JPS6029744B2 - Method for producing flame-retardant styrenic resin foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a flame-retardant styrenic resin foam.

It is already known that a foaming agent and an elutriation agent are added to styrene resin, the mixture is put into an extruder, and the mixture is extruded from a nozzle attached to the tip of the extruder to produce a resin foam. There is.

In this case, a volatile organic compound having a boiling point lower than the softening temperature of the resin was often used as the blowing agent. Examples of volatile organic compounds include aliphatic hydrocarbons such as propane and butane, halogenated aliphatic hydrocarbons such as methyl chloride, ketones such as acetone, and methyl acetate. Various compounds such as esters were used. Various compounds have also been proposed as flame retardants. Examples include antimony trioxide, various phosphates, and various halogen compounds. Among these, unless antimony trioxide is used in a certain amount, the flame retardant effect will not be fully exhibited. However, antimony trioxide works poorly as a filler for styrenic resins, so if a large amount of antimony trioxide is used, the physical properties of the styrene resins will deteriorate. Therefore, the use of antimony trioxide was considered undesirable. In particular, if a large amount of antimony trioxide is used, foamability is inhibited, making it impossible to obtain a good foam. Various phosphates are not preferred as flame retardants for styrenic resins, since they are also harmful as fillers in the same way as antimony trioxide. The brood retardant, which does not exhibit properties as a filler, is a solid organic compound containing a halogen element. Therefore, various solid halogenated organic compounds have been proposed as brood retardants. Tokuko Showa 5
4-25058 discloses that three types of solid halogenated organic compounds, a halogenated aromatic aliphatic ether, a halogenated aliiso group compound, and a halogenated aromatic compound, are added to a thermoplastic synthetic resin in a certain amount. It tells you what to mix in proportions.

However, this publication does not target foams. Therefore, the composition recommended in this publication cannot be applied as is to the production of styrenic foams.
This is because, according to the results of the present inventor's actual attempts, a good foam could not be obtained using the mixing ratio recommended in this publication. This is because the bubbles were not uniform and fine, the bubbles lacked thermal stability, and extrusion instability occurred. On the other hand, JP-A-53-86
Publication No. 63 describes a method of extruding a styrene-based resin to make a foam, and a method of converting the foam into a foam.

According to this publication, 2,2-bis(4-allyloxy-3
, 5-difuromophenyl) propane and an alkaline compound are said to be suitable for making styrenic resins flame retardant. However, according to the results of additional trials by this inventor, although this method does not significantly reduce the thermal stability of the resin, it does not provide good flame retardance, and the bubbles produced are coarse. I didn't tell them that I could get a foam that looked good. The inventor has developed a flame retardant that provides good flame retardancy to the styrene resin without impairing the properties of the styrenic resin when extruded and foams the styrene resin, and that allows the resin to be foamed uniformly and finely. I explored.

To this end, we conducted various experiments using solid halogenated organic compounds known as key combustion agents. the result,
Those with excellent properties as flame retardants have a strong tendency to impair the thermal stability of styrenic resins, and conversely, those with good thermal stability have poor properties as flame retardants. I learned something. In addition, I learned that among solid halogenated organic compounds, brominated organic compounds are the most suitable. Furthermore, I learned that the property of uniformly and finely foaming a styrene resin cannot be predicted from the chemical structural formula of a flame retardant, but can only be understood by actually foaming it. This inventor used a volatile organic compound with a boiling point lower than the softening temperature of styrenic resin as a foaming agent, and a solid brominated organic compound as a combustion agent to extrude and foam the same. found that when a small amount of lead stearate was added to this, uniform and fine bubbles were generated, and flame retardance, thermal stability, and extrusion stability were improved. In addition, when using a volatile organic compound as a blowing agent and adding lead stearate to it for extrusion foaming, the inventor also found that among the solid halogenated organic compounds added as a flame retardant, bromine was included. It has been found that it is suitable to use 1 to 2 parts by weight of the solid compound per 10 parts by weight of the resin. Among the bromine-containing solid compounds, hexabromocyclododecane, 2,2-bis(4-allyloxy-3,5-dibromophenyl)p. Pan, and 2,4,6-tribromophenylallylable were found to be suitable. Furthermore, the inventor found that it is effective to mix these retardants in a specific ratio, and in particular, the mixing ratio is 2,2-bis(2,2-bis(
It has been found that a ratio of 4-allyloxy-3,5-dibromophenyl)propane and/or 2,4,6-tribromophenylallyl ether of 1 to 0.1 parts by weight is suitable. . This invention was made based on these findings. This invention supplies a mixture of a styrenic resin, a blowing agent, and a combustion agent to an extruder,
In the method of manufacturing a resin foam by extruding it from a die, one to three parts of a volatile organic compound having a boiling point lower than the softening temperature of the styrene resin is added as a blowing agent to 10 parts by weight of the styrene resin. 1 part by weight or 2 parts by weight of an organic solid compound containing bromine as a bromine retardant, and 0.1 part by weight or 2.0 parts by weight of lead stearate, and a mixture of these is mixed. The present invention relates to the production of flame-retardant styrene resin foam, which is characterized by extruding it from a die. Next, detailed matters regarding this invention method will be explained separately for each requirement.

In the method of this invention, styrene resin is used, but styrenic resins include not only styrene and its derivatives polymerized alone, but also styrene and its derivatives polymerized with other monomers. It also includes polymers obtained by polymerizing with and mixtures of these alone or copolymers with other polymers.

Examples of styrene derivatives include Q-methylstyrene, chlorostyrene, and dimethylstyrene. The styrene copolymer is, for example, a copolymer of styrene and divinylbenzene, methyl methacrylate, acrylonitrile, butadiene, or the like. The mixture of polymers is, for example, an ABS resin, that is, a polymer mixture of acrylonitrobutadiene-styrene. As the blowing agent, a volatile organic compound having a boiling point lower than the softening temperature of the styrene resin is used.

This compound is already known. These compounds can be broadly classified into aliphatic hydrocarbons, aliphatic halogenated hydrocarbons,
Contains aliphatic ketones and aliphatic esters.
Examples of hydrocarbons are propane, butane, bentane, etc. Examples of aliphatic halogenated hydrocarbons are methyl chloride, methylene chloride, Freon 11, Freon 1
2, Freon 114. Aliphatic ketones are, for example, acetone, and aliphatic esters are, for example, methyl acetate. These may be used alone or in combination. The reason why a volatile organic compound is used in the method of this invention is that such an organic compound is stable, easily mixed into the styrenic resin, and foams the styrenic resin well.

This foaming agent is based on 100 parts by weight of styrene resin.
It is used in a ratio of 1 part by weight to 3 parts by weight. This blowing agent is preferably press-fitted into the resin in an extruder, but
It may be impregnated into the resin before being put into the extruder. An organic solid compound containing bromine is used as the chick retardant.

The reason why an organic solid compound containing bromine is used is that such a compound has been recognized to have the best ability to burnish a styrene resin among organic compounds containing a halogen element. There are various solid organic compounds that contain bromine. The three types of brominated aromatic aliphatic ethers, brominated alicyclic compounds, and brominated aromatic compounds described in Japanese Patent Publication No. 54-250 are all organic solid compounds containing bromine. include. There are many kinds of these, but the best one is hexabromocyclododecane (hereinafter referred to as HCD).
), 2,2-bis(4-allyloxy-3,5-dibromophenyl)propane (hereinafter referred to as BAP), 2,4,6-tribromophenylallyl ether (
Hereinafter, this will be referred to as TPA). Especially HCD and B
The effect is remarkable when used in combination with AP or TPA. That is, the effect is remarkable when two types of brominated solid compounds are used together, and HCD is always used as one of them, and either BAP or TPA is used as the other. . Among these, BAP and TPA may be used simultaneously. When used together, H
The amount of BAP or TPA or BAP for the amount of CD used
It is preferable that the ratio of the total amount of TPA and TPA is within a range of 1 to 1 for the former to 0.1 for the latter. Further, the proportion of these brood retardants used is within the range of 1 to 2 parts by weight per 100 parts by weight of the resin. HCD is made up of three brominated butadiene molecules bonded together to form one carbon atom.
It is a compound with a structural formula in which two rings form one ring.

HCD is a powder with a melting point of 18yo and a decomposition point of 21ro, and is slightly soluble in acetone, benzene, etc. at room temperature, but is insoluble in methanol, carbon tetrachloride, etc. When HCD is mixed with a single styrene resin, it does not reduce the thermal stability of the styrene resin, does not inhibit the foamability of the styrene resin, and generates uniform, fine bubbles. . However, HCD does not significantly improve the flame retardancy of styrenic resins. Therefore, a good flame-retardant foam of styrene resin cannot be obtained by simply mixing HCD into styrene resin. BAP is a compound with an ether structure formed by condensation of an aliphatic alcohol and a brominated aromatic alcohol, and belongs to brominated aromatic aliphatic ethers.

BAP is a powder with a melting point of 11,800 and a decomposition point of 22000, and is soluble in acetone, benzene, etc. at room temperature.
It is slightly soluble in methanol and carbon tetrachloride at room temperature. If BAP is simply mixed into a styrenic resin, it will impart flame retardancy to the resin, but it will greatly impair thermal stability. BAP also has a negative effect on the foaming of styrenic resin, making the bubbles coarser. Therefore, just by mixing BAP with styrene resin, a good foam cannot be obtained. However, when lead stearate is added to this, the thermal stability becomes good, the cells become uniform and fine, and a good foam is obtained. TPA, like BAP, is a compound with an ether structure created by condensation of an aliphatic alcohol and a brominated aromatic alcohol.

TPA has a melting point of 78 qo and a decomposition point of 1 unit. 0 powder, which dissolves well in acetone, benzene, carbon tetrachloride, etc. at room temperature, but only slightly dissolves in methanol.

When TPA is mixed into a styrenic resin, it imparts flame retardancy but deteriorates thermal stability. However, the degree of deterioration of thermal stability is not as great as that of BAP.
Furthermore, TPA does not have much of an adverse effect on the foaming of styrenic resin. However, since TPA deteriorates the thermal stability of the resin, it does not result in a good foam. However, when lead stearate is added to this, the thermal stability is improved and a good foam can be obtained. In this way, HCD,
BAP and TPA each have their own advantages and disadvantages when individually mixed into styrene resin, and it has not been possible to provide a styrenic resin foam with good flame retardancy.

However, in this case, lead stearate was added to the resin at a rate of 0.1%.
When added in an amount of 2 to 2% by weight, the above drawbacks are surprisingly improved and a styrenic resin foam with good flame retardancy can be obtained. In particular, BAF and/or TPA in HCD
B.
When AP or TPA is set to 0.1 to 1 and the total amount of these key flame retardants to the resin is set to 1 to 2% by weight, it has better thermal stability, uniform fine foaming, and flame retardancy. A sufficient amount of foam can also be obtained. In the method of this invention, lead stearate is mixed.

Lead stearate is known as a stabilizer for pinyl chloride resins, and has been mainly used as a mixture in vinyl chloride resins. However, lead stearate has not been mixed into styrenic resins together with these key fuel agents. However, when lead stearate is mixed into styrene-based resin together with the above-mentioned scale retardant, it improves the thermal stability of the resin, further improves flame retardancy, and makes it more uniform and finely foamed, making it difficult to extrude. The stability will be improved, thus giving a better flame retardant foam. Such effects were not seen with zinc stearate and barium stearate. To mix lead stearate into styrenic resin, mix the lead stearate with the styrenic resin elsewhere before putting it into the extruder, and then put it into the extruder and mix it uniformly. .

Similar methods can be explored to incorporate key combustion agents such as HCD, BAP or TPA into styrenic resins.

However, when the infant retardant is mixed in this manner, the retardant is often not dispersed as uniformly in the resin as desired. This is because the retardant melts at a lower temperature than the resin, so it already melts near the hopper of the extruder and adheres to the hopper wall, screw groove, etc.
To prevent this, use flame retardants, especially BAP.
It is preferable to heat and melt TPA and press it into the extruder from the middle, or dissolve BAP and/or TPA in a volatile organic compound as a blowing agent and press it together with the blowing agent from the middle of the extruder. . As a blowing agent for this purpose, it is necessary to use one that dissolves BAP and/or TPA well, and specifically, methyl chloride, methylene chloride, ethyl chloride, Freon 11, etc. are suitable. According to this method, a styrenic resin foam can be obtained which is uniformly and finely foamed, has good heat resistance, good flame retardancy, and also has good extrusion stability.

This foam foams uniformly and finely and has good heat resistance, so it can be used as a structural material and insulation material in the same way as conventional styrene resin foams.It also has good flame retardancy, so it is widely used as a construction material. Can be used. In this respect, the method of this invention has great practical value. Next, the method of the present invention will be explained with reference to Examples and Comparative Examples.

Hereinafter, parts simply refer to parts by weight. In addition, the flame retardance and thermal stability of the products are measured in the examples, and the measurement methods are as follows. Flame retardancy test: JISA
It was carried out according to 9511.

That is, a test piece with a thickness of IQ, a width of 25 mm, and a length of 20 mm was cut from a cylindrical foam, and after being left at room temperature for one week,
This was held diagonally at a 45 degree angle and burned with a candle. The number of tests was fixed at 1, the average combustion time (seconds) was set as X, and the variation R was determined. Those with a smaller value of x within 3 were considered good, and the evaluation was divided into four stages. Thermal stability test: Cut out the foam for 3 days, compress it, put it in a glass test tube with a metal piece, heat it in an oil bath at 200℃ for 10 minutes, leave it at room temperature for 2 days, and then check the color tone of the resin. The changes and the state of mirror formation in the metal pieces were investigated and used as a standard for thermal stability.

The change in color tone and the state of rust occurrence were comprehensively divided into four grades and evaluated. Carbon tool steel was used as the metal piece. Example
1 Polystyrene resin (Sumitomo Chemical Co., Ltd. Esbrite 7M)
10 Ikari Oriko, tin stabilizer (Nitto Kasei K.KTVS#N
200) and then 0.5 part of finely powdered talc and BAPI. Moribe and 0.2 part of lead stearate were added, and the mixture was placed in a super mixer and mixed well, and these additives were uniformly spread on the surface of the resin to form a blend.

This mixture was put into an extruder, and a blowing agent injection port was provided in the middle of the extruder, and the blowing agent was press-injected from there.

As a blowing agent, dichlorodifluoromethane (hereinafter referred to as F
12) and methyl chloride (hereinafter referred to as MC) in a ratio of 1:1 to styrene resin 10
It was press-fitted at a ratio of 12 parts to the anchor. The extruder has an inlet side of 180~200oo and an outlet side of 100~1200oo.
The temperature of the resin was 105 to 11,500, and the resin was extruded through a cylindrical hole with a diameter of 4 bars in the die.

The extruded resin was foamed uniformly and finely, and had good flame retardancy and thermal stability.

The density of the product thus obtained was 39.4 kg/, and the X of the flame retardant test was 1. The FR was 2.4, and the flame retardancy was recognized as excellent. Further, in the thermal stability test, slight discoloration of the resin was observed, but no metal corrosion was observed, and the test results were generally good. Moreover, the air bubbles were uniform in the range of 0.4 to 0.5. When these results were combined, the product was recognized to be good. Example 2 0.4 parts HCD and 0.4 parts BAP as flame retardants
and 0.4 part of TPA were used, except that the same amount as in Example 1 was used.

The obtained product has a density of 34.5k9/〆 and foams well, the size of the bubbles is 0.2 to 0.4 cells, and in the flame retardant test, X is 1.7 and R is 2.2. In the thermal stability test, no discoloration of the resin or metal corrosion was observed, and it was recognized as being good.

When these results were combined, the product was recognized to be good.
Example 3 As a flame retardant, 1. Foundation HCD and 0.2 part TP
It was carried out in exactly the same manner as in Example 1 except that A was used.

The obtained product has a density of 42.1k9/m and foams well.
The size of the bubbles is on the 0.3 to 0.4 side, and in the flame retardancy test, it was recognized as good with X of 3.0 and R of 5.2, and in the thermal stability test, the discoloration of the resin was comparable to that of metal. No corrosion was observed and the product was considered to be in good condition. When these results were combined, the product was recognized to be good. Example 4 As a flame retardant, 1. HCD of Ikaribe and BA of 0.2 parts
Example 1 was carried out in exactly the same manner as in Example 1, except that this flame retardant mixture was melted and press-fitted into the resin.

The obtained product has a density of 45.4k9/m and foams well.
The size of the bubbles is 0.3 to 0.4 willow, and in the flame retardancy test, it was recognized as excellent with X of 2.7 and R of 2.2, and in the thermal stability test, the discoloration of the resin was comparable to that of metal. No corrosion was observed and the product was considered to be in good condition.

Combining these results, the product was recognized as excellent.
Comparative Example 1 A test was carried out in exactly the same manner as in Example 1 except that 1.2% of BAP was used as the retardant and lead stearate was not used at all.

The obtained product had a density of 45.8k9/m, foamed well, and the size of the bubbles was coarse on the 0.4 to 0.6 side, and in the flame retardancy test, × was 0.3 and R was 1.2, which was excellent; however, in the thermal stability test, the resin was judged to be extremely poor, with significant discoloration and corrosion.

Therefore, when these results were combined, the product was judged to be extremely poor. Comparative Example 2 0.4 parts of HCD and 0.4 parts of BAP as combustion enhancers.
Example 1 was carried out in exactly the same manner as in Example 1, except that 0.4 part of TPA was mixed and lead stearate was not used.

The obtained product had a density of 37.8 k9/m and was well foamed, but the bubble size was 0.4 to 0.6 cm and was coarse.

Further, in the flame retardancy test, X was 1.3 and R was 2.8, which was recognized as excellent, but in the thermal stability test, no corrosion of the metal was observed, but discoloration of the resin was observed, and it was judged to be poor. Therefore, the overall judgment was that it was extremely poor. Comparative Example 3 Conducted in exactly the same manner as in Example 1, except that 1.2 parts of BAP alone was used as a flame retardant and 0.2 parts of magnesium oxide was used instead of lead stearate. did.

The obtained product had a density of 36.9k9/m, was well foamed, and had coarse bubbles with a size of 0.5 to 0.7 cells.

In the flame retardancy test, X was 5. On the other hand, R was 8.0 or more, which was extremely poor, and although no metal corrosion was observed in the thermal stability test, some discoloration of the resin was observed, which was considered to be poor. Therefore, it was judged to be bad overall. Comparative example 4
0.4 part HCD and 0.4 part BA as flame retardants
Example 1 was carried out in exactly the same manner as in Example 1, except that P and 0.4 part of TPA were used, and lead stearate was not used, and 0.2 part of potassium phosphate was used instead.

The obtained product has a density of 36.0k9/m and no bubbles.
．． The size was on the 3 to 0.5 side and foamed well.

In the flame retardancy test, X was 1.5 and R was 2.4, which was recognized as excellent, but in the thermal stability test, there was some discoloration of the resin and significant corrosion of the metal, so it was recognized as poor. It was done.
Therefore, it was judged to be bad overall. Comparative Example 5 0.4 part of HCD and 0.4 part of BA as a retardant
Example 1 was carried out in exactly the same manner as in Example 1, except that P and 0.4 part of TPA were used, and lead stearate was not used, and 0.2 part of zinc stearate was used instead.

The obtained product has a density of 36.4 kg/〆
Although foaming occurred, the bubbles were coarse and had a size of 0.4 to 0.6 mm.

In the flame retardancy test, X was 4.6 and R was 8.0, which was recognized as poor. Further, in the thermal stability test, although no corrosion of the metal was observed, the discoloration of the resin was significant and was recognized to be poor. Therefore, it was judged to be bad overall. Comparative Example 6 In this comparative example, 0.4 parts of HCD and 0.4 parts of HCD were used as elutriation agents.
．． Example 1 was carried out exactly as in Example 1, except that 4 parts of BAP and 0.4 parts of TPA were used, and lead stearate was not used and 0.2 parts of barium stearate was used instead.

The obtained foam had a density of 39.6k9/m, and the cell size was 0.5 to 0.6 cells, making it coarse.

In the thermal stability test, although some discoloration of the resin was observed, no corrosion of the metal was observed and it was recognized as being good, but in the flame retardancy test, X was 4.0 and R was 7.0. recognized as bad. Therefore, it was judged to be bad overall. Comparative Example 7 In this comparative example, 1. Ikaribe's HCD and
0. The foam obtained was carried out in exactly the same manner as in Example 1, except that TPA of the same type was used and lead stearate was not used. The resulting foam had a density of 35.9k9/m, and a cell size of 0. It was good with 3 to 0.4 legs.

In the flame retardancy test, it was recognized as excellent with X of 2.2 and R of 2.4, but in the thermal stability test, both discoloration of the resin and corrosion of the metal were slightly observed, and it was recognized as poor. Therefore, it was recognized as bad overall. Comparative Example 8 In this comparative example, 1. Ikaribe's HCD and 0
．． It was carried out in exactly the same manner as in Example 1, except that BAP of the cluster was used and lead stearate was not used.

The obtained foam had a density of 43.0k9/m2 and was well foamed, but the cell size was 0.4 to 0.5 feet and was somewhat coarse.

Claims (1)

[Scope of Claims] 1. A method for producing a resin foam by supplying a mixture of a styrene resin, a foaming agent, and a flame retardant to an extruder and extruding it from a die, wherein 1 to 30 parts by weight of a volatile organic compound having a boiling point lower than the softening temperature of the styrene resin as a blowing agent, and 1 to 2 parts by weight of an organic solid compound containing bromine as a flame retardant. A method for producing a flame-retardant styrenic resin foam, which further comprises mixing 0.1 to 2.0 parts by weight of lead stearate and extruding the mixture from a die. 2. Organic solid compounds containing bromine include hexabromocyclododecane, 2,2-bis(4-allyloxy-3,5
2. The method according to claim 1, using 2,4,6-tribromophenyl allyl ether or a mixture thereof. 3 For 1 part by weight of hexabromocyclododecane, 2,
A patent claim in which 2-bis(4-allyloxy-3,5-dibromophenyl)propane and/or 2,4,6-tribromophenyl allyl ether are mixed in a proportion of 1 to 0.1 part by weight. The method described in Item 2 of the scope. 4 2,2-bis(4-allyloxy-3,5-dibromophenyl)propane and/or 2,4,6-tribromophenyl allyl ether are heated and melted, or the boiling point is 6.
The method according to claim 2 or 3, wherein the method is dissolved in a volatile organic liquid at 0° C. or lower and pressurized into an extruder from the middle.