JP2567248B2 - Resin composition for film molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a film mainly composed of a linear ethylene copolymer having high strength, high transparency, and improved balance of antiblocking property and slipperiness. The present invention relates to a molding resin composition.

<Prior art> For the polyethylene film used for packaging, low density polyethylene (hereinafter abbreviated as HP-LDPE) produced by a high pressure radical polymerization method and ethylene-vinyl acetate copolymer are conventionally used. It has been. In recent years, linear low-density polyethylene (hereinafter abbreviated as L-LDPE) using Ziegler type catalyst has been developed. This L-LDPE has mechanical strength such as impact strength and low temperature impact strength and heat resistance compared to HP-LDPE. It has excellent properties, stress cracking resistance, heat sealability and hot tack property, and has begun to be used in many fields and has come to be used for packaging materials.

However, the L-LDPE film has a poor balance of physical properties such as transparency, anti-blocking property, slipperiness, and strength. In order to improve this, JP-A-58-191733 and JP-A-59-98147
Various studies have been made on additives in Japanese Patent Laid-Open Publications and the like.

For example, as a stabilizer for thermoplastic resins such as polyolefin, tetrakis [methylene-3 (3 ', 5'
-Di-t-butyl-4-hydroxyphenyl) propionate] methane is well known, but the film produced from the composition to which it is added has poor anti-blocking property.

Octadecyl-3 to improve anti-blocking properties
Addition of-(4'-hydroxy-3,5'-di-t-butylphenyl) propionate has a smaller effect of heat stability than the former, and if it is added alone in a large amount, the end face of the film is colored after aging. Is sometimes observed, which is not preferable.

On the other hand, silica and talc are used as anti-blocking agents, and oleic acid amides, which are unsaturated fatty acid amides used in HP-LDPE, are used as lubricants.
In the case of L-LDPE alone, the effects of these additives are obtained, whereas in the composition blended with HP-LDPE, it is found that the composition has excellent slipperiness, transparency and anti-blocking property. Absent.

As a method for forming a highly transparent film of L-LDPE, a T-die forming method, a water-cooled inflation forming method, and an air-cooled two-stage cooling inflation forming method are known. However, T
-The die molding method has high processing costs, and the air-cooled two-stage cooling inflation molding method has poor operation, resulting in reduced work efficiency.
Therefore, it is desirable that the processing cost is low and a highly transparent film can be easily obtained by a general-purpose air-cooled inflation film forming method. It is known to blend HP-LDPE etc. as the method.

However, simply blending L-LDPE with HP-LDPE gives good transparency, but the anti-blocking property and slipperiness are significantly deteriorated, making it completely impractical. In order to improve this, a method of adding an anti-blocking agent such as silica or talc or a lubricant is used. However, in the conventional method, as described above, only anti-blocking properties, slip properties, etc. are inferior and the physical properties are unbalanced.

<Problems to be Solved by the Invention> In view of the present situation, the conventional drawbacks, that is, L-LDPE and HP-
An object of the present invention is to obtain a film-forming resin composition which has a good balance of physical properties such as tensile strength, impact strength, anti-blocking property, and slip when LDPE is blended, and has high transparency and is free from coloration over time.

<Means for Solving the Problem> That is, the present invention provides (I) a copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms, which is produced using a Ziegler type catalyst, and has a density of 0.910 to 0.940. g / cm ³ Melt flow rate 0.3 to 10 g / 10 min Melt flow rate ratio 40 or less 100 parts by weight of copolymer having a melting point of 110 to 130 ° C (II) Low density polyethylene produced by high pressure radical polymerization method 1 to 40 parts by weight (III) octadecyl-3- (4'-hydroxy-3,5 '
-Di-t-butylphenyl) propionate and phosphite-based heat stabilizer in combination with 0.01-
0.5 parts by weight (IV) Anti-blocking agent 0.05-1.0 parts by weight (V) Organic fatty acid amide 0.05 comprising a combination of unsaturated fatty acid amide having a melting point of 80 ° C. or higher and saturated fatty acid amide
It is a resin composition for film formation, characterized in that it is comprised from 0.5 to 0.5 parts by weight.

The copolymer (I) with ethylene used in the present invention is obtained by polymerizing ethylene and an α-olefin having 3 to 18 carbon atoms using a Ziegler catalyst. The copolymerization reaction is usually carried out at a polymerization temperature of 30 to 300 ° C., a normal pressure to a pressure of 3000 kg / cm ² , a solvent in the presence of a gas-solid, liquid-solid or homogeneous liquid phase.

As the α-olefin, butene-1,4-methylpentene-1, hexene-1, octene-1, decene-1 and the like are used, and those having 4 to 10 carbon atoms are preferable. These α-olefins may be used alone or in combination of two or more.

The ethylene / α-olefin copolymer (I) has a density of 0.
If it is less than 910 g / cm ^{3, the} film will become sticky and the anti-blocking property will not be improved even if the additives described below are added. 0.
If it exceeds 940 g / cm ³ , the rigidity is large, the strength is significantly reduced, and the transparency is deteriorated.

Melt flow rate (hereinafter abbreviated as MFR) is 0.3g / 10
If it is less than 10 minutes, the moldability is inferior, and if it exceeds 10 g / 10 minutes, the melt viscosity is low and film forming is difficult.

Preferably, the density is 0.915 to 0.940 g / cm ³ , MFR 0.5 to ⁷ g / 10
Minutes are good.

If the ethylene / α-olefin copolymer used in the present invention is a copolymer having the above-mentioned properties, an inflation film excellent in mechanical properties such as impact resistance and tensile strength can be obtained, but a melt showing a molecular weight distribution If the flow rate ratio (hereinafter abbreviated as MFRR) exceeds the above range, the impact strength will drop significantly, so it must be 40 or less. Further, those of 35 or less are more preferable because a film excellent in impact strength and transparency can be obtained.

In the present invention, the MFRR is obtained by the following equation, which is the ratio of two MFR values measured according to JIS K7210 Condition 7 and Condition 4.

The melting point of the ethylene / α-olefin copolymer (I) is measured by using a differential scanning calorimeter (DSC), and the sample is held at 180 ° C for 5 minutes, and 5 ° C / minute. After cooling to 50 ° C at a rate, it is the highest temperature among one or more, and in most cases two or three sharp endothermic peaks obtained from the endothermic curve at a temperature rising rate of 5 ° C / min. Melting point
If it is less than 110 ℃, it is inferior in heat resistance and easy to block, and if it exceeds 130 ℃, it is inferior in low temperature heat sealability. The melting point of the copolymer (I) is 110 to 130 ° C, preferably 115 to 125 ° C.

The component (II) used in the present invention is a low density polyethylene produced by a high pressure radical polymerization method, and it is necessary that the amount is 1 to 40 parts by weight based on 100 parts by weight of the copolymer (I). is there. If it is less than 1 part by weight, the transparency cannot be obtained, and if it exceeds 40 parts by weight, the mechanical strength, heat sealing property and hot tack property are deteriorated. The density of low-density polyethylene is 0.915 to 0.935 g / cm in terms of anti-blocking property and rigidity.
³ is preferable. Further, the MFR is preferably 0.1 to 50 g / 10 min in view of transparency, film processability and antiblocking property.

The component (III) used in the present invention is octadecyl-3-
(4'-Hydroxy-3,5'-di-t-butylphenyl) propionate and a phosphite-based heat stabilizer are used in combination, and the addition amount is 0.01 to 0.
It is necessary to add 5 parts by weight. If the addition amount is less than 0.01 parts by weight, the resin composition may be thermally deteriorated during film forming, and if it exceeds 0.5 parts by weight, blocking and coloring problems occur.

The mixing ratio of these two components is preferably in the range of 80:20 to 25:75 (weight ratio), more preferably in the range of 60:40 to 30:70 (weight ratio), from the viewpoint of thermal stability effect and coloration prevention. is there.
If the phosphite compounding ratio is less than the above range, coloring tends to occur, and if it exceeds it, the heat stability is poor.

Preferred examples of the phosphite heat stabilizer include tetrakis 2,4-di-t- (butylphenyl) -4,4'-biphenylene diphosphanite and tris (2,4-di-t).
-Butylphenyl) phosphite and the like.

The component (IV) used in the present invention needs to be added in an amount of 0.05 to 1.0 part by weight. If the addition amount is less than 0.05 parts by weight, the antiblocking property of the film is not improved, and if it exceeds 1.0 parts by weight, the transparency of the film decreases. The average particle size is 0.3μ from the viewpoint of anti-blocking effect and transparency.
A preferable anti-blocking agent having a particle size of ˜8 μm and a particle size of 10 μm or more is 5 vol% or less.

Examples of the anti-blocking agent include aluminosilicate, kaolin, zeolite and silica. These may be natural or synthetic, and one kind or a mixture of two or more kinds may be used.

Here, the average particle size of the anti-blocking agent is a value measured by using a Coulter counter and dispersing the anti-blocking agent in an electrolytic solution for 2 minutes by ultrasonic waves.

The component (V) used in the present invention needs to be added in an amount of 0.05 to 0.5 parts by weight. If the amount added is less than 0.05 parts by weight, the slip property and anti-blocking property will be significantly reduced.
If it exceeds 0.5 parts by weight, not only is it slippery, but also the printability is deteriorated, which is not preferable. The mixing ratio of both components of unsaturated fatty acid amide and saturated fatty acid amide is 95: 5 to 50:50 (weight ratio), and more preferable range is 90:10 to 70:30 (weight ratio). When the compounding ratio of the saturated fatty acid amide is less than 5, blocking is deteriorated, and when it exceeds 50, the bleeding speed becomes slow and the slipperiness is impaired. Unsaturated fatty acid amides include erucic acid amide (melting point: 84 ° C), and saturated fatty acid amides include stearic acid amide (melting point: 103 ° C) and behenic acid amide (melting point: 110).
However, if the melting point of the organic fatty acid amide is 80 ° C or less, the blocking property is significantly deteriorated.

The melting point of organic fatty acid amide is the differential scanning calorimeter (DS
It is the maximum temperature of the endothermic peak obtained from the endothermic curve of temperature rising rate 5 ° C / min of C).

In order to obtain the resin composition for film molding of the present invention, copolymers (I) and (II) and (III), (IV) and (V) of ethylene and an α-olefin having 3 to 18 carbon atoms are used. A known method within the above range with each additive, for example, a method of mixing with a tumbler blender, a Henschel mixer, etc., a method of further melt-kneading and granulating with a single-screw extruder, a multi-screw extruder, etc.
Alternatively, a method of melt-kneading and granulating with a kneader, Banbury mixer or the like can be adopted.

It is also possible to obtain a mixture of the copolymer (I), each of the additives (III), (IV) and (V) melt-kneaded and granulated by the above method and (II) with a tumbler blender or the like. it can.

In the present invention, an antistatic agent, a weatherproofing agent, a UV agent and an antifogging agent which are commonly used may be blended within a range that does not impair the object of the present invention.

The resin composition for molding of the present invention is processed by ordinary air-cooling inflation molding, air-cooling two-stage cooling inflation molding, T-die film molding, water-cooling inflation molding, etc. to form a film excellent in transparency and antiblocking property. Obtainable.

The resin composition film for film molding of the present invention is L-LD
As PE has excellent impact strength, tear strength, transparency, heat sealability, hot tack, heat resistance, etc., it is a standard bag, sugar bag, oil packaging bag, water packaging bag, etc. It is suitable for various packaging films, agricultural materials, etc. Also,
A film made of a resin composition for film formation and a base material such as nylon or polyester may be bonded together to be used as a multilayer film.

<Examples> Examples-1 to 11 and Comparative Examples 1 to 10 The formulations of the compositions are shown in Tables 1 and 2, and the results are shown in Table 3.

 The experiment was conducted as follows for each composition.

1) Film processing Film processing method (1) L-LDPE using a composition with a single slit air ring
Air-cooled inflation extruder (40mm diameter, screw L /
D = 18) and spiral die 125mm diameter (lip opening, 2m
film thickness at a blue ratio of 1.8 and a processing temperature of 200 ° C.
Extruded to 30μ.

Film processing method (2) Processing was carried out at a processing temperature of 170 ° C in the same manner as the air-cooled inflation.

2) Physical property measurement (1) Haze value (Haze) Measured according to ASTM D1003.

(2) Narrow angle scattering index (NAS) After conditioning the molded film at 23 ° C ± 1 ° C, 50 ± 10% RH for 24 hours or more, the narrow angle scattering index is measured with a narrow angle scattering index measuring instrument manufactured by Toyo Seiki Seisakusho. taking measurement.

There is a sense of see-through with this film, and in a broad sense it is a measure of the quality of transparency. The smaller this value is, the more preferable.

(3) Blocking The molded film was accelerated at room temperature (23 ° C) under a load of 30 g / cm ² for 12 hours, after which the test piece cut into 22 cm × 10 cm was fixed to a jig so that the adhesive surface would be 10 cm 10 cm. Then
Peeling load The load (g / 100 cm) required to peel off the entire film when moved at a moving speed of 20 g / min.

This value is a measure of the degree of openness of the film. The smaller the value, the better. However, if it exceeds 25 g / 100 cm ² , a serious defect occurs.

(4) Film impact strength The Dart Impact of the film was measured according to ASTM D1709.

(5) Yellowness (YI) A sheet having a thickness of 2 mm was prepared and aged for 2 weeks under the conditions of 60 ° C. and 90% RH, and the yellowness (YI) was measured (based on ASTM D7103). This value is a measure of the degree of color change of the film over time, and those with a value of 15 or less are (○), and those with a value of 15 or more are (X). The film evaluated as (x) has a lower commercial value in terms of coloring over time.

<Effects of the Invention> The resin composition film for film molding of the present invention is excellent in transparency and has a good balance of anti-blocking property, strength, slip property and the like.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 23:06)

Claims (5)

(57) [Claims] (I) A copolymer of ethylene and an α-olefin having 3 to 18 carbon atoms, which is produced using a Ziegler type catalyst, and has a density of 0.910 to 0.940 g / cm ^{3 and a} melt flow rate of 0.3 to 10g / 10min Melt flow rate ratio 40 or less Melting point Copolymer having a value of 110 to 130 ° C 100 parts by weight (II) Low density polyethylene produced by high pressure radical polymerization method 1 to 40 parts by weight (III) Octadecyl-3 -(4'-hydroxy-3,5 '
-Di-t-butylphenyl) propionate and a phosphite-based heat stabilizer in combination 0.01 to 0.
5 parts by weight (IV) Anti-blocking agent 0.05 to 1.0 parts by weight (V) Organic fatty acid amide consisting of a combination system of unsaturated fatty acid amide having a melting point of 80 ° C. or higher and saturated fatty acid amide.
A resin composition for film molding, which comprises from 05 to 0.5 parts by weight. 2. The film-forming resin according to claim 1, wherein the polyethylene produced by the high-pressure radical polymerization method has a density of 0.915 to 0.935 g / cm ³ and a melt flow rate of 0.1 to 50 g / 10 minutes. Composition. 3. Octadecyl-3- (4'-hydroxy-)
The compounding ratio of 3,5′-di-t-butylphenyl) propionate and phosphite heat stabilizer is 80:20 to 25:75.
The resin composition for film molding according to claim 1, which is (weight ratio). 4. The anti-blocking agent has an average particle size of 0.3 to 8 μm.
The resin composition for film molding according to claim 1, wherein the resin having a particle size of 10 μ or more is 5 vol% or less. 5. The resin composition for film formation according to claim 1, wherein the blending amount of the unsaturated fatty acid amide having a melting point of 80 ° C. or higher and the saturated fatty acid amide is 95: 5 to 50:50.