JP6011058B2 - Plastic container - Google Patents

Description

  The present invention relates to a plastic container in which the contents have good sliding properties and the contents can be easily discharged.

  Plastic bottles are widely used for various applications from the viewpoint of easy molding and low cost production. For example, a plastic bottle formed of a polyolefin-based resin layer such as polyethylene is used as a container for containing a viscous slurry-like or paste-like substance.

  The above plastic bottles provide slipperiness to improve blocking resistance and prevent inconveniences such as sticking of bottles in the transport process on the production line or adhesion between the bottle and a transport material such as a transport belt. It is necessary to.

  For this reason, for example, Patent Document 1 (Japanese Patent No. 2627127) discloses that a base resin constituting a bottle includes a low melting point fatty acid amide such as an unsaturated aliphatic amide (for example, oleic acid amide) and a saturated fat. It has been proposed to blend a fatty acid amide having a high melting point such as a group amide (for example, stearic acid amide or behenic acid amide) as a lubricant.

  Patent Document 2 (Japanese Patent Laid-Open No. 2009-214914) proposes blending an unsaturated aliphatic amide and a saturated aliphatic amide as a lubricant in the innermost layer constituting the bottle.

Japanese Patent No. 2627127 JP 2009-214914 A

  By the way, the slipperiness between the lubricant blended in the innermost layer and the contents varies greatly depending on the components of the contents. For example, a thickener such as a thickening polysaccharide such as mayonnaise-like food is added. As for the contents, the containers such as bottles to which the above-mentioned lubricant is added tend to adhere to the inner wall surface, resulting in poor sliding properties.

  For this reason, development of a container that can slide down well even with a highly viscous content blended with a thickener is considered necessary.

  This invention is made | formed in view of the said situation, and it aims at providing the plastic container excellent in the sliding property suitable for the highly viscous content which mix | blended the thickener especially.

  In order to achieve this object, the present invention has the following features.

The plastic container according to the present invention is
At least three or more hydroxyl groups are added to the base resin constituting the layer in contact with the contents, and a room temperature solid polyhydric alcohol fatty acid ester that is not fully esterified is added ,
The base resin contains a liquid polyhydric alcohol fatty acid ester,
The blend ratio of the normal-temperature solid polyhydric alcohol fatty acid ester and the liquid polyhydric alcohol fatty acid ester is 4: 1 to 1: 4 .

  According to the present invention, it is possible to obtain a plastic container excellent in sliding property, which is suitable for a highly viscous content blended with a thickener.

It is a figure which shows the structural example of the plastic bottle 100 of this embodiment. It is a figure which shows the evaluation result of the slipperiness of a plastic bottle.

<Outline of plastic container according to the present invention>
First, the outline | summary of the plastic container concerning this invention is demonstrated.

  The plastic container according to the present invention is a plastic container having a multilayer structure or a single layer structure.

  The plastic container according to the present invention includes a base resin (base resin in contact with the contents) constituting at least the innermost layer of the multilayer structure or a base resin (base in contact with the contents) constituting the single layer of the single layer structure. In addition, a lubricant of polyhydric alcohol fatty acid ester is added to the material resin, and the slidability of the contents is improved by bleeding out. The polyhydric alcohol fatty acid ester to be added preferably has at least three hydroxyl groups and is not fully esterified. Liquid polyhydric alcohol fatty acid esters are solid at room temperature (23 ° C) because polyhydric alcohol fatty acid esters that bleed out along with slipping of the viscous material dissolve in the viscous material, making it difficult to improve the slipperiness. It is preferable that there is.

  By adding the lubricant of the polyhydric alcohol fatty acid ester satisfying the above conditions to the base resin constituting the layer in contact with the contents, the slipperiness with respect to the contents can be improved. As a result, it is possible to obtain a plastic container excellent in sliding properties suitable for a highly viscous content blended with a thickener. In addition, by adding the above-mentioned lubricant to the base resin (outermost layer) on the side opposite to the contents side, the slipperiness between containers at the time of container molding can be improved, and line suitability can be improved. Hereinafter, the plastic container according to the present invention will be described in detail. In the following description, a plastic bottle will be described as an example. However, the plastic container according to the present invention is not limited to the plastic bottle described below, and can be applied to various containers such as a package.

<Configuration example of plastic bottle 100>
First, a configuration example of the plastic bottle 100 of the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration example of a plastic bottle 100 according to the present embodiment.

  The plastic bottle 100 of the present embodiment has a multilayer structure of an outermost layer 1, an intermediate layer 2, and an innermost layer 3.

  The plastic bottle 100 of the present embodiment includes a lubricant specific to the present embodiment in the outermost layer 1 and the innermost layer 3, and is excellent in slipperiness for the contents and slippery between the bottles by the lubricant. It also makes it possible to obtain an excellent plastic bottle 100.

<Middle layer 2>
The intermediate layer 2 of the present embodiment is configured without blending a lubricant. As the resin constituting the intermediate layer 2 of this embodiment, any moldable thermoplastic resin can be used, and a resin having gas barrier properties is preferable.

  As the intermediate layer 2, for example, ethylene vinyl alcohol copolymer (saponified ethylene vinyl acetate copolymer) or aromatic polyamide can be used. In particular, ethylene vinyl alcohol copolymer has excellent oxygen barrier properties. Therefore, the oxidative deterioration of the contents due to oxygen permeation can be effectively suppressed, and excellent sliding properties can be maintained, and at the same time, excellent contents preservation can be ensured.

  As the above-mentioned ethylene vinyl alcohol copolymer, in general, an ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol%, particularly 25 to 50 mol%, has a saponification degree of 96 mol% or more, particularly A saponified copolymer obtained by saponification to be 99 mol% or more is preferred.

  Further, when a gas barrier resin is used as the intermediate layer 2, it is preferable to provide the intermediate layer 2 via an adhesive resin layer in order to improve adhesion with the inner and outer layers 3 and 1 and prevent delamination. As a result, the intermediate layer 2 can be firmly adhered and fixed to the inner and outer layers 3 and 1. A known resin can be used as the adhesive resin used to form the adhesive resin layer.

<Outermost layer 1 and innermost layer 3>
The outermost layer 1 and the innermost layer 3 of the present embodiment are made of, for example, a polyolefin-based resin. The polyolefin resin constituting the outermost layer 1 and the innermost layer 3 is not particularly limited, and examples thereof include low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene or the like is applicable. Further, random or block copolymers of α-olefins such as ethylene, propylene, 1-butene and 4-methyl-1-pentene are also applicable. In addition, low density polyethylene and linear low density polyethylene are suitable for imparting squeeze properties to the bottle and taking out the contents filled in the bottle from the bottle by squeezing.

  The thicknesses of the outermost layer 1 and the innermost layer 3 in the present embodiment are preferably set to such an extent that the functions of the respective layers are effectively exhibited and the thickness is not increased more than necessary. For example, in the outermost layer 1, the lubricant component effectively bleeds out on the surface and excellent transportability can be secured, and in the innermost layer 3, the lubricant component effectively bleed out on the surface and excellent sliding properties It is preferable to appropriately set according to the layer structure of the bottle so that the thickness of the entire bottle does not become unnecessarily thick.

<Lubricant>
As the lubricant to be added to the outermost layer 1 and the innermost layer 3, a solid polyhydric alcohol fatty acid ester having at least three hydroxyl groups and not fully esterified is used. Moreover, it is preferable that it is a polyhydric alcohol fatty acid ester less than 10 values from a viewpoint of the bleed-out property from a bottle. By using a lubricant of a polyhydric alcohol fatty acid ester that satisfies the above conditions, the bleed-out property of the lubricant is good, and the contents, in particular, thickeners such as thickening polysaccharides are added to give viscosity. The sliding property with respect to the contents is good, and the discharge performance of the contents can be maintained well. This is because when both the ester group and the hydroxyl group are present, good slipperiness can be obtained with respect to the content to which the thickener is added. Moreover, since it will be taken in in the content in the case of a liquid at normal temperature, it is preferable that it is solid at normal temperature. As such a polyhydric alcohol fatty acid ester, a diglycerin fatty acid ester having an esterification rate of 10 to 40% is particularly preferable from the viewpoint of bleed-out property and slipperiness with respect to the content having a thickener.

  The fatty acid is preferably a saturated fatty acid rather than an unsaturated fatty acid. This is because saturated fatty acids have a higher melting point than unsaturated fatty acids, and can have high slipping properties with respect to viscous contents containing a thickener. Examples of saturated fatty acids include stearic acid. Examples of unsaturated fatty acids include oleic acid.

  The content of the lubricant is preferably in the range of 0.05 to 5% by weight, particularly 0.1 to 1% by weight. That is, when the amount is smaller than this range, the amount of lubricant that bleeds out on the surface of the outermost layer 1 and the innermost layer 3 is reduced, so that good slipperiness is not imparted, and therefore the bottle transportability is also reduced. End up. In addition, when the lubricant is blended in a larger amount than the above range, the amount of bleed out is too large, and the line is soiled at the time of bottle molding, or the taste of the contents is affected.

  Further, the lubricant-containing layer containing the above-mentioned amount of lubricant may be formed in a layer located inside the above-described intermediate layer 2. Thereby, favorable slipperiness can be obtained with respect to the contents.

  Further, the lubricant-containing layer containing the above-mentioned amount of lubricant can be formed in a layer located outside the intermediate layer 2. In this case, for example, a configuration example in which a layer adjacent to the outermost layer 1 is further provided and a lubricant is added to the adjacent layer can be given.

  When the lubricant-containing layer is provided at a position adjacent to the outermost layer 1, it is preferable to use the same polyolefin-based resin as the polyolefin-based resin used for forming the outermost layer 1 as the resin for forming the layer. When using other resins, there is a risk that the adhesion between the outermost layer 1 and the lubricant-containing layer is reduced and delamination may occur, and in order to prevent such inconvenience, an adhesive resin layer is provided, This is because not only the cost is increased, but also the adhesive resin layer may reduce the transfer of the lubricant from the lubricant-containing layer to the outermost layer 1.

  In the above case, the repro (scrap resin) generated during the molding of the bottle can be blended with a virgin polyolefin-based resin and used as a resin for forming a lubricant-containing layer. In this case, from the viewpoint of reusing resources while maintaining moldability, the amount of repro is 10-60 parts per 100 parts by weight of virgin polyolefin resin (for example, the above-mentioned ultra-low density linear polyethylene). It is preferable that the amount is about parts by weight.

  A plastic bottle 100 according to the present embodiment shown in FIG. 1 has a multilayer structure of an outermost layer 1, an intermediate layer 2, and an innermost layer 3. However, the plastic bottle 100 of the present embodiment is not limited to the multilayer structure shown in FIG. 1, and can be configured with various layer configuration examples. For example, the adhesive resin layer can be AD, and the outermost layer / AD / gas barrier layer / AD / innermost layer can be exemplified as the outermost layer / AD / lubricant blocking layer / AD. Examples of layer structure of / repro layer / innermost layer can be given. The repro layer is a layer using repro (scrap resin) generated during molding of the plastic bottle of the present embodiment and a virgin polyolefin resin as a layer forming resin.

  In addition, it is possible to mix | blend each well-known various compounding agent, for example, a pigment, a ultraviolet absorber, etc. with each layer mentioned above in the range which does not impair the characteristic requested | required of each layer as needed. In the above description, the multilayered plastic bottle 100 has been described. However, a single-layered plastic bottle may be used.

  The plastic bottle 100 of the present embodiment can be molded by a known molding method, and can be molded by, for example, blow molding or injection molding.

  The plastic bottle 100 of the present embodiment is suitable for storing the contents of viscosity (for example, those having a viscosity at 25 ° C. of 100 cps or more) such as ketchup, various sauces, liquid glue, and mayonnaise. is there. This is because such a viscous content is desired to be able to be discharged out of the bottle without remaining on the inner surface of the bottle. Furthermore, in this embodiment, it can apply suitably to the content which added thickeners, such as a thickening polysaccharide, and gave the viscosity among such a viscous content.

  The plastic bottle 100 of the present embodiment can smoothly drop and discharge the contents even if the contents are viscous. In addition, since slipperiness is imparted by bleeding out of the lubricant to the outer surface of the bottle, it is possible to effectively prevent the bottles from sticking to each other and the adhesion between the bottle and the transporting material when transporting the bottle. Furthermore, when a layer structure is used in which a lubricant-containing layer containing a surfactant is blended at a position adjacent to the outermost layer 1, it is also effective to generate irregularities on the outer surface of the bottle during molding. Can be prevented.

  Next, examples of the plastic bottle 100 of the present embodiment will be described. In addition, the Example shown below is an example and this embodiment is not limited to the following Example.

In this example, a sheet having a thickness of 1.5 mm was extruded and molded using a base resin to which a lubricant described later was added. In addition, a single layer plastic bottle having a body thickness of 0.5 mm was molded by blow molding with the same configuration. The esterification rate in the lubricant is expressed by the following formula using the saponification value (SV), acid value (AV), and hydroxyl value (OHV) measured by the “standard oil and fat physical property test method” (established by Japan Oil Chemical Association). Calculated by
Esterification rate (%) = {(SV−AV) × 100} / (OHV + SV−AV)

Example 1
Using low-density polyethylene resin as the base resin, sheet A and diglycerin stearate ester (esterification rate is about 30%, melting point is solid at normal temperature) = 5000 ppm with a base resin added with a lubricant A single layer plastic bottle A was molded.

(Example 2)
Using the same base resin as in Example 1, diglycerin stearic acid ester (esterification rate is about 20%, melting point is solid at room temperature) = 5000 ppm using base resin to which a lubricant composed of 5000 ppm is added. And a plastic bottle B having a single layer structure was molded.

(Comparative Example 1)
Using the same base resin as in Example 1, diglycerin stearic acid full ester (esterification rate: 100% (full ester), melting point: solid at room temperature) = 5000 ppm added a base resin with a lubricant Sheet C and single-layer plastic bottle C were molded.

(Comparative Example 2)
Sheet D using a base resin similar to that in Example 1 and containing a lubricant composed of diglycerin oleate (esterification rate of about 30%, melting point liquid at room temperature) = 5000 ppm A plastic bottle D having a single layer structure was molded.

(Comparative Example 3)
Sheet E using the same base resin as in Example 1 and using a base resin added with a lubricant composed of decaglycerin oleate (esterification rate is about 80%, melting point is liquid at room temperature) = 5000 ppm And a plastic bottle E having a single layer structure was molded.

(Comparative Example 4)
Using the same base resin as in Example 1, monoglycerin oleate (esterification rate is about 30%, melting point is solid at room temperature) = 5000 ppm using a base resin to which a lubricant composed of 5000 ppm is added. And a plastic bottle F having a single layer structure was molded.

(Comparative Example 5)
Using the same base resin as in Example 1, molding sheet G and single layer plastic bottle G using a base resin with a lubricant composed of stearamide (melting point: solid at room temperature) = 5000 ppm did.

(Slip test)
After the sample sheet formed in Examples 1 and 2 and Comparative Examples 1 to 5 had an oil content of 60% by mass or less and 5 g of mayonnaise-like food containing a thickener was placed in a dome shape, the sample sheet was 55 °. The sample was fixed at an inclination, and the degree of craving generated at the interface between the sample sheet and the mayonnaise-like food and the sliding distance after standing for 10 minutes were visually observed. Moreover, after filling about 1/3 of the total volume of mayonnaise-like food into each plastic bottle, the state of the mayonnaise-like food adhering to the wall surface was visually observed by shaking the bottle.

(Evaluation judgment)
The determination of the slipperiness of the mayonnaise-like food was evaluated as ○, Δ, and × from the results of good repelling condition and sliding distance of the mayonnaise-like food on the sample sheet by visual observation. Moreover, the evaluation in the plastic bottle was evaluated as ◯, Δ, and X.

  The above-described embodiments and examples are preferred embodiments and examples of the present invention, and the scope of the present invention is not limited only to the above-described embodiments and examples, and does not depart from the gist of the present invention. Implementation in a form in which various changes are made in the range is possible.

  For example, in the above-described embodiment, in order to obtain good slipperiness with respect to the contents, a glycerin fatty acid ester-based lubricant that is solid at room temperature is added to the base resin in contact with the contents. However, it is also possible to add a lubricant, which is a mixture of glycerin fatty acid ester that is solid at normal temperature and glycerin fatty acid ester that is liquid at normal temperature, to the base resin in contact with the contents.

  Glycerol fatty acid esters that are solid at room temperature are more difficult to bleed out than glycerin fatty acid esters that are liquid at room temperature, but glycerin fatty acid esters that are liquid at room temperature are less entangled with resin molecules. When used at the same time, bleed-out can be promoted by bleeding out the solid glycerin fatty acid ester with the bleed-out of the liquid glycerin fatty acid ester.

  In addition, by using a solid glycerin fatty acid ester that is difficult to bleed out, the bleedout can be appropriately advanced compared to a liquid glycerin fatty acid ester alone, so that film formation is possible compared to the case of using only a liquid glycerin fatty acid ester alone. Bleed-out immediately after is suppressed, and adhesion of the release agent on the production line can be suppressed. Also, bottle powder blowing problems due to solid glycerin fatty acid ester, stickiness of the line, and slip are alleviated, and bottle line running performance is reduced. Can be improved.

  The difference in melting point between the two types of glycerin fatty acid esters is preferably 10 ° C. or higher, and more preferably 40 ° C. or higher for improving line suitability and peelability when filling the contents. The melting point of the liquid glycerin fatty acid ester is preferably 10 ° C. or lower, and more preferably 0 ° C. or lower. Further, the melting point of the solid glycerin fatty acid ester is preferably 30 ° C. or higher, and more preferably 50 ° C. or higher.

  The blend ratio of glycerin fatty acid ester which is liquid at normal temperature and glycerin fatty acid ester which is solid at normal temperature is preferably 4: 1 to 1: 4. If the blend ratio of glycerin fatty acid ester solid at room temperature is too large, the amount of bleedout immediately after film formation will be insignificant, and it will not be suitable for peeling the contents, and the viscosity of glycerin fatty acid ester will be too high, This is because the glycerin fatty acid ester adhering to the line deteriorates the running performance of the bottle. Moreover, if the ratio of the glycerin fatty acid ester that is liquid at room temperature is too large, the amount of bleed-out will increase so much that the glycerin fatty acid ester will adhere to the bottle, which will adversely affect the running performance of the line.

100 Plastic bottle 1 Outermost layer 2 Middle layer 3 Innermost layer

Claims (5)

At least three or more hydroxyl groups are added to the base resin constituting the layer in contact with the contents, and a room temperature solid polyhydric alcohol fatty acid ester that is not fully esterified is added ,
The base resin contains a liquid polyhydric alcohol fatty acid ester,
The plastic container , wherein a blend ratio of the normal-temperature solid polyhydric alcohol fatty acid ester and the liquid polyhydric alcohol fatty acid ester is 4: 1 to 1: 4 .   The plastic container according to claim 1, wherein the polyhydric alcohol fatty acid ester is a diglycerin fatty acid ester.   The plastic container according to claim 1 or 2, wherein the polyhydric alcohol fatty acid ester is obtained by esterifying a saturated fatty acid.   The plastic container according to claim 3, wherein the saturated fatty acid is stearic acid.   The plastic container according to any one of claims 1 to 4, wherein the polyhydric alcohol fatty acid ester is less than 10 valences.

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