JP2001055215A - Resin bottle with label stuck thereon, and its recycling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recycled pellet which is excellent in crystallinity, and free from any degradation of the strength, disagreeable odor or coloring by specifying the limiting viscosity number of a resin of a bottle with a label stuck thereon having an ink layer which can be removed in an alkaline hot water on one side of a thermoplastic resin polymer film to allow the bottle to be pulverized with the label stuck thereon. SOLUTION: The resin of this polyester resin bottle mainly consists of a polyethylene terephthalate, and is 0.60-1.0 dl/g in limiting viscosity number. The bottle with a label consisting of this resin stuck thereon is recovered after the use for the bottle is terminated, and after the bottle is cleaned, the bottle is pulverized, and an ink layer is removed in an alkaline hot water, the bottle is cleaned in water, and dried, wind-selected to obtain the mixed flake of the bottle and the label. The flake is recycled into a recycled pellet by an extruder. The recycled pellet using this bottle is less in coloring or disagreeable odor, and a fiber, a film and a formed article of high quality can be obtained. Its strength is also high, and the pellet can be used for extensive applications.

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.

According to this method, the recovery bottle can be easily regenerated into pellets, and the problem of coloring derived from the ink of the label is eliminated. However, the strength of the obtained regenerated pellets is still insufficient, and the resin is colored. Occurs,
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. In addition, it is an object of the present invention to provide a labeled resin bottle which does not cause coloring of the pellets in the regenerating step and can obtain regenerated pellets having high strength.

[0009]

That is, the present invention relates to a hollow molded bottle made of a polyester resin having a label attached to at least one surface of a thermoplastic polymer film and having an ink layer removable in alkaline hot water. A hollow molded bottle characterized in that the intrinsic viscosity of the resin of the bottle is 0.60 to 1.0 dl / g.

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. In order for the ink layer to be removable in hot alkaline water, the ink itself must be soluble or dispersible with alkali, or be swellable or soluble (including dispersion) with alkali between the ink layer and the label film layer.
This can be achieved by providing a possible intermediate layer.

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

[0012] In the label, the heat-shrinkable film may be a polyester-based heat-shrinkable film.

The label may have a heat shrinkage rate of the polyester heat shrinkable film of 30 to 80%. Here, the heat shrinkage is a shrinkage measured by immersion in hot water at 95 ° C. for 10 seconds.

The label may contain a compound whose ink layer swells or is soluble in alkaline hot water.

[0015] The bottle is characterized by having the label attached thereto.

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

In the bottle of the present invention having the above-described structure, after the ink layer is easily removed, the bottle and the label can be simultaneously subjected to a collecting step and reused.

[0018] The bottle may have a heat shrinkage of the attached label in the bottle circumferential direction of 0.1% or more and less than 80%.

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

[0020] In addition, the ink removing method includes the steps of:
It is characterized in that the ink layer on the label is removed by dipping in alkaline hot water.

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

Further, the ink removing method is characterized in that the bottle with the label attached thereto is immersed in alkaline hot water to remove the ink layer on the label.

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

A method of recycling a bottle with a label is characterized in that the label from which the ink layer has been removed by the above method is melted together with the bottle to which the label is attached, and then recycled.

In the method of recycling a bottle with a label having the above structure, a label and a bottle having no ink layer can be directly recycled to the collecting 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 substantially containing ink and which 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 is a hollow molded bottle made of a polyester resin in which a label having an ink layer which can be removed in alkaline hot water is attached to at least one surface of a thermoplastic polymer film. First, a label having an ink layer that can be removed in alkaline hot water on at least one surface of a thermoplastic polymer film 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 due to the heat shrinkage of the film in the washing step and 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.

The 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 calendering method is stretched in one direction by 2.5 times to 7.0 times, preferably 3.0 times 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 of the heat-shrinkable film in the main shrinkage direction is about 30 to 80%, but when the heat-shrinkable film is 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 the shrinkable film used in the label used in the bottle equipped with the label of the present invention, not only the above 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 surface orientation coefficient of the thus obtained film is preferably 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.
In addition, an intermediate layer that can swell or dissolve in alkaline hot water is provided between the ink layer and the base film even with ordinary ink, and the ink layer can be removed by swelling or dissolving the intermediate layer. It can also be. 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-mentioned 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 such as pigments or dyes, A method in which a binder and a volatile organic solvent are added to an ink containing the constituents is exemplified. Examples of the compound 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 in 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 a 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 it 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 depending on 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.

For the intermediate layer between the ink layer and the base material layer, it is preferable to use a resin used in alkaline hot water and swellable or soluble in alkaline hot water. The swellable or soluble resin is not particularly limited as long as it has a function of removing the ink layer, but a hydrophilic group is introduced into the resin so that the resin can swell or dissolve in alkaline hot water. It is necessary to be. 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 or swellable in alkaline hot water can be added to these resins. The compounds soluble or swellable 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 and the soluble or swellable compound in the alkaline hot water for the ink and the intermediate layer. The bottle equipped with the label of the present invention,
In a conventional manner, the label can be attached so as to bite at least 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 intrinsic viscosity of the resin of the polyester resin bottle provided with the label of the present invention must be 0.60 to 1.0 dl / g. The intrinsic viscosity is more preferably 0.
It is 65 to 0.95 dl / g, particularly preferably 0.68 to 0.90 dl / g, and most preferably 0.70 to 0.90 dl / g. 1.0dl / intrinsic viscosity
If it exceeds g, the viscosity in the pellet regenerating step is too high, so a high temperature is required or the temperature becomes high due to heat generation in a row, and the obtained regenerated pellet is colored or aldehydes generated by decomposition of the resin. Smell due to acids is strong. On the other hand, when the intrinsic viscosity is less than 0.6 dl / g, the intrinsic viscosity of the regenerated pellets becomes too low, and sufficient strength cannot be obtained.

The acid value of the resin of the polyester resin bottle equipped with the label of the present invention is 5 to 50 equivalents / ton.
More preferably, more preferably 7 to 45 equivalents / to
n, more preferably 10 to 40 equivalents / ton.
If the acid value is below the above range, the amount of aldehyde generated during re-pelleting will be too large, and the resulting regenerated pellets may have an unpleasant odor. In addition, when the content is more than the above range, the decrease in the molecular weight of the polyester resin at the time of the regenerated pellet may be large.

Next, a method for obtaining a polyester resin and a bottle will be described. 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 1.3 mol per mol of terephthalic acid or its ester derivative.
A slurry containing 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 in which ethylene glycol is refluxed, water or alcohol produced by the reaction is removed from the system by a rectification column. Perform while removing. The temperature of the first stage esterification reaction is 240-270.
C., preferably 245-265.degree. C., and pressure is 150-2200 torr, preferably 300-1500 torr. The temperature of the final esterification reaction is usually 250 to 280 ° C, preferably 255 to 275 ° C,
The pressure is usually from 0 to 1100 torr, preferably from 0 to 900 torr. 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. It is preferable that the increase in the conversion of these esterification reactions is smoothly distributed at each stage. Eventually, the esterification reaction rate
It is desirable to reach at least 90%, preferably at least 93%. By these esterification steps, a low-order condensate having a molecular weight of about 500 to 5,000 can be 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 from 250 to 290 ° C., preferably from 260 to 2
80 ° C. and pressure is 500-20 Torr, preferably 200-30 To
In rr, the temperature of the final stage polycondensation reaction is 265-300C, preferably 275-295C, and the pressure is 10-0.1 Torr, preferably 5-0.5 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 0.35 to 0.80 dl.
/ g, preferably 0.45-0.75 dl / g, more preferably 0.55
It is in the range of ~ 0.75dl / 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 0.001 to
~ 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% by weight, preferably 0.002 to 0.02% by weight, as the weight of elemental phosphorus based on all the starting materials. 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 / cm3 and an intrinsic viscosity of 0.4 to 0.7.
5, the content of diethylene glycol is 1.0 to 4.0 mol%,
Acetaldehyde content is 5 to 100 ppm, cyclic trimer oligomer content is 0.5 to 4.0% by weight, glass transition point 50
~ 80 ° C, melting point 240 ~ 280 ° C, 130 ~ 180 at elevated crystallization temperature
Degrees Celsius.

The intrinsic viscosity may be increased to 0.6 dl / g or more by this liquid phase polymerization, and this resin may be used for bottle molding. However, in order to effectively increase the molecular weight and decrease the oligomer amount and the acetaldehyde amount, , Resin with relatively low intrinsic viscosity (0.
(About 6 dl / g) is preferably subjected 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 phase polymerization step are first dried in a dry state, preferably under an inert gas atmosphere, for 120 to 2 hours.
Treat at 00 ° C for 10 minutes to 4 hours to crystallize. In this step, the chip may be subjected to steam or an inert atmosphere containing steam in order to effectively reduce the amount of acetaldehyde. Solid phase polymerization of pre-crystallized pellets
Temperature is 190 ~ 230 ° C, preferably 195 ~ 225 ° C, pressure is 760
It is carried out under a condition of up to 10 Torr, preferably 760 to 100 Torr, while blowing an inert gas such as nitrogen 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 / cm3, an intrinsic viscosity of 0.7 to 1.1, 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, and elevated crystallization temperature 130-180 ° C.

The polyester pellets can be subjected to a catalyst deactivation treatment in order to prevent contamination of the mold during molding. The catalyst is deactivated by subjecting polyethylene terephthalate pellets to water treatment or steam treatment.
The water treatment of the pellets is performed 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. Steam treatment of the pellets is carried out 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.

Polyethylene terephthalate using germanium dioxide as a polycondensation catalyst is preferred 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 of the preform are as follows: the moisture content of the pellets is dried to 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 preferably about 260 to 310 ° C on the hopper side, about 250 to 300 ° C in the middle of the cylinder, and about 240 to 295 ° C on the nozzle side. The mold temperature is preferably 5 to 100 ° C. The average residence time of the injection molding machine is 10-200 seconds, preferably 20-180
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 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.
It is preferably 0, more preferably 2 to 6 times, 1.3 to 8 in the axial direction, and more preferably 1.5 to 5 times. Further, the area ratio is preferably 3 to 30, more preferably 5 to 20 times. The blow-molded bottle can be heat-set in a mold at about 120 to 170 ° C. after blow molding to increase heat resistance. Further, 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 amount of oligomers will increase, the intrinsic viscosity will decrease due to decomposition of the resin, acetaldehyde will increase, and coloring will occur. It is unfavorable.

The bottle of the present invention is a hollow molded bottle made of a polyester resin molded as described above, and the intrinsic viscosity of the resin of the bottle is 0.60 to 1.0 dl / g.

The bottle of the present invention has another resin characteristic in which the content of diethylene glycol is 1.0 to 1.0.
4.0 mol%, more preferably 1.0 to 3.0 mol%, the content of acetaldehyde is 40 ppm or less, further 30 ppm
The following is preferred. When the bottle is made of polyethylene terephthalate, the content of the cyclic trimer of ethylene terephthalate is 1% or less, and the density of the body is 1.
The glass transition point is preferably from 33 to 1.43 g / cm3, more preferably from 1.37 to 1.41 g / cm3, and the glass transition point is preferably from 50 to 80C, the melting point is from 240 to 280C, and the crystallization temperature is from 160 to 180C.

The bottle obtained as described above is filled with the contents, and is further provided with a label having an ink layer that can be removed in alkaline hot water, to provide a bottle according to the present invention. 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.

For 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
High quality fibers, films and molded products with little coloring and odor. In addition, it has high strength and can be used for a wide range of applications.

[0074]

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 body of the bottle 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 an approximately 1 cm square, 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, it was dried at 140 ° C. and 10 Torr or less for 5 hours, and a thin piece of about 10 mm was sealed in an aluminum pan under a nitrogen atmosphere and sealed. The sample was set in a DSC, heated at a rate of 100 ° C./min or more, and melted and held at 290 ° C. for 10 minutes. Liquid nitrogen was blown in to rapidly cool to -20 ° C or less, and then measured at a rate of 10 ° C / min. In each case, the peak temperature was shown. 7) Acid value (AV) About 0.5 g of a sample cut from the body of the bottle is dissolved in 20 ml of benzyl alcohol, and chloroform is added for dilution. AV was determined by a titration method using a 1 / 50N aqueous potassium hydroxide solution. Phenol red was used as an indicator.

8) Co-b value Co-b value was measured as follows using a color difference meter TC1500MC88 manufactured by Tokyo Denshoku. Chips or samples cut into chips of about 2 mm square were arranged in a glass cell with the glossy surface facing down, and put into the cell for 8 minutes. Shake the cell more lightly,
After packing tightly, resin was added until the lid was formed, and the lid was closed. The cell filled with the resin was placed on a sample table and measured. The measurement is performed by turning about 120 degrees each time the cell is measured once.
The measurement was performed twice, that is, at 120 degrees in three directions, and the average was obtained.

Production Example of Acrylic-Modified Polyester Resin A polyester flask obtained by the method described in the Production Example of Polyester Resin in a glass flask equipped with a stirrer, a thermometer and a reflux condenser was added 5% by mole 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, and 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.

Production Example A of a Label Removable in Alkaline Hot Water A polyester film having a thickness of 50 μm (heat shrinkage of 72% in the circumferential direction after label processing: S manufactured by Toyobo Co., Ltd.)
5630), the above acrylic-modified polyester resin is applied, dried at 60 ° C., a 0.1 μm intermediate layer is laminated, and green, gold, and white of Shrink EX (manufactured by Toyo Ink Co., Ltd.) are sequentially applied as an ink on the intermediate layer. Solid printing was performed by gravure printing, and drying was performed 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 having a maximum outer circumference of the bottle + 20 mm, and cut to produce a label A having a width of 12 cm.

Production Example B of Label Removable in Alkaline Hot Water Inks of each color were prepared by adding 1.0% by weight (after drying) of ethylene glycol monobutyl ether to Shrink EX (manufactured by Toyo Ink). A polyester heat-shrinkable film having a thickness of 50 μm (heat shrinkage in the circumferential direction after label processing: 72%: S5630 manufactured by Toyobo Co., Ltd.)
Solid printing was performed on the white by gravure printing in order, and drying was performed 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 having a maximum outer periphery of the bottle + 20 mm, and cut to produce a label B having a width of 12 cm.

Example 1 A bottle was formed using polyethylene terephthalate inactivated by a germanium catalyst deactivated by water treatment with an intrinsic viscosity of 0.77 dl / g. Oligomer content of bottle body is 0.32% by weight, intrinsic viscosity
0.75dl / g, acetaldehyde amount 5ppm, DEG content 2.1mol
%, Glass transition temperature 78 ° C, melting point 256 ° C, elevated crystallization temperature
The acid value was 168 ° C. and the acid value was 20 equivalents / ton. After attaching the label B to the bottle, the bottle was cut into about 1 cm squares with a shredder to form flakes. This is 95
It was immersed in a 3% aqueous sodium hydroxide solution at 30 ° C. with stirring for 30 minutes. The ink was completely removed from the label. After lifting the flakes and washing three times with water, 14
It was dried under a nitrogen atmosphere at 0 ° C. and 5 torr for 5 hours. The flakes were re-pelletized using a 30φ twin screw extruder (manufactured by Ikegai Iron & Steel Co., Ltd.). Cylinder temperature is 290
C. The average residence time was 150 seconds. The intrinsic viscosity of the regenerated pellets is 0.70 dl / g, the amount of acetaldehyde is 12 ppm, the crystallization temperature is 170 ° C., the acid value is 27 equivalents / ton, and the Co-b value is 1.5.
Met.

Example 2 A bottle was formed using polyethylene terephthalate inactivated by a germanium catalyst deactivated by water treatment with an intrinsic viscosity of 0.82.
Oligomer content of bottle body is 0.35% by weight, intrinsic viscosity 0.7
9. The amount of acetaldehyde was 3 ppm, the content of DEG was 2.0 mol%, the glass transition temperature was 78 ° C., the melting point was 253 ° C., and the crystallization temperature was 162 ° C. Thereafter, a regenerated pellet was obtained in the same manner as in Example 1 except that the label B was used. Of regenerated pellets. The intrinsic viscosity is
0.77 dl / g, the amount of oligomer was 0.38% by weight, the amount of acetaldehyde was 10 ppm, the crystallization temperature was 165 ° C., and the Co-b value was 1.4.

Comparative Example A bottle molded using a germanium-catalyzed polyethylene terephthalate having an intrinsic viscosity of 1.25 dl / g (the amount of oligomer in the bottle body is 0.7% by weight, the intrinsic viscosity is 1.17 dl / g, the amount of acetaldehyde is 27 ppm, and the content of DEG is 2.3 mol%. , Glass transition temperature 76
C., a melting point of 255.degree. C., and a temperature-raising crystallization temperature of 170.degree. C.). The oligomer content of the regenerated pellets was 0.72% by weight, the intrinsic viscosity was 0.83, the amount of acetaldehyde was 52 ppm, the crystallization temperature was 171 ° C., and the Co-b value was 2.6.

[0087]

According to the present invention, even if crushed and re-pelletized with the label attached, the obtained re-pellet has excellent crystallinity, little decrease in strength, furthermore, no off-odor and coloring, and is suitable for various uses. Can be used.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a process of recovering a thermoplastic polymer as a pellet from a labeled bottle of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 22:00 C08L 67:00 (72) Inventor Haruo Asai 2-2-2 Dojimahama, Kita-ku, Osaka-shi, Osaka No. Toyobo Co., Ltd. Headquarters F-term (reference) 3E033 AA01 BA17 CA20 EA20 4F070 AA47 DA05 FA03 FB06 4F073 AA21 AA23 BA23 BA24 BB03 EA03 EA11 EA41 4F301 AA25 AB03 BA01 BA02 BA12 BA21 BA29 BC13 BC26 BD08 BF18 BF33

Claims (4)

[Claims] 1. A hollow molded bottle made of a polyester resin having a label having an ink layer removable in alkaline hot water on at least one surface of a thermoplastic polymer film, wherein the intrinsic viscosity of the resin of the bottle is 0.60 to 0.60. 1.0dl
/ G in a hollow molded bottle. 2. A method for removing 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 above the label. 3. 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 2 is melted together with the bottle to which the label is attached, and regenerated. 4. A regenerated pellet obtained by the method according to claim 3.