JPH01182023A - Co-injection orientation blow molded container - Google Patents

Abstract

PURPOSE:To improve release properties between shock-resistant layers by providing a composition consisting of thermoplastic polyester inner and outer surface layers, and an intermediate layer having specific components. CONSTITUTION:The subject container comprises inner and outer surface layers of thermoplastic polyester (D) and an intermediate layer, which is composed of a saponified matter (A) of ethylene-vinyl acetate copolymer wherein ethylene content is 20-60mol%, saponification degree of vinyl acetate is at least 95% and a metalcontaining polyester thermoplastic resin (B) which satisfies formula I, blended in 5-40 pts.wt. based on 100 pts.wt. of the saponified matter (A), and is heat-treated at temperature shown by formula II. The thermoplastic polyester (D) is a compound containing 1-20 pts.wt. of resin (B) based on 100 pts.wt. of thermoplastic polyester; the resin (B) is a thermoplastic polyester containing 0.5-5mol of one or more elements selected from the group of Al, Cr, Sn, Ge and Si based on 100mol of dicarboxylic acid component.

Description

[Detailed description of the invention] A. *Field of industrial application The present invention provides gas barrier properties such as oxygen or carbon dioxide,
Synthetic resin co-injection stretch-blown containers used for containers for beverages, foods, cosmetics, etc. that have moisture resistance, aroma retention, flavor barrier properties, and good appearance, especially thermoplastic polyester C
(hereinafter abbreviated as PES) as the inner and outer surface layers, and ethylene-
The intermediate layer is a saponified vinyl acetate copolymer (hereinafter abbreviated as EV OH) composition, and has at least a three-layer structure, in particular, the impact resistance to delamination (hereinafter abbreviated as delamination) has been improved to that of dog rIJ. , relating to co-injection stretch-blown containers.

B. Conventional technology Polyester containers made by stretch blow molding are used in many fields due to their excellent transparency and rigidity.
Because gas barrier properties are not always sufficient, food products can only be stored for a limited period of time.

In order to improve this drawback, various methods have been proposed to create a multilayer structure by combining polyester with ethylene-vinyl alcohol co-T (co-T), which has good gas barrier properties. In other words, a method of manufacturing a preform before stretch-blowing. There are co-extrusion molding methods, multi-stage injection molding methods, co-injection molding methods, etc., each of which has advantages and disadvantages.Among these, the co-injection molding method requires simple equipment and is completely covered with EVOH or PES. This method is currently attracting attention because it has the advantage of creating a multilayer container with a good appearance due to the adhesion effect of atmospheric pressure even without adhesive resin between EVOH and PES. However, in actual use,
When a container is filled with food and subjected to impact, PES and EVO
Delamination occurred between the H and H, which was a big problem in terms of appearance.

Therefore, a base material including an adhesive layer (hereinafter abbreviated as Ad)/
Ad/E VOH/Ad/Base material (Unexamined Japanese Patent Publication No. 1983)
-501040) composition or base material/Aa/EvoH
/Ad/Base material/Ad/EV OH/ Ad/Base material (
JP-A No. 50-135169, No. 61-152411,
Co-injection molding methods with configurations such as 61-152412 and 61-259944 have been considered, but the equipment is extremely complex, and it is often difficult to control the thickness of each layer, resulting in lower manufacturing costs and production costs. In terms of performance, it is inferior to other methods such as coextrusion molding (pipe method). An even more serious problem is that impact delamination is often not completely improved even in multilayer co-injection stretch-blown containers containing the above adhesive resin layer. In other words, even if the adhesive strength (T total peel strength) between PES and EVOH on the container body is relatively high at 400 to 600 f/10 m width, impact delamination may be very strong. On the other hand, on the other hand, the above adhesive strength is 20 to 40 f/
Even if the container has a width of 106 and is barely bonded, impact delamination may be less likely to occur than containers with the above-mentioned high adhesive strength. In this way, impact delamination is a difficult problem because the cause is not so new, and improvements are desired.

C1 Problems to be Solved by the Invention EVOH was laminated as a gas barrier resin without containing an independent adhesive resin layer. PES-based co-injection stretch-blow molded containers have the problem that when they are empty, filled with normal pressure, or filled with high-pressure contents and subjected to impact, delamination occurs between the PES layer and the EVOH layer, resulting in poor appearance of the container. Ta. Therefore, the present inventors conducted extensive studies on methods for preventing delamination.

00 Means for Solving the Problems The present inventors applied E to the inner and outer surface layers of PES using a co-injection molding method.
When manufacturing a multilayer preform with an intermediate layer in which VOH or PES and EVOH are completely encapsulated by the inner and outer surface layers, and then stretch blow molding the multilayer parison to manufacture a container, the EVOH layer and the EVOH layer due to the impact of the container are manufactured. In order to prevent interlayer delamination with the PES layer, we conducted extensive research on the composition of EVOH. As a result, surprisingly, E
An E V OH composition (A) in which a metal-containing polyester resin (B) satisfying the following formula (1) is bundled
C) Used and co-injection molded, EVOH of the bottle body
The adhesive strength (T total peel strength) between the composition layer and the PES layer is 3
Although it is extremely weak with a width of about 0 to 100V/101111, it was found that delamination due to giJ impact of a container filled with normal pressure or pressurized water is difficult to occur, and this led to the completion of the present invention.

By the way, the E V′ 0 )L composition (C) and the P E
Using S (D), a pipe is made with a two-type three-layer co-extrusion device, and after forming a bottomed parinone, a container or EVO) I (A), resin (B), and the PE are heated and stretched and blow-molded.
Containers stretched and blown from pipes using S (D) using a three-layer, five-layer coextrusion device may exhibit relatively high adhesive strength at the container body, but delamination due to impact may occur. It has been found that this is likely to occur. In other words, although the cause is not obvious, the above EVOH composition (
It is unexpected that only when C) is used, a large impact resistance is achieved. This fact is also clear from the following examples. 1. In the present invention, it is not particularly necessary to provide an independent adhesive resin layer between (D) and (C), but a core layer may be provided, for example, a thin core layer may be provided.

1≦MI (B) / IVII (A)≦100 −
----- (T) However, MI (A), (B) is the melt index (2160f, 2
By the way, co-injection stretch-blown containers molded with the above composition not only have significantly improved impact delamination properties, but surprisingly, delamination tends to occur in the container body, especially at the bottom and around the mouth. It was found that the thickness unevenness of the EVOH layer in the form of vertical stripes was greatly improved. - PES and E'VOH for boat fishing
In co-injection and co-stretching operations with PES, EVOH has poor stretchability compared to PES, so it tends to cause uneven elongation, especially unevenness and streaks in the longitudinal direction of the bottle, and tends to cause poor appearance. Therefore, when using the above EVOH composition (C), the cause of the significant improvement in vertical streaks is not the shad, but
By blending the resin (B) with EVOH (A), the EVOH composition (C) is mixed with EVOH (A).
The elongation was improved, and the EVOH composition (C)
It is presumed that this is because the interaction with S prevented the occurrence of strong masis.

In addition, in order to further improve the impact resistance, as a result of intensive studies, we used a saponified ethylene-vinyl acetate copolymer containing 02 to 0.0002 mole of vinylsilane compound units as the EVOH resin (A). If there was
Surprisingly, we were able to complete the present invention by further improving the impact resistance and delamination properties. This fact is also clear from the examples described below.

As PE5(D) used in the present invention, a condensation polymer mainly composed of aromatic dicarboxylic acids or their alkyl esters and glycol is used. PES mainly composed of is preferable. Dicarboxylic acid components such as isophthalic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, or alkyl ester derivatives thereof, propylene glycol, 1.4- Butanediol, cyclohexane dimetatool, neopentyl glycol,
It is also possible to use a copolymer obtained by copolymerizing a glycol component such as bisphenol A1 diethylene glycol. The intrinsic viscosity [η] (unit: dllf) measured at a temperature of 30°C after dissolving in a mixed solvent of 50% by weight of phenol and 50% by weight of tetrachloroethane is 0.5~
1.5 is good.

The EVOH resin (A) used in the present invention preferably has an ethylene content in the range of 20 to 60 moles, preferably 25 to 6 moles.
It is 5 morti. When the content of ethylene units is less than 20 moles, the melting point and decomposition point are close to each other, resulting in poor thermal stability and melt moldability. Moreover, if the content of ethylene units exceeds 60 molty, the gas barrier properties will be poor, which is not preferable. The EV
The saponification degree of OH is preferably 95 molt or more, preferably 9
It is 8 molti or more. If the degree of saponification is less than 95 molt, it is not preferable because it has poor thermal stability, tends to be colored during melt molding, tends to cause gels and fish eyes, and also deteriorates gas barrier properties.

Furthermore, the EVOH resin (A) of the present invention may be modified with other copolymerizable monomers within a range that does not impede the object of the present invention. Such modifying monomers include propylene, l-butene, 1-hexene, 4-methyl-1-pentene, acrylic ester, methacrylic ester, maleic acid, fumaric acid, itaconic acid, higher fatty acid ester, alkyl vinyl ether, N -(2-dimethylaminoethyl)methacrylamides or quaternized products thereof,
N-vinylimidazole or its quaternized product, N-
Examples include n-butoxymethylacrylamide, vinyltrimethoxysilane, vinylmethyldimethoxysilane, and vinyldimethylmethoxysilane.

The present invention is Cal EvOH resin (A) JISK6760
Melt index y, (M I ) measured under the conditions of temperature 190 ° C. and load 216 Qf using the method described in , is 0.1.
~50F/10 minutes preferably 0.5~30t/1
0 minutes, especially 0.5-20? /10 minutes is preferable.

If the MI is less than 0.1 f/10 minutes, the fluidity during melt molding will be poor, the extrusion load and injection load will increase, and high-speed continuous operation will be hindered, and even worse,
This is undesirable as it tends to cause gel and fish eyes. Furthermore, if the MI exceeds 502/10 minutes, not only will the drop strength and impact strength of the molded container decrease, but also the amount of EVOH injected into each mold in a multi-piece molding machine will become unstable, making it difficult to mold a homogeneous container. To make matters worse, the thickness distribution of the EVOH in the axial direction of the multilayer injection molded preform becomes uneven, and the thickness distribution of the EVOH in the direction perpendicular to the axis also becomes thicker in the mouth part of the preform. The appearance of the mouth tends to become cloudy, which is undesirable.

It is important that the thermoplastic resin (B) to be blended with the EVOH resin (A) used in the present invention satisfies the following formula (1), and metal-containing polyester thermoplastic resins are examples of those that satisfy this formula. It will be done.

l≦MI (B) / MI (A)≦100
...(1) Such MI (A) / MI (B)
If it is less than 1, delamination that causes impact on the molded container is likely to occur. If MI(A)/MI(B) is greater than 100, the thickness distribution of the EVOH composition layer will be uneven during co-injection molding. I don't like Tonashi. A suitable range is 2≦M I (B
) / MI (A)≦80. Also EVOH (A
), when a saponified ethylene-vinyl acetate copolymer copolymerized with a vinylsilane compound is used, the impact resistance is further improved. The amount of copolymerization of the vinyl silane compound is 02 to 0.0002 mole, and if the amount of copolymerization is more than 02 mole, the resin easily gels and cannot be used. On the other hand, at 0.0002 molt or less, there is no significant difference in impact resistance against delamination compared to a material containing no vinyl silane compound.

Regarding the blend ratio of EVOH (A) and thermoplastic resin (B), it is good to have 5 to 40 parts by weight of thermoplastic resin (B) per 100 parts by weight of EVOH (A), preferably 7 parts by weight.
~30 parts by weight. If the blended amount of the resin (B) is less than 5 parts by weight, delamination ζ is likely to occur due to the impact of the molded container. In addition, if the amount exceeds 40 parts by weight, the gas barrier properties deteriorate, which is undesirable.As a preferred example of the metal-containing thermoplastic polyester used in the present invention, AJ, Cr is added to the polyester composed of a dicarboxylic acid component and a glycol component. .

One or more elements selected from the group consisting of Sn, Ge, and St in an amount of 0.1 to 100 moles of the dicarboxylic acid component.
A modified polyester containing 5 moles of I&-1' is obtained. Among these, M and Cr are preferable as the metal elements because they provide a large adhesive force, and M is particularly preferable. Further, if the content is less than 0.1 mol, the effect may not be sufficiently expressed, whereas if the content is more than 5 mol, undesirable phenomena such as gelation and coloring of the polymer will occur. In the present invention, these elements include embodiments in which these elements are mixed in polyester as compounds containing these elements, and further embodiments in which these elements are present in a state of being chemically bonded to polyester molecules, but the latter is preferable because high adhesive strength can be obtained. As a method for bonding the above-mentioned elements to polyester, there can be mentioned a method in which a compound of the above-mentioned element (particularly preferably a metal ester, a chelate compound, an organic acid salt, etc.) is added during polymerization of polynistyl, and the polymerization is carried out. For example, examples of the AJ compound include aluminum acetylacetonate, aluminum ethoxide, aluminum propoxide, and reaction products of these compounds and monocarboxylic acids. Examples of Cr compounds include chromium acetylacetonate or chromium monocarboxylate; examples of Sn compounds include tetraethyl stanate, tetraprobylstanate, tetraptyl stannate, or reaction products of these with monocarboxylate; and Ge. Examples of the compound include germanium dioxide, and examples of the Si compound include methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, and diphenyldimethoxysilane. Particularly preferred are aluminum acetylacetonate, aluminum ethoxide, and aluminum propoxide. It is preferable to add these compounds to the polyester polymerization reaction system after the polyester polymerization reaction is almost completed and at 230° C. or lower. The additive can be added by dissolving it in a diol, or by dissolving it in a monocarboxylic acid or its ester to prevent gelation of the polymer during polymerization. The dicarboxylic acid component constituting the thermoplastic polyester containing these elements includes aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid * naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl-4,4 dicarboxylic acid, and sulfuric acid. acids, malonic acid, succinic acid, geltanic acid, adipic acid,
Examples include aliphatic dicarboxylic acids such as pimelic acid, corkic acid, azelaic acid, and sepacic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and one or more of these can be used. In addition, as glycol components, ethylene glycol, 1.3-propanediol, 1,4-butanediol, 1.5-bentanediol, 1.6-hexanediol, 1.9-nonanediol, diethylene glycol, triethylene Examples include glycol, nato aliphatic glycol, and alicyclic diol such as cyclohexanediol and cyclohexane dimetatool, and one or more of these can be used. Furthermore, trivalent or higher carboxylic acids or alcohols can also be used if the food is eaten in small quantities. Preferably,
Examples of dicarboxylic acids include terephthalic acid, isophthalic acid,
Adipic acid is used, and as the diol, ethylene glycol and diethylene glycol are used. The intrinsic viscosity of the obtained thermoplastic polyester was 0. s Odl/
It is preferably 9 or more, and more preferably 0.60 dll.
f or more is preferable. The intrinsic viscosity here refers to 3
Value measured at 0°C ○ The method of blending resin (A) and resin (B) is not particularly limited.
) and then using the triblend pellets, and a method in which the triblend pellets are passed through a Banbury mixer-one-screw extruder or a twin-screw extruder to be pelletized again and dried. Further, during blending, it is free and effective to add antioxidants such as hindered phenols, hindered amines, and metal soaps, ultraviolet absorbers, or colorants within a range that does not impede the purpose of the present invention.

A container precursor (parison) having a multilayer structure is usually produced using a molding machine with two injection cylinders, and the molten polyethylene terephthalate and EvOH resin compositions are placed in a single mold in one mold clamping operation, and the injection cylinders are injected into each cylinder. This can be achieved by alternately or/and simultaneously injecting in concentric nozzles with shifted timing. For example, the PES that was injected earlier may be injected into the inner and outer surfaces of the EvoH layer.
It is obtained by a general method of forming a bottomed parison in which the inner layer is completely encapsulated by the outermost and outermost PES layers, such as by injecting the composition and/or PES one after another to form an intermediate layer, and is particularly limited by equipment. It's not a thing. In addition, the multilayer parison is heated directly to 75 to 150°C in a warm state or with a heating element such as a block heater or an infrared heater, and then
After being sent to a stretch blowing process and stretched 1 to 5 times in the vertical direction, it is blown 1 to 4 times with compressed air, etc.
The S or/and EVOH composition is uniaxially or biaxially stretched to obtain a multilayer polyester stretch-blown container. The heating and stretching step is not particularly limited in terms of equipment either.

By the way, as a means to further improve the impact deformability of the co-injection stretch-blown container, the above-mentioned thermoplastic polyester resin 1 is used.
00 parts by weight, 1 to 2 parts of metal-containing thermoplastic resin (B)
It is more effective to use a resin blended with 0 parts by weight, that is, to blend the thermoplastic resin (B) with both PES and EVOH. If the amount of resin (B) added to PES is less than 1 part by weight, the improvement effect is small and the amount added is 2 parts by weight or less.
If the amount is more than 0 parts by weight, the strength of the bottle will decrease and the appearance of the bottle will be poor, which is undesirable.

Whether or not heat treatment is applied to the stretch blow container O has a large influence on the impact delamination of the multilayer bottle, and it is desirable that the following formula (n) be satisfied.

(Tp −20) 〉Tc＞TB −・=
(1) If Tc is larger than 'rP-20, the outermost layer PES
The strength of the bottle becomes poor, probably because the water softens and the stretching orientation deteriorates. On the other hand, when Tc is lower than TB, no improvement in the impact delamination properties of the multilayer container is observed. Heat treatment time is 1-1
The heat treatment method is not particularly limited, but in general, the method of increasing the mold temperature during the blowing process, the method of heat treatment by heating the mold again under pressure, or the method of heat treatment using hot air, heat, etc. Examples include a method of heat treatment with a medium. In addition, when taking out a hot bottle after heat treatment, methods include rapidly cooling the heating mold or heating medium, or placing the bottle in a cooling mold again and cooling it under pressure in the cooling mold.

The structure of the blow container of the present invention uses two types of resins, PES and EVOH compositions, and the innermost and outermost PES layers are completely covered with an intermediate layer containing one or more layers of the EVOH composition or one or more layers each of the EVOH composition and PES. Generally, PES/EVO)I composition/PE51PES/Ev
Examples include OH composition/PES/PES, PES/EVOH composition/PES/EVOH composition/PgS, and the like.

Regarding the thickness of the parison, the total thickness is 2~s, u, EVO
The total thickness of the H composition layer is 10 to 500μ, and generally EVOI (the thinner the composition layer, the fewer the number of EVOH composition layers, the closer the EVOH composition layer is to the outer layer side, the closer the position of the EVOH composition layer is to the outer layer surface. The closer to
~3m, and can be used depending on the purpose. Further, the total thickness of the EVOH composition layer at this time is 2 to 200μ, preferably 5 to 100μ.

The present invention will be further explained below with reference to examples, but the present invention is not limited in any way by these examples.

Fl, Examples Example 1 Polyethylene terephthalate (PET) with an intrinsic viscosity of 0.71 was used as the thermoplastic polyester resin, and EV
The OH resin composition has an ethylene content of 32 moles, a saponification degree of 99.6%, and an MI(A) (melt index of 19).
0℃, 2160F) 1.3 f710 minutes, 8 points (MP
(A)) 181°C 17) Thermoplastic resin (B) made by blending and pelletizing 80 parts by weight of 6.12 nylon with 100 parts by weight of AJ-containing polyester prepared by the method described below with respect to 100 parts by weight of EVOH (A) ((MP
(B)) is 160°C and MI(B) is 80 f7
10 minutes) 20 parts by weight were triblended, pelletized at 220°C using a 40 mm twin screw extruder, and then dried under reduced pressure at 80°C for 16 hours. MI (B)/MI (A) at this time
) -46 degrees, seal MP (B) -80℃<MP (
A) It was -181°C. Using these resins, a co-injection stretch blowing machine (50-HT type 750
(12 pieces removed), PET side extruder tip temperature 27
0℃, EVOH side extruder tip temperature 200℃, PET and E
VOI (hot runner block part 260 where
Co-injection stretch blow molding was carried out in "C", and the average thickness of the body part was 90μ of inner layer PET, middle layer EvOH composition layer 2 (L,
A multilayer co-injection blow molded bottle with c+, outer layer PET 190μ was obtained. At this time, the adhesive strength (T-type peel strength) of the bottle body was as small as 309/1 o+u width. The length of the mold is 50mm so that impact delamination is likely to occur in the body of this bottle.
Orchid x horizontal 15U1 thickness 1. Omum, 2. Ors
s and 4. I added the unevenness of Ow. When the multilayered container was filled with water and repeatedly dropped from a height of 1 m under normal pressure with the body horizontally, delamination occurred on the 15th time. Also C
Place 2 where it was repeatedly dropped under pressure of 4 gas Vol with O2
Delami occurred on the seventh occasion.

In addition, when stretch-blowing this container from the parison, the blow mold temperature was set to 120°C and heat treatment was performed for 30 seconds. In the delamination test described above, delamination occurred at the 28th time when filled with normal pressure, and 50 times when filled with CO2 pressurized gas. No delamination occurred even after being dropped, and it was confirmed that the impact delamination property was improved by heat treatment.

By the way, the A71-containing polyester resin (B) used in Example 1 was a polyester obtained by the following method. That is, 300. 200ff of hexylene glycol is added to the polymerization apparatus, which is equipped with a nitrogen gas introduction tube, a stirrer, and a cooling tube into a y+l three-bottle flask! /, aluminum isopropoquine 0.20 mol, caprylic acid 0.10 mol, p
-oxybenzoic acid 0.30 mol, acetylacetone 0,
The aluminum compound obtained by adding 20 mol of bis-3-hydroxyethyl terephthalate (649) and adipic acid (36. ! IM,
Add 15.5f of ethidiethylenel and 14.9r of diethylene glycol and react at 200°C for 4 hours. Add 25μ of tributyl phosphate! , 0.52 mol of the above aluminum compound was added to 100 mol of the dicarboxylic acid component in terms of aluminum atoms, along with 40% of antimony trioxide, and the mixture was heated to 275°C while raising the temperature to 260°C.
The polymer was polymerized for 90 minutes under reduced pressure of 11jHf.

The intrinsic viscosity of this resin is 0.6Ldt/? The glass transition temperature was -5°C.

Example 2 In Example 1, the co-injection molding conditions were changed so that the average thickness of the container body was 1@ from the inside: PET 90 μ/EVOH composition 10 p/PET 100 p/EVOH composition 1
A bottle with a 2-layer and 5-layer structure of 0 μ/PET 90 μ was obtained. When the container was filled with normal pressure water, delamination occurred on the 14th time, and CO
In the case of pressurized filling of two gases, delamination occurred at the 23rd time. Further, when the heat treatment was carried out in the same manner as in Example 1, no delamination occurred at the 22nd time under normal pressure, and no delamination occurred even after being dropped more than 50 times with CO2 pressure filling.

Example 3 The same procedure as in Example 1 was conducted using a polyester composition obtained by blending 10 parts by weight of resin (B) into pellets with 100 parts by weight of the polyester resin. As a result, delamination occurred in the container after the 17th filling with normal pressure water, and delamination occurred after the 45th filling with pressurized water.It was found that blending resin (B) with polyester resin improved the impact delamination property. Ta.

Example 4 The resin (B) used in Example 1 was added to the same polymerization apparatus as that used in Example 1, and bis-17-hydroxyethyl terephthalate 647, isophthalic acid 4.6f, sebacic acid 242, EG30r, and Into a solution containing 40 mg of antimony oxide and reacting at 200°C for 4 hours, the same aluminum compound used in Example 1 was added in an amount of 0.52 mg per 100 moles of dicarboxylic acid component in terms of aluminum atoms.
mol, and further added 25μ of tributyl phosphate to 250
Raise the temperature to 270°C, then gradually reduce the pressure to 270°C.
C, and the intrinsic viscosity obtained by polymerizing for 100 minutes under a reduced pressure of 0.1 + uHf is 0.72 dll? , glass transition temperature 15MP 165℃, MI 5.51/10 min EVO
HK change implementation 1+! It was carried out in the same manner as I1. As shown in Table 1, the container was a good bottle with excellent impact resistance.

Example 5 The same procedure as in Example 4 was conducted using the composition shown in Table 1.

The performance of the obtained bottle is as shown in Table 1.

Example 6 E V OH (A) used in Example 1 was modified to have a C2H4 content of 32 mol%, a degree of saponification of 99.4%, a vinyltrimethoxysilane of 0.02 mol%, a melt index (MI(
A) 190°C, 2160f) The same procedure as in Example 1 was carried out except that the temperature was changed to 1.5 r for 710 minutes. As shown in Table 1, the result was a good container with greatly improved impact resistance.

Comparative Example 1 EVO containing no thermoplastic resin (B) in Example 1
The procedure was carried out in the same manner as in Example 1 using H resin.

As a result, delamination occurred in the container after the second drop when the container was filled with normal pressure water, and delamination occurred on the fifth time when the container was filled with CO2 pressurized gas. In addition, when a delamination test was conducted on a heat-treated bottle as in Example 1, delamination occurred on the first drop when filled with normal pressure water, and delamination occurred on the third drop when filled with CO2 pressurized gas, indicating that the heat treatment effect was not observed. I couldn't.

Comparative Example 2 Using the same polyester resin, polyester-polyamide resin (B), and EVOH resin (A) as in Example 1, PET700μ/resin (B) 1 was produced by a three-type, five-layer coextrusion pipe method.
00 p/EVOH (A) 180 p/Resin (B)
After molding a multilayer pipe of 100μ/1600μ PET, the pipe was cut into 10 boxes and heated using a parison molding machine to form a bottomed parison having a mouth and a bottom. The parison was applied to a cold parison heating stretching blowing device to create a 750 ml container.

The adhesive strength (T-peel) of the body of this container is 250? 7
Although the adhesion was relatively good with a width of 10 ms, delamination occurred after three drops during filling with water, and lamination occurred seven times during filling with CO24gasVol pressurized water and pressurized water filling.

Comparative Example 3 Same polyester resin and EVOH composition as Example 1 (
Using a blend of EVOH (A) and resin (B),
A multilayer pipe of PET 800μ/EVOH composition 180μ/PET 1700μ was obtained by a two-type three-layer coextrusion pipe method.

The pipe was molded in the same manner as in Comparative Example 2 to obtain a multilayer plastic container. The adhesive strength of the body of this container is 10? /
It was small, with a width of 10 IIIJ, and only one drop occurred when filling with water, and five times when filling with CO2 under pressure. Although the cause of this is not obvious, it can be seen that co-injection molding with the combination of resin compositions is effective in preventing impact delamination.

Comparative example 4 The same procedure as in Example 1 was conducted using the composition shown in Table 1.

The obtained container performance is shown in Table 1.

Margin G0 Below Effects of the Invention According to the present invention, it is possible to obtain a co-injection stretched multilayer plastic container with greatly improved impact resistance and delamination properties.

Patent applicant RiRashi Co., Ltd.

Claims (5)

[Claims] (1) Consisting of inner and outer surface layers and an intermediate layer of thermoplastic polyester (D), and the intermediate layer has an ethylene content of 20 to 6
A metal-containing polyester thermoplastic resin (B) that satisfies the following formula (I) based on 100 parts by weight of a saponified ethylene-vinyl acetate copolymer (A) with a saponification degree of 0 mol% and vinyl acetate component of 95% or more. ) A co-injection stretch blow container comprising a layer of composition (C) containing 5 to 40 parts by weight. 1≦MI(B)/MI(A)≦100...(I) [
However, MI (A): EVOH (A) melt index (2160 g, 270 °C) (g/10 minutes) MI (B): Melt index of resin (B) (2160 g, 270 °C) (g / 10 minutes)] (2) The co-injection stretch-blown container according to claim 1, wherein the co-injection stretch-blown container is heat-treated at a temperature represented by the following formula (II). (T_P-20)>T_C>T_B...(II) [However,
T_P: Thermoplastic polyester T_C: Heat treatment concentration of blow container (°C) T_B: Melting point or softening point of resin (B)] (3) The co-injection stretch-blown container according to claim 1, wherein the thermoplastic polyester (D) is a composition containing 1 to 20 parts by weight of the resin (B) per 100 parts by weight of the thermoplastic polyester. (4) a thermoplastic polyester in which the resin (B) contains 0.1 to 5 moles of one or more elements selected from the group consisting of Al, Cr, Sn, Ge, and Si per 100 moles of the dicarboxylic acid component; Alternatively, the co-injection stretch blow container according to any one of claims 1 to 3, which is a thermoplastic polyester containing the element in a state bonded to a polyester molecule. (5) EVOH (A) is a saponified ethylene-vinyl acetate copolymer containing vinylsilane compound units,
A co-injection stretched multilayer blow container according to any one of claims 1 to 4.