JP2002332306A - Resin composition, molded product and method for manufacturing molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a methacrylic material having excellent heat resistance without causing cracks in the surface even in the service environment at >=200 deg.C. SOLUTION: A resin composition comprises (A) 30-60 pts.wt. monomeric mixture containing a monofunctional unsaturated monomer having methyl methacrylate as the major component and a polyfunctional unsaturated monomer having at least two radically polymerizable double bonds in the molecule, (B) 40-70 pts.wt. particles of a resin which is composed of a polymer of an unsaturated monomer having methyl methacrylate as the major component and has been partially crosslinked, (C) a radical polymerization initiator, and (D) a hindered phenolic compound having at least one tertiary butyl group in the ortho-position of the phenolic hydroxyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition, a molded article, and a method for producing a molded article. More specifically, the present invention relates to a molded article having excellent heat resistance and a method for producing the same, and to a resin composition used for obtaining the molded article.

[0002]

2. Description of the Related Art A methacrylic resin containing methyl methacrylate as a main component is excellent in transparency, surface gloss, weather resistance, mechanical properties, and the like.
It is widely used for various purposes such as signboards and building materials.

However, when a methacrylic resin is used in a place where the temperature is relatively high, such as a meter cover of an automobile or a lamp cover of a lighting fixture, a problem often arises that heat resistance is insufficient and deformation occurs.

As a method of imparting heat resistance, there is a method of adding a polyfunctional unsaturated monomer having at least two radically polymerizable double bonds in one molecule when polymerizing a methacrylic resin.

As a resin composition further improved by applying this method, the present inventor has previously described a monofunctional unsaturated monomer containing methyl methacrylate as a main component and a double bond capable of radical polymerization in one molecule. A polymer mixture of an unsaturated monomer having methyl methacrylate as a main component and partially crosslinked resin particles and radical polymerization initiation in a monomer mixture comprising a polyfunctional unsaturated monomer having at least two It has been proposed to add an agent (JP-A-2000-226406). This resin composition is excellent in moldability,
By molding this, it is possible to obtain a molded article having high heat resistance.

[0006]

Problems to be Solved by the Invention
The resin composition described in Japanese Patent No. 406 has high heat resistance as compared with a general methacrylic material and can withstand use at a temperature of about 180 ° C., but when used at a higher temperature, It was then clarified that some had crack-like defects on the surface.

The present inventors have studied a methacrylic material which is excellent in heat resistance and does not crack on the surface even in a use environment of 200 ° C. or more, and has completed the present invention.

[0008]

That is, the present invention provides a resin composition containing the following components (A) to (D). (A) A monomer mixture containing a monofunctional unsaturated monomer having methyl methacrylate as a main component and a polyfunctional unsaturated monomer having at least two radical polymerizable double bonds in one molecule. 30 to 60 parts by weight, (B) resin particles 40 to 60% by weight of a polymer of unsaturated monomer mainly composed of methyl methacrylate, including particles composed of partially crosslinked resin
70 parts by weight, (C) a radical polymerization initiator, and (D) a hindered phenol compound having at least one tertiary butyl group at the ortho-position of the phenolic hydroxyl group.

[0009] The present invention also provides a molded article obtained by curing the resin composition.

[0010] The present invention further relates to the above components (A) to
It is an object of the present invention to provide a method for producing a molded article in which (D) is mixed and aged to form a molding material, and the molding material is shaped and cured.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Component (A) of the resin composition of the present invention comprises a monofunctional unsaturated monomer having methyl methacrylate as a main component and a polyfunctional unsaturated monomer having at least two radically polymerizable double bonds in one molecule. It is a monomer mixture containing a monomer. The monofunctional unsaturated monomer having methyl methacrylate as a main component means methyl methacrylate alone or a mixture of methyl methacrylate and a monofunctional unsaturated monomer copolymerizable therewith, and the amount of methyl methacrylate Is at least 50% by weight, preferably at least 70% by weight, more preferably at least 90% by weight. In addition, monofunctional unsaturated monomers copolymerizable with methyl methacrylate,
For example, methyl acrylate, ethyl acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl acrylate, benzyl (meth) ) Esters of methacrylic acid or acrylic acid such as acrylate and cyclohexyl acrylate with aliphatic, aromatic and alicyclic alcohols; hydroxyethyl (meth) acrylate, hydroxypropyl (meth)
(Meth) acrylic monomers such as hydroxyalkyl esters such as acrylate and hydroxybutyl (meth) acrylate; unsaturated acids such as acrylic acid and methacrylic acid; styrene based monomers such as styrene and α-methylstyrene Acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, vinyl acetate and the like. These can be used alone or in combination of two or more.

The monomer mixture of component (A) comprises 1
Examples of the polyfunctional unsaturated monomer having at least two radical polymerizable double bonds in the molecule include allyl methacrylate, ethylene glycol di (meth) acrylate,
Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol Di (meth) acrylate, neopentyl glycol di (meth) acrylate, divinylbenzene, diallyl phthalate, trimethylolpropane tri (meth)
Acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, and the like. These can be used alone or in combination of two or more.

The monofunctional unsaturated monomer and the polyfunctional unsaturated monomer are in an amount ratio of 20 to 90% by weight for the former and 1 for the latter.
The content is preferably set to 0 to 80% by weight. If the amount of the polyfunctional unsaturated monomer is less than 10% by weight, a molded article having sufficient heat resistance cannot be obtained. On the other hand, when the amount of the polyfunctional unsaturated monomer is more than 80% by weight, the impact strength of the obtained molded article decreases.

The component (B) of the resin composition of the present invention is resin particles comprising a polymer of an unsaturated monomer mainly composed of methyl methacrylate. The polymer of an unsaturated monomer mainly composed of methyl methacrylate is a polymer of a methacrylic resin composition containing 50% by weight or more of methyl methacrylate, and is methyl methacrylate or a monomer copolymerizable therewith with methyl methacrylate. It is obtained by polymerizing a mixture containing a functional unsaturated monomer. The amount of methyl methacrylate in the methacrylic resin composition is usually at least 50% by weight, preferably at least 70% by weight, more preferably at least 90% by weight. As the monofunctional unsaturated monomer copolymerizable with methyl methacrylate, those shown above can be applied.

Some or all of the resin particles made of the polymer are partially crosslinked. Of the resin particles, the ratio of such crosslinked resin particles is usually 20
１００100% by weight. The ratio of crosslinked resin particles is 2
If the amount is less than 0% by weight, the obtained molding material tends to adhere, and the handleability is reduced. Crosslinked resin particles, for example,
When polymerizing an unsaturated monomer mainly composed of methyl methacrylate by a method such as emulsion polymerization, suspension polymerization or dispersion polymerization, the polyfunctional unsaturated monomer shown above is referred to as an unsaturated monomer. Usually 0.1% based on the total amount with the polyfunctional unsaturated monomer.
It can be obtained by adding from 0.05 to 10% by weight. As another method for producing the crosslinked resin particles, for example, there is a method of pulverizing a polymer obtained by bulk polymerization. The remainder of the resin particles is a polymer of an unsaturated monomer mainly composed of methyl methacrylate, but is not crosslinked, and its proportion is 0 to 80% by weight. Uncrosslinked resin particles can be obtained by the same operation as in the method for producing crosslinked resin particles except that the polyfunctional unsaturated monomer is not added.

The resin particles have a particle diameter of 1 μm or more and 100 μm or more.
Those having a size of not more than μm are preferred. When resin particles having a particle diameter smaller than 1 μm are used, it becomes difficult to mix the component (A) with the monomer mixture. Conversely, when resin particles having a particle diameter exceeding 100 μm are used, irregularities due to the resin particles may appear on the surface of a molded product obtained by shaping and curing the resin composition.

The resin particles include an antioxidant, an ultraviolet absorber,
It may contain a chain transfer agent, a release agent, a dye, a pigment, or an inorganic filler.

When the total ratio of component (A) and component (B) is 100 parts by weight, the former is 30 to 60 parts by weight, and the latter is 30 to 60 parts by weight. Is 40-7
It is preferably in the range of 0 parts by weight. If the amount of the component (B) is too large and the amount of the component (A) is too small, the moldability of the obtained molding material is reduced. In addition, shrinkage during shaping and curing becomes large, and it becomes difficult to obtain a molded body having a smooth surface.
On the other hand, if the amount of the component (B) decreases and the amount of the component (A) increases too much, it tends to adhere, and in extreme cases, the shape is difficult to maintain during molding.

The component (C) of the resin composition of the present invention is a radical polymerization initiator. The radical polymerization initiator may be any as long as it can initiate the polymerization of the monomer mixture of the component (A). For example, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2 '-Azobis (2,4,4-trimethylpentane), 2,2'-
Azobis (2-methylpropane), 2-cyano-2-propyrazoformamide, dimethyl 2,2′-azobis (2-methylpropionate), 2,2′-azobis (2-methyl-butyronitrile), 2, 2′-azobisisobutyronitrile, 2,2′-azobis [2- (2-
Azo compounds such as imidazolin-2-yl) propane; diacyl and dialkyl peroxides such as dicumyl peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide, benzoyl peroxide and lauroyl peroxide Compounds: t-butylperoxy-3,3,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisobutyrate, t-butylperoxyacetate, di-t-butylperoxy Hexahydroterephthalate, di-t-butylperoxyazelate, t-butylperoxy-2-ethylhexanoate, 1,1,
Peroxyester compounds such as 3,3-tetramethylbutylperoxy-2-ethylhexanoate and t-amylperoxy-2-ethylhexanoate; t-
Percarbonate compounds such as butylperoxyallyl carbonate and t-butylperoxyisopropyl carbonate; 1,1-di-t-butylperoxycyclohexane, 1,1-di-t-butylperoxy-3,
3,5-trimethylcyclohexane, 1,1-di-t-
And peroxyketal compounds such as hexylperoxy-3,3,5-trimethylcyclohexane.
These radical polymerization initiators can be used alone or in combination of two or more.

The amount of the polymerization initiator depends on the components (A) and (B)
Is preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight in total. If the amount of the polymerization initiator is less than 0.1 part by weight, it takes a long time to complete the radical polymerization. On the other hand, when the amount exceeds 5 parts by weight, the polymerization stability decreases.

Component (D) of the resin composition of the present invention is a hindered phenol compound. The hindered phenol compound has at least one tertiary butyl group at the ortho-position of the phenolic hydroxyl group.
For example, 2,6-di-t-butyl-p-cresol,
2,6-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol, t-butylhydroxyanisole, n-octadecyl-3- (3 ′, 5′-di-t
-Butyl-4'-hydroxyphenyl) propionate, 2,2'-methylenebis- (4-methyl-6-t-
Butylphenol), 4,4'-butylidenebis- (3
-Methyl-6-t-butylphenol), 4,4'-thiobis- (3-methyl-6-t-butylphenol),
Tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5-t- Butylphenyl) butane, tris (3,5
-Di-tert-butyl-4-hydroxybenzyl) isocyanurate, 2-tert-butyl-6- (3-tert-butyl-2)
-Hydroxy-5-methylbenzyl) -4-methylphenyl acrylate and 3,9-bis [2- [3- (3
-T-butyl-4-hydroxy-5-methylphenyl)
Propionyloxy] -1,1-dimethylethyl] 2
4,8,10-tetraoxaspiro [5.5] undecane and the like. Among them, application of tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate is preferred.

The amount of the hindered phenol compound is 0.0 to 100 parts by weight of the total of the components (A) and (B).
It is preferably at least 1 part by weight. If the amount of this compound is less than 0.01 part by weight, it becomes difficult to obtain a molded article having sufficient heat resistance. As the amount of the hindered phenolic compound increases, the heat resistance of the obtained molded body improves. However, if the amount is too large, an effect commensurate with the amount cannot be obtained, so the amount is preferably 1 part by weight or less.

The resin composition of the present invention may contain an antioxidant such as an amine antioxidant, a sulfur antioxidant, and a phosphorus antioxidant within a range not to impair the effects of the present invention. Good. As the antioxidant at this time, a known antioxidant can be used, and the amount thereof is, based on the total amount of the antioxidant and the hindered phenol compound, based on 100 parts by weight of the total of the components (A) and (B). Preferably it does not exceed 1 part by weight. Further, the resin composition of the present invention, apart from additives contained in the resin particles such as an antioxidant, an ultraviolet absorber, a chain transfer agent, a release agent, a dye, a pigment, and an inorganic filler, a release agent Agents, ultraviolet absorbers, dyes, pigments, polymerization inhibitors, chain transfer agents, flame retardants or reinforcing agents, and the like.

Next, a molded article obtained by using this resin composition will be described. The molded article can be obtained by a method of curing the resin composition containing the components (A) to (D).
It is obtained by being cured by heating to 0 to 200 ° C.

For the production of a molded article, a method of mixing and aging the above-mentioned components (A) to (D) to obtain a molding material, and then applying and curing the molding material is applied. Can also. The mixing can be performed, for example, by putting the components (A), (B), (C) and (D) into a container provided with a stirring mechanism and stirring.

For aging, for example, a slurry-like mixture obtained by mixing is poured into a vessel provided with a heating mechanism, and
It can be performed by maintaining the temperature at 0 ° C to 100 ° C. When the temperature at the time of aging exceeds 100 ° C., the polymerization and curing reaction of the monomer mixture as the component (A) starts, which is not preferable. On the other hand, if the temperature is lower than 20 ° C,
Aging takes a long time. By the aging operation, the component (A) permeates into the crosslinked resin particles among the resin particles of the component (B). The appearance of the mixture after aging is clay-like or powder-like. At this time, non-crosslinked resin particles of the resin particles of the component (B) dissolve in the component (A). The shape of the container used for aging is not particularly limited, and examples thereof include a cell, a bag, and the like composed of at least two flat plates and a sealing material that seals the periphery. Any material that does not dissolve or erode in the mixture may be used.

Mixing and aging may be carried out using two different containers as described above. However, from the viewpoint of improving work efficiency, a predetermined device is used while stirring using a device provided with a stirring mechanism and a heating mechanism. , And mixing and aging can be performed by one apparatus. Examples of such a device include a twin-screw extruder, a universal mixer, a kneader, and a kneading device such as a Banbury mixer.

The shaping is performed by charging the molding material obtained by aging into molding dies of various shapes. The method used at this time includes, for example, compression molding, injection molding, transfer molding and the like.

The curing may be carried out under the usual conditions of a radical polymerization reaction, for example, by heating to a temperature in the range of 80 to 200 ° C. When the temperature is lower than 80 ° C., it takes a long time to complete the curing. On the other hand, if the temperature is too high, decomposition or coloring may occur.

[0030]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the evaluation method of a molding material and a molded object is as follows. (1) Handleability of molding material: The presence or absence of adhesion when wearing and touching polyethylene gloves was examined. (2) Formability of molding material: 38 g of molding material is put into a groove of a mold having a groove of 250 mm in length × 40 mm in width and 30 mm in depth, and a temperature of 120 ° C. and a mold clamping pressure of 80 kg / cm ^2. The plate was heated under pressure for 3 minutes to produce a plate-shaped molded product having a thickness of 3 mm, which was evaluated from the appearance of the obtained molded product. Although a molded article without cracks was obtained, the moldability was evaluated as good. (3) Transparency of molded article: The molded article produced in the above (2) was measured for total light transmittance and haze by a haze meter according to JIS-K7105, and yellowness (YI) was measured by a color difference meter. The higher the total light transmittance, the smaller the haze, and the smaller the YI, the better the transparency. (3) Heat resistance of the molded article: After keeping the molded article used in the above (3) in an oven heated to 200 ° C. for 8 hours, the appearance was inspected to determine whether or not cracking occurred. Further, the haze and YI of the molded body after heating are measured, and the increase in haze (Δhaze) and the increase in YI (ΔYI) of the molded body before and after heating are determined. From the magnitude of these increases, The heat resistance of the molded body was evaluated. The smaller the ΔHaze and ΔYI, the better the heat resistance.

Example 1 In a 500 ml polycup, 14 parts by weight of methyl methacrylate, 36 parts by weight of ethylene glycol dimethacrylate (trade name "NK Ester 1G", manufactured by Shin-Nakamura Chemical Co., Ltd.), 99.8% by weight of methyl methacrylate, and ethylene glycol dimethacrylate 50 parts by weight of crosslinked resin particles having a particle diameter of 4 μm and 0.29 parts by weight of t-amyl peroxy-2-ethylhexanoate obtained by suspension polymerization of a monomer mixture consisting of 0.2% by weight. And 2,6-di-t-butyl-4-methylphenol (trade name “Sumilyzer BH
T ", manufactured by Sumitomo Chemical Co., Ltd.)
The mixture was mixed to obtain a slurry resin composition.

The resin composition was poured into a polyethylene bag, sealed, and aged at 50 ° C. for 1 hour in a hot air drying oven. After cooling to room temperature, the powdery molding material was removed from the bag. For this molding material, handleability and moldability were evaluated. Further, the molded product obtained using this molding material was evaluated for transparency and heat resistance. Table 1 shows the results.

Examples 2 to 4 The same operation as in Example 1 was carried out except that Compound B, C or D shown in Table 1 was used instead of 2,6-di-tert-butyl-4-methylphenol. . Table 1 shows the results.

[0034]

[Table 1] * 1 Compound A: 2,6-di-t-butyl-4-methylphenol (trade name “Smilaiser BHT”, manufactured by Sumitomo Chemical Co., Ltd.) * 2 Compound B: tetrakis- [methylene-3- (3 ′, 5 ′) -Sh-t-butyl-4 '
-Hydroxyphenyl) fluoropionate] methane (trade name “Sumiraiser BP-10”
1 ", manufactured by Sumitomo Chemical Co., Ltd.) * 3 Compound C: n-octatedecyl-3- (3 ', 5'-di-t-butyl-4'-humandioxyphenyl) fluoropionate (trade name" Sumiraiser-BP-76 ", Sumitomo) * 4 Compound D: Tris (3,5-di-t-butyl-4-hydroxypropyl) isocyanurate (trade name "G3114", Goodrich)

Comparative Examples 1 and 2 The same procedure was performed as in Example 1 except that Compound E or F shown in Table 2 was used instead of 2,6-di-tert-butyl-4-methylphenol. Table 2 shows the results.

[0036]

[Table 2] * 5 Compound E: 2- [1- (2-human peroxy-3,5-di-t-pentylphenyl) ethyl] 4,6-di-t-pentylphenyl acrylate (trade name “Smilizer G”
S ", manufactured by Sumitomo Chemical Co., Ltd.) * 6 Compound F: pentaerythrityltetrakis (3-laurylthiophenofluorothionate)
(Product name "Sumiraiser TP-D", manufactured by Sumitomo Chemical Co., Ltd.)

The molded articles of Examples 1 to 4 not only have a sufficient total light transmittance, a small haze, and excellent transparency, but also have a crack on the surface even when heated to 200 ° C. No heat was generated and the heat resistance was excellent. Among them, the molded article of Example 4 has Δhaze, ΔY
I was small, and the heat resistance was very excellent.

[0038]

The resin composition of the present invention is useful as a material for obtaining a molded article having excellent transparency and heat resistance.
Further, according to the method for producing a molded article of the present invention, such a molded article can be easily obtained. The molded body obtained in this manner is used for automobile-related parts such as tail lamp covers and headlamp covers, resin tableware, water-related parts such as microwave oven windows, or various mechanical covers, various lenses, and solar energy-using water heater covers. And solar cell protection covers.

Claims (5)

[Claims] 1. A resin composition comprising the following components (A) to (D). (A) A monomer mixture containing a monofunctional unsaturated monomer having methyl methacrylate as a main component and a polyfunctional unsaturated monomer having at least two radical polymerizable double bonds in one molecule. 30 to 60 parts by weight, (B) a polymer of an unsaturated monomer having methyl methacrylate as a main component,
Resin particles containing particles of partially cross-linked resin
0 to 70 parts by weight, (C) a radical polymerization initiator, and (D) a hindered phenol compound having at least one tertiary butyl group at the ortho-position of the phenolic hydroxyl group. 2. The method according to claim 1, wherein the hindered phenol compound is 2,6.
-Di-t-butyl-p-cresol, 2,6-di-t-
Butylphenol, 2,4-dimethyl-6-t-butylphenol, t-butylhydroxyanisole, n-octadecyl-3- (3 ', 5'-di-t-butyl-4'-
(Hydroxyphenyl) propionate, 2,2′-methylenebis- (4-methyl-6-t-butylphenol), 4,4′-butylidenebis- (3-methyl-6
t-butylphenol), 4,4'-thiobis- (3-
Methyl-6-t-butylphenol), tetrakis-
[Methylene-3- (3 ', 5'-di-t-butyl-4'-
Hydroxyphenyl) propionate] methane, 1,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane, tris (3,5-di-t-
Butyl-4-hydroxybenzyl) isocyanurate,
2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate and 3,9-bis [2- [3- (3-t-butyl- 4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] 2,4,8,1
The resin composition according to claim 1, which is selected from 0-tetraoxaspiro [5.5] undecane. 3. The hindered phenol compound is tris (3,5-di-tert-butyl-4-hydroxybenzyl).
The resin composition according to claim 1, which is an isocyanurate. 4. A molded article obtained by curing the resin composition according to claim 1. 5. After mixing and aging the components (A) to (D) according to claim 1 to form a molding material, the molding material is molded,
A method for producing a molded article that cures.