JP2012140630A - Method for manufacturing foam, and foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new foam in which a high-order structure (morphology) of a molded body before foaming and a foaming structure are easily controlled.SOLUTION: The molded body is obtained which contains an (a) component, and a (b) component as main components wherein the average size of the (b) component is controlled at 5 μm; a pressurized gas is impregnated in the molded body; and thereafter, the resultant molded body is foamed mainly in the region of the (b) component within such a temperature range that the elastic modulus of the molded body becomes ≤5.0×10Pa to obtain a sheet-shape molded body having a thickness of ≥50 μm and ≤500 μm.

Description

  The present invention relates to a method for producing a foam, and more particularly to a method for producing a foam in which the foam structure can be easily controlled, and a foam obtained by the production method.

Conventionally, foams made of thermoplastic resins typified by polyolefin resins, polystyrene resins and the like have been widely used in the fields of food containers, building materials, etc. due to their excellent heat insulation and buffering properties.
As a typical method for producing a thermoplastic resin foam, there are a chemical foaming method and a physical foaming method. The chemical foaming method is a method in which a low molecular weight chemical foaming agent is mixed and foamed by heating to a temperature higher than the decomposition temperature of the foaming agent. The physical foaming method is a method of foam molding by supplying a low boiling point organic compound such as butane and kneading and then extruding it into a low pressure region. This method is characterized in that various foams from low magnification to high magnification can be easily produced by adjusting the amount of foaming agent added to the resin, but when the resin is melted and extruded, However, there is a problem that it is difficult to control the porous structure, for example, the thickness and density of the obtained resin molding are not uniform.

  On the other hand, in order to expand the performance range of the foam material by refining the bubbles of the foam (for example, the average cell diameter is 10 μm or less) compared to the conventional foaming method, specifically, for example, foaming There is a technique called microcellular plastic as a technique for suppressing a reduction in strength accompanying an increase in magnification or improving a strength. Specifically, this method includes (1) impregnating a thermoplastic resin in a high-pressure vessel with a gas such as nitrogen or carbon dioxide under high pressure or in a supercritical state, and then (2) a thermoplastic impregnated with the gas. The resin is taken out from the high-pressure vessel, heated to a temperature higher than the glass transition temperature of the thermoplastic resin with an oil bath or the like, and (3) a fine bubble foam is obtained by inducing nucleation and growing bubbles. is there.

  As such a production method, Patent Document 1 discloses that in a polymer alloy obtained by mixing and dispersing at least one crystalline thermoplastic resin and at least one amorphous thermoplastic resin under pressure. Disclosed is a method for producing a thermoplastic resin foam, comprising: a step of containing a non-reactive gas; and a step of foaming a polymer alloy containing the non-reactive gas by heating under no pressure. ing. Patent Document 2 discloses the production of a copolymer resin foam characterized in that a high pressure gas is brought into contact with a resin material having a microphase separation structure made of a copolymer of two or more types of monomers and then foamed. A method is disclosed. Patent Document 3 includes a resin (A) and a resin (B) that are different in solubility and diffusion coefficient of carbon dioxide and incompatible with each other, and the mass ratio of (A) / (B) is 1 to 99 /. A method for producing a resin foam molded article, wherein the resin molded article 99-1 is impregnated with carbon dioxide at a temperature not higher than the melting points of the resin (A) and the resin (B), and then foamed. A resin molded body obtained by the manufacturing method is disclosed.

JP-A-6-55651 JP 2001-151924 A JP 2005-271504 A

  However, in any of the manufacturing methods described above, a manufacturing method that actively controls the higher-order structure (morphology) of the molded body before foaming and reflects the higher-order structure (morphology) of the molded body before foaming is disclosed. Not.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for producing a foam and a foam in which the foam structure can be easily controlled.

  As a result of intensive studies, the inventors have found that the above problem can be solved by impregnating a pressurized gas after controlling the structure of the molded body before foaming and foaming in a specific temperature range, The present invention has been completed.

That is, the present invention is as follows.
[1] As a main component, the component (a) and the component (b) are contained in a mass ratio (a) / (b) = 97/3 to 60/40, and the average size of the component (b) After obtaining a molded product controlled to 5 μm or less and impregnating the molded product with a pressurized gas, mainly in the temperature range where the elastic modulus of the molded product is 5.0 × 10 ⁸ Pa or less ( b) A method for producing a foam, characterized by foaming in the component region.

[2] The component (a) is a crystalline resin, the component (b) is an amorphous resin, the melting point Tma of the component (a), and the glass transition temperature Tgb of the component (b) Satisfies the following formula (1): The method for producing a foam according to [1].
Tma> Tgb (1)

  [3] A foam obtained by the production method according to [1] or [2].

  In the method for producing a foam of the present invention, foaming is performed using a pressurized gas after controlling the higher order structure (morphology) of the molded body. For this reason, the porous structure of the foam, the expansion ratio, and the like can be easily controlled. Further, the obtained foam can be effectively used in fields that require light weight and high strength, optical properties, heat insulation, low dielectric properties, gas permeability, and ion permeability.

2 is a morphological observation image (magnification 5000 times) of the molded body 1 obtained in Example 1. It is the temperature dependence of the elasticity modulus of the molded object 1 obtained in Example 1. FIG. It is an observation image (magnification 3000 times) of the foam 1 obtained in Example 1. It is an observation image (magnification 3000 times) of the foam 2 obtained in Example 1. It is an observation image (magnification 6000 times) of the foam which performed the etching process to the foam 2 obtained in Example 1. FIG. 3 is a morphological observation image (magnification 10,000 times) of the molded body 2 obtained in Example 2. It is the temperature dependence of the elasticity modulus of the molded object 2, the (a) component obtained in Example 2, and the (b) component. It is an observation image (magnification 3000 times) of the foam 3 obtained in Example 2. 4 is a morphology observation image (magnification 2500 times) of the molded body 3 obtained in Example 3. FIG. It is the temperature dependence of the elasticity modulus of the molded object 3, the (a) component obtained in Example 3, and the (b) component. It is an observation image (magnification 3000 times) of the foam 4 obtained in Example 3. It is the temperature dependence of the elastic modulus of the molded body obtained in Comparative Example 2. It is the temperature dependence of the elasticity modulus of the molded object 4 obtained in Example 4. FIG. It is an observation image (magnification 3000 times) of the foam 5 obtained in Example 4. 6 is a morphological observation image (magnification 2500 times) of the molded body 5 obtained in Example 5. It is temperature dependence of the elasticity modulus of the molded object 5 obtained in Example 5. FIG. 6 is a morphology observation image (magnification 2500 times) of the molded body 6 obtained in Example 5. It is an observation image (magnification 3000 times) of the foam 6 obtained in Example 5. It is an observation image (magnification 3000 times) of the foam 7 obtained in Example 5. It is a morphology observation image (magnification 5000 times) of the molded body 7 of Comparative Example 3 and Example 6. It is a temperature dependence of the elasticity modulus of the molded object 7 of the comparative example 3 and Example 6. FIG. It is an observation image (magnification 3000 times) of the foam 8 obtained in Example 6. It is an observation image (magnification 3000 times) of the foam 9 obtained in Example 6.

The present invention will be described in detail below.
It should be noted that the upper and lower limits of the numerical range in the present invention are those of the present invention as long as they have the same operational effects as those in the numerical range even if they are slightly outside the numerical range specified by the present invention. It is included in the equivalent range. In addition, the main component in the present invention is a component that is contained in the largest amount, and is usually a component that is 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more. .

  In the present invention, unless otherwise specified, the state before foaming is referred to as a molded body, and the state after foaming is referred to as a foam to distinguish them.

The method for producing a foam of the present invention contains, as main components, the component (a) and the component (b) in a mass ratio (a) / (b) = 97/3 to 60/40, and ( b) a step of obtaining a molded product obtained by controlling the average size of the components to 5 μm or less; a step of impregnating the molded product with a pressurized gas; and a molded product containing the pressurized gas. And foaming in a temperature range where the elastic modulus is 5.0 × 10 ⁸ Pa or less.

  As the first step of the method for producing a foam of the present invention, as a main component, the component (a) and the component (b) are contained in a mass ratio (a) / (b) = 97 / 3-60 / 40. In addition, it is important to obtain a molded article obtained by controlling the average size of the component (b) to 5 μm or less.

  In addition, the component (a) and the component (b) in the present invention can be used without particular limitation as long as the above requirements are satisfied. Examples of the component (a) and component (b) used in the present invention include a copolymer of the component (a) and the component (b), and a blend or alloy of the component (a) and the component (b). Is mentioned. These may be used alone or in combination of two or more.

Examples of the copolymer of the component (a) and the component (b) include an alternating copolymer of the component (a) and the component (b), a random copolymer, a block copolymer, and a graft copolymer. is there. As a copolymerization form suitable for the present invention, a block copolymer and a graft copolymer are preferred because the higher order structure (morphology) composed of the components (a) and (b) has a good phase separation structure. And a random copolymer having a high block property.
Examples of the copolymer used in the present invention include a copolymer of propylene and an α-olefin such as ethylene, butene and hexene, ethylene and propylene, butene-1, pentene-1, hexene-1, heptene-1, Α-olefins having 3 to 10 carbon atoms such as octene-1; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate; conjugation A copolymer of one or two or more comonomers selected from unsaturated compounds such as dienes and non-conjugated dienes or a multi-component copolymer, a copolymer of styrene and isobutylene, butadiene and isobutene, Acrylonitrile-butadiene-styrene copolymer, ethylene and methyl methacrylate, ethyl acetate Acrylate, butyl methacrylate, butyl acrylate, copolymer of vinyl fluoride, copolymer of propylene and methyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, copolymer of methyl methacrylate and butyl methacrylate, dimethylsiloxane An isobutene copolymer, a propylene oxide-polybutadiene copolymer, a polysulfone-polydimethylsiloxane copolymer, or the like can be used.

  The method for producing the copolymer is not particularly limited, and a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method, a bulk polymerization method using a radical initiator, and the like can be applied.

  As a blend or alloy of the component (a) and the component (b), particularly if it is composed of the component (a) and the component (b) and the average size of the component (b) can be controlled to 5 μm or less. Can be used without restriction. By controlling the average size of the component (b) of the molded body to 5 μm or less, a foam having a dense and fine foam structure can be obtained.

  As a blend or alloy of (a) component and (b) component, for example, (a) component, (b) component is a combination of crystalline thermoplastic resins, (a) component is a crystalline thermoplastic resin, (B) component is a combination of amorphous thermoplastic resins, (a) component is an amorphous thermoplastic resin, (b) component is a combination of crystalline thermoplastic resins, (a) component, (b) component Both include a combination of amorphous thermoplastic resins. The non-crystalline thermoplastic resin as used herein refers to a thermoplastic resin having a characteristic that it softens when heated and solidifies when cooled, or it cannot be in a crystalline state or has a heat of crystal melting of 10 J / g or less even when crystallized. A thermoplastic resin having a very low crystallinity.

  Examples of the crystalline thermoplastic resin include polyethylene, polypropylene, ionomer, polyethylene terephthalate, polyamide, polyacetal, polybutylene terephthalate, ultrahigh molecular weight polyethylene, polyphenylene sulfide, polyether ether ketone, polytetrafluoroethylene, or a copolymer thereof. Etc.

  Amorphous thermoplastic resins include polystyrene, rubber reinforced polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-methyl acrylate copolymer, styrene-methyl methacrylate-butadiene copolymer, polycarbonate , Polymethyl acrylate, polymethyl methacrylate, polylactic acid, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-ethylene copolymer, vinyl chloride-vinyl acetate copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene / Butylene-styrene copolymer, polybutadiene, polyisoprene, polychloroprene, styrene-butadiene copolymer, ethylene-α-olefin copolymer, ethylene-propylene-diene copolymer, cycloolefin Emissions, ethylene - tetracyclododecene copolymer, polysulfone, polyether sulfone, polyphenylene oxide, polyvinyl acetate, polyphenylene ether, a liquid crystal thermoplastic resin.

  It is important that the mass ratio of the component (a) to the component (b) is in the range of (a) / (b) = 97/3 to 60/40. The component (a) in the present invention mainly serves as a support for stabilizing the porous structure of the foam, and the component (b) is a starting point when foaming is mainly performed by impregnating a pressurized gas. And plays a role in forming a foamed region. From this viewpoint, it is preferable that the (a) component forms a matrix and the (b) component has a higher order structure (morphology) forming a domain. Furthermore, the range of (a) / (b) = 95/5 to 70/30 is preferable, and the range of 90/10 to 75/25 is particularly preferable.

  Examples of the structure composed of the component (a) and the component (b) include “sphere structure”, “cylinder structure”, “lamella structure”, etc. In the present invention, the average size of the component (b) Any structure may be used as long as it can be controlled to 5 μm or less. The average size in the present invention is the average particle diameter in the case of “spherical structure”, the average particle diameter in the minor axis direction in the case of “cylinder structure”, and the average of the lamellar thickness in the case of “lamella structure”. Points to the value. The most preferable structure of the component (b) in the present invention is a “spherical structure”. By setting the component (b) to “spherical structure”, a foam having a highly independent foam structure can be obtained.

  In the present invention, a foam having a dense and fine foam structure can be obtained by controlling the average size of the component (b) to 5 μm or less. The component (b) in the present invention serves as a starting point for foaming by impregnating a pressurized gas, and mainly plays a role in forming a foaming region. Therefore, the average size of the component (b) is controlled to 5 μm or less. Thus, the bubble diameter of the foam can be controlled in consideration of the expansion ratio. For example, if the expansion ratio is about 1.5 times, the average cell diameter of the foam is 7.5 μm, and if the expansion ratio is about 2 times, the average cell diameter of the foam can be about 10 μm. Conceivable.

  Next, the manufacturing method of a molded object is demonstrated. As the method for producing the molded body, known methods such as injection molding, profile extrusion, press molding, extrusion casting using T-die, calendar method, inflation method, etc. can be employed, and are not particularly limited. However, the extrusion casting method using a T-die is preferable from the viewpoint of film forming property and stable productivity of the molded body. The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the flow characteristics and film-forming properties of the composition, but is generally in the range of the flow start temperature of each component, preferably the flow start temperature of each component + 20 ° C or higher. Is preferred. In addition, the cooling method at the time of forming the sheet is not particularly limited. However, since the crystallinity of the formed sheet affects the porous structure distribution, the sheet is preferably cooled as quickly as possible. The casting temperature in the casting method is preferably in the range of the glass transition temperature ± 10 ° C. of each component.

  Moreover, the thickness of the molded body comprising the component (a) and the component (b) is preferably 50 μm or more. If the thickness of the molded body comprising the component (a) and the component (b) is 50 μm or more, the impregnated pressurized gas diffuses from the surface of the molded body during the process of heating the molded body containing the pressurized gas. And a good porous structure can be expressed and productivity is also good. Moreover, although the thickness of a molded object is based also on the shape of a molded object, 10 mm or less is suitable. If the thickness of the molded body is 10 mm or less, the holding time when the pressurized gas is contained is not excessive, which is advantageous in terms of production cost. In addition, when a molded object is a sheet shape, the thickness of a molded object has good 500 micrometers or less.

  As a next step, the obtained molded body is impregnated with a pressurized gas. The impregnation referred to in this step means, for example, the same state as when the pressurized gas is dissolved in the molded body. The impregnation conditions depend on the components constituting the molded body, but are not particularly limited as long as the pressurized gas can be impregnated. A specific method for impregnating the molded body with the pressurized gas may be in accordance with a known method. For example, the compact is placed in a pressure-resistant container such as an autoclave, and the compact and a gaseous or liquid gas are enclosed. Next, a batch processing method for increasing the pressure in the pressure vessel, a method in which a resin molded body is introduced into a processing zone of a pressurized gas and continuously processed, or the like can be adopted.

  The pressurized gas that can be used in the present invention is not limited to the following, but for example, carbon dioxide, nitrogen, helium, argon, nitrous oxide, ethylene, ethane, tetrafluoroethylene, perfluoroethane, tetra Fluoromethane, trifluoromethane, 1,1-difluoroethylene, trifluoroamide oxide, cis-difluorodiamine, trans-difluorodiamine, nitrogen difluoride, tritiated phosphorus, dinitrogen tetrafluoride, ozone, phosphine, nitrosyl Fluoride, nitrogen trifluoride, deuterium chloride, xenon, sulfur hexafluoride, fluoromethane, pentafluoroethane, 1,1-difluoroethene, diborane, water, tetrafluorohydrazine, silane, silicon tetrafluoride, tetrahydrogen Germanium fluoride, boron trifluoride, carbon fluoride fluoride , Chlorotrifluoromethane, bromotrifluoromethane and vinyl fluoride, and the like.

  Among these, preferred pressurized gases include carbon dioxide, nitrogen, nitrous oxide, ethylene, ethane, tetrafluoroethylene, perfluoroethane, tetrafluoromethane, trifluoromethane, and 1,1-difluoroethylene.

  Of these, carbon dioxide, nitrogen, helium, and argon, which are inert gases, are nonflammable and are preferable. Further, carbon dioxide and nitrogen are more preferable from the viewpoint of non-toxicity, low cost, and non-reactivity with most resin compositions, and carbon dioxide having a relatively high solubility in the resin composition is particularly preferable.

  The time for impregnating the pressurized gas varies depending on the composition of component (a) and component (b), and / or the mixing ratio, the thickness of the molded article, etc. More preferably, it is 30 minutes or more. If it is less than 5 minutes, there may be a case where the central part of the molded body cannot be sufficiently impregnated due to the diffusion of the pressurized gas to the molded body. The upper limit is influenced by the impregnation temperature of the pressurized gas and / or the contained pressure, but is 48 hours or less, preferably 24 hours or less, more preferably 12 hours or less from the viewpoint of production efficiency.

As the next step, the molded body is released from the pressurized gas, and the molded body impregnated with the pressurized gas is foamed. In this step, it is important that foaming is performed in a temperature range where the elastic modulus of the molded body is 5.0 × 10 ⁸ Pa or less. The elastic modulus of the molded product referred to here is storage elasticity measured at a frequency of 10 Hz and a strain of 0.1% by dynamic viscoelasticity measurement of the molded product before impregnation with pressurized gas according to JIS K-7198 A method. Point to the rate. By foaming in the temperature range in which the elastic modulus of the molded body is in such a range, a dense and fine porous structure reflecting the higher-order structure (morphology) of the component (a) and the component (b) before foaming is achieved. The foam which has can be obtained. Particularly preferable conditions for reflecting the higher-order structure (morphology) of the component (a) and the component (b) are in a temperature range where the elastic modulus of the molded body is 2.0 × 10 ⁸ Pa to 1.0 × 10 ⁷ Pa. is there.

  Furthermore, it is preferable that the value of the elastic modulus in the foaming temperature range of the component (a) and the component (b) is higher in the component (a) than in the component (b). As described above, the component (a) in the present invention serves as a support for stabilizing the porous structure of the foam, and the component (b) serves as a starting point for foaming by impregnating the pressurized gas. Mainly plays a role to form. If the relationship between the elastic modulus of the component (a) and the component (b) in the foaming temperature range is higher, the component (b) is preferably foamed at the time of foaming. Further, the ratio is more preferably 10 times or more, particularly preferably 50 times or more.

Next, in the present invention, a particularly preferable molded body is a blend or alloy in which the component (a) is a crystalline resin, the component (b) is an amorphous resin, and the melting point Tma of the component (a) (B) It is a molded article in which the glass transition temperature Tgb of the component satisfies the following formula (1).
Tma> Tgb (1)

In general, the change in elastic modulus associated with the glass transition of the amorphous resin is about 100 times, the change in elastic modulus associated with the glass transition of the crystalline resin is about 10 times or less, and around the crystal melting temperature. The change in elastic modulus is about 100 times or more.
Here, (a) component is a crystalline resin, (b) component is a non-crystalline resin blend or alloy, (a) melting point Tma of component and (b) component glass transition temperature Tgb, If Tma> Tgb, and if the molded component (a) is crystallized, the component (a) has a higher elastic modulus than the component (b) in the foaming temperature range, and has a porous structure. Since the elastic modulus of the component (b) is lower than that of the component (a), the component (b) can be mainly foamed. Moreover, since it becomes possible to adjust the elastic modulus in the temperature range from the glass transition temperature Tgb of the component (b) to the crystal melting temperature Tma of the component (a), it is possible to widen the preferable temperature range of the elastic modulus region. Therefore, it is preferable. The melting point Tma of the component (a) is preferably in the range of 40 ° C to 200 ° C, and the glass transition temperature Tgb of the component (b) is preferably in the range of -100 ° C to 200 ° C. Further, the difference (Tma−Tgb) between the melting point Tma of the component (a) and the glass transition temperature Tgb of the component (b) is preferably 10 ° C. or higher, more preferably 30 ° C. or higher, and particularly preferably 50 ° C. or higher. The upper limit is generally 200 ° C. or lower.
On the other hand, when the component (a) is not crystallized, the temperature is higher than the glass transition temperature Tgb of the component (b), and the elastic modulus of the component (a) is higher than the elastic modulus of the component (b). By foaming and then crystallizing, it is possible to obtain a foam having a low foaming temperature and heat resistance.

  The foaming method is not particularly limited as long as the foaming temperature satisfies the above range, creating a non-equilibrium state by foaming by reducing the pressure when the molded body is released from the pressurized gas, A non-equilibrium state is created by heating the molded body containing the pressurized gas under non-pressurization by releasing the molded body from the rapid pressure reduction method in which foaming is achieved by vaporizing the contained gas and / or pressurizing gas. Any method of a heating method of foaming by vaporizing the impregnated gas may be used.

When the rapid depressurization method is used, there is no process for reheating, and equipment for reheating is not necessary, which is preferable in terms of production cost and production process. However, due to the adiabatic expansion of the pressurized gas that accompanies the reduced pressure when being released from the pressurized gas, the temperature of the atmosphere rapidly decreases, so the elastic modulus of the molded body is 5.0 × 10 ⁸ Pa or more. It may be difficult to control the temperature range, and the pressure reduction rate needs to be adjusted.

Further, when using the heating method, it is taken out from the pressurized gas and foamed by reheating under non-pressurized, so that it is easy to control the temperature range where the elastic modulus of the molded body is 5.0 × 10 ⁸ Pa or more. This is preferable. In the heating method, if the time until heating is changed, the impregnated gas diffuses from the surface of the molded body into the atmosphere, so that the foam cell diameter and the expansion ratio of the foam obtained may change. The time from taking out the pressurized gas to heating varies depending on the glass transition temperature of the component (a) and the component (b) and / or the mixing ratio of the component (a) and the component (b), the thickness of the molded body, and the like. Therefore, although it cannot be generally stated, it is preferably within 12 hours, more preferably within 1 hour.

  As a heating means in the case of using the heating method, a known means may be used, and examples thereof include a hot air circulation heat treatment furnace, an oil bath, a molten salt bath and the like. A hot-air circulating heat treatment furnace is preferable from the viewpoint of handleability. What is necessary is just to set the time for which foaming is completed as the heating time.

  As described above, the control of the foaming temperature is difficult in the rapid decompression method, and the accuracy of the control of the foaming temperature is higher in the heating method, so that the heating method can be preferably employed from the viewpoint of expressing the desired porous structure. .

  After the foaming, it is preferable to cool in order to control to a desired porous structure. The cooling temperature varies depending on the glass transition temperature of the component (a) and the component (b) and / or the mixing ratio of the component (a) and the component (b) and the thickness of the molded body. It is preferable to cool rapidly.

  The molded body of the present invention may be a single layer, or may have a laminated structure for the purpose of imparting properties such as smoothness, heat resistance, solvent resistance, and pressure gas diffusibility to the surface of the molded body. good. In the case of a laminated structure, layers having different resin compositions and additives can be appropriately combined. Moreover, the lamination ratio of each layer can be suitably adjusted according to a use and the objective.

  Examples of the method for forming the laminate include a co-extrusion method, a method of forming a film of each layer, and then superposing and heat-sealing, a method of bonding with an adhesive, and the like.

  In the molded product of the present invention, additives such as a heat stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, a crystal nucleating agent, a colorant, an antistatic agent and an anti-hydrolysis agent are added to such an extent that the properties are not impaired. You may mix | blend various additives, such as an agent, a lubricant, a flame retardant, suitably. Moreover, you may contain another resin composition to such an extent that the property is not impaired.

  In addition, the foam of the present invention can be subjected to surface treatment such as corona treatment, printing, coating, vapor deposition, and perforation as required without departing from the scope of the present invention.

  The foam of this invention can also form a metal thin film layer in the back surface of this foam.

  The metal thin film layer can be formed by vapor-depositing a metal, and can be formed by, for example, a vacuum vapor deposition method, an ionization vapor deposition method, a sputtering method, an ion plating method, or the like. Although it can use without being restrict | limited especially as a vapor deposition metal material, Generally silver, aluminum, etc. are preferable.

  In addition, the metal thin film layer may be a metal single layer product or a laminate product, or a metal oxide single layer product or a laminate product, or a two-layer configuration of a metal single layer product and a metal oxide single layer product. . The thickness of the metal thin film layer varies depending on the material forming the layer, the layer formation, and the like, but is usually preferably in the range of 10 nm to 300 nm.

  The foam of the present invention can be coated on a metal plate or a resin plate.

  In addition, since the foam structure can be appropriately controlled within the range by controlling the higher-order structure (morphology) of the molded body, the foam of the present invention is a drug delivery system (for drug administration optimization) Reflective materials used in medical fields such as DDS) and regenerative medical engineering fields such as scaffolds (substrates that serve as cell scaffolds), liquid crystal display devices, lighting fixtures, lighting signs, etc., and low dielectric constants are required. It can be effectively used in applications such as high-strength porous materials, heat insulating materials, and cushioning materials.

  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 values and evaluation about a molded object and a foam were performed as follows.

(1) Molded body morphology observation The molded body was subjected to pre-dyeing treatment (RuO ₄ gas phase dyeing), and using a transmission electron microscope (manufactured by JEOL Ltd .: JEM-1200EX), near the center of the cross section of the obtained molded body. Observations were made.

(2) Temperature Dependence of Elastic Modulus Using a dynamic viscoelasticity measurement method described in JIS K-7198 A method, the molded body was subjected to vibration frequency using a viscoelastic spectrometer “DVA-200” manufactured by IT Measurement Co., Ltd. Measurement was performed from −100 ° C. to 300 ° C. at a heating rate of 3 ° C./min at 10 Hz and a strain of 0.1%.

(3) Foam porous structure observation The vicinity of the center of the cross section of the obtained foam was observed using a scanning electron microscope (Hitachi, Ltd .: S-4500).

Example 1
Propylene-ethylene block copolymer in which (a) component is propylene, (b) component is ethylene, and the mass ratio of propylene to ethylene is propylene / ethylene = 74/26 (“trade name: ZELAS 5063” manufactured by Nippon Polypro Co., Ltd.) ) Is melted and kneaded into a φ25 mm co-directional twin screw extruder (L / D = 40) set at an extrusion set temperature of 180 ° C. to 200 ° C., resulting in a die temperature of 200 ° C., a die width of 300 mm, and a lip gap of 1 mm. It was extruded from a T die and cast at a setting of a casting temperature of 30 ° C. to obtain a molded body 1 having a width = 250 mm and a thickness = 250 μm.
A morphological observation image near the center of the obtained molded body 1 is shown in FIG. The portion that appears black in FIG. 1 is the component (b), and the average size of the component (b) is 1.2 μm. Moreover, the temperature dependence of the elasticity modulus of the obtained molded object 1 is shown in FIG.

Next, the obtained molded body 1 was put into a pressure vessel whose temperature was adjusted to 40 ° C. (the elastic modulus at 40 ° C. of the molded body is 3.5 × 10 ⁸ Pa from FIG. 2), and carbon dioxide gas (carbon dioxide ) To 10 MPa, and the compact 1 was impregnated with carbon dioxide for 1 hour. Thereafter, the leak valve of the pressure vessel was fully opened, the pressure in the vessel was released at a pressure reduction rate of 0.5 MPa / sec, and a sheet was taken out from the vessel to obtain a foam 1.

A hole observation image near the center of the obtained foam 1 is shown in FIG. The foam 1 had an expansion ratio of about 1.5 and an average cell diameter of about 1.7 μm. Moreover, the foam 2 was obtained by the same method as above except that the temperature of the pressure vessel was 120 ° C. (the elastic modulus at 120 ° C. of the molded body was 7.5 × 10 ⁷ Pa from FIG. 2). FIG. 4 shows an observation image in the vicinity of the center of the obtained foam 2, and FIG. 5 shows an observation image after ion etching treatment after RuO ₄ gas phase staining of the obtained foam 2. In FIG. 5, the region where the component (a) is subjected to the etching process, and the portion which appears white is the region (b).
The expansion ratio of the foam 2 was about 2.1 times, and the average cell diameter was 2.5 μm. Both of the foams 1 and 2 have a cell diameter commensurate with the average size and expansion ratio of the component (b) of the molded body 1, and a foam reflecting the morphology of the molded body 1 can be obtained. I can confirm. It can also be seen that the foam 2 has a foam structure formed mainly in the region of the component (b).

(Example 2)
As component (a), polypropylene ("trade name: Novatec PP FY4" manufactured by Nippon Polypro Co., Ltd. (glass transition temperature (Tg) = -10 ° C, melting point (Tm) = 162 ° C)) 75 parts by mass, component (b) styrene -Ethylene / butylene-styrene copolymer (product name: DYNARON 9901P (styrene content = 51%, Tg = -50 ° C), manufactured by JSR Corporation) 25 parts by weight, dry-blended, the same as in Example 1 The molded body 2 was obtained by the method described above.
A morphology observation image of the molded body 2 is shown in FIG. The white line in FIG. 6 indicates a length of 500 nm. (B) The structure which the particle | grains which disperse | distributed by the nano order aggregated is formed, and it has the morphology from which the average size of the aggregated area | region will be 300-500 nm. Moreover, the temperature dependence of the elasticity modulus of the molded object 2, (a) component, and (b) component is shown in FIG.

Next, the temperature of the pressure vessel was adjusted to 20 ° C., carbon dioxide (carbon dioxide) was pressurized to 20 MPa, the impregnation time was 6 hours, the pressure reduction rate was 1 MPa / sec, and the set temperature of the hot-air circulating heat treatment furnace was 120 ° C. 7 to 120 ° C., the elastic modulus of the molded body was 1.6 × 10 ⁷ Pa), and then charged for 1 minute. After the charging, the surface was cooled with compressed air. Inventive foam 3 was obtained.
An observation image of the obtained foam 3 is shown in FIG. In addition, the expansion ratio of this foam 3 was about 1.2 times, and the average cell diameter was about 0.6 μm. It can be confirmed that a foam reflecting the morphology of the molded body 2 can be obtained because the cell diameter is commensurate with the agglomerated size and expansion ratio of the component (b) of the molded body 2.

(Comparative Example 1)
The same molded body as in Example 2 was put into a pressure vessel adjusted to 40 ° C., pressurized to 20 MPa with carbon dioxide, and after 6 hours, the pressure in the vessel was released at a pressure reduction rate of 1 MPa / sec. The molded body was taken out from the above.
Result Although it contains the component (a) and the component (b), it is in the temperature range where the elastic modulus of the molded product is 5.0 × 10 ⁸ Pa or more, so a foam cannot be obtained and impregnated with carbon dioxide. It was the same state as before.

(Example 3)
As component (a), 75 parts by mass of polypropylene (trade name: Novatec PP FY4 manufactured by Nippon Polypro Co., Ltd. (crystalline resin, glass transition temperature (Tg) = − 10 ° C., melting point (Tm) = 162 ° C.)), (b ) 25 parts by mass of a hydrogenated styrene-butadiene copolymer (“Tough Tech H1051” (amorphous resin, styrene content = 42%, Tg = −50 ° C.) manufactured by Asahi Kasei Life & Living) as a component A molded product 3 of the present invention was obtained under the same conditions as in Example 1.
A morphology observation image of the molded body 3 is shown in FIG. A white line in FIG. 9 indicates a length of 2 μm. The morphology of the molded body 3 has a sea-island structure, and the average size of the component (b) is 1.1 μm. Further, the temperature dependence of the elastic modulus of the molded body 3 is shown in FIG.

Next, a foam 4 was obtained under the same conditions as in Example 2 (the elastic modulus of the molded body at 120 ° C. was 1.6 × 10 ⁷ Pa from FIG. 10). An observation image of the obtained foam 4 is shown in FIG. In addition, the expansion ratio of this foam 4 was about 1.5 times, and the average cell diameter was about 1.8 μm. It can be confirmed that a foam reflecting the morphology of the molded body 3 can be obtained because the cell diameter is commensurate with the average size and the expansion ratio of the component (b) of the molded body 3.

(Comparative Example 2)
In Example 2, a molded body was produced using only the component (a), and the same procedure as in Example 1 was performed except that the temperature of the pressure vessel was 120 ° C.
FIG. 12 shows the temperature dependence of the elastic modulus of the obtained molded body. The result is a temperature range in which the elastic modulus of the molded product is 5.0 × 10 ⁸ Pa or less, but since it does not have the component (b), the obtained molded product is not foamed and impregnated with carbon dioxide. It was the same state as before.

Example 4
(A) 75 parts by mass of polylactic acid (product name: NatureWorks 4032D manufactured by NatureWorks) (crystalline resin, Tg = 65 ° C., Tm = 165 ° C.) as component, and silicone acrylic composite rubber (Mitsubishi Rayon Co., Ltd.) as component (b) “Product name: Methbrene S-2001” (amorphous resin, Tg = −42 ° C.)) 25 parts by mass, and the molding temperature 4 was obtained in the same manner as in Example 1 except that the casting temperature was 55 ° C. It was.
The morphology of the obtained molded body 4 has a sea-island structure, and the temperature dependency of the elastic modulus in which the size of the component (b) is 0.9 μm is shown in FIG.

Next, the pressure vessel temperature is adjusted to 20 ° C., carbon dioxide (carbon dioxide) is 20 MPa, the impregnation time is 4 hours, and the set temperature of the hot-air circulating heat treatment furnace is 70 ° C. The foam 5 of the present invention was obtained in the same manner as in Example 2 except that the rate was set to 1.7 × 10 ⁷ Pa.
The observation image of the obtained foam 5 is shown in FIG. The foaming factor of this foam 4 was about 1.4 times, and the average cell diameter was about 1.3 μm. It can be confirmed that a fine foam having an average expansion ratio of the average size of the component (b) of the molded body 4 can be obtained.

(Example 5)
(A) Polypropylene, which is a crystalline resin as a component (“trade name: Novatec PP FY4” manufactured by Nippon Polypropylene (glass transition temperature (Tg) = − 10 ° C., melting point (Tm) = 162 ° C.)), 50 parts by mass (b Example 1) What was dry-blended with 50 parts by mass of propylene-ethylene copolymer (“trade name: Prime TPO R110E (Tg = −50 ° C.)” manufactured by Idemitsu Petrochemical Co., Ltd.), which is a crystalline resin, as a component of Example 1 The molded object 5 was obtained on the conditions similar to.

  The morphology observation image of the molded body 5 is shown in FIG. 15 (the white line in FIG. 15 indicates a length of 2 μm), and the temperature dependence of the elastic modulus is shown in FIG. The molded body 5 was press-molded at 230 ° C. for 10 minutes to obtain a plate-shaped molded body 6 having a thickness of 3 mm. A morphology observation image of the molded body 6 is shown in FIG. 17 (the white line in FIG. 17 indicates a length of 2 μm).

For the molded body 5, the pressure vessel temperature was 40 ° C. (the elastic modulus of the molded body at 40 ° C. is 3.4 × 10 ⁸ Pa from FIG. 16), the impregnation pressure was 10 MPa, the impregnation time was 1 hour, and the pressure reduction rate. Was foamed at 1 MPa / sec to obtain a foam 6.
An observation image of the obtained foam 6 is shown in FIG. For the molded body 6, the pressure vessel temperature was 40 ° C. (from FIG. 16, the elastic modulus of the molded body at 40 ° C. is 3.4 × 10 ⁸ Pa), the impregnation pressure was 20 MPa, and the impregnation time was 8 hours. Carbon dioxide gas (carbon dioxide) was contained and foamed at a reduced pressure rate of 1 MPa / sec to obtain foam 7.
An observation image of the obtained foam 7 is shown in FIG. When the dispersion structure of the component (b) of the molded body changes, the foam structure also changes, and it can be confirmed that the foam structure reflects the morphology of the component (b).

(Comparative Example 3)
A propylene-ethylene random copolymer (Mitsubishi Chemical "ZELAS7053") in which the component (a) is propylene, the component (b) is ethylene, and the mass ratio of propylene to ethylene is propylene / ethylene = 90/10 was used. Except for this, a molded body 7 was obtained in the same manner as in Example 1.
The morphology of the obtained molded body 7 is shown in FIG. 20, and the temperature dependence of the elastic modulus is shown in FIG.

Next, the obtained molded body 7 was put into a pressure vessel whose temperature was adjusted to 20 ° C. (the elastic modulus of the molded body at 20 ° C. is 5.2 × 10 ⁸ Pa from FIG. 21), and the impregnation pressure was 10 MPa. The molded body was made to contain carbon dioxide (carbon dioxide) for 1 hour, and foamed by rapid decompression to obtain foam 8.
An observation image of the obtained foam 8 is shown in FIG. Although the obtained foam 8 has pores, the number is small.

(Example 6)
After using the molded body 7 obtained in Comparative Example 3 and placing it in a pressure vessel adjusted to 40 ° C., impregnation pressure was 20 MPa, impregnation time was 6 hours, and carbon dioxide gas (carbon dioxide) was contained in the molded body. Fully open the leak valve of the pressure vessel, release the pressure in the vessel at a decompression rate of 1 MPa / sec, take out the molded product from the vessel, and set the gas-impregnated molded product at 120 ° C. The foamed body 9 of the present invention was obtained by throwing it into the interior for 1 minute and then cooling the surface with compressed air after the introduction.
An observation image of the obtained foam 9 is shown in FIG. It can be confirmed that a dense and fine foam is obtained as compared with Comparative Example 3, and a dense and fine foam reflecting the morphology of the molded body can be obtained.

It can be seen that the foams obtained by the production methods of Examples 1 to 6 have a fine and dense porous structure reflecting the morphology of the molded body. Specifically, when the domain is small, the pore diameter of the obtained foam is also small, and it can be confirmed that pores corresponding to the average size and the expansion ratio of the component (b) in the molded body are formed. On the other hand, when the component (a) and the component (b) are contained, the molded article is foamed in a temperature range where the elastic modulus exceeds 5.0 × 10 ⁸ Pa (Comparative Examples 1 and 3). ), It can be confirmed that the foam cannot be obtained or the foam has a small number of pores. Moreover, although it is the temperature range from which the elasticity modulus of a molded object is set to 5.0 * 10 < ⁸ > Pa or less, even when it does not have (b) component (comparative example 2), a foam cannot be obtained.

Claims (3)

A molded product containing the components (a) and (b) as the main components and the average size of the component (b) being controlled to 5 μm or less was obtained, and the molded product was impregnated with a pressurized gas. Thereafter, foaming is performed in a temperature range where the elastic modulus of the molded body is 5.0 × 10 ⁸ Pa or less, mainly in the region of the component (b), and a sheet-shaped foaming having a thickness of 50 μm or more and 500 μm or less. body. The component (a) is a crystalline resin, the component (b) is an amorphous resin, and the melting point Tma of the component (a) and the glass transition temperature Tgb of the component (b) are the following ( The foam according to claim 1, which satisfies the formula (1).
Tma> Tgb (1) The foam according to claim 1 or 2, further comprising a metal thin film layer on the surface.