KR100762740B1 - Silicone Impact Modifier Having High Refractive Index and Good Thermal Stability and Method for Preparing the Same - Google Patents

Abstract

The present invention relates to a rubber particle prepared by (A) swelling a styrenic aromatic compound and an alkyl acrylate in the presence of organosiloxane crosslinked (co) polymer particles and then crosslinking polymerization; And (B) a plastic shell formed by graft copolymerization of a vinyl monomer and an unsaturated dicarboxylic acid on the rubber particles, and a high refractive index silicone impact modifier having excellent thermal stability, and a method of manufacturing the same.

Silicone, impact modifier, organosiloxane, unsaturated dicarboxylic acid, refractive index, thermal stability

Description

Silicon Impact Modifier Having High Refractive Index and Good Thermal Stability and Method for Preparing the Same}

Field of invention

The present invention relates to a silicone-based impact modifier and a method of manufacturing the same. More specifically, the present invention relates to a silicone-based impact modifier excellent in thermal stability and excellent appearance when applied to a thermoplastic resin and a method of manufacturing the same.

Background of the Invention

In general, the impact modifier is added a lot to compensate for the impact resistance of the thermoplastic resins having a low impact resistance. The impact modifier is generally a core-shell type structure composed of a shell of a thermoplastic resin component to improve compatibility of the rubber core particles with the thermoplastic resin. In general, as the core-shell type impact modifier, many impact modifiers having a rubber component of butadiene-based material as a core material are used. However, butadiene-based impact modifiers have a disadvantage in that carbon-carbon double bonds present in rubber components are easily decomposed by high heat treatment conditions, ultraviolet rays, chemicals, etc., and thus have very poor thermal stability, weather resistance, and chemical resistance.

On the other hand, impact modifiers containing acrylate rubber as a core material show high thermal stability and weather resistance due to the absence of carbon-carbon double bonds, but the impact reinforcing effect at low temperatures is low due to the high glass transition temperature. Have

However, the impact modifier having a silicone-based rubber component as a core material does not have a carbon-carbon double bond, and the glass transition temperature is also very low, thereby exhibiting excellent thermal stability, weather resistance, and impact strengthening effect at low temperatures. U.S. Patent Nos. 4,994,522 and 5,132,359 disclose silicone-based impact modifiers as impact modifiers for vinyl chloride-based resins, and Japanese Patent Laid-Open No. 194-116470 describes impact modifiers employing silicone-based polymers having a particle diameter of 100 nm or less, and Japanese Patent Publication 2004-331726 discloses an impact modifier using a silicone polymer having a particle size distribution of 300 to 2000 nm. As the shell constituent of the silicone impact modifier, a methyl methacrylate polymer or a polystyrene-acrylonitrile copolymer is used. These shell components have a problem of decomposing under high temperature processing conditions, which may cause deterioration of physical properties or appearance defects when applied to thermoplastic resins requiring high temperature processing conditions.

Accordingly, the present inventors cross-polymerize styrene-based aromatic compounds and alkyl acrylates in the presence of organosiloxane cross-linked (co) polymer particles to produce rubber particles, and then by graft copolymerization of vinyl monomers and unsaturated dicarboxylic acids, refractive index It is 1.490 ~ 1.590, and it is the development of silicone-based impact modifier that shows excellent thermal stability and appearance when applied to thermoplastic resin.

An object of the present invention is to provide a silicone-based impact modifier and its production, which can be applied to high temperature processing conditions and exhibit excellent appearance characteristics when applied to thermoplastic resins by providing high refractive index, thermal stability, and compatibility while maintaining the existing physical properties of the silicone-based impact modifier It is to provide a method.

Both the above and other objects of the present invention can be achieved by the present invention described below.

Summary of the Invention

The high refractive index impact modifier of the present invention having excellent thermal stability may include (A) rubber particles prepared by cross-polymerizing styrene-based aromatic compounds and alkyl acrylates in the presence of organosiloxane cross-linked (co) polymer particles; And (B) a plastic shell formed by graft copolymerization of a vinyl monomer and an unsaturated dicarboxylic acid on the rubber particles.

Detailed Description of the Invention

(A) Preparation of Rubber Particles

The rubber particles of the present invention are prepared by polymerizing styrene-based aromatic compounds and alkyl acrylates in the presence of organosiloxane crosslinked (co) polymer particles. The organosiloxane crosslinked (co) polymer has a refractive index of 1.410-1.500. If using an organosiloxane crosslinker having a refractive index of less than 1.410, the refractive index of the impact modifier cannot achieve a level of 1.490 or more, and when using an organosiloxane copolymer having a refractive index of more than 1.500, the glass transition of the organosiloxane polymer. The temperature rises and the compatibility with various organic solvents increases, causing serious degradation of various physical properties. Accordingly, the refractive index is preferably 1.410 to 1.500, and in consideration of various physical property balances, the refractive index is more preferably 1.410 to 1.450.

The organosiloxane crosslinked (co) polymer of the present invention is a crosslinked organosiloxane, and specifically crosslinked dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane and the like can be used. Preference is given to using forms in which two or more organosiloxanes are copolymerized.

In the present invention, the organosiloxane crosslinked (co) polymer is preferably used in an amount of 5 to 90 parts by weight, more preferably 10 to 50 parts by weight, based on the total weight of the reactants.

The organosiloxane crosslinked (co) polymer is a silicone latex which is stably dispersed in ion exchanged water using an emulsifier. As the emulsifier, anionic emulsifiers such as sodium, ammonium, or potassium salt of alkyl sulfate having 4 to 30 carbon atoms may be used, and specifically, sodium dodecyl sulfate or sodium dodecylbenzene sulfate may be used. It is preferable to use sodium dodecylbenzene sulfate which can be used at a wide range of pH. In the present invention, it is preferable to use 0.1 to 5 parts by weight, more preferably 0.1 to 2 parts by weight based on the total weight of the emulsifier.

A single liquid or a mixture of styrene-based aromatic compound monomers, alkyl acrylate monomers, crosslinking agents and the like is added to the silicone latex under a nitrogen stream, and the temperature is raised to 50 to 100 ° C. to swell the organosiloxane crosslinked (co) polymer. Thereafter, a polymerization initiator is added, and polymerization is performed at 50 to 100 ° C. If necessary, the swelling-copolymerization of the monomer mixture may be performed or the swelling-polymerization of each monomer may be performed in stages. Preferably, the styrene-based aromatic compound is first swelled-polymerized, and then the alkylacrylate monomer and the crosslinking agent are Then swell-polymerize.

The styrene-based aromatic compound may be used styrene, alpha methyl styrene, divinyl benzene and vinyl toluene, and preferably styrene. The styrene-based aromatic compound is used in 0.01 to 50 parts by weight.

As the alkyl acrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, or the like may be used, and preferably n-butyl acrylate having a low glass transition temperature is used. The alkyl acrylate is used in 5 to 90 parts by weight.

As the crosslinking agent, allyl methacrylate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene and the like can be used. Preferably allyl methacrylate or triallyl isocyanurate is used. More preferably, triallyl isocyanurate excellent in thermal stability is used. In the present invention, the crosslinking agent is used in an amount of 0.01 to 10 parts by weight based on the total weight of the reactants, and preferably 0.01 to 5 parts by weight.

The polymerization initiator uses free group initiators which are initiators that generate free groups by pyrolysis or oxidation-reduction reactions. Specifically, potassium persulfate, magnesium persulfate, benzoyl peroxide, hydrogen peroxide, dibenzyl peroxide, cumene hydroperoxide and tert -butyl hydroperoxide may be used. The polymerization initiator is used in an amount of 0.1 to 5 parts by weight based on the total weight of the reactants, and preferably 0.1 to 2 parts by weight.

The weight ratio of the organosiloxane crosslinked (co) polymer and the alkylacrylate crosslinked polymer is preferably 1: 6 to 6: 1. When the ratio of the organosiloxane crosslinked (co) polymer and the alkyl acrylate crosspolymer is less than 1: 6, the impact reinforcing effect at low temperature due to the organosiloxane crosslinked (co) polymer is significantly reduced, and when the ratio exceeds 6: 1. The decrease of resin compatibility by excess organosiloxane cross-linked (co) polymers decreases the impact reinforcing effect and increases the production cost.

The weight ratio of the styrene-based aromatic compound and the alkyl acrylate is preferably 1:20 to 1: 1. When the weight ratio of the styrene-based aromatic compound and the alkyl acrylate is less than 1:20, the refractive index and the colorability are remarkably decreased, and when the weight ratio is greater than 1: 1, the impact resistance is significantly reduced.

(B) plastic shell

Following the synthesis of the rubber particles, a graft copolymerization of a vinyl monomer and an unsaturated dicarboxylic acid is performed to prepare a plastic shell. Graft copolymerization is carried out by adding a polymerization initiator to the rubber particle latex produced in the rubber particle production process, and a mixture of vinyl monomer and unsaturated dicarboxylic acid at a constant rate at a reaction temperature of 50 ~ 100 ℃. The unsaturated dicarboxylic acid may improve thermal stability and improve dispersibility in the thermoplastic resin.

Alkyl methacrylate, acrylate and ethylenically unsaturated aromatic compounds may be used as the vinyl monomer, and preferably, a single substance or a mixture of two or more such as methyl methacrylate, styrene and acrylonitrile is used. It is more preferable to use styrenic aromatic compounds in order to maximize refractive index and colorability and to impart good appearance characteristics. In the present invention, the vinyl monomer is used in an amount of 5 to 90 parts by weight, preferably 10 to 50 parts by weight, based on the total weight of the reactants.

As the unsaturated dicarboxylic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid and respective anhydrides may be used. Preferably, maleic acid and maleic anhydride are used. When maleic anhydride is used, the copolymerization with the styrene-based aromatic compound proceeds smoothly, and the dispersibility of the prepared impact modifier is improved in the thermoplastic resin. It is preferable to use the unsaturated dicarboxylic acid of this invention at 0.1-10 weight part.

It is preferable that the weight ratio of the said vinylic monomer and unsaturated dicarboxylic acid is 80:20-99.5: 0.5.

In addition, the weight ratio of the rubber particles (A) and the plastic shell (B) is preferably 5: 5 to 9: 1. If the ratio of the plastic shell (B) to the rubber particles (A) is less than 5: 5, the impact reinforcing effect is remarkably decreased due to the lack of rubber content. Along with the reduction of the effect, the production cost becomes too high.

Thereafter, the flocculant is recovered by flocculation, filtration and drying of the silicone-based impact modifier. As the flocculant, metal salts are used a lot, and specifically, magnesium chloride, calcium chloride, magnesium sulfate and calcium sulfate may be used.

The impact modifier of the present invention has a refractive index in the range of 1.490 to 1.590, preferably in the range of 1.500 to 1.570. If the refractive index of the impact modifier is less than 1.490, as in the conventional silicone-based impact modifier, when applied to a polycarbonate resin having a refractive index of 1.570 to 1.590, the difference in refractive index is severely degraded. In addition, by adding unsaturated dicarboxylic acid than in the case of forming a shell with only a polymer of vinyl monomers, thermal stability is improved and dispersibility in a thermoplastic resin is improved, thereby minimizing physical property degradation during processing and improving appearance characteristics.

The thermoplastic resin that can be applied to the impact modifier of the present invention is not particularly limited, and applied to vinyl chloride resin, styrene resin, styrene-acrylonitrile resin, acrylic resin, ester resin, ABS resin, polycarbonate resin, and the like. Possible, the effect is maximized when applied to the polycarbonate resin used as the exterior material of the electronic device. In particular, when the silicone impact modifier of the present invention is applied to a polycarbonate resin, it is preferable to include 0.5 to 30 parts by weight of the silicone impact modifier with respect to 100 parts by weight of the polycarbonate resin.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Preparation of Rubber Particle A

A silicone latex and 36 g of styrene having a refractive index of 1.429, a particle size of 220 nm, and 90% of a dimethylsiloxane-diphenylsiloxane crosslinked copolymer having a toluene insoluble content of 65% and 3.4 g of sodium dodecylbenzene sulfate in 970 g of ion-exchanged water are room temperature. After mixing at, the temperature of the liquid mixture was raised to 75 ° C. A solution in which 0.9 g of potassium persulfate was dissolved in 22.5 g of ion-exchanged water was added thereto, and the temperature was maintained at 75 ° C. for 2 hours. After cooling the reaction solution to room temperature, 190 g of n-butyl acrylate and 9 g of triallyl isocyanurate were mixed at room temperature. After raising the temperature of the mixed solution back to 75 ° C., a solution in which 0.9 g of potassium persulfate was dissolved in 22.5 g of ion-exchanged water was added and maintained at 75 ° C. for 2 hours to prepare rubber particle latex A. Reaction conversion was 98.5%.

Preparation of Rubber Particle B

Silicon latex and styrene 18.5g, in which 74 g of dimethylsiloxane-diphenylsiloxane cross-linked copolymer having a refractive index of 1.428, particle size of 175 nm and 63% of toluene insoluble content and 1.7 g of sodium dodecylbenzene sulfate were dispersed in 1060 g of ion-exchanged water, After mixing 49.95 g of n-butyl acrylate at room temperature, the temperature of the liquid mixture was raised to 75 degreeC. A solution of 0.2 g of potassium persulfate dissolved in 4.4 g of ion-exchanged water was added three times every 30 minutes and maintained at 75 ° C. for 1.5 hours.

After the reaction solution was cooled to 60 ° C., 117 g of n-butyl acrylate and 1.85 g of triallyl isocyanurate were mixed. After raising the temperature of the mixed solution back to 75 ° C., a solution in which 0.74 g of potassium persulfate was dissolved in 17.76 g of ion-exchanged water was added and maintained at 75 ° C. for 2 hours to prepare rubber particle latex B. Reaction conversion was 96.5%.

Example 1

A solution in which 0.7 g of potassium persulfate was dissolved in 22.5 g of ion-exchanged water was added while maintaining the rubber particle latex A at 75 ° C., and then a mixed solution of 133.65 g of styrene and 1.35 g of maleic anhydride was added dropwise for 15 minutes. After maintaining at 75 ℃ for 4 hours and then cooled to room temperature. Final reaction conversion was 95.8%.

1.5% MgSO ₄ aqueous solution and the final reaction solution were mixed at 75 ° C., washed with water, and dried to obtain impact modifier powder.

Example 2

A solution in which 0.74 g of potassium persulfate was dissolved in 17.76 g of ion-exchanged water was added while maintaining the rubber particle latex B at 75 ° C., and then a mixed solution of 110 g of styrene and 1 g of maleic anhydride was added dropwise for 30 minutes. After maintaining for 2 hours at 75 ℃ was cooled to room temperature. Final reaction conversion was 93.6%.

The 1% MgSO ₄ aqueous solution and the final reaction solution were mixed at 75 ° C., washed with water, and dried to obtain impact modifier powder.

Example 3

A solution in which 0.74 g of potassium persulfate was dissolved in 17.76 g of ion-exchanged water was added while maintaining the rubber particle latex B at 75 ° C., and then a mixture of 108 g of styrene and 3 g of maleic anhydride was added dropwise for 30 minutes. After maintaining for 2 hours at 75 ℃ was cooled to room temperature. Final reaction conversion was 93.4%.

The 1% MgSO ₄ aqueous solution and the final reaction solution were mixed at 75 ° C., washed with water, and dried to obtain impact modifier powder.

Example 4

A solution in which 0.74 g of potassium persulfate was dissolved in 17.76 g of ion-exchanged water was added while maintaining the rubber particle latex B at 75 ° C. Then, a mixed solution of 99 g of styrene and 11 g of maleic anhydride was added dropwise for 30 minutes. After maintaining for 2 hours at 75 ℃ was cooled to room temperature. Final reaction conversion was 91.5%.

The 1% MgSO ₄ aqueous solution and the final reaction solution were mixed at 75 ° C., washed with water, and dried to obtain impact modifier powder.

Comparative Example 1

The rubber particle latex A was maintained at 75 ° C, and a solution in which 0.7 g of potassium persulfate was dissolved in 22.5 g of ion-exchanged water was added thereto, followed by dropwise addition of 135 g of styrene for 15 minutes. After maintaining at 75 ℃ for 4 hours and then cooled to room temperature. Final reaction conversion was 96.8%.

1.5% MgSO ₄ aqueous solution and the final reaction solution were mixed at 75 ° C., washed with water, and dried to obtain impact modifier powder.

Comparative Example 2

The rubber particle latex A was maintained at 75 ° C, and a solution in which 0.7 g of potassium persulfate was dissolved in 22.5 g of ion-exchanged water was added thereto, followed by dropwise addition of a mixture of 101.25 g of styrene and 33.75 g of acrylonitrile for 15 minutes. After maintaining at 75 ℃ for 4 hours and then cooled to room temperature. Final reaction conversion was 96.3%.

1.5% MgSO ₄ aqueous solution and the final reaction solution were mixed at 75 ° C., washed with water, and dried to obtain impact modifier powder.

Comparative Example 3

A solution in which 0.74 g of potassium persulfate was dissolved in 17.76 g of ion-exchanged water was added while maintaining the rubber particle latex B at 75 ° C., and then 111 g of styrene was added dropwise for 30 minutes. After maintaining for 2 hours at 75 ℃ was cooled to room temperature. Final reaction conversion was 93.7%.

The 1% MgSO ₄ aqueous solution and the final reaction solution were mixed at 75 ° C., washed with water, and dried to obtain impact modifier powder.

Silicon-based impact modifier particles obtained through the above process were evaluated for physical properties through the following method.

(1) Refractive index: The test piece (thickness = 1 mm) was obtained using the hot press. The refractive index of the specimen was measured using a prism coupler laser refractometer (Sairon Tech., SPA-4000) using a light source having a wavelength of 632.8 nm.

(2) Thermal stability: After the impact modifier particles were heat-treated in a nitrogen atmosphere for 30 minutes at a temperature of 320 ℃ and the weight loss rate was measured.

(3) Injection stability: The degree of discoloration generated in the process of injecting flat specimen under the condition of molding temperature of 320 ℃ in a 10 oz injection machine using a pellet prepared by mixing polycarbonate, impact modifier and dye at 97: 3: 0.2 ΔE _ab was measured using a color difference meter.

(4) Appearance evaluation: Visually judged.

(5) Impact resistance: The polycarbonate and the impact modifier were mixed at a ratio of 97: 3 to produce pellets using a twin screw extruder having a diameter of 45 mm. The prepared pellets were dried at 110 ° C. for 3 hours or more, and then injected in a 10 oz injection machine under molding conditions of 260 to 330 ° C. and mold temperatures of 60 to 100 ° C. to produce 1/4 ”specimens, and the impact strength of ASTM D-256 was measured. Measured by

Refractive index Weight loss rate (%) ΔE _ab Exterior Impact strength (kg _{f ·} cm / cm) Example One 1.507 14.5 0.73 good 58 2 1.500 26.6 1.23 good 62 3 1.500 18.1 0.85 good 62 4 1.499 13.7 0.71 good 58 Comparative Example One 1.507 32.2 1.91 usually 60 2 1.502 36.5 3.73 Bad 57 3 1.500 36.6 2.02 usually 64

As shown in Table 1, the impact modifiers prepared in Examples 1 to 4 had better thermal stability than the impact modifiers of Comparative Examples 1 to 3, and had excellent appearance characteristics such as discoloration stability during injection processing.

The present invention relates to rubber particles prepared by cross-polymerizing styrene-based aromatic compounds and alkyl acrylates in the presence of organosiloxane cross-linked (co) polymer particles, and plastic shells formed by graft copolymerization of vinyl monomers and unsaturated dicarboxylic acids on the rubber particles. It has a high refractive index of 1.490 ~ 1.590, and has the effect of the invention to provide a silicone-based impact modifier and a method for producing the same, excellent in thermal stability and excellent appearance when applied to a thermoplastic resin.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (11)

(A) rubber particles prepared by cross-polymerizing an styrene-based aromatic compound and an alkyl acrylate in the presence of organosiloxane cross-linked (co) polymer particles; And (B) a plastic shell formed by graft copolymerization of a vinyl monomer and an unsaturated dicarboxylic acid on the rubber particles; Silicon-based impact modifier, characterized in that consisting of. The silicone-based impact modifier of claim 1, wherein the silicone-based impact modifier has a refractive index of 1.490 to 1.590. The silicone-based impact modifier of claim 1, wherein the organosiloxane crosslinked polymer has a refractive index in the range of 1.410 to 1.500. The method of claim 1, wherein the organosiloxane is selected from the group consisting of dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane and mixtures or copolymers thereof; The styrene-based aromatic compound is selected from the group consisting of styrene, alphamethylstyrene, divinylbenzene and vinyltoluene; The alkyl acrylate is selected from the group consisting of methyl acrylate, ethyl acrylate and n-butyl acrylate; The vinyl monomer is selected from the group consisting of methyl methacrylate, styrene, acrylonitrile and mixtures thereof; And the unsaturated dicarboxylic acid is selected from the group consisting of maleic acid, fumaric acid, citraconic acid, mesaconic acid and respective anhydrides. The silicone-based impact modifier according to claim 1, wherein the weight ratio of the rubber particles (A) and the plastic shell (B) is 5: 5 to 9: 1. (A) crosslinking-polymerizing a styrene-based aromatic compound and an alkyl acrylate in the presence of organosiloxane crosslinked (co) polymer particles to produce rubber particles; And (B) graft copolymerization of a vinyl monomer and an unsaturated dicarboxylic acid on the rubber particles to form a plastic shell; Method for producing a silicone-based impact modifier, characterized in that consisting of steps. The method of claim 6, wherein the manufacturing method comprises 10 to 90 parts by weight of the organosiloxane crosslinked (co) polymer; 0.01 to 50 parts by weight of the styrene-based aromatic compound; 5 to 90 parts by weight of the alkyl acrylate; 5 to 90 parts by weight of the vinyl monomer; And 0.1 to 10 parts by weight of the unsaturated dicarboxylic acid. The method for producing a silicone-based impact modifier according to claim 6 or 7, wherein allyl methacrylate or triallyl isocyanurate is used as a crosslinking agent when the rubber particles are prepared by crosslinking polymerization. A thermoplastic resin composition comprising the silicone impact modifier of any one of claims 1 to 5. The method of claim 9, wherein the thermoplastic resin is selected from the group consisting of vinyl chloride resin, styrene resin, styrene-acrylonitrile resin, acrylic resin, ester resin, ABS resin and polycarbonate resin. Thermoplastic resin composition. The thermoplastic resin composition of claim 10, wherein the thermoplastic resin comprises 0.5 to 30 parts by weight of the silicone impact modifier based on 100 parts by weight of the polycarbonate resin.