WO2007134988A1

WO2007134988A1 - Use of silane-functional polyvinyl esters as a low-profile additive

Info

Publication number: WO2007134988A1
Application number: PCT/EP2007/054573
Authority: WO
Inventors: Thomas Lehmann; Klaus-Jürgen EDER
Original assignee: Wacker Polymer Systems Gmbh & Co. Kg
Priority date: 2006-05-24
Filing date: 2007-05-11
Publication date: 2007-11-29

Abstract

The invention provides for the use of silane-functional solid polyvinyl ester resins as a low-profile additive in unsaturated polyester resin compositions, characterized in that the solid polyvinyl ester resin contains 0.1 to 15% by weight, based on the total weight of the polymer, of silane-functional monomer units.

Description

Use of silane-functional polyvinyl esters as low-profile additive

The invention relates to the use of silane-functional polyvinyl esters as a low-profile additive.

Unsaturated polyester resin compositions (UP resins) are frequently used in the production of sheet-like plastic parts. These polyester resins are reaction products of a dicarboxylic acid or a dicarboxylic acid anhydride with a polyol. Such polyester resin compositions also contain a monomer having ethylenically unsaturated groups, generally styrene. Styrene is added to the polyester resin composition to dissolve the polyester and to ensure that the polyester composition is a flowable mass. To reinforce the plastic parts obtained with the polyester resin composition, the polyester resin compositions still contain fiber materials such as glass fiber, carbon fiber or corresponding fiber mats.

The problem with the processing of such polyester resin compositions (Reinforced Plastic Composites = FPR composites) is the volume shrinkage during the heat curing of the polyester resin. To reduce the shrinkage in the curing of the polyester resin therefore so-called low-profile additives are added. The low-profile additive reduces shrinkage during curing, reduces residual stresses, reduces micro-cracking and facilitates compliance with manufacturing tolerances. The low-profile additives are thermoplastics such as polystyrene, polymethyl methacrylate and in particular polyvinyl acetate, which frequently also contain carboxyl-functional comonomer units.

When using low-profile additives, a good solubility in styrene, a low starting viscosity of the styrenic solution and a fast thickening effect with a stable final level are desired. Conventional low-profile additives, for example based on polyvinyl acetates with carboxyl Functional comonomer units (DE-OS 27 48 843), can not fully satisfy the initial viscosity and thickening effect. To improve these properties, it is proposed in WO 2006002833 A to use solid polyvinyl acetate resins which, in addition to carboxyl-functional comonomer units, also contain terminal carboxyl groups. The problem is that the previously known low-profile additives only develop a Schwundmaß reducing effect with relatively high molecular weight. Due to the higher viscosity due to the molecular weight in styrenic solution but less cheaper filler can then be processed in the FRP composites.

Against this background, the object was to provide solid polyvinyl ester resins which, with the lowest possible viscosity in styrenic solution, lead to an effective reduction in shrinkage.

The invention relates to the use of silane-functional polyvinyl ester solid resins as low-profile additive in unsaturated polyester resin compositions, characterized in that the polyvinyl ester solid resin 0.1 to 15 wt .-%, based on the total weight of the polymer, on silane functional monomer units.

Suitable vinyl ester monomers for the polyvinyl ester solid resin are vinyl esters of unbranched or branched carboxylic acids having 1 to 18 carbon atoms. Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, vinyl pivalate and vinyl esters of CC-branched monocarboxylic acids having 5 to 13 C atoms, for example VeoVa9 ^R or VeoValOR (trade name of the company Shell) or mixtures said vinyl ester monomer. Particularly preferred is vinyl acetate.

Monomers which are suitable for introducing the silane-functional monomer units are preferably ethylenically unsaturated silicon compounds of the general formula R ¹ SiR ² O-2 (OR ³ ) 1-3, where R ^{1 is} CH ₂ = CR ⁴ - (CH ₂ ) oi or CH ₂ = CR ⁴ CO ₂ (CH ₂ ) i_ ₃ , R ^{2 is} C 1 to C ₃ alkyl, C _x to C 3 alkoxy or Halogen, preferably Cl or Br, R ^{3 is} an unbranched or branched, optionally substituted alkyl radical having 1 to 12 C-atoms, preferably 1 to 3 C-atoms, or is an acyl radical having 2 to 12 C-atoms, wherein R ^{3 may} optionally be interrupted by an ether group, and R ^{4 is} H or CH ₃ .

Preferred ethylenically unsaturated, silane-containing monomers are γ-acrylic or γ-methacryloxypropyltri (alkoxy) silanes and α-methacryloxymethyltri (alkoxy) silanes, γ-methacryloxypropylmethyldi (alkoxy) silanes; Vinylsilanes such as Vinylalkyldi (alkoxy) silanes and vinyltri (alkoxy) silanes, where as alkoxy groups, for example, methoxy, ethoxy, methoxyethylene, Ethoxyethy- len, Methoxypropylenglykolether- or Ethoxypropylenglykol- ether radicals can be used. Examples of preferred silane-containing monomers are 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltris (1-methoxy) isopropoxysilane, vinyltri butoxysilane, vinyltriacetoxysilane, methacryloxymethyltrimethane oxysilane, 3-methacryloxypropyltris (2-methoxyethoxy) silane, vinyltrichlorosilane, vinylmethyldichlorosilane, vinyltris (2-methoxyethoxy) silane, trisacetoxyvinylsilane, allylvinyltrimethoxysilane, allyltriacetoxysilane, vinyldimethylmethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane , Vinylisobutyldimethoxysilane, vinyltriisopropyloxysilane, vinyltributoxysilane, vinyltrihexyloxysilane, vinylmethoxydihexoxysilane, vinyltrioctyloxysilane, vinyldimethoxy-octyloxysilane, vinylmethoxydioctyloxysilane, vinylmethoxydilauryloxysilane, vinyldimethoxylauryloxysilane s as well as polyethylene glycol-modified vinylsilanes.

As silanes it is particularly preferable to use vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltris (1-methoxy) isopropoxysilane, methane acryloxypropyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane and methacryloxymethyltrimethoxysilane and mixtures thereof.

Particularly preferred solid polyvinyl ester resins having silane-functional monomer units are those based on vinyl acetate and of silane-containing monomers from the group comprising γ-acrylic or γ-methacryloxypropyltri (alkoxy) silanes, OC-methacryloxymethyltri (alkoxy) silanes, γ- Methacryloxypropylmethyldi (alkoxy) silanes, vinylalkyldi (alkoxy) silanes and vinyltri (alkoxy) silanes, in each case with alkyl or alkoxy radicals having 1 to 3 C atoms. The proportion of silane-functional monomer units is preferably 0.3 to 10% by weight, particularly preferably 0.5 to 5% by weight, in each case based on the total weight of the polyvinyl ester solid resin. The weight-average molecular weight M w of the solid polyvinyl ester resins having silane-functional monomer units is preferably from 5000 to 50 000 g / mol, more preferably from 5000 to 20 000 g / mol (determination by SEC).

The silane-functional polyvinyl ester solid resins are prepared by the bulk, suspension or, preferably, solution polymerization process. Suitable solvents are, for example, monohydric, aliphatic alcohols having 1 to 6 C atoms, preferably methanol, ethanol, propanol, isopropanol. Particularly preferred are ethanol and isopropanol. The reaction is generally carried out under reflux conditions, generally at a polymerization temperature of 40 ⁰ C to 140 ⁰ C, to use the Siedekuhlung to dissipate the heat of reaction. This can be done at atmospheric pressure as well as under slight overpressure.

The initiators used are organic peroxides or azo compounds. Suitable examples include diacyl peroxides such as dilauroyl peroxide, peroxo esters such as t-butyl peroxypivalate or t-butyl peroxo-2-ethylhexanoate, or peroxodicarbonates such as diethyl peroxodicarbonate. The amount of initiator is generally NEN from 0.01 to 5.0 wt .-%, based on the monomers. The initiators can both be submitted and metered. It has proven useful to submit a portion of the required amount of initiator and to meter the rest continuously during the reaction.

The adjustment of the molecular weight can be carried out in a manner known to the skilled worker by polymerization in the presence of molecular weight regulators. Suitable regulators are, for example, alcohols such as ethanol or isopropanol, aldehydes such as acetaldehyde or propionaldehyde, silane-containing regulators such as mercaptosilanes, for example 3-mercaptopropyltrimethoxysilane.

The polymers can be prepared by a batch process, all components of the polymerization mixture being initially charged in the reactor, or by a seim batch process, in which one or more components are initially introduced and the remainder is metered in, or a continuous polymerization is carried out be added, wherein the components are added during the polymerization. The dosages may optionally be carried out separately (spatially and temporally).

For use as a low-profile additive, the silane-functional polyvinyl ester is generally dissolved in styrene and optionally applied with further additives, such as fillers, thickeners, initiators and processing aids. The silane-functional polyvinyl esters are suitable as low-profile additives for all common production processes of FRP composites, such as Sheet Molding Compound Technology (SMC), Bulk Molding Compound Technology (BMC), Resin Transfer Molding (RTM), Resin Injection Molding (RIM). The composition of the formulations and the amounts used of the low-profile additives depend on the manufacturing process chosen and are known to the person skilled in the art. In general, the silane-functional

Polyvinyl ester in a 10 to 40 wt .-% - solution in styrene applied. The amount used is generally 10 to 50 wt .-%, based on the total formulation. The following examples serve to further illustrate the invention:

There were the following solid resins as low. Profile Additives (LPA) tested:

Comparative Example 1 (LPAl):

Polyvinyl acetate homopolymer with Mw = 15,000 g / mol

Example 2 (LPA2):

Vinyl acetate-vinyltriethoxysilane copolymer with 2% by weight of vinyltriethoxysilane and with Mw = 15,000 g / mol

Comparative Example 3 (LPA3):

Polyvinyl acetate homopolymer with Mw = 30,000 g / mol

Example 4 (LPA4):

Vinyl acetate-vinyltriethoxysilane copolymer with 2% by weight of vinyltriethoxysilane and with Mw = 30,000 g / mol

Comparative Example 5 (LPA5):

Vinyl acetate-crotonic acid copolymer with 1 wt .-% crotonic acid and with Mw = 170,000 g / mol.

The LPAs were tested in the following recipe:

Polyester resin (Palapreg P 1803) 15.9 parts by weight

LPAX (40% solution in styrene) 7.9 parts by weight styrene (200 ppm benzoquinone) 2.6 parts by weight

Calcium carbonate filler 53.6 parts by weight

Zinc stearate 3.0 parts by weight

T-butyl perbenzoate 1.0 parts by weight

From the raw materials listed in the table, a paste was kneaded. Shortly before processing, 0.5 parts by weight of Luvatol MK 35, a thickener, was stirred in. Thereafter, with the paste and with 20 parts by weight of glass fiber was a hand laminate created and processed into an SMC. The product was stored for 3 days at 20 ^° C. and 50% room humidity. Thereafter, it was pressed at 160 ° C in a common SMC press to form a component. The shrinkage was determined after cooling the press and determines the volume change in percent.

The information on the viscosity refers in each case to the viscosity of the solution in styrene.

The following results were obtained:

The comparison of V.bsp. 1 with Ex. 2 and the comparison of V.bsp. 3 with Ex. 4 shows that with the silane-modified polyvinyl ester solid resins with the same molecular weight, a significantly better reduction of the shrinkage is obtained. It can therefore be incorporated in the inventive use higher levels of fillers in the recipe. The comparison of Example 4 with Ex. 2 and with V.bsp. Figure 5 shows that at significantly lower molecular weight with Ex. 2, shrinkage is reduced to a similar extent as with the much higher molecular weight solid resins.

Claims

Claims:

1. Use of silane-functional polyvinyl ester solid resins as a low-profile additive in unsaturated polyester resin compositions, characterized in that the

Polyvinyl ester solid resin 0.1 to 15 wt .-%, based on the total weight of the polymer, of silane-functional monomer units.

2. Use according to claim 1, characterized in that a silane-functional polyvinyl acetate solid resin is used.

3. Use according to claim 1 or 2, characterized in that derive the silane-functional monomer units of ethylenically unsaturated silicon compounds, with the general formula R ¹ SiR ² o-2 (OR ³ ) 1-3, wherein R ^{1 is} the Be ^¬ interpretation CH ₂ = CR ⁴ - (CH ₂₎ 0-1 or CH ₂ = CR ⁴ CO ₂ (CH ₂₎ i_ ₃ has R ² to C3 alkyl group, C _{x have} the meaning Ci - to C3-alkoxy radical or halogen, has R ^{3 is} an unbranched or branched, optionally substituted alkyl radical having 1 to 12 C atoms or an acyl radical having 2 to 12 C atoms, where R ^{3 may} optionally be interrupted by an ether group, and R ^{4 is} H or CH ₃ .

4. Use according to claim 1 to 3, characterized in that as silane-functional polyvinyl ester solid resins such on the basis of vinyl acetate and silane-containing monomers from the group containing γ-acrylic or γ-methacrylic oxypropyltri (alkoxy) silanes, CC Methacryloxymethyltri (alk- oxy) silanes, γ-methacryloxypropyl-methyldi (alkoxy) silanes, vinylalkyldi (alkoxy) silanes and vinyltri (alkoxy) silanes, each with alkyl or alkoxy having 1 to 3 carbon atoms, are used.

5. Use according to claim 1 to 4, characterized in that the silane-functional polyvinyl ester solid resins 0.5 to 5 wt .-%, each based on the total weight of Polyvinyl ester solid resin containing silane-functional monomer units.

6. Use according to claim 1 to 5, characterized in that the weight-average molecular weight Mw of the silane-functional polyvinyl ester solid resins from 5000 to 20,000 g / mol.

7. Use according to claim 1 to 6, characterized in that the silane-functional polyvinyl ester solid resins as

Low profile additive used in FRP composites manufacturing processes as per sheet molding compound technology (SMC), bulk molding compound technology (BMC), resin transfer molding (RTM), resin injection molding (RIM).