JP2014118453A - Olefin resin foam and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel raw material capable of resolving existing problems such as reduction of workability, environmental property, productivity and the like, increase and complication in the number of processes, and discoloration, change of color and the like, as well as having both of high class feeling and flexibility.SOLUTION: An olefin resin composition by mixing a crystalline olefin thermoplastic elastomer and non-crystalline olefin thermoplastic elastomer in a polyolefin matrix is molded into sheet-like by foam molding by using inert gas with a supercritical state, setting the blending amount of the crystalline olefin thermoplastic elastomer at 3 mass% to 32 mass% based on the whole of the olefin resin composition, and further arranging a cell cross section exposed to outside on at least one of surfaces of the olefin resin foam.

Description

  TECHNICAL FIELD The present invention relates to an olefin resin foam and a method for producing the same, and more particularly, to an olefin resin foam having a high foam and a good feel and a method for producing the same.

  Artificial leather and synthetic leather are materials having a texture similar to natural leather. Since these have advantages such as light weight, water resistance and easy care compared with natural leather, they have been in great demand. In recent years, in order to provide materials with a high-class feeling and soft texture, for example, research on suede-like artificial leather has been actively conducted, but a method for obtaining these suede-like artificial leather The following four methods are mainly proposed.

  The first method is a method of obtaining a suede-like artificial leather by mixing fine particles in a solvent, applying the mixture onto a design surface and drying it.

  As such a method, for example, Patent Document 1 discloses a method in which leather pulverized in an organic solvent is mixed and applied to a design surface, and then dried and buffed to make a suede tone. However, since the method of Patent Document 1 uses an organic solvent, it cannot be said that workability and environmental performance are good.

  Further, Patent Document 2 discloses a method of making a suede tone by screen-printing a paint containing bead pigment or synthetic resin beads after controlling the wettability of the design surface using corona treatment, plasma treatment or the like. Has been. However, in the method of Patent Document 2, not only the installation cost of the apparatus for controlling the wettability is required, but also there is a problem of pot life after the surface treatment, so it is not easy to maintain a certain quality. In addition, when considering the drying process, using an organic solvent is not preferable from the viewpoint of workability and environmental performance, and in the case of an aqueous solvent system, the drying time becomes long, so that productivity decreases from the viewpoint of cycle time. Can be easily imagined.

  Furthermore, Patent Document 3 discloses a method of making a suede tone by applying a polyurethane organic solvent dispersion in which polyamino acid resin powder, silica particles, and the like are mixed. However, since the method of Patent Document 3 uses an organic solvent as in Patent Documents 1 and 2, it is not preferable from the viewpoint of workability and environmental performance.

  The second method is a method of collecting a short fiber, fixing it with a binder, and then buffing to obtain a suede-like artificial leather.

  As such a method, for example, in Patent Document 4, ultrafine fibers made of polyester are spun and then cut shortly, and the ultrafine fibers cut on both sides of a thin fabric are laminated, and for example, fiber crossing is performed using a high-pressure water stream or the like. A method is disclosed in which a body is prepared, impregnated with a polymer elastic body and then brushed by buffing to perform a finishing operation such as dyeing. However, the method of Patent Document 4 has a large number of steps and is complicated, resulting in an increase in cost.

  A third method is a method of obtaining a suede-like artificial leather by forming a core-sheath structure from different materials, forming a fiber sheet, and extracting the sheath material.

  As such a method, for example, in Patent Document 5, a fiber sheet is prepared from a fiber composed of a core material resistant to an alkaline aqueous solution and a sheath material dissolved in the alkaline aqueous solution, and the sheath material is extracted by impregnating the alkaline aqueous solution. Thus, a method of obtaining ultrafine fibers to make an artificial suede is disclosed. When a method of extracting a sheath material after creating a core-sheath structure as in Patent Document 5, the amount of porosity increases and the material has flexibility because the sheath is removed at the same time as the ultrafine fibers remain. Is expected. However, in the method of Patent Document 5, it is necessary to treat the waste liquid, and it is difficult to say that it is an environmentally friendly manufacturing method.

  The fourth method is a method of obtaining a suede-like artificial leather by applying an adhesive to the design surface and then planting short fibers using electrostatic action or the like.

  As such a method, for example, Patent Document 6 discloses a method of making a suede tone by electrostatically flocking a synthetic fiber flock after applying an adhesive on a design surface. However, in the method of Patent Document 6, it is easily imagined that the flocked hair is removed. In addition, since the method of Patent Document 6 uses an adhesive, it cannot be said that the environment is good. Furthermore, a special device for performing flocking is required.

  In addition, the conventional suede-like artificial leather material is often composed of a polyester fiber and a polyurethane elastomer as disclosed in Patent Document 7, for example. However, in the material disclosed in Patent Document 7, both the polyester fiber and the polyurethane elastomer are inferior in light resistance. Therefore, depending on the use environment, white or bright light color may be discolored or discolored.

Japanese Patent No. 2930639 Japanese Patent Laid-Open No. 10-057882 Japanese Patent No. 2966891 JP 2003-286663 A Japanese Patent No. 4644971 Japanese Patent No. 2551814 Special table 2011-523985 gazette

  As described above, materials such as artificial leather and synthetic leather so far have a high-class feeling and flexibility (soft texture), and workability, environmental performance, productivity, etc. are reduced. No technology has yet been proposed that can be produced without increasing and complicating the process and causing weathering problems such as discoloration and discoloration.

  Therefore, the present invention has been made in view of the above circumstances, and it has been possible to solve the conventional problems such as deterioration in workability, environment and productivity, increase and complexity of the number of steps, and discoloration and discoloration. An object of the present invention is to provide a new material that can be eliminated and has both high-class feeling and flexibility.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained an olefin-based resin composition in which a crystalline olefin-based thermoplastic elastomer and an amorphous olefin-based thermoplastic elastomer are mixed with a polyolefin-based resin. By supercritical foaming, a foam having a high foaming ratio and high flexibility can be obtained. By exposing the cell cross section to the outside on at least one surface of the foam, workability, environmental performance and We have found that we can provide a material that combines high-quality and flexibility without causing problems such as a decrease in productivity, an increase and complexity in the number of processes, and fading and discoloration, and the present invention has been completed based on this knowledge. It came to do.

That is, according to the present invention, a supercritical inert gas as a foaming agent is impregnated into an olefin resin composition in which a crystalline olefin thermoplastic elastomer and an amorphous olefin thermoplastic elastomer are mixed in a polyolefin matrix. A sheet-like olefin resin foam having a plurality of cells obtained by extruding while reducing pressure after being formed, wherein the compounding amount of the crystalline olefin thermoplastic elastomer is the olefin resin composition An olefin-based resin foam is provided that is 3% by mass or more and 32% by mass or less based on the total of the above, and has a cell cross section exposed to the outside on at least one surface.
The 10% compression hardness of the olefin resin foam is preferably 0.001 MPa or more and 0.008 MPa or less.
The dynamic friction coefficient of the olefin resin foam is preferably 2.4 or more and 10 or less.
The density of the olefin resin foam is preferably 20 kg / m ³ or more and 70 kg / m ³ or less.
The polyolefin is preferably a polypropylene resin.
Furthermore, the polypropylene resin is preferably homopolypropylene.
The olefin resin foam may further contain a foam nucleating agent in the olefin resin composition.
It is preferable that the inert gas is carbon dioxide.
The total amount of the crystalline olefin-based thermoplastic elastomer and the non-crystalline olefin-based thermoplastic elastomer is preferably 23% by mass or more based on the entire olefin-based resin composition.
The crystalline olefinic thermoplastic elastomer is preferably a block copolymer having linear polyethylene as a hard segment and an ethylene-octene copolymer as a soft segment.
Further, according to the present invention, a sheet-like olefin resin having a plurality of cells in which an olefin resin composition containing a crystalline olefin thermoplastic elastomer and an amorphous olefin thermoplastic elastomer is foamed in a polyolefin matrix. It is a foam, Comprising: The compounding quantity of the said crystalline olefin type thermoplastic elastomer is 3 mass% or more and 32 mass% or less with respect to the whole said olefin resin composition, The surface layer, ie, skin layer, of the said foam is used. An olefin having 10 or more cells in contact with a virtual straight line with a length of 1 mm drawn in the flow direction in a cross section cut with a slicer or the like, and having a cell cross section exposed to the outside on at least one surface -Based resin foam is provided.
Further, according to the present invention, a step of mixing a crystalline olefinic thermoplastic elastomer and an amorphous olefinic thermoplastic elastomer in a polyolefin matrix to obtain an olefinic resin composition, and the molten olefinic resin composition After impregnating the product with an inert gas in a supercritical state as a foaming agent, the olefin-based resin composition impregnated with the inert gas is extruded while decompressing, thereby forming a sheet having a plurality of cells And a step of exposing a cell cross section on the surface side of at least one surface of the sheet-like foam to the outside, and the blending amount of the crystalline olefin-based thermoplastic elastomer is determined based on the olefin-based content. Provided is a method for producing an olefin-based resin foam, which is 3% by mass or more and 32% by mass or less with respect to the entire resin composition.
It is preferable to use a polypropylene resin as the polyolefin.
It is preferable to use homopolypropylene as the polypropylene resin.
A foam nucleating agent may be further added to the olefin resin composition.
Carbon dioxide is preferably used as the inert gas.
The total amount of the crystalline olefinic thermoplastic elastomer and the amorphous olefinic thermoplastic elastomer is preferably 23% by mass or more based on the entire olefinic resin composition.
As the crystalline olefin-based thermoplastic elastomer, it is preferable to use a block copolymer having linear polyethylene as a hard segment and an ethylene-octene copolymer as a soft segment.

  According to the present invention, it is possible to eliminate problems such as deterioration in workability, environmental performance and productivity, increase and complexity of the number of processes, and fading and discoloration, and to provide a high-class feeling and flexibility. It becomes possible to provide a new material that combines.

It is a vertical sectional view showing typically the composition of the olefin system resin foam concerning this form. It is explanatory drawing which shows typically the molecular structure model of the crystalline olefin type thermoplastic elastomer which concerns on the same form. It is a graph which shows an example of the measurement result of differential scanning calorimetry (DSC) to the crystalline elastomer concerning the form. It is a graph which shows an example of the measurement result of differential scanning calorimetry (DSC) to the amorphous elastomer concerning the form. It is explanatory drawing which shows typically the flow of the manufacturing method of the olefin resin foam which concerns on the same form. In order to compare with the foam which concerns on the same form, it is explanatory drawing which shows a cell cross section when a cell diameter (bubble diameter) is coarse. It is explanatory drawing which shows an example of the count method of the bubble number in an Example and a comparative example. It is explanatory drawing which shows an example of the measuring method of the dynamic friction coefficient in an Example and a comparative example. It is the electron micrograph of the cross section which cut | disconnected the surface layer, ie, skin layer, of the foaming sheet of Example 3, and the foaming sheet foamed with the chemical foaming agent using a slicer etc. FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that in the present specification and drawings, components having the same reference numerals have substantially the same structure or function.

The olefin resin foam according to this embodiment will be described in the following order.
DESCRIPTION OF SYMBOLS 1 Structure of olefin resin foam 2 Manufacturing method of olefin resin foam 3 Effect of olefin resin foam 4 Use of olefin resin foam

≪Configuration of olefin resin foam≫
Here, the structure of the olefin resin foam according to this embodiment, the foaming method of the olefin resin foam, the composition of the olefin resin composition, and the physical properties of the olefin resin foam will be described in this order.

<Structure of olefin resin foam>
First, the structure of the olefin resin foam according to this embodiment will be described with reference to FIG. FIG. 1 is a vertical sectional view schematically showing the configuration of the olefin resin foam according to the present embodiment.

  As shown in FIG. 1, an olefin resin foam (hereinafter simply referred to as “foam”) 100 according to the present embodiment includes a crystalline olefin thermoplastic elastomer (hereinafter referred to as “crystalline elastomer” in a polyolefin matrix. And an amorphous olefin-based thermoplastic elastomer (hereinafter referred to as “non-crystalline elastomer”). The foam 100 has a plurality of cells (bubbles) 111 inside. Further, the foam 100 has a cell cross section 120 exposed to the outside on at least one surface thereof (in FIG. 1, the upper surface or the lower surface of the foam 100).

(Foam 100)
〔shape〕
As will be described later, the foam 100 is formed into a sheet by foam molding using an inert gas in a supercritical state. The thickness of the sheet is not particularly limited. For example, when the foam 100 is used for artificial leather or synthetic leather, the thickness may be about 0.3 mm to 2.0 mm.

[Foaming method]
The foam 100 is obtained by molding the olefin resin composition 110 into a sheet by foam molding using an inert gas in a supercritical state. More specifically, a sheet-like foam 100 is obtained by impregnating a molten olefin resin composition 110 with an inert gas in a supercritical state as a foaming agent and then performing extrusion molding while reducing the pressure. Can do. Details of the foaming method, particularly supercritical conditions, types of inert gas, extrusion molding method, and the like will be described later.

(Olefin resin composition 110)
The olefinic resin composition 110 is a mixture of resins containing (mixed) a crystalline olefinic thermoplastic elastomer (crystalline elastomer) and an amorphous olefinic thermoplastic elastomer in a polyolefin matrix. Thus, by adding an elastomer component having rubber-like elasticity to the polyolefin matrix, the foamed body 100 obtained by foaming these mixed resins can have flexibility and good touch. However, if the elastomer component added to the polyolefin matrix is only an amorphous elastomer, bubbles due to the inert gas impregnated in the resin mixture as a foaming agent immediately escape to the outside, and a high expansion ratio (generally 15 times or more), that is, a low-density foam cannot be obtained.

  Therefore, in this embodiment, by adding an appropriate amount of not only a non-crystalline elastomer but also a crystalline elastomer to the polyolefin matrix, it is difficult for air bubbles to escape from the olefin-based resin composition 110, and foaming with a high expansion ratio is performed. I'm getting a body. In other words, the bubble retention ability of the olefin resin composition 110 can be improved by blending the crystalline elastomer. As described in detail later, it is difficult to remove bubbles by blending the crystalline elastomer. However, the crystalline elastomer exhibits a behavior in which the viscosity rapidly increases as the temperature decreases. This is to prevent the bubbles of the inert gas impregnated in the resin composition 110 from leaking outside. Hereinafter, these details are demonstrated in order of a polyolefin matrix, a crystalline olefin type thermoplastic elastomer, and an amorphous olefin type thermoplastic elastomer.

[Polyolefin matrix]
The polyolefin matrix is a component that becomes a matrix resin in the olefin resin composition 110. The polymer used as the polyolefin matrix is not particularly limited, and examples of the polymer include polypropylene resin, polyethylene, polymethylpentene, propylene-ethylene copolymer, (meth) acrylic polymer and ethylene ionomer. It is done.

  The main component of the polyolefin matrix used here is preferably a melting temperature of 150 ° C. or higher and an MFR of 230 ° C. and 2.16 kgf as defined in JIS-K7210 of 5 g / 10 min or less, and 3 g / 10 It is more preferable that it is less than or equal to 1 minute, and it is even more preferable that it is 1 g / 10 minutes or less. On the other hand, the melting temperature is preferably 180 ° C. or lower.

  As a main component of the polyolefin matrix in this embodiment, it is preferable to use a polypropylene resin. The “polypropylene-based resin” referred to here is a polymer in which the main component monomer is propylene, and in this embodiment, any of homopolypropylene, random polypropylene, and block polypropylene may be used. If the polyolefin is polyethylene, there is a possibility that the polyolefin resin composition 110 cannot be foamed at a high expansion ratio (specifically, the expansion ratio is a low ratio of less than 15). One reason for this is that the ease of bubble removal by the inert gas impregnated as a foaming agent differs depending on the glass transition temperature (Tg) of the resin to be foamed. For example, Tg of polypropylene is generally −10 ° C., Tg of polyethylene is around −70 to −100 ° C., and a polypropylene resin having a higher glass transition temperature has a higher ability to retain bubbles than polyethylene. It is. Considering the reasons as described above, the total amount of the polyolefin matrix is more preferably a polypropylene resin. The main component of the polyolefin matrix means a component that occupies the largest proportion (mass basis) of the polyolefin matrix.

  The crystallization rate of the polypropylene resin used as the polyolefin matrix is preferably 30 to 100%, more preferably 30 to 80%, and still more preferably 30 to 70%. By setting it as the said range, it is easy to cool and solidify at the time of foam molding, and the foam 100 which has the fine cell 111 can be obtained. The crystallization rate is calculated with reference to the method for measuring the transition temperature of JIS-K7121 plastic. A sample that has been previously melted at 200 ° C. and cooled at a cooling rate of 10 ° C./min is melted at a temperature increase of 10 ° C./min to obtain melting energy. As a comparative material, a homopolypropylene resin having an MFR of 40 g / 10 min or more evaluated at 230 ° C. and 2.16 kgf as defined in JIS-K7210 was measured in the same manner, and the degree of crystallinity at the melting energy was 100%. Calculate the crystallinity of the sample to be evaluated. Homopolypropylene having an MFR of 40 g / 10 min or more is determined to be saturate because the melting energy is substantially constant, and a material of MFR 40 or more is used as a comparative material.

  Moreover, 90-135 degreeC is suitable for the crystallization temperature (Tc) of polypropylene resin, 95-135 degreeC is more suitable, and 100-135 degreeC is still more suitable. By setting it as the said range, it is easy to cool and solidify at the time of foam molding, and the foam of a fine cell can be obtained. The crystallization temperature is measured according to JIS-K7121.

  In this embodiment, it is preferable to add a high melt tension polypropylene resin to the main component polypropylene resin. As the high melt tension polypropylene resin, one having a melt tension at 200 ° C. of 5 to 50 cN is suitable. The melting temperature of the high melt tension polypropylene resin is preferably in the range of ± 10 ° C. with respect to the melting temperature of the main component polypropylene resin, and preferably ± 20 ° C. with respect to the crystallization temperature. If the melting temperature is out of the above range, poor dispersion may occur when kneading a plurality of materials, and if the crystal temperature is out of the above range, the temperature at which the molten resin in which bubbles grow due to foaming is cooled and solidified. May become non-uniform and a fine cell diameter may not be obtained. The melting temperature and crystallization temperature are calculated with reference to JIS-K7121. Commercially available products can be used as the high melt tension polypropylene-based resin, and specific examples include “HMS-PP” manufactured by Sun Allomer, “New Former” manufactured by Nippon Polypro. The blending ratio of the high melt tension polypropylene resin is preferably 1/5 to 1/4 in terms of mass ratio with respect to the main component polypropylene resin. By using a polypropylene resin exhibiting a high melt tension, the strain hardening property of the olefin resin composition 110 is increased, coalescence of bubbles during molding is suppressed, and a fine foam of the cell 111 is obtained.

  Further, the polypropylene resin used as the polyolefin matrix may be any of homopolypropylene, random polypropylene, and block polypropylene as described above. However, from the viewpoint of increasing the number of fine cells 111 (bubbles having a small diameter), the polypropylene resin is preferably homopolypropylene. The reason for this will be described below.

  The higher the crystallization temperature of the olefin resin composition 110 to be foamed, the finer the cells 111 formed in the foam 100 (the bubble diameter is smaller). This is because the higher the crystallization temperature of the olefin resin composition 110, the shorter the time from the exit of the molding machine used for foam molding to the solidification of the olefin resin composition 110, and the impregnation in the resin mixture. This is because bubble growth of the active gas is suppressed. Here, the crystallization temperature is about 115 ° C. for homopolypropylene, but about 100 ° C. for random polypropylene, so that the cell 111 is finer (the bubble diameter is smaller) in homopolypropylene. Is preferred. In addition, the temperature of the olefin resin composition 110 at the outlet of the molding machine is about 190 ° C. The homopolypropylene represented by the following structural formula (1) has high crystallinity, whereas the random polypropylene represented by the following structural formula (2) includes the following structure (3) that inhibits crystallinity. Therefore, homopolypropylene is preferred from the viewpoint of preventing the inert gas bubbles from escaping outside.

(Chemical formula 1)
_{- (C (CH 3) -C} ) n - (1)
(Chemical formula 2)
_{- (C (CH 3) -C} ) n - (C-C) m - (2)
(Chemical formula 3)
− (C−C) _m − (3)

  The content of the polyolefin matrix as described above is preferably 30 parts by mass or more and 77 parts by mass or less, and 40 parts by mass or more and 77 parts by mass when the entire polyolefin-based resin composition 110 is 100 parts by mass. It is more preferable that the content is 45 parts by mass or more and 77 parts by mass or less. Further, the content of the polypropylene resin is preferably 30 parts by mass or more and 77 parts by mass or less, and preferably 35 parts by mass or more and 77 parts by mass or less when the entire polyolefin matrix is 100 parts by mass. More preferred is 70 parts by mass or more and 77 parts by mass or less.

[Crystalline Olefin Thermoplastic Elastomer]
Next, the crystalline olefin thermoplastic elastomer (crystalline elastomer) according to this embodiment will be described with reference to FIG. FIG. 2 is an explanatory view schematically showing a molecular structure model of the crystalline olefin-based thermoplastic elastomer according to the present embodiment.

As shown in FIG. 2, the crystalline elastomer according to this embodiment to be mixed in the olefin resin composition 110 includes a hard block of linear low density polyethylene (LLDPE) and an ethylene-octene copolymer (EOR). It is an olefin block copolymer composed of a soft soft block. The hard block of LLDPE is a block having a high melting point, and has a role of a crosslinking point below the crystallization temperature of the crystalline elastomer. The density of LLDPE is generally 900 to 940 kg / m ³ . On the other hand, the soft block of EOR is an amorphous block with a large comonomer content and has a role of showing the properties of rubber. This crystalline elastomer is a material that exhibits rubber-like properties when LLDPE acts as a physical cross-linking point below the crystallization temperature, and melts and can be processed above the melting temperature.

  By containing such a crystalline elastomer in the olefin-based resin composition 110, as described above, the effect of enhancing the bubble retention ability of the olefin-based resin composition 110 and making it difficult for bubbles to escape from the resin mixture. As a result, a foam 100 with a high expansion ratio can be obtained.

  Further, the melt flow rate (MFR) of the crystalline elastomer according to this embodiment is not particularly limited, but the viscosity as the composition of the olefin resin composition is from the viewpoint of obtaining a foam having an extrusion foaming property and a high expansion ratio. Since the higher one is preferable, the MFR at 190 ° C. and 2.16 kg specified in JISK6922-2 is preferably 1.0 g / 10 min or less, and more preferably 0.5 g / 10 min or less. . On the other hand, the lower limit value of the MFR is not particularly specified, but may be approximately 0.01 g / 10 minutes or more.

  Furthermore, the melting temperature of the crystalline elastomer according to this embodiment is not particularly limited, but it must be below the melting point of the main polyolefin from kneading with the polyolefin matrix in the olefin resin composition preparation step described later, and differential scanning calorimetry It is preferable that the melting temperature measured by (DSC) is 100-180 degreeC, and it is more preferable that it is 100-160 degreeC.

  Further, the crystallization temperature of the crystalline elastomer according to the present embodiment is not particularly limited, but from the viewpoint of quickly crystallizing the olefin resin composition 110 by cooling in the extrusion foaming process, crystals measured according to JIS-K7121 The conversion temperature is preferably 90 to 135 ° C, more preferably 90 to 125 ° C.

[Amorphous olefin-based thermoplastic elastomer]
Since the non-crystalline olefinic thermoplastic elastomer (noncrystalline elastomer) according to the present embodiment mixed in the olefinic resin composition 110 does not have a crystallization temperature, the crystalline elastomer at or below the crystallization temperature seems to have. It is a polymer having no physical cross-linking point (hard block). Such an amorphous elastomer is not particularly limited as long as it has a high viscosity and rubbery properties. For example, styrene elastomer, ethylene-propylene-diene terpolymer, ethylene-propylene copolymer And other thermoplastic elastomers.

  By containing these non-crystalline elastomers in the olefin resin composition 110, the effect of imparting flexibility to the foam 100 is obtained as described above.

  The weight average molecular weight of the amorphous elastomer according to this embodiment is not particularly limited, but it is preferable that the viscosity of the olefin-based resin composition is high from the viewpoint of obtaining a foam having an extrusion foaming property and a high expansion ratio. Therefore, it is preferably 250,000 or more, and more preferably 300,000 or more. On the other hand, the upper limit value of the weight average molecular weight is not particularly specified, but may be approximately 600,000 or less. In addition, let the weight average molecular weight here be the value calculated | required in polystyrene conversion using the high temperature gel permeation chromatograph.

[Method for distinguishing between crystalline elastomer and amorphous elastomer]
Next, a method for discriminating between the crystalline elastomer and the amorphous elastomer according to this embodiment will be described with reference to FIGS. FIG. 3 is a graph showing an example of the results of differential scanning calorimetry (DSC) for the crystalline elastomer according to this embodiment, and FIG. 4 is the differential scanning calorimetry (DSC) for the amorphous elastomer according to this embodiment. It is a graph which shows an example of a measurement result.

  The crystalline elastomer and the amorphous elastomer according to this embodiment can be distinguished by confirming the presence or absence of a peak in DSC measurement. Specifically, in the DSC measurement, those in which a peak due to endotherm and heat generation of the crystalline component appears can be determined as a crystalline elastomer, and those in which the peak does not appear can be determined as an amorphous elastomer. Hereinafter, the discrimination method of both will be described in more detail while showing an example of a DSC measurement result for discriminating between a crystalline elastomer and an amorphous elastomer.

First, DSC of the crystalline elastomer was performed under the following conditions.
Sample mass: 12.633 mg
Temperature rising condition: 10 ° C./min (25 ° C. to 200 ° C.)
Temperature drop condition: 5 ° C / min (200-0 ° C)

  As shown in FIG. 3, when the crystalline elastomer is heated under the above temperature rising condition, the crystalline component of the crystalline elastomer {in this embodiment, linear low density polyethylene (LLDPE)} is melted by endotherm. At this time, a peak accompanying the endotherm of the crystal component (downward peak surrounded by a dotted line in FIG. 3) appears. Next, when the crystalline elastomer is cooled under the above temperature-decreasing conditions, the crystalline component of the melted crystalline elastomer is recrystallized due to heat generation, resulting in a change in viscosity (the viscosity increases rapidly). At this time, a peak accompanying the heat generation of the crystal component (an upward peak surrounded by a dotted line in FIG. 3) appears.

  As described above, in the crystalline elastomer, a peak due to endothermic and exothermic appearance of the crystal component appears. In addition, since the viscosity of the crystalline elastomer suddenly increases near the crystallization temperature when cooled, bubbles that grow and grow may escape to the outside in the olefin resin composition 110 in which the crystalline elastomer is mixed. It is suppressed and it becomes easy to form the cell 111 stably.

Next, DSC of the amorphous elastomer was performed under the following conditions.
Sample mass: 12.818 mg
Temperature rising condition: 10 ° C./min (25 ° C. to 200 ° C.)
Temperature drop condition: 5 ° C / min (200-0 ° C)

  As shown in FIG. 4, when the amorphous elastomer is heated under the above temperature rising condition, the crystalline elastomer does not exist in the amorphous elastomer, so that the crystalline component does not melt due to endotherm. Therefore, a peak due to endotherm that can be confirmed with a crystalline elastomer does not appear. Next, when the amorphous elastomer is cooled under the above temperature-decreasing conditions, the elastomer does not melt at the time of heating, so there is no sudden viscosity change at the time of cooling, and there is a peak due to heat generation that can be confirmed with the crystalline elastomer. It does not appear (see the part surrounded by the dotted line in FIG. 4).

  Thus, in an amorphous elastomer, since there is no crystal component, the peak accompanying the endotherm and exotherm does not appear. In addition, since an amorphous elastomer does not rapidly increase in viscosity when cooled, the elastomer component is only an amorphous elastomer, and foams and grows in an olefin resin composition in which no crystalline elastomer is mixed. Since the bubbles easily escape to the outside, the cells 111 are hardly formed stably. Moreover, in the olefin resin composition in which the crystalline elastomer is not mixed, the bubbles may be broken and the foaming ratio of the foam 100 may be lowered.

[Total amount of crystalline elastomer and non-crystalline elastomer]
The total amount of the crystalline elastomer and the amorphous elastomer described above is preferably 23% by mass or more, and more preferably 35% by mass or more, based on the entire olefin resin composition 110. Preferably, it is 45 mass% or more. The softness | flexibility of the foam 100 can be improved by the total compounding quantity of a crystalline elastomer and an amorphous elastomer being 23 mass% or more.

  On the other hand, if the amount of the elastomer component (crystalline elastomer and amorphous elastomer) is too large, the inert gas bubbles impregnated in the olefin-based resin composition 110 may be easily removed. The total amount of the amorphous elastomer is preferably 55% by mass or less.

[Amount of crystalline elastomer]
Moreover, the compounding quantity of a crystalline elastomer shall be 3 mass% or more and 32 mass% or less with respect to the whole olefin resin composition 110. FIG. When the blending amount of the crystalline elastomer is less than 3% by mass, the effect of addition, that is, the effect of stably forming the cell 111 by making it difficult to escape the bubbles is not sufficient. On the other hand, since it is preferable that the viscosity of the composition of the olefin-based resin composition is high from the viewpoint of obtaining a foam having an extrusion foaming property and a high expansion ratio, the blending amount of the crystalline elastomer is set to 32% by mass or less. In order to further improve the effect of adding the crystalline elastomer, the amount of the crystalline elastomer is preferably 5% by mass or more and 32% by mass or less, and preferably 10% by mass or more and 32% by mass or less. More preferred.

[Foaming nucleating agent]
The olefin-based resin composition 110 according to this embodiment may further contain a foam nucleating agent in addition to the components described above. The foaming nucleating agent that can be used in the present embodiment is not particularly limited. For example, talc, silica, zeolite, magnesium oxide, barium sulfate, calcium oxide, magnesium hydroxide, titanium oxide, alumina, mica, zinc oxide, calcium carbonate, etc. Is mentioned.

  By adding such a foam nucleating agent to the olefin-based resin composition 110, the size (bubble diameter) of the obtained cell 111 can be easily and arbitrarily adjusted. This is because if the foam nucleating agent is contained, the foam nucleating agent serves as a starting point for foaming with an inert gas, and therefore, fine cells 111 (bubbles having a small diameter) can be stably formed. On the other hand, if the foam nucleating agent is not contained, foaming occurs simultaneously and frequently in any place. Therefore, if there is a place where foaming occurs intensively, the bubbles are coalesced in the place and the coarse cell (diameter Large bubbles) may be formed.

  Although content of a foam nucleating agent is not specifically limited, For example, it is preferable that it is 3 mass% or more and 10 mass% or less with respect to the whole olefin resin composition 110, and it is 3 mass% or more and 5 mass% or less. More preferably. If the content of the foam nucleating agent is less than 3% by mass, the effect of addition, that is, the effect that the bubble diameter can be easily and arbitrarily adjusted may not be sufficient, and the content of the foaming nucleating agent is 10% by mass. If it exceeds 1, the flexibility of the resulting foam may be impaired, such being undesirable.

[Other additives]
In addition, the olefin-based resin composition 110 contains other additives such as a crystal nucleating agent, a pigment, an antioxidant, and a lubricant as necessary, as long as the effects of the present invention are not impaired. Also good.

[Crystal nucleating agent]
The olefin resin composition 110 according to the present embodiment may further contain a crystal nucleating agent as necessary. Although it does not specifically limit as a crystal nucleating agent which can be used with this form, For example, bis (p-methyl benzylidene) sorbitol, dibenzylidene sorbitol, bis (p-ethyl benzylidene) sorbitol, hydroxy (t-butylbenzoic acid) aluminum, Sodium bis (4-tbutyl-phenyl) phosphate, methylene bis (2,4-ditbutyl-phenyl) phosphate sodium salt, potassium rosinate, magnesium rosinate, N, N′-dicyclohexyl-2,6-naphthalene And carboxamide, N, N ′, N ″ -tris (2-methylcyclohexane-1-yl) propane-1,2,3-triylcarboxamide, and the like. These commercially available nucleating agents are used. As a commercial product, Gel Nippon NA11 such as STAB of and ADEKA Corporation, and the like.

  By adding such a crystal nucleating agent to the olefin-based resin composition 110, the crystallization temperature of the polyolefin matrix can be shifted to the high temperature side, and a finer foam can be obtained.

  The content of the crystal nucleating agent is not particularly limited. For example, the content of the crystal nucleating agent is preferably 0.01% by mass or more and 0.5% by mass or less, based on the entire olefin resin composition 110, and 0.01% by mass. More preferably, it is 0.2 mass% or less. If the content of the crystal nucleating agent is less than 0.01% by mass, the effect of addition, that is, the effect of obtaining a finer foamed foam may not be sufficient, and the content of the foaming nucleating agent is 0. If it exceeds 0.5 mass%, the effect due to the addition amount hardly changes, so it is sufficient to contain 0.5 mass%.

[Pigment]
The olefin resin composition 110 according to the present embodiment may further contain a pigment as necessary. Examples of pigments that can be used in this embodiment include carbon black, titanium oxide, isoindoline yellow, monoazo red, gamma quinacridone, copper phthalocyanine blue, and the type and content unless the foaming ratio of the foam 100 is reduced. There are no particular restrictions.

〔Antioxidant〕
The olefin resin composition 110 according to the present embodiment may further contain an antioxidant as necessary. Examples of the antioxidant that can be used in this embodiment include a phenol-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, and the like, and are not particularly limited as long as the expansion ratio of the foam 100 is not lowered. . Commercially available products may be used as these antioxidants. Examples of commercially available products include Adeka Stab AO-60 manufactured by ADEKA Corporation and Irganox 1010 manufactured by BASF Japan Co., Ltd. as phenolic antioxidants. Can be mentioned.

  Although content of antioxidant is not specifically limited, The general addition amount is 0.1-0.2 mass part.

(Cell 111)
Referring to FIG. 1 again, the foam 100 has a plurality of cells 111 therein. The “cell” referred to here is a closed cell or open cell (void portion) formed by leaving bubbles of an inert gas impregnated as a foaming agent when the olefin resin composition is foamed. As will be described later, the cell 111 is formed by impregnating an olefin resin composition with an inert gas in a supercritical state as a foaming agent and then reducing the pressure.

[Number of cells 111]
In addition, the number of cells 111 can be evaluated using the following indices.

  In the cross section obtained by cutting the surface layer, that is, the skin layer of the foam 100 using a slicer or the like, the number of the cells 111 that contact the imaginary straight line with a length of 1 mm drawn in the flow direction of the foam 100 is 10 or more. Is preferable, more preferably 16 or more, and still more preferably 19 or more. That the number of the cells 111 is within this range means that the cells 111 are finely formed in the foam 100. Therefore, by setting the number of the cells 111 within this range, the friction coefficient in the cell cross section 120 is increased, so that it is possible to realize a good feeling and a high-class feeling having a moist feeling. The upper limit value of the number of cells 111 is not particularly specified, but may be approximately 30 or less.

  The number of cells 111 can be measured as follows. First, the surface layer, that is, the skin layer of the foam 100 is cut using a slicer or the like. Next, the cell cross section of the foam 100 after cutting is photographed using an electron microscope, the contrast of this photographed image is adjusted, and the horizontal direction of the foam 100 with respect to the sharpest image is adjusted. The number of cells 111 can be measured by drawing a straight line of 1 mm (corresponding to the “virtual straight line”) and counting the number of cells in contact with the straight line.

(Cell cross section 120)
As shown in FIG. 1, the foam 100 has a sheet-like shape, and has a cell cross section 120 exposed to the outside on at least one surface thereof. The “cell cross section” as used herein refers to a portion where the inner wall of the cell 111 inside the foam 100 is exposed to the outside by cutting, cutting or peeling the surface layer of at least one surface of the foam 100. Thus, it refers to the recess 121 derived from the cell 111 formed on at least one surface of the foam 100.

  In the cell cross section 120, the wall surface of the recess 121 (a part of the surface that was the inner wall of the cell 111) has a role corresponding to a raised portion in a so-called suede artificial leather or synthetic leather. In the foam 100 according to the present embodiment, a large number of fine (small bubble diameter) cells 111 are formed at a high expansion ratio. Therefore, the number of wall surfaces of the recesses 121 in the cell cross section 120 (suede-like artificial leather or synthetic leather) Etc.) (corresponding to the number of hairs in the etc.). Therefore, according to the cell cross section 120 according to the present embodiment, a moist feeling (moist feeling) and a high-class feeling can be given to the surface of the foam 100.

  In this embodiment, the case where the cell cross section 120 is formed on one surface of the foam 100 is described as an example, but the cell cross section 120 may be formed on both surfaces of the foam 100.

<Physical properties of olefin resin foam>
Next, the physical properties of the foam 100 according to this embodiment having the above-described structure will be described. Below, it describes in order of 10% compression hardness of the foam 100, a dynamic friction coefficient, and a density.

(10% compression hardness)
In this embodiment, the 10% compression hardness is an index representing the flexibility of the foam 100. The smaller the 10% compression hardness, the higher the flexibility of the foam 100. This 10% compression hardness is a value measured according to JIS-K6767. Specifically, the compression hardness of the present embodiment is calculated from the load when the test piece of the foam 100 is continuously compressed at a predetermined compression speed and compressed by 10% under a predetermined condition. When the value of the 10% compression hardness is large, the foam 100 approaches a phenomenon of “bottom”, and the flexibility becomes low (hard).

[Preferred range]
In this embodiment, in particular, the 10% compression hardness of the foam 100 is preferably 0.008 MPa or less, more preferably 0.007 MPa or less, and further preferably 0.006 MPa or less. By setting the 10% compression hardness within the above range, the foam 100 has excellent flexibility and good texture. The 10% compression hardness is preferably as low as possible, and the lower limit is not particularly defined.

〔Measuring method〕
The 10% compression hardness is measured, for example, as follows. With reference to JIS-K6767, a static testing machine (trade name: Autograph AG-X, Inc.) in a measurement room controlled at an environmental temperature of 23 ± 5 ° C. and an environmental humidity of 50 (+20, −10)% The compressive strength of the foam 100 is evaluated using Shimadzu Corporation. The test piece is 50 mm × 50 mm, the foam is continuously compressed at a compression rate of 1 mm / min, and the test force (load) when 10% compression is performed is read with a load cell, and the compression hardness (compression stress) is determined from the test force. Can be calculated. The number of n is 3, for example, and an average value of three measurements is used as 10% compression hardness.

(Dynamic friction coefficient)
In this embodiment, the coefficient of dynamic friction is an index representing the feel (particularly moist) or high-quality feeling of the surface of the foam 100, and the dynamic friction of the surface of the foam 100 (the surface on the side where the cell cross section 120 is formed). It can be evaluated that the larger the coefficient, the better the touch and the higher quality. This dynamic friction coefficient is a value measured with reference to JIS-K7312.

[Preferred range]
In this embodiment, in particular, the dynamic friction coefficient of the surface of the foam 100 on which the cell cross section 120 is formed is preferably 2.4 or more, more preferably 5.0 or more, and 8.0. It is still more preferable that it is above. By setting the dynamic friction coefficient within the above range, it is possible to give the foam 100 an excellent feel (particularly a moist feel) and a high-quality appearance. In addition, although it does not prescribe | regulate especially about the upper limit of a dynamic friction coefficient, what is necessary is just to generally be 10 or less.

〔Measuring method〕
The dynamic friction coefficient is measured as follows, for example. A test piece having a size of 100 mm × 200 mm was prepared such that the thickness was 1 mm and the flow direction of the foam 100 was orthogonal to the longitudinal direction of the test piece. Next, a test piece for measuring the dynamic friction coefficient was attached to the sliding piece with an adhesive tape, and the same environment was measured three times at a test speed of 150 mm / min with a test environment of 23 ° C. and 50% RH with reference to JIS-K7312. Let the average value be the dynamic friction coefficient of the foam 100.

(density)
In this embodiment, the density is an index that represents the expansion ratio of the foam 100. The smaller the density of the foam 100, the higher the foam 100 can be evaluated. The density of the foam 100 is a value measured by an underwater substitution method based on JIS-K7112.

[Preferred range]
In this embodiment, the density of the foam 100 is preferably 20 kg / m ³ or more and 70 kg / m ³ or less, more preferably 30 kg / m ³ or more and 70 kg / m ³ or less, and 35 kg / m ³ or more and 70 kg. / M ³ or less is more preferable. By setting the density in the above range, the foam 100 can be highly foamed (expanding ratio is generally 15 times or more), and the foam 100 can be provided with flexibility, excellent feel, and luxury.

〔Measuring method〕
The density of the foam 100 can be determined by, for example, an underwater substitution method using an electronic hydrometer MD-200S manufactured by Mirage Trading Co., Ltd. according to JIS-K7112. Or you may measure the density of the foam 100 according to JIS-K7222.

≪Method for producing olefin resin foam≫
While the configuration of the foam 100 according to the present embodiment has been described in detail above, a method for manufacturing the foam 100 having the above-described configuration will be described with reference to FIG. Drawing 5 is an explanatory view showing typically the flow of the manufacturing method of the olefin system resin foam concerning this form.

  The manufacturing method of foam 100 according to the present embodiment mainly includes an olefin-based resin composition preparation step, a foam molding step, and a cell cross-section forming step. These three steps are only divided into three for convenience, and do not need to be strictly divided into three. Hereinafter, details of processing in each step will be described in order.

<Olefin resin composition preparation process>
In the olefin-based resin composition preparation step, a crystalline olefin-based thermoplastic elastomer and an amorphous olefin-based thermoplastic elastomer are mixed in a polyolefin matrix, and the olefin-based resin composition 110 (see FIG. 5A) is mixed. It is a process to obtain. More specifically, each component of the olefin resin composition 110 is charged into a resin mixing machine such as a single screw extruder, a twin screw extruder, a kneader, or a Banbury mixer, and the olefin resin composition 110 is obtained by melt mixing. It is preferable to use a pelletized olefin resin composition 110.

(Components of Olefin Resin Composition 110)
Here, in this embodiment, as described above, from the viewpoint of forming the fine (small cell diameter) cell 111, it is preferable to use a polypropylene resin as the polyolefin, and further, a homopolypropylene is used as the polypropylene resin. It is preferable. From the viewpoint of making it difficult for air bubbles to escape from the olefin-based resin composition 110, the crystalline olefin-based thermoplastic elastomer has linear polyethylene as a hard segment and an ethylene-octene copolymer as a soft segment. It is preferable to use a block copolymer. Furthermore, from the viewpoint of forming fine (small cell diameter) cells 111, it is preferable to further add a foam nucleating agent to the olefin-based resin composition 110.

(Amount of elastomer component)
In this embodiment, the total amount of the crystalline olefin thermoplastic elastomer and the amorphous olefin thermoplastic elastomer is changed to the olefin resin composition 110 in order to obtain flexibility, good touch, high quality, and the like. It is preferable to set it as 23 mass% or more with respect to the whole. Furthermore, the compounding quantity of a crystalline olefin type thermoplastic elastomer shall be 3 to 32 mass% with respect to the whole olefin resin composition.

  Since the other points are the same as those described in the configuration of the foam 100, detailed description thereof is omitted.

<Foam molding process>
In the foam molding step, the olefin resin composition 110 obtained in the above-described olefin resin composition preparation step was melt plasticized using an extruder, and then impregnated with a supercritical inert gas as a foaming agent. After (FIG. 5 (b), where the state of impregnation with the foaming agent is indicated by a broken line, it indicates that the foaming agent is uniformly dissolved in the olefin-based resin composition 110), and this inert gas is impregnated. This is a step of obtaining a sheet-like foam having a plurality of cells (see FIG. 5C) by extruding the olefin-based resin composition while reducing the pressure.

(Foaming method)
Generally, as a foaming method of the resin composition, there are a method using a chemical foaming agent, water vapor foaming, supercritical foaming, etc., but in order to form finer cells (reduce the bubble diameter), in this embodiment, Perform foam molding using supercritical foaming. Hereinafter, this foam molding process will be described in more detail.

(Foaming agent)
In this step, first, the molten olefin resin composition 110 is impregnated with a supercritical inert gas as a foaming agent. As the inert gas used here, a gas such as carbon dioxide and nitrogen can be used, and among these, carbon dioxide is preferably used. Carbon dioxide is preferred as the blowing agent because nitrogen can impregnate the olefin resin composition 110 in a relatively small amount, whereas carbon dioxide can impregnate the olefin resin composition 110 in a large amount. is there. If the olefin-based resin composition 110 can be impregnated in a large amount with an inert gas that is a foaming agent, the expansion ratio of the olefin-based resin composition 110 can be increased, and thus a foam 100 having a high expansion ratio can be obtained. This is because it can. In addition, since carbon dioxide has a larger molecular size than nitrogen, there is also a reason that it is difficult to escape from the olefin resin composition 110.

(Method of impregnating foaming agent)
As the impregnation method of the foaming agent, for example, after the olefin resin composition 110 is melt plasticized, the pressure is increased by a gas supply device from an injection nozzle provided in the vicinity of the melting zone, and the inert gas is brought into a supercritical state ( The foaming agent is discharged into the extruder and dissolved in the molten olefin resin composition 110. As described above, the inert gas in a supercritical state is introduced into the extruder and dissolved in the molten olefin resin composition 110 so that the blowing agent is dissolved in the olefin resin composition 110. (FIG. 5 (b), however, the state of impregnation with the foaming agent is indicated by a broken line, but indicates that the foaming agent is uniformly dissolved in the olefin resin composition 110.)

(Supercritical conditions)
Here, by using a supercritical inert gas as a foaming agent, the diameter of the cell 111 of the foam 100 can be reduced. As a supercritical condition for reducing the diameter of the cell 111 in this way, Is as follows. When the inert gas is carbon dioxide, the pressure must be 7.3 MPa or higher and the temperature must be 31 ° C. or higher. The pressure is more preferably 8 MPa or more, and further preferably 9 MPa or more. Although the upper limit of the pressure of carbon dioxide is not particularly limited, for example, it is realistic to set it to 20 MPa or less. Although the upper limit of the temperature of carbon dioxide is not particularly limited, for example, a temperature at which the olefin resin composition 110 is not thermally decomposed can be set, for example, 300 ° C. When the inert gas is nitrogen, the supercritical state is secured by setting the pressure to 3.4 MPa or higher and the temperature to −147 ° C. or higher.

(Decompression and extrusion molding)
Next, the foam 100 is obtained by reducing the pressure of the olefin resin composition 110 impregnated with the foaming agent. Introducing an inert gas in a supercritical state to the olefin-based resin composition 110 melted in the extruder, under a predetermined supercritical condition (for example, when the inert gas is carbon dioxide, the temperature is 31 ° C. or higher, In addition, the foam 100 having small and fine cells 111 can be obtained by discharging from the die port, rapidly reducing the pressure to atmospheric pressure, and cooling. For example, when the inert gas is carbon dioxide, the carbon dioxide can maintain a supercritical state by setting the temperature to 31 ° C. or higher and the pressure to 7.3 MPa or higher. And supercritical carbon dioxide are uniformly mixed.

  In addition, in the mixing of the olefin resin composition 110 and the inert gas in the supercritical state, an extruder (tandem type extruder) in which two or more units are connected so as not to be released to the atmosphere and below the above pressure is used. It is preferable to adjust the temperature by elongating the length of the process line for mixing and extruding to lower the temperature of the mixture. The olefin resin composition 110 immediately before foaming preferably has a temperature near the pour point of the composition. By keeping the temperature low, the pressure difference before and after foaming becomes large, a large number of bubble growth nuclei are generated, and the foam 100 having fine cells 111 can be obtained. Moreover, after foaming, the olefin resin composition 110 can be cooled more rapidly and solidified. Therefore, the bubble growth can be stopped at an early stage, and the foam 100 having a small diameter of the cell 111 can be easily obtained.

  The die structure in the extruder is not particularly limited, and examples thereof include a T die and a circular die. Among these, the circular die is suitable because the foamed sheet 100 having a uniform thickness can be obtained. When a circular die is used, a cylindrical foam 100 is obtained, but it can be formed into a sheet by cutting one side. Thus, during extrusion molding, a long sheet-like foam can be continuously formed directly by selecting a T-die or through a cylindrical foam by selecting a circular die. it can.

<Cell cross section formation process>
The cell cross-section forming step is a step of exposing the cell cross-section 120 on the surface side of at least one surface of the sheet-like foam 100 obtained in the foam molding step described above to the outside.

(Method for exposing cell cross section 120)
The method of exposing the cell cross section 120 to the outside is not particularly limited, and examples thereof include a method of cutting, cutting, or peeling the surface layer of at least one surface of the foam 100. By exposing the cell cross section 120 to the outside by such a method, the inner wall of the cell 111 inside the foam 100 is exposed to the outside, and a recess 121 derived from the cell 111 is formed on at least one surface of the foam 100. (For example, FIG. 5D). As described above, the cell cross section 120 can give a moist feeling (moist feeling) and a high-class feeling to the surface of the foam 100.

(Surface forming cell cross section 120)
In this embodiment, the case where the cell cross section 120 is formed on one surface of the foam 100 is described as an example, but the cell cross section 120 may be formed on both surfaces of the foam 100.

<Summary>
The foam 100 which has the structure mentioned above can be obtained by passing through the olefin resin composition preparation process demonstrated above, the foam molding process, and the cell cross-section formation process.

≪Function and effect of olefin resin foam≫
Next, the effect which the foam 100 which concerns on this form which has the structure mentioned above and is obtained by the manufacturing method mentioned above show | plays FIG. 6 is demonstrated. FIG. 6 is an explanatory diagram showing a cell cross section when the cell diameter (bubble diameter) is coarse for comparison with the foam according to the present embodiment.

  The foam 100 according to the present embodiment is a foam having cells 111 obtained by impregnating a foaming agent into a molten olefin resin composition 110 and then reducing the pressure. It uses an inert gas in a state. Unlike the case of using a chemical foaming agent, in this form, the foaming agent becomes an odorless gas by using an inert gas in a supercritical state, which not only causes odors and black foreign substances. In addition, it is possible to obtain a foam 100 with a high expansion ratio, a small size (cell diameter) of the cell 111 and a fine texture. Therefore, the obtained foam 100 is a flexible foam having a high friction coefficient, a good feel, and a high-class feeling.

(Effects of having fine cells)
Here, the effect which the foam 100 in this form has by having the fine cell 111 is demonstrated, comparing FIG.5 (c), (d) and FIG.

  As shown in FIGS. 5C and 5D, when the cell 111 is fine (the bubble diameter is small), the concave portion 121 derived from the cell 111 is exposed when the cell cross section 120 is exposed to the outside by cutting, peeling, or the like. Since the number of inner walls is finely increased, the number of hairs compared to the flocking process performed with suede-like artificial leather or the like is increased, and the density of the hairs is also high. Therefore, the coefficient of friction of the surface of the foam 100 on which the cell cross section 120 is formed is increased, giving a moist and good feel and giving a high-quality appearance.

  On the other hand, as shown in FIG. 6, in the foam 500 having a rough cell 511 (having a large bubble diameter), when the cell cross section 520 is exposed to the outside by cutting, peeling, etc., the inner wall of the recess 521 derived from the cell 511 The distribution of the hair becomes sparse, and the number of hairs compared with flocking is small, and the density of the hairs is low. Accordingly, the coefficient of friction on the surface of the foam 500 where the cell cross section 520 is formed is low, the feel is poor, and a high-class feeling is hardly imparted.

(Elements necessary to obtain a high expansion ratio)
As described above, according to the present embodiment, the foam 100 with a high expansion ratio can be obtained. As components necessary for obtaining a foam with a high expansion ratio as described above, the following ( 1-1). Furthermore, the following (1-2) and (1-3) are mentioned as a suitable component in order to obtain the foam of a high foaming ratio. The expansion ratio of the foam is set to a predetermined density of the unfoamed resin composition (for example, 900 kg / m ^{3 in the} examples described later), and the value of the density of the foam after foaming is used. , (Density of unfoamed resin composition / density of foam after foaming). That is, the expansion ratio here is the reciprocal of the ratio of the density after foaming to the density before foaming.
(1-1) Compounding a crystalline elastomer in the olefin-based resin composition 110 (1-2) The blending ratio of the crystalline elastomer is 3% by mass or more to the entire olefin-based resin composition 110 32 (1-3) Use carbon dioxide as a dispersant (inert gas)

(Elements necessary to form fine cells)
As described above, according to the present embodiment, the foam 100 having the fine cells 111 can be obtained. The components necessary for obtaining the foam having the fine cells as described above are as follows: (2-1) and (2-2) are mentioned. Furthermore, the following (2-3)-(2-5) are mentioned as a suitable component for obtaining the foam which has a fine cell.
(2-1) Compounding a crystalline elastomer in the olefin-based resin composition 110 (2-2) Molding the foam 100 by supercritical foaming (2-3) (2-4) Use of homopolypropylene as the polyolefin matrix (2-5) Foaming nuclei in the olefin resin composition 110 Compounding agents

(Elements necessary to obtain a flexible foam)
As described above, according to the present embodiment, the flexible foam 100 can be obtained. As components necessary for obtaining such a flexible foam, the following (3-1) Is mentioned. Furthermore, the following (3-2) is mentioned as a suitable component for obtaining a flexible foam.
(3-1) Blending an elastomer component in the olefin resin composition 110 (3-2) The total blending amount of the crystalline elastomer and the amorphous elastomer is based on the whole olefin resin composition 110. 23 mass% or more

(Other effects)
In addition, the foam 100 according to the present embodiment has the following effects.

  First, the foam 100 has a high surface friction resistance because the cells 111 are fine. Therefore, since the appearance with a good touch and a high-class feeling can be obtained, the foam 100 can be used for applications that require a high-class feeling and texture such as clothing accessories.

  Second, since the foam 100 is formed using a polyolefin-based resin, the foam 100 is more excellent in light resistance than those using a conventional polyester-based resin, so that discoloration or discoloration hardly occurs.

  3rdly, the foam 100 has acquired the form similar to raising by cutting the surface layer etc. by foaming the olefin resin composition 110, and obtaining the cell cross section 120. FIG. Thus, since the foam 100 uses a simple process, it is possible to obtain a high-quality material with a good feel without going through a long process represented by the method of Patent Document 4. . Therefore, the process is shortened, leading to cost reduction.

≪Use of olefin resin foam≫
The use of the foam 100 according to the present embodiment is not particularly limited. For example, it is used for container wrapping such as anti-slip of a tray underlay, a sleeve, and a container skin, sports goods such as a grip for a pad and a racket, a coaster, and a place mat , Interior products such as wallpaper, automotive interior materials such as handles and shift knobs, hats, clothes, bags, footwear, apparel such as insoles, cosmetics such as makeup members and puffs, adhesive plaster and haps, underwear The present invention can be applied to various uses such as medical use such as wrap tape, and general use such as book cover, lamp shade, rain gear, and muffler.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the following examples do not limit the present invention.

≪Sample preparation method≫
First, the preparation method of the sample used for evaluation of a present Example and a comparative example is demonstrated.

<Example 1>
As a polyolefin-based matrix, a total of 100 parts by mass of polypropylene A and polypropylene B mixed so as to have a desired melt tension, 30 parts by mass of thermoplastic elastomer C as an amorphous elastomer, and thermoplastic elastomer as a crystalline elastomer An olefin resin in which 8 parts by mass of D, 8 parts by mass of silica E as a foam nucleating agent, 15 parts by mass of titanium oxide F as a pigment, and 0.2 parts by mass of a phenolic antioxidant H as an antioxidant are mixed. The composition was melted and prepared with a twin screw extruder manufactured by Nippon Steel, and impregnated with supercritical carbon dioxide at a temperature of 31 ° C. or higher and a pressure of 7.3 MPa or higher, and then the molten material was extruded to obtain the sheet of Example 1 A foam (hereinafter referred to as “foam sheet”) was produced. The details of polypropylene A, polypropylene B, thermoplastic elastomer C, thermoplastic elastomer D, silica E, titanium oxide F, and phenolic antioxidant H are as follows.

(Polypropylene A)
Polypropylene A is homopolypropylene (H-PP) and has a melt flow rate (MFR) of 0.5 g / 10 min at 230 ° C. and 2.16 kg as defined in JIS-K7210. Differential scanning calorimetry The melting temperature measured by (DSC) is 172 ° C., and the crystallization temperature is 113 ° C.
(Polypropylene B)
Polypropylene B is a high melt tension polypropylene (PP) based on homopolypropylene (H-PP) and has a melt flow rate (MFR) of 2.4 g / min at 230 ° C. and 2.16 kg as defined in JIS-K7210. 10 minutes, the melting temperature measured by differential scanning calorimetry (DSC) is 164 ° C., the crystallization temperature is 131 ° C., and the melt tension is 32 cN.
(Thermoplastic elastomer C)
The thermoplastic elastomer C is an ethylene-propylene-diene terpolymer having no crystal component. This ternary copolymer was measured by a high temperature gel permeation chromatograph (GPC) using orthodichlorobenzene as a carry. The weight average molecular weight using standard polystyrene conversion was 300,000 or more, and the ethylene content was 67 wt. % And the diene content is 5% by weight.
(Thermoplastic elastomer D)
The thermoplastic elastomer D is an olefin block copolymer having a linear polyethylene (LLDPE) as a hard segment and an ethylene-octene copolymer (EOR) as a soft segment. This block copolymer has a melt flow rate (MFR) at 190 ° C. and 2.16 kg of 0.5 g / 10 min as defined in JIS K6922-2, and a melting temperature measured by differential scanning calorimetry (DSC). Is 119 ° C. and the crystallization temperature is 93 ° C.
(Silica E)
Silica E is wet precipitated silica.
(Titanium oxide F)
Titanium oxide F is a master batch for using titanium oxide as a colored powder with good handling.
(Phenolic antioxidant H)
The phenolic antioxidant H is “ADEKA ADK STAB AO-60 (manufactured by ADEKA)” which is a general phenolic antioxidant.

<Example 2>
A foamed sheet was produced in the same manner as in Example 1 except that the amount of the thermoplastic elastomer C was 40 parts by mass and the amount of the thermoplastic elastomer D was 15 parts by mass.

<Example 3>
A foamed sheet was produced in the same manner as in Example 2 except that the amount of the thermoplastic elastomer D was 30 parts by mass.

<Example 4>
A foamed sheet was produced in the same manner as in Example 1 except that the amount of the thermoplastic elastomer C was 50 parts by mass and the amount of the thermoplastic elastomer D was 40 parts by mass.

<Example 5>
A foamed sheet was produced in the same manner as in Example 4 except that the amount of the thermoplastic elastomer D was 60 parts by mass.

<Example 6>
A foamed sheet was produced in the same manner as in Example 1 except that the amount of the thermoplastic elastomer C was 55 parts by mass and the amount of the thermoplastic elastomer D was 80 parts by mass.

<Comparative Example 1>
A foamed sheet was produced in the same manner as in Example 1 except that the thermoplastic elastomer D was not blended.

<Comparative example 2>
A foamed sheet was produced in the same manner as in Example 1 except that the amount of the thermoplastic elastomer C was 55 parts by mass and the thermoplastic elastomer D was not blended.

<Comparative Example 3>
A foamed sheet was produced in the same manner as in Example 1 except that the thermoplastic elastomer C was not blended and the blending amount of the thermoplastic elastomer D was 55 parts by mass.

<Comparative example 4>
A foamed sheet was produced in the same manner as in Example 1 except that the amount of the thermoplastic elastomer C was 70 parts by mass and the amount of the thermoplastic elastomer D was 110 parts by mass.

<Comparative Example 5>
A foamed sheet was produced in the same manner as in Example 1 except that the amount of the thermoplastic elastomer C was 135 parts by mass and the thermoplastic elastomer D was not blended.

≪Sample evaluation method≫
Next, a method for evaluating the samples of Examples 1 to 6 and Comparative Examples 1 to 5 created as described above will be described. The evaluation results evaluated by the following method are shown in Table 1 below.

<Number of bubbles>
The number of bubbles was measured as follows. First, the surface layer of the obtained foamed sheet was cut and peeled using a slicer. Next, a photograph of the foam sheet surface was taken at an observation magnification of 200 times using an electron microscope (Microscope VHX-D510, manufactured by Keyence Corporation). Further, as shown in FIG. 7, the contrast of the image obtained in the measuring machine is adjusted, and a straight line of 1 mm (a broken line in FIG. 7) is horizontal to the flow direction of the foam with respect to the clearest image. And the number of bubbles in contact with the straight line was counted (8/1 mm in the case of the example in FIG. 7). FIG. 7 is an explanatory diagram showing an example of a method for counting the number of bubbles in Examples and Comparative Examples.

<Compression hardness>
The compression hardness was evaluated as follows. JIS-K6767 is used as a reference, and a static testing machine (trade name: Autograph AG-X, Inc.) is used in a measurement room controlled at an environmental temperature of 23 ± 5 ° C. and an environmental humidity of 50 (+20, −10)%. Shimadzu Corporation) was used to evaluate the compression strength of the foam sheet. The test piece is 50 mm x 50 mm, the foam sheet is continuously compressed at a compression rate of 1 mm / min, and the test force (load) when 10% compression is read with the load cell, and the compression strength (compression stress) is determined from the test force. Was calculated. The n number is 3, and Table 1 shows the average value of three measurements.

<Foam density>
The density of the foam was determined as follows. Based on JIS-K7112, the density of the foam was calculated | required with the underwater substitution method using Mirage Trading Co., Ltd. electronic hydrometer MD-200S.

<Foaming ratio>
The expansion ratio was determined as follows. The density of the unfoamed material (olefin-based resin composition) was set to 900 kg / m ^3, and the expansion ratio was calculated from the density of the foam obtained by the above method. Specifically, the expansion ratio for obtaining the density of the unfoamed material / the density of each foamed sheet was used.

<MFR of olefin resin composition>
The MFR of the olefin resin composition was measured as follows. The olefin-based resin composition 110 before foaming was kneaded for 8 minutes at 180 ° C. and 100 rpm, using a mixer type of Labo Plast Mill 10C100 manufactured by Toyo Seiki Seisakusho Co., Ltd. with a filling rate of about 80% with respect to the jacket capacity. The sample was measured for melt flow rate (MFR) at 230 ° C. and 2.16 kg as defined in JIS-K7210.

<Dynamic friction coefficient>
The dynamic friction coefficient of the foam sheet was measured as follows. As shown in FIG. 8 (a), a test piece having a size of 100 mm × 200 mm was prepared such that the thickness was 1 mm and the flow direction of the foam 100 was orthogonal to the longitudinal direction of the test piece. Next, using a friction coefficient measuring instrument as shown in FIG. 8 (b), a test piece for measuring the dynamic friction coefficient is attached to the sliding piece and the sample table with an adhesive tape, and the test environment is set with reference to JIS-K7312. The average value obtained by measuring the same part three times at a test speed of 150 mm / min at 23 ° C. and 50% RH was defined as the dynamic friction coefficient of the foamed sheet. In addition, FIG. 8 is explanatory drawing which shows an example of the measuring method of the dynamic friction coefficient in an Example and a comparative example.

≪Sample evaluation results≫
As shown in Table 1, each of the foam sheets of Examples 1 to 6 has a large number of bubbles (appropriate number), a low compression hardness (soft), a large dynamic friction coefficient (good touch), and a density. Was in an appropriate range, and the expansion ratio was high. In particular, in Examples 3 to 6 in which the blending amount of the crystalline elastomer is in the range of 10% by mass or more and 32% by mass or less, the evaluation of the compression hardness, the dynamic friction coefficient, the density, and the expansion ratio was very good.

On the other hand, the foamed sheets of Comparative Examples 1, 2, and 5 that did not contain a crystalline elastomer had high compression hardness and were hard. In particular, the foamed sheets of Comparative Examples 2 and 5 having a large amount of the amorphous elastomer had a high density and a low expansion ratio. Furthermore, the foamed sheet of Comparative Example 5 having a very large amount of the elastomer component is fine with as many as 31 bubbles, but the fact that the cells (bubbles) are too fine is evidence that foaming is insufficient, and as a result, The density was as extremely large and heavy as 90 kg / m ³ . From such a result, by increasing the blending amount of the amorphous elastomer, it is possible to simply increase the number of bubbles, but if the crystalline elastomer is not blended, the gas added as a foaming agent will escape, It was suggested that the expansion ratio was low and the density was high.

  Further, in Comparative Example 3 in which the amorphous elastomer was not blended and in Comparative Example 4 in which the blend amount of the crystalline elastomer was too large, foaming could not be performed and a foamed sheet could not be produced.

<Verification of the effect of supercritical foaming>
The olefin resin foam in the present invention is foamed using supercritical foaming. In order to verify the effect of this supercritical foaming, the foamed sheet of Example 3 and a general-purpose foaming method were used. The foaming states of the foamed sheets using the foaming method with the foaming agent were compared. PE Light A-8 manufactured by Inoac Corporation was used as the foam sheet foamed with the chemical foaming agent.

  Next, the surface of the foamed sheet of Example 3 and the foamed sheet foamed with the chemical foaming agent was cut using a slicer and peeled off. Next, a photograph of the foam sheet surface was taken at an observation magnification of 200 times using an electron microscope (Microscope VHX-D510, manufactured by Keyence Corporation). A photograph at this time is shown in FIG. FIG. 9 is an electron micrograph of a cross section obtained by cutting the surface layer, that is, the skin layer, of the foamed sheet of Example 3 and the foamed sheet foamed with the chemical foaming agent using a slicer or the like.

  As shown in FIG. 9, in the foam sheet of Example 3, moderately fine cells (bubbles) are formed, whereas in the foam sheet foamed using a chemical foaming agent, very coarse cells (virtual cells). The number of bubbles on a straight line of 1 mm was 6).

  The preferred embodiment of the present invention has been described above with reference to the drawings, but the present invention is not limited to the above-described embodiment. That is, it is understood that other forms or various modifications that can be conceived by those skilled in the art within the scope of the invention described in the claims belong to the technical scope of the present invention.

100 Olefin Resin Foam 110 Olefin Resin Composition 111 Cell (Bubble)
120 cell cross section 121 (cell-derived) recess

Claims (18)

An olefinic resin composition in which a crystalline olefinic thermoplastic elastomer and an amorphous olefinic thermoplastic elastomer are mixed in a polyolefin matrix is impregnated with an inert gas in a supercritical state as a foaming agent and then extruded while reducing pressure. A sheet-like olefin resin foam having a plurality of cells, obtained by
The amount of the crystalline olefin-based thermoplastic elastomer is 3% by mass or more and 32% by mass or less based on the whole of the olefin-based resin composition,
An olefin-based resin foam having a cell cross section exposed to the outside on at least one surface.   The olefin resin foam according to claim 1, wherein the 10% compression hardness is 0.008 MPa or less.   The olefin resin foam of Claim 1 or 2 whose dynamic friction coefficient is 2.4 or more. The olefin resin foam according to any one of claims 1 to ³ , wherein the density is 20 kg / m ³ or more and 70 kg / m ³ or less.   The olefin resin foam according to any one of claims 1 to 4, wherein the polyolefin is a polypropylene resin.   The olefin resin foam according to claim 5, wherein the polypropylene resin is homopolypropylene.   The olefin resin foam according to any one of claims 1 to 6, further comprising a foam nucleating agent in the olefin resin composition.   The olefin resin foam according to any one of claims 1 to 7, wherein the inert gas is carbon dioxide.   The total blending amount of the crystalline olefin-based thermoplastic elastomer and the non-crystalline olefin-based thermoplastic elastomer is 23% by mass or more based on the whole of the olefin-based resin composition. The olefin resin foam according to claim 1.   The crystalline olefin-based thermoplastic elastomer is a block copolymer having linear polyethylene as a hard segment and having an ethylene-octene copolymer as a soft segment. The olefin resin foam according to the description. A sheet-like olefin resin foam having a plurality of cells in which a olefin resin composition containing a crystalline olefin thermoplastic elastomer and an amorphous olefin thermoplastic elastomer is foamed in a polyolefin matrix,
The amount of the crystalline olefin-based thermoplastic elastomer is 3% by mass or more and 32% by mass or less based on the whole of the olefin-based resin composition,
In the cross section of the foam, the number of cells in contact with a virtual straight line having a length of 1 mm drawn in the flow direction of the foam is 10 or more,
An olefin-based resin foam having a cell cross section exposed to the outside on at least one surface. Mixing a crystalline olefinic thermoplastic elastomer and an amorphous olefinic thermoplastic elastomer in a polyolefin matrix to obtain an olefinic resin composition;
After impregnating the molten olefin resin composition with a supercritical inert gas as a foaming agent, the olefin resin composition impregnated with the inert gas is extruded while reducing pressure. Obtaining a sheet-like foam having a plurality of cells;
Exposing the cell cross section on the surface side of at least one of the sheet-like foam to the outside;
Including
The manufacturing method of the olefin resin foam which makes the compounding quantity of the said crystalline olefin type thermoplastic elastomer 3 mass% or more and 32 mass% or less with respect to the whole said olefin resin composition.   The method for producing an olefin resin foam according to claim 12, wherein a polypropylene resin is used as the polyolefin.   The method for producing an olefin resin foam according to claim 13, wherein homopolypropylene is used as the polypropylene resin.   The method for producing an olefin resin foam according to any one of claims 12 to 14, wherein a foam nucleating agent is further added to the olefin resin composition.   The method for producing an olefin resin foam according to any one of claims 12 to 15, wherein carbon dioxide is used as the inert gas.   The total amount of the crystalline olefin-based thermoplastic elastomer and the non-crystalline olefin-based thermoplastic elastomer is 23% by mass or more based on the total amount of the olefin-based resin composition. A method for producing an olefin resin foam according to claim 1. The block copolymer having linear polyethylene as a hard segment and having an ethylene-octene copolymer as a soft segment is used as the crystalline olefin-based thermoplastic elastomer according to any one of claims 12 to 17. The manufacturing method of the olefin resin foam of description.