JPH01139347A - Tube container - Google Patents

Abstract

PURPOSE:To provide a tube container excellent in the property of preventing air-back, appearance, the preservation of contents and the flavor-barrier property, by forming a tube body of a laminate having an inner layer of olefin resin, an intermediate layer of a gas-barrier resin and an outer layer of olefin resin of an given composition. CONSTITUTION:A tube container 1 and at least the body portion 5 thereof consist of a laminate having an inner layer 7a of olefin resin, an intermediate layer 6 of a gas-barrier resin and an outer layer 7b of olefin resin. At least the outer layer 7b of the aforesaid olefin resins and preferably both of the inner and outer layers 7a and 7b have a composition of linear low density polyethylene and the other ethylene series polymer such as ordinary low density polyethylene, i.e. high pressure processed low density polyethylene in the weight ratio of from 80:20 to 30:70, preferably from 70:30 to 35:65, whereby the time required for return to the original tube shape after squeezing out the contents can be considerably extended and the air-back phenomenon can be effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a squeeze tube container used for packaging viscous materials, and more specifically to a squeeze tube container made of multilayer plastic that has outstanding airbag prevention properties. Regarding containers.

(Prior Art) Conventionally, squeeze containers have been used, for example, extruded tubes for storing highly viscous liquid products such as toothpaste, cosmetics, or foods, and viscous foods such as ketchup, mayonnaise, jam, and chocolate. Squeeze to squeeze out)
Bottles made of various flexible laminates are known.

Such plastic flexible laminates generally consist of an oxygen barrier layer made of saponified ethylene-vinyl acetate copolymer, nylon, etc. as an intermediate layer, and olefin resin layers such as polyethylene layered on both sides. It has become. When forming the duplex, these flexible laminated sheets are overlapped and bonded to form a cylindrical shape, and one end of this cylindrical body is provided with a threaded extrusion port formed by injection molding of resin. Consisting of continuous conical shoulders are glued together, and the other end of the cylindrical body is closed by fusion or the like. Further, when forming a squeeze bottle, the multilayer parison made of the above-mentioned laminated structure is hollow-molded in a split mold to form a bottle.

This squeeze tube container made of multi-layer plastic has excessively poor recovery properties, such as giving a certain pressure deformation and then returning to the original container shape when released, and for this reason, it is sealed with a lid after use. During restorage, a large amount of air is drawn into the container, resulting in the contents being degraded by the oxygen in the container, creating an air bag.

In order to prevent this air bag,
No. 23 discloses that the tube container includes at least one layer mainly composed of at least one oxygen barrier resin selected from the group consisting of ethylene-vinyl alcohol copolymer and polyamide, and a layer having an elastic modulus of 700 to 700. 90008
A modified layer having an elastic modulus EA lower than or equal to the elastic modulus EB of the oxygen barrier resin and higher than or equal to the elastic modulus Eo of the olefin resin between the layer and at least one layer mainly composed of an olefin resin in the range of g7 cm2. It is formed of a laminated structure provided with an adhesive intervening layer containing an olefin resin, and the layer mainly composed of an olefin resin has a thickness greater than the sum of the oxygen barrier property and the adhesive intervening layer, and has an olefin resin. The layer mainly composed of resin has an elastic modulus E. ,8g7
The product of cm2 and thickness to, cm is 9 to 170 Kg/
It is described that it should be within the range of cm.

(Problems to be Solved by the Invention) Although the airbag-preventing squeeze tube containers shown in the prior art are considerably improved in airbag-preventing performance compared to similar multilayer plastic duplex containers, The recovery time after deformation by pressing is shorter than that of the aluminum foil-plastic laminate type, which is unsatisfactory for the purpose of completely preventing airbags.

Therefore, an object of the present invention is to provide a squeeze-out duplex container made of multilayer plastic that has deformability suitable for the squeezing characteristics of the contents, extends the recovery time after pressure deformation, and has excellent airbag prevention properties as a result. is to provide.

Another object of the present invention is to provide a squeeze tube container that, in addition to the above characteristics, has excellent appearance characteristics before and during use, and also has excellent preservability and aroma retention of the contents. .

(Means for Solving the Problem) In a squeeze tube container in which at least the body is formed of a coextruded laminate of an olefin resin inner layer, a gas barrier resin intermediate layer, and an olefin resin outer layer, at least the outer layer of the inner and outer olefin resin layers is provided. is 80:2 of linear low density polyethylene and other ethylene polymers.
A squeeze tube container is provided comprising a composition containing a composition in a weight ratio of 0 to 3'O.

(Function) The squeezed tube container of the present invention has at least its body formed of a coextruded laminate of an olefin resin inner layer, a gas barrier resin intermediate layer, and an olefin resin outer layer. At least the outer layer, preferably both the inner and outer layers, are linear low density polyethylene (L-LDPE).
and other ethylene-based polymers such as ordinary low-density polyethylene, i.e., high-pressure low-density polyethylene (HP-LDPE), in a ratio of 80:20 to 3'O:70, especially 70:30 to 35.65. A notable feature is that the composition is composed of a composition containing a weight ratio of . That is, the present invention
When at least the outer layer, preferably both the inner and outer layers, of the multilayer tube container are composed of a blend of L-'LDPE and other ethylene polymers such as HP-LDPE, it is possible to restore the original shape after suppressed deformation. This is based on the knowledge that the time can be significantly extended, thereby effectively preventing the airbag phenomenon.

Conventionally, it has been thought that olefin resins with a low elastic modulus are suitable for the inner and outer olefin resin layers of multilayer plastic squeeze containers, and from this perspective, high-pressure low-density polyethylene (HP-LDPE) and ethylene-
Vinyl acetate copolymer (EVA) has been used. However, although HP-LDPE (1!1IEVA) does have a small elastic modulus, it still recovers to its original shape within a relatively short period of time due to its shape recovery (cushioning) properties. I couldn't escape this drawback.

In contrast, according to the present invention, L-LDPE and HP-L
It was discovered that when a composition prepared by blending DPE with other ethylene polymers at a specific blend ratio was used as the olefin resin layer, the air hack occurrence time was extended by 2 to 5 times. .

In the present invention, the fact that the recovery time after pressure deformation, that is, the air pack generation time is significantly prolonged by using a blend of L-LDPE and other ethylene polymers, is based on experimental results. The reason for this has not yet been elucidated. However, the present inventor estimates the reason as follows.

Linear low-density polyethylene has several characteristics not found in conventional high-pressure low-density polyethylene and low-pressure high-density polyethylene (HDPE).

That is, high-pressure low-density polyethylene has a molecular structure with long chain branches and is a single polymer of ethylene, whereas linear low-density polyethylene has a substantially straight-chain molecular structure and consists of ethylene and carbon. It consists of a copolymer with 4 to 8 α-olefins. On the other hand, low pressure high density polyethylene has a density (25°C) of 0.940 to 0.965 g/cm.
3, and its molecular structure has almost no short branched chains, whereas linear low-density polyethylene has a density in the range of 0.915 to 0.935 g/cm3, and its molecular structure has almost no short branched chains. - They differ in that they have short chain branches derived from olefins.

This linear low-density polyethylene (L-LDPE) is related to the chemical structure mentioned above, and compared to other olefin resins, such as high-pressure low-density polyethylene (Hp-LDPE) and high-density polyethylene (HDPE), They have differences in physical properties as shown in Table 1 below.

Table 1 Resin Elongation (*) Strength (Kg/cm) Melting point (1) I, -LDPE 850
300 106~122HP-LDPE
600 120
94~114HDPE 800
As shown in Table 1 above, 230 1+8 to 133 linear low density polyethylene has the characteristics of greater elongation, strength and toughness (product of elongation and strength) compared to other polyethylenes. , when deformed in the form of a film-like material, it has the property of being easily bent and deformed.

Thus, when linear low-grade polyethylene is contained in the surface layer of a squeezing container, bending deformation is likely to occur in the container wall when suppressed deformation is performed, and this bending deformation takes a long time to restore. It is estimated that the air pack generation time will be extended.

It is also important that the surface layer of the squeezing container used in the present invention contains linear low density polyethylene and other ethylene polymers in the above-mentioned ratio. That is, L-LDPE
If the amount of
If the amount exceeds the above range, the surface of the coextruded laminate tends to become rough, resulting in poor appearance and transparency.Furthermore, when suppressive deformation is applied, white streaks may appear at the bends. This tends to cause poor appearance characteristics and deterioration of gas barrier properties and fragrance retention properties.

(Preferred Embodiment of the Invention) Tube Container Nos. 1, 2 and 3 showing a specific example of the duplex container of the present invention
In the figure, this tube container consists of a tube body 1 and a lid 2, and the duplex body 1 has a threaded extrusion opening 3 integrally formed by hollow molding a multilayer parison, which will be described in detail later, and a screw opening 3 connected thereto. It has a flexible conical shoulder 4 and a cylindrical body 5.

In FIG. 3, which shows an enlarged cross-section of the wall of the multilayer parison constituting each of these parts, the body wall 5 includes an oxygen barrier thermoplastic resin layer 6, olefin resin layers 7a and 7b, and an intervening layer between these layers. It is composed of an adhesive intervening layer 8.

In FIGS. 1 and 2, this cylindrical body 5 has a cut edge 9 at which the facing inner layers 10, 10 of the body are overlapped and fused. , forming the bottom.

Each resin layer In the present invention, the olefin resin of at least the outer layer, preferably both the inner and outer layers, is composed of a blend of the aforementioned linear low density polyethylene and another ethylene polymer.

Comonomers in this linear low density polyethylene include butene-1, pentene-1,4-methylpentene-
1, hexene-1,2-methyl-butene-1, octene-1, and other α-olefins having 4 to 8 carbon atoms;
It is incorporated into the polymer chain in an amount of 3% to 15% by weight, in particular 3% to 15% by weight.

As other ethylene polymers, high-pressure low density polyethylene (LDPE) is advantageously used, but ethylene-vinyl acetate copolymers, especially those with a vinyl acetate content of 0.5
20% by weight of copolymers, ethylene-acrylic acid ester copolymers, ethylene-propylene copolymers, ionically crosslinked ethylene copolymers (ionomers), etc. can also be used.

The most suitable example of the oxygen barrier resin layer is an ethylene-vinyl alcohol copolymer, especially one containing 40 to 85 mol%, especially 50 to 80 mol% of vinyl alcohol alone. Such ethylene-vinyl alcohol copolymers consist of a combination of ethylene or a large portion of ethylene with minor components of other olefins such as propylene, and vinyl esters of lower fatty acids such as vinyl formate, vinyl acetate, and vinyl propionate. It is obtained by saponifying a polymer, particularly an ethylene-vinyl acetate copolymer, to a degree of saponification of 96% or more, particularly 99% or more.

Other examples of oxygen barrier resins include nylon resin,
Especially nylon 6, nylon 8, nylon 11, nylon 12, nylon 6.6, nylon 6.10, nylon 1
0.6 or nylon 6-6.6 copolymer.

The oxygen barrier resin can be used in the form of a so-called blend. For example, a blend of an ethylene-vinyl alcohol copolymer and a nylon resin can be used, and a blend of an ethylene-vinyl alcohol copolymer and a nylon resin can also be used. / or blends mainly composed of nylon and containing small amounts of other resins, such as polyethylene, ethylene-vinyl acetate copolymers, or ionomers, have an oxygen permeability coefficient of 5.5 x 1.
0-12'cc cm/cm2・sec-cmHg (
37°C, 0% RH) or less, especially 4.5 x 10-0-
If it is within the range of 12cc-7cm2·sec·cmHg or less, it can be used for the purpose of the present invention.

The inner and outer olefin resin layers and the gas barrier resin intermediate layer are generally adhesively laminated with an acid-modified olefin resin layer interposed as an adhesive layer. As acid-modified olefin resin,
The aforementioned high-density polyethylene, low-density polyethylene, medium-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, A. ethylenically unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, Itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, B ethylenically unsaturated carboxylic anhydride: maleic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, tetrahydrophthalanhydride A graft modified with acid, etc. is used, and the carbonyl group by acid or acid anhydride is 1 to 600 mmol/100g.
Resins, especially those containing 10 to 400 millimorphs in a concentration of 100 g resin, are particularly preferably used.

Layer Structure In the tube container of the present invention, the wall thickness of the final container wall is 0.
,17 to 1,0 mm, particularly preferably in the range of 03 to 0.7 mm. In addition, it is desirable that the thickness of the inner and outer olefin resin layers (TA) and the thickness of the gas barrier intermediate layer (T, ) be in a thickness ratio of TA: T, = 2: 1 to 201, especially 51 to 151. Layer thickness (Tc
) preferably satisfies a thickness ratio of TB:Tc=5:1 to 1.5, particularly 21 to 12.

Furthermore, a scrap resin composition produced as a by-product during the manufacture of the tubular container may be interposed between the inner and outer olefin resin layers and the adhesive.

In the tube container of the present invention, it is preferable that the entire container is formed of the above-mentioned coextruded multilayer laminate;
Only the body portion may be formed of a coextruded laminate, and the shoulder portion and the squeezing mouth portion may be formed of other resin.

(Effects of the Invention) According to the present invention, the olefin resin surface layer of the multilayer plastic tube container is formed of a blend of linear low-density polyethylene and other ethylene resin, thereby making it suitable for squeezing out the contents. While retaining its properties, the recovery time after pressure deformation was extended, and as a result, airbag prevention performance was significantly improved. This container has outstanding appearance characteristics, content preservation properties, and aroma retention properties before and during use.

(Example) The invention is illustrated in the following examples.

Example 1 An extruder for a gas barrier resin layer has a built-in screw with a diameter of 40 mm and an effective length of somm, and an adapter that has a built-in screw with a diameter of 35 mm and an effective length of 700 mm and a melt channel branched into two. Adhesive layer extruder equipped with diameter 65+nm, effective length 70
Using a multilayer extruder consisting of an extruder for olefin resin layers (inner and outer layers) equipped with a built-in screw of 0 mm and an adapter having two branched melt channels, and a die for symmetrical five-layer extrusion. , gas barrier
The middle layer is made of ethylene-vinyl alcohol copolymer (EVOH) with an ethylene content of 30 mol% as a plastic resin, and linear low-density polyethylene (LL-L) is used as an olefin resin.
DPE) and low-density polyethylene (LDPE) as the inner and outer layers, and between the middle layer and the inner and outer layers, high-density polyethylene (M-HDPE) with a carbonyl group concentration of 50 mmol/100 g is graft-modified with maleic anhydride. 3fi! with interposed as an adhesive layer! A five-layer molten parison is formed, and this parison is sandwiched between molds cooled to 10°C.
A multilayer duplex container with an internal diameter of 7 mm and a content of 180 g was obtained by blow molding at a blow pressure of 6 Kg/cm2.

The wall thickness of the body is 400μ, and the ratio of each layer is inner layer:adhesive layer:middle layer:adhesive layer:outer layer=10+0.5:2
:0.5 +10 was enough. The results are shown in Table 2.

Table 2 C, D, E, F...Examples A, B, G,
H...Comparative example *1...Weight ratio*2...The contents of the tube container are twisted! 18
It shows the time (minutes) it takes for the container to restore its original shape when 90g of the contents are squeezed out after filling 0g.

Example 2゜Similarly to Example 1, the ethylene content was 30 mol% (7
) EVOH as the intermediate layer, a blend of L-LDPE and LDPE as the inner and outer layers, and between the intermediate layer and the inner and outer layers, a linear low-density polyethylene with a carbonyl group concentration of 40 mmol/100 g modified by grafting with maleic anhydride ( M-L
-LDPE) Three types of five-layer tube containers were obtained.

This tube container has an internal capacity of 120 g, an internal diameter of 5 mm, a body wall thickness of 350 μm, and the ratio of each layer is inner layer: adhesive layer: middle layer: adhesive layer: outer layer = 10:
The ratio was 1:2:1:B.

The results are shown in Table 3.

Table 3 I, J, K...... Examples, M
Comparative Example *3 Ethylene-vinyl acetate copolymer with a vinyl acetate content of 8 mol% is used as the olefin resin for the inner and outer layers.

*4...After filling a tube container with 120g of wasabi paste and squeezing out 60g of the content, the time (seconds) until the content accumulated in the mouth and neck is returned to the inside of the container and a through hole is formed. ) is shown.

[Brief explanation of the drawing]

FIG. 1 is an external view of the tube package of the present invention, FIG. 2 is a sectional view of the tube package, and FIG. 3 is an enlarged sectional view of the multilayer parison wall. DESCRIPTION OF SYMBOLS 1... Tube body, 2... Lid, 3... Extrusion port with screw, 4... Shoulder part, 5... Body part, 6... Oxygen barrier resin layer, 7a, 7b.・・Moisture-resistant resin layer, 8・・
- Adhesive layer, 9... Edge portion, 1o... Inner view.

Claims (2)

[Claims] (1) In a squeeze tube container in which at least the body is formed of a coextruded laminate of an olefin resin inner layer, a gas barrier resin intermediate layer, and an olefin resin outer layer, at least the outer layer of the inner and outer olefin resin layers is made of linear low-density polyethylene, etc. 80:2 with ethylene polymer
A squeeze tube container comprising a composition containing a composition in a weight ratio of 0 to 30:70. (2) The squeezed tube container according to item 1, wherein the other ethylene polymer is high-pressure low-density polyethylene.