JP2002144409A - Extruded foam sheet of polystyrene resin and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polystyrene resin foam sheet which has a sufficient expansion ratio for application to building material use and an outstanding dimensional stability even when the sheet is used at a high temperature or for a long time, in the extruded foam sheet which uses a 1,1,1,2-tetrafluoroethane and does not destroy an ozone layer. SOLUTION: This extruded foam sheet of a polystyrene resin is obtained by extruding a mixture of a mixed foaming agent containing the 1,1,1,2- tetrafluoroethane and a foamable molten resin containing the polystyrene resin from a high pressure region to a low pressure region and has a thickness of 20 nm or more and an apparent density of 25-40 kg/m3. In addition, the average cell diameter in the thickness direction of the surface layer part of the extruded foam sheet is 0.15-0.45 mm, and the residual amount of the 1,1,1,2- tetrafluoroethane in the extruded foam sheet is 0.3-0.75 g mol per 1 kg of polystyrene resin. Further, the thermal dimensional change of the extruded foam sheet to be sought when it is left alone for 7 days under conditions of the temperature of 70 deg.C and the relative humidity of 97% is -1.5 to 1.5% at the surface layer part and the center part in the thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruded foamed polystyrene resin foam heat insulating board used for heat insulating materials such as walls, floors and roofs of buildings and tatami mats, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, polystyrene resin foams have been
Because it has excellent heat insulating properties and suitable mechanical strength,
A plate formed into a plate having a certain width has been widely used as a heat insulating material. As a method for producing such a foamed board, there is known a production method in which a foam adjusting agent is added to a polystyrene-based resin material, heated and melt-kneaded, a physical foaming agent is added, and the mixture is extruded to a low pressure region.

[0003] As a foaming agent used in the production of the foamed board, chlorofluorohydrocarbons (hereinafter, referred to as CFC) such as dichlorodifluoromethane have been mainly used. Since CFC has excellent solubility in polystyrene resin, it is easy to manufacture a foamed board. In addition, the thermal conductivity in a gaseous state is lower than that of air and the permeation rate of polystyrene is much lower than that of air. The deterioration of the heat insulation performance with the passage of time of the body was small, and it was suitable as a foaming agent for producing a heat insulating material.

[0004] However, CFCs are extremely stable and difficult to decompose, and when discharged into the atmosphere, are decomposed by ultraviolet rays only after reaching the ozone layer surrounding the earth. Since it has been pointed out that chlorine atoms are generated when CFC is decomposed and the chlorine atoms may destroy the ozone layer, in recent years, hydrogen atom-containing chlorofluorocarbons (hereinafter, referred to as “hydrocarbon hydrocarbons”) in which chlorine atoms of CFC are partially hydrogenated. HCFC) is CFC
Has been used instead of

However, in terms of protection of the ozone layer, HCFCs containing chlorine atoms are still insufficient blowing agents, and fluorinated hydrocarbons containing no chlorine atoms in the molecule (hereinafter HF).
Called C. ) Is proposed, mainly using 1,
It is expected that 1,1,2-tetrafluoroethane will be used as a blowing agent.

[0006] 1,1,1,2-tetrafluoroethane has a low thermal conductivity in the gaseous state and has a very low permeation rate to polystyrene. Therefore, since the heat insulating property can be maintained for a long period of time, it has preferable characteristics as a foaming agent for producing a heat insulating material.

[0007]

The above-mentioned 1,1,1,2-
As a polystyrene resin foam plate using tetrafluoroethane, there is one disclosed in US Pat. US Pat.
01～0.3Mm, apparent density 12~96kg / m ³
It describes that a foamed board in which 1,1,1,2-tetrafluoroethane remains in an amount of 70% by weight or more in bubbles has excellent dimensional stability.

The present inventors have attempted to produce a polystyrene resin foam plate using 1,1,1,2-tetrafluoroethane based on these findings. However, 1,1,
Since 1,2-tetrafluoroethane has a low solubility in polystyrene, the addition of 1,1,1,2-tetrafluoroethane necessary to obtain a foamed board having the desired apparent density results in a decrease in pressure near the die lip. Due to the decrease, the foaming agent was separated, and it was difficult to obtain a foamed board having a low apparent density, that is, a high expansion ratio.

As a method for producing a polystyrene resin foam plate having a high expansion ratio, there is a method disclosed in Japanese Patent Publication No. 7-25123. According to the method disclosed in Japanese Patent Publication No. 7-25123, a molten resin mixture of a foaming agent or the like and a polystyrene-based resin is extruded and foamed from a die having a rectangular cross section, and at the same time, is kept warm or heated and both sides are open to the atmosphere. This is a method in which the surface of the extruded foam is passed through a molding device composed of parallel plates in contact, and then the extruded foam is passed through a heated or heated air atmosphere.

However, this method is disclosed in US Pat.
Even when applied to the foam obtained by the above method, a good product could not be obtained. That is, when the extruded foam plate is passed through a heated parallel plate forming apparatus in contact with the surface of the extruded foam and further passed through a heated atmosphere, the apparent density is slightly reduced, but the surface layer of the extruded foam plate is slightly reduced. Burning occurred in the part, the air bubbles were destroyed, and the cells became open cells, so that it was not possible to obtain the desired heat insulating property. The present inventors have studied the cause, and as a result, 1,1,1,2-tetrafluoroethane has a unique property of reducing the cell diameter of the obtained extruded foamed board, and the extruded foam having a small cell diameter is obtained. The plate was found to be due to reduced heat resistance as a result of the thinner bubble film.

As one of the methods for producing a polystyrene resin foam board using 1,1,1,2-tetrafluoroethane, hydrocarbons such as 1,1,1,2-tetrafluoroethane and butane are used. Japanese Patent Application Laid-Open No. 10-2920 discloses a method of using a mixture of water and an alkyl chloride such as methyl chloride as a foaming agent.
No. 63. JP-A-10-292063 describes that a foamed plate having an expansion ratio of 30 to 40 times can be manufactured by using the above foaming agent.

However, Japanese Unexamined Patent Publication No.
Is a method in which a foamable molten resin mixture of a foaming agent or the like and a polystyrene-based resin is directly discharged into the atmosphere from a die having a rectangular cross section, so that the foam plate manufactured by the method has a surface layer portion. And the difference in heating dimensional change and apparent density difference in the central part in the thickness direction were large, and the dimensional stability at high temperatures was poor.

That is, when the foamable molten resin mixture is discharged directly from the die into the atmosphere, the surface layer of the extruded foam plate is cooled rapidly, so that foaming is suppressed and the apparent density becomes relatively high. While stress is generated, the inside of the extruded foam plate in the thickness direction is gradually cooled by the heat insulating effect of the foam, so that the apparent density becomes relatively low, and no residual stress is generated. As a result, foams quenched at the time of foaming have residual stress in the surface layer and a large difference in apparent density between the surface layer and the inside of the thickness direction, resulting in lack of dimensional stability when used at high temperatures. Becomes

When such a foamed board having poor dimensional stability is used as a wall material, a roofing material, or the like, expansion, shrinkage, distortion, or the like occurs after construction depending on the use condition, and therefore, it is difficult to use it for practical use. Not preferred.

[0015] In view of the above-mentioned drawbacks of the extruded foam board, the present invention provides an extruded foam board using 1,1,1,2-tetrafluoroethane as a foaming agent which does not destroy the ozone layer. An object of the present invention is to provide a polystyrene-based resin foam board having a sufficient expansion ratio to be used, and excellent in dimensional stability even when used at high temperatures or when used for a long time.

[0016]

SUMMARY OF THE INVENTION The present invention provides (1) 1,
Thickness 20 obtained by extruding a foaming molten resin mixture containing a mixed foaming agent containing 1,1,2-tetrafluoroethane and a polystyrene-based resin from a high pressure range to a low pressure range.
extruded polystyrene resin foam plate having an apparent density of 25 to 40 kg / m ³ or more, wherein the average cell diameter in the thickness direction of the surface layer portion of the extruded foam plate is 0.15 to 0.45 mm; The residual amount of 1,1,1,2-tetrafluoroethane in the plate was 0.3 kg / kg of polystyrene resin.
０．７0.75 mol, and the change in the heating dimension required by leaving it to stand for 7 days at a temperature of 70 ° C. and a relative humidity of 97% was −1. extruded polystyrene resin foam plate, which is a 5 to 1.5%, (2) the extruded foam plate surface layer portion of the thickness direction average cell diameter L ₁ and the extruded foam board in the thickness direction central portion of the The ratio (L ₁ / L ₂ ) to the average cell diameter L _{2 in the} thickness direction is 0.7 to 1.0, and the apparent density D ₁ of the surface layer portion of the extruded foam plate and the center in the thickness direction of the extruded foam plate parts ratio of the apparent density D ₂ of (D ₁ / D ₂₎ is 0.9
(1) an extruded polystyrene resin foam plate according to (1), (3) a mixed foaming agent containing 30 to 55 mol% of 1,1,1,2-tetrafluoroethane and a polystyrene resin A foamable molten resin mixture containing a resin,
After extruding from the tip of the extruder and passing it through a heating mold attached to the tip of the extruder to form a plate-like foam, the plate-like foam is introduced into a heating device to be heated and expanded. (4) The method for producing an extruded polystyrene resin foam board according to the above (1), (4) the average cell diameter in the thickness direction of the surface layer portion of the plate-like foam is 0.1 mm or more. (5) The extruded polystyrene resin foam according to (3) or (4), wherein (5) the plate-like foam is heated and expanded by steam in a heating device. (6) The heating device is temperature-controlled to "the Vicat softening temperature of the polystyrene resin -15 ° C" to "the Vicat softening temperature of the polystyrene resin + 30 ° C", and the heating device Wherein the temperature of the polystyrene resin is controlled to "the Vicat softening temperature of the polystyrene resin -15 ° C" to "the Vicat softening temperature of the polystyrene resin + 10 ° C". (7) The method for producing an extruded polystyrene resin foam board according to (7), wherein the mixed foaming agent is 1,1,1,2-tetrafluoroethane 3
0 to 55 mol%, isobutane and / or normal butane 0 to 30 mol%, and methyl chloride and / or ethyl chloride 15 to 70 mol% (the total amount of these blowing agents is 100 mol%. The gist of the present invention is a method for producing an extruded polystyrene resin foam board according to any one of the above (3) to (6).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An extruded polystyrene resin foam board (hereinafter referred to as an extruded foam board) of the present invention comprises a polystyrene resin and 1,1,1,2-tetrafluoroethane (hereinafter referred to as HFC134a). It has a high thickness, a low apparent density, and is excellent in dimensional stability, obtained by an extrusion foaming method using an extruder using a mixed foaming agent.

Examples of the polystyrene resin used in the present invention include styrene homopolymer, styrene-acrylic acid copolymer containing styrene as a main component, styrene-methacrylic acid copolymer, and styrene-maleic anhydride copolymer. , Styrene-butadiene copolymer, styrene-
Acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, high impact polystyrene and the like can be mentioned. The content of the styrene component in the styrene copolymer is preferably 50 mol% or more, and particularly preferably 80 mol% or more.

The polystyrene resin used in the present invention has a melt flow rate (MFR) of 0.5 to 30 g / g.
It is preferable to use one having a range of 10 minutes (however, the MFR measured according to ASTM D1238-73 Condition G). , And the obtained extruded foam board is excellent in mechanical strength.

In the present invention, a mixed foaming agent containing HFC134a is used. Since HFC134a is a physical foaming agent having an ozone depletion potential of 0, the foam of the present invention does not destroy the ozone layer. HFC134a
Has a low thermal conductivity in a gaseous state, so that the heat insulating property is maintained for a long time.

However, HFC134a has inferior compatibility and uniform dispersibility with polystyrene resins as compared with CFC and HCFC used so far. Therefore, if only HFC134a is used as a foaming agent, a foamed board having a low apparent density, which is the object of the present invention, cannot be obtained. The same can be said for the case where a mixed foaming agent containing 70% by weight or more of HFC134a is used.
Therefore, in the production method of the present invention, a mixed foaming agent containing 30 to 55 mol% of HFC134a and another foaming agent is used. The residual amount of HFC134a in the foamed board obtained by using the mixed foaming agent having such a composition can be 0.3 to 0.75 mol per kg of the polystyrene resin.

When the HFC134a in the mixed foaming agent is less than 30 mol%, an extruded foam plate having sufficient heat insulating properties cannot be obtained, and when it exceeds 55 mol%, the cell diameter of the extruded foam plate becomes too small. Therefore, it becomes difficult to obtain an extruded foam plate having a low apparent density and excellent dimensional stability.

Other foaming agents to be mixed include aliphatic hydrocarbons such as 1,1-difluoroethane, propane, normal butane, isobutane, normal pentane, isopentane and neopentane, and methyl chloride and ethyl chloride. Chlorinated hydrocarbons, various alcohols,
A blowing agent having an ozone destruction coefficient of 0 such as carbon dioxide may be mentioned, and any one of these blowing agents may be mixed,
Alternatively, two or more kinds may be used as a mixture.

A preferred mixed blowing agent for achieving the intended object of the present invention is 30 to 55 mol% of HFC134a,
Isobutane and / or normal butane 0 to 30 mol%
And methyl chloride and / or ethyl chloride 15 to 70 mol%
(However, the total amount of these blowing agents is 100 mol%).

When the isobutane and / or normal butane in the mixed foaming agent exceeds 30 mol%, these foaming agents have high flammability and the flame retardancy of the foamed board is deteriorated. There is a possibility that it cannot be used for the intended use. If the amount of methyl chloride and / or ethyl chloride in the mixed foaming agent is less than 15 mol%, it may be difficult to obtain an extruded foam board having a low apparent density that can achieve the intended purpose. On the other hand, when the content of methyl chloride and / or ethyl chloride exceeds 70 mol%, the heat insulating property decreases.

In addition, as long as the intended purpose of the present invention is not impaired, in addition to the mixed blowing agent satisfying the above conditions, other blowing agents (preferably 10 parts by weight per 100 parts by weight of the mixed blowing agent). (In the range of not more than 3 parts by weight) may be kneaded with the polystyrene resin to form a foamable molten resin mixture.

However, the extruded foamed board obtained by using the above-mentioned mixed foaming agent is not sufficient in dimensional stability, particularly in dimensional stability under high temperature conditions. The reason is,
Even if the extruded foam board is manufactured simply as in the prior art, the strain generated during the production of the foam board, that is, the dimensional stability is considered to be poor unless the residual stress of the extruded foam board is eliminated.
The cause of the poor dimensional stability of the extruded foam board is HFC13
4a has a characteristic of reducing the cell diameter of the obtained foamed board as compared with conventional chlorofluorohydrocarbons such as CFC and HCFC. It is considered that the strength of the constituent bubbles is insufficient.

This opinion is different from the conventional one, and has been reached as a result of intensive studies by the present inventors. That is,
Conventionally, a foam plate having small air bubbles has been considered preferable because it is excellent in terms of heat insulation. However, according to a study by the present inventors, in an extruded foam plate having a specific apparent density obtained by using a mixed foaming agent containing HFC134a, one having a too small cell diameter has insufficient cell strength and heat resistance. Therefore, it is considered that the extruded foam plate cannot sufficiently withstand the residual stress, and as a result, a large dimensional change is caused.

The present invention has been made based on the above observation. The extruded foam board provided by the present invention has an apparent density of 25 to 40 kg / m ³ obtained using the above-mentioned mixed foaming agent.
The average cell diameter in the thickness direction of the surface layer of the extruded foam plate is 0.15 to 0.45 mm.

Hereinafter, a production example of the extruded foam board of the present invention will be described in detail. The extruded foam plate is made of a polystyrene resin and H
A mixed foaming agent containing 30 to 55 mol% of FC134a,
After heating, melting and kneading using an extruder to form a foamable molten resin mixture, the foamable molten resin mixture is extruded from a die lip, and further passed through a heating molding tool attached to the extruder tip to form a plate. After forming a foam, the plate-like foam can be heated and expanded in a heating device to obtain an extruded foam plate.

The polystyrene resin used for producing the extruded foam board of the present invention is as described above. In the method of the present invention, as described above, HFC134a is
A mixed foaming agent containing 5 mol% is used. When such a mixed foaming agent is used, the residual amount of the HFC134a is 0.3 to 0.75 mol per 1 kg of the polystyrene resin, and an extruded foam plate having good heat insulating properties can be obtained.

The amount of the mixed foaming agent is appropriately added to the base resin in accordance with the desired apparent density of the extruded foamed board. However, from the viewpoint of the production stability of the extruded foamed board, polystyrene resin is used. It is preferable to use 0.9 to 1.5 mol per 1 kg. As described above, HFC134a in the mixed foaming agent is preferably used in a ratio of 0.3 to 0.75 mol per 1 kg of the polystyrene resin. HFC134 per 1 kg of polystyrene resin
When the use ratio of a is less than 0.3 mol, there is a possibility that the heat insulating property required for the extruded foam board for building materials may not be obtained. On the other hand, when it exceeds 0.75 mol, the cell diameter of the obtained extruded foamed board becomes too small, and there is a possibility that molding with a heat molding tool becomes difficult, and an apparent density of 25 to 40 kg.
/ M ³ There is a possibility that an extruded foam plate excellent in appearance and heat insulating property cannot be obtained.

In the present invention, for example, a foam control agent is added to the base resin as an additive. The cell regulator is an additive for adjusting the average cell diameter of the extruded foam board. Examples of the foam regulator include inorganic powders such as talc, kaolin, mica, silica, calcium carbonate, barium sulfate, titanium oxide, clay, aluminum oxide, bentonite, diatomaceous earth, sodium bicarbonate, and monosodium citrate. However, talc is preferred because it is easy to adjust the bubble diameter and inexpensive. Further, in the present invention, two or more types of the bubble regulator can be used in combination. The amount of the cell regulator is 0.1 to 2 parts by weight, preferably 0.2 to 1 part by weight, based on 100 parts by weight of the polystyrene resin.

The average cell diameter of the extruded foam plate, particularly the average cell diameter in the thickness direction of the surface layer of the extruded foam plate, is determined by the amount of the polystyrene resin as the base resin in addition to the type and amount of the cell regulator. The viscoelasticity, the type and amount of the mixed foaming agent and the amount added, vary depending on factors such as the characteristics of the extruder. Important to get.

To the extruded foam board of the present invention, various additives such as the above-mentioned cell regulator, flame retardant, and colorant are appropriately selected and added.

FIG. 1 shows an example of an apparatus used in the manufacturing method of the present invention. In FIG. 1, 1 is a die lip,
2 is a foamed molten resin mixture, 3 is a heat molding tool, 4 is a heating device, 5 is a plate-like foam, 6 is an extruded foam plate, 7
Denotes a steam supply pipe, and 8 denotes a steam exhaust pipe.

The foamable molten resin mixture 2 extruded from the die lip 1 fills the heating molding tool 3 while passing through the heating molding tool 3 to form a plate-like foam 5.
Next, while the plate-like foam 5 passes through the heating device 4 provided continuously to the heat molding tool 3, the “base resin resin Vicat softening temperature −15 ° C.” to “the base resin vicat softening” Temperature +
10 [deg.] C. "until the foaming is almost completely completed and the extruded foam plate 6 is obtained.
Since the temperature is maintained at 15 ° C. or higher, a large residual stress does not occur in the obtained extruded foam board.

Therefore, according to the method of the present invention, an extruded foam plate 6 having a low apparent density can be efficiently obtained. Further, since the plate-like foam 5 is heated and expanded into the extruded foam plate 6 in the heating device 4, the amount of the foaming agent necessary for obtaining a product having the desired apparent density is small. as a result,
Since the amount of HFC134a used is small, it is easy to adjust the bubble diameter so as not to be small.

However, if the plate-like foam 5 is heated in the heating device 4 in order to obtain an extruded foam plate with a low apparent density, the amount of HFC134a used can be reduced.
As long as FC134a is used, there is no change in the tendency that the cell diameter of the plate-like foam becomes smaller as described above. Therefore, if the bubble diameter of the plate-like foam 5 is too small, the bubble film in the surface layer is too thin to withstand heating in the heating device 4, and the bubbles in the surface layer break to form bubbles. It becomes a foam, the appearance deteriorates, and does not have the heat insulation required for building materials.

As a means for reliably avoiding such inconveniences, the cell diameter in the thickness direction of the surface layer of the plate-like foam 5 is set to 0.1%.
mm or more, in particular, in the range of 0.1 mm to 0.3 mm. Does not break.

Next, the specific adjustment of the cell diameter in the thickness direction of the surface layer portion of the plate-like foam in the heat forming tool 3 will be described. Adjustment of the cell diameter in the thickness direction of the surface layer portion of the plate-like foam 5 can be performed by adjusting the temperature of the heat molding tool 3 or adjusting the speed ratio between the extrusion speed and the take-up speed of the foamable molten resin mixture. This is because, when the temperature of the heat molding tool 3 is high, foaming tends to be promoted and becomes large, and when the temperature of the heat molding tool 3 is low, foaming tends to be suppressed and becomes small. This is because when the take-up speed is made slower than the take-up speed and the resin mixture is filled in the heat molding tool, if the take-up speed is too slow, the bubble diameter becomes smaller.

Specifically, the bubble diameter in the thickness direction is 0.1 m
In order to be within the range of m to 0.3 mm, the heat-molding tool 3 needs to be “Vicat softening temperature of base resin −15 ° C.”
It is preferable that the temperature is adjusted to “Vicat softening temperature of base resin + 30 ° C.”, and “Vicat softening temperature of base resin−15 ° C.” to (Vicat softening temperature of base resin + 20)
More preferably, the temperature is adjusted to “° C.”. By adjusting the temperature of the heat forming tool 3 to the above-described temperature, the effect of eliminating the apparent density difference between the surface layer portion of the plate-like foam 5 and the inside in the thickness direction and the appearance of the plate-like foam 5 in addition to the above-described bubble diameter adjusting effect. It has the effect of improving. If the temperature of the heat forming tool 3 is too low, the cell diameter in the thickness direction of the surface layer of the plate-like foam 5 becomes small, while if the temperature of the heat forming tool 3 is too high, the surface of the obtained plate-like foam 5 is obtained. As a result, surface irregularities (hereinafter, referred to as flow marks) are generated, which causes a deterioration in appearance.
In this specification, the temperature of the heat forming tool refers to the temperature of the central portion of the parallel plate of the heat forming tool 3 as indicated by symbol A in FIG.

When the plate-like foam 5 is adjusted in the cell diameter or the like as described above, even if it is heated while passing through the inside of the heating device 4, the surface layer of the extruded foam plate 6 is burnt or has an open cell. Never do. Furthermore, when the foamable molten resin mixture 2 extruded from the die lip 1 is heated and kept in the heating molding tool 3 and the heating device 4 at a temperature equal to or higher than “the Vicat softening temperature of the base resin −15 ° C.”, a dimensional change is caused. Since the difference in apparent density between the surface layer and the inside and the residual stress applied to the foamed board during molding can be removed, an extruded foamed board 6 having little dimensional change and excellent dimensional stability can be obtained.

The ratio of the average cell diameter of the surface layer to the average cell diameter at the center in the thickness direction of the plate-like foam (the average cell diameter at the surface layer / the average cell diameter at the center in the thickness direction) of the plate-like foam 5 Diameter)
Is preferably from 0.5 to 0.8, since excellent heat expansion properties can be exhibited when heated by a heating device in a later step.

The heat forming tool 3 and the heating device 4 are continuously connected or, as shown in FIG. 1, the temperature of the surface of the plate-like foam 5 is not lower than “the Vicat softening temperature of the base resin−15 ° C.”. It is preferable to set the section between them as short as possible. Otherwise, the plate-like foam 5 is cooled in the section between the heating molding tool 3 and the heating device 4, so that not only energy loss occurs but also the heating in the heating device 4 The effect of improving magnification and the effect of removing residual stress may not be sufficiently obtained.

The term "Vicat softening temperature" as used herein means the JIS K7206 (1999) A50 of a polystyrene resin constituting a plate-like foam or an extruded foam plate.
Is the Vicat softening temperature determined by the method.

The heating in the heating device 4 is preferably performed using steam. Since the steam has a large amount of heat and excellent permeability to the polystyrene resin, the heat and expansion of the plate-like foam 5 efficiently in a short time, the uniformity of the apparent density difference between the surface layer portion and the inside of the thickness direction is improved. The residual stress of the plate-like foam can be removed. Therefore, when steam is used, the length in the heating device 4 can be shortened. Furthermore, it is easy to make the temperature in the heating device 4 uniform and to uniformly heat the plate-like foam 5 to the inside, so that the appearance and heat insulation due to foam breaking on the surface of the extruded foam plate 6 due to excessive heating. (Hereinafter referred to as burning) is less likely to occur.

However, an electric heater or heated air can be used as a heating source in the heating device 4. Use of an electric heater or heated air is convenient because the temperature in the heating device 4 can be arbitrarily set. However, it is difficult to uniformly heat the inside of the plate-like foam 5 and if the heating conditions are set so that the foam on the surface of the plate-like foam 5 does not occur, the amount of heat given to the plate-like foam 5 must be reduced. Therefore, in order to make the apparent density difference uniform while removing and expanding the residual stress in the surface layer while heating and expanding the plate-like foam 5, it is necessary to lengthen the inside of the heating device 4 as compared with the case where steam is used. .

In the heating device 4, while the plate-like foam 5 is sufficiently heated and expanded, the apparent density of the surface layer portion and the inside in the thickness direction is made uniform, and residual stress is removed. Is obtained, the “Vicat softening temperature of the base resin—15 ° C.” to the “Vicat softening temperature of the base resin +
It is preferred that the temperature be adjusted to 10 ° C. If the temperature in the heating device is too low, the above effect cannot be obtained, and if the temperature is too high, burning occurs on the surface of the extruded foam plate 6. In this specification, the temperature in the heating device refers to the temperature at the center of the heating device 4 as indicated by the symbol B in FIG.

According to the method described above, HFC134
By using a, it is possible to obtain an extruded foam plate having a low apparent density, a small distortion in the surface layer during foaming, and excellent dimensional stability and excellent heat insulation. However, the extruded foam board of the present invention can be obtained by the above method, but is not limited to the method. For example, those having a sufficient thickness without actively filling the foaming molten resin mixture in the heating molding tool to minimize the generation of residual stress due to strain during extrusion foaming without using a heating device There is a method using a large-sized extruder capable of producing the same. By using such a large extruder, the type and amount of the cell regulator are adjusted, and by a method such as extrusion foaming to a reduced pressure region below atmospheric pressure, the apparent density, thickness, and thickness specified by the present invention are also specified. By manufacturing a product that satisfies the conditions of the average cell diameter and the remaining amount of HFC134a, it is possible to obtain the extruded foam plate of the present invention that satisfies the intended purpose.

The extruded foam board of the present invention has a thickness of 20 mm or more and an apparent density of 25 to 40 kg / m ³ . When the thickness is less than 20 mm, a device such as lamination is required to secure sufficient heat insulating properties, and a problem in productivity remains. In addition, there is also a balance with the apparent density, but those of the apparent density that can achieve sufficient heat insulating properties and light weight of the object of the present invention, and those having a small thickness are insufficient in mechanical strength such as bending. Therefore, there is a problem that workability and the like are deteriorated. When the apparent density of the extruded foam board is less than 25 kg / m ³ , it is quite difficult to produce an extruded foam having such an apparent density, but the mechanical properties of the obtained extruded foam board are difficult. The physical properties are also inadequate as compared with the conventional foam insulation board, and the usable applications are limited. On the other hand, apparent density is 40kg
If the thickness exceeds / m ³ , it is difficult to exhibit sufficient heat insulating properties unless the thickness is increased more than necessary, and the weight is insufficient in terms of lightness.

The change in the heating dimension of the surface layer portion of the extruded foam board of the present invention and the change in the heating dimension of the central part in the thickness direction of the foam board were -1. 5 to 1.5%. Extruded foam board of the present invention,
Since the absolute value of the heating dimensional change at a high temperature of 70 ° C. is a small value of 1.5% or less, excellent dimensional stability is exhibited even when used at a high temperature. The heating dimensional change of the extruded foam board of the present invention under the above-mentioned conditions is caused by all of the extrusion direction, width direction, and thickness direction in the surface layer portion (the upper surface layer portion and the lower surface layer portion) and the center portion in the thickness direction. It means that the heating dimensional change is in the range of -1.5 to 1.5%. What shows such a heating dimensional change means that no residual stress due to cooling at the time of foaming is generated in the surface layer portion of the extruded foamed board, and the extruded foamed board has dimensional stability at high temperatures and for a long period of time. It also means that it is extremely excellent.

In the extruded foam plate, the dimensional change under heating at any part under the above conditions is less than -1.5%.
If it exceeds 5%, the dimensional change due to heating is too large, and dimensional stability at high temperatures such as wall materials, flooring materials, and roofing materials, and dimensional stability in long-term use such as tatami core materials are required. It is not preferable to use it as an extruded foam plate in the field to be used. Further, a sample having a length of 20 cm, a width of 20 cm, and a thickness of the extruded foam plate is cut out from the extruded foam, and the heating dimensional change of the entire extruded foam plate obtained under the above conditions is -1.5 to 1.
Even if it is 5%, the heating dimensional change in either the surface layer portion or the center portion in the thickness direction of the extruded foam board is -1.5 to 1.5.
% Is not satisfied, it is difficult to say that the dimensional stability when an extruded foam board is actually used is sufficient.
When used as a wall material, a floor material, a roof material, a core material of a tatami mat, or the like, expansion, shrinkage, distortion, or the like after construction may occur.

In the present specification, the change in heating dimension is AST
Leave in an oven at a temperature of 70 ° C. and a relative humidity of 97% for 7 days in accordance with MD2126-75 / ASTMC578-87a, measure the dimensional change before and after the leaving in the extrusion direction, width direction and thickness direction, and calculate by the following formula. It shall be.

[0055]

## EQU1 ## Dimensional change in heating (%) = (length of test piece after standing by heating / length of test piece before standing by heating) × 100

The adjustment of the test piece for determining the change in the heating dimension of the surface layer portion or the central portion in the thickness direction of the extruded foam plate is as follows. In the surface layer of the extruded foam plate, a portion within a range of 6 mm in the thickness direction from the upper surface and the lower surface of the extruded foam plate is horizontally sliced, and the sliced sample is vertically cut by 20 mm.
cm, 20 cm in width and 6 mm in thickness are obtained. At the center in the thickness direction of the extruded foam plate, a portion within a range of a total thickness of 6 mm, that is, a thickness of 3 mm above a center plane that divides the thickness of the extruded foam plate into two and a thickness of 3 mm below the center plane, is horizontally. Sliced, 20c vertically from the sliced sample
A test piece of m, 20 cm in width and 6 mm in thickness is obtained.

The average cell diameter in the thickness direction of the surface layer of the extruded foam plate of the present invention (the surface layer on the upper surface portion and the surface layer portion on the lower surface of the extruded foam plate) is 0.15 to 0.45 m.
m. When the average bubble diameter is less than 0.15 mm,
When used as an architectural material because the cell diameter of the surface layer is too small and the cell membrane is too thin, there is a risk that the appearance of the surface layer will deteriorate or dimensional changes will easily occur. On the other hand, if the average cell diameter exceeds 0.45 mm, there is a possibility that the heat insulation required for building materials may not be obtained.

The average cell diameter in the thickness direction of the central part in the thickness direction of the extruded foamed plate of the present invention is preferably 0.18 to 0.50 mm from the viewpoint that the heat resistance and the heat insulation are particularly excellent. .

In the extruded foam board of the present invention, HFC1
The remaining amount of 34a is 0.3 kg / kg of polystyrene resin.
０．７0.75 mol, preferably 0.35 to 0.6 mol. When the residual amount is less than 0.3 mol per 1 kg of the polystyrene resin, there is a possibility that the heat insulating property required for a heat insulating material for building use cannot be obtained for a long time. on the other hand,
When it exceeds 0.75 mol, as described above, HFC1
34a has the property of reducing the cell diameter during foaming, so that the average cell diameter in the thickness direction of the surface layer is 0.15 mm.
The extruded foam plate may be less than 100%, resulting in insufficient appearance and dimensional stability.

In the present specification, the remaining amount of HFC134a is determined by using a gas chromatograph. In particular,
Put the sample cut out from the center of the extruded foam plate into a sample bottle with a lid containing toluene, close the lid,
After sufficient stirring, the HFC134a in the extruded foam plate is dissolved in toluene to prepare a measurement sample, and the sample is subjected to gas chromatography analysis to determine the remaining amount of HFC134a contained in the foam plate.

The measurement conditions for gas chromatography analysis are as follows. Column: Silicone DC, manufactured by Shinwa Kako Co., Ltd.
550 20%, column length 4.1 m, column inner diameter 3.
2mm, support: Chromosorb AW-DM
CS, mesh 60-80 Column temperature: 40 ° C. Inlet temperature: 200 ° C. Carrier gas: nitrogen Carrier gas speed: 3.5 ml / min Detector: FID Detector temperature: 200 ° C. Quantification: Internal standard method

In the present invention, the ratio (L ₁ / L ₂ ) of the average cell diameter L _{1 at} the surface layer of the extruded foam plate to the average cell diameter L ₂ at the center in the thickness direction of the extruded foam plate is 0.7 to 0.75. 1.0, and more preferably 0.85 to 1.0, is particularly preferable because it has excellent dimensional stability and heat insulation.

The average cell diameter L ₁ is measured at each of the upper surface layer and the lower surface layer of the extruded foam plate. Therefore, the relationship of (L ₁ / L ₂ ) is based on the average cell diameter L _1-1 of the upper surface layer and the average cell diameter L of the lower surface layer.
_In each of _1-2 , (L _1-1 / L ₂ ) is 0.7 to 1.0,
It means that (L _1-2 / L ₂ ) preferably satisfies the relationship of 0.7 to 1.0.

The average cell diameter L ₁ (mm) in the present specification
Is as follows. The cross section perpendicular to the width direction of the extruded foam plate is enlarged with a microscope or the like to obtain an enlarged sectional view. In the obtained cross-sectional view, a line segment having a length corresponding to a length before expansion of 6 mm is drawn from the upper surface of the extruded foam plate in the thickness direction. Next, the number n of the bubbles intersecting with the line segment (where n includes the one where some of the bubbles intersect the line segment) is obtained, and the number is calculated on the line segment by the formula: (6 / n). Calculate the average bubble diameter of the bubbles.

[0065] The measurement of the average cell diameter L _1-1 of the surface layer portion of the upper surface, the central portion in the width direction of the extruded foam plate measurement of the average cell diameter of 6mm portion from the upper surface of the extruded foam board and The calculation is performed near both ends, and the arithmetic average value of the average bubble diameters of the bubbles on the obtained line segments is defined as an average bubble diameter _L1-1 . Also,
The measurement of the average cell diameter L _1-2 of the surface layer portion on the lower surface side is carried out in the thickness direction from the lower surface of the extruded foam plate, for a portion having a length corresponding to a length of 6 mm before enlargement, similarly. The obtained value is defined as the average bubble diameter L _1-2 .

Further, in the present specification, the average bubble diameter L
_TwoThe measuring method of (mm) is as follows. Extruded foam board
Enlarge the cross section perpendicular to the width direction with a microscope etc.
obtain. In the obtained sectional view, the thickness direction of the extruded foam board
At the intersection with the center line that bisects the thickness of the foam board
As a line segment whose length before enlargement is equivalent to 6 mm
(3 mm above the intersection and 3 mm below the intersection, for a total of 6
A line segment having a length corresponding to mm) is drawn. Then cross the line
The number of air bubbles n (where n is a part of air bubbles
Includes what is inserted. ), And the calculation formula is (6 / n).
Calculate the average bubble diameter of the bubbles on the line segment. In addition, the above operation
Lines near the center and both ends in the width direction of the extruded foam board
Arithmetic mean of the average bubble diameter of bubbles on each obtained line segment
The value is the average bubble diameter L _TwoAnd

[0067] In the present invention, the ratio of the apparent density D ₂ in the thickness direction central portion of the apparent density D ₁ and the foamed plate of the surface layer portion of the extruded foam board (D ₁ / D ₂₎ is from 0.9 to 1.1 It is preferred that When the ratio (D ₁ / D ₂ ) is within the above range, further improvement in heat insulation and dimensional stability can be expected.
Incidentally, the apparent density D ₁ of the surface layer portion was measured at the surface layer portion on the upper surface side and the surface layer portion on the lower surface side of the extruded foamed board, and the above (D ₁
/ D ₂ ), the apparent density D _1-1 of the surface layer on the upper surface side and the apparent density D _1-2 of the surface layer on the lower surface side are (D D).
_1-1 / D ₂₎ is 0.9 to 1.1, the (D _1-2 / D ₂₎ 0.9
It means that it is preferable to satisfy the relationship of ~ 1.1.

The apparent density D ₁ of the surface layer in the present specification
(Kg / m ³ ) is determined as follows. A portion within a range of 6 mm in the thickness direction from the upper surface of the extruded foam board is horizontally sliced, and the sliced sample is vertically cut by 20 c.
A test piece of m, 20 cm in width and 6 mm in thickness is obtained. The weight (g) of the obtained test piece is measured, divided by the volume (cm ³ ) obtained from the outer dimensions of the test piece, and converted to a unit of kg / m ³ . The above operation is also performed on a portion within a range of 6 mm in the thickness direction from the lower surface of the extruded foam plate. Then, the obtained apparent densities are calculated as the apparent density D _{1-1 of} the upper surface layer portion and the apparent density D _{1-2 of the} lower surface layer portion.
And

The apparent density D ₂ (kg / m ³ ) at the center in the thickness direction in this specification is obtained as follows. 3m thick above the center plane which divides the thickness of the extruded foam board into two equal parts
m, a portion within a range of a total thickness of 6 mm of 3 mm below the center plane is horizontally sliced, and a test piece having a length of 20 cm, a width of 20 cm and a thickness of 6 mm is obtained from the sliced sample. The weight (g) of the obtained test piece was measured and divided by the volume (cm ³ ) obtained from the outer dimensions of the test piece,
The value obtained by converting the unit to kg / m ³ is defined as the apparent density D _{2 at the} center in the thickness direction. Further, the apparent density of the extruded foam board in the present specification is JIS K7222.
(1985).

[0070]

Next, the present invention will be described in more detail with reference to specific examples. Example 1 As raw materials, 100 parts of polystyrene resin "HH32" (Vikato softening temperature: 101 ° C) manufactured by Idemitsu Petrochemical Co., Ltd., 0.5 part of talc as a cell regulator, and hexabromocyclo as a flame retardant were used. A mixture of dodecane and a stabilizer in an amount of 2 parts and a mixed foaming agent having the composition shown in Table 1 were used.

The extruder is an extruder having a diameter of 65 mm (hereinafter referred to as an extruder).
It is called "first extruder". ) And an extruder having a diameter of 90 mm (hereinafter, referred to as “second extruder”) and an extruder having a diameter of 150 mm (hereinafter, referred to as “third extruder”) are connected in series. The agent was pressed and kneaded into the molten resin near the tip of the first extruder.

The die lip has a resin outlet at the end with a width of 100 mm and a gap of 1.5 mm (rectangular cross section).
The inlet dimensions are slightly larger than the resin outlet, and the outlet dimensions are 40 mm thick and 300 mm wide. As shown in Fig. 1, it consists of an inclined plate that gradually expands from near the inlet to the outlet, and a parallel plate thereafter. Fluororesins whose both sides were open to the atmosphere were used.

As shown in FIG. 1, the heating device having a length of 1750 mm and having a structure for injecting steam toward the internal plate-like foam passage was provided at the outlet of the heating molding tool as shown in FIG.

Using the above apparatus, a raw material such as a polystyrene resin is supplied to the first extruder, heated to 220 ° C., melt-kneaded, and then the resin temperature is adjusted by the second and third extruders. The resin pressure at the attached adapter is 40
After adjusting to kgf / cm ² , the mixture was extruded from a die lip. The molten resin mixture extruded from the die lip was filled in a heating mold heated to 100 ° C. while being foamed, so as to be formed into a rectangular cross-section having a thickness of 40 mm and a width of 340 mm, and a plate-shaped foam shown in Table 2 was obtained. The obtained foam was further heated by steam in a continuous heating device to form an extruded foam plate shown in Table 3.

Table 1 shows the mixing amount of each foaming agent, the temperature of the heat forming tool, and the temperature of the temperature in the heating device. The apparent density of the obtained extruded foamed board, the cell diameter in the thickness direction at the surface layer and the center in the thickness direction, are shown in Table 1. The apparent density of the upper and lower surface layers and the central part in the thickness direction, the temperature of 70 ° C., the relative humidity of 97%, the entire extruded foam plate under the conditions of 7 days, the change in the heating dimensions of the upper and lower surface parts and the central part in the thickness direction, heat conduction Table 3 shows the rates and the like. In Examples and Comparative Examples, the temperature of the heat forming tool was measured using a thermocouple at the center of the parallel plate (A in FIG. 1), and the temperature in the heating device was measured at the center of the heating device (B in FIG. 1). Measured.

[0076]

[Table 1] The values in parentheses in Table 1 represent mol%.

[0077]

[Table 2]

[0078]

[Table 3]

The measurement of the heating dimensional change in Table 3 was performed according to ASTM.
According to D2126-75 / ASTM C578-87a, an extruded foam plate obtained as a test piece was cut into a 200 mm square, and the upper and lower surface portions were further cut out by 6 mm.
And a slice of 6 mm thickness centered on the center in the thickness direction are allowed to stand in an oven at a temperature of 70 ° C. and a relative humidity of 97% for 7 days, and the dimensions before and after leaving are measured. It was done by doing.

The "warpage" in the column of the heating dimensional change in Table 3 was measured as follows. First, the test piece 11 after the above-mentioned heating measurement was placed on a flat table so that the upper part became convex as shown in FIG. Next, the upper surface 12 of the flat table and the test piece 11
Was measured with respect to the lower surface 13, and the distance h (mm) was defined as “sledge”.

The evaluation of the surface condition in Table 3 was evaluated as ○ when the extruded foam plate had a smooth surface and good appearance, and x when the extruded foam plate had a flow mark or burn on the surface.

The remaining amount of HFC134a in Table 3 was measured by Shimadzu Gas Chromatograph GC-14 manufactured by Shimadzu Corporation.
B was measured according to the above method using cyclopentane as an internal standard.

In the measurement of the thermal conductivity in Table 3, a test piece having a length of 20 cm, a width of 20 cm, and a thickness: extruded foam plate was cut out from the extruded foam plate, and a test piece 1 of the direct plate method was prepared according to JIS A1412 (1994). It was measured by the sheet method.

Example 2 The size of the resin outlet of the die lip was 115 mm in width and the gap 1
mm (rectangular cross section), the outlet dimensions of the heat molding tool were 25 mm in thickness and 260 mm in width, and the cross section of the obtained extruded foam plate was a rectangle having a thickness of 25 mm and a width of 270 mm. Similarly, an extruded foam board was formed.

Comparative Example 1 Except that steam heating in the heating device was not performed,
An extruded foam board was formed in the same manner as in Example 1.

Comparative Example 2 An extruded foam plate was formed in the same manner as in Example 1 except that the heating in the heating molding tool and the steam heating in the heating device were not performed.

Comparative Example 3 An extruded foam plate was formed in the same manner as in Example 1 except that one part of talc as a cell regulator was added.

Comparative Example 4 Except that steam heating in the heating device was not performed,
An extruded foam board was formed in the same manner as in Example 2.

Table 1 shows the blending amounts of the respective foaming agents, the temperature of the heat molding tool, and the temperature in the heating device in Example 2 and Comparative Examples 1 to 4.
The apparent density of the obtained extruded foam board, the thickness direction cell diameter in the surface layer and the center in the thickness direction, the apparent density in the upper and lower surface layers and the center in the thickness direction, temperature 70 ° C, relative humidity 97%,
Table 3 shows the heating dimensional change and the thermal conductivity of the entire extruded foam plate, the upper and lower surface layers, and the center in the thickness direction under the conditions of 7 days.

[0090]

The extruded polystyrene resin foam plate of the present invention is obtained by heating, melting and kneading a polystyrene resin and a mixed foaming agent containing 1,1,1,2-tetrafluoroethane using an extruder. 20m thickness obtained by extrusion
m, and an extruded polystyrene resin foam board having an apparent density of 25 to 40 kg / m ³ . Therefore, the extruded foam board of the present invention does not destroy the ozone layer and also maintains the heat insulating property for a long time.

The extruded polystyrene resin foam board of the present invention has a heating dimensional change under conditions of a temperature of 70 ° C., a relative humidity of 97% and 7 days at both the surface layer and the center in the thickness direction of the foam board. ~ 1.5%. The foamed board of the present invention exhibits excellent dimensional stability even when used at a high temperature because the dimensional change upon heating at 70 ° C. is small.

The average cell diameter in the thickness direction of the surface layer of the extruded polystyrene resin foam board of the present invention is 0.15 to 0.45 m.
The residual amount of m, 1,1,1,2-tetrafluoroethane is 0.3 to 0.75 mol per 1 kg of polystyrene resin. Therefore, while being excellent in dimensional stability and heat insulation, heat insulation is maintained for a long time.

In the extruded polystyrene resin foam board of the present invention, the ratio (L ₁ / L) of the average cell diameter L _{1 in} the surface layer portion of the extruded foam board to the average cell diameter L _{2 in the} center in the thickness direction of the foam board is obtained.
L ₂ ) is 0.7 to 1.0, the apparent density D ₁ of the surface layer of the extruded foam board and the apparent density D _{2 of the} center of the extruded foam board in the thickness direction.
When the ratio (D ₁ / D ₂₎ is to employ a configuration that it is 0.9 to 1.1 with, it is possible to obtain a more Sunfu stability, particularly excellent extrusion foam plate heat insulation.

The method for producing an extruded polystyrene resin foam board of the present invention is characterized in that a polystyrene resin and a mixed foaming agent containing 30 to 55 mol% of 1,1,1,2-tetrafluoroethane are mixed by using an extruder. After heating, melting and kneading to form a foamable molten resin mixture, the molten resin mixture is extruded from a die lip, and the molten resin mixture is further passed through a heating molding tool attached to the extruder tip to form a plate-like foam. After that, by adopting a configuration in which the plate-like foam is heated and expanded in a heating device to form an extruded foam plate, the extruded polystyrene resin foam plate can be efficiently manufactured.

In the above production method, if the average cell diameter in the thickness direction of the surface layer portion of the plate-like foam is 0.1 mm or more, the extruded polystyrene resin foam plate can be produced more reliably. it can.

In the method for producing an extruded polystyrene resin foam board of the present invention, if the plate-like foam is heated and expanded by steam in a heating device, the foam can be efficiently expanded in a short time. In addition, the difference in apparent density between the surface layer portion and the inside in the thickness direction can be made uniform, and the residual stress in the surface layer portion can be removed. as a result,
The length in the heating device can be shortened, and deterioration of the surface of the extruded foam plate due to overheating can be prevented.

In the production method of the present invention, the temperature of the heat-molding tool is adjusted to “the Vicat softening temperature of the base resin −15 ° C.” to “the Vicat softening temperature of the base resin + 30 ° C.” Vicat softening temperature of base resin -15 ° C ”
~ When the temperature is controlled to "Vicat softening temperature of base resin + 10 ° C", the apparent density difference between the surface layer and the inside of the thickness direction is made uniform while heating and expanding the plate-like foam, and the residual stress in the surface layer is reduced. It can be reliably removed, and flow marks and burns on the surface of the plate-like foam can be reliably prevented.

In the production method of the present invention, the mixed blowing agent is composed of 30 to 55 mol% of 1,1,1,2-tetrafluoroethane and 0 to 30 of isobutane and / or normal butane.
Mol% and methyl chloride and / or methyl chloride 15 to 70
Mol% (the total amount of these blowing agents is 1
00 mol%. By adopting the configuration of (1), it is possible to easily produce the extruded polystyrene resin foam board of the present invention, which is excellent in heat insulation and flame retardancy.

[Brief description of the drawings]

FIG. 1 is a drawing showing an example of an apparatus used for a method for producing a polystyrene resin foam board of the present invention.

FIG. 2 is an explanatory diagram of a method of measuring “sludge”.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die lip 2 Foamable molten resin mixture 3 Heat molding tool 4 Heating device 5 Plate foam 6 Extruded foam board

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B29L 7:00 B29L 7:00 C08L 25:04 C08L 25:04 (72) Inventor Naotochi Kogure Kanuma, Tochigi Prefecture 10-3 Satsuki-cho, Japan JSP Kanuma Research Institute Co., Ltd. (72) Inventor Masato Naito 10-3 Satsuki-cho, Kanuma City, Tochigi Prefecture JSP Kanuma Research Institute Co., Ltd. F-term (reference) CC04Y DA02 DA03 DA32 4F207 AA13 AB02 AG01 AG20 AK01 AR06 AR11 AR12 AR15 AR20 KA01 KA12 KK04 KK45 KK51 KM15 KM16

Claims (7)

[Claims] 1. A foamable molten resin mixture containing a mixed foaming agent containing 1,1,1,2-tetrafluoroethane and a polystyrene-based resin and having a thickness of at least 20 mm obtained by extruding from a high pressure region to a low pressure region. Apparent density 25-40k
g / m ^3, a polystyrene resin extruded foam plate having an average cell diameter of 0.15 in the thickness direction of the surface layer of the extruded foam plate.
~ 0.45 mm, and 1,1,1,
The residual amount of 2-tetrafluoroethane is 0.3 to 0.75 mol / kg of polystyrene resin,
The heating dimensional change required by standing for 7 days at a temperature of 97 ° C. and a relative humidity of 97% is −1.5 to 1.5% for both the surface layer and the center in the thickness direction of the extruded foamed board. Characterized by extruded polystyrene resin foam board. _2. The ratio (L ₁ / L ₂ ) between the average cell diameter L _{1 in} the thickness direction of the surface layer of the extruded foam plate and the average cell diameter L _{2 in} the thickness direction at the center in the thickness direction of the extruded foam plate. Is 0.7 to 1.0
And the ratio (D ₁₎ of the apparent density D ₁ of the surface layer portion of the extruded foam plate to the apparent density D ₂ of the extruded foam plate at the center in the thickness direction.
/ D ₂₎ is extruded polystyrene resin foam plate according to claim 1, characterized in that 0.9 to 1.1. 3. An extrudable molten resin mixture containing a mixed foaming agent containing 30 to 55 mol% of 1,1,1,2-tetrafluoroethane and a polystyrene-based resin is extruded from the extruder tip to reach the extruder tip. 2. The extruded polystyrene resin foam according to claim 1, wherein the foamed sheet is made into a plate-like foam by passing through an attached heating molding tool, and then the plate-like foam is introduced into a heating device to be heated and expanded. Plate manufacturing method. 4. The method for producing an extruded polystyrene resin foam board according to claim 3, wherein the average cell diameter in the thickness direction of the surface layer portion of the plate-like foam is 0.1 mm or more. 5. The method for producing an extruded polystyrene resin foam plate according to claim 3, wherein the plate-like foam is heated and expanded by steam in a heating device. 6. The temperature of the heat molding tool is adjusted to “the Vicat softening temperature of the polystyrene resin −15 ° C.” to “the Vicat softening temperature of the polystyrene resin + 30 ° C.”, and the inside of the heating device is “the polystyrene resin”. The extruded foamed polystyrene resin board according to any one of claims 3 to 5, wherein the temperature is adjusted to "Vicat softening temperature of the resin -15C" to "Vicat softening temperature of the polystyrene resin + 10C". Manufacturing method. 7. The mixed blowing agent comprises 30 to 55 mol% of 1,1,1,2-tetrafluoroethane, 0 to 30 mol% of isobutane and / or normal butane, methyl chloride and / or ethyl chloride 15 ７０70 mol% (provided that the total amount of these blowing agents is 100 mol%).
The method for producing an extruded polystyrene resin foam board according to any one of claims 3 to 6, wherein: