JP7694137B2 - Propylene-based resin composition - Google Patents

Description

The present invention relates to a propylene-based resin composition, and more specifically, to a propylene-based resin composition containing a lubricating liquid.

Plastic containers are widely used for a variety of purposes because they are easy to mold and can be manufactured at low cost. For example, olefin resins such as polyethylene and polypropylene are ideal for molding bottles for storing viscous slurry or paste-like contents such as ketchup.

In containers such as bottles that contain viscous contents, in order to expel the contents quickly or to use them completely without leaving any residue inside the container, it is desirable for the viscous contents to fall quickly without adhering to the inside of the container when the container is turned upside down.

In order to satisfy such requirements, a method has been used in the past, as described in Patent Document 1, in which a solid lubricant such as an aliphatic amide is blended into the resin that forms the inner surface of the container, and the lubricant is allowed to bleed onto the inner surface of the container, improving the sliding properties of the contents of the container.

However, recently, attention has been focused on a method of forming a layer of a liquid different from the contents on the inner surface that comes into contact with the contents, as described in Patent Document 2. In this method, by forming a liquid layer of a liquid that is immiscible with the contents on the inner surface of the container, it is possible to significantly improve the slipperiness of the contents compared to conventionally known methods, and by turning the container upside down or tilting it, it is possible to quickly discharge the contents out of the container without them adhering to or remaining on the inner wall of the container.
This method of modifying surface properties such as slipperiness by forming a liquid layer on the surface is not limited to applications in the form of containers, but can also be applied to molded articles in the form of films, etc., and by appropriately selecting the type of liquid, the surface properties can be significantly modified.

However, as described above, in the method of modifying the surface characteristics by forming a liquid layer on the surface of a molded body such as a container, after molding the container, a liquid other than the contents is applied to the inner surface of the container by immersion, spraying, etc. to form a liquid layer. In this case, a special processing step is required to form the liquid layer, which is problematic in terms of productivity. For this reason, in order to form a liquid layer on the surface, it is industrially advantageous to mix the liquid that forms the liquid layer with the resin that forms the inner surface, perform molding using a resin composition in which such a liquid is mixed, and form a liquid layer on the surface of the molded body by bleeding the liquid after molding. In other words, even without special processing after molding, the liquid contained in the resin composition segregates on the inner surface of the container, and as a result, a liquid layer is automatically formed on the surface.

When molding a container using a resin composition containing the above liquid (hereinafter sometimes referred to as lubricating liquid), a pellet-shaped resin composition containing the lubricating liquid blended with the molding resin is used industrially. In other words, if the lubricating liquid and the molding resin are mixed to prepare the resin composition each time during molding, it is inefficient and a tank that can hold a large amount of lubricating liquid is required. Therefore, a pellet-shaped resin composition containing a high concentration of the lubricating liquid is prepared in advance, and the lubricating liquid is handled in the form of this resin composition for storage, transportation, etc., and during molding, the resin composition is diluted with the molding resin to prepare a surface-forming resin composition, which is then molded into a container, etc.

The problem is the bleeding of the lubricating liquid from the resin composition. That is, when the concentration of the liquid contained in the resin composition is low (for example, 5% by mass or less), there is no problem, but when the liquid concentration of the resin composition is high, the liquid bleeds out of the resin composition, making the pellets sticky and difficult to handle, and when the resin composition for molding is prepared by diluting the resin, the liquid concentration becomes lower than the target value due to the bleeding of the liquid. This tendency is noticeable when the molding resin mixed with the liquid is an olefin resin such as polyethylene or polypropylene used for molding squeeze containers, etc.

In addition, with regard to resin compositions containing liquid components, the examples of Patent Document 3 describe adding 5% of a fatty acid ester of polyglycerin (liquid component) to polyethylene or polypropylene, preparing resin composition pellets using an extrusion molding machine, and mixing the resin composition pellets with polyethylene or polypropylene resin pellets and extruding them to form a film. However, in Patent Document 3, since the concentration of the liquid component polyglycerin is low at 5%, molding resin compositions formed from this resin composition are limited to those with a fairly low concentration (in the examples of Patent Document 3, all concentrations are 1.5% or less), and it is not possible to prepare molding resin compositions containing liquid components at high concentrations.

Patent Document 4 discloses a resin composition in which 100 parts by weight of a crystalline thermoplastic resin such as polypropylene is mixed with 1 to 30 parts by weight of an antistatic agent and 0.1 to 1 part by weight of a crystal nucleating agent (component C). Examples of the antistatic agent include nonionic surfactants such as fatty acid esters of glycerin. That is, the technology of Patent Document 4 suppresses the amount of bleeding of the antistatic agent by crystallizing the crystalline thermoplastic resin, thereby preventing stickiness due to the bleeding of the antistatic agent. However, in this technology, the content of the antistatic agent per resin composition is approximately 20% by mass, but the amount of bleeding with respect to the master batch pellets is merely suppressed to about 7 to 9% by mass (about 35 to 45% by mass of the antistatic agent contained). Furthermore, the antistatic agent mixed here is used to prevent adhesion of dust and the like, and is not used to improve the slipperiness of a fluid material, so it does not form a liquid layer with liquid repellency on the surface. In other words, for resin compositions that do not contain a large amount of antistatic agent but contain a large amount of liquid, such as a lubricating liquid that forms a liquid layer with liquid repellency, further ingenuity is required to prevent stickiness.

Furthermore, in Patent Document 5, the applicant has proposed a resin composition characterized in that a liquid (B) having a viscosity (23°C) of 1000 mPa·s or less is dispersed in a matrix resin (A) having a glass transition point of 35°C or higher. This resin composition contains a lubricating liquid (liquid (B)) for improving the slipperiness against a flowable substance, and the bleeding of the liquid (B) is suppressed by using a matrix resin (A) having a high glass transition point, and the bleeding suppression effect is extremely high. However, the matrix resin with a high glass transition point used in Patent Document 5 is a cyclic olefin resin, which is extremely expensive and has the disadvantage that it cannot be applied to inexpensive propylene resins such as ordinary polypropylene or copolymers of propylene and α-olefin.

JP 2008-222291 A WO2014/010534 publication Special Publication No. 43-8605 JP 2012-72335 A JP 2015-105308 A

Therefore, an object of the present invention is to provide a resin composition in which bleeding of the lubricating liquid is effectively suppressed for a long period of time even when the lubricating liquid is contained in a high concentration. Another object of the present invention is to provide a resin composition in which a lubricating liquid is dispersed in an inexpensive propylene-based resin.

The inventors conducted numerous experiments on lubricating liquid-containing resin compositions and investigated their bleeding properties. As a result, they discovered that when a lubricating liquid is blended with a propylene-based resin, fine spherulites are uniformly generated in large quantities, significantly suppressing the bleeding of the lubricating liquid, which led to the completion of the present invention.

That is, the present invention includes the following inventions.
1. A resin composition comprising a propylene-based resin (component A), a lubricating liquid (component B) and a crystal nucleating agent (component C), the content of the component B being 10 parts by mass or more per 100 parts by mass of the component A,
The component A is a random copolymer with an α-olefin,
the component B is liquid at 23° C., and when 3 μl of distilled water is dropped onto the surface of a film formed from the component B at 23° C. and 50% RH, the contact angle 10 seconds after the drop is dropped is 70° or more;
the resin composition is in the form of pellets, the maximum spherulite diameter at the center of the pellet is 0.1 μm or more and 30 μm or less, and an X-ray diffraction peak derived from a γ-type crystal of a propylene-based resin is observed;
The resin composition is characterized in that it is a resin composition for molding a container having a liquid phase of the component B on the surface thereof .
2. The resin composition according to the above item 1 , wherein the lubricating liquid (component B) is at least one selected from the group consisting of glycerin fatty acid esters, edible oils, and combinations thereof.
3. The resin composition according to item 1 or 2 above, wherein the viscosity of the lubricating liquid (component B) at 25° C. is 1 mPa·s or more and 1000 mPa·s or less.

4. The resin composition according to any one of items 1 to 3 above, wherein the degree of crystallinity calculated from the enthalpy of fusion measured by a differential scanning calorimeter (DSC) is 10% or more and 60% or less.
5. The resin composition according to any one of the preceding items 1 to 4, wherein the crystal nucleating agent (component C) is at least one selected from the group consisting of nonitol-based nucleating agents, sorbitol-based nucleating agents, phosphate-based nucleating agents, triaminobenzene derivative-based nucleating agents, carboxylate metal salt-based nucleating agents, and xylitol-based nucleating agents.
6. The resin composition according to any one of items 1 to 5 above, wherein the surface bleed rate represented by the following formula (1) is 10% or less:
Surface bleed rate (%) = ^B60 / ^B0 × 100 (1)
B ⁰ : Amount (parts by mass) of lubricating liquid (component B) in 1 part by mass of the resin composition at the start of storage
B ⁶⁰ : The amount (parts by mass) of lubricating liquid (component B) on the surface of 1 part by mass of the resin composition after storage for 60 days in an environment of 22° C. and 60% RH

The resin composition of the present invention can effectively suppress bleeding for a long period of time. In particular, as shown in the examples described below, when a resin composition containing a large amount of lubricating liquid (component B) of 20% by mass was stored for 60 days, the amount of bleeding per part by mass of the resin composition was extremely small, and stickiness due to bleeding of the lubricating liquid (component B) can be effectively prevented. Furthermore, when a specific resin is blended with this resin composition to form a molding resin, the amount of lubricating liquid (component B) in the molding resin can be stably maintained, and modification by this lubricating liquid (component B) can be performed as designed.

The resin composition of the present invention is a mixture of a propylene-based resin (component A) and a crystal nucleating agent (component C). When a matrix resin containing the propylene-based resin and a lubricating liquid (component B) are melt-kneaded and cooled, many fine spherulites are uniformly generated. The lubricating liquid (component B) dissolved in the amorphous portion between the spherulites is trapped by these many fine spherulites, effectively suppressing bleeding.

3 is an optical microscope photograph of a central cross section of the resin composition of Example 1. Optical microscope photograph of the central cross section of the resin composition of Example 2 4 is an optical microscope photograph of a central cross section of the resin composition of Example 3. 3 is an optical microscope photograph of a central cross section of the resin composition of Comparative Example 1. 4 is an optical microscope photograph of a central cross section of the resin composition of Comparative Example 2. 4 is an optical microscope photograph of a central cross section of the resin composition of Comparative Example 3.

The resin composition of the present invention contains a propylene-based resin (component A), a lubricating liquid (component B), and a crystal nucleating agent (component C).

<Lubricating fluid (B component)>
The lubricating liquid (component B) is liquid at 23°C, and when 3 μl of distilled water is deposited on the surface of a film formed by the lubricating liquid (component B) at 23°C and 50% RH, the contact angle 10 seconds after the deposition is 70° or more.
When this resin composition is mixed with a molding resin to produce a molded body, the lubricating liquid (component B) forms a liquid layer on the surface of the molded body, and this liquid layer allows the surface of the molded body to exhibit surface characteristics according to the type of lubricating liquid (component B). Therefore, the lubricating liquid (component B) naturally has a boiling point that does not volatilize at atmospheric pressure, for example a boiling point higher than 200°C, and is selected according to the surface characteristics to be imparted to the molded body surface.

For example, when water repellency is to be imparted, the oil may be selected from silicone oil, glycerin fatty acid ester, vegetable oil (or edible oil or fat), and the like.
Furthermore, when oil repellency is to be imparted, highly hydrophilic ionic liquids and the like can be used, and an appropriate liquid may be selected taking into consideration the application of the molded article.

Furthermore, when the molded article is a container and it is desired to improve the slipperiness of the viscous contents, the lubricating liquid (component B) used is selected to be immiscible with the contents and not mixed with the contents. If the lubricating liquid (component B) is miscible with the contents, the lubricating liquid (component B) exposed on the inner surface of the container will mix with the contents and drop off from the inner surface of the container, making it difficult to impart the desired surface characteristics.
In particular, in the case of such contents containing water, such as ketchup, silicone oil, glycerin fatty acid ester, liquid paraffin, vegetable oil, etc. are preferably used as the lubricating liquid (B component). Among them, medium chain fatty acid triglycerides (those with C numbers of 6 to 12 are commercially available), glycerin fatty acid esters represented by glycerin trioleate and glycerin diacetomonooleate, and vegetable oils are difficult to volatilize, and are approved as food additives, and further have the advantage of being odorless and not impairing the flavor of the contents. In particular, medium chain fatty acid esters (MCT) are optimal in that they easily satisfy the above-mentioned temperature conditions.
For emulsion-based contents such as mayonnaise, silicone oil, glycerin fatty acid ester, vegetable oil, etc. are suitable as lubricating liquids (component B), and among them, lubricating liquids (component B) that have a property of taking time to emulsify are the most suitable. Among these, lubricating liquids that have such a property are those with a relatively high molecular weight.
The lubricating liquid (component B) is preferably at least one selected from the group consisting of glycerin fatty acid esters, edible oils, and combinations thereof.
The lubricating liquid (component B) preferably has a viscosity at 25° C. of 1 mPa·s or more and 1000 mPa·s or less.

In the present invention, the above-mentioned lubricating liquid (component B) bleeds so as to form a liquid layer on the surface of the molded body when the resin composition is diluted with a specified molding resin and molded, so that it is preferable that the amount of the lubricating liquid (component B) is large. However, if the amount of the lubricating liquid is too large, the effect of the crystal nucleating agent (component C) during molding of the resin composition is reduced, and there is a possibility that bleeding of the lubricating liquid (component B) from the resin composition cannot be effectively suppressed.
Therefore, the content of the lubricating liquid (component B) is preferably in the range of 10 parts by mass or more and less than 100 parts by mass, more preferably 20 parts by mass or more and less than 70 parts by mass, and even more preferably 25 parts by mass or more and less than 40 parts by mass, per 100 parts by mass of the propylene-based resin (component A).

<Propylene-based resin (component A)>
In the present invention, a propylene-based resin (component A) is used as the matrix resin for dispersing the lubricating liquid (component B). By using the propylene-based resin (component A) as the matrix resin, it is possible to adjust the crystallinity so as to satisfy a predetermined maximum spherulite diameter.

As such a propylene-based resin (component A), not only a propylene homopolymer but also a random or block copolymer of propylene and a linear α-olefin such as ethylene, butene-1, hexene-1, or 4-methyl-1-pentene can be used depending on the application. From the viewpoint of crystallinity, it is desirable that the propylene content in the copolymer is 90 mol% or more, and particularly 95 mol% or more. From the viewpoint of moldability, it is also desirable that the MFR (230°C) is in the range of 0.1 g/10 min or more and less than 26 g/10 min, more preferably in the range of 0.3 to 10 g/10 min.

As long as the specified maximum spherulite diameter can be ensured, a resin blended with other thermoplastic resins other than the above propylene-based resins can also be used as the matrix resin. Such other thermoplastic resins are not particularly limited, but generally, from the viewpoint of moldability, olefin-based resins can be mentioned, for example, polyethylene and copolymers of ethylene and other α-olefins, and the blend amount in the matrix resin is preferably 30 mass% or less.

<Crystal nucleating agent (component C)>
The resin composition of the present invention contains a crystal nucleating agent (component C). Examples of the crystal nucleating agent (component C) include those known as crystal nucleating agents for polypropylene, such as carboxylate metal salts such as sodium benzoate, aluminum dibenzoate, potassium benzoate, lithium benzoate, and sodium β (naphthalate sodium cyclohexane carboxylate), sorbitol types such as benzylidene sorbitol and its derivatives, and polymer types such as poly-3-methylbutene-1, polyvinyl cycloalkane, and polyvinyl trialkylsilane.
The crystal nucleating agent (component C) is preferably at least one selected from the group consisting of nonitol-based nucleating agents, sorbitol-based nucleating agents, phosphate-based nucleating agents, triaminobenzene derivative-based nucleating agents, metal carboxylate-based nucleating agents, and xylitol-based nucleating agents.
The above-mentioned crystal nucleating agent (component C) is generally blended with a propylene-based resin and is commercially available. For example, such a propylene-based resin containing a crystal nucleating agent (component C) is commercially available under the trade names of Random Polypropylene PM931M manufactured by SunAllomer Co., Ltd. and Random Polypropylene PM731M manufactured by SunAllomer Co., Ltd.

The crystal nucleating agent (component C) is preferably a nonitol-based nucleating agent, for example, 1,2,3-trideoxy-4,6:5,7-O-bis(4-propylbenzylidene)nonitol represented by the following formula.

The content of the crystal nucleating agent (component C) in the resin composition is preferably in the range of 0.10 parts by mass or more and less than 1.0 parts by mass, more preferably 0.15 parts by mass or more and less than 0.9 parts by mass, and even more preferably 0.20 parts by mass or more and less than 0.80 parts by mass per 100 parts by mass of the propylene-based resin (component A).

<Resin composition>
(Size of resin composition)
When the resin composition is in the form of pellets having a cylindrical shape, the size of the pellets is preferably, from the viewpoint of ensuring a predetermined maximum spherulite diameter, a diameter of 10 mm or less, 5 mm or less, or even 3 mm or less, and a length of 20 mm or less, 10 mm or less, or even 5 mm or less. The lower limit of each is not particularly limited, but is preferably 1 mm.
(Maximum spherulite diameter)
The maximum spherulite diameter at the center of the resin composition of the present invention is 0.1 μm or more and 30 μm or less. The upper limit of the maximum spherulite diameter at the center of the resin composition is preferably smaller from the viewpoint of suppressing bleeding of the liquid, and is preferably, for example, 30 μm or less, 15 μm or less, or even 5 μm or less. The lower limit is not particularly limited, but is preferably 0.1 μm. In this specification, the maximum spherulite diameter means the maximum diameter of the spherulite present in the central cross section of the resin composition, and can be measured using a polarizing microscope or a transmission electron microscope (TEM).

(Crystallization degree)
From the viewpoint of suppressing bleeding of the lubricating liquid (component B), the crystallinity of the resin composition is preferably as high as possible. However, if the crystallinity is too high, the proportion of amorphous parts decreases, and the amount of the lubricating liquid (component B) that can be saturated and dissolved in the propylene-based resin (component A) may decrease, or the processability during granulation may decrease.
Therefore, the crystallinity of the resin composition determined from the enthalpy of fusion measured by a differential scanning calorimeter (DSC) is preferably 15% or more and 60% or less, more preferably 20% or more and 57% or less, and even more preferably 25% or more and 54% or less.
The degree of crystallinity means a value calculated from the ratio of the melting enthalpy of a resin composition measured by a differential scanning calorimeter (DSC) to the melting enthalpy of a perfect crystal of the resin composition.

(X-ray diffraction peaks derived from γ-type crystals)
The resin composition is preferably observed to have an X-ray diffraction peak derived from the γ-type crystal of the propylene resin. The reason why the diffusion of the lubricating liquid is suppressed is not clear, but it is known that the γ-type crystal grows from the side of the α-type crystal (010), and this is assumed to be because the densified spherulite is formed, and the diffusion of the lubricating liquid present inside the spherulite is inhibited.

(Surface bleed rate)
The resin composition of the present invention preferably has a surface bleeding rate represented by the following formula (1) of 10% or less, more preferably 8% or less.
Surface bleed rate (%) = ^B60 / ^B0 × 100 (1)
B ⁰ : Amount (parts by mass) of lubricating liquid (component B) in 1 part by mass of the resin composition at the start of storage
B ⁶⁰ : Amount (parts by mass) of lubricating liquid (component B) on the surface of 1 part by mass of the resin composition after storage for 60 days in an environment of 22° C. and 60% RH
The surface bleeding rate is calculated from the amount of lubricating liquid (component B) on the surface of the resin composition after 8 g of the resin composition is placed in a glass bottle and stored for 60 days in an environment of 22° C. and 60% RH.

Preparation and Use of Resin Compositions
The resin composition of the present invention is prepared by feeding predetermined amounts of a propylene-based resin (component A), a lubricating liquid (component B) and a crystal nucleating agent (component C) to, for example, a kneading section of an extruder, kneading the mixture, melt-extruding the mixture, cutting the mixture into pellets of a predetermined size using a pelletizer, etc., and storing, transporting or selling the mixture before use. In other words, the lubricating liquid (component B) effectively prevents bleeding of the mixture and the pellets from becoming sticky during the period immediately after production and before use.
The resin composition is preferably in the form of pellets. The pellets of the resin composition can also be used as two-layer pellets, in which the core layer is made of the propylene-based resin (component A) containing the crystal nucleating agent (component C) in which the lubricating liquid (component B) is dispersed, as long as the predetermined maximum spherulite diameter can be ensured.

The pellets of this resin composition are particularly used to mold a molded article having a liquid layer of lubricating liquid (component B) formed on the surface. That is, the pellets of this resin composition are kneaded with a molding resin (diluted resin) to prepare a kneaded product containing the lubricating liquid (component B) at a predetermined concentration, and the kneaded product is molded into a predetermined shape to obtain the desired molded article. In addition, when the molded article is a multilayer structure, the pellets of this resin composition can be mixed with a molding resin (diluted resin) and used not only to form a liquid layer on the surface, but also, for example, to adjust the concentration of the lubricating liquid (component B) in any layer in the multilayer structure.

There are no particular limitations on the molding resin to be mixed with the resin composition pellets, so long as it can be mixed uniformly with the propylene-based resin (component A), but in general, olefin-based resins of the same type as the propylene-based resin (component A), such as propylene-based resins and polyethylene, are preferably used. This is because it is easy to set molding conditions and it is possible to obtain a molded product that makes the most of the resin's properties.

The kneading and molding means can be appropriately selected depending on the physical properties of the resin (e.g., melt flow rate), but from the viewpoint of kneading the liquid with the solid matrix resin, it is preferable to knead the two by melt kneading in a kneading section of a molding machine such as an extruder, and the molding means is preferably extrusion molding or extrusion blow molding (direct blow molding). This is because such means can effectively avoid the loss of the lubricating liquid (component B) during kneading and molding, and furthermore, the effect of the presence of the lubricating liquid (component B) on molding (e.g., adhesion of the liquid to the mold, etc.) can be ignored.

Such a resin composition mainly composed of a propylene-based resin (component A) and containing a lubricating liquid (component B) is suitable for use in molding flexible containers such as squeeze containers (direct blow bottles) that squeeze out viscous contents, and when the resin composition of the present invention is used in molding such flexible containers, the surface characteristics of the liquid layer of the lubricating liquid (component B) can be maximized. Of course, it can also be applied to molding containers having various shapes such as cups or glass-shaped, bottle-shaped, bag-shaped (pouch), syringe-shaped, pot-shaped, tray-shaped, etc., and can also be applied to stretch-molded containers.

The excellent properties of the resin composition of the present invention will be explained in the following examples. The methods for measuring various physical properties and characteristics and the preparation of the resin composition used in the following examples are as follows.

1. Measurement of maximum spherulite diameter Using an optical microscope (LSM5 Pascal: Carl Zeiss), the central cross section of the resin composition was observed in a cross-Nicol state at a magnification of 50x or 100x, and the maximum diameter in the major axis direction of the observed spherulites was measured.

2. Crystallinity Measurement The crystallinity measurement was performed using a differential scanning calorimeter (DSC 2500 manufactured by TA Instruments). A sample filled with 3 mg of sample in a sample pan was held at 25°C for 3 minutes under a nitrogen atmosphere, and then cooled to -40°C at a temperature drop rate of 50°C/min. Next, after holding at -40°C for 3 minutes, the sample was heated from -40°C to 200°C at a temperature rise rate of 10°C/min. The melting enthalpy ΔH (J/g) of the sample was obtained from the peak area surrounded by the melting peak observed on the highest temperature side during the heating process and the baseline drawn in the range from 20°C to 180°C, and the crystallinity was calculated by the following formula.
Crystallinity (%) = ΔH/(ΔH0×φ)×100
ΔH0 is the melting enthalpy of the perfect crystal of the propylene-based resin, and φ is the weight fraction of the propylene-based resin. Here, the melting enthalpy of the perfect crystal of the propylene-based resin was set to 207 J/g.

3. Confirmation of the formation of γ-type crystals The formation of γ-type crystals in the propylene-based resin was confirmed using an X-ray diffraction measurement device (Rigaku Corporation, SmartLab). The sample was placed on a glass sample holder with a depth of 0.2 mm, and measurements were performed under the following conditions. From the obtained X-ray diffraction profile, the presence or absence of a peak at a diffraction angle (2θ) of around 20.3°, which is a peak derived from γ-type crystals, was confirmed.
Tube voltage: 45 kV,
・Tube current: 200mA
・X-ray source: Cu-Kα ray (1.5418 Å),
Optical system: focusing method Entrance slit 1/3 degree, length limiting slit: 10 mm, receiving slit 1: open, receiving slit 2: 20 mm
Scan mode: 2θ/θ scan 2θ scan range: 5 to 40 degrees Angle step width: 0.01 degrees Scan speed: 5 degrees/min Detector: HyPix-3000

4. Evaluation of the amount of surface bleeding of the resin composition 8 g of the resin composition prepared by the method described below was placed in a glass bottle and stored for 60 days under an environment of 22 ° C. and 60% RH. 8 g of heptane was added to the glass bottle containing the resin composition stored over time and stirred for 10 seconds, and the liquid on the surface of the resin composition was washed and collected. After drying the heptane at 120 ° C., the weight of the remaining liquid was measured and divided by the weight of the resin composition added to calculate the amount of surface bleeding of the lubricating liquid (B component) per 1 g of the resin composition, and the surface bleeding rate represented by the following formula (1) was obtained.
Surface bleed rate (%) = ^B60 / ^B0 × 100 (1)
B ⁰ : Amount (parts by mass) of lubricating liquid (component B) in 1 part by mass of the resin composition at the start of storage
B ⁶⁰ : Amount (parts by mass) of lubricating liquid (component B) on the surface of 1 part by mass of the resin composition after storage for 60 days in an environment of 22° C. and 60% RH

The following materials were used:
<Propylene-based resin (component A)>
Propylene-based resin A: Random polypropylene (propylene:ethylene = 96:4 (mol)), PC630A manufactured by SunAllomer Corporation
Propylene-based resin B: homopolypropylene, PM600A manufactured by SunAllomer Co., Ltd.

<Lubricating fluid (B component)>
Medium Chain Triglycerides (MCT)
Water contact angle: 81°
Viscosity: 24mPa・s
The water contact angle with respect to the liquid film was determined by depositing a drop of 3 μl of distilled water on the surface of a liquid film formed on an LDPE film (LDPE-F120N, manufactured by Ube Maruzen Polyethylene Co., Ltd.) at 23° C. and 50% RH using a solid-liquid interface analysis system DropMaster 700 (manufactured by Kyowa Interface Science Co., Ltd.) and measuring the contact angle 10 seconds after the drop was deposited.
The viscosity of the lubricating liquid was measured at 25° C. using a Brookfield DV2T type viscometer.

<Crystal nucleating agent (component C)>
Nonitol-based nucleating agent (Millad NX8000E (Milliken Japan))

Example 1
Propylene-based resin A was used as the propylene-based resin (A component), medium-chain fatty acid triglyceride (MCT) was used as the lubricating liquid (B component), and Millad NX8000E (Milliken Japan) was used as the crystal nucleating agent (C component). Here, the crystal nucleating agent (C component) was used that was melt-kneaded with the propylene-based resin (A component) in advance to form a master batch of 12% by mass. Melt-kneading was performed under the condition of a cylinder temperature of 220 ° C. using a twin-screw kneading extruder (KZW20TW manufactured by Technovel Co., Ltd.) so that the ratio of propylene-based resin A: MCT: crystal nucleating agent = 100: 25: 0.30 (parts by mass). The kneaded product was extruded into a strand shape, air-cooled, and then pelletized to prepare a pellet-shaped resin composition having a cylindrical shape with a diameter of 2.5 mm and a length of 3 mm.

Example 2
A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that the ratio of propylene-based resin A:MCT:crystal nucleating agent was 100:25:0.15 (parts by mass).

Example 3
A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that the ratio of propylene-based resin B:MCT:crystal nucleating agent was 100:25:0.30 (parts by mass).

<Comparative Example 1>
A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that the ratio of propylene-based resin A:MCT:crystal nucleating agent was 100:25:0 (parts by mass).

<Comparative Example 2>
A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that the ratio of propylene-based resin B:MCT:crystal nucleating agent was 100:25:0 (parts by mass).

<Comparative Example 3>
A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that the ratio of propylene-based resin B:MCT:crystal nucleating agent was 100:25:0.15 (parts by mass).

The maximum spherulite size, crystallinity, and γ crystal peak were measured for the resin compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 3 above, and the amount of bleeding was also measured, and these results are shown in Table 1. From the results of the surface bleeding rate evaluation of the resin compositions in Examples 1 to 3, it can be seen that the surface bleeding of the blended liquid was suppressed compared to Comparative Examples 1 to 3.
1 to 6 show optical microscope photographs of the resin compositions of Examples 1 to 3 and Comparative Examples 1 to 3.

Claims (6)

A resin composition comprising a propylene-based resin (component A), a lubricating liquid (component B) and a crystal nucleating agent (component C), the content of the component B being 10 parts by mass or more per 100 parts by mass of the component A,
The component A is a random copolymer with an α-olefin,
the component B is liquid at 23° C., and when 3 μl of distilled water is dropped onto the surface of a film formed from the component B at 23° C. and 50% RH, the contact angle 10 seconds after the drop is dropped is 70° or more;
the resin composition is in the form of pellets, the maximum spherulite diameter at the center of the pellet is 0.1 μm or more and 30 μm or less, and an X-ray diffraction peak derived from a γ-type crystal of a propylene-based resin is observed;
The resin composition is characterized in that it is a resin composition for molding a container having a liquid phase of the component B on the surface thereof . 2. The resin composition according to claim 1 , wherein the lubricating liquid (component B) is at least one selected from the group consisting of glycerin fatty acid esters, edible oils, and combinations thereof. 3. The resin composition according to claim 1 , wherein the lubricating liquid (component B) has a viscosity at 25°C of 1 mPa·s or more and 1000 mPa·s or less. 4. The resin composition according to claim 1 , wherein the degree of crystallinity determined from the enthalpy of fusion measured by a differential scanning calorimeter (DSC) is 10% or more and 60% or less. The resin composition according to any one of claims 1 to 4, wherein the crystal nucleating agent (component C) is at least one selected from the group consisting of nonitol-based nucleating agents, sorbitol-based nucleating agents, phosphate-based nucleating agents, triaminobenzene derivative-based nucleating agents, carboxylate metal salt-based nucleating agents, and xylitol-based nucleating agents. The resin composition according to any one of claims 1 to 5 , which has a surface bleeding rate represented by the following formula (1) of 10% or less.
Surface bleed rate (%) = ^B60 / ^B0 × 100 (1)
B ⁰ : Amount (parts by mass) of lubricating liquid (component B) in 1 part by mass of the resin composition at the start of storage
B ⁶⁰ : The amount (parts by mass) of lubricating liquid (component B) on the surface of 1 part by mass of the resin composition after storage for 60 days in an environment of 22° C. and 60% RH