JP4625680B2 - Light diffusive molding - Google Patents

Description

The present invention relates to a light diffusing molded articles obtained from the light-diffusing polycarbonate resin composition. More particularly, it relates to a light diffusing molded articles obtained from the light diffusing polycarbonate resin composition having excellent Izod impact strength.

  Aromatic polycarbonate resin takes advantage of mechanical properties such as excellent Izod impact strength, durability, transparency, heat resistance, and dimensional stability, and is used in electrical, electronic, OA, precision machinery, medical, automobile, miscellaneous goods, and building materials. It is used in a wide range of fields. When used for various illumination lamp covers, lighting signs, liquid crystal displays, etc., the visible light emitted from the light source can be efficiently irradiated without impairing various properties such as the excellent Izod impact strength of the aromatic polycarbonate. In order to reduce glare, a resin composition having a total light transmittance of 50% or more and a dispersity of 40 degrees or more is demanded. As a material suitable for this kind of use, for example, Patent Document 1 discloses that an aromatic polycarbonate has a refractive index different from that of an aromatic polycarbonate and is at least partially crosslinked. A light diffusing polycarbonate resin in which polymer fine particles in the range of 100 μm are dispersed and added has been proposed. Specifically, Patent Document 1 uses a fine particle made of polymethyl methacrylate (PMMA) to which 5 to 30% of a crosslinking agent is added, and has a high light transmittance and light diffusion as compared with the case where calcium carbonate is blended. The data discloses that the properties are good and there is no reduction in impact strength. However, according to the study by the present inventors, a resin composition using crosslinked resin fine particles having a high crosslinking density such as PMMA to which 5% of a crosslinking agent is added is not satisfactory in terms of impact strength. .

Patent Document 2 discloses a light diffusing aromatic polycarbonate resin composition containing an aromatic polycarbonate resin, calcium carbonate, short glass fibers, a phosphite compound and / or a phosphate compound, and a phenolic antioxidant. Since the resin composition contains calcium carbonate and short glass fibers, there is a drawback that the impact strength is very low.
Patent Document 3 proposes a light diffusing resin composition in which a crosslinked resin fine particle having an average particle size of less than 5 μm and a crosslinked resin fine particle having an average particle size of 5 to 10 μm are dispersed in a transparent resin. In the same document, the amount of the crosslinkable monomer used during the polymerization of the crosslinked resin fine particles is preferably in the range of 5 to 20% by weight, but the composition using the crosslinked resin fine particles having such a high crosslinking density is Similar to Patent Document 1, it is considered that the impact strength is lowered.
Patent Document 4 discloses a light diffusing resin composition in which resin fine particles having an average particle diameter of 1 to 30 μm are dispersed as a light diffusing agent in a base resin, and the resin fine particles are fluorine-containing (meth) acrylate esters. A light diffusing resin composition comprising a crosslinkable monomer and another monomer and having a refractive index lower than that of the base resin has been proposed. The monomer is considered to be a resin composition having a low impact strength because it uses fine particles having a high crosslinking density and preferably in the range of 4 to 16% by mass with respect to the total amount of monomers used.
As described above, in the prior art, it was difficult to obtain a light diffusing polycarbonate resin composition excellent in total light transmittance and dispersity without impairing various properties such as excellent Izod impact strength of aromatic polycarbonate. .

Japanese Patent Laid-Open No. 03-143950 JP 09-003310 A JP-A-11-060966 JP 2003-33595 A

An object of the present invention, these prior to solve the problems of the art, without impairing the various properties such as excellent Izod impact strength of an aromatic polycarbonate, the degree of dispersion and the total light transmittance is obtained from a high resin composition, Tsuin'wo It is to provide a light diffusing polycarbonate molded article or a light diffusing polycarbonate molded article having three or more layers of walls .

The present inventors have repeatedly studied to solve the above-mentioned problems, and solved the problem by adding a specific amount of a finely crosslinked acrylic polymer having a relatively low crosslinking density, that is, a relatively high swelling rate, to the aromatic polycarbonate. Knowing what can be done, the present invention has been reached. That is, the gist of the present invention is that 1 to 15 parts by weight of a fine-particle crosslinked acrylic polymer (B) having an average particle diameter of 0.1 to 30 μm is blended with 100 parts by weight of the aromatic polycarbonate resin (A). A light diffusible molded article obtained from a polycarbonate resin composition, wherein the aromatic polycarbonate resin (A) is obtained by a transesterification method and is a branched aromatic polycarbonate having a viscosity average molecular weight of 16,000 to 60,000. There, particulate crosslinked acrylic polymer (B) is, and the measured swelling factor by the following measuring method of 30% or more, and, the degree of dispersion in the total light transmittance of the thickness of 3mm molded article is 50% or more The present invention resides in a twin-wall molded product or a light-diffusible molded product having three or more layers of walls characterized by being 40 ° or more .
[Measurement method of swelling rate]
2.00 g of fine particle cross-linked acrylic polymer was weighed into a graduated test tube, 5 ml of acetone was added thereto to sufficiently wet the fine particles, and 15 ml of acetone was further added and allowed to stand, and the particle layer after 24 hours The value obtained by dividing the volume obtained by dividing the added volume by 20 ml of the added acetone in terms of 100 fraction (%) is defined as the swelling rate.

The present invention has the following particularly advantageous effects, and its industrial utility value is extremely great.
1. The light diffusing molded article according to the present invention is made from a resin composition in which a specific amount of a finely crosslinked acrylic polymer having a relatively low crosslinking density, that is, a relatively high swelling ratio, is blended into an aromatic polycarbonate. Since the components have good affinity, the interface does not separate and the Izod impact strength is excellent.
2. The light diffusive molded article according to the present invention is bright because the total light transmittance of the molded article having a thickness of 3 mm is 50% or more and transmits light relatively well, and yet the dispersity is as high as 40 degrees or more and transmits light. Since it is dispersed, dazzling is suppressed, and it is suitable for uses such as various illumination lamp covers, illumination signboards, and liquid crystal displays.

Hereinafter, the present invention will be described in detail.
Aromatic polycarbonate:
The aromatic polycarbonate resin (A) used in the present invention is not particularly limited, and known methods include an interfacial polymerization method in which an aromatic dihydroxy compound and phosgene are reacted, or a transesterification method in which an aromatic dihydroxy compound and a carbonic acid diester are reacted. The thermoplastic aromatic polycarbonate which may be branched manufactured by the method of this. In the production of a molded product, a branched aromatic polycarbonate is preferably used when a molding method such as extrusion molding, blow molding, or vacuum molding is adopted. Compared to the interfacial polymerization method, the process is relatively simple, and not only can it demonstrate superiority in terms of operation and cost, but also it does not use highly toxic halogen solvents such as phosgene or methylene chloride. An aromatic polycarbonate produced by a transesterification method that is advantageous also from the viewpoint of protection is particularly preferred.

Aromatic dihydroxy compounds:
As typical examples of the aromatic dihydroxy compound as a raw material, 2,2-bis (4-hydroxyphenyl) propane (= bisphenol A), 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis ( 4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) Examples thereof include sulphone, and among these, bisphenol A is particularly preferable.

Branched polycarbonate by interfacial polymerization:
In order to obtain an aromatic polycarbonate branched by the interfacial polymerization method, phloroglucin, 4,6-dimethyl-2,4,6-tris (4-hydroxyphenyl) heptene-2, 4,6-dimethyl-2,4, 6-tris (4-hydroxyphenyl) heptane, 2,6-dimethyl-2,4,6-tris (4-hydroxyphenyl) heptane, 1,3,5-tris (4-hydroxyphenyl) benzene, 1,1 , 1-tris (4-hydroxyphenyl) ethane and the like, or 3,3-bis (4-hydroxyaryl) oxindole (= isatin bisphenol), 5-chloroisatin bisphenol, 5, 7-dichloroisatin bisphenol, 5-bromoisatin bisphenol, etc. as part of the dihydroxy compound And may be used, for example, 0.1 to 2 mol%.

  Further, as a terminal stopper, usual terminal stoppers such as phenol, m- or p-methylphenol, m- or p-propylphenol, p-bromophenol, p-tert-butylphenol, tribromophenol, acetic acid, propion, etc. Fatty acids such as acid, butyric acid, caprylic acid, octylic acid, lauric acid, stearic acid, acetic acid chloride, propionic acid chloride, butyric acid chloride, caprylic acid chloride, octylic acid chloride, lauric acid chloride, stearic acid chloride, hydroxy Alkyl hydroxybenzoates such as methyl benzoate, ethyl hydroxybenzoate, propyl hydroxybenzoate, butyl hydroxybenzoate, octyl hydroxybenzoate, nonyl hydroxybenzoate, stearyl hydroxybenzoate Long-chain alkylphenols such as ester, octylphenol, nonylphenol, laurylphenol, palmitylphenol, stearylphenol, hydroxyphenylacetic acid alkyl esters such as methyl p-hydroxyphenylacetate and ethyl p-hydroxyphenylacetate, octyletherphenol Examples include long-chain alkyl ether phenols such as lauryl ether phenol, palmityl ether phenol, octadecyloxyphenol, and dodecyloxyphenol. The amount used is usually in the range of 0.8 to 10 mol, preferably 2 to 7 mol, per 100 mol of the aromatic dihydroxy compound used, and two or more compounds can be used in combination.

The aromatic polycarbonate resin by the transesterification method is produced by melt condensation polymerization using the aromatic dihydroxy compound and the carbonic acid diester as raw materials in the presence of a transesterification catalyst.
Carbonic acid diester:
The starting carbonic acid diester is usually represented by the following formula (1).

(In the formula (1), A and A ′ are an aliphatic group or substituted aliphatic group having 1 to 18 carbon atoms, or an aromatic group or substituted aromatic group, and A and A ′ may be the same. May be different.)
Specific examples of the carbonic acid diester represented by the general formula (1) include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and di-tert-butyl carbonate, substituted diphenyl carbonates such as diphenyl carbonate, and ditolyl carbonate. However, diphenyl carbonate and substituted diphenyl carbonate are preferred, and diphenyl carbonate is particularly preferred. These carbonic acid diesters may be used alone or in combination of two or more.

In order to produce the transesterified aromatic polycarbonate, bisphenol A is usually used as the aromatic dihydroxy compound, and diphenyl carbonate is used as the carbonic acid diester, but the diphenyl carbonate is 1.01-1 with respect to 1 mol of bisphenol A. It is preferably used in an amount of 0.3 mol, preferably 1.02 to 1.2 mol.
The reaction conditions for the transesterification reaction are not particularly limited, and known methods can be employed.
In order to obtain a branched polycarbonate by the transesterification method, the same branching agent as in the case of the interface method may be used, but by selecting the conditions for the transesterification reaction, without using a branching agent in particular. , Branched polycarbonate can be obtained. In particular, when the conditions as described in JP-A No. 2003-119369 are employed, an aromatic polycarbonate having a branched structure with good fluidity containing a controlled amount of a specific structural unit in the main chain can be obtained. Therefore, it is preferable.

  The aromatic polycarbonate resin (A) used in the present invention preferably has a viscosity average molecular weight of 16,000 or more. Those having a viscosity average molecular weight of less than 16,000 are not preferable because mechanical strength such as surface impact strength is lowered. Viscosity average molecular weight preferable in terms of mechanical strength such as surface impact strength and moldability is in the range of 16,000 to 60,000, and particularly preferably in the range of 18,000 to 50,000. Moreover, it is especially preferable that the viscosity average molecular weight of the aromatic polycarbonate used for shaping | molding which requires high melt tension like extrusion molding, blow molding, and vacuum forming is 20,000-50,000.

Fine particle cross-linked acrylic polymer:
The fine particle crosslinked acrylic polymer (B) used in the present invention is a spherical fine particle obtained by suspension polymerization of a non-crosslinkable acrylic monomer (B1) and a crosslinkable monomer (B2), and measured by the above method. The swelling rate is 30% or more.
As the raw material non-crosslinkable acrylic monomer (B1), a monomer mainly composed of methyl methacrylate and copolymerizable with methyl methacrylate, for example, methacrylic acid esters such as ethyl methacrylate and butyl methacrylate, acrylic It is selected from acrylic acid esters such as methyl acid, ethyl acrylate, butyl acrylate, 2-hydroxy acrylate, methacrylic acid, acrylic acid, styrene, α-methylstyrene, and maleimide. Methacrylic acid esters are preferable.
Examples of the crosslinkable monomer (B2) include ethylene glycol, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and divinylbenzene, with ethylene glycol dimethacrylate being preferred.

  The fine particle cross-linked acrylic polymer (B) used in the present invention is 0.05 to 3 parts by weight, preferably 0. It can be produced by blending 2 to 2 parts by weight, for example, dispersing a monomer in an aqueous solvent using polyvinyl alcohol as a dispersant, performing suspension polymerization, filtering, washing, sieving and drying. In addition, if the compounding quantity of a crosslinkable monomer (B2) is less than 0.05 weight part, since the microparticulate crosslinked acrylic polymer (B) obtained will not disperse | distribute spherically in a molded article, a dispersibility will fall. On the other hand, when the amount of the crosslinkable monomer (B2) exceeds 3 parts by weight, the resulting fine particle cross-linked acrylic polymer has hard particles with a swelling ratio of less than 30%, and a resin composition obtained by blending this This is not preferable because the Izod impact strength is reduced. The particle size of the fine-particle crosslinked acrylic polymer (B) is 0.1 to 30 μm, preferably 0.3 to 20 μm, particularly preferably 0.5 to 10 μm. If the particle size is less than 0.1 μm, the light diffusibility is lowered, and if it exceeds 30 μm, the light diffusibility is uneven, glare is felt, and the Izod impact strength may be lowered.

  In the light diffusing polycarbonate resin composition of the present invention, 1 to 15 parts by weight of the particulate crosslinked acrylic polymer (B) is blended with 100 parts by weight of the aromatic polycarbonate resin (A). If the blending amount of (B) is less than 1 part by weight, the light diffusing effect is not sufficient. The blending amount of the particulate crosslinked acrylic polymer (B) should be adjusted depending on the thickness of the molded product. For example, when the molded product thickness is 1 to 4 mm, the blended particulate crosslinked acrylic polymer (B) is blended. The amount is preferably 1 to 4 parts by weight, and in the case of a molded product thickness of 0.1 to 1 mm, the compounding amount of the particulate crosslinked acrylic polymer (B) is preferably 2 to 10 parts by weight.

Method for producing light diffusing polycarbonate resin composition :
There is no restriction | limiting in particular about the addition time of the fine particle crosslinked acrylic polymer (B) to an aromatic polycarbonate resin (A), and an addition method, Various well-known methods are employable. For example, when (B) is added during the polymerization reaction of the aromatic polycarbonate, at the end of the polymerization reaction or when the aromatic polycarbonate is produced by the transesterification method, the catalyst used for the polymerization is lost with the catalyst deactivator. After the activation, the aromatic polycarbonate resin can be added in a molten state before being pelletized. Alternatively, after blending with an aromatic polycarbonate resin in a solid state such as pellets or powder, it can be kneaded with a single-screw or twin-screw extruder or the like. However, when using an aromatic polycarbonate resin produced by a transesterification method, either during the polymerization reaction, at the end of the polymerization reaction or after deactivation of the catalyst used for the polymerization with a catalyst deactivator, before pelletization It is preferable to add it to the viewpoint of decomposition suppression and coloring suppression.

  The light diffusing polycarbonate resin composition of the present invention includes phosphorous, sulfur, hindered phenol and other heat stabilizers, ultraviolet absorbers, mold release agents, flame retardants, and pigments as long as the object of the present invention is not impaired. Colorants such as dyes, antistatic agents, slip agents, anti-blocking agents, lubricants, antifogging agents, heat ray absorbents, natural oils, synthetic oils, waxes, organic or inorganic fillers such as glass fibers and carbon fibers Other thermoplastic resins such as polyethylene terephthalate can also be added.

  The method for obtaining a molded product using the light diffusing polycarbonate resin composition of the present invention is not particularly limited, and a molding method generally used for thermoplastic resin compositions, for example, injection molding, injection blow molding. Any of injection compression molding, blow molding, extrusion molding, thermoforming, rotational molding and the like can be applied. Extrusion products that require especially tension at melting and excellent shape retention characteristics, thermoforming applications from sheet-shaped products, hollow molded products and large panels by blow molding, twin walls by profile extrusion, walls with three or more layers, etc. For these applications, a light diffusing polycarbonate resin composition using a branched polycarbonate is suitable.

  The light diffusive molded article of the present invention has a hard coat layer, a conductive layer, an antistatic layer, an antifogging layer, an infrared absorbing layer, a light reflective coating, a printed layer, and weather resistance on at least one surface depending on applications. It is preferable that at least one functional layer selected from layers for improvement and the like is provided. The method of providing these functional layers is not particularly limited, and a conventionally known method can be used. For example, a functional layer can be directly provided on the surface of an aromatic polycarbonate resin molded article by means of coextrusion or the like, or the functional layer is separately formed on the surface of a thermoplastic resin film or sheet, and these are combined with the aromatic polycarbonate. A molded product having a functional layer can be obtained by laminating and integrating a resin molded product. In this case, the resin constituting the thermoplastic film or sheet is not particularly limited, but is preferably an acrylic resin such as an aromatic polycarbonate resin or polymethyl methacrylate.

  Examples of the molded article obtained from the light diffusing polycarbonate resin composition of the present invention include molded articles that require excellent total light transmittance and dispersity, and high Izod impact strength. Illuminated signs, liquid crystal displays, and the like are suitable. In addition, as a molded product of a light diffusing polycarbonate resin composition using a branched polycarbonate as the aromatic polycarbonate resin (A), extruded products and sheets that require high melt tension and excellent shape retention characteristics during molding processing Applications such as thermoforming from shaped molded products, hollow molded products by blow molding and large panels, twin walls by profile extrusion, and wall molded products having three or more layers are suitable.

EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to a following example, unless the main point is exceeded. In the following examples, unless otherwise specified, parts are parts by weight and percentages are percentages by weight.
The materials and evaluation methods used in the following examples are as follows.
<Evaluation method>

(1) Total light transmittance: Using a test piece having a length of 90 mm, a width of 50 mm, and a thickness of 3 mm, a transmittance in the thickness direction was measured using a haze meter NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd. did.
(2) Dispersity: Measured using a variable angle photometer GP-5 manufactured by Murakami Color Research Laboratory Co., Ltd. using a test piece having a length of 90 mm, a width of 50 mm, and a thickness of 3 mm. The degree of dispersion refers to an angle at which the transmitted light amount is 50 when a light beam parallel to the thickness direction of the test piece is incident on the center of the test piece and the transmitted light amount parallel to the incident light is 100. In order to efficiently irradiate visible light emitted from a light source and reduce glare of the light source, a material having as high total light transmittance and dispersibility as possible is required.
(3) Izod impact strength with notch: measured according to ASTM D256.
<Material>

(1) PC: aromatic polycarbonate resin ["Iupilon S-3000F" manufactured by Mitsubishi Engineering Plastics Co., Ltd., viscosity average molecular weight = 21000, interfacial polymerization product.
(2) PMMA: Fine-particle cross-linked acrylic polymer, manufactured according to the following production example, with varying amounts of cross-linkable monomer.

Production Example of Fine Particle Acrylic Polymer (B) Polyvinyl alcohol is mixed with ion-exchanged water, 95 parts by weight of methyl methacrylate, ethylene glycol dimethacrylate (EG) in the amount shown in Table 1, and the two After injecting 1 part by weight of peroxide to 100 parts by weight in total, the dispersion was dispersed and subjected to suspension polymerization at 80 ° C. Thereafter, 5 parts by weight of 2-hydroxyethyl methacrylate and 0.25 parts by weight of peroxide were added to the solution, and the polymerization reaction was further carried out at 80 ° C., followed by sequential dehydration, washing with ion-exchanged water, and dehydration to obtain a wet powder. It was. After adding ion-exchanged water and suspending it, adding hydrochloric acid at 50 ° C, adding 10% toluene solution and keeping at 60 ° C, filtering, washing with ion-exchanged water, drying, sieving. As a result, polymethyl methacrylate fine particles B-1 to B-5 having a particle diameter of about 6 μm were obtained. The swelling rate was measured by the above method on the obtained fine particles. The results are shown in Table-1.

* 1: Acrylic polymer particles are melted and not granular.
Examples 1-3 and Comparative Examples 1-3
After dry blending the particulate acrylic polymer produced in the above production example and the aromatic polycarbonate resin in the proportions shown in Table 2, a single screw extruder with a vent with a screw diameter of 40 mm [manufactured by Isuzu Machinery Co., Ltd .: SV- 40], the pellets obtained by melt-kneading at a cylinder temperature of 270 ° C., extruding, and strand cutting were dried at 120 ° C. for 6 hours by a hot air circulation dryer. Thereafter, each evaluation test piece was molded and evaluated with an injection molding machine [M150AII-SJ, manufactured by Meiki Seisakusho Co., Ltd.] at a cylinder temperature of 280 ° C and a mold temperature of 80 ° C. The evaluation results are shown in Table-2.

Example 4
98 parts by weight of a branched polycarbonate resin composition produced by the transesterification method described in Example 2 of JP-A No. 2003-119369 and having a viscosity average molecular weight of 24,500, and the particulate acrylic heavy produced in the above production example After 2 parts by weight of the combined (B-2) was dry blended, a shaping die was attached to the tip of a single screw extruder with a screw diameter of 40 mm [manufactured by Isuzu Machinery Co., Ltd .: SV-40], and the cylinder temperature was 270 ° C. Then, a twin wall having a cross-sectional shape shown in FIG. 1 (the thickness of the wall portion is 0.5 mm, and the distance between the two wall portions is 6,5 mm) was extrusion-molded. In order to evaluate the light diffusibility, the light source (electric lamp) was observed through the obtained twin wall molded body. As a result, although the light source was not directly visible, it was bright and the light diffusibility was good.

Comparative Example 4
A twin wall molded body was obtained in the same manner as in Example 4 except that the fine particle acrylic polymer (B-2) was not blended. When the light source (electric light) was observed through the obtained twin wall molded article, the light source could be confirmed directly and the light diffusibility was poor.

Sectional drawing of the twin wall molded object manufactured in Example 4 and Comparative Example 4. FIG.

Claims (1)

Light obtained from a polycarbonate resin composition obtained by blending 1 to 15 parts by weight of a finely crosslinked acrylic polymer (B) having an average particle size of 0.1 to 30 μm with respect to 100 parts by weight of an aromatic polycarbonate resin (A). A diffusible molded article , wherein the aromatic polycarbonate resin (A) is obtained by a transesterification method, is a branched aromatic polycarbonate having a viscosity average molecular weight of 16,000 to 60,000, B) is characterized in that the swelling ratio measured by the following measurement method is 30% or more, the total light transmittance of a molded product having a thickness of 3 mm is 50% or more, and the degree of dispersion is 40 degrees or more. A twin-wall molded product or a light-diffusible molded product having three or more layers of walls.
[Measurement method of swelling rate]
Weigh 2.00 g of fine particle cross-linked acrylic polymer in a graduated test tube, add 5 ml of acetone to this to sufficiently wet the fine particles, add 15 ml of acetone, and let stand, and the particle layer after 24 hours And the value obtained by dividing the added volume by 20 ml of added acetone in terms of 100 fraction (%) is defined as the swelling rate.

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