JP2000000878A - Resin bottle with label stuck and its recycling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bottle with a label stuck from which reclaimed pellets of high purity can be obtained, a method for reclaiming the label from which ink was removed and the bottle, and the reclaimed pellets. SOLUTION: In a blow-molded polyester resin bottle with a label stuck which has an ink layer which can be removed in alkaline hot water at least on one side of a thermoplastic polymer film and in which an intermediate layer for removing ink in alkaline hot water exists between the ink layer and a backing layer, the content of an ethylene terephthalate cyclic trimer oligomer in the resin of the bottle is 1.0% or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottle provided with a label capable of removing printed ink, a method for regenerating them, and a regenerated pellet thereof.

[0002]

2. Description of the Related Art In recent years, the amount of bottles used has been increasing year by year from bottles made of glass, metal or the like to polymers, particularly bottles made of thermoplastic polymers, because of their excellent fracture resistance, light weight, transparency and the like. ing. In particular, the production of polymer bottles in the beverage field is remarkable, and is used in large quantities from small bottles to large bottles. Above all, the use amount of bottles containing polyethylene terephthalate as a main component (hereinafter abbreviated as “PET bottle”) has been remarkably increased.

On the other hand, recent awareness of global environmental issues has raised the need to deal with the recycling problem of bottles made of thermoplastic polymers. There is great interest in recycling bottles made of thermoplastic polymers, especially PET bottles, and there is a need for an early establishment of a recycling system.
In general, a PET bottle is provided with a label such as a polyolefin-based stretch label, a heat-shrinkable label made of polyester, polystyrene, vinyl chloride, or the like, and a tack label made of a polypropylene film or the like. PE
Regarding the recycling of T-bottles, they are usually collected from ordinary consumers with the label attached and brought to a recycling company.
The removed bottle is subjected to primary pulverization after washing to remove the label, but the pulverized material still contains a large amount of label. Therefore, regenerated pellets have been obtained through secondary pulverization, liquid specific gravity separation of labels, dehydration / drying, wind specific gravity separation, and pelletizing steps. FIG. 2 shows a process of recovering a thermoplastic polymer as a pellet from a typical conventional bottle with a label.

In the above-mentioned conventional label and the method of recycling a bottle equipped with the label, the label is separated by various separation steps, but if the purity of the recycled thermoplastic polymer is improved, the recycling ratio of the raw material is reduced. There is a problem. Further, as impurities in the regenerated thermoplastic polymer after these steps, there are label resins, inks, and the like. In particular, even if the amount of the ink is small, there is a problem that the entire regenerated pellet is colored.

Therefore, in order to efficiently recycle the bottle, it is necessary to prevent the label and the ink of the label from being mixed with each other in order to improve the purity of the recycled thermoplastic polymer. Up to now, the thermoplastic polymer that is the material of the label has been improved, and the specific gravity of the polymer is lower than that of PET, such as polystyrene and polyethylene.
Labels of polyolefins such as polypropylene have been proposed, but there is a problem that complete separation is impossible since the ink layer is applied and the specific gravity is not low.

[0006] Further, there has been proposed a polyester label of the same kind which does not cause a problem even if it is mixed in a PET bottle, but the ink layer cannot be separated, and the problem that the recycled pellet is colored remains unsolved. In recent years, at exhibitions, etc., a method has been proposed in which a label capable of easily removing the ink layer is attached to a bottle, and after removing the label ink layer in alkaline hot water, the label and the bottle are regenerated without being separated. was suggested.

[0007] This method facilitates the recycling of recovered bottles into pellets and eliminates the problem of coloring. However, the purity of the recovered pellets is still insufficient, and particularly, oligomers including cyclic trimer oligomers Is often generated in recycled pellets, and this oligomer often adheres to dies and nozzles when spinning, extrusion molding, injection molding, etc. are performed using recycled pellets, and often adheres to the product itself. Was dropped. For this reason, the regenerated pellets obtained by this method are also difficult to handle and have limited uses.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is no need to separate a label when a labeled bottle is collected and a recycled pellet is produced using the bottle, and the obtained recycled pellet is derived from ink. No coloration of pellets,
Another object of the present invention is to provide a labeled resin bottle which is free from contamination of a mold and a nozzle by an oligomer and deterioration of product quality in a step of obtaining a product using recycled pellets.

[0009]

That is, the present invention relates to a thermoplastic polymer film having an ink layer on at least one surface thereof which can be removed in alkaline hot water, and an intermediate layer for removing the ink in alkaline hot water, which is an ink layer. A hollow molded bottle made of a polyester resin having a label attached between the resin and the base material layer, wherein the content of the cyclic trimer oligomer of ethylene terephthalate in the resin of the bottle is 1.
It is a hollow molded bottle characterized by being 0% or less.

[0010] The resin of the hollow molded bottle may have the condensation polymerization catalyst deactivated.

Here, the ink layer that can be removed in alkaline hot water is obtained by cutting 1 g of a sample label into 1 cm square,
After stirring in a 3% solution of NaOH (90 ° C.) for 30 minutes, washing with water and drying, the ink layer has an ink removal rate of 90% or more. The term "intermediate layer for removing ink in alkaline hot water" means that the intermediate layer is also removed in the same process.

In this case, the label may be such that the thermoplastic polymer film is a heat-shrinkable film.

[0013] In the label, the heat-shrinkable film may be a polyester-based heat-shrinkable film.

[0014] In the label, the heat shrinkage of the polyester heat shrinkable film may be 30 to 80%. Here, the heat shrinkage is a shrinkage measured by immersion in hot water at 95 ° C. for 10 seconds.

[0015] The label may contain a compound whose ink layer and / or intermediate layer swells or is soluble in alkaline hot water.

[0016] The bottle is characterized by having the label attached thereto.

In the bottle having the above structure, the ink layer and the intermediate layer on the label can be easily removed, so that the thermoplastic polymer can be easily reused as a bottle with a label.

After the ink layer and the intermediate layer are easily removed from the bottle of the present invention having the above-described structure, the bottle and the label can be simultaneously subjected to the recovery step and reused.

Further, the bottle may have a heat shrinkage rate of the attached label in a circumferential direction of the bottle of 0.1% or more and less than 80%.

In the bottle having the above structure, the interface with the ink layer is peeled off by the heat shrinkage of the heat-shrinkable film constituting the label in the washing step, and the bottle is easily removed.

[0021] In the ink removing method, the label may include:
The ink layer and the intermediate layer on the label are removed by dipping in alkaline hot water.

In the ink removing method having the above-described structure, the ink layer and the intermediate layer can be easily separated from the film constituting the label.

The ink removing method is characterized in that the bottle having the label attached thereto is immersed in alkaline hot water to remove the ink layer and the intermediate layer on the label.

In the ink removing method having the above configuration, the label and the bottle from which the ink layer and the intermediate layer have been removed can be directly transferred to the thermoplastic polymer recovery step.

In addition, the method for recycling a bottle with a label is as follows: the label from which the ink layer and the intermediate layer have been removed by the method described above;
It is characterized by being melted and regenerated together with the bottle having the label attached.

In the method of recycling a bottle with a label having the above structure, the label and the bottle without the ink layer and the intermediate layer can be directly transferred to the recovery step and recycled.

Further, the regenerated pellets are obtained by the above method.

The recycled pellets having the above-mentioned structure are excellent recycled pellets which can be reused for various moldings without containing substantially any ink, and are suitable for effective use of resources.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a bottle equipped with a label according to the present invention and a method for regenerating the bottle.

The bottle of the present invention has an ink layer on at least one side of a thermoplastic polymer film which can be removed in alkaline hot water, and an intermediate layer for removing the ink in alkaline hot water comprises the ink layer and the base material. It is a hollow molded bottle made of polyester resin to which a label existing between the layers is attached. First, at least one surface of the thermoplastic polymer film has an ink layer that can be removed in alkaline hot water, and an intermediate layer that removes the ink in alkaline hot water exists between the ink layer and the base layer. Will be described.

The base film of the label used for the bottle is not particularly limited as long as it is a thermoplastic film.
In addition, there is no restriction as to whether the film is a shrinkable film, a non-shrinkable film, or a stretchable film.
Specifically, as the shrinkable film, polyethylene,
Examples include uniaxial or biaxially stretched films such as polyolefin-based films such as polypropylene, polystyrene-based non-foamed and foamed films, polyvinyl chloride films and polyester-based films. Examples of non-shrinkable films include polyolefin films such as polyethylene and polypropylene, polystyrene films, polyvinyl chloride films, polyvinylidene chloride films, polyamide films such as nylon-6 and nylon-66, polyester films and other polyphenylene sulfides. And unstretched, uniaxial or biaxially stretched films such as heat-resistant engineering plastic films such as polyetheretherketone. Preferably, as the material of the label to be attached to the body of the PET bottle, a polyolefin-based film, a polystyrene-based film, and a polyester-based film which can be mixed into the recovered pellets without any problem when the pulverized material is easily separated in liquid by specific gravity. No. Further, particularly preferably, a polyester film which does not require specific gravity separation and air separation is used since the ink layer may be mixed with the recovered pellets if the ink layer is washed and removed.

More preferably, a heat-shrinkable polyester film is preferably used, in which the interface between the film and the ink layer is peeled off by the heat shrinkage of the film in the washing step, so that the film is easily removed. It is preferable that the heat-shrinkable label attached to the bottle by heat shrinkage still has residual shrinkage. After being removed from the bottle and immersed in 95 ° C. hot water for 10 seconds, the heat measured in the radial direction of the bottle The shrinkage is 0.
It is preferably 1% or more and less than 80%. When the heat shrinkage is less than 0.1%, the force generated at the interface is reduced due to the shrinkage of the ink layer and the thermoplastic film, so that the ink falling rate is reduced. On the other hand, when the heat shrinkage is 80% or more, the label is bent. And the ink removal rate decreases, which is not preferable.

A method for producing a heat-shrinkable polyester film, which is particularly preferable for use as a base film for a label, and the properties thereof are described below.

In the polyester constituting the heat-shrinkable polyester film, the main acidic component is usually terephthalic acid or 2,6-naphthalenedicarboxylic acid, and the main glycol component is usually ethylene glycol or tetramethylene glycol. However, there is no problem even if the polyester is mainly composed of another acidic component and a glycol component. Further, as the acidic component that can be copolymerized, isophthalic acid, cyclohexanedicarboxylic acid,
2,6-Naphthalenedicarboxylic acid, terephthalic acid and the like can be optionally used. Further, as a glycol component that can be copolymerized, tetramethylene glycol, ethylene glycol, trimethylene glycol, cyclohexane dimethanol, or the like can be arbitrarily used.

A film obtained by using such a polymer by an arbitrary method such as an extrusion method or a calendar method is stretched in one direction by 2.5 to 7.0 times, preferably 3.0 to 6.0 times. ,
The film is stretched 1.0 to 2.0 times or less, preferably 1.1 to 1.8 times in the direction perpendicular to the above direction. Stretching in the first direction is performed as a large requirement that has an effect to obtain a high heat shrinkage, and stretching in the direction perpendicular to the first direction is performed by first stretching the film in one direction. It is extremely effective in solving poor impact resistance and tear resistance.

However, the heat shrinkage rate of the heat shrinkable film in the main shrinkage direction is about 30 to 80%, but when stretched more than 2.0 times in the direction perpendicular to the initial direction, the heat shrinkage direction becomes The heat shrinkage in the perpendicular direction also becomes too large, and the finish of the film surface after the heat shrinkage becomes wavy. To suppress the waving of the film, the heat shrinkage in the direction perpendicular to the main shrinkage direction is 15% or less, preferably 8 to 9% or less.
More preferably, it is recommended to be 7% or less. There is no particular limitation on the stretching means, and methods such as roll stretching, long interval stretching, and tenter stretching are applied, and the shape may be flat or tubular.

The stretching is performed by sequential biaxial stretching, simultaneous biaxial stretching, monoaxial stretching or a combination thereof.
Further, for a film used for a label, for example, stretching is performed in one axis, one axis in the horizontal direction, two axes in the vertical and horizontal directions, etc. It is effective to use biaxial stretching, and the order may be any order. When the simultaneous biaxial stretching method is used, the stretching order may be any of vertical and horizontal simultaneous, vertical and horizontal advance. The heat setting after stretching is performed according to the purpose, but it is recommended to pass through a heating zone of 30 to 150 ° C. for about 1 second to 30 seconds in order to prevent dimensional change under high temperature in summer. You. Further, the stretching may be performed up to 70% before and / or after such processing. In particular, it is preferable to expand in the main direction and relax in the direction perpendicular to the main contraction direction, and it is better not to perform the expansion in the perpendicular direction.

In order to exhibit suitable properties for a shrinkable film used in a label used for a bottle equipped with the label of the present invention, not only the above-mentioned stretching ratio but also the average glass transition point (Tg) of the polyester or more is required. Preheating and stretching at a temperature of, for example, about Tg + 80 ° C. can also be mentioned as an effective means. In particular, the processing temperature in the main direction stretching (main shrinkage direction) is extremely low in order to suppress the heat shrinkage in the direction perpendicular to the direction and bring the minimum value to the temperature range of 80 ± 25 ° C. as described above. is important. Further, after stretching and after stretching, the film is cooled while applying stress to the film while keeping the film in tension, or by further cooling, the shrinkage characteristics become better and more stable.

The film thus obtained preferably has a plane orientation coefficient of 100 × 10 ⁻³ or less. If the plane orientation coefficient exceeds 100 × 10 ⁻³ , the sheet is easily broken by an external impact force, and is easily broken even by a slight damage. On the other hand, the birefringence is 15 × 10 ^{−3 to} 160 × 10 ^−3.
When the birefringence is less than 15 × 10 ⁻³ , the heat shrinkage and shrinkage stress in the longitudinal direction are insufficient, and when it exceeds 160 × 10 ⁻³ , the scratch resistance and the impact strength are reduced, and the film has Even so, the effectiveness decreases in practical use. The thickness of the thermoplastic polymer film used in the label of the present invention is 6 to 250 μm.
The range of m is practical.

The label used for the bottle of the present invention has an ink layer on at least one side thereof, and the ink layer can be removed in alkaline hot water. here,
An ink layer that can be removed in alkaline hot water is an ink layer in which 1 g of a sample label is cut into 1 cm squares, stirred in 100 cc of a 3% NaOH solution (90 ° C.) for 30 minutes, washed with water and dried, and the ink removal rate is 90%. Means The reason for the removal is that the ink layer is mainly swelled or dissolved (hereinafter, also referred to as finely dispersed) in alkaline hot water.
Practically, washing with weak alkaline warm water is usually performed for about 30 minutes, and it is sufficient that the ink layer falls off during that time.

The method for imparting the above properties to the ink layer is not particularly limited. For example, inks which are soluble or swellable in alkaline hot water can be prepared by using commonly used inks, for example, color bodies made of pigments or dyes. A method in which a binder and a volatile organic solvent are added to an ink containing the constituents is exemplified. Compounds soluble or swellable in alkaline hot water include inorganic salts such as sodium chloride, sodium sulfate, potassium nitrate, sodium acetate and ammonium sulfate, organic acids such as ascorbic acid, sebacic acid and azelaic acid or salts thereof, and polyethylene oxide. And polyethers such as polytetramethylene oxide, polyvinyl alcohol and polyacrylic acid or metal salts thereof, and copolymers thereof. Examples of the compound include those which are liquid at room temperature, and specifically, methyl alcohol, ethyl alcohol, isopropyl alcohol,
n-propyl alcohol, isobutyl alcohol, te
rt-butyl alcohol, cyclohexyl alcohol,
Alcohols such as benzyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol glycerin, monomethyl, monoethyl, monopropyl, monobutyl ether or polymethyl alcohol such as pentaerythritol or monomethyl, monoethyl ester, etc.
In addition, dioxane, acetone, methyl ethyl ketone,
Examples include diacetone alcohol, dimethylformamide, and tetrahydrofuran. Among them, those having a high boiling point are preferable because they need to remain in the ink layer, and specifically, those having a boiling point of 50 ° C or more are preferable,
Further, monoalkyl ethers of polyhydric alcohols are particularly preferred because of their solubility in alkaline hot water.

The content of the above compound as a residual amount in the ink layer is preferably 0.0001% by weight or more and 50% by weight or less, and the weight may be changed depending on the compound. When the content is less than 0.0001% by weight, the ink does not fall in the washing step, and the object of the present invention tends to be difficult to achieve. On the other hand, if the content exceeds 50% by weight, mechanical properties such as scratch resistance of the ink layer are undesirably deteriorated.

The ink containing the above compound used for the label used for the bottle of the present invention comprises an ink pigment, a binder, a solvent and the like. Examples of the binder include a nitrocellulose type, a chlorinated polypropylene type and a chlorinated polypropylene type.
Polyester, acrylic, polyester urethane and acrylic urethane binders are used. In particular, for the polyester film, an ink having a polyester, acrylic, polyester urethane or acrylic urethane binder is preferable. The pigment for coloring the ink is not particularly limited, and a commonly used pigment may be used. The ink used in the present invention is
If necessary, additives such as a weathering agent, a fluorescent brightener, a lubricant, and a crosslinking agent may be contained.

As a printing method of the ink for producing the label used for the bottle of the present invention, a known method can be used. For example, gravure printing, flexographic printing, screen printing and the like can be mentioned. The thickness of the ink layer is preferably from 0.1 μm to 100 μm. 0.1μ
If it is less than m, ink coloring is insufficient, while if it exceeds 100 m, the ink layer becomes brittle and easily cracks.

In the present invention, the ink layer is removed from the label by immersing the label in alkaline hot water. Practically, after cutting 1 g of the label to 1 cm or less, Na at 90 ° C.
It can be removed by stirring for 30 minutes or more in 100 cc of a 3% OH solution. After washing, filtration, washing with water and drying, the ink removal rate is 90%.
% Or more. Specifically, the form in which the label is pulverized from the viewpoint of label processing capacity and processing equipment is preferable, and the size of the pulverized film is 0.1.
It is preferably not less than mm square and not more than 10 cm square. If it is less than 0.1 mm square, the efficiency in the subsequent filtration step is poor, while 10 cm
Beyond the corner, it takes time to remove the ink.
The hot water in the treatment step for removing the ink must be alkaline, and the pH is preferably 9.0 or more. As a method for imparting alkalinity, NaOH, KO
Addition of H, ammonia or the like to hot water can be mentioned. The temperature of the cleaning liquid is preferably hot water of 50 to 100 ° C, and the higher the temperature, the higher the dropping efficiency. The amount of the label and the washing solution used is not uniform according to the size of the label, but it is necessary to use 5 to 20 times for a very large one and 0.2 to 5 times for a crushed small one. In addition, a circulation-type washing may be performed to improve efficiency. The washing time is preferably within 30 minutes in the recycling process. The ink shedding rate may be 90% or more, preferably 98%.
%, More preferably 99.9% or more.

The intermediate layer existing between the ink layer and the base material layer is dissolved (including finely dispersed) in alkaline hot water.
It is preferable to use a possible resin. The soluble resin is not particularly limited, but it is necessary that the resin has a hydrophilic group introduced therein so as to be able to swell or dissolve in alkaline hot water. Examples of the hydrophilic group include a hydroxyl group, a polyethylene glycol group, a carboxylic acid group, a carboxylic acid group, a sulfonic acid group, a sulfonic acid group, a phosphonic acid group, and a phosphonate group.

Examples of resins into which these hydrophilic groups are introduced include polyester resins, polyacrylic resins, acryl-modified polyester resins, polyurethane resins, and polyolefin resins. Preferred are polyester-based resins, acrylic-modified polyester resins, and acrylic-modified polyurethane resins. Examples of the acrylic-modified polyester resin include a method of using an acrylic macromonomer having two or more hydroxyl groups only at one end at the time of polyester synthesis, and a method of polymerizing the acrylic monomer in the presence of the polyester resin after synthesizing the polyester. A polyester obtained by grafting the acrylic polymer obtained by the method as a branch portion is mentioned as a preferable example. As the acrylic modified polyurethane resin, a method of using an acrylic macromonomer having two or more hydroxyl groups only at one end at the time of synthesizing polyurethane, a method of polymerizing the acrylic monomer in the presence of this polyurethane resin after synthesizing the polyurethane, etc. A preferable example is a polyurethane obtained by grafting the obtained acrylic polymer as a branch portion. As the polyol used here, a polyester polyol is preferable.

Although there is no particular limitation, a compound soluble in, for example, alkaline hot water may be added to these resins. The compounds soluble in the alkaline hot water are the same as the compounds contained in the above-described ink.

In consideration of the practicality as a label, it is necessary to prevent the ink layer from peeling off during normal use. For this reason, it is necessary to adjust the amount of the hydrophilic group or the compound soluble in the alkaline hot water in the ink and the intermediate layer. The bottle to which the label of the present invention has been attached can be attached by a conventional method so that the label at least covers the body. In the case of a heat-shrinkable label, the label can be heated so that the label can be in close contact with the body of the bottle.

Next, the bottle of the present invention to which the above-mentioned label is attached will be described. The bottle of the present invention is a bottle containing polyethylene terephthalate as a main component.
This is obtained by reacting terephthalic acid or its ester derivative with ethylene glycol. In this polyethylene terephthalate, other dicarboxylic acids (including ester derivatives) and / or other glycols may be copolymerized at a ratio of 40 mol% or less based on all dicarboxylic acids or all glycol components, respectively. Preferably, it is 20 mol% or less, more preferably 5 mol%.
It is as follows. Most preferably, it is polymerized only from terephthalic acid and ethylene glycol. Examples of dicarboxylic acids other than terephthalic acid include phthalic acid, isophthalic acid, aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, adipic acid, sebacic acid, azelaic acid, and fats such as decane dicarboxylic acid. And alicyclic dicarboxylic acids such as aliphatic dicarboxylic acids and cyclohexanedicarboxylic acids. Further, these ester derivatives may be used.

Examples of glycols other than ethylene glycol include aliphatic glycols such as diethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, and alicyclic glycols such as cyclohexanedimethanol. And aromatic diols such as bisphenols, hydroxone, and 2,2-bis (4-β-hydroxyethoxyphenyl) propane. The content of the cyclic trimer oligomer of ethylene terephthalate in the resin of the bottle equipped with the label of the present invention is 1.0% or less.
When the content of the ethylene terephthalate cyclic trimer oligomer exceeds 1.0%, the amount of the oligomer in the resin becomes too large in the step of re-pelleting the bottle, although the latter will be performed later.
The amount of cyclic trimer oligomers in the resulting regenerated pellets also increased, and when the regenerated pellets were used for spinning, extrusion molding, injection molding, etc., they adhered to dies and nozzles, etc. Often adheres to the surface, deteriorating the quality of the product.

In order to obtain a bottle in which the content of the ethylene terephthalate cyclic trimer oligomer is 1.0% or less, the amount of the cyclic trimer oligomer in the resin forming the bottle itself must be 1.0% or less. is necessary. Hereinafter, the method for producing the polyester will be described with reference to the case of polyethylene terephthalate as an example.
A method for obtaining a resin of not more than% by weight will be exemplified.

Each raw material is subjected to esterification in the presence of an esterification catalyst, then to liquid phase polymerization in the presence of a polymerization catalyst, and then to solid phase polymerization if necessary. As a method for producing polyethylene terephthalate, there are a batch method and a continuous method, and an example of a preferable production method in the continuous method will be described below.

First, 1.02 to 1.4 mol, preferably 1.03 to 1.0 mol per mol of terephthalic acid or its ester derivative.
A slurry containing 3 moles of ethylene glycol is prepared and continuously supplied to the esterification reaction step.

The esterification reaction is carried out using a multistage apparatus in which at least two esterification reactors are connected in series, and under conditions where ethylene glycol is refluxed, water or alcohol produced by the reaction is removed outside the system by a rectification column. Perform while removing. The temperature of the first stage esterification reaction is 240-27.
0 ° C., preferably 245-265 ° C., and the pressure is 0.2-3 kg / cm ² G, preferably 0.5-2 kg / cm ² . The temperature of the final esterification reaction is usually 250 to 280 ° C, preferably 255 to 275 ° C.
The pressure is usually 0 to 1.5 kg / cm ² G, preferably 0 to 1.3 k
g / cm ² G. When the reaction is carried out in three or more stages, the reaction conditions for the intermediate stage esterification reaction are those between the above-mentioned first-stage reaction conditions and final-stage reaction conditions. The increase in the conversion of these esterification reactions is preferably distributed smoothly at each stage. Finally, it is desirable that the esterification reaction rate reaches 90% or more, preferably 93% or more. These esterification steps result in a molecular weight of 500
A low order condensate of about 5000 is obtained.

When terephthalic acid is used as a raw material, the above esterification reaction can be carried out without a catalyst by the catalytic action of terephthalic acid as an acid, but may be carried out in the presence of a polycondensation catalyst. In particular, when dimethyl terephthalate is used as a raw material, Zn, Cd, Mn, C
o, Ca, Ba and other fatty acid salts, carbonates, metallic Mg and P
When b, Zn, Sb, Ge oxide, or the like is used, the reaction can be accelerated. Tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine; tetraethylammonium hydroxide;
When a small amount of quaternary ammonium hydroxide such as butylammonium and trimethylbenzylammonium hydroxide and a basic compound such as lithium carbonate, sodium carbonate, potassium carbonate and sodium acetate are added, the dimer in the main chain of polyethylene terephthalate is reduced. This is preferable because the ratio of the oxyethylene terephthalate component unit can be maintained at a relatively low level.

Next, the obtained low-order condensate is supplied to a multi-stage liquid phase condensation polymerization step. The polycondensation reaction conditions are such that the reaction temperature of the first stage polycondensation is 250 to 290 ° C., preferably 260 to 290 ° C.
~ 280 ° C and a pressure of 500-20 Torr, preferably 200
~ 30 Torr, the final stage polycondensation reaction temperature is 265 ~ 300
° C, preferably 275-295 ° C, pressure 10-0.1 Torr
r, preferably 5 to 0.5 Torr. When the reaction is carried out in three or more stages, the reaction conditions for the polycondensation reaction in the intermediate stage are those between the above-mentioned first-stage reaction conditions and the last-stage reaction conditions. It is preferred that the degree of intrinsic viscosity (IV) increase achieved in each of these polycondensation reaction steps be distributed smoothly. The intrinsic viscosity (IV) of the thus obtained polyethylene terephthalate after liquid phase polymerization is usually 0.1.
The range is 35 to 0.80 dl / g, preferably 0.45 to 0.75 dl / g, and more preferably 0.55 to 0.75 dl / g.

The polycondensation reaction uses a polycondensation catalyst. As the catalyst, germanium compounds such as germanium dioxide, germanium tetraethoxide, and germanium tetra n-butoxide, antimony catalysts such as antimony trioxide, and titanium catalysts such as titanium tetrabutoxide are preferable. Among these catalysts, a germanium dioxide compound is preferable in terms of hue and transparency, and antimony trioxide is preferable in consideration of fast crystallinity and cost. The amount of the catalyst is 0.0005 to 0.2% by weight, preferably 0.00
01-0.1% by weight.

The polycondensation reaction includes phosphoric esters such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, triphenyl phosphite, trisdodecyl phosphite, and the like. Phosphites such as trisnonyl phenyl phosphite, acid phosphates such as methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate and phosphoric acid, polyphosphoric acid, etc. Is preferably added as a stabilizer. The amount of the stabilizer is 0.001 to 0.1 in terms of the weight of elemental phosphorus based on all the starting materials.
% By weight, preferably 0.002 to 0.02% by weight. The catalyst and the stabilizer may be added during the esterification reaction step or during the polycondensation reaction step.

The polyethylene terephthalate obtained in the liquid phase polycondensation step is extruded, cut, and formed into pellets of 2 to 4 mm. The pellets thus obtained usually have a density of 1.33 to 1.36 g / cm ³ and an intrinsic viscosity of 0.4 to
0.75, the content of diethylene glycol is 1.0 to 4.0 mol%, the content of acetaldehyde is 5 to 100 ppm, the content of the cyclic trimer oligomer is 0.5 to 4.0% by weight, the glass transition point is 50 to 80 ° C, and the melting point is 240 to 280. ° C at elevated crystallization temperature
130-180 ° C.

In order to reduce the content of the cyclic trimer oligomer to 1.0% or less, the above-mentioned polymerization conditions, the amounts of catalysts and stabilizers, the conditions of the extruder for pelletizing, and the like should be lowered. This can be used for a bottle equipped with the label of the present invention, but in order to further reduce the amount of oligomer, it is preferable to subject the obtained pellet to solid phase polymerization. Although the polymerization of polyester has been described in detail with respect to the continuous system, even in the batch system, the esterification reaction and polycondensation reaction conditions can be changed in the latter half of the reaction as in the continuous system to obtain polyethylene terephthalate.

The pellets supplied to the solid-state polymerization step are first dried in a dry state, preferably under an inert gas atmosphere, for 120 to 120 hours.
Crystallize by treating at 200 ° C for 10 minutes to 4 hours. In this step, the pellets may be subjected to steam or an inert atmosphere containing steam in order to effectively reduce the amount of acetaldehyde. The solid-phase polymerization of the pre-crystallized pellets is carried out at a temperature of 190 to 230 ° C., preferably 195 to 225 ° C., a pressure of 1 kg / cm ² G to 10 Torr, preferably normal pressure and 100 Torr, under nitrogen gas or the like. This is performed while blowing an inert gas. This solid-phase polymerization may be performed in one stage or in multiple stages.

By performing solid phase polymerization, the amount of cyclic trimer oligomer can be reduced to 1.0 to 0.2 wt%. The intrinsic viscosity is preferably 0.70 dl / g or more, and more preferably 0.72 dl / g or more. The resin after solid-phase polymerization usually has a density of 1.37 to 1.43 g / cm ³ , an intrinsic viscosity of 0.7 to 1.4, a diethylene glycol content of 1.0 to 4.0 mol%, an acetaldehyde content of 10 ppm or less, and a glass transition point of 50 to 80
° C, melting point 240-280 ° C, 130-180 at elevated crystallization temperature
Degrees Celsius.

It is preferable to deactivate the polycondensation catalyst because the increase in the amount of the cyclic trimer oligomer can be reduced when the bottle is regenerated into pellets. The catalyst is deactivated by subjecting polyethylene terephthalate pellets to water treatment or steam treatment. The water treatment of the pellets is carried out by immersing the pellets in water at 40 to 120 ° C, preferably 50 to 100 ° C, for 5 minutes to 10 hours, preferably for 10 minutes to 5 hours. As the water, distilled water, ion-exchanged water or the like is used. Further, in order to shorten the processing time, hydrochloric acid, phosphoric acid or the like can be added. The pellets are subjected to steam treatment by blowing steam or steam-containing gas or steam-containing air at 40 to 120 ° C., preferably 50 to 110 ° C., into the pellets for 20 minutes to 20 hours, preferably 1 hour to 10 hours.

When the pellets are subjected to water treatment or steam treatment in a continuous manner, the pellets are continuously charged from above into a tower-type treatment device, and water or steam is continuously supplied in parallel or countercurrent. Further, it can be performed in a batch system. Thereafter, in the case of water treatment, the granular polyethylene terephthalate is drained and dried. In the case of steam treatment, it can be directly transferred to a drying step. For drying, a commonly used drying treatment of polyethylene terephthalate can be used. As a method for continuous drying, granular polyethylene terephthalate is supplied from the upper portion of the hopper, and a drying gas is passed from the lower portion. A rotating disk type heating type continuous dryer is also preferable. It can also be dried in a batch mode by a double cone type rotary dryer or the like.

It is effective to carry out the catalyst deactivation treatment with pellets after solid-phase polymerization, but pellets after liquid-phase polymerization may be performed. When the active treatment is performed, there is a problem that the degree of polymerization hardly increases when the solid phase polymerization is performed thereafter. Polyethylene terephthalate using germanium dioxide as a polycondensation catalyst is preferable because the catalyst can be easily deactivated.

Although the method for producing the resin used in the bottle of the present invention has been described using polyethylene terephthalate as an example, the polyester resin used in the bottle of the present invention is substantially the same as described above even if it is a copolymerized polyester. The method can be used. The polyester chip obtained as above is molded into a preform called parison using an extruder, and the preform is blown with an inert gas or dry air and blow-molded to form a hollow molded bottle of the present invention. And

The molding conditions for the preform are as follows: the pellets are dried to a moisture content of 0.05% or less, preferably 0.02% or less, more preferably 0.01% or less, and most preferably 0.005% or less. throw into. The cylinder temperature of the injection molding machine is 260 ~ 310 on the hopper side.
℃, 250-300 ℃ in the middle of the cylinder, 240 on the nozzle side
~ 295C is preferred. The mold temperature is preferably 5 to 100 ° C. The average residence time of the injection molding machine is 10 to 200 seconds, preferably 20 to 180 seconds, more preferably 30 to 150 seconds.
If the temperature of the injection molding machine is too high or the residence time is too long, the amount of oligomers increases, the intrinsic viscosity decreases, the amount of acetaldehyde increases, and the coloration due to decomposition of the resin is undesirable. The preform obtained in this way is hot parison method in which the blow molding is continued while it is still warm, or once cooled, the polyform is stored, and the preform is again heated to about 70 to 140 ° C. before blow molding. It is molded as a hollow molded bottle by the cold parison method of performing blow molding.

The stretching ratio at this time is 1.5 to 1 in the circumferential direction.
0, more preferably 2 to 6 times, 1.3 to 8 in the axial direction,
More preferably, it is 1.5 to 5 times. The area ratio is 3 to 3
It is preferably 0, more preferably 5 to 20 times. Hollow molded bottles
After blow molding, heat setting can be performed in a mold at about 120 to 170 ° C. to increase heat resistance. It is also preferable to heat the plug portion to about 130 to 200 ° C. before or after blow molding to crystallize the plug portion in order to prevent deformation of the plug portion. Even in blow molding, if the reheating temperature or mold temperature is too high, or if the reheating time or heat setting time is too long, the oligomer amount will increase, the intrinsic viscosity will decrease, the acetaldehyde will increase, and the coloring will occur due to the decomposition of the resin. It is unfavorable.

The bottle of the present invention is a hollow molded bottle molded as described above, and the content of the cyclic trimer oligomer of ethylene terephthalate is 1.0% by weight or less.
The content of the cyclic trimer oligomer is preferably 0.7% by weight or less, more preferably 0.6% by weight or less, further preferably 0.5% by weight or less, and most preferably 0.5% by weight.
It is as follows. If the content exceeds 1.0% by weight, the bottle is collected, and the label is not removed.
Oligomers increased, spinning using regenerated pellets,
When performing extrusion molding, injection molding, or the like, the cyclic trimer oligomer often adheres to a mold, a nozzle, or the like, or adheres to the product itself, thus deteriorating the quality of the product.

It is preferable that the condensation polymerization catalyst of the present invention has been deactivated. The deactivation of the catalyst can significantly reduce the amount of cyclic trimer oligomer produced when producing regenerated pellets.

The fact that the catalyst has been deactivated can be determined by measuring the solid-state polymerization rate. The method for measuring the solid-state polymerization rate can be performed as follows. Approximately 5 bottle body
cut into 3/4 inch stainless steel pipes with a length of about 10 cm (both ends are threaded for pipe connection), and the both ends of the resin part are made of glass wool. Cover it so that it does not move inside. Elbow type pipe at both ends of this pipe, 1/2 inch pipe 20
cm so that the pipe filled with the sample is placed at the bottom of the U-shape. Six pipes in which such a sample is set are prepared. These U-shaped sample-containing pipes are
15c in silicon bath controlled at 10 ± 1 ℃
m Submerged (with the top end of the pipe exposed from the liquid level), and dry nitrogen (dew point -50 ° C or less, oxygen concentration 20 ppm or less) heated to 210 ° C from one of the top ends of the pipe at a flow rate of 5 ml / min. Inhale. The silicon bath is sufficiently stirred so that the temperature is uniform and there is no temperature distribution. Three of these pipes are taken out of the oil bath after 2 hours and immediately immersed in water at 25 ° C. for cooling. The other three are subjected to a solid-phase polycondensation reaction as they are, taken out after another 15 hours, and cooled similarly. The intrinsic viscosity of the sample in each pipe is measured, and the solid-state polymerization rate is calculated from (average intrinsic viscosity of sample after 15 hours treatment + average intrinsic viscosity of sample after 2 hours treatment) / 13.

The solid-state polymerization rate measured in this way is 0.
It is considered that the catalyst is deactivated if it is less than 0050 dl / g · hr. Preferred solid-state polymerization rate is 0.0040 dl / ghr or less, particularly preferably 0.0035 dl / ghr or less, most preferably 0.00
30 dl / g · hr. The solid-state polymerization rate when the catalyst has not been deactivated is usually 0.006 to 0.03 dl / g · hr.

Further, the bottle of the present invention has, as other characteristics, an intrinsic viscosity of 0.4 to 1.4 dl / g, and more preferably 0.7 to 1.4 dl / g.
dl / g is preferred and the content of diethylene glycol is 1.
The content is preferably 0 to 4.0 mol%, more preferably 1.0 to 3.0 mol%, and the content of acetaldehyde is preferably 40 ppm or less, more preferably 30 ppm or less. In addition, when the bottle is made of polyethylene terephthalate, the density of the body further increases to 1.
33~1.43g / cm ^3, more preferably from 1.37~1.41g / cm ^3, a glass transition temperature 50 to 80 ° C., a melting point 240 to 280 ° C., 130 to 180 ° C. at a heating crystallization temperature is preferred.

The bottle obtained as described above is filled with the contents, and further has an ink layer which can be removed in alkaline hot water on at least one side of the thermoplastic polymer film, and the ink is removed in alkaline hot water. A label in which an intermediate layer exists between the ink layer and the base material layer is attached, and the bottle according to the embodiment of the present invention is obtained. The bottle equipped with the label of the present invention is collected after the use as a bottle is completed, and is typically crushed after washing the bottle, and then the ink layer is removed in alkaline hot water, followed by washing with water. Dry and optionally wind select to obtain mixed flakes of bottle and label. This can be regenerated into regenerated pellets by an extruder and used.

In the extrusion regenerated pelletization, the mixed flakes are usually fed from a hopper using an extruder,
For polyethylene terephthalate, cylinder temperature 2
It is extruded from a nozzle at about 60 to 320 ° C. and cut into regenerated pellets.

The regenerated pellets using the bottle of the present invention
The content of the cyclic trimer oligomer is low, and when spinning, extrusion molding, injection molding, etc. are performed, the cyclic trimer oligomer does not adhere to molds and nozzles, and adheres to the product itself, and high quality. Fibers, films and molded products are obtained. In addition, since oligomers such as molds and nozzles are less attached, cleaning is less frequent, and productivity can be greatly improved as compared with the case where recycled pellets obtained from a conventional bottle are used.

[0077]

EXAMPLES Conditions for measuring resin properties 1) Cyclic trimer oligomer A sample cut from the bottle body was dissolved in a mixed solution of hexafluoroisopropanol / chloroform, and further diluted with chloroform. After adding methanol to precipitate a polymer, the mixture is filtered. The filtrate was evaporated to dryness, made up to volume with dimethylformamide, and quantified by liquid chromatography.

2) Intrinsic Viscosity Using a sample cut from the body of the bottle, 1,1,2,2
-Determined from the solution viscosity at 30 ° C in a mixed solvent of tetrachloroethane / phenol (2: 3 weight ratio).

3) Diethylene glycol content A sample cut from the bottle body was decomposed with methanol, and the amount of DEG was determined by gas chromatography.
It was expressed as a ratio (mol%) to the total glycol components.

4) Acetaldehyde content Sample cut from bottle body / distilled water = 1 g / 2 ml
Into a glass ampoule purged with nitrogen and seal the top,
Extraction treatment was performed at 160 ° C. for 2 hours. After cooling, acetaldehyde in the extract was measured by high-sensitivity gas chromatography, and the concentration was expressed in ppm.

5) Density The body of the bottle was cut into about 1 cm squares, and carbon tetrachloride / n
-Measured at 25 ° C with a density gradient tube of a heptane mixed solvent.

6) Glass transition point, melting point, elevated temperature crystallization temperature Measured using a differential scanning calorimeter (DSC). First,
Dry at 140 ° C and 10 Torr or less for 5 hours.
The mmg slice was pressed and sealed in an aluminum pan under a nitrogen atmosphere. Set this sample on DSC, 100 ℃
The temperature was raised at 290 ° C./min or more and kept at 290 ° C. for 10 minutes. Blow liquid nitrogen and cool rapidly to below -20 ℃, then 10 ℃
/ Min was measured at a heating rate. In each case, the peak temperature was shown.

Production Example of Polyester Resin A stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser was charged with 460 g of dimethyl terephthalate, 460 g of dimethyl isophthalate, and fumaric acid.
29 g, ethylene glycol 341 g, 3-methylpentanediol 650 g and tetra-n-butyl titanate 0.1 g.
52 g was charged, and a transesterification reaction was performed at 160 to 220 ° C. over 4 hours. Then the temperature was raised to 250 ° C,
After the pressure of the reaction system was gradually reduced,
The reaction was carried out for 30 minutes to obtain a polyester resin. The obtained polyester resin A was pale yellow and transparent.

Production Example of Acrylic-Modified Polyester Resin A polyester flask obtained by the method shown in the Production Example of Polyester Resin in a glass flask equipped with a stirrer, a thermometer and a reflux condenser was added with 5 mol% of fumaric acid in the acid component. 75 g of the copolymerized polyester resin, 56 g of methyl ethyl ketone, and 19 g of isopropyl alcohol were charged and heated and stirred to dissolve the resin. A solution in which 17.5 g of methacrylic acid, 7.5 g of ethyl acrylate and 1.2 g of azobisdimethylvaleronitrile were dissolved in 10 g of methyl ethyl ketone was added dropwise to the dissolved resin at a constant rate.
The mixture was further stirred for 3 hours. Thereafter, 300 g of water and 25 parts of triethylamine were added to the reaction solution, and the mixture was further stirred for 1 hour. Next, the temperature of the solution was raised to 100 ° C., and methyl ethyl ketone, isopropyl alcohol, and excess triethylamine were distilled off by distillation to obtain an acrylic-modified polyester resin. Example of manufacturing a label A polyester film having a thickness of 50 μm (a heat shrinkage rate of 72% in a circumferential direction after label processing: S manufactured by Toyobo Co., Ltd.)
5630), the above-mentioned acrylic-modified polyester resin is applied, dried at 60 ° C., and a 0.1 μm intermediate layer is laminated. On this intermediate layer, shrink EX (manufactured by Toyo Ink Co., Ltd.) is used as an ink which can be removed in alkaline hot water. The ink to which 1.0% by weight of ethylene glycol monobutyl ether (after drying) was added was solid-printed by gravure printing in order of green, gold, and white, and dried in an oven at 60 ° C. The thickness of the ink layer was 10 μm in total. Using a solvent, the printed film was subjected to adhesive processing into a tube shape with a maximum outer periphery of the bottle + 20 mm, and cut to produce a label having a width of 12 cm.

Example A 2 liter bottle was formed using polyethylene terephthalate inactivated by a water treatment with an oligomer amount of 0.35% by weight and an intrinsic viscosity of 0.8. Oligomer content of bottle body is 0.37% by weight, intrinsic viscosity 0.75, acetaldehyde content 5ppm, DEG content 2.0mol%, solid-state polymerization rate 0.00
27dl / g · hr, glass transition temperature 77 ° C, melting point 255 ° C, elevated crystallization temperature 145 ° C. After attaching a label to the bottle, the bottle was cut into about 1 cm squares with a shredder to form flakes. This was immersed in a 3% aqueous sodium hydroxide solution at 95 ° C. with stirring for 30 minutes. The ink was completely removed from the label. The flakes were lifted, washed three times with water, and dried under a nitrogen atmosphere at 140 ° C. and 5 torr for 5 hours. The flakes were repelletized using a 30 mmφ twin screw extruder (manufactured by Ikegai Iron and Steel Co., Ltd.). Cylinder temperature is 290 ° C Average residence time is 1
50 seconds. Regenerated pellet oligomer content is 0.39
% By weight.

Comparative Example Germanium-catalyzed polyethylene terephthalate having an oligomer content of 0.9% by weight and an intrinsic viscosity of 0.56 (without deactivation of the catalyst)
(The amount of oligomer in the body of the bottle is
1.2% by weight, intrinsic viscosity 0.54, acetaldehyde amount 25ppm
, DEG content 2.0mol%, solid-state polymerization rate 0.009dl / g
Regenerated pellets were obtained in the same manner as in Example 1 except that the glass transition temperature was 76 ° C., the melting point was 253 ° C., and the crystallization temperature was 155 ° C.). The oligomer content of the regenerated pellet is 1.
It was 5% by weight.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a step of recovering a thermoplastic polymer as a pellet from a labeled bottle of the present invention.

FIG. 2 is a diagram illustrating an example of a process of recovering a thermoplastic polymer as pellets from a conventional bottle with a label.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 7/00 B65D 1/00 A // B29K 67:00 105: 26 B29L 22:00 (72) Inventor Haruo Asai 2-1-1 Katata, Otsu City, Shiga Prefecture F-Term in Toyobo Co., Ltd. Research Laboratory 3E033 AA01 BA17 BA18 BB08 CA03 CA06 CA18 EA09 EA12 FA03 4F073 AA23 AA32 BA23 BB03 EA03 EA11 EA41 4F201 AD20 AG AH55 AK01 BA05 BA07 BC01 BC02 BC12 BC25 BC29 BC37 BD06 BP10 BP15 BP20 BP31 BR02 BR10 BR31 4F208 AA24 AD05 AD09 AD20 AG07 AH55 AK01 LA05 LB01 LB19 LW02 LW10 LW31 LW45

Claims (5)

[Claims] At least one surface of a thermoplastic polymer film has an ink layer that can be removed in alkaline hot water, and an intermediate layer that removes ink in alkaline hot water exists between the ink layer and the substrate layer. A hollow molded bottle made of a polyester resin to which a label to be attached is attached, wherein the content of a cyclic trimer oligomer of ethylene terephthalate in the resin of the bottle is 1.0% or less. . 2. The hollow molded bottle according to claim 2, wherein the condensation polymerization catalyst of the resin of the bottle is deactivated. 3. A method for removing an ink, comprising: immersing a bottle equipped with the label according to claim 1 in alkaline hot water to remove an ink layer on the label from the label. 4. A method for regenerating a bottle with a label, wherein the label from which the ink layer has been removed by the method according to claim 3 is melted together with the bottle to which the label is attached, and regenerated. 5. A regenerated pellet obtained by the method according to claim 4.