JPH04318060A - Light scattering polycarbonate-based resin composition, molded article of light scattering polycarbonate-based resin composition and production thereof - Google Patents

Abstract

PURPOSE:To obtain a light scattering resin composition for producing semitransparent milky molded articles having excellent light scattering properties and excellent impact strength by dispersing specific resin particles as a light scattering substance into a polycarbonate-based resin. CONSTITUTION:(B) Resin particles (e.g. ones having preferably >=330 deg.C melting point or softening point in the case of polycarbonate of component A obtained by reacting bisphenol A with phosgene) having a refractive index different from that of the component A, preferably crosslinked acrylic resin particles (e.g. polymethyl methacrylate) having preferably 0.05-10mum average particle diameter are dispersed into (A) a polycarbonate-based resin having preferably 15,000-50,000, especially 20,000-35,000 molecular weight in a ratio of 100 pts.wt. component A and 0.1-2 pts.wt. component B to give a light scattering polycarbonate-based resin composition. The composition is melted and molded to give a molded article of resin excellent in whole light percent transmission, cloudiness and impact strength.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-scattering polycarbonate resin composition, a light-scattering polycarbonate resin molded article, and a method for producing the same.

0002

[Prior Art] Polycarbonate resins have traditionally been used as transparent and impact-resistant resins, but in translucent applications where light diffusion is important, extender pigments and white pigments are used to reduce the transparency. It is common to mix

[0003] An example of a translucent application is a lighting cover, and it is desirable that the optical characteristics be milky white and bright (high amount of light transmission), and that the outline of the light source cannot be seen through (high amount of diffused transmission). Usually, the molded product is 1 to 3 mm.
Generally, the total light transmittance (the ratio of the amount of light transmitted to the amount of incident light) is 35 to 50%, and the haze value (the ratio of the amount of diffused transmission to the amount of light transmitted) is 90% or more.

Barium sulfate or calcium carbonate with a thickness of 0.1 to 10μ is used as an extender pigment, and titanium oxide with a thickness of 0.2 to 0.3μ is used as a white pigment. Both are kneaded and added to the molten resin to create the desired translucent state.

On the other hand, a method is also known in which a thermoplastic resin having a different refractive index, such as polymethyl methacrylate, is added to a polycarbonate resin.

[0006]

[Problems to be Solved by the Invention] However, if an extender pigment is added to a polycarbonate resin to increase the haze value, it is necessary to add a large amount of extender pigment. This accelerates thermal decomposition of the material, reduces impact strength, and causes yellowing.

[0007]Also, white pigments such as titanium oxide can increase the haze value by adding a small amount, but the total light transmittance becomes low (less than 50%), making it difficult to use as a lighting cover to increase brightness. It is undesirable, and like extender pigments, it also has the disadvantage of accelerating thermal decomposition during melt molding of polycarbonate resins.

A method of adding a thermoplastic resin with a different refractive index, such as polymethyl methacrylate, to polycarbonate resin has been devised, but in either case, a phenomenon of poor compatibility with a pearl-like luster occurs in the polycarbonate resin, or the polycarbonate There was a problem in that the impact strength of the resin was reduced.

[0009]

[Means for Solving the Problems] The present inventors have made extensive studies in view of the above-mentioned circumstances, and have found that the resin particles do not melt under the heating and melting conditions of the polycarbonate resin, and have a refractive index different from that of the polycarbonate resin. We have discovered that by using a composition using resin particles of 30%, it is possible to obtain a molded product that does not impair impact strength, has an appropriate amount of light transmission, and does not allow the outline of the light source to be seen through. The invention was completed.

That is, the present invention provides polycarbonate resin (
In A), the polycarbonate resin (A) does not melt under the heating melting conditions of the polycarbonate resin (A).
The object of the present invention is to provide a light-scattering polycarbonate resin composition in which resin particles (B) having a refractive index different from that of the present invention are dispersed.

Polycarbonate resin (A) according to the present invention
) include aromatic polycarbonates, aliphatic polycarbonates, etc., and any known and commonly used polycarbonates can be used; One example is merging.

Examples of the dioxy compounds include bisphenol A, bisphenol F, hydroquinone, resorcinol, bis(4-hydroxyphenyl)alkane,
Examples include bis(4-hydroxyphenyl)cycloalkane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, and the like.

Specific examples of the resin (A) include aromatic polycarbonates obtained by reacting bisphenol A, bisphenol F, etc. with phosgene, and aliphatic polycarbonates obtained by reacting hydrogenated bisphenol A, hydrogenated bisphenol F, etc. with phosgene. Polycarbonate, aromatic-aliphatic copolycarbonate prepared by reacting a mixture of bisphenol A and hydrogenated bisphenol A with phosgene, bisphenol A
A mixture of bisphenol A and propylene glycol was reacted with phosgene, a mixture of bisphenol A and 1,6-hexanediol was reacted with phosgene, and a mixture of bisphenol A and 1,6-hexanediol was reacted with phosgene. Aliphatic-aromatic copolycarbonates such as those made by reacting a mixture of bisphenol A and tetrabromobisphenol A with phosgene, those made by reacting a mixture of bisphenol A and bisphenol C with phosgene, and bisphenol A. Aromatic copolycarbonates such as those obtained by reacting a mixture of and paraxylene glycol with phosgene, those obtained by reacting bisphenol A and adipic acid with phosgene,
Ester bond-containing polycarbonates such as those made by reacting bisphenol A and adipic acid with phosgene, urethane bond-containing aromatic polycarbonates made by reacting phosgene, which is a reaction product of bisphenol A and piperazine, and bisphenol A bischloroformate with phosgene. Examples include thiocarbonate bond-containing aromatic polycarbonates reacted with thiophosgene.

[0014] The resin (A) has a molecular weight of 15,000 to 500
00 is preferred, and 2,000 to 35,000 is particularly preferred. The resin particles (B) used in the present invention, which do not melt under the heat-melting conditions of the polycarbonate resin (A) and have a refractive index different from that of the polycarbonate resin (A), are appropriately selected from known and commonly used resin particles. and use it. When a polycarbonate prepared by reacting bisphenol A and phosgene is used as the resin (A), the resin particles (B) preferably have a melting point or a softening point of 330° C. or higher.

For example, if a resin (A) with a refractive index of 1.60 is used, a resin with a refractive index different from that of the resin (A),
For example, resin particles with a refractive index of 1.50 may be used. The type of resin for the resin particles (B) is not particularly limited, and examples thereof include epoxy resins, acrylic resins, phenol resins, urea resins, olefin resins, fluorine resins, silicone resins, etc. . Among these various resins, acrylic resins are preferred.

Of course, the acrylic resin may be any resin that does not melt under the heating and melting conditions of the polycarbonate resin (A) and has a refractive index different from that of the polycarbonate resin (A). It can be anything, but
Crosslinked acrylic resins are preferred.

The acrylic resin contains (meth)acrylic acid ester as an essential component, and if necessary, in the presence of a catalyst,
It can be easily obtained by polymerizing with (meth)acrylic acid and a crosslinkable monomer. Acrylic resins are easily obtained, for example, by emulsion polymerization, soap-free polymerization, seed polymerization, dispersion polymerization, and the like. Below, the description of (meth)acrylic acid is as follows:
Let it represent both methacrylic acid and acrylic acid.

Examples of (meth)acrylic esters include methyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and ethyl (meth)acrylate. .

Monomers that can have a crosslinked structure during polymer formation include, for example, divinylbenzene, ethylene glycol di(meth)acrylate, propylene glycol (
meth)acrylate, trimethylolpropane(tri)
Acrylate, pentaerythritol tetraacrylate, bisphenol A di(meth)acrylate, dicyclopentanyl di(meth)acrylate, dicyclopentenyl di(meth)acrylate, N-methylol (meth)
Examples include acrylamide.

The refractive index of the resin particles (B) is not particularly limited and needs to be appropriately selected depending on the type of resin (A) used. It is preferable to use a material having a refractive index lower than that of . For reference, for example, the refractive index of polycarbonate is about 1.59, and that of a copolymer of methyl (meth)acrylate and divinylbenzene is about 1.49.

The particle size of the resin particles (B) is not particularly limited, but is preferably less than 10 μm in terms of the impact strength of the resin (A) itself and the smoothness of the surface of the molded product.
Among them, 0.05 to 5.0 μm, especially 0.2 to 2.5 μm
It is preferable that Resin particles with smaller particle size (B
) has the advantage that a desired translucent state can be obtained by adding only a small amount. The shape of the resin particles (B) is not particularly limited, but preferably spherical particles.

[0022] The amount of resin particles (B) used in the present invention is not particularly limited;
) can be increased or decreased as appropriate depending on the thickness of the composition of the present invention containing as an essential component. Usually, it is 0.1 to 3.0 parts by weight per 100 parts by weight of resin (A).

Since the resin particles (B) do not melt or decompose at the molding temperature of the resin (A) used,
) can form dispersed phases with different refractive indexes. Resin particles (
When B) is a spherical particle, it is possible to form a dispersed layer with different refractive indexes more uniformly, so that the appearance is different from the translucent state obtained with conventionally used white pigments and extender pigments. Become.

[0024] The molding temperature of the composition of the present invention is appropriately selected depending on the type of resin (A) used, but for example, in the case of polycarbonate made by reacting bisphenol A and phosgene, it is usually 240 to 330°C. It is.

[0025] In addition to the resin particles (B), conventionally used white pigments and extender pigments may be used in appropriate combinations in the composition of the present invention in order to satisfy the desired optical properties. Examples of white pigments include titanium oxide and plastic pigments (hollow resin particles), and examples of extender pigments include barium sulfate, barium carbonate, calcium carbonate, talc, mica, clay, and kaolin.

[0026] The resin particles (B) can be mixed with the resin (A) using a commonly used tumbler, ribbon blender, V-type blender, high-speed mixer, kneader, etc., and the mixed material can be simply passed through an extruder etc. The desired composition can be obtained simply by melt-kneading.

When preparing the composition of the present invention, conventionally known additives such as flame retardants, mold release agents, antistatic agents, ultraviolet absorbers, antioxidants, pigments, and lubricants may be added. Of course it's a good thing.

The composition of the present invention thus obtained is:
It can be molded by known and commonly used molding methods, such as injection molding, extrusion molding, blow molding, compression molding, and powder molding.

The composition of the present invention can be used in known and commonly used applications, such as reflective plates, signs, signals, lighting covers, blinds, window glasses, roofs, fishing lines, packaging films and sheets, optical fiber cladding materials, optical waveguide cladding materials, etc. can be used.

[0030]

[Examples] Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. All parts in the examples are parts by weight. Examples 1 to 2 100 parts of bisphenol A polycarbonate pellets with a molecular weight of 25,000 vacuum-dried at 120°C for 4 hours
．． Add 4 μm and 2.0 μm cross-linked polymethyl methacrylate spherical particle powders at the addition rates listed in Table 1,
After mixing well, use a twin screw extruder (L/D=25)
The pellets were extruded at a resin temperature of 270°C.

[0031] After vacuum drying the pellets at 120°C for 4 hours, they were dried in an in-line screw injection molding machine (with mold clamping force of 4).
0t, mold 80℃), a 50 x 50mm square plate with a thickness of 2.5mm and JIS K711 at a resin temperature of 280℃.
1/8 inch Izod impact test specimens were molded in accordance with No. 0. In order to evaluate the translucency of the flat plates obtained among these molded pieces, the total light transmittance and haze value were measured according to JIS K7105, and the hue was also observed.

[0032] The obtained molded piece was also subjected to an Izod test according to JIS K7110. Furthermore, 27 pellets
A film having a thickness of about 40 to 50 μm was obtained by heating and melt pressing at 0° C., and the state of dispersion of particles in the polycarbonate was examined using an optical microscope with a magnification of 200 times.

Table 1 shows the evaluation results for various particles. Comparative Examples 1 to 6 Instead of crosslinked polymethyl methacrylate spherical particle powder,
Rutile titanium oxide powder (Comparative Example 1), calcium carbonate powder (Comparative Example 2), zinc oxide powder (Comparative Example 3), precipitated barium sulfate powder (Comparative Example 4), powdered polymethyl methacrylate (Comparative Example 5). The same operation as in the example was performed except that the same procedure was used, and the same evaluation was performed. The evaluation results for each are shown in Table-1. Reference Example Using only the bisphenol A polycarbonate pellets having a molecular weight of 25,000 from Example 1, the same operations as in the Examples were carried out, and the same evaluations were performed. The evaluation results are also shown in Table-1.

In Example 1, cross-linked polymethyl methacrylate MP-3100 manufactured by Soken Kagaku Co., Ltd. was used, and in Example 2, cross-linked polymethyl methacrylate MR-2 manufactured by Soken Chemical Co., Ltd.
In Comparative Example 1, uncrosslinked polymethyl methacrylate MP-1000 manufactured by the same company was used as G.

[0035]

[Table 1]

[0036] As can be seen from Table 1, while the conventional molded product is inferior in one of the following performances: total light transmittance, haze value, and impact strength, the molded product of the composition of the present invention is inferior in all of these properties. It is clear that it is superior across the board.

[0037]

Effects of the Invention The polycarbonate resin composition of the present invention contains, as a light-diffusing substance, resin particles that do not melt under the heat-melting conditions of the polycarbonate resin and have a refractive index different from that of the polycarbonate resin. Because it is dispersed, it is easy to obtain polycarbonate molded products that are translucent, have good light diffusion, are milky white, and have excellent impact strength, satisfying all aspects of total light transmittance, haze value, and impact strength. It has a remarkable effect.

Claims (6)

[Claims] Claim 1: The polycarbonate resin (A) contains resin particles (B) that do not melt under the heating and melting conditions of the polycarbonate resin (A) and have a refractive index different from that of the polycarbonate resin (A). Dispersed light-scattering polycarbonate resin composition. 2. The composition according to claim 1, wherein the resin particles (B) are acrylic resin particles. [Claim 3] The resin particles (B) have a melting point or a softening point of 3.
The composition according to claim 1, which is acrylic resin particles having a temperature of 30°C or higher. Claim 4: The resin particles (B) have an average particle diameter of 0.0.
Claim 2: The particles are acrylic resin particles with a diameter of 5 to 10.0 μm.
Or the composition according to 3. 5. A light-scattering polycarbonate resin molded article in which resin particles having a refractive index different from that of the polycarbonate resin (A) are dispersed in a polycarbonate resin. 6. The polycarbonate resin (A) contains resin particles (B) that do not melt under the heating melting conditions of the polycarbonate resin (A) and have a refractive index different from that of the polycarbonate resin (A). A method for producing a light-scattering polycarbonate resin molded product, which is dispersed and then heated and melt-molded.