Method for producing modified amorphous polypropylene

Abstract

To provide a method that can produce modified amorphous polypropylene with high efficiency in grafting and suppressed changes in molecular weight, without causing handling trouble even when graft-polymerizing amorphous polypropylene in a melt kneader.SOLUTION: A method for producing modified amorphous polypropylene includes melting and kneading following ingredients at 130-180°C: amorphous polypropylene, an ethylenic unsaturated monomer with a carboxyl group or an acid anhydride group, an organic peroxide, an electron-donating polyfunctional ethylenic unsaturated monomer, and an electron-donating chain transfer agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing modified amorphous polypropylene. [Background technology]

[0002] Amorphous polypropylene is a safe, non-polluting, highly heat-resistant adhesive resin with excellent compatibility and adhesion to general-purpose crystalline polypropylene, and is used in various fields such as hot-melt adhesives for disposable diapers. However, due to its low polarity, it has the disadvantage of poor adhesion to other materials (e.g., metal or inorganic materials, or plastic materials other than polypropylene). To solve this problem, modified amorphous polypropylene has been produced by graft polymerization of polar monomers onto amorphous polypropylene. However, in conventional manufacturing methods, as the grafting efficiency of polar monomers increases, molecular weight decreases due to the decomposition of amorphous polypropylene, leading to a decrease in heat resistance. On the other hand, there was also the problem that the molecular weight increased due to the crosslinking reaction of amorphous polypropylene, resulting in an excessive increase in melt viscosity.

[0003] Various manufacturing methods have been reported to solve the aforementioned problems. For example, Patent Document 1 addresses the problem that when vinyl monomers such as divinylbenzene are used as crosslinking aids during graft polymerization of polyolefins, graft efficiency is improved, but the decomposition and crosslinking of polyolefins cannot be effectively prevented. To solve this problem, it discloses a method of using α-methylstyrene dimer instead of divinylbenzene.

[0004] Similarly, Patent Document 2 discloses a method for using α-methylstyrene dimer as a chain transfer agent in graft polymerization for the purpose of improving graft efficiency and controlling molecular weight. Patent Document 3 also discloses a method for using α-methylstyrene dimer for the purpose of preventing the decomposition and crosslinking of polyolefins during graft polymerization.

[0005] Incidentally, graft polymerization of polypropylene can be carried out by solvent methods, which involve reactions in a solvent, and melt kneading methods, which involve reactions in a kneader. For example, Patent Document 4 discloses graft polymerization of a propylene polymer in the presence of a predetermined solvent. On the other hand, Patent Document 5 discloses graft polymerization of crystalline polypropylene in a melt kneader. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-172459 [Patent Document 2] Japanese Patent Publication No. 155413 / 1983 [Patent Document 3] Japanese Patent Application Publication No. 11-236421 [Patent Document 4] Patent No. 5002128 [Patent Document 5] Japanese Patent Publication No. 2002-234919 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] According to Patent Documents 1-3, it can be said that by using chain transfer agents such as α-methylstyrene dimer instead of vinyl monomers such as divinylbenzene in graft polymerization, it is possible to improve graft efficiency and control molecular weight. However, there is still room for improvement in these areas.

[0008] Furthermore, while Patent Document 5 describes graft polymerization of crystalline polypropylene in a melt kneader, it is not easy to use amorphous polypropylene instead of crystalline polypropylene. In other words, amorphous polypropylene has a low softening point, and when a melt kneader is used as in Patent Document 5, in addition to the inherently low softening point of amorphous polypropylene, the decrease in molecular weight due to the decomposition of polypropylene during graft polymerization results in very high fluidity of the polypropylene, causing significant problems in handling.

[0009] Therefore, the present invention aims to provide a method for producing modified amorphous polypropylene without handling problems when amorphous polypropylene is graft polymerized in a melt kneader, and with high graft efficiency and suppressed molecular weight change. [Means for solving the problem]

[0010] As a result of diligent research by the present inventors, it has been found that when graft polymerizing amorphous polypropylene in a melt kneader, by using a combination of an electron-donating polyfunctional ethylenically unsaturated monomer and an electron-donating chain transfer agent in addition to the modifiers and organic peroxides commonly used, and by melt kneading at a lower temperature than conventional methods, modified amorphous polypropylene can be obtained with high graft efficiency and suppressed molecular weight change, and problems in handling caused by the decrease in molecular weight of amorphous polypropylene can be avoided.

[0011] The present invention includes, for example, the following embodiments. [1] Amorphous polypropylene and An ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group, Organic peroxides and, Electron-donating polyfunctional ethylenically unsaturated monomers, Electron-donating chain transfer agent, This includes melting and kneading at a temperature of 130-180°C. A method for producing modified amorphous polypropylene. [2] The production method according to [1], wherein the softening point of the amorphous polypropylene is 130 to 180°C. [3] The production method according to [1] or [2], wherein the weight average molecular weight of the amorphous polypropylene is 5,000 to 500,000. [4] The production method according to any one of [1] to [3], wherein the melt viscosity of the amorphous polypropylene at 190°C is 0.01 to 50 Pa·s. [5] The production method according to any one of [1] to [4], wherein the ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group contains at least one selected from the group consisting of methacrylic acid, acrylic acid, and maleic anhydride. [6] The production method according to any one of [1] to [5], wherein the ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group contains methacrylic acid. [7] The production method according to any one of [1] to [6], wherein the electron-donating polyfunctional ethylenically unsaturated monomer has two or more vinyl groups or two or more allyl groups and has an aromatic ring or an isocyanuric ring. [8] The production method according to any one of [1] to [7], wherein the electron-donating polyfunctional ethylenically unsaturated monomer contains at least one selected from the group consisting of divinylbenzene and triallyl isocyanurate. [9] The electron-donating chain transfer agent is represented by the following formula (1):

Chemical formula

[10] The production method according to any one of [1] to [9], wherein the electron-donating chain transfer agent contains an α-methylstyrene dimer.

[11] The electron-donating chain transfer agent is represented by the following formula (2): [Chemical formula] [In the formula, R 5 and R 6 are each independently hydrogen or a hydroxyl group, or R 5 and R 6 may together with the carbon atom to which they are attached form a benzene ring] The production method according to any one of [1] to

[10] , comprising a compound represented by

[12] The production method according to any one of [1] to

[11] , wherein the temperature of the melt-kneading is not less than [softening point of the amorphous polypropylene - 10°C] and not more than [boiling point of the ethylenically unsaturated monomer having a carboxyl group or acid anhydride group + 20°C]. [Advantages of the Invention]

[0012] According to the present invention, there is provided a method capable of producing a modified amorphous polypropylene without causing problems in handling even when the amorphous polypropylene is subjected to graft polymerization in a melt-kneader, and with high graft efficiency and suppressed molecular weight change. [Modes for Carrying Out the Invention]

[0013] Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof.

[0014] [Production Method of Modified Amorphous Polypropylene] One embodiment of the present invention relates to a method for producing modified amorphous polypropylene, comprising melt-kneading amorphous polypropylene, an ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group (hereinafter also referred to as "polar monomer"), an organic peroxide, an electron-donating polyfunctional ethylenically unsaturated monomer (hereinafter also referred to as "polyfunctional monomer"), and an electron-donating chain transfer agent (hereinafter also simply referred to as "chain transfer agent") at a temperature of 130 to 180°C.

[0015] In this specification, "modified amorphous polypropylene" means amorphous polypropylene grafted with polar monomers.

[0016] According to the manufacturing method of this embodiment, modified amorphous polypropylene can be produced with high graft efficiency and suppressed molecular weight change (particularly suppressed molecular weight reduction). Furthermore, by suppressing the molecular weight reduction, it is possible to avoid handling problems even when amorphous polypropylene with a low softening point is graft polymerized in a melt kneader. The reasons for obtaining such effects are assumed to be as follows, but the present invention is not limited in any way by the reasons assumed below.

[0017] [Assumed reason] In typical polypropylene graft polymerization, radicals generated from organic peroxides abstract hydrogen atoms from polypropylene (particularly those bonded to tertiary carbons). The resulting polypropylene radicals then react with a modifying agent (graft polymerization) to obtain modified polypropylene. However, before reacting with the modifying agent, the polypropylene radicals may undergo β-cleavage to self-stabilize their main chain, which can reduce the molecular weight of the polypropylene.

[0018] In graft polymerization, when polyfunctional monomers are used in combination, the polyfunctional monomers bind to polypropylene radicals, and these bound polyfunctional monomers then further bind to a modifying agent, resulting in modified polypropylene. However, the polymerization of the modifying agent on the bound polyfunctional monomers increases the molecular weight of the modified polypropylene, leading to increased viscosity.

[0019] Furthermore, when a chain transfer agent is used in graft polymerization, the chain transfer agent binds to polypropylene radicals, and these bound chain transfer agents then bind to a modifying agent, resulting in modified polypropylene. However, in the reaction between the chain transfer agent and the polypropylene radical, new radicals generated from the chain transfer agent can cause polymers of the modifying agent that are not grafted onto the polypropylene to form.

[0020] On the other hand, in the manufacturing method of this embodiment, by using a combination of a polyfunctional monomer and a chain transfer agent in graft polymerization, the polyfunctional monomer and / or the chain transfer agent bind to the polypropylene radical before β-cleavage occurs, thereby preventing the occurrence of β-cleavage. This is expected to suppress the decrease in the molecular weight of polypropylene. Furthermore, the polyfunctional monomers bonded to polypropylene not only bind to the modifying agent, but also to polymers of the modifying agent generated by radicals derived from the chain transfer agent, thereby reducing the amount of modifying agent that is not grafted. This is expected to improve the grafting efficiency of polypropylene.

[0021] [Amorphous polypropylene] In the manufacturing method according to this embodiment, amorphous polypropylene is used. Because amorphous polypropylene has a low softening point, graft polymerization in a melt kneader has generally been difficult from the viewpoint of handling. However, in the manufacturing method according to this embodiment, it is possible to use amorphous polypropylene, which has been difficult to use until now.

[0022] In this specification, "amorphous" means that, in the measurement of the heat of crystallization as defined in JIS K 7122:2012, the degree of crystallinity determined from the heat of crystallization when cooled at a cooling rate of 10°C / min is 20% or less.

[0023] The softening point of amorphous polypropylene is not particularly limited, but examples include 130-180°C, 140-175°C, or 150-170°C. Amorphous polypropylene having such a softening point is difficult to use in conventional melt-mixing methods, and is therefore suitable for use in this embodiment. The softening point of amorphous polypropylene is measured using the ring-and-ball method based on the "Test Method for Softening Point of Hot Melt Adhesives" specified in JIS K6863:1994.

[0024] The weight-average molecular weight of amorphous polypropylene is not particularly limited, but is preferably 5,000 to 500,000, more preferably 10,000 to 200,000, and even more preferably 20,000 to 100,000. The weight-average molecular weight of amorphous polypropylene is measured by high-temperature size exclusion chromatography as specified in JIS K 7252-4:2016.

[0025] The melt viscosity of amorphous polypropylene is not particularly limited, but for example, it is preferably 0.01 to 50 Pa·s at 190°C, and more preferably 0.1 to 30 Pa·s. Amorphous polypropylene having such a melt viscosity tends to have a low softening point, and is therefore suitable for use in this embodiment. The melt viscosity of amorphous polypropylene can be measured according to the method described in the examples.

[0026] Amorphous polypropylene may be a homopolymer composed solely of propylene monomers, or it may be a copolymer further containing other monomers. If amorphous polypropylene is a copolymer, the copolymer may be a random copolymer or a block copolymer.

[0027] The amount of propylene monomer, based on all monomers constituting amorphous polypropylene, is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol%. The amount of propylene monomer can be measured using a nuclear magnetic resonance (NMR) spectrometer.

[0028] When amorphous polypropylene is a copolymer, the other monomers are not particularly limited, but examples include olefins other than propylene, specifically olefins having 2 or 4 to 8 carbon atoms.

[0029] Amorphous polypropylene may be used alone or in combination of two or more types.

[0030] [Ethylene-unsaturated monomers (polar monomers) having a carboxyl group or an acid anhydride group] In the manufacturing method according to this embodiment, a polar monomer is used as a modifier for amorphous polypropylene. By grafting the polar monomer onto amorphous polypropylene, the polarity of the amorphous polypropylene is increased, which can improve its adhesion to other materials (for example, metal or inorganic materials, or plastic materials other than polypropylene).

[0031] Examples of polar monomers include methacrylic acid, acrylic acid, fumaric acid, maleic acid, crotonic acid, and maleic anhydride.

[0032] In conventional graft polymerization, maleic anhydride was commonly used as a modifying agent. This was because maleic anhydride contributes only to grafting and is less likely to produce side reactions. However, maleic anhydride has low reactivity, resulting in insufficient grafting efficiency. On the other hand, when methacrylic acid or acrylic acid is used as a modifying agent, although it is highly reactive, it also produces many side reactions that do not contribute to grafting (for example, the formation of polymers of the modifying agent that are not grafted), resulting in insufficient grafting efficiency. In contrast, the manufacturing method according to this embodiment can suppress the above-mentioned side reactions even when using highly reactive methacrylic acid or acrylic acid, thereby further improving graft efficiency. Therefore, although not particularly limited, the polar monomer is preferably methacrylic acid or acrylic acid, and more preferably methacrylic acid.

[0033] The amount of polar monomer used is preferably 0.5 to 50% by mass, more preferably 1.0 to 30% by mass, and even more preferably 2 to 10% by mass, based on the total mass of amorphous polypropylene and polar monomer. Using polar monomers at a concentration of 0.5% by mass or more tends to improve graft efficiency. By limiting the amount of polar monomers used to 50% by mass or less, it is possible to avoid the deterioration of the properties of amorphous polypropylene due to excessive grafting of polar monomers.

[0034] Polar monomers may be used individually or in combination of two or more. Polar monomers may be used in combination with ethylenically unsaturated monomers that do not contain polar groups (hereinafter also referred to as "non-polar monomers"). When polar monomers are used in combination with non-polar monomers, the amount of polar monomers is preferably 50% by mass or more, based on the total mass of the two monomers.

[0035] [Organic peroxide] In the manufacturing method according to this embodiment, an organic peroxide is used to generate radicals that initiate graft polymerization.

[0036] Organic peroxides are not particularly limited as long as they generate radicals, and known examples can be cited. Examples of organic peroxides include dialkyl peroxides, peroxyketals, peroxyesters, ketone peroxides, hydroperoxides, and diacyl peroxides. Examples of dialkylperoxides include di-t-butylperoxide, dicumylperoxide, α,α'-bis(t-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyn-3. Examples of peroxyketals include 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane and 2,2-bis(t-butylperoxy)butane. Examples of peroxyesters include t-butylperoxy-2-ethylhexyl monocarbonate, t-butylperoxybenzoate, t-butylperoxyisopropyl monocarbonate, and t-butylperoxymaleic acid. Examples of ketone peroxides include methyl ketone peroxide and cyclohexanone peroxide. Examples of hydroperoxides include cumene hydroperoxide, t-butyl hydroperoxide, and paramentane hydroperoxide. Examples of diacyl peroxides include benzoyl peroxide and lauroyl peroxide.

[0037] The amount of organic peroxide used is preferably 0.1 to 10% by mass, more preferably 0.2 to 6% by mass, and even more preferably 0.4 to 2% by mass, based on the total mass of amorphous polypropylene and polar monomer. Using organic peroxides at a concentration of 0.1% by mass or more tends to improve graft efficiency. By limiting the amount of organic peroxides used to 10% by mass or less, it tends to suppress β-cleavage of amorphous polypropylene or crosslinking between amorphous polypropylenes.

[0038] Organic peroxides may be used individually or in combination of two or more types.

[0039] [Electron-donating polyfunctional ethylenically unsaturated monomers (polyfunctional monomers)] In the manufacturing method according to this embodiment, polyfunctional monomers are used in combination with a chain transfer agent in order to improve graft efficiency and suppress changes in molecular weight.

[0040] In this specification, "polyfunctional" in polyfunctional monomer means that it contains two or more ethylenically unsaturated bonds. The number of ethylenically unsaturated bonds is preferably 2 to 4, and more preferably 2 or 3.

[0041] The polyfunctional monomer preferably contains vinyl groups and / or allyl groups. The total number of vinyl and allyl groups is preferably 2 or more, more preferably 2 to 4, and even more preferably 2 or 3. For example, the polyfunctional monomer preferably contains vinyl groups, and the number of vinyl groups is preferably 2 or more, more preferably 2 to 4, and even more preferably 2. For example, the polyfunctional monomer preferably contains allyl groups, and the number of allyl groups is preferably 2 or more, more preferably 2 to 4, and even more preferably 3.

[0042] In this specification, "electron-donating property" of a polyfunctional monomer means that it donates electrons to the ethylenically unsaturated bonds of the polyfunctional monomer. Such electron donation makes it easier for the ethylenically unsaturated bonds of the polyfunctional monomer to bond to electron-requiring polypropylene radicals before β-cleavage occurs.

[0043] In particular, the e-value proposed by Alfrey-Price is an indicator that represents the donation or withdrawal of electrons to the ethylenically unsaturated bonds of polyfunctional monomers. If this e-value is negative, it indicates that electrons have been donated to the ethylenically unsaturated bonds of the polyfunctional monomer. The e-value proposed by Alfrey-Price is described in the "Polymer Handbook 5th Edition (2009)" published by John Wiley and Sons Ltd.

[0044] The electron-donating group is preferably bonded directly to the vinyl group and / or allyl group, or via an ester bond.

[0045] Examples of electron-donating groups include aryl groups, heteroaryl groups, melamine groups, and isocyanuric groups. Examples of (hetero)aryl groups include 5-12 membered (hetero)aryl groups which may contain 1, 2, or 3 heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur; more specifically, 5 or 6 membered (hetero)aryl groups which may contain 1, 2, or 3 heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur; and more specifically, benzene rings.

[0046] The e-value of the polyfunctional monomer is preferably -2.5 to -0.05, more preferably -2 to -0.1, and even more preferably -1.5 to -0.2. Specific examples of polyfunctional monomers include divinylbenzene (e value: -0.8), triallyl isocyanurate (e value: -0.23), diallyl melamine (e value: -1.57), and diallyl phthalate (e value: -0.26). Among these, divinylbenzene (e value: -0.8) and triallyl isocyanurate (e value: -0.23) are more preferred.

[0047] The amount of polyfunctional monomer used is preferably 0.05 to 6% by mass, more preferably 0.1 to 3% by mass, and even more preferably 0.2 to 1% by mass, based on the total mass of amorphous polypropylene and polar monomer. By using a polyfunctional monomer of 0.05% by mass or more, graft efficiency tends to be further improved, and molecular weight reduction tends to be further suppressed. By limiting the amount of polyfunctional monomers used to 6% by mass or less, it is possible to avoid the deterioration of the properties of amorphous polypropylene due to excessive grafting of polar monomers.

[0048] Polyfunctional monomers may be used individually or in combination of two or more.

[0049] [Electron-donating chain transfer agent] In the manufacturing method according to this embodiment, a chain transfer agent is used in combination with a polyfunctional monomer to improve graft efficiency and suppress changes in molecular weight.

[0050] The chain transfer agent preferably has an ethylenically unsaturated bond. It is preferable that the chain transfer agent reacts with a polypropylene radical to graft substituents having an ethylenically unsaturated bond onto the polypropylene.

[0051] In this specification, "electron-donating" of a chain transfer agent means that it donates electrons to the portion of the chain transfer agent that reacts with polypropylene radicals. This electron donation makes it easier for the chain transfer agent to bond to polypropylene radicals before β-cleavage occurs. Specifically, the portion of the chain transfer agent that reacts with polypropylene radicals is an ethylenically unsaturated bond.

[0052] A benzene ring is effective as an electron-donating group, and it is preferable that the benzene ring is directly or via an ester group attached to the chain transfer agent portion that reacts with the polypropylene radical.

[0053] Specific examples of the chain transfer agent include, for example, the "α-methylstyrene structure" shown in formula (1) below, or the "naphthoquinone structure" shown in formula (2) below, and more preferably the "α-methylstyrene structure" shown in formula (1) below, which is a structure that causes addition-cleavage type chain transfer. [ka] [In the formula, R 1 R is an electron-donating group (e.g., a (hetero)aryl group, preferably a phenyl group), 2 is a (hetero)aryl group (preferably a phenyl group), a cyano group or an alkyl ester group (-COOR 4 Here, R 4 R represents an alkyl group having 1 to 4 carbon atoms. 3 This is hydrogen or an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group).

[0054] Examples of compounds represented by formula (1) include 2,4-diphenyl-1-pentene, α-methylstyrene dimer (2,4-diphenyl-4-methyl-1-pentene), 2-phenyl-4-cyano-1-pentene, 2-phenyl-4-cyano-4-methyl-1-pentene, α-(2-methyl-propanoate methyl)styrene, α-(2-methyl-propanoate ethyl)styrene, or α-(2-methyl-propanoate propyl)styrene. More preferably, among these, is α-methylstyrene dimer (2,4-diphenyl-4-methyl-1-pentene).

[0055] [ka] [In the formula, R 5 and R 6 Each of these is independently either a hydrogen atom or a hydroxyl group, or R 5 and R 6 These may form a benzene ring together with the carbon atoms to which they are bonded.

[0056] Examples of compounds represented by formula (2) include 1,4-naphthoquinone, lawsone, or 9,10-anthraquinone.

[0057] Details of electron-donating groups are as described in the section above [Electron-donating polyfunctional ethylenically unsaturated monomers (polyfunctional monomers)], and that information is quoted here.

[0058] The amount of chain transfer agent used is preferably 0.05 to 6% by mass, more preferably 0.1 to 5% by mass, and even more preferably 0.2 to 3% by mass, based on the total mass of amorphous polypropylene and polar monomer. By using a chain transfer agent of 0.05% by mass or more, graft efficiency tends to be further improved, and molecular weight reduction is more suppressed. By limiting the amount of chain transfer agent used to 6% by mass or less, it tends to be possible to avoid the deterioration of the properties of amorphous polypropylene due to excessive grafting of polar monomers.

[0059] The chain transfer agent may be used individually or in combination of two or more types.

[0060] [Melting and mixing] In the manufacturing method according to this embodiment, amorphous polypropylene, a polar monomer, an organic peroxide, a polyfunctional monomer, and a chain transfer agent are melt-kneaded at a temperature of 130 to 180°C to graft the polar monomer onto amorphous polypropylene and produce modified amorphous polypropylene.

[0061] In this embodiment, amorphous polypropylene with a low softening point is used, allowing for melt-mixing at a lower temperature. Specifically, the temperature is 130-180°C, preferably 140-180°C. Melt-mixing at such a temperature further improves graft efficiency and suppresses molecular weight changes. Since melt-mixing of crystalline polypropylene is usually carried out at 200°C or higher, such a low temperature is a condition unique to this embodiment.

[0062] The melt mixing temperature can be appropriately changed depending on the type of amorphous polypropylene and polar monomer used, and is preferably above the softening point of amorphous polypropylene - 10°C and below the boiling point of the polar monomer + 20°C. The reason the lower temperature limit is set to [the softening point of amorphous polypropylene - 10°C] is that in a melting and mixing machine, a high shear force is applied to amorphous polypropylene, causing it to soften at a temperature lower than its normal softening point. Furthermore, the reason for setting the upper temperature limit as [boiling point of polar monomer + 20°C] is that in a pressurized melting and mixing machine, polar monomers vaporize at a temperature higher than their normal boiling point.

[0063] The melting and kneading apparatus is not particularly limited as long as it is a known type, but examples include various extruders such as single-screw extruders and twin-screw extruders, and melting and kneading machines such as Banbury mixers, Brabenders, Plastographs, Hot Rolls, and Kneaders.

[0064] The time for melting and mixing is not particularly limited, but may be, for example, 1 to 30 minutes, or 2 to 20 minutes.

[0065] According to the manufacturing method of this embodiment, modified amorphous polypropylene can be produced with high graft efficiency. The graft efficiency (graft reaction rate) is preferably 45% or more, more preferably 50% or more, and even more preferably 60% or more. Since a higher graft efficiency is preferable, there is no particular upper limit, but realistic upper limits for graft efficiency can be given as, for example, 90%, 80%, or 70%. The graft reaction rate can be measured according to the method described in the examples.

[0066] According to the manufacturing method of this embodiment, modified amorphous polypropylene can be produced with suppressed molecular weight changes. The change in molecular weight can be expressed as a change in melt viscosity (melt viscosity ratio). The melt viscosity ratio is preferably 0.5 to 2.0, more preferably 0.8 to 1.5, even more preferably 0.9 to 1.1, and particularly preferably 1. The melt viscosity ratio can be measured according to the method described in the examples. [Examples]

[0067] The present invention will be described in more detail below using examples and comparative examples, but the technical scope of the present invention is not limited thereto. The various values ​​in the examples may be preferred lower or upper limits in the embodiments of the present invention. Alternatively, two similar values ​​in the examples may be combined as appropriate to form a preferred numerical range.

[0068] <Manufacturing of Modified Amorphous Polypropylene> [Raw materials] (Amorphous polypropylene) • RT2180 (REXtac polypropylene homopolymer, softening point: 157°C, melt viscosity at 190°C: 8.0 Pa·s) • RT2115 (REXtac polypropylene homopolymer, softening point: 155°C, melt viscosity at 190°C: 1.5 Pa·s)

[0069] (Polar monomers) • Methacrylic acid (MAA) (boiling point: 161℃) • Acrylic acid (AA) (boiling point: 141℃) • Maleic anhydride (MAN) (boiling point: 192°C) (Non-polar monomers) Methyl methacrylate (MMA) (boiling point: 101°C)

[0070] (Polyfunctional monomers) • Divinylbenzene (DVB) • Triallyl isocyanurate (TAIC)

[0071] (Electron-donating chain transfer agent) • α-methylstyrene dimer (αMSD) • 1,4-Naphthoquinone (1,4-NQ) (Non-electron-donating chain transfer agent) n-dodecyl mercaptan (NDM)

[0072] (organic peroxide) t-Butylperoxy-2-ethylhexyl monocarbonate (TBEC) 2,5-Dimethyl-2,5-bis(t-butylperoxy)hexane (DBPH) 2,5-Dimethyl-2,5-bis(t-butylperoxy)hexyn-3(DBPHY)

[0073] [Example 1] Using a kneader (MC15HT manufactured by Xplore), RT2180 (95 parts by mass), MAA (5 parts by mass), DVB (0.5 parts by mass), αMSD (0.5 parts by mass), and TBEC (1 part by mass) were melt-kneaded at 160°C, 70 rpm, and for 10 minutes to obtain modified amorphous polypropylene.

[0074] [Examples 2-13 and Comparative Examples 1-5] Modified amorphous polypropylene was obtained in the same manner as in Example 1, except that the type or amount of raw materials or the mixing conditions were changed as shown in Table 1.

[0075] <Measurement method> [Graft response rate] Modified amorphous polypropylene (1 g) obtained as the crude product in the examples and comparative examples was added to xylene (40 mL) and dissolved at 130°C. The resulting solution was added dropwise to methanol (400 mL) and precipitated. The precipitate was collected and vacuum-dried at 50°C for 1 hour to obtain purified modified amorphous polypropylene.

[0076] The obtained modified amorphous polypropylene (0.5g) was hot-pressed under three conditions: first (170°C, 0 MPa, 5 minutes), second (170°C, 1 MPa, 2 minutes), and then third (rapid cooling, 1 MPa, 2 minutes) to create a film, and its thickness was measured.

[0077] The obtained film was measured by transmission Fourier transform infrared spectroscopy (FR-IR) to obtain an infrared absorption spectrum, and a peak (1700 cm) attributable to MAA was identified. -1 ), peak caused by AA (1700cm) -1 ), or peaks caused by MAN (carboxylic acid anhydride: 1780 cm²) -1 Ring-opened carboxylic acid: 1780 cm -1 The area of ​​the peak was measured. Based on the peak area and the film thickness, the corrected peak area was calculated assuming a film thickness of 500 μm.

[0078] Based on the corrected peak area and a calibration curve using ethylene-methacrylic acid copolymer (EMAA) or maleic anhydride-modified polypropylene (MAN-PP) as standard samples, the amount (mass%) of polar monomer introduced into amorphous polypropylene was calculated. Next, the graft reaction rate was calculated using the following formula. The results are shown in Table 1.

[0079] Graft reaction rate (%) = {[Amount of polar monomer introduced into amorphous polypropylene (mass%)] / [Amount of polar monomer charged (mass%)]} × 100 (In the formula, "amount of polar monomer charged (mass%)" refers to the mass percentage of polar monomer, based on the total mass of amorphous polypropylene and polar monomer.)

[0080] [Melting viscosity and melting viscosity ratio] The melt viscosity of amorphous polypropylene as a raw material and the purified modified amorphous polypropylene was measured using a viscometer (MCR302e manufactured by Anton Paar) under the following conditions.

[0081] (Viscosity measurement conditions) Temperature: 180℃ Strain: 30% Frequency: 100 rad / s Plate: Cone-shaped plate (50mm diameter)

[0082] The ratio of the melt viscosity of modified amorphous polypropylene to the melt viscosity of amorphous polypropylene was calculated and defined as the melt viscosity ratio. The results are shown in Table 1. Since melt viscosity correlates with molecular weight, a melt viscosity ratio closer to 1 indicates that the change in molecular weight is suppressed.

[0083] [Table 1]

[0084] As shown in Table 1, in Examples 1 to 13, which used a combination of polyfunctional monomer and an electron-donating chain transfer agent and were melt-kneaded at low temperatures, both improved graft reaction rates and suppressed molecular weight changes were achieved. On the other hand, in Comparative Examples 1 and 2, which used only one of either a polyfunctional monomer or an electron-donating chain transfer agent, there were problems with both the graft reaction rate and the change in molecular weight. In Comparative Example 3, which used a non-electron-donating chain transfer agent, there were problems with the graft reaction rate. In Comparative Example 4, where melt-kneading was performed at high temperature, there were problems with both the graft reaction rate and the change in molecular weight. In Comparative Example 5, where a nonpolar monomer was used instead of a polar monomer, there were problems with the graft reaction rate.

Claims

1. Amorphous polypropylene and An ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group, Organic peroxides and, Electron-donating polyfunctional ethylenically unsaturated monomers, Electron-donating chain transfer agent, This includes melting and kneading at a temperature of 130 to 180°C. A method for producing modified amorphous polypropylene.

2. The manufacturing method according to claim 1, wherein the softening point of the amorphous polypropylene is 130 to 180°C.

3. The manufacturing method according to claim 1, wherein the weight-average molecular weight of the amorphous polypropylene is 5,000 to 500,000.

4. The manufacturing method according to claim 1, wherein the melt viscosity of the amorphous polypropylene at 190°C is 0.01 to 50 Pa·s.

5. The method for producing an ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group, wherein the monomer comprises at least one selected from the group consisting of methacrylic acid, acrylic acid, and maleic anhydride.

6. The method for producing the product according to claim 5, wherein the ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group includes methacrylic acid.

7. The method for producing the electron-donating polyfunctional ethylenically unsaturated monomer according to claim 1, wherein the electron-donating polyfunctional ethylenically unsaturated monomer has two or more vinyl groups or two or more allyl groups and has an aromatic ring or an isocyanuric ring.

8. The method for producing the product according to claim 7, wherein the electron-donating polyfunctional ethylenically unsaturated monomer comprises at least one selected from the group consisting of divinylbenzene and triallyl isocyanurate.

9. The electron-donating chain transfer agent is given by the following formula (1): 【Chemistry 1】 [In the formula, R １ is an aryl group or a heteroaryl group, R ２ is an aryl group, heteroaryl group, cyano group or alkyl ester group (-COOR ４ Here, R ４ ( is an alkyl group having 1 to 4 carbon atoms), R ３ [This is either a hydrogen or methyl group.] A method for producing a compound represented by any one of claims 1 to 8.

10. The manufacturing method according to claim 9, wherein the electron-donating chain transfer agent comprises an α-methylstyrene dimer.

11. The electron-donating chain transfer agent is given by the following formula (2): 【Chemistry 2】 [In the formula, R ５ and R ６ are each independently hydrogen or a hydroxyl group, or R ５ and R ６ may together with the carbon atom to which they are attached form a benzene ring] A method for producing a compound represented by any one of claims 1 to 8.

12. The manufacturing method according to any one of claims 1 to 8, wherein the melting and kneading temperature is at or above [the softening point of the amorphous polypropylene minus 10°C] and at or below [the boiling point of the ethylenically unsaturated monomer having a carboxyl group or an acid anhydride group plus 20°C].

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