JP2002241598A - Film produced from recovered pet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that polyethylene terephthalate(PET) recycled by crushing recovered PET bottles is inferior in moldability and characteristics. SOLUTION: A film is obtained by modifying and polymerizing recycled polyethylene terephthalate(PET) obtained by crushing recovered PET with a cross-linking agent and a cross-linking catalyst, compounding the modified PET with a thermoplastic resin in a weight ratio of 80%:20% to 20%:80%, and then forming the composition into the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recycled film from a used PET bottle and a method of recycling the same, and more particularly to a recycled film suitable for a garbage bag or a shopping bag (shopping bag).

[0002]

2. Description of the Related Art Fruit juice, soft drinks, water, alcoholic beverages, soy sauce, vinegar,
Polyethylene terephthalate (PET) containers used to contain liquids, powders, or granules of cosmetics, pharmaceuticals, etc., are currently produced in plastic bottles in Japan at a rate of more than 200,000 tons per year and are consumed in large quantities. . Pets are high-purity substances, except that they contain a small amount of residual catalyst,
Used PET bottles are removed and washed after removing attached labels and contaminants, and then crushed into flake-like powders. Halve. For this reason,
When this is heated and melted, it becomes a smooth state and the viscosity is insufficient, so that molding techniques such as extrusion molding, inflation molding and casting molding cannot be applied, so that the fields in which it can be reused are limited. as a result,
Most of the pets that have been collected are incinerated or left unstacked, and the effective use of pets, a valuable fossil resource, is currently limited.

[0003] The flake-like powder obtained by washing and pulverizing the recovered PET bottle in this manner has a molecular weight reduced to about half, and when melted, has a very low viscosity when melted, and is extruded, inflation-molded, and cast. It does not have the viscosity necessary for molding by molding methods such as molding, and cannot produce PET bottles of the original quality. The present invention provides a novel film using this resin.

On the other hand, polyethylene films are used as plastic bags and garbage bags because they are thermoplastic and have excellent flexibility, airtightness and antibacterial properties. Shopping bags are ultimately collected as garbage bags and incinerated. However, the problem with burning polyethylene is high calorie, which has the problem of damaging the incinerator.Magnesium carbonate, which is said to have an endothermic or slow-burning action to reduce calories in many municipalities And an opaque or translucent polyethylene bag (polybag) kneaded with a pigment such as calcium carbonate. However, since a large amount of ash remains in an incinerator, securing a disposal place for the ash is a major problem.

Under these circumstances, attempts to improve the quality of recycled pets from collected PET bottles have been made.
O98 / 44019. That is,
(A) Recycled pet 100 obtained by crushing the collected pet
Parts by weight, and (b) a binder comprising a mixture of 0 to 100% by weight of a compound having two epoxy groups in a molecule and 100 to 0% by weight of a compound having three epoxy groups in a molecule, (C) A metal salt of a carboxylic acid, preferably a sodium salt, more preferably a manganese salt is mixed with a binding reactant consisting of 0.01 to 5 parts by weight, and heated to a melting temperature or higher of the regenerated pet to give a swell of 1 to 5. It describes a modified pet with an increased molecular weight of 200%. This modified pet is formed into pellets and is called Neopet under the name of Dainippon Resin Laboratories Co., Ltd. (DJK Techno S
Science Laboratories Inc).

[0006]

SUMMARY OF THE INVENTION However, WO9
The modified pet described in 8/44019 is suitable for some methods such as extrusion molding, but has a problem that it is not sufficiently suitable for extrusion, inflation molding, and casting molding used for continuous molding. Further, the conventional polyethylene shopping bag or garbage bag has a problem that the calorific value at the time of incineration is large and the furnace is damaged. A garbage bag containing an inorganic pigment such as magnesium carbonate has a problem that a large amount of residual ash is generated. Accordingly, an object of the present invention is to recycle a plastic film, particularly a plastic bag and a garbage bag, using the above-mentioned modified pet from a PET bottle. Another object of the present invention is to improve the moldability of a modified pet, improve the properties of a film formed therefrom, and reduce the amount of heat generated, thereby making it unnecessary to add an inorganic pigment.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a modified pet made by modifying a recycled pet obtained by pulverizing recovered polyethylene terephthalate and polymerizing the same, and adding a thermoplastic resin in a weight ratio of 80%: 20%. A method of forming a film by blending at a ratio of ２０20%: 80% and a film obtained thereby. Here, the modified pet is composed of (a) 100 parts by weight of a recycled pet obtained by crushing the collected pet, (b) 0 to 100% by weight of a compound containing two epoxy groups in the molecule, and Compound 10 containing three epoxy groups
A binder consisting of a mixture of 0 to 0% by weight and a binding reagent consisting of (c) 0.01 to 5 parts by weight of a metal salt of a carboxylic acid are mixed, and heated to a melting temperature of a regenerated pet or higher, and the swell is reduced. A modified pet with increased molecular weight of 1-200%. The thermoplastic is preferably a linear low density polyethylene. Also, depending on the required properties, the properties of the film can be improved by co-extrusion with the second thermoplastic resin to form two layers. The pet product usually has a direct printing layer, but such a printing part is a step of pulverizing the recovered polyethylene terephthalate washed at a temperature of 85 to 98 ° C. with a weak alkaline solution to obtain the recycled pet. By adding, it can be easily removed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, a "recovered pet" is a collection of polyethylene terephthalate and other used pets known as PET bottles and the like, and the surface thereof is often directly printed. . As used herein, the term "recycled pet" means that the collected pet is washed according to a standard method,
It refers to a pet from which the printing ink has been removed and flake-like particles obtained by crushing. In the present invention, "modified pet" refers to
It refers to a regenerated pet obtained by polymerizing a regenerated pet with a binder and a binding reaction catalyst. Preferably, (a) 100 parts by weight of a regenerated pet obtained by crushing a collected pet, and (b) 2
0 to 100% by weight of a compound containing three epoxy groups and a compound 100 to 0 containing three epoxy groups in a molecule.
% By weight of a mixture consisting of a mixture of a binder and (c) a binding reagent consisting of 0.01 to 5 parts by weight of a metal salt of a carboxylic acid.
A modified pet with an increased molecular weight of 200%. The thermoplastic resin to be incorporated into the modified pet in the present invention is not limited, but linear low density polyethylene is particularly preferred. On the other hand, the thermoplastic resin to be co-extruded is not limited, and may be the same as or different from the first thermoplastic resin.
In addition, the present invention can recover the printing ink easily by recovering the recycled polyethylene terephthalate by recovering the recovered PET bottle through a recovery step including a step of washing the recovered PET bottle with a weak alkaline solution at a temperature of 85 to 98 ° C. Can provide good produced pet flake powder.

In order to reuse the recovered pet, it is pulverized into a regenerated pet and, if necessary, further pelletized. However, the molecular weight of the recovered pet is about half of its original value, the fluidity is high, the molding is difficult, and a specific shape of the recovered pet is difficult. There is a mass production method only for the production of blow-molded products and the like, and there is a problem that recycling as a plastic bottle is expensive, and the quality of the product is lower than that of the original plastic bottle and the competitiveness is reduced. As described above, modified pets known as neopets also have insufficient viscosity and their use is limited. Therefore, using a film forming method such as inflation molding, extrusion molding, cast molding, etc., which is easy to mold and suitable for mass production, recycles and reuses pets as films for packaging films, bags, and other uses. It is necessary to have a viscosity suitable for In the present invention, a thermoplastic resin, particularly a linear low-density polyethylene (hereinafter, referred to as LLDPE) is blended in a modified pet at a weight ratio of 80%: 20% to 20%: 80% by weight ratio, and formed into a film by inflation molding. This problem is solved by providing a reproduction film.

First, in order to make a recycled pet from the collected PET bottle, the cap or label is removed, washed,
Dry and crush to make chips. Removing the printing ink during washing is essential for improving the quality of the recycled pet. Therefore, the PET bottle is first thoroughly washed with water, and then the weak alkaline aqueous solution is heated to a temperature of 85 to 98 ° C., for example, about 92 ° C.
When heated to 10 ° C. and washed for about 10 to 30 minutes, for example, about 20 minutes, the printed layer easily peels off from the surface of the PET bottle. It is then washed with water, dried, ground and flaked. Next, (a) a recycled pet 1 obtained by crushing the collected pet
(B) a binder comprising a mixture of 0 to 100% by weight of a compound having two epoxy groups in the molecule and 100 to 0% by weight of a compound having three epoxy groups in the molecule. , (C) a binding reagent consisting of 0.01 to 5 parts by weight of a metal salt of a carboxylic acid, and heating above the melting temperature of the regenerated pet to an increased molecular weight with a swell of 1 to 200%.

In the above, the binder of the component (b) becomes a chain extending component of the regenerated pet, and the melt tension of the pet increases the melt viscosity. In addition, a branched chain is formed by this component, and swell (swelling degree) increases. Thereby, the moldability at the time of melting is improved. The component (c) is an alkali metal carboxylate,
Carbonates and bicarbonates, alkaline earth metal carboxylate, aluminum zinc or manganese carboxylate, manganese carbonate and the like.

A specific example of the modified pet is WO98 / 4401.
See No. 9 for reference. The modified pet obtained by the same method is commercially available as NEOPET (trade name) from Dainippon Tree Research Institute Co., Ltd. (Kohoku-ku, Yokohama-shi).

Although the modified pet is not suitable for extrusion molding, casting molding or inflation molding even if it is melted, it is blended with a thermoplastic resin, especially linear polyethylene LDLPE, and is used for inflation molding, cast molding, and extrusion. Obtain a viscosity that allows molding. Thus, it is possible to stably produce a reproduced film.

The thermoplastic resins usable here include high density polyethylene (HDPE) and polypropylene (P
P), low density polyethylene (LDPE), linear low density polyethylene LLDPE, and the like. Among them, the use of LLDPE is recommended. LLDPE has a density of 0.88
0.96 g / cm, melting index 0.1-100 g / 1
Those having 0 minutes have good moldability, and those having a heat seal strength of 0.6 kg / mm width at 110 ° C. or less are good, and impart the moldability and heat sealability to the modified pet. Such LLDPE is disclosed in, for example,
264246. Any commercially available LLDPE can be used. For example, there is Harmolex LL (trade name) NF275B commercially available from Japan Polyolefin Co., Ltd. PDPE includes JF124 and the like. By adding 20% or more, preferably 30% or more of a thermoplastic resin, inflation molding becomes possible, and heat sealability is also obtained. On the other hand, if 80% or more of the thermoplastic resin is blended, the amount of pets to be regenerated is reduced. Therefore, in order to regenerate as much as possible, it is necessary to limit the amount to 80% or less, preferably 70% or less.

In the present invention, a laminated film may be formed by employing a co-extrusion method together with the second thermoplastic resin. Depending on the resin selected, the flexibility of the film is enhanced and the mechanical properties are improved. The thermoplastic resin may be a recycled pet or polyethylene. Recycled pets cannot be molded by ordinary film forming methods due to their low viscosity, but two-layer molding is possible using a film of the mixed resin according to the present invention. On the other hand, when the mixed resin according to the present invention is co-extruded with polyethylene, the advantageous properties of polyethylene can be utilized.

The heat-sealing property is necessary to heat-seal a tubular film flattened at regular intervals in order to form a blown film into a bag shape. Of thermoplastic resin such as LLDPE mixed with 20% or more, especially 30%
% Or more.

Another requirement is to have a low calorific value so as not to damage the incinerator when discarded and incinerated again. When used in the blending ratio of the present invention, the inflation film obtained from the pet and the thermoplastic resin, particularly LLDPE, has a calorific value at the time of combustion considerably smaller than the calorific value known for the conventional polyethylene bag. In addition, since there is no need to knead inorganic solids such as magnesium carbonate and calcium carbonate into the compound, there is almost no incineration residue.

Since the physical properties such as elasticity and elongation change greatly depending on the mixing ratio of the modified pet and the thermoplastic resin, if the mixing ratio is appropriately selected according to the use of the blown film of the present invention, the desired physical properties can be obtained. Can be easily designed. As can be seen from the following examples, the dimensional stability of the film produced from the blend of the modified pet and the thermoplastic resin is very high, and gives a beautiful finish when printing a design or the like.

[0019]

EXAMPLES The present invention will be described with reference to examples. Example 1 (Single-layer film) A modified pet called NEO Pet (trade name) by Dainippon Tree Research Institute Co., Ltd. (Kohoku-ku, Yokohama) was used as a raw pet (sample NS0613-05, UV1603-
12). This modified pet is obtained by crosslinking and modifying 85% by weight of PET flake and 15% by weight of the above-mentioned epoxy binder with 10% by weight of the above-mentioned catalyst. On the other hand, Harmolex LL (trade name) grade NF275B commercially available from Nippon Polyolefin Co., Ltd. as LLDPE pellets mixed therewith, and JF124 which is LDPE
B was used. On the other hand, Harmolex LL (trade name) grade NF275, which is commercially available from Nippon Polyolefin Co., Ltd. as LLDPE pellets to be mixed therewith.
B and JF124B were used as LDPE. The compounding ratio is as shown in Table 2. These raw material compositions were fed to a raw material supply tank of an inflation molding machine at a resin temperature of 27.
The mixture was heated and melted at 3 ° C. and inflation-molded. Various properties of the obtained film were measured under the measurement conditions shown in Table 1, and MD
Table 2 shows film properties in the direction (main axis direction), Table 3 shows film properties in the TD direction (perpendicular direction), and Table 4 shows heat seal properties. The heat seal characteristics were measured by developing the upper and lower sheets of the heat seal portion, cutting out the sample to the dimensions shown in Table 1 with the seal portion interposed therebetween, and measuring.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

As can be seen from Tables 2 and 3, the films of the present invention could be formed by inflation molding despite containing a large amount of modified pets. When compared with a conventional polyethylene film (garbage bag), the maximum stress is the same when there are many neopets, and there is no problem in the film strength. The maximum stress decreases as the neopet decreases. On the other hand, the maximum point elongation is extremely small as compared with a garbage bag and has excellent dimensional stability, and is suitable for printing. Therefore, it is possible to design according to the purpose by changing the mixing ratio. It can be seen that the modulus of elasticity is equivalent to that of polyethylene when there are many modified pets, and generally has equal or higher flexibility. Next, from Table 4, it can be seen that the film of the present invention is inferior to polyethylene film in terms of seal strength. However, if PET is used excessively, sufficient seal strength can be obtained, and the film is easily peelable into packaging films such as snacks. This is rather preferred when the required seal is required. In addition, it can be used without any problem in applications that do not require heat sealing. On the other hand, in the case where the packaging bag requires heat sealability, it can be understood that a problem-free seal strength can be obtained by setting the pet content to 45 to 80%, particularly 50 to 70%.

Next, NS0613 / N used in the present invention
A combustion test of F275B = 70/30 was performed. Tubular electric furnace method (JIS K2541) as a method of generating combustion gas
850 ° C, air supply 300ml /
Under the condition of min, 0.3 g of the sample was burned, and the generated gas, ash content, and calorific value were measured. The following results were obtained. Hydrogen chloride 0.27 mg / g Sulfur oxide Not detected Nitrogen oxide 0.28 mg / g Cyanide Not detected Total heat generation 28,700 J / g (6860 cal / g) Ash 0.08% From now on, the calorific value is polyethylene (11000 cal /
The value is considerably smaller than that of g). Or polyethylene also has essentially no ash.

Example 2 (Co-extruded film) 70% by weight of Neopet IK07263-1 (MFR: 12) and 30 LLDPE (Harmorex NF275B) 30
Wt% of the mixture is melted at about 275 ° C.
LDPEJF124B was melted at 275 ° C., and the former was coextruded as an outer layer and the latter as an inner layer. Die width 150
mm, and the lip thickness was 1.0 mm. This enabled two-layer molding. Table 5 shows the properties of the obtained two-layer film.

[0027]

[Table 5]

According to Table 5, Neopet IK07263-
1 (MFR: 12) 70% by weight and a mixture of 30% by weight of LLDPE (Harmorex NF275B) and LLDP
The two-layer film of EJF124B has excellent flexibility since the elastic modulus is not so high.

[0029]

According to the present invention, an inflation molded film can be obtained by using a recycled material recovered from a PET bottle. The heat sealability is also sufficient, and a bag can be manufactured. Further, since the calorific value is small and ash is hardly generated, no great burden is imposed on the incinerator when burning as waste.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 5/18 CFD C08J 5/18 CFD 4J002 C08L 23/08 C08L 23/08 // B29K 23:00 B29K 23 : 00 67:00 67:00 105: 16 105: 16 105: 26 105: 26 (72) Inventor Koichiro Ikuta 1 Mashino, Osachi-cho, Okawa-gun, Kagawa Prefecture F-term (reference) 4F070 AA47 AB26 AC40 AC87 AE08 GA06 GB02 4F071 AA19 AA46 AH04 BB09 BC01 4F100 AH02A AH02H AK01A AK01B AK42A AK63A AL05A BA02 BA10A BA10B BA15 CA02A CA30A EH202 GB15 JB16A JB16A JA00 A03A01 AA37A 4J002 BB03X BB12X CF06W

Claims (9)

[Claims] The modified PET obtained by pulverizing the recovered polyethylene terephthalate with a cross-linking agent and a cross-linking catalyst to form a polymerized pet is added with a thermoplastic resin in a weight ratio of 80%: 20% to 20%: A film mixed at a ratio of 80% and formed into a film by film forming. 2. The modified pet comprises: (a) 100 parts by weight of a recycled pet obtained by pulverizing a collected pet; and (b) 0 to 100% by weight of a compound containing two epoxy groups in a molecule. And a compound 1 containing three epoxy groups in the molecule
A binder consisting of a mixture of 100 to 0% by weight and a binding reagent consisting of (c) 0.01 to 5 parts by weight of a metal salt of a carboxylic acid are mixed, and heated to a temperature higher than the melting temperature of the regenerated pet, and 2. The film of claim 1 which is an enhanced molecular weight modified pet that is 1-200%. 3. The film according to claim 1, wherein the thermoplastic resin is a linear low-density polyethylene. 4. The film according to claim 1, which is co-extruded with a second thermoplastic resin to form a film. 5. A regenerated pet obtained by pulverizing the recovered polyethylene terephthalate to obtain a modified pet obtained by modifying with a crosslinking agent and a catalyst into a polymerized pet, and further comprising a thermoplastic resin in a weight ratio of 80%: 20% to 20%. %: Blended at a rate of 80%,
A method for producing a film by forming a film by a film forming method. 6. The method according to claim 5, wherein the thermoplastic resin is a linear low-density polyethylene. 7. The modified pet comprises: (a) 100 parts by weight of a recycled pet obtained by crushing the collected pet; and (b) 0 to 100% by weight of a compound containing two epoxy groups in a molecule. And a compound 1 containing three epoxy groups in the molecule
A binder composed of a mixture of from 0 to 0% by weight and a binding reagent composed of (c) a metal salt of a carboxylic acid, preferably a sodium salt, more preferably 0.01 to 5 parts by weight of a manganese salt are mixed and regenerated. 7. The method of claim 5 or 6, wherein the pet is a modified pet of increased molecular weight, heated above the melting temperature of the pet and having a swell of 1 to 200%. 8. The process for producing a film according to claim 5, wherein the film is co-extruded with a second thermoplastic resin. 9. The film according to claim 5, comprising a step of washing the recovered polyethylene terephthalate with a weak alkaline solution at a temperature of 85 to 98 ° C., drying and pulverizing to obtain the recycled pet. Manufacturing method.