JP3244907B2 - Easy incineration trash 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. For example, a blend resin composition in which calcium carbonate is blended with the high-density polyethylene or the low-density polyethylene alone by the high-pressure radical polymerization method, or a mixture of the high-density polyethylene and the linear low-density polyethylene, has been proposed. It has also been suggested that the use of
No. 22295). However, this composition has a small amount of linear low-density polyethylene and a large amount of calcium carbonate, so that the tear strength and stretchability are not sufficient, the mechanical strength is extremely low, and the cost is low. Is not high enough to achieve the objective.

[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 It is an object of the present invention to provide a cheap garbage bag that is easily incinerated and has a good texture.

[0005]

According to the present invention, (A) 25-80% by weight of polyethylene having a density of 0.94 g / cm ³ or more and (B) selected from the following (B ₁ ) and (B ₃ ). at least one ethylene copolymer from 2 to 40 wt% (B ₁₎ density 0.8
6 g / cm ³ or more and 0.91 g / cm less than ^3, the melting point 100 ° C.
Ethylene-α-olefin copolymer having a boiling n-hexane insoluble content of 10% by weight or more, (B ₂ )
50-85% by weight of a resin component comprising a vinyl ester copolymer and (B ₃ ) an ethylene-α, β-unsaturated carboxylic acid alkyl ester copolymer (provided that the amount of the component (A) ≧
(B) The amount of the component (B) and (C) 15 to 50% by weight of calcium carbonate.

Hereinafter, the contents of the present invention will be described in detail. The polyethylene having a density of 0.94 g / cm ³ or more, which is the component (A) used in the present invention, refers to a polymer of ethylene alone, a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, and a copolymer thereof. And specific examples of the α-olefin include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-dodecene, and the like. Particularly preferred among these α-olefins are propylene and 1-butene. Its density is in the range of ^{0.94g / cm 3 ~0.98g / cm 3} , a melt flow rate (hereinafter abbreviated as "MFR") of 0.0
It is selected from the range of 1 to 10 g / 10 min, preferably 0.02 to 2 g / 10 min, and more preferably 0.03 to 0.5 g / 10 min. The method for producing the component (A) is not particularly limited. It may be produced by one-stage polymerization or by two or more stages of multi-stage polymerization. In any of the above cases, the reaction mode is not particularly limited, and various methods such as a slurry method, a gas phase method, and a solution method can be used. The polymerization catalyst is also not particularly limited, and for example, any of a Ziegler type catalyst, a Phillips type catalyst, a Kaminsky type catalyst and the like can be used.

The component (B) in the present invention includes:
(B ₁₎ density of 0.86 g / cm ³ or more and 0.91 g / cm less than ^3, a melting point of 100 ° C. or higher, the boiling n- hexane insoluble fraction 1
0% by weight or more of ethylene / α-olefin copolymer,
(B ₂₎ an ethylene - vinyl ester copolymer, and (B ₃₎
At least one ethylene copolymer selected from ethylene-α, β-unsaturated carboxylic acid alkyl ester copolymers is exemplified.

[0008] The above (B ₁₎ density of 0.86 g / cm ³ or more and less than 0.91 g / cm ^3, a melting point of 100 ° C. or higher, the boiling n
Examples of the ethylene / α-olefin copolymer having a hexane-insoluble content of 10% by weight or more include a high / medium / low pressure method using a Ziegler catalyst or the like and other known methods (for example, JP-A-55-56110, JP-A-55-56111) discloses an ultra-low-density polyethylene (hereinafter, referred to as “VLDPE”) obtained by copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms. Specific α
-As olefins, propylene, 1-butene, 4-
Methyl-1-pentene, 1-hexene, 1-octene, 1-dodecene and the like can be mentioned. Of these, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene are preferred, and 1-butene is particularly preferred. The α-olefin content in the ethylene copolymer is preferably 5 to 40 mol%.

[0009] The VLDPE has a density of 0.86 g / cm ³ or more and less than 0.91 g / cm ^3, differential scanning calorimetry (DSC) melting point of 100 ° C. or higher by, preferably 11
0 ° C. or more, more preferably 116 ° C. or more, and boiling n
A hexane-insoluble component having a property of 10% by weight or more, preferably 20% by weight or more;
LDPE) and an ethylene / α-olefin copolymer rubber. More specifically, a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, the resin having both a high crystalline portion represented by LLDPE and an amorphous portion represented by an ethylene / α-olefin copolymer rubber The former feature of mechanical strength, heat resistance and the like, and the latter feature of self-adhesiveness, rubbery elasticity, low-temperature impact resistance and the like coexist in a well-balanced manner. Useful. VLDPE above
Is produced using a catalyst system in which an organoaluminum compound is combined with a solid catalyst component containing at least magnesium and titanium, and is produced using a vanadium catalyst, and has an melting point of less than 100 ° C. They are distinctly different from copolymers. VLDPE
There is no particular limitation on the type of reaction for producing, and various methods such as a slurry method, a gas phase method, and a solution method can be used. The production method may be one-stage polymerization or two-stage or more multi-stage polymerization.

The above-mentioned (B ₂ ) ethylene-vinyl ester copolymer is prepared 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, and other unsaturated monomers. Of these, particularly preferred are ethylene-vinyl acetate copolymers. That is, 50 to 99.5% by weight of ethylene and 0.1% of vinyl acetate.
5-50% by weight and 0-25% by weight of other unsaturated monomers
Is preferred.

The above (B ₃ ) ethylene-α, β-unsaturated carboxylic acid alkyl ester copolymer includes copolymers of ethylene with α, β-unsaturated carboxylic acid alkyl ester and other unsaturated monomers. Examples thereof include coalesce, and metal salts, amides, and imides thereof, and preferably include an ethylene-ethyl acrylate copolymer produced by a high-pressure radical polymerization method. That is, ethylene 50
９９99.5% by weight, acrylic acid ethyl ester 0.5-5
Copolymers consisting of 0% by weight and 0 to 25% by weight of other unsaturated monomers are preferred. The alkyl group of the alkyl ester is selected from the range of 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms.

Other unsaturated monomers used in the copolymers (B ₂ ) and (B ₃ ) include propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1,
Olefins having 3 to 10 carbon atoms, such as decene -1, C ₂ ~
Vinyl esters of C ₃ alkanecarboxylic acids, acrylic or methyl methacrylate, acrylic or ethyl methacrylate, acrylic or propyl methacrylate, acrylic or methacrylic esters such as glycidyl acrylate or glycidyl methacrylate,
It is at least one selected from the group of ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and maleic anhydride, and anhydrides thereof.

VLDPE is most preferred among the ethylene copolymers which are component (B) in the present invention. VLDP
E has an MFR of 0.1 to 10 g / 10 min, preferably 0.5 to 10 g / 10 min.
It is better to select from the range of 5 g / 10 min. MFR is 0.1
If less than g / 10min, the fluidity of the resin composition is inferior and 10g / 10m
If it exceeds “in”, the tensile strength and the like become low, which is not preferable.

The calcium carbonate as the component (C) in 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 if the surface treatment agent exceeds 2% by weight, further improvement of the characteristics cannot be generally expected 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. The blending amount of (C) calcium carbonate in the resin composition is 15 to 50% by weight, preferably 25 to 40% by weight. If it is less than 15% by weight, the effect of easy incineration cannot be obtained, and the texture is inferior.
If it exceeds 50% by weight, the mechanical strength such as tensile strength and dart impact strength is inferior, the feel is rough, and the texture is remarkably deteriorated. Therefore, it is preferable to select from the above range.

When the composition of the present invention is blended, it can be easily blended by a known method generally used as a conventional resin composition blending method. To give one example,
After the above components (A) to (C) and various additives are dry-blended for about 1 to 30 minutes using a mixer such as a tumbler, a ribbon blender or a Henschel type mixer, a screw having an L / D of 20 or more is used. By a continuous melt kneader such as a single screw extruder, twin screw extruder, etc.
The resin composition can be obtained by melt-mixing at an extrusion temperature of 150 to 250 ° C and extruding to prepare pellets.

As another mixing method, a part of the component (A) and / or the component (B) is mixed with the entire amount of the calcium carbonate (C), and the mixture is melt-kneaded to obtain a high concentration of the calcium carbonate. (Hereinafter referred to as “masterbatch”), and then mixing the masterbatch with the remaining components (A) and / or (B) and, if desired, various additives, by a so-called masterbatch method. A resin composition can also be obtained. In the case of the master batch method, as a resin to be mixed with calcium carbonate,
The component (B), particularly the above-mentioned (B ₁ ) ethylene / α-olefin copolymer (VLDPE) is preferred. Α with 6 or more carbon atoms
Those having an olefin as a component are more preferred. The concentration of calcium carbonate in the masterbatch is 50-90% by weight
It is. 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. 9
If it exceeds 0% by weight, the dispersion of calcium carbonate becomes insufficient, so that clogging occurs on the screen of the extruder during the production of the master batch, and the formed film becomes uneven.

As the method of forming the above resin composition into a film, a commonly used T-die film forming method, blown film forming method, water-cooled film forming method and the like are used. Can be exhibited extremely well. When an easily incinerated garbage bag is manufactured using the above film, the film thickness is 20 to 100 μm, preferably 25 to 80 μm, and more preferably 30 to 60 μm.
It is. If the film thickness is less than 20 μm, the strength is low, and if it exceeds 100 μm, the bag becomes too hard to handle, which is not preferable.

In the present invention, when the components containing components (A) to (C) are mixed and melted or molded with each other, an antistatic agent, an antifogging agent, an organic Fillers, antioxidants, lubricants, organic or inorganic pigments, UV inhibitors, dispersants, nucleating agents, foaming agents, known additives such as cross-linking agents, within a range that does not substantially impair the properties of the present invention. Can be added. In addition, in particular, additives specific to the garbage bag include repellents for animals and the like, anti-deodorants, fragrances, and the like. 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.

[0021]

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 component (C) is shown below. Component (A): high-density polyethylene (HDPE) [density = 0.946 g / cm ³ , MFR = 0.04 g / 10 min;
Product name: Nisseki Staphlen E903 (F), Nippon Petrochemical
(B) Component (ethylene copolymer): (B ₁ ): very low density polyethylene (VLDPE) [ethylene / 1-butene copolymer, density = 0.900 g / c
m ³ , MFR = 1.0 g / 10 min, Tm = 120 ° C., boiling n-
Hexane-insoluble content = 90% by weight; manufactured by Nippon Petrochemical Co., Ltd.] (B ₂ ): Ethylene-vinyl acetate copolymer (EVA) [Vinyl acetate content = 3% by weight, MFR = 0.3 g / 10 mi]
n; Trade name: Nisseki Lexlon V152, Nippon Petrochemical
Ltd.] (B _3): ethylene - ethyl acrylate copolymer (EEA) [ethyl acrylate content = 10 wt%, MFR = 3 g /
10 min; Trade name: Nisseki Lexlon A3100, manufactured by Nippon Petrochemical Co., Ltd.] (B ₄ ): Ethylene / 1-butene copolymer (EBC) [Density = 0.89 g / cm ³ , MFR = 3.6 g / 10min, Tm =
76 ° C .; trade name: Tuffmer A-4090, manufactured by Mitsui Petrochemical Industries, Ltd.) (B ₅ ): LLDPE [density = 0.922 g / cm ³ , MFR = 2 g / 10 min, Tm =
122 ° C; trade name: Nisseki Linirex AF3310,
(Nippon Petrochemical Co., Ltd.) Component (C): calcium carbonate [Average particle size = 1.7 μm, specific surface area = 13,000 cm ² /
g, surface-treated with saturated fatty acids; Trade name: BS
K-5, manufactured by Dowa Calfine Co., Ltd.]

<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) Boiling n-hexane insolubles: A sheet having a thickness of about 200 μm and a length and width of 20 mm × 30 mm is formed from a sample by hot pressing, weighed, and then extracted with boiling n-hexane for 5 hours using a double tube Soxhlet extractor. I do. After the insolubles were vacuum dried (7 hours, 50 ° C.), they were weighed, and the ratio of the insolubles to the weight before extraction was expressed in%. (7) 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 thickness of the film was slightly varied. X: The shape and size of the bubble change, and the thickness of the film also changes greatly. (8) Texture of the film: The garbage bag was grasped with the palm, and the bag was swung in an empty state, and 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 Density of component (A) = 0.950 g / cm ³ , MFR = 0.
50% by weight of high-density polyethylene of 6 g / 10 min and V of density of 0.905 g / cm ³ and MFR = 5 g / 10 min as the component (B)
The average particle size is 1. based on the resin component of 20% by weight of LDPE.
After mixing 30% by weight of calcium carbonate (C) of 7 μm with a tumbler mixer, the screw diameter was 65 mm.
Extrusion temperature 230 ° C (cylinder temperature 230 ° C, die temperature 210
° C) and pelletized through a pelletizer. Using the composition thus obtained as a raw material,
Using a blown film molding machine equipped with a single screw extruder having a screw diameter of 50 mmφ and L / D = 30, the extrusion temperature was 190 ° C. (cylinder temperature 200 ° C., die temperature 190
° C) and a blow-up ratio of 3.0 under molding conditions of 3.0.
A μm film was formed. A bag body was formed by heat-sealing the bottom of a material having a folded diameter of 450 mm and a length of 500 mm made of this film at 150 ° C. Table 1 shows the results of various tests performed on the film and the bag together with the mixing ratio.

<Examples 2 and 3> The same treatment as in Example 1 was conducted except that the compositions of the high-density polyethylene (A) and the VLDPE (B) were changed. Table 1 shows the results.

<Example 4> A treatment was carried out in the same manner as in Example 1 except that 20% by weight of the (B ₂ ) ethylene-vinyl acetate copolymer was used as the component (B).
Table 1 shows the results.

Example 5 The same treatment as in Example 1 was carried out except that 20 parts by weight of the (B ₃ ) ethylene-ethyl acrylate copolymer was used as the component (B). Table 1 shows the results.

[0027]

[Table 1]

Examples 6 and 7 The same treatment as in Example 1 was carried out with the composition shown in Table 2 except that the amount of the calcium carbonate (C) was changed. Table 2 shows the results.

<Examples 8 and 9> In mixing the component (C) calcium carbonate, (B ₁ )
A master batch containing VLDPE as a base resin and containing 80% by weight of calcium carbonate was used, the amount of calcium carbonate was the same as in Examples 6 and 7, and the composition was treated as in Example 1 with the composition shown in Table 2. Table 2 shows the results.

Example 10 When compounding calcium carbonate (C), (A) H
50% by weight of calcium carbonate using DPE as base resin
And the same treatment as in Example 1 was carried out. Table 2 shows the results.

[0031]

[Table 2]

Comparative Example 1 68% by weight of the high-density polyethylene as the component (A)
The treatment was carried out in the same manner as in Example 1, except that VLDPE as the component (B) was changed to 2% by weight. Table 3 shows the results. Poor dart impact strength and texture.

<Comparative Example 2> 34% by weight of the high-density polyethylene as the component (A)
Except that the VLDPE as the component (B) was 36% by weight,
The treatment was performed in the same manner as in Example 1. Table 3 shows the results. Poor tensile modulus and texture.

<Comparative Example 3> 10% by weight of calcium carbonate as the component (C) was blended.
The composition of Table 3 was treated in the same manner as in Example 1. Table 3 shows the results. Low tensile modulus and high heat value incineration.

<Comparative Example 4> 55% by weight of calcium carbonate as the component (C) was blended.
The composition of Table 3 was treated in the same manner as in Example 1. Table 3 shows the results. Poor tensile strength and dart impact strength, very poor texture.

Comparative Example 5 As the component (B), (B ₄ ) ethylene α having a melting point of 76 ° C.
-Except using an olefin copolymer (tuffmer), it processed like Example 1. Table 3 shows the results. Poor tensile modulus.

<Comparative Example 6> Processing was performed in the same manner as in Example 1 except that (B ₅ ) LLDPE was used as the component (B). Table 3 shows the results. Poor dart impact strength and texture.

[0038]

[Table 3]

[0039]

The easily burnable garbage bag of the present invention comprises a specific amount of (A) polyethylene having a density of 0.94 g / cm ³ or more and (B) a polymer component comprising a specific ethylene copolymer. (C)
Because it is made of a film manufactured using a composition containing calcium carbonate, it has high mechanical strength, is translucent, allows identification of contents, and has easy incineration property, that is, a low calorific value during incineration. It is.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-17636 (JP, A) JP-A-60-92311 (JP, A) JP-A-7-53791 (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) 25 to 80% by weight of polyethylene having a density of 0.94 g / cm ³ or more and (B) at least one ethylene copolymer selected from the following (B ₁ ) to (B ₃ ): 2 to 40% by weight (B ₁ ) density 0.8
6 g / cm ³ or more and 0.91 g / cm less than ^3, the melting point 100 ° C.
Ethylene-α-olefin copolymer having a boiling n-hexane insoluble content of 10% by weight or more, (B ₂ )
50-85% by weight of a resin component comprising a vinyl ester copolymer and (B ₃ ) an ethylene-α, β-unsaturated carboxylic acid alkyl ester copolymer (provided that the amount of the component (A) ≧
(B) amount of component) and (C) an easily incinerated garbage bag made of a film produced using a resin composition containing 15 to 50% by weight of calcium carbonate. 2. The resin composition according to claim 1, wherein the resin composition is blended using a master batch composed of (B) 10 to 50% by weight of an ethylene copolymer and 50 to 90% by weight of calcium carbonate. 2. The easily incinerated garbage bag according to 1.