JPS6344436A - Oriented multilayer plastic vessel and manufacture thereof - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a stretched multilayer plastic container.
More particularly, the present invention relates to a stretched multilayer plastic container that exhibits a combination of excellent gas barrier properties, glabella peel resistance, and mechanical properties.

(Conventional technology) Polyethylene terephthalate has excellent moldability and is capable of biaxial molecular orientation, making it a lightweight product with excellent impact resistance, rigidity, gas barrier properties, light weight, and transparency. It has come to be widely used as plastic containers, especially beverage pins. However, the gas permeability of these polyester bottles is still not negligible compared to glass bottles.1 For example, when filled with carbonated drinks such as cola, the shelf life is said to be about 3 months at most.

On the other hand, polyamide has superior sparring properties compared to 4 polyesters, and utilizing this property, a multilayer plastic container has been proposed in which polyester is used as the inner and outer surface layers and polyamide is used as an intermediate layer.

(Unexamined Japanese Patent Publication No. 61-108542) (Problems to be Solved by the Invention) However, adhesion between a polyester layer and a polyamide layer is not always easy, and good adhesion is not possible in an unstretched state. Even the adhesive described above has the disadvantage that it easily peels off at the adhesive interface when molecular orientation is imparted by stretching.

For example, copolyamide adhesives and copolyamide adhesives that have been proposed for joining polyester and polyamide all have the above-mentioned tendency, and are still not fully satisfactory as adhesives for stretched multilayer plastic containers. It's not something you get.

Therefore, the present invention includes an adhesive layer that can firmly bond polyethylene terephthalate and polyamide both in an unstretched state as well as in a stretched state, and has gas barrier properties and
It is an object of the present invention to provide a multilayer plastic container that has excellent delamination resistance, particularly blister resistance, impact resistance, rigidity, and even transparency.

(Means for Solving the Problems) According to the present invention, from the inner and outer surface layers made of polyester, the intermediate layer made of polyamide, and the sulfonic acid group-containing copolyester layer provided between the surface layer and the intermediate layer, A stretched multilayer glass container is provided.

Further, according to the present invention, a sheet or a plastic sheet having a multilayer structure comprising an inner and outer surface layer made of polyester, an intermediate layer made of polyamide, and a sulfonic acid group-containing copolyester layer provided between the surface layer and the intermediate layer. A method for expanding a stretched multilayer plastic container is provided, which comprises forming the reform into a container shape under stretching conditions.

(Function) The present invention is superior in that even when a structure formed by laminating a sulfonic acid group-containing copolyester as an adhesive layer/a polyester layer and a polyamide layer is subjected to stretch molding, no peeling occurs between the eyebrows. This is based on the unexpected finding that adhesive strength is maintained.

Table 1 below shows that an unstretched I-lyethylene terephthalate film (thickness: 400 μm) and an unstretched metaxylylene group-containing nylon film were prepared using various conventionally known adhesives and the sulfonic acid group-containing copolyester adhesive used in the present invention. (thickness: 100 μm), the adhesive strength of this laminated film, and the adhesive strength of a biaxially stretched film obtained by biaxially stretching this laminated film twice in the longitudinal direction and twice in the transverse direction. shows.

Table 1 1 Urethane adhesive 230g 15g
2 Copolyamide type) 320g 18
N3 Copolyester type “) 2909 28
gning 4) 4 Polyester amide type 9209
1) In the case of urethane adhesive, peeling is due to cohesive failure of the adhesive 2) Adhesive strength is nylon 6/nylon 66 copolymer (caprolactam concentration is 917%) / IJ ethylene terephthalate and adhesive interface Show strength.

3) Terephthalic acid (20 mol width), isophthalic acid (60 mol width), succinic acid (20 mol qb) as dibasic acids
, a copolyester with a glass transition temperature of 35° C. using butylene glycol as the glycol, and adhesive strength indicates the adhesive strength at the interface between nylon and adhesive.

Umbrella 4) Polycondensation of N,N'-bis(p-carxybenzoyl)hexamethylenediamine and hexane-1,6-diol after transesterification reaction has a melting point of 2
Adhesive strength with polyesteramide at 65°C indicates the adhesive strength between the nylon and adhesive interface.

Umbrella 5) Sulfonic acid group-containing W-7'Jf used in Example 1 described below of the present invention! Adhesive strength of U ester indicates the adhesive strength between the nylon and adhesive interface.

Rate 6) Cut the sample into a rectangle with a width of 15 m, and cut the sample into a rectangle with a width of 100 m.
Shows the T-peel adhesive strength measured at a peel rate of min (
(Unit: g/15 width).

According to the results in Table 1 above, the adhesives of samples 1 to 4 were:
Although the adhesive strength in the unstretched state is slightly high, the adhesive strength decreases significantly after stretching, whereas the sulfonic acid group-containing copolyester of the present invention (Sample 5) shows a very high adhesive strength after stretching. It is clear that the degree of decrease in adhesive strength is significantly small and that samples 1 to 4 exhibit greater adhesive strength even after stretch molding.

The sulfonic acid group-containing copolyester used in the present invention is
It has a chemical structure in which the main chain is composed of repeating ester units and a sulfonic acid group is bonded to this main chain. Therefore, it is presumed that this adhesive not only bonds extremely strongly to polyethylene terephthalate, but also forms a strong chemical bond between the sulfonate and polyamide.

Furthermore, although polyamide is a polymer that is more difficult to stretch and mold than polyester, in the present invention, polyamide is sandwiched between inner and outer surface layers of I-lyethylene terephthalate, and between the two is a t-sulfonate. It is believed that by strongly bonding with the copolyester having the groups, stretch molding is possible and strong adhesive strength is maintained even after stretch molding.

(Operations and Effects of the Invention) According to the present invention, strong adhesive strength is maintained between the polyester layer and the polyamide layer even after stretching and forming, and as a result, even when the container is subjected to a drop impact, peeling between the eyebrows does not occur. Furthermore, even when filled with contents such as carbonated drinks and beer, problems such as blisters occurring at the joint between the polyester layer and the polyamide layer are effectively eliminated. .

Furthermore, polyamide with excellent gas barrier properties is provided as an intermediate layer, and the polyester layer is molecularly oriented by stretching, so it has excellent gas barrier properties, anti-glabella peeling properties, impact resistance, rigidity, and even transparency. A multilayer plastic container with excellent properties is provided.

(Description of Preferred Embodiments of the Invention) Adhesive The sulfonic acid group-containing copolyester used in the present invention generally has a main chain skeleton composed of ester repeating units and a sulfonate group bonded to this main chain skeleton. means a copolyester consisting of Of course, this adhesive may consist of the above-mentioned co-/IJ ester alone, or may be a blend of the above-mentioned copolyester and a normal polyester containing no sulfonic acid groups. In the present invention, copolyester is used in the above-mentioned meaning.

The concentration of sulfonate groups in the copolyester used in the present invention is preferably in the range of 1 to 520 mmol, particularly 5 to 300 mmol, per 100 g of adhesive. If the value is lower than the above range, the adhesion with the polyamide is insufficient, while if the value is higher than the above range, the adhesion with the polyester is insufficient.
ff There is a tendency for defects to occur in the thermal stability of the polyester itself.

As the sulfonate, alkali metal salts such as sodium salts, potassium salts, and lithium salts are suitable, but alkaline earth metal salts such as calcium salts and magnesium salts, and zinc salts are particularly prohibited.

In order to incorporate units having sulfonate groups into the polyester backbone, a fraction containing sulfonate groups may be used as part of the dibasic acid component and/or diol component for forming the polyester.

Generally, it is preferable to use a dibasic acid component containing a sulfonic acid group.

Suitable examples of such components include sodium 3,5-di(force/l/〆xy)benzenesulfonate, potassium 3,5-di(calgoxy)benzenesulfonate, and potassium 3,5-di(kalgoxy)benzenesulfonate.
Examples include magnesium carboxy)-4zenesulfonate and functional derivatives thereof, such as esters with methyl alcohol, ethyl alcohol, ethylene glycol, and the like.

Sono et al., sodium sulfosuccinic acid, sodium sulfoterephthalic acid, 4-sodium sulfonaphthalene-2,
Examples include 7-dicarboxylic acids and lower alcohol esters thereof.

The dibasic acids constituting this copolyester include benzenedicarboxylic acids such as terephthalic acid and isophthalic acid,
Other aromatic dicarboxylic acids such as naphthalene dicarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sepacic acid, dodecanedicarboxylic acid; or alicyclic dicarboxylic acids such as hexahydroterephthalic acid. Examples of diol components include ethylene glycol, propylene glycol, butanediol, diethylene glycol, neopentyl glycol,
Aliphatic diols such as hexanediol: cyclohexanediol, xylylene glycol, bisphenol A,
Examples include cyclic glycols such as bisphenol F.

In the copolyester used in the present invention, terephthalic acid accounts for at least 50 moles, especially at least 85 moles of the total dibasic acid component, excluding those introduced as sulfonic acid metal base-containing units, and terephthalic acid accounts for 50 moles or more of the total diol component. It is preferable to use ethylene glycol in a molar proportion of 85 or more, particularly 85 or more.

The copolyester used should have a molecular weight sufficient to form a film.

Polyester The polyester used in the present invention usually contains 50 or more moles of ethylene terephthalate structural units, preferably 70 moles or more.
It is a polyester obtained from an alkylene glycol containing 2 to 4 carbon atoms and an aromatic dicarboxylic acid. As the alkylene glycol, ethylene glycol is mainly used, but in addition to ethylene glycol, for example, 1,3-f ropanediol, 1,4
-Butanediol can be used in an amount as long as it satisfies the content of the above-mentioned ethylene terephthalate structural units. In addition, as the aromatic dicarboxylic acid, terephthalic acid is mainly used, but in addition to terephthalic acid, for example, isophthalic acid, fumeric acid, naphthalene dicarboxylic acid, etc. It can be used in limited quantities. Among them, polyethylene terephthalate is particularly preferred for practical purposes.

The intrinsic viscosity [η] (value measured at 25°C in a phenol-tetrachloroethane mixed solvent (weight ratio 1/1)) of the polyester is usually 0.5 to 1.5 dl/g, preferably 0.6 to 1.5 dl/g. 1.2 dl/11, melting point is usually 21
The temperature is 0 to 265°C, preferably 220 to 260°C, and the glass transition temperature is usually 50 to 120°C, preferably 60 to 100°C.

The polyester may contain a nucleating agent, an inorganic filler,
Appropriate amounts of various additives such as lubricants, slip agents, antiblocking agents, stabilizers, antistatic agents, antifogging agents, and pigments may be blended.

Polyamide The polyamide used in the present invention includes aliphatic, aromatic, and araliphatic diamines, aliphatic, and aromatic dicarboxylic acids, aliphatic, aromatic, and araliphatic aminocarboxylic acids, or lactams thereof. /+3 amides or copolyamides created from mixtures can be used.

Such polyamides are known per se and include oxygen,
From the viewpoint of gas barrier properties against carbon dioxide gas, etc., homopriamides, copolyamides, or blends thereof in which the number of amide groups per 100 carbon atoms in the polyamide is in the range of 3 to 30, particularly 4 to 25. It is preferable to use

Examples of suitable homopolyamides are: Ricapramide (Nylon 6) Bori-ω-Aminohebutanoic acid (Nylon 7) Poly-ω-
aminononanoic acid (nylon 9) polyundecaneamide (
Nylon 11) Polylaurinlactam (Nylon 12)
I-lyethylenediamine adipamide (nylon 2,6)?
Litetramethylene adipamide (nylon 4.6) polyhexamethylene adipamide (nylon 6.6) polyhexamethylene dodecamide (nylon 6.10) polyhexamethylene dodecamide (nylon 6.12) These include octamethylene azinamide (≠Iron 8,6) I ridecamethylene azinamide (nylon 10.6), polydodecamethylene sepacamide (nylon 10.8), and the like.

Examples of suitable copolyamides include caprolactam/laurinlactam copolymer, caprolactam/hexamethylene diammonium adipate copolymer, lauryl lactam/hexamethylene diammonium azide copolymer, hexamethylene diammonium azobate/hexamethylene. Examples include diammonium sepacate copolymer, ethylene diammonium acyl)/hexamethylene diammonium azide copolymer, caprolactam/hexamethylene diammonium adipate/hexamethylene diammonium sepacate copolymer, and the like. can.

These homopolyamides and copolyamides can also be used in the form of so-called blends, for example blends of polycaprolactam and polyhexamethylene adipamide, blends of polycaprolactam and caprolactam/hexamethylene diammonium adii-14 polymer. etc. can be used for the purpose of the present invention.

Also, Japanese Patent Publication No. 1156/1983, Publication No. 57/1983
Publication No. 51, Special Publication No. 50-5753, Special Publication No. 50
As described in JP-A-10196 and JP-A-50-29697, metaxylylene diamine, or metaxylylene diamine and diamine 3
Mixed xylylene diamine containing para-xylylene diamine having 01 or less and α,ω-aliphatic radical having 6 to 10 carbon atoms? It is also possible to use an aromatic polyamide containing at least 70 moles of a structural unit formed from phosphoric acid in its molecular chain.

Furthermore, an aromatic radical containing metaxylylene diamine, or metaxylylene diamine and a mixed xylylene cyanine containing para-xylylene diamine having a mole ratio of 30 or less in the diamine, and isophthalic acid at 30 or more mole, preferably 40 or more mole? An aromatic polyamide containing at least 70 moles of a structural unit formed from phosphoric acid in its molecular chain can also be used.

Furthermore, metaphenylene diamine and/or
An aromatic polyamide containing 30 molar or more, preferably 40 molar or more of rough phenylene diamine and isophthalic acid can also be used.

The molecular weight of these 4-lyamides can be used without any particular restriction as long as it is generally within the range that allows film-forming ability, but when 1 gram of polyamide is dissolved in 98% sulfuric acid xoocc and measured at 20 ° C. relative viscosity (ηr
eL ) is 0.2 to 3.5, especially 0.3 to 3.0
It is generally desirable that If the relative viscosity is higher than 3.5, the moldability of the preamide will be poor, and if the relative viscosity is lower than 0.2, the moldability of multilayer plastic containers or preforms for molding the containers will deteriorate. Mechanical strength becomes inferior.

The polyamide may contain various additives, such as nucleating agents, inorganic fillers, lubricants, slip agents, anti-blocking agents, stabilizers, antistatic agents, antifogging agents, and pigments, which are blended into conventional polyamides as necessary. An appropriate amount of the agent may be blended.

The main part of the container of the present invention is made of plastic that allows for a multilayer structure. This multilayer structure has a five-layer structure consisting of polyester layer/sulfonic acid group-containing copolyester layer (adhesive layer)/thiamide layer/sulfonic acid group-containing M copolyester layer (adhesive layer)//reester layer. .

Furthermore, if necessary, a nine-layer structure consisting of a polyester layer, /the adhesive layer/-the lyamide layer/the adhesive layer/the polyester layer/the adhesive layer//the lyamide layer/the adhesive layer//the lyester layer. It may be.

The thickness of the jt' IJ ester layer is usually 3 to 40 mm.
The thickness of the polyamide layer is usually 1 to 350 μm, preferably 2 to 200 μm, and the thickness of the sulfonic acid group-containing copolyester layer is usually 0.5 μm. 350 trm, preferably 2 to 200 trm. The ratio of the total thickness of the aromatic d-lyester layer to the thickness of the polyamide layer is 2:1
Preferably it is in the range from 100:1 to 100:1, especially from 4:1 to 50:1.

At least one polyester layer, preferably all polyester layers, more preferably all polyester layers and polyamide layers of the multilayer plastic are stretched.

The stretching is carried out in at least one axial direction, preferably in two axial directions perpendicular to each other.

From the viewpoint of strength and gas barrier properties, it is preferable that the film be stretched in two axial directions. The stretching ratio is usually 1.1 to 10 times, preferably 1.2 to 8 times, and more preferably 1.5 to 7 times. Furthermore, the multilayer plastic can also be heat set depending on its intended use.

The multilayer plastic in the present invention has a polyester layer and a polyamide layer in contact with each other by a sulfonic acid group-containing copolyester layer, which improves the stretchability of the sulfonic acid group copolyester layer itself and has an affinity for adhesion to the polyester. Since the strength and affinity adhesion with polyamide are large, even if the multilayer plastic is stretched in one or two axes, it can be stretched sufficiently according to the degree of need without causing delamination.

Manufacturing method of container The stretched multilayer plastic container of the present invention, which has the above-mentioned excellent features, is based on the second invention of the present invention, namely, inner and outer surface layers made of polyester, an intermediate layer made of polyamide, and the surface layer. A stretched multilayer plastic container manufacturing method comprising forming a multilayered sheet or preform comprising a sulfonic acid group-containing copolyester layer between an intermediate layer and a container shape under stretching conditions. can be manufactured.

In the manufacturing method of the present invention, when manufacturing a container from a multilayered sheet having the above structure, the container is manufactured by a sheet stretch molding method which is known per se, except that a multilayered sheet having the above structure is formed. can be manufactured.

For example, an extruder equipped with a multi-layer multi-die is used to form a sheet of the above-mentioned multi-layer structure plastic of the present invention, and the sheet is stretched by l-axis or bi-axis, or by vacuum forming or compressed air. Molding method.

A container of a desired shape can be manufactured by stretch-molding by a method such as a sheet blow molding method, a drawing method, a drawing and ironing method, a compression molding method, or the like.

In addition, the multilayer structure plastic sheet is produced by separately molding a polyester, a polyamide, and a sulfonate-containing copolyester into a sheet or film, and then combining them into a single sheet or film.
It can also be produced by axially or biaxially stretching, or by laminating the layers to have the structure of the present invention without stretching, and then heat-pressing them.

In the manufacturing method of the present invention, when manufacturing a container from a multilayered preform having the above-mentioned structure, a method known per se can be used, except that the multilayered structure and structural material of the preform are specified in the present invention. Containers can be manufactured by molding methods.

For example, a multilayer parison can be formed by using three or more extruders to extrude the three types of molten resins used in the present invention in a multilayer die in a laminated form as described above. , one end of the parison is closed to produce a bottomed parison (preform), heated at a predetermined temperature for a predetermined time in a mold that fits the desired shape of the container, and then the axis of the cylinder is tightened with a stretch rod. There is a method in which the material is stretched in the (vertical) direction and then stretched in the horizontal direction in a mold using compressed air. The preform may be molded by injection molding.

The stretching conditions when preparing a container by stretch-molding a sheet or preform vary depending on the resin used, but it should be stretched at a temperature that is above the glass transition temperature and below the crystallization initiation temperature of the resin used. It is preferably stretched in at least one axial direction, preferably in two axial directions, and the stretching ratio is usually 1.1 to 10 times, preferably 1.2 to 8 times,
More preferably, it is stretched 1.5 to 7 times so that the resin layer of the resulting container has molecular orientation.

Applications The multilayer plastic container of the present invention can be used for liquid or yeast-like foods and beverages, such as beer and other low-malt beverages, sake, fruit liquors such as whisky, shochu, and grape wine, and alcoholic beverages including various cocktails such as gin fizz: cola. −, Cysy,
Various carbonated drinks, including plain soda, etc.; Straight juices, such as lemon juice, orange juice, plum juice, grape juice, and strawberry juice; and fruit juice drinks, including processed fruit juice drinks, such as nectar: tomato g-
Sugar, cane juice drinks containing various vegetable juices; Synthetic drinks and vitamin-fortified fruit juices containing sugars such as sugar or fructose, citric acid, coloring agents, flavorings, etc., or vitamins added as necessary. Drinks; lactic acid bacteria drinks; for example, Shi, Tsuyu, So/C, vinegar, Mil), dressing, mayonnaise, ketchup, edible oil, miso, lard,
Seasonings such as ketchup; Favorites such as tofu, jam, putter, and margarine; Also, liquid medicines, agricultural chemicals, cosmetics, fragrances, and detergents; Also, ketones such as acetone and methyl ethyl ketone: normal hexane, normal heptane Aliphatic hydrocarbons such as didichlorohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; chlorine-containing compounds such as carbon tetrachloride, ethane tetrachloride, and ethylene tetrachloride; or various higher fatty acids ; Gasoline, kerosene, petroleum benzine, heavy oil, thinner, grease, silicone oil, light oil, machine oil; Useful as a container.

Example 1 As a polyester, the intrinsic viscosity at 30'C is 1.
06 polyethylene terephthalate (PET) was used as polyamide, and the relative viscosity at 25°C was 2.1.
Polymethaxylylene aji A? PAM was used as a sulfonic acid group-containing copolyester containing 5,200 mmol of sodium sulfonate group per 10OI of the polymer.
Using copolyester (AD), the multilayer structure and the thickness ratio of each layer are PET (outer layer) /AD/PAM/AD/PET (
A multilayer preform with inner layer) = 1010.2/'110.215 was manufactured by a multilayer extrusion method. A bottle having an internal volume of 15QQllI7 and a weight of 59y was manufactured from this preform by a stretch blow molding method.

Drop test (conditions) Fill a bottle with water, fill it slightly below eye level, add baking soda and citric acid to make the gas volume 4.0, leave it at room temperature for 24 hours, and then drop it 2m on a concrete floor. The product was dropped vertically and horizontally from a height of

The water bottle of the present invention did not crack when dropped vertically or horizontally, and no delamination occurred at all.

Gas permeability The oxygen permeability Q02 (37°C) of the bottle of the present invention is 1.3
cc/m”・day-atm.Reference PET
Single layer QO2 (37℃) is 5.9 cc/m2 a
day*atm.

Comparative Example 1 The same polymer as in Example 1 was used, except that the sodium sulfonate group-containing copolyester was not used,
2 types 3 layers (PET/PAM/PET = 10.2
/115.2 thickness ratio) A tor of the same size was cut from the preform in the same manner.

A drop test and a gas permeability measurement were conducted on this Comparison + f) Le under the same conditions as in Example 1. As a result of the drop test, both vertical and horizontal drops ) Delamination occurred over almost the entire surface of the tile.

In addition, the oxygen permeability QO2 (37℃) of Torr is 4 for one comparison.
．． It was 1 cc/m" day-atm.

Claims (4)

[Claims] (1) A stretched multilayer plastic container comprising inner and outer surface layers made of polyester, an intermediate layer made of polyamide, and a sulfonic acid group-containing copolyester layer provided between the surface layer and the intermediate layer. (2) The container according to claim 1, characterized in that at least the polyester layer is stretched in at least one direction and has molecular orientation. (3) The container according to claim 1, characterized in that the content of sulfonic acid groups in the sulfonic acid group-containing copolyester is 1 to 520 mmol per 100 g of said copolyester. (4) A sheet or preform with a multilayer structure consisting of inner and outer surface layers made of polyester, an intermediate layer made of polyamide, and a sulfonic acid group-containing copolyester layer provided between the surface layer and the intermediate layer is stretched under stretching conditions. 1. A method for producing a stretched multilayer plastic container, the method comprising forming a stretched multilayer plastic container into a container shape.