JP2000204128A - Shockproof acrylic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pelletized shockproof acrylic polymer excellent in handling property and having a large content of rubbery elastic bodies. SOLUTION: Pelletized shockproof acrylic polymer containing a polymer having an acrylic multilayered structure in high concentration. The acrylic multilayered structure has at least one rubbery elastic layer as an inner layer and a hard polymer layer mainly composed of methyl methacrylate as the outermost layer. The acrylic polymer is characterized in that the content of an acetone-insoluble part containing the rubbery elastic layer is 70-97 wt.% per pellet unit weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellet-shaped impact-resistant acrylic polymer having excellent handling properties and containing a large amount of rubber-like elastic material.

[0002]

2. Description of the Related Art Methacrylic resins have excellent weather resistance, gloss and transparency, but have the disadvantage of low impact resistance. Therefore, introduction of an acrylic elastomer is an effective means for imparting impact resistance while maintaining weather resistance, and an acrylic two-layer structure composed of a rubber-like polymer and a hard-like polymer has been used so far. 3 of polymer or semi-rubber-like polymer, rubbery polymer and hard polymer
There is known a method of blending an acrylic three-layer polymer having a three-layer structure with a methacrylic resin (US Pat. No. 3,80).
8,180, 3,843,753, 4,730,023 and JP-A-62-230841.
No.).

[0003] Such an acrylic-based multilayer structure polymer is:
It is a powdery product obtained by coagulating, dehydrating, and drying an latex of an acrylic multilayer structure polymer produced by an emulsion polymerization method. On the other hand, a production method in which a mixture of a water-containing polymer containing a rubber component is supplied to a compression dewatering extruder, dewatered, kneaded, and melted in a barrel, and then taken out as a flake-like powder from the open end of the barrel with the open end ( JP-A-4-13920
No. 2) is also known.

The inventors of the present invention have studied the powder structure of a coagulated powder having excellent drying efficiency for a relatively hard acrylic multi-layer polymer, and have found that the coagulated powder has a specific void structure and It has been found that a powder having a relatively small proportion of fine powder is suitable for a drying method such as a compression dewatering extruder and has an excellent drying efficiency. That is, the emulsified latex of an acrylic multi-layer structure polymer is coagulated, and the ratio of fine powder having a particle size of 212 μm or less is 40% by weight or less, and the obtained coagulated powder is measured by a mercury intrusion method after drying the coagulated powder. A powder having a pore volume of 5 μm or less and a void volume of 0.7 cc or less per dry unit weight is suitable for a drying method such as a compression dehydration extruder. (Japanese Unexamined Patent Application Publication No. 8-24)
No. 5854: U.S. Pat. No. 5,521,252).

[0005] The impact-resistant acrylic resin comprising a composition of an acrylic multilayer structure polymer and a methacrylic resin is obtained by mixing the above-mentioned powdery or granular polymer with methacrylic resin obtained by a suspension polymerization method. Mixing with polymer polymer beads or methacrylic polymer pellets obtained by bulk polymerization method, melting and plasticizing using an extruder, continuously extruding from the tip die, cutting the extruded molten strand Thus, it is obtained as a pellet. However, in this method, since a powdery acrylic multi-layer structure polymer is used, there is a problem that dust is scattered at the time of blending with a methacrylic resin and workability is poor. Further, the above-mentioned granular acrylic multi-layer structure polymer is improved in dust scattering and the like as compared with a powdery one, but is not sufficient. Therefore, it is desirable that the acrylic multi-layer structure polymer has a pellet shape excellent in handling properties.

On the other hand, a pellet made of a composition of an acrylic multi-layer structure polymer and a methacrylic resin is used as a master pellet, and a small amount of the master pellet is added to the methacrylic resin to obtain an impact-resistant acrylic resin. There is a demand for a technology that can be manufactured. In order to satisfy this requirement, it is necessary to provide an acrylic multilayer polymer or a master pellet having a large content of a rubber-like elastic material.

However, in the conventional method for producing pellets by mixing a powdery or granular acrylic polymer having a multilayer structure and a methacrylic resin with an ordinary extruder, the content of the rubbery elastomer is 40 to 50. % Or more, there is a quality problem such that the discharge of the strand is likely to be unstable, and coloring and physical properties are deteriorated due to thermal deterioration. That is, the pellets (or master pellets) containing the acrylic multilayer polymer in the examples of the prior art
As a specific example, the content of a rubber-like elastic material is 30% (Japanese Patent Laid-Open No. 62-230841).
Or 17.5% (JP-A-5-17654), which has a relatively low rubber content and a rubber-like elastic material content of 5%.
There is no thing more than 0%.

As a technique for producing a pellet containing a rubber component, an ABS resin, which is one of impact-resistant resins, is prepared by, for example, graft graft polymerization obtained by emulsion-grafting a vinyl monomer onto a diene rubber-like polymer. The polymer slurry obtained by coagulating the coalesced latex is directly supplied to the compression dewatering extruder, and dewatered, kneaded, melted and plasticized in the barrel,
There is known a method of continuously extruding a strand from a die at the tip of the extruder and cutting the same to produce a pellet-shaped ABS resin. Further, a method of supplying a mixture of the polymer slurry and a vinyl-based polymer slurry obtained by a suspension or bulk polymerization method to a compression dewatering extruder and producing a pellet-shaped ABS resin in the same manner as described above is also available. It is known (JP-B-59-37021). However, ABS resins have remarkably different melting properties from methacrylic resins.
Although suitable for soft polymers that are relatively easy to melt, such as S-based resins, they have been unsuitable for hard polymers, such as acrylic polymers.

That is, in order to impart impact resistance without sacrificing the inherent luster and transparency of the methacrylic resin, the acrylic multi-layer structure polymer must be made of an alkyl acrylate or the like in the acrylic multi-layer structure polymer. It is necessary to reduce the content of the rubber component and relatively increase the content of the hard component such as alkyl methacrylate. This is because, when the ratio of the rubber-like component is relatively large, the change in the refractive index with respect to the temperature is large and the optical characteristics are impaired. Therefore, such an acrylic multi-layer structure polymer is inevitably hard, and the coagulation of the polymer particles in the emulsified latex hardly occurs during coagulation, and the water content of the recovered wet polymer is reduced. Tend to be relatively high.

Turning now to practical applications of the impact-resistant acrylic resin, the impact-resistant acrylic resin has a good molded appearance and impact resistance, so that the front panel of a signboard or a vending machine is used. It is widely used for visors for automobiles and the like, and required performances such as weather resistance are becoming more and more advanced. Therefore, generally, when a composition is produced by mixing an acrylic multilayer polymer and a methacrylic resin, an organic stabilizer is further added to adopt a method of further improving the appearance and weather resistance. In such a method, when a large number of types of stabilizers are used, a great deal of labor is required, the production efficiency is reduced and the product cost is increased, and the environment when the stabilizer is added is contaminated. In some cases, there is a problem in that the obtained acrylic resin composition is contaminated and its performance is reduced. Therefore, an impact-resistant acrylic polymer to which an organic stabilizer is added in advance is desired. That is, it is preferable that an organic stabilizer is added to the master pellet containing a large amount of the rubber-like elastic material in some cases.

[0011]

That is, there has not been known a technique capable of providing a master pellet containing a large amount of rubber containing an acrylic multi-layer structure polymer. An object of the present invention is to provide a master pellet having a high content of a rubber-like elastic body.

[0012]

The present inventor has developed a technique for drying an acrylic multi-layer polymer powder using the above-mentioned compression dewatering extruder (Japanese Patent Laid-Open No. 8-245854: US Pat. No. 5,521). 252) is further improved, and it is found that a master pellet having a high content of a rubber-like elastic body can be produced by melting and plasticizing the acrylic multilayer structure polymer into a pellet form by a specific method. The present invention has been completed.

That is, the present invention provides an acrylic multilayer polymer having at least one rubber-like elastic layer (α) as an inner layer and a hard polymer layer (β) containing methyl methacrylate as a main component as an outermost layer. Wherein the content of the acetone-insoluble portion including the rubber-like elastic layer (α) is from 70 to 97% by weight per unit weight of the pellet in the pellet-shaped impact-resistant acrylic polymer. It is an impact-resistant acrylic polymer.

In the present invention, the rubber-like elastic layer (α) may be a monofunctional compound having 40 to 90% by weight of an alkyl acrylate having an alkyl group having 8 or less carbon atoms and at least one vinyl group copolymerizable therewith. 0.1 part by weight based on 100 parts by weight of a monomer mixture consisting of 10 to 60% by weight of the monomer.
A polymer prepared from 0.1 to 10 parts by weight of a graft crosslinking agent and 0.1 to 10 parts by weight of a polyfunctional crosslinking agent having at least two vinyl groups, wherein the hard polymer layer (β)
It is composed of a polymer produced from 60 to 100% by weight of an alkyl methacrylate having an alkyl group having 4 or less carbon atoms and 0 to 40% by weight of an unsaturated monomer copolymerizable therewith. It is an impact acrylic polymer.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The impact-resistant acrylic polymer of the present invention is in the form of pellets, and contains a large number of acrylic multilayered polymers (hereinafter, appropriately referred to as "multilayer polymer").
This multilayer polymer has at least one rubbery elastic layer (α) as an inner layer, and a hard polymer layer (β) as an outermost layer.
have.

The content of the acetone-insoluble portion of the multilayer polymer in the present invention is 70 to 97% by weight per unit weight of the pellet. The content of the rubber-like elastic material contained in the multilayer polymer is preferably from 50 to 90% by weight, and preferably from 55 to 8% by weight.
0% by weight, more preferably 60 to 75% by weight.
Is particularly preferred. Here, the content of the rubber-like elastic body refers to the total weight of the rubber-like elastic layer (α) and all the polymer layers inside the rubber-like elastic layer (α) with respect to the total weight of the multilayer polymer. And this value is calculated from the weight ratio of the monomer mixture in each polymer layer.

If the content of the rubber-like elastic material is too small, the effect of improving the impact resistance is difficult to be exhibited, which is not preferable. Also,
When the content of the rubber-like elastic material is too large, the outermost layer portion is reduced, so that the compatibility between the multilayer polymer and the matrix resin may be deteriorated.

The multilayer polymer useful in the present invention has a glass transition temperature (hereinafter abbreviated as Tg) when polymerized alone.
Having at least one rubber-like elastic layer (α) composed of a polymer having a temperature of 25 ° C. or less as an inner layer, and having a Tg of 50 ° C. or more when polymerized alone. Having a hard polymer layer (β) as the outermost layer. Therefore, the inner layer only needs to have at least one rubber-like elastic layer (α), and a multilayer polymer having a structure in which one or more intermediate layers or the innermost layer is further provided can be used. As a specific structure, for example, a two-layer polymer in which the inner layer is a rubber-like elastic layer (α), the outer layer is a hard polymer layer (β), or the innermost layer is a hard polymer layer, and the intermediate layer is a rubber-like elastic layer Body layer (α), a three-layer polymer in which the outermost layer is a hard polymer layer (β), or a rubbery elastic layer (α) in the innermost layer, a hard polymer layer in the second layer, and a third layer And a four-layer polymer in which the outermost layer is a hard polymer layer (β). These multilayer polymers have a salami structure in which a plurality of hard polymers are dispersed in a rubber-like elastic layer (α) and a salami structure in which a plurality of rubber-like elastic materials are dispersed in an inner hard polymer layer. Can also be taken.

The rubbery elastic layer (α) constituting the inner layer or the intermediate layer comprises 40 to 90% by weight of an alkyl acrylate having an alkyl group having 8 or less carbon atoms and at least one vinyl group copolymerizable therewith. Monofunctional monomer 1 having
0.1 to 10 parts by weight of a graft crosslinking agent and 0.1 to 1 of a polyfunctional crosslinking agent having at least two vinyl groups per 100 parts by weight of a monomer mixture consisting of 0 to 60% by weight.
Copolymers prepared from 0 parts by weight are preferred. The ratio between the alkyl acrylate and the monofunctional monomer is determined by the refractive index when transparency of the resin is required. However, when the amount of the alkyl acrylate is small, the impact resistance tends to decrease. Tg of the polymer constituting the rubbery elastic layer (α)
The lower the temperature, the higher the impact resistance of the obtained resin composition at low temperature can be improved. Therefore, the Tg when polymerized alone is preferably 25 ° C. or lower, more preferably 10 ° C. or lower.

Examples of the alkyl acrylate having an alkyl group having 8 or less carbon atoms include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate and 2-ethylhexyl acrylate, and particularly preferred is n-butyl acrylate. .
These can be used alone or in combination.
Examples of the copolymerizable monofunctional monomer include aromatic unsaturated monomers such as styrene, vinyl toluene and α-methylstyrene, and methacrylic monomers such as phenyl methacrylate and naphthyl methacrylate. In particular, styrene is preferable as a monomer for adjusting the refractive index.

[0021] A graft crossing agent is a compound having a plurality of functional groups, wherein the reactivity of at least one functional group is different from the reactivity of other functional groups. For example, acrylic acid, methacrylic acid, Allyl esters of maleic acid or fumaric acid and the like can be mentioned. Of these, allyl acrylate and allyl methacrylate are particularly preferred. The polyfunctional crosslinking agent has a plurality of functional groups having the same reactivity in the molecule, and examples thereof include 1,3-butylene methacrylate and 1,4-butanediol diacrylate.

On the other hand, the hard polymer layer (β) constituting the outermost layer is preferably composed of a polymer having a Tg of 50 ° C. or higher when polymerized alone. Those comprising 60 to 100% by weight of an alkyl methacrylate and 0 to 40% by weight of another unsaturated monomer copolymerizable therewith are preferred. Examples of the alkyl methacrylate having an alkyl group having 4 or less carbon atoms include methyl methacrylate, ethyl methacrylate and n-butyl methacrylate, with methyl methacrylate being particularly preferred. Examples of unsaturated monomers copolymerizable therewith include the alkyl acrylates exemplified as monomers for rubber-like elastic bodies, copolymerizable monofunctional monomers, and 1,3-butadiene; 2,3-butadiene, vinyl toluene, cyclohexyl methacrylate,
Benzyl methacrylate, acrylonitrile, methacrylonitrile and the like can be mentioned, and these can be used alone or in combination.

The hard polymer layer (β) has a function of improving the compatibility between the rubber-like elastic layer (α) and the matrix resin by graft bonding with the inner layer portion. Therefore, the ratio of the hard polymer layer (β) in the multilayer polymer is preferably from 10 to 50% by weight. If the ratio of the hard polymer layer (β) is too small, the compatibility between the multilayer polymer and the matrix resin becomes poor, and the coating of the rubber-like elastic body becomes incomplete,
The adhesiveness between the multilayer polymers may increase, and the handleability may deteriorate. On the other hand, if the ratio of the hard polymer layer (β) is too large, the content of the rubber-like elastic body is reduced, and the effect of improving the impact resistance is hardly exhibited.

Further preferred examples of the multilayer polymer include:
Grafted to 100 parts by weight of a monomer mixture comprising 5 to 70% by weight of at least one monomer selected from an alkyl acrylate having an alkyl group having 8 or less carbon atoms and styrene and 30 to 95% by weight of methyl methacrylate. 0.1 to 5 parts by weight of cross-linking agent and 1 to 5 of polyfunctional crosslinking agent
Innermost layer polymer (γ1) obtained by polymerizing a monomer mixture consisting of parts by weight, 70 to 90% by weight of an alkyl acrylate having an alkyl group having 8 or less carbon atoms, A rubber-like polymer obtained by polymerizing a monomer mixture comprising 1 to 3 parts by weight of a graft crosslinking agent and 0.1 to 1 part by weight of a polyfunctional crosslinking agent with respect to 100 parts by weight of a monomer mixture comprising 30% by weight. Elastic layer (α1) and hard polymer layer obtained by polymerizing a monomer mixture consisting of 85 to 97% by weight of methyl methacrylate and 3 to 15% by weight of alkyl acrylate having 4 or less carbon atoms (Β1) having a three-layer structure.

Here, the ratio of each layer in the multilayer polymer is 20 to 35% by weight for the innermost layer polymer (γ1), 30 to 70% by weight for the rubbery elastic layer (α1), and the hard polymer layer. (Β1) is preferably from 10 to 50% by weight.

An alkyl acrylate having an alkyl group having 8 or less carbon atoms and an alkyl acrylate having an alkyl group having 4 or less carbon atoms constituting these multilayer polymers.
For example, those described above may be mentioned. Examples of the graft crosslinking agent and the polyfunctional crosslinking agent include those described above.

The multilayer polymer in the present invention is produced by emulsion polymerization, and the emulsion polymerization is carried out with an arbitrary monomer composition as long as the above-mentioned polymer constitutional unit can be formed.

The polymerization method is not particularly limited. Examples of the radical polymerization initiator include benzoyl peroxide, cumene hydroperoxide, peroxides such as hydrogen peroxide, azo compounds such as azobisisobutyronitrile, and the like.
Redox initiators comprising persulfate compounds such as ammonium persulfate and potassium persulfate, perchloric acid compounds, perboric acid compounds, and combinations of peroxides and reducing sulfoxy compounds.

The monomers and the polymerization initiator are added by a known method such as a batch addition method, a division addition method, a continuous addition method, a monomer addition method, an emulsion addition method, and the like. Further, the reaction system may be replaced with nitrogen in order to smoothly proceed the reaction, the reaction system may be heated after the completion of the reaction in order to remove residual monomers, or a special catalyst may be added.

The appropriate polymerization temperature for forming the polymer of each layer is in the range of 30 to 120 ° C., preferably 50 to 100 ° C. for each layer. The weight ratio of the monomer / water is not particularly limited, but is preferably about 1/1 to 1/5, more preferably 1 / 1.5 to 1/3. In addition, additives usually added at the time of polymerization, such as a chain transfer agent and an ultraviolet absorber, can be used.

The emulsifier used in the present invention is not particularly limited, but is preferably a phosphate salt or a mixture thereof. For example, mono-n-butylphenylpentaoxyethylene phosphoric acid, di-n-butylphenylpentaoxyethylene phosphoric acid, mono-n-pentylphenylhexaoxyethylene phosphoric acid, di-n-pentylphenylhexaoxyethylene phosphoric acid, -N-heptylphenylpentaoxyethylene phosphate, di-n-heptylphenylpentaoxyethylene phosphate, mono-n-pentyloxyheptaoxyethylene phosphate, di-n-pentyloxyheptaoxyethylene phosphate, mono-n −
Hexyloxypentaoxyethylene phosphoric acid, di-n-
Hexyloxypentaoxyethylene phosphate alkali metal salts or alkaline earth metal salts are mentioned. The alkali metal is preferably sodium or potassium, and the alkaline earth metal is preferably calcium or barium. These phosphoric acid ester salts can be used alone or as a mixture of a monoester and a diester.

The amount of the phosphoric acid ester salt used is not particularly limited since it is closely related to the type of the monomer to be polymerized, the polymerization conditions, and the like.
0.1 to 10 parts by weight, preferably 0.5 part by weight, and 0.5 part by weight
A range of from 5 to 5 parts by weight is more preferable.

The coagulation method for recovering the multilayer polymer from the emulsified latex in the present invention is not particularly limited. However, in order to increase the drying efficiency in the compression dehydration extrusion described below, the coagulated powder has a small water content and A method in which the amount of fine powder is reduced is preferable.

Specifically, at a temperature of 90 ° C. or more, the concentration is 1.8 to
A method is preferred in which the latex is poured into a 5% aqueous calcium acetate solution (coagulant solution) at a linear velocity of 0.5 m / sec or less to coagulate.

The temperature of the coagulating liquid for obtaining the desired coagulated powder of the multilayer polymer having a small water content and a small proportion of fine powder depends on the kind and amount of the monomer used as the raw material or the coagulation such as shearing force by stirring. Although it is not particularly limited because it is affected by the conditions, a range of 90 ° C to 100 ° C is preferable. If the temperature of the coagulating liquid is too low, the water content of the coagulated powder may be high and the amount of fine powder may be large.

The type of the coagulant is not particularly limited, but a calcium compound having a relatively large coagulation force is preferable in order to reduce the water content, and it is more preferable to use an aqueous solution of calcium acetate. The concentration of the aqueous solution of calcium acetate is preferably 0.1 to 20% by weight, more preferably 1.8 to 5%.
% By weight. If the concentration of the aqueous solution of calcium acetate is too low, the multilayer polymer may not be able to be recovered stably.If the concentration of the aqueous solution of calcium acetate is too high, the aqueous calcium acetate solution may be saturated and calcium acetate may be precipitated, which is preferable. Absent. As the coagulant, other acids, bases and the like can be used in combination, if necessary. However, when used in combination with an inorganic salt such as a sulfate or a carbonate, an insoluble calcium salt is not preferable.

The speed at which the latex is poured into the coagulant solution is also not particularly limited because it is affected by other coagulation conditions, but a method in which the linear velocity is set to 0.5 m / sec or less and the coagulant is poured into the coagulant solution as slowly as possible. Is preferred. If the linear velocity is too high, the water content of the coagulated powder may be relatively large, which is not preferable.

The coagulated powder (wet polymer) obtained by coagulating the emulsified latex is sufficiently washed with water at a weight of about 5 to 100 times the weight of the polymer. If the amount of water used for washing is too small, the amount of the remaining coagulant increases, which is not preferable because the appearance and physical properties of the pellets may be impaired. After washing with water, the coagulated powder is dehydrated by a centrifugal dehydrator or the like, and the water-containing polymer (X)
As supplied to a press dewatering extruder.

In the present invention, a water-containing polymer (X) obtained by coagulating, washing and dehydrating an emulsion latex of a multilayer polymer.
Is dried using a compression dewatering extruder. At this time, in some cases, an organic stabilizer (Y) such as a phosphorus compound, a hindered phenol compound and a hindered amine compound can be added simultaneously.

Generally, in the drying step, the lower the water content of the coagulated powder, the higher the drying speed and the more efficient. The water in question is present in microvoids formed in the multilayer polymer and having a size of several μm or less. For this reason, when the void volume with a pore diameter of 5 μm or less measured by a mercury intrusion method after drying the coagulated powder is 0.7 ml or less per 1 g of dry unit weight, the moisture content is reduced and the drying efficiency is excellent. The smaller the void volume, the better. When the void volume is large, the moisture content in the coagulated powder becomes relatively large, so that the drying speed becomes slow.

In order to efficiently dry the coagulated powder using a compression dehydration extruder, it is effective that the average particle size of the coagulated powder is large and the amount of fine powder is small. Specifically, the coagulated powder has the above-mentioned void structure, and the particle size of the coagulated powder is 212 μm.
It is preferable that the proportion of the following fine powder is 40% by weight or less. The smaller the ratio of the fine powder, the better. In the case where the proportion of the fine powder in the coagulated powder is large, when the supply amount of the coagulated powder is increased, the dewatered water in the pressing section becomes remarkable, and the surging phenomenon easily occurs. Therefore, the supply of the coagulated powder to the compression dewatering extruder is limited, and the limit throughput is reduced. In addition, the limit processing amount means that the supply amount of the hydrated polymer (X) is gradually increased while the screw rotation speed during the compression dehydration extrusion is kept constant, and is discharged from the dehydration slit (4 in FIG. 1). This is the amount of polymer treated (dry base) when water runs out.

The pressing dewatering extruder used in the present invention comprises a raw material charging section, a dewatering section having at least one dewatering slit, a pressing section for removing a liquid material from the hydrated polymer (X), and a vaporized material. It is composed of a deaeration section for discharging. Most of the liquid is dewatered in the dewatering section, and the polymer is heated and melted, extruded from the die at the tip of the extruder, and the extruded strand is immediately cut by a hot cutter or cooled in a cooling bath. After the cutter
And pelletize.

The compression dewatering extruder is basically a kind of screw extruder having a screw, a cylinder, a die, and a screw drive as main components. On the upstream side of the machine, a dewatering slit is provided for discharging the liquid separated from the water-containing polymer in the squeezing section, and on the downstream side, the polymer in which most of the liquid has been dewatered is cooled from room temperature to 400 ° C. It is to have a heating part (degassing part) that can raise the temperature to the temperature range.

The press dewatering extruder is not particularly limited as long as it has the above structure.
The use of a twin-screw dewatering extruder such as TEM-35B is preferred.

As shown in FIG. 1, the twin-screw dewatering extruder has 10 barrel blocks No. 1 to
No. 10, two screws having the same shape are inserted into the barrel with their axes parallel to each other while meshing with each other.

As shown in FIG. 1, the barrel has a barrel block no. 1, No. 3, No. 4, no. 6, N
o. 8, no. 9 and No. 9 Reference numeral 10 denotes a barrel block having the same structure as that used in a normal twin-screw extruder and having no particular structure. No. 2, No. 5 and No. 5 On the side surface of each barrel block 7, there are formed dewatering slits 4, 5, and 6 having slit intervals for allowing only liquid to pass. And barrel block No. 1
A hopper 3 is attached to the raw material inlet 2 on the upper surface of
Above the hopper, a raw material input device (not shown) is provided. A die 9 is attached to the tip of the biaxial pressing dewatering extruder.

The screw to be inserted into the barrel having the above-mentioned structure is constituted by appropriately combining screw blocks and kneading disks having various screw structures and lengths so as to adopt various structures.

In this embodiment, various screw blocks and kneading disks are combined, and two screws having the same structure and a total length of 1244 mm are used.

FIG. 2 shows the screw used in the present invention. The screw S block length / lead length (number) or kneading disk N block length / sheet (number) has the configuration shown in FIG. In the drawing, S indicates a screw block in which the twisting direction is clockwise, L indicates a reverse screw block in which the twisting direction is counterclockwise, and N indicates a kneading disk block in which the twisting direction is clockwise.

A pair of screws 10 having such a configuration are inserted through the barrel 1 while being engaged with each other, and the base ends thereof are connected to a drive source having a speed change function.

Therefore, the twin-screw dewatering extruder of the present embodiment obtained in this manner has a barrel block no. 1 is the raw material input section, barrel block No. 2 is the first dehydrator, N
o. No. 5 is a second dewatering unit, and No. 5 7 constitutes a third dehydrating unit. Barrel block No. 4 to No. 4. No. 5 front part, No. 5 No. 6 rear and No. 6 The front part of 7 constitutes a pressing part composed of a kneading disk and a reverse screw block.

The hydrous polymer (X) obtained by the centrifugal dehydration after coagulation is supplied to such a biaxial compression dehydration extruder from the raw material supply port 2, mixed, dehydrated, dried, melted, and then exited from the die. Then, the mixture is extruded as a molten strand, cooled in a cooling bath, and then cut with a cutter or the like to obtain a pellet-shaped polymer. In some cases, the hydrated polymer (X) is supplied together with the organic stabilizer (Y) from the raw material supply port 2 to obtain a pellet-shaped polymer in the same manner as described above.

The organic stabilizer (Y) used in the present invention includes a phosphorus compound, a hindered phenol compound and a hindered amine compound, and these can be used alone or in combination of two or more. . By adding these organic stabilizers (Y), the transparency of a phosphorus-based compound in a molded plate or the like is improved, the hindered phenol-based compound is improved in thermal decomposition resistance during molding, etc., and the hindered amine-based compound is a molded plate or the like. There is an improvement in weather resistance. However, when a phosphorus-based compound is used, the thermal decomposition resistance during molding or the like tends to be slightly lowered, and when a compound which is easily hydrolyzed is used, the appearance of a molded plate or the like may be slightly deteriorated.

As the organic stabilizer (Y), known compounds can be used. For example, as a phosphorus compound, Adekastab 2112 manufactured by Asahi Denka Kogyo KK, and as a hindered phenol compound, Asahi Kabushiki Kaisha Decastab AO-50, Adecastab AO-60, products of Denka Kogyo Co., Ltd.
As a hindered amine compound, Asahi Denka Kogyo Co., Ltd.
ADK STAB LA-57, ADK STAB LA
-77 and the like.

When used alone, the organic stabilizer (Y) is used in an amount of 0.1 part by weight for the phosphorus compound based on 100 parts by weight of the polymer (based on a dry basis obtained by removing water from the water-containing polymer).
It is preferably 0.01 to 5 parts by weight, 0.01 to 3 parts by weight for a hindered phenol compound, and 0.01 to 3 parts by weight for a hindered amine compound. In any case, if the added amount of the organic stabilizer (Y) is too small, the effect may not be exhibited. On the other hand, if the added amount is too large, bleeding may occur on a molded plate or the like, which is not preferable. When two or more kinds are used, the amount of addition is preferably 0.03 to 5 parts by weight based on 100 parts by weight of the polymer.

The heating temperature in the press dewatering extruder for pelletizing is 200 ° C. to 300 ° C. as the maximum resin temperature.
It is preferable to adjust the temperature in the range of ° C. If the resin temperature is too high, the resin and, in some cases, the organic stabilizer will deteriorate,
When the resin temperature is too low, it is difficult to completely melt the resin. In addition, it is preferable that the deaeration pressure in the deaeration section be lower than normal pressure.

On the other hand, the amount of water discharged in the first dewatering section of the compression dewatering extruder during pelletization is preferably 55% or more, more preferably 60% or more, with respect to the amount of water contained in the water-containing polymer. . If the amount of drainage in the first dewatering section is small, a lot of water will be brought into the deaeration section at the tip,
The obtained pellets are not preferable because they contain water and foam.
For this reason, the screw configuration of the first pressing section on the raw material supply side shown in FIG. 2 enhances the pressing effect by increasing the number of L screws and the number of kneading disc blocks as compared with the conventional one, and increases the water content. It facilitates the discharge of water from the coalescence (X).

In the impact-resistant acrylic polymer pellets obtained in the present invention, the amount of alkaline earth metal derived from a coagulant (eg, calcium acetate or the like) used for coagulating the emulsion latex of the multilayer polymer is reduced. It is preferably at most 700 ppm. If the amount of the residual coagulant is too large, the appearance and physical properties of a molded plate or the like may be impaired. In the compression dewatering, the remaining coagulant dissolved in water is discharged together with water in the first dewatering section, so that the residual amount tends to be relatively small, but as described above, the residual coagulant amount is larger than the slurry washing water amount. Affected.

The pelletized impact-resistant acrylic polymer thus obtained is added with a methacrylic resin and other stabilizers, plasticizers, dyes and the like, if necessary, mixed with a Henschel mixer or the like, and then directly. , Injection molding and extrusion molding. In some cases, after mixing with a Henschel mixer or the like, the mixture can be pelletized again by a known method such as melt-kneading at 200 to 300 ° C. once using an extruder, and the obtained pellet is subjected to injection molding, extrusion molding, or the like. Can be formed by a known method.
The methacrylic resin used at this time is not particularly limited, but 80 to 100% by weight of methyl methacrylate,
Examples include 0 to 20% by weight of an alkyl acrylate having an alkyl group having 8 or less carbon atoms and 0 to 20% by weight of a vinyl monomer copolymerizable therewith. Examples of the alkyl acrylate having an alkyl group having a carbon number of 8 or less and the copolymerizable vinyl monomer include those described above.

The mixing ratio of the impact-resistant acrylic polymer in pellet form and the methacrylic resin is not particularly limited.
Depending on the required physical properties, all of them may be impact-resistant acrylic polymers. However, if the content of the rubber-like elastic material is too high, the fluidity at the time of melting becomes poor and the moldability deteriorates. Therefore, the content of the rubber-like elastic material in the compounded resin composition is preferably 50% by weight or less. .

[0061]

The present invention will be described below with reference to examples. In the examples, "parts" represents "parts by weight", and "%" other than the total permeability and the haze value represents "% by weight".

The molding of the flat plate used for evaluation in the examples and various evaluations were performed under the following conditions.

1. Molding condition Injection molding machine: V-17-65 screw type automatic injection molding machine manufactured by Japan Steel Works, Ltd. Injection molding condition: cylinder temperature 250 ° C, injection pressure 700
kg / cm ² Specimen size: 110 mm x 110 mm x 2
mm (thickness), test piece is 70 mm x 12.5 mm x
6.2 mm (thickness) Evaluation method (1) Moisture content (%) About 5 g of the water-containing polymer was precisely evaluated (W _W ), and then dried with hot air at 180 ° C. for 1 hour, and the dry weight (W _D ) was measured. Water content (%) = [(W _W −W _D ) / W _D ] × 100 (2) Measurement of average particle size of coagulated powder 63 μm, 106 μm, 212 μm, 300 μ of openings
m, 500 μm, 850 μm, 1400 μm, 2000
μm sieves are placed one on top of the other with the large opening on top,
A saucer was placed at the bottom. 24 hours at 75 ° C.
About 10 g of the dried powder obtained by drying for a time was placed in the uppermost stage of the stacked sieve, and sieved by an electric vibrator for 30 minutes. Thereafter, the weight of the powder above the sieves at each stage was measured, and the weights passing under the openings of the sieves were integrated to obtain the average particle size with respect to the sample weight.

(3) Fine amount of coagulated powder (212 μm or less)
Measurement was performed in the same procedure as in (2) above, and the ratio to the sample weight was determined from the weight of the powder that passed through the 212 μm sieve.

(4) Measurement of Pore Volume The dried powder obtained by drying the wet polymer at 75 ° C. for 24 hours was used as a sample. After about 0.12 g of this sample was precisely evaluated, it was placed in a glass capillary, evacuated for 30 minutes to form a vacuum, and then the capillary was filled with mercury and measured using a porosimeter (Amco Model 2000).

(5) Dewatering Rate of First Dewatering Section in Press Dewatering Extrusion The liquid amount per hour (Wa) discharged from the dewatering slit (4 in FIG. 1) is determined and supplied per hour. The water content (Wb) contained in the water-containing polymer (X) was determined by the following equation. Dehydration rate (%) = (Wa / Wb) × 100 (6) Compressive dewatering / extrusion limit processing amount While keeping the screw rotation speed at the time of compressive dewatering / extrusion, gradually increase the supply amount of the water-containing polymer (X). The amount of polymer treatment (dry base) when water discharged from the dewatering slit (4 in FIG. 1) stopped flowing was defined as the limit treatment amount.

(7) Molded Appearance The test pieces were visually evaluated according to the following criteria.非常 Very good ○ Good △ Slightly poor × Bad (8) Total transmittance (total light transmittance) Using a test piece, the total transmittance was measured in accordance with ASTM D-1003.

(9) Cloud Value The cloud value was measured using a test piece in accordance with ASTM D-1003.

(10) Using a YI test piece in accordance with ASTM D-1925, Y
I was measured.

(11) Izod Impact Strength (With Notch) Izod impact strength was measured using a test piece in accordance with ASTM D-256.

(12) Thermal Decomposition Resistance The residual methyl methacrylate monomer in the test piece was measured using a gas chromatograph manufactured by Shimadzu Corporation and GC-8A. Degradability was evaluated.

○ Less than 0.2% △ 0.2 to 0.4% × 0.4% or more (13) Weather resistance The test piece was exposed outdoors for 30 days, and the appearance of the test piece at that time was visually observed as follows. Was evaluated for the weather resistance.

○ Good (less coloring) △ Somewhat poor (coloring) × Bad (significant coloring) (14) Content of acetone-insoluble portion of pellets About 1 g of impact-resistant acrylic polymer pellets were precisely weighed (W
1) Then, 50 ml of acetone was added, and the mixture was allowed to stand overnight.
And centrifuged at 4 ° C., 14000 rpm for 30 minutes. Then, after removing the supernatant, 50 ml of acetone was added, and the mixture was vibrated for 30 minutes with an ultrasonic vibrator.
Centrifuge at 14000 rpm for 30 minutes. again,
After repeating this operation, the supernatant is removed and air-dried overnight. After vacuum drying at 80 ° C. for 5 hours, the mixture is cooled in a desiccator, and the weight of the residue is precisely weighed (W2). The content of the acetone-insoluble portion is calculated by the following equation.

Acetone-insoluble part (%) = (W2 / W1) × 100 (15) Amount of residual alkaline earth metal After about 2 g of impact-resistant acrylic polymer pellets were scrutinized, they were placed on a platinum dish and completely heated with an electric heater. Ashed. afterwards,
Pure water and hydrochloric acid were added to a 100-ml volumetric flask, and the volume was adjusted to a test solution. This was quantified by the atomic absorption method.
(In the examples, the amount of Ca was measured because calcium acetate was used as a coagulant.) Press Dewatering Extruder The press dewatering extruder composed of the above-described barrel of FIG. 1 and the screw of FIG. 2 was used.

Press dewatering extruder: TEM-35B manufactured by Toshiba Machine Co., Ltd.
Biaxial type Barrel diameter: 35 mm Screw length: 1244 mm Screw rotation speed: 50 to 400 rpm Screw configuration: shown in FIG.

Dewatering slit gap: 0.2 mm Cylinder set temperature: described in Examples Barrel block temperature: No. 1, No. 2, No. 5,
No. 7 Normal temperature Degassing pressure: 1st degassing port, 2nd degassing port Normal pressure [Example 1] After charging 300 parts of deionized water into a stainless steel reaction vessel, it was heated to an internal temperature of 80 ° C. At this point, the mixture (a) having the following composition ratio was charged.

Mixture (a): deionized water 5.0 parts formaldehyde sodium sulfoxylate dihydrate (hereinafter Rongalit) 0.48 parts ferrous sulfate 0.4 × 10 ⁻⁶ parts disodium ethylenediaminetetraacetate After holding at 1.2 × 10 ⁻⁶ parts for 15 minutes, a mixture (b) having the following composition ratio, which had been replaced with nitrogen in advance, was added dropwise over 2 hours, and polymerization was carried out at 80 ° C. for 1 hour. The polymerization rate of the obtained latex was 99% or more.

Mixture (b): methyl methacrylate 21.6 parts (54.0%) styrene 2.0 parts (5.0%) n-butyl acrylate 16.4 parts (41.0%) 1,3-butyl Range methacrylate 1.1 parts diallyl maleate 0.14 parts t-butyl hydroperoxide 0.08 parts sodium mono-n-pentylphenylhexaoxyethylene phosphate and sodium di-n-pentylphenylhexaoxyethylene phosphate : 1 mixture (hereinafter referred to as emulsifier Z) 1.20 parts Subsequently, the mixture (c) having the following composition ratio was charged into the reactor, and the mixture was maintained for 15 minutes. (d) was added dropwise over 3 hours and polymerized for 3 hours to obtain an acrylic rubber-like elastic latex having a multilayer structure. The polymerization rate of the obtained latex was 99% or more, and the particle size was 0.25 μm.

Mixture (c): Rongalit 0.2 part Deionized water 5.0 parts Mixture (d): Styrene 10.0 parts (16.7%) n-butyl acrylate 50.0 parts (83.3%) 1,3-butylene methacrylate 0.2 part Diallyl maleate 1.0 part Cumene hydroperoxide 0.17 part Emulsifier Z 1.8 parts Next, the mixture (e) having the following composition ratio is charged into the reactor. After holding for 30 minutes, a mixture (f) having the following composition ratio, which had been replaced with nitrogen in advance, was added dropwise over 2 hours, and further polymerized for 1 hour to obtain an acrylic multi-layer polymer latex (L-1). . The polymerization rate of the obtained latex (L-1) was 99% or more, and the particle size was 0.27 μm.

Mixture (e): Rongalit 0.2 part Deionized water 5.0 parts Mixture (f) Methyl methacrylate 57.0 parts (95%) Methyl acrylate 3.0 parts (5%) t-butyl hydroperoxide 0.1 part n-octyl mercaptan 0.39 part A 1.8% aqueous calcium acetate solution is charged into a stainless steel container as a collecting agent, and the mixture is heated to 90 ° C. with mixing and stirring, and the latex (L-1) previously produced therefrom. The linear velocity 0.4 ~
It was added continuously at 0.5 m / sec and then held for 30 minutes. After cooling to room temperature, the solidified polymer was separated by filtration with a centrifugal dehydrator while washing with 7 times by weight of pure water per polymer weight, and a white acrylic multilayer structure polymer having a water content of 45% (A- 1) was obtained. Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-1).

Next, an acrylic multi-layer polymer (A-
1) was supplied to a compression dewatering extruder under the following conditions, and the pelletized impact-resistant acrylic polymer (rubber-like elastic body content 6
2.5%, acetone insoluble content 75%). The pellet had a completely melted and good shape without bubbles.

Press Dewatering Extrusion Conditions Cylinder temperature: C1 = 120 ° C. (barrel block N
o. 3), C2 = 140 ° C. (barrel block No.
4), C3 = 170 ° C. (barrel block No. 6), C
4 = 250 ° C. (barrel block No. 8), C5 = 25
0 ° C. (barrel block No. 9, No. 10), die temperature: 250 ° C., screw rotation speed: 300 rpm, raw material supply amount: 12.0 kg / hr (dry base) Resin temperature: TR-1 = 150 ° C., TR -2 = 180 ° C,
TR-3 = 255 ° C. Dewatering rate in the first dewatering section: 65% Pressing dewatering extrusion processing capacity (300 rpm): 14.3 k
g / hr (dry base) Then, 1600 parts of the pellets and a methacrylic resin [ACRYPET (registered trademark) VH manufactured by Mitsubishi Rayon Co., Ltd.] 2
The mixture with 400 parts was mixed with a screw-type extruder having an outer diameter of 40 mm [P-40-26AB-V manufactured by Nippon Steel Works, Ltd.
Mold, L / D = 26], cylinder temperature 200 ~
The mixture was melt-kneaded at 260 ° C. and a die temperature of 250 ° C. and pelletized to obtain an impact-resistant acrylic resin having a rubber-like elastic material content of 25%, and injection molding was performed.
It was shown to.

Example 2 Example 1 was repeated except that the amount of n-octyl mercaptan in the mixture (f) was changed to 0.18 part.
In the same manner as in the above, an acrylic multilayer structure polymer latex (L-2) and a white acrylic multilayer structure polymer (A-2) having a water content of 53% were obtained. Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-2).

Next, the acrylic multilayer polymer (A-
2) was supplied to a compression dewatering extruder under the following conditions, and the pelletized impact-resistant acrylic polymer (rubber-like elastic body content 6
2.5%, 89% acetone-insoluble matter). The pellet had a completely melted and good shape without bubbles.

Compression Dewatering Extrusion Conditions The cylinder temperature, the die temperature, and the screw rotation speed were the same as in Example 1. Raw material supply amount: 12.5 kg / hr (dry base) Resin temperature: TR-1 = 147 ° C., TR-2 = 185 ° C.
TR-3 = 257 ° C. Dehydration rate in the first dehydrating section: 62% Pressing dehydration / extrusion limit processing amount (300 rpm): 14.0 k
g / hr (dry base) Next, a mixture of 1600 parts of the pellets and 2400 parts of a methacrylic resin (ACRYPET VH) was melt-kneaded under the same conditions as in Example 1 to form pellets. Was obtained, and injection molding was performed. The evaluation results are shown in Table 2.

Example 3 20.0 parts (50.0%) of methyl methacrylate, 0.0 part (0.0%) of styrene and methyl acrylate in place of n-butyl acrylate in the mixture (b) And 20.0 parts (50.0%) of n-octyl mercaptan in the mixture (f).
A water content of 60 was obtained in the same manner as in Example 1 except that the water content was 60 parts.
% Of a white acrylic-based multilayer structure polymer (A-3). Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-3).

Next, the acrylic multilayer polymer (A-
3) was supplied to a compression dewatering extruder under the following conditions, and a pellet-shaped impact-resistant acrylic polymer (rubber-like elastic body content 6
(2.5%, acetone insoluble content: 96%). The pellet had a completely melted and good shape without bubbles.

Compressive dewatering / extrusion conditions Cylinder temperature, die temperature, screw rotation speed are the same as in Example 1. Raw material supply rate: 11.5 kg / hr (dry base) Resin temperature: TR-1 = 135 ° C., TR-2 = 175 ° C.
TR-3 = 252 ° C. Dehydration rate in the first dehydrating section: 62% Pressurized dehydration extrusion processing capacity (300 rpm): 14.3 k
g / hr (dry base) Next, a mixture of 1600 parts of the pellets and 2400 parts of a methacrylic resin (ACRYPET VH) was melt-kneaded under the same conditions as in Example 1 to form pellets. Was obtained, and injection molding was performed. The evaluation results are shown in Table 2.

Example 4 0.07 parts of t-butyl hydroperoxide in the mixture (b), 76.0 parts (95.0%) of methyl methacrylate in the mixture (f),
The water content was 55 in the same manner as in Example 1 except that 4.0 parts (5.0%) of methyl acrylate, 0.15 parts of t-butyl hydroperoxide, and 0.25 parts of n-octyl mercaptan were used. % Of a white acrylic-based multilayer structure polymer (A-4). Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-4).

Next, an acrylic multilayer polymer (A-
4) was fed to a compression dewatering extruder under the following conditions, where the pelletized impact-resistant acrylic polymer (rubber-like elastic body content 5
(5.6%, acetone insoluble content: 93%). The pellet had a completely melted and good shape without bubbles.

Compressive dewatering / extrusion conditions Cylinder temperature, die temperature, screw rotation speed were the same as in Example 1. Raw material supply amount: 13.2 kg / hr (dry base) Resin temperature: TR-1 = 153 ° C., TR-2 = 182 ° C.
TR-3 = 260 ° C. Dehydration rate in the first dehydrating section: 62% Pressing dehydration extrusion limit throughput (300 rpm): 13.8 k
g / hr (dry base) Next, a mixture of 1800 parts of the pellets and 2200 parts of a methacrylic resin (Acrypet VH) is melt-kneaded under the same conditions as in Example 1 to form pellets, and an acrylic rubber-like elastic material is prepared. An impact-resistant acrylic resin having a content of 25% was obtained, injection molded, and the evaluation results are shown in Table 2.

Example 5 In the mixture (f), 19.0 parts (95.0%) of methyl methacrylate, 1.0 part (5.0%) of methyl acrylate, and 0 part of t-butyl hydroperoxide were used. In the same manner as in Example 1 except that 0.04 parts and 0.0 part of n-octylmeraptan were used, a white acrylic multilayer polymer having a water content of 43% (A-
5) was obtained. Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-5).

Next, an acrylic multi-layer structure polymer (A-
5) was supplied to a compression dewatering extruder under the following conditions to obtain a pellet-shaped impact-resistant acrylic polymer (acrylic rubber-like elastic material content: 83.3%, acetone-insoluble content: 95%). The pellet had a completely melted and good shape without bubbles.

Conditions for pressing, dewatering and extrusion Cylinder temperature: C1 = 120 ° C. (barrel block N
o. 3), C2 = 130 ° C. (barrel block No.
4), C3 = 160 ° C. (barrel block No. 6), C
4 = 230 ° C. (barrel block No. 8), C5 = 23
0 ° C. (barrel block No. 9, No. 10), die temperature: 240 ° C., screw rotation speed: 300 rpm, raw material supply amount: 12.6 kg / hr (dry base) Resin temperature: TR-1 = 165 ° C., TR -2 = 190 ° C,
TR-3 = 248 ° C. Dehydration rate in the first dehydrating section: 62% Compressive dehydration extrusion processing capacity (300 rpm): 14.0 k
g / hr (dry base) Next, a mixture of 1205 parts of the pellets and 2795 parts of a methacrylic resin (Acrypet VH) was melt-kneaded under the same conditions as in Example 1 to form pellets. An impact-resistant acrylic resin having a content of 25% was obtained, injection molded, and the evaluation results are shown in Table 2.

Example 6 The latex (L-2) produced in Example 2 was charged with a 2.6% aqueous solution of magnesium sulfate as a collecting agent, and the mixture was heated to 90 ° C. with mixing and stirring. Was continuously added at a linear velocity of 0.4 to 0.5 m / sec, and then held for 30 minutes. After cooling to room temperature, the solidified polymer was filtered with a centrifugal dehydrator while washing with 7 times of pure water per polymer to obtain a white acrylic multilayer structure polymer (A-6) having a water content of 84%. Obtained. Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-6).

Next, an acrylic multilayer polymer (A-
6) the same cylinder temperature and die temperature as in Example 2,
The mixture was fed to a compression dewatering extruder under the conditions of the screw rotation speed.
Although good melted pellets were obtained, the critical throughput was as small as 8.0 kg / hr (dry base).

Example 7 The latex (L-2) prepared in Example 2 was charged with a 2.6% aqueous solution of magnesium sulfate as a collecting agent, and the mixture was heated to 90 ° C. with mixing and stirring. Was continuously added at a linear velocity of 0.4 to 0.5 m / sec, and then held for 30 minutes. Further, the slurry obtained here was transferred to a GL kettle capable of pressure treatment, and kept at 130 ° C. for 30 minutes under pressure. After cooling to room temperature, the solidified polymer was filtered with a centrifugal dehydrator while washing with 7 times the weight of pure water per polymer weight, and the water content was 3%.
8% white acrylic multi-layer polymer (A-7)
I got Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-7).

Next, an acrylic multi-layer polymer (A-
7) the same cylinder temperature and die temperature as in Example 2,
The mixture was fed to a compression dewatering extruder under the conditions of the screw rotation speed.
Good pellets completely melted were obtained, and the limit throughput was 13.8 kg / hr (dry base), which was almost the same as that of Example 2.

Example 8 The latex (L-2) produced in Example 2 was charged with a 1.8% aqueous calcium acetate solution as a collecting agent, and the mixture was heated to 90 ° C. with mixing and stirring. Was continuously added at a linear velocity of 0.4 to 0.5 m / sec, and then held for 30 minutes. After cooling to room temperature, the solidified polymer was separated by filtration with a centrifugal dehydrator while washing with 7 times by weight of pure water per polymer weight. Furthermore, this polymer was stirred using a large Henschel mixer,
A finely pulverized white acrylic multilayer structure polymer (A-8) having a water content of 53% was obtained. Table 1 shows the solidified powder properties of the acrylic multilayer polymer (A-8).

Next, the acrylic multilayer polymer (A-
8) the same cylinder temperature and die temperature as in Example 2,
The mixture was fed to a compression dewatering extruder under the conditions of the screw rotation speed.
Although good pellets that were completely melted were obtained, the critical throughput was as small as 7.0 kg / hr (dry base).

Example 9 The acrylic multi-layer polymer (A-2) obtained in Example 2 and a phosphorus compound tris (2,4-di-t-butylphenyl) phosphite [Asahi Denka Kogyo Co., Ltd. Manufactured by Adeka Stab 2112) was continuously supplied to a compression dehydration extruder so as to have the compounding amount shown in Table 3, and was shaped under the same extrusion conditions as in Example 2 to obtain a pellet-shaped impact-resistant acrylic resin. A polymer was obtained. Next, this pellet was blended with a methacrylic resin (Acrypet VH) under the same conditions as in Example 2 to obtain an impact-resistant acrylic resin having an acrylic rubbery elastic body content of 25%, and injection molding was performed. Table 3 shows the evaluation results.

[Examples 10 to 15] Using the acrylic multilayer polymer (A-2) obtained in Example 2, the kind of the organic stabilizer (Y) and the compounding amount thereof are shown in Table 3. Acrylic resin pellets were obtained in the same manner as in Example 9 except for changing to. Next, the pellets and a methacrylic resin (Acrypet VH) were blended in the same manner as in Example 2 to obtain an impact-resistant acrylic resin having an acrylic rubber-like elastic body content of 25%, and injection molding was performed. Table 3 shows the evaluation results.

Example 16 The latex (L-2) produced in Example 2 was coagulated under the same conditions as in Example 2 to obtain a slurry. After cooling to room temperature, the solidified polymer was filtered with a centrifugal dehydrator while washing with pure water three times the weight of the polymer to obtain a white acrylic multi-layer polymer (A-16).

Next, an acrylic multilayer polymer (A-1)
6) the same cylinder temperature and die temperature as in Example 2,
The mixture was supplied to a compression dehydration extruder under the conditions of the screw rotation speed, and impact-resistant acrylic polymer pellets were obtained in the same manner as in Example 9. Next, the pellets and a methacrylic resin (Acrypet VH) were blended in the same manner as in Example 2 to obtain an impact-resistant acrylic resin having an acrylic rubbery elastic body content of 25%, followed by injection molding. Was. A slightly yellowish color was observed in this molded plate. Table 2 shows the evaluation results.

Example 17 The acrylic multi-layer polymer (A-2) obtained in Example 2 was subjected to a compression dehydration extruder under the same conditions as in Example 2 for the cylinder temperature, die temperature and raw material supply amount. Supplied. When the number of revolutions of the screw was set to 330 rpm, the dewatering rate of the first dewatering section became 50%, and bubbles were observed in the obtained pellets.

Example 18 The acrylic multi-layered polymer (A-2) obtained in Example 2 was subjected to a press dehydration extruder under the same conditions as in Example 2 for the cylinder temperature, die temperature and raw material supply amount. Supplied. When the screw rotation speed was set to 380 rpm, the dewatering rate of the first dewatering section became 40%, and the resulting pellets contained more air bubbles than in Example 17.

[0107]

[Table 1]

[0108]

[Table 2]

[0109]

[Table 3]

[0110]

The pellet-shaped impact-resistant acrylic polymer of the present invention has excellent handling properties and a large content of rubber-like elastic material.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a twin-screw dewatering extruder used in the present invention.

FIG. 2 is a screw configuration diagram used in the twin-screw dewatering extruder of FIG.

[Explanation of Codes] Barrel 2. Raw material input port 3. Hopper 4.5.6. Dewatering slit 7. First vent port 8. Second deaeration port 9. Dice 10. Screw 11. Length adjustment color No. 1 to No. 10 Barrel Block TR-1, TR-2, TR-3 Thermocouple for Resin Temperature Measurement

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08F 220: 12)

Claims (5)

[Claims] 1. A large number of acrylic multi-layered polymers having at least one rubber-like elastic layer (α) as an inner layer and a hard polymer layer (β) containing methyl methacrylate as a main component as an outermost layer. In the pellet-shaped impact-resistant acrylic polymer, the content of the acetone-insoluble portion including the rubber-like elastic layer (α) is 70 to 9 per unit weight of the pellet.
An impact-resistant acrylic polymer in the form of a pellet, which is 7% by weight. 2. The impact-resistant article according to claim 1, wherein the proportion of the rubber-like elastic body contained in the pellet-shaped impact-resistant acrylic polymer is 50 to 90% by weight per unit weight of the pellet. Acrylic polymer. 3. A hard polymer layer (β) having a glass transition temperature (hereinafter abbreviated as Tg) of 25 ° C. or less when the polymer constituting the rubber-like elastic layer (α) is polymerized alone. 3. The impact-resistant acrylic polymer according to claim 1, wherein Tg when the polymer is polymerized alone is 50 ° C. or higher. 4. 4. The rubber-like elastic layer (α) is an alkyl acrylate having an alkyl group having 8 or less carbon atoms.
0.1 to 10 parts by weight of a graft crosslinking agent per 100 parts by weight of a monomer mixture consisting of 10 to 60% by weight of a monofunctional monomer having at least one vinyl group copolymerizable therewith. And a polymer prepared from 0.1 to 10 parts by weight of a polyfunctional crosslinking agent having at least two vinyl groups, wherein the hard polymer layer (β) has an alkyl group having 4 or less carbon atoms. 60 ~
The polymer according to any one of claims 1 to 3, comprising a polymer produced from 100% by weight and 0 to 40% by weight of an unsaturated monomer copolymerizable therewith. Impact-resistant acrylic polymer. 5. The anti-resistant film according to claim 1, wherein the ratio of the hard polymer layer (β) in the acrylic multi-layer structure polymer is 10 to 50% by weight. Impact acrylic polymer.