JPH02283740A - Polyolefin composition for shrinking film - Google Patents

Abstract

PURPOSE:To obtain a composition having excellent heat-shrinking properties and weathering resistance by mixing a crystalline propylene/alpha-olefin copolymer with a petroleum resin, a hindered amine light stabilizer and a benzonitrile light stabilizer. CONSTITUTION:A polyolefin resin composition prepared by mixing 100 pts.wt. composition, prepared by mixing a crystalline propylene/alpha-olefin copolymer of a crystalline melting point of 115-145 deg.C with 35-5wt.% petroleum resin, with 0.3-0.6 pt.wt. hindered amine light stabilizer and 0.1-0.5 pt.wt. benzonitrile light stabilizer. When the copolymer used has a crystalline melting point >145 deg.C, the heat-shrinking properties of a stretched film is poor. When the crystalline melting point is below 115 deg.C, the composition is not desirable because of problems such as blocking between stretched films and sticking to a casting roll during film formation before stretching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyolefin composition for use in shrink films that has excellent weather resistance and high heat shrinkability.

[Conventional technology]

Conventionally, polystyrene resins and vinyl chloride resins are well known as this type of shrink film composition. However, stretched films made from polystyrene resins have poor impact resistance, and stretched films made from vinyl chloride resins have drawbacks in that hydrogen chloride gas is generated when incinerated. On the other hand, polypropylene-based stretched films obtained from propylene homopolymer resins, ethylene-propylene copolymer resins containing propylene as the main component, and ethylene-propylene-butene copolymer resins are superior to those obtained from polystyrene resins and vinyl chloride resins. Since it does not have the above-mentioned drawbacks and has excellent heat resistance, it is also used as a shrink film for retorts and other applications.

However, the polypropylene-based stretched film has a drawback that its shrinkage rate after heating (heat shrinkability) is smaller than stretched films obtained from polystyrene resins or vinyl chloride resins.

Conventionally, in order to increase the heat shrinkability of a stretched polypropylene film, a method has been proposed in which a stretched film is made using a polyolefin composition in which a petroleum resin is added to a polypropylene resin (Japanese Patent Laid-Open No. 4735/1989). Public bulletin).

However, the reality is that with this method, the weather resistance of the stretched film obtained by adding petroleum resin is extremely reduced, and the film is susceptible to deterioration by ultraviolet rays, etc., greatly limiting its practical use.

[Problem to be solved by the invention]

The present inventor conducted extensive research in order to obtain a polypropylene composition that can yield a shrink film that has high heat shrinkability and excellent weather resistance. As a result, the crystal melting point is 115~
By using a composition consisting of a propylene-α-olefin copolymer at 145°C and a specific petroleum resin, a combination of a specific light stabilizer and a specific value of an ultraviolet absorber is added. The present invention was completed based on the discovery that a film having weather resistance and high heat shrinkability can be obtained.

As is clear from the above description, an object of the present invention is to provide a polyolefin-based resin composition for shrinkable films, from which a stretched film having high heat shrinkability and excellent weather resistance can be obtained.

[Means to solve the problem]

The present invention has the following configuration.

(1) 0.3 to 0.3 parts by weight of a hindered amine light stabilizer per 100 parts by weight of a composition in which a crystalline propylene-α-olefin copolymer with a crystalline melting point of 115 to 145°C is blended with 35 to 5 parts by weight of petroleum resin. A polyolefin resin composition for a shrink film, which contains 0.6 parts by weight and 0.1 to 0.5 parts by weight of a benzotriazole light stabilizer.

The propylene-α-olefin copolymer used in the present invention has a propylene component of 70 times! It is a copolymer of propylene containing -% or more and ethylene and/or an α-olefin having 4 to 8 carbon atoms, preferably an ethylene-propylene-butene-1 copolymer with a crystalline melting point (hereinafter referred to as T
It's called m. ) is 115-145°C. Here, Tm refers to the peak temperature of an endothermic curve associated with melting of a crystal obtained by heating a sample at a rate of 20° C./min in a nitrogen atmosphere using a scanning differential calorimeter. When a propylene-α-olefin copolymer with a Tm of more than 145°C is used, the resulting stretched film has poor heat shrinkability when the resulting composition is made into a stretched film, and a copolymer with a Tm of less than 115°C If this method is used, problems such as blocking between the stretched films when the obtained composition is made into a stretched film and adhesion to the casting roll occur when forming the film before stretching (hereinafter referred to as the original film). So I don't like it. Petroleum resins as used in the present invention mean hydrocarbon resins, including coke oven gas, coal tar fraction cracked and deep cracked petroleum feedstocks, essentially pure hydrocarbon feedstocks or hydrocarbon feedstocks derived from turpentine or It refers to a hydrocarbon polymer derived from turpentine oil, and typical hydrocarbon resins include, for example, coumaron-indene resin, petroleum resin, styrene resin, cyclopentadiene resin,
Examples include terpene resins. Coumaron-indene resins are hydrocarbon resins, phenol-modified coumaron-indene resins or derivatives thereof, obtained by polymerization of resin formations present in the distillate of coal tar recovered from coke ovens. Petroleum resins refer to hydrocarbon resins obtained by catalytic polymerization of deeply cracked petroleum raw materials, and these petroleum raw materials generally include styrene, methylstyrene, vinyltoluene, indene, methylstyrene-butadiene, isoprene, piperylene, pentylene, etc. Contains a mixture of resin formulations.

Styrene resin is a low molecular weight homopolymer resin of styrene, such as styrene and α-methylstyrene, vinyltoluene, etc.
It is a copolymer resin with butadiene, etc.

The cyclopentadiene resin is a cyclopentadiene homopolymer resin or copolymer resin derived from coal tar fraction or separated petroleum gas, and the cyclopentadiene resin is a cyclopentadiene-containing raw material that is heated to a high temperature. It is produced by holding it for a long time, and depending on the holding temperature, either a dimer, a 3i monomer, or a high polymer can be obtained.

Terpene resins are polymers of terpenes, which are hydrocarbons of the characteristic formula C1°H3, present in most essential oils and plant oleoresins, and phenol-modified terpene resins, such as α-pinene, β - Pinene, dipentene, limonene, myrcene, bornylene, camphene and similar terpenes.

Among these petroleum resins used in the present invention, the softening point is 8.
Particularly preferred are hydrogenated petroleum resins that exhibit transparency at 0 to 165°C, such as hydrides of aromatic hydrocarbon resins and hydrides of terpene resins. These petroleum resins may be commercially available products, such as Alcon (trademark) P-115, P-Ko 25, P-140 from Arayo Kagaku ■, and Yasuhara Chemical ■.
Examples include Clearon (Commercial 1) P-125, )-Jx's Escolette (trademark) 5320.

The addition ratio of the petroleum resin is such that the crystal melting point is 115 to 145°C.
5 to 35% by weight based on the composition comprising the crystalline propylene-α-olefin copolymer and the petroleum resin.

If the addition ratio is less than 5% by weight, the stretched film will have low heat shrinkability when made from the final composition, and if it exceeds 355 parts by weight, the final composition will not be used to produce a raw film. This is not preferable because it tends to stick to the casting roll when doing so.

The hindered amine light stabilizer (hereinafter referred to as compound (1)) used in the present invention contains a hindered amine nitrogen atom and any other atom, preferably nitrogen or oxygen.
It consists of a membered heterocycle, specifically, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-bentamethyl-4-piperidinyl) )-2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and amber Polyester with acid, (4-(4-hydroxy-3,5-di-t-butylphenyl)propionyl)-N-(4-hydroxy-3,5
-di-t-butylphenyl)methyl-2゜2,6.6-
Tetramethylbiperidine, bis(N-methyl-2,2,
6,6-titramethyl-biperidinyl)sepacate, tetrakis(2,2,6,6-tetramethyl-4-piperidinyl)-1,2,3,4-butanetetracarboxylate, poly((6-(1 , 1,3,3-tetramethylbutylimino)-1,3,5-)riazine-2,4-diyl] [
4-(2,2,6,6-titramethylpiperidinyl)-
imino) -(4-2,2,6,6-titramethylpiperidinyl)-imino]), poly([6-morpholino-2,4-diyl][4-(
2,2,6,6-titramethylpiperidyl)imino-hexamethylene) (4-(2,2,6,6-titramethylpiperidyl)imino]), phenyl-4-piperidinyl carbonate, 1,1' −
(1,2-ethanediyl)bis(3,3,5,5-tetramethylpiperazinone), 2,2.6.6-tetramethyl-4-piperidyl/tridecyl (mixed)-1,2,3,4 -butanecarboxylate, 1,2.2.6.6-bentamethyl-4-piperidyl/
Tridecyl (mixed)-1,2,3,4-butanetetracarboxylate, 2,2.6.6-tetramethyl-4-piperidyl/suβ
.

β2β′-tetramethyl-3,9-(2,4,8,10
-Tetraoxaspiro(5,5)undecanefudiethyl (mixed)-1,2,3,4-butanetetracarboxylate, 1,2.2.6.6-bentamethyl-4-piperidyl/β.

β, β and β′-tetramethyl-3,9-(2,4,8,
Examples include 10-tetraoxaspiro(5,5)undecanefudiethyl (mixed)-1,2,3,4-butanetetracarposilate. The addition ratio of the compound (I) is 0.3 to 0.6 parts by weight per 100 parts by weight of the composition containing the above-mentioned crystalline propylene-α-olefin copolymer and 5 to 35 parts by weight of petroleum resin. be. The addition ratio is 0.
If it is less than 3 parts by weight, the effect of improving weather resistance is small;
Even if more than 6 parts by weight is added, the effect of improving weather resistance reaches a ceiling and is uneconomical.

The benzotriazole light stabilizer used in the present invention (hereinafter referred to as
It is called compound G[). ) is 2-(2'-hi)'
Roxy5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-octylphenyl)
Benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-
methylphenyl)-5-chlorobenzotriazole, 2
- (2'-hydroxy-3f5'-di-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3:5'-di-t-butylphenyl)-5-chlorobenztriazole, 2- (2
'-hydroxy-3,'daidi-t-amylphenyl)
Penztriazole, 2-(2'-1)'Rot-C 3; 6'-Dicumylphenylphenylbenzotriazole, 2-(2'-Hydroxy-4'-octoxyphenyl)benzotriazole, 2-2' -methylenebis(4-(1,1,3.
3-tetramethylbutyl)-6-(2N-benzotriazol-2-yl)phenol] and the like. The addition ratio of the compound (1) is 5 to 50% of the petroleum resin to the above crystalline propylene-α-olefin copolymer.
0.35% by weight per 100 parts by weight of the composition.
It is 1 to 0.5 parts by weight. The addition ratio is 0. If it is less than 1 part by weight, there is no effect of improving weather resistance, and even if it is added in excess of 0.5 part by weight, the effect of improving weather resistance reaches a ceiling, resulting in cine economy.

The method for producing the composition of the present invention includes: (1) predetermined amounts of crystalline propylene-α-olefin copolymer, various heat stabilizers, lubricants, petroleum resins, hindered amine light stabilizers, and benzotriazole light stabilizers; Method of mixing with a Henschel mixer (trade name), super mixer, tumbler mixer, etc. ■Crystalline propylene-α-olefin copolymer, various heat stabilizers, lubricants, petroleum resins, hindered amine stabilizers, and benzotriazole A method in which a predetermined amount of system stabilizer is mixed using a Henschel mixer (trade name), super mixer, tumbler mixer, etc., and then pelletized using a granulator. ■ Various heat stabilizers are added to crystalline propylene-α-olefin copolymer. , lubricant, petroleum resin,
Examples include a method in which a hindered amine light stabilizer and a benzotriazole light stabilizer are individually added and pelletized, and then the pellets are blended at the above-mentioned blending ratio (pellet blending). The method for producing a stretched film using the composition of the present invention includes, for example, composition t of the present invention, melt cross-wire extrusion at a temperature higher than the melting point of the crystalline probylene-no-α-olefin copolymer used,
A sheet-like raw fabric is formed by rapidly cooling it in a cooling roll or a water tank, and in the case of an axially stretched film, this raw fabric (usually 100 to 1000μ in thickness) is stretched in the longitudinal direction and the transverse magnification is 3. ~10 times, in the case of a biaxially stretched film, the magnification in at least one of the longitudinal or transverse directions is set to 3 times or more, so that the difference in refractive index between the longitudinal direction or the transverse direction and the thickness direction is at least ioox An example of this method is to stretch each film so that the length is greater than or equal to to-'. If the difference in refractive index is smaller than the lower limit, the resulting stretched film will have a small shrinkage rate, which is not preferable. The preheating temperature when stretching the raw film is 50 to 150°C, and the stretching temperature is 60 to 1
Preferably, the temperature is 50°C and the fixed temperature is 30 to 100°C.

〔Example〕

Hereinafter, the present invention will be specifically explained using Examples and Comparative Examples, but the present invention is not limited thereto. The evaluation method used in Examples and Comparative Examples was as follows.

(1) Refractive index: Using Atsube's refractometer, using Na-D rays as the light source, using benzyl alcohol as the mound liquid, and changing the polarizing plate of the eyepiece, the refractive index in the vertical, horizontal, and thickness directions was measured using the total internal reflection method. Then, a value obtained by subtracting the refractive index in the thickness direction from the refractive index in the longitudinal direction or a value obtained by subtracting the refractive index in the thickness direction from the refractive index in the transverse direction is calculated.

(2) Weather resistance test method: Evaluation was carried out by accelerated weather resistance test using Suga Test Instruments KK Sunshine Super Long Life Weather Meter.

(The test piece dimensions are 200wX400+zaX
The temperature of the black panel plate was 63°C at 50p, and the spraying was carried out for 12 minutes per hour. ) The weather resistance was evaluated based on the weathering time required until appearance abnormalities such as cracks appeared on the surface of the test piece or until cracks appeared in the test piece when the test piece was bent.

(3) Heat shrinkability: A 100+m×10g 1K test piece is immersed in a glycerin solution at a temperature of 100° C. for 30 seconds, then quickly taken out and washed with pure water. The length in the longitudinal direction is measured and the shrinkage rate is calculated.

Examples 1 to 4, Comparative Examples 1 to 6 Crystalline ethylene-propylene-butene-1 random copolymer (ethylene content: 3.8% by weight, butene content 4.5% by weight, melt flow rate 5.f/10 Minutes, Tm130
℃) 700 parts by weight Aruyo Kagaku ■ Alcon P-14030
0.2 parts by weight of stearic acid and tris( 0.1 part by weight of 2,4-di-t-butylphenyl) phosphite and compound (1)
As A, poly((6-(1,1,3,3-tetramethylbutylimino)-1,3,5-)riazine-2,4-
As compound (1) B, 4-hydroxy-2,2,6,6-tetramethyl-1-
Polyester of piperidine ethanol and succinic acid, and compound ω), 2-(2'-hydroxy-3'-t-butyl-5'-
Methylphenyl)-5-chlorobenzotriazole was added to a Henschel mixer (trade name) at the addition rate listed in Table 1 below, and after stirring and mixing for 3 minutes, the shark mixture was heated to a melt crosstalk temperature of 180 using a granulator. The mixture was melt-mixed and extruded at ℃ to pelletize it. Each pellet obtained was
Using an extruder with a 0mx T-die, the melt crosstalk temperature was 180°C.
Each sheet was melt-cross-extruded and had a thickness of 250 μm. Each of the obtained sheets was then stretched 5 times in the transverse direction using a stretching machine at a stretching temperature of 80° C. to produce a stretched film with a thickness of 50 μm. Predetermined test pieces were cut out from the obtained stretched film and subjected to measurement of refractive index, weather resistance test, and heat shrinkability test. In addition, the difference in refractive index in the lateral direction and the thickness direction was calculated.

The evaluation criteria for weather resistance is 150 hours or more of weather resistance.
, 100 hours or more and less than 150 hours was Δ, and less than 100 hours was rated ×. The results are shown in Table 1.

Examples 5 to 8, Comparative Examples 7 to 12 As Examples 5 to 8, the thickness was 25% based on Examples 1 to 4.
A sheet with a thickness of 0 μm was prepared, and the sheet was stretched at a stretching temperature of 80 μm.
A stretched film having a thickness of 50 μm was prepared by stretching the film 5 times in the longitudinal direction at °C.

In addition, as Comparative Examples 7 to 12, sheets with a thickness of 250 μm were prepared according to Comparative Examples 1 to 6, and using the sheets, the sheets were stretched 5 times in the longitudinal direction according to Examples 5 to 8 to obtain a sheet with a thickness of 50 μm. A stretched film was created.

Predetermined test pieces were cut out from each of the stretched films obtained in Examples 5 to 8 and Comparative Examples 7 to 12, and a refractive index measurement, a weather resistance test, and a heat shrinkability test were conducted. In addition, the difference in refractive index in the longitudinal direction and the thickness direction was calculated. Note that the weather resistance evaluation criteria were based on Examples 1 to 4.

The results are shown in Table 2.

〔Effect of the invention〕

The stretched film obtained using the composition of the present invention has a very high heat shrinkage rate, and can be shrink-wrapped even at low temperatures.It also has excellent weather resistance, so it can be used for shrink-wrapping products such as juices, soft drinks, and cup noodles. It can be suitably used as a label or shrink wrapping film.

that's all

Claims (1)

[Claims] (1) 35 to 5% by weight of petroleum resin to crystalline propylene-α-olefin copolymer with a crystal melting point of 115 to 145°C
A shrink film obtained by adding 0.3 to 0.6 parts by weight of a hindered amine light stabilizer and 0.1 to 0.5 parts by weight of a benzotriazole light stabilizer to 100 parts by weight of a composition containing Polyolefin resin composition for use.