WO2016158875A1 - Structure having hydrophobic surface, and method for manufacturing same - Google Patents

Abstract

A structure including: a molded body, the surface of which being formed from a base resin layer 1; and microparticles distributed on the base resin layer 1 on the surface of the molded body, wherein the structure is characterized in that wax 3 is distributed on the surface of the base resin layer 1 together with microparticles 7, and some of the wax 3 is absorbed into the base resin layer 1.

Description

Structure having hydrophobic surface and method for producing the same

The present invention relates to a structure having a hydrophobic surface, and more particularly, to a structure in which a hydrophobic uneven surface is formed by fine particles being distributed on the surface. Also relates to its production method.

Plastics are easy to mold and can be easily molded into various forms, and thus are widely used for various applications. For example, various viscous beverages, cooking oils, seasonings, or yogurt It is suitably used as a container for storing various foods, and liquid detergents and pastes.

By the way, in a container in which liquid contents or gel-like contents are stored, it is possible to effectively prevent the contents from remaining on the inner surface of the container (non-adhesiveness of the contents), or to quickly remove the contents from the container. In many cases, it is required to be discharged (sliding property of contents).

Means for enhancing non-adhesion and sliding properties (hereinafter, these properties may be referred to as slipperiness) to the contents include distributing hydrophobic fine particles on the surface in contact with the contents, Means such as coating with a solid wax is known (see, for example, Patent Documents 1 to 3).
That is, these well-known means provide excellent slipperiness to the contents containing moisture by allowing hydrophobic fine particles and solid wax to be present on the surface in contact with the contents. It is. In particular, when the hydrophobic fine particles are distributed on the surface, irregularities are formed on the surface, thereby greatly improving the slipperiness with respect to the contents. That is, when the contents move on the uneven surface, the contents move while in contact with the air existing between the unevenness, but the air has the highest water repellency. Therefore, the water repellency exhibited by the hydrophobic fine particles and the water repellency due to the unevenness are combined to greatly increase the slipperiness to the contents.

JP2012-228787A Patent No. 5490574 Patent No. 4348401

However, all of the conventionally known means using hydrophobic fine particles or solid wax use a coating solution in which these components are dissolved in an organic solvent, and this coating solution is applied to the surface and dried. Therefore, there has been a problem that the burden on the environment is great for removing the solvent.

Accordingly, it is an object of the present invention to provide a structure having a hydrophobic surface formed using fine particles and wax but without using any organic solvent.
Another object of the present invention is to provide a method for producing a structure having a hydrophobic surface as described above.

According to the present invention, in a structure including a molded body having a surface formed of a resin layer and fine particles distributed on the resin layer on the surface of the molded body,
A structure is provided in which wax is distributed together with fine particles on the surface of the resin layer, and a part of the wax is absorbed in the resin layer.
In this specification, the molded body means that the surface is formed of a resin layer (underlying resin layer), and the structure means that fine particles and wax are distributed in the resin layer on the surface of the molded body. Further, it means that the surface resin layer absorbs wax.

In the structure of the present invention, the following aspects are preferably employed.
(1) using hydrophobic fine particles as the fine particles,
(2) A metaball solid layer in which the wax is continuous in a metaball shape is formed on the resin layer, and the fine particles are distributed inside the metaball solid layer.
(3) The three-dimensional metaball layer has a ball-connected structure having a diameter of 20 to 200 nm as observed with a scanning electron microscope.
(4) The fine particles have an average primary particle size of 4 nm to 1 μm.
(5) The melting point of the wax is in the range of 40 ° C to 110 ° C.
(6) The resin forming the resin layer has an SP value difference of 1.5 (MPa) ^1/2 or less from the wax.
(7) The resin forming the resin layer is an acyclic olefin resin, and the wax is at least one of paraffin wax, microcrystalline wax, or polyethylene wax.
(8) The molded body has the form of a container, and the fine particles and wax are distributed on the inner surface on the side in contact with the contents contained in the container.
(9) The container is a bottle made of olefin resin.
(9) The molded body has a form of a lid material applied to the container mouth by heat sealing, and the fine particles and the wax are distributed on the surface in contact with the contents contained in the container. Doing things.

Moreover, according to the present invention, a step of preparing a non-solvent coating composition containing fine particles and molten wax, and a molded body having a surface formed of a layer of a wax-absorbing resin;
A coating step of coating the non-solvent coating composition on the surface of the molded body;
Next, the surface of the molded body is heated to a temperature equal to or higher than the melting point of the wax to maintain the state in which the wax is melted, whereby the wax-absorbing resin layer on the surface absorbs the wax.
and,
A cooling step of solidifying the molten wax by cooling the surface of the molded body after the wax absorption step;
A method for producing a structure having a hydrophobic surface is provided.

In the above manufacturing method,
(1) The wax-absorbing resin has a difference in SP value from the wax of 1.5 (MPa) ^1/2 or less,
(2) In the wax absorption step, when the melting point of the wax-absorbing resin is X ° C., heating for maintaining the wax in a molten state is performed by the following conditional formula:
X-5 ≧ Y ≧ X-50
For 5 seconds to 10 minutes at a temperature Y satisfying
Is preferred.

According to the present invention, when a molded body having a surface formed by the wax-absorbing resin layer is produced by extrusion molding using the wax-absorbing resin, it is adjacent to the wax-absorbing resin layer. A method for producing a structure having a hydrophobic surface is provided by coextruding a non-solvent composition containing fine particles and molten wax at a position on the surface side.

In the structure of the present invention, wax is absorbed in a resin layer (hereinafter referred to as an underlayer) on the surface of the molded body, and fine particles are distributed on such an underlayer, and are derived from such fine particles. In addition, a hydrophobic uneven surface is formed on the surface of the structure, and thereby the slipperiness with respect to the moisture-containing substance is greatly improved.

The hydrophobic uneven surface formed on the wax-absorbing underlayer as described above can be formed without using an organic solvent, which is the greatest advantage of the present invention.
Specifically, a molded body having a surface formed of a wax-absorbing resin is molded, and a coating composition in which fine particles are dispersed in a molten wax is applied on the surface, and then the wax Heat above the melting point. As a result, the wax is absorbed in the base layer on the surface of the molded body, and the fine particles adhere to the surface and are distributed.

According to the above method, the degree of unevenness of the hydrophobic uneven surface formed on the surface of the base resin layer can be adjusted by adjusting the heating time, heating temperature and the like. For example, the longer the heating time or the higher the heating temperature, the greater the amount of wax absorbed from the coating composition into the wax-absorbing underlayer.

That is, when most of the wax in the coating composition is absorbed in the undercoat layer, a thin wax layer is formed on the surface of the undercoat layer, and fine particles protrude from the thin wax layer. An uneven surface is formed. The fine particles protruding from the thin wax layer may be exposed in some cases, or in some cases, may protrude with the wax layer formed on the particle surface. The degree of unevenness of the surface greatly depends on the particle size of the fine particles.
In addition, by forming the hydrophobic fine particles to be small in size and limiting the amount of wax absorbed into the underlayer to some extent, a metaball solid layer in which the wax is continuous in a metaball shape is formed on the underlayer. Can do. Fine particles are distributed inside such a metaball three-dimensional layer, and a hydrophobic uneven surface is formed by such a metaball three-dimensional layer. On such a hydrophobic uneven surface, a plurality of fine particles are distributed inside one metaball connected to each other. In the present invention, the highest slipping property is exhibited.

Further, in the present invention, a hydrophobic uneven surface in which fine particles are distributed on the surface of the base layer in which the wax is absorbed can be formed by utilizing coextrusion.
That is, when forming a molded body having the resin layer on the surface by extrusion molding by extruding a wax-absorbing resin melt, the wax melt is placed in a position adjacent to the resin layer and on the surface side. A non-solvent composition in which fine particles are dispersed is coextruded. As a result, the wax, which is a dispersion medium for the fine particles, is absorbed in the adjacent resin layer (underlying layer), and a hydrophobic uneven surface having fine particles distributed on the surface can be formed.
Also by such a method, a hydrophobic uneven surface can be formed without using an organic solvent. In the hydrophobic uneven surface thus formed, the hydrophobic uneven surface is formed by the metaball solid layer in which fine particles are distributed in the same manner as described above.

As described above, the hydrophobic irregular surface due to the fine particles of the structure of the present invention described above can be formed without using an organic solvent, and this is the collection of the organic solvent that evaporates upon heating. This eliminates the need for such a burden, greatly increases production efficiency and reduces costs, avoids adverse effects on the environment, and is extremely advantageous for industrial implementation.
Moreover, the hydrophobicity of the surface is further enhanced by using hydrophobic fine particles to which hydrophobicity is imparted as the fine particles.

The schematic sectional drawing which shows the most suitable hydrophobic uneven | corrugated surface currently formed in the surface of the structure of this invention. The schematic sectional drawing which shows the other example of the hydrophobic uneven surface formed in the surface of the structure of this invention. The schematic sectional drawing which shows the example of the hydrophobic surface of a form different from the hydrophobic uneven | corrugated surface formed in the surface of the structure of this invention. The figure which shows the form of the direct blow bottle which is a suitable form of the structure of this invention. In Example 1, the three-dimensional image obtained by implementing surface shape measurement using an atomic force microscope before a heating process. In Example 1, the three-dimensional image obtained by implementing surface shape measurement using an atomic force microscope after a heating process. In Example 1, the observation image (10,000 times) obtained by implementing surface observation using a scanning electron microscope before a heating process. In Example 1, the observation image (100,000 times) obtained by implementing surface observation using a scanning electron microscope before a heating process. In Example 1, the observation image (10,000 times) obtained by implementing surface observation using a scanning electron microscope after a heating process. In Example 1, the observation image (100,000 times) obtained by implementing surface observation using a scanning electron microscope after a heating process. In Example 2, the observation image (10,000 times) obtained by implementing surface observation using a scanning electron microscope after a heating process. In Example 2, the observation image (100,000 times) obtained by implementing surface observation using a scanning electron microscope after a heating process. In Example 2, the observation image obtained by implementing cross-sectional observation using a transmission electron microscope after a heating process. In Example 3, the observation image (10,000 times) obtained by implementing surface observation using a scanning electron microscope after a heating process. In Example 3, the observation image (100,000 times) obtained by implementing surface observation using a scanning electron microscope after a heating process. The SEM photograph of the uneven | corrugated surface structure produced in each experiment. The measurement result of the endothermic peak in Experiment 1 is shown. The measurement result of the endothermic peak in Experiment 2 is shown. The measurement result of the endothermic peak in Experiment 3 is shown.

<Surface structure of structure>
Referring to FIG. 1 showing the most preferable surface structure of the structure of the present invention, the structure 10 as a whole has a wax-absorbing property formed on the surface of a molded body molded into a predetermined shape. A base resin layer 1 (base layer) made of a resin is included. The base layer 1 absorbs the wax 3, and the metaball solid layer is formed on the base layer 1 in which the wax 3 is absorbed. 5 is formed.
This metaball three-dimensional layer 5 has a form in which spherical metaballs 5a formed of the wax 3 are connected in a three-dimensional manner, and as can be understood from FIG. 1, in one metaball 5a, A plurality of fine particles 7 are distributed. A hydrophobic uneven surface is formed by such a metaball solid layer 5.
The diameter (equivalent circle diameter) of the metaball 5a in the metaball solid layer 5 is preferably in the range of 20 to 200 nm, particularly 50 to 150 nm as measured with a scanning electron microscope. Further, since the three-dimensional layer 5 is formed by connecting the metaballs 5a, there are voids 9 inside. Such a metaball three-dimensional layer 5 has an uneven surface with a high degree of unevenness including voids inside, and is formed of the hydrophobic wax 3, thus exhibiting high hydrophobicity, a water-containing substance and a hydrophilic substance. Exhibits extremely high slipperiness against substances.

The above-described metaball three-dimensional layer 5 uses a non-solvent coating composition (that is, does not contain a solvent) containing fine particles 7 and a wax 3 in a molten state, and the composition is coated on the underlayer 1. The surface of the underlayer 1 is heated so that the molten state of the wax 3 is maintained, and a part of the wax 3 is absorbed by the underlayer 1 and then cooled.

That is, the metaball three-dimensional layer 5 forming the hydrophobic uneven surface is formed for the first time by absorbing the wax 3 in the base resin layer 1 in a state where the fine particles 7 coexist with the wax 3 in a molten state. It is a very specific structure. The melted wax 3 exists in a state of containing a plurality of fine particles 7, and the wax 3 is absorbed by the underlayer 1 in this state. 3 is preferentially absorbed by the underlayer 1, and the wax 3 located in the vicinity of the fine particles 7 remains on the underlayer 1 together with the fine particles 7.
Accordingly, when the wax 3 melted in this state is cooled and solidified, a connection structure of the metaballs 5a of the wax 3 having a smooth surface or a spherical shape having a smooth surface is formed. In addition, a plurality of fine particles 7 are distributed inside the metaball 5a, and voids 9 are formed between the metaballs 5a. Thus, the three-dimensional metaball layer 5 formed on the base layer 1 in which the wax 3 is absorbed has a structure including the wax 3 and the gap 9. The shape of such a metaball is similar to, for example, a space-filling model widely used for spatially indicating the chemical structure of a substance.
Formation of the metaball three-dimensional layer 5 can be confirmed by an atomic force microscope or a scanning electron microscope, as shown in the examples described later.

Further, as understood from the above description, when the coating of the non-solvent coating composition containing the fine particles 7 and the wax 3 in a molten state is further heated after the metaball three-dimensional layer 5 is formed, The molten wax 3 present around the fine particles 7 falls to the surface side of the underlayer 1. As a result, as shown in FIG. 2, a thin layer 3a of the wax 3 is formed on the base layer 1 absorbing the wax 3, and the fine particles 7 are distributed in a state of protruding from the thin layer 3a. Will be. In the portion of the fine particle 7 protruding from the thin layer 3a, the surface of the fine particle 7 is exposed or a minute amount of wax 3 is present covering the surface.
Even in such a surface structure, a hydrophobic uneven surface is formed, and compared with the above-described metaball three-dimensional layer 5, the degree of unevenness is low and the void 9 is not included therein, so that it is inferior in terms of slipperiness. However, the fine particles 7 can be stably held, and the slipperiness can be stably exhibited over a long period of time. In general, the thickness of the thin layer 3a is preferably in the range of about 2 nm to 1 μm from the viewpoint of ensuring slipperiness and retention of the fine particles 7.

In addition, when the wax 3 is continuously heated from the state shown in FIG. 2 and kept in a molten state, the wax 3 forming the thin layer 3a is also absorbed by the base resin layer 1, and as a result, Only the fine particles 7 remain on the surface of the underlayer 1. Even in this state, the hydrophobic uneven surface is formed by the fine particles 7 distributed on the surface, and the surface of the underlayer 1 includes the wax 3 exhibiting hydrophobicity. Compared with the embodiment of FIG. 2, the fine particles 7 are likely to fall off and are not suitable for exhibiting slipperiness over a long period of time.

When a coating composition using an organic solvent is used, the wax 3 is deposited simultaneously with the volatilization of the organic solvent. Therefore, the wax 3 is not absorbed by the underlayer 1, and as a result, as shown in FIG. As shown, the surface layer 5 in which the fine particles 7 are distributed in the wax 3 is merely formed on the underlayer 1, and there are no voids in the surface layer 5. As compared with the structure 10 of the present invention which does not have an uneven surface and therefore has the surface structure shown in FIGS. 1 and 2, its hydrophobicity is extremely inferior.

Wax-absorbing base resin layer (base layer) 1;
In the present invention, the underlayer 1 is capable of absorbing wax (hydrocarbon wax, ester wax, etc.). The wax absorptivity of the underlayer 1 can be determined whether or not there is absorptivity by melting the wax to be used and applying it on the underlayer 1 and confirming the absorbency (volume change). The resin used for the underlayer 1 can be selected according to the type of wax used. Also, the type of wax can be selected according to the type of resin used for the underlayer 1.

In the present invention, generally, the hydrophobicity is high (for example, the contact angle with water (measured at 23 ° C.) is 70 degrees or more, particularly preferably 85 degrees or more), and the molecular chain contains a polar group. In addition, it is preferable to form the underlayer 1 using a thermoplastic resin having a relatively loose structure and not having a crosslinked structure, specifically, an olefin-based or polyester-based resin. is there.

Examples of such olefin-based and polyester-based resins include low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, or ethylene, propylene, 1-butene, 4-methyl- Random or block copolymers of α-olefins such as 1-pentene, (meth) acrylic acid, (meth) acrylic acid ester, vinyl acetate, cyclic olefin copolymers, and polyester resins include polyethylene terephthalate, polybutylene Examples thereof include terephthalate, polyethylene naphthalate, and polylactic acid, and these can be blended and used as necessary.

The resin forming the underlayer 1 has a molecular weight that can form at least a film, but an extremely high molecular weight (such as ultra-high molecular weight polyethylene) has almost no absorbency of wax. It will stop showing. Therefore, it is generally better to use one having a normal extrusion grade melt flow rate (MFR).

Furthermore, in the present invention, as the resin for forming the underlayer 1, among the above-described various thermoplastic resins, those having an SP value difference with the wax 3 of 1.5 (MPa) ^1/2 or less are particularly preferred. It is best to use.
This SP value is an index called a solubility parameter -δ calculated by the calculation method proposed by Small, calculated from the molar traction force constant and molecular volume of the atoms or atomic groups constituting the molecule and their bond type. (PAJ Small: J. Appl Chem., 3, 71 (1953)). By the way, such SP value is widely used as a scale for evaluating the compatibility between substances. The smaller this difference is, the higher the affinity between both substances is, and the higher the compatibility is. ing.
That is, when a resin having an SP value close to that of the wax 3 as described above is used, the affinity with the wax 3 is extremely high, so that the wax 3 in the underlayer 1 can be easily absorbed. It is extremely suitable for forming the above-described three-dimensional metaball layer 5.

Incidentally, SP values of paraffin wax and typical thermoplastic resins are as follows.
SP value (MPa) ^1/2 Difference in SP value Paraffin wax 17.3 0
Polyethylene (LDPE) 17.9 0.6
Polyethylene (HDPE) 18.7 1.4
Homopolypropylene (h-PP) 16.4 0.9
Cyclic olefin copolymer (COC) 13.8 3.5
Ethylene vinyl alcohol copolymer (EVOH)
18.9 1.6
Polyethylene terephthalate (PET)
22.7 5.4
PET-G 20.4 3.1
PET-G is amorphous polyethylene terephthalate, which is a copolymerized polyethylene terephthalate containing a copolymer component.

Therefore, when paraffin wax is used as the wax 3, an acyclic olefin resin such as polyethylene or polypropylene can be suitably used as the resin for forming the base layer 1 on the surface of the molded body.

Further, the resin having a difference in SP value with respect to the wax 3 in the above range varies depending on the type of the wax 3 to be used, but since the SP value of the wax 3 is substantially the same as that of the paraffin wax, in general, Acyclic olefin resins such as low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene or ethylene, propylene, 1-butene, 4-methyl-1-pentene, (meta Examples thereof include random or block copolymers of α-olefins such as acrylic acid, (meth) acrylic acid ester, and vinyl acetate.
Further, even if the resin has a large SP value difference with the wax 3 such as a cyclic olefin copolymer (COC), it is blended with a resin having a small SP value difference, and the difference in the SP value in a blended state. Is 1.5 (MPa) 1/2 or less, the resin for the underlayer 1 can be used.

The thickness of the wax-absorbing underlayer 1 as described above is not particularly limited, but in general, it preferably has a thickness of about 5 to 200 μm, particularly about 10 to 100 μm. If this thickness is too thin, the amount of absorption of the wax 3 decreases, and as a result, the metaball three-dimensional layer 5 becomes difficult to be formed, and the hydrophobic effect due to surface irregularities may be reduced. Further, when the thickness of the underlayer 1 is larger than necessary, almost all of the used wax 3 is easily absorbed by the underlayer 1, and for example, a structure as shown in FIG. 1 or FIG. 2 is formed. It may be difficult to control. That is, the structure in which the fine particles 7 are distributed directly on the surface of the underlayer 1 tends to be reduced, the holding power of the fine particles 7 is reduced, the particles 7 are liable to fall off, and it is difficult to ensure stable slipperiness. .

Furthermore, in the present invention, in order to effectively utilize the wax-absorbing ability of the wax-absorbing underlayer 1 described above, the crystallinity is 60% under a temperature condition in which the underlayer 1 absorbs the wax 3 in a molten state. In the following, it is preferable to select a resin that is preferably 50% or less and use it as the resin for the base layer 1 (base resin). In other words, it is preferable that the wax 1 in the molten state is absorbed by the base layer 1 at a temperature lower than the melting point of the base resin while maintaining the crystallinity within such a range. That is, if the base layer 1 absorbs the molten wax 3 in a state where the crystallinity of the base resin is high, even if the resin has good compatibility with the wax 3, the crystal component is Since there are many, the absorbability of the wax 3 is reduced, the amount of absorbed wax is insufficient, the formation of the metaball three-dimensional layer 5 as shown in FIG. 1 is difficult, and the thin wax 3 as shown in FIG. The structure in which the fine particles 7 protrude from the layer 3a may not be formed.
The crystallinity of the base resin can be measured from the DSC temperature rise curve of the resin. Therefore, based on this curve, the crystallinity is in the temperature range where the crystallinity falls within the above range and below the melting point of the resin. The wax 3 may be absorbed by the underlayer 1 at a temperature.

Wax 3;
The wax 3 used in the present invention is used as a dispersion medium for the fine particles 7. At the same time, even in the form distributed on the surface of the underlayer 1, the wax 3 exhibits hydrophobicity and does not inhibit its slipperiness. It has characteristics.
For example, paraffin wax is a white solid at normal temperature produced from a petroleum refining process, and is mainly composed of linear paraffin having about 20 to 30 carbon atoms and a small amount of isoparaffin.
As an example of the plant wax, carnauba wax is a light yellow to light brown solid collected from carnabay palm, and mainly contains a hydroxy acid ester having 16 to 34 carbon atoms.

In the present invention, among such waxes 3, those having a melting point in the range of 50 to 100 ° C. are particularly suitable. That is, if the melting point of the wax 3 is too low, the wax 3 flows during the use of the structure 10 in summer and the like, and at the same time, the metaball three-dimensional layer 5 in FIG. 1 and the wax 3 shown in FIG. The thin layer 3a may fall off. On the other hand, if the melting point of the wax 3 is too high, the heating temperature for absorbing the wax 3 into the base layer 1 must be high, and the operation is limited to extrusion molding, or the base layer of the wax 3 It may be difficult to effectively absorb 1.
In the present invention, synthetic hydrocarbon waxes, plant waxes, animal waxes, mineral waxes and the like can also be used on the condition that the melting point is within the above range.

Furthermore, the wax 3 used in the present invention is preferably paraffin wax, polyethylene wax, or microcrystalline wax, for example, when an acyclic olefin resin is used for the underlayer 1. That is, these waxes have a difference in SP value from the non-cyclic olefin resin as the base resin in the above-described range, and show high compatibility with the base layer 1. Further, since the speed at which the wax 3 is absorbed by the underlayer 1 is a diffusion process, the absorption speed is slower as the molecular weight is larger, depending on the molecular weight of the wax 3. The average molecular weight (Mn) of the wax 3 used in the present invention is 10,000 or less, preferably 5000 or less, and most preferably 1000 or less.

In the present invention, it can be confirmed that the wax 3 is absorbed in the underlayer 1 by comparing the DSC temperature rise curve of the underlayer 1 with that of the underlayer resin alone. That is, when the wax 3 is absorbed in the underlayer 1, an endothermic peak (which may appear as a shoulder depending on the amount of absorption) is formed in a lower temperature range than the melting point of the underlayer resin alone. Can be confirmed. Moreover, it can also confirm by performing extraction from the base layer 1 using a solvent.

Fine particles 7;
The fine particles 7 in FIG. 1 are used as a roughening material, and are an essential material for forming the metaball-shaped wax layer 5. That is, if the base layer 1 only absorbs the wax 3 and forms the wax layer 5 on the base layer 1, such a fine particle 7 is not blended, and the melt of the wax 3 is added to the base layer 1. Just apply. However, in this case, since the wax layer 3 does not have a metaball shape, the surface of the wax layer 5 does not become an uneven surface. Therefore, it is necessary to form an uneven surface by post-treatment such as blasting or etching. Although it is possible to ensure slipperiness by such means, in this case, a special apparatus for post-processing is required, and the wax layer 5 is formed without using an organic solvent. As a result, the advantage of the present invention that the cost can be reduced is diminished. In addition, there is a restriction that the molded body provided with the base layer 1 must have a form suitable for post-processing. For example, when the molded body has a form like a bottle, post-processing is performed. Becomes difficult. Furthermore, even if the wax layer 5 having an uneven surface can be formed, a metaball shape having voids 9 therein is not formed, so that the slipperiness is also inferior to the wax layer 5 in the form of FIG. It becomes a thing.
Therefore, in the present invention, it is most preferable to use the fine particles 7 as a roughening material to form a metaball-shaped wax layer 5 as shown in FIG.

The fine particles 7 used as the roughening material are blended into the melt of the wax 3 and when the melt is applied to the base layer 1, the particulate layer 7 maintains the granular shape in the base layer 1. As long as it remains on the underlying layer 1 without being absorbed, in general, particles of inorganic oxides such as silica, titanium oxide, and alumina, and particles of carbonates such as calcium carbonate are suitable. used.

In order to form the metaball-shaped wax layer 5 in which the diameter (equivalent circle diameter) of the metaball 5a is in the above-mentioned range (20 to 200 nm, particularly 50 to 150 nm), among the fine particles 7 as described above, The primary particle size (or minimum structural unit) is desirably in the range of 3 nm to 1 μm, preferably 5 nm to 500 nm, more preferably 10 nm to 200 nm. In the present invention, it is presumed that the fine particles 7 act as a core of the metaball 5a forming the metaball-shaped wax layer 5, and the size of the metaball is considered to depend on the primary particle size of the fine particles 7 to be used. Because it is. Therefore, in the present invention, in order to form the metaball-shaped wax layer 5 exhibiting excellent slipperiness with respect to the content containing moisture, it is preferable to use fine particles 7 having an average primary particle diameter in the above range. .
The average primary particle diameter of the fine particles 7 can be measured by observation with a scanning electron microscope.

The surface of the fine particles 7 as described above is a functional group having a critical surface tension of 30 mN / m or less, for example, an alkyl group such as a methyl group, an alkylsilyl group such as a methylsilyl group, a fluoroalkyl group, or a fluoroalkylsilyl group. It is preferably modified to be hydrophobized. By introducing such a hydrophobic functional group, for example, when the fine particles 7 are dispersed in the wax 3 in a molten state, good dispersion is obtained, and the wax 3 is retained in the vicinity of the fine particles 7, and the The wax layer 5 having a shape can be easily formed, and the wax layer 5 having no partial defects can be formed uniformly.
For example, in the present invention, when 20 μL of pure water is dropped on the surface of the wax layer 5 formed by the connection of the metaballs 5 a including the hydrophobic fine particles 7, the angle of the surface where the pure water slides down is as follows. The defined falling angle can be 5 ° or less, and the slipperiness with respect to the viscous content containing moisture can be remarkably enhanced.

Such modifications with hydrophobic functional groups include coupling using a hydrophobizing agent having these functional groups (for example, silane compounds, siloxane compounds, silazane compounds, titanium alkoxide compounds, etc.), fatty acids, metal soaps, etc. This is done by the coating used.

In the present invention, the hydrophobic fine particles 7 that are particularly preferably used are hydrophobic silica fine particles and calcium carbonate fine particles due to cost and availability, and are surface-modified with dimethylsilyl groups or trimethylsilyl groups, or silicone oils. Hydrophobic silica fine particles that are surface-coated with, or calcium carbonate fine particles that are surface-coated with a fatty acid or metal soap are most preferred.

The fine particles 7 described above are distributed in the metaballs 5a forming the wax layer 5 as shown in FIG. 1, but such a surface structure can be easily formed. The amount of surface distribution varies depending on the primary particle size, but generally 30 to 900 mg / m ² , particularly 300 to 600 mg / m ² . It is preferable to be in the range.

Formation of a surface structure having a hydrophobic uneven surface;
The hydrophobic uneven surface forming the surface structure of the structure 10 of the present invention described above is a non-solvent coating composition (hereinafter referred to as a wax composition) containing fine particles 7 and a melted wax 3 as described above. (Referred to as an object). That is, a molded body having a wax-absorbing base layer 1 on the surface is molded in advance, and a wax composition containing the wax 3 in a molten state is sprayed on the surface of the molded body, spray coating, roller coating, knife coating, etc. Further, the structure 10 having the target surface structure can be obtained by further heating and holding the surface so that the molten state of the wax is maintained, and absorbing the wax 3 in the surface underlayer 1 on the surface. (Hereinafter, this method is referred to as a coating method).

In the above coating method, it is essential that the heating temperature for absorbing the wax 3 in the molten state into the base layer 1 is not less than the melting point of the wax 3, and in particular, the glass transition temperature (Tg) of the base resin layer 1. It is preferable that the temperature is lower than the melting point of the base resin. However, as described above, the temperature at which the crystallinity of the base resin is not more than a predetermined range is preferable.
Specifically, when the melting point of the base resin is X ° C., the heating temperature Y is expressed by the following conditional expression:
X-5 ≧ Y ≧ X-50
It is more preferable to set so as to satisfy the above, and it is more preferable to heat and hold the wax melt at such a temperature for 5 seconds to 10 minutes, particularly for about 10 seconds to 5 minutes. That is, if the heating temperature Y ° C. is too low with respect to the melting point X ° C. of the base resin, many crystals remain in the base layer 1, and the remaining crystals inhibit the absorption of the wax 3 into the base layer 1. In addition, it takes a long time to form the wax layer 5 having the form shown in FIG. 1, which tends to be disadvantageous in terms of productivity. When the heating temperature Y ° C. is performed in a state close to the melting point X ° C. of the base resin, the absorption speed of the wax 3 is too high, and most of the wax 3 in the melt is absorbed into the base layer 1 in a short time. Consequently, as a result, it tends to be difficult to ensure the amount of the wax 3 on the base layer 1 necessary for forming the wax layer 5 having the form shown in FIG. Incidentally, the crystallinity of the base resin under a heating condition that satisfies the above conditions is 60% or less, particularly 5 to 50%. The crystallinity of the base resin under such heating conditions can be calculated from, for example, a crystal melting peak obtained from a DSC temperature rise curve.

Note that this heating can also be performed after the wax in the wax composition applied to the surface is cooled and solidified.

In such a coating method, the surface structure as described above can be easily formed on the entire surface of the structure 10 (molded body). However, by selectively setting the application position of the wax composition, the structure The surface structure as described above can be formed only on a part of the surface of the body 10.

In the present invention, the surface structure described above can also be formed by a coextrusion method.
In this method, the above-described surface structure and the underlayer 1 are coextruded with the wax-absorbing base resin and the wax composition so that the wax composition is adjacent to the surface side of the base resin layer. It is possible to perform molding of the molded body provided with In this case, since both the wax 3 and the base resin in the wax composition are adjacent to each other in a molten state, the wax 3 is quickly absorbed into the base layer 1, and the wax 3 is used as the base layer. 1 has the advantage that no special heat treatment is required for absorption. However, in this method, as shown in FIG. 2, it is easy to form a surface structure in which hydrophobic fine particles 7 protrude and are distributed from the thin layer 3 a of the wax 3. It is difficult to form such a metaball three-dimensional layer 5. This is because it is difficult to control the temperature after extrusion.

In the above-described coating method and co-extrusion method, the concentration of the hydrophobic fine particles 7 in the wax composition to be used can be easily applied or co-extruded using this composition. Alternatively, the surface structure of FIG. 2 is set so as to be easily formed, and is usually 50 parts by mass or less, particularly 3.0 to 10.0 parts by mass, most preferably 5.0 to 8. About 0 parts by mass.
In the present invention, a predetermined surface structure can be formed without using an organic solvent by any of the above methods.

A layer structure of the structure 10;
In the structure 10 of the present invention, the wax 3 described above is absorbed in the base layer 1 on the surface of the molded body formed into a predetermined shape, and the surface structure shown in FIG. 1 or 2 is formed on the surface of the base layer 1. As long as it is formed, it can take various forms.

For example, the above-mentioned molded body is a single-layer structure made only of the base resin that forms the base layer 1, and the surface structure shown in FIG. 1 or 2 may be formed on the surface of the single-layer structure. It is also possible to use a structure in which the underlayer 1 is formed on the surface of glass, metal foil, paper, or the like as a molded body. In particular, when the structure 10 of the present invention is used as a lid for a container, a structure in which the base layer 1 is laminated on paper or metal foil is often used as a molded body.

Furthermore, in the present invention, a multilayer structure in which the base layer 1 is laminated with another resin layer can be used as a molded body, and the surface structure shown in FIGS. 1 and 2 can be formed on the surface thereof.
As such a multilayer structure, for example, a layer structure in which an oxygen barrier layer and an oxygen absorption layer are appropriately laminated on one surface of the base resin layer 1 through an adhesive resin layer, and the same kind as the resin layer 1 is used. The structure which laminated | stacked the layer of polyester resins, such as these resin and polyethylene terephthalate, can be illustrated. Such a multilayer structure is particularly applied when the structure 10 is used in the form of a container.

The oxygen barrier layer in such a multilayer structure is formed of, for example, an oxygen barrier resin such as ethylene-vinyl alcohol copolymer or polyamide. As long as the oxygen barrier property is not impaired, Other thermoplastic resins may be blended.
The oxygen absorbing layer is a layer containing an oxidizing polymer and a transition metal catalyst, as described in JP-A No. 2002-240813, etc., and the oxidizing polymer is oxygenated by the action of the transition metal catalyst. As a result, the oxygen is absorbed and the permeation of oxygen is blocked. Such an oxidizable polymer and a transition metal catalyst are described in detail in the above-mentioned JP-A No. 2002-240813, etc., and details thereof are omitted, but typical examples of the oxidizable polymer are as follows: Olefin resins having tertiary carbon atoms (eg, polypropylene, polybutene-1, etc., or copolymers thereof), thermoplastic polyesters or aliphatic polyamides; xylylene group-containing polyamide resins; ethylenically unsaturated group-containing polymers ( For example, a polymer derived from a polyene such as butadiene). Moreover, as a transition metal type catalyst, the inorganic salt, organic acid salt, or complex salt of transition metals, such as iron, cobalt, and nickel, are typical.
Further, the adhesive resin used for adhesion of each layer is known per se, for example, olefin graft-modified with carboxylic acids such as maleic acid, itaconic acid, fumaric acid or anhydrides thereof, amides, esters, etc. Resins; ethylene-acrylic acid copolymers; ion-crosslinked olefin copolymers; ethylene-vinyl acetate copolymers; and the like are used as adhesive resins.
The thickness of each layer described above may be set to an appropriate thickness according to the characteristics required for each layer.
Furthermore, it is also possible to provide as an inner layer a ligide layer obtained by blending scraps such as burrs generated when molding the multilayer structure 10 as described above with a virgin resin such as an olefin resin.

Form of structure 10;
Although the structure 10 of the present invention can have various forms, it can improve slipperiness (that is, non-adhesiveness and slipping property) particularly for viscous substances containing moisture, so that it can be used for packaging containers and lids. It is preferably used in the form of a packaging material such as a material or a cap.

In particular, as described above, in the case of the lid material, the base layer 1 is often in a form of being laminated on paper or metal foil. However, the above-described surface structure is formed on the inner surface of the lid material. This is advantageous in that it prevents adhesion of a gel-like or pudding-like product such as yogurt. Moreover, in this aspect, since the underlayer 1 absorbs the wax 3, the softening point is lowered or the thin layer 3 a of the wax 3 is formed on the underlayer 1, so that the heat sealability is improved. There is also.

Furthermore, the form of the container to which the present invention is suitably applied is not particularly limited, and may be a cup or cup shape, bottle shape, bag shape (pouch), syringe shape, acupoint shape, tray, paper plate, paper tray shape, or the like. It may have a form corresponding to the material and may be stretch-molded. Other than the form of containers, there are dishes such as spoons, forks, and lotus roots, kitchenware, and lids.

In such a container, a preformed article having the above-described underlayer 1 is formed by a method known per se, and this is applied to a film by heat sealing, vacuum forming such as plug assist molding, blow molding or the like. It is subjected to processing to form a container.
Further, as described above, depending on the form, wax that has been heated and heated by spraying or coextrusion is used by spraying or using a roller or knife coater. By applying to the inner surface of the inner surface, as described in Japanese Patent Application No. 2013-91244 (PCT / JP2014 / 61565), supplying the blow fluid together with the blow fluid from a supply pipe for the blow fluid, By co-extrusion with the resin that constitutes and supplying the inner surface to the inner surface, the surface structure shown in FIG. 1 or FIG.

FIG. 4 shows a direct blow bottle which is the most preferable form of the structure 10 of the present invention.
That is, in FIG. 4, the bottle-shaped structure indicated by 10 as a whole has a neck portion 11 provided with a thread, a trunk wall 15 connected to the neck portion 11 via a shoulder portion 13, and a lower end of the trunk wall 15. The bottle 10 has a closed bottom wall 17, and the inner surface of the bottle 10 is formed of the resin layer 1 in which the wax 3 is absorbed as described above. A distributed surface structure in which the fine particles 7 protrude from the thin layer 3a is formed.

Since such a structure 10 has a high slipperiness with respect to a moisture-containing viscous substance, in particular, a viscous content (25 ° C.) of 100 mPa · s or more, for example, ketchup, aqueous paste, honey, It is most suitable as a filling bottle for viscous contents such as various sauces, mayonnaise, mustard, dressing, jam, chocolate syrup, milky lotion, liquid detergent, shampoo, rinse and the like.

The invention is illustrated in the following examples.
In addition, the resin etc. which were used for the measurement method of various characteristics performed in the following Examples etc., a physical property, etc. and the material of a structure are as follows.

1. Measurement of sliding angle of viscous content A test piece of 30 mm x 50 mm was cut out from a multilayer structure prepared by the method described later.
Using a solid-liquid interface analysis system DropMaster700 (manufactured by Kyowa Interface Chemical Co., Ltd.) under the condition of 23 ° C.-50% RH, the test piece is fixed so that the uneven surface structure side is on top, and the content of 30 mg The object was placed on the test piece, and the angle at which the contents slipped when the test piece was gradually tilted at a rate of 1 ° / min, that is, the sliding angle was measured. The smaller the sliding angle value, the better the sliding properties of the contents. The viscous contents used are as follows.
Viscous content used; strawberry jam

2. Measurement of sliding angle of distilled water (applied experiments 1-7)
A test piece of 20 mm × 50 mm was cut out from the laminated structure produced by the method described later.
Using a solid-liquid interface analysis system DropMaster700 (manufactured by Kyowa Interface Science Co., Ltd.) under the condition of 23 ° C.-50% RH, the test piece was fixed so that the formation side of the uneven surface structure was on top, and 30 mg of distilled Water is placed on the test piece, and the test piece is placed at 1 ° / sec. The angle at which distilled water slipped when it was gradually tilted at a speed of, i.e., the sliding angle was measured. It is evaluated that the smaller the sliding angle value, the better the sliding property of the test piece.

3. Measurement of surface shape by atomic microscope A test piece of 10 mm × 10 mm was cut out from a multilayer structure prepared by the method described later.
The formation side of the uneven surface structure (hydrophobic uneven surface) was used as a measurement surface, and the surface shape of the multilayer structure was measured using an atomic force microscope (NanoScope III, manufactured by Digital Instruments). The measurement conditions are shown below.
Cantilever: Resonance frequency f ₀ = 363 to 392 kHz
Spring constant k = 20-80N / m
Measurement mode: Tapping mode Scan range: 50 μm × 50 μm
Number of scan lines: 256
From the obtained three-dimensional shape data, the surface area S in the scan range (2500 μm ² ) was determined using the software (Nanoscope: version 5.30r2) attached to the atomic force microscope, and the specific surface area r was calculated. The specific surface area r is given by the following formula (1).
r = S / S ₀ (1)
Where
S is the surface area obtained from the surface profile,
S ₀ is the scanning range area (2500 μm ² ).

4). Morphological observation of uneven surface structure by SEM A test piece of 30 mm × 50 mm was cut out from a multilayer structure prepared by the method described later.
The surface of the uneven surface structure is fixed so that the surface is facing upward, and discharge current is 20 mA, treatment time is 40 sec. Using ion sputtering (E-1045 vertical ion sputtering, manufactured by Hitachi High-Technologies). Under these conditions, the surface of the test piece was coated with a thin metal film of Pt.
Thereafter, each sample produced in Examples 1 to 3 and Comparative Examples 1 and 2 using a field emission scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies) was used to form the uneven surface structure of the test piece. Were observed at 10,000 magnifications and 100,000 magnifications to confirm the morphology of the uneven surface structure. Further, the surface of each sample prepared in the applied experiments 1 to 7 was observed at a magnification of 50000 times.

5. Cross-sectional observation of uneven surface structure by TEM A multilayer structure prepared by the method described later was frozen with an embedding resin, and a slice having a thickness of about 100 nm was cut out. The flakes were observed with a transmission electron microscope (TEM).

6). Evaluation of crystallinity of the underlayer under each heating condition (applied experiments 1-7)
A thin piece having a weight of about 3 to 5 mg was cut out from the material (film described later) used for the base resin, put into an aluminum crimp cell, and then crimped to prepare a sample for measurement. Regarding the prepared sample, the crystallinity of the base resin under each temperature condition was evaluated from the profile in the temperature rising process of the sample using a differential scanning calorimeter (Diamond DSC, manufactured by PerkinElmer). The temperature raising conditions given to various base resins are shown below.
<LDPE, HDPE, h-PP>
Temperature rise from -50 ° C to 200 ° C at 10 ° C / min <COC, EVOH, PET-G>
Temperature rise from -50 ℃ to 300 ℃ at 10 ℃ / min

Moreover, the crystallinity degree of each resin was computed from the result of the endothermic peak obtained by provision of said heat history using the following formula | equation.
Crystallinity of base resin (%) = (ΔH ₀ / ΔHm °) × 100
Where
ΔH ₀ : Heat of fusion of the base resin obtained by measurement (J / g)
ΔHm °: Heat of fusion of complete crystal of each base resin (J / g)
For the value of ΔHm ° (J / g), the following values were applied with reference to literature values.
LDPE and HDPE; ΔHm ° = 293 J / g
h−P; ΔHm ° = 207 J / g
PET; ΔHm ° = 140 J / g
Further, as comparative objects, the endothermic peak of each resin and the heat of fusion ΔH _T under the heating temperature conditions in the examples, that is, the heat of fusion of the resin at 60 ° C., 90 ° C., 120 ° C., 150 ° C., 180 ° C. ΔH ₆₀ , ΔH ₉₀ , ΔH ₁₂₀ and ΔH ₁₅₀ were calculated, and the residual crystallinity under each heating temperature condition was calculated from the values.

<Wax>
Paraffin wax Melting point: 50-52 ° C
SP value (δ1): 17.3 (MPa) ^1/2
Average molecular weight: 280

<Base resin>
A film having a thickness of about 400 μm was prepared using each material, and used as a test piece.
(However, PET was evaluated using a biaxially stretched film (thickness: 100 μm).)
Low density polyethylene (LDPE)
Melting point: 108 ° C
Crystallinity: 30%
Glass transition point (Tg): -78 ° C
SP value (δ2): 17.9 (MPa) ^1/2
Difference in SP value from paraffin wax: 0.6
High density polyethylene (HDPE)
Melting point: 132 ° C
Crystallinity: 55%
Glass transition point (Tg): -78 ° C
SP value (δ2): 18.7 (MPa) ^1/2
Difference in SP value from paraffin wax: 1.4
Homo polypropylene (h-PP)
Melting point: 164 ° C
Crystallinity: 42%
Glass transition point (Tg): about 5 ° C
SP value (δ2): 16.4 (MPa) ^1/2
Difference in SP value from paraffin wax: 0.9
Cyclic olefin copolymer (COC)
Crystallinity: Amorphous Glass transition point (Tg): 80 ° C
SP value (δ2): 13.8 (MPa) ^1/2
Difference in SP value from paraffin wax: 3.5
Ethylene vinyl alcohol copolymer (EVOH)
Melting point: 190 ° C
Glass transition point (Tg): 60 ° C
SP value (δ2): 18.9 (MPa) ^1/2
Difference in SP value from paraffin wax: 1.6
Polyethylene terephthalate (PET)
Melting point: 265 ° C
Glass transition point (Tg): 80 ° C
SP value (δ2): 22.7 (MPa) ^1/2
Difference in SP value from paraffin wax: 5.4
PET-G
Crystallinity: Amorphous Glass transition point (Tg): 80 ° C
SP value (δ2): 20.4 (MPa) ^1/2
Difference in SP value from paraffin wax: 3.1

<Roughening material fine particles>
Hydrophobic wet silica, average particle size 2.8 μm, BET specific surface area 500 m ² / g
Hydrophobic dry silica Average primary particle size 7 nm, BET specific surface area 220 m ² / g
Hydrophobic calcium carbonate (surface treatment with fatty acid)
Average primary particle size 30 nm, BET specific surface area 30 m ² / g

<Other materials>
Base material for base layer formation General base paper (basis weight 250g / m ² )
Binder resin (Comparative Example 1)
Aqueous polyethylene emulsion Composition: resin component / solvent / distilled water = 25/20/55 (weight ratio)
Resin component: melting point = 81 ° C., molecular weight = approximately 60,000

<Example 1>
As the wax, paraffin wax was used, and hydrophobic wet silica was used as the surface roughening fine particles. Also, low density polyethylene (LDPE) was used as the base resin, and the base layer (thickness 20 μm) of this polyethylene was used as a general base paper ( 250 g / m ² ), and used as a molded body for forming an uneven surface.

Paraffin wax (melting point: 50 to 52 ° C.) was supplied to a vial having a capacity of 50 ml, heated and melted at 90 ° C., and hydrophobic wet silica was added to prepare a wax composition (non-solvent coating composition). In this wax composition, the mixing ratio of wax to hydrophobic wet silica (wax: silica) is 93: 7 (weight ratio).
A wax coater (# 3) heated to about 70 ° C. with stirring this wax composition while being heated at 90 ° C. is used as an underlayer (LDPE layer having a thickness of 20 μm) on the surface of the molded body. The multilayer structure was prepared by coating.

The multilayer structure was heated in an oven at 90 ° C. for 5 minutes to maintain the molten state of the wax component contained in the coating layer of the wax composition, and then cooled at room temperature.
Table 1 shows the layer structure, the composition of the wax composition used, and the type of the base resin for the multilayer structure.
In addition, for the multilayer structure before and after oven heating, the sliding angle of the above-mentioned viscous content, the measurement of the surface shape, and the morphology observation of the uneven surface structure by SEM were performed. Table 2 shows values of the sliding angle and the specific surface area of the uneven structure.
In addition, three-dimensional images obtained by measuring the surface shape are shown in FIGS. 5 and 6, respectively. Furthermore, observation images obtained by morphological observation of the rugged surface structure by SEM are shown in FIG. 7, FIG. 8, FIG. 9, and FIG.

<Example 2>
A wax composition was prepared in the same manner as in Example 1 except that the hydrophobic dry silica described above was used in place of the hydrophobic wet silica as the roughening fine particles, and a multilayer structure was prepared in the same manner. Was made.
Table 1 shows the layer structure, the composition of the wax composition used, and the type of the base resin for this multilayer structure. Table 2 shows various measurement results before and after oven heating. Further, FIG. 11 and FIG. 12 show observation images obtained from the results of morphological observation, and FIG. 13 shows images obtained by cross-sectional observation.

<Example 3>
As roughening material fine particles, calcium carbonate is used and the composition of the wax composition is paraffin wax: hydrophobic calcium carbonate = 55: 45 (weight ratio). A multilayer structure was produced.
Table 1 shows the layer structure, the composition of the wax composition used, and the type of the base resin for this multilayer structure. Table 2 shows various measurement results before and after oven heating. Further, FIGS. 14 and 15 show observation images obtained as a result of morphological observation.

The basic layer structure of the multilayer structure manufactured in Examples 1 to 3 is as follows, with the formation surface of the hydrophobic uneven structure as the inner surface.
Non-solvent coating layer / underlying resin layer (LDPE, 20 μm) / base material layer (base paper)

<Comparative Example 1>
Put ethanol and distilled water as a dispersion medium into a 50 ml vial, and further supply hydrophobic wet silica (roughening material fine particles) and aqueous polyethylene emulsion (binder) to prepare a solvent coating composition having the following composition. did.
Resin component in ethanol / distilled water / hydrophobic silica / aqueous polyethylene emulsion = 45/45/5/5 (weight ratio)

Using the bar coater (# 3), the above solvent coating composition is applied to the surface of the base layer (LDPE, 20 μm) formed on the base material layer (base paper), and a multilayer structure having the following basic composition Was made.
Solvent coating layer / underlying resin layer (LDPE, 20 μm) / base material layer (base paper)
The prepared multilayer structure was heated using an oven at 90 ° C. for 5 minutes to melt the binder component contained in the solvent coating layer, and then cooled at room temperature.
Table 1 shows the layer structure, the composition of the solvent coating composition used, and the type of the base resin for this multilayer structure. Table 2 shows various measurement results before and after oven heating.

<Comparative example 2>
A wax composition was applied to the underlayer in the same manner as in Example 1 except that a PET film (film thickness 100 μm) was used as the underlayer, and a non-solvent coating layer (wax composition) / PET film (100 μm) A multilayer structure was created.
This multilayer structure was heated using an oven at 90 ° C. for 5 minutes to melt the wax component contained in the non-solvent coated product layer, and then the multilayer structure was cooled at room temperature.
Table 1 shows the layer structure, the composition of the non-solvent coating composition (wax composition) used, and the type of the base resin for this multilayer structure. Table 2 shows various measurement results before and after oven heating.

<Discussion>
From the results of Tables 1 and 2, the specific surface area of the multilayer structure of Example 1 is 1.10 before the heating step (FIG. 5) and 1.28 after the heating step (FIG. 6). Thus, it can be seen that the specific surface area of the multilayer structure has increased.
Regarding the sliding angle of the viscous contents, the sample before the heating process had a sliding angle value of 90 ° (not sliding), whereas the sample after the heating process had a sliding angle value of 6 °. . Therefore, it can be seen that as the specific surface area of the sample surface increases, the sliding property is greatly improved.
Examples 2 and 3 are examples in which hydrophobic dry silica and hydrophobic calcium carbonate are used as the roughening material fine particles, respectively. However, the viscous content slides down before the heating step as in Example 1. The result shows that the viscous content slides down after the heating step, whereas the state does not.

On the other hand, for Comparative Example 1, the specific surface area of the multilayer structure increased from 1.18 to 1.30 before and after the heating step, while the sliding angle of the viscous content was 90 ° both before and after the heating step. It can be seen that the sliding property is not improved regardless of the presence or absence of heating. This is presumably because the resin component used as the binder had a high molecular weight of several tens of thousands, so that it was not sufficiently diffused into the underlayer and voids were not sufficiently formed.
Furthermore, in Comparative Example 2, it can be seen that the specific surface area of the multilayer structure does not change before and after the heating step, the sliding angle of the viscous content is 90 ° both before and after the heating step, and the sliding property is not improved. From the results of surface observation, it was found that even after the heating step, a layer in which hydrophobic fine particles and wax were mixed was formed, and the shape of the hydrophobic fine particles could not be clearly confirmed.

7 and 8 show the results of observing the surface state of the sample before the heating step in Example 1, and the fine particles form a layer mixed with wax, and the uneven structure of the fine particles is completely observed. A state of smoothness was seen.
On the other hand, with respect to FIG. 9, which is the result of observing the state of the sample after the heating process in Example 1, a concavo-convex structure was formed on the surface, and it was seen that the surface structure was changed by heating. . Further, FIG. 10 shows the result of further enlarging the surface and observing, but a metabol solid layer is formed, and one spherical metaball forming this solid layer is about 100 nm. It was confirmed that it has an equivalent circle diameter.

11 and 12 show the results of observing the surface morphology of the multilayer structure after the heating process in Example 2. FIG. As in Example 1, it was observed that wax was coated around the fine particles, a metabol solid layer was formed, and the equivalent circle diameter of one metaball was about 50 nm.

FIG. 13 is a result of observing a cross section of the uneven surface structure of Example 2. In the figure, the notation: A (black) indicates hydrophobic particles, and the notation: B indicates the presence of wax. Therefore, it was confirmed that the surface uneven structure in the surface layer was formed by hydrophobic particles and wax.

14 and 15 are the results of observing the surface state of Example 3. FIG. In the same manner as in Example 1, the surface of the fine particles was covered with wax to form a metabol solid layer, and the equivalent circle diameter of the metaball was about 100 nm. Therefore, it was verified that the same uneven structure can be formed even if the fine particles are other than hydrophobic silica.

Summarizing these results, all the samples having good liquid repellency, as in Example 1, Example 2 and Example 3, have the roughening material fine particles dispersed in the wax and contain the solvent. An uneven surface structure is formed by a method in which a coating composition that has not been coated is coated and cooled on a base layer made of a resin compatible with wax and then the wax component is melted by a heating process.
Assuming the formation of the uneven surface structure in the present invention, the formed uneven surface structure is an uneven shape having a smooth curved surface, and hydrophobic fine particles having an average primary particle size of nano order are dispersed inside the unevenness. is doing. The unevenness of the formed surface has a scale of about 100 nm. This is because the force acting when the wax is coated on the surface of the fine particles, that is, in the region where the intermolecular force between the fine particles and the wax is 100 nm or less. It is speculated that the main factor is that this power is dominant only. That is, it is considered that a specific three-dimensional structure having a predetermined concavo-convex structure and having voids therein is formed by intermolecular force and absorption / diffusion into the base resin layer.

<Application experiment example>
The following experiment shows that the formation of the metaball three-dimensional layer is greatly influenced by the difference in SP value from the wax and the heating conditions for maintaining the melting of the wax.

<Experiment 1>
Paraffin wax (melting point: 50 to 52 ° C.) is supplied as a wax melt to a 50 ml capacity vial, heated and melted at 70 ° C., added with the above-described hydrophobic dry silica, and a wax composition in which fine particles are dispersed (non-coated) Solvent coating composition) was prepared.
In this wax composition, the mixing ratio of wax to hydrophobic dry silica (wax: silica) is 93: 7 (weight ratio).

A film prepared by using LDPE as a base resin (thickness: about 6) using a bar coater (# 6) heated to about 70 ° C. while the wax composition was melted and stirred under heating at 70 ° C. 400 μm) to form a multilayer structure.

This multilayer structure is heated using an oven under three conditions of 60 ° C.-5 min, 90 ° C.-5 min, and 120 ° C.-5 min to melt the wax component contained in the coating layer of the wax composition, and then at room temperature. Cooled down.
About such a multilayer structure, the above-mentioned measurement of the sliding angle of distilled water and surface observation were performed on the multilayer structure samples before and after oven heating. The obtained sliding angle value and the presence or absence of the uneven structure are shown in Table 3 together with the type of the base resin used to create the multilayer structure and its physical properties (melting point, SP value, difference in SP value from wax ΔSP). It was. Moreover, the form observation of the uneven | corrugated surface structure by SEM was also performed. The obtained observation image is shown in FIG.
In addition, using the base resin film used for the production of the multilayer structure, the crystallinity of the base layer under each heating condition was evaluated, and the change in the endothermic peak of the sample was measured. The result is shown in FIG.
Furthermore, the amount of heat of fusion ΔH _T of the resin under each heating temperature condition was determined from the results of FIG. 17 to calculate the crystallinity. The results are shown in Table 5.

<Experiment 2>
A multilayer structure was prepared in the same manner as in Experiment 1 except that an HDPE film was used as the base resin film, the same measurement was performed, and the results are shown in Table 3. Moreover, the form observation result (SEM photograph) of the uneven | corrugated surface structure was shown in FIG.
Furthermore, using the base resin film used for the production of the multilayer structure, the crystallinity of the base layer under each heating condition was evaluated, and the change in the endothermic peak of the sample was measured. The result is shown in FIG.
Furthermore, the amount of heat of fusion ΔH _T of the resin under each heating temperature condition was determined from the results of FIG. 18 to calculate the crystallinity. The results are shown in Table 5.

<Experiment 3>
A multilayer structure was prepared in the same manner as in Experiment 1, except that an h-PP film was used as the base resin film and 150 ° C.-5 min was added as the heating condition of the multilayer structure. Are shown in Table 3. Moreover, the form observation result (SEM photograph) of the uneven | corrugated surface structure was shown in FIG.
In addition, the crystallinity of the base resin layer under each heating condition was evaluated using the base resin film used for the production of the laminated structure, and the change in the endothermic peak of the sample was measured. The result is shown in FIG.
Furthermore, the amount of heat of fusion ΔH _T of the resin under each heating temperature condition was determined from the results of FIG. 18 to calculate the crystallinity. The results are shown in Table 5.

<Experiment 4>
A multilayer structure was prepared in the same manner as in Experiment 3 except that a COC film was used as the base resin film, the same measurement was performed, and the results are shown in Table 3. Moreover, the form observation result (SEM photograph) of the uneven | corrugated surface structure was shown in FIG.

<Experiment 5>
A multilayer structure was prepared in the same manner as in Experiment 4, except that EVOH was used as the material for the base resin film, and the heating condition of the laminated structure was changed to 180 ° C.-5 min except 60 ° C.-5 min. The results are shown in Table 4. Moreover, the form observation result (SEM photograph) of the uneven | corrugated surface structure was shown in FIG.

<Experiment 6>
A multilayer structure was prepared in the same manner as in Experiment 4 except that a PET film was used as the base resin film, and the sliding angle of distilled water was measured. The results are shown in Table 4.

<Experiment 7>
A multilayer structure was prepared in the same manner as in Experiment 4 except that a PET-G film was used as the base resin film, and the same measurement was performed. The results are shown in Table 4. Moreover, the form observation result (SEM photograph) of the uneven | corrugated surface structure was shown in FIG.

From the results of Tables 3 and 4, when LDPE was used as the base resin, the sliding angle was 22 ° under the condition of 60 ° C.-5 min, and good liquid repellency was not obtained. Next, when heated at 90 ° C. for 5 minutes, the sliding angle was 1 °, and very good liquid repellency was obtained.
However, when the temperature was further raised and heating was performed under the condition of 120-5 min, the sliding angle increased significantly, and the liquid repellency tended to be lost.

Moreover, from FIG. 17 (experiment 1) showing the crystallinity evaluation of the underlayer under each heating condition, since an endothermic peak starts to appear at about 30 ° C. for LDPE, melting of the crystal portion starts from about 30 ° C. In addition, it is shown that the amorphous portion gradually increases as the temperature rises. Thereafter, since the peak reaches a peak at 109 ° C., the melting point is reached at 109 ° C., and it can be evaluated that the crystal part is completely melted and amorphous in a temperature range higher than that.
Comparing the endothermic peak of this LDPE, the heating temperature in Experiment 1 (60 ° C., 90 ° C., 120 ° C.), the crystallinity under each temperature condition (ΔH ₆₀ , ΔH ₉₀ , ΔH ₁₂₀ ) and the results of surface observation When the test piece was heated at 60 ° C., that is, when the resin crystallinity was almost unchanged (ΔH ₆₀ ≈ΔH ₀ ), the surface state tended not to change.
In addition, when the test piece when heated at 90 ° C., that is, in a state where the crystal part of the resin is melted to some extent (ΔH ₉₀ <ΔH ₀ ), the surface structure tends to change and a metaball-like structure tends to be formed. It was seen.
Furthermore, when the test piece was heated at 120 ° C., that is, in the state where all of the crystal part of the resin was melted (ΔH ₁₂₀ = 0), there was a tendency that the uneven structure was not formed.

Also, from FIG. 18 (experiment 2) showing the evaluation of the crystallinity of the underlayer under each heating condition, since an endothermic peak begins to appear at about 105 ° C. for HDPE, the melting of the crystal portion starts at about 105 ° C. It has been shown that the amorphous portion gradually increases with increasing temperature. Thereafter, since the peak reaches the peak at 131 ° C., it can be evaluated that 131 ° C. is the melting point, and in the temperature region higher than that, all the crystal parts are melted and are in an amorphous state.
Comparing the endothermic peak of this HDPE, the heating temperature in Experiment 2 (60 ° C., 90 ° C., 120 ° C., 150 ° C.) and the crystallinity (ΔH ₆₀ , ΔH ₉₀ , ΔH ₁₂₀ , ΔH ₁₅₀ ) under each temperature condition When the test piece was heated at 60 ° C., that is, when the resin crystallinity was not changed (ΔH ₆₀ ≈ΔH ₀ ), the surface state tended not to change.
In addition, the test piece when heated at 90 ° C. is in a state where the resin crystallinity is not changed (ΔH ₉₀ ≈ΔH ₀ ), and the surface structure does not change, and there is a tendency that the uneven structure is not formed. It was.
On the other hand, when the test piece when heated at 120 ° C., that is, in a state where the resin crystal part is melted to some extent (ΔH ₁₂₀ <ΔH ₀ ), the surface structure tends to change and a metaball-like structure tends to be formed. It was.
However, when the test piece was heated at 150 ° C., that is, in a state where all the crystal parts of the resin were melted (ΔH ₁₅₀ = 0), the uneven structure tended to be not formed.
Further, from FIG. 19 (experiment 3) showing the crystallinity evaluation of the underlayer under each heating condition, since the endothermic peak starts to appear at about 110 ° C. for h-PP, the melting of the crystal portion starts at about 110 ° C. It has been shown that the amorphous portion gradually increases with increasing temperature. Thereafter, since the peak reaches the peak at 164 ° C., 164 ° C. is the melting point, and it can be evaluated that the crystalline portion is completely melted and amorphous in a temperature range higher than that.

The endothermic peak of h-PP, the heating temperature in Experiment 3 (60 ° C., 90 ° C., 120 ° C., 150 ° C.) and the crystallinity under each temperature condition (ΔH ₆₀ , ΔH ₉₀ , ΔH ₁₂₀ , ΔH ₁₅₀ ) In comparison, when the test piece was heated at 60 ° C., that is, when the resin crystallinity was not changed (ΔH ₆₀ ≈ΔH ₀ ), the surface state tended not to change.
Further, the test piece when heated at 90 ° C. was in a state where the crystallinity of the resin was not changed (ΔH ₉₀ ≈ΔH ₀ ), and a tendency that the surface structure did not change was observed.
Further, the test piece when heated at 120 ° C. was in a state where the crystallinity of the resin was not changed (ΔH ₁₂₀ ≈ΔH ₀ ), and a tendency that the surface structure did not change was observed.
Compared with these, when the test piece is heated at 150 ° C., that is, when all of the crystal part of the resin is melted (ΔH ₁₅₀ <H ₀ ), the surface structure changes and a metaball-like structure is formed. The tendency was seen.

From these results, as a condition for obtaining good liquid repellency,
(A) The SP value of paraffin wax as a dispersion medium is close to the SP value of the base resin.
That is, when δ1-δ2 is 1.5 or less,
(B) When heating the laminated structure after coating, when the crystal of the base resin is melted to some extent and the crystal part remains (0 <ΔH _T <ΔH ₀ ),
That is, as a condition for creating the above state, the melting point of the resin is X ° C.
X-5 ≧ Y ≧ X-50
When heated for 5-10 minutes at a temperature Y satisfying
(C) The case where the base resin is a crystalline resin can be mentioned, and when all of these conditions are satisfied, a tendency to form a metaball-shaped uneven structure was observed.

<Discussion>
With regard to the concavo-convex structure of the metaball shape obtained under these conditions, the concavo-convex structure is a three-dimensionally stacked structure and has a large amount of fine voids. It is considered that a particularly high liquid repellency is expressed.
The reason why such a structure is formed is that when the multilayer structure is heated, the paraffin wax used as a dispersion medium diffuses into the base resin and is absorbed. it is conceivable that. When the compatibility between the paraffin wax and the base resin is low, that is, when the difference between δ1 and δ2 is large, the diffusion itself into the base resin does not occur, or the diffusion speed is very slow, so the wax existing on the outermost surface It is considered that a metaball-shaped structure is difficult to form because the components are not reduced and the surface is kept smooth.
Further, when heating the laminated structure after coating, under the condition that the crystal part of the base resin is not melted at all (ΔH ₀ ≈ΔH _T ), the crystal part of the base resin suppresses the diffusion of paraffin wax, and the base resin It is thought to have a function to prevent absorption into the layer. As a result, it is considered that the outermost wax component does not decrease, the surface is kept smooth, and a metaball-shaped structure is hardly formed.

On the other hand, when heated under the melting condition (ΔH = 0) where the base resin is completely melted, that is, the melting point of the base resin or higher, it is considered that the crystal part is completely melted and the paraffin wax is diffused well. At the same time, since the base resin itself melts and becomes liquid, it is considered that the wax structure and the hydrophobic fine particles themselves are drawn into the base resin layer. As a result, it is considered that a metaball-shaped uneven structure is difficult to form.
When the base resin is an amorphous resin (COC, PET-G), it is presumed that the same phenomenon as in the state where the crystal part is completely melted is generated, and it is considered that the uneven structure was not formed.

Therefore, in the present invention, a combination of a base resin and a wax having good compatibility with each other is selected, and coating is performed on the surface in a state where fine particles are dispersed in the wax, and the crystal portion of the base resin is sufficiently melted. Further, by heating the multilayer structure under the condition that the crystal part remains, it is presumed that a metaball-shaped structure is rapidly formed on the surface by the wax component being absorbed into the base resin.

1: Underlying resin layer in which paraffin wax is absorbed (underlying layer)
3: Paraffin wax 5: Three-dimensional layer of metaball 7: Fine particles 10: Structure

Claims (15)

1. In a structure including a molded body whose surface is formed of a resin layer, and fine particles distributed on the resin layer on the surface of the molded body,
   A structure in which wax is distributed along with fine particles on the surface of the resin layer, and a part of the wax is absorbed in the resin layer.
2. The structure according to claim 1, wherein the fine particles are hydrophobic fine particles.
3. The structure according to claim 1, wherein a metaball three-dimensional layer in which the wax is continuous in a metaball shape is formed on the resin layer, and the fine particles are distributed inside the metaball three-dimensional layer.
4. The structure according to claim 3, wherein the three-dimensional metaball layer has a connecting structure of balls having a diameter of 20 to 200 nm as observed with a scanning electron microscope.
5. The structure according to claim 1, wherein the fine particles have an average primary particle diameter of 4 nm to 1 µm.
6. The structure according to claim 1, wherein the melting point of the wax is in the range of 40 ° C to 110 ° C.
7. The structure according to claim 1, wherein the resin forming the resin layer has an SP value difference of 1.5 (MPa) ^1/2 or less from the wax.
8. The structure according to claim 7, wherein the resin forming the resin layer is an acyclic olefin resin, and the wax is at least one of paraffin wax, microcrystalline wax, or polyethylene wax.
9. The structure according to claim 1, wherein the molded body has a form of a container, and the fine particles and the wax are distributed on the inner surface on the side in contact with the contents contained in the container.
10. The structure according to claim 9, wherein the container is a bottle made of olefin resin.
11. The molded body has a form of a lid material applied to the container mouth by heat sealing, and the fine particles and the wax are distributed on the surface in contact with the contents accommodated in the container. The structure according to claim 1.
12. A step of preparing a non-solvent coating composition containing fine particles and molten wax, and a molded body having a surface formed of a layer of a wax-absorbing resin;
    A coating step of coating the non-solvent coating composition on the surface of the molded body;
    Next, the surface of the molded body is heated to a temperature equal to or higher than the melting point of the wax to maintain the state in which the wax is melted, whereby the wax-absorbing resin layer on the surface absorbs the wax.
    and,
    A cooling step of solidifying the molten wax by cooling the surface of the molded body after the wax absorption step;
    A method for producing a structure having a hydrophobic surface, comprising:
13. The manufacturing method according to claim 12, wherein the wax-absorbing resin has an SP value difference of 1.5 (MPa) ^1/2 or less from the wax.
14. In the wax absorption step, when the melting point of the wax-absorbing resin is X ° C., heating for maintaining the wax in a molten state is performed by the following conditional expression
    X-5 ≧ Y ≧ X-50
    The method according to claim 12, which is carried out at a temperature Y satisfying the following conditions for 5 seconds to 10 minutes.
15. When producing a molded body having a surface formed of the wax-absorbing resin layer by extrusion molding using the wax-absorbing resin, at a position adjacent to the wax-absorbing resin layer and on the surface side, A method for producing a structure having a hydrophobic surface, comprising coextruding a non-solvent composition containing fine particles and a molten wax.

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