JPS6327516A - Highly weather-and impact-resistant acrylic resin granular composite material - Google Patents

Abstract

PURPOSE:The titled composite material, consisting of a five-layered structure in which each layer is constituted of (meth)acrylic acid based monomer of specific composition, capable of holding the transparency and fluid moldability, having remarkably improved impact as well as weather resistance and useful as molded articles for outdoor use. CONSTITUTION:A granular composite material of a five-layered structure consisting of the innermost layer as the first layer and the outermost layer as the fifth layer and constituted of the first layer consisting of a copolymer, consisting of methyl methacrylate or a blend thereof with a comonomer and a polyfunctional graft monomer and having >=25 deg.C glass transition temperature (Tg), the second layer consisting of a copolymer, consisting of a monomer blend containing an alkyl acrylate, polyethylene glycol diacrylate and polyfunctional graft monomer, and having <=25 deg.C Tg, the third layer consisting of a copolymer consisting of the monomer blend in the second layer and methyl methacrylate, etc., and having >=25 deg.C Tg, the fourth layer consisting of a polymer, consisting of methyl methacrylate, etc., and having >=25 deg.C Tg and the fifth layer consisting of methyl methacrylate, etc., and having 60,000-250,000 molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to impact resistant acrylic resin composites with improved properties. More specifically, the present invention not only has the excellent transparency and flow molding processability inherent to acrylic resins, but also has significantly improved impact resistance and weather resistance, and is highly weather resistant and impact resistant, suitable for outdoor use. This invention relates to a synthetic acrylic resin composite.

Conventional technology Acrylic resins are widely used both indoors and outdoors due to their excellent transparency, weather resistance, beautiful appearance, and ease of molding.However, acrylic resins generally do not have sufficient impact strength. There was a strong demand for improvements.

Conventionally, attempts have been made to introduce elastomers that exhibit rubber properties at room temperature into acrylic resins as a general and effective method to improve the impact resistance of acrylic resins. A method is used in which a saturated rubber-like elastic material, a saturated rubber-like elastic material whose main components are n-butyl acrylate and 2-ethylhexyl acrylate, is dispersed in the form of particles.

However, the introduction of such an unsaturated rubber-like elastic material impairs the weather resistance, which is a characteristic of acrylic resin, so in recent years, introduction of a saturated rubber-like elastic material has been considered from the viewpoint of weather resistance. The introduction of a saturated rubber-like elastic material has low elastic properties and low graft polymerizability with hard resins, so it impairs the impact resistance, transparency, gloss, and other appearance of acrylic resins, and also Since it is necessary to increase the content, there are problems such as a decrease in flow processability. In order to solve these problems, for example, a blend of a three- or four-layer resin composite and a hard thermoplastic polymer has been developed to improve impact resistance without sacrificing transparency. 27576), has a three-layer structure,
In addition, the structure has an intermediate layer having a concentration gradient that changes at a nearly constant rate between each of these layers, and has improved stress whitening resistance against impact (Japanese Patent Laid-Open Nos. 51-129449 and 53-58554). Although these methods are certainly effective in improving stress whitening resistance, they are not necessarily satisfactory in terms of impact resistance, and in addition, long-term outdoor exposure There was a problem in that the impact resistance strength was inevitably reduced.

Therefore, as a further improvement method, a part of the rubber elastic layer and hard resin layer are overlapped to form a two-layer structure (Japanese Patent Laid-Open No.
No. 43444), 6-layer structure (U.S. Pat. No. 4.475)
．． 679 specification) or a four-layer structure (Japanese Patent Application Laid-open No. 1983-
202213) proposed to improve the impact resistance by forming a granular material.

Problems to be Solved by the Invention As described above, in order to maintain the favorable properties of acrylic resins and improve other disadvantages, it has been proposed to form granular composites with many multilayer structures. However, satisfactory results regarding weather resistance have not yet been obtained. In particular, it is recognized that the initial values of impact resistance and other mechanical strength of the granular composite with the above-mentioned four-layer structure are considerably improved before outdoor exposure, but the weather resistance after long-term outdoor exposure is The improvement in sex was not yet fully satisfactory.

The purpose of the present invention is to improve the drawbacks of such conventional acrylic resin granular composites, and to improve impact resistance and weather resistance in addition to the excellent transparency and flow moldability inherent to acrylic resins. It is an object of the present invention to provide a granular acrylic resin composite that is significantly improved.

Means for Solving the Problems As a result of intensive research into improving the weather resistance of impact-resistant acrylic resin composites, the present inventors discovered that each layer is composed of a copolymer of a specific composition. It was discovered that the above object could be achieved by forming a granular composite with a layered structure, and based on this knowledge, the present invention was completed.

That is, the present invention provides an acrylic resin granular composite having a five-layer structure in which the innermost layer is the first layer and the outermost layer is the fifth layer.
The glass transition point ('Pg
) Copolymer at 25°C or higher, the second layer is made of an ethylenically unsaturated monomer mixture containing at least 50% by weight of alkyl acrylate, polyethylene glycol diacrylate with a degree of polymerization of 1 to 25, and a polyfunctional graft monomer. The resulting copolymer with a glass transition point ('I'g) of 25°C or less, the third
When forming the second layer, the layer contains a monomer mixture left unreacted in the range of 15 to 30% by weight and methyl methacrylate or an ethylenically unsaturated monomer mixture containing at least 50% by weight of methyl methacrylate. The copolymer is obtained from a glass transition point ('I'g) that gradually changes from the inside to the outside from a composition with a glass transition point ('I'g) of 25°C or lower to a composition of 25°C or higher, and the fourth layer is methyl methacrylate or make it at least 50
A polymer or copolymer with a glass transition point (Tg) of 25°C or higher obtained from a mixture of ethylenically unsaturated monomers including a weight range, and the fifth layer is methyl methacrylate or at least 50% of it.
% by weight of a polymer or copolymer having a molecular weight of 6o, ooo to 250,000 obtained from an ethylenically unsaturated monomer mixture containing granules of highly weather-resistant and impact-resistant acrylic resin. It provides a complex.

The impact-resistant acrylic resin granular composite of the present invention is produced by a four-step polymerization process, and it is preferable to use an emulsion polymerization method as the polymerization method.

That is, the first layer of the granular composite of the present invention is formed by copolymerizing an ethylenically unsaturated monomer mixture containing at least 50% by weight of allyl methacrylate or methyl methacrylate with a polyfunctional graft monomer. can be formed. Here, the ethylenically unsaturated monomer is a copolymerizable monomer having one ethylenically unsaturated bond, and examples of monomers other than methyl methacrylate include, for example, 2 carbon atoms.
Examples include alkyl methacrylates having ~4 alkyl groups, alkyl acrylates having 1 to 8 carbon atoms, acrylonitrile, allyl methacrylates, and the like.

When these are used in combination with methyl methacrylate, it is necessary to use them in an amount not exceeding 50% by weight based on the total amount of monomers, preferably in an amount of 20% by weight, and the larger the amount, the lower the transparency. do.

On the other hand, the polyfunctional graft monomer to be copolymerized with this ethylenically unsaturated monomer is a monomer that has two or more terminal ethylenically unsaturated groups with different reactivities and can be graft copolymerized. Examples of such substances include allyl methacrylate, allyl acrylate, vinyl methacrylate, and vinyl acrylate. These polyfunctional graft monomers may be used alone or
Also, two or more types may be used in combination.

The polyfunctional graft monomer is preferably used in a proportion of 5 or less, based on the total amount of the monomer mixture. If this amount exceeds 5% by weight, stress whitening resistance tends to decrease.

Copolymerization of these monomers can be carried out by introducing the monomers little by little into an aqueous medium containing an emulsifier and a catalyst while stirring the monomers, and allowing the reaction to occur. .

The first layer copolymer thus formed has a viscosity of 1
The glass transition point (Tg) expressed as the temperature at which tan δ peaks in dynamic viscoelasticity measurements conducted under conditions of 10 cps and a heating rate of 2° C./min is 25° C. or higher;
Preferably, the temperature needs to be 50°C or higher. When the glass transition point is less than 25° C., a material with low stress whitening resistance and low heat resistance is obtained.

The second layer in the granular composite of the present invention comprises an ethylenically unsaturated monomer mixture containing at least 50% by weight of alkyl acrylate, polyethylene glycol diacrylate having a degree of polymerization of 1 to 25, and a polyfunctional graft monomer. It consists of a copolymer with a glass transition point of 25° C. or lower obtained by copolymerization with

The alkyl acrylate mentioned above is preferably an alkyl acrylate in which the alkyl group has 1 to 8 carbon atoms, particularly ethyl acrylate and n-butyl acrylate. These may be used alone or in combination of two or more.

In addition, as the ethylenically unsaturated monomer used in combination with this, among the monomers having one ethylenically unsaturated bond, in particular, by matching the refractive index with a hard polymer obtained mainly from methyl methacrylate, , aromatic monomers such as styrene and styrene derivatives, which can improve transparency, are preferred. These may be used alone or in combination of two or more.

Next, as the polyethylene glycol diacrylate, one having a degree of polymerization, that is, a repeating number of units represented by -CH2CH20-, is in the range of 1 to 25, preferably 2 to 14. This polyethylene glycol diacrylate is used to impart weather resistance to the copolymer, and may be used alone or in combination of two or more. Further, as the polyfunctional graft monomer, the same ones as in the case of the copolymer of the first layer are used, such as allyl methacrylate, allyl acrylate, vinyl methacrylate,
Vinyl acrylate and the like are used. These may be used alone or in combination of two or more.

Regarding the usage ratio of each component to obtain the second layer polymer, the alkyl acrylate is 50 to 95% by weight, preferably 80 to 85% by weight, and the ethylenically unsaturated monomer used in combination with this is 50 to 95% by weight. It is preferable that the proportion of polyethylene glycol diacrylate is 0.1 to 15 weight % and the polyfunctional graft monomer is 5 weight % or less. This second layer copolymer needs to have a glass transition point of 25°C or lower, preferably 0°C or lower. When this Tg exceeds 25°C, impact resistance decreases.

When forming the second layer, the third layer in the granular composite of the present invention contains 15 to 15% of the total amount of the monomer mixture for forming the second layer.
Glass transition point obtained by copolymerizing an unreacted monomer mixture remaining in a proportion of 30% by weight with methyl methacrylate or an ethylenically unsaturated monomer mixture containing at least 50% by weight of methyl methacrylate. It consists of a copolymer with a structure in which the composition gradually changes from the inside to the outside from the composition below 25°C to the composition above 25°C.

This third layer copolymer is added to methyl methacrylate or methyl methacrylate when the polymerization conversion rate reaches 70 to 85% by weight, preferably 75 to 80% by weight in forming the second layer. It is obtained by continuously feeding and polymerizing an ethylenically unsaturated monomer mixture containing at least 50% by weight ffi, preferably at a rate slightly higher than the polymerization rate. Changes in the composition of the third layer polymer can be easily determined by quantitatively analyzing the remaining monomer mixture using gas chromatography or the like. If the copolymerization of the third layer copolymer is started outside the polymerization conversion range of the second layer polymer, impact resistance and weather resistance cannot be significantly improved.

At this time, as the ethylenically unsaturated monomer used in combination with methyl methacrylate, the same monomers as those used in the production of the first layer copolymer can be used alone or in combination of two or more. .

The copolymers of the first layer, second layer, and sixth layer are thought to have a three-dimensional crosslinked structure due to a crosslinking reaction based on the polyfunctional graft monomer and polyethylene glycol diacrylate. It will be done.

The fourth layer in the granular composite of the present invention is obtained by homopolymerizing or copolymerizing methyl methacrylate or an ethylenically unsaturated monomer mixture containing at least 50% by weight of methyl methacrylate, and has a glass transition point of 25°C or higher. The preferred polymer or copolymer is methyl methacrylate.
0 or more and other ethylenically unsaturated monomers 20% by weight
It is a copolymer with: If the proportion of methyl methacrylate is less than 50% by weight, it is not preferable because transparency will be impaired. At this time, examples of the ethylenically unsaturated monomer used in combination with methyl methacrylate include those used in forming the first layer, and these monomers may be used alone or Two or more types may be used in combination.

The glass transition point of the fourth layer copolymer needs to be 25°C or higher, preferably 50°C or higher; if it is lower than 25°C, the heat resistance will be poor.

The fifth layer in the granular composite of the present invention is a copolymer having a glass transition point of 25°C or higher obtained by polymerizing or copolymerizing methyl methacrylate or an ethylenically unsaturated monomer mixture containing at least 50% by weight of methyl methacrylate. Copolymerizable monomer 2, preferably 80% by weight or more of methyl methacrylate and other copolymerizable monomers
It consists of a copolymer with 0% by weight or more. In this case, as the ethylenically unsaturated monomer used in combination with methyl methacrylate, the same monomers as those used in the first layer copolymer can be used alone or in combination of two or more.

In forming this fifth layer copolymer, the molecular weight is controlled by adding a chain transfer agent from the viewpoint of fluid moldability, and the molecular weight is adjusted to 60.000 to 250.000, preferably 80.000. It is necessary to adjust it within the range of 000 to 200.000. If the molecular weight is less than 60,000, mechanical strength including impact resistance will be low; If the ODD is exceeded, flow molding processability decreases. Examples of chain transfer agents used in this case include alkyl mercaptans, thioglycolic acid, and thioglycolic acid esters.

The glass transition point of the fifth layer copolymer needs to be 25°C or higher, preferably 50°C or higher; if it is lower than 25°C, the heat resistance will be poor.

The weight ratio of each layer in the granular composite of the present invention is as follows:
Based on the total amount of the polymer, the first layer is 20 to 40% by weight, the second layer is 20 to 50% by weight, the third layer is 5 to 40% by weight, the fourth layer is 20% by weight or more, and the fifth layer is 20 to 40% by weight. is preferably in the range of 5 to 20% by weight. Polymers in which the weight ratio of each layer is outside the above range may have insufficient weather resistance, extremely low impact resistance or other mechanical strength, or may cause problems in the post-polymerization treatment process, resulting in insufficient weight. This may lead to undesirable situations such as not being able to combine.

A more preferable weight ratio is 30 to 40% by weight of the first layer;
The second layer is 60 to 40% by weight, the sixth layer is 5 to 30% by weight,
The fourth layer is 10% by weight or more and the fifth layer is in the range of 5 to 15% by weight.

Advantageously, the appropriate polymerization temperature for forming each layer of polymer or copolymer is between 30 and 120 degrees Celsius for each step.
C1 is preferably selected in the range of 50 to 100C. Furthermore, in order to form such a multilayered composite, it is possible to form a particulate multilayered composite by sequentially adding and reacting each monomer or monomer mixture.
It is advantageous to use so-called seed polymerization methods. At this time, when polymerizing the second and subsequent layers, it is necessary to select conditions that will prevent the formation of new particles, but this can be achieved by reducing the amount of emulsifier used below the critical micelle concentration. can. The presence or absence of new particle generation can be confirmed by observing with a quantum microscope.

There are no particular restrictions on the emulsifier used in emulsion polymerization, and any emulsifier can be selected from conventionally used emulsifiers, such as long-chain alkyl carboxylates, sulfosuccinic acid alkyl ester salts, alkylbenzene sulfonates, etc. Can be mentioned.

These emulsifiers have a particle size (hereinafter referred to as final particle size) of the granular composite after the final fifth layer is formed between 0.2 and 0.
．． It is used in an amount of 8 μm, preferably 0.3 to 0.35 μm. When the amount of emulsifier used is lower than the critical micelle concentration, the concentration of emulsifier and the polymer latex produced (these are spherical and have a particle size distribution of 1.0 to 1.0 mm).
Since there is a simple one-to-one correspondence between the number of grains (which has been confirmed by electron microscopy to be about 2), the particle size can be estimated from this relationship. In addition, by actually measuring the absorbance of polymer latex with known particle sizes using an electron microscope (measurement wavelength: 550 nm; latex temperature 50 ppm), a calibration curve was created from the absorbance for polymer latex of various particle sizes. The final particle size of the particulate five-layer polymer was measured using the same.

The final particle size of the particulate 5-layer 114 copolymer is 0.2 μm
If it is less than 0.8 μm, not only the impact resistance will be reduced, but also the effective expression of weather resistance will be impaired, and if it exceeds 0.8 μm, transparency and flow molding processability will be reduced.

There are no particular restrictions on the polymerization initiator used at this time, and commonly used water-soluble inorganic initiators such as persulfates and perborates may be used alone, or sulfites and thiosulfates may be used. It can also be used in combination with a redox initiator system. Additionally, redox initiator systems such as oil-soluble organic peroxides/ferrous salts, organic peroxides/sodium formaldehyde sulfoxylates can also be used.

The granular composite with a five-layer structure obtained by such a polymerization method can be obtained as a granular solid by performing treatments such as salting out, separation, washing, and drying from the state of polymer latex using known methods. .

The highly weather resistant and impact resistant acrylic polymer of the present invention can be injection molded or extrusion molded as it is or after being pelletized to obtain a desired molded product. It can also be used by blending it with commonly used acrylic resin molding materials. The blending ratio at this time is appropriately selected depending on the purpose of use. The acrylic resin molding material to be blended may be obtained by any known polymerization method, such as bulk polymerization, suspension polymerization, emulsion polymerization, or solution polymerization. It is done in the same way.

In addition to the resin, commonly used additives such as ultraviolet absorbers, antioxidants, dyes and pigments can be added as necessary.

The polymer thus obtained has excellent flow molding processability, and the molded product obtained by injection molding or extrusion molding has excellent transparency and impact resistance, and also exhibits high weather resistance.

Example Next, the present invention will be explained in more detail with reference to Examples.

Note that measurements in Examples and Comparative Examples were performed using the following methods or measuring instruments.

I zod impact strength: ASTM D256 Flowability (M
FI): ASTM D1238 (230°C, 3.
819 load) Light transmittance: ASTM D1003 Final particle size: Measured by turbidity method using absorption intensity at 550 nm (Shimadzu spectrophotometer UV-120) Weather resistance: Sunshine weather meter (Suga Test Instruments)
Sunshine Super Long Life Weather Meter manufactured by Co., Ltd.: WEL-3UN-H
IZO (l impact strength (ASTM D256)) was measured after exposure for 2000 hours by C). In addition, the abbreviations in Examples and Comparative Examples indicate the following compounds.

MMA: Methyl methacrylate BA: n-butyl acrylate St: Styrene MA: Methyl acrylate ALMA: Allyl methacrylate PE0DA: Polyethylene glycol diacrylate (degree of polymerization n = 1 to 14) NPG: 2,2-dimethyl- 1,3-butanediol-dimethacrylate TAIC: Triallyl isocyanurate n-0M: n-
Octylmercaptan HMBT: 2-(2'-Hydroxy-5'-methylphenyl)hensotriazole Example 1 101! Place 75 liters of ion-exchanged water in a reaction vessel equipped with a reflux condenser.
0C1yl, sodium dihexyl sulfosuccinate 1'0.9 were added, and the temperature was raised to 7Q'c under a nitrogen stream while stirring at a rotational speed of 2501 Tom, and 2 g of ammonium persulfate was added under a state without the influence of oxygen.
MMA 650J, BA 9g, HMBTO, 2
A monomer mixture consisting of 60 g and 0.07 g of ALMA
The mixture was added continuously over a period of minutes, and after the addition was completed, the temperature was maintained for an additional 30 minutes. The copolymer thus produced as the innermost first layer was dispersed in the form of particles as latex.

Then, in the presence of this particulate polymer, BA77Q9,
St 150 g,) IMB'I' 0.3 J,
ALMA 3,7, lit and PEGDA (n
= 14) 85 monomer mixture consisting of 22 jp
It was added continuously over a period of minutes, and after the addition was completed, it was held for 30 minutes to form a second layer. The polymerization conversion rate at this time was about 80%.

At this point, MMA 280.91BA2g and HMB
A monomer mixture consisting of TOoll was added continuously over a period of 40 minutes, and after the addition was completed, the temperature was maintained for about 1 hour until the temperature in the reaction vessel due to the heat of polymerization rose to the initial set temperature. During this time, all the remaining components of the monomer mixture for forming the second layer polymer are consumed in about 30 minutes, and at this point, MM
As a result of analysis by gas chromatography, it was found that the polymerization conversion rate of the monomer mixture consisting of A, BA and HMBT was about 50%. Therefore, up to this point, the actual third layer was formed, and after this point, the actual fourth layer was formed.

Next, MMA 280! j, BA 2nd evening, HMB
T O,1ji and n -OM O as chain transfer agent
, 9/l was added continuously over a period of 20 minutes, and after the addition was completed, the temperature was maintained for about 1 hour until the temperature in the reaction vessel due to the heat of polymerization reached the initial set temperature, and then the reaction was continued. The system was heated to 95° C. to complete polymerization and form the fifth layer. At this stage, the produced copolymer was dispersed in the form of particles, and microscopic observation revealed that it was an acrylic polymer with a 5-layered particulate structure having a spherical shape and a uniform particle size.

In this polymer, the Tg of each of the innermost first layer, fourth layer, and fifth layer was approximately 100°C as a result of measurement, and the Tg of the second layer polymer was -5 to - 10℃ 1st 3rd
The average Tg of the layer polymer was approximately 50°C.

The latex thus obtained was poured into a 5% by weight warm aqueous solution of sodium sulfate to cause salting out and coagulation, followed by repeated dehydration and water washing, followed by drying. The molecular weight of the fifth layer polymer is approximately 120,000 from the results of viscosity and viscosity measurements.
Met.

57.5 parts by weight of this five-layer structured polymer and 42.5 parts by weight of a granular copolymer consisting of 99% by weight of MMA units obtained by normal suspension polymerization and 1 weight of MA single unit were placed in a Henschel mixer. After mixing for 20 minutes at
The pelletization was carried out at 40°C.

The portions within the fourth layer were not melted and destroyed.

The pellet was molded at 250°C using an in-line screw injection molding machine [Toshiba Machine (Yanagi Seiko S-753 model)].
1. Create test pieces for each physical property test under the conditions of injection pressure 900 kgf / 2 and mold temperature 50 ° C.
Physical properties were measured. The obtained resin composition had excellent weather resistance, flow moldability, and transparency.

Example 2 In Example 1, PE0DA (n = 2) was used as a polyfunctional crosslinkable monomer to form the second layer polymer.6.
Example 1 was carried out in exactly the same manner as in Example 1, except that 61 was used.

Example 3 In Example 1, PBODA (n = 4) was used as a polyfunctional crosslinkable monomer to form the second layer polymer.9.
The experiment was carried out in exactly the same manner as in Example 1 except that 4I was used.

Example 4 In Example 1, PEGDA (n = 9)15.
It was carried out in exactly the same manner as in Example 1 except that 8 g was used.

Example 5 Polymerization was carried out in exactly the same manner as in Example 1, except that 10 g of sodium dioctyl sulfosuccinate was used instead of sodium dihexyl sulfosuccinate.

Example 6 In Example 1, MMA17 was used to form the fifth layer polymer.
0,! 9, BA 17. HMB'[' 0.06J
and n-01J O,54I.
It was carried out in exactly the same manner as in Example 1, except that the addition was carried out continuously over a period of 0 minutes.

Example 7 In Example 1, MMA22 was used to form the fifth layer polymer.
0 p, IBA I, 5 fl, HMB'r 010
8,! ? Example 1, except that the monomer mixture was added continuously over 15 minutes from 0,72 g of n −0 M
It was carried out in exactly the same manner.

The physical property evaluation of the test pieces in these Examples is shown in the attached table.

Comparative Example 1 A comparative example was carried out in exactly the same manner as in Example 1, except that the formation of the fifth layer polymer was omitted.

Comparative Example 2 In Example 1, MMA18 was used to form the fifth layer polymer.
80 I! , BA 15.4 g, HMBT o,y
A monomer mixture consisting of g and n-0M61
It was carried out in exactly the same manner as in Example 1 except that the addition was carried out continuously over a period of minutes.

Comparative Example 3 In Example 1, PE0DA was used to form the second layer polymer.
(n = 14) (7) It was carried out in exactly the same manner as in Example 1, except that 7.5 g of NPC was used instead.

Comparative Example 4 In Example 1, PEGDA was used to form the second layer polymer.
The experiment was carried out in exactly the same manner as in Example 1, except that TAIC7,7,lit was used instead of (n=14).

Comparative Example 5 In Example 1, BA770 was used to form the second layer polymer.
．． 9. St 150.9. FIMBTO O, 3, 9
, ALMA 5.7 g and PRlODA (n = 1
4) A monomer mixture consisting of 22 fi was added continuously over 85 minutes, and after the addition was completed, the temperature in the reaction vessel due to the heat of polymerization was maintained until it reached the initial setting, and then the third layer was added. The procedure was carried out in exactly the same manner as in Example 1 except that the polymerization was started.

Comparative Example 6 570 ml of ion-exchanged water was placed in a reaction vessel with a 10/2 reflux condenser.
18 g of sodium dioctyl sulfosuccinate was added, and the temperature was raised to 70°C under a nitrogen stream while stirring at a rotation speed of 25 Orpm to avoid the influence of oxygen.
Add ammonium persulfate 2I, then MMA 66
A monomer mixture consisting of 0 J, BA 9 J, 0.21 HMB'l' and 7 fl of ALMA O was added continuously over 50 minutes and then held for 30 minutes. The produced copolymer was dispersed as a latex in the form of particles.

Subsequently, in the presence of this particulate polymer, BA 77Q9
, St 190 J, HMB'r O03fi and P
A monomer mixture consisting of 23 g of EGDA (n=14) was added continuously over 60 minutes and held for 20 minutes after the addition was complete.

The polymerization conversion rate at this time was 80.

At this point, MMA 290.9. A monomer mixture consisting of BA 21/ and HMBTOolg was added continuously over 40 minutes, and after the addition was completed, the mixture was maintained for about 1 hour until the temperature in the reaction vessel due to the heat of polymerization reached the initial setting.

Next, MMA 570 ji, BA 4
A monomer mixture consisting of 9 and HMBT O,2N was
It was added continuously over a period of minutes, and after the addition was completed, the mixture was added with the heat of polymerization.

The temperature rise in the reaction vessel will take approximately 1 hour until the temperature rises to the initial set temperature.
The temperature was maintained for a certain period of time, and then the temperature of the reaction system was raised to 95° C. to complete the polymerization. At this stage, the produced copolymer was dispersed in the form of particles, and microscopic observation revealed that it was a granular composite with an approximately spherical shape and uniform particle size.

Next, the same treatment as in Example 1 was performed to prepare a test piece.

The physical property evaluation of the test pieces in these comparative examples is shown in the following table.

Effects of the Invention The highly weather-resistant and impact-resistant acrylic resin granular composite of the present invention has a five-layer structure, and compared to the conventional impact-resistant acrylic resin granular composite, the soft rubber component (the five layers Despite the low content of the second-layer polymer in the structural polymer, it has significantly improved impact resistance, excellent weather resistance, and is as transparent as regular acrylic resin. Since it has excellent flow molding processability, it is particularly suitable as a material for acrylic resin molded products for outdoor use.

Claims (1)

[Scope of Claims] 1. An acrylic resin granular composite having a five-layer structure in which the innermost layer is the first layer and the outermost layer is the fifth layer, wherein the first layer is methyl methacrylate or at least 50% by weight thereof. A copolymer having a glass transition point (Tg) of 25° C. or higher obtained from an ethylenically unsaturated monomer mixture and a polyfunctional graft monomer, the second layer containing at least 5 alkyl acrylates.
The glass transition point (T
g) Copolymer at 25°C or lower, the third layer is a monomer mixture that remained unreacted in the range of 15 to 30% by weight during the formation of the second layer and methyl methacrylate or at least 50% of methyl methacrylate. weight%
A copolymer obtained from an ethylenically unsaturated monomer mixture containing, and whose composition gradually changes from the inside to the outside from a composition with a glass transition point (Tg) of 25°C or lower to a composition with a glass transition temperature (Tg) of 25°C or higher, 4 layers contain methyl methacrylate or at least 50% of it
A polymer or copolymer having a glass transition point (Tg) of 25° C. or higher obtained from a mixture of ethylenically unsaturated monomers containing methyl methacrylate or at least 50% by weight of the fifth layer.
% by weight of a polymer or copolymer having a molecular weight of 60,000 to 250,000 obtained from an ethylenically unsaturated monomer mixture. complex. 2 1st layer 20-40% by weight, 2nd layer 20-50% by weight
, a weight ratio in the range of 5 to 40% by weight for the third layer, 20% by weight for the fourth layer, and 5 to 20% by weight for the fifth layer, and 0.2 to 0.8.
A highly weather-resistant and impact-resistant acrylic resin granular composite according to claim 1, having a particle size in the range of μm.