KR101717442B1 - Cross-linked methacrylate copolymer for polycarbonate, polycarbonate composition - Google Patents

Abstract

The present invention relates to a polycarbonate resin composition having improved scratch resistance, and more particularly, to a polycarbonate resin composition comprising a crosslinked methacrylate copolymer bead for a polycarbonate resin.

Description

Technical Field The present invention relates to a crosslinked methacrylate copolymer bead and a polycarbonate resin composition for a polycarbonate resin,

The present invention relates to a polycarbonate resin composition having improved scratch resistance, and more particularly, to a polycarbonate resin composition comprising a crosslinked methacrylate copolymer bead for a polycarbonate resin.

Polycarbonate resins are widely used as engineering plastics because they have excellent heat resistance, impact resistance, dimensional stability, transparency, hardness and flame retardancy compared with other engineering plastics. However, the polycarbonate resin is required to have excellent flame retardancy and excellent appearance characteristics against the external environment for use in applications such as electrical and electronic products and office automation equipment due to problems such as poor scratch resistance and weatherability, such as low pencil hardness, There are many limitations in the use.

Therefore, various research and development are being carried out to supplement this. For example, attempts have been made to commercialize polycarbonate by copolymerizing other monomers to improve the scratch resistance of the polycarbonate. However, economical difficulties arise due to the use of expensive special monomers and ancillary processes.

As another method, a method of blending polycarbonate with a resin excellent in scratch resistance is attempted as compared with a polycarbonate such as polymethylmethacrylate, but the compatibility is poor and the impact resistance of the polycarbonate is reduced, and the improvement of the scratch resistance It is not large.

US Patent Publication No. 2012-0121845 attempts to improve the surface hardness by applying silicon dioxide nanoparticles to a polycarbonate substrate. However, due to secondary processing for coating, process cost is increased, processing time is increased, and haze increase rate This is a high problem.

Korean Patent Laid-Open Publication No. 10-2014-0120026 discloses a technique for copolymerizing alkyl methacrylate, aryl methacrylate and vinyl silane monomers to polycarbonate resins in order to maintain transparency and scratch resistance of polycarbonate , The silane-based compound has a higher reactivity than the carbon-based compound and is difficult to handle, and the vinylsilane-based compound has a disadvantage that it is difficult to apply to suspension and emulsion polymerization because it reacts with water.

Therefore, it is necessary to develop a technique for producing a polycarbonate resin composition having excellent scratch resistance while maintaining the impact resistance of the polycarbonate resin.

Korean Patent Publication No. 10-2014-0120026 U.S. Published Patent Application No. 2012-0121845

Disclosure of the Invention The present invention aims at solving the problems of the prior art by blending a crosslinked methacrylate copolymer bead with a polycarbonate resin having excellent impact resistance and high strength but poor external appearance due to the external environment, Provided is a polycarbonate resin composition improved in scratch resistance while maintaining impact properties.

(A) suspending a mixture comprising a mixed monomer of alkyl methacrylate and aryl methacrylate and a crosslinking agent to prepare a crosslinked methacrylate copolymerized bead; And

(b) blending the crosslinked methacrylate-based copolymer beads and the polycarbonate;

The present invention also provides a method for producing a polycarbonate resin composition for improving scratch resistance.

In one embodiment of the present invention, the mixed monomer is prepared by mixing 50 to 90 wt% of an alkyl methacrylate monomer and 10 to 50 wt% of an aryl methacrylate monomer, and the polycarbonate resin composition for improving scratch resistance . ≪ / RTI >

In one embodiment of the present invention, the cross-linking agent may include 0.05 to 10 parts by weight of a crosslinking agent based on 100 parts by weight of the mixed monomer. However, the present invention is not limited to the method of manufacturing the polycarbonate resin composition for improving scratch resistance .

The suspension polymerization of the step (a) of the present invention can be exemplified by a method of producing a polycarbonate resin composition for improving scratch resistance, which is produced by multi-stage polymerization.

The suspension polymerization of the present invention can be exemplified by a method of producing a polycarbonate resin composition for improving scratch resistance, which is produced by carrying out a one-step polymerization at 70 to 85 ° C and a two-step polymerization at 85 to 100 ° C But is not limited thereto.

In one embodiment of the present invention, the bead may have an average particle diameter of 0.5 to 100 占 퐉. The method may further include a method of producing a polycarbonate resin composition for improving scratch resistance.

The present invention provides a polycarbonate resin composition for improving scratch resistance comprising 5 to 40 wt% of crosslinked methacrylate copolymerized beads and 60 to 95 wt% of polycarbonate according to the present invention.

The present invention can provide a polycarbonate resin composition improved in surface hardness and has excellent scratch resistance with improved appearance due to external environment while maintaining transparency and impact resistance.

Further, the process for producing the polycarbonate resin composition of the present invention can be easily applied to various types of molded articles because of the simple manufacturing process and molding method.

Hereinafter, the present invention will be described in more detail. In the following description of the present invention, a detailed description of known configurations and functions will be omitted.

Unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

In order to achieve the above-mentioned object, the present invention relates to a polycarbonate resin composition comprising a polycarbonate resin having improved scratch resistance while maintaining excellent transparency, impact resistance and flame retardancy of a polycarbonate resin by blending crosslinked methacrylate copolymerized beads subjected to suspension polymerization in a polycarbonate resin A method for producing a resin composition is provided.

Hereinafter, the present invention will be described step by step.

The present invention relates to a process for preparing a crosslinked methacrylate copolymerized bead by suspending a mixture comprising a mixture of an alkyl methacrylate monomer and an aryl methacrylate monomer and a crosslinking agent; And

(c) blending the crosslinked methacrylate-based copolymer beads with polycarbonate;

A polycarbonate resin composition for improving scratch resistance, and a process for producing the polycarbonate resin composition.

The alkylmethacrylate monomer is not particularly limited, but preferably has a high surface hardness. For example, a monomer having a C1-C30 alkyl group may be used, but the present invention is not limited thereto. Nonlimiting examples of the alkyl methacrylate monomers include methyl methacrylate, ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, 2-hexyl methacrylate, and the like, Methyl methacrylate, but is not limited thereto, and it is possible to use all the alkyl methacrylate monomers which can be used for the suspension polymerization.

The arylmethacrylate monomer is not particularly limited, but it is preferable that the arylmethacrylate monomer is capable of enhancing the mixing power between the alkylmethacrylate monomer and the polycarbonate resin while increasing the surface hardness. For example, the arylmethacrylate monomer may include C6- Or an arylalkyl group, but is not limited thereto. Nonlimiting examples of the arylmethacrylate include phenylmethacrylate and biphenylmethacrylate. However, the arylmethacrylate monomer is not limited thereto, and any of the arylmethacrylate monomers that can be used for the suspension polymerization may be used .

The mixed monomer may be used in a mixture of two or more kinds. Preferably, the mixed monomer may be a mixed monomer containing 50 to 90 wt% of alkyl methacrylate and 10 to 50 wt% of aryl methacrylate, but is not limited thereto. When the above-mentioned arylmethacrylate is polymerized at less than 10 wt%, compatibility with polycarbonate is lowered. If it exceeds 50 wt%, transparency and scratch resistance of the resin composition may be lowered.

 Next, the step of preparing a crosslinked methacrylate-based copolymerized bead by suspending the mixed monomer with a crosslinking agent.

Crosslinked methacrylate-based copolymerized beads can be prepared by suspension polymerization of a mixed monomer containing the methacrylic monomer, which is a technical feature of the present invention, and a crosslinking agent. The scratch resistance of the polycarbonate resin composition is improved by using the crosslinked methacrylate copolymer beads prepared as described above, and the heat resistance is improved due to the crosslinked structure of the beads.

In addition, by blending the crosslinked methacrylate-based copolymerized beads with the polycarbonate resin, the resin is prevented from being loosened during blending of the general acrylic resin and the polycarbonate resin, thereby preventing phase separation caused by the incompatibility between the resins .

For example, when an aryl methacrylate copolymerized bead is prepared and mixed with a polycarbonate resin, an excellent scratch resistance of the methacrylate copolymer resin can be imparted while maintaining transparency.

The crosslinking agent used for preparing the crosslinked methacrylate copolymerized bead of the present invention can be widely used as long as it is a crosslinking agent that can be used in the methacrylate suspension polymerization. The crosslinking agent used in the present invention may be any of crosslinking agents for preparing acrylic copolymerized beads. Nonlimiting examples of the crosslinking agent include aryldimethacrylic acid, ethylene glycol dimethacrylate, and ethylene glycol dimethacrylic acid But is not limited thereto. The content of the crosslinking agent is preferably 0.05 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the mixed monomer, but is not particularly limited. If the amount of the crosslinking agent is less than 0.05 part by weight, crosslinking efficiency may be lowered and impact resistance may be impaired. When the amount of the crosslinking agent is more than 10 parts by weight, the gloss may decrease and haze may increase.

In another technical aspect of the present invention, in the production of the crosslinked methacrylate-based copolymerized bead, a crosslinked methacrylate-based copolymerized bead can be prepared by suspending a mixed monomer obtained by mixing two or more methacrylate-based monomers .

The suspension polymerization process adopted in the present invention is a mixed monomer obtained by mixing two or more kinds of methacrylate monomers and is an optimal process capable of copolymerizing a microspheroidal crosslinked methacrylate bead having a particle size most suitable for the present invention Is a very important step in the production of the crosslinked methacrylate beads of the present invention.

Since the suspension polymerization method for producing the crosslinked methacrylate beads of the present invention is carried out in water based on water, various factors such as particle size, stability, or dispersibility are affected depending on the polymerization environment, Reaction conditions can be a very important factor. Accordingly, the present invention relates to a method for producing a crosslinked methacrylate-based bead capable of improving appearance properties such as scratch resistance while maintaining the specific physical properties of a conventional polycarbonate resin by mixing with a polycarbonate resin, Was used for the first time.

According to still another aspect of the present invention, there is provided a bead having an average particle size of 0.5 to 100 탆 in which the average particle diameter of the crosslinked methacrylate beads prepared by the suspension polymerization method described below is 0.5 to 100 탆, 50 占 퐉 is contained in the polycarbonate resin composition, the impact strength and gloss of the composition are prevented, the uniform dispersion in the polycarbonate resin is obtained, transparency is maintained, and the scratch resistance of the methacrylate copolymer resin is most effectively imparted And it is the best because it can prevent quality problems such as pinholes on the surface after processing.

The suspension polymerization according to the present invention is not particularly limited, but multi-stage suspension polymerization is particularly preferable. For example, the suspension polymerization can be carried out through two or more multi-stage suspension polymerization steps.

In the suspension polymerization of two or more stages, after the polymerization is stopped, the beads are prevented from being crushed at the time of drying, and the spherical shape is maintained as it is, thereby minimizing the light and refraction phenomenon and maintaining transparency. It is thought that the cause is not precisely known but multi-stage polymerization is carried out to increase the cross-linking density of the surface by increasing the temperature at the rear end, thereby preventing the distortion due to shrinkage during drying.

In a non-limiting example of the multistage polymerization method according to the present invention, a reaction product containing the mixed monomer and a cross-linking agent is reacted at 70 to 85 ° C for 50 to 100 minutes to effect suspension polymerization in one step, Crosslinked methacrylate-based copolymer beads prepared through a step of two-step suspension polymerization for 50 minutes are incorporated in the polycarbonate composition, it is possible to prepare a polycarbonate resin composition having physical properties more excellent in appearance, which is a weak point of the polycarbonate composition It is the best.

The mixed resin for producing the crosslinked methacrylate-based copolymerized bead of the present invention may further contain additives as required. Examples of such an additive include a cross-linking agent in a mixed resin obtained by mixing two or more kinds of methacrylate monomers such as an initiator, a chain transfer agent or a dispersant, All are available.

If necessary, beads can be prepared by additionally adding a heat stabilizer, a UV stabilizer, a chain transfer agent, and the like.

The initiator can be widely used as long as it is a conventional initiator that can be used in the methacrylate suspension polymerization. For example, azobisisobutyronitrile, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,2'-azobis (4-methoxy-2,4 -Dimethyl pentanitrile), dimethyl-2,2'-azodiisobutyric acid salt, tert-butylperoxy-3,5,5-trimethylhexanoate, 2,2'-azobis (2- Amidinopropane) dihydrochloride, di-n-propylperoxydicarbobonite, and the like can be used. The content of the initiator is most preferably 0.01 to 1 part by weight based on 100 parts by weight of the mixed resin obtained by mixing the methacrylate monomers alone or in combination, but is not limited thereto.

The chain transfer agent can be used to maintain the fluidity of the polymethyl methacrylate resin through controlling the molecular weight of the methacrylate resin. Non-limiting examples of the chain transfer agent used in the present invention are alkylmercaptans having 1 to 12 carbon atoms in the alkyl group and one thiol functional group or polythiomercapto groups having two or more thiol functional groups. The alkylmercaptan may be, but is not limited to, isopropylmercaptan, tertiary butylmercaptan, normal butylmercaptan, normal amylmercaptan, normal octylmercaptan, and normal dodecylmercaptan. The chain transfer agent may be contained in an amount of 0.1 to 5 parts by weight, preferably 0.2 to 1 part by weight, based on 100 parts by weight of a mixed resin obtained by mixing a methacrylate monomer alone or two or more kinds thereof. When the chain transfer agent is contained in the above range, it is more preferable to secure sufficient flowability for the purpose of the present invention.

The dispersing agent is not limited as long as it is a conventional dispersing agent used in suspension polymerization. However, the dispersing agent used in the present invention may be a polymer such as polyvinyl alcohol, cellulose, starch, methylcellulose, polymethylmethacrylate copolymer, And inorganic dispersing aids such as calcium carbonate, magnesium carbonate, calcium sulfate and sodium sulfate may be used, but the present invention is not limited thereto. The content of the dispersant may be 0.001 to 2 parts by weight based on 100 parts by weight of a mixed resin obtained by mixing two or more kinds of methacrylate monomers, but is not limited thereto.

As a next step, the present invention can provide a method for producing a polycarbonate resin composition comprising the step of comprising the crosslinked methacrylate-based copolymer beads and the polycarbonate resin prepared above.

The polycarbonate resin to be used in the present invention is not particularly limited, but is preferably a resin having a flowability (MI) of 10 to 40 g / min as measured under a load of 1.2KG at 300 DEG C and blending with the crosslinked methacrylate copolymer beads And is most favorable for producing a polycarbonate resin composition having improved scratch resistance while maintaining heat resistance and impact resistance.

As described above, the present invention prevents the phase separation phenomenon due to incompatibility between the resin and the polycarbonate resin when blending the acrylic resin and the polycarbonate resin by blending the crosslinked methacrylate copolymer beads and the polycarbonate resin prepared by suspension polymerization Particularly, in the case of blending the copolymerized beads with a monomer containing a monomer mixture of a polycarbonate resin and an aryl methacrylate monomer of the present invention, it is possible to improve the scratch resistance of the methacrylate copolymer resin while maintaining transparency of the polycarbonate resin Thereby imparting the desired physical properties. In particular, transparency can be further increased or maintained by maximizing compatibility during the blending.

The polycarbonate resin composition may be prepared by blending the crosslinked methacrylate copolymer beads with a polycarbonate resin. For example, the crosslinked methacrylate copolymer beads and the polycarbonate resin may be heated and melted and blended, But may be blended using a screw compressor or a twin screw compressor. The blending ratio may be 5 to 40 wt% of crosslinked methacrylate copolymer beads and 60 to 95 wt% of polycarbonate resin, but is not particularly limited.

The polycarbonate resin composition obtained by the blending can be molded into various forms depending on the use such as compression molding, transfer molding, injection molding, blow molding, extrusion molding, or lamination molding.

The polycarbonate resin composition of the present invention is not particularly limited, but may further contain additives as required.

Such an additive may include an impact modifier such as a butyl acrylate rubber or a butadiene rubber for the purpose of impact reinforcement. In order to improve weather resistance, an ultraviolet stabilizer, a light stabilizer, an antioxidant or a mixture thereof may be further added But is not limited thereto.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, the following examples and comparative examples are merely illustrative, and the present invention is not limited by the following examples.

Preparation of methacrylate copolymer

[Example 1]

1500 g of a mixed monomer consisting of 75% by weight of methyl methacrylate, 5% by weight of ethyl methacrylate and 20% by weight of phenyl methacrylate was added to a 5-liter reactor in an amount of 2000 g of distilled water, 5 g of a 5% polyvinyl alcohol solution (POVALPVA217, Kuraray) 0.15 g of n-octylmercaptan, 1.5 g of 2,2'-azobisisobutyronitrile and 1.5 g of ethylene glycol dimethacrylate were added and dispersed in the aqueous phase with stirring at 500 rpm, Polymerization was carried out. The first suspension polymerization was carried out at a reaction temperature of 80 ° C, and the polymerization solution was heated to 80 ° C. After 70 minutes, a polymerization peak was generated, and the temperature was raised to 95 ° C. for 30 minutes to effect secondary suspension polymerization. To prepare a crosslinked methacrylate copolymerized bead having an average particle diameter of 50 탆. The beads obtained by the suspension were washed three times with distilled water and dehydrated repeatedly and dried in a fluidized bed dryer. 20wt% of the obtained beads and 80wt% of polycarbonate (LG-DOW1300-10) were mixed and extruded, and then the injection specimens were produced and evaluated for their physical properties. The results are shown in Table 1.

[Example 2]

The procedure of Example 1 was repeated except that 7.5 g of ethylene glycol dimethacrylate was used, and the properties of the injection specimen were evaluated. The results are shown in Table 1.

[Example 3]

The procedure of Example 1 was repeated except that 15 g of ethylene glycol dimethacrylate was used, and the properties of the injection specimen were evaluated. The results are shown in Table 1.

[Example 4]

The procedure of Example 1 was repeated except that a mixed monomer was prepared from 70 wt% of methyl methacrylate, 10 wt% of ethyl methyl acrylate and 20 wt% of phenyl methyl acrylate and 0.75 g of ethylene glycol dimethacrylate , And the properties of the injection specimens were evaluated. The results are shown in Table 1

[Example 5]

Except that beads were prepared by suspending the mixture at 80 DEG C for 70 minutes to prepare an injection specimen and evaluating the physical properties thereof. The results are shown in Table 1.

[Comparative Example 1]

The procedure of Example 1 was repeated except that ethylene glycol dimethacrylate was not included, and the properties of the injection specimen were evaluated. The results are shown in Table 1.

[Comparative Example 2]

Except that the mixed monomer was prepared by mixing 95 wt% of methyl methacrylate and 5 wt% of ethyl methacrylate, and the properties of the injection specimens were evaluated after manufacturing the injection specimens. The results are shown in Table 1.

[Comparative Example 3]

Except that the mixed monomer was prepared by mixing 95 wt% of methyl methacrylate and 5 wt% of phenyl methacrylate, and the properties of the injection specimens were evaluated after manufacturing the injection specimens. The results are shown in Table 1.

[Comparative Example 4]

The procedure of Example 1 was repeated except that crosslinked copolymerized beads were not mixed with 100 wt% of polycarbonate resin in Example 1, and the properties of the injection molded specimens were evaluated. The results are shown in Table 1.

Property measurement

(Pencil hardness measurement)

After the pencil was fixed with a load of 0.5 kg and an angle of 45 degrees, the surface of the specimen was scratched by pencil hardness and visually inspected according to ASTM D3363.

(Measurement of light transmittance)

The resin composition prepared according to the present invention was injection-molded to a thickness of 3.2 mm and then measured for light transmittance according to ASTM D1003.

(Haze measurement)

The resin composition prepared according to the present invention was injection molded to a thickness of 3.2 mm and then haze was measured according to ASTM D1003.

(Impact strength measurement)

The notched Izod impact strength (kg.cm/cm) was measured at room temperature according to the ASTM D256 measurement method.

Table 1 above shows the results of confirming that the polycarbonate resin compositions of Examples 1 to 5 prepared by the production method according to the present invention had improved physical properties (pencil hardness, transparency, haze, impact strength). In particular, Examples 1 and 3 in which bead was produced by performing the multistage suspension polymerization according to the present invention showed the best properties.

From the results shown in Table 1, it can be seen that the polycarbonate resin composition (Comparative Example 4) containing no crosslinked acrylic copolymerized bead according to the present invention has excellent transparency and haze, but the pencil hardness is remarkably decreased. In the case of the polycarbonate resin composition containing the crosslinked acrylic copolymerized beads according to the present invention, it is confirmed that the pencil hardness is greatly increased, but also the excellent appearance characteristics and high transparency that maintains good transparency and haze properties are secured.

In addition, from the physical properties of Comparative Examples 1 and 3, it is confirmed that the impact strength is remarkably reduced since the cross-linking agent is not included, resulting in a very low impact strength. In particular, in the case of Comparative Example 2 which does not contain phenyl methacrylate, which is a kind of aryl methacrylate, it is confirmed that the physical properties of the transmittance and the haze are drastically lowered.

In addition, in Comparative Examples 2 and 3 in which the methacrylate monomer did not contain aryl methacrylate capable of imparting compatibility with the polycarbonate, the transmittance was higher than those of Examples 1 to 5 containing aryl methacrylate It can be confirmed that the temperature is very low and the haze is increased.

Claims (8)

(a) preparing a crosslinked methacrylate copolymerized bead by suspending a mixture containing 50 to 90 wt% of two or more alkyl methacrylate monomers and 10 to 50 wt% of a phenyl methacrylate monomer and a crosslinking agent; ;
(b) blending the crosslinked methacrylate-based copolymer beads and the polycarbonate;
Wherein the polycarbonate resin composition is prepared by a method comprising the steps of:
delete The method according to claim 1,
Wherein the cross-linking agent comprises 0.05 to 10 parts by weight of a cross-linking agent based on 100 parts by weight of the mixed monomer.
The method according to claim 1,
Wherein the suspension polymerization is carried out by multiplying the polycondensation of the polycarbonate resin composition.
5. The method of claim 4,
Wherein the suspension polymerization is carried out at a temperature of from 85 to 100 DEG C after one step polymerization by reacting at 70 to 85 DEG C, followed by two stages of polymerization at 85 to 100 DEG C, to obtain a polycarbonate resin composition for improving scratch resistance.
The method according to claim 1,
Wherein the blending comprises 5 to 40 wt% of the crosslinked methacrylate copolymer beads and 60 to 95 wt% of the polycarbonate.

The method according to claim 1,
Wherein the beads have an average particle diameter of 0.5 to 100 mu m.
A polycarbonate resin composition comprising 5 to 40 wt% of a crosslinked methacrylate-based copolymer bead produced according to any one of claims 1 to 7 and 60 to 95 wt% of a polycarbonate.