JP5705605B2 - Polypropylene resin porous sheet and method for producing polypropylene resin porous sheet - Google Patents

Description

  The present invention relates to a porous polypropylene-based resin sheet and a polypropylene-based resin excellent in air permeability that can be suitably used as a packaging product, sanitary product, livestock product, building product, medical product, separation membrane, light diffusion membrane, reflection sheet, or battery separator. The present invention relates to a method for producing a porous sheet.

  A porous polymer body having a large number of fine communication holes of this type is a separation membrane used for production of ultrapure water, production of chemicals, water treatment, etc., a waterproof and moisture permeable film and sheet used for medical and sanitary materials, It is used in various fields such as waterproof and moisture permeable sheets used for building applications such as house wraps and roof base materials, and battery separators used for batteries.

  Various techniques as described below have been proposed as a technique for forming a large number of such fine communication holes.

  For example, in Patent Document 1, a porous film is obtained by kneading and sheeting ultrahigh molecular weight polyethylene and a solvent, drawing the solvent, and then extracting the solvent.

  Further, Patent Document 2 discloses a porous film or sheet having communication properties by inflation-molding a resin composition containing a polyolefin resin and a filler, and uniaxially stretching the obtained film or sheet in the take-off direction. Proposed.

  Patent Document 3 discloses a method for obtaining a porous film in which a crystalline polypropylene sheet formed at a high draft ratio is heat-treated as necessary and stretched in at least one direction to fibrillate between crystal lamellae. Has been.

  In Patent Document 4, ethylene propylene block polymer having an ethylene content of about 10 to about 50% by mass as component (A), and ethylene or an α-olefin comonomer having 4 to 8 carbon atoms as component (B) is 10. Selected from propylene homopolymers or random propylene copolymers having up to% by weight and low molecular weight propylene as component (C), calcium carbonate as component (D), and beta-spherulite nucleating agent and calcium carbonate as component (E) A polyolefin resin composition consisting of a general classification and an oriented microporous film prepared therefrom are disclosed. Specifically, in these microporous films having microporous cells and continuous pores between the cells, the polymer composition has a weight ratio of (A) / (B) of about 5-30 / 95-70. And (E) when the beta spherulite-forming nucleating agent is present at about 0.1 to 10 ppm, it is formed by a process including a step of removing beta spherulites before orientation. In addition, when substantially free of calcium carbonate as component (D) and beta spherulite nucleating agent as component (E), the weight ratio of (A) / (B) is about 30 to 95/70 to 5. And about 100 parts by weight of the component (A) and the component (B), the low molecular weight polypropylene as the component (C) is present in an amount of about 5 to 20 parts by weight, and the polymer composition is the component (E). When the beta spherulite nucleating agent is 0.1 to 10 ppm and the calcium carbonate which is the component (D) has about 5 to 30 parts by weight, the low molecular weight polypropylene which is the component (C) is the component (A) and (B) Present at about 1 to 10 parts by weight per 100 parts by weight of the ingredients.

JP-A-5-25305 Japanese Patent No. 3166279 Japanese Patent Publication No. 6-79659 Japanese Patent No. 3291307

  However, in the method disclosed in Patent Document 1, solvent extraction is performed by washing with an organic solvent for washing. However, in this case, a large amount of organic solvent is required, which is not preferable from an environmental aspect.

  In the method disclosed in Patent Document 2, the porous film or sheet obtained by these methods has a large mass (basis weight) per unit area due to the presence of the filler in the sheet, so that the weight can be reduced. There is room for improvement.

  Further, in the method disclosed in Patent Document 3, it is very difficult to control crystallization, and since pores are formed by fibrillating between crystal lamellae by stretching, it is difficult to obtain a porous film having a high porosity. Had.

  In addition, in the method disclosed in Patent Document 4, in the case of having a beta spherulite nucleating agent, a beta spherulite formation process is required, and the cooling rate of the film is limited. It needs to be cooled. In addition, when it contains substantially no beta spherulite nucleating agent, the low molecular weight polypropylene is present, so the heat resistance and durability of the resin composition will be poor, and the thermal stability during film formation will be low, leading to industrial productivity. Often inferior.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a polypropylene resin porous sheet having good workability and pore formation at the time of stretching and excellent air permeability. It is to provide.

As a result of intensive studies, the present inventors have found that the above-described problems can be solved by using a specific polypropylene resin as a main component, and have completed the present invention.
That is, the present invention is as follows.
(1) The main component is a polypropylene resin composition in which at least two peak tangent temperatures of loss tangent measured at a frequency of 10 Hz by dynamic viscoelasticity measurement are between −60 and 20 ° C., and the pore magnification is A polypropylene resin porous sheet characterized by being 1.1 to 5 times.

(2) Preferably, the said polypropylene resin composition is a mixed resin composition of the following (A) component and (B) component, and (A) component in this composition is 70-40 mass%, ( B) A polypropylene resin porous sheet, wherein the component is 30 to 60% by mass.
(A) Component: Polypropylene (B) Component: Ethylene-propylene copolymer having a propylene ratio of 40 to 60 mol%

(3) A molded body mainly composed of a polypropylene resin composition having at least two peak tangent temperatures of loss tangent measured at a frequency of 10 Hz by dynamic viscoelasticity measurement at −60 to 20 ° C. A method for producing a porous polypropylene-based resin sheet, wherein the porous resin sheet is made porous by passing at least one step of stretching in at least one direction at a stretching temperature of 35 ° C.

(4) The aspect ratio of the domain in the polypropylene resin composition in which at least two peak tangent temperatures of loss tangent measured at a frequency of 10 Hz by dynamic viscoelasticity measurement are between −60 to 20 ° C. was controlled to 30 or less. A method for producing a polypropylene resin porous sheet, wherein the molded body is made porous by at least one or more passes through a step of stretching in at least one direction at a stretching temperature of 0 ° C to 35 ° C.

  According to the present invention, it is possible to provide a polypropylene resin porous sheet having good air permeability.

It is a dynamic viscoelasticity measurement result of the molded object which consists of a polypropylene resin composition of Example 1. FIG. 4 is a result of dynamic viscoelasticity measurement of a molded body made of the polypropylene resin composition of Comparative Example 1.

The present invention will be described in detail below.
It should be noted that the upper limit and lower limit of the numerical range in the present invention are the same as those in the present invention as long as they have the same effects as those in the numerical range, even if they are slightly outside the numerical range characterized by the present invention. It is included in the equivalent range.

  First, the polypropylene resin porous sheet of the present invention is composed mainly of a propylene resin composition having at least two peak tangent loss tangents measured at a frequency of 10 Hz by dynamic viscoelasticity measurement between −60 and 20 ° C. It is characterized by.

  In the polypropylene resin composition of the present invention, it is important that at least two peak tangent temperatures of loss tangent measured at a frequency of 10 Hz by dynamic viscoelasticity measurement are between −60 and 20 ° C. The peak temperature of the loss tangent referred to in the present invention is a temperature at which the loss tangent (tan δ) exhibits a peak value (maximum value). Here, it is preferable that at least two peak tangent temperatures of loss tangent exist between −60 and 20 ° C., since it can be made porous without breaking when stretched in at least one direction. In terms of stretch workability, the lower limit of the peak temperature of loss tangent is −60 ° C. or higher, and the upper limit of the peak temperature on the high temperature side is 20 ° C. or lower in terms of ease of porosity when stretched. Further, since at least two peak tangent temperatures of loss tangent exist in the temperature range, both stretchability and easiness of pore formation by stretching can be achieved. That is, when stretched in at least one direction, having a peak temperature on the low temperature side (−60 to 0 ° C.) makes the stretchability good, making it difficult for the film to break during stretching, and at the same time the high temperature side (− It is considered that the easiness of porosity by stretching is improved by having a peak temperature at 20 to 20 ° C. Thus, the presence of at least two peak temperatures of loss tangent between −60 to 20 ° C. makes it possible to achieve a balance between stretchability when stretched in at least one direction and ease of porosity by stretching. It is. Moreover, if it is a range which does not exceed the main point of this invention, three or more peaks of the loss tangent measured by dynamic viscoelasticity may exist between -60-20 degreeC. The upper limit of the number of realistic loss tangent peaks is five.

  A polypropylene resin composition will not be specifically limited if the above-mentioned characteristic is satisfied. For example, in order for at least two peak tangent temperatures measured at a frequency of 10 Hz by dynamic viscoelasticity measurement to exist between −60 and 20 ° C., a propylene-α-olefin copolymer is used as a polypropylene resin composition. Polymers, blends of polypropylene and ethylene-α-olefin copolymers, and the like can also be used. In the present invention, the polypropylene-based resin composition has a function of developing a good porous shape. Therefore, the component (A) 70 to 40% by mass of polypropylene and an ethylene-propylene copolymer having a propylene ratio of 40 to 60 mol% are used. A mixed resin composition with (B) component 30 to 60% by mass, which is a polymer, is preferably used, and more preferably (A) component 60 to 40% by mass and (B) component 40 to 60% by mass. Is a mixed resin composition. If the ethylene ratio of the ethylene-propylene copolymer (B) is 40 to 60 mol%, the ethylene-propylene copolymer is uniformly and finely dispersed in the propylene-based resin composition. This is preferable. In addition, you may have other components other than the said (A) component and (B) component in the range which does not impair this invention in the polypropylene resin composition in this invention. As the other component, a resin having a melting point lower than that of the component (A) which is polypropylene can be cited as a suitable example. More specifically, an ethylene-α olefin copolymer or a styrene elastomer resin can be exemplified. Can do. It is preferable that the compounding quantity of the said other resin component is 1-10 mass% with respect to the whole polypropylene resin composition.

  Examples of the ethylene-propylene copolymer as the component (B) include an alternating interpolymer of ethylene and propylene, a random copolymer, a block copolymer, and a graft copolymer. The copolymer suitable for the present invention is a block copolymer because it has a high phase structure (morphology) composed of a mixed resin composition of the component (A) and the component (B) and a good phase separation structure. , Graft copolymers, and random copolymers with high blocking properties.

  Next, the polypropylene resin composition in the present invention has a crystallization melting peak temperature of 150 ° C. to 170 ° C. and a crystallization melting heat amount of 20 when scanned at a rate of 10 ° C./min by differential scanning calorimetry. It is preferably -50 J / g. By making it within such a range, it is preferable because it becomes porous without breaking when stretched in at least one direction, and the heat of crystallization and melting is preferably lower in terms of ease of stretching, Higher is preferable in terms of easiness of porosity formation. The crystallization melting peak temperature and the crystallization melting heat amount in the present invention can be measured as follows. That is, using a differential thermal scanning calorimeter DSC-7 manufactured by PerkinElmer, approximately 10 mg of a polypropylene resin composition was accurately weighed in an aluminum pan for DSC measurement according to JIS K7121, and from room temperature to 10 ° C./min. The temperature is raised to 200 ° C. at a heating rate of From the thermogram in this heating process, the crystallization melting peak temperature (Tm) and the heat of crystal melting (ΔHm) can be determined.

  The MFR (JIS K7210, 230 ° C., load: 21.18 N) of the polypropylene resin composition is preferably 1 to 10 g / 10 minutes. Within such a range, the back pressure or the like does not increase abruptly during extrusion molding, and preferable moldability can be obtained, which is preferable. Therefore, the MFR is preferably 2 to 10 g / 10 minutes, more preferably 3 to 10 g / 10 minutes.

  The production method of the polypropylene resin composition is not particularly limited, and any production method may be used as long as the above characteristics are satisfied. For example, it can be exemplified that a polypropylene resin composition is produced by continuously polymerizing polypropylene and a copolymer by multistage polymerization. A method of polymerizing a polypropylene resin composition by polymerizing polypropylene in the first stage and then polymerizing a copolymer in the presence of polypropylene in the second stage by using a plurality of polymerization vessels can be exemplified. This continuous polymerization method is preferable because the domains in the polypropylene resin composition are uniformly dispersed. Moreover, you may manufacture a polypropylene-type resin composition by mixing the polypropylene obtained by superposing | polymerizing individually and ethylene-alpha-olefin copolymer by melt kneading | mixing etc. Specifically, for example, a method of melt kneading an ethylene-α-olefin copolymer polymerized using a Ziegler-Natta catalyst such as a titanium-supported catalyst can be exemplified.

  In the present invention, commercially available raw materials can also be used. Specific examples of the polypropylene resin composition that can be used advantageously in the present invention include a trade name “ZELAS” of Mitsubishi Chemical Corporation.

  The polypropylene resin composition used in the present embodiment is necessary for the purpose of further adjusting and improving various physical properties such as antistatic properties, heat resistance, slipperiness, and mechanical properties within a range not exceeding the gist of the present invention. Various additives can be appropriately blended.

  Here, as various additives, for example, antioxidants, neutralizers, ultraviolet absorbers, antifogging agents, antistatic agents and other surfactants used in ordinary polyolefins, lubricants, anti-blocking agents, antibacterial agents, A pigment etc. are mentioned and it will not specifically limit unless the main point of this invention is exceeded.

  In the polypropylene resin composition used in the present embodiment, the residual solvent is preferably 1000 ppm or less, and the upper limit of the inorganic filler is preferably less than 5% by mass.

  The porosity of the polypropylene resin porous sheet of the present invention is preferably in the range of 1.1 to 5 times. The term “vacancy magnification” as used herein is a numerical value indicating the proportion of the space portion in the polypropylene resin porous sheet, and is a ratio between the density of the polypropylene resin composition and the apparent specific gravity of the polypropylene resin porous sheet. It is preferable to set the porosity to be in the above range because it has substantial communication properties and good mechanical strength. The porosity is more preferably 1.3 to 4 times, particularly preferably 1.5 to 3.7 times.

  The air permeability, which is an index of the connectivity of the polypropylene resin porous sheet of the present invention, is preferably in the range of 1 to 9,999 seconds / 100 ml. This means that if the air permeability is larger than 9,999 seconds / 100 ml, the numerical value of the air permeability will be obtained in the measurement, but it means that the structure is very poor in communication, so there is virtually no communication. May be equal to It is preferably 1 to 5,000 seconds / 100 ml, more preferably 10 to 5,000 seconds / 100 ml, and particularly preferably 10 to 2,000 seconds / 100 ml. In addition, the air permeability in this invention is a measured value based on JISP8117.

  The range required for the porosity and air permeability of the polypropylene resin porous sheet differ depending on the application. For example, when used for sanitary goods such as diapers and sanitary products, the air permeability is preferably 1 to 2,000 seconds / 100 ml, and when used as a battery separator, the air permeability is 1 to 500 seconds / 100 ml. Is preferably used

  The porosity and air permeability of the polypropylene resin porous sheet can be adjusted to a predetermined range by adjusting the stretching temperature and the stretching ratio. For example, when the porosity is larger than a desired value or when the air permeability is smaller than a desired value, the stretching ratio may be appropriately adjusted by decreasing the stretching ratio or increasing the stretching temperature. On the contrary, when the pore ratio is smaller than a desired value or when the air permeability is larger than a desired value, the stretching ratio may be increased or the stretching temperature may be adjusted as appropriate.

  Next, the manufacturing method of the molded object of this invention is demonstrated. In addition, the molded object in this invention is a sheet-like molded object before making porous. Various known production methods can be applied to the method for producing a molded body in the present invention, and the method is not particularly limited as long as the gist of the present invention is not exceeded. Examples of the method for producing the molded body include an inflation film molding method, a T-die film molding method, and a calendar molding method. Among these, in the present invention, the T-die film forming method is preferably used because of high accuracy of film thickness.

  In the present invention, it is preferable to control the aspect ratio of the domains in the obtained molded article to 30 or less. The aspect ratio of the domain in the present invention refers to the ratio of the average particle diameter in the minor axis direction and the major axis direction. By controlling the aspect ratio of the domain to 30 or less, it becomes easy to become porous by stretching, and even when stretched at a low magnification, a favorable porous structure is obtained and air permeability is improved, which is preferable. The size of the domain can be variously changed as necessary, but it is substantially 0.5 to 3 μm, preferably 0.5 to 2 μm. Here, the domain size refers to the average diameter of domain components. That is, the average value in the minor axis direction and the major axis direction. The shape of the domain is not particularly limited as long as the aspect ratio is 30 or less, and examples thereof include a spherical structure and a cylinder structure. The domain size (average particle size) in the present invention was obtained by performing pre-dyeing treatment (RuO4 gas phase dyeing) on the sheet before stretching and using a transmission electron microscope (JEM-1200EX). Observe near the center of the cross section of the molded body, select 100 randomly and observe and average.

  Next, the method for making a porous porous sheet of the present invention will be described. The polypropylene-based porous sheet in the present invention is made porous by stretching in at least one direction at a stretching temperature of 0 ° C to 35 ° C. In general stretching, a uniaxial stretching method in which stretching is performed in the machine direction (MD), a uniaxial stretching method in the longitudinal direction, and then a sequential biaxial stretching method in which stretching is performed in the transverse direction (TD) by a tenter stretching machine or the like It is obtained by a simultaneous biaxial stretching method in which stretching is performed simultaneously. These stretching temperatures are 0 ° C. to 35 ° C. in the case of the uniaxial stretching method and simultaneously the axial stretching method, and in the case of the sequential biaxial stretching method, the stretching temperature at the time of uniaxial stretching is 0 to 35 ° C. is important. If the stretching temperature is within such a range, a good pore structure can be formed by stretching in at least one direction. The above temperature range is preferably 15 ° C to 35 ° C, particularly preferably 15 ° C to 30 ° C.

  The stretching ratio is at least 1.1 times or more in the uniaxial direction, preferably 1.2 times to 4 times, more preferably 1.3 times to 4 times. Here, the draw ratio refers to the ratio of the length after drawing to the original length. In the case of sequential biaxial stretching, the stretching ratio is preferably 1.7 times to 20 times, more preferably 2 times to 15 times, and particularly preferably 2 times to 13 times in terms of deformation ratio. Here, the deformation ratio is a value obtained by dividing the thickness of the molded body by the thickness of the porous sheet that can be obtained. For example, when the thickness of the molded body is 500 μm and the thickness of the obtained porous sheet is 100 μm, the deformation ratio is 5 times. If it is in such a range, it is preferable because excellent air permeation performance is exhibited.

  The thickness of the polypropylene resin porous sheet is not particularly limited, but is generally in the range of about 10 μm to 2 mm, typically about 50 μm to 1 mm.

  When the polypropylene resin composition according to the present invention is the resin composition A, the polypropylene resin porous sheet of the present invention is composed mainly of the resin composition B in addition to the A layer mainly composed of the resin composition A. B layer may be included. The laminated structure of the polypropylene resin sheet according to the present embodiment is not particularly limited, but examples of the laminated structure include a two-layer structure of A layer / B layer, A layer / B layer / A layer, or B layer / A layer / B. A three-layer structure of layers can be given, and a multilayer structure can also be formed. In the present invention, as a method of forming a laminated structure, for example, there are methods such as extrusion lamination, sand lamination, and coextrusion, and further an adhesive (including an adhesive sheet) is interposed between the A layer and the B layer. There is a lamination method such as a method of heat-sealing the layer A and the layer B without using an adhesive, but it is not particularly limited.

  The resin constituting the resin composition B is not particularly limited as long as it does not impair the effects of the present invention with a thermoplastic resin that can be formed into a film, and a polyolefin-based resin because it can impart good planarity, Polyester resins, polycarbonate resins, acrylic resins, polystyrene resins, fluorine resins and the like are preferable. The same resin as that constituting the resin composition A may be selected.

  The polypropylene resin porous sheet of the present invention can be subjected to hydrophilic treatment such as surfactant treatment, corona discharge treatment, low temperature plasma treatment, sulfonation treatment, ultraviolet treatment, radiation graft treatment, etc., if necessary. Various coating films can be formed.

  The polypropylene resin porous sheet of the present invention having the above characteristics can be applied to various uses that require air permeability. For example, disposable paper diapers, sanitary materials such as pads or bed sheets for absorbing bodily fluids such as sanitary items, medical materials such as surgical clothing or base materials for hot compresses, medical materials such as jumpers, sportswear or rainwear, wallpaper, and roofs It can be suitably used as a material for building materials such as a base material, a heat insulating material, and a sound absorbing material, a moistureproof material, an oxygen scavenger, a disposable body warmer, a freshness-keeping packaging, or a packaging material.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, the various measured value and evaluation about the film displayed in this specification were performed as follows. Here, the flow direction from the extruder of the film is called the vertical direction, and the orthogonal direction is called the horizontal direction.

(1) Thickness The obtained polypropylene-based resin porous sheet was measured unspecified in five locations with a 1/1000 mm dial gauge, and the average was taken as the thickness.

(2) Measurement of dynamic viscoelasticity The molded body before being made porous is subjected to a dynamic viscoelasticity measurement method described in JIS K-7198 A method, using a viscoelasticity spectrometer “VES-F3” manufactured by Iwamoto Seisakusho Co., Ltd. At a vibration frequency of 10 Hz and a strain of 0.1%, the temperature was increased from −100 ° C. to 170 ° C. at a rate of temperature increase of 3 ° C./min, and the peak temperature of the obtained loss tangent (tan δ) was measured.

(3) Air permeability (Gurley value)
A sample was cut out from the obtained polypropylene resin porous sheet with a diameter of φ40, and the air permeability (second / 100 ml) was measured according to JIS P 8117.

(4) Porosity magnification The obtained polypropylene resin porous sheet was cut into 10 cm square, the mass and thickness of the sample were measured, and the apparent specific gravity (ρ) was calculated from the ratio of the mass and thickness, and the polypropylene resin composition The ratio ρ0 / ρ with respect to the density (ρ0) of the object was determined as the hole magnification. In addition, since the hole magnification greatly depends on the thickness, the average value of 5 times was used.

(Example 1)
As a polypropylene resin composition, a mixed resin composition (MFR = 7.0 g / 10) of polypropylene: 48 mass% and ethylene-propylene copolymer: 52 mass% (propylene component in the copolymer: 48 mol%). Extruding at a setting temperature of 180 to 200 ° C. with a φ40 mm single screw extruder equipped with a T die die having a width of 300 mm and a lip gap of 1 mm. It was taken up with a cast roll at 0 ° C. and cooled and solidified to obtain a molded body having a width of 210 mm and a thickness of 330 μm. The dynamic viscoelasticity measurement result of the molded body is shown in FIG. Then, using a film roll longitudinal stretching machine, stretching was performed at a stretching temperature and a stretching ratio of Condition 1 listed in Table 1. The results of evaluating the obtained sheet are shown in Table 2.

(Comparative Example 1)
As a polypropylene resin composition, a mixed resin composition (MFR = 7.0 g / 10) of polypropylene: 60% by mass and ethylene-propylene copolymer: 40% by mass (propylene component in the copolymer: 33 mol%). A molded body having a width of 200 mm and a thickness of 330 μm was obtained in the same manner as in Example 1 using a minute: 230 ° C. and a load: 21.18 N). The dynamic viscoelasticity measurement result of the molded body is shown in FIG. Then, using a film roll longitudinal stretching machine, stretching was performed at a stretching temperature and a stretching ratio of Condition 1 listed in Table 1. However, the obtained sheet was hardly whitened and air permeability was not exhibited.

(Example 2)
In Example 1, longitudinal stretching was performed using a film roll longitudinal stretching machine under the condition 2 described in Table 1, and then stretching was performed in the transverse direction using a film tenter facility manufactured by Kyoto Machine. The results of evaluating the obtained sheet are shown in Table 2.

(Example 3)
In Example 1, longitudinal stretching was performed using a film roll longitudinal stretching machine under the condition 3 described in Table 1, and then stretched in the transverse direction using a film tenter facility manufactured by Kyoto Machine. The results of evaluating the obtained sheet are shown in Table 2.

Example 4
In Example 1, longitudinal stretching was performed using a film roll longitudinal stretching machine under the condition 4 described in Table 1. The results of evaluating the obtained sheet are shown in Table 2.

(Example 5)
In Example 1, longitudinal stretching was performed using a film roll longitudinal stretching machine under the condition 5 shown in Table 1, and then stretching was performed in the transverse direction using a film tenter facility manufactured by Kyoto Machine. The results of evaluating the obtained sheet are shown in Table 2.

(Example 6)
In Example 1, the film was longitudinally stretched using a film roll longitudinal stretching machine under the condition 6 shown in Table 1, and then stretched in the transverse direction using a film tenter facility manufactured by Kyoto Machine. The results of evaluating the obtained sheet are shown in Table 2.

(Comparative Example 2)
In Example 1, longitudinal stretching was performed using a film roll longitudinal stretching machine under the condition 7 described in Table 1. When the longitudinal stretching temperature was 50 ° C., breakage was observed during stretching, and a porous sheet could not be obtained.

  From Table 2, it can be seen that the polypropylene resin porous sheet defined in the present invention is a porous sheet having good air permeability. Moreover, it can confirm that it can be made porous without a fracture | rupture trouble at the time of an extending | stretching process (Examples 1-6). On the other hand, when the peak temperature of the loss tangent measured at a frequency of 10 Hz by the dynamic viscoelasticity measurement of the polypropylene resin composition is single (Comparative Example 1), the formation of pores at the time of stretching is poor and ventilation is performed. When the stretching property does not appear and the stretching temperature during stretching is higher than 35 ° C. (Comparative Example 2), it can be confirmed that there is a problem that breakage occurs during stretching.

  It is a polypropylene resin porous sheet and a polypropylene resin porous sheet of the present invention, and has excellent breathability, as a packaging product, sanitary product, livestock product, building product, medical product, separation membrane, light diffusion film, reflection sheet or battery separator. It can be suitably used.

Claims (3)

There are at least two peak temperatures of loss tangent measured at a frequency of 10 Hz by dynamic viscoelasticity measurement between −60 and 20 ° C., at least one peak between −60 and 0 ° C., and −20 to 20 ° C. is a main component of polypropylene resin composition that having a least one other peak between, and holes magnification a 1.1 to 5 Baidea Lupo polypropylene-based resin porous sheet, The polypropylene resin composition is a mixed resin composition of the following component (A) and component (B), the component (A) in the composition is 60 to 40% by mass, and the component (B) is 40 to 40%. A polypropylene resin porous sheet, which is 60% by mass, has an MFR measured under the following conditions of the polypropylene resin composition of 3 to 10 g / 10 min, and a thickness of 50 μm to 1 mm .
(A) component: polypropylene
Component (B): an ethylene-propylene copolymer having a propylene ratio of 40 to 60 mol%
(Measurement conditions of MFR) Measured at 230 ° C. and a load of 21.18 N according to JIS K7210. There are at least two peak temperatures of loss tangent measured at a frequency of 10 Hz by dynamic viscoelasticity measurement between −60 and 20 ° C., at least one peak between −60 and 0 ° C., and −20 to 20 ° C. porous by at least a molded body consisting mainly of polypropylene resin composition which have a another one peak, go through 0 ° C. to 35 ° C. stretching temperature in at least one direction in the stretching to step more than once during the a Lupo polypropylene-based resin porous sheet manufacturing method of turn into, the polypropylene-based resin composition is a mixed resin composition of the following components (a) and component (B) in the composition (a The component is 60 to 40% by mass, the component (B) is 40 to 60% by mass, the MFR measured under the following conditions of the polypropylene resin composition is 3 to 10 g / 10 min, and the thickness is 50 μm to 1 mm. To Polypropylene resin porous sheet manufacturing method characterized by and.
(A) component: polypropylene
Component (B): an ethylene-propylene copolymer having a propylene ratio of 40 to 60 mol%
(Measurement conditions of MFR) Measured at 230 ° C. and a load of 21.18 N according to JIS K7210. The manufacturing method of the polypropylene resin porous sheet of Claim 2 which controlled the aspect ratio of the domain in the said polypropylene resin composition to 30 or less.

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