DK154776B - PROCEDURE FOR THE PREPARATION OF AN EXTENSIVE FOAM BODY OF A THERMOPLASTIC, SYNTHETIC, ALKENYLAROMATIC POLYMER - Google Patents

Description

The invention relates to a process for producing a long foamed body of a thermoplastic, synthetic, alkenyl aromatic polymer according to the preamble of the claim.

in

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5 One of the main uses for styrene polymer foams is the thermal insulation area. A styrene polymer foam for thermal insulation preferably has small cells and excellent dimensional stability.

It is also highly desirable that the insulating value of the foam be maintained for as long as possible. From a manufacturing standpoint, certain halogen-containing compounds such as dichlorodifluoromethane have been well suited for the preparation of extruded styrene polymer foams. Currently, it is believed that such compounds, when released into the atmosphere, can reduce the efficiency of the ozone layer 15 as a sun shield, and it is therefore desirable that fluorinated and / or chlorinated compounds which can reduce the ozone layer's effectiveness can generally be eliminated from applications where they are eventually released into the atmosphere.

From U.S. Patent No. 3,287,477 and French Patent No. 1,215,410, polystyrene foams are known which, e.g. may contain 1-chloro-1,1,2,2,2-pentafluoroethane, optionally in admixture with other fluorinated and / or chlorinated compounds or hydrocarbons. Thus, US Patent No. 3,287,477 discloses an extrusion process and a suitable device which, in addition to foamable polymers, can also produce foamed thermoplastic polymers for which liquid or gaseous products can be used as foaming agents. French Patent No. 1,215,410 also relates to a process 30 for the production of foamable polymer masses based on thermoplastic, all-cooled alkenyl aromatic polymers, the foamable masses thus obtained and the foamed bodies having a density of 20 to 25 g / m first

The object of the invention is therefore to provide a process for producing an elongated foam body of a thermoplastic, synthetic, alkenyl aromatic polymer having a high dimensional stability and good thermal insulation ability with 2

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favorable aging resistance, thereby preventing the danger of the ozone layer in selecting the foaming agent mixture.

The invention relates to a method for producing a long foam body of a thermoplastic, synthetic, alkenyl aromatic polymer having a machine direction and a transverse direction, the body defining a large number of closed, unrelated gaseous cells, the cells having an average cell size from 0.1 to 1.2 mm, the foam body has a predominantly uniform cell structure and is free of discontinuities, the store is without significant variation in average cell size when measuring cell size by taking average cell diameter across the smallest cross-sectional dimension of the body ( is measured, for example, by ASTM method D 2842-69), has a cross-sectional area of at least 51.6 cm 2 and a minimum cross-sectional dimension of at least 6.35 mm, the foam body having a water vapor permeability which is not is greater than 2.27 g »cm / dm2 mbar and measured by ASTM Method C 355-64 Procedures for Desiccant Method, a density of 16 to 80 g / l, which method is characterized by using a foaming agent or a foaming mixture of a) 30 to 100% by weight of 1,1-difluoro-1-chloroethane and optionally at least one other compound of the formula: R 1 - CF 2 - R 2 wherein R 1 is a methyl, ethyl, chloromethyl, difluoromethyl, chlorofluoromethyl, fluoromethyl or trifluoromethyl group, and r 2 is hydrogen, chloro, fluoro or a trifluoromethyl or methyl group and the compound contains no more than 3 carbon atoms and if the compound contains only halogen 2 fluorine atoms, the compound must have 3 carbon atoms, and b) from 0 to 30% by weight of at least one compound selected from fluorochloromethane, methyl chloride, ethyl chloride, chlorodifluoromethane or 1,1-difluoroethane.

Volatile liquid foaming agents used to make foams in accordance with the method of

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3 according to the present invention may be mixtures of a high permeability foam agent and a low permeability foam agent. Either the high permeability foam agent and / or the low permeability foam agent may be a mixture of one or more suitable foaming agents. The low permeability foaming agent in the mixture of foaming agents which can be used to make foams in accordance with the present invention is conveniently from 30 to 70% by weight of foam sometimes at any one time.

10

Low permeability foams are: 1,1,1-trifluoropropane, 2.2-di fluoropropane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoro-2-chloroethane, 1.1, 1-trifluoro-2-chloroethane, pentafluoroethane, 1.1.2-trifluoroethane, 1,1,1-trifluoroethane, octafluoropropane and 1,1-difluoro-chloroethane and mixtures thereof. All the preceding compounds have the required permeability value and thermal conductivity.

Secondary or high permeability foams suitable for the preparation of foams in accordance with the present invention include: fluorochloromethane, methyl chloride, ethyl chloride, chlorodifluoromethane and 1,1-difluoroethane and mixtures thereof.

The term "alkenyl aromatic, thermoplastic, synthetic polymer" refers to a solid polymer from one or more polymerizable alkenyl aromatic compounds. The polymer or copolymer comprises in chemically bonded form at least 70% by weight of at least one alkenyl aromatic compound of the general formula

R

Ar-C = CH 2 wherein Ar represents an aromatic hydrocarbon group or an aromatic halohydrocarbon group of the benzene series and R is the hydrogen or methyl group. Examples of alkenyl aromatic resins are the solid homopolymers of styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ar-ethylstyrene.

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pure, arvinylxylene, archlorostyrene or arbromostyrene and the solid copolymers of two or more of such alkenyl aromatic compounds with minor amounts of other readily polymerizable olefinic compounds such as e.g. methyl methacrylate, acrylonitrile, maleic anhydride, citraconic anhydride, itaconic anhydride, acrylic acid and rubber reinforced (either natural or synthetic) styrene polymers.

The preparation of alkenyl aromatic thermoplastic polymer foams occurs in a known manner in which the volatile liquid foaming agent is injected into a heat-plasticized polymer stream in an extruder. From the extruder, the hot plasticized gel is passed to a mixer, the mixer being a rotary mixer in which a toothed rotor is housed in a housing whose inner wall has teeth which engage the teeth of the rotor. The hot plasticized gel from the extruder is fed to the input end of the mixer and removed from the output end as the current flows in a predominantly axial direction. From the mixer, the gel passes through coolers and from the coolers to a nozzle which extrudes a substantially rectangular plate.

In the preparation of foam bodies of the present invention, it is often desirable to add a nucleating agent such as e.g. talc, calcium silicate or indigo to reduce cell size.

A large number of foams were prepared by admixing polystyrene containing flame retardant, which is a commercial purity monochloropentabromocyclohexane, barium stearate, magnesium oxide and a nucleating agent. The mixture was born to an extruder, and a foam agent was continuously injected into the extruder's cylinder. Polystyrene foam was extruded as a rectangular plate having a cross-sectional dimension 35 of approx. 2.54 x 25.4 cm. The foaming temperatures were from 112 to 118 ° C. All concentrations indicated as parts or parts per hundred (pph), are parts by weight per hour. 100 parts polystyrene resin. The feed rates, the foam composition and the

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Five properties are listed in the following tables. Density is given in g / Ί, cell size in mm; below the foam part is shown the weight percent and component of the foam agent.

5 The foams manufactured and listed in the tables contained 3 parts per 100 of the flame retardant, 0.075 parts per

100 bar ium stearate, 0.03 parts per 100 magnesium oxide. The units of the measured K-factor are J / sec. And are determined on samples cut from the extruded fabric in such a way that all the surfaces of the rectangular sample have been cut off from the initially extruded beam to obtain cut cells from each of the surfaces. Aging of the samples occurred at room temperature of approx. 20-25 ° C. In the column "calculated K-factor", values calculated for the K-factor of foam 15 after 5 years at ambient temperature in air and the K-factor for absolute aging are found. Knowing the density, cell size, foam concentration, foam composition, K factor, foam permeability, K factor when the foam has just been extruded, the K factor can easily be calculated with great accuracy at any later time. The K-factor after absolute aging is the K-factor that the foam would have if the foam agent in the cells had been completely replaced by air. The extrusions shown in experiments 7 and 8 of the table do not provide a foam in accordance with the present invention, but serve for comparison purposes only. If the cell size and the K factor are assessed, it is obvious that for any of the foaming systems, the smallest cell size gives the lowest K factor. It should also be noted that from the first six lines of the table, the long-term insulation value is significantly improved by the use of a low permeability foaming agent in conjunction with a high permeability foaming agent. The permeability of the density is cm3 / 0.025 mm / 645 cm2 / day / atm. Methyl chloride permeability = 980, 1,1-difluoro-ethane permeability = 8.4, chlorodifluoromethane permeability 35 s 19, ethyl chloride permeability = 84, air permeability * 110, chlorofluoromethane permeability = 329, and 1,1-difluoro-1 * chloroethane permeability 0.07.

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DK 1 SATIS B

Table 2 shows the dimensional stability of various foams from Table 1.

Table 2 5

The effect of foam type on the dimensional stability of the foam

Dimensional stability at 60 ° C and a relative humidity of 100% (% change in 1 week)

Ex. Foam_ Vertical Horizontal Ext.

2 50/50 chlorofluoromethane / -0.23 -0.05 +0.24 1.1-di fluoro-1-chloroethane 50/50 methyl chloride / -0.17 +0.19 +0.32 1.1-difluoro-1 -chloroethane 8 8 chlorofluoromethane -0.41 -0.18 -0.10 (comparative example) 9 40/60 chlorofluoromethane / -1.37 +0.35 +0.22 1.1- difluoro-1-chloroethane 10 30/70 chlorofluoromethane / -0.95 -0.23 +2.33 1.1- Difluoro-1-chloroethane 20/60 60/40 Chlorofluoromethane / -0.80 -0.12 +0.48 1.1- Difluoro-1-chloroethane 12 70 / Chlorofluoromethane / -1.40 -0.32 +0.13 1.1-difluoro-1-chloroethane 13 40/60 methyl chloride / -0.43 +0.14 +0.33 1.1-difluoro-1-chloroethane 40 / 60 1,1-difluoroethane / -0.67 +0.57 +1.00 1.1-difluoro-1-chloroethane 16 1,1-difluoro-1-chloroethane -0.45 -0.41 +5.07 30 17 40/50/10 chlorophenyl--0.21 +0.05 +0.88 than / 1,1-difluoro-1-chloroethane / chlorodifluoromethane 18 39 / 48.7 / 12.3 chloro--0.21 + 0.02 + 0.32 fluoromethane / 1,1-difluoro-1-chloroethane / 1,1-di fluoroethane

Claims (1)

DK 154776 B Table 2 (continued) Effect of foam type on dimensional stability of the foam Dimensional stability at 60 ° C 5 and a relative humidity of 100% (% change in 1 week) Ex. Foam Agent Vertical Horizontal Ext, 19 40/40/20 Chlorofluoro--0.44 +0.05 +0.20 Methane / 1,1-Difluoro-1-Chloroethane / Chloro-difluoromethane 40/40/20 Chlorofluoro -0.19 +0.03 +0.34 methane / 1,1-difluoro-1-chloroethane / 1,1-difluoroethane 40 40/50/10 methyl chloride / -0.62 -0.04 +0, 39 1.1-difluoro-1-chloro-ethane / chlorodifluoromethane 22 40/40/20 methyl chloride / -1.08 + 0.15.0 1.1-difluoro-1-chloro male / chlorodifluoromethane 7n 23 50/50 ethyl chloride / -0 , 77 -0.10 +0.63 1.1- Difluoro-1-chloro-ethane Foam bodies made according to the present invention have a K value after 5 years of aging at ambient temperature in air of at least 4,187 · 10 ”5 J / sec · Cm · ° C lower than the 25 K value for the foam in which the foam has been replaced by air. Claims. A method of producing an elongated foam body of a thermoplastic, synthetic, alkenyl aromatic polymer having a machine direction and a transverse direction, the body defining a large number of closed, unrelated gaseous cells, the cells having an average cell size of 0.1 to 1.2 mm, the foam body has a predominantly uniform cell structure and is free of discontinuities, the body is unimportant, when the cell size is measured by taking the average of the cell diameter across the smallest cross-sectional dimension of the body, has a cross-sectional area of at least 51.6 cm2 and has a minimum cross-sectional dimension of at least 6.35 mm, has a water vapor permeability of not more than 2.27 g «cm / dm2 mbar and a density of 16 to 80 g / l, characterized using a foaming agent or foaming composition of 10 a) 30 to 100% by weight of 1,1-difluoro-1-chloroethane and optionally at least one other compound of the formula: R 1 - CF 2 - R2 wherein R1 is a methyl, ethyl, chloromethyl, fluoromethyl, difluoromethyl, chlorofluoromethyl or trifluoromethyl group and R2 is hydrogen, chloro, fluoro, a trifluoromethyl or methyl group and the compound contains at most 3 carbonates and if the compound as halogen contains only 2 fluorine atoms, then the compound must have 3 carbon atoms, and b) from 0 to 30% by weight of at least one compound selected from fluorochloromethane, methyl chloride, ethyl chloride, chlorodifluoromethane or 1.1 difluoroethane. 25 30 35