JPH0948922A - Transparent thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transparent thermoplastic resin composition having excellent in transparency and impact resistance and reduced in an increase in haze upon a temperature change brought about by e.g. heating by specifying the refractive indices of the rubber phase and the resin phase and specifying the difference between the changes in them upon a temperature change. SOLUTION: This transparent thermoplastic resin composition is the one prepared by dispersing particles having a core/shell multilayer structure in which a rubber phase of a glass transition temperature of 0 deg.C is dispersed in a transparent thermoplastic resin and satisfying the replationship: 0.01>nR23-nP23<0 (wherein nR23 is the refractive index of the rubber phase at 23 deg.C, and nP23 is the refractive index of the resin phase at 23 deg.C when they are independently measured) and the relationship: 0.00025>|dnR/dT-dnP/dT| (wherein dnR/dT is the change in the refractive index of the rubber phase upon a temperature change in a range of 23-70 deg.C, and dnP/dT is the change in the refractive index of the resin phase when they are independently measured). It is desirable that the glass transition temperature of the thermoplastic resin is 50 deg.C or above and that the particles of the core/shell multilayer structure are those of a three-layer structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent thermoplastic resin composition, and more particularly to a transparent thermoplastic resin which is excellent in transparency and impact resistance and has a reduced change in haze value due to temperature change. The present invention relates to a plastic resin composition.

[0002]

2. Description of the Related Art As a method for improving the impact resistance of a thermoplastic resin, it is common practice to disperse a rubber phase having elasticity in a hard resin discontinuously. At that time, the introduction of a diene elastomer is common, but various introductions of an acrylic elastomer have been studied from the viewpoint of weather resistance. As a modified resin using an acrylic elastomer, various multilayer structure polymers based on a core-shell structure and having a combination of a soft layer and a hard layer have been studied (Japanese Patent Publication No. 54-18298 and Japanese Examined Patent Publication). 55-2
No. 7576, Japanese Patent Publication No. 62-41241, etc.).
Although these have an excellent effect of improving impact resistance, there is a large increase in haze due to temperature changes such as heating, and the application range of rubber-modified transparent thermoplastic resin typified by impact-resistant transparent acrylic resin is limited. There was a point.

Several methods for improving the increase in haze due to heating have also been investigated (Japanese Patent Laid-Open No. 63-19925).
No. 8, etc.). This method is to reduce the increase in haze due to heating by increasing the graft ratio between the resin layer and the rubber layer, but it does not have sufficiently satisfactory physical properties for practical use.

[0004]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a transparent thermoplastic resin which, in addition to the excellent transparency of the transparent thermoplastic resin, has excellent impact resistance and which has a reduced increase in haze due to temperature changes such as heating. It is to provide a plastic resin composition.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in view of such a situation, the rubber phase and the resin phase have a specific difference in refractive index at a specific temperature, and further, the rubber phase and the resin phase. The inventors have found that the above problems can be solved by limiting the difference in the amount of change in the refractive index with respect to the phase, and have completed the present invention.

That is, according to the present invention, a core having a rubber phase having a glass transition temperature of 0 ° C. or less in a transparent thermoplastic resin.
A transparent thermoplastic resin composition in which shell-type multi-layered particles are dispersed, wherein the refractive index (nR23) of the rubber phase and the refractive index (nP23) of the resin phase at 23 ° C. when measured individually are as follows: In the relationship of (I), and the temperature change amount of the refractive index of the rubber phase (dnR / dT) and the temperature change amount of the refractive index of the resin phase (dnP / dT) at 23 to 70 ° C. when measured individually. And have a relationship of the following formula (II) is a transparent thermoplastic resin composition.

0.01> nR23-nP23> 0 (I) 0.00025> | dnR / dT-dnP / dT | (II)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as described above,
It is necessary that the refractive index (nR23) of the rubber layer and the refractive index (nP23) of the resin layer at 23 ° C., which are individually measured, have the relationship of the above formula (I).

The rubber-modified transparent thermoplastic resin typified by impact-resistant acrylic resin has a problem that its application range is limited due to a large increase in haze due to heating, but this phenomenon has a high glass transition temperature ( (Hereinafter sometimes referred to as Tg) and a resin phase such as an acrylic resin which is in a glass state at a general use temperature and a rubber phase which has a low Tg and is in a rubber state at a general use temperature are mixed. Due to.

It is well known that the physical properties of polymers differ at Tg as a boundary, but the amount of change in refractive index with temperature change also greatly differs between Tg and Tg. Micro-Brownian motion is released on the temperature side higher than Tg, and each part of the molecule can thermally oscillate in a considerably large range, so that the linear expansion coefficient is large. The coefficient is relatively small. The temperature change of the refractive index can be approximately estimated from the temperature change of the molecular refraction and the linear expansion coefficient, but the temperature change of the molecular refraction can be almost ignored compared to the effect of the linear expansion coefficient. The temperature change is simply calculated from the linear expansion coefficient. Therefore, the temperature change amount of the refractive index is large when the temperature is Tg or higher, and is small when the temperature is Tg or lower. From the above, even if the resin phase and the rubber phase have the same refractive index at a certain temperature,
A change in temperature causes a difference in their refractive index, which causes an increase in haze due to a change in temperature. However, it has been surprisingly found that it is possible to significantly suppress the increase in haze due to heating while minimizing the increase in haze at room temperature within a certain refractive index range. That is, the increase in haze due to heating can be suppressed when nR23-nP23 (hereinafter, nR23-nP23 is referred to as Δn23) is 0.01>Δn23> 0, and more preferably 0.008>Δn23> 0. This is the case. When Δn23 is 0.01 or more, the haze at room temperature sharply increases and the practicality as a transparent resin is greatly impaired, which is not preferable, and when Δn23 is 0 or less, the refraction of the resin phase and the rubber phase during heating is decreased. The rate difference increases,
It is not preferable because the haze increases and the practicality is impaired.

In the present invention, it is necessary to satisfy not only the relation of the above formula (I) but also the relation of the above formula (II).

That is, the temperature change amount of the refractive index of the rubber phase (dnR / dT) and the temperature change amount of the refractive index of the resin phase (dn)
P / dT) difference is less than 0.00025 / K,
It is preferably less than 0.0002 / K as a method of maintaining good transparency even at room temperature and during heating.

Generally, the temperature change amount of the refractive index of Tg or less of the amorphous resin is 1 to 2 × 10 ^-4 / K, whereas that of Tg or more is 3 to 5 × 10 ^-4. It is known to increase with / K. The rubber-modified thermoplastic resin has a Tg at room temperature in a resin phase that is Tg or less at room temperature.
Because of the structure in which the rubber phase is dispersed as described above, components having different refractive index temperature changes are mixed.
In order to have both transparency at room temperature and transparency at the time of heating, the difference in the temperature change amount of the refractive index between the resin phase and the rubber phase is small, that is, the value is 0.00025 / K.
It needs to be smaller.

Examples of the transparent thermoplastic resin in the present invention include methacrylic resin containing methyl methacrylate as a main component, styrene resin containing styrene as a main component, methyl methacrylate-styrene resin containing methyl methacrylate and styrene as a main component, acrylonitrile and Examples thereof include acrylonitrile-styrene resin containing styrene as a main component, polycarbonate resin, vinyl chloride resin and the like. This transparent thermoplastic resin can be obtained by known methods such as suspension polymerization, solution polymerization, emulsion polymerization and bulk polymerization.

The glass transition temperature of the transparent thermoplastic resin used in the present invention is preferably 50 ° C. or higher from the viewpoint of heat resistance.

The transparent thermoplastic resin composition of the present invention comprises the above-mentioned transparent thermoplastic resin and core-shell type multilayer structure particles dispersed therein. The core-shell type multilayer structured particles may be structured particles having two or more layers, but are preferably structured particles of three layers in the present invention. Therefore, the three-layer core-shell structured particles will be described below.

Examples of the monomer forming the first layer (core) of the core-shell type three-layer structure particles in the present invention include, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate. Such as methacrylic acid ester, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, acrylic acid ester such as benzyl acrylate, styrene,
Aromatic vinyl compounds such as vinyltoluene and α-methylstyrene, N-substituted maleimide compounds such as N-cyclohexylmaleimide, N-o-chlorophenylmaleimide and N-tert-butylmaleimide, acrylonitrile,
Examples thereof include vinyl cyanide compounds such as methacrylonitrile, which may be used alone or in combination of two or more. Also,
Examples of polyfunctional monomers include allyl methacrylate, allyl acrylate, triallyl cyanurate, allyl cinnamate, allyl sorbate, diallyl maleate, diallyl phthalate, diallyl fumarate, ethylene glycol di (meth) acrylate, polyethylene. Examples thereof include polyfunctional monomers such as glycol di (meth) acrylate, divinylbenzene, 1,3-butylene glycol di (meth) acrylate, and divinylbenzene, which may be used alone or in combination of two or more.

The first layer is preferably a resin layer having a glass transition temperature of 50 ° C. or higher. Glass transition temperature is 5
When the temperature is 0 ° C. or lower, the heat resistance of the transparent thermoplastic resin composition becomes insufficient, the temperature dependency of the haze of the transparent thermoplastic resin composition becomes large, and the haze during heating tends to increase. In addition, the first layer is preferably a crosslinked structure for impact resistance and temperature dependence of haze. Allyl methacrylate is particularly preferable as the polyfunctional monomer constituting the first layer, and the addition amount thereof is 0.0
It is preferable to use 1 to 1% by weight. The refractive index of the first layer is preferably as close as possible to the refractive index of the transparent thermoplastic resin.

Examples of the monomer forming the second layer (intermediate layer) of the core-shell type three-layer structure particles in the present invention include acrylate alkyl esters such as butyl acrylate and 2-ethylhexyl acrylate; Aromatic vinyl compounds such as styrene and vinyltoluene, methacrylic acid esters such as methyl methacrylate and benzyl methacrylate,
Examples thereof include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, which may be used alone or in combination of two or more. Further, as the polyfunctional monomer, for example, allyl methacrylate, allyl acrylate, triallyl cyanurate, allyl cinnamate, allyl sorbate, diallyl maleate, diallyl phthalate, diallyl fumarate, ethylene glycol di (meth) acrylate. , Polyethylene glycol di (meth) acrylate, divinylbenzene,
1,3-butylene glycol di (meth) acrylate,
Examples include polyfunctional monomers such as divinylbenzene, which may be used alone or in combination of two or more.

The second layer is preferably a crosslinked rubber layer having a glass transition temperature of 0 ° C. or lower. When the glass transition temperature exceeds 0 ° C., the impact resistance of the transparent thermoplastic resin composition becomes insufficient, and when the second layer has a non-crosslinked structure, the impact strength becomes low and the transparent thermoplastic resin The transparency of the composition tends to deteriorate, and the heat resistance of the transparent thermoplastic resin composition tends to deteriorate. As the monomer forming the second layer, butyl acrylate as an acrylic acid alkyl ester, 2-ethylhexyl acrylate, benzyl acrylate,
A method in which styrene or benzyl methacrylate is appropriately selected and used in combination as the other monomer is particularly preferable. As the polyfunctional monomer forming the second layer, allyl methacrylate is particularly preferable, and 0.01 to 1% by weight of the second layer is preferably used.

In general, as components used in the rubber phase of the rubber-modified resin, conjugated dienes such as 1,3-butadiene and isoprene, n-butyl acrylate, and acrylic acid esters such as 2-ethylhexyl acrylate are mainly used. Used as an ingredient. However, while conjugated diene such as 1,3-butadiene and isoprene has an excellent function as rubber, it has a large coefficient of thermal expansion as compared with acrylate ester and the like, so that the temperature change amount of the refractive index is large. When the composition of the rubber phase or resin layer is improper and the difference between dnR / dT and dnP / dT is 0.00025 / K or more, the difference in the refractive index between the rubber phase and the resin layer at room temperature and during heating becomes too large. Therefore, when the haze at room temperature is small, the haze at the time of heating becomes high, and conversely, when the haze at the time of heating is small, the haze at the room temperature becomes high. Therefore, the value as a resin having transparency tends to be lost. Therefore, in the present invention, as a component used in the rubber phase, an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, 59.9.
.About.99.9% by weight, other copolymerizable monomers 0 to 40% by weight and polyfunctional monomers 0.05 to 5% by weight, provided that the above diene is added to the other copolymerizable monomers. It is desirable that the compound does not contain a system compound.

Examples of the monomer constituting the third layer of the core-shell type three-layer structure particles in the present invention include methacrylic acid such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, benzyl methacrylate and cyclohexyl methacrylate. Acrylic esters such as acid esters, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate and benzyl acrylate, aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene ,
N such as N-cyclohexylmaleimide, N-o-chlorophenylmaleimide, N-tert-butylmaleimide, etc.
-Substituted maleimide compounds, vinyl cyanide compounds such as acrylonitrile, methacrylonitrile and the like can be mentioned, and they can be used alone or in combination of two or more. If necessary, a chain transfer agent can be used. In that case, as the chain transfer agent, n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, s
It is preferable to use ec-butyl mercaptan or the like in an amount of 0.01 to 1% by weight of the third layer.

The third layer is preferably a non-crosslinked resin layer. When the third layer has a crosslinked structure, the dispersibility in the transparent thermoplastic resin becomes insufficient and the impact strength tends to decrease. Further, the refractive index of the third layer is preferably as close as possible to the refractive index of the transparent thermoplastic resin, and the third layer is preferably compatible with the transparent thermoplastic resin.

The core-shell type multilayer structure particles of the present invention are
It can be produced by a known emulsion polymerization method. As a manufacturing method, first, a desired monomer mixture is emulsion-polymerized to form core particles, and then another monomer mixture is emulsion-polymerized in the presence of the core particles to form a shell around it. Further, in the presence of the particles, another monomer mixture is emulsion polymerized to form another shell. Such reaction is repeated to obtain desired rubber layer-containing multi-layer structure particles. Suitable polymerization temperatures for forming the polymer or copolymer of each layer are 0 to 1 for each layer.
It is in the range of 20 ° C, preferably 5 to 90 ° C.

In the present invention, when the core-shell type multilayer structure particles are produced by emulsion polymerization, the first layer is polymerized when the dissolved oxygen concentration in the entire liquid phase of the polymerization system is 0.2 to 10 mg / liter. It is preferable to start. By this method, the haze due to heating is reduced, and it is not necessary to strictly carry out the nitrogen substitution of the polymerization system, so that the polymerization operation is simplified and the productivity is significantly improved, which is an unexpected effect.
When the dissolved oxygen concentration is less than 0.2 mg / liter, the effect of reducing haze due to heating is small, and when it exceeds 10 mg / liter, the polymerization rate may be reduced and the resin may be colored.

The type and amount of the emulsifier used in the emulsion polymerization are selected depending on the stability of the polymerization system, the particle size of the intended particles, and the like. Anionic surfactants, cationic surfactants and nonionic surfactants are used. Known emulsifiers such as the above are used alone or in combination of two or more kinds, and anionic surfactants are particularly preferably used. Examples of the anionic surfactant include carboxylates such as sodium stearate, sodium myristate, and sodium N-lauroyl sarcosinate, sulfonates such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate. Sulfate ester, mono-n-
Examples thereof include phosphate ester salts such as butylphenylpentaoxyethylene sodium phosphate. The emulsifier may be used in an amount of 0.01 to 15% by weight based on the resin.

The polymerization initiator used in emulsion polymerization is not particularly limited, but inorganic peroxides such as potassium persulfate and ammonium persulfate, hydrogen peroxide-ferrous iron salt system, potassium persulfate-sodium acid sulfite system. , Water-soluble redox initiators such as ammonium persulfate-sodium acid sulfite-based, water-oil redox initiators such as cumene hydroperoxide-sodium formaldehyde sulfoxylate-based, tert-butyl hydroperoxide-sodium formaldehyde sulfoxylate-based Initiators are used. Among these, inorganic peroxide-based initiators, water-soluble
An oil-soluble redox type initiator is preferably used.

In emulsion polymerization, a monomer, an emulsifier, an initiator, a chain transfer agent and the like may be added by any known method such as a batch addition method, a divided addition method and a continuous addition method. It is desirable to strictly determine the polymerization conditions such as the type and amount of the emulsifier and the initiator and the polymerization temperature so that the particle diameter falls within the predetermined range.

That is, the particle diameter (r) of the second layer is in the range of r (μm) = 0.05 to 0.30 (III), and r, the second layer in the first layer and the second layer.
Layer weight ratio (N) (second layer weight / (first layer weight + second layer
(Layer weight)) preferably has a relationship of N ≦ 0.1 / r-0.1 (IV).

When the particle diameter of the second layer is less than 0.05 μm, the haze during heating becomes very low, but the impact strength decreases, and when it exceeds 0.30 μm, the haze during heating increases. Become. The reason why the N value affects the haze during heating is as follows. That is, when the core-shell type multilayer structure particles are dispersed in the transparent thermoplastic resin, the third layer is compatibilized with and integrated with the transparent thermoplastic resin, so that the transparent thermoplastic resin is substantially First in the composition
The core-shell type multilayer structure particles are formed only by the layer and the second layer. Therefore, the present inventors
After considering the interaction only in the layers, it was found that the second layer, which is a cause of the haze during heating, has a lower weight ratio when heated as the weight ratio becomes smaller than that of the first layer. Therefore, when expressed by their weight ratio, the above formula (I
In the case of V), it was found that the temperature dependence of haze was suppressed.

The latex obtained by the emulsion polymerization method is
After adding other resin latices, stabilizers and the like as necessary, the polymer and the like can be taken out by a known method such as a spray drying method, an acid addition method, a salt addition method, and a freeze coagulation method. Among these, it is preferable to coagulate by a freeze coagulation method, which has the best optical properties. The coagulated polymer or the like is preferably dried after washing with water or warm water. The powder of the polymer or the like thus obtained is dried and then added with a transparent thermoplastic resin and, if necessary, known additives such as a stabilizer, a lubricant, a plasticizer, a filler, a dye and a pigment, and a Henschel mixer. It is possible to produce a transparent thermoplastic resin composition in which a rubber phase is dispersed in a transparent thermoplastic resin by a known method such as, for example, melting and kneading with an extruder after mixing with the above. The composition thus obtained can be shaped by a known method such as an extrusion molding method or an injection molding method.

[0032]

The present invention will be specifically described below with reference to examples. The measurements of various properties shown in the examples were carried out according to the following methods. In addition, parts represent parts by weight, and% represents% by weight. (1) Izod impact strength; ASTM-D256 (2) Total light transmittance, haze; ASTM-D1003 In the examples, the abbreviations in parentheses were used as follows. -Methyl methacrylate (MMA) -Methyl acrylate (MA) -Butyl acrylate (BA) -Styrene (ST) -Allyl methacrylate (ALMA) -Benzyl methacrylate (BZMA) -2-Ethylhexyl acrylate (2-EHA) ), 1,3-Butadiene (BD), n-octyl mercaptan (n-OM), sodium stearate (SS), sodium N-lauroyl sarcosinate (LSS), potassium persulfate (KPS)

Example 1 (Polymerization of the First Layer) 300 parts of ion-exchanged water, 1.0 part of SS and 0.1 part of LSS were put into a reaction vessel equipped with a reflux condenser, and the temperature was raised to 70 ° C. in an air atmosphere while stirring. Warmed and stirred for 30 minutes to dissolve the emulsifier. Then, after setting to a nitrogen atmosphere, 1.2 parts of a 5% KPS aqueous solution was immediately added, and M
A monomer mixture (1) consisting of 50 parts MA, 2 parts MA and 0.15 parts ALMA was continuously added. The water system and the monomer system immediately before the initiator was added are sampled, and the dissolved oxygen concentration is measured by a dissolved gas generator (DGA- manufactured by Gas Black Industrial Co., Ltd.).
MU type), the dissolved oxygen concentration in the aqueous system was 2.4 mg / liter, and the dissolved oxygen concentration in the monomer system was 32 mg / liter. Therefore, the dissolved oxygen concentration of the entire reaction system immediately before the start of polymerization is about 6.
It was 5 mg / liter. After the monomer system was charged, the temperature was raised to 80 ° C. and maintained for 60 minutes after passing the exothermic peak. (Polymerization of second layer) Then, in the presence of this latex, 5
% KPS aqueous solution 0.6 part, BA55. Department, ST
A monomer mixture (2) consisting of 12.6 parts and ALMA 1.6 parts was continuously added over 60 minutes, and after the addition was completed, 30
Hold for minutes. When this latex was diluted and observed with an electron microscope to measure the particle size, it was 0.14 μm, and there was almost no variation in particle size. The weight ratio of the rubber layer from the charged composition to the second layer was calculated to be 0.
Although it was 57, the upper limit of the weight ratio calculated from the particle diameter was 0.61, which was within the range. It should be noted that only the rubber layer was polymerized using this monomer mixture (2) at 23 ° C.
When the refractive index in was measured, nd = 1.4905
And the refractive index at 70 ° C. was measured to be nd
= 1.4783. Therefore, the temperature change amount of the refractive index of the rubber phase at 23 to 70 ° C. is dnR / dT = (1.490
5-1.4783) / (70-23) 〓0.00026
Met. (Polymerization of third layer) Then, in the presence of this latex, 5
% KPS aqueous solution 0.6 part, MMA 29 parts, MA
Monomer mixture (3) consisting of 1 part and n-OM 0.06 part
Was continuously added over 30 minutes, and after the addition was completed, the mixture was kept for 60 minutes to obtain a three-layer structure polymer latex.

The latex thus obtained was placed in a stainless steel container, frozen, and thawed at 70 ° C.
The polymer was separated by filtration. Furthermore, after washing with water at 70 ° C. and washing with water was repeated three times, the product was dried at 80 ° C. for 10 hours. The obtained acrylic multi-layer structure polymer (B) powder and acrylic resin (A) beads (Parapet HR-L; Kuraray Co., Ltd .; Tg = 102 ° C.) were mixed at a ratio of 2: 3 and pelletized. After pelletizing at 250 ° C. with an extruder (VSK type 40 m / m vent type extruder: manufactured by Chuo Kikai Seisakusho), molding temperature of 250 ° C., gold using an injection molding machine (N70A type injection molding machine: manufactured by Japan Steel Works) Predetermined test pieces were produced under the condition of the mold temperature of 50 ° C. and the physical properties were measured. After the first layer is polymerized,
The polymer obtained by polymerizing the third layer without polymerizing the second layer and acrylic resin beads were mixed at a ratio of 1.09: 3 (corresponding to the components of the test piece excluding the rubber layer). Similarly, after producing a rubber layer-free test piece, the refractive index at 23 ° C. was nd = 1.4896, and the refractive index at 70 ° C. was nd = 1.4856. Therefore, the temperature change amount of the refractive index of the resin phase from 23 to 70 ° C. is dnP / dT = (1.4896−1.4856) / (7
0-23) = 0.00009, dnR / dT-d
nP / dT was 0.00017. The results are shown in Table 1.

Example 2 BA5 was used as a monomer mixture used in the polymerization of the rubber layer.
Polymerization was carried out in the same manner as in Example 1 except that 4 parts, ST13.6 parts and ALMA 1.6 parts were used, and the physical properties were measured. Table 1 shows the evaluation results of the obtained test pieces. In addition,
Only the rubber layer was polymerized using this monomer mixture.
When the refractive index at 3 ° C. was measured, nd = 1.49
26, and the refractive index at 70 ° C. was measured,
It was nd = 1.4804.

Example 3 BA5 was used as a monomer mixture used in the polymerization of the rubber layer.
Polymerization was carried out in the same manner as in Example 1 except that 3 parts, ST14.6 parts and ALMA 1.6 parts were used, and the physical properties were measured. Table 1 shows the evaluation results of the obtained test pieces. In addition,
Only the rubber layer was polymerized using this monomer mixture.
When the refractive index at 3 ° C. was measured, nd = 1.49
47, and the refractive index at 70 ° C. was measured,
nd = 1.4825.

Example 4 In a reaction vessel equipped with a reflux condenser, 300 parts of ion-exchanged water and S
Add 1 part S, 0.1 part LSS, and raise the temperature to 70 ° C. in a nitrogen atmosphere while stirring at a rotation speed of 250 rpm to obtain 5% K.
3 parts of PS aqueous solution was added. Then MMA 144 parts, M
A monomer mixture consisting of 6 parts of A and 0.3 part of n-OM was added, the temperature was raised to 80 ° C. and held for 90 minutes to obtain an acrylic resin latex. Tg of acrylic resin contained in latex
Was 102 ° C. The obtained acrylic resin latex and the three-layer structure polymer latex obtained in Example 1 were mixed in 3 parts.
The mixture was mixed at a ratio of 2 and frozen, thawed, filtered, washed and dried in the same manner as in Example 1. The acrylic resin latex and the polymer obtained by polymerizing the first layer shown in Example 1 and then the third layer without polymerizing the second layer were 1.09: 3.
(Corresponding to the components of the test piece excluding the rubber layer) and the refractive index at 23 ° C. was measured.
It was 1.4893, and when the refractive index at 70 ° C. was measured, it was nd = 1.4852. The obtained powder was directly pelletized and injection-molded under the same conditions as in Example 1 to prepare a test piece, and its physical properties were measured. Table 1 shows the evaluation results of the obtained test pieces.

[0038]

[Table 1]

Example 5 2-E was used as a monomer mixture used in the polymerization of the rubber layer.
Polymerization was carried out in the same manner as in Example 1 except that 54 parts of HA, 13.6 parts of BZMA and 1.6 parts of ALMA were used, and the physical properties were measured. Table 2 shows the evaluation results of the obtained test pieces. The polymerization of the rubber layer was performed using this monomer mixture, and the refractive index at 23 ° C. was measured.
= 1.4915, and when the refractive index at 70 ° C. was measured, it was nd = 1.4793. Therefore dnR
/ DT-dnP / dT was 0.00017.

Example 6 MMA was used as a monomer mixture used in the polymerization of the first layer.
Using 46.8 parts, St5.2 parts, and 0.15 part of ALMA, B was used as a monomer mixture used in the polymerization of the second layer.
A49.5 parts, ST18.1 parts and ALMA 1.6 parts were used, and M was used as the monomer mixture used in the polymerization of the third layer.
Using 27 parts of MA, 3 parts of St, and 0.09 part of n-OM,
The same operation as in Example 1 was carried out to obtain an impact modified resin. Second
When the latex polymerized to the layer was diluted and observed with an electron microscope to measure the particle size, it was 0.15 μm, and there was almost no variation in particle size. In addition,
The dissolved oxygen concentration of the entire reaction system when the polymerization of the first layer was started was about 3.3 mg / l. Moreover, only the polymerization of the rubber layer was performed using the second layer monomer mixture, and the solid content in the latex was taken out and the refractive index at 23 ° C. was measured to find that nd = 1.5002 and the refractive index at 70 ° C. When the rate was measured, it was nd = 1.4880. Obtained powder and methyl methacrylate-styrene copolymer (MMA: ST = 90: 10; nd = 23 ° C. = 1.4
Nd at 998,70 ° C. = 1.4955; Tg = 105
℃) at a ratio of 1: 3, pellet extruder (VSK
Type 40 m / m vent type extruder: 2 by Chuo Kikai Seisakusho
After pelletizing at 40 ° C, an injection molding machine (N70A type injection molding machine: manufactured by Japan Steel Works) was used to manufacture predetermined test pieces under the conditions of a molding temperature of 240 ° C and a mold temperature of 50 ° C, and physical properties were measured. It was After the first layer was polymerized in the same manner as in Example 1, the polymer obtained by polymerizing the third layer without polymerizing the second layer and methyl methacrylate-styrene copolymer were added to 1.0.
When mixed at a ratio of 9: 3 (corresponding to the components excluding the rubber layer of the test piece) and the refractive index at 23 ° C. was measured, nd = 1.4993, and the refractive index at 70 ° C. was measured. , Nd = 1.4949. Therefore, dnR / dT-dnP / dT = 0.00017. Table 2 shows the evaluation results of the obtained test pieces.

Example 7 The operation during polymerization was carried out from the beginning under a nitrogen atmosphere, and the monomer system used was one which had been subjected to nitrogen bubbling for 3 minutes. At this time, the dissolved oxygen concentration in the aqueous system was 0.1 mg / liter, and the dissolved oxygen concentration in the monomer system was 1.4 mg / liter. Therefore, the dissolved oxygen concentration of the entire reaction system immediately before the initiation of polymerization was 0.3 mg / liter. Except for this, all operations were carried out in the same manner as in Example 1 to polymerize and measure the physical properties. Table 2 shows the evaluation results of the obtained test pieces.

Example 8 The operation during polymerization was carried out from the beginning in a nitrogen atmosphere, and the monomer system was also subjected to nitrogen bubbling to perform sufficient nitrogen substitution. At this time, the dissolved oxygen concentration in the aqueous system was 0.1 mg / liter, and the dissolved oxygen concentration in the monomer system was 0.1 mg / liter. Therefore, the dissolved oxygen concentration of the entire reaction system immediately before the initiation of polymerization was 0.1 mg / liter. Except for this, all operations were carried out in the same manner as in Example 1 to polymerize and measure the physical properties. Table 2 shows the evaluation results of the obtained test pieces.

[0043]

[Table 2]

Comparative Example 1 BA5 was used as a monomer mixture used in the polymerization of the rubber layer.
Polymerization was carried out in the same manner as in Example 1 except that 7 parts, ST10.6 parts and ALMA 1.6 parts were used, and the physical properties were measured. Table 3 shows the evaluation results of the obtained test pieces. In addition,
Only the rubber layer was polymerized using this monomer mixture.
When the refractive index at 3 ° C. was measured, nd = 1.48
79 and the refractive index at 70 ° C. was measured,
It was nd = 1.4757.

Comparative Example 2 BA5 was used as a monomer mixture used in the polymerization of the rubber layer.
Polymerization was carried out in the same manner as in Example 1 except that 8.0 parts, ST 9.6 parts and ALMA 1.6 parts were used, and the polymerization was carried out to measure the physical properties. Table 3 shows the evaluation results of the obtained test pieces. It should be noted that when only the rubber layer was polymerized using this monomer mixture and the refractive index at 23 ° C. was measured, nd =
It was 1.4859, and when the refractive index at 70 ° C. was measured, it was nd = 1.4738.

Comparative Example 3 BA4 was used as a monomer mixture used in the polymerization of the rubber layer.
Polymerization was carried out in the same manner as in Example 1 except that 9.5 parts, ST18.1 parts, and ALMA 1.6 parts were used, and the physical properties were measured. Table 3 shows the evaluation results of the obtained test pieces. It should be noted that when only the rubber layer was polymerized using this monomer mixture and the refractive index at 23 ° C. was measured, nd =
It was 1.4999, and when the refractive index at 70 ° C. was measured, it was nd = 1.4877.

Comparative Example 4 BA4 was used as the monomer mixture used in the polymerization of the rubber layer.
0.6 parts, BD 27.0 parts, cumene hydroperoxide 0.07 parts, Rongalit 0.5 parts, ferrous sulfate 0.01 parts as an initiator system for the rubber layer, and 55 ° C. in an autoclave. Polymerization was performed in the same manner as in Example 1 except that the polymerization was performed for 6 hours, and the physical properties were measured. Table 4 shows the evaluation results of the obtained test pieces. After only polymerizing the rubber layer using this monomer mixture, the solid content in the latex was taken out and the refractive index at 23 ° C. was measured to find that nd = 1.4908 and the refractive index at 70 ° C. When the rate was measured, it was nd = 1.4612. Therefore, dnR / dT-dnP / dT is 0.0005.
It was 4.

[0048]

[Table 3]

[0049]

According to the transparent thermoplastic resin composition of the present invention, the impact resistance and molding processability of the conventional rubber-modified transparent thermoplastic resin are maintained, and the haze and the transparency are decreased by heating. It is possible to provide a transparent thermoplastic resin composition having improved drawbacks such as the above.

Claims (4)

[Claims] 1. A transparent thermoplastic resin composition in which core-shell type multilayer structure particles having a rubber phase having a glass transition temperature of 0 ° C. or less are dispersed in a transparent thermoplastic resin, each of which is measured independently. The refractive index (nR23) of the rubber phase and the refractive index (nP23) of the resin phase at 23 ° C. at this time are in the relationship of the following formula (I), and of the rubber phase at 23 to 70 ° C. when measured individually. Refractive index temperature change (dnR / dT) and resin phase refractive index temperature change (dn
P / dT) has the relationship of the following formula (II), The transparent thermoplastic resin composition characterized by the above-mentioned. 0.01>nR23-nP23> 0 (I) 0.00025> | dnR / dT-dnP / dT | (II) 2. The rubber phase has an alkyl group having 1 to 8 carbon atoms.
Acrylic acid alkyl ester 59.9 to 99.9
%, Other copolymerizable monomers 0 to 40% by weight and polyfunctional monomers 0.05 to 5% by weight, other copolymerizable monomers not containing conjugated diene compounds The transparent thermoplastic resin composition according to claim 1, wherein 3. The core-shell type multi-layer structure particles, wherein the concentration of dissolved oxygen in the entire liquid phase of the polymerization system is 0.2 in the emulsion polymerization method.
It is obtained by initiating the polymerization of the first layer at 10 to 10 mg / liter, 3.
The transparent thermoplastic resin composition described in 1. 4. The transparent thermoplastic resin is a transparent thermoplastic resin having a glass transition temperature of 50 ° C. or higher, and the core-shell type multilayer structure particles have a glass transition temperature of 50 ° C. in the first layer.
The resin layer, the second layer is a crosslinked rubber layer, and the third layer is a non-crosslinked resin layer compatible with the transparent thermoplastic resin.
Further, the particle diameter (r) of the second layer is within the range of the following formula (III), and the weight ratio (N) of the second layer in the first layer and the second layer (N) (second layer weight / (second layer (1 layer weight + 2nd layer weight)) has the relationship of the following formula (IV), The transparent thermoplastic resin composition of any one of Claims 1-3 characterized by the above-mentioned. r (μm) = 0.05 to 0.30 (III) N ≦ 0.1 / r-0.1 (IV)