JP6511735B2 - Direct blow container - Google Patents

Description

  The present invention relates to a package suitable for containing viscous contents represented by ketchup and mayonnaise, and more particularly to a package whose inner surface is roughened.

  Plastic containers are widely used in various applications because they are easy to mold and can be manufactured inexpensively. In particular, a bottle-shaped olefin resin container formed by direct blow molding in which the inner surface of the container wall is formed of an olefin resin such as low density polyethylene is viscous such as ketchup from the viewpoint of easy squeezing out the contents It is suitably used as a container for containing slurry-like or paste-like contents.

  In the case of a bottle containing viscous content, the bottle is stored in an inverted state in order to quickly discharge the content or to use it completely without leaving it in the bottle. There are many. Therefore, when the bottle is inverted, it is desirable that the viscous contents do not adhere to the inner wall surface of the bottle and drop quickly.

  In order to satisfy such a requirement, conventionally, the resin which forms the inner surface of the bottle has been dealt with by means such as blending a lubricant, but such means has a limit in improving the slidability, and the leap The reality is that such improvements have not been achieved.

From such a point of view, recently, means for forming a liquid film on the inner surface of the container has been proposed as a means for dramatically improving the slip property (see Patent Documents 1 to 3).
That is, if a liquid film is formed on the inner surface of the container, the contents of the container slide down on the inner surface of the container due to liquid-liquid contact, so the liquid that forms the liquid film is appropriately selected according to the contents. By doing this, it is possible to ensure extremely high slidability even to the viscous contents, and it is possible to dramatically improve the drainage.

By the way, when the sliding property to the contents is enhanced by the formation of the liquid film as described above, it becomes important to keep the liquid film stable so as not to come off from the inner surface of the container. As described also in 3, a means is adopted in which the inner surface of the container is a rough surface on which fine asperities are formed.
As means for making the inner surface of the container such a rough surface, for example, Patent Document 3 discloses a method in which fine particles such as silica are mixed with a resin forming the inner surface of the container to form the container. . Such means do not need to use a special mold or to perform processing such as roughening, which is extremely advantageous for industrial implementation.

  However, by blending fine particles with the resin that forms the inner surface of the container, the means for roughening the inner surface of the container limits the amount of liquid that can be retained on the surface, and the thickness of the liquid film is thin and uneven. There is a problem that it is difficult to stably exhibit the effect of improving the slipperiness of the liquid film by the liquid film, and it is necessary to improve the problem.

WO 2012/100099 WO 2013/022467 WO 2014/010534

Therefore, the object of the present invention is to form a liquid film having a sufficient thickness to stably exhibit the effect of improving the slipperiness with respect to the contents, particularly for a direct blow container suitably applied for containing viscous contents. It is an object of the present invention to provide a direct blow container in which the rough surface which can be formed is formed over the entire inner surface of the package.
Another object of the present invention is to provide a direct blow container in which a liquid film is stably held over the entire inner surface.

According to the present invention, the inner resin layer is formed by extrusion molding using the thermoplastic resin composition in which the particles for roughening are dispersed in an amount of 1 to 20 parts by mass per 100 parts by mass of the thermoplastic resin. Direct blow containers ,
The graining material for roughening has a bidisperse particle size distribution having at least two maximal peaks , and the bidisperse particle size distribution has a first maximal peak in the range of 0.2 to 6 μm and 8 to 8 It has a second maximum peak in the range of 100 μm, and the first maximum peak and the second maximum peak have an interval of 3 μm or more, and the peak intensity of the first maximum peak X And the ratio of the peak intensity of the second maximum peak Y (X / Y) is in the range of 0.1 to 10, and
The surface of the inner surface resin layer is formed by particles having a small particle diameter in the roughened particles overlapping with large irregularities formed by particles having a large particle diameter in the roughened particles. It has a fractal structured surface with small irregularities formed,
The direct blow container is characterized in that a liquid film of edible oil or liquid paraffin is coated on the fractal structure surface to improve the slipperiness of the contents contained in the container. Be done.

In the direct blow container of the present invention,
(1) The roughening particle is at least one selected from the group consisting of metal oxides, metal salts, and organic fine particles;
(2) The thermoplastic resin used to form the inner resin layer is an olefin resin,
Is preferred.

In the direct blow container of the present invention, the inner surface is formed of the resin composition in which the roughening particles are blended. That is, in the resin layer forming the inner surface of the container, the particles for surface roughening are distributed, and a rough surface is formed by the particles, but in the present invention, the particles for surface roughening are Those having a multidispersed particle size distribution are used. That is, the graining material for roughening has a particle size distribution showing at least two peak values, and roughly speaking, it is composed of a large diameter particle group and a small diameter particle group. In the direct blow container of the present invention in which the inner surface is formed of a resin composition containing roughened particles having such a polydispersed particle size distribution, the degree of surface roughening of the inner surface is the liquid to be coated on the surface On the other hand, it is possible to stably form a liquid film having a sufficient thickness to stably exhibit the effect of improving the slipperiness with respect to the contents.

  As described above, the direct blow container of the present invention can form a liquid film exhibiting slipperiness with respect to the contents thickly over the entire inner surface, and thus such liquid film prior to the filling of the contents. By providing the inner surface with the inner surface, it is possible to effectively exhibit the sliding property to the contents.

The figure for demonstrating the principle of roughening. The figure which shows the form of the direct blow container of this invention. FIG. 6 is a graph showing the particle size distribution of the roughening granules used in Example 1.

<Principle of surface roughening>
The principle of surface roughening using the surface- roughening particles in the direct blow container of the present invention will be described.

The direct blow container is extruded with a molding resin to form a tubular parison, and then one end of the parison is pinched off and closed, and then a blowing fluid such as air is injected into the parison. It manufactures by shape | molding in the form of a container by blow molding (stretching molding) supplied inside.
Referring to FIG. 1, when a tube-like parison is formed by extrusion using a resin composition containing grains for roughening, particles 3 are dispersed in the inside of parison wall 1. In this state, the shape of the particle 3 is not reflected on the wall surface, and hence the surface of the parison wall 1 is a smooth surface.
When the parison having such a structure is subjected to blow molding and shaped into the form of a container, the parison wall 1 is thinned by drawing by blow molding, and the container wall 5 obtained is obtained according to the degree of blow (stretching) It will be thinned. The shape of the particles 3 is reflected on the surface by the thinning by such blow molding (stretch molding), and the inner surface side of the container wall 5 becomes rough. That is, a desired liquid (slidability improving liquid) is coated on such an inner surface to form a liquid film for improving the lubricity.
In addition, as shown in FIG. 1, the outer surface side is not roughened, and the smooth surface is that the outer surface side is cooled in contact with a blow mold for shaping in a container shape. This is because the blow mold surface is transferred.

As understood from the above description, when the inner surface of the container is roughened by direct blow molding using a resin composition containing the roughening particles, the particle diameter of the particles 3 is roughened. It will greatly affect the form of That is, in the case of particles having a large particle size, a rough surface having a large roughness is formed, and in the case of particles having a small particle size, a fine rough surface having a small roughness is formed.
As shown in the below-mentioned experimental example, the maximum height PV of the surface formed when using the large diameter particle group having large particle diameter alone is the surface formed when using the small diameter particle group having small particle diameter alone It becomes large compared with the maximum height PV in. That is, in order to form large unevenness, it can be said that it is effective to use a large diameter particle group having a large particle diameter. However, in the case where the large diameter particle group is used alone, the number of projections in the convex portion decreases, and it is difficult to form a large number of small irregularities with small roughness. It can be said that it is extremely difficult to form a fractal-shaped structural surface in which small asperities are formed to overlap large asperities.
On the other hand, from the viewpoint of forming small irregularities, it is effective to use small diameter particle groups, and as shown in the below-mentioned experimental example, it is possible to increase the number of protrusions of convex portions by addition of small particle diameter particles. It is. However, it is difficult to form a large convex portion such as a large diameter particle group by the small diameter particle group alone, and it is extremely difficult to obtain a fractal-like structure surface in which small unevenness is formed by overlapping with large unevenness even with the small diameter particle group alone. It can be said that
Therefore, in the present invention, by using a particle having a particle size distribution showing at least two peak values as the particle, a rough surface having a large roughness is formed by particles having a large particle diameter in direct blow molding. And, by forming fine rough surfaces with small roughness by particles with small particle sizes, it is possible to obtain the hierarchical structural surface (fractal structure surface) having the above-mentioned different roughness.

In the case of roughening such roughening granules, the present invention is distinguished by the use of particles having a particle size distribution (bi-dispersed particle size distribution) exhibiting at least two peak values in the present invention. It is characterized in that by applying a lubricity improving liquid to this surface, a thick liquid film (that is, a large amount of liquid) of the liquid can be formed over the entire inner surface.
Although the reason why a thick liquid film can be formed by molding using a resin composition in which particles for surface roughening having such a polydispersed particle size distribution are blended is not exactly clarified, the present invention The following were estimated by the people.
That is, in the present invention, the rough surface formed by the particles of the large diameter particle group having a large particle diameter is combined with the surface having a small roughness formed by the particles of the small diameter particle group having a small particle diameter. A fractal structured surface is formed on which small irregularities are formed by overlapping the irregularities, so that the contact area between the liquid to be applied and the surface is large, and as a result, a large anchor effect is exhibited, The amount of liquid that can be held increases, and the thickness of the liquid film formed on the surface can be increased.

<Form of direct blow container>
The direct blow container of the present invention is generally in the form of a bottle, as shown in FIG. 2, and this bottle 10 has a neck 11 connected to the neck 11 via a screw 13 and a shoulder 13. It has the bottom part 17 which closes the lower end of the part 15 and the trunk | drum 15.

In the bottle 10, the inner surface of the stretch-formed portion (the shoulder portion 13, the body portion 15, and the bottom portion 17) is a rough surface formed of the roughening particles having the above-described double-dispersed particle size distribution.
In such a rough surface, the peak value of the bi-dispersed particle size distribution of the roughened particles is generally set such that the maximum height PV (height between peak and valley) is in the range of 4 to 50 μm. It is preferable that a large amount of liquid can be stably held throughout the rough surface. Here, the maximum height PV is a value formed by particles of the large particle diameter particle group having a large particle diameter among the roughening particles having the bidispersed particle size distribution.

  That is, prior to the filling of the contents, a lubricity improving liquid immiscible with the contents is applied to the inner surface of such a bottle 10 by spray coating or the like according to the type of the contents. After this, the contents are filled, and then a metal foil 19 such as aluminum foil is heat-sealed to the upper end opening of the neck portion 11 and a predetermined cap 20 is attached to be used as a packaging bottle. . In such a packaging bottle, the cap 20 is opened, the metal foil 19 to which the sealing material is applied is peeled off, and the container wall is taken out by squeezing the body wall 15 as necessary by tilting or inverting the bottle 10 Is done.

  In the resin composition for forming the inner surface of the bottle 10 described above, as a resin to which the granular material for roughening is blended, thermoplastic resin capable of being formed into the form of a bottle container, for example, polyester represented by polyethylene terephthalate And olefin resins, and in particular, from the viewpoint of being suitably used for forming containers, such as direct blow containers, filled with viscous fluid contents that are required to have improved slidability. It is formed of an olefin resin, in particular, low density polyethylene, linear low density polyethylene, medium or high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl 1-pentene and the like. Of course, random or block copolymers of α-olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and the like are also suitable, and are further disclosed in JP-A-2007-284066 and the like. It may be a cyclic olefin copolymer.

In general, inorganic fine particles, for example, fine particles of metal oxides such as silica, alumina, titanium oxide and the like, metal salts and the like are used as fine particles for surface roughening to be blended in the above-mentioned resin For example, organic fine particles obtained by polymerizing and curing polyfunctional acrylic monomers can also be used.
The inorganic fine particles are preferably subjected to a hydrophobization treatment to avoid moisture absorption and the like. Such hydrophobization treatment uses a hydrophobizing agent such as a silane compound, a siloxane compound, a silazane compound, a titanium alkoxide compound, etc., and a hydrophobic functional group such as a coupling alkyl group, an alkylsilyl group, a fluoroalkyl group or a fluoroalkylsilyl group It is carried out by modifying the surface of the inorganic fine particle with a group, (heating) mixing the inorganic fine particle and a hydrophobic substance such as a fatty acid, and coating the surface of the inorganic fine particle.

  In the present invention, the above-mentioned roughening granular material has a particle size distribution of a polydispersion type, and exhibits, for example, the particle size distribution shown in FIG. This particle size distribution is measured by a laser diffraction scattering method, and has a first maximum peak X on the small diameter side and a second maximum peak Y on the large diameter side.

In such a polydisperse particle size distribution, the first maximum peak X is in the range of 0.2 to 6 μm, and the second maximum peak Y is in the range of 8 to 100 μm . The distance d between the first maximum peak X and the second maximum peak Y is in the range of 3 μm or more .
That is, when the position of the first maximum peak X or the second maximum peak Y is out of the above range, the maximum height PV of the inner surface of the bottle 10 finally formed is from the above-mentioned range (4 to 50 μm) As a result, even if the limit holding amount of the slipperiness improving liquid decreases or the limit holding amount can be secured, molding defects such as generation of cracks on the inner surface of the bottle 10 tend to occur.
In addition, when the distance d between the first maximum peak X and the second maximum peak Y is too small, roughening due to double dispersion is not sufficiently exhibited, and the limit holding amount of the slipperiness improving liquid can be increased. It may be difficult.

  Furthermore, in the above particle size distribution, the ratio (X / Y) of the peak intensity (frequency) of the first maximum peak X to the peak intensity (frequency) of the second maximum peak Y is 0.1 to 10, In particular, the combined effect of the surface roughening is sufficiently exhibited that the intensity (frequency) of the minimum peak Z in the range of 0.1 to 5 and between the peaks X and Y is 20% or less It is suitable to form a large specific surface area and to increase the limit holding amount of the slip improving agent.

  In the above example, although the case where there are two maximum peaks is described as an example, for example, the smaller diameter side or the larger diameter than the small diameter maximum peak X as long as the effect of the rough surface complexing according to the present invention is not impaired. A maximum peak may further exist on the larger diameter side than the maximum peak Y of.

Furthermore, such particles for roughening are used in an amount of 1 to 20 parts by mass, particularly 3 to 10 parts by mass, per 100 parts by mass of the above-mentioned resin. If this amount is too small, it will be difficult to effectively roughen, and if it is too large, molding will be difficult.

The blending of the roughening fine particles into the above-mentioned resin is easily carried out by melt-kneading the resin and the granular material for roughening into the kneading section in the extruder.
At this time, it goes without saying that known additives may be added to the resin composition as long as the surface roughening is not affected.

  Further, the molding of the bottle 10 is carried out by melt-extruding the resin composition in which the granular material for roughening is blended to form a tube-like parison and then performing blow molding. As long as the inner surface is formed, it may be a multilayer structure in which another resin is laminated. For example, it is possible to form a multilayer structure in which a layer of a gas barrier resin such as ethylene vinyl alcohol copolymer is provided as an intermediate layer through a layer of adhesive resin, or burrs generated during molding of parisons and bottles. It is also possible to provide a layer of regrind in which scraps of the like are mixed with virgin resin as an intermediate layer.

In the above manufacturing process, blow molding to obtain the bottle 10 from the parison is carried out in a manner known per se at a temperature above the glass transition temperature (Tg) of the resin.
Furthermore, in blow molding for forming the bottle 10, in general, for example, the thickness of the body is about 200 to 800 μm so that desired strength, flexibility, possibility, squeeze property, etc. can be exhibited. The circumferential stretching ratio is set to about 2 to 4 times.

  The liquid to be applied to the inner surface of the bottle 10 obtained as described above spreads throughout the inner surface and forms a liquid film of uniform thickness from the interface with the resin for forming the inner surface described above. It is desirable that the tension be 20 mN / m or less, in particular 15 mN / m or less, and particularly 10 mN / m or less. Among such liquids having good wettability, the type of contents to be finally filled Depending on the content, those which exhibit good slipperiness without being mixed with the contents are selected.

  For example, a viscous fluid having a viscosity of 100 mPa · s or more at 25 ° C. is generally suitable as the content contained in the bottle 10, and in the present invention, such a viscous fluid is preferably used. Even when the bottle 10 is filled, a predetermined liquid is appropriately selected to form a liquid film, so that the content is prevented from adhering to the inner wall surface of the bottle, and it is discharged cleanly or until the end It can be used up. That is, by forming a liquid film on the inner surface of the bottle 10, the viscous content which is the content will be discharged in liquid-liquid contact, and the viscous content will not contact the inner surface of the container, The viscous contents can be quickly discharged cleanly without adhering to the inner surface of the container 60.

  Such viscous contents may be in the form of an emulsion or non-emulsion, and specific examples thereof may be mayonnaise, ketchup, various sources (Uster sauce, medium-density sauce, etc.), Examples thereof include aqueous paste, honey, mayonnaise, mustard, dressing, jam, cosmetic solution such as chocolate syrup, yogurt and milk, liquid detergent, shampoo, rinse and the like.

  Moreover, as a liquid for improving the slidability with respect to the above viscous contents, edible oil or liquid paraffin (Hereafter, these are called an oily liquid.) Is suitable. These oily liquids are non-volatile liquids having a small vapor pressure at atmospheric pressure, and have a moderately high viscosity, so they are not only difficult to flow off from the inner surface of the bottle 10 but are olefin resins that form the inner surface of the bottle 10 Have a low interfacial tension with the like, spread on the inner surface of the bottle 10 to form a uniform film, and exhibit high liquid repellency to many viscous contents including water, and have a viscous content It is because it exhibits high slipperiness to objects.

Among the above-mentioned oily liquids, as edible oils, soybean oil, rapeseed oil, olive oil, rice oil, corn oil, vegetable oil, sesame oil, sesame oil, palm oil, castor oil, avocado oil, coconut oil, almond oil, walnut oil, An oil of palm oil, a salad oil, etc. can be illustrated, and it is also possible to use these in mixture. Also, depending on the kind of edible oil, it may be mixed with the contents and it may not form a film, but in such a case, it is mixed with the contents from other edible oils or liquid paraffin. You may select and use those that do not.
In addition, the above-mentioned oily liquid may be used as a mixture of two or more kinds to form an oil film, or as long as it does not affect the characteristics such as slipperiness exhibited by the liquid film, such as an interfacial slip agent Additives can also be blended appropriately.

  In the present invention, it is possible to form on the inner surface a surface structure with a high amount of retention for the liquid as described above.

  The invention is illustrated by the following experimental example.

1. Surface Shape Measurement A 50 mm × 50 mm test piece was cut out of a film produced by the method described later. The surface shape of the resin structure was measured using a non-contact surface shape measuring machine (NewView 7300, manufactured by zygo). MetroPro (Ver. 9.1.4 64-bit) was used as an application for measurement and image analysis. A range of 282.75 μm x 212.06 μm was measured. From the measurement data, the PV value in the measurement range and the number of protrusions were determined. Here, the PV value indicates the maximum height within the measurement range. Furthermore, when calculating the number of projections, the value of the ten-point average roughness of Example 5 described later was used as the value of Reference Band, and the projections derived from the roughening particles were counted as the number of projections.

Experimental Example 1
Using a Labo Plastomill, low density polyethylene (LDPE) as resin in extruder A, fine silica particles (average particle size: 5 μm) as roughening particles, LDPE / silica fine particles = 99/1 (weight Resin composition is supplied to the extruder B and extruded from a ring die head at a temperature of 210 ° C., and the inner side is LDPE, and the outer side is a grain-blended resin for roughening (LDPE / grains for roughening) A cylindrical two-layer film made of a resin composition was produced. When the film thickness of the film was measured by a microscope, the inner LDPE layer was about 60 μm, the outer fine particle-blended resin layer was about 70 μm, and the total was about 130 μm. Surface shape measurement was performed using the produced film. The results are shown in Table 1.

<Experimental Example 2>
A film was produced in the same manner as in Experimental Example 1 except that the weight ratio of the LDPE to the granular material for roughening was set to 90/10, and the surface shape was measured. The results are shown in Table 1.

<Experimental Example 3>
A film was produced in the same manner as in Experimental Example 1 except that crosslinked PMMA fine particles (average particle diameter: 10 μm) were used as the roughening particles, and the surface shape was measured. The results are shown in Table 1.

<Experimental Example 4>
A film was produced in the same manner as in Experimental Example 3 except that the weight ratio of the LDPE / roughening particle was changed to 90/10, and the surface shape was measured. The results are shown in Table 1.

Experimental Example 5
A film was produced in the same manner as in Experimental Example 1 except that both of the extruders A and B supplied LDPE, and the surface shape was measured. The results are shown in Table 1.

In the case of using a grain having a large grain size for roughening, the maximum height PV on the surface to be formed is larger than the PV in the case of using a grain having a small grain size for roughening, and large unevenness is formed. It is understood that it is done. However, looking at the number of protrusions on the surface to be formed, using a grain having a small grain size for roughening exhibits a larger value than a grain having a large grain size for graining, which is fine. It can be seen that a large number of asperities are formed.
From the above, the surface shape given by the difference in particle diameter is different, and in order to create a rough surface having large unevenness, it is effective to use a grain having a large particle diameter for roughening, while on the other hand In order to form a fine rough surface, it can be said that it is effective to use a grain having a small particle size for surface roughening.

1: Parison wall 3: Particle for roughing 10: Direct blow bottle 11: Neck 13: Shoulder 15: Torso 17: Bottom

Claims (3)

In a direct blow container in which an inner resin layer is formed by extrusion using a thermoplastic resin composition in which grains for roughening are dispersed in an amount of 1 to 20 parts by mass per 100 parts by mass of a thermoplastic resin ,
The graining material for roughening has a bidisperse particle size distribution having at least two maximal peaks , and the bidisperse particle size distribution has a first maximal peak in the range of 0.2 to 6 μm and 8 to 8 It has a second maximum peak in the range of 100 μm, and the first maximum peak and the second maximum peak have an interval of 3 μm or more, and the peak intensity of the first maximum peak X And the ratio of the peak intensity of the second maximum peak Y (X / Y) is in the range of 0.1 to 10, and
The surface of the inner surface resin layer is formed by particles having a small particle diameter in the roughened particles overlapping with large irregularities formed by particles having a large particle diameter in the roughened particles. It has a fractal structured surface with small irregularities formed,
A direct blow container , characterized in that a liquid film of edible oil or liquid paraffin is coated on the fractal structure surface to improve slipperiness of the contents contained in the container . The direct blow container according to claim 1 , wherein the roughening particles are at least one selected from the group consisting of metal oxides, metal salts, and organic fine particles. The direct blow container according to claim 1 , wherein the thermoplastic resin used to form the inner resin layer is an olefin resin.