JPH09188728A - Modified polypropylene resin and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the above propylene resin whose extension viscosity measured in a melted state steeply increases with the increase of distortion, by melting and kneading a polypropylene resin with an aromatic vinyl monomer and a radical polymerization initiator. SOLUTION: This modified polypropylene resin is obtained by melt-kneading (A) a polypropylene resin (e.g. polypropylene homopolymer, the block copolymer of propylene with one or more other monomers such as ethylene) with (B) an aromatic vinyl monomer and (C) a radical polymerization initiator [e.g. α,α'-bis(di-t-butylperoxy-misopropyl)benzene] e.g. in an A:B:C wt. ratio of 100:(3-30):(0.1-4) at approximately 160-400 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene resin (hereinafter sometimes referred to as “modified polypropylene resin”) in which an aromatic vinyl monomer is graft-copolymerized with a polymer molecule, and a method for producing the same.

More specifically, in the present invention, the elongational viscosity measured in a molten state, which is obtained by melt-kneading a polypropylene resin, an aromatic vinyl monomer and a radical polymerization initiator, increases as the amount of strain increases. TECHNICAL FIELD The present invention relates to a rapidly increasing modified polypropylene resin and a method for producing the same.

[0003]

2. Description of the Related Art Generally, a polypropylene resin comprises a polypropylene polymer polymerized by using a Ziegler-Natta catalyst, and the polypropylene polymer usually has an isotactic linear molecular structure. It is a semi-crystalline thermoplastic polymer having.

Such polypropylene resins are excellent in heat resistance, chemical resistance, electric insulation and the like, and have processing characteristics according to the purpose by controlling the molecular weight of polymer molecules. Therefore, it has a wide range of uses such as films, fibers and molded articles of various shapes.

However, the conventional polypropylene-based resin has a remarkably low viscosity and tensile strength at the time of melting, and therefore, for example, blow molding, extrusion coating molding, foam molding, etc., which greatly deforms the resin in a molten state. It can be said that it is not suitable for the method.

As a method for solving these problems, Japanese Patent Application Laid-Open No. 62-121704 discloses a semi-crystalline polypropylene system having a linear molecular structure in a gas atmosphere adjusted to a specific oxygen concentration. A method has been proposed in which the viscosity and tensile strength of the polypropylene resin at the time of melting are increased by irradiating the resin with radiation. In the patent publication, the polypropylene-based resin modified by this method has a structure in which the polymer molecule has a long-chain branch, and the resin is used for molding methods such as blow molding and extrusion coating molding. It is described as being suitable.

The reason why the polypropylene resin modified by this method is suitable for these molding methods is that the elongational viscosity measured in the molten state of this resin is
It means that the strain increases sharply as the amount of strain increases, that is, when the resin is stretch-deformed in the molten state, the extension viscosity increases as the extension strain increases, and the elongation It is mentioned that the elongation viscosity increases sharply when it reaches the boundary.

However, when the modified polypropylene resin is modified by this method, it is possible to avoid the fact that the apparatus used is large in scale and the structure of the apparatus is complicated because of utilizing radiation. Absent. Further, in the irradiation step, in order to prevent decomposition and gelation of the propylene-based resin and to stably manufacture the product, it is necessary to strictly control the irradiation amount of the radiation and the oxygen concentration of the atmospheric gas. In addition, since it is necessary to strictly control the production conditions in this manner, it is not easy to give the target modified polypropylene resin a variation in the physical properties.

Further, Japanese Patent Application Laid-Open No. 7-118545 discloses a multi-phase structure thermoplastic resin containing as one component a resin which exhibits a non-linear extensional viscosity when extended at a constant strain rate. It is also disclosed that this resin is suitable for a molding method involving large deformation.

However, these techniques relate to improvements in the molding method of multiphase resins, and disclose the use of modified polyethylene as one component of the above multiphase resins. It is a thing. Also, as a modification method thereof, polyethylene, a specific monomer and a specific initiator are suspended in an aqueous solvent, and then the monomer is graft-copolymerized with a polymer molecule of polyethylene in the aqueous solvent. Only the method of making is given. That is, in this method, after the graft copolymerization, it is necessary to remove the above-mentioned aqueous solvent and the like, and further it is necessary to carry out the graft copolymerization in a closed system or the like, which makes continuous production impossible. It has the drawback of.

[0011]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a modified polypropylene resin whose elongational viscosity measured in a molten state by a simple method and an easy method rapidly increases as the amount of strain increases. To provide.

[0012]

Means for Solving the Problems The present invention is obtained by melt-kneading a polypropylene resin, an aromatic vinyl monomer and a radical polymerization initiator, and the elongational viscosity measured in a molten state is
The present invention relates to a method for producing a modified polypropylene resin that sharply increases as the amount of strain increases.

The present invention also relates to a modified polypropylene resin obtained by the above-mentioned manufacturing method.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The modified polypropylene resin of the present invention is obtained by graft-copolymerizing an aromatic vinyl monomer to a polymer molecule of the polypropylene resin, and the extensional viscosity measured in a molten state has a strain amount of It has the property of increasing rapidly as it increases, and therefore has high viscosity and tensile strength when melted, and drawdown does not easily occur even when it is subjected to a molding method that greatly deforms the molten resin. The inventors have found that the workability is remarkably improved, and completed the present invention.

Examples of the molding method for greatly deforming the molten resin include blow molding, extrusion coating molding, foam molding, vacuum molding and pressure molding.

In the present invention, the characteristic that the extensional viscosity measured in the molten state sharply rises as the amount of strain increases (hereinafter sometimes referred to as "specific extensional viscosity characteristic") will be described below.

As a method for evaluating this characteristic, for example, a strand-shaped resin molded body having a diameter of about 3 mm is used as a sample, and both ends of this sample are sandwiched by rotary clamps, and the temperature at which this sample is completely melted (for example, a book In the case of the modified polypropylene resin in the invention, the temperature of this sample is usually maintained at about 180 ° C., this sample is elongated at a constant strain rate, and the stress generated between chucks is measured with time. There is a method of determining the extensional viscosity from the relationship between the cross-sectional area of the sample and the cross-sectional area at that time.

That is, the extensional viscosity is calculated by the following formula:

[0019]

[Equation 1]

## EQU1 ## The elongational viscosity is plotted over time. At this time, the extensional viscosity gradually increases as the measurement time elapses (as the strain amount increases), and the increase rate of the extensional viscosity increases from a certain measurement time (at a certain strain amount) until then. It can be said that those that rapidly increase have specific elongational viscosity characteristics.

Further, in a curve showing the relationship between the measurement time and the extension viscosity, which is obtained by taking the logarithm of the measurement time on the horizontal axis and the logarithm of the extension viscosity on the vertical axis, the extension viscosity at the initial stage of measurement of the curve is the extension time. The slope of the straight line drawn from the part where the extensional viscosity rises most rapidly with the elapse of the measurement time is 1.5 times or more the slope of the straight line drawn from the part that rises relatively slowly with the passage of It is preferable that it is more than double. On the other hand, although the upper limit of this value is not limited, normally, according to the method for producing a modified polypropylene resin of the present invention, a modified polypropylene resin having this value up to about 20 times can be produced.

The slope of each straight line drawn from the above curve is obtained by the following formula: Δ (log η _e ) / Δ (logt) (where η _e is extensional viscosity (poise), t
Represents the measurement time (seconds).

Further, the modified polypropylene resin having such a specific extensional viscosity characteristic is usually measured such that the extensional viscosity becomes low as the measurement time elapses (increase in strain amount) in the extensional viscosity measurement. There are no regions, and the measurement sample eventually elastically breaks as if the rubber had broken.

On the other hand, in the case of a normal linear polypropylene resin, the elongational viscosity generally increases with the lapse of measurement time (increase in strain amount), but a drastic increase in elongational viscosity is hardly observed. . Further, in many cases, a phenomenon in which the elongational viscosity decreases immediately before the measurement sample breaks is observed, and subsequently the measurement sample breaks plastically.

FIG. 1 shows the relationship between the extensional viscosity of the modified polypropylene resin and the measuring time in Example 1 described later. This figure shows a modified polypropylene resin with a diameter of 3 m.
m into a cylindrical rod with a length of 180 mm,
It shows the relationship between the elongation viscosity (logarithm) and the measurement time (logarithm) when elongated at a strain rate of 0.05 / sec under ° C.

In FIG. 1, a straight line drawn from the flat portion (the portion where the extensional viscosity increases relatively slowly as the measurement time elapses) of the initial curve of the curve showing the relationship between the extensional viscosity and the measurement time is shown. From the relationship between the slope and the slope of the straight line drawn from the part where the extensional viscosity of this curve rises most rapidly with the passage of measurement time (the values of the respective slopes are shown in () in the figure), It can be seen that the elongational viscosity sharply increases as the strain rate increases.

The measurement temperature at this time is not limited to 180 ° C., but is not lower than the temperature at which the polypropylene resin is substantially melted and lower than the temperature at which the polypropylene resin starts thermal decomposition. It may be arbitrarily selected and is usually preferably set in the range of 170 to 250 ° C. The strain rate condition is generally 0.01 to 0.5.
It is preferable to set in the range of / second.

If the specific elongational viscosity characteristic is a resin which is recognized under any one measuring condition within the range of the measuring temperature and within the range of the strain rate condition, the measurement is usually carried out. This particular extensional viscosity characteristic is observed when measured under measuring conditions within all ranges of temperature and strain rate conditions.

The modified polypropylene resin of the present invention is obtained by kneading the polypropylene resin before graft copolymerization, the aromatic vinyl monomer and the radical polymerization initiator at a temperature at which the resin melts. .

Examples of the polypropylene resin (polypropylene resin before graft copolymerization) include propylene homopolymers, block copolymers of propylene and other monomers, and random copolymers of propylene and other monomers. Examples include crystalline polymers such as copolymers, which have high rigidity,
From the viewpoint of low cost, the polypropylene homopolymer is preferable, and from the viewpoint of high rigidity and high impact resistance, a block copolymer of the propylene and another monomer is preferable. If the polypropylene resin before graft copolymerization is a block copolymer of propylene and other monomers or a random copolymer of propylene and other monomers, the high crystalline characteristic of polypropylene resin From the viewpoint of maintaining the properties, high rigidity and good chemical resistance, the propylene monomer component contained is preferably 75% by weight or more, and more preferably 90% by weight or more of the whole.

In the polypropylene resin before graft copolymerization, the other monomer copolymerizable with propylene is a monomer composed of ethylene, α-olefin, cyclic olefin, diene monomer and vinyl monomer. One or more monomers selected from the group of monomers may be mentioned. Further, as the monomer, ethylene, α-olefin or diene-based monomer is preferable because it is easily copolymerized with propylene and is inexpensive.

Examples of the above-mentioned α-olefin copolymerizable with propylene include butene-1, isobutene, pentene-1,3-methyl-butene-1, hexene-1,3-hexene.
Methyl-pentene-1, 4-methyl-pentene-1,
Α-olefins having 4 to 12 carbon atoms, such as 3,4-dimethyl-butene-1, heptene-1, 3-methyl-hexene-1, octene-1, and decene-1. Examples of the cyclic olefin copolymerizable with propylene include cyclopentene, norbornene, 1,4.
5,8-Dimethano-1,2,3,4,4a, 8,8a-
6-octahydronaphthalene and the like. Also,
Examples of the diene-based monomer copolymerizable with propylene include 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-1,4-hexadiene, 7- Methyl-1,6-octadiene and the like can be mentioned. Further, examples of the vinyl monomer copolymerizable with the above-mentioned propylene include vinyl chloride,
Examples thereof include vinylidene chloride, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, ethyl acrylate, butyl acrylate, methyl methacrylate, maleic anhydride, styrene, methylstyrene and divinylbenzene.

Of these monomers, ethylene or butene-1 is more preferable because it is inexpensive.

The molecular weight (weight average molecular weight) of the polypropylene resin before the graft copolymerization is preferably in the range of 50,000 to 2,000,000 from the viewpoint of easy industrial availability, and is inexpensive. From 100,000 to 100
More preferably, it is in the range of 10,000.

The polypropylene resin before graft copolymerization has a melt index of 0.01 to 8 at 230 ° C.
Those in the range of g / 10 minutes are preferable. When the melt index is larger than the above range, the melt viscosity of the modified polypropylene resin tends to be too low, and thus the specific extensional viscosity characteristics tend not to be sufficiently obtained, while when it is smaller than the above range, Since the melt viscosity becomes too high, the moldability tends to be insufficient.

It should be noted that a resin obtained by blending resins having different melt indexes in the form of pellets or powder, or a mixture obtained by melt-kneading these with an extruder or the like may be used as the polypropylene resin before modification. In this case, It is preferable that the melt index of the blended product or the melt-kneaded product is within the above range for the same reason as above.

If necessary, other resins or rubbers may be added to the above polypropylene resin before graft copolymerization within a range not impairing the effects of the present invention. Examples of the other resin or rubber include polyethylene; polybutene-1, polyisobutene, polypentene-
1, poly-α-olefins such as polymethylpentene-1; ethylene / propylene copolymers having a propylene content of less than 75% by weight, ethylene / butene-1 copolymers, propylene having a propylene content of less than 75% by weight / Ethylene or α-olefin / α such as butene-1 copolymer
-Olefin copolymer; propylene content of 75% by weight
Less than ethylene / propylene / 5-ethylidene-2-norbornene copolymer or other ethylene or α-olefin / α-olefin / diene monomer copolymer; ethylene / vinyl chloride copolymer, ethylene / vinylidene chloride copolymer Polymer, ethylene / acrylonitrile copolymer, ethylene / methacrylonitrile copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylamide copolymer, ethylene / methacrylamide copolymer, ethylene / acrylic acid copolymer, Ethylene / methacrylic acid copolymer, ethylene / maleic acid copolymer, ethylene / ethyl acrylate copolymer, ethylene / butyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / maleic anhydride copolymer Coalescence, ethylene / acrylic acid metal salt copolymer, ethylene / meta Ethylene or α-olefin / vinyl monomer copolymers such as acrylic acid metal salt copolymers, ethylene / styrene copolymers, ethylene / methylstyrene copolymers, ethylene / divinylbenzene copolymers; polybutadiene, polyisoprene Polydiene-based copolymers such as; styrene / butadiene random copolymers and other vinyl monomers / diene-based monomer random copolymers; styrene / butadiene / styrene block copolymers and other vinyl monomers / diene-based copolymers Monomer / Vinyl monomer block copolymer; Hydrogenation (styrene / butadiene random copolymer)
Hydrogenation (vinyl monomer / diene monomer random copolymer); hydrogenation (styrene / butadiene / styrene block copolymer) hydrogenation (vinyl monomer / diene monomer / Vinyl monomer block copolymer); acrylonitrile / butadiene / styrene graft copolymer,
Vinyl monomer / diene monomer / vinyl monomer graft copolymer such as methyl methacrylate / butadiene / styrene graft copolymer; polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyvinyl acetate, polyacrylic Vinyl polymers such as ethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polystyrene; vinyl chloride / acrylonitrile copolymer, vinyl chloride / vinyl acetate copolymer, acrylonitrile / styrene copolymer, methyl methacrylate / styrene copolymer Examples thereof include vinyl copolymers such as polymers.

The addition amount of these other resins or rubbers to the polypropylene resin before graft copolymerization varies depending on the type of the resin or the type of rubber, and is within the range not impairing the effects of the present invention as described above. Although it is good, it is usually preferably about 25% by weight or less.

Further, if necessary, the polypropylene resin before the graft copolymerization may include an antioxidant, a metal deactivator, a phosphorus processing stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, an optical brightener, Stabilizers such as metal soaps and antacid adsorbents,
Alternatively, a crosslinking agent, a chain transfer agent, a nucleating agent, a lubricant, a plasticizer, a filler, a reinforcing material, a pigment, a dye, a flame retardant, an additive such as an antistatic agent is added within a range not impairing the effects of the present invention. Good.

The polypropylene resin before graft copolymerization (which may include various additives) may be in the form of particles or pellets, and the size and shape thereof are It is not particularly limited.

When the above-mentioned additive material (other resin, rubber, stabilizer and / or additive) is used,
This additive material may be added in advance to the polypropylene resin before the graft copolymerization, or may be added when the polypropylene resin is melted, and after the graft copolymerization It may be added by an appropriate method.

Examples of the aromatic vinyl monomer include styrene, alkyl-substituted styrene, halogenated styrene, nitrated styrene, divinylbenzene, isopropenylstyrene, and the like. Specifically, for example, styrene; o-methyl. Styrene, m-methylstyrene, p
-Methylstyrene such as methylstyrene, α-methylstyrene, β-methylstyrene, dimethylstyrene and trimethylstyrene; α-chlorostyrene, β-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-
Chlorostyrenes such as chlorostyrene, dichlorostyrene and trichlorostyrene; bromostyrenes such as o-bromostyrene, m-bromostyrene, p-bromostyrene, dibromostyrene and tribromostyrene; o-fluorostyrene, m-fluorostyrene, p -Fluorostyrene such as fluorostyrene, difluorostyrene and trifluorostyrene; nitrostyrene such as o-nitrostyrene, m-nitrostyrene, p-nitrostyrene, dinitrostyrene and trinitrostyrene; o-hydroxystyrene, m-hydroxystyrene , Vinylphenol such as p-hydroxystyrene, dihydroxystyrene and trihydroxystyrene; divinylbenzene such as o-divinylbenzene, m-divinylbenzene and p-divinylbenzene. o- diisopropenylbenzene, m- diisopropenylbenzene, one or two or more of such isopropenyl styrene such as p- diisopropenylbenzene and the like. Of these, styrene,
α-Methylstyrene, methylstyrene such as p-methylstyrene, divinylbenzene or a mixture of divinylbenzene isomers is preferable because it is inexpensive.

In the modified polypropylene resin of the present invention, one or more aromatic vinyl graft chains composed of the aromatic vinyl monomer are grafted on average per modified polypropylene copolymer molecule. It is a thing.

The aromatic vinyl graft chain is preferably composed of one kind or two or more kinds of the aromatic vinyl monomer, but the aromatic vinyl monomer and the aromatic vinyl monomer are copolymerized. It may be formed by copolymerization with other possible vinyl monomers.

Other vinyl monomers copolymerizable with the aromatic vinyl monomer include, for example, vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile,
Acrylamide, methacrylamide, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, maleic anhydride,
Acrylic acid metal salts, methacrylic acid metal salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, glycyl acrylate; methyl methacrylate, ethyl methacrylate, Butyl methacrylate,
Examples thereof include methacrylic acid esters such as 2-ethylhexyl methacrylate, stearyl methacrylate, and glycyl methacrylate.

When the aromatic vinyl graft chain contains an aromatic vinyl monomer component and another vinyl monomer component copolymerizable with the aromatic vinyl monomer, the aromatic vinyl monomer Other vinyl monomer components that can be copolymerized with
It is preferably less than 100 parts by weight on average with respect to 100 parts by weight of the aromatic vinyl monomer component, and 7 on average.
It is more preferably less than 5 parts by weight. When the other vinyl monomer component that can be copolymerized with the aromatic vinyl monomer in the aromatic vinyl graft chain exceeds the above range, good results are obtained when the strand of the modified polypropylene resin is extruded. In some cases, strands cannot be formed and suitable pellets cannot be obtained.

The amount of the aromatic vinyl monomer to be melt-kneaded is the polypropylene resin 1 before graft copolymerization.
The amount is preferably 3 to 50 parts by weight, more preferably 3 to 30 parts by weight, relative to 00 parts by weight. If the amount of the vinyl monomer is less than the above range, the modified polypropylene resin of interest may not have sufficient specific extensional viscosity characteristics, while if it exceeds the above range, The heat resistance and rigidity, which are characteristics of polypropylene resins, tend to be impaired.

The radical polymerization initiator is generally a peroxide or an azo compound. In order for the graft copolymerization reaction to occur between the polymer molecule of the polypropylene resin and the vinyl monomer, or between the polymer molecule of the polypropylene resin and the polymer molecule of the polypropylene resin, a compound having a so-called hydrogen abstraction ability. Are generally required, and are generally ketone peroxides such as methyl ethyl ketone peroxide and methyl acetoacetate peroxide; 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis. Peroxyketals such as (t-butylperoxy) cyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate and 2,2-bis (t-butylperoxy) butane; permethane hydroper Oxide, 1,1,3,3-tetramethylbutyl hydrate Hydroperoxides such as peroxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide; dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, α, α′-bis (T-butylperoxy-m-isopropyl) benzene, t-butylcumyl peroxide, di-t-butylperoxide, 2,
Dialkyl peroxide such as 5-dimethyl-2,5-di (t-butylperoxy) hexyne-3; diacyl peroxide such as benzoyl peroxide; di (3-methyl-3-methoxybutyl) peroxydicarbonate, Peroxydicarbonates such as di-2-methoxybutylperoxydicarbonate; t-butylperoxyoctate, t-butylperoxyisobutyrate, t-butylperoxylaurate, t-butylperoxy-3, 5,5-trimethylhexanoate, t
-Butyl peroxyisopropyl carbonate, 2.5
-Organic peroxides such as peroxyesters such as dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate can give. Among these, those having particularly high hydrogen abstraction ability are preferable, and examples thereof include 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and 1,1-bis (t-butylperoxy) cyclohexane. , N-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane and other peroxyketals; dicumyl peroxide, 2,5-dimethyl-2 , 5-di (t-butylperoxy) hexane, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, t-butylcumyl peroxide, di-t-butylperoxide,
Dialkyl peroxides such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3; diacyl peroxides such as benzoyl peroxide; t-butylperoxyoctate, t-butylperoxyiso Butyrate, t-butylperoxylaurate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di (benzoylper) (Oxy) hexane, t-butylperoxyacetate, t-butylperoxybenzoate, peroxyesters such as di-t-butylperoxyisophthalate, and the like, or one or more of them.

The amount of the radical polymerization initiator added is based on 100 parts by weight of the polypropylene resin before graft copolymerization, because the modified polypropylene resin is easily elastically deformed when melted and is economical. , 0.0
It is preferably in the range of 1 to 8 parts by weight,
More preferably, it is in the range of 4 parts by weight.

The order and method of mixing and melt-kneading these modified polypropylene resin, aromatic vinyl monomer, radical polymerization initiator and other added materials are not particularly limited. A polypropylene resin before polymerization, an aromatic vinyl monomer, a radical polymerization initiator and other additives which are optionally added may be mixed and then melt-kneaded, or a polypropylene resin before graft copolymerization After melt-kneading, the aromatic vinyl monomer, the radical polymerization initiator, and other additives to be added if necessary may be mixed simultaneously or separately, collectively or in a divided manner.

The heating temperature at the time of melt-kneading varies depending on the type of resin, etc., but it is usually from 160 to 400 ° C. The polypropylene-based resin before graft copolymerization is sufficiently melted and is not thermally decomposed, It is preferable in that the above graft copolymerization reaction sufficiently occurs. The melt-kneading time (time after mixing the radical polymerization initiator and the aromatic vinyl monomer) is generally 30 seconds to 60 minutes.

As the melt-kneading device, a kneader such as a roll, a co-kneader, a Banbury mixer, a Brabender, a single-screw extruder or a twin-screw extruder, a twin-screw surface renewing machine, a two-screw multi-disc device. Examples of the apparatus include a horizontal stirrer such as or a vertical stirrer such as a double helical ribbon stirrer, which can heat a polymer material to an appropriate temperature and knead while applying an appropriate shear stress. Of these, a single-screw or twin-screw extruder is particularly preferable from the viewpoint of productivity. The melt-kneading may be repeated a plurality of times in order to mix the respective materials sufficiently uniformly.

The modified polypropylene resin of the present invention can be suitably applied to a molding method such as blow molding, extrusion coating molding, foam molding, vacuum molding, and pressure molding, which greatly deforms a resin in a molten state. it can. Examples of molded articles using such a molding method include:
Examples include blow bottles, foam sheets, foam boards, and the like.

[0054]

EXAMPLES Next, the present invention will be described in detail based on examples, but the present invention is not limited to such examples.

In the following examples and comparative examples, the extensional viscosity of the modified polypropylene resin or polypropylene resin (polypropylene resin not graft-copolymerized) measured in the molten state and the measurement time (strain amount) The relationship with and was measured by the following method.

The modified polypropylene resin or the polypropylene resin pellets were filled in a capillograph provided with an orifice having a diameter of 3 mm, melted at 200 ° C., and then extruded to form a strand-shaped sample having a length of about 180 mm. . Using this sample, the elongation viscosity and the measurement time (strain amount) at 180 ° C. and a strain rate of 0.05 / sec were measured using a Melten Rheometer manufactured by Toyo Seiki Co., Ltd.
To measure the relationship with. At this time, the elongational viscosity is determined by dividing the stress by the cross-sectional area of the sample measured by the charge coupled device (CCD). That is, the extensional viscosity is given by the following equation:

[0057]

[Equation 2]

## EQU5 ##

For example, in FIG. 1 (which shows the relationship between the extensional viscosity of the modified polypropylene resin and the measurement time in Example 1 described later), the extensional viscosity rises with a gentle slope from immediately after the start of measurement to about 10 seconds. However, since then, the extensional viscosity has risen sharply. The slope of the flat portion of the initial curve of the measurement of the slope of the portion where the extension viscosity is rapidly increasing (the slope of the straight line drawn from the portion where the extension viscosity is increasing most rapidly as the measurement time elapses) ( A ratio (hereinafter, also referred to as a “specific elongation viscosity ratio”) to a slope of a straight line drawn from a portion where the elongation viscosity increases relatively slowly as the measurement time elapses is obtained.

Example 1 Polypropylene homopolymer (Mitsui Petrochemical Industry Co., Ltd.)
Made, homo polypropylene powder B200P, 230 ℃
Melt index 0.5 g / 10 minutes), styrene (manufactured by Wako Pure Chemical Industries, Ltd., special grade) 20 parts by weight, and α, α'-bis (di-t-butylperoxy-).
3.5 parts by weight of m-isopropyl) benzene (manufactured by NOF CORPORATION, Perbutyl P, 1-minute half-life temperature 175 ° C.) and IRGANOX B225 (product name, as a stabilizer
0.2 parts by weight of Ciba-Geigy Co., Ltd.) and 0.1 parts by weight of calcium stearate are blended,
It was supplied to a twin-screw extruder (LABOTEX) manufactured by Japan Steel Works, Ltd. to obtain a modified polypropylene resin.

The twin-screw extruder was of the same-direction, twin-screw type, and had a cylinder hole diameter of 32 mmφ and a maximum screw effective length (L / D) of 25.5. Set the temperature of the cylinder of this twin-screw extruder to 200 ° C,
The feed temperature was set to 160 ° C. and heated, and the rotation speed of the screw was set to 100 rpm for each shaft.

FIG. 1 shows the relationship between the elongational viscosity of the obtained modified polypropylene resin measured in the molten state and the measurement time (strain amount). The specific elongational viscosity ratio of this modified polypropylene resin was 8.9.

Example 2 The amount of styrene was changed from 20 parts by weight to 10 parts by weight, and α,
Modified polypropylene resin in the same manner as in Example 1 except that the amount of α'-bis (di-t-butylperoxy-m-isopropyl) benzene was changed from 3.5 parts by weight to 1.75 parts by weight. I got it.

FIG. 2 shows the relationship between the elongation viscosity measured in the molten state of the obtained modified polypropylene resin and the measurement time (strain amount). The specific elongational viscosity ratio of the modified polypropylene resin was 4.0.

Example 3 The same as Example 1 except that the amount of α, α′-bis (di-t-butylperoxy-m-isopropyl) benzene was changed from 3.5 parts by weight to 1 part by weight. , Modified polypropylene resin was obtained.

FIG. 3 shows the relationship between the elongational viscosity of the obtained modified polypropylene resin measured in the molten state and the measurement time (strain amount). The specific elongation viscosity ratio of this modified polypropylene resin was 3.4.

Comparative Example 1 Polypropylene homopolymer (Sumitomo Chemical Co., Ltd., Nobrene H501, melt index 3.5 g / 10 minutes at 230 ° C.) The relationship between extensional viscosity and strain amount measured in the molten state I asked. FIG. 4 shows the results.

Comparative Example 2 The amount of styrene was changed from 20 parts by weight to 2 parts by weight, and α, α'-
Bis (di-t-butylperoxy-m-isopropyl)
A modified polypropylene resin was obtained in the same manner as in Example 1 except that the amount of benzene was changed from 3.5 parts by weight to 0.35 parts by weight.

FIG. 5 shows the relationship between the elongation viscosity of the obtained modified polypropylene resin measured in the molten state and the measurement time (strain amount). With respect to this modified polypropylene-based resin, a sharp increase in elongational viscosity was not observed even if the amount of strain increased.

[0070]

The modified polypropylene resin of the present invention is
It has a high viscosity and a high tensile strength when melted, and because of this, drawdown is less likely to occur. Therefore, the modified polypropylene resin of the present invention can be suitably used as a material for a molded article using a molding method such as blow molding, extrusion coating molding, and foam molding, and when these molding methods are used. However, the molding conditions can be selected from a wide range of conditions.

The modified polypropylene resin is
It is a modified polypropylene resin and has suitable chemical resistance, impact resistance, heat resistance, electrical insulation and the like.

[Brief description of the drawings]

FIG. 1 shows the relationship between extensional viscosity measured in a molten state of a modified polypropylene resin in Example 1 and measurement time (strain amount).

FIG. 2 shows the relationship between the extensional viscosity measured in the molten state of the modified polypropylene resin and the measurement time (strain amount) in Example 2.

FIG. 3 shows the relationship between the extensional viscosity measured in the molten state of the modified polypropylene resin and the measurement time (strain amount) in Example 3.

FIG. 4 shows the relationship between the extensional viscosity measured in the molten state of the polypropylene resin and the measurement time (strain amount) in Comparative Example 1.

FIG. 5 shows the relationship between the extensional viscosity measured in the molten state of the modified polypropylene resin in Comparative Example 2 and the measurement time (strain amount).

Claims (2)

[Claims] 1. A modified polypropylene obtained by melt-kneading a polypropylene-based resin, an aromatic vinyl monomer and a radical polymerization initiator, in which the elongational viscosity measured in a molten state sharply increases as the amount of strain increases. Resin-based manufacturing method. 2. A modified polypropylene resin obtained by the method according to claim 1.