JP2002128941A - Extrusion-expanded styrene board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extrusion-expanded styrene board excellent in resin performances such as rigidity, strength and the like and remarkably decreased in volatilization of organic compounds. SOLUTION: The extrusion expanded styrene board is obtained by extrusion expansion molding of a composition comprising 100 pts.wt. of a styrenic polymer (a), 0.1-5.0 pts.wt. of a nucleating agent (b) and 0-3.0 pts.wt. of a liquid paraffin (c), where the styrenic polymer (a) is a polymer mainly composed of a styrene bond unit obtained by an anion polymerization method using an organic lithium initiator, has a weight-average molecular weight ranging from 50,000 to 1,000,000 and contains less than 1,000 ppm of a styrenic low-molecular weight component having a molecular weight within the range of 140-400 (provided that the styrenic low-molecular weight component comprises a styrene oligomer component and a non-styrene oligomer component) containing less than 500 ppm of the non-styrene oligomer component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene-based polymer extruded foam board. Extrusion foam board made of styrene polymer takes advantage of its features,
It is widely used for applications such as building materials for general housing, heat insulating materials for freezing and cooling facilities, and core materials for chemical tatami mats.

[0002]

2. Description of the Related Art A single-layer extruded foam board of a styrene polymer or a laminated extruded foam board of a styrene polymer obtained by laminating a thermoplastic resin film of polystyrene, polyolefin, etc., is a hard and strong foam made of closed cells. It is a plate-like molded product and has excellent features such as light weight, heat insulation, chemical stability, low water absorption and low moisture absorption, and easy workability. Because of these features and the fact that the construction method has already been established, it has been evaluated and adopted as a heat insulating material that is easy to obtain the total heat insulating performance of building materials. Also,
In addition to heat insulation, it has been evaluated as a core material for chemical tatami mats, which has been evaluated for lightness and hygiene, and is being replaced by straw floors.
The market is expanding.

[0003] Generally, a styrene polymer used for an extruded styrene board is produced by a bulk radical polymerization method and a suspension radical polymerization method. In particular, a styrene-based polymer produced by the bulk radical polymerization method has a feature that it has a small amount of impurities due to additives and is inexpensive, and is preferably used for the production of an extruded foamed styrene board. The extruded foamed styrene board was prepared by adding a foaming nucleating agent such as talc or calcium carbonate and, if necessary, a formability modifier such as liquid paraffin to a styrene-based polymer, melting and mixing using an extruder, and press-fitting the foaming agent. Thereafter, it is manufactured by extruding and foaming from a flat die or a circular die to form an extruded foam board.

As the foaming agent, generally used are hydrocarbons and halogenated hydrocarbons which are gaseous at ordinary temperature, such as industrial butane and dichlorodifluoromethane, or carbon dioxide gas and nitrogen gas. By the way, it is well known that the radical polymerization method generally involves the formation of oligomers during the production of a styrene-based polymer, and that styrene monomers are also likely to remain. For example, review articles (Encyclopedia of chemical technology,
Kir k-Othmer, Third Edition, John Wily & Sons, Volume 21, 8
According to p. 17), thermal polymerization of styrene at 100 ° C. or higher involves by-products of oligomers such as styrene dimer and styrene trimer, and the amount is about 1% by weight.
Specific oligomer components are mainly 1-phenyl-
It consists of 4- (1'-phenylethyl) tetralin and 1,2-diphenylcyclobutane. In addition, 2,4-diphenyl-1-butene and 2,4,6-triphenyl-1-
It is said that hexene exists.

In general, the bulk radical polymerization process is 80
Polymerization is carried out at -180 ° C, and then the solvent and unreacted monomers contained are removed by heating and volatilization to recover the polymer. However, the radical polymerization method cannot attain a high degree of conversion of a monomer into a polymer, and even after heating and devolatilization, generally a relatively large amount of unreacted styrene monomer is converted into a styrene-based polymer. Remains inside. For this reason, a method of devising the devolatilization step, for example, a method of azeotropically removing the remaining styrene monomer with water by heating and devolatilizing, further adding water, devolatilizing after mixing, and the like has been developed. However, a satisfactory level has not been achieved. In addition, oligomers such as dimer and trimer of styrene by-produced are less likely to volatilize, and generally, most of them remain in the polymer.

When the styrene-based polymer thus produced is analyzed, residues, impurities and by-products during polymerization are detected from the raw materials. Specifically, styrene, α
-Methylstyrene, n-propylbenzene, iso-propylbenzene, 2,4-diphenyl-1-butene,
1,2-diphenylcyclobutane, 1-phenyltetralin, 2,4,6-triphenyl-1-hexene,
3,5-triphenylcyclohexane, 1-phenyl-
4- (1′-phenylethyl) tetralin and the like are contained in the styrene-based polymer. As described above, the styrene-based polymer of the radical polymerization method currently widely used contains a large amount of low molecular components such as a styrene monomer and a styrene oligomer due to the production method. Furthermore, styrene-based polymers obtained by these radical polymerization methods are generally inferior in stability, and the amount of low-molecular components such as styrene monomers and styrene oligomers in the polymer depends on the mechanical history or thermal history during molding. Tends to increase. Low-molecular components newly generated during molding also have the same problems as low-molecular components generated during polymerization.

Specifically, such a styrenic polymer containing a large amount of low molecular components has a problem that the extruded foamed styrene board has insufficient heat stability at the time of processing and adheres to a mold or a molded product. May come. In addition, the obtained extruded styrene board has low molecular components such as styrene monomer and styrene oligomer originally contained in the raw material styrene-based polymer, and is newly formed during processing into extruded styrene board. Low molecular components. Although the amount of low molecular components contained in these styrenic polymers is very small, it has an unfavorable effect on moldability and product performance. Therefore, measures such as setting the temperature at the time of molding and processing low and keeping the share of polymer mixture low, etc. are taken to make the processing conditions mild, but these measures are accompanied by the cause of productivity and moldability deterioration, There are also evils.

[0008] In terms of the performance of the molded final product, when a low molecular component is contained in a large amount in the styrenic polymer, for example, when used in a house building material or a chemical tatami mat, there is a concern about volatilization thereof. Specifically, volatile organic compounds (V
OC) is concerned about one of the causes of sick house syndrome,
There is a need for building materials that do not contain or reduce VOCs. Further, if the styrene-based polymer contains a large amount of low molecular components, the rigidity and strength of the product are undesirably reduced. The idea of actively removing low molecular components from the styrene-based polymer in the bulk radical polymerization method is already known. For example, in the production of a styrene-based polymer, removal of low-molecular components by vacuum devolatilization under heating has already been performed. However, styrene oligomers have low volatility, and excessive heating may cause formation of new styrene monomers and styrene oligomers, and there is a natural limitation in removing low molecular components. In contrast to these radically polymerized styrene-based polymers, anionic polymerization-based styrene-based polymers using organic lithium or the like have long been known in the art.

For example, US Pat. No. 5,391,655, US Pat. No. 5,089,572, US Pat. No. 4,883,846, US Pat. No. 4,748,2
22, U.S. Pat. No. 4,205,016,
U.S. Pat. No. 4,200,713, U.S. Pat.
16,348, U.S. Pat. No. 3,954,894, and U.S. Pat. No. 4,859,748. To summarize these U.S. patented technologies:
A method related to a production apparatus such as a method of lowering the degree of dispersion in an anionic polymerization method (U.S. Pat. No. 4,883,846) and a method of using a continuous polymerization method in producing polystyrene by an anion polymerization method (US Pat. No. 4,016) , 3
No. 48, U.S. Pat. No. 4,748,222,
U.S. Pat. No. 5,391,655), a method for producing an initiator used in an anionic polymerization system and application examples (U.S. Pat. No. 4,205,016, U.S. Pat. No. 5,089,7).
52 specification). US Patent 4,859,
No. 748 discloses a method for controlling an anionic polymerization reaction of styrene in a continuous stirred tank reactor. But,
In these anionic polymerization techniques for styrene polymers, there was no disclosure of a styrene-based low-molecular component that directly leads to achieving the main effects of the present application.

Further, in recent years, Japanese Patent Application Laid-Open No. 10-110
No. 074 discloses that a polymer having less oligomers can be obtained in anionic polymerization using organolithium as an initiator. In the description of Reference Example 2, a batch polymerization method of styrene monomer using organolithium was used.
A monodisperse polymer having a narrow molecular weight distribution is obtained, and the dimer content is 1 pp by drying after adding an antioxidant.
m, a styrene polymer having a trimer content of 170 ppm was obtained. Japanese Patent Application Laid-Open No. 2000-143725 relates to a styrenic polymer by an anionic polymerization method and a method for producing the same, wherein the styrene dimer content is 80 ppm.
The following discloses a styrene-based polymer having a styrene trimer content of 800 ppm or less, a method for producing the styrene-based polymer, and use in food applications. As described above, the following items (a) and (b) have been already known. (A) A styrene polymer can be obtained by an anionic polymerization method using organolithium. (B) The styrene-based polymer obtained by anionic polymerization using organolithium has a lower content of styrene dimer and styrene trimer than a styrene-based polymer obtained by radical polymerization.

However, the styrenic polymers obtained by these anionic polymerization methods have some problems,
It has not yet been widely used for extruded foamed styrene board applications. That is, there are the following problems (c) to (e). (C) The styrene polymer produced by the anionic polymerization method using organolithium is more expensive to produce than the styrene polymer produced by the bulk radical polymerization method. (D) When anionic polymerization is carried out at a high temperature and a high monomer concentration in order to increase the productivity and reduce the cost, styrene-based low molecular components, particularly dimers and trimers, increase.
One of the major features of anionic styrene polymers is that they are lost. (E) A styrene-based polymer obtained by an anionic polymerization method using organolithium generally has a narrow molecular weight distribution and is inferior in processability.

Next, each of the problems in the above-mentioned conventional technology will be specifically described. One of the major reasons for the high cost of the production of item (c) is that the anionic polymerization method is inferior in productivity. That is, in the bulk radical polymerization method, the monomer concentration is 90% by weight or higher, whereas in the anion polymerization method, particularly in the batch process, the monomer concentration is usually 25% by weight. %. This is mainly due to the difficulty of removing the heat of polymerization in the anionic polymerization method, and production at a low monomer concentration is inferior in productivity. That is, in the anionic polymerization method using organolithium, at a high temperature exceeding 120 ° C., the initiator is significantly deactivated. Therefore, in order to complete the reaction sufficiently, it is necessary to suppress the polymerization temperature to 120 ° C. or less by removing heat. However, at high monomer concentrations, the polymerization rate and polymerization solution viscosity increase significantly. Therefore, the amount of heat and the rate of heat generation increase, and the heat removal property decreases, making temperature control difficult.

This can be solved in a laboratory reactor by effectively removing heat. However, it becomes a serious problem in a large plant reaction vessel having a relatively small heat transfer area, and it is extremely difficult to perform batch polymerization at a high monomer concentration. Therefore, in the anionic polymerization method, a low monomer concentration lowers productivity and is a major cause of high cost. As a measure to fundamentally solve the heat removal problem by high-concentration polymerization, there is a proposal of a method of continuous polymerization using a special reactor having a high heat removal ability. For example, US Pat.
No. 9,748 discloses a method in which a high-concentration monomer of 30 to 80% by weight is continuously flowed into a tubular circulation-type reaction tank having a large surface area and a high heat removal capability to carry out anion polymerization. ing. Although anionic polymerization with a high monomer concentration can be achieved by such a method, another problem remains. That is,
The flow of the high-viscosity polymer solution in the thin tube is in an unstirred state. Such polymerization in a non-stirred tube-type reaction vessel causes gel formation depending on the conditions, and eventually causes blockage of the tube-type reaction vessel, which is a fatal drawback.

The item (d) is concerned with a styrene-based low molecular component, especially a dimer and a trimer. Unlike the radical polymerization method, it is generally considered that there is no by-product of styrene dimer and trimer in the anionic polymerization method. However, as a result of the inventor's diligent studies, even in anionic polymerization using organolithium, the formation of dimers and trimers may occur to a considerable extent at the practical polymerization conditions of temperature and monomer concentration. found.
In addition to styrene dimers and trimers, it has been found that styrene-based low molecular components, which are specific to anionic polymerization, are formed. This is mainly produced by reacting a specific solvent or a trace amount of impurities contained therein with a styrene monomer in the coexistence of organolithium, and has a structure that can no longer be said to be a styrene oligomer. That is, even in the anionic polymerization method, the obtained styrene-based polymer has a problem that a styrene-based low-molecular component having a molecular weight in the range of 140 to 400 is contained in a nonnegligible amount. The result became clear.

The inferior processability of the styrene-based polymer obtained by the anionic polymerization method in the item (e) is mainly due to a narrow molecular weight distribution. In a batch polymerization method or a continuous polymerization using a tubular reactor, the molecular weight distribution of the polymer obtained is generally extremely narrow. For example, Japanese Patent Application Laid-Open No. 10-1100 described above
No. 74 discloses a monodisperse polymer having a narrow molecular weight distribution (Mw / Mn = 1.04) by a batch polymerization method of a styrene monomer using organolithium in the description of Reference Example 2. I have. Polymers having a narrow molecular weight distribution are inferior in moldability and processability and are usually not preferred.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an extruded foamed styrene board which is excellent in resin performance such as rigidity and strength, and in which volatilization of an organic compound is remarkably reduced.

[0017]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention. That is, the composition obtained using a styrene-based polymer having a small amount of a styrene monomer and other styrene-based low-molecular components obtained under a specific polymerization condition range is excellent in molding into an extruded foamed styrene board and processability. In addition, the obtained extruded expanded styrene board was found to be excellent in various physical properties, in particular, rigidity and strength, and remarkably reduced the volatilization of the organic compound. The invention is set out in the claims. That is, (a) 100 parts by weight of a styrenic polymer, (b) 0.1 to 5.0 parts by weight of a nucleating agent, and (c) 0 to 3.0 parts by weight of liquid paraffin. A foamed styrene board, wherein (a) the styrene-based polymer is a polymer mainly composed of styrene-bonded units obtained by an anionic polymerization method using an organic lithium initiator, and has a weight average molecular weight of 50,000 to 100 Styrene-based low molecular weight component having a molecular weight of 140 to 400 (however,
The styrene-based low molecular weight component comprises a styrene oligomer component and a non-styrene oligomer component. ) Is 1000 ppm
Extruded foamed styrene board characterized in that the amount of the non-styrene oligomer component is less than 500 ppm.

The styrenic polymer which can be used in the composition constituting the extruded styrene board of the present invention is described in, for example, Japanese Patent Application No. 2000-139,087.
It can be obtained by the method described in 001-136262. Specifically, the first having a back-mixed flow
In a continuous anionic polymerization process in which a raw material system having the following composition (A) is continuously charged from one of the reaction tanks and a production system is continuously extracted from the other, the internal temperature of the reaction tank is set to 40 to
120 ° C., and controlling the average ratio of the styrene monomer, hydrocarbon solvent and styrene polymer present in the reaction vessel to the total amount of the monomer to less than 10% by weight. The styrene-based polymer solution obtained is devolatilized and dried to obtain a styrene-based polymer having a small amount of low molecular components. (A) Styrene-based monomer 1.0 kg Hydrocarbon solvent 0.1-3 kg Organic lithium compound 0.5-200 mmol The styrene-based polymer in the composition constituting the extruded foamed styrene board of the present invention is a styrene monomer. Even if it is a homopolymer or a copolymer containing a styrene monomer as a main component and another vinyl aromatic hydrocarbon, or a copolymer partially containing a conjugated diene monomer such as butadiene or isoprene I do not care. Processability of resin by these copolymer composition,
The softening temperature and rigidity can be adjusted, which is preferable in some cases.

The molecular weight of the styrenic polymer must be in the range of 50,000 to 1,000,000 by weight average molecular weight. Preferably 100,000 to 600,000, more preferably 150,000 to 5
It is in the range of 100,000, particularly preferably 200,000 to 400,000. If the weight average molecular weight is too low, various mechanical properties, such as strength and rigidity, of an extruded expanded styrene board obtained by molding the composition are undesirably reduced. On the other hand, if the weight average molecular weight is too high, the molding and processability of the composition are undesirably reduced. The molecular weight distribution (M) represented by the ratio of the weight average molecular weight to the number average molecular weight of the styrenic polymer
w / Mn) is generally 1.2 to 10, preferably 1.5
-5, particularly preferably 2-4. If the molecular weight distribution is too narrow, processability and specific resin performance, such as impact strength and foaming properties, are undesirably reduced. Also, when the width is too large, specific resin performance such as flow characteristics at the time of molding and the rigidity of the extruded expanded styrene board at the time of heating are lowered, which is not preferable.

The styrenic polymer used in the present invention must contain less than 1000 ppm of the low molecular weight styrene component having a molecular weight of 140 to 400 and less than 500 ppm of the non-styrene oligomer component. The styrenic low molecular weight component is preferably less than 600 ppm, more preferably less than 400 ppm, particularly preferably less than 200 ppm. The non-styrene oligomer component therein is preferably less than 300 ppm, more preferably less than 200 ppm, particularly preferably less than 100 ppm. The styrene-based low molecular weight component having a molecular weight of 140 to 400 contained in the styrene-based polymer used in the present invention comprises a styrene oligomer component and a non-styrene oligomer component. Specifically, the styrene oligomer component mentioned here is a dimer and a trimer of styrene. The non-styrene oligomer component is a styrene oligomer excluding these styrene oligomers and having a molecular weight of 140 to 1 having 1 to 3 phenyl groups.
It is a low molecular component in the range of 400.

The styrene dimer has a molecular weight of 208 and is composed of 2,4-diphenyl-1-butene and cis-1,2-.
Diphenylcyclobutane, trans-1,2-diphenylcyclobutane and the like. The trimer of styrene has a molecular weight of 312 and 2,4,6-triphenyl-1-
Hexene, 1-phenyl-4- (1′-phenylethyl) tetralin (including four isomers), 1,3,5
-Triphenyl-cyclohexane and the like. The non-styrene oligomer component is a hydrocarbon compound having 1 to 3 aromatic rings in the molecule. Specifically, as a hydrocarbon compound having two aromatic rings, 1,3-diphenylpropane, 1,3-diphenylbutane, 2,4-diphenylpentane, and as a hydrocarbon compound having three aromatic rings,
Examples include 3,5-triphenylpentane, 1,3,5-triphenylhexane, and 1,2,4-triphenylcyclopentane.

These non-styrene oligomer components are mainly formed by reacting a specific solvent or a contained impurity with a styrene monomer in the coexistence of organolithium, and have a structure which can no longer be said to be a styrene oligomer. Have. For example,
One or two molecules of styrene are added to the contained toluene to produce 1,3-diphenylpropane or 1,3,5-triphenylpentane. Also, one or two molecules of styrene are added to ethylbenzene to form 1,3-
Diphenylbutane and 1,3,5-triphenylhexane are formed. In addition, the formation mechanism is not necessarily clear, such as the styrene polymer being decomposed and formed,
1,2,4-Triphenylcyclopentane, 2,4-diphenylpentane, 1,2-diphenylcyclopropane, and the like are also found in the styrene-based polymer after heat devolatilization.

The styrene monomer contained in the styrene polymer used in the present invention is preferably less than 500 ppm. More preferably less than 200 ppm, particularly preferably less than 100 ppm, and most preferably less than 20 ppm. The residual hydrocarbon solvent contained in the styrene polymer used in the present invention is preferably less than 1000 ppm. It is more preferably less than 300 ppm, particularly preferably less than 100 ppm. When the content of these low-molecular components, that is, the styrene monomer, the styrene-based low-molecular component and the residual hydrocarbon solvent is large, the thermal stability during molding and processing of the composition containing the styrene-based polymer is not sufficient. Inferior in heat resistance expressed by rigidity during heating. The low molecular component contained in the composition is diffused or bleeds from the inside of the molded article to the surface, so that printing is difficult to take or the printing is easily peeled. Further, there may be a problem that low molecular components contained in the composition are eluted or volatilized. In particular, when the amount of the styrene-based low-molecular component is large, there may be a problem that an oily substance adheres to a mold or a molded product during molding and processing. When the amount of the styrene monomer is less than 20 ppm, the amount of the styrene-based low molecular weight component having a molecular weight in the range of 140 to 400 is 200 ppm or less, and the amount of the non-styrene oligomer component is 100 ppm or less, almost no diffusion or elution is observed.

The nucleating agent used in the extruded styrene board of the present invention is a foaming nucleating agent, and a known nucleating agent for foam molding of a styrene polymer can be used. Specific examples include talc, calcium carbonate, magnesium carbonate, titanium oxide, silica and the like. The amount of nucleating agent used is styrene-based polymer 10
It must be in the range of 0.1 to 5 parts by weight per 0 parts by weight. Preferably it is in the range of 0.2 to 4 parts by weight, particularly preferably 0.5 to 2 parts by weight. If the nucleating agent is too small, the size of the bubbles becomes uneven and large, which is generally not preferable. If the nucleating agent is too much, the bubble size becomes extremely small and the thickness of the partition walls becomes extremely thin, which is not preferable in some cases. The composition constituting the extruded styrene board of the present invention contains liquid paraffin in an amount of 0 or 0.01 to 3 parts by weight, preferably 0.1 to 100 parts by weight, per 100 parts by weight of the styrene polymer.
1 to 1.5 parts by weight, more preferably 0.5 to 2 parts by weight can be added. With the addition of liquid paraffin,
The viscosity of the composition can be reduced, and the foam moldability can be improved.
However, the addition in an amount exceeding 3 parts by weight is generally not preferable because the foaming characteristics are deteriorated.

By adjusting the molecular weight of the styrenic polymer and the amount of liquid paraffin to be added, the composition used in the present invention is measured at a temperature of 220 ° C. with a twin capillary rheometer (constriction type viscometer). It is preferable that the value of the elongational viscosity of the composition changes continuously within a range of 10,000 to 50,000 Pa · sec at a shear rate of 10 to 1000 sec ⁻¹ . Furthermore, 20000
The composition constituting the extruded expanded styrene board of the present invention, which is particularly preferably changed continuously in the range of 40,000 Pa · sec, has thermal or mechanical stability,
In order to improve the antioxidant property, weather resistance, and light resistance, various stabilizers that are known to be used for the styrenic polymer can be added. Examples thereof include phenol stabilizers, phosphorus stabilizers, nitrogen stabilizers, and sulfur stabilizers.

As a method for stabilizing polystyrene,
The addition of 4,6-trisubstituted phenols is known to be particularly advantageous. Preferred examples of the 2,4,6-trisubstituted phenol include 2,6-di-t-butyl-4-methylphenol and triethylene glycol-bis- [3- (3-
t-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionate,
1,3,5-trimethyl-2,4,6-tris (3,5
-Di-t-butyl-4-hydroxybenzyl) benzene, n-octadecyl 3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate, 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate, 2
[1- (2-hydroxy3,5-di-t-pentylphenyl)]-4,6-di-t-pentylphenyl acrylate, tetrakis [methylene 3- (3,5-di-t-butyl-4-) (Hydroxyphenyl) propionate] methane, 3,9bis [2- {3- (t-butyl-4-hydroxy-5-methylphenyl) propynyloxy} -1,
1-dimethylethyl] -2,4,8,10-tetraoxo [5,5] undecane, 1,3,5-tris (3 ′,
5'-di-t-butyl-4'-hydroxybenzyl)-
s-Triazine-2,4,6 (1H, 2H, 3H) -trione, 1,1,4-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4,4′-butylidenebis (3-methyl-6-t-butylphenol) and the like. These stabilizers can also be mixed in the extrusion foamed styrene board forming step. However, addition at the solution stage after the polymerization of the styrenic polymer is particularly preferred in that the mixing is easy and the deterioration of the polymer in the solvent recovery step can be suppressed.

The composition constituting the extruded styrene board of the present invention can be mixed with a resin additive known for use in a styrene polymer resin, if necessary. Examples include dyes, pigments, fillers, lubricants, release agents, plasticizers,
And antistatic agents. Further, the composition constituting the extruded foamed styrene board of the present invention can contain a mixture of other known resins, if necessary, as long as its characteristics are not lost. Preferred examples thereof include polystyrene and high-impact polystyrene obtained by radical polymerization,
Examples include polyphenylene ether, ABS, styrene-conjugated diene block copolymer and hydrogenated products thereof. In the composition constituting the extruded expanded styrene board of the present invention, the method of forming and processing the extruded expanded styrene board is not particularly limited. A known method for producing an extruded expanded styrene board can be used. For example, a nucleating agent such as talc or calcium carbonate and a formability modifier such as liquid paraffin are melted and mixed using an extruder in a styrene-based polymer, a foaming agent is press-fitted, and then extruded and foamed from a circular die. It can be manufactured by boarding.

As the foaming agent, hydrocarbons or halogenated hydrocarbons which are gaseous at ordinary temperature, such as industrial butane and dichlorodifluoromethane, or carbon dioxide gas and nitrogen gas can be used. The structure of the extruded expanded styrene board of the present invention varies depending on the purpose of use and cannot be particularly limited. However, in general, the thickness is 0.1 to 30 cm, preferably 0.2 to 20 cm.
cm, particularly preferably in the range of 1 to 10 cm. The expansion ratio is generally in the range of 2 to 100 times, preferably 10 to 80 times, particularly preferably 20 to 50 times. If the expansion ratio is low, the extruded expanded styrene board is heavy and the heat insulating property is undesirably reduced. If the expansion ratio is extremely high, the strength is notably reduced, which is not preferable.

The extruded foamed styrene board of the present invention can have a structure in which a thermoplastic resin film is laminated on one or both sides of the foam as required. This thermoplastic resin film may be a multilayer film including an adhesive layer and the like. The lamination may be on one side or both sides. Lamination of thermoplastic resin film improves appearance and printability,
It is useful for improving physical performance such as surface scratch resistance and rigidity. Examples of the thermoplastic resin used for the laminated thermoplastic resin film include a non-foamed styrene-based polymer and an olefin-based polymer. Specific examples of the non-foamed styrene-based polymer include polystyrene and impact-resistant polystyrene. Specific examples of the olefin polymer include polypropylene and polyethylene. Impact-resistant polystyrene is particularly preferably used because it has excellent impact resistance and can be easily laminated without any adhesive.

The impact-resistant polystyrene used for the thermoplastic resin film is particularly preferably one in which rubber particles are graft-polymerized with styrene to form islands, and polystyrene forms a so-called sea-island structure in which the polystyrene exists as sea.
The impact-resistant polystyrene has a weight-average molecular weight of preferably 100,000 or more as determined by gel permeation chromatography of a dissolved portion when dissolved in tetrahydrofuran.
500,000, more preferably in the range of 150,000 to 300,000, the contained rubber-like substance is preferably in the range of 3 to 8% by weight, and the weight average particle size of the dispersed rubber particles is preferably 1.5.
６6 μm. The thickness of the laminated thermoplastic resin film is generally in the range of 10 to 1000 μm. It is preferably in the range of 80 to 200 μm, particularly preferably in the range of 100 to 150 μm. If the thickness is less than 80 μm, wrinkles may be peeled off and swelled at the time of laminating a film or processing an extruded styrene board. On the other hand, if the thickness is more than 200 μm, the extruded expanded styrene board is heavy, and it is not preferable because it becomes an obstacle to processing such as cutting.

The extruded foamed styrene board of the present invention is usually stored or transported by stacking many sheets.
At this time, the board may cause blocking and may be damaged during peeling. Blocking can be prevented by applying silicone oil to the surface of the extruded foamed styrene board. When applying silicone oil, the silicone oil can be dispersed in water using an emulsifier and applied to the surface of the extruded foamed styrene board. However, a small amount of silicone oil has a small effect, and the one applied by rubbing or the like peels off and loses its effect. Therefore, a sufficient effect cannot be exhibited unless it is applied more than a certain amount.

When the thermoplastic resin film to be laminated is an impact-resistant polystyrene film, a material obtained by adding and mixing silicon oil to impact-resistant polystyrene in advance for the purpose of imparting lubricity, improving impact resistance and elongation is used. Can also. As a result, the same effect as when silicone oil is applied to the surface of the extruded foamed styrene board can be expected. In this case, the content is preferably in the range of 0.01 to 3% by weight, particularly preferably 0.1 to 1.5% by weight. If the content of the silicone oil is less than this range, the effect of addition is significantly reduced, and if the content is too large, the adhesion to the extruded expanded styrene board is significantly reduced, which is not preferable.

As a specific example of the silicone oil, there can be mentioned polydimethyl silicone oil. Polydimethylsilicone oil having a viscosity at 23 ° C. of 10,000 to 30,000 centistokes according to JIS K-2283 and a heat loss test at 150 ° C. for 24 hours of not more than 0.3% by weight is particularly preferably used. it can. The laminated thermoplastic film used is formed into a film by an extruder or the like. During film formation, the properties of the added oil determine the formability. If the viscosity is less than 10,000 centistokes, bleed-out is easy, and a large amount of volatile components are contained. If the bleed-out is excessively difficult, the amount of effective residual silicon on the surface is insufficient, and the above-mentioned effects are not sufficiently exhibited. The extruded expanded styrene board of the present invention can be preferably used for various applications in which the use of a conventional extruded expanded styrene board is known. In particular, it has a very low content of styrene monomer and styrene-based low molecular components, and has little volatilization or elution of organic compounds. , And for use as a core material for chemical tatami mats.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to Examples and Comparative Examples. However, these are only examples and do not limit the technical scope of the present invention in any way. (Production Method 1 of Styrene Polymer) Capacity 2 with Stirrer
A first reaction vessel, which is a complete mixing type of liter, and a second reaction vessel of a plug flow type having a capacity of 1 liter, provided with a stirrer, were connected in series. The temperature of both reactors was controlled at 80 ° C.
In a first reaction tank, a mixed liquid of styrene monomer and cyclohexane at a weight ratio of 50/50 as a polymerization solvent at 1.78 Kg /
Feed at the time flow rate. Separately, a hexane solution of n-butyllithium as an organic lithium initiator was fed to the same reaction vessel in an amount corresponding to 0.8 mmol per 100 g of the styrene monomer. The reaction solution flowing out of the first reaction tank was continuously passed through the second reaction tank by a plug flow. The conversion of the monomer into the polymer at the time of flowing out of the first reaction tank was 98% on average, and the conversion after passing through the second reaction tank was 99.99% or more. The anion active terminal was inactivated by adding methanol three times the amount of lithium to the obtained polymer solution. Thereafter, 0.01 g of an antioxidant was added to the polymer solution per 100 g of the polymer, and then the mixture was heated at 230 ° C. in a reduced pressure flushing tank to remove volatile components. Further, the remaining volatile components were removed through an extruder equipped with a reduced pressure vent at 230 ° C.

(Production Method 2 of Styrene Polymer) A first reaction tank which is a complete mixing type having a real capacity of 2 liters equipped with a reflux condenser and a stirrer, and a plug flow type having a capacity of 1 liter provided with a stirrer The second reactor was connected in series. A 50/50 weight ratio mixture of styrene monomer and cyclohexane (containing 3 wt% n-hexane) as a polymerization solvent was fed to the first reaction tank at a flow rate of 1.78 kg / hour. Also, n is an additional organolithium initiator.
A solution of -butyllithium in cyclohexane was fed to the reactor in an amount corresponding to 8 mmol per 1 kg of styrene monomer. The pressure in the first reaction tank was set to normal pressure, and the heat generated during the polymerization was removed while refluxing cyclohexane in a reflux condenser. The temperature of the reaction solution is 81 ° C
It was almost stable. The temperature of the second reaction tank was controlled at 80 ° C.

(Production Method 3 of Styrene Polymer) In a 2-liter reactor equipped with a stirrer, 0.75
Kg of a styrene monomer, 0.75 kg of ethylbenzene as a polymerization solvent, and 0.57 mmol of n-butyllithium as an organolithium initiator are charged. Thereafter, when the temperature was gradually increased while stirring, the temperature was raised from about 50 ° C. due to internal heat generation, and the final temperature reached 131 ° C. Thereafter, the temperature was gradually lowered to 100 ° C., and the reaction was continued for a total of 1.5 hours. The processing conditions after the polymerization were the same as in Example 1. (Production method 4 of styrene polymer) The same operation as in Example 1 was carried out except that ethylbenzene was used as a polymerization solvent and the temperature of both reaction vessels was set at 122 ° C.

(Production Method 5 of Styrene Polymer) In a 2-liter capacity reactor equipped with a stirrer, 1.35 at room temperature was added.
Kg of a styrene monomer and 0.15 kg of ethylbenzene as a polymerization solvent are charged. Thereafter, the temperature was gradually increased while stirring, and thermal radical polymerization was carried out at 130 ° C. to 140 ° C. for 6 hours, and thereafter polymerization was continued at 160 ° C. for 2 hours. The processing conditions after the polymerization were the same as in Example 1. Table 1 shows the molecular weights of the styrene polymers obtained by Production Methods 1 to 5 and the content of the low-molecular components contained therein.

[0038]

[Examples 1 to 4],

Comparative Examples 1-4 Using the styrene-based polymer obtained by the above-mentioned production methods 1-5, talc as a nucleating agent, and liquid paraffin according to conditions were added, and the mixture was introduced into a first-stage extruder.
After thermoplasticization at 20 ° C., butane was impregnated at about 8% by weight and impregnated. Next, the mixture was fed into a second-stage extruder, and the temperature adjusted to a viscosity suitable for foaming was extruded from a die at about 130 ° C. to produce an extruded foamed styrene board. The average thickness of the extruded expanded styrene board was set to about 5.2 mm, and the average magnification was set to about 30 times. After the obtained extruded expanded styrene board was sufficiently cured, its performance was evaluated according to the following criteria. Table 2 shows the results.

Criteria for Performance Evaluation 1) Foaming Characteristics ：: Size of bubbles is uniform and independent. Δ: Bubbles are slightly non-uniform in size, and partially continuous bubbles are present. ×: The size of the bubbles is non-uniform, and some continuous bubbles are slightly present. 2) Surface state The surface state of the extruded styrene expanded board was evaluated by visual observation. ：: The surface is beautiful and rich in smoothness. ×: Surface roughness occurred 3) Rigidity The extruded foamed styrene board surface was evaluated by drawing a line at a hardness of 2B with a load of 0.2 kg and a speed of 2 cm / sec, and visually observing the pencil. ：: A dent is seen in the pencil mark, but almost no tearing of the epidermis is observed. ×: Pencil marks were dented, and remarkable tearing of the epidermis was observed.

4) Strength The extruded expanded styrene board was bent at 90 ° C., and the strength was evaluated based on the state of cracks in the bent portion. ：: The trace of bending remains wrinkled, but no crack was observed. X: Cracks were remarkably observed on the surface of the bent mark. 5) Measurement of Organic Compound Volatility The extruded expanded styrene boards obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were crushed, and a petri dish containing 100 g of the styrene board and 20 g of heat-purified silica gel was put into a desiccator. Was. The lid was closed and left at 25 ° C. for 1 week. The organic compound volatilized from the pulverized product of the extruded expanded styrene board during standing is adsorbed on the silica gel.
Thereafter, the silica gel was taken out, desorbed with acetone, the amount of the adsorbed organic compound was measured by gas chromatography, and converted to the amount adsorbed on 20 g of silica gel. Extruded expanded styrene board 1
As the amount of the organic compound volatilized from 00 g, (the amount of the organic compound adsorbed on 20 g of silica gel (g)) / 100 g × 1
And 0 ^6, was ppm conversion. Detection limit of measurement is 1ppm
Met. ：: The amount of volatile organic compounds is less than the detection limit. X: It was in the range of 1 to 15 ppm. The evaluation results are shown in Table 2.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

Example 5 475D (manufactured by Asahi Kasei Corporation) having a weight-average molecular weight of about 230,000, a rubber content of about 6%, and an average rubber particle diameter of 4 μm was used as an impact-resistant polystyrene film. The thermoplastic obtained at 220 ° C. was extruded from a die and extruded to a thickness of about 100 μm. The obtained impact-resistant polystyrene film was laminated on the extruded styrene foam board obtained in Example 1 by heating. As a result, an extruded foamed styrene board having a beautiful laminated structure and completely adhered was obtained.

Example 6 Silicon oil (manufactured by Toshiba Silicon Co., Ltd.) was added to the above 475D as an impact-resistant polystyrene film:
TSF451-12500) was introduced into an extruder and thermoplastically extruded at about 220 ° C. from a die and extruded to a thickness of about 100 μm. The obtained impact-resistant polystyrene film was laminated on the extruded styrene foam board obtained in Example 1 by heating. As a result, an extruded foamed styrene board having a completely bonded laminated structure was obtained.
In addition, the surface was beautiful, and a state rich in lubricity could be achieved.

[0044]

The extruded styrene board of the present invention is characterized in that it has excellent resin properties such as foamed state, surface state, rigidity and strength, and that no volatile organic compound is observed.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoshi Kawakami 3-13-1, Ushidori, Kurashiki City, Okayama Prefecture Inside Asahi Kasei Corporation (72) Inventor Hirofumi Shirai 3-13-1, Utsudori, Kurashiki City, Okayama Prefecture Asahi Kasei Corporation F-term in the formula company (reference) 2E001 DD01 HD09 4F074 AA00 AA32 AA98 AB01 BC11 BC12 CA22 CE02 DA02 DA20 DA23 DA32 DA58 4J002 AE042 BC021 BC031 BC051 DE136 DE236 DJ016 DJ046 FD206 GL00

Claims (6)

[Claims] 1. A composition comprising (a) 100 parts by weight of a styrene-based polymer, (b) 0.1 to 5.0 parts by weight of a nucleating agent, and (c) 0 to 3.0 parts by weight of liquid paraffin. (A) the styrene-based polymer is a polymer mainly composed of styrene-bonded units obtained by an anionic polymerization method using an organolithium initiator, and has a weight average molecular weight of 5 Styrene-based low molecular weight component having a molecular weight of 140 to 400,
The styrene-based low molecular weight component comprises a styrene oligomer component and a non-styrene oligomer component. ) Is 1000 ppm
Extruded styrene board, characterized in that the amount of the non-styrene oligomer component is less than 500 ppm. 2. The extruded foamed styrene board according to claim 1, wherein (a) the molecular weight distribution (Mw / Mn) of the styrenic polymer is in the range of 1.5 to 5.0. 3. The extruded foamed styrene board according to claim 1, wherein (a) the styrene-based polymer contains less than 500 ppm of a styrene monomer. 4. The extruded foamed styrene board according to claim 1, wherein (a) the residual hydrocarbon solvent contained in the styrene-based polymer is less than 1000 ppm. 5. A heat insulating material using the extruded expanded styrene board according to claim 1. 6. A tatami mat core material using the extruded styrene board according to claim 1. Description: