JPH07206004A - Polyolefine garbage-bag - Google Patents

Abstract

PURPOSE:To provide an polyolefine garbage-bag which is excellent in mechanical strength, translucent, low in calorific value, and inexpensive. CONSTITUTION:A film is made from a resin composition containing: 50-85wt.% resin constituents comprised of (A) 25-80wt.% ethylene. alpha-olefine copolymer having a density of 0.91-0.94g/cm<3> and (B) 2-40wt.% specific low-crystalline olefine copolymer, an amount of constituent (A) >= an amount of constituent (B); and (C) 15-50wt.% calcium carbonate. The film having a thickness of 20-150mum is formed into a bag.

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 semitransparent, and is easily incinerated, that is, has a low calorific value during incineration.

[0002]

2. Description of the Related Art Recently, in local governments, etc., from the viewpoint of resource saving, resource recycling, environmental protection, etc. to separate waste, and to ensure the safety of waste collection workers, the waste bags are Easy incineration and translucency are being promoted rapidly. Conventionally, a black dust bag in which carbon black is added to high-density polyethylene or low-density polyethylene produced by high-pressure radical polymerization has been used. However, since this garbage bag is black and the contents of the bag cannot be discriminated, there is not only the problem of frequent injuries due to broken glass of garbage collection workers, but also the high calorific value at the time of incineration and There are problems such as damage and shortening the life of the incinerator.

On the other hand, a garbage bag made of a composition in which calcium carbonate is mixed with a raw material resin is used. This is because the mixed calcium carbonate suppresses the amount of heat generated per unit weight, and at the same time, 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 obtained by blending calcium carbonate with the above-mentioned 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, tear strength, stretchability, etc. are not sufficient. In addition, the mechanical strength is extremely low and the cost is high.

[0004]

The object of the present invention is to eliminate these drawbacks of the prior art, have sufficient mechanical strength, be semi-transparent, and confirm the contents of a garbage bag, and It is to provide a polyolefin waste bag that is easily incinerated and is inexpensive.

[0005]

The present invention comprises (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-
Copolymer with unsaturated carboxylic acid alkyl ester or derivative thereof, (B ₃ ) amorphous or low crystalline ethylene
Resin component 50 to 85 comprising α-olefin copolymer
Using a film having a thickness of 20 to 150 μm produced by using a resin composition containing 15% by weight of (C) 15 to 50% by weight of calcium carbonate (however, the amount of the component (A) ≧ the amount of the component (B)). The present invention provides a formed polyolefin waste bag.

The present invention will be described in more detail below. The method for producing the (A) ethylene / α-olefin copolymer used in the present invention is not particularly limited. For example, a Ziegler type catalyst mainly composed of a transition metal such as titanium, a Phillips type catalyst mainly composed of a chromium-based catalyst, Any of Kaminsky type catalysts containing metallocene as a main component can be used. A copolymer using a highly active Ziegler type catalyst is particularly 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 a one-stage or multi-stage polymerization having 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.
Those having 4 to 10 carbon atoms are preferable 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,
It is possible to use two or more of these in combination.

The density of the above components is 0.91 to 0.94 g / cm ³
Is used, preferably 0.91 to 0.93 g / cm ³
Is the range. When the density is less than 0.91 g / cm ³ , the film has a weak rigidity and bag making is difficult. The tensile strength of the film is a 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, sufficient tensile strength as a dust bag and propagation resistance of puncture break hole cannot be obtained, and a bag with a hard texture is obtained.

The melt flow rate of the copolymer (A) (hereinafter abbreviated as "MFR") is in the range of 0.1 to 10 g / 10 min, preferably 0.2 to 6 g / 10 min, more preferably Is 0.3-5 g / 10 minutes. If it is less than 0.1 g / 10 minutes, the fluidity is poor and it causes troubles in molding. If it is more than 10 g / 10 minutes, the strength of the film is so low that bubbles are not stabilized during molding.

The (B) olefin-based copolymer used in the present invention is an ethylene / vinyl ester copolymer or 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, both of which have low crystallinity and high flexibility Is something
It is blended for the purpose of giving the bag a soft texture.

The above-mentioned (B ₁ ) ethylene / vinyl ester copolymer is produced by a high-pressure radical polymerization method and contains ethylene as a main component, vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate and vinyl laurate. , Vinyl stearate, vinyl trifluoroacetate, and other vinyl ester monomers. Among these, ethylene / vinyl acetate copolymer (hereinafter, abbreviated as “EVA”) is particularly preferable. 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 min is preferable.

The copolymer of (B ₂ ) ethylene with an α, β-unsaturated carboxylic acid alkyl ester or its derivative includes ethylene / α, β-unsaturated carboxylic acid alkyl ester copolymers and their metals. Salts, amides, imides and the like can be mentioned, but 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 /
Examples thereof include ethyl methacrylate copolymer, and particularly, ethylene / ethyl acrylate copolymer (hereinafter abbreviated as “EEA”) is used. That is, ethylene 50 to 99.
A copolymer composed of 5% by weight of ethyl acrylate and 0.5 to 50% by weight and having an MFR of 0.1 to 50 g / 10 min is preferable.

The (B ₃ ) amorphous or low crystalline ethylene / α-olefin copolymer used in the present invention means amorphous ethylene / propylene rubber (EPR) or ethylene / propylene / cyclopentadiene / ethylidenenor. Ethylene / propylene consisting of diene such as bornun
Examples thereof include diene copolymer rubber (EPDM) and low crystalline ethylene / 1-butene copolymer (EBC).

The component (C) of the present invention, calcium carbonate, may be so-called heavy calcium carbonate obtained by mechanically crushing limestone, or so-called precipitated calcium carbonate obtained by a carbon dioxide gas compounding method. However, it is necessary that the average particle size obtained from the specific surface area is 4 μm or less. If calcium carbonate having an average particle size of more than 4 μm is used, a composition having excellent 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, but in order to further improve the dispersibility of calcium carbonate in the composition (thus also improving impact resistance etc.) and enhancing the moldability, The surface of calcium carbonate is a fatty acid such as stearic acid or oleic acid or its derivative,
Alternatively, it is preferably coated 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 with respect to calcium carbonate. If it is less than 0.2% by weight, the dispersibility or processability may not be improved in some cases, and even if a surface treatment agent in excess of 2% by weight is used, it is usually not economical to expect further improvement in properties.

In the present invention, the sum of the amounts of both components (A) and (B) is 50 to 85% by weight of the total 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. When the amount of the component (A) is less than the amount of the component (B), the film is soft and the bag has a weak stiffness, which makes it 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. Calcium carbonate, which is the component (C) of the present invention, is said to reduce the amount of heat generated during incineration and to capture chlorine gas generated in the incinerator to suppress the generation of dioxin gas and the like. The blending amount of this component is 15 to 50% by weight in the resin composition.
If it is less than 15% by weight, the effect of suppressing the amount of heat generated at the time of incineration is insufficient, and if it exceeds 50% by weight, the mechanical strength of the film becomes low, and at the same time, it becomes semitransparent and the inside cannot be seen.

When the film used in the present invention is molded, it is usually carried out after kneading calcium carbonate and a resin with an extruder. However, this method requires a high cost. Therefore, a method is used in which a master batch having a high concentration of calcium carbonate is prepared in advance, and the master batch is mixed with a resin to be molded. The concentration of calcium carbonate in the masterbatch is 50 to 90% by weight. If it is less than 50% by weight, the dilution ratio at the time of film formation is low, and the advantages of the masterbatch method cannot be obtained. On the other hand, if it exceeds 90% by weight, the dispersion of calcium carbonate becomes insufficient, clogging occurs on the screen of the extruder during the preparation of the masterbatch, and the formed film becomes non-uniform.

The resin for the masterbatch includes (A)
An ethylene / α-olefin copolymer or an olefin-based copolymer having low crystallinity (B) can be used, but when the copolymer (B) is used, a large amount of calcium carbonate can be dispersed, The dispersion state is also favorable, which is preferable. At the same time, it becomes possible to impart a soft texture as a dust bag as described above.

To produce a masterbatch, pellets of the copolymer (A) or (B) and a predetermined amount of calcium carbonate powder are used together with a suitable antioxidant, if necessary, in a Henschel mixer, a V blender. After mixing with a ribbon mixer, a tumbler mixer, etc., the mixture is melted and kneaded using an appropriate kneading machine such as a single-screw extruder, a multi-screw extruder, a Banbury mixer, a kneader.

To form the dust bag, first, pellets obtained by kneading the pellets of the copolymers (A) and (B) and a predetermined amount of calcium carbonate powder with an extruder are used, or
Alternatively, preferably, pellets of the copolymers (A) and (B) and the calcium carbonate masterbatch produced by the above method are used, and if necessary, a stabilizer such as an antioxidant is added, and a Henschel mixer is used. , 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. A trash bag is manufactured from the obtained film by a bag-making machine.

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

The tensile strength of the dust bag obtained as described above is 250 kg / cm ² or more in the longitudinal direction (MD) and the transverse direction (C) in the measurement according to the test method of JIS K-6781.
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. may be added, if necessary, within a range that does not essentially impair the characteristics of the invention. Known additives can be added. In addition, repellents for animals and the like, deodorants and fragrances, etc., can be mentioned as the additives specific to the garbage bag. Since the garbage bag is left outdoors with garbage in it before being collected, the above additives are added to prevent it from being broken by cats and birds and to prevent the odor of the contents from being emitted to the outside. It is used after being coated, coated or impregnated. When adding these, they may be added as a masterbatch like calcium carbonate or may be added individually. When applied or impregnated, the film or bag is used.

[0024]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention. Used in Examples and Comparative Examples (A),
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 minutes; Nippon Petrochemical Co., Ltd. (A ₂ ) ethylene -1-Hexene copolymer (LLDPE) density = 0.920 g / cm ³ , MFR = 0.8 g / 10 minutes; 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
Min; Product name: Nisseki Lexron V270, Nippon Petrochemical
Ltd. (B ₂₎ an ethylene - ethyl acrylate copolymer (EEA) ethyl acrylate content = 10 wt%, MFR = 3 g / 10
Min; Product 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: Tuffmer A-4090, manufactured by Mitsui Petrochemical Industry Co., Ltd. (C) Component: calcium carbonate Average particle size = 1.7 μm, specific surface area = 13000 cm ² / g, surface-treated with saturated fatty acid Product; Product name: BSK-
5. Dowa Calfine Co., Ltd. In addition, the master batch is resin (A) or (B),
In all cases, 80% by weight of calcium carbonate was kneaded.

<Physical property test method> (1) Density: JIS K6758 (2) MFR: 〃 (3) Tensile strength: 〃 (4) Tensile modulus: 〃 (5) Dirt impact strength: ASTM D1709 compliant (6) Film moldability: Stability of bubbles was visually observed during the molding of the inflation film, and the variation in the thickness of the film after molding 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 bubbles sometimes change, and the film thickness also varies to some extent. X: The shape and size of the bubble change, and the film thickness also changes greatly. (7) Texture of film: The trash bag was grasped by the palm and the feeling when the bag was swayed in an empty state was evaluated according to the following criteria. ◯: The feeling of being held by the palm is flexible, and no noise of rubbing the film is generated even when swung. Δ: The feeling of being held by the palm is rather firm, and a sound of rubbing of the film is generated when swung. X: The feeling of being held by the palm is stiff, and when swung around, the unpleasant sound of the film rubbing is generated.

Example 1 LLDPE (A ₁ ) 50%, low crystalline ethylene / α-olefin random copolymer (Toughmer) (B ₃ ) 20% by weight and calcium carbonate (C)
After mixing 30% by weight with a tumbler mixer, an extrusion temperature of 200 ° C (cylinder temperature of 200 ° C, die temperature of 2 with a twin-screw extruder of the same direction with a screw diameter of 65 mmφ and L / D = 30).
The mixture was melt-mixed at 00 ° C. and passed through a pelletizer to prepare pellets. Using the composition thus obtained as a raw material, an inflation film molding machine equipped with a single screw extruder having a screw diameter of 50 mmφ and L / D = 30 was used, and an extrusion temperature of 200 ° C. (cylinder temperature of 200 ° C., die temperature of 20
0 ° C), thickness 3 depending on the molding conditions of blow-up ratio 3.0
A 0 μm film was molded. The bottom of a material made of this film with a folding diameter of 450 mm and a length of 500 mm is
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 blended composition. Moldability, mechanical strength, waist strength, soft 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 carried out using 30% by weight of calcium carbonate (C). I went. The test results are also shown in Table 1 and Table 2. Formability,
The mechanical strength, the strength of the waist, the softness of the texture, the amount of heat generated during combustion, etc. all show satisfactory results.

Example 7 A masterbatch comprising 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 ).
₁ ) 7% by weight and 30% by weight of calcium carbonate (C) were blended to prepare a composition, and the same treatment as in Example 1 was performed. The compounding composition and the test results are shown in Table 2. Moldability, mechanical strength, waist strength, soft texture, calorific value during combustion, etc. all show satisfactory results.

Example 8 LLDPE (A ₁ ) and EVA (B ₁ ) were added to a masterbatch consisting of 80% by weight of calcium carbonate (C) and LLDPE (A ₁ ) to give a final composition of LLDPE (A ₁ ). 63% by weight, EVA (B ₁ ) 7% by weight
Then, calcium carbonate (C) was added in an amount of 30% by weight to prepare a composition, and the same treatment as in Example 1 was performed. The compounding composition and the test results are shown in Table 2. Moldability, mechanical strength, waist strength, soft 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 carried out 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). The results are shown in Table 3. 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. The results are shown in Table 3. The dirt impact strength is low and the texture is bad.

Comparative Example 3 The same treatment as in Example 1 was carried out with a composition of LLDPE (A ₁ ) 40% by weight, Tuffmer (B ₃ ) 5% by weight and calcium carbonate (C) 55% by weight. The results are shown in Table 3. Poor moldability, low dirt impact strength, and poor texture.

Comparative Example 4 The same treatment as in Example 1 was carried out with a composition of 81% by weight of LLDPE (A ₁ ), 9% by weight of Tuffmer (B ₃ ) and 10% by weight of calcium carbonate (C). The results are shown in Table 3. Large heat generation when incinerated.

[0036]

[Table 3]

Comparative Example 5 A film having the same composition as in Example 5 and a thickness of 15 μm was produced, and the same treatment as in Example 1 was performed. The results are shown in Table 4. Dirt impact strength is low and it cannot be used as a dust 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 treatment as in Example 1 was performed. The results are shown in Table 4. The bag is too hard and the texture is inferior.

[0039]

[Table 4]

[0040]

EFFECT OF THE INVENTION The bag of the present invention formed by using the above composition is excellent in mechanical strength, is semitransparent, has a low calorific value, and is inexpensive, and thus is most suitable as a garbage bag.

Claims (2)

[Claims] 1. A material selected from (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 ) to (B ₃ ). 2 to 40% by weight of at least one olefin-based copolymer (B ₁ ) ethylene-vinyl ester copolymer, (B ₂ ) ethylene and α, β-
Copolymer with unsaturated carboxylic acid alkyl ester or derivative thereof, (B ₃ ) amorphous or low crystalline ethylene
Resin component 50 to 85 comprising α-olefin copolymer
Using a film having a thickness of 20 to 150 μm produced by using a resin composition containing 15% by weight of (C) 15 to 50% by weight of calcium carbonate (however, the amount of the component (A) ≧ the amount of the component (B)). A polyolefin garbage bag formed. 2. The resin composition comprises 10 to 50% by weight of (B) an olefin-based copolymer and 50% of (C) calcium carbonate.
The polyolefin waste bag according to claim 1, wherein the polyolefin waste bag is compounded by using a masterbatch of about 90% by weight.