KR20000075768A - Acrylonitrile/Styrene/Acrylate Copolymers with Improved Stain Resistance - Google Patents

Abstract

The present invention relates to acrylonitrile / styrene / acrylic compositions having advantageous fouling resistance and weather resistance. The composition of the present invention comprises an acrylonitrile-styrene-acrylic elastomer polymer and at least 5% by weight of additives selected from the group consisting of nonionic fluorinated compounds, silicon-based polymers and mixtures thereof.

Description

Acrylonitrile / Styrene / Acrylate Copolymers with Improved Stain Resistance}

The present invention relates to a method for improving the fouling resistance of acrylonitrile-styrene-acrylate (ASA) copolymers and ASA copolymers with improved fouling resistance.

Acrylonitrile / styrene / acrylate (ASA) copolymers are weather resistant UV-resistant thermoplastic polymers that retain color and property stability even upon outdoor exposure. Such copolymers are widely used in automobiles, buildings, and leisure goods. For example, ASA copolymers include body moldings, interior and exterior decorative parts, bumpers, pickup truck caps, and leisure car parts; House exterior walls and decorations, gutters and gutters of roofs, shutters, and window frames; And in the manufacture of pools and pump parts, outdoor furniture, bathtubs, showers, and hot springs. Typically, ASA copolymers are good materials for the manufacture of outdoor articles because they exhibit good weather resistance.

In some cases where ASA copolymers are suitably used, the article formed may be in contact with water, solvents, or other materials that may damage the surface of the article. For example, ASA copolymers are used in the manufacture of automotive grilles, such as automotive front ventilation grilles under windshields. One problem with the front windshield grille is its resistance to water and / or chemicals in windshield cleaning fluids or other products that come into contact with this plastic grille. Products in question include detergents and polishes. Conventional ASA is known to be contaminated in this case.

In addition, contamination of the ASA can be seen in other ASA end-uses exposed to water or mixtures with other drugs. For example, contamination has been found in hot spring baths. Pigments, dyes, and water treatment chemicals are believed to be responsible for the contamination of ASA in these applications.

The term "contamination" as used herein includes surface defects such as discoloration, safflower, loss of gloss, weathering and / or whitening. Typically, such contamination or weathering is caused by exposure to water or a mixture of water and other agents such as chemicals, solvents, pigments and dyes. Contamination can be seen by the appearance of water droplets on the polymer surface. Contamination may occur at any time, but the outdoor or weathered areas have been shown to be more contaminated.

Since many articles that can be made using ASA copolymers are likely to come in contact with water or products containing the above-described drugs, contaminated appearance in weathered areas is very disadvantageous. Therefore, it is highly desirable to produce ASA articles that are stain resistant and free from other appearance problems that may occur in use.

It has been found that ASA copolymers containing certain fluorine- or silicon-based additives have a high degree of stain resistance, stain resistance and weather resistance.

The composition of the present invention comprises an ASA copolymer and a fluorine- or silicon-based additive, or a mixture of such additives in an amount sufficient to improve the stain resistance of the composition. An effective amount is an amount that can represent a measurable or observable difference. The fluorine additive is a fluorinated compound, preferably a fluorinated surfactant. Silicon-based additives are polymeric silicon materials, preferably polysiloxanes. Preferred are hydrophobic, nonionic compounds that can migrate through the ASA matrix to the surface of the formed article.

ASA copolymers of the present invention are known in the art and are described, for example, in US Pat. Nos. 3,944,631, 4,111,876, 4,528,328, 4,537,933, 5,068,285 And 5,070,142. The ASA copolymer comprises a styrene-acrylonitrile copolymer matrix containing at least acrylic rubber particles. The styrene portion may consist of styrene and vinyl aromatic monomers selected from alkyl styrenes such as alpha methyl styrene, p-methyl styrene, ethyl styrene, isopropyl styrene, and the like, and halogenated styrenes such as chlorostyrene, and mixtures thereof. Preferred is a copolymer matrix of acrylonitrile and alpha-methyl styrene. ASA copolymers are typically random amorphous terpolymers prepared by bulk or emulsion copolymerization processes or by grafting of styrene-acrylonitrile to the acrylic elastomer backbone.

The acrylic rubber particles can be grafted to the styrene-acrylonitrile copolymer matrix, which is preferred. During the polymerization, the acrylic rubber particles may be grafted into a polystyrene / acrylonitrile (SAN) matrix by reaction of unsaturated groups in the rubber, or the acrylic rubber particle unsaturated groups may be further reacted with the polymerized SAN matrix to further reduce the SAN after polymerization. Can be grafted into a matrix.

ASA copolymers preferably have an average molecular weight of about 50,000 to about 120,000 as measured against polystyrene standards.

The acrylic rubber particles may be crosslinked at least in part, and such is preferable. In one embodiment of the present invention, the ASA polymer is first emulsion polymerized with an alkyl acrylate or methacrylate or a mixture thereof and at least one crosslinking monomer to form a crosslinking acrylate elastomer, wherein the styrene monomer, acrylonitrile, and acrylate rubber It is prepared by emulsion polymerization of a mixture of By reversing the order of the first two steps, the acrylic elastomer may be polymerized in the presence of a preformed crosslinked styrene-acrylonitrile copolymer.

Typically, in the formation of acrylic rubbers, the acrylate and / or methacrylate monomers are selected from alkyl acrylates and methacrylates having alkyl groups of C ₁ to C ₁₂ , preferably C ₄ to C ₁₀ . Preference is given to C ₄ to C ₈ alkyl acrylates and mixtures of these acrylates with other acrylates or methacrylates. Examples of useful acrylic monomers include ethyl acrylate, isopropyl acrylate, propyl acrylate, n-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 3-methyl-1-butyl acrylate , Isobutyl acrylate, isodecyl acrylate, and corresponding methacrylates. The crosslinking monomers are polyethylene unsaturated monomers, preferably divinyl, diacrylate, triacrylate or tetraacrylate monomers.

The crosslinking monomer of the acrylic polymerization preferably comprises from about 0.05 to about 10% by weight, more preferably from 0.1 to 5% by weight of each monomer mixture. Examples of suitable crosslinking monomers include divinyl benzene, trimethylol triacrylate, allyl methacrylate, diallyl fumarate, diallyl maleate, 1,3-butylene dimethacrylate, diethylene dimethacrylate, ethylene Glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, diethylene glycol diacrylate, divinyl ether, diallyl phthalate, divinyl sorbitol, triethylene glycol dimethacrylate, trimethylene Glycol diacrylate, butylene glycol diacrylate, pentamethylene glycol diacrylate, glyceryl triacrylate, and tetraacrylate esters of pentaerythritol.

Emulsion polymerization can be carried out using conventional methods in the art, for example using anionic, nonionic, or cationic emulsifiers in amounts of about 0.5 to about 5% by weight of the emulsion. Conventional initiators and chain transfer agents can be used, including but not limited to hydrogen peroxide and organic peroxides, and redox catalysts can be used. The initiator may be used in an amount of about 0.005 to about 2 weight percent based on the weight of the monomers.

Polymerization of styrene and acrylonitrile provides a hard matrix component. The preferred weight ratio of acrylonitrile to styrene is about 1: 1 to 3: 7. The acrylonitrile-styrene matrix should have an ASA copolymer in the range of about 20 to about 60 weight percent, preferably about 20 to about 40 weight percent. Preferred are compositions with oc-methyl styrene.

The ASA copolymer is preferably about 5 to about 95 weight percent acrylic elastomer, 0 to about 35 weight percent crosslinked styrene-acrylonitrile copolymer, and about 5 to about 95 weight percent uncrosslinked styrene-acrylonitrile copolymer matrix. It includes. The acrylic rubber particles may comprise thermoplastic polymers such as, for example, bulk copolymerization when the ASA copolymer is prepared.

Suitable ASA copolymer materials are commercially available. Preferred among the commercially available products is LURAN® S 778T, commercially available from BASF Corporation, Mount Olive Continental Drive North 3000, New Jersey, USA 07828.

Preferred fluorine-based additives are hydrophobic fluorinated surfactants. Fluorinated surfactants are characterized by having a hydrophobic residue —C _n F _{2n + 1} and a hydrophilic residue. Fluorinated surfactants are preferably nonionic. Particularly preferred fluorinated surfactants have a carbyl fluoride group of F (CF ₂ CF _x ) _n , where n is 3 to 8.

The hydrophobic fluorinated surfactant may be added to the ASA copolymer composition in an amount of about 0.5% by weight or less, preferably about 0.005 to about 0.15% by weight, particularly preferably about 0.08 to about 0.12% by weight. Fluorinated surfactants are commercially available from, for example, registered trademark of ZONYL® from DuPont Specialty Chemicals, Wellington, Delaware. Especially preferred of these are Zonyl® FSN 100 and FSO 100.

Preferred silicon-based additives are silicone liquid and grease. Among these, polydimethylsiloxane, polyphenylmethylsiloxane, and polydiphenylsiloxane are particularly useful. Especially preferred are polyphenylmethylsiloxanes.

The silicone liquid of the present invention may exhibit a viscosity of about 50 to about 250,000 centistokes. Particular preference is given to using polysiloxanes having a viscosity of about 50,000 to about 150,000 centistokes. Such silicones are commercially available, for example, from Dow Corning Corp., Midland, Michigan, and General Electric, Inc., of Senectadi, NY. Preferred of these is 710 silicone liquid, commercially available from Dow Corning.

The silicone liquid may be added to the ASA copolymer composition in an amount of about 5 wt% or less, preferably about 0.1 to about 3 wt%, particularly preferably about 0.1 to about 1 wt%.

In addition to the ASA copolymer and fluorine- or silicon-based additives, the ASA copolymer composition of the present invention may include additional polymer components or additives. For example, ASA copolymers include polystyrene, polycarbonate, unmodified styrene-acrylonitrile copolymers, polyvinyl chloride, polymethylmethacrylate, and polyesters such as polybutylene terephthalate and polyethylene terephthalate. It can be mixed with one or more different thermoplastic polymers, including but not limited to.

Additional additives that may be included in the ASA copolymer compositions of the invention include hindered amine stabilizers (HALS), benzotriazole UV absorbers, organic and inorganic pigments, dyes, and fillers, heat stabilizers, antioxidants, lubricants, processing aids. And plasticizers such as phenyl carboxylic acid esters of C ₇ to C ₁₁ alcohols such as di-octyl phthalate and di-isononyl phthalate. Preferably, the compositions of the present invention comprise about 0.1 to about 1.0 weight percent HALS or a mixture of HALS.

ASA compositions can be mixed or blended by conventional techniques in the art. For example, the polymer mixture can be prepared by mixing with a single- or twin screw extruder, grinding with a roll mill or Banbury mixer at elevated temperature, continuous melt mixing, or calendering. All such mixtures can be produced, for example, by mixing in a Henschel mixer. Mixing can be performed with the same equipment used to produce the final article, for example a twin screw extruder. Alternatively, this mixture may be prepared into pellets for thermoforming, for example by melt mixing or extrusion molding techniques. Compounding and pelletizing can be carried out by any of a variety of techniques known in the art.

The compositions of the present invention can be processed by any thermoforming technique, such as injection molding, compression molding, and extrusion molding techniques. Molding conditions may be the same as those conventionally used for ASA copolymer compositions. Molding conditions for specific compounds and devices can be optimized by one step testing according to conventional methods.

The compositions of the present invention can advantageously be used to make automotive parts, such as automotive front ventilation grilles and the like, as well as building parts, outdoor items and articles exposed to water, such as bathtubs, showers, and hot springs.

The following examples illustrate the invention. The examples are illustrative only and do not in any way limit the scope of the invention described and claimed. All parts are by weight unless otherwise indicated.

<Example 1>

The invention was tested according to Ford Motor Company Test Method No. 84-52509. Luran® S 778T, an ASA commercially available from BASF Corporation, was used as the ASA with a standard UV stabilizer package. The same material without the standard UV stabilizer package was used as ASA without UV stabilizer. All samples contained carbon black according to BASF Corporation's Color Code BLK-31261. It was added to the identified ASA while varying the amount of fluorine surfactant or silicone containing additive of the present invention. The components of the composition were mixed with a Henschel type mixer and then blended with a 40 mm twin screw extruder.

Sample plaques were prepared from samples using standard injection molding techniques. After stirring for the usual 24 hours, plaques were placed in a Xenon Arc Weatherometer for every SAE J1960 procedure. After 2500 kJ / m 2, the following contamination test was performed.

Composition ASA with UV Package ASA without UV package additive amount A X -0- -0- B X -0- -0- C X DuPont Zonyl® FSO 100 0.1 D X DuPont Zonyl® FSO 100 0.1 E X DuPont Zonyl® FSO 100 0.1 F ¹ X DuPont Zonyl® FSO 100 0.1 G X DuPont Zonyl® FSO 100 0.1 H X FSO 100 0.1 I X -0- -0- J X ² FSO 100 0.1 K X Dow Corning Silicone 710 Fluid 0.5 L X FSN 100 0.1 1 = carbon black introduced in masterbatch rather than 1/22 = injection in standard UV package

Inspection while there are dots on the test panel

Using a pipette, drops each of the windshield cleaning liquid commercially available from Ford Motor Company, the windshield cleaning liquid containing rubber tubing extract, and the windshield cleaning liquid containing nylon tubing extract were added dropwise onto the prepared sample panel. It was. The shape of the pipette wash point was observed after 3 minutes.

Sample The appearance of the points on the panel A Not smeared B Not smeared C Almost uniform D Smear and bind to each other; Oil appearance (rainbow color) E Smeared and combined with each other (rainbow color) F Smeared and joined together (slightly rainbow colored) G Homogeneous and hardly smeared in contrast B (no rainbow color) H Smeared in the middle (slightly rainbow colored) I Significantly maintains bungee or annulus (rainbow color) J Markedly smeared (rainbow color) K Keeps shape without smearing L Significant smearing at high temperatures (rainbow color)

After removing the stain and washing with hot water for 15 seconds, after drying, observe the appearance of the panel

After completing the observations shown in Table 1 above, the panels were washed with warm water and dried with compressed nitrogen. Then, surface contamination and dirt were observed.

Sample External appearance of the panel surface Rating Scale (0 = Best; 10 = Best) A stain 0,0 B stain 0,0 C Some blots 3,2 D Some blots 5,4 E Some blots 7,5 F Some blots 7,5 G stain 2,2 H Some blots 6,6 I Zero point 10,10 J Zero point 10,9 K stain 8,8 L Muo point (high temperature) 10,9

Grading scale: 0 indicates significant white residue; 10 indicates that no residue was observed.

The composition of the present invention provides an advantage against staining and stain resistance.

The present invention has been described in detail with reference to the above preferred embodiments. However, it will be understood that such variations and modifications may be made within the spirit and scope of the invention and the following claims.

Claims (10)

A composition comprising an acrylonitrile-styrene-acrylic elastomer polymer and at least 5 wt% or less of an additive selected from the group consisting of nonionic fluorinated compounds, silicon-based polymers and mixtures thereof. The composition of claim 1 wherein said additive is selected from the group consisting of fluorinated surfactants, polydimethylsiloxanes, polymethylphenylsiloxanes, polydiphenylsiloxanes, and mixtures thereof. The composition of claim 1 wherein said additive is a fluorinated surfactant. The composition of claim 3, wherein the fluorinated surfactant comprises from about 0.005 to about 0.5 weight percent of the composition. 4. The composition of claim 3 wherein the fluorinated surfactant is an ethoxylate fluorocarbon having a carbyl fluoride structure of F (CF ₂ CF ₂ ) _n where n is 3 to 8. The composition of claim 1 wherein said additive is polysiloxane. The composition of claim 6, wherein said polysiloxane comprises from about 0.1 to about 5 weight percent of the composition. The composition of claim 1 further comprising a thermoplastic polycarbonate and mixtures thereof. A vehicle front ventilation grille made of the composition according to claim 1. A) forming an acrylonitrile-styrene-acrylic elastomer copolymer, B) mixing acrylonitrile-styrene-acrylic elastomer copolymer with at least one additive selected from the group consisting of fluorinated compounds, silicon-based polymers and mixtures thereof A method for improving fouling resistance of acrylonitrile-styrene-acrylic elastomer copolymer composition comprising a.