JP3733261B2 - Method for producing styrene resin foam - Google Patents

Description

つぎにこの混合物を、第１および第２の２台の押出機が、ピンミキサーを挟んで連結されたタンデム押出機の、第１押出機のホッパーに供給し、当該第１押出機内で、混合温度２００℃で溶融、混合したのち、この第１押出機の途中に設けた２つのノズルから、それぞれ第１押出機内に、発泡剤としての二酸化炭素と、発泡剤としての水に相溶化剤としてのポリオキシエチレンラウリルエーテル（ＨＬＢ＝１６）を溶解した溶液とを圧入、添加した。
【００５０】
上記各成分の添加量は、それぞれポリスチレン１００重量部あたり、二酸化炭素が３．８重量部、水が１．５重量部、ポリオキシエチレンラウリルエーテルが０．３重量部であった。
つぎに、圧入後の溶融混合物を引き続き、第１押出機内でしばらく溶融、混合したのちピンミキサーに連続的に供給し、当該ピンミキサー内で、混合温度１８０℃、混合圧力２００ｋｇ／ｃｍ²、回転速度６０ｒｐｍの条件でさらに十分に溶融、混合した。
【００５１】
そしてこの溶融混合物を、ピンミキサーから第２押出機に連続的に供給し、当該第２押出機内で、押出発泡に適した温度である１３０℃まで均一に冷却したのち、この第２押出機の先端に接続した、リップ幅Ｗ＝５０ｍｍ、厚みｔ＝１．４ｍｍのスリット状の金型を通して大気中に連続的に押し出して発泡させるとともに、３０ｍｍの間隔に配置した一対の板状の成形具間を通して、その厚みが上記成形具の間隔と同じ３０ｍｍになるように矯正しつつ冷却してスチレン系樹脂発泡体を製造した。
【００５２】
得られた発泡体の密度は０．０３０ｇ／ｃｍ³、平均気泡径は０．６ｍｍであった。
実施例２
相溶化剤として、ＨＬＢが１２．６であるポリオキシエチレンラウリルエーテル０．３重量部を使用したこと以外は実施例１と同様にして、厚み３０ｍｍのスチレン系樹脂発泡体を製造した。
【００５３】
得られた発泡体の密度は０．０３２ｇ／ｃｍ³、平均気泡径は０．５ｍｍであった。
比較例１
相溶化剤としてのノニオン系界面活性剤を加えなかったこと以外は実施例１と同様にして、スチレン系樹脂発泡体を製造しようとしたが、内部発泡が発生して、内部構造の均一な発泡体を得ることはできなかった。
【００５４】
比較例２
相溶化剤として、ＨＬＢが９．０であるポリオキシエチレンオクチルフェニルエーテル０．３重量部を使用したこと以外は実施例１と同様にして、スチレン系樹脂発泡体を製造しようとしたが、内部発泡が発生して、やはり内部構造の均一な発泡体を得ることはできなかった。
【００５５】
以上の結果を表１にまとめる。
【００５６】
【表１】

【００５７】
【発明の効果】
以上、詳述したように本発明によれば、炭化水素類やハロゲン化炭化水素類に比べて安全性が高くかつ環境にやさしい、二酸化炭素と水とを発泡剤として使用して、なおかつ炭化水素類などを使用した場合と同程度に低密度、厚肉で、しかも発泡構造も均一な、新規なスチレン系樹脂発泡体を製造することが可能となる。
【図面の簡単な説明】
【図１】本発明の製造方法を実施するための押出機の一例を示す概略図である。
【図２】同図(a)(b)はともに、上記押出機に使用される金型の一例を示す断面図である。[0001]
BACKGROUND OF THE INVENTION
  The present invention has a low density, that is, a high expansion ratio, and a thick styrene resin foam.the body'sManufacturing methodTo the lawIt is related.
[0002]
[Prior art]
Using an extruder, a foamed styrene-based resin is produced by a so-called extrusion foaming method in which a foaming agent is pressed into a heat-melted styrene-based resin and extruded through the die portion of the mold into the atmosphere and foamed. In this case, as the blowing agent, hydrocarbons such as butane and propane, or halogenated hydrocarbons such as methyl chloride, ethyl chloride, and 1-monochloro-difluoroethane are generally used.
[0003]
All of these foaming agents have good compatibility with styrenic resins and are uniformly and heavily impregnated in the resin, so the density is approximately 0.050 g / cm.^ThreeA thick foam having a low density, a high expansion ratio, and a thickness of 10 mm or more can be easily produced by the extrusion foam molding method.
However, among the foaming agents, hydrocarbons have a problem that they are difficult to handle because they are flammable. Some halogenated hydrocarbons also affect the ozone layer.
[0004]
Therefore, use of a gas such as nitrogen or carbon dioxide as a so-called environment-friendly foaming agent that is safe because it does not have flammability and has no risk of affecting the environment has been studied.
However, among the above, nitrogen has a remarkably low compatibility with styrenic resins and cannot be impregnated uniformly and in large quantities in the resin, so that the foam has a low density and a sufficient thickness as in the conventional product. It is virtually impossible to extrude foam.
[0005]
In other words, using nitrogen as a foaming agent to increase the expansion ratio of the foam produced by the extrusion foaming method and lower the density, the pressure inside the extruder is increased to force nitrogen into the resin. It is conceivable to impregnate.
However, in order to obtain a low-density and thick-walled foam like the conventional product by this method, even at the die portion of the extruder, an extremely high pressure that cannot be obtained with the current extruder In order to achieve this, it is necessary to develop from a special extruder capable of generating such high pressure, so that it is difficult to put it into practical use at present.
[0006]
On the other hand, carbon dioxide has better compatibility with styrenic resins than nitrogen, but its value is still insufficient when compared with hydrocarbons, etc. Thick foam cannot be extrusion-foamed. Therefore, it is conceivable to increase the amount of carbon dioxide injected into the resin. However, in this method, as the amount of carbon dioxide increases, the bubbles in the foam become finer and the strength of the film constituting the bubbles decreases. For this reason, heat shrinkage is likely to occur during extrusion, and the degree of hindering the reduction in density and thickness of the foam increases.
[0007]
For this reason, the effect of this method is limited, and it is difficult to produce a foam having a low density and a sufficient thickness as in the conventional product.
[0008]
[Problems to be solved by the invention]
The inventors studied to obtain a low-density, high-foaming ratio and thick-walled foam by using water in combination with the above-described system using carbon dioxide as a foaming agent.
That is, water has a high foaming power when used as a foaming agent for a resin, and has a feature that it can quickly cool a foamed body immediately after foaming and suppress its thermal shrinkage. By using the high foaming power of the foam to prevent the bubbles from becoming too fine, the latter cooling effect can be used to quickly cool the foam immediately after foaming to suppress thermal shrinkage. He thought that by adjusting the amount of carbon and water, a low-density and thick-walled foam could be produced.
[0009]
However, in a temperature range of 150 ° C. or less, which is considered to be optimal for extrusion foam molding of styrene resin, water has a remarkably low dispersibility with respect to styrene resin and the like. When added in an amount that can be exhibited, it is clear that the foam structure becomes non-uniform due to water dispersion unevenness and internal foaming occurs, making it impossible to obtain the desired low density and thick foam. It became.
[0010]
In order to solve this problem, for example, as disclosed in JP 10-506858 A, carbon dioxide and water are sequentially pressed into a resin in a heated and melted state, and then immediately before extrusion foam molding. It was studied to adopt a method of sufficiently dispersing by a stirring method.
However, even if this method is employed, the problem that the foamed structure is still uneven and internal foaming cannot be solved.
[0011]
  The object of the present invention is to produce carbon dioxide and water as blowing agents, which are safer and more environmentally friendly than hydrocarbons and halogenated hydrocarbons, and use hydrocarbons and the like. New styrenic resin foam with low density, thick wall and uniform foam structureof,Efficient and easy manufacturingThe lawIt is to provide.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the inventors added a compatibilizing agent mainly for improving the compatibility of the styrene resin and water to the system composed of the styrene resin, carbon dioxide and water, and in the extruder. The improvement of the compatibility of the above components in the melt-mixed state was studied.
[0013]
As a result, when a nonionic surfactant having an HLB of 12 to 18 is used as the compatibilizer, the nonionic surfactant is particularly suitable for extrusion foam molding of a styrene resin as described above. Since the compatibility with water, styrene resin, etc. in the temperature range of 150 ° C. or lower is improved, the problem of non-uniform foam structure due to uneven dispersion of water is eliminated. 0.050 g / cm^ThreeThe inventors have found that a styrene resin foam having a low density, a high expansion ratio, a thickness of 10 mm or more, and a uniform foam structure can be obtained, and the present invention has been completed.
[0014]
  That is, in the method for producing a styrene resin foam of the present invention, carbon dioxide and water as a foaming agent and a nonionic surfactant having an HLB of 12 to 18 are added to a molten styrene resin., Carbon dioxide added amount W with respect to 100 parts by weight of styrene resin _C 2.0-6.0 parts by weight, water addition amount W _H 0.5 to 2.0 parts by weight, addition amount W of nonionic surfactant _S 0.1 to 1.0 parts by weight and W _C > W _H To beIt is characterized by adding, mixing, and extrusion foaming.
[0015]
In the present invention, the HLB of the nonionic surfactant is limited to 12 to 18, and the nonionic surfactant whose HLB is outside this range is apparent from the results of Examples and Comparative Examples described later. This is because the effect of improving the compatibility with water, styrene resin, etc. cannot be obtained, and a uniform foam without internal foaming cannot be produced.
[0016]
Nimura, of the inventors, together with the other inventors, extrude styrenic resin using water alone as a blowing agent or using water in combination with a small amount of nitrogen. It has been proposed to add a nonionic surfactant to the foam molding system (Japanese Patent Laid-Open No. 8-41236).
According to this method, as described in the 0014 column of the publication, the density is 2.6 × 10.^-1g / cm^ThreeOr more (0.26 g / cm^ThreeAlthough it is possible to produce a foam sheet having a thickness higher than that of the present invention and a thickness of 3.0 mm or less as compared with the present invention, it is possible to produce a foam structure having a low density and a thick wall as in the present invention. However, a uniform foam could not be obtained.
[0017]
The reason for this is the same as described above. In other words, in order to obtain a low-density and thick-walled foam, it is necessary to inject a large amount of foaming agent. However, both water and nitrogen have poor compatibility with styrene resins as described above. Even if a surfactant is added, the foam structure becomes non-uniform, and it is not possible to obtain a foam having a low density, a thick wall and a uniform foam structure.
[0018]
HLB (Hydrophile-Lipophile Balance) is an index indicating the balance between the hydrophilic group and the lipophilic group in the surfactant.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described below.
As described above, the present invention usually uses carbon dioxide and water as a foaming agent for extrusion foam molding, and uses a nonionic surfactant having an HLB of 12 to 18 as a compatibilizing agent. This is carried out in the same manner as in the extrusion foam molding.
[0020]
That is, carbon dioxide and water as a foaming agent and nonionic surfactant as a compatibilizing agent are added to and mixed with a styrene resin in a heated and melted state, and are extruded into the atmosphere through a die part of a mold to be foamed. Thus, a styrene resin foam is produced.
As an apparatus for carrying out such a manufacturing method, for example, a tandem extruder in which two first and second extruders are connected with a mixer 60 as necessary as shown in FIG. 1 is preferably used. Is done.
[0021]
The tandem extruder is a styrenic resin introduced into the hopper 11 as indicated by white arrows in the figure,
First, in the first extruder 10, as indicated by solid arrows in the figure from the nozzles 12a and 12b provided in the middle of the extruder 10 while being heated and melted at a temperature higher than that suitable for extrusion foaming. Carbon dioxide (nozzle 12a) and water (nozzle 12b) as a foaming agent are injected into and mixed in the presence of a nonionic surfactant as a compatibilizing agent, and as indicated by a dashed line arrow in the figure. To the mixer 60 continuously,
In this mixer 60, while continuously melting and mixing while applying a predetermined temperature and pressure, continuously fed to the second extruder 20,
Next, in this second extruder 20, while further mixing by rotation of the screw 20a, after adjusting to a predetermined temperature suitable for extrusion foaming,
-By continuously extruding and foaming in the atmosphere through the die part 31 of the mold 3 connected to the tip of the second extruder 20,
This is for continuously producing a styrene resin foam.
[0022]
In the figure, reference numeral 4 denotes a styrenic resin by cooling the resin 5 while regulating the expansion of the styrenic resin 5 extruded from the die 31 of the mold 3 in the thickness direction due to foaming. It is a pair of plate-shaped forming tools for forming a foam to a predetermined thickness.
The nonionic surfactant may be added from the hopper 11 together with the styrene resin, but it is more preferable to press the one dissolved in water together with water from the nozzle 12b.
[0023]
When such an extruder is used, carbon dioxide and water disclosed in, for example, the above-mentioned Japanese translation of PCT publication No. 10-506858 are sequentially pressed into a resin in a heated and melted state, and then immediately before extrusion foam molding. Compared to a method of sufficiently dispersing by a stirring method, there is an advantage that not only the foamed structure becomes uniform as described above, but also the productivity of the styrene resin foam is improved.
[0024]
That is, in the method of Japanese Patent Publication No. 10-506858, the resin that has been cooled to a temperature suitable for extrusion foaming and becomes highly viscous is dynamically stirred using a mixer or the like. Energy and time.
On the other hand, in the present invention, in the first extruder 10 or in the first extruder 10 and the mixer 60 that follows the first extruder 10, before cooling to a temperature suitable for extrusion foaming, a higher temperature and lower viscosity stage. Thus, since each component is sufficiently mixed, less energy is used and the time required for stirring is shorter, and the productivity of the styrene resin foam is improved.
[0025]
  Conditions for extrusion foaming using the tandem extruder shown in FIG.Out ofThe amount of water added as a blowing agent is less than the amount of carbon dioxideThere is a need.
  That is, the addition amount W of carbon dioxide with respect to 100 parts by weight of the styrene resin._C(Parts by weight) and amount of water added W_HExpressed as (parts by weight), W_C> W_HIsThere is a need.
[0026]
  If this condition is not satisfied, W_C≦ W_HIn the case where the nonionic surfactant is added, water cannot be uniformly dispersed in the styrene resin, the foam structure becomes non-uniform, and the low density and thick wall In addition, a foam with a uniform foam structure cannot be obtained.No.
  AlsoThe addition amounts of carbon dioxide and water, and nonionic surfactant are within the following ranges with respect to 100 parts by weight of styrene resin, respectively.There is a need.
[0027]
  Carbon dioxide: added amount W_C= 2.0 to 6.0 parts by weight
  Water: Addition amount W_H= 0.5 to 2.0 parts by weight
  Nonionic surfactant: addition amount W_S= 0.1 to 1.0 parts by weight
[However, among the above, carbon dioxide and water addition amount W_C, W_HIs W as described above._C> W_HIsThere is a needSo the amount of carbon dioxide added W_CIs 2.0 parts by weight, the added amount of water W_HIs less than 2.0 parts by weightNeedConversely, the amount of water added W_HIs 2.0 parts by weight, the amount of carbon dioxide added W_CIs a range exceeding 2.0 parts by weightThere is a need. ]
  Carbon dioxide addition amount W_CAnd / or water addition amount W_HHowever, if the amount is less than this range, the amount of foaming agent is generally insufficient.Can't get. Conversely, the amount of carbon dioxide added W_CAnd / or water addition amount W_HIf this exceeds this range, internal foaming will not occur and the foam expansion ratio will not increase.Can't get.
[0028]
  In consideration of obtaining a low-density, thick-walled foam with a uniform foam structure, the amount of carbon dioxide added W_CEven within the above range, is preferably about 2.0 to 4.0 parts by weight. For the same reason, the amount of water added W_HIs preferably about 1.0 to 2.0 parts by weight even within the above range.
  In addition, addition amount W of nonionic surfactant_SIs less than the above range, the effect of adding the nonionic surfactant is insufficient, and the foam structure is uneven due to uneven dispersion of water.Ru. Conversely, the addition amount W of the nonionic surfactant_SExceeding the above range, not only the addition effect is not obtained, but also excessive nonionic surfactant causes fluctuations in extrusion discharge, making extrusion difficult.Ru.
[0029]
Nonionic surfactant addition amount W_SIs preferably about 0.1 to 0.5 parts by weight even within the above range.
The melting, mixing temperature, extrusion temperature, etc. of the resin may be adjusted to the same level as before.
The density of the styrene resin foam thus produced is, for example, 0.025 to 0.050 g / cm.^ThreeEspecially 0.040 g / cm^ThreeIn the following, the thickness is 10 to 120 mm, particularly 15 mm or more, and the average bubble diameter is 0.10 to 0.80 mm, which is low density and thick, and the foam structure is uniform.
[0030]
As the nonionic surfactant, those having an HLB of 12 to 18 as described above are used. As such nonionic surfactants, among various surfactants classified as polyethylene glycol type or polyhydric alcohol type nonionic surfactants, any of various compounds having an HLB of 12 to 18 is used. Is possible.
[0031]
For example,
Alkyl and alkylallyl polyoxyethylene ether (more specifically, single-chain polyoxyethylene ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, etc.) Ether type surfactants such as alkylallyl formaldehyde condensed polyoxyethylene ethers (more specifically, ethylene oxide derivatives of alkylphenol formalin condensates), polyoxyethylene polyoxypropylene block copolymers, polyoxyethylene polyoxypropyl alkyl ethers, etc. ,
Ether ester type surface activity such as polyoxyethylene ether of glycerin ester (more specifically, polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil and hydrogenated castor oil), polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, etc. Agent,
Ester type surfactants such as polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester,
Nitrogen-containing surfactants such as fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, amine oxide,
And a compound having an HLB of 12 to 18 as described above is preferably used.
[0032]
Note that the HLB of the nonionic surfactant is preferably about 14 to 16 even within the above range, considering the function as a compatibilizing agent.
As the styrenic resin, polystyrene, that is, a homopolymer of styrene is most preferably used, and a copolymer of styrene and another vinyl monomer can also be used.
[0033]
Examples of other vinyl monomers copolymerized with styrene include α-methylstyrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, and maleic anhydride.
In addition, as a styrene resin, in order to improve the impact resistance of the foam, for example, a diene rubber-like heavy polymer such as polybutadiene, styrene-butadiene copolymer, ethylene-propylene-nonconjugated diene terpolymer is used. A rubber-modified styrene resin to which a coalescence is added, so-called high impact polystyrene may be used.
[0034]
These styrenic resins can be used alone or in combination of two or more.
As the styrenic resin, in order to foam the foam well, the melt flow rate R particularly at 200 ° C.₁(G / 10 min) and melt tension T₁(G · f) is the formula (1) (2):
2 ≦ R₁≦ 10 (1)
T₁≧ −0.65R₁+11.6 (2)
It is preferable to use one having a relationship represented by
[0035]
The melt flow rate (melt flow rate: MFR) R at 200 ° C. here₁Is a condition 8 (test temperature: 200 ° C., test load: stipulated in the same method in accordance with the test method described in Japanese Industrial Standard JIS K7210 “Thermoplastic Plastic Flow Test Method”. The value measured at 5.00 kgf).
Also, melt tension T₁These are values measured under the following conditions using Capillograph PMD-C manufactured by Toyo Seiki Seisakusho.
[0036]
Test temperature: 200 ° C
Preheating time: 5 minutes
Extrusion speed: 100mm / min
Winding speed: 12mm / min
Capillary: Diameter 1.00mm, length 10mm, inflow angle 45 °
As mentioned above, styrene-based resins have low compatibility with carbon dioxide and water as foaming agents and poor compatibility, producing foams with a uniform cell structure, high thickness and high expansion ratio. It is not easy to do.
[0037]
However, when a styrene resin is used in which the melt flow rate at 200 ° C. and the melt tension are in the relationship represented by the above formulas (1) and (2), the resin foams in spite of the high melt tension. Since the temperature range is low and the melt tension at the time of foaming is high, the occurrence of internal foaming can be reliably prevented. Therefore, as described above, it is possible to satisfactorily produce a styrene resin foam having a low density, a high expansion ratio, a thick wall, and a uniform cell structure.
[0038]
As styrene resin, melt flow rate R₁Exceeds 10 g / 10 min, that is, melt tension T₁When a low resin is used, the foaming temperature range is low, so that a larger amount of carbon dioxide can be dissolved in the resin, but the resin does not have a melt tension that can withstand high foaming. Alternatively, since the foaming temperature region is low, the foaming temperature becomes equal to or lower than the Vicat softening point as soon as foaming and cooling are performed. Therefore, the foaming ratio of the foam may not be increased as described above.
[0039]
Conversely, the melt flow rate R₁Is less than 2 g / 10 min, ie melt tension T₁When a styrene resin having a high value is used, the foaming temperature region becomes high, and the amount of carbon dioxide dissolved in the resin becomes small.
Furthermore, the melt flow rate R₁And melt tension T₁Does not satisfy the formula (2),
T₁<-0.65R₁+11.6
In this case, since the melt tension is low relative to the melt flow rate, internal foaming is likely to occur immediately after foaming. Therefore, in this case as well, there is a possibility that a thick styrene resin foam having a high expansion ratio cannot be produced.
[0040]
The melt flow rate R of styrene resin₁Is preferably within the range of 4 to 7 g / 10 min even within the range of the formula (1). Also, melt tension T₁Is particularly within the range of the formula (2).
T₁≦ −0.65R₁+15
Is preferred.
A foam nucleating agent (bubble adjusting agent) may be added to the styrenic resin in order to further promote the homogenization of the cell structure. Examples of the foam nucleating agent include inorganic fine powders such as talc, calcium carbonate, clay, magnesium oxide, zinc oxide, glass beads, glass powder, titanium oxide, carbon black, anhydrous silica, and calcium silicate. The particle size of the foam nucleating agent is preferably 50 μm or less, particularly preferably about 10 to 30 μm. Moreover, it is preferable that the addition amount of a foam nucleating agent is about 0.1-1 weight part with respect to 100 weight part of styrene resin.
[0041]
Examples of styrenic resins include colorants, flame retardants, lubricants (hydrocarbons, fatty acids, fatty acid amides, esters, alcohols and other waxes, metal soaps, silicone oils, low molecular weight polyethylene, etc.) Various additives such as spreading agents (liquid paraffin, polyethylene glycol, polybutene, etc.) and dispersants may be added. These additives are added to the extent that they do not interfere with the production of the foam and do not affect the properties of the produced foam.
[0042]
Further, as shown in FIGS. 1 and 2A, a resin extrusion flow path 30 and a base 31 are arranged in communication with each other as a mold 3 for extrusion foam molding, and the resin extrusion flow path 30 is also provided. Width S in the direction corresponding to the thickness direction of the styrene resin foam₂And the width S in the same direction of the base 31₁Ratio S to₂/ S₁However, equation (3):
40 ≦ S₂/ S₁≦ 100
When using a resin having the above-mentioned range, particularly by using a styrenic resin having the above-mentioned characteristics, the amount of the foam nucleating agent is reduced from the above-mentioned range, or the foam nucleating agent is not used at all. Without the addition, it is possible to produce the same good foam, and there is an advantage that the ash content during incineration can be reduced.
[0043]
That is, when the mold 3 having such a dimension is used, the width S of the flow path 30 disposed at the tip of the resin extrusion flow path 30.₂Narrower width S₁And a predetermined length (land length) L₁Since the pressure inside the extruder 20 is maintained at a high pressure necessary for dissolving carbon dioxide up to the tip of the mouthpiece 31, the amount of carbon dioxide dissolved in the resin is increased. The foaming ratio of the foam can be increased and the cell structure can be made uniform.
[0044]
Further, as is apparent from the above effect, the width S of the base 31 is obtained.₁And land length L₁There is also an advantage that the internal pressure of the second extruder 20 can be freely adjusted by adjusting.
Furthermore, the width S of the resin extrusion flow path 30 provided in front of the base part 31.₂However, the styrene-based resin in the flow path 30 also functions to have a shape memory so that the styrene resin foams into the thick wall as described above after being extruded from the base 31 into the atmosphere.
[0045]
Therefore, by using the mold 3, the cell structure is as uniform as when a predetermined amount of the foam nucleating agent is added, and has a low density and a high expansion ratio as described above. It is possible to produce the resin-based resin foam satisfactorily without reducing the amount of the foam nucleating agent added, or without adding any foam nucleating agent.
[0046]
In the above mold 3, the ratio S₂/ S₁When the value exceeds 100, a portion in which the resin does not flow in the mold 3 may occur, and an unfoamed resin may be generated. Also ratio S₂/ S₁When is less than 40, as is clear from the above description, a thick styrene resin foam may not be produced satisfactorily. Ratio S₂/ S₁In view of avoiding these problems and performing good molding, it is particularly preferable to be within the range of 60 to 80 even within the above range.
[0047]
In the illustrated mold 3, the resin extrusion flow path 30 and the base part 31 are connected by a tapered surface 32. For example, as shown in FIG. 2B, the resin extrusion flow path 30 and the base part are connected. 31 may be connected by a vertical surface 33.
[0048]
【Example】
Hereinafter, the present invention will be described based on examples and comparative examples.
The density of the plate-like styrene resin foam produced in the following examples and comparative examples was calculated by actually measuring the weight per unit volume. The average bubble diameter was measured using a scanning electron microscope [JSM T-300 manufactured by JEOL Ltd.] in accordance with the measurement method described in ASTM D2842-69. That is, each foam diameter in the resin flow direction (MD), width direction (TD) and thickness direction (VD) of the foam obtained by extrusion foam molding is measured, and the average value is obtained by arithmetically averaging the measured values. The diameter was determined.
[0049]
Example 1
The following components were dry blended to prepare a mixture.

Next, this mixture is supplied to the hopper of the first extruder of the tandem extruder in which the first and second extruders are connected with the pin mixer interposed therebetween, and mixed in the first extruder. After melting and mixing at a temperature of 200 ° C., from two nozzles provided in the middle of the first extruder, into the first extruder, carbon dioxide as a blowing agent and water as a blowing agent are used as compatibilizers. A solution in which polyoxyethylene lauryl ether (HLB = 16) was dissolved was injected and added.
[0050]
The amount of each component added was 3.8 parts by weight of carbon dioxide, 1.5 parts by weight of water, and 0.3 parts by weight of polyoxyethylene lauryl ether per 100 parts by weight of polystyrene.
Next, the melt mixture after the press-fitting is continuously melted and mixed for a while in the first extruder, and then continuously supplied to the pin mixer. In the pin mixer, the mixing temperature is 180 ° C. and the mixing pressure is 200 kg / cm.²The mixture was further sufficiently melted and mixed under the condition of a rotational speed of 60 rpm.
[0051]
Then, the molten mixture is continuously supplied from the pin mixer to the second extruder, and after being uniformly cooled to 130 ° C., which is a temperature suitable for extrusion foaming, in the second extruder, Between a pair of plate-shaped molding tools, which are connected to the tip and foamed by being continuously extruded into the atmosphere through a slit-shaped mold having a lip width W = 50 mm and a thickness t = 1.4 mm. Then, the styrenic resin foam was manufactured by cooling while correcting the thickness so as to be 30 mm which is the same as the interval of the molding tool.
[0052]
The density of the obtained foam is 0.030 g / cm.^ThreeThe average bubble diameter was 0.6 mm.
Example 2
A styrene resin foam having a thickness of 30 mm was produced in the same manner as in Example 1 except that 0.3 parts by weight of polyoxyethylene lauryl ether having an HLB of 12.6 was used as a compatibilizing agent.
[0053]
The density of the obtained foam is 0.032 g / cm.^ThreeThe average bubble diameter was 0.5 mm.
Comparative Example 1
A styrenic resin foam was produced in the same manner as in Example 1 except that the nonionic surfactant as a compatibilizer was not added. However, internal foaming occurred and the internal structure was uniformly foamed. I couldn't get a body.
[0054]
Comparative Example 2
A styrenic resin foam was produced in the same manner as in Example 1 except that 0.3 parts by weight of polyoxyethylene octylphenyl ether having an HLB of 9.0 was used as a compatibilizing agent. Foaming occurred, and it was impossible to obtain a foam having a uniform internal structure.
[0055]
The results are summarized in Table 1.
[0056]
[Table 1]

[0057]
【The invention's effect】
As described above in detail, according to the present invention, carbon dioxide and water, which are safer and more environmentally friendly than hydrocarbons and halogenated hydrocarbons, are used as blowing agents, and hydrocarbons. It is possible to produce a novel styrene resin foam having a low density, a thick wall, and a uniform foam structure, similar to the case of using a material.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an extruder for carrying out the production method of the present invention.
FIGS. 2 (a) and 2 (b) are sectional views showing an example of a mold used in the extruder.

Claims (3)

The styrene resin in a molten state, carbon dioxide and water as a blowing agent, and HLB is 12 to 18 a nonionic surfactant, the addition amount W _C of the carbon dioxide with respect to 100 parts by weight of styrene resin 2.0 -6.0 parts by weight, water addition amount W _H is 0.5-2.0 parts by weight, nonionic surfactant addition amount W _S is 0.1-1.0 part by weight, and W _C > A method for producing a styrenic resin foam , comprising adding, mixing, and extrusion-foaming so as to be _WH .   Using a tandem extruder in which the first and second extruders are connected, first, in the first extruder, the foaming agent is converted into a styrene resin in a molten state at a temperature higher than the temperature suitable for extrusion foaming. Carbon dioxide and water are added and mixed uniformly in the presence of a nonionic surfactant, and then this mixture is adjusted to a temperature suitable for extrusion foaming in a second extruder and then subjected to extrusion foam molding. The manufacturing method of the styrenic resin foam of Claim 1.   The styrene according to claim 2, wherein a mixer is provided between the first extruder and the second extruder, and the mixture obtained by the first extruder is further melted and mixed by the mixer and then supplied to the second extruder. Of producing a resin-based resin foam.

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