JP3523981B2 - Polystyrene resin foam and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polystyrene resin foam and a method for producing the same. More specifically, the present invention relates to a polystyrene resin foam having a large thickness and a low density, which is produced by extrusion foaming using an environment-friendly foaming agent that does not destroy the ozone layer, and a method for producing the same.

[0002]

2. Description of the Related Art At present, a foaming agent used for a plate-shaped polystyrene-based resin foam is, for example, Japanese Patent Publication No. 57-717.
5, a mixed system of methyl chloride (hereinafter abbreviated as MC) or ethyl chloride (hereinafter abbreviated as EC) and 1,1-monochloro-1,1-difluoroethane (F-142b) It has been known. F-1
42b has low thermal conductivity, low combustibility, and remains in the foam for a long period of time, and is therefore preferably used for a plate-shaped styrene resin foam.

However, since F-142b destroys the ozone layer, the total amount of F-142b was regulated from 1996 in a previous Montreal resolution at the United Nations Environment Conference, and 2020
In the year it was decided to abolish its use. Therefore,
It is necessary to develop a foaming agent to replace F-142b. When considering the substitution of F-142b as the foaming agent, hydrocarbon-based foaming agents such as 1,1,1,2-tetrafluoroethane (F-134a), propane and butane are conceivable in consideration of cost. For example, Tokuhyo Hira 2-50365
JP-A-7-165970 describes a foam using F-134a and propane, and JP-A-7-165970 describes a foam using a mixture of F-134a and butane.

[0004]

[Problems to be Solved by the Invention] However, propane,
When a hydrocarbon-based foaming agent such as butane was used for foaming by itself, internal foaming occurred in the foam, and a good foam could not be obtained. Further, increasing the contents of propane and butane has been considered difficult because of the risk of ignition. Further, although F-134a itself has a low thermal conductivity, it has poor compatibility with polystyrene and cannot be left in a large amount in the foam.

Further, in the case of butane and F-134a, a foam having a low density and a low thermal conductivity could be obtained, but the flammability defined in JIS A9511 could not be satisfied. When it was tried to reduce the butane ratio to satisfy the combustibility, internal foaming occurred and a good foam could not be obtained. Meanwhile, propane and F-134
In the case of a, if the ratio of propane is increased, a foam having low thermal conductivity cannot be obtained, and if the ratio of propane is decreased,
Internal foaming occurred and a good foam could not be obtained.

Therefore, the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide propane, butane and F-, which have an ozone depletion potential (ODP) of zero, as a blowing agent.
A polystyrene foam using a foaming agent consisting of 134a and a method for producing the same. Another object of the present invention is 0.035 g / cm ³ foamed to a high ratio by mixing and extruding a foaming agent composed of propane, butane and F-134a using a mixer having a good kneading property such as a pin mixer. The following low-density polystyrene-based resin foam and a method for producing the same are provided.

Another object of the present invention is to provide a polystyrene resin foam having a low density and a large thickness of 10 to 150 mm, and a method for producing the same. Further, another object of the present invention is to provide a flame retardant polystyrene resin foam having a low thermal conductivity and a method for producing the same.

Thus, according to the present invention, 60 to 10% by weight of propane and 40 to 90 butane are added to the polystyrene resin.
35% to 95 % by weight of the mixture, 1,1,1,2
-A polystyrene resin foam characterized by comprising a polystyrene resin foam obtained by extrusion foaming using a foaming agent comprising tetrafluoroethane in an amount of 65 to 5% by weight.

Further, according to the present invention, 60 to 10% by weight of propane and 40 to 90 % by weight of butane are added to the styrene resin.
% Mixture of 35 to 95 wt% and 1,1,1,2-tetrafluoroethane of 65 to 5 wt% are mixed and extruded to produce a polystyrene resin foam. A method for producing a polystyrene-based resin foam, which is characterized by the above.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION One of the features of the present invention is that the blowing agent contains three components of propane, butane and F-134a. The inventors of the present invention have surprisingly found that a foaming agent having a low density, a low thermal conductivity and a combustibility defined in JIS A9511 can be obtained by the foaming agent comprising the three components of the present invention. ing.

Polystyrene resins usable in the present invention include styrene, methylstyrene, ethylstyrene,
Homopolymers of styrene monomers such as isopropylstyrene, dimethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, and vinylxylene, or acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, acrylic acid esters (for example, methyl, ethyl Etc.), methacrylic acid esters (for example, esters with methyl, ethyl, etc.), and copolymers with vinyl monomers such as maleic anhydride and butadiene. Specifically, polystyrene resin, styrene-maleic anhydride copolymer, styrene-acrylic acid copolymer, styrene-
Acrylic ester copolymer, high impact styrene resin (HIPS), styrene-acrylonitrile copolymer,
Examples thereof include acrylonitrile-butadiene-styrene terpolymer.

The polystyrene resin is 35 to 95% by weight of a mixture of propane and butane, and 65 to 65 of F-134a.
5% by weight and mixed with a blowing agent. When the mixture of propane and butane is less than 35% by weight and the content of F-134a is more than 65% by weight, internal bubbles are generated and a good foam cannot be obtained, which is not preferable. More than 95% by weight of a mixture of propane and butane and 5% of F-134a.
If it is less than wt%, a foam having a low thermal conductivity cannot be obtained, which is not preferable. 40 to 90% by weight of the mixture of propane and butane and 60 to 90% of F-134a.
More preferably, it is 10% by weight.

The above foaming agent is usually mixed in an amount of 5 to 15 parts by weight with respect to 100 parts by weight of the styrene resin in order to reduce the density. Further, the mixture of propane and butane is preferably such that propane is mixed in the proportion of 60 to 10% by weight and butane is mixed in the proportion of 40 to 90% by weight. By using a mixture of propane and butane in this ratio, a foam having a low density, a low thermal conductivity and a combustibility defined in JIS A9511 can be obtained. Butane is n-butane,
It may be i-butane or a mixture thereof. In this mixture, if propane exceeds 60% by weight, internal foaming easily occurs and a low-density foam cannot be obtained, and if butane exceeds 90% by weight, the flame retardancy specified in JIS A9511 cannot be obtained. .

Other foaming agents may be added as long as the effects of the present invention are not impaired. Examples of the other foaming agents include inorganic gases such as carbon dioxide gas, nitrogen gas and oxygen gas, organic gases such as methane, ethane and heptane, water and the like. Further, as a plasticizer, ethers such as dimethyl ether, ethyl methyl ether and ethyl ether may be mixed within 5% by weight of the resin. These plasticizers also have a function as a foaming agent.

Further, an antistatic agent such as SMG (stearic acid monoglyceride) may be added. Next, the polystyrene resin and the foaming agent are mixed. As a mixing method,
There is no particular limitation, and any known method can be used. For example, at a temperature of 180 to 300 ° C, a pin mixer, a dullage, a cavity
A method of mixing with a transfer mixer or the like may be used. In addition, it is preferable to perform the mixing sufficiently. If the mixing is not sufficient, the foaming agent may cause internal foaming to generate voids.

The mixed resin and foaming agent are extruded from a die provided at the tip of the extruder to form a polystyrene resin foam. The pressure (die pressure) of the tip of the die at the time of extrusion is 30 to 70 kg /
It is preferably cm ² . The polystyrene-based resin foam obtained by the above method has 0.024 to 0.035 g.
It has a density of / cm ³ . Density is 0.024g / cm ³
Smaller ones are difficult to manufacture.

Further, the polystyrene resin foam of the present invention is 0.1 to 1.0 mm (more preferably 0.2 to 0.
It is preferable to have an average cell diameter of 6 mm). If the average cell diameter is smaller than 0.1 mm, the thermal conductivity increases and the density increases, which is not preferable. Average bubble diameter is 1.0 mm
If it is larger, the thermal conductivity increases, which is not preferable.

The polystyrene resin foam of the present invention has a thermal conductivity of 0.022 to 0.02 after 2 months from the production.
It can be 29 kcal / m · hour · ° C. When the thermal conductivity is higher than 0.029 kcal / m · hour · ° C, it is not preferable for use as a heat insulating material. Here, manufacturing time 2
The thermal conductivity after months is measured according to JIS A1412. That is, the thickness of the foam after manufacturing for 2 months is 25
mm, length × width = 200 mm × 200 mm as a test piece, the heat flow rate passing through this test piece is measured by using a two-plate flat-plate heat flow meter, and the temperature difference of the test piece at that time is measured.
The value obtained from the obtained heat flow rate and temperature difference is defined as the thermal conductivity specified in the present invention. The inventors of the present invention
It has been found that the thermal conductivity after a lapse of months becomes almost constant.

Further, the polystyrene resin foam is JI
It is preferable that the flammability specified in S A9511 is satisfied. If this flammability cannot be achieved as it is, it may be achieved by adding a flame retardant. Specifically, flame retardants such as hexabromocyclododecane and tetrabromobisphenol A are added in a relatively small amount of 1 to 3% by weight, and the residual gas amounts of propane and butane are set to 3.5 respectively.
It can be achieved by adjusting the amount to be not more than 2.0% by weight.

The method of measuring flammability specified in JIS A9511 is briefly described below. First, five test pieces having a thickness of about 10 mm, a length of about 200 mm and a width of about 25 mm are prepared. The individual test pieces are fixed and the flame is applied at a constant velocity from one end of the test piece to any point. After reaching an arbitrary point, the flame is removed, and the time from that moment until the flame extinguishes is measured, and the average value of the time of 5 sample pieces is taken. This average value means flammability. Note that satisfying the flammability specified in JIS A9511 means that the average value is within 3 seconds.

In addition, the polystyrene resin foam is 10
It can be manufactured as a plate-shaped foam having a thickness of 150 mm (more preferably 25 to 100 mm). Thickness is 10
If it is thinner, the density cannot be lowered. Thickness is 15
If it is thicker than 0 mm, manufacturing becomes difficult. The polystyrene resin foam obtained by the present invention makes use of the characteristics of low density, flammability, and excellent heat insulating property, for roof outer insulation, for tatami, for walls, for dirt, for roofs, for foundations. It can be suitably used as a heat insulating material when building a building.

[0022]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In the examples, “part” means part by weight.

Example 1 100 parts of polystyrene (G-10 manufactured by Nippon Steel Chemical Co., Ltd.) was used as a polystyrene resin, 0.5 part of talc powder was added as a foam nucleating agent, and monoglyceride stearate (SMG) was used as an antistatic agent. 0.06 parts and 3.0 parts of hexabromocyclodecane (HBCD) as a flame retardant were added, and this mixture was supplied to the extruder. A tandem type extruder was used. This mixture was melt-kneaded in an extruder and propane / butane (normal 70%,
Iso30%) / F-134a = 50/40/10 (wt%), and 5.8 parts was press-fitted. After the gas injection, kneading with a screw and further in a cylinder forming a molten resin passage is performed as shown in FIG.
(A) is a schematic side view of the cutout portion, and FIG. 1 (b) is a schematic cross-sectional view], which is a pin mixer 1 in which 52 rows of eight pins 2 are provided in the circumferential direction in the longitudinal direction, Temperature 20
0 ° C, rotation speed 60 rpm, mixing pressure 180 kg / cm ²
Then, the foaming agent and the polystyrene-based resin were well kneaded and then cooled to a foaming-appropriate resin temperature of 130 ° C. by a second extruder. These mixtures were extruded at a rate of 40 kg per hour from a slit-shaped die (lip: W = 50 mm, t = 1.2 mm) attached to the tip of the extruder. The extruded foam was molded by passing it through a molding tool in which two plates closely attached to the tip of the die were made to face each other and cooling at the same time as shaping. This gives a width of 174 mm and a thickness of 32 mm
A plate-like foam of was obtained. The obtained foam had a density of 0.0298 g / cm ³ , a flammability measurement result specified in JIS A9511 of 2.1 seconds, and an average cell diameter of 0.32 mm. In addition, the residual gas amount in the foam body 2 months after production (hereinafter, simply referred to as the residual gas amount in the foam body) is 0.92% by weight of propane, 0.78% by weight of butane, 0.46% by weight of F-134a. Met. Furthermore, the thermal conductivity after 2 months is 0.0283 kcal / m ・ hour ・ ° C.
Met.

Example 2 With the same composition, extruder and die as in Example 1, propane / butane / F-134a = 10/80/10 as a foaming agent.
(Wt%) was press-fitted to 6.7 parts to foam. As a result, a plate-like foam having a width of 171 mm and a thickness of 33 mm was obtained.
The obtained foam had a density of 0.0295 g / cm ³ , a flammability measurement result specified in JIS A9511 of 2.8 seconds, and an average cell diameter of 0.36 mm.
The residual gas content in the foam was 0.20% by weight of propane, 1.65% by weight of butane, and 0.50% by weight of F-134a. Furthermore, the thermal conductivity after 2 months has elapsed is 0.027.
It was 8 kcal / m · hour · ° C.

Example 3 With the same formulation, extruder and die as in Example 1, propane / butane / F-134a = 20/20/60 as a foaming agent.
6.8 parts of (wt%) was press-fitted to foam. As a result, a plate-like foam having a width of 183 mm and a thickness of 28 mm was obtained.
The obtained foam had a density of 0.0334 g / cm ³ , a flammability measurement result specified in JIS A9511 of 1.2 seconds, and an average cell diameter of 0.20 mm.
The residual gas amount is 0.89% by weight of propane and 1.15 of butane.
% By weight, and 2.87% by weight in F-134a. Furthermore,
The thermal conductivity after 2 months was 0.0230 kcal / m · hour · ° C.

Example 4 Propane / butane / F-134a = 5/35/60 (wt%) as a foaming agent was pressed into 7.2 parts with the same composition, extruder and die as in Example 1 to foam. It was Width 1
A plate-like foam having a thickness of 80 mm and a thickness of 29 mm was obtained. The resulting foam has a density of 0.0328 g / cm ³ ,
The flammability measurement results specified in JIS A9511 are 1.
It was 5 seconds, and the average bubble diameter was 0.22 mm. The residual gas amount was 0.20% by weight of propane, 1.43% by weight of butane, and 2.96% by weight of F-134a. Furthermore, the thermal conductivity after 2 months is 0.0228 kcal / m ・ hour ・ ° C.
Met.

Example 5 With the same composition, extruder and die as in Example 1, 5.2 parts of propane / butane / F-134a = 50/45/5 (% by weight) as a foaming agent was pressed and foamed. It was The obtained foam has a thermal conductivity of 0.0302 kcal / m for 2 months.
・ It was ℃.

Example 6 Using the same composition, extruder and die as in Example 1, 5.5 parts of propane / butane / F-134a = 10/85/5 (% by weight) as a foaming agent was pressed and foamed. It was The obtained foam has a thermal conductivity of 0.0305 kcal / m for 2 months.
・ It was ℃.

Comparative Example 1 The same composition, extruder and die as in Example 1 were used, and propane / butane / F-134a = 15/15/70 as a foaming agent.
Although 6.5 parts by weight of (wt%) was pressed in to foam, internal foaming occurred due to insufficient pressure at the die at that time, and a good foam could not be obtained.

Comparative Example 2 6.8 parts of propane / butane / F-134a = 5/25/70 (% by weight) as a foaming agent was pressed and foamed using the same composition, extruder and die as in Example 1. However, at that time, due to insufficient mouthpiece pressure, internal foaming occurred, and a good foam could not be obtained.

Comparative Example 3 With the same composition, extruder and die as in Example 1, butane / F-134a = 40/60 (% by weight) as a foaming agent was used in 6.4.
It was press-fitted and foamed. The obtained foam is JIS A
The measurement result of flammability specified in 9511 is 12 seconds,
It did not show a satisfactory flammability.

COMPARATIVE EXAMPLE 4 Propane / F-134a = 40/60 (% by weight) was used as a foaming agent in the same composition, extruder and die as in Example 1.
Although 8 parts were press-fitted to foam, internal foaming occurred at that time due to insufficient mouthpiece pressure, and a good foam could not be obtained.

The above Examples 1 to 6 and Comparative Examples 1 to 4
Table 1 shows the amount of the foaming agent used and the properties of the foam.

[0034]

[Table 1]

[0035]

The polystyrene resin foam of the present invention is
Add 3 parts of a mixture of propane and butane to polystyrene resin.
It is characterized by comprising a polystyrene-based resin foam obtained by extrusion foaming using a foaming agent composed of 5 to 95% by weight and F-134a of 65 to 5% by weight.

Therefore, F-1 which destroys the conventional ozone layer
F-142 without using a foaming agent consisting of 42b
It is possible to form a polystyrene-based resin foam having the same quality as the foaming agent consisting of b. In addition, the present invention uses a foaming agent composed of propane, butane, and F-134a. Although this foaming agent has poor compatibility with polystyrene-based resins, by using a mixing device such as a pin mixer,
It is possible to produce a polystyrene-based resin foam having a high density, a low density and a large thickness.

Further, the polystyrene resin foam of the present invention has a flammability suitable for use in building materials, etc., in the flammability test by only reducing the residual gas amount of propane and butane and adding a small amount of a flame retardant. Can be given. Also,
The polystyrene-based resin foam of the present invention has a thermal conductivity of 0.029 kcal / two months after the lapse of time by reducing the cell diameter and increasing the residual gas amount of F-134a.
Since it can be set to m · hour or less, it can be used for applications requiring heat insulation.

Furthermore, the present invention is a foam which is excellent in hygiene and safety and a method for producing the same, since it is not necessary to mix conventionally used methyl chloride and ethyl chloride.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a pin mixer used in an example and a schematic side view of a cutout portion.

[Explanation of symbols]

1 pin mixer 2 pin

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08J 9/14 C08L 25/00-25/18

Claims (5)

(57) [Claims] 1. A styrene resin containing 60 to 60 parts of propane .
A mixture of 10 wt.% And butane 40-90 wt .
It is characterized by comprising a polystyrene resin foam obtained by extrusion foaming using a foaming agent consisting of 95% by weight and 1,1,1,2-tetrafluoroethane of 65 to 5% by weight. Polystyrene resin foam. 2. The polystyrene resin foam is 0.02
The foam according to claim 1, which has a density of ^{4 to} 0.035 g / cm ³ . 3. The polystyrene-based resin foam comprises 10 to 1
Claim is a plate-like foam having a thickness of 50 mm 1 also
Is a foam of 2 . 4. The polystyrene resin foam is 0.02
The foam according to any one of claims 1 to 4 , which has a thermal conductivity of 2 to 0.029 kcal / m · hour after 2 months in time and satisfies the combustibility defined in JIS A9511 in the presence of a flame retardant. . 5. A styrene resin and propane 60 to 10
A mixture of 40 % to 90% by weight of butane and 35 to 95 % by weight.
6% by weight of 1,1,1,2-tetrafluoroethane
A method for producing a polystyrene-based resin foam, which comprises producing a polystyrene-based resin foam by mixing a foaming agent of 5 to 5% by weight and extruding and foaming.