JPH1143552A - Resin composition for foaming molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for foaming molding, capable of uniformly-finely foaming on the foaming molding and enabling to produce products excellent in surface appearance and mechanical strength. SOLUTION: This resin composition for foaming molding comprises 70-99.8 wt.% of methyl methacrylate monomer units and 0.2-30 wt.% of other monomer units capable of being copolymerized with the methyl methacrylate monomer units, has a weight-average mol.wt. of 50,000500,000 converted into polymethyl methacrylate and measured by gel permeation chromatography, and has a polymethyl methacrylateconverted Z-average mol.wt./polymethyl methacrylate- converted weight-average mol.wt. ratio of 1.8-70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel resin composition for foam molding. More specifically, weather resistance, heat resistance,
The present invention relates to a resin composition suitable for forming an acrylic resin foam having excellent mechanical strength. The resin composition of the present invention is capable of uniform foaming during foam molding, and can produce a foamed product excellent in mechanical strength and surface appearance. In addition, it is possible to recycle used foamed products by resolving them into raw monomers by pyrolyzing them, and extremely low generation of black smoke and soot when incinerated. . The foam obtained by molding the resin composition of the present invention can be widely used as a heat insulating material, a cushioning material, a building material used outdoors, a synthetic wood, a signboard, and the like.

[0002]

2. Description of the Related Art Conventionally, resin foam materials include polystyrene, impact-resistant polystyrene, AS resin, ABS, and the like.
Resins, polyvinylidene chloride, and the like have been used in applications and fields that make use of their respective characteristics. However, foams made of a resin containing styrene as a main component generally have poor weather resistance, and may cause yellowing when used in outdoor applications such as building materials, and the members and locations used are significantly restricted. There is a problem. In addition, when incinerated at the time of disposal, black smoke and soot are often generated, and therefore, it is not preferable from the viewpoint of environmental problems. These problems also apply to foams made of polyvinylidene chloride.

A so-called acrylic resin containing polymethyl methacrylate as a main component can be considered as a resin that solves the problems of polystyrene resin such as weather resistance and smoke generation during incineration. Molding of bodies, especially high foams, has been difficult. Although the reason for this is not completely clear, it is considered that the melt viscosity of the acrylic resin is generally high and the elasticity of the molten polymer is generally low. That is, if the molecular weight of the resin is reduced to lower the melt viscosity and improve the foamability and processability, the mechanical strength and solvent resistance of the foam are reduced.
On the other hand, when trying to lower the melt viscosity by raising the molding temperature without reducing the molecular weight, a gas mainly composed of methyl methacrylate is generated due to the thermal decomposition of the resin, and it is difficult to control the foaming. It becomes difficult to manufacture.
Further, the melt of the acrylic resin is inferior in elasticity and has a small ability to independently hold generated bubbles, so that it is difficult to foam sufficiently and uniformly, and it is difficult for the foam surface to be smooth. Therefore, the obtained foam was brittle and had an inferior appearance.

[0004] As a resin that compensates for the problems when such an acrylic resin is used as a foam, methyl methacrylate-
A proposal using a styrene copolymer (MS resin) has been made (JP-B-51-24307, JP-B-51-272).
No. 64), and use of a methyl methacrylate-styrene copolymer having a specific melt viscosity index and a weight average molecular weight has also been proposed (Japanese Patent Publication No. 58-3561).
No. 3, JP-B-7-122001).

However, in these proposals, styrene is used as a copolymer component, so that the weather resistance is still insufficient. In order to improve the impact resistance of the foam, a proposal has been made to incorporate a multi-layered impact modifier into the methyl methacrylate-styrene copolymer (Japanese Patent Publication No. 3-7696). However, it was still insufficient in terms of improving the uniformity of the foam and the fragility of the foam.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a resin composition suitable for molding an acrylic resin foam having excellent weather resistance, heat resistance, mechanical strength, surface appearance, and recyclability, and producing less smoke during incineration. They try to provide things. In particular, in order to produce a resin foam excellent in mechanical strength and surface appearance, the present invention is intended to respond to a request for a resin composition that enables uniform foaming during foam molding.

[0007]

In order to solve the above-mentioned problems, the present inventor has analyzed the melting behavior of the resin, and considered that it is necessary to increase the elasticity of the melt to realize fine and uniform foaming. , Earnestly studied. As a result, they have found that by using an acrylic resin composition having a specific copolymer composition and a molecular weight distribution, remarkable effects can be obtained on elasticity and ductility at the time of melting, and have completed the present invention.

That is, the present invention comprises 70 to 99.8% by weight of a methyl methacrylate monomer unit and 0.2 to 30% by weight of another monomer unit copolymerizable therewith, and is used for gel permeation chromatography. Weight average molecular weight in terms of polymethyl methacrylate measured using
The present invention relates to a foam molding resin composition having a ratio of Z-average molecular weight in terms of polymethyl methacrylate / weight-average molecular weight in terms of polymethyl methacrylate of 1.8 to 70.

Hereinafter, the present invention will be described in more detail. The resin composition of the present invention comprises 70 to 99.8% by weight of a methyl methacrylate monomer unit and 0.2 to 30% by weight of another monomer unit copolymerizable therewith. Other monomers copolymerizable with the methyl methacrylate monomer include alkyl methacrylate having an alkyl group having 2 to 18 carbon atoms, alkyl acrylate having an alkyl group having 1 to 18 carbon atoms, acrylic acid and methacrylic acid. Aromatic vinyls such as α, β-unsaturated acids such as acids, divalent carboxylic acids containing unsaturated groups such as maleic acid, fumaric acid and itaconic acid, and their alkyl esters, styrene, α-methylstyrene and nuclear-substituted styrene. Compounds, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, and the like. These may be independently copolymerized with a methyl methacrylate monomer, or two or more types. May be used in combination to copolymerize with a methyl methacrylate monomer. In addition, a copolymer of methyl methacrylate and methacrylic acid or acrylic acid is subjected to a heat treatment to remove alcohol or dehydrate to produce a 6-membered cyclic anhydride unit, and to form a copolymer with ammonia, amine and imide. A polymer that has undergone a chemical reaction to form a six-membered ring imide unit can also be included. Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoints of light resistance, heat decomposition resistance, and fluidity of the resin composition. Methyl acrylate, ethyl acrylate and n-butyl acrylate are particularly preferred. When the amount of the methyl methacrylate monomer unit is less than 70% by weight, the heat resistance and weather resistance of the obtained foam are reduced. On the other hand, when the amount is more than 99.8% by weight, the degradation of thermal decomposition due to depolymerization is reduced. Since it is remarkable, the foaming rate cannot be controlled due to generation of decomposition gas during foam molding, and it becomes difficult to perform uniform and fine foaming, which is not preferable. It is preferable that the monomer be composed of 80 to 99% by weight of a methyl methacrylate monomer unit and 1 to 20% by weight of an alkyl acrylate unit having 1 to 18 carbon atoms in an alkyl group.

[0010] In the resin composition of the present invention, its molecular weight and molecular weight distribution are important. When the weight average molecular weight in terms of polymethyl methacrylate and the Z average molecular weight in terms of polymethyl methacrylate measured using gel permeation chromatography are used as the indices, uniform fine foaming is achieved, and a foam having excellent mechanical strength and surface appearance is obtained. It has been found that the viscosity and elasticity at the time of melting can be controlled in order to obtain. Hereinafter, the weight average molecular weight in terms of polymethyl methacrylate and the Z average molecular weight in terms of polymethyl methacrylate are abbreviated as M _RW and M _RZ , respectively.

M _RW and M _RZ are obtained by performing the following measurements. That is, gel permeation chromatography (hereinafter abbreviated as GPC) using tetrahydrofuran as a solvent and so-called monodispersed polymethyl methacrylate having a narrow molecular weight distribution as a standard substance of a molecular weight.
Is measured, and a calibration curve between the molecular weight and the elution time is prepared. GPC measurement was performed using a solution of the sample polymer having a concentration of 1 mg / ml, and MPC was determined based on the following equations (1) and (2).
Calculate _RW and _MRZ .

[0012] _{M RW = (ΣM Ri W i} ) / ΣW i (1) M RZ = {(Σ (M Ri) 2 W i)} / (ΣM Ri W i) (2) ( wherein, the M _Ri W _i represents the i th fraction of polymethylmethacrylate equivalent molecular weight and polymer weight concentration respectively, sigma is. represents a summation over all fractions) Thus measuring the molecular weight by GPC, the polymer is branched structure In the case where it is included, it is generally said that a true molecular weight is not given, and the value is underestimated. However, in the present invention, it is an effective index from the viewpoint of controlling the viscosity and elasticity at the time of melting in order to achieve uniform fine foaming and obtain a foam having good mechanical strength and surface appearance.

[0013] The resin composition of the present invention is characterized in that the M _RW is 50,000 to 500,000, preferably 70,000 to 400,000, more preferably 90,000 to 350,000. If M _RW is less than 50,000,
Insufficient viscosity of the resin at the time of melting makes it difficult to achieve uniform and fine foaming in foam molding, which is not preferable because the resulting foam has poor appearance and mechanical strength. On the other hand, M
_{If the RW} exceeds 500,000, the viscosity of the resin at the time of melting becomes excessively high and the moldability is reduced. In particular, extrusion foaming becomes difficult, and if the molding temperature is increased to supplement the moldability, thermal decomposition of the resin may occur. In such a case, uniform foaming becomes difficult, and the appearance and mechanical strength of the obtained foam are inferior.

The resin composition of the present invention is characterized in that the ratio of M _RZ / M _RW is from 1.8 to 70, preferably from 2 to
60, more preferably 6 to 50. This M _RZ / M
The ratio of _RW represents the molecular weight distribution and is an index that can be particularly related to the behavior of the resin at the time of melting. M _RZ / M _RW
When the ratio is less than 1.8, the elasticity of the resin at the time of melting is insufficient, so that it is difficult to hold the bubbles at the time of foaming, and it is difficult to cause uniform fine foaming, which is not preferable. On the other hand, M _RZ
When the ratio of / M _RW exceeds 70, the elasticity of the resin at the time of melting becomes excessive, and it is difficult to carry out stable foaming, which is also not preferable. Thus, it was found that the relationship between the ratio of M _RZ / M _RW and the melting behavior of the resin at the time of foam molding was found.
It was important in completing the present invention.

The importance of elongational flow analysis has been recognized with respect to the flow of a polymer melt in a molding process such as film molding, blow molding and foam molding. As a parameter, especially of degree rapid increase of elongational viscosity, Ramudaexp viscosity at small deformation at low strain rates λl viscosity at (t = t _l), the time at a high strain rate t _l (large deformation) Then, the non-linear parameters defined by these ratios λexp / λl are noted (Koyama, Journal of the Rheology Society of Japan, Vol. 19, p. 174, 1991). The resin composition of the present invention at 170 ° C. in the extensional viscosity measurements, the viscosity of 200 seconds at a viscosity λl and strain rate 0.01 sec ^-1 of 200 seconds at a strain rate 0.003sec ^-1 λ
The nonlinear parameter λn defined by the ratio λexp / λl to exp is preferably 1.1 to 10, more preferably 1.5 to 9, and particularly preferably 2 to 8. When the nonlinear parameter λn is less than 1.1, the elasticity is insufficient when the molten resin is stretched, so-called necking easily occurs, it is difficult to foam uniformly and finely, and a foam excellent in appearance and mechanical strength is obtained. It is difficult to obtain, which is not preferable. On the other hand, if the nonlinear parameter λn is 1
If it exceeds 0, the elasticity when the molten resin is stretched becomes excessively large, and the resin is easily melted and uniform foaming becomes difficult.

The resin composition of the present invention has an orifice having an inner diameter of 2.1 mm attached to a melt flow rate measuring device.
The melt flow rate measured under the conditions of 30 ° C. and 3.8 kg load is preferably 0.2 g / 10 minutes or more. The die swell ratio of the strand of the molten resin is 1.
It is preferably at least 5, more preferably at least 1.8. Melt flow rate is 0.2g / 10
When the time is less than 1 minute, the melt viscosity of the resin composition is excessively large, and particularly, extrusion foaming becomes difficult, which is not preferable. In addition, the die swell ratio is an index related to the elasticity of the resin composition at the time of melting. If the ratio is less than 1.5, so-called necking is likely to occur due to insufficient elasticity of the resin at the time of melting, and uniform fine foaming is caused. Is difficult to do,
It is difficult to obtain a foam having excellent appearance and mechanical strength, which is not preferable.

The method for producing the resin composition of the present invention is not particularly limited, and any method may be used as long as a resin composition having a controlled molecular weight and molecular weight distribution can be obtained. For example, the following manufacturing method can be used. 1. A stage in which the polymerization reaction is performed in parallel using a plurality of reactors, and a resin composition in which the polymers produced in each reactor are uniformly mixed in a solution state or a molten state to control the molecular weight and the molecular weight distribution. Manufacturing method comprising the steps of: 2. The polymerization reaction is continuously performed using a plurality of serial reactors, and the molecular weight and molecular weight distribution of the final resin composition are controlled by controlling the molecular weight and molecular weight distribution of the polymer generated in each reactor. To control and manufacture. 3. A production method combining the above parallel and series reactors. 4. A method in which a polymer having a high molecular weight is dissolved in a monomer mixture in advance, and then a polymerization reaction is performed to control the molecular weight and molecular weight distribution of the resin composition to produce the resin composition. 5. During the polymerization of the monomer mixture, a chain transfer agent and / or
Alternatively, a method in which the molecular weight and the molecular weight distribution of a resin composition finally formed by post-adding a monomer are controlled to produce the resin composition. 6. A method for producing a resin composition in which a plurality of individually produced polymers having different molecular weights and molecular weight distributions are uniformly mixed in a solution state or a molten state to control the molecular weight and the molecular weight distribution.

The type of polymerization method includes suspension polymerization,
Any of known methods such as emulsion polymerization, bulk polymerization, and solution polymerization may be used, and these methods may be used alone or in combination of plural types. Examples of the combination of polymerization modes include, for example, the following methods. I. The monomer mixture is partially bulk-polymerized in the presence (or absence) of a very small amount of a chain transfer agent to produce a high molecular weight component, and then the partially polymerized product is suspended in water using a suspending aid. A method of obtaining a pearl-shaped resin composition in which the molecular weight and the molecular weight distribution are controlled by suspending and completing the polymerization. B. Emulsion polymerization of the monomer mixture in the absence of a chain transfer agent,
A monomer mixture is added to the high molecular weight component to form a mixture,
A method of obtaining a pearl-shaped resin composition in which the molecular weight and the molecular weight distribution are controlled by suspending in water using a suspending aid to complete the polymerization.

When a solvent is used during the polymerization reaction, it is important to select a chemically stable one so as not to impair the transparency, color tone and weather resistance of the resin composition to be produced. Examples of such a solvent include cyclohexane, cyclohexanone, butyl acetate, methyl isobutyrate, toluene, xylene, ethylbenzene and the like, and these can be used alone or in combination of two or more.

Further, the resin composition of the present invention may be a polymer having a branch in whole or in part. Also in this case, the production method is not particularly limited, and for example, the following methods can be used, and these methods can be carried out alone or in combination. a. A method for producing a graft polymer by copolymerizing a polymer or oligomer having a polymerizable functional group at one end (a so-called macromer or macromonomer) with a monomer copolymerizable therewith. b. A method for producing a graft polymer by generating a polymerization initiation point in a trunk polymer by a hydrogen abstraction reaction or the like and initiating polymerization of a monomer from the polymerization initiation point. c. A method for producing a branched polymer using a polyfunctional initiator having three or more functional groups capable of initiating a polymerization reaction in one molecule. d. A method for producing a polymer containing a branched polymer by using a polyfunctional chain transfer agent having three or more chain transferable functional groups in one molecule. e. A method for producing a branched polymer by performing a coupling reaction with a compound having three or more functional groups in one molecule capable of reacting with a polymer or oligomer having a functional group at one end.

In the case of these branched polymers,
For example, by manufacturing by controlling the molecular weight of the polymerizable oligomer or polymer, and by controlling the molecular weight when copolymerizing this with the monomer by a method such as the use of a chain transfer agent,
It is possible to produce a resin composition having a desired molecular weight and molecular weight distribution. As a practical method for controlling the molecular weight and molecular weight distribution, when a multifunctional monomer having two or more polymerizable functional groups in one molecule is copolymerized with a normal monofunctional monomer, Alternatively, a method of controlling the molecular weight distribution by adjusting the copolymerization rate of the polyfunctional monomer and the molecular weight of the resulting copolymer is also possible. This method is advantageous in that the molecular weight and molecular weight distribution can be controlled widely even with only one reactor, and a polymer can be produced in a uniform dispersion state.

Examples of the polyfunctional monomer include ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate,
1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate,
Polyethylene glycol diacrylate (2 to 20 ethylene oxide units in the molecule), polyethylene glycol dimethacrylate (2 to 20 ethylene oxide units in the molecule), 2,2′-bis (4-methacryloyloxyphenyl) propane, Allyl methacrylate,
Bifunctional monomers such as divinylbenzene, trifunctional monomers such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, glycerin tris acrylate, and glycerin tris methacrylate; Erythritol tetraacrylate, tetrafunctional monomers such as pentaerythritol tetramethacrylate, dipentaerythritol hexaacrylate, hexafunctional monomers such as dipentaerythritol hexamethacrylate, and the like. Alternatively, two or more types may be used in combination. The copolymerization rate of the polyfunctional monomer is generally determined by a relatively small amount of copolymerization because the resulting polymer must be soluble in a solvent during GPC measurement to prevent the formation of a three-dimensional crosslinked product. Can.

The resin composition of the present invention may contain two or more kinds of branched polymers, or may be a mixture of a branched polymer and a general unbranched polymer (linear polymer). Even with such a mixture, M _RW is 50,000 to 500,000 and M _RZ / M
It is important that the ratio of _RW is 1.8 to 70,
The molecular weight distribution can be set based on the measurement using Examples of the type of polymerization reaction for producing the resin composition of the present invention include known methods such as free radical polymerization, living radical polymerization, living anion polymerization, coordination anion polymerization, cationic polymerization, and group transfer polymerization (group transfer polymerization). And any of these may be used alone or in combination of a plurality of types.

When a free radical polymerization is used as a polymerization initiator for producing the resin composition of the present invention,
Di-t-butyl peroxide, dilauroyl peroxide, t-butylperoxy 2-ethylhexanoate, 1,1-bis (t-butylperoxy) 3,3
Use of a peroxide-based radical polymerization initiator such as 5-trimethylcyclohexane or an azo-based general radical polymerization initiator such as azobisisobutyronitrile, azobisisovaleronitrile, and 1,1-azobis (1-cyclohexanecarbonitrile). These may be used alone or in combination of two or more. These radical polymerization initiators are generally used in the range of 0.001 to 1% by weight based on the monomer mixture. Further, these radical polymerization initiators and a suitable reducing agent may be combined to be used as a redox initiator. In addition, the resin composition may be manufactured using an anionic polymerization method using an alkyl lithium or the like, a coordination polymerization method using an organometallic complex, a group transfer polymerization method, or the like.

The polymerization temperature for producing the resin composition of the present invention can be selected in an appropriate range according to the type of the polymerization reaction. 30-120 ° C for suspension polymerization or emulsion polymerization by radical polymerization, and 50-120 ° C for bulk or solution polymerization.
It is common to carry out at 180 ° C. In the continuous bulk or continuous solution polymerization by the radical polymerization method, the polymerization is generally carried out at a polymerization temperature of 100 ° C. or higher in order to stably discharge a mixture of a polymer, a monomer, and a solvent from a reactor.

In order to control the molecular weight of the resin composition of the present invention, a generally used chain transfer agent can be used when the resin composition is produced by a radical polymerization method. Examples of the chain transfer agent include n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, 2-ethylhexyl thioglycolate, ethylene glycol dithioglycolate, trimethylolpropane tris (thioglycolate), and pentaerythritol tetrakis (thio). Mercaptans such as (glycolate) are preferred from the viewpoint of heat decomposition resistance and weather resistance of the resin composition. Use Such chain transfer agents may be added to the mixture at a concentration required monomer mixture or the monomer and the polymer in order to control the range of from 5 to 500,000 and M _RW of the resin composition of the present invention Can. Generally, it is used in the range of 0.001 to 1% by weight based on the monomer mixture.

In order to produce the resin composition of the present invention, a resin in which a plurality of individually produced polymers having different molecular weights and molecular weight distributions are uniformly mixed in a solution state or a molten state to control the molecular weight and the molecular weight distribution. There is no particular limitation on the method of mixing the composition. There is a method of mixing with a drum blender or a Henschel mixer, a method of mixing with these methods and then granulating at a temperature of 200 to 280 ° C. using an extruder. In the case of extrusion mixing, it is preferable to pay attention to the extrusion temperature, the water content of the polymer, the nitrogen purge in the extruder, and the like in order to suppress discoloration and thermal decomposition of the resin composition.

In producing the resin composition of the present invention, dyes, pigments, organic light diffusing agents such as methyl methacrylate / styrene copolymer beads, sulfuric acid, etc. may be used as long as the effects of the present invention are not impaired. Inorganic light diffusing agents such as barium, titanium oxide, calcium carbonate, talc, etc., heat stabilizers such as hindered phenols and phosphates, antioxidants, benzotriazoles, 2-hydroxybenzophenones, phenyl salicylate UV absorbers, plasticizers such as phthalate esters, fatty acid esters, trimellitate esters, phosphate esters, polyesters, etc., higher fatty acids, higher fatty acid esters, mono-, di-, or triglycerides of higher fatty acids, etc. Release agents, higher fatty acid esters, lubricants such as polyolefins, polyethers, Antistatic agents such as ether ester type, polyether ester amide type, alkyl sulfonate, alkyl benzene sulfonate, flame retardant such as phosphorus type, phosphorus / chlorine type, phosphorus / bromine type, reinforcement of glass fiber, carbon fiber, etc. Agents and the like may be mixed and used. The method of blending these additives is not particularly limited, and can be carried out by a known method. For example, a method in which an additive is dissolved in a monomer mixture in advance and polymerized, or a method in which the additive is dry-blended with a mixer or the like in a molten state, beads, or pellets, and kneaded and granulated using an extruder. And the like.

The method for producing a foam using the resin composition of the present invention is not particularly limited, and it can be carried out by a known method such as physical foaming or chemical foaming. The apparatus can be manufactured by any method such as extrusion foam molding, injection foam molding, and bead foam molding. Particularly, it is suitable for use in processing into an irregular shape such as a plate shape or a rod shape by extrusion foam molding. When a foam is produced using the resin composition of the present invention, the resin temperature is set to 180 to 2 to prevent burning and deterioration of the resin.
It is preferable to carry out in the range of 70 ° C.

Examples of the foaming agent include saturated aliphatic hydrocarbons such as propane, butane and hexane, halogenated hydrocarbons such as trichlorotrifluoroethane, carbon dioxide and water. These can be used alone. Or two or more of them may be used in combination. A nucleating agent may be used during foam molding. Talc or silica powder is preferably used as the nucleating agent.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described more specifically with reference to Examples and Comparative Examples below, but the present invention is not limited thereto. The evaluation and test methods used are shown below. 1. Composition analysis of acrylic copolymerPolymer solution of polymer in dichloromethane
It was dried, decomposed at 445 ° C. in a nitrogen stream using a Curie Point Pyrolyzer JHP-3 manufactured by Shimadzu Corporation, and the monomer component produced by depolymerization was immediately introduced into a gas chromatography column for analysis. From this data, quantitative calculation was performed using the analysis result of a polymer having a known composition obtained by bulk polymerization as a standard. 2. Gel permeation chromatography (GP
C) Dissolve 20 mg of sample in 20 ml of tetrahydrofuran,
The measurement was carried out at a column temperature of 38 ° C. using tetrahydrofuran as a solvent using a TOSOH HLC-8020 type GPC measuring apparatus equipped with a TOSOH TSK-gel-SuperH type column. The same measurement was performed in advance using standard polymethyl methacrylate (manufactured by Waters) having a narrow molecular weight distribution, and a calibration curve between the elution time and the molecular weight was prepared. The average molecular weight was calculated from the chromatogram of each sample based on the following equations (1) and (2).

[0032] _{M RW = (ΣM Ri W i} ) / ΣW i (1) M RZ = {(Σ (M Ri) 2 W i)} / (ΣM Ri W i) (2) ( wherein, the M _Ri W _i each represent an i-th fraction of polymethylmethacrylate equivalent molecular weight and polymer concentration by weight, sigma represents a summation over all fractions.) 3. Melt flow rate (MFR) Measured under the conditions I of ASTM D1238. 4. Die swell ratio The diameter of the strand when the above-mentioned MFR measurement was performed was measured with a caliper, and the ratio was shown by dividing by the inner diameter of the MFR orifice 2.1 mm. 5. Nonlinear Parameters A strand having a diameter of 2 to 5 mm produced by melt-flowing from a melt flow rate measuring device was used as a sample, and a Toyo Seiki Merten Rheometer No. 1 was used. 170 ° C using 670
The elongational viscosity measurement was performed at Strain rate 0.003se
Viscosity λl after 200 seconds at c ^-1 and strain rate 0.01 sec
The viscosity λexp after 200 seconds was measured at ⁻¹ , and the ratio λexp /
λl was defined as a non-linear parameter. 6. Drop weight strength test A weight having a weight of 100 g was dropped from a height of 30 cm, and deformation and breakage of the foam were observed. 7. Evaluation of weather resistance The appearance and color change of the foam after exposure for 1000 hours with a sunshine weather ometer were visually judged.

Abbreviations indicate the following compounds. MA; methyl methacrylate MA; methyl acrylate BA; butyl acrylate ST; styrene EGDMA; ethylene glycol dimethacrylate LPO; lauroyl peroxide AIVN; azobisisovaleronitrile BPTMCH; 1,1-bis (t-butylperoxy)
-3,3,5-trimethylcyclohexane n-OM; n-octylmercaptan Parts are by weight unless otherwise specified.

[0034]

EXAMPLE 1 30 liters of ion-exchanged water, 150 g of tertiary calcium phosphate and 1.2 g of sodium lauryl sulfate were charged into a 60 liter stainless steel pressure-resistant reactor equipped with a stirrer, and stirred at 75 ° C. under a nitrogen atmosphere.
To a state where the effect of oxygen was virtually eliminated. MMA
16000 g, MA 4000 g, EGDMA 24 g, L
A monomer mixture consisting of 40 g of PO, 52 g of n-OM and 2 g of Tinuvin P (manufactured by Nippon Ciba Geigy) was added to the reactor, reacted at 75 ° C. for 3 hours, and then heated to 90 ° C. or higher and kept for another hour. The polymerization was completed. The resulting polymer was separated by filtration, washed with water, and dried to obtain a bead-shaped acrylic resin (A).

The result of composition analysis of this acrylic resin (A) was MMA unit / MA unit = 80/20 (weight ratio) (EGDMA could not be detected because it was a trace amount). The result of the GPC analysis was as follows: M _RW = 31
× 10 ⁴ and M _RZ / M _RW = 3.3. And M
The FR was 1.3 g / 10 minutes, and the die swell measured from the strand at this measurement was 1.9. Further, the nonlinearity parameter at 170 ° C. was 1.2.

Talc is mixed with the acrylic resin (A) as a foam nucleating agent by a Henschel mixer, and butane is pressed at a temperature of 240 ° C. while pressing butane as a foaming agent from an injection port using an extrusion foaming molding machine having a screw diameter of 30 mm. A low foam board having a size of about 2 cm, a width of about 15 cm, and a density of about 0.1 to 0.2 g / cm ³ was formed. The production results and evaluation results are shown in Tables 1 and 2.

[0037]

Comparative Example 1 A monomer mixture was prepared by using MMA (18800 g) and MA
An acrylic resin (B) was obtained in the same manner as in Example 1, except that the resin consisted of 1200 g, 40 g of LPO, 27 g of n-OM and 2 g of tinuvin P2. The composition analysis result of this acrylic resin (B) is MMA unit / MA unit = 9
4/6 (weight ratio), and the result of GPC analysis was M _RW = 14 × 10 ⁴ and M _RZ / M _RW = 1.6. The MFR was 0.5 g / 10 minutes, and the die swell measured from the strand at this measurement was 1.1. The nonlinearity parameter at 170 ° C. is 1.0
(I.e., not exhibiting non-linearity).

The following was evaluated in the same manner as in Example 1. Tables 3 and 4 show the production results and evaluation results.

[0039]

Example 2 Acrylic resin (A) produced in Example 1
Acrylic resin (B) produced in Comparative Example 1 with 60 parts by weight
40 parts by weight were mixed with a drum blender, and then melt-kneaded at 260 ° C. using an AS30 type twin-screw extruder manufactured by Nakatani Machine and pelletized. The composition analysis result of the obtained resin composition was as follows: MMA unit / MA unit = 85.5 / 14.5
(Eg, EGDMA could not be detected due to its trace amount). The result of the GPC analysis was M
_RW = 25 × 10 ⁴ and M _RZ / M _RW = 2.8.
Further, the MFR was 1.0 g / 10 minutes, and the die swell measured from the strand at this measurement was 1.5. The nonlinearity parameter at 170 ° C. was 1.1.

The following was evaluated in the same manner as in Example 1. Tables 1 and 2 show the production results and evaluation results.

[0041]

Example 3 16,000 g of MMA and MA
4000 g, EGDMA 10 g, LPO 40 g, n-O
M26g and Tinuvin P (Nippon Ciba Geigy) 2g
Acrylic resin (C) was obtained in the same manner as in Example 1, except that The composition analysis result of this acrylic resin (C) is obtained as follows: MMA unit / MA unit = 80/20
(Weight ratio) (EGDMA is not detected because it is very small),
The result of GPC analysis was M _RW = 34 × 10 ⁴ and M _RZ / M _RW = 2.7. MFR is 0.3g / 1
It was 0 minutes, and the die swell measured from the strand at the time of this measurement was 1.6. The nonlinearity parameter at 170 ° C. was 1.1.

The following was evaluated in the same manner as in Example 1. The production results and evaluation results are summarized in Tables 1 and 2.

[0043]

Example 4 90 parts by weight of MMA and 10 parts by weight of MA were placed in a completely mixed-type stainless steel pressure-resistant reactor having an internal volume of 10 liters.
And charged monomer mixture consisting AIVN0.02 parts continuously, 40 ° C., subjected to preliminary polymerization in the conditions of an average residence time of 2 hours, M _RW is approximately 1.5 million of the polymer to about 10
A syrup containing% by weight was prepared. Ethylbenzene 5 parts by weight, BPTMCH0.
While mixing 01 parts by weight and 0.20 parts by weight of n-OM, the mixture was continuously fed into a second completely mixed-type stainless steel pressure-resistant reactor having an internal volume of 10 liters under a condition of 150 ° C. and an average residence time of 2 hours. The polymerization was carried out and the conversion rate of the monomer was 59
By weight, a mixture containing 56% by weight of a solid component and containing unreacted monomers, solvent, initiator and chain transfer agent residues and decomposition residues was obtained. Next, this mixture was constantly dispensed with a gear pump, cast and dropped into a devolatilization tank,
After removing volatile components at a degree of vacuum of 30 Torr or less and a temperature of 220 ° C., tinuvin P0.01 was added per 100 parts by weight of the polymer.
The mixture was extruded while mixing parts by weight with a mixer and granulated to obtain an acrylic resin (D) as pellets.

The result of composition analysis of this acrylic resin (D) was MMA unit / MA unit = 90/10 (weight ratio), and the result of GPC analysis was that M _RW = 15 × 10 ⁴
And M _RZ / M _RW = 6.5. MFR is 1.0g
/ 10 minutes, and the die swell measured from the strand at the time of this measurement was 1.9. The nonlinearity parameter at 170 ° C. was 1.6.

The following was evaluated in the same manner as in Example 1. The production results and evaluation results are summarized in Tables 1 and 2.

[0046]

EXAMPLE 5 85.5 parts by weight of MMA, MA9.
5 parts by weight, ethylbenzene 5 parts by weight, BPTMCH0.
A monomer mixture consisting of 01 parts by weight and 0.01 part by weight of n-OM was continuously charged, and 150 ° C., average residence time 2
Polymerization was carried out under the conditions of time, the conversion of the monomer was 55% by weight,
A polymer having a solid content of 52% by weight, an unreacted monomer,
A mixture containing a solvent, a residue of the initiator and the chain transfer agent, and a decomposition residue was obtained. 85.5 parts by weight of MMA, 9.5 parts by weight of MA, 5 parts by weight of ethylbenzene, BP
A monomer mixture consisting of 0.01 part by weight of TMCH and 0.23 part by weight of n-OM was continuously charged, and polymerized under the conditions of 150 ° C. and an average residence time of 2 hours, and the conversion of the monomer was 55% by weight. A mixture containing a polymer having a solid content of 52% by weight, an unreacted monomer, a solvent, a residue of an initiator and a chain transfer agent, and a residue of decomposition were obtained. Each of these two mixtures was constantly dispensed with a gear pump, mixed in a 5/95 weight ratio using a static mixer, and then cast and dropped into a devolatilization tank.
After removing volatile matter at 0 ° C., 0.01 parts by weight of tinuvin P was mixed with 100 parts by weight of the polymer and extruded while being mixed with a mixer, and granulated to obtain an acrylic resin (E) as pellets.

The composition analysis result of this acrylic resin (E) was MMA unit / MA unit = 90/10 (weight ratio), and the result of GPC analysis was M _RW = 14 × 10 ⁴
And M _RZ / M _RW = 6.2. MFR is 1.1g
/ 10 minutes, and the die swell measured from the strand at the time of this measurement was 1.8. The nonlinearity parameter at 170 ° C. was 1.5.

The following was evaluated in the same manner as in Example 1. The production results and evaluation results are summarized in Tables 1 and 2.

[0049]

Comparative Example 2 A monomer composed of 93 parts by weight of MMA, 2 parts by weight of MA, 5 parts by weight of ethylbenzene, 0.01 parts by weight of BPTMCH and 0.28 parts by weight of n-OM was placed in a completely mixed stainless steel pressure-resistant reactor having an internal volume of 10 liters. The mixture was continuously charged and polymerized under the conditions of 150 ° C. and an average residence time of 2 hours. A polymer having a conversion of a monomer of 59% by weight and a solid component content of 56% by weight, an unreacted monomer, a solvent, A mixture containing a residue of initiator and chain transfer agent and a residue of decomposition was obtained. The mixture was constantly dispensed with a gear pump, and 0.03 parts by weight of tinuvin per 100 parts by weight of the polymer was extruded while mixing with a mixer, and the mixture was granulated to obtain an acrylic resin (F) as pellets.

Composition analysis result of this acrylic resin (F)
Is MMA unit / MA unit = 98/2 (weight ratio)
And the result of GPC analysis was M_RW= 7 × 10^FourYou
And M _RZ/ M_RW= 1.5. MFR is 6.2 g /
10 minutes, measured from the strand at the time of this measurement
Die swell was 1.1. Non-linear at 170 ° C
The shape parameter is 1.0 (that is, no non-linearity is exhibited).
Was).

The following was evaluated in the same manner as in Example 1. The production results and evaluation results are summarized in Tables 3 and 4.

[0052]

COMPARATIVE EXAMPLE 3 A monomer mixture was prepared using MMA (18,950 g) and MA
An acrylic resin (G) was obtained in the same manner as in Example 1, except that the resin was composed of 1050 g, 60 g of LPO, and 100 g of n-OM. The composition analysis result of this acrylic resin (G) was MMA unit / MA unit = 95/5 (weight ratio), and the result of GPC analysis was M _RW = 5 ×
10 ⁴ and M _RZ / M _RW = 1.5. MFR is 2
3 g / 10 minutes, and the die swell measured from the strand at the time of this measurement was 1.1. The nonlinearity parameter at 170 ° C. was 1.0 (that is, no nonlinearity was exhibited).

The following was evaluated in the same manner as in Example 1. The production results and evaluation results are summarized in Tables 3 and 4.

[0054]

EXAMPLE 6 30 liters of ion-exchanged water, 200 g of sodium dioctylsulfosuccinate, and 100 g of sodium formaldehyde sulfoxylate were charged into a stainless steel pressure-resistant reactor having an inner volume of 60 liters with a stirrer, and heated to 75 ° C. under a nitrogen atmosphere while stirring. It was warmed to virtually no effect of oxygen. MMA 18000g, BA20
00 g, dicumyl peroxide 20 g, n-OM 4 g
And 2 g of Tinuvin P are continuously added to the reactor over a period of 30 minutes, and reacted at 75 ° C. for 2 hours. Thereafter, the temperature is raised to 90 ° C. or higher and maintained for 1 hour to complete the polymerization. I let it. Observation of the produced latex with an electron microscope showed a substantially uniform particle size distribution with an average particle size of about 0.1 μm. This latex is salted out using an aqueous solution of sodium sulfate, filtered, washed with water, dried, and dried in powder form.
An acrylic resin (H) having a _RW of about 2.4 million was obtained.

Acrylic resin (F) produced in Comparative Example 2
97 parts by weight and 3 parts by weight of the acrylic resin (H) produced this time were mixed by a drum blender, and then melt-kneaded at 250 ° C. and pelletized using an AS30 twin screw extruder manufactured by Nakatani Machinery. The composition analysis result of the obtained resin composition was as follows: MMA unit / MA unit / BA unit = 94.0 / 5.
7 / 0.3 (weight ratio). The results of the GPC analysis were as follows: M _RW = 12 × 10 ⁴ and M _RZ / M _RW = 1
0.1. Furthermore, the melt flow rate is 4.9 g
/ 10 minutes, and the die swell measured from the strand at the time of this measurement was 1.9. The non-linearity parameter at 170 ° C. was 1.8.

The following was evaluated in the same manner as in Example 1. The production results and evaluation results are summarized in Tables 1 and 2.

[0057]

Examples 7 to 10 The same procedures as in Example 6 were carried out except that the type and amount of the acrylic resin used were changed as shown in Table 1. The production results and evaluation results are summarized in Tables 1 and 2.

[0058]

Comparative Examples 4 to 6 The same procedures as in Example 6 were carried out except that the type and amount of the acrylic resin used were changed as shown in Table 3.
The production results and evaluation results are summarized in Tables 3 and 4.

[0059]

Comparative Example 7 30 liters of ion-exchanged water, 200 g of sodium dioctylsulfosuccinate, and 100 g of sodium formaldehyde sulfoxylate were charged into a stainless steel pressure-resistant reactor with a stirrer having an inner volume of 60 liters, and heated to 75 ° C. under a nitrogen atmosphere while stirring. It was warmed to virtually no effect of oxygen. MMA 1880g, BA120
g, 2 g of dicumyl peroxide, 2 g of allyl methacrylate and 0.2 g of tinuvin P are continuously added to the reactor over a period of 30 minutes and reacted at 75 ° C. for another 30 minutes to form an innermost hard layer. Was completed. Next, a monomer mixture consisting of 8000 g of BA, 2000 g of ST, 200 g of allyl methacrylate and 1 g of tinuvin P was continuously added to the reactor over 2 hours.
The reaction was further carried out at 5 ° C. for 2 hours to complete the polymerization of the crosslinked soft layer. Then, MMA7500g, BA500g, n-
A monomer mixture consisting of 18 g of OM and 0.8 g of Tinuvin P was continuously added to the reactor over a period of 30 minutes.
The reaction was further performed at 60 ° C. for 60 minutes to complete the polymerization of the outermost hard layer. When the produced latex is observed with an electron microscope,
A substantially uniform particle size distribution with an average particle size of about 0.1 μm was shown. This latex was salted out using an aqueous sodium sulfate solution, filtered, washed with water, and dried to obtain a powdery acrylic resin (I) which is an acrylic rubber having a three-layer structure.

Acrylic resin (F) produced in Comparative Example 2
60 parts by weight and 40 parts by weight of the acrylic resin (I) produced this time were mixed by a drum blender, and then melt-kneaded at 250 ° C. and pelletized using an AS30 twin screw extruder manufactured by Nakatanani Machinery. The following was evaluated in the same manner as in Example 1.
The production results and evaluation results are summarized in Tables 3 and 4.

[0061]

Comparative Example 8 The resin used was Asahi Kasei's polystyrene “68”.
The operation was performed in the same manner as in Example 1 except that “0” was set. The production results and evaluation results are summarized in Tables 3 and 4.

[0062]

Comparative Example 9 The resin used was Asahi Kasei's polystyrene "G9".
401 ", except that" 401 "was used.
The production results and evaluation results are summarized in Tables 3 and 4.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

[0067]

The resin composition of the present invention has weather resistance, appearance,
A so-called high foam having a density of 0.014 to 0.074 g / cm ³ , which is excellent in mechanical strength, recyclability, and low smoke generation during incineration, is a so-called low foam having a density of 0.075 to 0.93 g / cm ^3. Can also be used for any of the manufacturing. A high-foamed body is suitable as a heat insulating material or a cushioning material by utilizing its strength. The low-foamed material can be widely used for building materials, synthetic wood, soundproof walls, signboards, and the like used outdoors because it can take advantage of weather resistance and mechanical strength, and can also perform processing such as nailing and saw cutting.

Claims (3)

[Claims] 1. Methyl methacrylate monomer unit 70 to
99.8% by weight and 0.2 to 30% by weight of other monomer units copolymerizable therewith, having a weight average molecular weight in terms of polymethyl methacrylate of 5 to 50 as measured by gel permeation chromatography. And the ratio of Z-average molecular weight in terms of polymethyl methacrylate / weight-average molecular weight in terms of polymethyl methacrylate is 1.8 to 70.
A resin composition for foam molding. 2. A measurement of extensional viscosity at 170 ° C., in a ratio λexp / λl the viscosity Ramudaexp of 200 seconds at a strain rate viscosity of 200 seconds at 0.003sec ^-1 λl and strain rate 0.01 sec ^-1 2. The method according to claim 1, wherein the defined nonlinear parameter .lambda.n is 1.1 to 10.
Item 7. The resin composition for foam molding according to item 1. 3. The resin composition for foam molding according to claim 1, wherein the ratio of Z-average molecular weight in terms of polymethyl methacrylate / weight-average molecular weight in terms of polymethyl methacrylate is 6 to 50.