WO2002034821A1

WO2002034821A1 - Compositions for the production of poly(meth)acrylimide foams containing expanded graphite

Info

Publication number: WO2002034821A1
Application number: PCT/EP2001/011377
Authority: WO
Inventors: Sabine Servaty; Peter Stein; Thomas Barthel; Werner Geyer
Original assignee: Röhm GmbH & Co. KG
Priority date: 2000-10-21
Filing date: 2001-10-02
Publication date: 2002-05-02
Also published as: AU2002213988A1; DE10052239A1

Abstract

The invention relates to compositions for the production of poly(meth)acrylimide foams with reduced flammability, containing expanded graphite. The invention further relates to poly(meth)acrylimide moulding masses, poly(meth)acrylimide foams, obtained from the above compositions and moulding masses and methods for the production of poly(meth)acrylimide foams with reduced flammability.

Description

COMPOSITIONS FOR PRODUCING BLUE GRAPHITE CONTAINERS

Poly (meth) acrylimide foams

The present invention relates to compositions for the production of poly (eth) acrylimide show materials • with reduced flammability, poly (meth) acrylimide molding compositions, poly (meth) acrylimide foams and processes for their production.

Poly (meth) acrylimide foams have been known for a long time and are widely used because of their excellent mechanical properties and their low weight, in particular in the production of layered materials, laminates, composites or foam composites. Here ^■ prepregs with core materials made of poly (meth) acryli id are often linked.

For example, they are used in aircraft construction, shipbuilding and also in buildings. For many of these numerous applications, they have to meet fire protection requirements, which are laid down in legal regulations and a number of other regulations.

Evidence that the foams meet the fire protection requirements is carried out with the aid of a large number of different fire tests, which are usually aimed at the use of the foam or the composite body containing the same. In general, the poly (meth) acrylimide foams are equipped with so-called Flame retardants are necessary for these tests to be passed.

The use of chlorine or bromine-containing compounds as flame retardants is widely known. These compounds are often used together with antimony oxides. The disadvantage here, however, is that poly (meth) acrylimides, the flammability of which is reduced as a result, are extremely difficult to recycle, since these halogenated hydrocarbons can hardly be separated from the polymer and dioxins can be formed from these compounds in waste incineration plants.

In addition, toxic gases such as HCl and HBr are formed in the event of a fire. Because of these disadvantages, the general aim is to avoid chlorinated and brominated substances as additives in plastics as far as possible.

Phosphorus compounds are another class of flame retardants with which poly (meth) acrylimide foams are finished. The disadvantage here is in particular that a very high fire

Flue gas density arises, which also occurs with halogen-containing flame retardants. Due to their toxicity, these flue gases endanger people who inhale these gases, on the one hand, and make rescue work more difficult.

Furthermore, many of the phosphorus compounds used as flame retardants act as plasticizers. This undesirable effect limits the amount of phosphorus compounds added.

In addition, the previously known flame-retardant poly (meth) acrylimide foams do not all exist for certain applications Fire safety standards. For example, known foams, which are obtained according to DE-OS 33 46 060, EP-A-0 146 892 or US 4 576 971, are self-extinguishing, but do not or only insufficiently meet the vertical flame test according to 60s

FAR 25.853 (a) (1) (i) or the flue gas density test according to FAR 25.853 (c), AITM 2.0007 and show high heat development according to FAR 25.853 (c). A strong dependency on the density of the test specimen is particularly noteworthy. Foams with a high density may pass the vertical flame test 60s, but show very high heat development. The materials mentioned above do not pass the fire test for rail vehicles in accordance with DIN 54837.

In view of the prior art specified and discussed herein, it was therefore an object of the present invention to provide compositions for the production of poly (meth) acrylimide foams with reduced flammability, poly (meth) acrylimide molding compositions and poly (meth) acrylimide foams which show a low smoke development according to FAR 25.853 (c), AITM 2.0007 and a low heat development according to FAR 25.853 (c). Furthermore, the foams should pass the vertical flame test 60s according to FAR 25.853 (a) (l) (i).

Another problem was to create poly (meth) acrylimide foams that meet the standards of the fire test for rail vehicles according to DIN 54837.

Another object of the invention was to provide poly (meth) acrylimide foams with low flammability, the reduced amounts of Have phosphorus compounds or halogenated hydrocarbons.

The invention was also based on the object of specifying the most cost-effective flame retardant for poly (meth) acrylimides and / or poly (meth) acrylimide foams.

I

In addition, it was therefore an object of the present invention that the flame retardant used to finish the poly (meth) acrylimides or the poly (meth) acrylimide foams should be as safe as possible from a health point of view.

These tasks as well as others which are not named literally, but which can be derived as a matter of course from the contexts discussed here, or which necessarily result from these, are solved by the measures described in claim 1. Appropriate modifications of the composition according to the invention are protected in the subclaims which refer back to claim 1.

The object with regard to the poly (meth) acrylimide molding composition is achieved by the measures described in claim 7.

With regard to the poly (meth) acrylimide foam, the subject matter of claim 9 provides a solution to the problem on which the invention is based.

A particularly advantageous embodiment of a method for producing a poly (meth) acrylimide foam according to the invention is described in Process claim 10 provided. A layer material is described in claim 14.

Due to the fact that compositions for the production of poly (meth) acrylimide foams or poly (meth) acrylimide molding compositions have expandable graphite, it is possible to provide poly (meth) acrylimide foams and poly (meth) acrylimide molding compositions with reduced flammability, which show a low smoke development and a low heat development.

The measures according to the invention include achieved the following advantages in particular:

--- The flame retardant poly (meth) acrylimide

Foams form only small amounts of toxic gases when burned, such as HCN, CO, NO _x , H ₂ S and S0 ₂ .

=> The use of expanded graphite ensures low flammability of poly (meth) acrylimides and / or poly (meth) acrylimide foams. The plastics obtained are generally self-extinguishing.

=> Compositions according to the invention can be produced inexpensively, since relatively expensive flame retardants are replaced by inexpensive expanded graphite.

=> Poly (meth) acrylimides and poly (meth) acrylimide foams according to the invention can be recycled inexpensively, since the proportion of halogenated compounds can be kept very low. - = From the poly (meth) acrylimides or. the

Poly (meth) acrylimide foams do not produce any or only very small amounts of toxic halogenated hydrocarbons when burned.

---> Poly (meth) acrylimide foams according to the invention show excellent mechanical properties despite reduced flammability.

- => The fire-protected according to the invention

Poly (meth) acrylimide foams pass the fire test for rail vehicles according to DIN 54837.

Expandable graphite used according to the invention to reduce the flammability of poly (meth) acrylimides and / or poly (meth) acrylimide foams is known per se. Expandable graphite expands when heated. ^" It is believed that this

Property is generated by special inclusions of atoms or molecules in the layer structure of the carbon compound. Expandable graphite can be obtained, for example, by reacting graphite with sulfuric acid. Methods of

Manufacture of expandable graphite is described, inter alia, in US-A-3,574,644. Usually the density of expandable graphite is in the range from 1.5 to 2.1 g / cm ³ , the average particle size is from 70 to 2000 μm, in particular from 100 to 100 μm, without any intention that this should impose a restriction.

Expandable graphite in the composition according to the invention is preferably in the range from 1 to 50% by weight. -%, particularly preferably 5 to 30 wt. -%, based on the total weight of the monomers, used, without this being intended to be a limitation. The upper limit results on the one hand from economic Considerations, on the other hand, the mechanical properties can be adversely affected. Amounts less than 1 wt. -% in many cases only lead to a slight reduction in flammability if no further flame retardants are added.

In addition to expandable graphite, the composition according to the invention can contain further flame retardants in order to additionally reduce the flammability. These flame retardants are widely known in the art. In addition to halogen-containing flame retardants, some of which contain antimony oxides, phosphorus-containing compounds can also be used. Compounds containing phosphorus are preferred due to the better recyclability of the plastics.

The phosphorus compounds include, among others, phosphines, phosphine oxides, phosphonium compounds, phosphonates, phosphites and / or phosphates. These compounds can be organic and / or inorganic in nature, derivatives of these compounds, such as phosphoric acid monoesters,

Phosphonic acid monoesters, phosphoric acid diesters, phosphonic acid diesters and phosphoric acid triesters as well as polyphosphates are included.

Phosphorus compounds of the formula (I) are preferred

X-CH ₂ -P (0) (OR) ₂ (I),

wherein R are identical or different radicals from the group methyl, ethyl and chloromethyl and X is a hydrogen or halogen atom, a hydroxyl group or a group R ^ -CO-, wherein R ^{1 is} methyl, ethyl or chloromethyl. Examples of phosphorus compounds according to formula (I) include dimethyl methane phosphonate (DMMP), diethyl ethane phosphonate, dimethyl chloro ethane phosphonate, diethyl chloromethane phosphonate, dimethyl hydroxymethane phosphonate, diethyl hydroxymethane phosphonate,

Methoxycarbonylmethanphosphonsäuredimethylester and Ethoxycarbonylmethanphosphonsäurediethylester.

The phosphorus compounds can be used individually or as a mixture. Mixtures which contain phosphorus compounds of the formula (I) are particularly preferred.

These compounds can be used in a proportion of up to 25% by weight, based on the weight of the monomers, in order to meet the fire protection standards. In preferred embodiments, the proportion of phosphorus compounds is in the range from 1 to 15% by weight, without any intention that this should impose a restriction. If increasing amounts of these compounds are used, the other thermal and mechanical properties of the plastics, such as, for example, the compressive strength, the bending strength and the heat resistance, may deteriorate.

By using expandable graphite to reduce the flammability of poly (meth) acrylimides or poly (meth) acrylimide foams, the amounts of phosphorus or halogen-containing flameproofing additives can be significantly minimized with a constant LOI value, so that the plastic has particularly good mechanical and has thermal properties.

Mixtures of at least one phosphorus compound and expandable graphite are of particular interest exhibit. It has surprisingly been found that such mixtures have a synergistic effect.

Phosphorus-containing flame retardants and expandable graphite are preferably used in a mass ratio in the range from 1:20 to 20: 1, preferably 1: 5 to 5: 1, based on the weight of the compounds, without any intention that this should impose a restriction.

The reduced flammability can be determined, for example, by the so-called LOI values (Low Oxygen Index). The higher the LOI value, the less flammable the tested material is. The LOI values can be determined, for example, in accordance with ASTM Standard D 2863: Standard Method of Test for Flammability of Plastics Using the Oxygen Index Method. The LOI value corresponds to an oxygen-nitrogen gas mixture in which a plastic sample ignited at the upper end, which is in the form of a molded body, just burns completely.

Reduction here means an increase in the LOI value by adding expandable graphite, based on the molded article produced from the poly (meth) acrylimide molding composition or the poly (meth) acrylimide foam without this additive. The LOI value of untreated poly (meth) acrylimide foams is approximately 20. In general, therefore, one can speak of a reduced flammability with LOI values greater than 22, preferably greater than 24 and very particularly preferably greater than 27, without this is to be a limitation.

The foams show a low smoke development according to FAR 25.853 (c), AITM 2.0007 and a low heat development according to FAR 25.853 (c). In special embodiments, the heat development is < 160 kW / m ² , preferably ≤ 140 kW / m ² and particularly preferably <120 kW / m ² . Furthermore, the foams pass the vertical flame test 60s according to FAR 25.853 (a) (1) (i).

In addition, the poly (meth) acrylimide foams meet the standards of the fire test for rail vehicles according to DIN 54837. Special embodiments of foams according to the invention achieve an S4 flammability classification according to DIN 54837. The destroyed length is accordingly <20 cm and the afterburning time <10s. The smoke development class SR-2 is achieved in the test according to DIN 54837 with special designs. This means that the integral smoke density is <50% * min. Particularly preferred foams achieve values below 25% * min. In addition, particularly preferred foams are characterized by a low drop formation during firing. In this way, particularly preferred configurations are classified into the class ST2 according to the test according to DIN 54837.

Compositions according to the invention for the production of poly (meth) acrylimide foams are polymerizable mixtures which contain at least one, usually usually two or more monomers, such as (meth) acrylic acid and (meth) acrylonitrile, blowing agents, at least one polymerization initiator and expandable graphite. These compositions are polymerized into precursors from which poly (meth) acrylimide foams are formed by heating.

The spelling in brackets is intended to indicate an optional feature. For example, (meth) acrylic means acrylic, methacrylic and mixtures of the two. The poly (meth) acrylimide foams obtainable from the compositions according to the invention have recurring units which can be represented by formula (II),

wherein

R ¹ and R ^{2 are the} same or different hydrogen or a methyl group and R ^{3 is} hydrogen or an alkyl or aryl radical having up to 20 carbon atoms.

Units of structure (II) preferably form more than 30% by weight, particularly preferably more than 50% by weight and very particularly preferably more than 80% by weight of the poly (meth) acrylimide foam.

The production of rigid poly (meth) acrylimide foams is known per se and is described, for example, in GB-PS 1 078 425, GB-PS 1 045 229, DE-PS 1 817 156 (= US-PS 3 627 711) or DE-PS 27 26 259 (= U.S. Patent 4,139,685).

For example, the units of structural formula (II) can be formed from neighboring units of (meth) acrylic acid and (meth) acrylonitrile by a cyclizing isomerization reaction when heated to 150 to 250 ° C (cf. DE-C 18 17 156, DE -C 27 26 259, EP-B 146 892). Usually, a precursor is first by polymerizing the monomers in the presence of a radical initiator at low temperatures, e.g. B. 30 to 60 ° C with Post-heating to 60 to 120 ° C generated, which is then foamed by heating to about 180 to 250 ° C by a blowing agent contained (see EP-B 356 714).

For this purpose, for example, a copolymer can first be formed which contains (meth) acrylic acid and

(Meth) acrylonitrile preferably in a molar ratio between 1: 4 and 4: 1.

In addition, these copolymers can contain further monomer units which result, for example, from esters of acrylic or methacrylic acid, in particular with lower alcohols having 1-4 carbon atoms, styrene, maleic acid or their anhydride, itaconic acid or their anhydride, vinylpyrrolidone, vinyl chloride or vinylidene chloride , The proportion of the comonomers which are difficult or difficult to cyclize should not exceed 30% by weight, preferably 20% by weight and particularly preferably 10% by weight, based on the weight of the monomers.

Small amounts of crosslinking agents, such as. B.

Allyl acrylate, allyl methacrylate, ethylene glycol diacrylate or dimethacrylate or polyvalent metal salts of acrylic or methacrylic acid, such as magnesium methacrylate, can advantageously be used. The proportions of these crosslinkers are frequently in the range from 0.005 to 5% by weight, based on the total amount of polymerizable monomers.

In addition, metal salt additives can be used, which often reduce smoke gas. These include the acrylates or methacrylates of

Alkali or alkaline earth metals or zinc, zircon or lead. Na, K, Zn and Ca (meth) acrylate are preferred. Amounts of 2 to 5 parts by weight of the Monomers result in a significant reduction in smoke density during fire testing in accordance with FAR 25.853a.

The polymerization initiators used are those which are customary per se for the polymerization of (meth) acrylates, for example azo compounds, such as azodiisobutyronitrile, and peroxides, such as dibenzoyl peroxide or dilauroyl peroxide, or else other peroxide compounds, such as, for example, t-butyl peroctanoate or perketals, as well as optionally redox initiators (see also redox initiators) see, for example, H. Rauch-Puntigam, Th. Völker, Acryl- und MethacrylVerbindennungen, Springer, Heidelberg, 1967 or Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 1, pages 286 ff, John Wiley & Sons, New York, 1978 ). The polymerization initiators are preferably used in amounts of 0.01 to 0.3% by weight, based on the total weight of the monomers used.

It can also be advantageous to combine polymerization initiators with different disintegration properties with regard to time and temperature. For example, it is well suited the simultaneous use of tert-butyl perpivalate, tert-butyl perbenzoate and tert-butyl per-2-ethylhexanoate or of tert-butyl perbenzoate, 2, 2-azobisiso-2, 4-dimethylvaleronitrile, 2, 2-azobisisobutyronitrile and di -tert. -butyl peroxide.

The polymerization is preferably carried out via variants of bulk polymerization, such as the so-called chamber method, without being limited to this.

The weight average molecular weight M _{w of} the polymers is preferably greater than 10 ⁶ g / mol, in particular greater than 3 ^χ 10 ⁶ g / mol, without this being intended to impose a restriction.

In a known manner, blowing agents are used to foam the copolymer during the conversion into an imide group-containing polymer, which form a gas phase at 150 to 250 ° C. by decomposition or evaporation. Blowing agents with an amide structure, such as urea, monomethyl or N, N '-dimethylurea, formamide or monomethylformamide, release ammonia or - A ine upon decomposition, which leads to the additional formation of

Imid groups can contribute. However, nitrogen-free blowing agents such as formic acid, water or monohydric aliphatic alcohols having 3 to 8 carbon atoms, such as 1-propanol, 2-propanol, n-butan-1-ol, n-butan-2-ol, isobutan-1, can also be used -ol, isobutan-2-ol, pentanols and / or hexanols can be used. The amount of blowing agent used depends on the desired foam density, the blowing agents being used in the reaction mixture usually in amounts of about 0.5 to 15% by weight, based on the total weight of the monomers used.

The preliminary products can also contain customary additives. These include, among others, antistatic agents, antioxidants, mold release agents, lubricants, dyes, flame retardants,

Flow improvers, fillers, light stabilizers and organic phosphorus compounds such as phosphites or phosphonates, pigments, release agents, weathering agents and plasticizers.

Conductive particles that prevent the foams from becoming electrostatically charged are another class of preferred additives. These include metal and soot particles, too can be present as fibers, with a size in the range of 10 nm and 10 mm, as described in EP 0 356 714 AI.

In addition, anti-settling agents are preferred additives because these substances effectively stabilize the compositions for the production of polyacrylimide foams. These include carbon blacks, for example KB EC-600 JD from Akzo Nobel, and Aerosile, for example Aerosil 200 from Degussa-Hüls AG.

A poly (meth) acrylimide foam according to the invention can be produced, for example, by mixing a mixture of

(A) 20-60% by weight (meth) acrylonitrile, 40-80% by weight (meth) acrylic acid and

0-20% by weight of further vinylically unsaturated monomers, the constituents of component (A) giving 100% by weight;

(B) 0.5-15% by weight, based on the weight of components (A), of a blowing agent;

(C) 1-50% by weight, based on the weight of components (A), expandable graphite;

(D) 0.01 to 0.3% by weight, based on the weight of components (A), of a polymerization initiator;

(E) 0-200% by weight, based on the weight of components (A), of conventional additives

polymerized to a plate and then foamed this polymer plate at temperatures of 150 to 250 ° C. Another aspect of the present invention are poly (meth) acrylimide molding compositions with reduced flammability, which contain expandable graphite. These thermoplastically processable molding compositions have

Poly (meth) acrylimides with high heat resistance, which can be obtained, for example, by reacting polymethyl methacrylate or its copolymers with primary amines. Representative of the large number of examples of this polymer-analogous imidation are: US 4,246,374, EP 216 505 A2, EP 860 821. High heat resistance can be achieved either by using arylamines (JP 05222119 A2) or by using special co-monomers reach (EP 561 230 A2, EP 577 002 AI). All of these reactions result in solid polymers which can be foamed to obtain a foam in a separate second step, with suitable techniques known to those skilled in the art for this purpose.

Poly (meth) acrylimide molding compositions according to the invention contain expandable graphite as an essential constituent. This component is preferably used in the amounts set out above.

In addition, these molding compositions can have the optional additives mentioned above. They can be expanded with expandable graphite before, during or after the polymerization or imidation using known methods.

As previously mentioned, these molding compositions can be foamed using known techniques. This can include the blowing agents mentioned above are used, which can be added to the molding compounds by compounding, for example.

Poly (meth) acrylimide foams according to the invention can be provided with cover layers, for example to increase the strength. In addition, layer materials are known which offer a certain level of flame protection simply by choosing the covering material. When using the foams according to the invention, the fire protection achieved by using these composite materials can be significantly improved.

Any known flat structure can be used as the cover layer, which is stable in the processing parameters required for producing the composite structure, such as pressure and temperature. These include, for example, films and / or sheets made of polypropylene, polyester, polyether, polyamide, polyurethane, polyvinyl chloride, polymethyl (meth) acrylate, by curing reactive resins, such as, for example, ^• epoxy resins (EP resins), methacrylate resins (MA resins), unsaturated polyester resins (UP resins), isocyanate resins and phenacrylate resins (PHA resins), bismaleimide resins and phenolic resins, plastics and / or metals obtained, such as aluminum, for example. Furthermore, mats or webs can preferably be used as the top layer, which comprise glass fibers, carbon fibers and / or aramid fibers, wherein webs which have a multilayer structure can also be used as the top layer.

These fibrous webs can be applied to the foams, among other things, as prepregs. These are fiber mats pre-impregnated with curable plastics, mostly glass fiber mats or Glass filament fabric that can be processed into molded parts or semi-finished products by hot pressing. These include GMT and SMC.

Furthermore, carbon fiber reinforced plastics are also known which are particularly suitable as cover layers.

The thickness of the cover layer is preferably in the range from 0.1 to 100 mm, preferably in the range from 0.5 to 10 mm.

An adhesive can also be used to improve adhesion. Depending on the material of the cover layer, this is not necessary.

The poly (meth) acrylimide foams according to the invention and in particular the layer materials containing these foams can be used, for example, in aircraft construction and for the construction of ships or rail vehicles.

Examples and comparative examples

example 1

400 g (4 parts by weight) of isopropanol and 200 g (2 parts by weight) of water were added as a blowing agent to a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight). Furthermore, 5 g (0.05 part by weight) of tert.-

Butyl perbenzoate, 8g (0.08 part by weight) 2, 2-azobisiso-2, 4-dimethylvaleronitrile, 5g (0.05 part by weight) 2, 2-azobisisobutyronitrile and 5g (0.05 part by weight) Di-tert-butyl peroxide added as initiators. In addition, 1000g (10.0 wt. Parts) of dimethyl methane phosphonate (DMMP) and 1500 g (15.0 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) Were added as flame retardants. Finally, the mixture contained 40 g (0.40 part by weight) of release agent (PAT 1037), 70 g (0.70 part by weight) of ZnO and 140 g (1.4 part by weight) of carbon black (KB 600 EC from Akzo Nobel ).

This mixture was polymerized for 92 hours at 40 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then

Final polymerization is subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming took place for 3 hours at 193 ° C.

The foam thus obtained had a density of 48 kg / m ³ .

This foam was then subjected to various fire tests. These included the vertical test 60s in accordance with FAR 25.853 (a) (1) (i) and the flue gas density test in accordance with FAR 25.853 (c), AITM 2.0007. In addition, the fire test for

Rail vehicles according to DIN 54837 as well as an analysis of the smoke gases for toxic components according to AITM 3.0005. The results obtained are shown in Table 1.

Example 2

400 g (4 parts by weight) of isopropanol and 100 g (1 part by weight) of water were added as a blowing agent to a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight). Furthermore, the mixture was 5g (0.05 parts by weight) of tert-butyl perbenzoate, 8g (0.08 parts by weight) of 2,2-azobisiso 2, 4-dimethylvaleronitrile, 5g (0.05 parts by weight) 2, 2-azobisisobutyronitrile and 5g (0.05 parts by weight) di-tert-butyl peroxide added as initiators. In addition, 1000 g (10.0 parts by weight) of dimethyl methanephosphonate (DMMP) and 1500 g (15.0 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) were added to the mixture as a flame retardant. Finally, the mixture contained 40g (0.40 part by weight) of release agent (PAT 1037), 70g (0.70 part by weight) ZnO and, 140g (1.4 part by weight) carbon black (KB 600 EC from Akzo Nobel).

This mixture was polymerized for 92 hours at 40 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming was carried out for 2 hours at 195 ° C.

The foam thus obtained had a density of 55 kg / m ³ .

This foam was subjected to a heat development study in accordance with FAR 25.853 (c).

The data obtained are shown in Table 1.

Example 3

400 g (4 parts by weight) of isopropanol and 100 g (1 part by weight) of water were added as a blowing agent to a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight). In addition, 5 g (0.05 part by weight) of tert-butyl perbenzoate, 8 g (0.08 part by weight) of 2,2-azobisiso-2, 4-dimethylvaleronitrile, 5 g (0.05 part by weight) were added to the mixture. parts) 2, 2-Azobisisobutyronitrile and 5g (0.05 parts by weight) of di-tert-butyl peroxide added as initiators. In addition, 1000 g (10.0 parts by weight) of dimethyl methanephosphonate (DMMP) and 1000 g (10.0 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) were added to the mixture as a flame retardant. Finally, the mixture contained 40g (0.40 part by weight) of release agent (PAT 1037), 70g (0.70 part by weight) ZnO and 130g (1.3 part by weight) of carbon black (KB 600 EC from Akzo Nobel ).

This mixture was polymerized only 21 hours at 38 ° C. and then for another 48 hours at 39 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming was carried out for 2 hours at 195 ° C.

The foam thus obtained had a density of 50 kg / m ³ .

This foam was subjected to the tests set out in Table 1. This table also contains the data obtained.

Example 4

To a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight) were used as

Blowing agent 400g (4 parts by weight) of isopropanol and 200g (2 parts by weight) of water are added. In addition, 5 g (0.05 part by weight) of tert-butyl perbenzoate, 8 g (0.08 part by weight) of 2,2-azobisiso-2, 4-dimethylvaleronitrile, 5 g (0.05 part by weight) were added to the mixture. parts)

2, 2-Azobisisobutyronitrile and 5g (0.05 parts by weight) of di-tert-butyl peroxide added as initiators. In addition, 1000 g (10.0 parts by weight) of dimethyl methane phosphonate (DMMP) and 2000 g (20.0 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassrαan GmbH & Co.) were added as a flame retardant. Finally, the mixture contained 40g (0.40 part by weight) of release agent (PAT 1037), 70g (0.70 part by weight) ZnO and 130g (1.3 part by weight) of carbon black (KB 600 EC from Akzo Nobel ).

This mixture was polymerized for 71 hours at 40 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming was carried out for 2 hours at 190 ° C.

The foam thus obtained had a density of 52 kg / m ³ .

Example 5

400 g (4 parts by weight) of isopropanol and 200 g (2 parts by weight) of water were added as a blowing agent to a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight). In addition, 5 g (0.05 part by weight) of tert-butyl perbenzoate, 8 g (0.08 part by weight) of 2,2-azobisiso-2, 4-dimethylvaleronitrile, 5 g (0.05 part by weight) were added to the mixture. Parts) 2, 2-azobisisobutyronitrile and 5 g (0.05 parts by weight) of di-tert-butyl peroxide added as initiators.

In addition, 1000g (10.0 parts by weight) of dimethyl methanephosphonate (DMMP) and 2000g (20.0 Parts by weight) expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) As a flame retardant. Finally, the mixture contained 40 g (0.40 part by weight) of release agent (PAT 1037), 70 g (0.70 part by weight) of ZnO and 140 g (1.4 part by weight) of carbon black (KB 600 EC from Akzo Nobel ).

This mixture was polymerized for 92 hours at 40 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming took place for 3 hours at 193 ° C.

The foam thus obtained had a density of 58 kg / m ³ .

Example 6

500 g (5 parts by weight) of isopropanol and 200 g (2 parts by weight) of formamide were added as blowing agents to a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight). In addition, 5 g (0.05 part by weight) of tert-butyl perbenzoate, 8 g (0.08 part by weight) of 2,2-azobisiso-2, 4-dimethylvaleronitrile, 5 g (0.05 part by weight) were added to the mixture. Parts) 2, 2-azobisisobutyronitrile and 5 g (0.05 parts by weight) of di-tert-butyl peroxide added as initiators. In addition, 1000 g (10.0 parts by weight) of dimethyl methane phosphonate (DMMP) and 2500 g (25.0 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) were added to the mixture as a flame retardant. Finally, the mixture contained 40 g (0.40 part by weight) of release agent (PAT 1037), 30 g (0.30 part by weight) of ZnO and 120 g (1.2 part by weight) of carbon black (KB 600 EC from Akzo Nobel ).

The foam thus obtained had a density of 95 kg / m ³ . This foam was subjected to the tests set out in Table 1. This table also contains the data obtained.

Example 7

500 g (5 parts by weight) of isopropanol and 200 g (2 parts by weight) of water were added as a blowing agent to a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight). In addition, 5 g (0.05 part by weight) of tert-butyl perbenzoate, 8 g (0.08 part by weight) of 2,2-azobisiso-2, 4-dimethylvaleronitrile, 5 g (0.05 part by weight) were added to the mixture. Parts) 2, 2-azobisisobutyronitrile and 5 g (0.05 parts by weight) of di-tert-butyl peroxide added as initiators.

In addition, 1000 g (10.0 parts by weight) of dimethyl methane phosphonate (DMMP) and 2500 g (25.0 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) were added to the mixture as a flame retardant. Finally, the mixture contained 40g (0.40 part by weight) of release agent (PAT 1037), 70g (0.70 part by weight) ZnO and 150g (1.5 part by weight) carbon black (KB 600 EC from Akzo Nobel ). This mixture was polymerized for 68 hours at 39.5 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming was carried out for 2 hours at 195 ° C.

The foam thus obtained had a density of 97 kg / m ³ .

Example 8

500 g (5 parts by weight) of isopropanol and 200 g (2 parts by weight) of water were added as a blowing agent to a mixture of equal molar parts of 5620 g of methacrylic acid (56.2 parts by weight) and 4380 g of methacrylonitrile (43.8 parts by weight). In addition, 5 g (0.05 part by weight) of tert-butyl perbenzoate, 8 g (0.08 part by weight) of 2,2-azobisiso-2, 4-dimethylvaleronitrile, 5 g (0.05 part by weight) were added to the mixture. Parts) 2, 2-azobisisobutyronitrile and 5 g (0.05 parts by weight) of di-tert-butyl peroxide added as initiators. In addition, 1000 g (10.0 parts by weight) of dimethyl methane phosphonate (DMMP) and 2500 g (25.0 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) were added to the mixture as a flame retardant. Finally, the mixture contained 40 g (0.40 part by weight) of release agent (PAT 1037), 30 g (0.30 part by weight) of ZnO and 120 g (1.2 part by weight) of carbon black (KB 600, EC from Akzo Nobel).

This mixture was 92h at 39.5 ° C in one of two glass plates size 50 * 50cm and a 2.2cm thick Edge seal formed chamber poly erized. The polymer was then subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming took place at 185 ° C. for 2 hours.

The foam thus obtained had a density of 146 kg / m ³ . This foam was subjected to the tests set out in Table 1. This table also contains the data obtained.

Example 9

To a mixture of 6140 g (61.4 parts by weight) of methacrylic acid and 3860 g (38.6 parts by weight) of methacrylonitrile, 360 g (3.6 parts by weight) of formamide and 360 g (3.6 parts by weight) of water were added as blowing agents. Furthermore, 6.9 g (0.069 part by weight) of tert-butyl perbenzoate and 3.9 g (0.039 part by weight) of the mixture were tert. -Butyl perpivalate, 3.9 g (0.039 parts by weight) of tert-butyl per-2-ethylhexanoate and 9.9 g (0.099 parts by weight) of cumyl perneodecanoate were added as initiators. In addition, 990 g (9.90 parts by weight) of dimethyl methanephosphonate (DMMP) and 990 g (9.90 parts by weight) of expanded graphite (Nord Min 250 from Nordmann, Rassman GmbH & Co.) were added as a flame retardant. Finally, the mixture contained 15g (0.15 parts by weight) of release agent (PAT 1037), 70g (0.70 parts by weight)

Parts) ZnO and 337 g (3.37 parts by weight) Aerosil (Aerosil 200 from Degussa-Huls AG).

This mixture was polymerized for 92 hours at 40 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then subjected to a final polymerization of 17.25 h from 40 ° C. to 115 ° C. sufficient tempering program. The subsequent foaming took place for 3 hours at 200 ° C.

The foam thus obtained had a density of 40 kg / m ³ . This foam was subjected to the tests set out in Table 1. This table also contains the data obtained.

Comparative Example 1

A foam with a density of 71 kg / m ³ was produced in accordance with DE 33 46 060, 10 parts by weight of DMMP being used as the flame retardant.

For this purpose, a mixture of equal molar parts of 5620 g (56.2 parts by weight) of methacrylic acid and 4380 g (43.8 parts by weight) of methacrylonitrile, 140 g (1.4 parts by weight) of formamide and 135 g (1.35 parts by weight) of water was added as the blowing agent. Furthermore, 10.0 g (0.100 part by weight) of tert-butyl perbenzoate, 4.0 g (0.0400 part by weight) of tert-butyl perpivalate, 3.0 g (0.0300 part by weight) were tert of the mixture .- Butyl per-2-ethylhexanoate and 10.0 g (0.1000 parts by weight) of cumyl perneodecanoate added as initiators. In addition, 1000 g (10.00 parts by weight) of dimethyl methane phosphonate (DMMP) were added to the mixture as a flame retardant. Finally, the mixture contained 20 g (0.20 part by weight) of release agent (MoldWiz) and 70 g (0.70 part by weight) of ZnO.

Final polymerization 17.25 hours from 40 ° C to 115 ° C sufficient tempering program. The subsequent foaming took place at 215 ° C. for 2 hours.

The foam thus obtained had a density of 71 kg / m ³ .

Comparative Example 2

A mixture of 5700 g (57.0 parts by weight) of methacrylic acid and 4300 g (43.0

Parts by weight) methacrylonitrile 140 g (1.4 parts by weight) formamide and 135 g (1.35 parts by weight) water as a blowing agent. Furthermore, 10.0 g (0.100 part by weight) of tert-butyl perbenzoate, 4.0 g (0.040 part by weight) of tert-butyl perpivalate, 3.0 g (0.030 part by weight) were tert. -Butylper-2-ethylhexanoate and 10g (0.100 parts by weight) cumyl perneodecanoate added as initiators. In addition, 1000 g (10.00 parts by weight) of dimethyl methane phosphonate (DMMP) were added to the mixture as a flame retardant. Finally, the mixture contained 15 g (0.15 part by weight) of release agent (PAT) and 70 g (0.70 part by weight) of ZnO.

This mixture was polymerized for 92 hours at 40 ° C. in a chamber formed from two glass plates of size 50 * 50 cm and a 2.2 cm thick edge seal. The polymer was then subjected to a tempering program ranging from 40 ° C. to 115 ° C. for 17.25 hours. The subsequent foaming took place at 220 ° C. for 2 hours.

The foam thus obtained had a density of 51 kg / m ³ . This foam was subjected to the tests set out in Table 1. This table also contains the data obtained.

Comparative Example 3

The procedure was essentially the same as in the case of the

Comparative Example 1, except that the foaming took place at 210 ° C. and the density of the foam obtained was then 110 kg / m ³ .

Table 1

The values shown clearly show that the flame-retardant poly (meth) acrylimide materials according to the invention excellently meet the fire tests described above. It is particularly surprising slight increase in heat development for foams with high density.

Claims

claims

1. Composition for the production of

Poly (meth) acrylimide foam with reduced flammability, characterized in that the

Composition has expanded graphite.

2. Composition according to claim 1, characterized in that the composition has 5 to 50 wt .-% expanded graphite, based on the weight of the monomers.

3. Composition according to claim 1 or 2, characterized in that the composition contains further flame retardants.

4. Composition according to claim 3, characterized in that the further flame retardant is a phosphorus compound.

5. Composition according to claim 4, characterized in that the phosphorus compound is selected from phosphines, phosphine oxides, phosphonium compounds, phosphonates, phosphites and / or phosphates.

6. Composition according to claim 4, characterized in that a phosphorus compound of formula (I)

X-CH ₂ -P (0) (OR) ₂ (I),

where R is the same or different radicals from the

Group is methyl, ethyl and chloromethyl and X is a hydrogen or halogen atom, a hydroxyl group or a group F ^ O-CO-, wherein R ^{1 is} methyl, ethyl or Chloromethyl means, is used as a further flame retardant.

7. poly (meth) acrylimide molding composition for the production of moldings with reduced flammability, characterized in that the molding composition contains expanded graphite.

8. Shaped body made from a molding composition according to claim 7.

9. poly (meth) acrylimide foam obtainable by polymerizing and foaming a composition according to one or more of claims 1 to 6 or by foaming a molding composition according to claim 7.

10. A method for producing a poly (meth) acrylimide foam according to claim 9, characterized in that a mixture consisting of

(A) 20-60% by weight of (meth) acrylonitrile, 40-80% by weight of (meth) acrylic acid and 0-20% by weight of other vinylically unsaturated ones

Monomers, the components of component (A) giving 100% by weight;

(B) 0.5-15% by weight, based on the weight of components (A), of a blowing agent; (C) 1-50% by weight based on the weight of the

Components (A), Expandable Graphite; (D) 0.01 to 0.3 wt .-%, based on the weight of components (A), one

polymerization initiator; (E) 0-200% by weight, based on the weight of the

Components (A), usual additives polymerized to a plate and then foamed this polymer plate at temperatures of 150 to 250 ° C.

11. The method according to claim 10, characterized in that an aliphatic alcohol having 3 to 8 carbon atoms, urea, monomethyl or N, N'-dimethylurea is used as blowing agent.

12. The method according to claim 10 or 11, characterized in that an anti-settling agent is used as an additive.

13. The method according to claim 12, characterized in that carbon black or Aerosil is used as an anti-settling agent.

14. Layer material containing a layer of a poly (meth) acrylimide foam according to claim 9.