JP2003025407A - Styrenic resin foam and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide styrenic resin foam having high heat insulating properties and fire retardancy equal to those of foam using a fluorocarbon without using the fluorocarbon as a foaming agent, and a method for manufacturing the same. SOLUTION: The styrenic resin foam is obtained by extruding a styrenic resin containing a hydrocarbon and alkyl chloride as the foaming agent into a plate shape while foaming the same and characterized in that a mean air bubble diameter ϕAV is 0.10-0.50 mm, the ratio ϕVD/ϕAV of the air bubble diameter ϕVD in the thickness direction of the plate and ϕAV is 0.8-<1.2 and the residual gas quantity of the hydrocarbon is set to 3.5 wt.% or less. The styrenic resin foam is manufactured by extruding the styrenic resin with an MFR of 4-10 g/10 min and a die well ratio at a shearing speed of 200 s<-1> is not less than 1.8 into the plate shape using the foaming agent while foaming the same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene resin foam excellent in heat insulation and flame retardance, which is used as a heat insulation material in the construction field, for example, and a manufacturing method thereof.

[0002]

2. Description of the Related Art The above-mentioned heat insulation materials are the Japanese Industrial Standard J
IS A9511 _-1995 The type of plastic used and the manufacturing method
It is classified into several types depending on the shape and the like, and among them, there is an extruded polystyrene foam heat insulating plate manufactured by extruding and foaming a styrene resin in a plate shape. Further, this extruded polystyrene foam heat insulating plate is further subdivided into 6 types from 1 type a, b to 3 types a, b depending on the difference in thermal conductivity and other characteristics in the thickness direction (VD) of the plate.

Of these, the extruded polystyrene foam heat insulating plates classified into two types a and b are required to have a VD thermal conductivity of 0.034 W / m · K or less at an average temperature of 20 ° C. Further, the extruded polystyrene foam heat insulating plate classified into three types a and b is required to have a VD thermal conductivity of 0.028 W / m · K or less at an average temperature of 20 ° C. In order to manufacture an extruded polystyrene foam heat insulating plate classified into 2 types a, b and 3 types a, b having such a low thermal conductivity, CFC is generally used as a foaming agent.

CFCs have a low thermal conductivity and a low permeability to styrene resins, and can be present in the bubbles after extrusion foaming for a long period of time, that is, the gas retention in the bubbles over time is good. Therefore, it is effective in suppressing the thermal conductivity of the heat insulating plate. Also, CFCs are less likely to burn than hydrocarbons,
HFC-134a, etc., which will be described later, are nonflammable, which is another characteristic required for the heat insulating plate.
Is also effective for achieving flame retardancy to clear the defined flammability criteria IS A9511 _-1995.

As CFCs, HCFCs such as 1-chloro-1,1-difluoroethane (HCFC-142b) are currently used in place of the specified CFCs whose production and consumption are completely abolished because they have a strong ozone depleting effect. CFC alternatives are widely used. However, the alternative CFCs for HCFCs still have an ozone depleting effect, and thus their use is in the direction of being restricted, and there is an urgent need to switch to alternative CFCs for HFCs.

[0006] The CFC substitute for HFCs represented by 1,1,1,2-tetrafluoroethane (HFC-134a) is trichlorofluoromethane (CFC-11), which is a numerical value of the degree of influence on ozone layer depletion. This is because it is considered that the ozone layer depletion coefficient with 0 is 0 and there is no influence on the ozone layer. However, CFC substitutes for HFCs have another problem that the global warming coefficient with carbon dioxide as 1 is extremely high at 1,000 to 10,000 or more, which is a numerical value of the degree of influence on global warming.

For this reason, in consideration of the influence on the global environment, no thermal chlorofluorocarbon is used, and the thermal conductivity thereof is as low as that of the one using chlorofluorocarbon. Specifically, the above-mentioned two kinds a, b or 3 are used. Various studies have been conducted in order to obtain a styrene resin foam having a high heat insulating property required for extruded polystyrene foam heat insulating plates of the species a and b.

[0008]

As a foaming agent that replaces CFCs, hydrocarbon-based foaming agents such as propane, butane, and pentane are considered. Hydrocarbon-based blowing agents
Its thermal conductivity is as small as that of chlorofluorocarbon, and it has good gas retention in bubbles over time, has no ozone layer depleting effect, and has a global warming potential that is that of chlorofluorocarbon alternative to HFCs. It is about a few hundredths.

Therefore, in the extrusion foaming method, it is possible to manufacture a styrene resin foam having excellent heat insulating properties, which is equivalent to the case of using CFC, while suppressing the influence on the global environment as much as possible. However, since hydrocarbons are flammable, unlike fluorocarbons, it is not possible to obtain foams with excellent flame retardance that meet the above-mentioned criteria for flammability, and also the safety during foam production is affected. is there.

Therefore, it has been considered to produce a foam by using a hydrocarbon in combination with an alkyl chloride which is flame-retardant and has a low thermal conductivity and a good foaming property. For example, JP-A-51
Sample No. 1 in the examples of Japanese Patent Publication No. 92871. In 4 to 8, propane, butane or pentane among hydrocarbons and methyl chloride which is alkyl chloride are contained in a weight ratio of 7:
It is used in a ratio of 3 to produce a styrene resin foam.

It can be seen from the results in Table 2 of the above publication that the produced foam has a low thermal conductivity and an excellent heat insulating property. That is, from Table 2, sample No. 4-8
In each case, the thermal conductivity (24 ° C.) immediately after extrusion foaming and 5 years later is 0.0242 kcal / (m · h).
r.degree. C.) [.apprxeq.0.0281 W / m.K], which is within the range below, and it is understood that the high heat insulating property required for the extruded polystyrene foam heat insulating plate of the 2nd type a and b is achieved. To be done.

However, in Table 1, the partial pressure of the specific foaming agent (hydrocarbon in this case) at the time of molding is 0.26 to 0.39 at the total pressure of 1.04 atm, or the total pressure of 1.05 atm. Since it is as high as 0.28 atm in atmospheric pressure, it is also clear that these foams still have a large amount of hydrocarbon residual gas and insufficient flame retardancy. Also, in the same manner, JP-A-53-25
No. 64 of the example of the publication. In 23 and 24,
Propane or butane and methyl chloride are used as a foaming agent to produce a styrene resin foam.

According to the results shown in Table 1 of the above publication, the produced foam had a thermal conductivity (24 ° C.) from 3 days after extrusion foaming to 5 years later, which was No. 23 at 0.0250 kc
al / (m ・ hr ・ ° C) [≒ 0.0291W / m ・ K]
Hereinafter, No. 24 at 0.0249 kcal / (m · hr
.Degree. C.) [.apprxeq.0.0290 W / m.K] or less, both of which fall within the ranges of the above two types a and b.
It can be seen that the high heat insulating property required for the extruded polystyrene foam heat insulating plate is achieved.

However, as shown in the table, since the partial pressure values of butane or propane after 3 days of extrusion foaming are as high as 0.40 atmosphere and 0.89 atmosphere in 1 atmosphere, respectively, these foaming It is clear that the body is still high in hydrocarbons and not sufficiently flame retardant. JP-A-1
0-265604 discloses hydrocarbons of 5-40% by weight.
And 95-60% by weight of ethyl chloride to produce a styrene resin foam. Thus, it is considered that the flame retardancy of the foam can be improved by reversing the amounts of the hydrocarbon and the alkyl chloride.

However, in column 0034 of the above publication, the thermal conductivity at an average temperature of 20 ° C. is 0.034 kcal /
If (m · hr · ° C.) [≈0.040 W / m · K] or less, the heat insulating property is good (∘), which is a standard of heat insulating property. This is because, in the JIS A9511 _-1995, which is the lowest thermally insulating one a, heat insulating standards expected of extruded polystyrene foam insulation board which is classified into b. From this, it is understood that when the amounts of the hydrocarbon and the alkyl chloride used are reversed, the heat insulating property deteriorates.

[0016] The cause of this is that the gas retention in the bubbles with time is not good like CFCs and hydrocarbons because of the high permeability of alkyl chlorides to styrene resins. That is, since the alkyl chloride has high permeability to the styrene-based resin as described above, it is likely to be lost early in the bubbles after extrusion and foaming, and there is no effect in reducing the thermal conductivity. For this reason, if a large amount of alkyl chloride is used, the heat insulating property will decrease.

An object of the present invention is to provide a styrene resin foam which does not use CFC as a foaming agent and has high heat insulation and flame retardancy equivalent to those using CFC, and a method for producing the same. To do.

[0018]

In order to solve the above-mentioned problems, the inventor has used hydrocarbon and alkyl chloride as a blowing agent, and has the above-mentioned contradictory properties of heat insulation and flame retardancy. Various studies were conducted in order to achieve compatibility with both properties.
In other words, although the thermal conductivity is small and the gas retention in the bubbles over time is good, the amount of flammable hydrocarbons is kept to the necessary minimum to maintain sufficient flame retardancy, In order to cover the effect of the increase in thermal conductivity due to the loss of alkyl from the bubbles and to maintain high heat insulation, other components other than the foaming agent were investigated.

Then, it was found that the cell structure of the foam is greatly related to its heat insulating property. That is, by increasing the number of VD bubbles required to have a predetermined heat insulating property in the plate-like foam and increasing the number of times of blocking heat in the bubble film separating the bubbles, the heat insulating property in the same direction can be improved. . However, in order to increase the number of cells, simply reducing the cell diameter cannot provide a foam having a sufficient thickness. Further, when the discharge amount of the resin during extrusion foaming is increased in order to secure a sufficient thickness, the bubbles extend along VD and have a shape standing in the same direction. Therefore, the number of bubbles in VD does not increase so much, and the effect of increasing the number of times of blocking heat in the bubble film and improving the heat insulating property in the same direction cannot be obtained.

Then, as a result of further studying the bubble structure, formula (1): φAV = (φMD + φTD + φVD) / 3 (1) [wherein, φMD is the bubble diameter in the extrusion flow direction, φTD is the bubble diameter in the width direction of the plate, φVD represents the bubble diameter in the thickness direction of the plate. ] The average bubble diameter φAV obtained by
Specified within 50 mm, φVD and φAV
If the ratio φVD / φAV is defined within the range of the formula (2): 0.8 ≦ φVD / φAV <1.2 (2), the heat of the bubble film can be maintained while ensuring the sufficient thickness of the foam. It was found that the number of interruptions can be increased to improve the heat insulating property of VD.

Therefore, the styrenic resin foam of the present invention is formed by extruding and foaming a styrenic resin into a plate shape using a foaming agent containing at least hydrocarbon and alkyl chloride. The average bubble diameter φAV obtained by the equation (1) is within the range of 0.10 to 0.50 mm, and φVD
The ratio of φVD / φAV is within the range of the above formula (2), and the residual gas amount of hydrocarbons is 3.5% by weight or less of the total amount of the foam.

In the present invention, the residual amount of hydrocarbon is limited to 3.5% by weight or less of the total amount of the foam.
This is to impart sufficient flame retardancy to the foam. That is, if the residual gas of the hydrocarbon is flammable within this range, as is clear from the results of Examples appearing later, clearing defined flammability criteria described above, JIS A9511 _-1995 flame Flammability can be achieved. Considering that the flame retardancy of the foam is further improved, the residual amount of hydrocarbons is preferably 3.0% by weight or less of the total amount of the foam, even within the above range.

Further, in order to add the adiabatic effect of the hydrocarbon gas remaining in the bubbles to the adiabatic effect of the aforesaid bubble structure to ensure good adiabaticity, the residual gas amount of the hydrocarbon is Within the range, especially 1.0 of the total amount of foam
It is preferably at least wt%. The reason why the average bubble diameter φAV calculated by the equation (1) is limited to the range of 0.10 to 0.50 mm is as follows.

That is, the average bubble diameter φAV is 0.10 m.
If it is less than m, the bubble diameter is too small and the number of times of blocking heat in the bubble film increases, but the thickness of each bubble film becomes small, and the heat blocking effect in each bubble film decreases. For this reason, the heat insulating property of VD rather deteriorates.
On the other hand, when the average bubble diameter φAV exceeds 0.50 mm, the bubble diameter is too large, and the number of times of blocking heat in the bubble film is reduced, so that the heat insulating property of VD is also deteriorated.

On the other hand, the average bubble diameter φAV is 0.10.
Within the range of 0.50 mm to 0.50 mm, it is possible to improve the heat insulating property of the foam by increasing the number of times of blocking heat in the bubble film as described above. Therefore, in order to limit the residual gas amount of hydrocarbons to 3.5% by weight or less of the total amount of the foam as described above,
By increasing the amount of alkyl chloride, the effect of increasing the thermal conductivity due to the loss of the alkyl chloride from the bubbles is covered, and in addition to the adiabatic effect of the hydrocarbon gas remaining in the bubbles, It is possible to impart high heat insulation to the foam.

Considering that the average bubble diameter φAV improves the heat insulating property of the foam by increasing the number of times of blocking heat in the bubble film, it is particularly 0.20 to 0.40 within the above range.
It is preferably mm. Further, the ratio φVD / φAV of φVD / φAV is limited within the range of the equation (2): 0.8 ≦ φVD / φAV <1.2 (2) for the following reason.

That is, when the ratio φVD / φAV is less than 0.8, the bubbles have a shape crushed by VD, so that a foam having a sufficient thickness cannot be obtained. It may be possible to increase the discharge rate of the resin during extrusion foaming in order to secure a sufficient thickness, but this requires a considerable discharge rate, and the current equipment for extrusion foaming (extruder etc.) If it is used as it is, the production becomes substantially difficult. On the other hand, when the ratio φVD / φAV is 1.2 or more, the bubbles become VD
It will be a fairly standing shape. Therefore, the number of bubbles in VD does not increase so much, and the effect of increasing the number of times of blocking heat in the bubble film and improving the heat insulating property in the same direction cannot be obtained.

On the other hand, when the ratio φVD / φAV is in the range of 0.8 or more and less than 1.2, the number of bubbles in the same direction is increased while sufficiently ensuring the VD thickness of the foam. By increasing the number of heat cutoffs in the bubble film,
The heat insulation of the foam can be improved. Therefore, loss of the alkyl chloride from the bubbles by increasing the amount of the alkyl chloride in order to limit the residual gas amount of the hydrocarbon to 3.5% by weight or less of the total amount of the foam as described above. It becomes possible to give the foam a high heat insulating property by covering the influence of the increase in the thermal conductivity due to the above and further adding the heat insulating effect by the hydrocarbon gas remaining in the bubbles.

The ratio φVD / φAV is preferably 0.9 or more in the above range in view of ensuring a sufficient VD thickness of the foam. Further, considering that the heat insulating property of the foam is further improved by increasing the number of VD bubbles and increasing the number of times of blocking heat in the bubble film, it is particularly 1.1 or less within the above range. Preferably. In order to produce the styrene resin foam of the present invention, various methods such as adjusting the conditions of extrusion foaming can be adopted. Particularly, as the styrene resin, MFR is 4 to 10 g / 10 min, and It is preferable to use a styrene resin having a die swell ratio of 1.8 or more at a shear rate of 200 s ⁻¹ .

That is, in the method for producing a styrene resin foam of the present invention, at least a styrene resin having an MFR of 4 to 10 g / 10 min and a die swell ratio of 1.8 or more at a shear rate of 200 s ^-1 is used. It is characterized in that a foaming agent containing a hydrocarbon and an alkyl chloride is used to perform extrusion foaming in a plate shape. According to such a manufacturing method, using the same equipment such as an extruder as in the past, while maintaining the same conditions of extrusion foaming as in the past, simply by changing the resin,
There is an advantage that it is possible to produce the foam of the present invention having high heat insulation and flame retardancy equivalent to those using chlorofluorocarbon.

In the production method of the present invention, the MFR of the styrene resin is limited to 4 to 10 g / 10 min for the following reason. That is, styrene-based resin MF
If R is less than 4 g / 10 min, the resin viscosity becomes large and the pressure inside the extruder rises. As a result, the discharge amount of the resin at the time of foaming by extrusion decreases, and the productivity becomes extremely poor. On the other hand, MFR of styrene resin is 10g / 1
If it exceeds 0 min, the resin does not have a melt tension capable of withstanding high foaming in the plate-shaped foam, and thus a problem that a plate-shaped foam with a high magnification cannot be obtained occurs.

Considering the balance of these problems,
Considering the production of a foam having high heat insulation and flame retardancy, the MFR of the styrene resin is preferably 5 to 8 g / 10 min even within the above range. In the present invention, Japanese Industrial Standard JIS K7210 _-1999 - measured in accordance with the B method of Shosai test method in "Plastics Test Methods of thermoplastics melt mass flow rate (MFR) and melt volume flow rate (MVR)" The value obtained is taken as the MFR of the styrene resin. Details of the measuring method will be described later.

The shear rate of styrene resin is 200
The reason why the die swell ratio at s ⁻¹ hour is limited to 1.8 or more is as follows. The shear rate of 200 s ^-1 corresponds to the minimum shear rate for extrusion-foaming a plate-shaped foam,
If the die swell ratio at that time is less than 1.8, a foam having a sufficient thickness cannot be obtained. Further, when the discharge amount of the resin during extrusion foaming is increased in order to secure a sufficient thickness, the bubbles extend along VD and stand in the same direction as described above. It does not increase so much, and the effect of improving the heat insulation in the same direction by increasing the number of times of blocking heat in the bubble film cannot be obtained.

On the other hand, when a styrene resin having a die swell ratio of 1.8 or more at a shear rate of 200 s ⁻¹ is used, the same equipment for extrusion and foaming as the conventional one is used, and the same extrusion and foaming as the conventional one is used. It is possible to obtain a plate-like foam having a sufficient thickness while maintaining the above conditions. The obtained foam has a good cell shape that satisfies the above-described formulas (1) and (2), and has high heat insulation and flame retardancy. In addition, in order to increase the effect of improving the heat insulating property in the same direction by increasing the number of times of blocking heat in the bubble film and further improving the heat insulating property of the foam, a shear rate of 20
Even within the above range, the die swell ratio at ^{0 s −1} is preferably 1.9 or more.

As the die swell ratio is increased, the V of the foam molded to a predetermined thickness through a molding device such as two plates arranged at a predetermined interval during extrusion foaming.
More bubbles can be arranged in D. Therefore, it becomes possible to further improve the heat insulating property of the foam. Therefore, it is desirable that the die swell ratio is large, but as the resin having a large MFR in the range of 4 to 10 g / 10 min and a large die swell ratio, there is currently about 2.1.

In this invention, the Japanese Industrial Standard JIS
K7199 _-1999 - the "plastic capillary rheometer and slit die rheometer flow characteristics test method for plastic by meter" has a value measured in accordance with the Shosai test methods, and that the die swell ratio of the styrene resin. Details of the measuring method will be described later.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below. [Styrene-based resin foam] The styrene-based resin foam of the present invention is mainly formed in a plate shape. The values of the physical properties, defined in JIS A9511 _-1995 described above, has two a, b to three a, thermal insulation and flame retardancy required for extruded polystyrene foam insulation board which is classified into b Is preferred.

Specifically, the thermal conductivity (average temperature 20 ° C.) of 60 days after extrusion foaming is 0.034 W /
m · K or less, and preferably an average value of the flame out time in the flammability test of the measurement method A defined in JIS A9511 _-1995 is less than 3 seconds. The smaller the thermal conductivity is, the more preferable it is. The lower limit value is not particularly limited, but the thermal conductivity at the time point after 60 days is 0.027.
If it is made to be W / m · K or less, it is necessary to use a large amount of hydrocarbon, and as a result, flame retardancy may be deteriorated.

In this invention, the Japanese Industrial Standard JIS
A1412 _-1994 Value obtained from the heat flow rate measured by the flat plate heat flow meter method specified in "Measurement method of thermal conductivity and thermal resistance of heat insulating material" and the temperature difference between the upper and lower surfaces of the test piece at that time Is the thermal conductivity of the foam. Details of the measuring method will be described later. The thickness of the foam plate is preferably 25 mm or more and less than 110 mm. The thickness of the plate is 2
If the thickness is less than 5 mm, the production is not easy, and it is difficult to ensure the above-mentioned heat insulation, which is not preferable. Further, when the thickness is 110 mm or more, the bubbles have a shape that stands up considerably on the VD, and the number of bubbles in the VD does not increase so much, so the effect of increasing the number of times the heat is blocked in the bubble film and improving the heat insulation in the same direction. May not be obtained.

The thickness of the plate is preferably 80 to 100 mm within the above range in order to obtain a foam having the highest heat insulation in consideration of the balance of these characteristics. <Styrene Resin> As the styrene resin forming the foam, any of various styrene resins conventionally known in the art can be used.

Examples of such styrene resins include styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene,
Examples thereof include homopolymers or copolymers of chlorostyrene, bromostyrene, vinyltoluene and vinylxylene. Further, copolymers of these styrene-based monomers and other vinyl monomers can also be used. Examples of other vinyl monomers include acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, maleic anhydride, acrylamide and the like.

Further, if the styrene resin is the main component, a mixed resin obtained by adding and mixing another resin can also be used. As the mixed resin, for example, in order to improve the impact resistance of the foam, a polyene, a styrene-butadiene copolymer, an ethylene-propylene-a non-conjugated diene terpolymer such as a diene rubbery polymer. Examples of the rubber-modified styrene resin added, so-called high-impact polystyrene, and the like. The physical property value of the styrene resin is not particularly limited. However, in order to produce a good foamed product under the same extrusion conditions as before, using the same equipment as before, as described above, the MFR of the styrene resin is 4 to 10 g / 10.
It is preferable that the die swell ratio is 1.8 or more at the time of min and the shear rate of 200 s ⁻¹ .

<Blowing agent> As the blowing agent, hydrocarbon and alkyl chloride are used together as described above. Among them, hydrocarbons include, for example, propane, butane [n-butane, i-butane, or a mixture of both (mixed butane)], pentane, isopentane, hexane, isohexane, heptane, isoheptane, etc. 8
Some hydrocarbons are included. Among them, propane, butane, pentane and the like are preferably used, and butane is particularly preferably used.

Examples of the alkyl chloride include methyl chloride and ethyl chloride, and methyl chloride is particularly preferably used. Further, in the present invention, another foaming agent may be added within a range that does not impair the effect of the combined use of the above-mentioned hydrocarbon and alkyl chloride. Examples of other foaming agents include inorganic gases such as carbon dioxide, nitrogen, water, argon and helium, ethers such as dimethyl ether and diethyl ether, alcohols such as methanol and ethanol, ketones such as dimethyl ketone, methyl ethyl ketone and diethyl ketone. And the like.

The composition of the foaming agent containing each of the above components is not particularly limited, but in order to keep the residual gas amount of the hydrocarbon within the above range, the total amount of the foaming agent to be used contains 20 to 20 hydrocarbons.
40% by weight and 80-60% by weight of methyl chloride are preferred. <Additive> The foam of the present invention may contain various conventionally known additives. Examples of the additive include a bubble nucleating agent, an ultraviolet absorber, an antioxidant, a coloring agent, a lubricant, a flame retardant, an antistatic agent and the like. Among them, as the bubble nucleating agent, for example, an inorganic powder such as talc or silica is preferable.

The amount of the additive compounded is appropriately set. [Foam Production Method] As a production method for producing the foam of the present invention using the above-mentioned components, extrusion foaming is employed as described above. Among them, as described above, extrusion foaming is performed using a styrene resin having a melt mass flow rate (MFR) of 4 to 10 g / 10 min and a die swell ratio of 1.8 or more at a shear rate of 200 s ^−1. It is preferable to manufacture by the manufacturing method of. In this case, as described above, using the same equipment as the conventional one, and maintaining the same conditions of extrusion foaming as the conventional one, just by replacing the resin with the above resin, it is equivalent to using CFC. The foam of the present invention having high heat insulation and flame retardancy can be produced.

In extrusion foaming, first, the styrene resin is supplied to an extruder together with an additive, if necessary, and melt-kneaded. Next, a foaming agent is added to the melt-kneaded resin and further melt-kneaded. After adjusting the temperature suitable for foaming, the foam of the present invention is manufactured by extruding and foaming into a plate shape through the die of the mold. The conditions for extrusion foaming, such as the amount of resin discharged, are set in the same manner as in the conventional case as described above.

In order to adjust the thickness of the foam extruded and foamed from the die of the mold to the above-mentioned predetermined range, the foaming body immediately after extrusion is formed by disposing two plates at predetermined intervals. The method of cooling simultaneously with molding is suitably adopted.

[0049]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. The MFR of the styrenic resin used in the examples and comparative examples is as described in JIS K7210.
_-It was measured as follows according to the test method _published in ₁₉₉₉ . <MFR Measurement> As a measuring device, an extrusion type plastometer (capillary rheometer) conforming to the same standard was used. Then, when the styrene resin was extruded under the conditions of the test temperature θ = 200 ° C. and the nominal load (combination) M _nom = 5.00 kg, M was calculated from the distance and time the piston moved.
FR was calculated.

Shear rate of styrene resin is 200
As described above, the die swell ratio at s ⁻¹ hour is
In accordance with the Shosai test method in S K7199 _-1999, it was measured as follows. <Measurement of Die Swell Ratio> An extrusion rheometer with a capillary die [Capirograph PMD-C manufactured by Toyo Seiki Seisaku-sho] conforming to the same standard was used as a measuring device. Also, for the capillary die, the inner diameter D _C = 1.0
mm, length L = 10 mm, and inflow angle of 90 ° were used. The measurement conditions are test temperature θ = 200 ° C. and preheating time 5
The extrusion rate was 1.5 to 500 mm / min (shear rate 1.8 to 6080 s ⁻¹ ).

The measurement is carried out by measuring the diameter D _S (mm) of the extruded strand by extruding the resin from the tip of the capillary die while maintaining the extrusion rate at a constant value within the above range. Repeatedly doing. And each measured value of the diameter D _S of the extruded strand,
From the inner diameter D _C (= 1.0 mm) of the capillary die,
Formula (3): Die swell ratio = D _S / D _C The die swell ratio of the resin obtained by (3) is plotted for each extrusion rate to create a graph, and from this graph, a shear rate of 200 s ⁻¹ hour is obtained. The die swell ratio was determined.

Next, the average cell diameter φAV and the cell diameters φMD, φTD and φVD in each direction, which are the basis for calculating the ratio φVD / φAV, of the foams produced in Examples and Comparative Examples are AS.
TMD2842-69 "Standard Method of Test for
It was measured as follows in accordance with the test method described in "WATER ABSORPTION OF RIGID CELLULAR PLASTICS". <Measurement of cell diameter> First, the foam is MD (extrusion flow direction),
And TD (width direction of the plate), and each cut surface is a scanning electron microscope [JS manufactured by JEOL Ltd.]
[MT-300].

Next, in the photograph taken, the above M
The average chord length (t) of bubbles was determined from the number of bubbles on a straight line (60 mm) along each of D, TD, and VD (thickness direction of the plate). Average chord length (t) = 60 / (number of bubbles × magnification of photograph) Then, according to the following equation, bubble diameters in the above three directions (d = φMD,
φTD or φVD) was calculated.

D = t / 0.616 Further, after extrusion foaming of the foams produced in Examples and Comparative Examples,
Thermal conductivity after 60 days (average temperature 20 ℃)
, The in accordance with the test method Shosai to JIS 1412 _-1994 as it was measured as follows. <Measurement of Thermal Conductivity> A foam body 60 days after extrusion foaming has a thickness of 25 m along VD except for the skin portion.
m, the length along MD and the width along TD are both 20
A test piece was prepared by cutting it to 0 mm.

Next, this test piece was set between the two flat plates of the two-plate flat heat flow meter based on the flat plate heat flow meter method described above. Then, one flat plate was measured as a high-heat plate and the other flat plate was measured as a low-heat plate, and from the heat flow rate flowing through the test piece and the temperature difference between the upper and lower surfaces of the test piece at that time, the foam temperature at an average temperature of 20 ° C. The thermal conductivity (0.034 W / mK) was determined. Further, the flame retardancy of the foams produced in Examples and Comparative Examples is
As described above, according to the flammability test of the measurement method A defined in JIS _A9511-1995 , the average value of the extinction time measured as described below was used for evaluation.

<Evaluation of Flame Retardancy> After extruding and foaming, one week has passed, excluding the skin, the foam has a thickness of 10 mm along VD, a length of 200 mm along MD, and a width of 25 mm along TD. After cutting so as to have 5 pieces, 5 test pieces each having an ignition limit indicator line and a combustion limit indicator line were prepared. Next, with each test piece fixed, the flame of a candle for a fire source was applied to the tip of the test piece, and the candle was moved horizontally at a constant speed to the ignition limit indicator line for about 5 seconds, It was quickly retracted, and the time from that moment until the flame disappeared (flame-extinguishing time) was measured.

After repeating this operation for all of the five test pieces, the average value of the flame-extinguishing time of the five test pieces was obtained, and the flame retardancy was evaluated based on the length. J
IS A9511 To clear a defined flammability criteria _-1995, the average value of the flame out time, as the shall not exceed 3 seconds. Further, the residual gas amount of hydrocarbons of the foams produced in Examples and Comparative Examples was first measured as follows.

<Measurement of Residual Gas Amount of Hydrocarbons I> Foamed one week after extrusion foaming is compressed in a closed container to expel gas in bubbles, and the exhaust gas is quantitatively analyzed by a gas chromatograph method. Then, the amount of residual gas of hydrocarbon was calculated with respect to the total amount of foam. In the above measuring method, the amount of compression when compressing the foam, the deviation of the measurement conditions such as temperature,
There is a possibility that the measured value may vary by about 7 to 10%. Therefore, in the above measurement I, in order to ensure accuracy, the average value of the measurement values obtained by performing the measurement 10 times while maintaining the measurement conditions as constant as possible in each of the examples and the comparative examples is calculated as the residual gas amount. However, in order to make it more accurate, the following measurement II was performed to confirm whether or not the result of the above measurement I was accurate.

<Measurement of residual amount of hydrocarbon II> A gas chromatograph equipped with a pyrolysis furnace [PYR-1A manufactured by Shimadzu Corporation] as a measuring apparatus [G manufactured by Shimadzu Corporation]
C-14B] was used. Also, as the column, POLAPACK-Q [manufactured by Waters, (80/100) inner diameter 3 m
mφ × length 1.5 m] and a thermal conductivity type detector was used. Then, after extrusion foaming, one week after the foam is cut into a rectangular parallelepiped of 5 mm × 5 mm × 35 mm and weighed, it is put in the pyrolysis furnace of the above measuring device,
The pyrolysis gas obtained by pyrolyzing the foam was analyzed under the following measurement conditions, and the residual gas amount of hydrocarbons was determined from the measurement results. The measurement was performed three times for each of the examples and comparative examples, and the average value of the measured values for each time was calculated as the residual gas amount.

(Measurement conditions) Pyrolysis furnace temperature: 150 ° C. Column temperature: 100 ° C. Injection temperature: 120 ° C. Carrier gas: Helium carrier gas flow rate: 1 ml / min As shown in Table 2, the results of both of the above measurements are decimal points. It was confirmed by the measurement II that the rounded values up to the first place coincided with each other and the result of the first measurement I was accurate.

Further, the densities of the foams produced in Examples and Comparative Examples were obtained from the volume and weight of the samples obtained by cutting the foams into predetermined lengths. Further, the thickness of the foamed body was defined as the set value of the distance between the two plates in the molding device described later. Example 1 As a styrene resin, MFR is 5.6 g / 10 min.
Polystyrene having a die swell ratio of 1.95 at a shear rate of 200 s ^{−1 and} a die swell ratio of 2.18 at a shear rate of 600 s ⁻¹ was used.

Then, to 100 parts by weight of this polystyrene,
0.1 parts by weight of pigment, 2.0 parts by weight of talc as a bubble nucleating agent, 2.5 of hexabromocyclododecane as a flame retardant
Parts by weight were added and dry blended. Next, this mixture was mixed with a tandem extruder having a first extruder and a second extruder (caliber: 1st = φ200 mm, 2nd = φ300 m).
m) is supplied to the hopper, is melted and mixed in the first extruder connected to the hopper, and is mixed with butane (a mixture of 60% by weight of n-butane and 40% by weight of i-butane) as a foaming agent and chlorinated. Methyl and was pressed in. The amount of butane press-fitted is
3.0 parts by weight per 100 parts by weight of polystyrene, and the amount of methyl chloride pressed in was 7.
It was 5 parts by weight.

Next, the molten mixture further melted and mixed is continuously supplied from the first extruder to the second extruder and uniformly cooled to a temperature suitable for foaming in the second extruder, 2 The plate was extruded and foamed into a plate shape through a die of a die connected to the tip of the extruder (the lip thickness of the die was 3.5 mm and the lip width was 340 mm). The conditions of the extrusion foaming were a pressure of the die of 5.4 MPa, a resin temperature of 110 ° C., and a discharge rate of the resin per hour of 1300 kg / hour.

The foam extruded and foamed through the die was passed between the two plates of a molding apparatus having two plates attached at the tip of the die and arranged at 100 mm intervals.
By cooling at the same time as molding, thickness 100 mm, width 95
A 0 mm plate-like foam was produced. The obtained foam has a density of 28.4 kg / cm ³ and an average cell diameter φAV of 0.3.
The foamability was 0 mm and the ratio φVD / φAV was 1.1, indicating good foamability. In addition, the heat conductivity (average temperature 20 ° C.) of 60 days after extrusion foaming is 0.0335 W / m · K, which is excellent in heat insulating property, and the residual gas amount of butane is 2.5% of the total amount of the foam.
The flame-retardant property was excellent in flame retardance, since the average value of the flame-extinguishing time was 1.1 seconds.

Example 2 In the same manner as in Example 1 except that the butane press-in amount was 3.5 parts by weight per 100 parts by weight of polystyrene,
A plate-like foam having a thickness of 100 mm and a width of 950 mm was manufactured. The obtained foam has a density of 28.0 kg / cm ³ ,
The average cell diameter φAV was 0.30 mm, and the ratio φVD / φAV was 1.1, indicating good foamability. After extrusion foaming, 60
The thermal conductivity (average temperature 20 ° C) at the time when a day has passed is 0.
It has an excellent heat insulating property at 0325 W / m · K, the residual gas content of butane is 3.3% by weight of the total amount of the foam, and the average extinction time is 2.8 seconds, which is also excellent in flame retardancy. It was

Example 3 A plate-like foam having a thickness of 100 mm and a width of 950 mm was prepared in the same manner as in Example 1 except that 8.0 parts by weight of ethyl chloride was pressed into 100 parts by weight of polystyrene instead of methyl chloride. Manufactured. The resulting foam has a density of 28.3.
kg / cm ³ , average bubble diameter φAV is 0.35 mm, ratio φ
VD / φAV was 1.1, indicating good foamability. In addition, the heat conductivity (average temperature 20 ° C.) of 60 days after extrusion foaming is 0.0339 W / m · K, which is excellent in heat insulation, and the residual gas amount of butane is 2.5% by weight of the total amount of the foam. %so,
Moreover, the average value of the extinction time was 1.8 seconds, and the flame retardancy was excellent.

Example 4 In the same manner as in Example 1 except that the distance between the two plates of the molding apparatus was 80 mm, the thickness was 80 mm and the width was 950 mm.
A plate-shaped foam body was produced. The resulting foam has a density of 2
9.1 kg / cm ³ , average bubble diameter φAV is 0.34 m
m, and the ratio φVD / φAV was 0.9, indicating good foamability. In addition, the thermal conductivity (average temperature 20 ° C) at the time of 60 days after extrusion foaming is 0.0315 W / mK, which is excellent in heat insulation, and the residual gas amount of butane is 2.5% of the total amount of the foam. %, And the average value of the flame-extinguishing time was 1.1 seconds, which was excellent in flame retardancy.

Comparative Example 1 The butane press-in amount was 4.5 parts by weight per 100 parts by weight polystyrene, and the methyl chloride press-in amount was polystyrene 1
A plate-like foam having a thickness of 100 mm and a width of 950 mm was produced in the same manner as in Example 1 except that the amount was 6.5 parts by weight per 00 parts by weight. The obtained foam has a density of 28.0.
kg / cm ³ , average bubble diameter φAV is 0.28 mm, ratio φ
VD / φAV was 1.1, indicating good foamability. The heat conductivity (average temperature 20 ° C.) of 60 days after extrusion foaming was 0.0320 W / m · K, which was excellent in heat insulation. However, the amount of residual gas of butane was 4.0% by weight of the total amount of the foam, and the average value of the extinguishing time was 5.6 seconds, which was a problem in flame retardancy.

Comparative Example 2 As a styrene resin, MFR was 7.0 g / 10 min.
And a polystyrene having a die swell ratio of 1.60 at a shear rate of 200 s ⁻¹ (trade name: Estyrene G-17 manufactured by Nippon Steel Chemical Co., Ltd.) was used, and the amount of methyl chloride injected was polystyrene 100. A thickness of 10 was obtained in the same manner as in Example 1 except that the amount was 7.0 parts by weight.
A plate-like foam having a width of 0 mm and a width of 950 mm was manufactured.

The obtained foam had a density of 28.4 kg /
cm ³ , the average bubble diameter φAV was 0.30 mm,
The ratio φVD / φAV was 1.2, and the bubbles were in the state of rising to VD. After extrusion foaming, the thermal conductivity (average temperature 20 ° C.) at a time point of 60 days was 0.0.
The heat insulation was insufficient at 345 W / m · K. The residual gas amount of butane was 2.5% by weight of the total amount of the foam, and the average flame extinction time was 1.1 seconds, indicating good flame retardancy.

Comparative Example 3 In the same manner as in Example 1 except that the distance between the two plates of the molding apparatus was 110 mm and the amount of methyl chloride pressed in was 7.0 parts by weight per 100 parts by weight of polystyrene. Thus, a plate-like foam having a thickness of 110 mm and a width of 950 mm was manufactured. The obtained foam has a density of 28.0 kg / cm.
³ , the average bubble diameter φAV was 0.34mm, but the ratio φ
VD / φAV was 1.3, and bubbles were in a state of rising to VD. After extrusion foaming, the thermal conductivity (average temperature 20 ° C.) 60 days later was 0.036.
The insulation was insufficient at 0 W / m · K. The residual gas amount of butane was 2.5% by weight of the total amount of the foam, and the average flame extinction time was 1.1 seconds, indicating good flame retardancy.

Comparative Example 4 A plate-like foam having a thickness of 100 mm and a width of 950 mm was produced in the same manner as in Example 1 except that the amount of talc as a cell nucleating agent was reduced to 1.0 part by weight. The obtained foam had a density of 28.4 kg / cm ³ and a ratio φVD / φAV of 0.9, but the average cell diameter φAV was 0.52 mm, and the cells were too large. . The heat conductivity (average temperature 20 ° C.) at a time point of 60 days after extrusion foaming was 0.0365 W / m · K and the heat insulating property was insufficient. The residual gas amount of butane was 2.5% by weight of the total amount of the foam, and the average flame extinction time was 1.1 seconds, indicating good flame retardancy.

The above results are summarized in Tables 1 and 2.

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[Table 1]

[0075]

[Table 2]

[0076]

As described above in detail, according to the present invention, a styrenic resin foam which does not use CFC as a foaming agent and has the same high heat insulation and flame retardancy as the use of CFC. It is possible to provide a body and an efficient manufacturing method thereof.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 25:04 C08L 25:04 F term (reference) 4F074 AA32 AB05 BA35 BA42 CA22 DA03 DA32 4F207 AA13C AB02 AE02 AG01 AG20 AH46 KA01 KA11

Claims (5)

[Claims] 1. A styrenic resin foam formed by extruding and foaming a styrenic resin into a plate using a foaming agent containing at least a hydrocarbon and an alkyl chloride.
(1): φAV = (φMD + φTD + φVD) / 3 (1) [wherein, φMD is the bubble diameter in the extrusion flow direction, φTD is the bubble diameter in the plate width direction, and φVD is the bubble diameter in the plate thickness direction. ] The average bubble diameter φAV obtained by
Ratio of φVD and φAV in the range of 50 mm φVD / φA
V is in the range of formula (2): 0.8 ≦ φVD / φAV <1.2 (2), and the residual amount of hydrocarbons is 3.5% by weight or less of the total amount of the foam. Styrenic resin foam. 2. A melt mass flow rate (MFR) of 4 to.
The styrene-based resin foam according to claim 1, which is formed using a styrene-based resin having a die swell ratio of 1.8 or more at a shear rate of 200 s ⁻¹ at 10 g / 10 min. Wherein extrusion foaming after a thermal conductivity at the time of the lapse of 60 days (average temperature 20 ° C.) is less 0.034W / m · K, and the combustion of the measuring method A defined in JIS A9511 _-1995 The styrene-based resin foam according to claim 1, wherein the average value of the extinction time in the property test is 3 seconds or less. 4. The styrene resin foam according to claim 1, wherein the plate has a thickness of 25 mm or more and less than 110 mm. 5. A method for producing a styrenic resin foam according to claim 1, which comprises a melt mass flow rate (MF).
R) is 4 to 10 g / 10 min and the shear rate is 20.
Styrenic resin foaming, characterized in that a styrene resin having a die swell ratio of 1.8 or more at ^{0 s −1} is extruded and foamed into a plate shape by using a foaming agent containing at least a hydrocarbon and an alkyl chloride. Body manufacturing method.