JPH1149922A - Acrylic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide acrylic resin compositions having very small variations in optical characteristics by change in temperature and improved solvent resistance without adversely affecting clarity and flowability. SOLUTION: Acrylic resin compositions comprise (A) 20-96 pts.wt. thermoplastic acrylic resin comprising 80-100 wt.% methyl methacrylate and 0-20 wt.% another monomer copolymerizable therewith and (B) 4-80 pts.wt. rubber- containing acrylic multistage process polymer to be obtained by emulsion polymerization. In this case, the acrylic resin composition has a continuous two-phase (i.e., matrix and dispersed phase) structure when its ultrathin section dyed with ruthenium tetraoxide is observed by a transmission electron microscope and the matrix is undyed continuous portions and the dispersed phase is incontinuous phase portions composed of dyed portions and undyded portions and mainly the dispersed phase incontinuously surrounds the periphery of the undyed circular portion with dyed portions in the form of particulate matters and the dyed portions are micro-dispersed in the undyed circular portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic resin composition. The present invention relates to an acrylic resin composition having improved solvent resistance without impairing properties.

[0002]

2. Description of the Related Art As a method for improving the solvent resistance of an acrylic resin, a method of increasing the molecular weight of the acrylic resin itself, a method of incorporating a multilayer structure polymer in which a soft layer having a crosslinked structure and a hard layer are incorporated, and the like. Has been proposed. However, in the method of increasing the molecular weight of the acrylic resin itself, it is necessary to greatly increase the molecular weight in order to obtain a substantial effect, so that the flowability of the polymer decreases and moldability deteriorates. There is a problem,
There is also a problem that the solvent resistance is significantly reduced in an environment where a certain amount of deformation is given.

On the other hand, in the method of incorporating a multi-layered polymer, although the effect is recognized even in an environment where a certain amount of deformation is given, the optical characteristics greatly fluctuate due to a change in temperature, and an acrylic resin having solvent resistance is used. There were problems such as the limited range of application. In order to improve this problem, a method of reducing a change in optical characteristics due to a temperature change by increasing a graft ratio between a resin component and an elastomer component has been studied (see Japanese Patent Application Laid-Open No. 63-199258). In fact, none of the polymers obtained by these methods have physical properties sufficient for practical use. Also, a method of reducing the particle size of the multilayer structure polymer is being studied (Japanese Patent Publication No. Sho 5
No. 9-10745). However, in this method, since the particle size of the multilayer structure polymer needs to be 0.02 to 0.09 μm, the fluctuation of the optical characteristics due to the temperature change is small, but a large amount of an emulsifier is required at the time of polymerization. There are problems such as an increase in manufacturing cost, deterioration in color tone and transparency of the acrylic resin, and an increase in viscosity during polymerization, resulting in deterioration in productivity.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the solvent resistance of an acrylic resin without deteriorating the inherent properties of the acrylic resin such as transparency and fluidity, by minimizing fluctuations in optical characteristics due to temperature changes. To provide an acrylic resin composition.

[0005]

Means for Solving the Problems The present inventors have made intensive studies in view of such a situation, and as a result, the above problems can be solved by dispersing a rubber-containing acrylic multi-stage polymer in a specific state. This led to the completion of the present invention.

That is, the gist of the present invention is as follows.
(A) 20 to 96 parts by weight of a thermoplastic acrylic resin comprising 80 to 100% by weight of methyl methacrylate and 0 to 20% by weight of another monomer copolymerizable therewith, and (B) a rubber obtained by emulsion polymerization Containing acrylic multi-stage polymer 80
~ 4 parts by weight of the resin composition, when observed with a transmission electron microscope ultra-thin sections of the resin composition stained with ruthenium tetroxide, the resin composition has a sea-island structure The sea portion is a continuous phase portion that is not stained with ruthenium tetroxide, and the island portion is a discontinuous phase portion that is composed of a stained portion and a portion that is not stained, and the island portion is mainly stained with ruthenium tetroxide. The outer part of the circular part that is not dyed is intermittently surrounded by ruthenium tetroxide as a plurality of particles, and the part that is dyed with ruthenium tetroxide is micro-dispersed in the circular part that is not dyed. This is an acrylic resin composition characterized by having a structure having

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The thermoplastic acrylic resin (A) used in the present invention comprises 80 to 100% by weight of methyl methacrylate and 0 to 20% by weight of another monomer copolymerizable therewith. It is a thermoplastic polymer obtained by polymerization. Other monomers copolymerizable with methyl methacrylate are not particularly limited, and include, for example, methacrylic esters other than methyl methacrylate such as ethyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate; methyl acrylate, acrylic Acrylic esters such as ethyl acrylate; aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene; N-cyclohexylmaleimide, No-chlorophenylmaleimide, Nt
N-substituted maleimide compounds such as tert-butylmaleimide; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; and the like, used alone or in combination of two or more. The proportion of the other monomer copolymerizable with methyl methacrylate is 0 to 20% by weight, preferably 0.5 to 15% by weight.

The thermoplastic acrylic resin (A) is obtained by a known method such as suspension polymerization, solution polymerization, emulsion polymerization, bulk polymerization, etc., and is obtained by two or more different compositions or by different production methods. May be used in combination.
Also, as the thermoplastic acrylic resin (A), a commercially available acrylic resin for molding can be used. The thermoplastic acrylic resin (A) can be polymerized using a chain transfer agent such as mercaptan in order to improve molding processability, and its weight average molecular weight is usually 30,000 to 200,000, preferably 40 to 200,000.
It is preferable to adjust to a range of 160,000.

The rubber-containing acrylic multi-stage polymer (B) used in the present invention is obtained by emulsion polymerization and is mixed and kneaded with the thermoplastic acrylic resin (A) to obtain a dispersion state described later. If it is, there is no particular limitation.
As a method for producing the rubber-containing acrylic multi-stage polymer (B), for example, first, after a first-stage monomer mixture is emulsion-polymerized to obtain core particles (corresponding to the first-stage polymer), Emulsion polymerization of the next stage monomer mixture in the presence of the core particles, and further emulsion polymerization of another monomer mixture in the presence of the core and shell particles to form another shell, etc. Thus, a desired multi-stage polymer can be obtained by repeating the polymerization. The polymerization temperature for forming the polymer or copolymer of each layer is usually 5 to 120 for each layer.
° C, preferably in the range of 40 to 90 ° C.

The type and amount of the emulsifier used in the emulsion polymerization are usually selected depending on the stability of the polymerization system, the desired average particle size, etc., but anionic surfactants, cationic surfactants, nonionic surfactants And other known emulsifiers can be used alone or in combination of two or more. Of these, preferred emulsifiers are anionic surfactants. Examples of the anionic surfactant include carboxylate salts such as sodium stearate, sodium myristate, and sodium N-lauroyl sarcosinate; sulfonates such as sodium dioctyl sulfosuccinate and sodium dodecyl benzene sulfonate; dodecyl diphenyl ether disulfonic acid Disulfonates such as sodium; sulfates such as sodium lauryl sulfate; phosphates such as mono-n-butylphenylpentaoxyethylene sodium phosphate.

The polymerization initiator used in the emulsion polymerization is not particularly limited, and examples thereof include inorganic peroxides such as potassium persulfate and ammonium persulfate; hydrogen peroxide-ferrous salt, potassium persulfate-sodium acid sulfite; Water-soluble redox initiators such as ammonium persulfate-sodium acid sulfite; water-soluble redox initiators such as cumene hydroperoxide-sodium formaldehyde sulfoxylate and tert-butyl hydroperoxide-sodium formaldehyde sulfoxylate; Are used.

As the chain transfer agent, for example, n-octyl mercaptan, n-dodecyl mercaptan, ter
t-Dodecyl mercaptan, sec-butyl mercaptan and the like are used as needed. In emulsion polymerization, a monomer, an emulsifier, an initiator, a chain transfer agent, and the like are added all at once,
It can be added by any known method such as a split addition method and a continuous addition method.

The rubber-containing acrylic multi-stage polymer (B) in the present invention is preferably (1) a monomer mixture mainly composed of methyl methacrylate as the first stage, (2)
As the second step, a monomer mixture mainly composed of butyl acrylate as a rubber component, and (3) as the third step, a monomer mixture mainly composed of methyl methacrylate obtained by polymerization are exemplified.

The first stage polymer in the rubber-containing acrylic multi-stage polymer of the preferred embodiment is, for example, 80 to 99.99% by weight of methyl methacrylate, 0.01 to 0. It is obtained by emulsion polymerization of a monomer mixture consisting of 5% by weight and 0 to 19.99% by weight of other monomers copolymerizable therewith. As the graft-linking monomer, an allyl ester of an α, β-unsaturated carboxylic acid copolymerizable with methyl methacrylate is preferable, for example, allyl methacrylate, allyl acrylate, allyl cinnamate, allyl sorbate and the like. No. These can be used alone or in combination of two or more. These graft-linking monomers are usually 0.01 to
It is used in the range of 0.5% by weight.

Examples of other monomers copolymerizable with methyl methacrylate and the graft-linking monomer include ethyl methacrylate, cyclohexyl methacrylate, and the like.
Methacrylates other than methyl methacrylate such as benzyl methacrylate; acrylates such as methyl acrylate and ethyl acrylate; aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene;
N-substituted maleimide compounds such as cyclohexylmaleimide, No-chlorophenylmaleimide, and N-tert-butylmaleimide; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; these may be used alone or in combination of two or more. These monomers have 0
To 19.99% by weight, preferably 0 to 15% by weight. The proportion of the first-stage polymer in the rubber-containing acrylic multistage polymer is 30 to 70% by weight, preferably 35 to 70% by weight.
６０60% by weight.

The copolymer composition in the first stage excluding the graft-linking monomer is similar to the copolymer composition of the thermoplastic acrylic resin (A). It is preferable from the necessity. Also,
As long as the monomers constituting the first-stage polymer and the composition ratio are within the ranges described above, it is possible to further divide the first stage or to change the composition ratio and type of the monomers. is there.

Next, the second stage of the rubber-containing acrylic multi-stage polymer is, for example, 70 to 89% by weight, preferably 76 to 8% by weight of n-butyl acrylate in the presence of the first stage polymer.
7% by weight, 10 to 29% by weight of styrene, preferably 12%
-23% by weight and graft-linking monomer 1-5% by weight
Obtained by polymerizing a monomer mixture consisting of As the graft-linking monomer, those mentioned in the first stage can be used. The proportion of the second stage in the rubber-containing acrylic multi-stage polymer is 10 from the viewpoint of balance for effectively reducing strain generated due to stress and the like and reducing temperature dependence of optical properties such as haze. -40% by weight, preferably 15-35% by weight. Tg of second stage polymer
Is 25 to effectively reduce the strain generated by stress and the like.
C. or lower, more preferably 0.degree. C. or lower. Further, if the monomers constituting the second-stage polymer and the composition ratio are within the ranges described above, the second stage may be further divided, or the composition ratio and type of the monomers may be changed. It is possible. The average particle diameter of the particles obtained by the second-stage polymerization is preferably 50 to 300 nm.

Further, the third stage in the rubber-containing acrylic multi-stage polymer is prepared by mixing 80 to 100% by weight of methyl methacrylate and copolymerizing with methyl methacrylate in the presence of the polymer obtained in the first stage and the second stage. It contains the polymer obtained in the first and second stages obtained by polymerizing a monomer mixture consisting of 0 to 20% by weight of other possible monomers. As other monomers copolymerizable with methyl methacrylate, those mentioned in the first stage can be used. In the third stage, when the rubber-containing acrylic multi-stage polymer and the thermoplastic acrylic resin are heated and melt-mixed, it is preferable to adjust the molecular weight with a chain transfer agent as necessary in order to improve the fluidity. The proportion of the third stage in the rubber-containing acrylic multi-stage polymer is preferably 5 to 50% by weight, in order to obtain good dispersibility during melt-kneading and to make the ratio of the second stage an appropriate range. Is 15 to 35% by weight. The Tg of the third-stage polymer is preferably 50 ° C. or higher in order to obtain good heat resistance of the molded product. further,
If the monomers constituting the third stage and the composition ratio are within the ranges described above, the third stage may be further divided or the composition ratios and types of the monomers and chain transfer agents may be changed. It is also possible to make it.

The emulsion containing the rubber-containing acrylic multi-stage polymer (B) produced by the emulsion polymerization method is prepared by adding, for example, an emulsion containing a thermoplastic acrylic resin (A), a stabilizer, and the like, and then spray-drying the mixture. Solid matter is separated by a known method such as an addition method, a salt addition method, and a freeze-coagulation method. The separated solid is washed with water or warm water, and then dried to form a powder.

The acrylic resin composition of the present invention contains 20 to 96 parts by weight, preferably 4 parts by weight, of the thermoplastic acrylic resin (A).
It must be composed of 0 to 90 parts by weight and 80 to 4 parts by weight, preferably 60 to 10 parts by weight of the rubber-containing acrylic multi-stage polymer (B). When the amount of the rubber-containing acrylic multi-stage polymer (B) is less than 4 parts by weight, the solvent resistance of the acrylic resin composition is insufficient. On the other hand, when it exceeds 80 parts by weight, the color tone and the melt processability are poor. It is not preferable because sufficient one cannot be obtained.

Further, in the acrylic resin composition of the present invention, when an ultrathin section of the resin composition stained with ruthenium tetroxide is observed using a transmission electron microscope, the resin composition has a sea-island structure. The sea portion is a continuous phase portion that is not stained with ruthenium tetroxide, and the island portion is a discontinuous phase portion that is composed of a stained portion and a non-stained portion, and the island portion is mainly made of ruthenium tetroxide. A part (stained part b) dyed with ruthenium tetroxide intermittently surrounds an outer part of a circular part (unstained part a) which is not dyed as a plurality of particulates, and the inside of the non-stained part a It is necessary that the portion dyed with ruthenium tetroxide (stained portion c) has a micro-dispersed structure. In order to satisfy this requirement, the rubber-containing acrylic multi-stage polymer (B) of the present invention has a weight ratio of the first stage polymer to the second stage polymer of the first stage polymer / second polymer. It is necessary that the stage polymer> 1 and preferably the first stage polymer / the second stage polymer> 1.25. When the amount of the second-stage polymer with respect to the first-stage polymer is too large, the range in which the dyed portion b generated by the second-stage polymerization surrounds the outer periphery of the non-dyeed portion a increases, and the dyed portion Since the size per particle of b becomes large or the dyed parts b are connected to each other, the dyed part b becomes large and the non-dyed part a is completely taken in, which is not preferable. It is not preferable that the second stage surrounds the first stage in a layered manner because the optical properties of the acrylic resin composition greatly fluctuate due to a temperature change.

The average particle size per particle of the dyed portion b of the acrylic resin composition is 50 nm or less, preferably 5 to 50 nm, more preferably 7 to 40 nm. The average particle diameter per particle of the dyed portion b can be measured by observing an ultrathin section of the acrylic resin composition stained with ruthenium tetroxide using a transmission electron microscope, A micrograph is taken and the particle size is measured using the photograph. At this time, of the structure of the rubber-containing acrylic multi-stage polymer (B), the structure in which the second stage polymer surrounds the outside of the first stage is a layered structure, and the so-called second stage polymer is a core-shell shape. Instead of a structure covering the first stage polymer, the second stage covers the outside of the first stage with a normal diameter of 50 mm.
It is necessary to have a structure in which the non-stained portion a is intermittently divided into particles (stained portions b) having a size of nm or less. The average particle diameter per particle in the dyed portion b means the particle diameter per divided particle.

The acrylic resin composition is prepared by adding a thermoplastic acrylic resin (A) and a rubber-containing acrylic multi-stage polymer (B) to a stabilizer, a lubricant, a plasticizer, a filler, a dye, a pigment and the like, if necessary. It can be produced by adding a known additive and mixing or kneading by a known method.

The acrylic resin composition thus obtained can be used to obtain molded articles such as films, sheets, molded articles and the like by known methods such as extrusion molding and injection molding. In these compacts, the flexural modulus is 15
It is desirable that it is 000 kg / cm ^{2 to} 32000 kg / cm ² .

[0026]

The present invention will now be described more specifically with reference to examples. In the examples, “part” and “%” are
"Parts by weight" and "% by weight" are shown, respectively. The measurements and evaluations shown in the examples were performed according to the following methods.
Total light transmittance, haze: 23 ° C. and 7 ° C. using a 3.2 mm thick test piece according to ASTM-D1003.
The optical properties at 0 ° C. were measured.

Average particle diameter: A latex of the rubber-containing acrylic multi-stage polymer (B) is sampled during or after the polymerization, diluted with water to a solid content of 0.05%, and analyzed using a spectrophotometer. The absorbance at a wavelength of 500 nm was measured. The average particle diameter in the latex was determined using this value and a calibration curve prepared by measuring absorbance in the same manner for a sample in which the latex particle diameter was measured from a transmission electron micrograph.

Observation with an electron microscope photograph: The obtained resin composition test piece was cooled to -135 ° C and cut into a thickness of 0.1 µm or less. The section was stained in ruthenium tetroxide vapor for 15 minutes to prepare a sample, and a photograph was taken with a transmission electron microscope (device used: Hitachi transmission electron microscope H-7100FA). Using this photograph, 50 particle diameters of the dyed portion b were measured, and the average value thereof was obtained as the average particle size of the dyed portion b.

Flexural modulus was measured according to ASTM-D790.

Solvent resistance: A jig having a curved surface having the same curvature as an arbitrary elliptic curve was prepared, and a deformation amount of 0.7% strain was applied to the test piece from the curved surface portion and the thickness of the test piece. The test piece was fixed at the given position, isopropyl alcohol was applied, and the time until cracks were generated was measured.

The abbreviations used in the examples are shown below. Methyl methacrylate (MMA), methyl acrylate (MA), n-butyl acrylate (BA), styrene (St), allyl methacrylate (ALMA), n-octyl mercaptan (n-OM), N-lauroyl sarcosine Sodium (LSS), potassium persulfate (KP
S)

Example 1 (First-stage polymerization) In a 75-liter reaction vessel equipped with a reflux condenser, 32400 g of ion-exchanged water and 172.8 g of LSS were added.
And heated to 70 ° C. in a nitrogen atmosphere while stirring at a rotation speed of 70 rpm.
A monomer mixture consisting of 10 g and 8.73 g of ALMA (hereinafter referred to as M1-1) was charged, and then KPS
2.91 g was charged and held for 10 minutes. Next, KPS
After charging 6.8 g, MMA 6600 g, MA 200 g,
A monomer mixture consisting of 20.4 g of ALMA (hereinafter referred to as M1-2) was continuously added over 50 minutes, and the mixture was kept for 30 minutes after completion of the addition to obtain a latex. (Second stage polymerization) In the presence of this latex, KPS
After charging 3.15 g, BA5150 g, St1150
g, and a monomer mixture consisting of 189 g of ALMA (hereinafter referred to as M2) was continuously added over 120 minutes, and the mixture was kept for 180 minutes after the completion of the addition. (Third Stage Polymerization) In the presence of the latex obtained after the completion of the second stage, 5.6 g of KPS was added, and then MMA550 was added.
A monomer mixture consisting of 0 g, 100 g of MA and 16.8 g of n-OM (hereinafter referred to as M3) was continuously added over 30 minutes, and after completion of the addition, the mixture was maintained for 60 minutes to obtain a three-stage polymer latex. Was. The average particle diameter of the latex obtained by sampling during and at the end of the polymerization was determined to be 94 nm for the first stage, 102 nm for the second stage, and 110 nm for the third stage. Was.

The thus obtained three-stage polymer latex was placed in a stainless steel container, frozen in a freezer at −30 ° C., thawed at 70 ° C., and filtered to separate a polymer. Further, washing and dehydration were repeated three times with warm water at 70 ° C., followed by drying at 80 ° C. for 20 hours. The obtained three-stage polymer powder and thermoplastic acrylic resin pellets (copolymer of 98% by weight of methyl methacrylate and 2% by weight of methyl acrylate, weight average molecular weight 110,000) are in a ratio of 1: 1. After mixing and pelletizing at 250 ° C. with a pellet extruder (VSK type 40 m / m vent type extruder: manufactured by Chuo Kikai Seisakusho), the molding temperature is determined using an injection molding machine (N70A type injection molding machine: manufactured by Nippon Steel Works). A predetermined test piece was prepared under the conditions of 250 ° C. and a mold temperature of 50 ° C., and physical properties were measured. Table 1 shows the evaluation results of the obtained test pieces.

Using the test piece obtained here, the shape of the stained part was observed and measured by an electron micrograph, and the outer periphery of the circular part (unstained part a) not stained with ruthenium tetroxide was treated with tetroxide. The part stained with ruthenium (stained part b) is intermittently surrounded by a plurality of particles, and the part stained with ruthenium tetroxide (stained part c) is micro-dispersed in the unstained part a. I was In addition, the average particle size per particle of the dyed portion b was 25 nm. FIG. 1 is a schematic view of the island structure of the resin composition based on the electron micrograph at this time.

Examples 2 to 4 Using the powder of the three-stage polymer obtained in Example 1, a test piece was prepared in the same manner as in Example 1 except that the mixing ratio with the thermoplastic acrylic resin was changed. Except for this, evaluation was performed by operating in the same manner as in Example 1. Table 1 shows the results.

Example 5 In Example 1, the amount of the emulsifier used was changed to LSS12.
The operation was evaluated in exactly the same manner as in Example 1 except that the amount was changed to 9.6 g. Table 1 shows the results. When the average particle diameter was measured using the latex polymerized to the second stage in the same manner as in Example 1, it was 126 nm. Using a test piece prepared in the same manner as in Example 1, the shape of the stained portion was observed and measured by an electron micrograph. The situation was the same as in Example 1, and the per-particle content of the stained portion was one. The average particle size was 19 nm.

Examples 6 to 8 Using the powder of the multi-stage polymer obtained in Example 5, test pieces were prepared by changing the mixing ratio with the thermoplastic acrylic resin as in Example 1. Except for this, the operation was performed in the same manner as in Example 5, and the evaluation was performed. Table 1 shows the results.

Example 9 In Example 1, (M1-1) was replaced with 2550 g of MMA,
MA 50g, ALMA 7.8g, (M1-2) MMA
10100 g, MA 250 g, ALMA 31.05 g,
(M-2) BA3550g, St770g, ALMA
129.6 g, (M3) MMA 4200 g, MA12
0 g and the composition of n-OM 12.96 g, and KPS was added to each polymerization initiator at the time of polymerization of (M1-1) to 2.6.
g, 10.35 g for the polymerization of (M1-2), 2.16 g for the polymerization of (M2), and 4.32 g for the polymerization of (M3). Was evaluated. Table 1 shows the obtained results. When the average particle diameter was measured using the latex polymerized to the second stage in the same manner as in Example 1, it was 103 nm. Using a test piece prepared in the same manner as in Example 1, the shape of the stained portion was observed and measured by an electron micrograph. The situation was the same as in Example 1, and the per-particle content of the stained portion was one. The average particle size was 22 nm.

Examples 10 to 12 Using the multistage polymer powder obtained in Example 9 and changing the blending ratio with the thermoplastic acrylic resin as in Example 1, a test was conducted in the same manner as in Example 1. Pieces were made. Except for this, operation was performed in the same manner as in Example 9 to evaluate the results. Table 1 shows the results.
Shown in

Example 13 A reaction vessel equipped with a 75-liter reflux condenser was charged with 32400 g of ion-exchanged water and 86.4 g of LSS, and was charged at 70 rpm.
After the temperature was raised to 70 ° C. under a nitrogen atmosphere while stirring at a rotation speed of MMA, 21168 g of MA, 432 g of MA, n-OM5
Of the 4 g of the monomer mixture, 2160 g were charged, and then 2.16 g of KPS were charged and held for 20 minutes. Next, after adding 8.64 g of KPS, 8640 g of the monomer mixture was continuously added over 40 minutes, and held for 60 minutes after the addition was completed. Further, 10.8 g of KPS was added, and the remaining 10854 g of the monomer mixture was continuously added over 50 minutes. After the completion of the addition, the mixture was kept for 1 hour to obtain a thermoplastic acrylic resin emulsion. The obtained thermoplastic acrylic resin emulsion and the three-stage polymer latex obtained in Example 1 were mixed at a ratio of 1: 1.
In the same manner as described above, freezing, thawing, filtration, washing and drying were performed. The obtained powder and the same thermoplastic acrylic resin as in Example 1 were mixed at a ratio of 1 to 1, and a test piece was prepared by pelletization and injection molding under the same conditions as in Example 1 to measure physical properties. Was done. Table 2 shows the evaluation results of the obtained test pieces.

COMPARATIVE EXAMPLE 1 In the first-stage polymerization, 32400 g of ion-exchanged water, 10.8 g of LSS and 86.4 g of sodium stearate were charged into a reaction vessel equipped with a 75-liter reflux condenser, and 70 rpm.
After the temperature was raised to 70 ° C. under a nitrogen atmosphere while stirring at a rotation speed of 7,878 g of MMA, 378 g of MA, and ALMA1
A monomer mixture consisting of 8.9 g was charged. Then KP
S7.56 g was added, and after the generation of an exothermic peak due to the polymerization, polymerization was carried out at 80 ° C. for 30 minutes.
194.4 g, and the composition and amount of (M3) were changed to MMA4
Change to 104g, MA216g, n-OM 8.64g,
Latex and powder of a three-stage polymer were prepared in the same manner as in Example 1 except that KPS was used as the polymerization initiator in the same manner as in Example 1 except that 9.72 g was used for the polymerization of (M2) and 4.32 g was used for the polymerization of (M3). The body was obtained and evaluated. Table 3 shows the evaluation results. When the average particle diameter was measured using the latex polymerized to the second stage in the same manner as in Example 1, it was 223 nm. Using a test piece prepared in the same manner as in Example 1, the diameter of the stained portion b was measured by an electron micrograph. Met. FIG. 2 is a schematic view of the island structure of the resin composition based on the electron micrograph at this time.

Comparative Examples 2 to 4 Test pieces were prepared in the same manner as in Example 1 except that the mixing ratio with the thermoplastic acrylic resin (A) was changed using the multi-stage polymer powder obtained in Comparative Example 1. did. Other than this, Example 1
The operation was performed in the same manner as described above. Table 3 shows the results.

Comparative Example 5 (First Stage Polymerization) In a 75 liter reaction vessel equipped with a reflux condenser, 32400 g of ion-exchanged water and 453.6 g of LSS were added.
And heated to 70 ° C. under a nitrogen atmosphere while stirring at a rotation speed of 70 rpm, and then BA5346 g, St11
A monomer mixture consisting of 34 g and 97.2 g of ALMA was charged, and then 6.48 g of KPS was charged and maintained for 60 minutes. Next, 6.48 g of KPS was charged and BA5346 was added.
g, St1134 g, and ALMA 97.2 g were continuously added over 60 minutes.
It was held for 0 minutes to obtain a latex. (Second stage polymerization) In the presence of the latex, KPS
8.64 g was charged, and MMA8121.6 g, MA51
A monomer mixture consisting of 8.4 g and 25.92 g of n-OM was continuously added over 60 minutes, and after completion of the addition, the mixture was maintained for 60 minutes to obtain a two-stage polymer latex. When the average particle size of the latex obtained by sampling during and after the polymerization was determined, the first stage as the innermost soft layer was 69 nm, and the second stage as the outermost hard layer was 81 nm. . The latex thus obtained was put in a stainless steel container, frozen in a freezer at -30 ° C, and
After melting, the polymer was separated by filtration. 7 more
After repeating washing and dehydration three times with hot water at 0 ° C.,
Dried for hours. The obtained rubber-containing acrylic multi-stage polymer powder and the same thermoplastic acrylic resin as in Example 1 were mixed at a ratio of 1: 1, and a pellet extruder (VSK type 4) was used.
0m / m vent type extruder: manufactured by Chuo Kikai Seisakusho)
After pelletization at ℃, a predetermined test piece was prepared using an injection molding machine (N70A type injection molding machine: manufactured by Nippon Steel Works) at a molding temperature of 250 ° C and a mold temperature of 50 ° C, and physical properties were measured. . Table 3 shows the evaluation results of the obtained test pieces. Using the test piece obtained here, the shape of the stained part was observed and measured by an electron micrograph, and only the first-stage elliptical particles were observed, and the average particles in the almost uniformly dyed part were observed. The diameter was 70 nm.

Comparative Examples 6 to 8 Using the two-stage polymer powder obtained in Comparative Example 5, test pieces were prepared by changing the blending ratio with the thermoplastic acrylic resin as in Example 1. Except for this, operation was performed in the same manner as in Comparative Example 5, and the evaluation was performed. Table 3 shows the results.

Comparative Example 9 A test piece was prepared using only the same thermoplastic acrylic resin as in Example 1 without using any multi-stage polymer, and evaluated. Table 4 shows the results.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

According to the present invention, the optical properties, mechanical properties and moldability of conventional acrylic resins are maintained, and solvent resistance, especially in an environment where a certain strain is applied. Can provide an improved acrylic resin composition.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an island structure of a dyed resin composition according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an island structure of a dyed resin composition in Comparative Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI (C08F 285/00 220: 10 212: 08 220: 14)

Claims (3)

[Claims] (A) Methyl methacrylate 80-100
20 to 96 parts by weight of a thermoplastic acrylic resin composed of 0 to 20% by weight and another monomer copolymerizable therewith, and (B) a rubber-containing acrylic multi-stage polymer 80 to 80 obtained by emulsion polymerization. A resin composition consisting of 4 parts by weight, and when the ultrathin section of the resin composition stained with ruthenium tetroxide is observed using a transmission electron microscope, the resin composition has a sea-island structure. The sea portion is a continuous phase portion that is not stained with ruthenium tetroxide, and the island portion is a discontinuous phase portion that is composed of a stained portion and a non-stained portion, and mainly the island portion is not stained with ruthenium tetroxide. The part that is stained with ruthenium tetroxide intermittently surrounds the outer periphery of the circular part as a plurality of particulates, and the part that is stained with ruthenium tetroxide is a micro part in a circular part that is not stained. Acrylic resin composition which is a to that structure. 2. A rubber-containing acrylic multi-stage polymer (B)
But (1) methyl methacrylate 80 to 9 as the innermost layer
9.99% by weight, graft-linking monomer 0.01 to 0.1%
5% by weight and other monomers 0 to 1 copolymerizable therewith
1st stage obtained by polymerizing a monomer mixture consisting of 9.99% by weight; (2) 70-89% by weight of n-butyl acrylate and 10% of styrene in the presence of the polymer obtained in the above 1st stage. To 29% by weight, graft bonding monomer 1 to 5% by weight
In the presence of the second-stage polymer obtained by polymerizing a monomer mixture comprising: and (3) the polymers obtained in the first and second stages, 80 to 100% by weight of methyl methacrylate
And 0 to 20% by weight of another monomer copolymerizable therewith
Consisting of a third stage obtained by polymerizing a monomer mixture consisting of: a rubber-containing acrylic multi-stage polymer (B) having a ratio of the first-stage polymer, the second-stage polymer, and the third-stage polymer, 3 each
0 to 70% by weight, 10 to 40% by weight, 5 to 50% by weight, and the weight ratio of the first stage polymer to the second stage polymer is 1st stage polymer / 2nd stage polymer> 1 The acrylic resin composition according to claim 1, wherein 3. A molded article comprising the acrylic resin composition according to claim 1.