JPS5835615B2 - Improved styrenic polymer extrusion foam manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing an extruded flame-retardant styrene polymer foam, and more specifically, the present invention relates to a method for producing an improved extruded flame-retardant styrene polymer foam, and more specifically, the density distribution in the cross section of the extruded foam original plate is made more uniform, and the resulting foam is improved. This invention relates to a method for producing a flame-retardant styrenic polymer extruded foam with improved compressive strength, repeated compressive strain characteristics, and heat insulation performance.

Styrenic polymer extruded foam is, for example,
No. 2690, Special Publication No. 31-5393, Special Publication No. 36-2
As described in No. 2276, U.S. Patent No. 3,188,295, etc., the manufacturing method thereof is well known, and its insulation, durability, hygiene,
Recognized for its characteristics such as ease of handling, it is used as insulation material in all kinds of buildings, from freezers and storage rooms to hotels, hospitals, offices, factories, and general residences, and plays a major role in saving energy and improving livability. is fulfilled.

However, when using styrene polymer foam for building materials, the combustibility of the foam becomes a problem, and JISA 951
As stipulated in Article 1, foams are required to be self-extinguishing or flame retardant from the viewpoint of fire prevention.

Usually, a flame retardant is added to impart flame retardancy to a foam, but at this time, in order to reduce the cell diameter of the foam (in order to maintain a constant density and improve the insulation properties of the foam, it is necessary to add a flame retardant). The diameter must be made sufficiently small.

) When ordinary nucleating agents such as calcium silicate, diatomaceous earth, and silicone oil, which are most commonly used, are used, the bubble diameter can be controlled, but there is a problem in that flame retardancy is significantly impaired.

This problem was solved in Japanese Patent Publication No. 36-22276 and US Pat. It is said that it is not easy to obtain a foam with a sufficiently small diameter, and that this can be achieved when an indigo compound and a copper phthalocyan pigment are used as nucleating agents.

The present invention is a further improvement to the above-mentioned conventional method for producing extruded flame-retardant styrene polymer foam. When we went back and examined the contents of the polymer used for foaming, we found that when we used a polymer that met specific requirements that had not been seen before, the cross-sectional density distribution of the resulting extruded foam original plate was The present invention was accomplished by discovering that the foam can be made more uniform, and the compressive strength, repeated compressive strain characteristics, and heat insulation performance of the foam can also be improved.

A little explanation will now be given on the practical effects brought about by the uniform density distribution and the improvement of repeated compressive strain characteristics in the present invention.

Generally, a styrenic polymer foam original plate obtained by an extrusion foaming method has density irregularities in its cross section, with the density being lower in the center and higher in the outer periphery.

In a styrene polymer foam, if the density is in a sufficiently small range (20 to 50 kg/m'), the lower the density, the poorer the insulation performance (higher thermal conductivity) and the weaker the mechanical strength.

Therefore, when trying to manufacture a target product with certain heat insulation performance and mechanical strength, the physical properties of the lowest density part of the foam base plate, that is, the center of the base plate, are the target product, so the properties of the peripheral area caused by density unevenness are reduced. High density areas will be over-quality.

Therefore, if the minimum density can be kept the same and the density distribution can be made more uniform, the cost can be reduced by the amount corresponding to the reduction in excess portion brought about by uniformization.

Especially in the case of mass-produced type, the economic effect is extremely large.

In addition, flame-retardant styrene-based polymer extruded foam original plates are used in large quantities as they are or cut into thin pieces and laid on the floor or as core material for tatami mats. If this is improved, the problem of distortion in parts that are repeatedly subjected to stress during long-term use will be resolved, and the advantage will be that the pressure sensation will not change.

Therefore, the present invention provides a styrene-based material that is imparted with flame retardancy and has a controlled cell diameter by containing an appropriate amount of a flame retardant and a nucleating agent consisting of at least one of an indigo compound, a copper phthalocyan pigment, and an anthraquinone pigment. When producing an extruded polymer foam, a styrenic polymer containing 0.3% by weight or less of styrene monomer and 0.5 to 1.5% by weight of styrene triplet is used. The present invention relates to an improved method for producing extruded styrenic polymer foam.

The contents of the present invention will be explained in detail below.

The important requirements of the present invention are (a) the content of styrene monomer is 0.3% by weight or less;
b) The content of styrene trimer is 0.5 to 1.5% by weight,
Polymers in the range may be used.

The reason for this is that if the styrene monomer content exceeds 0.3% by weight, the strength and repeated compressive strain characteristics of the foam will not be improved.

Furthermore, even if the styrene monomer content is 0.3% by weight or less, if the styrene triplet content is 0.5% by weight or less, a sufficient density uniformity effect cannot be observed;
When the amount exceeds 1.5% by weight, the practical heat resistance properties of the resulting foam actually deteriorate.

Heat resistance here is different from the heat resistance of the resin itself, and refers to the asphalt heat resistance when the foam is adhered to the building frame with asphalt. It was evaluated.

When the asphalt heat resistance decreases, the degree of melting deformation, foam rupture, and decrease in foam volume of the foam cell membrane increases, making asphalt welding work difficult, and the accuracy after welding is poor, and the adhesive strength decreases. .

Such a phenomenon becomes noticeable when the content of styrene trimer exceeds 1.5% by weight.

When a flame retardant and nucleating agent are added to a styrenic polymer and extruded into foam, part of the flame retardant and/or nucleating agent changes during melt extrusion, resulting in a decrease in the strength of the resulting foam. However, by reducing the amount of styrene monomer with chemical double bonds contained in the polymer used in the present invention, the strength of the resulting foam is firstly improved; When the appropriate amount of polymer is present in the foaming melt, the melt flow region suitable for foaming is expanded, which contributes to uniform density distribution, and at the same time, the polymer during foaming becomes sticky, improving the elasticity of the cell walls. However, as a result, it is estimated that the strength of the foam is further improved, the repeated compressive strain characteristics are improved, and the heat insulation performance is also improved.

In addition, research conducted by the present inventors has confirmed that there is no significant difference in the content of styrene monomer and styrene trimer between the base polymer and the content after processing and foaming the base polymer.

The method of the present invention, for example, first takes into account the monomer polymerization method/conditions and polymer purification method/conditions from conventionally known styrenic polymer production methods, and selects styrene monomers of 0.3% by weight or less and styrene trimers. A polymer having a content of 0.5 to 1.5% by weight is selected, or polymers having different contents are appropriately mixed and adjusted, and this is used as a base polymer.

Next, for example, a flame retardant and a nucleating agent are premixed with the base polymer, this mixture is melt-mixed in an extruder, a blowing agent is injected into the molten mixture, and the mixture is further kneaded. The mixture is extruded from a die at room temperature under atmospheric pressure and foamed to form a foam.

The flame retardants used in the present invention include aliphatic hydrocarbon and aromatic hydrocarbon compounds that impart flame retardancy to the polymer;
In particular, bromides and their derivatives, or bromides of polyalkyl esters and ethers.

According to research by the present inventors, the decomposition temperature is 25% for styrene polymer foams with a density of 100:9/m or less.
A rogen-containing flame retardant having a temperature of 0° C. or lower is suitable, and a foam with stable flame retardancy, mechanical properties, and coloring properties can be obtained.

Additionally, examples of such flame retardants include tetrabromodecane (decomposition temperature 150°C), pentabromoethylbenzene (decomposition temperature 150°C),
0°C), tetrabromobisphenol A (210°C),
Tris (4-allyloxy-3,5-cyglomophenyl)
Examples include propane (195-198°C) and pentabromomonochlorocyclohexane (230-235°C).

The amount of these flame retardants added is about 0.5 to 1 of the amount of polymer used.
0% by weight, and these are normally fed into the extruder together with granular polymers, nucleating agents, etc., but they can also be added and mixed into the heated and plasticized melt at any point before the extrusion foaming zone. good.

Nucleating agents that are essential in the present invention include indigo compounds and copper phthalocyanine pigments, which have the ability to adjust the cell diameter without impairing the flame retardancy of the foam obtained even when the above-mentioned flame retardants are added. are listed as known.

However, according to the research of the present inventors, in particular, the color index (American Association of Textile Chemistry and Coloris
ericanAssociation of Te
xtile Chemists and Colori
sts) published classification: Bat Blue 1 (indigo compound) and Pigment Blue 15:1.15:2.15:3
．． 15:4 (copper phthalocyan pigment)
and Solvent Blue 35.83. as a new nucleating agent.
105 (both are anthraquinone compounds) provides flame-retardant styrenic polymer foam with excellent blue coloring properties and repeatability (ability to reuse recovered raw materials) without impairing flame retardancy. I discovered that.

These above-mentioned nucleating agents are 0.0
It is used in a proportion of 0.01 to 3% by weight.

Among these, when these nucleating agents are used in a proportion of 0.02 to 0.5% by weight, the foam exhibits an excellent light blue color, which is not only favorable in terms of appearance color, but can also be used as a detection measure for the decomposition of flame retardants during extrusion foaming. I saw something and put it out there.

That is, it has been found that when the extrusion foaming conditions become severe, the degree of decomposition of the flame retardant increases, the flame retardant effect decreases, and at the same time the blue color fades or changes color.

This phenomenon can be used to detect and correct abnormal conditions during the production of extruded foam, and thus can be an extremely simple and useful means of process control.

The blowing agents used in the extrusion foaming of the present invention are volatile organic compounds known per se, such as propane, butane, pentane, hexane, heptane, styrene, imbutylene,
Examples include dimethyl ether, methyl ethyl ether, methyl chloride, monochlorodifluoromethane, and perchlorofluorocarbons.

Mixtures of two or more of these blowing agents may also be used.

The amount of blowing agent added is generally used in an amount of 0.05 to 0.5 gr molar ratio per 100 gr of starting polymer.

The styrenic polymer used in the present invention refers to a polymer containing styrene as a main component, but it may also be a styrene-based monomer such as di-α-methylstyrene, vinyltoluene, or chlorostyrene.

Copolymers copolymerized with monomers copolymerizable with the above styrene monomers, such as acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, maleic anhydride, acrylamide, vinylpyridine, acrylic acid, methacrylic acid, etc. It also includes rubber binders or rubber added during polymerization to impart toughness.

Furthermore, other polymers may be blended with the above-mentioned Stephun-based polymer to the extent that its properties are not impaired.

The present invention will be explained below using Examples and Comparative Examples. First, Table 1 shows the styrene polymers used.

*Examples 1 to 4/Comparative Examples 1 to 3 First, as Example 1, Polymer A was used, and an extrusion foaming machine consisting of a screw extruder, a blowing agent injection mixer, a cooler, and a die for the bottom shape of a plate-like object was prepared. Foaming was performed using a device.

100 parts by weight of polymer, 2,2-bis(4
A raw material consisting of 2 parts by weight of -allyloxy-3,5-dipromonoenyl) propane and 0.03 parts by weight of an indigo compound named Vat Blue 1 in the color index as a nucleating agent was continuously fed into a part of the extruder screw hopper. supply,
Using a blowing agent injection mixer, 10 parts by weight of a mixed blowing agent consisting of dichlorodifluoromethane and methyl chloride (1:1) was injected under pressure.

The resulting mixture was then mixed and cooled under pressure in a cooler, and the resin temperature was finally adjusted to 123°C.

The foaming agent-containing resin was foamed using a die under atmospheric pressure to obtain an extruded foam base plate having an average thickness of 56 mm, an average cross section of 160 mm, and an average cell diameter of about 0.7.

A test piece with a length of 50 mm was cut from this original plate, and the top and bottom sides in the thickness direction were planed equally for about 3 inches, and both ends in the width direction were cut off by about 30 inches each, resulting in a thickness of 50 mm and a width of 100 m.
The test piece having a length of 501 rLML was further divided into 5 equal parts in the thickness direction to obtain flat test pieces 1 to 5 numbered from the top surface.

The weight and volume of this flat test piece were measured, and the apparent density was determined.

The results are shown in the table below.

As seen on the wooden surface, the density distribution of the extruded foam original plate is low in the center and high towards the top and bottom ends.

Therefore, the portion higher than the minimum density becomes an excess density.

Here, as an indicator of excess density, we use the integrated value of the density difference higher than the lowest density in the center, that is, (37,1-36,0)+
(36,3-36,0)+(36,4-36,0)+(
37,3-36,0) = 3.1 is used.

Next, a test piece with a thickness of 501n11L1 width of 100mm and length of 100mm was taken out from the foam base plate in the same manner as in the density measurement above, and its 5% strain compressive strength was measured.It was 3.4
kg/crA.

In addition, the foam base plate was divided into two equal parts in the middle in the thickness direction, and the thickness was 25 mm.
A test piece of 50 mm in length and width was prepared, and a stress of 1.25 kg/cr; i was repeatedly applied to the entire surface in the thickness direction for 10 minutes.
A repeated compressive strain test was conducted over 10,000 times.

After 100,000 cycles, the thickness of the test piece decreased in the order of 20, and the amount of strain was 5.

Furthermore, two samples cut out from the original plate with a thickness of 25 m and 11 L, a width of 100 mm, and a length of 200 mm were arranged in parallel to form a 200 mm angle, and the thermal conductivity was measured in accordance with JIS A 1412 and found to be 0.027 Kcal/m/ It was Hr/'C.

For asphalt heat resistance, thickness 25rILrIL,
The test was conducted using a test piece with a width of 50 mm and a length of 100 mm.

First, a dividing line was placed at a position of 50 mm in the length direction of the test piece, and the upper end was fixed with a chuck so that the length direction was in a vertical relationship.

Next, a wall dimension depth of 200 mm made of an iron plate with a wall thickness of 3.2 mm,
JASA in a rectangular container with an opening of 300 x 300 mm.
6011 Class 3 waterproofing asphalt was added, placed on a fire tray containing dry river sand arranged to a thickness of about 110 mm, and heated from below with a gas stove (for propane gas).

The temperature of the asphalt was adjusted to a range of 200±5° C. as measured at a depth of about 50 mm from the surface of the asphalt after stirring thoroughly for 10 seconds.

A sample piece prepared by fixing it on a chuck was immersed in this asphalt solution for 5 seconds to the position of the above dividing line, and after taking it out, it was naturally cooled for 24 hours in a room controlled at about 20°C to harden the attached asphalt. I let it happen.

After cooling, we measured the thickness direction of the sample piece at a position 25 minutes from the above dividing line and the length dimension of the same sample piece in the direction of immersion in asphalt from the dividing line, and calculated the product of both, and found that it was 1020c77f. there were.

When the unreacted styrene monomer and styrene trimer contained in the finally obtained foam resin were analyzed in the same manner as described above, they were found to be 0.20% by weight and 0.87% by weight, respectively.

As judged from this analytical value, the styrene monomer and styrene trimer contained in the polymer used for foaming and the polymer forming the foam after foaming are almost unchanged.

considered to be approximately equivalent.

The main points of the above results are summarized in Table 2.

Next, as Comparative Example 1, extrusion foaming was performed under exactly the same conditions as in Example 1 except that Polymer B in Table 1 was used, and the obtained foam was evaluated and analyzed in the same manner.

The results are summarized in Table-2. Furthermore, in order to clarify the quantitative effect of styrene trimer contained in the polymer used for foaming, Polymer A containing 0.87% by weight of styrene trimer and Polymer B containing 0.13% by weight were 3/1. (Example 2), 1/1 (Example 3), and 1/3 (Comparative Example 2), extrusion foaming was performed as before, and the obtained foam was evaluated and analyzed. .

In addition, in order to investigate the upper limit of the styrene trimer content, when producing Polymer A, a styrene trimer was metered into the molten polymer coming out of the volatile matter separation and removal device using a separately prepared styrene trimer pump. Polymer C (Example 4) and Polymer F (Comparative Example 3) thus prepared were also subjected to extrusion foaming, evaluation, and analysis in the same manner as described above.

These results are shown in Table-2. Examples 5-6/Comparative Example 4
~5 Regarding the polymers used, Polymer D (Example 5), Polymer E (Example 6), and Polymer G were obtained by adjusting the vacuum pressure of the volatile matter separation and removal device when producing Polymer A.
(Comparative Example 4) and Polymer H (Comparative Example 5), extrusion foaming was carried out in the same manner as in Example 1 above, and the obtained foams were evaluated and analyzed.

The results are shown in Table-2. In Table 2, each evaluation item for the foam product is indicated by ◯, △, or × mark.

○ indicates the top % between the best and worst values for each evaluation item
For example, for 5% compressive strength, the best value in Table 2 is 3.5, and the worst value is 2.2kg/%. Since it is cnl,
3.2-3.5 kg/ca It'ritsu mark, 2.7
~3.1 kg/crrf is marked △, 2.2~2.6 k
g/crA is marked with an x.

Also, as a comprehensive evaluation, all items marked with ○ are excellent.
, items with ○ marks and some △ marks are ``Good Pass'', and at least one ×
Those with marks were shown as inferior.

As is clear from these results, when the amount of unreacted styrene monomer contained in the polymer used is 0.3% by weight or less, the 5% compressive strength is improved; It can be seen that when the amount of carbon fiber is 0.5% by weight or more, not only the 5% compressive strength is further improved, but also the excess density index, repeated compressive strain characteristics, and heat insulation performance are mutually improved.

Examples 7 to IO/Comparative Examples 6 to 11 These Examples/Comparative Examples relate to the nucleating agent found in the present invention that is particularly effective for flame-retardant styrenic polymer foams.

Copper phthalocyanine pigment blue 15:1 (Example 7) and anthraquinone solvent flue 35 (Example s) were used instead of indigo (color index naming, Bat Blue 1) used as a nucleating agent in Example 1. ,
Pigment Blue 66 (Comparative Example 6), Pigment Blue 29 (Comparative Example 7), and Bat Blue 4 (Comparative Examples). Comparative example 8),
Full Vent Red 135 (Comparative Example 9), Teisha
Extrusion foaming was carried out in the same manner as in Example 1, except that Suelo-3 (Comparative Example 10) and Solvent Green 3 (Comparative Example 11) were used.

The resulting foam was evaluated for average density, average cell diameter, cell control ability, and coloring power.

The bubble control ability here refers to the ability to refine the bubbles when foaming is performed by adding a certain amount (0.03 parts by weight) of a nucleating agent, and the average cell diameter of the resulting foam is 2. Those below 0 nm were marked with a circle (acceptable), and those exceeding 2.0 nm were marked with an x (impossible).

The coloring power is the ability of the nucleating agent to color the foam, and the nucleating agent is 0.
．． Disperse 03 parts by weight in 100 parts by weight of a colorless solvent, compare the hue of this solution and the resulting foam on white paper,
Items that appear to be approximately the same are marked with a circle (excellent), and items that are different are marked with an x (poor).

Next, in order to examine the reusability of the obtained foam resin, the foam was crushed and pelletized again using an extruder, and the pellets were used in an extrusion foaming device with a screw diameter of 30 mrn in the same manner as described above. Extrusion foaming was carried out again, and the same operation was repeated once again, giving a total of three extrusion foaming histories.

The resulting foam was evaluated for average density, average cell diameter, cell control ability, and reuse stability in the same manner as before.

Reuse stability refers to the foam control ability and the lasting stability of coloring power when reused, and it refers to the foam obtained from the first extrusion foaming and the foam obtained after three extrusion foaming cycles. Compare the results, and mark ○ (acceptable) for those that maintain bubble control ability and coloring power, and mark × (unacceptable) for those that have lost bubble control ability, coloring power, or both. ).

The above results are summarized in Table 3.

Furthermore, as a comprehensive evaluation in Table 3, those marked with a circle in any of the items of bubble control ability, coloring power, and reuse stability were rated as "excellent," and those with an x mark in any of the items were rated as "poor."

From Table 3, the nucleating agents belonging to the present invention (Examples 7 to 10) are excellent in bubble control ability, coloring power, and reuse stability, but the nucleating agents other than the present invention (Comparative Examples 6 to 11) Either they do not have the ability to control bubbles, or even if they do, the coloring power is poor, or they have the ability to control bubbles and coloring power but lack reuse stability.

Claims (1)

[Claims] 1. Flame retardance is imparted and the cell diameter is controlled by containing a flame retardant and an appropriate amount of a nucleating agent consisting of at least one of an indigo compound, a copper phthalocyan pigment, and an anthraquinone pigment. When producing extruded foam of styrenic polymer, 0.3% by weight or less of styrene monomer and 0.
．． 1. An improved method for making an extruded styrenic foam, characterized in that a styrenic polymer containing 5 to 15% by weight of styrene trimer is used. 2 Nucleating Agent Color Index (American Association Off Textile Chemistry and Colorists)
f Textile Chemists and Co.
Pat Blue 1 (indigo compound), Pigment Blue 15:1, 15:2.
15:3.15:4 (i-phthalocyan pigment), norbentofluor 35.83.105 (anthraquinone compound)
A method for producing a foam according to claim 1, wherein the foam is used in an amount of 0.02 to 0.5% by weight based on the polymer. 3. The method for producing a foam according to claim 1, wherein the flame retardant is a compound containing nitrogen having a decomposition temperature of 250° C. or lower.