a) to (d) used in Examples and Comparative Examples are shown below.

Component (a): Ethylene/α-olefin copolymer (VLDPE) Using a solid catalyst obtained from substantially anhydrous magnesium chloride, 1,2-dichloroethane and titanium tetrachloride, and a catalyst consisting of triethylaluminum, Ethylene and 1-butene were copolymerized to obtain an ethylene@1-butene copolymer.

, :, (7) VLDPE Ha, 1-butene content = 10 mol%, density = 0.905 g/cm', T,
= 118°C, boiling C6 insoluble content = 60% by weight, MFR =
It was 10g/10mln.

Component (b): Ethylene/α-olefin copolymer (1) (LLD
PE-1) [Density=0.935g/cm3, MFR=10g/1
0m1n: Product name Nishiraishi Sunilex AJ5610, coethylene-α-olefin copolymer K (2) (LLDPE manufactured by Japan Petrochemical Co., Ltd.)
-2) [Density=0.923g/cm3, MFR=8g/10m
1n; Trade name Nishiraishi Sunilex AJ5310, manufactured by Nippon Petrochemical Co., Ltd.] Ethylene Φα-olefin copolymer (3) (HDP
E) [Density=0.948g/cm3, MFR=7g/10m
1n; Product name: Shiraishi Stuff L/7E870, manufactured by Nippon Petrochemicals Co., Ltd.] (c) Component: High pressure polyethylene (HPLDPE) [Density = 0.917g/cm3, MFR = 8g710m
in: Product name; Shiraishi Rexron J502, Japan Petrochemical Co., Ltd. Film production (d) Component: Polypropylene (PP) [Density = 0.905 g/cm', M F R, = 8 g
/10m1n: Product name: Shiraishi Volip OF 155J1 manufactured by Nippon Petrochemicals Co., Ltd.] (a) Method for measuring Tm and CG insoluble content of VLDPE: (Measurement method for T by DSC) 100 μm thick film formed by hot press molding Approximately 5m from
Weigh the sample accurately, set it on the DSC g, and
After raising the temperature to 0°C and maintaining the same temperature for 15ml, it was cooled to O'C at a cooling rate of 2.5°C/min. Next, from this state, the temperature is raised to 170'C at a heating rate of 10°C/min. That's it.

(Measurement method for boiling CG insoluble content) A sheet with a thickness of 200 μm is formed using a heat press, and three 7-sheets of 20 mm x 30 mm are cut out from the sheet.
- Perform a 5 hr extraction with hexane. After taking out the n-hexane insoluble content and vacuum drying (7 hours at 150°C), the C6 insoluble content (41%) was calculated using the following formula.

Films were prepared using the respective components used in the present invention alone or in combination, and their performance was measured.

Details of the film forming apparatus, conditions, and physical property test method are as follows.

Molding g position and conditions Extruder Tanabe Kikai 50rnrnΦ extruder screw L/D=22 full flat type die 600
Coat hanger die cooling in mm Roll cooling method Extrusion temperature 250°C Film forming speed 30 m/min Film thickness 10-13 μm Physical property test method Haze (%): J Is KE3714 Tensile strength at break: 〃 Tensile elongation at break: 〃 Tensile modulus : Microwave suitability: The state of the film was visually observed after actual cooking using a Mitsubishi Electric microwave oven model RO-1000.

The test results are shown in the table.

Wrap property 2: Layer 1 petrochemical method film width 15 mm x 20 mm, apply a load of 5 kg, leave it in a constant temperature and humidity room at 23 degrees Celsius for 24 hours, and then determine the 90' peel strength in a tensile test. Numerical values were used.

Cutability: Evaluation was made using a saw blade of a commercially available wrap film.

[Effects of the Invention] The self-adhesive film of the present invention has a specific ethylene-α-
Ultra-low density polyethylene (V
LDPE) with a density of 0.91 to O-97g/cm
No. 3 ethylene/α-olefin copolymer (LLDPE-
HDPE), high-pressure polyethylene or its copolymer (
HPLDPE) and propylene (co)polymer (PP)
By using a composition containing a specific amount of at least one (co)polymer selected from It is possible to calculate the waist (tensile modulus) by H node. Therefore, it is effectively used as a household and commercial wrap film, a masking film, etc.

Applicant: Japan Petrochemical Co., Ltd.

Claims (1)

[Claims] (1) A self-adhesive film obtained by mixing and melting at least one selected from (b) to (d) with (a) below. (a) 80 to 20 parts by weight of an ethylene/α-olefin copolymer that satisfies the properties (I) to (III) below, obtained by copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms (I ) Density of 0.860 to less than 0.910 g/cm^3, (II) Maximum peak temperature measured by differential scanning calorimetry (DSC) of 100°C or more, (III) Boiling n-hexane insoluble content of 10 parts by weight or more. (b) 20 to 80 parts by weight of ethylene/α-olefin copolymer with a density of 0.91 to 0.97 g/cm^3 (c) High pressure polyethylene or its copolymer 10 to 8 parts by weight
0 parts by weight (d) 10 to 30 parts by weight of propylene (co)polymer