JP3244906B2 - Polyolefin garbage bag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a garbage bag which has high mechanical strength, is translucent, and has easy incineration, that is, has a low calorific value when incinerated.

[0002]

2. Description of the Related Art In recent years, local governments and the like have garbage bags due to problems such as resource separation, resource recycling, separation of garbage from the viewpoint of environmental protection, and security of garbage collection workers. Easier incineration and translucency are being rapidly promoted. Conventionally, a black garbage bag in which carbon black is added to high-density polyethylene or low-density polyethylene obtained by a high-pressure radical polymerization method has been used. However, this garbage bag is black and the contents of the bag cannot be determined, so not only is there a problem that garbage collection workers frequently become injured due to broken glass, etc., and the calorific value during incineration is high. There are problems such as damage and shortening the life of the incinerator.

On the other hand, a garbage bag made of a composition obtained by mixing calcium carbonate with a raw material resin is used. This is because the calorific value per unit weight is suppressed by the mixed calcium carbonate, and the calcium carbonate has an effect of reacting and absorbing halogen which is a toxic gas in the combustion gas. A garbage bag made of a film in which calcium carbonate is blended with the high-density polyethylene or low-density polyethylene produced by a high-pressure radical polymerization method has also been proposed, but since a large amount of calcium carbonate is blended, the tear strength and stretchability are sufficient. In addition, the mechanical strength is extremely low and the cost is high.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate these conventional disadvantages, to have sufficient mechanical strength, to be translucent and to be able to confirm the contents of a garbage bag, and An object of the present invention is to provide a polyolefin garbage bag that is easily incinerated and inexpensive.

[0005]

According to the present invention, there are provided (A) 25 to 80% by weight of an ethylene / α-olefin copolymer having a density of 0.91 to 0.94 g / cm ³ and (B) the following (B ₁ ) from (B ₃₎ at least one olefin-based copolymer 2 to 40 wt% selected from (B ₁₎ an ethylene-vinyl ester copolymer, (B ₂₎ ethylene and alpha, beta-
Copolymers with unsaturated carboxylic acid alkyl esters or derivatives thereof, (B ₃ ) non-crystalline or low-crystalline ethylene
α-olefin copolymer, a resin component comprising 50 to 85
% By weight (however, the amount of the component (A) ≧ the amount of the (B) component) and (C) a film having a thickness of 20 to 150 μm manufactured using a resin composition containing 15 to 50% by weight of calcium carbonate. An object of the present invention is to provide a formed polyolefin garbage bag.

Hereinafter, the present invention will be described in more detail. The method for producing the ethylene / α-olefin copolymer (A) used in the present invention is not particularly limited, and examples thereof include a Ziegler catalyst mainly composed of a transition metal such as titanium, a Phillips catalyst mainly composed of a chromium catalyst, Any of Kaminski type catalysts mainly composed of metallocene or the like can be used. Particularly, a copolymer using a highly active Ziegler-type catalyst is preferable. The polymerization method may be any of a solution method, a slurry method, a gas phase method, and a high-pressure ionic polymerization method, and one obtained by polymerizing in one stage or two or more stages can be used.

(A) The α-olefin which is a component of the ethylene / α-olefin copolymer has 3 to 18 carbon atoms.
And those having 4 to 10 carbon atoms are particularly desirable from the viewpoint of mechanical properties. Specifically, 1-butene, 1-
Pentene, 1-hexene, 4-methyl-1-pentene,
1-octene, 1-nonene, 1-decene and the like,
Two or more of these may be used in combination.

The density of the above components is 0.91 to 0.94 g / cm ³
And preferably 0.91 to 0.93 g / cm ³
Range. If the density is less than 0.91 g / cm ³ , the film has a weak stiffness and it is difficult to make a bag. Tensile modulus is the measure of the stiffness of the film. On the other hand, the density is 0.94g
If it is higher than / cm ³ , mechanical strength such as dirt impact strength and tensile strength is weak, and sufficient tensile strength as a garbage bag and propagation resistance of a puncture break hole cannot be obtained, and the bag has a hard texture.

The copolymer (A) has a melt flow rate (hereinafter abbreviated as "MFR") in the range of 0.1 to 10 g / 10 minutes, preferably 0.2 to 6 g / 10 minutes, more preferably. Is from 0.3 to 5 g / 10 minutes. If it is less than 0.1 g / 10 minutes, the fluidity is poor and the molding is hindered. If it is more than 10 g / 10 minutes, problems such as low film strength and unstable bubbles during molding occur.

The olefin copolymer (B) used in the present invention is an ethylene / vinyl ester copolymer,
α, β-unsaturated carboxylic acid alkyl ester copolymer or amorphous ethylene / α-olefin copolymer rubber or ethylene / propylene-diene copolymer rubber, each having low crystallinity and rich in flexibility Things,
It is blended for the purpose of giving a soft texture to the bag.

The above-mentioned (B ₁ ) ethylene / vinyl ester copolymer is produced by a high-pressure radical polymerization method, comprising ethylene as a main component, vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate and vinyl laurate. And vinyl ester monomers such as vinyl stearate and vinyl trifluoroacetate. Of these, particularly preferred is an ethylene / vinyl acetate copolymer (hereinafter abbreviated as “EVA”). That is, 50 to 99.5% by weight of ethylene and 0.1% of vinyl acetate.
A copolymer consisting of 5 to 50% by weight and having an MFR of 0.1 to 50 g / 10 minutes is preferred.

(B ₂ ) As the copolymer of ethylene and an α, β-unsaturated carboxylic acid alkyl ester or a derivative thereof, ethylene / α, β-unsaturated carboxylic acid alkyl ester copolymers and their metal Salts, amides, imides and the like can be mentioned, and these are preferably produced by a high-pressure radical polymerization method. Specifically, ethylene / methyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methyl acrylate copolymer
Ethyl methacrylate copolymer and the like are mentioned, and in particular, ethylene / ethyl acrylate copolymer (hereinafter, abbreviated as “EEA”) is used. That is, ethylene 50-99.
A copolymer comprising 5% by weight and 0.5 to 50% by weight of acrylic acid ethyl ester and having an MFR of 0.1 to 50 g / 10 minutes is preferred.

The (B ₃ ) non-crystalline or low-crystalline ethylene / α-olefin copolymer used in the present invention includes amorphous ethylene / propylene rubber (EPR), ethylene and propylene, cyclopentadiene, ethylidene nor Ethylene / propylene composed of diene such as bornnene
Diene copolymer rubber (EPDM); and low crystalline ethylene / 1-butene copolymer (EBC).

The calcium carbonate as the component (C) of the present invention may be so-called heavy calcium carbonate obtained by mechanically pulverizing limestone, or so-called precipitated calcium carbonate obtained by a carbon dioxide compounding method. However, the average particle size determined from the specific surface area needs to be 4 μm or less. If calcium carbonate having an average particle size exceeding 4 μm is used, a composition excellent in impact resistance cannot be obtained. The average particle size is preferably 3 μm or less.

In the present invention, calcium carbonate may be used as it is. However, in order to further improve the dispersibility of the calcium carbonate in the composition (therefore, the impact resistance and the like are also improved) and to improve the moldability, Fatty acids such as stearic acid and oleic acid or derivatives thereof on the surface of calcium carbonate,
Alternatively, it is preferable to coat with a surface treatment agent such as paraffin, wax, organic silane, organic titanate, and epoxy resin. The amount of the surface treatment agent is preferably about 0.2 to 2% by weight based on calcium carbonate. If the amount is less than 0.2% by weight, the dispersibility or the processability may not be improved, and even if the surface treatment agent exceeds 2% by weight, it is usually not economical to expect further improvement of the properties and it is not economical.

The sum of the amounts of both components (A) and (B) in the present invention is 50 to 85% by weight of the whole resin composition. The amount of the component (A) ≧ the amount of the component (B), and the amount of the component (A) in the resin composition is 25 to 80% by weight;
The amount of the component (B) needs to be 2 to 40% by weight. If the amount of the component (A) is smaller than the amount of the component (B), the film is soft and the bag is stiff and difficult to handle. However, when the amount of the component (B) is less than 2% by weight, the dart impact strength is low, the bag is hard and the texture is poor. It is said that calcium carbonate, which is the component (C) of the present invention, reduces the amount of heat generated during incineration, and suppresses the generation of dioxin gas and the like by capturing chlorine gas generated in the incinerator. The compounding amount of this component is 15 to 50% by weight in the resin composition.
If the amount is less than 15% by weight, the effect of suppressing the amount of heat generated during incineration is insufficient. If the amount exceeds 50% by weight, the film becomes inferior in mechanical strength, and at the same time, is not translucent and the inside becomes invisible.

When forming the film used in the present invention, usually, the calcium carbonate and the resin are kneaded by an extruder and then formed. However, since this method increases the cost, a method is used in which a masterbatch having a high calcium carbonate concentration is prepared in advance and mixed with a resin to mold. The concentration of calcium carbonate in the masterbatch is 50-90% by weight. If it is less than 50% by weight, the dilution ratio at the time of film formation is low, and the advantage of the master batch method cannot be obtained. On the other hand, if it exceeds 90% by weight, the dispersion of calcium carbonate becomes insufficient, so that clogging occurs on the screen of the extruder during production of the master batch, and the formed film becomes non-uniform.

As the resin for the master batch, (A)
Ethylene / α-olefin copolymer or low crystalline (B) olefin copolymer can be used, but using copolymer (B) makes it possible to disperse a large amount of calcium carbonate, This is preferable because the state of dispersion is improved. At the same time, it becomes possible to give a soft texture as a garbage bag as described above.

To prepare a masterbatch, a pellet of the copolymer (A) or (B) and a predetermined amount of calcium carbonate powder are added together with a suitable antioxidant, if necessary, to a Henschel mixer, a V blender. After mixing with a ribbon mixer, tumbler mixer, etc., the mixture is melt-kneaded using a suitable kneader, for example, a single screw extruder, a multi-screw extruder, a Banbury mixer, a kneader, or the like.

To form a garbage bag, first, pellets obtained by kneading pellets of the copolymers (A) and (B) and a predetermined amount of calcium carbonate powder with an extruder are used.
Alternatively, preferably, the pellets of the copolymers (A) and (B) and the master batch of calcium carbonate produced by the above-mentioned method are used, and if necessary, a stabilizer such as an antioxidant is added. , V blender, ribbon mixer, tumbler mixer and the like, and then formed into a film having a thickness of 20 to 150 μm by inflation molding or T-die molding. From the obtained film, a garbage bag is manufactured by a bag making machine.

Although the thickness of the garbage bag varies depending on the application, 20 to 80 μm is generally used for household garbage bags, and 50 to 150 μm is used for other large garbage bags. If the thickness is less than 20 μm, the strength is low because the thickness is too thin, the tensile strength is insufficient, and the film is easily torn. On the contrary, if the thickness exceeds 150 μm, the bag becomes too hard to handle, which is not preferable.

The tensile strength of the garbage bag obtained as described above, as measured by the test method of JIS K-6781, is 250 kg / cm ² or more in the machine direction (MD) and the transverse direction (C
D) shows a value of 150 kg / cm ² or more.

In the present invention, an antistatic agent, an antioxidant, a lubricant, an antifogging agent, an organic or inorganic pigment, an ultraviolet absorber, a dispersant, etc., if necessary, as long as the characteristics of the invention are not essentially impaired. Known additives can be added. In addition, as an additive peculiar to a garbage bag, a repellent for animals and the like, a deodorant / deodorant, a fragrance, and the like can be given. The garbage bag is left outdoors with garbage in it before being collected, so the above additives are added to avoid being broken by cats and birds and to prevent the odor of the contents from being emitted outside. It is used after being coated or impregnated or impregnated. When these are added, they may be made into a masterbatch similarly to calcium carbonate, or may be added individually. When applying or impregnating, it is performed in the form of a film or a bag.

[0024]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. (A) used in Examples and Comparative Examples,
The components (B) and (C) are shown below. Component (A): (A ₁ ) ethylene / 1-butene copolymer (LLDPE) Density = 0.920 g / cm ³ , MFR = 0.8 g / 10 min; (A ₂ ) ethylene manufactured by Nippon Petrochemical Co., Ltd. 1-Hexene copolymer (LLDPE) Density = 0.920 g / cm ³ , MFR = 0.8 g / 10 min; Nippon Petrochemical Co., Ltd. (B) component (low crystalline olefin copolymer): (B ₁ ) Ethylene-vinyl acetate copolymer (EVA) Vinyl acetate content = 15% by weight, MFR = 1.5 g / 10
Minute; Trade name: Nisseki Lexlon V270, Nippon Petrochemical
Ltd. (B ₂₎ an ethylene - ethyl acrylate copolymer (EEA) ethyl acrylate content = 10 wt%, MFR = 3 g / 10
Min; Trade name: Nisseki Lexlon A3100, Nippon Petrochemical
(B ₃ ) Low crystalline ethylene / 1-butene copolymer (EB
C) Density = 0.890 g / cm ³ , MFR = 3.6 g / 10 min, Tm = 7
6 ° C .; trade name: Toughmer A-4090, manufactured by Mitsui Petrochemical Industries, Ltd. (C) component: calcium carbonate Average particle size = 1.7 μm, specific surface area = 13000 cm ² / g, surface treated with saturated fatty acid Thing; trade name: BSK-
5. Dowa Calfine Co., Ltd. The master batch is applied to resin (A) or (B).
In each case, calcium carbonate kneaded at 80% by weight was used.

<Physical property test method> (1) Density: JIS K6758 compliant (2) MFR: 〃 (3) Tensile strength: 〃 (4) Tensile modulus: 〃 (5) Dart impact strength: compliant with ASTM D1709 (6) Film formability: During the formation of the blown film, the stability of the bubbles was visually observed, and the variation in the thickness of the film after the formation was measured and judged. The evaluation criteria are as follows. ：: The bubble shape and size are stable and the film thickness is uniform. Δ: The shape and size of the bubble sometimes changed, and the film thickness also slightly varied. X: The shape and size of the bubble change, and the film thickness also changes greatly. (7) Texture of the film: The garbage bag was grasped with the palm, and the feeling when the bag was swung in an empty state was evaluated according to the following criteria. ：: The feeling of holding the film with the palm is flexible, and the sound of rubbing of the film does not occur even when the film is swung. Δ: The feeling of gripping with the palm was slightly hard, and a sound of rubbing of the film was generated when shaken. ×: The feeling of gripping with the palm was rough, and when shaken, an unpleasant sound of rubbing the film was generated.

<Example 1> 50% of LLDPE (A ₁ ), 20% by weight of low-crystalline ethylene / α-olefin random copolymer (tuffmer) (B ₃ ) and calcium carbonate (C)
After mixing 30% by weight with a tumbler mixer, the extruding temperature was 200 ° C. (cylinder temperature 200 ° C., die temperature 2
(00 ° C.) and pelletized through a pelletizer. Using the composition thus obtained as a raw material, an extrusion temperature of 200 ° C. (cylinder temperature 200 ° C., die temperature 20 ° C.)
0 ° C) and a blow-up ratio of 3.0
A 0 μm film was formed. The bottom of a 450 mm long, 500 mm long material made of this film
A bag was formed by heat sealing at ℃. Table 1 shows the results of various tests performed on the film and the bag together with the composition. Formability, mechanical strength, stiffness, softness of texture, calorific value during combustion, etc. all show satisfactory results.

<Examples 2 to 6> LLDPE (A ₁ ), LL
DPE (A ₂ ), EVA (B ₁ ) and EEA (B ₂ ) were blended in the compositions shown in Tables 1 and 2, and the same treatment as in Example 1 was performed using 30% by weight of calcium carbonate (C). Was done. The test results are also shown in Tables 1 and 2. Moldability,
The mechanical strength, the waist strength, the softness of the texture, and the calorific value during combustion all show satisfactory results.

Example 7 A master batch composed of 80% by weight of calcium carbonate (C) and EVA (B ₁ ) was used, and the final composition was 63% by weight of LLDPE (A ₁ ) and EVA (B
₁ ) A composition was prepared by mixing 7% by weight and 30% by weight of calcium carbonate (C), and the same treatment as in Example 1 was performed. Table 2 shows the composition and the test results. Formability, mechanical strength, stiffness, softness of texture, calorific value during combustion, etc. all show satisfactory results.

Example 8 LLDPE (A ₁ ) and EVA (B ₁ ) were added to a master batch composed of 80% by weight of calcium carbonate (C) and LLDPE (A ₁ ), and the final composition was LLDPE (A ₁ ). 63% by weight, EVA (B ₁ ) 7% by weight
A composition was prepared by blending with calcium carbonate (C) at 30% by weight, and the same treatment as in Example 1 was performed. Table 2 shows the composition and the test results. Formability, mechanical strength, stiffness, softness of texture, calorific value during combustion, etc. all show satisfactory results.

[0030]

[Table 1]

[0031]

[Table 2]

<Comparative Example 1> The same treatment as in Example 1 was performed with a composition of 28% by weight of LLDPE (A ₁ ), 42% by weight of EVA (B ₁ ) and 30% by weight of calcium carbonate (C). Table 3 shows the results. The waist of the bag is weak.

Comparative Example 2 69% by weight of LLDPE (A ₁ ), ₁ % by weight of EEA (B ₂ ) and calcium carbonate (C)
The same treatment as in Example 1 was performed with a composition of 30% by weight. Table 3 shows the results. Low dart impact strength and poor texture.

Comparative Example 3 The same treatment as in Example 1 was performed with a composition of 40% by weight of LLDPE (A ₁ ), 5% by weight of tufmer (B ₃ ) and 55% by weight of calcium carbonate (C). Table 3 shows the results. Poor moldability, low dart impact strength, poor texture.

<Comparative Example 4> The same treatment as in Example 1 was performed using a composition of 81% by weight of LLDPE (A ₁ ), 9% by weight of tufmer (B ₃ ) and 10% by weight of calcium carbonate (C). Table 3 shows the results. Large heat value during incineration.

[0036]

[Table 3]

Comparative Example 5 A film having the same composition as in Example 5 and a thickness of 15 μm was prepared, and the same treatment as in Example 1 was performed. Table 4 shows the results. Dirt impact strength is low and cannot be used as a garbage bag.

Comparative Example 6 A film having the same composition as in Example 5 and a thickness of 180 μm was formed, and the same processing as in Example 1 was performed. Table 4 shows the results. The bag is too hard and the texture is poor.

[0039]

[Table 4]

[0040]

The bag of the present invention formed by using the above composition has excellent mechanical strength, is translucent, has a low calorific value, and is inexpensive, so that it is most suitable as a garbage bag.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-122533 (JP, A) JP-A-58-7347 (JP, A) JP-A-7-33152 (JP, A) 22295 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) B65D 30/02 B65F 1/00 C08K 3/26 C08L 23/08

Claims (2)

(57) [Claims] 1. (A) 25 to 80% by weight of an ethylene / α-olefin copolymer having a density of 0.91 to 0.94 g / cm ³ and (B) selected from the following (B ₁ ) to (B ₃ ) 2 to 40% by weight of at least one olefin copolymer (B ₁ ) ethylene / vinyl ester copolymer, (B ₂ ) ethylene and α, β-
Copolymers with unsaturated carboxylic acid alkyl esters or derivatives thereof, (B ₃ ) non-crystalline or low-crystalline ethylene
α-olefin copolymer, a resin component comprising 50 to 85
% By weight (however, the amount of the component (A) ≧ the amount of the (B) component) and (C) a film having a thickness of 20 to 150 μm manufactured using a resin composition containing 15 to 50% by weight of calcium carbonate. A garbage bag made of polyolefin. 2. The resin composition comprises (B) 10 to 50% by weight of an olefin copolymer and (C) 50% of calcium carbonate.
The polyolefin garbage bag according to claim 1, wherein the garbage bag is blended by using a master batch consisting of up to 90% by weight.