JP2008143147A - Propylene-based resin extrusion-foamed body and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propylene-based resin extrusion-foamed body having all of heat insulation, sound absorption and energy absorption. <P>SOLUTION: The propylene-based resin extrusion-foamed body is manufactured by melting and kneading a composition composed of a polypropylene-based resin and a foaming agent in an extruder and then spouting the composition to a low pressure area, and has an at least two or more multi-layered structure containing the first and second layer in the thicknesswise direction described below wherein the first layer is the polypropylene-based resin foamed body with a foaming ratio of 10 or more, and the total surface area of holes (broken cell parts) of wall cells appearing on the observation surface that is a cross section of the foamed body is less than 2% based on the total surface area of all the cells appearing on the observation surface; and the second layer is the polypropylene-based resin foamed body with a foaming ratio of 10 or more, and the total surface area of holes (broken cell parts) of wall cells appearing on the observation surface that is a cross section of the foamed body is not less than 2% based on the total surface area of all the cells appearing on the observation surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a propylene-based resin extruded foam excellent in heat insulation performance and sound absorption performance and a method for producing the same.

Conventionally, an extruded foam of a thermoplastic resin has been used. For example, an extruded foam obtained by extruding a thermoplastic resin or a die having a large number of small holes is used to extrude these thermoplastic resins, and the extruded resin strips are converged and the outer surface is fused to foam. Extruded foam strips formed by so-called strand extrusion are used.
Such extruded foams of thermoplastic resins are lightweight and excellent in mechanical properties, and are therefore widely used as structural materials in fields such as the construction / civil engineering and automobile fields. Use as a structural material with sound absorbing performance is expected. As such an extruded foam of a thermoplastic resin, an extruded foam made of a polystyrene resin is known. Further, as an extruded foam of a thermosetting resin, an extruded foam made of a polyurethane resin is also known.

Here, since polyurethane resin is a material that is not necessarily excellent in recycling characteristics, there has been a problem that it cannot sufficiently comply with the Building Recycling Law (law concerning recycling of materials related to construction work). . In addition, since polystyrene resins are inferior in heat resistance and chemical resistance, it has been desired to provide an extruded foam using a thermoplastic resin instead of them.
On the other hand, the polypropylene resin is excellent in mechanical properties, heat resistance, chemical resistance, electrical properties, etc., and is a low-cost material. Widely used in each molding field.

In such extruded foams of polypropylene-based resins, heat insulation performance and sound absorption performance superior to conventional ones are required for application in the fields of construction, civil engineering and automobiles, and various studies have been made for this purpose. ing.
For example, improvement of sound absorption performance (for example, refer to Patent Document 1), improvement by setting the cell diameter (for example, refer to Patent Document 2), insulation performance and sound absorption performance by a combination of closed cells and open cells, Improvement (for example, refer patent document 3), improvement by multilayering (for example, refer patent document 4), etc. are mentioned.

JP 2002-524635 A JP 2002-524636 A Special table 2003-528173 gazette Japanese Unexamined Patent Publication No. 7-76052

However, conventional propylene-based resin extruded foams have not always fully satisfied the required performance according to the application field, particularly the sound absorption performance and heat insulation performance, regardless of the high basic performance.
For example, in the automotive field, for comfort of living spaces, parts having excellent sound absorption characteristics on the inside and heat insulation on the outside are required as materials for ceilings, doors, floors, cowls and the like surrounding the space. Yes.
Conventionally, for parts having such characteristics, materials having sound absorption characteristics (felt, PET fiber nonwoven fabric) on the inside and foam parts such as urethane and olefin on the outside are adhered with an adhesive or the like. However, since parts are made by combining a plurality of materials, there are problems such as high cost of parts, heavy weight, poor environmental recyclability, and bulky living space.
Therefore, a material that can be integrally formed with one material in a single process and that has both heat insulating properties and sound absorbing properties is expected.
Further, in the housing equipment field, particularly in an apartment house, improvement of sound absorption characteristics has become an important requirement in order to protect not only heat insulation performance but also mutual privacy.
Conventionally, glass wool or various resin foams are used to provide heat insulation, but when sound absorption characteristics are required, it is necessary to add sound absorbing parts. For this reason, there is a problem in terms of cost, and the thickness increases to narrow the living space.
Therefore, there is a need for a heat insulating board that has an integrated and thin board and has both sound absorbing properties and heat insulating properties.

  Accordingly, an object of the present invention is to provide a propylene-based resin extruded foam having both heat insulation performance and sound absorption characteristics, and a method for producing the same.

The propylene-based resin extruded foam of the present invention is a propylene-based resin extruded foam manufactured by melt-kneading a composition comprising a polypropylene-based resin and a foaming agent in an extruder and discharging the composition to a low-pressure region, in the thickness direction. And a multilayer structure including at least two layers including the following first layer and second layer.
(First layer) With the cross-section of the foam as the observation surface, the total area of the cell wall holes (bubble breakage) appearing on this observation surface is less than 2% of the total area of all cell cross-sections appearing on the observation surface Yes, a layer made of a polypropylene resin foam having an expansion ratio of 10 times or more.
(Second layer) With the cross section of the foam as the observation surface, the total area of the cell wall holes (bubble breakage) appearing on this observation surface is 2% or more of the total area of all cell cross sections appearing on the observation surface Yes, a layer made of a polypropylene resin foam having an expansion ratio of 10 times or more.

In the present invention, for the observation surface, for example, when the foam is cut and the cross section is photographed (cross-sectional photograph), the cross section can be adopted. As long as an arbitrary section can be obtained without the actual cutting and the shape of the foamed cell projected onto the plane can be measured, various existing measuring methods can be used.
The total area of the cell wall holes (bubble breakage) appearing on the observation surface is the sum of the areas of the holes (bubble breakage) generated on the cell wall on the above-described observation surface (cross-sectional photograph, etc.). Here, the area of each hole is not the actual opening area of the cell wall, but the area when projected onto the observation surface. Therefore, the actual hole area and the area integrated on the observation surface differ depending on the generation site in the cell.
The total area of the cross-sections of all cells appearing on the observation surface is the sum of the cross-sectional areas of all the cells observed on the observation surface (cross-sectional photograph) described above.
As an observation surface, it is desirable that a large number of cells are to be observed (a large number of cells are photographed in a cross-sectional photograph), and thereby the cross-sectional area of each cell and the area of the bubble breaking part are obtained as an average value. . That is, the size of the cell to be observed, the size of the bubble breaking part, and the frequency of occurrence are biased by the part of the foam and may vary when observed on a small scale. On the other hand, the overall characteristics of the foam can be defined on average by making a large number of cells to be observed.
The use of the observation surface in the present invention is employed as a statistical means in order to define the characteristics of such foam cells that tend to vary partially. The purpose of the present invention is to appropriately adjust the physical properties of the molded foam by appropriately setting the opening ratio of the foam breakage portion generated in the foam cell to the cell cross-sectional area. It is.

In such a propylene-based resin extruded foam of the present invention, the first layer has a small area of holes generated in each cell, each cell is maintained in a closed cell state, and the expansion ratio is 10 times or more. . For this reason, a large number of independent bubbles are difficult to transfer heat and have excellent heat insulation performance. On the other hand, the second layer has a large area of holes generated in each cell and is in a state of open cells communicating with each other. For this reason, while each bubble is mutually connected and a continuous air layer is formed, since the expansion ratio is 10 times or more, the ratio of the air layer in a foam becomes high. Therefore, if such a continuous air layer communicates from the surface of the foam to the outside, the sound reaching the surface can be taken into the continuous air layer described above, and an extruded foam having excellent sound absorption performance and Become.
For this reason, the propylene-based resin extruded foam of the present invention having the first layer and the second layer as described above becomes an extruded foam excellent in heat insulation performance and sound absorption performance.
And the propylene-type resin extrusion foam of this invention makes a foam light weight by making a foaming ratio 10 times or more, and will also be excellent in handleability.
In addition, in this invention, it is desirable for the 2nd layer which ensures sound absorption performance to be located in the surface of a propylene-type resin extrusion foam. However, even if there is another surface layer, if the surface layer has a function of transmitting sound (a material that can transmit holes, openings, or sound), the same sound absorbing performance as that on the surface should be secured. Is also possible.

In the propylene-based resin extruded foam of the present invention, the cell wall having an area of 1 × 10 ⁻⁵ mm ² or more in the hole (breaking part) of the cell wall on the observation surface of the foam of the second layer. It is desirable that the total area of the holes (bubble breaking portions) is 2% or more of the total area of the cross sections of all cells appearing on the observation surface.
With such a configuration, an opening area sufficient for transmitting sound is secured, and it is effective for improving sound absorption performance by open cells.

In the propylene-based resin extruded foam of the present invention, it is desirable that the foam cell of the second layer communicates with the outside air.
With such a configuration, external sound can be directly introduced into the open cell portion, which is effective in improving sound absorption performance.

In the extruded foam of the propylene-based resin of the present invention, it is desirable that the average diameter of the foam cell of the first layer is 500 μm or less.
With such a configuration, the first layer can be composed of relatively small cells, and the rigidity as a propylene-based resin extruded foam can be increased by such a first layer.
Furthermore, since the cell becomes small, a large number of bubble walls in the extruded foam can be formed, so that it is possible to efficiently block radiant heat from the outside. As a result, it is possible to provide an extruded foam having further excellent heat insulation performance.
In addition, it is more preferable that the average diameter of the foamed cells constituting the first layer is 200 μm or less, whereby the above-described effects can be enjoyed more efficiently.

In the propylene-based resin extruded foam of the present invention, it is desirable that the foam cell of the second layer has an average diameter of 100 μm or more and 5 mm or less.
With such a configuration, the second layer can be composed of relatively large cells, and the volume when each cell is continued can be further increased, which is effective in improving sound absorption performance due to open cells.

In the propylene-based resin extruded foam of the present invention, the extruded extruded foam bundle is produced by discharging a large number of strips simultaneously from one or more dies, and then bundling a large number of these strips. Is desirable.
According to such a configuration, since the propylene-based resin extruded foam is made of an extruded foamed strip bundle in which a large number of extruded foams of a strip are bundled, the foaming ratio of the extruded foam is increased. In addition, an extruded foam having a high foaming ratio and a sufficient thickness can be easily formed in various shapes.

The propylene-based resin extruded foam of the present invention is preferably an extruded foam having a portion where the strip is not formed in part.
According to such a configuration, the space formed by the portion where the strips are not formed effectively absorbs sound waves in a specific frequency region, and thus can exhibit further excellent sound absorption performance. Become. That is, since the frequency of the sound wave to be absorbed varies depending on the structure of the space, when the frequency of noise or the like to be absorbed is specified, the structure of the space is appropriately set according to the specified frequency. If determined, the sound absorption characteristics can be exhibited efficiently.

In the propylene-based resin extruded foam of the present invention, the propylene-based resin constituting the first layer and the second layer is preferably a propylene-based multistage polymer composed of the following components (A) and (B), respectively.
(A) Propylene homopolymer component having intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. of more than 10 dL / g, or copolymer component of propylene and α-olefin having 2 to 8 carbon atoms, total weight 5-15 mass% is contained in the coalescence.
(B) A propylene homopolymer component having a [η] of 0.5 to 3.0 dL / g measured in a tetralin solvent at 135 ° C. or a copolymer component of propylene and an α-olefin having 2 to 8 carbon atoms. Is contained in the total polymer in an amount of 85 to 95% by mass.
In such a configuration, by providing the component (A), that is, the ultrahigh molecular weight propylene polymer, a high melt tension can be achieved, and by adjusting the molecular weight distribution, the viscoelastic characteristics are adjusted, and excellent viscoelastic characteristics are obtained. The provided linear propylene polymer can be used as a main raw material. Therefore, by using such a propylene-based multistage polymer having excellent viscoelastic properties as a main constituent material, it is possible to reliably form a propylene-based resin extruded foam having an expansion ratio of 10 times or more.

このような構成においては、前述したメルトフローレート（ＭＦＲ）および溶融張力（ＭＴ）の関係によって、高倍率の発泡成形の実施が容易となり、発泡倍率を１０倍以上とした押出発泡体を容易かつ確実に得ることができる。 In the propylene-based resin extruded foam of the present invention, the propylene-based multistage polymer has a relationship between a melt flow rate (MFR) at 230 ° C. and a melt tension (MT) at 230 ° C. of the following formula (III): Is desirable.

In such a configuration, the above-described relationship between the melt flow rate (MFR) and the melt tension (MT) makes it easy to perform high-magnification foam molding, and an extruded foam with a foaming ratio of 10 times or more can be easily and You can definitely get it.

In the propylene-based resin extruded foam of the present invention, it is desirable that at least one layer or all layers contain a fibrous filler, and the content of the fibrous filler is 60% by mass or less.
In such a configuration, the fibrous filler is randomly arranged by the foam cells in the propylene-based resin extruded foam, and the fibrous filler is extruded from the propylene-based resin extruded foam in the fiber length direction. In addition to being disposed along the direction, the foam cell is disposed along the thickness direction. Thereby, even when a slight distortion occurs in the thickness direction of the propylene-based resin extruded foam, a high stress is generated, and the energy absorption capacity can be improved.

Here, the content of the fibrous filler is more than 0% by mass and not more than 60% by mass with respect to the entire molding material, and is preferably in the range of 5 to 30% by mass. If the content of the fibrous filler is less than 5 mass, it is not sufficient for improving the energy absorption capacity, and if it exceeds 30 mass%, the foam moldability may be deteriorated. Since the fibrous filler may protrude, there may be a problem that the cell structure is excessively broken and the expansion ratio is lowered.
In addition, when content of a fibrous filler exceeds 60 mass%, while foam moldability will fall, the protrusion of the fibrous filler from the wall surface of a foam cell will become remarkable, and a foaming ratio will be reduced.

In the present invention, it is preferable that 20% or more of the total number of the fibrous fillers is oriented along the thickness direction substantially orthogonal to the extrusion direction of the propylene-based resin extruded foam.
According to such a configuration, 20% or more of the fibrous filler is oriented along the thickness direction of the propylene-based resin extruded foam, so that a propylene-based resin extruded foam having a high energy absorption capability is obtained.
In the present invention, the fibrous filler disposed along the thickness direction means that the angle formed by the fiber length direction with respect to the axis in the thickness direction is not less than 0 ° (parallel to the thickness direction) and not more than 45 °. Say something.

In the propylene-based resin extruded foam of the present invention, at least one layer or all layers contain an olefin polymer, and this olefin polymer has a loss tangent (tan δ) at a temperature of 298 K and a frequency of 10 Hz of 0.04 to 0.04. 100 is desirable.
In such a configuration, an olefin polymer having a loss tangent (tan δ) at a temperature of 298 K and a frequency of 10 Hz of 0.04 to 100 or less (hereinafter referred to as “specific olefin polymer”). In some cases).
The above-mentioned specific olefin polymer is not bonded to the main constituent material propylene resin, and is therefore excluded from the crystal of polypropylene, which is a crystalline polymer. The specific olefin polymer that is a viscous substance is uniformly present on the surface of the cell).
In other words, the propylene-based resin that is a rigid part has a property of propagating energy, whereas a substance having a viscosity near room temperature (a specific olefin polymer) uses vibration energy as thermal energy of internal molecular motion. Therefore, it has the property of absorbing vibration energy. In order to absorb vibration, it is desirable to uniformly disperse the adhesive substance on the vibration surface. The specific olefin polymer having a molecular structure close to that of the polypropylene resin on the vibration surface is a polypropylene resin. Therefore, it is uniformly dispersed on the surface of the cell wall and efficiently absorbs vibration, and an extruded foam excellent in vibration damping performance can be provided.

In such a configuration, the weight ratio (a / b) of the specific olefin polymer (a) and the propylene resin (b) is preferably 1/100 to 80/100.
In such a configuration, a foam molding made of a polypropylene resin is included by including a specific olefin polymer so that the weight ratio (a / b) is 1/100 to 80/100 with respect to the constituent materials. In the body, the olefin polymer is moderately dispersed on the wall surface of the foam cell, and the vibration damping performance can be improved.
In the present invention, as the olefin polymer, it is preferable to use the 1-butene copolymer of the following first or second embodiment, and by using such a 1-butene polymer. The vibration damping performance can be reliably imparted to the extruded foam.
1st aspect: 1-butene type polymer which comprises the requirements of following (1)-(3).
(1) Intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. is 0.01 to 0.5 dL / g
(2) Using a differential scanning calorimeter (DSC), hold the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then raise the temperature at 10 ° C./min. Crystalline resin (3) Stereoregularity index {(mmmm) / (mmrr + rmmr)} having a melting point ( _Tm- D) defined as the peak top of the observed peak of 0 to 100 ° C. is 30 or less Second aspect: A 1-butene polymer comprising the following (1), (2) and (3 ′).
(1 ′) Intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. is 0.25 to 0.5 dL / g
(2) Using a differential scanning calorimeter (DSC), hold the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then raise the temperature at 10 ° C./min. Mesopentad fraction (mmmm) determined from a crystalline resin (3 ′) ¹³ C-nuclear magnetic resonance (NMR) spectrum having a melting point (T _m -D) defined as the peak top of the observed peak of 0 to 100 ° C. Is less than 73%

The process for producing a propylene-based resin extruded foam according to the present invention comprises a composition comprising a polypropylene-based resin and a foaming agent, melt-kneaded in an extruder, and discharged to a low-pressure region to extrude a propylene-based resin having at least two layers. A method for producing a propylene-based resin extruded foam for producing a foam,
A die in which a first extrusion hole having a diameter of 0.2 to 2 mm and a second extrusion hole having a diameter 1.1 times or more that of the first extrusion hole are arranged in layers on the die of the extruder. Use
The foam extruded from each extrusion hole of the die is converged in a layer shape, and formed into a plate shape having a multilayer structure.
In such a structure, the manufacturing method suitable for manufacture of the propylene-type resin extrusion foam of this invention mentioned above can be provided.
That is, the strips extruded from the first extrusion holes are converged to form the first layer described above, and the strips extruded from the second extrusion hole are converged to form the second layer described above. Here, by setting the first extrusion hole to have a diameter of 0.2 to 2 mm, it is possible to form a strip having few cell holes (foaming part) suitable for the first layer, and to form the second extrusion hole with the first extrusion hole. By setting it to 1.1 times or more of one extrusion hole, it is possible to form a strip with many cell holes (bubble breakage) suitable for the second layer. The numerical range of the diameter of the first extrusion hole (diameter 0.2 to 2 mm) may include the diameter of the second extrusion hole (1.1 times the diameter of the first extrusion hole). This is because the bubble breaking size of the bubble breaking portion varies depending on the extrusion hole diameter and the extrusion pressure. When extruded at the same extrusion pressure, the second layer can be formed with a diameter of 1.1 times or more the extrusion hole diameter of the production conditions of the first layer.
Therefore, the propylene-based resin extruded foam of the present invention described above can be efficiently manufactured by using the extruder having such a configuration.
As for the structure of the die, if the propylene-based resin extruded foam to be produced is a two-layer laminate, the first extrusion hole and the second extrusion hole described above are also arranged in two layers. Can be. On the other hand, when the propylene-based resin extruded foam to be manufactured is a laminate of three or more layers, a die in which three or more extrusion holes including the first and second extrusion holes described above are arranged may be used.
The extrusion holes of the plurality of layers may be formed in one die, but a plurality of dies having each extrusion hole may be used in combination.

In the method for producing a propylene-based resin extruded foam of the present invention, a plurality of dies including a die formed with the first extrusion hole and a die formed with the second extrusion hole are used. It is desirable to focus the foam extruded from the holes in layers.
In installing a plurality of dies, it is possible to install a plurality of dies in the extruder, and a plurality of appropriately selected dies may be installed in the extruder, or a plurality of dies each having one die installed. It is good also as a structure which bundles the strip extruded from each using an extruder.
In such a configuration, if extrusion holes set in advance to various diameters are formed as a plurality of dies, dies having extrusion holes under desired conditions can be selected as appropriate, and various combinations of these dies can be used. A propylene-based resin extruded foam having a layer structure can be produced.

In the method for producing a propylene-based resin extruded foam of the present invention, after forming a plate-like extruded foam having a multilayer structure, a hole is made in the skin portion with one or more needle-like bodies to open some foamed cells to the outside air. It is desirable to communicate.
According to such a configuration, the space formed by the open cell structure inside the foam communicates with the outside air, and the sound absorption performance is improved by efficiently absorbing sound waves from the outside into the space inside the foam. Will improve.
As a method of making a hole in the skin part of the sound absorbing layer with a needle-like body, when cooling and shaping the extruded foam, a large number of needle-like bodies are used to form the foam when the foam enters the sizing device. A sizing device can be used in which holes are formed and these needles move together with the surface of the foamed molded product. The hole size is preferably in the range of 0.1 mm to 3 mm. Depending on the size of the hole (diameter, depth, volume, etc.), the frequency of the sound wave that is absorbed varies. For this reason, when the frequency of the noise to be absorbed is specified, the diameter, depth, and internal shape of the hole can be optimized so that the sound wave of this specific frequency is most effectively absorbed.

In the method for producing a propylene-based resin extruded foam according to the present invention, after forming a plate-like extruded foam having a multilayer structure, the skin portion may be cut to allow some foamed cells to communicate with the outside air.
Even with such a configuration, the space formed by the open cell structure inside the foam communicates with the outside air, and the sound absorption performance is improved by efficiently absorbing the sound waves from the outside into the space inside the foam. Will do.
As a method of cutting the skin portion of the sound absorbing layer, cutting may be performed using a cutting blade or the like in the latter half of the foaming extrusion process, or secondary processing may be performed again after molding to cut the surface portion. Good.

First, a first embodiment of the present invention will be described based on the drawings.
[First embodiment]
In FIG. 1, a propylene-based resin extruded foam 1 of the present invention (hereinafter sometimes referred to as “extruded foam 1”) has a two-layer laminated structure having a first layer 2 and a second layer 3. Yes.
Among these, the first layer 2 is formed with a relatively small bubble breaking portion (a hole in the cell wall) in the foam cell 21 and a small cell diameter (see FIG. 2), and is a layer excellent in rigidity and heat insulation performance. ing. The second layer 3 has a relatively large number of bubble breaking portions (holes in the cell wall) in the foamed cells 31, each cell 31 is connected to be an open cell, and a large cell diameter is formed (see FIG. 3). It is a layer with excellent sound absorption performance.

Note that the first layer 2 and the second layer 3 of the present embodiment are formed as extruded foam strip converging bodies obtained by converging the strips 22 and 32 obtained by extrusion foaming a propylene-based resin from a die, respectively. ing.
In addition, the first layer 2 and the second layer 3 of the present embodiment are improved in energy absorption performance when a fibrous filler 9 is mixed in a propylene-based resin and subjected to an impact. The fibrous filler 9 is not essential to the present invention and may be omitted as appropriate.
Due to the laminated structure including the first layer 2 and the second layer 3, the propylene-based resin extruded foam 1 of the present embodiment is an extruded foam that is lightweight and has both heat insulating properties and sound absorbing performance.

Here, the extruded foam 1 of the present invention has both heat insulation performance and sound absorption performance for the following reason.
The heat insulation performance of the extruded foam depends on the expansion ratio and the closed cell ratio at a certain expansion ratio (for example, 10 times or more). That is, when the expansion ratio is increased, the proportion of air that is excellent in heat insulation increases, so that the higher the expansion ratio, the better the heat insulation performance. On the other hand, a hole (breaking part) is generated in the cell wall of the foam cell, but each cell can be made into an independent cell by reducing the number of the breaking part. That is, even if the bubble-breaking portion cannot be completely eliminated, it can be handled as a closed cell if it is below a certain standard. When such a closed cell ratio is high, a large number of independent bubbles make it difficult to transfer heat, and thus an extruded foam having excellent heat insulation performance is obtained.
In the extruded foam 1 of the present invention, the first layer 2 has the cross section of the foam as the observation surface, and the total area of the holes (bubble breakage) in the cell wall that appears on this observation surface is the observation surface. By making it a layer made of a polypropylene resin foam that is less than 2% of the total area of the cross section of all the cells that appear and the foaming ratio is 10 times or more, a large number of independent bubbles make it difficult to conduct heat. An extruded foam with excellent performance. Furthermore, mechanical strength such as impact strength and moisture resistance are also excellent.

  In addition, the heat insulating performance of the extruded foam also depends on the average diameter (average cell diameter) of the foam cells constituting the foam under the above conditions. In other words, if the average diameter is reduced at the same expansion ratio, the number of bubble walls that block radiant heat increases and heat transfer becomes difficult, and heat insulation is improved. Therefore, it is preferable that the average diameter (average cell diameter) of the foamed cells is small. . In the extruded foam 1 of the present invention, by setting the average diameter of the foamed cells 21 constituting the first layer 2 to 500 μm or less, a large number of bubble walls in the extruded foam can be formed, and from the outside It is possible to efficiently block the radiant heat. The average diameter of the foam cells 21 constituting the first layer 2 is more preferably 200 μm or less.

  The sound absorption performance of the extruded foam is affected by the open cell structure and expansion ratio of the extruded foam. That is, in the extruded foam, the foam is broken to produce the above-described bubble breaking portion. Each cell is connected by such a bubble-breaking part, and the continuous air layer connected between bubbles is formed. In such a continuous space, it is known that sound waves introduced into the space are absorbed by the surrounding wall surface, and as a result, the sound absorption performance is improved. Therefore, an extruded foam having an excellent sound absorbing performance can be obtained by forming a foamed article having an open cell structure having a large cell wall hole (foam breaking part) and a low closed cell ratio (not a closed cell structure). Become. Furthermore, since sound waves are absorbed by the air layer in the foam, the sound absorption characteristics are improved by increasing the ratio of the air layer, that is, by increasing the expansion ratio.

Extruded foam 1 of the present invention has the second layer 3 as the observation surface of the cross section of the foam, and the total area of the cell wall holes (bubble breakage) appearing on this observation surface is the entire cell appearing on the observation surface. 2% or more of the total area of the cross section of the above, and the second layer 3 is an open cell in which the bubble breaking state is appropriately formed by using a layer made of a polypropylene resin foam having an expansion ratio of 10 times or more By having a structure and setting the expansion ratio to 10 times or more, the individual bubbles of the foam are provided with sound absorption characteristics, so that the extruded foam has excellent sound absorption characteristics. In addition, in the cell wall hole (bubble breaking portion) on the observation surface of the foam of the second layer 3, the total area of the cell wall hole (bubble breaking portion) having an area of 1 × 10 ⁻⁵ mm ² or more. Is more preferably 2% or more of the total area of the cross sections of all the cells on the observation surface.

  Further, the second layer 3 can form more bubble walls in the second layer 3 if the average diameter of the foam cells constituting the foam is 100 μm or more and 5 mm or less. The viscous dissipation of the vibration energy of sound due to the viscous friction of air can be efficiently performed, and the sound absorption characteristics of the extruded foam 1 can be improved.

The molding material constituting the extruded foam 1 (the first layer 2 and the second layer 3) contains a fibrous filler 9 whose content exceeds 0% by mass and equal to or less than 60% by mass with respect to the entire molding material. . Since this fibrous filler 9 will be arrange | positioned at random by the foam cell 21 and 31 in the 1st layer 2 and the 2nd layer 3, as a result, the energy absorption capability will be excellent.
By adopting such a configuration, the extruded foam 1 of the present invention becomes an extruded foam having energy absorption performance in addition to the above-described heat insulation performance and sound absorption performance.
Hereinafter, the molding material constituting the extruded foam 1 (the first layer 2 and the second layer 3) will be described.

(1) Propylene-based resin constituting the extruded foam 1:
Examples of the propylene resin used as a molding material for forming the extruded foam 1 of the present invention having such a configuration include a propylene resin having a high melt tension at the time of melting, such as JP-A-10-279632 and JP-A-10-279632. The propylene-type resin as described in 2000-309670, Unexamined-Japanese-Patent No. 2000-336198, Unexamined-Japanese-Patent No. 2002-12717, Special Table 2002-542360, Special Table 2002-509575, etc. can be used.

In order to obtain the extruded foam 1 of the present invention, as described above, it is desirable to increase the melt tension at the time of melting as the propylene-based resin, and it is preferable to use a resin material having excellent viscoelastic properties. .
As such a propylene-based resin having excellent viscoelastic properties, for example, a propylene-based multistage polymer composed of the following component (A) and component (B) is preferable as the propylene-based resin constituting the foam.
(A) A propylene homopolymer component having an intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. of more than 10 dL / g or a copolymer component of propylene and an α-olefin having 2 to 8 carbon atoms, (B) 135 ° C. contained in the polymer at 5 to 15% by mass, propylene homopolymer component having intrinsic viscosity [η] measured in tetralin solvent of 0.5 to 3.0 dL / g or propylene and carbon number The copolymer component with 2-8 alpha olefins is contained in 85-95 mass% in all the polymers.

The propylene-based multistage polymer comprising such component (A) and component (B) achieves high melt tension by applying component (A), that is, ultrahigh molecular weight propylene-based polymer, and component (B ) And a linear propylene polymer whose viscoelastic properties are adjusted by adjusting the molecular weight distribution. By using such a propylene-based multistage polymer having excellent viscoelastic properties as a constituent material, the propylene-based resin extruded foam having the requirements for the first layer 2 and the second layer 3 of the present invention described above can be reliably obtained. Can get to.
The excellent viscoelastic property is different depending on the resin material to be used, but refers to a resin material that undergoes large deformation under high-speed deformation at the time of bubble formation and moderately fast stress relaxation thereafter. When the stress relaxation is slow, the structure of the extruded foam after foam breaking cannot be maintained due to residual stress.

Here, when the intrinsic viscosity of the component (A) is 10 dL / g or less, the melt tension becomes insufficient and the desired foaming performance may not be obtained.
On the other hand, if the mass fraction of component (A) is less than 5% by mass, the melt tension becomes insufficient and the desired foaming performance may not be obtained. On the other hand, if the mass fraction exceeds 20% by mass. In other words, so-called melt fracture may become intense, which causes rough skin of the extruded foam and the product quality deteriorates.

As described above, the intrinsic viscosity of the component (A) is preferably more than 10 dL / g, more preferably in the range of 12 to 20 dL / g, and in the range of 13 to 18 dL / g. Is particularly preferred.
Moreover, it is preferable that the mass fraction of a component (A) exists in the range of 8-18 mass%, and it is especially preferable that it exists in the range of 10-18 mass%.

If the intrinsic viscosity of the component (B) is less than 0.5 dL / g, the melt tension may be insufficient and the desired foaming performance may not be obtained. It may be too high to perform a suitable extrusion.
Further, when the mass fraction of the component (B) is less than 85% by mass, it may be difficult to carry out suitable extrusion molding. When the mass fraction exceeds 95% by mass, the melt tension becomes low. In some cases, it may be difficult to perform suitable extrusion.

As described above, the intrinsic viscosity of the component (B) is preferably in the range of 0.5 to 3.0 dL / g, preferably in the range of 0.8 to 2.0 dL / g. It is particularly preferable that it is in the range of 1.0 to 1.5 dL / g.
Moreover, it is preferable that the mass fraction of a component (B) exists in the range of 87-92 mass%, and it is especially preferable that it exists in the range of 87-90 mass%.

  In the propylene-based multistage polymer, examples of the α-olefin having 2 to 8 carbon atoms constituting the copolymer component include ethylene and 1-butene which are α-olefins other than propylene. Among these, it is preferable to use ethylene.

  The propylene-based multistage polymer preferably has a melt flow rate (MFR) at 230 ° C. of 100 g / 10 min or less, particularly preferably 20 g / 10 min or less. If the MFR exceeds 100 g / 10 min, the melt tension and viscosity of the multistage polymer become low, and molding may be difficult.

  In the propylene-based multistage polymer, the relationship between the melt flow rate (MFR) at 230 ° C. and the melt tension (MT) at 230 ° C. preferably includes the following formula (III).

Here, when the relationship between the melt flow rate (MFR) at 230 ° C. and the melt tension (MT) at 230 ° C. does not satisfy the formula (III), it is difficult to perform high-magnification foam molding. Thus, an extruded foam having an expansion ratio of 10 times or more may not be obtained. The constant (1.2) is preferably 1.3 or more, and particularly preferably 1.4 or more.

  In addition, what is necessary is just to make it contain 5-15 mass% of components (A) so that a propylene type multistage polymer may have the relationship of above-mentioned Formula (III).

  In addition, the propylene-based multistage polymer has a storage elastic modulus slope on a high frequency side as a certain amount or more as dynamic viscoelasticity in a molten state (relation between angular frequency ω and storage elastic modulus G ′). It is preferable that the storage elastic modulus G ′ (10) when the angular frequency is 10 rad / s and the storage elastic modulus G ′ (1) when the angular frequency is 1 rad / s. A certain G ′ (10) / G ′ (1) is preferably 2.0 or more, and particularly preferably 2.5 or more. When the ratio G ′ (10) / G ′ (1) is less than 2.0, stability may be reduced when an external change such as stretching is applied to the extruded foam.

  Similarly, the propylene-based multistage polymer preferably has a storage elastic modulus slope on the low frequency side as a dynamic viscoelasticity in a molten state having a certain amount or less, specifically, an angular frequency. Is the ratio of the storage elastic modulus G ′ (0.1) when the angular frequency is 0.1 rad / s and the storage elastic modulus G ′ (0.01) when the angular frequency is 0.01 rad / s. 0.1) / G ′ (0.01) is preferably 6.0 or less, and particularly preferably 4.0 or less. If the ratio G ′ (0.1) / G ′ (0.01) exceeds 6.0, it may be difficult to increase the expansion ratio of the extruded foam.

  Such a propylene-based multistage polymer uses an olefin polymerization catalyst composed of the following components (a) and (b) or the following components (a), (b) and (c) in a polymerization process of two or more stages. It can be produced by polymerizing propylene or copolymerizing propylene and an α-olefin having 2 to 8 carbon atoms.

(A) Solid catalyst component obtained by treating titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound with an ether compound and an electron acceptor (b) Organoaluminum compound (c) Cyclic ester compound

  Here, (a) a solid catalyst component obtained by treating titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound with an ether compound and an electron acceptor (hereinafter simply referred to as “(a) solid catalyst component”. As the organoaluminum compound for reducing titanium tetrachloride, for example, (i) alkylaluminum dihalide, specifically, methylaluminum dichloride, ethylaluminum dichloride, and n-propylaluminum dichloride (B) alkylaluminum sesquihalide, specifically, ethylaluminum sesquichloride, (ha) dialkylaluminum halide, specifically, dimethylaluminum chloride, diethylaluminum chloride, di-n-propylaluminum chloride, Fine diethylaluminum bromide, (iv) trialkyl aluminum, specifically, trimethylaluminum, triethylaluminum, and triisobutylaluminum, (v) dialkyl aluminum hydride, specifically, may be mentioned diethyl aluminum hydride and the like. Here, “alkyl” is lower alkyl such as methyl, ethyl, propyl, butyl and the like. The “halide” is chloride or bromide, and the former is particularly common.

  Further, the reduction reaction with an organoaluminum compound for obtaining titanium trichloride is usually carried out in a temperature range of −60 to 60 ° C., preferably −30 to 30 ° C. If the temperature in the reduction reaction is lower than −60 ° C., a long time is required for the reduction reaction. On the other hand, if the temperature in the reduction reaction exceeds 60 ° C., excessive reduction may occur in some cases. The reduction reaction is preferably carried out in an inert hydrocarbon solvent such as pentane, heptane, octane and decane.

In addition, it is preferable to further perform ether treatment and electron acceptor treatment on titanium trichloride obtained by reduction reaction of titanium tetrachloride with an organoaluminum compound.
Examples of the ether compound preferably used in the ether treatment of titanium trichloride include, for example, diethyl ether, di-n-propyl ether, di-n-butyl ether, diisoamyl ether, dineopentyl ether, di-n-hexyl ether, Examples include ether compounds in which each hydrocarbon residue is a chain hydrocarbon having 2 to 8 carbon atoms such as di-n-octyl ether, di-2-ethylhexyl ether, methyl-n-butyl ether and ethyl-isobutyl ether. Of these, di-n-butyl ether is particularly preferred.

As the electron acceptor used in the treatment of titanium trichloride, it is preferable to use halogen compounds of elements of Group III to Group IV and Group VIII of the Periodic Table. Specifically, titanium tetrachloride, Examples include silicon chloride, boron trifluoride, boron trichloride, antimony pentachloride, gallium trichloride, iron trichloride, tellurium dichloride, tin tetrachloride, phosphorus trichloride, phosphorus pentachloride, vanadium tetrachloride, and zirconium tetrachloride. be able to.

  When preparing the solid catalyst component (a), the treatment with the ether compound of titanium trichloride and the electron acceptor may be performed using a mixture of both treatment agents, and after the treatment with one treatment agent, the other You may make it perform the process by the processing agent of. Of these, the latter is preferred, and treatment with an electron acceptor is further preferred after ether treatment.

  Prior to treatment with the ether compound and electron acceptor, it is preferred to wash the titanium trichloride with a hydrocarbon. The above-mentioned ether treatment with titanium trichloride is carried out by bringing titanium trichloride into contact with an ether compound, and the treatment of titanium trichloride with an ether compound is carried out by bringing them into contact with each other in the presence of a diluent. Is advantageous. As such a diluent, it is preferable to use an inert hydrocarbon compound such as hexane, heptane, octane, decane, benzene and toluene. In addition, it is preferable that the process temperature in an ether process is 0-100 degreeC. Moreover, it does not restrict | limit especially about processing time, Usually, it is performed in the range of 20 minutes-5 hours.

The amount of the ether compound used is generally 0.05 to 3.0 mol, preferably 0.5 to 1.5 mol per 1 mol of titanium trichloride. If the amount of the ether compound used is less than 0.05 mol, the stereoregularity of the produced polymer cannot be sufficiently improved, which is not preferable. On the other hand, if the amount of the ether compound used exceeds 3.0 mol, the stereoregularity of the produced polymer is improved, but the yield is lowered, which is not preferable. Strictly speaking, titanium trichloride treated with an organoaluminum compound or an ether compound is a composition containing titanium trichloride as a main component.
In addition, as such a solid catalyst component (a), Solvay type titanium trichloride can be suitably used.

  What is necessary is just to use the same thing as an above-mentioned organoaluminum compound as an organoaluminum compound (b).

  Examples of the cyclic ester compound (c) include γ-lactone, δ-lactone, ε-lactone, etc., and it is preferable to use ε-lactone.

  Moreover, the olefin polymerization catalyst used for producing the propylene-based multistage polymer can be obtained by mixing the components (a) to (c) described above.

  In order to obtain a propylene-based multistage polymer, it is preferable to polymerize propylene or copolymerize propylene and an α-olefin having 2 to 8 carbon atoms in the absence of hydrogen among the two-stage polymerization methods. Here, “in the absence of hydrogen” means substantially in the absence of hydrogen, and includes not only the case where no hydrogen is present, but also the case where a very small amount of hydrogen is present (for example, about 10 molppm). . In short, even if hydrogen is contained in such an extent that the intrinsic viscosity [η] of the first-stage propylene-based polymer or propylene-based copolymer measured in a 135 ° C. tetralin solvent does not fall below 10 dL / g, It is included in the meaning of “in the presence”.

  Propylene polymerization in the absence of hydrogen or copolymerization of propylene and α-olefin to produce an ultrahigh molecular weight propylene polymer, that is, a component (A) of a propylene multistage polymer. Can do. In the absence of hydrogen, the component (A) has a raw material monomer as a polymerization temperature, preferably 20 to 80 ° C., more preferably 40 to 70 ° C., and a polymerization pressure in general, from normal pressure to 1.47 MPa, preferably 0. It is preferably produced by slurry polymerization under the condition of 39 to 1.18 MPa.

In this production method, the component (B) of the propylene-based multistage polymer is preferably produced in the second and subsequent stages.
The production conditions for component (B) are not particularly limited except that the above-described olefin polymerization catalyst is used, but the raw material monomer is preferably 20 to 80 ° C., more preferably 60 to 70 ° C. as the polymerization temperature. In general, the polymerization pressure is preferably from normal pressure to 1.47 MPa, preferably from 0.19 to 1.18 MPa, and polymerized under the presence of hydrogen as a molecular weight regulator.

  In the above-described production method, preliminary polymerization may be performed before the main polymerization. When the prepolymerization is carried out, the powder morphology can be maintained well. In general, the prepolymerization is generally a polymerization temperature, preferably 0 to 80 ° C, more preferably 10 to 60 ° C, and a polymerization amount as a solid catalyst. Preferably, 0.001 to 100 g, more preferably 0.1 to 10 g of propylene is polymerized or copolymerized with propylene and an α-olefin having 2 to 8 carbon atoms per 1 g of the component.

Further, a propylene resin as a constituent material of the extruded foam 1 is used as a propylene resin composition, and the above-described propylene multistage polymer, a melt flow rate (MFR) at 230 ° C. of 30 g / 10 min or less, and a weight You may make it contain the propylene polymer whose _Mw / _Mn which is ratio of an average molecular weight ( _Mw ) and a number average molecular weight ( _Mn ) is 5.0 or less. By blending the above-mentioned propylene-based multistage polymer and other materials to obtain a resin composition, it is possible to improve the moldability of the extruded foam, increase its functionality, reduce costs, and the like.
By using this resin composition, the extruded foam has high melt tension and excellent viscoelastic properties, and the extruded foam has high foaming ratio, good surface appearance, and stretch breakage during sheet molding. The effect of preventing can be imparted.

  In this resin composition, the weight ratio of the propylene polymer to the propylene multistage polymer is 6 times or more, more preferably 10 times or more. If the weight ratio is less than 8 times, the surface appearance of the extruded foam may be poor.

  The melt flow rate (MFR) of the propylene polymer is preferably 30 g / 10 min or less, more preferably 15 g / 10 min or less, and particularly preferably 10 g / 10 min or less. If the MFR exceeds 30 g / 10 min, molding defects of the extruded foam may occur.

The _Mw / _Mn of the propylene-based polymer is preferably 5.0 or less, and particularly preferably 4.5 or less. When _Mw / _Mn exceeds 5.0, the surface appearance of the extruded foam may be deteriorated.
The propylene polymer can be produced by a polymerization method using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.

In this resin composition, as the dynamic viscoelasticity in a molten state (relationship between the angular frequency ω and the storage elastic modulus G ′), the slope of the storage elastic modulus on the high frequency side is a certain amount or more. Moreover, it is preferable that the slope of the storage elastic modulus on the low frequency side is a certain amount or less.
Specifically, G ′ (10), which is the ratio of the storage elastic modulus G ′ (10) when the angular frequency is 10 rad / s and the storage elastic modulus G ′ (1) when the angular frequency is 1 rad / s. ) / G ′ (1) is preferably 5.0 or more, particularly preferably 5.5 or more. When G ′ (10) / G ′ (1), which is such a ratio, is smaller than 5.0, stability may be reduced when an external change such as stretching is applied to the extruded foam.

  Further, the ratio of the storage elastic modulus G ′ (0.1) when the angular frequency is 0.1 rad / s and the storage elastic modulus G ′ (0.01) when the angular frequency is 0.01 rad / s. A certain G ′ (0.1) / G ′ (0.01) is preferably 14.0 or less, and particularly preferably 12.0 or less. If the ratio G ′ (0.1) / G ′ (0.01) exceeds 14.0, it may be difficult to increase the expansion ratio of the extruded foam.

  Here, in the case where the extruded foam is stretched, it is general that components in the range of 1 to 10 s of relaxation time cause deterioration of the stretch characteristics of the extruded foam. The greater the contribution of the relaxation time in this region, the smaller the slope of the storage elastic modulus G ′ (1) near the angular frequency ω of 1 rad / s. Therefore, as an index of this inclination, if G ′ (10) / G ′ (1), which is a ratio to the storage elastic modulus G ′ (10) when the angular frequency ω is 10 rad / s, is provided, numerical simulation and experiment As a result of analysis, it was found that the smaller this value, the greater the rupture during extrusion foaming. Therefore, in the above resin composition, it is preferable that G ′ (10) / G ′ (1) is 5.0 or more.

  In addition, a certain degree of strain hardening is required for bubble breakage at the final stage of bubble growth and bubble breakage accompanying high-speed extension deformation near the die lip in extrusion foam molding, so an appropriate relaxation time region is required. Therefore, an appropriate amount of the high molecular weight component is required, and for this purpose, the storage elastic modulus G ′ in the low frequency region must be large to some extent. Therefore, as the index, the storage elastic modulus G ′ (0.1) when the angular frequency ω is 0.1 rad / s, and the storage elastic modulus G ′ (0.01 when the angular frequency is 0.01 rad / s). When G ′ (0.1) / G ′ (0.01), which is a ratio to (), is provided, from the results of numerical simulation and experimental analysis, when this value increases, the foaming ratio decreases significantly due to bubble breakage. Was found to be. Therefore, in the above resin composition, it is preferable that G ′ (0.1) / G ′ (0.01) is 14.0 or less.

  It should be noted that the propylene-based resin constituting the extruded foam 1 of the present invention including this resin composition may include an antioxidant, a neutralizing agent, a crystal as long as the effects of the present invention are not hindered, if necessary. Nucleating agents, metal deactivators, phosphorus processing stabilizers, UV absorbers, UV stabilizers, fluorescent brighteners, metal soaps, stabilizers such as antacid absorbers or crosslinking agents, chain transfer agents, nucleating agents, lubricants Additives such as plasticizers, fillers, reinforcing agents, pigments, dyes, flame retardants and antistatic agents can be added. What is necessary is just to determine the addition amount of these additives suitably according to the various characteristics and molding conditions which are requested | required of the extrusion foam to shape | mold.

  Moreover, when using the above-mentioned propylene-based multistage polymer excellent in melt viscoelasticity as a propylene-based resin, using a known melt-kneader in advance with the aforementioned additives added as necessary. You may make it shape | mold a desired extrusion foam after melt-kneading to make a pellet shape.

In the present embodiment, the propylene-based resin extruded foam 1 contains a fibrous filler 9 that exceeds 0% by mass and equal to or less than 60% by mass with respect to the entire molding material constituting the extruded foam.
Although this fibrous filler 9 is not an essential requirement for the present invention, by mixing the fibrous filler 9, in addition to improving the heat insulation performance and sound absorption performance by the first layer 2 and the second layer 3 of the present invention, energy Improvement in absorption performance can be expected.
In the extruded foam 1, when the content of the fibrous filler 9 exceeds 60% by mass, the content of the fibrous filler 9 is too large, leading to a decrease in foam moldability, and an excessive cell structure. It will break and the expansion ratio will decrease.
In addition, it is preferable that content of this fibrous filler 9 exists in the range of 5-30 mass% of the whole molding material. When the content of the fibrous filler is smaller than 5% by mass, it may be difficult to improve the energy absorption capacity. On the other hand, when the content exceeds 30% by mass, there is a problem that the foam moldability is deteriorated. It can happen. Furthermore, if the amount exceeds 30% by mass, the fibrous filler may protrude from the wall surface of the foam cell, so that in some cases, the foam structure may be destroyed excessively, resulting in a problem that the expansion ratio is reduced. It is not preferable.

Examples of the fibrous filler 9 contained in the molding material include carbon fiber, glass fiber, and other inorganic fibers (silicon carbide fiber, alumina fiber, etc.). Among these, glass fiber is preferable. Examples of the carbon fiber include cellulosic, PAN, and pitch carbon fibers.
Here, the fibrous filler 9 is usually called a fibrous shape and includes a whisker shape, for example, an average fiber length of about 0.02 to 10 mm (in the case of a whisker shape, about 0.02 to about 2.02). 0.15 mm) and an average fiber diameter of about 0.1 to 20 μm.
In addition, when using a glass fiber as the fibrous filler 9, it is preferable to use a thing with an average fiber diameter of 5 to 20 μm and an average fiber length of 0.1 to 10 mm.

Further, 20% or more of the total number of fibrous fillers 9 is oriented along the thickness direction of the extruded foam 1. Here, the fibrous filler 9 arranged along the thickness direction means that the angle formed by the fiber length direction with respect to the axis in the thickness direction is 0 ° (parallel to the thickness direction) or more and 45 ° or less. .
Such fibrous fillers 9 are randomly arranged by the foam cells 21 and 31. That is, the fibrous filler 9 is arranged not only in the fiber length direction along the extrusion direction of the extruded foam 1 but also in the thickness direction due to the presence of the foamed foam cells 21 and 31. It becomes. Thereby, even when a slight distortion occurs in the thickness direction of the extruded foam 1, a high stress is generated, and the energy absorption capability can be improved.

If it demonstrates in detail, the relationship between the stress and distortion of the propylene-type resin extrusion foam which does not contain the fibrous filler 9 will become like FIG. In FIG. 4, the hatched portion indicates the energy absorption amount, and the larger the hatched area, the higher the energy absorption capability.
On the other hand, the extruded foam 1 of the present embodiment contains a fibrous filler 9, and this fibrous filler 9 is not only oriented along the extrusion direction, but part of the fibrous filler 9 is extruded. Since it is oriented along the thickness direction of the foam 1, the relationship between stress and strain is as shown in FIG. 5.
That is, a large stress is generated with a small strain, and the area of the hatched portion in FIG. 5 is larger than the area of the hatched portion in FIG. In particular, in the extruded foam 1 of the present embodiment, the fibrous filler 9 is oriented 20% or more along the thickness direction of the extruded foam 1 and therefore has a high energy absorption capability.

(2) Production of propylene-based resin extruded foam 1:
In the production of the extruded foam 1 of the present invention, the first layer 2 and the second layer 3 can be obtained, for example, by extruding and foaming a molding material made of the propylene-based resin described above.
As a manufacturing apparatus for the first layer 2 and the second layer 3, a molding material containing a fibrous filler 9 and a propylene resin is heated to a molten state and kneaded while applying an appropriate shear stress. A known extrusion foam molding apparatus capable of extrusion foaming can be used. Moreover, the extruder which comprises a manufacturing apparatus can also employ | adopt any of a single screw extruder or a twin screw extruder. As such an extrusion foam molding apparatus, for example, a tandem type extrusion foam molding apparatus disclosed in JP-A-2004-237729, to which two extruders are connected, may be used.

(2-1) Production of second layer 3:
When producing the second layer 3 in the extruded foam 1 of the present invention, an open cell structure (foamed structure in which a hole having an area of 2% or more is formed on the cell wall) is ensured with a high expansion ratio. To form the melt-kneaded molding material from the extrusion die, in the resin flow path near the outlet of the extrusion die, in the portion where the cross-sectional area in the direction perpendicular to the flow direction is minimized, The pressure gradient (k) represented by the following formula (I) is 50 MPa / m ≦ k ≦ 800 MPa / m, and the pressure reduction rate (v) represented by the following formula (II) is 5 MPa / s ≦ v ≦ 100 MPa / s. What should be done.

（式（Ｉ）および式（II）中、Ｍ及びｎは物質定数、Ａは押出用ダイの出口近傍の樹脂流路における、流れ方向と垂直方向の断面積が最小となる位置における当該断面積（ｍｍ^２）、Ｑはダイの出口を通過する成形材料の体積流量（ｍｍ³／ｓ）、をそれぞれ示す）

(In Formula (I) and Formula (II), M and n are material constants, A is the cross-sectional area at a position where the cross-sectional area in the direction perpendicular to the flow direction is minimum in the resin flow path near the outlet of the extrusion die. (Mm ² ), Q represents the volume flow rate (mm ³ / s) of the molding material passing through the exit of the die, respectively)

Here, forming an open cell structure, in other words, causes foam to form in the foam, but it is generally considered that the bubble breaking phenomenon occurs by the following mechanism.
In other words, in the normal bubble breaking phenomenon, when the volume fraction of the foaming gas increases during the bubble growth process, the molten resin between adjacent bubbles is locally thinned and easily deformed. As the bubble grows, local large deformation progresses and the bubble breaks between the bubbles (Phenomenon 1). After the growth of the bubble, the local thin portion between the bubbles is further increased by the residual stress due to the viscoelastic properties of the resin. Bubbles that break and break between the bubbles (Phenomenon 2), and those that undergo external deformation of the foam and selectively undergo large deformation between the thin and easily deformed bubbles (Phenomenon 3) occur almost simultaneously It is believed that.

On the other hand, in extrusion foam molding using a non-crosslinked polypropylene resin, the melt tension of the resin is insufficient, so that bubbles composed of such a resin are sufficiently grown and before the wall surface is formed and becomes stable. In addition, foam breakage due to the mechanism of phenomenon 1 described above occurred, and an extruded foam with a sufficient foaming ratio could not be obtained.
Also, if the bubbles break during the bubble growth process, a large number of bubbles are connected to form a continuous phase of gas, through which the gas escapes to the outside of the foam. It cannot be confined inside the body, and a foam with a high expansion ratio cannot be formed.

Thus, since the formation of an open cell structure in which a hole having an area of 2% or more is formed in the cell wall (formation of bubble breakage), the expansion ratio is lowered. In order to obtain an extruded foam with a high foaming ratio of 10 times or more, bubbles are prevented from being generated as much as possible until the wall surface of the extruded foam is formed, thereby preventing the gas in the extruded foam from leaking to the outside. Necessary and a sufficiently high foaming rate is being formed, or after the formation, bubbles are broken and a continuous phase is formed. At the stage where this continuous phase is formed, the framework of the extruded foam (formation of wall surface) However, it is necessary that the shape is stabilized and the gas does not escape to the outside.
Furthermore, in order to give excellent sound absorption characteristics to the extruded foam, it must have a highly foamed open cell structure (a foaming ratio of 10 times or more) in which holes with an area of 2% or more formed in the cell wall are continuously connected. I must.

For this purpose, the pressure gradient at the die outlet is set within an appropriate range so as to reduce the reduction of the foaming ratio due to the bubble breaking during the bubble growth process while appropriately promoting the bubble breaking by the shear deformation at the die outlet. In addition, the depressurization speed at the die outlet may be set within an appropriate range so that the bubble nucleation density has an appropriate bubble size.
That is, by defining appropriate ranges of pressure gradient and pressure reduction rate at the die outlet (for pressure gradient (k), 50 MPa / m ≦ k ≦ 800 MPa / m, for pressure reduction rate (v), 5 MPa / s ≦ v ≦ 100 MPa / s), it is possible to obtain a polypropylene foam having an open cell structure and a sufficient expansion ratio and having excellent sound absorption characteristics by a simple means.

  On the other hand, when the pressure gradient (k) is less than 50 MPa / m, the occurrence of bubble breakage becomes remarkable in the die, and an extruded foam having a sufficient foaming ratio such as a foaming ratio of 10 times or more can be obtained. There are cases where it is not possible. On the other hand, when the pressure gradient (k) exceeds 800 MPa / m, it becomes difficult to form an open cell structure. The pressure gradient (k) is particularly preferably in the range of 100 MPa / m ≦ k ≦ 500 MPa / m.

  In addition, when the pressure reduction rate (v) is less than 5 MPa / s, the occurrence of bubble breakage in the inside of the die becomes remarkable, and it may not be possible to obtain an extruded foam having a sufficient foaming ratio such as a foaming ratio of 10 times or more. is there. On the other hand, when the pressure reduction rate (v) exceeds 100 MPa / s, it becomes difficult to form an open cell structure, and the sound absorption characteristics are further deteriorated. The pressure reduction rate distribution (v) is particularly preferably in the range of 20 MPa / s ≦ v ≦ 60 MPa / s.

The substance constants M (Pa · s ⁿ ) and n are values calculated as follows.
M (Pa · s ⁿ ) is a parameter indicating the degree of viscosity of the propylene resin, and the logarithm of both is plotted with respect to the relationship between the shear rate (γ) and the shear viscosity (η _M ), which is a specific value of the resin. The results are shown in FIG. As shown in FIG. 6, the shear viscosity (η) at a predetermined resin temperature depends on the shear rate (γ), and the shear rate is in the range of 10 ⁰ to 10 ² (s ⁻¹ ). It can be approximated by the following formula (IV-1). The material constant M indicates the slope in this formula (IV-1).

Then, based on the formula (IV-1), the value of the shear viscosity (η _M ) obtained when the shear rate (γ) is 10 ⁰ (s ⁻¹ ) may be adopted as M. The value of M used in the present invention is determined by the temperature and viscosity of the propylene-based resin, it is usually about 500~30000 (Pa · ^{s n).}

The material constant n is a parameter indicating the non-Newtonian property of the propylene-based resin, and the shear viscosity (η _M ) when the shear rate (γ) is 100 (s ⁻¹ ) is η _M (γ = 100). And can be calculated using the following formula (IV-2). In addition, the value of n applied to this manufacturing method is about 0.2-0.6 normally.

Thus, in the above-described formulas (I) and (II), M, which is a material constant of the propylene-based resin (a parameter indicating the degree of viscosity of the material, which varies depending on the viscosity and temperature of the material). Is about 500 to 30000, and n (similarly, a parameter indicating the non-Newtonian property of the material) is about 0.2 to 0.6, so that the pressure gradient (k) is 50 MPa / m ≦ k ≦ 800 MPa. / M, and the pressure reduction rate (v), the position where the cross-sectional area of the flow path perpendicular to the flow direction at the extrusion die outlet is minimized in order to satisfy 5 MPa / s ≦ v ≦ 100 MPa / s. volume flow Q (one inner tube die of the molding material 0.1 to 4.0 mm ² cross-sectional area a of the die hole, preferably passing through a 0.3 to 2.0 mm ^2, a single die outlet portion of Win) To 300 mm ³ / s, preferably may be such that the 10 to 150 mm ³ / s.

In this manufacturing method, it is considered that the resin flow path diameter in the vicinity of the extrusion die outlet is not constant (for example, the resin flow path diameter is small in the vicinity of the extrusion die outlet, that is, for extrusion. This takes into account the occurrence of a position where the cross-sectional area in the direction perpendicular to the flow direction is minimum in the resin flow path in the vicinity of the die outlet), and the diameter of the resin flow path is substantially constant in the vicinity of the extrusion die outlet. When the cross-sectional area is substantially constant, the constant cross-sectional area may be adopted as the cross-sectional area A in the formulas (I) and (II).
Specifically, it is desirable to adjust the decompression speed and pressure gradient according to the melt viscosity of the resin used for foam production and the shape of the die hole at the exit of the extruder. The area can be adjusted. That is, although it depends on the temperature and viscosity of the molten resin, increasing the size of the die hole can increase the area of the hole in the bubble breaking portion.
The area of the cell hole that affects the sound absorption performance, that is, the sound absorption performance, is remarkable when the area is larger than 2% of the total area of the cell (both areas are compared on the observation surface). It is known that the vibration of sound is reflected by the cell wall.

(2-2) Production of the first layer 2:
When manufacturing the 1st layer 2 in the extrusion foam 1 of this invention, operation according to the manufacturing procedure of the 2nd layer 3 mentioned above is performed. However, in the first layer 2, in order to reliably form a closed cell structure (the area of the hole (bubble breaking portion) formed in the cell wall is less than 2%) with a high expansion ratio, the above-mentioned is described. In the formula (I), the pressure gradient exceeds 800 MPa / m, and in the above-described formula (II), the pressure reduction rate (v) exceeds 100 MPa / s. By such setting, the area of the hole formed in the cell wall inside the foam is remarkably reduced, and an extruded foam in which the area of the hole in the bubble breaking part is less than 2% of the cell cross-sectional area can be produced.
As described above, although depending on the temperature and viscosity of the molten resin, when the size of the die hole is increased, the area of the hole of the bubble breaking portion can be increased.
In this embodiment, it can be set as 0.2-2 mm in diameter as a 1st extrusion hole which extrudes the strip 22 which should become the 1st layer 2 (The hole area of a bubble breaking part is small). On the other hand, the 2nd extrusion hole which extrudes the strip 32 which should become the 2nd layer 3 (the hole area of a bubble breaking part is large) is 1.1 times or more of the 1st extrusion hole mentioned above, A strip with many cell holes (bubble breakage) suitable for two layers can be formed.

(2-3) Lamination of first layer 2 and second layer 3:
When the extruded foam 1 is manufactured, the first layer 2 and the second layer 3 are laminated. In this lamination, for example, a plurality of strips are extruded and foamed from a tubular die assembly constituted by a plurality of tubular dies, or a plurality of strips are formed from an extrusion die in which a plurality of extrusion holes are formed. A technique of forming an extruded foamed strip converging body obtained by extrusion foaming and fusing the strips in the longitudinal direction and converging a large number thereof can be used.
As an example of the latter, for example, a number of strips 22 and 32 (see FIGS. 1 and 7) are formed from the extrusion dies 5 and 6 in which a plurality of extrusion holes 51 and 61 (see FIG. 7 described later) are formed. Extrusion foaming is performed, and the strips 22 and 32 are fused together in the longitudinal direction to form a bundle of extruded foam strips.
In this way, by forming an extruded foamed strip bundle having a large number of extruded foams of the strips 22 and 32, the foaming ratio of the extruded foam 1 can be increased, and the foaming ratio is high and sufficient. The extruded foam 1 having a thickness can be easily molded in various shapes.
The production of such an extruded foamed strip bundle is also known, for example, from Japanese Patent Laid-Open No. 53-1262.

FIG. 1 is a schematic view showing an embodiment of a configuration in the case where the extruded foam of the present invention is an extruded foam strip bundle. The extruded foam 1 (extruded foam strips 1) is a laminate composed of a first layer 2 and a second layer 3 (in FIG. 1 and FIG. 8 described later, a fibrous filler). 9 is not shown).
The first layer 2 is formed by converging a plurality of strips 22, and a plurality of foamed cells 21 are randomly present in the strips 22. The average diameter of the foam cell 21 can be, for example, about 5 to 400 μm.
The second layer 3 is also formed by converging a plurality of strips 32, and a plurality of foamed cells 31 are randomly present in the strips 32. The average diameter of the foam cell 31 can be, for example, about 5 to 5000 μm.
In addition, in the extrusion foam 1 shown in FIG. 1, the example which formed the skin layers 23 and 33 on the surface of the 1st layer 2 and the 2nd layer 3 is shown.

In order to obtain the extruded foam 1 having such a configuration of FIG. 1, as shown in FIG. 7, a plurality of strips 22 (extruded from the first extrusion die 5 in which a plurality of extrusion holes 51 are formed ( And a plurality of strips 32 (to become the second layer 3) extruded from the second extrusion die 6 in which a plurality of extrusion holes 61 are formed, and are stacked at a high temperature. After that, for example, it is possible to adopt a method of forming a laminated body by narrowing pressure while cooling with a pair of cooling sizing rollers 7.
In this way, by superposing the strips 22 and 32 in a high temperature state and then cooling to form a laminated body, the first layer 2 and the second layer 3 are used in the bonding step or the bonding step. No adhesive is required.
In FIG. 7, the cooling sizing roller 7 includes three cooling rollers 71, and the pair of cooling sizing rollers 7 are disposed so as to face each other with the extruded foam 1 interposed therebetween. Each of the cooling rollers 71 is provided with a water-cooling type temperature adjusting means (not shown) that can adjust the surface temperature.

In addition, although the shape of the strips 22 and 32 which comprise such an extrusion foaming strip bundling body 1 depends on the shape of the extrusion holes 51 and 61 formed in the extrusion dies 5 and 6, the extrusion hole 51 , 61 can be any shape such as a circle, a diamond, or a slit. In the molding, it is preferable that the pressure loss at the outlets of the extrusion dies 5 and 6 be 3 MPa to 50 MPa.
Moreover, the shape of the extrusion holes 51 and 61 formed in the extrusion dies 5 and 6 may be all the same shape, or various types of extrusion holes are formed in one extrusion die 51 and 61. You may do it.

Furthermore, for example, even when a circular extrusion hole is used, a plurality of types of circular extrusion holes having different diameters may be formed as the size of the diameter.
In addition, in the case of using a tubular die assembly configured by collecting a plurality of tubular dies in this way and manufacturing the second layer 3, each hole of the tubular die or the like is formed. It is preferable that the pressure gradient (k) and the pressure reduction rate (v) satisfy the requirements of the above formulas (I) and (II).

(2-4) Additional processing of extruded foam 1:
In the extruded foam 1 of the present invention, the second layer 3 may be provided with a portion where the strips 32 are not formed (non-striped portion 34).
FIG. 8 is a schematic view showing an aspect in which the non-striped portion 34 is formed in the second layer 3 in the propylene-based resin extruded foam 1 shown in FIG. Since the space formed by the non-striped portion 34 effectively absorbs sound waves in a specific frequency region, a more excellent sound absorbing performance can be exhibited.

  In order to form the non-striped portion 34 with respect to the second first layer 2, for an extrusion die in which a plurality of extrusion holes are formed (see, for example, the extrusion die 6 in FIG. 7), If a portion where the extrusion hole is not partially formed is provided, the strip is not extruded from the portion, and the non-striped portion 34 including the gap is preferably formed.

  In the extruded foam 1 of the present invention, at least a part of the surface of the second layer 3 may be communicated with the outside air. As described above, the second layer 3 communicates with the outside air, so that the space inside the foam efficiently absorbs the sound wave from the outside, so that the sound absorbing performance is improved.

Here, in order for the surface side of the second layer 3 to communicate with the outside air, a hole is formed in the surface portion of the second layer 3 (skin layer 33 in FIG. 1), or the skin layer 33 is shaved and opened. May be provided. When the skin layer 33 is not formed on the second layer 3, a hole or an opening may be provided in a portion that appears on the surface of the second layer 3. The diameter of the hole is preferably 0.1 to 3.0 mm.
In addition, since the frequency of the sound wave to be absorbed varies depending on the size of the hole (diameter, depth, volume, etc.), when the frequency of the noise to be absorbed is specified, it depends on the specified frequency. If the size of the hole (diameter, depth, volume, etc.) is appropriately determined, the sound absorption characteristics can be efficiently exhibited.

In order to form a hole on the surface side of the second layer 3 in this way, for example, as shown in FIG. 9, an infinite number of needle-like bodies 81 with respect to the cooling sizing roller 7 shown in FIG. When the second layer 3 is passed through the belt 8 on which the belt is disposed, the needle-shaped body 81 suitably forms a hole on the surface side of the second layer.
In addition, when an opening is formed by cutting the skin layer 33 of the second layer 3 or a portion appearing on the surface side, the opening is formed by a cutting blade when the extruded foam 1 is manufactured (in the extrusion foaming process). Alternatively, after the extruded foam 1 is manufactured, an opening may be formed by a cutting blade in the secondary processing.

  In producing at least one of the first layer 2 and the second layer 3, the extruded foam extruded from the extrusion die after the molding material is extruded from the extrusion die is substantially orthogonal to the extrusion direction. If the vacuum suction is performed along the direction in which the fiber filler 9 (not shown in FIGS. 1 and 8) is used, the fiber length direction of the fibrous filler 9, that is, the orientation direction of the fibrous filler 9 is determined by the propylene-based resin extruded foam. It can be set as the direction along the thickness direction, and the propylene-type resin extrusion foam 1 which has high energy absorption capability can be obtained.

(2-5) Specific apparatus for producing extruded foam 1:
FIG. 10 is a perspective view showing an extrusion die and a cooling sizing roller used for producing a propylene-based resin extruded foam. As shown in FIG. 10, the strips 22 and 32 extruded from the extrusion holes 51 and 61 of the extrusion dies 5 and 6 are in the thickness direction (the direction substantially perpendicular to the extrusion direction. The arrow Y shown in FIG. In the direction), and is then sandwiched between a pair of cooling sizing rollers 7 to be cooled.
The vacuum suction is performed by a vacuum suction device (not shown) disposed opposite to the strips 22 and 32.

In producing the extruded foam 1 of the present invention, as foaming means for foaming the first layer 2 and the second layer 3, physical foaming in which a fluid (gas) is injected into a molten resin material at the time of molding, or resin material Chemical foaming in which a foaming agent is mixed can be employed.
As physical foaming, the fluid to be injected includes an inert gas such as carbon dioxide (carbon dioxide gas), nitrogen gas, or the like. As chemical foaming, usable foaming agents include azodicarbonamide, azobisisobutyronitrile, and the like.

In the physical foaming described above, it is preferable to inject carbon dioxide gas or nitrogen gas in a supercritical state into the molten resin material.
Here, the supercritical state refers to a state in which the density of the gas and the liquid becomes equal and the two layers cannot be distinguished by exceeding the limit temperature and pressure at which the gas and the liquid can coexist, and occurs in this supercritical state. The fluid is called a supercritical fluid. Moreover, the temperature and pressure in a supercritical state are a supercritical temperature and a supercritical pressure. For example, in a carbon dioxide gas, it is 31 degreeC and 7.4 MPa, for example. The supercritical carbon dioxide gas or nitrogen gas may be injected into the resin material at about 4 to 15% by mass, and can be injected into the molten resin material in the cylinder.

  The shape of the extruded foam 1 is not particularly limited, and a known shape as a structural material, for example, a known shape such as a plate shape, a columnar shape, a rectangular shape, a convex shape, or a concave shape can be employed.

(2-6) Effect of the extruded foam 1 of this embodiment:
The propylene-based resin extruded foam 1 of the first embodiment described above has the following effects.
In other words, the first layer 2 constituting the extruded foam 1 has an independent cell property because the area of the foamed portion of the foamed cell is less than 2% of the cell cross-sectional area, and the foaming ratio is 10 times or more. The large number of air bubbles thus made difficult to conduct heat, resulting in an extruded foam having excellent heat insulation performance. It also has excellent mechanical strength such as impact strength and moisture resistance. Moreover, since the skin layer (skin layer) 23 exists in the surface layer of the first layer, the sound insulation performance is also excellent.
In addition, the second layer 3 is preferably formed with an open cell structure in which the area of the bubble-breaking portion of the foam cell is 2% or more of the average cell area, and a continuous air layer connected between the cells is formed. At the same time, since the expansion ratio is 10 times or more, the ratio of the air layer in the foam is increased, whereby an extruded foam having excellent sound absorbing performance is obtained.
Furthermore, since the propylene-based resin extruded foam 1 of the present invention contains the fibrous filler 9 so as to be more than 0% by mass and 60% by mass or less with respect to the entire molding material to be formed, The filler 9 is arranged not only so that the fiber length direction is along the extrusion direction of the propylene-based resin extruded foam 1 but also along the thickness direction due to the presence of the foamed foam cells 21 and 31. Thereby, even when a slight distortion occurs in the thickness direction of the propylene-based resin extruded foam 1, a high stress is generated, and the extruded foam has not only the sound absorption characteristics but also energy absorption capability.
And the propylene-type resin extrusion foam 1 of this invention provided with such a 1st layer 2 and the 2nd layer 3 becomes an extrusion foam excellent in energy absorption performance besides heat insulation performance and sound absorption performance, By setting the magnification to 10 times or more, the foam becomes light and the handleability is excellent.

  In addition, since the propylene resin, which is a constituent material, is excellent in recycling performance, and also has good chemical resistance and heat resistance, the propylene resin extruded foam 1 of the present invention also has various performances (recycling). Performance, chemical resistance, heat resistance). Furthermore, by using a propylene-based resin that is a low-cost material, an extruded foam having the above-described effects can be provided at a low cost.

Since the extruded foam 1 of the present invention is excellent in heat insulation performance and sound absorption performance in this way, structural materials in the automotive field (constituent members for interiors such as ceilings, floors, doors, etc.) and structural materials in the construction and civil engineering fields ( It can be applied to building materials).
In particular, in the case of structural materials for housing in the field of construction and civil engineering, sound absorbing performance is often required on the inside, and heat insulating performance is often required on the outside. If the first layer 2 in the extruded foam 1 is disposed on the inner side and the second layer 3 is disposed on the outer side, the effect can be maximized.

The propylene-based resin extruded foam 1 according to the first embodiment described above is improved in heat insulation performance and sound absorption performance by the first layer 2 and the second layer 3 based on the present invention, and energy generated by the fibrous filler 9. Absorption performance was secured. In addition to such a structure, damping performance can be added to the propylene resin extruded foam 1 by adding a specific olefin polymer.
[Second Embodiment]
In this embodiment, the basic structure of the propylene-based resin extruded foam 1 of the present invention is the same as that of the first embodiment described above. Here, the molding material constituting the propylene-based resin extruded foam 1 of the present embodiment includes an olefin having a loss tangent (tan δ) of 0.04 to 100 at a temperature of 298 K and a frequency of 10 Hz, in addition to the resin material described above. -Based polymers (specific olefin-based polymers) are included.

This specific olefin polymer has a loss tangent (tan δ) of 0.04 to 100 at a temperature of 298 K and a frequency of 10 Hz, and particularly preferably 0.04 to 10. If the loss tangent is 0.04 to 100, it exhibits viscous behavior, and when it is included in a propylene-based resin to form an extruded foam, excellent vibration damping performance can be exhibited. On the other hand, if the loss tangent is smaller than 0.04, sufficient vibration damping performance cannot be obtained, and if the loss tangent is larger than 100, it exhibits solid properties and does not absorb energy inside, and is a rigid propylene resin. Because it will vibrate together with this, it will also not be able to demonstrate vibration damping performance.
The loss tangent may be measured by, for example, a commercially available solid viscoelasticity measuring device (for example, DMS 6100: manufactured by Seiko Instruments Inc.).

  Moreover, such a specific olefin polymer (a) may be added so that the weight ratio (a / b) is 1/100 to 80/100 with respect to the polypropylene resin (b). It is preferable to add so that it may become 5 / 100-60 / 100. By including the olefin polymer so that the weight ratio is 1/100 to 80/100, the olefin polymer is appropriately dispersed on the wall surface of the foam cell in the foamed molded product made of polypropylene resin, and vibration damping is performed. Performance can be improved.

  As this specific olefin polymer, for example, a resin material disclosed in WO 03/070788 and WO 03/070790, a resin material disclosed in Japanese Patent No. 3255697, and the like can be used. Specific examples include a highly fluid 1-butene copolymer disclosed in WO 03/070788, or a similar 1-butene polymer.

As this 1-butene copolymer, specifically, those shown in the following first aspect or second aspect can be used. By using these, it is possible to reliably impart vibration damping performance to the extruded foam.
First, as the first aspect, the following requirements (1) to (3) are satisfied.
(1) Intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. is 0.01 to 0.5 dL / g
(2) Using a differential scanning calorimeter (DSC), hold the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then raise the temperature at 10 ° C./min. Crystalline resin (3) stereoregularity index {(mmmm) / (mmrr + rmmr)} defined as the peak top of the observed peak and having a melting point ( _Tm- D) of 0 to 100 ° C. is 30 or less

Moreover, this 1-butene polymer comprises the following (1 ′), (2) and (3 ′) as the second form.
(1 ′) Intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. is 0.25 to 0.5 dL / g
(2) Using a differential scanning calorimeter (DSC), hold the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then raise the temperature at 10 ° C./min. Mesopentad fraction (mmmm) determined from a crystalline resin (3 ′) ¹³ C-nuclear magnetic resonance (NMR) spectrum having a melting point (T _m -D) defined as the peak top of the observed peak of 0 to 100 ° C. Is less than 73%

  Among these, the 1-butene polymer of the first aspect has an intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. of 0.01 to 0.5 dL / g, and this intrinsic viscosity [η] is Preferably it is 0.1-0.5dL. If the intrinsic viscosity [η] is less than 0.01 dL / g, the physical properties (strength) may be reduced. On the other hand, if it exceeds 0.5 dL, the fluidity may be deteriorated.

The 1-butene polymer of the second aspect has an intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. of 0.25 to 0.5 dL / g, and this intrinsic viscosity [η] is preferably Is 0.3 to 0.5 dL / g.
When the intrinsic viscosity [η] is smaller than 0.25 dL / g, the molecules that connect the crystals are insufficient, and the toughness (tensile elongation at break) decreases. When the intrinsic viscosity [0.5] exceeds 0.5 dL / g, the viscosity increases excessively. In some cases, fluidity is lowered and molding defects occur.

The 1-butene polymer according to the first and second aspects described above is a crystalline resin having a melting point ( _Tm- D) of 0 to 100 ° C. with a differential scanning calorimeter (DSC) from the viewpoint of softness. Is required, and preferably 0 to 80 ° C.

In addition, melting | fusing point ( _Tm- D) is calculated | required by DSC (abbreviation of Differential Scanning Calorimetry). That is, using a differential scanning calorimeter (DSC-7: manufactured by Perkin Elmer), a 10 mg sample was held at −10 ° C. for 5 minutes under a nitrogen atmosphere, and then the melting point obtained by raising the temperature at 10 ° C./min. The peak top of the peak observed on the highest temperature side of the endothermic curve is the melting point (T _m -D) of the measurement target. Here, “crystalline resin” in this specification refers to a resin in which T _m -D is observed.

  In the 1-butene polymer of the first embodiment, the stereoregularity index {(mmmm) / (mmrr + rmmr)} is 30 or less, preferably 20 or less, more preferably 15 or less. If this stereoregularity index exceeds 30, the flexibility of the viscous material may be reduced, and the vibration absorption effect may be reduced.

  Here, the mesopentad fraction (mmmm) is preferably 90% or less, more preferably 85% or less, and particularly preferably 80% or less. When the mesopentad fraction (mmmm) exceeds 90%, the flexibility and the secondary workability may be reduced.

  The 1-butene polymer of the second embodiment has a mesopentad fraction (mmmm) of 73% or less. If the mesopentad fraction (mmmm) exceeds 73%, the physical cross-linking points become excessive, and the flexibility may decrease.

In such a 1-butene polymer, the mesopentad fraction (mmmm) was measured by “Polymer Journal, 16, 717 (1984)”, J. A. et al. “Macromol. Chem. Phys., C29, 201 (1989)” reported by Randall et al. It was determined according to the method proposed in “Marcomol. Chem. Phys., 198, 1257 (1997)” reported by Busico et al. That is, the signals of methylene group and methine group were measured using ¹³ C-nuclear magnetic resonance spectrum, and the mesopentad fraction in the poly (1-butene) molecule was determined.

The ¹³ C-nuclear magnetic resonance spectrum may be measured using the following apparatus and conditions.
Apparatus: JNM-EX400 type 13C-NMR apparatus manufactured by JEOL Ltd. Method: Complete proton decoupling method Concentration: 230 mg / ml Solvent: 90:10 (volume ratio) mixing of 1,2,4-trichlorobenzene and heavy benzene Solvent temperature: 130 ° C
Pulse width: 45 °
Pulse repetition time: 4 seconds Operation: 10,000 times

  In such a 1-butene polymer, the stereoregularity index {(mmmm) / (mmrr + rmmr)} is calculated from the values obtained by measuring (mmmm), (mmrr) and (rmmr) by the above-described method. do it.

In addition to the above requirements, the 1-butene polymer of the first and second embodiments preferably has a weight average molecular weight (M _w ) measured by the GPC method of 10,000 to 100,000. . If _Mw is less than 10,000, the physical properties (strength) may decrease. On the other hand, if _Mw exceeds 100,000, the fluidity is lowered and the workability may be poor.
In addition, above-mentioned _Mw / _Mn is the value computed from the mass mean molecular weight ( _Mw ) and number average molecular weight ( _Mn ) of polystyrene conversion measured with the following apparatus and conditions by GPC method.

(GPC measuring device)
Column: TOSO GMHHR-H (S) HT
Detector: RI detector for liquid chromatogram WATERS 150C

(Measurement condition)
Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 1.0 ml / min Sample concentration: 2.2 mg / ml Injection volume: 160 microliter Calibration curve: Universal Calibration
Analysis program: HT-GPC (Ver.1.0)

  The 1-butene polymer of the first aspect preferably has a tensile modulus measured by a tensile test according to JIS K7113 of 500 MPa or less, and more preferably 300 MPa or less. If the tensile modulus exceeds 500 MPa, sufficient softness may not be obtained.

  When the 1-butene polymer is a copolymer, it is preferably a random copolymer. The structural unit obtained from 1-butene is preferably 50 mol% or more, more preferably 70 mol% or more. When the structural unit derived from 1-butene is smaller than 50 mol%, the secondary workability may be deteriorated.

  When the 1-butene polymer is a copolymer, the randomness index R obtained by the following formula (U) from the α-olefin chain is preferably 1 or less.

Here, R is an index representing randomness, and the smaller the R, the higher the isolation of the α-olefin (comonomer) and the more uniform the composition. This R is preferably 0.5 or less, and more preferably 0.2 or less.
When R is 0, there is no αα chain, and the α-olefin chain is completely isolated.

The butene content and R when the 1-butene polymer is a propylene / butene copolymer may be measured as follows.
Specifically, the butene content and R can be calculated by the following method by measuring a ¹³ C-NMR spectrum under the following measurement conditions using a JNM-EX400 type NMR apparatus manufactured by JEOL Ltd. Good.

(Measurement condition)
Sample concentration: 220 mg / NMR solution 3 ml NMR solution: 1,2,4-trichlorobenzene / benzene-d6 (90/10 vol%)
Measurement temperature: 130 ° C
Pulse width: 45 °
Pulse repetition time: 10 seconds Integration count: 4000 times

Under the above measurement conditions, PP, PB, and BB chains are C. According to the method proposed in Randall, Macromolecules, 1978, 11, 592, the signal of Sαα carbon in the ¹³ C-nuclear magnetic resonance spectrum was measured, and the PP, PB, BB dyad chain fraction in the copolymer molecular chain was measured. Asked.
The butene content and the randomness index R were determined from the following formula (W) and formula (X) from each obtained dyad chain fraction (mol%).

The butene content and R when the 1-butene polymer is an octyne / butene copolymer may be measured as follows. Specifically, the butene content and R can be calculated by the following method by measuring a ¹³ C-NMR spectrum under the following measurement conditions using a JNM-EX400 type NMR apparatus manufactured by JEOL Ltd. Good.

(Measurement condition)
Sample concentration: 220 mg / NMR solution 3 ml NMR solution: 1,2,4-trichlorobenzene / benzene-d6 (90/10 vol%)
Measurement temperature: 130 ° C
Pulse width: 45 °
Pulse repetition time: 10 seconds Integration count: 4000 times

Under the above measurement conditions, a signal of Sαα carbon in the ¹³ C-nuclear magnetic resonance spectrum was measured, and a BB chain observed at 40.8 to 40.0 ppm, an OB chain observed at 41.3 to 40.8 ppm, 42 The OO, OB, and BB dyad chain fractions in the copolymer molecular chain were determined from the peak intensity derived from the OO chain observed at .5 to 41.3 ppm.
The butene content and randomness index R were determined from the following formula (Y) and formula (Z) from the obtained dyad chain fractions (mol%).

  The 1-butene copolymer can be easily obtained by the method for producing a 1-butene copolymer disclosed in WO 03/070788.

  The propylene-based resin extruded foam 1 of the present invention having such a configuration is an olefin whose loss tangent (tan δ) at a temperature of 298 K and a frequency of 10 Hz is 0.04 to 100 with respect to the propylene-based resin with respect to the molding material to be formed. Since the olefin polymer, which is a viscous substance, is present in a uniformly dispersed state on the wall surface of the foam cell that constitutes the foamed molded product. In addition to the above-described heat insulation performance, sound absorption performance and energy absorption performance, an extruded foam imparted with vibration damping performance can be provided.

  The aspect described above shows one embodiment of the present invention, and the present invention is not limited to the above-described embodiment, and has the configuration of the present invention to achieve the object and effect. Needless to say, modifications and improvements within the scope of the present invention are included in the content of the present invention. Further, the specific structure, shape, and the like in carrying out the present invention are not problematic as other structures, shapes, and the like as long as the objects and effects of the present invention can be achieved.

In the above-described embodiment, the propylene-based resin extruded foam 1 has an example of a laminated structure in which the layered first layer 2 and the layered second layer 3 are laminated one by one. For example, the first layer 2 and the second layer 3 may be a multilayer of two or more layers. Moreover, you may employ | adopt the structure that many 1st layers 2 and 2nd layers 3 are arranged at random with respect to the extrusion foam. That is, as long as one extruded foam 1 is formed by the first layer 2 and the second layer 3, the configuration thereof is arbitrary.
Further, in order to obtain the extruded foam 1 having the configuration shown in FIG. 1, a plurality of extrusion dies as shown in FIG. 7 are not necessarily required. For example, as shown in FIG. 11, there may be one extrusion die. Here, the extrusion die 90 includes a plurality of extrusion holes 910 and a plurality of extrusion holes 920 as two types of extrusion holes.
In addition, the specific structure, shape, and the like in the implementation of the present invention may be other structures as long as the object of the present invention can be achieved.

EXAMPLES Hereinafter, although an Example and a manufacture example are given and this invention is demonstrated more concretely, this invention is not limited to the content of an Example etc. at all.
The physical properties in the following production examples and examples were measured by the following methods.

(1) Mass fraction of the first stage propylene polymer component (component 1) and the second stage propylene polymer component (component 2):
It calculated | required from the mass balance using the flowmeter integrated value of the propylene supplied continuously at the time of superposition | polymerization.

(2) Intrinsic viscosity [η]:
Measurements were made in a 135 ° C. tetralin solvent. The intrinsic viscosity [η ₂ ] of component 2 was calculated by the following formula (V).

［η_total］ ：プロピレン重合体全体の極限粘度（ｄL／ｇ）
［η_１］ ：成分１の極限粘度（ｄＬ／ｇ）
Ｗ_１ ：成分１の質量分率（質量％）
Ｗ_２ ：成分２の質量分率（質量％）

[Η _total ]: The intrinsic viscosity of the entire propylene polymer (dL / g)
[Η ₁ ]: Intrinsic viscosity of component 1 (dL / g)
W ₁ : Mass fraction of component 1 (mass%)
W ₂ : Mass fraction of component 2 (mass%)

(3) Melt flow rate (MFR):
In accordance with JIS K7210, the temperature was 230 ° C. and the load was 2.16 kgf.

(4) Melt tension:
Capillograph 1C (manufactured by Toyo Seiki Co., Ltd.) was used, and measurement was performed at a measurement temperature of 230 ° C. and a take-up temperature of 3.1 m / min. In the measurement, an orifice having a length of 8 mm and a diameter of 2.095 mm was used.

(5) Viscoelasticity measurement:
The measurement was performed with an apparatus having the following specifications. The storage elastic modulus G ′ can be obtained from the real part of the complex elastic modulus.
Apparatus: RMS-800 (Rheometrics)
Temperature: 190 ° C
Distortion: 30%
Frequency: 100 rad / s to 0.01 rad / s

[Production Example 1]
Propylene-based multistage polymer production:
(I) Preparation of prepolymerization catalyst component:
After thoroughly drying the 5-liter flask equipped with a stirrer with an internal volume of 5 liters and replacing with nitrogen gas, 4 liters of dehydrated heptane and 140 grams of diethylaluminum chloride were added, and a commercially available Solvay type titanium trichloride catalyst ( 20 g of Tosoh Finechem Co., Ltd. was added. While maintaining this at 20 ° C. with stirring, propylene was continuously introduced. After 80 minutes, stirring was stopped to obtain a pre-catalyst component in which 0.8 g of propylene was polymerized per 1 g of titanium trichloride catalyst.

(Ii) Polymerization of propylene (first stage):
A stainless steel autoclave with a stirrer with an internal volume of 10 liters was sufficiently dried and replaced with nitrogen gas, 6 liters of dehydrated heptane was added, and nitrogen in the system was replaced with propylene. Thereafter, propylene was introduced with stirring to stabilize the inside of the system at an internal temperature of 60 ° C. and a total pressure of 0.78 MPa, and then the prepolymerized catalyst component obtained in (i) was converted to 0.75 g in terms of solid catalyst. The polymerization was started by adding 50 ml of the contained heptane slurry. When the propylene was continuously supplied for 35 minutes, the polymer production amount obtained from the integrated value of the propylene flow rate was 151 g. As a result of sampling and analyzing a part thereof, the intrinsic viscosity was 14.1 dL / g. Thereafter, the internal temperature was lowered to 40 ° C. or lower, the stirring was loosened, and the pressure was released.

(Iii) Polymerization of propylene (second stage):
After depressurization, the internal temperature was again adjusted to 60 ° C., 0.15 MPa of hydrogen was added, and propylene was introduced while stirring. While continuously supplying propylene at a total pressure of 0.78 MPa, polymerization was performed at 60 ° C. for 2.8 hours. At this time, as a result of sampling and analyzing a part of the polymer, the intrinsic viscosity was 1.16 dL / g.

  After completion of the polymerization, 50 ml of methanol was added, and the temperature was lowered and the pressure was released. The entire contents were transferred to a filtration tank equipped with a filter, 100 ml of 1-butanol was added, and the mixture was stirred at 85 ° C. for 1 hour, followed by solid-liquid separation. Further, the solid part was washed twice with 6 liters of heptane at 85 ° C. and vacuum-dried to obtain 3.1 kg of a propylene polymer.

  From the above results, the polymerization weight ratio in the first stage and the second stage was 12.2 / 87.8, and the intrinsic viscosity of the propylene polymerization component produced in the second stage was determined to be 1.08 dL / g.

Then, with respect to 100 parts by weight of the resulting propylene-based multistage polymer powder, 600 ppm of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as an antioxidant and 500 ppm of calcium stearate as a neutralizing agent were added. The mixture was melted and kneaded at a temperature of 230 ° C. with a lab plast mill single screw extruder (manufactured by Toyo Seiki Co., Ltd., φ20 mm) to prepare propylene polymer pellets.
Table 1 shows the physical properties and resin properties of the resulting propylene-based multistage polymer.

(Physical properties and resin properties of propylene-based multistage polymers)

[Example 1]
Production of propylene-based resin extruded foam (extruded foam strips):
A molding material obtained by mixing the pellet-shaped propylene-based multistage polymer obtained in Production Example 1 with a fibrous filler having the following specifications was used. In addition, content of this fibrous filler was 10 mass% with respect to the whole molding material.

(Fibrous filler)
Material Glass fiber (MA486A (trade name) manufactured by Asahi Fiber Glass Co., Ltd.)
Average fiber length 3mm
Average fiber diameter 13μm

This molding material was produced by using a tandem extrusion foam molding apparatus disclosed in Japanese Patent Application Laid-Open No. 2004-237729 (an MCF extrusion molding machine manufactured by Kawata, a single screw extruder with a screw diameter of φ50 mm, and a single screw extruder with a screw diameter of φ35). A large number of circular extrusion holes (circular pipe dies, all having the same cross-sectional area) were assembled as dies for each of the two apparatuses. A propylene-based resin extruded foam in which a first layer and a second layer, which are plate-shaped extruded foam strips in which a large number of extruded foam strips are bundled, are laminated by the following method. Manufactured.
The foaming was performed by injecting a CO ₂ supercritical fluid with a φ50 mm single screw extruder.

Specifically, with a φ50 mm single screw extruder, while injecting a CO ₂ supercritical fluid while melting the molding material, the fluid is sufficiently dissolved in the molten molding material to be uniform, Extruded from the connected φ35 mm single screw extruder so that the resin temperature at the die outlet in the φ35 mm single screw extruder is 180 ° C. (185 ° C. in the second extrusion foaming), and the fine extruded from the two devices. An extruded foam was formed by laminating strips (first layer and second layer). Details of the production conditions are shown below.
In addition, what is necessary is just to employ | adopt the value measured with the thermocouple thermometer, for example as the resin temperature in the die | dye exit of (phi) 35 mm single-screw extruder, and this resin temperature can be considered to be the temperature of the molten resin extruded while foaming. it can.
In the production of the second layer, under this condition, the pressure gradient calculated by the formula (I) was 450 MPa / m, and the pressure reduction rate calculated by the formula (II) was 60 MPa / s.

(Production conditions: first layer)
CO ₂ supercritical fluid: 7% by mass
Extrusion amount: 8kg / hr
Diameter of one die exit: 0.5mm
Die upstream part resin pressure: 8MPa
Extrusion temperature at the die outlet: 185 ° C

(Production conditions: Second layer)
Material constant M (Pa · s ⁿ ): 6000 (value at 185 ° C.)
Material constant n: 0.4
CO ₂ supercritical fluid: 7% by mass
Extrusion amount: 8kg / hr
Die outlet upstream resin pressure: 8MPa
Flow rate per circular tube die at the die outlet: 100 mm ³ / s
Diameter of one die exit: 0.8mm
Cross-sectional area of flow path: 0.5 mm ²
Extrusion temperature at the die outlet: 185 ° C

  And the expansion ratio, average diameter, and closed cell ratio of the first layer and the second layer in the propylene-based resin extruded foam of Example 1 obtained in this manner were measured according to the following conditions. The results are shown in Table 2.

(Measurement condition)
Foaming ratio: The density was calculated by dividing the weight of the obtained extruded foam by the volume obtained using the water casting method.
Average diameter: Measured according to ASTM D3576-3577.
Cross-sectional area of foam breaking part: The foam was cut, a cross-sectional photograph was taken, the area of the corresponding region on the photograph was measured, and the ratio to the total area of all cell cross-sections measured in the same manner was calculated.

(Measurement result)

  Moreover, the energy absorption capability of the propylene-based resin extruded foam obtained in Example 1 and the orientation direction of the fibrous filler were measured under the following conditions.

(Measurement of energy absorption capacity)
Using a compression tester (TENSILON / CTM-I-5000 (trade name) manufactured by Baldwin Co., Ltd.), a compression test was performed at 300 K under a compression strain rate of 1.0 × 10 ⁻² / S.

(Measurement of orientation direction of fibrous filler)
The propylene-based resin extruded foam was cut in a direction perpendicular to the thickness direction, and the orientation angle was evaluated from the major axis and the minor axis of the elliptical fiber cut surface in the cross section of the propylene-based resin extruded foam. When this waste direction angle is 45 ° or less, it is regarded as being oriented in the thickness direction of the propylene resin extruded foam, and in the thickness direction with respect to the total number of fibers in the cross section of the propylene resin extruded foam. The ratio of the number of oriented fibers was evaluated.

In the propylene-based resin extruded foam obtained in Example 1, 25% of the total number of fibrous fillers is arranged along the thickness direction of the propylene-based resin extruded foam in both the first layer and the second layer. I was able to confirm.
Furthermore, as a result of measuring the energy absorption ability, it was a very high result, and the propylene-based resin extruded foam obtained in Example 1 produced a large stress even with a small strain and confirmed that the energy absorption ability was excellent. It was done.

And about the propylene-type resin extrusion foam of Example 1, when the heat insulation performance and the sound absorption performance were evaluated using the conventional method, the favorable result was able to be obtained.
From the above, it was confirmed that the propylene-based resin extruded foam of the present invention had excellent heat insulation performance, sound absorption performance, and energy absorption performance.

[Example 2]
The 1-butene copolymer disclosed in Example 1 of WO03 / 070788 was added to the molding material of Example 1 containing the propylene-based multistage polymer (b). The 1-butene copolymer (a) disclosed in Example 1 of WO 03/070788 has a weight ratio (a / b) of 15/85 (propylene-based multistage polymer: 85% by mass, 1-butene system) 15% by mass of the copolymer was mixed to obtain a molding material. Table 3 shows the 1-butene copolymer physical properties and resin properties.
For the measurement items in Table 3, the loss tangent (tan δ) at a temperature of 298 K and a frequency of 10 Hz was measured with a solid viscoelasticity measuring device (DMS 6100: manufactured by Seiko Instruments Inc.), and other items were The measurement was performed according to the method described in WO 03/70788. Other conditions are the same as those in the first embodiment.

(Physical properties and resin properties of 1-butene copolymer)

  The expansion ratio, average cell diameter, and bubble breakage cross-sectional area of the first and second layers of the propylene-based resin extruded foam thus obtained were measured according to the same conditions as in Example 1. The results are shown in Table 4.

(result)

    When the orientation of the fibrous filler and the energy absorption capacity were measured in the same manner as in the evaluation of Example 1 described above, both the first layer and the second layer accounted for 24% of the total number of fibrous fillers. It can be confirmed that they are arranged along the thickness direction of the extruded foam. This propylene-based resin extruded foam had a very high energy absorption capability.

And about the propylene-type resin extrusion foam of Example 2, when the heat insulation performance sound absorption performance and the vibration suppression performance were evaluated using the conventional method, the favorable result was able to be obtained.
From the above, it was confirmed that the propylene-based resin extruded foam of the present invention has excellent heat insulation performance, sound absorption performance, vibration damping performance, and energy absorption performance.

  Since the propylene-based resin extruded foam of the present invention is excellent in energy absorption performance in addition to heat insulation performance and sound absorption performance, for example, structural materials that require sound absorption performance in the field of construction, civil engineering, and automobiles (for example, building materials, It can be advantageously used for interior components such as automobile ceilings, floors, and doors.

It is the schematic diagram which showed 1st embodiment of the propylene-type resin extrusion foam of this invention. It is a schematic diagram which shows the structure of the 1st layer of the said embodiment. It is a schematic diagram which shows the structure of the 2nd layer of the said embodiment. It is a figure which shows the stress-strain curve of the propylene-type resin extrusion foam which does not contain the fibrous filler of the said embodiment. It is a figure which shows the stress-strain curve of the propylene-type resin extrusion foam of the said embodiment. It is a figure which shows the relationship between the shear rate ((gamma)) and the shear viscosity ((eta)) of the said embodiment. It is a schematic diagram which shows the one aspect | mode of the die for extrusion used for manufacture of the propylene-type resin extrusion foam of the said embodiment, and the sizing roller for cooling. It is the schematic diagram which showed the other aspect of the propylene-type resin extrusion foam of this invention. It is a schematic diagram which shows the other aspect of the extrusion die used for manufacture of a propylene-type resin extrusion foam, and the sizing roller for cooling. It is a perspective view which shows the other aspect of the extrusion die used for manufacture of a propylene-type resin extrusion foam, and a cooling sizing roller. It is a schematic diagram which shows the other aspect of the extrusion die used for manufacture of a propylene-type resin extrusion foam, and the sizing roller for cooling.

Explanation of symbols

1 ... Propylene-based resin extruded foam (extruded foam strips)
2 ... 1st layer 3 ... 2nd layer 21, 31 ... Foam cell 22, 32 ... Strip 23, 33 ... Skin layer 34 ... Unstriped section 5, 6 ... Extrusion die 51, 61 ... Extrusion hole 7 ... Cooling Sizing roller 71 ... Cooling roller 8 ... Belt 81 ... Needle-like body 9 ... Fibrous filler

Claims (15)

A propylene-based resin extruded foam produced by melt-kneading a composition comprising a polypropylene-based resin and a foaming agent in an extruder and discharging the composition to a low-pressure region, wherein the following first layer and second layer are provided in the thickness direction: A propylene-based resin extruded foam characterized by having a multilayer structure including at least two layers.
(First layer) With the cross-section of the foam as the observation surface, the total area of the cell wall holes (bubble breakage) appearing on this observation surface is less than 2% of the total area of all cell cross-sections appearing on the observation surface Yes, a layer made of a polypropylene resin foam having an expansion ratio of 10 times or more.
(Second layer) With the cross section of the foam as the observation surface, the total area of the cell wall holes (bubble breakage) appearing on this observation surface is 2% or more of the total area of all cell cross sections appearing on the observation surface Yes, a layer made of a polypropylene resin foam having an expansion ratio of 10 times or more. 2. The propylene-based resin extruded foam according to claim 1, wherein the cell has an area of 1 × 10 ⁻⁵ mm ² or more in the cell wall hole (foam portion) on the observation surface of the foam of the second layer. A propylene-based resin extruded foam, characterized in that the total area of wall holes (bubble breakage) is 2% or more of the total area of the cross-sections of all cells appearing on the observation surface. 3. The propylene-based resin extruded foam according to claim 1 or 2, wherein the foam cell of the second layer communicates with outside air. The propylene-based resin extruded foam according to any one of claims 1 to 3, wherein an average diameter of the foam cells of the first layer is 500 µm or less. 5. The propylene-based resin extruded foam according to claim 4, wherein the foam cell of the second layer has an average diameter of 100 μm or more and 5 mm or less. 6. The extruded foam produced in the propylene-based resin extruded foam according to any one of claims 1 to 5, wherein a plurality of strips are ejected simultaneously from one or more dies and then a large number of these strips are converged. A propylene-based resin extruded foam, which is a foamed strip-like bundle. The propylene-based resin extruded foam according to claim 6, wherein the propylene-based resin extruded foam has a portion where the strip is not formed in part. The propylene resin extruded foam according to any one of claims 1 to 7, wherein the propylene resin constituting the first layer and the second layer is composed of the following components (A) and (B), respectively. A propylene-based resin extruded foam, characterized by being a multi-stage polymer.
(A) Propylene homopolymer component having intrinsic viscosity [η] measured in a tetralin solvent at 135 ° C. of more than 10 dL / g, or copolymer component of propylene and α-olefin having 2 to 8 carbon atoms, total weight 5-15 mass% is contained in the coalescence.
(B) A propylene homopolymer component having a [η] of 0.5 to 3.0 dL / g measured in a tetralin solvent at 135 ° C. or a copolymer component of propylene and an α-olefin having 2 to 8 carbon atoms. Is contained in the total polymer in an amount of 85 to 95% by mass. 5. The propylene-based resin extruded foam according to claim 4, wherein the propylene-based multistage polymer has a relationship between a melt flow rate (MFR) at 230 ° C. and a melt tension (MT) at 230 ° C. of the following formula (III): Propylene-based resin extruded foam characterized by comprising.

The propylene-based resin extruded foam according to any one of claims 1 to 9, wherein at least one layer or all layers contain a fibrous filler, and the content of the fibrous filler is 60% by mass or less. A propylene-based resin extruded foam characterized by being. The propylene resin extruded foam according to any one of claims 1 to 9, wherein the olefin polymer is contained in at least one layer or all layers, and the olefin polymer is at a temperature of 298K and a frequency of 10Hz. A propylene-based resin extruded foam characterized by having a loss tangent (tan δ) of 0.04 to 100. Propylene-based resin extruded foam manufacturing method for producing a propylene-based resin extruded foam having a multilayer structure of at least two layers by melting and kneading a composition comprising a polypropylene-based resin and a foaming agent in an extruder and discharging the composition to a low pressure region Because
A die in which a first extrusion hole having a diameter of 0.2 to 2 mm and a second extrusion hole having a diameter 1.1 times or more that of the first extrusion hole are arranged in layers on the die of the extruder. Use
A method for producing a propylene-based resin extruded foam, characterized in that foams extruded from the extrusion holes of the die are converged in layers to form a multi-layered plate. In the method for producing a propylene-based resin extruded foam according to claim 12,
Using a plurality of dies including a die formed with the first extrusion hole and a die formed with the second extrusion hole, the foam extruded from the extrusion hole of each die is converged in layers. A method for producing a propylene-based resin extruded foam. In the manufacturing method of the propylene-type resin extrusion foam of Claim 12 or Claim 13,
A propylene-based resin extruded foam characterized by forming a plate-like extruded foam having a multi-layer structure and then opening a hole in the skin portion with one or more needle-like bodies to allow some foamed cells to communicate with the outside air. Production method. In the manufacturing method of the propylene-type resin extrusion foam in any one of Claims 12-14,
A method for producing a propylene-based resin extruded foam, comprising forming a multi-layer plate-like extruded foam and then cutting a skin portion thereof to allow some foamed cells to communicate with the outside air.

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