KR20080042046A - Constructional heat-insulating foam board and process for production thereof - Google Patents

Abstract

The invention provides a constructional heat-insulating foam board of a polyolefin resin composition which exhibits excellent extrusion foamability and excellent heat insulation performance and which is recyclable and can be produced at a low cost continuously and stably. A constructional heat-insulating foam board, characterized by being produced by expanding a polyolefin resin composition containing a linear polypropylene resin exhibiting a melt tension of 5 to 30g at 230°C with a blowing agent containing supercritical carbon dioxide as the essential component at an expansion ratio of 10 or above.

Description

Foam board for insulation building materials and its manufacturing method {CONSTRUCTIONAL HEAT-INSULATING FOAM BOARD AND PROCESS FOR PRODUCTION THEREOF}

The present invention relates to a foam board for thermal insulation building materials of a polyolefin resin composition and a method for producing the same.

The foam of the polyolefin resin composition is characterized by a balance between its excellent performance and cost, and furthermore, the recycling property of a resin which has recently received a good reputation, and is widely used mainly for thermal insulation building materials, automobile parts, packaging buffers, and the like. .

For example, as a thermal insulation building material use, a foam board made of polypropylene resin or polyethylene resin is constructed inside a floor or a wall of a building, and exhibits excellent thermal insulation performance and is widely used in the market.

The foam of these polyolefin resin compositions is widely used in the world as such a very useful material, and the manufacturing method is also researched and implemented a lot. Currently, the method for producing a polyolefin-based resin composition foam is largely classified into two types.

The first production method is called a beading method, and after impregnating a polyolefin resin composition pellet dispersed in water or the like in a pressurized airtight container under high temperature and high pressure, it is rapidly discharged under atmospheric pressure and so-called prefoaming. It is a method of manufacturing an in-mold molded object by manufacturing a particle | grain, filling the prefoamed particle | grain in a mold, and heat-cooling.

Also with this bead method, a foamed board made of a polyolefin resin composition can be produced, but a foam produced by a conventional bead method has a large average cell diameter of about 200 to 500 µm, so that thermally sufficient materials can be obtained as thermal insulation building materials. Can't. In addition, the bead method is a batch production method, which needs to be formed in a steam mold after the pellet production process and the pre-expanded particle production process. There is a drawback to increase.

The second production method is called so-called extrusion method, and the polyolefin resin composition particles are introduced into the extruder, and melt-kneaded under heating and pressure using a hydrocarbon, a chemical blowing agent, or the like as a blowing agent, if necessary, and then A method of obtaining a foam through a die designed into a shape.

About this extrusion method, for example, in patent document 1, after adding a polyfunctional monomer and a thermal decomposition type foaming agent to polypropylene resin, melt-mixing previously, irradiating an electron beam, and crosslinking a polypropylene resin further, Disclosed are a method of decomposing and foaming a pyrolytic foaming agent by heating.

In addition, in the extrusion method described in Patent Document 2, by forming a polypropylene resin composition having the properties of the following (1) to (4), with polypropylene as a main component, a large variety of molded articles excellent in appearance and rigidity can be obtained. It is said to be possible. That is, (1) high molecular weight of the intrinsic viscosity [η] 8-13 dl / g measured in melt flow rate (MFR) of 0.01-5 g / 10min measured under 230 degreeC and 2.16 kg load, and in 135 degreeC decalin The content of polypropylene is 15 to 50% by weight, (3) the number of gels is 3000/450 cm 2 or less, and (4) the molecular weight distribution Mw / Mn measured by gel permeation chromatography (GPC) is 6 to 20. And Mz / Mw of 3.5 or more, a polypropylene resin composition which can be efficiently obtained by high-speed molding large-sized molded articles having high melt tension, excellent moldability, good rigidity, and good appearance and are not easily deformed. Is disclosed.

Further, Patent Document 3 discloses a thermoplastic polymer (A), 10 to 50 wt% of ultrahigh molecular weight polyolefin (b-1) having an intrinsic viscosity [η] of 10 to 40 dl / g, and a [η] of 0.1 to 5 dl / g. Polyolefin composition (B) containing 90-50 weight% of polyolefin (b-2) [total the sum of (b-1) and (b-2) to 100 weight%]], (A) and (B By foaming a thermoplastic polymer composition having a weight ratio [(A) / (B)] of 95/5 to 60/40, the size of the bubbles is fine and uniform at two times or more high foaming ratio, and the thermoplastic stability is excellent in extrusion stability. Foamed molded articles of the polymer are disclosed.

In Patent Document 4, a resin composition composed of a fluoroalkane ester of a thermoplastic resin and an aliphatic carboxylic acid is melted in an extruder, and an inert gas in a supercritical state, which is a blowing agent, is added to provide a thermoplastic resin composition and an inert gas. In a gas dissolving step of forming a completely compatible state, a cooling step of lowering the temperature of the molten resin while maintaining a pressure equal to or higher than the critical pressure of an inert gas that is a blowing agent, and a die heated to the glass transition temperature of the resin, The nucleation process of generating cell nuclei by releasing pressure to atmospheric pressure finally from the pressure above the critical pressure of the inert gas, and cooling the foam below the glass transition temperature or crystallization temperature of the thermoplastic resin to control the cell diameter Thermoplastic resin foam comprising a foam control process It discloses a process for producing the same.

[Patent Document 1] Japanese Patent Application Laid-Open No. 07-173317

[Patent Document 2] WO99 / 07752

[Patent Document 3] Japanese Unexamined Patent Publication No. 2004-217755

[Patent Document 4] Japanese Patent Application Laid-Open No. 10-175248

Disclosure of the Invention

Problems to be Solved by the Invention

However, in the invention described in Patent Literature 1, there is a problem that the molding step, the crosslinking step, and the foaming step are not suitable for continuous mass production because there are many steps. In recent years, there has been a tendency to require recycling and use of plastic molded articles due to environmental problems, and the like, which provides thermal history such as melt repelletization in the process of recycling and regenerating the polyolefin resin composition used in such a method. By passing through the step, the decomposition of the crosslinked body, the graft body, and the like occur relatively easily, so that the melting characteristics required for foaming cannot be maintained and the recycling property is insufficient.

In addition, in the inventions disclosed in Patent Documents 2 and 3, since a foam having a relatively low foaming magnification of about five times is easily obtained, the bubbles (cells) of the foam are uniformly dispersed foams, but still sufficient thermal insulation performance is obtained. I didn't lose. For this reason, in order to obtain more excellent heat insulation performance, it is thought that foaming magnification is 10 times or more, but when it is 10 times or more high foaming magnification, foam which has a uniform fine cell structure will not be obtained well, but sufficient thermal insulation performance will be obtained. I had the problem of not losing.

In addition, in the invention disclosed in Patent Document 4, polystyrene is mainly used as the thermoplastic resin in the examples. When foaming a polyolefin resin having crystallinity as compared with amorphous polystyrene, it is usually caused by crystal melting. Influenced by the characteristics of the crystalline resin that the melt viscosity and the melt tension rapidly decrease, a significant decrease in viscosity and a decrease in melt tension occur in the resin composition during foaming, and the bubbles (cells) cannot grow sufficiently, resulting in breakage. Occurs. That is, since a cell cannot grow sufficiently, it has a problem that the foam which has a uniform fine cell structure is not obtained by 10 times or more high foaming ratio.

In particular, when the foams of Patent Documents 2 and 3 are used for the heat insulating material for building materials, since a foaming ratio of 10 times or more cannot be obtained, a problem arises when the material is actually used as a heat insulating material for a building or the like. That is, because of the low expansion ratio, increasing the thickness of the heat insulating material causes the weight of the heat insulating material to become too large, and in order to improve the heat insulating performance as the member, problems such as an increase in the total weight of the member and an increase in the raw material cost are not practical. . Moreover, if an average cell diameter is 200 micrometers or less, More preferably, 100 micrometers or less is not obtained, since it becomes large to the level which can not ignore the convection effect of gas inside a cell which is one of the factors which worsen heat insulation performance, it is unpreferable. That is, it did not fully satisfy the unique requirements of building thermal insulation materials that exhibit light weight and stable thermal performance.

Accordingly, an object of the present invention is to provide a foam board for thermal insulation building materials of a polyolefin-based resin composition which has excellent extrusion foamability, has excellent heat insulation performance, can be recycled, and can be continuously produced at low cost stably. Is in.

Means to solve the problem

The present invention is a polyolefin-based resin containing a polypropylene-based resin, polyolefin-based resin containing a linear polypropylene-based resin having a specific range of melt tension as a result of earnest research and development to achieve the above object By melt-extruding the composition with a foaming agent containing at least carbon dioxide in a supercritical state, it is preferable to find that a foam board for thermal insulation building materials having a foam ratio of 10 times or more, which has not been conventionally obtained, is obtained. It has reached the invention.

In this way, this invention has the summary characterized by the following.

(1) The foaming ratio is 10 times the polyolefin resin composition containing the linear polypropylene resin whose melt tension at 230 degreeC is 5-30 g using the foaming agent containing carbon dioxide of a supercritical state at least. Foamed board for thermal insulation building materials, characterized in that the foaming is carried out.

(2) Foam board for thermal insulation building materials as described in said (1) which has a uniform cell diameter distribution whose average cell diameter is 200 micrometers or less, and a cell diameter distribution coefficient is 30% or less.

(3) Foaming for thermal insulation building materials according to the above (1) or (2), wherein a linear polypropylene resin having a melt tension at 230 ° C of 5 to 30 g is contained in the polyolefin resin composition by 50 mass% or more. board.

(4) The foaming board for thermal insulation building materials according to any one of (1) to (3), wherein the thermal conductivity measured in accordance with JIS-A1412 is 20 to 40 mW / mK.

(5) The foaming board for thermal insulation building materials according to any one of (1) to (4), wherein the thermal conductivity measured in accordance with JIS-A1412 is 20 to 37 mW / mK.

(6) A polyolefin resin composition containing a linear polypropylene resin having a melt tension of 5 to 30 g at 230 ° C. using an extruder and a foaming device having a die attached to the tip, and a supercritical state The foaming agent containing at least carbon dioxide is melt-extruded at the temperature conditions of 160-250 degreeC, the resin pressure immediately near die opening is discharged to 6-20 MPa in air | atmosphere, and extrusion foaming manufacture of the foaming board for thermal insulation building materials characterized by the above-mentioned. Way.

(7) The manufacturing method of the foaming board for thermal insulation building materials as described in said (6) which discharge | releases resin pressure in the immediate vicinity of a die opening to 7-15 Mpa, and extrusion-foams.

(8) The manufacturing method of the foaming board for heat insulating building materials as described in said (6) or (7) whose extruder is a tandem type extruder whose extrusion discharge amount is 1-1000 kg / hr.

Effects of the Invention

According to the present invention, there is provided a foam board for thermal insulation building materials of a polyolefin-based resin composition which has excellent extrusion foamability, has excellent heat insulating performance, can be recycled, and can be stably produced at low cost.

Implement the invention  Best form for

The polyolefin resin in the polyolefin resin composition of the present invention contains a polypropylene resin, and the polypropylene resin has a melt tension (MT) of 5 to 30 g at 230 ° C. Melt tension can be calculated | required here by measurement temperature 230 degreeC, extrusion speed 10mm / min, and take-up speed 3.1m / min using a caprograph. If the melt tension is less than 5 g, cell breakage is likely to occur at the time of foaming. On the contrary, if the melt tension is more than 30 g, the melt tension is too high, elongation of the cell membrane is suppressed, and sufficient cell growth is not performed at the time of foaming. It is difficult to obtain a foam having a sufficient expansion ratio, which is undesirable. Melt tension becomes like this. Preferably it is 6.5-20g, More preferably, it is 7.5-10g.

Moreover, it is preferable that the relationship of the melt tension at 230 degreeC and the melt flow rate (MFR) at 230 degreeC of the said polypropylene resin satisfy | fills following formula (I).

Log (MT)> -1.33log (MFR) + 1.2 (I)

When the melt tension and MFR of the polypropylene resin contained in the polyolefin resin composition in the present invention satisfy the above formula (1), the melt fluidity of the resin increases simultaneously with the increase of the melt tension, and the foaming can be performed. It is very preferable because the resin pressure at the time of extrusion is appropriately maintained, and sufficient elongation of the cell membrane is obtained at the time of foaming, and a foam of high magnification can be easily obtained.

In the polyolefin resin composition of this invention, in addition to the polypropylene resin which has the said specific characteristic, other resin can be contained. However, even when it contains other resin, the said polypropylene resin which has the said specific melt tension and preferably specific MFR is 50 mass% or more in the polyolefin resin composition of this invention, In particular, it is preferable to contain 80 mass% or more in order to achieve the objective of this invention favorably. When content of polypropylene resin in the said mixed resin is less than 50 mass%, the mechanical strength and heat resistance of the foam obtained may become inadequate.

As resin of that excepting the above contained in the polyolefin resin composition of this invention, the polyethylene resin, the homopolymer of propylene, the copolymer of alpha-olefins other than propylene copolymerizable with propylene and this propylene is mentioned, for example. Although it does not specifically limit as an alpha olefin, For example, ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1- pentene, 1-heptene, 1-octene etc. are mentioned. As resin other than these, you may use individually and may use it in combination of two types. Among the resins other than the above, copolymers of propylene and ethylene mainly composed of propylene homopolymer and propylene having a relatively high molecular weight in terms of excellent extrusion foamability and performance of the foam obtained, polypropylene resin and polyethylene Mixed resins of the system resin are preferably used.

It is preferable that the polypropylene resin which has the said specific characteristic, and resin other than that used with this polypropylene resin contained in the polyolefin resin composition of this invention are all substantially linear. In the present invention, the straight chain means a propylene monomer and each of the molecular chains of the propylene polymer (propylene polymer) constituting the polypropylene resin is a structural unit of the propylene polymer (propylene polymer); The copolymerizable α-olefin monomer is substantially an aggregate of those polymerized into one string with each other. Thereby, since it does not have substantially the crosslinked structure using chemical bridge | crosslinking, electron beam bridge | crosslinking, etc., and graft structures, such as a long chain branch, manufacture and quality control are comparatively easy, and repelletization etc. which are performed at the time of recycling are carried out. The thermal history of ash 3 received in the step is also preferably used because deterioration of the molecular structure is hardly caused.

The foaming board for building materials in the present invention is foamed using a foaming agent containing at least carbon dioxide in a supercritical state. Such foaming is preferably 4 to 20 parts by mass, particularly preferably 5 to 15 parts by mass, of a blowing agent containing carbon dioxide in a supercritical state with respect to 100 parts by mass of the polyolefin resin composition. When the amount of carbon dioxide used is less than 4 parts by mass, a decrease in the expansion ratio is likely to occur, and when it exceeds 20 parts by mass, large voids (voids) due to excess carbon dioxide are likely to occur in the foam, which is not preferable.

The polyolefin-based resin composition used in the present invention contains a polypropylene-based resin having the above-described specific physical properties, but the polyolefin-based resin composition may, as necessary, within a range that does not inhibit the achievement of the present invention. Antioxidants (antiaging agents) such as phenolic, phosphorus, amine, sulfur, heat stabilizers, light stabilizers, ultraviolet absorbers, phosphorus, nitrogen, halogens, antimony-based flame retardants, lubricants, antimetallic agents, antistatic agents, 1 type, or 2 or more types of various additives, such as a filler, a coloring agent, a cell nucleating agent, and a crystal nucleating agent, may be added.

Examples of the cell nucleating agent include, but are not particularly limited to, talc, calcium carbonate, clay, kaolin, mica, magnesium oxide, zinc oxide, carbon black, glass, quartz, silica, alumina, novaculite, hydrated alumina, and iron. Iron oxide, silicon dioxide, titanium oxide and the like.

Moreover, although it does not specifically limit as said crystal nucleating agent, Generally, a rosin-type crystal nucleating agent, a sorbitol type crystal nucleating agent, and a phosphate ester salt type crystal nucleating agent are mentioned. The rosin-based crystal nucleating agent may be a rosin-based resin, and is not particularly limited. For example, dibenzylidene sorbitol (DBS) manufactured by Shin-Nippon Rika Co., Ltd. may be mentioned. Although a phosphate ester salt crystal nucleus is not specifically limited, For example, Asahi telephone industry Co., Ltd. product NA-11 etc. are mentioned. You may use these crystal nucleating agents individually or in combination.

The foam board for thermal insulation building materials of this invention uses the foaming apparatus which has the die attached to the extruder and the front end, The polyolefin resin composition containing the linear polypropylene resin which has the said specific physical property, and a supercritical system A blowing agent containing at least carbon dioxide in a state is mixed and melt-extruded at a temperature of 160 to 250 ° C to prepare. If the melt extrusion temperature is less than 160 ° C., dissolution and diffusion of supercritical carbon dioxide in the resin will be reduced. On the contrary, if it exceeds 250 ° C., deterioration such as molecular chain breakdown due to heat of the polypropylene resin will start. . In addition, the resin pressure (pressure loss) immediately near the die opening in the extruder is preferably discharged into the atmosphere at 6 to 20 MPa, extruded, and foamed. Especially, it is more preferable that it is 7-15 MPa, and, as for the said pressure loss, it is most preferable that it is 9-15 MPa. If the pressure loss is less than 6 MPa, the supercritical carbon dioxide dissolved in the polyolefin resin composition tends to vaporize inside the extruder and the die, and foaming occurs inside the apparatus, resulting in cell foaming, excessive growth, and foaming. The fall of magnification and the fall of remarkable external appearance generate | occur | produce, and are not preferable. On the other hand, if the pressure loss exceeds 20 MPa, large shear is easily applied to the cell at the time of cell formation in foaming, resulting in cell breakage and unevenness of the cell structure, which is undesirable. Incompleteness of such a cell structure becomes a big obstacle in order to show sufficient thermal performance as a foam board for heat insulation building materials.

As for the extrusion discharge amount in an extruder, 1-1000 kg / hr is preferable. Especially, although extrusion ejection amount changes also with the specification of an extruder, in the type with a comparatively small screw diameter, 1-50 kg / hr is generally preferable, and in the type with a comparatively large screw diameter, it is generally 20-1000 kg. / hr is preferred. If the discharge amount is too large or too small, it is difficult to maintain a pressure loss suitable for foaming at the die site, and a foam having a sufficient magnification cannot be obtained, or the cell is broken.

Regarding the extruder to be used, the screw diameter (D) is preferably 40 to 80 mm, and when the length of the screw is (L), (L / D) is preferably 15 to 40 two screws in series. Tandem extruders configured on the basis of combining are preferred. By using a tandem extruder, the resin pressure loss condition and the discharge amount of the die site suitable for foaming can be controlled independently by the rotation speed of each screw, and the characteristic of the polyolefin resin composition of the present invention mentioned above is fully exhibited, It is possible to produce foam boards with good properties.

The die used in the extruder is not related in shape, but it is preferable that the number, shape, and thickness of the openings are designed so that the pressure loss of the openings per piece is 6 to 20 MPa as described above. For example, slit dies, Or multi-hole dies. By selecting the dice which satisfy these conditions, the foam board for heat insulation building materials which exhibits sufficient thermal performance can be obtained.

Moreover, it is preferable that the die | dye opening part in an extruder is circular, and, as for the diameter of the opening part, 0.1-2.0 mm is preferable and 0.3-0.7 mm is more preferable from a viewpoint of the external appearance of the molded object after foaming, and the ease of shape adjustment. . 0.1-10 mm is preferable and, as for the depth of dice | dies, it is preferable that a plurality of openings are provided on the dice | dies whole surface.

If the diameter is less than 0.1 mm, the strand diameter of the foam structure is too small, and it is not easy to be broken at the time of take-up, and if it exceeds 2.0 mm, the diameter of the strand is too large to make board-shaped postforming for showing smoothness. Not desirable Moreover, the slit-shaped dice etc. of width 0.1-2.0 mm and length 0.1-1000 mm can also be used.

As a specific example of the manufacturing method of the foam board for thermal insulation building materials of the present invention, the polyolefin resin composition may be formed using, for example, an extruder equipped with a carbon dioxide supply line from a supercritical carbon dioxide supply in the middle of a cylinder barrel. After the polyolefin resin composition is heated to a predetermined temperature and uniformly melt kneaded, a foam board is produced by supplying a predetermined amount of supercritical carbon dioxide from a supply line and extruding it into a board shape.

In addition, you may perform adjustment of a shape and adjustment of a size using a cutting machine, an insertion conveyor, etc., in order to prepare the product form of the foam board for heat insulation building materials, as needed.

In addition, if necessary, one or both surfaces of the foam board may be, for example, a sheet, such as an aluminum sheet, a nonwoven fabric, or a leather, as a face material, and various performances such as strength, heat resistance, and flame resistance may be provided.

Thus, even if it is 10 times or more of foaming magnifications, the foaming board for heat insulation building materials of this invention can have a cell diameter and cell distribution coefficient mentioned later, and even if it is 15 times or more, especially 20 times or more of foaming magnifications, It is preferable because it has the cell diameter and the cell distribution coefficient and has sufficient member thermal performance. Moreover, it is preferable to set it as high foaming magnification because the specific gravity of a foam can be made small and the cost of the raw material to be used can also be made small. On the other hand, when the foaming ratio is excessively high, the mechanical strength of the foam decreases, and when used as a building material application, for example, the foam tends to be damaged by external addition during construction, which is not preferable. Therefore, the expansion ratio is preferably 100 times or less, particularly 50 times or less.

Moreover, the foam board for heat insulation building materials of this invention is 200 micrometers or less in average cell diameter, It is preferable that it is 150 micrometers or less, Furthermore, it is possible to set it as 50-100 micrometers, Moreover, cell diameter distribution coefficient is 30% or less, More preferably, it is 25% or less, Especially it is possible to make it 20% or less. When the said average cell diameter is 200 micrometers or less and the said cell diameter distribution coefficient is 30% or less, it is especially preferable that it is excellent in heat insulation performance when used as a building material.

In addition, in this invention, an average cell diameter is the length of a real 2mm randomly from the image observed by cutting a foam into test piece, and observing it with the magnification of 50 times with the electron microscope (SEM). It can obtain | require by drawing 10 straight lines which correspond to, and counting the number of cells on the straight line, and calculating an average cell diameter by a following formula.

 (Average cell diameter μm) = (2000 × 10) / (number of cells on 10 straight lines)

In the present invention, the cell diameter distribution coefficient is an average value of the cell diameters of 10 to 20 cells, from an image observed by cutting the foam into test pieces and having a cross-sectional area of 50 times magnification with an electron microscope (SEM). , And the standard deviation of the cell diameters are calculated, and based on these values, the cell diameter distribution coefficient can be obtained by the following equation.

 (Cell distribution coefficient%) = (standard deviation of cell diameter) / (average value of cell diameter) × 100

Moreover, as for the foam board for heat insulation building materials of this invention, the thermal conductivity measured based on JIS-A1412 will be 20-40 mW / mK, and the foam board for heat insulation building materials which has preferable heat insulation can be obtained. Moreover, it is more preferable that heat conductivity is 20-37mW / mK. When the thermal conductivity exceeds 40 mW / mK, not only the heat insulation performance is lowered, but also the thickness of the heat insulation building material board must be 36 mm or more in order to obtain a heat resistance value of 0.9 or more, which is an evaluation criterion of heat performance desirable as an insulation building material board. When using this as a commercial heat insulating material, for example, it becomes beyond the dimension of the wooden frame of a floor, and may generate a problem at the time of construction, and it is unpreferable.

In order to demonstrate this invention further in detail, an Example is given to the following, but this invention is not limited only to these Examples.

Example 1

A supercritical carbon dioxide feeder (CO2-3, manufactured by Kawata Co., Ltd.) at the first stage of a polypropylene resin A having an MFR of 230 (3.3 ° C.) at 3.3 ° C and a melt tension of 7.6 g at 230 ° C. Tandem type single screw extruder KGT-50-made by Kawata Co., Ltd., equipped with a carbon dioxide supply line from the product, and equipped with a die 1 (8 × 48 rows of multi-hole dice having an opening diameter of 0.5 mm) at the second end. 65), the amount of carbon dioxide was set at 1.2 kg / hour, the extrusion amount was adjusted to the number of screw rotations of the first stage extruder so as to contain 6 parts by mass with respect to 100 parts by mass of the polypropylene resin, and the die (1) site. The foam board (1) for thermal insulation building materials of the polyolefin-based resin composition was obtained by adjusting the screw speed of the second-stage extruder so that the resin pressure of the resin pressure was 8.7 MPa and extruding it.

Example 2

The carbon dioxide supply amount was set at 1.5 kg / hour, the extrusion amount was adjusted to the screw rotation speed of the first stage extruder so as to contain 7.5 parts by mass with respect to 100 parts by mass of the polypropylene resin A, and the resin pressure at the die (1) site. The foaming board (2) for thermal insulation building materials of the polyolefin-based resin composition was obtained in the same manner as in Example 1 except that it was adjusted to the screw rotation speed of the second stage extruder so as to be 8.9 MPa.

Example 3

The carbon dioxide supply amount was set at 1.8 kg / hour, the extrusion amount was adjusted to the screw rotation speed of the first stage extruder so as to contain 9 parts by mass with respect to 100 parts by mass of polypropylene-based resin A, and the resin pressure at the die (1) site. The foaming board (3) for thermal insulation building materials of the polyolefin-based resin composition was obtained in the same manner as in Example 1 except that it was adjusted to the screw rotation speed of the second stage extruder so as to be 9.2 MPa and extruded and foamed.

Example 4

The carbon dioxide supply amount was set at 1.9 kg / hour, the extrusion amount was adjusted to the screw rotation speed of the first stage extruder so as to contain 6 parts by mass with respect to 100 parts by mass of the polypropylene-based resin A, and the resin pressure at the die (1) site. The foam board 4 for heat insulating building materials of the polyolefin resin composition was obtained in the same manner as in Example 1 except that it was adjusted to the screw rotation speed of the second stage extruder so as to be 8.8 MPa and extruded and foamed.

Example 5

The carbon dioxide supply amount was set at 1.2 kg / hour, and the extrusion amount was adjusted to the screw rotation speed of the first stage extruder so as to contain 6 parts by mass with respect to 100 parts by mass of the polypropylene-based resin B having a melt tension of 230 g at 230 ° C. The foam board for thermally insulating building materials of the polyolefin-based resin composition was prepared in the same manner as in Example 1 except that the resin pressure at the die A portion was adjusted to the screw rotation speed of the second stage extruder so as to be 8.8 MPa. Got.

Example 6

Except having made resin pressure of the die | dye (1) site | part into 6.5 Mpa, it carried out similarly to Example 1, and obtained the foam board 6 for heat insulation building materials of a polyolefin resin composition.

Example 7

As the polyolefin resin composition, polypropylene resin A (45 parts by mass, polypropylene resin C (homo polypropylene resin)) having a MFR of 6 g / 10 min at 230 ° C and a melt tension of 1.8 g at 230 ° C 55 The foam board (7) for heat insulating building materials of the polyolefin resin composition was obtained in the same manner as in Example 1 except that the resin pressure at the die (1) site was set to 8. 5 parts by mass.

Example 8

Except having made the resin pressure of the die | dye (1) site | part into 16.1 MPa, it carried out similarly to Example 1, and obtained the foam board (8) for heat insulating building materials of a polyolefin resin composition.

Comparative Example 1

Polypropylene-based resin C (Homopolypropylene-based resin) having an MFR of 6 g / 10 min at 230 ° C. and a melt tension of 1.8 g at 230 ° C. was fed to the same tandem single screw extruder used in Example 1 The amount of carbon dioxide was set at 1.2 kg / hour, and the extrusion amount was adjusted to the screw rotation speed of the first stage extruder so as to contain 6 parts by mass with respect to 100 parts by mass of the polypropylene resin, and the resin pressure at the die 1 site was 4.5. The foam board 6 for heat insulation building materials of a polypropylene resin composition was obtained by adjusting by the screw rotation speed of a 2nd stage extruder so that it might become MPa, and extrusion foaming.

Comparative Example 2

MFR at 230 ° C was 3.3 g / 10 min, and polypropylene-based resin A having a melt tension at 230 ° C of 7.6 g was fed to the same tandem single screw extruder used in Example 1, and the carbon dioxide supply amount was 1.2. The extrusion amount was adjusted to the screw rotation speed of the 1st stage extruder so that 6 mass parts may be contained with respect to 100 mass parts of polypropylene resins at the time of kg / hour, and dice | dies 2 (8 * 48 rows of multiholes with a diameter of opening part of 0.8 mm) The foam board (7) for thermal insulation building materials of the polypropylene resin composition was obtained by adjusting the screw rotation speed of a 2nd-stage extruder so that resin pressure of a die | dye) site | part may be 5.1 Mpa, and extrusion foaming.

Comparative Example 3

The performance was evaluated about the commercial polyethylene foam board manufactured by the bead method of foaming ratio 90 times.

Polyolefin (polypropylene) -based resin foams obtained in Examples 1 to 5 and Comparative Examples 1 and 2, and Comparative Example 3 performances of polyethylene foam boards ((a) Density, ( b) compressive strength, (c) average cell diameter, (d) thermal conductivity, and (e) cell diameter distribution coefficient) were evaluated by the following method.

(a) density. The obtained foam was cut into 20 x 20 x 2.5 (cm) test pieces, the weight and the length of each side were measured, and the foam density was determined according to the following calculation formula.

(Foam density G / L) = (foam weight G) / (foam volume L)

(b) compressive strength. In accordance with JISK-6767 (polyethylene foam test method), 25% compression hardness (kPa) of the foam was measured.

(c) average cell diameter... The foam is cut into test pieces and the cross-sectional area thereof is randomly selected from the image observed at 50 times magnification with an electron microscope (SEM) using SEM Super Scan 220 manufactured by Shimadzu Corporation. By drawing 10 corresponding straight lines and counting the number of cells on the straight lines, the average cell diameter was calculated and calculated by the following equation.

(Average cell diameter μm) = (2000 × 10) / (number of cells on 10 straight lines)

(d) thermal conductivity. Based on JISA-1412, the obtained foam was cut into the test piece of 20 * 20 * 2 (cm), and thermal conductivity was measured using the thermal conductivity measuring apparatus HC-074 by the Eco company.

(e) cell diameter distribution coefficient. The obtained foam was cut into test pieces, and the cross-sectional area thereof was observed at a magnification of 50 times using SEM Super Scan 220 manufactured by Shimadzu Corporation, and the cell diameter average value and standard deviation of the cell diameter of about 10 to 20 cells. Was calculated. Based on these values, the cell diameter distribution coefficient was calculated by the following formula.

(Cell diameter distribution coefficient) = (standard deviation of cell diameter) / (average value of cell diameter)

(f) melt tension. It calculated | required by the measurement temperature of 230 degreeC, the extrusion speed of 10 mm / min, and the take-out speed of 3.1 m / min using the Capirograph 1C (made by Toyo Seisakusho). In addition, the orifice of length 8mm and diameter 2.095mm was used for the measurement.

(g) foam ratio. It calculated | required according to the following formula from the measurement result of the specific gravity of resin and the density obtained by (a).

(Foam ratio) = (density of resin) / (density of foam)

Table 1 puts together the compounding composition used by this invention, extrusion conditions, and the physical property of the obtained foam.

The foam of the polyolefin resin composition of the present invention can be widely used mainly for thermal insulation building materials, automobile members, packaging cushioning materials, and the like, by utilizing its excellent performance and balance of cost, and further, excellent recycling properties.

In addition, all the content of the JP Patent application 2005-192375, a claim, drawing, and the abstract for which it applied on June 30, 2005 is referred here, and it introduces as an indication of the specification of this invention.

Claims (8)

The polyolefin resin composition containing a linear polypropylene resin having a melt tension of 5 to 30 g at 230 ° C. is foamed at least 10 times by using a foaming agent containing at least carbon dioxide in a supercritical state. Foam board for insulating building materials, characterized in that made. The method of claim 1, The foam board for heat insulation building materials which has a uniform cell diameter distribution whose average cell diameter is 200 micrometers or less, and a cell diameter distribution coefficient is 30% or less. The method according to claim 1 or 2, The foam board for thermal insulation building materials which 50 mass% or more of linear type polypropylene resin whose melt tension in 230 degreeC is 5-30 g is contained in the said polyolefin resin composition. The method according to any one of claims 1 to 3, Foam board for thermal insulation building materials having a thermal conductivity of 20 to 40 mW / mK, measured according to JIS-A1412. The method according to any one of claims 1 to 4, Foam board for thermal insulation building materials having a thermal conductivity of 20 to 37 mW / mK measured according to JIS-A1412. By using an extruder and a foaming apparatus having a die attached to the tip, a polyolefin resin composition containing a linear polypropylene resin having a melt tension of 5 to 30 g at 230 ° C. and carbon dioxide in a supercritical state Melt-extrusion of the foaming agent containing at least on the temperature conditions of 160-250 degreeC, the resin pressure immediately near die opening is discharged to 6-20 MPa to air | atmosphere, and extrusion foaming is a manufacturing method of the foaming board for thermal insulation building materials characterized by the above-mentioned. The method of claim 6, A method for producing a foam board for thermal insulation building materials, characterized by releasing the resin pressure in the vicinity of the die opening to 7 to 15 MPa into the atmosphere and extrusion foaming. The method according to claim 6 or 7, The extruder is a manufacturing method of the foam board for heat insulation building materials which is a tandem type extruder whose extrusion discharge amount is 1-1000 kg / hr.