WO2011096395A1 - Method for producing multilayered stretch-molded article - Google Patents

Abstract

Provided is a method for producing a multilayered stretch-molded article, comprising a crystallization step wherein a laminate body provided with a layer containing an amorphous polyglycolic acid based resin and an adjacent layer containing another thermoplastic resin is heated at a temperature of 50°C or more and less than 70°C to form a layer containing a crystallized polyglycolic acid based resin, so that the layer containing the crystallized polyglycolic acid based resin has a density of 1.540 g/cm3 or more; and a stretching step for stretch-molding the laminate body provided with the layer containing the crystallized polyglycolic acid based resin.

Description

Method for producing multilayer stretch molded product

The present invention relates to a method for producing a multilayer stretch molded product, and more particularly, to a method for producing a multilayer stretch molded product including a layer containing a polyglycolic acid resin and a layer containing another thermoplastic resin.

Polyglycolic acid is attracting attention as a biodegradable polymer material with a low environmental impact because it is excellent in microbial degradability and hydrolyzability. Polyglycolic acid is also excellent in gas barrier properties, heat resistance, and mechanical strength. However, although such a polyglycolic acid film is excellent in mechanical strength, it is not necessarily sufficient for use as a polyglycolic acid monolayer, and is not sufficient in moisture resistance and economy. There wasn't. For this reason, the polyglycolic acid layer is usually used in combination with other resin layers in multiple layers.

However, when a laminate comprising a polyglycolic acid layer and another resin layer is stretch-molded, the polyglycolic acid resin has high crystallinity and is easy to crystallize before stretch molding. When stretched, there was a problem that rupture or breakage occurred or a stretch group was likely to occur.

Therefore, in order to improve such a problem at the time of stretch molding, International Publication No. 2005/032800 (Patent Document 1) discloses that a laminate including a polyglycolic acid layer is thermoformed and cooled, and then made opaque. Until then, the polyglycolic acid layer is reheated and crystallized, and then a method for producing a multilayer stretch molded product is proposed in which the laminate is stretched.

In this method, the polyglycolic acid layer is reheated at a relatively high temperature of 80 to 200 ° C. until it becomes opaque, thereby forming a uniform crystal state. Thus, a multilayer stretched molded article having excellent gas barrier properties and transparency is obtained. Moreover, in the method of the said patent document 1, since it reheats at comparatively high temperature, there exists an advantage that a polyglycolic acid layer can be crystallized in a short heating time.

International Publication No. 2005/032800

However, when reheated at a relatively high temperature as in the method described in Patent Document 1, deformation occurs in stretch molding, and a multilayer stretched molded product having a predetermined shape and size cannot be stably obtained, and the yield is high. There was a case of decline. In addition, even when a predetermined multilayer stretch molded product is obtained, delamination (delamination) due to impact may occur between the polyglycolic acid layer and other resin layers, and resistance to delamination due to impact There was still room for improvement.

An object of the present invention is to provide a method capable of stably producing a multi-layer stretch-molded product that hardly causes delamination due to impact.

As a result of intensive studies to achieve the above object, the present inventors compared a laminate comprising a layer containing an amorphous polyglycolic acid resin and a layer containing another thermoplastic resin adjacent thereto. It is possible to crystallize a polyglycolic acid resin even when heated (aging) at a low temperature, and can reliably prevent deformation during stretch molding. It has been found that a multilayer stretched molded article having excellent delamination resistance due to impact can be obtained by heating the laminate so that the density of the resin-containing layer becomes a predetermined density, and the present invention has been completed. It was.

That is, the method for producing a multilayer stretched molded article of the present invention uses an amorphous polyglycolic acid resin so that the density of the layer containing the crystallized polyglycolic acid resin is 1.540 g / cm ³ or more. A crystallization step of forming a layer containing the crystallized polyglycolic acid resin by heating a laminate comprising a layer containing and a layer containing another thermoplastic resin adjacent thereto at 50 ° C. or higher and less than 70 ° C .; A stretching step of stretching (for example, stretch blow molding) a laminate including the crystallized polyglycolic acid resin-containing layer.

In the present invention, the thickness of the layer containing the amorphous polyglycolic acid resin is preferably 1 to 500 μm, and the thickness of the laminate is preferably 3.6 mm or less.

In the present invention, the other thermoplastic resins include polyester resins, polyolefin resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyurethane resins, ethylene / vinyl alcohol resins, ) At least one thermoplastic resin selected from the group consisting of acrylic acid resins, nylon resins, sulfide resins and polycarbonate resins is preferred.

In the present invention, the outermost layer of the laminate is selected from the group consisting of a polyester resin, a polystyrene resin, a polyvinyl chloride resin, a (meth) acrylic acid resin, a sulfide resin, and a polycarbonate resin. This is particularly useful when the layer contains at least one thermoplastic resin.

In the present invention, “amorphous” means a state in which 95% or more of the observation field is amorphous in the crystal state observation using a polarizing microscope. In addition, “crystallization” means a state in which 95% or more of the observation field is filled with spherulites in a crystal state observation using a polarizing microscope.

According to the present invention, it becomes possible to stably produce a multilayer stretched molded product that is less prone to delamination due to impact.

Hereinafter, the present invention will be described in detail on the basis of preferred embodiments thereof.

The method for producing a multilayer stretched molded product of the present invention includes:
Lamination comprising a layer containing an amorphous polyglycolic acid resin and a layer containing another thermoplastic resin adjacent thereto so that the density of the layer containing the crystallized polyglycolic acid resin becomes a predetermined density A crystallization step of heating the body at a predetermined temperature to form a layer containing the crystallized polyglycolic acid resin;
A stretching step of stretching and forming a laminate including the layer containing the crystallized polyglycolic acid resin;
It is a method including. By this method, it becomes possible to stably obtain a multilayer stretched molded article having excellent delamination resistance and transparency due to impact.

(Polyglycolic acid resin)
First, the polyglycolic acid resin (hereinafter referred to as “PGA resin”) according to the present invention will be described. As said PGA-type resin, following formula (1):
— [O—CH ₂ —C (═O)] — (1)
A glycolic acid homopolymer consisting only of glycolic acid repeating units represented by the formula (hereinafter referred to as “PGA homopolymer”, including a ring-opened polymer of glycolide which is a bimolecular cyclic ester of glycolic acid). And a polyglycolic acid copolymer containing glycolic acid repeating units (hereinafter referred to as “PGA copolymer”). Such PGA-type resin may be used individually by 1 type, or may use 2 or more types together.

The PGA homopolymer can be synthesized by dehydration polycondensation of glycolic acid, dealcohol polycondensation of glycolic acid alkyl ester, ring-opening polymerization of glycolide, or the like. Further, a PGA copolymer can be synthesized by using a comonomer in combination in these polycondensation reaction and ring-opening polymerization reaction.

Examples of the comonomer include ethylene oxalate (that is, 1,4-dioxane-2,3-dione), lactides, and lactones (for example, β-propiolactone, β-butyrolactone, β-pivalolactone, γ-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, ε-caprolactone, etc.), carbonates (eg, trimethylene carbonate), ethers (eg, 1,3-dioxane), ether esters (eg, Cyclic monomers such as dioxanone) and amides (such as ε-caprolactam); hydroxycarboxylic acids such as lactic acid, 3-hydroxypropanoic acid, 3-hydroxybutanoic acid, 4-hydroxybutanoic acid, 6-hydroxycaproic acid, or alkyls thereof Ester; ethylene glycol, 1, 4 It may be mentioned an aliphatic diol such as butanediol, succinic acid, a mixture of substantially equimolar with aliphatic dicarboxylic acids or their alkyl esters such as adipic acid. These comonomers may be used individually by 1 type, or may use 2 or more types together. Of such comonomers, cyclic monomers and hydroxycarboxylic acids are preferred from the viewpoint of heat resistance.

Examples of the catalyst used in the polycondensation reaction and ring-opening polymerization reaction include tin compounds such as tin halides and tin organic carboxylates; titanium compounds such as alkoxy titanates; aluminum compounds such as alkoxy aluminums; zirconium acetylacetone and the like And known catalysts such as antimony compounds such as antimony halides and antimony oxides.

The PGA-based resin can be produced by a known polymerization method such as melt polymerization, solid phase polymerization, or a combination thereof. The polymerization temperature is preferably 120 to 300 ° C., more preferably 130 to 250 ° C. 140 to 240 ° C is particularly preferable, and 150 to 230 ° C is most preferable. When the polymerization temperature is less than the lower limit, the polymerization tends not to proceed sufficiently. On the other hand, when the polymerization temperature exceeds the upper limit, the produced resin tends to be thermally decomposed.

The polymerization time of the PGA resin is preferably 2 minutes to 50 hours, more preferably 3 minutes to 30 hours, and particularly preferably 5 minutes to 20 hours. When the polymerization time is less than the lower limit, the polymerization does not proceed sufficiently, whereas when the upper limit is exceeded, the generated resin tends to be colored.

In the PGA resin according to the present invention, the content of the glycolic acid repeating unit represented by the formula (1) is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. 100 mass% is particularly preferable. If the content of the glycolic acid repeating unit is less than the lower limit, the crystallinity of the PGA resin is lowered, and the gas barrier property of the layer containing the PGA resin tends to be lowered.

The weight average molecular weight of the PGA resin is preferably 30,000 to 800,000, more preferably 50,000 to 500,000. If the weight average molecular weight of the PGA-based resin is less than the lower limit, the mechanical strength of the layer containing the PGA-based resin tends to decrease, whereas if it exceeds the upper limit, melt extrusion and injection molding tend to be difficult. The weight average molecular weight is a polymethylmethacrylate conversion value measured by gel permeation chromatography (GPC).

Further, the melt viscosity (temperature: 270 ° C., shear rate: 122 sec ⁻¹ ) of the PGA resin is preferably 50 to 3000 Pa · s, more preferably 100 to 2000 Pa · s, and particularly preferably 100 to 1000 Pa · s. . If the melt viscosity is less than the lower limit, the mechanical strength of the layer containing the PGA-based resin tends to decrease, whereas if it exceeds the upper limit, melt extrusion and injection molding tend to be difficult.

(Polyglycolic acid resin composition)
The PGA resin according to the present invention can be used as it is for the layer containing the amorphous PGA resin in the laminate used in the present invention. It is preferable to mix and use as a polyglycolic acid resin composition (hereinafter referred to as “PGA resin composition”). Mixing with a thermal stabilizer improves thermal stability, and mixing with a terminal blocker improves water resistance. Moreover, an inorganic filler, a plasticizer, another thermoplastic resin, etc. may be added to the PGA resin or the PGA resin composition as necessary, and further, a light stabilizer, a moistureproof agent, a waterproofing agent. Various additives such as an agent, a water repellent, a lubricant, a release agent, a coupling agent, a pigment, and a dye may be added.

Examples of the heat stabilizer include cyclic neopentanetetrayl bis (2,6-di-tert-butyl-4-methylphenyl) phosphite, cyclic neopentanetetrayl bis (2,4-di-tert-butyl). Phosphates having a pentaerythritol skeleton such as phenyl) phosphite and cyclic neopentanetetraylbis (octadecyl) phosphite; alkyl groups such as mono- or di-stearyl acid phosphate or mixtures thereof (preferably having a carbon number) 8-24) alkyl phosphates or phosphite alkyl esters; metal carbonates such as calcium carbonate and strontium carbonate; bis [2- (2-hydroxybenzoyl) hydrazine] dodecanoic acid, N, N′-bis [ 3- (3,5-Di- Hydrazine compounds having a —CONHNH—CO— unit such as —butyl-4-hydroxyphenyl) propionyl] hydrazine; Triazole compounds such as 3- (N-salicyloyl) amino-1,2,4-triazole; Triazine compounds Etc. These heat stabilizers may be used alone or in combination of two or more.

The amount of such a heat stabilizer added is preferably 0.001 to 3 parts by mass, more preferably 0.003 to 1 part by mass, and 0.01 to 0.05 parts by mass with respect to 100 parts by mass of the PGA resin. Part is particularly preferred. The mixing method of the PGA resin and the heat stabilizer is not particularly limited, and a known method such as dry blending or melt kneading can be applied. However, melt kneading is preferable because uniform mixing is possible. In addition, when melt kneading using an extruder, a thermal stabilizer is added to the PGA resin at the supply port of the extruder from the viewpoint of reducing mixing unevenness and improving the thermal stability of the PGA resin composition. Is preferred.

Examples of the end capping agent include carbodiimide compounds including monocarbodiimide and polycarbodiimide compounds such as N, N-2,6-diisopropylphenylcarbodiimide; 2,2′-m-phenylenebis (2-oxazoline), 2 , 2'-p-phenylenebis (2-oxazoline), 2-phenyl-2-oxazoline, styrene-isopropenyl-2-oxazoline and the like; 2-methoxy-5,6-dihydro-4H-1,3 -Oxazine compounds such as oxazine; epoxy compounds such as N-glycidyl phthalimide, cyclohexene oxide, and triglycidyl isocyanurate. These end capping agents may be used alone or in combination of two or more.

The amount of such an end-capping agent added is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 2 parts by mass, and 0.2 to 1 part by mass with respect to 100 parts by mass of the PGA resin. Is particularly preferred. The mixing method of the PGA-based resin and the end-capping agent is not particularly limited, and a known method such as dry blending or melt kneading can be applied, but melt kneading is preferable from the viewpoint of uniform mixing. In addition, when mixing (more preferably melt-kneading) the PGA-based resin, the thermal stabilizer, and the end-capping agent, the thermal stabilizer and the end-capping agent may be simultaneously added to the PGA-based resin. It is preferable to mix (more preferably melt knead) the PGA resin and the heat stabilizer, and then add and mix (more preferably melt knead) the end-capping agent to the melt kneaded product. For example, when melt-kneading a PGA-based resin, a heat stabilizer, and an end-capping agent using an extruder, first, the heat stabilizer is added to the PGA-based resin at the supply port of the extruder and melt-kneaded in a cylinder. In addition, it is preferable to add a terminal sealing agent to the middle of the cylinder using a side feeder or the like and melt knead. This tends to further improve the thermal stability and water resistance of the PGA resin composition.

Further, it is preferable to subject the obtained PGA resin composition to drying / demonomer treatment. Thereby, glycolide content in a PGA-type resin composition can be reduced, and it becomes possible to suppress the fall of water resistance. The drying temperature is preferably 120 to 225 ° C, more preferably 150 to 220 ° C. The drying time is preferably 0.5 to 95 hours, and more preferably 1 to 48 hours.

(Laminate)
The laminate used in the present invention comprises a layer containing an amorphous PGA resin (hereinafter referred to as “amorphous PGA resin layer”) and a layer containing another thermoplastic resin adjacent thereto (hereinafter referred to as “heat”). A plastic resin layer). As a method for producing such a laminate, for example, as described in JP-A No. 2003-20344, a PGA resin composition (or PGA resin) and other thermoplastic resins (or compositions thereof) ) In the form of a film and affixing them; PGA-based resin composition (or PGA-based resin) is formed into a film and this is formed from another thermoplastic resin (or its composition). A lamination method in which heat and pressure bonding with another film is performed through an adhesive formed by forming another thermoplastic resin (or a composition thereof) into a film shape, and a PGA resin composition (or PGA system) on the thermoplastic resin film Extrusion coating method for extruding resin); co-extrusion molding or co-extruding PGA resin composition (or PGA resin) and other thermoplastic resin (or composition thereof) Such as coextrusion or coinjection method which-molded and the like. The coextrusion method and the co-injection method have an advantage that the molding process is simple.

Examples of the thermoplastic resin include polyester resins such as polyethylene terephthalate and polylactic acid, polyolefin resins such as polyethylene, polypropylene, and ethylene / propylene copolymers, polystyrene resins such as polystyrene and styrene / butadiene copolymers, and polyvinyl chloride resins. Polyvinylidene chloride resin, polyurethane resin, ethylene / vinyl alcohol resin, (meth) acrylic acid resin, nylon resin, sulfide resin, polycarbonate resin and the like. These thermoplastic resins may be used alone or in combination of two or more. Among these, from the viewpoint of obtaining a multilayer stretched molded product that satisfies both desired transparency and gas barrier properties according to the use, a polyester-based resin is more preferable, and at least one of the diol component and the dicarboxylic acid component is an aromatic compound. Aromatic polyester resins are particularly preferred, and aromatic polyester resins obtained from aromatic dicarboxylic acids are most preferred.

In the present invention, the thickness of the laminate is preferably 3.6 mm or less, more preferably 3.4 mm or less, and particularly preferably 3.2 mm or less. If the thickness of the laminate exceeds the upper limit, an amorphous PGA-based resin layer is difficult to obtain, and delamination due to impact tends to occur in the multilayer stretched molded product.

In the method for producing a laminate, the amorphous PGA resin film or the amorphous PGA resin may be used as the molding temperature (set value) of the film containing the amorphous PGA resin or the amorphous PGA resin layer. There is no particular limitation as long as it is a temperature at which the layer is formed, but the lower limit is preferably a melting point Tm + 18 ° C. or higher, more preferably a melting point Tm + 23 ° C. or higher, and particularly preferably a melting point Tm + 28 ° C. or higher. If the molding temperature is set below the lower limit, it is difficult to obtain an amorphous PGA-based resin film or an amorphous PGA-based resin layer, and delamination due to impact tends to occur in the multilayer stretched molded product. Moreover, as an upper limit of shaping | molding temperature (setting value), 300 degrees C or less is preferable, 290 degrees C or less is more preferable, and 280 degrees C or less is especially preferable.

Further, the molding temperature of the thermoplastic resin film or the thermoplastic resin layer is appropriately set according to the physical properties of the thermoplastic resin to be used. For example, when polyethylene terephthalate (PET) is used as the thermoplastic resin, the molding temperature of the PET film or PET layer is preferably 280 to 310 ° C, more preferably 285 to 305 ° C. When the molding temperature of the PET film or the PET layer is less than the lower limit, an unmelted product is generated, and it tends to be difficult to obtain a target laminate. There is a tendency that molding becomes difficult due to conversion.

In the laminate used in the present invention, the thickness of the amorphous PGA resin layer is preferably 1 to 500 μm, more preferably 1 to 300 μm, and particularly preferably 1 to 200 μm. If the thickness of the amorphous PGA-based resin layer is less than the lower limit, the gas barrier property of the multilayer stretched molded product tends to decrease. On the other hand, if the thickness exceeds the upper limit, the PGA-based resin layer has a sufficient density in the crystallization step. However, delamination due to impact tends to occur in the multilayer stretched molded product.

In the laminate used in the present invention, the composition ratio of the amorphous PGA-based resin layer with respect to the entire laminate is preferably 1 to 10%, more preferably 1 to 5% on a mass basis. When the composition ratio of the amorphous PGA-based resin layer is less than the lower limit, the gas barrier property of the multilayer stretched molded product tends to be lowered. On the other hand, when the upper limit is exceeded, a large amount of stress is required at the time of stretch molding and multilayer stretching. The transparency of the molded product tends to decrease.

<Method for producing multilayer stretch molded product>
The method for producing a multilayer stretched molded product of the present invention comprises heating a laminate comprising the above amorphous PGA resin layer and a thermoplastic resin layer adjacent thereto to crystallize the amorphous PGA resin layer. It is a method including a step of crystallizing (crystallization step) and a step of stretching and molding the laminate obtained thereby (stretching step).

(Crystallization process)
In the crystallization process according to the present invention, the laminate including the amorphous PGA resin layer is heated so that the density of the crystallized PGA resin layer is 1.540 g / cm ³ or more. As a result, it is possible to obtain a multilayer stretched molded article having excellent delamination resistance and transparency due to impact. In particular, when the density of the crystallized PGA resin layer is less than the lower limit, crystallization is insufficient, and delamination due to impact occurs in the multilayer stretched molded product. Note that the crystallization of the amorphous PGA resin layer can be confirmed by observing the crystallization state using a polarizing microscope. That is, if the density of the crystallized PGA-based resin layer is 1.540 g / cm ³ or more, 95% or more of spherulites are present.

In addition, from the viewpoint that a multilayer stretched molded product having excellent delamination resistance and transparency due to impact can be obtained more reliably, the density of the crystallized PGA resin layer is preferably 1.545 g / cm ³ or more. 1.550 g / cm ³ or more is more preferable. The upper limit of the density of the crystallized PGA resin layer is preferably 1.580 g / cm ³ or less.

In the present invention, in order to form a crystallized PGA resin layer having such a density, the laminate including the amorphous PGA resin layer is heated at 50 ° C. or higher and lower than 70 ° C. At such a heating temperature, in order to increase the density of the crystallized PGA resin layer, even when heated for a long time, deformation during stretch molding hardly occurs, and multi-layer stretching excellent in delamination resistance and transparency due to impact. It becomes possible to produce a molded product with high yield.

On the other hand, when the heating temperature is less than the lower limit, it becomes difficult to crystallize the amorphous PGA resin layer so that the crystallized PGA resin layer has the density, and the resulting multilayer stretched molded product is crystallized. Delamination due to impact occurs between the PGA resin layer and the thermoplastic resin layer. On the other hand, in order to increase the density of the crystallized PGA-based resin layer, crystallization and densification of the crystallized PGA-based resin layer proceed sufficiently when heated at a temperature exceeding the upper limit for a long time. It becomes difficult to obtain a multilayer stretch molded product stably because the laminate including the resin layer is easily deformed.

In the present invention, from the above viewpoint, the crystallized PGA-based resin layer having the above density is more reliably formed, and the deformation during the stretch molding of the laminate is surely prevented to prevent delamination due to impact and In order to stably produce a multilayer stretched molded article having excellent transparency, the heating temperature is preferably set to 55 ° C. or higher and 65 ° C. or lower.

Thus, since the heating temperature is relatively low in the crystallization step according to the present invention, a thermoplastic resin having a low glass transition temperature (for example, polyester resin, polystyrene resin, polyvinyl chloride resin, (meth) acrylic). The present invention is particularly useful when producing a multilayer stretched molded article having an outermost layer containing an acid resin, sulfide resin, or polycarbonate resin.

The heating time in the crystallization process according to the present invention is such that the shape of the laminate, the thickness of the amorphous PGA resin layer, and the heating temperature are used so that the crystallized PGA resin layer having the above density can be obtained with certainty. Set according to. For example, when a laminated body having an amorphous PGA resin layer with a thickness of 1 to 300 μm (preferably 1 to 200 μm) is heated at 50 ° C. or higher and lower than 70 ° C., the heating time is set to 1 to 10 hours. In addition, when a laminated body having an amorphous PGA resin layer thickness of 300 to 500 μm is heated at 50 ° C. or more and less than 70 ° C., the heating time is set to 2 to 48 hours (preferably 3 to 30 hours). . If the heating time is less than the lower limit, the amorphous PGA resin layer may not be sufficiently crystallized, and a crystallized PGA resin layer having the density may not be obtained. On the other hand, if the upper limit is exceeded, crystallization may proceed excessively, and stretch molding may be difficult.

In the crystallization process according to the present invention, since the laminate is heated at the heating temperature and heating time described above, it is possible to use a known heating device such as a hot air dryer, an infrared heater, an electromagnetic heater, or a heating medium heater. it can.

(Stretching process)
The stretching step according to the present invention is a step of stretch-molding the laminate obtained in the crystallization step, that is, a laminate comprising the crystallized PGA resin layer. Thereby, generation | occurrence | production of the delamination by the impact between a crystallized PGA type-resin layer and a thermoplastic resin layer is suppressed, and the multilayer stretched molding excellent in gas barrier property and transparency can be obtained. In particular, in the present invention, as described above, the density of the PGA resin layer is increased by performing heat treatment at a relatively low temperature on the laminate including the amorphous PGA resin layer in advance. In this stretching step, the laminate is hardly deformed, and a multilayer stretched molded product having a predetermined shape and dimensions can be obtained stably.

The stretch molding method is not particularly limited, and known stretching methods described in JP-A No. 2003-20344, JP-A No. 2003-136657, JP-T No. 2005-526642, International Publication No. 2006/107099, and the like. A molding method, a stretch blow molding method, or the like can be employed.

The shape of the multilayer stretched molded product thus obtained is not particularly limited, and examples thereof include a film shape, a sheet shape, and a hollow shape. Specifically, a multilayer stretched film, a multilayer stretched sheet, and a multilayer stretched hollow Examples include containers.

Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples. The physical properties of the PGA resin, PGA resin composition, preform and bottle were evaluated by the following methods.

<Polymerization reaction rate>
A certain amount of PGA resin was added to dimethyl sulfoxide (manufactured by Kanto Chemical Co., Ltd.) in which 4-chlorobenzophenone (manufactured by Kanto Chemical Co., Ltd.) was dissolved at a constant concentration as an internal standard substance. The precipitate was filtered. The filtrate was analyzed using gas chromatography (“GC-2010” manufactured by Shimadzu Corporation) under the following conditions, the glycolide content in the PGA resin was determined, and the polymerization reaction rate was calculated.

(Analysis conditions)
Column: TC-17 (0.25mmφ × 30m)
Column temperature: After holding at 150 ° C., the temperature was raised to 270 ° C. and held for a certain time.
Injection temperature: 180 ° C
Detector: FID (hydrogen flame ionization detector, temperature 300 ° C.).

<Melting point>
Using a differential scanning calorimeter (“DSC30 / TC15” manufactured by METTLER TOLEDO), the mixture was heated to 280 ° C. while increasing the temperature from −50 ° C. to 20 ° C./min under a nitrogen flow. The maximum point temperature of the endothermic peak due to melting during heating was defined as the melting point of the PGA resin.

<Molecular weight>
A sufficiently dried PGA resin was melt-pressed with a heat press at 275 ° C. and immediately cooled immediately to prepare a transparent amorphous sheet. A sample was cut out from the amorphous sheet and dissolved in hexafluoroisopropanol (HFIP, manufactured by DuPont) in which sodium trifluoroacetate (manufactured by Kanto Chemical Co., Ltd.) was dissolved at a concentration of 5 mM to prepare a sample solution. This sample solution was filtered through a membrane filter (PTFE, pore size: 0.1 μm) and then injected into gel permeation chromatography (“Shodex GPC-104” manufactured by Showa Denko KK). The number average molecular weight and the weight average molecular weight were measured, and the polydispersity (= weight average molecular weight / number average molecular weight) was calculated. The sample solution was injected into the GPC apparatus within 30 minutes after the amorphous sheet was dissolved.

(Analysis conditions)
Column: HFIP-606M (2 pieces), pre-column: HFIP-G (1 piece) connected in series Column temperature: 40 ° C
Eluent: HFIP solution of 5 mM sodium trifluoroacetate Flow rate: 0.6 ml / min Detector: RI (differential refractive index detector)
Molecular weight determination reference material: standard polymethyl methacrylate (manufactured by Showa Denko KK).

<Density>
The inner and outer layers of the preform were peeled off, and an intermediate layer (PGA resin layer) was collected. Six-stage density gradient tubes were prepared using dichloromethane and carbon tetrachloride in a density range of 1.48 to 1.58 g / cm ³ , and the density of the PGA resin layer was measured using these.

<Crystallization temperature Tc1 and calorific value ΔHc1>
The inner and outer layers of the preform are peeled to collect an intermediate layer (PGA resin layer), and a differential scanning calorimeter (“DSC30 / TC15” manufactured by METTLER TOLEDO) is used, and the temperature is 0 ° C. to 20 ° C. under nitrogen flow. The temperature was raised at / min. The maximum temperature of the exothermic peak corresponding to crystallization at the time of temperature rise was defined as the crystallization temperature Tc1 of the PGA resin layer. Further, the heat generation amount ΔHc1 at the time of crystallization was determined from this heat generation peak.

<Crystallization temperature Tc2>
The sufficiently dried PGA resin composition was melt-pressed with a heat press at 280 ° C. to prepare a 200 μm sheet. A predetermined amount is cut out from this sheet and heated to 280 ° C. while increasing the temperature from −50 ° C. to 20 ° C./min under a nitrogen flow using a differential scanning calorimeter (“DSC30 / TC15” manufactured by METTLER TOLEDO). did. Then, it cooled to room temperature at 20 degree-C / min. The maximum temperature of the exothermic peak due to crystallization during cooling was defined as the crystallization temperature Tc2 of the PGA resin composition.

<Bottle yield>
The ratio of bottles obtained in a predetermined shape and size was determined with respect to the total number of three-layer preforms subjected to stretch blow molding.

<Surface roughness Ra>
The inner and outer layers of the bottle were peeled off, and an intermediate layer (PGA resin layer) was collected. According to the method described in JIS B0601, the surface roughness of the PGA resin layer (the roughness of the interface with the outer PET layer) was measured using a stylus type surface roughness meter ("Surfcom 550AD" manufactured by Tokyo Seimitsu Co., Ltd.). It was measured. The measurement conditions were a stylus cone type 5 μmR, a measurement force of 4 mN or less, and a cutoff of 0.08 mm. In addition, about the same sample, the place was arbitrarily changed and the said measurement was implemented 10 times, and the arithmetic mean value of the obtained result was made into arithmetic mean surface roughness Ra.

<Delamination resistance>
The bottle was filled with 4.2 atmospheres of carbonated water, the stopper was closed, and the bottle was allowed to stand at 23 ° C. for 24 hours. Then, a pendulum impact test was performed, and delamination between the outer PET layer and the intermediate layer (PGA resin layer) was observed. The presence or absence was observed. This impact test was performed on 20 bottles, and the number of bottles in which delamination did not occur was measured.

The PGA resin and PGA resin composition used in Examples and Comparative Examples were prepared by the following method.

<Preparation of PGA resin>
In accordance with the method described in International Publication No. 2007/086563, a catalyst was prepared such that high-purity glycolide (manufactured by Kureha Co., Ltd.) as a raw material monomer and 1-dodecanol as an initiator was 0.2 mol% based on glycolide. As a starting material, tin dichloride was charged into a reactor so as to be 30 ppm with respect to glycolide, and continuously polymerized with an average residence time of 20 minutes while being controlled at 200 to 210 ° C. The obtained polymer was taken out in the form of particles, and this was further subjected to solid phase polymerization at 170 ° C. for 3 hours while stirring in a nitrogen atmosphere. As a result, the final polymerization reaction rate is 99% or more, the melting point (peak temperature in melting) is 222 ° C., the weight average molecular weight is 200,000, and the polydispersity (= weight average molecular weight / number average molecular weight) is 2.0. The powdery PGA resin was obtained.

<Preparation of PGA resin composition>
A PGA resin composition was prepared using a twin-screw kneading extruder (“TEM41SS” manufactured by Toshiba Machine Co., Ltd.). This twin-screw kneader-extruder is equipped with an electric heater that can individually control the temperature in 13 regions. This temperature was controlled so that the maximum temperature of the cylinder of the extruder was 275 ° C.

The powdery PGA resin was continuously supplied to the biaxial kneading extruder. At this time, the thermal stabilizer (“ADK STAB AX-71” manufactured by Asahi Denka Kogyo Co., Ltd.) was added at a ratio of 0.020 parts by mass with respect to 100 parts by mass of PGA resin, and N, N-2, 6-Diisopropylphenylcarbodiimide (“DIPC” manufactured by Kawaguchi Chemical Industry Co., Ltd.) was continuously supplied in a molten state at a ratio of 0.3 part by mass with respect to 100 parts by mass of the PGA resin, and melt-kneaded. The strand discharged from the die of the extruder was cooled and cut using a pelletizer to obtain a pellet-like PGA resin composition. The obtained pellet was heat-treated at 170 ° C. for 17 hours. The glycolide content of the PGA resin composition was 0.1% by mass or less, and the crystallization temperature Tc2 was 134 ° C.

Example 1
<Co-injection molding>
The PGA resin composition prepared as described above was used as the intermediate layer resin, and the inner and outer layer resins were polyethylene terephthalate (“CB602S” manufactured by Totobo Co., Ltd., weight average molecular weight: 20,000, melt viscosity (temperature: 290 ° C., Using a co-injection molding machine having a shear rate of 122 sec ⁻¹ ): 550 Pa · s, a glass transition temperature: 75 ° C., and a melting point: 249 ° C. A colorless and transparent bottle preform (preform thickness: 3.15 mm, PGA resin layer thickness: 200 μm) composed of three layers of PGA / PET (PGA filling amount: 3 mass%). Reform ”). At this time, the temperature of the intermediate layer barrel and the runner was set to 255 ° C, and the temperature of the inner and outer layer barrels and the runner was set to 290 ° C. When the crystallization state of the intermediate layer (PGA resin layer) of the obtained three-layer preform was observed using a polarizing microscope (“BH-2” manufactured by Olympus Corporation), no crystals were formed in the entire observation field. It was confirmed that they did not.

<Aging>
The three-layer preform produced as described above was heated in a hot air dryer set at 60 ° C. for 4 hours. The density of the intermediate layer (PGA resin layer) of the three-layer preform after the heat treatment was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

<Stretch blow molding>
The three-layer preform subjected to the heat treatment (aging treatment) as described above is preheated to 110 ° C. using a stretch blow molding machine (manufactured by Frontier Co., Ltd.), blow-molded at this temperature, and subjected to PET / PGA. A colorless and transparent bottle composed of 3 layers of PET / PET (PGA filling amount: 3% by mass) was obtained. With respect to this bottle, the yield, arithmetic average surface roughness (roughness of the interface with the outer PET layer) Ra, and delamination resistance were measured according to the above methods. The results are shown in Table 1.

Further, the three-layer preform subjected to the aging treatment as described above was separately preheated to 110 ° C. using the stretch blow molding machine and then rapidly cooled. The density of the intermediate layer (PGA resin layer) of the three-layer preform was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

(Example 2)
<Aging>
A three-layer preform produced in the same manner as in Example 1 was heated in a hot air dryer set at 65 ° C. for 1 hour. The density of the intermediate layer (PGA resin layer) of the three-layer preform after the heat treatment, the crystallization temperature Tc1, and the calorific value ΔHc1 during crystallization were measured according to the above methods. The results are shown in Table 1.

<Stretch blow molding>
The three-layer preform subjected to the aging treatment as described above is stretch blow molded in the same manner as in Example 1 and is a colorless and transparent bottle comprising three layers of PET / PGA / PET (PGA filling amount: 3 mass%). Got. With respect to this bottle, the yield, arithmetic average surface roughness (roughness of the interface with the outer PET layer) Ra, and delamination resistance were measured according to the above methods. The results are shown in Table 1.

Further, the three-layer preform subjected to the aging treatment as described above was separately preheated to 110 ° C. using the stretch blow molding machine and then rapidly cooled. The density of the intermediate layer (PGA resin layer) of the three-layer preform was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

(Comparative Example 1)
For the three-layer preform produced in the same manner as in Example 1, the density, the crystallization temperature Tc1, and the calorific value ΔHc1 during crystallization were measured according to the above methods. The results are shown in Table 1.

<Stretch blow molding>
A bottle consisting of three layers of PET / PGA / PET (PGA filling amount: 3 mass%) was obtained in the same manner as in Example 1 except that the three-layer preform was stretch blow molded without performing the aging treatment. With respect to this bottle, the yield, arithmetic average surface roughness (roughness of the interface with the outer PET layer) Ra, and delamination resistance were measured according to the above methods. The results are shown in Table 1.

Further, the three-layer preform not subjected to the aging treatment was separately preheated to 110 ° C. using the stretch blow molding machine and then rapidly cooled. For the intermediate layer (PGA resin layer) of this three-layer preform, the density, the crystallization temperature Tc1, and the calorific value ΔHc1 at the time of crystallization were measured according to the above methods. The results are shown in Table 1.

(Comparative Example 2)
<Aging>
A three-layer preform produced in the same manner as in Example 1 was heated in a hot air dryer set at 70 ° C. for 0.5 hour. The density of the intermediate layer (PGA resin layer) of the three-layer preform after the heat treatment was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

<Stretch blow molding>
The three-layer preform subjected to the aging treatment as described above is stretch blow molded in the same manner as in Example 1 and is a colorless and transparent bottle comprising three layers of PET / PGA / PET (PGA filling amount: 3 mass%). Got. With respect to this bottle, the yield and arithmetic average surface roughness (roughness of the interface with the outer PET layer) Ra were measured according to the methods described above. The results are shown in Table 1.

Further, the three-layer preform subjected to the aging treatment as described above was separately preheated to 110 ° C. using the stretch blow molding machine and then rapidly cooled. The density of the intermediate layer (PGA resin layer) of the three-layer preform was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

(Comparative Example 3)
<Aging>
A three-layer preform produced in the same manner as in Example 1 was heated in a hot air dryer set at 75 ° C. for 0.5 hour. The density of the intermediate layer (PGA resin layer) of the three-layer preform after the heat treatment was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

<Stretch blow molding>
The three-layer preform subjected to the aging treatment as described above is stretch blow molded in the same manner as in Example 1 and is a colorless and transparent bottle comprising three layers of PET / PGA / PET (PGA filling amount: 3 mass%). Got. With respect to this bottle, the yield and arithmetic average surface roughness (roughness of the interface with the outer PET layer) Ra were measured according to the methods described above. The results are shown in Table 1.

Further, the three-layer preform subjected to the aging treatment as described above was separately preheated to 110 ° C. using the stretch blow molding machine and then rapidly cooled. The density of the intermediate layer (PGA resin layer) of the three-layer preform was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

(Comparative Example 4)
<Co-injection molding>
Example 1 except that the temperature of the intermediate layer barrel and runner was changed to 245 ° C., and the injection amount of the resin was adjusted so that the preform thickness was 4.10 nm and the PGA resin layer thickness was 260 μm. In the same manner, a colorless and transparent bottle preform (hereinafter referred to as “three-layer preform”) composed of three layers of PET / PGA / PET (PGA filling amount: 3 mass%) was produced.

When the crystallization state of the intermediate layer (PGA resin layer) of the obtained three-layer preform was observed using a polarizing microscope (“BH-2” manufactured by Olympus Corporation), crystals were generated over the entire observation field. It was confirmed that Further, the density of the intermediate layer (PGA resin layer) of this three-layer preform was measured according to the above method. The results are shown in Table 1. Furthermore, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

<Stretch blow molding>
A colorless and transparent bottle composed of three layers of PET / PGA / PET (PGA filling amount: 3 mass%) was obtained in the same manner as in Example 1 except that the three-layer preform was stretch blow molded without being subjected to aging treatment. It was. With respect to this bottle, the yield, arithmetic average surface roughness (roughness of the interface with the outer PET layer) Ra, and delamination resistance were measured according to the above methods. The results are shown in Table 1.

Further, the three-layer preform not subjected to the aging treatment was separately preheated to 110 ° C. using the stretch blow molding machine and then rapidly cooled. The density of the intermediate layer (PGA resin layer) of the three-layer preform was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

(Comparative Example 5)
<Co-injection molding>
A colorless and transparent bottle preform comprising three layers of PET / PGA / PET (PGA filling amount: 3 mass%) in the same manner as in Example 1 except that the temperature of the intermediate layer barrel and runner was changed to 235 ° C. Preform thickness: 3.15 mm, PGA resin layer thickness: 200 μm (hereinafter referred to as “three-layer preform”).

When the crystallization state of the intermediate layer (PGA resin layer) of the obtained three-layer preform was observed using a polarizing microscope (“BH-2” manufactured by Olympus Corporation), crystals were generated over the entire observation field. It was confirmed that Further, the density of the intermediate layer (PGA resin layer) of this three-layer preform was measured according to the above method. The results are shown in Table 1. Furthermore, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

<Stretch blow molding>
A colorless and transparent bottle composed of three layers of PET / PGA / PET (PGA filling amount: 3 mass%) was obtained in the same manner as in Example 1 except that the three-layer preform was stretch blow molded without being subjected to aging treatment. It was. With respect to this bottle, the yield, arithmetic average surface roughness (roughness of the interface with the outer PET layer) Ra, and delamination resistance were measured according to the above methods. The results are shown in Table 1.

Further, the three-layer preform not subjected to the aging treatment was separately preheated to 110 ° C. using the stretch blow molding machine and then rapidly cooled. The density of the intermediate layer (PGA resin layer) of the three-layer preform was measured according to the above method. The results are shown in Table 1. Further, when the crystallization temperature Tc1 of the PGA resin layer and the calorific value ΔHc1 during crystallization were measured according to the above methods, no exothermic peak was detected.

As is apparent from the results shown in Table 1, according to the production method of the present invention (Examples 1 and 2), the amorphous PGA resin layer was subjected to aging treatment at a predetermined temperature to obtain crystals having a predetermined density. By forming a crystallized PGA resin layer, it is equipped with a crystallized PGA resin layer with a smooth interface with the outer PET layer without deformation of the three-layer preform during stretch blow molding, and is resistant to delamination and transparency due to impact It was confirmed that a multilayer stretched molded product (bottle) having excellent properties can be obtained in a high yield.

Moreover, in Example 1, since the exothermic peak by crystallization was not detected in the PGA resin layer after the aging treatment, it was confirmed that the PGA resin layer was completely crystallized by the aging treatment. On the other hand, in Example 2, crystallization of the PGA resin layer occurred, but an exothermic peak due to crystallization was detected in the PGA resin layer after the aging treatment, and the amorphous PGA resin remained. However, if the density of the PGA resin layer after the aging treatment is 1.545 g / cm ³ or more, the remaining amorphous PGA resin can be crystallized by preheating at the time of stretch blow molding, and at the time of stretch blow molding ( After preheating), it was confirmed that the PGA resin layer was completely crystallized.

On the other hand, when a three-layer preform having an amorphous PGA resin layer is stretch blow molded without performing an aging treatment (Comparative Example 1), the smoothness of the surface of the PGA resin layer in contact with the outer PET layer is low. Low, delamination due to impact occurred between the PGA resin layer and the outer PET layer. The reason is presumed as follows. That is, when the aging treatment is not performed, as shown in Table 1, the PGA resin layer has a low density and is amorphous. When a three-layer preform including an amorphous PGA resin layer is stretch blow molded, only a part of the amorphous PGA resin layer is crystallized by preheating, and a PGA resin layer having a non-uniform crystal state is formed. When a three-layer preform including such a PGA resin layer is stretched, the interface with the outer PET layer becomes rough, and it is assumed that delamination due to impact occurred.

In addition, when the amorphous PGA resin layer is subjected to an aging treatment at 70 ° C. or higher (Comparative Examples 2 to 3), the three-layer process is performed so that the density of the PGA resin layer is 1.540 g / cm ³ or higher. It was found that even if the aging treatment was applied to the reform, a bottle having a desired shape and size could not be stably obtained in the subsequent stretch blow molding, and the yield of the target bottle was lowered.

Further, when a three-layer preform having a crystallized PGA resin layer without aging treatment is stretch blow molded (Comparative Examples 4 to 5), the density of the crystallized PGA resin layer is 1.540 g / cm 3. Even if it is ³ or more, since the amorphous material is not crystallized, the smoothness of the surface in contact with the outer PET layer of the PGA resin layer is low, and impact is caused between the PGA resin layer and the outer PET layer. Due to delamination. The reason is presumed as follows. That is, the PGA resin layer crystallized in the preform molding process has a non-uniform crystal state, and when a three-layer preform provided with such a PGA resin layer is stretched, the interface with the outer PET layer becomes rough. Therefore, it is presumed that delamination due to impact occurred.

As described above, according to the present invention, it is possible to reliably prevent deformation at the time of stretch molding and stably produce a multilayer stretch molded product excellent in delamination resistance and transparency due to impact. Become.

Therefore, the method for producing a multilayer stretched molded product of the present invention is a method capable of producing a multilayer stretched molded product with a high yield, and is useful as a method suitable for mass production of the multilayer stretched molded product.

Claims (6)

A layer containing an amorphous polyglycolic acid resin and a layer containing another thermoplastic resin adjacent thereto so that the density of the crystallized polyglycolic acid resin containing layer is 1.540 g / cm ³ or more. A crystallization process of forming a layer containing the crystallized polyglycolic acid resin by heating a laminate comprising:
A stretching step of stretching and forming a laminate including the layer containing the crystallized polyglycolic acid resin;
A method for producing a multilayer stretched molded product comprising: The method for producing a multilayer stretch molded product according to claim 1, wherein the layer containing the amorphous polyglycolic acid resin has a thickness of 1 to 500 µm. The method for producing a multilayer stretch molded product according to claim 1 or 2, wherein the thickness of the laminate is 3.6 mm or less. The other thermoplastic resins are polyester resin, polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyurethane resin, ethylene / vinyl alcohol resin, (meth) acrylic acid resin. The production of a multilayer stretch molded product according to any one of claims 1 to 3, which is at least one thermoplastic resin selected from the group consisting of nylon resin, sulfide resin and polycarbonate resin. Method. The outermost layer of the laminate is at least one thermoplastic selected from the group consisting of polyester resins, polystyrene resins, polyvinyl chloride resins, (meth) acrylic acid resins, sulfide resins and polycarbonate resins. The method for producing a multilayer stretch-molded product according to any one of claims 1 to 4, which is a layer containing a resin. The method for producing a multilayer stretch molded product according to any one of claims 1 to 5, wherein the stretch molding is stretch blow molding.