JPH08295002A - Multilayer hollow container - Google Patents

Abstract

PURPOSE: To develop a multilayer hollow container with high luster, minimized luster irregularity and an outer surface layer best suited for printing. CONSTITUTION: This multilayer hollow container is composed of an outer surface layer consisting of a resin composition which contains each 500 to 5000ppm of polyethylene glycol with a molecular weight of 100 to 500, or monoester of fatty acid and sorbitan with a number of carbons of 8 to 22, and further, 500 to 5000ppm of sorbitol, if necessary, added to high-density polyethylene resin with a density of 935kg/m<3> or higher and a melt index(MI) of 2 to 50g/10min. and an inner layer of polyethylene resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer hollow container, and more particularly to a multi-layer hollow container useful in various fields in which cosmetics containers such as shampoo and rinse are used.

[0002]

2. Description of the Related Art In recent years,
As a container for shampoo, conditioner, cosmetics, food, medicine, etc., a container by a blow molding method is often used. As materials for manufacturing these hollow containers,
Conventionally, polyvinyl chloride resin has been frequently used, but such materials generate harmful chlorine gas when incinerated,
Due to poor recyclability, the use of polyolefin resins was started. Among them, polyethylene resin is
It has the advantages that no harmful gas is generated and the molding cost is lower than polypropylene. However, the polyethylene resin has the drawbacks of poor surface gloss and poor printability, and its field of use has been limited.

On the other hand, some proposals have been made so far regarding the high-density polyethylene resin. For example, Japanese Patent Application Laid-Open No. 55-71732 describes a polyethylene resin having a relatively good glossiness, but has a drawback that uneven glossiness is conspicuous and printability is deteriorated. JP-A-62-179941 describes a polyethylene resin having no problem in printability, but uneven gloss is conspicuous and glossiness is insufficient. Further, Japanese Patent Application Laid-Open No. 1-216838 discloses a technique in which a lubricant such as oleic acid amide is added to a high-density polyethylene resin to improve gloss unevenness, but printability deteriorates and glossiness is deteriorated. The point was also insufficient. From this, there is a strong demand for the development of a material using a polyethylene-based resin, which has high gloss and less uneven gloss and can be used in the field of cosmetics such as shampoo and conditioner, and has excellent printability. Was there. Therefore, an object of the present invention is to develop a container having high gloss, less uneven gloss, an outer surface layer having excellent printability, generation of no harmful gas, and excellent reusability. is there.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object. As a result, a multi-layer hollow container having an outer surface layer formed of a resin composition obtained by containing a specific polyethylene glycol or a specific ester in a high density polyethylene resin and an inner layer formed of a polyethylene resin. However, it has been found that the above object can be achieved. The present invention has been completed based on such findings.

That is, the present invention provides a high-density polyethylene resin having a density of 935 kg / m ³ or more and a melt index (MI) of 2 to 50 g / 10, and a molecular weight of 100 to 5000.
Polyethylene glycol or monoester of sorbitan with fatty acid having 8 to 22 carbon atoms, 500 to 5000
It is intended to provide a multilayer hollow container having an outer surface layer formed of a resin composition contained in an amount of ppm and an inner layer formed of a polyethylene resin. The present invention also provides a multi-layer hollow container characterized in that the resin composition comprises the high-density polyethylene-based resin containing a sorbitol-based nucleating agent in an amount of 500 to 5000 ppm. Hereinafter, the multilayer hollow container according to the present invention will be described in more detail.

The multi-layer hollow container according to the present invention is a container having at least two layers, an outer surface layer formed of a specific resin composition and an inner layer formed of a polyethylene resin. Therefore, first, the resin composition forming the outer surface layer in the multilayer hollow container of the present invention will be described. The resin composition used for the outer surface layer of the present invention is mainly composed of a high-density polyethylene resin. This high-density polyethylene resin has a density of 935 kg / m ³ or more, preferably 9
It is in the range of 50 to 970 kg / m ³ , and the melt index (MI) is 2 to 50 g / 10 minutes, preferably 4 to 2
It is in the range of 0 g / 10 minutes. When the density is less than 935 kg / m ³ , the outer surface of the container is likely to be scratched and the slip property is deteriorated. On the other hand, in the range of 950 to 970 kg / m ³ , the surface hardness is the same as that of general polyethylene for blow molding, so that a more preferable container can be obtained. MI
When it is less than 2 g / 10 minutes, so-called melt fracture occurs when melt-extruding while operating the extruder at a high rotational speed, and the outer surface is remarkably roughened to lower the glossiness. On the other hand, if it exceeds 50 g / 10 minutes, the outer layer is likely to have uneven thickness, resulting in uneven gloss. On the other hand, 4 ~
If it is in the range of 20 g / 10 minutes, molding can be performed without using a special uneven thickness adjustment or a molding machine, so that a container can be manufactured with low productivity and high productivity.

The high density polyethylene resin used in the present invention may be either a homopolymer of ethylene or a copolymer of ethylene and another α-olefin. Although various kinds of α-olefins are used, α-olefins having 3 to 20 carbon atoms are preferably used, and specifically, for example, propylene and butene-
1, pentene-1, octene-1,4-methylpentene-1, vinylcyclohexane and the like can be mentioned. This α-olefin may be used alone or in combination of two or more. When the high-density polyethylene resin is a copolymer, the content of α-olefin unit is preferably 0.3 to.
It is 1.5% by weight. The method for producing the above high-density polyethylene resin is not particularly limited, but a Ziegler type catalyst comprising a transition metal component such as titanium or vanadium and an organic aluminum compound, a Phillips type catalyst using chromium or the like, or zirconium, titanium or hafnium. It can be obtained by polymerizing (copolymerizing) ethylene or the like as a raw material with a metallocene catalyst comprising a transition metal component such as the above and a cocatalyst component such as an aluminoxane or an ionizing agent.

The polyethylene glycol used in the present invention has an average molecular weight of 100 to 5,000, preferably 10
It is in the range of 00 to 4000. When the average molecular weight is less than 100, the sticky feeling on the outer surface of the container becomes large, and when the average molecular weight exceeds 5,000, the effect of improving the uneven gloss of the high density polyethylene is small and the effect of improving the printability is small.
On the other hand, when the average molecular weight is in the range of 1,000 to 4,000, the texture of the outer surface of the container is good, and the effect of improving the gloss unevenness of the high-density polyethylene and the effect of improving printability are large, which is preferable. This polyethylene glycol is added to high density polyethylene resin at 500 to 5000 ppm, preferably 1000
Contained in an amount of ˜3000 ppm. Content is 500p
If it is less than pm, the effect of improving the unevenness of gloss of high-density polyethylene and the effect of improving printability are small, and the content is 5000 p.
When it exceeds pm, the glossiness is lowered. On the other hand, the amount of polyethylene glycol is 1000 to 3000
When it is in the range of ppm, the effect of improving the unevenness of gloss and the effect of improving the printability are further increased, which is preferable. The method for producing the polyethylene glycol is not particularly limited, and those produced by any method can be used.

The ester used in the present invention has 8 carbon atoms.
It is a monoester compound consisting of ~ 22 fatty acids and sorbitan. This monoester compound is preferably a monoester having only one ester bond between a fatty acid and sorbitan. If there are two or more ester bonds,
It is not preferable because the effect of improving printability is small. The fatty acid that constitutes this ester compound has 8 to 2 carbon atoms.
2, preferably fatty acids having 12 to 18 carbon atoms are used, but these may be a mixture of fatty acids. Specific examples of fatty acids include saturated fatty acids such as stearic acid and lauric acid, and unsaturated fatty acids such as oleic acid and erucic acid. The above monoester compound is added to high density polyethylene resin in an amount of 500 to 5000 pp.
m, preferably in the amount of 1000 to 3000 ppm. When the content is less than 500 ppm, the effect of improving the uneven gloss and printability of the high-density polyethylene is small, and when the content exceeds 5000 ppm, the glossiness is lowered. On the other hand, when the amount of the monoester compound is in the range of 1000 to 3000 ppm, the effect of improving gloss unevenness and the effect of improving printability are greater, which is preferable.

Further, in the present invention, a sorbitol type nucleating agent is preferably used as a nucleating agent used as necessary, and specifically, for example, dibenzylidene sorbitol,
Examples thereof include ditrilidene sorbitol. When a nucleating agent is used, the high-density polyethylene-based resin contains the sorbitol-based nucleating agent in an amount of 500 to 5000 ppm, preferably 1000 to 3000 ppm. When the content is less than 500 ppm, there is no effect on improving the glossiness of the outer surface layer, and when the content exceeds 5000 ppm, bleeding out to the outer surface is large and the wettability to the surface is deteriorated, and the printability is deteriorated. It is not preferable because it damages. on the other hand,
The amount of this sorbitol-based nucleating agent is 1000 to 3000 pp
When it is in the range of m, the effect of improving the unevenness of gloss and the effect of improving the printability are greater, which is preferable.

The outer surface layer of the present invention is a resin composition containing the above-mentioned high-density polyethylene resin as a main component and further containing the above-mentioned components, but the method of incorporating the above-mentioned respective components is not particularly limited. That is, at the time of producing the high-density polyethylene-based resin, it may be contained by adding the above-mentioned components, or may be contained by adding it in a masterbatch together with the antistatic agent and the pigment. Further, the order of addition may be arbitrary, and the apparatus for addition is not particularly limited.

Further, the above resin composition may optionally contain
It is also possible to add various additives and compounding agents that are commonly used in the field of pearl pigments such as mica and polyethylene resins. These additives and compounding ingredients include phenol-based or phosphorus-based antioxidants, heat stabilizers,
Examples thereof include an anti-ultraviolet agent, a neutralizing agent, an antistatic agent, a fluidity improving agent, an optical brightening agent, and an organic / inorganic colorant. The layer ratio of the outer surface layer in the multilayer hollow container may be appropriately determined in consideration of the purpose of use of the container, size, required performance such as mechanical strength, generation of recycled resin, recovery, etc. In the container of the present invention, the thickness is preferably 5 to 30%, more preferably 10 to 20%.
Is the range of the layer ratio.

Next, the inner layer of the multi-layer hollow container of the present invention will be described. The inner layer in the present invention is formed from a polyethylene-based resin and may be used without particular limitation as long as it is a resin. Specifically, in addition to a homopolymer of ethylene, a copolymer of ethylene and α-olefin, a high density polyethylene,
Low-density polyethylene, linear low-density polyethylene, a mixture thereof, or the like can be used. It is also possible to add additives and compounding agents such as an antioxidant, a heat stabilizer, an anti-UV agent, a neutralizing agent, an antistatic agent or a fluidity improving agent to the polyethylene resin. In addition, the layer ratio in such a multi-layer hollow container of the inner layer is determined by the purpose of use of the container,
It may be appropriately determined in consideration of required performance such as size and mechanical strength, generation and recovery of recycled resin, and the like. In the container of the present invention, the thickness is preferably 70 to 95.
%, And more preferably in the range of 80 to 90%.

The multi-layer hollow container of the present invention is a container having at least two layers of the outer surface layer and the inner layer described above, but may have other layers as required. For the other layers,
Examples thereof include an intermediate layer formed between the outer surface layer and the inner layer, and such an intermediate layer may be formed of any resin other than polyethylene resin. Further, the intermediate layer may be a single layer or may be formed of two or more layers. The materials for these intermediate layers include
It is also possible to add and use additives such as an antioxidant, a heat stabilizer, an ultraviolet protective agent, a neutralizing agent, an antistatic agent or a fluidity improving agent, and a compounding agent.

When the multilayer hollow container of the present invention is manufactured, it is manufactured by the blow molding method using the above materials. The manufacturing method is not particularly limited, and can be manufactured using a conventionally known multilayer blow molding machine. For example, the manufacturing method is as follows. After the polyethylene resin is heated and melted by a plurality of extruders, the resin is extruded as a molten parison from a multilayer die. Next, this parison is sandwiched between molds, and air is blown into the parison to manufacture the multilayer hollow container according to the present invention. still,
As a manufacturing method of the hollow container, not only the direct blow molding method but also an injection blow molding method, a rotary blow molding method or the like can be used.

[0016]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The glossiness measurement, gloss unevenness and printability in Examples and Comparative Examples were carried out by the following measuring methods. [Measurement of Glossiness: According to JIS-Z8741] A test piece was cut out from the side surface of a hollow-molded 500 ml round bottle and measured in the resin flow direction. As a measuring machine,
The incident angle was 60 degrees using a gloss meter made by Nippon Denshoku Industries Co., Ltd. [Gloss unevenness] The gloss unevenness is the length Am of the highly glossy surface with respect to the specific range length 117 mm of the outer surface of the hollow molded container.
The ratio of m was measured as the gloss range. Gloss range (%) = [(Amm) / 117 mm] × 100 Therefore, the larger the value of the gloss range, the less the uneven gloss of the outer surface of the container. [Printability] The printability was evaluated by the contact angle when a test piece was cut out from the side surface of a hollow-molded 500 ml round bottle and a water drop was dropped on the test piece. As a measuring instrument, FACE automatic interfacial tension meter P manufactured by Kyowa Interface Science Co., Ltd.
Using a DZ type, the temperature was measured at 23 ° C. Here, the smaller the contact angle, the better the wettability with water, and the better the printability.

Example 1 A high-density polyethylene having a density of 967 kg / m ³ and an MI of 5.1 g / 10 was charged into a melt extruder (diameter 26 mm) manufactured by Toyo Seiki Seisakusho. Using this extruder, polyethylene glycol having an average molecular weight of 1500 was melt-added at 190 ° C. so that the content was 2500 ppm, to obtain a resin composition. The obtained resin composition is used for a multilayer molding machine having a diameter of 45 mm (Tahara Seisakusho Co., Ltd.)
1) for each of the cylinder, head, and die
At a set temperature of 90 ° C and a mold temperature of 25 ° C, the rated capacity is 5
It was molded into a round bottle type multi-layer container of 00 ml. This round bottle type multi-layer container has a layer ratio of the outer layer to the inner layer of 15:85.
And is a double container having a basis weight of 40 g. When the gloss, gloss range and contact angle of the obtained molded container were measured, the gloss was 50%, the gloss range was 70% and the contact angle was 7%.
It was 8 degrees. From this, it can be seen that the molded container obtained has excellent gloss, uneven gloss, and good printability.

Example 2 In the same manner as in Example 1, high density polyethylene was charged into an extruder, and at 190 ° C., polyethylene glycol having an average molecular weight of 3000 was contained, and the content thereof was 2500 ppm.
Was melted and added to obtain a resin composition. The obtained resin composition was molded into a round bottle type multi-layer container in the same manner as in Example 1, and the glossiness, gloss range and contact angle were measured. The glossiness was 47%, the gloss range was 68%, and the contact angle was 68%. Corner 80
It was degree. From this, it can be seen that the molded container obtained has excellent gloss, uneven gloss, and good printability.

Example 3 In the same manner as in Example 1, high-density polyethylene was charged into an extruder and sorbitan monostearate was melt-added at 190 ° C. to a content of 2500 ppm to obtain a resin composition. Obtained. The obtained resin composition was molded into a round bottle type multi-layer container in the same manner as in Example 1 and the glossiness, gloss range and contact angle were measured.
%, The gloss range was 65%, and the contact angle was 81 degrees. From this, it can be seen that the molded container obtained has excellent gloss, uneven gloss, and good printability.

Example 4 In the same manner as in Example 1, high density polyethylene was charged into an extruder, and at 190 ° C., the content of polyethylene glycol having an average molecular weight of 1500 was 2500 ppm and the content of ditrilydene sorbitol was 1500 ppm. Each was melt-added as described above to obtain a resin composition. The obtained resin composition was molded into a round bottle type multilayer container in the same manner as in Example 1, and the glossiness, gloss range and contact angle were measured. The glossiness was 62%, the gloss range was 70%, and the contact was 70%. Corner 8
It was once. From this, it can be seen that the molded container obtained is excellent in gloss unevenness, printability, and further excellent in gloss.

Example 5 In the same manner as in Example 1, high density polyethylene was charged into an extruder, and at 190 ° C., the content of polyethylene glycol having an average molecular weight of 3000 was 2500 ppm, and the content of ditrilydenesorbitol was 1500 ppm. Each was melt-added as described above to obtain a resin composition. The obtained resin composition was molded into a round bottle type multilayer container in the same manner as in Example 1, and the glossiness, gloss range and contact angle were measured. The glossiness was 67%, the gloss range was 67%, and the contact angle was 67%. Corner 8
It was twice. From this, it can be seen that the molded container obtained is excellent in gloss unevenness, printability, and further excellent in gloss.

Example 6 In the same manner as in Example 1, high density polyethylene was charged into the extruder so that the content of sorbitan monostearate was 2500 ppm and the content of ditrilidene sorbitol was 1500 ppm at 190 ° C. Each was melt-added to obtain a resin composition. The obtained resin composition was molded into a round bottle type multilayer container in the same manner as in Example 1,
When the glossiness, the gloss range and the contact angle were measured, the glossiness was 60%, the gloss range was 62% and the contact angle was 83 degrees.
From this, it can be seen that the molded container obtained is excellent in gloss unevenness, printability, and further excellent in gloss.

Comparative Example 1 The same high-density polyethylene as in Example 1 was molded into a round bottle type multilayer container similar to that in Example 1 without using the resin composition, and the glossiness, gloss range and contact angle were measured. As a result, the glossiness was 40%, the gloss range was 50%, and the contact angle was 78 degrees. The obtained molded container had insufficient gloss and uneven gloss.

Comparative Example 2 In the same manner as in Example 1, high-density polyethylene was charged into an extruder and melt-added at 190 ° C. so that the content of ditrilidene sorbitol was 1500 ppm to obtain a resin composition. It was The obtained resin composition was molded into a round bottle type multi-layer container in the same manner as in Example 1, and the glossiness, gloss range and contact angle were measured.
%, The gloss range was 53%, and the contact angle was 94 degrees. The obtained molded container had poor gloss unevenness and poor printability.

Comparative Example 3 In the same manner as in Example 1, high-density polyethylene was charged into an extruder and melted at 190 ° C. so that the content of ditrilydenesorbitol was 1500 ppm and the content of oleic acid amide was 2500 ppm. Addition was carried out to obtain a resin composition. The obtained resin composition was molded into a round bottle type multi-layer container in the same manner as in Example 1, and the glossiness, gloss range and contact angle were measured. Glossiness 50%, gloss range 67%, contact The angle was 97 degrees. The obtained molded container is
The printability was poor.

[0026]

The multi-layer hollow container of the present invention has an outer surface layer formed of a specific resin composition and an inner layer formed of a polyethylene resin, and thus has high gloss and less uneven gloss, and is suitable for printing. The container has an excellent outer surface layer, does not generate harmful gas, and has excellent suitability for recycling. Therefore, the multilayer hollow container of the present invention can be suitably used as a container in the field of cosmetics such as shampoo and rinse.

Claims (2)

[Claims] 1. A high-density polyethylene resin having a density of 935 kg / m ³ or more and a melt index (MI) of 2 to 50 g / 10, polyethylene glycol having a molecular weight of 100 to 5000, or a fatty acid having 8 to 22 carbon atoms and sorbitan. A multi-layer hollow container having an outer surface layer formed of a resin composition containing the monoester of 1. in an amount of 500 to 5000 ppm and an inner layer formed of a polyethylene resin. 2. The resin composition comprises a high density polyethylene resin and a sorbitol nucleating agent in an amount of 500 to 5000 p.
The multi-layer hollow container according to claim 1, wherein the multi-layer hollow container is contained in an amount of pm.