CN101203552A - Foam board for heat insulation building material and manufacturing method 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 heat insulation building material and manufacturing method thereof

technical field

The present invention relates to a foamed board for heat-insulating building materials made of a polyolefin resin composition and a manufacturing method thereof.

Background technique

Foams of polyolefin resin compositions are widely used mainly for heat-insulating building materials and automobile parts due to their good balance between performance and cost, as well as the recyclability of resins that have been advocated in recent years. , Packaging and cushioning materials, etc.

For example, as a thermal insulation building material, foamed boards made of polypropylene resin and polyethylene resin are applied inside floors or walls of buildings, exhibit good thermal insulation performance, and are widely accepted in the market.

Foams of these polyolefin resin compositions are widely used in society as very useful raw materials in this way, and many studies on their production methods have been carried out. Conventionally, methods for producing foams of polyolefin resin compositions are roughly classified into two types.

Among them, the first type of production method is called the so-called bead method, which is to impregnate a foaming agent such as a hydrocarbon into a polyolefin resin dispersed in water or the like in a pressurized airtight container under high temperature and high pressure. It is a method in which the pre-expanded particles are filled in a mold and heated and cooled to obtain an in-mold molded product.

The foamed board of the polyolefin resin composition can also be produced by the bead method, but the average cell diameter of the foam produced by the usual bead method is as large as about 200-500 μm, and it is impossible to obtain thermal insulation as a thermal insulation building material. Fully functional material. In addition, the bead method is a batch production method, and steam in-mold molding is required after the particle manufacturing process and the pre-expanded particle manufacturing process. Therefore, the number of production steps and energy consumption are large, and continuous production is not possible, so there is a problem of high manufacturing costs. shortcoming.

The second production method is called the so-called extrusion method, which is to inject polyolefin resin composition particles into an extruder, and use hydrocarbons or chemical foaming agents as foaming agents as needed, and carry out under heat and pressure. After melt-kneading, a foam is obtained by passing a mold designed into a predetermined shape.

For this extrusion method, for example, Patent Document 1 discloses that a polyfunctional monomer and a thermally decomposable foaming agent are added to a polypropylene resin, melt-mixed in advance, and irradiated with electron beams to crosslink the polypropylene resin. A method of reheating to decompose a pyrolytic foaming agent to make it foam, etc.

In addition, in the extrusion method described in Patent Document 2, by molding a polypropylene resin composition having the following characteristics (1) to (4) containing polypropylene as a main component, it is possible to obtain a product with good appearance and rigidity. Various large molded products. That is, it discloses a polypropylene resin composition having (1) a melt flow rate (MFR) measured under a load of 2.16 kg at 230° C. of 0.01 to 5 g/10 minutes, and (2) measured in decalin at 135° C. The content of high molecular weight polypropylene with an intrinsic viscosity [η] of 8 to 13dl/g is 15 to 50% by weight, (3) the number of gels is below 3000/450cm ² , (4) by gel permeation chromatography The molecular weight distribution Mw/Mn measured by (GPC) is 6-20 and Mz/Mw is more than 3.5, so that high-speed molding can be efficiently obtained with high melt tension, good formability, good rigidity, good appearance, and large-scale molding that is not easily deformed. Taste.

In addition, Patent Document 3 discloses a foamed molded article of a thermoplastic polymer obtained by foaming a thermoplastic polymer composition with a high expansion ratio of 2 times or more, fine and uniform bubble size, and good extrusion stability. The composition comprises a thermoplastic polymer (A) and 10 to 50% by weight of an ultra-high molecular weight polyolefin (b-1) with an intrinsic viscosity [η] of 10 to 40 dl/g and 90 to 50% by weight of an [η] of 0.1 to 0.1 Weight of polyolefin composition (B), (A) and (B) of 5 dl/g of polyolefin (b-2) [sum of (b-1) and (b-2) is taken as 100% by weight] The ratio [(A)/(B)] is 95/5 to 60/40.

In addition, Patent Document 4 discloses a method for producing a thermoplastic resin foam including the steps of melting a resin composition composed of a thermoplastic resin and a fluoroalkyl ester of an aliphatic carboxylic acid in an extruder, and adding The inert gas in the supercritical state of the agent forms a gas dissolution process in which the thermoplastic resin composition and the inert gas are in a completely miscible state; in the extruder, the inert gas as a blowing agent is maintained at a pressure above the critical pressure. Next, the cooling process of lowering the temperature of the molten resin; the nucleation process of generating cell nuclei by releasing the pressure from a pressure above the critical pressure of an inert gas to atmospheric pressure in a mold heated above the glass transition temperature of the resin and, cooling the foam to below the glass transition temperature or crystallization temperature of the thermoplastic resin to control the foaming control process of the cell diameter.

Patent Document 1: Japanese Patent Laid-Open No. 07-173317

Patent document 2: WO99/07752 publication

Patent Document 3: Japanese Patent Laid-Open No. 2004-217755

Patent Document 4: Japanese Patent Laid-Open No. 10-175248

disclosure of invention

However, the invention described in Patent Document 1 has a problem that it is not suitable for continuous mass production because it has a molding step, a crosslinking step, and a foaming step, and the number of steps is large. In addition, in recent years, the recycling of plastic molded articles has been increasingly demanded due to environmental problems, etc. process, it is relatively easy to produce cross-linked body, decomposition of grafted body, etc., so there is no way to maintain the melting properties required for foaming and insufficient recyclability.

In addition, in the inventions disclosed in Patent Document 2 and Patent Document 3, since a foam with a relatively low expansion ratio of about 5 times can be easily obtained, it is a foam in which the air cells (cells) of the foam are uniformly dispersed. Foam, but still can not get enough insulation performance. Therefore, in order to obtain better heat insulation performance, it is considered that the expansion ratio should be more than 10 times, but if it reaches a high expansion ratio of more than 10 times, it will be difficult to obtain a foam with a uniform and fine cell structure, and it will not be possible. The problem of obtaining adequate thermal insulation performance.

In addition, in the invention disclosed in Patent Document 4, polystyrene is mainly used as the thermoplastic resin in its examples, but compared with amorphous polystyrene, the case where a crystalline polyolefin resin is foamed In general, under the influence of the characteristics of crystalline resins whose melt viscosity and melt tension drop rapidly due to the melting of crystals, the resin composition during foaming has a significant drop in viscosity and melt tension, and bubbles (cells) cannot grow sufficiently. And the problem of rupture. That is, there is a problem that a foam having a uniform and fine cell structure cannot be obtained at a high expansion ratio of 10 times or more because the cells cannot grow sufficiently.

In particular, when the foams of the above-mentioned Patent Documents 2 and 3 are used as heat insulating materials for building materials, a high expansion ratio of 10 times or more cannot be obtained. cause problems. That is, due to its low expansion ratio, if the thickness of the heat insulating material is increased, the weight of the heat insulating material is too large. In order to make the heat insulating performance of the part good, problems such as an increase in the total weight of the part and an increase in the cost of raw materials occur, is impractical. In addition, if a foam with an average cell diameter of 200 μm or less, preferably 100 μm or less can not be obtained, it will be too large to ignore the influence of gas convection inside the cells as one of the main causes of deterioration of thermal insulation performance. So it's not ideal. That is, it is not possible to fully satisfy the requirements specific to building heat insulating materials that are lightweight and exhibit stable thermal performance.

Therefore, in view of the above-mentioned problems, the object of the present invention is to provide a polyolefin resin composition with good extrusion foamability, good heat insulation performance, recyclable, low-cost, stable and continuous production. Foam board for thermal building materials.

After earnest research and development by the present inventors in order to achieve the above object, it was found that as a polyolefin resin including a polypropylene resin, a polyolefin resin composition containing a linear polypropylene resin having a melt tension within a specific range was passed through The present invention has been accomplished by melt-extruding a foaming agent containing at least carbon dioxide in a supercritical state under preferred specific conditions to obtain an unprecedented foamed board for heat-insulating building materials having an expansion ratio of 10 times or more.

Then, the present invention has the gist characterized by the following.

(1) A foamed board for heat-insulating building materials, characterized in that a foaming agent containing at least supercritical carbon dioxide is used, and a polystyrene resin containing a linear polypropylene-based resin having a melt tension of 5 to 30 g at 230°C is used. The olefin resin composition is obtained by foaming at an expansion ratio of 10 times or more.

(2) The foamed board for a heat-insulating building material according to (1) above, which has an average cell diameter of 200 μm or less and a uniform cell diameter distribution with a cell diameter distribution coefficient of 30% or less.

(3) The foamed board for heat-insulating building materials according to the above (1) or (2), wherein a linear polypropylene-based resin having a melt tension at 230° C. of 5 to 30 g is combined with the polyolefin-based resin. The content in the product is more than 50% by mass.

(4) The foamed board for heat insulating building materials in any one of said (1)-(3) whose thermal conductivity measured based on JIS-A1412 is 20-40 mW/mK.

(5) The foamed board for heat insulating building materials in any one of said (1)-(4) whose thermal conductivity measured based on JIS-A1412 is 20-37 mW/mK.

(6) A method for producing a foamed sheet for heat-insulating building materials, which comprises using a foaming device having an extruder and a die attached to the front end, and including a linear sheet having a melt tension of 5 to 30 g at 230°C. The polyolefin resin composition of polypropylene resin and the foaming agent containing at least supercritical carbon dioxide are melt-extruded at a temperature of 160 to 250°C, and the resin pressure near the die opening is released to the atmosphere at 6 to 20 MPa Next, extrusion foaming is carried out.

(7) The method for producing a foamed board for heat-insulating building materials according to (6) above, wherein the extrusion foaming is performed by releasing the resin pressure near the die opening to the atmosphere at 7 to 15 MPa.

(8) The method for producing a foamed board for a heat insulating building material according to the above (6) or (7), wherein the extruder is a tandem extruder having an extrusion output of 1 to 1000 kg/hour.

According to the present invention, it is possible to provide a foam for heat-insulating building materials that has good extrusion foamability, has good heat-insulating performance, is recyclable, and can be continuously produced stably and at low cost. plate.

The best way to practice the invention

The polyolefin resin in the polyolefin resin composition of this invention contains a polypropylene resin, and the melt tension (MT) at 230 degreeC of the said polyolefin resin must be 5-30g. Here, the melt tension can be obtained using a fluidity tester under the conditions of a measurement temperature of 230° C., an extrusion speed of 10 mm/min, and a pulling speed of 3.1 m/min. If the melt tension is less than 5g, cell rupture is likely to occur during foaming; on the contrary, if it exceeds 30g, the melt tension is too high, the elongation of the cellular film is inhibited, and sufficient cell growth cannot be performed during foaming. , so it is difficult to obtain a foam having a sufficient expansion ratio of 10 times or more, which is not preferable. The melt tension is preferably from 6.5 to 20 g, more preferably from 7.5 to 10 g.

In addition, the relationship between the melt tension at 230° C. and the melt flow rate (MFR) at 230° C. of the polypropylene-based resin preferably satisfies the following formula (I).

Log(MT)＞-1.33log(MFR)+1.2 (I)

In the present invention, when the melt tension and MFR of the polypropylene resin contained in the polyolefin resin composition satisfy the above-mentioned formula (I), the melt fluidity of the resin increases simultaneously with the increase of the melt tension, and the foaming process The resin pressure during extrusion is kept appropriate, and sufficient elongation of the cellular film can be obtained during foaming, and a high-expansion foam can be easily obtained, so it is very ideal.

The polyolefin-based resin composition of the present invention may contain other resins in addition to the above-mentioned polypropylene-based resin having specific characteristics. However, in the case of containing other resins, in order to achieve the object of the present invention well, it is desirable that the above-mentioned polypropylene-based resin having a specific melt tension and preferably a specific MFR in the polyolefin-based resin composition of the present invention The content is preferably at least 50% by mass, particularly preferably at least 80% by mass. If the content of the polypropylene-based resin in the mixed resin is less than 50% by mass, the resulting foam may have insufficient mechanical strength or heat resistance.

Examples of the other resins contained in the polyolefin resin composition of the present invention include polyethylene resins, homopolymers of propylene, and copolymers of propylene and α-olefins other than propylene that can be copolymerized with the propylene. . The α-olefin is not particularly limited, and examples thereof include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. . These other resins may be used alone or in combination of two or more. As the above-mentioned other resins, because the performance of the obtained foam is good, among them, a propylene homopolymer having a relatively high molecular weight, a copolymer of propylene and ethylene mainly composed of propylene, and a mixed resin of a polypropylene resin and a polyethylene resin are preferably used. .

The above-mentioned polypropylene-based resin having specific characteristics contained in the polyolefin-based resin composition of the present invention and other resins used together with the polypropylene-based resin are preferably substantially linear. In the present invention, linear means that each molecular chain of the propylene-based polymer constituting the polypropylene-based resin is substantially composed of the propylene monomer as the constituent unit of the propylene-based polymer and the α-olefin monomer copolymerizable therewith. Mutual aggregation into a linear aggregate. Therefore, it does not actually have a cross-linked structure such as chemical cross-linking or electron beam cross-linking or a graft structure such as long-chain branching, so manufacturing and quality control are relatively easy. It is also less likely to cause deterioration of its molecular structure due to repeated thermal processes in the process, so it can be used well.

The foamed board for building materials of the present invention is foamed using a foaming agent containing at least carbon dioxide in a supercritical state. For the foaming, it is desirable that the amount of the blowing agent containing carbon dioxide in a supercritical state is preferably from 4 to 20 parts by mass, particularly preferably from 5 to 15 parts by mass, based on 100 parts by mass of the polyolefin resin composition. If the amount of carbon dioxide used is less than 4 parts by mass, the expansion ratio will easily decrease; if it exceeds 20 parts by mass, large voids caused by excessive carbon dioxide will easily appear in the foam.

The polyolefin-based resin composition used in the present invention contains the aforementioned polypropylene-based resin having specific physical properties, and within the scope of not impairing the realization of the object of the present invention, one or more of them may be added to the polyolefin-based resin composition as required. More than 2 kinds of various additives, the additives include antioxidants (anti-aging agents) such as phenols, phosphorus, amines, sulfur, etc., heat stabilizers, light stabilizers, ultraviolet absorbers, phosphorus, nitrogen , halogen-based, antimony-based flame retardants, lubricants, anti-metal poisoning agents, antistatic agents, fillers, colorants, cell nucleating agents, crystallization nucleating agents, etc.

The above-mentioned cell nucleating agent is not particularly limited, and examples thereof include talc, calcium carbonate, clay, kaolin, mica, magnesium oxide, zinc oxide, carbon black, glass, quartz, silica, alumina, uniform quartzite, hydrated Aluminum oxide, iron, iron oxide, silicon dioxide, titanium oxide, etc.

In addition, the above-mentioned crystal nucleating agent is not particularly limited, and generally, a rosin-based crystal nucleating agent, a sorbitol-based crystal nucleating agent, and a phosphate ester salt-based crystal nucleating agent may be exemplified. The rosin-based crystal nucleating agent is not particularly limited as long as it is a rosin-based resin, and examples thereof include dibenzylidene sorbitol (DBS) manufactured by Shin Nippon Rika Co., Ltd., and the like. The phosphate salt-based crystallization nucleating agent is not particularly limited either, and for example, NA-11 by Soden Chemical Industry Co., Ltd. may, for example, be mentioned. These crystal nucleating agents may be used alone or in combination.

The foamed sheet for heat-insulating building materials of the present invention uses a foaming device having an extruder and a die attached to the front end to make the polyolefin-based resin composition containing the above-mentioned linear polypropylene-based resin having specific physical properties and at least The blowing agent of supercritical carbon dioxide is mixed, melted and extruded under the temperature condition of 160-250°C to foam. If the melt extrusion temperature is less than 160°C, the dissolution and diffusion of supercritical carbon dioxide into the resin will be poor; on the contrary, if it exceeds 250°C, the deterioration of the molecular chain of the polypropylene resin will begin to occur due to heat-induced molecular chain scission. So it's not ideal. In addition, the resin pressure (pressure drop) in the vicinity of the die opening in the extruder is preferably released to the atmosphere at 6 to 20 MPa to perform extrusion foaming. Among them, the above pressure drop is more preferably 7 to 15 MPa, most preferably 9 to 15 MPa. If the pressure drop is less than 6 MPa, the supercritical carbon dioxide dissolved in the polyolefin resin composition is likely to gasify inside the extruder and the inside of the die, and foaming occurs inside the device, resulting in a combination of cells, Excessive growth, decrease in expansion ratio, and significant decrease in appearance are undesirable. On the other hand, if the pressure drop exceeds 20 MPa, when cells are formed during foaming, large shearing tends to occur in the cells, resulting in cell rupture and non-uniform cell structure, which is not preferable. Incompleteness of such a cell structure becomes a great obstacle to expressing sufficient thermal performance as a foamed board for heat insulating building materials.

The extrusion discharge rate in the extruder is preferably from 1 to 1000 kg/hour. Among them, the extrusion discharge rate varies depending on the type of extruder, preferably about 1 to 50 kg/hour for a type with a small screw diameter, and about 20 to 1000 kg/hour for a type with a large screw diameter. If the discharge amount is too large or too small, it will be difficult to maintain a pressure drop suitable for foaming at the mold part, and it will not be possible to obtain a sufficient multiple of the foam or the cells will be broken.

The extruder to be used is ideally a series connection of two screws with a screw diameter (D) of preferably 40 to 80 mm and a screw length (L) of (L/D) preferably of 15 to 40. Combination-based tandem extruder. By using a tandem extruder, it is possible to independently control the resin pressure drop condition and the discharge amount of the mold part suitable for foaming by the rotation speed of each screw, and the above-mentioned characteristics of the polyolefin resin composition of the present invention are fully exerted, Foamed panels with good properties can be manufactured.

The shape of the die used in the extruder is not limited, but it is desirable to design the number, shape, and thickness of the openings so that the pressure drop of each opening reaches the above-mentioned 6-20 MPa. For example, narrow Slit die or porous die, etc. By selecting a mold that satisfies such conditions, a foamed board for a heat-insulating building material exhibiting sufficient thermal performance can be obtained.

In addition, from the viewpoint of the appearance of the molded product after foaming and the ease of obtaining the shape, the die opening of the extruder is preferably circular, and the diameter of the opening is preferably from 0.1 to 2.0 mm, more preferably It is 0.3-0.7 mm. The depth of the mold is preferably from 0.1 to 10 mm, and it is preferable to have a plurality of openings on the front surface of the mold.

If the aforementioned diameter is less than 0.1mm, the diameter of the bundle formed by the foam is too small, and it is easy to break when pulled, which is not ideal; if it exceeds 2.0mm, the diameter of the bundle is too large, and it is used to achieve smoothness. Postforming is difficult and is not ideal. In addition, a slit-shaped die having a width of 0.1 to 2.0 mm and a length of 0.1 to 1000 mm may be used.

As a specific example of the production method of the foamed board for heat-insulating building materials of the present invention, for example, using an extrusion molding machine equipped with a carbon dioxide supply line from a supercritical carbon dioxide supply machine in the cylinder cavity, the above-mentioned foamable polyolefin resin is combined. After heating the material to a predetermined temperature and uniformly melting and kneading, a predetermined amount of supercritical carbon dioxide is supplied from a supply pipe, and the above-mentioned polyolefin resin composition is extruded into a sheet shape to form a foamed sheet.

Moreover, in order to obtain the commercial form of the foam board for heat insulating building materials, shape adjustment and dimension adjustment can be performed using a cutting machine, a crimping conveyance apparatus, etc. as needed.

In addition, sheet-like materials such as aluminum sheets, non-woven fabrics, and leather can be laminated on one or both sides of the foam board as needed to impart various properties such as strength, heat resistance, and flame retardancy.

Therefore, the foamed board for heat insulating building materials of the present invention can have the cell diameter and cell distribution coefficient described later even if the expansion ratio is 10 times or more, and even if the foaming ratio is 15 times or more, especially 20 times or more Multiples, not only have the aforementioned cell diameter, cell distribution coefficient, but also have sufficient thermal performance of parts, so it is ideal. In addition, if a high expansion ratio is adopted, the specific gravity of the foam can be reduced and the cost of the raw materials used can be reduced, which is desirable. On the other hand, if the expansion ratio is too high, the mechanical strength of the foam will decrease. For example, in the case of building materials, the foam will be easily damaged by external force during construction, which is not preferable. Therefore, the expansion ratio is preferably at most 100 times, particularly preferably at most 50 times.

In addition, the average cell diameter of the foamed board for heat-insulating building materials of the present invention may be less than 200 μm, preferably less than 150 μm, more preferably 50-100 μm, and the distribution coefficient of cell diameter may be less than 30%, preferably 25%. Below, particularly preferably below 20%. When the average cell diameter is 200 μm or less and the cell diameter distribution coefficient is 30% or less, the thermal insulation performance is particularly good when used as a building material, which is ideal.

In addition, the average cell diameter in the present invention can be obtained by cutting the foam into small test pieces, and according to the image of its cross-sectional area observed with an electron microscope (SEM) at a magnification of 50 times, randomly draw 10 lines with a length of substantially 2 mm. The left and right straight lines are counted, and the number of cells on these straight lines is counted, and the average cell diameter is calculated from the following formula.

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

In addition, the cell size distribution coefficient in the present invention can be calculated by cutting the foam into small test pieces and observing the cross-sectional area with an electron microscope (SEM) at a magnification of 50 times to calculate the ratio of 10 to 20 cells. Based on the average value of the cell diameter and the standard deviation of the cell diameter, the cell diameter distribution coefficient was obtained from the following formula.

(Cell size distribution coefficient%)=(Standard deviation of cell size)/(Average value of cell size)×100

In addition, the thermal conductivity of the foamed board for heat-insulating building materials according to JIS-A1412 of the present invention is 20 to 40 mW/mK, and a foamed board for heat-insulating building materials having good heat-insulating properties can be obtained. In addition, the thermal conductivity is more preferably from 20 to 37 mW/mK. If the above-mentioned thermal conductivity exceeds 40mW/mK, not only the thermal insulation performance will deteriorate, but also the thermal resistance value of 0.9 or more, which is the evaluation standard of the preferred thermal performance of the thermal insulation building material board, cannot be obtained. Therefore, the thickness of the thermal insulation building material board must be within If it is more than 36mm, for example, when it is used as a heat insulating material for a floor, it is not ideal because it exceeds the size of the wooden frame of the floor and may cause problems during construction.

Example

Hereinafter, in order to describe the present invention in more detail, examples are given, but the present invention is not limited to these examples.

Example 1

A polypropylene-based resin A having an MFR of 3.3 (g/10 minutes) at 230°C and a melt tension of 7.6 g at 230°C was supplied to a supercritical carbon dioxide feeder (manufactured by Kawata Co., Ltd. CO2) installed in the first stage. -3) a carbon dioxide supply pipe, a tandem single-screw extruder (KGT-50 manufactured by Kawata Co., Ltd.) equipped with a die 1 (8 × 48 rows of porous dies with a diameter of 0.5 mm opening) at the front end of the second stage In -65), the carbon dioxide supply rate is set to 1.2kg/hour, and the extrusion rate is adjusted with the screw speed of the extruder in the first stage under the condition of containing 6 parts by mass relative to 100 parts by mass of the polypropylene resin. The resin pressure at the first part was 8.7 MPa and the screw rotation speed of the second-stage extruder was adjusted to perform extrusion foaming to obtain a foamed sheet 1 for a heat-insulating building material of a polyolefin resin composition.

Example 2

In addition to setting the carbon dioxide supply rate at 1.5 kg/hour, the extrusion rate was adjusted with the screw speed of the first-stage extruder under the condition that the polypropylene resin A contained 7.5 parts by mass relative to 100 parts by mass of the polypropylene resin, and the die 1 position The condition of the resin pressure of 8.9MPa is adjusted by adjusting the screw speed of the extruder in the second stage, except for extruding and foaming, it is carried out in the same manner as in Example 1, thereby obtaining a heat-insulating building material of a polyolefin resin composition. Use foam board 2.

Example 3

In addition to setting the carbon dioxide supply rate at 1.8 kg/hour, the extrusion rate was adjusted with the screw speed of the extruder in the first stage under the condition of containing 9 parts by mass relative to 100 parts by mass of the polypropylene resin A, and the die 1 position Under the condition that the resin pressure is 9.2 MPa, the screw speed of the extruder in the second stage is adjusted to perform extrusion and foaming, and the same implementation is carried out as in Example 1, thereby obtaining a heat-insulating building material of a polyolefin resin composition. Use foam board3.

Example 4

In addition to setting the carbon dioxide supply rate at 1.9 kg/hour, the extrusion rate was adjusted with the screw speed of the extruder in the first stage under the condition of containing 6 parts by mass relative to 100 parts by mass of the polypropylene resin A, and the die 1 position The condition of the resin pressure of 8.8MPa is adjusted by adjusting the screw speed of the extruder in the second stage, except for extruding and foaming, it is carried out in the same manner as in Example 1, thereby obtaining a heat-insulating building material of a polyolefin resin composition. Use foam board 4.

Example 5

In addition to setting the carbon dioxide supply rate at 1.2 kg/hour, the screw rotation speed of the extruder in the first stage was controlled under the condition of containing 6 parts by mass of the polypropylene-based resin B with a melt tension of 8.5 g at 230°C to 100 parts by mass. Adjust the extrusion rate, and adjust the screw speed of the extruder of the second stage under the condition that the resin pressure at the mold A position is 8.8MPa, and carry out extrusion foaming, implement the same as Example 1, thereby obtaining The foamed board 5 for heat insulating building materials of a polyolefin resin composition.

Example 6

Except that the resin pressure at the mold 1 part was 6.5 MPa, it carried out similarly to Example 1, and obtained the foamed board 6 for heat insulating building materials of a polyolefin resin composition.

Example 7

In addition to being used as a polyolefin resin composition, 45 parts by mass of polypropylene resin A and 55 parts by mass of polypropylene resin C (homopolymer) having an MFR of 6 g/10 minutes at 230° C. and a melt tension of 1.8 g at propylene-based resin), except that the resin pressure at the part of the mold 1 was set to 8.65 MPa, the same procedure as in Example 1 was carried out to obtain a foamed sheet 7 for a heat-insulating building material of a polyolefin-based resin composition.

Example 8

Except that the resin pressure at the mold 1 part was 16.1 MPa, it carried out similarly to Example 1, and obtained the foamed board 8 for heat insulating building materials of a polyolefin resin composition.

Comparative example 1

A polypropylene-based resin C (homopolypropylene-based resin) having an MFR of 6 g/10 minutes at 230° C. and a melt tension of 1.8 g at 230° C. was supplied to the same tandem uniaxial extrusion as that used in Example 1. In the extruder, the carbon dioxide supply rate was set to 1.2kg/hour, and the extrusion rate was adjusted with the screw speed of the extruder of the first stage under the condition that the polypropylene resin contained 6 parts by mass relative to 100 parts by mass of the polypropylene resin. The resin pressure at the part was 4.5 MPa, and the screw speed of the extruder in the second stage was adjusted to perform extrusion foaming to obtain a foamed sheet 6 for a heat-insulating building material of a polyolefin resin composition.

Comparative example 2

A polypropylene-based resin A having an MFR of 3.3 g/10 minutes at 230°C and a melt tension of 7.6 g at 230°C was supplied to the same tandem single-screw extruder as used in Example 1, and carbon dioxide The supply rate was set at 1.2 kg/hour, and the extrusion rate was adjusted with the screw speed of the extruder in the first stage under the condition of containing 6 parts by mass relative to 100 parts by mass of the polypropylene resin, and the diameter of the opening part of the die 2 was 0.8mm (8 × 48 rows of porous dies) position of the resin pressure of 5.1MPa is adjusted with the screw speed of the second stage of the extruder to perform extrusion foaming, so as to obtain the insulation of the polyolefin resin composition Foam board for hot building materials7.

Comparative example 3

Performance was evaluated for a commercially available polyethylene foam sheet produced by the bead method having an expansion ratio of 90 times.

Regarding the properties of the polyolefin (polypropylene) resin foams obtained in Examples 1 to 5 and Comparative Examples 1 and 2, and the polyethylene foam plates in Comparative Example 3 ((a) density , (b) compressive strength, (c) average cell diameter, (d) thermal conductivity, (e) cell diameter distribution coefficient) were evaluated by the following methods.

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

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

(b) Compression strength... According to JISK-6767 (polyethylene foam test method), the 25% compression hardness (kPa) of a foam was measured.

(c) Average cell diameter... Cut the foam into small test pieces, and randomly observe the cross-sectional area using an electron microscope (SEM) at a magnification of 50 times with SEM Superscan 220 manufactured by Shimadzu Corporation. Ten straight lines substantially about 2 mm in length were drawn, the number of cells on these straight lines was counted, and the average cell diameter was calculated from the following formula.

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

(d) Thermal conductivity... According to JISA-1412, the resulting foam was cut into test pieces of 20×20×2 (cm), and the thermal conductivity was measured using a thermal conductivity measuring device HC-074 manufactured by Eiko Seiki Co., Ltd. .

(e) Cell size distribution coefficient... Cut the foam into small test pieces, and calculate about 10 to 20 cells based on the image of the cross-sectional area observed at a magnification of 50 times with SEM Superscan 220 manufactured by Shimadzu Corporation. The average value and standard deviation of the cell diameters of the cells. Based on these values, the cell size distribution coefficient was obtained from the following formula.

(Cell size distribution coefficient)=(Standard deviation of cell size)/(Average value of cell size)

(f) Melt tension...Using a fluidity tester 1C (manufactured by Toyo Seiki Co., Ltd.), it obtained under the conditions of a measurement temperature of 230° C., an extrusion speed of 10 mm/min, and a pulling speed of 3.1 m/min. In addition, a hole with a length of 8 mm and a diameter of 2.095 mm was used for the measurement.

(g) Expansion ratio... Calculated according to the following formula from the measurement results of the specific gravity of the resin and the density obtained in (a).

(expansion ratio) = (specific gravity of resin) / (density of foam)

Table 1 summarizes the compounding composition used in the present invention, the extrusion conditions, and the physical properties of the obtained foam.

Table 1

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6   Polyolefin resin composition   Polypropylene Resin A 100 parts by mass 100 parts by mass 100 parts by mass 100 parts by mass 100 parts by mass   Polypropylene resin B 100 parts by mass   Commonly used polypropylene resin C Carbon dioxide content 6 parts by mass 7.5 parts by mass 9 parts by mass 6 parts by mass 6 parts by mass 6 parts by mass   Extruder setting first stage 50mmφ extruder Cylinder set temperature 180°C 180°C 180°C 180°C 180°C 180°C Rotating speed 70RPM 70RPM 70RPM 110RPM 70RPM 70RPM  The second stage 65mmφ extruder Cylinder set temperature 180°C 180°C 180°C 180°C 180°C 180°C Rotating speed 12RPM 12RPM 12RPM 18RPM 12RPM 10RPM Mold resin pressure 8.7MPa 8.9MPa 9.2MPa 8.8MPa 8.8MPa 6.5MPa Mold Mold 1 Mold 1 Mold 1 Mold 1 Mold 1 Mold 1 Physical Properties Foam Appearance Foam Density Foam Multiple Compression Strength Average Cell Diameter Cell Diameter Coefficient of Variation Thermal Conductivity ○ ○ ○ ○ ○ ○ 35.8G/L 33.0G/L 29.7G/L 34.9G/L 38.0G/L 39.0G/L 25 times 28 times 31 times 26 times 24 times 23 times 133kPa 130kPa 112kPa 131kPa 133kPa 135kPa 142μm 146μm 135μm 144μm 135μm 205μm 28 twenty two twenty three 25 twenty one 32 40mW/mK 39mW/mK 36mW/mK 40mW/mK 40mW/mK 41mW/mK

Table 1 (continued)

Example 7 Example 8 Comparative example 1 Comparative example 2 Comparative example 3   Polyolefin resin composition   Polypropylene Resin A 45 parts by mass 100 parts by mass 100 parts by mass   Polypropylene resin B   Commonly used polypropylene resin C 55 parts by mass 100 parts by mass Carbon dioxide content 6 parts by mass 6 parts by mass 6 parts by mass 6 parts by mass   Extruder setting first stage 50mmφ extruder Cylinder set temperature 180°C 180°C 180°C 180°C Rotating speed 70RPM 110RPM 70RPM 70RPM  The second stage 65mmφ extruder Cylinder set temperature 180°C 180°C 180°C 180°C Rotating speed 12RPM 12RPM 12RPM 12RPM Mold resin pressure 8.6MPa 16.1MPa 4.5MPa 5.1MPa Mold Mold 1 Mold 1 Mold 1 Mold 2 Physical Properties Foam Appearance Foam Density Foam Multiple Compression Strength Average Cell Diameter Cell Diameter Coefficient of Variation Thermal Conductivity ○ ○～△ × × ○ 41.5G/L 36.0G/L 112.5G/L 98.3G/L 11G/L 22 times 25 times 8 times 9 times 90 times 142kPa 133kPa undeterminable 166kPa Not determined 210μm 224μm 343μm 176μm 600μm 34 28 45 54 32 42mW/mK 42mW/mK undeterminable 44mW/mK 46mW/mK

Possibility of industrial use

The foam of the polyolefin-based resin composition of the present invention can be widely used in heat-insulating building materials, automobile parts, packaging cushioning materials, etc., due to its good balance between performance and cost and good recyclability.

In addition, all the contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2005-192375 filed on June 30, 2005 are incorporated herein as disclosure of the specification of the present invention.

Claims (8)

1. constructional heat-insulating foam board, it is characterized in that, use the whipping agent that comprises supercritical carbon dioxide at least, making the fusion tension force when comprising 230 ℃ is the polyolefin resin composition of the straight chain shape polypropylene-based resin of 5～30g, gets with the foaming of the foam expansion more than 10 times.

2. constructional heat-insulating foam board as claimed in claim 1 is characterized in that, the average bubble aperture and has abscess footpath distribution coefficient and directly distributes at the even abscess below 30% below 200 μ m.

3. constructional heat-insulating foam board as claimed in claim 1 or 2 is characterized in that, the fusion tension force in the time of 230 ℃ is that the content of straight chain shape polypropylene-based resin in aforementioned polyolefin resin composition of 5～30g is more than 50 quality %.

4. as each the described constructional heat-insulating foam board in the claim 1～3, it is characterized in that the thermal conductivity of measuring according to JIS-A1412 is 20～40mW/mK.

5. as each the described constructional heat-insulating foam board in the claim 1～4, it is characterized in that the thermal conductivity of measuring according to JIS-A1412 is 20～37mW/mK.

6. the manufacture method of constructional heat-insulating foam board, it is characterized in that, use has forcing machine and is installed on the foam device of the mould of front end, fusion tension force in the time of will comprising 230 ℃ is that the polyolefin resin composition of straight chain shape polypropylene-based resin of 5～30g and the whipping agent that comprises supercritical carbon dioxide at least melt extrude under 160～250 ℃ temperature condition, near the resin pressure mould openings portion is released under the atmosphere with 6～20MPa, carries out extrusion foaming.

7. the manufacture method of constructional heat-insulating foam board as claimed in claim 6 is characterized in that, near the resin pressure mould openings portion is released under the atmosphere with 7～15MPa, carries out extrusion foaming.

8. as the manufacture method of claim 6 or 7 described constructional heat-insulating foam boards, it is characterized in that forcing machine is that to extrude discharge-amount be 1～1000kg/ hour tandem type forcing machine.