Propylene-based resin composition

Abstract

To provide a liquid-containing resin composition where the bleeding of liquid being effectively suppressed for a long time even when that the liquid is contained in high concentrations.SOLUTION: A resin composition contains a propylene resin (A component), a lubricant liquid (B component) and a crystal nucleating agent (C component) with the content of the B component being 10 pts.mass or more relative to 100 pts.mass of the A component. The B component is liquid at 23°C. When droplets of 3 μl distilled water are made to land on the surface of a film formed from the B component at 23°C, 50% RH, the contact angle is 70° or more 10 seconds after the landing of the droplets. In the resin composition, the central spherocrystals have a maximum size of 0.1 μm or more and 30 μm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a propylene-based resin composition, and more particularly to a propylene-based resin composition containing a lubricating liquid.

Background Art

[0002] Plastic containers are widely used in various applications because they are easy to mold and can be manufactured at low cost. For example, olefin-based resins such as polyethylene and polypropylene are suitably used for molding bottles for containing viscous slurry-like or paste-like contents such as ketchup.

[0003] By the way, in containers such as bottles that contain viscous contents, in order to quickly discharge the contents or to use them up completely without leaving any residue in the container, when the container is inverted, it is desired that the viscous contents quickly fall without adhering to the inner surface of the container.

[0004] In order to satisfy such requirements, in the past, as described in Patent Document 1, a solid lubricant such as aliphatic amide was blended on the inner surface of the resin forming the inner surface of the container, and the lubricant bled onto the inner surface of the container, thereby improving the slipperiness of the container contents. This method has been adopted.

[0005] However, recently, as described in Patent Document 2, a method of forming a layer of a liquid different from the contents on the inner surface in contact with the contents has attracted attention. In such a method, by forming a liquid layer of a liquid immiscible with the contents on the inner surface of the container, the slipperiness with respect to the contents can be significantly improved as compared with the conventionally known ones, and by inverting or tilting the container, the contents can be quickly discharged outside the container without adhering to and remaining on the inner wall of the container. The method of modifying surface properties such as slipperiness by forming a liquid layer on the surface in this way is applicable not only to the form of a container but also to a molded body having a form such as a film. By appropriately selecting the type of liquid, the surface properties can be significantly modified.

[0006] However, as described above, in the means of forming a liquid layer on the surface of a molded body such as a container to modify the surface properties, after the container is molded, a liquid other than the content is immersed in the inner surface of the container and applied by spraying or the like to form a liquid layer. In this case, a special treatment step is required to form the liquid layer, which is a problem in terms of productivity. For this reason, in order to form a liquid layer on the surface, the liquid for forming the liquid layer is mixed with the resin for forming the inner surface, and molding is performed using a resin composition mixed with such a liquid. The means of forming a liquid layer on the surface of the molded body by bleeding of the liquid after molding is industrially advantageous. That is, after molding, without performing any special treatment, the liquid contained in the resin composition segregates on the inner surface of the container, and thereby a liquid layer is automatically formed on the surface.

[0007] By the way, when molding a container using the above-described liquid (hereinafter sometimes referred to as a lubricating liquid)-containing resin composition, industrially, a resin composition in the form of pellets in which the lubricating liquid is blended with the molding resin is naturally used. That is, if the lubricating liquid and the molding resin are mixed each time during molding to prepare a resin composition, the efficiency is poor, and a tank for storing a large amount of the lubricating liquid is also required. Therefore, a resin composition in the form of pellets containing the lubricating liquid at a high concentration is prepared in advance, and the lubricating liquid is handled in the form of this resin composition during storage, transportation, etc. During molding, the resin composition is diluted with the molding resin to prepare a resin composition for surface formation, and molding into a container or the like is performed.

[0008] Therefore, the problem lies in the bleeding property of the lubricating fluid 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. However, when the liquid concentration of the resin composition is high, the liquid bleeds from the resin composition, causing the pellets to become sticky and difficult to handle. Also, due to the bleeding of the liquid, when preparing a resin composition for molding by diluting this, there are problems such as the liquid concentration becoming lower than the target value. This tendency is prominent in the case of olefin resins such as polyethylene and polypropylene used for molding in a squeeze container or the like, which are the molding resins mixed with the liquid.

[0009] Regarding a resin composition containing a liquid component, in the examples of Patent Document 3, it is described that 5% of a fatty acid ester of polyglycerin (liquid component) was added to polyethylene or polypropylene, resin composition pellets were prepared using an extrusion molding machine, and a film was formed by extrusion after mixing these resin composition pellets with resin pellets of polyethylene or polypropylene. However, in this Patent Document 3, since the concentration of polyglycerin, which is the liquid component, is as low as 5%, the resin composition for molding formed from this resin composition is limited to those with a considerably low concentration (in the examples of Patent Document 3, all are 1.5% or less), and a resin composition for molding containing a liquid component at a high concentration cannot be prepared.

[0010] In addition, Patent Document 4 discloses a resin composition in which 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) are blended with 100 parts by weight of a crystalline thermoplastic resin such as polypropylene. Examples of this antistatic agent include nonionic surfactants such as fatty acid esters of glycerin. That is, the technique of this Patent Document 4 suppresses the bleeding amount of the antistatic agent by crystallizing the crystalline thermoplastic resin, and prevents stickiness due to bleeding of the antistatic agent. However, in this technique, although the content of the antistatic agent per resin composition is approximately 20% by mass, the bleeding amount with respect to the masterbatch pellets is only suppressed to about 7 to 9% by mass (about 35 to 45% by mass with respect to the contained antistatic agent). Furthermore, the antistatic agent blended here is used to prevent adhesion of dust and the like, and is not used to improve the slipperiness of fluid substances, so a liquid layer having liquid repellency is not formed on the surface. That is, for a resin composition in which a large amount of an antistatic agent is not blended and a large amount of liquid such as a lubricating liquid having liquid repellency is blended, further improvement is required to prevent stickiness.

[0011] Furthermore, Patent Document 5 proposes 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 by the present applicant. This resin composition contains a lubricating liquid (liquid (B)) for improving the slipperiness with respect to fluid substances, and suppresses the bleeding of liquid (B) by using a matrix resin (A) having a high glass transition point, and the bleeding suppression effect is extremely high. However, the matrix resin having a high glass transition point used in this Patent Document 5 is a cyclic olefin resin, which is extremely expensive and has the drawback that it cannot be applied to inexpensive propylene resins such as ordinary polypropylene or copolymers of propylene and α-olefins.

Prior Art Documents

Patent Documents

[0012] Patent Document 1 Japanese Patent Application Laid-Open No. 2008-222291 Patent Document 2 WO2014 / 010534 Publication Patent Document 3 Japanese Patent Publication No. 43-8605 Patent Document 4 Japanese Patent Application Laid-Open No. 2012-72335 Patent Document 5 Japanese Patent Application Laid-Open No. 2015-105308 Summary of the Invention Problems to be Solved by the Invention

[0013] Accordingly, an object of the present invention is to provide a resin composition in which bleeding of the lubricating fluid is effectively suppressed over a long period even when the resin composition contains a high concentration of the lubricating fluid. Another object of the present invention is to provide a resin composition in which a lubricating fluid is dispersed in an inexpensive propylene-based resin. Means for Solving the Problems

[0014] As a result of conducting many experiments on the lubricating fluid-containing resin composition and examining its bleeding property, the present inventors have found that when a lubricating fluid is blended with a propylene-based resin, bleeding of the lubricating fluid can be significantly suppressed by uniformly generating a large number of fine spherulites, and have thus completed the present invention.

[0015] That is, the present invention includes the following inventions. 1. A resin composition containing a propylene-based resin (component A), a lubricating fluid (component B), and a crystal nucleating agent (component C), wherein the content of the component B is 10 parts by mass or more with respect to 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 the film formed by the component (B) at 23°C and 50% RH, the contact angle after 10 seconds of dropping is 70° or more. The resin composition is in pellet form, and the The maximum spherulite diameter at the center is 0.1 μm or more and 30 μm or less. and an X-ray diffraction peak derived from the γ-type crystal of the propylene-based resin is observed, It is a resin composition for forming a container having a liquid phase of the component B on the surface The resin composition characterized by the above. 2 . The resin composition according to the preceding paragraph, 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. 1 to described resin composition. 3 . The resin composition according to item 1 of the preceding paragraph, wherein the viscosity of the lubricating liquid (component (B)) at 25°C is 1 mPa·s or more and 1000 mPa·s or less. or 2 described resin composition.

[0016] 4 . The resin composition according to any one of items 1 to 3 wherein the crystallinity determined from the melting enthalpy measured by a differential scanning calorimeter (DSC) is 10% or more and 60% or less. 5 . The resin composition according to any one of 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 ester-based nucleating agents, triaminobenzene derivative-based nucleating agents, carboxylic acid metal salt-based nucleating agents, and xylitol-based nucleating agents. 6 . The resin composition according to any one of items 1 to 5 wherein the surface bleed rate represented by the following formula (1) is 10% or less. Surface bleed rate (%) = B 60 / B 0 ×100 (1) B 0 : The amount (parts by mass) of the 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 the 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

Advantages of the Invention

[0017] The resin composition of the present invention can effectively suppress bleeding over a long period. In particular, as shown in the examples described later, when a resin composition containing as much as 20% by mass of a lubricating liquid (Component B) was stored for 60 days, the bleeding amount per 1 part by mass of the resin composition was extremely small, and stickiness due to bleeding of the lubricating liquid (Component B) could be effectively prevented. Further, when a predetermined resin was blended with this resin composition to obtain a molding resin, the amount of the lubricating liquid (Component B) in the molding resin could be stably maintained, and modification by this lubricating liquid (Component B) could be carried out as designed.

[0018] In the resin composition of the present invention, a crystal nucleating agent (Component C) is blended in a propylene-based resin (Component A). When the matrix resin containing the propylene-based resin and the lubricating liquid (Component B) are melt-kneaded and cooled, it means that a large number of fine spherulites are uniformly formed. The lubricating liquid (Component B) dissolved in the amorphous part between the spherulites is confined by such a large number of fine spherulites, and its bleeding is effectively suppressed.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0020] 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).

[0021] <Lubricating liquid (component B)> The lubricating liquid (component B) is liquid at 23°C, and when 3 μl of distilled water is dropped onto the surface of the film formed by the lubricating liquid (component B) at 23°C and 50% RH, the contact angle 10 seconds after dropping is 70° or more. When the lubricating liquid (component B) is mixed with the resin for molding to produce a molded body, a liquid layer in which the lubricating liquid (component B) is deposited is formed on the surface thereof, and such a liquid layer causes the surface characteristics corresponding to the type of the lubricating liquid (component B) to be exhibited on the surface of the molded body. Therefore, such a 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 surface of the molded body.

[0022] For example, when attempting to impart water repellency, it is selected from silicone oil, glycerin fatty acid ester, vegetable oil (or edible oil), etc. Also, when attempting to impart oil repellency, an ionic liquid with high hydrophilicity or the like can be used, and an appropriate liquid can be selected in consideration of the use of the molded body.

[0023] Furthermore, when the molded body is a container and it is desired to enhance the slipperiness with respect to a viscous content, the lubricating liquid (component B) to be used is selected to be immiscible with the content and not to mix with the content. This is because if it is miscible with the content, the lubricating liquid (component B) exposed on the inner surface of the container will mix with the content and fall off from the inner surface of the container, making it difficult to impart the desired surface characteristics. In particular, for such contents that contain moisture, such as ketchup, as the lubricating liquid (Component B), silicone oil, glycerin fatty acid ester, liquid paraffin, vegetable oil, etc. are preferably used. Among them, medium-chain fatty acid triglycerides (those with 6 to 12 carbon atoms are commercially available), glycerin fatty acid esters represented by glycerin trioleate and glycerin diacetomonooleate, and vegetable oils are difficult to volatilize, and moreover, they are approved as food additives, and further, they have the advantages 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-described temperature conditions. Also, for emulsified contents such as mayonnaise, silicone oil, glycerin fatty acid ester, vegetable oil, etc. are suitable as the lubricating liquid (Component B), and among them, the lubricating liquid (Component B) that exhibits the property of having time for emulsification is optimal. Those having such properties are relatively high in molecular weight among these. 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.

[0024] In the present invention, since the above-described lubricating liquid (Component B) bleeds so that a liquid layer is formed on the surface of the molded article when the resin composition is diluted with a predetermined molding resin and molded, its blending amount is preferably large. However, if the blending amount is too large, the effect of the crystal nucleating agent (Component C) during the molding of the resin composition becomes small, and bleeding of the lubricating liquid (Component B) from the resin composition may not 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, still 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).

[0025] <Propylene-based resin (Component A)> In the present invention, a propylene-based resin (Component A) is used as the matrix resin for dispersing the above lubricating fluid (Component B). By using the propylene-based resin (Component A) as the matrix resin, the crystallinity can be adjusted so as to satisfy a predetermined maximum spherulite diameter.

[0026] As such a propylene-based resin (Component A), depending on its use, not only propylene homopolymer but also random or block copolymers of propylene and linear α-olefins such as ethylene, butene-1, hexene-1, 4-methyl-1-pentene, etc. can be used. From the viewpoint of crystallinity, the propylene content in the copolymer is desirably 90 mol% or more, particularly 95 mol% or more. Also, from the viewpoint of moldability, those having an MFR (230°C) 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, are preferred.

[0027] As long as a predetermined maximum spherulite diameter can be ensured, those in which other thermoplastic resins other than the above propylene-based resins are blended can also be used as the matrix resin. Such other thermoplastic resins are not particularly limited, but generally, olefin-based resins can be mentioned from the viewpoint of moldability. For example, polyethylene and copolymers of ethylene and other α-olefins are typical, and the blending amount thereof is preferably 30% by mass or less in the matrix resin.

[0028] <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 metal carboxylate types like sodium benzoate, aluminum dibenzoate, potassium benzoate, lithium benzoate, sodium β-(naphthalene sodium cyclohexanecarboxylate), sorbitol types like benzylidene sorbitol and its derivatives, and other 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 ester-based nucleating agents, triaminobenzene derivative-based nucleating agents, metal carboxylate-based nucleating agents, and xylitol-based nucleating agents. Incidentally, the crystal nucleating agent (Component C) as described above is generally compounded with a propylene-based resin and commercially available. For example, propylene-based resins containing such a crystal nucleating agent (Component C) are commercially available under trade names such as random polypropylene PM931M manufactured by San Allomer Co., Ltd. and random polypropylene PM731M manufactured by San Allomer Co., Ltd.

[0029] 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 can be mentioned.

Chemical formula

[0030] 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 part by mass, more preferably 0.15 parts by mass or more and less than 0.9 part by mass, and still more preferably 0.20 parts by mass or more and less than 0.80 part by mass per 100 parts by mass of the propylene-based resin (Component A).

[0031] <Resin composition> (Size of the resin composition) When the resin composition is in the form of pellets having a cylindrical shape, from the viewpoint of ensuring a predetermined maximum spherulite diameter, the diameter is preferably 10 mm or less, 5 mm or less, more preferably 3 mm or less, and the length is preferably 20 mm or less, 10 mm or less, more preferably 5 mm or less. Although the lower limit is not particularly limited, it 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. From the viewpoint of suppressing bleeding of the liquid, the upper limit of the maximum spherulite diameter at the center of the resin composition is preferably smaller, for example, preferably 30 μm or less, 15 μm or less, more preferably 5 μm or less. The lower limit is not particularly limited, but is preferably 0.1 μm. In the present specification, the maximum spherulite diameter means the maximum diameter of spherulites present in the central cross-section of the resin composition, and can be measured using a polarized light microscope or a transmission electron microscope (TEM).

[0032] (Crystallinity) The crystallinity of the resin composition is preferably larger from the viewpoint of suppressing bleeding of the lubricating liquid (Component B), but if it is too large, the proportion of the amorphous part decreases, and the saturated dissolution amount of the lubricating liquid (Component B) in the propylene-based resin (Component A) may decrease, or the processability during granulation may decrease. Therefore, the crystallinity determined from the melting enthalpy measured by differential scanning calorimetry (DSC) of the resin composition is preferably 15% or more and 60% or less, more preferably 20% or more and 57% or less, still more preferably 25% or more and 54% or less. Crystallinity means a value obtained from the ratio of the melting enthalpy of the resin composition measured by differential scanning calorimetry (DSC) to the melting enthalpy of the completely crystalline resin composition.

[0033] (X-ray diffraction peak derived from γ-type crystal) It is preferable that an X-ray diffraction peak derived from the γ-type crystal of the propylene-based resin is observed in the resin composition. The reason for suppressing the diffusion of the lubricating liquid is not clear, but it is known that the γ-type crystal grows from the (010) side face of the α-type crystal, thereby forming a densified spherulite, and it is presumed that this inhibits the diffusion of the lubricating liquid present inside the spherulite.

[0034] (Surface bleed rate) The resin composition of the present invention preferably has a surface bleed rate represented by the following formula (1) of 10% or less, more preferably 8% or less. Surface bleed rate (%) = B 60 / B 0 ×100 (1) B 0 : The amount (parts by mass) of the 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 the 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 bleed rate is calculated from the amount of the lubricating liquid (Component B) on the surface of the resin composition obtained by putting 8 g of the resin composition in a glass bottle and storing it for 60 days in an environment of 22°C and 60% RH.

[0035] <Preparation and Use of Resin Composition> The resin composition of the present invention supplies predetermined amounts of a propylene-based resin (Component A), a lubricating liquid (Component B), and a crystal nucleating agent (Component C) to, for example, the kneading section of an extruder and kneads them, melt-extrudes them, cuts the melt-extrudate with a pelletizer or the like, and uses it through storage, conveyance, or sale as pellets of a predetermined size. That is, it is effectively prevented that inconveniences such as bleeding of the lubricating liquid (Component B) and stickiness of the pellets occur between immediately after production and use. The resin composition is preferably in pellet form. The pellets of this resin composition can also be used as two-layer pellets having a propylene-based resin (Component A) containing a crystal nucleating agent (Component C) in which the above-described lubricating liquid (Component B) is dispersed as a core material layer as long as a predetermined maximum spherulite diameter can be ensured.

[0036] The pellets of this resin composition are particularly used for molding a molded article having a liquid layer formed on the surface by a lubricating liquid (Component B). That is, the resin composition pellets are kneaded with a molding resin (diluting resin) to prepare a kneaded product containing the lubricating liquid (Component B) at a predetermined concentration, and the kneaded product is used to mold into a predetermined shape, whereby the target molded article can be obtained. Further, when the molded article is composed of a multilayer structure, this resin composition pellet can be mixed with a molding resin (diluting resin) and used not only for forming a liquid layer on the surface but also for adjusting the concentration of the lubricating liquid (Component B) in an arbitrary layer in the multilayer structure, for example.

[0037] The molding resin to be mixed with the resin composition pellets is not particularly limited as long as it can be uniformly mixed with the propylene-based resin (Component A). Generally, however, an olefin-based resin of the same type as the propylene-based resin (Component A), such as a propylene-based resin or polyethylene, is preferably used. This is because it is easy to set the molding conditions, and moreover, a molded article that maximally utilizes the characteristics of the resin can be obtained.

[0038] Furthermore, as the kneading means and the molding means, appropriate means can be adopted according to the physical properties of the resin (for example, melt flow rate), etc. However, from the viewpoint of kneading a liquid with a solid matrix resin, the kneading of the two is preferably carried out by melt kneading in a kneading section in a molding machine such as an extruder. Further, as the molding means, extrusion molding or extrusion blow molding (direct blow molding) is preferably applied. Such means can effectively avoid the dissipation of the lubricating liquid (Component B) during kneading and molding, and furthermore, the influence of the presence of the lubricating liquid (Component B) on molding (for example, adhesion of the liquid to molding, etc.) can be ignored.

[0039] A resin composition mainly composed of such a propylene-based resin (component A) and containing a lubricating liquid (component B) is suitably used for forming flexible containers such as squeeze containers (direct blow bottles) for squeezing out viscous contents. When the resin composition of the present invention is used for forming such flexible containers, the surface characteristics due to the liquid layer of the lubricating liquid (component B) can be maximally utilized. Of course, it can also be applied to forming containers having various forms such as cups or cup-shaped, bottle-shaped, bag-shaped (pouch), syringe-shaped, tub-shaped, tray-shaped, etc., and can also be applied to stretch-formed containers.

Examples

[0040] The excellent properties of the resin composition of the present invention will be described in the following examples. The measurement methods of various physical properties, characteristics, etc. and the preparation of the resin composition carried out in the following examples and the like are as follows.

[0041] 1. Measurement of maximum spherulite diameter Using an optical microscope (LSM5 Pascal: Carl Zeiss), the central cross-section of the resin composition was observed at a magnification of 50 times or 100 times in a cross-Nicol state, and the maximum value of the diameter in the major axis direction of the observed spherulites was measured.

[0042] 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 the sample in a sample pan was held at 25°C for 3 minutes in a nitrogen atmosphere, and then cooled to -40°C at a cooling rate of 50°C / min. Then, after holding at -40°C for 3 minutes, the sample was heated from -40°C to 200°C at a heating rate of 10°C / min. The melting enthalpy ΔH (J / g) of the sample was determined 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 enthalpy of fusion of the fully crystalline propylene-based resin, and φ is the weight fraction of the propylene-based resin. Here, the enthalpy of fusion of the fully crystalline propylene-based resin was taken as 207 J / g.

[0043] 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 diffractometer (SmartLab manufactured by Rigaku Corporation). The sample was placed in a glass sample holder with a depth of 0.2 mm, and the measurement was 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: 200 mA · X-ray source: Cu-Kα ray (1.5418 Å), · Optical system: Converging method · Incident slit 1 / 3 degree, longitudinal 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 degree · Scan speed: 5 degrees / min · Detector: HyPix-3000

[0044] 4. Evaluation of the surface bleed amount 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 in 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 it was 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 introduced to calculate the surface bleed amount of the lubricating liquid (Component B) per 1 g of the resin composition, and the surface bleed rate represented by the following formula (1) was determined. Surface bleed rate (%) = B 60 / B 0 ×100 (1) B 0: Amount (parts by mass) of the lubricating fluid (Component B) in 1 part by mass of the resin composition at the start of storage B 60 : Amount (parts by mass) of the lubricating fluid (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

[0045] The following materials were used. <Propylene-based resin (Component A)> Propylene-based resin A: Random polypropylene (propylene:ethylene = 96:4 (mol)), PC630A manufactured by Sun Allomer Co., Ltd. Propylene-based resin B: Homopolypropylene, PM600A manufactured by Sun Allomer Co., Ltd.

[0046] <Lubricating fluid (Component B)> Medium-chain fatty acid triglyceride (MCT) Water contact angle: 81° Viscosity: 24 mPa·s Incidentally, the water contact angle for the liquid film was determined by dropping 3 μl of distilled water onto the surface of the 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 DropMaster700 (manufactured by Kyowa Interface Science Co., Ltd.) and measuring the contact angle 10 seconds after dropping. Also, the viscosity of the lubricating fluid was the value measured at 25°C using a B-type viscometer DV2T (manufactured by Brookfield).

[0047] <Nucleating agent (Component C)> Nonitol-based nucleating agent (Millad NX8000E (Milliken Japan))

[0048] <Example 1> Propylene-based resin A was used as the propylene-based resin (component A), medium-chain fatty acid triglyceride (MCT) was used as the lubricant (component B), and Millad NX8000E (Milliken Japan) was used as the crystal nucleating agent (component C). Here, as the crystal nucleating agent (component C), a masterbatch prepared by melt-kneading in advance with the propylene-based resin (component A) to 12% by mass was used. Using a twin-screw kneading extruder (KZW20TW manufactured by Technovel Corporation), melt-kneading was carried out under the condition of a cylinder temperature of 220 °C so that propylene-based resin A:MCT:crystal nucleating agent = 100:25:0.30 (parts by mass). The kneaded product was extruded in a strand shape, air-cooled, and then pelletized to produce a pellet-shaped resin composition having a cylindrical shape with a diameter of 2.5 mm and a length of 3 mm.

[0049] <Example 2> A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that propylene-based resin A:MCT:crystal nucleating agent = 100:25:0.15 (parts by mass).

[0050] <Example 3> A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that propylene-based resin B:MCT:crystal nucleating agent = 100:25:0.30 (parts by mass).

[0051] <Comparative Example 1> A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that propylene-based resin A:MCT:crystal nucleating agent = 100:25:0 (parts by mass).

[0052] <Comparative Example 2> A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that propylene-based resin B:MCT:crystal nucleating agent = 100:25:0 (parts by mass).

[0053] <Comparative Example 3> A resin composition was prepared using a twin-screw kneading extruder under the same conditions as in Example 1, except that propylene-based resin B:MCT:crystal nucleating agent = 100:25:0.15 (parts by mass).

[0054] For the resin compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 3 above, the maximum spherulite diameter, crystallinity, and γ-crystal peak were measured, and the bleeding amount was also measured. 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 is suppressed compared to Comparative Examples 1 to 3. Also, optical micrographs of the resin compositions of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in FIGS. 1 to 6.

[0055]

Table 1

Claims

1. A resin composition comprising a propylene-based resin (Component A), a lubricant (Component B), and a crystal nucleating agent (Component C), wherein the content of Component B is 10 parts by mass or more with respect to 100 parts by mass of Component A, Component A is a random copolymer with an α-olefin, Component B is liquid at 23°C, and when 3 μl of distilled water is dropped onto the surface of the film formed by Component B at 23°C and 50% RH, the contact angle 10 seconds after the drop is 70° or more, The resin composition is in pellet form, 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 the γ-type crystal of the propylene-based resin is observed, The resin composition is characterized in that it is a resin composition for forming a container having a liquid phase of Component B on the surface.

2. The resin composition according to claim 1, wherein the lubricant (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 or 2, wherein the viscosity of the lubricant (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 claims 1 to 3, wherein the crystallinity determined from the melting enthalpy measured by a differential scanning calorimeter (DSC) is 10% or more and 60% or less.

5. 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 ester-based nucleating agents, triaminobenzene derivative-based nucleating agents, carboxylic acid metal salt-based nucleating agents, and xylitol-based nucleating agents.

6. The resin composition according to any one of claims 1 to 5, wherein the surface bleed rate represented by the following formula (1) is 10% or less. Surface bleed rate (%) = B ６０ / B ０ ×100 (1) B ０ : The amount (parts by mass) of the 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 the 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

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