JPH1171437A - Acrylic multi-layer granular composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic polymer which shows excellent transparency, antiweatherability, formability, shock resistance, resistance to stress whitening, resistance to warm water whitening, thermal stability and the like and is useful for manufacture of formed products such as a film, etc., and a laminated composite. SOLUTION: The acrylic multi-layer granular composite having a 3 layer structure comprises an innermost layer of a hard polymer (a) obtained by polymerizing of monomers comprised of 80-98.99 wt.% of MMA, 1-20 wt.% of alkylacrylate(AA) having 1-8 carbon atoms in an alkyl group, 0.01-1 wt.% of a polyfunctional grafting agent and 0-0.5 wt.% of a polyfunctional crosslinking agent, a soft layer of a polymer (b) obtained by polymerizing of monomers comprised of 70-99.5 wt.% of AA having 1-8 carbon atoms in an alkyl group, 0-30 wt.% of MMA, 0.5-5 wt.% of a polyfunctional grafting agent and 0-5 wt.% of a polyfunctional crosslinking agent in the presence of the polymer (a) and an outermost layer of a hard polymer (c) having a glass transition temperature of not less than 80 deg.C obtained by polymerizing of monomers comprised of 90-99 wt.% of MMA and 10-1 wt.% of AA in the presence of particles of the polymers (a) and (b). An average diameter of the particles is 0.01-0.3 μm and its melt flow rate at 230 deg.C and under a load of 3.8 kg is 0.5-20 g/10 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an acrylic multi-layered granular composite, an agglomerated granular body comprising the same, a method for producing the same, a molded article comprising the acrylic multi-layered granular composite or agglomerated granular body, and a laminate. It is about the body. The acrylic multi-layer structure granular composite of the present invention and the aggregated granular material comprising the same have excellent moldability, laminate moldability, and thermal stability, and the molded articles and laminates obtained therefrom have impact resistance. Transparency, stress whitening resistance, hot water whitening resistance, excellent thermal stability, etc., therefore, acrylic multi-layered granular composite of the present invention and its aggregated particulate,
Utilizing these characteristics, it can be effectively used for various molded articles and laminates including films, sheets and plates.

[0002]

2. Description of the Related Art Acrylic resin has a beautiful appearance,
It has high transparency, is extremely excellent in weather resistance, and can be easily subjected to injection molding, extrusion molding, and other melt molding. Used. However, the acrylic resin has insufficient impact resistance, and when stress is applied, cracks and chips are likely to occur. Attempts have also been made to use acrylic resins, which have excellent transparency and weather resistance, for the production of thin materials such as films and sheets.However, such thin materials have low strength, are extremely brittle, and are practical films. And sheets cannot be obtained.

Therefore, in order to improve the above-mentioned drawbacks of the acrylic resin, attempts have been made to improve the impact resistance by introducing a rubber component and to improve the strength of a thin material such as a film. However, in the case of the prior art, poor appearance due to reduced transparency,
A significant decrease in weather resistance due to the introduced rubber component is likely to occur, and an acrylic resin material having transparency, weather resistance and impact resistance has not yet been obtained.

In particular, in order to obtain an acrylic resin which can be used for the production of a thin material such as a film, there have been proposed various alkyl methacrylate polymer multilayer particles containing an acrylic rubber layer and polymer compositions containing the same. . All of them aim at improving impact resistance, and for that purpose, a method is employed in which polyalkyl acrylate having a low glass transition point is used as a nucleus, and then methyl methacrylate and alkyl acrylate are added in a divided manner and polymerized.
As a result, although thin materials such as films can be molded, the outstanding transparency inherent in acrylic resins is impaired, and molded products generally have a bluish translucent or cloudy (haze) shape. . In addition, when a sheet or a film is bent, the bent portion is whitened, and so-called "stress whitening" occurs, which greatly restricts practical use.

[0005] The prior art relating to alkyl methacrylate-based polymer multilayer granules containing a rubber layer is specifically exemplified as follows.
For example, U.S. Pat. No. 3,450,632 and U.S. Pat. No. 3,562,235 disclose an elastic polymer whose main component is a polyalkyl acrylate in order to improve impact resistance. Are described, but these materials are not sufficiently satisfactory in terms of thermal stability, stress whitening, and the like.

A multilayer granular polymer having a core of a hard resin mainly composed of methyl methacrylate or styrene has also been proposed. For example, JP-B-46-3591 discloses that an inner layer (core) and an outer layer are formed of methyl methacrylate. And / or a three-layer granular polymer formed from a hard resin containing styrene as a main component and having a crosslinked polyalkyl acrylate layer disposed therebetween. However, in this three-layered granular polymer, the graft bond between the layers is not sufficient, so that a molded article obtained by using the three-layered granular polymer is translucent or opaque and has a large stress whitening. When a stress such as bending or stretching is applied, whitening is apt to occur, and the characteristics inherent to the methyl methacrylate resin are lost. In addition, the three-layered granular polymer cannot have a large molding width at the time of molding a thin material such as a film, and lacks suitability as a material for a thin material such as a film.

Further, Japanese Patent Publication No. 55-27576 discloses polymethyl methacrylate, polystyrene and polymethyl methacrylate for the purpose of obtaining a low-haze, impact-resistant polymer composition.
There has been proposed a polymer composition in which a hard thermoplastic polymer such as polyacrylonitrile is blended with a three-layered granular polymer having a layer constitution similar to that described in JP-B-46-3591. I have. However,
Thin molded articles such as films and sheets obtained using this polymer composition have the inherent drawback of a polymer blend system in that bending and whitening easily occur, and are translucent or opaque and transparent. It is significantly inferior to polymethyl methacrylate and polystyrene in terms of properties.

Japanese Unexamined Patent Publication (Kokai) No. 7-223298 discloses a three-layer granular polymer having a layer constitution similar to that described in Japanese Patent Publication No. 46-3591 and a hard thermoplastic acrylic resin. A laminate is described in which a layer of the blend is laminated on a polycarbonate resin substrate. The three-layered granular polymer used in the laminate has an elastic polymer layer mainly composed of a lower alkyl acrylate between the inner and outer layers having a high glass transition point.
It is stated that the impact-resistant composition can be obtained by blending the three-layered granular material with a hard thermoplastic acrylic resin. However, the three-layered granular material has extremely poor fluidity, and therefore has poor moldability by itself, and cannot be used alone for producing thin molded articles such as films. Moreover, the blend comprising the three-layered granular material and the hard thermoplastic acrylic resin is an essential drawback of the polymer blend system.
There is a problem that bending whitening tends to occur as described above, and a disadvantage that transparency is poor.

Further, Japanese Patent Publication No. 52-30996,
JP-B-63-42940, JP-B-7-68318
JP-A-5-320457 has a layer structure similar to the three-layer granular polymer described above, and particularly, a lower alkyl acrylate and styrene such as styrene between the inner layer and the outer layer having a high glass transition point. A three-layer granular polymer having an intermediate layer of an elastic polymer formed from a monomer mixture with an aromatic vinyl compound is described. The three-layer granular polymer is transparent by adjusting the refractive index of each layer. Attempts have been made to retain sex. However, in this three-layered granular polymer, the elastic polymer constituting the intermediate layer has a structural unit derived from an aromatic vinyl compound such as styrene, so that the weather resistance is low and the molding of a thin material such as a film. Poor applicability as a material of the product.

Further, Japanese Patent Publication No. 58-1694 and Japanese Patent Publication No. 59-366455 have a three-layer structure and further provide an intermediate layer having a concentration gradient which varies at a substantially constant rate between the respective layers. A multi-layered granular polymer having four or more layers is described. Furthermore, Japanese Patent Publication No. 59-36646
JP-A-63-8983 and JP-B-63-8983 describe a granular polymer having a multilayer structure of four or more layers which further has one or more intermediate layers between a central soft polymer layer and an outermost layer. Japanese Patent Publication No. 62-41241 discloses a soft layer.
A multi-layered granular polymer having four or more layers such as a hard layer-a soft layer-a hard layer is described. However,
Since these multi-layered granular polymers are all multilayers having a total of four or more layers, the polymerization process for obtaining the multi-layered granular polymer requires a complicated and long polymerization time,
Poor productivity.

Further, the acrylic resin has a relatively large hygroscopicity, and easily absorbs and whitens when immersed in warm water or when the temperature rises after rain when used outdoors. In particular, in the case of thin molded articles such as films, the above-mentioned hot water whitening phenomenon leads to a decrease in transparency, greatly impairing the commercial value. As measures to prevent hot water whitening, conventionally, a hydrophobic monomer such as cyclohexyl methacrylate is copolymerized in an acrylic resin, or a water-repellent and / or hydrophobic compound such as a silicone compound or a plasticizer is converted to an acrylic resin. Methods have been attempted to reduce the absorption of warm water by adding it to the resin, but none of these methods has yielded satisfactory results.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to maintain the properties inherent to acrylic resins, such as good moldability, beautiful appearance, high transparency, and excellent weather resistance, and to obtain other thermoplastic resins. Even if not blended with polymers or elastic polymers, it has excellent impact resistance and thermal stability by itself, thereby avoiding deterioration in transparency and weather resistance caused by blending with other polymers While itself, it manufactures various molded products and laminates with excellent appearance, transparency, weather resistance, stress whitening resistance, hot water resistance, heat stability, etc. with good moldability, smoothly and with good productivity To provide an acrylic-based multi-layered granular composite that can be used. An object of the present invention is to obtain an acrylic-based multi-layered granular composite having the above-described excellent properties by a simple polymerization step and a processing step without requiring a complicated and time-consuming polymerization step or a processing step. That is. It is a further object of the present invention to provide a molded article and a laminate comprising the acrylic-based multilayer composite having excellent characteristics described above.

[0013]

Means for Solving the Problems The present inventors have intensively studied to achieve the above object. Each of the innermost layer and the outermost layer is made of a specific hard polymer mainly composed of methyl methacrylate, and has a soft polymer layer mainly composed of a specific lower alkyl acrylate in the middle thereof, and the innermost layer, the intermediate layer and A three-layer granular polymer containing the outermost layer in a specific ratio and having a specific average particle size and a specific melt flow rate was successfully produced. When the physical properties of the three-layered granular polymer thus obtained were examined in various ways, the three-layered granular polymer was found to have good moldability, heat stability, beautiful appearance, and excellent appearance inherent to acrylic resins. It has excellent properties such as transparency and weather resistance, and has excellent impact resistance, stress whitening resistance, hot water whitening resistance, etc. by itself without blending with other thermoplastic polymers or elastic polymers. Appearance, transparency, weather resistance, stress whitening resistance, hot water whitening by itself without causing a decrease in transparency or weather resistance caused by blending with other polymers. sex,
It has been found that molded articles and laminates having excellent thermal stability and the like can be produced with good moldability and high productivity. In particular, the above-mentioned acrylic multi-layered granular composite produced by the present inventors has good moldability to a thin molded article such as a film,
It has been found that the film and the like obtained thereby have excellent appearance, transparency, impact resistance, etc., do not whiten even when subjected to stress such as bending or stretching, and do not whiten when exposed to warm water.

Further, the present inventors have studied the above-obtained 3
The layered granular polymer is agglomerated to have an average particle size of 100 to 5
When the agglomerated granules having a thickness of 00 μm, an apparent density of 0.3 g / cm ³ or more, and a compression ratio of less than 30% are obtained, the agglomerated granules obtained thereby are less likely to be scattered, and are excellent in handleability and moldability. Extrusion molding and injection molding etc. can be performed smoothly, good dispersibility of other additives in agglomerated granules, no blocking or adhesion to equipment during handling and storage, and It has been found that a molded article obtained by using the aggregated granules does not generate bumps (fish eyes) and has excellent mechanical properties, and the present invention has been completed based on these various findings.

That is, the present invention relates to an acrylic multi-layered granular composite; (I) the acrylic multi-layered granular composite comprises: (i) 80 to 98.9% by weight of methyl methacrylate; 1 to 20% by weight of at least one alkyl acrylate having a number of 1 to 8; 0.01 to 1% by weight of a polyfunctional grafting agent;
An innermost layer hard polymer (a) obtained by polymerizing a monomer mixture comprising 0.5% by weight; (ii) an alkyl group having 1 carbon atom in the presence of the innermost layer hard polymer (a). At least one of alkyl acrylates having a molecular weight of 0 to 8; 70 to 99.5% by weight of methyl methacrylate;
A soft layer polymer (b) obtained by polymerizing a monomer mixture consisting of 5% by weight and a polyfunctional crosslinking agent of 0 to 5% by weight; and (iii) the innermost layer hard polymer (a) and a soft layer polymer. In the presence of polymer particles consisting of the layer polymer (b), at least one of an alkyl acrylate having 90 to 99% by weight of methyl methacrylate and an alkyl group having 1 to 8 carbon atoms is used.
An outermost layer hard polymer (c) having a glass transition point of 80 ° C. or higher obtained by polymerizing a monomer mixture comprising 0 to 1% by weight; and having a three-layer structure; 5-30% by weight of the above innermost layer hard polymer (a) based on the weight of the composite,
20 to 45% by weight of the soft layer polymer (b) and 50 to 75% by weight of the outermost hard polymer (c); (III) the average particle size is 0.01 to 0.3 μm; And (IV) a melt flow rate under a load of 3.8 kg at 230 ° C. of 0.5 to 20 g / 10 min.

Further, the present invention provides an agglomerated granular material obtained by aggregating the above-mentioned acrylic multi-layered granular composite,
Average particle size is 100 to 500 µm, apparent density is 0.3 g
/ Cm ³ or more and a compression ratio of less than 30%.

Further, the present invention provides a molded article comprising the above-mentioned acrylic multi-layered granular composite and / or the above-mentioned agglomerated granular body, and a molded article comprising the above-mentioned acrylic multi-layered granular composite and / or the above-mentioned agglomerated granular body. And a laminate having at least one layer formed of another thermoplastic polymer as well as at least one layer formed of another thermoplastic polymer.

The present invention relates to (1) 80 to 99.99% by weight of methyl methacrylate and at least one alkyl acrylate having 1 to 8 carbon atoms in the alkyl group.
-20% by weight, polyfunctional grafting agent 0.01-1% by weight
And a monomer mixture comprising 0 to 0.5% by weight of a polyfunctional crosslinking agent is polymerized in an aqueous medium to produce a hard polymer,
(2) In an aqueous medium in the presence of the hard polymer obtained in the polymerization step (1), at least one kind of alkyl acrylate having an alkyl group having 1 to 8 carbon atoms is 70 to 99.5.
%, 0 to 30% by weight of methyl methacrylate, 0.5 to 5% by weight of a polyfunctional grafting agent and 0 of a polyfunctional crosslinking agent.
To 5% by weight of a monomer mixture to produce polymer particles comprising a soft polymer laminated on the hard polymer, and (3) a polymer particle obtained in the polymerization step (2). In the presence of the coalesced particles, a monomer mixture comprising 90 to 99% by weight of methyl methacrylate and 10 to 1% by weight of at least one alkyl acrylate having 1 to 8 carbon atoms in an aqueous medium is polymerized. Forming a layer of a hard polymer having a glass transition point of 80 ° C. or higher on the soft polymer, and based on the total weight of the monomers used for producing the acrylic multi-layered granular composite, The proportion of the monomer mixture used in the polymerization step (1) is 5 to 30% by weight, the proportion of the monomer mixture used in the polymerization step (2) is 20 to 45% by weight, and the polymerization step ( The above simple substance used in 3) Wherein the ratio of the mixture is 50 to 75 wt%, is a manufacturing method of the acrylic multi-layer particulate composite of the present invention described above.

The present invention provides an aqueous dispersion containing the above-mentioned acrylic multi-layered granular composite of the present invention,
Then, after melting it, it is dehydrated and dried to have an average particle size of 100 to 500 μm and an apparent density of 0.3 g / cm.
This is a method for producing an aggregated granular material of the acrylic multi-layered granular composite according to the present invention, which has a compression ratio of ³ or more and a compression ratio of less than 30%.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The acrylic multi-layered granular composite of the present invention comprises an innermost layer (core) composed of the innermost hard polymer (a), an intermediate layer composed of the soft layer polymer (b) and an outermost layer hard polymer (c).
This is a three-layered granular material composed of: The innermost layer hard polymer (a) in the acrylic-based multilayer composite of the present invention is:
As mentioned above, methyl methacrylate 80-99.99
%, At least 1 to 20% by weight of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, 0.01 to 1% by weight of a polyfunctional grafting agent, and 0 of a polyfunctional crosslinking agent.
It is obtained by polymerizing a monomer mixture consisting of .about.0.5% by weight.

The alkyl acrylate having an alkyl group having 1 to 8 carbon atoms (hereinafter referred to as "C _1-8 alkyl acrylate") used for forming the innermost layer hard polymer (a) includes C _{1-8 of} acrylic acid. Any alkyl ester may be used without particular limitation, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate,
n-butyl acrylate, s-butyl acrylate, t
-Butyl acrylate, n-butylmethyl acrylate, n-heptyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, and the like. One or more of these alkyl acrylates can be used. Among them, methyl acrylate and / or n-butyl acrylate are preferably used.

The polyfunctional grafting agent used for forming the innermost layer hard polymer (a) chemically bonds the innermost layer hard polymer (a) and the soft layer polymer (b). To form a crosslinked structure in the innermost hard polymer (a). As the polyfunctional grafting agent, any polyfunctional monomer having the above-mentioned function can be used, and generally, a compound having two or more different polymerizable groups is preferably used. Specific examples of the multifunctional grafting agent include allyl methacrylate, allyl acrylate, mono- or di-allyl maleate, mono- or di-allyl fumarate, crotyl acrylate, crotyl methacrylate, and the like. Of 1
Species or two or more can be used. Among them, allyl methacrylate is the innermost layer hard polymer (a)
It is preferably used because it has a high binding ability between the polymer and the soft layer polymer (b) and is excellent in stress whitening resistance and transparency.

Further, the polyfunctional crosslinking agent is used to form a crosslinked structure in the innermost hard polymer (a) at the time of polymerization and to prevent the acrylic multi-layered granular composite from being broken at the time of molding. This polyfunctional cross-linking agent is an optional component used as needed in forming the innermost layer hard polymer (a). As the polyfunctional crosslinking agent, any polyfunctional monomer capable of forming a crosslinked structure in the innermost layer hard polymer (a) during polymerization can be used. For example, a diacryl compound, a dimethacryl compound, a diallyl compound Conventionally known polyfunctional crosslinking agents such as divinyl compounds and trivinyl compounds can be used. More specifically, for example, ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, divinylbenzene, trivinylbenzene, ethylene glycol diallyl Examples thereof include ether and propylene glycol diallyl ether, and one or more of these can be used.

In the acrylic multi-layered granular composite of the present invention, the innermost hard polymer (a) is based on the total weight of the monomer mixture used to form the innermost hard polymer (a). 80 to 9 of methyl methacrylate
8.99% by weight, 1 to 20% by weight of at least one of _C1-8 alkyl acrylates, and 0.1 to 0.1% of a polyfunctional grafting agent.
It needs to be formed by polymerization of a monomer mixture containing 0.1 to 1% by weight and a polyfunctional crosslinking agent in a ratio of 0 to 0.5% by weight, and methyl methacrylate 90 to 9
Monomer consisting of 6.9% by weight, 3-10% by weight of _C1-8 alkyl acrylate, 0.1-0.5% by weight of polyfunctional grafting agent and 0-0.2% by weight of polyfunctional crosslinking agent It is preferably formed by polymerization of the mixture.

If the proportion of methyl methacrylate is less than 80% by weight, based on the total weight of the monomer mixture used for producing the innermost layer hard polymer (a), the weather resistance tends to decrease, while 98.99. If the content exceeds 10% by weight, the impact resistance tends to decrease. Further, if the proportion of the _C1-8 alkyl acrylate is less than 1% by weight based on the total weight of the monomer mixture used for producing the innermost layer hard polymer (a), the acrylic multi-layered granular composite may be thermally degraded. Easy to decompose, while 20% by weight
Exceeding the temperature will cause the hot water whitening of a molded article such as a film obtained from the acrylic-based multi-layered granular composite to be remarkable. Also,
Based on the total weight of the monomer mixture used in the production of the innermost hard polymer (a), the proportion of the polyfunctional grafting agent is 0.0
When the amount is less than 1% by weight, the bond between the innermost layer hard polymer (a) and the soft layer polymer (b) is weakened, and the acrylic multi-layered granular composite is easily broken at the time of molding. %, The impact resistance of the acrylic-based multi-layered granular composite decreases. Further, since the innermost layer hard polymer (a) is also crosslinked to some extent by the polyfunctional grafting agent as described above, it is not always necessary to use the polyfunctional crosslinking agent. Is required to be 0.5% by weight or less based on the total weight of the monomer mixture used for forming the innermost hard polymer (a).
If the amount is more than 10% by weight, the crosslinking of the innermost layer hard polymer (a) becomes excessive and the impact resistance decreases.

The intermediate layer composed of the soft layer polymer (b) in the acrylic multi-layered granular composite of the present invention comprises:
In the presence of the innermost layer hard polymer described above (a), based on the total weight of the monomer mixture used for the production of soft layer polymer (b), 70 to at least one C _{1 to 8} alkyl acrylates 99.5% by weight, 0 to 3 of methyl methacrylate
It must be formed by polymerizing a monomer mixture containing 0% by weight, 0.5 to 5% by weight of a polyfunctional grafting agent and 0 to 5% by weight of a polyfunctional crosslinking agent. And 90 to 99% by weight of at least one of C _1-8 alkyl acrylate and 0 to 99% of methyl methacrylate.
It is preferably formed by polymerizing a monomer mixture containing 10% by weight, 1 to 3% by weight of a polyfunctional grafting agent and 0 to 2% by weight of a polyfunctional crosslinking agent.

C _1-8 used for producing the soft layer polymer (b)
As the alkyl acrylate, one or more of the same alkyl acrylates as those described above for the C _1-8 alkyl acrylate used in the production of the innermost layer hard polymer (a) can be used. Methyl acrylate and / or n-butyl acrylate are preferably used. As the polyfunctional grafting agent used for producing the soft layer polymer (b), the same polyfunctional grafting agent as described above for the polyfunctional grafting agent used for producing the innermost layer hard polymer (a) is used. One or more of the hydrophilic grafting agents can be used, and among them, allyl methacrylate has high binding ability between the soft layer polymer (b) and the outermost layer hard polymer (c), and has a high resistance to stress whitening. It is preferably used because of its excellent transparency. The polyfunctional cross-linking agent used as needed in the production of the soft layer polymer (b) includes the innermost layer hard polymer (a)
One or more of the same polyfunctional compounds as those described above for the polyfunctional crosslinking agent that can be used for the production of the compound (I) can be used.

If the proportion of the C _1-8 alkyl acrylate is less than 70% by weight based on the total weight of the monomer mixture used for producing the soft layer polymer (b), the impact resistance tends to decrease. On the other hand, when it exceeds 99.5% by weight, stress whitening resistance and transparency tend to decrease. Further, if the proportion of methyl methacrylate exceeds 30% by weight based on the total weight of the monomer mixture used for producing the soft layer polymer (b), the impact resistance tends to decrease. This methyl methacrylate is an optional component used as needed, and need not always be used. If the proportion of the polyfunctional grafting agent is less than 0.5% by weight based on the total weight of the monomer mixture used for producing the soft layer polymer (b), the acrylic multi-layered granular composite may have The resulting molded article such as a film or the like or the laminate has reduced stress whitening resistance, whereas if it exceeds 5% by weight, the impact resistance of the acrylic multi-layered granular composite decreases. Furthermore, since the soft layer polymer (b) is crosslinked to some extent by the polyfunctional grafting agent without using the polyfunctional crosslinking agent, the polyfunctional crosslinking agent is an optional component used as necessary. Although it is not necessary to use the polyfunctional crosslinking agent, it is necessary to use 5% by weight or less based on the total weight of the monomer mixture used to form the soft layer polymer (b). If it exceeds 5% by weight, the impact resistance of the acrylic-based multi-layered granular composite decreases.

The outermost layer hard polymer (c) in the acrylic multi-layered granular composite of the present invention is a polymer particle comprising the innermost layer hard polymer (a) and the soft layer polymer (b). presence in, it is necessary that it is formed by polymerizing a monomer mixture consisting of at least one 10 to 1 wt% of methyl methacrylate 90 to 99 wt% and C _{1 to 8} alkyl acrylates, methyl methacrylate it is preferably formed by polymerizing a monomer mixture consisting of 95 to 98 wt% and at least one 5 to 2% by weight of C _{1 to 8} alkyl acrylate. Further, the outermost layer hard polymer (c) needs to have a glass transition point of 80 ° C. or higher, and preferably 90 ° C. or higher.

The proportion of methyl methacrylate is less than 90% by weight, based on the total weight of the monomer mixture used for producing the outermost hard polymer (c) (the proportion of C _1-8 alkyl acrylate is 10% by weight). ), The glass transition point of the outermost layer hard polymer (c) tends to be lower than 80 ° C., and the stress whitening resistance of a molded article such as a film or a laminate obtained from an acrylic multilayer granular composite is low. It will be. On the other hand, based on the total weight of the monomer mixture used for producing the outermost layer hard polymer (c), the proportion of methyl methacrylate exceeds 99% by weight (the proportion of _C1-8 alkyl acrylate is less than 1% by weight. ), The acrylic multi-layered granular composite is likely to be thermally decomposed.

C used for producing the outermost layer hard polymer (c)
_{As the 1-8} alkyl acrylate, one or more of the same alkyl acrylates as described above for the C _1-8 alkyl acrylate used in the production of the innermost layer hard polymer (a) can be used. Of these, methyl acrylate and / or n-butyl acrylate are preferably used.

In the acrylic multi-layer structure particulate composite of the present invention, the innermost layer hard polymer (a) is 5 to 30% by weight, and the soft layer weight is based on the weight of the acrylic multi-layer structure granular composite. It is necessary to have 20 to 45% by weight of the combined polymer (b) and 50 to 75% by weight of the outermost hard polymer (c).
-20% by weight, 30-40% by weight of the soft layer polymer (b)
And it is preferable to have 50-60 weight% of the outermost layer hard polymer (c). When the proportion of the innermost layer hard polymer (a) in the acrylic multilayer structure granular composite is less than 5% by weight, the thermal stability of the acrylic multilayer structure granular composite decreases, and the innermost layer hard polymer (a ), The polymerization reaction (that is, seed polymerization) for forming the soft layer polymer (b) is not smoothly performed. On the other hand, if the ratio of the innermost layer hard polymer (a) exceeds 30% by weight, the impact resistance and flexibility of the acrylic-based multi-layered granular composite deteriorate. Further, when the ratio of the soft layer polymer (b) in the acrylic multi-layered granular composite is less than 20% by weight, the impact resistance and flexibility of the acrylic multi-layered granular composite are reduced, while 45% by weight is reduced. If the amount exceeds the above range, the heat resistance and the fluidity of the acrylic-based multi-layered granular composite decrease. If the proportion of the outermost layer hard polymer (c) in the acrylic multi-layered granular composite is less than 50% by weight, the flowability and film forming property of the acrylic multi-layered granular composite are reduced, while 75% by weight. If it exceeds 300, the impact resistance and the stress whitening resistance of the acrylic-based multi-layered granular composite decrease.

The average particle size of the acrylic multi-layered granular composite of the present invention must be in the range of 0.01 to 0.3 μm, preferably 0.04 to 0.2 μm. , 0.05 to 0.15 μm. If the average particle size of the acrylic multi-layered granular composite is less than 0.01 μm, it is necessary to increase the polymer concentration in the system in order to improve the productivity, in which case the aqueous dispersion used in the polymerization The viscosity becomes too high, and the handleability decreases. On the other hand, when the average particle size of the acrylic-based multilayer composite has a particle size of more than 0.3 μm, the stress whitening resistance of a molded article such as a film or a laminate obtained therefrom is reduced. The average particle size of the acrylic multilayer structure granular composite referred to in the present specification is determined by an absorbance method using an aqueous dispersion containing the acrylic multilayer structure granular composite as described in the section of Examples below. Value.

The acrylic multi-layered granular composite of the present invention must have a melt flow rate at 230 ° C. under a load of 3.8 kg of 0.5 to 20 g / 10 min. It is preferably 10 to 10 g / 10 minutes. When the melt flow rate of the acrylic multi-layered granular composite is less than 0.5 g / 10 min, the flowability is low and the moldability is poor. On the other hand, when the melt flow rate is higher than 20 g / 10 min,
The mechanical properties are inferior.

The method for producing the acrylic multi-layered granular composite of the present invention is not particularly limited, and any method can be used as long as it can produce the acrylic multi-layered granular composite having the above-mentioned requirements. You may. Among them, the acrylic-based multi-layered granular composite of the present invention comprises (1) 80 to 99.99% by weight of methyl methacrylate, and 1 to 20% by weight of at least one alkyl acrylate having 1 to 8 carbon atoms in an alkyl group. , Polyfunctional grafting agent 0.01-1
% By weight and a monomer mixture comprising 0 to 0.5% by weight of a polyfunctional crosslinking agent is polymerized in an aqueous medium to produce a hard polymer, and (2) the hard polymer obtained in the polymerization step (1) is obtained. At least one alkyl acrylate having an alkyl group having 1 to 8 carbon atoms in an aqueous medium in the presence of a polymer;
9.5% by weight, 0 to 30% by weight of methyl methacrylate,
Polymer particles obtained by polymerizing a monomer mixture comprising 0.5 to 5% by weight of a polyfunctional grafting agent and 0 to 5% by weight of a polyfunctional crosslinking agent and laminating a soft polymer on the hard polymer. And (3) in the presence of the polymer particles obtained in the polymerization step (2), 90-99% by weight of methyl methacrylate and an alkyl group having 1-99 carbon atoms in an aqueous medium.
At least one alkyl acrylate that is
1% by weight of a monomer mixture is polymerized to form a layer of a hard polymer having a glass transition point of 80 ° C. or higher on the soft polymer, and an acrylic multi-layered granular composite is produced. The proportion of the monomer mixture used in the polymerization step (1) is 5 to 3 based on the total weight of the monomers used in the polymerization.
0% by weight, the proportion of the monomer mixture used in the polymerization step (2) is 20 to 45% by weight, and the proportion of the monomer mixture used in the polymerization step (3) is 50 to 75% by weight. Can be produced smoothly by a multi-stage polymerization method. At that time, the above polymerization steps (1) to (3)
Is preferably carried out by emulsion polymerization. In particular, the polymerization step (2) and the polymerization step (3) are more preferably carried out by a general seed polymerization method.

Polymerization step for forming outermost layer hard polymer (c)
When performing (3), the melt flow rate of the acrylic-based multi-layered granular composite finally obtained is adjusted to 0.5 to 20 g / by adjusting the molecular weight of the polymer by adding a chain transfer agent. It can be in the range of 10 minutes. The kind of the chain transfer agent at that time is not particularly limited, and conventionally known ones can be used. Xanthogen disulfides such as dimethyl xanthogen disulfide and diethyl xanthogen disulfide; thiuram disulfides such as tetrathiuram disulfide; and halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide.
In general, the chain transfer agent is preferably used in a proportion of 0.05 to 2 parts by weight, preferably 0.08 to 1 part by weight, based on 100 parts by weight of the monomer mixture used in the polymerization step (3). It is more preferable to use.

In the above polymerization steps (1) to (3),
If agglomerates are generated during the polymerization or the deposits in the polymerization tank are mixed into the polymer, when a molded article such as a film is produced using the obtained acrylic-based multi-layered granular composite material, (Fish eye) occurs and the product value decreases. Therefore, it is important to carry out the polymerization steps (1) to (3) while suppressing the formation of aggregates, reducing the amount of deposits in the polymerization tank, and minimizing their incorporation into the polymer. . As a preferable method therefor, there may be mentioned a method in which the polymerization steps (1) to (3) are performed while supplying the monomer mixture dropwise to the polymerization system while adjusting the supply amount. The feed rate of the monomer mixture at that time is based on the total weight of the monomer mixture used in each polymerization step in each of the polymerization step (1), the polymerization step (2), and the polymerization step (3). It is preferable to carry out the polymerization in each step while controlling the supply ratio of the monomer mixture to each polymerization system at 0.05 to 3% by weight, and 0.1 to 1% by weight.
/ Min, more preferably from 0.2 to
More preferably, the supply rate is 0.8% by weight / minute.

The polymerization steps (1) to (3) are carried out by emulsion polymerization using a polymerization initiator, preferably in the presence of an emulsifier. The type of the polymerization initiator is not particularly limited, for example, potassium persulfate, a water-soluble inorganic initiator such as ammonium persulfate, a redox initiator using a sulfite or a thiosulfate in combination with the inorganic initiator, an oil. Soluble organic peroxide /
Redox initiators such as ferrous salts and organic peroxides / sodium sulfoxylates can be used. When the polymerization initiator radical amount in the polymerization system decreases,
The polymerization may be carried out while adding the polymerization initiator in a divided manner.

The type of emulsifier is not particularly limited, and can be arbitrarily selected from those conventionally used.
For example, anionic emulsifiers such as long-chain alkyl sulfonate, alkyl sulfosuccinate, and alkylbenzene sulfonate; nonionic emulsifiers such as polyoxyethylene alkyl ether and polyoxyethylene nonyl phenyl ether; polyoxyethylene nonyl phenyl ether sulfate Nonionic / anionic compounds such as polyoxyethylene nonyl phenyl ether sulfate such as sodium, polyoxyethylene alkyl ether sulfate such as sodium polyoxyethylene alkyl ether sulfate, and alkyl ether carboxylate such as sodium polyoxyethylene tridecyl ether acetate Emulsifiers can be mentioned.

The polymerization steps (1) to (3) may be performed in the same polymerization tank or in different polymerization tanks, but are preferably performed in the same polymerization tank. When the above-mentioned polymerization steps (1) to (3) are carried out by emulsion polymerization using an emulsifier, the type of the emulsifier, the amount of the emulsifier added, the concentration of the polymerization initiator, the polymerization temperature, etc. are finally adjusted. The average particle size of the obtained acrylic multi-layered granular composite can be adjusted to the above-mentioned range of 0.01 to 0.3 μm. Generally, it is preferable to carry out each of the polymerization steps (1) to (3) at a temperature of 30 to 120 ° C.
More preferably, it is carried out at a temperature of １００100 ° C.

In any of the polymerization steps (1) to (3), if necessary, a reactive ultraviolet absorber, for example, 2- [2-hydroxy-5- (2-methacryloyloxyethyl) phenyl] Polymerization may be performed by adding -2H-1,2,3-benzotriazole or the like to produce an acrylic multi-layered granular composite having excellent ultraviolet light resistance. In this case, the amount of the ultraviolet absorber is preferably about 0.05 to 5 parts by weight based on 100 parts by weight of the monomer mixture.

When aggregates are formed at any stage of the polymerization steps (1) to (3) or deposits (scales) are formed on the polymerization tank, the openings are 50 μm or less, preferably 30 μm. It is preferable to remove aggregates and scale using the following filter media.

After the completion of the above polymerization step (3), a dispersion is formed in which the acrylic multilayer particulate composite having an average particle size of 0.01 to 0.3 μm is dispersed in an aqueous medium. The method for separating and recovering the acrylic multilayer structure granular composite from the dispersion is not particularly limited, and may be performed by any method as long as the physical properties of the acrylic multilayer structure granular composite are not reduced. Freeze coagulation, salting out coagulation, acid precipitation coagulation,
It can be performed by a freeze drying method, a spray drying method, or the like.
In such a case, if the separated and collected acrylic-based multi-layered granular composite still contains moisture, it may be further dried to obtain a dry powder. In the case of freeze-drying or spray-drying, the average particle size is generally 0.01 to 0.3 as described above.
An acrylic multi-layered granular composite in the form of a dry powder in the range of μm is obtained, and when a freeze coagulation method, a salting out coagulation method, an acid precipitation coagulation method, or the like is used, generally, an acrylic multi-layered granular composite ( An aggregated granular material (secondary particle) in which a plurality of primary particles) are aggregated is obtained.

In the present invention, the freeze-coagulation method is preferably employed among the above-mentioned separation / recovery methods. In the case of the freeze-coagulation method, impurities contained in the acrylic-based multi-layered granular composite can be washed and removed, and the use of a coagulant such as a salting-out agent does not include a residue that causes coloring or the like. Acrylic multi-layered granular composites are obtained.
In addition, in the case of the freeze-coagulation method, a plurality of the acrylic-based multi-layered granular composites (primary particles) are aggregated, and the handleability,
Agglomerated granules (secondary particles) can be produced which are excellent in moldability, have no appearance of fish (fish eyes) when molded, and can provide molded articles having excellent mechanical properties.

When the freeze-coagulation method is used, the aqueous dispersion containing the acrylic-based multi-layered granular composite is cooled to -5 ° C.
A method of gradually freezing and coagulating over 30 minutes or more at the following temperature, then melting, dehydrating, and drying is preferably adopted, so that the average particle size is generally 100%.
Amorphous agglomerated particles (secondary particles) having an average density of about 500 μm, an apparent density of 0.3 g / cm ³ or more, and a compression ratio of less than 30% can be obtained. The agglomerated particles are less likely to be scattered, are excellent in handleability and moldability, are less likely to cause blocking during storage, are excellent in dispersibility when compounding additives, and are more difficult to obtain in molded articles obtained therefrom. (Fish eyes) do not occur and the mechanical properties are excellent. When the freeze-solidification is performed at a higher speed than described above, the average particle size of the aggregated granules becomes smaller than the above, and the aggregated granules are liable to be scattered and to have reduced handleability. Here, the average particle size, apparent density, and compression ratio of the aggregated granular material of the acrylic multilayer granular composite mean the values measured by the methods described in the following Examples.

The acrylic multi-layered granular composite of the present invention and the agglomerated granular body comprising the same can be melt-molded, and can be molded using a molding method and a molding apparatus generally used for thermoplastic polymers. In the form of powder, as it is, or in the form of pellets, for example, by extrusion molding, injection molding, blow molding, press molding, calendar molding, casting, melt lamination molding, etc., various molded products, for example , Films, sheets, plates, tubes, rods, and other three-dimensionally formed molded articles and laminates.

In particular, the acrylic multi-layered granular composite of the present invention and the agglomerated granular material comprising the same can be used for the production of thin molded articles such as films and sheets, which have been considered unsuitable for acrylic polymers. A thin molded article which is suitable and is obtained by using the acrylic multi-layered granular composite and / or agglomerated granular material of the present invention has excellent impact resistance, and also has excellent stress whitening resistance, and is whitened even when bent. Does not occur,
It has excellent hot water whitening resistance and does not cause whitening even when exposed to warm water. Conventionally known methods such as an extrusion molding method using a T-die and an inflation molding method can be employed in the production of thin molded articles such as films and sheets, and laminated films.

Furthermore, the acrylic multi-layered granular composite and aggregated granular material of the present invention may be used in combination with other polymers, especially polycarbonate polymers, vinyl chloride polymers, vinylidene fluoride polymers, methacrylic resins, ABS resins. , AES resin, AS resin, and the like, and have excellent adhesion to thermoplastic polymers. Therefore, the acrylic multi-layered granular composite of the present invention and / or the agglomerated granular material comprising the same and the thermoplastic polymer described above Using it, a laminated film or other laminated body can be manufactured smoothly. The method for producing the laminate at that time is not particularly limited, and for example, a method for producing a laminate by melt-coextrusion of the acrylic multi-layered granular composite or aggregated granular material of the present invention and the thermoplastic polymer described above, A method for producing a laminate by extrusion-coating the acrylic multi-layered granular composite or agglomerated granular material of the present invention on a film, sheet, plate or the like previously produced from a thermoplastic polymer, previously produced from a thermoplastic polymer A method for producing a laminate by introducing the acrylic multi-layered granular composite or agglomerated granular material of the present invention into a mold by injection molding or casting in a state where a film, a sheet, a plate, etc. are arranged in a mold, Examples of the method include a method of manufacturing a film, a sheet, a plate, and the like, which are preliminarily manufactured from a plastic polymer, and a method of press-molding the acrylic multi-layered granular composite of the present invention or an aggregated granular material thereof to produce a laminate. Kill.

The acrylic multi-layered granular composite of the present invention and the agglomerated granular body comprising the same may contain, if necessary, an ultraviolet absorber, an antioxidant, a light stabilizer, an antioxidant, a plasticizer, Known additives such as a molecular processing aid, a lubricant, a dye, and a pigment can be blended. The amount of these additives is used in a range that does not impair the object of the present invention, and is generally 0.01 to 2 parts by weight based on 100 parts by weight of the acrylic multi-layered granular composite or the aggregated granular material composed thereof.
It is used in the range of 0 parts by weight.

[0050]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto. "Parts" and "%" used in the following Examples and Comparative Examples indicate parts by weight and% by weight, respectively. The measurement and evaluation of various physical properties in Examples and Comparative Examples were performed as follows.

(1) Average particle size of acrylic multi-layered granular composite (granules before aggregation): An aqueous dispersion containing the acrylic multi-layered granular composite was collected, and the average particle size was determined by an absorbance method. Was.

(2) Average particle size of agglomerated granules composed of the acrylic-based multi-layered granular composite: The particles were sieved with an ASTM standard sieve, and the average particle size of the agglomerated granules was determined by the following equation using the weight average.

[0053]

## EQU00001 ## Average particle size of agglomerated granules = .SIGMA. (Yi.di / yi) where di is the mesh size (.mu.m) of the i-th sieve, and yi is i.
It shows the weight ratio of the powder remaining on the sieve of the stage.

(3) Apparent density of agglomerated granules of acrylic-based multi-granular composites: 10 apparent weights previously measured
In a 0 ml (100 cm ³ ) measuring cylinder [measuring cylinder weight W ₀ (g)], the aggregated granules are put up to a scale of about 50 ml, and the total weight (W) (g) of the measuring cylinder and the aggregated granules is measured. I do. After that, the operation (tapping) of dropping the measuring cylinder from a height of 10 cm is performed 10 times, and the volume (V) (ml = cm ³ ) of the aggregated granular material at that time is read on the scale of the measuring cylinder, and the following formula is used. The apparent density of the aggregated granules was calculated.

[0055]

## EQU2 ## Apparent density (g / cm ³ ) of aggregated granular material = (W
−W ₀ ) / V

(4) Pressurization and compression ratio of the aggregated granular material of the acrylic multi-layered granular composite: A cylindrical container [volume V ₀ (mm ³ )] having a diameter of 61 mm and a height of 80 mm is filled with the aggregated granular material. Then, from the top, a load of 0.3 kg / cm ² was averaged and pressed for 5 minutes, and the volume (V) (m
m ³ ) was measured, and the compression ratio of the aggregated granular material was calculated by the following equation.

[0057]

## EQU3 ## The compression ratio (%) of the agglomerated granular material = 体 (V ₀ −
V) / V ₀ ｝ × 100

(5) Melt flow rate: 230 ° C. according to ASTM-D1238, using pellets produced from agglomerated granules of the acrylic-based multi-granular composite.
Melt flow rate at 3.8 kg load (hereinafter "MF
R ") was measured.

(6) Thermal stability: The pellets produced from the aggregated granules of the acrylic multi-layered granular composite are kneaded at 280 ° C. for 5 minutes using a lab plast mill, and the state at that time is visually observed. The case where gelation and foaming did not occur was evaluated as good (良好), and the case where gelation and / or foaming occurred was evaluated as poor (×).

(7) Film formability: Using pellets composed of aggregated granules of an acrylic multi-layered granular composite,
Using a T-die extruder, cylinder temperature 250
℃, die temperature 240 ℃, die lip width 30
The film is melt-extruded through a T-die having 0 mm and a 0.3 mm gap between the upper and lower sides, and is drawn while being stretched 10 times in the longitudinal direction to produce a film. The minimum thickness of the film measured from 10 minutes to 60 minutes after the start of extrusion molding Sa (Dmin) (μm)
And the maximum thickness (Dmax) (μm), the thickness variation rate was determined by the following equation, and the film formability was evaluated according to the evaluation criteria shown in Table 1 below.

[0061]

## EQU4 ## Film thickness variation rate (%) = ｛(Dmax−Dm)
in) / Dmin｝ × 100

[0062]

[Table 1] [Evaluation criteria for film formability] A: The thickness variation is less than 5%, and the film formability is extremely good. ：: The thickness variation rate is 5 to 20%, and the film formability is almost good. X: The thickness variation exceeds 20%, and the film formability is poor.

(8) Laminating moldability: The laminate prepared by co-melt extrusion molding is visually observed to check for the presence of whitening at the flow mark and the layer interface. Good if not (○),
The case where whitening of the flow mark and / or the interface of the layer occurred was evaluated as defective (x).

(9) Impact resistance: A pellet consisting of agglomerated granules of an acrylic multi-granular structure composite was used, and an injection molding machine (“N70A” manufactured by Nippon Steel Works, Ltd.) was used. Injection pressure 100 kg / cm ² , mold temperature 6
Injection molding was performed under the condition of 0 ° C. to prepare a test piece.
Izod impact strength with V notch was measured according to STM-D256.

(10) Stress whitening resistance of a non-laminated molded product: An injection molding machine (“N70” manufactured by Nippon Steel Works, Ltd.)
A ") using a melting temperature of 250 ° C. and an injection pressure of 100
Injection molding was performed under the conditions of kg / cm ² and a mold temperature of 60 ° C. to prepare a dumbbell test piece for a tensile test, and using an autograph tensile tester (“AG-10TB” manufactured by Shimadzu Corporation) The test piece is stretched at a tensile speed of 5 mm / min,
The presence or absence of whitening at 10% elongation was visually observed, and evaluation was made as good (o) when whitening did not occur and as poor (x) when whitening occurred.

(11) Stress Whitening Resistance of Laminated Plate: A strip-shaped test piece having a width of 10 mm was cut out from a laminated plate having a thickness of 2 mm manufactured by co-melt extrusion molding, and was bent to 90 ° C. at normal temperature (20 ° C.). The presence or absence of whitening in the bent portion was visually observed, and evaluation was made as good (o) when whitening did not occur and as poor (x) when whitening occurred.

(12) Hot water whitening resistance of a non-laminated molded product: An injection molding machine (“N70” manufactured by Nippon Steel Works, Ltd.)
A ") using a melting temperature of 250 ° C. and an injection pressure of 100
Injection molding was performed under the conditions of kg / cm ² and a mold temperature of 60 ° C. to produce a 3 mm-thick plate-shaped test piece, and the light transmittance in the thickness direction was measured at a wavelength of 600 nm. Then, after immersing the test piece in hot water of 80 ° C. for 12 hours,
Immediately immersed in distilled water at room temperature (20 ° C.), cooled to room temperature, taken out of the distilled water, wiped the surface of water with gauze, and measured the light transmittance in the thickness direction at a wavelength of 600 nm. The presence or absence of whitening is visually observed, and the case where whitening does not occur at all is extremely good (◎), the case where whitening hardly occurs is good (○), and the case where whitening is slight is poor (△), whitening Was evaluated as extremely poor (x).

(13) Hot water bleaching resistance of a laminate: A test piece was cut out from a laminate having a thickness of 2 mm manufactured by co-melt extrusion molding, and the test piece was immersed in warm water of 80 ° C. for 12 hours and then cooled to room temperature ( (20 ° C.), cooled immediately to room temperature, taken out of the distilled water, wiped the surface of water with gauze, and visually observed for whitening. that time,
The case where whitening did not occur at all was extremely good (◎), the case where almost no whitening occurred was good (○), the case where slight whitening was poor (△), and the case where whitening was remarkable was extremely poor (×). evaluated.

Example 1 (1) 150 parts of deionized water and sodium dioctylsulfosuccinate were placed in a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet, a monomer inlet tube, and a reflux condenser. 5
And 0.05 parts of sodium carbonate, and the inside of the vessel was sufficiently replaced with nitrogen gas to substantially eliminate the influence of oxygen, and then the internal temperature was set to 80 ° C. Thereto was added 0.015 part of potassium persulfate, and the mixture was stirred for 5 minutes. Then, a monomer mixture consisting of 14.67 parts of methyl methacrylate, 0.3 part of n-butyl acrylate and 0.03 part of allyl methacrylate was added to 20 parts of the mixture. The polymerization was continued for 30 minutes so that the polymerization conversion rate became 98% or more, and the innermost layer hard polymer (a) was added.
Was manufactured. (2) Next, potassium persulfate 0.0
After charging 30 parts and stirring for 5 minutes, a monomer mixture consisting of 29.4 parts of n-butyl acrylate and 0.6 part of allyl methacrylate was continuously added dropwise over 40 minutes, and after the addition was completed, polymerization was completed. Polymerization was further performed for 30 minutes so that the conversion became 98% or more, to produce a layered granular material having a polymer layer composed of the soft layer polymer (b) on the innermost layer hard polymer (a). (3) Next, 0.05% potassium persulfate was placed in the reactor.
After charging 5 parts and stirring for 5 minutes, a monomer mixture containing 53.9 parts of methyl methacrylate, 1.1 parts of n-butyl acrylate and 0.5 part of n-octyl mercaptan (chain transfer agent) was added for 100 minutes. After completion of the addition, polymerization is further carried out for 60 minutes so that the polymerization conversion rate becomes 98% or more, and the outermost layer hard polymer (c) is formed on the soft layer polymer (b). An aqueous dispersion (latex) containing an acrylic multi-layered granular composite having a polymer layer was obtained. A small amount of this latex was collected, and the average particle size of the acrylic multi-layered granular composite contained therein was determined by the absorbance method as described above.
μm.

(4) The latex of the acrylic-based multi-layered granular composite obtained in the above (3) is frozen at a temperature of -20 ° C. for 1 hour, and a three-fold amount of the resulting frozen product is obtained. It was poured into hot water at 80 ° C. and melted to form an aggregated slurry. Next, the aggregated slurry was dehydrated by a centrifugal separator and dried at 80 ° C. to obtain an aggregated granular material of an acrylic multi-layered granular composite. The average particle size, apparent density, and compression ratio of this aggregated granular material were determined by the methods described above. The average particle size was 165 μm, and the apparent density was 0.48 g.
/ Cm ³ and a compression ratio under pressure of 10%. (5) The aggregated granular material of the acrylic-based multilayer composite obtained in the above (4) is supplied to an extruder, and pellets (diameter 2 mm, length 3 m) at a melt extrusion temperature of 240 ° C.
m) was prepared. (6) The thermal stability of the pellet obtained in the above (5) was evaluated by the method described above, and a test piece was produced using the pellet obtained in the above (5), and the various physical properties were described above. The results were as shown in Table 4 below.

Examples 2 to 5 and Comparative Examples 1 to 3 The innermost hard polymer (a) and the outermost hard polymer (c) were
Except for using the monomer mixture shown in Table 2 or Table 3 below, a latex of an acrylic-based multi-layered granular composite was produced in exactly the same manner as in Example 1, and the acrylic-based multi-layered structure was used therewith. Agglomerated granules of the granular composite were produced. Pellets are produced from the obtained aggregated granules, and the thermal stability of the resulting pellets is evaluated by the method described above, and a test piece is produced using the pellets, and various physical properties thereof are described above. The result was as shown in Table 4 below.

<< Examples 6 to 7 and Comparative Example 4 >> In producing an acrylic multi-layered granular composite, the amount of the emulsifier was reduced and the average particle size of the resulting acrylic multi-layered granular composite was determined as follows. Except for changing as shown in Table 2 or Table 3, a latex of an acrylic multi-layered granular composite was produced in exactly the same manner as in Example 1, and the latex of the acrylic multi-layered granular composite was used by using the latex. Was manufactured. Pellets are produced from the obtained aggregated granules, and the thermal stability of the resulting pellets is evaluated by the method described above,
A test piece was manufactured using the pellets, and various physical properties thereof were examined by the methods described above. The results were as shown in Table 4 below.

<< Examples 8 to 10 and Comparative Examples 5 to 7 >> The layer ratios of the innermost hard polymer (a), the soft layer polymer (b) and the outermost hard polymer (c) are shown in Table 2 below. Or Table 3
Except that it was changed as shown in Example 1.
Producing latex of acrylic multi-layered granular composite,
It is used to produce an aggregated granular material of an acrylic multilayered granular composite, to produce a pellet from the aggregated granular material, and to evaluate the thermal stability of the resulting pellet by the method described above. A test piece is manufactured using
The various physical properties were examined by the methods described above, and the results were as shown in Table 4 below.

[0074]

[Table 2]

[0075]

[Table 3]

[0076]

[Table 4]

[0077] From the results of Tables 2 to 4 above, methyl methacrylate 80 to 98.99 wt%, C _{1 to 8} alkyl acrylates 1-20 wt%, a polyfunctional grafting agent 0.0
1-1 wt% and the polyfunctional crosslinking agent consists of 0-0.5 wt% monomer mixture polymerizes to become the innermost layer hard polymer _(a), C 1~8 alkyl acrylates 70 to 99.5 wt %, 0 to 30% by weight of methyl methacrylate, 0.5 to 5% by weight of a polyfunctional grafting agent and 0 to 5% of a polyfunctional crosslinking agent.
Soft layer polymer (b) obtained by polymerizing a monomer mixture consisting of 5% by weight, and 90 to 99% by weight of methyl methacrylate and 10 to ₁ % by weight of C1-8 alkyl acrylate
Has a glass transition point of 8 obtained by polymerizing a monomer mixture consisting of
An acrylic multi-layered granular composite comprising an outermost hard polymer (c) at 0 ° C. or higher, and an innermost hard polymer (a): a soft layer polymer (b): an outermost hard polymer (c) )
Is 5-30: 20-45: 50-
The acrylic multilayer-structured granular composites (agglomerated granular materials) of Examples 1 to 10 having an MFR in the range of 0.5 to 20 g / 10 minutes are excellent in heat stability and film moldability. Moreover, it can be seen that a molded product (film) having excellent impact resistance, stress whitening resistance and hot water whitening resistance can be produced.

On the other hand, from the results in Tables 2 to 4, the proportion of the structural unit constituting the innermost hard polymer (a) or the outermost hard polymer (c) is out of the range of the present invention. Or the layer ratio of the innermost layer hard polymer (a), the soft layer polymer (b) and the outermost layer hard polymer (c) is out of the range of the present invention, or the average of the acrylic multi-layered granular composite. In the case of Comparative Examples 1 to 7 in which the particle size is out of the range of the present invention, the thermal stability, film moldability, impact resistance, and impact resistance of the acrylic multi-layered granular composite (agglomerated granular material) are obtained. It can be seen that physical properties are inferior in one or more of the stress whitening property and the hot water whitening resistance.

<< Examples 11 to 17 >> The pellets comprising the aggregated granular material of the acrylic multi-layered granular composite obtained in Example 1 were supplied to an extruder (screw diameter: 30 mm) and the cylinder temperature was set to 250 ° C. On the other hand, the thermoplastic polymer pellets described in Table 4 below were supplied to another extruder (screw diameter 50 mm) and melted at the cylinder temperature shown in Table 5 below, and both melts were melted. 350m width
m is supplied to a co-extrusion die for the production of a sheet having a thickness of 50 μm and a coating layer made of an acrylic multi-layered granular composite on both sides of a layer made of a thermoplastic polymer. Produced a laminated plate composed of two kinds and three layers having a thickness of 2 mm. At this time, the laminate moldability was evaluated by the above-described method, and the stress whitening resistance and hot water whitening resistance of the obtained laminate were examined by the above-described method. The results were as shown in Table 5 below. . In addition, the thickness of the coating layer made of the acrylic-based multi-layered granular composite in the laminate was measured using an optical microscope after cutting out a test piece from the laminate and polishing the cut surface.

<< Comparative Examples 8 to 10 >> Pellets made of agglomerated granules made of the acrylic multi-layered granular composites of Comparative Examples 1, 3 and 4 (Comparative Examples 8, 9 and 10) Example 1 except for using
A laminate was manufactured in the same manner as in Example 1, and the measurement and evaluation were performed. The results are shown in Table 5 below.

[0081]

[Table 5]

From the results shown in Table 5 above, it is clear that the acrylic multi-layered granular composite of the present invention is excellent in lamination moldability with a thermoplastic polymer, and that the multi-layered acrylic multi-layered granular composite of the present invention has It can be seen that a laminate having a layer made of a thermoplastic polymer and a layer made of a thermoplastic polymer is also excellent in properties such as stress whitening resistance and hot water whitening resistance.

[0083]

The acrylic multi-layered granular composite of the present invention and the agglomerated granular body comprising the same have excellent moldability, heat stability, beautiful appearance, excellent transparency and weather resistance inherent to acrylic resins. It has excellent properties such as impact resistance, stress whitening resistance and hot water whitening resistance even without blending with other thermoplastic polymers or elastic polymers. Without causing a decrease in transparency or weather resistance caused by blending with the polymer,
By itself, a molded product or a laminate having excellent appearance, transparency, weather resistance, stress whitening resistance, hot water whitening resistance, thermal stability, etc. can be produced with good moldability and high productivity.
In particular, the acrylic-based multi-layered granular composite of the present invention and the aggregated granular body comprising the same have been conventionally considered unsuitable for acrylic resins, even in thin molded products such as films and sheets, and have good moldability. The physical properties are excellent, and a thin molded article such as a film obtained by using the acrylic-based multi-layered granular composite of the present invention and the aggregated granular material comprising the same has excellent appearance, transparency, impact resistance, etc., and is folded. No whitening occurs even when stress such as stretching or stretching is applied, and no whitening occurs when exposed to warm water.

Further, the acrylic-based multi-layered granular composite of the present invention and the agglomerated granular material comprising the same have excellent adhesion to other thermoplastic polymers, and can be co-melt extruded with other thermoplastic polymers. By laminating by the method described above, a laminate having no delamination and excellent in stress whitening resistance, hot water whitening resistance, mechanical properties, and the like can be produced with good lamination moldability and high productivity.

The average particle size obtained by agglomeration of the acrylic multi-layered granular composite of the present invention is 100 to 50.
The agglomerated granules of the present invention having a particle size of 0 μm, an apparent density of 0.3 g / cm ³ or more, and a compression ratio of less than 30% are hardly scattered, are excellent in handleability and moldability, and are excellent in extrusion molding and injection molding. Can be formed smoothly, the dispersibility of other additives in the aggregated granules is good, no blocking or adhesion to equipment occurs during handling or storage, and the appearance of buttocks (fish eyes) A molded article having no mechanical properties and excellent mechanical properties can be produced.

The acrylic multi-layered granular composite of the present invention having the above-mentioned excellent properties can be obtained by the above-mentioned polymerization step (1).
It can be produced smoothly by the method of the present invention comprising (3). In addition, the aggregated granular material comprising the acrylic multilayer structure granular composite of the present invention having the above-described excellent properties was obtained by freezing an aqueous dispersion containing the acrylic multilayer structure granular composite of the present invention, and then melting it. Thereafter, it can be obtained smoothly by the method of the present invention comprising dehydration and drying.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C08F 20/18 C08F 20/18 C08L 33/06 C08L 33/06

Claims (10)

[Claims] 1. An acrylic multi-layered granular composite, wherein: (I) the acrylic multi-layered granular composite comprises: (i) 80 to 98.9% by weight of methyl methacrylate; 1 to 20% by weight of at least one alkyl acrylate, 0.01 to 1% by weight of a polyfunctional grafting agent, and 0 to 0 of a polyfunctional crosslinking agent.
An innermost layer hard polymer (a) obtained by polymerizing a monomer mixture comprising 0.5% by weight; (ii) an alkyl group having 1 carbon atom in the presence of the innermost layer hard polymer (a). At least one of alkyl acrylates having a molecular weight of 0 to 8; 70 to 99.5% by weight of methyl methacrylate;
A soft layer polymer (b) obtained by polymerizing a monomer mixture consisting of 5% by weight and a polyfunctional crosslinking agent of 0 to 5% by weight; and (iii) the innermost layer hard polymer (a) and a soft layer polymer. In the presence of polymer particles consisting of the layer polymer (b), at least one of an alkyl acrylate having 90 to 99% by weight of methyl methacrylate and an alkyl group having 1 to 8 carbon atoms is used.
An outermost layer hard polymer (c) having a glass transition point of 80 ° C. or higher obtained by polymerizing a monomer mixture comprising 0 to 1% by weight;
(II) 5 to 30% by weight of the innermost layer hard polymer (a), based on the weight of the acrylic multi-layered granular composite,
20 to 45% by weight of the soft layer polymer (b) and 50 to 75% by weight of the outermost hard polymer (c); (III) the average particle size is 0.01 to 0.3 μm; And (IV) a melt flow rate under a load of 3.8 kg at 230 ° C. of 0.5 to 20 g / 10 minutes; 2. The innermost layer hard polymer (a), the softer layer polymer (b) and the outermost layer hard polymer (c) are based on the total weight of the monomer mixture used to form each polymer. 2. The acrylic multi-layered granular composite according to claim 1, wherein the mixture is formed by performing polymerization while supplying the monomer mixture to the polymerization system at a supply rate of 0.05 to 3% by weight / minute. 3. An agglomerated granule obtained by aggregating the acrylic multi-layered granular composite according to claim 1 or 2, having an average particle size of 100 to 500 μm and an apparent density of 0.3 g / g.
An agglomerated granule characterized by having a compression ratio of not less than 30 cm ³ and a compression ratio of less than 30%. 4. A molded article comprising the acrylic-based multilayered granular composite according to claim 1 or 2 or the aggregated granular material according to claim 3. 5. The molded article according to claim 4, which is a film or a sheet. 6. A layer formed from the acrylic-based multi-layered granular composite according to claim 1 or 2 or at least one layer formed from the agglomerated granular material according to claim 3, and at least one layer formed of another thermoplastic polymer. A laminate having one layer. 7. A layer made of another thermoplastic polymer may be made of a polycarbonate polymer, a vinyl chloride polymer, a vinylidene fluoride polymer, a methacrylic resin, an ABS resin, and an AE.
The laminate according to claim 6, comprising at least one selected from S resin and AS resin. 8. (1) Methyl methacrylate 80-9
8.99% by weight, at least one alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, 1 to 20% by weight,
A hard polymer is produced by polymerizing a monomer mixture comprising 0.01 to 1% by weight of a polyfunctional grafting agent and 0 to 0.5% by weight of a polyfunctional crosslinking agent in an aqueous medium, (2) In an aqueous medium in the presence of a hard polymer obtained in the polymerization step (1) of at least one of alkyl acrylates having 1 to 8 carbon atoms in an amount of 70 to 99.5% by weight, methyl methacrylate 0 to 30 % By weight, polyfunctional grafting agent 0.
Polymerizing a monomer mixture consisting of 5 to 5% by weight and 0 to 5% by weight of a polyfunctional crosslinking agent to produce polymer particles comprising a soft polymer laminated on the hard polymer, and (3) ) In the presence of the polymer particles obtained in the polymerization step (2),
In an aqueous medium, a monomer mixture consisting of 90 to 99% by weight of methyl methacrylate and 10 to 1% by weight of at least one alkyl acrylate having 1 to 8 carbon atoms in the alkyl group is polymerized to form a mixture on the soft polymer. Glass transition point is 8
Forming a layer of a hard polymer having a temperature of 0 ° C. or higher, and based on the total weight of the monomers used in the production of the acrylic multi-layered granular composite, the monomer used in the polymerization step (1) The proportion of the mixture is from 5 to 30% by weight, and the proportion of the monomer mixture used in the polymerization step (2) is from 20 to 45% by weight.
The method for producing an acrylic-based multi-layered granular composite according to claim 1, wherein the ratio of the monomer mixture used in the polymerization step (3) is 50 to 75% by weight. 9. The polymerization step (1) and the polymerization step (2)
And in the polymerization step (3), based on the total weight of the monomer mixture used in each step,
9. The production method according to claim 8, wherein the polymerization is carried out in each step by supplying to each polymerization system at a supply rate of up to 3% by weight / minute. 10. The coagulation according to claim 3, wherein the aqueous dispersion containing the acrylic multi-layered granular composite according to claim 1 or 2 is frozen, then melted, and then dehydrated and dried. A method for producing a granular material.