JPH0657082A - Acrylic resin composition - Google Patents

Abstract

PURPOSE:To provide the acrylic resin composition having low adhesivity to metal and excellent moldability, transparency, weather resistance, impact resistance and tensile elongation by compounding a specific amount of a specific compound to an acrylic copolymer and an acrylic polymer having a multilayer structure. CONSTITUTION:The resin composition is produced by compounding (A) 45-80 pts.wt. of an acrylic polymer having a multilayer structure with (B) 20-55 pts.wt. of an acrylic copolymer having a reduced viscosity of 30-120g/ml measured in chloroform at 25 deg.C and composed of 80-99wt.% of methyl methacrylate unit and 1-20wt.% of an alkyl acrylate unit having a 1-4C alkyl group and compounding 100 pts.wt. of the obtained composition with (C) 0.01-5 pts.wt. of a glycerol ester of a 14-20C saturated fatty acid (e.g. glycerol monomyristate). The compound A is preferably produced by using methyl methacrylate, an alkyl acrylate having a 1-8C alkyl group and a graft-bonding monomer as essential components and copolymerizing the monomers by seed-polymerization.

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 having excellent transparency, releasability, weather resistance, tensile elongation and impact resistance.

[0002]

2. Description of the Related Art Since polymethylmethacrylate is excellent in transparency, weather resistance and surface hardness, it is widely used in automobile exterior parts, exterior parts, optical lenses, optical disks and the like both indoors and outdoors. However, since polymethylmethacrylate has relatively strong adhesion to metal and is brittle, in injection molding, defects such as cracks and cracks in molded products are likely to occur due to defective release from the mold,
Further, in extrusion molding, there is a problem that quality defects such as die lines are likely to occur.

As a technique for improving the releasability of polymethylmethacrylate, for example, at least one kind of ester of polyhydric alcohol and fatty acid, monovalent alkyl alcohol, fatty acid, fatty acid amide and fatty acid metal salt is added. Method (JP-A-61-73754), method of adding glycerin higher fatty acid ester and saturated aliphatic alcohol (JP-A-1-294763), at least glyceride stearate, glyceride behenate, and fatty acid alkyl ester Method of adding one kind (JP-A-2-
No. 115255) is known.

On the other hand, as a technique for improving impact resistance of polymethylmethacrylate, for example, a blend of a multi-stage polymer having three layers or more and a thermoplastic polymer to improve impact resistance without impairing transparency ( Japanese Patent Publication Sho 55-27
No. 576), a three-layer structure is basically used, and an intermediate layer having a concentration gradient that changes at a substantially constant rate is provided between these layers (Japanese Patent Publication No. 58-1694), basically a hard layer-soft layer. Layer-hard layer three-layer structure in which the molecular weight of the outermost hard layer gradually decreases from the inner side to the outer side (Japanese Patent Publication No. 60-17406), a specific soft layer ratio and an average particle diameter. Further, there is known one having a three-layer structure of a hard layer-soft layer-hard layer having a graft ratio and a tensile elastic modulus of an acetone-insoluble portion (JP-A-3-199213).

[0005]

However, in the case of injection molding or profile extrusion molding of a molded product having a complicated shape, or molding of a thin film, for example, when the above additive is added to polymethylmethacrylate Although it is possible to improve the releasability according to the amount of additive, it is impossible to obtain a molded product having a good surface because the additive is deposited on the inner surface of the mold and the lip portion of the die when the amount of addition is large. There was a problem. On the other hand, when an impact-resistant acrylic resin is used, mechanical strength is improved and defects such as cracks are reduced, but the releasability of the resin itself is not improved.For example, the molded product is removed from the mold during injection molding. However, there were still problems such as whitening of the molded product due to the protruding pin when it was removed, and none of them could be said to have completely solved the problem.

In particular, tensile elongation and flexibility are often required for thin film applications, and polymethylmethacrylate is blended with a large amount of a multi-layered acrylic polymer as an elastomer component, resulting in better adhesion to metal. There was a problem that the product line value became stronger and the die line was likely to appear at the time of film forming, which markedly impaired the commercial value. Further, as described in JP-B-58-1694 or JP-B-60-17406, attempts have been made to prevent stress whitening by imparting a special structure to a multi-layered acrylic polymer. This alone did not improve the adhesion to metal, and quality problems such as die line generation in extrusion molding were still unsolved.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have found that polymethyl methacrylate easily adheres to a metal and is brittle, so that problems such as cracks, cracks, die lines, etc. occur during molding. We have conducted intensive research with the purpose of fundamentally solving problems. As a result, it was found that a significant effect can be obtained by adding an appropriate amount of a specific compound to a resin composition composed of a multi-layered acrylic polymer and an acrylic copolymer, and the present invention has been completed. It was

That is, according to the present invention, 45 to 80 parts by weight of a multi-layered acrylic polymer (A), 80 to 99% by weight of a methyl methacrylate unit, and 1 to 10 carbon atoms of an alkyl group.
4 of 1 to 20% by weight of alkyl acrylate unit and has a reduced viscosity of 30 at 25 ° C. in chloroform.
~ 120 g / ml of acrylic copolymer (B) 20
~ 55 parts by weight (where (A) and (B) total 10
0 parts by weight), and at least one kind of glycerin ester of saturated fatty acid having 14 to 20 carbon atoms 0.0
The acrylic resin composition comprises 1 to 5 parts by weight.

The multi-layered acrylic polymer (A) in the present invention contains methyl methacrylate, an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, and a graft-bonding monomer as essential components, and if necessary, other Any polymer having a multi-layer structure of three layers or four or more layers composed of the vinyl monomer or polyfunctional cross-linkable monomer may be used. For example, one having a three-layer structure of hard layer-soft layer-hard layer, one having a five-layer structure of hard layer-soft layer-hard layer-soft layer-hard layer, soft layer-hard layer-soft layer-hard Having a four-layer structure of layers, basically a three-layer structure of hard layer-soft layer-hard layer, having an intermediate layer in which the composition changes substantially at a constant rate (hard layer-intermediate) Layer-soft layer-hard layer, hard layer-soft layer-intermediate layer-hard layer, hard layer-intermediate layer-soft layer-
Intermediate layer-hard layer, etc.), which basically has a three-layer structure, in which the molecular weight of the outermost hard layer is gradually reduced from the inner side to the outer side.

Furthermore, the hard layer is obtained by polymerizing 80 to 99% by weight of methyl methacrylate and 1 to 20% by weight of methyl methacrylate and other copolymerizable vinyl monomers. The layer has 70 to 99% by weight of an alkyl acrylate having 2 to 8 carbon atoms in the alkyl group and 0 to 25% by weight of another vinyl monomer copolymerizable with the alkyl acrylate, and 0.1 to 8% by weight. It is preferable that it is obtained by polymerizing the graft-bonding monomer (1) and the polyfunctional crosslinking monomer (0 to 5% by weight). Here, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene and the like are used as the other vinyl monomer copolymerizable with the methyl methacrylate of the hard layer, and copolymerized with the alkyl acrylate of the soft layer. Examples of possible monomers include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, styrene and the like.

As the graft-bonding monomer, commonly used crosslinking agents such as divinyl compounds, diallyl compounds, diacryl compounds and dimethacryl compounds can be used. Examples of the graft-bonding monomer include polyfunctional monomers having different functional groups, such as allyl esters of acrylic acid, methacrylic acid, maleic acid and fumaric acid.

The multi-layered acrylic polymer (A) is produced by emulsion polymerization, but it does not generate new particles when the hard layer except the innermost hard layer, the soft layer and the intermediate layer are polymerized. It is important to choose the conditions and the so-called seed polymerization method is used for this purpose. When the polymerization of the next layer is carried out, it is necessary not to add a new emulsifier, or if it is necessary to add it, it is necessary to keep it within a range where new particles are not formed. The presence or absence of new particles can be easily detected by an electron microscope.

The emulsifier used for emulsion polymerization is not particularly limited, 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. Also, the polymerization initiator is not particularly limited, and a commonly used inorganic initiator such as water-soluble persulfate or perborate alone or in combination with sulfite, thiosulfate or the like is used. It can be used as a redox initiator system. Furthermore ,. Redox initiator systems such as soluble organic peroxide / sodium sulfoxylate can also be used.

The particle size of the multi-layered acrylic polymer (A) is preferably in the range of 0.05 to 0.5 μm, and the particle size of 0.05 to 0.
The range of 3 μm is more preferable. The thus obtained multi-layered acrylic polymer (A) can be recovered as a particulate solid by performing treatments such as salting out, washing and drying from the state of the polymerized latex by a known method.

Acrylic copolymer (B) in the present invention
Is composed of 80 to 99% by weight of a methyl methacrylate unit and 1 to 20% by weight of an alkyl acrylate unit in which an alkyl group has 1 to 4 carbon atoms. If the proportion of alkyl acrylate units in the copolymer exceeds 20% by weight, the solvent resistance of the composition decreases, and if it is less than 1% by weight, thermal decomposition tends to occur, which is not preferable. As the alkyl acrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate and the like are usually used industrially. The reduced viscosity of the copolymer measured at 25 ° C. in chloroform is 30 to 120 g / ml, and the reduced viscosity is 35 to 100.
g / ml is preferred. If the reduced viscosity is less than 30 g / ml, the composition is inferior in impact resistance and solvent resistance.
If it exceeds 1 / g, the molding processability is deteriorated, so that both are not preferable.

There is no particular limitation on the polymerization method of the acrylic copolymer (B), and the acrylic copolymer (B) can be produced by a radical polymerization method which is generally used industrially, that is, suspension polymerization, bulk polymerization or solution polymerization. The ratio of the multi-layered acrylic polymer (A) and the acrylic copolymer (B) in the acrylic resin composition of the present invention is 45 to 80 parts by weight for (A) and 20 to 55 parts by weight for (B). (Here (A) and (B)
Is 100 parts by weight). When (A) is less than 45 parts by weight in 100 parts by weight of the composition, the impact resistance and tensile elongation are poor, and when it exceeds 80 parts by weight, the fluidity of the composition is low and the processability is poor. Not preferable.

The fatty acid used in the present invention has 14 to 2 carbon atoms.
As the saturated fatty acid glycerin ester which is 0, glycerin monofatty acid ester such as glycerin monomyristate, glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, glycerin dimyristate, glycerin dipalmitate, Examples thereof include glycerin difatty acid esters such as glycerin distearate and glycerin dibehenate, or a mixture of two or more kinds thereof.

The amount of the saturated fatty acid glycerin ester added is 0.01 part by weight based on 100 parts by weight of the acrylic resin composition comprising the multi-layered acrylic polymer (A) and the acrylic copolymer (B) in the present invention. If it is less than 5 parts by weight, the effect of improving the releasability of the composition is insufficient. On the other hand, if it is added in an amount of more than 5 parts by weight, no remarkable effect of improving the releasability is seen, and it is not preferable because it is not costly. . Further, if added in a too large amount, the heat resistance of the composition is lowered, and a part of the composition is deposited on the surface of the mold or the lip portion of the extrusion die during processing, which causes a surface defect of the molded product, which is not preferable.

The method for producing the composition of the present invention is not particularly limited, and known methods can be adopted. For example, a method of mixing the multi-layered acrylic polymer (A), the acrylic copolymer (B), and the saturated fatty acid glycerin ester at a desired ratio with a tumbler or a mixer, and pelletizing the mixture using an extruder can be mentioned. You can In addition, an ultraviolet absorber, an antioxidant, a light diffusing agent, a dye, a pigment or the like can be added, if necessary, in the range of blending, so long as the effects of the present invention are not impaired.

Furthermore, a film or sheet can be manufactured using the obtained pellets.

[0021]

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 carried out using the method described below or a measuring instrument. (1) Average particle size A small amount of a latex sample, the average particle size of which was previously measured using a transmission electron micrograph, was taken, diluted with water to a solid content of 50 ppm, and then used with a spectrophotometer. Then, the absorbance at a wavelength of 550 nm is measured, and a calibration curve for the average particle diameter and the absorbance is created. Similarly, the absorbance of the latex sample to be measured is measured, and the average particle size is obtained from the calibration curve. (2) Weight average molecular weight 50 mg of the polymer is dissolved in 30 ml of tetrahydrofuran to prepare a sample solution, and the weight average molecular weight is obtained from the calibration curve by standard PMMA by gel permeation chromatography (GPC) method. (3) Haze The haze of a test piece having a thickness of 0.4 mm at 23 ° C. was measured using an integrating sphere type haze meter. (4) Izod impact strength AST for test pieces with a thickness of 3 mm prepared by injection molding
It is measured based on the method of MD 256. (5) Tensile test Using a Shimadzu AG-10kND, a tensile speed of 20
0.4 mm thickness at 0 mm / min and chuck distance of 50 mm
The elongation of a strip test piece of m is measured. (6) Releasability A four-stage plate mold as shown in FIG. 1 was attached to the injection molding machine, and molding was performed under the conditions of molding temperature of 260 ° C., mold temperature of 50 ° C., and injection pressure of 1000 kg / cm ^2. When the molded product is cracked, bent, or whitened when it is performed, it is regarded as a defective product, and the ratio of defective products among all molded products is defined as the defective occurrence rate. The sample was molded for 200 shots to keep the injection molding conditions constant,
100 shot molding was performed and evaluated. That is, the total number of samples is 100.

Prior to molding, the pellets were dried, and the pellets were molded at a water content of 0.06% by weight or less. (7) Evaluation of mold surface haze After molding 100 shots for mold release evaluation, the surface of the mold is observed and the degree of haze is ranked.

○ No fogging △ Slight fogging × Fogging, or significant fogging (8) Weather resistance test Sunshine weather meter (hereinafter S) manufactured by Suga Test Instruments Co., Ltd.
Abbreviated as WOM) using a sunshine super long life carbon, the temperature is constant at 63 ° C., and after irradiation for 2000 hours under the condition that the cycle without rainfall (2 hours) and with rainfall (18 minutes) is repeated. Visually observe the sample.

The abbreviations used in Examples and Comparative Examples indicate the following compounds. MMA; methyl methacrylate BA; n-butyl acrylate MA; methyl acrylate St; styrene ALMA; allyl methacrylate PEGDA; polyethylene glycol diacrylate (molecular weight 200) DPBHP; diisopropylbenzene hydroperoxide n -OM; n-octyl mercaptan DBPMS; 1,1-di-t-butylperoxy-3,
3,5-Trimethylcyclohexane EB; Ethylbenzene LPO; Lauroyl Peroxide Further, unless otherwise specified, the following% and parts represent% by weight and parts by weight, respectively.

[0025]

[Example 1] [Preparation of multi-layered acrylic polymer] In a pressure reactor equipped with a stirring blade having an internal volume of 250 liters, 150 liters of ion-exchanged water and 620 g of sodium dihexylsulfosuccinate as an emulsifier were placed and heated to 75 ° C with stirring. It was heated and dissolved uniformly. Innermost hard layer material MMA23.8kg, BA1
500 g and 7 kg of a monomer mixture consisting of 25.3 g of ALMA were added all at once to the polymerization reactor, and 5 minutes later, 5 g of ammonium persulfate was added to carry out the polymerization reaction at 75 ° C. After 40 minutes, the remaining monomer mixture was continuously fed to the polymerization reactor over 20 minutes, and after the addition was completed, a further 6
Hold for 0 minutes to complete the reaction.

Next, after adding 23 g of ammonium persulfate, 23.1 kg of BA, 5.0 kg of St, which are the raw materials for the soft layer,
A monomer mixture consisting of 600 g of ALMA and 60 g of PEGDA was continuously added to the polymerization reactor over 140 minutes, and after the addition was completed, the polymerization was further continued for 180 minutes to complete the reaction. Next, after adding 7 g of ammonium persulfate, the outermost hard layer raw material MMA 15.9 kg, BA101
A monomer mixture consisting of 0 g and 17.0 g of n-OM was continuously added to the polymerization reactor over 40 minutes, and after the addition was completed, the reaction was continued for another 60 minutes to complete the polymerization.

A small amount of the latex thus obtained was sampled, and the average particle size was measured by absorptiometry to find that it was 0.23 μm. The remaining latex was put into a 3 wt% sodium sulfate aqueous solution heated to 95 ° C. to salt out and coagulate, then dehydration and washing were repeated 3 times and then dried to obtain a multi-layered acrylic polymer (A-1). ) White powder was obtained. [Preparation and Evaluation of Acrylic Resin Composition] This polymer (A-
1) 60 parts by weight of MMA / MA copolymer (B-1) [M
MA / MA = 88/12 weight ratio in chloroform, 25
The reduced viscosity at C was 43 g / ml] 40 parts by weight, glycerin monostearate 2 parts by weight, and HMBT 0.1 part by weight as an ultraviolet absorber were mixed for 2 minutes with a Henschel mixer, and then a vent with a screw diameter of 30 mm was used. Using an attached twin-screw extruder, granulation was performed at 260 ° C. to prepare an acrylic resin composition.

A predetermined test piece was prepared from the obtained pellet by injection molding, and its physical properties were measured. The haze was 1.2% and the Izod impact strength was 4.2 kg-cm / c.
m, and the tensile elongation was 20%. Almost no discoloration was observed by the weather resistance test, and haze after exposure was 2.
It was 5%, and the increase in haze was small. Further, when the releasability was evaluated, the defect occurrence rate was 2% (bending), and no clouding occurred on the mold surface. The results are shown in Table 1.
Summarized in.

[0029]

Example 2 Example 1 was repeated except that the amount of glycerin monostearate added when preparing the acrylic resin composition was 0.2 part by weight. The results are shown in Table 1.

[0030]

Comparative Example 1 The procedure of Example 1 was repeated, except that glycerin monostearate, which was added when the acrylic resin composition was prepared, was not added. When the releasability of the obtained resin composition was evaluated, the defective rate was 67% (whitening, bending), and many defective demolding occurred. Fogging on the surface of the mold did not occur.

The results are summarized in Table 1.

[0032]

Comparative Example 2 Except that the amount of glycerin monostearate added when preparing the acrylic resin composition was 8 parts by weight,
It carried out like Example 1. When a predetermined test piece was prepared from the obtained pellets by injection molding, the haze was slightly large, 2.3%. When the releasability of this resin composition was evaluated, the defect occurrence rate was 0%, which was extremely good, but cloudiness on the mold surface occurred. When the amount of the additive is excessive or inferior, it is considered that the additive adheres to the surface of the mold and fogging occurs.

The results are summarized in Table 1.

[0034]

[Example 3] [Preparation of multi-layered acrylic polymer] To a pressure reactor equipped with a stirring blade and having an inner volume of 250 liters, 150 liters of ion-exchanged water and 1 kg of sodium dioctylsulfosuccinate as an emulsifier were put, and the temperature was raised to 75 ° C with stirring. It was heated and dissolved uniformly. After adding 1.5 g of ammonium persulfate as an initiator, MMA6390 g of the innermost hard layer polymer raw material, BA4
A monomer mixture consisting of 10 g and ALMA 6.8 g was added, and a polymerization reaction was performed at 75 ° C. The reaction was completed about 20 minutes after the addition. Next, ammonium persulfate 13.8
g, and then 33.3 kg of BA as the raw material for the soft layer polymer, A
A monomer mixture consisting of 1080 g of LMA and 167 g of PEDGA was continuously supplied to the polymerization reactor over 2 hours, and the polymerization reaction was performed at 75 ° C. for about 90 minutes to complete the reaction. Next, MMA of the raw material of the first stage of the outermost hard layer
A monomer mixture consisting of 12,500 g and BA800 g was mixed with 3
It was continuously fed to the polymerization reactor over 0 minutes, and the polymerization reaction was carried out at 75 ° C. for another 20 minutes to complete the reaction. Finally, MMA12500g of the raw material of the second outermost hard layer,
A monomer mixture consisting of 800 g of BA and 40 g of n-OM was continuously fed to the polymerization reactor over 30 minutes,
The polymerization reaction was carried out at 75 ° C. for another 20 minutes to complete the reaction. The average particle size of the obtained latex sample was measured and found to be 0.08 μm.

The remaining latex was post-treated in the same manner as in Example 1 to obtain a white powder of a multi-layer structure acrylic polymer (A-2). In order to examine the molecular weight of each stage of the outermost hard layer, a 2 liter separable flask equipped with a stirrer was used to emulsion-polymerize the monomer mixture of the outermost hard layer 1 and the second stage raw material, respectively. The same post-treatment was performed to obtain a polymer corresponding to each stage as a white powder.
According to these GPC measurements, the weight average molecular weight of the polymer corresponding to the first stage of the outermost hard layer was 1,220,000, and the weight average molecular weight of the polymer corresponding to the second stage was 90,000. [Preparation of acrylic copolymer] MMA 66.8% by weight,
To a monomer mixture consisting of 3.2% by weight of MA and 30% by weight of EB, 300 ppm of DBPMS and n-OM2 were added.
000 ppm was added and mixed uniformly. This solution was continuously supplied to a closed pressure-resistant reactor having an internal volume of 10 liters, polymerized with stirring at an average temperature of 130 ° C. and an average residence time of 2 hours, and then continuously sent out to a storage tank to evaporate volatile components under reduced pressure. Was removed and further transferred continuously to the extruder to obtain pellets. This is referred to as an acrylic copolymer (B-2). The reduced viscosity of this copolymer was 36 ml / g. The composition of this copolymer was analyzed by a pyrolysis gas chromatography method, and a result of MMA / MA = 95.5 / 4.5 (weight ratio) was obtained. (Note) Pyrolysis gas chromatography method Dichloromethane solution of polymer is cast on platinum boat.
Dry and 450 ° C in a pyrolysis furnace (PYR-2A made by Shimadzu)
Then, the decomposed gas components were immediately introduced into a gas chromatography column and analyzed. The results were quantitatively calculated using the polymer analysis results of known composition obtained by bulk polymerization as a standard. [Preparation and Evaluation of Acrylic Resin Composition] The same procedure as in Example 1 was carried out. The results are summarized in Table 1.

[0036]

[Comparative Example 3] (A-2) when preparing an acrylic resin composition
90 parts by weight, (B-2) 10 parts by weight, glycerin monostearate 0.5 parts by weight, and HMBT 0.1 parts by weight were mixed in a Henschel mixer for 2 minutes, and then a vent having a screw diameter of 30 mm was provided. Using a twin-screw extruder, 25
The same procedure as in Example 3 was carried out except that an acrylic resin composition was prepared by granulating at 0 ° C.

A slight yellowing was observed in the weather resistance test, and the haze after exposure was increased to 6.5%. Furthermore, when the releasability was evaluated, the defect occurrence rate was 40% (bending)
And so many mold release defects occurred. Also, the surface of the mold was slightly fogged. The results are summarized in Table 1.

[0038]

[Comparative Example 4] (A-2) when preparing an acrylic resin composition
25 parts by weight, 75 parts by weight of (B-2), 0.5 parts by weight of glycerin monostearate, and 0.1 parts by weight of HMBT were mixed for 2 minutes in a Henschel mixer, and then with a vent having a screw diameter of 30 mm. Using a twin-screw extruder, 25
The same procedure as in Example 3 was carried out except that an acrylic resin composition was prepared by granulating at 0 ° C.

The haze was 1.0%, indicating excellent transparency, but the Izod impact strength was slightly insufficient at 2.5 kg-cm / cm, and the tensile elongation was small at 10%.
The results are summarized in Table 1.

[0040]

[Example 4] [Preparation of multi-layered acrylic polymer] In a pressure reactor equipped with a stirring blade and having an inner volume of 250 liters, 150 liters of ion-exchanged water and 500 g of sodium dioctylsulfosuccinate as an emulsifier were put, and the temperature was raised to 80 ° C with stirring. It was heated and dissolved uniformly. After adding 34 g of sodium formaldehyde sulfoxylate as a reducing agent, MMA5280 g, BA66 g, ALMA 5.3 g of the innermost hard layer polymer raw material,
A monomer mixture consisting of 5.3 g of DPBHP and DPBHP was added, and a polymerization reaction was carried out at 80 ° C. The reaction was completed about 20 minutes after the addition. Next, after adding 28 g of sodium formaldehyde sulfoxylate, BA3 as the soft layer polymer raw material was added.
9 kg, St 9.1 kg, ALMA 190 g, PEDG
A monomer mixture consisting of 1160 g of A and 48 g of DPBHP was continuously fed to the polymerization reactor over 2 hours,
The polymerization reaction was carried out at 0 ° C. for a further 90 minutes to complete the reaction. Next, MMA5280 as a raw material for the first stage of the outermost hard layer
g, 64 g of BA, and 5.3 g of DPBHP were continuously supplied to the polymerization reactor over 30 minutes, and the polymerization reaction was performed at 80 ° C. for another 20 minutes to complete the reaction. Finally, M of the second raw material of the outermost hard layer
MA10600g, BA128g, DPBHP10.7
g and n-OM 32 g monomer mixture was continuously fed to the polymerization reactor over 30 minutes and further 2 minutes at 80 ° C.
The polymerization reaction was performed for 0 minutes to complete the reaction. When the average particle size was measured using the obtained latex sample, it was 0.11 μm.

The remaining latex was post-treated in the same manner as in Example 1 to obtain a white powder of a multi-layer structure acrylic polymer (A-3). In order to examine the molecular weight of each stage of the outermost hard layer, a 2 liter separable flask equipped with a stirrer was used to emulsion-polymerize the monomer mixture of the outermost hard layer 1 and the second stage raw material, respectively. The same post-treatment was performed to obtain a polymer corresponding to each stage as a white powder.
According to these GPC measurements, the weight average molecular weight of the polymer corresponding to the first stage of the outermost hard layer was 1,260,000, and the weight average molecular weight of the polymer corresponding to the second stage was 100,000. [Preparation and Evaluation of Acrylic Resin Composition] This polymer (A-
3) 50 parts by weight of MMA / MA copolymer (B-3) [M
MA / MA = 97/3 weight ratio, in chloroform, 25 ° C.
Reduced viscosity is 54 g / ml] 50 parts by weight, glycerin monostearate 1 part by weight, and HMBT 0.1
After mixing 2 parts by weight in a Henschel mixer for 2 minutes,
Using a twin-screw extruder with a vent having a screw diameter of 30 mm, granulation was performed at 260 ° C to prepare an acrylic resin composition. The results are summarized in Table 1.

[0042]

Comparative Example 5 100 parts by weight of the copolymer (B-3) of Example 4, 0.05 parts by weight of glycerin monostearate, and 0.1 parts by weight of HMBT were mixed for 2 minutes with a Henschel mixer, and then the screw diameter was 30 mm. Was pelletized at 220 ° C. using a vented twin-screw extruder to prepare an acrylic resin composition.

A test piece was prepared from the obtained pellets by injection molding, and its physical properties were measured. The haze was 0.3%.
It showed excellent transparency, but the Izod impact strength was 1.
It was as low as 2 kg-cm / cm and the tensile elongation was as small as 6%. Almost no discoloration due to weather resistance test,
The haze after exposure was also small, 0.5%. Further, when the releasability was evaluated, the defective occurrence rate was 7%.
As a result of (cracks), fogging on the surface of the mold did not occur.

[0044]

[Table 1]

[0045]

EFFECTS OF THE INVENTION The composition of the present invention has excellent moldability due to its low adhesion to metal, and has impact resistance and impact resistance while maintaining transparency and weather resistance which are the original features of acrylic resin. Since it has an excellent tensile elongation, it can be suitably used for producing an injection-molded article, an extrusion sheet or a profile extrusion-molded article having a good appearance, particularly a film.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a molded product that is molded to evaluate releasability in an example of the present invention.

Claims (1)

[Claims] 1. A multi-layered acrylic polymer (A) 45 to 8
0 parts by weight, (B) methyl methacrylate unit 80 to 99
% By weight and 1 to 20% by weight of an alkyl acrylate unit having an alkyl group with 1 to 4 carbon atoms, and a reduced viscosity measured at 25 ° C. in chloroform of 30 to 120 g /
The carbon number is 1 to 100 parts by weight of 20 to 55 parts by weight of acrylic copolymer and 100 parts by weight of (A) and (B).
An acrylic resin composition comprising 0.01 to 5 parts by weight of at least one glycerin ester of saturated fatty acid of 4 to 20.