JP2676538B2 - Manufacturing method of molded products with improved resistance to oxidative deterioration - Google Patents

Description

TECHNICAL FIELD The present invention relates to a molded article obtained by ring-opening polymerization of a norbornene-based monomer in a mold in the presence of a metathesis catalyst system,
More specifically, it relates to a method for producing a polynorbornene-based molded product having improved resistance to oxidation deterioration.

Conventional technology Reaction injection molding of norbornene-based monomers represented by dicyclopentadiene (hereinafter abbreviated as DCP) (hereinafter RI
A ring-opening polymer (polynorbornene-based molded product) excellent in mechanical strength, heat resistance, water resistance and the like can be obtained by ring-opening polymerization in a mold by a method such as M).

However, since the polynorbornene-based molded product retains some unsaturated bonds, the surface of the molded product is susceptible to oxidative deterioration, and as a result, a hard and brittle film is formed on the surface layer. This film is inferior in impact resistance, and in particular, the DuPont impact strength value due to a falling weight decreases significantly with time. For example, the DuPont impact strength value of a polynorbornene-based molded product immediately after ring-opening polymerization is as high as 400 kgf · cm or more, but it is 80
Approximately 30 kgf due to oxidative deterioration after 72 hours treatment test at ℃
・ It drops sharply to about cm.

As described above, the molded product obtained by ring-opening polymerization of the norbornene-based monomer is susceptible to oxidative deterioration from the surface layer over time, impact resistance is lowered, and cracks are likely to occur.

In order to improve the oxidation deterioration resistance of polynorbornene-based molded products, conventionally, the molded products are coated with various paints, a thermoplastic resin sheet is laminated on the molded product surface, or an antioxidant is added to the norbornene-based monomer. A method of adding and molding (Japanese Patent Laid-Open No. 58-129013) has been proposed.

However, the coating method generally forms a hard coating film, and thus the impact resistance of the surface of the molded product is relatively low. In addition, in the method of forming a composite by laminating thermoplastic resin sheets, many thermoplastic resins have poor adhesion to polynorbornene-based molded products, and the molded products generally have a soft surface and have a somewhat hard surface. Is unsuitable for applications where is required. With the method of adding an antioxidant,
The antioxidant is almost uniformly dispersed in the molded product and cannot be distributed in a high concentration on the surface portion, so that the effect of preventing oxidative deterioration of the surface layer is insufficient. Therefore, when a large amount of an antioxidant is added, the glass transition point (Tg) of the molded article is lowered or the mechanical strength is lowered due to its plasticizing effect.

An object of the present invention is to provide a molded product having improved oxidation deterioration resistance while maintaining excellent physical properties of the polynorbornene-based molded product such as heat resistance and mechanical strength. is there.

Further, it is an object of the present invention to provide a molded product which prevents oxidative deterioration from the surface of a polynorbornene-based molded product and has excellent impact resistance.

Therefore, as a result of intensive studies to solve the problems of the prior art, the present inventors found that if an antioxidant and / or ultraviolet absorber-containing layer is formed on the surface of a polynorbornene-based molded product, The present invention has been completed based on the finding that the above can be achieved.

Means for Solving the Problem That is, the gist of the present invention is as follows.

(1) A molded article formed of a ring-opening polymer of a norbornene-based monomer is immersed in a solution in which an antioxidant and / or an ultraviolet absorber is dissolved in an organic solvent capable of swelling the polymer. A method of manufacturing a molded article with improved resistance to oxidative deterioration.

(2) A solution in which an antioxidant and / or an ultraviolet absorber is dissolved in an organic solvent capable of swelling a ring-opening polymer of norbornene-based monomer is applied on the inner surface of the mold in advance, and then the norbornene-based monomer is opened in the mold. A method for producing a molded article having improved resistance to oxidative deterioration, which is characterized by ring polymerization.

Thus, according to the present invention, there is provided a method for producing a molded article in which a layer containing an antioxidant and / or an ultraviolet absorber is formed on the surface of a molded article obtained by ring-opening polymerization of a norbornene-based monomer in a mold. It

 Hereinafter, the constituent features of the present invention will be described in detail.

(Norbornene-based Monomer) The norbornene-based monomer used as a raw material of the ring-opening polymer (molded product) of the present invention is a bicyclic or tricyclic or higher polycyclic norbornene-based monomer. When it is a tricyclic compound or more, a polymer having a high heat distortion temperature can be obtained and the heat resistance required as a composite material can be satisfied.

Further, in the present invention, the polymer to be produced can be a thermosetting type, and for that purpose, at least 10% by weight, preferably 30% by weight or more of the crosslinkable monomer in all monomers may be used.

Examples of the bicyclic norbornene-based monomer include 2-norbornene, 5-methyl-2-norbornene, 5-ethylidene-2-norbornene, and 5-phenylnorbornene.

Examples of tricyclic or higher norbornene monomers include tricyclics such as dicyclopentadiene and dihydrodicyclopentadiene, tetracyclics such as tetracyclododecene, pentacyclics such as tricyclopentadiene, and tetracyclopentadiene. Heptacyclics such as these, and their alkyl-substituted forms (eg, methyl, ethyl, propyl,
Butyl-substituted products), alkylidene-substituted products (eg, ethylidene-substituted products), aryl-substituted products (eg, phenyl, tolyl, naphthyl-substituted products) and the like.

Among them, tricyclic or pentacyclic is awarded from the viewpoints of availability, reactivity, heat resistance and the like.

The crosslinkable monomer is a polycyclic norbornene-based monomer having two or more reactive double bonds, and specific examples thereof include dicyclopentadiene, tricyclopentadiene, and tetracyclopentadiene. Therefore, when the norbornene-based monomer and the crosslinkable monomer are the same, it is not necessary to use any other crosslinkable monomer.

These norbornene-based monomers may be used alone or in combination of two or more.

The tricyclic or higher norbornene-based monomer can also be obtained by heat-treating disillopentadiene. The conditions of the heat treatment include a method of heating dicyclopentadiene in an inert gas atmosphere, preferably with an antioxidant added, and heating at a temperature of 120 to 250 ° C. for 0.5 to 20 hours. By this heat treatment, a monomer mixture containing pentacyclopentadecadiene (that is, cyclopentadiene trimer) and unreacted dicyclopentadiene is obtained.

The tricyclic or higher norbornene-based monomer 1
Monocyclic cycloolefins such as cyclobutene, cyclopentene, cyclopentadiene, cyclooctene, and cyclododecene, which can undergo ring-opening polymerization with one or more species, can be used in combination within the range not impairing the object of the present invention.

The catalyst to be used may be any metathesis catalyst known as a catalyst for ring-opening polymerization of norbornene monomers (for example, JP-A-58-127728, JP-A-58-129013,
59-51911, 60-79035, 60-186511, 61
-126115), but there is no particular limitation.

Examples of metathesis catalysts include tungsten, molybdenum, tantalum and other halides, oxyhalides, oxides, organic ammonium salts, and the like.
Further, specific examples of the activator (cocatalyst) include an alkyl aluminum halide, an alkoxyalkyl aluminum halide, an aryloxyalkyl aluminum halide, and an organic tin compound.

The metathesis catalyst is contained in 1 mol of the norbornene-based monomer, and is usually about 0.01-50 mmol, preferably 0.1-1.
Used in the range of 0 mmol. The activator (cocatalyst)
It is preferably used in a range of 2 to 10 (molar ratio) with respect to the catalyst component.

It is preferable that both the metathesis catalyst and the activator are dissolved in a monomer before use. However, the metathesis catalyst and the activator may be suspended or dissolved in a small amount of a solvent as long as the properties of the product are not substantially impaired.

(Molded Product) The molded product used in the present invention is a ring-opening polymer (polynorbornene-based molded product) obtained by ring-opening polymerization of a norbornene-based monomer in a bulk form. Substantially bulk polymerization is sufficient, and a small amount of an inert solvent may be present.

In a preferred method for producing a ring-opening polymer, a norbornene-based monomer is divided into two liquids and placed in another container, a metathesis catalyst is added to one and an activator is added to the other, and two stable reaction solutions (reactions Prepare a stock solution). The two kinds of reaction solutions are mixed and then poured into a mold or a mold having a predetermined shape (both are collectively referred to as a mold), where ring-opening polymerization is performed in bulk.

In the present invention, an impact mixing device conventionally known as a RIM molding device can be used for mixing two kinds of reaction solutions. In this case, the containers containing the two reaction solutions serve as separate flow sources. Two types of flow
The mixing head of the RIM machine is used for instantaneous mixing and then poured into a hot mold, where the bulk polymerization takes place immediately.

If the pot life at room temperature is as long as 1 hour, after mixing the two reaction volumes in the mixer, inject or pour into the preheated mold once or several times. (For example, JP-A-59-5191)
No. 1, U.S. Pat. No. 4,426,502). This method has the advantages that the size of the apparatus can be reduced and that the apparatus can be operated at a low pressure, as compared with the collision mixing apparatus.

Further, the present invention is not limited to the case where two kinds of reaction solutions are used. As can be easily understood by those skilled in the art, various modifications are possible, such as, for example, putting a reaction solution and an additive in a third container and using it as a third stream.

Mold temperature is usually 30 ℃ or more, preferably 40 ~ 200
C., particularly preferably 50 to 130.degree. Mold pressure is normal
It is in the range of 0.1 to 100 kg / cm ² .

The polymerization time may be appropriately selected, but is usually shorter than about 20 minutes, preferably 5 minutes or less, but may be longer.

The components used in the polymerization reaction are preferably stored and manipulated under an inert gas atmosphere such as nitrogen gas. The molding die may be sealed with an inert gas, but need not be.

Optional components Modifying the characteristics of the molded article of the present invention by blending various additives such as an antioxidant, a filler, a reinforcing material, a foaming agent, a pigment, a colorant, an elastomer, and a dicyclopentadiene-based thermopolymerization resin. can do.

The additives are mixed in advance with either one or both of the reaction stock solutions, or placed in the cavity of the mold.

Fillers include inorganic fillers such as glass, carbon black, talc, calcium carbonate, and mica. As the reinforcing material, there is a fibrous filler such as glass fiber or carbon fiber.

As the elastomer, natural rubber, polybutadiene (BR), polyisoprene, styrene-butadiene copolymer (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS) , EPDM, ethylene vinyl acetate copolymer (EVA) and their hydrides.

(Antioxidant, UV Absorber) Examples of the antioxidant that can be used in the present invention include various antioxidants for plastics and rubbers such as phenol-based, phosphorus-based, and amine-based. Further, in the present invention, an ultraviolet absorber which is usually used as a light stabilizer for plastics and rubber can also be used. These antioxidants and ultraviolet absorbers may be used alone or in combination of two or more.

Examples of phenolic antioxidants include 4,4-dioxydiphenyl, hydroquinone monobenzyl ether, 2,4-dimethyl-6-t-butylphenol, and 2,6-
Di-t-butylphenol, 2,6-di-amylhydroquinone, 2,6-di-t-butyl-p-cresol, 4-hydroxymethyl-2,6-di-t-butylphenol, 4,
4'-methylene-bis- (6-t-butyl-o-cresol), 4,4'-methylene-bis- (2,6-di-t-butylphenol), 1,3,5-trimethyl-2, 4,6-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, octadecyl-3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate], butylated hydroxyanisole, phenol condensate, butylated phenol, dialkylphenol sulfide, high molecular weight polyphenol, bisphenol and the like.

Examples of phosphorus-based antioxidants include aryl or alkylaryl phosphites such as tri (phenyl) phosphite, tris (noniphenyl) phosphite and tris (2,4-di-t-butylphenyl) phosphite. Can be mentioned.

Examples of amine-based antioxidants include phenyl-
α-naphthylamine, phenyl-β-naphthylamine, 4,4′-dioctylphenylamine, N, N′-di-β
-Naphthyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N-phenyl-N'-
Cyclohexyl-p-phenylenediamine, N, N'-di-o-tolyl-ethylenediamine, alkylated diphenylamine and the like can be mentioned.

As these antioxidants, various commercial products other than those mentioned above can be used.

Examples of the ultraviolet absorber include 4-t-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, ethyl-2-cyano-3,3-diphenyl. Acrylate, 2-ethylhexyl-2-cyano-3,3-
Diphenyl acrylate, phenyl salicylate, 2,2 '
-Dihydroxy-4,4'-dimethoxybenzophenone,
2,2 ', 4,4'-tetrahydroxybenzophenone, 2
(2'-hydroxy-5'-methylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-t
-Butylphenyl) benzotriazole, bis (2,2,6,
6-tetramethyl-4-piperidine) sebacate, 4
[(N-Ethyl-N-phenylamino) methylenamino]
Examples thereof include benzoic acid ethyl ether.

(Method of Forming Antioxidant and / or Ultraviolet Absorber-Containing Layer) As a specific method of forming the antioxidant and / or ultraviolet absorbent-containing layer on the surface of the polynorbornene-based molded article, ring-opening polymerization is carried out. There is a method of immersing the resulting molded article in an organic solvent solution of an antioxidant and / or an ultraviolet absorber, and a method of previously applying and drying the organic solvent solution on the inner surface of the mold.

Immersion Treatment Method An antioxidant and / or an ultraviolet absorber is dissolved in an organic solvent that easily swells a polynorbornene-based molded article such as toluene, and the molded article is dipped in the solution to form an antioxidant and / or an antioxidant in the surface layer. When penetrating the UV absorber,
After the solvent is dried and removed, a thick layer of the antioxidant and / or the ultraviolet absorber is formed on the surface of the molded product.

Examples of the organic solvent include tetrahydrofuran, diethyl ether, benzene, toluene, xylene, ethyl acetate, pyridine, cyclohexane, hexane, heptane, oxazoline, dimethylformamide, ligroin, chloroform, gasoline, trichloroethylene, carbon tetrachloride and the like. You can

The concentration of the antioxidant and / or the ultraviolet absorber in the organic solvent solution is not particularly limited, but from the viewpoint of the efficiency of the immersion treatment, it is preferably 1 to 60% by weight, more preferably 3 to 50% by weight, and further preferably Is 5 to 30% by weight.

The immersion temperature is in the range of room temperature (23 ° C.) to the boiling point of the organic solvent, and usually the temperature is around room temperature. The immersion time depends on the concentration of the antioxidant and / or the ultraviolet absorber, but it is 1 minute to 5 hours, preferably 3 to 30 minutes.

After the immersion treatment, the molded product is dried to remove the organic solvent. The drying method includes air drying and hot air drying.

Method of applying to the inner surface of the mold When the norbornene-based monomer is subjected to ring-opening polymerization in the presence of the metathesis catalyst system in the mold, if the organic solvent solution is applied to the inner surface of the mold in advance by spraying or brush coating, After the completion of the ring-opening polymerization reaction, a thick layer of the antioxidant and / or the ultraviolet absorber is formed on the surface layer of the polynorbornene-based molded article.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Parts and percentages are by weight unless otherwise specified.

Example 1 (immersion treatment method) Dicyclopentadiene (DCP) was placed in two containers,
On the other hand, for DCP, diethyl aluminum chloride (DEA
C) was added at a concentration of 33 mmol, n-propanol was added at a concentration of 42.9 mmol, and silicon tetrachloride was added at a concentration of 20 mmol. On the other hand, tri (tridecyl) ammonium molybdate was added to DCP to a concentration of 4 mmol.

After both reactions were mixed at a ratio of 1: 1 and poured into a mold (300 x 300 x 3 mm) heated to 80 ° C and the ring-opening polymerization reaction was performed for about 3 minutes to produce a poly DCP plate-shaped molded product. Obtained. These series of operations were performed in a nitrogen gas atmosphere.

Each sample of this plate-shaped molded product was treated by the following immersion treatment method.

10% by weight of various antioxidants and ultraviolet absorbers of toluene were prepared, and each molded product sample was immersed for 20 minutes. Then, it was air dried at room temperature for 24 hours.

A DuPont impact test was performed on each of the obtained molded product samples after the treatment, and the initial value before the oxidation treatment was measured. Then, each molded product sample in the air atmosphere,
After performing the oxidation treatment at 80 ° C. for 72 hours, the DuPont impact test was performed again, and the value after the deterioration test was measured.

The antioxidants and ultraviolet absorbers used are as follows.

(A) 2,6-di-t-butyl-p-cresol (BHT; manufactured by Sumitomo Chemical Co., Ltd.) (B) 4,4'-methylene-bis (2,6-di-t-butylphenol) (Ethanox 702; Ethyl Corp. USA) (C) 1,3,5-Trimethyl-2,4,6-tris (3,5-di-
t-Butyl-4-hydroxybenzyl) benzene (Ethanox 330; manufactured by Ethyl Corp. USA) (D) tris (nonylphenyl) phosphite (Mark 1178; manufactured by Adeka Argus) (E) phenyl-β-naphthylamine ( Noclizer D; manufactured by Ouchi Shinko Co., Ltd. (F) 4 [(N-ethyl-N-phenylamino) methylenamino] benzoic acid ethyl ester (Givsorb UV2; manufactured by GIVAUDAN Co.) DuPont impact strength According to the method, after the impact test that impacts one side of the 300 × 300 mm surface of the molded product (300 × 300 × 3 mm), on the surface opposite to the impact surface of the molded product (the surface where the convex shape is formed by the impact) The impact strength value was defined as the value that did not cause cracks to be caught by the nail.

 The measurement results are collectively shown in Table 1.

As is clear from Table 1, the molded article obtained by the method of the present invention has a DuPont impact strength value of 400 kgf · cm or more even when subjected to an oxidation treatment at 80 ° C. for 72 hours in an air atmosphere. Some of them have retained and show a high degree of resistance to oxidative deterioration. On the other hand, the impact strength of the untreated molded article was extremely reduced to 30 kgf · cm after the oxidation treatment.

Example 2 (mold inner surface coating method) 2,6-di-t-butyl-p-cresol (B
HT; manufactured by Sumitomo Chemical Co., Ltd.) was added so as to be 5%, and 5 ml per one surface was sprayed on both inner surfaces of a mold (300 × 300 × 3 mm) heated to 80 ° C.

After leaving it for 1 minute, casting was performed under the same conditions as in Example 1. When a DuPont impact test was performed on the obtained molded product sample, the DuPont impact value before oxidation was 40.
It was 0 kgf · cm or more. Then, the molded product sample at 80 ℃
When the DuPont impact test was performed again after the oxidation treatment was performed for 72 hours, the value after deterioration was 320 kgf · cm.

EFFECTS OF THE INVENTION The method of the present invention can provide a molded product with improved oxidation deterioration resistance while maintaining the excellent physical properties of the polynorbornene-based molded product such as heat resistance and mechanical strength.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gento Yamato 1-2-1 Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa Nippon Zeon Co., Ltd. Research and Development Center (56) References JP-A-62-1731 (JP, A) )

Claims (2)

(57) [Claims] 1. A molded article formed of a ring-opening polymer of a norbornene-based monomer is immersed in a solution in which an antioxidant and / or an ultraviolet absorber is dissolved in an organic solvent capable of swelling the ring-opening polymer. A method for producing a molded article having improved oxidation deterioration resistance, which is characterized by the following. 2. A solution in which an antioxidant and / or an ultraviolet absorber is dissolved in an organic solvent capable of swelling a ring-opening polymer of a norbornene-based monomer is applied on the inner surface of the mold in advance, and then the norbornene-based monomer is applied in the mold. A method for producing a molded article having improved resistance to oxidative deterioration, which comprises subjecting ring-opening polymerization to.