KR101025860B1 - Light diffusing particles having impact resistance and moldings obtained therefrom - Google Patents

Abstract

The present invention provides light diffusing particles that can be applied to the architectural or lighting milky sheet to give not only light diffusion but also impact resistance to produce a highly functional acrylic sheet, which is methyl methacrylate or (meth) acrylate type A cabinet layer having an average particle diameter of 150 nm to 250 nm composed of a glass phase polymer obtained from a co-unit; An intermediate layer having a thickness of 200 to 300 nm grafted to the inner layer layer and comprising a copolymer (styrene-rubber polymer) of at least one monomer selected from butyl acrylate or butadiene and at least one monomer selected from styrene or styrene derivatives; And a three-layer structure of an outer layer having a thickness of 200 to 300 nm composed of a glassy polymer obtained from a methyl methacrylate or a (meth) acrylate-based copolymer, grafted on the intermediate layer, and having a refractive index of 1.52 to 1.6. Such particles may exhibit a light diffusing effect while maintaining impact resistance as a conventional impact modifier, and the composition including the same may be used for construction or lighting through extrusion, injection, or casting molding without including a separate impact modifier. It is useful as a sheet.

Description

Light diffusing particles having impact resistance and moldings obtained therefrom {Light Diffusing Polymeric Beads with Impact Resistance and its Preparation Method and product etc}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to light diffusing particles useful in the manufacture of architectural or lighting sheets, and more particularly to organic particles capable of simultaneously imparting impact resistance and light diffusing effect.

Conventionally, inorganic particles such as TiO ₂ and organic particles such as styrene beads have been used as light diffusing agents for construction and lighting. In the case of the double styrene beads, the transparency of the particles themselves is higher than those of the inorganic particles, and they are used together with methyl methacrylate resin to give excellent light diffusion effect. However, when transparency is excellent but high impact resistance is required, it has a disadvantage of using an additional impact modifier in order to exhibit an impact reinforcing effect.

In other words, the conventional organic light diffusing agent for building or lighting imparts excellent light diffusing effect to the sheet of transparent resin, but it is troublesome to additionally use an impact agent to reinforce the impact resistance. This adds cost burden and increases process difficulty for uniform dispersion of the particles.

Accordingly, there is a need for the development of organic particles that can simultaneously provide impact resistance and light diffusion effects.

Thus, the inventors of the present invention, in the manufacture of an acrylate-based impact modifier known as an impact modifier, in particular an impact modifier made of an inner layer, an intermediate layer, and an outer layer to adjust the thickness of the intermediate layer to have a light diffusion effect, In addition to the impact reinforcing effect and the light diffusing effect was found to be useful as light diffusing particles to complete the present invention.

Accordingly, it is an object of the present invention to provide light diffusing particles that can be applied to architectural or lighting milky sheets to provide not only light diffusivity but also impact resistance to produce a highly functional acrylic sheet.

Light diffusion particles having impact resistance of the present invention for achieving the above object is an inner layer of 150 ~ 250nm average particle diameter composed of a glass polymer obtained from methyl methacrylate or (meth) acrylate-based copolymer; An intermediate layer having a thickness of 200 to 300 nm, which is grafted on the inner layer layer and is composed of a copolymer (styrene-rubber polymer) of at least one monomer selected from butyl acrylate or butadiene and at least one monomer selected from styrene or styrene derivatives. ; And a three-layer structure of an outer layer having a thickness of 200 to 300 nm composed of a glassy polymer obtained from a methyl methacrylate or a (meth) acrylate-based copolymer, grafted on the intermediate layer, and having a refractive index of 1.52 to 1.6. It is characterized by.

Hereinafter, the present invention will be described in detail.

Looking at the method for producing light-diffusion particles having impact resistance of the present invention,

First, methylmethacrylate or (meth) acrylate-based co-units (hereinafter, 'first monomer') are emulsion-polymerized to form an inner layer. Specifically, after a solution in which ion exchanged water, an emulsifier, a crosslinking agent, and a part of a first monomer are mixed in a nitrogen stream is added to a reactor, the solution is heated and stirred, and the temperature of the solution reaches 50 to 90 ° C. Emulsion polymerization is carried out by adding a polymerization initiator, and when a seed emulsion is formed, the polymerization of the glass-like polymer can be prepared by continuously adding the remaining amount of the first monomer dropwise to prepare an emulsion. In addition, the polymerization initiator or the crosslinking agent may be further added to prepare an emulsion of the glass polymer.

Here, the average particle diameter of the glassy polymer (inner layer) depends on the first monomer content and the amount of emulsifier used. Lowering the content of the first monomer to reduce the size of the glassy polymer can form more rubbery phase in the light-diffusing particles, and also more transparent styrene-rubber phase (intermediate layer) with different refractive indices. It is advantageous to make it possible.

In forming the inner layer, the amount of the first monomer is preferably 5 to 30% by weight of all the monomers constituting the light diffusion particles. Moreover, it is preferable to adjust the average particle diameter of a glassy polymer (inner layer) to 150-250 nm by adjusting the quantity of an emulsifier. If the average particle diameter of the inner layer is smaller than 150 nm, the size of the final particles cannot be increased. If the inner particle layer is larger than 250 nm, the content of the intermediate layer imparting the light diffusion effect and impact resistance cannot be increased. There can be. And it is preferable to use a crosslinking agent so that it may be 0.05-2.5 weight part with respect to 100 weight part of whole monomer layers.

In the step of forming the inner layer, it is preferable to emulsify the polymer so that the ratio of the first monomer to the glass-like polymer is about 93 to 95%. If the conversion is less than 93%, the thermal stability of the polymer is lowered and thermal decomposition occurs during processing. The methyl methacrylate copolymer used in the said process consists of 1 or more types of monomers chosen from the group which consists of a (meth) acrylic-acid alkylaryl ester of C1-C20 and a (meth) acrylic-acid fluoroalkyl ester of C1-C20. In this case, the content of methyl methacrylate is preferably at least 80% by weight of the inner monomer composition. The ion-exchanged water used in the above process is produced through the ion exchanger, and it is preferable to use the one having a resistance of 1 MΩ or more under a nitrogen stream. Ion-exchanged water may be used to 80 to 800 parts by weight based on 100 parts by weight of the first monomer.

Next, an intermediate layer grafted to the inner layer is formed. Specifically, at least one monomer selected from butyl acrylate or butadiene and at least one monomer selected from styrene or styrene derivatives (hereinafter referred to as a second comonomer) The emulsion is polymerized to graf or harden the intermediate layer on the inner layer. More specifically, the emulsion of the glass phase polymer (inner layer) is continuously stirred at 60-90 ° C. while adding an emulsifier, a crosslinking agent, and a second comonomer dropwise thereto, and the polymerization initiator is added again when the polymerization is completed. do. In this case, a crosslinking agent may be additionally added. By such emulsion polymerization, a styrene-rubber polymer (intermediate layer) is grafted onto the glass polymer (inner layer).

In the light-diffusion particles of the present invention, the higher the content of the styrene-rubber phase (intermediate layer), the higher the impact resistance and the light diffusivity. In particular, it is very important that the weight of the styrene-rubber polymer is 50 to 80% by weight of the total monomer weight constituting the light-diffusion particles. If the weight of the intermediate layer is less than 50% by weight of the total monomer weight, the impact resistance and light diffusivity deteriorate. The average thickness of the crosslinked styrene-rubber polymer is 200 to 300 nm, more preferably 230 to 280 nm.

In the intermediate layer forming step, it is preferable to use a crosslinking agent so that 0.5 to 2.5 parts by weight based on 100 parts by weight of the intermediate layer composition monomer. In the above process, for the thermal stability of the intermediate layer, it is preferable that the conversion of the comonomer is 93% or more. In the above process, when the dropping time and the polymerization time of the second comonomer are not sufficient, or when an emulsifier (surfactant) is not used, problems of agglomeration of monomers occur.

The mixing ratio of the monomers constituting the intermediate layer includes 30 to 60% by weight of one or more monomers selected from butyl acrylate or butadiene in the intermediate layer composition monomer, and the one or more monomers selected from styrene or styrene derivatives to 40 of the intermediate layer composition monomers. It contains at 70 weight%. At this time, if the content of at least one monomer selected from styrene or styrene derivative is less than 40% by weight in the intermediate layer composition monomer, it does not have a desired refractive index, and light diffusion is reduced. There may be a problem.

After the intermediate layer is formed as described above, a process of finally emulsion-polymerizing the same methyl methacrylate or (meth) acrylate-based unit (hereinafter referred to as a third monomer) as the first monomer is performed to form an outer layer. Specifically, in the emulsion in which the two-stage emulsion polymerization is completed, the polymerization initiator and the third monomer as the matrix component are gradually added dropwise, and the polymerization is continued, and when the emulsion polymerization is completed, the polymerization initiator is added again, and then the chain transfer agent is added. Injecting to prepare an emulsion of particles in which a glass-like polymer (outer layer) is grafted onto the intermediate layer (styrene-rubber polymer). In this step, no emulsifier and a crosslinking agent are used, and thus, the glass-like polymer constituting the outer layer is not crosslinked. In the above process, a chain transfer agent is added to adjust the molecular weight, and the chain transfer agent includes (i) sulfur compounds such as n-butyl (di) sulfide having 1 to 10 carbon atoms, (ii) butylamine and triethyl (methyl). An amino compound such as an amine, (iii) a halogen compound such as chloroform, tetrachloro (bromo) methane, or the like, an alcohol such as (iv) ethanol, or (v) acetone. It is preferable to use so that 0.02-5 weight part with respect to 100 weight part of 3 monomers. The 3rd monomer uses the same thing as a 1st monomer. In this case, 1.0 to 4.5 mol of the third monomer is used relative to 1 mol of the first monomer. The average thickness of the grafted third monomer is preferably adjusted to be 250 to 350 nm, more preferably 280 to 320 nm. If the thickness of the outer layer is less than 250nm, the usability with the base resin (PMMA) at the time of processing is lowered and thicker than 350nm may have a problem of an increase in manufacturing cost due to the use of excess raw material. In the process of forming the outer layer, it is preferable to emulsify the polymer so that the ratio of the third monomer to the glassy polymer is 98% or more. When the conversion rate is low, the thermal stability and mechanical properties of the polymer are low, resulting in thermal decomposition during processing.

Examples of the emulsifier (surfactant) that can be used in the above series of steps include anionic emulsifiers such as sodium, ammonium, or gallium salts of alkyl sulfates having 4 to 30 carbon atoms, in situ reactive emulsifiers or amphiphilic emulsifiers. Specifically, sodium dodecyl sulfate, sodium dioctyl sulfosuccinate, sodium dodecyl benzene sulfate, etc. are used. In order to improve the thermal stability of the polymer, the emulsifier is preferably a water-soluble substance. An emulsifier is used in 0.1-4 weight part with respect to 100 weight part of all monomers.

Examples of the crosslinking agent include 1,2-ethanediol di (meth) acrylate, 1,3-propanedioldi (meth) acrylate, 1,4-butanedioldi (meth) acrylate and 1,5-pentanedioldi (meth) ) Acrylic, 1,6-hexanediol di (meth) acrylate divinylbenzene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, triethylene Glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate or allyl (meth) acrylate, and the like. It is preferable that these usage-amounts are 0.1-15 weight part with respect to 100 weight part of all monomers.

Examples of the polymerization initiator include cumene hydroperoxide, potassium persulfate or sodium persulfate, and azo water-soluble initiators. The amount of these used is preferably 0.02 to 2.0 parts by weight based on 100 parts by weight of the total monomers.

When the three-step emulsion polymerization as described above is completed, a particle emulsion having a three-layer structure is obtained. The emulsion is slowly added dropwise to an excess of 0.1-2% magnesium sulfate or calcium chloride solution preheated to 50-100 ° C. to stir to precipitate particles in the emulsion. The precipitated particles were washed three to four times with distilled water at about 70 ° C. and then dried in a vacuum oven at 80 ° C. for about 24 hours to produce particles having a light diffusing effect while having impact resistance as a final product. Instead of using salt, it can be dried by spray dryer.

The light diffusing particles thus obtained have a refractive index of about 1.52 to 1.6. If the refractive index is less than 1.52, the light diffusing effect due to the difference in refractive index is reduced, and if it is larger than 1.6, the rubber phase content of the intermediate layer is reduced so that the impact resistance becomes worse. .

When the light diffusing particles of the present invention are applied to an acrylic resin such as methyl methacrylate, the light diffusing particles are also given impact resistance while maintaining excellent light diffusivity. In addition, since the workability is good, physical properties are remarkably improved even when directly extruded or cast in the form of powder during processing.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the following examples are provided to more easily understand the present invention, but the present invention is not limited to these examples.

Example 1

1000 g of ion-exchanged water was added to a 3 L vessel, and the internal temperature was heated to 80 ° C. under a nitrogen stream, followed by 170.3 g of methyl methacrylate, 9.0 g of ethyl acrylate, 0.7 g of allyl methacrylate, and 1.35 g of sodium dioctylsulfosuccinate. 38 g of the mixed solution was added to the reactor and stirred for 15 minutes. Thereafter, 15 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 60 minutes. When the polymerization was almost complete, the remaining mixed solution was added dropwise to the reactor at a rate of 5 g per minute. After completion of the dropwise addition, the reaction was further performed for 60 minutes to prepare an emulsion of a glassy polymer (inner layer) having an average particle diameter of 180 nm (conversion rate 94%).

25 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 15 minutes. A mixed solution of 130 g of butyl acrylate, 200 g of styrene, 6.5 g of allylmethacrylate, and 2.5 g of sodium dioctylsulfosuccinate was added at a rate of 8 g per minute. Was added dropwise to the reactor. After completion of the dropwise addition, 25 ml of 1% potassium persulfate solution was added. After completion of the dropwise addition, the polymerization was further performed for 240 minutes, and then 12 ml of 1% potassium persulfate solution was added to the reactor to further polymerize for 15 minutes to prepare an emulsion of particles in which styrene-rubber polymer (intermediate) was grafted on the inner layer. (Conversion rate 94%).

A mixed solution of 86 g of methyl methacrylate, 4.5 g of ethyl acrylate, and 0.15 g of dodecyl mercaptan (made by chain transfer) was added dropwise to the reactor at a rate of 3 g per minute, and then polymerization was further performed for 100 minutes to complete the polymerization. An emulsion of particles in which the glassy polymer was grafted onto the phase was prepared.

The emulsion was added dropwise to a 1% magnesium sulfate solution preheated to 80 ° C. while stirring to prepare a powdered solid. The powder was washed three times with distilled water at 70 ° C. after filtration, and dried in a vacuum oven at 60 ° C. for 2 days to prepare light-diffusing particles having impact resistance.

Example 2

1000 g of ion-exchanged water was added to a 3 L vessel, and the internal temperature was heated to 80 ° C. under a nitrogen stream, followed by 170.3 g of methyl methacrylate, 9.0 g of ethyl acrylate, 0.7 g of allyl methacrylate, and 1.35 g of sodium dioctylsulfosuccinate. 38 g of the mixed solution was added to the reactor and stirred for 15 minutes. Thereafter, 15 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 60 minutes. When the polymerization was almost complete, the remaining mixed solution was added dropwise to the reactor at a rate of 5 g per minute. After completion of the dropwise addition, the reaction was further performed for 60 minutes to prepare an emulsion of a glassy polymer (inner layer) having an average particle diameter of 180 nm (same as in Example 1, conversion rate of 94%).

25 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 15 minutes. Then, a mixed solution of 110 g of butyl acrylate, 220 g of styrene, 6.5 g of allyl methacrylate, and 2.5 g of sodium dioctylsulfosuccinate was added at a rate of 8 g per minute. Was added dropwise to the reactor. After completion of the dropwise addition, 25 ml of 1% potassium persulfate solution was added. After completion of the dropwise addition, the polymerization was further performed for 240 minutes, and then 12 ml of 1% potassium persulfate solution was added to the reactor to further polymerize for 15 minutes to prepare an emulsion of particles in which styrene-rubber polymer (intermediate) was grafted on the inner layer. (Conversion rate 94%).

A mixed solution of 86 g of methyl methacrylate, 4.5 g of ethyl acrylate, and 0.15 g of dodecyl mercaptan (made by chain transfer) was added dropwise to the reactor at a rate of 3 g per minute, and then polymerization was further performed for 100 minutes to complete the polymerization. An emulsion of particles grafted with a glassy polymer on it was prepared.

The emulsion was added dropwise to a 1% magnesium sulfate solution preheated to 80 ° C. while stirring to prepare a powdered solid. The powder was washed three times with distilled water at 70 ° C. after filtration, and dried in a vacuum oven at 60 ° C. for 2 days to prepare light-diffusing particles having impact resistance.

In the same manner as in Example 2, light diffusing particles having impact resistance were prepared, but the intermediate layer monomer composition was changed as in Table 1 below.

Example 3

1000 g of ion-exchanged water was added to a 3 L vessel, and the internal temperature was heated to 80 ° C. under a nitrogen stream, followed by 170.3 g of methyl methacrylate, 9.0 g of ethyl acrylate, 0.7 g of allyl methacrylate, and 1.35 g of sodium dioctylsulfosuccinate. 38 g of the mixed solution was added to the reactor and stirred for 15 minutes. Thereafter, 15 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 60 minutes. When the polymerization was almost complete, the remaining mixed solution was added dropwise to the reactor at a rate of 5 g per minute. After completion of the dropwise addition, the reaction was further performed for 60 minutes to prepare an emulsion of a glassy polymer (inner layer) having an average particle diameter of 180 nm (same as in Example 1, conversion rate of 94%).

25 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 15 minutes. Then, a mixed solution of 150 g of butyl acrylate, 180 g of styrene, 6.5 g of allyl methacrylate, and 2.5 g of sodium dioctylsulfosuccinate was added at a rate of 8 g per minute. Was added dropwise to the reactor. After completion of the dropwise addition, 25 ml of 1% potassium persulfate solution was added. After completion of the dropwise addition, the polymerization was further performed for 240 minutes, and then 12 ml of 1% potassium persulfate solution was added to the reactor to further polymerize for 15 minutes to prepare an emulsion of particles in which styrene-rubber polymer (intermediate) was grafted on the inner layer. (Conversion rate 94%).

A mixed solution of 86 g of methyl methacrylate, 4.5 g of ethyl acrylate, and 0.15 g of dodecyl mercaptan (made by chain transfer) was added dropwise to the reactor at a rate of 3 g per minute, and then polymerization was further performed for 100 minutes to complete the polymerization. An emulsion of particles grafted with a glassy polymer on it was prepared.

The emulsion was added dropwise to a 1% magnesium sulfate solution preheated to 80 ° C. while stirring to prepare a powdered solid. The powder was washed three times with distilled water at 70 ° C. after filtration, and dried in a vacuum oven at 60 ° C. for 2 days to prepare light-diffusing particles having impact resistance.

In the same manner as in Example 2, light diffusing particles having impact resistance were prepared, but the intermediate layer monomer composition was changed as in Table 1 below.

Comparative Example 1

700 g of ion-exchanged water was added to a 3 L vessel and heated to 70 ° C. under a nitrogen stream, followed by 85 g of methyl methacrylate, 10 g of ethyl acrylate, 0.45 g of allyl methacrylate, and 0.78 g of sodium dioctylsulfosuccinate. 20 g of the mixed solution was added to the reactor and stirred for 15 minutes. Then, 8 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 60 minutes. When the polymerization was almost complete, the remaining mixed solution was added dropwise to the reactor at a rate of 5 g per minute. After completion of the dropwise addition, the reaction was further performed for 60 minutes to prepare an emulsion of a glass polymer (inner layer) having an average particle diameter of 120 nm [conversion rate 94%].

13 ml of 1% potassium persulfate solution was added thereto, followed by stirring for 15 minutes, followed by a mixed solution of 142 g of butyl acrylate, 20 g of styrene, 3.3 g of allyl methacrylate, 312 g of tinuvin, and 1.3 g of sodium dioctylsulfosuccinate. Was added dropwise to the reactor at a rate of 8 g per minute. After completion of the dropwise addition, 13 ml of 1% potassium persulfate solution was added. After completion of the dropwise addition, the polymerization was further performed for 240 minutes, and then 6 ml of 1% potassium persulfate solution was added to the reactor to further polymerize for 15 minutes, thereby preparing an emulsion of particles in which a rubbery polymer (intermediate layer) was grafted onto the inner layer [ 96% conversion rate].

A mixed solution of 333 g of methyl methacrylate, 17.0 g of ethyl acrylate, and 0.6 g of dodecyl mercaptan (chain transferase) was added dropwise to the reactor at a rate of 3 g per minute, followed by further polymerization for 100 minutes to complete the polymerization. An emulsion of particles on which a glassy polymer (outer layer) was grafted onto was prepared.

The emulsion was added dropwise to a 1% magnesium sulfate solution preheated to 80 ° C. to prepare a powdered solid. The powder was washed three times with distilled water at 70 ° C. after filtration and dried for 24 hours in a vacuum oven at 80 ° C. to prepare particles.

Specific manufacturing conditions and the thickness of each layer according to the Examples and Comparative Examples are shown in Table 1 below.

Example 1 Example 2 Example 3 Comparative Example 1 Interlayer Monomer Composition (g) Butyl acrylate 130 110 150 142 butadiene - - - - Styrene 200 220 180 20 Layer thickness (nm) Cabinet layer (average particle diameter) 180 180 180 120 Mezzanine 250 230 240 135 Outer layer 300 310 300 320

Experimental Example

The refractive index of each particle obtained from the above Examples and Comparative Examples was measured, and a specimen was prepared using the same. Extruded specimens are prepared by blending 95 parts by mass of polymethyl methacrylate (PMMA) resin (CP51 grade by Lucite) with 5 parts by weight of impact resistant light diffusing particles prepared from the above examples.

After mixing the composition as described above by extrusion molding to prepare a specimen of 2 mm thickness and evaluated the various physical properties and the results are shown in Table 2 below.

The specific property evaluation method is as follows.

(1) refractive index (particle)

Use Elipsometer

(2) impact strength

 ASTM D-256 Method

(3) flexural strength

ASTM D-790 Method

(4) Flexural modulus

ASTM D-790 Method

(5) light diffusivity

Light Transmittance Light Scattering Using Cary UV

Example 1 Example 2 Example 3 Comparative Example 1 Refractive index 1.560 1.590 1.540 1.490 Impact strength (kgcm / cm) 6.9 6.5 7.1 7.0 Flexural Strength (kg / ㎠) 900 800 940 870 Flexural modulus (kg / ㎠) 24,000 22,000 25,000 23,000 Light Diffusion (%) 81 87 80 60

From the results of Table 2, the specimens containing the particles prepared from Examples 1 to 3 have a light diffusion effect while having impact resistance, whereas the particles of Comparative Example 1 have excellent impact resistance but a light diffusion effect On the side, it can be seen that the lack.

As described in detail above, according to the present invention is composed of the inner layer, the middle layer and the outer layer, the particles obtained by adjusting the composition and thickness of the intermediate layer can exhibit a light diffusion effect while maintaining the impact resistance as a conventional impact modifier, The composition including the same is useful as a building or lighting sheet through extrusion, injection or casting molding without including a separate impact modifier.

Claims (4)

A cabinet layer having an average particle diameter of 150 to 250 nm composed of a glass phase polymer obtained from methyl methacrylate or a (meth) acrylate-based copolymer; An intermediate layer having a thickness of 200 to 300 nm grafted to the inner layer layer and comprising a copolymer (styrene-rubber polymer) of at least one monomer selected from butyl acrylate or butadiene and at least one monomer selected from styrene or styrene derivatives; And It is grafted on the intermediate layer, has a three-layer structure of the outer layer of 200 ~ 300nm thickness consisting of a glass-like polymer obtained from methyl methacrylate or (meth) acrylate-based copolymer, impact resistance with a refractive index of 1.52 ~ 1.6 Light diffuser having a. The method of claim 1, wherein the styrene-rubber polymer is obtained from 30 to 60% by weight of at least one monomer selected from butyl acrylate or butadiene and 40 to 70% by weight of at least one monomer selected from styrene or styrene derivatives. Light diffusing particles having impact resistance. A molding obtained from a composition comprising light diffusing particles having impact resistance according to claim 1. 4. The molding according to claim 3, which is a building or lighting sheet obtained by extruding, injecting or casting a composition containing light diffusing particles.