JP6307129B2 - Structure having a gel-like coating on the surface - Google Patents

Description

  The present invention relates to a structure having a gel-like coating on the surface, and particularly relates to a structure suitably used as a container.

  In a container in which a liquid content is stored, dischargeability to the content is required regardless of the material of the container. In the case of containing a low viscosity liquid such as water, such discharge is hardly a problem. For example, in the case of a viscous material such as mayonnaise or ketchup, it may be a plastic container but glass. Whether it is a made container, this discharge is a serious problem. That is, such contents are not quickly discharged by tilting the container, and adhere to the container wall, and thus cannot be used up to the end. Especially, a considerable amount of contents are placed at the bottom of the container. Remains without being discharged.

Recently, various techniques for improving slipperiness with respect to viscous substances by forming an oil film on the surface of a molded body such as a container have been proposed (for example, Patent Documents 1 and 2).
According to such a technique, the slipperiness can be drastically improved as compared with the case where an additive such as a lubricant is added to the synthetic resin forming the surface of the molded body, and thus is currently attracting attention.

  However, in the means for modifying the surface properties by forming an oil film on the surface of the base as described above, the effective life of the slipperiness exhibited by the oil film is short, and the slipperiness decreases after a long period of time. In some cases, however, problems such as the contents sticking to the surface have occurred. This tendency is particularly noticeable when the material that slides down the surface is an emulsion, particularly a mayonnaise-like food with low oil content.

For example, the present applicant has previously described a packaging container containing an oil-in-water emulsion typified by mayonnaise-like food, and an oil film is formed on the inner surface of the container in contact with the oil-in-water emulsion. A packaging container has been proposed (Japanese Patent Application No. 2014-023425).
In addition, the present applicant has also disclosed a packaging material characterized in that a liquid film is formed on the inner surface in contact with the contents, and solid particles having a particle diameter of 300 μm or less are dispersed in the liquid film. (Japanese Patent Application No. 2014-126877).
However, even in these techniques previously proposed by the present applicant, the problem of a decrease in slipperiness over time has not been effectively solved.

WO2012 / 100099 WO2013 / 022467

Accordingly, an object of the present invention is to provide a structure in which a lubricity coating for improving slipperiness such as slipperiness is formed and the effect of improving the slipperiness is sustained and stably exhibited. There is.
Another object of the present invention is to provide a structure that is particularly used as a container in which an emulsion is accommodated as a content and has excellent slidability with respect to the emulsion.

  The inventors of the present invention have conducted many experiments on the slipperiness with respect to viscous substances, and as a result of studying them, by mixing fine fixed particles in an oily liquid and forming a gel-like coating on the surface, The inventors have found that the slipperiness of various viscous substances, particularly emulsions, is high, and that the slipperiness can be stably exhibited over a long period of time, thereby completing the present invention.

According to the present invention, there is provided a structure in which a gel-like coating is formed on the surface of a thermoplastic resin substrate molded into a predetermined shape, the gel-like coating containing fine solid particles and rotating. A structure having a viscosity of 35 to 250 mPa · s (25 ° C.) measured at several 20 rpm is provided.

In the structure of the present invention,
(1) The gel-like coating has a viscosity (25 ° C.) of 100 mPa · s or less,
(2) the thermoplastic resin substrate is a container, and the gel-like coating is formed on the inner surface of the container;
Is preferred.

Since the structure of the present invention is provided with a gel-like coating containing fine solid particles on the surface, it exhibits not only excellent slipperiness (initial slipperiness) against various viscous substances , but also its aging over time. The decrease is effectively avoided and the slipperiness is excellent. Such excellent initial slipperiness and sustainability of slipperiness are effectively exhibited even for viscous emulsions such as mayonnaise-like foods.

For example, in the structure in which the thermoplastic resin substrate is a container, a predetermined gel-like coating is formed on the inner surface of the container ( thermoplastic resin substrate) according to the present invention. As shown in the above, when the mayonnaise-like food is filled into this structure, even after storage at 40 ° C. for 2 months, the same activity (sliding property) as that immediately after filling is exhibited.
On the other hand, when the oil film is not formed on the inner surface of the container (base material) only with the oily liquid used for forming the gel-like coating, the contents (mayonnaise) are stored at 40 ° C. for 2 weeks. The slipperiness for food-like foods has declined significantly.

As described above, it has been confirmed as a phenomenon by a lot of experiments that excellent initial slipping property and sustainability of slipping property can be obtained by forming a gel-like coating on the surface according to the present invention. Although the reason is not clearly clarified, the present inventors presume as follows.
That is, when slipperiness is enhanced by a simple oil film, the oil film is gradually scraped off from the surface by the viscous water-containing substance passing through the oil film. Therefore, in the initial stage, the slipperiness due to the oil film is effectively expressed, but as the viscous water-containing substance flows on the oil film, the oil film is consumed, and as a result, the slipperiness gradually decreases. , Its sustainability will be unsatisfactory.
However, in the present invention, since the gel-like coating is formed on the surface of the substrate, when the viscous water-containing material flows on the gel-like coating, the contact with the viscous water-containing material is caused by the stress (load). Oily liquid is liberated at the interface and exhibits excellent slipperiness. At the same time, the interface between the gel-like coating and the surface of the molded body is hardly subjected to stress (load), does not move from the surface of the molded body, and is stably held. to continue. That is, even when a viscous water-containing substance repeatedly flows on the gel-like coating, the gel-like coating is hardly consumed. As a result, it is considered that not only the initial slip property is excellent, but also the excellent sustainability of the slip property can be obtained.

Since the structure of the present invention exhibits excellent slipperiness with respect to viscous substances and is also excellent in its sustainability, it has a viscosity (25 ° C.) such as mayonnaise, ketchup and various dressings. It is particularly preferably used as a container for storing a material of 1260 mPa · s or more.

The schematic sectional side view for demonstrating the surface form 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.

  With reference to FIG. 1, the structure of this invention consists of the base material 1 shape | molded by the shape according to a use, and the gel-like coating | cover 3 formed in the surface.

<Substrate 1>
The base material 1 is formed of a thermoplastic resin capable of holding the gel-like coating 3 on the surface thereof , and may have a form corresponding to the application.
In particular, from the viewpoint that the structure of the present invention exhibits excellent slipperiness with respect to the viscous water-containing substance due to the gel-like coating 3, the base material 1 is a pipe for flowing such a water-containing substance, It is preferable that the container has a form such as a container or a container lid for accommodating it, and the gel-like coating 3 is formed on the surface in contact with such a water-containing substance.

In the present invention, from the viewpoint of holding the gel-like coating 3, the surface of the substrate 1 (the ground surface of the gel-like coating 3) is formed of a thermoplastic resin.

Such thermoplastic resin (hereinafter, referred to as base resin), the formed shape is easy and high affinity for the oily liquid of the gel coating 3, a gel-like coating 3 containing such oil liquid From the viewpoint of more stable holding, for example, the following can be exemplified.
Olefin resins such as low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene or α-olefins such as ethylene, propylene, 1-butene and 4-methyl-1-pentene Random or block copolymers, cyclic olefin copolymers, etc .;
Ethylene / vinyl copolymers, such as ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, ethylene / vinyl chloride copolymer, etc .;
Styrenic resin such as polystyrene, acrylonitrile / styrene copolymer, ABS, α-methylstyrene / styrene copolymer, etc .;
Vinyl resins such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride / vinylidene chloride copolymers, polymethyl acrylate, polymethyl methacrylate, etc .;
Polyamide resin, for example, nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, etc .;
Polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and copolyesters thereof;
Polycarbonate resin;
Polyphenylene oxide resin;
Biodegradable resins, such as polylactic acid;
Of course, as long as the moldability is not impaired, a blend of these thermoplastic resins can also be used as the base resin.

In the present invention, among the thermoplastic resins described above, olefin resins and polyester resins used as container materials for storing viscous contents are suitable, and olefin resins are optimal.
That is, since the olefin resin has a lower glass transition point (Tg) and higher molecular mobility at room temperature than a polyester resin such as PET, a part of the oily liquid forming the gel-like coating 3 is used. It is optimal in that it penetrates into the interior and thereby keeps the gel-like coating 3 stably on the surface.
Furthermore, the olefin-based resin is highly flexible and is also used for the application of a squeeze bottle (squeeze bottle) by direct blow molding described later, from the viewpoint of applying the structure of the present invention to such a container. Also olefin resins are suitable.

  In addition, the base material 1 may have a single layer structure of the thermoplastic resin as described above, or may be a laminate of the thermoplastic resin and paper, and a plurality of thermoplastic resins. May have a multi-layer structure in which are combined.

  Since the structure of the present invention is excellent in slipperiness and persistence for viscous water-containing materials, it is effectively applied to applications where such water-containing materials flow in contact with the gel-like coating 3. It is most suitable that it is used as a container in which a water-containing substance is accommodated, that is, the base material 1 has the form of a container in that the advantages of the present invention can be enjoyed to the maximum.

  In particular, in the case where the substrate 1 has the form of a container, when the inner surface is formed of an olefin resin or a polyester resin, an oxygen barrier layer or an oxygen is appropriately interposed as an intermediate layer through an adhesive resin layer. It is possible to adopt a structure in which an absorption layer is laminated and a resin of the same type as a base resin (olefin resin or polyester resin) that forms the inner surface is laminated on the outer surface side.

The oxygen barrier layer in such a multilayer structure is formed of an oxygen barrier resin such as an ethylene-vinyl alcohol copolymer or polyamide, for example, 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, 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-2002-240813 and the like. 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.

Adhesive resins used for bonding the layers are known per se, for example, olefin resins graft-modified with carboxylic acids such as maleic acid, itaconic acid, fumaric acid or their anhydrides, amides, esters, etc .; An ethylene-acrylic acid copolymer; an ion-crosslinked olefin copolymer; an ethylene-vinyl acetate copolymer; and the like are used as the adhesive resin.
The thickness of each layer described above may be set to an appropriate thickness according to the characteristics required for each layer.

  Further, it is possible to provide a ligide layer in which scraps such as burrs generated when the substrate 1 having the multilayer structure as described above is blended with a virgin resin such as an olefin resin as an inner layer. Of course, it is also possible to use as the base material 1 a container having an inner surface formed of a polyester resin or a polyester resin and an outer surface formed of a polyester resin or an olefin resin.

  The shape of the container used as the substrate 1 is not particularly limited, and has a shape corresponding to the container material, such as a cup or cup shape, a bottle shape, a bag shape (pouch), a syringe shape, an acupoint shape, or a tray shape. Alternatively, it may be stretch-molded or molded by a method known per se.

FIG. 2 shows a direct blow bottle which is the most preferable form of the substrate 1 of the present invention.
In FIG. 2, a bottle 10 indicated as a whole has a neck 11 provided with a thread, a trunk wall 15 connected to the neck 11 via a shoulder 13, and a bottom wall 17 closing the lower end of the trunk wall 15. The gel-like coating 3 is formed on the inner surface of such a bottle (base material 1).
Such a bottle 10 is preferably used for containing a viscous substance, and squeezes the body wall 15 to discharge the viscous substance contained therein. If the gel-like coating 3 is formed and the slipperiness and the sustainability of the contents are improved, such contents can be discharged quickly, and the entire amount is discharged. It is also possible to use up everything.

<Gel-like coating 3>
In the present invention, the gel-like coating 3 provided on the surface of the substrate 1 as described above is formed from an oily liquid and fine solid particles. The gel coating 3 preferably has thixotropic properties.

The oily liquid used for the formation of the gel-like coating 3 exhibits slipperiness with respect to the water-containing substance and functions as a lubricant.
Such an oily liquid must naturally be a non-volatile liquid having a low vapor pressure under atmospheric pressure, for example, a high boiling point liquid having a boiling point of 200 ° C. or higher. This is because when a volatile liquid is used, it easily evaporates and disappears with time, and it becomes difficult to form the gel-like coating 3.

  Further, from the viewpoint of being a high boiling liquid as described above, exhibiting high wettability with respect to the surface of the base material 1, and forming a gel-like coating 3 that adheres uniformly on this surface, It is preferable that the contact angle (20 ° C.) with respect to the surface is 45 ° or less and the viscosity (25 ° C.) is 100 mPa · s or less. That is, whether the surface material of the substrate 1 is made of synthetic resin, glass, or metal, the gel-like coating 3 may be formed using an oily liquid that satisfies the above physical properties.

Furthermore, among the oily liquids satisfying the physical properties as described above, the lubricating effect is higher as the surface tension is significantly different from the material to be slidable (for example, the container contents in a container). Is suitable.
That is, it is preferable to use an oily liquid having a surface tension in the range of 10 to 40 mN / m, particularly 16 to 35 mN / m in terms of improving the slipperiness with respect to the viscous water-containing substance. Typical examples include liquid paraffin, synthetic paraffin, fluorinated liquid, fluorinated surfactant, silicone oil, fatty acid triglyceride, and various vegetable oils. In particular, when the substance to be slidable is food (for example, mayonnaise or ketchup), edible oil is suitable.
Specific examples of such edible oils include soybean oil, rapeseed oil, olive oil, rice oil, corn oil, ben flower oil, sesame oil, palm oil, castor oil, avocado oil, coconut oil, almond oil, walnut oil, and bean oil. And salad oil.

The fine solid particles used in combination with the above-mentioned oily liquid impart thixotropic properties to the oily liquid, and the particle diameter must be 50 μm or less, particularly 30 μm or less. is there. That is, the solid particles form a network structure in an oily liquid, and in order to give a gel that exhibits thixotropic properties or a structure close to a gel, the solid particles are fine as described above. It must have a particle size. This is because when the particle diameter is large, a network structure in which the particles are connected cannot be formed.
The above particle diameter can be measured by, for example, a laser diffraction scattering method or microscope observation, and means a so-called secondary particle diameter (aggregated particle diameter).

In the present invention, such fine solid particles can be uniformly dispersed in an oily liquid to form a gel-like coating 3 having thixotropy, and remain solid under use and storage environments. As long as it has a melting point to be obtained, it may be formed of various organic materials and inorganic materials, but from the viewpoint of good compatibility with oily liquids, from inorganic particles such as metal particles and metal oxides Are preferably organic particles, for example, olefin wax, rice wax, carnauba wax, various celluloses, organic resin cured products (for example, cured products obtained by curing polyfunctional acrylic monomers), and the like. Rice wax is the most suitable because it can be used for foods without any restrictions.

  The gel-like coating 3 using the oily liquid and the fine solid particles described above is prepared by mixing both and stirring under strong shear. That is, strong stirring may be performed so that a network structure of fine solid particles is formed.

Gel coat 3 obtained in this way, using a rotary viscometer, the viscosity was measured at a rotational speed of 20 rpm, 25 ° C. is preferably a 35~250mPa · S. If it is less than 35 mPa · S, it will be difficult to hold in the molded body 1 for a long time, and the slipperiness with time will be low. If it is greater than 250 mPa · S, the sliding speed will be slow, and the performance may not be fully exhibited.
Further, for example, the gel-like coating 3 prepared by mixing and stirring 5 parts by mass of fine solid particles with 100 parts by mass of the oily liquid has a viscosity of 124 mPa · S at a rotation speed of 20 rpm and at a rotation speed of 2 rpm. In addition, the viscosity is 243 mPa · S, and it has a thixotropic property that the viscosity is smaller as the rotational speed is larger. Thus, by having thixotropy, the initial slip property can be increased and the sustainability can be greatly improved. For example, if the thixotropy is small (the difference in viscosity is small), the amount of oil that oozes out on the surface when the water-containing substance flows on the gel-like coating 3 tends to be low, and the initial slipping property tends to be low. The gel-like coating 3 on one surface is not stably maintained, and each time a substance flows on the gel-like coating 3, the slipperiness tends to decrease, and the durability of the slipperiness may be unsatisfactory. There is.

  In order to form the gel-like coating 3 having a viscosity in the above-described range, the above-described stirring temperature, shear rate, stirring time, and the like may be appropriately adjusted. Usually, however, per 100 parts by mass of fine solid particles. The oily liquid is preferably mixed in an amount of about 0.5 to 10 parts by mass, particularly about 1 to 10 parts by mass. Thereby, the target gel-like film 3 can be prepared with stirring at an appropriate shear rate and with an appropriate stirring time.

  The gel-like coating 3 can be formed by using various means according to the surface shape of the substrate 1. However, since the gel-like coating 3 has thixotropic properties, spray spraying is possible. Therefore, it is desirable to form the gel-like coating 3 by spraying on the surface of the predetermined substrate 1 by spraying.

The gel-like coating 3 thus formed is desirably formed on the surface of the substrate 1 in an amount of 1.00 to 3.70 mg / cm ² . That is, if this amount is too small, the slipperiness and sustainability of the gel-like coating 3 will be unsatisfactory, and even if it is formed more than necessary, no further slipperiness or sustainability will be obtained, and the cost will increase. Rather, the gel-like coating 3 tends to fall off from the surface of the substrate 1 due to its weight.

  Since the structure of the present invention described above exhibits excellent slipperiness and persistence with respect to a viscous water-containing substance, in particular, it contains a viscous water-containing substance having a viscosity (25 ° C.) of 100 mPa · s or more. Suitable for use as a container, especially a direct blow container, such as mayonnaise, ketchup, aqueous paste, honey, various sauces, mustard, dressing, jam, chocolate syrup, milky lotion, liquid detergent, shampoo, rinse, etc. Most suitable as a filling bottle for viscous contents.

The present invention will be described in the following experimental examples.
The container, gel-like film, and contents used in each example and comparative example are as follows.

<Container>
A multilayer direct blow bottle having a multilayer structure having the following layer structure and having an internal capacity of 400 g was provided.
Inner layer: Low density polyethylene resin (LDPE)
Intermediate layer: ethylene-vinyl alcohol copolymer (EVOH)
Outer layer: Low density polyethylene resin (LDPE)
Adhesive layer (between inner and outer layers and intermediate layer): acid-modified polyolefin

<Gel-like film>
Oily liquid: medium chain fatty acid added salad oil
Viscosity: 33 mPa · s (25 ° C)
Contact angle (20 ° C.): 18 degrees Solid particles: Carnauba wax Using a homogenizer, the above solid particles are finely dispersed in the above oily liquid in the amount ratio shown in Table 1 at room temperature (25 ° C.). A coating solution was prepared, and the coating amount shown in Table 1 was applied uniformly on the inner surface of the container using an air spray to form a gel film.

<Various measurement methods>
Contact angle;
10 mg of the oily liquid used for the gel-like film was dropped with the inner surface of the container as the upper surface, and measurement was performed with a contact angle meter (Kyowa Interface Science Co., Ltd. DropMaster 700) at 20 ° C. and 50% RH.
viscosity;
The viscosity was measured by putting the spindle and guard of a B-type digital viscometer into the measurement substance placed in a beaker and rotating the spindle at 25 ° C. and a rotation speed of 20 rpm for 1 minute.

<Contents>
After mixing 1 egg (50 g), 15 cc of vinegar and 2.5 cc of salt, 150 cc of cooking oil was further mixed to prepare an mayonnaise-like food for experiment. In each of the examples and comparative examples, a necessary amount of contents were prepared and used.

The evaluation method of slipperiness using the contents of each example and each comparative example is as follows.
<Slippery evaluation>
A spray nozzle was inserted into the bottle to the bottom, and the gel-like film was pulled up while spraying to apply to the entire side wall from the bottom of the bottle. In a bottle with a gel-like film formed on the inner surface of this container, 400 g of mayonnaise-like food, which is the contents, is filled in a conventional manner, the bottle mouth is heat sealed with aluminum foil, and sealed with a cap to fill the filled bottle. Obtained.
The filled bottle filled with the contents was stored at 23 ° C. for 1 week (initial bottle).
About the bottle stored by each storage period and temperature shown in Table 1, after pushing the trunk | drum and squeezing out the contents to the last through a bottle mouth part, air was put in this bottle and the shape was restored.
Next, the degree of slipping of the contents of the bottle barrel wall after the bottle is inverted (mouthed downward) and stored for 1 hour (the degree to which no contents adhere to the barrel wall) is measured. The content adhesion rate was calculated by the following formula.
Content adhesion rate (%)
= (Surface area to which the contents are attached / bottle body wall surface area) × 100
From the content adhesion rate calculated above, the slipperiness was evaluated according to the following criteria.
○: Content adhesion rate is less than 10% Δ: Content adhesion rate is 10% or more and less than 50% ×: Content adhesion rate is 50% or more <Measurement of solid particle size>
The prepared gel-like film was observed with a microscope, image-processed, and the particle size was measured. The maximum particle size was taken as the particle size of the gel film.

[Examples 1-7]
The gel-like film was applied to the molded bottle with the application amount shown in Table 1, and the slip property was evaluated.
[Comparative Example 1]
The oily liquid similar to the gel-like film was applied to the molded bottle with the application amount shown in Table 1, and the slipperiness was evaluated.
[Comparative Example 2]
The liquid which mixed the oil-like liquid similar to a gel-like coating | cover and the solid particle (particle diameter of 85 micrometers) was apply | coated to the shape | molded bottle with the application quantity in Table 1, and slipperiness was evaluated. The prepared liquid was not a gel because the solid particles were not fine solid particles.

  As a result, by forming a gel-like film on the inner surface of the bottle, the slipperiness of the contents is improved, and the slipperiness is maintained even after long-term storage at a high temperature. It was confirmed that the formed molded article was excellent in slipping of the contents and maintained the performance for a long time. Further, simply mixing the oily liquid and the solid particles in the gel film resulted in a decrease in slipperiness over time, and the same result as in the case without the solid particles was obtained. From this, it was confirmed that it is important that the solid particles become fine solid particles and become a gel.

1: Base material 3: Gel-like coating

Claims (2)

A structure in which a gel-like coating is formed on the surface of a thermoplastic resin substrate molded into a predetermined shape, and the gel-like coating contains fine solid particles and is measured at a rotational speed of 20 rpm. A structure having a viscosity of 35 to 250 mPa · s (25 ° C.). The structure according to claim 1, wherein the thermoplastic resin substrate is a container, and the gel-like coating is formed on an inner surface of the container.