JP3270109B2 - Styrene-based resin foam and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible, self-extinguishing and ultra-highly foamed styrene-based resin foam particle molding and a method for producing the same, which are mainly used for heat insulating materials. Self-extinguishing, heat-insulating styrene-based resin foam that can be fitted between pillars, joists, support frames, etc. of buildings in a thermal insulation method, and can be fitted without gaps between members. About.

[0002]

2. Description of the Related Art Conventionally, highly foamed styrene resin foams have been widely used as heat insulating materials because of their high closed cell ratio, low water absorption, and excellent heat insulating properties. For these applications, a high expansion ratio is desirable, and various methods for obtaining a heat insulating material having a high expansion ratio have been proposed. For example, Japanese Utility Model Publication No. 58-25064 discloses a density of 0.005 to 0.03.
Of 5 g / cm ^3, the density of 0.005~0.100g / cm ³ in JP-B-60-17909, Japanese Utility Model 61-
No. 46096 discloses a density of 0.010 to 0.100 g /
A molded article of a synthetic resin foam containing a styrene-based foam of cm ³ is disclosed.

[0003] However, the above-mentioned technology does not disclose a highly foamed molded article having a flame retardant or self-extinguishing property by blending a flame retardant. Self-extinguishing properties are required for heat insulating materials for houses, particularly for wooden houses. Generally, when a styrene resin is mixed with a flame retardant, the density becomes 0.02 g / cm.
Only about ³ foams can be obtained. Even though self-extinguishing properties can be obtained, flexibility cannot be obtained at this level of expansion ratio. In order to obtain flexibility, it is necessary to further expand the foam.However, when the foaming rate is increased, the cell membrane of the foam becomes thinner. And water absorption increases. Furthermore, if the cell membrane is easily torn, the expanded particles of the expanded bead have a low expansion force at the time of molding, so that the space between the expanded particles cannot be sufficiently filled, and a gap remains between the expanded particles. The rate increases. If the water absorption is high as described above, there is a problem that the heat insulating performance is reduced and the requirements as a heat insulating material are not satisfied.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to an ultra-highly foamed heat insulating material which does not decrease the closed cell ratio even if it contains a large amount of a flame retardant, has a small amount of interstices between particles, and has excellent flexibility. And a method for producing the same.

[0005]

According to the present invention, there is provided a foam obtained by molding styrene-based resin expandable particles in a mold, and (1) 100 parts by weight of a styrene-based resin, and a flame retardant. 0 to 15 parts by weight, and (2) a density of 0.006
０．０１0.014 g / cm ³ , and (3) the closed cell characteristic is 0.5 g / cm ³ or less.
In particular, when the styrenic resin and the flame retardant
It is characterized by holding at 30 ° C. or more for at least 15 minutes.

The styrenic resin in the present invention includes:
Other than polystyrene, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, styrene-butadiene copolymer and other copolymers containing styrene as a main monomer, and hydrogenated styrene-butadiene copolymer or mixtures thereof are used. it can. Further, a mixture with another thermoplastic resin can be used to such an extent that foaming is not hindered.

The volatile organic blowing agents in the present invention include propane, butane, pentane, hexane, 1-chloro-1,1-difluoroethane, monochlorodifluoromethane, monochloro-1,2,2,2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,2-
Tetrafluoroethane and the like can be used. These volatile organic blowing agents can be used alone or in combination.

The amount of the styrene resin is 0.07 to 0.25 g mol, preferably 0.1 to 100 parts by weight, based on 100 parts by weight of the styrene resin.
０．２0.2 g mol. Examples of the flame retardant in the present invention include hexabromocyclododecane, tetrabromobisphenol, pentabromomonochlorocyclohexane, tetrabromobutane, pentabromoethylbenzene, tribromophenol, trisphosphate, hexabromobenzene, decabromodiphenyl ether and the like. Among them, hexabromocyclododecane, tetrabromobisphenol and pentabromomonochlorocyclohexane are particularly preferred. These flame retardants may be used alone or as a mixture, or may be a mixture with other flame retardants other than those described above. The amount used is 1.0 to 15 parts by weight, preferably 1.0 to 10 parts by weight, based on 100 parts by weight of the styrene resin.

The foam of the present invention has a closed cell characteristic of 0.5 g / c.
m ³ or less, preferably 0.4 g / cm ³ or less, and the closed cell characteristics were measured by the following method. In short, the closed cell characteristics are indexes for evaluating the foaming performance of the foam and the degree of tearing of the cell membrane. That is, the sample is composed of a cut surface having a size of 15 mm x 15 mm x 100 mm and not having a co-molded surface of the sample in water in a container having a sufficient water capacity to seal the sample in water and a function capable of sealing. A foam sample (volume V, weight W ₀ ) cut out so as to be cut 10 m below the water surface
m and submerged, and seal the container. Next, the pressure in the container is reduced to 460 mmHg, and the container is left for 10 minutes. Thereafter, the internal pressure of the container was returned to the atmospheric pressure, and the sample was taken out. The sample was gently immersed in pure methanol for about 2 seconds to remove water adhering to the surface, and then dried in a dryer at 60 ° C. for 5 minutes to weigh W Measure ₁ and determine by the following formula. Closed cell characteristics = (W ₁ −W ₀ ) / V (g / cm
³ ) In order to obtain the foam of the present invention, for example, a styrene-based resin and a flame retardant are supplied into an extruder and melted under pressure in the extruder.
Separately, the volatile organic foaming agent was injected through a foaming agent supply line connected to the extruder, mixed well with the resin in a molten state, and then extruded into a thread form from a nozzle provided in a die of the extruder, and water was immediately stored. There is a method in which foaming resin particles are obtained by cutting in a length direction with a rotary cutter while being sandwiched between two upper and lower drive rolls while cooling in a cooling bath. In some cases, the flame retardant and the volatile organic blowing agent may be simultaneously supplied to the extruder.

Next, these foamable resin particles are highly foamed by steam using a known molding machine for polystyrene foam beads. In the above method, after the styrene resin and the flame retardant are contact-mixed in the extruder, and maintained at a high temperature and a high pressure of 130 ° C. or more for at least 15 minutes until extruded, the target density is 0.006. ~ 0.014
A foam having good self-extinguishing properties with closed cell characteristics of g / cm ³ can be obtained.

[0011] To extend the time for maintaining the temperature under a high temperature and a high pressure of 130 ° C or more, a conduit may be provided between the extruder and the die, and the length of the conduit may be adjusted. Alternatively, it is possible to adjust the time for maintaining the temperature under high temperature and high pressure by adjusting the extrusion amount. The present invention is achieved by increasing the time during which the styrene-based resin and the flame retardant are maintained in a state of high temperature and high pressure in an extruder. The reason is not always clear, and the present inventors initially considered this phenomenon to be kneadability and repeated experiments, but after mixing the effect more than kneadability, the aging time until cooling was reduced. Thus, it is presumed that the resin and the flame retardant come into contact with each other under a high temperature and a high pressure for a long time to improve the affinity and the uniformity of the two.

Conventionally, when a required amount of a flame retardant is added to a high foam, the cell membrane is broken at the time of foaming, and an ultrahigh foam having good closed cell properties cannot be obtained. Self-extinguishing heat-insulating foams can now be obtained easily.

[0013]

Examples 1 to 3 and Comparative Examples 1 and 2 The foam of the present invention was produced using the production apparatus shown in FIG. Polystyrene resin (Polystyrene # 683, MFR3.
0, softening point 105.5 ° C.) A mixture of 100 parts by weight of hexabromocyclododecane as a flame retardant and 0.3 parts by weight of talc as a nucleating agent was added to hopper 1
Into an extruder 2 (30φ, L / D = 20), melt-knead at 200 ° C. with a screw 3 and a mixer 4, and supply isopentane as a blowing agent from a supply port 5 to 100 parts by weight of the resin. The mixture was injected and kneaded at a ratio of .15 g mol.

The mixed composition was kept warm and led to a nozzle 7 via a conduit 6 containing a mixer. Length 50c
m, in the case of Example 1 using the conduit 6 having an inner diameter of 30 cm, the resin temperature at the inlet of the conduit 6 is 185 to 188 ° C.
And the resin temperature at the outlet of the conduit 6 was 130 ° C. Further, the holding time at 130 ° C. or more after the resin composition was charged from the hopper 1 to the nozzle was 15 minutes.

Further, in the second embodiment in which the length of the conduit 6 is 100 cm, the holding time at 130 ° C. or more is 22 minutes, and in the third embodiment in which the length of the conduit 6 is 150 cm, 130 ° C.
The above retention time was 29 minutes. The thread-like strand extruded from the nozzle 7 is quenched in a water tank 8 storing water at 22 ° C., and then taken up by a pair of rolls 9.
To obtain expandable particles having a diameter of 0.5 mm and a length of 2.5 mm.

The expandable particles were heated in a closed structure foaming machine at a steam pressure of 0.1 kg / cm ³ for 30 seconds to obtain primary expanded particles. Next, the primary expanded particles are put in a thickness of 25 m.
m, 30 cm in height and 30 cm in width, using a normal EPS molding machine (Piony 75, manufactured by Kasahara Kogyo Co., Ltd.) with a steam pressure of 0.2 kg / cm ² , a preheating condition of 10 seconds, and a steam pressure. Molding was performed under heating conditions of 0.7 kg / cm ² and 5 seconds to obtain a molded body. The density, closed cell properties and self-extinguishing properties of these foamed molded articles were measured, and the appearance was evaluated. The results are shown in Table 1.

Separately, foams were obtained in the same manner as in Examples 1 to 3 except that no conduit was used as a comparative example. The physical properties of these foams were evaluated in the same manner as in the examples, and the results are shown in Table 1. . In this case, the time maintained at 130 ° C. or higher after the supply of the flame retardant was 5 minutes in Comparative Example 1 and 8 minutes in Comparative Example 2. The self-extinguishing properties and appearance were determined by the following methods.

Self-extinguishing property: Five test pieces having a thickness of 10 mm, a length of 200 mm and a width of 25 mm are cut out from the molded product. A line perpendicular to the length direction is provided at a position 10 mm from the longitudinal end of the surface as an ignition limit instruction line, and a combustion limit instruction line is placed at a position 160 mm away from the ignition limit instruction line in parallel with the ignition limit instruction line. Provide.

As a fire source, a candle having a thickness of about 20 mm is used.
The length of the flame shall be 50 mm or more. The specimen is held horizontally, the candle is moved horizontally, and the candle is advanced to the ignition limit indicator line for about 5 seconds. When the ignition limit indicator line was reached, the flame was retracted, and the state in which the ignited flame spontaneously extinguished was observed. ○ …… The flame goes out by the combustion limit indicator line. (All 5 samples) × ... Even one sample out of 5 samples whose flame did not extinguish by the combustion limit indicator line.

Appearance:…: small gap between particles and perfect fusion state between particles ×: large gap between particles and incomplete fusion state between particles

[0021]

[Table 1]

[0022]

Examples 4 to 8 and Comparative Example 3 A foam was produced in the same manner as in Example 2 except that the amount of the flame retardant and the amount of the foaming agent were changed as shown in Table 1, and the physical properties were measured. The results are also shown in Table 1. Separately, as Comparative Example 3, a foam was obtained in the same manner as in Example 2 except that no flame retardant was added, and the physical properties are also shown in Table 1.

From the above results, according to the production method of the present invention, the density of each of the obtained foams is 0.014 g / cm ^2.
Or less, and the closed-cell characteristics are also 0.5 g / cm ³ or less,
It was confirmed that a foam having self-extinguishing properties and good appearance was obtained. On the other hand, in the comparative example, there was a gap between the particles of the foam, the fusion state was incomplete, and only a foam having a large closed cell characteristic was obtained.

If no flame retardant is added, the density is 0.0
Although it is possible to obtain a molded article having an extremely high foaming of 11 g / cm ³ , it is understood that a foam having high foaming properties and excellent closed-cell properties while blending a flame retardant cannot be obtained unless according to the present invention. .

[0025]

According to the present invention, the self-extinguishing property of the heat insulating material for wooden houses can be improved. Furthermore, since a flexible heat insulating material with a high expansion ratio can be obtained, a self-extinguishing heat insulating material that can be inserted without gaps in a wooden frame construction method can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an extrusion apparatus useful for the production method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hopper 2 Extruder 3 Screw 4 Mixer 5 Supply port 6 Conduit 7 Nozzle 8 Water tank 9 Roll 10 Cutter

Claims (2)

(57) [Claims] 1. A foam obtained by molding styrene-based resin expandable particles in a mold, comprising (1) 1.0 to 15 parts by weight of a flame retardant per 100 parts by weight of a styrene-based resin,
(2) density of 0.006~0.014g / cm ^{3, (3)} a styrene resin foam independent bubbles characteristic is equal to or is 0.5 g / cm ³ or less. 2. A resin melt comprising a styrene-based resin containing a flame retardant and a volatile organic foaming agent is extruded from an extruder, cut to obtain foamable particles, and the foamable particles are primarily foamed.
Then, in the method of producing a styrene foam to be molded in a mold,
Flame retardant 1.0 to 100 parts by weight of styrene resin
15 parts by weight and 0.07 to 0.25 g of a volatile organic blowing agent
The styrene-based resin and the flame retardant are kept at 130 ° C. or more in the extruder for at least 15 minutes, and the density is 0.006 to 0.01.
4g / cm ^3, and the independent bubble characteristics 0.5g / cm ³
The following method for producing a styrene resin foam.