JPH0781044B2 - Antistatic film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention imparts antistatic properties by using a composition in which a specific blending component is blended with a specific ethylene polymer in a specific ratio. The present invention also relates to an antistatic film having a good balance of transparency, blocking, hue and printability.

(Prior Art) New low-density polyethylene, so-called linear low-density polyethylene, is being utilized in various fields as an alternative to conventional polyethylene or for new demand as its practical application progresses.

An attempt was made to form this linear low-density polyethylene into a film for the purpose of using it for various packaging materials, etc. In addition to the well-known T-die molding method and water-cooled inflation molding method, a quenching air ring was provided. Air-cooled inflation molding method (for example, JP-A-53-146764 and JP-A-58-21).
When a general-purpose processing method (see Japanese Patent No. 2918) is used, transparency can be greatly improved as compared with conventional polyethylene, but on the other hand, defects such as poor blocking property and slip property are recognized.

For this reason, it has been attempted to improve by blending an anti-blocking agent or a slip agent that does not significantly impair the transparency (see, for example, JP-A-59-22944).

(Problems to be solved by the invention) However, even if a film molded by such a method is applied to applications such as automatic packaging and hand-packed packaging, since the film is often charged, packaging mistakes frequently occur, which makes it impractical. Absent.

Therefore, in order to put such a film into practical use, it is a conventional means to add an antistatic agent, but if an antistatic agent which is usually commercially available is simply added to the linear low density polyethylene, Yellowing of the film occurs over time, resulting in a significant decrease in commercial value, or even if the initial antistatic property can be imparted, the antistatic property of the film decreases over time and the suitability for automatic packaging becomes poor. In the film printing process, clogging of the printing roll or peeling of the printing may occur, making stable production impossible for a long period of time, or blocking property over time becomes poor, so the bag mouth will not open and automatic filling errors will occur frequently. If you do so, or if you stack the molding bags on top of each other, they will come into intimate contact with each other to form a plate, making it completely unusable.

It turned out that troubles occur with.

(Means for Solving the Problem) [Summary of the Invention] The inventors of the present invention have investigated the cause of such a phenomenon. As a result, the boiling hexane-soluble component of the base resin, an antistatic agent and thermal stability are imparted. It was found that this is caused by the antioxidant that is blended for that reason.

The present invention aims to eliminate such drawbacks,
It was made by finding that these objects can be achieved by using a specific polymer, an anti-blocking agent, an antioxidant and an antistatic agent.

That is, the antistatic film of the present invention, the boiling hexane-soluble content at a melt index of 10 g / 10 minutes or less and 20% by weight or less and a density of 0.91 to 0.94 g / cm ³ of ethylene / α-olefin copolymer 100 parts by weight. In addition, 0.015 to 1 part by weight of a predetermined amount of each of the following components (a) to (d) and the total amount of the components (b), (c) and (d), and the components (c) and (d). The weight ratio (c) component / (d) component of the composition is in the range of 3/7 or less.

(A) Anti-blocking agent 0.01 to 1 part by weight (b) Phenolic antioxidant with a molecular weight of 500 or more 0.005
By weight or more (c) Polyoxyethylene alkylamine 0.005 parts by weight or more (d) Glycerin monofatty acid ester 0.005 parts by weight or more [Detailed description of the invention] [I] Film composition (1) Constituent component (essential component) The antistatic film of the invention is one in which the ethylene polymer which is the main constituent material of the film has specific physical property values, and is composed of a composition in which specific additives are added to such an ethylene polymer. .

Ethylene Polymer The ethylene polymer used in the present invention has a melt index (MI) of 10 g / 10 minutes or less, preferably 0.01 to 5 g / 10 minutes, and a boiling hexane-soluble content of 20% by weight or less, preferably 15%.
% Or less, most preferably 10% or less, and a density of 0.91 to 0.94 g / cm ³ , preferably 0.915 to 0.935 g.
/ cm ³ of ethylene / α-olefin copolymer.

Such an ethylene / α-olefin copolymer is produced by so-called ionic polymerization, and includes propylene, butene-1, hexene-1, 4-methylpentene-
Generally, a copolymer containing about 0.1 to 15% by weight of an α-olefin such as 1, octene-1 (preferably having about 3 to 10 carbon atoms) is used. Such a copolymer itself is well known and can be appropriately selected and used from commercially available products.

In the case of copolymers out of the above range, the effect is small, and even the blocking property immediately after molding becomes unsatisfactory,
The transparency, rigidity, impact strength or workability of the film may be insufficient, which is not preferable.

Anti-blocking agent The anti-blocking agent used in the present invention is, for example, inorganic powder such as silicon dioxide, zeolite, talc,
These may be used alone or in combination.

Silicon dioxide having an average particle size of 10 μm or less, particularly 5 μm or less is preferable in terms of transparency and visible defects of the film. As the silicon dioxide, either natural silica or synthetic silica may be used, and particularly commercially available products such as "Syloid 66" and "Syloid" are used.
244 ”(manufactured by Fuji Devison Co., Ltd.) and the like are preferably used.

Zeolite and talc have an average particle size of 20μ or less, especially 5μ
The following are preferable from the viewpoint of visible defects of the film. Zeolites may be natural or synthetic. Among them, the combined use of zeolite and talc is preferable, and the combined use of zeolite and talc in the ratio of 1: 9 to 9: 1 is particularly preferable in that there is no blocking property or whitish immediately after molding.

Phenolic antioxidant The phenolic antioxidant used in the present invention has a molecular weight of 50.
It is a compound of 0 or more, preferably 690 or more.

Examples of such compounds include, for example, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6. -Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,
5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 1,3,5-tris (2-hydroxyethyl) -S-triazine-2,4,6 (1
H, 3H, 5H) -Trione and 3,5-di-t-butyl-4-hydroxy-hydrocinnamic acid triester, 1,6
-Hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2-
Thio-diethylenebis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), triethyleneglycol-bis [3- (3-t-butyl) -5-methyl-4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,1,3-
Examples include tris (2-methyl-4-hydroxy-5-t-butylphenol) butane and tris [β- (3,5-di-t-butyl-4-hydroxyphenylpropionyl-oxyethyl] isocyanurate. You can also do it.

In addition, with a phenolic antioxidant having a molecular weight smaller than the above range, the temporal blocking property is deteriorated.

Polyoxyethylene alkylamine The polyoxyethylene alkylamine used in the present invention is
It has the following molecular structure.

Here, R ¹ is an alkyl group and preferably has a carbon number.
12 to 24, particularly preferably 16 to 22. The degree of polymerization n and m of the oxyethylene group are each preferably 1
-5, particularly preferably 1-2. These can be used together.

Glycerin Monofatty Acid Ester The glycerin monofatty acid ester used in the present invention has the following general formula.

Here, R ² is an alkyl group, and preferably has a carbon number of
12 to 24, particularly preferably 16 to 22.

(2) Blending ratio The blending amount of each of the above components is 0.01 to 1 part by weight, preferably 0.1 to 0.6 part by weight, of the anti-blocking agent as the component (a) with respect to 100 parts by weight of the ethylene / α-olefin copolymer. Is.

If it is less than this range, the antiblocking property and antistatic property are not satisfactorily achieved, and if it exceeds this range, the transparency, printability and antistatic property become insufficient.

Further, the component (b) a phenolic antioxidant having a molecular weight of 500 or more, the component (c) polyoxyethylene alkylamine and the component (d) glycerin monofatty acid ester are
0.005 parts by weight or more, preferably 0.01 parts by weight or more, respectively, and the total amount of phenolic antioxidant having a molecular weight of 500 or more, polyoxyethylene alkylamine and glycerin monofatty acid ester compound is 0.015 to 1 part by weight, preferably Is in the range of 0.05 to 0.6 parts by weight.

When the components other than the anti-blocking agent are less than the above range, the effect of antistatic property is not exhibited, while when the components are excessive, transparency and blocking properties are deteriorated or bleeding is not preferable. Further, if the glycerin monofatty acid ester is removed from the above-mentioned composition, the effect of antistatic property is imparted, but the film is blocked with time or remarkably yellowed and cannot be used. Also,
When polyoxyethylene alkylamine is removed from the above composition, a good effect is exhibited for blocking with time, but the effect of antistatic property is insufficient, and the antistatic property is lowered particularly with time. Then it cannot be used for practical purposes. It is preferable to use a composition in which the weight ratio of polyoxyethylene alkylamine and glycerin monofatty acid ester is 3/7 or less. If the weight ratio is more than the above, the effect of blocking the film over time is not exhibited, and the film becomes yellow with time and cannot be used. When the molecular weight of the phenolic antioxidant used for the purpose of imparting thermal stability is less than the above range, the effect of blocking with time is not exhibited, and the target blocking property with time cannot be set.

(3) Auxiliary component (optional component) The composition which is a raw material of the antistatic film of the present invention basically comprises the above-mentioned essential components, but the composition is optional in addition to these essential components. It is possible to mix the additional components of the above in a range that does not significantly impair the effects of the present invention.

As an auxiliary component or an additional component, other antistatic agents,
Other stabilizers such as antioxidants, antifog agents, ultraviolet absorbers, nucleating agents, additives such as slip agents, high-pressure low density polyethylene, high density polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer Other polymers such as ethylene / propylene-based copolymer rubber can be mentioned. In particular, higher alcohols (C12
The above chain alcohol) is preferably added in terms of the number of polyoxyethylene alkylamines added in the composition in terms of the balance between antistatic property and blocking property of the film, but higher alcohols (compounds having 16 to 22 carbon atoms, These may be used in combination) with the polyoxyethylene alkylamine of the component (c) at 1:10 to 5: 1 (1 part by weight of the polyoxyethylene alkylamine of the component (c)) with 0.1% of the higher alcohol. Particularly good results are obtained when used in combination within the range of up to 5 parts by weight). Also, the melt index
30 g / 10 minutes and density 0.935 g / cm ³ or less, preferably 0.922
~ 0.935 g / cm ³ , high pressure polyethylene
30 parts by weight or less, preferably 5 to 30 parts by weight per 100 parts by weight of the α-olefin copolymer, the transparency of the film when blended,
In addition to rigidity, it is preferable in terms of processability (film forming stability, extrusion characteristics). Further, as the organic amide compound, unsaturated fatty acid amides (erucic acid amide, oleic acid amide, etc.) and saturated fatty acid amides (stearic acid amide, behenic acid amide, etc.) are used alone or in combination, and the ethylene / α-olefin copolymer is used. It is preferable to add 0.01 to 1 part by weight, preferably 0.05 to 0.3 part by weight to 100 parts by weight, from the viewpoint of the slip property of the film. Particularly good results are obtained when unsaturated fatty acid amides are used together in a ratio of 1: 20 to 10: 1. In addition to the above, it is preferable that 0.01 to 0.5 parts by weight of an organic phosphorus compound is blended as a heat stabilizer with respect to 100 parts by weight of the ethylene / α-olefin copolymer in terms of film hue and blocking.
In particular, 0.02 to 0.3 of at least one compound selected from phosphonite, phosphite, and phosphonic acids is used with respect to 100 parts by weight of the ethylene / α-olefin copolymer.
It is advisable to blend in parts by weight.

[II] Production of Film The composition is preferably obtained by blending the above components in the above proportions and pelletizing with an ordinary mixing / kneading machine.
The masterbatch or the compound directly may be film-formed by a molding machine.

Film formation can be performed by any purposeful method. For example, any of inflation molding, T-die molding, calender molding and the like are suitable.

(Example) [I] Raw materials The additive components in the table are as follows.

(1) Phenolic antioxidant A: pentaerythrityl-tetrakis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate]: molecular weight 1176.6 B: octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate: molecular weight 530.8 C: 2.6-di-t-butyl- 4-Methylphenol: molecular weight 220.6 (2) Polyoxyethylene alkylamines A: N, N'-bis (2-hydroxyethyl) octadecylamine B: N, N'-bis (2-hydroxyethyl) docosylamine C: octadecyl Diethanolamide (3) Glycerin monofatty acid esters A: Glycerin monostearate B: Glycerin monostearate (4) Higher alcohol A: C ₁₈ H ₃₇ OH B: C ₂₂ H ₄₅ OH [II] Evaluation method (1) Temporal blocking Before measuring the test piece at 40 ℃, 60% RH, 50g / cm ² high temperature and high load After pressing down to promote film adhesion for 7 days,
Using a tensile tester, the maximum stress required to peel off 10 cm ² of the film adhesive surface at a tensile speed of 500 mm / min (g
/ 10 cm ² ).

(2) Film hue b value The hue (Y, Z values) of the end surface of the film wound in a cylindrical shape after being aged for 7 days at 40 ° C. and 60% RH is JIS-K71.
It is measured according to 03 and is shown by the b value shown in the following equation.

(3) Half-life of electrified voltage Using a static Honest meter, find the time t (seconds) from when the constant voltage of 10 KV was stopped until the initial charge recorder display voltage became 1/2.

The operation of the Honest meter is to apply a voltage of 10 KV from 2 cm above the test piece of 30 × 40 mm for 2 minutes while rotating the turntable at 1550 rpm (60 Hz), turn off the applied voltage, and then turn the turntable 3 The procedure of recording the minute decay curve was followed. The test pieces used were those aged at 40 ° C. and 60% RH for a predetermined period.

(4) Tobacco ash adhesion measuring method Three pieces of 100 mm × 400 mm size film are lightly rubbed three times with gauze or wool, and this is brought closer to pre-dried tobacco ash from above. At this time, the height of the film on which the ash rises and adheres is read on a scale, and the height is shown in the following four stages.

○: Less than 1 cm △: 1 or more and less than 5 cm ×: 5 or more and less than 15 cm XX: 15 cm or more The melt index (MI) is ASTM D1238 (190
° C), and the boiling hexane-soluble content was determined by the following method. The ethylene copolymer was extracted with a high temperature Soxhlet extractor for 3 hours, and the weight percentage of the substance dissolved in boiling hexane with respect to the original sample is shown as the hexane-soluble content (% by weight). The ethylene copolymer used here was in the form of powder having a maximum particle size of 500 μ or less.

[III] Experimental Examples Examples 1 to 8 and Comparative Examples 1 to 13 Preparation of Compositions First, among the compounding components listed in Tables 1 and 2, an ethylene polymer and an antiblocking agent (zeolite: silica = 4: 1) were prepared. After mixing the mixture in the weight ratio with a Henschel mixer, the remaining components were further added and mixed, and the mixture was pelletized at a temperature of 190 ° C with an extruder with a screw diameter of 50 mm and L / D = 24. To make the composition.

Molding This composition was prepared by using an air-cooled inflation extruder for linear ethylene polymers using a double air slit air ring (40
mm diameter, screw L / D18) and spiral die 75 mm diameter (lip width 3 mm) are used to extrude a film thickness of 70 μ at 200 ° C. The blow ratio at this time was adjusted to 2.0.

Evaluation The quality of the film thus obtained was evaluated based on the following measuring methods. The evaluation results are shown in Tables 3 and 4.

[Advantages of the Invention] The antistatic film of the present invention is imparted with appropriate antistatic properties (the deterioration of the electrification property over time is also improved), and there is no change in the hue of the film over time, and a printing machine. There is no trouble such as clogging of the film, and not only the waste of the formed film due to the blocking of the film is prevented, but also when it is stacked and placed later in the suitability for automatic packaging using the film product and the storage of the film product later. There is no problem that automatic filling errors occur frequently due to the plate shape and the bag mouth not opening, and workability and storability are significantly improved.

It is surprising that such an excellent effect is exhibited by employing the specific polymer and the additive used in combination.

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Claims (1)

[Claims] 1. A boiling hexane soluble content of 20% by weight or less and a density of 0.91 to 0.94 g / cm with a melt index of 10 g / 10 min or less.
^In 100 parts by weight of the ethylene / α-olefin copolymer of ³ , each of the following components (a) to (d) in a predetermined amount and (b) and (c)
And 0.015 to 1 part by weight of the total amount of the component (d), and
A weight ratio of component (c) and component (d) (c) component / (d) component comprising a composition blended in a range of 3/7 or less. (A) Anti-blocking agent 0.01 to 1 part by weight (b) Phenolic antioxidant with a molecular weight of 500 or more 0.005
By weight or more (c) Polyoxyethylene alkylamine 0.005 parts by weight or more (d) Glycerin monofatty acid ester 0.005 parts by weight or more