Polymer composition, method for manufacturing polymer composition, method for manufacturing solution of crude polymer composition, and method for manufacturing crude polymer composition

Abstract

The purpose of the present invention is to provide: a polymer composition exhibiting little change in hue of a molded article and particularly having a low yellowness index (YI) value; a method for manufacturing a polymer composition exhibiting little change in hue of a molded article and particularly having a low yellowness index (YI) value; and a method for manufacturing a solution of a crude polymer composition and a method for manufacturing a crude polymer composition, each of which may be included as a stage in a method for manufacturing a polymer composition. The present invention relates to: a polymer composition comprising acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, wherein the total content of the dimethylfuran compounds is less than 15 mass ppm relative to the total mass of the polymer composition; and manufacturing methods for the polymer composition, a solution of a crude polymer composition, and a crude polymer composition, each of the methods comprising specific steps in a specific order.

Description

Polymer composition, method for producing polymer composition, method for producing solution of crude polymer composition, and method for producing crude polymer composition

[0001] The present invention relates to a polymer composition, a method for producing a polymer composition, a method for producing a solution of a crude polymer composition, and a method for producing a crude polymer composition.

[0002] Polypropylene (as used herein, the term "polypropylene" includes copolymers of propylene and other copolymerizable monomers, but does not include acid-modified polypropylene), a general-purpose polymer, is relatively inexpensive and has good moldability, heat resistance, solvent resistance, mechanical properties, appearance, and other properties, and is therefore processed into various molded products and used in a wide range of fields. However, polypropylene is basically composed of saturated hydrocarbons, and has poor chemical reactivity and low polarity, so there has been a demand for improvements in its adhesiveness, paintability, and printability.

[0003] One known method for improving these problems is to modify polypropylene by grafting an unsaturated carboxylic acid or its anhydride, such as maleic anhydride, onto the polypropylene. Such acid-modified polypropylene is produced by grafting an acid component using, as an initiator, an organic peroxide or a radical generated by thermal decomposition or the like (Patent Document 1).

[0004] The grafting reaction of polypropylene can be carried out in two ways: a solution modification method in which modification is carried out in an organic solvent, and a melt modification method in which modification is carried out while melting by heating. The solution modification method has the advantages of being able to proceed at a relatively low temperature, making it easy to carry out the grafting reaction uniformly, and also making it easy to obtain acid-modified polypropylene with a high grafting amount.

[0005] Japanese Patent Application Publication No. 2006-328388

[0006] However, polymer compositions containing acid-modified polypropylene produced by a solution modification method have a problem in that sheets produced by hot pressing the compositions have variations in yellowness index (hereinafter also referred to as "YI") depending on the production history. When such polymer compositions are used to mold films, sheets, bottles, etc., the color of the molded products is problematic.

[0007] Therefore, an object of the present invention is to provide a polymer composition that causes little change in hue of a molded product, and in particular, causes a small yellowness index (YI) value. Another object of the present invention is to provide a method for producing a polymer composition that causes little change in hue of a molded product, and in particular, causes a small yellowness index (YI) value. Another object of the present invention is to provide a method for producing a solution of a crude polymer composition, which can be included as a step in the method for producing the polymer composition, and a method for producing a crude polymer composition.

[0008] In view of the above circumstances, the present inventors have conducted extensive research and have surprisingly found that, in a polymer composition containing acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, by adjusting the total content of the dimethylfuran compounds relative to the total mass of the polymer composition to less than a specific numerical value, a polymer composition can be obtained in which the hue of a molded product changes little, and in particular the yellowness index (YI) value is small, thereby completing the present invention. Furthermore, the present inventors have found that a production method including specific steps in a specific order enables the production of a polymer composition in which the hue of a molded product changes little, and in particular the yellowness index (YI) value is small, thereby completing the present invention.

[0009] That is, the present invention provides the following.

[0010] A first aspect of the present invention relates to a polymer composition containing an acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, wherein the total content of the dimethylfuran compounds relative to the total mass of the polymer composition is less than 15 ppm by mass.

[0011] A second aspect of the present invention relates to the polymer composition according to the first aspect, wherein the total content of the dimethylfuran compounds relative to the total mass of the polymer composition is 0.5 ppm by mass or more.

[0012] A third aspect of the present invention relates to the polymer composition according to the first or second aspect, wherein the total content of the dimethylfuran compounds relative to the total mass of the polymer composition is 1 ppm by mass or more.

[0013] A fourth aspect of the present invention relates to the polymer composition according to any one of the first to third aspects, wherein the total content of the dimethylfuran compounds relative to the total mass of the polymer composition is 12 ppm by mass or less.

[0014] A fifth aspect of the present invention relates to the polymer composition of any one of the first to fourth aspects, wherein the polymer composition has a melt flow rate of 150 to 2000 g / 10 min as measured in accordance with JIS K 7210:2014 under conditions of 180°C and a load of 21.2 N.

[0015] A sixth aspect of the present invention relates to the polymer composition according to any one of the first to fifth aspects, wherein the graft ratio of the acid-modified polypropylene is 1.0 to 20% by mass.

[0016] A seventh aspect of the present invention relates to a food packaging material comprising the polymer composition of any one of the first to sixth aspects.

[0017] Aspect 8 of the present invention relates to a medical product comprising the polymer composition of any one of aspects 1-6.

[0018] A ninth aspect of the present invention relates to an automotive part comprising the polymer composition of any one of the first to sixth aspects.

[0019] A tenth aspect of the present invention relates to a battery component comprising the polymer composition of any one of the first to sixth aspects.

[0020] An eleventh aspect of the present invention relates to the use of the polymer composition according to any one of the first to sixth aspects as a food packaging material.

[0021] A twelfth aspect of the present invention relates to the use of the polymer composition according to any one of the first to sixth aspects in a medical product.

[0022] A thirteenth aspect of the present invention relates to the use of the polymer composition according to any one of the first to sixth aspects in an automobile part.

[0023] A fourteenth aspect of the present invention relates to the use of the polymer composition according to any one of the first to sixth aspects in a battery component.

[0024] Aspect 15 of the present invention relates to a method for producing a polymer composition according to any one of Aspects 1 to 6, the method comprising the following steps 1A to 5A in this order: (Step 1A) A step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives, to obtain a solution 1A containing the polypropylene and the acid component; (Step 2A) A step of adding an organic peroxide to the solution 1A, to obtain a solution 2A containing an acid-modified polypropylene; (Step 3A) A step of separating the solution 2A into a polymer composition and a filtrate, to obtain the polymer composition; (Step 4A) A step of purifying the filtrate, to obtain a treatment solvent; and (Step 5A) A step of reusing the treatment solvent as part or all of the reaction solvent in Step 1A.

[0025] A sixteenth aspect of the present invention relates to the production method of Aspect 15, wherein the step 3A comprises a step of separating the solution 2A into the polymer composition and the filtrate by crystallization purification.

[0026] A seventeenth aspect of the present invention relates to the production method of the fifteenth or sixteenth aspect, wherein the purification treatment in the step 4A includes distillation purification.

[0027] Aspect 18 of the present invention relates to the production method according to any one of Aspects 15 to 17, wherein the total content of at least one selected from the group consisting of acetone and its derivatives is 0.2 mass % or less relative to the total mass of the treatment solvent.

[0028] Aspect 19 of the present invention relates to a method for producing a polymer composition according to any one of Aspects 1 to 6, comprising the following steps 1B to 4B in this order: (Step 1B) heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives to obtain a solution 1B containing the polypropylene and the acid component; (Step 2B) adding an organic peroxide to the solution 1B to obtain a solution 2B containing an acid-modified polypropylene; (Step 3B) separating the solution 2B into a polymer composition and a filtrate by crystallization purification to obtain the polymer composition; and (Step 4B) purifying the filtrate by distillation.

[0029] Aspect 20 of the present invention relates to a method for producing a solution of a crude polymer composition containing acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, the method comprising the following Steps 1C to 2C in this order: (Step 1C) A step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one compound selected from the group consisting of acetone and its derivatives to obtain Solution 1C containing the polypropylene and the acid component; and (Step 2C) A step of adding an organic peroxide to Solution 1C to obtain Solution 2C of a crude polymer composition containing acid-modified polypropylene.

[0030] Aspect 21 of the present invention relates to a method for producing a crude polymer composition containing acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, the method comprising the following Steps 1D to 3D in this order: (Step 1D) A step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives to obtain a solution 1D containing the polypropylene and the acid component; (Step 2D) A step of adding an organic peroxide to the solution 1D to obtain a solution 2D containing the acid-modified polypropylene; and (Step 3D) A step of separating the solution 2D into a crude polymer composition and a filtrate to obtain the crude polymer composition.

[0031] Aspect 22 of the present invention relates to the production method of Aspect 21, further comprising, after Step 3D, Steps 4D to 5D in this order: (Step 4D) a step of purifying the filtrate to obtain a treatment solvent; and (Step 5D) a step of reusing the treatment solvent as part or all of the reaction solvent in Step 1D.

[0032] A twenty-third aspect of the present invention relates to the production method of the twenty-first or twenty-second aspect, wherein the step 3D comprises separating the solution 2D into the crude polymer composition and the filtrate by crystallization purification.

[0033] A twenty-fourth aspect of the present invention relates to the production method of the twenty-second aspect, wherein the purification treatment in the step 4D includes distillation purification.

[0034] A twenty-fifth aspect of the present invention relates to the production method of the twenty-second or twenty-fourth aspect, wherein the total content of at least one selected from the group consisting of acetone and its derivatives is 0.2 mass % or less relative to the total mass of the treatment solvent.

[0035] A twenty-sixth aspect of the present invention relates to the production method according to any one of the twenty-first to twenty-five aspects, wherein the total content of the dimethylfuran compounds relative to the total mass of the crude polymer composition is less than 15 ppm by mass.

[0036] According to the present invention, it is possible to provide a polymer composition which produces a molded product with little change in hue, particularly a small yellowness index (YI) value. Furthermore, according to the present invention, it is possible to provide a method for producing a polymer composition which produces a molded product with little change in hue, particularly a small yellowness index (YI) value. Furthermore, according to the present invention, it is possible to provide a method for producing a solution of a crude polymer composition, which can be included as a step in the method for producing the polymer composition, and a method for producing a crude polymer composition.

[0037] Embodiments of the present invention will be described in detail below, but the following embodiments are merely examples of embodiments of the present invention and the present invention is not limited thereto. The present invention can be implemented with any modifications within the scope of the gist of the present invention. In this specification, when a numerical value or physical property value is enclosed before and after the prefix "~", the values ​​before and after the prefix are included. Furthermore, in this specification, with respect to numerical ranges described in stages, the upper or lower limit of a numerical range in one stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the examples.

[0038] <Polymer Composition> A polymer composition according to an embodiment of the present invention is a polymer composition containing an acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, wherein the total content of the dimethylfuran compounds relative to the total mass of the polymer composition is less than 15 ppm by mass. In this specification, the total content of dimethylfuran compounds refers to the content of only one type of dimethylfuran compound. In addition, in cases where the dimethylfuran compound consists of two or more types of dimethylfuran compounds, it refers to the sum of the contents of the respective compounds. Components that may be contained in the polymer composition will be described in detail below.

[0039] [Acid-modified polypropylene] The polymer composition according to the embodiment of the present invention contains an acid-modified polypropylene. The acid-modified polypropylene is obtained by grafting an acid component onto polypropylene. In the polymer composition according to the embodiment of the present invention, the polymer component is preferably an acid-modified polypropylene. In one embodiment, the acid-modified polypropylene can be obtained in a form contained in the polymer composition by the method for producing a polymer composition described below.

[0040] (Grafting rate) The grafting rate means the content of unsaturated carboxylic acid and / or derivative components thereof in an acid-modified polypropylene as a standard sample, which is previously quantified by nuclear magnetic resonance measurement, and measured with an infrared spectrometer using a calibration curve created from the quantitative values. For example, the grafting rate is the absorption specific to carboxylic acid and / or derivatives thereof in a sample press-molded into a sheet having a thickness of about 100 μm, specifically, 1900 to 1600 cm －１ It can be determined by measuring the carbonyl characteristic absorption (C=O stretching vibration band).

[0041] In addition, unsaturated carboxylic acids and / or derivatives thereof that have not been subjected to the reaction and have not reacted with the raw polypropylene may remain in the acid-modified polypropylene. As a pretreatment for such residues, a press-molded sample is placed in a Soxhlet extractor, refluxed with acetone at 80°C for 1 hour, and then dried at 80°C for 2 hours. The resulting sheet is then measured as a sample, and the amount of unsaturated carboxylic acids and / or derivatives thereof graft-polymerized onto the polypropylene in the measurement sample can be determined. In the examples described below, the amount of unsaturated carboxylic acids and / or derivatives thereof remaining in the acid-modified polypropylene was negligible, at 0.01% by mass or less, so the above-mentioned pretreatment was not performed.

[0042] A graft ratio of 1.0% by mass or more is preferred because a large amount of polar groups, such as carboxylic acid groups, contained in the acid component can be introduced into the polymer, thereby enhancing adhesion to polar polymers. A graft ratio of 20% by mass or less is preferred because a decrease in molecular weight during acid modification can be suppressed, thereby ensuring physical properties such as adhesive strength and impact resistance.

[0043] In the polymer composition according to the embodiment of the present invention, for example, the graft ratio of the acid-modified polypropylene may be 1.0 to 20% by mass.

[0044] (Melting point) There is no particular limitation on the melting point of the acid-modified polypropylene, but it is preferably 90°C or higher, more preferably 120°C or higher. A melting point of 90°C or higher allows for heat sterilization by boiling, while a melting point of 120°C or higher allows for use in retort packs. The melting point can be measured using a differential scanning calorimeter (DSC), usually at a temperature increase and decrease rate of 10°C / min. However, the melting point is usually 200°C or lower.

[0045] Although there is no particular limitation on the amount of elution of the acid-modified polypropylene in n-heptane (25°C, 60 minutes) measured in accordance with the elution test prescribed in the Food Sanitation Act, it is preferably 150 mass ppm or less, and more preferably 30 mass ppm or less. High oil resistance is preferable because it can be used as a packaging material for highly oily substances such as oily foods.

[0046] [Dimethylfuran Compound] The dimethylfuran compound is a compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran. The polymer composition according to an embodiment of the present invention contains a dimethylfuran compound. The dimethylfuran compound is derived from at least one selected from the group consisting of acetone and derivatives thereof contained in the reaction solvent used in the production method described below. The dimethylfuran compound is thought to be produced via some kind of reaction using at least one selected from the group consisting of acetone and derivatives thereof contained in the reaction solvent as a starting material.

[0047] The total content of dimethylfuran compounds relative to the total mass of the polymer composition is less than 15 ppm by mass, preferably 12 ppm by mass or less, and more preferably 11 ppm by mass or less. If the total content of dimethylfuran compounds relative to the total mass of the polymer composition is 15 ppm by mass or more, the change in hue of a molded product of the polymer composition, particularly the yellowness index (YI) value, will be large. On the other hand, there is no particular restriction on the lower limit of the total content of dimethylfuran compounds relative to the total mass of the polymer composition, but it can be, for example, 0.5 ppm by mass or more, 0.7 ppm by mass or more, or 1 ppm by mass or more.

[0048] Examples of a method for reducing the total content of dimethylfuran compounds to less than 15 ppm by mass relative to the total mass of the polymer composition include purifying the reaction solvent used in producing the acid-modified polypropylene by distillation to remove acetone and its derivatives, and repeatedly performing the crystallization purification described below.

[0049] [Other Components] (Additives) The polymer composition according to the embodiment of the present invention may contain various additives as other components. Examples of such additives include antioxidants and polymer stabilizers such as metal soaps and hydrotalcite. When additives are contained, the content is preferably 1% by mass or less, more preferably 0.7% by mass or less, and even more preferably 0.5% by mass or less, relative to the total mass of the polymer composition.

[0050] [Properties of Polymer Composition] (YI) The lower the YI of the polymer composition according to the embodiment of the present invention, the better. For example, it is preferably 40 or less, more preferably 35 or less, and even more preferably 30 or less. When the YI of the polymer composition is in the above range, problems with the hue of the molded product are unlikely to occur, even when the polymer composition is used to mold, for example, a film, a sheet, or a bottle. On the other hand, there is no particular restriction on the lower limit of the YI of the polymer composition, but it can be, for example, 1 or more, 2 or more, or 3 or more.

[0051] For example, the obtained polymer composition is processed into a sheet, and the YI can be measured for the obtained sheet sample using a color difference meter.

[0052] (Melt Flow Rate) In the polymer composition according to the embodiment of the present invention, the melt flow rate (hereinafter also referred to as "MFR") measured in accordance with JIS K 7210:2014 under conditions of 180°C and a load of 21.2 N is not particularly limited, but is preferably 150 g / 10 min or more, more preferably 170 g / 10 min or more, and even more preferably 200 g / 10 min or more. Also, it is preferably 2000 g / 10 min or less, more preferably 1800 g / 10 min or less, and even more preferably 1500 g / 10 min or less. A melt flow rate of 150 g / 10 min or more is preferable because it improves the dispersibility of the polymer composition containing the acid-modified polypropylene in other polymers such as polypropylene. Furthermore, a melt flow rate of 2000 g / 10 min or less is preferable because it can suppress a decrease in the mechanical strength of the acid-modified polypropylene.

[0053] The polymer composition according to an embodiment of the present invention may have a melt flow rate of 150 to 2000 g / 10 min, measured at 180° C. and a load of 21.2 N in accordance with JIS K 7210:2014.

[0054] [Uses of Polymer Composition] The polymer composition according to an embodiment of the present invention exhibits little change in the hue of molded products, particularly a small yellowness index (YI) value, and therefore can be suitably used for, for example, food packaging materials such as food packaging films and trays; medical packaging materials such as infusion bags, nutritional food / liquid food bags, and ostomy bags; medical device parts for joining injection-molded parts such as drip tubes and syringes with metal needles; medical products such as fluid transport devices such as bottles and tubes for medical use, and pharmaceutical containers such as pharmaceutical tubes and pharmaceutical bottles; automotive parts such as fuel tanks and fuel tubes, automotive coolant tubes, especially electric vehicle coolant tubes; and battery parts such as exterior films and tab lead films for secondary batteries in the fields of electronics, automobiles, and robotics. The polymer composition according to an embodiment of the present invention can be suitably used for automotive parts, particularly for applications requiring high cooling efficiency in a limited space, such as coolant tubes for electric vehicles. In electric vehicles, batteries tend to become larger in order to achieve higher power output and longer driving range, but in order to maintain the interior volume (interior space) of the vehicle, a cooling system in which coolant tubes are efficiently arranged in a more limited space is required. The polymer composition according to the embodiment of the present invention has excellent adhesive properties and can therefore be suitably used in applications such as electric vehicle coolant tubes.

[0055] That is, preferred examples of embodiments of the present invention include food packaging materials, medical products, automobile parts, and battery parts containing the above-mentioned polymer composition. Also, preferred examples of embodiments of the present invention include use of the above-mentioned polymer composition in food packaging materials, medical products, automobile parts, and battery parts.

[0056] <Method for Producing Polymer Composition> A method for producing a polymer composition according to an embodiment of the present invention comprises the following steps 1A to 5A in this order (hereinafter also referred to as "production method A"). (Step 1A) A step of dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof under heating in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives, to obtain a solution 1A containing the polypropylene and the acid component. (Step 2A) A step of adding an organic peroxide to the solution 1A, to obtain a solution 2A containing an acid-modified polypropylene. (Step 3A) A step of separating the solution 2A into a polymer composition and a filtrate, to obtain the polymer composition. (Step 4A) A step of purifying the filtrate to obtain a treatment solvent. (Step 5A) A step of reusing the treatment solvent as part or all of the reaction solvent in step 1A.

[0057] A method for producing a polymer composition according to another embodiment of the present invention comprises the following steps 1B to 4B in this order (hereinafter also referred to as "production method B"). (Step 1B) A step of dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof under heating in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives, to obtain solution 1B containing polypropylene and the acid component. (Step 2B) A step of adding an organic peroxide to solution 1B, to obtain solution 2B containing acid-modified polypropylene. (Step 3B) A step of separating solution 2B into a polymer composition and a filtrate by crystallization purification, to obtain the polymer composition. (Step 4B) A step of purifying the filtrate by distillation.

[0058] The preferred range of the polymer composition in the method for producing a polymer composition according to an embodiment of the present invention and the method for producing a polymer composition according to another embodiment of the present invention is the same as the range described above in <Polymer composition>.

[0059] [Production Method A: Step 1A] Step 1A in Production Method A is a step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and derivatives thereof, to obtain a solution 1A containing the polypropylene and the acid component.

[0060] (Components in Step 1A) The components in Step 1A of Production Method A, namely, polypropylene, acid component, aromatic hydrocarbon solvent, and reaction solvent, will be described in detail below.

[0061] Polypropylene In one embodiment, various known propylene-based polymers can be used as the polypropylene, and are not particularly limited. Examples of such polypropylene include propylene homopolymers, copolymers of ethylene and propylene, copolymers of propylene with other comonomers, such as butene-1, pentene-1, hexene-1, heptene-1, octene-1, cyclopentene, cyclohexene, and norbornene, and copolymers of two or more of these comonomers. The α-olefin comonomer is preferably an α-olefin comonomer having 2 to 6 carbon atoms. The polypropylene may be a random copolymer or a block copolymer. Furthermore, the polypropylene may be a mixture thereof.

[0062] When the polypropylene is a copolymer or a mixture, it preferably contains at least 30% by mass of a polypropylene component, more preferably 50% by mass or more, and even more preferably 70% by mass or more. However, a propylene homopolymer is most preferred. The higher the propylene content in the monomers constituting the polypropylene, the higher the heat resistance and the tendency for improved adhesion to polypropylene. Furthermore, it is less likely to gel, and the occurrence of defects such as fisheyes is suppressed.

[0063] As the polypropylene, isotactic polypropylene is preferred. Isotactic polypropylene is preferred because it has higher crystallinity and excellent rigidity, heat resistance, and oil resistance compared to polypropylenes with other stereoregularities such as atactic and syndiotactic. Because of its excellent rigidity, it can maintain strength even in relatively thin laminates, making it suitable for use as containers molded from laminate sheets, etc. Furthermore, its excellent heat resistance allows for high-temperature molding, and when used for food or medical purposes, it is advantageous from a hygienic perspective, as it can be heat sterilized. Furthermore, higher heat resistance is required when used as a retort pack. Isotactic polypropylene is also preferred because it is a general-purpose product and is therefore inexpensive, allowing for the supply of inexpensive products.

[0064] The molecular weight of the polypropylene is not particularly limited as long as it does not significantly deviate from the object of the present invention, but since the molecular weight tends to decrease due to β-cleavage reaction during the graft reaction, a higher molecular weight is preferable, and the MFR measured at 230°C and 21.2 N in accordance with JIS K 7210:2014 is preferably 0.01 g / 10 min or more, and more preferably 0.1 g / 10 min or more.

[0065] The MFR is preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less. One type of polypropylene may be used alone, or two or more types may be used in combination.

[0066] Acid Component In one embodiment, the acid component is at least one selected from the group consisting of unsaturated carboxylic acids and derivatives thereof. The acid component is not particularly limited as long as it does not significantly deviate from the objectives of the present invention, but is preferably an unsaturated carboxylic acid having two or more carboxyl groups and a derivative thereof. Specific examples of the acid component include unsaturated carboxylic acids such as maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, aconitic acid, and crotonic acid; and carboxylic anhydrides such as maleic anhydride, itaconic anhydride, and citraconic anhydride. Maleic acid and maleic anhydride are preferred, and maleic anhydride is particularly preferred. The acid component may be used alone or in combination of two or more.

[0067] The amount of the acid component used is not particularly limited, but is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of polypropylene, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less.

[0068] Aromatic Hydrocarbon Solvents The aromatic hydrocarbon solvent is not particularly limited, but examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene, and tert-butylbenzene; and halogenated aromatic hydrocarbons such as monochlorobenzene and o-dichlorobenzene. Among these, toluene, xylene, tert-butylbenzene, and monochlorobenzene are preferred. The aromatic hydrocarbon solvents may be used alone or in combination of two or more.

[0069] The amount of the aromatic hydrocarbon solvent used is not particularly limited, but is preferably 300 parts by mass or more, more preferably 350 parts by mass or more, and even more preferably 400 parts by mass or more, relative to 100 parts by mass of polypropylene, and is preferably 1500 parts by mass or less, more preferably 1200 parts by mass or less, and even more preferably 1000 parts by mass or less.

[0070] Reaction Solvent The reaction solvent comprises an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives. The at least one selected from the group consisting of acetone and its derivatives contained in the reaction solvent can be mixed in, for example, the step of separating solution 2A into a polymer composition and a filtrate to obtain a polymer composition (step 3A), the step of reusing the treatment solvent as part or all of the reaction solvent in step 1A (step 5A), or the step of separating solution 2B into a polymer composition and a filtrate by crystallization purification to obtain a polymer composition (step 3B).

[0071] The total content of at least one selected from the group consisting of acetone and its derivatives in the reaction solvent is not particularly limited, but is preferably 1500 ppm by mass or less, more preferably 1300 ppm by mass or less, and even more preferably 1000 ppm by mass or less. On the other hand, the lower limit of the total content of at least one selected from the group consisting of acetone and its derivatives in the reaction solvent is not particularly limited, but can be, for example, 30 ppm by mass or more, 40 ppm by mass or more, or 50 ppm by mass or more.

[0072] Here, the acetone derivatives generally refer to compounds that are produced using acetone as a starting material, and examples of such compounds include mesityl oxide and 2,5-hexanedione.

[0073] (Heat dissolution) Heat dissolution is a step of dissolving polypropylene and an acid component in a heated reaction solvent. When carrying out step 2A, the heat dissolution is preferably carried out under an inert gas atmosphere such as nitrogen gas. When carrying out step 2A, the heating temperature is preferably in the range of the boiling point of the reaction solvent, specifically 80°C to 180°C. There are no particular restrictions on the order in which the polypropylene, acid component, and reaction solvent are charged, but from a manufacturing perspective, it is preferable to charge the reaction solvent first, followed by the polypropylene and acid component.

[0074] [Production Method A: Step 2A] Step 2A in Production Method A is a step of adding an organic peroxide to Solution 1A to obtain Solution 2A containing acid-modified polypropylene.

[0075] (Components in Step 2A) The organic peroxide, which is a component in Step 2A of Production Method A, will be described in detail below.

[0076] Organic Peroxides The organic peroxide is not particularly limited, but examples thereof include dialkyl peroxides such as dicumyl peroxide and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; peroxyketals such as 1,1-di(tert-butylperoxy)cyclohexane and 1,1-di(tert-hexylperoxy)cyclohexane; and peroxyesters such as tert-butylperoxyisopropyl monocarbonate, tert-hexylperoxyisopropyl monocarbonate, and tert-hexylperoxy 2-ethylhexyl monocarbonate. Of these, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-di(tert-butylperoxy)cyclohexane, and tert-butylperoxyisopropyl monocarbonate are preferred, and dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and tert-butylperoxyisopropyl monocarbonate are more preferred, since the grafting reaction rate is higher than the β-cleavage rate.

[0077] (Reaction Conditions) There are no particular limitations on the reaction conditions after adding the organic peroxide. In one embodiment, the reaction temperature can be in the range of 20°C to 160°C. The reaction time can be in the range of 1 hour to 15 hours. This allows for the production of Solution 2A.

[0078] [Production Method A: Step 3A] Step 3A in Production Method A is a step of separating the solution 2A into a polymer composition and a filtrate to obtain a polymer composition.

[0079] (Components in Step 3A) The filtrate, which is a component in Step 3A of Production Method A, will be described in detail below.

[0080] Filtrate The filtrate is the liquid remaining after the polymer composition has been separated from the solution 2A. The filtrate contains an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives. The total content of the at least one selected from the group consisting of acetone and its derivatives relative to the total mass of the filtrate is preferably 10 to 85% by mass, more preferably 15 to 75% by mass, and even more preferably 20 to 65% by mass. A content of 10% by mass or more is preferred because it increases the amount of precipitation of acid-modified polypropylene. A content of 85% by mass or less is preferred because it increases the efficiency of removing components containing at least one selected from the group consisting of acetone and its derivatives from the filtrate and / or purifying it to obtain a treatment solvent.

[0081] (Method for Separating Polymer Composition from Solution 2A) The method for separating the polymer composition from Solution 2A is not particularly limited, and examples thereof include a method including crystallization purification. That is, Step 3A can include a step of separating Solution 2A into the polymer composition and a filtrate by crystallization purification.

[0082] In crystallization purification, examples of the solvent added to precipitate the acid-modified polypropylene include ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; and alcohols such as methanol and ethanol. Among these, acetone and methyl ethyl ketone are preferred, with acetone being more preferred, from the viewpoints of ease of separation from the aromatic hydrocarbon solvent and suppression of side reactions.

[0083] For the purpose of removing the remaining aromatic hydrocarbon solvent, the acid-modified polypropylene precipitated by the crystallization purification may be further washed with the same solvent as that added in the purification.

[0084] [Production Method A: Step 4A] Step 4A in Production Method A is a step of purifying the filtrate to obtain a treated solvent.

[0085] (Components in Step 4A) The treatment solvent, which is a component in Step 4A of Production Method A, will be described in detail below.

[0086] Treatment Solvent The treatment solvent is obtained by purifying the filtrate and contains an aromatic hydrocarbon solvent and at least one solvent selected from the group consisting of acetone and its derivatives.

[0087] The total content of at least one selected from the group consisting of acetone and its derivatives relative to the total mass of the treatment solvent is lower than the content in the filtrate. The total content of at least one selected from the group consisting of acetone and its derivatives relative to the total mass of the treatment solvent is preferably 0.2 mass% or less, more preferably 0.15 mass% or less, and even more preferably 0.1 mass% or less. The lower the content, the better, and there is no particular lower limit, but it can be, for example, 0.001 mass% or more, 0.005 mass% or more, or 0.01 mass% or more.

[0088] (Method for Obtaining Treated Solvent) The treated solvent is obtained by purifying the filtrate. There are no particular limitations on the method of treatment and purification, but it is preferable that it includes distillation purification and purification in which water-soluble components are removed by water extraction. From the viewpoint of reducing the total content of at least one selected from the group consisting of acetone and its derivatives relative to the total mass of the treated solvent, it is preferable that the purification treatment in Step 4A includes distillation purification.

[0089] Examples of distillation purification include simple distillation, which utilizes the difference in boiling points of components contained in the filtrate, and precision distillation, which improves separation efficiency by filling a distillation column with a packing material.From the viewpoint of separating at least one member selected from the group consisting of acetone and its derivatives, precision distillation is preferred.

[0090] [Production Method A: Step 5A] Step 5A in Production Method A is a step of reusing the treatment solvent obtained in Step 4A as a part or all of the reaction solvent in Step 1A.

[0091] There are no particular limitations on the method for reusing the treatment solvent obtained in step 4A as the reaction solvent in step 1A. For example, the treatment solvent alone can be used as the reaction solvent, or the treatment solvent can be blended with an aromatic hydrocarbon-based solvent (a new, not recycled product) and used.

[0092] [Production Method B: Step 1B] Step 1B in Production Method B is a step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and derivatives thereof, to obtain a solution 1B containing polypropylene and the acid component.

[0093] (Components in Step 1B) The components in Step 1B of Production Method B, that is, the aromatic hydrocarbon solvent, polypropylene, and acid component, are the same as those described for Step 1A of Production Method A.

[0094] (Heat Dissolution) The heat dissolution conditions may be the same as those described for step 1A of production method A.

[0095] [Production Method B: Step 2B] Step 2B in Production Method B is a step of adding an organic peroxide to Solution 1B to obtain Solution 2B containing acid-modified polypropylene.

[0096] (Components in Step 2B) The organic peroxide, which is a component in Step 2B of Production Method B, is the same as that described in Step 2A of Production Method A.

[0097] (Reaction Conditions) The reaction conditions after adding the organic peroxide can be the same as those described for step 2A of production method A. This makes it possible to obtain solution 2B.

[0098] [Production Method B: Step 3B] Step 3B in Production Method B is a step of separating Solution 2B into a polymer composition and a filtrate by crystallization purification to obtain a polymer composition.

[0099] The crystallization purification can be the same as that described in step 3A of production method A. In this way, a polymer composition can be obtained.

[0100] [Production Method B: Step 4B] Step 4B in Production Method B is a step of purifying the filtrate by distillation.

[0101] The distillation purification can be the same as that described in step 4A of production method A.

[0102] [Other Steps] Production method A and production method B may include any steps in addition to the steps described above. Examples of such steps include nitrogen bubbling of the reaction solution before adding the organic peroxide, a step of extracting the reaction solution with water, a step of decolorizing the reaction solution, a step of drying the acid-modified polypropylene, a step of pulverizing the acid-modified polypropylene, etc.

[0103] <Method for Producing a Solution of Crude Polymer Composition> A method for producing a solution of a crude polymer composition according to an embodiment of the present invention is a method for producing a solution of a crude polymer composition containing an acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, and includes the following steps 1C to 2C in this order (hereinafter also referred to as "Production Method C"). (Step 1C) A step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one compound selected from the group consisting of acetone and its derivatives, to obtain a solution 1C containing the polypropylene and the acid component. (Step 2C) A step of adding an organic peroxide to the solution 1C to obtain a solution 2C of a crude polymer composition containing an acid-modified polypropylene.

[0104] The method for producing a solution of a crude polymer composition according to an embodiment of the present invention may be included as a step in the method for producing the polymer composition.

[0105] [Production Method C: Step 1C] Step 1C in Production Method C is a step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and derivatives thereof, to obtain a solution 1C containing the polypropylene and the acid component.

[0106] (Components in Step 1C) The components in Step 1C of Production Method C, namely, polypropylene, acid component, aromatic hydrocarbon solvent, and reaction solvent, are the same as those described in Step 1A of Production Method A.

[0107] (Heat Dissolution) The heat dissolution conditions may be the same as those described for step 1A of production method A.

[0108] [Production Method C: Step 2C] Step 2C in Production Method C is a step of adding an organic peroxide to Solution 1C to obtain Solution 2C of a crude polymer composition containing acid-modified polypropylene.

[0109] (Components in Step 2C) The organic peroxide, which is a component in Step 2C of Production Method C, is the same as that described for Step 2A of Production Method A. The crude polymer composition, which is a component in Step 2C of Production Method C, will be described in detail below.

[0110] Crude Polymer Composition The crude polymer composition is similar to that described in the above <Polymer Composition>, except that the total content of dimethylfuran compounds relative to the total mass is not limited to less than 15 ppm by mass, and the preferred range is also similar. That is, the total content of dimethylfuran compounds relative to the total mass of the crude polymer composition may be 15 ppm by mass or more, or may be less than 15 ppm by mass. When an extremely low value is required for the total content of dimethylfuran compounds relative to the total mass of the polymer composition, further purification of the polymer composition may be required even if the content is less than 15 ppm by mass. In such cases, a crude polymer composition can be obtained even if the total content of dimethylfuran compounds relative to the total mass of the polymer composition is less than 15 ppm by mass. When the total content of dimethylfuran compounds relative to the total mass of the crude polymer composition is less than 15 ppm by mass, preferred embodiments of the crude polymer composition are similar to those described in the above <Polymer Composition>.

[0111] (Reaction Conditions) The reaction conditions after adding the organic peroxide may be the same as those described in step 2A of production method A.

[0112] [Other Steps] Production method C may include any steps other than those described above, such as bubbling nitrogen through the reaction solution before adding the organic peroxide, extracting the reaction solution with water, decolorizing the reaction solution, drying the acid-modified polypropylene, and pulverizing the acid-modified polypropylene.

[0113] <Method for Producing Crude Polymer Composition> A method for producing a crude polymer composition according to an embodiment of the present invention is a method for producing a crude polymer composition containing an acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, and includes the following steps 1D to 3D in this order (hereinafter also referred to as "Production Method D"). (Step 1D) A step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives to obtain a solution 1D containing the polypropylene and the acid component. (Step 2D) A step of adding an organic peroxide to the solution 1D to obtain a solution 2D containing the acid-modified polypropylene. (Step 3D) A step of separating the solution 2D into a crude polymer composition and a filtrate to obtain the crude polymer composition.

[0114] The method for producing a crude polymer composition according to an embodiment of the present invention may be included as a step in the method for producing the polymer composition.

[0115] The method for producing a crude polymer composition according to an embodiment of the present invention can include, after step 3D, steps 4D to 5D in this order: (Step 4D) A step of purifying the filtrate to obtain a treated solvent; and (Step 5D) A step of reusing the treated solvent as part or all of the reaction solvent in step 1D.

[0116] [Production Method D: Step 1D] Step 1D in Production Method D is a step of heating and dissolving polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and derivatives thereof, to obtain a solution 1D containing the polypropylene and the acid component.

[0117] (Components in Step 1D) The components in Step 1D of Production Method D, namely, polypropylene, acid component, aromatic hydrocarbon solvent, and reaction solvent, are the same as those described in Step 1A of Production Method A.

[0118] (Heat Dissolution) The heat dissolution conditions may be the same as those described for step 1A of production method A.

[0119] [Production Method D: Step 2D] Step 2D in Production Method D is a step of adding an organic peroxide to Solution 1D to obtain Solution 2D containing acid-modified polypropylene.

[0120] The organic peroxide, which is a component in step 2D of production method D, is the same as that described in step 2A of production method A.

[0121] (Reaction Conditions) The reaction conditions after adding the organic peroxide may be the same as those described in step 2A of production method A.

[0122] [Production Method D: Step 3D] Step 3D in Production Method D is a step of separating the solution 2D into a crude polymer composition and a filtrate to obtain the crude polymer composition.

[0123] (Components in Step 3D) The filtrate, which is a component in Step 3D of Production Method D, is the same as that described in Step 3A of Production Method A.

[0124] (Method for Separating Polymer Composition from Solution 2D) The method for separating the polymer composition from solution 2D can be the same as that described for step 3A of production method A. For example, step 3D can include a step of separating solution 2D into the polymer composition and a filtrate by crystallization purification.

[0125] [Production Method D: Step 4D] Step 4D in Production Method D is a step of purifying the filtrate to obtain a treated solvent.

[0126] (Components in Step 4D) The treatment solvent, which is a component in Step 4D of Production Method D, is the same as that described for Step 4A of Production Method A. For example, the total content of at least one selected from the group consisting of acetone and its derivatives relative to the total mass of the treatment solvent is preferably 0.2 mass% or less, more preferably 0.15 mass% or less, and even more preferably 0.1 mass% or less. The lower the content, the better, and there is no particular lower limit, but it can be, for example, 0.001 mass% or more, 0.005 mass% or more, or 0.01 mass% or more.

[0127] (Method for Obtaining Treated Solvent) The treated solvent is obtained by purifying the filtrate. The treatment and purification method can be the same as that described for step 4A of production method A. For example, the purification method in step 4D preferably includes distillation purification. The distillation purification can also be the same as that described for step 4A of production method A.

[0128] [Production Method D: Step 5D] ​​Step 5D in Production Method D is a step of reusing the treatment solvent obtained in Step 4D as part or all of the reaction solvent in Step 1D.

[0129] The treatment solvent obtained in step 4D can be reused as the reaction solvent in step 1D by the same method as described for step 5A of production method A.

[0130] [Other Steps] Production method D may include any steps other than those described above, such as bubbling nitrogen through the reaction solution before adding the organic peroxide, extracting the reaction solution with water, decolorizing the reaction solution, drying the acid-modified polypropylene, and pulverizing the acid-modified polypropylene.

[0131] <Production of Polymer Composition> [Example 1] (Reaction Solvent) Isotactic propylene homopolymer, maleic anhydride, and monochlorobenzene were placed in a glass flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, and dissolved under a nitrogen atmosphere. Dicumyl peroxide, an organic peroxide, was then added and reacted to obtain a solution. Acetone was added to this solution, and the polymer precipitated by crystallization purification was filtered off to obtain a filtrate. This filtrate was purified by distillation and reused as a reaction solvent in the production of the polymer composition of Example 1 below. The reaction solvent used in Example 1 was monochlorobenzene containing 13 ppm by mass of acetone and 53 ppm by mass of mesityl oxide.

[0132] (Production of Polymer Composition) 100 parts by mass of an isotactic propylene homopolymer having an MFR of 10 g / 10 min (measured at 230°C and 21.2 N according to JIS K 7210:2014), 19 parts by mass of maleic anhydride, and 750 parts by mass of a reaction solvent were placed in a glass flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, and dissolved at 127°C under a nitrogen atmosphere. 7 parts by mass of dicumyl peroxide, an organic peroxide, was added to the mixture through the dropping funnel at the same temperature, and the mixture was allowed to react for 9 hours with continued stirring at the same temperature. After completion of the reaction, the reaction solution was cooled to near room temperature, and acetone was added to precipitate a polymer. The precipitated polymer was filtered, and the filtered polymer was repeatedly slurry-washed with acetone. The washed polymer was dried under reduced pressure to obtain the polymer composition of Example 1 as a white powder.

[0133] Example 2 A polymer composition of Example 2 was obtained as a white powder in the same manner as in Example 1, except that monochlorobenzene containing 274 ppm by mass of acetone and 42 ppm by mass of mesityl oxide was used as the reaction solvent.

[0134] Example 3 A polymer composition of Example 3 was obtained as a white powder in the same manner as in Example 1, except that monochlorobenzene containing 503 ppm by mass of acetone and 37 ppm by mass of mesityl oxide was used as the reaction solvent.

[0135] Comparative Example 1 A polymer composition of Comparative Example 1 was obtained as a white powder in the same manner as in Example 1, except that monochlorobenzene containing 688 ppm by mass of acetone and 96 ppm by mass of mesityl oxide was used as the reaction solvent.

[0136] <Quantitative Analysis of Dimethylfuran Compounds in Polymer Composition> Using a thermal extraction GC / MS (Agilent 7890 / Agilent 5977A, manufactured by Agilent Technologies) and 2,5-dimethylfuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a standard sample, quantitative analysis of the dimethylfuran compounds in the polymer composition was carried out. The sample preparation and GC / MS analysis conditions are as follows. Note that the dimethylfuran compounds include at least one or all of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, and the total content of dimethylfuran compounds in this specification means the value measured using 2,5-dimethylfuran as a standard sample.

[0137] (Sample Preparation) 10 mg of the polymer composition obtained in the Examples and Comparative Examples was weighed and inserted into a thermal desorption tube (manufactured by Gerstel). This thermal desorption tube was inserted into a thermal desorption unit TDU (manufactured by Gerstel) at 40°C, and then the inside of the tube was purged with helium. The temperature was raised to 180°C at a rate of 12°C / sec, and thermal extraction was performed for 10 minutes. During this thermal extraction, a GC injection port CIS4 (manufactured by Gerstel) filled with quartz wool was cooled to -150°C to collect volatile components generated from the sample. The components collected by cooling at the GC injection port were vaporized by rapidly heating the collection section to 300°C, and introduced into a GC column, followed by measurement with GC / MS (Agilent 7890 / Agilent 5977A).

[0138] (GC / MS measurement conditions) Column: DB-5MSUI 30 m x 250 μm x 0.25 μm Column flow rate: 1.0 m / min Carrier gas: He Oven temperature: held at 40°C for 5 minutes, then heated to 300°C at a rate of 10°C / min. Further held at 300°C for 20 minutes. Injection mode: Solvent Split ratio: 1:50 Measurement mode: EI Scan

[0139] <YI Measurement of Sheet-Shaped Polymer Composition> (Sample Preparation) Sheets (200 x 200 x 2 mm thick) of the polymer compositions obtained in the Examples and Comparative Examples were prepared using a press molding machine (Shinto F-type hydraulic press NF-37H, manufactured by Shinto Metal Industries Co., Ltd.). The pressing conditions were as follows: Heating temperature: 160°C Preheating time: 5 minutes, no pressure Pressurization conditions: 8 MPa, 2 minutes Cooling conditions: 10 MPa, 2 minutes

[0140] (Measurement of YI) The YI of the obtained sheet was measured using a color difference meter ZE6000 manufactured by Nippon Denshoku Industries Co., Ltd.

[0141] <Measurement Results> Table 1 shows the total content of dimethylfuran compounds in the polymer compositions obtained in each of the Examples and Comparative Examples, and the YI of the sheet-shaped polymer compositions.

[0142]

[0143] As shown in Table 1, the polymer compositions of Examples 1 to 3, in which the total content of dimethylfuran compounds was less than 15 ppm by mass, exhibited a lower YI than that of Comparative Example 1.

[0144] Although various embodiments have been described above, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any manner as long as they do not deviate from the spirit of the invention.

[0145] This application is based on a Japanese patent application (Patent Application No. 2024-001830) filed on January 10, 2024, the contents of which are incorporated herein by reference.

[0146] The polymer composition according to the embodiment of the present invention causes little change in the hue of a molded product, and in particular has a small yellowness index (YI) value, and therefore can be suitably used for, for example, food packaging materials such as food packaging films and trays; medical product packaging materials such as infusion bags, nutrient food / liquid food bags, and ostomy bags; medical device parts for joining injection molded parts such as drip tubes and syringes to metal needles; medical products such as fluid transport devices such as bottles and tubes for use in medical care, and pharmaceutical containers such as pharmaceutical tubes and pharmaceutical bottles; automotive parts such as fuel tanks and fuel tubes, and automotive coolant tubes, particularly coolant tubes for electric vehicles; and battery parts such as exterior films and tab lead films for secondary batteries in the fields of electronics, automobiles, and robotics.

Claims

1. A polymer composition containing acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, wherein the total content of the dimethylfuran compound with respect to the total mass of the polymer composition is less than 15 ppm by mass.

2. The polymer composition according to claim 1, wherein the total content of the dimethylfuran compound with respect to the total mass of the polymer composition is 0.5 ppm by mass or more.

3. The polymer composition according to claim 1, wherein the total content of the dimethylfuran compound with respect to the total mass of the polymer composition is 1 ppm by mass or more.

4. The polymer composition according to claim 1, wherein the total content of the dimethylfuran compound with respect to the total mass of the polymer composition is 12 ppm by mass or less.

5. The polymer composition according to claim 1, which conforms to JIS K 7210:2014 and has a melt flow rate measured under the conditions of 180 °C and a load of 21.2 N of 150 to 2000 g / 10 min.

6. The polymer composition according to claim 1, wherein the grafting rate of the acid-modified polypropylene is 1.0 to 20% by mass.

7. A food packaging material containing the polymer composition according to any one of claims 1 to 6.

8. A medical product containing the polymer composition according to any one of claims 1 to 6.

9. An automotive part containing the polymer composition according to any one of claims 1 to 6.

10. A battery part containing the polymer composition according to any one of claims 1 to 6.

11. Use of the polymer composition according to any one of claims 1 to 6 for a food packaging material.

12. Use of the polymer composition according to any one of claims 1 to 6 for a medical product.

13. Use of the polymer composition according to any one of claims 1 to 6 for an automotive part.

14. Use of the polymer composition according to any one of claims 1 to 6 for a battery part.

15. A method for producing the polymer composition according to any one of claims 1 to 6, the production method including the following steps 1A to 5A in this order. (Step 1A) In a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives, polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and their derivatives are heated and dissolved to obtain a solution 1A containing the polypropylene and the acid component. (Step 2A) An organic peroxide is added to the solution 1A to obtain a solution 2A containing acid-modified polypropylene. (Step 3A) The solution 2A is separated into a polymer composition and a filtrate to obtain the polymer composition. (Step 4A) The filtrate is purified to obtain a treated solvent. (Step 5A) The treated solvent is reused as part or all of the reaction solvent in Step 1A.

16. The production method according to claim 15, wherein Step 3A includes a step of separating the solution 2A into the polymer composition and the filtrate by crystallization purification.

17. The production method according to claim 15, wherein the purification treatment in Step 4A includes distillation purification.

18. The production method according to claim 15, wherein the total content of at least one selected from the group consisting of acetone and its derivatives with respect to the total mass of the treated solvent is 0.2% by mass or less.

19. A method for producing the polymer composition according to any one of claims 1 to 6, the production method including the following steps 1B to 4B in this order. (Step 1B) In a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives, polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and their derivatives are heated and dissolved to obtain a solution 1B containing the polypropylene and the acid component. (Step 2B) An organic peroxide is added to the solution 1B to obtain a solution 2B containing acid-modified polypropylene. (Step 3B) The solution 2B is separated into a polymer composition and a filtrate by crystallization purification to obtain the polymer composition. (Step 4B) The filtrate is subjected to distillation purification.

20. A method for producing a solution of a crude polymer composition containing acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, the production method including the following steps 1C to 2C in this order. (Step 1C) In a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives, polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and their derivatives are heated and dissolved to obtain a solution 1C containing the polypropylene and the acid component. (Step 2C) An organic peroxide is added to the solution 1C to obtain a solution 2C of a crude polymer composition containing acid-modified polypropylene.

21. A method for producing a crude polymer composition containing acid-modified polypropylene and at least one dimethylfuran compound selected from the group consisting of 2,5-dimethylfuran, 2,4-dimethylfuran, and 3,4-dimethylfuran, the production method including the following steps 1D to 3D in this order. (Step 1D) In a reaction solvent containing an aromatic hydrocarbon solvent and at least one selected from the group consisting of acetone and its derivatives, polypropylene and at least one acid component selected from the group consisting of unsaturated carboxylic acids and their derivatives are heated and dissolved to obtain a solution 1D containing the polypropylene and the acid component. (Step 2D) An organic peroxide is added to the solution 1D to obtain a solution 2D containing acid-modified polypropylene. (Step 3D) The solution 2D is separated into a crude polymer composition and a filtrate to obtain the crude polymer composition.

22. The production method according to claim 21, including the following steps 4D to 5D in this order after step 3D. (Step 4D) A step of purifying the filtrate to obtain a treated solvent. (Step 5D) A step of recycling the treated solvent as part or all of the reaction solvent in step 1D.

23. The production method according to claim 21, wherein step 3D includes a step of separating the solution 2D into the crude polymer composition and the filtrate by crystallization purification.

24. The production method according to claim 22, wherein the purification treatment in step 4D includes distillation purification.

25. The production method according to claim 22, wherein the total content of at least one selected from the group consisting of acetone and its derivatives is 0.2% by mass or less based on the total mass of the treatment solvent.

26. The production method according to claim 21, wherein the total content of the dimethylfuran compound is less than 15 ppm by mass based on the total mass of the crude polymer composition.

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