JPH0234647A - Styrene polymer molding and its production - Google Patents

Abstract

PURPOSE:To obtain the title molding improved in heat resistance and soldering resistance by molding a styrene polymer mainly having a syndiotactic structure and irradiating the obtained molding with electron beams. CONSTITUTION:A styrene polymer mainy having a syndiotactic structure and preferably having a dyad content >=75% and a pentad content >=30% as determined on the basis of an analysis by the nuclear magnetic resonance of a carbon isotope, for example, a poly(alkyl)-styrene, a poly(halostyrene), a poly(alkoxystyrene), a poly(vinyl benzoate), a mixture thereof or a copolymer based thereon, is molded and irradiated with electron beams.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a styrenic polymer molded article and a method for producing the same, and more specifically, the present invention relates to a styrenic polymer molded article and a method for producing the same. This invention relates to a styrenic polymer molded article obtained by irradiation and an effective method for producing the same.

[Prior art and problems to be solved by the invention] In general, many resins are used in the manufacture of electrical and electronic parts, but in the case of connectors, for example, resins are often soldered to connect lead wires, etc. There are many. Therefore, in the manufacture of such electrical and electronic parts, general soldering is carried out at a temperature (2
60° C. or higher), a resin is required that has heat resistance to the extent that it can maintain the shape of the molded product (hereinafter, this property is referred to as "solder resistance"). Polyimide, polyphenylene sulfide, and the like are known as resins having such heat resistance, but these resins are expensive and pose a problem in terms of price.

On the other hand, polyethylene terephthalate (PET) is relatively inexpensive, but does not have sufficient heat resistance and cannot withstand soldering work.

The reality is that resins that have excellent solder resistance and are inexpensive and suitable for manufacturing electrical and electronic parts have not yet been obtained.

In addition, plastic bottles used as soft drink containers, which have been increasingly used in recent years, are manufactured by stretching PET, but it is difficult to use these plastic bottles at temperatures above the glass transition temperature (Tg) of PET. It is. Therefore, there has been a strong desire to develop a resin with excellent heat resistance suitable for manufacturing food containers such as heat-resistant plastic beverage bottles.

Under these circumstances, the group of the present inventors recently
We developed a styrenic polymer whose main chain mainly has a syndiotactic structure (Japanese Unexamined Patent Publication No. 104818/1983). Among these styrene polymers, a styrene homopolymer has a Tg of 100°C and a melting point of 100°C. (T m ) is 260
~270°C and is relatively inexpensive,
It was expected that it would be used in electrical and electronic components such as food containers that require the above-mentioned performance.

Therefore, the group of the present inventors proposed a molded product made of a crystalline material by molding the above styrene polymer and subjecting it to heat treatment (Japanese Patent Application No. 63-3846).
However, subsequent research has shown that although this molded product is significantly superior to conventional products, it does not have sufficient solder resistance, so it is not necessarily satisfactory for electrical and electronic parts that require heat resistance. It turned out that it wasn't possible. Furthermore, we also proposed a molded product obtained by stretch-blowing the above styrene polymer (Japanese Patent Application No. 63-384
However, molded products that are not heat-treated cannot withstand the use of hot water at around 100°C, and when heat-treated, problems such as deterioration of transparency and shrinkage occur, and eventually In this case, it was also difficult to obtain a molded product suitable for use as a food container, etc.

[Means to solve the problem]

As a result of intensive research to solve the above-mentioned problems, the present inventors have found that by irradiating a molded product obtained by molding a styrene polymer mainly having a syndiotactic structure with an electron beam, the objective can be achieved. It has been found that solder resistance, hot water resistance, etc. are significantly improved. The present invention was completed based on this knowledge.

That is, the present invention provides a styrenic polymer molded article obtained by irradiating an electron beam to a molded article mainly made of a styrenic polymer having a syndiotactic structure, and
Provided is a method for producing a styrenic polymer molded article, which comprises molding a styrenic polymer mainly having a syndiotactic structure, and then irradiating the obtained molded article with an electron beam. A styrenic polymer having a structure is melted at a temperature above the melting point and then rapidly cooled to create an amorphous raw sheet, and then the sheet is stretched at a temperature above the glass transition temperature and below the melting point to obtain a stretched film. The present invention also provides a method for producing a styrenic polymer molded article, which comprises irradiating it with an electron beam.

In the present invention, the styrenic polymer used as the material for the molded product mainly has a syndiotactic structure. Here, the term "mainly syndiotactic structure" means that the stereochemical structure is mainly a syndiotactic structure,
In other words, it has a three-dimensional structure in which phenyl groups and substituted phenyl groups, which are side chains, are located alternately in opposite directions with respect to the main chain formed from carbon-carbon bonds, and its toughness is determined by the carbon isotope. It is quantified by nuclear magnetic resonance method (C-NMR method). Toughness measured by C-NMR method is determined by the proportion of consecutive constituent units, e.g. , 3 can be represented by triat, and 5 can be represented by pentad, but the styrenic polymer mainly having a syndiotactic structure as referred to in the present invention is usually 75% or more diad, preferably 85 % or more, or 30% or more for pentads (racemic pentads), preferably 50% or more
Polystyrene, poly(alkyl styrene), poly(halogenated styrene), poly(alkoxystyrene), poly(vinyl benzoic acid ester), and mixtures thereof, having a syndiotacticity of % or more; Refers to polymers. Here, poly(alkylstyrene) includes poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tertiary-butylstyrene), etc., and poly(halogenated styrene) includes poly(halogenated styrene). (chlorostyrene), poly(bromostyrene), poly(fluorostyrene), etc. In addition, as poly(alkoxystyrene), poly(methoxystyrene), poly(
ethoxystyrene), etc. Among these, particularly preferred styrenic polymers include polystyrene, poly(
p-methylstyrene), poly(m-methylstyrene) 1
Poly(p-tert-butylstyrene).

Examples include poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), and copolymers of styrene and p-methylstyrene (JP-A-62-187708). Public bulletin).

Furthermore, the molecular weight of the styrenic polymer used in the present invention is not limited, but those having a weight average molecular weight of 10,000 or more are preferred, and those of 50,000 or more are particularly optimal. Further, there is no restriction on the width or narrowness of the molecular weight distribution, and various types can be used. This styrenic polymer mainly having a syndiotactic structure has a melting point of 160 to 310°C, and has much better heat resistance than conventional styrenic polymers having an atactic structure.

Such styrenic polymers, which mainly have a syndiotactic structure, can be prepared by using a styrenic polymer, for example, in an inert hydrocarbon solvent or in the absence of a solvent, using a titanium compound and a condensation product of water and trialkylaluminum as catalysts. It can be produced by polymerizing monomers (monomers corresponding to the above-mentioned styrenic polymers).

The molded article of the present invention is obtained by molding the above styrenic polymer, and the styrenic polymer contains commonly used thermoplastic resins, rubber, inorganic fillers, antioxidants,
Nucleating agent, plasticizer, compatibilizer.

Colorants, antistatic agents, etc. can be added.

Further, a crosslinking agent or a crosslinking aid may be added to promote the electron beam irradiation effect.

There are various antioxidants, but especially monophosphites and diphosphites such as tris(2,4-di-L-butylphenyl) phosphite and tris(mono- and di-nonylphenyl) phosphite. Phosphorous antioxidants and phenolic antioxidants are preferred. The diphosphite is represented by the general formula [wherein R' and R'' each represent an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms]. As a specific example of the phosphorus compound represented by the above-mentioned formula, it is preferable to use a phosphorus compound represented by the above-mentioned formula: distearyl pentaerythritol diphosphite;
Dioctylpentaerythritol diphosphite; diphenylpentaerythritol diphosphite; bis(2
, 4-dibutylphenyl)pentaerythritol diphosphite; bis(26-dibutylphenyl)pentaerythritol diphosphite;
Examples include dicyclohexylpentaerythritol diphosphite.

In addition, known phenolic antioxidants can be used, and specific examples include 2.6-di-L-butyl-4-methylphenol; 2.6-diphenyl-4-methoxyphenol; 2.2°-methylenebis(6-L-butyl-4methylphenol); 2,2°-
Methylenebis-(6-L-butyl-4-methylphenol); 2°2°-methylenebis[4-methyl-6-(α
-methylcyclohexyl)phenol); 1.1-bis(5-L-butyl-4-hydroxy-2-methylphenyl)butane, 2.2'-methylenebis(4-methyl-6
-cyclohexylphenol); 2.2'-methylenebis-(4-methyl-6-)nylphenol): 1,1
．． 3-tris-(5-mo-butyl-4-hydroxy-2
-methylphenyl)butane; 2,2-bis-(5-mo-
butyl-4-hydroxy-2-methylphenyl) -4
-n-dodecylmercaptobutane; ethylene glycol-bis[3,3-bis(3-t-butyl-4-hydroxyphenyl)butyrate); 1-1-bis(3,5-dimethyl-2-hydroxyphenyl)- 3-(n-dodecylthio)-butane; 4.4°-thiobis(6-t-butyl-3-methylphenol); 1,3.5-)lis(3
,5-di-L-butyl-4-hydroxybenzyl)-2
,4,6-drimethylbenzene;2,2-bis(3,5
-di-t-butyl-4-hydroxybenzyl) malonic acid dioctadecyl ester; n-octadecyl-3-(4
-hydroxy-3,5-di-t-butylphenyl)propionate; tetrakis[methylene(3,5-di-t-
butyl-4-hydroxyhydrocinnamate)]methane, and the like.

The above antioxidant is based on 100 parts by weight of the styrenic polymer mainly having a syndiotactic structure.
It is blended in a proportion of 0.0001 to 2 parts by weight, preferably 0.001 to 1 part by weight.

If the blending ratio of the antioxidant is less than 0.0001 parts by weight, the molecular weight will drop significantly, while if it exceeds 2 parts by weight, the mechanical strength will be affected, so both are not preferred.

Examples of thermoplastic resins include styrene polymers such as atactic polystyrene, isotactic polystyrene, AS resin, and ABS resin, polyesters such as polyethylene terephthalate,
Polycarbonate.

Polyethers such as polyphenylene oxide, polysulfone, polyethersulfone, polyamides, polyphenylene sulfide (pps), condensation polymers such as polyoxymethylene, acrylic polymers such as polyacrylic acid, polyacrylic acid ester, polymethyl methacrylate, Polyethylene, polypropylene, polybutene, poly4-methylpentene-1, ethylene-propylene tf
Polyolefins such as Z-combined or polyvinyl chloride.

Examples include halogen-containing vinyl compound polymers such as polyvinylidene chloride and polyvinylidene fluoride.

Various rubbers can be used, but the most suitable rubber is a rubbery copolymer containing a styrene compound as one of its components.For example, the butadiene moiety of a styrene-butadiene block copolymer is partially or fully hydrogenated rubber (SEBS), styrene-butadiene copolymer rubber (SBR), methyl acrylate-butadiene-styrene copolymer rubber, acrylonitrile-butadiene-styrene copolymer rubber (ABS rubber), Acrylonitrile-alkyl acrylate-butadiene-styrene copolymer rubber (AABS), methyl methacrylate-alkyl acrylate-styrene copolymer rubber (MAS),
Examples include methyl methacrylate-alkyl acrylate-butadiene-styrene copolymer rubber (MABS). Rubber-like copolymers containing these styrene compounds as one component have styrene units, so they have good dispersibility in styrene polymers that mainly have a syndiotactic structure, and as a result, they have the effect of improving physical properties. is remarkable.

Other examples of rubbers that can also be used include natural rubber, polybutadiene, and polyisoprene.

Polyisobutylene, neoprene, ethylene-propylene copolymer rubber, polysulfide rubber, thiocol rubber,
Examples include acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, polyether/ester rubber, and polyester/ester rubber.

Furthermore, the inorganic filler may be fibrous, granular, or powdery. Glass fiber and carbon fiber are used as fibrous inorganic fillers.

Examples include alumina fiber. On the other hand, talc and carbon black are used as granular and powdery inorganic fillers.

Graphite titanium dioxide, silica, mica.

Calcium carbonate, calcium sulfate, barium carbonate.

Magnesium carbonate, magnesium sulfate, barium sulfate,
Oxysulfate tin oxide, alumina.

Examples include kaolin, silicon carbide, metal powder, and the like.

Further, as a crosslinking agent, L-butyl hydroperoxide;
Hydroperoxides such as cumene hydroperoxide; diisopropylhensenperoxide; 2,5-dimethyl-2,5-dihydroperoxyhexane; 2,5-dimethyl-2,5-dihydroperoxyhexane-3; dialkyl peroxides; Appropriate amounts of ketone peroxides, diacyl peroxides, peroxy esters, etc. can be used.

As a crosslinking aid, p-quinonedioxime; p.

Quinone dioximes such as p-dibenzoylquinone dioxime, methacrylates such as polyethylene glycol dimethacrylate, allyl compounds, maleimide compounds, and the like can be used as appropriate.

In the present invention, the above-mentioned styrenic polymer or a polymer composition in which the above-mentioned antioxidant, crosslinking agent, etc. are added as necessary is molded, and the obtained molded product is treated by irradiating it with an electron beam. do.

The shape, molding method, crystallinity, etc. of the molded product before electron beam treatment are not particularly limited, and can be appropriately determined depending on the characteristics required of the molded product to be subjected to the electron beam irradiation treatment. For example, the shape may be a film, a sheet, a laminated film, or a three-dimensional structure such as a container, and the molding method may be extrusion molding, injection molding, blow molding, etc. depending on the shape of the molded product. Inflation molding etc. can be applied. Furthermore, the degree of crystallinity may be either crystalline or amorphous.

Further, if necessary, it is possible to use a material that has been heat-treated after molding. Here, in injection molding, a molded product melted at a temperature higher than the melting point and molded at an arbitrary mold temperature of 200° C. or lower, or a molded product further heat-treated can also be used.

In the present invention, in particular, in addition to stretched films crystallized by stretching or stretched films further subjected to heat treatment to increase the degree of crystallinity, molded bodies obtained by blow molding or injection molding, T-dies, etc. are used. A sheet obtained by extrusion molding or the like is preferably used.

The above-mentioned stretched film is produced by the method described in Japanese Patent Application No. 63-3847, specifically, by melting a styrenic polymer mainly having a syndiotactic structure at a temperature higher than its melting point and then rapidly cooling it to form an amorphous film. It is obtained by creating a raw sheet and then stretching the sheet at a temperature above the glass transition temperature and below the melting point. In addition, this stretched film
The degree of crystallinity can be further increased by heat treatment at a temperature above the glass transition temperature and below the melting point.

Note that the parison before stretching may be either a hot parison or a cold parison.

In the present invention, it is necessary to irradiate the molded article with an electron beam. This electron beam irradiation treatment causes changes such as crosslinking in the styrene polymer that is the material of the molded product, and as a result, the thermal properties (solder resistance, hot water resistance, etc.) of the molded product are improved.

Here, unless electron beam irradiation is performed, the thermal properties of the molded article will not be sufficiently improved and the object of the present invention will not be achieved.

The equipment used for this electron beam processing may be either an electrostatic acceleration type or a high frequency acceleration type, the electron generation mechanism may be a hot cathode type, a cold cathode type, or a field emission type, and the processing method may be a scanning type. Alternatively, it may be of a non-scanning type. Among these, a combination in which the apparatus is an electrostatic acceleration type, the electron generation mechanism is a hot cathode type, and the processing method is a scanning type is particularly preferable.

The degree of electron beam irradiation is determined by the depth of treatment for the molded product, that is, the degree of crosslinking, etc. For example, when crosslinking only the surface of the molded product, the amount of electron beam irradiation is lower than when crosslinking the entire molded product. It may be less. It is most appropriate to express this electron beam irradiation amount as an absorbed dose, and usually this absorbed dose is 0.01 to 10 when a crosslinking agent is used.
Mrad (megarad), preferably adjusted to 1 to 100 Mrad when no crosslinking agent is used. The accelerating voltage is adjusted depending on the thickness of the molded product and the depth to be processed, but it is usually 100kV to 5M.
V (megavolt) is preferable. Furthermore, the amount of electrons (electron current) is preferably about 1 to 100 mA.

Furthermore, when the electron beam-treated films are laminated and used as a laminated film, resins to be laminated are selected in consideration of the required characteristics of the intended laminated film. For example, if high mechanical strength is required for the laminated film, polyester resin, polyamide resin, polycarbonate resin, polyolefin resin, or halogen-containing vinyl compound polymer should be selected as the thermoplastic resin, and gas barrier properties should be selected. If this is important, use polyester resins such as PET, polyamide resins, and PPS.

Polyvinyl alcohol resin and its derivatives, ethylene vinyl acetate, etc. should be selected, and if other thermoplastic resins with a low melting point are selected, a laminated film with good heat sealability can be obtained.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Production example (mainly production of a styrenic polymer having a syndiotactic structure) Toluene 2N as a solvent, 1 mmol of cyclopentadienyl titanium trichloride as a catalyst component, and 0.6 mol of methylaluminoxane as an aluminum atom are placed in a reaction vessel. In addition, styrene 3.6 at 20°C
2 was added and a polymerization reaction was carried out for 1 hour.

After the reaction was completed, the product was washed with a chlorine-methanol mixture to decompose and remove the catalyst component. Then, it is dried to form a polymer 33.
Obtained 0g.

Next, this polymer (polystyrene) was subjected to Soxhlet extraction using methyl ethyl ketone as a solvent to obtain an extraction residue of 95% by weight. This polymer has a weight average molecular weight of 290,00
0. The number average molecular weight is 158,000 and the melting point is 270.
It was °C. In addition, this polymer was found to have absorption at 145.35 ppm due to its syndiotactic structure based on carbon isotope nuclear magnetic resonance (C-NMR) analysis, and the syndiotactic structure in pentads was calculated from the peak area. City was 96%.

Example 1 100 parts by weight of the syndiotactic polystyrene powder obtained in the above production example and bis(2,
0.7 part by weight of 4-di-L-butylphenyl) pentaerythritol diphosphite and 0.1 part by weight of 2.6-dibutylphenyl-4-methylphenol were triblended. This powder was melted at 296°C and rapidly cooled to produce an amorphous pressed sheet.

Using this press sheet, electron beam processing was performed using a scanning electron beam processing apparatus at an acceleration voltage of 500 kV and an absorbed dose of 50 Mrad.

The heat resistance of the obtained press sheet is shown in the table.

Example 2 An amorphous sheet was obtained in the same manner as in Example 1, and stretched 3.5 times in length and width at 120'C using a table tenter.

This stretched film was used at an accelerating voltage of 500 kV.

Electron beam treatment was performed so that the absorbed dose was 40 Mrad at an electron current of 10 mA. The heat resistance of the obtained film is shown in the table.

Example 3 Electron beam treatment was performed in the same manner as in Example 2, except that the biaxially stretched film was heat treated at 260° C. under tension before being subjected to electron beam treatment.

The results are shown in the table.

Example 4 The mixed powder prepared in Example 1 was melted and pelletized. A test piece was made using this pellet using an injection molding machine.

Using this test piece, the acceleration voltage was 500 kV and the electron current was 10 m.
Electron beam treatment was performed at A so that the absorbed dose was 60 Mrad. The results are shown in the table.

Comparative Example 1 In Example 1, the heat resistance of the sheet before electron beam treatment was evaluated, and the results are shown in the table.

Comparative Example 2 In Example 2, the heat resistance of the film before electron beam treatment was evaluated, and the results are shown in the table.

Comparative Example 3 In Example 3, the heat resistance of the film before electron beam treatment was evaluated, and the results are shown in the table.

Comparative Example 4 In Example 4, the heat resistance of the test piece before electron beam treatment was evaluated, and the results are shown in the table.

〔Effect of the invention〕

As described above, the styrenic polymer molded article of the present invention has excellent heat resistance and is inexpensive, so it can be used for structural materials (2) food container materials (9) food packaging materials (single layer, multilayer) or It is useful as a material for electrical and electronic parts.

In particular, since it has excellent solder resistance, it can be effectively used in the production of electrical and electronic parts that require soldering.

Procedural correct fortune telling (voluntary) October 9, 1989

Claims (3)

[Claims] (1) A styrenic polymer molded article obtained by irradiating an electron beam onto a molded article mainly made of a styrenic polymer having a syndiotactic structure. (2) A method for producing a styrenic polymer molded article, which comprises molding a styrenic polymer mainly having a syndiotactic structure, and then irradiating the obtained molded article with an electron beam. (3) A styrenic polymer mainly having a syndiotactic structure is melted at a temperature above the melting point and then rapidly cooled to create an amorphous raw sheet, and then the sheet is stretched at a temperature above the glass transition temperature and below the melting point. 1. A method for producing a styrenic polymer molded article, which comprises irradiating a stretched film obtained by irradiating an electron beam.