JPH10306172A - Low-density polystyrene resin foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foam having specified density, thermal dimensional change, compression strength, and thermal conductivity with a good flowability and extrudability without the necessity for a flowability improver by using a polystyrene resin having a specified melt index. SOLUTION: A polystyrene resin foam having a density of 16-23 kg/m<3> is obtd. by extruding a melt mixture contg. a polystyrene resin having a melt index of 0.5-6.5 g/10 min, a blowing agent, and other necessary additives from a high-pressure zone into a low-pressure zone. Thus obtd. foam has thermal dimensional changes in both the length and width directions of 0.6% or lower at 70 deg.C (based on the dimensions before heating) and has a compression strength of 1.0 kg/cm<2> or higher, a thermal conductivity of 0.035 kcal/mh deg.C or lower, and an average cell size of 0.45-2. 5 mm. The melt mixture before extrusion contains an inorg. cell-controlling agent and pref. at least one blowing agent having a solubility parameter different from that of the resin by 2 cal/cc or lower.

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, and more particularly, to a polystyrene resin foam having low density, good extrudability, good dimensional stability and high mechanical strength. About the body.

[0002]

2. Description of the Related Art Conventionally, extruded polystyrene resin foams can be produced continuously and efficiently, and are generally produced by properties such as heat insulation performance, light weight, low water absorption and workability. It is widely used as insulation for houses and other buildings. However, in the extrusion foaming technique, it is difficult to reduce the density due to problems such as compatibility between the resin and the foaming agent, maintenance of the balance between the resin temperature and the resin pressure, and balance between the vapor pressure of the foaming agent and the resin viscosity. Strange Even if the density is reduced, internal foaming, that is, a blowhole is generated in the extruder, and the extruder communicates with the cell structure, resulting in poor heat insulation performance.

[0003] Therefore, a method for producing a so-called bead foam by expanding a polystyrene bead containing a foaming agent, and a method for extruding and then leading to a decompression device (JP-A-59-1984)
Japanese Patent Application Laid-Open Nos. 62122 and 58-63426), and a method of reducing the density by extruding a liquid having a large heat capacity at room temperature with a liquid vapor (Japanese Patent Publication No. 4224071).

[0004] However, bead foam expands foaming particles containing a foaming agent in several steps, and a low-density foam has a large particle size and cannot be air-tightly packed into a molded product. It is difficult to form a foam with low fusion between particles. Since water penetrates into the gaps of the beads, the water resistance is lower than that of the extruded polystyrene foam. Dimensional stability is inferior to extruded expanded polystyrene foam.

[0005] In the method of leading to the decompression device after extrusion, the decompression device itself becomes very large, it is difficult to take action on the foam for controlling the physical properties, and it is difficult to obtain uniform physical properties of the product itself. The sealing property is important on the device, but the sealing method is difficult. Even if the degree of decompression slightly changes due to the sealing performance, it affects the uniformity of physical properties. In other words, there is a problem that variation in time and between lots increases.

[0006] In the method of surrounding with steam having a large heat capacity, it is necessary to consider the material of the device depending on the type of moisture or the vapor of the liquid to be used. Since a period or a process for removing the condensate of the vapor remaining in the foam is required, the cost or heat loss is increased. Depending on the type of steam, the heating temperature, and the amount, the physical properties are not uniform. For example, water vapor has a gas permeation rate for polystyrene of air (N
₂ ) about 4000 times. However, if water vapor is applied too much, the foam becomes too low in density, shrinks at room temperature, and retains condensed water inside the foam,
A method is needed to remove this. In addition, there is a problem that the density reduction ratio of the foam surface layer is large, the density of the surface layer is lower than the density of the center layer, and the physical properties are nonuniform.

In Japanese Patent Publication No. 59-25814,
A method for producing extruded thermoplastic synthetic resin foam with low density and small cell size is described. However, in this publication, a resin having a large melt index is used.
83G according to the method described in US Pat. No. 83G). A cell size of 0.4 obtained by using a polystyrene resin having a melt index value of 6.5 or more as described above.
Low-density foams of 5 mm or less have large dimensional changes due to temperature changes. For this reason, after extrusion molding, after cutting to the desired dimensions, the dimensions will be out of order, so it will be necessary to process again, and after construction, the dimensions will change due to temperature changes, and sufficient heat insulation will occur. Does not perform. In the foaming process, when a low-density foam is obtained by using a polystyrene resin having a melt index of 6.5 or more, since the resin has a low rigidity, bubble breakage is likely to occur, and it is difficult to obtain a good foam. In addition, a melt index value of 6.5
When the above polystyrene resin is used, in order to reduce the density, the gel pressure in the system is reduced due to the mixing of a large amount of the foaming agent, a separation phenomenon of the mixed foaming agent and the resin occurs, internal foaming occurs, and There is a problem that it is difficult to obtain a thick foam.

[0008] In general, a plate-like foam used as a heat insulating material requires considerably high precision in dimensional stability as a product. For example, the dimensional change due to temperature fluctuation is limited to about ± 0.6% in use, and if it changes more than that, after installation, there will be gaps and poor insulation performance, and conversely, if it expands, it will warp, Sufficient heat insulation performance cannot be obtained. Further, when used as a composite product, peeling or warping occurs due to shear stress at an interface with a metal plate, plywood, or mortar concrete that has a small dimensional change due to a temperature difference.
However, with a resin having a melt index of 6.5 or more, when the density of the foam is reduced, the dimensional change due to temperature fluctuation cannot be suppressed to ± 0.6% or less.

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present inventors have developed a thick plate-shaped sheet having a low density (16 kg / m ^{2 to} 23 kg) having good dimensional stability by extrusion foaming. /
m ³ ) As a result of intensive research on a method for producing a polystyrene resin foam, a polystyrene resin having a low melt index value was used, and the difference between the solubility parameter value of the resin and the solubility parameter value of the blowing agent was small. When a foaming agent having good compatibility is mixed with a melt index value of a resin at a certain injection amount, the foaming agent required for lowering the density is low without using a fluidity improver. It was clarified that a polystyrene resin foam having good extrusion moldability and having the above-mentioned properties can be produced because it is uniformly mixed and dispersed with a resin having a melt index value and has an appropriate fluidity. Completed the invention.

Thus, the present invention provides (1) ASTM-D
A polystyrene resin foam using a polystyrene resin having a melt index value of 0.5 to 6.5 g / 10 min as measured by the method described in -1238G, wherein the density of the foam is in the range of 16 to 23 kg / m ³ . The heating and dimensional changes in the length and width directions are within 0.6% of the original dimensions when heated at 70 ° C., and the compressive strength is 1.0 kg / cm ^2.
As described above, a low-density polystyrene resin foam having a thermal conductivity of 0.035 kcal / mh ° C or less is provided.

The following are preferred embodiments of the present invention. (2) Including an inorganic cell regulator. (3) The average cell diameter of the foam is in the range of 0.45 to 2.5 mm. (4) The difference between the solubility parameter (δp) and the solubility parameter (δ _BA ) of the polystyrene resin is 2 (cal / cc) ^1/2
It contains at least one of the following blowing agents.

(5) The density is in the range of 16 to 20 kg / m ² . (6) The melt index value of the polystyrene resin is 1.
It is within the range of 0 to 5.0 g / 10 min. (7) The heating dimensional change is 0.4% or less.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The low-density polystyrene resin foam of the present invention is specifically, but not exclusively, a molten mixture containing a polystyrene resin, a foaming agent and other necessary additives in a high pressure zone. In order to produce a polystyrene resin foam having a density range of 16 to 23 kg / m ³ by extruding into a low pressure zone, 1) ASTM-D-
Using a polystyrene resin having a melt index value in the range of 0.5 to 8.0 (g / 10 min) measured by the method described in 1238G, 2) a solubility parameter (δp) with a solubility parameter (δp) of the polystyrene resin ( δ
_BA ), at least one type of blowing agent having a difference of 2 [(cal / cc) ^1/2 ] or less is used in relation to the melt index value F (g / 10 min) of the polystyrene resin in the following relationship: 1.5-0.038F ≦ M _BA ≦ 3.1-0.038F is injected at an injection amount M _BA (mol / kg of resin),
3) The injection amount W _BA (1 kg of the molar resin) of the total blowing agent including the at least one blowing agent is set within the range of 1.8 <W _BA <4.0, and 4) the molten mixture is extruded with a die and a die. It has been made possible by developing a method of uniformly kneading with a kneading device connected to these.

The details will be described below. The polystyrene resin in the present invention is, for example, styrene, α-methylstyrene, chlorostyrene, dichlorostyrene, dimethylstyrene, t-butylstyrene, homopolymers of styrene derivatives such as vinyltoluene, or two or more Refers to a copolymer comprising a combination of

These polystyrene resins used in the present invention have a melt index value (MI value) measured by the method described in ASTM-D-1238G in the range of 0.5 to 6.5 (g / 10 min). It is necessary to be. The use of such a polystyrene resin increases the dimensional stability and mechanical strength of the product when a low-density thick plate-like foam is obtained, and melts a large amount of a foaming agent. It is extremely important to keep the viscosity of the mixture at a proper level.

A polystyrene tree whose MI value exceeds 6.5.
For fats, low density (23-16 kg / m ^ThreeGet the foam)
If the gel pressure in the system of the extruder, mixer and cooler is large
Separation of the foaming agent and the resin due to the lowering of the foaming agent
Phenomenon occurs, there is a limit of low density change, and bubble film
Thinner and less rigid resin, easily breaks bubbles
Product with very poor mechanical strength and dimensional stability.
You. As mentioned above, the plates commonly used as insulation
Foamed foams have a very high degree of dimensional stability as a product.
Degree is required. For example, dimensional change due to temperature fluctuation
Is limited to about ± 0.6% from general usage results.
If it changes more, after installation, there will be a gap
Poor performance, and conversely, warping when swollen,
Insulating performance cannot be obtained. Also used as a composite product
Metal plate, plywood,
Peeling due to shear stress at the interface with rutal concrete
Occurs or warps. On the other hand, the MI value is less than 0.5
Polystyrene resin has extremely poor fluidity,
Even if a good foaming agent is injected, the viscosity of the molten mixture increases.
In addition, extrudability is very poor and foaming efficiency is poor.
Therefore, the density cannot be reduced. Therefore, the present invention
The polystyrene resin used in the method is 0.5 to 6.5.
It is necessary to have the MI value of Of these, 1-5
Those having an MI value are, in particular, extrudable and obtainable.
Excellent mechanical strength and dimensional stability
And preferred.

In the case of a foaming agent, the solubility parameter δ is determined by using a solvent pocket book (Ohm, 56
As described on page 34 of
It is defined by the following equation. δ = (CED) ^1/2 , C.I. E. FIG. D. = E ₁ / V C.I. E. FIG. D. = Cohesive energy density (cal / cm ³ ) E ₁ = Molar heat of vaporization at boiling point (cal / mol) V = Molar volume (cm ³ / mol) As described above, the calculation is performed based on a method in which the constituent units of the polymer are further subdivided, and the value of the intermolecular attraction constant (δv) of each functional group is assumed to be additive, assuming additivity. Examples of the solubility parameters thus obtained are shown below.

Polystyrene 9.05 (cal / cc) ^1/2 styrene-acrylonitrile copolymer 9.49 (cal / cc) ^1/2 (acrylonitrile / styrene = 5/95) Styrene-methyl methacrylate copolymer 9 1 (cal / cc) ^1/2 (methyl methacrylate / styrene = 10/90)

[0019]

Embedded image

For example, polystyrene has a density D of 1.05 g / cc, a molecular weight M _W = 104, and from Tables 1 and 8 on page 37 of the solvent pocket book, the intermolecular attractive constant is

[0021]

Embedded image

Is 735, the sum of them becomes 896, and the solubility parameter δ is obtained by the following equation.

[0023]

(Equation 1)

In the present invention, the blowing agent used includes a volatile organic blowing agent and a thermal decomposition type chemical blowing agent.
For example, trichloromonofluoromethane, dichlorodifluoromethane, dichloromonofluoromethane, monochlorodifluoromethane, 1,1 ', 2-trichlorotrifluoroethane, 1,2-dichlorotetrafluoroethane, 1-chlorotrifluoroethane, 1-chlorotrifluoroethane Chloro-1,
Examples include 1'-difluoroethane, 1,1'-difluoroethane, offtafluorodichlorobutane, methyl chloride, ethyl chloride, methylene chloride, ethylene chloride, carbon dioxide and the like.

In the present invention, at least one component of the blowing agent used has a difference between the solubility parameter of the blowing agent and the solubility parameter of the resin used of 2.0 [(cal / c).
c) ^1/2] using the following things. Such blowing agents are:
Typically, it is a hydrocarbon or a halogenated hydrocarbon. Specific examples include, for example, when a polystyrene resin (solubility parameter: about 9) is used, trichlorotrifluoroethane, trichloromonofluoromethane, methyl chloride, ethyl chloride, and the like. When such a foaming agent is used, since the compatibility with the resin is good, a large amount of the foaming agent can be injected, so that the foaming agent can be uniformly dispersed and mixed, and the density can be easily reduced. Further, even if a resin having a low melt index value as described above, that is, a high-viscosity resin is used, the blowing agent improves the fluidity of the molten mixture.
Since the proper degree of the molten mixture can be maintained, the moldability is good. Further, since the pressure of the molten mixture can be maintained, there is an effect that a large cross-sectional area of a foam is obtained. Furthermore, since the above-mentioned foaming agent is a volatile organic foaming agent, after molding, it diffuses into the air, loses the plasticizing effect, and improves the dimensional stability of the foam.

In the method of the present invention, such a foaming agent is used as a melt index F [(cal /
cc) ^1/2 ] per 1 kg of resin (1.5-
0.038F) to (3.1-0.038F) mol. When the injection amount is equal to or more than (-0.038F + 3.1) mol per 1 kg of the resin in relation to the melt index value F [(cal / cc) ^1/2 ] of the resin to be used, the viscosity of the molten mixture is increased. As a result, the balance of foaming is lost (surging (waving phenomenon)), causing cell destruction, resulting in a communicating foam. Also, in order to obtain an appropriate gel pressure, the die opening must be narrowed, so that from the heat insulating properties, a generally used thick plate-shaped foam having a thickness of 20 mm or more cannot be obtained. .

On the other hand, when the injection amount is not more than (−0.032 F + 1.5) mol per 1 kg of the resin in relation to the melt index value F of the resin used, the amount of the foaming agent having good compatibility is small. Because the viscosity of the molten mixture is too large, the fluidity is poor, the moldability is very poor,
In addition, the foaming efficiency is deteriorated, and it is difficult to reduce the density. Further, since the amount of the foaming agent having poor compatibility with the resin to be used increases, the foaming agent aggregates and foams inside, and a good foam cannot be obtained.

In the present invention, the injection amount per kg of the resin of the total foaming agent used and containing the above foaming agent is as follows.
It must be in the range of 8 to 4.0 moles. The use of such a large amount of the blowing agent is necessary to increase the vapor pressure of the blowing agent in the molten mixture to obtain a low-density foam. That is, 1.8 kg / kg of polystyrene resin
If the amount is less than mol, the density of the obtained plate-like foam is higher than 23 kg / m ³ , and if it is more than 4.0 mol, the extrudability is very poor, and a good foam cannot be obtained.

A preferred composition of the foaming agent is 60 foaming agents having a difference between the solubility parameter value of the resin used and the solubility parameter value of the foaming agent used of 2 [(cal / cc) ^1/2 ] or less.
90 mol%, the foaming agent difference exceeds 2 (cal / cc) ^1/2 is a mixture of 40 to 10 mol%. When the difference between the solubility parameter value of the resin used and the solubility parameter value of the blowing agent used is 2 or less, and the blowing agent is 90 mol% or more,
That is, when the amount of the foaming agent having an error exceeding 2 is 10 mol% or less, the viscosity of the molten mixture is low even if a resin having a higher viscosity than a commonly used resin is used because of high compatibility with the resin. Extrusion foaming cannot produce a thick plate.
In addition, the resin pressure at the tip of the die (die) required for molding cannot be maintained, and foam breakage occurs during extrusion, making moldability difficult.

Still more preferably, the blowing agent used is
It consists of 60 to 90 mol% of methyl chloride, ethyl chloride or a mixture thereof and 40 to 10 mol% of dichlorodifluoromethane, trichlorotrifluoroethane or a mixture thereof. Since methyl chloride and ethyl chloride have particularly good compatibility with polystyrene resins, even when mixed with a large amount of a foaming agent, internal foaming caused by poor dispersion of the foaming agent does not occur. In addition, since methyl chloride and ethyl chloride have a high gas permeation rate to polystyrene resin, it is easy to dissipate from the inside of the foam to the outside. Is performed, the dimensional stability is good. Dichlorodifluoromethane and trichlorotrifluoroethane, which have lower thermal conductivities than air, have a low gas permeation rate to polystyrene resin, so they are encapsulated in foam cells, lowering the thermal conductivity of the foam and reducing the product's thermal conductivity. Excellent heat insulation. That is, methyl chloride, ethyl chloride, or a mixture thereof is 60 to 90 mol%, and dichlorotrifluoromethane and trichlorotrifluoroethane are 40 to 1 mol%.
In the range of 0 mol%, the extrudability is good, and a foam having excellent dimensional stability and thermal conductivity is obtained.

Furthermore, in the present invention, 16 to 23 kg / m ³
In obtaining a low-density polystyrene resin foam in the range of the above by extrusion, the average cell diameter (cell size) is 0.45 to
It is preferable to adjust the thickness to 2.5 mm. When trying to obtain a low-density polystyrene resin-based foam, as described above, not only regulate the type and amount of the resin and the foaming agent to be used, but it is preferable to adjust the cell size of the extruded foam to the above range. . As the amount of the foaming agent used increases, the cell size generally tends to decrease.However, as the cell size decreases, the thickness of the cell walls becomes thinner, so that the cells become open cells during extrusion and foaming, thereby deteriorating the water vapor permeability and reducing the amount of CFC gas. There are problems such as a decrease in thermal conductivity due to diffusion, a difficulty in obtaining a foam having a large thickness and a large cross-sectional area, and a decrease in dimensional stability due to a decrease in the thickness of a cell wall. . The cell size can be adjusted by the type or composition of the foaming agent to be used and the amount of the foam adjusting agent such as talc. In general, the cell size can be increased as the foaming agent has higher solubility in the resin and the evolution amount of the cell regulator decreases.

In the present invention, more specifically, a molten mixture containing a polystyrene resin, a foaming agent and other necessary additives is mixed in a kneader using a variable speed drive type kneader.
More than a minute, by stirring at a relative speed of the stirring blade of the kneader that satisfies the following formula, the foaming agent is uniformly dissolved and dispersed in the resin, and a low-density and good dimensional stability polystyrene resin foam is obtained. Preferably, it allows for manufacturing.

S ≧ (1100 / D) -23 (where S is the relative speed (m / min) of the stirring blade of the kneader, D
Represents a foam density (kg / m ³ ). Here, a foaming agent having a difference in solubility parameter of 2 or less,
In relation to the melt index value F of the used polystyrene resin, (1.5-0.038
F) to (3.1-0.038F) mol, so that the viscosity of the molten mixture is kept in an appropriate range.
Furthermore, since the foaming temperature is appropriately determined within the range of 110 to 125 ° C., the pressure of the molten mixture is also specified in an appropriate specific range. Therefore, as long as the relationship between the polystyrene resin and the amount of the foaming agent is not limited to the specific foaming agent, by setting the above stirring and temperature conditions, a polystyrene resin foam having low density and good dimensional stability can be obtained. Can be manufactured.

In the present invention, it is preferable to use an inorganic foam adjuster as the foam adjuster. A polystyrene-based low-density foam using a conventional organic foam control agent (for example, indigo) reacts with the organic-based foaming agent and easily dissolves and decomposes. The foaming agent used is limited. On the other hand, since the inorganic foam regulator does not react with the organic foaming agent and dissolves or decomposes, the foaming agent to be used is not limited, and the effect of obtaining a foam having a uniform cell size distribution is obtained. is there. In addition, the use of the inorganic cell regulator makes it possible to separately control the color and cell size of the foam, so that a foam having small variations in color and cell size can be obtained.

Various powders such as talc, kaolin, calcium carbonate, barium sulfate and the like can be used as the inorganic cell regulator in the present invention, but talc is preferred in terms of uniformity of cells and cost. The amount of the additive used is
It can be appropriately selected according to the cell size, but is usually 0.005 to 100 parts by weight of the polystyrene resin.
1.0 part by weight is used.

In the present invention, in addition to the above additives, a flame retardant, an ultraviolet absorber, a lubricant, and a coloring agent are appropriately added as necessary. In the present invention, the blowing agent is supplied into the resin by an injection device before supplying the resin to the extruder or after heating and melting the resin. In the extruder, the resin is melted and extruded into a kneading device. The extruded melt is passed through a kneading device, and the molten mixture is uniformly kneaded. The molten mixture is extruded from the kneading device from a high pressure zone to a low pressure zone by passing through an extrusion die. The extruded extrudate is
It is formed into a plate-shaped formed body having a constant cross-sectional area by a forming device.

Here, the role of the kneading device connected between the extruder and the die is to cut the molten mixture extruded from the extruder and increase the surface area, thereby improving the dispersibility of the foaming agent. Another object of the present invention is to make it possible to uniformly disperse and mix a large amount of a foaming agent necessary for reducing the density. Next, as an example, when a polystyrene resin having a composition of F-12 / MeCl = 2 mol / 8 mol and a melt index value of 3 is used, and the residence time of the molten mixture in the kneader is about 15 minutes, FIG. 1 shows the relationship between the lowest density obtained and the relative speed of the stirring blades of the kneading machine without causing internal foaming when the injection amount of the blowing agent was gradually increased. As the relative speed of the kneading machine is increased, the dispersibility of the foaming agent in the resin is improved, and a large amount of the foaming agent necessary for lowering the density can be injected. Note that this relationship is determined by the above equation S ≧ (1100 / D)
−23.

Kneading capacity of the above-mentioned variable speed drive type kneading apparatus
Is the number of rotations of the rotor, the number of stirring blades, kneading of the molten mixture
Depends on the dwell time in the aircraft. Melting at high temperatures
If the residence time of the mixture in the kneader is too long, the resin will deteriorate.
Required some technical considerations. Only
In the present invention, 1) as a polystyrene resin
Measured by the method described in ASTM-D-1238G
Melt index value is 0.5 to 6.5 (g / 1
0) using a polystyrene resin in the range of 2 min.
Solubility of Tylene Resin with Solubility Parameter (δp)
Parameter (δ _BA) Is 2 [(cal / cc)^1/2〕below
At least one type of blowing agent is
The following relationship between the tilt index value F (g / 10 min) and 1.5-0.038F ≦ M_BAInjection amount M satisfying ≦ 3.1-0.038F_BA(Mol / kg of resin)
And 3) a total blowing agent comprising at least one blowing agent as described above.
Injection amount W_BA(Mol / kg resin) 1.8 <W_BA<4.
By setting it within the range of 0, resin degradation may occur.
It became possible to knead it.

The kneading machine is a variable speed kneading machine as shown in FIG. 2 or a complex mixing machine described in Japanese Patent Application Laid-Open No. 61-69428 and a cylinder containing the same. Such as a mixer that rotates around the plate. Also, the amount of foaming agent dissolved in the resin,
There is a limit, and no matter how much the kneading capacity is increased, bubbles of the foam are destroyed due to poor dispersion, a good foam is not obtained, and power is wasted.

Next, one mode of an experiment using the variable speed type driving kneader shown in FIG. 2 will be described. The variable speed driven kneader used here has a stirring blade 3 on a partially hollow rotor 4 inserted in the center in the longitudinal direction of the molten mixture.
0 rotors are attached in the circumferential direction, and the rotor 4
Are enclosed in a barrel 2. As the rotor 4 rotates, kneading is performed. In FIG. 2, reference numeral 1 denotes a jacket for the refrigerant, and 5 denotes a pipe into which the refrigerant is inserted.

MeCl / F-113 / F-12 = 1.5 mol / 0.5 mol / 0.5 mol (MeCl is methyl chloride, F-1
13, F-12 is a trade name of trichlorotrifluoroethane and dichlorodifluoromethane. In the foaming agent composition of (2), 2.5 mol is injected under pressure per 1 kg of resin, and when the relative speed of the stirring blade of the kneader is 35 m / min and the residence time of the molten mixture in the kneader is 15 minutes, the density is 19 kg / m. A polystyrene foam of ³ was obtained, but MeCl / F-113 / F-12 =
In the case of the foaming agent composition of 1.0 mol / 0.5 mol / 1.0 mol, when the relative speed of the stirring blade of the kneader was 35 m / min, blowholes, that is, internal foaming occurred, and the foam was continuous. However, when the flow rate was set to 40 m / min, a foam having good closed cells was obtained. As described above, when the amount of the foaming agent having poor compatibility was increased, a good foam was obtained by increasing the relative speed of the stirring blade of the kneader, that is, by increasing the kneading capacity. For these reasons, the injection amount of the blowing agent is currently limited to about 4.0 mol per kg of resin.

Although the low-density polystyrene resin foam of the present invention and the preferred method of producing the same have been specifically described above, the present invention has been modified and applied within the scope of the technical idea of the invention described in the claims. Those are also within the scope of the present invention.

[0043]

EXAMPLE 1 The melt index value (MI value) was 1.1 g / 10 min.
100 parts by weight of polystyrene having a solubility parameter value of 9.05 (cal / cc) ^1/2 and 0.1 part by weight of talc as a foam regulator are supplied to a screw extruder having an inner diameter of 90 mmφ at a rate of 500 kg per hour. Further, as a blowing agent, 2 mol of methyl chloride (solubility parameter value = 9.7 (cal / cc) ^1/2 ) and trichlorotrifluoroethane (solubility parameter value =
1 (7.4 (cal / cc) ^1/2 ) and 0.6 mol of dichlorodifluoroethane (solubility parameter value = 6.6 (cal / cc) ^1/2 ) were injected from the blowing agent injection port.

Subsequently, the melt was mixed with a variable speed rotor driven mixer (45) connected between an extruder and a slit die.
m / min), and uniformly extruded the molten mixture from a slit die (width 200 mm × gap 3 mm) at 120 ° C. into the atmosphere by extrusion foaming.
m, formed into a thick plate-like foam having a width of 600 mm. Tables 1 to 4 show the observed extrudability and various physical properties of the test pieces together with various conditions during the production process.

In each table, 1) The MI value of the resin used was measured according to ASTM-D-1238G. 2) The density of the foam is a value measured after standing for 3 days at 20 ° C. after extrusion molding. 3) The average cell size of the foam is ASTM-3576-7
It is a value measured according to 7.

4) The compression strength of the foam is 20 ° C. after extrusion molding.
Is the strength in the thickness direction measured according to JIS A9511 after standing for 5 days. 5) The thermal conductivity of the foam is a value measured according to JIS A 9511 after being left at 20 ° C. for 7 days after extrusion molding. 6) The change in the heating dimension in the length and width directions of the foam was a change from the original dimension when heated to 70 ° C. in an oven after standing at 20 ° C. for 7 days (− indicates shrinkage. And + represents elongation).

7) The cell size distribution of the foam was determined by dividing the foam cross section into three in the thickness direction, measuring the cell size of the outer layer part and the central part in the same manner as in 3), and evaluating the difference from the difference as follows. ○ The difference is 0.05 mm or less △ The difference is 0.05 mm to 0.1 mm × The difference is 0.1 mm or more Examples 2 to 15 and Reference Examples 1 to 18 Mixed foaming agents and melts having the compositions shown in Tables 1 to 4 The procedure was performed in the same manner as in Example 1 except that the amounts of polystyrene, talc and indigo were used as index values.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

In the case of a wooden house, the space between the joists for the evaluation test floor is generally 260 mm for Western-style rooms and 410 mm for Japanese-style rooms. However, due to the construction error of the carpenter, an error of about ± 5 mm occurs in this interval. Therefore, for the foams of Examples 7 to 9 and Reference Examples 14 and 15, a sample having a width 10 mm wider than the joist interval (width 2
70mm x thickness 25mm x length 910mm and width 420mm x thickness 5mm
× length 910 mm).

Table 5 shows the results. In the evaluation, a broken one was evaluated as x, a cracked one was evaluated as △, and a good one was evaluated as ○. From this evaluation test, the density range of 25 kg /
m ³ or less, preferably 22 kg / m ³ or less.

It has also been shown that the foam of the present invention is useful for wooden house applications.

[0055]

According to the present invention, the density range is from 16 to 23.
Despite having a low density of kg / m ³ , a plate-like foam having uniform physical properties in cross section, less color unevenness for each lot, and good dimensional stability is provided, and the plate-like foam is lightweight, Excellent heat insulation, good workability, and excellent secondary workability such as cutting.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the number of rotations of a rotor of a kneading apparatus and a minimum density at which internal foaming does not occur.

FIG. 2 is a cross-sectional view of a variable speed drive-type kneading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Refrigerant jacket 2 ... Cooler 3 ... Blade 4 ... Rotor inserted in the center 5 ... Pipe for inserting a refrigerant

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[Procedure amendment]

[Submission date] May 21, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

These polystyrene resins used in the present invention have a melt index value (MI value) measured by the method described in ASTM-D-1238G in the range of 0.5 to 6.5 (g / 10 min). It is necessary to be. The use of such a polystyrene resin increases the dimensional stability and mechanical strength of the product when a low-density thick plate-like foam is obtained, and melts a large amount of a foaming agent. It is extremely important to keep the viscosity of the mixture at an appropriate level.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

A polystyrene tree whose MI value exceeds 6.5.
For fats, low density (23-16 kg / m ^Three Get the foam)
If the gel pressure in the system of the extruder, mixer and cooler is large
Separation of the foaming agent and the resin due to the lowering of the foaming agent
Phenomenon occurs,Low densityAnd the bubble film is thin
The resin has low rigidity and is liable to break bubbles.
Product with very poor mechanical strength and dimensional stability.
You. As mentioned above, the plates commonly used as insulation
Foamed foams have a very high degree of dimensional stability as a product.
Degree is required. For example, dimensional change due to temperature fluctuation
Is limited to about ± 0.6% from general usage results.
If it changes more, after installation, there will be a gap
Poor performance, and conversely, warping when swollen,
Insulating performance cannot be obtained. Also used as a composite product
Metal plate, plywood,
Peeling due to shear stress at the interface with rutal concrete
Occurs or warps. On the other hand, the MI value is less than 0.5
Polystyrene resin has extremely poor fluidity,
Even if a good foaming agent is injected, the viscosity of the molten mixture increases.
In addition, extrudability is very poor and foaming efficiency is poor.
Therefore, the density cannot be reduced. Therefore, the present invention
The polystyrene resin used in the method is 0.5 to 6.5.
It is necessary to have the MI value of Of these, 1-5
Those having an MI value are, in particular, extrudable and obtainable.
Excellent mechanical strength and dimensional stability
And preferred.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

Still more preferably, the blowing agent used is
It consists of 60 to 90 mol% of methyl chloride, ethyl chloride or a mixture thereof and 40 to 10 mol% of dichlorodifluoromethane, trichlorotrifluoroethane or a mixture thereof. Since methyl chloride and ethyl chloride have particularly good compatibility with polystyrene resins, even when mixed with a large amount of a foaming agent, internal foaming caused by poor dispersion of the foaming agent does not occur. In addition, since methyl chloride and ethyl chloride have a high gas permeation rate with respect to the polystyrene resin, it is easy to disperse from the inside of the foam to the outside. Is performed, the dimensional stability is good. Dichlorodifluoromethane and trichlorotrifluoroethane, which have lower thermal conductivity than air, have a low gas permeation rate through polystyrene resin and are therefore enclosed in foam cells, lowering the thermal conductivity of the foam and insulating the product. And excellent properties. That is, methyl chloride, ethyl chloride, or a mixture thereof is 60 to 90 mol%, and dichlorotrifluoromethane and trichlorotrifluoroethane are 40 to 10 mol%.
In the range of mol%, extrudability is good, dimensional stability,
It becomes a foam having excellent thermal conductivity.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

Furthermore, in the present invention, 16 to 23 kg / m ³
In obtaining a low-density polystyrene resin foam in the range of the above by extrusion, the average cell diameter (cell size) is 0.45 to
It is preferable to adjust the thickness to 2.5 mm. When trying to obtain a low-density polystyrene resin foam , as described above, not only the type and amount of the resin and the foaming agent used but also the cell size of the extruded foam may be adjusted to the above range. As the amount of the foaming agent used increases, the cell size generally tends to decrease.However, as the cell size decreases, the thickness of the cell walls becomes thinner, so that the cells become open cells during extrusion and foaming, thereby deteriorating the water vapor permeability and reducing the amount of CFC gas. There are problems such as a decrease in thermal conductivity due to diffusion, a difficulty in obtaining a foam having a large thickness and a large cross-sectional area, and a decrease in dimensional stability due to a decrease in the thickness of a cell wall. . The cell size can be adjusted by the type or composition of the foaming agent to be used and the amount of the foam adjusting agent such as talc. In general, the cell size can be increased as the foaming agent has higher solubility in the resin and the evolution amount of the cell regulator decreases.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

In the present invention, it is preferable to use an inorganic foam adjuster as the foam adjuster. Low-density polystyrene using conventional organic foam control agents (eg Indigo)
Since the foam reacts with the organic foaming agent and easily dissolves and decomposes, in order to make a uniform cell size distribution,
The foaming agent used is limited. On the other hand, since the inorganic foam regulator does not react with the organic foaming agent and dissolves or decomposes, the foaming agent to be used is not limited, and the effect of obtaining a foam having a uniform cell size distribution is obtained. is there. Also,
The use of the inorganic cell regulator enables the color and cell size of the foam to be controlled separately, so that a foam having a small variation in color and cell size can be obtained.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

Various powders such as talc, kaolin, calcium carbonate, barium sulfate and the like can be used as the inorganic cell regulator in the present invention, but talc is preferred in terms of uniformity of cells and cost. The amount of the additive used is
In accordance with the cell size can be suitably selected, usually, poly
0.005 to 1 with respect to 100 parts by weight of the styrene resin .
0 parts by weight are used.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

The kneading capacity of the above-mentioned variable speed drive type kneading apparatus depends on the number of rotations of the rotor, the number of stirring blades, and the residence time of the molten mixture in the kneader. For this reason, if the residence time of the molten mixture in the kneader at a high temperature is too long, the resin deteriorates, so that some technical considerations are required. In However the present invention, 1) A as polystyrene resin
The melt index value measured by the method described in STM-D-1238G is 0.5 to 6.5 (g / 10
2) at least one type of foam having a solubility parameter (δ _BA ) difference of 2 [(cal / cc) ^1/2 ] or less from the solubility parameter (δp) of the polystyrene resin. The injection amount M _BA (mol / kg resin) satisfying the following relationship 1.5-0.038F ≦ M _BA ≦ 3.1-0.038F with the melt index value F (g / 10 min) of the polystyrene resin. And 3) the injection amount W _BA (mol / kg of resin) of the total blowing agent including the at least one blowing agent is 1.8 <W _BA <4.
By setting the value within the range of 0, kneading can be performed without causing deterioration of the resin.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0052

[Correction method] Change

[Correction contents]

In the case of a wooden house, the space between the joists for the evaluation test floor is generally 260 mm for Western-style rooms and 410 mm for Japanese-style rooms. However, due to the construction error of the carpenter, an error of about ± 5 mm occurs in this interval. Therefore, for the foams of Examples 7 to 9 and Reference Examples 14 and 15, a sample having a width 10 mm wider than the joist interval (width 2
70mm x thickness 25mm x length 910mm and width 420mm x thickness 25
mm × length 910 mm).

Claims (7)

[Claims] 1. A melt index value measured by a method described in ASTM-D-1238G of 0.5 to 0.5.
It is a polystyrene resin foam using a polystyrene resin of 6.5 g / 10 min, and the density of the foam is 16 to 23.
kg / m ³ , the heating and dimensional changes in the length and width directions are within 0.6% of the original dimensions when heated at 70 ° C., and the compressive strength is 1.0 kg / cm ² or more. A low-density polystyrene resin foam having a thermal conductivity of not more than 0.035 kcal / mh ° C. 2. The low-density polystyrene resin foam according to claim 1, further comprising an inorganic cell regulator. 3. The foam according to claim 1, wherein said foam has an average cell diameter of 0.45 to 0.45.
The low-density polystyrene resin foam according to claim 1 or 2, which is within a range of 2.5 mm. 4. The difference between a solubility parameter (δp) and a solubility parameter (δ _BA ) of a polystyrene resin is 2 (cal).
/ Cc) ^1/2 or less of low density polystyrene resin foam according to claim 1, 2 or 3 comprising at least one blowing agent. 5. The low-density polystyrene resin foam according to claim 1, wherein the density is in the range of 16 to 20 kg / m ² . 6. The low-density polystyrene resin foam according to claim 1, wherein the melt index value of the polystyrene resin is in the range of 1.0 to 5.0 g / 10 min. 7. The low-density polystyrene foam according to claim 1, wherein the dimensional change upon heating is 0.4% or less.