HK1080798B - Noise prevention plate consisting of acrylic glass - Google Patents

Description

Sound-insulating acrylic sheet

The present invention relates to acrylic sheets and also to their use as acoustic panels, in particular as components in noise barriers.

Noise-proof foundations, noise barriers or sound-proof facades have been used for many years to protect inhabitants from traffic noise. Foundations require more space and are therefore preferred for open areas, whereas noise-proof or sound-proof facades are used in urban areas for bridge constructions and often also for railway sections.

Materials that have been accepted in practice in recent years for space-saving noise barriers include wood, metal and cement in the opaque field, and glass materials and plastics that are customary in the transparent field.

Transparent noise barriers made of plastic materials are made in particular of polymethyl methacrylate (PMMA) or of molding compositions based on PMMA, since these materials not only have excellent transparency and excellent optical properties, but also provide excellent sound insulation and good physical and mechanical properties (resistance to riprap).

Of course, the relatively high price of the transparent noise barrier is a disadvantage, whereby transparent parts are generally only used in places which, in relation to the height of the pipe wall, do not completely separate the locomotive driver or passengers in the train compartment from the environment. This is used, for example, to avoid possible "tunnels" on bridges, wherein nowadays these noise barriers are also only partially transparent, particularly considerably due to the high price.

Thus, there is a great need for acrylic sheet parts that are low cost, space efficient, yet have excellent sound insulating properties and useful mechanical properties. The cost of these components should be as significantly lower as possible than the cost of known acrylic glass panels. Furthermore, there is a long felt need in practice for components that are opaque but can be easily combined with transparent sound-deadening acrylic sheets, and in particular can be used with consistent mounting and securing methods.

Another factor is that known transparent plastic acoustical panels are typically composed of acrylic sheets having dimensions of about 2 x 2 meters, which in larger noise barriers can provide a corresponding column spacing between one sound barrier component and the next. If the column spacing is to be increased, e.g. to 3X 2 or 4X 2 meters, stronger sheets are used. Nevertheless, wind load calculations show that even using acrylic sheets with a thickness of 25, 30 or 35 mm is not sufficient to meet the requirements for certain extreme wind loads, not to mention the high price of these rather thick acrylic sheets.

It is therefore also desirable to further improve the mechanical properties, such as the modulus of elasticity, of the novel sound-insulating sheet material when compared to known acrylic sheets for sound insulation, to obtain greater column spacing and thereby further reduce the overall cost of noise barriers.

It is another object of the present invention to provide a sheet material which is suitable for use as a sound-insulating member and which does not impair or only slightly impairs the excellent aesthetic properties of a noise barrier composed of a transparent acrylic sheet material.

It is another object of the present invention to provide sound-insulating sheets which have very high weather resistance and which can also be designed as self-cleaning systems if desired.

Finally, there is another problem in the sound-insulating sheet composed of plastic. If these sheets are used on the roadside, there is a serious danger of dangerous debris being formed or plastic parts being ignited when a motor vehicle collides with the soundproof parts. The danger resulting from the burning of debris or sound-deadening components can be very severe. There is therefore an urgent need to improve the safety level of the soundproofing sheet composed of plastic with respect to debris and fire.

The acrylic sheets described in the following description achieve these objects and others that, although not specifically mentioned, are obvious from or necessarily derived from the context discussed herein.

Useful variations of the sound-insulating sheet material of the present invention are also specifically explained in the following description.

Acrylic sheets of size or greater 2 x 2 m or greater and thickness in excess of 8 mm, preferably in excess of 12 mm, with threads, strips, grids or meshes of material incompatible with the acrylic sheets, embedded in the acrylic sheets for the attachment of the fragments at break, containing a fraction of opaque fillers ranging from 40% to 80% by weight of the total weight of the sheet (minus the weight of the embedded material), provide, in an unforeseen manner, opaque soundproofing sheet components usable in Noise Barriers (NB) which can be combined in an ideal manner with previously known transparent soundproofing acrylic sheets, and have numerous other, some of them very surprising advantages.

Herein, the outstanding mechanical properties of the acrylic soundproofing sheet of the present invention should be first discussed. For example, it was found that the tensile strength, elongation at break, elastic modulus (tensile), flexural strength, elastic modulus (flexural) value, and coefficient of thermal expansion in the opaque sheet of the present invention were all in part significantly superior to the corresponding values for the transparent acrylic sound-insulating material at the same sheet size and thickness.

The high elastic modulus of the opaque acrylic sound-insulating sheet of the present invention has proven to be very advantageous. Because the modulus of elasticity is higher when compared to a transparent sound insulating sheet composed of unfilled acrylic sheets, greater support or column spacing is possible when assembled as a noise barrier. The overall cost of the noise barrier can be reduced.

In addition, the NB sheets of the present invention can provide a significant reduction in sheet thickness at the current universal size when compared to known transparent NB acrylic sheets without having to accept the consequences of impaired mechanical and acoustic properties. Despite the reduced sheet thickness, the desired degree of sound insulation can be ensured by a high weight per unit area.

Also, fillers are generally significantly cheaper than acrylic sheet substrate materials, so high filler contents can also result in significant cost reductions.

The highly filled sheet of the present invention also has improved flame resistance, meaning that it can achieve a flame retardancy rating of ZTV LSW 88, and also a flame retardancy rating of B2, meaning that little smoke and fire spread occurs on fire. Surprisingly, however, it is possible to achieve a flame retardant rating of B1 using the opaque acoustical sheet (NT acoustical sheet) of the present invention which is composed of a highly filled acrylic sheet, provided that an appropriate filler such as aluminum hydroxide or the like is used.

Another highly exceptional property is that the sheet of the present invention can achieve the chip safety rating of clear acrylic sheets despite the higher proportion of filler, provided that a suitable chip tie system is used. Despite the high brittleness of highly filled plastic materials, all the requirements set for such systems can be met in the sheets according to the invention by, for example, embedded chip-bonding systems, such as preferably plastic-coated polyamide threads, steel cables or similar systems.

Finally, the quality requirements for the acrylic sheet matrix material are lower in the opaque sheets of the present invention than in conventional transparent NB sheets composed of acrylic sheets. This provides an unexpected opportunity for recycling. The opaque acoustical sheet itself, waste products produced, chipped material, acoustical sheet recovered after use over a period of time, and other manufacturing waste materials can be pulverized and ground to a desired particle size, preferably about 50 microns, and then used as a manufacturing raw material.

For the purpose of the present invention, the sound-insulating sheet composed of an acrylic sheet is an acrylic sheet which can be a component of a noise barrier as a sheet member.

The term "sheet" means a sheet-like structure having any geometric shape, which may be, for example, circular, angular, semi-circular, or have any other shape. However, the sheet is preferably square or rectangular. The corners or edges of the sheet may be rounded or flattened.

The sheet composed of acrylic sheets according to the present invention has a certain minimum size. Here the dimensions are 2 x 2 meters or more. The size of 3 × 2 meters or 4 × 2 meters is preferred because the filled acrylic sheet has high mechanical stability. However, as with any intermediate size, larger sizes may also be achieved, either directly during the preparation of the sheet, or by further processing of the cast sheet thereafter. If the invention relates to sheets which are not square or rectangular, a dimension of 2X 2 meters means that the circular or irregularly shaped sheet has or contains a correspondingly large amount of flat area, or circular or irregularly shaped sheets having at least 4 meters²Sheet area of (2).

The larger dimensions of the sheet material of the invention, such as a thickness of more than 8 mm, preferably more than 12 mm, are characteristic, which clearly distinguishes the sound-insulating sheet material of the invention from semi-finished or other smaller sheet materials. Thickness is a significant feature because the necessary degree of acoustic insulation can only be achieved by a suitable thickness. Typical thicknesses are for NB field sheets of more than 8 mm, preferably more than 10 mm, particularly preferably more than 12 mm, preferably in the range from 8 to 40 mm, advantageously in the range from 10 to 40 mm, more advantageously in the range from 12 to 35 mm, particularly preferably 15 to 30mm thick. However, sheets of 40 mm thickness or even greater may be manufactured for the intended purpose as desired, and may be larger or smaller in size for a particular application.

The plastic sheet of the present invention has a highly filled matrix composed of acrylic sheets. These sheets may be cast, for example, from a methyl methacrylate slurry. By "filled" acrylic sheet is meant an acrylic sheet that includes a filler. By "highly filled" is meant that the filler content is in the range of 40 to 80% by weight based on the total weight of the sheet consisting of the acrylic sheet. The "total weight" of the sheet means: for the purposes of the present invention, the total weight of all substances participating in the sheet structure is subtracted by the materials embedded for the joining of the fragments, such as threads, bands, nets and grids. If the filler content is less than 40% by weight, the loss of transparency is not proportional to the improvement in mechanical properties and the cost saving, whereas if the filler content is more than 80% by weight, the sheet may easily become brittle and crack, which means that the matrix loses its property of firmly binding the filler particles. Sheets having a filler content in the range of 50 to 60% by weight have a particularly balanced property profile.

The nature and shape of the filler present in the acoustical insulation sheet of the present invention can vary widely depending on the particular intended application. Fillers that may be advantageously used in the preparation of the sound-deadening sheet of the present invention include, inter alia, talc, dolomite, natural intergrowths of talc and dolomite, mica, quartz, chlorite, alumina, aluminum hydroxide, clay, silica, silicates, carbonates, phosphates, sulfates, sulfides, oxides, metal oxides, powdered glass, glass beads, ceramics, kaolin, porcelain, cristobalite, feldspar and/or chalk.

In principle, also preferred are fillers of the silanized type, since silanization can impart better adhesion to the matrix than non-silanized fillers.

Of particular interest are the types of fillers which are minerals, among which mica, chlorite or quartz, such as those produced by NaintschType, an intergrowth of talc and dolomite, in particular an intergrowth of white talc and pure dolomite, BC fine type from Naintsch, DorfnerPowdered crystalline quartz, Stauss, St.PoltenCELL microporous additive combination and NabaltecForm (aluminum hydroxide).

SE specialty supplements (intergrowth of talc and dolomite) at concentrations in the range of 40 to 80% are particularly advantageous. As mentioned above, sheets with higher filler concentrations have lower manufacturing costs and better mechanical properties (modulus of elasticity). However, upon ignition, the more highly filled sheet will exhibit less fire spread and less smoke generation.

The flammability of the sheet according to the invention can be further improved by using a mixture of a specific supplement of SE with aluminium hydroxide. In the case of fire, the aluminum hydroxide can have a self-extinguishing effect by elimination of water. The fineness of the aluminum hydroxide is also of particular importance here. Fine aluminum hydroxide is particularly suitable than coarse aluminum hydroxide because it can not only liberate chemically bound water, but also adsorbs bound moisture upon ignition.

The various fillers mentioned may be in a variety of forms. They may be spherical or non-spherical, with fibrous or platelet-like fillers, especially those having a flake geometry, being preferred. If the reinforcing filler present is in the form of flakes or needles, it is possible to obtain advantageous acrylic sheets for the NB sector with a particularly good combination of properties. The more lamellar the filler, the higher the impact strength of the sheet and the lower its modulus of elasticity.

When the filler particles used are lamellar fillers, a particular embodiment of the sheet prepared according to the invention results. For the purposes of the present invention, these are understood to be those fillers which exhibit a preferred orientation during the casting process (preparation of the sheet in the casting process, casting of the sheet).

The size of the filler particles also plays a role in determining the quality of the sheet of the invention. For example, the stiffness of the sheet can be controlled by using a filler of suitable size. The finer the filler, the higher the modulus of elasticity of the sheet and its impact strength. The filler particles used typically range in size from about 0.01 to about 100 microns. The mean particle diameter of the fillers used is advantageously in the range from 0.01 to 80 μm, in particular in the range from 0.05 to 30 μm, particularly advantageously in the range from 0.1 to 20 μm.

The finer the reinforcing filler used, the higher the stiffness and impact strength of the sheet. If a coarser filler is used, the resulting sheet is more brittle. A particularly advantageous acrylic sheet according to the invention is characterized in that the filler used has a residue of less than 2% by weight on a 20 μm sieve. It is particularly advantageous to use fillers in which the residue of the filler used is less than 2% by weight at 12 μm sieve.

By way of example, the sheets of the invention may be obtained by polymerization of a (meth) acrylate system in a casting process, preferably by a cell casting process or by a modification thereof, wherein the polymerizable system comprises:

A) a) 50 to 100% by weight of a (meth) acrylate

a1) 0 to 99.99% by weight of methyl (meth) acrylate

a2)C₂-C₄(meth) acrylic acid ester 0-99.99% by weight

a3)≥C₅0 to 50% by weight of (meth) acrylic acid ester(s) of

a4) 0.01 to 50 wt.% of a polyfunctional (meth) acrylate

b) Comonomer 0-50 wt%

b1) 0 to 50% by weight of a vinyl aromatic compound

b2) Vinyl ester 0-50 wt%

The components a) and b) are selected here such that they form, in total, 100% by weight of the polymerizable component A),

B) for 1 part by weight of A), from 0 to 12 parts by weight of a (pre) polymer which is swellable or soluble in A),

C) an initiator in an amount sufficient to cure the polymerizable component A),

D) a reagent for adjusting the viscosity of the system when appropriate,

E) conventional additives in amounts of up to 3 parts by weight, based on 1 part by weight of A), and

F) for 1 part by weight of the sum of binders (A) to E)), 0.33 to 4 parts by weight of filler,

and the viscosity of the polymerizable system prior to polymerization is greater than 0.1 Pascal-second (100 centipoise).

For the purposes of the present invention, it is desirable that the filler be uniformly distributed throughout the sheet. To achieve this distribution, for example, the viscosity of the (meth) acrylate system to be polymerized used to form the sheet is utilized. The sheets of the invention are preferably obtained by polymerization of (meth) acrylic systems having a viscosity of greater than 0.1 pascal-seconds (100 centipoise) before polymerization. Higher viscosity polymerization systems have a tendency to prevent settling of the filler during polymerization. The fineness of the filler can also be used to influence the settleability. The coarser filler has a tendency to settle, with the result that the sound-insulating sheet forms "pits". In addition to the use of fine fillers, this is eliminated exclusively by the use of thixotropic agents.

The present invention also includes a method of making an opaque acrylic sheet, wherein:

a) a polymerizable, filled (meth) acrylate composition is provided,

b) the composition provided is poured into a pre-prepared mould, in which the wire, strip, grid or mesh intended to be embedded has been placed,

c) polymerizing the composition in the mold at a temperature above room temperature to obtain a sheet and

d) the sheet is demoulded to obtain the product,

wherein the method is characterized in that

The viscosity of the polymerizable, highly filled (meth) acrylate composition is adjusted to a value greater than 0.1 pascal-seconds (100 centipoise) prior to polymerization in the mold.

A first advantageous variant of the process of the invention is characterized in that the viscosity of the polymerizable composition is controlled by varying the weight ratio of (pre) polymer to polymerizable monomer in the composition.

In addition to or in conjunction with this method, it may also be advantageous to control the viscosity of the composition by varying the proportion of viscosity modifier. These agents for adjusting, i.e. controlling, the viscosity are known per se to the person skilled in the art. For example, they include ionic, nonionic and zwitterionic emulsifiers.

Other advantageous agents or methods for influencing and/or adjusting the viscosity of the polymerizable composition include, inter alia, the following measures:

the viscosity of the polymerization system can be varied by adding regulators.

It may be advantageous to control the viscosity of the polymerization system by the mixing ratio of the (pre) polymer (pre-polymerization product) and the monomeric, polymerizable components in the polymerization system.

Wetting agent additives used, such as lecithin orEtc. may be used in amounts and in amounts that make possible the adjustment of the viscosity to the desired value.

The filler concentration itself influences the viscosity of the polymerization system, just like the filler properties or the properties of the filler mixture (particle size, oil number, surface treatment).

Conventional additives such as thixotropic agents (e.g. thixotropic agents)) The viscosity of the polymerization system is also changed.

The polymerization temperature can also be used to influence the viscosity of the system.

Finally, the concentration of the initiator and the polymerization kinetics also have an influence on the viscosity of the polymerization system and thus on the sedimentation of the filler.

In the opaque sound-insulating acrylic sheet produced with fillers (NT sound-insulating sheet), a reinforcement (thread, tape, net, grid) consisting of a material incompatible with the matrix material, preferably a plastic incompatible with the acrylic sheet, is introduced in the form of a sheet (grid, net) or a thread (thread, tape) into the acrylic matrix.

Herein, a material incompatible with the acrylic sheet matrix means that the matrix material and the embedded material are not mixed with each other, and do not form a phase, under the conditions of preparation and application of the sheet.

Thus, a wire, tape, grid or mesh composed of polyamide, polyester and/or polypropylene and embedded in a matrix composed of acrylic sheets is particularly suitable in one embodiment of the invention for binding fragments upon breakage of the sound-insulating sheet.

In another particular variant, the acrylic sheet of the invention is characterized in that it has polyamide threads embedded in a highly filled plastic matrix for linking the fragments at break.

These plastic sheets can be prepared in any manner known to those skilled in the art.

An example of such a method is to form a groove with two pre-cast plastic sheets, such as acrylic sheets (2000 mm x 1220 mm x 8 mm), by means of a circumferential seal having a thickness of 4 mm. Monofilament synthetic polymer threads, such as polyamide threads, with a diameter of, for example, 0.9 mm, are then tensioned coaxially or also deliberately non-coaxially in the grooves parallel to one another at a distance of 30mm each. The tank is then filled with a low viscosity cold-curing methacrylate resin comprising an external citrate-based plasticizer and a redox initiator system.

The intermediate layer is completely cured and the sheet is removed to provide a plastic sheet.

The NT sound insulating sheets of the present invention, comprised of opaque highly filled acrylic sheets, can also form useful stagnation systems at a lower cost. For the purposes of the present invention, the term immobilizer system refers to a device suitable for preventing an impact object, such as a motor vehicle, from penetrating the device. According to a preferred embodiment, the present invention immobilization system is effective in arresting the penetration of an object that impacts the system vertically, has a velocity of at least 5, preferably at least 7, meters per second, and has an energy of at least 5000 joules, preferably at least 7000 joules, through the system.

For this purpose, the NT sound-insulating sheet of the present invention comprises at least one embedded metal cord having at least partially a plastic layer between the surface of the metal cord and the transparent acrylic matrix. This provides, in a surprising and not easily foreseeable manner, an acoustic parking system which is particularly inexpensive to maintain and install. One factor to be taken into account here is that no additional installation steps are required and, in contrast to conventional parking systems, the noise barrier requires little maintenance.

The force to pull the steel wire out of the acrylic sheet matrix of the highly filled, opaque acrylic sheet is typically more than 50 newtons, preferably more than 100 newtons, without any restriction being caused thereby. This force can be determined in a known manner by loading the bare metal rope with force. The minimum force required to pull out the cord is defined as the pull-out force.

In a preferred embodiment, the acrylic sheet according to the invention is characterized in that it has a steel wire embedded in a highly filled plastic matrix for binding the splinters at break and acting as a stopper system, which wire is optionally coated with a plastic, preferably a plastic consisting of polyamide.

The sheet of the present invention is a poly (meth) acrylate sheet. These sheets have a high, preferably major amount, i.e. a rather high content, of 50% by weight or more of poly (meth) acrylate. Poly (meth) acrylates are polymers which are regarded as having structural units of the formula (I)

Wherein R is¹Is an organic radical, preferably C_1-6Alkyl, preferably C_1-4An alkyl group, a carboxyl group,

R²is hydrogen, C_1-6Alkyl, preferably hydrogen or C_1-4Alkyl, particularly preferably hydrogen or methyl,

n is a positive integer greater than 1.

C_1-4Alkyl groups include linear and branched alkyl groups containing 1 to 4 carbon atoms. Of particular interest are methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-methyl-1-propyl, sec-butyl, 2-methyl-2-propyl.

C_1-6Alkyl radicals being covered by C_1-4Radicals mentioned in the alkyl radicals and also radicals having 5 or 6 carbon atoms, such as preferably 1-pentyl, 2-pentyl, 3-pentyl, 2-dimethyl-1-propyl, 3-methyl-1-butyl, 3-methyl-2-butyl, 2-methyl-1-butyl, 1-hexyl.

Examples of compounds having the above-mentioned structural elements include, inter alia, polymethyl acrylate, polyethyl acrylate, polymethyl methacrylate, polypropyl acrylate, polybutyl acrylate, polypropyl methacrylate, polybutyl methacrylate and copolymers containing two or more of these types of polymers. For the purposes of the present invention, the first four compounds are preferred. Polymethyl methacrylate (PMMA) is particularly preferred.

In addition to chemical mixtures (random copolymers or block copolymers) resulting from the copolymerization of at least two substituted or unsubstituted acrylate monomers, such as methyl methacrylate-n-butyl methacrylate copolymers, it is also possible for the purposes of the present invention to use poly (meth) acrylate sheets consisting of copolymers containing up to 50% by weight of at least one other vinyl-containing unsaturated monomer which can be copolymerized with at least one substituted or unsubstituted acrylate monomer.

These examples include in particular methyl methacrylate-styrene copolymers or methyl methacrylate-butyl acrylate-styrene terpolymers.

Comonomers are optional ingredients or components, preferably present in minor amounts in the acrylic sheet in the form of copolymers containing them. Generally their choice is such that: they do not have any adverse effect on the properties of the poly (meth) acrylates to be used according to the invention.

The above comonomers can be used in particular to modify the copolymers in a desired manner, for example by increasing or improving the flowability if they are exposed to higher temperatures during processing of the copolymers, or by reducing the residual color in the copolymers or by using polyfunctional monomers in order in this way to introduce a certain or defined degree of crosslinking in the copolymers.

Monomers suitable for this purpose include, inter alia, vinyl esters, vinyl chloride, 1-dichloroethylene, styrene, alpha-methylstyrene and also various halogen-substituted styrenes, vinyl and isopropenyl ethers, dienes, such as 1, 3-butadiene and divinylbenzene. The color reduction of the copolymers is preferably achieved, for example, by using electron-rich monomers, such as vinyl ethers, vinyl acetate, styrene or alpha-methylstyrene.

Among the above comonomer compounds, aromatic vinyl monomers such as styrene or α -methylstyrene are particularly preferred.

Physical mixtures, so-called blends, are also preferably used for the poly (meth) acrylate sheets.

Furthermore, the poly (meth) acrylate sheet of the present invention may comprise conventional additives. Including, inter alia, antistatic agents, antioxidants, mold release agents, flame retardants, lubricants, dyes, flow improvers, fillers, light stabilizers and organophosphorus compounds, such as phosphites or phosphonites, pigments, thixotropic agents, UV stabilizers, weathering stabilizers and plasticizers.

Fillers are generally solid additives that differ essentially in their composition and structure from the poly (meth) acrylate matrix. These fillers may be inorganic or organic materials. They are well known to those skilled in the art.

Preference is given to using fillers which are inert under the conditions of depolymerization of the poly (meth) acrylates. For the purposes of the present invention, fillers which are inert under the conditions of depolymerization of the poly (meth) acrylates are substances which have no substantial adverse effect on the depolymerization reaction of the (meth) acrylate polymers or which do not make it possible at all. This property of the filler allows for simple recycling of the poly (meth) acrylate sheet.

Poly (meth) acrylates, especially polymethyl methacrylate, are one of the few plastics that are well suited for direct chemical recycling. This means that when these polymers are appropriately heated they can decompose completely at a certain temperature and pressure to give the corresponding monomer units (depolymerization). For example, various continuous and batch processes are described in the literature and patent specifications to depolymerize polymethyl methacrylate (PMMA) and recover the resulting methyl methacrylate monomer by heat treating acrylic sheet waste at temperatures > 200 ℃, condensing the resulting monomer vapors and processing the crude monomer. The method most commonly used in industry is to fill a tank partially filled with lead with a polymeric material and heat the tank from the outside. When the temperature exceeds 400 ℃ or above, the polymeric material depolymerizes and the resulting monomer vapor is piped to a condenser where it is condensed to form a crude liquid monomer. A similar depolymerization process is also disclosed, for example, in DE-A2132716.

The sheets according to the invention are obtained, for example, by polymerizing a (meth) acrylate system in a casting process, preferably by the cell casting process, the rotoro process or other variant cell casting process, wherein the polymerizable system comprises components A) to F) given above.

Component A) is the essential constituent of the (meth) acrylate system to be polymerized.

The use of the components included in parentheses is optional, and therefore, (meth) acrylate represents acrylate and/or methacrylate.

The monomer component A) comprises at least 50% by weight of (meth) acrylates, of which monofunctional C-containing monomers are preferred₁-C₄(meth) acrylate ester of an ester group. Longer chain esters, i.e. those having C₅Or longer chain ester groups, limited to 50% by weight in component A). Component A) preferably comprises at least 40% by weight of methyl methacrylate.

The long-chain (methyl) acrylate in a certain amount can make the system have better impact resistance. Although these esters thus make the sheet more flexible, they make the sheet softer, and thus the use properties are limited when the amount exceeds 50% by weight.

In addition to the (meth) acrylates, component A) may also comprise further comonomers, the proportion of which is limited to 50% by weight. Of these comonomers, vinylaromatic and/or vinyl esters can be present in component A), in each case up to 50% by weight. Higher proportions of vinylaromatic compounds are difficult to copolymerize and can lead to delamination of the system. Higher proportions of vinyl ester may be insufficient for curing at low temperatures and tend to increase shrinkage.

Component A) preferably consists of 80 to 100% by weight, particularly preferably 90 to 100% by weight, of (meth) acrylic esters, since the use of these monomers gives sheets with excellent processing properties and use properties. C in the (meth) acrylic esters of component A)₂-C₄The proportion of esters is preferably limited to 50% by weight, and the maximum amount of these esters in component A) is preferably 30% by weight, particularly preferably 20% by weight. Thereby forming a very flexible sheet.

Particularly suitable monofunctional (meth) acrylates are methyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyltriethylene glycol methacrylate, hydroxypropyl methacrylate.

Particularly suitable comonomers are vinyltoluene, styrene, vinyl esters.

In component A), styrene is preferably limited to a maximum of 20% by weight, since higher contents can cause problems during the polymerization.

Polyfunctional (meth) acrylates are also necessary in component A). The polyfunctional (meth) acrylate is particularly useful for reducing the water absorption of the sheet by its crosslinking action in the polymerization reaction. The polyfunctional (meth) acrylates are preferably used in amounts of from 0.1 to 30% by weight, particularly preferably from 0.2 to 5% by weight, in component A) of the (meth) acrylate system. Polyfunctional (meth) acrylates are used for polymer bonding between linear molecules. This can affect properties such as flexibility, scratch resistance, glass transition temperature, melting point or curing progress.

The polyfunctional (meth) acrylates preferably used include in particular:

(1) difunctional (meth) acrylates

A compound of the formula:

wherein R is hydrogen or methyl, n is a positive integer from 3 to 20, such as propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, hexylene glycol di (meth) acrylate, octylene glycol di (meth) acrylate, nonylene glycol di (meth) acrylate, decylene glycol di (meth) acrylate, or eicosylene glycol di (meth) acrylate, and compounds of the formula:

wherein R is hydrogen or methyl, n is a positive integer from 1 to 14, such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dodecaethylene glycol di (meth) acrylate, tetradecanethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, or tetradecaneylene glycol di (meth) acrylate; and glycerol di (meth) acrylate, 2 '-bis [ p- (. gamma. -methacryloxy-. beta. -hydroxypropoxy) phenylpropane or bis-glycidyl methacrylate (Bi s-GMA), bisphenol A dimethacrylate, neopentyl glycol di (meth) acrylate, 2' -bis (4-methacryloxypolyethoxyphenyl) propane having 2 to 10 ethoxy groups per molecule, and 1, 2-bis (3-methacryloxy-2-hydroxypropoxy) butane.

(2) (meth) acrylic acid esters with tri-or tetrafunctional groups

Trimethylolpropane tri (meth) acrylate and pentaerythritol tetra (meth) acrylate.

Preferred conventional multifunctional (meth) acrylates include especially triethylene glycol dimethacrylate (TEDMA), trimethylolpropane Trimethacrylate (TRIM), 1, 4-butanediol dimethacrylate (1, 4-BDMA), ethylene glycol dimethacrylate (EDMA).

Other preferred components of the (meth) acrylate systems to be used according to the invention are polyfunctional (at least difunctional) (meth) acrylates.

Component B) is an optional component, but its use is very preferred.

In principle, B) can be provided using two different methods. In one aspect, B) is mixed with A) in the form of a polymeric substance. Alternatively, A) may be prepolymerized to produce a so-called slurry. The syrup itself then comprises the monomer component from group a) and the polymer component from group B) mixed with each other.

To adjust the resin viscosity and the overall flowability of the system and to accelerate the curing reaction, a polymer or prepolymer B) may be added to component A) as described. The (pre) polymer may be swellable or soluble in A). From 0 to 12 parts of prepolymer B) are used per 1 part of A). Poly (meth) acrylates are particularly suitable, where they can be used in the form of solid polymers dissolved in a), or in the form of so-called syrup, i.e. a partially polymerized mixture of suitable monomers. Polyvinyl chloride, polyvinyl acetate, polystyrene, epoxy resins, epoxy (meth) acrylates, unsaturated polyesters, polyurethanes or mixtures of these substances are suitable. For example, these polymers may impart special flexibility, shrink control, or act as stabilizers or flow promoters.

1 part of A) is preferably used from 2 to 11 parts of B). 1 part of A) is particularly preferably used from 4 to 10 parts of B). 6 to 9 parts of (pre) polymer are optimally selected and mixed with 1 part of polymerizable monomer A). Preferably the (pre) polymer B) is dissolved in A).

In a preferred embodiment, the weight ratio of component B) to A) of the adhesive is in the range from 1: 1 to 12: 1. Within this range, a desirable balance of characteristics can be obtained.

A particularly advantageous weight ratio of B) to A) is in the range from 5: 1 to 12: 1.

Component B) ((pre) polymer) may be any polymerization product. Prepolymers are particularly advantageous, but may also be a suspension polymer, emulsion polymer and/or ground material recovered from a recycling process. In the simplest case, a methyl methacrylate prepolymer having a monomer conversion of 8 to 10 mol% (in mol) is used.

The (pre) polymer B) may be a copolymer, wherein the stiffness and flexibility of the sheet may be influenced by the nature and amount of comonomer in the (pre) polymer B). Comonomers which can be used to participate in the formation of the corresponding (pre) polymers B) include, in particular, acrylates and methacrylates other than Methyl Methacrylate (MMA), vinyl esters, vinyl chloride, vinylidene chloride, styrene, alpha-methyl-styrene and the various halogen-substituted styrenes, vinyl ethers and isopropenyl ethers, dienes, such as 1, 3-butadiene and divinylbenzene.

Examples of preferred comonomers instead of methyl acrylate are ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, propyl acrylate, propyl methacrylate, methacrylic acid, ethyltriethylene glycol methacrylate, hydroxypropyl methacrylate.

Component C) is an essential component and is indispensable for the curing reaction (polymerization reaction) of the polymerizable system.

The polymerization reaction may proceed according to a radical mechanism or an ionic mechanism, with radical polymerization being preferred. It can be carried out thermally, with radiation and initiators, with initiators which form free radicals being preferably used. The individual conditions of the polymerization depend on the monomers and initiator systems selected and are known to the person skilled in the art.

Preferred initiators include, in particular, azo initiators which are known to the person skilled in the art, such as azobisisobutyronitrile or 1, 1-azobiscyclohexanecarbonitrile, but also peroxides, such as methyl ethyl ketone peroxide, acetylacetone peroxide, ketone peroxides, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, 2, 5-bis (2-ethyl-hexanoylperoxide) -2, 5-dimethylhexane, tert-butyl 2-ethylhexanoate peroxide, tert-butyl 3, 5, 5-trimethylhexanoate peroxide, 1-bis (tert-butylperoxy) cyclohexane, 1-bis (tert-butylperoxy) -3, 3, 5-trimethylcyclohexane, cumene hydroperoxide, 1-azobiscyclohexanecarbonitrile, Tert-butyl hydroperoxide, dicumyl peroxide, bis (4-tert-butylcyclohexyl) peroxydicarbonate, mixtures of two or more of the abovementioned compounds with one another and mixtures of the abovementioned compounds with compounds which are not mentioned and which likewise form free radicals.

Redox systems can also be used, among which pituitous systems in organic solvents or aqueous solutions or suspensions are also known and can be used. One such system is available under the trademark AkzoThus obtaining the product.

Mixtures of initiators having stepped half-lives are also possible. In this way the polymerization reaction can be better controlled and local irregularities eliminated, giving more uniform results. This method also makes it possible to shorten the post-polymerization time (heat treatment of the sheet in a heating chamber).

The amount of component C) can vary within wide limits. It depends on the composition of the monomers, the nature and amount of the (pre) polymer and on the desired polymerization temperature and the desired molecular weight of the polymer to be prepared. For example, for products having a molar mass of from 100000 to 1000000 g/mol (weight-average molar mass), the initiator used per mole of polymerizable monomer system component has a prediction of from 1X 10^-5To about 1X 10^-6And (3) mol. The molar mass of the polymer is preferably from 650000 to 800000 g/mol.

Component D) is an optional constituent of the polymerizable (meth) acrylate system, but preferably it is present in the system. Examples are emulsifiers. Lecithin is preferred. The amount of substance used can vary within wide limits. For 1 part by weight of A), preferably from 0.01 to 1 part by weight of D). It is particularly preferred to use from 0.1 to 0.2 parts by weight of D) for 1 part by weight of A).

Component E) is optional. They are customary additives known per se, examples of which are listed above. E) In particular those which do not fall within F). Also included are non-reinforcing fillers, such as pigments and the like, which particularly preferably have a particle size smaller than that of the filler of component F). The average particle diameter of the fillers used in accordance with E) is preferably in the range of less than 10 μm, advantageously in the range of less than 5 μm, particularly preferably less than 1 μm, most preferably less than 0.01. mu.m. The average particle size ratio of fillers E) to F) is advantageously in the range from 1: 3 to 1: 1000, preferably in the range from 1: 5 to 1: 100 and particularly preferably in the range from 1: 10 to 1: 50.

Component F) is necessary. Further details of this component have been described above.

Examples

1. Exemplary sheet production by convection Heat transfer oven method (example 1)

1.1 Structure of the mold

Two Sekurit glass plates were used as molds. A PVC seal was placed between the glass plates of the mold. Monofilament polyamide wires of diameter 2 mm were then clamped in the formed grooves at a pitch of 30mm each. The three sides of the glass sheet were then clamped with clamps. The width of the groove can be varied by using sealing strips of different thicknesses. For example, the gap thickness of the groove is about 15 mm. The fourth side is sealed after filling with material. The sheet system thus sealed was placed horizontally and placed in a convection heat transfer oven.

1.2 Poly (meth) acrylate systems for filling molds

Prepolymer 1 is an MMA-based syrup in which methyl methacrylate has been prepolymerized in known manner to about 10% conversion (90% by weight of residual monomer). The viscosity of the prepolymer was about 450 cps.

The 2 crosslinker is triethylene glycol dimethacrylate (temma).

3 AVN is the radical generator azo valeronitrile.

4 SER AD FA192 refers to a phosphate derived from ethoxylated nonylphenol phosphate.

5*P is from CibaOne light stabilizer of GmbH is 2- (2-hydroxyphenyl) benzotriazole.

6 SE-Super from Naintsch, A-8045Graz-Andritz, Austria. This is an intergrowth of white talc and pure white marble, which had a composition of 17% silica, 22% magnesia, and 24% calcium oxide according to chemical analysis, and had a weight loss of 37% after ashing at 1050 ℃ for 1 hour. The dolomite content (Leco) was 75%. There was a 2.0% sieve residue at 12 μm on the sieve run according to DIN 66165.

1.3 preparation of the mixture

The desired fillers and additives are dispersed in about 1/3 a of the desired prepolymer (syrup). For this purpose, the dispersant is first metered in, followed by the desired additives, such as UV stabilizers, crosslinkers, heat stabilizers, etc., and also the fillers.

The solution was dispersed in a stirred vessel capable of cooling and emptying for at least 30 minutes. The dispersion temperature during this process should not exceed 50 ℃. After dispersion, the mixture was cooled to room temperature and diluted with the remaining slurry before the desired catalyst was added as a solution. The solution was then stirred under vacuum for a further 30 minutes.

1.4 filling in the tank and polymerization, and demolding

Injecting the mixture into a mold; the charge was injected directly from the mix tank through a 25 micron bag filter into the mold. The sheet is polymerized in a convection process. About 90% conversion is completed during the main polymerization reaction. The sheets were subjected to a postpolymerization in a tempering oven at 120 ℃. After the sheet had cooled, the upper glass plate was removed from the bath and the poly (meth) acrylate sheet was removed.

2 to 4

Sheets were further manufactured according to example 1. In examples 2 to 4, in particular the formulation of the poly (meth) acrylate system was changed. The system used had the following composition:

compositions of (meth) acrylate systems 2 to 4, in each case in parts by weight:

7 Martinel ON 310 is an aluminum hydroxide species from Martinswerke GmbH. The average particle size is 9 to 13 microns. Oil absorption of 24 to 28 cm³100 g. The water content is less than 0.3 percent.

Various tests were performed on NT SD sheets of the invention, the sheet thickness being 15 mm and the two-dimensional dimensions 2 × 2 m. Specific physical properties were calculated and compared to those calculated for the same size transparent sheet.

The results show that the sheets according to the invention meet all relevant criteria. The sheet material of the present invention has significantly superior mechanical properties to the transparent sound insulating material with embedded nylon filaments, the so-called LSCC material. The use of a three-sided clamping arrangement with a column spacing of 5 x 2 meters can be accomplished by using a 35 mm thick NT SD. This is not possible with LS CC materials of 35 mm thickness because the deflection under load and stress values would exceed the allowable values. With four sides clamped, a column pitch of 5 x 2 meters can be achieved by using NT SD material of the invention even with a thickness of only 12 mm.

The inventive sheet according to example 4 was subjected to flame retardancy testing in accordance with DIN4102B 1. These flame retardancy test requirements are fully met with DI N4102-B1. This means that the highly filled NT SD sheets of the invention have low flammability.

The sheet according to the invention of example 4 was also subjected to a fracture test. For this purpose, the above-mentioned soundproofing members were placed on four wooden pillars (about 860 mm high) and they were not clamped or fixed. A wooden mat having dimensions of 1200 × 1200 × 140 (length × width × height) is placed thereon to protect the ground.

A cylindrical metal weight weighing 400 kg was dropped from 1500 mm above the sound-damping member to the center of the member. The impact kinetic energy of the weight was 5.89 joules and the velocity was 5.42 m/s (19.5 km/h). The metal weight has a radial line (radius) at the point of impact. When this metal weight is impacted, the acrylic sheet breaks in a typical manner. But no free fragments are generated and instead all acrylic sheet fragments are joined by embedded threads. This result is seen as highly surprising for highly filled systems.

Claims (21)

1. Acrylic sheet for use as an opaque soundproofing member in an anti-noise barrier, wherein the sheet has a size of 2 x 2 m or more and a thickness of more than 8 mm, and wires, bands, grids or meshes made of a material incompatible with the acrylic sheet are embedded in the acrylic sheet for binding fragments when the sheet is broken, characterized in that the proportion of filler is 40 to 80% by weight based on the total weight of the sheet excluding the weight of the embedded wires, bands, grids or meshes.

2. The acrylic sheet according to claim 1, characterized by a thickness in the range of more than 8 mm to 40 mm.

3. The acrylic sheet according to claim 1, characterized by a thickness in the range of more than 10 to 35 mm.

4. The acrylic sheet according to claim 1 or 2, characterized in that the thickness is in the range of 12 to 35 mm.

5. Acrylic sheet according to claim 1 or 2, characterized in that the proportion of filler is in the range of 50 to 60% by weight, based on the total weight of the sheet.

6. Acrylic sheet according to claim 1 or 2, characterized in that the filler in the sheet is substantially homogeneously distributed.

7. Acrylic sheet according to claim 1 or 2, characterized in that the filler comprises talc, dolomite, natural intergrowths of talc and dolomite, mica, chlorite, aluminium hydroxide, clay, silica, silicates, carbonates, phosphates, sulphates, sulphides, metal oxides, powdered glass, glass beads, ceramics, kaolin, cristobalite, feldspar and/or chalk.

8. The acrylic sheet according to claim 7, wherein the ceramic is porcelain.

9. The acrylic sheet according to claim 1 or 2, wherein the filler particles used are a lamellar filler.

10. Acrylic sheet according to claim 1 or 2, characterized in that the filler used has an average particle size in the range of 0.01 to 80 μm.

11. Acrylic sheet according to claim 1 or 2, characterized in that the filler used has an average particle size in the range of 0.05 to 30 μm.

12. Acrylic sheet according to claim 1 or 2, characterized in that the filler used has an average particle size in the range of 0.1 to 20 μm.

13. Acrylic sheet according to claim 1 or 2, characterized in that the filler is an intergrowth of talc and dolomite, optionally in a mixture with aluminium hydroxide.

14. The acrylic sheet according to claim 1 or 2, obtained by polymerizing a (meth) acrylate system in a casting process, wherein the polymerizable reaction system comprises:

A) a) 50 to 100% by weight of a (meth) acrylate

a1) 0 to 99.99% by weight of methyl (meth) acrylate

a2)C₂-C₄0 to 99.99% by weight of (meth) acrylic acid ester(s) of

a3)≥C₅0 to 50% by weight of (meth) acrylic acid ester(s) of

a4) 0.01 to 50 wt.% of a polyfunctional (meth) acrylate

b) Comonomer 0-50 wt%

b1) 0 to 50% by weight of a vinyl aromatic compound

b2) Vinyl ester 0-50 wt%

The components a) and b) are selected here such that they form, in total, 100% by weight of the polymerizable component A),

B) for 1 part by weight of A), from 0 to 12 parts by weight of a (pre) polymer which is swellable or soluble in A),

C) an initiator in an amount sufficient to cure component A),

D) optionally, an agent for adjusting the viscosity of the system,

E) conventional additives in amounts of up to 3 parts by weight, based on 1 part by weight of A),

and

F) for 1 part by weight of the sum of the binders A) to E), 0.33 to 4 parts by weight of filler,

and the viscosity of the (meth) acrylate system prior to polymerization is greater than 0.1 Pascal-second (greater than 100 centipoise).

15. The acrylic sheet according to claim 10, which is produced by a cell casting process.

16. Acrylic sheet according to claim 1 or 2, characterized in that it is a chip at the moment of fracture of the coupling, having steel wires already embedded in a highly filled plastic matrix and, optionally, the steel wires are covered with plastic.

17. Acrylic sheet according to claim 16, characterized in that said steel wires are coated with polyamide plastic.

18. A method for producing the acrylic sheet according to any one of claims 1 to 17, comprising:

a) a polymerizable filled (meth) acrylate composition is provided,

b) the composition provided is poured into a pre-prepared mould, in which the wire, strip, grid or mesh intended to be embedded has been placed,

c) polymerizing the composition in the mold at a temperature above room temperature to obtain a sheet and

d) the sheet is demoulded to obtain the product,

it is characterized in that

The viscosity of the polymerizable, highly filled (meth) acrylate composition is adjusted to a value of greater than 0.1 pascal-seconds prior to polymerization in the mold.

19. A method according to claim 18, characterized in that the viscosity of the composition is controlled by varying the weight ratio of (pre) polymer to polymerizable monomer in the composition.

20. A method according to claim 18 or 19, characterized in that the viscosity of the composition is controlled by varying the proportion of viscosity modifier.

21. Use of the acrylic sheet according to any one of the preceding claims 1 to 17 as an opaque sound-insulating member in a noise barrier.