JPH10237263A - Acrylic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having good weather ability, fire resistance and shape retention by mixing a thermoplastic acrylic copolymer selected from among branched copolymers having a comb or star skeleton and (A-B-A)n or (A-B)n block copolymers with a mixture of a phosphorus compound with a neutralized expandable graphite in a specified ratio and an inorganic filler. SOLUTION: The comb skeleton copolymer is a copolymer of a macromonomer having a polymerizable (meth)acrylate group at one end and having a non-polymerizable polymer at the other end with an acrylic ester. The star-skeleton copolymer is a copolymer of a (meth)acrylic ester having an alkyl ester as a side chain with a monomer. In the (A-B-A)n or (A-B)n block copolymer, A is a vinyl polymer block, and B is a (meth)acrylic ester structural unit. 100 pts.wt. thermoplastic acrylic polymer is mixed with 20-200 pts.wt. phosphorus compound/graphite mixture and 50-500 pts.wt. filler. The ratio of the graphite to the phosphorus compound is 9/1 to 1/100 by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an acrylic resin composition, and more particularly to an acrylic resin composition having fire resistance.

[0002]

2. Description of the Related Art In the field of building materials, fire resistance has conventionally been required by regulations such as the Building Standards Law. On the other hand, resin materials have been widely used as building materials with the recent expansion of applications, and resin materials having fire resistance have been required.

For such fire resistance, not only the resin material itself is not easily burned, but also such a property that the flame is not sent to the back surface is required. Since the resin component and the organic component in the resin material inherently have the property of burning or melting, it is important performance how long they are kept without burning or melting for a long time.

[0004] For this reason, various techniques for blending inorganic components to impart fire resistance have been proposed, but inorganic components having no self-adhesiveness tend to fall off, and as a result, a flame enters the back surface. Therefore, there is a problem of how long it will not fall off.

[0005] For example, JP-A-6-25476 discloses a resin composition in which red phosphorus or a phosphorus compound and thermally expandable graphite are added to a polyolefin resin. Since this resin composition has sufficient flame retardancy when viewed from the oxygen index, it can be said that the resin composition is a material that is difficult to burn.

However, when used in the coating applications required in the construction field, such as coating steel frames, coating the back surface of an outer wall, and coating the back surface of a partition, it is sufficient if the material itself does not burn easily. In addition, it is required to have a performance of not increasing the temperature of the coated surface in contact with the flame.

On the other hand, the above-mentioned conventional resin composition cannot satisfy the criteria of keeping the temperature of the back surface at 260 ° C. or lower for 30 minutes in a fire resistance test or a fire resistance test (not enough fire resistance), There is a problem that the function as a heat insulating layer is lost at an early stage because only the brittle ash is present and the residue falls off (insufficient shape retention).

Further, a method of blending aluminum hydroxide or antimony trioxide with an acrylic resin has also been proposed, but the flame retardancy is insufficient, and it can withstand a standard of 30 minutes in a fire test or a fire test. could not.

As described above, there is no proposal in the prior art for a resin composition capable of simultaneously satisfying fire resistance and shape retention, and as a fire resistance performance in the field of building materials where there is a great demand for such materials. Since the required standard cannot be satisfied, there has been a problem that the intended use is limited and it cannot be used alone as a wall backing material, a steel frame covering material, or the like.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a material which has excellent weather resistance, has sufficient fire resistance during combustion, and has a good shape retention, so that it can be used more widely. An object of the present invention is to provide an acrylic resin composition that can be applied to places where fire resistance is required, such as coating, and can maintain fire insulation and heat resistance for a certain period of time.

[0011]

The acrylic resin composition of the present invention comprises a branched copolymer having a comb-shaped skeleton, a branched copolymer having a star-shaped skeleton, and an (ABA) _n- type. 100 weight of at least one thermoplastic acrylic copolymer selected from a block copolymer and (AB) _n- type block copolymer, the total of a phosphorus compound and a neutralized thermally expandable graphite 20 to 200 parts by weight, and 50 to 500 parts by weight of an inorganic filler, wherein the weight ratio of the neutralized thermally expandable graphite to the phosphorus compound is 9: 1 to 1: 100. And

Hereinafter, the present invention will be described in detail. The thermoplastic acrylic copolymer used in the present invention includes a branched copolymer having a comb-shaped skeleton, a branched copolymer having a star-shaped skeleton, an (ABA) _n- type block copolymer, And (AB) at least one selected from _n- type block copolymers.

Acrylic resins are resins having better weather resistance and the like than polyolefin resins and the like, and are also excellent in elastomeric properties and adhesiveness. Acrylic resins used as elastomers and pressure-sensitive adhesives are usually high molecular weight polymers having a weight average molecular weight of 500,000 to 1,000,000. When used as an elastomer, extrusion molding is used. When used as an adhesive, a solution or water dispersion is used. It is applied in a liquid state.

In such a high molecular weight material, when a large amount of filler is to be blended, the filler is deposited on the surface during extrusion molding and drying, and not only does not obtain tackiness, but also various elongation states. Was obtained, and especially when an inorganic compound was compounded, only about 10 parts by weight could be compounded with respect to 100 parts by weight of the resin.

The thermoplastic acrylic copolymer used in the present invention has a low viscosity at the time of melting, and can provide a beautiful molded article having a smooth surface even when a large amount of fillers and other compounds are blended. it can. For this reason, it is possible to form a molded article containing a sufficient amount of a phosphorus compound, neutralized heat-expandable graphite, and an inorganic filler in order to exhibit fire resistance. It is particularly suitable for obtaining joint materials, fire-resistant covering materials, fire-resistant damping materials and the like.

The branched copolymer having the comb-shaped skeleton is as follows:
It has a polymerizable (meth) acrylate group at one end,
At the other end, so-called macromonomers 5 to 3 having a non-polymerizable polymer having a weight average molecular weight of 2000 to 60000
It can be obtained by copolymerizing 0% by weight and 40 to 95% by weight of a (meth) acrylate having an alkyl group having 4 to 12 carbon atoms in a side chain. Further, a copolymerizable monomer other than the above may be contained up to 30% by weight.

As the above-mentioned macromonomer, those sold by Toa Gosei Chemical Co. or the like can be used. It is preferable to use a macromonomer having a glass transition temperature of 50 ° C. or higher of the non-polymerizable polymer at the terminal.

Examples of the branched copolymer having a star-shaped skeleton include: 70 to 95% by weight of a (meth) acrylate having an alkyl group having 4 to 12 carbon atoms in a side chain, and a copolymerizable monomer. A copolymer consisting of 30 to 5% by weight is preferred.

The branched copolymer having a star-shaped skeleton is as follows:
A mixed monomer consisting of a (meth) acrylate having a C 4-12 alkyl group in the side chain and a monomer copolymerizable with the (meth) acrylate is mixed in the presence of a polyfunctional chain transfer agent. To perform a first-stage polymerization reaction, and further, a copolymerizable monomer is charged, and a second-stage reaction is performed. Alternatively, the reaction order of the first and second stages may be changed so that the (meth) acrylate copolymer is formed in the second stage.

Examples of the (meth) acrylate having an alkyl group having 4 to 12 carbon atoms in the side chain include, for example, ethyl (meth) acrylate and n- (meth) acrylate.
-Butyl, 2-ethylhexyl (meth) acrylate, n-octyl acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, lauryl (meth) acrylate and the like are used alone. Or two or more of them may be used in combination.

When the number of carbon atoms of the alkyl group of the (meth) acrylate is 3 or less or 13 or more, the obtained thermoplastic acrylic copolymer becomes too hard.
The initial tack decreases.

The monomer to be copolymerized with the (meth) acrylic acid ester is used for increasing the cohesive strength of the acrylic copolymer, and is preferably a monomer having a polar group. As the monomer having a polar group, for example,
(Meth) acrylic acid, itaconic acid, crotonic acid, (anhydride) maleic acid, fumaric acid, carboxyethyl (meth)
Carboxyl group-containing monomers such as acrylates; hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl acrylate, modified caprolactone (meth) acrylate, polypropylene glycol (meth) acrylate, and polyethylene glycol (meth) acrylate; acrylonitrile , N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyllaurylolactam, acryloylmorpholine, (meth)
In addition to highly polar monomers such as acrylamide, dimethylaminoethyl (meth) acrylate, dimethyl (meth) acrylamide and other amino groups and amide group-containing monomers,
Medium polar monomers such as vinyl acetate, styrene, methyl (meth) acrylate and the like. These monomers may be used alone or in combination of two or more.

The monomer used in the second stage is preferably one in which the (co) polymer formed by the second stage reaction has a glass transition temperature of 50 ° C. or higher.

Examples of the polyfunctional chain transfer agent include trifunctional mercaptans such as trithioglycerin, trimethylolpropane trithioglycolate, and trimethylol trithiopropionate; pentaerythritol tetrakisthioglycolate and pentaerythritol tetrakisthioprolate. One or more selected from polyfunctional mercaptans such as tetrafunctional mercaptans such as pionates may be used.

The above (ABA) _n type and (AB) _n
In the block copolymerization, A represents a vinyl polymer block, and B represents a general formula CH ₂ ＣＲCR ¹ COOR ² (wherein
R ¹ represents a hydrogen atom or a methyl group, and R ² has 2 to 2 carbon atoms.
(Indicating an alkyl group of 14) as a structural unit.

Examples of the vinyl compound forming the vinyl polymer block portion (A block portion) represented by A include styrene, methyl methacrylate, α-methyl styrene, o-methyl styrene, p-methyl styrene, and ethyl methacrylate. , N-propyl methacrylate, acrylonitrile, vinyl acetate, and the like. Particularly, styrene and methacrylate are preferably used.

The glass transition temperature (T
g) is at 20 ° C. for good cohesion and tackiness.
Or more, more preferably 50 ° C. or more.

Examples of the acrylate having an alkyl group having 2 to 14 carbon atoms, which forms the (co) polymer block (B block portion) represented by B, include:
N-butyl acrylate, isobutyl acrylate, ter-butyl acrylate, isoamyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, lauryl acrylate, and the like, which may be used alone, Two or more kinds may be used in combination.

Examples of the methacrylate having an alkyl group having 2 to 14 carbon atoms forming the B block portion include n-octyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and the like. These may be used alone or in combination of two or more.

The above (ABA) _n type and (AB) _n
The above-mentioned monomer having a polar group may be copolymerized with the mold block copolymer in order to balance the tackiness and adhesiveness.

The above block copolymer can be produced, for example, by the method described in JP-B-59-33148. That is, by polymerizing the acrylic monomer mixture using a chain transfer agent having a hydroxyl group or a halogen group, a polymerization initiator, and further reacting a polyfunctional isocyanate compound or the like, a terminal reactive copolymer can be obtained. it can.

The amount of the (meth) acrylate used in the thermoplastic acrylic copolymer is from 40 to 40%.
99.5% by weight is preferred. If the amount of the (meth) acrylic acid ester is less than 40% by weight, the cohesive force of the thermoplastic acrylic copolymer becomes too high and the initial tackiness is reduced. If it exceeds 99.5% by weight, the cohesive force is low. Because of this, sufficient holding power cannot be obtained.

Further, in the constituent components of the thermoplastic acrylic copolymer, the amount of the polar group-containing monomer used is as follows:
It is preferably at most 30% by weight of all monomers. If the amount used exceeds 30% by weight, the cohesive force becomes too high, and the initial tackiness decreases.

As a method for obtaining a thermoplastic acrylic copolymer from the above constituent components, for example, polymerization methods such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization and the like can be employed, but (meth) acrylic acid Solution polymerization is preferred because it has good copolymerizability with a carboxyl group-containing monomer such as the above, easily controls the coating viscosity, and easily mixes and mixes a crosslinking agent and a tackifier resin.

As the polymerization initiation method, a known polymerization initiation method such as a thermal polymerization method in which radicals are generated by heating; and an ultraviolet polymerization method in which radicals are generated by irradiation with ultraviolet rays can be used. When the thermal polymerization method is used, as a polymerization initiator, for example, a peroxide such as benzoyl peroxide;
An azobis compound such as 2,2′-azobisisobutyronitrile can be used. In obtaining the acrylic copolymer, a chain transfer agent may be added to the mixed monomer solution of the constituent components for the purpose of suppressing the variation in the polymerization reaction and appropriately controlling the molecular weight.

Examples of the above chain transfer agent include thiols such as n-dodecyl mercaptan and t-dodecyl mercaptan and halogen compounds such as carbon tetrachloride.

When the weight-average molecular weight (Mw) of the thermoplastic acrylic copolymer obtained as described above is small, sufficient cohesive strength cannot be obtained, and when it is large, the solution viscosity increases and the polymerizability and coatability become poor. Since it decreases, it is preferably from 100,000 to 1.5 million, more preferably from 300,000 to 800,000.

The weight average molecular weight (Mw) of the thermoplastic acrylic copolymer obtained above can be determined as a standard polystyrene equivalent molecular weight by a gel permeation chromatography (GPC) method. Specifically, an uncrosslinked acrylic copolymer is converted to tetrahydrofuran (TH
A solution having a concentration of 0.1 to 0.5% by weight is prepared by dissolving in F), separated by a gel-packed column using THF as a dispersion medium, and can be determined from the elution time distribution.

As the above-mentioned thermoplastic acrylic copolymer, those having tackiness at room temperature are preferable. If a large amount of a filler or other compound is blended with the solution acrylic pressure-sensitive adhesive, the blend is deposited on the surface during solvent drying, and it is difficult to obtain a pressure-sensitive adhesive sheet having a smooth surface. However, by using a thermoplastic acrylic copolymer having a tackiness at room temperature, a sheet having a better tackiness can be obtained, which is used for a fire-resistant pressure-sensitive adhesive sheet having excellent workability. be able to.

The thermoplastic acrylic copolymer having tackiness at room temperature has one or two glass transition temperatures (Tg), one of which has a peak temperature of -70 ° C to 2 ° C.
Those in the range of 0 ° C. are preferred. If the Tg peak temperature is less than -70 ° C, the cohesive strength is too low and the adhesive strength is liable to be reduced. If the peak temperature exceeds 20 ° C, the cohesive strength becomes too large, and the adhesiveness is not exhibited at room temperature.

In particular, in order for the acrylic copolymer to exhibit tackiness, the copolymer component includes a component having a low glass transition temperature (Tg) and a component having a high glass transition temperature (Tg). It is preferable that the temperature is in the range of 20 ° C to 20 ° C and the Tg of the other component is 50 ° C or higher. Tg is 50
If the temperature is lower than ℃, it is difficult to maintain a balance between hot-melt properties and holding power.

As described above, the copolymer component having a Tg of more than 50 ° C. has a star-shaped skeleton in the branched copolymer as a portion forming a side chain in the branched copolymer having a comb-shaped skeleton as described above. Is a component to be reacted in the second stage,
In addition, a composition having room-temperature tackiness can be obtained by causing the block copolymer to be present as the component A. The proportion of the component having a high Tg is preferably 5 to 30% by weight. When the proportion of the branched chain or the block portion is less than 5% by weight, the cohesive force is reduced and it is difficult to obtain a holding force, and when it is more than 30% by weight, the cohesive force becomes too high. Properties tend to decrease.

Examples of the copolymer component having a Tg exceeding 50 ° C. include, for example, methyl methacrylate, styrene, isobornyl (meth) acrylate, α-methylstyrene and the like.

The thermoplastic acrylic copolymer includes tackifying resins such as known terpene resins, C ₅ and C ₉ petroleum resins, and rosin ester resins as long as the object of the present invention is not impaired. A stabilizer or the like may be blended.

The phosphorus compounds used in the present invention include:
There is no particular limitation, for example, red phosphorus; various phosphoric esters such as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xyenyl diphenyl phosphate;
Metal phosphate salts such as sodium phosphate, potassium phosphate and magnesium phosphate; ammonium polyphosphates; and compounds represented by the following general formula (1). Among them, ammonium polyphosphates or the following general formula (1)
The compound represented by is preferred.

[0046]

Embedded image

In the formula, R ¹ and R ³ are hydrogen, C ¹ -C 1
And 6 represents a linear or branched alkyl group or an aryl group having 6 to 16 carbon atoms. R ² is a hydroxyl group, a linear or branched alkyl group having 1 to 16 carbon atoms, a linear or branched alkoxyl group having 1 to 16 carbon atoms, an aryl group having 6 to 16 carbon atoms, The aryloxy groups of the formulas 6 to 16 are shown.

As the above-mentioned red phosphorus, commercially available red phosphorus can be used, but from the viewpoints of moisture resistance and safety such as not spontaneously igniting during kneading, it is preferable that the surface of the red phosphorus particles is coated with a resin.

The above ammonium polyphosphates include:
For example, ammonium polyphosphate, melamine-modified ammonium polyphosphate and the like can be mentioned, but ammonium polyphosphate is preferable from the viewpoint of handleability. Examples of commercially available ammonium polyphosphates include “AP462” manufactured by Hoechst and “Sumisafe P” manufactured by Sumitomo Chemical Co., Ltd.

The compound represented by the general formula (1) includes, for example, methylphosphonic acid, dimethyl methylphosphonate, diethyl methylphosphonate, ethylphosphonic acid,
Propylphosphonic acid, butylphosphonic acid, 2-methylpropylphosphonic acid, t-butylphosphonic acid, 2,3-dimethyl-butylphosphonic acid, octylphosphonic acid, phenylphosphonic acid, dioctylphenylphosphonate, dimethylphosphinic acid, methylethylphosphine Acid, methylpropylphosphinic acid, diethylphosphinic acid, dioctylphosphinic acid, phenylphosphinic acid, diethylphenylphosphinic acid, diphenylphosphinic acid, bis (4-methoxyphenyl) phosphinic acid, and the like,
These may be used alone or in combination of two or more.

The heat-expandable graphite used in the present invention is a conventionally known substance, and powders of natural scale graphite, pyrolytic graphite, quiche graphite and the like are mixed with inorganic acids such as concentrated sulfuric acid, nitric acid and selenic acid, and concentrated nitric acid. Treated with a strong oxidizing agent such as perchloric acid, perchlorate, permanganate, dichromate, hydrogen peroxide, etc. to produce a graphite intercalation compound, maintaining a carbon layered structure It is a crystalline compound as it is.

The heat-expandable graphite obtained by the acid treatment is as follows:
Further, it is neutralized with ammonia, an aliphatic lower amine, an alkali metal compound, an alkaline earth metal compound, or the like. Examples of the aliphatic lower amine include monomethylamine, dimethylamine, trimethylamine, ethylamine, propylamine, butylamine and the like. As the alkali metal compound and the alkaline earth metal compound, for example, hydroxides, oxides, carbonates such as potassium, sodium, calcium, barium, magnesium,
Sulfate, organic acid salt and the like can be mentioned. Commercial products of the heat-expandable graphite thus neutralized include, for example, “CA-60S” manufactured by Nippon Kasei Co., Ltd.

The particle size of the neutralized heat-expandable graphite is preferably 20 to 200 mesh. When the particle size is smaller than 200 mesh, the degree of expansion of graphite is small, a predetermined refractory insulation layer cannot be obtained, and when the particle size is larger than 20 mesh, there is an advantage that the degree of expansion of graphite is large,
When kneaded with the resin, the dispersibility deteriorates, and a decrease in physical properties is inevitable.

In the acrylic resin composition of the present invention,
The phosphorus compound and the neutralized heat-expandable graphite are added in a total amount of 20 to 200 parts by weight based on 100 parts by weight of the thermoplastic acrylic copolymer. If the total amount of the above two components is less than 20 parts by weight, sufficient fire resistance cannot be exhibited, and if it exceeds 200 parts by weight, the resin content becomes insufficient and the resin cannot serve as a binder. It will be difficult.

In order to provide higher refractory performance and shape retention of combustion residues, the weight ratio of the neutralized thermally expandable graphite to the phosphorus compound is set within the above range.
9: 1 to 1: 100.

By adding the neutralized heat-expandable graphite to the phosphorus compound in a weight ratio of 9: 1 to 1: 100, scattering of the expandable graphite during combustion is suppressed, Shape retention becomes possible. If the ratio of the heat-expandable graphite increases, the expanded graphite during heating is scattered, so that a sufficient heat-insulating layer cannot be obtained at the time of heating. Conversely, if the ratio of the phosphorus compound increases, the heat-insulating layer is not sufficiently formed, and The heat insulation effect cannot be obtained.

From the viewpoint of shape retention during combustion, the weight ratio of the neutralized heat-expandable graphite to the phosphorus compound is more preferably in the range of 1: 3 to 1: 100. Even if the acrylic resin composition itself is flame-retardant and the shape retention is insufficient, the brittle residue collapses and penetrates the flame, and depending on whether the shape retention is sufficient, the acrylic Applicable applications of the base resin composition are greatly different.

The inorganic filler used in the present invention includes:
Not particularly limited, for example, silica, diatomaceous earth, alumina,
Zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, ferrites, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, Barium carbonate, dawn night, hydrotalcite, calcium sulfate, barium sulfate, gypsum fiber, calcium silicate, talc, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass beads, silica Series balloon, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon fiber, carbon balloon, charcoal powder, various metal powders, potassium titanate, magnesium sulfate “MO
S ", zinc zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, stainless steel fiber, zinc borate, various magnetic powders, slag fiber, fly ash,
Fly ash balloons, shirasu, shirasu balloons, dehydrated sludge and the like may be mentioned, and these may be used alone or in combination of two or more.

Among the above-mentioned inorganic fillers, periodic table II or II
Metal salts or oxides of metals belonging to Group I are preferred in that they obtain a foamed fired product and retain their shape firmly after burning (points of high shape retention), and hydrous inorganic substances are dehydrated during heating. This is preferred in that high heat resistance can be obtained because the heat-absorbing property is exhibited. Specific examples of these include, for example, calcium carbonate, magnesium carbonate, magnesium hydroxide,
Aluminum hydroxide and the like.

In the acrylic resin composition of the present invention,
The inorganic filler is added in an amount of 50 to 500 parts by weight based on 100 parts by weight of the thermoplastic acrylic copolymer. If the addition amount of the inorganic filler is less than 50 parts by weight, sufficient fire resistance cannot be obtained, and if it exceeds 500 parts by weight, mechanical properties are greatly reduced and cannot be used. Is done.

In the present invention, as long as the physical properties of the acrylic resin composition are not impaired, phenol-based, amine-based, sulfur-based antioxidants, metal damage inhibitors, antistatic agents, stabilizers, Agents, lubricants, softeners, pigments and the like may be added.

The acrylic resin composition of the present invention can be obtained by kneading each component using a kneading device such as a single screw extruder, a twin screw extruder, a Banbury mixer, a kneader mixer, and a roll.

[0063]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Preparation of Thermoplastic Acrylic Copolymer (a) 30 parts by weight of 2-ethylhexyl acrylate (hereinafter, parts by weight are abbreviated as “parts”), n-butyl acrylate 6
0 parts, 10 parts of polymerizable polystyrene (manufactured by Toagosei Co., Ltd., trade name: Macromer AS-6, Mw = 13000), 0.15 part of n-dodecyl mercaptan as a chain transfer agent, and 80 parts of ethyl acetate as a solvent. A five-necked flask equipped with a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas inlet was charged, and purged with nitrogen gas for 30 minutes while stirring to replace air in the monomer solution and in the flask.
Next, a solution prepared by dissolving 0.03 part of azobisisobutyronitrile in 1 part of ethyl acetate as a thermal polymerization initiator was added dropwise from a dropping funnel while maintaining the temperature at 70 ° C.
After the start of the reaction, the temperature is maintained at 10 ° C under a nitrogen gas stream at the same temperature.
The reaction was carried out for an hour to obtain an acrylic copolymer solution. The obtained acrylic copolymer solution was vacuum-dried to remove the solvent and unreacted monomer, thereby preparing a branched thermoplastic acrylic copolymer (a) having a comb-shaped skeleton.

Preparation of Thermoplastic Acrylic Copolymer (b) Instead of 30 parts of 2-ethylhexyl acrylate, 60 parts of n-butyl acrylate, and 10 parts of polymerizable polystyrene, 80 parts of 2-ethylhexyl acrylate, N-vinylcaprolactam 5 Part, polymerizable polymethyl methacrylate (manufactured by Toagosei Co., Ltd., trade name: Macromer AA-10, M
(w = 24000) Polymerization and drying were carried out in the same manner as for the acrylic copolymer (a) except that 15 parts were used, to obtain a branched thermoplastic acrylic copolymer (b) having a comb-shaped skeleton. .

Preparation of thermoplastic acrylic copolymer (c) 30 parts of styrene and 1 part of trimethylolpropane triglycolate as a chain transfer agent were charged and heated to 140 ° C. After heating for 1 hour, the temperature was lowered when the conversion exceeded 80%, 40 parts of 2-ethylhexyl acrylate,
After adding 20 parts of n-butyl acrylate, 10 parts of vinyl acetate and 80 parts of ethyl acetate, purging nitrogen gas in the same manner as in the reaction of the acrylic copolymer (a), 0.03 parts of azobisisobutyronitrile was added. In addition, the reaction was carried out for 10 hours while additionally adding 0.01 parts of azobisisobutyronitrile every hour. The obtained acrylic copolymer was vacuum-dried to prepare a branched thermoplastic acrylic copolymer (c) having a star-shaped skeleton.

Preparation of thermoplastic acrylic copolymer (d) 20 parts of styrene, 20 parts of ethyl acetate, and 4,4'-azobis (4-cyano-1-pentanol) as a polymerization initiator
(Hereinafter abbreviated as ACP) 0.4 part, 0.1 part of n-dodecyl mercaptan as a chain transfer agent was used, and 80 ° C.
The polymerization was carried out in the same manner as in the acrylic copolymer (a) except that the reaction was carried out by raising the temperature. After polymerization for 15 hours, the reaction was terminated, and polystyrene having terminal hydroxyl groups was obtained. Next, 2,4
-To a 5-necked flask in which 1 part of tolylene diisocyanate was dissolved in 10 parts of toluene, 3 g of hydroxyl-terminated polystyrene was added.
It was dropped over time. After the completion of the dropwise addition, the reaction was continued for 4 hours to obtain polystyrene having terminal reactivity. On the other hand, another five-necked flask was charged with 60 parts of ethyl acrylate, 20 parts of methyl methacrylate, and 0.1 part of ACP, and then charged under a stream of nitrogen gas.
The polymerization reaction was performed at 0 ° C. for 12 hours. Next, 0.2 parts of dibutyltin dilaurate was added and the temperature was maintained at 40 ° C. Furthermore, the terminal-reactive polystyrene prepared above was added dropwise over 1 hour, and the reaction was continued for another 5 hours to obtain a block copolymer. The obtained block copolymer was dried under vacuum to prepare an acrylic copolymer (d).

Preparation of thermoplastic acrylic copolymer (e) 30 parts of 2-ethylhexyl acrylate, 60 parts of n-butyl acrylate, 10 parts of polymerizable polystyrene and n-
An acrylic copolymer (a) was used except that instead of 0.15 part of dodecyl mercaptan, 30 parts of methyl methacrylate, 60 parts of n-butyl acrylate, 10 parts of ethyl acrylate and 0.05 part of n-dodecyl mercaptan were used. Similarly, polymerization and drying were performed to prepare a thermoplastic acrylic copolymer (e) having no branch.

A thermoplastic acrylic copolymer (f) polymethyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was used.

(Examples 1 to 6 and Comparative Examples 1 to 4) 100 parts by weight of the thermoplastic acrylic copolymer obtained above were mixed with neutralized heat-expandable products in the amounts shown in Table 1 The graphite, the phosphorus compound and the inorganic filler were melt-kneaded using a kneading roll to obtain an acrylic resin composition, and then press-molded at 140 ° C. to produce a test piece for evaluation.

The test pieces for evaluation obtained in the above Examples and Comparative Examples were subjected to the following performance evaluations (1) to (3), and the results are shown in Table 1.

(1) Evaluation of Flexibility When the test piece was bent at 180 degrees, it was evaluated as follows.

(2) Evaluation of fire resistance Stainless steel plate (length 100 mm, width 100 m)
m) A test piece (length 100 mm, width 100 m)
m, cut to a thickness of 4 mm) was heated on a hot plate to 500 ° C. on one side, and the temperature of the other side (rear surface temperature) was measured and evaluated according to the following evaluation criteria.・ Back surface temperature less than 260 ℃ ○

(3) Evaluation of Adhesion The test pieces were evaluated by the ball tack method according to JIS Z0237. In the table, "None" indicates that there is no stopped ball.

(4) Shape Retention After Burning The test piece (length 100 mm, width 100 mm, thickness 3 m)
m) and a corn calorimeter (“CON
E2A "), and was irradiated (horizontally) with a heat of 50 kW / m ² for 30 minutes to burn. A metal plate (length 50 mm, width 50 mm, thickness 1 mm) is placed on a test piece (length 50 mm, width 50 mm) prepared by cutting the residue after burning.
Was placed on the metal plate, and weights of 10 g and 50 g were separately placed on the plate, and the residue was visually observed to see whether or not the residue collapsed (inset or cracked), and the shape retention was evaluated according to the following evaluation criteria. -Both 10 g and 50 g: those in which the residue did not collapse were evaluated as ◎-50 g in which the residue collapsed, but those in which the residue did not collapse in 10 g: ○-10 g in which the residue collapsed

In the evaluation of shape retention, "x" is very brittle, so that it is difficult to even cut out the test piece, and it collapses when the test piece is set up in the longitudinal direction.
In the case of vertical use in actual fire test or the like (for example, covering the back surface of the outer wall), it is expected that the resin will fall off and exhibit fire resistance performance in a short time.

[0077]

[Table 1]

The following components were used in the table. [Phosphorus compound]-Ammonium polyphosphate ("Sumisafe P" manufactured by Sumitomo Chemical Co., Ltd.)-t-butylphosphonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) [Graph made by thermal expansion] "CA-60S" manufactured by Nippon Kasei Co., Ltd. [Inorganic filler ]-Aluminum hydroxide ("B703" manufactured by Nippon Light Metal Co., Ltd.)
S ") ・ Magnesium hydroxide (" Kisuma 5B "manufactured by Kyowa Chemical Industry Co., Ltd.)

[0079]

The acrylic resin composition of the present invention uses a thermoplastic acrylic copolymer composed of a comb-shaped, star-shaped or block-shaped copolymer having a specific composition as a resin component, so that it has low weather resistance. In addition to being excellent, a resin composition having excellent moldability and adhesiveness can be obtained even when a large amount of an inorganic compound is contained, and an expanded heat insulating layer is formed upon heating, and further excellent fire resistance is obtained by maintaining its shape. It can be used for a wide range of applications such as building materials.

Claims (7)

[Claims] 1. A branched copolymer having a comb-shaped skeleton, a star-shaped copolymer
Branched copolymer having a skeleton, (ABA)_nMold blow
Block copolymer and (AB)_nType block copolymer
At least one thermoplastic acrylic copolymer selected from
100 parts by weight of coalesced, thermal expansion neutralized with phosphorus compound
20 to 200 parts by weight with the total amount of graphite, and inorganic
50-500 parts by weight of filler, neutralized heat
The weight ratio between the expandable graphite and the phosphorus compound is 9: 1 to 1: 1.
Acrylic resin composition characterized by being 00.
[Wherein A represents a vinyl polymer block, and B represents a general formula
CH_Two= CR¹COOR ^Two(Where R¹Is a hydrogen atom or
Represents a methyl group;^TwoRepresents an alkyl group having 2 to 14 carbon atoms
(Meth) acrylic acid ester represented by
(Shows a (co) polymer block as a position) 2. The acrylic resin composition according to claim 1, wherein the thermoplastic acrylic copolymer has tackiness at room temperature. 3. The thermoplastic acrylic copolymer has one or two glass transition temperatures (Tg), one of which has a peak temperature in the range of −70 to 20 ° C. Item 3. The acrylic resin composition according to Item 1 or 2. 4. The acrylic according to claim 1, wherein the weight ratio of the neutralized heat-expandable graphite: phosphorus compound is from 1: 3 to 1: 100. -Based resin composition. 5. The acrylic resin composition according to claim 1, wherein the phosphorus compound is ammonium polyphosphate. 6. The acrylic resin composition according to claim 1, wherein the inorganic filler is a hydrated inorganic substance. 7. The acrylic resin composition according to claim 1, wherein the inorganic filler is a metal salt and / or a metal oxide of a metal belonging to Group II or III of the periodic table.