JP2002128841A - Beverage container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a beverage container manufactured by injection blow molding which has a very good balance between container properties represented by container strengths, moldability and mold staining, and processability, and from which very little styrene monomer dissolves into a dummy solvent. SOLUTION: The beverage container featured by being manufactured by injection blow molding of a rubber modified styrene-base resin which has a gel content of 5-30%, rubber particles of 0.2-5 μm average diameter and a weight average molecular weight of the matrix of 100,000-500,000, and contains less than 200 ppm of styrene monomer, less than 3,000 ppm of total amount of styrene dimer and trimer, less than 500 ppm of styrene-base low molecular weight components in the range of 140-400 molecular weight other than styrene dimer and trimer and less than 1,000 ppm of residual hydrocarbon solvents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beverage container formed by injection blow molding of a rubber-modified styrene resin. More specifically, the present invention relates to a beverage container with a small amount of eluted material, which is injection-blown with a rubber-modified styrene resin having a low content of a styrene low molecular component such as a styrene monomer or a styrene oligomer and a small amount of a residual hydrocarbon solvent.

[0002]

2. Description of the Related Art Conventionally, a molded container formed by injection blow molding of a rubber-modified styrene resin has been used as a packaging container for fermented milk, lactic acid bacteria beverages, milk beverages and the like. With injection blow molding, a bottomed parison is first molded by injection molding, and while this parison is soft, it is transferred to a blow molding mold while being attached to a core (male mold for injection molding), and compressed air is sent from the core. This is a molding method for obtaining a hollow molded article. In this molding method, a higher temperature is required for releasing from the core than in general injection molding, and the temperature range is narrow. Japanese Patent Publication No. 48-1236 discloses a method for solving the problem of high-temperature mold release peculiar to the injection blow molding.

[0003] Further, since a molded container formed by injection blow molding is a thin-walled molded product, the strength of the container, particularly the strength of the mouth, often becomes a problem. As a method for solving this problem, Japanese Patent Publication No. 57-42654 is disclosed. Further, as important as the strength of the mouth, the strength of the container is the buckling strength. The buckling strength is related to the deformation when the products are stacked and the deformation during transportation of the products, and it is desirable that the buckling strength is high. However, mouth strength and buckling strength are of opposite nature. As a method of simultaneously satisfying both of these at a high level, Japanese Patent Application Laid-Open No. 10-76
No. 565 is disclosed.

The rubber-modified styrenic resins disclosed in these prior arts are produced by subjecting a styrenic monomer to thermal radical polymerization or radical polymerization using an initiator in the presence of a rubbery polymer. . In addition, there are two types of production processes: bulk polymerization and suspension polymerization. However, bulk radical polymerization is currently the mainstream because impurities such as dispersants are difficult to enter and cost is advantageous. I have. However, it is well known that such a radical polymerization method generally involves the formation of an oligomer during the production of a resin, and that styrene monomer tends to remain. For example,
Review articles (Encyclopedia of chemical technology, Kir
k-Othmer, Third Edition, John Wily & Sons, Vol. 21, p. 817)
According to the literature, thermal polymerization of styrene at 100 ° C. or higher involves by-products of oligomers such as styrene dimer and trimer, and the amount thereof is about 1% by weight. Specific oligomer components are mainly 1-phenyl-4- (1′-
Phenylethyl) tetralin and 1,2-diphenylcyclobutane, and 2,4-diphenyl-1-
Butene and 2,4,6-triphenyl-1-hexene are allegedly present.

In general, in the bulk radical polymerization process, polymerization is usually carried out at 80 to 180 ° C., and then a small amount of a contained solvent or unreacted monomer is removed by heating and volatilizing to remove the polymer. Most of the solvent, unreacted monomers, etc. are recycled, but some remain in the polymer. Also,
Oligomers such as dimers, trimers, tetramers, and pentamers by-produced hardly volatilize, and most of them remain in the polymer. When the rubber-modified styrenic resin thus produced is analyzed, residues, impurities and by-products during polymerization are detected from the raw materials. Specifically, styrene, α-methylstyrene, n-propylbenzene, is
o-propylbenzene, 2,4-diphenyl-1-butene, 1,2-diphenylcyclobutane, 1-phenyltetralin, 2,4,6-triphenyl-1-hexene,
1,3,5-triphenylbenzene, 1-phenyl-4
-(1'-phenylethyl) tetralin and the like are contained in such a rubber-modified styrenic resin.

As described above, the rubber-modified styrene-based resin of the radical polymerization method which is currently widely used contains a large amount of low molecular components composed of monomers and oligomers due to its production method. Furthermore, rubber-modified styrenic resins of these radical polymerization methods generally have poor stability, and the amount of low molecular components such as monomers and oligomers in the resin tends to increase due to mechanical history or thermal history during molding. . Low-molecular components newly generated during molding also have the same problems as low-molecular components generated during polymerization. Injection blow molding using such a rubber-modified styrene-based resin containing a large amount of low molecular components causes various problems due to the low molecular components contained in the resin. For example,
During the injection blow molding, it may adhere to the mold as an oily substance, resulting in a decrease in moldability, or may adhere to the surface of the molding container to cause appearance trouble. Also,
The low-molecular component contained in the resin diffuses or bleeds from the inside of the molded article to the surface, which may cause a problem that printing is difficult to take or printing is easily peeled off. Furthermore, low molecular components contained in the resin may be eluted or volatilized from the molding container, and reduction thereof is desired.

[0007] In contrast to these radical polymerization methods, a method for producing a styrene-based resin by an anionic polymerization method using organic lithium or the like has long been known in the art. For example, US Pat. No. 5,391,655, US Pat. No. 5,089,572, US Pat. No. 4,883,8
No. 46, U.S. Pat. No. 4,748,222,
U.S. Pat. No. 4,205,016, U.S. Pat.
The details are introduced in US Pat. No. 00,713, US Pat. No. 4,016,348, US Pat. No. 3,954,894, US Pat. No. 4,859,748, etc. There was no disclosure about a styrene-based low molecular component for the purpose of the present application. Further, in recent years,
0-110074, International Application PCT / JP97 /
00796, JP-A-2000-143725 and the like, styrene-based polymer obtained by anionic polymerization method using organolithium, compared with styrene-based polymer by radical polymerization method, styrene dimer and styrene trimer It is disclosed that the content is low, but a molecular weight of 140 to 400 other than styrene dimer and trimer.
No disclosure is made with respect to the styrene-based low molecular weight component in the range.

JP-A-4-22614 discloses a composition comprising an anion-polymerized polystyrene having a narrow molecular weight distribution and a radical-polymerized high-impact polystyrene with improved moldability. In addition, international application PCT / EP
No. 95/04539 discloses a composition composed of an anion-polymerized polystyrene and a radical-polymerized high-impact polystyrene with a low residual styrene monomer. However, these prior arts did not disclose styrene dimers and trimers. Further, there is no disclosure of a styrene-based low molecular weight component having a molecular weight of 140 to 400 other than styrene dimer and trimer. Furthermore, there is no disclosure about an injection blow molded container.

As a result of intensive studies by the present inventors, it has been found that even in anionic polymerization using organolithium, formation of styrene dimer and trimer occurs at a certain temperature and monomer concentration which are practical polymerization conditions. . In addition to styrene dimers and trimers, it has been found that styrene-based low molecular components unique to the anionic polymerization method are produced. This is mainly produced by reacting a specific solvent or a trace amount of impurities contained therein with a styrene monomer in the coexistence of organolithium, and has a structure that can no longer be said to be a styrene oligomer. That is, even in the anionic polymerization method, the obtained styrene-based resin has a problem that a styrene-based low-molecular component having a molecular weight of 140 to 400 other than styrene dimer and trimer is contained in a nonnegligible amount,
As a result of the study by the present inventors, it became clear.

[0010]

That is, an object of the present invention is to solve the above-mentioned problems and to provide a rubber-modified styrene-based resin having a low content of styrene-based low-molecular components such as styrene monomer and styrene oligomer and a small amount of residual hydrocarbon solvent. An object of the present invention is to provide a beverage container which is injection-blown with a resin and has a small amount of eluted material.

[0011]

SUMMARY OF THE INVENTION The invention is as set forth in the appended claims. That is, the gel content is 5-30.
%, A rubber modified styrene resin having an average rubber particle diameter of 0.2 to 5 μm, a weight average molecular weight of a matrix phase of 100,000 to 500,000, and a styrene monomer contained in the resin is less than 200 ppm, a styrene dimer , The total amount of the trimers is less than 3000 ppm, the styrene-based low-molecular components having a molecular weight of 140 to 400 other than the styrene dimer and the trimer are less than 500 ppm, and the residual hydrocarbon solvent is 1 ppm.
The present invention relates to a beverage container obtained by subjecting a rubber-modified styrene resin having a concentration of less than 000 ppm to injection blow molding.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a beverage container according to the present invention will be described in detail. The gel content of the rubber-modified styrenic resin used in the present invention is 5 to 30% by weight.
It is. Preferably it is 7 to 25% by weight. If the gel content is too small, the strength of the mouth of the container is decreased, which is not preferable. If it is too large, the buckling strength of the container is unfavorably reduced.

The rubber-modified styrene resin used in the present invention has an average rubber particle diameter of 0.2 to 5 μm.
Preferably from 0.5 to 4 μm, more preferably from 0.9 to
3 μm. In addition, the rubber particles are 0.2 to 0.9 μm
May have a two-peak distribution consisting of a small particle portion and a large particle portion of 1 to 5 μm. If the rubber particle diameter is too small, the strength at the mouth of the container decreases, which is not preferable. If it is too large, the buckling strength of the container decreases, which is not preferable. The weight average molecular weight of the matrix phase of the rubber-modified styrene resin used in the present invention is 100,000 to 500,000. Preferably it is 120,000 to 400,000, more preferably 140,000 to 300,000. If the weight average molecular weight of the matrix phase is too low, the mouth strength of the container, the buckling strength is undesirably reduced,
If it is too high, the fluidity is reduced, and molding defects are likely to occur, which is not preferable.

The rubber-modified styrenic resin used in the present invention contains less than 200 ppm of styrene monomer, and the total amount of styrene dimer and trimer is 3000 p.
pm, molecular weight other than styrene dimer and trimer 1
Styrene low molecular weight components in the range of 40 to 400 are 500p
pm, residual hydrocarbon solvent is less than 1000 ppm. Preferably, the styrene monomer contained is 150
ppm, the total amount of styrene dimer and trimer is 2
Less than 500 ppm, less than 300 ppm of styrene-based low molecular components other than styrene dimer and trimer having a molecular weight of 140 to 400, and less than 500 ppm of residual hydrocarbon solvent. More preferably, the styrene monomer contained is less than 100 ppm, the total amount of styrene dimer and trimer is less than 2000 ppm, the styrene-based low molecular weight component having a molecular weight of 140 to 400 other than styrene dimer and trimer is less than 100 ppm, and the remaining hydrocarbon solvent Is 2
Less than 00 ppm.

When the content of these low molecular components, that is, styrene low molecular components other than styrene monomer, styrene dimer, trimer, and styrene dimer and trimer in the molecular weight range of 140 to 400, and the content of residual hydrocarbon solvent is large, At the time of injection blow molding, it may adhere to the mold as an oily substance to lower moldability, or may adhere to the surface of the molding container to cause appearance trouble. In addition, the low molecular components contained in the resin are diffused or bleed from the inside of the molded article to the surface, which may cause a problem that printing is difficult to take or that printing is easily peeled. Further, the low molecular components contained in the resin may be eluted or volatilized from the molding container. Styrene dimer has a molecular weight of 208 and 2,4-diphenyl-1-
Butene, cis-1,2-diphenylcyclobutane, trans-1,2-diphenylcyclobutane, 1-phenyltetralin. Styrene trimer has a molecular weight of 3
12, 2,4,6-triphenyl-1-hexene, 1-phenyl-4- (1′-phenylethyl) tetralin (including four isomers), 1,3,5-triphenyl-cyclohexane And the like.

The styrene low molecular weight component having a molecular weight of 140 to 400 other than styrene dimer and trimer is a hydrocarbon compound having 1 to 3 aromatic rings in the molecule.
Specifically, as a hydrocarbon compound having two aromatic rings, 1,3-diphenylpropane, 1,2-diphenylcyclopropane, 1,3-diphenylbutane, and as a hydrocarbon compound having three aromatic rings, 1,3 , 5-triphenylpentane, 1,3,5-triphenylhexane, 1,
2,4-triphenylcyclopentane and the like.
These styrenic low molecular weight components are mainly formed by the reaction of impurities contained in monomers and solvents with styrene monomers in the presence of organolithium, and have a structure that can no longer be said to be styrene oligomers. are doing.
For example, one or two molecules of styrene are added to contained toluene, and 1,3-diphenylpropane or 1,3-diphenylpropane is added.
3,5-Triphenylpentane is formed. Also, one or two molecules of styrene are added to ethylbenzene to produce 1,3-diphenylbutane and 1,3,5-triphenylhexane.

In addition, although the formation mechanism is not always clear, 1,2-diphenylcyclopropane,
2,4-triphenylcyclopentane, 2,4-diphenylpentane and the like are also found in the composition. The residual hydrocarbon solvent is used as a solvent during the production of the impact-resistant styrene resin and the styrene resin, and remains in the resin without being completely removed by volatilization in the desolvation step. Specific examples include C6-C9 aromatic hydrocarbons and C5-C9 alicyclic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, n-propylbenzene, iso-propylbenzene, cyclohexane, methylcyclohexane, and the like. Can be

The rubber-modified styrene resin used in the present invention can be obtained from 10 to 60% by weight of impact-resistant styrene resin (A) and 90 to 40% by weight of styrene resin (B). The impact-resistant styrene resin (A) used here is obtained by radical polymerization of a styrene monomer in the presence of a rubbery polymer. The rubbery polymer used is a polybutadiene, a random or block copolymer of styrene butadiene, a random or block copolymer of α-methylstyrene-butadiene, a random or block copolymer of styrene-isoprene,
And hydrogenated products of the above polymers, ethylene-propylene rubber, ethylene-propylene-diene rubber, acrylic rubber, and the like, but typical examples are polybutadiene, a random or block copolymer of styrene butadiene, And their hydrogenated products.

The gel content of the impact-resistant styrenic resin (A) used in the present invention is preferably 20 to 50% by weight. More preferably, it is 25 to 45% by weight. If the gel content is too small, the strength of the mouth of the molded container is unpreferably reduced, and if it is too large, the buckling strength of the molded container is undesirably reduced. The intrinsic viscosity of the matrix phase of the impact-resistant styrene resin (A) used in the present invention is preferably 0.45 to 0.9 dl / g.
More preferably, it is 0.5 to 0.85 dl / g. If the intrinsic viscosity of the matrix phase is too low, the mouth strength and the buckling strength of the molded container are undesirably lowered, and if it is too high, poor appearance is likely to occur due to poor dispersion.

Styrene resin (B) used in the present invention
Is generally preferably 100,000 to 600,000 in terms of weight average molecular weight. More preferably 120,000 to 40
It is preferably in the range of 140,000 to 300,000. If the weight average molecular weight is too low, the strength at the mouth and the buckling strength of the molded container are undesirably reduced. On the other hand, if the weight average molecular weight is too high, the fluidity becomes insufficient, and molding defects tend to occur, which is not preferable. The molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight to the number average molecular weight of the styrene resin (B) used in the present invention is preferably in the range of 1.5 to 5.0. More preferably, it is in the range of 2-4. If the molecular weight distribution is too narrow, the moldability decreases, and if the molecular weight distribution is too wide, the specific resin performance, for example, the flow characteristics at the time of molding decreases, which is still unfavorable.

Styrene resin (B) used in the present invention
Is preferably less than 100 ppm. More preferably less than 50 ppm,
Particularly preferred is less than 20 ppm. The styrene dimer and trimer contained in the styrene resin (B) used in the present invention are preferably less than 500 ppm. It is more preferably less than 300 ppm, particularly preferably less than 200 ppm. Further, a styrene dimer contained in the styrene resin (B) used in the present invention,
It is preferable that the amount of the styrene-based low molecular weight component having a molecular weight of 140 to 400 other than the trimer is less than 500 ppm. It is more preferably less than 300 ppm, particularly preferably less than 200 ppm.

The residual hydrocarbon solvent contained in the styrene resin (B) used in the present invention is 1000 ppm.
It is preferably less than. More preferably 300p
pm, particularly preferably less than 100 ppm. If the content of these low-molecular components, i.e., styrene monomer, styrene dimer, trimer, styrene dimer and styrene-based low-molecular components having a molecular weight in the range of 140 to 400 other than the trimer and the content of the remaining hydrocarbon solvent are large, oil during injection blow molding may become oily. In some cases, the substance adheres to the mold to lower the moldability, or adheres to the surface of the molding container to cause appearance trouble. In addition, the low molecular components contained in the resin are diffused or bleed from the inside of the molded article to the surface, which may cause a problem that printing is difficult to take or that printing is easily peeled. Further, the low molecular components contained in the resin may be eluted or volatilized from the molding container.

Styrene resin (B) used in the present invention
Can be produced by an anionic polymerization method using an organolithium initiator. The process of the anionic polymerization method is not particularly limited. Generally, it is carried out by the following process. For example, a complete batch polymerization method in which the entire amount of the monomer and the initiator is charged into the reaction tank and then polymerization, a semi-batch polymerization method in which the reaction tank is charged with part or all of the initiator, and then polymerization is performed while the monomer is additionally charged, and complete stirring. The raw material system (monomer and initiator) is continuously charged into the reaction tank in the state, and the same amount of the production system (polymer solution) is taken out while continuously stirring, or the reaction raw material system is started from one end of the tubular reaction tank. , And the product system is taken out from the other end. A continuous polymerization method of plug flow, or a series connection process thereof is conceivable.

Styrene resin (B) used in the present invention
Can be preferably prepared by a combined process in which a continuous reactor with complete stirring and then a plug-flow continuous reactor are combined. In the continuous polymerization process with complete stirring, the molecular weight distribution of the obtained polymer is broadened, and the remaining monomer can be efficiently converted in the continuous polymerization process in the next plug flow. Broadening the molecular weight distribution helps to improve the processability of the resin, and complete conversion of the monomer can eliminate low molecular weight components derived from the monomer mixed into the resin. The complete stirring mentioned here is not limited to a narrow meaning. This means that the initiator has a broad residence time distribution, whereby the molecular weight distribution of the polymer is significantly broadened. Specifically, it means stirring conditions under which the molecular weight distribution of the obtained polymer, that is, the ratio Mw / Mn of the weight average molecular weight to the number average molecular weight is 1.5 or more.

Styrene resin (B) used in the present invention
The organic lithium compound used for the production of is a so-called organometallic compound of lithium having a carbon-lithium bond. More specifically, examples thereof include an alkyl lithium and an alkyl-substituted phenyl lithium compound. Preferred examples of the alkyl lithium include ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, benzyl lithium and the like. The amount of the organolithium initiator used depends on the molecular weight of the polymer to be obtained. That is, the molecular weight of the polymer is basically determined by the composition ratio of the monomer and the organolithium initiator. The amount of organolithium used per kg of monomer is preferably in the range of 0.5 to 200 mmol, more preferably 1 to 100 mmol, and particularly preferably 2 to 20 mmol.
In the millimolar range.

If the amount of organolithium is reduced below this range, the polymerization rate is undesirably reduced, and the molecular weight of the resulting polymer is undesirably increased. Further, increasing the amount of the organic lithium beyond this range is not preferable because the production cost is increased or the molecular weight of the obtained polymer is extremely reduced. In the polymerization using organic lithium as a polymerization initiator, one molecule of the initiator basically generates one molecule of the polymer, and thus the amount of the organic lithium used depends on the molecular weight of the target polymer. However, it is also known that by adding an appropriate amount of a hydrocarbon having active hydrogen, the active site shifts and the initiator efficiency can be increased by a certain amount. The hydrocarbon having active hydrogen that can be used for such a purpose is, specifically, a hydrocarbon compound in which a hydrogen atom is bonded to a carbon atom at the α-position to a phenyl group or an allyl group. Preferred specific examples are toluene,
Examples thereof include ethylbenzene, xylene, tetralin, and propylene.

Styrene resin (B) used in the present invention
The main component of the monomer used in the above is styrene. However, other copolymerizable monomers other than styrene may be included. Examples thereof include vinyl aromatic hydrocarbons other than styrene, conjugated dienes, methacrylates, and the like. The use of these copolymerized monomers is important for the heat resistance, softening temperature, impact strength, rigidity,
It may be useful for adjusting workability and the like.

The industrial raw materials or the commercially available styrene monomers contain the corresponding acetylenes (phenylacetylene in the case of styrene). When phenylacetylene is polymerized with n-butyllithium using styrene as a monomer, it deactivates n-butyllithium,
And / or acts as a chain transfer agent, reducing the efficiency of the n-butyllithium used and / or producing a low molecular weight polymer. In order to obtain the styrene-based resin (B) used in the present invention, the phenylacetylene-based compound is preferably less than 200 ppm based on the styrene-based monomer. More preferably less than 150 ppm,
Most preferably it is less than 100 ppm. 200 ppm
When a styrene-based monomer containing phenylacetylene is used, the above-mentioned problems become apparent, low molecular components and the like in the product increase, and thermal stability during molding and the like is impaired.

Styrene resin (B) used in the present invention
May be a bulk polymerization containing no solvent. However, in order to lower the viscosity and facilitate stirring and heat removal, polymerization in a solution is generally preferred. Basically, the solvent that can be used during polymerization is a hydrocarbon solvent that is inert to the organolithium initiator and can dissolve the monomer and the resulting polymer.It maintains a liquid state during polymerization and volatilizes during the desolvation step after polymerization. A solvent that can be easily removed is preferably used. Specifically, a C6-C9 aromatic solvent, a C5-C9 alicyclic hydrocarbon solvent such as benzene, toluene, xylene, ethylbenzene, cyclohexane, methylcyclohexane, etc., and further a C4-C8 cyclic ether such as tetrahydrofuran Etc. can be preferably used. Particularly preferred polymerization solvents are alicyclic hydrocarbon solvents among these hydrocarbon solvents. In addition, a mixture of these solvents or these solvents may partially contain an aliphatic hydrocarbon having no cyclic structure. Addition of an ether compound or a tertiary amine compound can improve the polymerization activity of the organolithium on the monomer.

The amount of the polymerization solvent used is preferably in the range of 0.1 to 3 kg per 1 kg of the monomer, more preferably 0.5 to 2.0 kg, and particularly preferably 0.67 to 1.5 kg.
Kg range. If the amount of the polymerization solvent is small, heat removal and stirring become difficult, and if the amount of the polymerization solvent is large, the amount of the solvent to be removed after the polymerization increases, and the amount of thermal energy increases, which is not preferable. The polymerization temperature is preferably in the range of 50 to 120C, more preferably 60 to 110C, and particularly preferably 70 to 90C. When the polymerization temperature is extremely low, the reaction rate is reduced, and the method is not practical. On the other hand, when the polymerization temperature is extremely high, the production amount of the styrene-based low-molecular component increases, and the reaction rate decreases due to decomposition of the initiator, which is also not preferable. Further, if the temperature is higher than 110 ° C., the polymer may be colored, which is not preferable depending on the use.

Styrene resin (B) used in the present invention
In the case of polymerizing, the solution viscosity during polymerization is generally extremely high, depending on the monomer concentration of the raw material system. For this reason, it is often difficult to remove the heat of polymerization using only a jacket attached to a normal reaction tank. A known method can be used as a method for increasing the heat removal capability of the equipment. For example, a method in which a heat removal coil is stretched in the reaction vessel, an external circulation jacket is provided separately from the reaction vessel jacket, or a reflux condenser is provided can be preferably used. The pressure in the reactor must be sufficient to keep the system in the liquid phase. When a reflux condenser is used for removing the reaction heat, a reduced pressure can be used if necessary.

Styrene resin (B) used in the present invention
Is produced by an anionic polymerization method using an organic lithium initiator, a carbon-lithium bond remains at the polymer terminal after the polymerization. If this is left as it is, it may be subjected to air oxidation or thermal decomposition at the finishing stage or the like, which may cause a decrease in stability or coloring of the obtained styrene resin. After the polymerization, it is preferable to stabilize the active terminal of the polymer, that is, the carbon-lithium bond. For example, addition of a compound having an oxygen-hydrogen bond such as water, alcohol, phenol, and carboxylic acid, an epoxy compound, an ester compound, a ketone compound, a carboxylic anhydride, and a compound having a carbon-halogen bond can be expected to have similar effects. . The use amount of these additives is preferably about equivalent to about 10 times equivalent to the carbon-lithium bond. Too much is not only disadvantageous in terms of cost, but also
In many cases, the incorporation of the remaining additives becomes an obstacle.

Coupling reaction with a polyfunctional compound utilizing a carbon-lithium bond can be used to increase the molecular weight of the polymer and to form a branched structure of the polymer chain. The polyfunctional compound used for such a coupling reaction can be selected from known compounds. Examples of the polyfunctional compound include polyhalogen compounds, polyepoxy compounds, mono- or polycarboxylic acid esters, polyketone compounds, mono- or polycarboxylic anhydrides, and alkoxy compounds of silicon or tin. Specific examples include silicon tetrachloride, di (trichlorosilyl) ethane, 1,3,5
-Tribromobenzene, epoxidized soybean oil, tetraglycidyl 1,3-bisaminomethylcyclohexane, dimethyl oxalate, tri-2-ethylhexyl trimellitate, pyromellitic dianhydride, diethyl carbonate and the like.

Further, an alkali component derived from organolithium,
For example, lithium oxide or lithium hydroxide can be neutralized and stabilized by adding an acidic compound. Examples of such acidic compounds include carbon dioxide, boric acid, various carboxylic acid compounds, and the like. In some cases, these additions can particularly improve water absorption turbidity and coloring resistance. The styrene-based resin (B) used in the present invention may be any of various types of styrene-based resins known for use in order to improve their thermal or mechanical stability, antioxidant properties, weather resistance, and light resistance. Agents can be added. Examples thereof include phenol stabilizers, phosphorus stabilizers, nitrogen stabilizers, and sulfur stabilizers.

JP-A-7-292188 discloses that the addition of 2,4,6-trisubstituted phenol is particularly advantageous as a method for stabilizing polystyrene. Preferred examples of the 2,4,6-trisubstituted phenol include 2,6-di-tert-butyl-4-methylphenol and triethylene glycol-bis- [3- (3-tert-butyl-).
5-methyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate, 1,3,5
-Trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene, n-octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2-tert-butyl-6- (3
-T-butyl-2-hydroxy-5-methylbenzyl)
-4-methylphenyl acrylate, 2 [1- (2-hydroxy3,5-di-t-pentylphenyl)]-4,
6-di-t-pentylphenyl acrylate, tetrakis [methylene 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 3,9bis [2- {3- (t-butyl- 4-hydroxy-5-methylphenyl) propynyloxy {-1,1-dimethylethyl] -2,4,8,10-tetraoxo [5,5] undecane, 1,3,5-tris (3 ′, 5 ′ -Di-t-
Butyl-4'-hydroxybenzyl) -s-triazine-2,4,6 (1H, 2H, 3H) -trione,
1,4-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane, 4,4'-butylidenebis (3-methyl-6-t-butylphenol) and the like.

These stabilizers can be mixed after the recovery of the polymer. However, the addition at the solution stage after the polymerization is particularly preferable in that the mixing is easy and the deterioration of the polymer in the solvent recovery step can be suppressed. After the completion of the polymerization, the unreacted monomers and the solvent are volatilized and removed from the polymer and recovered. Known methods can be used for volatilization. As the volatilization removing device, for example, a method of flashing in a vacuum tank and a method of volatilization removal from a vent port using an extruder can be preferably used. Although it depends on the volatility of the solvent, the temperature is generally 150 to 300 ° C., preferably 18 to 300 ° C.
0-260 ° C, degree of vacuum 0-normal pressure, preferably 100P
Volatile components such as solvent and residual monomer are volatilized and removed at a to 50 KPa. It is also effective to connect the devolatilizers in series and arrange them in two stages. Further, a method in which water is added between the first stage and the second stage to increase the volatility of the second stage can also be used. After removing the volatile components in the flash tank, an extruder with a vent may be further used to remove the remaining volatile components. The styrene-based resin from which volatile components such as a solvent have been removed by devolatilization can be finished into pellets by a known method.

The styrenic resin (B) used in the present invention may be mixed with known additives, if necessary. Examples include dyes, pigments, fillers, lubricants, release agents, plasticizers, antistatic agents and the like. As a method for mixing the impact-resistant styrene-based resin (A) and the styrene-based resin (B) obtained as described above, the components independently obtained are mixed with a known device, for example, a kneader, a Banbury mixer, a single-shaft. Alternatively, they can be mixed by melt-kneading with a twin-screw extruder or the like. Alternatively, it can be obtained by mixing a polymerization liquid of the impact-resistant styrene resin (A) and a polymerization liquid of the styrene resin (B), continuing the polymerization as necessary, and devolatilizing and drying by a known method. . In some cases, pellets of the impact-resistant styrene resin (A) and pellets of the styrene resin (B) may be dry blended by a known method.

The rubber-modified styrenic resin used in the present invention contains 1.0% mineral oil from the viewpoint of moldability.
Preferably, it is contained in an amount of about 4.0% by weight. Preferably,
It is 1.5 to 3.5% by weight. If the content of the mineral oil is too large, the heat-resistant temperature decreases, the container is easily deformed, and stringing is apt to occur during injection blow molding, which is not preferable. If the amount of mineral oil is too small, the strength of the mouth of the container is undesirably reduced. Various mineral oils can be used, but the number average molecular weight is preferably in the range of 375 to 425. Such mineral oil is ASTM D1160 (10m
2.5% by weight as measured in mHg)
90 ° C.

The rubber-modified styrene resin used in the present invention preferably contains a mixture of a higher fatty acid and a metal salt of a higher fatty acid from the viewpoint of releasability. The mixing ratio of the higher fatty acid and the higher fatty acid metal salt is 1/3 to
3.5, and the amount is preferably 0.1 to 0.4% by weight. If the amount is too small, the releasability is poor, which is not preferable. If the amount is too large, thermal discoloration and thermal deterioration occur, which is not preferable. Here, the higher fatty acids are those having 12 to
22 saturated linear carboxylic acids. The higher fatty acid metal salt is a metal salt of the above higher fatty acid, and the kind of the metal is not particularly limited.
Magnesium and zinc are mentioned as examples. In the rubber-modified styrene resin used in the present invention, various additives usually used as needed, for example, stabilizers, dyes, pigments, fillers, lubricants, release agents, plasticizers, antistatic agents, An antioxidant and the like can be added.

[0040]

The embodiments of the present invention will be specifically described below with reference to examples and comparative examples. However, these are only examples and do not limit the technical scope of the present invention in any way. According to the following Reference Examples 1 to 7, impact-resistant styrene resins A1 to A3 and styrene resins B1 to B4 were obtained.

[0041]

[Reference Example 1] Production of impact-resistant styrenic resin A1 Polybutadiene (Nipol 12 manufactured by Zeon Corporation)
20SL) in styrene, then ethylbenzene and 1,1-bis (t-butylperoxy) 3,3,3.
A small amount of 5-trimethylcyclohexane was added to finally prepare a polymerization stock solution having the following composition. (Unit is parts by weight) • Polybutadiene: 12.0 • Styrene: 76.0 • Ethylbenzene: 12.0 • 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane: 0.0
1 The above polymerization stock solution was continuously fed to a three-tank reactor equipped with a stirrer having an inner volume of 6.2 liters. The temperature inside the reactor was controlled so that the solid content concentration at the outlet of the first layer reactor was 35% by weight. The solid concentration at the outlet of the reactor in the final tank is 7
The temperature in the reactor was controlled so as to be 9% by weight. Next, the mixture was fed into a devolatilizer under a vacuum of 230 ° C. to remove unreacted styrene and ethylbenzene, and granulated by an extruder to obtain a pellet-shaped impact-resistant styrene resin A1. The gel content was determined from the toluene insoluble content of A1 to be 42.1% by weight. The intrinsic viscosity of the matrix phase determined from the methyl ethyl ketone soluble matter is 0.74 dl /
g. The weight-average rubber particle diameter determined from a transmission electron micrograph was 2.2 μm.

[0042]

Reference Example 2 Production of Impact Resistant Styrene Resin A2 Polybutadiene (Nipol 12 manufactured by Zeon Corporation)
20SL) in styrene, then ethylbenzene and 1,1-bis (t-butylperoxy) 3,3,3.
A small amount of 5-trimethylcyclohexane was added to finally prepare a polymerization stock solution having the following composition. (Unit is parts by weight) ・ Polybutadiene: 5.0 ・ Styrene: 83.0 ・ Ethylbenzene: 12.0 ・ 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane: 0.0
1 The above polymerization stock solution was continuously fed to a three-tank reactor equipped with a stirrer having an inner volume of 6.2 liters. The temperature in the reactor was controlled so that the solid concentration at the outlet of the first layer reactor was 30% by weight. The solid concentration at the outlet of the reactor in the final tank is 8
The temperature inside the reactor was controlled so as to be 1% by weight. Subsequently, the mixture was fed into a devolatilizer under a vacuum at 230 ° C. to remove unreacted styrene and ethylbenzene, and granulated by an extruder to obtain a pellet-shaped impact-resistant styrene resin A2. The gel content was determined from the toluene insoluble content of A2 to be 14.3% by weight. The intrinsic viscosity of the matrix phase determined from the soluble matter of methyl ethyl ketone is 0.71 dl /
g. The weight-average rubber particle diameter determined from a transmission electron micrograph was 3.0 μm.

[0043]

Reference Example 3 Production of Impact-Resistant Styrene-Based Resin A3 Polybutadiene (Dien 55AG, manufactured by Asahi Kasei Corporation)
In styrene, then ethylbenzene and 1,
A small amount of 1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane was added to finally prepare a polymerization stock solution having the following composition. (Units are parts by weight) ・ Polybutadiene: 3.0 ・ Styrene: 85.0 ・ Ethylbenzene: 12.0 ・ α-methylstyrene dimer: 0.03 ・ 1,1-bis (t-butylperoxy) 3,3 , 5-trimethylcyclohexane: 0.0
15 The above polymerization stock solution was continuously fed to a three-tank reactor equipped with a stirrer having an inner volume of 6.2 liters. The temperature inside the reactor was controlled so that the solid concentration at the outlet of the first layer reactor was 25% by weight. The solid concentration at the outlet of the reactor in the final tank is 8
The temperature inside the reactor was controlled to be 2% by weight. Next, the mixture was fed to a devolatilizer at 230 ° C. under vacuum to remove unreacted styrene and ethylbenzene, and the mixture was granulated with an extruder to obtain a pellet-shaped impact-resistant styrene resin A3. The gel content was determined from the toluene-insoluble content of A3 to be 18.0% by weight. The intrinsic viscosity of the matrix phase determined from the methyl ethyl ketone soluble matter is 0.73 dl /
g. The weight average rubber particle diameter determined from a transmission electron micrograph was 2.8 μm.

[0044]

Reference Example 4 Production of Styrene-Based Resin B1 A 2-liter capacity complete reaction tank equipped with a stirrer and a 1-liter plug-flow type reaction vessel equipped with a stirrer were used. Coupled in series. The temperature of both reactors was controlled at 80 ° C. A mixture of a styrene monomer (phenylacetylene in the styrene was 31 ppm) and cyclohexane in a 50/50 weight ratio as a polymerization solvent was fed to the first reaction tank at a flow rate of 1.78 kg / hour. Separately, a cyclohexane solution of n-butyl lithium as an organic lithium initiator was added to 1 kg of a styrene monomer.
Per 10 mmol / mol. The reaction solution flowing out of the first reaction tank was subsequently put into the second reaction tank and passed through a plug flow. The conversion rate of the monomer into the polymer at the time of flowing out of the first reaction vessel was 98% on average, and the conversion rate after passing through the second reaction vessel was 99.99% or more. The anion active terminal was inactivated by adding methanol three times the amount of lithium to the obtained polymer solution. Thereafter, the polymer solution was subjected to a heat treatment at 240 ° C. in a reduced pressure flushing tank to remove volatile components. Further, 0.5% by weight of water was added to and mixed with the polymer, and the remaining volatile components were removed through an extruder equipped with a reduced-pressure vent at 250 ° C.

[0045]

Reference Example 5 Production of styrene resin B2 Reference Example 4 except that ethylbenzene was used as a polymerization solvent.
Was performed in the same manner as described above.

Reference Example 6 Production of Styrene Resin B3 In a 2-liter reactor equipped with a stirrer, 0.75 kg of a styrene monomer and 0.1 g of a polymerization solvent were added at room temperature.
75 kg of ethylbenzene and 5 mmol of n-butyllithium as an organolithium initiator are charged. Thereafter, when the temperature was gradually increased with stirring, the temperature was raised from about 50 ° C. due to internal heat generation, and the final temperature reached 133 ° C.
Thereafter, the temperature was gradually lowered to 100 ° C., for a total of 1.5
The reaction was continued for hours. The processing conditions after the polymerization were the same as in Reference Example 4.

[0046]

[Reference Example 7] Production of styrene resin B4 Ethylbenzene was used as a polymerization solvent, and the temperature of both reaction tanks was 1
The procedure was performed in the same manner as in Reference Example 4 except that the temperature was 22 ° C. The molecular weight distribution of the polymer of the styrene-based resin thus obtained (indicated by the ratio Mw / Mn between the weight-average molecular weight and the number-average molecular weight), the content of the monomer, the low-molecular-weight styrene-based component and the residual hydrocarbon solvent are determined. And analyzed by gas chromatography. The results of the analysis are shown in Table 1.

[0047]

[Table 1]

[0048]

[Examples 1 to 4],

Comparative Examples 1 to 4 Impact-resistant styrene resins (abbreviated as A1, A2 and A3 in Table 2) and styrene resins (B1 and B2 in Table 2) obtained in Reference Examples 1 to 7. B2, B
3, abbreviated as B4. ) Were mixed at the compounding ratio shown in Table 2 to obtain a rubber-modified styrene resin. At this time, 0.3 part by weight of a mixture of stearic acid / calcium stearate = 1/3 and 3.0 parts by weight of mineral oil were added per 100 parts by weight of the rubber-modified styrene resin. The weight average molecular weight of the matrix phase was measured from the methyl ethyl ketone soluble matter of the obtained rubber-modified styrene resin.
The gel content can be determined from the toluene-insoluble content of the rubber-modified styrene resin, or can be calculated from the gel content and the compounding ratio determined from the toluene-insoluble content of the impact-resistant styrene resin. Table 2 shows the results.

Using the obtained rubber-modified styrenic resin, SG125-NP [manufactured by Sumitomo Heavy Industries, Ltd.], a circular parting line having a diameter of 43 mm, a body diameter of 48 mm and a height of 90 mm under the following conditions. Is 10mm from the bottom
138 cm ³ of beverage container with two parting lines on the side at a height of. Table 2 shows the results of measuring the moldability at that time and the strength of the obtained container.・ Cylinder temperature (from nozzle side): 240-240-
230-220 ° C ・ Hot runner temperature: 240 ° C ・ Core heating temperature: 150 ° C ・ Cavity temperature: 50 ° C

1) Mouth Impact Strength of Container Using a Dupont impact strength measuring device, the strength of the side of the mouth on the parting line of the container is measured. Load is 20
0g, missile tip diameter is イ ン チ inch, the container is divided by mold surface and container number, and the lowest value at which cracking occurs is measured for 6 containers for each container number, and then the average value is calculated . 2) Buckling strength of container The compression jig of the tensile-compression tester is made into a flat plate, and the container is compressed at a speed of 200 mm / min so that the container comes into vertical contact. A container for two shots is used for the measurement, and the measured values are averaged. 3) Evaluation of Formability Continuous molding was performed in one cycle for 6 seconds, and the possibility of continuous molding was observed from the mouth smoothness, uneven thickness, and stringing of the 20th shot. The evaluation criteria are shown below. ：: Continuous molding is possible without any problem in the smoothness, unevenness and stringing of the mouth of the 20th shot. ×: Any of smoothness, unevenness and stringing of the mouth of the 20th shot. There is a problem with crab and continuous molding is not possible

4) Evaluation of Mold Contamination After 500 shots of continuous molding for 6 seconds per cycle were performed, the surface of the mold was strongly wiped with gauze, and the state of adhesion of oily substances to the gauze was evaluated. The evaluation criteria are shown below. ：: No adhesion of oily substance was observed. X: Adhesion of an oily substance is considerably observed. 5) Measurement of Elution Amount of Styrene Monomer One beverage container obtained by the injection blow molding was placed in 25 ml of n-heptane solvent at 25 ° C. for 6 hours.
It was immersed for 0 minutes, and the obtained eluate was subjected to gas chromatography mass spectrometry for quantitative analysis. The evaluation results are shown in Table 2. As is clear from Table 2, the beverage container obtained by the injection blow molding of the present invention has an extremely excellent balance between container properties and processability represented by container strength, moldability, mold contamination and processability. The amount of styrene monomer eluted into the solvent is extremely small.

[0052]

[Table 2]

[0053]

The beverage container obtained by the injection blow molding of the present invention has a low content of styrene-based low-molecular components such as styrene monomer and styrene oligomer and a low content of residual hydrocarbon solvent, and has improved container characteristics and thermal stability. Excellent, and the amount of styrene monomer eluted into the pseudo solvent is extremely small.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 25/04 C08L 51/04 51/04 91/00 91/00 B29K 25:00 // B29K 25:00 B29L 22:00 B29L 22:00 B65D 1/00 A (72) Inventor Kiyoshi Kawakami 3-13-1 Ushidori, Kurashiki-shi, Okayama Pref. Asahi Kasei Corporation (72) Inventor Hiroshi Shirai 3, Ushio, Kurashiki-shi, Okayama 13-1 Asahi Kasei Corporation F-term (reference) 3E033 BA22 BB01 FA03 GA02 4F208 AA13 AB15 AG07 AG19 AH55 AM32 LA01 LB01 LD02 LG28 4J002 AE053 BC03X BC04W BN14W EF057 EG027 EG037 AC12 AC33 AC02A AC33A BA05 DB02 DB15 DB24 GA08 4J100 AB02P BA01 CA01 DA04 JA58

Claims (3)

[Claims] 1. A rubber-modified styrene resin having a gel content of 5 to 30%, an average rubber particle diameter of 0.2 to 5 μm, and a weight average molecular weight of a matrix phase of 100,000 to 500,000,
The styrene monomer contained in the resin is 200 pp
m, the total amount of styrene dimer and trimer is 300
50 ppm of a styrene-based low molecular weight component having a molecular weight of 140 to 400 other than styrene dimer and trimer.
A beverage container obtained by subjecting a rubber-modified styrene resin having less than 0 ppm and less than 1000 ppm of a residual hydrocarbon solvent to injection blow molding. 2. The rubber-modified styrenic resin comprises 5 to 60% by weight of an impact-resistant styrenic resin (A) and 95 to 40% by weight of a styrenic resin (B). Weight average molecular weight 100,000 to 600,000, molecular weight distribution (Mw / Mn) 1.5 to 5.0, styrene monomer contained less than 100 ppm, total amount of styrene dimer and trimer less than 500 ppm, molecular weight 140 other than styrene dimer and trimer The beverage container according to claim 1, wherein the content of the styrene-based low-molecular component in the range of ~ 400 to less than 500 ppm and the residual hydrocarbon solvent contained is less than 1000 ppm. 3. The rubber-modified styrene resin contains 1.0 to 4.0% by weight of a mineral oil and 0.1 to 0.5% by weight of a higher fatty acid and a higher fatty acid metal salt. 3. The beverage container according to 2.