CH617887A5 - Laminated material and its manufacturing process - Google Patents

Abstract

The material comprises a plate of poly(methyl methacrylate) adhering directly, by at least one of its faces, to a layer of crosslinked polyester enclosing a fibrous reinforcement or a filler. This layer is obtained by spraying onto the plate a composition comprising the liquid polyester, its catalyst and its accelerator, together with the reinforcement or the filler. In order to improve the adhesion of the cured layer on the plate, a homopolymer polyester is used and poly(vinyl acetate) is added to it in a quantity such that the shrinkage of the polyester is compensated for. This material can be used for the manufacture of moulded articles.

Description

The present invention relates to a laminated material, based on polymethyl methacrylate and polyester resin, as well as its manufacturing process.

Patent FR No. 1152576 already relates to a process for manufacturing laminated materials by welding between a polyester surface and a surface containing acrylic groups; to this end, it has been proposed to use an intermediate layer of reinforced polyester (fibrous material or silicone fabric), using as polyester crosslinking agent, a monomer containing acrylic groups, then to bring the surfaces to be welded into contact then the polyester surface is still incompletely polymerized, and to complete the polymerization by crosslinking of the polyester while keeping the two surfaces in contact. The polymerization operation can be carried out hot (around 70 ° C approximately) or cold (in the presence of cobalt naphthenate). Complex materials of the aforementioned type are also known in which suitable solvents are sprayed onto the acrylic surface before the polyester is put in place.

US Patent No. 3,832,268 describes a reinforced plastic structure, comprising a polymethyl methacrylate plate onto which a ternary polyester unsaturated methacrylic acid styrene composition is sprayed. Methacrylic acid helps promote adhesion. Due to its composition, the polyester resin used to manufacture this plastic article cannot exhibit compensated shrinkage properties. The adhesion of the individual layers of the structure is therefore defective in many applications.

All of these known materials have improved mechanical strengths; however, their manufacture is relatively complicated, inter alia because of the number of molds required, and their cohesion is frequently insufficient to avoid delamination.

The licensee sought to overcome these drawbacks and to improve the properties and qualities of such complex materials, by simplifying their manufacture; it has in particular proposed to obtain a complex material, based on reinforced and / or charged polyester resin, and on polymethyl methacrylate, not comprising the use of particular solvents.

To this end, the subject of the invention is the material defined in claim 1 and the process for manufacturing this material, defined in claim 7.

A polyester resin with compensated shrinkage leads, after polymerization, to a less significant shrinkage phenomenon than that caused by a conventional polyester resin, which makes it possible to substantially improve the adhesion between the polyester and the polymethyl methacrylate plate. In the case of a conventional polyester, the shrinkage is 8%; it follows that no bridging takes place between the polymethyl methacrylate plate and the polyester and that the adhesion is then zero.

Any type of polymethyl methacrylate can be used. Indeed, the quality of the polymethyl methacrylate plate does not influence the adhesion of the polyester composition.

Polymethyl methacrylate may for example be that manufactured and placed on the market under the trade name Altuglas by the licensee. It is advantageously of the Altuglas -series 8000 type suitable for deep thermoforming. Polymethyl methacrylate preferably has a low molar weight of the order of 800,000, for example.

According to an essential characteristic of the method according to the invention, a resin is used, as polyester resin, the polyvinyl acetate content of which is adapted to compensate for shrinkage during molding.

The amount of polyvinyl acetate contained in the polyester is not critical. However, in the case of a spraying of said polyester on the polymethacrylate plate, there may be a problem of viscosity. It is then preferable that the content of polyvinyl acetate in the polyester does not exceed 10% by weight.

In a preferred embodiment, the polyester contains by weight 67% of polyester resin, 27% of styrene and 6% of polyvinyl acetate. The polyester then has a shrinkage which does not exceed 3%. The polyester resin itself is obtained in a known manner, for example from a mixture of monomers contained in

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617,887

of maleic anhydride, phthalic anhydride, propylene glycol and diethylene glycol.

The reinforcing fiber used is advantageously glass fiber, for example cut to a length of between approximately 30 and 40 mm. The fiberglass can also be in the form of fabric and / or mat (weft and warp, of the Roving type for example). Fiberglass can be present at a rate of at most 30% of the weight of polyester.

According to another embodiment of the invention, the laminated material advantageously contains as filler calcium sulphate, for example dry plaster, at a rate of 19 to 25% of the weight of polyester, which improves the bonding of the layers .

The polyester further contains a catalyst and an accelerator which can be benzoyl peroxide and dimethylaniline, respectively; it should be noted in this regard that methyl ethyl ketone peroxide and cobalt naphthenate should preferably be avoided as catalyst and accelerator respectively, because, not only do they not give a polymerization fast enough to be industrial, but above all they give resistance tensile strength of the order of 30 kg / cm2, far below the required standard.

The method according to the invention makes it possible to obtain a material having the standard of 45 kg / cm 2 of tensile strength for the attachment of the laminated complex to the skin thermoformed in polymethyl methacrylate.

Note that, in the process of the invention, it is not intended to treat the acrylic surface by spraying various solvents before spraying the polyester / reinforcing fiber composition. This absence of treatment is an advantageous feature of the invention.

According to the invention, the operation is preferably carried out under the following conditions: for a given weight of polyester resin, approximately 1.5% by weight of benzoyl peroxide (catalyst) is used, 1.2% by weight of dimethylaniline (accelerator) , 15 to 25% by weight approximately of calcium sulphate and 0 to 30% approximately by weight of glass fiber, from 30 to 40 mm in length. Calcium sulfate is advantageously present in an amount of 20% by weight.

The polyester and glass fiber layers are applied by conventional methods, for example by spraying (in particular with a spray gun) or by injection.

The laminate material according to the invention finds a particularly advantageous use in the manufacture of molded articles, such as sanitary articles (sinks, sinks, baths, etc.). The articles obtained have very high mechanical properties. Thus, the layered layer of reinforced and charged resin adheres strongly to the support of polymethyl methacrylate, the resistance to tearing being at least equal to 45 kg / cm 2.

The invention is illustrated by the following examples:

Example 1:

This example relates to an embodiment of the method of the invention by projection.

A sheet of polymethyl methacrylate of the Altuglas type was previously thermoformed by the usual means.

• Polyester is a resin commercially known as Norsodyne 213 FM, manufactured by the company CDF Chimie (France). This resin, which is a compensated shrinkage homopolymer, has the following characteristics:

a) Physico-chemical

Before polymerization:

Density in liquid state (20 ° C) 1.07

Viscosity at 25 ° C 3.5-4.5 Po

Apha 40-150 hazen coloring

SPI reactivity;

- Gel 5'30-7 '

- 8'-10 'polymerization

- Exothermic peak 185-200 ° C

After polymerization:

Solid density (20 ° C) 1.10

Volume shrinkage 3%

Barcol hardness 32-34

5.

b) Mechanics:

Impact resistance (Dynstat-cemp) 2.5 kg / cm / cm3

Flexural strength (Dynstat-cemp) 7.6 kg / mm2

Flexural modulus (Haake) 36000 kg / cm2 io Bending temperature under load

(ASTM 648-56 standard) 91 ° C.

The polyester resin which contains 67% polyester, 27% styrene and 6% polyvinyl acetate, loaded with 20% CaSO4 relative to the resin, is sprayed onto the polymethyl methacrylate plate. Then a mixture of the same loaded resin and glass fibers is sprayed and finally glass fiber alone to obtain a total thickness for the laminate of 3.9 mm.

20 Example 2:

A polymethyl methacrylate plate of the stretched Altuglas type (manufactured and marketed by the company Altulor) is used, 0.8 mm thick. Unsaturated polyester resin containing 67% polyester, 27% styrene and 6% polyvinyl acetate, loaded with 20% CaSO4 relative to the resin, is sprayed onto this plate. Then a mixture of the same loaded resin and glass fibers is sprayed and finally glass fiber alone, to obtain a total thickness for the laminate of 3.9 mm.

After complete polymerization, the laminated material has the characteristics given in the table below.

Example 3:

The stratification is carried out in the same way as in Example 1 by incorporating during the spraying two layers of glass mat of 450 g / m2. „

After complete polymerization, the laminated material whose total thickness is 3.6 mm has the characteristics given in the table below.

(Finally patent table)

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Example 4:

This example relates to the resistance to mechanical shock and to thermal shock of the laminated material according to the invention.

On a 3 mm plate of polymethyl methacrylate (Altuglas 8000) with a free monomer content of less than 1%, 0.5% of plasticizer and 0% of lubricant, a method was applied according to the invention. 0.3 mm layer of polyester containing polyvinyl acetate (Norsodyne 213 FM), then successive layers of this polyester, more plaster (20%), more fiberglass (30%), then fiberglass not wet, to a total thickness of approximately 1.2 mm of polyester / filler / glass complex. Beyond this thickness of approximately 1.2 mm, the finished complex material reveals an orange peel or a hammered appearance. It has been found that the application of a 600 g / m2 mat pre-layer or / two 450 g / m2 mat pre-layers avoids this defect.

6o The finished material practically does not depend on the granulometry and the water content of the calcium sulphate, the Altuglas plate or skin must itself be preferably cold when the polyester is sprayed.

The finished material has excellent resistance to mechanical impact; it resists the shock of a mass of 5 kg falling from a height of 1 m. The test piece is considered to be good if the polymethyl methacrylate sheet does not have a fracture and if there is no separation of the laminate. We accept delamination

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in the zone. It is worth noting that an enamelled cast iron sink is destroyed by a mass of 1 kg falling from 1 m.

• 4.

The laminated material also has good resistance to thermal shock: steam and hot water were sprayed at 85 ° C. at the rate of a jet every 30 s for 2 h, in tanks; the tanks were then full and the water temperature of

55 ° C; no separation between the Altuglas and the laminate was noted.

For the implementation of the process, it is advantageous to provide a fiber deflector to avoid too early mixing of the fiber jet and the resin jet and to adjust the axes of the fiber and resin jets so that it fibers and resin overlap on the Altuglas plate.

Board

Characteristics

AFNOR standard

Unit

Laminated material according to the invention

example 1

example 2

Flexural strength

51001

N / mm2

154

134

Flexural module

51001

N / mm2

5570

4880

Charpy impact resistance

51035

J / cm3

1.8

2.0

Tensile strength

57001

N / mm2

84

79

Elongation at break

57001

%

2.6

2.7

Shore D hardness

ISO R 868

-

86

86

Water absorption

51002 A

mg

91

88

R

Claims (13)

617,887 CLAIMS 1. A laminated material comprising a polymethyl methacrylate plate integral with a layer comprising a crosslinked polyester, a fibrous reinforcement and / or a filler, characterized in that said polymethyl methacrylate plate adheres directly to at least one face. said layer, in that the polyester is a homopolymer and in that said layer additionally contains polyvinyl acetate. 2. Laminated material according to claim 1, characterized in that said layer contains up to 10% by weight of polyvinyl acetate. 3. Laminated material according to claim 1, characterized in that said layer contains a fiber reinforcement. 4. Laminated material according to claim 3, characterized in that the reinforcement is glass fiber, present at a rate of at most 30% of the weight of polyester. 5. Laminated material according to one of claims 1 to 4, characterized in that said layer contains a filler. 6. Laminated material according to claim 5, characterized in that the filler is calcium sulfate, present in an amount of 19 to 25% by weight of polyester. 7. A method of manufacturing the material according to claim 1, characterized in that, at a temperature of 25 to 30 ° C, a first layer of not more than 1 mm of a composition comprising a polyester is sprayed onto a polymethacrylate surface. homopolymer with its catalyst and accelerator, a fibrous reinforcement and / or a filler, and, in addition, polyvinyl acetate in a content such that the shrinkage of the polyester is compensated, then a second layer of 1 to 2 mm from said polyester composition, one rolls to eliminate any air bubble from this layer, one projects successively at time intervals between 15 and 30 min additional layers of said composition, necessary to obtain the desired thickness, each layer being rolled carefully, the operation is terminated by spraying a layer of fiberglass cut not wetted by the polyester and allowed to age for approximately one week at a temperature of approximately 20 ° C. 8. Method according to claim 7, characterized in that the polyester composition contains, by weight, 67 parts of polyester resin, 27 parts of styrene and 6 parts of polyvinyl acetate. 9. Method according to one of claims 7 or 8, characterized in that the polyester contains benzoyl peroxide as catalyst and dimethylaniline as accelerator. 10. Method according to claim 9, characterized in that approximately 1.5% by weight of benzoyl peroxide is used, 1.2% by weight of dimethylaniline, 15 to 25% by weight approximately of calcium sulphate as filler and 0 to 30% approximately by weight of fiberglass 30 to 40 mm in length, relative to the weight of the polyester. 11. Method according to claim 7, characterized in that a mat of 600 g / m2 is projected before the first layer of polyester composition. 12. Method according to claim 7, characterized in that two masts of 450 g / m2 are projected before the first layer of polyester composition. 13. Use of the laminated material according to claim 1 for the manufacture of molded articles.