JP5516091B2 - Olefin resin bottle for oily contents - Google Patents

Description

  The present invention relates to an olefin resin bottle used for containing viscous oily contents typified by mayonnaise.

  Plastic containers are widely used in various applications because they are easy to mold and can be manufactured at low cost. In particular, an olefin resin bottle whose inner wall is formed of an olefin resin such as low density polyethylene and formed by direct blow molding is a viscous slurry such as mayonnaise or ketchup from the viewpoint that the contents can be easily squeezed out. It is preferably used as a bottle for containing the contents in the form of paste or paste.

  For bottles containing viscous contents, the bottles may be stored in an inverted state so that the contents can be discharged quickly or used up to the end without remaining in the bottle. There are many. Therefore, when the bottle is turned upside down, there is a demand for the characteristic that the viscous contents do not remain attached to the inner wall surface of the bottle and fall quickly.

As a bottle satisfying such a requirement, for example, Patent Document 1 proposes a bottle having a multilayer structure in which an innermost layer is made of polyolefin having an MFR (melt flow rate) of 10 g / 10 min or more.
This multi-layered bottle is used to contain oily contents containing oils and fats such as mayonnaise, and the innermost layer has excellent wettability to oily contents. When inverted or inclined, oily contents such as mayonnaise fall along the innermost layer surface and fall cleanly without leaving the bottle inner wall surface (the innermost layer surface). It can be done.

  In addition, for bottles for viscous non-oil contents in which plant fibers such as ketchup are dispersed in water, Patent Document 2 or Patent Document 3 describes a saturated or unsaturated aliphatic as an organic lubricant in the innermost layer. A polyolefin resin bottle containing an amide has been proposed.

JP 2007-284066 A JP 2008-222291 A JP 2009-214914 A

  The polyolefin-based resin bottle disclosed in the above-mentioned patent document is an improved resin sliding property when the bottle is held in an inverted state from the surface of the resin layer material forming the inner surface of the bottle wall. Yes, in any bottle, the viscous content slides down at the bottle barrel wall at a fast sliding speed. Without adhering, the contents can be dropped downward (bottle mouth side), and the contents can be discharged cleanly and promptly.

  However, in the conventionally known polyolefin resin bottles used for viscous contents, the contents adhere to the bottom of the bottle, and it is difficult to effectively discharge the contents attached to the bottom. For this reason, there is a problem such as a large amount of contents remaining in the used bottle without being discharged, waste of resources, and troublesome washing of the bottle at the time of disposal. Is required.

  In addition, in order to improve the sliding property of the contents, the applicant of the present invention, in the olefin resin bottle for oily contents typified by mayonnaise, the innermost olefin resin layer is a lubricant-free layer. It is good to do (Japanese Patent Application No. 2009-38197), and in the olefin resin bottle for non-oil content represented by ketchup, the innermost olefin resin layer contains a saturated aliphatic amide as an organic lubricant. Even in such a case, the problem remains that the contents remain attached to the bottom of the bottle, making it difficult to discharge. .

  An object of the present invention is to provide a direct blow-molded olefin-based resin bottle having improved sliding properties on the inner surface of the bottom with respect to viscous oily contents such as mayonnaise.

According to the present invention, at least the inner surface is formed of an olefin resin, and the olefin resin bottle for oily contents formed by direct blow molding,
The lower end of the body wall of the bottle is a circumferential ground surface including a grounding portion when the bottle is held upright,
The bottom wall surrounded by the circumferential ground plane has at least one raised bottom portion higher than the circumferential ground plane,
The inner surface of the inclined wall descended from the raised bottom includes a sliding region where the inclination angle of the inclined wall tangent to the horizontal plane in a vertical cross section perpendicular to the inclined wall and perpendicular to the horizontal plane is 37 degrees or more,
When the bottom wall is projected onto a horizontal plane including the circumferential ground surface, the projected surface of the sliding region occupies 30% or more of the projected area. Provided.

In the olefin resin bottle for oily contents of the present invention,
(1) The raised bottom portion is formed at a position including a parting line that appears on the bottom wall derived from at least a split mold used for direct blow molding,
(2) The projected surface of the sliding area occupies 60% or more of the projected area of the bottom wall;
(3) Two or more raised bottom portions are formed,
(4) The bottle wall has a multilayer structure including the innermost layer of the olefin resin,
(5) The innermost layer is an organic lubricant-free layer,
Is preferred.

  In an olefin-based resin bottle by direct blow molding, a parison molded into a pipe shape by extrusion molding is sandwiched between split molds having cavities corresponding to the bottle shape, and one end of the parison is closed by this split mold (this In this state, air is supplied to the inside of the parison, and the parison is formed into a bottle shape by the blow pressure. For this reason, the bottom wall of the bottle has a substantially flat bottom in consideration of die cutting after molding, and a flat surface occupies most of the inner surface.

  However, in the olefin resin bottle for oily contents of the present invention, the bottom wall surrounded by the circumferential ground surface formed at the lower end of the body wall is lowered from the raised bottom portion formed higher than the circumferential ground surface. Forming a sliding region in which the inclination angle of the inclined wall tangent to the horizontal plane in a vertical cross section perpendicular to the inclined wall and perpendicular to the horizontal plane is 37 degrees or more, It has a novel characteristic in the point formed by the ratio.

  That is, the olefin-based resin bottle of the present invention has a raised bottom formed on the bottom wall surrounded by the ground contact surface, and although it is obtained by direct blow molding, it has an inclination gradient as described above. A large inclined wall (sliding area) occupies most of the bottom wall. Specifically, when the bottom wall is projected onto a horizontal plane including the ground contact surface, the projected surface of the sliding region occupies 30% or more, particularly 60% or more, and most preferably 75% or more of the projected area. . As a result, for oily contents such as mayonnaise, the sliding property on the inner surface of the bottom wall is improved, and the contents in the bottle can be discharged without waste. Therefore, the contents remaining in the used bottles are extremely small and can be easily cleaned when discarded.

The figure for demonstrating the principle of this invention. The figure which shows the olefin resin bottle for oil-based contents of this invention with a cap. It is a figure which shows the bottom wall of the bottle of FIG. 2, (a) is a projection figure of the bottom wall to the horizontal surface containing a ground surface, (b) is AA sectional drawing, (c) is BB sectional drawing. FIG. It is a figure which shows the bottom wall in the other example of the bottle of this invention, (a) is a projection figure of the bottom wall to the horizontal surface containing a ground plane, (b) is AA sectional drawing, (c). Is a BB cross-sectional view. The figure which shows the shaping | molding process of the olefin resin bottle for oily contents of this invention.

<Principle of the present invention>
In the olefin-based resin bottle for oil-based contents of the present invention formed by direct blow molding, the inclined wall (sliding region) whose inner surface is an inclined surface having an inclination angle of 37 degrees or more with respect to the horizontal plane occupies a certain proportion or more of the bottom portion. Thus, the contents adhering to the inner surface of the bottom can be quickly slid down to prevent the contents from adhering to the inner surface of the bottom. This principle will be described with reference to FIG. To do.

In FIG. 1, when the droplet 3 is attached to a predetermined surface 1, if the surface 1 is gradually inclined and the droplet 3 starts to slide when the tilt angle θ, the energy at this time is the attachment energy. And the following formula:
E = mg · sin θ / 2πr
Where E is the adhesion energy,
m is the mass of the droplet 3,
g is the acceleration of gravity,
r is the radius of the droplet 3,
θ is the sliding start angle (sliding angle),
It is represented by
As can be understood from this equation, as the inclination angle of the surface 1 becomes larger than the sliding angle θ, the droplet 3 can be quickly slid from the surface 1.

By the way, the above-mentioned adhesion energy varies depending on the type of the droplet 3 and the material of the surface 1, but the relationship between the sliding angle θ and the weight of the mayonnaise droplet is as follows. (The result of the Example mentioned later is summarized roughly.)
Mayonnaise droplet weight (mg) Sliding angle θ (degrees)
7 37
20 37
40 36
80 37

As understood from the above experimental results, the sliding angle θ does not depend on the mass of the droplet 3 and is substantially constant.
That is, according to the present invention, by forming a surface with a larger inclination angle than the sliding angle, specifically, a surface of 37 degrees or more at the bottom, the adhered content can be quickly slid regardless of the type and weight of the content. Accordingly, it is possible to effectively prevent the content remaining on the inner surface of the bottom portion.

<Bottle form>
As shown in FIG. 2, the olefin resin bottle for oily contents according to the present invention is indicated by 10 as a whole, and is connected to the neck portion 11 through a neck portion 11 having a thread and a shoulder portion 13. It has the bottom wall 17 which closes the lower end of the trunk | drum 15 and the trunk | drum wall 15, and after filling such a bottle 10 with an oily viscous content, it is aluminum in the upper end opening part of the neck part 11. A metal foil 19 such as a foil is applied by heat sealing, and a predetermined cap 20 is attached, thereby being used as a packaging bottle. In such a packaging bottle, the oil content is taken out by opening the cap 20, peeling off the metal foil 19 coated with the sealing material, and tilting or inverting the bottle 10.

Referring to FIG. 3, in this bottle 10, the circumferential lower end surface of the body wall 15 is a circumferential ground surface 30, and the region surrounded by the circumferential ground surface 30 is the bottom wall 17. It has become.
The circumferential ground surface 30 is a surface including a portion to be grounded when the bottle 10 is established and held, and the entire surface does not need to be grounded, and at least at three or more portions in the surface 30. It only has to be grounded.

  In the bottle 10 of the present invention, a raised bottom 31 is formed on the bottom wall 17 at a position higher than the circumferential ground surface 30, and an inclined wall 33 descending from the periphery of the raised bottom 31 is formed. Yes.

  By the way, since this bottle is formed by direct blow molding, the vertical wall X and the horizontal parting line derived from the split mold used for the molding appear on the bottom wall 17, and the above-mentioned increase The bottom 31 is formed so as to include the vertical parting line X (see FIG. 3A). In other words, the parting line X passes through the raised bottom portion 31. Normally, the raised bottom portion 31 is divided into two by the parting line X.

In the conventionally known direct blow-molded olefin resin bottle, even if the raised bottom portion 31 is formed on the bottom wall 17, the inclination angle is extremely small from the viewpoint of die cutting at the time of molding. It has a shape close to a flat bottom.
On the other hand, in the bottle 10 of the present invention, the sliding area where the inclination angle is 37 degrees or more occupies a certain ratio or more of the bottom wall.

That is, on the inner surface of the inclined wall 33 lowered from the raised bottom portion 31, there is an inclination angle with respect to the horizontal plane of the inclined wall tangent in a vertical cross section perpendicular to the inclined wall 33 and perpendicular to the horizontal plane. For example, this inclination angle is represented by α in the AA cross section (see FIG. 3B), and is represented by β in the BB cross section (see FIG. 3C). Each tilt angle exists.
That is, depending on the shape of the raised bottom 31, the inclination angle with respect to the horizontal plane in the vertical section differs depending on the position of the inclined wall 33, but in the bottle 10 of the present invention, this inclination angle is 37 degrees or more. An area (sliding area) is formed, and in such a sliding area, the inclination angle of the inner surface is equal to or greater than the sliding angle with respect to the oil-based content, so that the content remains attached to the inner surface of the bottom wall 17. It is possible to suppress it.

  The greater the inclination angle in the sliding region, the better the sliding property. On the other hand, if the tilt angle is increased more than necessary, the distance between the raised bottom 31 and the circumferential ground surface 30 becomes too large, and the contents of the bottle 10 are increased. The product will decrease. Therefore, the inclination angle in such a sliding region should be set to an appropriate range, and usually a range of 37 to 70 degrees is preferable.

  Further, in the present invention, the sliding region of the inclined wall 33 as described above is shown in the projection view on the horizontal plane including the ground contact surface 30 in FIG. It is also important that the bottom wall 17 occupies 30% or more, preferably 60% or more, and more preferably 75% or more of the projected area of the bottom wall 17). In other words, in the present invention, since the ratio of the inclined wall 33 in the sliding region occupying the bottom wall 17 is large, the sliding wall 33 can sufficiently exhibit the effect of improving the sliding property against the oily content, and the contents on the inner surface of the bottom wall 17 can be achieved. Thus, it is possible to effectively prevent the adhesion and adhesion of objects. For example, even if the sliding region as described above is formed on the inclined wall 33, if the area ratio is small, the sliding property improvement effect by the sliding region is small, and the oil-based content on the inner surface of the bottom wall 17 is small. It becomes difficult to effectively prevent the remaining adhesion.

  In the aspect of the present invention described above, in the embodiment shown in FIG. 3, the planar shape of the raised bottom portion 31 is a rectangle or an elliptical shape close to a rectangle. However, this planar shape may be a circle, or as described above. As long as the area ratio of the inclined wall 33 is within a predetermined range, two or more raised bottom portions 31 may be formed.

For example, as shown in FIG. 4, in this example, two raised bottom portions 31 a and 31 b are formed on the bottom wall 17, and accordingly, in the central portion between the two raised bottom portions 31. A downward convex portion 35 having a lower end surface is formed near the same surface as the ground contact surface 30. Even in such a case, by satisfying the above-described conditions for the area ratio of the sliding region where the inclination angle of the inner surface of the inclined wall 33 descending from the raised bottom portions 31a and 31b is 37 degrees or more, It is possible to improve the sliding property of the oil-based contents with respect to the inner surface of the bottom wall 17 and to effectively suppress the remaining adhesion.
In particular, when a plurality of raised bottom portions 31 are provided in this way, a downward convex portion 35 is formed accordingly, so that the internal volume of the bottle 10 can be reduced even when the inclination angle in the sliding region is set large. There is an advantage that it can be suppressed.

  In FIG. 4, the raised bottom portions 31a and 31b are provided parallel to the major axis of the circumferential ground surface 30, but may be provided parallel to the minor axis, or may be provided in a direction other than the major axis direction or the minor axis direction. Also good.

<Bottle molding>
The olefin resin bottle for oil-based contents of the present invention having the above-described bottom wall shape is molded by direct blow molding in the molding process shown in FIG.

  First, in order to directly blow mold the olefin resin bottle of the present invention, a four-part mold is used as shown in FIG. The four-part mold includes an upper mold 40 for molding the trunk, shoulder and neck, and a lower mold 41 for molding the bottom wall from below the trunk. Are divided into two. That is, the olefin resin bottle of the present invention has a raised bottom portion that is connected to an inclined wall including a sliding region having a large inclination angle on the bottom wall, so that in a two-part mold used in normal direct blow molding, Since it becomes difficult to perform die cutting, it is necessary to use such a four-part mold.

  At the time of molding, as shown in FIG. 5A, a mold is formed by integrating a pair of one upper mold 40a and a lower mold 41a and a pair of the other upper mold 40b and the lower mold 41b. A pipe-shaped parison 50 formed by melt extrusion using an olefin resin and maintained at a predetermined molding temperature (150 to 230 ° C.) is introduced between the pair of molds.

  Next, as shown in FIG. 5 (b), the above-described pair of molds is closed. In particular, the lower part of the parison 50 is closed by closing the lower molds 41a and 41b. In this state, by blowing air from the opening at the top of the parison 50, the parison 50 is shaped into a bottle according to the cavity formed on the inner surface of the mold.

After the shaping into the bottle shape, as shown in FIG. 5 (c), the lower molds 41a and 41b remain in a paired state and are lowered separately from the upper molds 40a and 40b, and shaped. Open the bottom wall of the bottle.
Next, as shown in FIG. 5 (d), the pair of upper molds 40a and 40b is opened, the pair of lower molds 41a and 41b is opened at the same time, and the molded bottle 10 is taken out to complete direct blow molding. To do.

  Thus, the olefin resin bottle for oily contents of the present invention having the bottom wall in which the steep inclined wall occupies a large proportion by performing molding using the four-part mold as described above. It can be manufactured.

  Further, the bottle of the present invention is not limited to the production by a four-part mold, and can be produced by, for example, a three-part mold. In the three-part mold, the lower molds 41a and 41b are integrated to form a bottom mold. When the upper molds 40a and 40b are closed, the lower part of the parison 50 at the upper part of the mold is fused. The parison 50 with the bottom fused is moved into a mold and blown to form a bottle. After the bottle molding, the bottom mold moves downward, the upper molds 40a and 40b are opened, and the bottle is taken out.

<Layer structure and layer forming material of bottle wall>
In the olefin-based resin bottle of the present invention, the bottle wall may be formed of a single layer of olefin-based resin, but usually the innermost layer (layer in contact with the contents) and the outermost layer (layer exposed on the outer surface). ) Is formed of an olefin-based resin, and an intermediate layer having an appropriate function is preferably provided between the innermost layer and the outermost layer. It is preferable to blend a lubricant.

1. Lubricant;
For example, the outermost layer is required to impart slidability to the outer surface of the bottle and to prevent the bottles from sticking to each other during bottle conveyance, thereby enhancing the conveyance of the bottle. For this reason, it is preferable to use a lubricant and to have a layer structure in which the lubricant bleeds on the outer surface of the bottle. As such a lubricant, various known ones can be used, for example,
(B) Hydrocarbons such as fluid, natural or synthetic paraffin, micro wax, polyethylene wax, chlorinated polyethylene wax,
(B) Fatty acids such as stearic acid and lauric acid,
(C) Aliphatic amides such as stearic acid amide, palmitic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, methylene bisstearamide, ethylene bisstearamide,
(D) Fatty acid esters such as butyl stearate, hydrogenated castor oil, ethylene glycol monostearate,
(E) alcohols such as cetyl alcohol and stearyl alcohol;
(F) Metal soap such as zinc stearate, calcium stearate,
(G) polyorganosiloxane,
Organic lubricants such as these can be mentioned, and these can be used alone or in combination of two or more.
In the present invention, aliphatic amides are particularly preferable in terms of good bleeding properties. Among them, unsaturated aliphatic amides such as oleic acid amide and erucic acid amide have a low melting point and are most easily bleeded. Best suited for invention.

  In this case, the organic lubricant can be blended directly into the outermost layer, but the olefinic resin layer is used as an intermediate layer (outermost layer adjacent layer) so as to be adjacent to the outermost layer using the same olefinic resin as the outermost layer. It is particularly preferable that the organic lubricant is blended in such an adjacent layer. In other words, when an organic lubricant is blended directly into the outermost layer, the organic lubricant bleeds to the outermost layer surface during the molding of the bottle, and as a result, blisters and the like are generated on the outer surface of the bottle, and the appearance of the bottle is impaired. May end up. However, no lubricant is blended in the outermost layer, and the layer adjacent to this is a layer containing an organic lubricant (hereinafter, simply referred to as a lubricant-containing layer), so that the lubricant on the outermost layer surface at the time of bottle molding is used. Bleeding can be prevented, the occurrence of blisters can be effectively prevented, and the appearance of the bottle can be maintained well.

  In addition, said organic lubricant is normally mix | blended in the quantity of 0.01 to 0.5 weight%, especially 0.02 to 0.1 weight% in the outermost layer or the adjacent layer adjacent to the outermost layer.

In addition, oily contents such as mayonnaise have a sliding action with respect to the olefin resin on the innermost surface of the inner layer, but the organic lubricant is blended in the innermost layer and the organic lubricant bleeds on the innermost surface. If this happens, the slipperiness of the oil component will be impaired. For this reason, it is suitable not to mix | blend an organic lubricant in an innermost layer and to make an innermost layer into an organic lubricant-free layer.
In addition to the organic lubricants described above, inorganic lubricants such as silicon oxide, silicon carbide, lithium fluoride, and calcium carbonate are also known as lubricants. However, such inorganic lubricants are effective for sliding oily contents. It is possible to add an inorganic lubricant to the innermost layer because it has no effect.

2. Middle layer;
In the present invention, as understood from the above description, an appropriate lubricant is blended in an appropriate amount in the outermost layer (or the outermost adjacent layer), but provided between the outermost layer and the innermost layer. It is desirable that the intermediate layer to be provided has a lubricant blocking function. That is, if the organic lubricant blended in the outermost layer or the outermost layer adjacent layer bleeds to the surface of the innermost layer, there is a possibility that the slipping property with respect to the oily content may be impaired.

The intermediate layer functioning as a lubricant blocking layer is usually formed of a resin having a density of 1.00 g / cm ³ or more and a glass transition point (Tg) of 35 ° C. or more, that is, an intermediate layer formed of such a resin. The layer becomes a dense layer, whereby the intermediate layer effectively functions as a lubricant blocking layer, and the migration of the organic lubricant blended in the outer layer from the intermediate layer is effectively suppressed, It is possible to stably keep the sliding property against the contents. For example, when the intermediate layer is formed using a resin having a density or glass transition point (Tg) lower than the above range, the intermediate layer becomes a loose layer, and the function as a lubricant blocking layer is not exhibited. As a result, there is a risk that the sliding property with respect to the oil-based content is lowered by bleeding of the organic lubricant onto the innermost layer surface.

  The resin for forming the intermediate layer is not particularly limited as long as both the density and the glass transition point (Tg) are within the above ranges, and any thermoplastic resin that can be molded can be used. In general, it is preferable to use a gas barrier resin such as an ethylene vinyl alcohol copolymer (saponified ethylene vinyl acetate copolymer) or an aromatic polyamide, and it is most preferable to use an ethylene vinyl alcohol copolymer. is there. That is, by using a gas barrier resin as the resin for forming the intermediate layer, the intermediate layer can be provided with an oxygen barrier property as well as a lubricant blocking property. In particular, an ethylene vinyl alcohol copolymer has a particularly excellent oxygen barrier property. For this reason, it is possible to effectively suppress the oxidative deterioration of the contents due to oxygen permeation, and it is possible to maintain excellent sliding properties and at the same time to ensure excellent contents preservation.

  The ethylene vinyl alcohol copolymer as described above is generally an ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%, and a saponification degree of 96 mol% or more, In particular, a saponified copolymer obtained by saponification so as to be 99 mol% or more is preferable, and those having a density and a glass transition point (Tg) in the above-mentioned range are selectively used. The

  The thickness of the intermediate layer functioning as the lubricant blocking layer is generally in the range of 1 to 50 μm, preferably 9 to 40 μm. If this thickness is excessively thin, the lubricant blocking property is lowered, and it may be difficult to effectively prevent the organic lubricant from moving to the innermost surface layer side. This is because a further improvement in the lubricant blocking property cannot be obtained, and on the contrary, the thickness of the bottle becomes thicker than necessary, or inconvenience occurs in terms of an increase in cost.

  Further, when the gas barrier resin as described above is used as an intermediate layer, it is preferable to provide the intermediate layer via an adhesive resin layer in order to enhance adhesion with the inner and outer layers and prevent delamination. Thereby, the intermediate layer can be firmly fixed to the inner and outer layers. Adhesive resins used for forming such an adhesive resin layer are known per se. For example, a carbonyl group (> C═O) is 1 to 100 meq / 100 g resin in the main chain or side chain, particularly 10 to 100 meq / 100 g. Resin contained in the amount of resin, specifically, olefin resin graft-modified with carboxylic acid such as maleic acid, itaconic acid, fumaric acid or its anhydride, amide, ester, etc .; ethylene-acrylic acid copolymer; An ion-crosslinked olefin copolymer; an ethylene-vinyl acetate copolymer; and the like are used as the adhesive resin. The thickness of such an adhesive resin layer may be such that an appropriate adhesive force can be obtained, and is generally 0.5 to 20 μm, preferably about 1 to 8 μm. Such an intermediate layer can also function as a lubricant blocking layer as long as the above-described density and glass transition point conditions are satisfied.

3. Outermost layer and innermost layer;
Further, the polyolefin resin forming the outermost layer located on the outermost surface of the bottle and the innermost layer located on the innermost surface is not particularly limited. For example, 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, it may be a random or block copolymer of α-olefins such as ethylene, propylene, 1-butene and 4-methyl-1-pentene. Further, the outermost layer and the innermost layer can also be formed from the cyclic olefin copolymer disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2007-284066) described above. In the present invention, particularly preferably used olefin-based resins are polyethylene and polypropylene, and polyethylene is most suitable. In particular, in order to impart squeeze properties to the bottle and take out the contents of the bottle by squeezing, it is low. It is preferable to form the outermost layer and the innermost layer using density polyethylene or linear low density polyethylene.

Moreover, in the bottle of the present invention in which oily contents such as mayonnaise are accommodated, as described above, it is preferable that the innermost layer is an organic lubricant-free layer, but such an organic lubricant-free layer is used. As the olefin resin for forming the innermost layer, among the olefin resins as described above, those having an MFR (190 ° C.) of 10 g / 10 min or more and / or a density of 0.91 g / cm ³ or less are suitable. It is. That is, such an olefin resin has low crystallinity, exhibits high wettability with oily substances such as mayonnaise, and exhibits excellent sliding properties with respect to oily contents contained in bottles. In particular, linear low density polyethylene (hereinafter sometimes referred to as ultra-low density linear polyethylene) having a density of 0.91 g / cm ³ or less has particularly high wettability with respect to oily contents, and exhibits excellent sliding properties. This is the most suitable.
Such linear low density polyethylene is particularly low density among conventionally known low density polyethylenes. For example, using a metallocene catalyst, ethylene and a small amount of α-olefin (with a carbon number of 8 or less). It is a very special low density polyethylene obtained by copolymerization of a certain α-olefin other than ethylene.

Further, the innermost layer, which is an organic lubricant-free layer, preferably has an average surface roughness Ra (JIS B 0106-1994) of 0.3 μm or less in order to obtain high wettability with respect to oily contents. is there. In particular, in the above-mentioned linear low density polyethylene, melt fracture is likely to occur, and rough skin called shark skin occurs on the parison surface. In particular, this phenomenon becomes significant when the density exceeds 0.91 g / cm ³ . For this reason, in order to achieve such a surface roughness Ra, it is preferable to set the density to 0.91 g / cm ³ or less. Further, as a molding method, it is preferable to open a clearance between the shell and the core at the parison exit portion by 1.0 mm or more. It is also effective to coat the shell and the core to improve the slipperiness such as fluorine. Furthermore, it is also effective to make the surface of the mold used for molding a mirror surface. If the surface roughness Ra exceeds this range, the wettability with respect to the oil-based content may be deteriorated, and the sliding property of the content may be lowered.

Furthermore, in the present invention, as the olefin resin for forming the outermost layer, the MFR (190 ° C.) is 10 g / 10 min or more and / or the density is 0.91 g among the olefin resins described above, as in the innermost layer. A linear low density polyethylene having a density in the range of / cm ³ or less, particularly a density of 0.91 g / cm ³ or less, is particularly suitable. That is, when the outermost layer is formed of such an olefin-based resin, the outermost layer becomes a relatively loose layer. As a result, the bleeding property of the lubricant is improved, and the organic lubricant blended in the outer layer of the intermediate layer is obtained. This is because the surface of the outermost layer is quickly bleeded, and as a result, the transportability of the bottle is improved, and the bottles can be adhered to each other during transport and the bottle can be effectively prevented from adhering to a transport material such as a belt. .

  The thicknesses of the outermost layer and the innermost layer as described above are set to such an extent that the function of each layer is effectively exhibited and the thickness is not increased more than necessary. For example, in the outermost layer, the lubricant can effectively bleed on the surface, and excellent bottle transportability can be ensured, and the innermost layer can ensure excellent sliding property against the oily contents contained in the bottle. In addition, the thickness is appropriately set according to the layer structure of the bottle so that the entire thickness of the bottle does not become unnecessarily thick.

4). Outermost adjacent layer;
As already described, in the present invention, in order to impart slipperiness to the outer surface of the bottle, a predetermined amount is provided at a position adjacent to the outermost layer (for example, between the aforementioned lubricant-blocking intermediate layer and outermost layer). It is preferable to blend a lubricant. That is, as the resin forming the outermost layer adjacent layer, generally, the same type of olefin resin as that of the outermost layer is used in order to prevent delamination. When such an adjacent layer is formed using a resin having poor adhesion to the outermost layer, it is necessary to interpose an adhesive resin layer, which is disadvantageous in terms of cost and the like. is there.

  For forming the outermost layer adjacent layer as described above, regrind (scrap resin) generated at the time of bottle molding can be used by mixing with virgin olefin resin. In this case, from the viewpoint of reusing resources while maintaining moldability, the amount of regrind is preferably about 10 to 60 parts by weight per 100 parts by weight of virgin olefin resin.

  If the thickness of the outermost layer adjacent layer as described above is such that the total thickness of the bottle wall does not become more than necessary, and the lubricant blended in this layer can quickly bleed into the outermost layer. In general, the thickness is generally set to about 20 to 200 μm.

  Each layer described above may be appropriately blended with various compounding agents, for example, pigments, ultraviolet absorbers and the like, in such an amount that does not impair the properties required for each layer.

It is as follows when the description mentioned above is put together and the suitable example of the layer structure of the bottle wall of the olefin resin bottle of this invention in which an oil-based content is accommodated is shown. (In the following examples, AD represents an adhesive layer.)
Outermost layer (containing lubricant) / AD / lubricant blocking intermediate layer / AD / innermost layer (free of organic lubricant)
Outermost layer (organic lubricant free) / adjacent layer (containing machine lubricant) / AD / lubricant blocking intermediate layer / AD / innermost layer (organic lubricant free)

  The olefin-based resin bottle of the present invention having the layer structure as described above is obtained by melt-extruding the above-described tubular parison by co-extrusion using a resin composition for forming each layer, and according to the process of FIG. Manufactured by direct blow molding.

The direct blow molded olefin resin bottle of the present invention produced as described above is filled with oily contents such as mayonnaise, various dressings and liquid detergents, and has a viscosity of 100 cps or more, particularly at 25 ° C. It is applied to a thick paste or slurry-like oily content.
Such a bottle of the present invention can be easily discharged by dropping the viscous content to the mouth side by storing it upside down, and it can be easily discharged to the bottom wall of the bottle. It is possible to effectively suppress the remaining adhesion of the contents and greatly reduce the amount of oily contents remaining in the used bottle.

The invention is illustrated in the following examples.
In addition, the various characteristics, the measuring method of physical properties, etc. which were performed in the following Examples etc. and the resin etc. which were used for the shaping | molding of a bottle are as follows.

(1) Sliding angle The sliding angle of the bottles of Examples and Comparative Examples was evaluated by the following measurement.
After the obtained bottle was stored at room temperature for 7 days, a flat test piece of 30 mm × 30 mm was cut out from the side wall of the container, and this test piece was mounted with the slide-down method kit DM-SA so that the inner layer was on top. Fixed on a sample stage of a solid-liquid interface analysis system DropMaster700 (manufactured by Kyowa Interface Science Co., Ltd.), using mayonnaise as a liquid sample, dripping a predetermined weight on the inner layer surface, conditions of room temperature 23 ° C. and humidity 50% RH Then, the specimen angle was tilted from zero degree to 90 degrees at a speed of 2 degrees per second. The angle at which the droplet started to slide down the specimen was measured. Droplet weight was tested at any of 7-50 mg.

  Each measurement was performed three times, and the average value was used as a representative value for each test. The average value of the representative values obtained with a droplet weight of 7 to 50 mg was taken as the sliding angle. In the experiment, mayonnaise was manufactured by Kewpie Co., Ltd., and had a lipid content of about 75%.

(2) Area ratio of inclined wall of bottle bottom wall From the bottom view of the bottle bottom wall, the area ratio (%) of the surface above the sliding angle was determined and shown in Table 1. In the bottom view, the entire area inside the ground contact surface of the bottle bottom wall is 100% (bottom wall area), and the inclination angle of the inclined wall tangent to the horizontal plane in the vertical section perpendicular to the inclined wall and perpendicular to the horizontal plane is 37 degrees or more. The surface area was divided and the ratio of the bottom wall area to the sliding wall area ratio was expressed in%.

(3) Measurement of physical properties of the resin used The MFR of the resin used for forming each layer was measured by ASTM D123 (190 ° C), the density was measured by ASTM D792, and the glass transition point (Tg) was 0 ° C or higher. The DSC method was used, and when the temperature was less than 0 ° C., the dynamic viscoelasticity method was used.

(4) Evaluation of remaining amount of contents The formed bottle was filled with mayonnaise at room temperature, sealed with a plastic cap, stored at room temperature for 1 day, and then removed from the opening. Air was poured into the bottle from which the contents had been discharged, and the bottle was allowed to stand at 5 ° C. for 24 hours in an inverted state (the opening was down). Then, it cut | disconnected to the bottom wall side and the opening part side (mouth part side) in the center part of the bottle, and measured the weight of the bottom wall side bottle.
Next, the bottle on the bottom wall side was washed to remove the adhered contents, and then the weight was measured again, and the difference was defined as the adhered contents remaining amount (g).
Table 1 shows the average of the remaining contents determined for n = 5 (n is the number of tests).
The remaining content (g) obtained was scored according to the following criteria. ○ and △ were acceptable levels.
○: Less than 9.0 (g) Δ: 9.0 (g) or more and less than 12.0 (g) ×: 12.0 (g) or more

(5) Resin type and lubricant used The following resins were used for forming each layer of the bottle.
<Outermost layer, adhesive layer, lubricant blocking layer>
Outermost layer forming resin:
Low density polyethylene
MFR; 1.1g / 10min
Density: 0.92 g / cm ³
(As a lubricant, containing 0.03% by weight of oleic acid amide)
Adhesive layer: Maleic anhydride-modified polyethylene Lubricant blocking layer (intermediate layer):
Ethylene vinyl alcohol copolymer (density 1.19 g / cm ³ , Tg 69 ° C.)
<Resin for innermost layer>
Resin A:
Linear low density polyethylene
MFR; 2.0g / 10min
Density: 0.90 g / cm ³
(Without lubricant)
Resin B:
Cyclic polyolefin
Density: 1.02 g / cm ³
Tg: 80 ° C
(Without lubricant)

Example 1
Low density polyethylene containing 0.03% by weight of oleic acid amide (lubricant) as the outermost layer forming resin in a 50 mm extruder, maleic anhydride-modified polyethylene as the adhesive layer forming resin, 40 mm In the sub-extruder B, an ethylene vinyl alcohol copolymer is used as a resin for forming a lubricant blocking intermediate layer, and in the 40 mm sub-extruder C, a resin A (a linear low-density polyethylene containing no lubricant) is used as an innermost layer-forming resin. 4 pieces of mayonnaise bottles having a nozzle diameter of 30 mm, an internal volume of 500 ml, and a weight of 19 g by direct blow molding using a four-part mold, extruding molten parison from a multilayer die head having a temperature of 210 ° C. A seed 5 layer multilayer container was prepared.

The body layer structure of this bottle is as follows.
Outermost layer: 200 μm
Adhesive layer: 5 μm
Lubricant blocking intermediate layer: 25 μm
Adhesive layer: 5 μm
Innermost layer: 115 μm
Further, the bottom wall shape of this bottle is as shown in FIG. 3, the planar shape of the raised bottom is elliptical, the inclination angle α in FIG. 3 is 60 degrees, the inclination angle β is 40 degrees, and the inclination angle is 37. The area ratio of the sliding surface above the degree is 85%.
Furthermore, the average surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
About this bottle, the sliding angle measurement and the content residual amount measurement were performed using mayonnaise, and the result was shown in Table 1 and Table 2 with the bottle bottom wall specification (bottom wall shape).
The sliding angle is shown in Table 2 as the value of the innermost layer resin A.

(Example 2)
A bottle was prepared in the same manner as in Example 1 except that the resin B (cyclic polyethylene not containing a lubricant) was used as the innermost layer forming resin.
The shape of the bottom wall of this bottle is the same as that of Example 1, and the area ratio of the sliding surface with an inclination angle of 37 degrees or more is 85%. Moreover, the surface average surface roughness Ra of the innermost layer of the bottle was 0.26 μm.
Tables 1 and 2 show the specifications of the bottle bottom wall, the sliding angle using mayonnaise, and the evaluation results for the remaining amount of contents. The sliding angle is shown in Table 2 as the value of the innermost layer resin B.

(Example 3)
In FIG. 3, the inclination angle α is 60 degrees and the inclination angle β is 40 degrees, which is the same as in the first embodiment, but the area of the sliding surface where the sliding angle is 37 degrees or more by increasing the width of the BB cross section of the raised bottom. The shape of the bottom wall was changed so that the ratio was 30%, and a bottle was produced in the same manner as in Example 1. The average inner surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
Table 1 shows the results of evaluation of the bottle bottom wall specifications and the remaining amount of content for mayonnaise.
The sliding angle is shown in Table 2 as the value of the innermost layer resin A because the same resin A as in Example 1 is used as the innermost layer resin.

Example 4
In FIG. 3, the inclination angle α is 60 degrees, the inclination angle β is 37 degrees, and the width of the BB cross section of the raised bottom is increased so that the area ratio of the sliding surface with a sliding angle of 37 degrees or more is 30%. A bottle was prepared in the same manner as in Example 1 by changing the shape of the bottom wall. The average inner surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
Table 1 shows the specifications of the bottom wall of the bottle, the sliding angle for the mayonnaise, and the evaluation results for the remaining amount of contents.
The sliding angle is shown in Table 2 as the value of the innermost layer resin A because the same resin A as in Example 1 is used as the innermost layer resin.

(Example 5)
In FIG. 3, the inclination angle α is 60 degrees and the inclination angle β is 40 degrees, which is the same as in the first embodiment, but the area of the sliding surface where the sliding angle is 37 degrees or more by increasing the width of the BB cross section of the raised bottom. The shape of the bottom wall was changed so that the ratio was 40%, and a bottle was produced in the same manner as in Example 1. The average inner surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
Table 1 shows the specifications of the bottom wall of the bottle, the sliding angle for the mayonnaise, and the evaluation results for the remaining amount of contents.
The sliding angle is shown in Table 2 as the value of the innermost layer resin A because the same resin A as in Example 1 is used as the innermost layer resin.

(Example 6)
In FIG. 3, the inclination angle α is 60 degrees and the inclination angle β is 40 degrees, which is the same as in the first embodiment, but the area of the sliding surface where the sliding angle is 37 degrees or more by increasing the width of the BB cross section of the raised bottom. The shape of the bottom wall was changed so that the ratio was 60%, and a bottle was produced in the same manner as in Example 1. The average inner surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
Table 1 shows the specifications of the bottom wall of the bottle, the sliding angle for the mayonnaise, and the evaluation results for the remaining amount of contents.
The sliding angle is shown in Table 2 as the value of the innermost layer resin A because the same resin A as in Example 1 is used as the innermost layer resin.

(Example 7)
As shown in FIG. 4, the bottom wall has a shape having two flat raised bottoms, the inclination angle α in FIG. 4 is 60 degrees, the inclination angle β is 40 degrees, and the sliding angle is 37 degrees or more. A bottle was produced in the same manner as in Example 1 except that the area ratio of the sliding surface was changed to 75%. The average inner surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
Table 1 shows the specifications of the bottom wall of the bottle, the sliding angle for the mayonnaise, and the evaluation results for the remaining amount of contents.
The sliding angle is shown in Table 2 as the value of the innermost layer resin A because the same resin A as in Example 1 is used as the innermost layer resin.

(Example 8)
3 except that the planar shape of the raised bottom is circular, the inclination angle α in FIG. 3 is 45 degrees, the inclination angle β is 60 degrees, and the area ratio of the sliding surface with a sliding angle of 37 degrees or more is 97%. Produced a bottle in the same manner as in Example 1. The average inner surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
Table 1 shows the specifications of the bottom wall of the bottle, the sliding angle for the mayonnaise, and the evaluation results for the remaining amount of contents.
The sliding angle is shown in Table 2 as the value of the innermost layer resin A because the same resin A as in Example 1 is used as the innermost layer resin.

(Comparative Example 1)
In FIG. 3, the inclination angle α is 10 degrees, the inclination angle β is 10 degrees, and the width of the BB cross section of the raised bottom is increased so that the area ratio of the sliding surface with a sliding angle of 37 degrees or more becomes 0%. A bottle was prepared in the same manner as in Example 1 except that the shape of the bottom wall was changed. The average inner surface roughness Ra of the innermost layer of this bottle was 0.26 μm.
Table 1 shows the specifications of the bottom wall of the bottle, the sliding angle for the mayonnaise, and the evaluation results for the remaining amount of contents.
The sliding angle is shown in Table 2 as the value of the innermost layer resin A because the same resin A as in Example 1 is used as the innermost layer resin.

17: Bottom wall 30: Circumferential ground surface 31: Raised bottom 33: Inclined wall

Claims (6)

In the olefin resin bottle for oily contents, at least the inner surface is formed of an olefin resin and molded by direct blow molding,
The lower end of the body wall of the bottle is a circumferential ground surface including a grounding portion when the bottle is held upright,
The bottom wall surrounded by the circumferential ground plane has at least one raised bottom portion higher than the circumferential ground plane,
The inner surface of the inclined wall descended from the raised bottom includes a sliding region where the inclination angle of the inclined wall tangent to the horizontal plane in a vertical cross section perpendicular to the inclined wall and perpendicular to the horizontal plane is 37 degrees or more,
The olefin-based resin bottle for oily contents, wherein when the bottom wall is projected onto a horizontal plane including the circumferential ground surface, the projected surface of the sliding region occupies 30% or more of the projected area.   The olefin resin bottle for oily contents according to claim 1, wherein the raised bottom portion is formed at a position including a parting line that appears on the bottom wall derived from at least a split mold used for direct blow molding.   The olefin resin bottle for oily contents according to claim 1 or 2, wherein the projected surface of the sliding region occupies 60% or more of the projected area of the bottom wall. The olefin resin bottle for oily contents according to any one of claims 1 to 3, wherein two or more raised bottom portions are formed. The olefin resin bottle for oily contents according to any one of claims 1 to 4 , wherein the bottle wall has a multilayer structure including the innermost layer of the olefin resin.   The olefin resin bottle according to claim 5, wherein the innermost layer is an organic lubricant-free layer.

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