JPH05320457A - Acrylic resin composition - Google Patents

Abstract

PURPOSE:To obtain an acrylic resin compsn. improved in impact resistance and the temp. dependence of haze by compounding a rigid thermoplastic acrylic resin mainly comprising methyl methacrylate units with a specified amt. of a specific three-layered acrylic polymer. CONSTITUTION:A three-layered acrylic polymer is produced which comprises 10-30wt.% innermost rigid polymer layer prepd. from 80-98.99wt.% methyl methacrylate, 1-20wt.% 1-8C alkyl acrylate, and 0.01-5wt.% polyfunctional grafting agent, 35-50wt.% soft polymer layer, and 35-50wt.% outermost rigid polymer layer and has a mean particle diameter of 0.04-0.09mum and a grafting ratio (obtd. by fractionating with acetone) of 30wt.% or higher. 60-2 pts.wt. three-layered acrylic polymer is mixed with 40-98 pts.wt. rigid thermoplastic acrylic resin consisting of 80wt.% or higher methyl methacrylate units and 20wt.% or lower 1-8C alkyl acrylate units.

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, and more particularly to an acrylic resin composition excellent in transparency, impact resistance and haze temperature dependency. .. INDUSTRIAL APPLICABILITY The acrylic resin composition of the present invention can be suitably used for vehicle exterior parts used at relatively high temperatures, such as rear panels.

[0002]

2. Description of the Related Art Generally, a method of introducing a so-called elastomer component has been carried out as a means for improving the impact resistance of a hard thermoplastic acrylic resin. As one of such methods, it is common to introduce a diene elastomer, but since the diene elastomer has extremely poor weather resistance,
Not a suitable method for outdoor applications. In order to impart impact resistance to a hard acrylic resin without lowering weather resistance, various introductions of acrylic elastomers have been studied. In particular, as the acrylic elastomer, many examples of acrylic polymers having a multilayer structure have been proposed.

For example, a blend of a three-layer or four-layer or more multi-layer structure polymer and a thermoplastic polymer has improved impact resistance without impairing transparency (Japanese Patent Publication No. 55-27).
576) and a three-layer structure as a basis, and an intermediate layer having a concentration gradient that changes at a substantially constant rate between these layers (JP-B-58-1694 and JP-B-59-59).
No. 366455), having a three-layer structure as a basis and having one or more intermediate layers between the central soft layer and the outermost layer (Japanese Patent Publication No. 59-36646 and Japanese Patent Publication No. 63-8983), soft-hard The one having a soft-hard four-layer structure (Japanese Patent Publication No. 62-41241) has been proposed.

[0004]

As described above, the hard acrylic resin and the acrylic polymer having a multilayer structure are used for the purpose of improving the impact resistance while maintaining the preferable properties of the hard acrylic resin. Many proposals have been made regarding acrylic resin compositions. However,
These acrylic resin compositions were still not sufficiently satisfactory in regard to the temperature dependence of haze.
That is, by making the refractive indexes of the hard acrylic resin and the multi-layered acrylic polymer match at room temperature, the acrylic resin composition is transparent at room temperature. Since the temperature dependence of the refractive index is different, there has been a problem that the refractive index of both is shifted and the haze becomes large under a temperature condition higher or lower than room temperature.

Therefore, there is a strong need for a composition which can improve the drawbacks of the conventional acrylic resin composition concerning the temperature dependence of the haze and maintain the original excellent transparency of the acrylic resin in a wide temperature range. It has been requested.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to improve transparency, impact resistance and temperature dependency of haze of an acrylic resin composition, and as a result, a specific multilayer The inventors have found that the above-mentioned object can be achieved by using a structural acrylic polymer, and have completed the present invention.

That is, according to the present invention, a hard thermoplastic acrylic resin (A) comprising 80% by weight or more of a methyl methacrylate unit and 20% by weight or less of an alkyl acrylate unit having an alkyl group having 1 to 8 carbon atoms. An acrylic resin composition comprising 40 to 98 parts by weight and 2 to 60 parts by weight of a three-layer structure acrylic polymer (B), wherein the three-layer structure acrylic polymer (B) is (1) Methyl methacrylate 80-9
By polymerizing a monomer mixture consisting of 8.99% by weight, 1 to 20% by weight of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, and 0.01 to 5% by weight of a polyfunctional grafting agent. 10 to 30% by weight of the innermost hard layer polymer obtained, (2)
In the presence of the innermost hard layer polymer, 75 to 85% by weight of an alkyl acrylate having an alkyl group having 4 to 8 carbon atoms, 15 to 25% by weight of an aromatic vinyl compound, and a multifunctional crosslinking agent 0 to
5% by weight and polyfunctional grafting agent 0.05-5% by weight
35 to 50% by weight of a soft layer polymer obtained by polymerizing a monomer mixture consisting of (3) Methyl methacrylate 80 in the presence of the polymer consisting of the innermost hard layer and the soft layer.
To 99 wt% and 1 to 20 wt% of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, the outermost hard layer polymer obtained by polymerizing 35 to 50 wt%
(4), and the average particle diameter of the three-layer structure polymer is 0.04 to 0.09 μm, and (5)
Further, the acrylic resin composition is characterized in that a graft ratio when the three-layer structure polymer is fractionated with acetone is 30% by weight or more.

The present invention will be described below. The hard thermoplastic acrylic resin (A) of the present invention is obtained by polymerizing 80% by weight or more of a methyl methacrylate unit and 20% by weight or less of an alkyl acrylate unit having an alkyl group having 1 to 8 carbon atoms. is there. Here, an alkyl acrylate having 1 to 8 carbon atoms
Examples include methyl acrylate and ethyl acrylate
, N-butyl acrylate, i-butyl acrylate
And 2-ethylhexyl acrylate, and the like, and methyl acrylate and ethyl acrylate are particularly preferably used.

The proportion of alkyl acrylate units in the hard thermoplastic acrylic resin (A) is preferably 1 to 20% by weight. When the unit is less than 1% by weight, the effect of lowering the melt viscosity of the hard thermoplastic acrylic resin (A) is insufficient,
The fluidity during molding is reduced. In addition, the heat decomposability of the resin is increased, and silver streak easily occurs on the surface of the molded product, which is not preferable. On the other hand, if the unit exceeds 20% by weight,
Since the heat distortion temperature of the resin is lowered and the molded product is likely to be heat deformed, only a practically poor product can be obtained.

The hard thermoplastic acrylic resin (A) of the present invention preferably has a reduced viscosity (ηsp / C) at 25 ° C. of 30 to 90 ml / g in chloroform. When the reduced viscosity is less than 30 ml / g, the mechanical strength of the resin is remarkably reduced, and the molded product is easily damaged during molding and during use. On the other hand, the reduced viscosity is 90 ml / g
If it exceeds, the melt viscosity of the resin increases and the moldability decreases, which is not preferable. The reduced viscosity is 40
~ 80 ml / g is particularly preferred.

The method for producing the hard thermoplastic acrylic resin (A) in the present invention is not particularly limited, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. .. Here, as the polymerization initiator, usual peroxide type and azo type initiators can be used, and also redox type can be used. The polymerization temperature is 30 for suspension or emulsion polymerization.
˜100 ° C., bulk or solution polymerization can be carried out at 80˜160 ° C. Further, in order to control the reduced viscosity of the produced resin, alkylmercaptan or the like can be used as a chain transfer agent to carry out the polymerization.

The innermost hard layer polymer constituting the three-layer structure acrylic polymer (B) is methyl methacrylate 80-9.
Obtained by polymerizing a monomer mixture comprising 8.99% by weight, 1 to 20% by weight of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, and 0.01 to 5% by weight of a polyfunctional grafting agent. Be done. Here, as the alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, those described in the section of the hard thermoplastic acrylic resin (A) are used. The ratio of the alkyl acrylate unit in the innermost hard layer polymer is 1 to 20.
When the content of the unit is less than 1% by weight, the thermal decomposability of the polymer becomes large, while when the content of the unit exceeds 20% by weight, the glass transition temperature of the innermost hard layer polymer becomes low.
All of these are not preferable because the impact resistance imparting effect of the three-layer structure acrylic polymer decreases.

Examples of the polyfunctional grafting agent include polyfunctional monomers having different polymerizable functional groups such as allyl esters of acrylic acid, methacrylic acid, maleic acid and fumaric acid. -G is preferably used. The polyfunctional grafting agent is used to chemically bond the innermost hard layer polymer and the softer layer polymer, and the proportion used during the innermost hard layer polymerization is 0.01 to 5% by weight.
Is. When the proportion of the units is out of this range, the impact resistance imparting effect of the three-layer structure acrylic polymer is deteriorated, which is not preferable.

The soft layer polymer constituting the three-layer structure acrylic polymer (B) is an alkyl acrylate 75 having an alkyl group with 4 to 8 carbon atoms in the presence of the innermost hard layer polymer.
~ 85 wt%, aromatic vinyl compound 15-25 wt%,
It is obtained by polymerizing a monomer mixture consisting of 0 to 5% by weight of a polyfunctional crosslinking agent and 0.05 to 5% by weight of a polyfunctional grafting agent. Here, as the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, those described in the section of the hard thermoplastic acrylic resin (A) are used, but n-butyl methacrylate and 2- Ethylhexyl methacrylate is preferably used. It Examples of aromatic vinyl compounds include styrene and substituted styrene derivatives, with styrene being preferred. Further, the ratio of the alkyl acrylate and the aromatic vinyl compound is such that the glass transition temperature of the produced polymer decreases as the former amount increases, that is, the resin can be softened, but from the viewpoint of transparency of the resin composition. It is more advantageous to bring the refractive index of the soft layer polymer at room temperature closer to that of the innermost hard layer polymer, the outermost hard layer polymer, and the hard thermoplastic acrylic resin (A). The ratio of the two is selected in consideration of these, but generally 75 to 85% by weight of alkyl acrylate and 15 to 25 of aromatic vinyl compound.
A range of weight percent is used.

As the polyfunctional grafting agent, those mentioned in the item of the innermost layer hard polymer can be used.
The polyfunctional grafting agent used here is used to chemically bond the soft layer polymer and the outermost hard layer polymer,
The ratio used during the innermost hard layer polymerization is 0.01 to 5% by weight. When the proportion of the units is out of this range, the impact resistance imparting effect of the three-layer structure acrylic polymer is deteriorated, which is not preferable.

As the polyfunctional crosslinking agent, generally known crosslinking agents such as divinyl compounds, diallyl compounds, diacryl compounds and dimethacryl compounds can be used, but polyethylene glycol diacrylate (molecular weight 2
00-600) is preferably used. The polyfunctional cross-linking agent used here generates a cross-linking structure during polymerization of the soft layer,
It is used to exert the effect as an elastic body. However, if the above-mentioned polyfunctional grafting agent is used during the polymerization of the soft layer, a crosslinked structure of the soft layer is generated to some extent, and thus the polyfunctional crosslinking agent is not an essential component. That is, the proportion of the polyfunctional crosslinking agent used in the soft layer polymerization is 0 to 5% by weight. If the proportion of the units exceeds 5% by weight, the impact resistance imparting effect of the three-layered structure acrylic polymer decreases, which is not preferable.

The outermost hard layer polymer constituting the three-layer structure acrylic polymer (B) is methyl methacrylate 80 to 9 in the presence of the above innermost hard layer polymer and soft layer polymer.
It is obtained by polymerizing a monomer mixture consisting of 9% by weight and 1 to 20% by weight of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms. Here, as the alkyl acrylate, those described in the item of the hard thermoplastic acrylic resin (A) are used, but methyl acrylate and ethyl acrylate are preferably used. The ratio of alkyl acrylate units in the outermost hard layer is 1 to 20.
Weight percent is preferred. When the amount of the unit is less than 1% by weight, the thermal decomposability of the polymer becomes large, while the amount of the unit is 20% by weight.
When it exceeds the above range, the adhesiveness of the three-layer structure acrylic polymer particles increases, making it difficult to handle in post-treatment and the like, and reducing the compatibility with the thermoplastic acrylic resin (A), resulting in impact resistance and weather resistance. You can only get something inferior to

In order to improve the compatibility with the thermoplastic acrylic resin (A) at the time of polymerizing the outermost hard layer, alkylmercaptan or the like may be used as a chain transfer agent to adjust the molecular weight, and this may be carried out. In order to obtain an acrylic resin composition having a good balance of haze temperature dependence and impact resistance, which is the object of the present invention, the ratio of each layer polymer in the three-layer structure acrylic polymer (B) is controlled. Is extremely important. That is, the multi-layered acrylic polymer (B)
The ratio of each layer polymer in the innermost hard layer is 10 to 30.
% By weight, 35-50% by weight for the soft layer and 35-50% by weight for the outermost hard layer. Here, if the ratio of the innermost hard layer polymer is less than 10% by weight, the temperature dependence of the haze becomes large and it becomes difficult to completely carry out the seed polymerization, while it exceeds 30% by weight. And the effect of imparting impact resistance decreases, which is not preferable. When the ratio of the soft layer polymer is less than 35% by weight, the effect of imparting impact resistance is poor, while when it exceeds 50% by weight, the temperature dependence of the haze becomes large, which is not preferable. Further, when the ratio of the outermost hard layer polymer is less than 35% by weight, the haze temperature dependency and impact resistance imparting effect are poor, while when it exceeds 50% by weight, impact resistance imparting. Both of them are not preferable because they are less effective.

In order to obtain an acrylic resin composition having a good balance of haze temperature dependence and impact resistance, which is the object of the present invention, the ratio of each layer polymer in the three-layer structure acrylic polymer (B). It is important to control the average particle diameter as well as to control. The average particle diameter of the multi-layered acrylic polymer (B) of the present invention is required to be 0.04 to 0.09 μm, preferably 0.05 to 0.08 μm. When the average particle diameter is less than 0.04 μm, the effect of imparting impact resistance is poor, while when it exceeds 0.09 μm%, the temperature dependence of the haze is large, which is not preferable.

When the acrylic polymer (B) having a three-layer structure of the present invention is produced by an emulsion polymerization method, the average particle size is determined by the type of emulsifier, the ratio of the emulsifier to the aqueous phase and the monomer mixture phase, and the innermost hardness. It can be controlled by the addition rate of the monomer mixture phase to the aqueous phase at the time of layer formation and the polymerization temperature, within the range of techniques widely known to those skilled in the art. Further, the average particle size can be measured by a known method such as a transmission electron microscope observation of the latex at the end of the emulsion polymerization, an absorbance method, or a light scattering method. The particle size of the three-layer acrylic polymer (B) can also be measured by making an acrylic resin composition into an ultrathin section, dyeing the soft layer with ruthenium tetroxide, and then observing with a transmission electron microscope. However, in this case, it should be noted that the contour up to the soft layer is observed, and the contour of the outermost hard layer is indistinguishable from the hard thermoplastic acrylic resin (A).

In order to obtain an acrylic resin composition having a good balance between the temperature dependence of haze and impact resistance, which is the object of the present invention, a three-layer structure acrylic polymer is fractionated with acetone. It is also important to control the graft rate. The graft ratio of the three-layer structure acrylic polymer (B) of the present invention is 30% by weight or more. When the graft ratio is less than 30% by weight, the temperature dependence of haze and the effect of imparting impact resistance are poor, which is not preferable.

The three-layer structure acrylic polymer (B) in the present invention is produced by sequential multistage polymerization, and it is preferable to use an emulsion polymerization method as the polymerization method. Further, in the presence of the innermost layer hard polymer, when forming the soft layer polymer, and further the outermost hard layer polymer, it is necessary that no new particles are generated, and for this purpose the seed is used. A polymerization method is preferably used. That is, when all three layers are polymerized by an emulsion polymerization method, no new emulsifier is added or new particles are not generated when the soft layer and the outermost hard layer are polymerized. It is important to stay within range. Further, the presence or absence of new particle formation can be confirmed by observing the latex with an electron microscope.
Suitable polymerization temperature for forming the polymer of each layer is selected in the range of 30 to 120 ° C, preferably 50 to 100 ° C for each layer.

Regarding the emulsifier used in the emulsion polymerization,
There is no particular limitation, and any one can be selected from those conventionally used. Examples thereof include long-chain alkylcarboxylic acid salts, sulfosuccinic acid alkyl ester salts, and alkylbenzene sulfonic acid salts. Further, the polymerization initiator used at this time is not particularly limited, and a commonly used inorganic initiator such as water-soluble persulfate or perborate alone, or sulfite, thiosulfate, etc. Can also be used in combination as a redox initiator system. In addition, redox initiator systems such as oil-soluble organic peroxide / ferrous salts, organic peroxide / sodium sulfoxylate can also be used.

The three-layer structure acrylic polymer obtained by such an emulsion polymerization method is a solid particulate material obtained by subjecting a polymer latex state to a treatment such as salting out, washing and drying by a known method. Obtained as. The acrylic resin composition of the present invention comprises 40 to 98 parts by weight of a hard thermoplastic acrylic resin (A) and 2 to 60 parts by weight of a three-layer structure acrylic polymer (B) (total 100 parts by weight). is there. When the proportion of the three-layer structure acrylic polymer (B) in the composition is less than 2 parts by weight, impact resistance is insufficient, and when it exceeds 60 parts by weight, color tone and temperature dependence of haze, Heat resistance and weather resistance are inferior, which is not preferable.

The production of the acrylic resin composition of the present invention is
It can be carried out by melt-kneading the three-layer structure acrylic polymer (B) with the hard thermoplastic acrylic resin (A) using an extruder or the like. When kneading to produce an acrylic resin composition, an antioxidant, an ultraviolet absorber, an antistatic agent, a plasticizer, a lubricant, a dye, a pigment, etc. are added as necessary and do not impair the original properties of the resin composition. It can also be added in a range.

By subjecting the acrylic resin composition thus obtained to injection molding or extrusion molding,
It is possible to obtain a molded product or sheet having excellent impact resistance and having a reduced haze temperature dependency.

[0027]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. The measurements in Examples and Comparative Examples were performed using the following methods or measuring instruments. [Izod impact strength]; ASTM D256 haze; using an integrating sphere type haze meter, thickness 1 /
The haze of the 8-inch test piece at 23 ° C and 70 ° C was measured.

[Average particle size]: A latex of a three-layer structure acrylic polymer was sampled to obtain a solid content of 50 ppm.
Dilute with water to a wavelength of 55 with a spectrophotometer.
Absorbance at 0 nm was measured. From this value, the average particle size was determined using a calibration curve prepared by similarly measuring the absorbance of the sample whose latex particle size was measured from a transmission electron micrograph.

[Graft ratio]; 3 in the form of dry powder
Precisely weigh about 0.3 g of the layered acrylic polymer (W1),
30 ml of acetone is added and the mixture is left standing overnight at room temperature and then shaken for 2 hours. Centrifuge at 2 ° C. and 26000 rpm for 1 hour. After removing the supernatant liquid by decantation, 30 ml of acetone is newly added and shaken at room temperature for 1 hour. After shaking, the mixture is centrifuged at 2 ° C. and 26000 rpm for 1 hour, the supernatant is decanted off, and air dried overnight.
After vacuum drying at 100 ° C. for 4 hours and cooling to room temperature in a desiccator, the weight of the residue is weighed (W2). The acetone-insoluble portion {(X):% by weight} is calculated by the following formula.

Acetone insoluble part (X) = (W2 ÷ W1) × 100 The weight% of the innermost hard layer polymer and the soft layer polymer in the three-layer structure acrylic polymer (B) are respectively Y and Z.
Then, the graft ratio (% by weight) is calculated by the following formula. Graft ratio = {(X−Y−Z) ÷ (Y + Z)} × 100 Further, the abbreviations used in Examples and Comparative Examples represent the following compounds.

MMA; methyl methacrylate BA; n-butyl acrylate St; styrene MA; methyl acrylate ALMA; allyl methacrylate PEGDA; polyethylene glycol diacrylate (molecular weight 200) DPBHP; diisopropylbenzene hydroper -Oxide n-OM; n-octyl mercaptan

[0032]

Example 1 6360 ml of ion-exchanged water and 35.3 g of sodium dioctylsulfosuccinate were placed in a reactor with a reflux condenser having an internal volume of 10 liters, and the mixture was heated to 80 ° C. under a nitrogen atmosphere while stirring at 250 rpm. It was heated so that it was virtually free of oxygen. Five minutes after adding 1.4 g of sodium formaldehyde sulfoxylate, MMA721.7 g, BA11.8 g, ALMA
30% by weight of the monomer mixture consisting of 0.73 g and 0.73 g of DPBHP was added all at once, and immediately after that, the remaining 70% by weight was continuously added over 20 minutes, and after that addition was maintained for 60 minutes. Then, the polymerization of the innermost layer was completed.

Then, 1.1 g of sodium formaldehyde sulfoxylate was added, and 5 minutes later, BA84 was added.
5.5g, St198.3g, ALMA2.1g, PE
A monomer mixture consisting of 8.4 g of GDA and 1.0 g of DPBHP was continuously added over 120 minutes, and after the addition was completed, the mixture was kept for 180 minutes to complete the polymerization of the soft layer.

Next, 981 g of MMA, 67.6 g of BA,
A monomer mixture consisting of 1.0 g of DPBHP and 3.1 g of n-OM was continuously added over 40 minutes, and the mixture was kept for 60 minutes after the addition was completed. Then, raise the temperature to 95 ° C. and
Hold for 0 minutes to complete the polymerization of the outermost layer. A small amount of the polymer latex thus obtained was sampled, and the average particle size was determined by the absorbance method to find that it was 0.075 μm.

The remaining latex was put into a 3% by weight aqueous solution of sodium sulfate to salt out and coagulate, and then dehydration and washing were repeated and then dried to obtain a three-layer structure acrylic polymer (B-1). Was obtained as a powder. The graft ratio of the three-layer structure acrylic polymer was 35% by weight. 20 parts by weight of this three-layer structure acrylic polymer (B-1) and MMA / MA = 97.5 / 2.5 parts by weight in chloroform have a reduced viscosity (ηsp / C) of 54 at 25 ° C.
Hard thermoplastic acrylic resin (A-1) 8 with ml / g
After mixing with 0 part by weight in a Henschel mixer for 20 minutes, a 30 mm vented twin-screw extruder (manufactured by Nakatani Machine, A
Pellets at 240 ° C. The obtained pellets are in-line screw-injection molding machine (manufactured by Toshiba Machine,
(IS-75S type), predetermined test pieces were prepared under the conditions of a molding temperature of 250 ° C., an injection pressure of 900 kgf / cm ² , and a mold temperature of 50 ° C., and physical properties were measured.

The resin composition thus obtained was excellent in transparency, temperature dependency of haze, and good in impact resistance. The results are shown in Table 1.

[0037]

Example 2 In Example 1, the ratio of the innermost layer, the softest layer and the outermost layer was changed as shown in Table 1 to obtain a three-layer structure acrylic polymer (B-2). It was carried out in exactly the same manner as 1. The results are shown in Table 1.

[0038]

Example 3 157 liters of ion-exchanged water and 876 g of sodium dioctylsulfosuccinate were placed in a closed pressure-resistant reactor having an internal volume of 250 liters, and the temperature was raised to 80 ° C. under a nitrogen atmosphere while stirring at 250 rpm. , So that the effect of oxygen is virtually eliminated. 5 minutes after adding 34.8 g of sodium formaldehyde sulfoxylate, MMA10820g, BA151g, ALMA
30% of the monomer mixture consisting of 11.0 g and 11.0 g of DPBHP was added all at once, and immediately after that, the remaining 70% was continuously added over 20 minutes, and after the addition was complete, hold for 60 minutes. The polymerization of the innermost layer was completed.

Next, 27.9 g of sodium formaldehyde sulfoxylate was added, and after 5 minutes, BA20 was added.
730g, St4863g, ALMA256g, PEG
A monomer mixture consisting of 66.5 g of DA and 25.6 g of DPBHP was continuously added over 120 minutes, and after the addition was completed, the mixture was kept for 180 minutes to complete the polymerization of the soft layer.

Next, MMA30940g and BA1975
g, DPBHP 32.9 g and n-OM 98.7 g monomer mixture continuously added over 40 minutes,
After the addition was completed, it was held for another 60 minutes. Then, the temperature was raised to 95 ° C. and kept for 60 minutes to complete the polymerization of the outermost layer.
A small amount of the polymer latex thus obtained was sampled, and the average particle size was determined by absorptiometry.
was μm.

The polymer latex thus obtained is salted out and coagulated, then dehydrated and washed repeatedly, and dried to obtain a three-layer structure acrylic polymer (B-3) as a powder. It was Using this, the following was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0042]

[Comparative Example 1] 5700 ml of ion-exchanged water and 21.0 g of sodium dioctylsulfosuccinate were placed in a reactor with a reflux condenser having an internal volume of 10 liters, and the mixture was heated to 80 ° C. under a nitrogen atmosphere while stirring at 250 rpm. It was heated so that it was virtually free of oxygen. Five minutes after adding 1.2 g of sodium formaldehyde sulfoxylate, 220 g of MMA, 7 g of BA, 0.6 g of ALMA,
Then, a monomer mixture consisting of 0.23 g of DPBHP and DPBHP was added, and after the addition was completed, the mixture was kept for another 20 minutes to complete the polymerization of the innermost layer.

Next, 1.1 g of sodium formaldehyde sulfoxylate was added, and 5 minutes later, BA130 was added.
0g, St300g, ALMA17g, PEGDA12
and a monomer mixture consisting of 1.6 g of DPBHP were continuously added over 90 minutes, and a further 12 minutes after the addition was completed.
Hold for 0 minutes to complete the polymerization of the soft layer. Then M
A monomer mixture consisting of 640 g of MA, 40 g of BA, 0.7 g of DPBHP and 2.0 g of n-OM was continuously added over 20 minutes, and the mixture was kept for 60 minutes after the addition was completed. Then, the temperature was raised to 95 ° C. and kept for 60 minutes to complete the polymerization of the outermost layer.

A small amount of the polymer latex thus obtained was sampled, and the average particle size was determined by an absorptiometry to find that it was 0.089 μm. The polymer latex thus obtained was salted out and coagulated, then dehydrated and washed repeatedly, and then dried to obtain a three-layer structure acrylic polymer (B-4) as a powder. The graft ratio of this three-layer structure acrylic polymer was 26% by weight.

Using this, the following steps were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0046]

[Comparative Examples 2 to 7] In Comparative Example 1, the innermost layer, the soft layer,
The ratio of the outermost layer and the average particle diameter were changed as shown in Table 1 to obtain a three-layer structure acrylic polymer (B-5 to 9), and the compounding amount was changed in the same manner as in Comparative Example 1. It was carried out. The results are shown in Table 1. As described above, when the content of the acrylic resin composition deviates from the scope of the present invention, it is not possible to obtain an acrylic resin composition having a good balance of transparency, temperature dependence of haze and impact resistance.

[0047]

[Table 1]

[0048]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide an acrylic resin composition which has excellent transparency and molding processability inherent in an acrylic resin, and is excellent in impact resistance and haze temperature dependency. it can.

Claims (1)

[Claims] 1. An alkyl acrylate having a methyl methacrylate unit of 80% by weight or more and an alkyl group having 1 to 8 carbon atoms.
An acrylic resin composition comprising 40 to 98 parts by weight of a hard thermoplastic acrylic resin (A) composed of 20% by weight or less of a unit and 2 to 60 parts by weight of a three-layer structure acrylic polymer (B), The three-layer structure acrylic polymer (B) is (1) methyl methacrylate 80 to 98.99% by weight,
Alkyl acrylate 1 whose alkyl group has 1 to 8 carbon atoms
˜20% by weight, and multifunctional grafting agent 0.01 to 5
10 to 30% by weight of the innermost hard layer polymer obtained by polymerizing a monomer mixture consisting of 5% by weight, (2) In the presence of the innermost hard layer polymer, the number of carbon atoms of the alkyl group is 4 to 8 Alkyl acrylate 75-85% by weight, aromatic vinyl compound 15-25% by weight, polyfunctional crosslinking agent 0-5% by weight and polyfunctional grafting agent 0.05-
35 to 50% by weight of a soft layer polymer obtained by polymerizing a monomer mixture of 5% by weight, (3) Methyl methacrylate in the presence of the above-mentioned polymer of the innermost hard layer and the soft layer. Alkyl acrylate 1 having 80 to 99% by weight and 1 to 8 carbon atoms in the alkyl group
The outermost hard layer polymer obtained by polymerizing a monomer mixture of 20 to 20% by weight has a three-layer structure of 35 to 50% by weight, and (4) and the average particle of the three-layer structure polymer. Diameter is 0.04 ~
0.09 μm, (5) Furthermore, the graft ratio when the three-layer structure polymer is fractionated with acetone is 30% by weight or more, and the acrylic resin composition.